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Sample records for nonpolar gentamicin resistance

  1. The Rapid Emergence of High Level Gentamicin Resistance in Enterococci

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    Kevin R Forward

    1990-01-01

    Full Text Available The proportion of enterococci isolated from blood and urine cultures that were highly resistant to gentamicin and streptomycin were determined. No blood or urine isolates highly resistant to gentamicin were seen in 1983, whereas by 1986–87 25% of blood and 17% of urine isolates were highly resistant. The rapid emergence of gentamicin resistance has serious implications for patients with life threatening enterococcal disease.

  2. Gentamicin resistance among Escherichia coli strains isolated in neonatal sepsis.

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    Hasvold, J; Bradford, L; Nelson, C; Harrison, C; Attar, M; Stillwell, T

    2013-01-01

    Neonatal sepsis is a significant cause of morbidity and mortality among term and preterm infants. Ampicillin and gentamicin are standard empiric therapy for early onset sepsis. Four cases of neonatal sepsis secondary to Escherichia coli (E. coli) found to be gentamicin resistant occurred within a five week period in one neonatal intensive care unit (NICU). To determine whether these cases could be tied to a single vector of transmission, and to more broadly evaluate the incidence of gentamicin resistant strains of E. coli in the neonatal population at our institution compared to other centers, we reviewed the charts of the four neonates (Infants A through D) and their mothers. The E. coli isolates were sent for Pulse Field Gel Electrophoresis (PFGE) to evaluate for genetic similarity between strains. We also reviewed all positive E. coli cultures from one NICU over a two year period. Infants A and B had genetically indistinguishable strains which matched that of urine and placental cultures of Infant B's mother. Infant C had a genetically distinct organism. Infant D, the identical twin of Infant C, did not have typing performed. Review of all cultures positive for E. coli at our institution showed a 12.9 percent incidence of gentamicin-resistance. A review of other studies showed that rates of resistance vary considerably by institution. We conclude that gentamicin-resistant E. coli is a relatively uncommon cause of neonatal sepsis, but should remain a consideration in patients who deteriorate despite initiation of empiric antibiotics.

  3. Correlation between apramycin and gentamicin use in pigs and an increasing reservoir of gentamicin-resistant Escherichia coli

    DEFF Research Database (Denmark)

    Jensen, Vibeke Frøkjær; Jakobsen, Lotte; Emborg, Hanne-Dorthe;

    2006-01-01

    and gentamicin resistance in Escherichia coli strains from pork, healthy pigs and diagnostic submissions from pigs and to investigate potential relationships to the use of apramycin and gentamicin at farm and national levels. Methods: Data on Danish E. coli isolates from healthy pigs (indicator bacteria......-2004). The genetic background for gentamicin resistance was investigated by PCR. Relationships between antimicrobial usage and resistance were analysed by chi(2) test and logistic regression. Results: At the farm level, the occurrence of apramycin/gentamicin cross-resistance was correlated to the use of apramycin (P...... resistance in clinical E. coli 0149 isolates was significantly correlated with the amounts and duration of apramycin use. The aac(3)-IV gene was detected in all tested cross-resistant isolates. Conclusions: Apramycin consumption...

  4. Community Acquisition of Gentamicin-Sensitive Methicillin-Resistant Staphylococcus aureus in Southeast Queensland, Australia

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    Nimmo, Graeme R.; Schooneveldt, Jacqueline; O'Kane, Gabrielle; McCall, Brad; Vickery, Alison

    2000-01-01

    Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) susceptible to gentamicin has been reported in a number of countries in the 1990s. To study the acquisition of gentamicin-sensitive MRSA (GS-MRSA) in southeast Queensland and the relatedness of GS-MRSA to other strains of MRSA, 35 cases of infection due to GS-MRSA from October 1997 through September 1998 were examined retrospectively to determine the mode of acquisition and risk factors for MRSA acquisition. Thirty-one isol...

  5. Chromosomally and Extrachromosomally Mediated High-Level Gentamicin Resistance in Streptococcus agalactiae.

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    Sendi, Parham; Furitsch, Martina; Mauerer, Stefanie; Florindo, Carlos; Kahl, Barbara C; Shabayek, Sarah; Berner, Reinhard; Spellerberg, Barbara

    2016-01-04

    Streptococcus agalactiae (group B Streptococcus [GBS]) is a leading cause of sepsis in neonates. The rate of invasive GBS disease in nonpregnant adults also continues to climb. Aminoglycosides alone have little or no effect on GBS, but synergistic killing with penicillin has been shown in vitro. High-level gentamicin resistance (HLGR) in GBS isolates, however, leads to the loss of a synergistic effect. We therefore performed a multicenter study to determine the frequency of HLGR GBS isolates and to elucidate the molecular mechanisms leading to gentamicin resistance. From eight centers in four countries, 1,128 invasive and colonizing GBS isolates were pooled and investigated for the presence of HLGR. We identified two strains that displayed HLGR (BSU1203 and BSU452), both of which carried the aacA-aphD gene, typically conferring HLGR. However, only one strain (BSU1203) also carried the previously described chromosomal gentamicin resistance transposon designated Tn3706. For the other strain (BSU452), plasmid purification and subsequent DNA sequencing resulted in the detection of plasmid pIP501 carrying a remnant of a Tn3 family transposon. Its ability to confer HLGR was proven by transfer into an Enterococcus faecalis isolate. Conversely, loss of HLGR was documented after curing both GBS BSU452 and the transformed E. faecalis strain from the plasmid. This is the first report showing plasmid-mediated HLGR in GBS. Thus, in our clinical GBS isolates, HLGR is mediated both chromosomally and extrachromosomally.

  6. Subcutaneous gentamicin injection around the cuff in treatment of resistant exit site infection in peritoneal dialysis patients: a pilot study.

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    Dizdar, Oguzhan Sıtkı; Ozer, Ozerhan; Erdem, Selahattin; Gunal, Ali Ihsan

    2017-01-01

    One of the most common complications of the peritoneal dialysis (PD) is the infection of the exit site of the peritoneal catheter. The aim of the present study was to evaluate the efficacy of the subcutaneous gentamicin injection around the cuff as a part of routine treatment of the resistant exit site infection (ESI). If the exit site remains infected after a 2-week systemic antibiotics treatment, it is defined as resistant ESI. In these cases, systemic antibiotics were discontinued and a subcutaneous 40-mg gentamicin injection was administered around the external cuff of the PD catheter every 3 days. A total of three or four injections were given to each patient. A subcutaneous gentamicin injection was administered around the cuff in thirteen patients for the treatment of resistant ESI over a 2-year period. The median follow-up time in cured patients was 12 months. Eleven of the thirteen patients had been apparently cured of their resistant ESI, with no recurrence. None of the patients had a gentamicin-resistant species. Subcutaneous gentamicin-related adverse effect was not observed in any patient. Subcutaneous gentamicin injection around the cuff is a well-tolerated and effective strategy for treating resistant ESI. To gain widespread approval of this therapy and reach a consensus about ESI management, additional studies are needed.

  7. Novel pathways for ameliorating the fitness cost of gentamicin resistant small colony variants

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Paulander, Wilhelm Erik Axel; Leng, Bingfeng

    2016-01-01

    mutations in the menaquinone and hemin biosynthesis pathways, which caused a significant reduction in exponential growth rates relative to wild type (WT; 0.59-0.72) and reduced membrane potentials. Fifty independent lineages of the low-fitness, resistant mutants were serially passaged for up to 500......Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby...... in the absence of gentamicin, 12 out of 15 lineages derived from SCVs with point mutations acquired intra-codonic suppressor mutations restoring membrane potential, growth rate, gentamicin susceptibility and colony size to WT levels. For the SCVs carrying deletions, all lineages enhanced fitness independent...

  8. In vitro antibacterial activity of seven Indian spices against high level gentamicin resistant strains of enterococci

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    Bipin, Chapagain; Chitra, Pai (Bhat); Minakshi, Bhattacharjee

    2015-01-01

    Introduction The aim of the study was to explore the in vitro antibacterial activity of seven ethanolic extracts of spices against high level gentamicin resistant (HLGR) enterococci isolated from human clinical samples. Material and methods Two hundred and fifteen enterococcal strains were isolated from clinical samples. High level gentamicin resistance in ethanolic extracts of cumin (Cuminum cyminum), cinnamon (Cinnamomum zeylanicum), ginger (Zingiber officinale), fenugreek (Trigonella foenum-graecum), cloves (Syzygium aromaticum), cardamom (Elettaria cardamomum Maton) and black pepper (Piper nigrum) were prepared using Soxhlet apparatus. The antibacterial effect of the extracts was studied using the well diffusion method. Statistical analysis was carried out by χ2 test using SPSS 17 software. Results Only cinnamon and ginger were found to have activity against all the isolates, whereas cumin and cloves had a variable effect on the strains. Fenugreek, black pepper and cardamom did not show any effect on the isolates. The zone diameter of inhibition obtained for cinnamon, ginger, cloves and cumin was in the range 31–34 mm, 27–30 mm, 25–26 mm and 19–20 mm respectively. Conclusions Cinnamomum zeylanicum and Z. officinale showed the maximum antibacterial activity against the enterococcal isolates followed by S. aromaticum and C. cyminum. The findings of the study show that spices used in the study can contribute to the development of potential antimicrobial agents for inclusion in the anti-enterococcal treatment regimen. PMID:26322099

  9. Novel Glycoconjugate of 8-Fluoro Norfloxacin Derivatives as Gentamicin-resistant Staphylococcus aureus Inhibitors: Synthesis and Molecular Modelling Studies.

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    Azad, Chandra S; Bhunia, Shome S; Krishna, Atul; Shukla, Praveen K; Saxena, Anil K

    2015-10-01

    Antibiotic resistance has been the subject of interest in clinical practice due to high prevalence of antibiotic-resistant pathogenic organisms. In view of the prevalence of lesser resistance in antibiotics belonging to aminoglycoside class of compounds viz. Food and Drug Administration-approved gentamicin for the treatment of Staphylococcus infections, which also has instances of resistance in the clinical isolates of Staphylococcus aureus, a series of novel glycoconjugates of 8-fluoro norfloxacin analogues with high regio-selectivity by employing copper (I)-catalyzed 1, 3-dipolar cycloaddition of 1-O-propargyl monosaccharides has been synthesized and evaluated for the antibacterial activity against gentamicin resistance Staphylococcus aureus. Among these compounds, the compound 10g showed better antibacterial activity (MIC = 3.12 μg/ml) than gentamicin (Escherichia coli (12.5 μg/ml), Staphylococcus aureus (6.25 μg/ml) and Klebsiella pneumonia (6.25 μg/ml), including gentamicin resistant (>50 μg/ml) strain in vitro). The docking studies suggest DNA gyrase of Staphylococcus aureus as a probable target for the antibacterial action of compound 10g. © 2014 John Wiley & Sons A/S.

  10. Detection of the esp gene in high-level gentamicin resistant Enterococcus faecalis strains from pet animals in Japan.

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    Harada, Tetsuya; Tsuji, Noboru; Otsuki, Koichi; Murase, Toshiyuki

    2005-03-20

    We investigated the prevalence of the esp gene and the susceptibility to gentamicin in Enterococcus faecalis and E. faecium strains obtained from pet animals. Nine of 30 E. faecalis and 2 of 38 E. faecium strains from the pet animals had the esp gene. Three esp-positive E. faecalis strains, which were isolated from two dogs and a cat, showed gentamicin MICs of > or =256 microg/ml and harbored the high-level gentamicin resistance (HLGR) gene, aac(6')-Ie-aph(2'')-Ia. Of the nine esp-positive E. faecalis strains, five, including the three strains with the HLGR gene, were closely related by numerical analysis of PFGE patterns. Longitudinal investigation needs to elucidate whether the HLGR gene was incorporated into a subpopulation of the esp-positive E. faecalis.

  11. Temperature-dependent gentamicin resistance of Francisella tularensis is mediated by uptake modulation

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    Kathleen eLoughman

    2016-01-01

    Full Text Available Gentamicin (Gm is an aminoglycoside commonly used to treat bacterial infections such as tularemia – the disease caused by Francisella tularensis. In addition to being pathogenic, F. tularensis is found in environmental niches such as soil where this bacterium likely encounters Gm producers (Micromonospora sp.. Here we show that F. tularensis exhibits increased resistance to Gm at ambient temperature (26°C compared to mammalian body temperature (37°C. To evaluate whether F. tularensis was less permeable to Gm at 26°C, a fluorescent marker [Texas Red (Tr] was conjugated with Gm, yielding Tr-Gm. Bacteria incubated at 26°C showed reduced fluorescence compared to those at 37°C when exposed to Tr-Gm suggesting that uptake of Gm was reduced at 26°C. Unconjugated Gm competitively inhibited uptake of Tr-Gm, demonstrating that this fluorescent compound was taken up similarly to unconjugated Gm. Lysates of F. tularensis bacteria incubated with Gm at 37°C inhibited the growth of Escherichia coli significantly more than lysates from bacteria incubated at 26°C, further indicating reduced uptake at this lower temperature. Other facultative pathogens (Listeria monocytogenes and Klebsiella pneumoniae exhibited increased resistance to Gm at 26°C suggesting that the results generated using F. tularensis may be generalizable to diverse bacteria. Regulation of the uptake of antibiotics provides a mechanism by which facultative pathogens survive alongside antibiotic-producing microbes in nature.

  12. Effect of Catechins, Green tea Extract and Methylxanthines in Combination with Gentamicin Against Staphylococcus aureus and Pseudomonas aeruginosa - Combination therapy against resistant bacteria -

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    Bibi Sedigheh Fazly Bazzaz

    2016-12-01

    Full Text Available Objectives: Bacterial resistant infections have become a global health challenge and threaten the society’s health. Thus, an urgent need exists to find ways to combat resistant pathogens. One promising approach to overcoming bacterial resistance is the use of herbal products. Green tea catechins, the major green tea polyphenols, show antimicrobial activity against resistant pathogens. The present study aimed to investigate the effect of catechins, green tea extract, and methylxanthines in combination with gentamicin against standard and clinical isolates of Staphylococcus aureus (S. aureus and the standard strain of Pseudomonas aeruginosa (P. aeruginosa. Methods: The minimum inhibitory concentration (MIC and the minimum bactericidal concentration (MBC values of different agents against bacterial strains were determined. The interactions of green tea extract, epigallate catechin, epigallocatechin gallate, two types of methylxanthine, caffeine, and theophylline with gentamicin were studied in vitro by using a checkerboard method and calculating the fraction inhibitory concentration index (FICI. Results: The MICs of gentamicin against bacterial strains were in the range of 0.312 - 320 μg/mL. The MIC values of both types of catechins were 62.5 - 250 μg/ mL. Green tea extract showed insufficient antibacterial activity when used alone. Methylxanthines had no intrinsic inhibitory activity against any of the bacterial strains tested. When green tea extract and catechins were combined with gentamicin, the MIC values of gentamicin against the standard strains and a clinical isolate were reduced, and synergistic activities were observed (FICI < 1. A combination of caffeine with gentamicin did not alter the MIC values of gentamicin. Conclusion: The results of the present study revealed that green tea extract and catechins potentiated the antimicrobial action of gentamicin against some clinical isolates of S. aureus and standard P. aeruginosa strains

  13. In vitro activity of RPR 106972 alone and in combination with vancomycin, ampicillin, and gentamicin against multidrug-resistant enterococci.

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    Messick, C R; Woodward, J; Pendland, S L

    1998-10-01

    This investigation used checkerboard and time-kill assays to evaluate the in vitro activity of RPR 106972 (45% pristinamycin IB and 55% pristinamycin IIB) alone and in combination with vancomycin or ampicillin +/- gentamicin against multidrug-resistant enterococci. The checkerboard procedure resulted in synergistic or additive effects in 91% of the isolates with the combination of RPR 106972 plus vancomycin versus 68% with RPR 106972 plus ampicillin. The addition of gentamicin to either combination resulted in synergistic or additive results in 100% of the isolates. Inhibitory activity was observed with the time-kill assay with mean change in log10 CFU/mL at 24 h of -0.31 for RPR 106972, 3.3 for vancomycin, -0.46 for RPR 106972 plus vancomycin, and -0.35 for RPR 106972 plus vancomycin and gentamicin. No antagonism was noted with any of the combinations. RPR 106972 demonstrates good inhibitory activity against Enterococcus faecium and may prove useful in the treatment of enterococcal infections.

  14. Molecular screening of virulence genes in high-level gentamicin-resistant Enterococcus faecalis and Enterococcus faecium isolated from clinical specimens in Northwest Iran

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    A Hasani

    2012-01-01

    Full Text Available Purpose: The present study screened clinical isolates of Enterococcus faecalis and Enterococcus faecium to determine the prevalence of high-level gentamicin-resistant enterococci and the potential virulence genes among them. Materials and Methods: Clinical enterococcal isolates were obtained from three university teaching hospitals in Northwest Iran. Isolated enterococci were identified phenotypically followed by antibiotic susceptibility testing. Multiplex PCR was performed for the detection of genus, species-specific targets, gentamicin resistance, and potential virulence genes. Results: Of 220 enterococcal isolates, 133 (60.45% isolates were identified as high-level gentamicin-resistant. Of these isolates, 79 (59.4% and 54 (40.6% were E. faecalis and E. faecium, respectively. All high-level gentamicin-resistant strains carried aac(6′Ie-aph(2″Ia. Of 220 isolates, 65.9% were positive for gelE, and 55%, 53.6%, 51.8%, and 49.5% of isolates were positive for cpd, asa1, ace, and esp, respectively. Phenotypically detected β-haemolytic strains (19.54% were found to possess cylL ls MAB. Conclusion: The study revealed that high-level gentamicin-resistance was related to the presence of aac(6′Ie-aph(2″Ia. Isolated enterococci harboured potential virulence determinants, which were more common among E. faecalis than among E. faecium strains.

  15. Characterisation, dissemination and persistence of gentamicin resistant Escherichia coli from a Danish university hospital to the waste water environment

    DEFF Research Database (Denmark)

    Jakobsen, Lotte; Sandvang, Dorthe; Hansen, Lars H

    2008-01-01

    in waste water from the residential area. PFGE profiling revealed no spread of specific patient isolates to the waste water. The aac(3)-II gene was detected both in patient and waste water isolates. Furthermore horizontal transfer of the aac(3)-II gene of patient origin to a recipient was shown in vitro......, indicating a potential spread of the gene from patient isolates to waste water isolates. Regardless of origin, most isolates exhibited multi-resistance and contained several virulence genes. In conclusion, our study showed a possible spread of aac(3)-II from the hospital to the waste water. Most of the GEN......The aim of the study was to investigate the potential spread of gentamicin resistant (GEN(R)) Escherichia coli isolates or GEN(R) determinants from a Danish university hospital to the waste water environment. Waste water samples were collected monthly from the outlets of the hospital bed wards...

  16. Nucleotide sequence of the aacC2 gene, a gentamicin resistance determinant involved in a hospital epidemic of multiply resistant members of the family Enterobacteriaceae.

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    Vliegenthart, J S; Ketelaar-van Gaalen, P A; Van de Klundert, J A

    1989-01-01

    A gentamicin resistance determinant of a conjugative plasmid from Enterobacter cloacae was cloned on a 3.2-kilobase fragment in the PstI site of pBR322. Substrate profiles for eight aminoglycosides at three concentrations showed that the resistance was due to aminoglycoside-(3)-N-acetyltransferase isoenzyme II. Insertion mapping by the gamma-delta transposon revealed that the size of the gene was approximately 1 kilobase. Nucleotide sequencing of the aacC2 gene identified an open reading fram...

  17. The prevalence and clonal expansion of high-level gentamicin-resistant enterococci isolated from blood cultures in a Dutch university hospital

    NARCIS (Netherlands)

    N.P.W.C.J. van den Braak (Nicole); A.F. van Belkum (Alex); D. Kreft; R. te Witt (René); H.A. Verbrugh (Henri); H.P. Endtz (Hubert)

    1999-01-01

    textabstractWe studied the prevalence and clonality of high-level gentamicin-resistant enterococci (HLGRE) in a Dutch university hospital. Of 238 enterococcal strains isolated from blood cultures between 1991 and 1997, 57 were HLGRE. Genomic analysis of these strains re

  18. Nonpolar resistive memory switching with all four possible resistive switching modes in amorphous LaHoO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Yogesh; Pavunny, Shojan P.; Katiyar, Ram S., E-mail: rkatiyar@hpcf.upr.edu [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00936-8377 (United States); Fachini, Esteban [General Studies College, University of Puerto Rico, San Juan, Puerto Rico 00931 (United States); Scott, James F. [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB0 3HE (United Kingdom)

    2015-09-07

    We studied the resistive memory switching in pulsed laser deposited amorphous LaHoO{sub 3} (a-LHO) thin films for non-volatile resistive random access memory applications. Nonpolar resistive switching (RS) was achieved in Pt/a-LHO/Pt memory cells with all four possible RS modes (i.e., positive unipolar, positive bipolar, negative unipolar, and negative bipolar) having high R{sub ON}/R{sub OFF} ratios (in the range of ∼10{sup 4}–10{sup 5}) and non-overlapping switching voltages (set voltage, V{sub ON} ∼ ±3.6–4.2 V and reset voltage, V{sub OFF} ∼ ±1.3–1.6 V) with a small variation of about ±5–8%. Temperature dependent current-voltage (I–V) characteristics indicated the metallic conduction in low resistance states (LRS). We believe that the formation (set) and rupture (reset) of mixed conducting filaments formed out of oxygen vacancies and metallic Ho atoms could be responsible for the change in the resistance states of the memory cell. Detailed analysis of I–V characteristics further corroborated the formation of conductive nanofilaments based on metal-like (Ohmic) conduction in LRS. Simmons-Schottky emission was found to be the dominant charge transport mechanism in the high resistance state.

  19. Comparative Study of Bacteremias Caused by Enterococcus spp. with and without High-Level Resistance to Gentamicin

    Science.gov (United States)

    Caballero-Granado, Francisco Javier; Cisneros, J. M.; Luque, R.; Torres-Tortosa, M.; Gamboa, F.; Díez, F.; Villanueva, J. L.; Pérez-Cano, R.; Pasquau, J.; Merino, D.; Menchero, A.; Mora, D.; López-Ruz, M. A.; Vergara, A.; Infecciosas, for the Grupo Andaluz Para El Estudio De Las Enfermedades

    1998-01-01

    A prospective, multicenter study was carried out over a period of 10 months. All patients with clinically significant bacteremia caused by Enterococcus spp. were included. The epidemiological, microbiological, clinical, and prognostic features and the relationship of these features to the presence of high-level resistance to gentamicin (HLRG) were studied. Ninety-three patients with enterococcal bacteremia were included, and 31 of these cases were caused by HLRG (33%). The multivariate analysis selected chronic renal failure, intensive care unit stay, previous use of antimicrobial agents, and Enterococcus faecalis species as the independent risk factors that influenced the development of HLRG. The strains with HLRG showed lower levels of susceptibility to penicillin and ciprofloxacin. Clinical features (except for chronic renal failure) were similar in both groups of patients. HLRG did not influence the prognosis for patients with enterococcal bacteremia in terms of either the crude mortality rate (29% for patients with bacteremia caused by enterococci with HLRG and 28% for patients not infected with strains with HLRG) or the hospital stay after the acquisition of enterococcal bacteremia. Hemodynamic compromise, inappropriate antimicrobial therapy, and mechanical ventilation were revealed in the multivariate analysis to be the independent risk factors for mortality. Prolonged hospitalization was associated with the nosocomial acquisition of bacteremia and polymicrobial infections. PMID:9466769

  20. Rapid emergence of secondary resistance to gentamicin and colistin following selective digestive decontamination in patients with KPC-2-producing Klebsiella pneumoniae: a single-centre experience.

    Science.gov (United States)

    Lübbert, Christoph; Faucheux, Sarah; Becker-Rux, Diana; Laudi, Sven; Dürrbeck, Axel; Busch, Thilo; Gastmeier, Petra; Eckmanns, Tim; Rodloff, Arne C; Kaisers, Udo X

    2013-12-01

    After a single patient was transferred to Leipzig University Hospital from a hospital in Rhodes, Greece, the hospital experienced the largest outbreak due to a KPC-2-producing Klebsiella pneumoniae (KPC-2-KP) strain thus far observed in Germany. Ninety patients hospitalised between July 2010 and October 2012 were affected. In an attempt to eliminate KPC-2-KP from their digestive tracts, 14 consecutive patients (16%) were treated with a short course (7 days) of selective digestive decontamination (SDD), employing colistin (1 million units q.i.d.) and gentamicin (80 mg q.i.d.) as oral solutions, and applying colistin/gentamicin gel (0.5 g) to the oral cavity. In a retrospective analysis, these 14 SDD patients were compared with the remaining 76 patients harbouring KPC-2-KP. KPC-2-KP carrier status was followed in all 14 SDD patients by submitting stool samples to KPC-specific PCR. The mean follow-up period was 48 days (range 12-103 days). Successful elimination of KPC-2-KP was defined as a minimum of three consecutive negative PCR test results separated by ≥48 h each. Decolonisation of KPC-2-KP was achieved in 6/14 patients (43%) after a mean of 21 days (range 12-40 days), but was also observed in 23/76 (30%) of the non-SDD controls (P = 0.102). SDD treatment resulted in the development of secondary resistance to colistin (19% increase in resistance rate) and gentamicin (45% increase) in post-treatment isolates. In the control group, no secondary resistance occurred. We conclude that the SDD protocol applied in this study was not sufficiently effective for decolonisation and was associated with resistance development.

  1. Comparative study of bacteremias caused by Enterococcus spp. with and without high-level resistance to gentamicin. The Grupo Andaluz para el estudio de las Enfermedades Infecciosas.

    Science.gov (United States)

    Caballero-Granado, F J; Cisneros, J M; Luque, R; Torres-Tortosa, M; Gamboa, F; Díez, F; Villanueva, J L; Pérez-Cano, R; Pasquau, J; Merino, D; Menchero, A; Mora, D; López-Ruz, M A; Vergara, A

    1998-02-01

    A prospective, multicenter study was carried out over a period of 10 months. All patients with clinically significant bacteremia caused by Enterococcus spp. were included. The epidemiological, microbiological, clinical, and prognostic features and the relationship of these features to the presence of high-level resistance to gentamicin (HLRG) were studied. Ninety-three patients with enterococcal bacteremia were included, and 31 of these cases were caused by HLRG (33%). The multivariate analysis selected chronic renal failure, intensive care unit stay, previous use of antimicrobial agents, and Enterococcus faecalis species as the independent risk factors that influenced the development of HLRG. The strains with HLRG showed lower levels of susceptibility to penicillin and ciprofloxacin. Clinical features (except for chronic renal failure) were similar in both groups of patients. HLRG did not influence the prognosis for patients with enterococcal bacteremia in terms of either the crude mortality rate (29% for patients with bacteremia caused by enterococci with HLRG and 28% for patients not infected with strains with HLRG) or the hospital stay after the acquisition of enterococcal bacteremia. Hemodynamic compromise, inappropriate antimicrobial therapy, and mechanical ventilation were revealed in the multivariate analysis to be the independent risk factors for mortality. Prolonged hospitalization was associated with the nosocomial acquisition of bacteremia and polymicrobial infections.

  2. Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci

    NARCIS (Netherlands)

    Subbiandoss, Guruprakash; Sharifi, Shahriar; Grijpma, Dirk W.; Laurent, Sophie; van der Mei, Henny C.; Mahmoudi, Morteza; Busscher, Henk J.

    2012-01-01

    Biofilms on biomaterial implants are hard to eradicate with antibiotics due to the protection offered by the biofilm mode of growth, especially when caused by antibiotic-resistant strains. Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as

  3. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles

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    Chang, Hung-Yu; Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tu, Sheng-Hung [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Tsao, Heng-Kwong, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering and Department of Physics, National Central University, Jhongli 320, Taiwan (China)

    2014-08-07

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n{sup ′}) motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n{sup ′}-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  4. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles.

    Science.gov (United States)

    Chang, Hung-Yu; Tu, Sheng-Hung; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-08-01

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n') motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n'-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  5. Gentamicin nephrotoxicity: Animal experimental correlate with human pharmacovigilance outcome

    Directory of Open Access Journals (Sweden)

    Olufunsho Awodele

    2015-04-01

    Full Text Available Background: National Agency for Food and Drugs Administration and Control (NAFDAC, which is responsible for pharmacovigilance activity in Nigeria, recently withdrew injection gentamicin 280 mg, used in the management of life-threatening and multidrug-resistant infections from circulation, due to reported toxicity. Thus, this study aimed to investigate the toxicity profile of the commonly used strengths (80 mg and 280 mg of gentamicin on kidney using animal models. Methods: Animals were divided into five groups of 16 rats each. For rats of groups 1 and 2, gentamicin (1.14 mg/kg each group was administered intramuscularly twice daily for 7 and 14 days, respectively, after which eight of them were sacrificed by cervical dislocation. Blood was collected via cardiac puncture and the kidneys were carefully removed and weighed immediately. The remaining eight animals were kept for reversibility study for another 7 and 14 days, respectively. For groups 3 and 4, gentamicin (4 mg/kg each group was administered as a single daily dose for 7 and 14 days, respectively, and eight animals from the groups were subjected to reversibility study for 7 and 14 days, respectively. Group 5, the control group animals, were given 10 ml/kg distilled water for 14 days. Histopathology of the kidneys, serum creatinine levels, and antioxidant enzyme activities were investigated. Results: Significant increase (p ≤ 0.001 in the level of creatinine of rats administered 4.0 mg/kg for 14 days was observed compared with all other groups. Significant (p ≤ 0.001 elevations in the lipid peroxidation in all gentamicin-administered animals and acute tubular necrosis in most of the gentamicin-administered animals were observed. Conclusion: Toxicity profile of gentamicin on the kidneys is dependent on both dose and duration of administration. The findings justify the decision made by NAFDAC to ban the use of high-dose inj. gentamicin 280 mg in Nigeria.

  6. A biodegradable gentamicin-hydroxyapatite-coating for infection prophylaxis in cementless hip prostheses

    Directory of Open Access Journals (Sweden)

    D Neut

    2015-01-01

    Full Text Available A degradable, poly (lactic-co-glycolic acid (PLGA, gentamicin-loaded prophylactic coating for hydroxyapatite (HA-coated cementless hip prostheses is developed with similar antibacterial efficacy as offered by gentamicin-loaded cements for fixing traditional, cemented prostheses in bone. We describe the development pathway, from in vitro investigation of antibiotic release and antibacterial properties of this PLGA-gentamicin-HA-coating in different in vitro models to an evaluation of its efficacy in preventing implant-related infection in rabbits. Bone in-growth in the absence and presence of the coating was investigated in a canine model. The PLGA-gentamicin-HA-coating showed high-burst release, with antibacterial efficacy in agar-assays completely disappearing after 4 days, minimising risk of inducing antibiotic resistance. Gentamicin-sensitive and gentamicin-resistant staphylococci were killed by the antibiotic-loaded coating, in a simulated prosthesis-related interfacial gap. PLGA-gentamicin-HA-coatings prevented growth of bioluminescent staphylococci around a miniature-stem mounted in bacterially contaminated agar, as observed using bio-optical imaging. PLGA-gentamicin-HA-coated pins inserted in bacterially contaminated medullary canals in rabbits caused a statistically significant reduction in infection rates compared to HA-coated pins without gentamicin. Bone ingrowth to PLGA-gentamicin-HA-coated pins, in condylar defects of Beagle dogs was not impaired by the presence of the degradable, gentamicin-loaded coating. In conclusion, the PLGA-gentamicin-HA-coating constitutes an effective strategy for infection prophylaxis in cementless prostheses.

  7. Thermomolecular Orientation of Nonpolar Fluids

    NARCIS (Netherlands)

    Römer, F.; Bresme, F.; Muscatello, J.; Bedeaux, D.; Rubi, J.M.

    2012-01-01

    We investigate the response of molecular fluids to temperature gradients. Using nonequilibrium molecular dynamics computer simulations we show that nonpolar diatomic fluids adopt a preferred orientation as a response to a temperature gradient. We find that the magnitude of this thermomolecular orien

  8. Effect of Catechins, Green tea Extract and Methylxanthines in Combination with Gentamicin Against Staphylococcus aureus and Pseudomonas aeruginosa - Combination therapy against resistant bacteria -

    OpenAIRE

    Bibi Sedigheh Fazly Bazzaz; Sahar Sarabandi; Bahman Khameneh; Hossein Hosseinzadeh

    2016-01-01

    Objectives: Bacterial resistant infections have become a global health challenge and threaten the society’s health. Thus, an urgent need exists to find ways to combat resistant pathogens. One promising approach to overcoming bacterial resistance is the use of herbal products. Green tea catechins, the major green tea polyphenols, show antimicrobial activity against resistant pathogens. The present study aimed to investigate the effect of catechins, green tea extract, and methylxanthines in com...

  9. A prospective study of gentamicin ototoxicity

    DEFF Research Database (Denmark)

    Winkel, O; Hansen, M M; Kaaber-Bühler, Søren;

    1978-01-01

    Twenty patients were included in a prospective otoneurological study performed to assess the ototoxicity in gentamicin therapy. Gentamicin was administered intravenously, and the serum level was currently determined. Audiographic and electronystagmographic studies were carried out at the institut...

  10. Clinical Pharmacokinetics of Gentamicin in Neonates

    Directory of Open Access Journals (Sweden)

    Gian Maria Pacifici

    2017-03-01

    Full Text Available Gentamicin is a bactericidal aminoglycoside antibiotic, it inhibits the protein synthesis. Gentamicin is active against the majority of aerobic gram-negative bacilli such as Pseudomonas, Klebsiella and Escherichia coli. The gentamicin doses are 3 mg/kg once-daily for preterm newborns 35 weeks of gestation. The monitoring of gentamicin serum concentration is recommended when infants are treated for 48 hours or more. The gentamicin peak concentration must be at least 8 times the minimum inhibitory concentration (MIC to be bactericidal and the gentamicin trough concentration must be < 2 µg/ml to avoid ototoxicity and nephrotoxicity.Once-daily dosing of gentamicin (4 mg/kg, is preferred than twice-daily dose of 2.5 mg/kg gentamicin. A gentamicin loading dose (4 mg/kg, followed by once-daily dosing of 2.5 mg/kg yields safe and target range in neonates. An extended dosing interval of 48-hour (5 mg/kg gentamicin, was compared with twice-daily dose of 2.5 mg/kg gentamicin. Infants in the 48-hour interval and in the twice-daily achieved peak gentamicin concentrations of 9.43 µg/ml and 6.0 µg/ml, respectively, (p

  11. Gentamicin in vitro activity and tentative gentamicin interpretation criteria for the CLSI and calibrated dichotomous sensitivity disc diffusion methods for Neisseria gonorrhoeae.

    Science.gov (United States)

    Bala, Manju; Singh, Vikram; Philipova, Ivva; Bhargava, Aradhana; Chandra Joshi, Naveen; Unemo, Magnus

    2016-07-01

    XDR Neisseria gonorrhoeae imposes the threat of untreatable gonorrhoea. Gentamicin is considered for future treatment; however, no interpretation criteria for the CLSI and calibrated dichotomous sensitivity (CDS) disc diffusion (DD) techniques are available for N. gonorrhoeae. We investigated the in vitro gentamicin activity by MIC and DD methods, proposed DD breakpoints and determined DD ranges for 10 international quality control (QC) strains. Gentamicin susceptibility of 333 N. gonorrhoeae isolates, including 323 clinical isolates and 10 QC strains, was determined. MIC determination (Etest) and DD methods (CLSI and CDS) were performed. The relationship between MIC, inhibition zone diameter and annular radius was determined by linear regression analysis and the correlation coefficient (r) was calculated. Gentamicin MICs for the QC strains were within published ranges. Of the 323 clinical isolates, according to published breakpoints 75.9%, 23.5% and 0.6% were susceptible, intermediately susceptible and resistant, respectively. Based on error minimization with MICs of ≤4, 8-16 and ≥32 mg/L, breakpoints proposed are susceptible ≥16 mm, intermediately susceptible 13-15 mm and resistant ≤12 mm for the CLSI method and susceptible ≥6 mm, less susceptible 3-5 mm and resistant ≤2 mm for the CDS technique. Low resistance to gentamicin was identified and gentamicin might be a future treatment option for gonorrhoea. Tentative gentamicin zone breakpoints were defined for two DD methods and QC ranges for 10 international reference strains were established. Our findings suggest that in resource-poor settings where MIC testing is not a feasible option, the DD methods can be used to indicate gentamicin resistance. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  12. Thermomolecular orientation of nonpolar fluids.

    Science.gov (United States)

    Römer, Frank; Bresme, Fernando; Muscatello, Jordan; Bedeaux, Dick; Rubí, J Miguel

    2012-03-09

    We investigate the response of molecular fluids to temperature gradients. Using nonequilibrium molecular dynamics computer simulations we show that nonpolar diatomic fluids adopt a preferred orientation as a response to a temperature gradient. We find that the magnitude of this thermomolecular orientation effect is proportional to the strength of the temperature gradient and the degree of molecular anisotropy, as defined by the different size or mass of the molecular atomic sites. We show that the preferred orientation of the molecules follows the same trends observed in the Soret effect of binary mixtures. We argue this is a general effect that should be observed in a wide range of length scales.

  13. Gentamicin susceptibility in Escherichia coli related to the genetic background: problems with breakpoints

    DEFF Research Database (Denmark)

    Jakobsen, L.; Sandvang, D.; Jensen, Vibeke Frøkjær

    2007-01-01

    In total, 120 Escherichia coli isolates positive for one of the gentamicin resistance (GEN(R)) genes aac(3)-II, aac(3)-IV or ant(2 '')-I were tested for gentamicin susceptibility by the agar dilution method. Isolates positive for aac(3)-IV or ant(2 '')-I had an MIC distribution of 8-64 mg/L, wher...... by EUCAST and questions the breakpoint recommended by the CLSI (>= 16 mg/L)....

  14. Compound list: gentamicin [Open TG-GATEs

    Lifescience Database Archive (English)

    Full Text Available gentamicin GMC 00147 ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vitro/gentamic...in.Rat.in_vitro.Liver.zip ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Liver/Single/gentamic...at/in_vivo/Liver/Repeat/gentamicin.Rat.in_vivo.Liver.Repeat.zip ftp://ftp.bioscie...ncedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Kidney/Single/gentamicin.Rat.in_vivo.Kidney.Single.zip ftp...://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Kidney/Repeat/gentamicin.Rat.in_vivo.Kidney.Repeat.zip ...

  15. Evaluating synergy between marbofloxacin and gentamicin in Pseudomonas aeruginosa strains isolated from dogs with otitis externa.

    Science.gov (United States)

    Jerzsele, Ákos; Pásztiné-Gere, Erzsébet

    2015-03-01

    The aim of this study was to determine antimicrobial susceptibility of Pseudomonas aeruginosa strains to marbofloxacin and gentamicin, and investigate the possible synergistic, additive, indifferent or antagonistic effects between the two agents. P. aeruginosa strains can develop resistance quickly against certain antibiotics if used alone, thus the need emerges to find synergistic combinations. A total of 68 P. aeruginosa strains isolated from dogs were examined. In order to describe interactions between marbofloxacin and gentamicin the checkerboard microdilution method was utilized. The MICs (minimum inhibitory concentrations) for marbofloxacin and gentamicin were in the range 0.25-64 mg/L and 0.25-32 mg/L, respectively. The combination of marbofloxacin and gentamicin was more effective with a MIC range of 0.031-8 mg/L and a MIC90 of 1 mg/L, compared to 16 mg/L for marbofloxacin alone and 8 mg/L for gentamicin alone. The FIC (fractional inhibitory concentration) indices ranged from 0.0945 (pronounced synergy) to 1.0625 (indifference). Synergy between marbofloxacin and gentamicin was found in 33 isolates. The mean FIC index is 0.546, which represents a partial synergistic/additive effect close to the full synergy threshold. In vitro results indicate that marbofloxacin and gentamicin as partially synergistic agents may prove clinically useful in combination therapy against P. aeruginosa infections. Although marbofloxacin is not used in the human practice, the interactions between fluoroquinolones and aminoglycosides may have importance outside the veterinary field.

  16. Gentamicin removal in submerged fermentation using the novel fungal strain Aspergillus terreus FZC3

    Science.gov (United States)

    Liu, Yuanwang; Chang, Huiqing; Li, Zhaojun; Zhang, Cheng; Feng, Yao; Cheng, Dengmiao

    2016-10-01

    Social concern and awareness of the potential risk posed by environmental residues of antibiotics such as gentamicin in the development of antibiotic resistance genes have increased. The present study used laboratory-scale experiments to develop methods for gentamicin removal from the environment. A fungus, strain FZC3, which could remove gentamicin in submerged fermentation, was isolated from solid waste and sewage water from a gentamicin production factory. The fungus was identified as Aspergillus terreus by sequencing the PCR-amplified ITS fragments of its rRNA-coding genes and by its morphology. The gentamicin removal efficiency exceeded 95% by day 7 under optimized culture conditions. The results showed that both biosorption and biodegradation were involved. We speculated that Aspergillus terreus FZC3 absorbed gentamicin and subsequently degraded it. We also found that Aspergillus terreus FZC3 survived and maintained a high bioremediation efficiency over a wide pH range, indicating its potential for future use in the large-scale bioremediation of gentamicin.

  17. Is Penicillin plus Gentamicin Synergistic against Clinical Group B Streptococcus isolates?: A in-vitro Study.

    Directory of Open Access Journals (Sweden)

    Corinne Ruppen

    2016-10-01

    Full Text Available Group B Streptococcus (GBS is increasingly causing invasive infections in nonpregnant adults. Elderly patients and those with comorbidities are at increased risk. On the basis of previous studies focusing on neonatal infections, penicillin plus gentamicin is recommended for infective endocarditis (IE and periprosthetic joint infections (PJI in adults. The purpose of this study was to investigate whether a synergism with penicillin and gentamicin is present in GBS isolates that caused IE and PJI. We used 5 GBS isolates, two clinical strains and three control strains, including one displaying high-level gentamicin resistance (HLGR. The results from the checkerboard and time-kill assays (TKAs were compared. For TKAs, antibiotic concentrations for penicillin were 0.048 and 0.2 mg/L, and for gentamicin 4 mg/L or 12.5 mg/L. In the checkerboard assay, the median fractional inhibitory concentration indices (FICIs of all isolates indicated indifference. TKAs for all isolates failed to demonstrate synergism with penicillin 0.048 or 0.2 mg/L, irrespective of gentamicin concentrations used. Rapid killing was seen with penicillin 0.048 mg/L plus either 4 mg/L or 12.5 mg/L gentamicin, from 2 h up to 8 h hours after antibiotic exposure. TKAs with penicillin 0.2 mg/L decreased the starting inoculum below the limit of quantification within 4 h to 6 h, irrespective of the addition of gentamicin. Fast killing was seen with penicillin 0.2 mg/L plus 12.5 mg/L gentamicin within the first 2 h. Our in vitro results indicate that the addition of gentamicin to penicillin contributes to faster killing at low penicillin concentrations, but only within the first few hours. Twenty-four hours after antibiotic exposure, PEN alone was bactericidal and synergism was not seen.

  18. Is Penicillin Plus Gentamicin Synergistic against Clinical Group B Streptococcus isolates?: An In vitro Study.

    Science.gov (United States)

    Ruppen, Corinne; Lupo, Agnese; Decosterd, Laurent; Sendi, Parham

    2016-01-01

    Group B Streptococcus (GBS) is increasingly causing invasive infections in non-pregnant adults. Elderly patients and those with comorbidities are at increased risk. On the basis of previous studies focusing on neonatal infections, penicillin plus gentamicin is recommended for infective endocarditis (IE) and periprosthetic joint infections (PJI) in adults. The purpose of this study was to investigate whether a synergism with penicillin and gentamicin is present in GBS isolates that caused IE and PJI. We used 5 GBS isolates, two clinical strains and three control strains, including one displaying high-level gentamicin resistance (HLGR). The results from the checkerboard and time-kill assays (TKAs) were compared. For TKAs, antibiotic concentrations for penicillin were 0.048 and 0.2 mg/L, and for gentamicin 4 mg/L or 12.5 mg/L. In the checkerboard assay, the median fractional inhibitory concentration indices (FICIs) of all isolates indicated indifference. TKAs for all isolates failed to demonstrate synergism with penicillin 0.048 or 0.2 mg/L, irrespective of gentamicin concentrations used. Rapid killing was seen with penicillin 0.048 mg/L plus either 4 mg/L or 12.5 mg/L gentamicin, from 2 h up to 8 h hours after antibiotic exposure. TKAs with penicillin 0.2 mg/L decreased the starting inoculum below the limit of quantification within 4-6 h, irrespective of the addition of gentamicin. Fast killing was seen with penicillin 0.2 mg/L plus 12.5 mg/L gentamicin within the first 2 h. Our in vitro results indicate that the addition of gentamicin to penicillin contributes to faster killing at low penicillin concentrations, but only within the first few hours. Twenty-four hours after antibiotic exposure, PEN alone was bactericidal and synergism was not seen.

  19. Gentamicin concentrations in human subcutaneous tissue

    DEFF Research Database (Denmark)

    Lorentzen, Hanne; Kallehave, Finn Lasse; Kolmos, Hans Jørn Jepsen

    1996-01-01

    in human subcutaneous adipose tissue by a microdialysis technique. Seven healthy young volunteers each had four microdialysis probes placed in the fat (subcutaneous) layer of the abdominal skin. After the administration of a 240-mg gentamicin intravenous bolus, consecutive measurements of the drug...... of the gentamicin concentration in human subcutaneous tissue. In this adipose tissue, the peak concentrations of gentamicin were approximately seven times the MIC for Pseudomonas aeruginosa and 33 times the MIC for Staphylococcus aureus after the administration of an intravenous bolus of 240 mg, indicating......Wound infections frequently originate from the subcutaneous tissue. The effect of gentamicin in subcutaneous tissue has, however, normally been evaluated from concentrations in blood or wound fluid. The aim of the present study was to investigate the pharmacokinetic properties of gentamicin...

  20. Oral Gentamicin Gut Decontamination for Prevention of KPC-Producing Klebsiella pneumoniae Infections: Relevance of Concomitant Systemic Antibiotic Therapy

    Science.gov (United States)

    Tascini, Carlo; Sbrana, Francesco; Flammini, Sarah; Tagliaferri, Enrico; Arena, Fabio; Leonildi, Alessandro; Ciullo, Ilaria; Amadori, Francesco; Di Paolo, Antonello; Ripoli, Andrea; Lewis, Russell; Rossolini, Gian Maria

    2014-01-01

    Gut colonization represents the main source for KPC-producing Klebsiella pneumoniae (KPC-Kp) epidemic dissemination. Oral gentamicin, 80 mg four times daily, was administered to 50 consecutive patients with gut colonization by gentamicin-susceptible KPC-Kp in cases of planned surgery, major medical intervention, or need for patient transfer. The overall decontamination rate was 68% (34/50). The median duration of gentamicin treatment was 9 days (interquartile range, 7 to 15 days) in decontaminated patients compared to 24 days (interquartile range, 20 to 30 days) in those with persistent colonization (P < 0.001). In the six-month period of follow-up, KPC-Kp infections were documented in 5/34 (15%) successfully decontaminated patients compared to 12/16 (73%) persistent carriers (P < 0.001). The decontamination rate was 96% (22/23) in patients receiving oral gentamicin only, compared to 44% (12/27) of those treated with oral gentamicin and concomitant systemic antibiotic therapy (CSAT) (P < 0.001). The multivariate analysis confirmed CSAT and KPC-Kp infection as the variables associated with gut decontamination. In the follow-up period, KPC-Kp infections were documented in 2/23 (9%) of patients treated with oral gentamicin only and in 15/27 (56%) of those also receiving CSAT (P = 0.003). No difference in overall death rate between different groups was documented. Gentamicin-resistant KPC-Kp strains were isolated from stools of 4/16 persistent carriers. Peak gentamicin blood levels were below 1 mg/liter in 12/14 tested patients. Oral gentamicin was shown to be potentially useful for gut decontamination and prevention of infection due to KPC-Kp, especially in patients not receiving CSAT. The risk of emergence of gentamicin-resistant KPC-Kp should be considered. PMID:24419337

  1. Intramammary treatment with gentamicin in lactating cows with clinical and subclinical mastitis

    Directory of Open Access Journals (Sweden)

    Thamires Martins

    2016-04-01

    Full Text Available Abstract The study evaluated the microbiological profile of milk samples collected before and after mastitis treatment with gentamicin and investigated biofilms production and antimicrobial susceptibility of Staphylococcus spp. isolated. The presence of gentamicin residues in milk after the recommended withdrawal period was also evaluated. Antimicrobial residues were analyzed by Delvotest® SP NT over a period of 12 days beginning after 24 hours the last gentamicin application. Some of Staphylococcus spp. isolates were biofilm producers (19.05%. Staphylococcus spp. showed high levels of resistance to neomycin (16.95%, penicillin G (10.17%, and ampicillin (10.17%. Multidrug resistance to all antibiotics tested was observed in 1.69% of the Staphylococcus spp. isolates. Among 1440 mammary quarter milk samples 24.95% presented gentamicin residues after the withdrawal period. Gentamicin residues were also detected in 3.8% of samples from calibrated glass recorder jar (n=383 4.1 days after treatment. The indiscriminate use of antibiotics may lead to the emergence of multidrug-resistant strains as well as increasing the risk of presence of residues of these drugs in milk. These problems affect the milk quality and may become a public health problem.

  2. A prospective study of gentamicin ototoxicity

    DEFF Research Database (Denmark)

    Winkel, O; Hansen, M M; Kaaber-Bühler, Søren

    2010-01-01

    Twenty patients were included in a prospective otoneurological study performed to assess the ototoxicity in gentamicin therapy. Gentamicin was administered intravenously, and the serum level was currently determined. Audiographic and electronystagmographic studies were carried out at the institut......Twenty patients were included in a prospective otoneurological study performed to assess the ototoxicity in gentamicin therapy. Gentamicin was administered intravenously, and the serum level was currently determined. Audiographic and electronystagmographic studies were carried out...... at the institution and discontinuation of the treatment and again a few weeks later. Ten patients exhibited ototoxic actions, predominantly cochlear, 4 of the cases being fully reversible. Two patients developed severe hearing loss, associated in one with bilateral extinction of vestibular function. Low serum levels...... of gentamicin did not rule out the possiblity of ototoxicity. These results urge the continuing of prospective studies and indicate that gentamicin should be used only as a link in the primary treatment of severe infection or in cases in which other, less toxic agents have failed....

  3. Chitosan improves anti-biofilm efficacy of gentamicin through facilitating antibiotic penetration.

    Science.gov (United States)

    Mu, Haibo; Guo, Fan; Niu, Hong; Liu, Qianjin; Wang, Shunchun; Duan, Jinyou

    2014-12-03

    Antibiotic overuse is one of the major drivers in the generation of antibiotic resistant "super bugs" that can potentially cause serious effects on health. In this study, we reported that the polycationic polysaccharide, chitosan could improve the efficacy of a given antibiotic (gentamicin) to combat bacterial biofilms, the universal lifestyle of microbes in the world. Short- or long-term treatment with the mixture of chitosan and gentamicin resulted in the dispersal of Listeria monocytogenes (L. monocytogenes) biofilms. In this combination, chitosan with a moderate molecular mass (~13 kDa) and high N-deacetylation degree (~88% DD) elicited an optimal anti-biofilm and bactericidal activity. Mechanistic insights indicated that chitosan facilitated the entry of gentamicin into the architecture of L. monocytogenes biofilms. Finally, we showed that this combination was also effective in the eradication of biofilms built by two other Listeria species, Listeria welshimeri and Listeria innocua. Thus, our findings pointed out that chitosan supplementation might overcome the resistance of Listeria biofilms to gentamicin, which might be helpful in prevention of gentamicin overuse in case of combating Listeria biofilms when this specific antibiotic was recommended.

  4. Chitosan Improves Anti-Biofilm Efficacy of Gentamicin through Facilitating Antibiotic Penetration

    Directory of Open Access Journals (Sweden)

    Haibo Mu

    2014-12-01

    Full Text Available Antibiotic overuse is one of the major drivers in the generation of antibiotic resistant “super bugs” that can potentially cause serious effects on health. In this study, we reported that the polycationic polysaccharide, chitosan could improve the efficacy of a given antibiotic (gentamicin to combat bacterial biofilms, the universal lifestyle of microbes in the world. Short- or long-term treatment with the mixture of chitosan and gentamicin resulted in the dispersal of Listeria monocytogenes (L. monocytogenes biofilms. In this combination, chitosan with a moderate molecular mass (~13 kDa and high N-deacetylation degree (~88% DD elicited an optimal anti-biofilm and bactericidal activity. Mechanistic insights indicated that chitosan facilitated the entry of gentamicin into the architecture of L. monocytogenes biofilms. Finally, we showed that this combination was also effective in the eradication of biofilms built by two other Listeria species, Listeria welshimeri and Listeria innocua. Thus, our findings pointed out that chitosan supplementation might overcome the resistance of Listeria biofilms to gentamicin, which might be helpful in prevention of gentamicin overuse in case of combating Listeria biofilms when this specific antibiotic was recommended.

  5. Depression of vitamin B6 levels due to gentamicin.

    Science.gov (United States)

    Weir, M R; Keniston, R C; Enriquez, J I; McNamee, G A

    1990-06-01

    The renal toxicity of gentamicin is altered by dietary protein modifications, bicarbonate and acetazolamide administration, magnesium supplementation, polyaspartic acid, piperacillin, hypercalcemia and calcium channel blockers. Renal tissue gentamicin levels have an undetermined role. Reduction of renal pyridoxal 5'-phosphate (PLP- by gentamicin has been shown, as has protection from nephrotoxicity by administration of vitamin B6. To explore an interaction between gentamicin and vitamin B6, gentamicin (5 mg/kg) was given to rabbits by ip injection, with either pyridoxine (10 mg) or isovolemic saline for 3 weeks. There was not a difference between gentamicin levels for animals given gentamicin and pyridoxine versus those given gentamicin and saline. Gentamicin administration led to a 47% fall (p = .0001) in plasma PLP levels. Three days after the last gentamicin administration, the animals maintained a 32% decrease from the pre-gentamicin baseline values (p = 0.02). When pyridoxine was administered concurrently with gentamicin, the PLP rise of 49% was significant (p = 0.001). The mean level after the study (6%) was not significantly lower than baseline (p = .6). We believe that gentamicin interfers with vitamin B6 metabolism, but that vitamin B6 status does not affect levels of gentamicin. A number of drugs affect B6 levels, creating the potential for hypovitaminosis B6 to be an important mechanism of drug-drug interaction in seriously ill patients, particularly in sick newborns or the elderly with lower average PLP levels.

  6. Birefringent non-polarizing thin film design

    Institute of Scientific and Technical Information of China (English)

    QI Hongji; HONG Ruijin; HE Hongbo; SHAO Jianda; FAN Zhengxiu

    2005-01-01

    In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations, which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin film over visible spectral region are obtained at oblique incidence.

  7. [Amoxicillin and clavulanic acid versus amoxicillin plus gentamicin in the empirical initial treatment of urinary tract infections in hospitalized patients].

    Science.gov (United States)

    Verzasconi, R; Rodoni, P; Monotti, R; Marone, C; Mombelli, G

    1995-08-19

    We compared the fixed combination amoxicillin plus clavulanic acid with that of amoxicillin plus gentamicin in the empirical initial treatment of severe urinary tract infections. The study included 87 hospitalized patients (51 women and 36 men, mean age 58 +/- 22 years) with acute uncomplicated pyelonephritis (n = 48) or with complicated urinary tract infections (n = 39). 80 patients (92%) had fever and 31 patients (36%) positive blood cultures. 45 patients were randomly assigned to amoxicillin plus clavulanic acid and 42 to amoxicillin plus gentamicin. Overall, 18 patients (21%) were infected with organisms resistant in vitro to amoxicillin plus clavulanic acid, whereas no pathogen was isolated with resistance to amoxicillin plus gentamicin (p amoxicillin plus gentamicin (p amoxicillin plus gentamicin group. Although the in-vitro resistance did not result in a lower clinical efficacy of amoxicillin plus clavulanic acid compared to amoxicillin plus gentamicin in our relatively small sample of patients, the data indicate that the antimicrobial activity of amoxicillin plus clavulanic acid is inadequate to cover the spectrum of causative agents in hospitalized patients with pyelonephritis or complicated urinary tract infections. Amoxicillin plus clavulanic acid should therefore not be used in the initial empirical treatment of these infections.

  8. Complete genome sequences of multidrug-resistant Campylobacter jejuni 14980A (turkey feces) and Campylobacter coli 14983A (housefly from turkey farm), harboring a novel gentamicin resistance mobile element.

    Science.gov (United States)

    Multidrug resistance (MDR) in foodborne pathogens is a major food safety and public health issue. Here we describe whole-genome sequences of two MDR strains of Campylobacter jejuni and Campylobacter coli from turkey feces and a housefly in a turkey farm. Both strains harbor a novel chromosomal genta...

  9. Bactericidal Effect of Pterostilbene Alone and in Combination with Gentamicin against Human Pathogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Wee Xian Lee

    2017-03-01

    Full Text Available The antibacterial activity of pterostilbene in combination with gentamicin against six strains of Gram-positive and Gram-negative bacteria were investigated. The minimum inhibitory concentration and minimum bactericidal concentration of pterostilbene were determined using microdilution technique whereas the synergistic antibacterial activities of pterostilbene in combination with gentamicin were assessed using checkerboard assay and time-kill kinetic study. Results of the present study showed that the combination effects of pterostilbene with gentamicin were synergistic (FIC index < 0.5 against three susceptible bacteria strains: Staphylococcus aureus ATCC 25923, Escherichia coli O157 and Pseudomonas aeruginosa 15442. However, the time-kill study showed that the interaction was indifference which did not significantly differ from the gentamicin treatment. Furthermore, time-kill study showed that the growth of the tested bacteria was completely attenuated with 2 to 8 h treatment with 0.5 × MIC of pterostilbene and gentamicin. The identified combinations could be of effective therapeutic value against bacterial infections. These findings have potential implications in delaying the development of bacterial resistance as the antibacterial effect was achieved with the lower concentrations of antibacterial agents.

  10. Bactericidal Effect of Pterostilbene Alone and in Combination with Gentamicin against Human Pathogenic Bacteria.

    Science.gov (United States)

    Lee, Wee Xian; Basri, Dayang Fredalina; Ghazali, Ahmad Rohi

    2017-03-17

    The antibacterial activity of pterostilbene in combination with gentamicin against six strains of Gram-positive and Gram-negative bacteria were investigated. The minimum inhibitory concentration and minimum bactericidal concentration of pterostilbene were determined using microdilution technique whereas the synergistic antibacterial activities of pterostilbene in combination with gentamicin were assessed using checkerboard assay and time-kill kinetic study. Results of the present study showed that the combination effects of pterostilbene with gentamicin were synergistic (FIC index < 0.5) against three susceptible bacteria strains: Staphylococcus aureus ATCC 25923, Escherichia coli O157 and Pseudomonas aeruginosa 15442. However, the time-kill study showed that the interaction was indifference which did not significantly differ from the gentamicin treatment. Furthermore, time-kill study showed that the growth of the tested bacteria was completely attenuated with 2 to 8 h treatment with 0.5 × MIC of pterostilbene and gentamicin. The identified combinations could be of effective therapeutic value against bacterial infections. These findings have potential implications in delaying the development of bacterial resistance as the antibacterial effect was achieved with the lower concentrations of antibacterial agents.

  11. 21 CFR 522.1044 - Gentamicin.

    Science.gov (United States)

    2010-04-01

    ... treatment of infections of urinary tract (cystitis, nephritis), respiratory tract (tonsillitis, pneumonia... treatment of infections of urinary tract (cystitis, nephritis), respiratory tract (pneumonitis, pneumonia... food for at least 9 weeks after treatment. (3) Chickens—(i) Amount. 0.2 milligram of gentamicin per 0.2...

  12. Silica-Gentamicin Nanohybrids: Synthesis and Antimicrobial Action

    Directory of Open Access Journals (Sweden)

    Dina Ahmed Mosselhy

    2016-03-01

    Full Text Available Orthopedic applications commonly require the administration of systemic antibiotics. Gentamicin is one of the most commonly used aminoglycosides in the treatment and prophylaxis of infections associated with orthopedic applications, but gentamicin has a short half-life. However, silica nanoparticles (SiO2 NPs can be used as elegant carriers for antibiotics to prolong their release. Our goal is the preparation and characterization of SiO2-gentamicin nanohybrids for their potential antimicrobial administration in orthopedic applications. In vitro gentamicin release profile from the nanohybrids (gentamicin-conjugated SiO2 NPs prepared by the base-catalyzed precipitation exhibited fast release (21.4% during the first 24 h and further extension with 43.9% release during the five-day experiment. Antimicrobial studies of the SiO2-gentamicin nanohybrids versus native SiO2 NPs and free gentamicin were performed against Bacillus subtilis (B. subtilis, Pseudomonas fluorescens (P. fluorescens and Escherichia coli (E. coli. SiO2-gentamicin nanohybrids were most effective against B. subtilis. SiO2 NPs play no antimicrobial role. Parallel antimicrobial studies for the filter-sterilized gentamicin were performed to assess the effect of ultraviolet (UV-irradiation on gentamicin. In summary, the initial fast gentamicin release fits the need for high concentration of antibiotics after orthopedic surgical interventions. Moreover, the extended release justifies the promising antimicrobial administration of the nanohybrids in bone applications.

  13. An Antioxidant Screen Identifies Candidates for Protection of Cochlear Hair Cells from Gentamicin Toxicity

    Directory of Open Access Journals (Sweden)

    Volker Noack

    2017-08-01

    Full Text Available Reactive oxygen species are important elements in ototoxic damage to hair cells (HCs, appearing early in the damage process. Higher levels of natural antioxidants are positively correlated with resistance to ototoxins and many studies have shown that exogenous antioxidants can protect HCs from damage. While a very wide variety of antioxidants with different characteristics and intracellular targets exist, most ototoxicity studies have focused upon one or a few well-characterized compounds. Relatively little research has attempted to determine the comparative efficacy of large variety of different antioxidants. This has been in part due to the lack of translation between cell culture and in vivo measures of efficacy. To circumvent this limitation, we used an in vitro assay based on micro-explants from the basal and middle turns of the neonatal mouse organ of Corti to screen a commercial redox library of diverse antioxidant compounds for their ability to protect mammalian HCs from a high dose of the ototoxic antibiotic gentamicin. The library included several antioxidants that have previously been studied as potential treatments for HC damage, as well as many antioxidants that have never been applied to ototoxicity. The micro-explants were treated with 200 μM gentamicin alone, gentamicin plus one of three dosages of a redox compound, the highest dosage of compound alone, or were untreated. HC counts were determined before the gentamicin insult and at 1, 2, and 3 days afterward to evaluate the HC survival. From a total of 81 antioxidant compounds, 13 exhibited significant protection of HCs. These included members of a variety of antioxidant classes with several novel antioxidants, not previously tested on HCs, appearing to alleviate the damaging gentamicin effect. Some compounds previously shown to be protective of HCs were correspondingly protective in this in vitro screen, while others were not. Finally, one of the three pro-oxidant compounds

  14. [A clinical study on gentamicin in the field of surgery].

    Science.gov (United States)

    Fujimoto, M; Ueda, T; Hirao, S; Sakai, K

    1976-03-01

    Gentamicin (GM), one of the amino-glucosides, was administered intramuscularly to 27 patients with Pseudomonas and/or other antibiotics resistant infections. The clinical evaluation of the results obtained was classified excellent in 1 case good 6, fair 8, none 11 and indeterminate 1, the effectiveness accounting for 57.7 percent. Satisfactory results were noted in wound infections, peritonitis and urinary tract infections. Among untoward side effects, an elevation in GOT and GPT values was observed in 6 cases, an elevation of BUN value in 1, proteinuria in 1 and hematuria in 1. However, it is difficult to conclude that those side effects were attributable to GM itself because blood transfusion or combined therapy with anti-cancer agents was conducted in these cases during the GM therapy.

  15. Gentamicin Nephrotoxicity in Subclinical Renal Disease.

    Science.gov (United States)

    Frazier, Donita L.

    The purpose of the present study was to examine the pharmacokinetic disposition of gentamicin and to define the mechanisms which predispose to nephrotoxicity in subclinical renal disease. Subtotally nephrectomized beagle dogs were used as a model for human beings with compromised renal function secondary to a reduced number of functional nephrons. Using ultrastructural morphometry, light microscopy and clinical chemistry data, the model was defined and the nephrotoxic responses of intact dogs administered recommended doses of drug were compared to the response of subtotally nephrectomized dogs administered reduced doses based on each animal's clearance of drug. Lysosomal and mitochondrial morphometric changes suggested mechanisms for increased sensitivity. To determine if increased sensitivity in this model was dependent on altered serum concentrations, variable rate infusions based on individual pharmacokinetic disposition of drug were administered using computer-driven infusion pumps. Identical serum concentration-time profiles were achieved in normal dogs and subtotally nephrectomized dogs, however, toxicity was significantly greater in nephrectomized dogs. The difference in the nephrotoxic response was characterized by administering supratherapeutic doses of drug to dogs. Nephrectomized dogs given a recommended dose of gentamicin became oliguric during the second week of treatment and increasingly uremic after withdrawal of drug. In contrast, intact dogs administered 2 times the recommended dose of gentamicin become only slightly polyuric during week 4 of treatment. The need to individualize dosage regimens based on drug clearance and not serum creatinine nor creatinine clearance alone was substantiated by describing the pharmacokinetic disposition of gentamicin in spontaneously occurring disease states. Four individualized dosage regimens with differing predicted efficacy were then administered to nephrectomized dogs to determine their relative nephrotoxic

  16. Spherical gold nanoparticles and gold nanorods for the determination of gentamicin

    Science.gov (United States)

    Miranda-Andrades, Jarol R.; Pérez-Gramatges, Aurora; Pandoli, Omar; Romani, Eric C.; Aucélio, Ricardo Q.; da Silva, Andrea R.

    2017-02-01

    Gentamicin is an antibiotic indicated to treat mastitis in dairy cattle and for the treatment of bacterial resistance in the context of hospital infections. The effect caused by gentamicin on the optical properties of gold nanoparticles aqueous dispersions were used to develop quantitative methods to determine this antibiotic. Two different aqueous dispersions, one containing spherical Au nanoparticles (AuNPs) and the other containing Au nanorods (AuNRs), had their conditions adjusted to enable a stable and sensitive response towards gentamicin. The use of AuNPs, with measurement at 681 nm of the rising coupling plasmon band, enabled a limit of detection (LOD) of 0.4 ng mL- 1 (0.02 ng absolute LOD), ten times lower than the one achieved by measuring the decreasing of the longitudinal surface plasmon resonance band (at 662 nm). The linear analytical response of AuNPs measured at 681 nm did not require rationing of signal values to correct for linearity. Stability of the analytical response resulted in intermediary precision below 2%. No significant interference was imposed by excipients traditionally present in injectable solutions for veterinary use. Percent recoveries obtained in such formulations were between 94.5 and 98.2% regardless the existence of any difference in the proportion of the compounds known as gentamicin (C1, C1a and C2) in standard and in the samples. The method requires no derivatization with toxic reagents as usually is required in other spectroscopic approaches.

  17. Teratogenic effects of Gentamicin on skeletal system of rat fetuses

    Directory of Open Access Journals (Sweden)

    Marzban H

    1999-09-01

    Full Text Available Gentamicin was evaluated for developmental toxicity in pregnant Sprague-Dawley rat. Gentamicin was administered subcutaneously on days 6-15 gestation at dose of 100 mg/kg. On gestation day 21, all live fetuses were examined for external and skeletal malformations and variations. Increased resorptions and dead fetuses, and reduced fetal body weight were observed at dose of 100 mg/kg. Gentamicin caused severe skeletal anomalies, such as: wavy ribs, incomplete ossification of sternebrae, tail vertebra, metacarpus, metatarsus and calvaria. These results indicate the nature and extent of embryotoxicity and teratogenicity of gentamicin in Sprague-Dawley rats.

  18. Flavocoxid attenuates gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    El-Kashef, Dalia H; El-Kenawi, Asmaa E; Suddek, Ghada M; Salem, Hatem A

    2015-12-01

    Gentamicin is a widely used antibiotic against serious and life-threatening infections; however, its usefulness is limited by the development of nephrotoxicity. The present study was designed to determine whether flavocoxid has a protective effect against gentamicin-induced nephrotoxicity in rats. For this purpose, we quantitatively evaluated gentamicin-induced renal structural and functional alterations using histopathological and biochemical approaches. Furthermore, the effect of flavocoxid on gentamicin induced hypersensitivity of urinary bladder rings to acetylcholine (ACh) was determined. Twenty-four male Wistar albino rats were randomly divided into three groups, namely control, gentamicin (100 mg/kg, i.p.) and gentamicin plus flavocoxid (20 mg/kg, orally). At the end of the study, all rats were sacrificed and then blood, urine samples and kidneys were collected for further analysis. Gentamicin administration caused a severe nephrotoxicity which was evidenced by an elevated renal somatic index (RSI), serum creatinine, blood urea nitrogen, serum lactate dehydrogenase, and protein in urine with a concomitant reduction in serum albumin and normalized creatinine clearance value as compared with the controls. Moreover, a significant increase in renal contents of malondialdehyde, myeloperoxidase, and tumor necrosis factor-alpha with a significant decrease in renal reduced glutathione and superoxide dismutase activities was detected upon gentamicin administration together with increasing the sensitivity of isolated urinary bladder rings to ACh. Exposure to gentamicin induced necrosis of renal tubular epithelial cells. Flavocoxid protected kidney tissue against the oxidative damage and the nephrotoxic effect caused by gentamicin treatment. In addition, flavocoxid significantly reduced the responses of isolated bladder rings to ACh. The results from our study indicate that flavocoxid supplement attenuates gentamicin-induced renal injury via the amelioration of

  19. Effects of gentamicin monotherapy for the initial treatment of community-onset complicated non-obstructive acute pyelonephritis due to Enterobacteriaceae in elderly and non-elderly women.

    Science.gov (United States)

    Wie, S-H; Kim, H W; Chang, U-I

    2014-11-01

    Aminoglycosides may serve as fluoroquinolone-sparing or cephalosporin-sparing agents if the clinical effectiveness of aminoglycoside monotherapy is demonstrated. The purposes of this study were to investigate the clinical efficacy of gentamicin as an initial empirical antimicrobial agent and to evaluate the effects of gentamicin resistance on clinical outcomes in women with complicated non-obstructive acute pyelonephritis (APN). Medical records of 1066 women with a diagnosis of APN were reviewed retrospectively. We enrolled 275 women with community-onset complicated non-obstructive APN due to Enterobacteriaceae who received gentamicin as their initial antibiotic. Of these 275 patients, 43 had gentamicin-resistant (GM-R) Enterobacteriaceae APN, and 232 had gentamicin-susceptible (GM-S) Enterobacteriaceae APN. The early clinical success rates were 67.4% (29/43) versus 89.7% (208/232) at 72 h in the GM-R versus the GM-S groups (p 0.001). The overall clinical cure rate was 100% (43/43) and 98.7% (229/232) in the GM-R and GM-S groups, respectively. The duration of hospital stay was significantly longer in the elderly, although there were no significant differences in the rates of early clinical success, final clinical cure, mortality, and time to fever clearance between the elderly and non-elderly groups. Resistance of Enterobacteriaceae to gentamicin, haematuria and serum C-reactive protein level≥20 mg/dL were independently associated with early clinical failure. Gentamicin can be an effective initial antibiotic option for empirical therapy in women with community-onset complicated APN who do not need urological interventional procedures. The use of gentamicin may contribute to a reduction of fluoroquinolone or broad-spectrum cephalosporin use in the treatment of complicated APN.

  20. Pressure treatment versus gentamicin for Meniere's disease.

    Science.gov (United States)

    Odkvist, L

    2001-01-01

    Ménière's disease may be treated in different ways. After obtaining a case history and performing auditory and vestibular tests the diagnosis should be obvious. In terms of treatment, the first steps are to provide the patient with information, institute a low-salt diet and regulate internal medical disorders. The next step is pharmacological treatment using diuretics, betahistine and other drugs. Local pulsated pressure treatment in the ear canal has been used in a placebo-controlled study and showed significant improvement, primarily of vertigo, but also in terms of tinnitus and hearing. Hence, this form of treatment can be used in some phases of the disease. In more severe cases gentamicin treatment has proved successful; in the present study, vertigo was cured in all but 3 of 35 patients. On average, no extra hearing loss was caused: however, one ear became deaf, some ears showed improvement and some ears showed a certain degree of hearing loss. In cases of escalation of Ménière's disease, pressure treatment should be used initially, followed by gentamicin. These two methods of treatment are not in competition as they are used to treat different stages of the disease.

  1. Patients’ safety: is there a systemic release of gentamicin by gentamicin-coated tibia nails in clinical use?

    Science.gov (United States)

    Moghaddam, Arash; Graeser, Viola; Westhauser, Fabian; Dapunt, Ulrike; Kamradt, Till; Woerner, Stefan M; Schmidmaier, Gerhard

    2016-01-01

    Introduction Osteitis is one of the most serious complications in orthopedic surgery. Expert Tibia Nail (ETN) PROtect™ coated with a biodegradable layer of gentamicin-laden polymer was developed for prophylaxis of osteomyelitis. In systemic administration, gentamicin has only a small therapeutic index and serious side effects; it is potentially nephrotoxic as well as ototoxic. It is not yet known if relevant gentamicin concentrations are released into the systemic circulation after implantation of gentamicin-coated nails. In order to evaluate the patients’ risks profiles and increase patient safety, we measured gentamicin levels in pre- and postoperative serum samples of patients undergoing implantation of ETN PROtect. Methods Twenty-five patients who received ETN PROtect between March 2012 and August 2014 were included in this study. Collection of blood samples occurred before the operation, at weeks 1–4, 3 and 6 months, and up to 1 year after the implantation. Measurement of gentamicin levels in serum samples was performed at the central laboratory of Heidelberg University Hospital. Additionally, laboratory parameters, C-reactive protein, leukocyte number, urea and creatinine concentrations were analyzed in routine controls before and after operating and assessed for systemic side effects. Results Over the course of this prospective observational study, we were able to determine that gentamicin-coated nails do not release gentamicin into the systemic circulation above the lowest detectable level of 0.2 mg/dL. There were slight increases in the mean inflammation and renal retention markers, but no gentamicin-associated side effects could be linked to implantation. Furthermore, no allergic reactions could be detected during our study. Conclusion Our findings suggest that there is no relevant release of gentamicin into the systemic circulation causing a systemic effect, and serious side effects due to gentamicin-coated tibia nails should not be feared

  2. Enzymuria in neonates receiving continuous intravenous infusion of gentamicin

    DEFF Research Database (Denmark)

    Colding, H; Brygge, K; Brendstrup, L;

    1992-01-01

    with non-treatment periods in the same newborn infant (33 infants). The same tendency applied to AAP. Newborn infants receiving continuous intravenous infusion of gentamicin were not found to be at greater risk of nephrotoxicity than those receiving intermittent gentamicin treatment, using NAG and AAP...

  3. Gentamicin Exposure and Sensorineural Hearing Loss in Preterm Infants.

    Directory of Open Access Journals (Sweden)

    Aline Fuchs

    Full Text Available To evaluate the impact of gentamicin exposure on sensorineural hearing loss (SNHL in very low birth weight (VLBW infants.Exposure to gentamicin was determined in infants born between 1993 and 2010 at a gestational age < 32 weeks and/or with a birthweight < 1500 g, who presented with SNHL during the first 5 years of life. For each case, we selected two controls matched for gender, gestational age, birthweight, and year of birth.We identified 25 infants affected by SNHL, leading to an incidence of SNHL of 1.58% in our population of VLBW infants. The proportion of infants treated with gentamicin was 76% in the study group and 70% in controls (p = 0.78. The total cumulated dose of gentamicin administered did not differ between the study group (median 10.2 mg/kg, Q1-Q3 1.6-13.2 and the control group (median 7.9 mg/kg, Q1-Q3 0-12.8, p = 0.47. The median duration of gentamicin treatment was 3 days both in the study group and the control group (p = 0.58. Maximum predicted trough serum levels of gentamicin, cumulative area under the curve and gentamicin clearance were not different between cases and controls.The impact of gentamicin on SNHL can be minimized with treatments of short duration, monitoring of blood levels and dose adjustment.

  4. Preliminary study on synergistic combinations of raw honey with gentamicin against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa of veterinary origin

    Institute of Scientific and Technical Information of China (English)

    MoussaAhmed; Baghdad Khiati; SaadAissat; Noureddine Djebli

    2015-01-01

    Objective: To search for further synergistic combinations of gentamicin and raw honey that might have potential in treating wounds. Methods: The antibacterial activity and synergistic interaction of raw honey and gentamicin was assessed by using agar well diffusion method. Two Gram-negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 2154) bacteria were selected for antibacterial activity assay. The cultures of bacteria were maintained in their appropriate agar slants at 4 °C throughout the study and used as stock cultures. Results: Raw honey and gentamicin interacted synergistically to inhibit Escherichia coli and Pseudomonas aeruginosa. Conclusions: These results suggest that combinations of raw honey and gentamicin have therapeutic benefits in prophylaxis of infections caused by multidrug-resistant Gram-negative bacilli.

