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Sample records for surface sialic acid

  1. Expanding the diversity of unnatural cell surface sialic acids

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    Luchansky, Sarah J.; Goon, Scarlett; Bertozzi, Carolyn R.

    2003-10-30

    Novel chemical reactivity can be introduced onto cell surfaces through metabolic oligosaccharide engineering. This technique exploits the substrate promiscuity of cellular biosynthetic enzymes to deliver unnatural monosaccharides bearing bioorthogonal functional groups into cellular glycans. For example, derivatives of N-acetylmannosamine (ManNAc) are converted by the cellular biosynthetic machinery into the corresponding sialic acids and subsequently delivered to the cell surface in the form of sialoglycoconjugates. Analogs of N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) are also metabolized and incorporated into cell surface glycans, likely through the sialic acid and GalNAc salvage pathways, respectively. Furthermore, GlcNAc analogs can be incorporated into nucleocytoplasmic proteins in place of {beta}-O-GlcNAc residues. These pathways have been exploited to integrate unique electrophiles such as ketones and azides into the target glycoconjugate class. These functional groups can be further elaborated in a chemoselective fashion by condensation with hydrazides and by Staudinger ligation, respectively, thereby introducing detectable probes onto the cell. In conclusion, sialic acid derivatives are efficient vehicles for delivery of bulky functional groups to cell surfaces and masking of their hydroxyl groups improves their cellular uptake and utilization. Furthermore, the successful introduction of photoactivatable aryl azides into cell surface glycans opens up new avenues for studying sialic acid-binding proteins and elucidating the role of sialic acid in essential processes such as signaling and cell adhesion.

  2. Macrophage-mediated tumor cytotoxicity: role of macrophage surface sialic acid.

    Science.gov (United States)

    Cameron, D J

    1983-02-01

    Cell surface sialic acid levels were compared for monocytes and macrophages obtained from normal volunteers and breast cancer patients. Equal quantities of sialic acid were found on the monocytes obtained from normal volunteers and breast cancer patients. Approximately 60% more cell surface sialic acid was found on the macrophages from breast cancer patients than was found on the macrophages from normal volunteers. In order to determine whether cell surface sialic acid had any effect on macrophage-mediated cytotoxicity, macrophages were pretreated with neuraminidase (NANAse) prior to co-cultivation with tumor cells. The normal macrophages, after neuraminidase treatment, no longer retained their ability to kill tumor cells. However, when macrophages from breast cancer patients were treated with NANAse, no difference was observed in the ability of untreated and NANAse treated macrophages to kill tumor cells.

  3. Sialic acid-to-urea ratio as a measure of airway surface hydration.

    Science.gov (United States)

    Esther, Charles R; Hill, David B; Button, Brian; Shi, Shuai; Jania, Corey; Duncan, Elizabeth A; Doerschuk, Claire M; Chen, Gang; Ranganathan, Sarath; Stick, Stephen M; Boucher, Richard C

    2017-03-01

    Although airway mucus dehydration is key to pathophysiology of cystic fibrosis (CF) and other airways diseases, measuring mucus hydration is challenging. We explored a robust method to estimate mucus hydration using sialic acid as a marker for mucin content. Terminal sialic acid residues from mucins were cleaved by acid hydrolysis from airway samples, and concentrations of sialic acid, urea, and other biomarkers were analyzed by mass spectrometry. In mucins purified from human airway epithelial (HAE), sialic acid concentrations after acid hydrolysis correlated with mucin concentrations (r(2) = 0.92). Sialic acid-to-urea ratios measured from filters applied to the apical surface of cultured HAE correlated to percent solids and were elevated in samples from CF HAEs relative to controls (2.2 ± 1.1 vs. 0.93 ± 1.8, P gold standard measure of mucus hydration. The method proved robust and has potential to serve as flexible techniques to assess mucin hydration, particularly in samples like BALF in which established methods such as percent solids cannot be utilized.

  4. General consideration on sialic acid chemistry.

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    Cao, Hongzhi; Chen, Xi

    2012-01-01

    Sialic acids, also known as neuraminic acids, are a family of negatively charged α-keto acids with a nine-carbon backbone. These unique sugars have been found at the termini of many glycan chains of vertebrate cell surface, which play pivotal roles in mediating or modulating a variety of physiological and pathological processes. This brief review covers general approaches for synthesizing sialic acid containing structures. Recently developed synthetic methods along with structural diversities and biological functions of sialic acid are discussed.

  5. Plasma sialic acid alterations in neoplastic diseases.

    Science.gov (United States)

    Dwivedi, C; Dixit, M; Kumar, S S; Reddy, H; Semenya, K A; Hardy, R E

    1987-01-01

    The several types of neoplastic transformations are accompanied by alterations in the composition of cell glycoproteins, which are major structural components of cell surfaces. One such observed alteration is in the level of sialic acid on the cell surface. In the present investigation, plasma sialic acid levels were measured in normal volunteers and neoplastic patients using thiobarbituric acid spectrophotometric methods. The mean plasma sialic acid level from 124 normal volunteers was 3.0 mumol/ml. The mean for 20 non-malignant patients was 3.2 mumol/ml. Such observed mean values of sialic acid were 3.7 mumol/ml in 64 breast cancer patients, 5.1 mumol/ml in 22 lung cancer patients, 4.1 mumol/ml in 20 colon patients, and 5.0 mumol/ml in 26 patients having ovarian, cervix, pancreas, prostate, thyroid, uterine, squamous cell, esophageal and endometrial cancers. Serial determinations of plasma sialic acid in 15 patients correlated well with the progression and regression of disease. These results indicate that plasma sialic acid levels are elevated over control levels in the different types of cancer patients studied. Assay of plasma sialic acid is not sensitive enough to be used for screening, but could be used as a prognostic determinant in a variety of neoplastic conditions.

  6. Tethering of Ficolin-1 to cell surfaces through recognition of sialic acid by the fibrinogen-like domain

    DEFF Research Database (Denmark)

    Honore, C.; Rorvig, S.; Hummelshoj, T.;

    2010-01-01

    surface is restricted to monocytes and granulocytes. Ficolin-1 is tethered to the cell surface of these cells through its fibrinogen-like domain, and the ligand involved in the binding of Ficolin-1 is shown to be sialic acid. Moreover, rFicolin-1 bound activated but not resting T lymphocytes. Together......, these results demonstrate a novel self-recognition mechanism of leukocytes mediated by the fibrinogen-like domain of Ficolin-1....

  7. Canine and feline parvoviruses preferentially recognize the non-human cell surface sialic acid N-glycolylneuraminic acid

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    Löfling, Jonas [Departments of Medicine and Cellular and Molecular Medicine, Glycobiology Research and Training Center, Center for Academic Research and Training in Anthropogeny, 9500 Gilman Drive, University of California, San Diego, La Jolla, CA 92093 (United States); Michael Lyi, Sangbom; Parrish, Colin R. [Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853 (United States); Varki, Ajit, E-mail: a1varki@ucsd.edu [Departments of Medicine and Cellular and Molecular Medicine, Glycobiology Research and Training Center, Center for Academic Research and Training in Anthropogeny, 9500 Gilman Drive, University of California, San Diego, La Jolla, CA 92093 (United States)

    2013-05-25

    Feline panleukopenia virus (FPV) is a pathogen whose canine-adapted form (canine parvovirus (CPV)) emerged in 1978. These viruses infect by binding host transferrin receptor type-1 (TfR), but also hemagglutinate erythrocytes. We show that hemagglutination involves selective recognition of the non-human sialic acid N-glycolylneuraminic acid (Neu5Gc) but not N-acetylneuraminic acid (Neu5Ac), which differs by only one oxygen atom from Neu5Gc. Overexpression of α2-6 sialyltransferase did not change binding, indicating that both α2-3 and α2-6 linkages are recognized. However, Neu5Gc expression on target cells did not enhance CPV or FPV infection in vitro. Thus, the conserved Neu5Gc-binding preference of these viruses likely plays a role in the natural history of the virus in vivo. Further studies must clarify relationships between virus infection and host Neu5Gc expression. As a first step, we show that transcripts of CMAH (which generates Neu5Gc from Neu5Ac) are at very low levels in Western dog breed cells. - Highlights: ► Feline and canine parvoviruses recognize Neu5Gc but not Neu5Ac, which differ by one oxygen atom. ► The underlying linkage of these sialic acids does not affect recognition. ► Induced Neu5Gc expression on target cells that normally express Neu5Ac did not enhance infection. ► Thus, the conserved binding preference plays an important yet unknown role in in vivo infections. ► Population and breed variations in Neu5Gc expression occur, likely by regulating the gene CMAH.

  8. Visualization of sialic acid produced on bacterial cell surfaces by lectin staining.

    Science.gov (United States)

    Kajiwara, Hitomi; Toda, Munetoyo; Mine, Toshiki; Nakada, Hiroshi; Wariishi, Hiroyuki; Yamamoto, Takeshi

    2010-01-01

    Oligosaccharides containing N-acetylneuraminic acid on the cell surface of some pathogenic bacteria are important for host-microbe interactions. N-acetylneuraminic acid (Neu5Ac) plays a major role in the pathogenicity of bacterial pathogens. For example, cell surface sialyloligosaccharide moieties of the human pathogen Haemophilus influenzae are involved in virulence and adhesion to host cells. In this study, we have established a method of visualizing Neu5Ac linked to a glycoconjugate on the bacterial cell surface based on lectin staining. Photobacterium damselae strain JT0160, known to produce a-2,6-sialyltransferase, was revealed to possess Neu5Ac by HPLC. Using the strain, a strong Sambucus sieboldiana lectin-binding signal was detected. The bacteria producing α-2,6-sialyltransferases could be divided into two groups: those with a lot of α-2,6-linked Neu5Ac on the cell surface and those with a little. In the present study, we developed a useful method for evaluating the relationship between Neu5Ac expression on the cell surface and the degree of virulence of marine bacteria.

  9. Canine and feline parvoviruses preferentially recognize the non-human cell surface sialic acid N-glycolylneuraminic acid.

    Science.gov (United States)

    Löfling, Jonas; Lyi, Sangbom Michael; Parrish, Colin R; Varki, Ajit

    2013-05-25

    Feline panleukopenia virus (FPV) is a pathogen whose canine-adapted form (canine parvovirus (CPV)) emerged in 1978. These viruses infect by binding host transferrin receptor type-1 (TfR), but also hemagglutinate erythrocytes. We show that hemagglutination involves selective recognition of the non-human sialic acid N-glycolylneuraminic acid (Neu5Gc) but not N-acetylneuraminic acid (Neu5Ac), which differs by only one oxygen atom from Neu5Gc. Overexpression of α2-6 sialyltransferase did not change binding, indicating that both α2-3 and α2-6 linkages are recognized. However, Neu5Gc expression on target cells did not enhance CPV or FPV infection in vitro. Thus, the conserved Neu5Gc-binding preference of these viruses likely plays a role in the natural history of the virus in vivo. Further studies must clarify relationships between virus infection and host Neu5Gc expression. As a first step, we show that transcripts of CMAH (which generates Neu5Gc from Neu5Ac) are at very low levels in Western dog breed cells.

  10. Determination of Sialic Acids by Acidic Ninhydrin Reaction

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    Yao,Kenzabroh

    1987-12-01

    Full Text Available A new acidic ninhydrin method for determining free sialic acids is described. The method is based on the reaction of sialic acids with Gaitonde's acid ninhydrin reagent 2 which yields a stable color with an absorption maximum at 470 nm. The standard curve is linear in the range of 5 to 500 nmol of N-acetylneuraminic acid per 0.9 ml of reaction mixture. The reaction was specific only for sialic acids among the various sugars and sugar derivatives examined. Some interference of this method by cysteine, cystine and tryptophan was noted, although their absorption maxima differed from that of sialic acids. The interference by these amino acids was eliminated with the use of a small column of cation-exchange resin. The acidic ninhydrin method provides a simple and rapid method for the determination of free sialic acids in biological materials.

  11. Preferential Lectin Binding of Cancer Cells upon Sialic Acid Treatment under Nutrient Deprivation

    OpenAIRE

    Badr, Haitham A.; ElSayed, Abdelaleim I.; Ahmed, Hafiz; Dwek, Miriam V.; Li, Chen-Zhong; Djansugurova, Leyla B.

    2013-01-01

    The terminal monosaccharide of glycoconjugates on a eukaryotic cell surface is typically a sialic acid (Neu5Ac). Increased sialylation usually indicates progression and poor prognosis of most carcinomas. Here, we utilize two human mammary epithelial cell lines, HB4A (breast normal cells) and T47D (breast cancer cells) as a model system to demonstrate differential surface glycans when treated with sialic acid under nutrient deprivation. Under a starved condition, sialic acid treatment of both ...

  12. Serum sialic acid and CEA concentrations in human breast cancer.

    OpenAIRE

    Hogan-Ryan, A.; Fennelly, J J; Jones, M.; Cantwell, B; Duffy, M J

    1980-01-01

    The concentration of bound sialic acid in the sera of 56 normal subjects and 65 subjects with breast cancer was measured, in order to determine (1) whether serum sialic acid concentrations are raised in breast cancer and (2) whether the concentration of sialic acid in serum reflects tumour stage. The amount of sialic acid in serum was compared to serum carcinoembryonic antigen (CEA) values. Urinary hydroxyproline and serum alkaline phosphatase concentrations were used as indicators of bone an...

  13. Increased expression of sialic acid in cervical biopsies with squamous intraepithelial lesions

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    Vallejo-Ruiz Verónica

    2010-11-01

    Full Text Available Abstract Background Altered sialylation has been observed during oncogenic transformation. Sialylated oligosaccharides of glycoproteins and glycolipids have been implicated in tumor progression and metastases. In the cervical cancer high levels of sialic acid have been reported in the patients serum, and an increased of total sialic acid concentration has been reported for the cervical neoplasia and cervical cancer. This study investigates the changes in expression and distribution of α2,3-linked sialic acid and α2,6- linked sialic acid in low and high squamous intraepithelial lesions and in normal tissue. Methods Lectin histochemistry was used to examine the expression and distribution of sialic acid in different grades of cervical neoplasia. We applied Maackia amurensis lectin, which interacts with α2,3-linked sialic acid and Sambucus nigra lectin specific for α2,6-linked sialic acid. Results The histochemical analysis showed that α2,3-linked sialic acid and α2,6- linked sialic acid increased in intensity and distribution in concordance with the grade of squamous intraepithelial lesion (SIL. These results are in concordance with a previous study that reports increased RNAm levels of three sialyltransferases. Conclusions These results show that the change in sialylation occurs before cancer development and may play an important role in cellular transformation. These findings provide the basis for more detailed studies of the possible role of cell surface glycoconjugates bearing sialic acid in the cellular cervix transformation.

  14. Removal of sialic acid from the surface of human MCF-7 mammary cancer cells abolishes E-cadherin-dependent cell-cell adhesion in an aggregation assay.

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    Deman, J J; Van Larebeke, N A; Bruyneel, E A; Bracke, M E; Vermeulen, S J; Vennekens, K M; Mareel, M M

    1995-09-01

    MCF-7 human breast cancer cells express E-cadherin and show, at least in some circumstances, E-cadherin-dependent cell-cell adhesion (Bracke et al., 1993). The MCF-7/AZ variant spontaneously displays E-cadherin-dependent fast aggregation; in the MCF-7/6 variant, E-cadherin appeared not to be spontaneously functional in the conditions of the fast aggregation assay, but function could be induced by incubation of the suspended cells in the presence of insulinlike growth factor I (IGF-I) (Bracke et al., 1993). E-cadherin from MCF-7 cells was shown to contain sialic acid. Treatment with neuraminidase was shown to remove this sialic acid, as well as most of the sialic acid present at the cell surface. Applied to MCF-7/AZ, and MCF-7/6 cells, pretreatment with neuraminidase abolished spontaneous as well as IGF-I induced, E-cadherin-dependent fast cell-cell adhesion of cells in suspension, as measured in the fast aggregation assay. Treatment with neuraminidase did not, however, inhibit the possibly different, but equally E-cadherin-mediated, process of cell-cell adhesion of MCF-7 cells on a flat plastic substrate as assessed by determining the percentage of cells remaining isolated (without contact with other cells) 24 h after plating.

  15. Serum sialic acid and CEA concentrations in human breast cancer.

    Science.gov (United States)

    Hogan-Ryan, A; Fennelly, J J; Jones, M; Cantwell, B; Duffy, M J

    1980-04-01

    The concentration of bound sialic acid in the sera of 56 normal subjects and 65 subjects with breast cancer was measured, in order to determine (1) whether serum sialic acid concentrations are raised in breast cancer and (2) whether the concentration of sialic acid in serum reflects tumour stage. The amount of sialic acid in serum was compared to serum carcinoembryonic antigen (CEA) values. Urinary hydroxyproline and serum alkaline phosphatase concentrations were used as indicators of bone and liver involvement. Erythrocyte sedimentation rate (ESR) was also measured. Significantly elevated serum sialic acid concentrations were found in breast cancer, and showed correlation with tumour stage. Serum sialic acid values did not correlate with CEA values. The results suggest that measurement of serum sialic acid concentrations may be of adjunctive value in assessing tumour stage.

  16. Identification of a novel sialic acid transporter in Haemophilus ducreyi.

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    Post, Deborah M B; Mungur, Rachna; Gibson, Bradford W; Munson, Robert S

    2005-10-01

    Haemophilus ducreyi, the causative agent of chancroid, produces a lipooligosaccharide (LOS) which terminates in N-acetyllactosamine. This glycoform can be further extended by the addition of a single sialic acid residue to the terminal galactose moiety. H. ducreyi does not synthesize sialic acid, which must be acquired from the host during infection or from the culture medium when the bacteria are grown in vitro. However, H. ducreyi does not have genes that are highly homologous to the genes encoding known bacterial sialic acid transporters. In this study, we identified the sialic acid transporter by screening strains in a library of random transposon mutants for those mutants that were unable to add sialic acid to N-acetyllactosamine-containing LOS. Mutants that reacted with the monoclonal antibody 3F11, which recognizes the terminal lactosamine structure, and lacked reactivity with the lectin Maackia amurensis agglutinin, which recognizes alpha2,3-linked sialic acid, were further characterized to demonstrate that they produced a N-acetyllactosamine-containing LOS by silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometric analyses. The genes interrupted in these mutants were mapped to a four-gene cluster with similarity to genes encoding bacterial ABC transporters. Uptake assays using radiolabeled sialic acid confirmed that the mutants were unable to transport sialic acid. This study is the first report of bacteria using an ABC transporter for sialic acid uptake.

