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Sample records for acids survival mechanisms

  1. Mechanism of Human Influenza Virus RNA Persistence and Virion Survival in Feces: Mucus Protects Virions From Acid and Digestive Juices.

    Science.gov (United States)

    Hirose, Ryohei; Nakaya, Takaaki; Naito, Yuji; Daidoji, Tomo; Watanabe, Yohei; Yasuda, Hiroaki; Konishi, Hideyuki; Itoh, Yoshito

    2017-07-01

    Although viral RNA or infectious virions have been detected in the feces of individuals infected with human influenza A and B viruses (IAV/IBV), the mechanism of viral survival in the gastrointestinal tract remains unclear. We developed a model that attempts to recapitulate the conditions encountered by a swallowed virus. While IAV/IBV are vulnerable to simulated digestive juices (gastric acid and bile/pancreatic juice), highly viscous mucus protects viral RNA and virions, allowing the virus to retain its infectivity. Our results suggest that virions and RNA present in swallowed mucus are not inactivated or degraded by the gastrointestinal environment, allowing their detection in feces. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  2. The glutamate decarboxylase acid resistance mechanism affects survival of Listeria monocytogenes LO28 in modified atmosphere-packaged foods.

    Science.gov (United States)

    Francis, G A; Scollard, J; Meally, A; Bolton, D J; Gahan, C G M; Cotter, P D; Hill, C; O'Beirne, D

    2007-12-01

    The contribution of the glutamate decarboxylase (GAD) acid resistance system to survival and growth of Listeria monocytogenes LO28 in modified atmosphere-packaged foods was examined. The survival and growth of the wild-type LO28 and four GAD deletion mutants (DeltagadA, DeltagadB, DeltagadC, DeltagadAB) in packaged foods (minced beef, lettuce, dry coleslaw mix) during storage at 4, 8 and 15 degrees C were studied. Survival and growth patterns varied with strain, product type, gas atmosphere and storage temperature. In minced beef, the wild-type LO28 survived better (P lettuce, gadA played the most important role, while the gadB and gadC genes played the greatest role in packaged coleslaw (at 15 degrees C). This work demonstrates that elements of the GAD system play significant roles in survival of L. monocytogenes LO28 during storage in modified atmosphere-packaged foods. A better understanding of how L. monocytogenes behaves in modified atmosphere-packaged foods, and how it responds to elevated carbon dioxide atmospheres.

  3. Surviving a Dry Future: Abscisic Acid (ABA-Mediated Plant Mechanisms for Conserving Water under Low Humidity

    Directory of Open Access Journals (Sweden)

    Frances C. Sussmilch

    2017-11-01

    Full Text Available Angiosperms are able to respond rapidly to the first sign of dry conditions, a decrease in air humidity, more accurately described as an increase in the vapor pressure deficit between the leaf and the atmosphere (VPD, by abscisic acid (ABA-mediated stomatal closure. The genes underlying this response offer valuable candidates for targeted selection of crop varieties with improved drought tolerance, a critical goal for current plant breeding programs, to maximize crop production in drier and increasingly marginalized environments, and meet the demands of a growing population in the face of a changing climate. Here, we review current understanding of the genetic mechanisms underpinning ABA-mediated stomatal closure, a key means for conserving water under dry conditions, examine how these mechanisms evolved, and discuss what remains to be investigated.

  4. Survival of Helicobacter pylori in gastric acidic territory.

    Science.gov (United States)

    Ansari, Shamshul; Yamaoka, Yoshio

    2017-08-01

    Helicobacter pylori is well adapted to colonize the epithelial surface of the human gastric mucosa and can cause persistent infections. In order to infect the gastric mucosa, it has to survive in the gastric acidic pH. This organism has well developed mechanisms to neutralize the effects of acidic pH. This review article was designed to summarize the various functional and molecular aspects by which the bacterium can combat and survive the gastric acidic pH in order to establish the persistent infections. We used the keywords (acid acclimation, gastric acidic environment, H. pylori and survival) in combination or alone for pubmed search of recent scientific literatures. One hundred and forty one papers published between 1989 and 2016 were sorted out. The articles published with only abstracts, other than in English language, case reports and reviews were excluded. Many literatures describing the role of several factors in acid survival were found. Recently, the role of several other factors has been claimed to participate in acid survival. In conclusion, this organism has well characterized mechanisms for acid survival. © 2017 John Wiley & Sons Ltd.

  5. Dinosaur Peptides Suggest Mechanisms of Protein Survival

    Energy Technology Data Exchange (ETDEWEB)

    San Antonio, James D.; Schweitzer, Mary H.; Jensen, Shane T.; Kalluri, Raghu; Buckley, Michael; Orgel, Joseph P.R.O. (Harvard-Med); (IIT); (NCSU); (UPENN); (Manchester); (Orthovita)

    2011-09-16

    Eleven collagen peptide sequences recovered from chemical extracts of dinosaur bones were mapped onto molecular models of the vertebrate collagen fibril derived from extant taxa. The dinosaur peptides localized to fibril regions protected by the close packing of collagen molecules, and contained few acidic amino acids. Four peptides mapped to collagen regions crucial for cell-collagen interactions and tissue development. Dinosaur peptides were not represented in more exposed parts of the collagen fibril or regions mediating intermolecular cross-linking. Thus functionally significant regions of collagen fibrils that are physically shielded within the fibril may be preferentially preserved in fossils. These results show empirically that structure-function relationships at the molecular level could contribute to selective preservation in fossilized vertebrate remains across geological time, suggest a 'preservation motif', and bolster current concepts linking collagen structure to biological function. This non-random distribution supports the hypothesis that the peptides are produced by the extinct organisms and suggests a chemical mechanism for survival.

  6. Dinosaur peptides suggest mechanisms of protein survival.

    Directory of Open Access Journals (Sweden)

    James D San Antonio

    Full Text Available Eleven collagen peptide sequences recovered from chemical extracts of dinosaur bones were mapped onto molecular models of the vertebrate collagen fibril derived from extant taxa. The dinosaur peptides localized to fibril regions protected by the close packing of collagen molecules, and contained few acidic amino acids. Four peptides mapped to collagen regions crucial for cell-collagen interactions and tissue development. Dinosaur peptides were not represented in more exposed parts of the collagen fibril or regions mediating intermolecular cross-linking. Thus functionally significant regions of collagen fibrils that are physically shielded within the fibril may be preferentially preserved in fossils. These results show empirically that structure-function relationships at the molecular level could contribute to selective preservation in fossilized vertebrate remains across geological time, suggest a 'preservation motif', and bolster current concepts linking collagen structure to biological function. This non-random distribution supports the hypothesis that the peptides are produced by the extinct organisms and suggests a chemical mechanism for survival.

  7. Uric acid, an important antioxidant contributing to survival in termites

    Science.gov (United States)

    Tasaki, Eisuke; Sakurai, Hiroki; Nitao, Masaru; Matsuura, Kenji; Iuchi, Yoshihito

    2017-01-01

    Reactive oxygen species (ROS) are generated spontaneously in all organisms and cause oxidative damage to biomolecules when present in excess. Accumulated oxidative damage accelerates aging; enhanced antioxidant capacity may be a positive factor for longevity. Recently, numerous studies of aging and longevity have been performed using short-lived animals, however, longevity mechanisms remain unknown. Here we show that a termite Reticulitermes speratus that is thought to be long-lived eusocial insect than other solitary insects uses large quantities of uric acid as an antioxidant against ROS. We demonstrated that the accumulation of uric acid considerably increases the free radical-scavenging activity and resistance against ultraviolet-induced oxidative stress in laboratory-maintained termites. In addition, we found that externally administered uric acid aided termite survival under highly oxidative conditions. The present data demonstrates that in addition to nutritional and metabolic roles, uric acid is an essential antioxidant for survival and contributes significantly to longevity. Uric acid also plays important roles in primates but causes gout when present in excess in humans. Further longevity studies of long-lived organisms may provide important breakthroughs with human health applications. PMID:28609463

  8. Acid tolerance response and survival by oral bacteria.

    Science.gov (United States)

    Svensäter, G; Larsson, U B; Greif, E C; Cvitkovitch, D G; Hamilton, I R

    1997-10-01

    Using 21 species of oral bacteria, representing six acidogenic genera, we undertook to determine whether the pH-limiting exponential growth is related to the ability of the organisms to generate an acid-tolerance response that results in enhanced survival at low pH. The lower pH limit of exponential growth varied by more than two units with that of Neisseria A182 at pH 6.34; growth of Lactobacillus casei RB1014 stopped at pH 3.81, with species of Actinomyces, Enterococcus, Prevotella and Streptococcus falling between these limits. The working hypothesis was that the organisms with the higher pH limits for growth are unable to respond to acidic environments in order to survive, whereas the more aciduric organisms would possess or acquire acid tolerance. Adaptation to acid tolerance was tested by determining whether the prior exposure of exponential-phase cells to a low, sub-lethal pH would trigger the induction of a mechanism that would enhance survival at a pH killing pH 7.5 control cells. The killing pH varied from pH 4.5 for Prevotella intermedia ATCC 25611 to pH 2.3 for the three Lactobacillus casei strains in the study, with the three Streptococcus mutans strains killed at pH 3.0 for 3 h. The adaptation experiments revealed three groups of organisms: non-acid-responders, generally representing strains with the highest terminal pH values; weak acid-responders in the middle of the pH list, generating low numbers of survivors at one or two pH values, and the aciduric, strong responders generating a high number of survivors at pH values in the range 6.0 to 3.5, but not at pH 7.5. Predominant among the latter group were the S. mutans and Lactobacilli casei strains, with the most significant adaptive response exhibited by S. mutans LT11 and S. mutans Ingbritt, involving a process that required protein synthesis. Time course experiments with the latter organisms indicated that 90-120 min was required after exposure to the triggering pH before the acid response was

  9. MECHANICAL TRANSMISSION AND SURVIVAL OF BACTERIAL ...

    African Journals Online (AJOL)

    jen

    Key Words: Bacterial wilt, enset, survival, transmission, Xanthomonas campestris pv. musacearum. RÉSUMÉ. La transmission .... than young plants. A 100% disease incidence was recorded at 60 days after inoculation on plants inoculated at 6 months after transplanting. Plants inoculated at. 6 months after transplanting had ...

  10. SURVIVABILITY THROUGH OPTIMIZING RESILIENT MECHANISMS (STORM)

    Science.gov (United States)

    2017-04-01

    increases CSP’s revenue and helps lowering the price . This eventually creates a virtuous cycle, which will benefit both the CSP and legitimate...prevention, detection, survivability and recovery. It follows that in security- conscious organizations, the cyber security investment portfolio is

  11. Neuronal survival in the brain: neuron type-specific mechanisms

    DEFF Research Database (Denmark)

    Pfisterer, Ulrich Gottfried; Khodosevich, Konstantin

    2017-01-01

    Neurogenic regions of mammalian brain produce many more neurons that will eventually survive and reach a mature stage. Developmental cell death affects both embryonically produced immature neurons and those immature neurons that are generated in regions of adult neurogenesis. Removal of substantial...... for survival in a certain brain region. This review focuses on how immature neurons survive during normal and impaired brain development, both in the embryonic/neonatal brain and in brain regions associated with adult neurogenesis, and emphasizes neuron type-specific mechanisms that help to survive for various...

  12. The Survival Advantage: Underlying Mechanisms and Extant Limitations

    Directory of Open Access Journals (Sweden)

    Stephanie A. Kazanas

    2015-04-01

    Full Text Available Recently, researchers have begun to investigate the function of memory in our evolutionary history. According to Nairne and colleagues (e.g., Nairne, Pandeirada, and Thompson, 2008; Nairne, Thompson, and Pandeirada, 2007, the best mnemonic strategy for learning lists of unrelated words may be one that addresses the same problems that our Pleistocene ancestors faced: fitness-relevant problems including securing food and water, as well as protecting themselves from predators. Survival processing has been shown to promote better recall and recognition memory than many well-known mnemonic strategies (e.g., pleasantness ratings, imagery, generation, etc.. However, the survival advantage does not extend to all types of stimuli and tasks. The current review presents research that has replicated Nairne et al.'s (2007 original findings, in addition to the research designs that fail to replicate the survival advantage. In other words, there are specific manipulations in which survival processing does not appear to benefit memory any more than other strategies. Potential mechanisms for the survival advantage are described, with an emphasis on those that are the most plausible. These proximate mechanisms outline the memory processes that may contribute to the advantage, although the ultimate mechanism may be the congruity between the survival scenario and Pleistocene problem-solving.

  13. Noisy Response to Antibiotic Stress Predicts Subsequent Single-Cell Survival in an Acidic Environment.

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    Mitosch, Karin; Rieckh, Georg; Bollenbach, Tobias

    2017-04-26

    Antibiotics elicit drastic changes in microbial gene expression, including the induction of stress response genes. While certain stress responses are known to "cross-protect" bacteria from other stressors, it is unclear whether cellular responses to antibiotics have a similar protective role. By measuring the genome-wide transcriptional response dynamics of Escherichia coli to four antibiotics, we found that trimethoprim induces a rapid acid stress response that protects bacteria from subsequent exposure to acid. Combining microfluidics with time-lapse imaging to monitor survival and acid stress response in single cells revealed that the noisy expression of the acid resistance operon gadBC correlates with single-cell survival. Cells with higher gadBC expression following trimethoprim maintain higher intracellular pH and survive the acid stress longer. The seemingly random single-cell survival under acid stress can therefore be predicted from gadBC expression and rationalized in terms of GadB/C molecular function. Overall, we provide a roadmap for identifying the molecular mechanisms of single-cell cross-protection between antibiotics and other stressors. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  14. Survival of probiotic lactobacilli in acidic environments is enhanced in the presence of metabolizable sugars.

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    Corcoran, B M; Stanton, C; Fitzgerald, G F; Ross, R P

    2005-06-01

    Lactobacillus rhamnosus GG is an industrially significant probiotic strain with proven health benefits. In this study, the effect of glucose on L. rhamnosus GG survival was analyzed in simulated gastric juice at pH 2.0. It was found that the presence of 19.4 mM glucose resulted in up to 6-log10-enhanced survival following 90 min of exposure. Further work with dilute HCl confirmed that glucose was the sole component responsible. Comparative analysis with other Lactobacillus strains revealed that enhanced survival was apparent in all strains, but at different pH values. The presence of glucose at concentrations from 1 to 19.4 mM enhanced L. rhamnosus GG survival from 6.4 to 8 log10 CFU ml(-1) in simulated gastric juice. The mechanisms behind the protective effect of glucose were investigated. Addition of N',N'-dicyclohexylcarbodiimide to simulated gastric juice caused survival to collapse, which was indicative of a prominent role in inhibition of F0F1-ATPase. Further work with neomycin-resistant mutants that exhibited 38% to 48% of the F0F1-ATPase activity of the parent confirmed this, as the survival in the presence of glucose of these mutants decreased 3 x 10(6)-fold compared with the survival of the wild type (which had a viability of 8.02 log10 CFU ml(-1)). L. rhamnosus GG survival in acidic conditions occurred only in the presence of sugars that it could metabolize efficiently. To confirm the involvement of glycolysis in the glucose effect, iodoacetic acid was used to inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity. The reduction in GAPDH activity caused survival to decrease by 8.30 log10 CFU ml(-1) in the presence of glucose. The data indicate that glucose provides ATP to F0F1-ATPase via glycolysis, enabling proton exclusion and thereby enhancing survival during gastric transit.

  15. Stress-Survival Gene Identification From an Acid Mine Drainage Algal Mat Community

    Science.gov (United States)

    Urbina-Navarrete, J.; Fujishima, K.; Paulino-Lima, I. G.; Rothschild-Mancinelli, B.; Rothschild, L. J.

    2014-12-01

    Microbial communities from acid mine drainage environments are exposed to multiple stressors to include low pH, high dissolved metal loads, seasonal freezing, and desiccation. The microbial and algal communities that inhabit these niche environments have evolved strategies that allow for their ecological success. Metagenomic analyses are useful in identifying species diversity, however they do not elucidate the mechanisms that allow for the resilience of a community under these extreme conditions. Many known or predicted genes encode for protein products that are unknown, or similarly, many proteins cannot be traced to their gene of origin. This investigation seeks to identify genes that are active in an algal consortium during stress from living in an acid mine drainage environment. Our approach involves using the entire community transcriptome for a functional screen in an Escherichia coli host. This approach directly targets the genes involved in survival, without need for characterizing the members of the consortium.The consortium was harvested and stressed with conditions similar to the native environment it was collected from. Exposure to low pH (E. coli. The transformed E. coli were exposed to the same stressors as the original algal consortium to select for surviving cells. Successful cells incorporated the transcripts that encode survival mechanisms, thus allowing for selection and identification of the gene(s) involved. Initial selection screens for freeze and desiccation tolerance have yielded E. coli that are 1 order of magnitude more resistant to freezing (0.01% survival of control with no transcript, 0.2% survival of E. coli with transcript) and 3 orders of magnitude more resistant to desiccation (0.005% survival of control cells with no transcripts, 5% survival of cells with transcript).This work is transformative because genetic functions can be selected without having prior knowledge of the genes or of the organisms involved. Work continues to

  16. Antioxidant supplementation can reduce the survival costs of excess amino acid intake in honeybees.

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    Archer, C Ruth; Köhler, Angela; Pirk, Christian W W; Oosthuizen, Vinette; Apostolides, Zeno; Nicolson, Susan W

    2014-12-01

    Over-consuming amino acids is associated with reduced survival in many species, including honeybees. The mechanisms responsible for this are unclear but one possibility is that excessive intake of amino acids increases oxidative damage. If this is the case, antioxidant supplementation may help reduce the survival costs of high amino acid intake. We tested this hypothesis in African honeybees (Apis mellifera scutellata) using the major antioxidant in green tea, epigallocatechin-3-gallate (EGCG). We first determined the dose-range of EGCG that improved survival of caged honeybees fed sucrose solution. We then provided bees with eight diets that differed in their ratio of essential amino acids (EAA) to carbohydrate (C) (0:1, 1:250, 1:100, 1:75, 1:50, 1:25, 1:10, 1:5 EAA:C) and also in their EGCG dose (0.0 or 0.4 mM). We found that bees fed sucrose only solution survived better than bees fed EAA diets. Despite this, bees preferred a diet that contained intermediate ratios of EAA:C (ca. 1:25), which may represent the high demands for nitrogen of developing nurse bees. EGCG supplementation improved honeybee survival but only at an intermediate dose (0.3-0.5 mM) and in bees fed low EAA diets (1:250, 1:100 EAA:C). That EGCG counteracted the lifespan reducing effects of eating low EAA diets suggests that oxidative damage may be involved in the association between EAAs and lifespan in honeybees. However, that EGCG had no effect on survival in bees fed high EAA diets suggests that there are other physiological costs of over-consuming EAAs in honeybees. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Interactive effects involving different classes of excitatory amino acid receptors and the survival of cerebellar granule cells in culture

    DEFF Research Database (Denmark)

    Balázs, R; Hack, N; Jørgensen, Ole Steen

    1990-01-01

    Differentiating granule cells develop survival requirements in culture which can be met by treatment with high K+ or N-methyl-D-aspartate (NMDA) and, according to our recent findings, also with low concentrations of kainic acid (KA, 50 microM). We have now attempted to elucidate the mechanism(s) ...

  18. Overview on mechanisms of acetic acid resistance in acetic acid bacteria.

    Science.gov (United States)

    Wang, Bin; Shao, Yanchun; Chen, Fusheng

    2015-02-01

    Acetic acid bacteria (AAB) are a group of gram-negative or gram-variable bacteria which possess an obligate aerobic property with oxygen as the terminal electron acceptor, meanwhile transform ethanol and sugar to corresponding aldehydes, ketones and organic acids. Since the first genus Acetobacter of AAB was established in 1898, 16 AAB genera have been recorded so far. As the main producer of a world-wide condiment, vinegar, AAB have evolved an elegant adaptive system that enables them to survive and produce a high concentration of acetic acid. Some researches and reviews focused on mechanisms of acid resistance in enteric bacteria and made the mechanisms thoroughly understood, while a few investigations did in AAB. As the related technologies with proteome, transcriptome and genome were rapidly developed and applied to AAB research, some plausible mechanisms conferring acetic acid resistance in some AAB strains have been published. In this review, the related mechanisms of AAB against acetic acid with acetic acid assimilation, transportation systems, cell morphology and membrane compositions, adaptation response, and fermentation conditions will be described. Finally, a framework for future research for anti-acid AAB will be provided.

  19. Survival Predictions of Ceramic Crowns Using Statistical Fracture Mechanics.

    Science.gov (United States)

    Nasrin, S; Katsube, N; Seghi, R R; Rokhlin, S I

    2017-05-01

    This work establishes a survival probability methodology for interface-initiated fatigue failures of monolithic ceramic crowns under simulated masticatory loading. A complete 3-dimensional (3D) finite element analysis model of a minimally reduced molar crown was developed using commercially available hardware and software. Estimates of material surface flaw distributions and fatigue parameters for 3 reinforced glass-ceramics (fluormica [FM], leucite [LR], and lithium disilicate [LD]) and a dense sintered yttrium-stabilized zirconia (YZ) were obtained from the literature and incorporated into the model. Utilizing the proposed fracture mechanics-based model, crown survival probability as a function of loading cycles was obtained from simulations performed on the 4 ceramic materials utilizing identical crown geometries and loading conditions. The weaker ceramic materials (FM and LR) resulted in lower survival rates than the more recently developed higher-strength ceramic materials (LD and YZ). The simulated 10-y survival rate of crowns fabricated from YZ was only slightly better than those fabricated from LD. In addition, 2 of the model crown systems (FM and LD) were expanded to determine regional-dependent failure probabilities. This analysis predicted that the LD-based crowns were more likely to fail from fractures initiating from margin areas, whereas the FM-based crowns showed a slightly higher probability of failure from fractures initiating from the occlusal table below the contact areas. These 2 predicted fracture initiation locations have some agreement with reported fractographic analyses of failed crowns. In this model, we considered the maximum tensile stress tangential to the interfacial surface, as opposed to the more universally reported maximum principal stress, because it more directly impacts crack propagation. While the accuracy of these predictions needs to be experimentally verified, the model can provide a fundamental understanding of the

  20. Political Mechanisms for Long-Range Survival and Development

    Science.gov (United States)

    Marshall, W.

    As the first species aware of extinction and capable of proactively ensuring our long-term survival and development, it is striking that we do not do so with the rigor, formality, and foresight it requires. Only from a reactive posture have we responded to the challenges of global warfare, human rights, environmental concerns, and sustainable development. Despite our awareness of the possibility for extinction and apocalyptic set-backs to our evolution, and despite the existence of long-range studies-which must still be dramatically increased-proactive global policy implementation regarding our long-term survival and development is arguably non-existent. This lack of long-term policy making can be attributed in part to the lack of formal political mechanisms to facilitate longer-range policy making that extends 30 years or more into the future. Political mechanisms for infusing long-range thinking, research, and strategic planning into the policy-making process can help correct this shortcoming and provide the motivation needed to adequately address long-term challenges with the political rigor required to effectively establish and implement long-term policies. There are some efforts that attempt to address longer-range issues, but those efforts often do not connect to the political process, do not extend 30 or more years into the future, are not well-funded, and are not sufficiently systemic. Political mechanisms for long-range survival and prosperity could correct these inadequacies by raising awareness, providing funding, and most importantly, leveraging political rigor to establish and enforce long-range strategic planning and policies. The feasibility of such mechanisms should first be rigorously studied and assessed in a feasibility study, which could then inform implementation. This paper will present the case for such a study and suggest some possible political mechanisms that should be investigated further in the proposed study. This work is being further

  1. A Mycobacterium avium subsp. paratuberculosis predicted serine protease is associated with acid stress and intraphagosomal survival

    Directory of Open Access Journals (Sweden)

    Abirami Kugadas

    2016-08-01

    Full Text Available AbstractThe ability to maintain intra-cellular pH is crucial for bacteria and other microbes to survive in diverse environments, particularly those that undergo fluctuations in pH. Mechanisms of acid resistance remain poorly understood in mycobacteria. Although studies investigating acid stress in M. tuberculosis are gaining traction, few center on Mycobacterium avium subsp. paratuberculosis (MAP, the etiological agent of chronic enteritis in ruminants. We identified a MAP acid stress response network involved in macrophage infection. The central node of this network was MAP0403, a predicted serine protease that shared an 86% amino acid identity with MarP in M. tuberculosis. Previous studies confirmed MarP as a serine protease integral to maintaining intra-bacterial pH and survival in acid in vitro and in vivo. We show that MAP0403 is upregulated in infected macrophage and MAC-T cells and coincided with phagosome acidification. Treatment of mammalian cells with bafilomcyin A1, a potent inhibitor of phagosomal vATPases, diminished MAP0403 transcription. MAP0403 expression was also noted in acidic medium. A surrogate host, M. smegmatis mc2 155, was designed to express MAP0403 and when exposed to either macrophages or in vitro acid stress had increase bacterial cell viability, which corresponds to maintenance of intra-bacterial pH in acidic (pH = 5 conditions. These data suggest that MAP0403 may be the equivalent of MarP in MAP. Future studies confirming MAP0403 as a serine protease and exploring its structure and possible substrates are warranted.

  2. Mechanisms and improvement of acid resistance in lactic acid bacteria.

    Science.gov (United States)

    Wang, Chao; Cui, Yanhua; Qu, Xiaojun

    2018-03-01

    Lactic acid bacteria (LAB) can take advantage of fermentable carbohydrates to produce lactic acid. They are proverbially applied in industry, agricultural production, animal husbandry, food enterprise, pharmaceutical engineering and some other important fields, which are closely related to human life. For performing the probiotic functions, LAB have to face the low pH environment of the gastrointestinal tract. Therefore, acid resistance of LAB is of great importance not only for their own growth, but also for fermentation and preparation of probiotic products. Recent research studies on acid resistance mechanisms of LAB are mainly focused on neutralization process, biofilm and cell density, proton pump, protection of macromolecules, pre-adaptation and cross-protection, and effect of solutes. In this context, biotechnological strategies such as synthetic biology, genome shuffling, high pressure homogenization and adaptive laboratory evolution were also used to improve the acid resistance of LAB to respond to constantly changing low pH environment.

  3. The Role of Amino Acid Permeases and Tryptophan Biosynthesis in Cryptococcus neoformans Survival

    Science.gov (United States)

    Fernandes, João Daniel Santos; Martho, Kevin; Tofik, Veridiana; Vallim, Marcelo A.; Pascon, Renata C.

    2015-01-01

    Metabolic diversity is an important factor during microbial adaptation to different environments. Among metabolic processes, amino acid biosynthesis has been demonstrated to be relevant for survival for many microbial pathogens, whereas the association between pathogenesis and amino acid uptake and recycling are less well-established. Cryptococcus neoformans is an opportunistic fungal pathogen with many habitats. As a result, it faces frequent metabolic shifts and challenges during its life cycle. Here we studied the C. neoformans tryptophan biosynthetic pathway and found that the pathway is essential. RNAi indicated that interruptions in the biosynthetic pathway render strains inviable. However, auxotroph complementation can be partially achieved by tryptophan uptake when a non preferred nitrogen source and lower growth temperature are applied, suggesting that amino acid permeases may be the target of nitrogen catabolism repression (NCR). We used bioinformatics to search for amino acid permeases in the C. neoformans and found eight potential global permeases (AAP1 to AAP8). The transcriptional profile of them revealed that they are subjected to regulatory mechanisms which are known to respond to nutritional status in other fungi, such as (i) quality of nitrogen (Nitrogen Catabolism Repression, NCR) and carbon sources (Carbon Catabolism Repression, CCR), (ii) amino acid availability in the extracellular environment (SPS-sensing) and (iii) nutritional deprivation (Global Amino Acid Control, GAAC). This study shows that C. neoformans has fewer amino acid permeases than other model yeasts, and that these proteins may be subjected to complex regulatory mechanisms. Our data suggest that the C. neoformans tryptophan biosynthetic pathway is an excellent pharmacological target. Furthermore, inhibitors of this pathway cause Cryptococcus growth arrest in vitro. PMID:26162077

  4. The Role of Amino Acid Permeases and Tryptophan Biosynthesis in Cryptococcus neoformans Survival.

    Directory of Open Access Journals (Sweden)

    João Daniel Santos Fernandes

    Full Text Available Metabolic diversity is an important factor during microbial adaptation to different environments. Among metabolic processes, amino acid biosynthesis has been demonstrated to be relevant for survival for many microbial pathogens, whereas the association between pathogenesis and amino acid uptake and recycling are less well-established. Cryptococcus neoformans is an opportunistic fungal pathogen with many habitats. As a result, it faces frequent metabolic shifts and challenges during its life cycle. Here we studied the C. neoformans tryptophan biosynthetic pathway and found that the pathway is essential. RNAi indicated that interruptions in the biosynthetic pathway render strains inviable. However, auxotroph complementation can be partially achieved by tryptophan uptake when a non preferred nitrogen source and lower growth temperature are applied, suggesting that amino acid permeases may be the target of nitrogen catabolism repression (NCR. We used bioinformatics to search for amino acid permeases in the C. neoformans and found eight potential global permeases (AAP1 to AAP8. The transcriptional profile of them revealed that they are subjected to regulatory mechanisms which are known to respond to nutritional status in other fungi, such as (i quality of nitrogen (Nitrogen Catabolism Repression, NCR and carbon sources (Carbon Catabolism Repression, CCR, (ii amino acid availability in the extracellular environment (SPS-sensing and (iii nutritional deprivation (Global Amino Acid Control, GAAC. This study shows that C. neoformans has fewer amino acid permeases than other model yeasts, and that these proteins may be subjected to complex regulatory mechanisms. Our data suggest that the C. neoformans tryptophan biosynthetic pathway is an excellent pharmacological target. Furthermore, inhibitors of this pathway cause Cryptococcus growth arrest in vitro.

  5. Extended survival of several organisms and amino acids under simulated martian surface conditions

    Science.gov (United States)

    Johnson, A. P.; Pratt, L. M.; Vishnivetskaya, T.; Pfiffner, S.; Bryan, R. A.; Dadachova, E.; Whyte, L.; Radtke, K.; Chan, E.; Tronick, S.; Borgonie, G.; Mancinelli, R. L.; Rothschild, L. J.; Rogoff, D. A.; Horikawa, D. D.; Onstott, T. C.

    2011-02-01

    Recent orbital and landed missions have provided substantial evidence for ancient liquid water on the martian surface as well as evidence of more recent sedimentary deposits formed by water and/or ice. These observations raise serious questions regarding an independent origin and evolution of life on Mars. Future missions seek to identify signs of extinct martian biota in the form of biomarkers or morphological characteristics, but the inherent danger of spacecraft-borne terrestrial life makes the possibility of forward contamination a serious threat not only to the life detection experiments, but also to any extant martian ecosystem. A variety of cold and desiccation-tolerant organisms were exposed to 40 days of simulated martian surface conditions while embedded within several centimeters of regolith simulant in order to ascertain the plausibility of such organisms' survival as a function of environmental parameters and burial depth. Relevant amino acid biomarkers associated with terrestrial life were also analyzed in order to understand the feasibility of detecting chemical evidence for previous biological activity. Results indicate that stresses due to desiccation and oxidation were the primary deterrent to organism survival, and that the effects of UV-associated damage, diurnal temperature variations, and reactive atmospheric species were minimal. Organisms with resistance to desiccation and radiation environments showed increased levels of survival after the experiment compared to organisms characterized as psychrotolerant. Amino acid analysis indicated the presence of an oxidation mechanism that migrated downward through the samples during the course of the experiment and likely represents the formation of various oxidizing species at mineral surfaces as water vapor diffused through the regolith. Current sterilization protocols may specifically select for organisms best adapted to survival at the martian surface, namely species that show tolerance to radical

  6. Survival and resuscitation of ten strains of Campylobacter jejuni and Campylobacter coli under acid conditions

    NARCIS (Netherlands)

    Chaveerach, P.; Huurne, ter A.A.H.M.; Lipman, L.J.A.; Knapen, van F.

    2003-01-01

    The culturability of 10 strains of Campylobacter jejuni and Campylobacter coli was studied after the bacteria were exposed to acid conditions for various periods of time. Campylobacter cells could not survive 2 h under acid conditions (formic acid at pH 4). The 10 Campylobacter strains could not be

  7. High serum uric acid concentration predicts poor survival in patients with breast cancer.

    Science.gov (United States)

    Yue, Cai-Feng; Feng, Pin-Ning; Yao, Zhen-Rong; Yu, Xue-Gao; Lin, Wen-Bin; Qian, Yuan-Min; Guo, Yun-Miao; Li, Lai-Sheng; Liu, Min

    2017-10-01

    Uric acid is a product of purine metabolism. Recently, uric acid has gained much attraction in cancer. In this study, we aim to investigate the clinicopathological and prognostic significance of serum uric acid concentration in breast cancer patients. A total of 443 female patients with histopathologically diagnosed breast cancer were included. After a mean follow-up time of 56months, survival was analysed using the Kaplan-Meier method. To further evaluate the prognostic significance of uric acid concentrations, univariate and multivariate Cox regression analyses were applied. Of the clinicopathological parameters, uric acid concentration was associated with age, body mass index, ER status and PR status. Univariate analysis identified that patients with increased uric acid concentration had a significantly inferior overall survival (HR 2.13, 95% CI 1.15-3.94, p=0.016). In multivariate analysis, we found that high uric acid concentration is an independent prognostic factor predicting death, but insufficient to predict local relapse or distant metastasis. Kaplan-Meier analysis indicated that high uric acid concentration is related to the poor overall survival (p=0.013). High uric acid concentration predicts poor survival in patients with breast cancer, and might serve as a potential marker for appropriate management of breast cancer patients. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Mechanical transmission and survival of bacterial wilt on enset ...

    African Journals Online (AJOL)

    The transmission of enset bacterial wilt with contaminated knives and the survival of the causal agent in soil and enset plant debris was studied at the Awassa Agricultural Research Center, Awassa, Ethiopia. Contaminated knives were found to transmit the pathogen from infected to healthy plants. Disease symptoms were ...

  9. Interactive effects involving different classes of excitatory amino acid receptors and the survival of cerebellar granule cells in culture

    DEFF Research Database (Denmark)

    Balázs, R; Hack, N; Jørgensen, Ole Steen

    1990-01-01

    (s) underlying the trophic effect of KA. KA rescue of cells was completely suppressed by blockers of voltage-sensitive calcium channels, such as nifedipine in low concentrations (5 x 10(-7) M), indicating that the promotion of cell survival is mediated through the activation of these channels by membrane...... depolarization. Thus the trophic influences of KA and NMDA share a common mechanism, increased Ca2+ influx (albeit through different routes), a conclusion that is supported by the observation that the effects of these agonists at concentrations causing maximal promotion of cell survival were not additive...... on their own failed to promote, but rather reduced cell survival. The potentiation of the KA effect by the competitive NMDA antagonist APV was counteracted by the weak NMDA agonist, quinolinic acid. These observations suggest that KA alone has both trophic and toxic effects, the latter being mediated...

  10. Influence of membrane fatty acid composition and fluidity on airborne survival of Escherichia coli.

    Science.gov (United States)

    Ng, Tsz Wai; Chan, Wing Lam; Lai, Ka Man

    2018-04-01

    Finding ways to predict and control the survival of bacterial aerosols can contribute to the development of ways to alleviate a number of crucial microbiological problems. Significant damage in the membrane integrity of Escherichia coli during aerosolization and airborne suspension has been revealed which has prompted the question of how the membrane fatty acid composition and fluidity influence the survival of airborne bacteria. Two approaches of using isogenic mutants and different growth temperatures were selected to manipulate the membrane fatty acid composition of E. coli before challenging the bacteria with different relative humidity (RH) levels in an aerosol chamber. Among the mutants (fabR - , cfa. fadA - ), fabR - had the lowest membrane fluidity index (FI) and generally showed a higher survival than the parental strain. Surprisingly, its resistance to airborne stress was so strong that its viability was fully maintained even after airborne suspension at 40% RH, a harsh RH level to bacterial survival. Moreover, E. coli cultured at 20 °C with a higher FI than that at 30 and 37 °C generally had a lower survival after aerosolization and airborne suspension. Unlike FI, individual fatty acid and cyclopropane fatty acid composition did not relate to the bacterial survival. Lipid peroxidation of the membrane was undetected in all the bacteria. Membrane fluidity plays a stronger role in determining the bacteria survival during airborne suspension than during aerosolization. Certain relationships between FI and bacteria survival were identified, which could help predict the transmission of bacteria under different conditions.

  11. Survival and Growth of Probiotic Lactic Acid Bacteria in Refrigerated Pickle Products.

    Science.gov (United States)

    Fan, Sicun; Breidt, Fred; Price, Robert; Pérez-Díaz, Ilenys

    2017-01-01

    We examined 10 lactic acid bacteria that have been previously characterized for commercial use as probiotic cultures, mostly for dairy products, including 1 Pediococcus and 9 Lactobacilli. Our objectives were to develop a rapid procedure for determining the long-term survivability of these cultures in acidified vegetable products and to identify suitable cultures for probiotic brined vegetable products. We therefore developed assays to measure acid resistance of these cultures to lactic and acetic acids, which are present in pickled vegetable products. We used relatively high acid concentrations (compared to commercial products) of 360 mM lactic acid and 420 mM acetic acid to determine acid resistance with a 1 h treatment. Growth rates were measured in a cucumber juice medium at pH 5.3, 4.2, and 3.8, at 30 °C and 0% to 2% NaCl. Significant differences in acid resistance and growth rates were found among the 10 cultures. In general, the acid resistant strains had slower growth rates than the acid sensitive strains. Based on the acid resistance data, selected cultures were tested for long-term survival in a simulated acidified refrigerated cucumber product. We found that one of the most acid resistant strains (Lactobacillus casei) could survive for up to 63 d at 4 °C without significant loss of viability at 10 8 CFU/mL. These data may aid in the development of commercial probiotic refrigerated pickle products. © 2016 Institute of Food Technologists®.

  12. Survival under stress: molecular mechanisms of metabolic rate ...

    African Journals Online (AJOL)

    Studies in my laboratory are analysing the molecular mechanisms and regulatory events that underlie transitions to and from hypometabolic states In systems including anoxia-tolerant turtles and molluscs, estivating snails and toads, hibernating small mammals, and freeze tolerant frogs and insects. Our newest research ...

  13. Dietary antiaging phytochemicals and mechanisms associated with prolonged survival

    Science.gov (United States)

    Si, Hongwei; Liu, Dongmin

    2014-01-01

    Aging is well-known an inevitable process that is influenced by genetic, lifestyle and environmental factors. However, the exact mechanisms underlying the aging process are not well understood. Increasing evidence shows that aging is highly associated with chronic increase in reactive oxygen species (ROS), accumulation of a low-grade proinflammatory phenotype and reduction in age-related autophagy, suggesting that these factors may play important roles in promoting aging. Indeed, reduction of ROS and low-grade inflammation and promotion of autophagy by calorie restriction or other dietary manipulation can extend lifespan in a wide spectrum of model organisms. Interestingly, recent studies show that some food-derived small molecules, also called phytochemicals, can extend lifespan in various animal species. In this paper, we review several recently identified potential antiaging phytochemicals that have been studied in cells, animals and humans and further highlight the cellular and molecular mechanisms underlying the antiaging actions by these molecules. PMID:24742470

  14. Therapeutic Mechanisms for Cannabinoid-Promoted Survival of Oligodendrocytes

    Science.gov (United States)

    2013-06-21

    on studying the beneficial effects of CB2 receptor activation by using selective CB2 agonists. Although a valid approach, studies show that CB 1...narrow their field to study specific mechanisms in specific cell types, the findings should be better validated in vivo in order to draw more... periodontal inflammation through NF-kappaB pathway inhibition. FEBS Lett 580:613-9 150. Osei-Hyiaman D, Liu J, Zhou L, Godlewski G, Harvey-White J, et al

  15. Why collagens best survived in fossils? Clues from amino acid thermal stability.

    Science.gov (United States)

    Wang, Shuang-Yin; Cappellini, Enrico; Zhang, Hong-Yu

    2012-05-25

    Explaining why type I collagens are preferentially preserved in the geological time scale remains a challenge. Several pieces of evidence indicate that its rich content in the bone and its unique, stable structure played key roles in its preservation. By considering the distinct thermal stability of amino acids, we reveal that the elevated abundance of thermostable amino acid residues in type I collagens also contribute to its survival. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Probiotic bacteria survive in Cheddar cheese and modify populations of other lactic acid bacteria.

    Science.gov (United States)

    Ganesan, B; Weimer, B C; Pinzon, J; Dao Kong, N; Rompato, G; Brothersen, C; McMahon, D J

    2014-06-01

    Starter lactic acid bacteria in Cheddar cheese face physico-chemical stresses during manufacture and ageing that alter their abilities to survive and to interact with other bacterial populations. Nonstarter bacteria are derived from milk handling, cheese equipment and human contact during manufacture. Probiotic bacteria are added to foods for human health benefits that also encounter physiological stresses and microbial competition that may mitigate their survival during ageing. We added probiotic Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus paracasei and Bifidobacterium animalis subsp. lactis to full-fat, reduced-fat and low-fat Cheddar cheeses, aiming to study their survival over 270 days of ageing and to determine the role of the cheese matrix in their survival. Probiotic and other lactic acid bacterial populations were enumerated by quantitative PCR using primers specifically targeting the different bacterial genera or species of interest. Bifidobacteria were initially added at 10(6) CFU g(-1) cheese and survived variably in the different cheeses over the 270-day ageing process. Probiotic lactobacilli that were added at 10(7) CFU g(-1) cheese and incident nonstarter lactobacilli (initially at 10(8) CFU g(-1) cheese) increased by 10- to 100-fold over 270 days. Viable bacterial populations were differentiated using propidium monoazide followed by species-specific qPCR assays, which demonstrated that the starter and probiotic microbes survived over ageing, independent of cheese type. Addition of probiotic bacteria, at levels 100-fold below that of starter bacteria, modified starter and nonstarter bacterial levels. We demonstrated that starter lactococci, nonstarter lactobacilli and probiotic bacteria are capable of surviving throughout the cheesemaking and ageing process, indicating that delivery via hard cheeses is possible. Probiotic addition at lower levels may also alter starter and nonstarter bacterial survival. We applied qPCR to study

  17. Effects of non-protein amino acids on survival and locomotion of Osmia bicornis.

    Science.gov (United States)

    Felicioli, Antonio; Sagona, Simona; Galloni, Marta; Bortolotti, Laura; Bogo, Gherardo; Guarnieri, Massimo; Nepi, Massimo

    2018-04-17

    To investigate the effects of two non-protein amino acids, β-alanine and γ-amino butyric acid (GABA), on Osmia bicornis survival and locomotion, two groups of caged bees were fed with sugar syrup enriched with β-alanine and GABA, respectively. A further control group was fed with sugar syrup. Five behavioural categories were chosen according to the principle of parsimony and intrinsic unitary consistency from start to end, and recorded by scan sampling: two states (remaining under paper or in tubes) and three events (walking on net, feeding from flower and flying). We also analysed the amino acid content of haemolymph sampled from an additional 45 bees fed the same diets (15 per diet type). Bees fed with ß-alanine had a significantly shorter survival than those fed with control and GABA diets. The GABA diet induced higher locomotion than β-alanine. The former non-protein amino acid was only detected in the haemolymph of bees fed GABA. The results suggest that insects consuming non-protein amino-acid-rich diets absorb and transfer these substances to the haemolymph and that non-protein amino acids affect survival and locomotion. Ecological consequences are discussed in the framework of plant reproductive biology. This article is protected by copyright. All rights reserved. © 2018 The Royal Entomological Society.

  18. Natural exopolysaccharides enhance survival of lactic acid bacteria in frozen dairy desserts.

    Science.gov (United States)

    Hong, S H; Marshall, R T

    2001-06-01

    Viable lactic acid-producing bacteria in frozen dairy desserts can be a source of beta-galactosidase for persons who absorb lactose insufficiently. However, freezing kills many of the cells, causing loss of enzymatic activity. Cultures selected for high beta-galactosidase activities and high survival rates in the presence of bile were examined for survivability during freezing in reduced-fat ice cream. Encapsulated S. thermophilus strains survived better than their nonencapsulated mutants in reduced-fat ice cream after freezing and frozen storage at -29 degrees C for 16 d (28 vs. 19%). However, a small nonencapsulated strain of Lactobacillus delbrueckii sp. bulgaricus survived better than the large encapsulated strain in reduced-fat ice cream. Factors that improved survival of encapsulated S. thermophilus 1068 in ice cream were 1) harvest of cells in the late-log phase of growth at 37 degrees C rather than at 40, 42.5, or 45 degrees C; 2) overrun at 50% rather than 100%; and 3) storage at -17 degrees C rather than -23 or -29 degrees C. Survival of strain ST1068 was unaffected by 1) neutralization of acid during growth or 2) substitution of nitrogen for air in building overrun.

  19. Dietary proteins extend the survival of salmonella dublin in a gastric Acid environment

    DEFF Research Database (Denmark)

    Birk, Tina; Kristensen, Kim; Harboe, Anne

    2012-01-01

    The pH of the human stomach is dynamic and changes over time, depending on the composition of the food ingested and a number of host-related factors such as age. To evaluate the number of bacteria surviving the gastric acid barrier, we have developed a simple gastric acid model, in which we...... mimicked the dynamic pH changes in the human stomach. In the present study, model gastric fluid was set up to imitate pH dynamics in the stomachs of young and elderly people after ingestion of a standard meal. To model a serious foodborne pathogen, we followed the survival of Salmonella enterica serotype...... Dublin, and found that the addition of proteins such as pepsin, ovalbumin, and blended turkey meat to the simple gastric acid model significantly delayed pathogen inactivation compared with the control, for which no proteins were added. In contrast, no delay in inactivation was observed in the presence...

  20. Exogenous Modulation of Retinoic Acid Signaling Affects Adult RGC Survival in the Frog Visual System after Optic Nerve Injury.

    Directory of Open Access Journals (Sweden)

    Mildred V Duprey-Díaz

    Full Text Available After lesions to the mammalian optic nerve, the great majority of retinal ganglion cells (RGCs die before their axons have even had a chance to regenerate. Frog RGCs, on the other hand, suffer only an approximately 50% cell loss, and we have previously investigated the mechanisms by which the application of growth factors can increase their survival rate. Retinoic acid (RA is a vitamin A-derived lipophilic molecule that plays major roles during development of the nervous system. The RA signaling pathway is also present in parts of the adult nervous system, and components of it are upregulated after injury in peripheral nerves but not in the CNS. Here we investigate whether RA signaling affects long-term RGC survival at 6 weeks after axotomy. Intraocular injection of all-trans retinoic acid (ATRA, the retinoic acid receptor (RAR type-α agonist AM80, the RARβ agonist CD2314, or the RARγ agonist CD1530, returned axotomized RGC numbers to almost normal levels. On the other hand, inhibition of RA synthesis with disulfiram, or of RAR receptors with the pan-RAR antagonist Ro-41-5253, or the RARβ antagonist LE135E, greatly reduced the survival of the axotomized neurons. Axotomy elicited a strong activation of the MAPK, STAT3 and AKT pathways; this activation was prevented by disulfiram or by RAR antagonists. Finally, addition of exogenous ATRA stimulated the activation of the first two of these pathways. Future experiments will investigate whether these strong survival-promoting effects of RA are mediated via the upregulation of neurotrophins.

  1. KINETICS AND MECHANISM OF REACTION OF ACIDIC ...

    African Journals Online (AJOL)

    For both Nile blue and Meldola\\'s blue reactions the rates have first-order dependence on each substrate, chlorite and acid. Both reactions showed negative salt effect indicating the reaction is between the oppositely charged species, likely the substrate cation and chlorite anion. The acidic chlorite reaction with MB+ was ...

  2. Elucidating the sponge stress response; lipids and fatty acids can facilitate survival under future climate scenarios.

    Science.gov (United States)

    Bennett, Holly; Bell, James J; Davy, Simon K; Webster, Nicole S; Francis, David S

    2018-03-05

    Ocean warming (OW) and ocean acidification (OA) are threatening coral reef ecosystems, with a bleak future forecast for reef-building corals, which are already experiencing global declines in abundance. In contrast, many coral reef sponge species are able to tolerate climate change conditions projected for 2100. To increase our understanding of the mechanisms underpinning this tolerance, we explored the lipid and fatty acid (FA) composition of four sponge species with differing sensitivities to climate change, experimentally exposed to OW and OA levels predicted for 2100, under two CO 2 Representative Concentration Pathways (RCPs). Sponges with greater concentrations of storage lipid, phospholipids, sterols and elevated concentrations of n-3 and n-6 long-chain polyunsaturated FA (LC PUFA), were more resistant to OW. Such biochemical constituents likely contribute to the ability of these sponges to maintain membrane function and cell homeostasis in the face of environmental change. Our results suggest that n-3 and n-6 LC PUFA are important components of the sponge stress response potentially via chain elongation and the eicosanoid stress-signalling pathways. The capacity for sponges to compositionally alter their membrane lipids in response to stress was also explored using a number of specific homeoviscous adaptation (HVA) indicators. This revealed a potential mechanism via which additional CO 2 could facilitate the resistance of phototrophic sponges to thermal stress through an increased synthesis of membrane-stabilising sterols. Finally, OW induced an increase in FA unsaturation in phototrophic sponges but a decrease in heterotrophic species, providing support for a difference in the thermal response pathway between the sponge host and the associated photosymbionts. Here we have shown that sponge lipids and FA are likely to be an important component of the sponge stress response and may play a role in facilitating sponge survival under future climate conditions

  3. Asiatic Acid Prevents the Deleterious Effects of Valproic Acid on Cognition and Hippocampal Cell Proliferation and Survival

    Directory of Open Access Journals (Sweden)

    Jariya Umka Welbat

    2016-05-01

    Full Text Available Valproic acid (VPA is commonly prescribed as an anticonvulsant and mood stabilizer used in the treatment of epilepsy and bipolar disorder. A recent study has demonstrated that VPA reduces histone deacetylase (HDAC activity, an action which is believed to contribute to the effects of VPA on neural stem cell proliferation and differentiation which may explain the cognitive impairments produced in rodents and patients. Asiatic acid is a triterpenoid derived from the medicinal plant Centella asiatica. Our previous study has shown that Asiatic acid improves working spatial memory and increases cell proliferation in the sub granular zone of the hippocampal dentate gyrus. In the present study we investigate the effects of Asiatic acid in preventing the memory and cellular effects of VPA. Male Spraque-Dawley rats were orally administered Asiatic acid (30 mg/kg/day for 28 days, while VPA-treated animals received injections of VPA (300 mg/kg twice a day from Day 15 to Day 28 for 14 days. Spatial memory was determined using the novel object location (NOL test and hippocampal cell proliferation and survival was quantified by immuostaining for Ki-67 and Bromodeoxyuridine (BrdU, respectively. The results showed that VPA-treated animals were unable to discriminate between objects in familiar and novel locations. Moreover, VPA significantly reduced numbers of Ki-67 and BrdU positive cells. These results indicate that VPA treatment caused impairments of spatial working memory, cell proliferation and survival in the subgranular zone (SGZ of the hippocampal dentate gyrus (DG. However, these abnormalities were restored to control levels by co-treatment with Asiatic acid. These data demonstrate that Asiatic acid could prevent the spatial memory and neurogenesis impairments caused by VPA.

  4. Osmotic fragility, sialic acid content and survival of circulating erythrocytes in anemic tumor-bearing mice

    International Nuclear Information System (INIS)

    Ray, M.R.; Roy Chowdhury, J.

    1989-01-01

    The effect of tumor growth on the survival of circulating erythrocytes was studied in mice bearing a wide spectrum of experimental tumors. RBC half-life (t 1/2 ) measured by the 51 Cr-labelling technique decreased significantly (p 51 Cr-labelled RBCs between normal and tumor-bearing animals revealed that both intrinsic and extrinsic factors are responsible for shortened RBC survival. As far as the cellular abnormalities are concerned, the decrease in RBC t 1/2 was not attributable to increased osmotic fragility as the cells were observed to be osmotically more resistant. Similarly, membrane sialic acid content was markedly elevated in the tumor hosts, thus the shortened erythrocyte life-span cannot be attributed to decrease in sialic acid content of the erythrocyte membrane. (author). 6 tabs., 16 refs

  5. Survival of Four Probiotic Strains in Acid, Bile Salt and After Spray Drying

    OpenAIRE

    Rawichar Chaipojjana; Suttipong Phosuksirikul; Arunsri Leejeerajumnean

    2014-01-01

    The objective of the study was to select the survival of probiotic strains when exposed to acidic and bile salts condition. Four probiotic strains Lactobacillus casei subsp. rhamnosus TISTR 047, Lactobacillus casei TISTR 1500, Lactobacillus acidophilus TISTR 1338 and Lactobacillus plantarum TISTR 1465 were cultured in MRS broth and incubated at 35ºC for 15 hours before being inoculated into acidic condition 5 M HCl, pH 2 for 2 hours and bile salt 0.3%, pH 5.8 for 8 hour. ...

  6. Survival of Salmonella serovars on beef carcasses and molecular mechanisms to survive low temperature stress and desiccation

    DEFF Research Database (Denmark)

    Knudsen, Gitte Maegaard; Thomsen, Line Elnif; Aabo, Søren

    2006-01-01

    . Infantis and S. Newport. This experiment indicates that storage at low temperature of beef carcasses can be used as a reduction strategy for Salmonella spp. in beef. In addition molecular mechanisms to resist low temperature stress and desiccation have been investigated. Mutants in the otsA, rpoS and clp...... at 10°C and 15°C, the ¿clpP mutant was severely affected in ability to form colonies compared to the wildtype. Neither the ¿otsA nor the ¿rpoS were affected in growth or survival at low temperature. In a desiccation model, both the ¿rpoS and ¿clpP mutant were more sensitive than the C5 wildtype...

  7. Sulfuric acid leaching of mechanically activated manganese carbonate ore

    Directory of Open Access Journals (Sweden)

    Kenan Yıldız

    2010-06-01

    Full Text Available Acidic leaching of mechanically activated manganese ore from Denizli – Tavas was investigated. The ore was activated mechanically in a planetary mill and the amorphisation in manganese structure was analyzed with X-ray diffraction. The parameters in acidic leaching of the ore were milling time, acid concentration and time. All experiments were performed at 25°C with solid to liquid ratio: 1/10. The activation procedure led to amorphization and structural disordering in manganese ore and accelerated the dissolution of manganese in acidic media.

  8. The mechanism and properties of acid-coagulated milk gels

    Directory of Open Access Journals (Sweden)

    Chanokphat Phadungath

    2005-03-01

    Full Text Available Acid-coagulated milk products such as fresh acid-coagulated cheese varieties and yogurt areimportant dairy food products. However, little is known regarding the mechanisms involved in gel formation, physical properties of acid gels, and the effects of processing variables such as heat treatment and gelation temperature on the important physical properties of acid milk gels. This paper reviews the modern concepts of possible mechanisms involved in the formation of particle milk gel aggregation, along with recent developments including the use of techniques such as dynamic low amplitude oscillatory rheology to observe the gel formation process, and confocal laser scanning microscopy to monitor gel microstructure.

  9. Crassulacean Acid Metabolism Permutation and Survival of Caralluma Species (Apocynaceae in Arid Habitats

    Directory of Open Access Journals (Sweden)

    Yahya S. Masrahi

    2012-07-01

    Full Text Available Several species of the stem succulent Caralluma (Apocynaceae are abundant perennials in arid regions of the Arabian Peninsula. These arid regions have a short wet season with erratic rainfall and are characterized by harsh climatic conditions of high temperature, high evaporation and sand storms. Work presented in this paper aimed at investigating importance of Crassulacean Acid Metabolism (CAM for survival of three Caralluma species in their natural habitat. Investigations involved studying stomatal characteristics, stomatal diffusive conductance, chlorophyll fluorescence, and CAM in three species of Caralluma, namely C. acutangula (Decne. N.E.Br., C. edulis (Edgew. Benth. ex Hook.f., and C. subulata (Forssk. Decne. Microscopic examination revealed a pattern of stomatal characteristics typical of CAM plants in these three Caralluma species. Results showed that these three Caralluma species were obligate CAM plants exhibiting this mode of photosynthesis during both the wet and the dry seasons. Under protracted water stress during the long dry season very low values of stomatal diffusive conductance and dampening of CAM acidification-deacidification cycles denoted the tendency of these three Caralluma species to shift from the obligate CAM physiotype to CAM-idling mode. Chlorophyll fluorescence measurements indicated that protracted water stress induced a reduction in Photosystem II (PSII antenna efficiency and quantum yield in the three studied Caralluma species. This reduction of PSII activity occurred in concomitance with a marked rise in non-photochemical quenching of chlorophyll fluorescence denoting operation of non-photochemical energy dissipating mechanisms known to be important for photoprotection of the photosynthetic apparatus.

  10. Antihypertensive effects and mechanisms of chlorogenic acids.

    Science.gov (United States)

    Zhao, Youyou; Wang, Junkuan; Ballevre, Olivier; Luo, Hongliang; Zhang, Weiguo

    2012-04-01

    Chlorogenic acids (CGAs) are potent antioxidants found in certain foods and drinks, most notably in coffee. In recent years, basic and clinical investigations have implied that the consumption of chlorogenic acid can have an anti-hypertension effect. Mechanistically, the metabolites of CGAs attenuate oxidative stress (reactive oxygen species), which leads to the benefit of blood-pressure reduction through improved endothelial function and nitric oxide bioavailability in the arterial vasculature. This review article highlights the physiological and biochemical findings on this subject and highlights some remaining issues that merit further scientific and clinical exploration. In the framework of lifestyle modification for the management of cardiovascular risk factors, the dietary consumption of CGAs may hold promise for providing a non-pharmacological approach for the prevention and treatment of high blood pressure.

  11. Mechanisms Regulating Acid-Base Transporter Expression in Breast- and Pancreatic Cancer

    DEFF Research Database (Denmark)

    Gorbatenko, Andrej

    , characteristics of which are a shift towards glycolytic metabolism and increased acid production. HER2 receptor overexpression in breast cancer leads to further increased glycolysis, invasion and metastasis, drug resistance and poor prognosis. Increased tumor glycolysis requires acquisition of mechanisms...... for dealing with excess acid production. In this light, evidence accumulates on the importance of pH regulatory proteins to cancer cell survival and motility. Our group previously demonstrated upregulation of the Na+/HCO3 - co-transporter NBCn1 (SLC4A7) by a constitutively active form of HER2 receptor (p95HER...

  12. Influence of ethanol adaptation on Salmonella enterica serovar Enteritidis survival in acidic environments and expression of acid tolerance-related genes.

    Science.gov (United States)

    He, Shoukui; Cui, Yan; Qin, Xiaojie; Zhang, Fen; Shi, Chunlei; Paoli, George C; Shi, Xianming

    2018-06-01

    Cross-protection to environmental stresses by ethanol adaptation in Salmonella poses a great threat to food safety because it can undermine food processing interventions. The ability of Salmonella enterica serovar Enteritidis (S. Enteritidis) to develop acid resistance following ethanol adaptation (5% ethanol for 1 h) was evaluated in this study. Ethanol-adapted S. Enteritidis mounted cross-tolerance to malic acid (a two-fold increase in minimum bactericidal concentration), but not to acetic, ascorbic, lactic, citric and hydrochloric acids. The population of S. Enteritidis in orange juice (pH 3.77) over a 48-h period was not significantly (p > 0.05) influenced by ethanol adaptation. However, an increased survival by 0.09-1.02 log CFU/ml was noted with ethanol-adapted cells of S. Enteritidis compared to non-adapted cells in apple juice (pH 3.57) stored at 25 °C (p < 0.05), but not at 4 °C. RT-qPCR revealed upregulation of two acid tolerance-related genes, rpoS (encoding σ S ) and SEN1564A (encoding an acid shock protein), following ethanol adaptation. The relative expression level of the acid resistance gene hdeB did not change. The resistance phenotypes and transcriptional profiles of S. Enteritidis suggest some involvement of rpoS and SEN1564A in the ethanol-induced acid tolerance mechanism. Copyright © 2017. Published by Elsevier Ltd.

  13. Docosahexaenoic acid (DHA in stroke, Alzheimer’s disease, and blinding retinal degenerations: coping with neuroinflammation and sustaining cell survival

    Directory of Open Access Journals (Sweden)

    Bazan Nicolas G.

    2011-07-01

    Full Text Available The significance of the selective enrichment in omega-3 essential fatty acids in the nervous system has remained, until recently, incompletely understood. While studying mechanisms of cell survival in neurodegenerations, a new docosanoid synthesized from docosahexaenoic acid [DHA] by 15-lipoxygenase-1 [15-LOX-1] was discovered. This mediator, called neuroprotectin D1 [NPD1], is a docosanoid because it is derived from a 22C precursor (DHA, unlike eicosanoids, which are derived from the 20 C arachidonic acid family member of essential fatty acids not enriched in the nervous system. NPD1 is promptly made in response to oxidative stress and brain ischemiareperfusion and in the presence of neurotrophins. NPD1 is neuroprotective in experimental brain damage, oxidative-stressed retinal pigment epithelial [RPE] cells, and in human brain cells exposed to amyloid-b peptide. Thus NPD1 is a protective sentinel, one of the very first defenses activated when cell homeostasis is threatened by neurodegenerations. This review highlights the specificity and potency of NPD1 spanning beneficial bioactivity in experimental models of stroke, in retinal cells relevant to early events in age-related macular degenerations, and studies addressing fundamental issues during initiation and early progression of neurodegenerations.

  14. Analysis of proteins responsive to acetic acid in Acetobacter: molecular mechanisms conferring acetic acid resistance in acetic acid bacteria.

    Science.gov (United States)

    Nakano, Shigeru; Fukaya, Masahiro

    2008-06-30

    Acetic acid bacteria are used for industrial vinegar production because of their remarkable ability to oxidize ethanol and high resistance to acetic acid. Although several molecular machineries responsible for acetic acid resistance in acetic acid bacteria have been reported, the entire mechanism that confers acetic acid resistance has not been completely understood. One of the promising methods to elucidate the entire mechanism is global analysis of proteins responsive to acetic acid by two-dimensional gel electrophoresis. Recently, two proteins whose production was greatly enhanced by acetic acid in Acetobacter aceti were identified to be aconitase and a putative ABC-transporter, respectively; furthermore, overexpression or disruption of the genes encoding these proteins affected acetic acid resistance in A. aceti, indicating that these proteins are involved in acetic acid resistance. Overexpression of each gene increased acetic acid resistance in Acetobacter, which resulted in an improvement in the productivity of acetic acid fermentation. Taken together, the results of the proteomic analysis and those of previous studies indicate that acetic acid resistance in acetic acid bacteria is conferred by several mechanisms. These findings also provide a clue to breed a strain having high resistance to acetic acid for vinegar fermentation.

  15. Kinetics and mechanism of the oxidation of some -hydroxy acids ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 116; Issue 6. Kinetics and mechanism of the oxidation of some -hydroxy acids by hexamethylenetetramine-bromine ... The oxidation of -deuteriomandelic acid exhibits the presence of a substantial kinetic isotope effect (/ = 5.91 at 298 K). The rates of ...

  16. Antiobesity mechanisms of action of conjugated linoleic acid

    DEFF Research Database (Denmark)

    Kennedy, Arion; Martinez, Kristina; Schmidt, Soren

    2010-01-01

    Conjugated linoleic acid (CLA), a family of fatty acids found in beef, dairy foods and dietary supplements, reduces adiposity in several animal models of obesity and some human studies. However, the isomer-specific antiobesity mechanisms of action of CLA are unclear, and its use in humans...

  17. Mechanisms of redox metabolism and cancer cell survival during extracellular matrix detachment.

    Science.gov (United States)

    Hawk, Mark A; Schafer, Zachary T

    2018-01-16

    Non-transformed cells that become detached from the extracellular matrix (ECM) undergo dysregulation of redox homeostasis and cell death. In contrast, cancer cells often acquire the ability to mitigate programmed cell death pathways and recalibrate the redox balance to survive after ECM detachment, facilitating metastatic dissemination. Accordingly, recent studies of the mechanisms by which cancer cells overcome ECM detachment-induced metabolic alterations have focused on mechanisms in redox homeostasis. The insights into these mechanisms may inform the development of therapeutics that manipulate redox homeostasis to eliminate ECM-detached cancer cells. Here, we review how ECM-detached cancer cells balance redox metabolism for survival. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid

    Directory of Open Access Journals (Sweden)

    Sergio eGiannattasio

    2013-02-01

    Full Text Available Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications.

  19. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid.

    Science.gov (United States)

    Giannattasio, Sergio; Guaragnella, Nicoletta; Zdralević, Maša; Marra, Ersilia

    2013-01-01

    Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications.

  20. Mechanisms controlling renal hemodynamics and electrolyte excretion during amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Woods, L.L.; Mizelle, H.L.; Montani, J.P.; Hall, J.E.

    1986-08-01

    Our purpose was to investigate the mechanisms by which increased plasma amino acids elevate renal blood flow (RBF) and glomerular filtration rate (GFR). Since transport of amino acids and Na is linked in the proximal tubule, the authors hypothesized that increased amino acids might stimulate proximal tubular Na reabsorption (PR/sub Na/) and thus increase RBF and GFR by a macula densa feedback mechanism. A solution of four amino acids (Ala, Ser, Gly, Pro) was infused intravenously into anesthetized dogs with normal kidneys (NK) and with kidneys in which the tubuloglomerular feedback mechanism was blunted by lowering renal artery pressure (LPK) or blocked by making the kidneys nonfiltering (NFK). In NK, RBF and GFR increased by 35 +/- 4% and 30 +/- 7% after 90 min of amino acid infusion, while PR/sub Na/ (estimated from lithium clearance) and O2 consumption increased by 31 +/- 5% and 29 +/- 5% and distal Na delivery remained relatively constant. Autoregulation of RBF and GFR in response to step deceases in renal artery pressure was impaired during amino acids in NK. The hemodynamic responses to amino acids were abolished in LPK and NFK. Infusion of the nonmetabolized -aminoisobutyric acid into NK produced changes in renal hemodynamics that were similar to the responses observed with the four metabolizable amino acids. These data are consistent with the hypothesis that elevation of plasma amino acids increases RBF and GFR by a mechanism that requires an intact macula densa feedback. Metabolism of the amino acids does not appear to be necessary for these changes to occur.

  1. Mechanisms controlling renal hemodynamics and electrolyte excretion during amino acids

    International Nuclear Information System (INIS)

    Woods, L.L.; Mizelle, H.L.; Montani, J.P.; Hall, J.E.

    1986-01-01

    Our purpose was to investigate the mechanisms by which increased plasma amino acids elevate renal blood flow (RBF) and glomerular filtration rate (GFR). Since transport of amino acids and Na + is linked in the proximal tubule, the authors hypothesized that increased amino acids might stimulate proximal tubular Na + reabsorption (PR/sub Na/) and thus increase RBF and GFR by a macula densa feedback mechanism. A solution of four amino acids (Ala, Ser, Gly, Pro) was infused intravenously into anesthetized dogs with normal kidneys (NK) and with kidneys in which the tubuloglomerular feedback mechanism was blunted by lowering renal artery pressure (LPK) or blocked by making the kidneys nonfiltering (NFK). In NK, RBF and GFR increased by 35 +/- 4% and 30 +/- 7% after 90 min of amino acid infusion, while PR/sub Na/ (estimated from lithium clearance) and O 2 consumption increased by 31 +/- 5% and 29 +/- 5% and distal Na + delivery remained relatively constant. Autoregulation of RBF and GFR in response to step deceases in renal artery pressure was impaired during amino acids in NK. The hemodynamic responses to amino acids were abolished in LPK and NFK. Infusion of the nonmetabolized α-aminoisobutyric acid into NK produced changes in renal hemodynamics that were similar to the responses observed with the four metabolizable amino acids. These data are consistent with the hypothesis that elevation of plasma amino acids increases RBF and GFR by a mechanism that requires an intact macula densa feedback. Metabolism of the amino acids does not appear to be necessary for these changes to occur

  2. Survival of the functional yeast Kluyveromyces marxianus B0399 in fermented milk with added sorbic acid.

    Science.gov (United States)

    Tabanelli, G; Verardo, V; Pasini, F; Cavina, P; Lanciotti, R; Caboni, M F; Gardini, F; Montanari, C

    2016-01-01

    In this study, the survival of the functional yeast Kluyveromyces marxianus B0399 in an industrially produced fermented milk was evaluated. In particular, the yeast viability was assessed throughout the entire shelf-life of the product (30 d) to ensure the presence of the effective yeast dose (20 million viable cells for each serving of 125 g) while avoiding, by sorbic acid addition, yeast growth, which could affect product quality and stability. To find the best combination of yeast and sorbic acid concentration, 13 different combinations were tested, and then 2 of them were chosen for industrial production. In production at lower concentrations (30 million viable cells, 150 mg/kg of sorbic acid) the effective dose was maintained only at 4 and 6°C, whereas at higher dosages (70 million viable cells, 250 mg/kg of sorbic acid) the effect of temperature was less evident. In all the trials, the concentration of sorbic acid was not affected by microbial metabolism and remained stable throughout the entire shelf-life. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  3. Mechanisms of Sensorineural Cell Damage, Death and Survival in the Cochlea

    Directory of Open Access Journals (Sweden)

    Allen Frederic Ryan

    2015-04-01

    Full Text Available The majority of acquired hearing loss, including presbycusis, is caused by irreversible damage to the sensorineural tissues of the cochlea. This article reviews the intracellular mechanisms that contribute to sensorineural damage in the cochlea, as well as the survival signaling pathways that can provide endogenous protection and tissue rescue. These data have primarily been generated in hearing loss not directly related to age. However, there is evidence that similar mechanisms operate in presbycusis. Moreover, accumulation of damage from other causes can contribute to age-related hearing loss. Potential therapeutic interventions to balance opposing but interconnected cell damage and survival pathways, such as antioxidants, anti-apoptotics, and pro-inflammatory cytokine inhibitors, are also discussed.

  4. Impact of Acetic Acid on the Survival of L. plantarum upon Microencapsulation by Coaxial Electrospraying

    Directory of Open Access Journals (Sweden)

    Laura G. Gómez-Mascaraque

    2017-01-01

    Full Text Available In this work, coaxial electrospraying was used for the first time to microencapsulate probiotic bacteria, specifically Lactobacillus plantarum, within edible protein particles with the aim of improving their resistance to in vitro digestion. The developed structures, based on an inner core of whey protein concentrate and an outer layer of gelatin, were obtained in the presence of acetic acid in the outer solution as a requirement for the electrospraying of gelatin. Despite the limited contact of the inner suspension and outer solution during electrospraying, the combination of the high voltage used during electrospraying with the presence of acetic acid was found to have a severe impact on the lactobacilli, not only decreasing initial viability but also negatively affecting the survival of the bacteria during storage and their resistance to different stress conditions, including simulated in vitro digestion.

  5. Molecular mechanisms for sweet-suppressing effect of gymnemic acids.

    Science.gov (United States)

    Sanematsu, Keisuke; Kusakabe, Yuko; Shigemura, Noriatsu; Hirokawa, Takatsugu; Nakamura, Seiji; Imoto, Toshiaki; Ninomiya, Yuzo

    2014-09-12

    Gymnemic acids are triterpene glycosides that selectively suppress taste responses to various sweet substances in humans but not in mice. This sweet-suppressing effect of gymnemic acids is diminished by rinsing the tongue with γ-cyclodextrin (γ-CD). However, little is known about the molecular mechanisms underlying the sweet-suppressing effect of gymnemic acids and the interaction between gymnemic acids versus sweet taste receptor and/or γ-CD. To investigate whether gymnemic acids directly interact with human (h) sweet receptor hT1R2 + hT1R3, we used the sweet receptor T1R2 + T1R3 assay in transiently transfected HEK293 cells. Similar to previous studies in humans and mice, gymnemic acids (100 μg/ml) inhibited the [Ca(2+)]i responses to sweet compounds in HEK293 cells heterologously expressing hT1R2 + hT1R3 but not in those expressing the mouse (m) sweet receptor mT1R2 + mT1R3. The effect of gymnemic acids rapidly disappeared after rinsing the HEK293 cells with γ-CD. Using mixed species pairings of human and mouse sweet receptor subunits and chimeras, we determined that the transmembrane domain of hT1R3 was mainly required for the sweet-suppressing effect of gymnemic acids. Directed mutagenesis in the transmembrane domain of hT1R3 revealed that the interaction site for gymnemic acids shared the amino acid residues that determined the sensitivity to another sweet antagonist, lactisole. Glucuronic acid, which is the common structure of gymnemic acids, also reduced sensitivity to sweet compounds. In our models, gymnemic acids were predicted to dock to a binding pocket within the transmembrane domain of hT1R3. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Survival and growth of wildlife shrubs and trees on acid mine spoil

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, D.K.; Adkisson, L.F.

    1980-01-01

    The purpose of this study was to assess the survival and growth of selected wildlife plants over a wide range of acid mine spoil conditions and to identify species suitable for surface mine reclamation. A major criterion in selection of study sites was inclusion of a wide range of spoil acidity conditions. The Ollis Creek (Study Area A) and Farrell (Study Area B) coal surface mines located in Campbell and Scott Counties, Tennessee, were selected for study. Seven plant species, all of which had been used in past reclamation demonstrations, were introduced on the 22 plots during March 1972. Autumn olive (Elaeagnus umbellata) was included as a control plant. Ten additional plant species were introduced during March 1973. With the exception of highbush blueberry (Vaccinium corymbosum var.). European filbert (Corylus avellana), and red maple (Acer rubrum), these species had not been used in TVA reclamation demonstrations. To assess the effects of spoil pH on the plants, the plots were grouped into seven pH categories, and mean percent survival and growth for each species were calculated. Results indicate that autumn olive, elaeagnus cherry, arnot locust, sawtooth oak, red maple, and Toringo crabapple are suitable for quick improvement of surface mine habitat over a wide range of spoil acidity in the Appalachian coalfield. Bessey cherry and European filbert need further study before a decision can be made regarding their reclamation utility. Species that are not recommended for quick habitat improvement over a wide range of surface mine spoil pH conditions include bush honeysuckle, barberry, Siberian crabapple, Manchu cherry, American beautyberry, bear oak, blueberry, rem-red honeysuckle, and redcedar.