  5. EDITORIAL: Non-polar and semipolar nitride semiconductors Non-polar and semipolar nitride semiconductors

    Science.gov (United States)

    Han, Jung; Kneissl, Michael

    2012-02-01

    Throughout the history of group-III-nitride materials and devices, scientific breakthroughs and technological advances have gone hand-in-hand. In the late 1980s and early 1990s, the discovery of the nucleation of smooth (0001) GaN films on c-plane sapphire and the activation of p-dopants in GaN led very quickly to the realization of high-brightness blue and green LEDs, followed by the first demonstration of GaN-based violet laser diodes in the mid 1990s. Today, blue InGaN LEDs boast record external quantum efficiencies exceeding 80% and the emission wavelength of the InGaN-based laser diode has been pushed into the green spectral range. Although these tremenduous advances have already spurred multi-billion dollar industries, there are still a number of scientific questions and technological issues that are unanswered. One key challenge is related to the polar nature of the III-nitride wurtzite crystal. Until a decade ago all research activities had almost exclusively concentrated on (0001)-oriented polar GaN layers and heterostructures. Although the device characteristics seem excellent, the strong polarization fields at GaN heterointerfaces can lead to a significant deterioration of the device performance. Triggered by the first demonstration non-polar GaN quantum wells grown on LiAlO2 by Waltereit and colleagues in 2000, impressive advances in the area of non-polar and semipolar nitride semiconductors and devices have been achieved. Today, a large variety of heterostructures free of polarization fields and exhibiting exceptional electronic and optical properties have been demonstrated, and the fundamental understanding of polar, semipolar and non-polar nitrides has made significant leaps forward. The contributions in this Semiconductor Science and Technology special issue on non-polar and semipolar nitride semiconductors provide an impressive and up-to-date cross-section of all areas of research and device physics in this field. The articles cover a wide range of

  6. Hydrogel iontophoresis for gentamicin administration to the rabbit eye

    Science.gov (United States)

    Eljarrat-Binstock, Esther; Raiskup, Frederik; Frucht-Pery, Joseph; Domb, Abraham J.

    2005-04-01

    Iontophoresis (IONT) is a non-invasive technique in which a low electric current is used to enhance the penetration of charged molecules into tissue. This technique has been used in various fields of medicine, mostly in transdermal drug delivery. This study was aimed to evaluate the efficacy and the distribution profile of gentamicin using corneal IONT on infected and healthy rabbit eyes. Corneal iontophoresis of gentamicin sulfate was studied using drug-loaded disposable hydrogel probes mounted on a portable iontophoretic device, applying a low current for 60 seconds. This study confirmed that a triple iontophoretic treatment of gentamicin for only 60 seconds (0.5mA) significantly reduces the count of pseudomonas in the infected cornea to a non-infectious level. Peak gentamicin concentrations at the healthy corneas (363.1 +/- 127.3 μg/g) and at the aqueous humor (29.4 +/- 17.4 μg/ml) were reached immediately and two hours after a single iontophoretic treatment, respectively. The concentration versus time profile of gentamicin following iontophoresis revealed a gentamicin half life of 2.07 h in the anterior chamber, and a clearance of 1.73 μl/min from the anterior chamber to the posterior segments of the eye. This study indicates that a short iontophoretic treatment using gentamicin-loaded hydrogels has a potential clinical value in treating corneal infections, by increasing drug penetration to the eye and maintaining therapeutic levels for more than eight hours.

  7. Effect of Taurine on the antimicrobial efficiency of Gentamicin

    Directory of Open Access Journals (Sweden)

    Islambulchilar Mina

    2011-12-01

    Full Text Available Context: Gentamicin is mainly used in severe infections caused by gram-negatives. However toxicity including nephrotoxicity and ototoxicity is one of the most important complications of its treatment. The production of free radicals seems to be involved in gentamicin toxicity mechanism. Taurine, a major intracellular free β-amino acid, is known to be an endogenous antioxidant. So potentially the co-therapy of taurine and gentamicin would reduce the adverse effects of the antibiotic. Objectives: In this study, we wished to know the effect of taurine on the antibiotic capacity of gentamicin. methods: strains of P. aeruginosa, E. coli, S. aureus and S. epidermidis were used as test organisms. Minimum inhibitory concentrations of gentamicin in the presence and absence of taurine at quantities from 40 to 2 mg/L were determined using macro-dilution method. Results: MICs were determined in the various concentrations of taurine for bacterial indicators. The MIC values of gentamicin for P. aeruginosa, S. aureus and E. coli remained unchanged in the values of 2.5, 5 and 20 μg/ml respectively in the absence and presences of different concentrations of taurine. The bactericidal activity of gentamicin against S. epidermidis was increased by addition of taurine in the concentrations higher than 6 mg/L. Conclusion: According to our study the antibacterial activity of gentamicin against the indicator microorganisms were not interfere with taurine at selected concentrations. Further in vivo studies are needed to establish if a combination of gentamicin and taurine would have the same effect.

  8. Effects of Kangshen Oral Liquid on Gentamicin-induced Acute ...

    African Journals Online (AJOL)

    Purpose: To investigate the effects of Kangshen oral liquid (KSOL) on gentamicin sulfate (GS)-induced acute kidney injury ..... Upon GS administration, several physiological markers are .... Kara A, Bozkurt A. The protective effect of taurine.

  9. Instrumental characterization of the smectite clay–gentamicin hybrids

    Indian Academy of Sciences (India)

    Alicja Rapacz-Kmita; Ewa Stodolak-Zych; Magdalena Ziabka; Agnieszka Rozycka; Magdalena Dudek

    2015-08-01

    This paper focusses on the intercalation of clay mineral with gentamicin (an aminoglycoside antibiotic). The smectite clay–gentamicin hybrids were prepared by a solution intercalation at 60°C and the process was carried out on unmodified smectite clay and on smectite after Na+ ionic activation. The resulting structural/microstructural properties and the potential for introducing gentamicin between smectite clay layers were investigated by means of X-ray diffraction, Fourier transform infrared spectroscopic techniques and transmission electron microscopy and scanning electron microscopy with energy-dispersive spectroscopy X-ray analysis. The results confirm the successful intercalation of gentamicin into the interlayer space of smectite clay, demonstrating that the material thus obtained could potentially be used as a drug carrier.

  10. Once versus twice daily gentamicin dosing for infective endocarditis

    DEFF Research Database (Denmark)

    Buchholtz, Kristine; Larsen, Carsten Toftager; Schaadt, Bente

    2011-01-01

    to half-life, mean CRP and leukocytes. Results: Baseline GFR was similar in the two groups. Both groups displayed a significant fall in GFR from admission to discharge. The mean decrease in GFR was as follows: with once daily gentamicin, 17.0% (95% confidence interval 7.5– 26.5), and with twice daily......Objectives: The aim of this randomized study was to investigate the effects of once versus twice daily gentamicin dosing on renal function and measures of infectious disease in a population with infective endocarditis (IE). Methods: Seventy-one IE patients needing gentamicin treatment according...... to guidelines were randomized to either once (n = 37) or twice daily (n = 34) doses of gentamicin. Kidney function (glomerular filtration rate, GFR) was measured with an isotope method ( 51 Cr-EDTA) at the beginning of treatment and at discharge. Treatment efficacy was assessed by C-reactive protein (CRP) time...

  11. Acoustic trauma increases cochlear and hair cell uptake of gentamicin.

    Directory of Open Access Journals (Sweden)

    Hongzhe Li

    Full Text Available BACKGROUND: Exposure to intense sound or high doses of aminoglycoside antibiotics can increase hearing thresholds, induce cochlear dysfunction, disrupt hair cell morphology and promote hair cell death, leading to permanent hearing loss. When the two insults are combined, synergistic ototoxicity occurs, exacerbating cochlear vulnerability to sound exposure. The underlying mechanism of this synergism remains unknown. In this study, we tested the hypothesis that sound exposure enhances the intra-cochlear trafficking of aminoglycosides, such as gentamicin, leading to increased hair cell uptake of aminoglycosides and subsequent ototoxicity. METHODS: Juvenile C57Bl/6 mice were exposed to moderate or intense sound levels, while fluorescently-conjugated or native gentamicin was administered concurrently or following sound exposure. Drug uptake was then examined in cochlear tissues by confocal microscopy. RESULTS: Prolonged sound exposure that induced temporary threshold shifts increased gentamicin uptake by cochlear hair cells, and increased gentamicin permeation across the strial blood-labyrinth barrier. Enhanced intra-cochlear trafficking and hair cell uptake of gentamicin also occurred when prolonged sound, and subsequent aminoglycoside exposure were temporally separated, confirming previous observations. Acute, concurrent sound exposure did not increase cochlear uptake of aminoglycosides. CONCLUSIONS: Prolonged, moderate sound exposures enhanced intra-cochlear aminoglycoside trafficking into the stria vascularis and hair cells. Changes in strial and/or hair cell physiology and integrity due to acoustic overstimulation could increase hair cell uptake of gentamicin, and may represent one mechanism of synergistic ototoxicity.

  12. Could edaravone prevent gentamicin ototoxicity? An experimental study.

    Science.gov (United States)

    Turan, M; Ciğer, E; Arslanoğlu, S; Börekci, H; Önal, K

    2017-02-01

    Clinical application of gentamicin may cause nephrotoxicity and ototoxicity. Our study is the first study to investigate the protective effects of edaravone against the gentamicin-induced ototoxicity. We investigated the protective effect of intraperitoneal (i.p.) edaravone application against gentamicin-induced ototoxicity in guinea pigs. Fourteen guinea pigs were divided into two equal groups consisting of a control group and a study group. One-hundred sixty milligrams per kilogram subcutaneous gentamicin and 0.3 mL i.p. saline were applied simultaneously once daily to seven guinea pigs in the control group (group 1). One-hundred sixty milligrams per kilogram gentamicin was applied subcutaneously and 3 mg/kg edaravone was applied intraperitoneally once daily for 7 days simultaneously to seven guinea pigs in the study group (group 2). Following the drug application, auditory brainstem response measurements were performed for the left ear on the 3rd and 7th days. Hearing threshold values of the group 1 and group 2 measured in the 3rd day of the study were detected as 57.14 ± 4.88 and 82.86 ± 7.56, respectively. This difference was statistically significant ( p ototoxic effects of gentamicin and the severity of the hearing loss.

  13. Salicylic Acid Attenuates Gentamicin-Induced Nephrotoxicity in Rats

    Directory of Open Access Journals (Sweden)

    Pavle Randjelovic

    2012-01-01

    Full Text Available Gentamicin (GM is a widely used antibiotic against serious and life-threatening infections, but its usefulness is limited by the development of nephrotoxicity. The present study was designed to determine the protective effect of salicylic acid (SA in gentamicin-induced nephrotoxicity in rats. Quantitative evaluation of gentamicin-induced structural alterations and degree of functional alterations in the kidneys were performed by histopathological and biochemical analyses in order to determine potential beneficial effects of SA coadministration with gentamicin. Gentamicin was observed to cause a severe nephrotoxicity which was evidenced by an elevation of serum urea and creatinine levels. The significant increases in malondialdehyde (MDA levels and protein carbonyl groups indicated that GM-induced tissue injury was mediated through oxidative reactions. On the other hand, simultaneous SA administration protected kidney tissue against the oxidative damage and the nephrotoxic effect caused by GM treatment. Exposure to GM caused necrosis of tubular epithelial cells. Necrosis of tubules was found to be prevented by SA pretreatment. The results from our study indicate that SA supplement attenuates oxidative-stress associated renal injury by reducing oxygen free radicals and lipid peroxidation in gentamicin-treated rats.

  14. Salicylic acid attenuates gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    Randjelovic, Pavle; Veljkovic, Slavimir; Stojiljkovic, Nenad; Jankovic-Velickovic, Ljubinka; Sokolovic, Dusan; Stoiljkovic, Milan; Ilic, Ivan

    2012-01-01

    Gentamicin (GM) is a widely used antibiotic against serious and life-threatening infections, but its usefulness is limited by the development of nephrotoxicity. The present study was designed to determine the protective effect of salicylic acid (SA) in gentamicin-induced nephrotoxicity in rats. Quantitative evaluation of gentamicin-induced structural alterations and degree of functional alterations in the kidneys were performed by histopathological and biochemical analyses in order to determine potential beneficial effects of SA coadministration with gentamicin. Gentamicin was observed to cause a severe nephrotoxicity which was evidenced by an elevation of serum urea and creatinine levels. The significant increases in malondialdehyde (MDA) levels and protein carbonyl groups indicated that GM-induced tissue injury was mediated through oxidative reactions. On the other hand, simultaneous SA administration protected kidney tissue against the oxidative damage and the nephrotoxic effect caused by GM treatment. Exposure to GM caused necrosis of tubular epithelial cells. Necrosis of tubules was found to be prevented by SA pretreatment. The results from our study indicate that SA supplement attenuates oxidative-stress associated renal injury by reducing oxygen free radicals and lipid peroxidation in gentamicin-treated rats.

  15. Intermittent exposure to xenon protects against gentamicin-induced nephrotoxicity.

    Directory of Open Access Journals (Sweden)

    Ping Jia

    Full Text Available Aminoglycoside antibiotics, especially gentamicin, are widely used to treat Gram-negative infections due to their efficacy and low cost. Nevertheless the use of gentamicin is limited by its major side effect, nephrotoxicity. Xenon (Xe provided substantial organoprotective effects in acute injury of the brain and the heart and protected against renal ischemic-reperfusion injury. In this study, we investigated whether xenon could protect against gentamicin-induced nephrotoxicity. Male Wistar rats were intermittently exposed to either 70% xenon or 70% nitrogen (N2 balanced with 30% oxygen before and during gentamicin administration at a dose of 100 mg/kg for 7 days to model gentamicin-induced kidney injury. We observed that intermittent exposure to Xe provided morphological and functional renoprotection, which was characterized by attenuation of renal tubular damage, apoptosis, and oxidative stress, but not a reduction in inflammation. We also found that Xe pretreatment upregulated hypoxia-inducible factor 2α (HIF-2α and its downstream effector vascular endothelial growth factor, but not HIF-1α. With regard to the three HIF prolyl hydroxylases, Xe pretreatment upregulated prolyl hydroxylase domain-containing protein-2 (PHD2, suppressed PHD1, and had no influence on PHD3 in the rat kidneys. Pretreatment with Xe also increased the expression of miR-21, a microRNA known to have anti-apoptotic effects. These results support Xe renoprotection against gentamicin-induced nephrotoxicity.

  16. Clinicopathological Studies on Gentamicin Toxicity in White Leghorn Commercial Layers

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    Najam Ul Islam, M. Zargham Khan1, M. Kashif Saleemi*1, Ahrar Khan1, Sheraz Ahmed Bhatti1, Muhammad Yousaf2 and Zahoor-ul-Hassan3

    2011-10-01

    Full Text Available Gentamicin is an effective and economical drug used to control infectious diseases in poultry but is highly toxic and had slow clearance from the body. This study aimed to report three cases of gentamicin toxicity in three White Leghorn (WLH layer flocks in different poultry producing areas of Pakistan. In first case, gentamicin was injected in a 9000 WLH layer flock @ 10 mg/kg body weight (BW for seven times during 9-15 weeks for age. In second case, gentamicin was injected in a flock of 7500 WLH layers @ 25 mg/kg BW for four times during 17-18 weeks of age. In third case, gentamicin was injected in flock of 16000 WLH layers @ 22.22 mg/kg BW three times in 20-21 weeks of age. Flock wise mortality was 8.69, 82.63 and 71.86%, respectively. Birds were dehydrated, emaciated and had prominent keel bone. Clinical signs included dehydration, decreased body weight leading to emaciation, decreased feed intake, increased water intake and watery diarrhea. Necropsy revealed prominent keal bone, shrunken muscles swollen kidneys bulging out from bony sockets. Petechial and echymotic hemorrhages were present on heart and skeletal muscles. Liver was enlarged with hemorrhagic streaks on its surface. Microscopically, hemorrhages and acute tubular necrosis was recorded in kidneys. Liver had hemorrhages, cellular infiltration and vacuolar (fatty degeneration of hepatocytes. From the results, it could be concluded that overdosing and repeated administration of gentamicin was highly toxic to birds.

  17. Some pharmacokinetic and pharmacodynamic interactions between digoxin and gentamicin.

    Science.gov (United States)

    Staneva-Stoytcheva, D; Kristeva, E; Prodanova, K

    1992-01-01

    Some pharmacokinetic and pharmacodynamic interactions between digoxin and gentamicin were studied in experiments on rabbits, guinea-pigs and cats. An increase of digoxin serum levels and changes in some basic pharmacokinetic parameters of digoxin (t1/2 alpha t1/2 beta, AUC, C1) were found in gentamicin-pretreated rabbits, the changes being dependent on the dose and schedule of administration. The most pronounced changes were those in digoxin kinetics during simultaneous 5-day treatment with digoxin (0.035 mg/kg i.v.) and nontoxic (10 and 2 mg/kg) doses of gentamicin. The toxicity of digoxin in guinea-pigs, assessed by administration of lethal doses of digoxin, was increased only after the highest dose of gentamicin (100 mg/kg), while after nontoxic or close to therapeutic doses (10 and 2 mg/kg) of gentamicin, the digoxin toxicity was either unchanged or even decreased. Digoxin decreased the nerve-muscle blocking effect of gentamicin on cat ischiadicus-gastrocnemius preparation. The possible mechanisms involved are discussed.

  18. Patients’ safety: is there a systemic release of gentamicin by gentamicin-coated tibia nails in clinical use?

    Directory of Open Access Journals (Sweden)

    Moghaddam A

    2016-09-01

    Full Text Available Arash Moghaddam,1 Viola Graeser,1 Fabian Westhauser,1 Ulrike Dapunt,1 Till Kamradt,1 Stefan M Woerner,2 Gerhard Schmidmaier1 1HTRG – Heidelberg Traume Research Group Center for Orthopedics, Trauma and Spinal Cord Injury, University Hospital Heidelberg, Heidelberg, Germany; 2Department of Internal Medicine and Clinical Chemistry, University Hospital Heidelberg, Heidelberg, Germany Introduction: Osteitis is one of the most serious complications in orthopedic surgery. Expert Tibia Nail (ETN PROtect™ coated with a biodegradable layer of gentamicin-laden polymer was developed for prophylaxis of osteomyelitis. In systemic administration, gentamicin has only a small therapeutic index and serious side effects; it is potentially nephrotoxic as well as ototoxic. It is not yet known if relevant gentamicin concentrations are released into the systemic circulation after implantation of gentamicin-coated nails. In order to evaluate the patients’ risks profiles and increase patient safety, we measured gentamicin levels in pre- and postoperative serum samples of patients undergoing implantation of ETN PROtect.Methods: Twenty-five patients who received ETN PROtect between March 2012 and August 2014 were included in this study. Collection of blood samples occurred before the operation, at weeks 1–4, 3 and 6 months, and up to 1 year after the implantation. Measurement of gentamicin levels in serum samples was performed at the central laboratory of Heidelberg University Hospital. Additionally, laboratory parameters, C-reactive protein, leukocyte number, urea and creatinine concentrations were analyzed in routine controls before and after operating and assessed for systemic side effects.Results: Over the course of this prospective observational study, we were able to determine that gentamicin-coated nails do not release gentamicin into the systemic circulation above the lowest detectable level of 0.2 mg/dL. There were slight increases in the mean

  19. Fagonia olivieri prevented hepatorenal injuries induced with gentamicin in rat.

    Science.gov (United States)

    Rashid, Umbreen; Khan, Muhammad Rashid

    2017-04-01

    Gentamicin is used clinically against Gram negative bacteria because of its efficacy. However, it causes renal injuries and failure at clinical dosages on account of induced oxidative stress. Fagonia olivieri is used in kidneys, liver, alimentary canal and cardiovascular disorders in local system of medicine in Pakistan. This study evaluates the protective abilities of methanol extract of F. olivieri (FOM) against the liver and renal injuries induced with gentamicin in rat. Sprague-Dawley male rats were treated with gentamicin (80mg/kg) alone or with silymarin (50mg/kg) as standard antioxidant drug. The other groups of rats were treated with gentamicin along with FOM (200mg/kg, 400mg/kg) or FOM (400mg/kg) alone. Effect of FOM was investigated on body weight, urine and serum biochemical markers, enzymatic antioxidants of renal and liver along with histopathological alterations. FOM was investigated by GC-MS for the presence of bioactive constituents. Treatment of FOM to rats ameliorated the gentamicin induced toxicity and increased the percent increase in body weight while decreased the absolute and relative weight of hepatic and kidneys. Gentamicin increased the level of specific gravity, count of RBCs and WBCs, and urobilinogen in urine; and AST, ALT, ALP, LDH, total bilirubin, total cholesterol, triglycerides and LDL in serum. Level of lipid peroxides in terms of thiobarbituric acid reactive substances (TBARS) and DNA damages increased while the GSH contents and activity level of CAT, SOD, GSH-Px and GR decreased with gentamicin in liver and kidney samples. Co-treatment of FOM, dose dependently, alleviated the injuries induced with gentamicin. Histopathological studies of liver and kidneys supported the protective abilities of FOM. GC-MS analysis indicated the presence of various compounds including hexadecanoic acid, 2-methoxy-4-vinylphenol, benzoic acid and thalicpureine in the FOM. Results of the present investigation suggested the protective potential of FOM

  20. Effect of platelet activating factor antagonist treatment on gentamicin nephrotoxicity

    Directory of Open Access Journals (Sweden)

    A. Rodriguez-Barbero

    1992-01-01

    Full Text Available To assess whether PAF could be involved in the gentamicin-induced nephrotoxicity, we have studied the effect of PAF antagonist BN-52021 on renal function in rats after gentamicin (GENTA treatment. Experiments were completed in 21 Wistar rats divided into three groups: group GENTA was injected with gentamicin 100 mg kg−1 body wt/day s.c. for 6 days. Group GENTA + BN received gentamicin and BN-52021 i.p. 5 mg kg−1 body wt/day. A third group served as control. Rats were placed in meta-bolic cages and plasma creatinine and creatinine clearance were measured daily. GENTA group showed a progressive increase in plasma creatinine, a drop in creatinine clearance and an increase in urinary excretion of N-acetyl-β-D-glucosaminidase and alkaline phosphatase. GENTA + BN group showed a lesser change in plasma creatinine and a creatinine clearance, but no difference with GENTA group in urinary excretion of NAG and AP were observed. Histological examination revealed a massive cortical tubular necrosis in rats treated with gentamicin, whereas in BN-52021 injected animals tubular damage was markedly attenuated. The present results suggest a role for PAF in the gentamicininduced nephro-toxicity.

  1. Doripenem, Gentamicin, and Colistin, Alone and in Combinations, against Gentamicin-Susceptible, KPC-Producing Klebsiella pneumoniae Strains with Various ompK36 Genotypes

    Science.gov (United States)

    Clancy, Cornelius J.; Hao, Binghua; Shields, Ryan K.; Chen, Liang; Perlin, David S.; Kreiswirth, Barry N.

    2014-01-01

    Gentamicin doses of 2 and 10 μg/ml were bactericidal against 64% and 100%, respectively, of gentamicin-susceptible KPC-2-producing Klebsiella pneumoniae strains. Treatment with the combination of doripenem (8 μg/ml) plus colistin (2 μg/ml) was inferior to treatment with gentamicin (2 μg/ml), doripenem-gentamicin, gentamicin-colistin, and doripenem-gentamicin-colistin against strains with glycine and aspartic acid insertions in OpmK36 porin at amino acid (aa) positions 134 and 135 (n = 9). Doripenem-colistin was comparable to other 2- or 3-drug regimens and superior to single drugs against wild-type/minor ompK36 mutants (n = 5). An algorithm incorporating ompK36 genotypes and susceptibility to gentamicin and doripenem may predict antimicrobial activity against KPC-producing K. pneumoniae. PMID:24566172

  2. Partridge embryo pathology in relation to gentamicin-induced lesions

    Directory of Open Access Journals (Sweden)

    Hadi Tavakkoli

    2016-10-01

    Full Text Available Objective: To determine the macroscopic and microscopic lesions of various dosages of gentamicin in the partridge embryo. Methods: Fertile chukar partridge eggs were allocated into four groups. Group 1: salineinjected group whose individuals were administered by sterile physiological saline solution of 0.2 mL/egg inserted into yolk sac. Groups 2, 3 and 4 whose individuals were similarly administered by gentamicin sulfate at a dosage of 80 mg/kg egg-weight once, twice and three times, respectively. Results: Results showed that the embryos were congested and stunted in the gentamicininjected groups. Defects in feet, wings and feather development were accompanied by microscopic lesions in brain, meninges, heart, lungs, liver and kidneys. Histopathological lesions were noticed as edema, undeveloped tissues, necrosis and degeneration in the affected organs. Conclusions: Based on acquired results, it is concluded that gentamicin at above-described dosages causes toxicopathological effects to the partridge embryo in a dose dependent manner.

  3. Antibiotic disposition in experimental pneumonic pasteurellosis: gentamicin and tylosin.

    Science.gov (United States)

    Burrows, G E; Barto, P B; Martin, B

    1986-01-01

    The effects of severe respiratory disease on the disposition of antibiotics were evaluated using two drugs chosen because of their widely differing solubility characteristics. The experiments were carried out in series, using five calves for each drug. The drugs were given to seven week old calves before and after induction of pneumonia by bilateral intrapulmonary administration of 3 mL of 5 X 10(7) colony forming units of Pasteurella haemolytica. Following inoculation, the calves developed clinical signs of pneumonia and were given gentamicin (5 mg/kg) or tylosin (10 mg/kg) 48, 60 and 72 hours after Pasteurella administration. There was a statistically significant decrease in distribution rate but not elimination rate of gentamicin. For tylosin, there was a significant increase in elimination rate. These results indicate the kinetics of tylosin but not gentamicin are sufficiently altered as to support a need for increased frequency of administration with severe respiratory disease in calves. Images Fig. 2. PMID:3756673

  4. Developmental pharmacokinetics of gentamicin in preterm and term neonates

    DEFF Research Database (Denmark)

    Nielsen, Elisabet I; Sandström, Marie; Honoré, Per Hartvig;

    2009-01-01

    for concentration monitoring. This study was performed to characterize the population pharmacokinetics of gentamicin in preterm and term neonates and to identify and quantify relationships between patient characteristics and IIV. A secondary aim was to evaluate cystatin C as a marker for gentamicin clearance...... was included as the primary covariate according to an allometric power model. Other evaluated covariates were age (postmenstrual age, gestational age [GA], postnatal age [PNA]), markers for renal function (serum creatinine, serum cystatin C) and concomitant medication with cefuroxime, vancomycin or indometacin...... as having a significant influence on the central volume of distribution, with a preterm neonate having a larger central volume of distribution per kilogram of bodyweight than a term neonate. Cystatin C and creatinine were not correlated with gentamicin clearance in this study population. The external...

  5. Cochlear and Vestibular Effects of Combined Intratympanic Gentamicin and Dexamethasone.

    Science.gov (United States)

    Güneri, Enis Alpin; Olgun, Yüksel; Aslıer, Mustafa; Nuti, Daniele; Kırkım, Günay; Mungan, Serpil; Kolatan, Efsun; Aktaş, Safiye; Trabalzini, Franco; Ellidokuz, Hülya; Yılmaz, Osman; Mandala, Marco

    2017-04-01

    The aim of this study is to evaluate the effects of an intratympanic gentamicin-dexamethasone combination on the inner ear. Twenty-six Wistar albino rats were divided into four groups: Group I (Control), group II (Intratympanic dexamethasone; ITD), group III (Intratympanic gentamicin; ITG), and group IV (Intratympanic gentamicin and dexamethasone; ITGD). On the first day after basal auditory brainstem response (ABR) measurements, the ITG group received 0.03 mL of intratympanic gentamicin (26.7 mg/mL). Intratympanic injection of 0.06 mL of a solution containing 13.35 mg/mL gentamicin and 2 mg/mL dexamethasone was performed in the ITGD group. 0.03 mL of physiological intratympanic serum and dexamethasone (4 mg/mL) was applied in control and ITD groups, respectively. On the 7th day, ABR measurements were repeated and vestibular functions were evaluated. On the 21th day, ABR and vestibular tests were repeated, and the animals were sacrificed for histopathological investigation. The ITG group's hearing thresholds deteriorated in all frequencies. The ITGD group's hearing thresholds were significantly better than the ITG group, except at 8 kHz on the 7th day and in all frequencies at the 21th day measurements. The vestibular function scores of the ITG and ITGD groups were higher than the controls. Apoptotic changes were seen in cochlea, spiral ganglion, and vestibule of the ITG group. Cochlear and vestibular structures were well preserved in the ITGD group, similar to the controls. The ITGD combination led to a significant hearing preservation. Although in subjective vestibular tests, it seemed that vestibulotoxicity was present in both ITG and ITGD groups the histopathological investigations revealed no signs of vestibulotoxicity in the ITGD group in contrast to the ITG group. Further studies using a combination of different concentrations of gentamicin and dexamethasone are needed.

  6. Non-Polar Natural Products from Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile (Bromeliaceae

    Directory of Open Access Journals (Sweden)

    Ole Johan Juvik

    2017-09-01

    Full Text Available Extensive regional droughts are already a major problem on all inhabited continents and severe regional droughts are expected to become an increasing and extended problem in the future. Consequently, extended use of available drought resistant food plants should be encouraged. Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile are excellent candidates in that respect because they are established drought resistant edible plants from the semi-arid Caatinga region. From a food safety perspective, increased utilization of these plants would necessitate detailed knowledge about their chemical constituents. However, their chemical compositions have previously not been determined. For the first time, the non-polar constituents of B. laciniosa, N. variegata and E. spectabile have been identified. This is the first thorough report on natural products from N. variegata, E. spectabile, and B. laciniosa. Altogether, 20 non-polar natural products were characterized. The identifications were based on hyphenated gas chromatography-high resolution mass spectrometry (GC-HRMS and supported by 1D and 2D Nuclear Magnetic Resonance (NMR plant metabolomics.

  7. Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

    DEFF Research Database (Denmark)

    Lawætz, Peter

    1969-01-01

    The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering. Fo...

  8. The role of solvent cohesion in nonpolar solvation

    NARCIS (Netherlands)

    Otto, Sijbren

    2013-01-01

    Understanding hydrophobic interactions requires a molecular-level picture of how water molecules adjust to the introduction of a nonpolar solute. New insights into the latter process are derived from the observation that the Gibbs energies of solvation of the noble gases and linear alkanes by a wide

  9. Protective effect of quercetin in gentamicin-induced oxidative stress in vitro and in vivo in blood cells. Effect on gentamicin antimicrobial activity.

    Science.gov (United States)

    Bustos, Pamela Soledad; Deza-Ponzio, Romina; Páez, Paulina Laura; Albesa, Ines; Cabrera, José Luis; Virgolini, Miriam Beatriz; Ortega, María Gabriela

    2016-12-01

    We have evaluated the effect of gentamicin and gentamicin plus quercetin on ROS production, endogenous antioxidant defenses (SOD and CAT) and lipid peroxidation in vitro on human leukocytes and in vivo on whole rat blood. Gentamicin generated ROS production in human leukocytes, produced a dual effect on both enzymes dosage-dependent and generated an increase in lipid peroxidation. Quercetin, in leukocytes stimulated by gentamicin, showed more inhibitory capacity in ROS production than the reference inhibitor (vitaminC) in mononuclear cells and a similar protective behavior at this inhibitor in polymorphonuclear cells. Quercetin, in both cellular systems, tend to level SOD and CAT activities, reaching basal values and could prevent lipidic peroxidation induced by gentamicin. The results in Wistar rats confirmed that therapeutic doses of gentamicin can induce oxidative stress in whole blood and that the gentamicin treatment plus quercetin can suppress ROS generation, collaborate with SOD and CAT and diminish lipid peroxidation. Finally, flavonoid and antibiotic association was evaluated on the antimicrobial activity in S. aureus and E. coli, showing that changes were not generated in the antibacterial activity of gentamicin against E. coli strains, while for strains of S. aureus a beneficial effect observes. Therefore, we have demonstrated that gentamicin could induce oxidative stress in human leukocytes and in whole blood of Wistar rats at therapeutic doses and that quercetin may to produce a protective effect on this oxidative stress generated without substantially modifying the antibacterial activity of gentamicin against E. coli strains, and it contributes to this activity against S. aureus strains.

  10. Use of Liposomal Gentamicin for Treatment of 5 Foals with Experimentally Induced Rhodococcus equi Pneumonia.

    Science.gov (United States)

    Cohen, N D; Giguère, S; Burton, A J; Rocha, J N; Berghaus, L J; Brake, C N; Bordin, A I; Coleman, M C

    2016-01-01

    Adverse effects of, and bacterial resistance to, macrolides used to treat Rhodococcus equi infections have prompted search for clinically effective alternative antimicrobials. Liposomal gentamicin (LG) is effective against R. equi in vitro and decreases tissue concentrations of R. equi in experimentally infected mice. Effectiveness of LG treatment of foals with R. equi pneumonia, however, has not been described. Liposomal gentamicin is safe and effective for treating foals with R. equi pneumonia. Ten foals with experimentally induced R. equi pneumonia. Pilot treatment trial. Foals with pneumonia induced by intrabronchial instillation of R. equi were randomly allocated to receive either clarithromycin combined with rifampin (CLR + RIF) PO or LG IV, and followed by daily physical examinations and weekly thoracic ultrasonography and serum creatinine concentration determinations until the resolution of clinical signs. Treatment success was defined as the resolution of clinical signs and ultrasonographically identified pulmonary abscesses. All 10 foals were successfully treated. Two of 5 foals treated with LG developed azotemia within 1 week; LG was discontinued and treatment switched to CLR + RIF for these foals. None of the CLR + RIF treated foals developed azotemia. Liposomal gentamicin IV can be effective for treatment of R. equi pneumonia, but nephrotoxicity indicates that an alternative dosing interval or route (such as nebulization) will be needed before LG is adequately safe for clinical use. Larger comparative trials will be needed to evaluate the relative efficacy of a safer LG dosage regimen. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  11. Concepts for increasing gentamicin release from handmade bone cement beads

    NARCIS (Netherlands)

    Rasyid, Hermawan N; van der Mei, Henny C; Frijlink, Henderik W; Soegijoko, Soegijardjo; Van Horn, Jim R; Busscher, Hendrik; Neut, Daniëlle

    2009-01-01

    BACKGROUND AND PURPOSE: Commercial gentamicin-loaded bone cement beads (Septopal) constitute an effective delivery system for local antibiotic therapy. These beads are not available in all parts of the world, and are too expensive for frequent use in others. Thus, orthopedic surgeons worldwide make

  12. Dose-Dependent Amelioration of Gentamicin-Induced ...

    African Journals Online (AJOL)

    Dose-Dependent Amelioration of Gentamicin-Induced Nephrotoxicity in Adult Swiss Albino ... Purpose: To evaluate the effect of vitamin B-complex on the nephrotoxicity of ... increase in serum urea and creatine while 3ml/kg of the same drug ...

  13. Serum concentrations of gentamicin following oral administration to preterm newborns.

    Science.gov (United States)

    Grylack, L; Boehnert, J; Scanlon, J

    1982-01-01

    Serum gentamicin concentration was measured in 31 newborn babies who received oral gentamicin for prophylaxis of necrotizing enterocolitis in order to determine the presence and degree of gastrointestinal absorption and its relationship to birth weight, gestational age, postnatal age and perinatal asphyxia. A dose of 2.5 mg/kg every 6 h by nasogastric tube was administered during a 3-week course after birth. The mean birth weight was 1,269 +/- 489 g; mean gestational age 29.6 +/- 3.7 weeks. The mean serum gentamicin levels were: 0.06 +/- 0.03 microgram/ml at 30 min after the first dose; 0.29 +/- 0.48 microgram/ml at 4 h; 1.62 +/- 1.43 microgram/ml at 24 h, and 0.33 +/- 0.57 microgram/ml at 7 days. The 24-hour and 7-day samples were taken before the next dose. The mean 24-hour level was significantly (p less than 0.001) higher than the other levels. There was no significant (p less than 0.05) relationship between the 24-hour serum gentamicin level and birth weight, gestational age or umbilical venous pH.

  14. Once daily dose gentamicin in neonates - is our dosing correct?

    Science.gov (United States)

    Serane, Tiroumourougane V; Zengeya, Stanley; Penford, Gemma; Cooke, Jane; Khanna, Gitika; McGregor-Colman, Elle

    2009-07-01

    The aim of this paper is to study the safety and efficacy (measured by therapeutic level) of once daily gentamicin in neonates >or=32 weeks of gestation and or=32 weeks of gestation and 2 mg/L. Only 39 (60%) had peak and trough levels within the therapeutic range. All babies who had audiometric evaluation (62 out of 65) had normal hearing. Out of the 65 babies, 60 had paired serum creatinine levels estimated and none had evidence of renal dysfunction. Among term neonates, only 2 out of 50 had the trough serum concentration of >2 mg/L. In 38 (76%) of the 50 neonates, the trough serum gentamicin concentration was <2.0 mg/L and the peak level was <10 mg/L. Forty-eight babies had audiometric evaluation which was normal. A dose of 4 mg/kg/day produces serum gentamicin levels outside the therapeutic range in two-fifths of neonates between 32 and 36 +/- 6 weeks. A single dose of 4 mg/kg/day of gentamicin is appropriate for term babies and probably excessive for 32-36 weeks' neonates.

  15. Synergistic action of gentamicin and bacteriophage in a continuous culture population of Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Amy E Kirby

    Full Text Available With the increasing frequency of antibiotic resistance and the decreasing frequency of new antibiotics entering the market, interest has returned to developing bacteriophage as a therapeutic agent. Acceptance of phage therapy, however, is limited by the unknown pharmacodynamics of a replicating agent, as well as the potential for the evolution of resistant bacteria. One way to overcome some of these limitations is to incorporate phage and antibiotics into a dual therapy regimen; however, this increases the complexity of the pharmacodynamics. The aim of this study is to develop an experimental system to evaluate the pharmacodynamics of dual phage-drug therapy. A continuous culture system for Staphylococcus aureus is used to simulate the pharmacokinetics of periodic antibiotic dosing alone and in combination with lytic phage. A computer model representation of the system allows further evaluation of the conditions governing the observed pharmacodynamics. The results of this experimental/modeling approach suggest that dual therapy can be more efficacious than single therapies, particularly if there is an overlap in the physiological pathways targeted by the individual agents. In this case, treatment with gentamicin induces a population of cells with a strong aggregation phenotype. These aggregators also have an increased ability to form biofilm, which is a well-known, non-genetic mechanism of drug resistance. However, the aggregators are also more susceptible than the parental strain to the action of the phage. Thus, dual treatment with gentamicin and phage resulted in lower final cell densities than either treatment alone. Unlike in the phage-only treatment, phage-resistant isolates were not detected in the dual treatment.

  16. Alpha-linolenic acid protects against gentamicin induced toxicity

    Directory of Open Access Journals (Sweden)

    Priyadarshini M

    2012-11-01

    Full Text Available Medha Priyadarshini, Mohammad Aatif, Bilqees BanoDepartment of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, IndiaBackground: Recent studies indicate that reactive oxygen species are the major culprits behind the renal damage induced by gentamicin, an aminoglycoside antibiotic used to treat serious and life threatening Gram-negative infections. Experimental evidence suggests a protective role of alpha-linolenic acid supplementation against oxidative stress. The aim of the present study was to investigate the possible beneficial role of alpha-linolenic acid against gentamicin induced renal distress.Methods: Male Wistar rats were divided into three groups of eight rats each, with the first group serving as a control. The other groups were treated intraperitoneally with gentamicin 100 mg/kg body weight per day for 10 days ± alpha-linolenic acid and vitamin E (each given as 250 mg/kg body weight per day. Concentrations of creatinine, urea, cholesterol, inorganic phosphate in serum, malondialdehyde and total sulfhydryl levels, and glutathione-S-transferase, superoxide dismutase, and catalase activity in kidney tissues were determined.Results: Administration of gentamicin to rats induced marked renal failure, characterized by a profound increase in serum creatinine, urea, and cholesterol concentrations, accompanied by significant lowering of renal alkaline phosphatase and acid phosphatase activity, an increase in malondialdehyde, a decline in total sulfhydryl levels, and lowered superoxide dismutase, catalase, and glutathione-S-transferase activity. Cotreatment with alpha-linolenic acid produced amelioration in these biochemical indices of nephrotoxicity in serum as well as in tissue. Further histopathological and human studies are necessary to demonstrate the beneficial effects of alpha-linolenic acid in renal disease.Conclusion: Alpha-linolenic acid may represent a nontoxic and effective intervention strategy in

  17. Antibacterial Efficacy of a New Gentamicin-Coating for Cementless Prostheses Compared to Gentamicin-Loaded Bone Cement

    NARCIS (Netherlands)

    Neut, Danielle; Dijkstra, Rene J. B.; Thompson, Jonathan I.; van der Mei, Henny C.; Busscher, Henk J.

    2011-01-01

    Cementless prostheses are increasingly popular but require alternative prophylactic measures than the use of antibiotic-loaded bone cements. Here, we determine the 24-h growth inhibition of gentamicin-releasing coatings from grit-blasted and porous-coated titanium alloys, and compare their antibacte

  18. Attenuation of Pseudomonas aeruginosa biofilm formation by Vitexin: A combinatorial study with azithromycin and gentamicin

    Science.gov (United States)

    Das, Manash C.; Sandhu, Padmani; Gupta, Priya; Rudrapaul, Prasenjit; de, Utpal C.; Tribedi, Prosun; Akhter, Yusuf; Bhattacharjee, Surajit

    2016-03-01

    Microbial biofilm are communities of surface-adhered cells enclosed in a matrix of extracellular polymeric substances. Extensive use of antibiotics to treat biofilm associated infections has led to the emergence of multiple drug resistant strains. Pseudomonas aeruginosa is recognised as a model biofilm forming pathogenic bacterium. Vitexin, a polyphenolic group of phytochemical with antimicrobial property, has been studied for its antibiofilm potential against Pseudomonas aeruginosa in combination with azithromycin and gentamicin. Vitexin shows minimum inhibitory concentration (MIC) at 260 μg/ml. It’s antibiofilm activity was evaluated by safranin staining, protein extraction, microscopy methods, quantification of EPS and in vivo models using several sub-MIC doses. Various quorum sensing (QS) mediated phenomenon such as swarming motility, azocasein degrading protease activity, pyoverdin and pyocyanin production, LasA and LasB activity of the bacteria were also evaluated. Results showed marked attenuation in biofilm formation and QS mediated phenotype of Pseudomonas aeruginosa in presence of 110 μg/ml vitexin in combination with azithromycin and gentamicin separately. Molecular docking of vitexin with QS associated LuxR, LasA, LasI and motility related proteins showed high and reasonable binding affinity respectively. The study explores the antibiofilm potential of vitexin against P. aeruginosa which can be used as a new antibiofilm agent against microbial biofilm associated pathogenesis.

  19. Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

    KAUST Repository

    Leonard, J. T.

    2015-07-06

    © 2015 AIP Publishing LLC. We report on our recent progress in improving the performance of nonpolar III-nitride vertical-cavity surface-emitting lasers (VCSELs) by using an Al ion implanted aperture and employing a multi-layer electron-beam evaporated ITO intracavity contact. The use of an ion implanted aperture improves the lateral confinement over SiNx apertures by enabling a planar ITO design, while the multi-layer ITO contact minimizes scattering losses due to its epitaxially smooth morphology. The reported VCSEL has 10 QWs, with a 3nm quantum well width, 1nm barriers, a 5nm electron-blocking layer, and a 6.95- λ total cavity thickness. These advances yield a single longitudinal mode 406nm nonpolar VCSEL with a low threshold current density (∼16kA/cm2), a peak output power of ∼12μW, and a 100% polarization ratio. The lasing in the current aperture is observed to be spatially non-uniform, which is likely a result of filamentation caused by non-uniform current spreading, lateral optical confinement, contact resistance, and absorption loss.

  20. Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

    Science.gov (United States)

    Leonard, J. T.; Cohen, D. A.; Yonkee, B. P.; Farrell, R. M.; Margalith, T.; Lee, S.; DenBaars, S. P.; Speck, J. S.; Nakamura, S.

    2015-07-01

    We report on our recent progress in improving the performance of nonpolar III-nitride vertical-cavity surface-emitting lasers (VCSELs) by using an Al ion implanted aperture and employing a multi-layer electron-beam evaporated ITO intracavity contact. The use of an ion implanted aperture improves the lateral confinement over SiNx apertures by enabling a planar ITO design, while the multi-layer ITO contact minimizes scattering losses due to its epitaxially smooth morphology. The reported VCSEL has 10 QWs, with a 3 nm quantum well width, 1 nm barriers, a 5 nm electron-blocking layer, and a 6.95- λ total cavity thickness. These advances yield a single longitudinal mode 406 nm nonpolar VCSEL with a low threshold current density (˜16 kA/cm2), a peak output power of ˜12 μW, and a 100% polarization ratio. The lasing in the current aperture is observed to be spatially non-uniform, which is likely a result of filamentation caused by non-uniform current spreading, lateral optical confinement, contact resistance, and absorption loss.

  1. Mentha piperita in nephrotoxicity - a possible intervention to ameliorate renal derangements associated with gentamicin

    Directory of Open Access Journals (Sweden)

    Naveed Ullah

    2014-01-01

    Full Text Available Objective: Free radical generation has a strong role in the pathogenesis of renal damage associated with the use of gentamicin. Therefore, the present study was carried out to evaluate the renoprotective effect of Mentha piperita against gentamicin induced nephrotoxicity. Materials and Methods: A total of 24 male rabbits were divided into 4 groups receiving normal saline, gentamicin, M. piperita extract and co-therapy of extract and gentamicin respectively. Gentamicin was provided as 80 mg/kg/day intramuscularly and extract was given 200 mg/kg/day orally for a period of 21 days. Serum and urinary biochemical parameters and histological changes were studied for each group. The impact of the extract on the antibacterial action of gentamicin was also evaluated. Results: Animals treated with gentamicin showed derangements in serum and urinary biochemical parameters. These alterations were reversed by treatment with M. piperita extract. The histological changes showed in gentamicin group were also reverted by treatment with the extract. Further the plant did not influence the efficacy of gentamicin with respect to its antimicrobial properties. Conclusion: Co-therapy of M. piperita with gentamicin successfully attenuated biochemical kidney functioning derangements and morphological changes associated with gentamicin.

  2. Fluctuation capture in non-polar gases and liquids

    CERN Document Server

    Cocks, D G

    2016-01-01

    We present a new model to identify natural fluctuations in fluids, allowing us to describe localization phenomena in the transport of electrons, positrons and positronium through non-polar fluids. The theory contains no free parameters and allows for the calculation of capture cross sections $\\sigma_{cap}(\\epsilon)$ of light-particles in any non-polar fluid, required for non-equilibrium transport simulations. We postulate that localization occurs through large shallow traps before stable bound states are formed. Our results allow us to explain most of the experimental observations of changes in mobility and annihilation rates in the noble gases and liquids as well as make predictions for future experiments. Quantities which are currently inaccessible to experiment, such as positron mobilities, can be obtained from our theory. Unlike other theoretical approaches to localization, the outputs of our theory can be applied in non-equilibrium transport simulations and an extension to the determination of waiting ti...

  3. Nanoencapsulation of Fullerenes in Organic Structures with Nonpolar Cavities

    Science.gov (United States)

    Murthy, C. N.

    2005-01-01

    The formation of supramolecular structures, assemblies, and arrays held together by weak intermolecular interactions and non-covalent binding mimicking natural processes has been used in applications being anticipated in nanotechnology, biotechnology and the emerging field of nanomedicine. Encapsulation of C60 fullerene by cyclic molecules like cyclodextrins and calixarenes has potential for a number of applications. Similarly, biomolecules like lysozyme also have been shown to encapsulate C60 fullerene. This poster article reports the recent trends and the results obtained in the nanoencapsulation of fullerenes by biomolecules containing nonpolar cavities. Lysozyme was chosen as the model biomolecule and it was observed that there is no covalent bond formed between the bimolecule and the C60 fullerene. This was confirmed from fluorescence energy transfer studies. UV Vis studies further supported this observation that it is possible to selectively remove the C60 fullerene from the nonpolar cavity. This behavior has potential in biomedical applications

  4. Nanoencapsulation of Fullerenes in Organic Structures with Nonpolar Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, C. N. [M.S. University of Baroda, Applied Chemistry Department, Faculty of Technology and Engineering (India)

    2005-01-15

    The formation of supramolecular structures, assemblies, and arrays held together by weak intermolecular interactions and non-covalent binding mimicking natural processes has been used in applications being anticipated in nanotechnology, biotechnology and the emerging field of nanomedicine. Encapsulation of C{sub 60} fullerene by cyclic molecules like cyclodextrins and calixarenes has potential for a number of applications. Similarly, biomolecules like lysozyme also have been shown to encapsulate C{sub 60} fullerene. This poster article reports the recent trends and the results obtained in the nanoencapsulation of fullerenes by biomolecules containing nonpolar cavities. Lysozyme was chosen as the model biomolecule and it was observed that there is no covalent bond formed between the bimolecule and the C{sub 60} fullerene. This was confirmed from fluorescence energy transfer studies. UV-Vis studies further supported this observation that it is possible to selectively remove the C{sub 60} fullerene from the nonpolar cavity. This behavior has potential in biomedical applications

  5. Thermodiffusion in binary and ternary nonpolar hydrocarbon + alcohol mixtures

    Science.gov (United States)

    Eslamian, Morteza; Saghir, M. Ziad

    2012-12-01

    Thermodiffusion in complex mixtures, such as associating, molten metal, and polymer mixtures is difficult to model usually owing to the occurrence of a sign change in the thermodiffusion coefficient when the mixture concentration and temperature change. A mixture comprised of a nonpolar hydrocarbon and an alcohol is a complex and highly non-ideal mixture. In this paper an existing binary non-equilibrium thermodynamics model (Eslamian and Saghir, Physical Review E 80, 061201, 2009) developed for aqueous mixtures of alcohols is examined against the experimental data of binary nonpolar hydrocarbon and alcohol mixtures. For ternary mixtures, non-equilibrium thermodynamic expressions developed by the authors for aqueous mixtures of alcohols (Eslamian and Saghir, Canadian Journal of Chemical Engineering, DOI 10.1002/cjce.20581) is used to predict thermodiffusion coefficients of ternary nonpolar hydrocarbon and alcohol mixtures. The rationale behind the sign change is elucidated and attributed to an anomalous change in the molecular structure and therefore viscosity of such mixtures. Model predictions of thermodiffusion coefficients of binary mixtures predict a sign change consistent with the experimental data although the model is still too primitive to capture all structural complexities. For instance, in the methanol-benzene mixture where the model predictions are poorest, the viscosity data show that when concentration varies, the mixture's molecular structure experiences a severe change twice, the first major change leading to a maximum in the thermodiffusion coefficient, whereas the second change causes a sign change.

  6. Protective potential of Tamarindus indica against gentamicin-induced nephrotoxicity.

    Science.gov (United States)

    Ullah, Naveed; Azam Khan, Mir; Khan, Taous; Ahmad, Waqar

    2014-01-13

    Abstract Context: Gentamicin is an antibiotic that is effective against Gram-negative microorganisms. However, its clinical applications are often limited due to nephrotoxic effects. Objective: This study investigated the protective effects of aqueous-ethanol extract of Tamarindus indica L. (Leguminosae) fruits against gentamicin-induced renal toxicity. Materials and methods: A daily dose of 200 mg/kg of 70% aqueous-ethanol extract derived from T. indica was employed in male rabbits as a co-therapy with gentamicin (80 mg/kg) for a period of three weeks. Serum and urinary renal function parameters and histological assessments were carried out and compared with one way analysis of variance (Graphpad prism version 5.00, Graphpad Software, San Diego, CA). Results: The results showed that gentamicin-treated animals had significantly elevated blood urea nitrogen (54.1 ± 2.6 mg/dl), serum creatinine (4.0 ± 0.1 mg/dl), serum uric acid (2.3 ± 0.1 mg/dl) and urinary protein excretion (3.8 ± 0.3 mg/dl) with a fall in body weight (10 ± 1%), creatinine clearance (0.7 ± 0.09 ml/min), serum potassium (3.4 ± 0.1 mEq/l), serum calcium (7.6 ± 0.2 mg/dl), urinary volume (126 ± 9 ml/24 h) and urinary lactate dehydrogenase secretion (103.1 ± 4.2 U/l). However, animals treated by co-therapy with gentamicin and T. indica had significantly improved renal structure and function. Discussion and conclusion: Co-therapy of 200 mg/kg/d of T. indica for a period of three weeks successfully prevented functional and morphological derangements caused by gentamicin as assessed by different renal function parameters and histological examinations.

  7. Integrated transcriptomic and proteomic evaluation of gentamicin nephrotoxicity in rats

    Energy Technology Data Exchange (ETDEWEB)

    Com, Emmanuelle, E-mail: emmanuelle.com@univ-rennes1.fr [sanofi-aventis R and D, Disposition Safety and Animal Research, Vitry-sur-Seine (France); INSERM U625, Proteomics Core Facility Biogenouest, Rennes (France); Boitier, Eric; Marchandeau, Jean-Pierre [sanofi-aventis R and D, Disposition Safety and Animal Research, Vitry-sur-Seine (France); Brandenburg, Arnd [Genedata AG, Basel (Switzerland); Schroeder, Susanne [Nycomed GmbH, Barsbüttel (Germany); Hoffmann, Dana; Mally, Angela [University of Würzburg, Department of Toxicology, University of Würzburg, Würzburg (Germany); Gautier, Jean-Charles [sanofi-aventis R and D, Disposition Safety and Animal Research, Vitry-sur-Seine (France)

    2012-01-01

    Gentamicin is an aminoglycoside antibiotic, which induces renal tubular necrosis in rats. In the context of the European InnoMed PredTox project, transcriptomic and proteomic studies were performed to provide new insights into the molecular mechanisms of gentamicin-induced nephrotoxicity. Male Wistar rats were treated with 25 and 75 mg/kg/day subcutaneously for 1, 3 and 14 days. Histopathology observations showed mild tubular degeneration/necrosis and regeneration and moderate mononuclear cell infiltrate after long-term treatment. Transcriptomic data indicated a strong treatment-related gene expression modulation in kidney and blood cells at the high dose after 14 days of treatment, with the regulation of 463 and 3241 genes, respectively. Of note, the induction of NF-kappa B pathway via the p38 MAPK cascade in the kidney, together with the activation of T-cell receptor signaling in blood cells were suggestive of inflammatory processes in relation with the recruitment of mononuclear cells in the kidney. Proteomic results showed a regulation of 163 proteins in kidney at the high dose after 14 days of treatment. These protein modulations were suggestive of a mitochondrial dysfunction with impairment of cellular energy production, induction of oxidative stress, an effect on protein biosynthesis and on cellular assembly and organization. Proteomic results also provided clues for potential nephrotoxicity biomarkers such as AGAT and PRBP4 which were strongly modulated in the kidney. Transcriptomic and proteomic data turned out to be complementary and their integration gave a more comprehensive insight into the putative mode of nephrotoxicity of gentamicin which was in accordance with histopathological findings. -- Highlights: ► Gentamicin induces renal tubular necrosis in rats. ► The mechanisms of gentamicin nephrotoxicity remain still elusive. ► Transcriptomic and proteomic analyses were performed to study this toxicity in rats. ► Transcriptomic and proteomic

  8. Toxicity of gentamicin in red-tailed hawks.

    Science.gov (United States)

    Bird, J E; Walser, M M; Duke, G E

    1983-07-01

    Gentamicin sulfate at dosage levels of 10 and 20 mg/kg of body weight was administered twice daily IV to red-tailed hawks. Clinical signs, water consumption, and changes in blood chemical values were monitored. Tissues were examined grossly and ultrastructurally, using light and electron microscopy. Clinical signs of weakness and apnea were attributed to gentamicin-induced neuromuscular blockade in the 20-mg/kg group. Serum values of aspartate transaminase, alanine transaminase, cholesterol, inorganic phosphorus, total protein, albumin, and uric acid increased in some birds. There was a decrease in periodic acid-Schiff staining of proximal tubular brush borders. Increased numbers of cytoplasmic lysosomes, many of which contained myelin figures, in renal epithelial cells were seen at the ultrastructural level. All birds given 20 mg/kg died. Both dosage levels were considered toxic in red-tailed hawks.

  9. Solvent density mode instability in non-polar solutions

    Indian Academy of Sciences (India)

    Susmita Kar; Ranjit Biswas; J Chakrabarti

    2008-08-01

    We analyse the origin of the multiple long time scales associated with the long time decay observed in non-polar solvation dynamics by linear stability analysis of solvent density modes where the effects of compressibility and solvent structure are systematically incorporated. The coupling of the solute–solvent interactions at both ground and excited states of the solute with the compressibility and solvent structure is found to have important effects on the time scales. The present theory suggests that the relatively longer time constant is controlled by the solvent compressibility, while the solvent structure at the nearest-neighbour length scale dominates the shorter time constant.

  10. Photonic Crystal Polarizing and Non-Polarizing Beam Splitters

    Institute of Scientific and Technical Information of China (English)

    GUAN Chun-Ying; SHI Jin-Hui; YUAN Li-Bo

    2008-01-01

    A polarizing beam splitter(PBS)and a non-polarizing beam splitter(NPBS)based on a photonic crystal(PC)directional coupler are demonstrated.The photonic crystal directional coupler consists of a hexagonal lattice of dielectric pillars in air and has a complete photonic band gap.The photonic band structure and the band gap map are calculated using the plane wave expansion(PWE)method.The splitting properties of the splitter are investigated numerically using the finite difference time domain(FDTD)method.

  11. Protective effect of alpha-linolenic acid on gentamicin-induced ototoxicity in mice.

    Science.gov (United States)

    Kaplan, Halil Mahir; Şingirik, Ergin; Erdoğan, Kıvılcım Eren; Doran, Figen

    2017-07-31

    Alpha-linolenic acid is one of the fatty acids known as omega 3. Previous studies have shown the antioxidant and anti-inflammatory effects of alpha-linolenic acid, which prevented cell damage by inhibiting apoptotic pathway. Also, it is known that gentamicin activates apoptotic mediators and causes necrosis in the kidney. Due to this reason, we planned a study to evaluate the protective effects of alpha-linolenic acid on gentamicin induced ototoxicity by evaluating inflammation and apoptotic mediators. For this purpose, 100 mg/kg gentamicin (i.p; intraperitoneally) and 200 mg/kg alpha-linolenic acid (gavage) are administered to mice for 9 days. On 9th and 10th days, rotarod performance was assessed to test the effect of gentamicin and alpha-linolenic acid treatment on the motor coordination of mice. Gentamicin treatment decreased fall latency of mice and gentamicin treatment together with alpha-linolenic acid increased fall latency of mice. Gentamicin treatment also increased expression of phospholipase A2(plA2), cyclooxygenase-2(COX-2) and inducible nitric oxide syntheses (iNOS). Furthermore, it increased Bax and caspase-3, which are proapoptotic proteins and decreased bcl-2 that is an antiapoptotic protein. Gentamicin treatment together alpha-linolenic acid recovered the change of expression of these enzymes. In conclusion, this study showed that alpha-linolenic acid will be useful to prevent gentamicin-induced ototoxicity by inhibiting apoptosis and inflammation.

  12. Electrophoretic Retardation of Colloidal Particles in Nonpolar Liquids

    Directory of Open Access Journals (Sweden)

    Filip Strubbe

    2013-04-01

    Full Text Available We have measured the electrophoretic mobility of single, optically trapped colloidal particles, while gradually depleting the co-ions and counterions in the liquid around the particle by applying a dc voltage. This is achieved in a nonpolar liquid, where charged reverse micelles act as co-ions and counterions. By increasing the dc voltage, the mobility first increases when the concentrations of co-ions and counterions near the particle start to decrease. At sufficiently high dc voltage (around 2 V, the mobility reaches a saturation value when the co-ions and counterions are fully separated. The increase in mobility is larger when the equilibrium ionic strength is higher. The dependence of the experimental data on the equilibrium ionic strength and on the applied voltage is in good agreement with the standard theory of electrophoretic retardation, assuming that the bare particle charge remains constant. This method is useful for studying the electrophoretic retardation effect and charging mechanisms for nonpolar colloids, and it sheds light on previously unexplained particle acceleration in electronic ink devices.

  13. Observation of water dangling OH bonds around dissolved nonpolar groups.

    Science.gov (United States)

    Perera, P N; Fega, K R; Lawrence, C; Sundstrom, E J; Tomlinson-Phillips, J; Ben-Amotz, Dor

    2009-07-28

    We report the experimental observation of water dangling OH bonds in the hydration shells around dissolved nonpolar (hydrocarbon) groups. The results are obtained by combining vibrational (Raman) spectroscopy and multivariate curve resolution (MCR), to reveal a high-frequency OH stretch peak arising from the hydration shell around nonpolar (hydrocarbon) solute groups. The frequency and width of the observed peak is similar to that of dangling OH bonds previously detected at macroscopic air-water and oil-water interfaces. The area of the observed peak is used to quantify the number of water dangling bonds around hydrocarbon chains of different length. Molecular dynamics simulation of the vibrational spectra of water molecules in the hydration shell around neopentane and benzene reveals high-frequency OH features that closely resemble the experimentally observed dangling OH vibrational bands around neopentyl alcohol and benzyl alcohol. The red-shift of approximately 50 cm(-1) induced by aromatic solutes is similar to that previously observed upon formation of a pi-H bond (in low-temperature benzene-water clusters).

  14. Microsomal protein synthesis inhibition: an early manifestation of gentamicin nephrotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, W.M.; Mela-Riker, L.M.; Houghton, D.C.; Gilbert, D.N.; Buss, W.C.

    1988-08-01

    Aminoglycoside antibiotics achieve bacterial killing by binding to bacterial ribosomes and inhibiting protein synthesis. To examine whether similar mechanisms could be present in renal tubular cells prior to the onset of overt proximal tubular necrosis due to these drugs, we isolated microsomes from Fischer rats given 20 mg/kg gentamicin every 12 h subcutaneously for 2 days and from vehicle-injected controls. Concomitant studies of renal structure, function, and mitochondrial respiration were carried out. (3H)leucine incorporation into renal microsomes of treated animals was reduced by 21.9% (P less than 0.01), whereas brain and liver microsomes from the same animals were unaffected. Gentamicin concentration in the renal microsomal preparation was 56 micrograms/ml, a value 7- to 10-fold above concentrations necessary to inhibit bacterial growth. Conventional renal function studies were normal (blood urea, serum creatinine, creatinine clearance). Treated animals showed only a mild reduction of inulin clearance, 0.71 compared with 0.93 ml.min-1.100 g-1 in controls (P less than 0.05), and an increase in urinary excretion of N-acetylglucosaminidase of 20 compared with 14.8 units/l (P less than 0.05). Renal slice transport of p-aminohippuric acid, tetraethylammonium, and the fractional excretion of sodium were well preserved. There was no evidence, as seen by light microscopy, of proximal tubular necrosis. Mitochondrial cytochrome concentrations were normal and respiratory activities only slightly reduced. Processes similar to those responsible for bacterial killing could be involved in experimental gentamicin nephrotoxicity before overt cellular necrosis.

  15. Gentamicin-mediated ototoxicity and nephrotoxicity: A clinical trial study

    Directory of Open Access Journals (Sweden)

    Parviz Saleh

    2016-01-01

    Full Text Available Background: Aminoglycosides and mainly gentamicin are the most important antimicrobial agents. Two different methods of administration exist: Single and multiple doses. There has always been a controversy about the less harmful administration method, to minimize adverse effects of gentamicin - deafness and renal insufficiency. In this study, it was aimed to compare two different methods of administration to figure out the least harmful treatment method. Materials and Methods: In a clinical study, eighty patients aged 12-55 years who were admitted with sepsis syndrome were included in the study; they were divided into two groups: The first group received single-dose treatment (5 mg/kg whereas the second group was treated with multiple doses (1.7 mg/kg three times a day of gentamicin. Results: The results show that blood urea nitrogen (BUN and creatinine (CR levels were decreased in the first group. Both blood urea nitrogen and creatinine and also mean glomerular filtration rate was increased in the same group. In the second group, mean BUN and CR levels were increased while the GFR was decreased in the same group. There was also a gradual increase in GFR in the first group. GFR <80 was decreased from 20% to 5.1% in the first group while increased from 5% to 27.5% in the second group. Results of audiometric studies show 6.1% hearing problem in the first group and 12.8% in the second one. Conclusions: Results of the present study showed that nephrotoxicity and ototoxicity are minimized in single-dose administration compared to multiples doses.

  16. Controlled Delivery of Gentamicin Using Poly(3-hydroxybutyrate Microspheres

    Directory of Open Access Journals (Sweden)

    Ipsita Roy

    2011-07-01

    Full Text Available Poly(3-hydroxybutyrate, P(3HB, produced from Bacillus cereus SPV using a simple glucose feeding strategy was used to fabricate P(3HB microspheres using a solid-in-oil-water (s/o/w technique. For this study, several parameters such as polymer concentration, surfactant and stirring rates were varied in order to determine their effect on microsphere characteristics. The average size of the microspheres was in the range of 2 µm to 1.54 µm with specific surface areas varying between 9.60 m2/g and 6.05 m2/g. Low stirring speed of 300 rpm produced slightly larger microspheres when compared to the smaller microspheres produced when the stirring velocity was increased to 800 rpm. The surface morphology of the microspheres after solvent evaporation appeared smooth when observed under SEM. Gentamicin was encapsulated within these P(3HB microspheres and the release kinetics from the microspheres exhibiting the highest encapsulation efficiency, which was 48%, was investigated. The in vitro release of gentamicin was bimodal, an initial burst release was observed followed by a diffusion mediated sustained release. Biodegradable P(3HB microspheres developed in this research has shown high potential to be used in various biomedical applications.

  17. 21 CFR 524.1044b - Gentamicin sulfate, betamethasone valerate otic solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Gentamicin sulfate, betamethasone valerate otic solution. 524.1044b Section 524.1044b Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... NEW ANIMAL DRUGS § 524.1044b Gentamicin sulfate, betamethasone valerate otic solution....

  18. The release of gentamicin from acrylic bone cements in a simulated prosthesis-related interfacial gap

    NARCIS (Netherlands)

    Hendriks, JGE; Neut, D; van Horn, [No Value; van der Mei, HC; Busscher, HJ

    2003-01-01

    Gentamicin is added to polymethylmethacrylate bone cements in orthopedics as a measure against infection in total joint arthroplasties. Numerous studies have been published on gentamicin release from bone cements, but none have been able to estimate the local concentrations in the prosthesis-related

  19. Coherent Control of Vibrational State Population in a Nonpolar Molecule

    CERN Document Server

    Picón, A; Jaron-Becker, A; Becker, A; 10.1103/PhysRevA.83.023412

    2011-01-01

    A coherent control scheme for the population distribution in the vibrational states of nonpolar molecules is proposed. Our theoretical analysis and results of numerical simulations for the interaction of the hydrogen molecular ion in its electronic ground state with an infrared laser pulse reveal a selective two-photon transition between the vibrational states via a coupling with the first excited dissociative state. We demonstrate that for a given temporal intensity profile the population transfer between vibrational states, or a superposition of vibrational states, can be made complete for a single chirped pulse or a train of chirped pulses, which accounts for the accumulated phase difference due to the AC Stark effect. Effects of a spatial intensity (or, focal) averaging are discussed.

  20. Polarity inversion in polar-nonpolar-polar heterostructures.

    Science.gov (United States)

    Cho, S; Youn, S J; Kim, Y; DiVenere, A; Wong, G K; Freeman, A J; Ketterson, J B

    2001-09-17

    We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations.

  1. Gentamicin Binds to Megalin as a Competitive Inhibitor Using the Common Ligand Binding Motif of Complement Type Repeats

    DEFF Research Database (Denmark)

    Dagil, Robert; O'Shea, Charlotte; Nykjaer, Anders

    2012-01-01

    Gentamicin is an aminoglycoside widely used in treatments of, in particular, enterococcal, mycobacterial, and severe Gram-negative bacterial infections. Large doses of gentamicin cause nephrotoxicity and ototoxicity, entering the cell via the receptor megalin. Until now, no structural information...

  2. Effects of gentamicin on the recovery of renal function after unilateral hydronephrosis

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Nobumitsu [Ehime Univ., Shigenobu (Japan). School of Medicine

    2002-06-01

    Urinary tract infection is one of complications in hydronephrosis, and antibiotics such as gentamicin are indicated for the treatment. However, gentamicin is known to cause drug-induced nephropathy. Using a rat kidney model, we investigated the effects of gentamicin treatment on the functional recovery from unilateral hydronephrosis. Quantitative separate renal function study by means of Technetium-99m DMSA renoscintigraphy revealed that contralateral kidney was affected by the treatment right after the release of complete ureteral obstruction. Moreover, in the case of incomplete ureteral obstruction, bilateral kidneys were affected by the treatment. Morphological studies using in situ DNA3' -end labeling and immunohistochemical methods showed that regeneration in the bilateral kidney followed gentamicin treatment right after the release. These results suggest that we should take account of separate renal function failure after gentamicin administration in the perihydronephrotic periods. (author)

  3. Direct laser light enhancement of susceptibility of bacteria to gentamicin antibiotic

    Science.gov (United States)

    Reznick, Yana; Banin, Ehud; Lipovsky, Anat; Lubart, Rachel; Zalevsky, Zeev

    2011-11-01

    ObjectivesTo test the effect of pulsed (Q-switched) and continuous wave (CW) laser light at wavelength of 532 nm on the viability of free-living stationary phase bacteria with and without gentamicin (an antibiotic) treatment. MethodsFree living stationary phase gram negative bacteria ( Pseudomonas aeruginosa strain PAO1) was immersed in Luria Broth (LB) solution and exposed to Q-switched and CW lasers with and without the addition of the antibiotic gentamicin. Cell viability was determined at different time points. ResultsLaser treatment alone did not reduce cell viability compared to untreated control and the gentamicin treatment alone only resulted in a 0.5 log reduction in the viable count for P. aeruginosa. The combined laser and gentamicin treatment, however, resulted in a synergistic effect and viability was reduced by 8 logs for P. aeruginosa PAO1. ConclusionsCombination of laser light with gentamicin shows an improved efficacy against P. aeruginosa.

  4. Analysis of current transport properties in nonpolar a-plane ZnO-based Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hogyoung [Seoul National University of Science and Technology, Seoul (Korea, Republic of); Kim, Haeri; Kim, Dongwook [Ewha Womans University, Seoul (Korea, Republic of)

    2014-09-15

    Using current-voltage (I - V) measurements, we investigated the temperature-dependent transport properties in Ag/nonpolar a-plane ZnO Schottky diodes. The bias-dependent ideality factors were altered by the different temperatures and showed a hump at lower temperatures. The series resistance of the diode depended on the temperatures, which was related to the number of free carriers contributing to the series resistance. For high forward bias, the slope m obtained from the lnI - lnV curves decreased with increasing temperature, assuring the space-charge-limited-current (SCLC) model controlled by an exponential distribution of traps. The reverse-biased current transport was associated with the Schottky effect, with a thermally-assisted tunneling for lower voltages and the Poole-Frenkel effect for higher voltages. The density of localized states (N{sub t}) was obtained by applying the theory of SCLC transport, which yielded a N{sub t} value of 8.32 x 10{sup 11} eV{sup -1}cm{sup -3}.

  5. Cost evaluation of therapeutic drug monitoring of gentamicin at a teaching hospital in Malaysia

    Directory of Open Access Journals (Sweden)

    Ibrahim MI

    2014-03-01

    Full Text Available Background: Therapeutic drug monitoring (TDM makes use of serum drug concentrations as an adjunct to decision-making. Preliminary data in our hospital showed that approximately one-fifth of all drugs monitored by TDM service were gentamicin. Objective: In this study, we evaluated the costs associated with providing the service in patients with bronchopneumonia and treated with gentamicin. Methods: We retrospectively collected data from medical records of patients admitted to the Hospital Universiti Sains Malaysia over a 5-year period. These patients were diagnosed with bronchopneumonia and were on gentamicin as part of their treatment. Five hospitalisation costs were calculated; (i cost of laboratory and clinical investigations, (ii cost associated with each gentamicin dose, (iii fixed and operating costs of TDM service, (iv cost of providing medical care, and (v cost of hospital stay during gentamicin treatment. Results: There were 1920 patients admitted with bronchopneumonia of which 67 (3.5% had TDM service for gentamicin. Seventy-three percent (49/67 patients were eligible for final analysis. The duration of gentamicin therapy ranged from 3 to 15 days. The cost of providing one gentamicin assay was MYR25, and the average cost of TDM service for each patient was MYR104. The average total hospitalisation cost during gentamicin treatment for each patient was MYR442 (1EUR approx. MYR4.02. Conclusion: Based on the hospital perspective, in patients with bronchopneumonia and treated with gentamicin, the provision of TDM service contributes to less than 25% of the total cost of hospitalization.

  6. Protective effect of naringenin against gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    Fouad, Amr A; Albuali, Waleed H; Zahran, Ahmed; Gomaa, Wafaey

    2014-09-01

    The protective effect of naringenin, a flavonoid compound isolated from citrus fruits, was investigated against nephrotoxicity induced by gentamicin (80mgkg(-1)/day, i.p., for eight days) in rats. Naringenin treatment (50mgkg(-1)/day, p.o.) was administered for eight days, starting on the same day of gentamicin administration. Gentamicin caused significant elevations of serum creatinine, and kidney tissue levels of malondialdehyde, nitric oxide, and interleukin-8, and a significant decrease in renal glutathione peroxidase activity. Naringenin treatment significantly ameliorated the changes in the measured biochemical parameters resulted from gentamicin administration. Also, naringenin markedly attenuated the histopathological renal tissue injury observed with gentamicin. Immunohistochemical examinations showed that naringenin significantly reduced the gentamicin-induced expression of kidney injury molecule-1, vascular endothelial growth factor, inducible nitric oxide synthase, and caspase-9, and increased survivin expression in the kidney tissue. It was concluded that naringenin, through its antioxidant and anti-inflammatory effects, may represent a therapeutic option to protect against gentamicin nephrotoxicity.

  7. Agmatine improves renal function in gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    El-Kashef, Dalia H; El-Kenawi, Asmaa E; Abdel Rahim, Mona; Suddek, Ghada M; Salem, Hatem A

    2016-03-01

    The present study was designed to explore the possible protective effects of agmatine, a known nitric oxide (NO) synthase inhibitor, against gentamicin-induced nephrotoxicity in rats. For this purpose, we quantitatively evaluated gentamicin-induced renal structural and functional alterations using histopathological and biochemical approaches. Furthermore, the effect of agmatine on gentamicin-induced hypersensitivity of urinary bladder rings to acetylcholine (ACh) was evaluated. Twenty-four male Wistar albino rats were randomly divided into 3 groups, namely control, gentamicin (100 mg/kg, i.p.), and gentamicin plus agmatine (40 mg/kg, orally). At the end of the study, all rats were sacrificed and then blood and urine samples and kidneys were taken. Administration of agmatine significantly decreased kidney/body mass ratio, serum creatinine, lactate dehydrogenase (LDH), renal malondialdehyde (MDA), myeloperoxidase (MPO), NO, and tumor necrosis factor-alpha (TNF-α) while it significantly increased creatinine clearance and renal superoxide dismutase (SOD) activity when compared with the gentamicin-treated group. Additionally, agmatine ameliorated tissue morphology as evidenced by histological evaluation and reduced the responses of isolated bladder rings to ACh. Our study indicates that agmatine administration with gentamicin attenuates oxidative-stress associated renal injury by reducing oxygen free radicals and lipid peroxidation, restoring NO level and inhibiting inflammatory mediators such as TNF-α.

  8. Effect of nettle (Urtica dioica) extract on gentamicin induced nephrotoxicity in male rabbits

    Institute of Scientific and Technical Information of China (English)

    Nadia Abdulkarim Salih

    2015-01-01

    To investigate the antioxidant effect of an orally administered ethanol extract of nettle (Urtica dioica) and its protective role in preventing or ameliorating oxidative stress as a major factor in gentamicin-induced nephrotoxicity in male rabbits. Methods: Twenty rabbits were divided into 4 equal groups: (G1) control group, (G2) gentamicin treated group (100 mg/kg), (G3) nettle treated group (100 mg/kg), (G4) combination treated group with both gentamicin (100 mg/kg) and nettle (100 mg/kg) for 10 days. The antioxidant properties of nettle were evaluated using different antioxidant tests, such as determination of glutathione and malondialdehyde levels and total phenolic content analysis. Results: Biochemical and histopathological study revealed that gentamicin caused nephrotoxicity observed clearly in the histopathological section of the kidney in the gentamicin treated group. Serum creatinine and blood urea nitrogen were biochemical indicators for nephrotoxicity which increased significantly in gentamicin treated group; other groups have no significant change in these two parameters. Nettle extract protected the rabbits from alteration in the level of blood urea nitrogen and serum creatinine when given after inducing of gentamicin nephrotoxicity. The nettle treated group showed a great effect as an antioxidant factor by increasing the glutathione level and reducing malondialdehyde level. No significant changes in biochemical parameters and no renal histopathological changes observed in the groups treated with nettle extract, which meant nettle had powerful antioxidant activity. Conclusions: Therefore, it can be assumed that the nephroprotective effect shown by nettle in gentamicin-induced nephrotoxicity can reserve intracellular levels of biological pathways and supportively enhance excretion of toxic levels of gentamicin.