  17. Sweet escape: Sialic acids in tumor immune evasion

    NARCIS (Netherlands)

    Bull, C.; Brok, M.H.M.G.M. den; Adema, G.J.

    2014-01-01

    Sialic acids represent a family of sugar molecules derived from neuraminic acid that frequently terminate glycan chains and contribute to many biological processes. Already five decades ago, aberrantly high expression of sialic acids has been proposed to protect cancer cells from recognition and era

  18. Characterisation of CMP-sialic acid transporter substrate recognition

    NARCIS (Netherlands)

    Maggioni, A.; Itzstein, M. von; Guzman, I.B. Rodriguez; Ashikov, A.M.; Stephens, A.S.; Haselhorst, T.; Tiralongo, J.

    2013-01-01

    CMP-sialic acid transporter: We report an in-depth, multidisciplinary, structural study that has identified the amino acid residues intimately involved in CMP-sialic acid transporter (CST) substrate specificity. Our data provide a significant contribution towards a better understanding the structure

  19. Insights into the evolution of sialic acid catabolism among bacteria

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    Almagro-Moreno Salvador

    2009-05-01

    Full Text Available Abstract Background Sialic acids comprise a family of nine-carbon amino sugars that are prevalent in mucus rich environments. Sialic acids from the human host are used by a number of pathogens as an energy source. Here we explore the evolution of the genes involved in the catabolism of sialic acid. Results The cluster of genes encoding the enzymes N-acetylneuraminate lyase (NanA, epimerase (NanE, and kinase (NanK, necessary for the catabolism of sialic acid (the Nan cluster, are confined 46 bacterial species, 42 of which colonize mammals, 33 as pathogens and 9 as gut commensals. We found a putative sialic acid transporter associated with the Nan cluster in most species. We reconstructed the phylogenetic history of the NanA, NanE, and NanK proteins from the 46 species and compared them to the species tree based on 16S rRNA. Within the NanA phylogeny, Gram-negative and Gram-positive bacteria do not form distinct clades. NanA from Yersinia and Vibrio species was most closely related to the NanA clade from eukaryotes. To examine this further, we reconstructed the phylogeny of all NanA homologues in the databases. In this analysis of 83 NanA sequences, Bacteroidetes, a human commensal group formed a distinct clade with Verrucomicrobia, and branched with the Eukaryotes and the Yersinia/Vibrio clades. We speculate that pathogens such as V. cholerae may have acquired NanA from a commensal aiding their colonization of the human gut. Both the NanE and NanK phylogenies more closely represented the species tree but numerous incidences of incongruence are noted. We confirmed the predicted function of the sialic acid catabolism cluster in members the major intestinal pathogens Salmonella enterica, Vibrio cholerae, V. vulnificus, Yersinia enterocolitica and Y. pestis. Conclusion The Nan cluster among bacteria is confined to human pathogens and commensals conferring them the ability to utilize a ubiquitous carbon source in mucus rich surfaces of the human body

  20. Lectin staining and Western blot data showing differential sialylation of nutrient-deprived cancer cells to sialic acid supplementation

    OpenAIRE

    Badr, Haitham A.; Dina M. M. AlSadek; Mohit P. Mathew; Chen-Zhong Li; Djansugurova, Leyla B.; Yarema, Kevin J.; Hafiz Ahmed

    2015-01-01

    This report provides data that are specifically related to the differential sialylation of nutrient deprived breast cancer cells to sialic acid supplementation in support of the research article entitled, “Nutrient-deprived cancer cells preferentially use sialic acid to maintain cell surface glycosylation" [1]. Particularly, breast cancer cells, when supplemented with sialic acid under nutrient deprivation, display sialylated glycans at the cell surface, but non-malignant mammary cells show s...

  1. Complement receptor 1 is a sialic acid-independent erythrocyte receptor of Plasmodium falciparum.

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    Carmenza Spadafora

    Full Text Available Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of erythrocyte invasion are incompletely understood. P. falciparum depends heavily on sialic acid present on glycophorins to invade erythrocytes. However, a significant proportion of laboratory and field isolates are also able to invade erythrocytes in a sialic acid-independent manner. The identity of the erythrocyte sialic acid-independent receptor has been a mystery for decades. We report here that the complement receptor 1 (CR1 is a sialic acid-independent receptor for the invasion of erythrocytes by P. falciparum. We show that soluble CR1 (sCR1 as well as polyclonal and monoclonal antibodies against CR1 inhibit sialic acid-independent invasion in a variety of laboratory strains and wild isolates, and that merozoites interact directly with CR1 on the erythrocyte surface and with sCR1-coated microspheres. Also, the invasion of neuraminidase-treated erythrocytes correlates with the level of CR1 expression. Finally, both sialic acid-independent and dependent strains invade CR1 transgenic mouse erythrocytes preferentially over wild-type erythrocytes but invasion by the latter is more sensitive to neuraminidase. These results suggest that both sialic acid-dependent and independent strains interact with CR1 in the normal red cell during the invasion process. However, only sialic acid-independent strains can do so without the presence of glycophorin sialic acid. Our results close a longstanding and important gap in the understanding of the mechanism of erythrocyte invasion by P. falciparum that will eventually make possible the development of an effective blood stage vaccine.

  2. Sialic acid, periodontal pathogens and Tannerella forsythia: stick around and enjoy the feast!

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    Stafford, G; Roy, S; Honma, K; Sharma, A

    2012-02-01

    Periodontal pathogens, like any other human commensal or pathogenic bacterium, must possess both the ability to acquire the necessary growth factors and the means to adhere to surfaces or reside and survive in their environmental niche. Recent evidence has suggested that sialic acid containing host molecules may provide both of these requirements in vivo for several periodontal pathogens but most notably for the red complex organism Tannerella forsythia. Several other periodontal pathogens also possess sialic acid scavenging enzymes - sialidases, which can also expose adhesive epitopes, but might also act as adhesins in their own right. In addition, recent experimental work coupled with the release of several genome sequences has revealed that periodontal bacteria have a range of sialic acid uptake and utilization systems while others may also use sialic acid as a cloaking device on their surface to mimic host and avoid immune recognition. This review will focus on these systems in a range of periodontal bacteria with a focus on Ta. forsythia.

  3. Independence of sialic acid levels in normal and malignant growth.

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    Khadapkar, S V; Sheth, N A; Bhide, S V

    1975-06-01

    Sialic acid content in breast or tumor tissue and serum of mouse strains that are either susceptible or resistant to breast cancer was measured at various age periods. Sialic acid content was also studied in normal lung tissue and in lung adenoma and hepatoma. Sialic acid levels during nonmalignant growth of a tissue were measured in breast tissue during pregnancy and lactation, and in regenerating liver, as well as in newborn and postnatal liver. The sialic acid content, when expressed per mg of protein, increased in mammary tumor, lung adenoma, and hepatoma. It also increased in nonmalignant growth of breast tissue during pregnancy and lactation and of regenerating liver and postnatal liver. Increase in sialic acid per mg DNA was observed only in lung tumors, regenerating liver, and postnatal liver. It appears that the changes in sialic acid level are independent of the normal or malignant growth of a tissue and that these changes might be the function of the parameter used to express the sialic acid values, i.e., either the DNA content or protein content of a given tissue.

  4. Substrate specificity of the sialic acid biosynthetic pathway

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    Jacobs, Christina L.; Goon, Scarlett; Yarema, Kevin J.; Hinderlich, Stephan; Hang, Howard C.; Chai, Diana H.; Bertozzi, Carolyn R.

    2001-07-18

    Unnatural analogs of sialic acid can be delivered to mammalian cell surfaces through the metabolic transformation of unnatural N-acetylmannosamine (ManNAc) derivatives. In previous studies, mannosamine analogs bearing simple N-acyl groups up to five carbon atoms in length were recognized as substrates by the biosynthetic machinery and transformed into cell-surface sialoglycoconjugates [Keppler, O. T., et al. (2001) Glycobiology 11, 11R-18R]. Such structural alterations to cell surface glycans can be used to probe carbohydrate-dependent phenomena. This report describes our investigation into the extent of tolerance of the pathway toward additional structural alterations of the N-acyl substituent of ManNAc. A panel of analogs with ketone-containing N-acyl groups that varied in the lengthor steric bulk was chemically synthesized and tested for metabolic conversion to cell-surface glycans. We found that extension of the N-acyl chain to six, seven, or eight carbon atoms dramatically reduced utilization by the biosynthetic machinery. Likewise, branching from the linear chain reduced metabolic conversion. Quantitation of metabolic intermediates suggested that cellular metabolism is limited by the phosphorylation of the N-acylmannosamines by ManNAc 6-kinase in the first step of the pathway. This was confirmed by enzymatic assay of the partially purified enzyme with unnatural substrates. Identification of ManNAc 6-kinase as a bottleneck for unnatural sialic acid biosynthesis provides a target for expanding the metabolic promiscuity of mammalian cells.

  5. Automated solid-phase synthesis of oligosaccharides containing sialic acids

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    Chian-Hui Lai

    2015-05-01

    Full Text Available A sialic acid glycosyl phosphate building block was designed and synthesized. This building block was used to prepare α-sialylated oligosaccharides by automated solid-phase synthesis selectively.

  6. Lectin staining and Western blot data showing differential sialylation of nutrient-deprived cancer cells to sialic acid supplementation.

    Science.gov (United States)

    Badr, Haitham A; AlSadek, Dina M M; Mathew, Mohit P; Li, Chen-Zhong; Djansugurova, Leyla B; Yarema, Kevin J; Ahmed, Hafiz

    2015-12-01

    This report provides data that are specifically related to the differential sialylation of nutrient deprived breast cancer cells to sialic acid supplementation in support of the research article entitled, "Nutrient-deprived cancer cells preferentially use sialic acid to maintain cell surface glycosylation" [1]. Particularly, breast cancer cells, when supplemented with sialic acid under nutrient deprivation, display sialylated glycans at the cell surface, but non-malignant mammary cells show sialylated glycans intracellularly. The impact of sialic acid supplementation under nutrient deprivation was demonstrated by measuring levels of expression and sialylation of two markers, EGFR1 and MUC1. This Data in Brief article complements the main manuscript by providing detailed instructions and representative results for cell-level imaging and Western blot analyses of changes in sialylation during nutrient deprivation and sialic acid supplementation. These methods can be readily generalized for the study of many types of glycosylation and various glycoprotein markers through the appropriate selection of fluorescently-labeled lectins.

  7. Preferential lectin binding of cancer cells upon sialic acid treatment under nutrient deprivation.

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    Badr, Haitham A; Elsayed, Abdelaleim I; Ahmed, Hafiz; Dwek, Miriam V; Li, Chen-Zhong; Djansugurova, Leyla B

    2013-10-01

    The terminal monosaccharide of glycoconjugates on a eukaryotic cell surface is typically a sialic acid (Neu5Ac). Increased sialylation usually indicates progression and poor prognosis of most carcinomas. Here, we utilize two human mammary epithelial cell lines, HB4A (breast normal cells) and T47D (breast cancer cells), as a model system to demonstrate differential surface glycans when treated with sialic acid under nutrient deprivation. Under a starved condition, sialic acid treatment of both cells resulted in increased activities of α2→3/6 sialyltransferases as demonstrated by solid phase assay using lectin binding. However, a very strong Maackia amurensis agglutinin I (MAL-I) staining on the membrane of sialic acid-treated T47D cells was observed, indicating an increase of Neu5Acα2→3Gal on the cell surface. To our knowledge, this is a first report showing the utility of lectins, particularly MAL-I, as a means to discriminate between normal and cancer cells after sialic acid treatment under nutrient deprivation. This method is sensitive and allows selective detection of glycan sialylation on a cancer cell surface.

  8. Detection of Sialic Acid-Utilising Bacteria in a Caecal Community Batch Culture Using RNA-Based Stable Isotope Probing

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    Wayne Young

    2015-03-01

    Full Text Available Sialic acids are monosaccharides typically found on cell surfaces and attached to soluble proteins, or as essential components of ganglioside structures that play a critical role in brain development and neural transmission. Human milk also contains sialic acid conjugated to oligosaccharides, glycolipids, and glycoproteins. These nutrients can reach the large bowel where they may be metabolised by the microbiota. However, little is known about the members of the microbiota involved in this function. To identify intestinal bacteria that utilise sialic acid within a complex intestinal community, we cultured the caecal microbiota from piglets in the presence of 13C-labelled sialic acid. Using RNA-based stable isotope probing, we identified bacteria that consumed 13C-sialic acid by fractionating total RNA in isopycnic buoyant density gradients followed by 16S rRNA gene analysis. Addition of sialic acid caused significant microbial community changes. A relative rise in Prevotella and Lactobacillus species was accompanied by a corresponding reduction in the genera Escherichia/Shigella, Ruminococcus and Eubacterium. Inspection of isotopically labelled RNA sequences suggests that the labelled sialic acid was consumed by a wide range of bacteria. However, species affiliated with the genus Prevotella were clearly identified as the most prolific users, as solely their RNA showed significantly higher relative shares among the most labelled RNA species. Given the relevance of sialic acid in nutrition, this study contributes to a better understanding of their microbial transformation in the intestinal tract with potential implications for human health.

  9. Sialic Acid Binding Properties of Soluble Coronavirus Spike (S1 Proteins: Differences between Infectious Bronchitis Virus and Transmissible Gastroenteritis Virus

    Directory of Open Access Journals (Sweden)

    Christine Winter

    2013-07-01

    Full Text Available The spike proteins of a number of coronaviruses are able to bind to sialic acids present on the cell surface. The importance of this sialic acid binding ability during infection is, however, quite different. We compared the spike protein of transmissible gastroenteritis virus (TGEV and the spike protein of infectious bronchitis virus (IBV. Whereas sialic acid is the only receptor determinant known so far for IBV, TGEV requires interaction with its receptor aminopeptidase N to initiate infection of cells. Binding tests with soluble spike proteins carrying an IgG Fc-tag revealed pronounced differences between these two viral proteins. Binding of the IBV spike protein to host cells was in all experiments sialic acid dependent, whereas the soluble TGEV spike showed binding to APN but had no detectable sialic acid binding activity. Our results underline the different ways in which binding to sialoglycoconjugates is mediated by coronavirus spike proteins.

  10. The sialic acid binding activity of the S protein facilitates infection by porcine transmissible gastroenteritis coronavirus

    Directory of Open Access Journals (Sweden)

    Enjuanes Luis

    2011-09-01

    Full Text Available Abstract Background Transmissible gastroenteritis virus (TGEV has a sialic acid binding activity that is believed to be important for enteropathogenicity, but that has so far appeared to be dispensable for infection of cultured cells. The aims of this study were to determine the effect of sialic acid binding for the infection of cultured cells under unfavorable conditions, and comparison of TGEV strains and mutants, as well as the avian coronavirus IBV concerning their dependence on the sialic acid binding activity. Methods The infectivity of different viruses was analyzed by a plaque assay after adsorption times of 5, 20, and 60 min. Prior to infection, cultured cells were either treated with neuraminidase to deplete sialic acids from the cell surface, or mock-treated. In a second approach, pre-treatment of the virus with porcine intestinal mucin was performed, followed by the plaque assay after a 5 min adsorption time. A student's t-test was used to verify the significance of the results. Results Desialylation of cells only had a minor effect on the infection by TGEV strain Purdue 46 when an adsorption period of 60 min was allowed for initiation of infection. However, when the adsorption time was reduced to 5 min the infectivity on desialylated cells decreased by more than 60%. A TGEV PUR46 mutant (HAD3 deficient in sialic acid binding showed a 77% lower titer than the parental virus after a 5 min adsorption time. After an adsorption time of 60 min the titer of HAD3 was 58% lower than that of TGEV PUR46. Another TGEV strain, TGEV Miller, and IBV Beaudette showed a reduction in infectivity after neuraminidase treatment of the cultured cells irrespective of the virion adsorption time. Conclusions Our results suggest that the sialic acid binding activity facilitates the infection by TGEV under unfavorable environmental conditions. The dependence on the sialic acid binding activity for an efficient infection differs in the analyzed TGEV strains.

  11. Sialic Acid Glycobiology Unveils Trypanosoma cruzi Trypomastigote Membrane Physiology.

    Directory of Open Access Journals (Sweden)

    Andrés B Lantos

    2016-04-01

    Full Text Available Trypanosoma cruzi, the flagellate protozoan agent of Chagas disease or American trypanosomiasis, is unable to synthesize sialic acids de novo. Mucins and trans-sialidase (TS are substrate and enzyme, respectively, of the glycobiological system that scavenges sialic acid from the host in a crucial interplay for T. cruzi life cycle. The acquisition of the sialyl residue allows the parasite to avoid lysis by serum factors and to interact with the host cell. A major drawback to studying the sialylation kinetics and turnover of the trypomastigote glycoconjugates is the difficulty to identify and follow the recently acquired sialyl residues. To tackle this issue, we followed an unnatural sugar approach as bioorthogonal chemical reporters, where the use of azidosialyl residues allowed identifying the acquired sugar. Advanced microscopy techniques, together with biochemical methods, were used to study the trypomastigote membrane from its glycobiological perspective. Main sialyl acceptors were identified as mucins by biochemical procedures and protein markers. Together with determining their shedding and turnover rates, we also report that several membrane proteins, including TS and its substrates, both glycosylphosphatidylinositol-anchored proteins, are separately distributed on parasite surface and contained in different and highly stable membrane microdomains. Notably, labeling for α(1,3Galactosyl residues only partially colocalize with sialylated mucins, indicating that two species of glycosylated mucins do exist, which are segregated at the parasite surface. Moreover, sialylated mucins were included in lipid-raft-domains, whereas TS molecules are not. The location of the surface-anchored TS resulted too far off as to be capable to sialylate mucins, a role played by the shed TS instead. Phosphatidylinositol-phospholipase-C activity is actually not present in trypomastigotes. Therefore, shedding of TS occurs via microvesicles instead of as a fully

  12. Serum sialic acid--an important cancer marker.

    OpenAIRE

    Tewarson S; Mittal V; Singh M; Gupta G

    1993-01-01

    Total serum sialic acid (TSA), Lipid associated sialic acid (LASA), Total protein (TP) and TSA/TP factor (as cancer markers) have been estimated in 78 patients of cancer stomach, breast, colorectal region and gall bladder, before and after treatment and of varying degrees of metastasis and compared to 30 healthy controls. A significant rise in TSA and TSA/TP factor and a decrease in serum total protein levels was found in all cases of cancer. This increase was directly proportional to the deg...