  7. Neuroprotective Effect of Uncaria rhynchophylla in Kainic Acid-Induced Epileptic Seizures by Modulating Hippocampal Mossy Fiber Sprouting, Neuron Survival, Astrocyte Proliferation, and S100B Expression

    Directory of Open Access Journals (Sweden)

    Chung-Hsiang Liu

    2012-01-01

    Full Text Available Uncaria rhynchophylla (UR, which is a traditional Chinese medicine, has anticonvulsive effect in our previous studies, and the cellular mechanisms behind this are still little known. Because of this, we wanted to determine the importance of the role of UR on kainic acid- (KA- induced epilepsy. Oral UR for 6 weeks can successfully attenuate the onset of epileptic seizure in animal tests. Hippocampal mossy fiber sprouting dramatically decreased, while neuronal survival increased with UR treatment in hippocampal CA1 and CA3 areas. Furthermore, oral UR for 6 weeks significantly attenuated the overexpression of astrocyte proliferation and S100B proteins but not γ-aminobutyric acid A (GABAA receptors. These results indicate that oral UR for 6 weeks can successfully attenuate mossy fiber sprouting, astrocyte proliferation, and S100B protein overexpression and increase neuronal survival in KA-induced epileptic rat hippocampus

  8. Applications of hydroxy acids: classification, mechanisms, and photoactivity

    Directory of Open Access Journals (Sweden)

    Andrija Kornhauser

    2010-11-01

    Full Text Available Andrija Kornhauser1, Sergio G Coelho2, Vincent J Hearing21US Food and Drug Administration [retired], Annandale, VA, USA; 2Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USAAbstract: Hydroxy acids (HAs represent a class of compounds which have been widely used in a number of cosmetic and therapeutic formulations in order to achieve a variety of beneficial effects for the skin. We review and discuss the most frequently used classes of these compounds, such as a-hydroxy acids, β-hydroxy acids, polyhydroxy acids, and bionic acids, and describe their applications as cosmetic and therapeutic agents. Special emphasis is devoted to the safety evaluation of these formulations, in particular on the effects of their prolonged use on sun-exposed skin. Furthermore, we summarize the very limited number of studies dealing with the modifications evoked by topical application of products containing HAs on photocarcinogenesis. In spite of the large number of reports on the cosmetic and clinical effects of HAs, their biological mechanism(s of action still require more clarification. Some of these mechanisms are discussed in this article along with important findings on the effect of HAs on melanogenesis and on tanning. We also emphasize the important contribution of cosmetic vehicles in these types of studies. Thus, HAs play an important role in cosmetic formulations, as well as in many dermatologic applications, such as in treating photoaging, acne, ichthyosis, rosacea, pigmentation disorders, and psoriasis.Keywords: hydroxy acids, glycolic acid, salicylic acid, UV, erythema, cosmetics

  9. Nuclear barrier hypothesis of aging as mechanism for trade-off growth to survival.

    Science.gov (United States)

    Park, Sang Chul

    2011-01-01

    When the aging-dependent cellular behaviors toward growth factors and toxic stress have been analyzed, the perinuclear accumulation of the activated signals, either mitogenic or apoptotic, has been observed, suggesting the aging-dependent inefficiency of the nucleocytoplasmic trafficking of the signals. Thereby, it would be natural to assume the operation of the functional nuclear barrier in aging-dependent manner, which would be designated as "Park and Lim's Barrier." And for the ultimate transcriptional factor for these aging-dependent changes of the functional nuclear barrier, Sp1 transcriptional factor has been suggested to be the most probable candidate. This novel mechanism of aging-dependent operation of the functional nuclear barrier is proposed as the ultimate checking mechanism for cellular protection against toxic environment and the general mechanism for the trade-off growth to survival in aging.

  10. Mechanism of acid-induced folding of proteins.

    Science.gov (United States)

    Goto, Y; Takahashi, N; Fink, A L

    1990-04-10

    We have previously shown [Goto, Y., Calciano, L. J., & Fink, A. L. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 573-577] that beta-lactamase, cytochrome c, and apomyoglobin are maximally unfolded at pH 2 under conditions of low ionic strength, but a further decrease in pH, by increasing the concentration of HCl, refolds the proteins to the A state with properties similar to those of a molten globule state. To understand the mechanism of acid-induced refolding of protein structure, we studied the effects of various strong acids and their neutral salts on the acid-unfolded states of ferricytochrome c and apomyoglobin. The conformational transition of cytochrome c was monitored at 20 degrees C by using changes in the far-UV CD and in the Soret absorption at 394 nm, and that of apomyoglobin was monitored by changes in the far-UV CD. Various strong acids (i.e., sulfuric acid, perchloric acid, nitric acid, trichloroacetic acid, and trifluoroacetic acid) refolded the acid-unfolded cytochrome c and apomyoglobin to the A states as was the case with HCl. For both proteins neutral salts of these acids caused similar conformational transitions, confirming that the anions are responsible for bringing about the transition. The order of effectiveness of anions was shown to be ferricyanide greater than ferrocyanide greater than sulfate greater than thiocyanate greater than perchlorate greater than iodide greater than nitrate greater than trifluoroacetate greater than bromide greater than chloride.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Acid tolerance response induced in the biocontrol agent Pantoea agglomerans CPA-2 and effect on its survival ability in acidic environments.

    Science.gov (United States)

    Cañamás, T P; Viñas, I; Abadias, M; Usall, J; Torres, R; Teixidó, N

    2009-01-01

    The aim of this work was to optimize acid stress conditions for induction of acid tolerance response (ATR) in the biocontrol agent Pantoea agglomerans and study the effect of ATR induced on the ability to survive under acidic conditions. Initially, Pantoea agglomerans was grown in mild acidic conditions (pH 6.0, 5.5, 5.0 and 4.0) in order to induce ATR. The highest ATR was induced at initial pH of 5 using malic or citric acid. A first in vitro experiment was carried out. Thus, basal liquid medium at different pHs (3.0, 3.5, 4.0 and non-acidified) were then inoculated with acid-adapted and non-adapted inocula of P. agglomerans and survivals were examined during incubation at 25 or 4 degrees C. It was found that acid adaptation enhanced the survivals of Pantoea agglomerans CPA-2 cells at pH levels at which the cells were unable to grow (Pantoea agglomerans to mild acidic conditions could induce acid resistance in this biocontrol agent.

  12. Decomposition mechanism of chromite in sulfuric acid-dichromic acid solution

    Science.gov (United States)

    Zhao, Qing; Liu, Cheng-jun; Li, Bao-kuan; Jiang, Mao-fa

    2017-12-01

    The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly understood. In this work, binary spinels of Mg-Al, Mg-Fe, and Mg-Cr in the powdered and lump states were synthesized and used as raw materials to investigate the decomposition mechanism of chromite in sulfuric acid-dichromic acid solution. The leaching yields of metallic elements and the changes in morphology of the spinel were studied. The experimental results showed that the three spinels were stable in sulfuric acid solution and that dichromic acid had little influence on the decomposition behavior of the Mg-Al spinel and Mg-Fe spinel because Mg2+, Al3+, and Fe3+ in spinels cannot be oxidized by Cr6+. However, in the case of the Mg-Cr spinel, dichromic acid substantially promoted the decomposition efficiency and functioned as a catalyst. The decomposition mechanism of chromite in sulfuric acid-dichromic acid solution was illustrated on the basis of the findings of this study.

  13. Effects of Acid treatment on the compression and mechanical ...

    African Journals Online (AJOL)

    This study investigated the effect of acid treatment on the compression and mechanical properties of the cellulosic fibrous residue obtained after a high proportion of starch has been removed from the peeled and rasped tuberous root of Xanthosoma sagittifolium (Family: Araceae). Powdered fibrous residues were subjected ...

  14. Formation mechanism of coamorphous drug−amino acid mixtures

    DEFF Research Database (Denmark)

    Jensen, Katrine Birgitte Tarp; Larsen, Flemming Hofmann; Cornett, Claus

    2015-01-01

    Two coamorphous drug−amino acid systems, indomethacin−tryptophan (Ind−Trp) and furosemide−tryptophan Fur−Trp), were analyzed toward their ease of amorphization and mechanism of coamorphization during ball milling. The two mixtures were compared to the corresponding amorphization of the pure drug...

  15. Dissolution kinetics and mechanism of pandermite in acetic acid ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-06-07

    Jun 7, 2010 ... In this study, the dissolution kinetics and mechanism of pandermite mineral was investigated using a batch reactor employing the parameters of particle size, acid concentration, solid/liquid ratio, stirring speed and reaction temperature. From experimental data, it was determined that the conversion rate of.

  16. Effect of Hydrochloric Acid, Mechanical Scarification, Wet Heat ...

    African Journals Online (AJOL)

    Michael Horsfall

    variance showed significant differences between the treatments, the leaves and seedling height performed better than the control(untreated seeds), wet heat, mechanical scarification and 50% hydrochloric acid were found to induce germination of the dormant seeds of Parkia biglobosa These methods could be applied to ...

  17. Effects of sulphuric acid, mechanical scarification and wet heat ...

    African Journals Online (AJOL)

    Effects of different treatment methods on the germination of seeds of Parkia biglobosa (mimosaceae) were carried out. Prior treatment of seeds with sulphuric acid, wet heat and mechanical scarification were found to induce germination of the dormant seeds. These methods could be applied to raise seedlings of the plant for ...

  18. Survival of Escherichia coli O157:H7 in synthetic gastric fluid after cold and acid habituation in apple juice or trypticase soy broth acidified with hydrochloric acid or organic acids.

    Science.gov (United States)

    Uljas, H E; Ingham, S C

    1998-08-01

    Extreme acid tolerance of Escherichia coli O157:H7 has raised doubts about the safety of acidic foods. This study examined whether prior storage in acidic and/or cold conditions enhanced survival of E. coli O157:H7 in synthetic gastric fluid (SGF). Three E. coli O157:H7 strains were stored in trypticase soy broth (TSB; acidified with HCl, malic acid, citric acid, or lactic acid) or pH 3.5 and 6.5 (nonacidic control) apple juice at 4 and 21 degrees C for acids, suggesting that juice constituents other than organic acids protect E. coli O157:H7. Refrigeration combined with low pH best protected cells in apple juice and acidified TSB, but, compared to the nonacidic control, only acidified TSB enhanced subsequent survival in pH 2.5 SGF. Equal survival in SGF occurred after storage in pH 3.5 or 6.5 apple juice at 4 degrees C, suggesting that low temperature alone in apple juice enhanced acid tolerance. Two strains stored at 4 degrees C in TSB containing malic or citric acid subsequently survived better in SGF than cells stored in nonacidified TSB but poorer than cells stored in the presence of HCl. These differences reflect the higher pKa of these organic acids. However, subsequent survival of these strains in SGF was poorer after refrigerated storage in apple juice than in TSB containing citric or malic acids. Cells stored in lactic acid were most likely to be completely eliminated upon transfer to SGF. Differences in survival in storage media or SGF related to strain, storage conditions, or acidifier were consistent and often statistically significant (P acidic beverages may not be affected by the type of acidifier used, the subsequent survival in SGF of this pathogen may be critically dependent on this factor.

  19. The Ross procedure offers excellent survival compared with mechanical aortic valve replacement in a real-world setting.

    Science.gov (United States)

    Andreas, Martin; Wiedemann, Dominik; Seebacher, Gernot; Rath, Claus; Aref, Tandis; Rosenhek, Raphael; Heinze, Georg; Eigenbauer, Ernst; Simon, Paul; Ruetzler, Kurt; Hiesmayr, Joerg-Michael; Moritz, Anton; Laufer, Guenther; Kocher, Alfred

    2014-09-01

    The ideal prosthesis for young patients requiring aortic valve replacement has not been defined to date. Although the Ross procedure provides excellent survival, its application is still limited. We compared the long-term survival after the Ross procedure with mechanical aortic valve replacement. All consecutive Ross procedures and mechanical aortic valve replacements performed between 1991 and 2008 at a single centre were analysed. Only adult patients between 18 and 50 years of age were included in the study. Survival and valve-related complications were evaluated. Furthermore, survival was compared with the age- and sex-matched Austrian population. A total of 159 Ross patients and 173 mechanical valve patients were included. The cumulative survival for the Ross procedure was significantly better, with survival rates of 96, 94 and 93% at 5, 10 and 15 years, respectively, in comparison to 90, 84 and 75% (P Ross group but was significantly reduced in the mechanical valve group. In a real-world setting, the Ross procedure is associated with a long-term survival benefit in young adults in comparison to mechanical aortic valve replacement. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  20. [A study on the survival mechanism of the reverse-flow axial skin flap].

    Science.gov (United States)

    Ya, Zumeng; Chen, Zongji

    2002-07-01

    To investigate the survival mechanisms of the reverse-flow flap. A skin flap measuring 8.0 cm x 2.5 cm based on the left deep circumflex iliac vessel (DCIV) was designed and elevated on the rat's dorsum with 4.0 cm of it's length crossing the midline. The flap was served as the reverse-flow flap model. The survival area, the dynamic microcirculation including flow direction, microvessel number, caliber, pressure and vasculature were assessed respectively at 6 hour, 24 hour, 48 hour, 72 hour, 7 day and 14 day after operation. The average gradient of perfusion pressure was 0 kPa before operation and was 4.9 KPa postoperatively between the proximal and the distal site of the flap. By anastomosis of bilateral DCIV, the blood flow run in a reversed pattern in the region distal to the midline. No venous valves were observed. Distal congestion developed in 20% of the flaps within 72 h. After that, the number and caliber of venous anastomosis increased with pressure dropping in the midline region. The axial vessels extended its branches progressively along the dilated anastomotic rami. As a result, the vasculature of the flap became similar to that of the conventional axial flap by the 14th day. With these changes, flap congestion was alleviated gradually and subsided within 7 days. All the flaps survived completely. Anastomosis connecting the two axial vessels is the circulation route of the reverse-flow flap. By the gradient pressure between the proximal and distal region, blood is driven reversely. Within 72 h, the distal part is susceptible to congestion. In this period, increasing number and caliber and decreasing pressure of anastomosis is important mechanism to support the circulation. After that, the new vasculature similar to the conventional axial flap provides the flap with reliable and permanent blood supply.

  1. Cisplatin Resistant Spheroids Model Clinically Relevant Survival Mechanisms in Ovarian Tumors.

    Directory of Open Access Journals (Sweden)

    Winyoo Chowanadisai

    Full Text Available The majority of ovarian tumors eventually recur in a drug resistant form. Using cisplatin sensitive and resistant cell lines assembled into 3D spheroids we profiled gene expression and identified candidate mechanisms and biological pathways associated with cisplatin resistance. OVCAR-8 human ovarian carcinoma cells were exposed to sub-lethal concentrations of cisplatin to create a matched cisplatin-resistant cell line, OVCAR-8R. Genome-wide gene expression profiling of sensitive and resistant ovarian cancer spheroids identified 3,331 significantly differentially expressed probesets coding for 3,139 distinct protein-coding genes (Fc >2, FDR < 0.05 (S2 Table. Despite significant expression changes in some transporters including MDR1, cisplatin resistance was not associated with differences in intracellular cisplatin concentration. Cisplatin resistant cells were significantly enriched for a mesenchymal gene expression signature. OVCAR-8R resistance derived gene sets were significantly more biased to patients with shorter survival. From the most differentially expressed genes, we derived a 17-gene expression signature that identifies ovarian cancer patients with shorter overall survival in three independent datasets. We propose that the use of cisplatin resistant cell lines in 3D spheroid models is a viable approach to gain insight into resistance mechanisms relevant to ovarian tumors in patients. Our data support the emerging concept that ovarian cancers can acquire drug resistance through an epithelial-to-mesenchymal transition.

  2. Mechanisms of resistance to linalool in Salmonella Senftenberg and their role in survival on basil.

    Science.gov (United States)

    Kalily, Emmanuel; Hollander, Amit; Korin, Ben; Cymerman, Itamar; Yaron, Sima

    2016-11-01

    Fresh produce contaminated with human pathogens raises vital and ecological questions about bacterial survival strategies. Such occurrence was basil harboring Salmonella enterica serovar Senftenberg that caused an outbreak in 2007. This host was unanticipated due to its production of antibacterial substances, including linalool. We show that linalool perforates bacterial membranes, resulting in increased permeability and leakage of vital molecules. It also inhibits cell motility and causes bacterial aggregation. Linalool-resistance was investigated by identification and characterization of S. Senftenberg mutants that perform altered resistance. Resistance mechanisms include selective permeability, regulated efflux/influx and chemotaxis-controlled motility. Moreover, survival of S. Senftenberg on basil leaves was substantially affected by McpL, a putative chemotaxis-related receptor, and RfaG, a component of the lipopolysaccharide production pathway, both have a role in resistance to linalool. Results reveal that adaptation to linalool occurs in nature by concurrent mechanisms. This adaption raises concerns about pathogens adaptation to new hosts including antimicrobial-compound-producing plants. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures

    OpenAIRE

    Shim, Hye Won; Yang, Byoung-Eun

    2015-01-01

    PURPOSE To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos? implants. MATERIALS AND METHODS This was a retrospective clinical study that analyzed 450 single Ankylos? implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to ag...

  4. Corrosion resistance of zirconium: general mechanisms, behaviour in nitric acid

    International Nuclear Information System (INIS)

    Pinard Legry, G.

    1990-01-01

    Corrosion resistance of zirconium results from the strong affinity of this metal for oxygen; as a result a thin protective oxide film is spontaneously formed in air or aqueous media, its thickness and properties depending on the physicochemical conditions at the interface. This film passivates the underlying metal but obviously if the passive film is partially or completely removed, localised or generalised corrosion phenomena will occur. In nitric acid, this depassivation may be chemical (fluorides) or mechanical (straining, creep, fretting). In these cases it is useful to determine the physicochemical conditions (concentration, temperature, potential, stress) which will have to be observed to use safely zirconium and its alloys in nitric acid solutions [fr

  5. Amino acid secondary transporters: toward a common transport mechanism.

    Science.gov (United States)

    Schweikhard, Eva S; Ziegler, Christine M

    2012-01-01

    Solute carriers (SLC) that transport amino acids are key players in health and diseases in humans. Their prokaryotic relatives are often involved in essential physiological processes in microorganisms, e.g. in homeostasis and acidic/osmotic stress response. High-resolution X-ray structures of the sequence-unrelated amino acid transporters unraveled a striking structural similarity between carriers, which were formerly assigned to different families. The highly conserved fold is characterized by two inverted structural repeats of five transmembrane helices each and indicates common mechanistic transport concepts if not an evolutionary link among a large number of amino acid transporters. Therefore, these transporters are classified now into the structural amino acid-polyamine-organocation superfamily (APCS). The APCS includes among others the mammalian SLC6 transporters and the heterodimeric SLC7/SLC3 transporters. However, it has to be noted that the APCS is not limited entirely to amino acid transporters but contains also transporters for, e.g. amino acid derivatives and sugars. For instance, the betaine-choline-carnitine transporter family of bacterial activity-regulated Na(+)- and H(+)-coupled symporters for glycine betaine and choline is also part of this second largest structural superfamily. The APCS fold provides different possibilities to transport the same amino acid. Arginine can be transported by an H(+)-coupled symport or by antiport mechanism in exchange against agmatine for example. The convergence of the mechanistic concept of transport under comparable physiological conditions allows speculating if structurally unexplored amino acid transporters, e.g. the members of the SLC36 and SLC38 family, belong to the APCS, too. In the kidney, which is an organ that depends critically on the regulated amino acid transport, these different SLC transporters have to work together to account for proper function. Here, we will summarize the basic concepts of Na

  6. Single sample expression-anchored mechanisms predict survival in head and neck cancer.

    Directory of Open Access Journals (Sweden)

    Xinan Yang

    2012-01-01

    Full Text Available Gene expression signatures that are predictive of therapeutic response or prognosis are increasingly useful in clinical care; however, mechanistic (and intuitive interpretation of expression arrays remains an unmet challenge. Additionally, there is surprisingly little gene overlap among distinct clinically validated expression signatures. These "causality challenges" hinder the adoption of signatures as compared to functionally well-characterized single gene biomarkers. To increase the utility of multi-gene signatures in survival studies, we developed a novel approach to generate "personal mechanism signatures" of molecular pathways and functions from gene expression arrays. FAIME, the Functional Analysis of Individual Microarray Expression, computes mechanism scores using rank-weighted gene expression of an individual sample. By comparing head and neck squamous cell carcinoma (HNSCC samples with non-tumor control tissues, the precision and recall of deregulated FAIME-derived mechanisms of pathways and molecular functions are comparable to those produced by conventional cohort-wide methods (e.g. GSEA. The overlap of "Oncogenic FAIME Features of HNSCC" (statistically significant and differentially regulated FAIME-derived genesets representing GO functions or KEGG pathways derived from HNSCC tissue among three distinct HNSCC datasets (pathways:46%, p<0.001 is more significant than the gene overlap (genes:4%. These Oncogenic FAIME Features of HNSCC can accurately discriminate tumors from control tissues in two additional HNSCC datasets (n = 35 and 91, F-accuracy = 100% and 97%, empirical p<0.001, area under the receiver operating characteristic curves = 99% and 92%, and stratify recurrence-free survival in patients from two independent studies (p = 0.0018 and p = 0.032, log-rank. Previous approaches depending on group assignment of individual samples before selecting features or learning a classifier are limited by design to

  7. Mechanisms of acid-base regulation in peritoneal dialysis.

    Science.gov (United States)

    Sow, Amadou; Morelle, Johann; Hautem, Nicolas; Bettoni, Carla; Wagner, Carsten A; Devuyst, Olivier

    2017-11-22

    Peritoneal dialysis (PD) contributes to restore acid-base homeostasis in patients with end-stage renal disease. The transport pathways for buffers and carbon dioxide (CO2) across the peritoneal membrane remain poorly understood. Combining well-established PD protocols, whole-body plethysmography and renal function studies in mice, we investigated molecular mechanisms of acid-base regulation in PD, including the potential role of the water channel aquaporin-1 (AQP1). After instillation in peritoneal cavity, the pH of acidic dialysis solutions increased within minutes to rapidly equilibrate with blood pH, whereas the neutral pH of biocompatible solutions remained constant. Predictions from the three-pore model of peritoneal transport suggested that local production of HCO3- accounts at least in part for the changes in intraperitoneal pH observed with acidic solutions. Carbonic anhydrase (CA) isoforms were evidenced in the peritoneal membrane and their inhibition with acetazolamide significantly decreased local production of HCO3- and delayed changes in intraperitoneal pH. On the contrary, genetic deletion of AQP1 had no effect on peritoneal transport of buffers and diffusion of CO2. Besides intraperitoneal modifications, the use of acidic dialysis solutions enhanced acid excretion both at pulmonary and renal levels. These findings suggest that changes in intraperitoneal pH during PD are mediated by bidirectional buffer transport and by CA-mediated production of HCO3- in the membrane. The use of acidic solutions enhances acid excretion through respiratory and renal responses, which should be considered in patients with renal failure. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  8. Antiatherogenic effects of n-3 fatty acids - evidence and mechanisms

    Directory of Open Access Journals (Sweden)

    Antonella Zampolli

    2006-12-01

    Full Text Available N-3 (omega-3 (polyunsaturated fatty acids are thought to display a variety of beneficial effects for human health. Clues to the occurrence of cardiovascular protective effects have been, however, the spur for the first biomedical interest in these compounds, and are the best documented. Historically, the epidemiologic association between dietary consumption of n-3 fatty acids and cardiovascular protection was first suggested by Bang and Dyerberg, who identified the high consumption of fish, and therefore, of fish oil-derived n-3 fatty acids, as the likely explanation for the strikingly low rate of coronary heart disease events reported in the Inuit population. Since their initial reports, research has proceeded in parallel to provide further evidence for their cardioprotection and to understand underlying mechanisms. Decreased atherogenesis is currently thought to be a part of the cardiovascular protection by n-3 fatty acids. This article summarizes the evidence for such a claim and the mechanisms putatively involved. (Heart International 2006; 3-4: 141-54

  9. The survival mechanism of Home Industries (UMKM of poor families after a disaster

    Directory of Open Access Journals (Sweden)

    Udji Asiyah

    2018-03-01

    Full Text Available The numerous forms of dependent UMKMs actors and their financial deficit, as well as the threat of poverty, should be prevented by using the substitute institutions that will be able to fulfill the needs of UMKMs in terms of capital, fulfilment of raw materials and marketing activities. The flood of Bengawan Solo River is often served as an annual problem faced by the UMKM in the disaster prone areas. The aim of this research is to formulate contextual intervention policies and programs, especially for community empowerment of home industries (UMKM actors who are the disasters victims. This research used quantitative method. The data collection technique is interview with the total number of respondents 100 poor families who rely on their daily lives from business industries (UMKM and in-depth interview to the ten selected informants. Among the UMKM actors who are looking for capital loans for new business start-up, seems to be the most common way to survive. When the prospect to expand the business is believed to be still there, then a respondent will try to rebuild his business from the bottom. However, when they feel there is no opportunity to restart their businesses, then the mechanism is trying to find another job to survive the survival of his family. The efforts to empower UMKM in disaster prone areas cannot be done by relying on a charitable programs and activities, but most importantly is how to awaken, give opportunities and empower UMKM actors in the real sense.

  10. Mechanism of antiinflammatory actions of curcumine and boswellic acids.

    Science.gov (United States)

    Ammon, H P; Safayhi, H; Mack, T; Sabieraj, J

    1993-03-01

    Curcumine from Curcuma longa and the gum resin of Boswellia serrata, which were demonstrated to act as anti-inflammatories in in vivo animal models, were studied in a set of in vitro experiments in order to elucidate the mechanism of their beneficial effects. Curcumine inhibited the 5-lipoxygenase activity in rat peritoneal neutrophils as well as the 12-lipoxygenase and the cyclooxygenase activities in human platelets. In a cell free peroxidation system curcumine exerted strong antioxidative activity. Thus, its effects on the dioxygenases are probably due to its reducing capacity. Boswellic acids were isolated from the gum resin of Boswellia serrata and identified as the active principles. Boswellic acids inhibited the leukotriene synthesis via 5-lipoxygenase, but did not affect the 12-lipoxygenase and the cyclooxygenase activities. Additionally, boswellic acids did not impair the peroxidation of arachidonic acid by iron and ascorbate. The data suggest that boswellic acids are specific, non-redox inhibitors of leukotriene synthesis either interacting directly with 5-lipoxygenase or blocking its translocation.

  11. Queen survival and oxalic acid residues in sugar stores after summer application against Varroa destructor in honey bees (Apis mellifera)

    NARCIS (Netherlands)

    Cornelissen, B.; Donders, J.N.L.C.; Stratum, van P.; Blacquière, T.; Dooremalen, van C.

    2012-01-01

    Methods using oxalic acid (OA) to control Varroa destructor in honey bee (Apis mellifera) colonies are widely applied. In this study, the effects of an OA spray application in early summer on the survival of young and old queens, and on OA residues in sugar stores were investigated. A questionnaire

  12. Survival mechanisms of vertebrate ectotherms at subfreezing temperatures: applications in cryomedicine.

    Science.gov (United States)

    Costanzo, J P; Lee, R E; DeVries, A L; Wang, T; Layne, J R

    1995-03-01

    Various marine fishes, amphibians, and reptiles survive at temperatures several degrees below the freezing point of their body fluids by virtue of adaptive mechanisms that promote freeze avoidance or freeze tolerance. Freezing is avoided by a colligative depression of the blood freezing point, supercooling of the body fluids, or the biosynthesis of unique antifreeze proteins that inhibit the propagation of ice within body fluids. Conversely, freeze tolerance is an adaptation for the survival of tissue freezing under ecologically relevant thermal and temporal conditions that is conferred by the biosynthesis of permeating carbohydrate cryoprotectants and an extensive dehydration of tissues and organs. Such cryoprotective responses, invoked by the onset of freezing, mitigate the osmotic stress associated with freeze-concentration of cytoplasm, attendant metabolic perturbations, and physical damage. Cryomedical research has historically relied on mammalian models for experimentation even though endotherms do not naturally experience subfreezing temperatures. Some vertebrate ectotherms have "solved" not only the problem of freezing individual tissues and organs, but also that of simultaneously freezing all organ systems. An emerging paradigm in cryomedicine is the application of principles governing natural cold hardiness to the development of protocols for the cryopreservation of mammalian tissues and organs.

  13. Selective stimulation of excitatory amino acid receptor subtypes and the survival of cerebellar granule cells in culture: effect of kainic acid

    DEFF Research Database (Denmark)

    Balázs, R; Hack, N; Jørgensen, Ole Steen

    1990-01-01

    Our previous studies showed that the survival of cerebellar granule cells in culture is promoted by treatment with N-methyl-D-aspartate. Here we report on the influence of another glutamate analogue, kainic acid, which, in contrast to N-methyl-D-aspartate, is believed to stimulate transmitter rec...

  14. Kinetic studies of Candida parapsilosis phagocytosis by macrophages and detection of intracellular survival mechanisms

    Directory of Open Access Journals (Sweden)

    Renata eToth

    2014-11-01

    Full Text Available Even though the number of Candida infections due to non-albicans species like C. parapsilosis has been increasing, little is known about their pathomechanisms. Certain aspects of C. parapsilosis and host interactions have already been investigated; however we lack information about the innate cellular responses towards this species. The aim of our project was to dissect and compare the phagocytosis of C. parapsilosis to C. albicans and to another Candida species C. glabrata by murine and human macrophages by live cell video microscopy. We broke down the phagocytic process into three stages: macrophage migration, engulfment of fungal cells and host cell killing after the uptake. Our results showed increased macrophage migration towards C. parapsilosis and we observed differences during the engulfment processes when comparing the three species. The engulfment time of C. parapsilosis was comparable to that of C. albicans regardless of the pseudohypha length and spatial orientation relative to phagocytes, while the rate of host cell killing and the overall uptake regarding C. parapsilosis showed similarities mainly with C. glabrata. Furthermore, we observed difference between human and murine phagocytes in the uptake of C. parapsilosis. UV-treatment of fungal cells had varied effects on phagocytosis dependent upon which Candida strain was used. Besides statistical analysis, live cell imaging videos showed that this species similarly to the other two also has the ability to survive in host cells via the following mechanisms: yeast replication, and pseudohypha growth inside of phagocytes, exocytosis of fungal cells and also abortion of host cell mitosis following the uptake. According to our knowledge this is the first study that provides a thorough examination of C. parapsilosis phagocytosis and reports intracellular survival mechanisms associated with this species.

  15. Effect of mechanical site preparation treatments on oak survival in a retired field afforestation effort -- first-year results

    Science.gov (United States)

    Andrew B. Self; Andrew W. Ezell; Damon B. Hollis; Derek. Alkire

    2011-01-01

    Mechanical site preparation is frequently proposed to alleviate poor soil conditions when afforesting retired agricultural fields. Without management of soil problems, oak seedlings planted in these areas may exhibit poor survival. While mechanical site preparation methods currently employed in hardwood afforestation are proven, there is a substantial void in research...

  16. Molecular mechanism of free fatty acids-induced insulin resistance

    Directory of Open Access Journals (Sweden)

    Hui-zhe CAO

    2017-02-01

    Full Text Available Insulin resistance (IR is a complex metabolic disorder related to several diseases including type 2 diabetes (T2DM, hypertension and dyslipidemia. These diseases are all independent risk factors for cardiovascular disease. Lipid metabolism disorder has toxic effects on cells and may cause or aggravate IR in performance of elevated plasma levels of triglyceride (TG and free fatty acids (FFA, the last one is an independent risk factor for IR. It has been clear that FFA may induce IR by endoplasmic reticulum (ER stress, oxidative stress, apoptosis and inflammation, although the specific mechanisms remained unknown. The present paper summarizes the related molecules involved in the pathogenic process of IR and its mechanism, might provide a theoretical basis for the molecular mechanism of IR caused by FFA, and therapeutic reference for clinical treatment of IR and prevention of T2DM. DOI: 10.11855/j.issn.0577-7402.2017.01.16

  17. [Mazindol effects on the salivary and gastric acid secretory mechanisms].

    Science.gov (United States)

    Shiraishi, T

    1984-02-01

    The effects of mazindol on the salivary secretion of dogs was investigated. Mazindol (2 mg/kg, i.v.) decreased the volume and pressure of salivary secretion induced by either chemical (carpronium) stimulation or electrical nerve stimulation. It also reduced spontaneous salivary secretion. Secretion velocity in the mazindol treated group was significantly less than in the physiological saline administered control group at 4 to 6 min after injection. Saline and mazindol produced no significance differences in Na+, Cl- or K+ concentrations in the saliva or serum. Thus mazindol inhibition of salivary secretion was not caused by ion transport. The existence of some other inhibitory mechanism is suggested. The effects of mazindol on the peripheral and central control of gastric acid secretion was also investigated in rats. Gastric acid secretion induced by direct application of cholinergic agents on oxyntic cells was not affected by mazindol. Gastric acid secretion induced by insulin and/or 2-DG, on the other hand, was markedly inhibited by intra-hypothalamic injection or systemic (i.v.) injections of mazindol. Electro-osmotic mazindol mimicked the effects of glucose in the lateral (inhibition) and ventromedial (excitation) hypothalamus. The results suggest that the inhibitory effects of mazindol on salivary secretion may be through the hypothalamic feeding control centers. Mazindol also directly affected gastric acid secretory neurons in the lateral hypothalamus. It might thus be expected to be effective in the treatment of obesity.

  18. Promoting extracellular matrix remodeling via ascorbic acid enhances the survival of primary ovarian follicles encapsulated in alginate hydrogels.

    Science.gov (United States)

    Tagler, David; Makanji, Yogeshwar; Tu, Tao; Bernabé, Beatriz Peñalver; Lee, Raymond; Zhu, Jie; Kniazeva, Ekaterina; Hornick, Jessica E; Woodruff, Teresa K; Shea, Lonnie D

    2014-07-01

    The in vitro growth of ovarian follicles is an emerging technology for fertility preservation. Various strategies support the culture of secondary and multilayer follicles from various species including mice, non-human primate, and human; however, the culture of early stage (primary and primordial) follicles, which are more abundant in the ovary and survive cryopreservation, has been limited. Hydrogel-encapsulating follicle culture systems that employed feeder cells, such as mouse embryonic fibroblasts (MEFs), stimulated the growth of primary follicles (70-80 µm); yet, survival was low and smaller follicles (ascorbic acid based on its role in extracellular matrix (ECM) deposition/remodeling for other applications. The selection of ascorbic acid was further supported by a microarray analysis that suggested a decrease in mRNA levels of enzymes within the ascorbate pathway between primordial, primary, and secondary follicles. The supplementation of ascorbic acid (50 µg/mL) significantly enhanced the survival of primary follicles (<80 µm) cultured in alginate hydrogels, which coincided with improved structural integrity. Follicles developed antral cavities and increased to diameters exceeding 250 µm. Consistent with improved structural integrity, the gene/protein expression of ECM and cell adhesion molecules was significantly changed. This research supports the notion that modifying the culture environment (medium components) can substantially enhance the survival and growth of early stage follicles. © 2013 Wiley Periodicals, Inc.

  19. Specific Monoclonal Antibody Overcomes the Salmonella enterica Serovar Typhimurium's Adaptive Mechanisms of Intramacrophage Survival and Replication.

    Directory of Open Access Journals (Sweden)

    Swarmistha Devi Aribam

    Full Text Available Salmonella-specific antibodies play an important role in host immunity; however, the mechanisms of Salmonella clearance by pathogen-specific antibodies remain to be completely elucidated since previous studies on antibody-mediated protection have yielded inconsistent results. These inconsistencies are at least partially attributable to the use of polyclonal antibodies against Salmonella antigens. Here, we developed a new monoclonal antibody (mAb-449 and identified its related immunogen that protected BALB/c mice from infection with Salmonella enterica serovar Typhimurium. In addition, these data indicate that the mAb-449 immunogen is likely a major protective antigen. Using in vitro infection studies, we also analyzed the mechanism by which mAb-449 conferred host protection. Notably, macrophages infected with mAb-449-treated S. Typhimurium showed enhanced pathogen uptake compared to counterparts infected with control IgG-treated bacteria. Moreover, these macrophages produced elevated levels of pro-inflammatory cytokine TNFα and nitric oxide, indicating that mAb-449 enhanced macrophage activation. Finally, the number of intracellular bacteria in mAb-449-activated macrophages decreased considerably, while the opposite was found in IgG-treated controls. Based on these findings, we suggest that, although S. Typhimurium has the potential to survive and replicate within macrophages, host production of a specific antibody can effectively mediate macrophage activation for clearance of intracellular bacteria.

  20. Thermal and mechanical properties of fatty acid starch esters.

    Science.gov (United States)

    Winkler, H; Vorwerg, W; Rihm, R

    2014-02-15

    The current study examined thermal and mechanical properties of fatty acid starch esters (FASEs). All highly soluble esters were obtained by the sustainable, homogeneous transesterification of fatty acid vinyl esters in dimethylsulfoxide (DMSO). Casted films of products with a degree of substitution (DS) of 1.40-1.73 were compared with highly substituted ones (DS 2.20-2.63). All films were free of any plasticizer additives. Hydrophobic surfaces were characterized by contact angle measurements. Dynamic scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) revealed thermal transitions (T(g), T(m)) which were influenced by the internal plasticizing effect of the ester groups. Thermal gravimetric analysis (TGA) measurements showed the increased thermal stability toward native starch. Tensile tests revealed the decreasing strength and stiffness of the products with increasing ester-group chain length while the elongation increased up to the ester group laurate and after that decreased. Esters of the longest fatty acids, palmitate and stearate turned out to be brittle materials due to super molecular structures of the ester chains such as confirmed by X-ray. Summarized products with a DS 1.40-1.73 featured more "starch-like" properties with tensile strength up to outstanding 43 MPa, while products with a DS >2 behaved more "oil-like". Both classes of esters should be tested as a serious alternative to commercial starch blends and petrol-based plastics. The term Cnumber is attributed to the number of total C-Atoms of the fatty acid (e.g. C6=Hexanoate). Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. The Kinetics and Mechanism for the Oxidation of Nicotinic Acid by Peroxomonosulfate in Acidic Aqueous Medium

    International Nuclear Information System (INIS)

    Agrawal, Anju; Sailani, Riya; Gupta, Beena; Khandelwal, C. L.; Sharma, P. D.

    2012-01-01

    The kinetics of oxidation of nicotinic acid by peroxomonosulfate (PMS) has been studied in acetate buffers. Stoichiometry of the reaction corresponds to the reaction of one mole of the oxidant with a mole of nicotinic acid. N→O product has been confirmed both by UV visible and IR spectroscopy. The reaction is second order viz. first order with respect to each reactant. Activation parameters have also been evaluated. A plausible reaction mechanism is mentioned and the derived kinetic rate law accounts for experimental observations

  2. VILIP-1 downregulation in non-small cell lung carcinomas: mechanisms and prediction of survival.

    Directory of Open Access Journals (Sweden)

    Jian Fu

    2008-02-01

    Full Text Available VILIP-1, a member of the neuronal Ca++ sensor protein family, acts as a tumor suppressor gene in an experimental animal model by inhibiting cell proliferation, adhesion and invasiveness of squamous cell carcinoma cells. Western Blot analysis of human tumor cells showed that VILIP-1 expression was undetectable in several types of human tumor cells, including 11 out of 12 non-small cell lung carcinoma (NSCLC cell lines. The down-regulation of VILIP-1 was due to loss of VILIP-1 mRNA transcripts. Rearrangements, large gene deletions or mutations were not found. Hypermethylation of the VILIP-1 promoter played an important role in gene silencing. In most VILIP-1-silent cells the VILIP-1 promoter was methylated. In vitro methylation of the VILIP-1 promoter reduced its activity in a promoter-reporter assay. Transcriptional activity of endogenous VILIP-1 promoter was recovered by treatment with 5'-aza-2'-deoxycytidine (5'-Aza-dC. Trichostatin A (TSA, a histone deacetylase inhibitor, potently induced VILIP-1 expression, indicating that histone deacetylation is an additional mechanism of VILIP-1 silencing. TSA increased histone H3 and H4 acetylation in the region of the VILIP-1 promoter. Furthermore, statistical analysis of expression and promoter methylation (n = 150 primary NSCLC samples showed a significant relationship between promoter methylation and protein expression downregulation as well as between survival and decreased or absent VILIP-1 expression in lung cancer tissues (p<0.0001. VILIP-1 expression is silenced by promoter hypermethylation and histone deacetylation in aggressive NSCLC cell lines and primary tumors and its clinical evaluation could have a role as a predictor of short-term survival in lung cancer patients.

  3. Temperature dependence of poly(lactic acid) mechanical properties

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Guo, Huilong; Li, Jingqing

    2016-01-01

    The mechanical properties of polymers are not only determined by their structures, but also related to the temperature field in which they are located. The yield behaviors, Young's modulus and structures of injection-molded poly(lactic acid) (PLA) samples after annealing at different temperatures....... For the samples annealed between 80 and 120 oC, a peculiar double yield appears when stretched within 50–60 oC and only the first or the second yield can be found at the lower and higher draw temperatures. The yield strain and yield stress together with Young's modulus were obtained and discussed in terms...

  4. Adiponectin receptor 1 conserves docosahexaenoic acid and promotes photoreceptor cell survival.

    Science.gov (United States)

    Rice, Dennis S; Calandria, Jorgelina M; Gordon, William C; Jun, Bokkyoo; Zhou, Yongdong; Gelfman, Claire M; Li, Songhua; Jin, Minghao; Knott, Eric J; Chang, Bo; Abuin, Alex; Issa, Tawfik; Potter, David; Platt, Kenneth A; Bazan, Nicolas G

    2015-03-04

    The identification of pathways necessary for photoreceptor and retinal pigment epithelium (RPE) function is critical to uncover therapies for blindness. Here we report the discovery of adiponectin receptor 1 (AdipoR1) as a regulator of these cells' functions. Docosahexaenoic acid (DHA) is avidly retained in photoreceptors, while mechanisms controlling DHA uptake and retention are unknown. Thus, we demonstrate that AdipoR1 ablation results in DHA reduction. In situ hybridization reveals photoreceptor and RPE cell AdipoR1 expression, blunted in AdipoR1(-/-) mice. We also find decreased photoreceptor-specific phosphatidylcholine containing very long-chain polyunsaturated fatty acids and severely attenuated electroretinograms. These changes precede progressive photoreceptor degeneration in AdipoR1(-/-) mice. RPE-rich eyecup cultures from AdipoR1(-/-) reveal impaired DHA uptake. AdipoR1 overexpression in RPE cells enhances DHA uptake, whereas AdipoR1 silencing has the opposite effect. These results establish AdipoR1 as a regulatory switch of DHA uptake, retention, conservation and elongation in photoreceptors and RPE, thus preserving photoreceptor cell integrity.

  5. Valproic Acid Use During Radiation Therapy for Glioblastoma Associated With Improved Survival

    International Nuclear Information System (INIS)

    Barker, Christopher A.; Bishop, Andrew J.; Chang, Maria; Beal, Kathryn; Chan, Timothy A.

    2013-01-01

    Purpose: Valproic acid (VA) is an antiepileptic drug (AED) and histone deacetylase (HDAC) inhibitor taken by patients with glioblastoma (GB) to manage seizures, and it can modulate the biologic effects of radiation therapy (RT). We investigated whether VA use during RT for GB was associated with overall survival (OS). Methods and Materials: Medical records of 544 adults with GB were retrospectively reviewed. Analyses were performed to determine the association of Radiation Therapy Oncology Group recursive partitioning analysis (RTOG RPA) class, seizure history, and concurrent temozolomide (TMZ) and AED use during RT with OS. Results: Seizures before the end of RT were noted in 217 (40%) patients, and 403 (74%) were taking an AED during RT; 29 (7%) were taking VA. Median OS in patients taking VA was 16.9 months (vs 13.6 months taking another AED, P=.16). Among patients taking an AED during RT, OS was associated with VA (P=.047; hazard ratio [HR], 0.67; 95% confidence interval [CI], 0.27-1.07), and RTOG RPA class (P<.0001; HR, 1.49; 95% CI, 1.37-1.61). Of the 5 most common AEDs, only VA was associated with OS. Median OS of patients receiving VA and TMZ during RT was 23.9 months (vs 15.2 months for patients taking another AED, P=.26). When the analysis was restricted to patients who received concurrent TMZ, VA use was marginally associated with OS (P=.057; HR, 0.54; 95% CI, −0.09 to 1.17), independently of RTOG RPA class and seizure history. Conclusions: VA use during RT for GB was associated with improved OS, independently of RTOG RPA, seizure history, and concurrent TMZ use. Further studies of treatment that combines HDAC inhibitors and RT are warranted

  6. THE MECHANISM OF FLOTATION ISOLATION FINE-EMULSIFIED FATTY ACIDS

    Directory of Open Access Journals (Sweden)

    V. F. Sazonova

    2015-02-01

    Full Text Available It is positioned, that the flotation mechanism fine-emulsified fatty acids is defined by a sign and value of an electrokinetic potential of fatty acids drops and air bubbles, and also a parity of attractive forces and pushing away between drops and air bubbles which, in turn, are functions pH medium. It is shown, that in the subacidic medium (pH 6 extraction degree makes 97 %, flotation process is described by the kinetic equation of the first order, and interaction of drops and air bubbles is carried out in absence of energy barrier of pushing away between them. At increase in acidity of medium (pH 2 extraction degree decreases to 40 %, order of the kinetic equation changes from the first on the second, and fastening of drops on a surface of air bubbles occurs as a result of distant interaction (in a distant potential minimum on the graph of potential energy of interaction of drops and air bubbles from distances between them.

  7. Mechanisms of triglyceride metabolism in patients with bile acid diarrhea.

    Science.gov (United States)

    Sagar, Nidhi Midhu; McFarlane, Michael; Nwokolo, Chuka; Bardhan, Karna Dev; Arasaradnam, Ramesh Pulendran

    2016-08-14

    Bile acids (BAs) are essential for the absorption of lipids. BA synthesis is inhibited through intestinal farnesoid X receptor (FXR) activity. BA sequestration is known to influence BA metabolism and control serum lipid concentrations. Animal data has demonstrated a regulatory role for the FXR in triglyceride metabolism. FXR inhibits hepatic lipogenesis by inhibiting the expression of sterol regulatory element binding protein 1c via small heterodimer primer activity. Conversely, FXR promotes free fatty acids oxidation by inducing the expression of peroxisome proliferator-activated receptor α. FXR can reduce the expression of microsomal triglyceride transfer protein, which regulates the assembly of very low-density lipoproteins (VLDL). FXR activation in turn promotes the clearance of circulating triglycerides by inducing apolipoprotein C-II, very low-density lipoproteins receptor (VLDL-R) and the expression of Syndecan-1 together with the repression of apolipoprotein C-III, which increases lipoprotein lipase activity. There is currently minimal clinical data on triglyceride metabolism in patients with bile acid diarrhoea (BAD). Emerging data suggests that a third of patients with BAD have hypertriglyceridemia. Further research is required to establish the risk of hypertriglyceridaemia in patients with BAD and elicit the mechanisms behind this, allowing for targeted treatment.

  8. Thrombolytic Therapy for Right-Sided Mechanical Pulmonic and Tricuspid Valves: The Largest Survival Analysis to Date.

    Science.gov (United States)

    Taherkhani, Maryam; Hashemi, Seyed Reza; Hekmat, Manouchehr; Safi, Morteza; Taherkhani, Adineh; Movahed, Mohammad Reza

    2015-12-01

    Data regarding thrombolytic treatment of right-sided mechanical valve thrombosis are almost nonexistent, and all current guidelines arise from very small case series. We retrospectively studied the in-hospital and long-term outcome data of a larger series of patients who had received, from September 2005 through June 2012, thrombolytic therapy for right-sided mechanical pulmonary valve or tricuspid valve thrombosis. We identified 16 patients aged 8-67 years who had undergone thrombolytic therapy for definite thrombotic mechanical valve obstruction in the tricuspid or pulmonary valve position (8 in each position). All study patients except one had subtherapeutic international normalized ratios. The 8 patients with pulmonary mechanical valve thrombosis had a 100% response rate to thrombolytic therapy, and their in-hospital survival rate was also 100%. The 8 patients with tricuspid mechanical valve thrombosis had a 75% response rate to thrombolytic therapy, with an in-hospital survival rate of 87.5%. The one-year survival rate for mechanical valve thrombosis treated with thrombolytic therapy (whether pulmonary or tricuspid) was 87.5%. On the basis of our data, we recommend that thrombolytic therapy remain the first-line therapy for right-sided mechanical valve thrombosis in adults or children-including children with complex congenital heart disease and patients with mechanical pulmonary valve thrombosis. Surgery should be reserved for patients in whom this treatment fails.

  9. Boric acid inhibits embryonic histone deacetylases: A suggested mechanism to explain boric acid-related teratogenicity

    International Nuclear Information System (INIS)

    Di Renzo, Francesca; Cappelletti, Graziella; Broccia, Maria L.; Giavini, Erminio; Menegola, Elena

    2007-01-01

    Histone deacetylases (HDAC) control gene expression by changing histonic as well as non histonic protein conformation. HDAC inhibitors (HDACi) are considered to be among the most promising drugs for epigenetic treatment for cancer. Recently a strict relationship between histone hyperacetylation in specific tissues of mouse embryos exposed to two HDACi (valproic acid and trichostatin A) and specific axial skeleton malformations has been demonstrated. The aim of this study is to verify if boric acid (BA), that induces in rodents malformations similar to those valproic acid and trichostatin A-related, acts through similar mechanisms: HDAC inhibition and histone hyperacetylation. Pregnant mice were treated intraperitoneally with a teratogenic dose of BA (1000 mg/kg, day 8 of gestation). Western blot analysis and immunostaining were performed with anti hyperacetylated histone 4 (H4) antibody on embryos explanted 1, 3 or 4 h after treatment and revealed H4 hyperacetylation at the level of somites. HDAC enzyme assay was performed on embryonic nuclear extracts. A significant HDAC inhibition activity (compatible with a mixed type partial inhibition mechanism) was evident with BA. Kinetic analyses indicate that BA modifies substrate affinity by a factor α = 0.51 and maximum velocity by a factor β = 0.70. This work provides the first evidence for HDAC inhibition by BA and suggests such a molecular mechanism for the induction of BA-related malformations

  10. Improved Survival After the Ross Procedure Compared With Mechanical Aortic Valve Replacement.

    Science.gov (United States)

    Buratto, Edward; Shi, William Y; Wynne, Rochelle; Poh, Chin L; Larobina, Marco; O'Keefe, Michael; Goldblatt, John; Tatoulis, James; Skillington, Peter D

    2018-03-27

    It is unclear whether the Ross procedure offers superior survival compared with mechanical aortic valve replacement (AVR). This study evaluated experience and compared long-term survival between the Ross procedure and mechanical AVR. Between 1992 and 2016, a total of 392 Ross procedures were performed. These were compared with 1,928 isolated mechanical AVRs performed during the same time period as identified using the University of Melbourne and Australia and New Zealand Society of Cardiac and Thoracic Surgeons' Cardiac Surgery Databases. Only patients between 18 and 65 years of age were included. Propensity-score matching was performed for risk adjustment. Ross procedure patients were younger, and had fewer cardiovascular risk factors. The Ross procedure was associated with longer cardiopulmonary bypass and aortic cross-clamp times. Thirty-day mortality was similar (Ross, 0.3%; mechanical, 0.8%; p = 0.5). Ross procedure patients experienced superior unadjusted long-term survival at 20 years (Ross, 95%; mechanical, 68%; p Ross procedure to be associated with a reduced risk of late mortality (hazard ratio: 0.34; 95% confidence internal: 0.17 to 0.67; p Ross procedure patients had superior survival at 20 years (Ross, 94%; mechanical, 84%; p = 0.018). In this Australian, propensity-score matched study, the Ross procedure was associated with better long-term survival compared with mechanical AVR. In younger patients, with a long life expectancy, the Ross procedure should be considered in centers with sufficient expertise. Crown Copyright © 2018. Published by Elsevier Inc. All rights reserved.

  11. Mechanisms of neptunium redox reactions in nitric acid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Sayandev; Bryan, Samuel A.; Casella, Amanda J.; Peterson, James M.; Levitskaia, Tatiana G.

    2017-01-01

    First transuranium element neptunium (Np) exhibits complicated behavior in acidic solutions because it can adopt wide range of oxidation states typically from +3 to +6 and coordinate large variety of ligands. In particular, accurate determination of Np redox potentials in nitric acid solutions is challenging due to overlapping chemical and electrochemical reactions leading to significant experimental uncertainties. Furthermore, over past decades spectrophotometry has been extensively applied to identify and characterize Np solution species in different oxidation states. However, relevant spectral database of Np in nitric acid solutions that can serve for the reference purposes has yet to be established due to the experimental difficulty to isolate and stabilize Np species in pure oxidation states without compromising solution optical properties. This work demonstrates that combination of voltammetry and controlled-potential in situ thin-layer spectropotentiometry overcomes these challenges so that Np species in pure +3, +4, +5, or +6 oxidation states were electrochemically generated in the systematically varied 0.1 – 5 M nitric acid solutions, and corresponding vis-NIR spectral signatures were obtained. In situ optical monitoring of the interconversion between adjacent Np oxidation states resulted in elucidation of the mechanisms of the involved redox reactions, in-depth understanding of the relative stability of the Np oxidation states, and allowed benchmarking of the redox potentials of the NpO22+/NpO2+, NpO2+/Np4+ and Np4+/Np3+ couples. Notably, the NpO2+/Np4+ couple was distinguished from the proximal Np4+/Np3+ process overcoming previous concerns and challenges encountered in accurate determination of the respective potentials.

  12. A new regulatory mechanism for bacterial lipoic acid synthesis.

    Science.gov (United States)

    Zhang, Huimin; Luo, Qixia; Gao, Haichun; Feng, Youjun

    2015-01-22

    Lipoic acid, an essential enzyme cofactor, is required in three domains of life. In the past 60 years since its discovery, most of the pathway for lipoic acid synthesis and metabolism has been elucidated. However, genetic control of lipoic acid synthesis remains unclear. Here, we report integrative evidence that bacterial cAMP-dependent signaling is linked to lipoic acid synthesis in Shewanella species, the certain of unique marine-borne bacteria with special ability of metal reduction. Physiological requirement of protein lipoylation in γ-proteobacteria including Shewanella oneidensis was detected using Western blotting with rabbit anti-lipoyl protein primary antibody. The two genes (lipB and lipA) encoding lipoic acid synthesis pathway were proved to be organized into an operon lipBA in Shewanella, and the promoter was mapped. Electrophoretic mobility shift assays confirmed that the putative CRP-recognizable site (AAGTGTGATCTATCTTACATTT) binds to cAMP-CRP protein with origins of both Escherichia coli and Shewanella. The native lipBA promoter of Shewanella was fused to a LacZ reporter gene to create a chromosome lipBA-lacZ transcriptional fusion in E. coli and S. oneidensis, allowing us to directly assay its expression level by β-galactosidase activity. As anticipated, the removal of E. coli crp gene gave above fourfold increment of lipBA promoter-driven β-gal expression. The similar scenario was confirmed by both the real-time quantitative PCR and the LacZ transcriptional fusion in the crp mutant of Shewanella. Furthermore, the glucose effect on the lipBA expression of Shewanella was evaluated in the alternative microorganism E. coli. As anticipated, an addition of glucose into media effectively induces the transcriptional level of Shewanella lipBA in that the lowered cAMP level relieves the repression of lipBA by cAMP-CRP complex. Therefore, our finding might represent a first paradigm mechanism for genetic control of bacterial lipoic acid synthesis. © 2015

  13. Drying of micro-encapsulated lactic acid bacteria — Effects of trehalose and immobilization on cell survival and release properties

    Science.gov (United States)

    Li, Xiaoyan; Chen, Xiguang

    2009-03-01

    Lactic acid bacteria (LAB) were encapsulated with alginate, gelatin and trehalose additives by the extrusion method and dried at 4 °C. The microcapsules were generally spherical and had a wrinkled surface with a size of 1.7 mm ± 0.2 mm. Trehalose as a carbohydrate source in the culture medium could reduce acid production and performed no function in the positive proliferation of LAB. Using trehalose as a carbohydrate source and protective medium simultaneously had a benefit in the protection of LAB cells during the storage at 4 °C. The density of live LAB cells could be 107 CFU g-1 after 8 weeks of storage. Cells of LAB could be continuously released from the capsules from the acidic (pH 1.2) to neutral conditions (pH 6.8). The release amounts and proliferation speeds of LAB cells in neutral medium were much larger and faster than those in acidic conditions. Additionally, immobilization of LAB could improve the survival of cells when they were exposed to acidic medium (pH 1.2) with a survival rate of 76 %.

  14. In-Situ Survival Mechanisms of U and Tc Reducing Bacteria in Contaminated Sediments. Final Report

    International Nuclear Information System (INIS)

    Lee Krumholz Jimmy Ballard

    2005-01-01

    The proposed effort will identify genes and ultimately physiological mechanisms and pathways that are expressed under in situ conditions and are critical to functioning of aquifer dwelling anaerobic bacteria living in contaminated systems. The main objectives are: (1) Determine which Metal-reducer specific genes are important for activities in normal and contaminated subsurface sediment. To achieve these goals, we have generated a library of chromosomal mutants. These are introduced into contaminated sediments, incubated, allowed to grow, and then reisolated. A negative selection process allows us to determine which mutants have been selected against in sediments and thereby identify genes required for survival in subsurface sediments. (2) Delineate the function of these genes through GeneBank and Clusters of Orthologous Groups (COGs) comparisons and analyze other sediment microorganisms to determine if similar genes are present in these populations. After determining the sequence of the genes identified through the previous objectives, we delineate the role of those specific genes in the physiology of G20, MR-1 and perhaps other microorganisms. (3) Determine the loss in function of a select group of mutants. Cells with mutations in known genes with testable functions are assayed for the loss of that function if specific assays are available. Mutants with unknown loss of function and other mutants are run through a series of tests including motility, attachment, and rate of sulfate or iron reduction. These tests allow us to categorize mutants for subsequent more detailed study

  15. Tillage Reduces Survival of Grape Berry Moth (Lepidoptera: Tortricidae), via Burial Rather Than Mechanical Injury.

    Science.gov (United States)

    Matlock, Jason M; Isaacs, Rufus; Grieshop, Matthew

    2017-02-01

    The grape berry moth, Paralobesia viteana (Clemens), is a key pest of vineyards in eastern North America that overwinters as pupae in leaf litter on the vineyard floor. This presents an opportunity for tillage to disturb and bury the pupae, providing a potential nonchemical approach to control of this pest. Using a Lilleston-style rotary cultivator, we determined the distribution of pupae within the soil profile after single tillage passes, measured the type and severity of damage inflicted on pupae, and investigated how these effects on pupae influenced their survival. Survivorship of pupae recovered from the vineyard immediately after tillage and held until emergence was not significantly different from those recovered from an untilled control area, indicating little effect of mechanical damage on this pest. However, a single pass of the tillage implement buried three-quarters of pupae under at least 1 cm of soil. A laboratory experiment to recreate these conditions resulted in significant increase in mortality when pupae were buried in more than 1 cm of sand. We conclude that 1) interference with adult emergence of diapausing pupae via burial is the primary mechanism by which tillage controls grape berry moth, and 2) efforts to optimize the impact of tillage on grape berry moth populations should focus on maximizing the number of pupae buried. We discuss the potential integration of tillage into different vineyard management systems to enhance pest management. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Molecular mechanism of flocculation self-recognition in yeast and its role in mating and survival

    Data.gov (United States)

    National Aeronautics and Space Administration — Saccharomyces cerevisiae flocculation occurs when fermentable sugars are limiting and is therefore considered as a way to enhance the survival chance of...

  17. Genomic resequencing combined with quantitative proteomic analyses elucidate the survival mechanisms of Lactobacillus plantarum P-8 in a long-term glucose-limited experiment.

    Science.gov (United States)

    He, Qiuwen; Cao, Chenxia; Hui, Wenyan; Yu, Jie; Zhang, Heping; Zhang, Wenyi

    2018-03-30

    Lactobacillus plantarum, commonly isolated from plant material, is widely used to produce various types of fermented foods. However, nutrient-limiting conditions are often encountered during industrial applications. The present study aimed to investigate the response of L. plantarum P-8 to glucose-limited conditions in a long-term experiment. Genotypic and proteomic changes in L. plantarum P-8 were monitored over 3 years in glucose-limited and glucose-normal media using whole-genome resequencing and tandem mass tag-based quantitative proteomic analysis. Results showed that L. plantarum employed numerous survival mechanisms, including alteration of the cell envelope, activation of the PTS system, accumulation and consumption of amino acids, increase in the metabolism of carbohydrates (via glycolysis, citric acid cycle, and pyruvate metabolism), and increase in the production of ATP in response to glucose starvation. This study demonstrates the feasibility of experimental evolution of L. plantarum P-8, while whole-genome resequencing of adapted isolates provided clues toward bacterial functions involved and a deeper mechanistic understanding of the adaptive response of L. plantarum to glucose-limited conditions. We have conducted a 3-year experiment monitoring genotypic and proteomic changes in Lactobacillus plantarum P-8 in glucose-limited and glucose-normal media. Whole-genome resequencing and tandem mass tag-based quantitative proteomics were performed for analyzing genomic evolution of L. plantarum P-8 in glucose-limited and glucose-normal conditions. In addition, differential expressed proteins in all generations between these two conditions were identified and functions of these proteins specific to L group were predicted. L. plantarum employed numerous survival mechanisms, including alteration of the cell envelope, activation of the PTS system, accumulation and consumption of amino acids, increase in the metabolism of carbohydrates (glycolysis, citric acid

  18. Restriction endonuclease triggered bacterial apoptosis as a mechanism for long time survival.

    Science.gov (United States)

    Nagamalleswari, Easa; Rao, Sandhya; Vasu, Kommireddy; Nagaraja, Valakunja

    2017-08-21

    Programmed cell death (PCD) under certain conditions is one of the features of bacterial altruism. Given the bacterial diversity and varied life style, different PCD mechanisms must be operational that remain largely unexplored. We describe restriction endonuclease (REase) mediated cell death by an apoptotic pathway, beneficial for isogenic bacterial communities. Cell death is pronounced in stationary phase and when the enzyme exhibits promiscuous DNA cleavage activity. We have elucidated the molecular mechanism of REase mediated cell killing and demonstrate that released nutrients from dying cells support the growth of the remaining cells in the population. These findings illustrate a new intracellular moonlighting role for REases which are otherwise established host defence arsenals. REase induced PCD appears to be a cellular design to replenish nutrients for cells undergoing starvation stress and the phenomenon could be wide spread in bacteria, given the abundance of restriction-modification (R-M) systems in the microbial population. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  19. Kinetics and mechanism of the oxidation of some -hydroxy acids ...

    Indian Academy of Sciences (India)

    The oxidation of lactic acid, mandelic acid and ten monosubstituted mandelic acids by hexamethylenetetramine-bromine (HABR) in glacial acetic acid, leads to the formation of the corresponding oxoacid. The reaction is first order with respect to each of the hydroxy acids and HABR. It is proposed that HABR itself is the ...

  20. Further investigation on boric acid catalytic graphitization of polyacrylonitrile carbon fibers: Mechanism and mechanical properties

    International Nuclear Information System (INIS)

    Wen, Ya; Lu, Yonggen; Xiao, Hao; Qin, Xianying

    2012-01-01

    Highlights: ► The modulus of carbon fiber was improved by boric acid at the temperature range of 1500–2900 °C. ► 2300 °C is a key temperature degree from which the boron began to benefit fiber strength. ► The fiber strength was affected by the boron reaction and related to the boron states. -- Abstract: Catalytic graphitization of polyacrylonitrile based carbon fibers by boric acid doping was studied and the dependence of fiber tensile strength on the boron content and temperature was discussed. It was found that there existed a key temperature point for the boron to take effect. When the fibers were modified with 7.0 wt.% boric acid solution, with increasing temperature, the tensile strength was lower than that of the unmodified ones below 2300 °C, but a reverse thing happened above 2300 °C. Moreover, when being heated at 2500 °C, the modified fibers showed an increasing tensile modulus and strength with increasing boron content till maximums of 404 GPa and 2.46 GPa, 26% and 16% higher than those of unmodified ones. The mechanical properties of the fibers were affected by the interaction of carbon and boron, and also related with boron states. The decomposition of boron acid and its interaction with carbon brought defects on fiber surface, degrading the mechanical properties below 1300 °C. With further heat treatment, the boron diffused into the fibers and divided into two states: substitutional and interstitial. At a temperature over 2300 °C with an appreciate boron content, the substitutional would be formed predominantly, which removed the structural defects and relaxed the distortions, so as to benefit the mechanical properties.

  1. Acid and low temperature treatments on Salmonella Enteritidis inoculated in pork and its subsequent survival in simulated gastric fluid

    Directory of Open Access Journals (Sweden)

    Simone Quintão Silva

    2016-03-01

    Full Text Available ABSTRACT: The objective of this study was to evaluate the acid resistance of Salmonella enterica serovar Enteritidis (S. Enteritidis in stored pork and in simulated gastric fluid (SGF. A culture of S. Enteritidis was subjected to acid treatment prior to inoculation into pork, stored under refrigeration at frozen temperatures and exposed to SGF. The S. Enteritidis CCS3 and ATCC 13076 strains previously subjected to acid treatment (at pH 4.0-5.0 were inoculated in pork and stored at 4°C and -18°C. Storage at 4ºC did not affect the populations of both S. Enteritidis strains. After 84 days at -18°C, the mean population of both CCS3 and ATCC strains were reduced by 0.8 and 1.5 log cycles, respectively. Prior acid treatment did not enhance the survival of both strains at low temperatures. After acid treatment and low temperature storage, S. Enteritidis ATCC 13076 lost culturability after being exposed to SGF for 10 minutes. In contrast, S. Enteritidis CCS3 was tolerant until three hours of SGF exposure. S. Enteritidis CCS3 submitted to pH 4.0 was more tolerant to SGF exposure than when submitted to pH 4.5, 5.0 and without acid treatment. Therefore, this study indicates that exposure to an acidic and cold environment during processing enhanced the ability of S. Enteritidis to survive in the gastric environment of the human stomach, possibly increasing the risk of a Salmonella infection after consumption of pork.

  2. Mitochonic Acid 5 (MA-5 Facilitates ATP Synthase Oligomerization and Cell Survival in Various Mitochondrial Diseases

    Directory of Open Access Journals (Sweden)

    Tetsuro Matsuhashi

    2017-06-01

    Full Text Available Mitochondrial dysfunction increases oxidative stress and depletes ATP in a variety of disorders. Several antioxidant therapies and drugs affecting mitochondrial biogenesis are undergoing investigation, although not all of them have demonstrated favorable effects in the clinic. We recently reported a therapeutic mitochondrial drug mitochonic acid MA-5 (Tohoku J. Exp. Med., 2015. MA-5 increased ATP, rescued mitochondrial disease fibroblasts and prolonged the life span of the disease model “Mitomouse” (JASN, 2016. To investigate the potential of MA-5 on various mitochondrial diseases, we collected 25 cases of fibroblasts from various genetic mutations and cell protective effect of MA-5 and the ATP producing mechanism was examined. 24 out of the 25 patient fibroblasts (96% were responded to MA-5. Under oxidative stress condition, the GDF-15 was increased and this increase was significantly abrogated by MA-5. The serum GDF-15 elevated in Mitomouse was likewise reduced by MA-5. MA-5 facilitates mitochondrial ATP production and reduces ROS independent of ETC by facilitating ATP synthase oligomerization and supercomplex formation with mitofilin/Mic60. MA-5 reduced mitochondria fragmentation, restores crista shape and dynamics. MA-5 has potential as a drug for the treatment of various mitochondrial diseases. The diagnostic use of GDF-15 will be also useful in a forthcoming MA-5 clinical trial.

  3. Deciphering Molecular Mechanism Underlying Hypolipidemic Activity of Echinocystic Acid

    Directory of Open Access Journals (Sweden)

    Li Han

    2014-01-01

    Full Text Available Our previous study showed that a triterpene mixture, consisting of echinocystic acid (EA and oleanolic acid (OA at a ratio of 4 : 1, dose-dependently ameliorated the hyperlipidemia and atherosclerosis in rabbits fed with high fat/high cholesterol diets. This study was aimed at exploring the mechanisms underlying antihyperlipidemic effect of EA. Molecular docking simulation of EA was performed using Molegro Virtual Docker (version: 4.3.0 to investigate the potential targets related to lipid metabolism. Based on the molecular docking information, isotope labeling method or spectrophotometry was applied to examine the effect of EA on the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA reductase, acyl-CoA:cholesterol acyltransferase (ACAT, and diacylglycerol acyltransferase (DGAT in rat liver microsomes. Our results revealed a strong affinity of EA towards ACAT and DGAT in molecular docking analysis, while low binding affinity existed between EA and HMG-CoA reductase as well as between EA and cholesteryl ester transfer protein. Consistent with the results of molecular docking, in vitro enzyme activity assays showed that EA inhibited ACAT and DGAT, with IC50 values of 103 and 139 μM, respectively, and exhibited no significant effect on HMG-CoA reductase activity. The present findings suggest that EA may exert hypolipidemic effect by inhibiting the activity of ACAT and DGAT.

  4. Molecular mechanics force-field development for amino acid zwitterions.

    Science.gov (United States)

    Kirschner, K N; Lewin, A H; Bowen, J P

    2003-01-15

    Understanding the conformational flexibility of amino acid zwitterions (ZWs) and their associated conformational energies is crucial for predicting their interactions in biological systems. Gas-phase ab initio calculations of ZWs are intractable. Molecular mechanics (MM), on the other hand, is able to handle large systems but lacks the necessary force field parameters to model ZWs. To develop force field parameters that are able to correctly model ZW geometries and energetics we used a novel combinatorial approach: amino acid ZWs were broken down structurally into key functional components, which were parameterized separately. Møller-Plesset second-order perturbation calculations on small carboxylates, on the glycine cation, and on novel hydrogen bonded systems, coupled with available experimental data, were used to generate MM3(2000) ZW parameters (Allinger N. L.; Yuh, Y. H.; Lii, J.-H. J Am Chem Soc 1989, 111, 8551). The MM3 results from this combinatorial approach gave geometries that are in good agreement with neutron diffraction experiments, plus their frequencies and energies appear to be reasonably modeled. Current limitations and future development of MM force fields are discussed briefly. Copyright 2002 Wiley Periodicals, Inc. J Comput Chem 24: 111-128, 2003

  5. Microbial Resistance Mechanisms to the Antibiotic and Phytotoxin Fusaric Acid.

    Science.gov (United States)

    Crutcher, Frankie K; Puckhaber, Lorraine S; Stipanovic, Robert D; Bell, Alois A; Nichols, Robert L; Lawrence, Katheryn S; Liu, Jinggao

    2017-10-01

    Fusaric acid (FA) produced by Fusarium oxysporum plays an important role in disease development in plants, including cotton. This non-specific toxin also has antibiotic effects on microorganisms. Thus, one expects a potential pool of diverse detoxification mechanisms of FA in nature. Bacteria and fungi from soils infested with Fusarium and from laboratory sources were evaluated for their ability to grow in the presence of FA and to alter the structure of FA into less toxic compounds. None of the bacterial strains were able to chemically modify FA. Highly FA-resistant strains were found only in Gram-negative bacteria, mainly in the genus of Pseudomonas. The FA resistance of the Gram-negative bacteria was positively correlated with the number of predicted genes for FA efflux pumps present in the genome. Phylogenetic analysis of predicted FA resistance proteins (FUSC, an inner membrane transporter component of the efflux pump) revealed that FUSC proteins having high sequence identities with the functionally characterized FA resistance protein FusC or Fdt might be the major contributors of FA resistance. In contrast, most fungi converted FA to less toxic compounds regardless of the level of FA resistance they exhibited. Five derivatives were detected, and the detoxification of FA involved either oxidative reactions on the butyl side chain or reductive reactions on the carboxylic acid group. The production of these metabolites from widely different phyla indicates that resistance to FA by altering its structure is highly conserved. A few FA resistant saprophytic or biocontrol strains of fungi were incapable of altering FA, indicating a possible involvement of efflux transporters. Deployment of both efflux and derivatization mechanisms may be a common feature of fungal FA resistance.

  6. Nodulation of cowpeas and survival of cowpeas Rhizobia in acid, aluminum-rich soils. [Vigna unguiculata; Rhizobium

    Energy Technology Data Exchange (ETDEWEB)

    Hartel, P.G.; Whelan, A.M.; Alexander, M.