  9. Protective effect of allicin against gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    El-Kashef, Dalia H; El-Kenawi, Asmaa E; Suddek, Ghada M; Salem, Hatem A

    2015-12-01

    In this study, the modulator effect of allicin on the oxidative nephrotoxicity of gentamicin in the kidneys of rats was investigated by determining indices of lipid peroxidation and the activities of antioxidant enzymes, as well as by histological analyses. Furthermore, the effect of allicin on gentamicin induced hypersensitivity of urinary bladder rings to ACh was estimated. Twenty-four male Wistar albino rats were randomly divided into three groups, control, gentamicin (100mg/kg, i.p.) and gentamicin+allicin (50mg/kg, orally). At the end of the study, all rats were sacrificed and then urine, blood samples and kidneys were taken. Gentamicin administration caused a severe nephrotoxicity as evidenced by an elevated kidney/body weight ratio, serum creatinine, blood urea nitrogen (BUN), serum lactate dehydrogenase (LDH) and proteinuria with a reduction in serum albumin and creatinine clearance as compared with control group. In addition, a significant increase in renal contents of malondialdehyde (MDA), myeloperoxidase (MPO), nitric oxide (NOx) and tumor necrosis factor-alpha (TNF-α) concomitantly with a significant decrease in renal reduced glutathione (GSH) and superoxide dismutase (SOD) activities was detected upon gentamicin injection. Exposure to gentamicin increased the sensitivity of isolated urinary bladder rings to ACh and induced acute renal tubular epithelial cells necrosis. Administration of allicin significantly decreased kidney/body weight ratio, serum creatinine, LDH, renal MDA, MPO, NOx and TNF-α while it significantly increased creatinine clearance, renal GSH content and renal SOD activity when compared to gentamicin-treated group. Additionally, allicin significantly reduced the responses of isolated bladder rings to ACh and ameliorated tissue morphology as evidenced by histological evaluation. Our study indicates that allicin exerted protection against structural and functional damage induced by gentamicin possibly due to its antioxidant, anti

  10. Effect of nettle(Urtica dioica) extract on gentamicin induced nephrotoxicity in male rabbits

    Institute of Scientific and Technical Information of China (English)

    Nadia; Abdulkarim; Salih

    2015-01-01

    Objective:To investigate the antioxidant ef ect of an orally administered ethanol extract of nettle(Urtica dioica) and its protective role in preventing or ameliorating oxidative stress as a major factor in gentamicin-induced nephrotoxicity in male rabbits. Methods: Twenty rabbits were divided into 4 equal groups:(G1) control group,(G2) gentamicin treated group(100 mg/kg),(G3) nettle treated group(100 mg/kg),(G4) combination treated group with both gentamicin(100 mg/kg) and nettle(100 mg/kg) for 10 days. The antioxidant properties of nettle were evaluated using dif erent antioxidant tests, such as determination of glutathione and malondialdehyde levels and total phenolic content analysis. Results: Biochemical and histopathological study revealed that gentamicin caused nephrotoxicity observed clearly in the histopathological section of the kidney in the gentamicin treated group. Serum creatinine and blood urea nitrogen were biochemical indicators for nephrotoxicity which increased signii cantly in gentamicin treated group; other groups have no signii cant change in these two parameters. Nettle extract protected the rabbits from alteration in the level of blood urea nitrogen and serum creatinine when given after inducing of gentamicin nephrotoxicity. The nettle treated group showed a great ef ect as an antioxidant factor by increasing the glutathione level and reducing malondialdehyde level. No signii cant changes in biochemical parameters and no renal histopathological changes observed in the groups treated with nettle extract, which meant nettle had powerful antioxidant activity. Conclusions: Therefore, it can be assumed that the nephroprotective ef ect shown by nettle in gentamicin-induced nephrotoxicity can reserve intracellular levels of biological pathways and supportively enhance excretion of toxic levels of gentamicin.

  11. Density and Phase State of a Confined Nonpolar Fluid

    Science.gov (United States)

    Kienle, Daniel F.; Kuhl, Tonya L.

    2016-07-01

    Measurements of the mean refractive index of a spherelike nonpolar fluid, octamethytetracylclosiloxane (OMCTS), confined between mica sheets, demonstrate direct and conclusive experimental evidence of the absence of a first-order liquid-to-solid phase transition in the fluid when confined, which has been suggested to occur from previous experimental and simulation results. The results also show that the density remains constant throughout confinement, and that the fluid is incompressible. This, along with the observation of very large increases (many orders of magnitude) in viscosity during confinement from the literature, demonstrate that the molecular motion is limited by the confining wall and not the molecular packing. In addition, the recently developed refractive index profile correction method, which enables the structural perturbation inherent at a solid-liquid interface and that of a liquid in confinement to be determined independently, was used to show that there was no measurable excess or depleted mass of OMCTS near the mica surface in bulk films or confined films of only two molecular layers.

  12. Design of non-polarizing thin film edge filters

    Institute of Scientific and Technical Information of China (English)

    GU Pei-fu; ZHENG Zhen-rong

    2006-01-01

    The separation between s- and p-polarization components invariably affects thin film edge filters used for tilted incidence and is a difficult problem for many applications, especially for optical communication. This paper presents a novel design method to obtain edge filters with non-polarization at incidence angle of 45°. The polarization separation at 50% transmittance for a long-wave-pass filter and a short-wave-pass filter is 0.3 nm and 0.1 nm respectively. The design method is based on a broadband Fabry-Perot thin-film interference filter in which the higher or lower interference band at both sides of the main transmittance peak can be used for initial design of long-wave-pass filter or short-wave-pass filter and then can be refined to reduce the transmittance ripples. The spacer 2H2L2H or 2L2H2L of the filter is usually taken. Moreover, the method for expanding the bandwidth of rejection and transmission is explained. The bandwidth of 200 nm for both rejection region and transmission band is obtained at wavelength 1550 nm. In this way, the long-wave-pass and short-wave-pass edge filters with zero separation between two polarization components can easily be fabricated.

  13. In vitro gentamicin release from bioactive Bhagelena implant against Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Aniek Setiya Budiatin

    2014-05-01

    Full Text Available Osteomyelitis is a bone-related infectious desease which is difficult to treat, because the antibiotic reaches the target is lower than the MIC and bacteria can €™t be eradicated. This condition can cause the bacteria become resistant. To solve this problem, we can use local antibiotics as BHAG(ELENA pellets implant, which can release gentamicin (GEN continuously for more than a day with a concentration greater than MIC. BHAG(ELENA pellet that have made contain BHA : GEL = 20 : 2 (dry state; GEN 10% and cross-linking with glutaraldehyde (GA 0,5%, cylindrical weigh 100 mg; 4 mm in diameter and 3.2 mm thick. The release of GEN from BHAG(ELENA pellet were tested in vitro, by soaking the pellet in phosphate buffer saline pH 7.4 at temperature 370C. The sample were sampled every day until 28 days. Then, the sample were tested by agar diffusion method that contain Staphylococcus aureus. Results showed that inhibition zone diameter greater than MIC GEN to S. aureus. Within 28 days, the release of GEN provide a total activity 99,24%, it showed that after 28 days, the pellets are still actively inhibit the bacterial growth. Furthermore, required to be tested in animal study (in vivo with a defect in the femoral bone then filled with BHAG(ELENA pellets as drug delivery system of GEN and bone fillers

  14. Metabolic Activation of Nonpolar Sediment Extracts Results in enhanced Thyroid Hormone Disrupting Potency

    NARCIS (Netherlands)

    Montano, M.; Weiss, J.; Hoffmann, L.; Gutleb, A.C.; Murk, A.J.

    2013-01-01

    Traditional sediment risk assessment predominantly considers the hazard derived from legacy contaminants that are present in nonpolar sediment extracts, such as polychlorinated biphenyls (PCBs), dioxins, furans (PCDD/Fs), and polyaromatic hydrocarbons (PAHs). Although in vivo experiments with these

  15. Adsorption of polar, nonpolar, and substituted aromatics to colloidal graphene oxide nanoparticles

    NARCIS (Netherlands)

    Wang, Fang; Haftka, Joris J H; Sinnige, Theo L.; Hermens, Joop L M; Chen, Wei

    2014-01-01

    We conducted batch adsorption experiments to understand the adsorptive properties of colloidal graphene oxide nanoparticles (GONPs) for a range of environmentally relevant aromatics and substituted aromatics, including model nonpolar compounds (pyrene, phenanthrene, naphthalene, and 1,3-dichlorobenz

  16. Functional and anatomic alterations in the gentamicin-damaged vestibular system in the guinea pig

    NARCIS (Netherlands)

    Oei, MLYM; Segenhout, HM; Dijk, T; Stokroos, [No Value; van der Want, TJL; Albers, FWJ

    2004-01-01

    Hypothesis: The purpose of this study was to investigate the expected functional and morphologic effect of gentamicin on the vestibular system simultaneously by measurement of vestibular evoked potentials and electron microscopic evaluation. Background: Vestibular short-latency evoked potentials to

  17. Gentamicin modified chitosan film with improved antibacterial property and cell biocompatibility.

    Science.gov (United States)

    Liu, Yang; Ji, Peihong; Lv, Huilin; Qin, Yong; Deng, Linhong

    2017-05-01

    Gentamicin modified chitosan film (CS-GT) was produced using a three-step procedure comprising: (i) the chitosan solution was air-dried to form a chitosan (CS) film, (ii) using citric acid to generate the amide and carboxyl groups on the surface of CS, (iii) the CS with surface carboxyl groups was modified by grafting of gentamicin. After modification, this CS-GT film has excellent hydrophilicity and biocompatibility. It is very evident that the gentamicin grafting treatment significantly improves the antibacterial properties of the CS film. Our preliminary results suggest that this novel gentamicin modified chitosan film, which can be prepared in large quantities and at low cost, should have potential application in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Simultaneous immobilization of heparin and gentamicin on polypropylene textiles: a dual therapeutic activity.

    Science.gov (United States)

    Degoutin, Stéphanie; Jimenez, Maude; Chai, Feng; Pinalie, Thibaut; Bellayer, Severine; Vandenbossche, Marianne; Neut, Christel; Blanchemain, Nicolas; Martel, Bernard

    2014-11-01

    The aim of this work was to prepare a nonwoven polypropylene (PP) textile functionalized with bioactive molecules in order to improve simultaneously anticoagulation and antibacterial properties. The immobilization of either heparin (anticoagulation agent) or gentamicin (aminoglycoside class antibiotic) alone has already been proven to be effective on PP nonwoven textiles. In this work, we managed to go further, by immobilizing both heparin and gentamicin at the same time on one unique textile. A successive immersion in different heparin and gentamicin bathes successfully led to a dual drug coated textile, as confirmed by several characterization techniques (Fourier transform infrared-attenuated total reflectance, X-ray photoelectron spectroscopy, and scanning electron microscopy). The immobilization times were varied in order to determine the best compromise between cytocompatibility, anticoagulant effect, and antimicrobial activity. Short immersion times in gentamicin solutions confer very good antimicrobial activity to the textile and avoid cytotoxicity, whereas long immersion times in heparin solution were necessary to observe a significant anticoagulant effect.

  19. Pharmacokinetics and clinical evaluations of gentamicin-induced nephrotoxicity in puppies

    Directory of Open Access Journals (Sweden)

    Fidelis A. Gberindyer

    2015-08-01

    Conclusion: These suggest the risk of nephrotoxicity following treatment with gentamicin beyond 5 consecutive days irrespective of the dosing interval in puppies. [Int J Basic Clin Pharmacol 2015; 4(4.000: 691-696

  20. Acousto-optic modulation and deflection of terahertz electromagnetic radiation in nonpolar liquids

    Science.gov (United States)

    Nikitin, P. A.; Voloshinov, V. B.; Gerasimov, V. V.; Knyazev, B. A.

    2017-07-01

    The results of a series of experiments on controlled deflection of electromagnetic radiation of a free-electron laser upon diffraction by an acoustic wave in nonpolar liquids are presented. Acoustic and optical properties of liquids that are transparent in the terahertz range are discussed. It is demonstrated that nonpolar liquids may turn out to be a more efficient acousto-optic interaction medium than dielectric crystals or semiconductors.

  1. Protective effect of lycopene on gentamicin-induced oxidative stress and nephrotoxicity in rats.

    Science.gov (United States)

    Karahan, I; Ateşşahin, A; Yilmaz, S; Ceribaşi, A O; Sakin, F

    2005-11-15

    A potential therapeutic approach to protect or reverse gentamicin-induced oxidative stress and nephrotoxicity would have more importance for clinical consequences. Therefore, the present study was designed to investigate the possible protective effects of lycopene against gentamicin-induced renal damage in rats. Male Sprague-Dawley rats were divided into four groups of six rats in each one; first group served as control. The other groups were treated intraperitoneally with gentamicin alone (100 mg kg(-1) per day) for six successive days, gentamicin for 6 days following 10 days of orally lycopene (4 mg kg(-1) per day) pre-treatment and 6-days of simultaneous lycopene and gentamicin. Biochemical and histopathological examinations were utilized for evaluation of the oxidative stress and renal nephrotoxicity. Creatinine, urea, Na(+) and K(+) levels in plasma and malondialdehyde (MDA), reduced glutathione (GSH) levels and glutathione peroxidase (GSH-Px) and catalase (CAT) activities were determined in kidney tissue. Administration of gentamicin to rats induced a marked renal failure, characterized by a significant increase in plasma creatinine and urea concentrations. The animals treated with gentamicin alone showed a significantly higher kidney MDA and lower GSH-Px and CAT activities but unaffected GSH concentrations when compared with the control group. Pre-treatment with lycopene produced amelioration in biochemical indices of nephrotoxicity in plasma. However, little changes were observed in the kidney MDA and GSH levels and GSH-Px and CAT activities when compared with the gentamicin treated group. The histological structures of the renal proximal tubules showed similar patterns. On the other hand, administration of simultaneous lycopene to rats produced amelioration in MDA and GSH levels and GSH-Px and CAT activities when compared with gentamicin group. In addition, simultaneous lycopene was found to reduce the degree of kidney tissue damage in histopathological

  2. Critical concentration of ion-pairs formation in nonpolar media.

    Science.gov (United States)

    Dukhin, Andrei

    2014-07-01

    It is known that nonpolar liquids can be ionized by adding surfactants, either ionic or nonionic. Surfactant molecules serve as solvating agents, building inverse micelles around ions, and preventing their association back into neutral molecules. According to the Bjerrum-Onsager-Fuoss theory, these inverse micelle ions should form "ion pairs." This, in turn, leads to nonlinear dependence of the conductivity on the concentration. Surprisingly, ionic surfactants exhibit linear conductivity dependence, which implies that these inverse micelle ions do not form ion pairs. Theory predicts the existence of two ionic strength ranges, which are separated by a certain critical ion concentration. Ionic strength above the critical one is proportional to the square root of the ion concentration, whereas it becomes linear below the critical concentration. Critical ion concentration lies within the range of 10(-11) -10(-7) mol/L when ion size ranges from 1 to 3 nm. Critical ion concentration is related, but not equal, to a certain surfactant concentration (critical concentration of ion-pairs formation (CIPC)) because only a fraction of the surfactant molecules is incorporated into the micelles ions. The linear conductivity dependence for ionic surfactants indicates that the corresponding CIPC is above the range of studied concentrations, perhaps, due to rather large ion size. The same linearity is a sign that charged inverse micelles structure and fraction are concentration independent due to strong charge-dipole interaction in the charge micelle core. This also proves that CIPC is independent of critical concentration of micelle formation. Nonionic surfactants, on the other hand, exhibit nonlinear conductivity dependence apparently due to smaller ion sizes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Effect of cyclooxygenase inhibitors on gentamicin-induced nephrotoxicity in rats

    Directory of Open Access Journals (Sweden)

    Hosaka E.M.

    2004-01-01

    Full Text Available The frequent use of nonsteroidal anti-inflammatory drugs (NSAID in combination with gentamicin poses the additional risk of nephrotoxic renal failure. Cyclooxygenase-1 (COX-1 is the main enzyme responsible for the synthesis of renal vasodilator prostaglandins, while COX-2 participates predominantly in the inflammatory process. Both are inhibited by non-selective NSAID such as indomethacin. Selective COX-2 inhibitors such as rofecoxib seem to have fewer renal side effects than non-selective inhibitors. The objective of the present study was to determine whether the combined use of rofecoxib and gentamicin can prevent the increased renal injury caused by gentamicin and indomethacin. Male Wistar rats (250-300 g were treated with gentamicin (100 mg/kg body weight, ip, N = 7, indomethacin (5 mg/kg, orally, N = 7, rofecoxib (1.4 mg/kg, orally, N = 7, gentamicin + rofecoxib (100 and 1.4 mg/kg, respectively or gentamicin + indomethacin (100 and 5 mg/kg, respectively, N = 8 for 5 days. Creatinine clearance and alpha-glutathione-S-transferase concentrations were used as markers of renal injury. Animals were anesthetized with ether and sacrificed for blood collection. The use of gentamicin plus indomethacin led to worsened renal function (0.199 ± 0.019 ml/min, as opposed to the absence of a nephrotoxic effect of rofecoxib when gentamicin plus rofexicob was used (0.242 ± 0.011 ml/min. These results indicate that COX-2-selective inhibitors can be used as an alternative treatment to conventional NSAID, especially in situations in which risk factors for nephrotoxicity are present.

  4. Protective Effects of Houttuynia cordata Thunb. on Gentamicin-induced Oxidative Stress and Nephrotoxicity in Rats

    OpenAIRE

    Kang, Changgeun; Lee, Hyungkyoung; Hah, Do-Yun; Heo, Jung Ho; Kim, Chung Hui; Kim, Euikyung; Kim, Jong Shu

    2013-01-01

    Development of a therapy providing protection from, or reversing gentamicin-sulfate (GS)-induced oxidative stress and nephrotoxicity would be of great clinical significance. The present study was designed to investigate the protective effects of Houttuynia cordata Thunb. (HC) against gentamicin sulfate-induced renal damage in rats. Twenty-eight Sprague-Dawley rats were divided into 4 equal groups as follows: group 1, control; group 2, GS 100 mg/kg/d, intraperitoneal (i.p.) injection; group 3,...

  5. Comparative effect of olive oil and fish oil supplementation in combating gentamicin induced nephrotoxicity in rats

    OpenAIRE

    Rashid, Fouzia; M. Kaleem; Sheema; Bano, B.

    2005-01-01

    The present study is related to the comparative effects of fish oil and olive oil supplementation on gentamicin induced nephrotoxicity in rats. Three treatment groups (Pretrement, Co-treatment and post treatment) were chosen for the study. Nephrotoxicity in rats was induced by intraperitonial administration of gentamicin (80 mg/kg/d) for 3,5,7,10,& 12 consecutive days. The animals were sacrificed 12 hrs after last treatment in each group. The maximum nephrotoxicity was developed on 10 days tr...

  6. Protective Effects of Acupuncture Against Gentamicin-Induced Ototoxicity in Rats: Possible Role of Neurotrophin-3

    Science.gov (United States)

    Zhou, Ping; Ma, Weijun; Sheng, Ying; Duan, Maoli; Zhang, Xiaotong

    2017-01-01

    Background The aim of this study was to investigate the protective effects of acupuncture against gentamicin-induced ototoxicity and explore the possible protective role of neurotrophin-3 (NT-3). Material/Methods Twenty-four rats were divided randomly into 4 groups: control group, gentamicin group, neitinggong group, and tinggong group. Rats in the gentamicin, neitinggong, and tinggong groups received intraperitoneal injection of gentamicin (100 mg/kg) for 14 consecutive days. Rats in the neitinggong and tinggong groups further received acupuncture at neitinggong or tinggong acupoints once every 2 days for 20 days. Rats in the control group received intraperitoneal injection of saline. Auditory brainstem response (ABR) was tested in all rats on the day before treatment (day 0), and again on day 14 and day 20 to determine the average threshold value of ABR for each treatment group. The expression of NT-3 in the cochlear nucleus and the inferior colliculus nucleus were detected by immunohistochemical staining. Results The average threshold value of ABR was significantly higher in the gentamicin group as compared with that of the control group on day 14 (P0.05). However, the expression of NT-3 in the inferior colliculus nucleus in both the neitinggong and tinggong groups was significantly higher than that of the gentamicin group (P<0.01). Conclusions A decrease in NT-3 expression in the inferior colliculus nucleus may contribute to gentamicin-induced ototoxicity in rats. Acupuncture at neitinggong or tinggong acupoints effectively improved hearing, which was attributed partially to the rescue of NT-3 expression in the inferior colliculus nucleus. Therefore, preserving NT-3 expression in the auditory system may be a viable strategy to counteract gentamicin-induced ototoxicity. PMID:28121979

  7. The influence of non-polar lipids on tear film dynamics

    KAUST Repository

    Bruna, M.

    2014-04-04

    © 2014 Cambridge University Press. In this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non-polar lipid layer, the thickness of the aqueous layer and the concentration of polar lipids which reside at the interface between the two. We also utilise a force balance in the non-polar lipid layer in order to determine its velocity. We show how to obtain previous models in the literature from our model by making particular choices of the parameters. We see the formation of boundary layers in some of these submodels, across which the concentration of polar lipid and the non-polar lipid velocity and film thickness vary. We solve our model numerically for physically realistic parameter values, and we find that the evolution of the aqueous layer and the polar lipid layer are similar to that described by previous authors. However, there are interesting dynamics for the non-polar lipid layer. The effects of altering the key parameters are highlighted and discussed. In particular, we see that the Marangoni number plays a key role in determining how far over the eye the non-polar lipid spreads.

  8. Mechanism of Nonpolar Model Substances to Inhibit Primary Gushing Induced by Hydrophobin HFBI.

    Science.gov (United States)

    Shokribousjein, Zahra; Riveros Galan, David; Losada-Pérez, Patricia; Wagner, Patrick; Lammertyn, Jeroen; Arghir, Iulia; Golreihan, Asefeh; Verachtert, Hubert; Aydın, Ahmet Alper; De Maeyer, Marc; Titze, Jean; Ilberg, Vladimír; Derdelinckx, Guy

    2015-05-13

    In this work, the interactions of a well-studied hydrophobin with different types of nonpolar model substances and their impact on primary gushing is evaluated. The nature, length, and degree of saturation of nonpolar molecules are key parameters defining the gushing ability or inhibition. When mixed with hydrophobins, the nonpolar molecule-hydrophobin assembly acts as a less gushing or no gushing system. This effect can be explained in the framework of a competition effect between non-polar systems and CO2 to interact with the hydrophobic patch of the hydrophobin. Interactions of these molecules with hydrophobins are promoted as a result of the similar size of the nonpolar molecules with the hydrophobic patch of the protein, at the expense of the formation of nanobubbles with CO2. In order to prove the presence of interactions and to unravel the mechanisms behind them, a complete set of experimental techniques was used. Surface sensitive techniques clearly show the presence of the interactions, whose nature is not covalent nor hydrogen bonding according to infrared spectroscopy results. Interactions were also reflected by particle size analysis in which mixtures of particles displayed larger size than their pure component counterparts. Upon mixing with nonpolar molecules, the gushing ability of the protein is significantly disrupted.

  9. Nigella sativa Infusion as an Antioxidant Agent Against Gentamicin-Induced Kidney Damaged in Mice

    Directory of Open Access Journals (Sweden)

    Hamsiah binti Halim

    2014-08-01

    Full Text Available Background: Gentamicin is one of the most common antibiotics related to nephrotoxicity. It has been proposed that the nephrotoxicity is associated with the generation of the reactive oxygen species. Thymoquinone, an active compound of Nigella sativa, shows to have an antioxidant property. The study aims to identify the possible nephroprotective action of Nigella sativa infusion against gentamicin-induced kidney damaged in mice. Methods:This experimental study was carried out in the Department of Cell Biology Laboratory, Universitas Padjadjaran, Bandung from 10th November 2012 to 14th December 2012. There were four groups, each consisting of 6 mice. Group I (control negative, group II (gentamicin 100 mg/kg, group III (3.9 mg Nigella sativa infusion+gentamicin 100mg/kg and group IV (7.8 mg Nigella sativa infusion+gentamicin 100mg/kg. The kidneys were evaluated histopathologically by light microscope. The percentage average number of normal proximal tubules in group I and the percentage average number of proximal tubules damaged in group II, III and IV were measured. Results: The results showed the percentage average number of the proximal tubules damaged in group II, III and IV were 14.53%, 7.49% and 3.94% respectively. Significant differences were observed between group II and III, group II and IV, and group III and IV. Conclusion:Nigella sativa infusion protects against gentamicin-induced kidney damage in mice.

  10. K88 Fimbrial Adhesin Targeting of Microspheres Containing Gentamicin Made with Albumin Glycated with Lactose

    Directory of Open Access Journals (Sweden)

    Andre-i Sarabia-Sainz

    2015-09-01

    Full Text Available The formulation and characterization of gentamicin-loaded microspheres as a delivery system targeting enterotoxigenic Escherichia coli K88 (E. coli K88 was investigated. Glycated albumin with lactose (BSA-glucose-β (4-1 galactose was used as the microsphere matrix (MS-Lac and gentamicin included as the transported antibiotic. The proposed target strategy was that exposed galactoses of MS-Lac could be specifically recognized by E. coli K88 adhesins, and the delivery of gentamicin would inhibit bacterial growth. Lactosylated microspheres (MS-Lac1, MS-Lac2 and MS-Lac3 were obtained using a water-in-oil emulsion, containing gentamicin, followed by crosslinking with different concentrations of glutaraldehyde. Electron microscopy displayed spherical particles with a mean size of 10–17 µm. In vitro release of gentamicin from MS-Lac was best fitted to a first order model, and the antibacterial activity of encapsulated and free gentamicin was comparable. MS-Lac treatments were recognized by plant galactose-specific lectins from Ricinus communis and Sophora japonica and by E. coli K88 adhesins. Results indicate MS-Lac1, produced with 4.2 mg/mL of crosslinker, as the best treatment and that lactosylated microsphere are promising platforms to obtain an active, targeted system against E. coli K88 infections.

  11. Persistence of gentamicin residues in milk after the intramammary treatment of lactating cows for mastitis

    Institute of Scientific and Technical Information of China (English)

    Xun TAN; Ye-wen JIANG; Yi-jun HUANG; Song-hua HU

    2009-01-01

    This study was designed to investigate persistence of gentamicin residues in milk after the intramammary treatment of lactating cows for mastitis. Milk samples were collected at a 1-d interval after the last administration from 34 individual cows that had received intramammary infusions of gentamicin. The doses and treatment times evaluated in this study represented those that have been applied by veterinarians in practice. The tetrazolium chloride assay was used to determine whether there were sig-nificant residues of the antibiotic in the samples. Persistence of detectable drug residues in milk from 33 cows (28 cows, <6 infusions at≤0.7 g gentamicin; and 5 cows, 2 infusions at 0.8 g gentamicin) did not exceed 5 d; but 1 cow (5 infusions at 0.8 g gentamicin) had detectable residues in its milk for 9 d. Our results suggest that a 5-d milk withdrawal period might be insufficient to secure the clearance of the contamination of gentamicin, because treatment times and dosages contribute to the antibiotic clearance. A larger scale of samples are needed for further investigations.

  12. K88 Fimbrial Adhesin Targeting of Microspheres Containing Gentamicin Made with Albumin Glycated with Lactose

    Science.gov (United States)

    Sarabia-Sainz, Andre-i; Sarabia-Sainz, Hector Manuel; Ramos-Clamont Montfort, Gabriela; Mata-Haro, Veronica; Guzman-Partida, Ana María; Guzman, Roberto; Garcia-Soto, Mariano; Vazquez-Moreno, Luz

    2015-01-01

    The formulation and characterization of gentamicin-loaded microspheres as a delivery system targeting enterotoxigenic Escherichia coli K88 (E. coli K88) was investigated. Glycated albumin with lactose (BSA-glucose-β (4-1) galactose) was used as the microsphere matrix (MS-Lac) and gentamicin included as the transported antibiotic. The proposed target strategy was that exposed galactoses of MS-Lac could be specifically recognized by E. coli K88 adhesins, and the delivery of gentamicin would inhibit bacterial growth. Lactosylated microspheres (MS-Lac1, MS-Lac2 and MS-Lac3) were obtained using a water-in-oil emulsion, containing gentamicin, followed by crosslinking with different concentrations of glutaraldehyde. Electron microscopy displayed spherical particles with a mean size of 10–17 µm. In vitro release of gentamicin from MS-Lac was best fitted to a first order model, and the antibacterial activity of encapsulated and free gentamicin was comparable. MS-Lac treatments were recognized by plant galactose-specific lectins from Ricinus communis and Sophora japonica and by E. coli K88 adhesins. Results indicate MS-Lac1, produced with 4.2 mg/mL of crosslinker, as the best treatment and that lactosylated microsphere are promising platforms to obtain an active, targeted system against E. coli K88 infections. PMID:26389896

  13. The Role of Monitoring Gentamicin Levels in Patients with Gram-Negative Peritoneal Dialysis-Associated Peritonitis

    Science.gov (United States)

    Tang, Wen; Cho, Yeoungjee; Hawley, Carmel M.; Badve, Sunil V.; Johnson, David W.

    2014-01-01

    ♦ Background: There is limited available evidence regarding the role of monitoring serum gentamicin concentrations in peritoneal dialysis (PD) patients receiving this antimicrobial agent in gram-negative PD-associated peritonitis. ♦ Methods: Using data collected in all patients receiving PD at a single center who experienced a gram-negative peritonitis episode between 1 January 2005 and 31 December 2011, we investigated the relationship between measured serum gentamicin levels on day 2 following initial empiric antibiotic therapy and subsequent clinical outcomes of confirmed gram-negative peritonitis. ♦ Results: Serum gentamicin levels were performed on day 2 in 51 (77%) of 66 first gram-negative peritonitis episodes. Average serum gentamicin levels on day 2 were 1.83 ± 0.84 mg/L with levels exceeding 2 mg/L in 22 (43%) cases. The overall cure rate was 64%. No cases of ototoxicity were observed. Day-2 gentamicin levels were not significantly different between patients who did and did not have a complication or cure. Using multivariable logistic regression analysis, failure to cure peritonitis was not associated with either day-2 gentamicin level (adjusted odds ratio (OR) 0.96, 95% confidence interval (CI) 0.25 - 3.73) or continuation of gentamicin therapy beyond day 2 (OR 0.28, 0.02 - 3.56). The only exception was polymicrobial peritonitis, where day-2 gentamicin levels were significantly higher in episodes that were cured (2.06 ± 0.41 vs 1.29 ± 0.71, p = 0.01). In 17 (26%) patients receiving extended gentamicin therapy, day-5 gentamicin levels were not significantly related to peritonitis cure. ♦ Conclusion: Day-2 gentamicin levels did not predict gentamicin-related harm or efficacy during short-course gentamicin therapy for gram-negative PD-related peritonitis, except in cases of polymicrobial peritonitis, where higher levels were associated with cure. PMID:24385334

  14. Gentamicin coated iron oxide nanoparticles as novel antibacterial agents

    Science.gov (United States)

    Bhattacharya, Proma; Neogi, Sudarsan

    2017-09-01

    Applications of different types of magnetic nanoparticles for biomedical purposes started a long time back. The concept of surface functionalization of the iron oxide nanoparticles with antibiotics is a novel technique which paves the path for further application of these nanoparticles by virtue of their property of superparamagnetism. In this paper, we have synthesized novel iron oxide nanoparticles surface functionalized with Gentamicin. The average size of the particles, concluded from the HR-TEM images, came to be around 14 nm and 10 nm for unmodified and modified nanoparticles, respectively. The magnetization curve M(H) obtained for these nanoparticles are typical of superparamagnetic nature and having almost zero values of coercivity and remanance. The release properties of the drug coated nanoparticles were studied; obtaining an S shaped profile, indicating the initial burst effect followed by gradual sustained release. In vitro investigations against various gram positive and gram negative strains viz Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis indicated significant antibacterial efficiency of the drug-nanoparticle conjugate. The MIC values indicated that a small amount like 0.2 mg ml‑1 of drug capped particles induce about 98% bacterial death. The novelty of the work lies in the drug capping of the nanoparticles, which retains the superparamagnetic nature of the iron oxide nanoparticles and the medical properties of the drug simultaneously, which is found to extremely blood compatible.

  15. Sulforaphane Attenuates Gentamicin-Induced Nephrotoxicity: Role of Mitochondrial Protection

    Science.gov (United States)

    Huerta-Yepez, Sara; Medina-Campos, Omar Noel; Zatarain-Barrón, Zyanya Lucía; Hernández-Pando, Rogelio; Torres, Ismael; Tapia, Edilia; Pedraza-Chaverri, José

    2013-01-01

    Sulforaphane (SFN), an isothiocyanate naturally occurring in Cruciferae, induces cytoprotection in several tissues. Its protective effect has been associated with its ability to induce cytoprotective enzymes through an Nrf2-dependent pathway. Gentamicin (GM) is a widely used antibiotic; nephrotoxicity is the main side effect of this compound. In this study, it was investigated if SFN is able to induce protection against GM-induced nephropathy both in renal epithelial LLC-PK1 cells in culture and in rats. SFN prevented GM-induced death and loss of mitochondrial membrane potential in LLC-PK1 cells. In addition, it attenuated GM-induced renal injury (proteinuria, increases in serum creatinine, in blood urea nitrogen, and in urinary excretion on N-acetyl-β-D-glucosaminidase, and decrease in creatinine clearance and in plasma glutathione peroxidase activity) and necrosis and apoptosis in rats. The apoptotic death was associated with enhanced active caspase-9. Caspase-8 was unchanged in all the studied groups. In addition, SFN was able to prevent GM-induced protein nitration and decrease in the activity of antioxidant enzymes catalase and glutathione peroxidase in renal cortex. In conclusion, the protective effect of SFN against GM-induced acute kidney injury could be associated with the preservation in mitochondrial function that would prevent the intrinsic apoptosis and nitrosative stress. PMID:23662110

  16. Sulforaphane Attenuates Gentamicin-Induced Nephrotoxicity: Role of Mitochondrial Protection

    Directory of Open Access Journals (Sweden)

    Mario Negrette-Guzmán

    2013-01-01

    Full Text Available Sulforaphane (SFN, an isothiocyanate naturally occurring in Cruciferae, induces cytoprotection in several tissues. Its protective effect has been associated with its ability to induce cytoprotective enzymes through an Nrf2-dependent pathway. Gentamicin (GM is a widely used antibiotic; nephrotoxicity is the main side effect of this compound. In this study, it was investigated if SFN is able to induce protection against GM-induced nephropathy both in renal epithelial LLC-PK1 cells in culture and in rats. SFN prevented GM-induced death and loss of mitochondrial membrane potential in LLC-PK1 cells. In addition, it attenuated GM-induced renal injury (proteinuria, increases in serum creatinine, in blood urea nitrogen, and in urinary excretion on N-acetyl-β-D-glucosaminidase, and decrease in creatinine clearance and in plasma glutathione peroxidase activity and necrosis and apoptosis in rats. The apoptotic death was associated with enhanced active caspase-9. Caspase-8 was unchanged in all the studied groups. In addition, SFN was able to prevent GM-induced protein nitration and decrease in the activity of antioxidant enzymes catalase and glutathione peroxidase in renal cortex. In conclusion, the protective effect of SFN against GM-induced acute kidney injury could be associated with the preservation in mitochondrial function that would prevent the intrinsic apoptosis and nitrosative stress.

  17. Activity of daptomycin or linezolid in combination with rifampin or gentamicin against biofilm-forming Enterococcus faecalis or E. faecium in an in vitro pharmacodynamic model using simulated endocardial vegetations and an in vivo survival assay using Galleria mellonella larvae.

    Science.gov (United States)

    Luther, Megan K; Arvanitis, Marios; Mylonakis, Eleftherios; LaPlante, Kerry L

    2014-08-01

    Enterococci are the third most frequent cause of infective endocarditis. A high-inoculum stationary-phase in vitro pharmacodynamic model with simulated endocardial vegetations was used to simulate the human pharmacokinetics of daptomycin at 6 or 10 mg/kg of body weight/day or linezolid at 600 mg every 12 h (q12h), alone or in combination with gentamicin at 1.3 mg/kg q12h or rifampin at 300 mg q8h or 900 mg q24h. Biofilm-forming, vancomycin-susceptible Enterococcus faecalis and vancomycin-resistant Enterococcus faecium (vancomycin-resistant enterococcus [VRE]) strains were tested. At 24, 48, and 72 h, all daptomycin-containing regimens demonstrated significantly more activity (decline in CFU/g) than any linezolid-containing regimen against biofilm-forming E. faecalis. The addition of gentamicin to daptomycin (at 6 or 10 mg/kg) in the first 24 h significantly improved bactericidal activity. In contrast, the addition of rifampin delayed the bactericidal activity of daptomycin against E. faecalis, and the addition of rifampin antagonized the activities of all regimens against VRE at 24 h. Also, against VRE, the addition of gentamicin to linezolid at 72 h improved activity and was bactericidal. Rifampin significantly antagonized the activity of linezolid against VRE at 72 h. In in vivo Galleria mellonella survival assays, linezolid and daptomycin improved survival. Daptomycin at 10 mg/kg improved survival significantly over that with linezolid against E. faecalis. The addition of gentamicin improved the efficacy of daptomycin against E. faecalis and those of linezolid and daptomycin against VRE. We conclude that in enterococcal infection models, daptomycin has more activity than linezolid alone. Against biofilm-forming E. faecalis, the addition of gentamicin in the first 24 h causes the most rapid decline in CFU/g. Of interest, the addition of rifampin decreased the activity of daptomycin against both E. faecalis and VRE.

  18. Deviations from sorption linearity on soils of polar and nonpolar organic compounds at low relative concentrations

    Science.gov (United States)

    Chiou, C.T.; Kile, D.E.

    1998-01-01

    A series of single-solute and binary-solute sorption data have been obtained on representative samples of polar compounds (substituted ureas and phenolic compounds) and of nonpolar compounds (e.g., EDB and TCE) on a peat soil and a mineral (Woodburn) soil; the data extend to low relative solute concentrations (C(e)/S(w)). At relatively low C(e)/S(w), both the nonpolar and the polar solutes exhibit nonlinear sorption. The sorption nonlinearity approaches apparent saturation at about C(e)/S(w) = 0.010-0.015 for the nonpolar solutes and at about C(e)/S(w) = 0.10-0.13 for the polar solutes; above these C(e)/S(w) regions, the isotherms are practically linear. The nonlinear sorption capacities are greater for polar solutes than for nonpolar solutes and the peat soil shows a greater effect than the Woodburn soil. The small nonlinear sorption capacity for a nonpolar solute is suppressed indiscriminately by either a nonpolar or a polar cosolute at relatively low C(e)/S(w) of the cosolute. By contrast, the abilities of different cosolutes to suppress the nonlinear capacity of a nominal polar solute differ drastically. For polar solutes, a nonpolar cosolute exhibits a limited suppression even at high cosolute C(e)/S(w); effective suppression occurs when the cosolute is relatively polar and at various C(e)/S(w). These differences suggest that more than a single mechanism is required to account for the nonlinear sorption of both nonpolar and polar compounds at low C(e)/S(w). Mechanistic processes consistent with these observations and with soil surface areas are discussed along with other suggested models. Some important consequences of the nonlinear competitive sorption to the behavior of contaminants in natural systems are discussed.A number of conceptual models was postulated to account for the nonlinear solute sorption on soils of significant soil organic matter. A series of single-solute and binary-route sorption data was obtained representing samples of polar compounds of

  19. Methods for recovering a solvent from a fluid volume and methods of removing at least one compound from a nonpolar solvent

    Energy Technology Data Exchange (ETDEWEB)

    Ginosar, Daniel M.; Wendt, Daniel S.; Petkovic, Lucia M.

    2014-06-10

    A method of removing a nonpolar solvent from a fluid volume that includes at least one nonpolar compound, such as a fat, an oil or a triglyceride, is provided. The method comprises contacting a fluid volume with an expanding gas to expand the nonpolar solvent and form a gas-expanded solvent. The gas-expanded solvent may have a substantially reduced density in comparison to the at least one nonpolar compound and/or a substantially reduced capacity to solubilize the nonpolar compound, causing the nonpolar compounds to separate from the gas-expanded nonpolar solvent into a separate liquid phase. The liquid phase including the at least one nonpolar compound may be separated from the gas-expanded solvent using conventional techniques. After separation of the liquid phase, at least one of the temperature and pressure may be reduced to separate the nonpolar solvent from the expanding gas such that the nonpolar solvent may be recovered and reused.

  20. Therapeutic efficacy of liposome-encapsulated gentamicin in rat Klebsiella pneumoniae pneumonia in relation to impaired host defense and low bacterial susceptibility to gentamicin.

    NARCIS (Netherlands)

    R.M. Schiffelers (Raymond); G. Storm (Gert); M.T. ten Kate (Marian); I.A.J.M. Bakker-Woudenberg (Irma)

    2001-01-01

    textabstractLong-circulating liposomes (LCL) may be used as targeted antimicrobial drug carriers as they localize at sites of infection. As a result, LCL-encapsulated gentamicin (LE-GEN) has demonstrated superior antibacterial activity over the free drug in a single-dos

  1. Activity of daptomycin alone and in combination with rifampin and gentamicin against Staphylococcus aureus assessed by time-kill methodology.

    Science.gov (United States)

    Credito, Kim; Lin, Gengrong; Appelbaum, Peter C

    2007-04-01

    The synergistic effects of daptomycin plus gentamicin or rifampin were tested against 50 Staphylococcus aureus strains, with daptomycin MICs ranging between 0.25 and 8 microg/ml. Daptomycin sub-MICs combined with gentamicin concentrations lower than the MIC yielded synergy in 34 (68%) of the 50 strains. Daptomycin combined with rifampin yielded synergy in one vancomycin-intermediate S. aureus strain only, and virtually all synergy occurred between daptomycin and gentamicin.

  2. Protective effect of quercetin against gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    Abdel-Raheem, Ihab Talat; Abdel-Ghany, Ahmed Ali; Mohamed, Gamal Abdallah

    2009-01-01

    Gentamicin (GM) is an antibiotic widely used in treating severe gram-negative infections. However, its clinical use is limited by its nephrotoxicity. Several lines of evidence indicate that free radicals are important mediators of gentamicin nephrotoxicity. Therefore, the aim of this work was to investigate the possible protective effect of the flavonoid quercetin, an antioxidant, on gentamicin-induced nephrotoxicity. For this purpose, rats were divided into four groups. First group served as a control and injected with the normal saline, second group was injected with quercetin (50 mg/kg/d, per os) for 7 d, third group was injected with gentamicin (80 mg/kg/d, intraperitoneally) for 7 d and the fourth group of animals was injected with quercetin plus gentamicin simultaneously for 7 d. Total protein levels were estimated in 24-h urine samples to assess kidney dysfunction. The rats were sacrificed on the seventh day and kidneys were collected for histopathological studies. Blood urea nitrogen (BUN) and creatinine levels were measured in the blood. Moreover, glutathione (GSH), lipid peroxide (TBARS) levels, superoxide dismutase (SOD) and catalase (CAT) activities were determined in renal tissues. GM-treated rats showed early kidney dysfunction as urinary total protein, BUN and serum creatinine levels were significantly increased. The significant decrease in GSH levels, SOD, CAT activities and increase in TBARS levels, indicated that GM-induced nephrotoxicity was mediated through oxidative stress reactions. Histopathological examination of GM-treated rats revealed degenerative changes in glomeruli and tubules. On the other hand, simultaneous administration of quercetin plus gentamicin protected kidney tissues against nephrotoxic effects of gentamicin as evidenced from amelioration of histopathological changes and normalization of kidney biochemical parameters.

  3. In vitro release and antibacterial activity of poly(oleic/linoleic acid dimer:sebacic acid)-gentamicin

    Institute of Scientific and Technical Information of China (English)

    YANGXiu-Fen; ZHOUZhi-Bin; 等

    2003-01-01

    AIM:To investigate whether poly(oleic/linoleic acid dimer:sebacic acid)-getamicin[Poly(OAD/LOAD:SA)-gentamicin]delivery system was useful to treat chronic osteomyelitis.METHODS:Drug delivery system consisted of gentamicin sufate dispersed in a copolymer containing oleic/linoleic acid dimer(OAD/LOAD)and sebacic acid(SA)in a 1:1 weight ration.The gentamicin releast from[Poly(OAD/LOAD:SA)-gentamicin]was tested in water 0.9% saline,and phosphate buffer 0.1mol/L,RESULTS:The gentamicin concentration peak was found on d2,then slowly decreased.considerable amout of gentamicin was still released on d 50.From d 2 o d 50,the gentamicin concentration in the releasing fluids was from 59 to 42128-fold and 1.8 to 1314-fold of the MIC for Staphylococcus aureus and Escherichia coli,respectively.Staphylococcus aureus and Escherichia coli were strongly inhibited by the releasing fluids for 50d.The gentamicin release and anti-bacterial activity in the three media were similar.only in 0.1mol/L phosphate buffer,from d 2 to 14 it was lower.CONCLUSION:Poly(OAD/LOAD:SA)-gentamicin was useful to treat chronic osteomyelitis.

  4. Simulation of Nonpolar p-GaN/i-N/n-GaN Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Jer Jeng

    2012-01-01

    Full Text Available It is well known that nitride-based devices suffer the polarization effects. A promising way to overcome the polarization effects is growth in a direction perpendicular to the c-axis (nonpolar direction. Nonpolar devices do not suffer polarization charge, and then they have a chance to achieve the high solar efficiency. The understanding of the solar performance of non-polar InGaN-based solar cells will be interesting. For a pin non-polar solar cell with GaN p- and n-cladding layers, the conduction band offset (or barrier height, between an intrinsic layer and n-GaN layer is an important issue correlating to the efficiency and fill factor. The efficiency and fill factor will be seriously degraded due to sufficiently high barrier height. To reduce a high barrier height, some graded layers with an energy bandgap between the energy bandgap of n-GaN and InxGa1−xN intrinsic layer can be inserted to the interface of n-GaN and InxGa1-xN layers. From simulation, it indicates that the insertion of graded layer is an effective method to lower energy barrier when there exists a high energy band offset in non-polar nitride devices.

  5. Large organized surface domains self-assembled from nonpolar amphiphiles.

    Science.gov (United States)

    Krafft, Marie Pierre

    2012-04-17

    unambiguously demonstrated the presence of surface micelles in monolayers of diblocks prior to LB transfer for atomic force microscopy imaging. We characterized an almost perfect two-dimensional crystal, with 12 assignable diffraction peaks, which established that self-assembly and regular nanopatterning were not caused by transfer or induced by the solid support. These experiments also provide the first direct identification of surface micelles on water, and the first identification of such large-size domains using GISAXS. Revisiting Langmuir film compression behavior after we realized that it actually was a compression of nanometric objects led to further unanticipated observations. These films could be compressed far beyond the documented film "collapse", eventually leading to the buildup of two superimposed, less-organized bilayers of diblocks on top of the initially formed monolayer of hemimicelles. Remarkably, the latter withstood the final, irreversible collapse of the composite films. "Gemini" tetrablocks, di(FnHm), with two Fn-chains and two Hm-chains, provided two superposed layers of discrete micelles, apparently the first example of thin films made of stacked discrete self-assembled nanoobjects. Decoration of solid surfaces with domains of predetermined size of these small "nonpolar" molecules is straightforward. Initial examples of applications include deposition of metal dots and catalytic oxidation of CO, and nanopatterning of SiO(2) films.

  6. Teicoplanin plus ciprofloxacin versus gentamicin plus piperacillin in the treatment of febrile neutropenic patients.

    Science.gov (United States)

    Kelsey, S M; Weinhardt, B; Collins, P W; Newland, A C

    1992-06-01

    Teicoplanin plus ciprofloxacin was compared with gentamicin plus piperacillin for the empirical treatment of fever in 80 neutropenic patients. A favourable response was seen in 78% of patients receiving teicoplanin plus ciprofloxacin and in 49% receiving gentamicin plus piperacillin (p less than 0.05). When microbiologically documented episodes were analysed separately, the response to teicoplanin plus ciprofloxacin was favourable in 81% of patients whereas only 35% responded favourably to gentamicin plus piperacillin (p = 0.034). Gram-positive organisms accounted for 76% of bacterial isolates, Staphylococcus epidermidis being the most common pathogen. Ten of 12 (83%) Staphylococcus epidermidis infections resolved when treated with teicoplanin plus ciprofloxacin as compared with 2 of 8 (25%) treated with gentamicin plus piperacillin. Teicoplanin is at least as effective as gentamicin plus piperacillin in the empirical treatment of febrile neutropenic patients and may be more effective in situations where gram-positive organisms are prevalent. The high incidence of gram-positive infections in our unit justifies the use of an agent with specific activity against gram-positive organisms in the first-line antibiotic regimen.

  7. Optimising intraperitoneal gentamicin dosing in peritoneal dialysis patients with peritonitis (GIPD study

    Directory of Open Access Journals (Sweden)

    Lipman Jeffrey

    2009-12-01

    Full Text Available Abstract Background Antibiotics are preferentially delivered via the peritoneal route to treat peritonitis, a major complication of peritoneal dialysis (PD, so that maximal concentrations are delivered at the site of infection. However, drugs administered intraperitoneally can be absorbed into the systemic circulation. Drugs excreted by the kidneys accumulate in PD patients, increasing the risk of toxicity. The aim of this study is to examine a model of gentamicin pharmacokinetics and to develop an intraperitoneal drug dosing regime that maximises bacterial killing and minimises toxicity. Methods/Design This is an observational pharmacokinetic study of consecutive PD patients presenting to the Royal Brisbane and Women's Hospital with PD peritonitis and who meet the inclusion criteria. Participants will be allocated to either group 1, if anuric as defined by urine output less than 100 ml/day, or group 2: if non-anuric, as defined by urine output more than 100 ml/day. Recruitment will be limited to 15 participants in each group. Gentamicin dosing will be based on the present Royal Brisbane & Women's Hospital guidelines, which reflect the current International Society for Peritoneal Dialysis Peritonitis Treatment Recommendations. The primary endpoint is to describe the pharmacokinetics of gentamicin administered intraperitoneally in PD patients with peritonitis based on serial blood and dialysate drug levels. Discussion The study will develop improved dosing recommendations for intraperitoneally administered gentamicin in PD patients with peritonitis. This will guide clinicians and pharmacists in selecting the most appropriate dosing regime of intraperitoneal gentamicin to treat peritonitis. Trial Registration ACTRN12609000446268

  8. Grape seed extract prevents gentamicin-induced nephrotoxicity and genotoxicity in bone marrow cells of mice.

    Science.gov (United States)

    El-Ashmawy, Ibrahim M; El-Nahas, Abeer F; Salama, Osama M

    2006-09-01

    The protection conferred by grape seed extract against gentamicin-induced nephrotoxicity and bone marrow chromosomal aberrations have been evaluated in adult Swiss albino mice. The activity of reduced glutathione peroxidase (GSH peroxidase), the levels of glutathione (GSH) and lipid peroxidation as malondialdehyde (MDA) in the kidneys homogenates, serum urea and creatinine were measured, and in addition the changes in kidney histology and bone marrow chromosomes were investigated. Gentamicin (80 mg/kg b.wt. intraperitoneally for 2 weeks) induced kidney damage as indicated from a pronounced changes in kidney histology, a significant increase in serum urea and creatinine and MDA content in the kidney homogenate. While the activity of the antioxidant enzyme GSH peroxidase and the level of GSH were significantly decreased. Gentamicin induced genotoxicity indicated by increased the number of aberrant cells and different types of structural chromosomal aberrations (fragment, deletion and ring chromosome) and showed no effect on mitotic activity of the cell. Pretreatment with grape seed extract (7 days) and simultaneously (14 days) with gentamicin significantly protected the kidney tissue by ameliorating its antioxidant activity. Moreover, grape seed extract significantly protected bone marrow chromosomes from gentamicin induced genotoxicity by reducing the total number of aberrant cells, and different types of structural chromosomal aberrations. It could be concluded that grape seed extract acts as a potent antioxidant prevented kidney damage and genotoxicity of bone marrow cells.

  9. Passive Sampling in Regulatory Chemical Monitoring of Nonpolar Organic Compounds in the Aquatic Environment

    DEFF Research Database (Denmark)

    Booij, Kees; Robinson, Craig D; Burgess, Robert M;

    2016-01-01

    We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths and shor...... is the best available technology for chemical monitoring of nonpolar organic compounds. Key issues to be addressed by scientists and environmental managers are outlined.......We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths...... and shortcomings of passive sampling are assessed for water, sediments, and biota. Passive water sampling is a suitable technique for measuring concentrations of freely dissolved compounds. This method yields results that are incompatible with the EU's quality standard definition in terms of total concentrations...

  10. Chitosan Prevents Gentamicin-Induced Nephrotoxicity via a Carbonyl Stress-Dependent Pathway

    Directory of Open Access Journals (Sweden)

    Chu-Kung Chou

    2015-01-01

    Full Text Available Aminoglycosides are widely used to treat infections; however, their applications are limited by nephrotoxicity. With the increase of antibiotic resistance, the use of aminoglycosides is inevitable. Low-molecular-weight chitosan (LMWC has shown renal protective effects in dialysis patients. However, no study has evaluated LMWC for preventing aminoglycoside-induced nephrotoxicity or determined the mechanisms underlying the renal protective effects. In this study, LMWC (165 or 825 mg/kg/day or metformin (100 mg/kg/day was orally administered for 13 days to rats with nephropathy induced by gentamicin (GM, a kind of aminoglycoside (150 mg/kg/day i.p. for 6 days. Both LMCW doses improved renal function. Serum creatinine levels improved in rats treated with 165 and 825 mg/kg/day LMWC (from 2.14 ± 0.74 mg/dL to 1.26 ± 0.46 mg/dL and 0.69 ± 0.12 mg/dL, resp., P < 0.05. Blood urea nitrogen levels were also improved in these rats (from 73.73 ± 21.13 mg/dL to 58.70 ± 22.71 mg/dL and 28.82 ± 3.84 mg/dL, resp., P < 0.05. Additionally, renal tissue morphology improved after LMWC treatment, and accumulation of renal methylglyoxal, a damage factor associated with carbonyl stress, was reversed. These results show that LMWC prevents GM-induced renal toxicity via a carbonyl stress-dependent pathway.

  11. Nonpolar a-plane light-emitting diode with an in-situ SiNx interlayer on r-plane sapphire grown by metal-organic chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Fang Hao; Long Hao; Sang Li-Wen; Qi Sheng-Li; Xiong Chang; Yu Tong-Jun; Yang Zhi-Jian; Zhang Guo-Yi

    2011-01-01

    We report on the growth and fabrication of nonpolar a-plane light emitting diodes with an in-situ SiNx interlayer grown between the undoped a-plane GaN buffer and Si-doped GaN layer. X-ray diffraction shows that the crystalline quality of the GaN buffer layer is greatly improved with the introduction of the SiNx interlayer. The electrical properties are also improved. For example, electron mobility and sheet resistance are reduced from high resistance to 31.6 cm2/(V·s) and 460 Ω/□ respectively. Owing to the significant effect of the SiNx interlayer, a-plane LEDs are realized. Electroluminescence of a nonpolar a-plane light-emitting diode with a wavelength of 488nm is demonstrated.The emission peak remains constant when the injection current increases to over 20 mA.

  12. Gentamicin binds to the megalin receptor as a competitive inhibitor using the common ligand binding motif of complement type repeats: insight from the nmr structure of the 10th complement type repeat domain alone and in complex with gentamicin

    NARCIS (Netherlands)

    Dagil, R.; O'Shea, C.; Nykjaer, A.; Bonvin, A.M.J.J.; Kragelund, B.B.

    2013-01-01

    Gentamicin is an aminoglycoside widely used in treatments of, in particular, enterococcal, mycobacterial, and severe Gram-negative bacterial infections. Large doses of gentamicin cause nephrotoxicity and ototoxicity, entering the cell via the receptor megalin. Until now, no structural information ha

  13. Investigation of the Phase Equilibria and Interfacial Properties for Non-polar Fluids

    Institute of Scientific and Technical Information of China (English)

    付东; 赵毅

    2005-01-01

    A self-consistent density-functional theory (DFT) was applied to investigate the phase behavior and interfacial properties of non-polar fluids. For the bulk phases, the theory was reduced to the statistical associating fluid theory(SAFF) that provides accurate descriptions of vapor-liquid phase diagrams below the critical region. The phase diagrams in the critical region were corrected by the renormalization group theory (RGT). The density profile in the surface was obtained by minimizing the grand potential. With the same set of molecular parameters, both the phase equilibria and the interfacial properties of non-polar fluids were investigated satisfactorily.

  14. The development of an injection-molding process for a polyanhydride implant containing gentamicin sulfate.

    Science.gov (United States)

    Deng, Jone-Shin; Meisters, Marts; Li, Luk; Setesak, Jeff; Claycomb, Lee; Tian, Youqin; Stephens, Dennis; Widman, Matt

    2002-01-01

    A production-scale manufacturing process has been developed for polyanhydride/gentamicin sulfate implants for the treatment of osteomyelitis. Gentamicin sulfate was first dried to an acceptable moisture level by using a tumble vacuum dryer. Dried gentamicin sulfate powder and polyanhydride granules were separately fed into the twin-screw extruder at a pre-determined metering rate using a gravimetric feeding device. The extruded molten mixture was solidified to form strands which were subsequently cut into pellets by using a pelletizer. The pellets were characterized with respect to copolymer molecular weight and drug content uniformity. The pellets were later fed into production-scale injection-molding equipment for implant fabrication. The injection-molding cycle was developed and evaluated in terms of cycle reproducibility. Implants were tested and shown to yield an oriented skin-core structure exhibiting a desirable in-vitro drug release profile.

  15. Development of a Multicommutated Flow System with Chemiluminometric Detection for Quantification of Gentamicin in Pharmaceuticals

    Science.gov (United States)

    Santos, Lúcia H. M. L. M.; Araújo, A. N.; Reis, Boaventura; Montenegro, M. C. B. S. M.

    2010-01-01

    A new flow procedure based on multicommutation with chemiluminometric detection was developed to quantify gentamicin sulphate in pharmaceutical formulations. This approach is based on gentamicin's ability to inhibit the chemiluminometric reaction between luminol and hypochlorite in alkaline medium, causing a decrease in the analytical signal. The inhibition of the analytical signal is proportional to the concentration of gentamicin sulphate, within a linear range of 1 to 4 μg mL−1 with a coefficient variation <3%. A sample throughput of 55 samples h−1 was obtained. The developed method is sensitive, simple, with low reagent consumption, reproducible, and inexpensive, and when applied to the analysis of pharmaceutical formulations (eye drops and injections) it gave results with RSD between 1.10 and 4.40%. PMID:20981343

  16. Gentamicin tissue concentration in various avian species following recommended dosage therapy

    Science.gov (United States)

    Bush, M.; Locke, D.; Neal, L.A.; Carpenter, J.W.

    1981-01-01

    Plasma and tissue drug concentrations were compared in eastern bobwhite quail (Colinus virginianus virginianus) and pigeons (Columba livia) given gentamicin by IM administration at the dosage of 10 mg/kg, and in greater sandhill cranes (Grus canadensis tabida) and hybrid rosybill ducks (Netta sp) given the same antibiotic at a dosage of 5 mg/kg. Quail and cranes had significantly higher liver concentrations of gentamicin at 6 hours after injection than did pigeons and ducks. Cranes had significantly higher plasma concentrations than did ducks at 6 hours after injection. Compared with plasma values, gentamicin concentrations were significantly higher in the liver of cranes at 12 hours after injection, and in the kidneys at 18 hours.

  17. Toxic Anterior Segment Syndrome following Phacoemulsification Secondary to Overdose of Intracameral Gentamicin

    Directory of Open Access Journals (Sweden)

    Yaran Koban

    2014-01-01

    Full Text Available Objective. To report a case of toxic anterior segment syndrome (TASS that was caused by inadvertent anterior chamber and cornea stromal injection with high dose gentamicin following cataract surgery. Methods. Case report. Results. We report a 72-year-old female patient who developed TASS that was caused by high dose gentamicin (20 mg/0.5 mL, which was inadvertently used during the formation of the anterior chamber and hydration of the corneal incision. Unlike previous cases, hyphema and hemorrhagic fibrinous reaction were seen in the anterior chamber. Despite treatment, bullous keratopathy developed and penetrating keratoplasty was performed. The excised corneal button was sent for histopathological examination. Conclusions. Subconjunctival gentamicin is highly toxic to the corneal endothelium and anterior chamber structures. Including it on the surgical table carries a potentially serious risk for contamination of the anterior chamber.

  18. Toxic Anterior Segment Syndrome following Phacoemulsification Secondary to Overdose of Intracameral Gentamicin

    Science.gov (United States)

    Koban, Yaran; Genc, Selim; Cagatay, Halil Huseyin; Ekinci, Metin; Gecer, Melin; Yazar, Zeliha

    2014-01-01

    Objective. To report a case of toxic anterior segment syndrome (TASS) that was caused by inadvertent anterior chamber and cornea stromal injection with high dose gentamicin following cataract surgery. Methods. Case report. Results. We report a 72-year-old female patient who developed TASS that was caused by high dose gentamicin (20 mg/0.5 mL), which was inadvertently used during the formation of the anterior chamber and hydration of the corneal incision. Unlike previous cases, hyphema and hemorrhagic fibrinous reaction were seen in the anterior chamber. Despite treatment, bullous keratopathy developed and penetrating keratoplasty was performed. The excised corneal button was sent for histopathological examination. Conclusions. Subconjunctival gentamicin is highly toxic to the corneal endothelium and anterior chamber structures. Including it on the surgical table carries a potentially serious risk for contamination of the anterior chamber. PMID:25574173

  19. Production of biocompatible and antimicrobial bacterial cellulose polymers functionalized by RGDC grafting groups and gentamicin.

    Science.gov (United States)

    Rouabhia, Mahmoud; Asselin, Jérémie; Tazi, Neftaha; Messaddeq, Younès; Levinson, Dennis; Zhang, Ze

    2014-02-12

    Bacterial cellulose (BC), a three-dimensional fibril, is a natural polymer that can be used for many applications. BC effectiveness may be improved by enhancing surface characteristics contributing to a better physiologic interaction with human and animal cells and to intrinsically present antimicrobial agents. In the present study, gentamicin-activated BC membranes were obtained by chemically grafting RGDC peptides (R: arginine; G: glycine; D: aspartic acid; C: cysteine) using coupling agent 3-aminopropyltriethoxysilane (APTES) followed by covalent attachment of gentamicin onto the surface of the BC membrane network. X-ray photoelectron spectroscopy (XPS) analyses showed that the BC-APTES contained 0.7% of silicon in terms of elemental composition, corresponding to a grafting ratio of 1:12. The presence of silicon and nitrogen in the BC-APTES confirmed the surface functionalization of the BC membrane. Fourier-transform infrared (FTIR) analyses show the formation of the secondary amide as supported by the valence bond C═O (ν(C═O)), a characteristic vibrational transition at 1650 cm(-1) which is particularly intense with the BC-RGDC-gentamicin membrane. Energy-dispersive X-ray (EDX) analyses showed a low level of carbon and nitrogen (C + N) in pure BC but a high level of (C + N) in BC-RGDC-gentamicin confirming the surface modification of the BC membrane by RGDC and gentamicin enrichment. Of great interest, the gentamicin-RGDC-grafted BC membranes are bactericidal against Streptococcus mutans but nontoxic to human dermal fibroblasts and thus may be useful for multiple applications such as improved wound healing and drug delivery systems.

  20. Efficacies of gentamicin-loaded magnetite block ionomer complexes against chronic Brucella melitensis infection

    Science.gov (United States)

    Jain-Gupta, Neeta; Pothayee, Nipon; Pothayee, Nikorn; Tyler, Ronald; Caudell, David L.; Balasubramaniam, Sharavanan; Hu, Nan; Davis, Richey M.; Riffle, Judy S.; Sriranganathan, Nammalwar

    2013-11-01

    Anionic copolymers can enable intracellular delivery of cationic drugs which otherwise cannot cross cell membrane barriers. We tested the efficacy of gentamicin-loaded magnetite block ionomer complexes (MBICs) against intracellular Brucella melitensis. Anionic block copolymers were used to coat nanomagnetite through adsorption of a portion of anions on the particle surfaces, then the remaining anions were complexed with 30-32 weight percentage of gentamicin. The zeta potential changed from -39 to -13 mV after encapsulation of the drug with complementary charge. The gentamicin-loaded MBICs had intensity average hydrodynamic diameters of 62 nm, while the polymer-coated nanomagnetite particles without drug were 34 nm in size. No toxicity as measured by a MTS assay was observed upon incubation of the MBICs with J774A.1 murine macrophage-like cells. Confocal microscopic images showed that the MBICs were taken up by the macrophages and distributed in the cell cytoplasm and endosomal/lysosomal compartments. Upon treatment with gentamicin-loaded MBICs (3.5 Log10), B. melitensis-infected macrophages showed significantly higher clearance of Brucella compared to the treatment with free g (0.9 Log10). Compared to doxycycline alone, a combination of doxycycline and gentamicin (either free or encapsulated in MBICs) showed significantly higher clearance of B. melitensis from chronically infected mice. Histopathological examination of kidneys from the MBICs-treated mice revealed multifocal infiltration of macrophages containing intracytoplasmic iron (MBICs) in peri-renal adipose. Although MBICs showed similar efficacy as free gentamicin against Brucella in mice, our strategy presents an effective way to deliver higher loads of drugs intracellularly and ability to study the bio-distribution of drug carriers.

  1. Efficacies of gentamicin-loaded magnetite block ionomer complexes against chronic Brucella melitensis infection

    Energy Technology Data Exchange (ETDEWEB)

    Jain-Gupta, Neeta [Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Department of Biomedical Sciences and Pathobiology (United States); Pothayee, Nipon; Pothayee, Nikorn [Virginia Polytechnic Institute and State University, Macromolecules and Interfaces Institute (United States); Tyler, Ronald; Caudell, David L. [Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Department of Biomedical Sciences and Pathobiology (United States); Balasubramaniam, Sharavanan; Hu, Nan; Davis, Richey M.; Riffle, Judy S. [Virginia Polytechnic Institute and State University, Macromolecules and Interfaces Institute (United States); Sriranganathan, Nammalwar, E-mail: nathans@vt.edu [Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Department of Biomedical Sciences and Pathobiology (United States)

    2013-11-15

    Anionic copolymers can enable intracellular delivery of cationic drugs which otherwise cannot cross cell membrane barriers. We tested the efficacy of gentamicin-loaded magnetite block ionomer complexes (MBICs) against intracellular Brucella melitensis. Anionic block copolymers were used to coat nanomagnetite through adsorption of a portion of anions on the particle surfaces, then the remaining anions were complexed with 30–32 weight percentage of gentamicin. The zeta potential changed from −39 to −13 mV after encapsulation of the drug with complementary charge. The gentamicin-loaded MBICs had intensity average hydrodynamic diameters of 62 nm, while the polymer-coated nanomagnetite particles without drug were 34 nm in size. No toxicity as measured by a MTS assay was observed upon incubation of the MBICs with J774A.1 murine macrophage-like cells. Confocal microscopic images showed that the MBICs were taken up by the macrophages and distributed in the cell cytoplasm and endosomal/lysosomal compartments. Upon treatment with gentamicin-loaded MBICs (3.5 Log{sub 10}), B. melitensis-infected macrophages showed significantly higher clearance of Brucella compared to the treatment with free g (0.9 Log{sub 10}). Compared to doxycycline alone, a combination of doxycycline and gentamicin (either free or encapsulated in MBICs) showed significantly higher clearance of B.melitensis from chronically infected mice. Histopathological examination of kidneys from the MBICs-treated mice revealed multifocal infiltration of macrophages containing intracytoplasmic iron (MBICs) in peri-renal adipose. Although MBICs showed similar efficacy as free gentamicin against Brucella in mice, our strategy presents an effective way to deliver higher loads of drugs intracellularly and ability to study the bio-distribution of drug carriers.

  2. Listeria monocytogenes Strains Selected on Ciprofloxacin or the Disinfectant Benzalkonium Chloride Exhibit Reduced Susceptibility to Ciprofloxacin, Gentamicin, Benzalkonium Chloride, and Other Toxic Compounds▿

    Science.gov (United States)

    Rakic-Martinez, Mira; Drevets, Douglas A.; Dutta, Vikrant; Katic, Vera; Kathariou, Sophia

    2011-01-01

    Listeria monocytogenes is a leading agent for severe food-borne illness and death in the United States and other nations. Even though drug resistance has not yet threatened therapeutic interventions for listeriosis, selective pressure associated with exposure to antibiotics and disinfectants may result in reduced susceptibility to these agents. In this study, selection of several L. monocytogenes strains on either ciprofloxacin (2 μg/ml) or the quaternary ammonium disinfectant benzalkonium chloride (BC; 10 μg/ml) led to derivatives with increased MICs not only to these agents but also to several other toxic compounds, including gentamicin, the dye ethidium bromide, and the chemotherapeutic drug tetraphenylphosphonium chloride. The spectrum of compounds to which these derivatives exhibited reduced susceptibility was the same regardless of whether they were selected on ciprofloxacin or on BC. Inclusion of strains harboring the large plasmid pLM80 revealed that MICs to ciprofloxacin and gentamicin did not differ between the parental and plasmid-cured strains. However, ciprofloxacin-selected derivatives of pLM80-harboring strains had higher MICs than those derived from the plasmid-cured strains. Susceptibility to the antimicrobials was partially restored in the presence of the potent efflux inhibitor reserpine. Taken together, these data suggest that mutations in efflux systems are responsible for the multidrug resistance phenotype of strains selected on ciprofloxacin or BC. PMID:22003016

  3. Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats.

    Science.gov (United States)

    Diefenbeck, M; Schrader, C; Gras, F; Mückley, T; Schmidt, J; Zankovych, S; Bossert, J; Jandt, K D; Völpel, A; Sigusch, B W; Schubert, H; Bischoff, S; Pfister, W; Edel, B; Faucon, M; Finger, U

    2016-09-01

    Implant related infection is one of the most feared and devastating complication associated with the use of orthopaedic implant devices. Development of anti-infective surfaces is the main strategy to prevent implant contamination, biofilm formation and implant related osteomyelitis. A second concern in orthopaedics is insufficient osseointegration of uncemented implant devices. Recently, we reported on a macroporous titanium-oxide surface (bioactive TiOB) which increases osseointegration and implant fixation. To combine enhanced osseointegration and antibacterial function, the TiOB surfaces were, in addition, modified with a gentamicin coating. A rat osteomyelitis model with bilateral placement of titanium alloy implants was employed to analyse the prophylactic effect of gentamicin-sodiumdodecylsulfate (SDS) and gentamicin-tannic acid coatings in vivo. 20 rats were randomly assigned to four groups: (A) titanium alloy; PBS inoculum (negative control), (B) titanium alloy, Staphylococcus aureus inoculum (positive control), (C) bioactive TiOB with gentamicin-SDS and (D) bioactive TiOB plus gentamicin-tannic acid coating. Contamination of implants, bacterial load of bone powder and radiographic as well as histological signs of implant-related osteomyelitis were evaluated after four weeks. Gentamicin-SDS coating prevented implant contamination in 10 of 10 tibiae and gentamicin-tannic acid coating in 9 of 10 tibiae (infection prophylaxis rate 100% and 90% of cases, respectively). In Group (D) one implant showed colonisation of bacteria (swab of entry point and roll-out test positive for S. aureus). The interobserver reliability showed no difference in the histologic and radiographic osteomyelitis scores. In both gentamicin coated groups, a significant reduction of the histological osteomyelitis score (geometric mean values: C = 0.111 ± 0.023; D = 0.056 ± 0.006) compared to the positive control group (B: 0.244 ± 0.015; p < 0.05) was observed. The

  4. Floral extract ofTecoma stans:A potent inhibitor of gentamicin-induced nephrotoxicityin vivo

    Institute of Scientific and Technical Information of China (English)

    Raju S; Kavimani S; Uma Maheshwara rao V; Sreeramulu Reddy K; Vasanth Kumar G

    2011-01-01

    Objective:To highlight the nephroprotective activity of ethyl acetate extract of dried flowers ofTecoma stans for its protective effects on gentamicin-induced nephrotoxicity in albino rats. Methods:For studying acute toxicity study, single oral dose of5 000 mg ethyl acetate floral extract/kg body weight was administered to albino rats (five females, five males). Nephrotoxicity was induced in albino rats by intraperitoneal administration of gentamicin80 mg/kg/day for eight days. Effect of concurrent administration of ethyl acetate floral extract of Tecoma stans at a dose of 100, 200 and 300 mg/kg/day given by oral route was determined using serumcreatinine, serum uric acid, blood urea nitrogen and serum urea as indicators of kidney damage. The study groups contained six rats in each group. As nephrotoxicity of gentamicin is known to involve induction of oxidative stress,in vitro antioxidant activity and free radical-scavenging activity of this extract was also evaluated.Results:For acute toxicity testing both female and male rats administered with the extract at a dose of5 000mg/kg. The results showed no toxicity in terms of general behavior change, mortality, or change in gross appearance of internal organs (LD50 > 5 000 mg/kg). It was observed that the ethyl acetate floral extract ofTecoma stans significantly protected rat kidneys from gentamicin-induced histopathological changes. Gentamicin-induced glomerular congestion, peritubular and blood vessel congestion, epithelial desquamation, accumulation of inflammatory cells and necrosis of the kidney cells were found to be reduced in the groups receiving the ethyl acetate floral extract ofTecoma stans along with gentamicin in a dose dependent manner. The floral extract also reduced the gentamicin-induced increase in serum creatinine, serum uric acid, blood urea nitrogen and serum urea levels (P>0.01).Conclusions:The present study indicates a very important role of reactive oxygen species (ROS)and the relation to

  5. Auditory function after continuous infusion of gentamicin to high-risk newborns

    DEFF Research Database (Denmark)

    Colding, H; Andersen, E A; Prytz, S;

    1989-01-01

    Audiometry was performed at four years of age in 69 of 105 surviving children who had received continuous intravenous infusion of gentamicin during neonatal intensive care. A hearing loss of 20 dB was found in 2 of them (3%), corresponding to that shown in other studies of survivors following...... neonatal intensive care. Free field audiometry performed in another 7 children and questionnaires returned from 13 of the remaining 29 gave no suspicion of hearing loss. Thus there is no indication that continuous 24 hours intravenous infusion of gentamicin causes more hearing impairment than intermittent...

  6. Effect of sepsis and systemic inflammatory response syndrome on neonatal hearing screening outcomes following gentamicin exposure.

    Science.gov (United States)

    Cross, Campbell P; Liao, Selena; Urdang, Zachary D; Srikanth, Priya; Garinis, Angela C; Steyger, Peter S

    2015-11-01

    Hearing loss in neonatal intensive care unit (NICU) graduates range from 2% to 15% compared to 0.3% in full-term births, and the etiology of this discrepancy remains unknown. The majority of NICU admissions receive potentially ototoxic aminoglycoside therapy, such as gentamicin, for presumed sepsis. Endotoxemia and inflammation are associated with increased cochlear uptake of aminoglycosides and potentiated ototoxicity in mice. We tested the hypothesis that sepsis or systemic inflammatory response syndrome (SIRS) and intravenous gentamicin exposure increases the risk of hearing loss in NICU admissions. The Institutional Review Board at Oregon Health & Science University (OHSU) approved this study design. Two hundred and eight infants met initial criteria, and written, informed consent were obtained from parents or guardians of 103 subjects ultimately enrolled in this study. Prospective data from 91 of the enrolled subjects at OHSU Doernbecher Children's Hospital Neonatal Care Center were processed. Distortion product otoacoustic emissions (DPOAEs; f2 frequency range: 2063-10,031 Hz) were obtained prior to discharge to assess auditory performance. To pass the DPOAE screen, normal responses in >6 of 10 frequencies in both ears were required; otherwise the subject was considered a "referral" for a diagnostic hearing evaluation after discharge. Cumulative dosing data and diagnosis of neonatal sepsis or SIRS were obtained from OHSU's electronic health record system, and the data processed to obtain risk ratios. Using these DPOAE screening criteria, 36 (39.5%) subjects would be referred. Seventy-four (81%) subjects had intravenous gentamicin exposure. Twenty (22%) had ≥4 days of gentamicin, and 71 (78%) had sepsis or met neonatal SIRS criteria, 9 of whom had ≥5 days of gentamicin and a DPOAE referral risk ratio of 2.12 (p=0.02) compared to all other subjects. Combining subjects with either vancomycin or furosemide overlap with gentamicin treatment yielded an almost

  7. Effects of gentamicin on choline acetyltransferase expression in paraolivary nucleus neurons of guinea pigs

    Institute of Scientific and Technical Information of China (English)

    Mingguang Zhao; Xiaochen Wang; Yong Liang; Peng Xie; Xuejun Guo; Jinjiang Li; Wei Wang

    2008-01-01

    BACKGROUND: It is generally accepted that gentamicin can damage the cochlear nerve and acoustic nerve. In recent years, scholars have focused on neuronal changes and neurochemical information in the brainstem primary auditory center. OBJECTIVE: To explore morphological changes of choline acetyltransferase (ChAT)-positive neurons in the paraolivary nucleus (PON) of guinea pigs, and the effect on hearing following gentamicin injection. DESIGN, TIME AND SETTING: Randomized grouping and morphological observational study was performed at Animal Experimental Center of General Hospital of Shenyang Military Area Command of Chinese PLA from January to August 2007. MATERIALS: A total of 48 healthy guinea pigs were randomly divided into model (n = 40) and control (n = 8) groups. The model group was divided into five subgroups at five time points of I and 3 days, 1, 2, and 3 weeks. METHODS: Guinea pigs in the model group were intraperitoneally injected with gentamicin, and those in the control group were intraperitoneally injected with the same volume of saline. MAIN OUTCOME MEASURES: Auditory brainstem-evoked potential was used to record auditory threshold; distribution and morphological changes of ChAT-positive neurons in the PON were observed with immunohistochemistry; section area and gray value of ChAT-positive neurons were measured with Quantimet 570 image-analyzing system. RESULTS: ChAT-positive neurons were diffusedly distributed in the PON. The majority was composed of large, round cells, with positive neurites that could be clearly observed. Following gentamicin injection, the positive neurons displayed an irregular outline, and their neurites began to shorten and disappear. The gray value increased with prolonged gentamicin administration (P < 0.05). In addition, the somatic cross-sectional area was enlarged in the model group at 1 and 3 days after injection (P < 0.05), whereas cell number significantly decreased at three weeks after injection (P < 0.05). Starting

  8. Effect of Tephrosia purpurea (L.) Pers. Leaves on Gentamicin-Induced Nephrotoxicity in Rats

    OpenAIRE

    JAIN, Avijeet; NAHATA, Alok; SINGHAI, Abhay

    2013-01-01

    The aim of the study was to evaluate the nephroprotective and nephrocurative effects of Tephrosia purpurea (L.) Pers. leaves against gentamicin-induced acute renal injury in albino rats. The maximum free radical scavenging activity of the ethanolic extract was the basis for the selection of this extract for the in vivo study. Gentamicin (40 mg/kg, s.c.) was administered to induce toxicity in the toxic group and the ethanolic extract (200 mg/kg p.o.) was administered in all treated groups. Blo...