  13. Tethering of Ficolin-1 to cell surfaces through recognition of sialic acid by the fibrinogen-like domain

    DEFF Research Database (Denmark)

    Honore, C.; Rorvig, S.; Hummelshoj, T.

    2010-01-01

    but is regarded primarily as a secretory molecule that exerts its function locally in inflamed tissues. Ficolin-1 has been reported on the surface of monocytes and granulocytes and was suggested originally to function as a phagocytic receptor. However, the molecule does not contain any obvious transmembrane...

  14. Titanium dioxide enrichment of sialic acid-containing glycopeptides

    DEFF Research Database (Denmark)

    Palmisano, Giuseppe; Lendal, Sara E; Larsen, Martin Røssel

    2011-01-01

    the glycosylation site of N-linked sialylated glycoproteins. The method relies on the specificity of titanium dioxide affinity chromatography to isolate sialic acid-containing glycopeptides. After enzymatic release of the glycans, the enriched sialylated glycopeptides are analyzed by mass spectrometry...

  15. Interactions of chrysotile and crocidolite asbestos with red blood cell membranes. Chrysotile binds to sialic acid.

    Science.gov (United States)

    Brody, A R; George, G; Hill, L H

    1983-10-01

    Chrysotile and crocidolite are commonly used forms of asbestos. Hemolysis has been widely used as a test of membrane injury, and it has been shown previously that chrysotile causes rapid breakdown of red blood cells (RBCs), whereas crocidolite is only weakly hemolytic. A reasonable hypothesis set forth to explain the cytotoxic effects of chrysotile maintains that positively charged chrysotile fibers bind to negatively charged sialic acid residues on RBC membranes causing clustering of membrane proteins and increased cell permeability to Na and K ions. Our studies presented here provide two lines of evidence in direct support of this hypothesis. (a) Morphologic--Ultrastructural techniques showed that both chrysotile and crocidolite asbestos bind to and distort more than 85% of RBCs treated for 15 minutes. The distorting effects of chrysotile, but not crocidolite, were almost totally ablated by pretreating the cells with neuraminidase. In addition, gold-conjugated wheat germ agglutinin was used to label the distribution of sialic acid groups on RBC membranes. Pretreatment of the RBCs with chrysotile, but not crocidolite, reduced the number of gold-conjugated wheat germ agglutinin-labeled sites to less than 30% of the control level. (b) Biochemical--The thiobarbituric acid assay was used to determine the percentage of sialic acid that remained with the cell pellet after neuraminidase and/or asbestos treatment. Asbestos treatment alone caused no release of sialic acid from the cells. Neuraminidase treatment for 3.5 hours removed more than 80% of the sialic acid from cell surfaces. Chrysotile, but not crocidolite, asbestos prevented neuraminidase-mediated removal of sialic acid from RBCs. In addition, x-ray energy spectrometry of freeze-dried cells showed that RBCs distorted by chrysotile, but not by crocidolite, exhibited significant alterations in intracellular Na:K ratios. The morphologic and biochemical data strongly support the hypothesis that chrysotile asbestos

  16. Highly sensitive SERS detection and quantification of sialic acid on single cell using photonic-crystal fiber with gold nanoparticles.

    Science.gov (United States)

    Gong, Tianxun; Cui, Ying; Goh, Douglas; Voon, Kong Kien; Shum, Perry Ping; Humbert, Georges; Auguste, Jean-Louis; Dinh, Xuan-Quyen; Yong, Ken-Tye; Olivo, Malini

    2015-02-15

    An ultrasensitive surface enhanced Raman spectroscopy (SERS) based sensing platform was developed to detect the mean sialic acid level on the surface of single cell with sensitivity as low as 2 fmol. This platform adopted the use of an interference-free Raman tag, 4-(dihydroxyborophenyl) acetylene (DBA), which selectively binds to sialic acid on the cell membrane. By loading the side channel of a photonic crystal fiber with a mixture of gold nanoparticles and DBA-tagged HeLa cell, and subsequently propagating laser light through the central solid core, strong SERS signal was obtained. This SERS technique achieved accurate detection and quantification of concentration of sialic acid on a single cell, surpassing previously reported methods that required more than 10(5) cells. Moreover, this platform can be developed into a clinical diagnostic tool to potentially analyze sialic acid-related diseases such as tumor malignancy and metastasis in real-time.

  17. Membrane sialic acid influences basophil histamine release by interfering with calcium dependence

    DEFF Research Database (Denmark)

    Jensen, C; Norn, S; Skov, P S

    1987-01-01

    The influence of the cell membrane content of sialic acid on basophil histamine release was examined in vitro in allergic patients and normal controls. Enzymatical removal of sialic acid enhanced histamine release induced by allergen and anti-IgE, whereas an increase in membrane sialic acid content....... This difference, together with the previous finding that alterations in membrane sialic acid content is reflected in the cell sensitivity to extracellular calcium, suggest an interaction between membrane sialic acid and the calcium channels involved in basophil histamine release....

  18. Multiple changes in sialic acid biology during human evolution.

    Science.gov (United States)

    Varki, Ajit

    2009-04-01

    Humans are genetically very similar to "great apes", (chimpanzees, bonobos, gorillas and orangutans), our closest evolutionary relatives. We have discovered multiple genetic and biochemical differences between humans and these other hominids, in relation to sialic acids and in Siglecs (Sia-recognizing Ig superfamily lectins). An inactivating mutation in the CMAH gene eliminated human expression of N-glycolylneuraminic acid (Neu5Gc) a major sialic acid in "great apes". Additional human-specific changes have been found, affecting at least 10 of the dietary sources, particularly red meat and milk products. As humans also have varying and sometime high levels of circulating anti-Neu5Gc antibodies, there are implications for biotechnology products, and for some human diseases associated with chronic inflammation.

  19. Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons

    Directory of Open Access Journals (Sweden)

    Chen-xu Li

    2015-01-01

    Full Text Available Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control cells. We then treated cells with divalent cations of Ca 2+ and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to specifically remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electrophoretic velocity of injured neuronal cells. These findings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

  20. Unified theory of bacterial sialometabolism: how and why bacteria metabolize host sialic acids.

    Science.gov (United States)

    Vimr, Eric R

    2013-01-01

    Sialic acids are structurally diverse nine-carbon ketosugars found mostly in humans and other animals as the terminal units on carbohydrate chains linked to proteins or lipids. The sialic acids function in cell-cell and cell-molecule interactions necessary for organismic development and homeostasis. They not only pose a barrier to microorganisms inhabiting or invading an animal mucosal surface, but also present a source of potential carbon, nitrogen, and cell wall metabolites necessary for bacterial colonization, persistence, growth, and, occasionally, disease. The explosion of microbial genomic sequencing projects reveals remarkable diversity in bacterial sialic acid metabolic potential. How bacteria exploit host sialic acids includes a surprisingly complex array of metabolic and regulatory capabilities that is just now entering a mature research stage. This paper attempts to describe the variety of bacterial sialometabolic systems by focusing on recent advances at the molecular and host-microbe-interaction levels. The hope is that this focus will provide a framework for further research that holds promise for better understanding of the metabolic interplay between bacterial growth and the host environment. An ability to modify or block this interplay has already yielded important new insights into potentially new therapeutic approaches for modifying or blocking bacterial colonization or infection.

  1. Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons

    Institute of Scientific and Technical Information of China (English)

    Chen-xu Li; Guo-ying Ma; Min-fang Guo; Ying Liu

    2015-01-01

    Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control) cells. We then treated cells with di-valent cations of Ca2+and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to speciifcally remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electro-phoretic velocity of injured neuronal cells. These ifndings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

  2. Role of sialic acid and alkaline DNase in breast cancer.

    Science.gov (United States)

    Raval, G N; Parekh, L J; Patel, M M; Patel, P S; Rawal, R M; Balar, D B; Patel, D D

    1997-01-01

    Serum levels of sialic acid and alkaline DNase (ADA) were analysed in 495 blood samples collected from 170 breast cancer patients before and during/after anticancer treatment. Fifty-six healthy females were included in the study to define the cutoff values. The markers were analysed by highly sensitive spectrophotometric methods. Statistical evaluation of the data was done using Student's 't' test, paired 't' test and ROC curve analysis. The total sialic acid (TSA), lipid bound sialic acid (LSA) and ADA in sera of untreated breast cancer patients were significantly higher than in controls. ROC curve analysis revealed TSA and LSA to be useful markers for diagnosis of breast cancer. Serum levels of TSA and LSA were significantly decreased in complete responders as compared to their pretreatment values. The pretreatment ADA values showed much individual variation. However, responders showed higher levels of ADA than untreated patients. In nonresponders the values of the biomarkers were comparable with pretreatment levels. The study suggested that TSA and LSA can be helpful in the diagnosis of breast cancer. All three markers can be used for assessment of response to anticancer treatment in breast cancer patients.

  3. QUANTITATIVE DETERMINATION OF SIALIC ACID IN INDIAN MILK AND MILK PRODUCTS

    OpenAIRE

    D.Karunanithi; V.M.Biju; A.Radhakrishna

    2013-01-01

    Background: Sialic acids are acidic sugars with a 9-carbon backbone, expressed as terminal residue on mammalian glycoconjugates. Sialic acid was found in two forms as N-acetylneuraminic acid (Neu5Ac) and N-Glycolylneuraminic acid (Neu5Gc) in meat and milk products. Neu5Ac is important for the brain and neuro development while Neu5Gc is suspected as human carcinogen. There is no data reported on sialic acid content in Indian milk and milk based products. Objective: To determine sialic acid (Ne...

  4. Are humans prone to autoimmunity? Implications from evolutionary changes in hominin sialic acid biology.

    Science.gov (United States)

    Varki, Ajit

    2017-09-01

    Given varied intrinsic and extrinsic challenges to the immune system, it is unsurprising that each evolutionary lineage evolves distinctive features of immunoreactivity, and that tolerance mechanisms fail, allowing autoimmunity. Humans appear prone to many autoimmune diseases, with mechanisms both genetic and environmental. Another rapidly evolving biological system involves sialic acids, a family of monosaccharides that are terminal caps on cell surface and secreted molecules of vertebrates, and play multifarious roles in immunity. We have explored multiple genomic changes in sialic acid biology that occurred in human ancestors (hominins), some with implications for enhanced immunoreactivity, and hence for autoimmunity. Human ancestors lost the enzyme synthesizing the common mammalian sialic acid Neu5Gc, with an accumulation of the precursor sialic acid Neu5Ac. Resulting changes include an enhanced reactivity by some immune cells and increased ability of macrophages to kill bacteria, at the cost of increased endotoxin sensitivity. There are also multiple human-specific evolutionary changes in inhibitory and activating Siglecs, immune cell receptors that recognize sialic acids as "self-associated molecular patterns" (SAMPs) to modulate immunity, but can also be hijacked by pathogen molecular mimicry of SAMPs. Altered expression patterns and fixed or polymorphic SIGLEC pseudogenization in humans has modulated both innate and adaptive immunity, sometimes favoring over-reactivity. Meanwhile, dietary intake of Neu5Gc (derived primarily from red meats) allows metabolic incorporation of this non-human molecule into human cells--apparently the first example of "xeno-autoimmunity" involving "xeno-autoantigen" interactions with circulating "xeno-autoantibodies". Taken together, some of these factors may contribute to the apparent human propensity for autoimmunity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Structural Aberrations of Cellular Sialic Acids and TheirFunctions in Cancer Metastases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Sialic acids (neuraminic acids) are a special series of 9-carbon ring negatively charged carbohydrates, which has been found to be selectively changed in malignant cells from structures (both synthesis and structure modifications) to functions (up and down regulation in cells). Sialic acids, in single forms or conjugates, have been systematically studied both in lab and in clinics by GC, GCMS, NMR, HPTLC, HPLC and other modern analytical means. Sialic acids and related conjugates are predicted to be used in cancer diagnosis, cancer prognostic forecasting, designing of cancer chemotherapy regimens, uncovering carcinogenetic processes and neoplasm metastasis. Tumor cell regulative systems and pathways are correlated with sialic acids, which can be applied to prognostic evaluation of cancer patients, and antimetastatic chemotherapy by sialic acid derivatives and analogues. Searching for new biological characteristics of sialic acids in cells have also been extensively studied these days. In this paper, main stream discoveries and advancements are provided , also discussions of possible mechanisms and hypotheses are invoked.

  6. 4-mercaptophenylboronic acid functionalized gold nanoparticles for colorimetric sialic acid detection.

    Science.gov (United States)

    Sankoh, Supannee; Thammakhet, Chongdee; Numnuam, Apon; Limbut, Warakorn; Kanatharana, Proespichaya; Thavarungkul, Panote

    2016-11-15

    A simple and selective colorimetric sensor for sialic acid detection, based on the aggregation of 4-mercaptophenylboronic acid functionalized gold nanoparticles (4-MPBA-AuNPs) was developed. The color of the solution changed from wine-red to blue after binding with sialic acid. The colorimetric sensor provided good analytical performances with a linear dynamic range of 80µM to 2.00mM and a 68±2µM limit of detection without any effect from possible interferences and sample matrix. In addition, the quantitative results were obtained within only 10min. This developed sensor was used to detect sialic acid in blood serum samples and the results were in good agreement with those from the current periodate-resorcinol method (P>0.05) thus indicating that this developed colorimetric sensor can be used as an alternative method for sialic acid detection with a shorter analysis time and a high accuracy.

  7. Comparative analysis of the sialic acid binding activity of four different IBV strains

    OpenAIRE

    2009-01-01

    Abstract Avian infectious bronchitis virus (IBV) is a major pathogen in commercial poultry flocks. Recently we demonstrated, that sialic acid serves as a receptor determinant for IBV on the tracheal epithelium. Here we compared the IBV strains Beaudette, 4/91, Italy02, and QX for their sialic acid binding properties. We demonstrate that sialic acid binding is important for the infection of primary chicken kidney cells and the tracheal epithelium by all four strains. There were only...

  8. Serum fluoride and sialic acid levels in osteosarcoma.

    Science.gov (United States)

    Sandhu, R; Lal, H; Kundu, Z S; Kharb, S

    2011-12-01

    Osteosarcoma is a rare malignant bone tumor most commonly occurring in children and young adults presenting with painful swelling. Various etiological factors for osteosarcoma are ionizing radiation, family history of bone disorders and cancer, chemicals (fluoride, beryllium, and vinyl chloride), and viruses. Status of fluoride levels in serum of osteosarcoma is still not clear. Recent reports have indicated that there is a link between fluoride exposure and osteosarcoma. Glycoproteins and glycosaminoglycans are an integral part of bone and prolonged exposure to fluoride for long duration has been shown to cause degradation of collagen and ground substance in bones. The present study was planned to analyze serum fluoride, sialic acid, calcium, phosphorus, and alkaline phosphatase levels in 25 patients of osteosarcoma and age- and sex-matched subjects with bone-forming tumours other than osteosarcoma and musculo-skeletal pain (controls, 25 each). Fluoride levels were analyzed by ISE and sialic acid was analyzed by Warren's method. Mean serum fluoride concentration was found to be significantly higher in patients with osteosarcoma as compared to the other two groups. The mean value of flouride in patients with other bone-forming tumors was approximately 50% of the group of osteosarcoma; however, it was significantly higher when compared with patients of group I. Serum sialic acid concentration was found to be significantly raised in patients with osteosarcoma as well as in the group with other bone-forming tumors as compared to the group of controls. There was, however, no significant difference in the group of patients of osteosarcoma when compared with group of patients with other bone-forming tumors. These results showing higher level of fluoride with osteosarcoma compared to others suggesting a role of fluoride in the disease.

  9. Effect of fluoride on salivary immunoglobulins and sialic acid

    Directory of Open Access Journals (Sweden)

    Kadriye Görkem Ulu Güzel

    Full Text Available Summary Objective: The aim of our study was to evaluate the effect of fluoride on salivary immunoglobulin and sialic acid levels in children with dental fluorosis and healthy teeth who live in places with high fluoride concentration in drinking water. Method: Fifty-one (51 healthy children between 6 and 12 years old with no caries were randomly selected from primary schools enrolled in the dental-care program operated by the Department of Pediatric Dentistry. The children were divided into two groups: group I comprised 26 children with dental fluorosis [Thylstrup-Fejerskov Dental Fluorosis Index (TFI = 4] who lived in Isparta (2.7-2.8 ppm, and group II consisted of 25 children without dental fluorosis who were born in low-fluoride areas and had lived in Isparta for only the previous two years. Stimulated and unstimulated saliva were collected and analyzed for fluoride, salivary immunoglobulins and sialic acid levels. Results: Sialic acid level was correlated negatively with age. Levels of secretory immunoglobulin A (sIgA and secretory immunoglobulin G (sIgG were higher in children with dental fluorosis compared with those in group II, although these differences were not significant. Conclusion: Increased sIgA and sIgG levels may arrest the progression of caries in subjects with dental fluorosis. Given the risks of dental fluorosis, further studies of the effects of different fluoride levels in drinking water on salivary composition of children with mixed dentition are needed to confirm the results of our study and to provide data for comparison.

  10. Lectin staining and Western blot data showing differential sialylation of nutrient-deprived cancer cells to sialic acid supplementation

    Directory of Open Access Journals (Sweden)

    Haitham A. Badr

    2015-12-01

    Full Text Available This report provides data that are specifically related to the differential sialylation of nutrient deprived breast cancer cells to sialic acid supplementation in support of the research article entitled, “Nutrient-deprived cancer cells preferentially use sialic acid to maintain cell surface glycosylation" [1]. Particularly, breast cancer cells, when supplemented with sialic acid under nutrient deprivation, display sialylated glycans at the cell surface, but non-malignant mammary cells show sialylated glycans intracellularly. The impact of sialic acid supplementation under nutrient deprivation was demonstrated by measuring levels of expression and sialylation of two markers, EGFR1 and MUC1. This Data in Brief article complements the main manuscript by providing detailed instructions and representative results for cell-level imaging and Western blot analyses of changes in sialylation during nutrient deprivation and sialic acid supplementation. These methods can be readily generalized for the study of many types of glycosylation and various glycoprotein markers through the appropriate selection of fluorescently-labeled lectins.