    1983-01-01

    A study was undertaken to determine whether the reduced nodulation of cowpeas (Vigna unguiculata (L.) Walp) grown in certain acid, Alrich soils resulted from the poor survival of the potentially infective rhizobia. Two strains of Rhizobium capable of nodulating cowpeas were used. The lowest pH for growth in defined liquid medium was 4.2 for one strain and 3.9 for the other. Only the latter was Al tolerant and could grow in a defined liquid medium containing 50 ..mu..M KAl(SO/sub 4/)/sub 2/. The survival of the bacteria and their ability to nodulate cowpeas in three soils were measured after the soils were amended with Ca or Al salts to give pH values ranging from 5.7 to 4.1 and extractable-Al concentrations from < 0.1 to 3.7 cmol(p/sup +/)/kg of soil. Only small differences in survival in 7 or 8 weeks were noted between the two strains. Plants inoculated with the Al-sensitive strain bore significantly fewer nodules in the more acid, Al-rich soils than in the same soils with higher pH values and less extractable Al. No significant reduction in nodule number was evident for plants inoculated with the Al-tolerant strain and grown in the more acid, Al-rich soils compared to cowpeas grown in the same soils with higher pH values and less extractable Al. It is suggested that the Al content of soil is not a major factor in the survival of cowpea rhizobia but that it does have a significant effect on nodulation. 24 references, 3 figures, 2 tables.

  7. Effect of Organic Acids and Marination Ingredients on the Survival of Campylobacter jejuni on Meat

    DEFF Research Database (Denmark)

    Birk, Tina; Grønlund, Anne Christine Jørgensen; Christensen, Bjarke Bak

    2010-01-01

    The aim of this study was to determine whether marination of chicken meat in different food ingredients call be used to reduce populations of Campylobacter jejuni strains, were exposed to different organic acids (tartaric, acetic. lactic, malic, and citric acids) and food marinating ingredients...... at 4 degrees C in broth and on chicken meat. The organic acids (0.5%) reduced populations of C. jejuni broth (chicken juice and brain heart infusion broth) by 4 to 6 1011 units (after 24 h): tartaric acid was the most efficient treatment. Large strain variation was observed among 14 C. jejuni isolates...... inoculated in brain heart infusion broth containing 0.3% tartaric acid. On chicken meat medallions, reductions of C. jejuni were 0.5 to 2 log units when tartaric acid solutions (2, 4, 6, and 10%) were spread onto the meal. Analysis of acidic food ingredient (e.g., vinegar. lemon juice, pomegranate syrup...

  8. Putrescine production via the ornithine decarboxylation pathway improves the acid stress survival of Lactobacillus brevis and is part of a horizontally transferred acid resistance locus.

    Science.gov (United States)

    Romano, Andrea; Ladero, Victor; Alvarez, Miguel A; Lucas, Patrick M

    2014-04-03

    Decarboxylation pathways are widespread among lactic acid bacteria; their physiological role is related to acid resistance through the regulation of the intracellular pH and to the production of metabolic energy via the generation of a proton motive force and its conversion into ATP. These pathways include, among others, biogenic amine (BA) production pathways. BA accumulation in foodstuffs is a health risk; thus, the study of the factors involved in their production is of major concern. The analysis of several lactic acid bacterial strains isolated from different environments, including fermented foods and beverages, revealed that the genes encoding these pathways are clustered on the chromosome, which suggests that these genes are part of a genetic hotspot related to acid stress resistance. Further attention was devoted to the ornithine decarboxylase pathway, which affords putrescine from ornithine. Studies were performed on three lactic acid bacteria belonging to different species. The ODC pathway was always shown to be involved in cytosolic pH alkalinisation and acid shock survival, which were observed to occur with a concomitant increase in putrescine production. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Quinic Acid Could Be a Potential Rejuvenating Natural Compound by Improving Survival of Caenorhabditis elegans under Deleterious Conditions

    Science.gov (United States)

    Zhang, Longze; Zhang, Junjing

    2012-01-01

    Abstract Quinic acid (QA) is an active ingredient of Cat's Claw (Uncaria tomentosa), which is found to be active in enhancing DNA repair and immunity in model systems and able to generate neuroprotective effects in neurons. However, QA's role in improving survival is not well studied. Here we report that QA can provide protection in Caenorhabidits elegans and improve worm survival under stress. Under heat stress and oxidative stress, QA-treated wild-type C. elegans N2 (N2) survived 17.8% and 29.7% longer, respectively, than the control worms. Our data suggest that under heat stress, QA can upregulate the expression of the small heat shock protein hsp-16.2 gene, which could help the worms survive a longer time. We also found that QA extended the C. elegans mutant VC475 [hsp-16.2 (gk249)] life span by 15.7% under normal culture conditions. However, under normal culture conditions, QA did not affect hsp-16.2 expression, but upregulated the expression of daf-16 and sod-3 in a DAF-16–dependent manner, and downregulated the level of reactive oxygen species (ROS), suggesting that under normal conditions QA acts in different pathways. As a natural product, QA demonstrates great potential as a rejuvenating compound. PMID:22950425

  10. Survival of Probiotic Lactobacilli in Acidic Environments Is Enhanced in the Presence of Metabolizable Sugars

    OpenAIRE

    Corcoran, B. M.; Stanton, C.; Fitzgerald, G. F.; Ross, R. P.

    2005-01-01

    Lactobacillus rhamnosus GG is an industrially significant probiotic strain with proven health benefits. In this study, the effect of glucose on L. rhamnosus GG survival was analyzed in simulated gastric juice at pH 2.0. It was found that the presence of 19.4 mM glucose resulted in up to 6-log10-enhanced survival following 90 min of exposure. Further work with dilute HCl confirmed that glucose was the sole component responsible. Comparative analysis with other Lactobacillus strains revealed th...

  11. Decreased Polyunsaturated Fatty Acid Content Contributes to Increased Survival in Human Colon Cancer

    Directory of Open Access Journals (Sweden)

    Manuela Oraldi

    2009-01-01

    Full Text Available Among diet components, some fatty acids are known to affect several stages of colon carcinogenesis, whereas others are probably helpful in preventing tumors. In light of this, our aim was to determine the composition of fatty acids and the possible correlation with apoptosis in human colon carcinoma specimens at different Duke's stages and to evaluate the effect of enriching human colon cancer cell line with the possible reduced fatty acid(s. Specimens of carcinoma were compared with the corresponding non-neoplastic mucosa: a significant decrease of arachidonic acid, PPARα, Bad, and Bax and a significant increase of COX-2, Bcl-2, and pBad were found. The importance of arachidonic acid in apoptosis was demonstrated by enriching a Caco-2 cell line with this fatty acid. It induced apoptosis in a dose- and time-dependent manner via induction of PPARα that, in turn, decreased COX-2. In conclusion, the reduced content of arachidonic acid is likely related to carcinogenic process decreasing the susceptibility of cancer cells to apoptosis.

  12. Effect of Organic Acids and Marination Ingredients on the Survival of Campylobacter jejuni on Meat

    DEFF Research Database (Denmark)

    Birk, Tina; Grønlund, Anne Christine Jørgensen; Christensen, Bjarke Bak

    2010-01-01

    The aim of this study was to determine whether marination of chicken meat in different food ingredients call be used to reduce populations of Campylobacter jejuni strains, were exposed to different organic acids (tartaric, acetic. lactic, malic, and citric acids) and food marinating ingredients...... inoculated in brain heart infusion broth containing 0.3% tartaric acid. On chicken meat medallions, reductions of C. jejuni were 0.5 to 2 log units when tartaric acid solutions (2, 4, 6, and 10%) were spread onto the meal. Analysis of acidic food ingredient (e.g., vinegar. lemon juice, pomegranate syrup...... of approximately 1.2 log units after 3 days of storage. Taste evaluations of chicken meat that had been marinated and then fried were graded positively for flavor and texture. Thus, Success was achieved ill creating I marinade with an acceptable taste that reduced the counts of C. jejuni....

  13. Influence of zoledronic acid on disseminated tumor cells in bone marrow and survival: results of a prospective clinical trial

    International Nuclear Information System (INIS)

    Banys, Malgorzata; Wackwitz, Birgit; Hirnle, Peter; Wallwiener, Diethelm; Fehm, Tanja; Solomayer, Erich-Franz; Gebauer, Gerhard; Janni, Wolfgang; Krawczyk, Natalia; Lueck, Hans-Joachim; Becker, Sven; Huober, Jens; Kraemer, Bernhard

    2013-01-01

    The presence of disseminated tumor cells (DTC) in bone marrow (BM) of breast cancer patients is associated with reduced clinical outcome. Bisphosphonate treatment was shown to eradicate DTC from BM in several studies. This controlled randomized open-label multi-center study aimed to investigate the influence of zoledronic acid (ZOL) on DTC and survival of breast cancer patients (Clinical Trial Registration Number: NCT00172068). Patients with primary breast cancer and DTC-positive bone marrow were randomized to treatment with ZOL plus adjuvant systemic therapy (n = 40) or adjuvant systemic therapy alone (n = 46) between 03/2002 and 12/2004. DTC were identified by immunocytochemistry using the pancytokeratin antibody A45B/B3 and by cytomorphology. The change in DTC numbers at 12 months and 24 months versus baseline, as well as patient outcomes were evaluated. 86 patients could be included into survival analysis (median follow-up: 88 months, range: 8–108 mths). Patients in the control group were more likely to die during follow-up than those in the ZOL-group (11% vs. 2%, p = 0.106). 15% of patients in the control group presented with relapse whereas only 8% of ZOL group patients developed metastatic or recurrent disease during follow-up (p = 0.205). At 24 months, 16% of patients from the control group were still DTC positive, whereas all patients treated with ZOL became DTC negative (p = 0.032). Patients presenting with persistent DTC 12 months after diagnosis had significantly shorter overall survival (p = 0.011). Bisphosphonate therapy contributes to eradication of disseminated tumor cells. The positive influence of bisphosphonates on survival in the adjuvant setting may be due to their effects on DTC. ClinicalTrials.gov Identifier: http://clinicaltrials.gov/show/NCT00172068 [Zoledronic Acid in the Treatment of Breast Cancer With Minimal Residual Disease in the Bone Marrow (MRD-1)

  14. Effects of acid adaptation and modified marinades on survival of postdrying Salmonella contamination on beef jerky during storage.

    Science.gov (United States)

    Calicioglu, Mehmet; Sofos, John N; Kendall, Patricia A; Smith, Gary C

    2003-03-01

    This study was undertaken to evaluate the survival of acid-adapted and nonadapted Salmonella cultures inoculated after drying on beef jerky that had been treated with marinades before drying at 60 degrees C for 10 h. Beef slices were (i) not treated prior to refrigeration at 4 degrees C for 24 h (control [C]); (ii) marinated with traditional marinade (TM), (iii) marinated with TM modified with 1.2% sodium lactate, 9% acetic acid, and 68% soy sauce containing 5% ethanol (MM) at twice the amount used in the TM treatment; (iv) dipped into 5% acetic acid and then marinated with TM (AATM); and (v) dipped into 1% Tween 20, then dipped into 5% acetic acid, and then marinated with TM (TWTM); after each treatment, meat slices were refrigerated at 4 degrees C for 24 h prior to drying. Dried slices were inoculated with acid-adapted or nonadapted Salmonella (ca. 5.7 log CFU/cm2) prior to aerobic storage at 25 degrees C for 60 days. Tryptic soy agar with 0.1% pyruvate, as well as xylose-lysine-tergitol 4 (XLT4) agar, was used to determine survivor counts. Bacterial decreases achieved with the different treatments were found to be in the following order: TWTM (5.4 to 6.3 log units) > or = AATM > or = MM > C > or = TM (2.9 to 5.1 log units). Acid-adapted Salmonella decreased faster than nonadapted Salmonella for all treatments. Bacterial populations decreased to below the detection limit (-0.4 log CFU/cm2) in as few as 14 days or remained detectable by direct plating after 60 days of storage, depending on acid adaptation, treatment, and agar media. The results of this study indicate that the modified marinades used in jerky processing and the low water activity of the dried product provide antimicrobial effects against possible postprocessing contamination with Salmonella, while the preparation of cultures under acid-adaptation conditions did not increase Salmonella survival during storage and may have reduced it.

  15. A new regulatory mechanism for bacterial lipoic acid synthesis

    OpenAIRE

    Zhang, Huimin; Luo, Qixia; Gao, Haichun; Feng, Youjun

    2015-01-01

    Lipoic acid, an essential enzyme cofactor, is required in three domains of life. In the past 60?years since its discovery, most of the pathway for lipoic acid synthesis and metabolism has been elucidated. However, genetic control of lipoic acid synthesis remains unclear. Here, we report integrative evidence that bacterial cAMP-dependent signaling is linked to lipoic acid synthesis in Shewanella species, the certain of unique marine-borne bacteria with special ability of metal reduction. Physi...

  16. kinetics and mechanism of reaction of acidic chlorite with ...

    African Journals Online (AJOL)

    overall third order rate constants for the reaction of acidic chlorite with Nile blue and Meldola's blue were (0.363 ... of interest to investigate, how these differences affect the reaction rates of these dyes with acidic chlorite. .... To establish the order with respect to chlorite and acid, the effect of initial concentration of chlorite and ...

  17. Novel toughened polylactic acid nanocomposite: Mechanical, thermal and morphological properties

    International Nuclear Information System (INIS)

    Balakrishnan, Harintharavimal; Hassan, Azman; Wahit, Mat Uzir; Yussuf, A.A.; Razak, Shamsul Bahri Abdul

    2010-01-01

    The objective of the study is to develop a novel toughened polylactic acid (PLA) nanocomposite. The effects of linear low density polyethylene (LLDPE) and organophilic modified montmorillonite (MMT) on mechanical, thermal and morphological properties of PLA were investigated. LLDPE toughened PLA nanocomposites consisting of PLA/LLDPE blends, of composition 100/0 and 90/10 with MMT content of 2 phr and 4 phr were prepared. The Young's and flexural modulus improved with increasing content of MMT indicating that MMT is effective in increasing stiffness of LLDPE toughened PLA nanocomposite even at low content. LLDPE improved the impact strength of PLA nanocomposites with a sacrifice of tensile and flexural strength. The tensile and flexural strength also decreased with increasing content of MMT in PLA/LLDPE nanocomposites. The impact strength and elongation at break of LLDPE toughened PLA nanocomposites also declined steadily with increasing loadings of MMT. The crystallization temperature and glass transition temperature dropped gradually while the thermal stability of PLA improved with addition of MMT in PLA/LLDPE nanocomposites. The storage modulus of PLA/LLDPE nanocomposites below glass transition temperature increased with increasing content of MMT. X-ray diffraction and transmission electron microscope studies revealed that an intercalated LLDPE toughened PLA nanocomposite was successfully prepared at 2 phr MMT content.

  18. Physical training is beneficial to functional status and survival in patients with prolonged mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Shiauyee Chen

    2011-09-01

    Conclusion: Six weeks physical therapy training plus 6 weeks unsupervised maintenance exercise enhanced functional levels and increased survival for the PMV patients compared with those with no such intervention. Early physical therapy interventions are needed for the PMV patients in respiratory care centers. [J Formos Med Assoc 2011; 110(X:XX–XX

  19. Mechanisms and mediation in survival analysis: towards an integrated analytical framework.

    Science.gov (United States)

    Pratschke, Jonathan; Haase, Trutz; Comber, Harry; Sharp, Linda; de Camargo Cancela, Marianna; Johnson, Howard

    2016-02-29

    A wide-ranging debate has taken place in recent years on mediation analysis and causal modelling, raising profound theoretical, philosophical and methodological questions. The authors build on the results of these discussions to work towards an integrated approach to the analysis of research questions that situate survival outcomes in relation to complex causal pathways with multiple mediators. The background to this contribution is the increasingly urgent need for policy-relevant research on the nature of inequalities in health and healthcare. The authors begin by summarising debates on causal inference, mediated effects and statistical models, showing that these three strands of research have powerful synergies. They review a range of approaches which seek to extend existing survival models to obtain valid estimates of mediation effects. They then argue for an alternative strategy, which involves integrating survival outcomes within Structural Equation Models via the discrete-time survival model. This approach can provide an integrated framework for studying mediation effects in relation to survival outcomes, an issue of great relevance in applied health research. The authors provide an example of how these techniques can be used to explore whether the social class position of patients has a significant indirect effect on the hazard of death from colon cancer. The results suggest that the indirect effects of social class on survival are substantial and negative (-0.23 overall). In addition to the substantial direct effect of this variable (-0.60), its indirect effects account for more than one quarter of the total effect. The two main pathways for this indirect effect, via emergency admission (-0.12), on the one hand, and hospital caseload, on the other, (-0.10) are of similar size. The discrete-time survival model provides an attractive way of integrating time-to-event data within the field of Structural Equation Modelling. The authors demonstrate the efficacy

  20. Ursolic acid improves survival and attenuates lung injury in septic rats induced by cecal ligation and puncture.

    Science.gov (United States)

    Hu, Zhansheng; Gu, Zhilong; Sun, Meina; Zhang, Ke; Gao, Penghui; Yang, Qinwu; Yuan, Yuan

    2015-04-01

    Sepsis is characterized as a systemic inflammatory response syndrome during infection, which can result in multiple organ dysfunction and death. Ursolic acid (UA), a pentacyclic triterpene acid, has been reported to have potent anti-inflammatory and antioxidant properties. The aim of this study was to detect the possible protective effects of UA on sepsis-evoked acute lung injury. A rat model of sepsis induced by cecal ligation and puncture (CLP) was used. Rats were injected intraperitoneally with UA (10 mg/kg) after CLP, and then the survival was determined twice a day for 4 d. The protective effects of UA on CLP-induced acute lung injury were assayed at 24 h after CLP. The results revealed that UA treatment markedly improved the survival of septic rats, and attenuated CLP-induced lung injury, including reduction of lung wet/dry weight ratio, infiltration of leukocytes and proteins, myeloperoxidase activity, and malondialdehyde content. In addition, UA significantly decreased the serum levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β, inhibited the expression of inducible nitric oxide synthase and cyclooxygenase-2 in the lung, which are involved in the productions of nitric oxide and prostaglandin E2. These findings indicate that UA exerts protective effects on CLP-induced septic rats. UA may be a potential therapeutic agent against sepsis. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Cyclobutyl methyl ketone as a model compound for pinonic acid to elucidate oxidation mechanisms

    Directory of Open Access Journals (Sweden)

    A. P. Praplan

    2012-11-01

    Full Text Available Although oxidation of the atmospherically relevant compound α-pinene has been extensively studied, chemical mechanisms leading to the formation of later generation oxidation products remain poorly understood. The present work uses cyclobutyl methyl ketone (CMK to study the oxidation mechanism of pinonic acid, an α-pinene reaction product, by hydroxyl radicals (·OH. CMK has a similar but simpler chemical structure compared to pinonic acid. Succinic acid, 4-hydroxybutanoic acid and 4-oxobutanoic acid were identified as first generation products of CMK. These observed organic acids were compared to compounds found in secondary organic aerosol formed from the oxidation of α-pinene. Results suggest that 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA, terpenylic % corrected name for MBTCA (3-methyl-1,2,3-butanetricarboxylic acid acid and diaterpenylic acid acetate are first generation products of OH oxidation of pinonic acid. Therefore, there is strong evidence that ·OH oxidation greatly increases the oxygenation of organic compounds (e.g. monocarboxylic acid to tricarboxylic acid through radical mechanisms, without requiring a stable intermediate. These observations cannot be explained by traditional atmospheric chemistry mechanisms.

  2. Implication of acidic lipids in 5-hydroxytryptamine receptor mechanisms

    International Nuclear Information System (INIS)

    Yoshikawa, S.; Ishitani, R.

    1985-01-01

    To establish the possible involvement of acidic lipids in 5-HT receptor mechanisms, the authors subjected whole rat brain synaptic plasma membranes to treatment with several kinds of lipid-modifying reagents and examined the [ 3 H]5-HT and [ 3 H]spiperone binding properties of the membranes. [ 3 H]5-HT binding was decreased by treatment with Azure A, while [ 3 H]spiperone binding was not altered. Similarly, prior treatment with arylsulphatase reduced the former binding, but had no effect on the latter binding. On the other hand, neither [ 3 H]ligand binding was sensitive to phospholipases C and D. In contrast, prior treatment with phospholipase A 2 (unheated) drastically decreased the [ 3 H]5-HT binding and also affected the [ 3 H]spiperone binding to some extent. Chelation of Ca 2+ by EGTA (5 mM) prior to incubation of membranes with the unheated phospholipase A 2 did not completely prevent the inhibitory effect of this enzyme on [ 3 H]5-HT binding, while in the heated enzyme (at 100 0 C for 10 min) EGTA exhibited this preventive effect perfectly. Furthermore, it was an interesting find that at least a low concentration of the heated phospholipase A 2 (0.01 U) had no effect on the [ 3 H]spiperone binding, as contrasted with the case of [ 3 H]5-HT binding. In addition, the reduction of [ 3 H]5-HT binding capacity in membranes treated with phospholipase A 2 (heated and unheated) was restored only slightly by treatment with BSA (1%). 17 references, 4 tables

  3. Study on Adsorption Mechanism of Acid-Modified Bentonite

    Science.gov (United States)

    Peng, L. G.; Zhu, J. H.; Han, J.; Wang, X. X.; Zhao, M.; Cheng, H. Q.; Zhang, X.

    2017-12-01

    The acid-modified bentonite was prepared by sulfuric acid acidification, we compared it in chemical composition, layer structure and adsorption performance before and after the adsorption of Cu2+ by joint analysis of FT-IR, XRD, and ICP. The results indicated that: XRD showed that Cu2+ went into the bentonite layer, the analysis of ICP showed: Cu2+ exchange reaction didn’t take place, only coordination reaction occurred, i.e. acid-modified bentonite adsorbs cooper irons mainly in a way of cooperation reaction; the adsorption of acid-modified bentonite conforms to the Langmuir monolayer model and the pseudo-second-order kinetic model.

  4. Mechanisms and mediation in survival analysis: towards an integrated analytical framework.

    LENUS (Irish Health Repository)

    Haase, Trutz

    2016-02-29

    A wide-ranging debate has taken place in recent years on mediation analysis and causal modelling, raising profound theoretical, philosophical and methodological questions. The authors build on the results of these discussions to work towards an integrated approach to the analysis of research questions that situate survival outcomes in relation to complex causal pathways with multiple mediators. The background to this contribution is the increasingly urgent need for policy-relevant research on the nature of inequalities in health and healthcare.

  5. Amino Acid Neurotransmitters; Mechanisms of Their Uptake into Synaptic Vesicles

    Science.gov (United States)

    1991-08-01

    phenylhydrazone (CCCP), ouabain. L-glutamate (disodium gan and Whittaker, 1966: Rassin , 1972; Kontro et al., salt), D-aspartate, diaminobutyric acid (DABA... Rassin D. K. 1 972) Amino acids as putative transmitters: failure to endings Isynaptosomes) in different regions of brain: effect of bind synaptic

  6. Understanding the 3-hydroxypropionic acid tolerance mechanism in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kildegaard, Kanchana Rueksomtawin; Juncker, Agnieszka; Hallstrom, Bjorn

    2013-01-01

    3-Hydroxypropionic acid (3HP) is an important platform chemical that can be converted into other valuable chemicals such as acrylic acid and its derivatives that are used in baby diap ers, various plastics, and paints. With the oil and gas resources becoming limiting, biotechnolo gy offers...

  7. The effect of aspirated barium sulfate, iodixanol, and diatrizoic acid on survival and lung injury in a lagomorph model.

    Science.gov (United States)

    Siddiqui, M Tausif; Litts, Juliana K; Cheney, Diane M; Kuhn, Maggie A; Nativ-Zeltzer, Nogah; Belafsky, Peter C

    2017-05-01

    Contrast agents are an integral component of the video fluoroscopic swallow study. Agents commonly used include barium sulfate (E-Z Paque), iodixanol (Visipaque), and diatrizoic acid (Gastrografin). Barium is water insoluble, whereas iodixanol and diatrizoic acid are water-soluble iodine-based agents. The detrimental effect of these agents on the lungs has not been systematically evaluated. Our aim was to evaluate and compare the effects of aspirated barium, iodixanol, and diatrizoic acid on pulmonary injury in a lagomorph model. Animal model. Twenty adult male New Zealand White rabbits were divided into four groups (n = 5). Group 1 received 3 mL of barium sulfate injected into the trachea for 3 consecutive days. Group 2 received 3 mL of iodixanol injected into the trachea for 3 consecutive days. Group 3 received 3 mL of diatrizoic acid injected into the trachea for 3 consecutive days. A control group received 3 mL of air injected into the trachea under an identical protocol. All animals were euthanized on day 4, and the lung and trachea were harvested for blinded histopathologic analysis. The primary outcome measure was survival. The secondary endpoint was a blinded, histologic grading system of lung injury. Two animals in the barium group, one in the diatrizoic acid group, and 0 animals in the iodixanol and control groups died. The overall lung injury score for the barium (60.60 ± 6.34) and iodixanol groups (52.30 ± 3.11) were significantly higher (worse) than the diatrizoic acid (49.60 ± 7.64) and control groups (37.80 ± 3.56) (P barium sulfate (E-Z Paque) over 3 consecutive days causes more severe lung injury in a lagomorph model than 3 mL of aspirated iodixanol (Visipaque) and diatrizoic acid (Gastrografin). Diatrizoic acid caused the least histologic evidence of lung injury. NA Laryngoscope, 127:E148-E152, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  8. Acid base imbalances in ill neonatal foals and their association with survival.

    Science.gov (United States)

    Viu, J; Armengou, L; Ríos, J; Cesarini, C; Jose-Cunilleras, E

    2017-01-01

    Acid-base imbalances observed in human paediatric patients are associated with outcome. Likewise, neonatal foals may have different acid-base imbalances associated with diagnosis or prognosis. To determine acid-base imbalances by the quantitative method in ill neonatal foals and assess their association with diagnosis and prognosis. Observational prospective clinical study. This study included 65 ill neonatal foals (32 septic, 33 nonseptic) admitted to an equine referral hospital from 2005 to 2011with acid-base parameters determined on admission and a control group of 33 healthy neonatal foals. Blood pH, pCO 2 , sodium, potassium, chloride, L-lactate, albumin and phosphate concentrations were determined. Bicarbonate, globulin, measured strong ion difference (SID m ), nonvolatile weak buffer concentrations (A tot ), base excess and its components were calculated. Analysis of covariance (ANCOVA) and multiple linear regression statistical analyses were performed. Results are summarised as mean ± s.d. for normally distributed variables and median [25-75th percentiles] for non-normally distributed ones. A total of 63% of ill foals had respiratory alkalosis and 58.5% had SID m acidosis. The combination of both alterations was detected in 21 of 65 ill foals and abnormal pH was found in 24 of 65. Compared with healthy foals, ill foals had significantly lower SID m (nonseptic 31.6 ± 6.3 [Pacid-base imbalances observed in ill foals were respiratory alkalosis, SID m acidosis or mixed respiratory alkalosis with strong ion acidosis. Increased venous pCO 2 and blood L-lactate concentration were associated with poor outcome. © 2015 EVJ Ltd.

  9. Administration of isoferulic acid improved the survival rate of lethal influenza virus pneumonia in mice

    Directory of Open Access Journals (Sweden)

    Shinya Sakai

    2001-01-01

    Full Text Available Background: Isoferulic acid (IFA is a main active ingredient of the rhizoma of Cimicifuga heracleifolia, which is used frequently in Japanese traditional medicine as an anti-inflammatory drug. It has been revealed that IFA inhibits the production of macrophage inflammatory protein-2 (MIP-2, which is a murine counterpart of the chemokine family that may contribute to the pathogenesis of inflammatory diseases through the chemotactic activity for inflammatory and immune effector cells.

  10. Mechanism involved in enhancement of osteoblast differentiation by hyaluronic acid

    International Nuclear Information System (INIS)

    Kawano, Michinao; Ariyoshi, Wataru; Iwanaga, Kenjiro; Okinaga, Toshinori; Habu, Manabu; Yoshioka, Izumi; Tominaga, Kazuhiro; Nishihara, Tatsuji

    2011-01-01

    Research highlights: → In this study was to investigate the effects of HA on osteoblast differentiation induced by BMP-2. → MG63 cells were incubated with BMP-2 and HA for various time periods. → Phosphorylation of Smad 1/5/8, p38, and ERK proteins was determined by western blot analysis. To elucidate the nuclear translocation of phosphorylated Smad 1/5/8, stimulated cells were subjected to immunofluorescence microscopy. → HA enhanced BMP-2 induces osteoblastic differentiation in MG63 cells via down-regulation of BMP-2 antagonists and ERK phosphorylation. -- Abstract: Objectives: Bone morphogenetic protein-2 (BMP-2) is expected to be utilized to fill bone defects and promote healing of fractures. However, it is unable to generate an adequate clinical response for use in bone regeneration. Recently, it was reported that glycosaminoglycans, including heparin, heparan sulfate, keratan sulfate, dermatan sulfate, chondroitin-4-sulfate, chondroitin-6-sulfate, and hyaluronic acid (HA), regulate BMP-2 activity, though the mechanism by which HA regulates osteogenic activities has not been fully elucidated. The aim of this study was to investigate the effects of HA on osteoblast differentiation induced by BMP-2. Materials and methods: Monolayer cultures of osteoblastic lineage MG63 cells were incubated with BMP-2 and HA for various time periods. To determine osteoblastic differentiation, alkaline phosphatase (ALP) activity in the cell lysates was quantified. Phosphorylation of Smad 1/5/8, p38, and ERK proteins was determined by Western blot analysis. To elucidate the nuclear translocation of phosphorylated Smad 1/5/8, stimulated cells were subjected to immunofluorescence microscopy. To further elucidate the role of HA in enhancement of BMP-2-induced Smad signaling, mRNA expressions of the BMP-2 receptor antagonists noggin and follistatin were detected using real-time RT-PCR. Results: BMP-2-induced ALP activation, Smad 1/5/8 phosphorylation, and nuclear translocation

  11. Mechanism involved in enhancement of osteoblast differentiation by hyaluronic acid

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Michinao [Division of Maxillofacial Diagnostic and Surgical Science, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Ariyoshi, Wataru [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Iwanaga, Kenjiro [Division of Maxillofacial Diagnostic and Surgical Science, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Okinaga, Toshinori [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Habu, Manabu [Division of Maxillofacial Diagnostic and Surgical Science, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Yoshioka, Izumi [Division of Oral and Maxillofacial Surgery, Department of Medicine of Sensory and Motor Organs, University of Miyazaki, Kiyotake, Miyazaki 889-1692 (Japan); Tominaga, Kazuhiro [Division of Maxillofacial Diagnostic and Surgical Science, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Oral Bioresearch Center, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Nishihara, Tatsuji, E-mail: tatsujin@kyu-dent.ac.jp [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, Kitakyushu 803-8580 (Japan); Oral Bioresearch Center, Kyushu Dental College, Kitakyushu 803-8580 (Japan)

    2011-02-25

    Research highlights: {yields} In this study was to investigate the effects of HA on osteoblast differentiation induced by BMP-2. {yields} MG63 cells were incubated with BMP-2 and HA for various time periods. {yields} Phosphorylation of Smad 1/5/8, p38, and ERK proteins was determined by western blot analysis. To elucidate the nuclear translocation of phosphorylated Smad 1/5/8, stimulated cells were subjected to immunofluorescence microscopy. {yields} HA enhanced BMP-2 induces osteoblastic differentiation in MG63 cells via down-regulation of BMP-2 antagonists and ERK phosphorylation. -- Abstract: Objectives: Bone morphogenetic protein-2 (BMP-2) is expected to be utilized to fill bone defects and promote healing of fractures. However, it is unable to generate an adequate clinical response for use in bone regeneration. Recently, it was reported that glycosaminoglycans, including heparin, heparan sulfate, keratan sulfate, dermatan sulfate, chondroitin-4-sulfate, chondroitin-6-sulfate, and hyaluronic acid (HA), regulate BMP-2 activity, though the mechanism by which HA regulates osteogenic activities has not been fully elucidated. The aim of this study was to investigate the effects of HA on osteoblast differentiation induced by BMP-2. Materials and methods: Monolayer cultures of osteoblastic lineage MG63 cells were incubated with BMP-2 and HA for various time periods. To determine osteoblastic differentiation, alkaline phosphatase (ALP) activity in the cell lysates was quantified. Phosphorylation of Smad 1/5/8, p38, and ERK proteins was determined by Western blot analysis. To elucidate the nuclear translocation of phosphorylated Smad 1/5/8, stimulated cells were subjected to immunofluorescence microscopy. To further elucidate the role of HA in enhancement of BMP-2-induced Smad signaling, mRNA expressions of the BMP-2 receptor antagonists noggin and follistatin were detected using real-time RT-PCR. Results: BMP-2-induced ALP activation, Smad 1/5/8 phosphorylation, and

  12. Mechanism and kinetics of mineral weathering under acid conditions

    NARCIS (Netherlands)

    Anbeek, C.

    1994-01-01

    This study deals with the relationships between crystal structure, grain diameter, surface morphology and dissolution kinetics for feldspar and quartz under acid conditions.

    Intensively ground samples from large, naturally weathered mineral fragments are frequently used in

  13. Dietary fatty acids affecting hepatic metabolism and atherosclerosis - mechanisms unravelled using a proteomics approach

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Gutierrez, G.; Roos, B. de

    2009-07-01

    Dietary fatty acids play an important role in the aetiology of coronary heart disease. The effects of dietary fatty acids on lipoprotein metabolism are well described, but additional or alternative mechanisms relating to potential influence on coronary heart disease are not known. This review describes how proteomics techniques have been used to identify proteins that are differentially regulated by dietary fatty acids. Such proteins may reveal pathways by which dietary fatty acids influence disease risk. (Author) 40 refs.

  14. Biochemical Mechanisms and Energy Strategies of Geobacter sulfurreducens for Long- Term Survival

    Science.gov (United States)

    Helmus, R. A.; Liermann, L. J.; Brantley, S. L.; Tien, M.

    2008-12-01

    Numerous species of bacteria have been observed to exhibit a growth advantage in stationary phase (GASP) phenotype, indicating that microorganisms starved of an energy source may adapt to allow for long-term survival. Understanding how Geobacter sulfurreducens persists using various metal forms as energy sources and whether a GASP phenotype develops during long-term growth are important for efficient application of this bacterium to sites requiring engineered bioremediation of soluble metals. Thus, we investigated the growth kinetics and survival of G. sulfurreducens. The growth rate of G. sulfurreducens was highest when cultured with soluble iron and generally higher on iron oxide than manganese oxide, suggesting that soluble metal forms are more readily utilized as energy sources by G. sulfurreducens. By monitoring the abundance of G. sulfurreducens in batch cultures for >6 months, distinct growth, stationary, and prolonged starvation phases were observed and a cell density of 105- 106 cells/mL persisted under long-term starvation conditions. The outgrowth of an aged G. sulfurreducens strain co-cultured with a young strain was monitored as a measure of the existence of the GASP phenotype. As the strains aged, the rpoS gene was cloned and sequenced at different stages of growth to identify mutations corresponding to a growth advantage. The results of these studies provide insight into the use of various metal forms for growth by G. sulfurreducens and its ability to persist when starved of energy sources.

  15. Inhibitory mechanism against oxidative stress of caffeic acid

    Directory of Open Access Journals (Sweden)

    Farhan Ahmed Khan

    2016-10-01

    Full Text Available The purpose of this article is to summarize the reported antioxidant activities of a naturally abundant bioactive phenolic acid, caffeic acid (CA, 3,4-dihydroxycinnamic acid, so that new avenues for future research involving CA can be explored. CA is abundantly found in coffee, fruits, vegetables, oils, and tea. CA is among the most potential and abundantly found in nature, hydroxycinnamic acids with the potential of antioxidant behavior. Reactive oxygen species produced as a result of endogenous processes can lead to pathophysiological disturbances in the human body. Foods containing phenolic substances are a potential source for free radical scavenging; these chemicals are known as antioxidants. This review is focused on CA's structure, availability, and potential as an antioxidant along with its mode of action. A brief overview of the literature published about the prooxidant potential of caffeic acid as well as the future perspectives of caffeic acid research is described. CA can be effectively employed as a natural antioxidant in various food products such as oils.

  16. Studies on the mechanism of action of a novel anorectic agent, (--)-threo-chlorocitric acid.

    Science.gov (United States)

    Triscari, J; Sullivan, A C

    1981-08-01

    (--)-threo-Chlorocitric acid, a novel and potent anorectic agent in rats and dogs, decreased food intake to a comparable extent in rats fed chow, low fat, or high fat diets. This inhibition of food intake was not the result of conditioned aversion. Unlike (--)-threo-hydroxycitric acid, a structurally related compound which inhibits fatty acid synthesis, (--)-threo-chlorocitric acid did not suppress fatty acid synthesis in an isolated hepatocyte system or in vivo. (--)-threo-Chlorocitric acid significantly delayed the rate of gastric emptying. Of the four stereoisomers of chlorocitric acid, (--)-threo-chlorocitric acid was the most active both in delaying gastric emptying and producing anorexia in rats. It is suggested that the mechanism by which (--)-threo-chlorocitric acid may suppress food intake is through a reduction of gastric emptying.

  17. Influence of sub-lethal stresses on the survival of lactic acid bacteria after spray-drying in orange juice.

    Science.gov (United States)

    Barbosa, J; Borges, S; Teixeira, P

    2015-12-01

    The demand for new functional non-dairy based products makes the production of a probiotic orange juice powder an encouraging challenge. However, during drying process and storage, loss of viability of the dried probiotic cultures can occur, since the cells are exposed to various stresses. The influence of sub-lethal conditions of temperature, acidic pH and hydrogen peroxide on the viability of Pediococcus acidilactici HA-6111-2 and Lactobacillus plantarum 299v during spray drying in orange juice and subsequent storage under different conditions was investigated. At the end of storage, the survival of both microorganisms through simulated gastro-intestinal tract (GIT) conditions was also determined. The viability of cells previously exposed to each stress was not affected by the drying process. However, during 180 days of storage at room temperature, unlike P. acidilactici HA-6111-2, survival of L. plantarum 299v was enhanced by prior exposure to sub-lethal conditions. Previous exposure to sub-lethal stresses of each microorganism did not improve their viability after passage through simulated GIT. Nevertheless, as cellular inactivation during 180 days of storage was low, both microorganisms were present in numbers of ca. 10(7) cfu/mL at the end of GIT. This is an indication that both bacteria are good candidates for use in the development of an orange juice powder with functional characteristics. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. A biopulping mechanism : creation of acid groups on fiber

    Science.gov (United States)

    Chris Hunt; William Kenealy; Eric Horn; Carl Houtman

    2004-01-01

    We investigated how biopulping modifies chemical and physical properties of wood and how these changes affect the properties of the resulting fiber. Mechanical and chemical testing revealed wood cell changes during 2 weeks of colonization by Ceriporiopsis subvermispora. Typical mechanical properties, such as modulus of elasticity and maximum load, tracked reductions in...

  19. Mechanism of Oxidation of Brilliant Cresyl Blue with Acidic Chlorite ...

    African Journals Online (AJOL)

    diethylamino-8-methyl-phenoxazine chloride) (BB+) by chlorite in the presence of acid is reported. Under [H+]0>[ClO2–]0>[BB+]0 conditions, the oxidation reaction followed pseudo first-order kinetics with respect to BB+. During the reaction, chlorite ...

  20. Peroxisomal fatty acid uptake mechanism in Saccharomyces cerevisiae.

    NARCIS (Netherlands)

    van Roermund, C.W.T.; Ijlst, L.; Majczak, W.; Waterham, H.R.; Folkerts, H.; Wanders, R.J.A.; Hellingwerf, K.J.

    2012-01-01

    Peroxisomes play a major role in human cellular lipid metabolism, including fatty acid beta-oxidation. The most frequent peroxisomal disorder is X-linked adrenoleukodystrophy, which is caused by mutations in ABCD1. The biochemical hallmark of X-linked adrenoleukodystrophy is the accumulation of very

  1. Peroxisomal Fatty Acid Uptake Mechanism in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    van Roermund, Carlo W. T.; Ijlst, Lodewijk; Majczak, Wiktor; Waterham, Hans R.; Folkerts, Hendrik; Wanders, Ronald J. A.; Hellingwerf, Klaas J.

    2012-01-01

    Peroxisomes play a major role in human cellular lipid metabolism, including fatty acid beta-oxidation. The most frequent peroxisomal disorder is X-linked adrenoleukodystrophy, which is caused by mutations in ABCD1. The biochemical hallmark of X-linked adrenoleukodystrophy is the accumulation of very

  2. Hypolipidemic mechanism of oryzanol components- ferulic acid and phytosterols.

    Science.gov (United States)

    Bhaskaragoud, G; Rajath, S; Mahendra, V P; Kumar, G Sunil; Gopala Krishna, A G; Kumar, G Suresh

    2016-07-22

    The effect of oryzanol (well known hypolipidemic component in rice bran oil) and its chemical constituents- ferulic acid (FA) and phytosterols on hypolipidemia were investigated. Docking (in silico) studies showed that FA had a better binding ability with lipase while sterols bound well with HMG-CoA reductase. Further in vivo studies of feeding high fat (30%) to rats increased body weights, serum TC, TG, non-HDL-C and reduced HDL-C were observed, compared to normal diet fed group (ND). ORZ treated groups alleviated the lipid profile. Furthermore, increased organ weights, higher intestinal lipase activity, and liver lipid peroxidation was observed in the high-fat group (HF). These effects were ameliorated in oryzanol concentrate fed groups (ORZ). Higher fecal fat was found in ORZ groups, analysis of fecal matter by mass spectroscopy revealed the presence of FA. In vitro, a bile acid binding study supported the strong affinity of sterol towards bile acids. In conclusion, oryzanol in the intestine is cleaved into FA and sterol by intestinal lipase enzymes both lipase and HMG-CoA reductase activities were inhibited, respectively. These hydrolysates eliminated the bile acids, thus lowering lipid profiles. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. CSF Amino Acids, Pterins and Mechanism of the Ketogenic Diet

    Directory of Open Access Journals (Sweden)

    J. Gordon Millichap

    2015-11-01

    Full Text Available Investigators from Hospital Sant Joan de Deu, Barcelona, Spain, studied the relationship between the etiology of refractory childhood epilepsy, CSF neurotransmitters, pterins, and amino acids, and response to a ketogenic diet in 60 patients with refractory epilepsy, 83% focal and 52% idiopathic.

  4. An easily reversible structural change underlies mechanisms enabling desert crust cyanobacteria to survive desiccation.

    Science.gov (United States)

    Bar-Eyal, Leeat; Eisenberg, Ido; Faust, Adam; Raanan, Hagai; Nevo, Reinat; Rappaport, Fabrice; Krieger-Liszkay, Anja; Sétif, Pierre; Thurotte, Adrien; Reich, Ziv; Kaplan, Aaron; Ohad, Itzhak; Paltiel, Yossi; Keren, Nir

    2015-10-01

    Biological desert sand crusts are the foundation of desert ecosystems, stabilizing the sands and allowing colonization by higher order organisms. The first colonizers of the desert sands are cyanobacteria. Facing the harsh conditions of the desert, these organisms must withstand frequent desiccation-hydration cycles, combined with high light intensities. Here, we characterize structural and functional modifications to the photosynthetic apparatus that enable a cyanobacterium, Leptolyngbya sp., to thrive under these conditions. Using multiple in vivo spectroscopic and imaging techniques, we identified two complementary mechanisms for dissipating absorbed energy in the desiccated state. The first mechanism involves the reorganization of the phycobilisome antenna system, increasing excitonic coupling between antenna components. This provides better energy dissipation in the antenna rather than directed exciton transfer to the reaction center. The second mechanism is driven by constriction of the thylakoid lumen which limits diffusion of plastocyanin to P700. The accumulation of P700(+) not only prevents light-induced charge separation but also efficiently quenches excitation energy. These protection mechanisms employ existing components of the photosynthetic apparatus, forming two distinct functional modes. Small changes in the structure of the thylakoid membranes are sufficient for quenching of all absorbed energy in the desiccated state, protecting the photosynthetic apparatus from photoinhibitory damage. These changes can be easily reversed upon rehydration, returning the system to its high photosynthetic quantum efficiency. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Yeast Cells Exposed to Exogenous Palmitoleic Acid Either Adapt to Stress and Survive or Commit to Regulated Liponecrosis and Die

    Directory of Open Access Journals (Sweden)

    Karamat Mohammad

    2018-01-01

    Full Text Available A disturbed homeostasis of cellular lipids and the resulting lipotoxicity are considered to be key contributors to many human pathologies, including obesity, metabolic syndrome, type 2 diabetes, cardiovascular diseases, and cancer. The yeast Saccharomyces cerevisiae has been successfully used for uncovering molecular mechanisms through which impaired lipid metabolism causes lipotoxicity and elicits different forms of regulated cell death. Here, we discuss mechanisms of the “liponecrotic” mode of regulated cell death in S. cerevisiae. This mode of regulated cell death can be initiated in response to a brief treatment of yeast with exogenous palmitoleic acid. Such treatment prompts the incorporation of exogenously added palmitoleic acid into phospholipids and neutral lipids. This orchestrates a global remodeling of lipid metabolism and transfer in the endoplasmic reticulum, mitochondria, lipid droplets, and the plasma membrane. Certain features of such remodeling play essential roles either in committing yeast to liponecrosis or in executing this mode of regulated cell death. We also outline four processes through which yeast cells actively resist liponecrosis by adapting to the cellular stress imposed by palmitoleic acid and maintaining viability. These prosurvival cellular processes are confined in the endoplasmic reticulum, lipid droplets, peroxisomes, autophagosomes, vacuoles, and the cytosol.

  6. Kinetic and Mechanism of Oxidation of Oxalic Acid by Cerium (IV)

    OpenAIRE

    Dr. Ammar J. Mohammed

    2005-01-01

    Kinetic and mechanism studies of the oxidation of oxalic acid by Cerium sulphate have been carried out in acid medium sulphuric acid. The uv- vis. Spectrophotometric technique was used to follow up the reaction and the selected wavelength to be followed was 320 nm. The kinetic study showed that the order of reaction is first order in Ce(IV) and fractional in oxalic acid. The effect of using different concentration of sulphuric acid on the rate of the reaction has been studied a and it was fou...

  7. Survival of Dicor glass-ceramic dental restorations over 14 years: Part I. Survival of Dicor complete coverage restorations and effect of internal surface acid etching, tooth position, gender, and age.

    Science.gov (United States)

    Malament, K A; Socransky, S S

    1999-01-01

    There are no long-term data on Dicor glass-ceramic restoration survival in the human oral cavity and the effect that different technical and clinical variables have on survival. This prospective study examined the relationship of different clinical parameters on the survival of Dicor glass-ceramic restorations in the human oral cavity. A total of 417 subjects (from 17 to 91 years of age) participated. All subjects required single unit fixed prosthodontics in any area of the mouth and/or 3-unit fixed partial dentures or cantilevered anterior restorations. They were offered the option of a gold or conventional metal-ceramic restoration, or a Dicor restoration with potentially improved esthetic results, better wear characteristics, and diminished oral plaque accumulation. Overall survival of the restorations was determined and the effect of various clinical parameters evaluated with Kaplan-Meier survival curves. Log rank tests were used to determine statistically significant differences among parameters. For the 1444 units placed, 188 failures were recorded. Total time at risk for the units was 7319 years providing an estimated risk of 2.45% per year. Probabilities of survival of "typical" acid-etched Dicor and nonacid-etched Dicor restorations were 76% and 50%, respectively, at 14.1 years (P <.001). Probabilities of survival of typical acid-etched and nonacid-etched Dicor complete coverage restorations were virtually identical to those observed in the full data set. There was a 2.2 times greater risk of failure associated with the use of nonacid-etched Dicor complete coverage than acid-etched restorations (P <.01). Complete coverage restoration survival was highest in the incisor region and decreased to the molars in both arches. Second molars showed the highest failure rate. No complete coverage restorations failed on lateral incisors during the entire study. Probability of survival of a typical acid-etched Dicor complete coverage restoration in male subjects was 71

  8. Mechanisms of triglyceride metabolism in patients with bile acid diarrhea

    OpenAIRE

    Sagar, Nidhi Midhu; McFarlane, Michael; Nwokolo, Chuka; Bardhan, Karna Dev; Arasaradnam, Ramesh Pulendran

    2016-01-01

    Bile acids (BAs) are essential for the absorption of lipids. BA synthesis is inhibited through intestinal farnesoid X receptor (FXR) activity. BA sequestration is known to influence BA metabolism and control serum lipid concentrations. Animal data has demonstrated a regulatory role for the FXR in triglyceride metabolism. FXR inhibits hepatic lipogenesis by inhibiting the expression of sterol regulatory element binding protein 1c via small heterodimer primer activity. Conversely, FXR promotes ...

  9. Acetic acid-catalyzed formation of N-phenylphthalimide from phthalanilic acid: a computational study of the mechanism.

    Science.gov (United States)

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi

    2015-05-28

    In glacial acetic acid, phthalanilic acid and its monosubstituents are known to be converted to the corresponding phthalimides in relatively good yields. In this study, we computationally investigated the experimentally proposed two-step (addition-elimination or cyclization-dehydration) mechanism at the second-order Møller-Plesset perturbation (MP2) level of theory for the unsubstituted phthalanilic acid, with an explicit acetic acid molecule included in the calculations. In the first step, a gem-diol tetrahedral intermediate is formed by the nucleophilic attack of the amide nitrogen. The second step is dehydration of the intermediate to give N-phenylphthalimide. In agreement with experimental findings, the second step has been shown to be rate-determining. Most importantly, both of the steps are catalyzed by an acetic acid molecule, which acts both as proton donor and acceptor. The present findings, along with those from our previous studies, suggest that acetic acid and other carboxylic acids (in their undissociated forms) can catalyze intramolecular nucleophilic attacks by amide nitrogens and breakdown of the resulting tetrahedral intermediates, acting simultaneously as proton donor and acceptor. In other words, double proton transfers involving a carboxylic acid molecule can be part of an extensive bond reorganization process from cyclic hydrogen-bonded complexes.

  10. New insights into the molecular mechanism of intestinal fatty acid absorption

    Science.gov (United States)

    Wang, Tony Y.; Liu, Min; Portincasa, Piero; Wang, David Q.-H.

    2013-01-01

    Background Dietary fat is the most important energy source of all the nutrients. Fatty acids, stored as triacylglycerols in the body, are an important reservoir of stored energy and derive primarily from animal fats and vegetable oils. Design Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, i.e., fatty acid transporters on the apical membrane of enterocytes. Results These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical-chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. Conclusions A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide. PMID:24102389

  11. Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

    International Nuclear Information System (INIS)

    Zrelli, K; Galy, O; Henry, N; Latour-Lambert, P; Ghigo, J M; Beloin, C; Kirwan, L

    2013-01-01

    Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms. (paper)

  12. Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

    Science.gov (United States)

    Zrelli, K.; Galy, O.; Latour-Lambert, P.; Kirwan, L.; Ghigo, J. M.; Beloin, C.; Henry, N.

    2013-12-01

    Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms.

  13. Survival comparison of the Ross procedure and mechanical valve replacement with optimal self-management anticoagulation therapy: propensity-matched cohort study.

    Science.gov (United States)

    Mokhles, M Mostafa; Körtke, Heinrich; Stierle, Ulrich; Wagner, Otto; Charitos, Efstratios I; Bogers, Ad J J C; Gummert, Jan; Sievers, Hans-Hinrich; Takkenberg, Johanna J M

    2011-01-04

    It is suggested that in young adults the Ross procedure results in better late patient survival compared with mechanical prosthesis implantation. We performed a propensity score-matched study that assessed late survival in young adult patients after a Ross procedure versus that after mechanical aortic valve replacement with optimal self-management anticoagulation therapy. We selected 918 Ross patients and 406 mechanical valve patients 18 to 60 years of age without dissection, aneurysm, or mitral valve replacement who survived an elective procedure (1994 to 2008). With the use of propensity score matching, late survival was compared between the 2 groups. Two hundred fifty-three patients with a mechanical valve (mean follow-up, 6.3 years) could be propensity matched to a Ross patient (mean follow-up, 5.1 years). Mean age of the matched cohort was 47.3 years in the Ross procedure group and 48.0 years in the mechanical valve group (P=0.17); the ratio of male to female patients was 3.2 in the Ross procedure group and 2.7 in the mechanical valve group (P=0.46). Linearized all-cause mortality rate was 0.53% per patient-year in the Ross procedure group compared with 0.30% per patient-year in the mechanical valve group (matched hazard ratio, 1.86; 95% confidence interval, 0.58 to 5.91; P=0.32). Late survival was comparable to that of the general German population. In comparable patients, there is no late survival difference in the first postoperative decade between the Ross procedure and mechanical aortic valve implantation with optimal anticoagulation self-management. Survival in these selected young adult patients closely resembles that of the general population, possibly as a result of highly specialized anticoagulation self-management, better timing of surgery, and improved patient selection in recent years.

  14. Retinoic acid-loaded polymeric nanoparticles enhance vascular regulation of neural stem cell survival and differentiation after ischaemia

    Science.gov (United States)

    Ferreira, R.; Fonseca, M. C.; Santos, T.; Sargento-Freitas, J.; Tjeng, R.; Paiva, F.; Castelo-Branco, M.; Ferreira, L. S.; Bernardino, L.

    2016-04-01

    Stroke is one of the leading causes of death and disability worldwide. However, current therapies only reach a small percentage of patients and may cause serious side effects. We propose the therapeutic use of retinoic acid-loaded nanoparticles (RA-NP) to safely and efficiently repair the ischaemic brain by creating a favourable pro-angiogenic environment that enhances neurogenesis and neuronal restitution. Our data showed that RA-NP enhanced endothelial cell proliferation and tubule network formation and protected against ischaemia-induced death. To evaluate the effect of RA-NP on vascular regulation of neural stem cell (NSC) survival and differentiation, endothelial cell-conditioned media (EC-CM) were collected. EC-CM from healthy RA-NP-treated cells reduced NSC death and promoted proliferation while EC-CM from ischaemic RA-NP-treated cells decreased cell death, increased proliferation and neuronal differentiation. In parallel, human endothelial progenitor cells (hEPC), which are part of the endogenous repair response to vascular injury, were collected from ischaemic stroke patients. hEPC treated with RA-NP had significantly higher proliferation, which further highlights the therapeutic potential of this formulation. To conclude, RA-NP protected endothelial cells from ischaemic death and stimulated the release of pro-survival, proliferation-stimulating factors and differentiation cues for NSC. RA-NP were shown to be up to 83-fold more efficient than free RA and to enhance hEPC proliferation. These data serve as a stepping stone to use RA-NP as vasculotrophic and neurogenic agents for vascular disorders and neurodegenerative diseases with compromised vasculature.

  15. Feeding ω-3 PUFA enriched rotifers to Galaxias maculatus (Jenyns, 1842 larvae reared at different salinity conditions: effects on growth parameters, survival and fatty acids profile

    Directory of Open Access Journals (Sweden)

    Patricio Dantagnan

    2013-07-01

    Full Text Available Despite the well known importance of ω-3 polyunsaturated fatty acids (PUFA in marine and freshwater fish larvae, there are few studies on how essential fatty acid requirements and composition on whole body can be altered by changes in water salinity. The present study aimed to determine the effect of salinity on ω-3 PUFA requirements, larval growth survival and fatty acid composition of Galaxias maculatus larvae cultured at two different salinities (0 and 15 g L-1 for 20 days while fed rotifers containing two different levels of ω-3 PUFA (1.87 and 3.16%. The results denoted a marked difference in ω-3 PUFA requirements and in the pattern of fatty acid deposition in the whole body of larvae reared at different salinities, depending of ω-3 PUFA in diets. Thus, to improve growth and survival larvae of G. maculatus reared at 0 g L-1 require higher levels of ω-3 PUFA, principally 18:3 ω-3. Larvae reared at salinities of 15 g L-1 require low levels of ω-3 PUFA for optimal survival, especially 18:3 ω-3. Eicosapentaenoic acid and docosahexaenoic acid content in the whole body of larvae was also affected by water salinity.

  16. Mechanism of acid corrosion inhibition using magnetic nanofluid

    Science.gov (United States)

    Parekh, Kinnari; Jauhari, Smita; Upadhyay, R. V.

    2016-12-01

    The inhibition effect of magnetic nanofluid on carbon steel in acid solutions was investigated using gravimetric, potentiodynamic and SEM measurement. The inhibition efficiency increases up to 95% and 75% for 51.7 mM concentration, respectively, in 1 M HCl and 1 M H2SO4 medium. The adsorption of nanoparticles to the steel surface forms a barrier between the metal and the aggressive environment, which is responsible for observed inhibition action. The adsorption of nanoparticles on steel surface is supported by the Langmuir and Freundlich adsorption isotherm and surface morphology scanned through SEM.

  17. Acetic acid vapor: 2. A statistical mechanical critique of vapor density experiments.

    Science.gov (United States)

    Togeas, James B

    2005-06-23

    A statistical mechanical model is used to critique vapor density experiments on acetic acid. The model suggests that the differences in the standard enthalpy of dissociation of acetic acid dimer reported in the literature lie mainly in the interpretation of the data and not in the data itself. If a uniform and plausible interpretative framework is adopted, the discrepancies largely disappear.

  18. Furanyl Fatty Acid Inhibition of FABP5 as a Mechanism for Treatment and Prevention of Cancer

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-16-1-0699 TITLE: Furanyl Fatty Acid Inhibition of FABP5 as a Mechanism for Treatment and Prevention of Cancer PRINCIPAL...pharmacologic inhibition will prevent the oncogenic effects of FABP5 overexpression in highly relevant breast cancer models that display a high ratio of...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Furanyl Fatty Acid Inhibition of FABP5 as a Mechanism for Treatment and Prevention of

  19. Mechanism of Oxidation of Brilliant Cresyl Blue with Acidic Chlorite ...

    African Journals Online (AJOL)

    NJD

    A Kinetic Approach. Lindelani Qwabe, Brijesh Pare and Sreekanth B. Jonnalagadda*. School of Chemistry, University of KwaZulu-Natal, Westville Campus, Durban, 4000 South Africa. Received 3 December 2004; revised 27 April 2005; accepted 9 June 2005. ABSTRACT. The kinetics and mechanism of oxidation of brilliant ...

  20. A mechanism for hydrochloric acid production in cloud

    Science.gov (United States)

    Glenn K. Yue; Volkar A. Mohnen; C. S. Kiang

    1976-01-01

    A theoretical model describing the general interaction between atmospheric trace gases, such as SO2, NH3, CO2 and O2, chemical reactant gaseous product H2SO4 and hydrometeors containing NaCl is proposed to study a possible mechanism...

  1. Regional chemotherapy of nonresectable colorectal liver metastases with mitoxantrone, 5-fluorouracil, folinic acid, and mitomycin C may prolong survival.

    Science.gov (United States)

    Link, K H; Sunelaitis, E; Kornmann, M; Schatz, M; Gansauge, F; Leder, G; Formentini, A; Staib, L; Pillasch, J; Beger, H G

    2001-12-01

    Regional chemotherapy of isolated, nonresectable colorectal liver metastases (CRLMs) by hepatic artery infusion (HAI) has the advantages of high response rates and the possibility of downstaging and resection of CRLMs. 5-Fluorodeoxyuridine (5-FUDR) has been the drug studied in most Phase II and III trials. The meta-analysis of the Phase III trials comparing HAI with systemic or supportive therapy confirmed an advantage for response and even survival for HAI. Hepatic artery infusion with 5-FUDR, however, is hepatotoxic, inducing sclerosing cholangitis (SC). The authors have introduced 5-fluorouracil (5-FU) with folinic acid for HAI and found equal effectivity but no SC when compared with HAI with 5-FUDR. Now, they report a new combination chemotherapy protocol based on HAI with 5-FU with FA and on in vitro Phase II studies suggesting mitoxantrone and mitomycin C as active drugs for HAI in CRLM. PATIENTS AND METHODS Between February 1993 and August 2000, 63 patients with CRLM were treated with HAI using mitoxantrone, 5-FU with FA, and mitomycin C (MFFM) via port catheters with a protocol planing up to 11 cycles of treatment. Toxicity and response were analyzed according to World Health Organization (WHO) criteria, and survival was analyzed according to Kaplan-Meier. All patients were treated with more than two HAI cycles. The objective response rate (complete remission and partial remission) was 54% and primary intrahepatic progression (progressive disease) occurred in 4.8%, whereas in 41.3% of the patients the intrahepatic disease was evaluated as no change. Median survival times from the first diagnosis of CRLM or start of HAI were 25.7 months and 23.7 months, respectively, and 7 patients lived longer than 40 months. Grade 3 toxicity according to WHO occurred in 34.9%, and Grade 4 occurred in 3.2%. No toxic death or SC occurred. Our new HAI protocol with MFFM seems to be superior to HAI with 5-FUDR, 5-FU with FA, and systemic chemotherapy with 5-FU and FA at

  2. Effect of dietary arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid on survival, growth and pigmentation in larvae of common sole ( Solea solea L.)

    DEFF Research Database (Denmark)

    Lund, Ivar; Steenfeldt, Svend Jørgen; Hansen, B.W.

    2007-01-01

    on Artemia enriched with 10 formulated emulsions, differing in inclusions of ARA, EPA, and DHA. The specific growth rate of the sole larvae until late metamorphosis, 21 days after hatching (dah) was 20 to 27% d(-1). Even though the relative tissue essential fatty acid (EFA) concentrations significantly...... resulted in a lower growth rate, which suggests that visual aberrations affected prey capture. (C) 2007 Elsevier B.V. All rights reserved....

  3. Alcohols enhance the rate of acetic acid diffusion inS. cerevisiae: biophysical mechanisms and implications for acetic acid tolerance.

    Science.gov (United States)

    Lindahl, Lina; Genheden, Samuel; Faria-Oliveira, Fábio; Allard, Stefan; Eriksson, Leif A; Olsson, Lisbeth; Bettiga, Maurizio

    2017-12-01

    Microbial cell factories with the ability to maintain high productivity in the presence of weak organic acids, such as acetic acid, are required in many industrial processes. For example, fermentation media derived from lignocellulosic biomass are rich in acetic acid and other weak acids. The rate of diffusional entry of acetic acid is one parameter determining the ability of microorganisms to tolerance the acid. The present study demonstrates that the rate of acetic acid diffusion in S. cerevisiae is strongly affected by the alcohols ethanol and n-butanol. Ethanol of 40 g/L and n-butanol of 8 g/L both caused a 65% increase in the rate of acetic acid diffusion, and higher alcohol concentrations caused even greater increases. Molecular dynamics simulations of membrane dynamics in the presence of alcohols demonstrated that the partitioning of alcohols to the head group region of the lipid bilayer causes a considerable increase in the membrane area, together with reduced membrane thickness and lipid order. These changes in physiochemical membrane properties lead to an increased number of water molecules in the membrane interior, providing biophysical mechanisms for the alcohol-induced increase in acetic acid diffusion rate. n-butanol affected S. cerevisiae and the cell membrane properties at lower concentrations than ethanol, due to greater and deeper partitioning in the membrane. This study demonstrates that the rate of acetic acid diffusion can be strongly affected by compounds that partition into the cell membrane, and highlights the need for considering interaction effects between compounds in the design of microbial processes.

  4. Alcohols enhance the rate of acetic acid diffusion in S. cerevisiae: biophysical mechanisms and implications for acetic acid tolerance

    Science.gov (United States)

    Lindahl, Lina; Genheden, Samuel; Faria-Oliveira, Fábio; Allard, Stefan; Eriksson, Leif A.; Olsson, Lisbeth; Bettiga, Maurizio

    2017-01-01

    Microbial cell factories with the ability to maintain high productivity in the presence of weak organic acids, such as acetic acid, are required in many industrial processes. For example, fermentation media derived from lignocellulosic biomass are rich in acetic acid and other weak acids. The rate of diffusional entry of acetic acid is one parameter determining the ability of microorganisms to tolerance the acid. The present study demonstrates that the rate of acetic acid diffusion in S. cerevisiae is strongly affected by the alcohols ethanol and n-butanol. Ethanol of 40 g/L and n-butanol of 8 g/L both caused a 65% increase in the rate of acetic acid diffusion, and higher alcohol concentrations caused even greater increases. Molecular dynamics simulations of membrane dynamics in the presence of alcohols demonstrated that the partitioning of alcohols to the head group region of the lipid bilayer causes a considerable increase in the membrane area, together with reduced membrane thickness and lipid order. These changes in physiochemical membrane properties lead to an increased number of water molecules in the membrane interior, providing biophysical mechanisms for the alcohol-induced increase in acetic acid diffusion rate. n-butanol affected S. cerevisiae and the cell membrane properties at lower concentrations than ethanol, due to greater and deeper partitioning in the membrane. This study demonstrates that the rate of acetic acid diffusion can be strongly affected by compounds that partition into the cell membrane, and highlights the need for considering interaction effects between compounds in the design of microbial processes. PMID:29354649

  5. Genome-Wide Transposon Mutagenesis Indicates that Mycobacterium marinum Customizes Its Virulence Mechanisms for Survival and Replication in Different Hosts

    KAUST Repository

    Weerdenburg, Eveline M.

    2015-02-17

    The interaction of environmental bacteria with unicellular eukaryotes is generally considered a major driving force for the evolution of intracellular pathogens, allowing them to survive and replicate in phagocytic cells of vertebrate hosts. To test this hypothesis on a genome-wide level, we determined for the intracellular pathogen Mycobacterium marinum whether it uses conserved strategies to exploit host cells from both protozoan and vertebrate origin. Using transposon-directed insertion site sequencing (TraDIS), we determined differences in genetic requirements for survival and replication in phagocytic cells of organisms from different kingdoms. In line with the general hypothesis, we identified a number of general virulence mechanisms, including the type VII protein secretion system ESX-1, biosynthesis of polyketide lipids, and utilization of sterols. However, we were also able to show that M. marinum contains an even larger set of host-specific virulence determinants, including proteins involved in the modification of surface glycolipids and, surprisingly, the auxiliary proteins of the ESX-1 system. Several of these factors were in fact counterproductive in other hosts. Therefore, M. marinum contains different sets of virulence factors that are tailored for specific hosts. Our data imply that although amoebae could function as a training ground for intracellular pathogens, they do not fully prepare pathogens for crossing species barriers.

  6. Fermentation conditions influence the fatty acid composition of the membranes of Lactobacillus reuteri I5007 and its survival following freeze-drying.

    Science.gov (United States)

    Liu, X T; Hou, C L; Zhang, J; Zeng, X F; Qiao, S Y

    2014-10-01

    Lactobacillus reuteri I5007 has well-documented adhesion properties and health benefits. Future industrial use of Lact. reuteri I5007 will require the development of effective fermentation procedures and high bacterial survival following drying. Therefore, this study was conducted to determine the impact of altering fermentation pH and temperature on the fatty acid composition of the bacterial membranes and subsequent survival of Lact. reuteri I5007 following freeze-drying. Initially, a response surface methodology was used to determine the optimal fermentation pH (5·7) and temperature (37°C), with regard to producing the maximum number of Lact. reuteti I5007 cells. However, when subjected to the optimal fermentation pH and temperature (control treatment), the subsequent survival of Lact. reuteri I5007 following freeze-drying was only 12·95%. Growth at a higher temperature (47°C) or at a neutral pH (pH 6·7) significantly increased the survival of Lact. reuteri I5007 following freeze-drying compared with the control. In contrast, an acidic pH (pH 4·7), or cold (27°C) and extremely cold (4°C) temperatures during fermentation significantly reduced Lact. reuteri I5007 survival following freeze-drying. The fatty acid composition of the membranes of Lact. reuteri I5007 was altered by the different fermentation conditions tested. An increase in the ratio of unsaturated fatty acids (UFA) to saturated fatty acids (SFA) in the bacterial membrane was associated with higher survival of Lact. reuteri I5007. In conclusion, it appears that the use of a higher temperature (47°C) or neutral pH (6·7) during fermentation resulted in increased survival of Lact. reuteri I5007 following freeze-drying. Significance and impact of the study: In this study, we found that a higher fermentation temperature or a neutral pH, rather than cold or acidic conditions, leads to increased survival of Lact. reuteri I5007 during subsequent freeze-drying. This finding has important implications

  7. [Influencing factors and reaction mechanism of chloroacetic acid reduction by cast iron].

    Science.gov (United States)

    Tang, Shun; Yang, Hong-Wei; Wang, Xiao-Mao; Xie, Yue-Feng

    2014-03-01

    The chloroacetic acids are ubiquitous present as a class of trace chlorinated organic pollutants in surface and drinking water. Most of chloroacetic acids are known or suspected carcinogens and, when at high concentrations, are of great concern to human health. In order to economically remove chloroacetic acids, the degradation of chloroacetic acids by cast iron was investigated. Moreover, the effect of iron style, pretreatment process, shocking mode and dissolved oxygen on chloroacetic acids reduced by cast iron was discussed. Compared to iron source and acid pretreatment, mass transfer was more important to chloroacetic acid removal. Dichloroacetic acid (DCAA) and monochloroacetic acid (MCAA) were the main products of anoxic and oxic degradation of trichloroacetic acid (TCAA) by cast iron during the researched reaction time, respectively. With longtitudinal shock, the reaction kinetics of chloroaectic acid removal by cast iron conformed well to the pseudo first order reaction. The anoxic reaction constants of TCAA, DCAA and MCAA were 0.46 h(-1), 0.03 h(-1) and 0, and their oxic constants were 1.24 h(-1), 0.79 h(-1) and 0.28 h(-1), respectively. The removal mechanisms of chloroacetic acids were different under various oxygen concentrations, including sequential hydrogenolysis for anoxic reaction and sequential hydrogenolysis and direct transformation possible for oxic reaction, respectively.

  8. Naturally occurring and stress induced tubular structures from mammalian cells, a survival mechanism

    Directory of Open Access Journals (Sweden)

    He Jian

    2007-08-01

    Full Text Available Abstract Background Tubular shaped mammalian cells in response to dehydration have not been previously reported. This may be due to the invisibility of these cells in aqueous solution, and because sugars and salts added to the cell culture for manipulation of the osmotic conditions inhibit transformation of normal cells into tubular shaped structures. Results We report the transformation of normal spherical mammalian cells into tubular shaped structures in response to stress. We have termed these transformed structures 'straw cells' which we have associated with a variety of human tissue types, including fresh, post mortem and frozen lung, liver, skin, and heart. We have also documented the presence of straw cells in bovine brain and prostate tissues of mice. The number of straw cells in heart, lung tissues, and collapsed straw cells in urine increases with the age of the mammal. Straw cells were also reproduced in vitro from human cancer cells (THP1, CACO2, and MCF7 and mouse stem cells (D1 and adipose D1 by dehydrating cultured cells. The tubular center of the straw cells is much smaller than the original cell; houses condensed organelles and have filamentous extensions that are covered with microscopic hair-like structures and circular openings. When rehydrated, the filaments uptake water rapidly. The straw cell walls, have a range of 120 nm to 200 nm and are composed of sulfated-glucose polymers and glycosylated acidic proteins. The transformation from normal cell to straw cells takes 5 to 8 hr in open-air. This process is characterized by an increase in metabolic activity. When rehydrated, the straw cells regain their normal spherical shape and begin to divide in 10 to 15 days. Like various types of microbial spores, straw cells are resistant to harsh environmental conditions such as UV-C radiation. Conclusion Straw cells are specialized cellular structures and not artifacts from spontaneous polymerization, which are generated in response

  9. Nonlinear Kinetics and Mechanism of Nile Blue Reaction with Acidic ...

    African Journals Online (AJOL)

    After an induction period, a swift reaction occurs. The overall reaction is NB+ + BrO3- react to P + CH3COOH + H+ + Br-, where P is the de-ethylated N-oxide derivative of nile blue. The rapid kinetics of the reaction of bromine direct with nile blue were also reported. A 11-step mechanism, consistent with the overall reaction ...

  10. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures.

    Science.gov (United States)

    Shim, Hye Won; Yang, Byoung-Eun

    2015-12-01

    To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos® implants. This was a retrospective clinical study that analyzed 450 single Ankylos® implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position. The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all Ptooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.

  11. Aquatic respiration as a potential survival mechanism of Brephidium pseudofea (Lepidoptera: Lycaenidae) larvae to intertidal environments.

    Science.gov (United States)

    Warren, V; Daniels, J C; Hahn, D A

    2011-10-01

    The eastern pygmy blue, Brephidium pseudofea (Morrison) (Lepidoptera: Lycaenidae: Polyommatinae), inhabits intertidal environments that are periodically flooded. The immature stages are subject to salt or brackish water inundation during this time and therefore must endure many stressors, including respiratory limitation and salt exposure. Our goal was to investigate possible mechanisms used by the larval stages of B. pseudofea to endure periodic tidal inundation by using physiological and morphological analyses in comparison with several species of terrestrial lepidopteran larvae. A review of tidal charts showed that the immature stages of B. pseudofea would be prone to complete inundation two to five times per month during the summer months (May to August) and partial submersion for up to 20 d per month during the rest of the year. Larvae of several terrestrial lepidopteran species studied consumed oxygen under water for a limited period, but B. pseudofea demonstrated substantially higher oxygen consumption. Light microscopy of B. pseudofea larvae revealed small air pockets in and around the spiracles when submerged in tap water; these air pockets disappeared when exposed to detergent solution. The resulting air pockets may function as a diffusion layer for oxygen to be absorbed from the surrounding water or may act in conjunction with trans-cuticular gas exchange to meet the larva's respiratory needs. Morphological examination by scanning electron microscopy showed that B. psudofea larvae have distinctively small, clavate setae that appear insufficient to effectively support a functional plastron.

  12. Saccharomyces cerevisiae EC-1118 enhances the survivability of probiotic Lactobacillus rhamnosus HN001 in an acidic environment.