  9. Chemopreventive role of Coriandrum sativum against gentamicin-induced renal histopathological damage in rats

    Directory of Open Access Journals (Sweden)

    Lakhera Abhijeet

    2015-06-01

    Full Text Available Drug induced nephrotoxicity is one of the most common causes of renal failure. Gentamicin belongs to aminoglycosides, which elicit nephrotoxic potential. Natural antioxidants from plants demonstrate a number of biotherapeutic activities. Coriander is an important medicinal plant known for its hepatoprotective, diuretic, carminative, digestive and antihelminthic potential. This study was designed to investigate whether the extract of Coriandrum sativum ameliorates the nephrotoxicity induced by gentamicin in rats. Dried coriander powder was coarsely grinded and subjected to defatting by petroleum ether and further with ethyl acetate. The extract was filtered and subjected to phytochemical and phytoanalytical studies.

  10. Kinetics and dose calculations of ampicillin and gentamicin given as continuous intravenous infusion during parenteral nutrition in 88 newborn infants

    DEFF Research Database (Denmark)

    Colding, H; Møller, S; Bentzon, M W

    1983-01-01

    Ampicillin and gentamicin were administered continuously intravenously to 88 newborn infants using individually calculated dosages. For infants with a mean value of plasma clearance of the antibiotics, it was calculated that the serum ampicillin and gentamicin concentrations would be between 35...

  11. Kinetics and dose calculations of ampicillin and gentamicin given as continuous intravenous infusion during parenteral nutrition in 88 newborn infants

    DEFF Research Database (Denmark)

    Colding, H; Møller, S; Bentzon, M W

    1983-01-01

    Ampicillin and gentamicin were administered continuously intravenously to 88 newborn infants using individually calculated dosages. For infants with a mean value of plasma clearance of the antibiotics, it was calculated that the serum ampicillin and gentamicin concentrations would be between 35-5...

  12. Carissa carandas Linn. fruit extract ameliorates gentamicin-induced nephrotoxicity in rats via attenuation of oxidative stress

    Institute of Scientific and Technical Information of China (English)

    Jayesh B. Dhodi; Deepavali R. Thanekar; Snehal N. Mestry; Archana R. Juvekar

    2015-01-01

    Objective: To elucidate the mechanism of action of methanolic extract of Carissa carandas fruits (MCCF) in attenuation of diabetic nephropathy using gentamicin induced nephrotoxicity model.Methods:Extract was daily administered to Sprague Dawley rats at doses of 100, 200 and 400 mg/kg for 8 days along with intramuscular injection of gentamicin (80 mg/kg). After completion of the study, serum was analyzed for blood urea nitrogen, albumin and creatinine; urine (24 h) was analyzed for albumin and creatinine. Kidney was evaluated for its biochemical and morphological changes. Results: Extract at doses of 200 and 400 mg/kg significantly normalized the nephrotoxic biomarkers in serum and urine and increased the kidney antioxidant activities which were altered due to gentamicin toxicity. The histological findings reveal that MCCF was capable of protecting the kidney against gentamicin toxicity. Conclusions: Extract ameliorated oxidative stress generated by gentamicin administration, which is one of the mechanisms for its preventive action against diabetic nephropathy.

  13. Severity of gentamicin's nephrotoxic effect on patients with infective endocarditis: a prospective observational cohort study of 373 patients

    DEFF Research Database (Denmark)

    Buchholtz, Kristine; Larsen, Carsten T; Hassager, Christian;

    2009-01-01

    and mortality in patients with IE. METHODS: A prospective observational cohort study was performed at 2 tertiary university hospitals in Copenhagen from October 2002 through October 2007; 373 consecutive patients with IE were included. A total of 287 (77%) of the patients received gentamicin treatment (median...... duration, 14 days); dosage was adjusted according to daily serum creatinine and trough serum gentamicin levels. Kidney function was determined by estimated endogenous creatinine clearance (EECC). Statistical correlation between gentamicin and EECC change was analyzed, and the association between mortality...... and nephrotoxicity was investigated. RESULTS: The primary bacteriological etiologies were as follows: Streptococcus species (37.1%), Staphylococcus aureus (18.2%), and Enterococcus species (16.1%). In the gentamicin group, the mean EECC change was an 8.6% decrease, but in the no-gentamicin group, the mean change...

  14. Passive sampling in regulatory chemical monitoring of nonpolar organic compounds in the aquatic environment

    NARCIS (Netherlands)

    Booij, K.; Robinson, C.D.; Burgess, R.M.; Mayer, P.; Roberts, C.A.; Ahrens, L.; Allan, I.J.; Brant, J.; Jones, L.; Kraus, U.R.; Larsen, M.M.; Lepom, P.; Petersen, J.; Pröfrock, D.; Roose, P.; Schäfer, S.; Smedes, F.; Tixier, C.; Vorkamp, K.; Whitehouse, P.

    2016-01-01

    We reviewed compliance monitoring requirements in the EuropeanUnion, the United States, and the Oslo-Paris Convention for the protection of themarine environment of the North-East Atlantic, and evaluated if these are met bypassive sampling methods for nonpolar compounds. The strengths andshortcoming

  15. Determinatin of the Dipole Moment of Polar Compounds in Nonpolar Solvents.

    Science.gov (United States)

    Janini, George M.; Katrib, Ali H.

    1983-01-01

    Proposes a simple experiment based on the procedure of Guggenheim and Smith for the determinatin of the dipole moments of two isomeric compounds in nonpolar solvents. Provides background information, laboratory procedures, sample data, results of least squares analysis and discussion of results. (JM)

  16. Surface chemistry and electronic structure of nonpolar and polar GaN films

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Monu; Krishna, T.C. Shibin; Aggarwal, Neha; Gupta, Govind, E-mail: govind@nplindia.org

    2015-08-01

    Highlights: • Surface chemistry and electronic structure of polar and nonpolar GaN is reported. • Influence of polarization on electron affinity of p & np GaN films is investigated. • Correlation between surface morphology and polarity has been deduced. - Abstract: Photoemission and microscopic analysis of nonpolar (a-GaN/r-Sapphire) and polar (c-GaN/c-Sapphire) epitaxial gallium nitride (GaN) films grown via RF-Molecular Beam Epitaxy is reported. The effect of polarization on surface properties like surface states, electronic structure, chemical bonding and morphology has been investigated and correlated. It was observed that polarization lead to shifts in core level (CL) as well as valence band (VB) spectra. Angle dependent X-ray Photoelectron Spectroscopic analysis revealed higher surface oxide in polar GaN film compared to nonpolar GaN film. On varying the take off angle (TOA) from 0° to 60°, the Ga−O/Ga−N ratio varied from 0.11–0.23 for nonpolar and 0.17–0.36 for polar GaN film. The nonpolar film exhibited N-face polarity while Ga-face polarity was perceived in polar GaN film due to the inherent polarization effect. Polarization charge compensated surface states were observed on the polar GaN film and resulted in downward band bending. Ultraviolet photoelectron spectroscopic measurements revealed electron affinity and ionization energy of 3.4 ± 0.1 eV and 6.8 ± 0.1 eV for nonpolar GaN film and 3.8 ± 0.1 eV and 7.2 ± 0.1 eV for polar GaN film respectively. Field Emission Scanning Electron Microscopy measurements divulged smooth morphology with pits on polar GaN film. The nonpolar film on the other hand showed pyramidal structures having facets all over the surface.

  17. In vitro activity of daptomycin in combination with β-lactams, gentamicin, rifampin, and tigecycline against daptomycin-nonsusceptible enterococci.

    Science.gov (United States)

    Hindler, Janet A; Wong-Beringer, Annie; Charlton, Carmen L; Miller, Shelley A; Kelesidis, Theodoros; Carvalho, Marissa; Sakoulas, George; Nonejuie, Poochit; Pogliano, Joseph; Nizet, Victor; Humphries, Romney

    2015-07-01

    Enterococci that are nonsusceptible (NS; MIC > 4 μg/ml) to daptomycin are an emerging clinical concern. The synergistic combination of daptomycin plus beta-lactams has been shown to be effective against vancomycin-resistant Enterococcus (VRE) species in vitro. This study systematically evaluated by in vitro time-kill studies the effect of daptomycin in combination with ampicillin, cefazolin, ceftriaxone, ceftaroline, ertapenem, gentamicin, tigecycline, and rifampin, for a collection of 9 daptomycin-NS enterococci that exhibited a broad range of MICs and different resistance-conferring mutations. We found that ampicillin plus daptomycin yielded the most consistent synergy but did so only for isolates with mutations to the liaFSR system. Daptomycin binding was found to be enhanced by ampicillin in a representative isolate with such mutations but not for an isolate with mutation to the yycFGHIJ system. In contrast, ampicillin enhanced the killing of the LL-37 human antimicrobial peptide against daptomycin-NS E. faecium with either the liaFSR or yycFGHIJ mutation. Antagonism was noted only for rifampin and tigecycline and only for 2 or 3 isolates. These data add support to the growing body of evidence indicating that therapy combining daptomycin and ampicillin may be helpful in eradicating refractory VRE infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Population pharmacokinetics and relationship between demographic and clinical variables and pharmacokinetics of gentamicin in neonates

    NARCIS (Netherlands)

    Stolk, L M L; Degraeuwe, P L J; Nieman, F H M; de Wolf, M C; de Boer, A

    2002-01-01

    Population pharmacokinetic parameter estimates were calculated from 725 routine plasma gentamicin concentrations obtained in 177 neonates of 24 to 42 weeks' gestational age in their first week of life. Kel increases and V/W decreases with increasing gestational age. Almost identical results were obt

  19. Effects of intratympanic gentamicin on vestibular afferents and hair cells in the chinchilla.

    Science.gov (United States)

    Hirvonen, Timo P; Minor, Lloyd B; Hullar, Timothy E; Carey, John P

    2005-02-01

    Gentamicin is toxic to vestibular hair cells, but its effects on vestibular afferents have not been defined. We treated anesthetized chinchillas with one injection of gentamicin (26.7 mg/ml) into the middle ear and made extracellular recordings from afferents after 5-25 (early) or 90-115 days (late). The relative proportions of regular, intermediate, and irregular afferents did not change after treatment. The spontaneous firing rate of regular afferents was lower (P galvanic currents was unaffected for all afferents. Intratympanic gentamicin treatment reduced the histological density of all hair cells by 57% (P = 0.04). The density of hair cells with calyx endings was reduced by 99% (P = 0.03), although some remaining hair cells had other features suggestive of type I morphology. Type II hair cell density was not significantly reduced. These findings suggest that a single intratympanic gentamicin injection causes partial damage and loss of vestibular hair cells, particularly type I hair cells or their calyceal afferent endings, does not damage the afferent spike initiation zones, and preserves enough hair cell synaptic activity to drive the spontaneous activity of vestibular afferents.

  20. Leishmanicidal Activity of Films Containing Paromomycin and Gentamicin Sulfate both In Vitro and In Vivo.

    Science.gov (United States)

    Tolouei, S; Hasheminia, Sj; Narimani, M; Khamesipour, A; Shatalebi, Ma; Hejazi, Sh

    2011-08-01

    Based on the efficacy of paromomycin ointment and recent ongoing clinical trials of combination of paromomycin and gentamicin, a new physical form of films of the paromomycin and gentamicin was prepared and anti-Leishmania activities of the prepared films were assessed in vitro and in vivo. Paromomycin 15% and gentamicin 0.5% was incorporated in a film using ethyl cellulose and HPMC (Hydroxyl Propyl Methyl Cellulose). In order to assess the drug release and anti-Leishmania activities of the preparation, a clone L. major parasite was established using a set of modified NNN medium without overlay liquid layer. Therapeutic effects of the films were evaluated using Balb/c mice model. The mice were inoculated with 2×10(6)L. major promastigotes (MRHO/IR/75/ER) and then when the lesions developed the mice were randomly divided in 3 groups, 10 mice per group, and treated with either perpetrated films or placebo for 28 days or left untreated. Growth inhibition of cloned promastigotes showed that the films have enough releasing capacity and in vivo system, the films containing paromomycin and gentamicin was able to reduce the lesion size and induced complete cure in 80% of the mice but relapse was seen in 60% of the cured mice and overall 50% cure rate was seen during 20 weeks period of the study. It seems that the prepared films might be further used in human clinical trials.

  1. Gentamicin induced nitric oxide-related oxidative damages on vestibular afferents in the guinea pig.

    Science.gov (United States)

    Hong, Sung Hwa; Park, Sook Kyung; Cho, Yang-Sun; Lee, Hyun-Seok; Kim, Ki Ryung; Kim, Myung Gu; Chung, Won-Ho

    2006-01-01

    Gentamicin is a well-known ototoxic aminoglycoside. However, the mechanism underlying this ototoxicity remains unclear. One of the mechanisms which may be responsible for this ototoxicity is excitotoxic damage to hair cells. The overstimulation of the N-methyl-d-aspartate (NMDA) receptors increases the production of nitric oxide (NO), which induces oxidative stress on hair cells. In order to determine the mechanism underlying this excitotoxicity, we treated guinea pigs with gentamicin by placing gentamicin (0.5 mg) pellets into a round window niche. After the sacrifice of the animals, which occurred at 3, 7 and 14 days after the treatment, the numbers of hair cells in the animals were counted with a scanning electron microscope. We then performed immunostaining using neuronal nitric oxide synthase (nNOS), inducible NOS (iNOS) and nitrotyrosine antibodies. The number of hair cells in the animals was found to decrease significantly after 7 days. nNOS and iNOS expression levels were observed to have increased 3 days after treatment. Nitrotyrosine was expressed primarily at the calyceal afferents of the type I hair cells 3 days after treatment. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) staining revealed positive hair cells 3 days after treatment. Our results suggest that inner ear treatment with gentamicin may upregulate nNOS and iNOS to induce oxidative stress in the calyceal afferents of type I hair cells, via nitric oxide overproduction.

  2. Novel model-based dosing guidelines for gentamicin and tobramycin in preterm and term neonates

    NARCIS (Netherlands)

    P.A.J. Välitalo (Pyry A. J.); J.N. van den Anker (John); K. Allegaert (Karel); R.F.W. de Cock (Roosmarijn); M. de Hoog (Matthijs); S.H. Simons (Sinno); J.W. Mouton (Johan); C.A.J. Knibbe (Catherijne)

    2015-01-01

    textabstractObjectives: In the heterogeneous group of preterm and term neonates, gentamicin and tobramycin are mainly dosed according to empirical guidelines, after which therapeutic drug monitoring and subsequent dose adaptation are applied. In view of the variety of neonatal guidelines available,

  3. Preparation, characterization, and in vitro release of gentamicin from coralline hydroxyapatite-alginate composite microspheres.

    Science.gov (United States)

    Sivakumar, M; Rao, K Panduranga

    2003-05-01

    In this work, composite microspheres were prepared from bioactive ceramics such as coralline hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] granules, a biodegradable polymer, sodium alginate, and an antibiotic, gentamicin. Previously, we have shown a gentamicin release from coralline hydroxyapatite granules-chitosan composite microspheres. In the present investigation, we attempted to prepare composite microspheres containing coralline hydroxyapatite granules and sodium alginate by the dispersion polymerization technique with gentamicin incorporated by absorption method. The crystal structure of the composite microspheres was analyzed using X-ray powder diffractometer. Fourier transform infrared spectra clearly indicated the presence of per-acid of sodium alginate, phosphate, and hydroxyl groups in the composite microspheres. Scanning electron micrographs and optical micrographs showed that the composite microspheres were spherical in shape and porous in nature. The particle size of composite microspheres was analyzed, and the average size was found to be 15 microns. The thermal behavior of composite microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis. The cumulative in vitro release profile of gentamicin from composite microspheres showed near zero order patterns.

  4. Lack of protection against gentamicin ototoxicity by auditory conditioning with noise

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    Alex Strose

    2014-10-01

    Full Text Available INTRODUCTION: Auditory conditioning consists of the pre-exposure to low levels of a potential harmful agent to protect against a subsequent harmful presentation. OBJECTIVE: To confirm if conditioning with an agent different from the used to cause the trauma can also be effective. METHOD: Experimental study with 17 guinea pigs divided as follows: group Som: exposed to 85 dB broadband noise centered at 4 kHz, 30 minutes a day for 10 consecutive days; group Cont: intramuscular administration of gentamicin 160 mg/kg a day for 10 consecutive days; group Expt: conditioned with noise similarly to group Som and, after each noise presentation, received gentamicin similarly to group Cont. The animals were evaluated by distortion product otoacoustic emissions (DPOAEs, brainstem auditory evoked potentials (BAEPs and scanning electron microscopy. RESULTS: The animals that were conditioned with noise did not show any protective effect compared to the ones that received only the ototoxic gentamicin administration. This lack of protection was observed functionally and morphologically. CONCLUSION: Conditioning with 85 dB broadband noise, 30 min a day for 10 consecutive days does not protect against an ototoxic gentamicin administration of 160 mg/kg a day for 10 consecutive days in the guinea pig.

  5. Continuous intravenous infusion of ampicillin and gentamicin during parenteral nutrition in 88 newborn infants

    DEFF Research Database (Denmark)

    Colding, H; Møller, S; Andersen, G E

    1982-01-01

    Ampicillin and gentamicin were dissolved once a day in an L-amino acid solution especially prepared for parenteral nutrition of newborn infants and infused continuously to 88 infants in whom septicaemia was suspected or had been proved. The mean dosages were 162 and 5.3 mg/kg per 24 hours...

  6. Administration of gentamicin and ampicillin by continuous intravenous infusion to newborn infants during parenteral nutrition

    DEFF Research Database (Denmark)

    Colding, H; Andersen, G E

    1982-01-01

    Gentamicin and ampicillin were dissolved in an L-amino acid solution especially prepared for newborn infants and infused intravenously over 24 h in 7 babies with serious neonatal surgical problems. Serum concentrations of the antibiotics were maintained rather constant and well above the minimal ...

  7. N-ACETYLCYSTEINE EFFECT ON GENTAMICIN INDUCED NEPHROTOXICITY IN ANIMAL MODELS

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    Laishram Elizabeth

    2016-05-01

    Full Text Available BACKGROUND Gentamicin exerts a unique pharmacokinetic effect on renal physiology and its use at high dose or prolonged treatment requires monitoring of kidney function test. Antioxidants has been claimed to have nephroprotective potential and hence antioxidant compound, N-acetylcysteine (NAC has been used in renal impairment; however, its efficacy is not very well documented. Therefore, the present study has been undertaken to evaluate the role of antioxidant (NAC in impaired kidney function due to high dose Gentamicin in rat models. Gentamicin at the dose of 80 mg/kg b.w. intramuscularly was given in 18 adult healthy albino rats for 10 days and varying doses of antioxidant NAC (20 and 40 mg/kg were given orally for 3 wks. starting from day 5 of the experiment. Blood urea and creatinine levels were measured on day 5, 10 and after completion of treatment of NAC and histopathology examination conducted. Intramuscular injection of high dose of Gentamicin significantly produced biochemical signs of nephrotoxicity. Serum creatinine levels were significantly lowered in NAC treated group compared to the control group. The group treated with NAC 40 mg/kg for 3 wks. had significantly lowered renal biochemical parameters and histopathological features compared to control.

  8. The pharmacokinetics and tissue levels of polymyxin B, colistin and gentamicin in calves.

    Science.gov (United States)

    Ziv, G; Nouws, J F; van Ginneken, C A

    1982-03-01

    Following a single intravenous injection of polymyxin B, colistin (5 mg/kg, each) and gentamicin (3 mg/kg) to calves, the decline in serum antibiotic concentration generally suggested a three-compartment (open system) pharmacokinetic model. Tissue binding is a dominant factor in the distribution and elimination kinetics of the drugs. Less than 65% of the dose of polymyxin B and colistin was recovered in the urine during 48 h after treatment. Concentrations of nonbound polymyxin B and colistin in the kidney, liver, lung, heart, and skeletal muscles were similar to total (free and bound) serum drug levels, but considerably higher concentrations were found, in bound form, in chloroform-ethanol extracts of these organs. At 24 h after treatment, more than 50% of the doses of polymyxin B and colistin were present bound to the tissues; the largest amount was in the skeletal muscles. Gentamicin was concentrated in the kidney, predominantly in the free form. At 48 h after treatment the amount of gentamicin in the kidney was 6.3% of the administered dose, being more than five times greater than the corresponding amounts of polymyxin B and colistin. The extent of tissue uptake of polymyxin B and colistin limits the usefulness of kinetic values, which are derived from the analysis of serum drug levels, for the purpose of designing dosage schedules. The strong affinity of the polymyxins to the muscle tissue, and gentamicin to the kidney, can result in drug residues persisting in the body for several weeks.

  9. 21 CFR 524.1044d - Gentamicin sulfate, betamethasone valerate ointment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Gentamicin sulfate, betamethasone valerate ointment. 524.1044d Section 524.1044d Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... preparation. Administration of recommended doses beyond 7 days may result in delayed wound healing. Animals...

  10. Gentamicin pharmacokinetics in preterm infants with a patent and a closed ductus arteriosus

    NARCIS (Netherlands)

    Touw, D J; Proost, J H; Stevens, R; Lafeber, H N; van Weissenbruch, M M

    2001-01-01

    BACKGROUND AND AIM: A patent ductus arteriosus (PDA) may influence renal and hepatic blood flow and hence pharmacokinetics of drugs in neonates compared to neonates with a closed ductus arteriosus (CDA). A 10-percent difference of gentamicin pharmacokinetic parameters between PDA and CDA has been re

  11. Continuous intravenous infusion of ampicillin and gentamicin during parenteral nutrition in 88 newborn infants

    DEFF Research Database (Denmark)

    Colding, H; Møller, S; Andersen, G E

    1982-01-01

    Ampicillin and gentamicin were dissolved once a day in an L-amino acid solution especially prepared for parenteral nutrition of newborn infants and infused continuously to 88 infants in whom septicaemia was suspected or had been proved. The mean dosages were 162 and 5.3 mg/kg per 24 hours...

  12. Single Daily Dosing of Gentamicin: Pharmacokinetic Comparison of Two Dosing Methodologies for Postpartum Endometritis

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    C. Liu

    1999-01-01

    Full Text Available Objective: We compared the pharmacokinetics of two methods for dosing gentamicin for the treatment of postpartum endometritis with the goal of achieving adequate peak serum concentrations (>12 mg/L and prolonged trough levels below 2 mg/L.

  13. The Effects of Vitamin D on Gentamicin-Induced Acute Kidney Injury in Experimental Rat Model

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    Ender Hur

    2013-01-01

    Full Text Available Introduction. Acute kidney injury (AKI pathogenesis is complex. Findings of gentamicin nephrotoxicity are seen in 30% of the AKI patients. Vitamin D has proven to be effective on renin expression, inflammatory response, oxidative stress, apoptosis, and atherosclerosis. We aimed to investigate the effect of vitamin D in an experimental rat model of gentamicin-induced AKI. Methods. Thirty nonuremic Wistar albino rats were divided into 3 groups: Control group, 1 mL saline intramuscular (im daily; Genta group, gentamicin 100 mg/kg/day (im; Genta + vitamin D, gentamicin 100 mg/kg/day (im in addition to 1α, 25 (OH2D3 0.4 mcg/kg/day subcutaneously for 8 days. Blood pressures and 24-hour urine were measured. Blood urea and creatinine levels and urine tubular injury markers were measured. Renal histology was semiquantitatively assessed. Results. Urea, creatinine and urine neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 were all increased in Genta group indicating AKI model. Systolic blood pressure decreased, but urine volume and glutathione increased in Genta + Vit D group compared to Control group. Histological scores indicating tubular injury increased in Genta and Genta + Vit D groups. Conclusions. Vitamin D does not seem to be effective on histological findings although it has some beneficial effects via RAS system and a promising effect on antioxidant system.

  14. Microbubble-Mediated Ultrasound Enhances the Lethal Effect of Gentamicin on Planktonic Escherichia coli

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    Han-Xiao Zhu

    2014-01-01

    Full Text Available Previous research has found that low-intensity ultrasound enhanced the lethal effect of gentamicin on planktonic E. coli. We aimed to further investigate whether microbubble-mediated low-intensity ultrasound could further enhance the antimicrobial efficacy of gentamicin. The planktonic E. coli (ATCC 25922 was distributed to four different interventions: control (GCON, microbubble only (GMB, ultrasound only (GUS, and microbubble-mediated ultrasound (GMUS. Ultrasound was applied with 100 mW/cm2 (average intensity and 46.5 KHz, which presented no bactericidal activity. After 12 h, plate counting was used to estimate the number of bacteria, and bacterial micromorphology was observed with transmission electron microscope. The results showed that the viable counts of E. coli in GMUS were decreased by 1.01 to 1.42 log10 CFU/mL compared with GUS (P<0.01. The minimal inhibitory concentration (MIC of gentamicin against E. coli was 1 μg/mL in the GMUS and GUS groups, lower than that in the GCON and GMB groups (2 μg/mL. Transmission electron microscopy (TEM images exhibited more destruction and higher thickness of bacterial cell membranes in the GMUS than those in other groups. The reason might be the increased permeability of cell membranes for gentamicin caused by acoustic cavitation.

  15. A new dosing schedule for gentamicin in blood pythons (Python curtus): a pharmacokinetic study.

    Science.gov (United States)

    Hilf, M; Swanson, D; Wagner, R; Yu, V L

    1991-03-01

    Gentamicin is frequently used in the treatment of aerobic Gram-negative infections in reptiles. Pharmacokinetic data to ensure proper dosing are scant, especially for large snakes. A pharmacokinetic study of gentamicin was therefore conducted in four blood pythons. Snakes were given intramuscular injections of either 2.5 mg kg-1 or 3.0 mg kg-1 loading dose followed by 1.5 mg kg-1 at 72 and 96 hours. A linear pharmacokinetic relationship between gentamicin serum concentrations and time was demonstrated in each of the four snakes studied. Peak serum concentrations occurred six to 10 hours after injection and ranged from 4.6 to 8.9 micrograms ml-1. Half-life was variable and ranged from 32 to 110 hours. Total body clearance and apparent volume of distribution varied little between the individual snakes studied. There was no evidence of renal toxicity. For blood pythons a loading dose of 2.5 mg kg-1 followed by 1.5 mg kg-1 at 96 hour intervals is recommended. If higher concentrations are desired, a loading dose of 3.0 mg kg-1 followed by 1.5 mg kg-1 at 96 hours can be given. These dosing schedules will provide serum concentrations in excess of the minimum inhibitory concentrations for most aerobic Gram-negative bacilli that are pathogenic in snakes; gentamicin accumulation with subsequent renal dysfunction should not occur.

  16. In-vitro analysis of the effect of gentamicin and polyhexanide on bone tissue.

    Science.gov (United States)

    Kock, Hans-Jürgen; Ernst, Dirk; Jethon, Frank; Fabry, Werner

    2013-04-01

    Though anti-infectives have been used for a long time in surgical procedures, the effect on bone tissue has not been determined for most antibiotics and antiseptics. In our in vitro study, 4x4x8 mm(3) blocks of rabbit cancellous bone tissue were incubated with Ringer's solution, gentamicin and Lavasorb(®) each for time intervals of 15 minutes, 30 minutes, one hour, four hours and eight hours. Samples were examined double blinded through optical and electron microscopy. Tissue degeneration was observed in all samples. It was low in Ringer's solution. Samples with Lavasorb showed a moderate degeneration after 15 and 30 minutes, which was accelerated after one hour. Gentamicin led to a moderate degeneration of bone tissue after 15 and 30 minutes and to a more accelerated degeneration after one hour. The effect of gentamicin on bone tissue was more pronounced than the effect of Lavasorb. This investigation showed that local application of Lavasorb or gentamicin on bone tissue should be restricted to 30 minutes, while Lavasorb showed a better tissue tolerability. This finding could have clinical implications for the management of wounds with open osseous tissue and should be further investigated by in vivo studies.

  17. Effect of two cleaning processes for bone allografts on gentamicin impregnation and in vitro antibiotic release.

    Science.gov (United States)

    Coraça-Huber, D C; Hausdorfer, J; Fille, M; Steidl, M; Nogler, M

    2013-06-01

    Bone allografts are a useful and sometimes indispensable tool for the surgeon to repair bone defects. Microbial contamination is a major reason for discarding allografts from bone banks. To improve the number of safe allografts, we suggest chemical cleaning of the grafts followed by antibiotic impregnation. Comparison of two chemical cleaning processes for bone allografts aiming for antibiotic impregnation and consequently delivery rates in vitro. Bone chips of 5-10 mm were prepared from human femoral heads. Two cleaning methods (cleaning A and cleaning B) based on solutions containing hydrogen peroxide, paracetic acid, ethanol and biological detergent were carried out and compared. After the cleaning processes, the bone chips were impregnated with gentamicin. Bacillus subtilis bioassay was used to determine the gentamicin release after intervals of 1-7 days. Differences were compared with non-parametric Mann-Whitney U tests. The zones of inhibition obtained from the bone grafts cleaned with both cleaning processes were similar between the groups. The concentration of the released antibiotic was decreasing gradually over time, following a similar pattern for both groups. The cleaning procedure A as well as the cleaning procedure B for bone allografts allowed the impregnation with gentamicin powder in the same concentrations in both groups. The delivery of gentamicin was similar for both groups. Both cleaning procedures were easy to be carried out, making them suitable for routine use at the bone banks.

  18. Chemopreventive role of Coriandrum sativum against gentamicin-induced renal histopathological damage in rats.

    Science.gov (United States)

    Lakhera, Abhijeet; Ganeshpurkar, Aditya; Bansal, Divya; Dubey, Nazneen

    2015-06-01

    Drug induced nephrotoxicity is one of the most common causes of renal failure. Gentamicin belongs to aminoglycosides, which elicit nephrotoxic potential. Natural antioxidants from plants demonstrate a number of biotherapeutic activities. Coriander is an important medicinal plant known for its hepatoprotective, diuretic, carminative, digestive and antihelminthic potential. This study was designed to investigate whether the extract of Coriandrum sativum ameliorates the nephrotoxicity induced by gentamicin in rats. Dried coriander powder was coarsely grinded and subjected to defatting by petroleum ether and further with ethyl acetate. The extract was filtered and subjected to phytochemical and phytoanalytical studies. Acute toxicity in Wistar rats was determined by the OECD Guideline (423). Animals were divided into four groups. The first group served as positive control, while the second group was toxic control (gentamicin treated). The third and fourth group were treated with the extract (200 and 400 mg/kg gentamicin). After 8 days, the animals were sacrificed and biochemical and histopathological studies were carried out. Phytochemical screening of the extract demonstrated Coriandrum sativum to be rich in flavonoids, polyphenolics and alkaloids. Results of acute toxicity suggested the use of 200 mg/kg and 400 mg/kg for Coriandrum sativum in the study. Coriandrum sativum extract at the dose of 400 mg/kg significantly (pCoriandrum sativum extract ameliorated renal histological lesions. It is concluded that Coriandrum sativum is a potential source of nephroprotective phytochemical activity, with flavonoids and polyphenols as the major components.

  19. Staphylococcus aureus biofilm formation on different gentamicin-loaded polymethylmethacrylate bone cements

    NARCIS (Netherlands)

    van de Belt, H; Neut, D; Schenk, W; van Horn, [No Value; van der Mei, HC; Busscher, HJ

    In this in vitro study, the formation of a Staphylococcus aureus biofilm on six gentamicin-loaded bone cements (CMW1, CMW3, CMW Endurance, CMW2000, Palacos. and Palamed) was determined in a modified Robbins device over a 3 days time span and related with previously (Van de Belt et al., Biomaterials

  20. Staphylococcus aureus biofilm formation on different gentamicin-loaded polymethylmethacrylate bone cements

    NARCIS (Netherlands)

    van de Belt, H; Neut, D; Schenk, W; van Horn, [No Value; van der Mei, HC; Busscher, HJ

    2001-01-01

    In this in vitro study, the formation of a Staphylococcus aureus biofilm on six gentamicin-loaded bone cements (CMW1, CMW3, CMW Endurance, CMW2000, Palacos. and Palamed) was determined in a modified Robbins device over a 3 days time span and related with previously (Van de Belt et al., Biomaterials

  1. Changes in renal enzyme activities following the administration of gentamicin to unilateral nephrectomized rats.

    Science.gov (United States)

    Avidan, G; Aladjem, M; Israeli, B A; Bogin, E

    1986-02-28

    The effects of unilateral nephrectomy and the impact of gentamicin administration on renal tissue enzyme activities in adult Wistar rats were investigated. Gentamicin 200 mg/kg body wt. or an equivalent volume of saline to control rats was administered subcutaneously on three consecutive days, followed by unilateral nephrectomy. Rats were killed on day 3, 7 or 14 following nephrectomy. Alkaline phosphatase, predominantly a proximal tubular brush border enzyme, rose in both the experimental and control groups, however, significantly less in the gentamicin treated rats. Aspartate aminotransferase activity, an enzyme participating in renal glucogenesis, increased transiently in the control but remained unchanged in the experimental group. No difference in glucose-6-phosphate dehydrogenase activity between the two groups was observed, probably reflecting the localization of this enzyme to distal tubular segments, a site unaffected by gentamicin. Significant and similar increases in Mg2+ and Na+ K+ ATPase were observed on day 14 in both groups. The administration of the drug resulted in a marked reduction in oxygen consumption, with a higher oxidation to phosphorylation ratio (P/O). Serum creatinine concentration was significantly higher on days 3 and 7 in the experimental group reverting to control values on the 14th day. Urea concentration increased significantly on days 3 and 7, decreasing on the 14th day to values slightly, but significantly, higher than those of the controls.

  2. Nephroprotective effect of ethanolic extract of abutilon indicum root in gentamicin induced acute renal failure

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    Jacob Jesurun RS

    2016-06-01

    Conclusions: The ethanolic extract of abutilon indicum root has nephron protective effect in gentamicin induced acute renal failure. Nephro protective action in this study could be due to the antioxidant and other phytochemical of abutilon indicum root. [Int J Basic Clin Pharmacol 2016; 5(3.000: 841-845

  3. Effect of endogenous hydrogen sulfide inhibition on structural and functional renal disturbances induced by gentamicin

    Energy Technology Data Exchange (ETDEWEB)

    Francescato, H.D.C.; Chierice, J.R.A.; Marin, E.C.S. [Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Cunha, F.Q. [Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Costa, R.S. [Departamento de Patologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Silva, C.G.A.; Coimbra, T.M. [Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2012-02-17

    Animal models of gentamicin nephrotoxicity present acute tubular necrosis associated with inflammation, which can contribute to intensify the renal damage. Hydrogen sulfide (H{sub 2}S) is a signaling molecule involved in inflammation. We evaluated the effect of DL-propargylglycine (PAG), an inhibitor of endogenous H{sub 2}S formation, on the renal damage induced by gentamicin. Male Wistar rats (N = 8) were injected with 40 mg/kg gentamicin (im) twice a day for 9 days, some of them also received PAG (N = 8, 10 mg·kg{sup −1}·day{sup −1}, ip). Control rats (N = 6) were treated with saline or PAG only (N = 4). Twenty-four-hour urine samples were collected one day after the end of these treatments, blood samples were collected, the animals were sacrificed, and the kidneys were removed for quantification of H{sub 2}S formation and histological and immunohistochemical studies. Gentamicin-treated rats presented higher sodium and potassium fractional excretion, increased plasma creatinine [4.06 (3.00; 5.87) mg%] and urea levels, a greater number of macrophages/monocytes, and a higher score for tubular interstitial lesions [3.50 (3.00; 4.00)] in the renal cortex. These changes were associated with increased H{sub 2}S formation in the kidneys from gentamicin-treated rats (230.60 ± 38.62 µg·mg protein{sup −1}·h{sup −1}) compared to control (21.12 ± 1.63) and PAG (11.44 ± 3.08). Treatment with PAG reduced this increase (171.60 ± 18.34), the disturbances in plasma creatinine levels [2.20 (1.92; 4.60) mg%], macrophage infiltration, and score for tubular interstitial lesions [2.00 (2.00; 3.00)]. However, PAG did not interfere with the increase in fractional sodium excretion provoked by gentamicin. The protective effect of PAG on gentamicin nephrotoxicity was related, at least in part, to decreased H{sub 2}S formation.

  4. Effect of endogenous hydrogen sulfide inhibition on structural and functional renal disturbances induced by gentamicin

    Directory of Open Access Journals (Sweden)

    H.D.C. Francescato

    2012-03-01

    Full Text Available Animal models of gentamicin nephrotoxicity present acute tubular necrosis associated with inflammation, which can contribute to intensify the renal damage. Hydrogen sulfide (H2S is a signaling molecule involved in inflammation. We evaluated the effect of DL-propargylglycine (PAG, an inhibitor of endogenous H2S formation, on the renal damage induced by gentamicin. Male Wistar rats (N = 8 were injected with 40 mg/kg gentamicin (im twice a day for 9 days, some of them also received PAG (N = 8, 10 mg·kg-1·day-1, ip. Control rats (N = 6 were treated with saline or PAG only (N = 4. Twenty-four-hour urine samples were collected one day after the end of these treatments, blood samples were collected, the animals were sacrificed, and the kidneys were removed for quantification of H2S formation and histological and immunohistochemical studies. Gentamicin-treated rats presented higher sodium and potassium fractional excretion, increased plasma creatinine [4.06 (3.00; 5.87 mg%] and urea levels, a greater number of macrophages/monocytes, and a higher score for tubular interstitial lesions [3.50 (3.00; 4.00] in the renal cortex. These changes were associated with increased H2S formation in the kidneys from gentamicin-treated rats (230.60 ± 38.62 µg·mg protein-1·h-1 compared to control (21.12 ± 1.63 and PAG (11.44 ± 3.08. Treatment with PAG reduced this increase (171.60 ± 18.34, the disturbances in plasma creatinine levels [2.20 (1.92; 4.60 mg%], macrophage infiltration, and score for tubular interstitial lesions [2.00 (2.00; 3.00]. However, PAG did not interfere with the increase in fractional sodium excretion provoked by gentamicin. The protective effect of PAG on gentamicin nephrotoxicity was related, at least in part, to decreased H2S formation.

  5. Kinetic and fluid descriptions of charged particle swarms in gases and nonpolar fluids: Theory and applications

    Science.gov (United States)

    Dujko, Sasa

    2016-09-01

    In this work we review the progress achieved over the last few decades in the fundamental kinetic theory of charged particle swarms with the focus on numerical techniques for the solution of Boltzmann's equation for electrons, as well as on the development of fluid models. We present a time-dependent multi term solution of Boltzmann's equation valid for electrons and positrons in varying configurations of electric and magnetic fields. The capacity of a theory and associated computer code will be illustrated by considering the heating mechanisms for electrons in radio-frequency electric and magnetic fields in a collision-dominated regime under conditions when electron transport is greatly affected by non-conservative collisions. The kinetic theory for solving the Boltzmann equation will be followed by a fluid equation description of charged particle swarms in both the hydrodynamic and non-hydrodynamic regimes, highlighting (i) the utility of momentum transfer theory for evaluating collisional terms in the balance equations and (ii) closure assumptions and approximations. The applications of this theory are split into three sections. First, we will present our 1.5D model of Resistive Plate Chambers (RPCs) which are used for timing and triggering purposes in many high energy physics experiments. The model is employed to study the avalanche to streamer transition in RPCs under the influence of space charge effects and photoionization. Second, we will discuss our high-order fluid model for streamer discharges. Particular emphases will be placed on the correct implementation of transport data in streamer models as well as on the evaluation of the mean-energy-dependent collision rates for electrons required as an input in the high-order fluid model. In the last segment of this work, we will present our model to study the avalanche to streamer transition in non-polar fluids. Using a Monte Carlo simulation technique we have calculated transport coefficients for electrons in

  6. Effects of gentamicin on guinea pig vestibular ganglion function and on substance P and neuropeptide Y.

    Science.gov (United States)

    Lin, Chi-Te; Young, Yi-Ho; Cheng, Po-Wen; Lue, June-Horng

    2010-12-01

    Previous studies have demonstrated that following intratympanic gentamicin application in the guinea pigs, vestibular evoked myogenic potentials (VEMPs) were absent regardless of stimulation mode using either air-conducted sound (ACS) stimuli or galvanic vestibular stimulation (GVS). Ultrastructurally, both type I hair cells and their calyx terminals were distorted in the saccular macula. However, little is known about the toxic effects of gentamicin on the vestibular ganglion (VG). In this study, absent ACS- and GVS-VEMPs were noted in all the gentamicin-treated ears (100%), which were confirmed by the substantial loss of sensory hair cells in the saccular macula. Moreover, dramatic up-regulation of growth associated protein-43 (GAP-43) expression was detected in the ipsilateral VG neurons. The mean percentage of substance P-like immunoreactive (SP-LI) neurons in the treated VG (81.8±1.9%) was significantly higher than that in the control VG (68.6±3.3%). Conversely, the mean percentage of neuropeptide Y-like immunoreactive (NPY-LI) neurons in the treated VG (13.7±3.8%) was dramatically lower than that in the control VG (49.0±3.8%). Double labeling results shown 82% of SP-LI and 16% of NPY-LI neurons coexpressed with GAP-43, suggested that SP accumulating coincided with NPY decreasing in regenerating VG neurons after gentamicin treatment. Overall, the changes in SP and NPY expression in VG neurons after gentamicin treatment were like to those in the superior cervical ganglion following sympathectomy.

  7. Gentamicin induces efaA expression and biofilm formation in Enterococcus faecalis.

    Science.gov (United States)

    Kafil, Hossein Samadi; Mobarez, Ashraf Mohabati; Moghadam, Mehdi Forouzandeh; Hashemi, Zahra Sadat; Yousefi, Mehdi

    2016-03-01

    Enterococci have been ranked among the leading causes of nosocomial bacteremia and urinary tract infection. This study aimed to investigate the effect of ampicillin, vancomycin, gentamicin and ceftizoxime on biofilm formation and gene expression of colonization factors on Enterococcus faecalis. Twelve clinical isolates of E. faecalis were used to investigate the effect of antibiotics on biofilm formation and gene expression of efaA, asa1, ebpA, esp and ace. Flow system assay and Microtiter plates were used for biofilm assay. Two hundred clinical isolates were used for confirming the effect of antibiotics on biofilm formation. Ampicillin, vancomycin and ceftizoxime did not have any significant effect on biofilm formation, but gentamicin induced biofilm formation in 89% of isolates. In twelve selected isolate gentamicin increased expression of esp (+50.9%) and efaA (+33.9%) genes and reduced or maintained expression of others (asa1:-47.4%, ebpA: 0, ace:-19.2%). Vancomycin increased expression of esp (+89.1%) but reduced the others (asa1: -34.9%, ebpA:-11%, ace:-30%, efaA:-60%). Ceftizoxime increased slightly ebpA (+19.7%) and reduced others (asa1:-66.2%, esp:-35%, ace:-28.1%, efaA:-38.4%). and ampicillin strongly increased expression of ace (+231%), esp (+131%) and ebpA (+83%) but reduced others (asa1:-85.5%, efaA:-47.4%). The findings of the present study showed that antibiotics may have a role in biofilm formation and sustainability of enterococci, especially in case of gentamicin. efaA gene may have an important role, especially in antibiotic induced biofilm formation by gentamicin. Experiments with efaA mutants are needed to investigate the exact effect of efaA on biofilm formation with antibiotic induced cells.

  8. Pharmacokinetic profile that reduces nephrotoxicity of gentamicin in a perfused kidney-on-a-chip.

    Science.gov (United States)

    Kim, Sejoong; LesherPerez, Sasha Cai; Kim, Byoung Choul C; Yamanishi, Cameron; Labuz, Joseph M; Leung, Brendan; Takayama, Shuichi

    2016-03-24

    Nephrotoxicity is often underestimated because renal clearance in animals is higher compared to in humans. This paper aims to illustrate the potential to fill in such pharmacokinetic gaps between animals and humans using a microfluidic kidney model. As an initial demonstration, we compare nephrotoxicity of a drug, administered at the same total dosage, but using different pharmacokinetic regimens. Kidney epithelial cell, cultured under physiological shear stress conditions, are exposed to gentamicin using regimens that mimic the pharmacokinetics of bolus injection or continuous infusion in humans. The perfusion culture utilized is important both for controlling drug exposure and for providing cells with physiological shear stress (1.0 dyn cm(-2)). Compared to static cultures, perfusion culture improves epithelial barrier function. We tested two drug treatment regimens that give the same gentamycin dose over a 24 h period. In one regimen, we mimicked drug clearance profiles for human bolus injection by starting cell exposure at 19.2 mM of gentamicin and reducing the dosage level by half every 2 h over a 24 h period. In the other regimen, we continuously infused gentamicin (3 mM for 24 h). Although junctional protein immunoreactivity was decreased with both regimens, ZO-1 and occludin fluorescence decreased less with the bolus injection mimicking regimen. The bolus injection mimicking regimen also led to less cytotoxicity and allowed the epithelium to maintain low permeability, while continuous infusion led to an increase in cytotoxicity and permeability. These data show that gentamicin disrupts cell-cell junctions, increases membrane permeability, and decreases cell viability particularly with prolonged low-level exposure. Importantly a bolus injection mimicking regimen alleviates much of the nephrotoxicity compared to the continuous infused regimen. In addition to potential relevance to clinical gentamicin administration regimens, the results are important in

  9. Renal oxidative stress status and histology in gentamicin nephrotoxicity: The effects of antioxidant vitamins

    Directory of Open Access Journals (Sweden)

    R. Ghaznavi

    2006-07-01

    Full Text Available Background: In recent publications, several mechanisms have been implicated in gentamicin (GM nephrotoxicity. Reactive oxygen species have been proposed as one of the causative factors of the drug renal side effects. This study was designed to evaluate the protective effects of the antioxidant vitamins against GM-mediated nephropathy in insitu isolated rat kidneys. Methods: Male Sprague-Dawley rats were randomly assigned to one of the following groups of seven rats: Group 1 (control was tyrode perfused kidneys. Group 2 (GM, 200µg/ml gentamicin was added to the perfusate. Group 3 (GM + Vit C, the same as group 2 but vitamin C (200 mg/L was added to the drinking water for 3 days and 100 mg/L to the perfusate. Group 4 (GM + Vit E, the same as group 2 but vitamin E (100 mg/100 g BW, ip was injected 12 h before experiments. Group 5 (GM + Vit C + Vit E the same as group 2 but Vit E and C were co-administered (same as Group 3 & 4. Urinary N-acetyle-B-D-glucosaminidas (NAG and renal cortex superoxide dismutase (SOD levels were measured and tissue histological evaluations were performed. Results: Gentamicin caused a significant nephrotoxicity demonstrated by increase in urinary NAG. Decline in SOD contents were observed comparing to controls. Vit C or Vit E inhibited the gentamicin-induced increased releases of NAG into urine but did not show a significant effect on the SOD levels. Conclusion: Co-administration of VitC&E significantly prevented the GM nephrotoxicity demonstrating by preservation of SOD levels and prevention of increase in urinary enzyme activities. Histological studies of renal tissues provided additional evidences for protective effects of antioxidant vitamins. We concluded that moderate doses of Vit C & E have protective effects in gentamicin nephrotoxicity and co-administration of these vitamins have additional beneficial effects.

  10. In vitro Antimicrobial Activity of Chlorquinaldol against Microorganisms Responsible for Skin and Soft Tissue Infections: Comparative Evaluation with Gentamicin and Fusidic Acid

    Directory of Open Access Journals (Sweden)

    Monica Bortolin

    2017-06-01

    Full Text Available Skin and soft tissue infections (SSTIs are a major therapeutic challenge for clinicians. The emergence of pathogens with decreased susceptibility to available therapies has become an emerging problem often associated with treatment failure. Hence, there is an urgent need for novel broad-spectrum antimicrobial agents. The purpose of this study was to assess the feasibility of chlorquinaldol as an alternative approach to currently used topical antibiotics for the treatment of skin and soft tissue infections. The activity of chlorquinaldol was investigated against a collection of bacterial isolates responsible for skin infections, including strains resistant to fusidic acid and gentamicin. After determination of MIC and MBC, time-kill experiments were carried out by counting colonies grown after 0, 3, 6, 9, 24, and 48 h of incubation with concentrations equal to ¼×, ½×, 1×, 2×, and 4× MIC of chlorquinaldol, gentamicin, or fusidic acid. Staphylococci resulted the Gram-positives most sensitive to chlorquinaldol, with MIC-values ranging from 0.016 to 0.5 mg/L. A lower activity was observed against Gram-negative bacteria, with 77% of the isolates being inhibited at concentrations ranging from 128 to 512 mg/L. Generally, in time-kill studies, chlorquinaldol showed a bactericidal activity at the higher concentrations (2×, 4× MIC after 24–48 h of incubation. In conclusion, chlorquinaldol may represent a valuable alternative to conventional topical antibiotics for the treatment of skin and soft tissue infections.

  11. Update on new medicinal applications of gentamicin: Evidence-based review

    Directory of Open Access Journals (Sweden)

    Changhua Chen

    2014-02-01

    Full Text Available Gentamicin (GM was discovered in 1963 and was introduced into parenteral usage in 1971. Since then, GM has been widely used in medicinal applications. The Food and Drug Administration of the United States approved the routine prescription of GM to treat the following infectious disorders: infection due to Klebsiella pneumoniae, Escherichia coli, Serratia marcescens, Citrobacter spp., Enterobacteriaceae spp., Pseudomonas spp.; Staphylococcus infectious disease; bacterial meningitis; bacterial sepsis of newborns; bacterial septicemia; infection of the eye, bone, skin and/or subcutaneous tissue; infective endocarditis; peritoneal dialysis–associated peritonitis due to Pseudomonas and other gram-negative organisms; peritonitis due to gastrointestinal tract infections; respiratory tract infections; and urinary tract infectious disease. GM is an old antibiotic and is used widely beyond its FDA-labeled indications as follows: actinomycotic infection; Staphylococcus saprophyticus bacteremia with pyelonephritis; appendicitis; cystic fibrosis; diverticulitis; adjunct regimen for febrile neutropenia; female genital infection; uterine infection; postnatal infection; necrotizing enterocolitis in fetus or newborn; osteomyelitis; pelvic inflammatory disease; plague; gonorrhea; tularemia; prophylaxis of post-cholecystectomy infection, transrectal prostate biopsy, and post–tympanostomy-related infection; malignant otitis externa; and intratympanically or transtympanically for Ménière's disease. GM is also used in combination regimens, such as with beta-lactam antibiotics to treat mixed infection and with bacteriophage to treat Staphylococcus aureus infections. It is also added to medical materials, such as GM-loaded cement spacers for osteomyelitis and prosthetic joint–associated infections. Overall, there are many medicinal applications for GM. To reduce the development of GM-resistant bacteria and to maintain its effectiveness, GM should be used

  12. Naringin ameliorates gentamicin-induced nephrotoxicity and associated mitochondrial dysfunction, apoptosis and inflammation in rats: Possible mechanism of nephroprotection

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Bidya Dhar [Medicinal Chemistry and Pharmacology Division, Indian Institute of Chemical Technology (IICT), Hyderabad 500 007 (India); Tatireddy, Srujana [National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad 500 037 (India); Koneru, Meghana [Medicinal Chemistry and Pharmacology Division, Indian Institute of Chemical Technology (IICT), Hyderabad 500 007 (India); Borkar, Roshan M. [National Centre for Mass Spectrometry, Indian Institute of Chemical Technology (IICT), Hyderabad 500 007 (India); Kumar, Jerald Mahesh [CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad 500 007 (India); Kuncha, Madhusudana [Medicinal Chemistry and Pharmacology Division, Indian Institute of Chemical Technology (IICT), Hyderabad 500 007 (India); Srinivas, R. [National Centre for Mass Spectrometry, Indian Institute of Chemical Technology (IICT), Hyderabad 500 007 (India); Shyam Sunder, R. [Faculty of Pharmacy, Osmania University, Hyderabad 500 007 (India); Sistla, Ramakrishna, E-mail: sistla@iict.res.in [Medicinal Chemistry and Pharmacology Division, Indian Institute of Chemical Technology (IICT), Hyderabad 500 007 (India)

    2014-05-15

    Gentamicin-induced nephrotoxicity has been well documented, although its underlying mechanisms and preventive strategies remain to be investigated. The present study was designed to investigate the protective effect of naringin, a bioflavonoid, on gentamicin-induced nephrotoxicity and to elucidate the potential mechanism. Serum specific renal function parameters (blood urea nitrogen and creatinine) and histopathology of kidney tissues were evaluated to assess the gentamicin-induced nephrotoxicity. Renal oxidative stress (lipid peroxidation, protein carbonylation, enzymatic and non-enzymatic antioxidants), inflammatory (NF-kB [p65], TNF-α, IL-6 and MPO) and apoptotic (caspase 3, caspase 9, Bax, Bcl-2, p53 and DNA fragmentation) markers were also evaluated. Significant decrease in mitochondrial NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and mitochondrial redox activity indicated the gentamicin-induced mitochondrial dysfunction. Naringin (100 mg/kg) treatment along with gentamicin restored the mitochondrial function and increased the renal endogenous antioxidant status. Gentamicin induced increased renal inflammatory cytokines (TNF-α and IL-6), nuclear protein expression of NF-κB (p65) and NF-κB-DNA binding activity and myeloperoxidase (MPO) activity were significantly decreased upon naringin treatment. In addition, naringin treatment significantly decreased the amount of cleaved caspase 3, Bax, and p53 protein expression and increased the Bcl-2 protein expression. Naringin treatment also ameliorated the extent of histologic injury and reduced inflammatory infiltration in renal tubules. U-HPLS-MS data revealed that naringin co-administration along with gentamicin did not alter the renal uptake and/or accumulation of gentamicin in kidney tissues. These findings suggest that naringin treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress, mitochondrial dysfunction, inflammation and apoptosis in

  13. Insulin adsorption on crystalline SiO2: Comparison between polar and nonpolar surfaces using accelerated molecular-dynamics simulations

    Science.gov (United States)

    Nejad, Marjan A.; Mücksch, Christian; Urbassek, Herbert M.

    2017-02-01

    Adsorption of insulin on polar and nonpolar surfaces of crystalline SiO2 (cristobalite and α -quartz) is studied using molecular dynamics simulation. Acceleration techniques are used in order to sample adsorption phase space efficiently and to identify realistic adsorption conformations. We find major differences between the polar and nonpolar surfaces. Electrostatic interactions govern the adsorption on polar surfaces and can be described by the alignment of the protein dipole with the surface dipole; hence spreading of the protein on the surface is irrelevant. On nonpolar surfaces, on the other hand, van-der-Waals interaction dominates, inducing surface spreading of the protein.

  14. Efficacy of liposomal gentamicin against Rhodococcus equi in a mouse infection model and colocalization with R. equi in equine alveolar macrophages.

    Science.gov (United States)

    Burton, Alexandra J; Giguère, Steeve; Berghaus, Londa J; Hondalus, Mary K; Arnold, Robert D

    2015-04-17

    Rhodococcus equi, a facultative intracellular pathogen and an important cause of pneumonia in foals, is highly susceptible to killing by gentamicin in vitro. However, gentamicin is not effective in vivo, due to its poor cellular penetration. Encapsulation of drugs in liposomes enhances cellular uptake. The objectives of this study were to compare liposomal gentamicin and free gentamicin with respect to their uptake by equine macrophages and intracellular colocalization with R. equi and to compare the efficacies of liposomal gentamicin, free gentamicin and clarithromycin with rifampin for the reduction of R. equi CFU in a mouse model of infection. After ex vivo exposure, a significantly higher mean (±SD) percentage of equine alveolar macrophages contained liposomal gentamicin (91.9±7.6%) as opposed to free gentamicin (16.8±12.5%). Intracellular colocalization of drug and R. equi, as assessed by confocal microscopy, occurred in a significantly higher proportion of cells exposed to liposomal gentamicin (81.2±17.8%) compared to those exposed to free gentamicin (10.4±8.7%). The number of R. equi CFU in the spleen was significantly lower in mice treated with liposomal gentamicin compared to that of mice treated with free gentamicin or to untreated control mice. Treatment with liposomal gentamicin also resulted in a significantly greater reduction in the number of R. equi CFU in the liver compared to treatment with clarithromycin in combination with rifampin. These results support further investigation of liposomal gentamicin as a new treatment for infections caused by R. equi. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Quantum theory of interfacial tension quantitatively predicts spontaneous charging of nonpolar aqueous interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Fernández, Ariel, E-mail: ariel@afinnovation.com [Argentine Institute of Mathematics (I. A. M.), National Research Council (CONICET), Buenos Aires 1083 (Argentina); Collegium Basilea – Institute for Advanced Study, Basel CH4053 (Switzerland)

    2015-10-16

    The spontaneous negative charging of aqueous nonpolar interfaces has eluded quantitative first-principle prediction, possibly because it steadfastly challenges the classical Debye dielectric picture. In this work we show that quantitative prediction requires a substantive revision of Debye's linear dielectric ansatz to incorporate an anomalous polarization component yielding electrostatic energy stored as interfacial tension and detailed enough to account for the differences in electronic structure between water and its ionized states. The minimization of this interfacial tension is due to a quantum effect resulting in the reduction in hydrogen-bond frustration that takes place upon hydroxide ion adsorption. The quantitative predictions are validated vis-à-vis measurements of the free energy change associated with hydroxide adsorption obtained using sum-frequency vibrational spectroscopy. - Highlights: • Spontaneous charging of aqueous nonpolar interfaces challenges Debye dielectrics. • A quantum non-Debye theory of interfacial tension is developed. • The minimization of the interfacial tension promotes hydroxide ion adsorption.

  16. A Simple Method for Estimation of Dielectric Constants and Polarizabilities of Nonpolar and Slightly Polar Hydrocarbons

    Science.gov (United States)

    Panuganti, Sai R.; Wang, Fei; Chapman, Walter G.; Vargas, Francisco M.

    2016-07-01

    Many of the liquids that are used as electrical insulators are nonpolar or slightly polar petroleum-derived hydrocarbons, such as the ones used for cable and/or transformer oils. In this work, semi-empirical expressions with no adjustable parameters for the dielectric constant and the polarizability of nonpolar and slightly polar hydrocarbons and their mixtures are proposed and validated. The expressions that were derived using the Vargas-Chapman One-Third rule require the mass density and the molecular weight of the substance of interest. The equations were successfully tested for various hydrocarbons and polymers with dipole moments eliminate the need of extensive experimental data and require less input parameters compared to existing correlations.

  17. Influence of oxygen in architecting large scale nonpolar GaN nanowires

    CERN Document Server

    Patsha, Avinash; Pandian, Ramanathaswamy; Dhara, S

    2015-01-01

    Manipulation of surface architecture of semiconducting nanowires with a control in surface polarity is one of the important objectives for nanowire based electronic and optoelectronic devices for commercialization. We report the growth of exceptionally high structural and optical quality nonpolar GaN nanowires with controlled and uniform surface morphology and size distribution, for large scale production. The role of O contamination (~1-10^5 ppm) in the surface architecture of these nanowires is investigated with the possible mechanism involved. Nonpolar GaN nanowires grown in O rich condition show the inhomogeneous surface morphologies and sizes (50 - 150 nm) while nanowires are having precise sizes of 40(5) nm and uniform surface morphology, for the samples grown in O reduced condition. Relative O contents are estimated using electron energy loss spectroscopy studies. Size-selective growth of uniform nanowires is also demonstrated, in the O reduced condition, using different catalyst sizes. Photoluminescen...

  18. Vertical nonpolar growth templates for light emitting diodes formed with GaN nanosheets

    Science.gov (United States)

    Yeh, Ting-Wei; Lin, Yen-Ting; Ahn, Byungmin; Stewart, Lawrence S.; Daniel Dapkus, P.; Nutt, Steven R.

    2012-01-01

    We demonstrate that nonpolar m-plane surfaces can be generated on uniform GaN nanosheet arrays grown vertically from the (0001)-GaN bulk material. InGaN/GaN multiple quantum wells (MQWs) grown on the facets of these nanosheets are demonstrated by cross-sectional transmission electron microscopy. Owing to the high aspect ratio of the GaN nanosheet structure, the MQWs predominantly grow on nonpolar GaN planes. The results suggest that GaN nanosheets provide a conduction path for device fabrication and also a growth template to reduce the piezoelectric field inside the active region of InGaN-based light emitting diodes.

  19. Electrokinetics of Polar Liquids in Contact with Non-Polar Surfaces

    CERN Document Server

    Lin, Chih-Hsiu; Chaudhury, Manoj K

    2014-01-01

    Zeta potentials of several polar protic (water, ethylene glycol, formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three non-polar surfaces using closed-cell electro-osmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the non-polar surfaces with these observations: the electrokinetic effect on the fluorocarbon-coated surface is the strongest; and on a PDMS grafted surface, the effect is the weakest. Even though these hygroscopic liquids contain small amounts of water, the current models of charging based on the adsorption of hydroxide ions at the interface or the dissociation of preexisting functionalities (e.g., silanol groups) appear to be insufficient to account for the various facets of the experimental observations. The results illustrate how ubiquitous the phenomenon of electro-kinetics ...

  20. Stable and efficient colour enrichment powders of nonpolar nanocrystals in LiCl

    Science.gov (United States)

    Erdem, Talha; Soran-Erdem, Zeliha; Sharma, Vijay Kumar; Kelestemur, Yusuf; Adam, Marcus; Gaponik, Nikolai; Demir, Hilmi Volkan

    2015-10-01

    In this work, we propose and develop the inorganic salt encapsulation of semiconductor nanocrystal (NC) dispersion in a nonpolar phase to make a highly stable and highly efficient colour converting powder for colour enrichment in light-emitting diode backlighting. Here the wrapping of the as-synthesized green-emitting CdSe/CdZnSeS/ZnS nanocrystals into a salt matrix without ligand exchange is uniquely enabled by using a LiCl ionic host dissolved in tetrahydrofuran (THF), which simultaneously disperses these nonpolar nanocrystals. We studied the emission stability of the solid films prepared using NCs with and without LiCl encapsulation on blue LEDs driven at high current levels. The encapsulated NC powder in epoxy preserved 95.5% of the initial emission intensity and stabilized at this level while the emission intensity of NCs without salt encapsulation continuously decreased to 34.7% of its initial value after 96 h of operation. In addition, we investigated the effect of ionic salt encapsulation on the quantum efficiency of nonpolar NCs and found the quantum efficiency of the NCs-in-LiCl to be 75.1% while that of the NCs in dispersion was 73.0% and that in a film without LiCl encapsulation was 67.9%. We believe that such ionic salt encapsulated powders of nonpolar NCs presented here will find ubiquitous use for colour enrichment in display backlighting.In this work, we propose and develop the inorganic salt encapsulation of semiconductor nanocrystal (NC) dispersion in a nonpolar phase to make a highly stable and highly efficient colour converting powder for colour enrichment in light-emitting diode backlighting. Here the wrapping of the as-synthesized green-emitting CdSe/CdZnSeS/ZnS nanocrystals into a salt matrix without ligand exchange is uniquely enabled by using a LiCl ionic host dissolved in tetrahydrofuran (THF), which simultaneously disperses these nonpolar nanocrystals. We studied the emission stability of the solid films prepared using NCs with and

  1. Broadband non-polarizing terahertz beam splitters with variable split ratio

    KAUST Repository

    Wei, Minggui

    2017-08-15

    Seeking effective terahertz functional devices has always aroused extensive attention. Of particular interest is the terahertz beam splitter. Here, we have proposed, designed, manufactured, and tested a broadband non-polarizing terahertz beam splitter with a variable split ratio based on an all-dielectric metasurface. The metasurface was created by patterning a dielectric surface of the N-step phase gradient and etching to a few hundred micrometers. The conversion efficiency as high as 81% under the normal incidence at 0.7 THz was achieved. Meanwhile, such a splitter works well over a broad frequency range. The split ratio of the proposed design can be continuously tuned by simply shifting the metasurface, and the angle of emergences can also be easily adjusted by choosing the step of phase gradients. The proposed design is non-polarizing, and its performance is kept under different polarizations.

  2. Non-polar Solvent Microwave-Assisted Extraction of Volatile Constituents from Dried Zingiber Officinale Rosc.

    Institute of Scientific and Technical Information of China (English)

    YU Yong; WANG Zi-Ming; WANG Yu-Tang; LI Tie-Chun; CHENG Jian-Hua; LIU Zhong-Ying; ZHANG Han-Qi

    2007-01-01

    A new method, non-polar solvent microwave-assisted extraction (NPSMAE), was applied to the extraction of essential oil from Zingiber officinale Rosc. in closed-vessel system. By adding microwave absorption mediumcarbonyl iron powders (CIP) into extraction system, the essential oil was extracted by the non-polar solvent (ether)which can be heated by CIP. The constituents of essential oil obtained by NPSMAE were comparable with those obtained by hydrodistillation (HD) by GC-MS analysis, which indicates that NPSMAE is a feasible way to extract essential oil from dried plant materials. The NPSMAE took much less extraction time (5 min) than HD (180 min),and its extraction efficiency was much higher than that of conventional polar solvent microwave-assisted extraction (PSMAE) and mixed solvent microwave-assisted extraction (MSMAE). It can be a good alternative for the extraction of volatile constituents from dried plant samples.

  3. Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions.

    Science.gov (United States)

    Ballal, Deepti; Venkataraman, Pradeep; Fouad, Wael A; Cox, Kenneth R; Chapman, Walter G

    2014-08-14

    Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ε(W)/k = 220 K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E-ε(W)/k = 78.2 K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally.

  4. A comparative DFT study of the structural and electronic properties of nonpolar GaN surfaces

    Energy Technology Data Exchange (ETDEWEB)

    González-Hernández, Rafael, E-mail: rhernandezj@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); González-García, Alvaro [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Barragán-Yani, Daniel [Fachgebiet Material modellierung, Institut für Materialwissenschaft, Technische Universität Darmstadt, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); López-Pérez, William [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia)

    2014-09-30

    Highlights: • A comparative analysis of the geometry and the electronic characteristics of nonpolar GaN surfaces was carried out. • Surface energies are too low for LDA, but lower still for GGA and MGGA functionals, except for PBEsol. • PBEsol exhibits good lattice parameters and surface energies. • Surface intra-gap states reduce the band gap of the nonpolar GaN surfaces. • Slight changes in the dispersion of surface states were observed for the LDA, GGA, and MGGA functionals. - Abstract: A comparative analysis of the geometry and the electronic characteristics of nonpolar GaN surfaces was carried out using density-functional theory (DFT) with different approximations for the exchange-correlation energy (LDA, PBE, PBEsol, RPBE, TPSS, revTPSS, and HSE). The obtained data show that the GaN(101{sup ¯}0) (m-plane) is more energetically stable than the GaN(112{sup ¯}0) (a-plane) surface. However, these surfaces have similar surface relaxation geometry, with a Ga-N surface bond-length contraction of around 6–7% and a Ga-N surface rotational angle in the range of 6–9°. Our results show that the use of different exchange-correlation functionals does not significantly change the surface energy and surface geometry. In addition, we found the presence of surface intra-gap states that reduce the band gap of the nonpolar GaN surface with respect to the bulk value, in agreement with recent photoelectron and surface optical spectroscopy experiments.

  5. Contact angles and wettability of ionic liquids on polar and non-polar surfaces.

    Science.gov (United States)

    Pereira, Matheus M; Kurnia, Kiki A; Sousa, Filipa L; Silva, Nuno J O; Lopes-da-Silva, José A; Coutinho, João A P; Freire, Mara G

    2015-12-21

    Many applications involving ionic liquids (ILs) require the knowledge of their interfacial behaviour, such as wettability and adhesion. In this context, herein, two approaches were combined aiming at understanding the impact of the IL chemical structures on their wettability on both polar and non-polar surfaces, namely: (i) the experimental determination of the contact angles of a broad range of ILs (covering a wide number of anions of variable polarity, cations, and cation alkyl side chain lengths) on polar and non-polar solid substrates (glass, Al-plate, and poly-(tetrafluoroethylene) (PTFE)); and (ii) the correlation of the experimental contact angles with the cation-anion pair interaction energies generated by the Conductor-like Screening Model for Real Solvents (COSMO-RS). The combined results reveal that the hydrogen-bond basicity of ILs, and thus the IL anion, plays a major role through their wettability on both polar and non-polar surfaces. The increase of the IL hydrogen-bond accepting ability leads to an improved wettability of more polar surfaces (lower contact angles) while the opposite trend is observed on non-polar surfaces. The cation nature and alkyl side chain lengths have however a smaller impact on the wetting ability of ILs. Linear correlations were found between the experimental contact angles and the cation-anion hydrogen-bonding and cation ring energies, estimated using COSMO-RS, suggesting that these features primarily control the wetting ability of ILs. Furthermore, two-descriptor correlations are proposed here to predict the contact angles of a wide variety of ILs on glass, Al-plate, and PTFE surfaces. A new extended list is provided for the contact angles of ILs on three surfaces, which can be used as a priori information to choose appropriate ILs before a given application.

  6. Contact angles and wettability of ionic liquids on polar and non-polar surfaces†

    Science.gov (United States)

    Sousa, Filipa L.; Silva, Nuno J. O.; Lopes-da-Silva, José A.; Coutinho, João A. P.; Freire, Mara G.

    2016-01-01

    Many applications involving ionic liquids (ILs) require the knowledge of their interfacial behaviour, such as wettability and adhesion. In this context, herein, two approaches were combined aiming at understanding the impact of the IL chemical structures on their wettability on both polar and non-polar surfaces, namely: (i) the experimental determination of the contact angles of a broad range of ILs (covering a wide number of anions of variable polarity, cations, and cation alkyl side chain lengths) on polar and non-polar solid substrates (glass, Al-plate, and poly-(tetrafluoroethylene) (PTFE)); and (ii) the correlation of the experimental contact angles with the cation–anion pair interaction energies generated by the Conductor-like Screening Model for Real Solvents (COSMO-RS). The combined results reveal that the hydrogen-bond basicity of ILs, and thus the IL anion, plays a major role through their wettability on both polar and non-polar surfaces. The increase of the IL hydrogen-bond accepting ability leads to an improved wettability of more polar surfaces (lower contact angles) while the opposite trend is observed on non-polar surfaces. The cation nature and alkyl side chain lengths have however a smaller impact on the wetting ability of ILs. Linear correlations were found between the experimental contact angles and the cation–anion hydrogen-bonding and cation ring energies, estimated using COSMO-RS, suggesting that these features primarily control the wetting ability of ILs. Furthermore, two-descriptor correlations are proposed here to predict the contact angles of a wide variety of ILs on glass, Al-plate, and PTFE surfaces. A new extended list is provided for the contact angles of ILs on three surfaces, which can be used as a priori information to choose appropriate ILs before a given application. PMID:26554705

  7. Modeling diffusion coefficients in binary mixtures of polar and non-polar compounds

    DEFF Research Database (Denmark)

    Medvedev, Oleg; Shapiro, Alexander

    2005-01-01

    The theory of transport coefficients in liquids, developed previously, is tested on a description of the diffusion coefficients in binary polar/non-polar mixtures, by applying advanced thermodynamic models. Comparison to a large set of experimental data shows good performance of the model. Only...... components and to only one parameter for mixtures consisting of non-polar components. A possibility of complete prediction of the parameters is discussed....

  8. Hydrophobic monolayered nanoflakes of tungsten oxide: coupled exfoliation and fracture in a nonpolar organic medium.

    Science.gov (United States)

    Honda, Masashi; Oaki, Yuya; Imai, Hiroaki

    2015-06-21

    Coupled exfoliation and fracture induced formation of hydrophobic monolayered nanoflakes in a nonpolar organic medium. The hydrophobic monolayered nanoflakes 5-20 nm in lateral size consisted of a tungstate layer with surface modification by stearylammonium ions (C18H37NH3)0.397 H0.603Cs3W11O35·xH2O (x < 0.625).

  9. Electric Charge Accumulation in Polar and Non-Polar Polymers under Electron Beam Irradiation

    Science.gov (United States)

    Nagasawa, Kenichiro; Honjoh, Masato; Takada, Tatsuo; Miyake, Hiroaki; Tanaka, Yasuhiro

    The electric charge accumulation under an electron beam irradiation (40 keV and 60 keV) was measured by using the pressure wave propagation (PWP) method in the dielectric insulation materials, such as polar polymeric films (polycarbonate (PC), polyethylene-naphthalate (PEN), polyimide (PI), and polyethylene-terephthalate (PET)) and non-polar polymeric films (polystyrene (PS), polypropylene (PP), polyethylene (PE) and polytetrafluoroethylene (PTFE)). The PE and PTFE (non-polar polymers) showed the properties of large amount of electric charge accumulation over 50 C/m3 and long saturation time over 80 minutes. The PP and PS (non-polar polymer) showed the properties of middle amount of charge accumulation about 20 C/m3 and middle saturation time about 1 to 20 minutes. The PC, PEN, PI and PET (polar polymers) showed the properties of small amount of charge accumulation about 5 to 20 C/m3 and within short saturation time about 1.0 minutes. This paper summarizes the relationship between the properties of charge accumulation and chemical structural formula, and compares between the electro static potential distribution with negative charged polymer and its chemical structural formula.

  10. Enhanced UV detection by non-polar epitaxial GaN films

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Shruti; Chandan, Greeshma; Mohan, Lokesh; Krupanidhi, S. B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore (India); Central Research Laboratory, Bharat Electronics, Bangalore (India); Shetty, Arjun [Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore (India)

    2015-12-15

    Nonpolar a-GaN (11-20) epilayers were grown on r-plane (1-102) sapphire substrates using plasma assisted molecular beam epitaxy. High resolution x-ray diffractometer confirmed the orientation of the grown film. Effect of the Ga/N ratio on the morphology and strain of a-GaN epilayers was compared and the best condition was obtained for the nitrogen flow of 1 sccm. Atomic force microscopy was used to analyze the surface morphology while the strain in the film was quantitatively measured using Raman spectroscopy and qualitatively analyzed by reciprocal space mapping technique. UV photo response of a-GaN film was measured after fabricating a metal-semiconductor-metal structure over the film with gold metal. The external quantum efficiency of the photodetectors fabricated in the (0002) polar and (11-20) nonpolar growth directions were compared in terms of responsivity and nonpolar GaN showed the best sensitivity at the cost of comparatively slow response time.

  11. Chemical etching behaviors of semipolar (11̄22) and nonpolar (11̄20) gallium nitride films.

    Science.gov (United States)

    Jung, Younghun; Baik, Kwang Hyeon; Mastro, Michael A; Hite, Jennifer K; Eddy, Charles R; Kim, Jihyun

    2014-08-14

    Wet chemical etching using hot KOH and H3PO4 solutions was performed on semipolar (11̄22) and nonpolar (11̄20) GaN films grown on sapphire substrates. An alternating KOH/H3PO4/KOH etch process was developed to control the orientation of the facets on the thin-film surface. The initial etch step in KOH produced c- and m-plane facets on the surface of both semipolar (11̄22) and nonpolar (11̄20) GaN thin-films. A second etch step in H3PO4 solution additionally exposed a (̄1̄12̄2) plane, which is chemically stable in H3PO4 solution. By repeating the chemical etch with KOH solution, the m-plane facets as seen in the original KOH etch step were recovered. The etching methods developed in our work can be used to control the surface morphologies of nonpolar and semipolar GaN-based optoelectronic devices such as light-emitting diodes and solar cells.

  12. Enhanced sensing of nonpolar volatile organic compounds by silicon nanowire field effect transistors.

    Science.gov (United States)

    Paska, Yair; Stelzner, Thomas; Christiansen, Silke; Haick, Hossam

    2011-07-26

    Silicon nanowire field effect transistors (Si NW FETs) are emerging as powerful sensors for direct detection of biological and chemical species. However, the low sensitivity of the Si NW FET sensors toward nonpolar volatile organic compounds (VOCs) is problematic for many applications. In this study, we show that modifying Si NW FETs with a silane monolayer having a low fraction of Si-O-Si bonds between the adjacent molecules greatly enhances the sensitivity toward nonpolar VOCs. This can be explained in terms of an indirect sensor-VOC interaction, whereby the nonpolar VOC molecules induce conformational changes in the organic monolayer, affecting (i) the dielectric constant and/or effective dipole moment of the organic monolayer and/or (ii) the density of charged surface states at the SiO(2)/monolayer interface. In contrast, polar VOCs are sensed directly via VOC-induced changes in the Si NW charge carriers, most probably due to electrostatic interaction between the Si NW and polar VOCs. A semiempirical model for the VOC-induced conductivity changes in the Si NW FETs is presented and discussed.

  13. Measurement and Modeling of Carbon Dioxide Solubility in Polar and Nonpolar Solvent

    Directory of Open Access Journals (Sweden)

    Hojatollah Ahmadi

    2012-08-01

    Full Text Available The solubility of gases is an important issue in the industries. Carbon Dioxide Through gas transmission line exists as sour gas therefore it is eliminated by solvent in industry. Carbone Dioxide is nonpolar molecule that has lower solubility in liquid solvent. In this study the solubility of carbon dioxide in some polar and nonpolar solvents (include Acetone, Acetic Acid, Benzene, Carbon Tetra Chloride, Chlorobenzene, Chloroform, Cyclo-hexane, Di-Methyl Formamid, Ethanol, Ethyl acetate, Methanol, NButanol, N-Heptane, N-Hexane at atmospheric pressure and temperatures range from 5-35ºC was determined. A laboratory unit was made for this experience and the solubility of CO2 was reported. The solubility of carbon dioxide in these solvent was low due to unreactivity and nonpolarity nature of these material. The solubility of CO2 in Ethyl Acetate and Methanol was highest and lowest respectively. This investigation showed that the solvent with carbonyl group have higher activity than other.