  11. A novel sialic acid utilization and uptake system in the periodontal pathogen Tannerella forsythia.

    Science.gov (United States)

    Roy, Sumita; Douglas, C W Ian; Stafford, Graham P

    2010-05-01

    Tannerella forsythia is a key contributor to periodontitis, but little is known of its virulence mechanisms. In this study we have investigated the role of sialic acid in biofilm growth of this periodontal pathogen. Our data show that biofilm growth of T. forsythia is stimulated by sialic acid, glycolyl sialic acid, and sialyllactose, all three of which are common sugar moieties on a range of important host glycoproteins. We have also established that growth on sialyllactose is dependent on the sialidase of T. forsythia since the sialidase inhibitor oseltamivir suppresses growth on sialyllactose. The genome of T. forsythia contains a sialic acid utilization locus, which also encodes a putative inner membrane sialic acid permease (NanT), and we have shown this is functional when it is expressed in Escherichia coli. This genomic locus also contains a putatively novel TonB-dependent outer membrane sialic acid transport system (TF0033-TF0034). In complementation studies using an Escherichia coli strain devoid of its outer membrane sialic acid transporters, the cloning and expression of the TF0033-TF0034 genes enabled an E. coli nanR nanC ompR strain to utilize sialic acid as the sole carbon and energy source. We have thus identified a novel sialic acid uptake system that couples an inner membrane permease with a TonB-dependent outer membrane transporter, and we propose to rename these novel sialic acid uptake genes nanO and nanU, respectively. Taken together, these data indicate that sialic acid is a key growth factor for this little-characterized oral pathogen and may be key to its physiology in vivo.

  12. Clinical usefulness of alterations in sialic acid, sialyl transferase and sialoproteins in breast cancer.

    Science.gov (United States)

    Raval, G N; Parekh, L J; Patel, D D; Jha, F P; Sainger, R N; Patel, P S

    2004-07-01

    Sialic acid, the end moieties of the carbohydrate chains are biologically important and essential for functions of glycoconjugates and are reported to be altered in cancer patients. Two hundred and twenty five breast cancer (BC) patients, 100 patients with benign breast disease (BBD) and 100 healthy females (controls) were enrolled for the study. Eight hundred and twenty four follow-up samples of 225 breast carcinoma patients were also evaluated. The association of sialic acid forms, sialyltransferase and α-2-6 sialoproteins levels with presence and extent as well as prognosis of breast carcinoma was studied. Serum sialic acid forms and sialyltransferase revealed significantly elevated levels among untreated breast cancer patients as compared to the controls, patients with BBD as well as cancer patients in remission. Non-responders showed comparable levels of the markers with those found in breast cancer patients at the time of diagnosis. Higher levels of sialic acid forms at diagnosis were associated with poor prognosis. A positive correlation between serum levels of different forms of sialic acids and extent of malignant disease was observed. The changes in serum proteins with terminal α-2-6 sialic acid correlated well with alterations in the levels of sialic acid forms and sialyltransferase. Malignant tissues showed elevated levels of sialic acid and sialyltransferase as compared to surrounding normal tissues.The results suggested potential utility of these markers in evaluation of clinical outcome.

  13. Predictive Value of Serum Sialic Acid in Type-2 Diabetes Mellitus and Its Complication (Nephropathy)

    OpenAIRE

    K, Prajna; Kumar J., Ashok; Rai, Srinidhi; Shetty, Shobith Kumar; Rai, Tirthal; Shrinidhi,; Begum, Mohamedi; MD, Shashikala

    2013-01-01

    Introduction: Sialic acid levels are increased in type-2 diabetes mellitus and its estimation helps in predicting the occurrence of microvascular complication such as diabetic nephropathy. The present study compared the levels of sialic acid, glycated haemoglobin, serum creatinine and urine microalbumin: in type-2 diabetics without any complications; in type-2 diabetics with nephropathy; and in age and sex matched healthy individual (controls).

  14. Dienophile-Modified Mannosamine Derivatives for Metabolic Labeling of Sialic Acids: A Comparative Study.

    Science.gov (United States)

    Dold, Jeremias E G A; Pfotzer, Jessica; Späte, Anne-Katrin; Wittmann, Valentin

    2017-03-20

    Sialic acids play an important role in numerous cell adhesion processes and sialylation levels are known to be altered under certain pathogenic conditions such as cancer. Metabolic glycoengineering with mannosamine derivatives is a convenient way to introduce non-natural chemical reporter groups into sialylated glycoconjugates offering the opportunity to label sialic acids using bioorthogonal ligation chemistry. The labeling intensity not only depends on the rate of the ligation reaction but also on the extent to which the natural sialic acids are replaced by the modified ones, i.e. the incorporation efficiency. Here we present a comparative study of eight mannosamine derivatives featuring terminal alkenes as chemical reporter groups that can be labeled by an inverse-electron-demand Diels-Alder (DAinv) reaction. The derivatives differ in chain length as well as the type of linkage (comprising carbamates, amides, and a urea) that connects the terminal alkene to the sugar. As a general trend, increasing chain lengths result in higher DAinv reactivity and at the same time reduced incorporation efficiency. Carbamates are better accepted than amides with the same chain length; nevertheless do the latter result in more intense cell-surface staining visible in life-cell fluorescence microscopy. Finally, a urea derivative was shown to be accepted.

  15. Liquid chromatography-tandem mass spectrometry assay for the quantification of free and total sialic acid in human cerebrospinal fluid.

    NARCIS (Netherlands)

    Ham, M. van der; Koning, T.J. de; Lefeber, D.J.; Fleer, A.; Prinsen, B.H.; Sain-van der Velden, M.G. de

    2010-01-01

    BACKGROUND: Analysis of sialic acid (SA) metabolites in cerebrospinal fluid (CSF) is important for clinical diagnosis. In the present study, a high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) method for free sialic acid (FSA) and total sialic acid (TSA) in human CSF was v

  16. Characterization of a sialate-O-acetylesterase (NanS) from the oral pathogen Tannerella forsythia that enhances sialic acid release by NanH, its cognate sialidase.

    Science.gov (United States)

    Phansopa, Chatchawal; Kozak, Radoslaw P; Liew, Li Phing; Frey, Andrew M; Farmilo, Thomas; Parker, Jennifer L; Kelly, David J; Emery, Robert J; Thomson, Rebecca I; Royle, Louise; Gardner, Richard A; Spencer, Daniel I R; Stafford, Graham P

    2015-12-01

    Tannerella forsythia, a Gram-negative member of the Bacteroidetes has evolved to harvest and utilize sialic acid. The most common sialic acid in humans is a mono-N-acetylated version termed Neu5Ac (5-N-acetyl-neuraminic acid). Many bacteria are known to access sialic acid using sialidase enzymes. However, in humans a high proportion of sialic acid contains a second acetyl group attached via an O-group, i.e. chiefly O-acetylated Neu5,9Ac2 or Neu5,4Ac2. This diacetylated sialic acid is not cleaved efficiently by many sialidases and in order to access diacetylated sialic acid, some organisms produce sialate-O-acetylesterases that catalyse the removal of the second acetyl group. In the present study, we performed bioinformatic and biochemical characterization of a putative sialate-O-acetylesterase from T. forsythia (NanS), which contains two putative SGNH-hydrolase domains related to sialate-O-acetylesterases from a range of organisms. Purification of recombinant NanS revealed an esterase that has activity against Neu5,9Ac2 and its glycolyl form Neu5Gc,9Ac. Importantly, the enzyme did not remove acetyl groups positioned at the 4-O position (Neu5,4Ac2). In addition NanS can act upon complex N-glycans released from a glycoprotein [erythropoietin (EPO)], bovine submaxillary mucin and oral epithelial cell-bound glycans. When incubated with its cognate sialidase, NanS increased sialic acid release from mucin and oral epithelial cell surfaces, implying that this esterase improves sialic acid harvesting for this pathogen and potentially other members of the oral microbiome. In summary, we have characterized a novel sialate-O-acetylesterase that contributes to the sialobiology of this important human pathogen and has potential applications in the analysis of sialic acid diacetylation of biologics in the pharmaceutical industry.

  17. [The determination of sialic acid in cancer patients].

    Science.gov (United States)

    Correale, M; Abbate, I; Gargano, G; Catino, A; Musci, M D; Dragone, C D; De Lena, M

    1992-01-01

    The availability of a new rapid and reproducible laboratory test led to an easy dosage of sialic acid (AS) serum levels in neoplastic patients. This substance, involved in tumoral transformation and metastatic spread, has been evaluated in 278 neoplastic patients: 183 patients were affected by lymphoma (96 NHL and 87 HD), 60 by breast cancer and 35 by lung cancer. All groups of patients considered showed mean values of AS higher than healthy controls and the positive percentages, compared with cut-off levels, were respectively: NHL 71%, HD 70%, breast cancer 38%, lung cancer 89%. Even if the low specificity of this marker limits its clinical validity, AS, that seems related to clinical course of disease, could be useful in the monitoring of many neoplasms.

  18. Sialic acid changes in Dalton's lymphoma-bearing mice after cyclophosphamide and cisplatin treatment

    Directory of Open Access Journals (Sweden)

    Nicol B.M.

    2002-01-01

    Full Text Available Sialic acid changes in Dalton's lymphoma cells and other tissues of 10-12-week-old Swiss albino mice were investigated in relation to tumour growth in vivo and following cyclophosphamide (ip, 200 mg/kg body weight or cisplatin (ip, 8 mg/kg body weight treatment. Three to four animals of both sexes were used in each experimental group. The sialic acid level of tumour cells (0.88 µmol/g increased with tumour progression (1.44-1.59 µmol/g; P<=0.05 in mice. Sialic acid concentration in other tissues (liver, kidney, testes and brain also increased (~40, 10, 30 and 58%, respectively in the tumour-bearing hosts as compared with that in the respective tissues of normal mice. In vivo cyclophosphamide or cisplatin treatment resulted in an overall decrease of sialic acid contents in the tissues. Cyclophosphamide was more efficient in lowering tissue sialic acid than cisplatin (P<=0.01, ANOVA. It is suggested that sialic acid residues could be an important factor contributing to the manifestation of malignant properties in cancer cells in general and Dalton's lymphoma cells in particular. A significant decrease in the sialic acid content of Dalton's lymphoma cells after cisplatin or cyclophosphamide treatment may bring about specific changes in tumour cells which could be associated with tumour regression.

  19. Sialic acid catabolism confers a competitive advantage to pathogenic vibrio cholerae in the mouse intestine.

    Science.gov (United States)

    Almagro-Moreno, Salvador; Boyd, E Fidelma

    2009-09-01

    Sialic acids comprise a family of nine-carbon ketosugars that are ubiquitous on mammalian mucous membranes. However, sialic acids have a limited distribution among Bacteria and are confined mainly to pathogenic and commensal species. Vibrio pathogenicity island 2 (VPI-2), a 57-kb region found exclusively among pathogenic strains of Vibrio cholerae, contains a cluster of genes (nan-nag) putatively involved in the scavenging (nanH), transport (dctPQM), and catabolism (nanA, nanE, nanK, and nagA) of sialic acid. The capacity to utilize sialic acid as a carbon and energy source might confer an advantage to V. cholerae in the mucus-rich environment of the gut, where sialic acid availability is extensive. In this study, we show that V. cholerae can utilize sialic acid as a sole carbon source. We demonstrate that the genes involved in the utilization of sialic acid are located within the nan-nag region of VPI-2 by complementation of Escherichia coli mutants and gene knockouts in V. cholerae N16961. We show that nanH, dctP, nanA, and nanK are highly expressed in V. cholerae grown on sialic acid. By using the infant mouse model of infection, we show that V. cholerae DeltananA strain SAM1776 is defective in early intestinal colonization stages. In addition, SAM1776 shows a decrease in the competitive index in colonization-competition assays comparing the mutant strain with both O1 El Tor and classical strains. Our data indicate an important relationship between the catabolism of sialic acid and bacterial pathogenesis, stressing the relevance of the utilization of the resources found in the host's environment.

  20. Inhibitions of Several Antineoplastic Drugs on Serum Sialic Acid Levels in Mice Bearing Tumors

    OpenAIRE

    Lu, Da-Yong; Xu, Jing; Lu, Ting-Ren; Wu, Hong-Ying; Xu, Bin

    2012-01-01

    Six murine tumors, including ascetic tumors HepA, EC, P388 leukemia, S180 and solid tumor S180, and Lewis lung carcinoma, were employed in this work. The free sialic acid concentrations in both blood and ascites were measured in tumor-bearing mice. The results showed that the content of sialic acids in blood was increased in tumor growth and certain tumor types. Higher sialic acid content was observed in ascites than that present in blood. The influence of antineoplastic agents (vincristine, ...

  1. The distribution of tissue fibronectin and sialic acid in human breast cancer.

    Science.gov (United States)

    Süer, S; Baloğlu, H; Güngör, Z; Sönmez, H; Kökoğlu, E

    1998-06-01

    Our findings indicate that sialic acid and fibronectin levels in breast tumors are higher than those in normal tissues. The mean tissue fibronectin and sialic acid concentrations for patients with breast cancer were 30.90 +/- 9.68 microg/mg protein and 21.60 +/- 9.35 microg/mg protein, respectively, and for normal controls were 12.47 +/- 5.69 microg/mg protein, respectively. Tissue fibronectin and sialic acid can be important markers for human breast cancer.

  2. Analysis of Sialic acid and Sphingomyelin of Brain of Mice by Using Spectrophotometer and Hplc

    OpenAIRE

    Siti Suryaningsih

    2012-01-01

    Sialic acid is an important component of brain which is needed to form ganglioside molecule of brain’s membrane, while sphingomyelin has a role in myelination of central nervous system during the growth development of babies. The aims of this research were to analyze the sialic acid and sphingomyelin contents of the brain of mice and compared with their contents in the ration of mice. The study was carried out in three phases as follows: i.e., ration formulation, analysis of sialic acid and s...

  3. O-acetylated sialic acids in gangliosides from pig spleen lymphocytes.

    Science.gov (United States)

    Hueso, P; Cabezas, J A; Reglero, A

    1988-01-01

    The sialic acid content of gangliosides from pig spleen lymphocytes was studied by thin-layer chromatography. N-glycolylneuraminic acid and N-acetylneuraminic acid were detected for the first time in this material as the major sialic acids. In addition, two other sialic acids, tentatively designated O-acetylated sialic acids, according to their RF values on cellulose plates, were also found. We have detected several gangliosides showing a retarded migration pattern in two dimensional thin-layer chromatography with an intermediate ammonia treatment. One of these gangliosides could be an O-acetylated derivative of the disialoganglioside GD3, since after de-O-acetyation it co-migrates with GD3. Another ganglioside co-migrated with GM2 before the alkaline treatment; however, after the treatment it was also retarded and co-migrates with GD3.

  4. Rapid regulation of sialidase activity in response to neural activity and sialic acid removal during memory processing in rat hippocampus.

    Science.gov (United States)

    Minami, Akira; Meguro, Yuko; Ishibashi, Sayaka; Ishii, Ami; Shiratori, Mako; Sai, Saki; Horii, Yuuki; Shimizu, Hirotaka; Fukumoto, Hokuto; Shimba, Sumika; Taguchi, Risa; Takahashi, Tadanobu; Otsubo, Tadamune; Ikeda, Kiyoshi; Suzuki, Takashi

    2017-04-07

    Sialidase cleaves sialic acids on the extracellular cell surface as well as inside the cell and is necessary for normal long-term potentiation (LTP) at mossy fiber-CA3 pyramidal cell synapses and for hippocampus-dependent spatial memory. Here, we investigated in detail the role of sialidase in memory processing. Sialidase activity measured with 4-methylumbelliferyl-α-d-N-acetylneuraminic acid (4MU-Neu5Ac) or 5-bromo-4-chloroindol-3-yl-α-d-N-acetylneuraminic acid (X-Neu5Ac) and Fast Red Violet LB was increased by high-K(+)-induced membrane depolarization. Sialidase activity was also increased by chemical LTP induction with forskolin and activation of BDNF signaling, non-NMDA receptors, or NMDA receptors. The increase in sialidase activity with neural excitation appears to be caused not by secreted sialidase or by an increase in sialidase expression but by a change in the subcellular localization of sialidase. Astrocytes as well as neurons are also involved in the neural activity-dependent increase in sialidase activity. Sialidase activity visualized with a benzothiazolylphenol-based sialic acid derivative (BTP3-Neu5Ac), a highly sensitive histochemical imaging probe for sialidase activity, at the CA3 stratum lucidum of rat acute hippocampal slices was immediately increased in response to LTP-inducible high-frequency stimulation on a time scale of seconds. To obtain direct evidence for sialic acid removal on the extracellular cell surface during neural excitation, the extracellular free sialic acid level in the hippocampus was monitored using in vivo microdialysis. The free sialic acid level was increased by high-K(+)-induced membrane depolarization. Desialylation also occurred during hippocampus-dependent memory formation in a contextual fear-conditioning paradigm. Our results show that neural activity-dependent desialylation by sialidase may be involved in hippocampal memory processing. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Recombinant sialidase NanA (rNanA) cleaves α2-3 linked sialic acid of host cell surface N-linked glycoprotein to promote Edwardsiella tarda infection.