    Science.gov (United States)

    Lim, Phebe Lixuan; Toh, Mingzhan; Liu, Shao Quan

    2015-08-01

    The present study attempted to partially characterize and elucidate the viability-enhancing effect of a yeast strain Saccharomyces cerevisiae EC-1118 on a probiotic strain Lactobacillus rhamnosus HN001 under acidic conditions using a model system (non-growing cells). The yeast was found to significantly enhance (P viability of the probiotic strain under acidic conditions (pH 2.5 to 4.0) by 2 to 4 log cycles, and the viability-enhancing effects were observed to be influenced by pH, and probiotic and yeast concentrations. Microscopic observation and co-aggregation assay revealed that the viability-enhancing effect of the yeast could be attributed to direct cell-cell contact co-aggregation mediated by yeast cell surface and/or cell wall components or metabolites. Furthermore, non-viable yeast cells killed by thermal means were observed to enhance the viability of the probiotic strain as well, suggesting that the surface and/or cell wall component(s) of the yeast contributing to co-aggregation was heat-stable. Cell-free yeast supernatant was also found to enhance the viability of the probiotic strain, indicating the presence of protective yeast metabolite(s) in the supernatant. These findings laid the foundation for further understanding of the mechanism(s) involved and for developing novel microbial starter cultures possibly without the use of live yeast for ambient-stable high-moisture probiotic foods.

  13. Adipic acid degradation mechanism in aqueous fgd (flue gas desulfurization) systems. Final report Oct 78-Apr 79

    Energy Technology Data Exchange (ETDEWEB)

    Meserole, F.B.; Lewis, D.L.; Nichols, A.W.; Rochelle, G.

    1979-09-01

    The report gives results of a field and laboratory study of the adipic acid degradation mechanism in aqueous flue gas desulfurization (FGD) systems. (Adding adipic acid to limestone-based, SO2 wet scrubbers increases SO2 removal and limestone utilization. However, as much as 80% of the adipic acid added to some systems is lost, supposedly through degradation.) The degradation is associated with the oxidation of sulfite, possibly through a free radical mechanism. At least one mechanism is an oxidative decarboxylation yielding valeric acid, butyric acid, glutaric acid, and CO2. The quantities of products measured during laboratory testing only account for approximately 30% of the adipic acid degraded.

  14. Quality attributes and microbial survival on whole cantaloupes with antimicrobial coatings containing chitosan, lauric arginate, cinnamon oil and ethylenediaminetetraacetic acid.

    Science.gov (United States)

    Ma, Qiumin; Zhang, Yue; Critzer, Faith; Davidson, P Michael; Zhong, Qixin

    2016-10-17

    Cantaloupes are susceptible to microbiological contamination in pre- or postharvest environments. Novel intervention strategies, such as antimicrobial coatings, are needed to improve the microbiological safety of cantaloupes. The objective of this study was to prepare whole cantaloupes coated with mixtures containing chitosan, lauric arginate (LAE), cinnamon oil (CO), and ethylenediaminetetraacetic acid (EDTA) and determine survival characteristics of inoculated foodborne pathogens during storage as well as cantaloupe quality attributes. Chitosan coating with 0.1% LAE, 0.1% EDTA, and 1% CO was the most effective for inactivating foodborne pathogens inoculated on cantaloupes. This coating caused a >3logCFU/cm(2) reduction of Escherichia coli O157:H7 and Listeria monocytogenes immediately after coating and reduced Salmonella enterica to below the detection limit during a 14-day storage. Total molds and yeasts also were reduced to the detection limit by the coating. The redness and yellowness of uncoated cantaloupes were significantly higher than coated ones from day 6. The firmness of uncoated cantaloupes and those coated with chitosan only was significantly lower than other treatments from day 10. No significant differences were found in total soluble solids content or weight loss between coated and uncoated cantaloupes. Results showed the potential benefits of applying the coating mixtures to improve the quality and microbiological safety of cantaloupes. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. RISK OF REPEATED THROMBOTIC EVENTS IN PATIENTS SURVIVED ACUTE CORONARY SYNDROME AND HAVING LABORATORY PROVEN RESISTANCE TO ACETYLSALICYLIC ACID

    Directory of Open Access Journals (Sweden)

    N. F. Puchinyan

    2009-01-01

    Full Text Available Aim. To evaluate risk of repeated atherothrombotic events in patients survived acute coronary syndrome (ACS and having poorly reduced platelet aggregation (proven by optical aggregometry in response to acetylsalicylic acid (ASA therapy.Material and methods. 200 patients with ACS (aged 56,6±9,2 y.o. were included in the study. Platelet functional activity during ASA therapy was evaluated with laser aggregometer. ASA resistance was defined if the summarizing index of platelet aggregation (induced with ADP, 5 mμml/l was 50% or higher during ASA therapy. Observation period was 18±6 months. Atherothrombotic events (unstable angina, myocardial infarction, stroke, cardiovascular death were considered.Results. Lack ASA response rate was about 12%. Totally 22 repeated atherothrombotic events were registered: 5,6% among ASA sensitive patients and 50% - among ASA resistant patients. Repeated atherothrombotic events were registered in ASA resistance patients during first 14 days. ASA sensitive patients showed repeated atherothrombotic events in some months after ACS. The relative risk of cardiovascular event in ASA resistance patients was 8,92 (CI 95% 4,39; 17,84 р=0,05.Conclusion. The high level of the induced platelet aggregation (proven by laser aggregometry points to high risk of repeated atherothrombotic events in patients with ACS.

  16. Mechanism of biosynthesis of unsaturated fatty acids in Pseudomonas sp. strain E-3, a psychrotrophic bacterium

    Energy Technology Data Exchange (ETDEWEB)

    Wada, M.; Fukunaga, N.; Sasaki, S. (Hokkaido Univ., Sapporo (Japan))

    1989-08-01

    Biosynthesis of palmitic, palmitoleic, and cis-vaccenic acids in Pseudomonas sp. strain E-3 was investigated with in vitro and in vivo systems. (1-{sup 14}C)palmitic acid was aerobically converted to palmitoleate and cis-vaccenate, and the radioactivities on their carboxyl carbons were 100 and 43%, respectively, of the total radioactivity in the fatty acids. Palmitoyl coenzyme A desaturase activity was found in the membrane fraction. (1-{sup 14}C)stearic acid was converted to octadecenoate and C16 fatty acids. The octadecenoate contained oleate and cis-vaccenate, but only oleate was produced in the presence of cerulenin. (1-{sup 14}C)lauric acid was aerobically converted to palmitate, palmitoleate, and cis-vaccenate. Under anaerobic conditions, palmitate (62%), palmitoleate (4%), and cis-vaccenate (34%) were produced from (1-{sup 14}C)acetic acid, while they amounted to 48, 39, and 14%, respectively, under aerobic conditions. In these incorporation experiments, 3 to 19% of the added radioactivity was detected in released {sup 14}CO{sub 2}, indicating that part of the added fatty acids were oxidatively decomposed. Partially purified fatty acid synthetase produced saturated and unsaturated fatty acids with chain lengths of C10 to C18. These results indicated that both aerobic and anaerobic mechanisms for the synthesis of unsaturated fatty acid are operating in this bacterium.

  17. Influence of marinades on survival during storage of acid-adapted and nonadapted Listeria monocytogenes inoculated post-drying on beef jerky.

    Science.gov (United States)

    Calicioglu, Mehmet; Sofos, John N; Kendall, Patricia A

    2003-09-15

    The objective of the present study was to investigate the survival of acid-adapted and nonadapted Listeria monocytogenes inoculated post-drying on dried beef slices (beef jerky), which were treated (24 h, 4 degrees C) with the following marinades before drying at 60 degrees C for 10 h: (1) control (C), (2) traditional marinade (TM), (3) modified marinade; double the amount of TM with added 1.2% sodium lactate, 9% acetic acid, and 68% soy sauce with 5% ethanol (MM), (4) dipping into 5% acetic acid and then TM (AATM), and (5) dipping into 1% Tween 20 and then into 5% acetic acid followed by the TM (TWTM). Dried meat slices were inoculated with acid-adapted or nonadapted L. monocytogenes (ca. 5.7 log CFU/cm(2)) prior to aerobic storage at 25 degrees C for 60 days. Survivors were determined using tryptic soy agar with 0.1% pyruvate (TSAP) and PALCAM agar. Results showed that surviving bacterial populations on TWTM, AATM, and MM treatments were significantly (P or =0.05) difference in survival of previously acid-adapted and nonadapted bacterial populations in samples of TWTM, AATM, and MM treatments. However, bacterial populations that were nonadapted were significantly higher than those that were acid-adapted on products of C and TM treatments on days 60 and 24, respectively. The earliest complete elimination (enrichment negative) of the pathogen occurred by day 28 (AATM) in products inoculated with acid-adapted cultures and by day 42 (TWTM and AATM) in products inoculated with nonadapted cultures. These results indicate that use of modified marinades in jerky processing and low water activity provided antimicrobial effects against possible post-processing contamination with L. monocytogenes.

  18. Deoxyribonucleic Acid Damage and Repair: Capitalizing on Our Understanding of the Mechanisms of Maintaining Genomic Integrity for Therapeutic Purposes

    Directory of Open Access Journals (Sweden)

    Jolene Michelle Helena

    2018-04-01

    Full Text Available Deoxyribonucleic acid (DNA is the self-replicating hereditary material that provides a blueprint which, in collaboration with environmental influences, produces a structural and functional phenotype. As DNA coordinates and directs differentiation, growth, survival, and reproduction, it is responsible for life and the continuation of our species. Genome integrity requires the maintenance of DNA stability for the correct preservation of genetic information. This is facilitated by accurate DNA replication and precise DNA repair. DNA damage may arise from a wide range of both endogenous and exogenous sources but may be repaired through highly specific mechanisms. The most common mechanisms include mismatch, base excision, nucleotide excision, and double-strand DNA (dsDNA break repair. Concurrent with regulation of the cell cycle, these mechanisms are precisely executed to ensure full restoration of damaged DNA. Failure or inaccuracy in DNA repair contributes to genome instability and loss of genetic information which may lead to mutations resulting in disease or loss of life. A detailed understanding of the mechanisms of DNA damage and its repair provides insight into disease pathogeneses and may facilitate diagnosis and the development of targeted therapies.

  19. Heterogeneous kinetics, products, and mechanisms of ferulic acid particles in the reaction with NO3 radicals

    Science.gov (United States)

    Liu, Changgeng; Zhang, Peng; Wen, Xiaoying; Wu, Bin

    2017-03-01

    Methoxyphenols, as an important component of wood burning, are produced by lignin pyrolysis and considered to be the potential tracers for wood smoke emissions. In this work, the heterogeneous reaction between ferulic acid particles and NO3 radicals was investigated. Six products including oxalic acid, 4-vinylguaiacol, vanillin, 5-nitrovanillin, 5-nitroferulic acid, and caffeic acid were confirmed by gas chromatography-mass spectrometry (GC-MS). In addition, the reaction mechanisms were proposed and the main pathways were NO3 electrophilic addition to olefin and the meta-position to the hydroxyl group. The uptake coefficient of NO3 radicals on ferulic acid particles was 0.17 ± 0.02 and the effective rate constant under experimental conditions was (1.71 ± 0.08) × 10-12 cm3 molecule-1 s-1. The results indicate that ferulic acid degradation by NO3 can be an important sink at night.

  20. Mechanism-based pharmacokinetic-pharmacodynamic modeling of salvianolic acid A effects on plasma xanthine oxidase activity and uric acid levels in acute myocardial infarction rats.

    Science.gov (United States)

    Wang, Haidong; Li, Xi; Zhang, Wenting; Liu, Yao; Wang, Shijun; Liu, Xiaoquan; He, Hua

    2017-03-01

    1. Salvianolic acid A (SalA) was found to attenuate plasma uric acid (UA) concentration and xanthine oxidase (XO) activity in acute myocardial infraction (AMI) rats, which was characterized with developed mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) model. 2. AMI was induced in rats by coronary artery ligation. Surviving AMI rats received a single intravenous dose of 5 mg/kg of SalA and normal saline. The plasma SalA concentrations were determined by HPLC-MS/MS method. The plasma UA concentrations were determined by HPLC method and plasma XO activity were measured spectrophotometrically. An integrated mathematical model characterized the relationship between plasma UA and SalA. 3. Pharmacokinetics was described using two-compartment model for SalA with linear metabolic process. In post-AMI rats, XO activity and UA concentrations were increased, while SalA dosing palliated this increase. These effects were well captured by using two series of transduction models, simulating the delay of inhibition on XO driven by SalA and UA elevation resulted from the multiple factors, respectively. 4. The effect was well described by the developed PK-PD model, indicating that SalA can exert cardiovascular protective effects by decreasing elevated plasma UA levels induced by AMI.

  1. TRPV6 calcium channel translocates to the plasma membrane via Orai1-mediated mechanism and controls cancer cell survival.

    Science.gov (United States)

    Raphaël, Maylis; Lehen'kyi, V'yacheslav; Vandenberghe, Matthieu; Beck, Benjamin; Khalimonchyk, Sergiy; Vanden Abeele, Fabien; Farsetti, Leonardo; Germain, Emmanuelle; Bokhobza, Alexandre; Mihalache, Adriana; Gosset, Pierre; Romanin, Christoph; Clézardin, Philippe; Skryma, Roman; Prevarskaya, Natalia

    2014-09-16

    Transient receptor potential vanilloid subfamily member 6 (TRPV6) is a highly selective calcium channel that has been considered as a part of store-operated calcium entry (SOCE). Despite its first discovery in the early 2000s, the role of this channel in prostate cancer (PCa) remained, until now, obscure. Here we show that TRPV6 mediates calcium entry, which is highly increased in PCa due to the remodeling mechanism involving the translocation of the TRPV6 channel to the plasma membrane via the Orai1/TRPC1-mediated Ca(2+)/Annexin I/S100A11 pathway, partially contributing to SOCE. The TRPV6 calcium channel is expressed de novo by the PCa cell to increase its survival by enhancing proliferation and conferring apoptosis resistance. Xenografts in nude mice and bone metastasis models confirmed the remarkable aggressiveness of TRPV6-overexpressing tumors. Immunohistochemical analysis of these demonstrated the increased expression of clinical markers such as Ki-67, prostate specific antigen, synaptophysin, CD31, and CD56, which are strongly associated with a poor prognosis. Thus, the TRPV6 channel acquires its oncogenic potential in PCa due to the remodeling mechanism via the Orai1-mediated Ca(2+)/Annexin I/S100A11 pathway.

  2. Use of Gallic Acid to Enhance the Antioxidant and Mechanical Properties of Active Fish Gelatin Film.

    Science.gov (United States)

    Limpisophon, Kanokrat; Schleining, Gerhard

    2017-01-01

    This study explores the potential roles of gallic acid in fish gelatin film for improving mechanical properties, UV barrier, and providing antioxidant activities. Glycerol, a common used plasticizer, also impacts on mechanical properties of the film. A factorial design was used to investigate the effects of gallic acid and glycerol concentrations on antioxidant activities and mechanical properties of fish gelatin film. Increasing the amount of gallic acid increased the antioxidant capacities of the film measured by radical scavenging assay and the ferric reducing ability of plasma assay. The released antioxidant power of gallic acid from the film was not reduced by glycerol. The presence of gallic acid not only increased the antioxidant capacity of the film, but also increased the tensile strength, elongation at break, and reduced UV absorption due to interaction between gallic acid and protein by hydrogen bonding. Glycerol did not affect the antioxidant capacities of the film, but increased the elasticity of the films. Overall, this study revealed that gallic acid entrapped in the fish gelatin film provided antioxidant activities and improved film characteristics, namely UV barrier, strength, and elasticity of the film. © 2016 Institute of Food Technologists®.

  3. Expression of Ski can act as a negative feedback mechanism on retinoic acid signaling.

    Science.gov (United States)

    Melling, Meaghan A; Friendship, Charlotte R C; Shepherd, Trevor G; Drysdale, Thomas A

    2013-06-01

    Retinoic acid signaling is essential for many aspects of early development in vertebrates. To control the levels of signaling, several retinoic acid target genes have been identified that act to suppress retinoic acid signaling in a negative feedback loop. The nuclear protein Ski has been extensively studied for its ability to suppress transforming growth factor-beta (TGF-β) signaling but has also been implicated in the repression of retinoic acid signaling. We demonstrate that ski expression is up-regulated in response to retinoic acid in both early Xenopus embryos and in human cell lines. Blocking retinoic acid signaling using a retinoic acid antagonist results in a corresponding decrease in the levels of ski mRNA. Finally, overexpression of SKI in human cells results in reduced levels of CYP26A1 mRNA, a known target of retinoic acid signaling. Our results, coupled with the known ability of Ski to repress retinoic acid signaling, demonstrate that Ski expression is a novel negative feedback mechanism acting on retinoic acid signaling. Copyright © 2013 Wiley Periodicals, Inc.

  4. Effect of pH in the survival of Lactobacillus salivarius strain UCO_979C wild type and the pH acid acclimated variant

    OpenAIRE

    Sanhueza, Enrique; Paredes-Osses, Esteban; González, Carlos L.; García, Apolinaria

    2015-01-01

    Background: Bacterial acclimation involves cellular changes permitting the survival of a microorganism to prolonged acid pH exposure. The general aim of this work is to support this idea by determining the effect of pH in the survival of the human gastric derived probiotic strain Lactobacillus salivarius UCO_979C-1 (wild type) and L. salivarius UCO_979C-2 (acclimation to pH 2.6), which possesses anti-Helicobacter pylori properties. Results: To assess this aim, the exopolysaccharide product...

  5. Effects of Amoxicillin and Clavulanic Acid on the Spontaneous Mechanical Activity of Juvenile Rat Duodenum.

    Science.gov (United States)

    Ciciora, Steven L; Williams, Kent C; Gariepy, Cheryl E

    2015-09-01

    There are a limited number of medications for the treatment of foregut dysmotility. Enteral amoxicillin/clavulanic acid induces phase III duodenal contractions in a fasting pediatric patient. The mechanism by which this occurs is unknown. We examined the individual contributions of amoxicillin and clavulanic acid on the spontaneous mechanical activity of juvenile rat duodenum to better understand this phenomenon. Duodenal segments from juvenile rats were longitudinally attached to force transducers in organ baths. Samples were cumulatively exposed to amoxicillin or clavulanic acid. Separate samples were exposed to carbachol alone to assess response in both the presence and absence of amoxicillin or clavulanic acid. Basal tone, frequency, and amplitude of contractions were digitized and recorded. The amplitude of the spontaneous contractions increased with amoxicillin. Inhibition of neuronal activity prevented this effect. Clavulanic acid did not affect the spontaneous contractions. Basal tone and the rate of contractions did not differ with either drug. Stimulation with carbachol in the presence of amoxicillin caused a statistically significant increase in the contractility compared with carbachol alone. Amoxicillin alters the spontaneous longitudinal mechanical activity of juvenile rat duodenum. Our results suggest that amoxicillin modulates the spontaneous pattern of cyclic mechanical activity of duodenal smooth muscle through noncholinergic, neurally mediated mechanisms. Our work provides an initial physiologic basis for the therapeutic use of amoxicillin in patients with gastrointestinal dysmotility.

  6. Physicochemical and Mechanical Properties of Bambara Groundnut Starch Films Modified with Stearic Acid.

    Science.gov (United States)

    Oyeyinka, Samson A; Singh, Suren; Amonsou, Eric O

    2017-01-01

    The physicochemical and mechanical properties of biofilm prepared from bambara starch modified with varying concentrations of stearic acid (0%, 2.5%, 3.5%, 5%, 7%, and 10%) were studied. By scanning electron microscopy, bambara starch films modified with stearic acid (≥3.5%) showed a progressively rough surface compared to those with 2.5% stearic acid and the control. Fourier transform infrared spectroscopy spectra revealed a peak shift of approximately 31 cm -1 , suggesting the promotion of hydrogen bond formation between hydroxyl groups of starch and stearic acid. The addition of 2.5% stearic acid to bambara starch film reduced water vapor permeability by approximately 17%. Bambara starch films modified with higher concentration of stearic acid were more opaque and showed significantly high melting temperatures. However, mechanical properties of starch films were generally negatively affected by stearic acid. Bambara starch film may be modified with 2.5% stearic acid for improved water vapor permeability and thermal stability with minimal effect on tensile strength. © 2016 Institute of Food Technologists®.

  7. Addition of L-ascorbic acid to culture and vitrification media of IVF porcine blastocysts improves survival and reduces HSPA1A levels of vitrified embryos.

    Science.gov (United States)

    Castillo-Martín, Miriam; Yeste, Marc; Soler, Albert; Morató, Roser; Bonet, Sergi

    2015-09-01

    The aim of the present study was to determine the effect of L-ascorbic acid on embryo quality and gene expression of porcine blastocysts after supplementations of in vitro culture medium and/or vitrification-warming media. Embryo quality, in terms of total cell number (TCN), DNA fragmentation and peroxide levels, together with the relative transcript abundance of BCL-2 associated X protein (BAX), BCL2-like 1 (BCL2L1), POU class 5 homeobox 1 (POU5F1) and heat shock protein 70 (HSPA1A), was analysed. In Experiment 1, gene expression and embryo quality of fresh blastocysts were evaluated after culture with or without L-ascorbic acid; no significant differences were observed between the groups. In Experiment 2, blastocysts cultured with or without L-ascorbic acid were vitrified using two different vitrification solutions, supplemented or not with L-ascorbic acid. Supplementation of culture and vitrification media significantly enhanced survival rates and reduced peroxide levels. No significant differences in TCN, DNA fragmentation and BAX, BCL2L1 and POU5F1 expression were found in vitrified blastocysts among experimental groups. Vitrification procedures increase HSPA1A transcript abundance, but this increase was significantly lower in embryos cultured and/or vitrified with L-ascorbic acid. Thus, supplementing culture and/or vitrification media with L-ascorbic acid enhances survival rates of porcine blastocysts, suggesting a relationship with HSPA1A expression.

  8. Adsorption mechanism of 2,4-dichlorophenoxyacetic acid onto nitric-acid-modified activated carbon fiber.

    Science.gov (United States)

    Li, Qun; Sun, Jie; Ren, Tianhao; Guo, Lin; Yang, Zhilin; Yang, Qi; Chen, Hai

    2018-04-01

    Adsorption by carbon materials is one of the relatively fast methods in present research, which is widely used in emergency events. Activated carbon fiber (ACF) modified by nitric acid (N-ACF) was studied in this research to determine the adsorption performance for 2,4-dichlorophenoxyacetic acid (2,4-D). Subsequently, influence factors, adsorption isotherm models, kinetics and thermodynamic were investigated in a batch system to realize this adsorption. Experimental results showed that ACF modified by 0.1M nitric acid had a better removal ability than 2,4-D. Removal rate of 2,4-D by N-ACF was greatly influenced by pH with the optimum pH at 2. The superiority of the Langmuir isotherm model in describing the adsorption equilibrium was revealed by correlation coefficients R2 (R 2  ≥ 0.997). Furthermore, adsorption kinetics was well described by pseudo-second-order model. The results of thermodynamic showed that adsorption was a spontaneous, endothermic process with randomness increasing. Additionally, surface structure properties of adsorbent were characterized by Scanning electron microscopy, Fourier transform infrared spectroscopy, Specific surface area analysis of Brunauer, Emmett and Teller and Boehm's titration. It turned out that the micropore structure and functional groups on N-ACF all can contribute to the removal of 2,4-D.

  9. Properties of nanocellulose isolated from corncob residue using sulfuric acid, formic acid, oxidative and mechanical methods.

    Science.gov (United States)

    Liu, Chao; Li, Bin; Du, Haishun; Lv, Dong; Zhang, Yuedong; Yu, Guang; Mu, Xindong; Peng, Hui

    2016-10-20

    In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized lignocellulose waste from furfural industry, using four different methods (i.e. sulfuric acid hydrolysis, formic acid (FA) hydrolysis, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and pulp refining, respectively). The self-assembled structure, morphology, dimension, crystallinity, chemical structure and thermal stability of prepared nanocellulose were investigated. FA hydrolysis produced longer cellulose nanocrystals (CNCs) than the one obtained by sulfuric acid hydrolysis, and resulted in high crystallinity and thermal stability due to its preferential degradation of amorphous cellulose and lignin. The cellulose nanofibrils (CNFs) with fine and individualized structure could be isolated by TEMPO-mediated oxidation. In comparison with other nanocellulose products, the intensive pulp refining led to the CNFs with the longest length and the thickest diameter. This comparative study can help to provide an insight into the utilization of CCR as a potential source for nanocellulose production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Abscisic Acid Determines Basal Susceptibility of Tomato to Botrytis cinerea and Suppresses Salicylic Acid-Dependent Signaling Mechanisms1

    Science.gov (United States)

    Audenaert, Kris; De Meyer, Geert B.; Höfte, Monica M.

    2002-01-01

    Abscisic acid (ABA) is one of the plant hormones involved in the interaction between plants and pathogens. In this work, we show that tomato (Lycopersicon esculentum Mill. cv Moneymaker) mutants with reduced ABA levels (sitiens plants) are much more resistant to the necrotrophic fungus Botrytis cinerea than wild-type (WT) plants. Exogenous application of ABA restored susceptibility to B. cinerea in sitiens plants and increased susceptibility in WT plants. These results indicate that ABA plays a major role in the susceptibility of tomato to B. cinerea. ABA appeared to interact with a functional plant defense response against B. cinerea. Experiments with transgenic NahG tomato plants and benzo(1,2,3)thiadiazole-7-carbothioic acid demonstrated the importance of salicylic acid in the tomato-B. cinerea interaction. In addition, upon infection with B. cinerea, sitiens plants showed a clear increase in phenylalanine ammonia lyase activity, which was not observed in infected WT plants, indicating that the ABA levels in healthy WT tomato plants partly repress phenylalanine ammonia lyase activity. In addition, sitiens plants became more sensitive to benzo(1,2,3)thiadiazole-7-carbothioic acid root treatment. The threshold values for PR1a gene expression declined with a factor 10 to 100 in sitiens compared with WT plants. Thus, ABA appears to negatively modulate the salicylic acid-dependent defense pathway in tomato, which may be one of the mechanisms by which ABA levels determine susceptibility to B. cinerea. PMID:11842153

  11. Mechanisms underlying skeletal muscle insulin resistance induced by fatty acids: importance of the mitochondrial function

    Directory of Open Access Journals (Sweden)

    Martins Amanda R

    2012-02-01

    Full Text Available Abstract Insulin resistance condition is associated to the development of several syndromes, such as obesity, type 2 diabetes mellitus and metabolic syndrome. Although the factors linking insulin resistance to these syndromes are not precisely defined yet, evidence suggests that the elevated plasma free fatty acid (FFA level plays an important role in the development of skeletal muscle insulin resistance. Accordantly, in vivo and in vitro exposure of skeletal muscle and myocytes to physiological concentrations of saturated fatty acids is associated with insulin resistance condition. Several mechanisms have been postulated to account for fatty acids-induced muscle insulin resistance, including Randle cycle, oxidative stress, inflammation and mitochondrial dysfunction. Here we reviewed experimental evidence supporting the involvement of each of these propositions in the development of skeletal muscle insulin resistance induced by saturated fatty acids and propose an integrative model placing mitochondrial dysfunction as an important and common factor to the other mechanisms.

  12. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid

    OpenAIRE

    Giannattasio, Sergio; Guaragnella, Nicoletta; ?dralevi?, Ma?a; Marra, Ersilia

    2013-01-01

    Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the mol...

  13. Probing the mechanical properties, conformational changes, and interactions of nucleic acids with magnetic tweezers.

    Science.gov (United States)

    Kriegel, Franziska; Ermann, Niklas; Lipfert, Jan

    2017-01-01

    Nucleic acids are central to the storage and transmission of genetic information. Mechanical properties, along with their sequence, both enable and fundamentally constrain the biological functions of DNA and RNA. For small deformations from the equilibrium conformations, nucleic acids are well described by an isotropic elastic rod model. However, external forces and torsional strains can induce conformational changes, giving rise to a complex force-torque phase diagram. This review focuses on magnetic tweezers as a powerful tool to precisely determine both the elastic parameters and conformational transitions of nucleic acids under external forces and torques at the single-molecule level. We review several variations of magnetic tweezers, in particular conventional magnetic tweezers, freely orbiting magnetic tweezers and magnetic torque tweezers, and discuss their characteristic capabilities. We then describe the elastic rod model for DNA and RNA and discuss conformational changes induced by mechanical stress. The focus lies on the responses to torque and twist, which are crucial in the mechanics and interactions of nucleic acids and can directly be measured using magnetic tweezers. We conclude by highlighting several recent studies of nucleic acid-protein and nucleic acid-small-molecule interactions as further applications of magnetic tweezers and give an outlook of some exciting developments to come. Copyright © 2016. Published by Elsevier Inc.

  14. Flotation performances and adsorption mechanism of α-hydroxyoctyl phosphinic acid to cassiterite

    Science.gov (United States)

    Li, Fangxu; Zhong, Hong; Zhao, Gang; Wang, Shuai; Liu, Guangyi

    2015-10-01

    In this paper, the flotation performances and adsorption mechanism of α-hydroxyoctyl phosphinic acid (HPA) to cassiterite were investigated by adsorption experiments, micro-flotation tests, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The micro-flotation results indicated that compared with styrene phosphonic acid (SPA), diphosphonic acid (DPA), benzohydroxamic acid (BHA) and salicylhydroxamic acid (SHA), HPA exhibited excellent collecting power to cassiterite and superior selectivity against magnetite or hematite over a wide pH range. The results of adsorption experiments and zeta potential deduced that HPA chemisorb on cassiterite surfaces. The results of FTIR inferred HPA chemisorb onto cassiterite surfaces through its P and O atoms with the P-H and O-H bonds broken. XPS analysis further demonstrated HPA react with Sn species by formation of Sn-O-P and Sn-P bond.

  15. Adsorption mechanisms for fatty acids on DLC and steel studied by AFM and tribological experiments

    International Nuclear Information System (INIS)

    Simič, R.; Kalin, M.

    2013-01-01

    Fatty acids are known to affect the friction and wear of steel contacts via adsorption onto the surface, which is one of the fundamental boundary-lubrication mechanisms. The understanding of the lubrication mechanisms of polar molecules on diamond-like carbon (DLC) is, however, still insufficient. In this work we aimed to find out whether such molecules have a similar effect on DLC coatings as they do on steel. The adsorption of hexadecanoic acid in various concentrations (2–20 mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage of the adsorbed fatty-acid molecules was analysed. In addition, tribological tests were performed to correlate the wear and friction behaviours in tribological contacts with the adsorption of molecules on the surface under static conditions. A good correlation between the AFM results and the tribological behaviour was observed. We confirmed that fatty acids can adsorb onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for DLC coatings. The adsorption of the fatty acid onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction. Tentative adsorption mechanisms that include an environmental species effect, a temperature effect and a tribochemical effect are proposed for DLC and steel surfaces based on our results and few potential mechanisms found in literature.

  16. Adsorption mechanisms for fatty acids on DLC and steel studied by AFM and tribological experiments

    Energy Technology Data Exchange (ETDEWEB)

    Simič, R.; Kalin, M., E-mail: mitjan.kalin@tint.fs.uni-lj.si

    2013-10-15

    Fatty acids are known to affect the friction and wear of steel contacts via adsorption onto the surface, which is one of the fundamental boundary-lubrication mechanisms. The understanding of the lubrication mechanisms of polar molecules on diamond-like carbon (DLC) is, however, still insufficient. In this work we aimed to find out whether such molecules have a similar effect on DLC coatings as they do on steel. The adsorption of hexadecanoic acid in various concentrations (2–20 mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage of the adsorbed fatty-acid molecules was analysed. In addition, tribological tests were performed to correlate the wear and friction behaviours in tribological contacts with the adsorption of molecules on the surface under static conditions. A good correlation between the AFM results and the tribological behaviour was observed. We confirmed that fatty acids can adsorb onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for DLC coatings. The adsorption of the fatty acid onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction. Tentative adsorption mechanisms that include an environmental species effect, a temperature effect and a tribochemical effect are proposed for DLC and steel surfaces based on our results and few potential mechanisms found in literature.

  17. [Effects of isocitrate lyase from Mycobacterium tuberculosis on the survival of Mycobacterium smegmatis in macrophage and mechanism thereof].

    Science.gov (United States)

    Li, Jun-Ming; Wan, La-Gen; Zhu, Dao-Yin; Li, Na; He, Yong-Lin; Yang, Chun

    2008-02-26

    To investigate the effects of isocitrate lyase (ICL) from Mycobacterium tuberculosis (MTB-icl) on the survival of Mycobacterium smegmatis (MS) in macrophage and illuminate the possible mechanisms. MTB-icl gene was amplified by PCR and cloned into Ecoli-Mycobacterium shuttle plasmid pUV15 to obtain recombinant shuttle plasmid pUV15-icl expressing ICL-GFP. The recombinant shuttle plasmid pUV15-icl and blank plasmid pUV15 were induced into MS of the line 1-2c so as to obtain rMS-pUV15-icl and rMS-pUV15. Shuttle plasmid rMS-pUV15-IG expressing ICL-green fluorescent protein (GFP) was constructed. rMS-pUV15-IG and MS 1-2c were used to infect the murine macrophages of the line RAW264.7, fluorescence microscopy was used to observe the expression of ICL-GFP. The expression of ICL in the MS swallowed by the macrophages was verified by RT-PCR and Western blotting. Another macrophages RAW264.7 were cultured and infected with rMS-pUV15-icl and rMS-pUV15 respectively. 0, 24, and 48 hours later macrophages were collected and the number of MS colonies was calculated. The interferon (IFN)-gamma and nitrogen oxide (NO) concentrations in the culture supernatants of macrophages infected by rMS-pUV15-icl and rMS-pUV15 were measured by ELISA and Griess assay respectively. The apoptotic rate of the macrophages was assayed by in situ TUNEL technique. Western blotting showed that the MTB ICL protein expression of the rMS-pUV15-icl was significantly higher than that of rMS-pUVI5. Fluorescence microscopy showed green fluorescence in the RAW264.7 cells infected with rMS-pUV15-IG, but not ion the RAW264.7 cells infected with MS 1-2c. 0 h after the infection of the macrophages there was not significant difference in the MS amount in the macrophages between the rMS-pUV15-isl and rMS-pUV15 groups, and 24 h and 48 h later the MS amounts of the rMS-pUV15-icl group were (32.78 +/- 2.90) x 10(3) and (23.33 + 2.34) x 10(3) respectively, both significantly higher than those of the rMS-pUV15 group [(14

  18. Mechanism of catalytic action of oxide systems in reactions of aldehyde oxidation to carboxylic acids

    International Nuclear Information System (INIS)

    Andrushkevich, T.V.

    1997-01-01

    Mechanism of selective action of oxide catalysts (on the base of V 2 O 4 , MoO 3 ) of aldehyde oxidation to acids is considered, reaction acrolein oxidation to acrylic acid is taken as an example. Multistage mechanism of the process is established; it involves consequent transformation of coordination-bonded aldehyde into carbonyl-bonded aldehyde and symmetric carboxylate. Principles of active surface construction are formulated, they take into account the activity of stabilization center of concrete intermediate compound and bond energy of oxygen with surface. (author)

  19. Glucose-lowering effects and mechanisms of the bile acid-sequestering resin sevelamer

    DEFF Research Database (Denmark)

    Brønden, Andreas; Mikkelsen, Kristian; Sonne, David P

    2018-01-01

    and mechanism(s) of sevelamer in patients with type 2 diabetes. MATERIALS AND METHODS: In this double-blinded randomized controlled trial, we randomized 30 patients with type 2 diabetes to sevelamer (n=20) or placebo (n=10). Participants were subjected to standardized 4-hour liquid meal tests at baseline...... synthesis of bile acids, a shift towards a more hydrophilic bile acid pool and increased lipogenesis. No glucagon-like peptide-1-mediated effects on insulin, glucagon or gastric emptying were evident, which point to limited contribution of this incretin hormone to the glucose-lowering effect of sevelamer...

  20. Surviving the crisis: Adaptive wisdom, coping mechanisms and local responses to avian influenza threats in Haining, China.

    Science.gov (United States)

    Zhang, Letian; Pan, Tianshu

    2008-04-01

    Based on ethnographic research conducted in the summer of 2006, this paper examines local responses to the imminent threat of avian flu in Haining County of Zhejiang Province. During our field investigation, we conducted interviews with officials from local medical institutions (including the hospitals, the animal husbandry and veterinary station, and health clinics), to bureaus of public health and agro-economy. We also visited chicken farms, restaurants and farming households. We address the following factors that commonly structured the perceptions and actions of different social actors in the area of study: The changing mode of information-sharing and communication practices in the local communities; the official drive to professionalize the emergency response management system in the county; and the coping mechanisms that helped the villagers and town residents to weather the storm of avian flu. Our field research suggests that collective survival consciousness was translated into a spirit of voluntarism during the crisis. One important practical lesson we have learned from this study is that the adaptive wisdom embedded in local memories demonstrated its operational worth as a resourceful knowledge base for ordinary farmers to deal with food shortage, famine, plague and future pandemics.

  1. Kinetics and mechanism of the oxidation of uranium (IV) by hypochlorous acid in aqueous acidic perchlorate media

    International Nuclear Information System (INIS)

    Silverman, R.A.; Gordon, G.

    1976-01-01

    The oxidation of uranium(IV) by hypochlorous acid has been studied in aqueous sodium perchlorate--perchloric acid solutions. The reaction U 4 + + 2HOCl = UO 2 2 + + Cl 2 (aq) + 2H + proceeds appropriate to the rate law --d[U(IV)]/dt = k 0 . [U 4+ ][HOCl][H + ] -1 . At 25 0 and 3 M ionic strength, k 0 is 1.08 +- 0.07 sec -1 . Over the 1--25 0 temperature range, ΔH 2+ is 18.4 +- 0.1 kcal mole -1 , and ΔS 2+ is 3.1 +- 0.4 eu. The inverse hydrogen ion dependence of the rate law is explained by a rapid preequilibrium, in which a proton is lost from one of the reactants. A uranyl-like activated complex, [H 2 UO 2 Cl 3+ ] 2+ , is suggested, with one proton likely to be residing on each oxygen atom. Evidence is presented that the mechanism involves a two-electron transfer, with the intermediate chloride ion rapidly reacting with hypochlorous acid to form chlorine. The uranium(IV)-hypochlorous acid reaction plays an important role in the oxidation of uranium(IV) by aqueous chlorine solutions. The magnitude of this role was seriously underestimated by previous investigators

  2. Amino Acids Regulate mTORC1 by an Obligate Two-step Mechanism*

    Science.gov (United States)

    Dyachok, Julia; Earnest, Svetlana; Iturraran, Erica N.; Cobb, Melanie H.

    2016-01-01

    The mechanistic target of rapamycin complex 1 (mTORC1) coordinates cell growth with its nutritional, hormonal, energy, and stress status. Amino acids are critical regulators of mTORC1 that permit other inputs to mTORC1 activity. However, the roles of individual amino acids and their interactions in mTORC1 activation are not well understood. Here we demonstrate that activation of mTORC1 by amino acids includes two discrete and separable steps: priming and activation. Sensitizing mTORC1 activation by priming amino acids is a prerequisite for subsequent stimulation of mTORC1 by activating amino acids. Priming is achieved by a group of amino acids that includes l-asparagine, l-glutamine, l-threonine, l-arginine, l-glycine, l-proline, l-serine, l-alanine, and l-glutamic acid. The group of activating amino acids is dominated by l-leucine but also includes l-methionine, l-isoleucine, and l-valine. l-Cysteine predominantly inhibits priming but not the activating step. Priming and activating steps differ in their requirements for amino acid concentration and duration of treatment. Priming and activating amino acids use mechanisms that are distinct both from each other and from growth factor signaling. Neither step requires intact tuberous sclerosis complex of proteins to activate mTORC1. Concerted action of priming and activating amino acids is required to localize mTORC1 to lysosomes and achieve its activation. PMID:27587390

  3. Antimicrobial Activity of Ferulic Acid Against Cronobacter sakazakii and Possible Mechanism of Action.

    Science.gov (United States)

    Shi, Chao; Zhang, Xiaorong; Sun, Yi; Yang, Miaochun; Song, Kaikuo; Zheng, Zhiwei; Chen, Yifei; Liu, Xin; Jia, Zhenyu; Dong, Rui; Cui, Lu; Xia, Xiaodong

    2016-04-01

    Cronobacter sakazakii is an opportunistic pathogen transmitted by food that affects mainly newborns, infants, and immune-compromised adults. In this study, the antibacterial activity of ferulic acid was tested against C. sakazakii strains. Minimum inhibitory concentration of ferulic acid against C. sakazakii strains was determined using the agar dilution method. Changes in intracellular pH, membrane potential and intracellular ATP concentration were measured to elucidate the possible antibacterial mechanism. Moreover, SYTO 9 nucleic acid staining was used to assess the effect of ferulic acid on bacterial membrane integrity. Cell morphology changes were observed under a field emission scanning electron microscope. The minimum inhibitory concentrations of ferulic acid against C. sakazakii strains ranged from 2.5 to 5.0 mg/mL. Addition of ferulic acid exerted an immediate and sustained inhibition of C. sakazakii proliferation. Ferulic acid affected the membrane integrity of C. sakazakii, as evidenced by intracellular ATP concentration decrease. Moreover, reduction of intracellular pH and cell membrane hyperpolarization were detected in C. sakazakii after exposure to ferulic acid. Reduction of green fluorescence indicated the injury of cell membrane. Electronic microscopy confirmed that cell membrane of C. sakazakii was damaged by ferulic acid. Our results demonstrate that ferulic acid has moderate antimicrobial activity against C. sakazakii. It exerts its antimicrobial action partly through causing cell membrane dysfunction and changes in cellular morphology. Considering its antimicrobial properties, together with its well-known nutritional functions, ferulic acid has potential to be developed as a supplement in infant formula or other foods to control C. sakazakii.

  4. Insights into the mechanism of acetic acid hydrogenation to ethanol on Cu(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Minhua; Yao, Rui; Jiang, Haoxi; Li, Guiming [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Chen, Yifei, E-mail: yfchen@tju.edu.cn [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)

    2017-08-01

    Highlights: • The scission of C–OH bond of acetic acid is the rate-determined step in acetic acid hydrogenation to ethanol on Cu(111). • Acetic acid adsorption and reaction barrier of C–OH scission of acetic acid are factors related to acetic acid conversion. • Acetaldehyde adsorption and reaction barriers of O–H formation of C{sub 2}–oxygenates are factors related to ethanol selectivity. - Abstract: Density functional theory (DFT) calculations were employed to theoretically explain the reaction mechanism of acetic acid hydrogenation to ethanol on Cu catalyst. The activation barriers of key elementary steps and the adsorption configurations of key intermediates involved in acetic acid hydrogenation on Cu(111) surface were investigated. The results indicated that the direct dissociation of acetic acid to acetyl (CH{sub 3}COOH → CH{sub 3}CO + OH) is the rate-determined step. The activation barrier of acetic acid scission to acetyl and the adsorption energy of acetic acid are two descriptors which could determine the conversion of acetic acid. The descriptors might have effects on the ethanol selectivity including: the adsorption energy of acetaldehyde and the activation barriers for O−H bond formation of C{sub 2}-oxygenates (CH{sub 3}CO + H → CH{sub 3}COH, CH{sub 3}CHO + H → CH{sub 3}CHOH and CH{sub 3}CH{sub 2}O + H → CH{sub 3}CH{sub 2}OH). These proposed descriptors could be used as references to design new Cu-based catalysts that have excellent catalytic performance.

  5. Identification of lactic acid bacteria in the feces of dairy cows fed whole crop maize silage to assess the survival of silage bacteria in the gut.

    Science.gov (United States)

    Han, Hongyan; Wang, Chao; Li, Yanbing; Yu, Zhu; Xu, Qingfang; Li, Guangpeng; Minh, Tang Thuy; Nishino, Naoki

    2018-01-01

    In order to assess the survival of lactic acid bacteria (LAB) in whole crop maize silage in the gut of dairy cows, one representative silage sample and three different feces samples were collected from dairy cows on three dairy farms in Hua Bei, China and three dairy farms in Kyushu, Japan. The composition of the bacterial community was examined by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction. Lactobacillus acetotolerans was detected in all bunker-made maize silage samples, regardless of the dairy farm or sampling region from which they were sourced. A total of eight LAB species were detected in the maize silage samples, of which three (L. acetotolerans, L. pontis and L. casei) appeared to survive digestion. The populations of L. acetotolerans in silage and feces were 10 6-7 and 10 3-4 copies/g, respectively, indicating that, even for the LAB species showing potential survival in the gut, competition in this niche may be harsh and the population may substantially decrease during the digestion process. It may be difficult for silage LAB to survive in the gut of silage-fed dairy cows, because marked decrease in population can take place during the digestion process, even for surviving species. © 2017 Japanese Society of Animal Science.

  6. Survival of buffalo bull spermatozoa: effect on structure and function due to alpha-lipoic acid and cholesterol-loaded cyclodextrin.

    Science.gov (United States)

    Fayyaz, M H; Ahmad, M; Ahmad, N

    2017-05-01

    Sperm survival depending upon integral membranes and function is imperative for fertilization. This study was designed to augment survival of buffalo spermatozoa using alpha-lipoic acid (ALA) and cholesterol-loaded cyclodextrin (CLC) during cryopreservation. Semen was frozen using 0, 0.5, 1, 1.5, 2 and 2.5 mmol L -1 ALA (experiment 1) and ALA or CLC separately or together (experiment 2). Semen was assessed for post-thaw motility, plasma membrane integrity (PMI), intact acrosome and plasma membrane (IACR-IPM) and DNA integrity at 0, 1.5, 3 and 4.5 hr of incubation. In experiment 1, use of 0.5 mmol L -1 ALA enhanced the sperm cryosurvival and post-thaw longevity than other groups up to 4.5 hr of incubation, and this concentration of ALA was used in second experiment with CLC. The results revealed higher (p sperm survival function and time of sperm attributes due to use of ALA than CLC and control. However, the sperm quality did not improve (p > .05) when ALA was combined with CLC. In conclusion, survival of buffalo bull spermatozoa during freeze-thawing and post-thaw incubation can be enhanced more with ALA than CLC or control, followed by CLC than control. However, there is no synergistic effect on survival of buffalo bull spermatozoa due to ALA and CLC. © 2016 Blackwell Verlag GmbH.

  7. Biologically Safe Poly(l-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties.

    Science.gov (United States)

    Oyama, Hideko T; Tanishima, Daisuke; Ogawa, Ryohei

    2017-04-10

    Although poly(l-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.

  8. Ursolic acid inhibits the initiation, progression of prostate cancer and prolongs the survival of TRAMP mice by modulating pro-inflammatory pathways.

    Directory of Open Access Journals (Sweden)

    Muthu K Shanmugam

    Full Text Available Prostate cancer is one of the leading causes of cancer death among men worldwide. In this study, using transgenic adenocarcinoma of mouse prostate (TRAMP mice, the effect of diet enriched with 1% w/w ursolic acid (UA was investigated to evaluate the stage specific chemopreventive activity against prostate cancer. We found that TRAMP mice fed with UA diet for 8 weeks (weeks 4 to 12 delayed formation of prostate intraepithelial neoplasia (PIN. Similarly, mice fed with UA diet for 6 weeks (weeks 12 to 18 inhibited progression of PIN to adenocarcinoma as determined by hematoxylin and eosin staining. Finally, TRAMP mice fed with UA diet for 12 weeks (weeks 24 to 36 demonstrated markedly reduced tumor growth without any significant effects on total body weight and prolonged overall survival. With respect to the molecular mechanism, we found that UA down-regulated activation of various pro-inflammatory mediators including, NF-κB, STAT3, AKT and IKKα/β phosphorylation in the dorsolateral prostate (DLP tissues that correlated with the reduction in serum levels of TNF-α and IL-6. In addition, UA significantly down-regulated the expression levels of cyclin D1 and COX-2 but up-regulated the levels of caspase-3 as revealed by immunohistochemical analysis of tumor tissue sections. Finally, UA was detected in serum samples obtained from various mice groups fed with enriched diet in nanogram quantity indicating that it is well absorbed in the GI tract. Overall, our findings provide strong evidence that UA can be an excellent agent for both the prevention and treatment of prostate cancer.

  9. Mechanical dyssynchrony evaluated by tissue Doppler cross-correlation analysis is associated with long-term survival in patients after cardiac resynchronization therapy

    DEFF Research Database (Denmark)

    Risum, Niels; Williams, Eric S; Khouri, Michel G

    2013-01-01

    Aims Pre-implant assessment of longitudinal mechanical dyssynchrony using cross-correlation analysis (XCA) was tested for association with long-term survival and compared with other tissue Doppler imaging (TDI)-derived indices. Methods and results In 131 patients referred for cardiac resynchroniz...

  10. Cinnamic Acid and Its Derivatives: Mechanisms for Prevention and Management of Diabetes and Its Complications

    Directory of Open Access Journals (Sweden)

    Sirichai Adisakwattana

    2017-02-01

    Full Text Available With recent insight into the development of dietary supplements and functional foods, search of effective phytochemical compounds and their mechanisms involved in prevention and management of diabetes and its complications are now being assessed. Cinnamic acid and its derivatives occur naturally in high levels of plant-based foods. Among various biological activities, cinnamic acid and its derivatives are associated with a beneficial influence on diabetes and its complications. The aim of the review is to summarize the potential mechanisms of these compounds for prevention and management of diabetes and its complications. Based on several in vitro studies and animal models, cinnamic acid and its derivatives act on different mechanism of actions, including stimulation of insulin secretion, improvement of pancreatic β-cell functionality, inhibition of hepatic gluconeogenesis, enhanced glucose uptake, increased insulin signaling pathway, delay of carbohydrate digestion and glucose absorption, and inhibition of protein glycation and insulin fibrillation. However, due to the limited intestinal absorption being a result of low bioavailability of cinnamic acid and its derivatives, current improvement efforts with entrapping into solid and liquid particles are highlighted. Further human clinical studies are needed to clarify the effects of cinnamic acid and its derivatives in diabetic patients.

  11. TolC is important for bacterial survival and oxidative stress response in Salmonella enterica serovar Choleraesuis in an acidic environment.

    Science.gov (United States)

    Lee, Jen-Jie; Wu, Ying-Chen; Kuo, Chih-Jung; Hsuan, Shih-Ling; Chen, Ter-Hsin

    2016-09-25

    The outer membrane protein TolC, which is one of the key components of several multidrug efflux pumps, is thought to be involved in various independent systems in Enterobacteriaceae. Since the acidic environment of the stomach is an important protection barrier against foodborne pathogen infections in hosts, we evaluated whether TolC played a role in the acid tolerance of Salmonella enterica serovar Choleraesuis. Comparison of the acid tolerance of the tolC mutant and the parental wild-type strain showed that the absence of TolC limits the ability of Salmonella to sustain life under extreme acidic conditions. Additionally, the mutant exhibited morphological changes during growth in an acidic medium, leading to the conflicting results of cell viability measured by spectrophotometry and colony-forming unit counting. Reverse-transcriptional-PCR analysis indicated that acid-related molecules, apparatus, or enzymes and oxidation-induced factors were significantly affected by the acidic environment in the null-tolC mutant. The elongated cellular morphology was restored by adding antioxidants to the culture medium. Furthermore, we found that increased cellular antioxidative activity provides an overlapping protection against acid killing, demonstrating the complexity of the bacterial acid stress response. Our findings reinforce the multifunctional characteristics of TolC in acid tolerance or oxidative stress resistance and support the correlative protection mechanism between oxygen- and acid-mediated stress responses in Salmonella enterica serovar Choleraesuis. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Acetalization of 2-Hydroxybenzaldehyde mechanism using halogen acid catalysts based on ab initio methods

    Science.gov (United States)

    Yusuf, Muhammad; Roza, Destria; Nasution, Ahmad Kamil

    2017-11-01

    The computational calculation was performed on the acetalization of 2-hydroxybenzaldehyde by using ab initio method. Ab initio method is derived directly from theoretical principles with no inclusion of experimental data and this is an approximate quantum mechanical calculation. The aim of this research was to studies the acetalization of 2-hydroxybenzaldehyde mechanism using halogen acid catalysts. Computational calculation which was applied on the acetalization of 2-hydroxybenzaldehyde using halogen acid catalysts provided possible reaction steps. The first step was formation of a labile hemiacetal because it is essentially tetrahedral intermediates containing a leaving group. The second step was formation of a stable acetal. The results of computational calculation of acetalization of 2-hydroxybenzaldehyde provided possible energy change in the each step of the reaction process. A labile hemiacetal showed higher energy (481.04 kJ/mol) than 2-hydroxybenzaldehyde dimethyl acetal (65.32 kJ/mol) and 2-hydroxybenzaldehyde (0 kJ/mol) due to its instability. In general, acetalization of 2-hydroxybenzaldehyde reaction is a reversible reaction. The effect of Lewis acidity on halogen acid catalysts was also studied in this research. Based on the Mulliken charge on the H atom, it is found that HF has the highest Lewis acidity compared to other halogen acids with order HF> HCl> HBr> HI. As a result, HF was the efficient catalysts for acetalization of 2-Hydroxybenzaldehyde.

  13. [Regulating acid stress resistance of lactic acid bacteria--a review].

    Science.gov (United States)

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-07-04

    As cell factories, lactic acid bacteria are widely used in food, agriculture, pharmaceutical and other industries. Acid stress is one the important survival challenges encountered by lactic acid bacteria both in fermentation process and in the gastrointestinal tract. Recently, the development of systems biology and metabolic engineering brings unprecedented opportunity for further elucidating the acid tolerance mechanisms and improving the acid stress resistance of lactic acid bacteria. This review addresses physiological mechanisms of lactic acid bacteria during acid stress. Moreover, strategies to improve the acid stress resistance of lactic acid were proposed.

  14. Poly(para-dioxanone) and poly(l-lactic acid) blends : Thermal, mechanical, and morphological properties

    NARCIS (Netherlands)

    Pezzin, A.P.T.; Alberda van Ekenstein, G.O.R.; Zavaglia, C.A.C.; ten Brinke, G.; Deuk, E.A.R.

    2003-01-01

    Blends of two semicrystalline polymers, poly(L-lactic acid) (PLLA) and poly-p-dioxanone (PPD) have been prepared by solvent casting in different compositions. Thermal, morphological, and mechanical properties of the blends were studied using modulated differential scanning calorimetry, wide-angle

  15. Kinetics and mechanism of the oxidation of formic and oxalic acids ...

    Indian Academy of Sciences (India)

    Kinetics and mechanism of oxidation of formic and oxalic acids by quinolinium fluorochromate (QFC) have been studied in dimethylsulphoxide. The main product of oxidation is carbon dioxide. The reaction is first-order with respect to QFC. Michaelis-Menten type of kinetics were observed with respect to the reductants.

  16. Physical and mechanical properties of extruded poly(lactic acid)-based Paulownia elongata biocomposites

    Science.gov (United States)

    Paulownia wood flour (PWF), a byproduct of milling lumber, was tested as bio-filler with polylactic acid (PLA). Paulownia wood (PW) shavings were milled and separated into particle fractions and then blended with PLA with a single screw extruder. Mechanical and thermal properties were tested. Dif...

  17. Kinetics and mechanism of the oxidation of formic and oxalic acids ...

    Indian Academy of Sciences (India)

    Abstract. Kinetics and mechanism of oxidation of formic and oxalic acids by quinolinium fluorochromate (QFC) have been studied in dimethylsulphoxide. The main product of oxidation is carbon dioxide. The reaction is first-order with respect to. QFC. Michaelis–Menten type of kinetics were observed with respect to the ...

  18. Mechanism of alkylation of isobutane by olefins in the presence of sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Baiburskii, V.L.; Khadzhiev, S.N.; Ovsyannikov, V.P.

    1992-05-10

    The authors attempted here to examine the mechanism of alkylation of isobutane by olefins in the presence of sulfuric acid in terms of an initial stage of activation of isoparaffin. The version of formation of tert-alkyl cations and the role of the catalyst in this stage were analyzed. 10 refs., 1 fig., 1 tab.

  19. Theoretical Structures of Triflic Acid-Water Clusters and the Molecular Mechanism of Proton Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Paddison, S.J.; Pratt, L.R.; Zawodzinski, T.A.

    1998-11-01

    Structural and energetic information required for recently proposed quasi-chemical theories of solution chemistry have been obtained for clusters of water with triflic acid, CF{sub 3}SO{sub 3}H(H{sub 2}O){sub n} for n=1-6. Quantum mechanical calculations on the clusters indicate that the acid proton does not dissociate with n=1 or 2 hydrating water molecules, but does dissociate for n>=3 water molecule partners. The computed minimum energy structures indicate that both ''Eigen'' (H{sub 9}O{sub 4}{sup +}) (n=3,4,6) and ''Zundel'' (H{sub 5}O{sub 2}{sup +}) (n=5) structures are likely to play a role in the molecular mechanism of acid dissociation in Nafion{reg_sign}.

  20. Mechanisms Underlying the Anti-Aging and Anti-Tumor Effects of Lithocholic Bile Acid

    Directory of Open Access Journals (Sweden)

    Anthony Arlia-Ciommo

    2014-09-01

    Full Text Available Bile acids are cholesterol-derived bioactive lipids that play essential roles in the maintenance of a heathy lifespan. These amphipathic molecules with detergent-like properties display numerous beneficial effects on various longevity- and healthspan-promoting processes in evolutionarily distant organisms. Recent studies revealed that lithocholic bile acid not only causes a considerable lifespan extension in yeast, but also exhibits a substantial cytotoxic effect in cultured cancer cells derived from different tissues and organisms. The molecular and cellular mechanisms underlying the robust anti-aging and anti-tumor effects of lithocholic acid have emerged. This review summarizes the current knowledge of these mechanisms, outlines the most important unanswered questions and suggests directions for future research.

  1. Mechanism of Asp24 Upregulation in Brucella abortus Rough Mutant with a Disrupted O-Antigen Export System and Effect of Asp24 in Bacterial Intracellular Survival

    Science.gov (United States)

    Tian, Mingxing; Qu, Jing; Han, Xiangan; Ding, Chan; Wang, Shaohui; Peng, Daxin

    2014-01-01

    We previously showed that Brucella abortus rough mutant strain 2308 ΔATP (called the ΔrfbE mutant in this study) exhibits reduced intracellular survival in RAW264.7 cells and attenuated persistence in BALB/c mice. In this study, we performed microarray analysis to detect genes with differential expression between the ΔrfbE mutant and wild-type strain S2308. Interestingly, acid shock protein 24 gene (asp24) expression was significantly upregulated in the ΔrfbE mutant compared to S2308, as confirmed by quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. Further studies using additional strains indicated that the upregulation of asp24 occurred only in rough mutants with disrupted O-antigen export system components, including the ATP-binding protein gene rfbE (bab1_0542) and the permease gene rfbD (bab1_0543), while the ΔwboA rough mutant (which lacks an O-antigen synthesis-related glycosyltransferase) and the RB51 strain (a vaccine strain with the rough phenotype) showed no significant changes in asp24 expression compared to S2308. In addition, abolishing the intracellular O-antigen synthesis of the ΔrfbE mutant by deleting the wboA gene (thereby creating the ΔrfbE ΔwboA double-knockout strain) recovered asp24 expression. These results indicated that asp24 upregulation is associated with intracellular O-antigen synthesis and accumulation but not with the bacterial rough phenotype. Further studies indicated that asp24 upregulation in the ΔrfbE mutant was associated neither with bacterial adherence and invasion nor with cellular necrosis on RAW264.7 macrophages. However, proper expression of the asp24 gene favors intracellular survival of Brucella in RAW264.7 cells and HeLa cells during an infection. This study reveals a novel mechanism for asp24 upregulation in B. abortus mutants. PMID:24752516

  2. Autotoxicity mechanism of Oryza sativa: transcriptome response in rice roots exposed to ferulic acid

    Science.gov (United States)

    2013-01-01

    Background Autotoxicity plays an important role in regulating crop yield and quality. To help characterize the autotoxicity mechanism of rice, we performed a large-scale, transcriptomic analysis of the rice root response to ferulic acid, an autotoxin from rice straw. Results Root growth rate was decreased and reactive oxygen species, calcium content and lipoxygenase activity were increased with increasing ferulic acid concentration in roots. Transcriptome analysis revealed more transcripts responsive to short ferulic-acid exposure (1- and 3-h treatments, 1,204 genes) than long exposure (24 h, 176 genes). Induced genes were involved in cell wall formation, chemical detoxification, secondary metabolism, signal transduction, and abiotic stress response. Genes associated with signaling and biosynthesis for ethylene and jasmonic acid were upregulated with ferulic acid. Ferulic acid upregulated ATP-binding cassette and amino acid/auxin permease transporters as well as genes encoding signaling components such as leucine-rich repeat VIII and receptor-like cytoplasmic kinases VII protein kinases, APETALA2/ethylene response factor, WRKY, MYB and Zinc-finger protein expressed in inflorescence meristem transcription factors. Conclusions The results of a transcriptome analysis suggest the molecular mechanisms of plants in response to FA, including toxicity, detoxicification and signaling machinery. FA may have a significant effect on inhibiting rice root elongation through modulating ET and JA hormone homeostasis. FA-induced gene expression of AAAP transporters may contribute to detoxicification of the autotoxin. Moreover, the WRKY and Myb TFs and LRR-VIII and SD-2b kinases might regulate downstream genes under FA stress but not general allelochemical stress. This comprehensive description of gene expression information could greatly facilitate our understanding of the mechanisms of autotoxicity in plants. PMID:23705659

  3. Mechanisms involved in the selective transfer of long chain polyunsaturted fatty acids to the fetus

    Directory of Open Access Journals (Sweden)

    Alfonso eGil-Sánchez

    2011-09-01

    Full Text Available The concentration of long chain polyunsaturated fatty acid (LCPUFA in the fetal brain increases dramatically from the third trimester until 18 months of life. Several studies have shown an association between the percentage of maternal plasma docosahexaenoic acid (DHA during gestation and development of the cognitive functions in the neonate. Since only very low levels of LCPUFA are synthesized in the fetus and placenta, their primary source for the fetus is that of maternal origin. Both in vitro and human in vivo studies using labelled fatty acids have shown the preferential transfer of LCPUFA from the placenta to the fetus compared with other fatty acids, although the mechanisms involved are still uncertain. The placenta takes up circulating maternal non-esterified fatty acids (NEFA and fatty acids released mainly by maternal lipoprotein lipase and endothelial lipase. These NEFA may enter the cell by passive diffusion or by means of membrane carrier proteins. Once in the cytosol, NEFA bind to cytosolic fatty acid-binding proteins for transfer to the fetal circulation or can be oxidized within the trophoblasts and even re-esterified and stored in lipid droplets (LD. Although trophoblast cells are not specialized in lipid storage, LCPUFA may up-regulate peroxisome proliferator activated receptor-γ (PPARγ and hence the gene expression of fatty acid transport carriers, fatty acid acyl-CoA synthetases and adipophilin or other enzymes related with lipolysis, modifying their rate of placental transfer and metabolization. The placental transfer of LCPUFA during pregnancy seems to be a key factor in the neurological development of the fetus. Increased knowledge on the factors that modify placental transfer of fatty acids would contribute to our understanding of this complex process.

  4. Short communication: Latin-style fresh cheese enhances lactic acid bacteria survival but not Listeria monocytogenes resistance under in vitro simulated gastrointestinal conditions.

    Science.gov (United States)

    Silva, C C G; Domingos-Lopes, M F P; Magalhães, V A F; Freitas, D A S R; Coelho, M C; Rosa, H J D; Dapkevicius, M L N E

    2015-07-01

    Different studies in humans have provided evidence about the health benefits of probiotics. However, most probiotic strains do not maintain good viability in the harsh conditions of the gastrointestinal tract (GIT). In the present study, Latin-style fresh cheese produced with potential probiotic bacteria was tested to evaluate this cheese type as a food carrier for the delivery of viable microorganisms after exposure to simulated GIT conditions. The resistance of 28 lactic acid bacteria (LAB) strains and Listeria monocytogenes upon exposure to acidic conditions (pH 2.5) and bile and pancreatic enzymes (0.3% of bile salts and 0.1% of pancreatin) was evaluated in vitro. When compared with fresh cultures, fresh cheese greatly improved LAB survival to simulated GIT conditions, as no loss of viability was observed in either acidic conditions (pH 2.5) or bile salts and pancreatin environment over a 3-h period. In opposition, L. monocytogenes did not survive after 1h under acidic conditions. These data demonstrated that Latin-style fresh cheese could play an important role in probiotic protection against gastrointestinal juices, enhancing delivery within the gut and thereby maximizing potential health benefits of LAB. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  5. Effect of ionizing radiation dose, temperature, and atmosphere on the survival of Salmonella typhimurium in sterile, mechanically deboned chicken meat.

    Science.gov (United States)

    Thayer, D W; Boyd, G

    1991-02-01

    The response to gamma radiation (0 to 3.60 kGy; 100 krad = 1 kGy) of Salmonella typhimurium was tested in otherwise sterile, mechanically deboned chicken meat (MDCM) in the absence of competing microflora. Response was determined at temperatures of -20 to +20 C and when the MDCM was packaged in vacuum or in the presence of air. A central composite response-surface design was used to test the response of the pathogen to the treatments in a single experiment. Predictive equations were developed from the analyses of variances of the resulting data. The accuracy of each predictive equation was tested by further studies of the effects of gamma radiation on S. typhimurium in the presence or absence of air at -20, 0, and +20 C. All data were then analyzed to refine the predictive equations further. Both the original and the refined equations adequately predicted the response of S. typhimurium in MDCM to gamma radiation doses up to 3.60 kGy in the presence of air or in vacuo. Gamma irradiation was significantly more lethal for S. typhimurium in the presence of air and at higher temperatures. The final equations predict a reduction in the number of surviving Salmonella in MDCM irradiated to 1.50 kGy at -20 C of 2.53 logs in air or 2.12 logs if irradiated in vacuum. If the contaminated MDCM were to receive a dose of 3.0 kGy at -20 C in air, the number of Salmonella would be decreased by 4.78 logs, and if irradiated in vacuum, by 4.29 logs.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Effect of ionizing radiation dose, temperature, and atmosphere on the survival of Salmonella typhimurium in sterile, mechanically deboned chicken meat

    International Nuclear Information System (INIS)

    Thayer, D.W.; Boyd, G.

    1991-01-01

    The response to gamma radiation (0 to 3.60 kGy; 100 krad = 1 kGy) of Salmonella typhimurium was tested in otherwise sterile, mechanically deboned chicken meat (MDCM) in the absence of competing microflora. Response was determined at temperatures of -20 to +20 C and when the MDCM was packaged in vacuum or in the presence of air. A central composite response-surface design was used to test the response of the pathogen to the treatments in a single experiment. Predictive equations were developed from the analyses of variances of the resulting data. The accuracy of each predictive equation was tested by further studies of the effects of gamma radiation on S. typhimurium in the presence or absence of air at -20, 0, and +20 C. All data were then analyzed to refine the predictive equations further. Both the original and the refined equations adequately predicted the response of S. typhimurium in MDCM to gamma radiation doses up to 3.60 kGy in the presence of air or in vacuo. Gamma irradiation was significantly more lethal for S. typhimurium in the presence of air and at higher temperatures. The final equations predict a reduction in the number of surviving Salmonella in MDCM irradiated to 1.50 kGy at -20 C of 2.53 logs in air or 2.12 logs if irradiated in vacuum. If the contaminated MDCM were to receive a dose of 3.0 kGy at -20 C in air, the number of Salmonella would be decreased by 4.78 logs, and if irradiated in vacuum, by 4.29 logs

  7. Selective survival rescue in 15-lipoxygenase-1-deficient retinal pigment epithelial cells by the novel docosahexaenoic acid-derived mediator, neuroprotectin D1.

    Science.gov (United States)

    Calandria, Jorgelina M; Marcheselli, Victor L; Mukherjee, Pranab K; Uddin, Jasim; Winkler, Jeremy W; Petasis, Nicos A; Bazan, Nicolas G

    2009-06-26

    The integrity of the retinal pigment epithelial (RPE) cell is essential for the survival of rod and cone photoreceptor cells. Several stressors, including reactive oxygen species, trigger apoptotic damage in RPE cells preceded by an anti-inflammatory, pro-survival response, the formation of neuroprotectin D1 (NPD1), an oxygenation product derived from the essential omega-3 fatty acid family member docosahexaenoic acid. To define the ability of NPD1 and other endogenous novel lipid mediators in cell survival, we generated a stable knockdown human RPE (ARPE-19) cell line using short hairpin RNA to target 15-lipoxygenase-1. The 15-lipoxygenase-1-deficient cells exhibited 30% of the protein expression, and 15-lipoxygenase-2 remained unchanged, as compared with an ARPE-19 cell line control established using nonspecific short hairpin RNA transfected cells. NPD1 synthesis was stimulated by tumor necrosis factor alpha/H2O2-mediated oxidative stress in nonspecific cells (controls), whereas in silenced cells, negligible amounts of NPD1, 12(S)- and 15(S)-hydroxyeicosatetraenoic acid, and lipoxin A4 were found under these conditions. Neither control nor the deficient cells showed an increase in 15-lipoxygenase-1 protein content after 16 h of oxidative stress, suggesting that the increased activity of 15-lipoxygenase-1 is due to activation of pre-existing proteins. 15-Lipoxygenase-silenced cells also displayed an exacerbated sensitivity to oxidative stress-induced apoptosis when compared with the control cells. NPD1 selectively and potently rescued 15-lipoxygenase-silenced cells from oxidative stress-induced apoptosis. These results demonstrate that 15-lipoxygenase-1 is activated by oxidative stress in ARPE-19 cells and that NPD1 is part of an early survival signaling in RPE cells.

  8. Selective Survival Rescue in 15-Lipoxygenase-1-deficient Retinal Pigment Epithelial Cells by the Novel Docosahexaenoic Acid-derived Mediator, Neuroprotectin D1*

    Science.gov (United States)

    Calandria, Jorgelina M.; Marcheselli, Victor L.; Mukherjee, Pranab K.; Uddin, Jasim; Winkler, Jeremy W.; Petasis, Nicos A.; Bazan, Nicolas G.

    2009-01-01

    The integrity of the retinal pigment epithelial (RPE) cell is essential for the survival of rod and cone photoreceptor cells. Several stressors, including reactive oxygen species, trigger apoptotic damage in RPE cells preceded by an anti-inflammatory, pro-survival response, the formation of neuroprotectin D1 (NPD1), an oxygenation product derived from the essential omega-3 fatty acid family member docosahexaenoic acid. To define the ability of NPD1 and other endogenous novel lipid mediators in cell survival, we generated a stable knockdown human RPE (ARPE-19) cell line using short hairpin RNA to target 15-lipoxygenase-1. The 15-lipoxygenase-1-deficient cells exhibited 30% of the protein expression, and 15-lipoxygenase-2 remained unchanged, as compared with an ARPE-19 cell line control established using nonspecific short hairpin RNA transfected cells. NPD1 synthesis was stimulated by tumor necrosis factor α/H2O2-mediated oxidative stress in nonspecific cells (controls), whereas in silenced cells, negligible amounts of NPD1, 12(S)- and 15(S)-hydroxyeicosatetraenoic acid, and lipoxin A4 were found under these conditions. Neither control nor the deficient cells showed an increase in 15-lipoxygenase-1 protein content after 16 h of oxidative stress, suggesting that the increased activity of 15-lipoxygenase-1 is due to activation of pre-existing proteins. 15-Lipoxygenase-silenced cells also displayed an exacerbated sensitivity to oxidative stress-induced apoptosis when compared with the control cells. NPD1 selectively and potently rescued 15-lipoxygenase-silenced cells from oxidative stress-induced apoptosis. These results demonstrate that 15-lipoxygenase-1 is activated by oxidative stress in ARPE-19 cells and that NPD1 is part of an early survival signaling in RPE cells. PMID:19403949

  9. Cloud droplet activation mechanisms of amino acid aerosol particles: insight from molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Xin Li

    2013-07-01

    Full Text Available Atmospheric amino acids constitute a large fraction of water-soluble organic nitrogen compounds in aerosol particles, and have been confirmed as effective cloud condensation nuclei (CCN materials in laboratory experiments. We present a molecular dynamics (MD study of six amino acids with different structures and chemical properties that are relevant to the remote marine atmospheric aerosol–cloud system, with the aim of investigating the detailed mechanism of their induced changes in surface activity and surface tension, which are important properties for cloud drop activation. Distributions and orientations of the amino acid molecules are studied; these l-amino acids are serine (SER, glycine (GLY, alanine (ALA, valine (VAL, methionine (MET and phenylalanine (PHE and are categorised as hydrophilic and amphiphilic according to their affinities to water. The results suggest that the presence of surface-concentrated amphiphilic amino acid molecules give rise to enhanced Lennard–Jones repulsion, which in turn results in decreased surface tension of a planar interface and an increased surface tension of the spherical interface of droplets with diameters below 10 nm. The observed surface tension perturbation for the different amino acids under study not only serves as benchmark for future studies of more complex systems, but also shows that amphiphilic amino acids are surface active. The MD simulations used in this study reproduce experimental results of surface tension measurements for planar interfaces and the method is therefore applicable for spherical interfaces of nano-size for which experimental measurements are not possible to conduct.

  10. Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

    Science.gov (United States)

    Suto, Kaori; Urabe, Ken; Naruse, Kouji; Uchida, Kentaro; Matsuura, Terumasa; Mikuni-Takagaki, Yuko; Suto, Mitsutoshi; Nemoto, Noriko; Kamiya, Kentaro; Itoman, Moritoshi

    2012-03-01

    Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

  11. Survival of lactic acid bacteria from fermented milks in an in vitro digestion model exploiting sequential incubation in human gastric and duodenum juice.