  14. Tritium Labeled Gentamicin C: II.- Bioradiactive Degradation Products of Gentamicin by Catalytic H2O-3H Exchange Reaction; Getamicina C Tritiada: II.- Productos de Degradacion Radiactivos y Bioactivos en el Intercambio Catalitico con H2O-3H

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, C.; Diaz, A.; Paz, D.; Jimeno, M. L.

    1992-07-01

    The main bio radioactive degradation products from catalytic hydrogen exchange of gentamicin C, (C1 + C2 + Cla) in basic form, are generated by N-demethylation in 3{sup -}N and 6-N positions. Their structures were confirmed by 1HNMR and 13CNMR. These derivatives were fractionated by chromatography on silica gel. Antibacterial activities were similar to those of the parent antibiotics. Tritium exchange, under vacuum or nitrogen, is highly increased (4:1) when gentamicin are in basic form. In contrast with gentamicin sulfate, hydrolytic sub products as gramine, genta mines, garosamine and purpurosamines are practically absent. To properly optimize the exchange process, the composition of the gentamicin C complex must be taken into account. The exchange decreases in the order C2 > C1> Cla. Because of 6'-N-demethyl gentamicin C1 is C2, the radiochemical yield of C2 appears enhanced in the H2O-3H exchange of a mixture of them. Radioactivity distribution among the components and subunits of these three gentamicin were studied by strong and mild hydrolysis, and by methanolysis. (Author) 18 refs.

  15. Nephro-protective effect of vitamin C and Nigella sativa oil on gentamicin associated nephrotoxicity in rabbits

    National Research Council Canada - National Science Library

    Saleem, Uzma; Ahmad, Bashir; Rehman, Kanwal; Mahmood, Saeed; Alam, Maqsood; Erum, Alia

    2012-01-01

    .... An aminoglycoside, gentamicin, has pronounced nephrotoxic effect in humans and animals and this study was planned to observe the nephro-protective effect of antioxidants, vitamin C and Nigella sativa oil...

  16. Impact of clinical decision support guidelines on therapeutic drug monitoring of gentamicin in newborns.

    Science.gov (United States)

    Fonzo-Christe, Caroline; Guignard, Bertrand; Zaugg, Claudia; Coehlo, Ana; Posfay-Barbe, Klara M; Gervaix, Alain; Desmeules, Jules; Rollason, Victoria; Combescure, Christophe; Corbelli, Regula; Rimensberger, Peter; Pfister, Riccardo; Bonnabry, Pascal

    2014-10-01

    Our institution's gentamicin dosing and therapeutic drug monitoring (TDM) practices for newborns were suspected to be very heterogeneous. Once-daily dosing (ODD) or extended-interval dosing (EID) and trough concentration measurement were recommended. Clinical decision support guidelines were developed and implemented as clinical decision support in the computerized prescriber order entry system. Impact on dosing, TDM practices, and blood sampling were evaluated. A 1-year retrospective historically controlled study before (April 2008-March 2009) and after the implementation of guidelines (January 2010-December 2010) for newborns ( 0.05). After implementation of the guidelines, an ODD/EID regimen was almost exclusively used (97.7% versus 61.6%, P Guideline implementation generated a sharp reduction in blood sampling. Clinical benefits of better gentamicin dosing and TDM practices were evident. Cost-effectiveness and clinical benefit of reduced blood sampling should be evaluated.

  17. Nitric oxide in guinea pig vestibular sensory cells following gentamicin exposure in vitro.

    Science.gov (United States)

    Takumida, M; Anniko, M

    2001-04-01

    Gentamicin-induced production of nitric oxide (NO) in the vestibular end organs of the guinea pig was investigated using the new fluorescence indicator 4,5-diaminofluorescein diacetate for direct detection of NO. Utricular maculae and isolated vestibular sensory cells were examined to locate NO production sites. The fluorescence intensity of the sensory cells was augmented by stimulation with gentamicin. This increase in fluorescence was inhibited by the presence of the non-specific inhibitor for nitric oxide synthase, L-N(G)-nitroarginine methylester, and by the non-specific N-methyl-D-aspartic acid antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate. These findings indicate that NO may play an important role in the ototoxicity of aminoglycoside.

  18. Naringin ameliorates gentamicin-induced nephrotoxicity and associated mitochondrial dysfunction, apoptosis and inflammation in rats: possible mechanism of nephroprotection.

    Science.gov (United States)

    Sahu, Bidya Dhar; Tatireddy, Srujana; Koneru, Meghana; Borkar, Roshan M; Kumar, Jerald Mahesh; Kuncha, Madhusudana; Srinivas, R; Shyam Sunder, R; Sistla, Ramakrishna

    2014-05-15

    Gentamicin-induced nephrotoxicity has been well documented, although its underlying mechanisms and preventive strategies remain to be investigated. The present study was designed to investigate the protective effect of naringin, a bioflavonoid, on gentamicin-induced nephrotoxicity and to elucidate the potential mechanism. Serum specific renal function parameters (blood urea nitrogen and creatinine) and histopathology of kidney tissues were evaluated to assess the gentamicin-induced nephrotoxicity. Renal oxidative stress (lipid peroxidation, protein carbonylation, enzymatic and non-enzymatic antioxidants), inflammatory (NF-kB [p65], TNF-α, IL-6 and MPO) and apoptotic (caspase 3, caspase 9, Bax, Bcl-2, p53 and DNA fragmentation) markers were also evaluated. Significant decrease in mitochondrial NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and mitochondrial redox activity indicated the gentamicin-induced mitochondrial dysfunction. Naringin (100mg/kg) treatment along with gentamicin restored the mitochondrial function and increased the renal endogenous antioxidant status. Gentamicin induced increased renal inflammatory cytokines (TNF-α and IL-6), nuclear protein expression of NF-κB (p65) and NF-κB-DNA binding activity and myeloperoxidase (MPO) activity were significantly decreased upon naringin treatment. In addition, naringin treatment significantly decreased the amount of cleaved caspase 3, Bax, and p53 protein expression and increased the Bcl-2 protein expression. Naringin treatment also ameliorated the extent of histologic injury and reduced inflammatory infiltration in renal tubules. U-HPLS-MS data revealed that naringin co-administration along with gentamicin did not alter the renal uptake and/or accumulation of gentamicin in kidney tissues. These findings suggest that naringin treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress, mitochondrial dysfunction, inflammation and apoptosis in

  19. Effect of uric acid on gentamicin-induced nephrotoxicity in rats - role of matrix metalloproteinases 2 and 9.

    Science.gov (United States)

    Romero, Freddy; Pérez, Mariela; Chávez, Maribel; Parra, Gustavo; Durante, Paula

    2009-12-01

    In this work, we aimed to study the effect of uric acid on gentamicin-induced nephrotoxicity. Male Sprague-Dawley rats were assigned to one of six groups (six rats each) which received intraperitoneal injections for 9 days: (S) saline; (UA) Uric acid alone; (G) Gentamicin alone; (G + UA) Gentamicin + uric acid; (G rec) Gentamicin recovery and (G + UA rec) Gentamicin + uric acid recovery. In (G rec) and (G + UA rec), rats recovered for 7 days after the last injection. Urine and blood samples were taken on day 0 and at the end of every stage. Kidneys were harvested for histological scoring, determination of renal malondialdehyde (MDA), zymography and western blots for matrix metalloprotease (MMP)-2 and MMP-9. Uric acid alone did not provoke changes in biochemical and histological parameters when compared to controls. Gentamicin alone increased significantly plasma creatinine and blood urea nitrogen and caused a moderate histological damage. When combined with uric acid, these conditions worsened. MMP-9 activity and expression was decreased in rats from group G + UA as compared with rats from group G, while activity of MMP-2 was similarly increased in both groups when compared to controls. The increase in renal MDA induced by gentamicin was not altered when it was combined with uric acid. During the recovery stage, all biochemical parameters returned to normal levels, though a trend for delay of tubular damage recovery was observed in group G + UA rec when compared with group G rec. The results indicate that uric acid worsens gentamicin-induced nephrotoxicity. The mechanism is likely to implicate down-regulation of MMP-9.

  20. Histological Evidence of Nephroprotective Effect of Ashwagandha (Withania somnifera Root Extract against Gentamicin Induced Nephrotoxicity in Rats

    Directory of Open Access Journals (Sweden)

    Sadia Choudhury Shimmi

    2014-01-01

    Full Text Available Background: Kidney damage can occur due to exposure to nephrotoxic drugs, chemicals, toxins and infectious agents, ultimately leading to renal failure, management of which is a great challenge. So, efforts have been focused on traditional and herbal medicines for the treatment of renal failure. Ashwagandha (Withania somnifera may have free radical scavenging activity and can be used for the prevention and treatment of kidney damage. Objective: To observe the histological evidence of nephroprotective effect of Ashwagandha root against gentamicin induced nephrotoxicity in rats. Materials and Methods: This study was done in the department of Physiology, Sir Salimullah Medical College, Dhaka. A total number of 31 male Wistar albino rats were acclimatized for 14 days. Then, these were divided into two groups, control group consisted of 18 rats (Group A and Ashwagandha pretreated and gentamicin-treated group consisted of 13 rats (Group B. Control group was again subdivided into baseline control and gentamicin-treated control groups (A1 and A2 ─ each group contained 9 rats. All the animals received basal diet for 22 consecutive days. In addition to this, animals of Group A2 received gentamicin subcutaneously (100 mg/kg body weight/day from 15th to 22nd day and animals of Group B received Ashwagandha root extract (500 mg/kg body weight/day orally for 22 consecutive days and gentamicin subcutaneously (100 mg/kg body weight/day from 15th to 22nd day. All the animals were sacrificed on 23rd day. Then kidney samples were collected and histology was done by using standard laboratory procedure. Results: Histological examination of kidney revealed abnormal histological findings in 100% of gentamicin-treated rats. But 92.31% of rats in Ashwagandha pretreated and gentamicin-treated group showed almost normal structure and 7.69% showed mild histological changes. Conclusion: Ashwagandha root may have some nephroprotective effect against gentamicin induced

  1. Novel Pathways for Ameliorating the Fitness Cost of Gentamicin Resistant Small Colony Variants

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Paulander, Wilhelm; Leng, Bingfeng;

    2016-01-01

    Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby li...

  2. Leishmanicidal Activity of Films Containing Paromomycin and Gentamicin Sulfate both In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    SH Hejazi

    2011-09-01

    Full Text Available Background: Based on the efficacy of paromomycin ointment and recent ongoing clinical trials of combination of paromomycin and gentamicin, a new physical form of films of the paromomy­cin and gentamicin was prepared and anti-Leishmania activities of the prepared films were as­sessed in vitro and in vivo.Methods: Paromomycin 15% and gentamicin 0.5% was incorporated in a film using ethyl cellu­lose and HPMC (Hydroxyl Propyl Methyl Cellulose. In order to assess the drug release and anti-Leishmania activities of the preparation, a clone L. major parasite was established using a set of modified NNN medium without overlay liquid layer. Therapeutic effects of the films were evalu­ated using Balb/c mice model. The mice were inoculated with 2×106 L. major promastigotes (MRHO/IR/75/ER and then when the lesions developed the mice were randomly divided in 3 groups, 10 mice per group, and treated with either perpetrated films or placebo for 28 days or left untreated.Results: Growth inhibition of cloned promastigotes showed that the films have enough releasing capacity and in vivo system, the films containing paromomycin and gentamicin was able to re­duce the lesion size and induced complete cure in 80% of the mice but relapse was seen in 60% of the cured mice and overall 50% cure rate was seen during 20 weeks period of the study.Conclusion: It seems that the prepared films might be further used in human clinical trials.

  3. Controlled gentamicin release from multi-layered electrospun nanofibrous structures of various thicknesses

    Directory of Open Access Journals (Sweden)

    Sirc J

    2012-10-01

    Full Text Available Jakub Sirc,1 Sarka Kubinova,2 Radka Hobzova,1 Denisa Stranska,3 Petr Kozlik,4 Zuzana Bosakova,4 Dana Marekova,2 Vladimir Holan,5 Eva Sykova,2 Jiri Michalek11Department of Polymer Gels, Institute of Macromolecular Chemistry, Academy of Science of the Czech Republic, Prague, Czech Republic; 2Department of Neuroscience, Institute of Experimental Medicine, Academy of Science of the Czech Republic, Prague, Czech Republic; 3Elmarco Ltd, Liberec, Czech Republic; 4Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Prague, Czech Republic; 5Department of Transplant Immunology, Institute of Molecular Genetics, Academy of Science of the Czech Republic, Prague, Czech RepublicAbstract: Polyvinyl alcohol nanofibers incorporating the wide spectrum antibiotic gentamicin were prepared by Nanospider™ needleless technology. A polyvinyl alcohol layer, serving as a drug reservoir, was covered from both sides by polyurethane layers of various thicknesses. The multilayered structure of the nanofibers was observed using scanning electron microscopy, the porosity was characterized by mercury porosimetry, and nitrogen adsorption/desorption measurements were used to determine specific surface areas. The stability of the gentamicin released from the electrospun layers was proved by high-performance liquid chromatography (HPLC and inhibition of bacterial growth. Drug release was investigated using in vitro experiments with HPLC/MS quantification, while the antimicrobial efficacy was evaluated on Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. Both experiments proved that the released gentamicin retained its activity and showed that the retention of the drug in the nanofibers was prolonged with the increasing thickness of the covering layers.Keywords: nanofibers, electrospinning, multilayered structure, morphology, gentamicin, drug release

  4. Effect of caraway on gentamicin-induced oxidative stress, inflammation and nephrotoxicity in rats

    Directory of Open Access Journals (Sweden)

    Hoda Erjaee

    2015-07-01

    Full Text Available Different potentially therapeutic approaches to prevent or attenuate gentamicin (GEM induced nephrotoxicity have been proposed. The aim of the present study was to investigate the possible protective effects of caraway seed oil against GEM-induced nephrotoxicity in rats. Rats (24 were randomly assigned into four equal groups: i normal control group, ii treated with GEM, iii pretreated with orally caraway seed oil 10 (mg kg−1 plus GEM and iv treated with GEM and caraway seed oil 10 mg kg−1. Biochemical examinations were utilized for evaluation of the oxidative stress and renal nephrotoxicity. Creatinine, blood urea nitrogen (BUN, plasma malondialdehyde (MDA levels, catalase (CAT, superoxide dismutase (SOD and glutathione peroxidase (GSH-Px activities were determined. Administration of gentamicin to rats induced a marked renal failure, characterized by a significant increase in plasma creatinine and BUN concentrations. The animals treated with gentamicin alone showed a significantly higher plasma MDA level andlower SOD, GSH-Px and CAT activities when compared with the control group. Treatment and simultaneous treatment with caraway seed oil produced amelioration in MDA and increased the activity of antioxidant enzymes SOD, GSH-Px and CAT when compared with the gentamicin treated group. In addition, GEM nephrotoxicity increased renal inflammatory cytokines (TNF-α, IL-6 and IFN-γ. Pro-inflammatory cytokines were significantly decreased (P<0.05 in the test groups administered caraway seed oil. These findings suggest that caraway seed oil treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress and inflammation in rats.

  5. Vestibular results after intratympanic gentamicin therapy in disabling Menière's disease.

    Science.gov (United States)

    Junet, Philippe; Karkas, Alexandre; Dumas, Georges; Quesada, Jean Louis; Schmerber, Sébastien

    2016-10-01

    Intratympanic injection of gentamicin is increasingly used in the treatment of unilateral disabling Menière's disease (MD). Several objective functional and subjective tests have been developed to assess the control of vertigo after gentamicin treatment. The aim of this study was to show that subjective results require a vestibular deafferentation as profound as possible, evidenced with multifrequency vestibular assessment. Sixty four patients with intractable MD in situation of medical treatment failure longer than 6 months were included between 1998 and 2013 in this case control study. A 2-year follow-up was performed after the last intratympanic gentamicin performed with the titration technique. A vestibular assessment was applied before and after 2 years of treatment with a functional level score using the AAOHNS vertigo scale and multifrequency vestibular assessment: skull vibration-induced nystagmus test (SVINT), head-shaking test (HST) and caloric test (CaTe). The correlation between the results of the questionnaire and the level of the deafferentation as evaluated by the tests was analyzed with the Spearman test. Among the 64 included patients, 56 (87.5 %) described vertigo control. There was a correlation (=-0.33 [-0.53; -0.09], p = 0.008) between subjective improvement (AAO -HNS 1 or 2) and the degree of vestibular deafferentation as evidenced by a destructive nystagmus (beating toward the safe side) with the HST and the SVINT, as well as a caloric hypofunction >90 % with the CaTe. The present study demonstrates that a profound vestibular deafferentation confirmed with multifrequency test evaluation is needed to have a subjective improvement in the treatment of unilateral disabling MD with intratympanic gentamicin.

  6. Amylase-creatinine clearance ratio. A simple test to predict gentamicin nephrotoxicity.

    Science.gov (United States)

    Aderka, D; Tene, M; Graff, E; Levo, Y

    1988-05-01

    The initial target of aminoglycoside nephrotoxicity is the proximal tubule. Yet, no simple test is available to predict such toxicity. Taking advantage of the fact that amylase is filtered in the glomerulus and reabsorbed by the proximal tubules, we prospectively examined in 23 patients if changes in renal amylase creatinine clearance ratio (ACCR) can predict gentamicin nephrotoxicity. Eighteen of these patients had an initial creatinine clearance (rCcr) above 30 mL/min. Eleven of them (group A) had an ACCR above 3.5% (control 3% +/- 1.03%) and all exhibited an average reduction of 32.2% +/- 11.6% in rCcr following one week of gentamicin therapy. In contrast, only one of seven patients (group B) with an initial ACCR below 3.5% had a reduction, albeit transient, in rCcr. During gentamicin therapy, group A patients had a further increase in ACCR which was proportional to the reduction observed in rCcr (r = -.54). Our preliminary data suggest that ACCR may prove a simple and possibly a reliable predictor of kidney function deterioration during gentamicin therapy in patients with rCcr above 30 mL/min: patients with pretherapy ACCR above 3.5% may exhibit a deterioration in the creatinine clearance during the first week of therapy. For patients with pretherapy renal failure (rCcr less than 30 mL/min) the creatinine levels (but not the ACCR) seem to retain their significance in predicting and monitoring further renal function deterioration during aminoglycoside therapy.

  7. Effect of Tephrosia purpurea (L.) Pers. Leaves on Gentamicin-Induced Nephrotoxicity in Rats.

    Science.gov (United States)

    Jain, Avijeet; Nahata, Alok; Singhai, Abhay Kumar

    2013-01-01

    The aim of the study was to evaluate the nephroprotective and nephrocurative effects of Tephrosia purpurea (L.) Pers. leaves against gentamicin-induced acute renal injury in albino rats. The maximum free radical scavenging activity of the ethanolic extract was the basis for the selection of this extract for the in vivo study. Gentamicin (40 mg/kg, s.c.) was administered to induce toxicity in the toxic group and the ethanolic extract (200 mg/kg p.o.) was administered in all treated groups. Blood urea and serum creatinine levels were monitored to assess the effects. The antioxidant potential was also evaluated by the estimation of reduced glutathione (GSH) and malondialdehyde (MDA). Gentamicin intoxication caused significant increases in blood urea and serum creatinine levels as compared to the normal control. In the preventive regimen, the extract (200 mg/kg, p.o.) showed significant reductions in the elevated blood urea and serum creatinine. Histopathological changes were in accordance with the biochemical findings. Also in the curative regimen, the blood urea and serum creatinine levels revealed significant curative effects. In our in vivo antioxidant activity, the GSH level was significantly (PTephrosia purpurea leaves possesses marked nephroprotective and curative activities without any toxicity. The proposed mechanisms for the claimed activity are antioxidant activity and the inhibition of an overproduction of NO and Cox-2 expression. These activities may be attributed to the presence of phenolics and flavonoidal compounds like rutin and quercetin. Thus, it can be said that Tephrosia purpurea could offer a promising role in the treatment of acute renal injury caused by nephrotoxins like gentamicin.

  8. Collagen implant with gentamicin sulphate reduces surgical site infection in vascular surgery: a prospective cohort study.

    Science.gov (United States)

    Costa Almeida, Carlos Eduardo Perdigão; Reis, Luis; Carvalho, Luis; Costa Almeida, Carlos Manuel

    2014-10-01

    Surgical site infection (SSI) is a common complication after vascular surgery. It may cause exposure of the underlying prosthesis causing graft infection, which may require the removal of the vascular graft, increasing amputation and mortality risks. Graft contamination usually occurs during operative procedure or by direct spread from an infected wound. It is therefore advisable to a strong effort in reducing SSI. Topic antibiotics have not been fully studied in vascular surgery, but collagen implant with gentamicin sulphate has shown to reduce SSI in cardiac surgery, orthopaedics, and general surgery procedures. Sixty (60) non-diabetic and non-obese patients with lower limb ischaemia with indication for femoropopliteal PTFE prosthetic bypass were allocated into 2 groups of 30 patients. A collagen implant impregnated with gentamicin sulphate (Collatamp(®)) was applied in the groin incision adjacent to the prosthesis in one group, and the other was a control group. The same surgical team operated all patients. Szilagyi classification was used. There was no SSI (0% - 0/30) in the collagen implant with gentamicin sulphate group, contrasting with 6 cases (20% - 6/30) of SSI (grade I and II) in the control group (p = 0.024). In-hospital day's data shows a significant difference between the two groups (p = 0.004) with a mean of 5.66 days for implant group and 8.10 days for control group. There was no SSI grade III. Collagen implant with gentamicin sulphate (Collatamp(®)) reduces SSI in the groin incision in ischaemic patients submitted to femoropopliteal PTFE prosthetic bypass. Days of hospitalization are also reduced. Decreasing SSI rate and in-hospital days, this implant may also reduce health care costs. Because this is a small pilot study, a multicentre RCT is necessary for validation. Copyright © 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

  9. Protective effect of pomegranate flower extract against gentamicin-induced renal toxicity in male rats

    OpenAIRE

    Sadeghi, Ferdos; Nematbakhsh, Mehdi; Noori-Diziche, Ali; Eshraghi-Jazi, Fatemeh; Talebi, Ardeshir; Nasri, Hamid; Mansouri, Azam; Dehghani, Aghdas; Saberi, Shadan; Shirdavani, Soheila; Ashrafi, Farzaneh

    2015-01-01

    Introduction: Gentamicin (GM) as an antibiotic is used in clinic. However, its administration is limited by side effects such as nephrotoxicity. Herbal extracts could be used in therapeutic approaches. Objectives: The present study was planned to investigate whether pomegranate flower extract (PFE) could ameliorate GM-induced renal toxicity in male rats. Materials and Methods: Twenty eight male Wistar rats were divided into 5 groups. Groups 1 and 2 respectively received PFE 25 and 50 mg/kg fo...

  10. Sensitive immunochemical approaches for quantitative (FPIA) and qualitative (lateral flow tests) determination of gentamicin in milk.

    Science.gov (United States)

    Beloglazova, N V; Shmelin, P S; Eremin, S A

    2016-01-01

    Three kinds of immunoassays for the determination of gentamicin in milk samples were developed and validated. First, a fast and easily-performed fluorescence polarization immunoassay was used for characterization of the employed polyclonal antibody. The calculated Kaff were (1.9±0.4)×10(9)М(-1) and (6.0±0.2)×10(6)М(-1) for the high- and low-affinity fractions respectively. The assay was characterized with a good sensitivity, the limit of detection being 5μgkg(-1). Two different kinds of detection labels, i.e. colloidal gold (CG) and quantum dots (QDs), were evaluated for use in lateral-flow format with respect to rapid visual on-site testing. The cut-off levels for both qualitative formats were selected based on the maximum level for gentamicin in milk established by the European Commission, 100μgkg(-1), resulting in a 10μgkg(-1) cut-off considering sample dilution. The intra-laboratory validation was performed with sterilized milk samples artificially spiked with gentamicin at concentrations less than, equal to, and greater than the cut-off level. It was shown that milk products could be analyzed without any sample preparation, except for dilution with the buffer solution. The rates of false-positive and false-negative results were below 5% for both labels. The different developed immunoassays were tested towards gentamicin determination in artificially-spiked and naturally contaminated milk samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Refractory episodic vertigo: role of intratympanic gentamicin and vestibular evoked myogenic potentials.

    Science.gov (United States)

    Celis-Aguilar, Erika; Hinojosa-González, Ramon; Vales-Hidalgo, Olivia; Coutinho-Toledo, Heloisa

    Even today, the treatment of intractable vertigo remains a challenge. Vestibular ablation with intratympanic gentamicin stands as a good alternative in the management of refractory vertigo patients. To control intractable vertigo through complete saccular and horizontal canal vestibular ablation with intratympanic gentamicin treatment. Patients with refractory episodic vertigo were included. The inclusion criteria were: unilateral ear disease, moderate to profound sensorineural hearing loss, and failure to other treatments. Included patients underwent 0.5-0.8mL of gentamicin intratympanic application at a 30mg/mL concentration. Vestibular ablation was confirmed by the absence of response on cervical vestibular evoked myogenic potentials and no response on caloric tests. Audiometry, electronystagmography with iced water, and vestibular evoked myogenic potentials were performed in all patients. Ten patients were included; nine patients with Meniere's disease and one patient with (late onset) delayed hydrops. Nine patients showed an absent response on vestibular evoked myogenic potentials and no response on caloric tests. The only patient with low amplitude on cervical vestibular evoked myogenic potentials had vertigo recurrence. Vertigo control was achieved in 90% of the patients. One patient developed hearing loss >30dB. Cervical vestibular evoked myogenic potentials confirmed vestibular ablation in patients treated with intratympanic gentamicin. High-grade vertigo control was due to complete saccular and horizontal canal ablation (no response to iced water in electronystagmography and no response on cervical vestibular evoked myogenic potentials). Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  12. Sildenafil Ameliorates Gentamicin-Induced Nephrotoxicity in Rats: Role of iNOS and eNOS

    Directory of Open Access Journals (Sweden)

    Mohamed A. Morsy

    2014-01-01

    Full Text Available Gentamicin, an aminoglycoside antibiotic, is used for the treatment of serious Gram-negative infections. However, its usefulness is limited by its nephrotoxicity. Sildenafil, a selective phosphodiesterase-5 inhibitor, was reported to prevent or decrease tissue injury. The aim of this study is to evaluate the potential protective effects of sildenafil on gentamicin-induced nephrotoxicity in rats. Male Wistar rats were injected with gentamicin (100 mg/kg/day, i.p. for 6 days with and without sildenafil. Sildenafil administration resulted in nephroprotective effect in gentamicin-intoxicated rats as it significantly decreased serum creatinine and urea, urinary albumin, and renal malondialdehyde and nitrite/nitrate levels, with a concomitant increase in renal catalase and superoxide dismutase activities compared to gentamicin-treated rats. Moreover, immunohistochemical examination revealed that sildenafil treatment markedly reduced inducible nitric oxide synthase (iNOS expression, while expression of endothelial nitric oxide synthase (eNOS was markedly enhanced. The protective effects of sildenafil were verified histopathologically. In conclusion, sildenafil protects rats against gentamicin-induced nephrotoxicity possibly, in part, through its antioxidant activity, inhibition of iNOS expression, and induction of eNOS production.

  13. Evaluation of various techniques for separation of non-polar modifier concentrates from petroleum waxy by-products

    Directory of Open Access Journals (Sweden)

    Fathi S. Soliman

    2014-09-01

    Full Text Available Two petroleum waxy by-products (light and middle slack wax crudes were evaluated for separation of non-polar modifiers by using different techniques. The results showed that, the light slack wax is selected as a suitable wax for separation of n-alkanes with even number of carbon atoms ranging from C20 to C26 for their high n-paraffin contents and can be used as non-polar structural modifiers. Different separation techniques; multistage fractional crystallization and liquid–solid chromatography; followed by the urea adduction technique have been used to separate non-polar modifier concentrates from the light slack wax crude. The light slack wax, its saturate components, the hard wax fractions isolated from light slack wax by the multistage fractional crystallization technique and their adducts were analyzed by GC to characterize and compare the produced components. The resulting data reveal that, the adducts of light slack wax and its saturate components; can be used as non-polar modifier concentrates of low carbon atoms (C20 + C22. From an economic point of view, the light slack wax adduct is selected as a non-polar modifier concentrate whereas, the separation step can be neglected to save energy. Meanwhile, the adduct of the hard wax isolated at 30 °C can be used as the preferable non-polar modifier concentrate of the high carbon number atoms (C24 + C26.

  14. Gentamicin loaded PLGA nanoparticles as local drug delivery system for the osteomyelitis treatment.

    Science.gov (United States)

    Posadowska, Urszula; Brzychczy-Włoch, Monika; Pamuła, Elżbieta

    2015-01-01

    Since there are more and more cases of multiresistance among microorganisms, rational use of antibiotics (especially their systemic vs. local application) is of great importance. Here we propose polymeric nanoparticles as locally applied gentamicin delivery system useful in osteomyelitis therapy. Gentamicin sulphate (GS) was encapsulated in the poly(lactide-co-glycolide) (PLGA 85:15) nanoparticles by double emulsification (water/oil/water, W1/O/W2). The nanoparticles were characterized by dynamic light scattering, laser electrophoresis and atomic force microscopy. UV-vis spectroscopy (O-phthaldialdehyde assay, OPA) and Kirby-Bauer tests were used to evaluate drug release and antimicrobial activity, respectively. Physicochemical characterization showed that size, shape and drug solubilization of the nanoparticles mainly depended on GS content and concentration of surface stabilizer (polyvinyl alcohol, PVA). Laser electrophoresis demonstrated negative value of zeta potential of the nanoparticles attributed to PLGA carboxyl end group presence. Drug release studies showed initial burst release followed by prolonged 35-day sustained gentamicin delivery. Agar-diffusion tests performed with pathogens causing osteomyelitis (Staphylococcus aureus and Staphylococcus epidermidis, both reference strains and clinical isolates) showed antibacterial activity of GS loaded nanoparticles (GS-NPs). It can be concluded that GS-NPs are a promising form of biomaterials useful in osteomyelitis therapy.

  15. A New Type of Biphasic Calcium Phosphate Cement as a Gentamicin Carrier for Osteomyelitis

    Directory of Open Access Journals (Sweden)

    Wen-Yu Su

    2013-01-01

    Full Text Available Osteomyelitis therapy is a long-term and inconvenient procedure for a patient. Antibiotic-loaded bone cements are both a complementary and alternative treatment option to intravenous antibiotic therapy for the treatment of osteomyelitis. In the current study, the biphasic calcium phosphate cement (CPC, called α-TCP/HAP (α-tricalcium phosphate/hydroxyapatite biphasic cement, was prepared as an antibiotics carrier for osteomyelitis. The developed biphasic cement with a microstructure of α-TCP surrounding the HAP has a fast setting time which will fulfill the clinical demand. The X-ray diffraction and Fourier transform infrared spectrometry analyses showed the final phase to be HAP, the basic bone mineral, after setting for a period of time. Scanning electron microscopy revealed a porous structure with particle sizes of a few micrometers. The addition of gentamicin in α-TCP/HAP would delay the transition of α-TCP but would not change the final-phase HAP. The gentamicin-loaded α-TCP/HAP supplies high doses of the antibiotic during the initial 24 hours when they are soaked in phosphate buffer solution (PBS. Thereafter, a slower drug release is produced, supplying minimum inhibitory concentration until the end of the experiment (30 days. Studies of growth inhibition of Staphylococcus aureus and Pseudomonas aeruginosa in culture indicated that gentamicin released after 30 days from α-TCP/HAP biphasic cement retained antibacterial activity.

  16. Application of a neural network for gentamicin concentration prediction in a general hospital population.

    Science.gov (United States)

    Corrigan, B W; Mayo, P R; Jamali, F

    1997-02-01

    Neural network (NN) computation is computer modeling based in part on simulation of the structure and function of the brain. These modeling techniques have been found useful as pattern recognition tools. In the present study, data including age, sex, height, weight, serum creatinine concentration, dose, dosing interval, and time of measurement were collected from 240 patients with various diseases being treated with gentamicin in a general hospital setting. The patient records were randomly divided into two sets: a training set of 220 patients used to develop relationships between input and output variables (peak and trough plasma concentrations) and a testing set (blinded from the NN) of 20 to test the NN. The network model was the back-propagation, feed-forward model. Various networks were tested, and the most accurate networks for peak and trough (calculated as mean percent error, root mean squared error of the testing group, and tau value between observed and predicted values) were reported. The results indicate that NNs can predict gentamicin serum concentrations accurately from various input data over a range of patient ages and renal function and may offer advantages over traditional dose prediction methods for gentamicin.

  17. Effect of Momordica dioica Roxb on gentamicin model of acute renal failure.

    Science.gov (United States)

    Jain, Avijeet; Singhai, A K

    2010-09-01

    The ethanolic extract of the fruits of Momordica dioica was studied for its protective and curative effect against gentamicin-induced acute renal injury in albino rats of both sexes. Gentamicin intoxicated group showed significant increase in blood urea (69.48 +/- 4.34) and serum creatinine (3.017 +/- 0.208) from normal levels 33.72 +/- 1.92 and 0.818 +/- 0.073, respectively, in control group. In the preventive regimen, the extract at dose levels of 200 mg kg(-1) showed significant reduction in the elevated blood urea (47.93 +/- 2.46) and serum creatinine (2.067 +/- 0.1745), respectively. This treatment normalised the histopathological changes compared to the intoxicated group. In the curative regimen at 200 mg kg(-1) blood urea was found to be 48.21 +/- 2.36 and serum creatinine level was 2.050 +/- 0.183, which revealed significant curative effect. In vivo antioxidant and free radial scavenging activities were also determined. The maximum free radical scavenging activity with ethanolic extract was the basis of selection of this extract for in vivo study. Reduced glutathione (GSH) level was significantly (p Momordica dioica seeds possesses marked nephroprotective and curative activities without any toxicity due to its antioxidant activity and could offer a promising role in the treatment of acute renal injury caused by nephrotoxin-like gentamicin.

  18. Changes in the treatment of Enterococcus faecalis infective endocarditis in Spain in the last 15 years: from ampicillin plus gentamicin to ampicillin plus ceftriaxone.

    Science.gov (United States)

    Pericas, J M; Cervera, C; del Rio, A; Moreno, A; Garcia de la Maria, C; Almela, M; Falces, C; Ninot, S; Castañeda, X; Armero, Y; Soy, D; Gatell, J M; Marco, F; Mestres, C A; Miro, J M

    2014-12-01

    The aim of this study was to assess changes in antibiotic resistance, epidemiology and outcome among patients with Enterococcus faecalis infective endocarditis (EFIE) and to compare the efficacy and safety of the combination of ampicillin and gentamicin (A+G) with that of ampicillin plus ceftriaxone (A+C). The study was a retrospective analysis of a prospective cohort of EFIE patients treated in our centre from 1997 to 2011. Thirty patients were initially treated with A+G (ampicillin 2 g/4 h and gentamicin 3 mg/kg/day) and 39 with A+C (ampicillin 2 g/4 h and ceftriaxone 2 g/12 h) for 4-6 weeks. Increased rates of high-level aminoglycoside resistance (HLAR; gentamicin MIC ≥512 mg/L, streptomycin MIC ≥1024 mg/L or both) were observed in recent years (24% in 1997-2006 and 49% in 2007-2011; p 0.03). The use of A+C increased over time: 1997-2001, 4/18 (22%); 2002-2006, 5/16 (31%); 2007-2011, 30/35 (86%) (p <0.001). Renal failure developed in 65% of the A+G group and in 34% of the A+C group (p 0.014). Thirteen patients (43%) in the A+G group had to discontinue treatment, whereas only one patient (3%) treated with A+C had to discontinue treatment (p <0.001). Only development of heart failure and previous chronic renal failure were independently associated with 1-year mortality, while the individual antibiotic regimen (A+C vs. A+G) did not affect outcome (OR, 0.7; 95% CI, 0.2-2.2; p 0.549). Our study shows that the prevalence of HLAR EFIE has increased significantly in recent years and that alternative treatment with A+C is safer than A+G, with similar clinical outcomes, although the sample size is too small to draw firm conclusions. Randomized controlled studies are needed to confirm these results.

  19. Genome-Wide Identification of Antimicrobial Intrinsic Resistance Determinants in Staphylococcus aureus

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Leng, Bingfeng; Haaber, Jakob

    2016-01-01

    The emergence of antimicrobial resistance severely threatens our ability to treat bacterial infections. While acquired resistance has received considerable attention, relatively little is known of intrinsic resistance that allows bacteria to naturally withstand antimicrobials. Gene products......, atpA, atpB, atpG and atpH, reduced the minimum inhibitory concentration (MIC) of gentamicin 16-fold. To elucidate the potential of the screen, we examined treatment efficacy in the Galleria mellonella infection model. Gentamicin efficacy was significantly improved, when treating larvae infected...

  20. Study of aac(6'Ie-aph(2″Ia Gene in Clinical Strain of Enterococci and Identification of High-Level Gentamicin Resistante Enterococci

    Directory of Open Access Journals (Sweden)

    N. Dadfarma

    2010-10-01

    Full Text Available Introduction & Objective: Enterococci have emerged as the leading nosocomial pathogens. In addition to natural resistance to many agents, enterococci have also developed plasmid- and transposon-mediated resistance to high concentrations of aminoglycosides. High-level gentamicin resistance (HLGR of enterococci results in the failure of drug synergism with an aminoglycoside plus cell-wall-active agents. HLGR (MIC=500μg/ml strains is usually due to the presence of the aac(6'Ie-aph(2″Ia gene . Materials & Methods: In the present experimental study 142 enterococci were isolated from the patients’ species. Identification was done by using standard methods and antimicrobial susceptibility test was performed by disc diffusion technique. MIC of Gentamicin was determined by a broth micro dilution method (NCCLS. PCR was performed to detect the aac(6'Ie-aph(2″Ia gene .Presence of the gene aac(6'-Ie-aph(2″-Ia was confirmed by digest with Sca1 enzyme. A PCR product was sequenced and BLAST analyzed at the NCBI database to be confirmed. Results: 62(43.7% out of the 142 isolates, were found to exhibit HLGR phenotype. MIC ranging from 512 to >1024 μg/ml in 55 HLGR isolates. All resistant isolates except one, were found to harbor the aac(6'Ie-aph(2″Ia gene. In our strain collection, 42% of E. faecalis and 44% of E. faecium were HLGR. In the HLGR isolates the prevalence of resistance to other antibiotics and Multi Drug Resistance (MDR was higher than non–HLGR.This prevalence in E.faecium was higher than E.faecalis. The sequence was compared with a published sequence and confirmed. Conclusion: Our results indicate that high prevalence of MDR and HLGR enterococcal colonization is an important problem in our medical centers.Spread of the aac(6'-Ie-aph(2″-Ia gene was responsible for HLGR among enterococci isolated from the patients in Tehran. (Sci J Hamadan Univ Med Sci 2010;17(3:25-32

  1. Nonpolar and semipolar InGaN/GaN multiple-quantum-well solar cells with improved carrier collection efficiency

    Science.gov (United States)

    Huang, Xuanqi; Fu, Houqiang; Chen, Hong; Zhang, Xiaodong; Lu, Zhijian; Montes, Jossue; Iza, Michael; DenBaars, Steven P.; Nakamura, Shuji; Zhao, Yuji

    2017-04-01

    We demonstrate the nonpolar and semipolar InGaN/GaN multiple-quantum-well (MQW) solar cells grown on the nonpolar m-plane and semipolar ( 20 2 ¯ 1 ) plane bulk GaN substrates. The optical properties and photovoltaic performance of the nonpolar and semipolar InGaN solar cells were systematically studied, and the results were compared to the conventional polar c-plane devices. The absorption spectra, current density-voltage (J-V) characteristics, external quantum efficiency (EQE), and internal quantum efficiency (IQE) were measured for nonpolar m-plane, semipolar ( 20 2 ¯ 1 ) plane, and polar c-plane InGaN/GaN MQW solar cells. Nonpolar m-plane InGaN/GaN MQW solar cells showed the best performance across all devices, with a high open-circuit voltage of 2.32 V, a low bandgap-voltage offset of 0.59 V, and the highest EQE and IQE. In contrast, the polar c-plane device showed the lowest EQE despite the highest absorption spectra. This huge difference is attributed to the better carrier transport and collection on nonpolar m-plane devices due to the reduced polarization effects, which were further confirmed by bias-dependent EQE measurements and energy band diagram simulations. This study demonstrates the high potential of nonpolar and semipolar InGaN solar cells and can serve as guidance for the future design and fabrication of high efficiency III-nitride solar cells.

  2. Activity of Daptomycin Alone and in Combination with Rifampin and Gentamicin against Staphylococcus aureus Assessed by Time-Kill Methodology▿ †

    Science.gov (United States)

    Credito, Kim; Lin, Gengrong; Appelbaum, Peter C.

    2007-01-01

    The synergistic effects of daptomycin plus gentamicin or rifampin were tested against 50 Staphylococcus aureus strains, with daptomycin MICs ranging between 0.25 and 8 μg/ml. Daptomycin sub-MICs combined with gentamicin concentrations lower than the MIC yielded synergy in 34 (68%) of the 50 strains. Daptomycin combined with rifampin yielded synergy in one vancomycin-intermediate S. aureus strain only, and virtually all synergy occurred between daptomycin and gentamicin. PMID:17220402

  3. Extracellular gentamicin reduces the activity of connexin hemichannels and interferes with purinergic Ca2+ signaling in HeLa cells

    Directory of Open Access Journals (Sweden)

    Vania A Figueroa

    2014-09-01

    Full Text Available Gap junction channels (GJCs and hemichannels (HCs are composed of protein subunits termed connexins (Cxs and are permeable to ions and small molecules. In most organs, GJCs communicate the cytoplasm of adjacent cells, while HCs communicate the intra and extracellular compartments. In this way, both channel types coordinate physiological responses of cell communities. Cx mutations explain several genetic diseases, including about 50% of autosomal recessive nonsyndromic hearing loss. However, the possible involvement of Cxs in the etiology of acquired hearing loss remains virtually unknown. Factors that induce post-lingual hearing loss are diverse, exposure to gentamicin an aminoglycoside antibiotic, being the most common. Gentamicin has been proposed to block GJCs, but its effect on HCs remains unknown. In this work, the effect of gentamicin on the functional state of HCs was studied and its effect on GJCs was reevaluated in HeLa cells stably transfected with Cxs. We focused on Cx26 because it is the main Cx expressed in the cochlea of mammals where it participates in purinergic signaling pathways. We found that gentamicin applied extracellularly reduces the activity of HCs, while dye transfer across GJCs was not affected. HCs were also blocked by streptomycin, another aminoglycoside antibiotic. Gentamicin also reduced the ATP release and the HC-dependent oscillations of cytosolic free-Ca2+ signal. Moreover, gentamicin drastically reduced the Cx26 HC-mediated membrane currents in Xenopus laevis oocytes. Therefore, the extracellular gentamicin-induced inhibition of Cx HCs may adversely affect autocrine and paracrine signaling, including the purinergic one, which might partially explain its ototoxic effects.

  4. Extracellular gentamicin reduces the activity of connexin hemichannels and interferes with purinergic Ca2+ signaling in HeLa cells

    Science.gov (United States)

    Figueroa, Vania A.; Retamal, Mauricio A.; Cea, Luis A.; Salas, José D.; Vargas, Aníbal A.; Verdugo, Christian A.; Jara, Oscar; Martínez, Agustín D.; Sáez, Juan C.

    2014-01-01

    Gap junction channels (GJCs) and hemichannels (HCs) are composed of protein subunits termed connexins (Cxs) and are permeable to ions and small molecules. In most organs, GJCs communicate the cytoplasm of adjacent cells, while HCs communicate the intra and extracellular compartments. In this way, both channel types coordinate physiological responses of cell communities. Cx mutations explain several genetic diseases, including about 50% of autosomal recessive non-syndromic hearing loss. However, the possible involvement of Cxs in the etiology of acquired hearing loss remains virtually unknown. Factors that induce post-lingual hearing loss are diverse, exposure to gentamicin an aminoglycoside antibiotic, being the most common. Gentamicin has been proposed to block GJCs, but its effect on HCs remains unknown. In this work, the effect of gentamicin on the functional state of HCs was studied and its effect on GJCs was reevaluated in HeLa cells stably transfected with Cxs. We focused on Cx26 because it is the main Cx expressed in the cochlea of mammals where it participates in purinergic signaling pathways. We found that gentamicin applied extracellularly reduces the activity of HCs, while dye transfer across GJCs was not affected. HCs were also blocked by streptomycin, another aminoglycoside antibiotic. Gentamicin also reduced the adenosine triphosphate release and the HC-dependent oscillations of cytosolic free-Ca2+ signal. Moreover, gentamicin drastically reduced the Cx26 HC-mediated membrane currents in Xenopus laevis oocytes. Therefore, the extracellular gentamicin-induced inhibition of Cx HCs may adversely affect autocrine and paracrine signaling, including the purinergic one, which might partially explain its ototoxic effects. PMID:25237294

  5. In Vitro Anticancer Activity of a Nonpolar Fraction from Gynostemma pentaphyllum (Thunb.) Makino

    Science.gov (United States)

    Li, Yantao; Huang, Jiajun; Lin, Wanjun; Yuan, Zhongwen; Feng, Senling; Xie, Ying; Ma, Wenzhe

    2016-01-01

    Gynostemma pentaphyllum (Thunb.) Makino (GpM) has been widely used in traditional Chinese medicine (TCM) for the treatment of various diseases including cancer. Most previous studies have focused primarily on polar fractions of GpM for anticancer activities. In this study, a nonpolar fraction EA1.3A from GpM showed potent growth inhibitory activities against four cancer cell lines with IC50 ranging from 31.62 μg/mL to 38.02 μg/mL. Furthermore, EA1.3A also inhibited the growth of breast cancer cell MDA-MB-453 time-dependently, as well as its colony formation ability. EA1.3A induced apoptosis on MDA-MB-453 cells both dose-dependently and time-dependently as analyzed by flow cytometry and verified by western blotting analysis of apoptosis marker cleaved nuclear poly(ADP-ribose) polymerase (cPARP). Additionally, EA1.3A induced cell cycle arrest in G0/G1 phase. Chemical components analysis of EA1.3A by GC-MS revealed that this nonpolar fraction from GpM contains 10 compounds including four alkaloids, three organic esters, two terpenes, and one catechol substance, and all these compounds have not been reported in GpM. In summary, the nonpolar fraction EA1.3A from GpM inhibited cancer cell growth through induction of apoptosis and regulation of cell cycle progression. Our study shed light on new chemical bases for the anticancer activities of GpM and feasibilities to develop new anticancer agents from this widely used medicinal plant. PMID:27034692

  6. In Vitro Anticancer Activity of a Nonpolar Fraction from Gynostemma pentaphyllum (Thunb. Makino

    Directory of Open Access Journals (Sweden)

    Yantao Li

    2016-01-01

    Full Text Available Gynostemma pentaphyllum (Thunb. Makino (GpM has been widely used in traditional Chinese medicine (TCM for the treatment of various diseases including cancer. Most previous studies have focused primarily on polar fractions of GpM for anticancer activities. In this study, a nonpolar fraction EA1.3A from GpM showed potent growth inhibitory activities against four cancer cell lines with IC50 ranging from 31.62 μg/mL to 38.02 μg/mL. Furthermore, EA1.3A also inhibited the growth of breast cancer cell MDA-MB-453 time-dependently, as well as its colony formation ability. EA1.3A induced apoptosis on MDA-MB-453 cells both dose-dependently and time-dependently as analyzed by flow cytometry and verified by western blotting analysis of apoptosis marker cleaved nuclear poly(ADP-ribose polymerase (cPARP. Additionally, EA1.3A induced cell cycle arrest in G0/G1 phase. Chemical components analysis of EA1.3A by GC-MS revealed that this nonpolar fraction from GpM contains 10 compounds including four alkaloids, three organic esters, two terpenes, and one catechol substance, and all these compounds have not been reported in GpM. In summary, the nonpolar fraction EA1.3A from GpM inhibited cancer cell growth through induction of apoptosis and regulation of cell cycle progression. Our study shed light on new chemical bases for the anticancer activities of GpM and feasibilities to develop new anticancer agents from this widely used medicinal plant.

  7. Study on Surface Properties for Non-polar Fluids with Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    吴畏; 陆九芳; 付东; 刘金晨; 李以圭

    2004-01-01

    The density functional theory, simplified by the local density approximation and mean-field approximation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, elk, d and ms, are regressed from the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters.

  8. A semiempirical model for estimating the hydration free energy of neutral nonpolar compounds

    Science.gov (United States)

    Ratkova, E. L.

    2012-10-01

    An improved semiempirical model for determining the hydration free energy of neutral nonpolar compounds is presented. The model is based on a combination of the RISM approach of the integral equation theory and empirical correlations. It is demonstrated that the developed model has high predictive ability for alkanes, alkenes, and dienes (present only in the test set of compounds). It is concluded that this semiempirical model can be applied in estimating the hydration free energy of more complicated structures based on saturated and nonsaturated aliphatic hydrocarbons.

  9. Storage lipids of yeasts: a survey of nonpolar lipid metabolism in Saccharomyces cerevisiae, Pichia pastoris, and Yarrowia lipolytica.

    Science.gov (United States)

    Koch, Barbara; Schmidt, Claudia; Daum, Günther

    2014-09-01

    Biosynthesis and storage of nonpolar lipids, such as triacylglycerols (TG) and steryl esters (SE), have gained much interest during the last decades because defects in these processes are related to severe human diseases. The baker's yeast Saccharomyces cerevisiae has become a valuable tool to study eukaryotic lipid metabolism because this single-cell microorganism harbors many enzymes and pathways with counterparts in mammalian cells. In this article, we will review aspects of TG and SE metabolism and turnover in the yeast that have been known for a long time and combine them with new perceptions of nonpolar lipid research. We will provide a detailed insight into the mechanisms of nonpolar lipid synthesis, storage, mobilization, and degradation in the yeast S. cerevisiae. The central role of lipid droplets (LD) in these processes will be addressed with emphasis on the prevailing view that this compartment is more than only a depot for TG and SE. Dynamic and interactive aspects of LD with other organelles will be discussed. Results obtained with S. cerevisiae will be complemented by recent investigations of nonpolar lipid research with Yarrowia lipolytica and Pichia pastoris. Altogether, this review article provides a comprehensive view of nonpolar lipid research in yeast.

  10. Aminoglycoside Resistance and Susceptibility Testing Errors in Acinetobacter baumannii-calcoaceticus Complex

    Science.gov (United States)

    2010-04-01

    evaluated AMEs detected by a combination of phenotypic inference and DNA hybridization in 1,189 Acineto- bacter sp. isolates from South Africa, Europe...resistance is prevalent, amikacin was used in greater quantities than gentamicin and tobramycin. While high rates of amikacin resistance in Acineto- bacter

  11. Gentamicin-induced ototoxicity and nephrotoxicity vary with circadian time of treatment and entail separate mechanisms.

    Science.gov (United States)

    Blunston, Mary A; Yonovitz, Al; Woodahl, Erica L; Smolensky, Michael H

    2015-01-01

    The aminoglycoside antibiotic gentamicin can cause both ototoxicity and nephrotoxicity, the severity of which varies with circadian time of daily treatment. However, it is not yet resolved if such drug-induced adverse effects are independent or interdependent phenomena. Two groups of 9 female Sprague-Dawley rats (200-250 g), each housed separately and entrained to a 12 h light (06:00-18:00 h) - 12 h dark cycle, received a daily subcutaneous injection of 100 mg/kg gentamicin. One group was treated at the beginning of the activity span, 2 Hours After Lights On (HALO), and the other at the beginning of the rest span, 14 HALO. Global toxicity was gauged by both body weight loss relative to the pre-treatment baseline and number of deaths. Ototoxicity, i.e., hearing loss, was assessed by changes in auditory brainstem response (ABR) for pure tone stimuli of 8, 16, 24, and 32 kHz before and after 2 and 4 weeks of gentamicin treatment. Renal toxicity was evaluated by changes in urinary N-acetyl-β-glucosaminidase (NAG)/creatinine (CR) concentration ratio before and after each week of treatment. In a complementary substudy of separate but comparable 2 and 14 HALO groups of rats, blood samples were obtained before and 30, 60, 120, and 240 min post-subcutaneous injection of 100 mg/kg gentamicin. Number of animal deaths was greater in the 2 (4 deaths) than 14 HALO (1 death) group, mirroring more severe initial (first two weeks of treatment) body weight losses from baseline, being more than 2-fold greater in animals of the 2 than 14 HALO group. Ototoxicity progressively worsened during the treatment; although, the extent of hearing loss varied according to circadian time of treatment across all frequencies (p ototoxicity. The mean urinary NAG/CR ratio peaked after the first week of treatment, averaging 13.64-fold greater than baseline for the 2 HALO-treated animals compared to 7.38-fold greater than baseline for the 14 HALO-treated ones. Ratio values declined

  12. Mesenchymal stem cell-conditioned medium accelerates regeneration of human renal proximal tubule epithelial cells after gentamicin toxicity.

    Science.gov (United States)

    Moghadasali, Reza; Mutsaers, Henricus A M; Azarnia, Mahnaz; Aghdami, Nasser; Baharvand, Hossein; Torensma, Ruurd; Wilmer, Martijn J G; Masereeuw, Rosalinde

    2013-07-01

    Bone marrow-derived mesenchymal stem cells (MSCs) have the capacity to regenerate renal tubule epithelia and repair renal function without fusing with resident tubular cells. The goal of the present project was to investigate the role of MSCs secreted cytokines on tubule cell viability and regeneration after a toxic insult, using a conditionally immortalized human proximal tubule epithelial cell (ciPTEC) line. Gentamicin was used to induce nephrotoxicity, and cell viability and migration were studied in absence and presence of human MSC-conditioned medium (hMSC-CM) i.e. medium containing soluble factors produced and secreted by MSCs. Exposure of ciPTEC to 0-3000 μg/ml gentamicin for 24 h caused a significant dose-dependent increase in cell death. We further demonstrated that the nephrotoxic effect of 2000 μg/ml gentamicin was recovered partially by exposing cells to hMSC-CM. Moreover, exposure of ciPTEC to gentamicin (1500-3000 μg/ml) for 7 days completely attenuated the migratory capacity of the cells. In addition, following scrape-wounding, cell migration of both untreated and gentamicin-exposed cells was increased in the presence of hMSC-CM, as compared to exposures to normal medium, indicating improved cell recovery. Our data suggest that cytokines secreted by MSCs stimulate renal tubule cell regeneration after nephrotoxicity. Copyright © 2012 Elsevier GmbH. All rights reserved.

  13. Neurotrophic and antioxidant effects of silymarin comparable to 4-methylcatechol in protection against gentamicin-induced ototoxicity in guinea pigs.

    Science.gov (United States)

    Draz, Eman I; Abdin, Amany A; Sarhan, Naglaa I; Gabr, Takwa A

    2015-04-01

    Despite that gentamicin is a very effective aminoglycoside, its potential ototoxicity which is of irreversible nature makes a challenge and limitation for its use. This study was designed to investigate possible neurotrophic and antioxidant effects of silymarin comparable to 4-methylcatechol in protection against gentamicin-induced ototoxicity. Twenty pigmented guinea pigs were divided into four equal groups, where group I served as normal control group. The other groups received gentamicin (120 mg/kg/day, ip) for 19 days where group II given vehicle of 1% CMC, group III and group IV were pre-treated 2h before gentamicin by 4-methylcatechol (10 μg/kg, ip) and silymarin (100mg/kg, oral gavage), respectively. The main findings indicated that silymarin exhibited restoration of nerve growth factor (NGF) levels and increased tropomyosin-related kinase receptors-A (Trk-A) m-RNA expression in cochlear tissue and preservation of hair cells of organ of Corti by scanning electron microscopy (SEM) with significant decrease in auditory brainstem response (ABR) threshold compared to 4-methylcatechol. Only silymarin caused significant amelioration in oxidative stress state by reducing malondialdehyde (MDA) levels and increasing catalase activity. Silymarin exerts superiority over 4-methylcatechol when recommended as protective agent against gentamicin ototoxicity based on its efficient neurotrophic and antioxidant activities. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  14. Gentamicin-loaded wound dressing with polyvinyl alcohol/dextran hydrogel: gel characterization and in vivo healing evaluation.

    Science.gov (United States)

    Hwang, Ma-Ro; Kim, Jong Oh; Lee, Jeong Hoon; Kim, Yong Il; Kim, Jeong Hoon; Chang, Sun Woo; Jin, Sung Gju; Kim, Jung Ae; Lyoo, Won Seok; Han, Sung Soo; Ku, Sae Kwang; Yong, Chul Soon; Choi, Han-Gon

    2010-09-01

    To develop a gentamicin-loaded wound dressing, cross-linked hydrogel films were prepared with polyvinyl alcohol (PVA) and dextran using the freezing-thawing method. Their gel properties such as gel fraction, swelling, water vapor transmission test, morphology, tensile strength, and thermal property were investigated. In vitro protein adsorption test, in vivo wound healing test, and histopathology were performed. Dextran decreased the gel fraction, maximum strength, and thermal stability of hydrogels. However, it increased the swelling ability, water vapor transmission rate, elasticity, porosity, and protein adsorption. The drug gave a little positive effect on the gel properties of hydrogels. The gentamicin-loaded wound dressing composed of 2.5% PVA, 1.13% dextran, and 0.1% drug was more swellable, flexible, and elastic than that with only PVA because of its cross-linking interaction with PVA. In particular, it could provide an adequate level of moisture and build up the exudates on the wound area. From the in vivo wound healing and histological results, this gentamicin-loaded wound dressing enhanced the healing effect more compared to conventional product because of the potential healing effect of gentamicin. Thus, this gentamicin-loaded wound dressing would be used as a potential wound dressing with excellent forming and improved healing effect in wound care.

  15. Co-delivery of ibuprofen and gentamicin from nanoporous anodic titanium dioxide layers.

    Science.gov (United States)

    Pawlik, Anna; Jarosz, Magdalena; Syrek, Karolina; Sulka, Grzegorz D

    2017-04-01

    Although single-drug therapy may prove insufficient in treating bacterial infections or inflammation after orthopaedic surgeries, complex therapy (using both an antibiotic and an anti-inflammatory drug) is thought to address the problem. Among drug delivery systems (DDSs) with prolonged drug release profiles, nanoporous anodic titanium dioxide (ATO) layers on Ti foil are very promising. In the discussed research, ATO samples were synthesized via a three-step anodization process in an ethylene glycol-based electrolyte with fluoride ions. The third step lasted 2, 5 and 10min in order to obtain different thicknesses of nanoporous layers. Annealing the as-prepared amorphous layers at the temperature of 400°C led to obtaining the anatase phase. In this study, water-insoluble ibuprofen and water-soluble gentamicin were used as model drugs. Three different drug loading procedures were applied. The desorption-desorption-diffusion (DDD) model of the drug release was fitted to the experimental data. The effects of crystalline structure, depth of TiO2 nanopores and loading procedure on the drug release profiles were examined. The duration of the drug release process can be easily altered by changing the drug loading sequence. Water-soluble gentamicin is released for a long period of time if gentamicin is loaded in ATO as the first drug. Additionally, deeper nanopores and anatase phase suppress the initial burst release of drugs. These results confirm that factors such as morphological and crystalline structure of ATO layers, and the procedure of drug loading inside nanopores, allow to alter the drug release performance of nanoporous ATO layers.

  16. Electrochemical detection of tobramycin or gentamicin according to the European Pharmacopoeia analytical method.

    Science.gov (United States)

    Ghinami, C; Giuliani, V; Menarini, A; Abballe, F; Travaini, S; Ladisa, T

    2007-01-12

    Tobramycin and gentamicin are two aminoglycosidic antibiotics used in lung infection, ophthalmic treatments as well as in skin infections. Pharmaceutical companies which produce remedies containing tobramycin and gentamicin need an analytical method for their internal quality control. For several years a simple chromatographic method based on anion exchange separation coupled with amperometric detection was proposed for aminoglycosides. This analytical approach was partially used in the last edition of the European Pharmacopoeia (EP) for tobramycin and gentamicin analysis. In fact they use integrated pulsed amperometric detection (IPAD) on a gold electrode while the separation is obtained on a polymeric wide pore reversed phase instead of anion exchange in alkaline conditions. Such coupling seems to be cumbersome and not so easy to realize and to reproduce from one laboratory to another. Besides, the described method lacks some of the details as important as the waveform steps duration. Unfortunately the quality control (QC) laboratories have to use exactly the method described in the EP, so they complained about the troubles. Therefore, the EP authors published recently a paper regarding the guidelines for good practice in the method application, but the suggestion was not yet resolutive. In our work we evaluated the eluent composition and the kind of amperometric cell, work electrode diameter and cell volume. Mainly we optimized the amperometric waveform. In addition, for tobramycin analysis another chromatographic phase was explored in order to achieve better efficiency and to separate all the impurities confirming the effectiveness of the detection. The conditions described in the paper seem to allow the analyst to operate in conformity with the EP method.

  17. Using Six Sigma to improve once daily gentamicin dosing and therapeutic drug monitoring performance.

    LENUS (Irish Health Repository)

    Egan, Sean

    2012-08-07

    BACKGROUND: Safe, effective therapy with the antimicrobial gentamicin requires good practice in dose selection and monitoring of serum levels. Suboptimal therapy occurs with breakdown in the process of drug dosing, serum blood sampling, laboratory processing and level interpretation. Unintentional underdosing may result. This improvement effort aimed to optimise this process in an academic teaching hospital using Six Sigma process improvement methodology. METHODS: A multidisciplinary project team was formed. Process measures considered critical to quality were defined, and baseline practice was examined through process mapping and audit. Root cause analysis informed improvement measures. These included a new dosing and monitoring schedule, and standardised assay sampling and drug administration timing which maximised local capabilities. Three iterations of the improvement cycle were conducted over a 24-month period. RESULTS: The attainment of serum level sampling in the required time window improved by 85% (p≤0.0001). A 66% improvement in accuracy of dosing was observed (p≤0.0001). Unnecessary dose omission while awaiting level results and inadvertent disruption to therapy due to dosing and monitoring process breakdown were eliminated. Average daily dose administered increased from 3.39 mg\\/kg to 4.78 mg\\/kg\\/day. CONCLUSIONS: Using Six Sigma methodology enhanced gentamicin usage process performance. Local process related factors may adversely affect adherence to practice guidelines for gentamicin, a drug which is complex to use. It is vital to adapt dosing guidance and monitoring requirements so that they are capable of being implemented in the clinical environment as a matter of routine. Improvement may be achieved through a structured localised approach with multidisciplinary stakeholder involvement.

  18. Inhibition of K+ currents in type I vestibular hair cells by gentamicin and neomycin.

    Science.gov (United States)

    Mann, Scott E; Johnson, Matthew; Meredith, Frances L; Rennie, Katherine J

    2013-01-01

    Significant ototoxicity limits the use of aminoglycoside (AG) antibiotics. Several mechanisms may contribute to the death of both auditory and vestibular hair cells. In this study the effects of gentamicin and neomycin on K(+) currents in mature and early postnatal type I vestibular hair cells (HCI) were tested directly. The whole-cell patch clamp technique was used to assess the effects of AG and KCNQ channel modulators on K(+) currents (IK) in HCI acutely isolated from gerbil semicircular canals. Extracellular neomycin (1 mM) rapidly reduced peak outward IK by 16 ± 4% (n = 9) in mature HCI (postnatal days, P, 25-66). Gentamicin (5 mM) reduced outward IK by 16 ± 3% (n = 8). A similar reduction in outward current was seen in immature HCI (P5-9) that lacked the low-voltage-activated component of IK observed in mature cells. Intracellular application of gentamicin and neomycin also reduced IK in mature HCI. Modulators of KCNQ channels were used to probe KCNQ channel involvement. The selective KCNQ antagonist XE991 did not reduce IK and the neomycin-induced reduction in IK was not reversed by the KCNQ agonist flupirtine. Application of intracellular poly-D-lysine to sequester PIP2 did not reduce IK. Application of the K(+) channel blocker 4-aminopyridine (4-AP) strongly reduced IK, and extracellular AG in the presence of 4-AP gave no further inhibition of IK. In summary, AG significantly reduce the 4-AP-sensitive IK in early postnatal and mature HCI. K(+) current inhibition differs from that seen in outer hair cells, since it does not appear to involve PIP2 sequestration or KCNQ channels.

  19. Determination of vapor pressures for nonpolar and semipolar organic compounds from gas chromatographic retention data

    Science.gov (United States)

    Hinckley, D.A.; Bidleman, T.F.; Foreman, W.T.; Tuschall, J.R.

    1990-01-01

    Vapor pressures for nonpolar and moderately polar organochlorine, pyrethroid, and organophosphate insecticides, phthalate esters, and organophosphate flame retardants were determined by capillary gas chromatography (GC). Organochlorines and polycyclic aromatic hydrocarbons with known liquid-phase vapor pressures (P??L) (standard compounds) were chromatographed along with two reference compounds n-C20 (elcosane) and p,p???-DDT on a 1.0-m-long poly(dimethylsiloxane) bonded-phase (BP-1) column to determine their vapor pressures by GC (P??GC). A plot of log P??L vs log P??GC for standard compounds was made to establish a correlation between measured and literature values, and this correlation was then used to compute P??L of test compounds from their measured P??GC. P??L of seven major components of technical chlordane, endosulfan and its metabolites, ??-hexachlorocyclohexane, mirex, and two components of technical toxaphene were determined by GC. This method provides vapor pressures within a factor of 2 of average literature values for nonpolar compounds, similar to reported interlaboratory precisions of vapor pressure determinations. GC tends to overestimate vapor pressures of moderately polar compounds. ?? 1990 American Chemical Society.

  20. A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces.

    Science.gov (United States)

    Yu, Liping; Zunger, Alex

    2014-10-13

    The discovery of conductivity and magnetism at the polar-nonpolar interfaces of insulating nonmagnetic oxides such as LaAlO3 and SrTiO3 has raised prospects for attaining interfacial functionalities absent in the component materials. Yet, the microscopic origin of such emergent phenomena remains unclear, posing obstacles to design of improved functionalities. Here we present first principles calculations of electronic and defect properties of LaAlO3/SrTiO3 interfaces and reveal a unifying mechanism for the origins of both conductivity and magnetism. We demonstrate that the polar discontinuity across the interface triggers thermodynamically the spontaneous formation of certain defects that in turn cancel the polar field induced by the polar discontinuity. The ionization of the spontaneously formed surface oxygen vacancy defects leads to interface conductivity, whereas the unionized Ti-on-Al antisite defects lead to interface magnetism. The proposed mechanism suggests practical design principles for inducing and controlling both conductivity and magnetism at general polar-nonpolar interfaces.

  1. Characterizations of nonlinear optical properties on GaN crystals in polar, nonpolar, and semipolar orientations

    Science.gov (United States)

    Chen, Hong; Huang, Xuanqi; Fu, Houqiang; Lu, Zhijian; Zhang, Xiaodong; Montes, Jossue A.; Zhao, Yuji

    2017-05-01

    We report the basic nonlinear optical properties, namely, two-photon absorption coefficient ( β ), three-photon absorption coefficient ( γ ), and Kerr nonlinear refractive index ( n kerr), of GaN crystals in polar c-plane, nonpolar m-plane, and semipolar ( 20 21 ¯ ) plane orientations. A typical Z-scan technique was used for the measurement with a femtosecond Ti:S laser from wavelengths of 724 nm to 840 nm. For the two-photon absorption coefficient ( β ), similar values were obtained for polar, nonpolar, and semipolar samples, which are characterized to be ˜0.90 cm/GW at 724 nm and ˜0.65 cm/GW at 730 nm for all the three samples. For the Kerr nonlinear refractive index ( n kerr), self-focusing features were observed in this work, which is different from previous reports where self-defocusing features were observed on GaN in the visible and near-UV spectral regions. At 724 nm, n kerr was measured to be ˜2.5 0 × 10 - 14 cm 2 / W for all three samples. Three-photon absorption coefficients ( γ ) were also determined, which were found to be consistent with previous reports. This study provides valuable information on the basic nonlinear optical properties of III-nitride semiconductors, which are vital for a wide range of applications such as integrated photonics and quantum photonics.

  2. Dermoscopic features of basal cell carcinomas: differences in appearance under non-polarized and polarized light.

    Science.gov (United States)

    Liebman, Tracey N; Jaimes-Lopez, Natalia; Balagula, Yevgeniy; Rabinovitz, Harold S; Wang, Steven Q; Dusza, Stephen W; Marghoob, Ashfaq A

    2012-03-01

    Basal cell carcinomas (BCCs) can be diagnosed using different dermoscopic modalities. To evaluate dermoscopic features of BCCs using nonpolarized and polarized dermoscopy to highlight similarities and differences between dermoscopic modalities. Retrospective study of 149 BCCs under nonpolarized dermoscopy (NPD), polarized contact dermoscopy (PCD), and polarized noncontact dermoscopy (PNCD). Images were evaluated for a range of dermoscopic colors, structures, and vessels. Features were compared according to histopathologic subtype. The most common dermoscopic structures in BCCs across all modalities included globules (50.3-51.0%), dots (49.7-50.3%), white structureless areas (63.1-74.5%), structureless gray-brown areas (24.2-24.8%), and ulcerations (28.2%). The most frequently observed vasculature included arborizing vessels (18.8-38.3%), short fine telangiectasias (SFTs) (73.8-82.6%), and vascular blush (41.6-83.2%). Structures with higher levels of agreement across modalities included pigmented structures and ulcerations. Lower levels of agreement existed between contact and noncontact modalities for certain vascular features. White shiny structures, which include shiny white lines (chrysalis and crystalline structures) (0-69.1%), shiny white areas (0-25.5%), and rosettes (0-11.4%), exhibited no agreement between NPD and polarized modalities. This study highlights differences in dermoscopic features of BCCs under three dermoscopic modalities. Shiny white lines (chrysalis and crystalline structures) and shiny white areas may be used as additional criteria to diagnose BCCs. © 2011 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  3. Relative effectiveness of pretreatments on performance of Rhizomucor miehei lipase in nonpolar reaction media.

    Science.gov (United States)

    Garcia, Rafael A; Riley, Mark R

    2005-02-01

    Enzymes can be used in nonpolar reaction media to modify water-insoluble substrates. A variety of pretreatments, applied to the enzyme prior to introduction to the nonpolar media, can improve enzyme activity. However, the various pretreatments have not been studied using directly comparable conditions, nor have they been applied simultaneously to test for interactive effects. This work evaluates pretreatment of lipase with various classes of additives. The pretreated lipase is used to catalyze esterification between citronellol and acetic acid in a medium of n-hexane. The effectiveness of a particular pretreatment is presented in terms of relative performance (RP), which is equal to the number of times faster the pretreated lipase catalyzes the reaction relative to untreated lipase. The individual and interactive effects of the pretreatment factors were studied and compared. Buffer salts had a much stronger performance-enhancing effect than nonbuffer salts; pretreatment with 90% (w/w) sodium phosphate yielded lipase with an RP of approx 64. A strong interaction was found between the treatments with sodium phosphate and pH adjustment. These treatments may mitigate the inhibitory effect of acetic acid. Activating effects of phase interfaces and active-site protectants are shown to be complementary to other treatments, demonstrating that they likely act by distinct mechanisms.

  4. High indium non-polar InGaN clusters with infrared sensitivity grown by PAMBE

    Directory of Open Access Journals (Sweden)

    Shruti Mukundan

    2015-03-01

    Full Text Available Studies on the optical properties of InGaN alloy of relatively higher indium content are of potential interest to understand the effect of indium content on the optical band gap of epitaxial InGaN. We report the growth of self assembled non-polar high indium clusters of In0.55Ga0.45N over non-polar (11-20 a-plane In0.17Ga0.83N epilayer grown on a-plane (11-20GaN/(1-102 r-plane sapphire substrate using plasma assisted molecular beam epitaxy (PAMBE. Such structures are potential candidates for high brightness LEDs emitting in longer wavelengths. The high resolution X-ray diffraction studies revealed the formation of two distinct compositions of InxGa1−xN alloys, which were further confirmed by photoluminescence studies. A possible mechanism for the formation of such structure was postulated which was supported with the results obtained by energy dispersive X-ray analysis. The structure hence grown when investigated for photo-detecting properties, showed sensitivity to both infrared and ultraviolet radiations due to the different composition of InGaN region.

  5. Morphological, structural and electrical investigations on non-polar a-plane ZnO epilayers

    Science.gov (United States)

    Lautenschlaeger, Stefan; Eisermann, Sebastian; Hofmann, Michael N.; Roemer, Udo; Pinnisch, Melanie; Laufer, Andreas; Meyer, Bruno K.; von Wenckstern, Holger; Lajn, Alexander; Schmidt, Florian; Grundmann, Marius; Blaesing, Juergen; Krost, Alois

    2010-07-01

    We report on the growth of non-polar a-plane ZnO by CVD on r-plane-sapphire-wafers, a-plane GaN-templates and a-plane ZnO single-crystal substrates. Only the homoepitaxial growth approach leads to a Frank-van-der-Merwe growth mode, as shown by atomic force microscopy. The X-ray-diffraction spectra of the homoepitaxial thin films mirror the excellent crystalline quality of the ZnO substrate. The morphological and the structural quality of the homoepitaxial films is comparable to the best results for the growth on c-plane ZnO-substrates. The impurity incorporation, especially of group III elements, seems to be reduced when growing on the non-polar a-plane surface compared to the c-plane films as demonstrated by secondary ion mass spectrometry (SIMS). Optical properties have been investigated using low temperature photoluminescence measurements. We employed capacitance-voltage measurements ( C- V) to measure the background carrier density and its profile from substrate/film interface throughout the film to the surface. In thermal admittance spectroscopy (TAS) specific traps could be distinguished, and their thermal activation energies and capture cross sections could be determined.

  6. High indium non-polar InGaN clusters with infrared sensitivity grown by PAMBE

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Shruti; Mohan, Lokesh; Chandan, Greeshma; Krupanidhi, S. B., E-mail: sbk@mrc.iisc.ernet.in; Shinde, Satish; Nanda, K. K. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Maiti, R.; Ray, S. K. [Department of Physics, Indian Institute of Technology, Kharagpur (India)

    2015-03-15

    Studies on the optical properties of InGaN alloy of relatively higher indium content are of potential interest to understand the effect of indium content on the optical band gap of epitaxial InGaN. We report the growth of self assembled non-polar high indium clusters of In{sub 0.55}Ga{sub 0.45}N over non-polar (11-20) a-plane In{sub 0.17}Ga{sub 0.83}N epilayer grown on a-plane (11-20)GaN/(1-102) r-plane sapphire substrate using plasma assisted molecular beam epitaxy (PAMBE). Such structures are potential candidates for high brightness LEDs emitting in longer wavelengths. The high resolution X-ray diffraction studies revealed the formation of two distinct compositions of In{sub x}Ga{sub 1−x}N alloys, which were further confirmed by photoluminescence studies. A possible mechanism for the formation of such structure was postulated which was supported with the results obtained by energy dispersive X-ray analysis. The structure hence grown when investigated for photo-detecting properties, showed sensitivity to both infrared and ultraviolet radiations due to the different composition of InGaN region.

  7. Pharmacokinetic modeling of gentamicin in treatment of infective endocarditis: Model development and validation of existing models

    Science.gov (United States)

    van der Wijk, Lars; Proost, Johannes H.; Sinha, Bhanu; Touw, Daan J.

    2017-01-01

    Gentamicin shows large variations in half-life and volume of distribution (Vd) within and between individuals. Thus, monitoring and accurately predicting serum levels are required to optimize effectiveness and minimize toxicity. Currently, two population pharmacokinetic models are applied for predicting gentamicin doses in adults. For endocarditis patients the optimal model is unknown. We aimed at: 1) creating an optimal model for endocarditis patients; and 2) assessing whether the endocarditis and existing models can accurately predict serum levels. We performed a retrospective observational two-cohort study: one cohort to parameterize the endocarditis model by iterative two-stage Bayesian analysis, and a second cohort to validate and compare all three models. The Akaike Information Criterion and the weighted sum of squares of the residuals divided by the degrees of freedom were used to select the endocarditis model. Median Prediction Error (MDPE) and Median Absolute Prediction Error (MDAPE) were used to test all models with the validation dataset. We built the endocarditis model based on data from the modeling cohort (65 patients) with a fixed 0.277 L/h/70kg metabolic clearance, 0.698 (±0.358) renal clearance as fraction of creatinine clearance, and Vd 0.312 (±0.076) L/kg corrected lean body mass. External validation with data from 14 validation cohort patients showed a similar predictive power of the endocarditis model (MDPE -1.77%, MDAPE 4.68%) as compared to the intensive-care (MDPE -1.33%, MDAPE 4.37%) and standard (MDPE -0.90%, MDAPE 4.82%) models. All models acceptably predicted pharmacokinetic parameters for gentamicin in endocarditis patients. However, these patients appear to have an increased Vd, similar to intensive care patients. Vd mainly determines the height of peak serum levels, which in turn correlate with bactericidal activity. In order to maintain simplicity, we advise to use the existing intensive-care model in clinical practice to avoid

  8. Synergy effects of the antibiotics gentamicin and the essential oil of Croton zehntneri.

    Science.gov (United States)

    Rodrigues, Fabíola F G; Costa, José G M; Coutinho, Henrique D M

    2009-11-01

    The leaves of Croton zehntneri Pax et Hoffm (Euphorbiaceae) were subjected to hydrodistillation, and the essential oil extracted was examined with respect to antibacterial and antibiotic modifying activity by gaseous contact. The gaseous component of the oil inhibited the bacterial growth of Staphylococcus aureus and Pseudomonas aeruginosa with a MID of 0.5 and<1mg/l air, respectively. The activity of the antibiotic gentamicin was increased by 42,8% against P. aeruginosa after contact with the gaseous component, showing that this oil influences the activity of the antibiotic and may be used as an adjuvant in the antibiotic therapy of respiratory tract bacterial pathogens.