    Science.gov (United States)

    Chigwechokha, Petros Kingstone; Tabata, Mutsumi; Shinyoshi, Sayaka; Oishi, Kazuki; Araki, Kyosuke; Komatsu, Masaharu; Itakura, Takao; Shiozaki, Kazuhiro

    2015-11-01

    Edwardsiella tarda is one of the major pathogenic bacteria affecting both marine and freshwater fish species. Sialidase NanA expressed endogenously in E. tarda is glycosidase removing sialic acids from glycoconjugates. Recently, the relationship of NanA sialidase activity to E. tarda infection has been reported, however, the mechanism with which sialidase NanA aids the pathogenicity of E. tarda remained unclear. Here, we comprehensively determined the biochemical properties of NanA towards various substrates in vitro to provide novel insights on the potential NanA target molecule at the host cell. GAKS cell pretreated with recombinant NanA showed increased susceptibility to E. tarda infection. Moreover, sialidase inhibitor treated E. tarda showed a significantly reduced ability to infect GAKS cells. These results indicate that NanA-induced desialylation of cell surface glycoconjugates is essential for the initial step of E. tarda infection. Among the natural substrates, NanA exhibited the highest activity towards 3-sialyllactose, α2-3 linked sialic acid carrying sialoglycoconjugates. Supporting this finding, intact GAKS cell membrane exposed to recombinant NanA showed changes of glycoconjugates only in α2-3 sialo-linked glycoproteins, but not in glycolipids and α2-6 sialo-linked glycoproteins. Lectin staining of cell surface glycoprotein provided further evidence that α2-3 sialo-linkage of the N-linked glycoproteins was the most plausible target of NanA sialidase. To confirm the significance of α2-3 sialo-linkage desialylation for E. tarda infection, HeLa cells which possessed lower amount of α2-3 sialo-linkage glycoprotein were used for infection experiment along with GAKS cells. As a result, infection of HeLa cells by E. tarda was significantly reduced when compared to GAKS cells. Furthermore, E. tarda infection was significantly inhibited by mannose pretreatment suggesting that the bacterium potentially recognizes and binds to mannose or mannose containing

  6. Membrane-enclosed multienzyme (MEME) synthesis of 2,7-anhydro-sialic acid derivatives.

    Science.gov (United States)

    Monestier, Marie; Latousakis, Dimitrios; Bell, Andrew; Tribolo, Sandra; Tailford, Louise E; Colquhoun, Ian J; Le Gall, Gwenaelle; Yu, Hai; Chen, Xi; Rejzek, Martin; Dedola, Simone; Field, Robert A; Juge, Nathalie

    2017-08-19

    Naturally occurring 2,7-anhydro-alpha-N-acetylneuraminic acid (2,7-anhydro-Neu5Ac) is a transglycosylation product of bacterial intramolecular trans-sialidases (IT-sialidases). A facile one-pot two-enzyme approach has been established for the synthesis of 2,7-anhydro-sialic acid derivatives including those containing different sialic acid forms such as Neu5Ac and N-glycolylneuraminic acid (Neu5Gc). The approach is based on the use of Ruminoccocus gnavus IT-sialidase for the release of 2,7-anhydro-sialic acid from glycoproteins, and the conversion of free sialic acid by a sialic acid aldolase. This synthetic method, which is based on a membrane-enclosed enzymatic synthesis, can be performed on a preparative scale. Using fetuin as a substrate, high-yield and cost-effective production of 2,7-anhydro-Neu5Ac was obtained to high-purity. This method was also applied to the synthesis of 2,7-anhydro-Neu5Gc. The membrane-enclosed multienzyme (MEME) strategy reported here provides an efficient approach to produce a variety of sialic acid derivatives. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Plasma lipid-bound sialic acid and carcinoembryonic antigen in cancer patients.

    Science.gov (United States)

    Dnistrian, A M; Schwartz, M K

    1981-10-01

    We evaluated lipid-bound sialic acid as a "marker" in cancer patients and assessed the individual and combined value of lipid-bound sialic acid and carcinoembryonic antigen determinations in these patients. Plasma was sampled from 62 normal subjects and 125 cancer patients. Lipid-bound sialic acid was determined by the resorcinol method after total lipid extraction and isolation of the sialolipid fraction from plasma. Neither marker was increased in many breast cancer patients. Carcinoembryonic antigen was increased more commonly and to a greater degree in colon cancer patients and seems to be the preferred marker. Both markers were increased in lung cancer patients and their combined evaluation improved the rate of detection. Lipid-bound sialic acid was increased in more patients with leukemias, lymphomas, Hodgkin's disease, and melanomas, suggesting that it may be a useful biochemical marker in these types of cancer.

  8. Serum sialic acid and glycoprotein levels in some Libyan cancer patients.

    Science.gov (United States)

    Balo, N N; Ishaq, M

    1991-01-01

    Sialic acid is a common conjugate of some serum glycoproteins and glycolipids. Elevated levels of serum sialic acid and alterations in serum glycoproteins have been observed in certain types of cancer. In this study sialic acid concentration in the sera of patients with various types of cancer was determined. In addition to this, serum glycoproteins were also analysed by electrophoretic method. Our results indicate that serum sialic acid levels are generally raised in all types of cancer studied. This increase was more pronounced in case of lung, bronchogenic, intestinal and breast cancer. Some alterations in the serum glycoprotein profiles were also observed, particularly in bronchogenic and gall bladder cancer where an additional band in the low molecular weight region was present and in lung, breast and lymphoma where a band in the middle molecular weight region was found missing when compared with normals.

  9. Clinical usefulness of alterations in sialic acid, sialyl transferase and sialoproteins in breast cancer

    OpenAIRE

    Raval, G. N.; Parekh, L. J.; Patel, D D; Jha, F. P.; Sainger, R. N.; Patel, P. S.

    2004-01-01

    Sialic acid, the end moieties of the carbohydrate chains are biologically important and essential for functions of glycoconjugates and are reported to be altered in cancer patients. Two hundred and twenty five breast cancer (BC) patients, 100 patients with benign breast disease (BBD) and 100 healthy females (controls) were enrolled for the study. Eight hundred and twenty four follow-up samples of 225 breast carcinoma patients were also evaluated. The association of sialic acid forms, sialyltr...

  10. The evaluation of serum total sialic acid and lipid-bound sialic acid levels in chronically exposed rats to 7,12-dimethylbenz(a)anthracene and fluoride

    Science.gov (United States)

    Oto, Gokhan; Ekin, Suat; Uyar, Hasan; Ozdemir, Hulya; Yıldız, Damla; Karakuş, Yagmur

    2017-04-01

    In this study, changes in serum total sialic acid (TSA) and lipid-bound sialic acid (LSA) levels were examined in chronically exposed rats to 7,12-dimethylbenz(a)anthracene (DMBA) and fluoride. This study demonstrated that the TSA, LSA levels increased more in DMBA-treated groups compared to the fluoride treated groups. The result obtained has shown that the harmful effect of DMBA which is also causing more cell membrane damage on human and animal health should be taken into consideration.

  11. Storage material from urine and tissues in the nephropathic phenotype of infantile sialic acid storage disease.

    Science.gov (United States)

    Paschke, E; Gruber, W; Ring, E; Sperl, W

    1992-01-01

    We analysed urine and tissue specimens from two nephrotic infantile sialic acid storage disease patients (nISSD) for free and bound sialic acids in comparison to non-nephrotic ISSD patients (ISSD), patients with minimal change nephrosis (nControl) and normal controls (Control). No differences in the excretion of urinary free sialic acid could be detected between ISSD and nISSD urines. Sialyloligosaccharide fractions were only slightly elevated and of apparently normal composition. Owing to glomerular dysfunction, measurable quantities of protein-bound sialic acids were present in nISSD and nControl. In nISSD tissues, free sialic acid was elevated 18-100-fold above control and 3-12-fold above Niemann-Pick A (NPA) samples. The storage of membrane-bound sialic acid was slightly increased compared to control tissues, but equal to those from NPA, thus reflecting an unspecific increase of membranes due to lysosomal storage. According to these results no major biochemical differences were detectable between ISSD and nISSD. The nephrotic syndrome in nISSD could not be related to a general deficit in the sialylation of glycoproteins. Nevertheless, a cell membrane-specific alteration in sialoglycoproteins of glomerular cells might still be possible.

  12. Sialic acids in squamous cell carcinoma of the head and neck

    Directory of Open Access Journals (Sweden)

    Izabela Bronikowska

    2016-12-01

    Full Text Available Altered glycosylation is a universal characteristic of cancer cells, and various types of glycan structures are well‑known markers of tumor progression and invasion. The present article discusses this aspect of the role of sialic acid, biosynthesis of sialylglycoconjugates and the genetic basis of its disorder, as well as the effects and the correlation between altered sialylation and clinical prognosis in head and neck squamous cell carcinoma (HNSCC.Only a few studies concerning the level of sialic acid in head and neck tumors have been conducted so far. The conclusions of the published reports dedicated to that problem confirm the presence of elevated levels of total sialic acid in these tumors. The authors do not always agree with the level of free or associated form of sialic acid correlated with tumor size, severity of the condition, and lymph nodes. Comparing the progress that has been made in the diagnosis and treatment of other cancers thanks to extensive work on the role of sialic acids, we come to the conclusion that only further detailed studies of this subject in relation to HNSCC are able to answer the question whether the extent of glycoforms of sialic acid may act as a tumor marker or target of immunotherapy.

  13. Plasma lipid-bound sialic acid alterations in neoplastic diseases.

    Science.gov (United States)

    Dwivedi, C; Dixit, M; Hardy, R E

    1990-01-15

    Plasma lipid-bound sialic acid (LSA) was assayed in normal volunteers, patients with non-malignant diseases, and a variety of cancer patients. Mean plasma LSA in 50 normal volunteers, 16 patients with non-malignant diseases, 54 breast cancer, 17 lung cancer, 15 colon cancer, 7 ovarian cancer, 5 prostate cancer, 4 leukemia, 4 gastrointestinal, 3 thyroid cancer, 3 pancreas cancer and 2 adrenal cancer patients were 17.7, 23.2, 58, 85, 56.7, 46.2, 56.7, 53.3, 31.1, 33.2 and 119.5 mg/dl, respectively. None of the normal volunteers had elevated plasma LSA values. Plasma LSA level was not significantly different in male and female volunteers. Two out of 114 different cancer patients had plasma LSA levels within normal range exhibiting 98.2% sensitivity of the assay. Plasma LSA, which is relatively simple to assay, may be used as a tumor marker in wide variety of neoplastic diseases.

  14. Sialic Acid-Responsive Polymeric Interface Material: From Molecular Recognition to Macroscopic Property Switching

    Science.gov (United States)

    Xiong, Yuting; Jiang, Ge; Li, Minmin; Qing, Guangyan; Li, Xiuling; Liang, Xinmiao; Sun, Taolei

    2017-01-01

    Biological systems that utilize multiple weak non-covalent interactions and hierarchical assemblies to achieve various bio-functions bring much inspiration for the design of artificial biomaterials. However, it remains a big challenge to correlate underlying biomolecule interactions with macroscopic level of materials, for example, recognizing such weak interaction, further transforming it into regulating material’s macroscopic property and contributing to some new bio-applications. Here we designed a novel smart polymer based on polyacrylamide (PAM) grafted with lactose units (PAM-g-lactose0.11), and reported carbohydrate-carbohydrate interaction (CCI)-promoted macroscopic properties switching on this smart polymer surface. Detailed investigations indicated that the binding of sialic acid molecules with the grafted lactose units via the CCIs induced conformational transformation of the polymer chains, further resulted in remarkable and reversible switching in surface topography, wettability and stiffness. With these excellent recognition and response capacities towards sialic acid, the PAM-g-lactose0.11 further facilitated good selectivity, strong anti-interference and high adsorption capacity in the capture of sialylated glycopeptides (important biomarkers for cancers). This work provides some enlightenment for the development of biointerface materials with tunable property, as well as high-performance glycopeptide enrichment materials. PMID:28084463

  15. Sialic Acid-Responsive Polymeric Interface Material: From Molecular Recognition to Macroscopic Property Switching

    Science.gov (United States)

    Xiong, Yuting; Jiang, Ge; Li, Minmin; Qing, Guangyan; Li, Xiuling; Liang, Xinmiao; Sun, Taolei

    2017-01-01

    Biological systems that utilize multiple weak non-covalent interactions and hierarchical assemblies to achieve various bio-functions bring much inspiration for the design of artificial biomaterials. However, it remains a big challenge to correlate underlying biomolecule interactions with macroscopic level of materials, for example, recognizing such weak interaction, further transforming it into regulating material’s macroscopic property and contributing to some new bio-applications. Here we designed a novel smart polymer based on polyacrylamide (PAM) grafted with lactose units (PAM-g-lactose0.11), and reported carbohydrate-carbohydrate interaction (CCI)-promoted macroscopic properties switching on this smart polymer surface. Detailed investigations indicated that the binding of sialic acid molecules with the grafted lactose units via the CCIs induced conformational transformation of the polymer chains, further resulted in remarkable and reversible switching in surface topography, wettability and stiffness. With these excellent recognition and response capacities towards sialic acid, the PAM-g-lactose0.11 further facilitated good selectivity, strong anti-interference and high adsorption capacity in the capture of sialylated glycopeptides (important biomarkers for cancers). This work provides some enlightenment for the development of biointerface materials with tunable property, as well as high-performance glycopeptide enrichment materials.

  16. Estimation of salivary sialic acid in oral premalignancy and oral squamous cell carcinoma

    Directory of Open Access Journals (Sweden)

    Vishakha Chaudhari

    2016-01-01

    Full Text Available Aims: Oral cancer is the most life-threatening disease of oral tissues. In societies where the incidence of oral cancer is high, clinically recognizable premalignant lesions are particularly common. Diagnosing oral cancers at an early stage is critical in improving the survival rate and reducing the morbidity associated with the disease. Alterations in the sialic acid levels in cancer patients have stimulated interest in this sugar residue as a possible tumor marker. Settings and Design: The purpose of this study was to estimate the salivary sialic acid levels in patients with oral premalignancy and squamous cell carcinoma and to correlate it with their grades to develop a cost-effective and noninvasive diagnostic parameter. Materials and Methods: Unstimulated whole saliva was collected from the groups under study and subjected to biochemical analysis for determination of sialic acid levels. Statistical Analysis Used: The salivary sialic acid levels were correlated with the clinical stage and histological grade by one-way ANOVA (SPSS software version 15. Results: Salivary sialic acid was elevated in oral squamous cell carcinoma (OSCC compared to oral premalignancy and control group. A statistically significant correlation was observed between the grades of squamous cell carcinoma, grades of dysplasia in premalignancy, and sialic acid level. Conclusion and Clinical Significance: Evaluation of salivary sialic acid levels in premalignant and malignant lesions can serve as a screening tool. The mortality and morbidity of OSCC can be reduced if the lesions are diagnosed in early precancerous states using such noninvasive diagnostic methods for screening and monitoring of the population.

  17. Porcine milk oligosaccharides and sialic acid concentrations vary throughout lactation

    Directory of Open Access Journals (Sweden)

    Austin T Mudd

    2016-09-01

    Full Text Available Background: Milk oligosaccharides (OS are bioactive components known to influence neonatal development. These compounds have specific physiological functions acting as prebiotics, immune system modulators, and enhancing intestine and brain development. Objectives: The pig is a commonly used model for studying human nutrition, and there is interest in characterizing and quantifying OS composition of porcine milk across lactation. In this study, we hypothesized that OS and sialic acid (SA composition of porcine milk would be influenced by stage of lactation. Methods: Up to 250 ml of milk was collected from 7 sows at each of three time points: d 0 (colostrum, d 7-9 (mature, and d 17-19 (weaning. Colostrum was collected within 6 h of farrowing and three-day intervals were used for mature and weaning milk to ensure representative sampling. Milk samples were analyzed for OS profiles by Nano LC Chip QTOF MS, OS concentrations via HPAEC-PAD, and SA (total and free was assessed by enzymatic reaction fluorescence detection.Results: Sixty unique OS were identified in porcine milk. Neutral OS were the most abundant at each lactation stage (69-81%, followed by acidic-sialylated OS (16-29% and neutral-fucosylated OS (2-4%. As lactation progressed, acidic OS decreased (P < 0.05, whereas neutral-fucosylated and neutral OS increased (P < 0.05 throughout lactation. Six OS were present in all samples analyzed across lactation (LDFH-I, 2´-FL, LNFP-I, LNnH, 3-Hex, 3´-SL, while LDFT was present only in colostrum samples. Analysis of individual OS concentrations indicated differences (P < 0.05 between days 0 and 7. Conversely, between days 7 and 18, OS concentrations remained stable with only LNnH and LNDFH-I decreasing (P < 0.05 over this period. Analysis of free SA indicated a decrease (P < 0.05 as lactation progressed, while bound and total SA increased (P < 0.05 across lactation. Conclusions: The present data suggest that while porcine milk OS profiles and

  18. Bacterial periplasmic sialic acid-binding proteins exhibit a conserved binding site

    Energy Technology Data Exchange (ETDEWEB)

    Gangi Setty, Thanuja [Institute for Stem Cell Biology and Regenerative Medicine, NCBS Campus, GKVK Post, Bangalore, Karnataka 560 065 (India); Cho, Christine [Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109 (United States); Govindappa, Sowmya [Institute for Stem Cell Biology and Regenerative Medicine, NCBS Campus, GKVK Post, Bangalore, Karnataka 560 065 (India); Apicella, Michael A. [Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109 (United States); Ramaswamy, S., E-mail: ramas@instem.res.in [Institute for Stem Cell Biology and Regenerative Medicine, NCBS Campus, GKVK Post, Bangalore, Karnataka 560 065 (India)

    2014-07-01

    Structure–function studies of sialic acid-binding proteins from F. nucleatum, P. multocida, V. cholerae and H. influenzae reveal a conserved network of hydrogen bonds involved in conformational change on ligand binding. Sialic acids are a family of related nine-carbon sugar acids that play important roles in both eukaryotes and prokaryotes. These sialic acids are incorporated/decorated onto lipooligosaccharides as terminal sugars in multiple bacteria to evade the host immune system. Many pathogenic bacteria scavenge sialic acids from their host and use them for molecular mimicry. The first step of this process is the transport of sialic acid to the cytoplasm, which often takes place using a tripartite ATP-independent transport system consisting of a periplasmic binding protein and a membrane transporter. In this paper, the structural characterization of periplasmic binding proteins from the pathogenic bacteria Fusobacterium nucleatum, Pasteurella multocida and Vibrio cholerae and their thermodynamic characterization are reported. The binding affinities of several mutations in the Neu5Ac binding site of the Haemophilus influenzae protein are also reported. The structure and the thermodynamics of the binding of sugars suggest that all of these proteins have a very well conserved binding pocket and similar binding affinities. A significant conformational change occurs when these proteins bind the sugar. While the C1 carboxylate has been identified as the primary binding site, a second conserved hydrogen-bonding network is involved in the initiation and stabilization of the conformational states.