    Science.gov (United States)

    Faye, T; Tamburello, A; Vegarud, G E; Skeie, S

    2012-02-01

    In the present study, the survival of 9 lactic acid bacteria (5 Lactococcus strains, 3 Lactobacillus strains, and 1 strain of Enterococcus hirae), was investigated in vitro under conditions similar to human digestion using human gastric and duodenal juices. The tolerance of the bacteria was also tested with traditional methods using acidic conditions and bile salts. The strains were subjected to a model digestive system comprising sequential incubation in human gastric and duodenal juices, in a 2-step digestion assay at 37°C, simulating the human upper gastrointestinal tract with human gastric juices at pH 2.5 and human duodenal juices at pH 7. The bacterial strains were tested either as washed cells from culture media or in fermented milk. The initial in vitro testing in acid and bile salts showed that Lactobacillus strains and the E. hirae strain displayed a significantly higher acid tolerance than the lactococci. The lactobacilli and the Enterococcus numbers increased, whereas the lactococci decreased at least 1 log during the bile salt treatment. The Lactobacillus strains showed the highest survival rate in the model digestive system when washed bacterial cultures were used with a minor log reduction, whereas the lactococci numbers were reduced by at least log 4. However, when using fermented milks in the model digestion system it was demonstrated that the Enterococcus strain and 2 strains of Lactococcus lactis ssp. cremoris benefited significantly from the presence of the fermented milk as food matrix, with log numbers >log 7 and 5, respectively, after digestion of the fermented milk. The analyses reported comprise a comprehensive in vitro testing regimen suitable for evaluation of the survival of candidate probiotic bacteria in human digestion as an initial prescreen to clinical trials. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. The impact of mechanical ventilation time before initiation of extracorporeal life support on survival in pediatric respiratory failure: a review of the Extracorporeal Life Support Registry.

    Science.gov (United States)

    Domico, Michele B; Ridout, Deborah A; Bronicki, Ronald; Anas, Nick G; Cleary, John Patrick; Cappon, James; Goldman, Allan P; Brown, Katherine L

    2012-01-01

    To evaluate the relationship between duration of mechanical ventilation before the initiation of extracorporeal life support and the survival rate in children with respiratory failure. Extracorporeal life support has been used as a rescue therapy for >30 yrs in children with severe respiratory failure. Previous studies suggest patients who received >7-10 days of mechanical ventilation were not acceptable extracorporeal life support candidates as a result of irreversible lung damage. A retrospective review encompassing the past 10 yrs of the International Extracorporeal Life Support Organization Registry (January 1, 1999, to December 31, 2008). Extracorporeal Life Support Organization Registry database. A total of 1325 children (≥ 30 days and ≤ 18 yrs) met inclusion criteria. None. The following pre-extracorporeal life support variables were identified as independently and significantly related to the chance of survival: 1) >14 days of ventilation vs. 0-7 days was adverse (odds ratio, 0.32; p 7-10 or >10-14 days of pre-extracorporeal life support ventilation did not have a statistically significant decrease in survival as compared with patients who received 0-7 days. There was a clear relationship between the number of mechanical ventilation days before the initiation of extracorporeal life support and survival. However; there was no statistically significant decrease in survival until >14 days of pre-extracorporeal life support ventilation was reached regardless of underlying diagnosis. We found no evidence to suggest that prolonged mechanical ventilation should be considered as a contraindication to extracorporeal life support in children with respiratory failure before 14 days.

  13. Mechanism of Body Weight Reducing Effect of Oral Boric Acid Intake

    Directory of Open Access Journals (Sweden)

    Erhan Aysan

    2013-01-01

    Full Text Available Objective. The effect of oral boric acid intake on reducing body weight has been previously demonstrated although the mechanism has been unclear. This research study reveals the mechanism. Subjects. Twelve mice were used, in groups of six each in the control and study groups. For five days, control group mice drank standard tap water while during the same time period the study group mice drank tap water which contains 0.28 mg/250 mL boric acid. After a 5-day period, gene expression levels for uncoupling proteins (UCPs in the white adipose tissue (WAT, brown adipose tissue (BAT, and skeletal muscle tissue (SMT and total body weight changes were analyzed. Results. Real time PCR analysis revealed no significant change in UCP3 expressions, but UCP2 in WAT (: 0.0317, BAT (: 0.014, and SMT (: 0.0159 and UCP1 in BAT (: 0.026 were overexpressed in the boric acid group. In addition, mice in the boric acid group lost body weight (mean 28.1% while mice in the control group experienced no weight loss but a slight weight gain (mean 0.09%, . Conclusion. Oral boric acid intake causes overexpression of thermogenic proteins in the adipose and skeletal muscle tissues. Increasing thermogenesis through UCP protein pathway results in the accelerated lipolysis and body weight loss.

  14. Mechanical, thermal and morphological properties of glutaraldehyde crosslinked bovine pericardium followed by glutamic acid treatment

    Directory of Open Access Journals (Sweden)

    Gilberto Goissis

    2009-03-01

    Full Text Available Major problems with valve bioprostheses are associated with progressive structural deterioration and calcification, directly associated with the use of glutaraldehyde (GA. This work describes the effects of GA processing and borate/glutamic acid buffer treatment on the mechanical, thermal and morphological properties of 0.5% GA crosslinked bovine pericardium (BP. The results showed that while the treatment of 0.5% GA crosslinked BP with borate/glutamic acid significantly improves the mechanical properties, it had no visible effect on surface morphology. Better surface preservation was only achieved for BP pre-treated with a lower GA concentration followed by the conventional treatment (0.5% GA. Improvements in mechanical properties probably arises from structural changes probably involving the depolymerization of polymeric GA crosslinks and an increase electrostatic interaction due to covalent binding of glutamic acid to free carbonyl groups (Schiff base.The results indicate that the treatment GA crosslinked BP with borate/glutamic acid buffer may be an attractive procedure for the manufacture of heart valve bioprostheses.

  15. Better Rooting Procedure to Enhance Survival Rate of Field Grown Malaysian Eksotika Papaya Transformed with 1-Aminocyclopropane-1-Carboxylic Acid Oxidase Gene

    Science.gov (United States)

    Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom

    2013-01-01

    A high survival rate for transformed papaya plants when transferred to the field is useful in the quest for improving the commercial quality traits. We report in this paper an improved rooting method for the production of transformed Malaysian Eksotika papaya with high survival rate when transferred to the field. Shoots were regenerated from embryogenic calli transformed with antisense and RNAi constructs of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes using the Agrobacterium tumefaciens-mediated transformation method. Regenerated transformed shoots, each measuring approximately 3-4 cm in height, were cultured in liquid half-strength Murashige and Skoog (MS) medium or sterile distilled water, and with either perlite or vermiculite supplementation. All the culturing processes were conducted either under sterile or nonsterile condition. The results showed that rooting under sterile condition was better. Shoots cultured in half-strength MS medium supplemented with vermiculite exhibited a 92.5% rooting efficiency while perlite showed 77.5%. The survival rate of the vermiculite-grown transformed papaya plantlets after transfer into soil, contained in polybags, was 94%, and the rate after transfer into the ground was 92%. Morpho-histological analyses revealed that the tap roots were more compact, which might have contributed to the high survival rates of the plantlets. PMID:25969786

  16. Better rooting procedure to enhance survival rate of field grown malaysian eksotika papaya transformed with 1-aminocyclopropane-1-carboxylic Acid oxidase gene.

    Science.gov (United States)

    Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom

    2013-01-01

    A high survival rate for transformed papaya plants when transferred to the field is useful in the quest for improving the commercial quality traits. We report in this paper an improved rooting method for the production of transformed Malaysian Eksotika papaya with high survival rate when transferred to the field. Shoots were regenerated from embryogenic calli transformed with antisense and RNAi constructs of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes using the Agrobacterium tumefaciens-mediated transformation method. Regenerated transformed shoots, each measuring approximately 3-4 cm in height, were cultured in liquid half-strength Murashige and Skoog (MS) medium or sterile distilled water, and with either perlite or vermiculite supplementation. All the culturing processes were conducted either under sterile or nonsterile condition. The results showed that rooting under sterile condition was better. Shoots cultured in half-strength MS medium supplemented with vermiculite exhibited a 92.5% rooting efficiency while perlite showed 77.5%. The survival rate of the vermiculite-grown transformed papaya plantlets after transfer into soil, contained in polybags, was 94%, and the rate after transfer into the ground was 92%. Morpho-histological analyses revealed that the tap roots were more compact, which might have contributed to the high survival rates of the plantlets.

  17. Antinociceptive Properties of Ascorbic Acid: Evidence for the Mechanism of Action

    Directory of Open Access Journals (Sweden)

    Zeraati

    2014-09-01

    Full Text Available Background Ascorbic acid is amongst important water-soluble vitamins and when used orally in high-doses it has been observed to relieve pain and reduce opioid use in patients. However no controlled trial has compared the antinociceptive effects of ascorbic acid with other analgesic groups on animal models, and investigated the involved mechanisms. Objectives In the present study, the antinociceptive effect of vitamin C on male mice was investigated and compared with morphine and diclofenac. Also, possible mechanisms were assayed. Materials and Methods Male albino mice were used in this study. Antinociception was measured using the writhing test, tail flick and formalin tests. Ascorbic acid was used in three doses (30, 150 and 300 mg/kg, IP and compared with the antinociceptive effects of 10 mg/kg of morphine as an opioid analgesic agent and 5-10 mg/kg of diclofenac as a nonsteroidal anti-inflammatory drug (NSAID analgesic agent.The antinociceptive effect of ascorbic acid (300 mg/kg was compared before and after treatment with naloxone (4 mg/kg, ondansetron (0.5 mg/kg, atropine (5 mg/kg and metoclopramide (1 mg/kg in the writhing test. Results Vitamin C caused dose-dependent antinociceptive effects in acetic acid writhing test (P < 0.05. It had no significant effect in the tail flick test. Meanwhile, vitamin C in high doses reduced pain in the second phase of the formalin test (P < 0.05. Morphine had higher nociceptive effects in comparison to ascorbic acid in the writhing test (P < 0.05. In the second phase of the formalin test the antinociceptive effects of vitamin C (300 mg/kg was not significantly different with morphine at dose of 10 mg/kg. There was not significant difference between vitamin C (300 mg/kg and diclofenac (10 mg/kg in the second phase of the formalin test. Metoclopramide and ondansetrone reduced the antinociceptive effects of vitamin C. Conclusions The results obtained from the acetic acid induced writhing test and second

  18. Insights into the mechanism of acetic acid hydrogenation to ethanol on Cu(111) surface

    Science.gov (United States)

    Zhang, Minhua; Yao, Rui; Jiang, Haoxi; Li, Guiming; Chen, Yifei

    2017-08-01

    Density functional theory (DFT) calculations were employed to theoretically explain the reaction mechanism of acetic acid hydrogenation to ethanol on Cu catalyst. The activation barriers of key elementary steps and the adsorption configurations of key intermediates involved in acetic acid hydrogenation on Cu(111) surface were investigated. The results indicated that the direct dissociation of acetic acid to acetyl (CH3COOH → CH3CO + OH) is the rate-determined step. The activation barrier of acetic acid scission to acetyl and the adsorption energy of acetic acid are two descriptors which could determine the conversion of acetic acid. The descriptors might have effects on the ethanol selectivity including: the adsorption energy of acetaldehyde and the activation barriers for Osbnd H bond formation of C2-oxygenates (CH3CO + H → CH3COH, CH3CHO + H → CH3CHOH and CH3CH2O + H → CH3CH2OH). These proposed descriptors could be used as references to design new Cu-based catalysts that have excellent catalytic performance.

  19. [Effect of ferulic acid on cholesterol efflux in macrophage foam cell formation and potential mechanism].

    Science.gov (United States)

    Chen, Fu-xin; Wang, Lian-kai

    2015-02-01

    The formation of macrophage-derived foam cells is a typical feature of atherosclerosis (AS). Reverse cholesterol efflux (RCT) is one of important factors for the formation of macrophage foam cells. In this study, macrophage form cells were induced by oxidized low density lipoprotein (ox-LDL) and then treated with different concentrations of ferulic acid, so as to observe the effect of ferulic acid on the intracellular lipid metabolism in the ox-LDL-induced macrophage foam cell formation, the cholesterol efflux and the mRNA expression and protein levels of ATP binding cassette transporter A1 (ABCA1) and ATP binding cassette transporter G1 (ABCG1) that mediate cholesterol efflux, and discuss the potential mechanism of ferulic acid in resisting AS. According to the findings, compared with the control group, the ox-LDL-treated group showed significant increase in intracellular lipid content, especially for the cholesterol content; whereas the intracellular lipid accumulation markedly decreased, after the treatment with ferulic acid. The data also demonstrated that the mRNA and protein expressions of ABCA1 and ABCG1 significantly increased after macrophage foam cells were treated with different concentrations of ferulic acid. In summary, ferulic acid may show the anti-atherosclerosis effect by increasing the surface ABCA1 and ABCG1 expressions of macrophage form cells and promoting cholesterol efflux.

  20. Effects of submergence on growth and survival of saplings of three wetland trees differing in adaptive mechanisms for flood tolerance

    Directory of Open Access Journals (Sweden)

    Fumiko Iwanaga

    2015-04-01

    Full Text Available Aim of study: Withstanding total submergence and reaeration following submergence is essential for the survival and establishment of wetland species. We focused on “LOES–low oxygen escape syndrome” and “LOQS–low oxygen quiescence syndrome” and compared tolerances to total submergence among wetland woody species differing in morphological adaptation to soil flooding. Area of study, materials and methods: This study examined the survival of 2-year-old saplings of Taxodium distichum and Metasequioia glyptostroboides (LOQS species, and Alnus japonica (LOES species, during and after total submergence. Saplings were completely submerged, then de-submerged to determine trends in survival and growth Main results: The M. glyptostroboides and A. japonica saplings could not survive prolonged submergence for more than 8 weeks, whereas saplings of T. distichum survived for over 2 years. Submerged saplings of all species showed no significant growth or modifications in morphology and anatomy under water, such as shoot elongation, adventitious root formation, and/or aerenchyma development. All T. distichum saplings that were de-submerged in the second year had the same pattern of shoot growth regardless of differences in timing and seasonality of de-submergence. Wood formation in T. distichum saplings ceased during submergence and resumed after de-submergence in spring and summer, but not in autumn. Research highlights: T. distichum saplings, which survived longer submergence periods than A. japonica and M. glyptostroboides, had physiological characteristics, such as suspension of growth and metabolism, which allowed survival of protracted total submergence (at least 2 years when saplings were immersed during the dormant stage before leaf flushing.

  1. Mechanism of Corrosion by Naphthenic Acids and Organosulfur Compounds at High Temperatures

    Science.gov (United States)

    Jin, Peng

    Due to the law of supply and demand, the last decade has witnessed a skyrocketing in the price of light sweet crude oil. Therefore, refineries are increasingly interested in "opportunity crudes", characterized by their discounted price and relative ease of procurement. However, the attractive economics of opportunity crudes come with the disadvantage of high acid/organosulfur compound content, which could lead to corrosion and even failure of facilities in refineries. However, it is generally accepted that organosulfur compounds may form protective iron sulfide layers on the metal surface and decrease the corrosion rate. Therefore, it is necessary to investigate the corrosive property of crudes at high temperatures, the mechanism of corrosion by acids (naphthenic acids) in the presence of organosulfur compounds, and methods to mitigate its corrosive effect. In 2004, an industrial project was initiated at the Institute for Corrosion and Multiphase Technology to investigate the corrosion by naphthenic acids and organosulfur compounds. In this project, for each experiment there were two experimentation phases: pretreatment and challenge. In the first pretreatment phase, a stirred autoclave was filled with a real crude oil fraction or model oil of different acidity and organosulfur compound concentration. Then, the stirred autoclave was heated to high temperatures to examine the corrosivity of the oil to different materials (specimens made from CS and 5% Cr containing steel were used). During the pretreatment, corrosion product layers were formed on the metal surface. In the second challenge phase, the steel specimens pretreated in the first phase were inserted into a rotating cylinder autoclave, called High Velocity Rig (HVR). The HVR was fed with a high-temperature oil solution of naphthenic acids to attack the iron sulfide layers. Based on the difference of specimen weight loss between the two steps, the net corrosion rate could be calculated and the protectiveness

  2. Fatty Acid Uptake and Lipid Storage Induced by HIF-1α Contribute to Cell Growth and Survival after Hypoxia-Reoxygenation

    Directory of Open Access Journals (Sweden)

    Karim Bensaad

    2014-10-01

    Full Text Available Summary: An in vivo model of antiangiogenic therapy allowed us to identify genes upregulated by bevacizumab treatment, including Fatty Acid Binding Protein 3 (FABP3 and FABP7, both of which are involved in fatty acid uptake. In vitro, both were induced by hypoxia in a hypoxia-inducible factor-1α (HIF-1α-dependent manner. There was a significant lipid droplet (LD accumulation in hypoxia that was time and O2 concentration dependent. Knockdown of endogenous expression of FABP3, FABP7, or Adipophilin (an essential LD structural component significantly impaired LD formation under hypoxia. We showed that LD accumulation is due to FABP3/7-dependent fatty acid uptake while de novo fatty acid synthesis is repressed in hypoxia. We also showed that ATP production occurs via β-oxidation or glycogen degradation in a cell-type-dependent manner in hypoxia-reoxygenation. Finally, inhibition of lipid storage reduced protection against reactive oxygen species toxicity, decreased the survival of cells subjected to hypoxia-reoxygenation in vitro, and strongly impaired tumorigenesis in vivo. : Bensaad et al. now show that FABP3 and FABP7 are induced by HIF-1α and lead to a significant lipid droplet (LD accumulation in hypoxia. In hypoxia-reoxygenation, ATP production occurs via fatty acid β-oxidation or glycogen degradation in a cell-type-dependent manner, while inhibition of LD formation increases ROS toxicity and decreases cell survival in vitro and strongly impairs tumorigenesis in vivo.

  3. Omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid and their mechanisms of action on apolipoprotein B-containing lipoproteins in humans: a review.

    Science.gov (United States)

    Oscarsson, Jan; Hurt-Camejo, Eva

    2017-08-10

    Epidemiological and genetic studies suggest that elevated triglyceride (TG)-rich lipoprotein levels in the circulation increase the risk of cardiovascular disease. Prescription formulations of omega-3 fatty acids (OM3FAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduce plasma TG levels and are approved for the treatment of patients with severe hypertriglyceridemia. Many preclinical studies have investigated the TG-lowering mechanisms of action of OM3FAs, but less is known from clinical studies. We conducted a review, using systematic methodology, of studies in humans assessing the mechanisms of action of EPA and DHA on apolipoprotein B-containing lipoproteins, including TG-rich lipoproteins and low-density lipoproteins (LDLs). A systematic search of PubMed retrieved 55 articles, of which 30 were used in the review; 35 additional arrticles were also included. In humans, dietary DHA is retroconverted to EPA, while production of DHA from EPA is not observed. Dietary DHA is preferentially esterified into TGs, while EPA is more evenly esterified into TGs, cholesterol esters and phospholipids. The preferential esterification of DHA into TGs likely explains the higher turnover of DHA than EPA in plasma. The main effects of both EPA and DHA are decreased fasting and postprandial serum TG levels, through reduction of hepatic very-low-density lipoprotein (VLDL)-TG production. The exact mechanism for reduced VLDL production is not clear but does not include retention of lipids in the liver; rather, increased hepatic fatty acid oxidation is likely. The postprandial reduction in TG levels is caused by increased lipoprotein lipase activity and reduced serum VLDL-TG concentrations, resulting in enhanced chylomicron clearance. Overall, no clear differences between the effects of EPA and DHA on TG levels, or on turnover of TG-rich lipoproteins, have been observed. Effects on LDL are complex and may be influenced by genetics, such as APOE genotype. EPA and

  4. Effect of dietary (n-3 highly unsaturated fatty acids on growth and survival of fat snook (Centropomus parallelus, Pisces: Centropomidae larvae during first feeding

    Directory of Open Access Journals (Sweden)

    M.E.B. Seiffert

    2001-05-01

    Full Text Available The effect of rotifers, Brachionus rotundiformis (S-type, fed three different diets: A (rotifer fed Nannochloropsis oculata, B (rotifer fed N. oculata and baker's yeast, 1:1, and C (rotifer fed N. oculata and baker's yeast, 1:1, and enriched with Selcoâ, was evaluated based on the survival, growth and swim bladder inflation rate of fat snook larvae. Rotifers of treatment A had higher levels (4.58 mg/g dry weight of eicosapentaenoic acid (EPA than B (1.81 mg/g dry weight, and similar levels (0.04 and 0.06 mg/g dry weight, respectively of docosahexaenoic acid (DHA. Rotifers of treatment C had the highest levels of EPA (13.2 mg/g dry weight and DHA (6.08 mg/g dry weight. Fat snook eggs were obtained by spawning induction with human chorionic gonadotropin. Thirty hours after hatching, 30 larvae/liter were stocked in black cylindric-conical tanks (36-liter capacity. After 14 days of culture, there were no significant differences among treatments. Mean standard length was 3.13 mm for treatment A, 3.17 mm for B, and 3.39 mm for C. Mean survival rates were very low (2.7% for treatment A, 2.3% for B, and 1.8% for C. Swim bladder inflation rates were 34.7% for treatment A, 27.1% for B, and 11.9% for C. The lack of differences in growth and survival among treatments showed that the improvement of the dietary value of rotifer may not have been sufficient to solve the problem of larval rearing. Some other factor, probably pertaining to the quality of the larvae, may have negatively influenced survival.

  5. Novel molecular mechanisms of antitumor action of dichloroacetate against T cell lymphoma: Implication of altered glucose metabolism, pH homeostasis and cell survival regulation.

    Science.gov (United States)

    Kumar, Ajay; Kant, Shiva; Singh, Sukh Mahendra

    2012-07-30

    Pyruvate dehydrogenase kinase (PDK) inhibits pyruvate dehydrogenase (PDH) activity and thus promotes energetic switch from mitochondrial glucose oxidation to cytoplasmic glycolysis in cancerous cells (a phenomenon known as the 'Warburg effect') for their energy need, which facilitates the cancer progression by resisting induction of apoptosis and promoting tumor metastasis. Thus, in the present investigation, we explored the molecular mechanisms of the tumoricidal action of dichloroacetate (DCA), a pyruvate dehydrogenase kinase inhibitor, on cells of a murine T cell lymphoma, designated as Dalton's lymphoma (DL). In vitro treatment of tumor cells with DCA inhibited their survival accompanied by a modulation of the biophysical composition of tumor-conditioned medium with respect to pH, glucose and lactate. DCA treatment also altered expression of HIF1-α and pH regulators: VATPase and MCT1 and production of cytokines: IL-10, IL-6 and IFN-γ. Moreover, we also observed an alteration in the expression of other apoptosis and cell survival regulatory molecules: PUMA, GLUT1, Bcl2, p53, CAD, caspase-3 and HSP70. The study discusses the role of novel molecular mechanisms underlying DCA-dependent inhibition of tumor cell survival. This study shows for the first time that DCA-dependent alteration of tumor cell survival involves altered pH homeostasis and glucose metabolism. Thus, these findings will provide a new insight for therapeutic applications of DCA as a novel antineoplastic agent against T cell lymphoma. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Kinetics and Mechanism of Oxidation of Aromatic Aldehydes by Imidazolium Dichromate in Aqueous Acetic Acid Medium

    Directory of Open Access Journals (Sweden)

    S. Sheik Mansoor

    2009-01-01

    Full Text Available The kinetics of oxidation of benzaldehyde (BA and para-substituted benzaldehydes by imidazolium dichromate (IDC has been studied in aqueous acetic acid medium in the presence of perchloric acid. The reaction is first order each in [IDC], [Substrate] and [H+]. The reaction rates have been determined at different temperatures and the activation parameters calculated. Electron withdrawing substituents are found to increase the reaction and electron releasing substituents are found to retard the rate of the reaction and the rate data obey the Hammett relationship. The products of the oxidation are the corresponding acids. The rate decreases with the increase in the water content of the medium. A suitable mechanism is proposed.

  7. Fresh-cut lettuce in modified atmosphere packages stored at improper temperatures supports enterohemorrhagic E. coli isolates to survive gastric acid challenge.

    Science.gov (United States)

    Chua, D; Goh, K; Saftner, R A; Bhagwat, A A

    2008-04-01

    Incidences of foodborne outbreaks involving enterohemorrhagic Escherichia coli strains with mutations in a key regulatory gene, rpoS, have been reported. Incentives, if any, for losing this regulatory function are not clear since the RpoS regulator is required for the expression of several environmental stress tolerance genes. RpoS also positively regulates 2 of the 3 acid-resistance systems of E. coli under aerobic growth conditions and enables the pathogen to survive gastric acid challenge. We selected 7 enterohemorrhagic E. coli isolates, 6 of which are known to carry defective rpoS gene, and then analyzed resistance to synthetic gastric juice after the strains were inoculated on fresh-cut lettuce and stored under modified atmosphere packaging (MAP) conditions. Subatmospheric oxygen partial pressures in MAP enabled all 6 rpoS-defective isolates to induce acid resistance over the 8-d storage period if the temperature was >or= 15 degrees C. No acid resistance was induced for MAP-stored lettuce left at temperatures lettuce packed and stored under aerobic conditions. The data underscore the impending danger of abusive storage temperatures especially with regard to the application of MAP to extend the shelf life of fresh produce. The results also highlight the biological significance of having multiple acid-resistance pathways and the complex regulatory network of enterohemorrhagic E. coli strains.

  8. Study on the Effects of Adipic Acid on Properties of Dicyandiamide-Cured Electrically Conductive Adhesive and the Interaction Mechanism

    Science.gov (United States)

    Wang, Ling; Wan, Chao; Fu, Yonggao; Chen, Hongtao; Liu, Xiaojian; Li, Mingyu

    2014-01-01

    A small quantity of adipic acid was found to improve the performance of dicyandiamide-cured electrically conductive adhesive (ECA) by enhancing its electrical conductivity and mechanical properties. The mechanism of action of the adipic acid and its effects on the ECA were examined. The results indicated that adipic acid replaced the electrically insulating lubricant on the surface of the silver flakes, which significantly improved the electrical conductivity. Specifically, one of the acidic functional groups in adipic acid reacted with the silver flakes, and an amidation reaction occurred between the other acidic functional group in adipic acid and the dicyandiamide, which participated in the curing reaction. Therefore, adipic acid may act as a coupling agent to improve the overall ECA performance.

  9. Tunneling corrosion mechanism of the hot forged austenitic stainless steel in highly oxidizing nitric acid

    International Nuclear Information System (INIS)

    Nagano, Hiroo; Kajimura, Haruhiko

    1993-01-01

    Austenitic Stainless Steels have been used for reprocessing plants where spent nuclear fuels are dealt with in hot nitric acid. Conventional stainless steels are resistant enough to nitric acid. However, they are prone to localized corrosion when nitric acid becomes highly oxidizing with birth of oxidants such as Ce 4+ or Cr 6+ ion during the reprocessing. Pitting type corrosion, so-called tunneling or end-grain corrosion occurred on the forgings of 25%-20%-Nb stainless steel (310Nb stainless steel) in such nitric acid solutions because of transpassive corrosion. It has been well known that metal surfaces of steel products casted, forged or rolled are susceptible to the tunneling corrosion in aggressive corrosion media. Nevertheless, neither clear explanations of the mechanism nor definite countermeasures have been proposed yet. This paper describes the mechanism and countermeasures on the tunneling corrosion of stainless steels in nitric acid relevant to spent nuclear fuel reprocessing. The results obtained are as follows: both general and intergranular corrosion occur on austenitic stainless steels in boiling 8N HNO 3 with Cr 6+ ions. Tunneling corrosion is initiated and propagates at the metal surfaces of 310Nb stainless steel forgings along chromium depleted areas vertical to metal flows. The grooves due to the tunneling corrosion are of diameters of 0.5 to 2 mm with a maximum depth of 6mm depending on exposure time and Cr 6+ concentration in nitric acid. Tunneling corrosion proceeds by build up of galvanic corrosion cells with Cr depleted parts as anodes and their neighborhoods as cathodes. The Cr depleted parts are formed during solidification of ingots and still retained parallel to the metal flow even after forging. The ESR (Electro Slag Remelting) is one of the useful preventive methods to tunneling corrosion from the view point of steel homogenization

  10. Lactic acid/wood-based composite material. Part 2: Physical and mechanical performance.

    Science.gov (United States)

    Noël, Marion; Mougel, Eric; Fredon, Emmanuel; Masson, Daniel; Masson, Eric

    2009-10-01

    The synthesis of an innovative bio-composite material based on wood and lactic acid oligomers has been reported in Part 1. As a continuation of this previous work, this paper examines the bio-composite material's physical and mechanical performance. Properties were assessed in terms of dimensional stability, decay resistance, leaching, bending, shearing, compression and hardness testing. It has been shown that physical performance of the bio-composite was highly improved, in spite of high leaching mass loss. The mechanical structural properties were not strongly affected, except in decrease of shearing resistance due to the middle lamella degradation. An increase in hardness properties was also noticed.

  11. Identifying the receptor subtype selectivity of retinoid X and retinoic acid receptors via quantum mechanics.

    Science.gov (United States)

    Tsuji, Motonori; Shudo, Koichi; Kagechika, Hiroyuki

    2017-03-01

    Understanding and identifying the receptor subtype selectivity of a ligand is an important issue in the field of drug discovery. Using a combination of classical molecular mechanics and quantum mechanical calculations, this report assesses the receptor subtype selectivity for the human retinoid X receptor (hRXR) and retinoic acid receptor (hRAR) ligand-binding domains (LBDs) complexed with retinoid ligands. The calculated energies show good correlation with the experimentally reported binding affinities. The technique proposed here is a promising method as it reveals the origin of the receptor subtype selectivity of selective ligands.

  12. Stearic acid based oleogels: a study on the molecular, thermal and mechanical properties.

    Science.gov (United States)

    Sagiri, S S; Singh, Vinay K; Pal, K; Banerjee, I; Basak, Piyali

    2015-03-01

    Stearic acid and its derivatives have been used as gelators in food and pharmaceutical gel formulations. However, the mechanism pertaining to the stearic acid based gelation has not been deciphered yet. Keeping that in mind, we investigated the role of stearic acid on physic-chemical properties of oleogel. For this purpose, two different oil (sesame oil and soy bean oil) formulations/oleogels were prepared. In depth analysis of gel kinetics, gel microstructure, molecular interactions, thermal and mechanical behaviors of the oleogels were done. The properties of the oleogels were dependent on the type of the vegetable oil used and the concentration of the stearic acid. Avrami analysis of DSC thermograms indicated that heterogeneous nucleation was coupled with the one-dimensional growth of gelator fibers as the key phenomenon in the formation of oleogels. Viscoelastic and pseudoplastic nature of the oleogels was analyzed in-depth by fitting the stress relaxation data in modified Peleg's model and rheological studies, respectively. Textural studies have revealed that the coexistence of hydrogen bond dissipation and formation of new bonds is possible under stress conditions in the physical oleogels. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Activation mechanism of melB tyrosinase from Aspergillus oryzae by acidic treatment.

    Science.gov (United States)

    Fujieda, Nobutaka; Murata, Michiaki; Yabuta, Shintaro; Ikeda, Takuya; Shimokawa, Chizu; Nakamura, Yukihiro; Hata, Yoji; Itoh, Shinobu

    2013-01-01

    The pro form of recombinant tyrosinase from Aspergillus oryzae (melB) shows no catalytic activity, but acid treatment (around pH 3.5) of protyrosinase activates it to induce tyrosinase activity. Circular dichroism spectra, gel filtration analysis, and colorimetric assay have indicated that acid treatment around pH 3.5 induced the disruption of the conformation of the C-terminal domain covering the enzyme active site. These structural changes induced by the acid treatment may open the entrance to the enzyme active site for substrate incorporation. To compare the mechanism of hydroxylation by the acid-treated tyrosinase with that by trypsin-treated tyrosinase, a detailed steady-state kinetic analysis of the phenolase activity was performed by monitoring the O(2)-consumption rate using a Clark-type oxygen electrode. The results clearly show that the phenolase activity (phenol hydroxylation) of the activated tyrosinase involves an electrophilic aromatic substitution mechanism as in the case of mushroom tyrosinase (Yamazaki and Itoh in J. Am. Chem. Soc. 125:13034-13035, 2003) and activated hemocyanin with urea (Morioka et al. in J. Am. Chem. Soc. 128:6788-6789, 2006).

  14. Mechanisms regulating brain docosahexaenoic acid uptake: what is the recent evidence?

    Science.gov (United States)

    Chouinard-Watkins, Raphaël; Lacombe, R J Scott; Bazinet, Richard P

    2018-03-01

    To summarize recent advances pertaining to the mechanisms regulating brain docosahexaenoic acid (DHA) uptake. DHA is an omega-3 polyunsaturated fatty acid highly enriched in neuronal membranes and it is implicated in several important neurological processes. However, DHA synthesis is extremely limited within the brain. There are two main plasma pools that supply the brain with DHA: the nonesterified pool and the lysophosphatidylcholine (lysoPtdCho) pool. Quantitatively, plasma nonesterified-DHA (NE-DHA) is the main contributor to brain DHA. Fatty acid transport protein 1 (FATP1) in addition to fatty acid-binding protein 5 (FABP5) are key players that regulate brain uptake of NE-DHA. However, the plasma half-life of lysoPtdCho-DHA and its brain partition coefficient are higher than those of NE-DHA after intravenous administration. The mechanisms regulating brain DHA uptake are more complicated than once believed, but recent advances provide some clarity notably by suggesting that FATP1 and FABP5 are key contributors to cellular uptake of DHA at the blood-brain barrier. Elucidating how DHA enters the brain is important as we might be able to identify methods to better deliver DHA to the brain as a potential therapeutic.

  15. Studies on the mechanical properties of woven jute fabric reinforced poly(l-lactic acid) composites

    OpenAIRE

    G.M. Arifuzzaman Khan; M. Terano; M.A. Gafur; M. Shamsul Alam

    2016-01-01

    Development of ecofriendly biocomposites to replace non-biodegradable synthetic fiber composites is the main objective of this study. To highlight the biocomposites as a perfect replacement, the plain woven jute fabric (WJF) reinforced poly(l-lactic acid) (PLLA) composites were prepared by the hot press molding method. The influence of woven structure and direction on the mechanical properties i.e. tensile, flexural and impact properties was investigated. The average tensile strength (TS), te...

  16. Mechanism of the toxicity induced by natural humic acid on human vascular endothelial cells

    OpenAIRE

    Kihara, Yusuke; Yustiawati; Tanaka, Masato; Gumiri, Sulmin; Ardianor; Hosokawa, Toshiyuki; Tanaka, Shunitz; Saito, Takeshi; Kurasaki, Masaaki

    2012-01-01

    Humic acid (HA), a group of high-molecular weight organic compounds characterized by an ability to bind heavy metals, is normally found in natural water. Although the impairment of vascular endothelial cells in the presence of humic substances has been reported to be involved in some diseases, the mechanisms responsible for this involvement remain unclear. In this study, we examined the cytotoxicity of HA obtained from peatland in Central Kalimantan, Indonesia, to human vascular endothelial c...

  17. Boron Stress Activates the General Amino Acid Control Mechanism and Inhibits Protein Synthesis

    Science.gov (United States)

    Uluisik, Irem; Kaya, Alaattin; Fomenko, Dmitri E.; Karakaya, Huseyin C.; Carlson, Bradley A.; Gladyshev, Vadim N.; Koc, Ahmet

    2011-01-01

    Boron is an essential micronutrient for plants, and it is beneficial for animals. However, at high concentrations boron is toxic to cells although the mechanism of this toxicity is not known. Atr1 has recently been identified as a boron efflux pump whose expression is upregulated in response to boron treatment. Here, we found that the expression of ATR1 is associated with expression of genes involved in amino acid biosynthesis. These mechanisms are strictly controlled by the transcription factor Gcn4 in response to boron treatment. Further analyses have shown that boron impaired protein synthesis by promoting phosphorylation of eIF2α in a Gcn2 kinase dependent manner. The uncharged tRNA binding domain (HisRS) of Gcn2 is necessary for the phosphorylation of eIF2α in the presence of boron. We postulate that boron exerts its toxic effect through activation of the general amino acid control system and inhibition of protein synthesis. Since the general amino acid control pathway is conserved among eukaryotes, this mechanism of boron toxicity may be of general importance. PMID:22114689

  18. Similar mechanisms of fatty acid transfer from human anal rodent fatty acid-binding proteins to membranes: liver, intestine, heart muscle, and adipose tissue FABPs.

    NARCIS (Netherlands)

    Storch, J.; Veerkamp, J.H.; Hsu, K.T.

    2002-01-01

    The mammalian fatty acid-binding proteins (FABPs) are thought to be important for the transport and metabolism of fatty acids in numerous cell types. The transfer of FA from different members of the FABP family to membranes has been shown to occur by two distinct mechanisms, an aqueous

  19. Characteristics and mechanism of explosive reactions of Purex solvents with Nitric Acid at elevated temperatures

    International Nuclear Information System (INIS)

    Miyata, Teijiro; Takada, Junichi; Koike, Tadao; Tsukamoto, Michio; Watanabe, Koji; Ida, Masaaki; Nakagiri, Naotaka; Nishio, Gunji

    2000-03-01

    This investigation was undertaken to make clear the energetic properties and mechanism of explosive decomposition of Purex solvent systems (TBP/n-Dodecane/HNO 3 ) by Nitric Acid at elevated temperatures using a calorimetric technique (DSC, ARC) and a chromatographic technique (GC, GC/MS). The measurement of exothermic events of solvent-HNO 3 reactions using DSC with a stainless steel sealed cell showed distinct two peaks with maxima at around 170 and 320degC, respectively. The peak at around 170degC was mainly attributed to the reactions of dealkylation products (n-butyl nitrate) of TBP and the solvent with nitric acid, and the peak at around 320degC was attributed to the exothermic decomposition of nitrated dodecanes formed in the foregoing exothermic reaction of dodecane with nitric acid. By using the data obtained in ARC experiments, activation energies of 123.2 and 152.5 kJ/mol were determined for the exothermic reaction of TBP with nitric acid and for the exothermic pyrolysis of n-butyl nitrate, respectively. Some possible pathways were considered for the explosive decomposition of TBP by nitric acid at elevated temperatures. (author)

  20. Structural aspects of catalytic mechanisms of endonucleases and their binding to nucleic acids

    Energy Technology Data Exchange (ETDEWEB)

    Zhukhlistova, N. E.; Balaev, V. V.; Lyashenko, A. V.; Lashkov, A. A., E-mail: alashkov83@gmail.com [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2012-05-15

    Endonucleases (EC 3.1) are enzymes of the hydrolase class that catalyze the hydrolytic cleavage of deoxyribonucleic and ribonucleic acids at any region of the polynucleotide chain. Endonucleases are widely used both in biotechnological processes and in veterinary medicine as antiviral agents. Medical applications of endonucleases in human cancer therapy hold promise. The results of X-ray diffraction studies of the spatial organization of endonucleases and their complexes and the mechanism of their action are analyzed and generalized. An analysis of the structural studies of this class of enzymes showed that the specific binding of enzymes to nucleic acids is characterized by interactions with nitrogen bases and the nucleotide backbone, whereas the nonspecific binding of enzymes is generally characterized by interactions only with the nucleic-acid backbone. It should be taken into account that the specificity can be modulated by metal ions and certain low-molecular-weight organic compounds. To test the hypotheses about specific and nonspecific nucleic-acid-binding proteins, it is necessary to perform additional studies of atomic-resolution three-dimensional structures of enzyme-nucleic-acid complexes by methods of structural biology.

  1. Mechanisms increasing n-3 highly unsaturated fatty acids in the heart.

    Science.gov (United States)

    Glück, Tobias; Rupp, Heinz; Alter, Peter

    2016-03-01

    Due to ambiguous findings on cardiovascular benefits of systemic omega-3 fatty acid therapy, endogenous mechanisms contributing to local organ-specific concentrations of highly unsaturated fatty acids (HUFA) were examined. Using gas chromatography, 43 fatty acids were analyzed in atrial and ventricular myocardium and in pericardial fluid of male Wistar rats. To examine the endogenous fatty acid metabolism, precursors were administered into the pericardial sac. Pro- and anti-inflammatory actions were induced by talc or fenofibrate, respectively. Physical exercise and a sedentary obese state were used for increased beta-oxidation. DHA (22:6n-3) was increased in ventricular when compared with atrial myocardium (9.0 ± 2.1% vs. 4.7 ± 1.0%, p acid (24:5n-3) in atrial myocardium, which is a key precursor of DHA. In contrast, proinflammatory stimulation of the n-6 HUFA pathway did not influence the n-3 metabolism. Exercise- and obesity-induced increased beta-oxidation, the finalizing step of DHA synthesis, was associated with increased ventricular DHA concentrations (6.7 ± 1.0% vs. 8.4 ± 1.2%, p < 0.01). It is concluded that the endogenous metabolism contributes markedly to myocardial HUFA concentrations. The findings are supposed to influence the efficacy of oral HUFA treatment and provide a rationale for divergent findings of previous trials on omega-3 therapy.

  2. Behaviors and mechanism of acid dyes sorption onto diethylenetriamine-modified native and enzymatic hydrolysis starch

    International Nuclear Information System (INIS)

    Wang Zuohua; Xiang Bo; Cheng Rumei; Li Yijiu

    2010-01-01

    In this paper, different starches were modified by diethylenetriamine. The native starch reacted with diethylenetriamine giving CAS, whereas the enzymatic hydrolysis starch was modified by diethylenetriamine producing CAES. Adsorption capacities of CAES for four acid dyes, namely, Acid orange 7 (AO7), Acid orange 10 (AO10), Acid green 25 (AG25) and Acid red 18 (AR18) have been determined to be 2.521, 1.242, 1.798 and 1.570 mmol g -1 , respectively. In all cases, CAES has exhibited higher sorption ability than CAS, and the increment for these dyes took the sequence of AO7 (0.944 mmol g -1 ) > AO10 (0.592 mmol g -1 ) > AR18 (0.411 mmol g -1 ) > AG25 (0.047 mmol g -1 ). Sorption kinetics and isotherms analysis showed that these sorption processes were better fitted to pseudo-second-order equation and Langmuir equation. Chemical sorption mechanisms were confirmed by studying the effects of pH, ionic strength and hydrogen bonding. Thermodynamic parameters of these dyes onto CAES and CAS were also observed and it indicated that these sorption processes were exothermic and spontaneous in nature.

  3. Flotation performances and adsorption mechanism of α-hydroxyoctyl phosphinic acid to cassiterite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fangxu; Zhong, Hong, E-mail: zhongh@csu.edu.cn; Zhao, Gang; Wang, Shuai; Liu, Guangyi, E-mail: guangyi.liu@163.com

    2015-10-30

    Highlights: • Flotation of cassiterite is carried out using a new collector HPA. • Phosphorous and oxygen of HPA forms chelation with Sn. • HPA exhibits good selectivity to cassiterite against magnetite and hematite. • HPA chemisorbs on cassiterite surface by form of Sn–P and Sn–O–P bond. - Abstract: In this paper, the flotation performances and adsorption mechanism of α-hydroxyoctyl phosphinic acid (HPA) to cassiterite were investigated by adsorption experiments, micro-flotation tests, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The micro-flotation results indicated that compared with styrene phosphonic acid (SPA), diphosphonic acid (DPA), benzohydroxamic acid (BHA) and salicylhydroxamic acid (SHA), HPA exhibited excellent collecting power to cassiterite and superior selectivity against magnetite or hematite over a wide pH range. The results of adsorption experiments and zeta potential deduced that HPA chemisorb on cassiterite surfaces. The results of FTIR inferred HPA chemisorb onto cassiterite surfaces through its P and O atoms with the P–H and O–H bonds broken. XPS analysis further demonstrated HPA react with Sn species by formation of Sn–O–P and Sn–P bond.

  4. [Forming mechanism of humic acid-kaolin complexes and the adsorption of trichloroethylene].

    Science.gov (United States)

    Zhu, Xiao-jing; He, Jiang-tao; Su, Si-hui

    2015-01-01

    The interaction between soil organic components and mineral components was explored in this study. Humic acid and kaolin were used for the preparation of organic-mineral complexes with different contents of organic matter, for experimental study of the adsorption of trichloroethylene. The results showed that the adsorption of trichlorethylene fitted the Freundlich isotherm model. The existence of interaction between humic acid and kaolin was indicated by the significant difference between the actual value and the theoretically overlaid value of the adsorption capacity. With various characterizations, such as FTIR and surface area & pore analysis, the mechanism of interaction between humic acid and kaolin was suggested as follows. When their contents were low, humic acid molecules firstly loaded on the surface binding sites of kaolin. Then with the content increased, as O/M( organic-mineral mass ratio) was 0.02-0.04, some surface pores of kaolin were filled by part of the molecules. After reaching a relatively stable stage, as O/M was 0.04-0.08, humic molecules continued to load on the surface of kaolin and formed the first humic molecule-layer. With humic acid content continued increasing, as O/M was 0.08-0.10, more humic molecules attached to kaolin surface through the interaction with the first layer of molecules and then formed the second layer. O/M was 0.10-0.16 as the whole second layer stage, meanwhile the first layer was compressed. Then when O/M was 0.16-0.4, there were still some humic loadings onto the second layer as the third layer, and further compressed the inner humic acid layers. Besides, some humic acid molecules or aggregates might go on attaching to form as further outer layer.

  5. Modulation of hematopoiesis and survival after high-dose chemotherapy or radiotherapy: review and discussion of possible mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Boggs, S.S.; Boggs, D.R.

    1979-01-01

    This paper reviews ways by which growth of transplanted or surviving hematopoietic stem cells might be enhanced to improve survival in the case of autologous marrow transplantation. Most of the treatments known to have such effects have been used in isologous mouse models and improve animal survival by enhancing hematopoietic recovery after high doses of whole body irradiation or chemotherapy. Although some of these were studied 20 years ago, the use of such treatments in man has awaited the realization that some disseminated cancer can only be eliminated by use of various treatments where hematopoietic damage is the limiting factor. Although increasing the number of transplanted pluripotent stem cells is the most certain way to hasten return of needed blood cells in transplant patients, several of the treatments listed in the paper have growth enhancing effects on both surviving host stem cells and transplanted cells. There are recent studies which indicate that such priming treatments may also be effective in other normal tissues such as gut and bladder epithelium. At least one study in man has intentionally applied this approach with the expected benefit and others may have done so inadvertently. Much work remains to find new combinations to select the best priming treatments and intervals in man and to determine whether or not such treatments are effective against tumors.

  6. Nurr1 protein is required for N-methyl-D-aspartic acid (NMDA) receptor-mediated neuronal survival.

    Science.gov (United States)

    Barneda-Zahonero, Bruna; Servitja, Joan-Marc; Badiola, Nahuai; Miñano-Molina, Alfredo J; Fadó, Rut; Saura, Carlos A; Rodríguez-Alvarez, José

    2012-03-30

    NMDA receptor (NMDAR) stimulation promotes neuronal survival during brain development. Cerebellar granule cells (CGCs) need NMDAR stimulation to survive and develop. These neurons differentiate and mature during its migration from the external granular layer to the internal granular layer, and lack of excitatory inputs triggers their apoptotic death. It is possible to mimic this process in vitro by culturing CGCs in low KCl concentrations (5 mm) in the presence or absence of NMDA. Using this experimental approach, we have obtained whole genome expression profiles after 3 and 8 h of NMDA addition to identify genes involved in NMDA-mediated survival of CGCs. One of the identified genes was Nurr1, a member of the orphan nuclear receptor subfamily Nr4a. Our results report a direct regulation of Nurr1 by CREB after NMDAR stimulation. ChIP assay confirmed CREB binding to Nurr1 promoter, whereas CREB shRNA blocked NMDA-mediated increase in Nurr1 expression. Moreover, we show that Nurr1 is important for NMDAR survival effect. We show that Nurr1 binds to Bdnf promoter IV and that silencing Nurr1 by shRNA leads to a decrease in brain-derived neurotrophic factor (BDNF) protein levels and a reduction of NMDA neuroprotective effect. Also, we report that Nurr1 and BDNF show a similar expression pattern during postnatal cerebellar development. Thus, we conclude that Nurr1 is a downstream target of CREB and that it is responsible for the NMDA-mediated increase in BDNF, which is necessary for the NMDA-mediated prosurvival effect on neurons.

  7. Unravelling the resistance mechanisms to 2,4-D (2,4-dichlorophenoxyacetic acid) in corn poppy (Papaver rhoeas).

    Science.gov (United States)

    Rey-Caballero, Jordi; Menéndez, Julio; Giné-Bordonaba, Jordi; Salas, Marisa; Alcántara, Ricardo; Torra, Joel

    2016-10-01

    In southern Europe, the intensive use of 2,4-D (2,4-dichlorophenoxyacetic acid) and tribenuron-methyl in cereal crop systems has resulted in the evolution of resistant (R) corn poppy (Papaver rhoeas L.) biotypes. Experiments were conducted to elucidate (1) the resistance response to these two herbicides, (2) the cross-resistant pattern to other synthetic auxins and (3) the physiological basis of the auxin resistance in two R (F-R213 and D-R703) populations. R plants were resistant to both 2,4-D and tribenuron-methyl (F-R213) or just to 2,4-D (D-R703) and both R populations were also resistant to dicamba and aminopyralid. Results from absorption and translocation experiment revealed that R plants translocated less [14C]-2,4-D than S plants at all evaluation times. There was between four and eight-fold greater ethylene production in S plants treated with 2,4-D, than in R plants. Overall, these results suggest that reduced 2,4-D translocation is the resistance mechanism in synthetic auxins R corn poppy populations and this likely leads to less ethylene production and greater survival in R plants. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Interaction of ATP with acid-denatured cytochrome c via coupled folding-binding mechanism

    International Nuclear Information System (INIS)

    Ahluwalia, Unnati; Deep, Shashank

    2012-01-01

    Highlights: ► Interaction between ATP and cyt c takes place via coupled binding–folding mechanism. ► Binding of ATP to cyt c is endothermic. ► GTP and CTP induce similar level of helicity in acid-denatured cyt c as with ATP. ► Compactness induced by ATP is far greater than ADP or AMP. - Abstract: The non-native conformations of the cytochrome c (cyt c) are believed to play key roles in a number of physiological processes. Nucleotides are supposed to act as allosteric effectors in these processes by regulating structural transitions among different conformations of cyt c. To understand the interaction between acid denatured cytochrome c and nucleotides, spectroscopic and calorimetric techniques were utilized to observe the structural features of the induced conformation and the energetics of interaction of acid denatured cyt c with different nucleotides. Structure induction in the acid denatured cyt c was observed on the addition of the ∼1 mM nucleotide tri-phosphates (ATP/GTP/CTP) at 25 °C, however, not in the presence of 1 mM nucleotide mono and diphosphates. ATP-bound cyt c at pH 2.0 is likely to have a conformation that has intact α-helical domain. However, Met80-Fe(III) axial bond is still ruptured. Observed thermodynamics reflect interaction between nucleotide and cyt c via coupled binding–folding mechanism. DSC data suggest the preferential binding of the ATP to the folded conformation with respect to the acid denatured cyt c. ITC data indicate that the exothermic folding of cyt c was accompanied by endothermic binding of ATP to cyt c.

  9. Depletion of retinoic acid receptors initiates a novel positive feedback mechanism that promotes teratogenic increases in retinoic acid.

    Directory of Open Access Journals (Sweden)

    Enrico D'Aniello

    Full Text Available Normal embryonic development and tissue homeostasis require precise levels of retinoic acid (RA signaling. Despite the importance of appropriate embryonic RA signaling levels, the mechanisms underlying congenital defects due to perturbations of RA signaling are not completely understood. Here, we report that zebrafish embryos deficient for RA receptor αb1 (RARαb1, a conserved RAR splice variant, have enlarged hearts with increased cardiomyocyte (CM specification, which are surprisingly the consequence of increased RA signaling. Importantly, depletion of RARαb2 or concurrent depletion of RARαb1 and RARαb2 also results in increased RA signaling, suggesting this effect is a broader consequence of RAR depletion. Concurrent depletion of RARαb1 and Cyp26a1, an enzyme that facilitates degradation of RA, and employment of a novel transgenic RA sensor line support the hypothesis that the increases in RA signaling in RAR deficient embryos are the result of increased embryonic RA coupled with compensatory RAR expression. Our results support an intriguing novel mechanism by which depletion of RARs elicits a previously unrecognized positive feedback loop that can result in developmental defects due to teratogenic increases in embryonic RA.

  10. The effect of electron beam irradiation, combined with acetic acid, on the survival and recovery of Escherichia coli and Lactobacillus curvatus

    International Nuclear Information System (INIS)

    Fielding, L.M.; Cook, P.E.; Grandison, A.S.

    1997-01-01

    The preservation of food by ionising radiation may lead to undesirable sensory changes within the food. These changes can be reduced by combining irradiation with other treatments, for example the addition of organic acids. Late exponential phase cultures of Escherichia coli and Lactobacillus curvatus were irradiated, in a liquid medium, at doses of 0-1.8 kilograys (kGy), in the presence of acetic acid (0-2%) at pH 4.6. A synergistic effect occurred when E. coli was irradiated in the presence of acetic acid (0.02-1.0%) at all doses used (0.145-1.1 kGy). There is evidence to suggest that membrane disruption occurred in the cells as a result of the combined treatments and this may account, to some extent, for the synergism observed. The addition of acetic acid up to a concentration of 2.0% had no effect upon the radiation survival or upon the subsequent growth of L. curvatus

  11. Effect of organic acids and marination ingredients on the survival of Campylobacter jejuni on meat

    DEFF Research Database (Denmark)

    Birk, Tina; Grønlund, Anne Christine Jørgensen; Christensen, Bjarke Bak

    2010-01-01

    inoculated in brain heart infusion broth containing 0.3% tartaric acid. On chicken meat medallions, reductions of C. jejuni were 0.5 to 2 log units when tartaric acid solutions (2, 4, 6, and 10%) were spread onto the meat. Analysis of acidic food ingredient (e.g., vinegar, lemon juice, pomegranate syrup......, and soya sauce) revealed that such ingredients reduced counts of C. jejuni by at least 0.8 log units on meat medallions. Three low pH marinades (pH lemon juice, and white wine vinegar were prepared. When applied to whole filets, these marinades resulted in a reduction...... ingredients at 4°C in broth and on chicken meat. The organic acids (0.5%) reduced populations of C. jejuni in broth (chicken juice and brain heart infusion broth) by 4 to 6 log units (after 24 h); tartaric acid was the most efficient treatment. Large strain variation was observed among 14 C. jejuni isolates...

  12. Decrease of intracellular pH as possible mechanism of embryotoxicity of glycol ether alkoxyacetic acid metabolites

    International Nuclear Information System (INIS)

    Louisse, Jochem; Bai Yanqing; Verwei, Miriam; Sandt, Johannes J.M. van de; Blaauboer, Bas J.; Rietjens, Ivonne M.C.M.

    2010-01-01

    Embryotoxicity of glycol ethers is caused by their alkoxyacetic acid metabolites, but the mechanism underlying the embryotoxicity of these acid metabolites is so far not known. The present study investigates a possible mechanism underlying the embryotoxicity of glycol ether alkoxyacetic acid metabolites using the methoxyacetic acid (MAA) metabolite of ethylene glycol monomethyl ether as the model compound. The results obtained demonstrate an MAA-induced decrease of the intracellular pH (pH i ) of embryonic BALB/c-3T3 cells as well as of embryonic stem (ES)-D3 cells, at concentrations that affect ES-D3 cell differentiation. These results suggest a mechanism for MAA-mediated embryotoxicity similar to the mechanism of embryotoxicity of the drugs valproic acid and acetazolamide (ACZ), known to decrease the pH i in vivo, and therefore used as positive controls. The embryotoxic alkoxyacetic acid metabolites ethoxyacetic acid, butoxyacetic acid and phenoxyacetic acid also caused an intracellular acidification of BALB/c-3T3 cells at concentrations that are known to inhibit ES-D3 cell differentiation. Two other embryotoxic compounds, all-trans-retinoic acid and 5-fluorouracil, did not decrease the pH i of embryonic cells at concentrations that affect ES-D3 cell differentiation, pointing at a different mechanism of embryotoxicity of these compounds. MAA and ACZ induced a concentration-dependent inhibition of ES-D3 cell differentiation, which was enhanced by amiloride, an inhibitor of the Na + /H + -antiporter, corroborating an important role of the pH i in the embryotoxic mechanism of both compounds. Together, the results presented indicate that a decrease of the pH i may be the mechanism of embryotoxicity of the alkoxyacetic acid metabolites of the glycol ethers.

  13. Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere

    DEFF Research Database (Denmark)

    Smigic, Nada; Rajkovic, Andreja; Nielsen, Dennis Sandris

    2010-01-01

    Campylobacter jejuni cells treated with lactic acid (LA, 3% lactic acid, pH 4.0, 2 min) or chlorine dioxide (ClO(2), 20 ppm, 2 min) were inoculated in Bolton broth (pH 6.0) and incubated under 80% O(2)/20% N(2), 80% CO(2)/20% N(2), air or micro-aerophilic (10% CO(2)/85% N(2)/5% O(2)) atmosphere, at 4 degrees C...... during 7 days. Treatment with water served as a control. The most suppressive atmosphere for the survival of C. jejuni was O(2)-rich atmosphere, followed by air, micro-aerophilic and CO(2)-rich atmosphere. The survival of C. jejuni was dependent on the type of initial decontamination treatment...... on their pH(i) values. The pH(i) response was independent on the surrounding atmosphere since similar distribution of the subpopulations was observed for all tested atmospheres. However, the pH(i) response was dependent on the initial decontamination treatment. The investigation of intracellular parameters...

  14. Assessing the survival of MRC5 and a549 cell lines upon exposure to pyruvic Acid, sodium citrate and sodium bicarbonate - biomed 2013.

    Science.gov (United States)

    Farah, Ibrahim O; Lewis, Veshell L; Ayensu, Wellington K; Cameron, Joseph A

    2013-01-01

    Lung cancer is among the most prevalent and deadly cancers in United States. In general, cancer cells are known to exhibit higher rates of glycolysis in comparison to normal cells. In attempting to exploit this unique cancer-dependent ATP generation phenomenon, it was our hypothesis that upon exposure to organic inhibitors of glycolysis, cancer cells would not survive normally and that their growth and viability would be vastly decreased; essential glycolytic ATP production will be exhausted to the point of collapsing energy utilization. Furthermore, we hypothesize that no negative effect would be seen with exposures to organic inhibitors for normal lung cells. The human lung fibroblast MRC-5 and the human A549 alveolar epithelial cell lines were used as in vitro models of normal lung and lung cancers respectively. Using standard methods, both cell lines were maintained and exposed to pyruvic acid, sodium citrate and sodium bicarbonate reagents at concentration levels ranging from 31.3-2,000 µg/ml in 96 well plates in quadruplets and experiments repeated at least three times using MTT, and cell counting (T4 Cellometer) assays as well as phase-contrast photo-imaging for parallel morphological displays of any changes in the course of their vitality and metabolic activities. Our results indicate that exposure of both cell lines to these organics resulted in concentration dependent cell destruction/cell survival depending on the cell line exposed. Pyruvic acid, sodium citrate and sodium bicarbonate showed statistically significant (pcancer biotherapeutics.

  15. d-Lysergic Acid Diethylamide (LSD as a Model of Psychosis: Mechanism of Action and Pharmacology

    Directory of Open Access Journals (Sweden)

    Danilo De Gregorio

    2016-11-01

    Full Text Available d-Lysergic Acid Diethylamide (LSD is known for its hallucinogenic properties and psychotic-like symptoms, especially at high doses. It is indeed used as a pharmacological model of psychosis in preclinical research. The goal of this review was to understand the mechanism of action of psychotic-like effects of LSD. We searched Pubmed, Web of Science, Scopus, Google Scholar and articles’ reference lists for preclinical studies regarding the mechanism of action involved in the psychotic-like effects induced by LSD. LSD’s mechanism of action is pleiotropic, primarily mediated by the serotonergic system in the Dorsal Raphe, binding the 5-HT2A receptor as a partial agonist and 5-HT1A as an agonist. LSD also modulates the Ventral Tegmental Area, at higher doses, by stimulating dopamine D2, Trace Amine Associate receptor 1 (TAAR1 and 5-HT2A. More studies clarifying the mechanism of action of the psychotic-like symptoms or psychosis induced by LSD in humans are needed. LSD’s effects are mediated by a pleiotropic mechanism involving serotonergic, dopaminergic, and glutamatergic neurotransmission. Thus, the LSD-induced psychosis is a useful model to test the therapeutic efficacy of potential novel antipsychotic drugs, particularly drugs with dual serotonergic and dopaminergic (DA mechanism or acting on TAAR1 receptors.

  16. d-Lysergic Acid Diethylamide (LSD) as a Model of Psychosis: Mechanism of Action and Pharmacology.

    Science.gov (United States)

    De Gregorio, Danilo; Comai, Stefano; Posa, Luca; Gobbi, Gabriella

    2016-11-23

    d-Lysergic Acid Diethylamide (LSD) is known for its hallucinogenic properties and psychotic-like symptoms, especially at high doses. It is indeed used as a pharmacological model of psychosis in preclinical research. The goal of this review was to understand the mechanism of action of psychotic-like effects of LSD. We searched Pubmed, Web of Science, Scopus, Google Scholar and articles' reference lists for preclinical studies regarding the mechanism of action involved in the psychotic-like effects induced by LSD. LSD's mechanism of action is pleiotropic, primarily mediated by the serotonergic system in the Dorsal Raphe, binding the 5-HT 2A receptor as a partial agonist and 5-HT 1A as an agonist. LSD also modulates the Ventral Tegmental Area, at higher doses, by stimulating dopamine D₂, Trace Amine Associate receptor 1 (TAAR₁) and 5-HT 2A . More studies clarifying the mechanism of action of the psychotic-like symptoms or psychosis induced by LSD in humans are needed. LSD's effects are mediated by a pleiotropic mechanism involving serotonergic, dopaminergic, and glutamatergic neurotransmission. Thus, the LSD-induced psychosis is a useful model to test the therapeutic efficacy of potential novel antipsychotic drugs, particularly drugs with dual serotonergic and dopaminergic (DA) mechanism or acting on TAAR₁ receptors.

  17. Gastroprotective mechanisms of centipedic acid, a natural diterpene from Egletes viscosa LESS.

    Science.gov (United States)

    Guedes, Marjorie Moreira; Carvalho, Ana Carla da Silva; Lima, Alana Fontales; Lira, Silveria Regina de Sousa; de Queiroz, Samia Sousa; Silveira, Edilberto Rocha; Santos, Flávia Almeida; Rao, Vietla Satyanarayana

    2008-07-01

    This study was aimed to clarify the mechanisms of gastroprotection by centipedic acid (CPA), a natural diterpene from Egletes viscosa LESS. (Asteraceae) using ethanol-induced gastric mucosal damage in mice and gastric secretion in 4-h pylorus-ligated rats as model systems. In mice, intragastrically administered CPA (25, 50, 100 mg/kg) greatly reduced the mucosal lesions induced by 96% ethanol (0.2 ml, p.o.) by 18, 53, and 79%, respectively, whereas N-acetylcysteine (NAC, 300 mg/kg, i.p.), the reference compound produced a 50% inhibition. In 4-h pylorus-ligated rats, CPA (50 mg/kg) applied intraduodenally decreased both gastric secretory volume and total acidity. Similar to NAC, the plant diterpene effectively prevented the ethanol associated decrease in non-proteic sulfhydryls (NP-SH) and the elevated thiobarbituric acid-reactive substances (TBARS) in gastric tissue, suggesting that these compounds exert an antioxidant effect. Pretreatment of mice with indomethacin, the cyclooxygenase inhibitor but not with capsazepine, the transient receptor potential vanilloid-1 (TRPV1)-receptor antagonist greatly suppressed the gastroprotective effect of CPA. Furthermore, CPA gastroprotection was significantly attenuated in mice pretreated with L-NAME or glibenclamide the respective inhibitors of nitric oxide synthase and K(+)(ATP) channel activation. These data suggest that CPA affords gastroprotection by different and complementary mechanisms, which include a sparing effect on NP-SH reserve, and roles for endogenous prostaglandins, nitric oxide, and TRPV1-receptor and K(+)(ATP) channel activation.

  18. Design and Mechanism of Tetrahydrothiophene-Based γ-Aminobutyric Acid Aminotransferase Inactivators

    Energy Technology Data Exchange (ETDEWEB)

    Le, Hoang V. [Departments; Hawker, Dustin D. [Departments; Wu, Rui [Department; Doud, Emma [Departments; Widom, Julia [Departments; Sanishvili, Ruslan [X-ray; Liu, Dali [Department; Kelleher, Neil L. [Departments; Silverman, Richard B. [Departments

    2015-03-25

    Low levels of gamma-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinsons disease, Alzheimers disease, Huntingtons disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the bloodbrain barrier and inhibit the activity of gamma-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a pi-pi interaction with Phe-189, and a weak nonbonded (SO)-O-...=C interaction with Glu-270, thereby inactivating the enzyme.

  19. In vivo expression technology and signature-tagged mutagenesis screens for identifying mechanisms of survival of zoonotic foodborne pathogens.

    Science.gov (United States)

    Dudley, Edward G

    2008-08-01

    High-throughput genetic screens provide great insights into the biochemistry and molecular biology of how bacteria sense, respond to, and propagate within their environments. Genomics era techniques such as microarrays and proteomics have great potential to increase our understanding of how foodborne pathogens grow and survive within animal and human hosts, in the environment and foods, and during thermal and nonthermal inactivation protocols. While these techniques are incredibly useful for studying gene expression in simplified in vitro conditions, it is much more challenging to pursue similar studies within more complex experimental models such as in vivo, within the food matrix, or within heterogeneous microbial populations. Techniques such as in vivo expression technology (IVET) and signature-tagged mutagenesis (STM) provide alternatives for studying bacterial gene expression and growth requirements within these settings. These techniques are used extensively by the medical, veterinary, and plant research communities for identifying genes promoting the colonization and disease process, factors mediating commensalism between bacteria and their host, and genes that promote survival of environmental bacteria within natural settings. Research into the transmission and survival of foodborne pathogens from farm-to-fork would likely benefit from these techniques, however there are few reports describing their use for such purposes. This review will briefly cover the methods of IVET and STM, discuss how these techniques improved our understanding of the interactions between zoonotic foodborne pathogens and their animal hosts, and ask whether these techniques could be further exploited to better understand the survival of foodborne pathogens within the environment, within food matrices, and during inactivation protocols.

  20. Thermal- and photo-induced degradation of perfluorinated carboxylic acids: Kinetics and mechanism.

    Science.gov (United States)

    Liu, Jiaoqin; Qu, Ruijuan; Wang, Zunyao; Mendoza-Sanchez, Itza; Sharma, Virender K

    2017-12-01

    Perfluorinated carboxylic acids (PFCAs) of different carbon chain lengths are chemicals of concern to human health and their removal, using conventional remediation technologies, is challenging. The present paper pursuits thermal and photo-induced degradation of PFCAs (F(CF 2 ) n COOH, n = 1-9) under various concentrations of four different acids (HNO 3 , H 2 SO 4 , HCl, and H 3 PO 4 ) covering a range of strong acidic to basic pH. For thermal-induced experiments, the temperature was set at 40 °C, 60 °C, and 80 °C at acid strengths of 0.04-18.4 M. Photo-induced experiments were conducted at pH 0.5, 7.0, and 13.0 under a light intensity of (150 ± 10) × 100 μW/cm 2 . The degradation first-order rate constant (k 1, h -1 ) as a function of [H + ] was modeled by considering equilibrium of nondissociated (F(CF 2 ) n COOH, HX) and dissociated (F(CF 2 ) n COO - , X - ) species of PFCAs (HX ⇌ X -  + H + , pK a  = -0.1). Species-specific rate constants, k 1 HX , reasonably described the trend of thermal and photo decay of PFCAs, where k 1 HX increased with acidity of solution and the carbon chain length of PFCAs. Mechanism of degradation of PFCAs (e.g. perfluorooctanoic acid (PFOA)) involved homolytic breakage of CC bond between alkyl and carboxyl groups, which produced radicals and subsequently decarboxylation to perfluoroheptene-1. Density functional theory (DFT) calculations supported the mechanism. The calculations indicated that a breaking of CC bond is more feasible with nondissociated HX than dissociated X - species of PFCAs and also with increase in chain length. The potential of a combination of thermal- and photo-induced processes under acidic conditions to enhance degradation of PFOA in water is presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. l-Arginine Uptake by Cationic Amino Acid Transporter Promotes Intra-Macrophage Survival of Leishmania donovani by Enhancing Arginase-Mediated Polyamine Synthesis

    Science.gov (United States)

    Mandal, Abhishek; Das, Sushmita; Kumar, Ajay; Roy, Saptarshi; Verma, Sudha; Ghosh, Ayan Kumar; Singh, Ruby; Abhishek, Kumar; Saini, Savita; Sardar, Abul Hasan; Purkait, Bidyut; Kumar, Ashish; Mandal, Chitra; Das, Pradeep

    2017-01-01

    The survival of intracellular protozoan parasite, Leishmania donovani, the causative agent of Indian visceral leishmaniasis (VL), depends on the activation status of macrophages. l-Arginine, a semi-essential amino acid plays a crucial regulatory role for activation of macrophages. However, the role of l-arginine transport in VL still remains elusive. In this study, we demonstrated that intra-macrophage survival of L. donovani depends on the availability of extracellular l-arginine. Infection of THP-1-derived macrophage/human monocyte-derived macrophage (hMDM) with Leishmania, resulted in upregulation of l-arginine transport. While investigating the involvement of the transporters, we observed that Leishmania survival was greatly impaired when the transporters were blocked either using inhibitor or siRNA-mediated downregulation. CAT-2 was found to be the main isoform associated with l-arginine transport in L. donovani-infected macrophages. l-arginine availability and its transport regulated the host arginase in Leishmania infection. Arginase and inducible nitric oxide synthase (iNOS) expression were reciprocally regulated when assayed using specific inhibitors and siRNA-mediated downregulation. Interestingly, induction of iNOS expression and nitric oxide production were observed in case of inhibition of arginase in infected macrophages. Furthermore, inhibition of l-arginine transport as well as arginase resulted in decreased polyamine production, limiting parasite survival inside macrophages. l-arginine availability and transport regulated Th1/Th2 cytokine levels in case of Leishmania infection. Upregulation of l-arginine transport, induction of host arginase, and enhanced polyamine production were correlated with increased level of IL-10 and decreased level of IL-12 and TNF-α in L. donovani-infected macrophages. Our findings provide clear evidence for targeting the metabolism of l-arginine and l-arginine-metabolizing enzymes as an important therapeutic and

  2. Effect of carboxylic acids as compatibilizer agent on mechanical properties of thermoplastic starch and polypropylene blends.

    Science.gov (United States)

    Martins, Andréa Bercini; Santana, Ruth Marlene Campomanes

    2016-01-01

    In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA). The effects of NCA on the mechanical, physical, thermal and morphological properties of PP/TPS blends were investigated and compared against PP/TPS with and without PP-grafted maleic anhydride (PPgMA). When compared to PP/TPS, blends with C18, PPgMA and C14 presented an improvement of 25, 22 and 17% in tensile strength at break and of 180, 194 and 259% in elongation at break, respectively. The highest increase, 54%, in the impact strength was achieved with C14 incorporation. Improvements could be seen, through scanning electron microscopy (SEM) images, in the compatibility between the immiscible components by acids incorporation. These results showed that carboxylic acids, specifically C14, could be used as compatibilizer agent and could substitute PPgMA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Kinetics and Mechanism of Oxidation of Methimazole by Chlorite in Slightly Acidic Media.

    Science.gov (United States)

    Chipiso, Kudzanai; Simoyi, Reuben H

    2016-06-02

    The kinetics and mechanism of the oxidation of methimazole (1-methyl-3H-imidazole), MMI, by chlorite in mildly acidic environments were studied. It is a complex reaction that gives oligo-oscillations in chlorine dioxide concentrations in excess chlorite conditions. The stoichiometry is strictly 2:1, with the sulfur center being oxidized to sulfate and the organic moiety being hydrolyzed to several indeterminate species. In excess MMI conditions over chlorite, the sulfinic acid and sulfonic acid were observed as major intermediates. The sulfenic acid, which was observed in the electrochemical oxidation of MMI, was not observed with chlorite oxidations. Initial reduction of chlorite produced HOCl, an autocatalytic species in chlorite oxidations. HOCl rapidly reacts with chlorite to produce chlorine dioxide, which, in turn, reacts rapidly with MMI to produce more chlorite. The reaction of chlorine dioxide with MMI is competitive, in rate, with the chlorite-MMI and HOCl-ClO2(-) reactions. This explains the oligo-oscillations in ClO2 concentrations.

  4. Genome‐wide identification of tolerance mechanisms toward p‐coumaric acid in Pseudomonas putida

    Science.gov (United States)

    Calero, Patricia; Jensen, Sheila I.; Bojanovič, Klara; Lennen, Rebecca M.; Koza, Anna

    2017-01-01

    Abstract The soil bacterium Pseudomonas putida KT2440 has gained increasing biotechnological interest due to its ability to tolerate different types of stress. Here, the tolerance of P. putida KT2440 toward eleven toxic chemical compounds was investigated. P. putida was found to be significantly more tolerant toward three of the eleven compounds when compared to Escherichia coli. Increased tolerance was for example found toward p‐coumaric acid, an interesting precursor for polymerization with a significant industrial relevance. The tolerance mechanism was therefore investigated using the genome‐wide approach, Tn‐seq. Libraries containing a large number of miniTn5‐Km transposon insertion mutants were grown in the presence and absence of p‐coumaric acid, and the enrichment or depletion of mutants was quantified by high‐throughput sequencing. Several genes, including the ABC transporter Ttg2ABC and the cytochrome c maturation system (ccm), were identified to play an important role in the tolerance toward p‐coumaric acid of this bacterium. Most of the identified genes were involved in membrane stability, suggesting that tolerance toward p‐coumaric acid is related to transport and membrane integrity. PMID:29131301

  5. Antimicrobial effects of weak acids on the survival of Escherichia coli O157:H7 under anaerobic conditions

    Science.gov (United States)

    Outbreaks of disease due to vegetative bacterial pathogens associated with acid foods (such as apple cider) have raised concerns about acidified vegetables and related products that have a similar pH (3.2 to 4.0). Escherichia coli O157:H7 and related strains of enterohemorrhagic E. coli (EHEC) have ...