  9. Combined action of carbenicillin and gentamicin on Pseudomonas aeruginosa in vitro.

    Science.gov (United States)

    Sonne, M; Jawetz, E

    1969-06-01

    The minimal inhibitory and minimal bactericidal concentrations of carbenicillin and gentamicin were determined for 10 strains of Pseudomonas aeruginosa isolated from the urinary tract. Combinations of the two drugs were tested for possible enhanced activity. Such enhancement was demonstrated in the inhibitory activity of combinations for eight strains. Striking bactericidal activity against five strains was achieved by the combination, whereas neither drug alone in low dosage was capable of bactericidal action. The possible mode of action and the possible merit of pursuing these preliminary findings are discussed.

  10. The Protective Effects of Carrot Seed Extract on Spermatogenesis and Cauda Epididymal Sperm Reserves in Gentamicin Treated Rats

    Directory of Open Access Journals (Sweden)

    Mohammad Nouri

    2009-01-01

    Full Text Available Objective: Carrot (Daucus carota L. is known to possess antifertility properties in female.However, according to Iranian traditional medicine, it can increase the potency in men. Theaim of this study was to investigate the influence of carrot seed extract (CSE on spermatogenesis,number and motility of sperms in cauda epididyme in male rats.Materials and Methods: Forty adult male rats were randomly divided into 5 groups: controlgroup, groups receiving low- and high doses of CSE, animals that received high-dose of CSEwith gentamicin, and a gentamicin only group. After 4 weeks treatment, fasting serum sampleswere obtained for the sex hormone analysis. Under anesthesia, testis, cauda epididymidesand sperm ducts were dissected and sperm count, motility and cauda epididymis spermreserves (CESR were determined. Histopathological changes of testis were also studied toassess spermatogenesis. Data analysis was performed using one-way ANOVA followed byTukey HSD tests.Results: Administration of CSE caused a significant increase in CESR compared with thecontrol (28.2 ± 1.8 vs. 45.1 ± 2.0, ×106. The extract could also protect testis from the gentamicin-induced necrosis. The CSE administration caused about 3.5-times increase in theLH levels even in spite of receiving 5 mg/kg/day gentamicin with no significant effect on FSHlevels. The testosterone concentrations in the group received 400 mg/kg CSE were 30% and83% higher than its levels in the control and the gentamicin treated group, respectively.Conclusion: CSE can overcome reproductive toxicity of gentamicin and induces spermatogenesisprobably mainly through the elevation of testosterone levels.

  11. Antibacterial efficacy of core-shell nanostructures encapsulating gentamicin against an in vivo intracellular  Salmonella model

    Directory of Open Access Journals (Sweden)

    Ashish Ranjan

    2009-12-01

    Full Text Available Ashish Ranjan1, Nikorn Pothayee2,3, Mohammed N Seleem2, Ronald D Tyler Jr4, Bonnie Brenseke4, Nammalwar Sriranganathan2,4, Judy S Riffle2,3, Ramanathan Kasimanickam11Department of Large Animal Clinical Sciences, 2Institute for Critical Technology and Applied Science, 3Macromolecules and Interfaces Institute, 4Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, VAAbstract: Pluronic based core-shell nanostructures encapsulating gentamicin were designed in this study. Block copolymers of (PAA–+Na-b-(PEO-b-PPO-b-PEO-b-PAA– +Na were blended with PAA– Na+ and complexed with the polycationic antibiotic gentamicin to form nanostructures. Synthesized nanostructures had a hydrodynamic diameter of 210 nm, zeta potentials of –0.7 (±0.2, and incorporated ~20% by weight of gentamicin. Nanostructures upon co-incubation with J774A.1 macrophage cells showed no adverse toxicity in vitro. Nanostructures administered in vivo either at multiple dosage of 5 µg g–1 or single dosage of 15 µg g–1 in AJ-646 mice infected with Salmonella resulted in significant reduction of viable bacteria in the liver and spleen. Histopathological evaluation for concentration-dependent toxicity at a dosage of 15 µg g–1 revealed mineralized deposits in 50% kidney tissues of free gentamicin-treated mice which in contrast was absent in nanostructure-treated mice. Thus, encapsulation of gentamicin in nanostructures may reduce toxicity and improve in vivo bacterial clearance.Keywords: gentamicin, core-shell nanostructures, Salmonella

  12. Covalent and non-covalent functionalization and solubilization of double-walled carbon nanotubes in nonpolar and aqueous media

    Indian Academy of Sciences (India)

    L S Panchakarla; A Govindaraj

    2008-11-01

    Double-walled carbon nanotubes (DWNTs) have been functionalized by both covalent and non-covalent means. Covalent functionalization has been carried out by attaching an aliphatic amide function to DWNTs which enable solubilization in non-polar solvents. Solubilization in non-polar solvents has also been accomplished by non-covalent functionalization by using 1-pyrenebutanoicacid succinimidyl ester (PYBS). Non-covalent functionalization of DWNTs has been carried out by using polyethylene glycol (PEG) and polyoxyethylene(40)nonylphenyl ether (IGPAL), both of which enable solubilization in aqueous media. These functionalized DWNTs have been characterized by transmission electron microscopy, IR and Raman spectroscopy.

  13. Quantitative differences in antibiotic resistance between methicillin-resistant and methicillin-susceptible Staphylococcus aureus strains isolated in Hungary, Austria and Macedonia.

    Science.gov (United States)

    Horvath, A; Rozgonyi, F; Pesti, N; Kocsis, E; Malmos, G; Kristof, K; Nagy, K; Lagler, H; Presterl, E; Stich, K; Gattringer, R; Kotolacsi, G; Cekovska, Z; Graninger, W

    2010-08-01

    The aim of this study was to compare the quantitative susceptibility of methicillin-resistant and -susceptible Staphylococcus aureus (MRSA and MSSA) strains from three European countries to nine antistaphylococcal agents. The antibiotic susceptibility of 274 MRSA and 284 MSSA strains from Hungary, Austria and macedonia was tested by the broth microdilution method. The clonal relationship of strains was determined by pulsed-field gel electrophoresis. Intermediate susceptibility to vancomycin appeared in Macedonian MRSA strains. Macedonian MRSA strains had high-level amikacin and gentamicin resistance. MSSA strains generally were susceptible to all drugs at minimum inhibitory concentrations (MIC(50)) except for gentamicin resistance in Macedonian strains. In Hungary and Austria a common antibiotic resistance phenotype of MRSA predominated, while in macedonia three other phenotypes were also prevalent. Geographical differences in the resistance of S. aureus are still high. Since resistance levels of MRSA and MSSA strains differ extensively, they should be considered separately for antibiotic resistance analysis.

  14. Plasmid-determined resistance to fosfomycin in Serratia marcescens.

    Science.gov (United States)

    Mendoza, C; Garcia, J M; Llaneza, J; Mendez, F J; Hardisson, C; Ortiz, J M

    1980-08-01

    Multiple-antibiotic-resistant strains of Serratia marcescens isolated from hospitalized patients were examined for their ability to transfer antibiotic resistance to Escherichia coli by conjugation. Two different patterns of linked transferable resistance were found among the transconjugants. The first comprised resistance to carbenicillin, streptomycin, and fosfomycin; the second, and more common, pattern included resistance to carbenicillin, streptomycin, kanamycin, gentamicin, tetracycline, chloramphenicol, sulfonamide, and fosfomycin. The two types of transconjugant strains carried a single plasmid of either 57 or 97 megadaltons in size. Both of these plasmids are present in parental S. marcescens strains resistant to fosfomycin. The 57-megadalton plasmid was transformed into E. coli.

  15. Tebal Struktur Histologis Duodenum Ayam Pedaging yang Diberi Kombinasi Tylosin dan Gentamicin

    Directory of Open Access Journals (Sweden)

    I Gede Gilang Ikra Raditya

    2013-12-01

    Usaha ternak broiler, sejak tahun 1998 semakin menonjol perannya dalam mempersempit kesenjangan terhadap meningkatnya kebutuhan akan daging. Daging ayam broiler dipilih sebagai salah satu alternatif, karena kita tahu bahwa ayam broiler sangat efisen diproduksi. Tujuan dilakukan penelitian ini adalah untuk mengetahui tebal struktur histologis duodenum ayam yang diberi kombinasi tylosin dan gentamicin. Metode yang dipakai pada penelitian ini menggunakan 32 ayam pedaging yang di bagi dalam 4 kelompok yang di mana masing masing kelompok terbagi atas 8 ayam. Hasil penelitian ini sendiri adalah ketebalan struktur histologis duodenum pada kontrol (P0 rata-rata 7,2 ?m, perlakuan P1 rata-rata 7,2 ?m, perlakuan P2 rata-rata adalah 7,6 ?m, dan perlakuan P3 rata-rata adalah 7,9 ?m. P3 lebih tebal dari P2 dan P2 lebih besar dari P1 dan P0. Kesimpulan dari penelitian ini adalah kombinasi tylosin dan gentamicin ini efektif untuk menyeimbangkan flora normal yang ada di dalam duodenum sehingga membuat pertumbuhan ayam menjadi sempurna.

  16. Impairment of membrane phosphoinositide metabolism by aminoglycoside antibiotics: streptomycin, amikacin, kanamycin, dibekacin, gentamicin and neomycin.

    Science.gov (United States)

    Marche, P; Koutouzov, S; Girard, A

    1983-11-01

    Like many amphiphilic cationic drugs, aminoglycosides are able to produce phospholipidosis, mainly by inhibiting enzymes involved in phospholipid metabolism. Phosphoinositides have been suggested to function as receptors for aminoglycosides. Therefore, we investigated the influence of these drugs upon phosphoinositide metabolism by measuring the 32P-incorporation into the polyphosphoinositides, using the rat erythrocyte membrane as a model. Depending upon the experimental conditions, neomycin induced a decrease and/or an increase in the 32P-labeling of triphosphoinositides (TPI) and of diphosphoinositides (DPI), respectively. These variations were rapid and depended upon the drug concentration. At 0.3 mM, neomycin reversed the distribution of radioactivities associated with DPI and TPI without modifying the total radioactivity incorporated. This drug concentration altered neither the Mg++-activated TPI-specific phosphomonoesterase activity nor the Ca++-activated polyphosphoinositide phosphodiesterase activity. It appears likely that the drug inhibits the DPI-kinase activity, by interacting with DPI and thereby lowering the substrate availability. Over the range of concentrations studied (up to 1-2 mM), gentamicin, kanamycin and dibekacin behave as neomycin. However, their effects could be observed only at drug concentrations higher than those of neomycin. By contrast, streptomycin and amikacin did not alter the 32P-labeling of TPI and of DPI. The order of potency of aminoglycosides for the impairment of the phosphoinositide interconversion was neomycin, gentamicin, dibekacin, kanamycin. A possible relationship between the toxicity of aminoglycosides and their capacity to impair the phosphoinositide metabolism is discussed.

  17. Effect of n-Hexane extract of Nigella sativa on gentamicin-induced nephrotoxicity in rats

    Directory of Open Access Journals (Sweden)

    Nasim A Begum

    2006-03-01

    Full Text Available The present study investigated whether the administration of the n-hexane extract of the Nigella sativa Linn. (kalajira ameliorates gentamicin-induced nephrotoxicity in rats. Gentamicin (100 mg/kg/day for 7 days was administered and nephrotoxicity was evaluated biochemically (significantly decreased reduced glutathione in renal cortex and significantly increased serum creatinine and serum urea and histologically (moderate degree of proximal tubular damage. The n-hexane extract of N. sativa (5 ml/kg/day was administered as pre-, post- and concomitant treatment for 7 days in the nephrotoxic rats. Statistically significant amelioration in all the biochemical parameters supported by significantly improved renal cortical histology was observed in the n-hexane extract of N. sativa treated nephrotoxic rats, which was more evident in the post-treatment group than the pre- treatment and the concomitantly-treated group. It is suggested that some ingredients contained in the n-hexane extract of N. sativa effected in ameliorating the signs of nephrotoxicity and that the specific active principle of the n-hexane extract of N. sativa responsible for this amelioration if obtained, would be more useful.

  18. Protective Effects of Houttuynia cordata Thunb. on Gentamicin-induced Oxidative Stress and Nephrotoxicity in Rats.

    Science.gov (United States)

    Kang, Changgeun; Lee, Hyungkyoung; Hah, Do-Yun; Heo, Jung Ho; Kim, Chung Hui; Kim, Euikyung; Kim, Jong Shu

    2013-03-01

    Development of a therapy providing protection from, or reversing gentamicin-sulfate (GS)-induced oxidative stress and nephrotoxicity would be of great clinical significance. The present study was designed to investigate the protective effects of Houttuynia cordata Thunb. (HC) against gentamicin sulfate-induced renal damage in rats. Twenty-eight Sprague-Dawley rats were divided into 4 equal groups as follows: group 1, control; group 2, GS 100 mg/kg/d, intraperitoneal (i.p.) injection; group 3, GS 100 mg/kg/d, i.p. + HC 500 mg/kg/d, oral; and group 4, GS 100 mg/kg/d i.p. + HC 1000 mg/kg/d, oral administration). Treatments were administered once daily for 12 d. After 12 d, biochemical and histopathological analyses were conducted to evaluate oxidative stress and renal nephrotoxicity. Serum levels of creatinine, malondialdehyde (MDA), and blood urea nitrogen (BUN), together with renal levels of MDA, glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) were quantified to evaluate antioxidant activity. Animals treated with GS alone showed a significant increase in serum levels of creatinine, BUN, and MDA, with decreased renal levels of GSH, SOD, and CAT. Treatment of rats with HC showed significant improvement in renal function, presumably as a result of decreased biochemical indices and oxidative stress parameters associated with GS-induced nephrotoxicity. Histopathological examination of the rat kidneys confirmed these observations. Therefore, the novel natural antioxidant HC may protect against GSinduced nephrotoxicity and oxidative stress in rats.

  19. Application of Box-Behnken design to prepare gentamicin-loaded calcium carbonate nanoparticles.

    Science.gov (United States)

    Maleki Dizaj, Solmaz; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad-Hossein; Adibkia, Khosro

    2016-09-01

    The aim of this research was to prepare and optimize calcium carbonate (CaCO3) nanoparticles as carriers for gentamicin sulfate. A chemical precipitation method was used to prepare the gentamicin sulfate-loaded CaCO3 nanoparticles. A 3-factor, 3-level Box-Behnken design was used for the optimization procedure, with the molar ratio of CaCl2: Na2CO3 (X1), the concentration of drug (X2), and the speed of homogenization (X3) as the independent variables. The particle size and entrapment efficiency were considered as response variables. Mathematical equations and response surface plots were used, along with the counter plots, to relate the dependent and independent variables. The results indicated that the speed of homogenization was the main variable contributing to particle size and entrapment efficiency. The combined effect of all three independent variables was also evaluated. Using the response optimization design, the optimized Xl-X3 levels were predicted. An optimized formulation was then prepared according to these levels, resulting in a particle size of 80.23 nm and an entrapment efficiency of 30.80%. It was concluded that the chemical precipitation technique, together with the Box-Behnken experimental design methodology, could be successfully used to optimize the formulation of drug-incorporated calcium carbonate nanoparticles.

  20. PROTECTIVE EFFECT OF AQUEOUS AND METHANOLIC EXTRACTS OF LAGENARIA SICERARIA SEEDS IN GENTAMICIN INDUCED NEPHROTOXICITY

    Directory of Open Access Journals (Sweden)

    Mahurkar N.

    2012-06-01

    Full Text Available The aim of present study was to carry out the preliminary phytochemical studies and nephroprotective activity of metahanolic and aqueous extracts of Lagenaria siceraria seeds, family cucurbitaceae. These studies revealed the presence of flavonoids, tannins (ellagitannins, saponins, polyphenols, triterpenes, lagenin (protein in the extracts. The extract was found to be potent diuretic which causes excretion of sodium and potassium. Gentamicin is an extensively used aminolgycoside antibiotic. It has been reported to produce nephrotoxicity even at normal therapeutic dose level. Gentamicin was administrated intraperitonealy at a dose of 80mg/kg body weight for 9 days. The biochemical parameters viz. serum createnine, blood urea nitrogen (BUN and serum uric acid was found to be significantly increased whereas serum total protein was decreased. Histopathological sections showed marked glomerular, peritubular and blood vessel congestion. These increased levels of biochemical parameters and extent of renal damage were decreased by the methanolic and aqueous extracts of Lagenaria siceraria seeds at a dose of 250mg/kg, Cystone tab. (500mg/kg was used as reference standard to compare with the toxicant and test group animals.

  1. Increased expression of p38 mitogen- activated protein kinase is related to the acute renal lesions induced by gentamicin

    Directory of Open Access Journals (Sweden)

    Volpini R.A.

    2006-01-01

    Full Text Available Mitogen-activated protein kinases (MAPK may be involved in the pathogenesis of acute renal failure. This study investigated the expression of p-p38 MAPK and nuclear factor kappa B (NF-kappaB in the renal cortex of rats treated with gentamicin. Twenty rats were injected with gentamicin, 40 mg/kg, im, twice a day for 9 days, 20 with gentamicin + pyrrolidine dithiocarbamate (PDTC, an NF-kappaB inhibitor, 14 with 0.15 M NaCl, im, twice a day for 9 days, and 14 with 0.15 M NaCl , im, twice a day for 9 days and PDTC, 50 mg kg-1 day-1, ip, twice a day for 15 days. The animals were killed 5 and 30 days after the last of the injections and the kidneys were removed for histological, immunohistochemical and Western blot analysis and for nitrate determination. The results of the immunohistochemical study were evaluated by counting the p-p38 MAPK-positive cells per area of renal cortex measuring 0.05 mm². Creatinine was measured by the Jaffé method in blood samples collected 5 and 30 days after the end of the treatments. Gentamicin-treated rats presented a transitory increase in plasma creatinine levels. In addition, animals killed 5 days after the end of gentamicin treatment presented acute tubular necrosis and increased nitrate levels in the renal cortex. Increased expression of p-p38 MAPK and NF-kappaB was also observed in the kidneys from these animals. The animals killed 30 days after gentamicin treatment showed residual areas of interstitial fibrosis in the renal cortex, although the expression of p-p38 MAPK in their kidneys did not differ from control. Treatment with PDTC reduced the functional and structural changes induced by gentamicin as well as the expression of p-p38 MAPK and NF-kappaB. The increased expression of p-p38 MAPK and NF-kappaB observed in these rats suggests that these signaling molecules may be involved in the pathogenesis of tubulointerstitial nephritis induced by gentamicin.

  2. Intratympanic gentamicin treatment for Ménière's disease: A randomized, double-blind, placebo-controlled trial on dose efficacy - results of a prematurely ended study

    NARCIS (Netherlands)

    H.G. Bremer (Hendrik G.); I. van Rooy (Ingrid); B. Pullens (Bas); C. Colijn (Carla); I. Stegeman; H.J. van der Zaag-Loonen (Hester); P.P. van Benthem (Peter P.); S.F.L. Klis (Sjaak F L.); W. Grolman (Wilko); Tj.D. Bruintjes

    2014-01-01

    textabstractBackground: Gentamicin is used as a therapeutic agent for Ménière's disease because of its vestibulotoxicity causing chemo-ablation of the vestibular sensory epithelia. Its use has increased in recent years. However, there is still no consensus about the dose regimen of gentamicin in the

  3. Tissue reactions to bacteria-inoculated rat lead samples .2. Effect of local gentamicin release through surface-modified polyurethane tubing

    NARCIS (Netherlands)

    vanWachem, PB; vanLuyn, MJA; deWit, AW; Raatjes, D; Hendriks, M; Verhoeven, MLPM; Cahalan, PT

    1997-01-01

    A surface modification technique was developed to achieve controlled release of gentamicin from implanted polyurethane (PU) rat lead samples. PU tubing first was provided with an acrylic acid/acrylamide copolymer surface graft and then loaded with gentamicin. This surface modification technique resu

  4. Role of the electronegativity for the interface properties of non-polar heterostructures

    KAUST Repository

    Nazir, Safdar

    2012-04-01

    Density functional theory is used to investigate the interfaces in the non-polar ATiO 3/SrTiO 3 (A=Pb, Ca, Ba) heterostructures. All TiO 2-terminated interfaces show an insulating behavior. By reduction of the O content in the AO, SrO, and TiO 2 layers, metallic interface states develop, due to the occupation of the Ti 3d orbitals. For PbTiO 3/SrTiO 3, the Pb 6p states cross the Fermi energy. O vacancy formation energies depend strictly on the electronegativity and the effective volume of the A ion, while the main characteristics of the interface electronic states are maintained. © Europhysics Letters Association, 2012.

  5. Homoepitaxial HVPE-GaN growth on non-polar and semi-polar seeds

    Science.gov (United States)

    Amilusik, M.; Sochacki, T.; Lucznik, B.; Fijalkowski, M.; Smalc-Koziorowska, J.; Weyher, J. L.; Teisseyre, H.; Sadovyi, B.; Bockowski, M.; Grzegory, I.

    2014-10-01

    In this work homoepitaxial HVPE-GaN growth on non-polar and semi-polar GaN seeds was described. Two crystallization processes, in the same experimental conditions but using different carrier gases: N2 and H2, were performed. An influence of growth directions and growth conditions on the growth rate and properties (morphology, structural quality and oxygen and silicon contaminations) of obtained crystals were investigated and discussed. It was shown that the growth rate strongly depends on the growth direction and the carrier gas. It was demonstrated that for the semi-polar [20-21] direction it was possible to obtain high quality and highly conductive (without intentional doping) gallium nitride layers.

  6. Lipophilic polyelectrolyte gels as super-absorbent polymers for nonpolar organic solvents.

    Science.gov (United States)

    Ono, Toshikazu; Sugimoto, Takahiro; Shinkai, Seiji; Sada, Kazuki

    2007-06-01

    Polyelectrolyte gels that are known as super-absorbent polymers swell and absorb water up to several hundred times their dried weights and have become ubiquitous and indispensable materials in many applications. Their superior swelling abilities originate from the electrostatic repulsion between the charges on the polymer chains and the osmotic imbalance between the interior and exterior of the gels. However, no super-absorbent polymers for volatile organic compounds (VOCs), and especially for nonpolar organic solvents (epsilonpolymer networks. This expands the potential of polyelectrolytes that have been used only in aqueous solutions or highly polar solvents, and provides soft materials that swell in a variety of media. These materials could find applications as protective barriers for VOCs spilled in the environment and as absorbents for waste oil.

  7. ADSORPTION OF LATERALLY INTERACTING 1-NAPHTHOL/1-NAPHTHYL AMINE MIXTURES ON NONPOLAR SURFACES FROM AQUEOUS SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    Wei-ming Zhang; Jin-long Chen; Qun Chen; Ming-yang He; Bing-cai Pan; Quan-xing Zhang

    2006-01-01

    The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and 1-naphthylamine in all binary-component systems of different molar ratios were obviously higher than the corresponding uptakes predicted by the extended Langmuir model, assuming no interaction between the adsorbed molecules of the two components. This phenomenon was attributed to the cooperative adsorption effect arising from the hydrogen bonding interaction between 1-naphthol and 1-naphthylamine molecules. A modified extended Langmuir model was proposed to describe the binary adsorption behavior by means of introducing a fitting parameter related with the cooperative adsorption effect of the adsorbates.

  8. Variability of non-polar secondary metabolites in the red alga Portieria.

    Science.gov (United States)

    Payo, Dioli Ann; Colo, Joannamel; Calumpong, Hilconida; de Clerck, Olivier

    2011-01-01

    Possible sources of variation in non-polar secondary metabolites of Portieria hornemannii, sampled from two distinct regions in the Philippines (Batanes and Visayas), resulting from different life-history stages, presence of cryptic species, and/or spatiotemporal factors, were investigated. PCA analyses demonstrated secondary metabolite variation between, as well as within, five cryptic Batanes species. Intraspecific variation was even more pronounced in the three cryptic Visayas species, which included samples from six sites. Neither species groupings, nor spatial or temporal based patterns, were observed in the PCA analysis, however, intraspecific variation in secondary metabolites was detected between life-history stages. Male gametophytes (102 metabolites detected) were strongly discriminated from the two other stages, whilst female gametophyte (202 metabolites detected) and tetrasporophyte (106 metabolites detected) samples were partially discriminated. These results suggest that life-history driven variations, and possibly other microscale factors, may influence the variation within Portieria species.

  9. Variability of Non-Polar Secondary Metabolites in the Red Alga Portieria

    Directory of Open Access Journals (Sweden)

    Olivier de Clerck

    2011-11-01

    Full Text Available Possible sources of variation in non-polar secondary metabolites of Portieria hornemannii, sampled from two distinct regions in the Philippines (Batanes and Visayas, resulting from different life-history stages, presence of cryptic species, and/or spatiotemporal factors, were investigated. PCA analyses demonstrated secondary metabolite variation between, as well as within, five cryptic Batanes species. Intraspecific variation was even more pronounced in the three cryptic Visayas species, which included samples from six sites. Neither species groupings, nor spatial or temporal based patterns, were observed in the PCA analysis, however, intraspecific variation in secondary metabolites was detected between life-history stages. Male gametophytes (102 metabolites detected were strongly discriminated from the two other stages, whilst female gametophyte (202 metabolites detected and tetrasporophyte (106 metabolites detected samples were partially discriminated. These results suggest that life-history driven variations, and possibly other microscale factors, may influence the variation within Portieria species.

  10. On the rotational energy distributions of reactive, non-polar species in the interstellar medium

    CERN Document Server

    Glinski, Robert J; Downum, Clark R

    2013-01-01

    A basic model for the formation of non-equilibrium rotational energy distributions is described for reactive, homo-polar diatomic molecules and ions in the interstellar medium. Kinetic models were constructed to calculate the rotational populations of C2+ under the conditions it would experience in the diffuse interstellar medium. As the non-polar ion reacts with molecular hydrogen, but not atomic hydrogen, the thermalization of a hot nascent rotational population will be arrested by chemical reaction when the H2 density begins to be significant. Populations that deviate strongly from the local thermodynamic equilibrium are predicted for C2+ in environments where it may be detectable. Consequences of this are discussed and a new optical spectrum is calculated.

  11. Dynamics of electric field induced particle alignment in nonpolar polymer matrix

    Science.gov (United States)

    Tai, Xiangyang; Wu, Guozhang; Yui, Hiroshi; Asai, Shigeo; Sumita, Masao

    2003-11-01

    The dynamics of electric field induced particle alignment in nonpolar polymer matrix to build one-dimensional conductive materials was investigated. The influence of electric field on particle alignment was real-time traced by dynamic percolation measurement using carbon black (CB) filled polyethylene as a model system. The activation energy of the continuous CB path formation was calculated and found to be unchanged with CB alignment. The critical percolation concentration at thermodynamic equilibrium state φc* was deduced to characterize the anisotropism of network structure, by which the thermodynamic prerequisite electric field E* for the transition from three-dimensional isotropic network to one-dimensional chain could be easily found out.

  12. Application of classical thermodynamics to the conductivity in non-polar media

    Science.gov (United States)

    Gourdin-Bertin, S.; Chassagne, C.

    2016-06-01

    Electrical conductivity in non-polar media is a subject which recently regained interest. If most of experiments and theoretical developments were done more than 50 years ago, new experiments and theories have been recently published. As the electrical conductivity describes, at low field, the equilibrium state of a system, it is natural to apply theories based on equilibrium thermodynamics. In this article, well-established classical thermodynamics and solvations models are applied to recently published data. This enables to get a new insight in intriguing phenomena, such as the linear dependence of the conductivity on the concentration of ionic surfactant and the evaluation of conductivity for the mixture of two miscible fluids, such as alcohol and alcane, which have very different conductivities.

  13. Conditional probability analysis of multidrug resistance in Gram-negative bacilli isolated from tertiary medical institutions in South Korea during 1999-2009.

    Science.gov (United States)

    Kim, Yong-Hak

    2016-01-01

    Multidrug resistance of Gram-negative bacilli is a major problem globally. However, little is known about the combined probability of resistance to various antibiotics. In this study, minimum inhibitory concentrations of widely used antibiotics were determined using clinical isolates of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii, randomly chosen from strain collections created during 1999-2009 in tertiary medical institutions in Seoul, South Korea. To analyze combined efficacy of antibiotics against a subgroup of isolates, conditional probabilities were determined based on arbitrary, non-independent patterns of antimicrobial susceptibility and resistance. Multidrug resistance, defined as resistance to three or more classes of antibiotics, was observed in the following order: A. baumannii (96%), P. aeruginosa (65%), E. coli (52%), and K. pneumoniae (7%). A. baumannii strains resistant to gentamicin were found to be resistant to a number of antibiotics, except for colistin and polymyxin B. Resistance to gentamicin following exposure to this antibiotic was highly likely to lead to multidrug resistance in all four microbes. This study shows a causal relationship between gentamicin resistance and the prevalence of multidrug resistance in clinical isolates of Gramnegative bacilli in South Korea during 1999-2009 and suggests the importance of prudent use of gentamicin in hospitals.

  14. Antibiotic Resistance Pattern Of Bacterial Pathogens Isolated From Poultry Manure Used To Fertilize Fish Ponds In New Bussa, Nigeria

    Directory of Open Access Journals (Sweden)

    Funso Omojowo

    2013-02-01

    Full Text Available This study was carried out to isolate and identify antibiotic resistant bacteria from poultry manure usually used for pond fertilization. Poultry manure from 120 Chickens in National Institute for Freshwater Fisheries Research (NIFFR integrated fish farms, New-Bussa, Nigeria was collected. Five bacterial pathogens; Salmonella typhi, Escherichia coli, Shigella dysenteriae, Staphylococcus aureus and Aeromonas hydrophila were isolated. Antibiotic susceptibility testing carried out using the disk diffusion technique. Antibiotics used were; ofloxacin, amoxicillin, tetracycline, ampicillin, erythromycin, gentamicin, nalidixic acid and chloramphenicol. All the isolated organisms were 100% sensitive to ofloxacin. The multiple resistance pattern revealed that 100% were resistant to tetracycline, 84.34% resistant to ampicillin, 76.68% resistant to amoxicillin, 66% resistant to chloramphenicol, 66% resistant to gentamicin, 29% resistant to erythromycin, 28.34% resistant to nalidixic acid. The risk posed by untreated poultry manure used in fish pond fertilization and the public health implications of these results were discussed.

  15. Chronic toxicity and body residues of the nonpolar narcotic 1,2,3,4-tetrachrlorobenzene in Chironomus riparius

    NARCIS (Netherlands)

    Leslie, H.A.; Kraak, M.H.S.; Hermens, J.L.

    2004-01-01

    The use of internal concentrations as a dose parameter for baseline toxicity requires an understanding of the relationship between accumulation level and toxic effects, not only for acute but also for chronic exposure. In this study of chronic toxicity of the nonpolar narcotic 1,2,3,4-tetrachloroben

  16. Chronic toxicity and body residues of the nonpolar narcotic 1,2,3,4-tetrachrlorobenzene in Chironomus riparius

    NARCIS (Netherlands)

    Leslie, H.A.; Kraak, M.H.S.; Hermens, J.L.

    2004-01-01

    The use of internal concentrations as a dose parameter for baseline toxicity requires an understanding of the relationship between accumulation level and toxic effects, not only for acute but also for chronic exposure. In this study of chronic toxicity of the nonpolar narcotic

  17. Evaluation of Extraction Protocols for Simultaneous Polar and Non-Polar Yeast Metabolite Analysis Using Multivariate Projection Methods

    Directory of Open Access Journals (Sweden)

    Nicolas P. Tambellini

    2013-07-01

    Full Text Available Metabolomic and lipidomic approaches aim to measure metabolites or lipids in the cell. Metabolite extraction is a key step in obtaining useful and reliable data for successful metabolite studies. Significant efforts have been made to identify the optimal extraction protocol for various platforms and biological systems, for both polar and non-polar metabolites. Here we report an approach utilizing chemoinformatics for systematic comparison of protocols to extract both from a single sample of the model yeast organism Saccharomyces cerevisiae. Three chloroform/methanol/water partitioning based extraction protocols found in literature were evaluated for their effectiveness at reproducibly extracting both polar and non-polar metabolites. Fatty acid methyl esters and methoxyamine/trimethylsilyl derivatized aqueous compounds were analyzed by gas chromatography mass spectrometry to evaluate non-polar or polar metabolite analysis. The comparative breadth and amount of recovered metabolites was evaluated using multivariate projection methods. This approach identified an optimal protocol consisting of 64 identified polar metabolites from 105 ion hits and 12 fatty acids recovered, and will potentially attenuate the error and variation associated with combining metabolite profiles from different samples for untargeted analysis with both polar and non-polar analytes. It also confirmed the value of using multivariate projection methods to compare established extraction protocols.

  18. Giant tunneling electroresistance induced by ferroelectrically switchable two-dimensional electron gas at nonpolar BaTiO3/SrTiO3 interface

    Science.gov (United States)

    Wu, Qingyun; Shen, Lei; Yang, Ming; Zhou, Jun; Chen, Jingsheng; Feng, Yuan Ping

    2016-10-01

    Using first-principles calculations, we investigate the tunneling electroresistance (TER) of ferroelectric tunnel junctions [Pt /BaTiO3(BTO)/SrTiO3(STO )/Pt ]. It is found that the TER of Pt/BTO/STO/Pt junctions can be greatly increased with increasing thickness of STO layers. The underlying physics of this giant TER is the switchable two-dimensional electron gas (2DEG) at a nonpolar BTO/STO interface induced by the ferroelectric polarization. Our calculations show that when the ferroelectric polarization is pointing from BTO to STO, a 2DEG forms at the interface and acts as bridge for electrons to tunnel through the junctions. Nevertheless, there is no 2DEG at the interface under the opposite direction of the ferroelectric polarization, which results in a large tunnel resistance. More importantly, this ferroelectrically switchable 2DEG leads to a low resistance area product for Pt/BTO/STO/Pt junctions, which offers good compatibility with other components in an integrated circuit and is highly desired for industrial applications.

  19. Non-polar lipids accumulate during storage of transfusion products and do not contribute to the onset of transfusion-related acute lung injury.

    Science.gov (United States)

    Peters, A L; Vervaart, M A T; van Bruggen, R; de Korte, D; Nieuwland, R; Kulik, W; Vlaar, A P J

    2017-01-01

    The accumulation of non-polar lipids arachidonic acid, 5-hydroxyeicosatetraenoic acid (HETE), 12-HETE and 15-HETE during storage of transfusion products may play a role in the onset of transfusion-related acute lung injury (TRALI), a syndrome of respiratory distress after transfusion. We investigated non-polar lipid accumulation in red blood cells (RBCs) stored for 42 days, plasma stored for 7 days at either 4 or 20°C and platelet (PLT) transfusion products stored for 7 days. Furthermore, we investigated whether transfusion of RBCs with increased levels of non-polar lipids induces TRALI in a 'two-hit' human volunteer model. All products were produced following Dutch Blood Bank protocols and are according to European standards. Non-polar lipids were measured with high-performance liquid chromotography followed by mass spectrometry. All non-polar lipids increased in RBCs after 21 days of storage compared to baseline. The non-polar lipid concentration in plasma increased significantly, and the increase was even more pronounced in products stored at 20°C. In platelets, baseline levels of 5-HETE and 15-HETE were higher than in RBCs or plasma. However, the non-polar lipids did not change significantly during storage of PLT products. Infusion of RBCs with increased levels of non-polar lipids did not induce TRALI in LPS-primed human volunteers. We conclude that non-polar lipids accumulate in RBC and plasma transfusion products and that accumulation is temperature dependent. Accumulation of non-polar lipids does not appear to explain the onset of TRALI (Dutch Trial Register - NTR4455). © 2016 International Society of Blood Transfusion.

  20. Role of somatostatin receptor-2 in gentamicin-induced auditory hair cell loss in the Mammalian inner ear.

    Directory of Open Access Journals (Sweden)

    Yves Brand

    Full Text Available Hair cells and spiral ganglion neurons of the mammalian auditory system do not regenerate, and their loss leads to irreversible hearing loss. Aminoglycosides induce auditory hair cell death in vitro, and evidence suggests that phosphatidylinositol-3-kinase/Akt signaling opposes gentamicin toxicity via its downstream target, the protein kinase Akt. We previously demonstrated that somatostatin-a peptide with hormone/neurotransmitter properties-can protect hair cells from gentamicin-induced hair cell death in vitro, and that somatostatin receptors are expressed in the mammalian inner ear. However, it remains unknown how this protective effect is mediated. In the present study, we show a highly significant protective effect of octreotide (a drug that mimics and is more potent than somatostatin on gentamicin-induced hair cell death, and increased Akt phosphorylation in octreotide-treated organ of Corti explants in vitro. Moreover, we demonstrate that somatostatin receptor-1 knockout mice overexpress somatostatin receptor-2 in the organ of Corti, and are less susceptible to gentamicin-induced hair cell loss than wild-type or somatostatin-1/somatostatin-2 double-knockout mice. Finally, we show that octreotide affects auditory hair cells, enhances spiral ganglion neurite number, and decreases spiral ganglion neurite length.

  1. Development of a standardized susceptibility test for Campylobacter with quality control ranges for ciprofloxacin, doxycycline, erythromycin, gentamicin, and meropenem

    DEFF Research Database (Denmark)

    McDermott, P. F.; Bodeis, S. M.; Aarestrup, Frank Møller

    2004-01-01

    -control (QC) strain. Minimal inhibitory concentration (MIC) QC ranges were determined for two incubation time/temperature combinations: 36degreesC for 48 hr and 42degreesC for 24 hr. Quality-control ranges were determined for ciprofloxacin, doxycycline, erythromycin, gentamicin, and meropenem. For all...

  2. Neamin as an immunogen for the development of a generic ELISA detecting gentamicin, kanamycin and neomycin in milk

    NARCIS (Netherlands)

    Loomans, E.E.M.G.; Wiltenburg, van J.; Koets, M.; Amerongen, van A.

    2003-01-01

    A broad-specific ELISA using one antibody preparation for the detection of gentamicin, kanamycin, and neomycin in milk is reported for the first time. For the immunization of rabbits, neamin was used as the generic hapten on the basis of the facts that it is a two-ring fragment of neomycin and, in s

  3. Continuous intravenous infusion of ampicillin and gentamicin during parenteral nutrition to 36 newborn infants using a dosage schedule

    DEFF Research Database (Denmark)

    Colding, H; Møller, S; Andersen, G E

    1984-01-01

    Ampicillin and gentamicin were given continuously i.v. to 36 newborn infants using a dosage schedule and the results were compared with those obtained in an earlier study including 88 infants who received individually calculated dosages. With the dosage schedule the variation in the serum concent...

  4. Beetroot (Beta vulgaris L. Extract Ameliorates Gentamicin-Induced Nephrotoxicity Associated Oxidative Stress, Inflammation, and Apoptosis in Rodent Model

    Directory of Open Access Journals (Sweden)

    Ali A. El Gamal

    2014-01-01

    Full Text Available The present investigation was designed to investigate the protective effect of (Beta vulgaris L. beat root ethanolic extract (BVEE on gentamicin-induced nephrotoxicity and to elucidate the potential mechanism. Serum specific kidney function parameters (urea, uric acid, total protein, creatinine, and histopathology of kidney tissue were evaluated to access gentamicin-induced nephrotoxicity. The oxidative/nitrosative stress (Lipid peroxidation, MDA, NP-SH, Catalase, and nitric oxide levels was assessed. The inflammatory response (TNF-α, IL-6, MPO, NF-κB (p65, and NF-κB (p65 DNA binding and apoptotic marker (Caspase-3, Bax, and Bcl-2 were also evaluated. BVEE (250 and 500 mg/kg treatment along with gentamicin restored/increased the renal endogenous antioxidant status. Gentamicin-induced increased renal inflammatory cytokines (TNF-α and IL-6, nuclear protein expression of NF-κB (p65, NF-κB-DNA binding activity, myeloperoxidase (MPO activity, and nitric oxide level were significantly down regulated upon BVEE treatment. In addition, BVEE treatment significantly reduced the amount of cleaved caspase 3 and Bax, protein expression and increased the Bcl-2 protein expression. BVEE treatment also ameliorated the extent of histologic injury and reduced inflammatory infiltration in renal tubules. These findings suggest that BVEE treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress, inflammation, and apoptosis in the kidney.

  5. Biochemical assessment of nephroprotective and nephrocurative activity of Withania somnifera on gentamicin induced nephrotoxicity in experimental rats

    Directory of Open Access Journals (Sweden)

    Vimlesh Kushwaha

    2016-01-01

    Results: BUN and serum creatinine values were significantly low as compared to GT group in all test duration in phase-1. In phase two there was no significant difference of these markers in two groups. Conclusions: Withania Somnifera root extract have nephroprotective activity against gentamicin induced nephrotoxicity. [Int J Res Med Sci 2016; 4(1.000: 298-302

  6. Neamin as an immunogen for the development of a generic ELISA detecting gentamicin, kanamycin and neomycin in milk

    NARCIS (Netherlands)

    Loomans, E.E.M.G.; Wiltenburg, van J.; Koets, M.; Amerongen, van A.

    2003-01-01

    A broad-specific ELISA using one antibody preparation for the detection of gentamicin, kanamycin, and neomycin in milk is reported for the first time. For the immunization of rabbits, neamin was used as the generic hapten on the basis of the facts that it is a two-ring fragment of neomycin and, in s

  7. Synthesis and characterization of a novel controlled release zinc oxide/gentamicin-chitosan composite with potential applications in wounds care.

    Science.gov (United States)

    Vasile, Bogdan Stefan; Oprea, Ovidiu; Voicu, Georgeta; Ficai, Anton; Andronescu, Ecaterina; Teodorescu, Andrei; Holban, Alina

    2014-03-25

    Freshly prepared ZnO nanoparticles were incorporated into a chitosan solution in weight ratios ranging from 1:1 to 12:1. Starting from the ratio of 3:1 the chitosan solution was transformed into a gel with a high consistency, which incorporates 15mL water for only 0.1g solid substance. The powders obtained after drying the gel were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermal analysis (TG-DSC). The electronic (UV-vis), infrared (FTIR) and photoluminescence (PL) spectra were also recorded. ZnO particles were coated with gentamicin and incorporated into the chitosan matrix, to yield a ZnO/gentamicin-chitosan gel. The release rate of gentamicin was monitored photometrically. This ZnO/gentamicin-chitosan gel proved great antimicrobial properties, inhibiting Staphylococcus aureus and Pseudomonas aeruginosa growth in both planktonic and surface-attached conditions. The results indicate that the obtained composite can be used in cutaneous healing for developing improved wound dressings, which combine the antibacterial activity of all three components with the controlled release of the antibiotic. This wound dressing maintains a moist environment at the wound interface, providing a cooling sensation and soothing effect, while slowly releasing the antibiotic. The system is fully scalable to any other soluble drug, as the entire solution remains trapped in the ZnO-chitosan gel.

  8. Continuous intravenous infusion of ampicillin and gentamicin during parenteral nutrition to 36 newborn infants using a dosage schedule

    DEFF Research Database (Denmark)

    Colding, H; Møller, S; Andersen, G E

    1984-01-01

    Ampicillin and gentamicin were given continuously i.v. to 36 newborn infants using a dosage schedule and the results were compared with those obtained in an earlier study including 88 infants who received individually calculated dosages. With the dosage schedule the variation in the serum concent...

  9. Effects of the sol-gel route on the structural characteristics and antibacterial activity of silica-encapsulated gentamicin.

    Science.gov (United States)

    Corrêa, G G; Morais, E C; Brambilla, R; Bernardes, A A; Radtke, C; Dezen, D; Júnior, A V; Fronza, N; Santos, J H Z Dos

    2014-04-01

    The effects of sol-gel processes, i.e., acid-catalyzed gelation, base-catalyzed gelation and base-catalyzed precipitation routes, on the encapsulation of gentamicin were investigated. The resulting xerogels were characterized using a series of complementary instrumental techniques, i.e., the adsorption/desorption of nitrogen, small-angle X-ray scattering, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. The encapsulated gentamicin samples were tested against a series of Gram-positive and Gram-negative bacterial strains. The best antimicrobial activity was observed with the encapsulated gentamicin that was prepared via the precipitation route, even in comparison with the neat antibiotic, especially in the case of the Gram-positive strain Staphylococcus aureus. The gentamicin concentration on the outermost surface and the zeta potential were identified as factors that affected the highest efficiency, as observed in the case of encapsulation via the base-catalyzed process.

  10. Local Application of Gentamicin in the Prophylaxis of Perineal Wound Infection after Abdominoperineal Resection: A Systematic Review

    NARCIS (Netherlands)

    G.D. Musters (Gijsbert D.); J.W.A. Burger (Jacobus); C.J. Buskens (Christianne); W.A. Bemelman; P.J. Tanis (Pieter)

    2015-01-01

    textabstractBackground: Use of topical antibiotics to improve perineal wound healing after abdominoperineal resection (APR) is controversial. The aim of this systematic review was to determine the impact of local application of gentamicin on perineal wound healing after APR. Methods: The electronic

  11. Protective effects of the aqueous leaf extract of Aloe barbadensis on gentamicin and cisplatin-induced nephrotoxic rats

    Institute of Scientific and Technical Information of China (English)

    Paoulomi Chatterjee﹡; Aniruddha Mukherjee; Subhangkar Nandy

    2012-01-01

    Objective: To study the protective effects of the aqueous leaf extract of Aloe barbadensis (AEAB) on gentamicin and Cisplatin-induced nephrotoxic Wistar rats. Methods: In each model of nephrotoxicity, thirty adult male Wistar rats were evenly divided into 5 groups. Groups I and II served as untreated and model controls, respectively while groups III-V were the treatment groups which were pretreated with 100-200 mg/kg bodyweight per day of AEAB 1 h before each dose of the nephrotoxicants. On the 8th day(in case of gentamicin) and on 6th day(in case of Cisplatin), blood samples for serum urea, total protein and creatinine as well as some ions like sodium, potassium, chloride and uric acid while the rat kidneys for histology were obtained under inhaled diethyl ether anesthesia. Results: In the gentamicin nephrotoxic rats, 100-200 mg/kg bodyweight per day significantly attenuated elevations in the serum creatinine, total protein and blood urea nitrogen levels in dose related fashion and no treatment related effect on uric acid and ions, and attenuated the gentamicin-induced tubulonephrosis. Similar effects were also recorded in the Cisplatin model of acute renal injury. Conclusions:The nephroprotective effect of AEAB could be due to the inherent antioxidant and free-radical-scavenging principle(s) contained in the extract.In the near future, AEAB could constitute a lead to discovery of a novel drug for the treatment of drug-induced nephrotoxicity.

  12. Extended-Interval Dosing of Gentamicin Aiming for a Drug-Free Period in Neonates: A Prospective Cohort Study.

    NARCIS (Netherlands)

    van Maarseveen, Erik M; Sprij, Arwen; Touw, Daniel J

    2016-01-01

    BACKGROUND Current gentamicin dosing algorithms in adult populations target a high peak concentration (Cmax) assuring efficacy and a drug-free period (concentration 8 mg·L and estimated trough concentrations 8 mg·L with a Cmin value

  13. Extended-Interval Dosing of Gentamicin Aiming for a Drug-Free Period in Neonates : A Prospective Cohort Study

    NARCIS (Netherlands)

    van Maarseveen, Erik M.; Sprij, Arwen; Touw, Daniel J.

    2016-01-01

    Background:Current gentamicin dosing algorithms in adult populations target a high peak concentration (C-max) assuring efficacy and a drug-free period (concentration 8 mgL(-1) and estimated trough concentrations 8 mgL(-1) with a C-min value

  14. Automatic parametrization of non-polar implicit solvent models for the blind prediction of solvation free energies

    Science.gov (United States)

    Wang, Bao; Zhao, Zhixiong; Wei, Guo-Wei

    2016-09-01

    In this work, a systematic protocol is proposed to automatically parametrize the non-polar part of implicit solvent models with polar and non-polar components. The proposed protocol utilizes either the classical Poisson model or the Kohn-Sham density functional theory based polarizable Poisson model for modeling polar solvation free energies. Four sets of radius parameters are combined with four sets of charge force fields to arrive at a total of 16 different parametrizations for the polar component. For the non-polar component, either the standard model of surface area, molecular volume, and van der Waals interactions or a model with atomic surface areas and molecular volume is employed. To automatically parametrize a non-polar model, we develop scoring and ranking algorithms to classify solute molecules. The their non-polar parametrization is obtained based on the assumption that similar molecules have similar parametrizations. A large database with 668 experimental data is collected and employed to validate the proposed protocol. The lowest leave-one-out root mean square (RMS) error for the database is 1.33 kcal/mol. Additionally, five subsets of the database, i.e., SAMPL0-SAMPL4, are employed to further demonstrate that the proposed protocol. The optimal RMS errors are 0.93, 2.82, 1.90, 0.78, and 1.03 kcal/mol, respectively, for SAMPL0, SAMPL1, SAMPL2, SAMPL3, and SAMPL4 test sets. The corresponding RMS errors for the polarizable Poisson model with the Amber Bondi radii are 0.93, 2.89, 1.90, 1.16, and 1.07 kcal/mol, respectively.

  15. An experimental design approach to the preparation of pegylated polylactide-co-glicolide gentamicin loaded microparticles for local antibiotic delivery

    Energy Technology Data Exchange (ETDEWEB)

    Dorati, Rossella; DeTrizio, Antonella; Genta, Ida; Grisoli, Pietro; Merelli, Alessia [Department of Drug Sciences, Viale Taramelli 12, University of Pavia, 27100, Pavia (Italy); Tomasi, Corrado [IENI CNR Lecco Unit, Via Promessi Sposi 29, 23900, Lecco (Italy); Conti, Bice, E-mail: bice.conti@unipv.it [Department of Drug Sciences, Viale Taramelli 12, University of Pavia, 27100, Pavia (Italy)

    2016-01-01

    The present paper takes into account the DOE application to the preparation process of biodegradable microspheres for osteomyelitis local therapy. With this goal gentamicin loaded polylactide-co-glycolide-co-polyethyleneglycol (PLGA-PEG) microspheres were prepared and investigated. Two preparation protocols (o/w and w/o/w) with different process conditions, and three PLGA-PEG block copolymers with different compositions of lactic and glycolic acids and PEG, were tested. A Design Of Experiment (DOE) screening design was applied as an approach to scale up manufacturing step. The results of DOE screening design confirmed that w/o/w technique, the presence of salt and the 15%w/v polymer concentration positively affected the EE% (72.1–97.5%), and span values of particle size distribution (1.03–1.23), while salt addition alone negatively affected the yield process. Process scale up resulted in a decrease of gentamicin EE% that can be attributed to the high volume of water used to remove PVA and NaCl residues. The results of in vitro gentamicin release study show prolonged gentamicin release up to three months from the microspheres prepared with salt addition in the dispersing phase; the behavior being consistent with their highly compact structure highlighted by scanning electron microscopy analysis. The prolonged release of gentamicin is maintained even after embedding the biodegradable microspheres into a thermosetting composite gel made of chitosan and acellular bovine bone matrix (Orthoss® granules), and the microbiologic evaluation demonstrated the efficacy of the gentamicin loaded microspheres on Escherichia coli. The collected results confirm the feasibility of the scale up of microsphere manufacturing process and the high potential of the microparticulate drug delivery system to be used for the local antibiotic delivery to bone. - Highlights: • To get a more effective therapy for the prevention and treatment of osteomyelitis. • To exploit the local

  16. Effects of neuroactive steroids on cochlear hair cell death induced by gentamicin.

    Science.gov (United States)

    Nakamagoe, Mariko; Tabuchi, Keiji; Nishimura, Bungo; Hara, Akira

    2011-12-11

    As neuroactive steroids, sex steroid hormones have non-reproductive effects. We previously reported that 17β-estradiol (βE2) had protective effects against gentamicin (GM) ototoxicity in the cochlea. In the present study, we examined whether the protective action of βE2 on GM ototoxicity is mediated by the estrogen receptor (ER) and whether other estrogens (17α-estradiol (αE2), estrone (E1), and estriol (E3)) and other neuroactive steroids, dehydroepiandrosterone (DHEA) and progesterone (P), have similar protective effects. The basal turn of the organ of Corti was dissected from Sprague-Dawley rats and cultured in a medium containing 100 μM GM for 48h. The effects of βE2 and ICI 182,780, a selective ER antagonist, were examined. In addition, the effects of other estrogens, DHEA and P were tested using this culture system. Loss of outer hair cells induced by GM exposure was compared among groups. βE2 exhibited a protective effect against GM ototoxicity, but its protective effect was antagonized by ICI 182,780. αE2, E1, and E3 also protected hair cells against gentamicin ototoxicity. DHEA showed a protective effect; however, the addition of ICI 182,780 did not affect hair cell loss. P did not have any effect on GM-induced outer hair cell death. The present findings suggest that estrogens and DHEA are protective agents against GM ototoxicity. The results of the ER antagonist study also suggest that the protective action of βE2 is mediated via ER but that of DHEA is not related to its conversion to estrogen and binding to ER. Further studies on neuroactive steroids may lead to new insights regarding cochlear protection.

  17. Protective effect of selenium on gentamicin-induced oxidative stress and nephrotoxicity in rats.

    Science.gov (United States)

    Randjelovic, Pavle; Veljkovic, Slavimir; Stojiljkovic, Nenad; Velickovic, Ljubinka; Sokolovic, Dusan; Stoiljkovic, Milan; Ilic, Ivan

    2012-04-01

    Gentamicin (GM) is a widely used antibiotic against serious, life-threatening infections, but its usefulness is limited by the development of nephrotoxicity. The present study was designed to determine the protective effect of selenium (Se) in GM-induced nephrotoxicity in rats. Experiments were done on 32 adult Wistar rats divided into four groups of 8 animals each. The GM group received gentamicin (100 mg/kg), whereas the GM+Se group received the same dose of GM and selenium (1 mg/kg) by intraperitoneal (i.p.) injections on a daily basis. Animals in the Se group, serving as a positive control, received only selenium (1 mg/kg) and the control group received saline (1 mL/day), both given i.p. All groups were treated during 8 consecutive days. Quantitative evaluation of GM-induced structural alterations and degree of functional alterations in the kidneys were performed by histopathological and biochemical analyses in order to determine potential beneficial effects of selenium coadministration with GM. GM was observed to cause a severe nephrotoxicity, which was evidenced by an elevation of serum urea and creatinine levels. The significant increases in malondialdehyde levels and protein carbonyl groups indicated that GM-induced tissue injury was mediated through oxidative reactions. On the other hand, simultaneous selenium administration protected kidney tissue against oxidative damage and the nephrotoxic effect caused by GM treatment. Exposure to GM caused necrosis of tubular epithelial cells. Necrosis of tubules was found to be prevented by selenium pretreatment. The results from our study indicate that selenium supplementation attenuates oxidative-stress-associated renal injury by reducing oxygen free radicals and lipid peroxidation in GM-treated rats.

  18. Ampicillin and gentamicin are a useful first-line combination for the management of sepsis in under-five children at an urban hospital in Bangladesh.

    Science.gov (United States)

    Bibi, Samira; Chisti, Mohammod Jobayer; Akram, Farhana; Pietroni, Mark A C

    2012-12-01

    The study evaluated the commonly-used drugs for the management of sepsis and their outcome among under-five children. We evaluated the hospital-records of all paediatric sepsis patients (n = 183) in the intensive care unit (ICU) and longer-stay unit (LSU) of the Dhaka Hospital of icddr,b. These records were collected from the hospital management system (SHEBA) during November 2009 to October 2010. A total of 183 under-five children with clinical sepsis were found during the study period, and 14 (8%) of them were neonates. One hundred and eighty-one patients had received a combination of injection ampicilin and injection gentamicin, and two patients had received the combination of injection ceftriaxone and injection gentamicin. Only 46 (25%) patients required a change of antibiotics to the combination of intravenous ceftriaxone plus gentamicin after non-response of injection ampicilin and injection gentamicin combination; 7/181 (4%) patients died who received injection ampicilin and injection gentamicin whereas none died among the other two patients who received injection ceftriaxone and injection gentamicin (p = 1.00). The combination of injection ampicilin and injection gentamicin as the first-line antibiotics for the management of sepsis in children even beyond the neonatal age is very effective, resulting in lower mortality.

  19. In vitro gentamicin release from commercially available calcium-phosphate bone substitutes influence of carrier type on duration of the release profile

    Directory of Open Access Journals (Sweden)

    Bronckers Antonius LJJ

    2006-02-01

    Full Text Available Abstract Background Polymethyl-methacrylate (PMMA beads releasing antibiotics are used extensively to treat osteomyelitis, but require surgical removal afterwards because they do not degrade. Methods As an alternative option, this report compares the in vitro gentamicin release profile from clinically used, biodegradable carrier-materials: six injectable cements and six granule-types. Cement cylinders and coated granules containing 3% gentamicin were submerged in dH2O and placed in a 48-sample parallel drug-release system. At regular intervals (30, 90, 180 min. and then every 24 h, for 21 days, the release fluid was exchanged and the gentamicin concentration was measured. The activity of released gentamicin was tested on Staphylococcus aureus. Results All combinations showed initial burst-release of active gentamicin, two cements had continuous-release (17 days. The relative release of all cements (36–85% and granules (30–62% was higher than previously reported for injectable PMMA-cements (up to 17% and comparable to other biodegradable carriers. From the cements residual gentamicin could be extracted, whereas the granules released all gentamicin that had adhered to the surface. Conclusion The high release achieved shows great promise for clinical application of these biodegradable drug-carriers. Using the appropriate combination, the required release profile (burst or sustained may be achieved.

  20. Antimicrobial resistance and in vitro biofilm-forming ability of enterococci from intensive and extensive farming broilers.

    Science.gov (United States)

    Oliveira, M; Santos, V; Fernandes, A; Bernardo, F; Vilela, C L

    2010-05-01

    Enterococci, major broiler intestinal colonizers, play a recognized role in antimicrobial resistance transmission. Several virulence mechanisms, such as biofilm expression, have been identified. Minimum inhibitory concentrations of vancomycin, enrofloxacin, oxytetracycline, streptomycin, and gentamicin and biofilm production of 34 isolates from intensive and extensive farming system broilers were evaluated. All isolates were susceptible to vancomycin. In extensive-reared broilers (n = 18), resistance to enrofloxacin, oxytetracycline, streptomycin, and gentamicin was high (83.33, 55.56, 100, and 83.33%, respectively). Intensive farming broilers (n = 16) showed a lower resistance level for enrofloxacin and streptomycin and a higher resistance level for oxytetracycline and gentamicin. The relation between antimicrobial susceptibility and farming system was not significant for all drugs tested (P > or = 0.05). Enterococci produced biofilm at 24 h (47.0%), 48 h (55.9%), and 72 h (58.8%). Resistance to gentamicin and streptomycin was related to biofilm production at all time points (P or = 0.05). Poultry are colonized by biofilm-producing and antimicrobial-resistant enterococci, independently of the farming system. Results show a relation between resistance to the majority of the drugs tested and biofilm production, which reenforces the importance of these virulence factors in animal and public health.

  1. Heme and non-heme iron transporters in non-polarized and polarized cells

    Directory of Open Access Journals (Sweden)

    Yasui Yumiko

    2010-06-01

    Full Text Available Abstract Background Heme and non-heme iron from diet, and recycled iron from hemoglobin are important products of the synthesis of iron-containing molecules. In excess, iron is potentially toxic because it can produce reactive oxygen species through the Fenton reaction. Humans can absorb, transport, store, and recycle iron without an excretory system to remove excess iron. Two candidate heme transporters and two iron transporters have been reported thus far. Heme incorporated into cells is degraded by heme oxygenases (HOs, and the iron product is reutilized by the body. To specify the processes of heme uptake and degradation, and the reutilization of iron, we determined the subcellular localizations of these transporters and HOs. Results In this study, we analyzed the subcellular localizations of 2 isoenzymes of HOs, 4 isoforms of divalent metal transporter 1 (DMT1, and 2 candidate heme transporters--heme carrier protein 1 (HCP1 and heme responsive gene-1 (HRG-1--in non-polarized and polarized cells. In non-polarized cells, HCP1, HRG-1, and DMT1A-I are located in the plasma membrane. In polarized cells, they show distinct localizations: HCP1 and DMT1A-I are located in the apical membrane, whereas HRG-1 is located in the basolateral membrane and lysosome. 16Leu at DMT1A-I N-terminal cytosolic domain was found to be crucial for plasma membrane localization. HOs are located in smooth endoplasmic reticulum and colocalize with NADPH-cytochrome P450 reductase. Conclusions HCP1 and DMT1A-I are localized to the apical membrane, and HRG-1 to the basolateral membrane and lysosome. These findings suggest that HCP1 and DMT1A-I have functions in the uptake of dietary heme and non-heme iron. HRG-1 can transport endocytosed heme from the lysosome into the cytosol. These localization studies support a model in which cytosolic heme can be degraded by HOs, and the resulting iron is exported into tissue fluids via the iron transporter ferroportin 1, which is

  2. Properties of Achromobacter xylosoxidans highly resistant to aminoglycoside antibiotics.

    Science.gov (United States)

    Nakamoto, Sachiko; Goda, Natsumi; Hayabuchi, Tatsuya; Tamaki, Hiroo; Ishida, Ayami; Suzuki, Ayaka; Nakano, Kaori; Yui, Shoko; Katsumata, Yuto; Yamagami, Yuki; Burioka, Naoto; Chikumi, Hiroki; Shimizu, Eiji

    2016-04-01

    We herein discovered a highly resistant clinical isolate of Pseudomonas aeruginosa with MICs to amikacin, gentamicin, and arbekacin of 128 μg/mL or higher in a drug sensitivity survey of 92 strains isolated from the specimens of Yoka hospital patients between January 2009 and October 2010, and Achromobacter xylosoxidans was separated from this P. aeruginosa isolate. The sensitivity of this bacterium to 29 antibiotics was investigated. The MICs of this A. xylosoxidans strain to 9 aminoglycoside antibiotics were: amikacin, gentamicin, arbekacin, streptomycin, kanamycin, neomycin, and spectinomycin, 1,024 μg/mL or ≥ 1,024 μg/mL; netilmicin, 512 μg/mL; and tobramycin, 256 μg/mL. This strain was also resistant to dibekacin. This aminoglycoside antibiotic resistant phenotype is very rare, and we are the first report the emergence of A. xylosoxidans with this characteristic.

  3. "Emergence of Multidrug Resistant Strains of Escherichia coli Isolated from Urinary Tract Infections"

    OpenAIRE

    R Moniri; Khorshidi, A; H Akbari

    2003-01-01

    The emergence of multidrug resistant strains of Escherichia coli has complicated treatment decision and may lead to treatment failures. From April to November 2001 we prospectively evaluated the prevalence of resistance to trimethoprim-sulfamethoxazole (SXT), gentamicin, cephalothin, ciprofloxacin, and nitrofurantoin in 220 Escherichia coli isolates from patients with urinary tract infections in kashan, Iran. To assess the current breadth of multidrug resistance among urinary isolates of E. c...

  4. Aminoglycoside-Resistant Mutation of Pseudomonas aeruginosa Defective in Cytochrome c552 and Nitrate Reductase

    OpenAIRE

    Bryan, L E; Nicas, Thalia; Holloway, B W; Crowther, Carol

    1980-01-01

    A gentamicin-resistant mutant of Pseudomonas aeruginosa PAO503 was selected after ethyl methane sulfonate mutagenesis. The strain, P. aeruginosa PAO2401 had increased resistance to all aminoglycosides tested but exhibited no change for other antibiotics. The mutation designated aglA (aminoglycoside resistance) was 50% cotransducible with the 8-min ilvB,C marker on the P. aeruginosa chromosome. It showed a marked reduction in cytochrome c552 and nitrate reductase (Nar) and a change in terminal...

  5. Remarks on energetic conditions for positronium formation in non-polar solids. Coupled Dipole Method application

    CERN Document Server

    Pietrow, Marek

    2015-01-01

    A numerical program calculating an energy of a positron or (and) an electron near the free volume in solid n-alkanes has been build. The theory of interaction of e+ or (and) e- with this non-polar media based on polarizability has been introduced. The energy of the e+ -- e- pair in the bulk was compared to that calculated when the pair forms a positronium (Ps) inside the free volume. The calculations are based on the Coupled Dipole Method and the dipole-dipole interaction energy for induced dipoles is taken into account. Furthermore, a correction of a local permittivity for the e+ -- e- interaction is calculated taking into account the non-isotropic medium between them. The method is a step toward more accurate calculations of energetic conditions during the Ps formation in matter. The possibility of emission of the excess energy of the Ps formation as electromagnetic radiation is discussed. It is argued that if this radiation is observed, it can be used as a new spectroscopic tool providing information about...

  6. Nonpolarized signaling reveals two distinct modes of 3D cell migration.

    Science.gov (United States)

    Petrie, Ryan J; Gavara, Núria; Chadwick, Richard S; Yamada, Kenneth M

    2012-04-30

    We search in this paper for context-specific modes of three-dimensional (3D) cell migration using imaging for phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and active Rac1 and Cdc42 in primary fibroblasts migrating within different 3D environments. In 3D collagen, PIP3 and active Rac1 and Cdc42 were targeted to the leading edge, consistent with lamellipodia-based migration. In contrast, elongated cells migrating inside dermal explants and the cell-derived matrix (CDM) formed blunt, cylindrical protrusions, termed lobopodia, and Rac1, Cdc42, and PIP3 signaling was nonpolarized. Reducing RhoA, Rho-associated protein kinase (ROCK), or myosin II activity switched the cells to lamellipodia-based 3D migration. These modes of 3D migration were regulated by matrix physical properties. Specifically, experimentally modifying the elasticity of the CDM or collagen gels established that nonlinear elasticity supported lamellipodia-based migration, whereas linear elasticity switched cells to lobopodia-based migration. Thus, the relative polarization of intracellular signaling identifies two distinct modes of 3D cell migration governed intrinsically by RhoA, ROCK, and myosin II and extrinsically by the elastic behavior of the 3D extracellular matrix.

  7. Optical Kerr Effect Spectroscopy of a Nonpolar Solute in Dicationic versus Monocationic Ionic Liquids

    Science.gov (United States)

    Gurung, Eshan; Xue, Lianjie; Tamas, George; Quitevis, Edward

    2014-03-01

    A comparison of the intermolecular dynamics of small nonpolar solute molecules in monocationic and dicationic ionic liquids (ILs) was performed using optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). The optical Kerr effect (OKE) spectrum of CS2 in 1-methyl-3-propylimidazolium bis(trifluoromethane-sulfonyl)amide [C3mim][NTf2] and 1,6-bis(3-methylimidazolium-1-yl) hexane bis(trifluoromethane-sulfonyl)amide [C6(mim)2][NTf2]2 was investigated as a function of concentration at 295 K. An additivity model with components from the subpicosecond dynamics of IL and CS2 was used to interpret the OKE spectra of the mixtures. The spectrum of CS2 in the two ILs is lower in frequency and narrower than that of neat CS2. The spectrum of CS2 in the dicationic IL is higher in frequency than in the monocationic IL. This result shows that CS2 molecule experiences a stiffer potential in dicationic ILs as compared to monocationic ILs. Higher stiffness in C6(mim)2][NTf2]2 might be due to a more ordered arrangement and lower mobility of the alkyl chains linking the imidazolium rings. This work was supported by NSF Grant CHE-1153077.

  8. Effects of polar and nonpolar groups on the solubility of organic compounds in soil organic matter

    Science.gov (United States)

    Chiou, C.T.; Kile, D.E.

    1994-01-01

    Vapor sorption capacities on a high-organic-content peat, a model for soil organic matter (SOM), were determined at room temperature for the following liquids: n-hexane, 1,4-dioxane, nitroethane, acetone, acetonitrile, 1-propanol, ethanol, and methanol. The linear organic vapor sorption is in keeping with the dominance of vapor partition in peat SOM. These data and similar results of carbon tetrachloride (CT), trichloroethylene (TCE), benzene, ethylene glycol monoethyl ether (EGME), and water on the same peat from earlier studies are used to evaluate the effect of polarity on the vapor partition in SOM. The extrapolated liquid solubility from the vapor isotherm increases sharply from 3-6 wt % for low-polarity liquids (hexane, CT, and benzene) to 62 wt % for polar methanol and correlates positively with the liquid's component solubility parameters for polar interaction (??P) and hydrogen bonding (??h). The same polarity effect may be expected to influence the relative solubilities of a variety of contaminants in SOM and, therefore, the relative deviations between the SOM-water partition coefficients (Kom) and corresponding octanol-water partition coefficients (Kow) for different classes of compounds. The large solubility disparity in SOM between polar and nonpolar solutes suggests that the accurate prediction of Kom from Kow or Sw (solute water solubility) would be limited to compounds of similar polarity.

  9. Improving oil recovery in the CO2 flooding process by utilizing nonpolar chemical modifiers☆

    Institute of Scientific and Technical Information of China (English)

    Yong Yang; Xiangliang Li; Ping Guo; Yayun Zhuo; Yong Sha

    2016-01-01

    By means of experiments of CO2 miscibility with crude oil, four nonpolar chemicals were evaluated in order to enhance the miscibility of CO2 with crude oil. Through pre-slug injection and joint injection of toluene in CO2, crude oil displacement experiments in the slim-tube were conducted to investigate effects of the toluene-enhanced CO2 flooding under simulated subterranean reservoir conditions. Experimental results showed that toluene can enhance extraction of oil into CO2 and dissolution of CO2 into oil with the increment of 251%and 64%respectively. Addition of toluene can obviously improve the oil recovery in either pre-slug injection or joint injection, and the crude oil recovery increased with the increase of the toluene concentration. The oil recov-ery can increase by 22.5%in pre-slug injection with the high toluene concentration. Pre-slug injection was recom-mended because it can consume less toluene than joint injection. This work could be useful to development and application of the CO2 flooding in the oil recovery as wel as CO2 emission reduction.

  10. Roles of urea and TMAO on the interaction between extended non-polar peptides

    Science.gov (United States)

    Su, Zhaoqian; Dias, Cristiano

    Urea and trimethylamine n-oxide (TMAO) are small molecules known to destabilize and stabilize, respectively, the structure of proteins when added to aqueous solution. To unravel the molecular mechanisms of these cosolvents on protein structure we perform explicit all-atom molecular dynamics simulations of extended poly-alanine and polyleucine dimers. We use an umbrella sampling protocol to compute the potential of mean force (PMF) of dimers at different concentrations of urea and TMAO. We find that the large non-polar side chain of leucine is affected by urea whereas backbone atoms and alanine's side chain are not. Urea is found to occupy positions between leucine's side chains that are not accessible to water. This accounts for extra Lennard-Jones bonds between urea and side chains that favors the unfolded state. These bonds compete with urea-solvent interactions that favor the folded state. The sum of these two energetic terms provide the enthalpic driving force for unfolding. We show here that this enthalpy correlate with the potential of mean force of poly-leucine dimers. Moreover, the framework developed here is general and may be used to provide insights into effects of other small molecules on protein interactions. The effect of the TMAO will be in the presentation. Department of Physics, University Heights, Newark, New Jersey, 07102-1982.

  11. Competitive and cooperative adsorption behaviors of phenol and aniline onto nonpolar macroreticular adsorbents

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-ming; CHEN Jin-long; PAN Bing-cai; ZHANG Quan-xing

    2005-01-01

    The adsorption behaviors of phenol and aniline on nonpolar macroreticular adsorbents( NDA100 and Amberlite XAD4) were investigated in single or binary batch system at 293K and 313K respectively in this study. The results indicated that the adsorption isotherms of phenol and aniline on both adsorbents in both systems fitted well Langmuir equation, which indicated a favourable and exothermic process. At the lower equilibrium concentrations, the individual amount adsorbed of phenol or aniline or macroreticular adsorbents in single-component systems was higher than those in binary-component systems because of the competition between phenol and aniline towards the adsorption sites. It is noteworthy, on the contrast, that at higher concentrations, the total uptake amounts of phenol and aniline in binary-component systems were obviously larger than that in single-component systems, and a large excess was noted on the adsorbent surface at saturation, which is presumably due to the cooperative effect primarily arisen from the hydrogen bonding or weak acidbase interaction between phenol and aniline.

  12. A silicone column for GC analysis of polar and nonpolar chemicals

    Science.gov (United States)

    Shen, T. C.

    1991-10-01

    The investigation of the Saturnian System is being proposed jointly by NASA and the European Space Agency (ESA). The mission is scheduled for a launch in 1996. The mission provides an opportunity for close observation and exploration of Saturn's atmosphere, the complex Saturnian System of satellites and rings, Titan (Saturn's planet-sized moon), and Saturn's magnetosphere. The mission gives special attention to Titan which is blanketed by a thick, opaque atmosphere. An atmospheric probe will be deposited into the Titan Atmosphere for in situ measurement during a slow, three hour descent to the surface. The results from this analysis may provide the information which is important to the research of chemical evolution, and the origin of life. An analytical system was developed as a part of the Titan Aerosol Gas Experiment (TAGEX), a proposed experiment for the Cassini Mission. This system will use two highly sensitive detectors, the Metastable Ionization Detector (MID) and the Ion Mobility Spectrometer (IMS). Unfortunately, when commercial columns are utilized with these highly sensitive detectors, volatile components continuously bleed from the column and interfere with the detector. In addition, light columns must be able to separate polar and nonpolar organic chemicals within 10-15 minutes under isothermal conditions for the Titan Mission. Therefore, a highly crosslinked silicone polymeric packed column was developed which is able to efficiently separate amines, alcohols, and hydrocarbons with retention times less that 15 minutes at 100 C isothermal condition.

  13. Self-consistent theory of nanodomain formation on nonpolar surfaces of ferroelectrics

    Science.gov (United States)

    Morozovska, Anna N.; Ievlev, Anton V.; Obukhovskii, Vyacheslav V.; Fomichov, Yevhen; Varenyk, Oleksandr V.; Shur, Vladimir Ya.; Kalinin, Sergei V.; Eliseev, Eugene A.

    2016-04-01

    We propose a self-consistent theoretical approach capable of describing the features of the anisotropic nanodomain formation induced by a strongly inhomogeneous electric field of a charged scanning probe microscopy tip on nonpolar cuts of ferroelectrics. We obtained that a threshold field, previously regarded as an isotropic parameter, is an anisotropic function that is specified from the polar properties and lattice pinning anisotropy of a given ferroelectric in a self-consistent way. The proposed method for the calculation of the anisotropic threshold field is not material specific, thus the field should be anisotropic in all ferroelectrics with the spontaneous polarization anisotropy along the main crystallographic directions. The most evident examples are uniaxial ferroelectrics, layered ferroelectric perovskites, and low-symmetry incommensurate ferroelectrics. Obtained results quantitatively describe the differences at several times in the nanodomain length experimentally observed on X and Y cuts of LiNb O3 and can give insight into the anisotropic dynamics of nanoscale polarization reversal in strongly inhomogeneous electric fields.

  14. Adsorption of polar, nonpolar, and substituted aromatics to colloidal graphene oxide nanoparticles.

    Science.gov (United States)

    Wang, Fang; Haftka, Joris J-H; Sinnige, Theo L; Hermens, Joop L M; Chen, Wei

    2014-03-01

    We conducted batch adsorption experiments to understand the adsorptive properties of colloidal graphene oxide nanoparticles (GONPs) for a range of environmentally relevant aromatics and substituted aromatics, including model nonpolar compounds (pyrene, phenanthrene, naphthalene, and 1,3-dichlorobenzene) and model polar compounds (1-naphthol, 1-naphthylamine, 2,4-dichlorophenol, and 2,4-dinitrotoluene). GONPs exhibited strong adsorption affinities for all the test compounds, with distribution coefficients on the order of 10(3)-10(6) L/kg. Adsorption to GONPs is much more linear than to carbon nanotubes (CNTs) and C60, likely because GO nanoflakes are essentially individually dispersed (rendering adsorption sites of similar adsorption energy) whereas CNT/C60 are prone to bundling/aggregation. For a given compound GONPs and CNTs often exhibit different adsorption affinities, which is attributable to the differences in both the morphology and surface chemistry between the two nanomaterials. Particularly, the high surface O-content of GONPs enables strong H-bonding and Lewis acid-base interactions with hydroxyl- and amino-substituted aromatics.

  15. Molecular Dynamics Simulation of Behaviours of Non-Polar Droplets Merging and Interactions with Hydrophobic Surfaces

    Institute of Scientific and Technical Information of China (English)

    Y.Y.Yan; C.Y.Ji

    2008-01-01

    This paper presents a molecular dynamics simulation of the behaviours of non-polar droplets merging and also the fluid molecules interacting with a hydrophobic surface. Such behaviours and transport phenomena are popular in general micro-channel flow boiling and two-phase flow. The droplets are assumed to be composed of Lennards-Jones type molecules. Periodic boundary conditions are applied in three coordinate directions ofa 3-D system, where there exist two liquid droplets and their vapour. The two droplets merge when they come within the prescribed small distance. The merging of two droplets apart from each other at different initial distances is tested and the possible larger (or critical) non-dimensional distance, in which droplets merging can occur, is discussed. The evolution of the merging process is simulated numerically by employing the Molecular Dynamics (MD) method. For interactions with hydrophobic solid wail, a system with fluid confined between two walls is used to study the wetting phenomena of fluid and solid wail. The results are compared with those of hydrophilic wall to show the unique characteristics of hydrophobic interactions by microscopic methods.