  19. Adaptation of Influenza A Viruses to Cells Expressing Low Levels of Sialic Acid Leads to Loss of Neuraminidase Activity

    OpenAIRE

    2001-01-01

    Influenza A viruses possess two virion surface proteins, hemagglutinin (HA) and neuraminidase (NA). The HA binds to sialyloligosaccharide viral receptors, while the NA removes sialic acids from the host cell and viral sialyloligosaccarides. Alterations of the HA occur during adaptation of influenza viruses to new host species, as in the 1957 and 1968 influenza pandemics. To gain a better understanding of the contributions of the HA and possibly the NA to this process, we generated cell lines ...

  20. Histochemical properties of sialic acids and antimicrobial substances in canine anal glands

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    T. Nara

    2011-09-01

    Full Text Available The functional properties of sialic acids appear to be manifold. Additionally, antimicrobial substances serve as a non-specific defense against microorganisms. In this study, therefore, the localization of sialic acids and antimicrobial substances in the anal glands of dog was studied by sialoglycoconjugate histochemistry and immunohistochemistry. The secretory epithelium, luminal secretions and excretory ducts exhibited high levels of sialoglycoconjugates that terminated in Siaα2-6Gal/GalNAc or Siaα2-3Gal1-4GlcNAc. Additionally, O-acetylated sialic acids were detectable in these glandular structures. Antimicrobial substances, such as lysozyme, immunoglobulin A (IgA, lactoferrin and the peptide group of β-defensins, were also demonstrated as products of the anal glands. The results obtained are discussed with regard to the functional significance of the anal glands. These secretory products may create a defensive barrier against microbial invasion at the anal mucosa.

  1. Total and lipid-bound serum sialic acid in benign and malignant breast disease.

    Science.gov (United States)

    Romppanen, J; Eskelinen, M; Tikanoja, S; Mononen, I

    1997-01-01

    Elevation in the total sialic acid (TSA), TSA/total protein (TSA/TP) and lipid-bound sialic acid (LASA) concentration in serum occurs in breast cancer and we have studied the applicability of the assays in classification of undefined breast tumors. Sialic acid was determined by HPLC and the statistical evaluation included the receiver operating characteristic (ROC) and Youden's index analyses. In cancer patients, the serum LASA and TSA concentration was significantly higher (p breast cancer and benign breast disease and at the specificity level of 0.95 the corresponding sensitivities were 0.32 (TSA), 0.14 (TSA/TP) and 0.23 (LASA). The results indicate that both breast cancer and benign breast disease cause elevation of TSA, TSA/TP and LASA values in serum and do not provide reliable classification of undefined breast tumors.

  2. Sialic acid mediates the initial binding of positively charged inorganic particles to alveolar macrophage membranes.

    Science.gov (United States)

    Gallagher, J E; George, G; Brody, A R

    1987-06-01

    Pulmonary macrophages phagocytize inhaled particles and are postulated to play a role in the development of pulmonary interstitial fibrogenesis. The basic biologic mechanisms through which inhaled particles bind to macrophage membranes and subsequently are phagocytized remain unclear. We hypothesize that positively charged particles bind to negatively charged sialic acid (SA) residues on macrophage membranes. Alveolar Macrophages (AM) were collected by saline lavage from normal rat lungs. The cells adhered to plastic coverslips in serum-free phosphate buffered saline at 37 degrees C for 45 min and then were maintained at 4 degrees C for the binding experiments. Even distribution of SA groups on AM surfaces was demonstrated by scanning electron microscopy of wheat germ agglutinin (WGA) conjugated to 50 nm gold spheres. The WGA is a lectin that binds specifically to sialic acid, and pretreatment of AM with this lectin prevented the binding of positively charged carbonyl iron (C-Fe) spheres, aluminum (Al) spheres, and chrysotile asbestos fibers to AM surfaces. Limulus protein, another lectin with binding specificity for SA, similarly blocked the binding of positively charged spheres and chrysotile asbestos fibers but not negatively charged glass spheres or crocidolite asbestos fibers. Con A and ricin, lectins that bind to mannose and galactose residues, respectively, did not block particle binding. When both positively charged iron spheres and negatively charged glass spheres were prebound to AM membranes, subsequent treatment with WGA displaced only the positively charged spheres from macrophage surfaces. Con A and ricin had no effect on prebound positively charged C-Fe and Al spheres.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Evaluation of salivary sialic acid, total protein, and total sugar in oral cancer: A preliminary report

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    Sanjay P

    2008-01-01

    Full Text Available Aim: Detection of cancer at the early stage is of utmost importance to decrease the morbidity and mortality of the disease. Apart from the conventional biopsy, noninvasive methods like analysis of saliva may provide a cost-effective approach for screening a large population. Thus, this study aimed to estimate salivary levels of sialic acid, total protein, and total sugar in the oral cancer patients and in healthy control group to evaluate their role in diagnosis and prognosis of oral cancer. Study Design: Unstimulated whole saliva samples were collected from 30 healthy controls (Group I and 30 squamous cell carcinoma patients (group II. Estimations of salivary levels of sialic acid, total protein, and total sugar were performed. This was correlated histopathologically with the grades of carcinoma. Statistical Analysis and Results: The Student′s ′ t ′ test and multivariate regression analysis were performed. The results showed that salivary levels of total protein, total sugar, protein-bound sialic acid, and free sialic acid were significantly higher in oral cancer patients compared to those of normal healthy controls ( P values in all the results were less than 0.001. The salivary free sialic acid levels were found to be significantly higher in well-differentiated squamous cell carcinoma than in moderately differentiated carcinoma ( P < 0.001. However, protein-bound sialic acid, total proteins, and total sugars did not show any statistical significance between well and moderately differentiated carcinomas. Conclusion: Biochemical analysis of saliva can be used in early detection of cancer and is best correlated with histopathological degree of squamous cell carcinoma.

  4. Relationship between Sialic acid and metabolic variables in Indian type 2 diabetic patients

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    Nayak B Shivananda

    2005-08-01

    Full Text Available Abstract Background Plasma sialic acid is a marker of the acute phase response. Objective is to study the relationship between sialic acid relationship with metabolic variables in Indian type 2 diabetes with and without microvascular complications. Research design and Methods Fasting Venous blood samples were taken from 200 subjects of which 50 were of diabetes mellitus (DM and nephropathy patients, 50 patients with type 2 diabetes and retinopathy, 50 patients with type 2 diabetes without any complications and 50 healthy individuals without diabetes. The Indian subject's aged 15–60 years with type 2 diabetes were recruited for the study. Simultaneously urine samples were also collected from each of the subjects. All the blood samples were analyzed for total cholesterol, triglyceride (TG, low-density lipoprotein (LDL, high-density lipoprotein (HDL, fasting and postprandial glucose on fully automated analyzer. Serum and urine sialic acid along with microalbumin levels were also estimated. Results There was a significantly increasing trend of plasma and urine sialic acid with severity of nephropathy (P 1c, serum triglyceride and cholesterol concentrations, waist-to-hip ratio and hypertension. Significant correlations were found between sialic acid concentration and cardiovascular risk factors like LDL and TG in the diabetic subjects. Conclusion The main finding of this study is that elevated serum and urinary sialic acid and microalbumin concentrations were strongly related to the presence of microvascular complications like diabetic nephropathy and retinopathy and cardiovascular risk factors in Indian type 2 diabetic subjects. Further study of acute-phase response markers and mediators as indicators or predictors of diabetic microvascular complications is therefore justified.

  5. Adaptation of influenza A viruses to cells expressing low levels of sialic acid leads to loss of neuraminidase activity.

    Science.gov (United States)

    Hughes, M T; McGregor, M; Suzuki, T; Suzuki, Y; Kawaoka, Y

    2001-04-01

    Influenza A viruses possess two virion surface proteins, hemagglutinin (HA) and neuraminidase (NA). The HA binds to sialyloligosaccharide viral receptors, while the NA removes sialic acids from the host cell and viral sialyloligosaccarides. Alterations of the HA occur during adaptation of influenza viruses to new host species, as in the 1957 and 1968 influenza pandemics. To gain a better understanding of the contributions of the HA and possibly the NA to this process, we generated cell lines expressing reduced levels of the influenza virus receptor determinant, sialic acid, by selecting Madin-Darby canine kidney cells resistant to a lectin specific for sialic acid linked to galactose by alpha(2-3) or alpha(2-6) linkages. One of these cell lines had less than 1/10 as much N-acetylneuraminic acid as its parent cell line. When serially passaged in this cell line, human H3N2 viruses lost sialidase activity due to a large internal deletion in the NA gene, without alteration of the HA gene. These findings indicate that NA mutations can contribute to the adaptation of influenza A virus to new host environments and hence may play a role in the transmission of virus across species.

  6. A sialic acid assay in isolation and purification of bovine k-casein glycomacropeptide: a review.

    Science.gov (United States)

    Nakano, Takuo; Ozimek, Lech

    2014-01-01

    Sialic acid is a carbohydrate moiety of k-casein glycomacropeptide (GMP), which is a 64 amino acid residue C-terminal sialylated phosphorylated glycopeptide released from k-casein by the action of chymosin during cheese making. GMP lacks aromatic amino acids including phenylalanine, tyrosine, and tryptophan. Because of its unique amino acid composition and various biological activities, GMP is thought to be a potential ingredient for dietetic foods (e.g., a food for PKU patients) and pharmaceuticals. Thus, increased attention has been given to the development of techniques to purify GMP. In this review, techniques of GMP purification described in patents and scientific research papers were introduced. A sialic acid assay is the important method to track GMP isolation and purification processes, for which the thiobarbituric acid reaction with 1-propanol as a chromophore extracting solvent is an inexpensive, practical and specific technique. Sephacryl S-200 gel filtration chromatography, cellulose acetate electrophoresis, and sodium dodecyl sulfate polyacrylamide gel electrophoresis are the major techniques to identify sialic acid specific to GMP. Sephacryl S-200 chromatography and cellulose acetate electrophoresis are also used to detect GMP sialic acid in whey pearmeate and whey added commercial margarine samples. Future research includes development of an economical industrial scale method to produce high purity GMP.

  7. Natural and synthetic sialic acid-containing inhibitors of influenza virus receptor binding.

    Science.gov (United States)

    Matrosovich, Mikhail; Klenk, Hans-Dieter

    2003-01-01

    Influenza viruses attach to susceptible cells via multivalent interactions of their haemagglutinins with sialyloligosaccharide moieties of cellular glycoconjugates. Soluble macromolecules containing sialic acid from animal sera and mucosal fluids can act as decoy receptors and competitively inhibit virus-mediated haemagglutination and infection. Although a role for these natural inhibitors in the innate anti-influenza immunity is still not clear, studies are in progress on the design of synthetic sialic acid-containing inhibitors of receptor binding which could be used as anti-influenza drugs.

  8. Lipid-associated sialic acid levels in human breast cyst fluids.

    Science.gov (United States)

    Mannello, F; Bocchiotti, G; Troccoli, R; Gazzanelli, G

    1992-01-01

    Benign mammary gross cystic disease is the most common breast lesion. Women with apocrine changes of epithelium lining the cysts are at higher risk for developing breast cancer than the normal female population. Sialic acid has drawn considerable interest because of carbohydrate aberrations in malignant cells. The current investigation determined the concentrations of lipid-associated sialic acid (LASA) in 62 breast cyst fluids and sera. Data analyses show a significant increase in the mean values of LASA in metabolically active apocrine cysts when compared to the cysts with Na+/K+ > 3 (flattened cysts) (p breast cancer.

  9. H7N9 influenza viruses interact preferentially with α2,3-linked sialic acids and bind weakly to α2,6-linked sialic acids.

    Science.gov (United States)

    Ramos, Irene; Krammer, Florian; Hai, Rong; Aguilera, Domingo; Bernal-Rubio, Dabeiba; Steel, John; García-Sastre, Adolfo; Fernandez-Sesma, Ana

    2013-11-01

    The recent human outbreak of H7N9 avian influenza A virus has caused worldwide concerns. Receptor binding specificity is critical for viral pathogenicity, and still not thoroughly studied for this emerging virus. Here, we evaluated the receptor specificity of the haemagglutinin (HA) of two human H7N9 isolates (A/Shanghai/1/13 and A/Anhui/1/13) through a solid-phase binding assay and a flow cytometry-based assay. In addition, we compared it with those from several HAs from human and avian influenza viruses. We observed that the HAs from the novel H7 isolates strongly interacted with α2,3-linked sialic acids. Importantly, they also showed low levels of binding to α2,6-linked sialic acids, but significantly higher than other avian H7s.

  10. Artificial and Natural Sialic Acid Precursors Influence the Angiogenic Capacity of Human Umbilical Vein Endothelial Cells

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    Sebastian P. Galuska

    2013-02-01

    Full Text Available N-acetylneuraminic acid (Neu5Ac represents the most common terminal carbohydrate residue in many mammalian glycoconjugates and is directly involved in a number of different physiological as well as pathological cellular processes. Endogenous sialic acids derive from the biosynthetic precursor molecule N-acetyl-D-mannosamine (ManNAc. Interestingly, N-acyl-analogues of D-mannosamine (ManN can also be incorporated and converted into corresponding artificial sialic acids by eukaryotic cells. Within this study, we optimized a protocol for the chemical synthesis of various peracetylated ManN derivatives resulting in yields of approximately 100%. Correct molecular structures of the obtained products ManNAc, N-propanoyl-ManN (ManNProp and N-butyl-ManN (ManNBut were verified by GC-, ESI-MS- and NMR-analyses. By applying these substances to human umbilical vein endothelial cells (HUVECs, we could show that each derivative was metabolized to the corresponding N-acylneuraminic acid variant and subsequently incorporated into nascent glycoproteins. To investigate whether natural and/or artificial sialic acid precursors are able to modulate the angiogenic capacity of HUVECs, a spheroid assay was performed. By this means, an increase in total capillary length has been observed when cells incorporated N-butylneuraminic acid (Neu5But into their glycoconjugates. In contrast, the natural precursor ManNAc inhibited the growth of capillaries. Thus, sialic acid precursors may represent useful agents to modulate blood vessel formation.

  11. Total sialic acid, total protein and total sugar levels in serum and saliva of oral squamous cell carcinoma patients: A case control study

    Directory of Open Access Journals (Sweden)

    Nidhi Dhakar

    2013-01-01

    Conclusion: The present study showed a significant increase in serum sialic acid, salivary sialic acid and serum protein from control to OSCC and suggests that these markers may be reliable in diagnosis and predicting prognosis.

  12. Sialic acid transporter NanT participates in Tannerella forsythia biofilm formation and survival on epithelial cells.

    Science.gov (United States)

    Honma, Kiyonobu; Ruscitto, Angela; Frey, Andrew M; Stafford, Graham P; Sharma, Ashu

    2016-05-01

    Tannerella forsythia is a periodontal pathogen implicated in periodontitis. This gram-negative pathogen depends on exogenous peptidoglycan amino sugar N-acetylmuramic acid (NAM) for growth. In the biofilm state the bacterium can utilize sialic acid (Neu5Ac) instead of NAM to sustain its growth. Thus, the sialic acid utilization system of the bacterium plays a critical role in the growth and survival of the organism in the absence of NAM. We sought the function of a T. forsythia gene annotated as nanT coding for an inner-membrane sugar transporter located on a sialic acid utilization genetic cluster. To determine the function of this putative sialic acid transporter, an isogenic nanT-deletion mutant generated by allelic replacement strategy was evaluated for biofilm formation on NAM or Neu5Ac, and survival on KB epithelial cells. Moreover, since T. forsythia forms synergistic biofilms with Fusobacterium nucleatum, co-biofilm formation activity in mixed culture and sialic acid uptake in culture were also assessed. The data showed that the nanT-inactivated mutant of T. forsythia was attenuated in its ability to uptake sialic acid. The mutant formed weaker biofilms compared to the wild-type strain in the presence of sialic acid and as co-biofilms with F. nucleatum. Moreover, compared to the wild-type T. forsythia nanT-inactivated mutant showed reduced survival when incubated on KB epithelial cells. Taken together, the data presented here demonstrate that NanT-mediated sialic transportation is essential for sialic acid utilization during biofilm growth and survival of the organism on epithelial cells and implies sialic acid might be key for its survival both in subgingival biofilms and during infection of human epithelial cells in vivo.

  13. Association between salivary sialic acid and periodontal health status among smokers

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    Jwan Ibrahim Jawzali

    2016-07-01

    Conclusion: Salivary free sialic acid may be used as a diagnostic oxidative stress biomarker for periodontal diseases among young current smokers. Cumulative destructive effect of long duration of smoking on the periodontum can be controlled by smoking cessation, good oral hygiene and diet habit in early old ages.

  14. Histochemical localization of sialic acids and antimicrobial substances in eccrine glands of porcine snout skin

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    K. Fukui

    2012-02-01

    Full Text Available The distribution of sialic acids and antimicrobial products (lysozyme, IgA, lactoferrin, β-defensin 2 as well as Rab3D in the eccrine glands of porcine snout skin was studied by sialoglycoconjugate histochemistry and immunohistochemistry. The secretory epithelium consisted of two types of secretory cells: dark and clear cells. The dark cells exhibited considerable amounts of sialoglycoconjugates, which included O-acetylated sialic acids, whereas sialic acids in the sequence Siaα2-3Gal1-4GlcNAc were confined to some of the dark cells. All antimicrobial substances and Rab3D were demonstrated to be also mainly present in some of the dark cells. Additionally, in the cytological and cytochemical features, the different characteristics were observed among the dark cells. The results obtained are discussed with regard to the functional significance of the eccrine glands. The secretory products elaborated by this gland type may function as protective agents in order to preserve the skin integrity of the snout region, considering that sialic acids and antimicrobial substances are important in general defense mechanisms.