  6. THE EFFECT OF CAROVERINE AND ITS COMBINATION WITH AMINOOXYACETIC ACID ON SURVIVAL TIME OF MICE WITH EXPERIMENTAL TETANUS

    Directory of Open Access Journals (Sweden)

    Indira Mujezinović

    2013-03-01

    Full Text Available Tetanus is a disease that occurs in humans and various animal species worldwide. Tetanus toxin, after binding itself to nerve structures in the spinal cord, blocking the release of inhibitory transmitors which results in predominance of excitatory transmitors, and this manifestes itself in skeletal muscle spasm. In theory, inhibition of excitatory transmission can try to antagonize a number of ways: by stimulating inhibitory transmission with application inhibitory transmitors, inhibition of excitatory transmission by application of antagonists of excitatory transmitors and combination of antagonists of excitatory transmitors. Bearing this in mind, we attempted to normalize the disorders by tetanus toxin with the use of caroverine, an antagonist of excitatory transmitors, alone and in combination with aminooxyacetic acid (substance that increases the level of GABA. Experiments were conducted on albino mice of both sexes, weight 20-25 g. The experimental tetanus was induced by application of tetanus toxin. The application of caroverine and combination with aminooxyacetic acid was carried out 24 hours after application of tetanus toxin, once per day, until the death. Caroverine, given alone in a dose of 1,2 mg/kg significantly prolonged the LD50 period of mice with experimental tetanus, so the obtained results can be said that its application only at this dose proved to be effective. The combination with aminooxyacetic acid was gave an insignificant extension of mice’s dying time with experimental tetanus in the trial, compared to the control group. Key words: tetanus, tetanus toxin, transmitors, caroverine, aminooxyacetic acid

  7. Kinetics and Mechanism of Electron Transfer Reaction: Oxidation of Sulfanilic Acid by N-Chloro-p-Toluene Sulfonamide in Acid Perchlorate Medium

    International Nuclear Information System (INIS)

    Sailani, Riya; Bhasin, Meneka; Khandelwal, C. L.; Sharma, P. D.

    2014-01-01

    The kinetics and mechanism of oxidation of sulfanilic acid by N-chloro-p-toluene sulfonamide (chloramine-T) have been studied in acid medium. The species of chloramine-T were analysed on the basis of experimental observations and predominantly reactive species was taken into account for proposition of most plausible reaction mechanism. The derived rate law (1) conforms to such a mechanism. All kinetic parameters were evaluated. Activation parameters such as energy and entropy of activation were calculated to be (61.67 ± 0.47) kJ mol -1 and (-62.71 ± 2.48) JK -1 mol -1 respectively employing Eyring equation

  8. SEPARATION OF p-AMINOBENZOIC ACID BY REACTIVE EXTRACTION. 1. MECHANISM AND INFLUENCING FACTORS

    Directory of Open Access Journals (Sweden)

    DAN CASCAVAL

    2008-09-01

    Full Text Available The comparative study on the reactive extraction of p-aminobenzoic acid with Amberlite LA-2 and D2EHPA in two solvents with different polarity (n-heptane and dichloromethane indicated that the extractant type and solvent polarity control the extraction mechanism. Thus, the reactive extraction with Amberlite LA-2 occurs by means of the interfacial formation of an aminic adduct with three extractant molecules in low-polar solvent, or of an salt with one extractant molecule in higher polar solvent. Similarly, the extraction with D2EHPA is based on the formation of an acidic adduct with two extractant molecules in n-heptane, or of a salt with one extractant molecule in dichloromethane. The most efficient extraction has been reached for the combination Amberlite LA-2-dichloromethane.

  9. Mechanical characterization of porous asphalt mixes modified with fatty acid amides -FAA-

    Directory of Open Access Journals (Sweden)

    Vanessa Senior Arrieta

    2017-01-01

    Full Text Available Porous asphalt mixes (PAM, form a special road surface for asphalt pavement structures, have a special particle size distribution that lets infiltrate to the runoff storm water through of it because of its voids content about 20 %. Many researchers conducted studies and have concluded that the use of modified asphalts is completely necessary to design PAM. Organic and chemical additives and special procedures as foamed asphalt have enhanced the performance of PAM, during their service life. This paper is focused on the mechanical characterization of PAM and how the asphalt modified with fatty acid amides, influenced on their behavior and performance. Based on an experimental methodology with laboratory tests aimed at establishing a comparison between porous asphalt mixes, using for its design and production a penetration 60-70 pure asphalt and another one asphalt modified with fatty acid amides.

  10. Identification of lactic acid bacteria in the rumen and feces of dairy cows fed total mixed ration silage to assess the survival of silage bacteria in the gut.

    Science.gov (United States)

    Han, H; Ogata, Y; Yamamoto, Y; Nagao, S; Nishino, N

    2014-09-01

    The survival of silage lactic acid bacteria (LAB) in the gut of dairy cows was evaluated by examining the LAB communities of silage and gut contents. Samples were collected at 2 different research institutes (Mie and Okayama) that offered total mixed ration (TMR) silage throughout the year. Silage and feces were sampled in August, October, and November at the Mie institute, whereas silage, rumen fluid, and feces were sampled in June and August at the Okayama institute. Denaturing gradient gel electrophoresis using Lactobacillus-specific primers was performed to detect LAB species in the samples. The selected bands were purified for species identification and the band patterns were used for principal component analysis. Lactic acid was the predominant fermentation product in all the TMR silages analyzed, and the lactic acid level tended to be constant regardless of the sampling time and region. A total of 14 LAB species were detected in the TMR silage samples, of which 5 (Lactobacillus acetotolerans, Lactobacillus pontis, Lactobacillus casei, Lactobacillus suebicus, and Lactobacillus plantarum) were detected in the dairy cow feces. Most of the denaturing gradient gel electrophoresis bands for the feces samples were also detected in the rumen fluid, suggesting that any elimination of silage LAB occurred in the rumen and not in the postruminal gut segments. The principal component analysis indicated that the LAB communities in the silage, rumen fluid, and feces were separately grouped; hence, the survival of silage LAB in the cow rumen and lower gut was deemed difficult. It was concluded that, although the gut LAB community is robust and not easily affected by the silage conditions, several LAB species can inhabit both silage and feces, which suggests the potential of using silage as a vehicle for conveying probiotics. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. Isotopic study on mechanism for skeletal isomerization of n-butane over solid acids

    International Nuclear Information System (INIS)

    Suzuki, Tetsuo; Okuhara, Toshio

    2000-01-01

    Reaction mechanism for skeletal isomerization of n-butane over typical strong solid acids were investigated by using 1,4- 13 C 2 -n-butane. We used FI MASS for the analysis of 13 C distribution to get the parent pattern. 13 C-distribution of isobutane formed at 423 K over SO 3 2- /ZrO 2 (SZ) and Cs 2.5 H 0.5 PW 12 O 40 (Cs2.5) were close to binomial distributions, indicating that the isomerization proceeded mainly via a bimolecular mechanism on these catalysts. On the other hand, at 523 K over Cs2.5, the isotopic distribution pattern in isobutane was quite different from the binomial one; the fraction of 13 C 2 -isobutane was much greater than the binomial distribution. This result demonstrates that an intramolecular (monomolecular) rearrangement became significant at 523 K over Cs2.5. The contribution of monomolecular pathway was higher on Cs2.5 than on SZ. We presumed that the contribution of mechanism is related to the acidic property and the dehydrogenation ability of the catalyst. (S.Y.)

  12. Electrochemical mechanism of uranium mononitride dissolution in aqueous solutions of nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Ershov, Boris G. [Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Inst. of Physical Chemistry and Electrochemistry

    2017-09-01

    It was shown that the dissolution of UN with metallic conduction follows an electrochemical mechanism when it proceeds in contact with an electrically conductive medium (HNO{sub 3} solution). According to this mechanism, the oxidation of UN (at the anode) passes an electron into the UN matrix, which is a conductor, and can then reduce nitric acid in a parallel reaction a short distance away at another exposed surface of the UN (at the cathode). As a result, the reduction of HNO{sub 3} affords NO and NO{sub 2}, while oxidation of uranium mononitride affords NH{sub 3}, N{sub 2}, and N{sub 2}O. The occurrence of these two separate processes accounts for the composition and yields of the products formed from UN and HNO{sub 3} as well as for the nitrogen isotope distribution between them when UN and HNO{sub 3} were labeled with {sup 14} N or {sup 15}N. A mathematical equation describing the dependence of N{sub 2} and N{sub 2}O yields on HNO{sub 3} concentration was derived. It was also shown that the calculated value of standard electromotive force of the galvanic pair formed on the UN surface during its dissolution in HNO{sub 3} is high enough to initiate and support the electrochemical mechanism of its dissolution in nitric acid.

  13. Implication of Glutathione in the In Vitro Antiplasmodial Mechanism of Action of Ellagic Acid

    Science.gov (United States)

    Njomnang Soh, Patrice; Witkowski, Benoit; Gales, Amandine; Huyghe, Eric; Berry, Antoine

    2012-01-01

    The search for new antimalarial chemotherapy has become increasingly urgent due to parasite resistance to current drugs. Ellagic acid (EA) is a polyphenol, recently found in various plant products, that has effective antimalarial activity in vitro and in vivo without toxicity. To further understand the antimalarial mechanism of action of EA in vitro, we evaluated the effects of EA, ascorbic acid and N-acetyl-L-cysteine (NAC), alone and/or in combination on the production of reactive oxygen species (ROS) during the trophozoite and schizonte stages of the erythrocytic cycle of P. falciparum. The parasitized erythrocytes were pre-labelled with DCFDA (dichlorofluorescein diacetate). We showed that NAC had no effect on ROS production, contrary to ascorbic acid and EA, which considerably reduced ROS production. Surprisingly, EA reduced the production of the ROS with concentrations (6.6×10−9 − 6.6×10−6 M) ten-fold lower than ascorbic acid (113×10−6 M). Additionally, the in vitro drug sensitivity of EA with antioxidants showed that antiplasmodial activity is independent of the ROS production inside parasites, which was confirmed by the additive activity of EA and desferrioxamine. Finally, EA could act by reducing the glutathione content inside the Plasmodium parasite. This was consolidated by the decrease in the antiplasmodial efficacy of EA in the murine model Plasmodium yoelii- high GSH strain, known for its high glutathione content. Given its low toxicity and now known mechanism of action, EA appears as a promising antiplasmodial compound. PMID:23029306

  14. Mechanism for cyclization reaction by clavaminic acid synthase. Insights from modeling studies.

    Science.gov (United States)

    Borowski, Tomasz; de Marothy, Sven; Broclawik, Ewa; Schofield, Christopher J; Siegbahn, Per E M

    2007-03-27

    The mechanism of the oxidative cyclization reaction catalyzed by clavaminic acid synthase (CAS) was studied in silico. First, a classical molecular dynamics (MD) simulation was performed to obtain a realistic structure of the CAS-Fe(IV)=O-succinate-substrate complex; then potential of mean force (PMF) was calculated to assess the feasibility of the beta-lactam ring, more specifically its C4' corner, approaching the oxo atom. Based on the MD structure, a relatively large model of the active site region was selected and used in the B3LYP investigation of the reaction mechanism. The computational results suggest that once the oxoferryl species is formed, the oxidative cyclization catalyzed by CAS most likely involves either a mechanism involving C4'(S)-H bond cleavage of the monocyclic beta-lactam ring, or a biosynthetically unprecedented mechanism comprising (1) oxidation of the hydroxyl group of PCA to an O-radical, (2) retro-aldol-like decomposition of the O-radical to an aldehyde and a C-centered radical, which is stabilized by the captodative effect, (3) abstraction of a hydrogen atom from the C4'(S) position of the C-centered radical by the Fe(III)-OH species yielding an azomethine ylide, and (4) 1,3-dipolar cycloaddition to the ylide with aldehyde acting as a dipolarophile. Precedent for the new proposed mechanism comes from the reported synthesis of oxapenams via 1,3-dipolar cycloaddition reactions of aldehydes and ketones.

  15. Harnessing Neutrophil Survival Mechanisms during Chronic Infection by Pseudomonas aeruginosa: Novel Therapeutic Targets to Dampen Inflammation in Cystic Fibrosis

    Directory of Open Access Journals (Sweden)

    Benoît S. Marteyn

    2017-06-01

    Full Text Available More than two decades after cloning the cystic fibrosis transmembrane regulator (CFTR gene, the defective gene in cystic fibrosis (CF, we still do not understand how dysfunction of this ion channel causes lung disease and the tremendous neutrophil burden which persists within the airways; nor why chronic colonization by Pseudomonas aeruginosa develops in CF patients who are thought to be immunocompetent. It appears that the microenvironment within the lung of CF patients provides favorable conditions for both P. aeruginosa colonization and neutrophil survival. In this context, the ability of bacteria to induce hypoxia, which in turn affects neutrophil survival is an additional level of complexity that needs to be accounted for when controlling neutrophil fate in CF. Recent studies have underscored the importance of neutrophils in innate immunity and their functions appear to extend far beyond their well-described role in antibacterial defense. Perhaps a disturbance in neutrophil reprogramming during the course of an infection severely modulates the inflammatory response in CF. Furthermore there is an emerging concept that the CFTR itself may be an immune modulator and stimulating CFTR function in CF patients could promote neutrophil and macrophages antimicrobial function. Fostering the resolution of inflammation by favoring neutrophil apoptosis could preserve their microbicidal activities but decrease their proinflammatory potential. In this context, triggering neutrophil apoptosis with roscovitine may be a potential therapeutic option and this is currently being evaluated in CF patients. In the present review we discuss how neutrophils functions are disturbed in CF and how this may relate to chronic infection with P. aeuginosa and we propose novel research directions aimed at modulating neutrophil survival, dampening lung inflammation and ultimately leading to an amelioration of the lung disease.

  16. Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

    International Nuclear Information System (INIS)

    Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke

    2000-01-01

    The interaction of caffeic acid with e aq - , (CH 3 ) 2 (OH) CCH 2 · , CO 2 ·- , H · , ·OH and N 3 · radicals were studied by γ-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/·OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

  17. MECHANICAL PROPERTIES AND SULFURIC ACID RESISTANCE OF HIGH VOLUME CLASS C FLY ASH CONCRETE

    Directory of Open Access Journals (Sweden)

    Halit YAZICI

    2005-03-01

    Full Text Available In this study, some physical and mechanical properties of concrete mixtures containing high volume Class C fly ash have been investigated. Two different curing conditions, standard curing in water and curing in air were applied to the specimens in which 40 to 70 % cement was replaced with fly ash. Compressive strength, splitting tensile strength, modulus of elasticity and sulfuric acid resistance of concrete mixes, the volume stability of mortar bar specimens and setting times of pastes were investigated. Test results are presented comparatively with control specimens which have only Portland cement as a binder.

  18. Effects of primary dicarboxylic acids on microstructure and mechanical properties of sub-microcrystalline Ni-Co alloys

    International Nuclear Information System (INIS)

    Vijayakumar, J.; Mohan, S.; Yadav, S. Sunil

    2011-01-01

    Highlights: → The electrodeposited Ni-Co alloys are mostly used in magnetic sensors and it has good mechanical and corrosion resistance properties. → The effect of dicarboxylic acid leads to preferred (2 0 0) crystalline orientation, this may improve magnetic properties dicarboxylic acid can alter the elemental composition of Ni-Co alloy. → Dicarboxylic acid acts as a good brightner. - Abstract: Nickel-cobalt alloys were deposited from sulfate electrolyte with oxalic, malonic and succinic acids as additives and their microstructure and mechanical properties were studied. The crystal structure, surface morphologies, and chemical composition of coatings were investigated using X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy. The crystal structure and surface morphology analysis showed that the addition of dicarboxylic acid leads to (2 0 0) crystal face and the surface were more compact and uniform due to the grain refining. Ni 60 -Co 40 alloy was achieved when succinic acid is used as additive.

  19. Survival of Low-pH Stress by Escherichia coli O157:H7: Correlation between Alterations in the Cell Envelope and Increased Acid Tolerance

    Science.gov (United States)

    Jordan, Kieran N.; Oxford, Lynn; O’Byrne, Conor P.

    1999-01-01

    Survival of a nontoxigenic isolate of Escherichia coli O157:H7 at low pH (pH 3.0) was examined over prolonged time periods for each of three population types: exponential-phase cells, stationary-phase cells, and acid-adapted exponential-phase cells. In each population, approximately 5 × 104 CFU ml−1 were detected after a 24-h incubation at pH 3.0. Even after 3 days at pH 3.0, significant numbers of survivors from each of the three populations could be detected. The high level of acid tolerance exhibited by these survivors was found to be quickly lost once they were transferred to conditions which permitted growth to resume, indicating that they were not mutants. Proton flux measurements on the three populations of cells revealed that the initial rates of viability loss at pH 3.0 correlated well with net proton accumulation. Cells showing a high initial rate of viability loss (exponential-phase cells) accumulated protons at the highest rate, whereas resistant populations (adapted or stationary-phase cells) accumulated protons only slowly. Differences in the protein composition of the cell envelope between the three populations were studied by two-dimensional polyacrylamide gel electrophoresis. Complex differences in the pattern of proteins expressed by each population were uncovered. The implications of these findings are discussed in the context of a possible model accounting for acid tolerance in this important food-borne pathogen. PMID:10388702

  20. Nitrous acid (HONO) nocturnal surface deposition and daytime acid displacement: An alternative mechanism contributing to the unknown daytime HONO source

    Science.gov (United States)

    Murphy, J. G.; VandenBoer, T. C.; Roberts, J. M.; Young, C. J.; Brown, S. S.; Markovic, M. Z.; Talukdar, R. K.

    2012-12-01

    Measurements of HONO were made during two intensive field campaigns: NACHTT 2011 in Erie, CO and CalNex 2010 in Bakersfield, CA. These field data and results from a flow tube study provide a new perspective on the interactions of HONO with ground surfaces. Integrated atmospheric column measurements of HONO and NO2 during NACHTT provided clear evidence that the ground surface dominates HONO production and loss at night. Simultaneous measurements of the gas and particle phases made by an Ambient Ion Monitor - Ion Chromatography (AIM-IC) system during CalNex demonstrated the potential for reactive uptake of HONO on mineral dust/soil as a nocturnal sink. Similarly, the potential for nitrite salts to react with strong acids, displacing HONO during the day was suggested by this dataset. Lab study results confirmed that HONO reacts irreversibly with carbonate salts and real soil extracts. Relative humidity-dependent reactive uptake coefficients were derived. Subsequent release of HONO by displacement reactions with HNO3 and HCl was also demonstrated. Together, these field and lab studies contribute to a new picture of HONO surface interactions by providing i) a more explicit description of the nocturnal HONO sink that also is a surface reservoir and ii) a new mechanism for daytime HONO formation that does not require NO2.

  1. An influence of mechanical activation on the selectivity of tetrahedrite acid leaching

    Directory of Open Access Journals (Sweden)

    Jaroslav Briančin

    2005-11-01

    Full Text Available Sulphidic mineral - tetrahedrite Cu12Sb4S13 was subjected to leaching in a H2SO4 medium. Physico-chemical changes of a mechanically activated mineral were investigated before and after leaching using the infrared spectroscopy and the scanning electron microscopy. The mechanical activation of the mineral resulted in the mechanochemical surface oxidation and the formation of sulphates and iron carbonate. Further, the specific surface area and the crystal structure disordering of the mineral increased. These aspects influence the kinetics and the selectivity of acid leaching of tetrahedrite. The effect of the reaction surface decreases due to the agglomeration during the milling and the formation of iron hydroxyoxides or iron hydroxysulphates from admixed pyrite and adversely affects the extraction rate of metals from tetrahedrite.

  2. The crystal morphology and mechanical properties based on poly(l-lactic acid)/silica nanocomposites

    Science.gov (United States)

    Cai, Y. H.

    2017-06-01

    Nano silica (SiO2) was introduced into Poly(L-lactic acid) (PLLA) matrix to prepare PLLA/SiO2 nanocomposites, and the crystal morphology, crystallization behavior and mechanical performance were investigated. The XRD experimental data indicated that nano SiO2 could improve the crystallization of PLLA, and PLLA/SiO2 nanocomposites exhibited sharp diffraction peak after isothermal crystallization. In addition, through the POM analysis, PLLA/SiO2 sample had the typical spherulite structure, and the size of the spherulite became larger with the increase of crystallization temperature. The tensile testing showed that a small amount of SiO2 could improve and retain the mechanical performance of PLLA

  3. Sub-optimal pH Preadaptation Improves the Survival of Lactobacillus plantarum Strains and the Malic Acid Consumption in Wine-Like Medium.

    Science.gov (United States)

    Succi, Mariantonietta; Pannella, Gianfranco; Tremonte, Patrizio; Tipaldi, Luca; Coppola, Raffaele; Iorizzo, Massimo; Lombardi, Silvia Jane; Sorrentino, Elena

    2017-01-01

    Forty-two oenological strains of Lb. plantarum were assessed for their response to ethanol and pH values generally encountered in wines. Strains showed a higher variability in the survival when exposed to low pH (3.5 or 3.0) than when exposed to ethanol (10 or 14%). The study allowed to individuate the highest ethanol concentration (8%) and the lowest pH value (4.0) for the growth of strains, even if the maximum specific growth rate (μ max ) resulted significantly reduced by these conditions. Two strains (GT1 and LT11) preadapted to 2% ethanol and cultured up to 14% of ethanol showed a higher growth than those non-preadapted when they were cultivated at 8% of ethanol. The evaluation of the same strains preadapted to low pH values (5.0 and 4.0) and then grown at pH 3.5 or 3.0 showed only for GT1 a sensitive μ max increment when it was cultivated in MRS at pH 3 after a preadaptation to pH 5.0. The survival of GT1 and LT11 was evaluated in Ringer's solution at 14% ethanol after a long-term adaptation in MRS with 2% ethanol or in MRS with 2% ethanol acidified at pH 5.0 (both conditions, BC). Analogously, the survival was evaluated at pH 3.5 after a long-term adaptation in MRS at pH 5.0 or in MRS BC. The impact of the physiologic state (exponential phase vs stationary phase) on the survival was also evaluated. Preadapted cells showed the same behavior of non-preadapted cells only when cultures were recovered in the stationary phase. Mathematical functions were individuated for the description of the survival of GT1 and LT11 in MRS at 14% ethanol or at pH 3.5. Finally, a synthetic wine (SW) was used to assess the behavior of Lb. plantarum GT1 and LT11 preadapted in MRS at 2% ethanol or at pH 5.0 or in BC. Only GT1 preadapted to pH 5.0 and collected in the stationary phase showed constant values of microbial counts after incubation for 15 days at 20°C. In addition, after 15 days the L-malic acid resulted completely degraded and the pH value increased of about 0.3 units.

  4. Polyunsaturated fatty acids and type 2 diabetes: Impact on the glycemic control mechanism.

    Science.gov (United States)

    Coelho, Olívia Gonçalves Leão; da Silva, Bárbara Pereira; Rocha, Daniela Mayumi Usuda Prado; Lopes, Lílian Lelis; Alfenas, Rita de Cássia Gonçalves

    2017-11-22

    There is a growing mortality related to co-morbidities associated with diabetes mellitus. Intake of polyunsaturated fatty acids (PUFA) has been associated with low cardiometabolic risk and reduction of inflammatory process. The objective of this paper is to review the impact of PUFA intake on glycemic control in diabetic patients as well as to elucidate the possible mechanisms involved. Medline/PubMed electronic database was searched to identify studies published within last five years regarding the effect of PUFA intake on glucose metabolism in type 2 diabetics. The search terms used were "polyunsaturated fatty acid(s)," "PUFA," and "diabetes." We included only interventional studies that assessed the effects of PUFA intake on glucose metabolism - fasting glucose, serum insulin, HbA1c, and HOMA-IR assessment- in type 2 diabetics. Initially, 48 articles were identified, of which one was not available and 41 did not match the inclusion criteria. Within the selected studies, three articles showed an improvement in fasting blood glucose, two showed an increase in fasting glycemia, and there was no effect of intervention in one article only. Based on the analyzed clinical interventional studies, supplementation of 0.42-5.2-g PUFA/day for at least eight weeks may become an alternative treatment for type 2 diabetes mellitus, particularly in Asian subjects.

  5. Mechanical behavior of alumina and alumina-feldspar based ceramics in an acetic acid (4%) environment

    International Nuclear Information System (INIS)

    Stumpf, Aisha S.G.; Bergmann, Carlos P.; Vicenzi, Juliane; Fetter, Rebecca; Mundstock, Karina S.

    2009-01-01

    This study investigates the mechanical properties of alumina-feldspar based ceramics when exposed to an aggressive environment (acetic acid 4%). Alumina ceramics containing different concentrations of feldspar (0%, 1%, 5%, 10%, or 40%) were sintered at either 1300, 1600, or 1700 o C. Flaws (of width 0%, 30%, or 50%) were introduced into the specimens using a saw. Half of these ceramic bodies were exposed to acetic acid. Their flexural strength, K IC , and porosity were measured and the fractured samples were evaluated using scanning electronic- and optical microscopy. It was found that in the ceramic bodies sintered at 1600 o C, feldspar content up to 10% improved flexural strength and K IC, and reduced porosities. Generally, it was found that acetic acid had a weakening effect on the flexural strength of samples sintered at 1700 o C but a beneficial effect on K IC of ceramics sintered at 1600 o C. It was concluded that alumina-based ceramics with feldspar content up to 10% and sintered at higher temperatures would perform better in an aggressive environment similar to oral cavity.

  6. Fibrous hyaluronic acid hydrogels that direct MSC chondrogenesis through mechanical and adhesive cues.

    Science.gov (United States)

    Kim, Iris L; Khetan, Sudhir; Baker, Brendon M; Chen, Christopher S; Burdick, Jason A

    2013-07-01

    Electrospinning has recently gained much interest due to its ability to form scaffolds that mimic the nanofibrous nature of the extracellular matrix, such as the size and depth-dependent alignment of collagen fibers within hyaline cartilage. While much progress has been made in developing bulk, isotropic hydrogels for tissue engineering and understanding how the microenvironment of such scaffolds affects cell response, these effects have not been extensively studied in a nanofibrous system. Here, we show that the mechanics (through intrafiber crosslink density) and adhesivity (through RGD density) of electrospun hyaluronic acid (HA) fibers significantly affect human mesenchymal stem cell (hMSC) interactions and gene expression. Specifically, hMSC spreading, proliferation, and focal adhesion formation were dependent on RGD density, but not on the range of fiber mechanics investigated. Moreover, traction-mediated fiber displacements generally increased with more adhesive fibers. The expression of chondrogenic markers, unlike trends in cell spreading and cytoskeletal organization, was influenced by both fiber mechanics and adhesivity, in which softer fibers and lower RGD densities generally enhanced chondrogenesis. This work not only reveals concurrent effects of mechanics and adhesivity in a fibrous context, but also highlights fibrous HA hydrogels as a promising scaffold for future cartilage repair strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Xingxun Liu

    2014-01-01

    Full Text Available Addition of filler to polylactic acid (PLA may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC, scanning electron microscope (SEM, instron tensile tester, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, and dynamic mechanical analysis (DMA. It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

  8. Quinolinic Acid, an endogenous molecule combining excitotoxicity, oxidative stress and other toxic mechanisms.

    Science.gov (United States)

    Pérez-De La Cruz, Verónica; Carrillo-Mora, Paul; Santamaría, Abel

    2012-01-01

    Quinolinic acid (QUIN), an endogenous metabolite of the kynurenine pathway, is involved in several neurological disorders, including Huntington's disease, Alzheimer's disease, schizophrenia, HIV associated dementia (HAD) etc. QUIN toxicity involves several mechanisms which trigger various metabolic pathways and transcription factors. The primary mechanism exerted by this excitotoxin in the central nervous system (CNS) has been largely related with the overactivation of N-methyl-D-aspartate receptors and increased cytosolic Ca(2+) concentrations, followed by mitochondrial dysfunction, cytochrome c release, ATP exhaustion, free radical formation and oxidative damage. As a result, this toxic pattern is responsible for selective loss of middle size striatal spiny GABAergic neurons and motor alterations in lesioned animals. This toxin has recently gained attention in biomedical research as, in addition to its proven excitotoxic profile, a considerable amount of evidence suggests that oxidative stress and energetic disturbances are major constituents of its toxic pattern in the CNS. Hence, this profile has changed our perception of how QUIN-related disorders combine different toxic mechanisms resulting in brain damage. This review will focus on the description and integration of recent evidence supporting old and suggesting new mechanisms to explain QUIN toxicity.

  9. Quinolinic Acid, an Endogenous Molecule Combining Excitotoxicity, Oxidative Stress and Other Toxic Mechanisms

    Directory of Open Access Journals (Sweden)

    Verónica Pérez-De La Cruz

    2012-01-01

    Full Text Available Quinolinic acid (QUIN, an endogenous metabolite of the kynurenine pathway, is involved in several neurological disorders, including Huntington's disease, Alzheimer's disease, schizophrenia, HIV associated dementia (HAD etc. QUIN toxicity involves several mechanisms which trigger various metabolic pathways and transcription factors. The primary mechanism exerted by this excitotoxin in the central nervous system (CNS has been largely related with the overactivation of N-methyl-D-aspartate receptors and increased cytosolic Ca 2+ concentrations, followed by mitochondrial dysfunction, cytochrome c release, ATP exhaustion, free radical formation and oxidative damage. As a result, this toxic pattern is responsible for selective loss of middle size striatal spiny GABAergic neurons and motor alterations in lesioned animals. This toxin has recently gained attention in biomedical research as, in addition to its proven excitotoxic profile, a considerable amount of evidence suggests that oxidative stress and energetic disturbances are major constituents of its toxic pattern in the CNS. Hence, this profile has changed our perception of how QUIN-related disorders combine different toxic mechanisms resulting in brain damage. This review will focus on the description and integration of recent evidence supporting old and suggesting new mechanisms to explain QUIN toxicity.

  10. Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid).

    Science.gov (United States)

    Liu, Xingxun; Wang, Tongxin; Chow, Laurence C; Yang, Mingshu; Mitchell, James W

    Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC), scanning electron microscope (SEM), instron tensile tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

  11. Mechanisms of the rapid dissolution of plutonium dioxide in acidic media under oxidizing or reducing conditions

    International Nuclear Information System (INIS)

    Madic, C.; Berger, P.; Machuron-Mandard, X.

    1990-01-01

    Until recently plutonium dioxide was known to be among the metallic oxides most difficult to dissolve. This property is understandable given the free energy of the dissolution reaction (ΔG 0 ) in acidic noncomplexing media (ΔG 0 = 32.04 kJ/mol). Thermodynamic calculations predict that PuO 2 will dissolve under oxidizing or reducing conditions. The oxidizing dissolution, leading to Pu(VI) ion in solution, is easy to perform with a strong oxidant like Ag(II). The mechanism of the oxidizing dissolution of PuO 2 was investigated by using carbon paste electrochemistry (CPE) and 18 O labeling. PuO 2 can also be dissolved in acidic solution if the redox potential of the mixture is low (e.g., Cr 2+ , V 2+ , or U 3+ as reducing agents). The kinetics of the heterogeneous reducing dissolution of PuO 2 with Cr 2+ were investigated and the reaction mechanism was determined by 18 O labeling. All the results will be presented and discussed in the context of minimizing the amount of plutonium-contaminated solid wastes in the nuclear fuel cycle. 9 figs., 17 refs

  12. All guns blazing: management and survival of massive valproic acid overdose – case report and literature review

    Directory of Open Access Journals (Sweden)

    Al Jawder S

    2018-01-01

    Full Text Available Shaikha Al Jawder,1 Eiman AlJishi,2 Shaikhah Al-Otaibi,2 Mohammed S Al-Shahrani3 1King Hamad University Hospital, Busaiteen, Bahrain; 2Emergency Medicine Department, 3Emergency and Critical Care Department, King Fahad Hospital of the University, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia Abstract: A 51-year-old woman, who intentionally ingested a massive dose of ~60 g of valproic acid which she was using as a mood stabilizer for bipolar affective disorder, presented within 30 minutes of ingestion to the emergency department. The patient was asymptomatic and was immediately started on decontamination therapy with activated charcoal (AC. Drug serum levels, liver functions, and ammonia levels were tested and followed up during treatment. Due to the massive ingestion and continuous rise in serum drug levels, the patient received regular multiple doses of AC, as well as l-carnitine for liver protection. The patient was started on extracorporeal therapy in the form of renal replacement therapy in the intensive care unit (ICU, followed by intermittent hemodialysis. Drug serum levels dropped significantly. Ammonia levels showed improvement with treatment. The patient was discharged from the ICU after 14 days of treatment. She was stable and in good condition with no residual hepatic or central nervous system (CNS manifestations. Keywords: valproic acid, multiple dose activated charcoal, l-carnitine, hemodialysis

  13. Kinetic mechanism and structural requirements of the amine-catalyzed decarboxylation of oxaloacetic acid.

    Science.gov (United States)

    Thalji, Nabil K; Crowe, William E; Waldrop, Grover L

    2009-01-02

    The kinetic and chemical mechanism of amine-catalyzed decarboxylation of oxaloacetic acid at pH 8.0 has been reevaluated using a new and versatile assay. Amine-catalyzed decarboxylation of oxaloacetic acid proceeds via the formation of an imine intermediate, followed by decarboxylation of the intermediate and hydrolysis to yield pyruvate. The decrease in oxaloacetic acid was coupled to NADH formation by malate dehydrogenase, which allowed the rates of both initial carbinolamine formation (as part of the imination step) and decarboxylation to be determined. By comparing the rates observed for a variety of amines and, in particular, diamines, the structural and electronic requirements for diamine-catalyzed decarboxylation at pH 8.0 were identified. At pH 8.0, monoamines were found to be very poor catalysts, whereas some diamines, most notably ethylenediamine, were excellent catalysts. The results indicate that the second amino group of diamines enhances the rate of imine formation by acting as a proton shuttle during the carbinolamine formation step, which enables diamines to overcome high levels of solvation that would otherwise inhibit carbinolamine, and thus imine, formation. The presence of the second amino group may also enhance the rate of the carbinolamine dehydration step. In contrast to the findings of previous reports, the second amino group participates in the reaction by enhancing the rate of decarboxylation via hydrogen-bonding to the imine nitrogen to either stabilize the negative charge that develops on the imine during decarboxylation or preferentially stabilize the reactive imine over the unreactive enamine tautomer. These results provide insight into the precise catalytic mechanism of several enzymes whose reactions are known to proceed via an imine intermediate.

  14. A new leptin-mediated mechanism for stimulating fatty acid oxidation: a pivotal role for sarcolemmal FAT/CD36.

    Science.gov (United States)

    Momken, Iman; Chabowski, Adrian; Dirkx, Ellen; Nabben, Miranda; Jain, Swati S; McFarlan, Jay T; Glatz, Jan F C; Luiken, Joost J F P; Bonen, Arend

    2017-01-01

    Leptin stimulates fatty acid oxidation in muscle and heart; but, the mechanism by which these tissues provide additional intracellular fatty acids for their oxidation remains unknown. We examined, in isolated muscle and cardiac myocytes, whether leptin, via AMP-activated protein kinase (AMPK) activation, stimulated fatty acid translocase (FAT/CD36)-mediated fatty acid uptake to enhance fatty acid oxidation. In both mouse skeletal muscle and rat cardiomyocytes, leptin increased fatty acid oxidation, an effect that was blocked when AMPK phosphorylation was inhibited by adenine 9-β-d-arabinofuranoside or Compound C. In wild-type mice, leptin induced the translocation of FAT/CD36 to the plasma membrane and increased fatty acid uptake into giant sarcolemmal vesicles and into cardiomyocytes. In muscles of FAT/CD36-KO mice, and in cardiomyocytes in which cell surface FAT/CD36 action was blocked by sulfo-N-succinimidyl oleate, the leptin-stimulated influx of fatty acids was inhibited; concomitantly, the normal leptin-stimulated increase in fatty acid oxidation was also prevented, despite the normal leptin-induced increase in AMPK phosphorylation. Conversely, in muscle of AMPK kinase-dead mice, leptin failed to induce the translocation of FAT/CD36, along with a failure to stimulate fatty acid uptake and oxidation. Similarly, when siRNA was used to reduce AMPK in HL-1 cardiomyocytes, leptin failed to induce the translocation of FAT/CD36. Our studies have revealed a novel mechanism of leptin-induced fatty acid oxidation in muscle tissue; namely, this process is dependent on the activation of AMPK to induce the translocation of FAT/CD36 to the plasma membrane, thereby stimulating fatty acid uptake. Without increasing this leptin-stimulated, FAT/CD36-dependent fatty acid uptake process, leptin-stimulated AMPK phosphorylation does not enhance fatty acid oxidation. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  15. Docosahexaenoic acid signaling modulates cell survival in experimental ischemic stroke penumbra and initiates long-term repair in young and aged rats.

    Directory of Open Access Journals (Sweden)

    Tiffany N Eady

    Full Text Available Docosahexaenoic acid, a major omega-3 essential fatty acid family member, improves behavioral deficit and reduces infarct volume and edema after experimental focal cerebral ischemia. We hypothesize that DHA elicits neuroprotection by inducing AKT/p70S6K phosphorylation, which in turn leads to cell survival and protects against ischemic stroke in young and aged rats.Rats underwent 2 h of middle cerebral artery occlusion (MCAo. DHA, neuroprotectin D1 (NPD1 or vehicle (saline was administered 3 h after onset of stroke. Neurological function was evaluated on days 1, 2, 3, and 7. DHA treatment improved functional recovery and reduced cortical, subcortical and total infarct volumes 7 days after stroke. DHA also reduced microglia infiltration and increased the number of astrocytes and neurons when compared to vehicle on days 1 and 7. Increases in p473 AKT and p308 AKT phosphorylation/activation were observed in animals treated with DHA 4 h after MCAo. Activation of other members of the AKT signaling pathway were also observed in DHA treated animals including increases in pS6 at 4 h and pGSK at 24 h. DHA or NPD1 remarkably reduced total and cortical infarct in aged rats. Moreover, we show that in young and aged rats DHA treatment after MCAo potentiates NPD1 biosynthesis. The phosphorylation of p308 AKT or pGSK was not different between groups in aged rats. However, pS6 expression was increased with DHA or NPD1 treatment when compared to vehicle.We suggest that DHA induces cell survival, modulates the neuroinflammatory response and triggers long term restoration of synaptic circuits. Both DHA and NPD1 elicited remarkable protection in aged animals. Accordingly, activation of DHA signaling might provide benefits in the management of ischemic stroke both acutely as well as long term to limit ensuing disabilities.

  16. Attachment of Escherichia coli O157:H7 in ground beef to meat grinders and survival after sanitation with chlorine and peroxyacetic acid.

    Science.gov (United States)

    Farrell, B L; Ronner, A B; Wong, A C

    1998-07-01

    The potential for transfer of Escherichia coli O157:H7 from contaminated ground beef to grinding equipment and the inactivation of attached cells during cleaning and sanitizing was examined. Chub-packed ground beef with lean:fat ratios of 75:25, 80:20 or 90:10 was inoculated with 6 log CFU/g or 2 log CFU/g E. coli O157:H7 strain FRIK 910. Samples were consecutively ground in a Hobart meat grinder with stainless steel (SS) chips (1 cm2) glued to the auger housing. Chips were harvested after grinding, detergent washing with or without manual scrubbing and rinsing, sanitizing in a chlorine or peroxyacetic acid sanitizer, and overnight storage. Survival of E. coli O157:H7 was evaluated both by plate count and enrichment in trypticase soy broth. Approximately 3 to 4 log CFU/cm2 were attached to the SS after grinding with all three fat contents. After washing and sanitizing in a chlorine or peroxyacetic acid sanitizer, viable bacteria were infrequently recovered by plate count. Enrichment of chips resulted in a higher survival rate with both sanitizing treatments, indicating that cell numbers below the limit of detection (5 CFU/cm2) or potentially injured organisms remained on the surface. Manual scrubbing during the washing step reduced the recovery rate. The scrubbing step also increased the number of passing scores assigned using an ATP bioluminescence assay of total residual soil on the chips sanitized in chlorine. The overall results indicate that plate counts alone may not be a reliable indicator of sanitation efficacy and may be validated by enrichment assay.

  17. Examination of 12-lipoxygenase (12-LOX) as a therapeutic target in non-small cell lung cancer (NSCLC): Mechanisms controlling survival and induction of apoptosis following selective inhibition

    LENUS (Irish Health Repository)

    Cathcart, Mary Clare

    2011-06-01

    Background: Platelet-type 12-LOX is an arachidonic acid metabolising enzyme resulting in the formation of 12(S)-HETE, which stimulates tumour cell adhesion, invasion and metastasis. This study aimed to examine the expression profile and role of this enzyme in NSCLC, and determine if it is a potential target for intervention. Methods: A panel of retrospective resected lung tumours was stained for 12-LOX expression by IHC. Levels of the 12-LOX metabolite, 12(S)-HETE, were examined in 50 NSCLC serum samples, and correlated with serum VEGF. A panel of NSCLC cell lines were treated with baicalein (10 uM), a selective inhibitor of 12-LOX, or 12(S)-HETE (100 ng\\/ml) and cell survival\\/proliferation examined by BrdU. Apoptosis following 12-LOX inhibition was examined by HCS and validated by FACS and DNA laddering. The effect of 12-LOX inhibition on NSCLC tumour growth and survival was examined in-vivo using an athymic nude mouse model. Gene alterations following 12-LOX inhibition in NSCLC cell lines were assessed by qPCR arrays and validated by RT-PCR. Transient transfection methods were used to examine the effects of 12-LOX overexpression in NSCLC cells. Results: 12-LOX expression was observed to a varying degree in human lung cancers of varying histological subtypes. 12(S)-HETE levels were correlated (p<0.05) with those of VEGF. Baicalein inhibited proliferation\\/survival in all cell lines, while 12(S)-HETE increased proliferation. 12-LOX inhibition increased apoptosis, indicated by a reduction in f-actin content and mitochondrial mass potential. Treatment with baicalein significantly reduced the growth of NSCLC tumours and increased overall survival in athymic nude mice. qPCR array data implicated a number of apoptosis\\/angiogenesis genes regulating these effects, including bcl-2, VEGF, integrin A2 and A4. 12-LOX overexpression resulted in an increase in VEGF secretion, confirming qPCR observations. Conclusions: 12-LOX is a survival factor\\/potential target in

  18. Corrosion mechanism of Z3 CN18.10 stainless steel in the presence of nitric acid condensates

    International Nuclear Information System (INIS)

    Balbaud, Fanny

    1998-01-01

    In installations handling concentrated boiling nitric acid, a severe intergranular corrosion can sometimes occur in condensation zones constituted of non-sensitized Z3 CN 18.10 stainless steel. Corrosion tests in reactors and in a specific loop, CIRCE, allowed to specify the conditions of occurrence of this type of corrosion and showed the similitude with the corrosion in non-renewed liquid nitric acid: the specific parameters linked to the condensate phase are the high ratio metallic surface area to volume of condensate and the low renewing rate which induce a concentration of oxidation products of the metal and of reduction products of nitric acid. The initiation of the intergranular corrosion is attributed to the increase in the reduction rate of nitric acid by an autocatalytic mechanism which was demonstrated by electrochemical measurements on platinum and on stainless steel. The reduction mechanism involves a charge transfer step where nitrous acid, the electro-active species, is reduced into nitrogen monoxide and a chemical regeneration reaction of nitrous acid. The thermodynamic study led to a representation of the chemical and electrochemical properties of nitric acid. This study allowed also to determine the Gibbs free energy of formation of nitrous acid in solution in concentrated nitric acid at 100 deg. C. The diagram, constructed in coordinates log(P O 2 ) / [-log(P HNO 3 )] or E eXperimental / [-log(P HNO 3 )], shows that the final reduction product of nitric acid depends on the concentration of nitric acid: at 100 deg. C, NO is obtained for concentrations lower than 8 mol.L -1 and NO 2 is obtained for higher concentrations. All these results allowed to propose a corrosion mechanism of Z3 CN 18.10 stainless steel in the presence of nitric acid condensates. [fr

  19. Metabolic effects of free fatty acids during endotoxaemia in a porcine model--free fatty acid inhibition of growth hormone secretion as a potential catabolic feedback mechanism.

    Science.gov (United States)

    Buhl, M; Gjedsted, J; Granfeldt, A; Larsen, P Ø; Schmitz, O; Tønnesen, E; Møller, N

    2010-05-01

    Critical illness and severe inflammation are catabolic states characterised by breakdown of tissue and protein stores, by increased levels of free fatty acids, and by insulin resistance. These metabolic features contribute to morbidity and mortality. Growth hormone and insulin are the two major anabolic hormones. The present study was designed to test whether increased levels of free fatty acids (i) inhibit growth hormone secretion and (ii) induce insulin resistance during acute endotoxin exposure in a porcine model of critical illness. We studied 20 pigs for 6 h during combined anaesthesia and endotoxin infusion and a hyperinsulinaemic glucose clamp to control glucose, insulin, and free fatty acid concentrations. Pigs were randomised to two different continuous infusion rates of Intralipid resulting in different, sustained, and elevated free fatty acid concentrations (1.63 mmol l(-1) vs. 0.58 mmol l(-1), p=0.0002). Concomitantly, we observed reduced growth hormone concentrations in the group with high free fatty acid concentrations (3.5 ng ml(-1) vs. 6.6 ng ml(-1), pfeedback mechanism whereby growth hormone induced-stimulation of free fatty acids release inhibit growth hormone secretion. This mechanism may further contribute to protein loss in critical illness. We found no evidence that the increment of plasma free fatty acids between groups contribute to insulin resistance in critical illness. Georg Thieme Verlag KG Stuttgart-New York.

  20. Effect of urine pH changed by dietary intervention on uric acid clearance mechanism of pH-dependent excretion of urinary uric acid

    Science.gov (United States)

    2012-01-01

    Background The finding reported in a previous paper - alkalization of urine facilitates uric acid excretion - is contradictory to what one might expect to occur: because food materials for the alkalization of urine contain fewer purine bodies than those for acidification, less uric acid in alkaline urine should have been excreted than in acid urine. To make clear what component of uric acid excretion mechanisms is responsible for this unexpected finding, we simultaneously collected data for the concentration of both creatinine and uric acid in serum as well as in urine, in order to calculate both uric acid and creatinine clearances. Methods Within the framework of the Japanese government’s health promotion program, we made recipes which consisted of protein-rich and less vegetable-fruit food materials for H + -load (acidic diet) and others composed of less protein and more vegetable-fruit rich food materials (alkaline diet). This is a crossover study within some limitations. Healthy female students, who had no medical problems at the regular physical examination provided by the university, were enrolled in this consecutive 5-day study for each test. From whole-day collected urine, total volume, pH, organic acid, creatinine, uric acid, titratable acid and all cations (Na+,K+,Ca2+,Mg2+,NH4+) and anions (Cl−,SO42−,PO4−) necessary for the estimation of acid–base balance were measured. In the early morning before breakfast of the 1st, 3rd and 5th experimental day, we sampled 5 mL of blood to estimate the creatinine and uric acid concentration in serum. Results and discussion Urine pH reached a steady state 3 days after switching from ordinary daily diets to specified regimens. The amount of acid generated ([SO42−] + organic acid − gut alkali)was linearly related with the excretion of acid (titratable acid + [NH4+] − [HCO3−]), indicating that H + in urine is generated by the metabolic degradation of food materials. Uric acid

  1. Effect of urine pH changed by dietary intervention on uric acid clearance mechanism of pH-dependent excretion of urinary uric acid

    Directory of Open Access Journals (Sweden)

    Kanbara Aya

    2012-06-01

    Full Text Available Abstract Background The finding reported in a previous paper - alkalization of urine facilitates uric acid excretion - is contradictory to what one might expect to occur: because food materials for the alkalization of urine contain fewer purine bodies than those for acidification, less uric acid in alkaline urine should have been excreted than in acid urine. To make clear what component of uric acid excretion mechanisms is responsible for this unexpected finding, we simultaneously collected data for the concentration of both creatinine and uric acid in serum as well as in urine, in order to calculate both uric acid and creatinine clearances. Methods Within the framework of the Japanese government’s health promotion program, we made recipes which consisted of protein-rich and less vegetable-fruit food materials for H + -load (acidic diet and others composed of less protein and more vegetable-fruit rich food materials (alkaline diet. This is a crossover study within some limitations. Healthy female students, who had no medical problems at the regular physical examination provided by the university, were enrolled in this consecutive 5-day study for each test. From whole-day collected urine, total volume, pH, organic acid, creatinine, uric acid, titratable acid and all cations (Na+,K+,Ca2+,Mg2+,NH4+ and anions (Cl−,SO42−,PO4− necessary for the estimation of acid–base balance were measured. In the early morning before breakfast of the 1st, 3rd and 5th experimental day, we sampled 5 mL of blood to estimate the creatinine and uric acid concentration in serum. Results and discussion Urine pH reached a steady state 3 days after switching from ordinary daily diets to specified regimens. The amount of acid generated ([SO42−] + organic acid − gut alkaliwas linearly related with the excretion of acid (titratable acid + [NH4+] − [HCO3−], indicating that H + in urine is generated by the metabolic degradation of

  2. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics

    Science.gov (United States)

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-12-01

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

  3. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics.

    Science.gov (United States)

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-12-22

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

  4. New insights into the mechanisms of acetic acid resistance in Acetobacter pasteurianus using iTRAQ-dependent quantitative proteomic analysis.

    Science.gov (United States)

    Xia, Kai; Zang, Ning; Zhang, Junmei; Zhang, Hong; Li, Yudong; Liu, Ye; Feng, Wei; Liang, Xinle

    2016-12-05

    Acetobacter pasteurianus is the main starter in rice vinegar manufacturing due to its remarkable abilities to resist and produce acetic acid. Although several mechanisms of acetic acid resistance have been proposed and only a few effector proteins have been identified, a comprehensive depiction of the biological processes involved in acetic acid resistance is needed. In this study, iTRAQ-based quantitative proteomic analysis was adopted to investigate the whole proteome of different acidic titers (3.6, 7.1 and 9.3%, w/v) of Acetobacter pasteurianus Ab3 during the vinegar fermentation process. Consequently, 1386 proteins, including 318 differentially expressed proteins (pacetic acid stress, where >150 proteins were differentially expressed. Specifically, proteins involved in amino acid metabolic processes and fatty acid biosynthesis were differentially expressed, which may contribute to the acetic acid resistance of Acetobacter. Transcription factors, two component systems and toxin-antitoxin systems were implicated in the modulatory network at multiple levels. In addition, the identification of proteins involved in redox homeostasis, protein metabolism, and the cell envelope suggested that the whole cellular system is mobilized in response to acid stress. These findings provide a differential proteomic profile of acetic acid resistance in Acetobacter pasteurianus and have potential application to highly acidic rice vinegar manufacturing. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Impact of citric acid and calcium ions on acid solubilization of mechanically separated turkey meat: effect on lipid and pigment content.

    Science.gov (United States)

    Hrynets, Y; Omana, D A; Xu, Y; Betti, M

    2011-02-01

    Increased demand for poultry products has resulted in an increased availability of by-products, such as the neck, back, and frame, that can be processed into mechanically separated poultry meat. The major problems with mechanically separated poultry meat are its high lipid content, color instability, and high susceptibility to lipid oxidation. The present work was undertaken to determine the effect of different concentrations of citric acid and calcium ions on protein yield, color characteristics, and lipid removal from protein isolates prepared using an acid-aided extraction process. Six levels of citric acid (0, 2, 4, 6, 8, and 10 mmol/L) and 2 levels of calcium chloride (0 and 8 mmol/L) were examined. The entire experiment was replicated 3 times, resulting in 36 extractions (3 × 6 × 2). The highest (P turkey meat, ranging from 86.2 to 94.7%. The lowest amount (1.14%) of total lipids obtained was for samples treated with 4 mmol/L of citric acid. Maximum removal of neutral lipids (96.5%) and polar lipids (96.4%) was attained with the addition of 6 and 2 mmol/L of citric acid, respectively. Polar lipid content was found to be significantly (P = 0.0045) affected by the presence of calcium chloride. The isolated proteins were less (P turkey meat. The most efficient removal of total heme pigment was obtained with the addition of 6 or 8 mmol/L of citric acid. Addition of calcium chloride had a negative effect on total pigment content. The study revealed that acid extractions with the addition of citric acid resulted in substantial removal of lipids and pigments from mechanically separated turkey meat, improved stability of the recovered proteins against lipid oxidation, and appreciable protein recovery yields.

  6. Palladium-atom catalyzed formic acid decomposition and the switch of reaction mechanism with temperature.

    Science.gov (United States)

    He, Nan; Li, Zhen Hua

    2016-04-21

    Formic acid decomposition (FAD) reaction has been an innovative way for hydrogen energy. Noble metal catalysts, especially palladium-containing nanoparticles, supported or unsupported, perform well in this reaction. Herein, we considered the simplest model, wherein one Pd atom is used as the FAD catalyst. With high-level theoretical calculations of CCSD(T)/CBS quality, we investigated all possible FAD pathways. The results show that FAD catalyzed by one Pd atom follows a different mechanism compared with that catalyzed by surfaces or larger clusters. At the initial stage of the reaction, FAD follows a dehydration route and is quickly poisoned by CO due to the formation of very stable PdCO. PdCO then becomes the actual catalyst for FAD at temperatures approximately below 1050 K. Beyond 1050 K, there is a switch of catalyst from PdCO to Pd atom. The results also show that dehydration is always favoured over dehydrogenation on either the Pd-atom or PdCO catalyst. On the Pd-atom catalyst, neither dehydrogenation nor dehydration follows the formate mechanism. In contrast, on the PdCO catalyst, dehydrogenation follows the formate mechanism, whereas dehydration does not. We also systematically investigated the performance of 24 density functional theory methods. We found that the performance of the double hybrid mPW2PLYP functional is the best, followed by the B3LYP, B3PW91, N12SX, M11, and B2PLYP functionals.

  7. Survival of brown trout during spring flood in DOC-rich streams in northern Sweden: the effect of present acid deposition and modelled pre-industrial water quality.

    Science.gov (United States)

    Laudon, Hjalmar; Poléo, Antonio B S; Vøllestad, Leif Asbjørn; Bishop, Kevin

    2005-05-01

    Mortality and physiological responses in brown trout (Salmo trutta) were studied during spring snow melt in six streams in northern Sweden that differed in concentrations of dissolved organic carbon (DOC) and pH declines. Data from these streams were used to create an empirical model for predicting fish responses (mortality and physiological disturbances) in DOC-rich streams using readily accessible water chemistry parameters. The results suggest that fish in these systems can tolerate higher acidity and inorganic aluminium levels than fish in low DOC streams. But even with the relatively low contemporary deposition load, anthropogenic deposition can cause fish mortality in the most acid-sensitive surface waters in northern Sweden during spring flood. However, the results suggests that it is only in streams with high levels of organically complexed aluminium in combination with a natural pH decline to below 5.0 during the spring where current sulphur deposition can cause irreversible damage to brown trout in the region. This study support earlier studies suggesting that DOC has an ameliorating effect on physiological disturbances in humic waters but the study also shows that surviving fish recover physiologically when the water quality returns to less toxic conditions following a toxic high flow period. The physiological response under natural, pre-industrial conditions was also estimated.

  8. Influence of various acids on the physico–mechanical properties of ...

    Indian Academy of Sciences (India)

    in weight loss and compressive strength values for each acid solution within the test period were recorded. The acid resistance of mortars made from Portland cement was better than the pozzolanic cement incorporated samples after 120 days of acid attack. Keywords. Pozzolanic cement; hydrochloric acid; nitric acid; ...

  9. Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings.

    Science.gov (United States)

    Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2013-09-01

    Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Edible films developed from carboxylic acid cross-linked sesame protein isolate: barrier, mechanical, thermal, crystalline and morphological properties.

    Science.gov (United States)

    Sharma, Loveleen; Sharma, Harish Kumar; Saini, Charanjiv Singh

    2018-02-01

    Films were developed from sesame protein crosslinked with three different carboxylic acids (malic acid, citric acid and succinic acid) at 1, 3 and 5% (w/w, on protein isolate basis). The effect of crosslinking on physical, mechanical, thermal and morphological properties was studied. Succinic acid crosslinked films exhibited least water vapor permeability the highest tensile strength and overall showed superlative properties among other films. X-ray diffraction showed single main crystalline reflection at 20° indicating amorphous structure of films. DSC curves of films indicated single melting peak in the range of 103-161 °C. All films exhibited weight loss in three stages. FTIR exhibited peak at 1700 cm -1 confirming crosslinking reaction between carboxylic acids and protein. Crosslinked films were compact, nonporous and smooth as compared to film from native sesame protein isolate.

  11. Structure Properties and Mechanisms of Action of Naturally Originated Phenolic Acids and Their Derivatives against Human Viral Infections.

    Science.gov (United States)

    Wu, Yi-Hang; Zhang, Bing-Yi; Qiu, Li-Peng; Guan, Rong-Fa; Ye, Zi-Hong; Yu, Xiao-Ping

    2017-01-01

    A great effort has been made to develop efficacious antiviral drugs, but many viral infections are still lack of efficient antiviral therapies so far. The related exploration of natural products to fight viruses has been raised in recent years. Natural compounds with structural diversity and complexity offer a great chance to find new antiviral agents. Particularly, phenolic acids have attracted considerable attention owing to their potent antiviral abilities and unique mechanisms. The aim of this review is to report new discoveries and updates pertaining to antiviral phenolic acids. The relevant references on natural phenolic acids were searched. The antiviral phenolic acids were classified according to their structural properties and antiviral types. Meanwhile, the antiviral characteristics and structure-activity relationships of phenolic acids and their derivatives were summarized. The review finds that natural phenolic acids and their derivatives possessed potent inhibitory effects on multiple virus in humans such as human immunodeficiency virus, hepatitis C virus, hepatitis B virus, herpes simplex virus, influenza virus and respiratory syncytial virus. In particular, caffeic acid/gallic acid and their derivatives exhibited outstanding antiviral properties by a variety of modes of action. Naturally derived phenolic acids especially caffeic acid/gallic acid and their derivatives may be regarded as novel promising antiviral leads or candidates. Additionally, scarcely any of these compounds has been used as antiviral treatment in clinical practice. Therefore, these phenolic acids with diverse skeletons and mechanisms provide us an excellent resource for finding novel antiviral drugs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  12. Molecular mechanisms and clinical applications of nordihydroguaiaretic acid (NDGA) and its derivatives: An update

    Science.gov (United States)

    Lü, Jian-Ming; Nurko, Jacobo; Weakley, Sarah M.; Jiang, Jun; Kougias, Panagiotis; Lin, Peter H.; Yao, Qizhi; Chen, Changyi

    2010-01-01

    Summary Creosote bush, Larrea tridentata, is known as chaparral or greasewood in the United States and as gobernadora or hediondilla in Mexico. Nordihydroguaiaretic acid (NDGA), the main metabolite of the creosote bush, has been shown to have promising applications in the treatment of multiple diseases, including cardiovascular diseases, neurological disorders and cancers. Creosote bush is a promising agent of North American herbal medicine, and it has extensive pharmacological effects and specific mechanisms of actions. This review provides an update of recent in vitro and in vivo research about NDGA and describes experimental studies using NDGA as antioxidant. Also, potential medical uses based on the effects of NDGA on the cardiovascular, immune and neurological systems; cancer; tissue engineering; as well as pharmacokinetics and toxicity are discussed. PMID:20424564

  13. Physicochemical and mechanical properties of paracetamol cocrystal with 5-nitroisophthalic acid.

    Science.gov (United States)

    Hiendrawan, Stevanus; Veriansyah, Bambang; Widjojokusumo, Edward; Soewandhi, Sundani Nurono; Wikarsa, Saleh; Tjandrawinata, Raymond R

    2016-01-30

    We report novel pharmaceutical cocrystal of a popular antipyretic drug paracetamol (PCA) with coformer 5-nitroisophhthalic acid (5NIP) to improve its tabletability. The cocrystal (PCA-5NIP at molar ratio of 1:1) was synthesized by solvent evaporation technique using methanol as solvent. The physicochemical properties of cocrystal were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), fourier transform infrared spectroscopy (FTIR), hot stage polarized microscopy (HSPM) and scanning electron microscopy (SEM). Stability of the cocrystal was assessed by storing them at 40°C/75% RH for one month. Compared to PCA, the cocrystal displayed superior tableting performance. PCA-5NIP cocrystal showed a similar dissolution profile as compared to PCA and exhibited good stability. This study showed the utility of PCA-5NIP cocrystal for improving mechanical properties of PCA. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Evaluation of antibacterial and antibiofilm mechanisms by usnic acid against methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Pompilio, Arianna; Riviello, Antonella; Crocetta, Valentina; Di Giuseppe, Fabrizio; Pomponio, Stefano; Sulpizio, Marilisa; Di Ilio, Carmine; Angelucci, Stefania; Barone, Luana; Di Giulio, Andrea; Di Bonaventura, Giovanni

    2016-10-01

    To evaluate the antibacterial and antibiofilm mechanisms of usnic acid (USN) against methicillin-resistant Staphylococcus aureus from cystic fibrosis patients. The effects exerted by USN at subinhibitory concentrations on S. aureus Sa3 strain was evaluated by proteomic, real-time PCR and electron microscopy analyses. Proteomic analysis showed that USN caused damage in peptidoglycan synthesis, as confirmed by microscopy. Real-time PCR analysis showed that antibiofilm activity of USN is mainly due to impaired adhesion to the host matrix binding proteins, and decreasing lipase and thermonuclease expression. Our data show that USN exerts anti-staphylococcal effects through multitarget inhibitory effects, thus confirming the rationale for considering it 'lead compound' for the treatment of cystic fibrosis infections.

  15. Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab

    2000-03-01

    The interaction of caffeic acid with e{sub aq}{sup -}, (CH{sub 3}){sub 2}(OH) CCH{sub 2}{sup {center_dot}}, CO{sub 2}{sup {center_dot}}{sup -}, H{sup {center_dot}}, {center_dot}OH and N{sub 3}{sup {center_dot}} radicals were studied by {gamma}-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/{center_dot}OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

  16. Investigation on crystalline perfection, mechanical, piezoelectric and ferroelectric properties of L-tartaric acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, G. Senthil, E-mail: nanosen@gmail.com; Ramasamy, P., E-mail: nanosen@gmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Tamilnadu - 603110 (India)

    2014-04-24

    Polar organic nonlinear optical material, L-tartaric acid single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study indicates that the grown crystal crystallized in monoclinic system with space group P2{sub 1}. Crystalline perfection of the crystal has been evaluated by high resolution X-ray diffraction technique and it reveals that the crystal quality is good and free from structural grain boundaries. Mechanical stability of the crystal has been analyzed by Vickers microhardness measurement and it exhibits reverse indentation size effect. Piezoelectric d{sub 33} co-efficient for the crystal has been examined and its value is 47 pC/N. The ferroelectric behaviour of the crystal was analyzed by polarization-electric field hysteresis loop measurement.

  17. Rev-erb agonist improves adverse cardiac remodeling and survival in myocardial infarction through an anti-inflammatory mechanism.

    Directory of Open Access Journals (Sweden)

    Endin Nokik Stujanna

    Full Text Available Rev-erb α, known as nuclear receptor 1D1 (NR1D1, regulates circadian rhythm, modulates glucose and lipid metabolism, and inflammatory response. However, little is known about the effect of Rev-erb agonist on the progression of myocardial infarction (MI and heart failure. To investigate it, wild-type male mice underwent sham-operation or permanent ligation of the left anterior descending coronary artery to create MI model. Rev-erb agonist SR9009 (100 mg/kg/day or vehicle was intraperitoneally administered. Echocardiography was performed to evaluate cardiac function 1 week after surgery. The gene and protein expression levels in the left ventricles (LVs were determined with real-time PCR, western blotting, and immunofluorescence. Moreover, immune cell infiltration into the LVs was analyzed by flow cytometry. Survival rate and reduced LV function were significantly improved by the treatment with SR9009 after MI. The expression level and plasma concentration of brain natriuretic peptide were significantly lower in MI mice treated with SR9009 (MI+SR than in MI mice treated with vehicle (MI+V. Moreover, the mRNA expression levels of inflammatory-related molecules such as Il6, Mcp1, Ly6g, Cd11b, matrix metallopeptidase (Mmp9, and the protein expression levels of phosphorylated NF-κB p65, phosphorylated ERK, and phosphorylated p38 were also significantly lower in MI+SR than in MI+V. Immunofluorescence intensity for MMP-9 was enhanced in the LVs, but was less so in MI+SR than in MI+V. Furthermore, infiltrations of neutrophils and proinflammatory macrophages in the LVs were dramatically increased in MI+V and were significantly suppressed in MI+SR. Rev-erb agonist SR9009 treatment inhibited post-MI mortality and improved cardiac function through modulating inflammation and remodeling process.

  18. Mechanism and kinetics of electrochemical degradation of uric acid using conductive-diamond anodes.

    Science.gov (United States)

    Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed

    2016-12-01

    Uric acid (UA) is one of the principal effluents of urine wastewaters, widely used in agriculture as fertilizer, which is potentially dangerous and biorefractory. Hence, the degradation of UA (2,6,8-trihydroxy purine) in aqueous solution of pH 3.0 has been studied by conductive-diamond electrochemical oxidation. Hydroxyl radicals formed from water oxidation at the surface of boron-doped diamond anodes were the main oxidizing agents. Effects of current density and supporting electrolyte on the degradation rate and process efficiency are assessed. Results show that the increase of current density from 20 to 60 mA cm(-2) leads to a decrease in the efficiency of the electrochemical process. In addition, the best degradation occurred in the presence of NaCl as conductive electrolyte. Interestingly, an almost total mineralization of 50 ppm UA was obtained when anodic oxidation was performed at low current densities (20 mA cm(-2)) and in the presence of NaCl. This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of UA. The identification of UA transformation products was performed by high-performance liquid chromatography (HPLC). HPLC analysis of treated solutions revealed that oxalic acid and urea were the two intermediates found. Oxalic acid was the most persistent product. Based on detected intermediates and bibliographic research, a mechanism of UA mineralization by anodic oxidation has been proposed. Ionic chromatography analysis confirmed the release of [Formula: see text] and [Formula: see text] ions during UA mineralization.

  19. Mechanical properties, morphology, and hydrolytic degradation behavior of polylactic acid / natural rubber blends

    Science.gov (United States)

    Buys, Y. F.; Aznan, A. N. A.; Anuar, H.

    2018-01-01

    Due to its biodegradability and renewability, polylactic acid (PLA) has been receiving enormous attention as a potential candidate to replace petroleum based polymers. However, PLA has limitation due to its inherent brittleness. In order to overcome this limitation, blending PLA with elastomeric materials such as natural rubber (NR) are commonly reported. In previous, several researches on PLA/NR blend had been reported, with most of them evaluated the mechanical properties. On the other hand, study of degradation behavior is significance of importance, as controlling materials degradation is required in some applications. This research studied the effect of blend composition on mechanical properties, morphology development, and hydrolytic degradation behavior of PLA/NR blends. Various compositions of PLA/NR blends were prepared by melt blending technique. Tensile test and impact test of the blends were performed to evaluate the mechanical properties. Addition of NR improved the elongation at break and impact strength of the blends, but reduced the tensile strength and stiffness of the specimens. Dynamic Mechanical Analysis (DMA) measurements of the blends displayed two peaks at temperature -70˚C which corresponded to T g of NR and 65˚C which corresponded to T g of PLA. Field Emission Scanning Electron Microscopy (FE-SEM) micrograph of 70/30 PLA/NR specimen also showed two distinct phases, which lead to indication that PLA/NR blends are immiscible. Hydrolytic degradation behavior was evaluated by measuring the remaining weight of the samples immersed in sodium hydroxide solution for a predetermined times. It was shown that the degradation behavior of PLA/NR blends is affected by composition of the blends, with 100 PLA and 70/30 PLA/NR blend showed the fastest degradation rate and 100 NR displayed the slowest one.

  20. Antinociceptive Activities and the Mechanisms of Anti-Inflammation of Asiatic Acid in Mice

    Directory of Open Access Journals (Sweden)

    Shyh-Shyun Huang

    2011-01-01

    Full Text Available Asiatic acid (AA, a pentacyclic triterpene compound in the medicinal plant Centella asiatica, was evaluated for antinociceptive and anti-inflammatory effects. Treatment of male ICR mice with AA significantly inhibited the numbers of acetic acid-induced writhing responses and the formalin-induced pain in the late phase. In the anti-inflammatory test, AA decreased the paw edema at the 4th and 5th h after λ-carrageenan (Carr administration and increased the activities of catalase (CAT, superoxide dismutase (SOD, and glutathione peroxidase (GPx in the liver tissue. AA decreased the nitric oxide (NO, tumor necrosis factor-α (TNF-α, and interleukin-1β (IL-1β levels on serum level at the 5th h after Carr injection. Western blotting revealed that AA decreased Carr-induced inducible nitric oxide synthase (iNOS, cyclooxygenase (COX-2, and nuclear factor-κB (NF-κB expressions at the 5th h in the edema paw. An intraperitoneal (i.p. injection treatment with AA also diminished neutrophil infiltration into sites of inflammation as did indomethacin (Indo. The anti-inflammatory mechanisms of AA might be related to the decrease in the level of MDA, iNOS, COX-2, and NF-κB in the edema paw via increasing the activities of CAT, SOD, and GPx in the liver.

  1. Citric Acid Metabolism in Resistant Hypertension: Underlying Mechanisms and Metabolic Prediction of Treatment Response.

    Science.gov (United States)

    Martin-Lorenzo, Marta; Martinez, Paula J; Baldan-Martin, Montserrat; Ruiz-Hurtado, Gema; Prado, Jose Carlos; Segura, Julian; de la Cuesta, Fernando; Barderas, Maria G; Vivanco, Fernando; Ruilope, Luis Miguel; Alvarez-Llamas, Gloria

    2017-11-01

    Resistant hypertension (RH) affects 9% to 12% of hypertensive adults. Prolonged exposure to suboptimal blood pressure control results in end-organ damage and cardiovascular risk. Spironolactone is the most effective drug for treatment, but not all patients respond and side effects are not negligible. Little is known on the mechanisms responsible for RH. We aimed to identify metabolic alterations in urine. In addition, a potential capacity of metabolites to predict response to spironolactone was investigated. Urine was collected from 29 patients with RH and from a group of 13 subjects with pseudo-RH. For patients, samples were collected before and after spironolactone administration and were classified in responders (n=19) and nonresponders (n=10). Nuclear magnetic resonance was applied to identify altered metabolites and pathways. Metabolites were confirmed by liquid chromatography-mass spectrometry. Citric acid cycle was the pathway most significantly altered ( P citric acid cycle and deregulation of reactive oxygen species homeostasis control continue its activation after hypertension was developed. A metabolic panel showing alteration before spironolactone treatment and predicting future response of patients is shown. These molecular indicators will contribute optimizing the rate of control of RH patients with spironolactone. © 2017 American Heart Association, Inc.