  16. Composition of the non-polar extracts and antimicrobial activity of Chorisia insignis HBK. leaves

    Directory of Open Access Journals (Sweden)

    Salma Ahmed Mahmoud El Sawi

    2014-12-01

    Full Text Available Objective: To investigate the chemical constituents of the petroleum ether extract and the ether fraction of the 70% ethanol extract of Chorisia insignis HBK. leaves, as well as screen its antimicrobial activity. Methods: Different chromatographic methods were applied to investigate the non-polar extracts and the diffusion assay method was applied to study the antimicrobial activity. Results: A total of 50 compounds from the unsaponifiable matter and 20 fatty acid methyl esters were identified from the petroleum ether extract by GC/MS analysis. n-Hentriacontane, n-tritriacontane, stigmastanol, 3-methoxy-5, 6-dihydrostigmasterol, 7,8-dihydroergosterol, 4-methylcholesterol, cholestanol, multiflorenol, cholest-5-en-3-one, cholest-6-one, 5,6- dihydroergosterol, stigmasterol, dihydroalbigenin and 11-methyl-Δ5,7,9,15,17,23-triacont-hex-ene were isolated from the petroleum ether extract. Methyl heptacosanoate and quinic acid ester of rhamnose were isolated from the ether fraction of the 70% ethanol extract. Antimicrobial activity of the total alcohol extract and the successive fractions showed that the ether and the ethyl acetate fractions have potent antibacterial activity against Bacillus subtilis and Bacillus cereus. Conclusions: The ether and the ethyl acetate fractions could be used in pharmaceutical formulations as antibacterial agents against Bacillus subtilis and Bacillus cereus, and further clinical trials should be performed in order to support the above investigations.

  17. Piezoelectricity and rotostriction through polar and non-polar coupled instabilities in bismuth-based piezoceramics

    Science.gov (United States)

    Acosta, Matias; Schmitt, Ljubomira A.; Cazorla, Claudio; Studer, Andrew; Zintler, Alexander; Glaum, Julia; Kleebe, Hans-Joachim; Donner, Wolfgang; Hoffman, Mark; Rödel, Jürgen; Hinterstein, Manuel

    2016-07-01

    Coupling of order parameters provides a means to tune functionality in advanced materials including multiferroics, superconductors, and ionic conductors. We demonstrate that the response of a frustrated ferroelectric state leads to coupling between order parameters under electric field depending on grain orientation. The strain of grains oriented along a specific crystallographic direction, , is caused by converse piezoelectricity originating from a ferrodistortive tetragonal phase. For hhh> oriented grains, the strain results from converse piezoelectricity and rotostriction, as indicated by an antiferrodistortive instability that promotes octahedral tilting in a rhombohedral phase. Both strain mechanisms combined lead to a colossal local strain of (2.4 ± 0.1) % and indicate coupling between oxygen octahedral tilting and polarization, here termed “rotopolarization”. These findings were confirmed with electromechanical experiments, in situ neutron diffraction, and in situ transmission electron microscopy in 0.75Bi1/2Na1/2TiO3-0.25SrTiO3. This work demonstrates that polar and non-polar instabilities can cooperate to provide colossal functional responses.

  18. Electroluminescence from nonpolar n-ZnO/p-AlGaN heterojunction light-emitting diode on r-sapphire

    Science.gov (United States)

    Chen, Jingwen; Zhang, Jun; Dai, Jiangnan; Wu, Feng; Wang, Shuai; Chen, Cheng; Long, Hanling; Liang, Renli; Zhao, Chong; Chen, Changqing; Tang, Zhiwu; Cheng, Hailing; He, Yunbin; Li, Mingkai

    2017-03-01

    Nonpolar a-plane n-ZnO/p-AlGaN heterojunction light-emitting diodes (LEDs) have been prepared on r-sapphire substrate using metal organic chemical vapor deposition and a pulsed laser deposition method. The dominant electroluminescence emission at 390 nm from the interband transition in n-ZnO layer under a forward bias was observed. Interestingly, electroluminescence with emission at 385 nm based on an avalanche mechanism was also achieved under reverse bias. The mechanisms of both the electroluminescence and I–V characteristics are discussed in detail by considering the avalanche effect. It is demonstrated that the crystalline quality of n-ZnO, not the p-AlGaN, is what affects the performance of the nonpolar ZnO based avalanche LED.

  19. Homoepitaxial nonpolar (10-10) ZnO/ZnMgO monolithic microcavities: Towards reduced photonic disorder

    Energy Technology Data Exchange (ETDEWEB)

    Zuniga-Perez, J., E-mail: jzp@crhea.cnrs.fr; Kappei, L.; Deparis, C.; Chenot, S.; Leroux, M. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Reveret, F.; Jamadi, O.; Leymarie, J. [Clermont Université, Institut Pascal (IP), BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6602, IP, F-63171 Aubière (France); Grundmann, M. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Institut für Experimentelle Physik II, Fakultät für Physik und Geowissenschaften, Universität Leipzig, Linnestr. 5, 04103 Leipzig (Germany); Prado, E. de [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, c/Dr Moliner 50, Burjassot, Valencia 46100 (Spain)

    2016-06-20

    Nonpolar ZnO/ZnMgO-based optical microcavities have been grown on (10-10) m-plane ZnO substrates by plasma-assisted molecular beam epitaxy. Reflectivity measurements indicate an exponential increase of the cavity quality factor with the number of layers in the distributed Bragg reflectors. Most importantly, microreflectivity spectra recorded with a spot size in the order of 2 μm show a negligible photonic disorder (well below 1 meV), leading to local quality factors equivalent to those obtained by macroreflectivity. The anisotropic character of the nonpolar heterostructures manifests itself both in the surface features, elongated parallel to the in-plane c direction, and in the optical spectra, with two cavity modes being observed at different energies for orthogonal polarizations.

  20. An analytical method of predicting Lee-Kesler-Ploecker binary interaction coefficients: Part 1, For non-polar hydrocarbon mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sand, J.R.

    1994-12-31

    An analytical method is proposed for finding numerical values of binary interaction coefficients for non-polar hydrocarbon mixtures when the Lee-Kesler (LK) equation of state is applied. The method is based on solving simultaneous equations, which are Ploecker`s mixing rules for pseudocritical parameters of a mixture, and the Lee-Kesler equation for the saturation line. For a hydrocarbon mixture, the method allows prediction of {kappa}{sub ij} interaction coefficients (ICs) which are close to values obtained by processing experimental p-v-t data on the saturation line and subsequent averaging. For mixtures of hydrocarbon molecules containing from 2 to 9 carbon atoms, the divergence between calculated and experimentally based ICs is no more than {plus_minus}0.4%. The possibility of extending application of this method to other non-polar substances is discussed.

  1. Association of the novel aminoglycoside resistance determinant RmtF with NDM carbapenemase in Enterobacteriaceae isolated in India and the UK

    DEFF Research Database (Denmark)

    Hidalgo, Laura; Hopkins, Katie L; Gutierrez, Belen;

    2013-01-01

    16S rRNA methyltransferases are an emerging mechanism conferring high-level resistance to clinically relevant aminoglycosides and have been associated with important mechanisms such as NDM-1. We sought genes encoding these enzymes in isolates highly resistant (MIC >200 mg/L) to gentamicin and ami...

  2. Characterization of Antimicrobial Resistance of Listeria monocytogenes Strains Isolated from a Pork Processing Plant and Its Respective Meat Markets in Southern China

    DEFF Research Database (Denmark)

    Li, Lili; Olsen, Rikke Heidemann; Ye, Lei;

    2016-01-01

    ) being predominant (42.3%, 33/78). Antimicrobial resistance was most frequently observed for tetracycline (20.5%, 16/78), streptomycin (9.0%, 7/78), cefotaxime (7.7%, 6/78), and gentamicin (6.4%, 5/78). Multiple resistances occurred among 10.2% (8/78) isolates. All strains were sensitive to ampicillin...

  3. The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem.

    Science.gov (United States)

    Humphreys, C J; Griffiths, J T; Tang, F; Oehler, F; Findlay, S D; Zheng, C; Etheridge, J; Martin, T L; Bagot, P A J; Moody, M P; Sutherland, D; Dawson, P; Schulz, S; Zhang, S; Fu, W Y; Zhu, T; Kappers, M J; Oliver, R A

    2017-02-03

    We have used high resolution transmission electron microscopy (HRTEM), aberration-corrected quantitative scanning transmission electron microscopy (Q-STEM), atom probe tomography (APT) and X-ray diffraction (XRD) to study the atomic structure of (0001) polar and (11-20) non-polar InGaN quantum wells (QWs). This paper provides an overview of the results. Polar (0001) InGaN in QWs is a random alloy, with In replacing Ga randomly. The InGaN QWs have atomic height interface steps, resulting in QW width fluctuations. The electrons are localised at the top QW interface by the built-in electric field and the well-width fluctuations, with a localisation energy of typically 20meV. The holes are localised near the bottom QW interface, by indium fluctuations in the random alloy, with a localisation energy of typically 60meV. On the other hand, the non-polar (11-20) InGaN QWs contain nanometre-scale indium-rich clusters which we suggest localise the carriers and produce longer wavelength (lower energy) emission than from random alloy non-polar InGaN QWs of the same average composition. The reason for the indium-rich clusters in non-polar (11-20) InGaN QWs is not yet clear, but may be connected to the lower QW growth temperature for the (11-20) InGaN QWs compared to the (0001) polar InGaN QWs.

  4. Intratympanic gentamicin therapy for control of vertigo in unilateral Meniere's disease : a prospective, double-blind, randomized, placebo-controlled trial

    NARCIS (Netherlands)

    Postema, Rolf J.; Kingma, Charlotte M.; Wit, Hero P.; Albers, Frans W. J.; Van Der Laan, Bernard F. A. M.

    2008-01-01

    Conclusions. Intratympanic application of gentamicin is a relatively safe and efficient treatment for the reduction of complaints of vertigo attacks associated with Meniere's disease. The treatment also reduces the severity of the perceived aural fullness. Objective. To investigate the effectiveness

  5. Protective Effect of Hexane and Ethanol Extract of Piper Longum L. on Gentamicin-Induced Hair Cell Loss in Neonatal Cultures

    National Research Council Canada - National Science Library

    Yadav, Mukesh Kumar; Choi, June; Song, Jae-Jun

    2014-01-01

    Gentamicin (GM) is a commonly used aminoglycoside antibiotic that generates free oxygen radicals within the inner ear, which can cause vestibulo-cochlear toxicity and permanent damage to the sensory hair cells and neurons. L. (PL...

  6. Predicting Partitioning and Diffusion Properties of Nonpolar Chemicals in Biotic Media and Passive Sampler Phases by GC × GC.

    Science.gov (United States)

    Nabi, Deedar; Arey, J Samuel

    2017-02-14

    The chemical parameters needed to explain and predict bioavailability, biodynamics, and baseline toxicity are not readily available for most nonpolar chemicals detected in the environment. Here, we demonstrate that comprehensive two-dimensional gas chromatography (GC × GC) retention times can be used to predict 26 relevant properties for nonpolar chemicals, specifically: partition coefficients for diverse biotic media and passive sampler phases; aquatic baseline toxicity; and relevant diffusion coefficients. The considered biotic and passive sampler phases include membrane and storage lipids, serum and muscle proteins, carbohydrates, algae, mussels, polydimethylsiloxane, polyethylene, polyoxymethylene, polyacrylate, polyurethane, and semipermeable membrane devices. GC × GC-based chemical property predictions are validated with a compilation of 1038 experimental property data collected from the literature. As an example application, we overlay a map of baseline toxicity to fathead minnows onto the separated analyte signal of a polychlorinated alkanes (chlorinated paraffins) technical mixture that contains 7820 congeners. In a second application, GC × GC-estimated properties are used to parametrize multiphase partitioning models for mammalian tissues and organs. In a third example, we estimate chemical depuration kinetics for mussels. Finally, we illustrate an approach to screen the GC × GC chromatogram for nonpolar chemicals of potentially high concern, defined based on their GC × GC-estimated biopartitioning properties, diffusion properties, and baseline toxicity.

  7. Tailoring of polar and nonpolar ZnO planes on MgO (001) substrates through molecular beam epitaxy.

    Science.gov (United States)

    Zhou, Hua; Wang, Hui-Qiong; Liao, Xia-Xia; Zhang, Yufeng; Zheng, Jin-Cheng; Wang, Jia-Ou; Muhemmed, Emin; Qian, Hai-Jie; Ibrahim, Kurash; Chen, Xiaohang; Zhan, Huahan; Kang, Junyong

    2012-03-09

    Polar and nonpolar ZnO thin films were deposited on MgO (001) substrates under different deposition parameters using oxygen plasma-assisted molecular beam epitaxy (MBE). The orientations of ZnO thin films were investigated by in situ reflection high-energy electron diffraction and ex situ X-ray diffraction (XRD). The film roughness measured by atomic force microscopy evolved as a function of substrate temperature and was correlated with the grain sizes determined by XRD. Synchrotron-based X-ray absorption spectroscopy (XAS) was performed to study the conduction band structures of the ZnO films. The fine structures of the XAS spectra, which were consistent with the results of density functional theory calculation, indicated that the polar and nonpolar ZnO films had different electronic structures. Our work suggests that it is possible to vary ZnO film structures from polar to nonpolar using the MBE growth technique and hence tailoring the electronic structures of the ZnO films.PACS: 81; 81.05.Dz; 81.15.Hi.

  8. The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

    Science.gov (United States)

    Dawson, P.; Schulz, S.; Oliver, R. A.; Kappers, M. J.; Humphreys, C. J.

    2016-05-01

    In this paper, we compare and contrast the experimental data and the theoretical predictions of the low temperature optical properties of polar and nonpolar InGaN/GaN quantum well structures. In both types of structure, the optical properties at low temperatures are governed by the effects of carrier localisation. In polar structures, the effect of the in-built electric field leads to electrons being mainly localised at well width fluctuations, whereas holes are localised at regions within the quantum wells, where the random In distribution leads to local minima in potential energy. This leads to a system of independently localised electrons and holes. In nonpolar quantum wells, the nature of the hole localisation is essentially the same as the polar case but the electrons are now coulombically bound to the holes forming localised excitons. These localisation mechanisms are compatible with the large photoluminescence linewidths of the polar and nonpolar quantum wells as well as the different time scales and form of the radiative recombination decay curves.

  9. Interactions of methanol, ethanol, and 1-propanol with polar and nonpolar species in water at cryogenic temperatures.

    Science.gov (United States)

    Souda, Ryutaro

    2017-01-18

    Methanol is known as a strong inhibitor of hydrate formation, but clathrate hydrates of ethanol and 1-propanol can be formed in the presence of help gases. To elucidate the hydrophilic and hydrophobic effects of alcohols, their interactions with simple solute species are investigated in glassy, liquid, and crystalline water using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. Nonpolar solute species embedded underneath amorphous solid water films are released during crystallization, but they tend to withstand water crystallization under the coexistence of methanol additives. The CO2 additives are released after crystallization along with methanol desorption. These results suggest strongly that nonpolar species that are hydrated (i.e., caged) associatively with methanol can withstand water crystallization. In contrast, ethanol and 1-propanol additives weakly affect the dehydration of nonpolar species during water crystallization, suggesting that the former tend to be caged separately from the latter. The hydrophilic vs. hydrophobic behavior of alcohols, which differs according to the aliphatic group length, also manifests itself in the different abilities of surface segregation of alcohols and their effects on the water crystallization kinetics.

  10. Evaluation of gentamicin and lidocaine release profile from gum acacia-crosslinked-poly(2-hydroxyethylmethacrylate)-carbopol based hydrogels.

    Science.gov (United States)

    Singh, Baljit; Dhiman, Abhishek

    2017-01-27

    In this manuscript an attempt has been made to incorporate both, antibiotic agent 'gentamicin' and pain relieving agent 'lidocaine' into the gum acacia-poly(2-hydroxyethylmethacrylate)-carbopol based hydrogel for wound dressing application. Drug release, gel strength, network parameter, antimicrobial activity and biodegradation properties of hydrogel have been evaluated. Porous microstructure of the hydrogel was observed in cryo-SEM images. The hydrogel showed mesh size 37.29 nm, cross-link density 2.19× 10-5 mol/cm3, molecular weight between two cross-links 60.25× 10-3 g/mol and gel strength 0.625±0.112 N in simulated wound fluid. The hydrogels were evaluated as a drug carrier for model drugs gentamicin and lidocaine. The release of these drugs occurred through Fickian diffusion mechanism and release profile of the drugs was best fitted in first order kinetic model.

  11. Nephro-protective effect of vitamin C and Nigella sativa oil on gentamicin associated nephrotoxicity in rabbits.

    Science.gov (United States)

    Saleem, Uzma; Ahmad, Bashir; Rehman, Kanwal; Mahmood, Saeed; Alam, Maqsood; Erum, Alia

    2012-10-01

    Oxidative stress causes the generation of reactive oxygen species (ROS) that lead to nephrotoxicity. An aminoglycoside, gentamicin, has pronounced nephrotoxic effect in humans and animals and this study was planned to observe the nephro-protective effect of antioxidants, vitamin C and Nigella sativa oil. Serum creatinine, blood urea nitrogen, and antioxidant activity were measured as indicators of nephrotoxicity for all the groups of rabbits. Results showed that vitamin C and Nigella sativa oil both had nephro-protective effect as they lowered the values of nephrotoxicity indicators (serum creatinine, blood urea nitrogen, and antioxidant activity) as compared to gentamicin control group values. When these two antioxidants were given as combination, they proved to have synergistic nephro-protective effect.

  12. RELEASE OF GENTAMICIN FROM CEMENT SPACERS IN TWO-STAGE PROCEDURES FOR HIP AND KNEE PROSTHETIC INFECTION: AN IN VIVO PHARMACOKINETIC STUDY WITH CLINICAL FOLLOW-UP.

    Science.gov (United States)

    Balato, G; Ascione, T; Rosa, D; Pagliano, P; Solarino, G; Moretti, B; Mariconda, M

    2015-01-01

    Eighteen patients undergoing two-stage exchange arthroplasty for infected total hip or knee arthroplasty using gentamicin-loaded bone cement spacers (80g bone cement, 2 g gentamicin and 2 g clindamycin) were studied. The concentration of gentamicin eluted from the spacers was assessed on samples of blood, urine, and drainage fluid that were collected from each patient at set intervals during the 48 hours following the first-stage surgery. The hip and knee cement spacers showed similar curve of release over the first postoperative hours (early peak followed by slow release), but the mean gentamicin concentration in the drainage fluid was higher in patients with hip spacers compared to patients with knee spacers (30.61±19.47 mg/L vs 17.43±13,63 mg/L, p less than 0.05). In patients with hip spacers, the mean, maximum, and minimum concentration of gentamicin was higher with respect to the minimum inhibitory concentration (MIC) break point for Staphylococcus spp, Pseudomonas Aeruginosa and Enterobacteriaceae throughout the first postoperative 48 h. Conversely, in 25% of patients with a knee spacer a drug concentration below the MIC break point for Gram negative bacteria was found in the drainage fluid after 12 h. Gentamicin levels in the blood samples were negligible over the entire time interval and were steadily well below the renal toxicity reference. The highest urinary concentration of gentamicin was observed between 4 and 9 h postoperatively. Subsequently, it gradually declined until 48 h. Clinically, the rate of cure was 100% at a mean follow-up of 113 weeks (range 90-182). Gentamicin-loaded cement spacers offer the advantage of achieving early high concentrations of the antibiotic directly at the site of infection but especially in the knee a systemic antibiotic therapy must be given as a complement to the spacer implantation to eradicate periprosthetic joint infection (PJI).

  13. Light-microscopic immunocytochemistry for Gentamicin and its use for studying uptake of the drug in kidney

    DEFF Research Database (Denmark)

    Fujiwara, Kunio; Shin, Masashi; Matsunaga, Hayato

    2009-01-01

    Gentamicin (GM) is a widely used antibiotic but shows renal toxicity. We produced a serum against GM (anti-GM) conjugated to bovine serum albumin with N-(gamma-maleimidobutyryloxy)succinimide. The antiserum was monospecific for GM and did not cross-react with the analog streptomycin, tobramycin...... compartments. This approach should be useful for accurately detecting the uptake and toxicity of the antibiotic in different tissues....

  14. Kinetics of kill of bacterial conjunctivitis isolates with moxifloxacin, a fluoroquinolone, compared with the aminoglycosides tobramycin and gentamicin

    Directory of Open Access Journals (Sweden)

    Rudolph S Wagner

    2010-01-01

    Full Text Available Rudolph S Wagner1, David B Granet2, Steven J Lichtenstein3, Tiffany Jamison4, Joseph J Dajcs4, Robert D Gross5, Paul Cockrum41New Jersey Medical School, Newark, NJ, USA; 2Ratner Children’s Eye Center, University of California – San Diego, La Jolla, CA, USA; 3University of Illinois College of Medicine at Peoria, Peoria, Illinois, USA; 4Alcon Research, Ltd, Fort Worth, TX, USA; 5Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX, USAPurpose: To compare the kinetics and speed of kill of Streptococcus pneumoniae and Haemophilus influenzae on exposure to three topical ophthalmic antibiotic solutions.Materials and methods: Bacterial conjunctivitis isolates of S. pneumoniae and H. influenzae were exposed to 1:1000 dilutions of moxifloxacin 0.5%, tobramycin 0.3%, gentamicin 0.3%, and water (control. At 15, 30, 60, 120, and 180 minutes after exposure, aliquots were collected, cells were cultured, and viable cell counts were determined using standard microbiological methods.Results: Moxifloxacin achieved 99.9% kill (3-log reduction at approximately 2 hours for S. pneumoniae and at 15 minutes for H. influenzae. Tobramycin and gentamicin did not achieve 3-log reduction of S. pneumoniae during the 180-minute study period. An increase in bacterial growth was noted for these isolates. Gentamicin took more than 120 minutes to achieve the 3-log reduction of H. influenzae and tobramycin did not reach the 3-log reduction of this pathogen during the 180-minute study period.Conclusion: Moxifloxacin killed S. pneumoniae and H. influenzae in vitro faster than tobramycin and gentamicin, suggesting its potential clinical benefit as a first-line treatment for bacterial conjunctivitis to minimize patient symptoms and to limit the contagiousness of the disease.Keywords: kinetics of kill, bacterial conjunctivitis, in vitro, Streptococcus pneumoniae, Haemophilus influenzae, fluoroquinolones, aminoglycosides

  15. Evaluation of biochemical effects of Casuarina equisetifolia extract on gentamicin-induced nephrotoxicity and oxidative stress in rats. Phytochemical analysis

    OpenAIRE

    El-Tantawy, Walid Hamdy; Mohamed, Shaza Abdel-Halim; Abd Al Haleem, Ekram Nemr

    2013-01-01

    Nephrotoxicity is defined as renal dysfunction that arises as result of exposure to external agents such as drugs and environmental chemicals. The present work was undertaken to carry out the phytochemical study and nephroprotective activity of methanolic extract of Casuarina equisetifolia leaves in gentamicin-induced nephrotoxicity in Wistar rats. Flavonoids and phenolic acids were identified and quantified using high performance liquid chromatography. Subcutaneous injection of rats with gen...

  16. Contaminated fistula following J-pouch ileoanal reservoir. Treatment with a collagen sponge containing gentamicin and metronidazole. Case report

    DEFF Research Database (Denmark)

    Nielsen, R; Bülow, Steffen; Moesgaard, F

    1991-01-01

    In a 55-year-old woman, a 1 x 5 cm fistula developed in the ileoanal anastomosis after restorative proctocolectomy with J-pouch ileoanal reservoir and temporary ileostomy for intractable ulcerative colitis. The fistula extended between the pouch and the sacral bone. Lasting closure was achieved b...... by intrafistular placement of a collagen sponge containing gentamicin and soaked in metronidazole solution and pouch drainage through a transanal Foley catheter....

  17. Contaminated fistula following J-pouch ileoanal reservoir. Treatment with a collagen sponge containing gentamicin and metronidazole. Case report

    DEFF Research Database (Denmark)

    Nielsen, R; Bülow, Steffen; Moesgaard, F

    1991-01-01

    In a 55-year-old woman, a 1 x 5 cm fistula developed in the ileoanal anastomosis after restorative proctocolectomy with J-pouch ileoanal reservoir and temporary ileostomy for intractable ulcerative colitis. The fistula extended between the pouch and the sacral bone. Lasting closure was achieved b...... by intrafistular placement of a collagen sponge containing gentamicin and soaked in metronidazole solution and pouch drainage through a transanal Foley catheter....

  18. Influence of osmotic and oncotic factors on gentamicin and insulin transport across the peritoneal membrane in vitro.

    Science.gov (United States)

    Grzelak, Teresa; Wojciechowska, Katarzyna; Szary, Beata; Czyzewska, Krystyna

    2011-01-01

    Glucose or its polymer is usually added to dialysis solution for the development of sufficient ultrafiltration during peritoneal dialysis. The aim of the present study was to determine the influence of glucose and icodextrin on the transport of gentamicin and insulin from the mesothelial to the interstitial side of the peritoneal membrane. Transfer values are expressed as a coefficient of diffusive permeability, P, in centimeters per second. Each of the molecules was tested in 3 series of experiments using rabbit parietal peritoneum, a modified Ussing chamber, and a mathematical model of mass transport. First, transperitoneal transfers of gentamicin (0.040 g/dL) and insulin (0.1 g/dL) were analyzed in control conditions for 120 minutes. Then, transport parameters for gentamicin and insulin were separately determined before (15-60 minutes) and after (75-120 minutes or 75-130 minutes) the application of glucose (1.8 g/dL) or icodextrin (2 g/ dL) on the mesothelial side of the peritoneal membrane. Insulin transport was observed to be stable in the control series. Gentamicin transfer was not stable; its passage declined by 52% (p insulin, the mean P (+ standard error of the mean) was 0.15 +/- 0.02 cm/s (x0.0001) at the first hour of transfer and 0.14 - 0.02 cm/s (x0.0001) at the second. Glucose induced a nonsignificant intensification of insulin transport. Icodextrin increased insulin passage by 107% (p insulin transport from the mesothelial to the interstitial side of the peritoneum. Similar modifications might be observed in vivo during peritoneal dialysis or continuous intraperitoneal administration of insulin, influencing the efficiency of those treatments.

  19. Electrochemical oxidation of drug residues in water by the example of tetracycline, gentamicin and Aspirin {sup trademark}

    Energy Technology Data Exchange (ETDEWEB)

    Weichgrebe, D.; Danilova, E.; Rosenwinkel, K.H. [Inst. of Water Quality and Waste Management, Univ. of Hannover, Hannover (Germany); Vedenjapin, A.; Baturova, M. [Inst. of Organic Chemistry, Russian Academy of Science, Moscow (Russian Federation)

    2003-07-01

    The electrochemical oxidation as a method to destroy drug residues like Aspirin {sup trademark}, tetracycline or gentamicin in water was investigated with C-Anode (modified by manganese oxides) and Pt Anode. The mechanism of Aspirin {sup trademark} and tetracycline oxidation and the influence of the biocide effect was observed using GC-MS and three different microbiological tests. In general the biological availability increases with progressive oxidation of the antibiotics. (orig.)

  20. Comparative Study of the Characteristics of the Basal Plane Stacking Faults of Nonpolar a-Plane and Semipolar (11(2)2) GaN

    Institute of Scientific and Technical Information of China (English)

    XU Sheng-Rui; HAO Yue; LIN Zhi-Yu; XUE Xiao-Yong; LIU Zi-Yang; MA Jun-Cai; JIANG Teng; MAO Wei; WANG Dang-Hui; ZHANG Jin-Cheng

    2012-01-01

    Nonpolar (11-20) and semipolar (11222) GaN are grown on r-plane and m-plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs). Transmission electron microscopy reveals that the density of BSFs for the semipolar (11-22) and nonpolar a-plane GaN template is 3×105cm-1 and 8×10 cm'1, respectively. The semipolar (11-22) GaN shows an arrowhead-like structure, and the nonpolar a-plane GaN has a much smoother morphology with a streak along the c-axis. Both nonpolar (11-20) and semipolar (11-22) GaN have very strong BSF luminescence due to the optically active character of the BSFs.%Nonpolar (11(2)0) and semipolar (11(2)2) GaN are grown on r-plane and m-plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs).Transmission electron microscopy reveals that the density of BSFs for the semipolar (11(2)2) and nonpolar a-plane GaN template is 3x105 cm-1 and 8×105 cm-1,respectively.The semipolar (11(2)2) GaN shows an arrowhead-like structure,and the nonpolar a-plane GaN has a much smoother morphology with a streak along the c-axis.Both nonpolar (11(2)0) and semipolar (11(2)2) GaN have very strong BSF luminescence due to the optically active character of the BSFs.

  1. NaHS Protects Cochlear Hair Cells from Gentamicin-Induced Ototoxicity by Inhibiting the Mitochondrial Apoptosis Pathway.

    Directory of Open Access Journals (Sweden)

    Yaodong Dong

    Full Text Available Aminoglycoside antibiotics such as gentamicin could cause ototoxicity in mammalians, by inducing oxidative stress and apoptosis in sensory hair cells of the cochlea. Sodium hydrosulfide (NaHS is reported to alleviate oxidative stress and apoptosis, but its role in protecting aminoglycoside-induced hearing loss is unclear. In this study, we investigated the anti-oxidant and anti-apoptosis effect of NaHS in in vitro cultured House Ear Institute-Organ of Corti 1 (HEI-OC1 cells and isolated mouse cochlea. Results from cultured HEI-OC1 cells and cochlea consistently indicated that NaHS exhibited protective effects from gentamicin-induced ototoxicity, evident by maintained cell viability, hair cell number and cochlear morphology, reduced reactive oxygen species production and mitochondrial depolarization, as well as apoptosis activation of the intrinsic pathway. Moreover, in the isolated cochlear culture, NaHS was also demonstrated to protect the explant from gentamicin-induced mechanotransduction loss. Our study using multiple in vitro models revealed for the first time, the potential of NaHS as a therapeutic agent in protecting against aminoglycoside-induced hearing loss.

  2. NaHS Protects Cochlear Hair Cells from Gentamicin-Induced Ototoxicity by Inhibiting the Mitochondrial Apoptosis Pathway

    Science.gov (United States)

    Dong, Yaodong; Liu, Dongliang; Hu, Yue; Ma, Xiulan

    2015-01-01

    Aminoglycoside antibiotics such as gentamicin could cause ototoxicity in mammalians, by inducing oxidative stress and apoptosis in sensory hair cells of the cochlea. Sodium hydrosulfide (NaHS) is reported to alleviate oxidative stress and apoptosis, but its role in protecting aminoglycoside-induced hearing loss is unclear. In this study, we investigated the anti-oxidant and anti-apoptosis effect of NaHS in in vitro cultured House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and isolated mouse cochlea. Results from cultured HEI-OC1 cells and cochlea consistently indicated that NaHS exhibited protective effects from gentamicin-induced ototoxicity, evident by maintained cell viability, hair cell number and cochlear morphology, reduced reactive oxygen species production and mitochondrial depolarization, as well as apoptosis activation of the intrinsic pathway. Moreover, in the isolated cochlear culture, NaHS was also demonstrated to protect the explant from gentamicin-induced mechanotransduction loss. Our study using multiple in vitro models revealed for the first time, the potential of NaHS as a therapeutic agent in protecting against aminoglycoside-induced hearing loss. PMID:26295804

  3. Protective Effect of Carvacrol on Renal Functional and Histopathological Changes in Gentamicin-Induced-Nephrotoxicity in Rats

    Directory of Open Access Journals (Sweden)

    Hassan Ahmadvand

    2016-04-01

    Full Text Available Background Nephrotoxicity is one of the most important side effects of the use of gentamicin sulphate (GS resulted in reactive oxygen species generation. Antioxidant compounds played effective roles in reduction of renal injuries caused by using of gentamicin. Carvacrol is a strong antioxidant compound. Objectives The aim of this study is to explore the effect of carvacrol inhibition in lesions of gentamicin-induced nephrotoxicity. Materials and Methods In this experimental study, 32 male mature Sprague-Dawley rats were divided into 4 groups of 8; group1: control, group 2 sham received daily carvacrol injection (74 mg/kg for 12 days, group 3 received daily GS injection (100 mg/kg for 12 days, group 4 received daily GS (100 mg/kg and carvacrol (74 mg/kg for 12 days. After 12 days, rats were anaesthetized, blood sample were obtained and kidneys were removed then stained with hematoxylin and eosin method and then were studied histophatologically. Serum creatinine and urea were measured. Results Flow treatment of nephrotoxic animals with carvacrol could significantly inhibit leukocyte infiltration (9.42% and tubular necrosis (38.18% in comparison with the nephrotoxic untreated group. Carvacrol significantly decreased the levels of urea and creatinine in treated group compared with the nephrotoxic untreated group. Conclusions The findings showed that carvacrol alleviates loss of leukocyte infiltration (9.42% and tubular necrosis and exerts beneficial effects on kidney function test in nephrotoxic group.

  4. Evaluation of biochemical effects of Casuarina equisetifolia extract on gentamicin-induced nephrotoxicity and oxidative stress in rats. Phytochemical analysis.

    Science.gov (United States)

    El-Tantawy, Walid Hamdy; Mohamed, Shaza Abdel-Halim; Abd Al Haleem, Ekram Nemr

    2013-11-01

    Nephrotoxicity is defined as renal dysfunction that arises as result of exposure to external agents such as drugs and environmental chemicals. The present work was undertaken to carry out the phytochemical study and nephroprotective activity of methanolic extract of Casuarina equisetifolia leaves in gentamicin-induced nephrotoxicity in Wistar rats. Flavonoids and phenolic acids were identified and quantified using high performance liquid chromatography. Subcutaneous injection of rats with gentamicin (80 mg/kg body weight/day) for six consecutive days induced marked acute renal toxicity, manifested by a significant increase in serum urea, creatinine and uric acid levels, along with a significant depletion of serum potassium level, compared to normal controls. Also oxidative stress was noticed in renal tissue as evidenced by a significant decrease in glutathione level, superoxide dismutase, glutathione-S-transferase activities, also a significant increase in malondialdehyde and nitric oxide levels when compared to control group. Administration of plant extract at a dose of 300 mg/kg once daily for 4 weeks restored normal renal functions and attenuated oxidative stress. In conclusion, Casuarina equisetifolia leaves extract ameliorates gentamicin-induced nephrotoxicity and oxidative damage by scavenging oxygen free radicals, decreasing lipid peroxidation and improving intracellular antioxidant defense, thus extract may be used as nephroprotective agent.

  5. Determination of gentamicin sulfate and related compounds by high-performance liquid chromatography with evaporative light scattering detection.

    Science.gov (United States)

    Clarot, I; Chaimbault, P; Hasdenteufel, F; Netter, P; Nicolas, A

    2004-03-26

    A rapid and simple method for the separation and quantitation of gentamicin sulfate by HPLC coupled with evaporative light scattering detection (ELSD) has been developed. Detection of the different components of gentamicin is problematic because of the lack of UV absorbing chromophore. The use of the universal ELSD avoids the need for sample derivatization or use of specific detector such as pulsed amperometry. Separation was performed on a highpurity C18 125 mm x 4 mm i.d., 3 microm, reversed phase column with 48.5 mM trifluoroacetic acid-methanol (97:3, v/v), as mobile phase at a flow rate of 0.7 ml/min. The influence of the gas nature, gas pressure and temperature of the drift tube of the detector on the detection response was investigated. Optimization was performed with the help of a specific experimental design software. This method allows the determination of the composition in components C1, C1a, C2, C2a and C2b of gentamicin sulfate samples. Mass spectrometry was employed to confirm the ELSD chromatographic profile. The method was validated using methodology described by the International Conference of Harmonization in the field of Medicinal Substances. Commercial samples of different sources were analyzed and results were in good agreement with specifications of both European and United States Pharmacopoeia.

  6. [Preliminary results of antibiotic resistance monitoring in the Netherlands].

    Science.gov (United States)

    Mevius, D J; Veldman, K T; van der Giessen, A; van Leeuwen, W J

    2000-03-01

    Qualitative tests are used to monitor antimicrobial resistance in bacteria of animal origin in the Netherlands. Quantitative information on trends in resistance is thus not obtained. Moreover, in general a limited panel of antibiotics is tested. The present study describes resistance in zoonotic food-borne pathogens Salmonella, Campylobacter, and Escherichia coli O157 isolated from human clinical cases and from faeces of healthy food animals in 1998 and 1999, as determined with quantitative susceptibility tests. The resistance of the indicator organisms E. coli and Enterococcus faecium isolated from faecal samples of broilers and pigs randomly sampled at slaughterhouses was also determined. For this end, faecal samples from veal calves were sampled in 1996 and 1997 at the three main Dutch veal calf slaughterhouses. In 1998 only a limited number of faecal samples of veal calves were taken at farms. For E. coli and Salmonella the following antibiotics were tested: amoxicillin, amoxicillin-clavulanic acid, piperacillin, cefotaxime, ceftazidime, imipenem, gentamicin, doxycycline, trimethoprim, trimethoprim/sulphamethoxazole, ciprofloxacin, chloramphenicol, florfenicol, carbadox, and flumequine. For E. faecium the following antibiotics were tested: amoxicillin, amoxicillin-clavulanic acid, chloramphenicol, doxycycline, erythromycin, vancomycin, teicoplanin, streptomycin ('high level' > 2000 mg/ml), gentamicin ('high level' > 500 mg/ml), ciprofloxacin, bacitracin, flavofosfolipol, salinomycin, quinupristin-dalfopristin, virginiamycin, tilmicosin, avilamycin, and everninomycin. For Campylobacter the following antibiotics were tested: erythromycin, doxycycline, gentamicin, carbadox, flavofosfolipol, ciprofloxacin, trimethoprim/sulphamethoxazole, amoxicillin, and metronidazole.

  7. Recent Advances in Nonpolar and Semipolar InGaN Light-Emitting Diodes (LEDs).

    Science.gov (United States)

    Jang, Jongjin; Woo, Seohwi; Min, Daehong; Nam, Okhyun

    2015-03-01

    The III-nitrides have attracted much attention because of their applicability in optoelectronic devices, whose emission wavelengths range from green to ultraviolet light due to their wide band gap. However, conventional c-plane GaN-based devices are influenced significantly by spontaneous and piezoelectric polarization effects, which could pose a limitation for increased luminous efficiency as a result of the quantum confined stark effect. Since the early 2000s, many groups have tried to solve these problems by examining the growth of GaN on non- or semipolar surface planes. High power non- and semipolar LEDs can be realized by the growth of a thick active layer. In addition, it is expected that it is possible to grow nonpolar InGaN LEDs with high quality p-GaN layers due to lower hole activation energy, and also long-wavelength semipolar InGaN LEDs because of the capacity for high indium incorporation in the quantum wells (QWs). However, non- and semipolar structures grown on sapphire substrate usually contain a high density of basal stacking faults and threading dislocations. For this reason, the growth of non- and semipolar GaN-based LEDs on a sapphire substrate has been attempted through the introduction of defect reduction techniques such as epitaxial lateral overgrowth, patterned sapphire substrate and re-growth techniques on a porous GaN layer, etc. Also, some researchers have grown high quality non- and semipolar GaN-based LEDs using non- and semipolar freestanding GaN substrates. In this review paper, we introduce and discuss recent progress in the development of non- and semipolar GaN-based LEDs and freestanding GaN substrates.

  8. Schottky contact formation on polar and non-polar AlN

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Pramod; Bryan, Isaac; Bryan, Zachary; Tweedie, James; Kirste, Ronny; Collazo, Ramon; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)

    2014-11-21

    The interfaces of m- and c-plane AlN with metals of different work functions and electro-negativities were characterized and the Schottky barrier heights were measured. The Schottky barrier height was determined by measuring the valence band maximum (VBM) with respect to the Fermi level at the surface (interface) before (after) metallization. VBM determination included accurate modeling and curve fitting of density of states at the valence band edge with the XPS data. The experimental behavior of the barrier heights could not be explained by the Schottky-Mott model and was modeled using InterFace-Induced Gap States (IFIGS). A slope parameter (S{sub X}) was used to incorporate the density of surface states and is a measure of Fermi level pinning. The experimental barriers followed theoretical predictions with a barrier height at the surface Fermi level (Charge neutrality level (CNL)) of ∼2.1 eV (∼2.7 eV) on m-plane (c-plane) and S{sub X} ∼ 0.36 eV/Miedema unit. Slope parameter much lower than 0.86 implied a surface/interface states dominated behavior with significant Fermi level pinning and the measured barrier heights were close to the CNL. Titanium and zirconium provided the lowest barriers (1.6 eV) with gold providing the highest (2.3 eV) among the metals analyzed on m-plane. It was consistently found that barrier heights decreased from metal polar to non-polar surfaces, in general, due to an increasing CNL. The data indicated that charged IFIGS compensate spontaneous polarization charge. These barrier height and slope parameter measurements provided essential information for designing Schottky diodes and other contact-based devices on AlN.

  9. Foaming properties of monoglycerol fatty acid esters in nonpolar oil systems.

    Science.gov (United States)

    Shrestha, Lok Kumar; Aramaki, Kenji; Kato, Hiroyuki; Takase, Yoshihiko; Kunieda, Hironobu

    2006-09-26

    Foaming properties of monoglycerol fatty acid esters that have different alkyl chain lengths were studied in different nonpolar oils, namely liquid paraffin (LP 70), squalane, and squalene. The effect of the hydrocarbon chain length of the surfactant, the concentration, the nature of the oil, and the temperature on the nonaqueous foam stability was mainly studied. Five weight percent of glycerol alpha-monododecanoate (monolaurin) formed highly stable foams in squalane at 25 degrees C, and the foams were stable for more than 14 h. Foam stability of the monolaurin/LP 70 and the monolaurin/squalene systems are almost similar, and the foams were stable for more than 12 h. Foam stability was decreased as the hydrocarbon chain length of the monoglyceride decreased. In the glycerol alpha-monodecanoate (monocaprin)-oil systems, the foams were stable only for 3-4 h, depending on the nature of the oil. However, the foams formed in the glycerol alpha-monooctanoate (monocaprylin)-oil systems coarsened very quickly, leading to the progressive destruction of foam films, and all of the foams collapsed within a few minutes. Foam stability decreased when the oil was changed from squalane to squalene, in both monocaprin and monolaurin systems. It was observed that, in the dilute regions, these monoglycerides form fine solid dispersions in the aforementioned oils at 25 degrees C. At higher temperatures, the solid melts to isotropic single-liquid or two-liquid phases and the foams formed collapsed within 5 min. Judging from the wide-angle X-ray scattering (WAXS) and the foaming test, it is concluded that the stable foams are mainly caused by the dispersion of the surfactant solids (beta-crystal) and foam stability is largely influenced by the shape and size of the dispersed solid particles.

  10. Nitrobenzene anti-parallel dimer formation in non-polar solvents

    Directory of Open Access Journals (Sweden)

    Toshiyuki Shikata

    2014-06-01

    Full Text Available We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz, which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime, respectively. The fast mode was simply attributed to the rotational motion of the (monomeric NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz2, due to a strong dipole-dipole interaction between nitro groups.

  11. Sida rhomboidea.Roxb leaf extract ameliorates gentamicin induced nephrotoxicity and renal dysfunction in rats.

    Science.gov (United States)

    Thounaojam, Menaka C; Jadeja, Ravirajsinh N; Devkar, Ranjitsinh V; Ramachandran, A V

    2010-10-28

    Sida rhomboidea.Roxb (SR) known as "Mahabala" in Ayurveda and marketed as "Shahadeyi" is used in ethnomedicine to treat ailments such as dysuria and urinary disorders. To evaluate nephroprotective potential of SR against gentamicin (GM) induced nephrotoxicity and renal dysfunction. Nephrotoxicity was induced in rats with GM (100 mg/kg bodyweight (i.p.) for 8 days) and were treated with SR extract (200 and 400 mg/kg bodyweight (p.o.) for 8 days) or 0.5% carboxymethyl cellulose (vehicle). Plasma and urine urea and creatinine, renal enzymatic and non-enzymatic antioxidants along with lipid peroxidation were evaluated in various experimental groups. GM treatment induced significant elevation (p<0.05) in plasma and urine urea, creatinine, renal lipid peroxidation along with significant decrement (p<0.05) in renal enzymatic and non-enzymatic antioxidants. SR treatment to GM treated rats (GM+SR) recorded significant decrement (p<0.05) in plasma and urine urea and creatinine, renal lipid peroxidation along with significant increment (p<0.05) in renal enzymatic and non-enzymatic antioxidants. SR leaf extract ameliorates GM induced nephrotoxicity and renal dysfunction and thus validates its ethnomedicinal use. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  12. Gentamicin sulfate-loaded porous natural rubber films for wound dressing.

    Science.gov (United States)

    Phaechamud, Thawatchai; Issarayungyuen, Pongsathorn; Pichayakorn, Wiwat

    2016-04-01

    Antimicrobial wound dressings have been developed for effectiveness of wound therapy. In this study, gentamicin sulfate was loaded into modified porous natural rubber films. The hydrophilic porous structure in natural rubber films was formed when the polar liquid such as glycerin or triethyl citrate and hydrophilic xanthan gum were blended. Film properties including morphology, drug release, water sorption and erosion, mechanical property, adhesive property, surface free energy, water vapor transmission rate, oxygen permeation, and antimicrobial activity were determined. The angiogenesis activity of films was investigated using chick chorio-allantoic membrane assay. For the system containing triethyl citrate, bi-layers comprising of a dense-top layer and a high porous-bottom layer were observed. Xanthan gum enhanced the water sorption capacity and modified to obtain the optimum rate of the drug release from the film. The developed film topography with dense-top layer induced the low adhesive property, water vapor and oxygen permeability whereas demonstrated good antimicrobial activities against Staphylococcus aureus and Pseudomonas aeruginosa with angiogenic activity. Therefore it had the potential use for medicated wound dressing.

  13. Melatonin prevents gentamicin-induced testicular toxicity and oxidative stress in rats.

    Science.gov (United States)

    Kim, S-H; Lee, I-C; Baek, H-S; Shin, I-S; Moon, C; Kim, S-H; Yun, W-K; Nam, K-H; Kim, H-C; Kim, J-C

    2014-01-01

    This study investigated the protective effects of melatonin (MT) against gentamicin (GM)-induced testicular toxicity and oxidative damage in rats. GM (100 mg kg(-1) ) was injected intraperitoneally (i.p.) to rats for 6 days. MT (15 mg kg(-1) ) was administered i.p. to rats for 6 days at 1 hr after the GM treatment. GM caused a decrease in prostate and seminal vesicle weights, sperm count and sperm motility. Histopathological examination showed various morphological alterations in the testis, characterised by degeneration of spermatogonia/spermatocytes, decrease in the number of early spermatogenic cells and vacuolisation. In addition, an increased malondialdehyde concentration and decreased glutathione content and glutathione reductase, catalase and glutathione-S-transferase activities were found in the testis. In contrast, MT treatment significantly attenuated the testicular toxicity of GM, including decreased reproductive organ weights, sperm count, and sperm motility and increased histopathological alterations. MT also had an antioxidant benefit by decreasing the lipid peroxidative product malondialdehyde and increasing the level of the antioxidant glutathione and the activities of antioxidant enzymes in the testis. These results indicate that MT prevents testicular toxicity induced by GM in rats, presumably due to its potent antioxidant activity, and its ability to inhibit lipid peroxidation, and restore antioxidant enzyme activity.

  14. Gentamicin rapidly inhibits mitochondrial metabolism in high-frequency cochlear outer hair cells.

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    Heather C Jensen-Smith

    Full Text Available Aminoglycosides (AG, including gentamicin (GM, are the most frequently used antibiotics in the world and are proposed to cause irreversible cochlear damage and hearing loss (HL in 1/4 of the patients receiving these life-saving drugs. Akin to the results of AG ototoxicity studies, high-frequency, basal turn outer hair cells (OHCs preferentially succumb to multiple HL pathologies while inner hair cells (IHCs are much more resilient. To determine if endogenous differences in IHC and OHC mitochondrial metabolism dictate differential sensitivities to AG-induced HL, IHC- and OHC-specific changes in mitochondrial reduced nicotinamide adenine dinucleotide (NADH fluorescence during acute (1 h GM treatment were compared. GM-mediated decreases in NADH fluorescence and succinate dehydrogenase activity were observed shortly after GM application. High-frequency basal turn OHCs were found to be metabolically biased to rapidly respond to alterations in their microenvironment including GM and elevated glucose exposures. These metabolic biases may predispose high-frequency OHCs to preferentially produce cell-damaging reactive oxygen species during traumatic challenge. Noise-induced and age-related HL pathologies share key characteristics with AG ototoxicity, including preferential OHC loss and reactive oxygen species production. Data from this report highlight the need to address the role of mitochondrial metabolism in regulating AG ototoxicity and the need to illuminate how fundamental differences in IHC and OHC metabolism may dictate differences in HC fate during multiple HL pathologies.

  15. Autophagic flux, a possible mechanism for delayed gentamicin-induced ototoxicity

    Science.gov (United States)

    Kim, Yeon Ju; Tian, Chunjie; Kim, Jangho; Shin, Beomyong; Choo, Oak-Sung; Kim, You-Sun; Choung, Yun-Hoon

    2017-01-01

    Aminoglycoside antibiotics including gentamicin (GM) induce delayed ototoxic effects such as hearing loss after long-term use, unlike the early-onset ototoxicity caused by cisplatin. The purpose of the study was to identify the mechanism of the delayed GM-induced ototoxicity by exploring the role of autophagy in vitro and in vivo. Treating HEI-OC1 auditory cells with GM led to a time-dependent increase of the autophagosome marker LC3-II, which was accompanied by cell death. In contrast, cisplatin and penicillin caused a rapid increase and had no effect on LC3-II levels, respectively. LC3-II-expressing autophagosomes co-localized with the labeled GM. GM-treated autophagosomes expressed reduced levels of Rab7, which is necessary for the fusion of autophagosomes with lysosomes. When the autophagic flux enhancer rapamycin was applied to GM-treated cells, Rab7 and the lysosomal enzyme cathepsin D were upregulated, and increased cell survival was observed. In animal studies, the intraperitoneal injection of GM worsened hearing thresholds and induced the accumulation of LC3 in the organ of Corti. This hearing impairment was attenuated by rapamycin. These findings suggest that the delayed onset-ototoxicity of GM may be closely related to the accumulation of autophagosomes via impaired autophagy. This GM-induced auditory cell death could be inhibited by enhancing autophagic flux. PMID:28145495

  16. Transient ischemia/hypoxia enhances gentamicin ototoxicity via caspase-dependent cell death pathway.

    Science.gov (United States)

    Lin, Chia-Der; Kao, Ming-Ching; Tsai, Ming-Hsui; Lai, Chih-Ho; Wei, I-Hua; Tsai, Mang-Hung; Tang, Chih-Hsin; Lin, Cheng-Wen; Hsu, Chuan-Jen; Lin, Ching-Yuang

    2011-07-01

    Aminoglycoside ototoxicity is a common cause of drug-induced hearing loss. Toxicity is dose related, but some patients may still develop hearing loss even under safe dosage. Apart for genetic idiosyncrasy, indirect evidences imply that ischemia may increase the aminoglycoside ototoxic sensitivity because common clinical situations associated with cochlear ischemia such as noise, sepsis, and shock are known to augment the development of aminoglycoside ototoxicity. At present, a direct interaction of cochlear ischemia and aminoglycoside ototoxicity is still lacking. This study demonstrated a direct evidence of increased gentamicin (GM) ototoxic sensitivity in chronic guinea pig models of transient cochlear ischemia. No permanent auditory changes were observed after a single dose of GM (125 mg/kg) or after transient cochlear ischemia for 30 min. Persistent and significant auditory threshold shift was detected when GM was given after transient cochlear ischemia. Cochlear hair cells and spiral ganglion neurons are the major regions affected. Apoptosis contributes to hair cell death during acute interaction of ischemia and GM ototoxicity. Increased apoptotic cell death was also depicted when GM crossreacted with hypoxia in vitro, using cochlear cell lines. Generation of reactive oxygen species, loss of mitochondrial membrane potential, calcium release, and caspase-dependent apoptotic cell death were shown during the interaction of hypoxia and GM ototoxicity in vitro. This synergistic ototoxicity may be critical to aminoglycoside-induced hearing loss in clinical scenarios. The results should improve our understanding of the interacting mechanism and potential preventive strategy to aminoglycoside ototoxicity.

  17. Administration of BMSCs with muscone in rats with gentamicin-induced AKI improves their therapeutic efficacy.

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    Pengfei Liu

    Full Text Available The therapeutic action of bone marrow-derived mesenchymal stem cells (BMSCs in acute kidney injury (AKI has been reported by several groups. However, recent studies indicated that BMSCs homed to kidney tissues at very low levels after transplantation. The lack of specific homing of exogenously infused cells limited the effective implementation of BMSC-based therapies. In this study, we provided evidence that the administration of BMSCs combined with muscone in rats with gentamicin-induced AKI intravenously, was a feasible strategy to drive BMSCs to damaged tissues and improve the BMSC-based therapeutic effect. The effect of muscone on BMSC bioactivity was analyzed in vitro and in vivo. The results indicated that muscone could promote BMSC migration and proliferation. Some secretory capacity of BMSC still could be improved in some degree. The BMSC-based therapeutic action was ameliorated by promoting the recovery of biochemical variables in urine or blood, as well as the inhibition of cell apoptosis and inflammation. In addition, the up-regulation of CXCR4 and CXCR7 expression in BMSCs could be the possible mechanism of muscone amelioration. Thus, our study indicated that enhancement of BMSCs bioactivities with muscone could increase the BMSC therapeutic potential and further developed a new therapeutic strategy for the treatment of AKI.

  18. Curcumin Attenuates Gentamicin-Induced Kidney Mitochondrial Alterations: Possible Role of a Mitochondrial Biogenesis Mechanism

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    Mario Negrette-Guzmán

    2015-01-01

    Full Text Available It has been shown that curcumin (CUR, a polyphenol derived from Curcuma longa, exerts a protective effect against gentamicin- (GM- induced nephrotoxicity in rats, associated with a preservation of the antioxidant status. Although mitochondrial dysfunction is a hallmark in the GM-induced renal injury, the role of CUR in mitochondrial protection has not been studied. In this work, LLC-PK1 cells were preincubated 24 h with CUR and then coincubated 48 h with CUR and 8 mM GM. Treatment with CUR attenuated GM-induced drop in cell viability and led to an increase in nuclear factor (erythroid-2-related factor 2 (Nrf2 nuclear accumulation and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α cell expression attenuating GM-induced losses in these proteins. In vivo, Wistar rats were injected subcutaneously with GM (75 mg/Kg/12 h during 7 days to develop kidney mitochondrial alterations. CUR (400 mg/Kg/day was administered orally 5 days before and during the GM exposure. The GM-induced mitochondrial alterations in ultrastructure and bioenergetics as well as decrease in activities of respiratory complexes I and IV and induction of calcium-dependent permeability transition were mostly attenuated by CUR. Protection of CUR against GM-induced nephrotoxicity could be in part mediated by maintenance of mitochondrial functions and biogenesis with some participation of the nuclear factor Nrf2.

  19. Curcumin Attenuates Gentamicin-Induced Kidney Mitochondrial Alterations: Possible Role of a Mitochondrial Biogenesis Mechanism.

    Science.gov (United States)

    Negrette-Guzmán, Mario; García-Niño, Wylly Ramsés; Tapia, Edilia; Zazueta, Cecilia; Huerta-Yepez, Sara; León-Contreras, Juan Carlos; Hernández-Pando, Rogelio; Aparicio-Trejo, Omar Emiliano; Madero, Magdalena; Pedraza-Chaverri, José

    2015-01-01

    It has been shown that curcumin (CUR), a polyphenol derived from Curcuma longa, exerts a protective effect against gentamicin- (GM-) induced nephrotoxicity in rats, associated with a preservation of the antioxidant status. Although mitochondrial dysfunction is a hallmark in the GM-induced renal injury, the role of CUR in mitochondrial protection has not been studied. In this work, LLC-PK1 cells were preincubated 24 h with CUR and then coincubated 48 h with CUR and 8 mM GM. Treatment with CUR attenuated GM-induced drop in cell viability and led to an increase in nuclear factor (erythroid-2)-related factor 2 (Nrf2) nuclear accumulation and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) cell expression attenuating GM-induced losses in these proteins. In vivo, Wistar rats were injected subcutaneously with GM (75 mg/Kg/12 h) during 7 days to develop kidney mitochondrial alterations. CUR (400 mg/Kg/day) was administered orally 5 days before and during the GM exposure. The GM-induced mitochondrial alterations in ultrastructure and bioenergetics as well as decrease in activities of respiratory complexes I and IV and induction of calcium-dependent permeability transition were mostly attenuated by CUR. Protection of CUR against GM-induced nephrotoxicity could be in part mediated by maintenance of mitochondrial functions and biogenesis with some participation of the nuclear factor Nrf2.

  20. A novel multidrug resistance plasmid isolated from an Escherichia coli strain resistant to aminoglycosides.

    Science.gov (United States)

    Sun, Hui; Li, Shasha; Xie, Zhijing; Yang, Fangfang; Sun, Yani; Zhu, Yanli; Zhao, Xiaomin; Jiang, Shijin

    2012-07-01

    Previous studies have reported several different plasmids that confer multidrug resistance (MDR) including resistance to aminoglycosides. In this study, we investigated the aminoglycoside resistance patterns for 224 Escherichia coli isolates from diseased chickens and ducks in China, characterized a novel MDR plasmid, and collected prevalence data on similar resistance plasmids. Antibiotic susceptibilities were determined using disc diffusion and the microdilution method. The plasmid pXZ was analysed by restriction fragment length polymorphism (RFLP) with EcoRI and SalI, and sequenced. The prevalence of similar resistance plasmids was assessed by multiplex PCR and by RFLP analysis. Among the 224 E. coli isolates, 189 (84.4%) were resistant to streptomycin, 125 (55.8%) were resistant to kanamycin, 116 (51.8%) were resistant to gentamicin, 106 (47.3%) were resistant to neomycin and 98 (43.8%) were resistant to amikacin. Among the 224 E. coli isolates, 17 contained a plasmid with the MDR-encoding region of pXZ, which showed high-level resistance to aminoglycosides (MICs of gentamicin and amikacin ≥ 512 mg/L). The plasmid pXZ was digested into five fragments by EcoRI and six fragments by SalI. The plasmid pXZ was a circular DNA molecule of 76635 bp with a 51.65% guanine + cytosine content and included four resistance genes (rmtB, fosA3, bla(TEM-1) and bla(CTX-M-24)). A novel MDR plasmid, pXZ, harbouring four resistance genes (rmtB, fosA3, bla(TEM-1) and bla(CTX-M)) was identified. To our knowledge, this is the first report of an aminoglycoside resistance plasmid harbouring the fosA3 gene.

  1. Gentamicin-loaded poly(lactic-co-glycolic acid) microparticles for the prevention of maxillofacial and orthopedic implant infections

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Claudia [Univ. Lille, 59000 Lille (France); INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, 59000 Lille (France); Degoutin, Stephanie [Univ. Lille, 59000 Lille (France); UMET, Ingénierie des Systèmes Polymères, Université de Lille 1, 59655 Villeneuve d' Ascq (France); Chai, Feng [Univ. Lille, 59000 Lille (France); INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, 59000 Lille (France); Raoul, Gwenael [Univ. Lille, 59000 Lille (France); INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, 59000 Lille (France); Service Chirurgie Maxillo-Faciale, CHRU de Lille, 59000 Lille (France); Hornez, Jean-Chritophe [Laboratoire des Matériaux Céramiques et Procédés Associés (LMCPA), Université de Valenciennes, 59300 Valenciennes (France); Martel, Bernard [Univ. Lille, 59000 Lille (France); UMET, Ingénierie des Systèmes Polymères, Université de Lille 1, 59655 Villeneuve d' Ascq (France); Siepmann, Juergen [Univ. Lille, 59000 Lille (France); INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, 59000 Lille (France); Ferri, Joel [Univ. Lille, 59000 Lille (France); INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, 59000 Lille (France); Service Chirurgie Maxillo-Faciale, CHRU de Lille, 59000 Lille (France); Blanchemain, Nicolas, E-mail: nicolas.blanchemain@univ-lille2.fr [Univ. Lille, 59000 Lille (France); INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, 59000 Lille (France)

    2016-07-01

    Trauma and orthopedic surgery can cause infections as any open surgical procedures. Such complications occur in only1 to 5% of the cases, but the treatment is rather complicated due to bacterial biofilm formation and limited drug access to the site of infection upon systemic administration. An interesting strategy to overcome this type of complications is to prevent bacterial proliferation and biofilm formation via the local and controlled release of antibiotic drugs from the implant itself. Obviously, the incorporation of the drug into the implant should not affect the latter's biological and mechanical properties. In this context, we optimized the preparation process for gentamicin-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles, which can be incorporated in the macropores of calcium phosphate-based bone substitutes. Microparticles were prepared using a double emulsion solvent extraction/evaporation technique. The processing parameters were optimized in order to provide an average microparticle size of about 60 μm, allowing for incorporation inside the macropores (100 μm) of the hydroxyapatite scaffold. Gentamicin-loaded PLGA microparticles showed a sustained release for 25–30 days and a rapid antibacterial activity due to a burst effect, the extent of which was controlled by the initial loading of the microparticles. SEM pictures revealed a highly porous microparticle structure, which can help to reduce the micro environmental pH drop and autocatalytic effects. The biological evaluation showed the cytocompatibility and non-hemolytic property of the microparticles, and the antibacterial activity against Staphylococcus aureus under the given conditions. - Highlights: • The optimization of microparticle preparation parameters allows to obtain a size compatible with the bone substitute porosity • PDL% has a direct impact on the burst effect, a control release of gentamicin was obtained • The incorporation of microparticles into the

  2. Imipenem resistance in nonfermenters causing nosocomial urinary tract infections.

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    Taneja N

    2003-07-01

    Full Text Available Nonfermenting gram-negative bacilli (nonfermenters have emerged as important nosocomial pathogens causing opportunistic infections in immunocompromised hosts. These organisms show high level of resistance to b-lactam agents, fluoroquinolones and aminoglycosides. Imipenem is a carbapenem antibiotic, which can be very useful for treatment of infections caused by nonfermenters. Eighty-five nonfermenters causing nosocomial UTI were tested for MIC to imipenem by agar dilution method. Resistance to other antimicrobial agents was compared between imipenem sensitive (S and resistance (R groups. Overall 36.4% of nonfermenters were resistant to imipenem. Forty two percent of P. aeruginosa and 18.5% of Acinetobacter baumanii were imipenem resistant. Other nonfermenters showed variable resistance, resistance in Alcaligenes spp. being very high. More than 70% of the nonfermenters were resistant to ceftazidime, gentamicin and ciprofloxacin. Piperacillin and amikacin had the best in vitro susceptibility. No significant difference was found in the antibiotic susceptibility profile among imipenem sensitive (S or resistant (R strains.

  3. Sensitive fluorimetric determination of gentamicin sulfate in biological matrices using solid-phase extraction, pre-column derivatization with 9-fluorenylmethyl chloroformate and reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Stead, D A; Richards, R M

    1996-01-26

    A high-performance liquid chromatographic method is described for the determination of gentamicin in bacterial culture medium or plasma with increased sensitivity and improved separation of the C1 component. Gentamicin was extracted from the biological matrix with high efficiency using carboxypropyl (CBA)-bonded silica. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C18 reversed-phase chromatography allowed the fluorimetric detection of gentamicins C1, C1a and C2. A fourth component, considered to be gentamicin C2a, was partially resolved from the C2 peak. Optimal conditions for the extraction and derivatization of gentamicin are described. The detection limit was below 50 micrograms/l, the assay was linear to 5 mg/l and showed good reproducibility. It is concluded that pre-column derivatization with FMOC-Cl substantially improves the analysis of gentamicin compared with present methods based on reaction with o-phthaldialdehyde.

  4. Gentamicin-induced preconditioning of proximal tubular LLC-PK1 cells stimulates nitric oxide production but not the synthesis of heat shock protein

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    E.A. Pessoa

    2009-07-01

    Full Text Available Nephrotoxicity is the main side effect of antibiotics such as gentamicin. Preconditioning has been reported to protect against injuries as ischemia/reperfusion. The objective of the present study was to determine the effect of preconditioning with gentamicin on LLC-PK1 cells. Preconditioning was induced in LLC-PK1 cells by 24-h exposure to 2.0 mM gentamicin (G/IU. After 4 or 15 days of preconditioning, cells were again exposed to gentamicin (2.0 mM and compared to untreated control or G/IU cells. Necrosis and apoptosis were assessed by acridine orange and HOESCHT 33346. Nitric oxide (NO and endothelin-1 were assessed by the Griess method and available kit. Heat shock proteins were analyzed by Western blotting. After 15 days of preconditioning, LLC-PK1 cells exhibited a significant decrease in necrosis (23.5 ± 4.3 to 6.5 ± 0.3% and apoptosis (23.5 ± 4.3 to 6.5 ± 2.1% and an increase in cell proliferation compared to G/IU. NO (0.177 ± 0.05 to 0.368 ± 0.073 µg/mg protein and endothelin-1 (1.88 ± 0.47 to 2.75 ± 0.53 pg/mL production significantly increased after 15 days of preconditioning compared to G/IU. No difference in inducible HSP 70, constitutive HSC 70 or HSP 90 synthesis in tubular cells was observed after preconditioning with gentamicin. The present data suggest that preconditioning with gentamicin has protective effects on proximal tubular cells, that involved NO synthesis but not reduction of endothelin-1 or production of HSP 70, HSC 70, or HSP 90. We conclude that preconditioning could be a useful tool to prevent the nephrotoxicity induced by gentamicin.

  5. Evaluation of protective effect of hydroalcoholic extract of Crocus sativus petals on preventing of gentamicin induced peliosis hepatis and hepatic telangiectasis in rats: short communication

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    Arash Omidi

    2013-02-01

    Full Text Available Peliosis hepatis is a rare liver disease characterized by blood-filled cavities scattered irregularly throughout the liver. Risk factors for peliosis include chronic illness such as AIDS, tuberculosis, cancer also use of some drugs such as anabolic steroids and azathioprine. The aim of the present study was to evaluate the curative properties of crocus sativus petals on induced peliosis hepatis in rats. Thirty two male Wistar rats (weight: 180-220 g were randomly divided into four equal groups: group 1 (healthy group received only IP normal saline, group2 received IP 80mg/kg.bw gentamicin, group3 IP 80mg/kg.bw gentamicin+ 40mg/kg crocus sativus petal extract, and group 4 was given IP 80mg/kg.bw gentamicin+ 40mg/kg crocus sativus petal extract. At the end of the experiment, the rats were anesthetized and their blood samples were collected through cardiac puncture for AST and ALT measurement.Then, the livers of the subjects were excised and fixed in formalin. It was found that AST significantly increased in gentamicin group (P<0.05 compared to the healthy group and groups treated by means of crocus sativus petal extract .Moreover, there was no significant differences between the groups administered the extract and those given gentamicin. Histologically,heterogeneous multiple blood-filled cavities were observed in gentamicin group (2 and the treatment groups (3 and 4. The results of the present study show that doses of hydroalcoholic extract of crocus sativus do not effect on peliosis hepatic and telangiectasis due to gentamicin sulfate in rats

  6. White light-emitting diodes based on nonpolar and semipolar gallium nitride orientations

    Science.gov (United States)

    Demille, Natalie Fellows

    Gallium nitride has become one of the key components when fabricating white light-emitting diodes. Its use as the blue source in conjunction with a wavelength converter such as the yellow emitting phosphor YAG:Ce 3+ is a technology that is commercially available and usable for solid state lighting applications. Currently available white phosphor-based LEDs (pcLEDs) use the basal plane of wurtzite GaN as their source. Although research over the past couple decades has developed this technology into devices with good photometric performance and high reliability, the introduction of nonbasal plane wurtzite GaN orientations have benefits over basal plane GaN that can be incorporated into the white LED. The focus of this research deals with exploring white illumination on nonpolar and semipolar planes of GaN. Light extraction techniques will be described that allowed for high output powers and efficiencies on the c-plane as well as the (1100), (10 11), and (1122) planes of GaN. With higher performing devices, white pcLEDs were fabricated on c-plane, m-plane, and the (1011) semipolar plane. The novelty in the present research is producing white LEDs with nonbasal plane diodes which exhibit optical polarization anisotropy. This feature, absent on the basal plane, allows for tuning photometric quantities both electrically and optically. This is demonstrated on pcLEDs as well as dichromatic LEDs comprised solely of InGaN diodes. As a consequence of these measurements, an apparent optical polarization was seen to be occurring in the luminescence of the YAG:Ce3+ when the system absorbed linearly polarized light. Polarized emission in YAG:Ce3+ was explored by obtaining single crystals of YAG:Ce3+ with different planar orientations. The experiments led to the conclusion that crystal orientation plays no part in the optical polarization. It is suggested that the cause is a result of electric dipole transitions given by various selection rules between the Ce 3+ ion's 4f and 5d

  7. Efficacy of ciprofloxacin-gentamicin combination therapy in murine bubonic plague.

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    Nadine Lemaître

    Full Text Available Potential benefits of combination antibiotic therapy for the treatment of plague have never been evaluated. We compared the efficacy of a ciprofloxacin (CIN and gentamicin (GEN combination therapy with that of each antibiotic administered alone (i against Yersinia pestis in vitro and (ii in a mouse model of bubonic plague in which animals were intravenously injected with antibiotics for five days, starting at two different times after infection (44 h and 56 h. In vitro, the CIN+GEN combination was synergistic at 0.5x the individual drugs' MICs and indifferent at 1x- or 2x MIC. In vivo, the survival rate for mice treated with CIN+GEN was similar to that observed with CIN alone and slightly higher than that observed for GEN alone 100, 100 and 85%, respectively when treatment was started 44 h post challenge. 100% of survivors were recorded in the CIN+GEN group vs 86 and 83% in the CIN and GEN groups, respectively when treatment was delayed to 56 h post-challenge. However, these differences were not statistically significant. Five days after the end of treatment, Y. pestis were observed in lymph nodes draining the inoculation site (but not in the spleen in surviving mice in each of the three groups. The median lymph node log(10 CFU recovered from persistently infected lymph nodes was significantly higher with GEN than with CIN (5.8 vs. 3.2, p = 0.04 or CIN+GEN (5.8 vs. 2.8, p = 0.01. Taken as the whole, our data show that CIN+GEN combination is as effective as CIN alone but, regimens containing CIN are more effective to eradicate Y. pestis from the draining lymph node than the recommended GEN monotherapy. Moreover, draining lymph nodes may serve as a reservoir for the continued release of Y. pestis into the blood - even after five days of intravenous antibiotic treatment.

  8. Efficacy of ciprofloxacin-gentamicin combination therapy in murine bubonic plague.

    Science.gov (United States)

    Lemaître, Nadine; Ricard, Isabelle; Pradel, Elizabeth; Foligné, Benoît; Courcol, René; Simonet, Michel; Sebbane, Florent

    2012-01-01

    Potential benefits of combination antibiotic therapy for the treatment of plague have never been evaluated. We compared the efficacy of a ciprofloxacin (CIN) and gentamicin (GEN) combination therapy with that of each antibiotic administered alone (i) against Yersinia pestis in vitro and (ii) in a mouse model of bubonic plague in which animals were intravenously injected with antibiotics for five days, starting at two different times after infection (44 h and 56 h). In vitro, the CIN+GEN combination was synergistic at 0.5x the individual drugs' MICs and indifferent at 1x- or 2x MIC. In vivo, the survival rate for mice treated with CIN+GEN was similar to that observed with CIN alone and slightly higher than that observed for GEN alone 100, 100 and 85%, respectively when treatment was started 44 h post challenge. 100% of survivors were recorded in the CIN+GEN group vs 86 and 83% in the CIN and GEN groups, respectively when treatment was delayed to 56 h post-challenge. However, these differences were not statistically significant. Five days after the end of treatment, Y. pestis were observed in lymph nodes draining the inoculation site (but not in the spleen) in surviving mice in each of the three groups. The median lymph node log(10) CFU recovered from persistently infected lymph nodes was significantly higher with GEN than with CIN (5.8 vs. 3.2, p = 0.04) or CIN+GEN (5.8 vs. 2.8, p = 0.01). Taken as the whole, our data show that CIN+GEN combination is as effective as CIN alone but, regimens containing CIN are more effective to eradicate Y. pestis from the draining lymph node than the recommended GEN monotherapy. Moreover, draining lymph nodes may serve as a reservoir for the continued release of Y. pestis into the blood - even after five days of intravenous antibiotic treatment.

  9. Beneficial effects of calcium oral coadministration in gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    Stojiljkovic, Nenad; Stoiljkovic, Milan; Mihailovic, Dragan; Randjelovic, Pavle; Ilic, Sonja; Gocmanac-Ignjatovic, Marija; Veljkovic, Milica

    2012-01-01

    Frequent therapeutical use of an aminoglycoside antibiotic gentamicin (GM) is limited by its nephrotoxic effects often characterized by both morphological and functional alterations of kidney leading to acute renal failure. The aim of this study was to examine the effect of dietary calcium supplementation on GM-induced nephrotoxicity in rats. Experiments were performed on 30 adult male Wistar rats divided into three groups of 10 animals each. G-group received GM intraperitoneally at a dose of 100 mg/kg; GCa-group received the same dose of GM concomitantly with 1 g/kg calcium carbonate given orally; and C-group, serving as control, received 1 mL/day of normal saline. All groups were treated during 8 consecutive days. Quantitative evaluation of GM-induced structural and functional changes of kidney was performed by histopathological, morphometrical, and biochemical analyses. Compared with control, G-group of rats were found to have diffusely and unequally thickened glomerular basement membrane with neutrophil cells infiltration. In addition, vacuolization of cytoplasm of proximal tubule cells with coagulation-type necrosis was observed. These GM-induced pathological lesions were significantly reduced in the rats of GCa-group. Morphometric analysis revealed statistically significant differences in the size of glomeruli (area, major and minor axes, perimeter), optical density, and roundness of glomeruli (p Biochemical analysis showed significant elevation in blood urea and serum creatinine concentrations, whereas potassium concentration was lowered in G-group compared with the other groups (p < 0.01). It is concluded that oral supplementation of calcium during treatment with GM resulted in significant reduction of morphological and functional kidney alterations.

  10. Evaluation of various gentamicin dosage regimens in geriatric patients: a simulation study.

    Science.gov (United States)

    Bourguignon, Laurent; Goutelle, Sylvain; De Saint-Martin, Julie Burdin; Maire, Pascal; Ducher, Michel

    2010-02-01

    The aim of this simulation study was to evaluate the ability of three regimens proposed in official French recommendations for gentamicin to hit defined pharmacokinetic (PK) and pharmacodynamic targets in a population of elderly patients. The first drug regimen tested consisted of a loading dose of 1 mg/kg and a maintenance dose weighted by creatininemia, every 8 h. The second regimen consisted of a fixed dose of 1 mg/kg at various intervals of time, calculated from creatinine clearance. The last regimen was a fixed dose of 3 mg/kg once a day. All regimens were for 5 days. We used a bicompartmental PK model and implemented a Monte Carlo simulation to generate a large sample of geriatric subjects. The analysis examined three ranges of creatinine clearance. Simulations showed that for the two regimens using multiple doses per day, neither was able to reach an efficacy level without significant toxicity after 5 days of treatment, regardless of the level of renal function. The use of creatininemia or creatinine clearance to adjust the drug dose did not alter these findings. The once-a-day dosing regimen gave better results both in efficacy and toxicity, except for patients with creatinine clearance lower than 60 mL/min, where the incidence of potential toxicity was above 25%. These results strongly suggest that official French recommendations about aminoglycoside dosage regimens in elderly patients with renal impairment should be updated, and that the frequent need for therapeutic drug monitoring and dosage individualization should be clearly stated.

  11. Analysis of resistance, cross-resistance and antimicrobial combinations for Pseudomonas aeruginosa isolates from 1997 to 2009.

    Science.gov (United States)

    Master, Ronald N; Clark, Richard B; Karlowsky, James A; Ramirez, Julio; Bordon, Jose M

    2011-10-01

    Pseudomonas aeruginosa is a nosocomial and community-acquired pathogen associated with considerable patient morbidity and mortality. Multidrug resistance in P. aeruginosa is a concern owing to the limited therapeutic options available to treat infections due to this organism. In this study, rates of antimicrobial resistance of P. aeruginosa isolates collected by The Surveillance Network Database-USA (Eurofins Medinet, Chantilly, VA) from 1997 to 2009 were examined. The patient population and specimens were stratified according to patient setting and age as well as specimen source. Multidrug resistance was defined as resistance to three or more of the following antimicrobial agents: aztreonam; cefepime; ciprofloxacin; imipenem; gentamicin; and piperacillin/tazobactam (TZP). A total of 924740 P. aeruginosa isolates were examined in this study. Changes in resistance rates to individual antimicrobial agents were resistant P. aeruginosa to four, five and six antimicrobial agents. For isolates resistant to imipenem, aztreonam and gentamicin, ciprofloxacin had the highest cross-resistance rates. The greatest coverage against P. aeruginosa was by the combination of TZP plus amikacin (94%) followed by aztreonam plus amikacin (90%). Pseudomonas aeruginosa resistance rates remained steady or minimally declined to all antimicrobials from 1997 to 2009. Amongst the β-lactams, TZP has the greatest activity against P. aeruginosa. Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  12. The flotation of Roşia Poieni copper ore in column machine, with non-polar oils addition

    Directory of Open Access Journals (Sweden)

    Ciocani V.

    2005-11-01

    Full Text Available The most important natural resource of copper in Romania is the ore deposit of Roşia Poieni. At present, the utilization of Roşia Poieni poorphyry copper ore is possible by extraction in quarry of the mass ore and mineral processing into a technological flux with modest results for the value of metal recovery in concentrate 70-72 % and an average contents of 16,5 % Cu. Our researches were directed to studies regarding test and utilisation of special procedure of flotation – addition of the non-polar oil – applied to advanced grinding ore with column type machines.