  15. Serum sialic acid in malignant tumors, bacterial infections, and chronic liver diseases.

    Science.gov (United States)

    Stefenelli, N; Klotz, H; Engel, A; Bauer, P

    1985-01-01

    The total serum sialic acid concentration was determined in 2,264 persons with various malignant tumors, bacterial infections, rheumatic diseases, and chronic liver diseases, and in a control group. The thiobarbiturate method according to Warren was used. The upper limit (95% percentile) in the control group was 2.23 mumol/ml. Higher values were found in the groups with neoplasms (mean: 3.04 mumol/ml), inflammatory diseases (e.g., pneumonia: 3.02 mumol/ml), and active rheumatoid arthritis (3.05 mumol/ml). In the group with malignant diseases, the sialic acid concentration at the time of diagnosis was highest for bronchial carcinoma (3.29 mumol/ml) and lowest for breast cancer (2.58 mumol/ml). In chronic liver diseases the mean sialic acid level was lower than in a heterogeneous group of noninflammatory and nonneoplastic diseases. The estimation of the serum sialic acid concentration could be useful in the detection of tumor burden and metastases, and in the evaluation of the later course and prognosis of malignant neoplasms if bacterial/inflammatory and active rheumatoid processes can be excluded.

  16. [Variation of the sialic acid-protein ratio in the human cervical mucus (author's transl)].

    Science.gov (United States)

    Kesserü, E; Westphal, N

    1975-01-01

    Serial determinations of total protein and sialic acid concentrations were carried out in individual cervical mucus samples of normal women, throughout the menstrual cycle as well as under the influence of estrogen and progestagen steroids. Total protein was titrated by a modified micro-biuret method and sialic acid was determined using the "Direct Ehrlich" method. Both parameters diminished gradually during the follicular phase of the cycle with lowest values around the time of ovulation, and showed a strong increase during the luteal phase. Administration of ethinylestradiol yielded values significantly lower than those of normal ovulatory phase and under d-Nosgestrel treatment the values were significantly higher than in normal luteal phase. However the proportion of sialic acid as related to total protein showed an inverse behavior, i.e. increased under estrogenic and decreased under progestogenic influence. The cyclic and hormone-induced variations of this ratio were more specific than those of both separate components. Thus, estrogens produce an increase of the sialic acid containing fraction of cervical mucus proteins, while progestagens have an opposite effect. The role of these actions in reproductive physiology is discussed.

  17. C-Reactive Protein, Sialic Acid and Adenosine Deaminase Levels in Serum and Pleural Fluid from Patients with Pleural Effusion

    Science.gov (United States)

    Kim, Ji Woon; Yang, In Ae; Oh, Eun A; Rhyoo, Young Gun; Jang, Young Ho; Ryang, Dong Wook; Yoo, JooYong

    1988-01-01

    Laboratory analysis of pleural fluids is essential to determine underlying diseases. The authors evaluated the clinical significance of C-reactive protein (C-RP), sialic acid (SA), and adenosine deaminase (ADA) determinations in sera and pleural fluids from 37 patients with pleural effusion. (FP12)C-RP and sialic acid levels and ADA activities were higher in exudates than in transudates of pleural fluids. Serum and pleural fluid C-RP levels were high in patients with pyothorax. Determinations of serum sialic acid and the pleural fluid to serum ratio were useful for the differential diagnosis of pulmonary tuberculosis and malignancy. ADA activities of pleural fluid and serum are useful for the differentiation of malignancy from tuberculosis and nonspecific pyothorax. C-RP concentrations of pleural fluid correlated to serum levels. However, concentrations of sialic acid and ADA activities were not correlated to serum levels and only correlated to protein concentrations of pleural fluids. PMID:3154188

  18. Specific synthesis of neurostatin and gangliosides O-acetylated in the outer sialic acids using a sialate transferase.

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    Lorenzo Romero-Ramírez

    Full Text Available Gangliosides are sialic acid containing glycosphingolipids, commonly found on the outer leaflet of the plasma membrane. O-acetylation of sialic acid hydroxyl groups is one of the most common modifications in gangliosides. Studies on the biological activity of O-acetylated gangliosides have been limited by their scarcity in nature. This comparatively small change in ganglioside structure causes major changes in their physiological properties. When the ganglioside GD1b was O-acetylated in the outer sialic acid, it became the potent inhibitor of astroblast and astrocytoma proliferation called Neurostatin. Although various chemical and enzymatic methods to O-acetylate commercial gangliosides have been described, O-acetylation was nonspecific and produced many side-products that reduced the yield. An enzyme with O-acetyltransferase activity (SOAT has been previously cloned from the bacteria Campylobacter jejuni. This enzyme catalyzed the acetylation of oligosaccharide-bound sialic acid, with high specificity for terminal alpha-2,8-linked residues. Using this enzyme and commercial gangliosides as starting material, we have specifically O-acetylated the gangliosides' outer sialic acids, to produce the corresponding gangliosides specifically O-acetylated in the sialic acid bound in alpha-2,3 and alpha-2,8 residues. We demonstrate here that O-acetylation occurred specifically in the C-9 position of the sialic acid. In summary, we present a new method of specific O-acetylation of ganglioside sialic acids that permits the large scale preparation of these modified glycosphingolipids, facilitating both, the study of their mechanism of antitumoral action and their use as therapeutic drugs for treating glioblastoma multiform (GBM patients.

  19. Clinical significance of sialic acid in acute rheumatic fever with and without carditis

    OpenAIRE

    Maher H. Gomaa; Halah Salah Al-Din Hamza; Mamdouh M. Ali; Ahmed Abd-Allah Ali; Osama Abd Al-Motaal Mansour; Ahmed M. Ibrahim

    2012-01-01

    Objective: In Egypt, acute rheumatic fever (ARF) is the most common cause of acquired heart disease. ARF is a clinical syndrome without a specific diagnostic test or single pathognomonic feature, so the aim of this study is to investigate the utility of using serum total sialic acid (TSA) in differentiation between children suffering from ARF with and without carditis. Methods: In the present study, 62 children were divided into three groups: first group, 16 healthy children; second group, 20...

  20. Discrimination between Sialic Acid-Containing Receptors and Pseudoreceptors Regulates Polyomavirus Spread in the Mouse

    OpenAIRE

    1999-01-01

    Variations in the polyomavirus major capsid protein VP1 underlie important biological differences between highly pathogenic large-plaque and relatively nonpathogenic small-plaque strains. These polymorphisms constitute major determinants of virus spread in mice and also dictate previously recognized strain differences in sialyloligosaccharide binding. X-ray crystallographic studies have shown that these determinants affect binding to the sialic acids. Here we report results of further experim...

  1. Glycomic Analysis of Sialic Acid Linkages in Glycans Derived from Blood Serum Glycoproteins

    OpenAIRE

    Alley, William R.; Novotny, Milos V

    2010-01-01

    A number of alterations to the normal glycomic profile have been previously described for a number of diseases and disorders, thus underscoring the medical importance of studying the glycans associated with proteins present in biological samples. An important alteration in cancer progression is an increased level of α2,6-sialylation, which aids in increasing the metastatic potential of tumor cells. Here we report a glycomic method that selectively amidates α2,6-linked sialic acids, while thos...

  2. Sialic acid is required for neuronal inhibition by soluble MAG but not for membrane bound MAG

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    Najat eAl-Bashir

    2016-04-01

    Full Text Available Myelin-Associated Glycoprotein (MAG, a major inhibitor of axonal growth, is a member of the immunoglobulin (Ig super-family. Importantly, MAG (also known as Siglec-4 is a member of the Siglec family of proteins (sialic acid-binding, immunoglobulin-like lectins, MAG binds to complex gangliosides, specifically GD1a and/or GT1b. Therefore, it has been proposed as neuronal receptors for MAG inhibitory effect of axonal growth. Previously, we showed that MAG binds sialic acid through domain 1 at Arg118 and is able to inhibit axonal growth through domain 5.We developed a neurite outgrowth assay (NOG, in which both wild type MAG and mutated MAG (MAG Arg118 are expressed on cells. In addition we also developed a soluble form NOG in which we utilized soluble MAG-Fc and mutated MAG (Arg118-Fc. Only MAG-Fc is able to inhibit neurite outgrowth, but not mutated MAG (Arg118-Fc that has been mutated at its sialic acid binding site. However, both forms of membrane bound MAG- and MAG (Arg118- expressing cells still inhibit neurite outgrowth. Here, we review various results from different groups regarding MAG’s inhibition of axonal growth. Also, we propose a model in which the sialic acid binding is not necessary for the inhibition induced by the membrane form of MAG, but it is necessary for the soluble form of MAG. This finding highlights the importance of understanding the different mechanisms by which MAG inhibits neurite outgrowth in both the soluble fragmented form and the membrane-bound form in myelin debris following CNS damage

  3. Sulfate- and sialic acid-containing glycolipids inhibit DNA polymerase alpha activity.

    Science.gov (United States)

    Simbulan, C M; Taki, T; Tamiya-Koizumi, K; Suzuki, M; Savoysky, E; Shoji, M; Yoshida, S

    1994-03-16

    The effects of various glycolipids on the activity of immunoaffinity-purified calf thymus DNA polymerase alpha were studied in vitro. Preincubation with sialic acid-containing glycolipids, such as sialosylparagloboside (SPG), GM3, GM1, and GD1a, and sulfatide (cerebroside sulfate ester, CSE) dose-dependently inhibited the activity of DNA polymerase alpha, while other glycolipids, as well as free sphingosine and ceramide did not. About 50% inhibition was achieved by preincubating the enzyme with 2.5 microM of CSE, 50 microM of SPG or GM3, and 80 microM of GM1. Inhibition was noncompetitive with both the DNA template and the substrate dTTP, as well as with the other dNTPs. Since the inhibition was largely reversed by the addition of 0.05% Nonidet P40, these glycolipids may interact with the hydrophobic region of the enzyme protein. Apparently, the sulfate moiety in CSE and the sialic acid moiety in gangliosides were essential for the inhibition since neither neutral glycolipids (i.e., glucosylceramide, galactosylceramide, lactosylceramide) nor asialo-gangliosides (GA1 and GA2) showed any inhibitory effect. Furthermore, the ceramide backbone was also found to be necessary for maximal inhibition since the inhibition was largely abolished by substituting the lipid backbone with cholesterol. Increasing the number of sialic acid moieties per molecule further enhanced the inhibition, while elongating the sugar chain diminished it. It was clearly shown that the N-acetyl residue of the sialic acid moiety is particularly essential for inhibition by both SPG and GM3 because the loss of this residue or substitution with a glycolyl residue completely negated their inhibitory effect on DNA polymerase alpha activity.

  4. Sialic acid content in human saliva and anti-influenza activity against human and avian influenza viruses.

    Science.gov (United States)

    Limsuwat, Nattavatchara; Suptawiwat, Ornpreya; Boonarkart, Chompunuch; Puthavathana, Pilaipan; Wiriyarat, Witthawat; Auewarakul, Prasert

    2016-03-01

    It was shown previously that human saliva has higher antiviral activity against human influenza viruses than against H5N1 highly pathogenic avian influenza viruses, and that the major anti-influenza activity was associated with sialic-acid-containing molecules. To further characterize the differential susceptibility to saliva among influenza viruses, seasonal influenza A and B virus, pandemic H1N1 virus, and 15 subtypes of avian influenza virus were tested for their susceptibility to human and chicken saliva. Human saliva showed higher hemagglutination inhibition (HI) and neutralization (NT) titers against seasonal influenza A virus and the pandemic H1N1 viruses than against influenza B virus and most avian influenza viruses, except for H9N2 and H12N9 avian influenza viruses, which showed high HI and NT titers. To understand the nature of sialic-acid-containing anti-influenza factors in human saliva, α2,3- and α2,6-linked sialic acid was measured in human saliva samples using a lectin binding and dot blot assay. α2,6-linked sialic acid was found to be more abundant than α2,3-linked sialic acid, and a seasonal H1N1 influenza virus bound more efficiently to human saliva than an H5N1 virus in a dot blot analysis. These data indicated that human saliva contains the sialic acid type corresponding to the binding preference of seasonal influenza viruses.

  5. Crystallization and preliminary X-ray diffraction analysis of the sialic acid-binding domain (VP8*) of porcine rotavirus strain CRW-8

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Stacy A. [Institute for Glycomics, Griffith University (Gold Coast Campus) PMB 50, Gold Coast Mail Centre, Queensland 9726 (Australia); Holloway, Gavan; Coulson, Barbara S. [Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010 (Australia); Szyczew, Alex J.; Kiefel, Milton J.; Itzstein, Mark von; Blanchard, Helen, E-mail: h.blanchard@griffith.edu.au [Institute for Glycomics, Griffith University (Gold Coast Campus) PMB 50, Gold Coast Mail Centre, Queensland 9726 (Australia)

    2005-06-01

    The sialic acid-binding domain (VP8*) component of the porcine CRW-8 rotavirus spike protein has been overexpressed in E. coli, purified and co-crystallized with an N-acetylneuraminic acid derivative. X-ray diffraction data have been collected to 2.3 Å, which has enabled determination of the structure by molecular replacement. Rotavirus recognition and attachment to host cells involves interaction with the spike protein VP4 that projects outwards from the surface of the virus particle. An integral component of these spikes is the VP8* domain, which is implicated in the direct recognition and binding of sialic acid-containing cell-surface carbohydrates and facilitates subsequent invasion by the virus. The expression, purification, crystallization and preliminary X-ray diffraction analysis of VP8* from porcine CRW-8 rotavirus is reported. Diffraction data have been collected to 2.3 Å resolution, enabling the determination of the VP8* structure by molecular replacement.

  6. Uptake of sialic acid by human erythrocyte. Characterization of a transport system.

    Science.gov (United States)

    Bulai, Tatiana; Bratosin, Daniela; Artenie, Vlad; Montreuil, Jean

    2003-01-01

    Upon incubation of human red blood cells (RBC) with [4-9-14C] N-acetylneuraminic acid, the cells incorporated this sugar, as demonstrated by the identification of labelled N-acetylmannosamine in the cytosol, as a result of the action of the sialic acid pyruvate-lyase we discovered previously (Biochimie 84 (2002) 655). The mechanism is saturable and indicates the presence of a limited number of transporter molecules in the RBC membrane. This transport process may have relevance to the desialylation of membrane glycoconjugates which occurs during ageing of erythrocytes.

  7. Harnessing cancer cell metabolism for theranostic applications using metabolic glycoengineering of sialic acid in breast cancer as a pioneering example.

    Science.gov (United States)

    Badr, Haitham A; AlSadek, Dina M M; El-Houseini, Motawa E; Saeui, Christopher T; Mathew, Mohit P; Yarema, Kevin J; Ahmed, Hafiz

    2017-02-01

    Abnormal cell surface display of sialic acids - a family of unusual 9-carbon sugars - is widely recognized as distinguishing feature of many types of cancer. Sialoglycans, however, typically cannot be identified with sufficiently high reproducibility and sensitivity to serve as clinically accepted biomarkers and similarly, almost all efforts to exploit cancer-specific differences in sialylation signatures for therapy remain in early stage development. In this report we provide an overview of important facets of glycosylation that contribute to cancer in general with a focus on breast cancer as an example of malignant disease characterized by aberrant sialylation. We then describe how cancer cells experience nutrient deprivation during oncogenesis and discuss how the resulting metabolic reprogramming, which endows breast cancer cells with the ability to obtain nutrients during scarcity, constitutes an "Achilles' heel" that we believe can be exploited by metabolic glycoengineering (MGE) strategies to develop new diagnostic methods and therapeutic approaches. In particular, we hypothesize that adaptations made by breast cancer cells that allow them to efficiently scavenge sialic acid during times of nutrient deprivation renders them vulnerable to MGE, which refers to the use of exogenously-supplied, non-natural monosaccharide analogues to modulate targeted aspects of glycosylation in living cells and animals. In specific, once non-natural sialosides are incorporated into the cancer "sialome" they can be exploited as epitopes for immunotherapy or as chemical tags for targeted delivery of imaging or therapeutic agents selectively to tumors.

  8. Human adenovirus 52 uses sialic acid-containing glycoproteins and the coxsackie and adenovirus receptor for binding to target cells.

    Directory of Open Access Journals (Sweden)

    Annasara Lenman

    2015-02-01

    Full Text Available Most adenoviruses attach to host cells by means of the protruding fiber protein that binds to host cells via the coxsackievirus and adenovirus receptor (CAR protein. Human adenovirus type 52 (HAdV-52 is one of only three gastroenteritis-causing HAdVs that are equipped with two different fiber proteins, one long and one short. Here we show, by means of virion-cell binding and infection experiments, that HAdV-52 can also attach to host cells via CAR, but most of the binding depends on sialylated glycoproteins. Glycan microarray, flow cytometry, surface plasmon resonance and ELISA analyses reveal that the terminal knob domain of the long fiber (52LFK binds to CAR, and the knob domain of the short fiber (52SFK binds to sialylated glycoproteins. X-ray crystallographic analysis of 52SFK in complex with 2-O-methylated sialic acid combined with functional studies of knob mutants revealed a new sialic acid binding site compared to other, known adenovirus:glycan interactions. Our findings shed light on adenovirus biology and may help to improve targeting of adenovirus-based vectors for gene therapy.

  9. Salmonella O48 Serum Resistance is Connected with the Elongation of the Lipopolysaccharide O-Antigen Containing Sialic Acid

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    Aleksandra Pawlak

    2017-09-01

    Full Text Available Complement is one of the most important parts of the innate immune system. Some bacteria can gain resistance against the bactericidal action of complement by decorating their outer cell surface with lipopolysaccharides (LPSs containing a very long O-antigen or with specific outer membrane proteins. Additionally, the presence of sialic acid in the LPS molecules can provide a level of protection for bacteria, likening them to human cells, a phenomenon known as molecular mimicry. Salmonella O48, which contains sialic acid in the O-antigen, is the major cause of reptile-associated salmonellosis, a worldwide public health problem. In this study, we tested the effect of prolonged exposure to human serum on strains from Salmonella serogroup O48, specifically on the O-antigen length. After multiple passages in serum, three out of four tested strains became resistant to serum action. The gas-liquid chromatography/tandem mass spectrometry analysis showed that, for most of the strains, the average length of the LPS O-antigen increased. Thus, we have discovered a link between the resistance of bacterial cells to serum and the elongation of the LPS O-antigen.