  2. Biologic plausibility, cellular effects, and molecular mechanisms of eicosapentaenoic acid (EPA) in atherosclerosis.

    Science.gov (United States)

    Borow, Kenneth M; Nelson, John R; Mason, R Preston

    2015-09-01

    Residual cardiovascular (CV) risk remains in dyslipidemic patients despite intensive statin therapy, underscoring the need for additional intervention. Eicosapentaenoic acid (EPA), an omega-3 polyunsaturated fatty acid, is incorporated into membrane phospholipids and atherosclerotic plaques and exerts beneficial effects on the pathophysiologic cascade from onset of plaque formation through rupture. Specific salutary actions have been reported relating to endothelial function, oxidative stress, foam cell formation, inflammation, plaque formation/progression, platelet aggregation, thrombus formation, and plaque rupture. EPA also improves atherogenic dyslipidemia characterized by reduction of triglycerides without raising low-density lipoprotein cholesterol. Other beneficial effects of EPA include vasodilation, resulting in blood pressure reductions, as well as improved membrane fluidity. EPA's effects are at least additive to those of statins when given as adjunctive therapy. In this review, we present data supporting the biologic plausibility of EPA as an anti-atherosclerotic agent with potential clinical benefit for prevention of CV events, as well as its cellular effects and molecular mechanisms of action. REDUCE-IT is an ongoing, randomized, controlled study evaluating whether the high-purity ethyl ester of EPA (icosapent ethyl) at 4 g/day combined with statin therapy is superior to statin therapy alone for reducing CV events in high-risk patients with mixed dyslipidemia. The results from this study are expected to clarify the role of EPA as adjunctive therapy to a statin for reduction of residual CV risk. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  3. Cytoxicity and Apoptotic Mechanism of Ruthenium(II) Amino Acid Complexes in Sarcoma-180 Tumor Cells

    Science.gov (United States)

    Lima, Aliny Pereira; Pereira, Flávia Castro; Almeida, Marcio Aurelio Pinheiro; Mello, Francyelli Mariana Santos; Pires, Wanessa Carvalho; Pinto, Thallita Monteiro; Delella, Flávia Karina; Felisbino, Sérgio Luis; Moreno, Virtudes; Batista, Alzir Azevedo; de Paula Silveira-Lacerda, Elisângela

    2014-01-01

    Over the past several decades, much attention has been focused on ruthenium complexes in antitumor therapy. Ruthenium is a transition metal that possesses several advantages for rational antitumor drug design and biological applications. In the present study, five ruthenium complexes containing amino acids were studied in vitro to determine their biological activity against sarcoma-180 tumor cells. The cytotoxicity of the complexes was evaluated by an MTT assay, and their mechanism of action was investigated. The results demonstrated that the five complexes inhibited the growth of the S180 tumor cell line, with IC50 values ranging from 22.53 µM to 50.18 µM, and showed low cytotoxicity against normal L929 fibroblast cells. Flow cytometric analysis revealed that the [Ru(gly)(bipy)(dppb)]PF6 complex (2) inhibited the growth of the tumor cells by inducing apoptosis, as evidenced by an increased number of Annexin V-positive cells and G0/G1 phase cell cycle arrest. Further investigation showed that complex 2 caused a loss of mitochondrial membrane potential; activated caspases 3, caspase-8, and caspase-9 and caused a change in the mRNA expression levels of caspase 3, caspase-9 as well as the bax genes. The levels of the pro-apoptotic Bcl-2 family protein Bak were increased. Thus, we demonstrated that ruthenium amino acid complexes are promising drugs against S180 tumor cells, and we recommend further investigations of their role as chemotherapeutic agents for sarcomas. PMID:25329644

  4. Cytoxicity and apoptotic mechanism of ruthenium(II amino acid complexes in sarcoma-180 tumor cells.

    Directory of Open Access Journals (Sweden)

    Aliny Pereira Lima

    Full Text Available Over the past several decades, much attention has been focused on ruthenium complexes in antitumor therapy. Ruthenium is a transition metal that possesses several advantages for rational antitumor drug design and biological applications. In the present study, five ruthenium complexes containing amino acids were studied in vitro to determine their biological activity against sarcoma-180 tumor cells. The cytotoxicity of the complexes was evaluated by an MTT assay, and their mechanism of action was investigated. The results demonstrated that the five complexes inhibited the growth of the S180 tumor cell line, with IC50 values ranging from 22.53 µM to 50.18 µM, and showed low cytotoxicity against normal L929 fibroblast cells. Flow cytometric analysis revealed that the [Ru(gly(bipy(dppb]PF6 complex (2 inhibited the growth of the tumor cells by inducing apoptosis, as evidenced by an increased number of Annexin V-positive cells and G0/G1 phase cell cycle arrest. Further investigation showed that complex 2 caused a loss of mitochondrial membrane potential; activated caspases 3, caspase-8, and caspase-9 and caused a change in the mRNA expression levels of caspase 3, caspase-9 as well as the bax genes. The levels of the pro-apoptotic Bcl-2 family protein Bak were increased. Thus, we demonstrated that ruthenium amino acid complexes are promising drugs against S180 tumor cells, and we recommend further investigations of their role as chemotherapeutic agents for sarcomas.

  5. Mechanism of Decarboxylation of Pyruvic Acid in the Presence of Hydrogen Peroxide.

    Science.gov (United States)

    Lopalco, Antonio; Dalwadi, Gautam; Niu, Sida; Schowen, Richard L; Douglas, Justin; Stella, Valentino J

    2016-02-01

    The purpose of this work was to probe the rate and mechanism of rapid decarboxylation of pyruvic acid in the presence of hydrogen peroxide (H2O2) to acetic acid and carbon dioxide over the pH range 2-9 at 25 °C, utilizing UV spectrophotometry, high performance liquid chromatography (HPLC), and proton and carbon nuclear magnetic resonance spectrometry ((1)H, (13)C-NMR). Changes in UV absorbance at 220 nm were used to determine the kinetics as the reaction was too fast to follow by HPLC or NMR in much of the pH range. The rate constants for the reaction were determined in the presence of molar excess of H2O2 resulting in pseudo first-order kinetics. No buffer catalysis was observed. The calculated second-order rate constants for the reaction followed a sigmoidal shape with pH-independent regions below pH 3 and above pH 7 but increased between pH 4 and 6. Between pH 4 and 9, the results were in agreement with a change from rate-determining nucleophilic attack of the deprotonated peroxide species, HOO(-), on the α-carbonyl group followed by rapid decarboxylation at pH values below 6 to rate-determining decarboxylation above pH 7. The addition of H2O2 to ethyl pyruvate was also characterized. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  6. STUDY OF DOUBLE PROTONS MIGRATION MECHANISM IN SUPRAMOLECULAR STRUCTURES OF ACETIC ACID-WATER AND ACETIC ACID-AMMONIA BY AB INITIO METHOD

    Directory of Open Access Journals (Sweden)

    Karna Wijaya

    2010-06-01

    Full Text Available The theoretical study of double protons migration mechanism on acetic acid-water and acetic acid-ammonia associations has been carried out. The research covered determinations the reactant, transition state and product structures. To gain the goal, the research was conducted in three steps, i.e. (i designing the reactant, transition state and product models, (ii optimizing of structures, and (iii calculating of their uncorrected total energy and frequencies with ab initio methods (basis set 6-31G**. All calculations were performed using Hyperchem ver 5.0 for Windows and Gaussian 94W package program. The computational study result showed that the calculated structures were in good agreement with the hypothetical structures.   Keywords: double protons migration, acetic acid, water, ammonia, molecular mechanics and ab-initio

  7. [Research of mechanism of secondary metabolites of phenolic acids in Salvia miltiorrhiza hairy root induced by jasmonate].

    Science.gov (United States)

    Li, Wenyuan; Gao, Wei; Zhao, Jing; Cui, Guanghong; Shao, Aijuan; Huang, Luqi

    2012-01-01

    To study the mechanism of secondary metabolites of some phenolic acids in the hairy roots of Salvia miltiorrhiza induced by methyl jasmonate. The hairy roots of S. miltiorrhiza were induced with methyl jasmonate (100 micromol x L(-1)) and collected at 0, 12, 24, 36 h after treatment. Real-time quantitative PCR was used for detecting the mRNA expression level of the key enzyme genes on the secondary metabolites pathway of rosmarinic acid, while a LC-MS method was developed to determine the content of rosmarinic acid, caffeic acid and salvianolic acid B. The concentration of phenolic acids grew up and accumulated quickly in the hairy roots with exogenous signal molecule MJ induced, and it was showed that the content of CA and RA reached the maximum after 24 h and the content of LAB reached the maximum in 36 h by MJ induced. The induction mechanism may be activated with different levels of RA synthesis in PAL, 4CL, C4H genes on the key enzyme phenylalanine pathway and TAT, HPPR genes on tyrosine pathway. The time of gene expression was different, among them, 4CL and PAL genes were more important. In a word, the result can provide some basis data about the mechanism of secondary metabolites of phenolic acids for further research.

  8. Mechanism of cytotoxic action of perfluorinated acids. III. Disturbance in Ca2+ homeostasis

    International Nuclear Information System (INIS)

    Kleszczynski, Konrad; Skladanowski, Andrzej C.

    2011-01-01

    The global distribution of perfluorinated acids (PFAs) in industry and in household is well known. Their increasing environmental occurrence and biomagnification in the living organisms have drawn growing interests in efforts to describe precisely the mechanisms of action in vitro and in vivo. Our previous investigations widely described lipophilicity-dependent cytotoxicity of PFAs as well as the effect of perfluorination of carbon chain on depolarization of plasma membrane potential, acidification or mitochondrial dysfunctions. In this study we presented in dose- and time-dependent manner the impact of PFAs on calcium homeostasis in HCT116 cells. Comparative analysis of cytosolic [Ca 2+ ] c and mitochondrial calcium [Ca 2+ ] m carried out by flow cytometry revealed distinct uptake of calcium into mitochondria in correlation to increasing lipophilicity of PFAs. Massive accumulation of [Ca 2+ ] m was not accompanied by equivalent loss of [Ca 2+ ] c . Indeed, moderate changes of [Ca 2+ ] c were observed after incubation with 400 μM PFDoDA reaching 29.83% and 49.17% decrease at 4th and 72nd hour, respectively. At the same time, mitochondrial calcium uptake increased from 2- to more than 4-fold comparing with non-treated cells. Incubation with non-fluorinated decanoic acid (DA) did not cause any changes in calcium homeostasis. Presented data show that PFAs-induced perturbations in calcium distribution seem to be a missing link related to mitochondria dysfunction playing a crucial role in determination of apoptotic cell death. Complete scheme for the mechanism of cytotoxic action of PFAs has been included.

  9. The mechanism and kinetics of the electrochemical cleavage of azo bond of 2-hydroxy-5-sulfophenyl-azo-benzoic acids

    International Nuclear Information System (INIS)

    Mandic, Zoran; Nigovic, Biljana; Simunic, Branimir

    2004-01-01

    The electrochemical reduction of 2-hydroxy-5-[(4-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(3-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(2-sulfophenyl)azo]benzoic acid and 2-hydroxy-5-azo-benzoic acid has been carried out in aqueous solutions at glassy carbon electrode using cyclic voltammetry and chronoamperometry. The position of sulfo substituent relative to azo bridge as well as pH of the solution have significant impact on the electrochemical behavior of these compounds. It has been proposed that these compounds are reduced predominantly as hydrazone tautomers resulting in corresponding hydrazo compounds. The overall electrochemical reduction follows DISP2 mechanism, ultimately leading to the 5-amino salicylic acid and sulfanilic acid. The rate determining step is the homogenous redox reaction between intermediate hydrazo compound and 5-amino salicylic acid quinoneimine. The mechanism is proposed in which activated complex of 5-amino salicylic acid quinoneimine and intermediate hydrazo compound is formed with the simultaneous loss of one proton

  10. Mechanisms of Oxidative Damage in Multiple Sclerosis and Neurodegenerative Diseases: Therapeutic Modulation via Fumaric Acid Esters

    Directory of Open Access Journals (Sweden)

    Ralf Gold

    2012-09-01

    Full Text Available Oxidative stress plays a crucial role in many neurodegenerative conditions such as Alzheimer’s disease, amyotrophic lateral sclerosis and Parkinson’s as well as Huntington’s disease. Inflammation and oxidative stress are also thought to promote tissue damage in multiple sclerosis (MS. Recent data point at an important role of anti-oxidative pathways for tissue protection in chronic-progressive MS, particularly involving the transcription factor nuclear factor (erythroid-derived 2-related factor 2 (Nrf2. Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for MS treatment. Here, fumaric acid esters (FAE are a new, orally available treatment option which had already been tested in phase II/III MS trials demonstrating beneficial effects on relapse rates and magnetic resonance imaging markers. In vitro, application of dimethylfumarate (DMF leads to stabilization of Nrf2, activation of Nrf2-dependent transcriptional activity and abundant synthesis of detoxifying proteins. Furthermore, application of FAE involves direct modification of the inhibitor of Nrf2, Kelch-like ECH-associated protein 1. On cellular levels, the application of FAE enhances neuronal survival and protects astrocytes against oxidative stress. Increased levels of Nrf2 are detected in the central nervous system of DMF treated mice suffering from experimental autoimmune encephalomyelitis (EAE, an animal model of MS. In EAE, DMF ameliorates the disease course and improves preservation of myelin, axons and neurons. Finally, Nrf2 is also up-regulated in the spinal cord of autopsy specimens from untreated patients with MS, probably as part of a naturally occurring anti-oxidative response. In summary, oxidative stress and anti-oxidative pathways are important players in MS pathophysiology and constitute a promising target for future MS therapies like FAE.

  11. MicroRNA networks regulated by all-trans retinoic acid and Lapatinib control the growth, survival and motility of breast cancer cells

    Science.gov (United States)

    Kurosaki, Mami; Paroni, Gabriela; Zanetti, Adriana; Gianni, Maurizio; Bolis, Marco; Lupi, Monica; Tsykin, Anna; Goodall, Gregory J.; Garattini, Enrico

    2015-01-01

    SKBR3-cells, characterized by ERBB2/RARA co-amplification, represent a subgroup of HER2+ breast-cancers sensitive to all-trans retinoic acid (ATRA) and Lapatinib. In this model, the two agents alone or in combination modulate the expression of 174 microRNAs (miRs). These miRs and predicted target-transcripts are organized in four interconnected modules (Module-1 to -4). Module-1 and Module-3 consist of ATRA/Lapatinib up-regulated and potentially anti-oncogenic miRs, while Module-2 contains ATRA/Lapatinib down-regulated and potentially pro-oncogenic miRs. Consistent with this, the expression levels of Module-1/-3 and Module-2 miRs are higher and lower, respectively, in normal mammary tissues relative to ductal-carcinoma-in-situ, invasive-ductal-carcinoma and metastases. This indicates associations between tumor-progression and the expression profiles of Module-1 to -3 miRs. Similar associations are observed with tumor proliferation-scores, staging, size and overall-survival using TCGA (The Cancer Genome Atlas) data. Forced expression of Module-1 miRs, (miR-29a-3p; miR-874-3p) inhibit SKBR3-cell growth and Module-3 miRs (miR-575; miR-1225-5p) reduce growth and motility. Module-2 miRs (miR-125a; miR-193; miR-210) increase SKBR3 cell growth, survival and motility. Some of these effects are of general significance, being replicated in other breast cancer cell lines representing the heterogeneity of this disease. Finally, our study demonstrates that HIPK2-kinase and the PLCXD1-phospholipase-C are novel targets of miR-193a-5p/miR-210-3p and miR-575/miR-1225-5p, respectively. PMID:25961594

  12. Effect of milk fermentation by kefir grains and selected single strains of lactic acid bacteria on the survival of Mycobacterium bovis BCG.

    Science.gov (United States)

    Macuamule, C L S; Wiid, I J; van Helden, P D; Tanner, M; Witthuhn, R C

    2016-01-18

    Mycobacterium bovis that causes Bovine tuberculosis (BTB) can be transmitted to humans thought consumption of raw and raw fermented milk products from diseased animals. Lactic acid bacteria (LAB) used in popular traditional milk products in Africa produce anti-microbial compounds that inhibit some pathogenic and spoilage bacteria. M. bovis BCG is an attenuated non-pathogenic vaccine strain of M. bovis and the aim of the study was to determine the effect of the fermentation process on the survival of M. bovis BCG in milk. M. bovis BCG at concentrations of 6 log CFU/ml was added to products of kefir fermentation. The survival of M. bovis BCG was monitored at 12-h intervals for 72 h by enumerating viable cells on Middlebrook 7H10 agar plates enriched with 2% BD BACTEC PANTA™. M. bovis BCG was increasingly reduced in sterile kefir that was fermented for a period of 24h and longer. In the milk fermented with kefir grains, Lactobacillus paracasei subsp. paracasei or Lactobacillus casei, the viability of M. bovis BCG was reduced by 0.4 logs after 24h and by 2 logs after 48 h of fermentation. No viable M. bovis BCG was detected after 60 h of fermentation. Results from this study show that long term fermentation under certain conditions may have the potential to inactivate M. bovis BCG present in the milk. However, to ensure safety of fermented milk in Africa, fermentation should be combined with other hurdle technologies such as boiling and milk pasteurisation. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Retinol Promotes In Vitro Growth of Proximal Colon Organoids through a Retinoic Acid-Independent Mechanism.

    Directory of Open Access Journals (Sweden)

    Taichi Matsumoto

    Full Text Available Retinol (ROL, the alcohol form of vitamin A, is known to control cell fate decision of various types of stem cells in the form of its active metabolite, retinoic acid (RA. However, little is known about whether ROL has regulatory effects on colonic stem cells. We examined in this study the effect of ROL on the growth of murine normal colonic cells cultured as organoids. As genes involved in RA synthesis from ROL were differentially expressed along the length of the colon, we tested the effect of ROL on proximal and distal colon organoids separately. We found that organoid forming efficiency and the expression level of Lgr5, a marker gene for colonic stem cells were significantly enhanced by ROL in the proximal colon organoids, but not in the distal ones. Interestingly, neither retinaldehyde (RAL, an intermediate product of the ROL-RA pathway, nor RA exhibited growth promoting effects on the proximal colon organoids, suggesting that ROL-dependent growth enhancement in organoids involves an RA-independent mechanism. This was confirmed by the observation that an inhibitor for RA-mediated gene transcription did not abrogate the effect of ROL on organoids. This novel role of ROL in stem cell maintenance in the proximal colon provides insights into the mechanism of region-specific regulation for colonic stem cell maintenance.

  14. Kinetics and mechanism of sphalerite leaching by sodium nitrate in sulphuric acid solution

    Directory of Open Access Journals (Sweden)

    Sokić M.

    2012-01-01

    Full Text Available Interest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time on the leaching degree of zinc were investigated and kinetic analysis of the process was accomplished. With temperature increasing from 60 to 90°C, the zinc leaching increased from 25.23% to 71.66% after 2 hours, i.e. from 59.40% to 99.83% after 4 hours. The selected kinetic model indicated that the diffusion through the product layer was the rate-controlling step during the sphalerite leaching. The activation energy was determined to be 55 kJ/mol in the temperature range 60-90°C. XRD, light microscopy and SEM/EDX analyses of the complex concentrate and leach residue confirmed formation of elemental sulphur and diffusion-controlled leaching mechanism.

  15. Studies on the mechanical properties of woven jute fabric reinforced poly(l-lactic acid composites

    Directory of Open Access Journals (Sweden)

    G.M. Arifuzzaman Khan

    2016-01-01

    Full Text Available Development of ecofriendly biocomposites to replace non-biodegradable synthetic fiber composites is the main objective of this study. To highlight the biocomposites as a perfect replacement, the plain woven jute fabric (WJF reinforced poly(l-lactic acid (PLLA composites were prepared by the hot press molding method. The influence of woven structure and direction on the mechanical properties i.e. tensile, flexural and impact properties was investigated. The average tensile strength (TS, tensile modulus (TM, flexural strength (FS, flexural modulus (FM, and impact strength (IS of untreated woven jute composite (in warp direction were improved about 103%, 211%, 95.2%, 42.4% and 85.9%, respectively and strain at maximum tensile stress for composite samples was enhanced by 11.7%. It was also found that the strengths and modulus of composites in warp direction are higher than those in weft direction. WJF composites in warp and weft directions presented superior mechanical properties than non-woven jute fabric (NWJF composites. Chemical treatment of jute fabric through benzoylation showed a positive effect on the properties of composites. Morphological studies by SEM demonstrated that better adhesion between the treated fabric and PLLA was achieved.

  16. [Mechanism of action of combined extremely weak magnetic field on aqueous solution of amino acid].

    Science.gov (United States)

    Zhadin, M N; Bakharev, B V; Bobkova, N V

    2014-01-01

    The fundamental physical mechanisms of resonance action of an extremely weak (40 nT) alternating magnetic field at the cyclotron frequency combined with a weak (40 μT) static magnetic field, on living systems are analyzed in the present work. The experimental effects of such sort of magnetic fields were described in different papers: the very narrow resonant peaks in electrical conductivity of the aqueous solutions in the in vitro experiments and the biomedical in vivo effects on living animals of magnetic fields with frequencies tuned to some amino acids. The existing experimental in vitro data had a good repeatability in different laboratories and countries. Unfortunately, for free ions such sort of effects are absolutely impossible because the dimensions of an ion rotation radius should be measured by meters at room temperature and at very low static magnetic fields used in all the above experiments. Even for bound ions these effects should be also absolutely impossible from the positions of classic physics because of rather high viscosity of biological liquid media (blood plasma, cerebrospinal liquid, cytoplasm). Only modern quantum electrodynamics of condensed media opens the new ways for solving these problems. The proposed article is devoted to analysis of quantum mechanisms of these effects.

  17. In vitro investigation of intestinal transport mechanism of silicon, supplied as orthosilicic acid-vanillin complex.

    Science.gov (United States)

    Sergent, Thérèse; Croizet, Karine; Schneider, Yves-Jacques

    2017-02-01

    Silicon (Si) is one of the most abundant trace elements in the body. Although pharmacokinetics data described its absorption from the diet and its body excretion, the mechanisms involved in the uptake and transport of Si across the gut wall have not been established. Caco-2 cells were used as a well-accepted in vitro model of the human intestinal epithelium to investigate the transport, across the intestinal barrier in both the absorption and excretion directions, of Si supplied as orthosilicic acid stabilized by vanillin complex (OSA-VC). The transport of this species was found proportional to the initial concentration and to the duration of incubation, with absorption and excretion mean rates similar to those of Lucifer yellow, a marker of paracellular diffusion, and increasing in the presence of EGTA, a chelator of divalents cations including calcium. A cellular accumulation of Si, polarized from the apical side of cells, was furthermore detected. These results provide evidence that Si, ingested as a food supplement containing OSA-VC, crosses the intestinal mucosa by passive diffusion via the paracellular pathway through the intercellular tight junctions and accumulates intracellularly, probably by an uptake mechanism of facilitated diffusion. This study can help to further understand the kinetic of absorption of Si. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Swelling, Mechanics, and Thermal/Chemical Stability of Hydrogels Containing Phenylboronic Acid Side Chains

    Directory of Open Access Journals (Sweden)

    Arum Kim

    2017-12-01

    Full Text Available We report here studies of swelling, mechanics, and thermal stability of hydrogels consisting of 20 mol % methacrylamidophenylboronic acid (MPBA and 80 mol % acrylamide (AAm, lightly crosslinked with methylenebisacrylamide (Bis. Swelling was measured in solutions of fixed ionic strength, but with varying pH values and fructose concentrations. Mechanics was studied by compression and hold. In the absence of sugar or in the presence of fructose, the modulus was mostly maintained during the hold period, while a significant stress relaxation was seen in the presence of glucose, consistent with reversible, dynamic crosslinks provided by glucose, but not fructose. Thermal stability was determined by incubating hydrogels at pH 7.4 at room temperature, and 37, 50, and 65 °C, and monitoring swelling. In PBS (phosphate buffered saline solutions containing 9 mM fructose, swelling remained essentially complete for 50 days at room temperature, but decreased substantially with time at the higher temperatures, with accelerated reduction of swelling with increasing temperature. Controls indicated that over long time periods, both the MPBA and AAm units were experiencing conversion to different species.

  19. Mechanical, thermal and morphological properties of poly(lactic acid)/ethylene-butyl acrylate copolymer nanocomposites

    Science.gov (United States)

    Wacharawichanant, S.; Hoysang, P.; Ratchawong, S.

    2017-07-01

    This paper reports a melt blend of poly(lactic acid) (PLA)/ethylene-butyl acrylate copolymer (EBAC) with organoclay content at 3 phr. The mechanical, thermal and morphological properties of PLA/EBAC blends and nanocomposites were investigated. The morphological analysis revealed EBAC phase dispersed as a spherical domain in PLA matrix and the domain size of EBAC dispersed phase increased with increasing EBAC content. The addition of organoclay could improve the miscibility of PLA/EBAC blends due to the decrease of domain size of EBAC dispersed phase. The mechanical properties indicated that the strain at break and impact strength of PLA increased when added EBAC, but Young’s modulus and tensile strength decreased. Storage modulus increased with the addition of organoclay to the PLA/EBAC blends. The thermal properties found that the incorporation of organoclay in the PLA/EBAC blends did not effect on the glass transition temperature and melting temperature values relative to PLA. The degradation temperature of PLA improved with the addition of EBAC. This indicated that EBAC has more thermal stability and degradation temperature than PLA. From X-ray diffraction patterns displayed the characteristic peak in PLA/EBAC/organoclay nanocomposites appeared at the lower angle, which indicated the dispersed clay is intercalated in the polymer matrix. However, second-order diffraction peak appeared at the higher angle indicated that there was partially the conventional composite.

  20. Processing Conditions, Thermal and Mechanical Responses of Stretchable Poly (Lactic Acid)/Poly (Butylene Succinate) Films.

    Science.gov (United States)

    Fortunati, Elena; Puglia, Debora; Iannoni, Antonio; Terenzi, Andrea; Kenny, José Maria; Torre, Luigi

    2017-07-16

    Poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) based films containing two different plasticizers [Acetyl Tributyl Citrate (ATBC) and isosorbide diester (ISE)] at three different contents (15 wt %, 20 wt % and 30 wt %) were produced by extrusion method. Thermal, morphological, mechanical and wettability behavior of produced materials was investigated as a function of plasticizer content. Filmature parameters were also adjusted and optimized for different formulations, in order to obtain similar thickness for different systems. Differential scanning calorimeter (DSC) results and evaluation of solubility parameter confirmed that similar miscibility was obtained for ATBC and ISE in PLA, while the two selected plasticizers resulted as not efficient for plasticization of PBS, to the limit that the PBS-30ATBC resulted as not processable. On the basis of these results, isosorbide-based plasticizer was considered a suitable agent for modification of a selected blend (PLA/PBS 80:20) and two mixing approaches were used to identify the role of ISE in the plasticization process: results from mechanical analysis confirmed that both produced PLA-PBS blends (PLA85-ISE15)-PBS20 and (PLA80-PBS20)-ISE15 could guarantee advantages in terms of deformability, with respect to the PLA80-PBS20 reference film, suggesting that the promising use of these stretchable PLA-PBS based films plasticized with isosorbide can provide novel solutions for food packaging applications.

  1. Antifungal activity of salicylic acid against Penicillium expansum and its possible mechanisms of action.

    Science.gov (United States)

    da Rocha Neto, Argus Cezar; Maraschin, Marcelo; Di Piero, Robson Marcelo

    2015-12-23

    Apple is a fruit widely produced and consumed around the world. Blue mold (Penicillium expansum) is one of the main postharvest diseases in apples, leading to a wide use of fungicides and the search for alternative products. The aim of this study was to assess the effect of salicylic acid (SA) against P. expansum, elucidating its mechanisms of action. The antimicrobial effect was determined by exposing conidia to a 2.5 mM SA solution for 0 to 120 min, followed by incubation. The effect of pH on the efficacy of SA against P. expansum was assessed both in vitro and in situ. The action mechanisms were investigated through fluorescence assays, measurement of protein leakage, lipid damage, and transmission electronic microscopy. SA was capable of inhibiting 90% of the fungal germination after 30 min, causing damage to the conidial plasma membrane and leading to protein leakage up to 3.2 μg of soluble protein per g of mycelium. The pH of the SA solution affected the antimicrobial activity of this secondary metabolite, which inhibited the germination of P. expansum and the blue mold incidence in apples in solutions with pH≤3 by 100%, gradually losing its activity at higher pH. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. The effects of sucrose on the mechanical properties of acid milk proteins-kappa-carrageenan gels

    Directory of Open Access Journals (Sweden)

    E. Sabadini

    2006-03-01

    Full Text Available Mechanical properties have been widely correlated with textural characteristics to determine the interactions during the process formation of dairy gel. These interactions are strongly affected by process conditions and system composition. In the present study, the rheological of acid-induced protein dairy gels with (2(7-3 and without (2(6-2 sucrose and subjected to small and large deformations were studied using an experimental design. The independent variables were the sodium caseinate, whey protein concentrate (WPC, carrageenan and sucrose concentrations as well as stirring speed and heat treatment time and temperature. Mechanical deformation tests were performed at 0.1, 1, 5, and 9 mm/s up to 80% of initial height. A heavy dependence of rupture stress on increasing crosshead speed and the formation of harder gels with the addition of sucrose were observed. Moreover the elastic and viscous moduli, obtained by fitting the Maxwell model to stress relaxation data, increased with increasing addition of sucrose. These results can be explained by preferential hydration of the casein with sucrose, causing an induction of casein-polysaccharide and casein-casein interactions.

  3. Transcriptomic analysis reveals the metabolic mechanism of L-ascorbic acid in Ziziphus jujuba Mill.

    Directory of Open Access Journals (Sweden)

    Chunmei eZhang

    2016-02-01

    Full Text Available Chinese jujube (Ziziphus jujuba Mill. is the most economically important member of the Rhamnaceae family and contains a high concentration of ascorbic acid (AsA. To explore the metabolic mechanism of AsA accumulation, we investigated the abundance of AsA in the fruit development stages, the leaf and flower of Z. jujuba cv Junzao, and the mature fruit of one type of wild jujube (Z. jujuba var. spinosa Hu, Yanchuan sour jujube. And the expression patterns of genes involved in AsA biosynthesis, degradation and recycling were analyzed. The result showed that AsA biosynthesis during early fruit development (the enlargement stage is the main reason for jujube high accumulation. The L-galactose pathway plays a predominant role in the biosynthesis of AsA during jujube fruit development, and the genes GMP1, GME1, GGP, and GaLDH involved in the determination of AsA concentration during fruit development and in different genotypes; the myo-inositol pathway along with the genes GME2 and GMP2 in the L-galactose pathway play a compensatory role in maintaining AsA accumulation during the ripening stage. These findings enhance our understanding of the molecular mechanism in regulating AsA accumulation for jujube.

  4. Final report: Hydraulic mechanisms of survival and mortality during drought in pinon-juniper woodlands of southwestern USA

    Energy Technology Data Exchange (ETDEWEB)

    Pockman, William [Univ. of New Mexico, Albuquerque, NM (United States)

    2016-11-23

    The goal of this project was to use rainfall manipulation of an intact pinon-juniper woodland in central New Mexico to understand the mechanisms that control the response of these species to extremes of rainfall. Experimental plots were installed in a pinon-juniper woodland at the Sevilleta National Wildlife Refuge and treatments were imposed in August 2007. Treatments consisted of 1) a Drought treatment imposed by diverting approximately 45% of precipitation away from the plot, 2) and Irrigation treatment imposed by applying six 19 mm simulated rainfall events at regular intervals during the growing season, 3) a Cover Control treatment designed to assess the impact of the plastic troughs constructed on Drought plots without imposing the rainfall diversion, and 4) an untreated control that received no modification. Extensive pinon mortality was observed beginning one year after the start of drought treatment on hillslope plots, while a third drought plot on deeper soils did not exhibit pinon mortality until the fifth year of drought treatment. Pinon mortality occurred in the context of high levels of bark beetle activity, motivating the installation of two additional plots in 2010: a control plot and a drought plot built to the same standards as the original treatments but with bark beetle control maintained by pesticide application to the bole of target trees from 2010 - 2016. Although the drought treatment created similar conditions to those experienced on hillslope drought plots, the drought plot with bark beetle control exhibited no pinon mortality for 5 years even in the presence of high regional bark beetle activity in 2012/13. One of the goals of the research was to identify the mechanism of drought-induced mortality in pinon and juniper: 1) mortality due to catastrophic failure of water transport through plant tissues (hydraulic failure), 2) mortality due to limitations in carbon uptake (carbon starvation) and 3) either of the first two mechanisms with the

  5. Progress in engineering acid stress resistance of lactic acid bacteria.

    Science.gov (United States)

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-02-01

    Lactic acid bacteria (LAB) are widely used for the production of a variety of fermented foods, and are considered as probiotic due to their health-promoting effect. However, LAB encounter various environmental stresses both in industrial fermentation and application, among which acid stress is one of the most important survival challenges. Improving the acid stress resistance may contribute to the application and function of probiotic action to the host. Recently, the advent of genomics, functional genomics and high-throughput technologies have allowed for the understanding of acid tolerance mechanisms at a systems level, and many method to improve acid tolerance have been developed. This review describes the current progress in engineering acid stress resistance of LAB. Special emphasis is placed on engineering cellular microenvironment (engineering amino acid metabolism, introduction of exogenous biosynthetic capacity, and overproduction of stress response proteins) and maintaining cell membrane functionality. Moreover, strategies to improve acid tolerance and the related physiological mechanisms are also discussed.

  6. Kinetics and mechanism of the oxidation of formic and oxalic acids ...

    Indian Academy of Sciences (India)

    Unknown

    carbon dioxide. The reaction is first order with respect to BTMACI, zinc chloride and organic acid. Oxidation of deuteriated formic acid indicates the presence of a kinetic ... in glacial acetic acid, in the presence of zinc chloride have been described and their ... Oxidation of acids by benzyltrimethyl ammonium dichloroiodate.

  7. THE EFFECT OF KETAMINE AND ITS COMBINATION WITH INDOL-2-CARBOXYLIC ACID AND CAROVERINE ON SURVIVAL TIME OF MICE WITH EXPERIMENTAL TETANUS

    Directory of Open Access Journals (Sweden)

    Indira Mujezinović

    2017-12-01

    Full Text Available Tetanus, also known as lockjaw, is a very dangerous infectious acute, usually afebrile disease characterized by muscle spasms, affecting humans and various animal species. The causative agent of the disease is bacteria Clostridium tetani. This bacteria produces a specific neurotoxin known as Tetanus toxin, which consists of two components: tetanospasmin and tetanolysin. Light (L chains of tetanospamin cleavage synaptobrevin, an integral membrane component of the synaptic vesicles, which in turn prevent release of the inhibitory neurotransmitter γ-aminobutyric acid (GABA into the synaptic cleft. The α- motor neurons are, therefore, under no inhibitory control as a result of which they undergo sustained excitatory discharge causing the characteristic motor spasms of tetanus. In this research, we attempted to normalize the disorders caused by tetanus toxin by using ketamine, a non-competitive antagonist of aspartate (at doses of 5, 10, 44 and 100 mg/kg of body weight – b.w., alone and in combination with indol-2-carboxylic acid, a competitive antagonist of aspartate (at a dose of 10 mg/kg b.w. and caroverine, a non-competitive antagonist of glutamate (at a dose of 1.2 mg/kg b.w.. Experiments were conducted on the albino mice of both sexes, weighing around 20-25 g. Experimental tetanus was induced by application of tetanus toxin. The administration of ketamine, alone and in combination with indol-2-carboxylic acid and caroverine was carried out 24 hours after administration of tetanus toxin once per day, until the mice died. It was found that ketamine had an effect only at a dose of 10 mg/kg b.w., which slightly prolonged the LD50 periodin experimental group of mice, compared to the control group of mice with experimental tetanus. Thus, it can be concluded that administration of ketamine in this dose proved to be only slightly effective. On the other hand, combination of ketamine with indol-2-carboxylic acid slightly extended the survival time

  8. Mechanical and electrochemical properties of an IPMC actuator with palladium electrodes in acid and alkaline solutions

    Science.gov (United States)

    Aoyagi, Wataru; Omiya, Masaki

    2013-05-01

    An ionic polymer-metal composite (IPMC) actuator, which consists of a thin perfluorinated ionomer membrane and electrodes plated on both surfaces, undergoes a large bending motion when a low electric field is applied across its thickness. IPMC actuators are lightweight and soft and can operate in solutions. They are thus promising for a wide range of applications including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. The deformation behavior of IPMC actuators depends on the pH of the working solution. However, their basic mechanism is not well understood. Therefore, this study investigates the deformation mechanism of an IPMC actuator with palladium electrodes in various pH solutions. The tip displacements of IPMC actuators were measured under a step voltage in various pH solutions. Cyclic voltammetry (CV) and alternating-current (AC) impedance measurements were then performed to investigate the effects of pH on the electrochemical properties of IPMC actuators. The responses to a step voltage indicate that the deformation behavior of an IPMC actuator depends on the pH: a lower pH gives a larger maximum tip displacement and more pronounced relaxation. In CV measurements, a lower pH results in more active reduction on the palladium electrode. In AC impedance measurements, a lower pH leads to a greater charge transfer resistance and a smaller double layer capacitance in an acid solution. Based on these mechanical and electrochemical measurements, we conclude that the maximum tip displacement and relaxation are governed by reduction on the palladium electrode and that the residual tip displacement is related to the charge transfer resistance and the double layer capacitance. These results are helpful for the use and control of IPMC actuators.

  9. Adsorption Mechanisms of Dodecylbenzene Sulfonic Acid by Corn Straw and Poplar Leaf Biochars.

    Science.gov (United States)

    Zhao, Nan; Yang, Xixiang; Zhang, Jing; Zhu, Ling; Lv, Yizhong

    2017-09-22

    Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer-Emmett-Teller N₂ surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA). The microscopic adsorption mechanisms were studied by using infrared spectra, 13 C-nuclear magnetic resonance spectra, and electron spin resonance spectra. The surface area and pore volume of C700 (375.89 m²/g and 0.2302 cm³/g) were the highest among all samples. Elemental analysis results showed that corn straw biochars had a higher aromaticity and carbon to nitrogen (C/N) ratio than the poplar leaf biochars. High temperature caused the increase of carbon content and the decrease of oxygen content, which also gave the biochars a higher adsorption rate. Pseudo-second order kinetic provided a better fit with the experimental data. Adsorption isotherm experiments showed that the adsorption isotherm of C300 fit the linear model. For other biochars, the adsorption isotherms fitted Langmuir model. Biochars with high temperatures exhibited enhanced adsorption capacity compared with ones at low temperatures. The q max values of biochars to DBSA followed the order of P700 > C700 > P300. The adsorption mechanisms were complex, including partition, anion exchange, the formation of H bonds, covalent bonds, and charge transfer. The adsorption by covalent bonding might be the key mechanism determining the adsorption capacity of P700.

  10. Adsorption Mechanisms of Dodecylbenzene Sulfonic Acid by Corn Straw and Poplar Leaf Biochars

    Directory of Open Access Journals (Sweden)

    Nan Zhao

    2017-09-01

    Full Text Available Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700. Brunaer–Emmett–Teller N2 surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA. The microscopic adsorption mechanisms were studied by using infrared spectra, 13C-nuclear magnetic resonance spectra, and electron spin resonance spectra. The surface area and pore volume of C700 (375.89 m2/g and 0.2302 cm3/g were the highest among all samples. Elemental analysis results showed that corn straw biochars had a higher aromaticity and carbon to nitrogen (C/N ratio than the poplar leaf biochars. High temperature caused the increase of carbon content and the decrease of oxygen content, which also gave the biochars a higher adsorption rate. Pseudo-second order kinetic provided a better fit with the experimental data. Adsorption isotherm experiments showed that the adsorption isotherm of C300 fit the linear model. For other biochars, the adsorption isotherms fitted Langmuir model. Biochars with high temperatures exhibited enhanced adsorption capacity compared with ones at low temperatures. The qmax values of biochars to DBSA followed the order of P700 > C700 > P300. The adsorption mechanisms were complex, including partition, anion exchange, the formation of H bonds, covalent bonds, and charge transfer. The adsorption by covalent bonding might be the key mechanism determining the adsorption capacity of P700.

  11. Mechanism of Decomposition of Surface Ethoxy Species to Ethene and Acidic OH Groups on H-ZSM-5.

    Science.gov (United States)

    Kondo, Junko N; Yamazaki, Hiroshi; Osuga, Ryota; Yokoi, Toshiyuki; Tatsumi, Takashi

    2015-06-18

    The reaction mechanism of the decomposition of ethoxy species to ethene and acidic OH groups on H-ZSM-5 was studied by IR spectroscopy using isotope-labeled ethanol. The concerted mechanism occurring on both the ethoxy (acid) site and the counterpart lattice oxygen was suggested by GC-MS analysis of evolved d2-ethene and IR observation of the recovery of OH s groups on acid sites from the decomposition of CH3CD2O- ethoxy species. The concerted mechanism was further confirmed by the estimation of activation energy for decomposition of CH3CH2O-, CH3CD2O-, and CD3CD2O- ethoxy species, 122 ± 3, 125 ± 3, and 140 ± 5 kJ mol(-1), respectively, where the kinetic isotope effect was observed for the cleavage of the CH or CD bond of the methyl group of the ethoxy species.

  12. Survival analysis

    International Nuclear Information System (INIS)

    Badwe, R.A.

    1999-01-01

    The primary endpoint in the majority of the studies has been either disease recurrence or death. This kind of analysis requires a special method since all patients in the study experience the endpoint. The standard method for estimating such survival distribution is Kaplan Meier method. The survival function is defined as the proportion of individuals who survive beyond certain time. Multi-variate comparison for survival has been carried out with Cox's proportional hazard model

  13. Ion pair formation as a possible mechanism for the enhancement effect of lauric acid on the transdermal permeation of ondansetron.

    Science.gov (United States)

    Dimas, Dimitrios A; Dallas, Paraskevas P; Rekkas, Dimitrios M

    2004-08-01

    Transdermal application can be an alternative drug delivery route for ondansetron, an antiemetic drug. Previous studies found that fatty acids, namely oleic and lauric, were the most effective penetration enhancers. The aim of this study was to investigate the formation of an ion pair between ondansetron and lauric acid as a possible mechanism of its enhancing action. Several techniques were used to reveal the formation of an ion pair complex. Partitioning experiments, where the n-octanol/water coefficient was measured, showed an increase in the distribution coefficient in the presence of the acid, possibly as a result of the formation of more lipophilic ion pairs between the charged molecules of ondansetron and lauric acid. Further evidence of complex formation between ondansetron and lauric acid, was gained from the 13C-nuclear magnetic resonance (13C-NMR) spectra of ondansetron, lauric acid, and their mixture (molar ratio 1:1). The NMR spectra revealed alterations to the magnetic environment of the carbon atoms adjacent to the ionized group, which are the carbonyl group of the acid and the nitrogen of the imidazole ring of ondansetron. This evidence substantiates the theory of ion pair formation. Finally, thermal analysis of the binary mixtures of ondansetron and lauric acid revealed the formation of an additional compound, with different melting point from pure ondansetron and lauric acid, which is thermodynamically favored.

  14. Retention Mechanisms of Citric Acid in Ternary Kaolinite-Fe(III)-Citrate Acid Systems Using Fe K-edge EXAFS and L3,2-edge XANES Spectroscopy

    Science.gov (United States)

    Yang, Jianjun; Wang, Jian; Pan, Weinan; Regier, Tom; Hu, Yongfeng; Rumpel, Cornelia; Bolan, Nanthi; Sparks, Donald

    2016-01-01

    Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorption and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. These findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils. PMID:27212680

  15. Alteration of oxidative phosphorylation as a possible mechanism of the antifungal action of p-coumaric acid against Botrytis cinerea.

    Science.gov (United States)

    Morales, J; Mendoza, L; Cotoras, M

    2017-10-01

    The aim of this study was to analyse the mechanism of action of p-coumaric acid against isolate B05·10 of Botrytis cinerea. For this purpose, the effect of this compound on cell membrane, cell wall and oxidative phosphorylation was determined. Induction of oxidative stress triggered by this compound was also studied. p-coumaric acid showed antifungal effect on the mycelial growth. Additionally, the compound was able to retard the germination of Botrytis cinerea conidia. The mechanism of action of this compound was analysed using fluorescent probes. p-Coumaric acid did not affect the integrity of cell wall and plasmatic membrane and neither produced oxidative stress. Finally, it was shown that the compound produced an increase in oxygen consumption. p-coumaric acid performs as a mitochondrial uncoupler in B. cinerea. Its role as an uncoupler of oxidative phosphorylation could be explained to its acidic, nonpolar and planar characteristics. These structural and chemical characteristics would favour ability of p-coumaric acid to pass through cellular membranes. Plant secondary metabolites can be used as an alternative way to control phytopathogenic fungi. The knowledge of the action mechanism of these compounds can contribute to design modified molecules with higher antifungal activity. © 2017 The Society for Applied Microbiology.

  16. New Insights Into the Mechanisms and Biological Roles of D-Amino Acids in Complex Eco-Systems

    Science.gov (United States)

    Aliashkevich, Alena; Alvarez, Laura; Cava, Felipe

    2018-01-01

    In the environment bacteria share their habitat with a great diversity of organisms, from microbes to humans, animals and plants. In these complex communities, the production of extracellular effectors is a common strategy to control the biodiversity by interfering with the growth and/or viability of nearby microbes. One of such effectors relies on the production and release of extracellular D-amino acids which regulate diverse cellular processes such as cell wall biogenesis, biofilm integrity, and spore germination. Non-canonical D-amino acids are mainly produced by broad spectrum racemases (Bsr). Bsr’s promiscuity allows it to generate high concentrations of D-amino acids in environments with variable compositions of L-amino acids. However, it was not clear until recent whether these molecules exhibit divergent functions. Here we review the distinctive biological roles of D-amino acids, their mechanisms of action and their modulatory properties of the biodiversity of complex eco-systems. PMID:29681896

  17. Improving Our Ability to Evaluate Underlying Mechanisms of Behavioral Onset and Other Event Occurrence Outcomes: A Discrete-Time Survival Mediation Model.

    Science.gov (United States)

    Fairchild, Amanda J; Abara, Winston E; Gottschall, Amanda C; Tein, Jenn-Yun; Prinz, Ronald J

    2015-09-01

    The purpose of this article is to introduce and describe a statistical model that researchers can use to evaluate underlying mechanisms of behavioral onset and other event occurrence outcomes. Specifically, the article develops a framework for estimating mediation effects with outcomes measured in discrete-time epochs by integrating the statistical mediation model with discrete-time survival analysis. The methodology has the potential to help strengthen health research by targeting prevention and intervention work more effectively as well as by improving our understanding of discretized periods of risk. The model is applied to an existing longitudinal data set to demonstrate its use, and programming code is provided to facilitate its implementation. © The Author(s) 2013.

  18. Surviving or thriving: quality assurance mechanisms to promote innovation in the development of evidence-based parenting interventions.

    Science.gov (United States)

    Sanders, Matthew R; Kirby, James N

    2015-04-01

    Parenting interventions have the potential to make a significant impact to the prevention and treatment of major social and mental health problems of children. However, parenting interventions fail to do so because program developers pay insufficient attention to the broader ecological context that influences the adoption and implementation of evidence-based interventions. This context includes the professional and scientific community, end users, consumers, and broader sociopolitical environment within which parenting services are delivered. This paper presents an iterative stage model of quality assurance steps to guide ongoing research and development particularly those related to program innovations including theory building, intervention development, pilot testing, efficacy and effectiveness trials, program refinement, dissemination, and planning for implementation and political advocacy. The key challenges associated with each phase of the research and development process are identified. Stronger consumer participation throughout the entire process from initial program design to wider community dissemination is an important, but an often ignored part of the process. Specific quality assurance mechanisms are discussed that increase accountability, professional, and consumer confidence in an intervention and the evidence supporting its efficacy.

  19. Studies on electrochemical hydrodebromination mechanism of 2,5-dibromobenzoic acid on Ag electrode by in situ FTIR spectroscopy

    International Nuclear Information System (INIS)

    Li Meichao; Bao Dandan; Ma Chunan

    2011-01-01

    Research highlights: → Silver is a good catalyst for the hydrodebromination of 2,5-dibromobenzoic acid. → 3-Bromobenzoic acid as main intermediate product. → The finally product is benzoic acid. → In situ FTIR is useful to study the electrochemical hydrodebromination mechanism. - Abstract: Cyclic voltammetry and in situ FTIR were employed to study the electrochemical hydrodebromination (EHB) mechanism of 2,5-dibromobenzoic acid (2,5-DBBA) in NaOH solution. Compared with titanium and graphite electrodes, silver electrode exhibited a high electrocatalytic activity for the hydrodebromination reaction of 2,5-DBBA. On the basis of in situ FTIR data, EHB reaction of 2,5-DBBA on Ag cathode might be represented as a sequence of electron additions and bromine expulsions. Firstly, from potential at approximately -1100 mV, 2,5-DBBA received an electron to form 2,5-DBBA radical anion, which lost a bromine ion in the 2-position to form 3-bromobenzoic acid (3-BBA) free radical. Then the free radical received a proton to give 3-BBA. Finally, 3-BBA further took off another bromine ion to produce benzoic acid free radical and the end product benzoic acid was obtained by receiving another electron and a proton with the potential shifting to more negative values.

  20. Microbial iron management mechanisms in extremely acidic environments: comparative genomics evidence for diversity and versatility

    Directory of Open Access Journals (Sweden)

    Nieto Pamela A

    2008-11-01

    Full Text Available Abstract Background Iron is an essential nutrient but can be toxic at high intracellular concentrations and organisms have evolved tightly regulated mechanisms for iron uptake and homeostasis. Information on iron management mechanisms is available for organisms living at circumneutral pH. However, very little is known about how acidophilic bacteria, especially those used for industrial copper bioleaching, cope with environmental iron loads that can be 1018 times the concentration found in pH neutral environments. This study was motivated by the need to fill this lacuna in knowledge. An understanding of how microorganisms thrive in acidic ecosystems with high iron loads requires a comprehensive investigation of the strategies to acquire iron and to coordinate this acquisition with utilization, storage and oxidation of iron through metal responsive regulation. In silico prediction of iron management genes and Fur regulation was carried out for three Acidithiobacilli: Acidithiobacillus ferrooxidans (iron and sulfur oxidizer A. thiooxidans and A. caldus (sulfur oxidizers that can live between pH 1 and pH 5 and for three strict iron oxidizers of the Leptospirillum genus that live at pH 1 or below. Results Acidithiobacilli have predicted FeoB-like Fe(II and Nramp-like Fe(II-Mn(II transporters. They also have 14 different TonB dependent ferri-siderophore transporters of diverse siderophore affinity, although they do not produce classical siderophores. Instead they have predicted novel mechanisms for dicitrate synthesis and possibly also for phosphate-chelation mediated iron uptake. It is hypothesized that the unexpectedly large number and diversity of Fe(III-uptake systems confers versatility to this group of acidophiles, especially in higher pH environments (pH 4–5 where soluble iron may not be abundant. In contrast, Leptospirilla have only a FtrI-Fet3P-like permease and three TonB dependent ferri-dicitrate siderophore systems. This paucity of iron

  1. Recent Advances in Understanding Amino Acid Sensing Mechanisms that Regulate mTORC1

    Directory of Open Access Journals (Sweden)

    Liufeng Zheng

    2016-09-01

    Full Text Available The mammalian target of rapamycin (mTOR is the central regulator of mammalian cell growth, and is essential for the formation of two structurally and functionally distinct complexes: mTORC1 and mTORC2. mTORC1 can sense multiple cues such as nutrients, energy status, growth factors and hormones to control cell growth and proliferation, angiogenesis, autophagy, and metabolism. As one of the key environmental stimuli, amino acids (AAs, especially leucine, glutamine and arginine, play a crucial role in mTORC1 activation, but where and how AAs are sensed and signal to mTORC1 are not fully understood. Classically, AAs activate mTORC1 by Rag GTPases which recruit mTORC1 to lysosomes, where AA signaling initiates. Plasma membrane transceptor L amino acid transporter 1 (LAT1-4F2hc has dual transporter-receptor function that can sense extracellular AA availability upstream of mTORC1. The lysosomal AA sensors (PAT1 and SLC38A9 and cytoplasmic AA sensors (LRS, Sestrin2 and CASTOR1 also participate in regulating mTORC1 activation. Importantly, AAs can be sensed by plasma membrane receptors, like G protein-coupled receptor (GPCR T1R1/T1R3, and regulate mTORC1 without being transported into the cells. Furthermore, AA-dependent mTORC1 activation also initiates within Golgi, which is regulated by Golgi-localized AA transporter PAT4. This review provides an overview of the research progress of the AA sensing mechanisms that regulate mTORC1 activity.

  2. Short-chain carboxylic acids, a new class of teratogens: studies of potential biochemical mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Coakley, M.E.; Rawlings, S.J.; Brown, N.A.

    1986-12-01

    Certain short-chain carboxylic acids (SCCA) appear to share a common teratogenic potential, although the structural requirements for activity remain obscure. By using a whole rat embryo culture model system, several biochemical processes have been examined, either as potential initial sites of teratogenic action or as early steps in the pathway to malformation. Valproate, methoxyacetate, and butyrate were the prototype SCCA examined. Measurement of (/sup 14/C)glucose utilization and lactate production confirmed that energy production by the early organogenesis embryo is predominantly from glycolysis. While the positive control agent, iodoacetate, caused a significant inhibition of lactate production, none of the SCCA affected this process or glucose utilization at teratogenic concentrations. Pinocytosis by the visceral yolk sac (VYS) was measured by the uptake of (/sup 125/I)polyvinylpyrrolidone. This process ultimately supplies the embryo with amino-acids and is essential for normal development. SCCA induce morphological abnormalities of the VYS in embryo culture. Pinocytosis was slightly reduced by valproate, but not the other SCCA. However, comparison with the action of an antiserum, for which inhibition of pinocytosis is the initial teratogenic insult, suggests that this is not the mechanism for valproate. Incorporation of (/sup 3/H)thymidine into embryo or yolk sac was not affected after 3 hr of SCCA exposure, but there was a marked effect of the positive control, hydroxyurea. This suggests that DNA synthesis is not directly influenced by SCCA. It can be concluded that SCCA do not exert their teratogenic effects by actions on glycolysis; maintenance of cellular acetyl CoA; pinocytosis or DNA synthesis. These observations contrast with preliminary results which suggest significant effects of SCCA on embryonic and yolk sac lipid metabolic pathways.

  3. A transcriptomic computational analysis of mastic oil-treated Lewis lung carcinomas reveals molecular mechanisms targeting tumor cell growth and survival

    Directory of Open Access Journals (Sweden)

    Roussos Charis

    2009-12-01

    Full Text Available Abstract Background Mastic oil from Pistacia lentiscus variation chia, a blend of bioactive terpenes with recognized medicinal properties, has been recently shown to exert anti-tumor growth activity through inhibition of cancer cell proliferation, survival, angiogenesis and inflammatory response. However, no studies have addressed its mechanisms of action at genome-wide gene expression level. Methods To investigate molecular mechanisms triggered by mastic oil, Lewis Lung Carcinoma cells were treated with mastic oil or DMSO and RNA was collected at five distinct time points (3-48 h. Microarray expression profiling was performed using Illumina mouse-6 v1 beadchips, followed by computational analysis. For a number of selected genes, RT-PCR validation was performed in LLC cells as well as in three human cancer cell lines of different origin (A549, HCT116, K562. PTEN specific inhibition by a bisperovanadium compound was applied to validate its contribution to mastic oil-mediated anti-tumor growth effects. Results In this work we demonstrated that exposure of Lewis lung carcinomas to mastic oil caused a time-dependent alteration in the expression of 925 genes. GO analysis associated expression profiles with several biological processes and functions. Among them, modifications on cell cycle/proliferation, survival and NF-κB cascade in conjunction with concomitant regulation of genes encoding for PTEN, E2F7, HMOX1 (up-regulation and NOD1 (down-regulation indicated some important mechanistic links underlying the anti-proliferative, pro-apoptotic and anti-inflammatory effects of mastic oil. The expression profiles of Hmox1, Pten and E2f7 genes were similarly altered by mastic oil in the majority of test cancer cell lines. Inhibition of PTEN partially reversed mastic oil effects on tumor cell growth, indicating a multi-target mechanism of action. Finally, k-means clustering, organized the significant gene list in eight clusters demonstrating a similar

  4. Survival of Unstressed and Acid-, Cold-, and Starvation-Stress-Adapted Listeria monocytogenes in Ham Extract with Hops Beta Acids and Consumer Acceptability of HBA on Ready-to-Eat Ham

    Directory of Open Access Journals (Sweden)

    Li Wang

    2015-01-01

    Full Text Available The efficacy of hops beta acids (HBA against unstressed and stress-adapted Listeria monocytogenes in ham extract and the consumers’ acceptability of HBA on ready-to-eat (RTE hams were investigated. Unstressed or acid-, cold-, or starvation-stress-adapted L. monocytogenes was inoculated (1.3–1.5 log CFU/mL into 10% ham extract, without (control or with HBA (4.44 or 10.0 µg/mL. Survival/growth of the pathogen during storage (7.2°C, 26 days was monitored periodically. Sensory evaluation (30 participants, 9-point hedonic scale was performed with hams dipped into 0.05, 0.11, and 0.23% HBA solution. Ham extracts without HBA supported rapid growth of unstressed and stress-adapted cells with growth rates of 0.39–0.71 log CFU/mL/day and lag phases of 0–3.26 days. HBA inhibited growth of unstressed L. monocytogenes by slowing (P0.05 affect sensory attributes of RTE ham. These results are useful for RTE meat processors to develop operational protocols using HBA to control L. monocytogenes.

  5. Survival of Unstressed and Acid-, Cold-, and Starvation-Stress-Adapted Listeria monocytogenes in Ham Extract with Hops Beta Acids and Consumer Acceptability of HBA on Ready-to-Eat Ham.

    Science.gov (United States)

    Wang, Li; Shen, Cangliang

    2015-01-01

    The efficacy of hops beta acids (HBA) against unstressed and stress-adapted Listeria monocytogenes in ham extract and the consumers' acceptability of HBA on ready-to-eat (RTE) hams were investigated. Unstressed or acid-, cold-, or starvation-stress-adapted L. monocytogenes was inoculated (1.3-1.5 log CFU/mL) into 10% ham extract, without (control) or with HBA (4.44 or 10.0 µg/mL). Survival/growth of the pathogen during storage (7.2 °C, 26 days) was monitored periodically. Sensory evaluation (30 participants, 9-point hedonic scale) was performed with hams dipped into 0.05, 0.11, and 0.23% HBA solution. Ham extracts without HBA supported rapid growth of unstressed and stress-adapted cells with growth rates of 0.39-0.71 log CFU/mL/day and lag phases of 0-3.26 days. HBA inhibited growth of unstressed L. monocytogenes by slowing (P 0.05) affect sensory attributes of RTE ham. These results are useful for RTE meat processors to develop operational protocols using HBA to control L. monocytogenes.

  6. The effect of two novel amino acid-coated magnetic nanoparticles on survival in vascular endothelial cells, bone marrow stromal cells, and macrophages

    Science.gov (United States)

    Wu, Qinghua; Meng, Ning; Zhang, Yanru; Han, Lei; Su, Le; Zhao, Jing; Zhang, Shangli; Zhang, Yun; Zhao, Baoxiang; Miao, Junying

    2014-09-01

    Magnetic nanoparticles (MNPs) have been popularly used in many fields. Recently, many kinds of MNPs are modified as new absorbents, which have attracted considerable attention and are promising to be applied in waste water. In our previous study, we synthesized two novel MNPs surface-coated with glycine or lysine, which could efficiently remove many anionic and cationic dyes under severe conditions. It should be considered that MNP residues in water may exert some side effects on human health. In the present study, we evaluated the potential nanotoxicity of MNPs in human endothelial cells, macrophages, and rat bone marrow stromal cells. The results showed that the two kinds of nanoparticles were consistently absorbed into the cell cytoplasm. The concentration of MNPs@Gly that could distinctly decrease survival was 15 μg/ml in human umbilical vascular endothelial cells (HUVECs) or bone marrow stromal cells (BMSCs) and 10 μg/ml in macrophages. While the concentration of MNPs@Lys that obviously reduced viability was 15 μg/ml in HUVECs or macrophages and 50 μg/ml in BMSCs. Furthermore, cell nucleus staining and cell integrity assay indicated that the nanoparticles induced cell apoptosis, but not necrosis even at a high concentration. Altogether, these data suggest that the amino acid-coated magnetic nanoparticles exert relatively high cytotoxicity. By contrast, lysine-coated magnetic nanoparticles are more secure than glycine-coated magnetic nanoparticles.

  7. Weibull Statistical Analysis on the Mechanical Properties of SiC by Immersion in Acidic and Alkaline Solutions

    International Nuclear Information System (INIS)

    Ahn, Seok-Hwan; Jeong, Sang-Cheol; Nam, Ki-Woo

    2016-01-01

    A Weibull statistical analysis of the mechanical properties of SiC ceramics was carried out by immersion in acidic and alkaline solutions. The heat treatment was carried out at 1373 K. The corrosion of SiC was carried out in acidic and alkaline solutions under KSL1607. The bending strength of corroded crack-healed specimens decreased 47 % and 70 % compared to those of uncorroded specimens in acidic and alkaline solutions, respectively. The corrosion of SiC ceramics is faster in alkaline solution than in acid solution. The scale and shape parameters were evaluated for the as-received and corroded materials, respectively. The shape parameter of the as-received material corroded in acidic and alkaline solutions was significantly more apparent in the acidic solution. Further, the heat-treated material was large in acidic solution but small in alkaline solution. The shape parameters of the as-received and heat-treated materials were smaller in both acidic and alkaline solutions

  8. Water Susceptibility and Mechanical Properties of Thermoplastic Starch–Pectin Blends Reactively Extruded with Edible Citric Acid

    OpenAIRE

    Da Róz,Alessandra Luzia; Veiga-Santos,Pricila; Ferreira,Adriane Medeiros; Antunes,Thaís Cristina Ribeiro; Leite,Fabio de Lima; Yamaji,Fabio Minoru; Carvalho,Antonio José Felix de

    2016-01-01

    Pectin and starch are edible, non-toxic, biodegradable and obtained from renewable sources. Also, have the benefit to be easily cross-linked producing hydrogels. Reactive extrusion with edible citric acid and cross linking interactions was evaluated on extruded thermoplastic in natura and cationic starch-pectin blends. Materials water susceptibility and mechanical properties were characterised. Reactive extrusion decreased (up to 75% in natura starch) mechanical properties. Also have decrease...

  9. The Mechanism of Rh-Catalyzed Transformation of Fatty Acids to Linear Alpha olefins

    Directory of Open Access Journals (Sweden)

    Sondre H. Hopen Eliasson

    2017-12-01

    Full Text Available Linear alpha olefins (LAOs are key commodity chemicals and petrochemical intermediates that are currently produced from fossil resources. Fatty acids are the obvious renewable starting material for LAOs, which can be obtained via transition-metal-catalyzed decarbonylative dehydration. However, even the best catalysts that have been obtained to date, which are based on palladium, are not active and stable enough for industrial use. To provide insight for design of better catalysts, we here present the first computationally derived mechanism for another attractive transition-metal for this reaction, rhodium. By comparing the calculated mechanisms and free energy profiles for the two metals, Pd and Rh, we single out important factors for a facile, low-barrier reaction and for a stable catalyst. While the olefin formation is rate limiting for both of the metals, the rate-determining intermediate for Rh is, in contrast to Pd, the starting complex, (PPh32Rh(COCl. This complex largely draws its stability from the strength of the Rh(I–CO bond. CO is a much less suitable ligand for the high-oxidation state Rh(III. However, for steric reasons, rhodium dissociates a bulkier triphenylphosphine and keeps the carbonyl during the oxidative addition, which is less favorable than for Pd. When compared to Pd, which dissociates two phosphine ligands at the start of the reaction, the catalytic activity of Rh also appears to be hampered by its preference for high coordination numbers. The remaining ancillary ligands leave less space for the metal to mediate the reaction.

  10. Physiological Mechanism of Salicylic Acid for Alleviation of Salt Stress in Rice

    Directory of Open Access Journals (Sweden)

    D. Jini

    2017-03-01

    Full Text Available Soil salinity is one of the most important problems of crop production in estuarine and coastal zones. Improvement in salt tolerance of major food crops is an important way for the economic utilization of coastal zones. This study proved that the application of salicylic acid (SA improved the growth and yield under salt stress conditions and investigated its physiological mechanisms for salt tolerance. The investigation on the effect of SA for salt tolerance during germination showed that the decreased rates of germination and growth (in terms of shoot and root lengths by the salt stress were significantly increased by the SA application (SA + NaCl. The treatment of SA to the high and low saline soils enhanced the growth, yield and nutrient values of rice. The effects of SA on Na+, K+ and Cl– ionic accumulation were traced under salt stress condition by inductively coupled plasma optical emission spectrometry and ion chromatography. It was revealed that the increased accumulation of Na+ and Clˉ ions by the salt stress were reduced by SA application. An increased concentration of endogenous SA level was detected from the SA-treated rice varieties (ASD16 and BR26 by liquid chromatography electrospray Ionization-tandem mass spectrometry. The activities of antioxidant enzymes such as superoxide dismutase, catalase and peroxidase were increased by salt stress whereas decreased by the SA application. The study proved that the application of SA could alleviate the adverse effects of salt stress by the regulation of physiological mechanism in rice plants. In spite of salt stress, it can be applied to the coastal and estuarine regions to increase the rice production.

  11. Cellular mechanisms involved in CO(2) and acid signaling in chemosensitive neurons.

    Science.gov (United States)

    Putnam, Robert W; Filosa, Jessica A; Ritucci, Nicola A

    2004-12-01

    An increase in CO(2)/H(+) is a major stimulus for increased ventilation and is sensed by specialized brain stem neurons called central chemosensitive neurons. These neurons appear to be spread among numerous brain stem regions, and neurons from different regions have different levels of chemosensitivity. Early studies implicated changes of pH as playing a role in chemosensitive signaling, most likely by inhibiting a K(+) channel, depolarizing chemosensitive neurons, and thereby increasing their firing rate. Considerable progress has been made over the past decade in understanding the cellular mechanisms of chemosensitive signaling using reduced preparations. Recent evidence has pointed to an important role of changes of intracellular pH in the response of central chemosensitive neurons to increased CO(2)/H(+) levels. The signaling mechanisms for chemosensitivity may also involve changes of extracellular pH, intracellular Ca(2+), gap junctions, oxidative stress, glial cells, bicarbonate, CO(2), and neurotransmitters. The normal target for these signals is generally believed to be a K(+) channel, although it is likely that many K(+) channels as well as Ca(2+) channels are involved as targets of chemosensitive signals. The results of studies of cellular signaling in central chemosensitive neurons are compared with results in other CO(2)- and/or H(+)-sensitive cells, including peripheral chemoreceptors (carotid body glomus cells), invertebrate central chemoreceptors, avian intrapulmonary chemoreceptors, acid-sensitive taste receptor cells on the tongue, and pain-sensitive nociceptors. A multiple factors model is proposed for central chemosensitive neurons in which multiple signals that affect multiple ion channel targets result in the final neuronal response to changes in CO(2)/H(+).

  12. Effect of Enriched Artemia sp. by EPA (Eicosapentaenoic Acid; C20:5n-3 and DHA (Docosahexaenoic Acid; C22:6n-3 on Survival Rate of Swimming Crab Portunus pelagicus

    Directory of Open Access Journals (Sweden)

    M. Agus Suprayudi

    2007-07-01

    Full Text Available Nutrient content of natural food is one of the main factors for determining the successful of marine fish fry production.  EPA (Eicosapentaenoic Acid and DHA (Docosahexaenoic Acid are two essential fatty acids for marine fish larvae.   Low levels of EPA and DHA content in natural food is major problem in marine fish larval production.  Rotifers fed by Nannochloropsis contained EPA about 0.94%-1.46% and DHA was limited, while in Artemia was 0.27%-0.39% EPA and DHA was undetected (Suprayudi et al., 2002a.  Feeding on supplemented Artemia with EPA 28G and DHA 70G in ratio of 1:1 could not significantly improved its survival rate and larval development time, while growth by length and carapas width at first crab were higher  than  that of fed with unenriched Artemia. Keywords: EPA, DHA, Artemia, swimming crab, Portunus pelagicus   ABSTRAK Kandungan nutrisi dalam pakan alami merupakan salah satu faktor utama yang menentukan keberhasilan produksi benih spesies akuatik laut.  EPA (asam ekosapentanat dan DHA (asam dokosaheksanat merupakan 2 asam lemak esensil bagi larva ikan laut.  Kandungan EPA dan DHA yang rendah pada pakan alami merupakan masalah utama dalam produksi larva ikan laut.  Rotifer yang diberi pakan Nannochloropsis mengandung EPA 0,94%-1,46% dan DHA dengan jumlah yang sangat kecil, sementara Artemia EPA mengandung 0,27%-0,39% dan DHA tidak terdeteksi (Suprayudi et al., 2002a. Pemberian Artemia yang diperkaya dengan EPA 28G dan DHA 70G dengan perbandingan 1:1 tidak memberikan hasil yang signifikan pada tingkat kelangsungan hidup dan waktu perkembangan larva rajungan, sementara pertumbuhan panjang dan lebar karapas lebih baik pada crab 1 dibandingkan dengan yang diberi Artemia tidak diperkaya. Kata kunci: EPA, DHA, Artemia, rajungan, Portunus pelagicus

  13. Influence of various acids on the physico–mechanical properties of ...

    Indian Academy of Sciences (India)

    After 28 days of hardening, the samples were immersed into four different concentrations of hydrochloric, nitric and sulfuric acid solutions for a period of 120 days. The changes in weight loss and compressive strength values for each acid solution within the test period were recorded. The acid resistance of mortars made ...

  14. Kinetics and mechanism of the oxidation of some neutral and acidic ...

    Indian Academy of Sciences (India)

    The oxidation of eleven amino acids by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid results in the formation of the corresponding carbonyl compounds and ammonia. The reaction is first order with respect to TBATB. Michaelis-Menten type kinetics is observed with some of the amino acids while others ...

  15. Kinetics and mechanism of the oxidation of formic and oxalic acids ...

    Indian Academy of Sciences (India)

    The oxidation of formic and oxalic acids by benzyltrimethylammonium dichloroiodate (BTMACI), in the presence of zinc chloride, leads to the formation of carbon dioxide. The reaction is first order with respect to BTMACI, zinc chloride and organic acid. Oxidation of deuteriated formic acid indicates the presence of a kinetic ...

  16. Kinetics and mechanism of the oxidation of some neutral and acidic ...

    Indian Academy of Sciences (India)

    Unknown

    recrystallization. Stoichiometry, with an excess of amino acid could not be studied because of the difficulty in determin- ing the concentration of amino acids. Stoichiometric determination with an excess of TBATB showed that two moles of TBATB were consumed per mole of the amino acid. This is because aldehydes, the.

  17. The net acid extruders NHE1, NBCn1 and MCT4 promote mammary tumor growth through distinct but overlapping mechanisms

    DEFF Research Database (Denmark)

    Andersen, Anne Poder; Samsøe-Petersen, Jacob; Oernbo, Eva Kjer

    2018-01-01

    in soft agar, KD of NHE1 did not have these effects. Moreover, only MCT4 KD reduced Akt kinase activity, PARP and CD147 expression and cell motility. This work reveals that different types of net acid extruding transporters, NHE1, NBCn1 and MCT4, are frequently expressed in patient mammary tumor tissue......High metabolic and proliferative rates in cancer cells lead to production of large amounts of H+ and CO2 , and as a result, net acid extruding transporters are essential for the function and survival of cancer cells. We assessed protein expression of the Na+ /H+ exchanger NHE1, the Na+ - HCO3......- cotransporter NBCn1, and the lactate-H+ cotransporters MCT1 and -4 by immunohistochemical analysis of a large cohort of breast cancer samples. We found robust expression of these transporters in 20, 10, 4 and 11% of samples, respectively. NHE1 and NBCn1 expression both correlated positively with progesterone...

  18. Study on the Mechanism of Interaction between Phthalate Acid Esters and Bovine Hemoglobin.

    Science.gov (United States)

    Chi, Zhenxing; Zhao, Jing; You, Hong; Wang, Mingjing

    2016-08-03

    Phthalate acid esters (PAEs) are widely used in plastic products as a series of chemical softeners. However, PAEs, which now exist in many environmental media such as the atmosphere, water, and soil, have been shown to be environmental endocrine disruptors. Hemoglobin is a functional protein that carries oxygen in the red blood cells of animals. This study aims at revealing the interactions between bovine hemoglobin (BHb) and PAEs using spectroscopic and molecular modeling methods. The results indicate that the selected representative PAEs-dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP)-can interact with BHb to form BHb-PAE complexes with one binding site, mainly relying on hydrophobic forces, with the affinity order DMP > DEP > DBP, opposite to the order of side-chain length. The binding of PAEs can cause conformational and micro-environmental changes in BHb, which may affect the physiological functions of Hb. Furthermore, molecular docking was applied to define the specific binding sites, the results of which show that all the three PAEs can bind into the central cavity of BHb. The study contributes to expound the toxic mechanism of PAEs in vivo from the point of hematological toxicology.

  19. Mechanical Properties of Poly(lactic acid Sheet Reinforced with Microfibrillated Cellulose from Corn Cobs

    Directory of Open Access Journals (Sweden)

    Deejam Prapatsorn

    2015-01-01

    Full Text Available In this study, cellulose was extracted from corn cobs by successive hot NaOH solution and followed by H2O2 bleaching. XRD pattern show characteristic peak of Cellulose I. Microfibrillated cellulose (MFC was successfully prepared by dissolving the extracted cellulose in NaOH/urea solution, shearing in a homogenizer and finally by freezing and thawing. To improve strength of MFC, MFC was physically crosslinked using PVA by freezing and thawing. The crosslinked MFC/PVA was added to poly(lactic acid (PLA to improve its mechanical properties. The non-crosslinked MFC/PVA was also prepared by only stirring the solution without freezing and thawing. MFC/PVA reinforced PLA films with various ratios of PLA and MFC/PVA at100:0, 99:1, 97:3 and 95:5were prepared through a solution casting method. Tensile strength and elongation at breakof PLA films increased with the addition of physically crosslinked MFC/PVA at 1%wt, whereas, the addition of non-crosslinked MFC/PVA decreased elongation at break. Crosslinking of MFC/PVA can improve tensile strength of PLA.It can render better tensile strength than that of non-crosslinked MFC/PVA. However, when MFC/PVA contents increase, tensile strength of PLA fims reinforced with non-crosslinked and crosslinked MFC/PVA decreased. Morphology of fracture surfaces reveals good dispersion and adhesion between 1% crosslinked MFC/PVA and PLA matrix.

  20. Morphology, thermal, mechanical, and barrier properties of graphene oxide/poly(lactic acid) nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Woo; Choi, Hyun Muk [Kyonggi University, Suwon (Korea, Republic of)

    2016-01-15

    To improve the physical and gas barrier properties of biodegradable poly(lactic acid) (PLA) film, two graphene nanosheets of highly functionalized graphene oxide (0.3 wt% to 0.7 wt%) and low-functionalized graphene oxide (0.5 wt%) were incorporated into PLA resin via solution blending method. Subsequently, we investigated the effects of material parameters such as loading level and degree of functionalization for the graphene nanosheets on the morphology and properties of the resultant nanocomposites. The highly functionalized graphene oxide (GO) caused more exfoliation and homogeneous dispersion in PLA matrix as well as more sustainable suspensions in THF, compared to low-functionalized graphene oxide (LFGO). When loaded with GO from 0.3 wt% to 0.7 wt%, the glass transition temperature, degree of crystallinity, tensile strength and modulus increased steadily. The GO gave rise to more pronounced effect in the thermal and mechanical reinforcement, relative to LFGO. In addition, the preparation of fairly transparent PLA-based nanocomposite film with noticeably improved barrier performance achieved only when incorporated with GO up to 0.7wt%. As a result, GO may be more compatible with hydrophilic PLA resin, compared to LFGO, resulting in more prominent enhancement of nanocomposites properties.