  13. Free ion yields for nonpolar liquids exposed to 1.6-3.5 keV X-rays

    CERN Document Server

    Holroyd, R A

    1998-01-01

    The yields of free ions formed following absorption of 1.6-3.5 keV X-rays were determined for several nonpolar liquids using a conductivity technique. The yields are much less for X-rays than for gamma rays; this effect is largest for branched hydrocarbons. A minimum in yield is observed around 2 keV. The dependence of G sub f sub i sup o on X-ray energy is in good agreement with computer simulations. For tetramethylsilane a sharp dip in ion yield is observed at the Si ls -> sigma sup * resonance, indicating that the free electron yield is even less at this energy.

  14. Cefazolin-Gentamicin versus Vancomycin-Ceftazidime Eye Drops for Bacterial Corneal Ulcers; a Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Ali-Reza Dehghani

    2009-01-01

    Full Text Available

    PURPOSE: To compare the efficacy of topical cefazolin-gentamicin versus vancomycin-ceftazidime for treatment of bacterial corneal ulcers. METHODS: This randomized double-masked clinical trial was performed on consecutive patients with bacterial corneal ulcers referred to Feiz Hospital, Isfahan, Iran from 2004 to 2005. Patients were randomly assigned to cefazolin-gentamicin or vancomycin-ceftazidime eye drops in a masked fashion. Outcome measures included time for resolution of stromal infiltration, re-epithelization of the epithelial defect, and clearance of anterior chamber inflammation as well as culture results and complications. RESULTS: The study included 89 eyes of 89 patients with bacterial corneal ulcers consisting of 57 (64% male and 32 (36% female subjects. Specimens were culture-negative in 46% of cases. Forty-one eyes received cefazolin-gentamicin and 48 eyes were treated with vancomycin-ceftazidime. Time for resolution of stromal infiltration was 17.7±4.3 days versus 13.8±3.6 days (P=0.04, time to complete re-epithelization was 13.2±3.1 days versus 9.6±2.7 days (P=0.01 and time for clearing of the anterior chamber was 11.6±2.9 days versus 8.1±2.3 days (P

  15. In vitro protection of auditory hair cells by salicylate from the gentamicin-induced but not neomycin-induced cell loss.

    Science.gov (United States)

    Mazurek, Birgit; Lou, Xiangxin; Olze, Heidi; Haupt, Heidemarie; Szczepek, Agnieszka J

    2012-01-01

    Salicylate has been shown to protect animals and people from the gentamicin-induced hearing loss. The objective of our study was to determine if salicylate is otoprotective in vitro. In this fashion, we wanted to validate the use of explant culture system for future studies on the ototoxicity prevention. In addition, we wanted to find out if salicylate protects from the ototoxicity of other aminoglycosides. As a model, we used the membranous cochlear tissues containing the organ of Corti, spiral limbus and spiral ganglion neurons dissected from the cochleas of p3-p5 Wistar pups. The explants were divided into apical, medial and basal parts and cultured in presence or absence of 100μM gentamicin, 100μM neomycin and 5mM salicylate. Following the tissue fixation and staining with phalloidin-TRITC, the number of inner and outer hair cells (IHCs, OHCs) was scored under the fluorescent microscope. Presence of 5mM salicylate in explants cultures exposed to 100μM gentamicin significantly reduced the loss of IHCs and OHCs, as compared to explants exposed to gentamicin alone. In contrast, neomycin-induced auditory hair cell loss remained unaffected by the presence of salicylate. Our results corroborate earlier in vivo findings and validate the use of cochlear explants for future studies on ototoxicity and its prevention. Moreover, the inability of salicylate to prevent neomycin-induced ototoxicity implies possible differences between the mechanisms of auditory hair cell loss induced by gentamicin and neomycin.

  16. High level resistance to aminoglycosides in enterococci from Riyadh.

    Science.gov (United States)

    Al-Ballaa, S R; Qadri, S M; Al-Ballaa, S R; Kambal, A M; Saldin, H; Al-Qatary, K

    1994-07-01

    Enterococci with high level of aminoglycosides resistance are being reported from different parts of the world with increasing frequency. Treatment of infections caused by such isolates is associated with a high incidence of failure or relapse. This is attributed to the loss of the synergetic effect of aminoglycosides and cell wall active agents against isolates exhibiting this type of resistance. To determine the prevalence of enterococci with high level resistance to aminoglycosides in Riyadh, Saudi Arabia, 241 distinct clinical isolates were examined by disk diffusion method using high content aminoglycosides disks. Seventy-four isolates (30%) were resistant to one or more of the aminoglycosides tested. The most common pattern of resistance was that to streptomycin and kanamycin. Of the 241 isolates tested, 29 (12%) were resistant to high levels of gentamicin, 35 (15%) to tobramycin, 65 (27%) to kanamycin and 53 (22%) to streptomycin. The highest rate of resistance to a high level of gentamicin was found among enterococcal blood isolates (30%). Eighteen of the isolates were identified as Enterococcus faecium, 13 (72%) of these showed high level resistance to two or more of the aminoglycosides tested.

  17. Carriage of antibiotic-resistant Enterobacteriaceae in hospitalised children in tertiary hospitals in Harare, Zimbabwe.

    Science.gov (United States)

    Magwenzi, Marcelyn T; Gudza-Mugabe, Muchaneta; Mujuru, Hilda A; Dangarembizi-Bwakura, Mutsa; Robertson, Valerie; Aiken, Alexander M

    2017-01-01

    Extended-spectrum β-lactamase-producing and gentamicin resistant Enterobacteriaceae are increasingly recognised as a major cause of infection in low-income countries. We assessed the prevalence of gastrointestinal carriage of these bacteria in hospitalised children in Harare, Zimbabwe. We conducted a cohort study in paediatric inpatients at two tertiary-referral hospitals between May and July 2015. Rectal swabs and faecal samples were collected within 24 h of admission and further follow-up samples were collected on alternate days during hospitalization. Disc-based, selective and enrichment methods were used to detect carriage of these two forms of resistance. Standard methods were used to confirm resistance status and determine the susceptibility of resistant isolates to other commonly-used antibiotics. One hundred and sixty four paediatric inpatient admissions (median age = 1.0 year, IQR = 0.2-2.2years) were enrolled, and an average of 1.9 faecal samples per patient were collected. On admission, 68/164 (41%) patients had both ESBL and gentamicin-resistant Enterobacteriaceae detected, 18 (11%) had ESBL only, 17 (10%) had gentamicin resistance only and 61 (37%) had negative screening for both forms of resistance. During hospitalisation, 32/164 (20%) patients were found to have a type of resistant organism which was not present in their admission sample. We found that faecal samples and use of a selective enrichment broth enhanced the detection of resistant organisms. Amongst resistant bacteria isolated, there were high levels of resistance to ciprofloxacin and chloramphenicol, but not ertapenem. More than half of children had enteric carriage of a clinically-relevant form of antibiotic resistance on admission to public-sector hospitals in urban Zimbabwe. Additionally, a fifth of children acquired a further form of resistance during hospitalisation. Urgent action is needed to tackle the spread of antibiotic resistant enteric bacteria in African hospitals.

  18. Effect of a novel mucoadhesive polysaccharide obtained from tamarind seeds on the intraocular penetration of gentamicin and ofloxacin in rabbits.

    Science.gov (United States)

    Ghelardi, E; Tavanti, A; Celandroni, F; Lupetti, A; Blandizzi, C; Boldrini, E; Campa, M; Senesi, S

    2000-11-01

    This report describes the efficacy of a novel mucoadhesive polymer, the tamarind seed polysaccharide, as a delivery system for the ocular administration of hydrophilic and hydrophobic antibiotics. Healthy rabbits were subjected to repeated ocular instillations with either conventional gentamicin or ofloxacin or these agents viscosified with the tamarind seed polysaccharide. Administration of viscosified preparations produced antibiotic concentrations both in the aqueous humour and cornea that were significantly higher than those achieved with the drugs alone. The increased drug absorption and the prolonged drug elimination phase obtained with the viscosified formulations indicate the usefulness of the tamarind seed polysaccharide as an ophthalmic delivery system for topical administration of antibiotics.

  19. Antibiotic resistance profiles among mesophilic aerobic bacteria in Nigerian chicken litter and associated antibiotic resistance genes1.

    Science.gov (United States)

    Olonitola, Olayeni Stephen; Fahrenfeld, Nicole; Pruden, Amy

    2015-05-01

    The effect of global antibiotic use practices in livestock on the emergence of antibiotic resistant pathogens is poorly understood. There is a paucity of data among African nations, which suffer from high rates of antibiotic resistant infections among the human population. Escherichia (29.5%), Staphylococcus (15.8%), and Proteus (15.79%) were the dominant bacterial genera isolated from chicken litter from four different farms in Zaria, Nigeria, all of which contain human pathogenic members. Escherichia isolates were uniformly susceptible to augmentin and cefuroxime, but resistant to sulfamethoxazole (54.5%), ampicillin (22.7%), ciprofloxacin (18.2%), cephalothin (13.6%) and gentamicin (13.6%). Staphylococcus isolates were susceptible to ciprofloxacin, gentamicin, and sulfamethoxazole, but resistant to tetracycline (86.7%), erythromycin (80%), clindamycin (60%), and penicillin (33.3%). Many of the isolates (65.4%) were resistant to multiple antibiotics, with a multiple antibiotic resistance index (MARI) ≥ 0.2. sul1, sul2, and vanA were the most commonly detected antibiotic resistance genes among the isolates. Chicken litter associated with antibiotic use and farming practices in Nigeria could be a public health concern given that the antibiotic resistant patterns among genera containing pathogens indicate the potential for antibiotic treatment failure. However, the MARI values were generally lower than reported for Escherichia coli from intensive poultry operations in industrial nations.

  20. Vacuum-UV spectroscopy of interstellar ice analogs. II. Absorption cross-sections of nonpolar ice molecules

    CERN Document Server

    Cruz-Diaz, G A; Chen, Y -J; Yih, T -S

    2014-01-01

    Dust grains in cold circumstellar regions and dark-cloud interiors at 10-20 K are covered by ice mantles. A nonthermal desorption mechanism is invoked to explain the presence of gas-phase molecules in these environments, such as the photodesorption induced by irradiation of ice due to secondary ultraviolet photons. To quantify the effects of ice photoprocessing, an estimate of the photon absorption in ice mantles is required. In a recent work, we reported the vacuum-ultraviolet (VUV) absorption cross sections of nonpolar molecules in the solid phase. The aim was to estimate the VUV-absorption cross sections of nonpolar molecular ice components, including CH4, CO2, N2, and O2. The column densities of the ice samples deposited at 8 K were measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. We found that, as expected, solid N2 has the lowest VUV-absorption cros...

  1. Radiative recombination mechanisms in polar and non-polar InGaN/GaN quantum well LED structures

    Science.gov (United States)

    Badcock, T. J.; Ali, M.; Zhu, T.; Pristovsek, M.; Oliver, R. A.; Shields, A. J.

    2016-10-01

    We study the photoluminescence internal quantum efficiency (IQE) and recombination dynamics in a pair of polar and non-polar InGaN/GaN quantum well (QW) light-emitting diode (LED) structures as a function of excess carrier density and temperature. In the polar LED at 293 K, the variation of radiative and non-radiative lifetimes is well described by a modified ABC type model which accounts for the background carrier concentration in the QWs due to unintentional doping. As the temperature is reduced, the sensitivity of the radiative lifetime to excess carrier density becomes progressively weaker. We attribute this behaviour to the reduced mobility of the localised electrons and holes at low temperatures, resulting in a more monomolecular like radiative process. Thus we propose that in polar QWs, the degree of carrier localisation determines the sensitivity of the radiative lifetime to the excess carrier density. In the non-polar LED, the radiative lifetime is independent of excitation density at room temperature, consistent with a wholly excitonic recombination mechanism. These findings have significance for the interpretation of LED efficiency data within the context of the ABC recombination model.

  2. Effects of growth temperature on nonpolar a-plane InN grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S.B. [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore-560013 (India); Kumar, Mahesh [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Centre of Excellence in Information and Communication Technology, Indian Institute of Technology, Jodhpur-342011 (India); Sinha, Neeraj [Office of Principal Scientific Advisor, Government of India, New Delhi 110011 (India); Department of Materials Science, Gulbarga University, Gulbarga 585 106 (India); Jali, V.M. [Department of Physics, Gulbarga University, Gulbarga 585 106 (India)

    2014-04-15

    Nonpolar a-plane InN films were grown on r-plane sapphire substrate by plasma assisted molecular beam epitaxy with GaN underlayer. Effect of growth temperature on structural, morphological, and optical properties has been studied. The growth of nonpolar a-plane (1 1 -2 0) orientation was confirmed by high resolution X-ray diffraction study. The film grown at 500 C shows better crystallinity with the rocking curve FWHM 0.67 and 0.85 along [0 0 0 1] and [1 -1 0 0] directions, respectively. Scanning electron micrograph shows formation of Indium droplets at higher growth temperature. Room tem-perature absorption spectra show growth temperature dependent band gap variation from 0.74-0.81 eV, consistent with the expected Burstein-Moss effect. The rectifying behaviour of the I-V curve indicates the existence of Schottky barrier at the InN and GaN interface. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    Science.gov (United States)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ˜60 nm min-1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  4. Effects of n-alkanes on compositions of cellular non-polar lipids in Aspergillus sp. isolated from soils

    Energy Technology Data Exchange (ETDEWEB)

    Miyazima, M.; Iida, M.; Iizuka, H.

    1985-01-01

    A strain of hydrocarbon-using filamentous fungi, Aspergillus sp. No. 250-2, was grown on n-alkanes (C/sub 11/ to C/sub 16/) and glucose as the sole carbon and energy sources, and the distribution of cellular non-polar lipids was determined. The non-polar lipids were examined by thin-layer chromatography; they were sterols, sterol esters, diglycerides, triglycerides, and free fatty acids, and the major lipids were free fatty acids and triglycerides on all substrates. Free fatty acids were mainly even-chain saturated acids on all substrates. When grown on n-C/sub 11/ to 15, the unsaturated fatty acids were mainly incorporated into triglyceride, but there were saturated fatty acids with n-C/sub 16/ and glucose. The proportion of C/sub 16/.0 acid was increased markedly in n-C/sub 16/-grown cells, but C18:0 acid was increased in glucose-grown cells. Compositions of odd-chain fatty acids were slightly increased in both free fatty acids and triglycerides from n-C/sub 15/-grown cells. It is suggested that n-alkanes as substrates influenced the incorporation of fatty acids into triglyceride.

  5. Mechanism and energetics of O and O2 adsorption on polar and non-polar ZnO surfaces

    Science.gov (United States)

    Gorai, Prashun; Seebauer, Edmund G.; Ertekin, Elif

    2016-05-01

    Polar surfaces of semiconducting metal oxides can exhibit structures and chemical reactivities that are distinct from their non-polar surfaces. Using first-principles calculations, we examine O adatom and O2 molecule adsorption on 8 different known ZnO reconstructions including Zn-terminated (Zn-ZnO) and O-terminated (O-ZnO) polar surfaces, and non-polar surfaces. We find that adsorption tendencies are largely governed by the thermodynamic environment, but exhibit variations due to the different surface chemistries of various reconstructions. The Zn-ZnO surface reconstructions which appear under O-rich and H-poor environments are found to be most amenable to O and O2 adsorption. We attribute this to the fact that on Zn-ZnO, the O-rich environments that promote O adsorption also simultaneously favor reconstructions that involve adsorbed O species. On these Zn-ZnO surfaces, O2 dissociatively adsorbs to form O adatoms. By contrast, on O-ZnO surfaces, the O-rich conditions required for O or O2 adsorption tend to promote reconstructions involving adsorbed H species, making further O species adsorption more difficult. These insights about O2 adsorption on ZnO surfaces suggest possible design rules to understand the adsorption properties of semiconductor polar surfaces.

  6. Identification of aminoglycoside resistance genes by Triplex PCR in Enterococcus spp. isolated from ICUs.

    Science.gov (United States)

    Mirnejad, Reza; Sajjadi, Nikta; Masoumi Zavaryani, Sara; Piranfar, Vahhab; Hajihosseini, Maryam; Roshanfekr, Maliheh

    2016-09-01

    Early detection of antibiotic-resistant enterococci is an important part of patient treatment. Therefore, the aim of the present study was to evaluate the resistance patterns and simultaneously identify and characterise the resistance genes in Enterococcus spp. using a triplex polymerase chain reaction (PCR) method. In all, 150 consecutive Enterococcus spp were collected from several hospitals in Tehran (Iran) from January to December 2015. The Enterococcus species were identified by standard phenotypic/biochemical tests and PCR. The antimicrobial resistance patterns were determined using a disk diffusion method. The triplex PCR method was designed to identify gentamicin and other aminoglycoside resistance genes. Among the 150 Enterococcus specimens, 87 cases (58%) were Enterococcus faecalis, and 63 cases (42%) were Enterococcus faecium. The highest frequency of resistance was observed for tetracycline while the lowest was found for vancomycin. Among the identified samples, 56.9% contained the aac(6')-Ie-aph(2'')-Ia gene, 22.2% contained the aph(3')-IIIa gene, and 38.8% contained the ant(4')-?a gene. Eight percent of the isolates contained the three aminoglycoside resistance genes. Data analysis showed that there was a significant correlation between the phenotypic gentamicin resistance and the presence of the aminoglycoside resistance genes (18.9%, p Enterococcus strains had increased aminoglycoside resistance. The direct correlation between resistance genes, such as the aminoglycoside resistance factor, and phenotypic resistance was not significant (p > 0.05).

  7. Insertion sequence IS256 in canine pyoderma isolates of Staphylococcus pseudintermedius associated with antibiotic resistance.

    Science.gov (United States)

    Casagrande Proietti, P; Bietta, A; Coletti, M; Marenzoni, M L; Scorza, A V; Passamonti, F

    2012-06-15

    Staphylococcus pseudintermedius is the most frequent staphylococcal species isolated from canine pyoderma. The control of S. pseudintermedius infection is often difficult due to the expanded antimicrobial resistance phenotypes. Antibiotic resistance in staphylococcal pathogens is often associated to mobile genetic elements such as the insertion sequence IS256 that was first described as a part of the transposon Tn4001, which confers aminoglycoside resistance in Staphylococcus aureus and in Staphylococcus epidermidis. In this study a collection of 70 S. pseudintermedius isolates from canine pyoderma was used to investigate antimicrobial susceptibility to 15 antibiotics and the presence of IS256, not revealed in S. pseudintermedius yet. Antibiotic resistance profiling demonstrated that all S. pseudintermedius isolates had a multi-drug resistance phenotype, exhibiting simultaneous resistance to at least five antibiotics; indeed methicillin resistant S. pseudintermedius isolates were simultaneously resistant to at least nine antibiotics and all were also gentamicin resistant. PCR analyses revealed the presence of IS256 in 43/70 S. pseudintemedius isolates. The association between the presence of IS256 and the resistance was particularly significant for certain antibiotics: cefovecin, amikacin, gentamicin and oxacillin (χ(2)p-valuepseudintermedius isolates and its association with antibiotic resistance. Our findings suggest that S. pseudintermedius may acquire antibiotic resistance genes through mobile genetic elements which may play a predominant role in the dissemination of multi-drug resistance.

  8. Use of gentamicin-loaded collagen sponge in internal fixation of open fractures

    Institute of Scientific and Technical Information of China (English)

    Chaudhary Susheel; Sen Ramesh; Saini Uttam Chand; Soni Ashwani; Gahlot Nitesh; Singh Daljit

    2011-01-01

    Objective: To assess the outcome of immediate plate osteosynthesis via application of antibiotic impregnated collagen fleeces (gentamicin-collagen and antibiotic sponge) which gradually release antibiotic locally in the surgical treatment of open fractures presented to us 6 hours after injury. Methods: All cases were treated in our tertiary level trauma center and teaching hospital including 35 patients with open fractures who were treated by immediate open reduction and plate fixation from January 2008 to August 2010. Among them, 31 patients were available for adequate follow-up and assessment. All fractures were treated by irrigation and debridement, immediate open reduction and plate fixation along with placement of antibiotic-releasing collagen fleeces around the plate just before closure of wound. Patients were assessed to determine postoperative infection, delayed union or nonunion and development of other postoperative complications. It was hypothesized that immediate plate osteosynthesis after thorough debridement and local antibiotics would give safe and acceptable clinical results in treatment of open fractures. Results: The 31 patients with adequate final follow-up were assessed at a mean time of 40 weeks (15-160 weeks). Most fractures united primarily in an acceptable time period according to area of involvement. Local wound complications (superficial infection and skin loss) were found in 3 patients (9.67%). Deep infection was noted in 2 patients (6.45%). None of these patients needed implant removal and both fractures united in due time. Delayed union was noted in 5 patients (16.13%). No patient progressed to nonunion or implant failure in long term follow-up. Excessive scarring was developed in 2 patients (6.45%). Conclusions: Immediate plate osteosynthesis after adequate debridement and placement of collagen film eluting antibiotics locally produces excellent results regarding bone union and absence of deep infections and is a safe technique in the

  9. Antibiotic resistance and resistance genes in Escherichia coli from poultry farms, southwest Nigeria

    DEFF Research Database (Denmark)

    Adelowo, Olawale O.; Fagade, Obasola E.; Agersø, Yvonne

    2014-01-01

    Introduction: This study investigated the mechanisms of resistance in 36 E. coli isolated from waste, litter, soil and water samples collected from poultry farms in Southwestern Nigeria. Methodology: Minimum inhibitory concentration (MIC) distributions of the isolates were determined using...... the methods of the Clinical and Laboratory Standard Institute and resistance genes detected by PCR. Results: A total of 30 isolates (94%) showed resistance to more than one antimicrobial. Percentage resistance was: tetracycline 81%, sulphamethoxazole 67%, streptomycin 56%, trimethoprim 47 %, ciprofloxacin 42......%, ampicillin 36%, spectinomycin 28%, nalidixic acid 25%, chloramphenicol 22%, neomycin 14%, gentamicin 8%, amoxicillin-clavulanate, ceftiofur, cefotaxime, colistin, florfenicol and apramycin 0%. Resistance genes found among the isolates include bla-TEM (85%), sul2 (67%), sul3 (17%), aadA (65%), strA (70%), str...

  10. General Tritium Labelling of Gentamicin C by catalytic hydrogen exchange Reaction with Tritiated Water; Marcado general con tritio de la Gentamicina C por intercambio catalitico con agua triatiada

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, C.; Diaz, D.; Paz, D.

    1991-07-01

    Gentamicin C was labelled with tritium by means of a PtO2 catalyzed hydrogen exchange reaction. Under the conditions of the exchange (100 mg of gentamicin, basic form, 0,3 ml H2O-3H, and 50 mg of prereduced PtO2) the radiochemical yield was 0,24, 0,38 and 0,48 % at 120 degree celsius, for 8, 16 and 24 hours respectively. Chemical yield for purified gentamicin was about 60 %. Purification was accomplished with a cellulose column eluted with the lower phase of chloroform-methanol 17 % ammonium hydroxide (2:1:1, v/v) . Chemical purity, determined by HPLC, was 96,5 % and radiochemical one was 95. Main exchange degradation products show biological activity. (Author) 12 refs.

  11. Urine profiles and kidney histology following intravenous diatrizoate and iohexol in the degeneration phase of gentamicin nephropathy in rats. Effects on urine and serum profiles.

    Science.gov (United States)

    Thomsen, H S; Golman, K; Larsen, S; Hemmingsen, L; Skaarup, P

    1991-11-01

    Urine chemical profiles were followed for three or nine days after intravenous injection of diatrizoate, iohexol, or saline in 30 rats, where a tubulointerstitial nephropathy was induced by gentamicin given over an eight-day period. Another ten rats injected with saline served as controls. Compared to injection of saline, both iohexol and diatrizoate induced dysfunction. The excretion of the cytoplasmic enzyme lactate dehydrogenase was significantly greater following iohexol than following diatrizoate. No significant differences between the two media were shown by the various serum components examined. Among the gentamicin-treated rats, light microscopy showed prolonged occurrence of tubular necrosis and a more intensive round cell infiltration following iohexol than following diatrizoate and saline. Both contrast media induced further temporary renal dysfunction in rats with gentamicin nephropathy; iohexol induced more morphologic changes than diatrizoate.

  12. Prevalence and Antibiogram of Generic Extended-Spectrum β-Lactam-Resistant Enterobacteria in Healthy Dogs

    Directory of Open Access Journals (Sweden)

    Madubuike U. ANYANWU

    2017-03-01

    Full Text Available This study was conducted to isolate generic extended-spectrum β-lactam-resistant enterobacteria from household dogs in Nigeria, and to determine the antibacterial resistance profile of the isolates. Rectal swabs were collected from 100, randomly selected, apparently healthy household dogs. Isolation of ESBL-resistant enterobacteria was done using Mac Conkey agar supplemented with 4 µg/ml of ceftazidime. Phenotypic characterization of the isolates to generic level was done following standard biochemical methods. Phenotypic resistance of the isolates to antibacterial agents was determined using the disc diffusion method. Out of 27 ESBL-resistant enterobacterial isolates, 40.7% were Escherichia coli, 37% were Klebsiella species, 18.5% were Salmonella species, while 3.7% was Proteus species. Resistance of the E. coli isolates was 81.8% to ampicillin, 27.2% to streptomycin, 54.5% to ciprofloxacin and tetracycline, 45.4% to enrofloxacin, 90.9% to sulphamethoxazole/trimethoprim, 9.1% to amoxicillin/clavulanic acid and 0% resistant to gentamicin. Resistance of the Klebsiella isolates was 80% to ampicillin, 20% to streptomycin and amoxicillin/clavulanic acid, 30% to ciprofloxacin and enrofloxacin, 60% to tetracycline, 90% to sulphamethoxazole/trimethoprim and 10% to gentamicin. Resistance of the Salmonella isolates was 100% to sulphamethoxazole/trimethoprim, 80% to gentamicin and ampicillin, 60% to streptomycin and tetracycline, 20% to amoxicillin/clavulanic acid, and 0% to ciprofloxacin and enrofloxacin. The Proteus isolate was resistant to streptomycin and gentamycin. All the isolates were resistant to ceftazidime and cefotaxime. Resistance of the isolates to more than 3 classes of antibacterial agents tested was 81.8% for E. coli, 70% for Klebsiella and 100% for Salmonella, respectively. This study has shown that household dogs in Nigeria, are colonized by ESBL-resistant Enterobacteriaceae and are potential reservoirs and disseminators of these

  13. Conversion of polar and non-polar algae oil lipids to fatty acid methyl esters with solid acid catalysts--A model compound study.

    Science.gov (United States)

    Asikainen, Martta; Munter, Tony; Linnekoski, Juha

    2015-09-01

    Bio-based fuels are becoming more and more important due to the depleting fossil resources. The production of biodiesel from algae oil is challenging compared to terrestrial vegetable oils, as algae oil consists of polar fatty acids, such as phospholipids and glycolipids, as well as non-polar triglycerides and free fatty acids common in vegetable oils. It is shown that a single sulphonated solid acid catalyst can perform the esterification and transesterification reactions of both polar and non-polar lipids. In mild reaction conditions (60-70 °C) Nafion NR50 catalyst produces methyl palmitate (FAME) from the palmitic acid derivatives of di-, and tri-glyceride, free fatty acid, and phospholipid with over 80% yields, with the glycolipid derivative giving nearly 40% yields of FAME. These results demonstrate how the polar and non-polar lipid derivatives of algal oil can be utilised as feedstocks for biodiesel production with a single catalyst in one reaction step.

  14. Structural stability of scandium on nonpolar GaN (112{sup ¯}0) and (101{sup ¯}0) surfaces: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    González-Hernández, Rafael, E-mail: rhernandezj@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Martínez, Gustavo; López-Perez, William [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Rodriguez, Jairo Arbey [Grupo de Estudio de Materiales, Departamento de Física, Universidad Nacional de Colombia, Bogotá (Colombia)

    2014-01-01

    First-principles calculations based on density-functional theory have been implemented to study the scandium (Sc) adsorption and incorporation on nonpolar GaN (112{sup ¯}0) and (101{sup ¯}0) surfaces. It is found that Sc adatom prefers to reside at bridge positions, between the hollow and top sites, on both GaN nonpolar surfaces. In addition, calculating the relative surface energy of several Sc configurations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the Ga chemical potentials. Based on these results, we have found that incorporation of Sc adatoms in the Ga-substitutional site is energetically more favorable compared with the adsorption on the top layers. This effect leads to the formation of ScN interlayers on nonpolar GaN (112{sup ¯}0) and (101{sup ¯}0) surfaces, which reduces the dislocation densities between GaN and ScN.

  15. Stable nonpolar solvent droplet generation using a poly(dimethylsiloxane) microfluidic channel coated with poly-p-xylylene for a nanoparticle growth.

    Science.gov (United States)

    Lim, Heejin; Moon, SangJun

    2015-08-01

    Applications of microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS) have been limited to water-based analysis rather than nonpolar solvent based chemistry due to a PDMS swelling problem that occurs by the absorption of the solvents. The absorption and swelling causes PDMS channel deformation in shape, and changes the cross sectional area making it difficult to control the flow rate and concentrations of solution in PDMS microfluidic channels. We propose that poly-p-xylylene polymers (parylenes) are chemical vapors deposited on the surfaces of PDMS channels that alleviate the effect of solvents on the absorption and swelling. The parylene coated surface sustains 3 h with a small volumetric change (less than 22 % of PDMS swelling ratio). By generating an air-nonpolar solvent interface based on droplets in PDMS channel, we confirmed poly-p-xylylene coated PDMS microfluidic channels have the potential to be applicable to nanocrystal growth using nonpolar solvents.

  16. Codon-optimized antibiotic resistance gene improves efficiency of transient transformation in Frankia

    Indian Academy of Sciences (India)

    Ken-ichi Kucho; Kentaro Kakoi; Masatoshi Yamaura; Mari Iwashita; Mikiko Abe; Toshiki Uchiumi

    2013-11-01

    Frankia is a unique actinobacterium having abilities to fix atmospheric dinitrogen and to establish endosymbiosis with trees, but molecular bases underlying these interesting characteristics are poorly understood because of a lack of stable transformation system. Extremely high GC content of Frankia genome (> 70%) can be a hindrance to successful transformation. We generated a synthetic gentamicin resistance gene whose codon usage is optimized to Frankia (fgmR) and evaluated its usefulness as a selection marker using a transient transformation system. Success rate of transient transformation and cell growth in selective culture were significantly increased by use of fgmR instead of a native gentamicin resistance gene, suggesting that codon optimization improved translation efficiency of the marker gene and increased antibiotic resistance. Our result shows that similarity in codon usage pattern is an important factor to be taken into account when exogenous transgenes are expressed in Frankia cells.

  17. Induction of bacterial antibiotic resistance by mutagenic halogenated nitrogenous disinfection byproducts.

    Science.gov (United States)

    Lv, Lu; Yu, Xin; Xu, Qian; Ye, Chengsong

    2015-10-01

    Halogenated nitrogenous disinfection byproducts (N-DBPs) raise concerns regarding their mutagenicity and carcinogenicity threatening public health. However, environmental consequence of their mutagenicity has received less attention. In this study, the effect of halogenated N-DBPs on bacterial antibiotic resistance (BAR) was investigated. After exposure to bromoacetamide (BAcAm), trichloroacetonitrile (TCAN) or tribromonitromethane (TBNM), the resistance of Pseudomonas aeruginosa PAO1 to both individual and multiple antibiotics (ciprofloxacin, gentamicin, polymyxin B, rifampin, tetracycline, ciprofloxacin + gentamicin and ciprofloxacin + tetracycline) was increased, which was predominantly ascribed to the overexpression of efflux pumps. The mechanism of this effect was demonstrated to be mutagenesis through sequencing and analyzing antibiotic resistance genes. The same induction phenomena also appeared in Escherichia coli, suggesting this effect may be universal to waterborne pathogens. Therefore, more attention should be given to halogenated N-DBPs, as they could increase not only genotoxicological risks but also epidemiological risks of drinking water.

  18. Effects of Si-doping on structural, electrical, and optical properties of polar and non-polar AlGaN epi-layers

    Science.gov (United States)

    Yang, Hongquan; Zhang, Xiong; Wang, Shuchang; Wang, Yi; Luan, Huakai; Dai, Qian; Wu, Zili; Zhao, Jianguo; Cui, Yiping

    2016-08-01

    The polar (0001)-oriented c-plane and non-polar (11 2 bar 0) -oriented a-plane wurtzite AlGaN epi-layers were successfully grown on polar (0001)-oriented c-plane and semi-polar (1 1 bar 02) -oriented r-plane sapphire substrates, respectively with various Si-doping levels in a low pressure metal organic chemical vapor deposition (MOCVD) system. The morphological, structural, electrical, and optical properties of the polar and non-polar AlGaN epi-layers were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), Hall effect, and Raman spectroscopy. The characterization results show that Si dopants incorporated into the polar and non-polar AlGaN films induced a relaxation of compressive residual strain and a generation of biaxial tensile strain on the surface in consequence of the dislocation climbing. In particular, it was found that the Si-induced compressive strain relaxation in the non-polar AlGaN samples can be promoted by the structural anisotropy as compared with the polar counterparts. The gradually increased relaxation of compressive residual strain in both polar and non-polar AlGaN samples with increasing Si-doping level was attributed to the Si-induced enhancement in the opportunity for the dislocations to interact and annihilate. This implies that the crystal quality for both polar and non-polar AlGaN epi-layers can be remarkably improved by Si-doping.

  19. The in vitro antibacterial effect of S53P4 bioactive glass and gentamicin impregnated polymethylmethacrylate beads.

    Science.gov (United States)

    Gergely, István; Zazgyva, Ancuta; Man, Adrian; Zuh, Sándor György; Pop, Tudor Sorin

    2014-06-01

    Osteomyelitis is a disease that is still difficult to treat, with considerable morbidity and associated costs. The current "gold standard" in treatment - debridement and implantation of antibiotic impregnated polymethylmethacrylate (PMMA) beads - presents the disadvantage of a second surgical intervention required for the removal of the beads. We comparatively investigated the in vitro antibacterial effect of S53P4 bioactive glass (BAG) and gentamicin impregnated PMMA beads. Bacterial viability was assessed hourly by Standard Plate Count during 24 hours of incubation, by determining the number of colony forming units (CFU) of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Klebsiella pneumoniae. Both tested materials showed an antibacterial effect on all studied bacteria. In case of S. aureus, BAG granules were almost as effective as gentamicin impregnated PMMA beads, with no statistically significant differences. In contrast, PMMA beads had a superior antibacterial effect on S. epidermidis and K. pneumoniae. The antibacterial effect of BAG was greatly influenced by granule size and contact time. There was a statistically significant correlation between pH values and the number of CFU in the case of S53P4 BAG granules. As a biocompatible and biodegradable bone substitute, S53P4 bioactive glass can be a good alternative in the local management of osteomyelitis.

  20. Comparative study of the effects of gentamicin, neomycin, streptomycin and ofloxacin antibiotics on sperm parameters and testis apoptosis in rats.

    Science.gov (United States)

    Khaki, Arash; Novin, Marefat Ghaffari; Khaki, Amir Afshin; Nouri, Mohammad; Sanati, Ehsan; Nikmanesh, Mahdad

    2008-07-01

    The aim of this study was to investigate the comparative effects of aminoglycosides and fluoroquinolones on testis apoptosis and sperm parameters in rats. Fifty male Wistar rats were randomly divided into control (n = 10) and experimental (n = 40) groups. The experimental groups subdivided into four groups often. Each received 5 mg kg(-1) (IP) gentamicin, 50 mg kg(-1) (IP) neomycin, 40 mg kg(-1) (IP) streptomycin and 72 mg kg(-1) (IP) ofloxacin daily for 14 days, respectively; however, the control group just received vehicle (IP). In the fourteenth day, rats were killed and sperm analyzed for sperm parameters. Testis tissues were also prepared for TUNEL assay for detection of apoptosis. There was a significant decrease in sperm count, viability and motility in all of experimental groups when compared with control group. Although in streptomycin group these parameters were less decreased than in the other experimental groups. The apoptotic cells were significantly increased in all experimental groups when compared with those seen in the controlled group. Gentamicin, neomycin and streptomycin and ofloxacin have negative effects on sperm parameters and testis apoptosis in rats. However, these side effects are less seen in the streptomycin group. Therefore, it is recommended that usage of this drug have fewer side effects on male fertility.

  1. INTERACTIVE EFFECTS OF DIFFERENT DURATION OF LITHIUM PRETREATMENT WITH AMIKACIN AND GENTAMICIN ONAPOMORPHINE-INDUCED LICKING IN RATS

    Directory of Open Access Journals (Sweden)

    MOHAMMAD SHARIFZADEH

    2000-07-01

    Full Text Available In this study the hypothesis that aminoglycoside antibiotics and lithium may influence apomorphine-induced licking via their effects on phosphoinositide pathways and calcium stores were investigated in male rats. Subcutaneous administration of apomorphine (0.1,0.25 and 0.5 mg/kg to rats induced licking in a dose-dependent manner and the maximum response was obtained by the dose of 0.5 mg/kg of the drug. Intracerebroventricular injections of amikacin (5, 25 and 50 ug/rat and gentamicin (10, 20 and 40 ug/rat decreased the apomorphine-induced licking significantly. Pretreatment of animals with lithium (600 mg/1 for 7,14 and 21 days increased licking induced by apomorphine. The inhibitory effects of amikacin and high dose of gentamicin were not affected by lithium pretreatment for 14 and 28 days. These findings indicate the possible involvement of phosphoinositide cascade in alterations of apomorphine-induced licking by aminoglycoside antibiotics and lithium in the brain. Also it is suggested that type and dose of aminoglycoside antibiotics and duration of lithium administration probably have different effects on responses mediated by phosphoinositide hydrolysis.

  2. In vitro bactericidal activity of amoxicillin, gentamicin, rifampicin, ciprofloxacin and trimethoprim-sulfamethoxazole alone or in combination against Listeria monocytogenes.

    Science.gov (United States)

    Boisivon, A; Guiomar, C; Carbon, C

    1990-03-01

    The in vitro bactericidal activity of amoxicillin, gentamicin, rifampicin, ciprofloxacin and trimethoprim-sulfamethoxazole alone or in combination was determined against seven strains of Listeria monocytogenes by the killing curve method. Amoxicillin plus gentamicin was the most rapidly bactericidal combination, whereas trimethoprim-sulfamethoxazole was less bactericidal at 6 h but as bactericidal at 24 h. The combination of trimethoprim-sulfamethoxazole with either amoxicillin, ciprofloxacin or rifampicin did not result in antagonism, but the combinations were no more active than trimethoprim-sulfamethoxazole alone. The interaction of amoxicillin with rifampin was fairly antagonistic (1 log10 difference). The combination of amoxicillin and ciprofloxacin, although producing antagonism during the first 6 h, was more active at 24 h than amoxicillin alone and prevented the regrowth observed with ciprofloxacin alone. Ciprofloxacin and rifampicin interacted antagonistically during the first 6 h, and the combination was not very bactericidal (3 log10) but prevented the emergence of mutants, as observed with each drug alone, when used at concentrations greater than the MICs for the strain tested. These regimens merit evaluation in in vivo models of Listeria monocytogenes meningitis.

  3. Single-Dose Oral Amoxicillin or Linezolid for Prophylaxis of Experimental Endocarditis Due to Vancomycin-Susceptible and Vancomycin-Resistant Enterococcus faecalis▿

    OpenAIRE

    Moreillon, Philippe; Wilson, Walter R.; Leclercq, Roland; Entenza, José M,

    2007-01-01

    Endocarditis prophylaxis following genitourinary or gastrointestinal procedures targets Enterococcus faecalis. Prophylaxis recommendations advocate oral amoxicillin (2 g in the United States and 3 g in the United Kingdom) in moderate-risk patients and intravenous amoxicillin (2 g) or vancomycin (1 g) plus gentamicin in high-risk patients. While ampicillin-resistant (or amoxicillin-resistant) E. faecalis is still rare, there is a concern that these regimens might fail against vancomycin-resist...

  4. An Analytic Equation of State Based on SAFT-CP for Binary Non-Polar Alkane Mixtures Across the Critical Point

    Institute of Scientific and Technical Information of China (English)

    周文来; 密建国; 贺刚; 于燕梅; 陈健

    2003-01-01

    The description using an analytic equation of state of thermodynamic properties near the critical points of fluids and their mixtures remains a challenging problem in the area of chemical engineering. Based on the statistical associating fluid theory across the critical point (SAFT-CP), an analytic equation of state is established in this work for non-polar mixtures. With two binary parameters, this equation of state can be used to calculate not only vapor-liquid equilibria but also critical properties of binary non-polar alkane mixtures with acceptable deviations.

  5. Antibiotic resistance and mechanisms implicated in clinical enterococci in a Tunisian hospital.

    Science.gov (United States)

    Klibi, N; Gharbi, S; Masmoudi, A; Ben Slama, K; Poeta, P; Zarazaga, M; Fendri, C; Boudabous, A; Torres, C

    2006-02-01

    Susceptibility testing for 15 antibiotics was performed in a series of 191 clinical enterococci recovered in a Tunisian Hospital during 2000-2003. Species detected were the following ones (number of isolates): E. faecalis (139), E. faecium (41), E. casseliflavus (5), E. gallinarum (3), E. avium (2) and E. hirae (1). The percentages of antibiotic resistance detected were as follows (E. faecalis/ E. faecium/ other species) : penicillin (0/ 73/ 9%), tetracycline (78/ 44/ 54%), chloramphenicol (52/ 29/ 27%), erythromycin (66/ 100/ 82%), spiramycin (84/ 83/ 64%), pristinamycin (100/ 0/ 73%), trimethoprim-sulfamethoxazole (88/ 78/ 91%), rifampicin (72/ 41/ 0%), vancomycin (0/ 0/ 36%), teicoplanin (0/ 0/ 0%), high-level-resistance for gentamicin (24/ 29/ 45%), streptomycin (34/ 56/ 55%) and kanamycin (41/ 68/ 55%). Increased vancomycin minimum inhibitory concentrations (MICs) were only detected in E. casseliflavus and E. gallinarum isolates (MIC range 8-24 microg/ml). The erm(B), catA, tet(M), aac(6')-aph(2''), aph(3')-IIIa, and ant(6)-Ia genes were detected in 91%, 32%, 86%, 98%, 100%, and 72% of the E. faecium and E. faecalis isolates resistant to erythromycin, chloramphenicol, tetracycline and high-level-resistant to gentamicin, kanamycin and streptomycin, respectively. A total of 20 unrelated pulsed-field-gel-electrophoresis patterns were found in the series of 46 high-level gentamicin-resistant E. faecalis and E. faecium isolates of this study.

  6. Genome-wide identification of antimicrobial intrinsic resistance determinants in Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Martin Vestergaard

    2016-12-01

    Full Text Available The emergence of antimicrobial resistance severely threatens our ability to treat bacterial infections. While acquired resistance has received considerable attention, relatively little is known of intrinsic resistance that allows bacteria to naturally withstand antimicrobials. Gene products that confer intrinsic resistance to antimicrobial agents may be explored for alternative antimicrobial therapies, by potentiating the efficacy of existing antimicrobials. In this study, we identified the intrinsic resistome to a broad spectrum of antimicrobials in the human pathogen, Staphylococcus aureus. We screened the Nebraska Transposon Mutant Library of 1920 single-gene inactivations in S. aureus strain JE2, for increased susceptibility to the anti-staphylococcal antimicrobials (ciprofloxacin, oxacillin, linezolid, fosfomycin, daptomycin, mupirocin, vancomycin and gentamicin. 68 mutants were confirmed by E-test to display at least two-fold increased susceptibility to one or more antimicrobial agents. The majority of the identified genes have not previously been associated with antimicrobial susceptibility in S. aureus. For example, inactivation of genes encoding for subunits of the ATP synthase, atpA, atpB, atpG and atpH, reduced the minimum inhibitory concentration (MIC of gentamicin 16-fold. To elucidate the potential of the screen, we examined treatment efficacy in the Galleria mellonella infection model. Gentamicin efficacy was significantly improved, when treating larvae infected with the atpA mutant compared to wild type cells with gentamicin at a clinically relevant concentration. Our results demonstrate that many gene products contribute to the intrinsic antimicrobial resistance of S. aureus. Knowledge of these intrinsic resistance determinants provides alternative targets for compounds that may potentiate the efficacy of existing antimicrobial agents against this important pathogen.

  7. Use of polar and nonpolar fractions as additional information sources for studying thermoxidized virgin olive oils by FTIR

    Directory of Open Access Journals (Sweden)

    Tena, N.

    2014-09-01

    Full Text Available Fourier transform infrared (FTIR spectroscopy has been proposed to study the degradation of virgin olive oils (VOO in samples undergoing thermoxidation. The polar and nonpolar fractions of oxidized oils have been analyzed by FTIR to provide further information on the minor spectral changes taking place during thermoxidation. This information assists in the interpretation of the spectra of the samples. For this purpose polar and nonpolar fractions of 47 VOO samples thermoxidized (190 °C in a fryer were analyzed by FTIR. The time-course change of the band area assigned to single cis double bonds was explained by their correlation with the decrease in oleic acid (adjusted-R2=0.93. The bands assigned to the hydroxyl groups and the first overtone of ester groups was better studied in the spectra collected for the polar and nonpolar fractions, respectively. The bands assigned to peroxide, epoxy, tertiary alcohols and fatty acids were clearly observed in the spectra of the polar fraction while they are not noticeable in the spectra of the oils.La espectroscopía de infrarrojos por transformada de Fourier (FTIR se ha propuesto para estudiar la degradación de los aceites de oliva vírgenes (AOV sujetas a termoxidación. Las fracciones polares y no polares de aceites oxidados se analizaron mediante FTIR para obtener más información sobre los cambios espectrales menores que tienen lugar durante la termoxidación. Esa información ayuda en la interpretación de los espectros de las muestras puras. Con este objetivo, fracciones polares y no polares de 47 AOV termoxidados (190 °C en una freidora se analizaron mediante FTIR. La banda asignada a dobles enlaces cis se explica por su correlación con la disminución de ácido oleico (R2-ajustado=0,93. Las bandas asignadas a los grupos hidroxilos y del primer sobretono de los grupos éster se estudió mejor en los espectros recogidos para la fracción polar y no polar, respectivamente. Grupos asignados a per

  8. Emergence of KPC-2 and KPC-3 in Carbapenem-Resistant Klebsiella pneumoniae Strains in an Israeli Hospital▿

    OpenAIRE

    Leavitt, Azita; Navon-Venezia, Shiri; Chmelnitsky, Inna; Schwaber, Mitchell J.; Carmeli, Yehuda

    2007-01-01

    Carbapenem resistance due to KPC has rarely been observed outside the United States. We noticed a sharp increase in carbapenem-resistant Klebsiella pneumoniae strains possessing KPC in Tel Aviv Medical Center from 2004 to 2006. Sixty percent of the isolates belonged to a single clone susceptible only to gentamicin and colistin and carried the blaKPC-3 gene, while almost all other clones carried the blaKPC-2 gene. This rapid dissemination of KPC outside the United States is worrisome.

  9. Comparison of antimicrobial resistance phenotypes and resistance genes in Enterococcus faecalis and Enterococcus faecium from humans in the community, broilers and pigs in Denmark

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Agersø, Yvonne; Gerner-Smidt, P.;

    2000-01-01

    Enterococcus faecalis and E. faecium isolated from humans in the community (98 and 65 isolates), broilers (126 and 122), and pigs (102 and 88) during 1998 were tested for susceptibility to 12 different antimicrobial agents and for the presence of selected genes encoding resistance using PCR...... of the 38 human fecal samples examined using selective enrichment. All vancomycin resistant isolates contained the vanA gene, all chloramphenicol resistant isolates the catpIP501 gene, and all five gentamicin resistant isolates the aac6-aph2 gene. Sixty-one (85%) of 72 erythromycin resistant E. faecalis...... examined and 57 (90%) of 63 erythromycin resistant E. faecium isolates examined contained ermB. Forty (91%) of the kanamycin resistant E. faecalis and 18 (72%) of the kanamycin resistant E. faecium isolates contained aphA3. The tet(M) gene was found in 95% of the tetracycline resistant E. faecalis and E...

  10. Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE.

    Science.gov (United States)

    Shih, Cheng-Hung; Huang, Teng-Hsing; Schuber, Ralf; Chen, Yen-Liang; Chang, Liuwen; Lo, Ikai; Chou, Mitch Mc; Schaadt, Daniel M

    2011-06-15

    We have investigated the structure of non-polar GaN, both on the M - and A-plane, grown on LiGaO2 by plasma-assisted molecular beam epitaxy. The epitaxial relationship and the microstructure of the GaN films are investigated by transmission electron microscopy (TEM). The already reported epi-taxial relationship and for M -plane GaN is confirmed. The main defects are threading dislocations and stacking faults in both samples. For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1. In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

  11. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    Science.gov (United States)

    Smirnov, A. M.; Young, E. C.; Bougrov, V. E.; Speck, J. S.; Romanov, A. E.

    2016-01-01

    We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ˜70° for Al0.13Ga0.87N/GaN ( h 0 h ¯ 1 ) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1-xN/GaN heterostructures.

  12. Efficient Extraction of Astaxanthin from Phaffia rhodozyma with Polar and Non-polar Solvents after Acid Washing

    Institute of Scientific and Technical Information of China (English)

    YIN Chunhua; YANG Shuzhen; LIU Xiaolu; YAN Hai

    2013-01-01

    method of extracting astaxanthin from Phaffia rhodozyma with various solvents after acid washing was investigated.The extraction efficiency was distinctly increased after acid washing of P.rhodozyma cells.When the concentration of HCl was 0.4 mol·L-,the highest extraction efficiency of astaxanthin was achieved which was about three times higher than the control.Acetone or benzene as single polar or non-polar solvent was the most effective solvent in our research.With a combination of isopropanol and n-hexane (volume ratio of 2 ∶ 1),the maximal extraction efficiency was achieved,approximately 60% higher than that obtained with a single solvent.The liquid-solid ratio and the extracting time were also optimized.Under the optimum extraction conditions,the extraction yield of astaxanthin exceeded 98%.

  13. Simultaneous analysis method for polar and non-polar ginsenosides in red ginseng by reversed-phase HPLC-PAD.

    Science.gov (United States)

    Lee, Sa-Im; Kwon, Ha-Jeong; Lee, Yong-Moon; Lee, Je-Hyun; Hong, Seon-Pyo

    2012-02-23

    The paper describes the development of a simultaneous determination method for polar and non-polar ginsenosides in red ginseng with a reversed-phase high-performance liquid chromatography-pulsed amperometric detection method. This method could be applied directly without any pretreatment steps and enabled the performance of highly sensitive analysis within 1h. The detection (S/N=3) and quantification (S/N=10) limits for the ginsenosides ranged 0.02-0.10 ng and 0.1-0.3 ng, respectively. The linear regression coefficients ranged 0.9975-0.9998. Intra- and inter-day precisions were <9.91%. The mean recoveries ranged 98.08-103.06%. The total amount of ginsenosides in the hairy root of red ginseng was higher than that in the main root.

  14. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    KAUST Repository

    Smirnov, A. M.

    2016-01-20

    We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN (h0h̄ 1) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

  15. High-resolution field desorption/ionization fourier transform ion cyclotron resonance mass analysis of nonpolar molecules.

    Science.gov (United States)

    Schaub, Tanner M; Hendrickson, Christopher L; Qian, Kuangnan; Quinn, John P; Marshall, Alan G

    2003-05-01

    We report the first field desorption ionization broadband high-resolution (m/Deltam(50%) approximately 65 000) mass spectra. We have interfaced a field ionization/field desorption source to a home-built 9.4-T FT-ICR mass spectrometer. The instrumental configuration employs convenient sample introduction (in-source liquid injection) and external ion accumulation. We demonstrate the utility of this configuration by generating high-resolution positive-ion mass spectra of C(60) and a midboiling crude oil distillate. The latter contains species not accessible by common soft-ionization methods, for example, low-voltage electron ionization, electrospray ionization, and matrix-assisted laser desorption/ionization. The present work demonstrates significant advantages of FI/FD FT-ICR MS for analysis of nonpolar molecules in complex mixtures.

  16. Interaction of Polar and Nonpolar Organic Pollutants with Soil Organic Matter: Sorption Experiments and Molecular Dynamics Simulation

    CERN Document Server

    Ahmed, Ashour A; Aziz, Saadullah G; Hilal, Rifaat H; Elroby, Shaaban A; Al-Youbi, Abdulrahman O; Leinweber, Peter; Kühn, Oliver

    2014-01-01

    The fate of organic pollutants in the environment is influenced by several factors including the type and strength of their interactions with soil components especially SOM. However, a molecular level answer to the question How organic pollutants interact with SOM? is lacking. In order to explore mechanisms of this interaction, we have developed a new SOM model followed by carrying out molecular dynamics (MD) simulations in parallel with sorption experiments. The new SOM model comprises free SOM functional groups (carboxylic acid and naphthalene) as well as SOM cavities (with two different sizes), representing the soil voids, containing the same SOM functional groups. To examine the effect of the hydrophobicity on the interaction, the organic pollutants hexachlorobenzene (HCB, non-polar) and sulfanilamide (SAA, polar) were considered. The experimental and the theoretical outcomes explored four major points regarding sorption of SAA and HCB on soil. 1. The interaction depends on the SOM chemical composition mo...

  17. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    Directory of Open Access Journals (Sweden)

    A. M. Smirnov

    2016-01-01

    Full Text Available We calculate the critical thickness for misfit dislocation (MD formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs. It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN ( h 0 h ̄ 1 semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

  18. Modeling the structure and absorption spectra of stilbazolium merocyanine in polar and nonpolar solvents using hybrid QM/MM techniques.

    Science.gov (United States)

    Murugan, N Arul; Kongsted, Jacob; Rinkevicius, Zilvinas; Aidas, Kestutis; Ågren, Hans

    2010-10-28

    We have performed Car-Parrinello mixed quantum mechanics/molecular mechanics (CP-QM/MM) calculations for stilbazolium merocyanine (SM) in polar and nonpolar solvents in order to explore the role of solute molecular geometry, solvation shell structure, and different interaction mechanisms on the absorption spectra and its dependence on solvent polarity. On the basis of the average bond length values and group charge distributions, we find that the SM molecule remains in a neutral quinonoid form in chloroform (a nonpolar solvent) while it transforms to a charge-separated benzenoid form in water (a polar solvent). Based on a quantum mechanical/molecular mechanical response technique, with different MM descriptions for the water environment, absorption spectra were obtained as averages over configurations derived from the CP-QM/MM simulations. We show that for SM in water the solute polarization plays a major role in predictions of the λ(max) and solvatochromic shift and that once this effect is included the contributions from solvent polarization and intermolecular charge transfer become less important. For SM in chloroform and water solvents, we have also performed absorption spectra calculations using a polarizable continuum model in order to address its relative performance compared to the QM/MM response technique. In the case of SM in water, our study supports the notion that, in order to predict accurate absorption spectra and solvatochromic shifts, it is important to use a discrete description of the solvent when it, as in water, is involved in site-specific interaction with the solute molecule. The technique is thus shown to outperform the more conventional polarizable continuum model in predicting the solvatochromic shift.

  19. Vacuum-UV spectroscopy of interstellar ice analogs. II. Absorption cross-sections of nonpolar ice molecules

    Science.gov (United States)

    Cruz-Diaz, G. A.; Muñoz Caro, G. M.; Chen, Y.-J.; Yih, T.-S.

    2014-02-01

    Context. Dust grains in cold circumstellar regions and dark-cloud interiors at 10-20 K are covered by ice mantles. A nonthermal desorption mechanism is invoked to explain the presence of gas-phase molecules in these environments, such as the photodesorption induced by irradiation of ice due to secondary ultraviolet photons. To quantify the effects of ice photoprocessing, an estimate of the photon absorption in ice mantles is required. In a recent work, we reported the vacuum-ultraviolet (VUV) absorption cross sections of nonpolar molecules in the solid phase. Aims: The aim was to estimate the VUV-absorption cross sections of nonpolar molecular ice components, including CH4, CO2, N2, and O2. Methods: The column densities of the ice samples deposited at 8 K were measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. Results: We found that, as expected, solid N2 has the lowest VUV-absorption cross section, which about three orders of magnitude lower than that of other species such as O2, which is also homonuclear. Methane (CH4) ice presents a high absorption near Ly-α (121.6 nm) and does not absorb below 148 nm. Estimating the ice absorption cross sections is essential for models of ice photoprocessing and allows estimating the ice photodesorption rates as the number of photodesorbed molecules per absorbed photon in the ice. Data can be found at http://ghosst.osug.fr/

  20. Ampicillin Resistance and Outcome Differences in Acute Antepartum Pyelonephritis

    Science.gov (United States)

    Greer, Laura G.; Roberts, Scott W.; Sheffield, Jeanne S.; Rogers, Vanessa L.; Hill, James B.; Mcintire, Donald D.; Wendel, George D.

    2008-01-01

    Objective. To measure the incidence of ampicillin-resistant uropathogens in acute antepartum pyelonephritis and to determine if patients with resistant organisms had different clinical outcomes. Study design. This was a secondary analysis of a prospective cohort study of pregnant women admitted with pyelonephritis, diagnosed by standard clinical and laboratory criteria. All patients received ampicillin and gentamicin. Results. We identified 440 cases of acute pyelonephritis. Seventy-two percent (316 cases) had urine cultures with identification of organism and antibiotic sensitivities. Fifty-one percent of uropathogens were ampicillin resistant. The patients with ampicillin-resistant organisms were more likely to be older and multiparous. There were no significant differences in hospital course (length of stay, days of antibiotics, ECU admission, or readmission). Patients with ampicillin-resistant organisms did not have higher complication rates (anemia, renal dysfunction, respiratory insufficiency, or preterm birth). Conclusion. A majority of uropathogens were ampicillin resistant, but no differences in outcomes were observed in these patients. PMID:18923674

  1. Evaluation of efficacy of vitamin E and N-acetyl cysteine in gentamicin-induced nephrotoxicity in rats.

    Science.gov (United States)

    Patel Manali, Bhalchandra; Deshpande, Shrikalp; Shah, Gaurang

    2011-01-01

    Gentamicin (GM), an aminoglycoside, is widely employed in clinical practice for the treatment of serious gram-negative infections. The clinical utility of GM is limited by the frequent incidence of acute renal failure. This study was designed to investigate treatment and posttreatment renoprotective potential of vitamin E and N-acetyl cysteine (NAC) against GM-induced oxidative stress and renal dysfunction. Male Sprague-Dawley rats were divided into six groups: first group is the control group that received olive oil (0.1 mL/100 g B.W.), second is the one that was treated with GM (80 mg/kg/i.p./8 days), third is the one that was treated with GM (80 mg/kg/i.p./8 days) and vitamin E (50 mg/kg/i.p./8 days), fourth is the one that was treated with GM (80 mg/kg/i.p./8 days) and NAC (50 mg/kg/i.p./8 days), fifth is the one that was treated with GM (80 mg/kg/i.p./8 days), vitamin E (50 mg/kg/i.p./8 days), and NAC (50 mg/kg/i.p./8 days), and sixth is the one that was treated with GM initially for 8 days (at 80 mg/kg/i.p.) after which vitamin E (at 50 mg/kg/i.p.) and NAC (at 50 mg/kg/i.p.) were administered for 8 days. Serum creatinine, blood urea nitrogen, serum glucose, renal malondialdehyde, renal reduced glutathione, urine sodium, fractional excretion of sodium, and histopathological examination of kidney were performed after treatment. Gentamicin treatment caused nephrotoxicity as evidenced by marked elevation in serum creatinine, blood urea nitrogen, renal malondialdehyde, urine sodium, and fractional excretion of sodium. Study of renal morphology showed marked loss of epithelium in proximal convoluted tubule, inflammatory infiltrate in the form of lymphocytes, mainly in interstitium. Treatment and posttreatment with vitamin E and NAC significantly restored renal functions, reduced lipid peroxidation, enhanced reduced glutathione level, and restored the biochemical parameters. The results of this study demonstrate the therapeutic potential of vitamin E and NAC in

  2. Indium incorporation in semipolar (20 2 ̅ 1) and nonpolar (10 1 ̅ 0) InGaN grown by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Sawicka, M.; Feduniewicz-Żmuda, A.; Kryśko, M.; Turski, H.; Muziol, G.; Siekacz, M.; Wolny, P.; Skierbiszewski, C.

    2017-02-01

    Semipolar (20 2 ̅ 1) , nonpolar m-plane (10 1 ̅ 0) and polar c-plane (0001) GaN and InGaN layers were grown by plasma-assisted molecular beam epitaxy. The surface of semipolar and nonpolar GaN grown under Ga-rich conditions is very smooth. The indium incorporation efficiency in InGaN layers grown under In-rich growth conditions is studied on three surface orientations (i) as a function of temperature from 570 to 650 °C and (ii) for varied active nitrogen flux from 0.41 to 2.03 μm/h. The In content follows the relation (10 1 ̅ 0) experiments. Indium composition in InGaN layers can be increased (i) by the decrease of the growth temperature and (ii) increase of the applied nitrogen flux for all studied surface orientations. Additionally, surface morphology of semipolar, nonpolar and c-polar InGaN layers grown at 650, 640 and 620 °C is compared. No increase in surface roughness for semipolar and nonpolar InGaN was observed in contrast to c-plane counterparts.

  3. Non-polar In x Ga1-x N/GaN quantum dots: impact of dot size and shape anisotropies on excitonic and biexcitonic properties

    Science.gov (United States)

    Kanta Patra, Saroj; Schulz, Stefan

    2017-01-01

    In this work, we present a theoretical analysis of the built-in potential, the excitonic and biexcitonic properties of non-polar InGaN/GaN quantum dots by means of self-consistent Hartree calculations using \\mathbf{k}\\centerdot \\mathbf{p} theory. Special attention is paid to the impact of dot size and shape anisotropies on the results. Our calculations reveal that even though non-polar InGaN/GaN quantum dots exhibit strongly reduced built-in fields when compared to c-plane dots, the excitonic and biexcitonic properties are significantly affected by these residual fields. Furthermore, changes in the built-in field when the geometrical dot features are modified, result in an unusual variation of the exciton binding energy. All these findings highlight that the dot geometry significantly affects electronic and optical properties of non-polar InGaN/GaN systems. This is further supported by comparing our theoretical data with experimental literature results. Here, we analyze also trends in exciton and biexciton binding energies and discuss the potential use of non-polar InGaN/GaN dots for entangled photon emission via the time reordering scheme.

  4. Defensive Armor of Potato Tubers: Nonpolar Metabolite Profiling, Antioxidant Assessment, and Solid-State NMR Compositional Analysis of Suberin-Enriched Wound-Healing Tissues.

    Science.gov (United States)

    Dastmalchi, Keyvan; Kallash, Linda; Wang, Isabel; Phan, Van C; Huang, Wenlin; Serra, Olga; Stark, Ruth E

    2015-08-05

    The cultivation, storage, and distribution of potato tubers are compromised by mechanical damage and suboptimal healing. To investigate wound-healing progress in cultivars with contrasting russeting patterns, metabolite profiles reported previously for polar tissue extracts were complemented by GC/MS measurements for nonpolar extracts and quantitative (13)C NMR of interfacial solid suspensions. Potential marker compounds that distinguish cultivar type and wound-healing time point included fatty acids, fatty alcohols, alkanes, glyceryl esters, α,ω-fatty diacids, and hydroxyfatty acids. The abundant long-chain fatty acids in nonpolar extracts and solids from the smooth-skinned Yukon Gold cultivar suggested extensive suberin biopolymer formation; this hypothesis was supported by high proportions of arenes, alkenes, and carbonyl groups in the solid and among the polar markers. The absence of many potential marker classes in nonpolar Atlantic extracts and interfacial solids suggested a limited extent of suberization. Modest scavenging activities of all nonpolar extracts indicate that the majority of antioxidants produced in response to wounding are polar.

  5. Nephro-protective effect of a novel formulation of unopened coconut inflorescence sap powder on gentamicin induced renal damage by modulating oxidative stress and inflammatory markers.

    Science.gov (United States)

    Jose, Svenia P; S, Asha; Im, Krishnakumar; M, Ratheesh; Santhosh, Savitha; S, Sandya; B, Girish Kumar; C, Pramod

    2017-01-01

    Fresh oyster white translucent sap obtained from the tender unopened inflorescence of coconut trees (Cocos nucifera) is identified to have great health benefits. Drug induced Nephrotoxicity is one of the major causes of renal damage in present generation. As a therapeutic agent, gentamicin imparts direct toxicity to kidney, resulting in acute tubular necrosis, glomerular and tubulointerstitial injury, haemodynamically mediated damage and obstructive nephropathy.There exists an increasing demand for safe and natural agents for the treatment and/or preventionofchronic nephrotoxicity and pathogenesis of kidney diseases. Our study shows the nephro protective/curing effect of a novel powder formulation of micronutrient enriched, unfermented coconut flower sap (CSP). The study was performed on adult male Wistar rats. The animals were grouped into three and treated separately with vehicle, gentamicin and gentamicin+CSP for 16days. Initially, gentamicin treatment significantly (pcoconut flower sap powder showed significant (p<0.05) reversal of all these biochemical parameters indicating an effective inhibition of the pathogenesis of nephrotoxicity and kidney disease.

  6. Effects of ampicillin, gentamicin, and cefotaxime on the release of Shiga toxins from Shiga toxin-producing Escherichia coli isolated during a diarrhea episode in Faisalabad, Pakistan.

    Science.gov (United States)

    Mohsin, Mashkoor; Haque, Abdul; Ali, Aamir; Sarwar, Yasra; Bashir, Saira; Tariq, Ayesha; Afzal, Amna; Iftikhar, Tayyaba; Saeed, Muhammad Azeem

    2010-01-01

    The Shiga toxin-producing Escherichia coli (STEC) is an emerging foodborne pathogen. The proportion of cases attributed to STEC in an episode of diarrhea in the Faisalabad region of Pakistan was investigated. In addition, as increase in Shiga toxin (Stx) release after exposure to various antimicrobial agents is widely reported, we also elucidated the in vitro effects of three commonly used antibiotics (ampicillin, gentamicin, and cefotaxime) on Stx release. Isolation and detection of STEC was done using enzyme-linked immunosorbent assay and polymerase chain reaction, followed by phenotypic characterization. In vitro Stx release from isolated STEC was determined using enzyme-linked immunosorbent assay, and Stx-induced verocytotoxicity was quantified using cytotoxicity detection assay. STEC was detected in 5 (21.7%) of 23 patients. Exposure to minimum inhibitory concentration (MIC) of ampicillin, gentamicin, and cefotaxime resulted in a considerable decrease in toxin release and level of cytotoxicity in most of the STEC isolates when compared with control (without antibiotic exposure). Exposure to sub-MIC of ampicillin resulted in a relative increase in Stx release and cytotoxicity (p cefotaxime. Sub-MIC of gentamicin resulted in largest decrease in Stx release and a similar trend was observed with cefotaxime to a lesser extent. In conclusion, these in vitro observations suggested that sub-MIC of ampicillin may stimulate Stx release and level of cytotoxicity and therefore should be avoided. Gentamicin did not show such effects and therefore may be considered for STEC antimicrobial therapy.

  7. Effect of gentamicin and levels of ambient sound on hearing screening outcomes in the neonatal intensive care unit: A pilot study.

    Science.gov (United States)

    Garinis, Angela C; Liao, Selena; Cross, Campbell P; Galati, Johnathan; Middaugh, Jessica L; Mace, Jess C; Wood, Anna-Marie; McEvoy, Lindsey; Moneta, Lauren; Lubianski, Troy; Coopersmith, Noe; Vigo, Nicholas; Hart, Christopher; Riddle, Artur; Ettinger, Olivia; Nold, Casey; Durham, Heather; MacArthur, Carol; McEvoy, Cynthia; Steyger, Peter S

    2017-06-01

    Hearing loss rates in infants admitted to neonatal intensive care units (NICU) run at 2-15%, compared to 0.3% in full-term births. The etiology of this difference remains poorly understood. We examined whether the level of ambient sound and/or cumulative gentamicin (an aminoglycoside) exposure affect NICU hearing screening results, as either exposure can cause acquired, permanent hearing loss. We hypothesized that higher levels of ambient sound in the NICU, and/or gentamicin dosing, increase the risk of referral on the distortion product otoacoustic emission (DPOAE) assessments and/or automated auditory brainstem response (AABR) screens. This was a prospective pilot outcomes study of 82 infants (sound pressure level dosimeter was used to collect daily sound exposure in the NICU for each neonate. Gentamicin dosing was also calculated for each infant, including the total daily dose based on body mass (mg/kg/day), as well as the total number of treatment days. DPOAE and AABR assessments were conducted prior to discharge to evaluate hearing status. Exclusion criteria included congenital infections associated with hearing loss, and congenital craniofacial or otologic abnormalities. The mean level of ambient sound was 62.9 dBA (range 51.8-70.6 dBA), greatly exceeding American Academy of Pediatrics (AAP) recommendation of 4172 Hz) was 44%. DPOAE referrals were significantly greater for infants receiving >2 days of gentamicin dosing compared to fewer doses (p = 0.004). The effect of sound exposure and gentamicin treatment on hearing could not be determined due to the low number of NICU infants without gentamicin exposure (for control comparisons). All infants were exposed to higher levels of ambient sound that substantially exceed AAP guidelines. More referrals were generated by DPOAE assessments than with AABR screens, with significantly more DPOAE referrals with a high-frequency F2 range, consistent with sound- and/or gentamicin-induced cochlear dysfunction. Adding

  8. Early In Vitro and In Vivo Development of High-Level Daptomycin Resistance Is Common in Mitis Group Streptococci after Exposure to Daptomycin

    Science.gov (United States)

    García-de-la-Mària, Cristina; Pericas, Juan M.; del Río, Ana; Castañeda, Ximena; Vila-Farrés, Xavier; Armero, Yolanda; Espinal, Paula A.; Cervera, Carlos; Soy, Dolors; Falces, Carlos; Ninot, Salvador; Almela, Manel; Mestres, Carlos A.; Gatell, Jose M.; Vila, Jordi; Moreno, Asuncion; Marco, Francesc

    2013-01-01

    The development of high-level daptomycin resistance (HLDR; MIC of ≥256 mg/liter) after exposure to daptomycin has recently been reported in viridans group streptococcus (VGS) isolates. Our study objectives were as follows: to know whether in vitro development of HLDR after exposure to daptomycin was common among clinical isolates of VGS and Streptococcus bovis; to determine whether HLDR also developed during the administration of daptomycin to treat experimental endocarditis caused by the daptomycin-susceptible, penicillin-resistant Streptococcus mitis strain S. mitis 351; and to establish whether combination with gentamicin prevented the development of HLDR in vitro and in vivo. In vitro studies were performed with 114 VGS strains (mitis group, 92; anginosus group, 10; mutans group, 8; and salivarius group, 4) and 54 Streptococcus bovis strains isolated from 168 consecutive patients with infective endocarditis diagnosed between 1995 and 2010. HLDR was only observed after 24 h of exposure to daptomycin in 27% of the mitis group, including 27% of S. mitis isolates, 47% of S. oralis isolates, and 13% of S. sanguis isolates. In our experimental model, HLDR was detected in 7/11 (63%) and 8/12 (67%) isolates recovered from vegetations after 48 h of daptomycin administered at 6 mg/kg of body weight/24 h and 10 mg/kg/24 h, respectively. In vitro, time-kill experiments showed that daptomycin plus gentamicin was bactericidal against S. mitis 351 at tested concentrations of 0.5 and 1 times the MIC and prevented the development of HLDR. In vivo, the addition of gentamicin at 1 mg/kg/8 h to both daptomycin arms prevented HLDR in 21 out of 23 (91%) rabbits. Daptomycin plus gentamicin was at least as effective as vancomycin plus gentamicin. In conclusion, HLDR develops rapidly and frequently in vitro and in vivo among mitis group streptococci. Combining daptomycin with gentamicin enhanced its activity and prevented the development of HLDR in most cases. PMID:23478959

  9. Influence of Nonpolar Substances on the Extraction Efficiency of Six Alkaloids in Zoagumhwan Investigated by Ultra Performance Liquid Chromatography and Photodiode Array Detection

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    Shijing Liu

    2012-11-01

    Full Text Available A reverse phase ultra performance liquid chromatography and photodiode array (UPLC-PDA detection method was established for the determination of six alkaloids in Zoagumhwan (ZGW, and further for investigating the influence of nonpolar substances on the extraction efficiency of these alkaloids. The method was based on a BEH C18 (50 mm × 2.1 mm, 1.7 μm column and mobile phase of aqueous phosphoric acid and acetonitrile including 0.05% buffer solution under gradient elution. ZGW samples of ZGW I, II, III and IV were obtained and prepared by pre-processing the crude materials of Coptidis rhizoma and Evodiae fructus using four technologies, namely direct water decoction, removal of nonpolar substances in Evodiae fructus by supercritical fluid extraction (SFE, removal of nonpolar substances in ZGW by SFE and removal of nonpolar substances in ZGW by steam distillation. The developed and validated UPLC-PDA method was precise, accurate and sensitive enough based on the facts that the six alkaloids showed good regression (r > 0.9998, the limit of detections and quantifications for six alkaloids were less than 28.8 and 94.5 ng/mL, respectively, and the recovery was in the range of 98.56%–103.24%. The sequence of the total contents of six alkaloids in these samples was ZGW II > ZGW IV > ZGW III > ZGW I. ZGW II, in which nonpolar substances, including essential oils, were firstly removed from Evodiae fructus by SFE, had the highest content of the total alkaloids, indicating that extraction efficiency of the total alkaloids could be remarkably increased after Evodiae fructus being extracted by SFE.

  10. RESISTANCE PATTERN OF FECAL ESCHERICHIA COLI IN SELECTED BROILER FARMS OF EASTERN HARARGHE ZONE, ETHIOPIA

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    Tesfaheywet Zeryehun

    2013-02-01

    Full Text Available A study was conducted to determine the pattern of antimicrobial resistance in Escherichia coli isolated from Cloacal swab of broiler chickens in selected farms of Eastern Harrarge zone of Ethiopia. Isolation and identification of Escherichia coli were done by using enrichment media, selective media, and biochemical tests.65 selected isolates were subjected to 9 antimicrobial agents to determine their resistance by the disk diffusion method. Accordingly, the resistance of E.coli was tetracycline (90%, streptomycin (78%, ampicillin (60%, amoxicillin (56%, erythromycin (45%, ciprofloxacin (38%, and chloramphenicol (15%. None of the isolates showed resistance to gentamicin. Sensitivity was observed in case of 80%, 77%, 44%, 32%, 26%, 20%, 20%, 15%, and 10% of the isolates for chloramphenicol, gentamicin, ciprofloxacin, amoxicillin, ampicillin, streptomycin, erythromycin, and tetracycline, respectively. Intermediate resistance/susceptibility was recorded for 5-35% of the isolates. 92.3% of the isolates tested showed multidrug resistance for 2 or more antimicrobials and the highest levels (18.5% of multidrug-resistant E. coli were observed for 3 antimicrobials accounting 7.7% for tetracycline-ampicillin-streptomycin and 10.8% for tetracycline-ampicillin-amoxicillin. This study showed resistance against the antibiotics that are commonly used in poultry. Furthermore, it was concluded that gentamicin, chloramphenicole and ciproflaxin will be the first drugs of choice to resist infections caused by E. coli in chicken in Ethiopia. These findings confirm significant increase in the incidence of antimicrobial resistance in the E. coli isolates which is most probably due to increased use of antibiotics asfeed additives for growth promotion and prevention of diseases and use of inappropriate antibiotics for treatment of diseases. Hence, excess or abusive use of antimicrobials should be guarded through judicious application of antimicrobials.

  11. ANTIMICROBIAL RESISTANT PATTERN OF FECAL ESCHERICHIA COLI IN SELECTED BROILER FARMS OF EASTERN HARARGE ZONE, ETHIOPIA

    Directory of Open Access Journals (Sweden)

    Tesfaheywet Zeryehun

    2013-12-01

    Full Text Available A study was conducted to determine the pattern of antimicrobial resistance in Escherichia coli isolated from Cloacal swab of broiler chickens in selected farms of Eastern Harrarge zone of Ethiopia. Isolation and identification of Escherichia coli were done by using enrichment media, selective media, and biochemical tests. 65 selected isolates were subjected to 9 antimicrobial agents to determine their resistance by the disk diffusion method. Accordingly, the resistance of E.coli was tetracycline (90%, streptomycin (78%, ampicillin (60%, amoxicillin (56%, erythromycin (45%, ciprofloxacin (38%, and chloramphenicol (15%. None of the isolates showed resistance to gentamicin. Sensitivity was observed in case of 80%, 77%, 44%, 32%, 26%, 20%, 20%, 15%, and 10% of the isolates for chloramphenicol, gentamicin, ciprofloxacin, amoxicillin, ampicillin, streptomycin, erythromycin, and tetracycline, respectively. Intermediate resistance/susceptibility was recorded for 5-35% of the isolates. 92.3% of the isolates tested showed multidrug resistance for 2 or more antimicrobials and the highest levels (18.5% of multidrug-resistant E. coli were observed for 3 antimicrobials accounting 7.7% for tetracycline-ampicillin-streptomycin and 10.8% for tetracycline-ampicillin-amoxicillin. This study showed resistance against the antibiotics that are commonly used in poultry. Furthermore, it was concluded that gentamicin, chloramphenicole and ciproflaxin will be the first drugs of choice to resist infections caused by E. coli in chicken in Ethiopia. These findings confirm significant increase in the incidence of antimicrobial resistance in the E. coli isolates which is most probably due to increased use of antibiotics as feed additives for growth promotion and prevention of diseases and use of inappropriate