  1. A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

    KAUST Repository

    Melcher, Karsten

    2009-12-03

    Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved ?-loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling. © 2009 Macmillan Publishers Limited. All rights reserved.

  2. Mechanism and stereoselectivity of HDAC I inhibition by (R)-9-hydroxystearic acid in colon cancer.

    Science.gov (United States)

    Parolin, Carola; Calonghi, Natalia; Presta, Enrica; Boga, Carla; Caruana, Paolo; Naldi, Marina; Andrisano, Vincenza; Masotti, Lanfranco; Sartor, Giorgio

    2012-10-01

    9-Hydroxystearic acid (9-HSA) belongs to the endogenous lipid peroxidation by-products that decrease in tumors, causing as a consequence the loss of one of the control mechanisms on cell division. It acts as a histone deacetylase (HDAC, E.C 3.5.1.98) inhibitor, and the interaction of the two enantiomers of 9-HSA with the catalytic site of the enzyme, investigated by using a molecular modelling approach, has been reported to be different. In this work we tested out this prediction by synthesizing the two enantiomers (R)-9-HSA (R-9) and (S)-9-HSA (S-9) starting from the natural source methyl dimorphecolate obtained from Dimorphotheca sinuata seeds and investigating their biological activity in HT29 cells. Both enantiomers inhibit the enzymatic activity of HDAC1, HDAC2 and HDAC3, R-9 being more active; R-9 and S-9 inhibitory effect induces an increase in histone H4 acetylation. We also demonstrate that the antiproliferative effect brought about by R-9 is more pronounced as well as we observe increase of p21 transcription and protein content, while the expression of cyclin D1 is decreased. Starting from these observations it can be hypothesized that the interaction of R-9 with HDAC1 induce conformational changes in the enzyme causing loss of its interaction with other proteins, like cyclin D1 itself. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Mechanical, Thermal and Morphological Properties of Poly(lactic acid/Epoxidized Palm Olein Blend

    Directory of Open Access Journals (Sweden)

    Hazimah Abu Hassan

    2012-10-01

    Full Text Available Poly(lactic acid (PLA is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt% through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered.

  4. Biosynthesis of Polyunsaturated Fatty Acids in Marine Invertebrates: Recent Advances in Molecular Mechanisms

    Science.gov (United States)

    Monroig, Óscar; Tocher, Douglas R.; Navarro, Juan C.

    2013-01-01

    Virtually all polyunsaturated fatty acids (PUFA) originate from primary producers but can be modified by bioconversions as they pass up the food chain in a process termed trophic upgrading. Therefore, although the main primary producers of PUFA in the marine environment are microalgae, higher trophic levels have metabolic pathways that can produce novel and unique PUFA. However, little is known about the pathways of PUFA biosynthesis and metabolism in the levels between primary producers and fish that are largely filled by invertebrates. It has become increasingly apparent that, in addition to trophic upgrading, de novo synthesis of PUFA is possible in some lower animals. The unequivocal identification of PUFA biosynthetic pathways in many invertebrates is complicated by the presence of other organisms within them. These organisms include bacteria and algae with PUFA biosynthesis pathways, and range from intestinal flora to symbiotic relationships that can involve PUFA translocation to host organisms. This emphasizes the importance of studying biosynthetic pathways at a molecular level, and the continual expansion of genomic resources and advances in molecular analysis is facilitating this. The present paper highlights recent research into the molecular and biochemical mechanisms of PUFA biosynthesis in marine invertebrates, particularly focusing on cephalopod molluscs. PMID:24152561

  5. Adaptive thermogenesis by dietary n-3 polyunsaturated fatty acids: Emerging evidence and mechanisms.

    Science.gov (United States)

    Fan, Rong; Koehler, Karsten; Chung, Soonkyu

    2018-04-19

    Brown/beige fat plays a crucial role in maintaining energy homeostasis through non-shivering thermogenesis in response to cold temperature and excess nutrition (adaptive thermogenesis). Although numerous molecular and genetic regulators have been identified, relatively little information is available regarding thermogenic dietary molecules. Recently, a growing body of evidence suggests that high consumption of n-3 polyunsaturated fatty acids (PUFA) or activation of GPR120, a membrane receptor of n-3 PUFA, stimulate adaptive thermogenesis. In this review, we summarize the emerging evidence that n-3 PUFA promote brown/beige fat formation and highlight the potential mechanisms whereby n-3 PUFA require GPR120 as a signaling platform or act independently. Human clinical trials are revisited in the context of energy expenditure. Additionally, we explore some future perspective that n-3 PUFA intake might be a useful strategy to boost or sustain metabolic activities of brown/beige fat at different lifecycle stages of pregnancy and senescence. Given that a high ratio of n-6/n-3 PUFA intake is associated with the development of obesity and type 2 diabetes, understanding the impact of n-6/n-3 ratio on energy expenditure and adaptive thermogenesis will inform the implementation of a novel nutritional strategy for preventing obesity. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Structural Analysis and Mechanical Characterization of Hyaluronic Acid-Based Doubly Cross-Linked Networks.

    Science.gov (United States)

    Jha, Amit K; Hule, Rohan A; Jiao, Tong; Teller, Sean S; Clifton, Rodney J; Duncan, Randall L; Pochan, Darrin J; Jia, Xinqiao

    2009-01-01

    We have created a new class of hyaluronic acid (HA)-based hydrogel materials with HA hydrogel particles (HGPs) embedded in and covalently cross-linked to a secondary network. HA HGPs with an average diameter of ∼900 nm and narrow particle size distribution were synthesized using a refined reverse micelle polymerization technique. The average mesh size of the HGPs was estimated to be approximately 5.5 to 7.0 nm by a protein uptake experiment. Sodium periodate oxidation not only introduced aldehyde groups to the particles but also reduced the average particle size. The aldehyde groups generated were used as reactive handles for subsequent cross-linking with an HA derivative containing hydrazide groups. The resulting macroscopic gels contain two distinct hierarchical networks (doubly cross-linked networks, DXNs): one within individual particles and another among different particles. Bulk gels (BGs) formed by direct mixing of HA derivatives with mutually reactive groups were included for comparison. The hydrogel microstructures were collectively characterized by microscopy and neutron scattering techniques. Their viscoelasticity was quantified at low frequencies (0.1-10 Hz) using a controlled stress rheometer and at high frequencies (up to 200 Hz) with a home-built torsional wave apparatus. Both BGs and DXNs are stable elastic gels that become stiffer at higher frequencies. The HA-based DXN offers unique structural hierarchy and mechanical properties that are suitable for soft tissue regeneration.

  7. A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

    Energy Technology Data Exchange (ETDEWEB)

    Melcher, Karsten; Ng, Ley-Moy; Zhou, X Edward; Soon, Fen-Fen; Xu, Yong; Suino-Powell, Kelly M; Park, Sang-Youl; Weiner, Joshua J; Fujii, Hiroaki; Chinnusamy, Viswanathan; Kovach, Amanda; Li, Jun; Wang, Yonghong; Li, Jiayang; Peterson, Francis C; Jensen, Davin R; Yong, Eu-Leong; Volkman, Brian F; Cutler, Sean R; Zhu, Jian-Kang; Xu, H Eric; (NU Sinapore); (Van Andel); (MCW); (UCR); (Chinese Aca. Sci.)

    2010-01-12

    Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved β-loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling.

  8. Potential Mechanism of Action of meso-Dihydroguaiaretic Acid on Mycobacterium tuberculosis H37Rv

    Directory of Open Access Journals (Sweden)

    Aldo F. Clemente-Soto

    2014-12-01

    Full Text Available The isolation and characterization of the lignan meso-dihydroguaiaretic acid (MDGA from Larrea tridentata and its activity against Mycobacterial tuberculosis has been demonstrated, but no information regarding its mechanism of action has been documented. Therefore, in this study we carry out the gene expression from total RNA obtained from M. tuberculosis H37Rv treated with MDGA using microarray technology, which was validated by quantitative real time polymerase chain reaction. Results showed that the alpha subunit of coenzyme A transferase of M. tuberculosis H37Rv is present in both geraniol and 1-and 2-methylnaphthalene degradation pathways, which are targeted by MDGA. This assumption was supported by molecular docking which showed stable interaction between MDGA with the active site of the enzyme. We propose that inhibition of coenzyme A transferase of M. tuberculosis H37Rv results in the accumulation of geraniol and 1-and 2-methylnaphtalene inside bacteria, causing membrane destabilization and death of the pathogen. The natural product MDGA is thus an attractive template to develop new anti-tuberculosis drugs, because its target is different from those of known anti-tubercular agents.

  9. Mechanism of the OH radical scavenging activity of nordihydroguaiaretic acid: a combined theoretical and experimental study.

    Science.gov (United States)

    Galano, Annia; Macías-Ruvalcaba, Norma A; Medina Campos, Omar Noel; Pedraza-Chaverri, José

    2010-05-20

    The antioxidant nordihydroguaiaretic acid (NDGA) is a plant phenolic lignan originally isolated from the creosote bush (Larrea tridentata). It has been shown that NDGA scavenges efficiently hydroxyl radicals ((*)OH). In the present paper the mechanism by which NDGA scavenges (*)OH is addressed performing a combined experimental and theoretical investigation. We found that NDGA protects, in a concentration-dependent way, bovine serum albumin and DNA from the damage induced by (*)OH generated by the Fenton reaction. In addition, the NDGA + (*)OH reaction is predicted to be diffusion-controlled. The first step of this reaction is proposed to occur mainly by a sequential electron proton transfer from NDGA to (*)OH generating a neutral radical of NDGA, which after a second oxidation step gives a diradical that after a cascade sequential complex reaction produces a cyclic compound. This cyclic product is predicted to have a UV-vis spectrum very similar to that of NDGA, making its identification by this technique very difficult. The electrochemical studies performed in water support the formation of a cyclic compound (C2) as the main product of the reaction. It is concluded that NDGA can scavenge at least two (*)OH.

  10. Mechanical properties of poly(N-isopropylacrylamide-Co-itaconic acid) hydrogels

    International Nuclear Information System (INIS)

    Valderruten, N. E.; Quintana, J. R.; Katime, I.

    2001-01-01

    It is well known that polymers of N-isopropylacrylamide (NIPA) show lower critical solution temperature (LCST) behavior in water and its gels have a volume phase transition at about 34 degree centigree in water. In this study, we reported the polymerization of NIPA in the presence of N,N methylenebisacrylamide (BIS). Poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-itaconic acid) hydrogels were obtained by swelling the resultant solid xerogels to equilibrium in water. The effects of monomer composition and concentration of added cross-linking agent on the swelling behavior and mechanical properties of these hydrogels at 22 and 37 degree centigree were investigated, the latter involving measurements of shear in a DMTA system. The storage moduli at 22 degree centigree lay within the range 9.08-5.08 KPa. At a fixed BIS concentration, an increase from 22 to 37 degree centigree resulted in an increase in the shear moduli and the effective crosslinking density (v e ) and a decrease in the interaction parameter hydrogel/water, χ. (Author) 6 refs

  11. Morphology, thermal, mechanical, and barrier properties of graphene oxide/poly(lactic acid) nanocomposite films

    International Nuclear Information System (INIS)

    Kim, Seong Woo; Choi, Hyun Muk

    2016-01-01

    To improve the physical and gas barrier properties of biodegradable poly(lactic acid) (PLA) film, two graphene nanosheets of highly functionalized graphene oxide (0.3 wt% to 0.7 wt%) and low-functionalized graphene oxide (0.5 wt%) were incorporated into PLA resin via solution blending method. Subsequently, we investigated the effects of material parameters such as loading level and degree of functionalization for the graphene nanosheets on the morphology and properties of the resultant nanocomposites. The highly functionalized graphene oxide (GO) caused more exfoliation and homogeneous dispersion in PLA matrix as well as more sustainable suspensions in THF, compared to low-functionalized graphene oxide (LFGO). When loaded with GO from 0.3 wt% to 0.7 wt%, the glass transition temperature, degree of crystallinity, tensile strength and modulus increased steadily. The GO gave rise to more pronounced effect in the thermal and mechanical reinforcement, relative to LFGO. In addition, the preparation of fairly transparent PLA-based nanocomposite film with noticeably improved barrier performance achieved only when incorporated with GO up to 0.7wt%. As a result, GO may be more compatible with hydrophilic PLA resin, compared to LFGO, resulting in more prominent enhancement of nanocomposites properties.

  12. Poly(vinyl alcohol)-Tannic Acid Hydrogels with Excellent Mechanical Properties and Shape Memory Behaviors.

    Science.gov (United States)

    Chen, Ya-Nan; Peng, Lufang; Liu, Tianqi; Wang, Yaxin; Shi, Shengjie; Wang, Huiliang

    2016-10-12

    Shape memory hydrogels have promising applications in a wide variety of fields. Here we report the facile fabrication of a novel type of shape memory hydrogels physically cross-linked with both stronger and weaker hydrogen bonding (H-bonding). Strong multiple H-bonding formed between poly(vinyl alcohol) (PVA) and tannic acid (TA) leads to their coagulation when they are physically mixed at an elevated temperature and easy gelation at room temperature. The amorphous structure and strong H-bonding endow the PVA-TA hydrogels with excellent mechanical properties, as indicated by their high tensile strengths (up to 2.88 MPa) and high elongations (up to 1100%). The stronger H-bonding between PVA and TA functions as the "permanent" cross-link and the weaker H-bonding between PVA chains as the "temporary" cross-link. The reversible breakage and formation of the weaker H-bonding imparts the PVA-TA hydrogels with excellent temperature-responsive shape memory. Wet and dried hydrogel samples with a deformed or elongated shape can recover to their original shapes when immersed in 60 °C water in a few seconds or at 125 °C in about 2.5 min, respectively.

  13. Protein degradation mechanisms modulate abscisic acid signaling and responses during abiotic stress.

    Science.gov (United States)

    Jurkiewicz, Pawel; Batoko, Henri

    2018-02-01

    Abiotic stresses such as salinity, drought, high temperature or freezing can be perceived, in part, as a transient or permanent hyperosmotic stress by the plant cell. As sessile organisms, the detrimental effects of these environmental insults limit plants productivity but also their geographical distribution. Sensing and signaling events that detect the hyperosmotic (or simply osmotic) stress involve the cellular increase of active abscisic acid (ABA). The stress phytohormone ABA regulates fundamental growth and developmental processes in the plant by marshalling metabolic and gene-expression reprogramming. Among the ABA-responsive genes, some are strictly ABA-dependent in that their expression is almost undetectable in absence of elevated levels of cellular ABA, thus their physiological role may be required only transiently. In addition, ABA-dependent modulation of some of the signaling effectors can be irreversible. In this review, without any pretention to being exhaustive, we use specific examples to illustrate how mechanistically conserved eukaryotic cell proteolytic pathways affect ABA-dependent signaling. We describe how defined proteolysis mechanisms in the plant cell, including Regulated Intramembrane Proteolysis (RIP), the Ubiquitin 26S Proteasomal System (UPS), the endocytic and autophagy pathways, contribute to regulate the spatiotemporal level and activity of PP2Cs (protein phosphatases 2C), and how an intriguing ABA-induced protein, the plant Translocator protein (TSPO), is targeted for degradation. Degradation of regulatory or effector molecules modulates or desensitizes ABA-dependent signaling and reestablishes cellular homeostasis. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Early differential cell death and survival mechanisms initiate and contribute to the development of OPIDN: A study of molecular, cellular, and anatomical parameters

    International Nuclear Information System (INIS)

    Damodaran, T.V.; Attia, M.K.; Abou-Donia, M.B.

    2011-01-01

    Organophosphorus-ester induced delayed neurotoxicity (OPIDN) is a neurodegenerative disorder characterized by ataxia progressing to paralysis with a concomitant central and peripheral, distal axonapathy. Diisopropylphosphorofluoridate (DFP) produces OPIDN in the chicken that results in mild ataxia in 7–14 days and severe paralysis as the disease progresses with a single dose. White leghorn layer hens were treated with DFP (1.7 mg/kg, sc) after prophylactic treatment with atropine (1 mg/kg, sc) in normal saline and eserine (1 mg/kg, sc) in dimethyl sulfoxide. Control groups were treated with vehicle propylene glycol (0.1 ml/kg, sc), atropine in normal saline and eserine in dimethyl sulfoxide. The hens were euthanized at different time points such as 1, 2, 5, 10 and 20 days, and the tissues from cerebrum, midbrain, cerebellum, brainstem and spinal cord were quickly dissected and frozen for mRNA (northern) studies. Northern blots were probed with BCL2, GADD45, beta actin, and 28S RNA to investigate their expression pattern. Another set of hens was treated for a series of time points and perfused with phosphate buffered saline and fixative for histological studies. Various staining protocols such as Hematoxylin and Eosin (H and E); Sevier-Munger; Cresyl echt Violet for Nissl substance; and Gallocynin stain for Nissl granules were used to assess various patterns of cell death and degenerative changes. Complex cell death mechanisms may be involved in the neuronal and axonal degeneration. These data indicate altered and differential mRNA expressions of BCL2 (anti apoptotic gene) and GADD45 (DNA damage inducible gene) in various tissues. Increased cell death and other degenerative changes noted in the susceptible regions (spinal cord and cerebellum) than the resistant region (cerebrum), may indicate complex molecular pathways via altered BCL2 and GADD45 gene expression, causing the homeostatic imbalance between cell survival and cell death mechanisms. Semi quantitative

  15. Early differential cell death and survival mechanisms initiate and contribute to the development of OPIDN: A study of molecular, cellular, and anatomical parameters

    Energy Technology Data Exchange (ETDEWEB)

    Damodaran, T.V., E-mail: tdamodar@nccu.edu [Dept of Medicine, Duke University Medical Center, Durham, NC (United States); Pharmacology and Cancer biology, Duke University Medical Center, Durham, NC (United States); Dept of Biology, North Carolina Central University, Durham, NC 27707 (United States); Attia, M.K. [Pharmacology and Cancer biology, Duke University Medical Center, Durham, NC (United States); Abou-Donia, M.B., E-mail: donia@mc.duke.edu [Pharmacology and Cancer biology, Duke University Medical Center, Durham, NC (United States)

    2011-11-15

    Organophosphorus-ester induced delayed neurotoxicity (OPIDN) is a neurodegenerative disorder characterized by ataxia progressing to paralysis with a concomitant central and peripheral, distal axonapathy. Diisopropylphosphorofluoridate (DFP) produces OPIDN in the chicken that results in mild ataxia in 7-14 days and severe paralysis as the disease progresses with a single dose. White leghorn layer hens were treated with DFP (1.7 mg/kg, sc) after prophylactic treatment with atropine (1 mg/kg, sc) in normal saline and eserine (1 mg/kg, sc) in dimethyl sulfoxide. Control groups were treated with vehicle propylene glycol (0.1 ml/kg, sc), atropine in normal saline and eserine in dimethyl sulfoxide. The hens were euthanized at different time points such as 1, 2, 5, 10 and 20 days, and the tissues from cerebrum, midbrain, cerebellum, brainstem and spinal cord were quickly dissected and frozen for mRNA (northern) studies. Northern blots were probed with BCL2, GADD45, beta actin, and 28S RNA to investigate their expression pattern. Another set of hens was treated for a series of time points and perfused with phosphate buffered saline and fixative for histological studies. Various staining protocols such as Hematoxylin and Eosin (H and E); Sevier-Munger; Cresyl echt Violet for Nissl substance; and Gallocynin stain for Nissl granules were used to assess various patterns of cell death and degenerative changes. Complex cell death mechanisms may be involved in the neuronal and axonal degeneration. These data indicate altered and differential mRNA expressions of BCL2 (anti apoptotic gene) and GADD45 (DNA damage inducible gene) in various tissues. Increased cell death and other degenerative changes noted in the susceptible regions (spinal cord and cerebellum) than the resistant region (cerebrum), may indicate complex molecular pathways via altered BCL2 and GADD45 gene expression, causing the homeostatic imbalance between cell survival and cell death mechanisms. Semi quantitative

  16. Cholesterol-lowering effects and mechanisms in view of bile acid pathway of resveratrol and resveratrol-glucuronides

    Science.gov (United States)

    Resveratrol (Res) was previously reported to be capable of lowering plasma TC and LDL-C. The mechanism behind Res is not clearly understood, although it is presumed to have an effect on bile acid metabolism in the liver: a significant way in eliminating cholesterol from the body. As one of the major...

  17. Oxalic acid pretreatment for mechanical pulping greatly improves paper strength while maintaining scattering power and reducing shives and triglycerides

    Science.gov (United States)

    Ross Swaney; Masood Akhtar; Eric Horn; Michael Lentz; John Klungness; Marc Sabourin

    2003-01-01

    In this paper we introduce a new technology based on a mild chemical pretreatment process prior to mechanical pulping. Chips are treated with a dilute solution of oxalic acid (OA) for only 10 minute at 130°C, in a typical example. The properties of the pulp produced by this OA process are quite different from those obtained via conventional chemical pretreatments,...

  18. Systemic administration of valproic acid and zonisamide promotes the survival and differentiation of induced pluripotent stem cell–derived dopaminergic neurons

    Directory of Open Access Journals (Sweden)

    Tatsuya eYoshikawa

    2013-02-01

    Full Text Available Cell replacement therapy using embryonic stem cells (ESCs and induced pluripotent stem cells (iPSCs is a promising strategy for the treatment of neurologic diseases such as Parkinson’s disease (PD. However, a limiting factor for effective cell transplantation is the low survival rate of grafted cells, especially neurons. In this study, we modified the host environment and investigated whether the simultaneous administration of soluble factors can improve the survival and differentiation of murine iPSC-derived dopaminergic (DA neurons in host brains. With the goal of applying this technology in clinical settings in the near future, we selected drugs that were already approved for clinical use. The drugs included two commonly used anticonvulsants, valproic acid (VPA and zonisamide (ZNS, and estradiol (E2, also known as biologically active estrogen. Following neural induction of murine iPSCs, we collected neural progenitor cells by sorting PSA-NCAM+ cells, then treated the PSA-NCAM+ cells with drugs for four days. An immunofluorescence study revealed that 0.01 mM and 0.1 mM of VPA and 10 nM of E2 increased the percentage of tyrosine hydroxylase+ (TH: a DA neuron marker cells in vitro. Furthermore, 0.1 mM of VPA increased the percentage of TH+ cells that simultaneously express the midbrain markers FOXA2 and NURR1. Next, in order to determine the effects of the drugs in vivo, the iPSC-derived NPCs were transplanted into the striata of intact SD rats. The animals received intraperitoneal injections of one of the drugs for four weeks, then were subjected to an immunofluorescence study. VPA administration (150 mg/kg/daily increased the number of NeuN+ postmitotic neurons and TH+ DA neurons in the grafts. Furthermore, VPA (150 mg/kg/daily and ZNS (30 mg/kg/daily increased the number of TH+FOXA2+ midbrain DA neurons. These results suggest that the systemic administration of VPA and ZNS may improve the efficiency of cell replacement therapy using i

  19. Quantum mechanical determinations of reaction mechanisms, acid base, and redox properties of nitrogen oxides and their donors.

    Science.gov (United States)

    Dutton, Andrew S; Fukuto, Jon M; Houk, K N

    2005-01-01

    This chapter reviews computational methods based on quantum mechanics and commonly used commercial programs for the exploration of chemical phenomena, particularly in the field of nitrogen oxides. Examples from the literature are then used to demonstrate the application of these methods to the chemistry and biochemistry of various nitrogen oxides. These examples include determining reaction mechanisms using computed reaction energies, predicting rates of reactions using transition state theory, and determining chemical properties such as hydration equilibria, pKa's, and reduction potentials.

  20. Association of left ventricular mechanical dyssynchrony with survival benefit from revascularization: a study of gated positron emission tomography in patients with ischemic LV dysfunction and narrow QRS

    Energy Technology Data Exchange (ETDEWEB)

    AlJaroudi, Wael [Imaging Institute, Heart and Vascular, Cleveland, OH (United States); Sydell and Arnold Miller Family Heart and Vascular Institute, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Cleveland, OH (United States); Alraies, M.C. [Cleveland Clinic, Department of Hospital Medicine, Cleveland, OH (United States); Hachamovitch, Rory; Jaber, Wael A.; Brunken, Richard; Cerqueira, Manuel D.; Marwick, Thomas [Imaging Institute, Heart and Vascular, Cleveland, OH (United States)

    2012-10-15

    LV mechanical dyssynchrony (LVMD) is a risk marker in narrow QRS cardiomyopathy, but its association with treatment outcome is not well defined. We determined the incremental prognostic value of LVMD in ischemic cardiomyopathy, and assessed its interaction with scar, myocardium in jeopardy and subsequent revascularization. Stress and rest {sup 82}Rb gated PET were performed in 486 consecutive patients (66 {+-} 11 years of age, 82 % men, LV ejection fraction 26 {+-} 6 %) with ischemic cardiomyopathy and QRS <120 ms. LVMD was determined as the standard deviation (SD) of the regional time to minimum volume on phase analysis of the gated PET scan. A propensity score was determined to adjust for nonrandomized referral after imaging to coronary artery bypass grafting (CABG). In a Cox proportional hazards model used to determine the association between measures of LVMD and survival time, CABG was included as a time-dependent covariate and the use of an implantable cardiac defibrillator (ICD) after imaging was modeled as a stratification factor. Over 1.9 {+-} 1.4 years, 96 patients (20 %) underwent CABG and 108 (22 %) died. LVMD was a predictor of mortality (HR 1.16. 95 % CI 1.03;1.30, per 10 increase in phase SD, p = 0.02) after adjusting for baseline covariates, prior ICD use, the use of postimaging CABG, and other imaging data. There was a significant interaction between phase SD and CABG. Nested Cox models showed that LVMD carried prognostic information incremental to clinical variables, ejection fraction and CABG. LVMD is an independent predictor of all-cause mortality in ischemic cardiomyopathy, and may identify patients with a differential survival benefit from CABG versus medical therapy. (orig.)

  1. Absorbability, Mechanism and Structure-Property Relationship of Three Phenolic Acids from the Flowers of Trollius chinensis

    Directory of Open Access Journals (Sweden)

    Xiu-Wen Wu

    2014-11-01

    Full Text Available The absorption properties, mechanism of action, and structure-property relationship of three phenolic acids isolated from the flowers of Trollius chinensis Bunge, namely, proglobeflowery acid (PA, globeflowery acid (GA and trolloside (TS, were investigated using the human Caco-2 cell monolayer model. The results showed that these three phenolic acids were transported across the Caco-2 cell monolayer in a time and concentration dependent manner at the Papp level of 10−5 cm/s, and their extent of absorption correlated with their polarity and molecular weight. In conclusion, all three of these compounds were easily absorbed through passive diffusion, which implied their high bioavailability and significant contribution to the effectiveness of T. chinensis.

  2. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

    Science.gov (United States)

    Widdows, Kate L.; Panitchob, Nuttanont; Crocker, Ian P.; Please, Colin P.; Hanson, Mark A.; Sibley, Colin P.; Johnstone, Edward D.; Sengers, Bram G.; Lewis, Rohan M.; Glazier, Jocelyn D.

    2015-01-01

    Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [14C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [14C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms. PMID:25761365

  3. Effect and mechanism of dioscin from Dioscorea spongiosa on uric acid excretion in animal model of hyperuricemia.

    Science.gov (United States)

    Zhang, Yi; Jin, Lijun; Liu, Jinchang; Wang, Wei; Yu, Haiyang; Li, Jian; Chen, Qian; Wang, Tao

    2018-03-25

    Dioscin, a spirostane glycoside, the rhizoma of Dioscorea septemloba (Diocoreacea) is used for diuresis, rheumatism, and joints pain. Given the poor solubility and stability of Dioscin, we proposed a hypothesis that Dioscin's metabolite(s) are the active substance(s) in vivo to contribute to the reducing effects on serum uric acid levels. The aim of this study is to identify the active metabolite(s) of Dioscin in vivo and to explore the mechanism of its antihyperuricemic activity. After oral administration of Dioscin in potassium oxonate (PO) induced hyperuricemia rats and adenine-PO induced hyperuricemia mice models, serum uric acid and creatinine levels, clearance of uric acid and creatinine, fractional excretion of uric acid, and renal pathological lesions were determined were used to evaluate the antihyperuricemic effects. Renal glucose transporter-9 (GLUT-9) and organic anion transporter-1 (OAT-1) expressions were analyzed by western blotting method. Renal uric acid excretion was evaluated using stably urate transporter-1 (URAT-1) transfected human epithelial kidney cell line. Intestinal uric acid excretion was evaluated by measuring the transcellular transport of uric acid in HCT116 cells. In hyperuricemia rats, both 25 and 50mg/kg of oral Dioscin decreased serum uric acid levels over 4h. In the hyperuricemia mice, two weeks treatment of Dioscin significantly decreased serum uric acid and creatinine levels, increased clearance of uric acid and creatinine, increased fractional excretion of uric acid, and reduced renal pathological lesions caused by hyperuricemia. In addition, renal GLUT -9 was significantly down-regulated and OAT-1 was up-regulated in Dioscin treated hyperuricemia mice. Dioscin's metabolite Tigogenin significantly inhibited uric acid re-absorption via URAT1 from 10 to 100μM. Diosgenin and Tigogenin increased uric acid excretion via ATP binding cassette subfamily G member 2 (ABCG2). Decreasing effect of Dioscin on serum uric acid level and

  4. Combinatorial and sequential delivery of gemcitabine and oseltamivir phosphate from implantable poly(D,L-lactic-co-glycolic acid cylinders disables human pancreatic cancer cell survival

    Directory of Open Access Journals (Sweden)

    Allison Logan S

    2017-07-01

    Full Text Available Stephanie Allison Logan,1 Amanda J Brissenden,1 Myron R Szewczuk,2 Ronald J Neufeld1 1Department of Chemical Engineering, 2Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, ON, Canada Abstract: Combination therapies against multiple targets are currently being developed to prevent resistance to a single chemotherapeutic agent and to extirpate pre-existing resistance in heterogeneous cancer cells in tumors due to selective pressure from the single agent. Gemcitabine (GEM, a chemotherapeutic agent, is the current standard of care for patients with pancreatic cancer. Patients with pancreatic cancer receiving GEM have a low progression-free survival. Given the poor response rate to GEM, cancer cells are known to develop rapid resistance to this drug. Metronomic chemotherapy using combinatorial and sequential delivery systems are novel developmental approaches to disrupt tumor neovascularization, reduce systemic drug toxicity, and increase the sensitivity of chemotherapeutics in cancer. Here, implantable double-layered poly(D,L-lactic-co-glycolic acid (PLGA cylinders were engineered to sequentially release GEM in combination with oseltamivir phosphate (OP over an extended time. Double-layered PLGA cylindrical implants loaded with these active hydrophilic drugs were fabricated with minimal loss of drugs during the formulation, enabling extensive control of drug loading and establishing uniform drug distribution throughout the polymer matrix. OP is used in the formulation because of its anticancer drug properties targeting mammalian neuraminidase 1 (Neu1 involved in multistage tumorigenesis. OP and GEM encapsulated in inner/outer GEMin/OPout or OPin/GEMout implantable PLGA double-layered cylinders displayed sustained near linear release over 30 days. OP and GEM released from the double-layered cylinders effectively reduced cell viability in pancreatic cancer cell line PANC1 and its GEM-resistant variant for up to 15

  5. Mechanism of Synergistic Inhibition of Listeria monocytogenes Growth by Lactic Acid, Monolaurin, and Nisin▿

    OpenAIRE

    Tokarskyy, Oleksandr; Marshall, Douglas L.

    2008-01-01

    The combined lactic acid, monolaurin, and nisin effects on time-to-detection (optical density at 600 nm) extension were greater (P < 0.05) than any single or paired combination effect, which demonstrates a synergistic interaction among the antimicrobials. Monolaurin exposure caused C12:0 cell membrane incorporation. Lactic acid caused increased monolaurin C12:0 membrane incorporation, while nisin had no influence. We postulate that lactic acid-enhanced monolaurin C12:0 incorporation into the ...

  6. Mechanism of synergistic inhibition of Listeria monocytogenes growth by lactic acid, monolaurin, and nisin.

    Science.gov (United States)

    Tokarskyy, Oleksandr; Marshall, Douglas L

    2008-12-01

    The combined lactic acid, monolaurin, and nisin effects on time-to-detection (optical density at 600 nm) extension were greater (P Monolaurin exposure caused C12:0 cell membrane incorporation. Lactic acid caused increased monolaurin C12:0 membrane incorporation, while nisin had no influence. We postulate that lactic acid-enhanced monolaurin C12:0 incorporation into the cell membrane increased membrane fluidity resulting in increased nisin activity.

  7. Mechanism of Synergistic Inhibition of Listeria monocytogenes Growth by Lactic Acid, Monolaurin, and Nisin▿

    Science.gov (United States)

    Tokarskyy, Oleksandr; Marshall, Douglas L.

    2008-01-01

    The combined lactic acid, monolaurin, and nisin effects on time-to-detection (optical density at 600 nm) extension were greater (P Monolaurin exposure caused C12:0 cell membrane incorporation. Lactic acid caused increased monolaurin C12:0 membrane incorporation, while nisin had no influence. We postulate that lactic acid-enhanced monolaurin C12:0 incorporation into the cell membrane increased membrane fluidity resulting in increased nisin activity. PMID:18820062

  8. Azelaic Acid: Evidence-based Update on Mechanism of Action and Clinical Application.

    Science.gov (United States)

    Schulte, Brian C; Wu, Wesley; Rosen, Ted

    2015-09-01

    Azelaic acid is a complex molecule with many diverse activities. The latter include anti-infective and anti-inflammatory action. The agent also inhibits follicular keratinization and epidermal melanogenesis. Due to the wide variety of biological activities, azelaic acid has been utilized as a management tool in a broad spectrum of disease states and cutaneous disorders. This paper reviews the clinical utility of azelaic acid, noting the quality of the evidence supporting each potential use.

  9. Phytoagents for Cancer Management: Regulation of Nucleic Acid Oxidation, ROS, and Related Mechanisms

    OpenAIRE

    Lee, Wai-Leng; Huang, Jing-Ying; Shyur, Lie-Fen

    2013-01-01

    Accumulation of oxidized nucleic acids causes genomic instability leading to senescence, apoptosis, and tumorigenesis. Phytoagents are known to reduce the risk of cancer development; whether such effects are through regulating the extent of nucleic acid oxidation remains unclear. Here, we outlined the role of reactive oxygen species in nucleic acid oxidation as a driving force in cancer progression. The consequential relationship between genome instability and cancer progression highlights th...

  10. Mechanical and moisture barrier properties of titanium dioxide nanoparticles and halloysite nanotubes reinforced polylactic acid (PLA)

    Science.gov (United States)

    Alberton, J.; Martelli, S. M.; Fakhouri, F. M.; Soldi, V.

    2014-08-01

    Polylactic acid (PLA) has been larger used in biomedical field due to its low toxicity and biodegradability. The aim of this study was to produce PLLA nanocomposites, by melt extrusion, containing Halloysite nanotubes (HNT) and/or titanium dioxide (TiO2) nanoparticles. Immediately after drying, PLLA was mechanically homogenized with the nanofillers and then melt blended using a single screw extruder (L/D = 30) at a speed of 110 rpm, with three heating zones in which the following temperatures were maintained: 150, 150 and 160°C (AX Plasticos model AX14 LD30). The film samples were obtained by compression molding in a press with a temperature profile of 235 ± 5°C for 2.5 min, after pressing, films were cooled up to room temperature. The mechanical tests were performed according to ASTM D882-09 and the water vapor permeability (WVP) was measured according to ASTM E-96, in triplicate. The tensile properties indicated that the modulus was improved with increased TiO2 content up to 1g/100g PLLA. The Young's modulus (YM) of the PLA was increased from 3047 MPa to 3222 MPa with the addition of 1g TiO2/100g PLLA. The tensile strength (TS) of films increases with the TiO2 content. In both cases, the YM and TS are achieved at the 1% content of TiO2 and is due to the reinforcing effect of nanoparticles. Pristine PLA showed a strain at break (SB) of 3.56%, while the SB of nanocomposites were significant lower, for instance the SB of composite containing 7.5 g HNT/100g PLLA was around 1.90 %. The WVP of samples was increased by increasing the nano filler content. It should be expected that an increase of nanofiller content would decrease the mass transfer of water molecules throughout the samples due to the increase in the way water molecules will have to cross to permeate the material. However, this was not observed. Therefore, this result can be explained considering the molecular structure of both fillers, which contain several hydroxyl groups in the surface, making the

  11. Preparation of crosslinked poly (acryloyloxyethyltrimethyl ammonium chloride) microsphere and its adsorption and mechanism towards shikimic acid.

    Science.gov (United States)

    Men, Jiying; Wang, Ruixin; Li, Huan; Li, Xinyan; Yang, Shanshan; Liu, Haisi; Gao, Baojiao

    2017-02-01

    Shikimic acid (SA) is a key raw material for the synthesis of the antiviral drug, but its extraction and separation from plants is still limited. Crosslinked poly (acryloyloxyethyltrimethyl ammonium chloride, DAC) microspheres were synthesized via inverse-phase suspension polymerization. In the synthesizing, N,N'-methylene bisacrylamide (MBA) was used as crosslinker, cyclohexane as dispersed medium and span-60 as dispersants, obtaining CPDAC gel microspheres. The effect of polymerization condition on balling performance and the characteristics of CPDAC were examined. The adsorption properties of CPDAC towards SA were mainly explored and the data of adsorption isotherm were analyzed by using Langmuir, Freundlich, Temkin, Sips and Toth models. Furthermore, the adsorption mechanism was analyzed in depth, and the adsorption thermodynamics was also investigated. The results show that in order to prepare CPDAC, water phase must be added dropwise to oil phase, and the volume ratio of oil-water is more than 2:1. The mean diameter of CPDAC decreases with increasing span-60 and accelerating agitating rate. The strong electrostatic interaction is formed between quaternary ammonium nitrogen of CPDAC and COO - of SA. The adsorption kinetic data is fitted well with pseudo-first-order model. The adsorption ability is higher in aqueous water than ethanol, reaching 108mg/g, and Toth model is more suitable for describing the actual adsorption process. The adsorption of CPDAC towards SA is dependent on the pH value of the medium. The adsorption process is exothermic, the adsorption amount decreases with the increase of temperature, and the process is driven by enthalpy. The adsorption amount decreases with the increase of salinity. The reusability of CPDAC towards SA can keep 86.1% at the sixth cycle. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Mechanisms of Radionuclide-Hyroxycarboxylic Acid Interactions for Decontamination of Metallic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    A.J. Francis; C.J. Dodge; J.B. Gillow; G.P. Halada; C.R. Clayton

    2002-04-24

    Is this EMSP program we investigated the key fundamental issues involved in the use of simple and safe methods for the removal of radioactive contamination from equipment and facilities using hydroxycarboxylic acids. Specifically, we investigate (i) the association of uranium with various iron oxides commonly formed on corroding plain carbon steel surfaces, (ii) the association of uranium with corroding metal coupons under a variety of conditions, and (iii) the decontamination of the uranium contaminated metal coupons by citric acid or citric acid formulations containing oxalic acid and hydrogen peroxide.

  13. Folic acid and colorectal cancer prevention: molecular mechanisms and epidemiological evidence (Review).

    Science.gov (United States)

    Ströhle, Alexander; Wolters, Maike; Hahn, Andreas

    2005-06-01

    Epidemiological studies suggest that a diet rich in fruits and vegetables protects against colorectal cancer. This effect may result from their high levels of folic acid (pteroylglutamic acid). Folic acid holds a key position in DNA synthesis and mitosis as well as DNA methylation and regulation of gene expression. Folic acid deficiency has been associated with site- and gene specific DNA hypo- and hypermethylation. Furthermore thymidylate synthesis is restricted by folic acid deficiency which causes misincorporation of nucleotides and DNA strand breaks. Much epidemiological evidence supports the hypothesis that insufficient folic acid supply favors the development of colorectal tumors, particularly prospective studies have supported this connection. However, the data from case-control studies are less consistent. Functional polymorphisms in folate-metabolizing genes, especially the methylenetetrahydrofolate reductase (MTHFR) are capable of modifying the risk of colorectal cancer. Observational studies show that individuals with the homozygote genotype for the MTHFR (677C-->T) polymorphism are at higher risk when folic acid supply is low. Currently there are only few human intervention trials which show that folic acid can modify and inhibit the development of colorectal tumors. Additional studies are required in order to determine whether folic acid will be a useful agent in colorectal cancer prevention.

  14. Transcriptomics and proteomic studies reveal acaricidal mechanism of octadecanoic acid-3, 4 - tetrahydrofuran diester against Sarcoptes scabiei var. cuniculi.

    Science.gov (United States)

    Song, Xu; Chen, Zhenzhen; Jia, Renyong; Cao, Mei; Zou, Yuanfeng; Li, Lixia; Liang, Xiaoxia; Yin, Lizi; He, Changliang; Yue, Guizhou; Yin, Zhongqiong

    2017-03-31

    In our previous study, a new compound, octadecanoic acid-3, 4-tetrahydrofuran diester, possessing potent acaricidal activity was obtained from neem oil. This study performed RNA-seq transcriptomics and iTRAQ proteomics to uncover the acaricidal mechanism of the compound against Sarcoptes scabiei var. cuniculi. The results of transcriptomics indicated that after treatment with octadecanoic acid-3, 4-tetrahydrofuran diester, genes related to "Energy metabolism" were significantly up-/down-regulated, including citrate cycle, oxidative phosphorylation pathway and fatty acid metabolism. Proteomics analysis showed accordant changes of proteins related to oxidative phosphorylation pathway. The target proteins of the compound were NADH dehydrogenase, Ubiquinol-cytochrome c reductase, Cytochrome c oxidase, ATP synthase, enolase and superoxide dismutase. In transcriptomics-proteomics correlation analysis, the concordance rate between protein abundances and their corresponding mRNAs was 57%, while others (43%) were discordant changes, suggesting divergent regulating effects of octadecanoic acid-3, 4-tetrahydrofuran diester. These results suggested that the acaricidal mechanism of octadecanoic acid-3, 4-tetrahydrofuran diester attributed to interference with energy metabolism, especially oxidative phosphorylation pathway.

  15. Uric acid therapy improves the outcomes of stroke patients treated with intravenous tissue plasminogen activator and mechanical thrombectomy.

    Science.gov (United States)

    Chamorro, Ángel; Amaro, Sergio; Castellanos, Mar; Gomis, Meritxell; Urra, Xabier; Blasco, Jordi; Arenillas, Juan F; Román, Luis S; Muñoz, Roberto; Macho, Juan; Cánovas, David; Marti-Fabregas, Joan; Leira, Enrique C; Planas, Anna M

    2017-06-01

    Background Numerous neuroprotective drugs have failed to show benefit in the treatment of acute ischemic stroke, making the search for new treatments imperative. Uric acid is an endogenous antioxidant making it a drug candidate to improve stroke outcomes. Aim To report the effects of uric acid therapy in stroke patients receiving intravenous thrombolysis and mechanical thrombectomy. Methods Forty-five patients with proximal vessel occlusions enrolled in the URICO-ICTUS trial received intravenous recombinant tissue plasminogen activator within 4.5 h after stroke onset and randomized to intravenous 1000 mg uric acid or placebo (NCT00860366). These patients also received mechanical thrombectomy because a brain computed tomogaphy angiography confirmed the lack of proximal recanalization at the end of systemic thrombolysis. The primary outcome was good functional outcome at 90 days (modified Rankin Score 0-2). Safety outcomes included mortality, symptomatic intracerebral bleeding, and gout attacks. Results The rate of successful revascularization was >80% in the uric acid and the placebo groups but good functional outcome was observed in 16 out of 24 (67%) patients treated with uric acid and 10 out of 21 (48%) treated with placebo (adjusted Odds Ratio, 6.12 (95% CI 1.08-34.56)). Mortality was observed in two out of 24 (8.3%) patients treated with uric acid and one out of 21 (4.8%) treated with placebo (adjusted Odds Ratio, 3.74 (95% CI 0.06-226.29)). Symptomatic cerebral bleeding and gout attacks were similar in both groups. Conclusions Uric acid therapy was safe and improved stroke outcomes in stroke patients receiving intravenous thrombolysis followed by thrombectomy. Validation of this simple strategy in a larger trial is urgent.

  16. Influence of various acids on the physico–mechanical properties of ...

    Indian Academy of Sciences (India)

    of the calcium salts formed are dependent on the chemical character of anion. The acidic attack is affected by the processes of decomposition and leaching of the constituent of cement matrix (Gutt & Harrison 1997; Mehta 1986). An acidic media may achieve values under 7, predominantly 6 and lower. However, pH values ...

  17. The Pleiotropic Antibacterial Mechanisms of Ursolic Acid against Methicillin-Resistant Staphylococcus aureus (MRSA).

    Science.gov (United States)

    Wang, Chao-Min; Jhan, Yun-Lian; Tsai, Shang-Jie; Chou, Chang-Hung

    2016-07-07

    (1) BACKGROUND: Several triterpenoids were found to act synergistically with classes of antibiotic, indicating that plant-derived chemicals have potential to be used as therapeutics to enhance the activity of antibiotics against multidrug-resistant pathogens. However, the mode of action of triterpenoids against bacterial pathogens remains unclear. The objective of this study is to evaluate the interaction between ursolic acid against methicillin-resistant Staphylococcus aureus (MRSA); (2) METHODS: The ability of ursolic acid to damage mammalian and bacterial membranes was examined. The proteomic response of methicillin-resistant S. aureus in ursolic acid treatment was investigated using two-dimensional (2D) proteomic analysis; (3) RESULTS: Ursolic acid caused the loss of staphylococcal membrane integrity without hemolytic activity. The comparison of the protein pattern of ursolic acid-treated and normal MRSA cells revealed that ursolic acid affected a variety of proteins involved in the translation process with translational accuracy, ribonuclease and chaperon subunits, glycolysis and oxidative responses; (4) CONCLUSION: The mode of action of ursolic acid appears to be the influence on the integrity of the bacterial membrane initially, followed by inhibition of protein synthesis and the metabolic pathway. These findings reflect that the pleiotropic effects of ursolic acid against MRSA make it a promising antibacterial agent in pharmaceutical research.

  18. Biological effects of propionic acid in humans; metabolism, potential applications and underlying mechanisms

    NARCIS (Netherlands)

    Al-Lahham, Sa'ad H.; Peppelenbosch, Maikel P.; Roelofsen, Han; Vonk, Roel J.; Venema, Koen

    2010-01-01

    Undigested food is fermented in the colon by the microbiota and gives rise to various microbial metabolites. Short-chain fatty acids (SCFA), including acetic, propionic and butyric acid, are the principal metabolites produced However, most of the literature focuses on butyrate and to a lesser extent

  19. Study of the mechanism and kinetics of the reduction of uranyl ions in phosphoric acid solutions

    International Nuclear Information System (INIS)

    El Kacemi, K.; Tyburce, B.; Belcadi, S.

    1982-01-01

    The electrochemical reduction of uranyl ions in 0.1 to 9 M phosphoric acid has been investigated by polarography, cyclic voltammetry, chronopotentiometry and potentiostatic coulometry. In concentrated phosphoric acid solutions (H 3 PO 4 3 PO 4 concentrations. So, when the concentration of U(VI) increases and/or that of H 3 PO 4 reduces, the system becomes reversible. (author)

  20. Kinetics and mechanism of the oxidation of some neutral and acidic ...

    Indian Academy of Sciences (India)

    Unknown

    The effect of solvent composition indicate that the rate of reaction increases with increase in the po- larity of the medium. Addition of ... oxidation of several neutral and acidic α-amino ac- ids by TBATB in aqueous acetic acid solution, and the mechanistic aspects are discussed in this paper. 2. Experimental. 2.1 Materials.

  1. Inhibitory mechanism of l-glutamic acid on spawning of the starfish Patiria (Asterina) pectinifera.

    Science.gov (United States)

    Mita, Masatoshi

    2017-03-01

    l-Glutamic acid was previously identified as an inhibitor of spawning in the starfish Patiria (Asterina) pectinifera; this study examined how l-glutamic acid works. Oocyte release from ovaries of P. pectinifera occurred after germinal vesicle breakdown (GVBD) and follicular envelope breakdown (FEBD) when gonads were incubated ex vivo with either relaxin-like gonad-stimulating peptide (RGP) or 1-methyladenine (1-MeAde). l-Glutamic acid blocked this spawning phenotype, causing the mature oocytes to remain within the ovaries. Neither RGP-induced 1-MeAde production in ovarian follicle cells nor 1-MeAde-induced GVBD and FEBD was affected by l-glutamic acid. l-Glutamic acid may act through metabotropic receptors in the ovaries to inhibit spawning, as l-(+)-2-amino-4-phosphonobutyric acid, an agonist for metabotropic glutamate receptors, also inhibited spawning induced by 1-MeAde. Application of acetylcholine (ACH) to ovaries under inhibitory conditions with l-glutamic acid, however, brought about spawning, possibly by inducing contraction of the ovarian wall to discharge mature oocytes from the ovaries concurrently with GVBD and FEBD. Thus, l-glutamic acid may inhibit ACH secretion from gonadal nerve cells in the ovary. Mol. Reprod. Dev. 84: 246-256, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. Kinetics and mechanism of the oxidation of formic and oxalic acids ...

    Indian Academy of Sciences (India)

    Unknown

    In the complexes (A) and (B), the formal oxidation state of iodine is +1. Despite the lack of evidence for the existence of discrete I+ ions, its stable complexes with donors have been known for a long time 11,12. The formation of positive iodine species in the sulphuric acid medium has been reported recently 13. Acetic acid is ...

  3. Naringenin inhibits seed germination and seedling root growth through a salicylic acid-independent mechanism in Arabidopsis thaliana.

    Science.gov (United States)

    Hernández, Iker; Munné-Bosch, Sergi

    2012-12-01

    Flavonoids fulfill an enormous range of biological functions in plants. In seeds, these compounds play several roles; for instance proanthocyanidins protect them from moisture, pathogen attacks, mechanical stress, UV radiation, etc., and flavonols have been suggested to protect the embryo from oxidative stress. The present study aimed at determining the role of flavonoids in Arabidopsis thaliana (L.) seed germination, and the involvement of salicylic acid (SA) and auxin (indole-3-acetic acid), two phytohormones with the same biosynthetic origin as flavonoids, the shikimate pathway, in such a putative role. We show that naringenin, a flavanone, strongly inhibits the germination of A. thaliana seeds in a dose-dependent and SA-independent manner. Altered auxin levels do not affect seed germination in Arabidopsis, but impaired auxin transport does, although to a minor extent. Naringenin and N-1-naphthylphthalamic acid (NPA) impair auxin transport through the same mechanisms, so the inhibition of germination by naringenin might involve impaired auxin transport among other mechanisms. From the present study it is concluded that naringenin inhibits the germination of Arabidopsis seeds in a dose-dependent and SA-independent manner, and the results also suggest that such effects are exerted, at least to some extent, through impaired auxin transport, although additional mechanisms seem to operate as well. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  4. Alternation of host plants as a survival mechanism of leafhoppers Dilobopterus costalimai and Oncometopia facialis (Hemiptera: Cicadellidae, vectors of the Citrus Variegated Chlorosis (CVC

    Directory of Open Access Journals (Sweden)

    Milanez José Maria

    2001-01-01

    Full Text Available Dilobopterus costalimai (Young and Oncometopia facialis (Signoret are two of the most important species of citrus leafhoppers, vectors of bacterium Xylella fastidiosa which causes the Citrus Variegated Chlorosis (CVC disease. To develop a rearing technique for these species under laboratory conditions, the egg laying preference and nymph development were studied in different breeding systems: Rangpur lime (Citrus limonia and "falso boldo" (Vernonia condensata as host plants. Trials were set up in a randomized block design with three treatments (n=8. Females of D. costalimai had particular preference for ovipositing on Rangpur lime leaves while O. facialis females placed a higher number of eggs on "falso boldo", but it did not differ statistically from the Rangpur lime. The nymphal viability of D. costalimai was null in Rangpur lime and 58% in "falso boldo". For O. facialis the nymphal viability was 25 and 78% in Rangpur lime and "falso boldo", respectively. "Falso boldo" is more suitable as a host plant to rear the two species of citrus leafhoppers. The alternation of host plants seems to be an important survival mechanism of the CVC-vector species, as shown in natural conditions.

  5. A Novel Combination of Wheat Peptides and Fucoidan Attenuates Ethanol-Induced Gastric Mucosal Damage through Anti-Oxidant, Anti-Inflammatory, and Pro-Survival Mechanisms

    Directory of Open Access Journals (Sweden)

    Juntao Kan

    2017-09-01

    Full Text Available Gastritis or peptic ulcer is believed to affect about half of people worldwide. Traditional medications can lead to adverse effects, therefore, alternative nutritional strategies are needed to prevent the development of gastric mucosal damage. A novel combination of two food-grade ingredients, wheat peptides and fucoidan (WPF, was prepared to treat male Sprague Dawley rats for 30 days before gastric mucosal damage was induced by oral administration of ethanol. The serum levels of biomarkers were determined by enzyme-linked immunosorbent assay. Biomarkers in stomach tissue were analyzed using immunohistochemistry. In addition, human gastric epithelial cell line (GES-1 was used to investigate protein expression by Western blot. WPF could attenuate ethanol-induced gastric mucosal damage in an inverse dose-dependent manner, with both ulcer index and pathological index improved. WPF increased superoxide dismutase level and decreased malondialdehyde level. WPF also decreased the levels of interleukin-8, platelet-activating factor, and Caspase 3, while increasing the levels of prostaglandin E-2, epidermal growth factor (EGF, and EGF receptor (EGFR. Furthermore, phosphorylation of EGFR and extracellular signal–regulated kinases was induced by WPF in GES-1 cells. In conclusion, the novel combination of wheat peptides and fucoidan attenuated ethanol-induced gastric mucosal damage in rats through anti-oxidant, anti-inflammatory, and pro-survival mechanisms.

  6. Photo-induced oxidative damage to dissolved free amino acids by the photosensitizer polycyclic musk tonalide: Transformation kinetics and mechanisms.

    Science.gov (United States)

    Fang, Hansun; Gao, Yanpeng; Wang, Honghong; Yin, Hongliang; Li, Guiying; An, Taicheng

    2017-05-15

    Residue from the polycyclic musks (PCMs) in household and personal care products may harm human beings through skin exposure. To understand the health effects of PCMs when exposed to sunlight at molecular level, both experimental and computational methods were employed to investigate the photosensitized oxidation performance of 19 natural amino acids, the most basic unit of life. Results showed that a typical PCM, tonalide, acts as a photosensitizer to significantly increase photo-induced oxidative damage to amino acids. Both common and exceptional transformation pathways occurred during the photosensitization damage of amino acids. Experimental tests further identified the different mechanisms involved. The common transformation pathway occurred through the electron transfer from α amino-group of amino acids, accompanying with the formation of O 2 •- . This pathway was controlled by the electronic density of N atom in α amino-group. The exceptional transformation pathway was identified only for five amino acids, mainly due to the reactions with reactive oxygen species, e.g. 1 O 2 and excited triplet state molecules. Additionally, tonalide photo-induced transformation products could further accelerate the photosensitization of all amino acids with the common pathway. This study may support the protection of human health, and suggests the possible need to further restrict polycyclic musks use. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Effect of oxalic acid on the optical, thermal, dielectric and mechanical behaviour of ADP crystals

    International Nuclear Information System (INIS)

    Rajesh, P.; Ramasamy, P.

    2009-01-01

    The effect of the addition, over a concentration range from 1 to 5 mol%, of oxalic acid on the growth rate, optical transparency, hardness, dielectric behaviour, and SHG efficiency of ammonium dihydrogen phosphate single crystals grown by slow evaporation method has been investigated. UV-Vis studies show that the transparency of the oxalic acid added crystals decreased gradually. Thermal studies indicate that the decomposition temperatures of the crystal are decreased in oxalic acid added ADP crystals. It is observed from the dielectric measurements that the dielectric constant and dielectric loss increase with increase in temperature for all the crystals. Vicker's microhardness study reveals that the addition of higher concentration of oxalic acid decreases the hardness of the crystal. SHG efficiency of 1 mol% of oxalic acid is higher than the pure ADP.

  8. Omega-3 fatty acids and non-alcoholic fatty liver disease: Evidence of efficacy and mechanism of action.

    Science.gov (United States)

    Scorletti, Eleonora; Byrne, Christopher D

    2018-03-22

    For many years it has been known that high doses of long chain omega-3 fatty acids are beneficial in the treatment of hypertriglyceridaemia. Over the last three decades, there has also been a wealth of in vitro and in vivo data that has accumulated to suggest that long chain omega-3 fatty acid treatment might be beneficial to decrease liver triacylglycerol. Several biological mechanisms have been identified that support this hypothesis; notably, it has been shown that long chain omega-3 fatty acids have a beneficial effect: a) on bioactive metabolites involved in inflammatory pathways, and b) on alteration of nuclear transcription factor activities such as peroxisome proliferator-activated receptors (PPARs), sterol regulatory element-binding protein 1c (SREBP-1c) and carbohydrate-responsive element-binding protein (ChREBP), involved in inflammatory pathways and liver lipid metabolism. Since the pathogenesis of non alcoholic fatty liver disease (NAFLD) begins with the accumulation of liver lipid and progresses with inflammation and then several years later with development of fibrosis; it has been thought in patients with NAFLD omega-3 fatty acid treatment would be beneficial in treating liver lipid and possibly also in ameliorating inflammation. Meta-analyses (of predominantly dietary studies and small trials) have tended to support the assertion that omega-3 fatty acids are beneficial in decreasing liver lipid, but recent randomised controlled trials have produced conflicting data. These trials have suggested that omega-3 fatty acid might be beneficial in decreasing liver triglyceride (docosahexanoic acid also possibly being more effective than eicosapentanoic acid) but not in decreasing other features of steatohepatitis (or liver fibrosis). The purpose of this review is to discuss recent evidence regarding biological mechanisms by which long chain omega-3 fatty acids might act to ameliorate liver disease in NAFLD; to consider the recent evidence from randomised

  9. Mechanisms Regulating Acid-Base Transporter Expression in Breast- and Pancreatic Cancer

    DEFF Research Database (Denmark)

    Gorbatenko, Andrej

    Breast cancer is the most commonly diagnosed cancer in women, and the second most frequent cause of death from cancer in women. Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer with only a 5% 5-year survival rate. Both types of cancer form solid tumors...

  10. In silico approach to investigating the adsorption mechanisms of short chain perfluorinated sulfonic acids and perfluorooctane sulfonic acid on hydrated hematite surface.

    Science.gov (United States)

    Feng, Hongru; Lin, Yuan; Sun, Yuzhen; Cao, Huiming; Fu, Jianjie; Gao, Ke; Zhang, Aiqian

    2017-05-01

    Short chain perfluorinated sulfonic acids (PFSAs) that were introduced as alternatives for perfluorooctane sulfonic acid (PFOS) have been widely produced and used. However, few studies have investigated the environmental process of short chain PFSAs, and the related adsorption mechanisms still need to be uncovered. The water-oxide interface is one of the major environmental interfaces that plays an important role in affecting the adsorption behaviour and transport potential of the environmental pollutant. In this study, we performed molecular dynamics simulations and quantum chemistry calculations to investigate the adsorption mechanisms of five PFSAs and their adsorption on hydrated hematite surface as well. Different to the vertical configuration reported for PFOS on titanium oxide, all PFSAs share the same adsorption configuration as the long carbon chains parallel to the surface. The formation of hydrogen bonds between F and inter-surface H helps to stabilize the unique configuration. As a result, the sorption capacity increases with increasing C-F chain length. Moreover, both calculated adsorption energy and partial density of states (PDOS) analysis demonstrate a PFSAs adsorption mechanism in between physical and chemical adsorption because the hydrogen bonds formed by the overlap of F (p) orbital and H (s) orbital are weak intermolecular interactions while the physical adsorption are mainly ascribed to the electrostatic interactions. This massive calculation provides a new insight into the pollutant adsorption behaviour, and in particular, may help to evaluate the environmental influence of pollutants. Copyright © 2017. Published by Elsevier Ltd.

  11. The David V Valve-Sparing Root Replacement Provides Improved Survival Compared With Mechanical Valve-conduits in the Treatment of Young Patients With Aortic Root Pathology.

    Science.gov (United States)

    Esaki, Jiro; Leshnower, Bradley G; Binongo, Jose N; Lasanajak, Yi; McPherson, LaRonica; Halkos, Michael E; Guyton, Robert A; Chen, Edward P

    2016-11-01

    Valve-sparing root replacement (VSRR) is an attractive therapy for aortic root aneurysms; however, there is a paucity of data comparing VSRR with conventional root replacement using a mechanical valve-conduit (MECH). This study evaluates and compares outcomes of VSRR and MECH. A retrospective review from 2002 to 2015 at a US academic center identified 444 patients who underwent VSRR (282 patients) or MECH (162 patients). Propensity score matching was performed, based on 22 preoperative and intraoperative characteristics, and 87 matched pairs were identified. There was no difference in mean age between the groups (VSRR 45.0 years, MECH 44.2 years, p = 0.59). The incidence of Marfan syndrome (VSRR 10.3%, MECH 12.6%, p = 0.63), type A acute aortic dissection (VSRR 25.3%, MECH 27.6%, p = 0.73), reoperation (VSRR 23.0%, MECH 21.8%, p = 0.86), and arch replacement (VSRR 54.0%, MECH 52.9%, p = 0.88) were similar in both groups. Ejection fraction was similar (VSRR 52.8% ± 10.9%, MECH 52.4% ± 11.7%, p = 0.83). Operative mortality was 2.3% with VSRR and 8.0% with MECH (p = 0.10). There were no significant differences in renal failure requiring dialysis (VSRR 1.1%, MECH 4.6%, p = 0.24), permanent neurologic dysfunction (VSRR 2.3%, MECH 6.9%, p = 0.16), and pacemaker implantation (VSRR 1.1%, MECH 1.1%, p = 0.99) between the groups. Survival at 7 years was significantly improved in patients who underwent VSSR (VSRR 85.5%, MECH 73.6%, p = 0.03). In comparison with patients undergoing MECH, there is improved midterm survival among patients undergoing VSRR, with similar operative mortality and morbidity. For appropriately selected patients, VSRR provides an attractive and potentially superior alternative to MECH. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  12. Eicosapentaenoic acid inhibits intestinal β-carotene absorption by downregulation of lipid transporter expression via PPAR-α dependent mechanism.

    Science.gov (United States)

    Mashurabad, Purna Chandra; Kondaiah, Palsa; Palika, Ravindranadh; Ghosh, Sudip; Nair, Madhavan K; Raghu, Pullakhandam

    2016-01-15

    The involvement of lipid transporters, the scavenger receptor class B, type I (SR-BI) and Niemann-Pick type C1 Like 1 protein (NPC1L1) in carotenoid absorption is demonstrated in intestinal cells and animal models. Dietary ω-3 fatty acids are known to possess antilipidemic properties, which could be mediated by activation of PPAR family transcription factors. The present study was conducted to determine the effect of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), on intestinal β-carotene absorption. β-carotene uptake in Caco-2/TC7 cells was inhibited by EPA (p intestinal β-carotene absorption by down regulation of SR B1 expression via PPARα dependent mechanism and provide an evidence for dietary modulation of intestinal β-carotene absorption. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Study on the interaction mechanism between aromatic amino acids and quercetin

    Science.gov (United States)

    Gou, Xingxing; Pu, Xiaohua; Li, Zongxiao

    2017-11-01

    In this paper, we selected quercetin and aromatic amino acids (tryptophan, tyrosine, phenylalanine) as the research objects to investigate the change rules in the reaction process. The thermodynamic functions (Ka, Δ G, and Δ S) of the interactions between quercetin and aromatic amino acids (tryptophan, tyrosine, phenylalanine) were measured by isothermal titration calorimetry. The values of binding constant (Ka) reached maximum at 25°C; the entropies and Gibbs free energies were both negative at different temperatures. The kinetic parameters of quercetin and amino acids in the interaction process was determined by microcalorimetry. The results inferred that the driving force of the reaction was hydrogen bond or van der Waals force.

  14. Molecular mechanisms of cis-urocanic acid and permethrin-induced alterations in cutaneous immunity.

    Science.gov (United States)

    Prater, M R; Blaylock, B L; Holladay, S D

    2003-12-01

    Cutaneous cis-urocanic acid (cUCA) or ultraviolet B exposure has been shown to cause diminished cutaneous contact hypersensitivity (CH) and to induce systemic tolerance (increased regulatory T lymphocytes) in mice. Permethrin is also a known CH inhibitor, but the molecular mechanisms are currently poorly understood. In this study, CH was evaluated in four strains of mice: an immunosensitive strain (C57BL/6N), an immunoresistant strain (SvImJ), a strain developed from C57BL/6N mice but genetically altered at both the tumor necrosis factor-alpha receptors (TNFalphap55R and p75R), and a strain developed from C57BL/6N but genetically deleted at the interferon-gamma (IFNgamma) locus. CH was evaluated in each group via oxazolone challenge following a 5-day exposure to intradermal (ID) cUCA or a single exposure to topical permethrin, or co-exposure to both chemicals in 5-week-old female C57BL/6N, SvImJ, and C57BL/6N mice genetically altered at the TNFalpha or IFNgamma locus. A 5-day exposure to ID cUCA or a single exposure to topical permethrin resulted in diminished CH response in C57BL/6N mice, and this effect was exacerbated with concurrent exposure to both chemicals. CH in SvImJ was both cUCA- and permethrin-resistant relative to C57BL/6N mice, as 5-day cUCA or a single exposure to permethrin did not diminish CH, nor did concurrent exposure to cUCA and permethrin. Mice deleted at both TNFalphaR loci displayed similar but somewhat blunted diminished CH responses to cUCA or permethrin. This trend became significant with combined chemical exposure. IFNgamma knockout mice displayed similar diminished CH responses to cUCA or permethrin alone. Unlike C57BL/6N mice, the IFNgamma knockout mice did not show a further reduction in CH with combined chemical exposure. These results suggest the following: (1)Mouse strains show variable susceptibility to permethrin- and cUCA-induced immunomodulation. (2)TNFalpha may be involved in the immunomodulatory effects of cUCA and permethrin

  15. Data of thermal degradation and dynamic mechanical properties of starch–glycerol based films with citric acid as crosslinking agent

    Directory of Open Access Journals (Sweden)

    Paula González Seligra

    2016-06-01

    Full Text Available Interest in biodegradable edible films as packaging or coating has increased because their beneficial effects on foods. In particular, food products are highly dependents on thermal stability, integrity and transition process temperatures of the packaging. The present work describes a complete data of the thermal degradation and dynamic mechanical properties of starch–glycerol based films with citric acid (CA as crosslinking agent described in the article titled: “Biodegradable and non-retrogradable eco-films based on starch–glycerol with citric acid as crosslinking agent” González Seligra et al. (2016 [1]. Data describes thermogravimetric and dynamical mechanical experiences and provides the figures of weight loss and loss tangent of the films as a function of the temperature.

  16. Data of thermal degradation and dynamic mechanical properties of starch-glycerol based films with citric acid as crosslinking agent.

    Science.gov (United States)

    González Seligra, Paula; Medina Jaramillo, Carolina; Famá, Lucía; Goyanes, Silvia

    2016-06-01

    Interest in biodegradable edible films as packaging or coating has increased because their beneficial effects on foods. In particular, food products are highly dependents on thermal stability, integrity and transition process temperatures of the packaging. The present work describes a complete data of the thermal degradation and dynamic mechanical properties of starch-glycerol based films with citric acid (CA) as crosslinking agent described in the article titled: "Biodegradable and non-retrogradable eco-films based on starch-glycerol with citric acid as crosslinking agent" González Seligra et al. (2016) [1]. Data describes thermogravimetric and dynamical mechanical experiences and provides the figures of weight loss and loss tangent of the films as a function of the temperature.

  17. Stearic acid coating on circulating fluidized bed combustion fly ashes and its effect on the mechanical performance of polymer composites

    International Nuclear Information System (INIS)

    Yao, Nina; Zhang, Ping; Song, Lixian; Kang, Ming; Lu, Zhongyuan; Zheng, Rong

    2013-01-01

    The aim of this work was to test circulating fluidized bed combustion fly ashes (CFAs) for its potential to be utilized in polymer composites manufacturing to improve its toughness. CFAs was coated by stearic acid and used in the composite of polypropylene/ethylene vinyl acetate/high density polyethylene (PP/EVA/HDPE) by molding process method. The resulting coated and uncoated CFAs were fully characterized by particle size analyzer, contact angles, powder X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stearic acid coated onto the surface of CFAs particles in the physical and chemical ways, and the total clad ratio reached 2.05% by measuring TGA/DTA curve. The percentage of CFAs particles focused to a narrow range 2–4 μm and the median mean size was 3.2 μm more than uncoated CFAs. The properties of hydrophobic and dispersive of CFAs particles improved and original activity was reserved after stearic acid coating. The stearic acid was verified as a coupling agent by how much effect it had on the mechanical properties. It showed the elongation at break of PP/EVA/HDPE reinforced with 15 wt% coated CFAs (c-CFAs) was 80.20% and higher than that of the uncoated. The stearic acid treatment of CFAs is a very promising approach to improve the mechanical strength due to the incorporation of stearic acid on the CFAs surface, and hence, further enhances the potential for recycling CFAs as a suitable filler material in polymer composites.

  18. Stearic acid coating on circulating fluidized bed combustion fly ashes and its effect on the mechanical performance of polymer composites

    Science.gov (United States)

    Yao, Nina; Zhang, Ping; Song, Lixian; Kang, Ming; Lu, Zhongyuan; Zheng, Rong

    2013-08-01

    The aim of this work was to test circulating fluidized bed combustion fly ashes (CFAs) for its potential to be utilized in polymer composites manufacturing to improve its toughness. CFAs was coated by stearic acid and used in the composite of polypropylene/ethylene vinyl acetate/high density polyethylene (PP/EVA/HDPE) by molding process method. The resulting coated and uncoated CFAs were fully characterized by particle size analyzer, contact angles, powder X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stearic acid coated onto the surface of CFAs particles in the physical and chemical ways, and the total clad ratio reached 2.05% by measuring TGA/DTA curve. The percentage of CFAs particles focused to a narrow range 2-4 μm and the median mean size was 3.2 μm more than uncoated CFAs. The properties of hydrophobic and dispersive of CFAs particles improved and original activity was reserved after stearic acid coating. The stearic acid was verified as a coupling agent by how much effect it had on the mechanical properties. It showed the elongation at break of PP/EVA/HDPE reinforced with 15 wt% coated CFAs (c-CFAs) was 80.20% and higher than that of the uncoated. The stearic acid treatment of CFAs is a very promising approach to improve the mechanical strength due to the incorporation of stearic acid on the CFAs surface, and hence, further enhances the potential for recycling CFAs as a suitable filler material in polymer composites.

  19. Cellular mechanisms underlying the inhibitory effect of flufenamic acid on chloride secretion in human intestinal epithelial cells

    Directory of Open Access Journals (Sweden)

    Pawin Pongkorpsakol

    2017-06-01

    Full Text Available Intestinal Cl− secretion is involved in the pathogenesis of secretory diarrheas including cholera. We recently demonstrated that flufenamic acid (FFA suppressed Vibrio cholerae El Tor variant-induced intestinal fluid secretion via mechanisms involving AMPK activation and NF-κB-suppression. The present study aimed to investigate the effect of FFA on transepithelial Cl− secretion in human intestinal epithelial (T84 cells. FFA inhibited cAMP-dependent Cl− secretion in T84 cell monolayers with IC50 of ∼8 μM. Other fenamate drugs including tolfenamic acid, meclofenamic acid and mefenamic acid exhibited the same effect albeit with lower potency. FFA also inhibited activities of CFTR, a cAMP-activated apical Cl− channel, and KCNQ1/KCNE3, a cAMP-activated basolateral K+ channel. Mechanisms of CFTR inhibition by FFA did not involve activation of its negative regulators. Interestingly, FFA inhibited Ca2+-dependent Cl− secretion with IC50 of ∼10 μM. FFA inhibited activities of Ca2+-activated Cl− channels and KCa3.1, a Ca2+-activated basolateral K+ channels, but had no effect on activities of Na+–K+–Cl− cotransporters and Na+–K+ ATPases. These results indicate that FFA inhibits both cAMP and Ca2+-dependent Cl− secretion by suppressing activities of both apical Cl− channels and basolateral K+ channels. FFA and other fenamate drugs may be useful in the treatment of secretory diarrheas.

  20. Effect of acid treated carbon nanotubes on mechanical, rheological and thermal properties of polystyrene nanocomposites

    KAUST Repository

    Amr, Issam Thaher

    2011-09-01

    In this work, multiwall carbon nanotubes (CNT) were functionalized by acid treatment and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). Polystyrene/CNT composites of both the untreated and acid treated carbon nanotubes were prepared by thermal bulk polymerization without any initiator at different loadings of CNT. The tensile tests showed that the addition of 0.5 wt.% of acid treated CNT results in 22% increase in Young\\'s modulus. The DSC measurements showed a decrease in glass transition temperature (Tg) of PS in the composites. The rheological studies at 190 °C showed that the addition of untreated CNT increases the viscoelastic behavior of the PS matrix, while the acid treated CNT acts as plasticizer. Thermogravimetric analysis indicated that the incorporation of CNT into PS enhanced the thermal properties of the matrix polymer. © 2011 Elsevier Ltd. All rights reserved.