  10. Characterization of influenza virus sialic acid receptors in minor poultry species.

    Science.gov (United States)

    Kimble, Brian; Nieto, Gloria Ramirez; Perez, Daniel R

    2010-12-09

    It is commonly accepted that avian influenza viruses (AIVs) bind to terminal α2,3 sialic acid (SA) residues whereas human influenza viruses bind to α2,6 SA residues. By a series of amino acid changes on the HA surface protein, AIVs can switch receptor specificity and recognize α2,6 SA positive cells, including human respiratory epithelial cells. Animal species, like pigs and Japanese quail, that contain both α2,3 and α2,6 SA become ideal environments for receptor switching. Here, we describe the SA patterns and distributions in 6 common minor domestic poultry species: Peking duck, Toulouse geese, Chinese ring-neck pheasant, white midget turkey, bobwhite quail, and pearl guinea fowl. Lectins specific to α2,3 and α2,6 SA (Maakia amurensis agglutinin and Sambuca nigra agglutinin, respectively) were used to detect SA by an alkaline phosphotase-based method and a fluorescent-based method. Differences in SA moieties and their ability to bind influenza viruses were visualized by fluorescent labeling of 4 different H3N2 influenza viruses known to be specific for one receptor or the other. The geese and ducks showed α2,3 SA throughout the respiratory tract and marginal α2,6 SA only in the colon. The four other avian species showed both α2,3 and α2,6 SA in the respiratory tract and the intestines. Furthermore, the turkey respiratory tract showed a positive correlation between age and α2,6 SA levels. The fact that these birds have both avian and human flu receptors, combined with their common presence in backyard farms and live bird markets worldwide, mark them as potential mixing bowl species and necessitates improved surveillance and additional research about the role of these birds in influenza host switching.

  11. Characterization of influenza virus sialic acid receptors in minor poultry species

    Directory of Open Access Journals (Sweden)

    Nieto Gloria

    2010-12-01

    Full Text Available Abstract It is commonly accepted that avian influenza viruses (AIVs bind to terminal α2,3 sialic acid (SA residues whereas human influenza viruses bind to α2,6 SA residues. By a series of amino acid changes on the HA surface protein, AIVs can switch receptor specificity and recognize α2,6 SA positive cells, including human respiratory epithelial cells. Animal species, like pigs and Japanese quail, that contain both α2,3 and α2,6 SA become ideal environments for receptor switching. Here, we describe the SA patterns and distributions in 6 common minor domestic poultry species: Peking duck, Toulouse geese, Chinese ring-neck pheasant, white midget turkey, bobwhite quail, and pearl guinea fowl. Lectins specific to α2,3 and α2,6 SA (Maakia amurensis agglutinin and Sambuca nigra agglutinin, respectively were used to detect SA by an alkaline phosphotase-based method and a fluorescent-based method. Differences in SA moieties and their ability to bind influenza viruses were visualized by fluorescent labeling of 4 different H3N2 influenza viruses known to be specific for one receptor or the other. The geese and ducks showed α2,3 SA throughout the respiratory tract and marginal α2,6 SA only in the colon. The four other avian species showed both α2,3 and α2,6 SA in the respiratory tract and the intestines. Furthermore, the turkey respiratory tract showed a positive correlation between age and α2,6 SA levels. The fact that these birds have both avian and human flu receptors, combined with their common presence in backyard farms and live bird markets worldwide, mark them as potential mixing bowl species and necessitates improved surveillance and additional research about the role of these birds in influenza host switching.

  12. The crystal structure of Helicobacter pylori HP1029 highlights the functional diversity of the sialic acid-related DUF386 family.

    Science.gov (United States)

    Vallese, Francesca; Percudani, Riccardo; Fischer, Wolfgang; Zanotti, Giuseppe

    2015-09-01

    The proteins of the YhcH/YjgK/YiaL (DUF386) family have been implicated in the bacterial metabolism of host-derived sialic acids and biofilm formation, although their precise biochemical function remains enigmatic. We present here the crystal structure of protein HP1029 from Helicobacter pylori. The protein is a homodimer, in which each monomer comprises a molecular core formed by 12 antiparallel β-strands arranged in two β-sheets flanked by helices. The sandwich formed by the sheets assumes the shape of a funnel opened at one end, with a zinc ion present at the bottom of the funnel. The crystal structure unequivocally shows that HP1029 belongs to the DUF386 family. Although no bioinformatics evidence has been found for sialic acid catabolism in H. pylori, the genomic context of HP1029 in Helicobacter and related organisms suggests a possible role in the metabolism of bacterial surface saccharides, such as pseudaminic acid and its derivatives.

  13. Lectin-histochemical reactivity of sialic acid in breast cancer and its relationship to prognosis using limulus polyphemus agglutinin.

    Science.gov (United States)

    Ding, K; Yamaguchi, A; Goi, T; Maehara, M; Nakagawara, G

    1997-04-01

    Studies of circulating sialic acid have revealed its relationship with a variety of malignant tumors. It is not vet clear whether sialic acid could be used as a prognostic marker of breast cancer, and few studies have examined sialic acid expression in the cell membrane and cytoplasm of breast cancer cells by means of the lectin-histochemical technique. In the present study, we used biotinylated limulus polyphemus agglutinin (LPA), a special binding lectin of sialic acid, to stain sialic acid in breast cancer cells. Of the 104 cases of breast cancer examined, 59 (56.7%) positive cases were observed. There was a significant correlation between the LPA staining and the clinicopathologic features of all patients, including pathological stage and lymph node metastasis. Among the 100 patients who underwent curative operation, the mean disease-free survival rate of the 45 patients who were LPA-negative was significantly higher than that of the 55 LPA-positive patients (psialic acid in breast cancer could be used as a marker of malignancy potential, as well as a poor survival factor, and the biotinylated LPA assay may provide a convenient and useful method to predict the prognosis of breast cancer.

  14. APOPTOSIS OF EPIDIDYMIS EPITHELIUM AND CONTENT OF EPIDIDYMIS SIALIC ACID FOLLOWING TORSED/DETORSED TESTES IN RAT

    Institute of Scientific and Technical Information of China (English)

    赵豫刚; 郑新民; 杨志伟; 李世文; 胡礼泉

    2004-01-01

    Objective To investigate the apoptosis of epididymis epithelium and the change of epididymis sialic acid following torsed/detorsed testes. Methods Twenty four adult male Sprague-Dawley rats were subjected to unilateral 720 testicular torsion with the duration of 2h and 4h, then repaired. The ischemic epididymis were collected for detecting the content of sialic acid by using spectrophotometry and the apoptosis with TUNEL technique.Results There were no statistically significant difference in the apoptosis of epididymis epithelium [ ( 9. 51 +2.78)% vs (6. 34 +1.98)% ] and the content of epididymis sialic acid(23. 3851 +9. 2199mg/mgprot vs 19. 36616. 3373mg/mgprot ) at 24h between following 2h-torsed/detorsed testes and those of sham group. There were statistically significant difference in the apopotosis of epididymis epithelium [ (46. 81 + 3. 55 )% vs (6. 34 ± 1.98 )% ] and the content of epididymis sialic acid ( 13. 7249 + 7. 8006mg/ mgprot vs 19. 3661 + 6. 3 373 mg/ mgprot ) at 24h between following 4h-torsed/detorsed testes and those of sham group ( P < O. 05 ). Conclusion The results suggest that the sialic acid-secreting-function of epididymis remain normal at 24h following 2h-torsed/detorsed testes, while the apoptosis index of epididymis epithelium do not increase. The epididymis would be injured at 24h following 4htorsed/detorsed testes, while the apoptosis index increased.

  15. Multifunctional phenylboronic acid-tagged fluorescent silica nanoparticles via thiol-ene click reaction for imaging sialic acid expressed on living cells.

    Science.gov (United States)

    Cheng, Liwei; Zhang, Xianxia; Zhang, Zhengyong; Chen, Hui; Zhang, Song; Kong, Jilie

    2013-10-15

    Multifunctional fluorescent silica nanoparticles with phenylboronic acid tags were developed for labeling sialic acid on the surface of living cancer cells. In this paper, fluorescent silica nanoparticles (FSNPs) with strong and stable emission at 515 nm were firstly prepared through a reverse microemulsion process, and then modified with highly selective phenylboronic acid (PBA) tags on their surface via an aqueous 'thiol-ene' click reaction. These nanoparticles had a hydrodynamic diameter of 92.6 ± 9.1 nm, and a bright fluorescence signal, which is 366 times higher than that of a single dye molecule. Meanwhile, these PBA-tagged FSNPs were found very stable in aqueous solution as well as in cell culture medium, verified by transmission electron microscopy, X-ray photoelectron spectroscopy and zeta potential analysis. The over-expressed sialic acid (SA) on the membrane of living HeLa cells was visualized in situ by a confocal laser scanning microscopy, ascribed to the specific interaction between PBA and SA. Thus, the PBA-FSBPs showed a great potential in probing SA expressed on living cells with high selectivity and sensitivity. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Differential expression of the α2,3-sialic acid residues in breast cancer is associated with metastatic potential.

    Science.gov (United States)

    Cui, Hongxia; Lin, Yu; Yue, Liling; Zhao, Xuemei; Liu, Jicheng

    2011-05-01

    Aberrant sialylation is closely associated with the malignant phenotype of cancer cells and metastatic potential. However, the precise nature of the molecules in breast cancers has not been unveiled. In this study, we investigated the expression levels of α2,3-sialic acid residues of 50 primary tumor cases, 50 pair-matched lymph node metastasis tumor samples and in the MDA-MB-231, T-47D and MCF-7 breast cancer cell lines with different metastatic potential. The expression of α2,3-sialic acid residues was analyzed by histochemistry, cytochemistry and flow cytometry with Maackia amurensis lectin (MAL). The invasion and migration abilities of cells were examined using cell adhesion and transwell in vitro assays. Pair-matched lymph node metastasis tumor samples exhibited higher levels of expression of α2,3-sialic acid residues compared to that of primary tumors (P=0.0432). Furthermore, of 38 tumors cases in T1/T2 stages, 31 (81.58%) had weak staining for MAL, which specifically binds to α2,3-sialic acid residues, whereas of 12 tumor cases in T3/T4 stages, only 1 (8.33%) had weak reactions for MAL. The highly metastatic breast cancer cell line MDA-MB-231 exhibited the strongest binding to MAL and the highest expression levels of α2,3-sialic acid residues among the selected cell lines, depending on mRNA expression levels of α2,3-sialyltransferase gene. The adhesion, invasion and migration activities confirmed that MDA-MB-231 exhibited the greater cell adhesion to, migration toward and invasion to Matrigel. Taken together, the high expression of α2,3-sialic acid residues in breast cancer was associated with metastatic potential. This property may be important for developing new therapeutic approaches for breast cancer.

  17. Changes in ganglioside contents, plasma sialic acid and cAMP levels in experimental hepatoma in mice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Abstract The present sutdy was designed to assess whether changes in glycolipids and cyclic AMP contents might serve as markers for the diagnosis of malignancy in the liver. The experimental model was a transplantable murine hepatoma. Experimental mice were divided into three groups:(1) a therapeutic group. which had been transplanted with hepatoma and treated with the antimetabolism drug 5-flurouracil(0.2mg/day i.p).(2) a control group, which had been transplanted with hepatoma and treated with 0.2ml 0.9% NaCl day and (3) a normal group of mice . The ganglioside and cAMP contents in the hepatoma tissue, plasma cAMP, total and lipid-bound sialic acid levels and red blood cell memebrane sialic acid levels were determined. Results showed that the ganglioside content, total and lipid-bound sialic acid levels in the control group were significantly higher than those in the livers of normal mice(P<0.01) while these respective values in the therapeutic group were significantly lower than those in the control group(P<0.01).The cAMP levels of tumor tissues and plasma in the control group were lower than those in normal mice. No significant difference in red blood cell membrane sialic acid content was observed between the therapeutic and control groups though levels for both were higher than those in normal mice. These results indicate that ganglioside ocntent and sialic acid levels in hepatoma tissues were significantly elevated, and cAMP levels in hepatoma tissues were significantly decreased during proliferation and abnormal differentiation. Key words transplantable hepatoma, gangliosides , sialic acid, cyclic adenosine mono-phosphate, 5-flurouracil 摘自Molecular and cellular biochemistry, 2000; Vol 207,29~33 该杂志摘要被美国科学引证索引(SCI)收录

  18. Discrimination between sialic acid-containing receptors and pseudoreceptors regulates polyomavirus spread in the mouse.

    Science.gov (United States)

    Bauer, P H; Cui, C; Liu, W R; Stehle, T; Harrison, S C; DeCaprio, J A; Benjamin, T L

    1999-07-01

    Variations in the polyomavirus major capsid protein VP1 underlie important biological differences between highly pathogenic large-plaque and relatively nonpathogenic small-plaque strains. These polymorphisms constitute major determinants of virus spread in mice and also dictate previously recognized strain differences in sialyloligosaccharide binding. X-ray crystallographic studies have shown that these determinants affect binding to the sialic acids. Here we report results of further experiments designed to test the importance of specific contacts between VP1 and the carbohydrate moieties of the receptor. With minor exceptions, substitutions at positions predicted from crystallography to be important in binding the terminal alpha-2,3-linked sialic acid or the penultimate sugar (galactose) destroyed the ability of the virus to replicate in cell culture. Substitutions that prevented binding to a branched disialyloligosaccharide were found to result in viruses that were both viable in culture and tumorigenic in the mouse. Conversely, substitutions that allowed recognition and binding of the branched carbohydrate chain inhibited spread in the mouse, though the viruses remained viable in culture. Mice of five different inbred strains, all highly susceptible to large-plaque virus, showed resistance to the spread of polyomavirus strains bearing the VP1 type which binds the branched-chain receptor. We suggest that glycoproteins bearing the appropriate O-linked branched sialyloligosaccharide chains are effective pseudoreceptors in the host and that they block the spread of potentially tumorigenic or virulent virus strains.

  19. Requirement for sialic acid on the endothelial ligand of a lymphocyte homing receptor.

    Science.gov (United States)

    True, D D; Singer, M S; Lasky, L A; Rosen, S D

    1990-12-01

    The entry of blood-borne lymphocytes into most secondary lymphoid organs is initiated by a highly specific adhesive interaction with the specialized cuboidal endothelial cells of high endothelial venules (HEV). The adhesive receptors on lymphocytes that dictate interactions with HEV in different lymphoid organs are called homing receptors, signifying their critical role in controlling organ-selective lymphocyte migration. Considerable work has established that the mouse peripheral lymph node homing receptor (pnHR), defined by the mAb MEL-14, functions as a lectin-like adhesive protein. We have previously shown that sialidase treatment of peripheral lymph node (PN) HEV abrogates lymphocyte attachment to the HEV both in vivo and in vitro. We extend this evidence by demonstrating that Limax agglutinin (LA), a sialic acid-specific lectin, when reacted with HEV exposed in cryostat-cut tissue sections, blocks lymphocyte attachment to PN HEV and, unexpectedly, to the HEV of Peyer's patches (PP) as well. Using a recombinant form of the pnHR as a histochemical probe for its cognate adhesive site (HEV-ligand) on PN HEV, we demonstrate that both sialidase and Limax agglutinin functionally inactive this ligand. It is concluded that the requirement for sialic acid is at the level of the pnHR interaction with its HEV ligand. A distinct sialyloligosaccharide may encode the recognition determinant of a PP HEV ligand.

  20. Evaluation of serum sialic acid, heat stable alkaline phosphatase and fucose as markers of breast carcinoma.

    Science.gov (United States)

    Patel, P S; Baxi, B R; Adhvaryu, S G; Balar, D B

    1990-01-01

    Serum levels of total sialic acid (TSA), lipid bound sialic acid (LSA), heat stable alkaline phosphatase (HSAP) and fucose were measured in 39 patients with breast carcinoma, 14 patients with benign breast diseases and 35 healthy female individuals. Elevated levels of the four biomarkers in breast carcinoma were significant when compared with controls (p less than 0.001). Fucose levels were most sensitive (71.8%), while TSA levels were most specific (64.3%) for breast carcinoma. Sensitivity and specificity were 100% when combinations of LSA with fucose and TSA with HSAP were studied respectively. LSA was significantly elevated in infiltrating duct carcinoma patients compared with lobular carcinoma (p less than 0.001). TSA, HSAP and fucose also had lower mean values in lobular carcinoma as compared to infiltrating duct carcinoma. Increase in the levels of LSA and HSAP after surgical removal of the tumor in breast carcinoma occurred prior to the clinical evidence of the recurrence. The results indicate that the combination of the markers studied might be useful in breast cancer diagnosis and treatment monitoring.

  1. Glycomic analysis of sialic acid linkages in glycans derived from blood serum glycoproteins.

    Science.gov (United States)

    Alley, William R; Novotny, Milos V

    2010-06-04

    A number of alterations to the normal glycomic profile have been previously described for a number of diseases and disorders, thus underscoring the medical importance of studying the glycans associated with proteins present in biological samples. An important alteration in cancer progression is an increased level of alpha2,6-sialylation, which aids in increasing the metastatic potential of tumor cells. Here we report a glycomic method that selectively amidates alpha2,6-linked sialic acids, while those that are alpha2,3-linked undergo spontaneous lactonization. Following subsequent permethylation, MALDI-TOF MS analysis revealed that many sialylated glycans present on glycoproteins found in blood serum featured increased levels of alpha2,6-sialylation in breast cancer samples. On the basis of the altered ratios of alpha2,3-linked to alpha2,6-linked sialic acids, many of these glycans became diagnostically relevant when they did not act as such indicators when based on traditional glycomic profiling alone.

  2. Axillary versus peripheral blood levels of sialic acid, ferritin, and CEA in patients with breast cancer.

    Science.gov (United States)

    Monti, M; Catania, S; Locatelli, E; Gandini, R; Reggiani, A; Cunietti, E

    1990-12-01

    Serum levels of total sialic acid, carcinoembryonic antigen (CEA), ferritin, lactate dehydrogenase, and creatine phosphokinase were measured both in tumor drainage blood (axillary vein) and in peripheral blood obtained from 121 breast cancer patients during surgery. No significant differences between mean values in peripheral and tumor draining blood, between cancer patients and healthy controls, or between patients with or without axillary lymph node metastases were found for any of the markers. Both ferritin and CEA levels were higher in axillary and peripheral blood from patients with central breast cancer versus other sites but the difference was significant only for CEA (p less than 0.05). CEA levels were significantly higher (p less than 0.01) in patients with greater than 2 cm diameter carcinomas versus T1 stage patients in axillary but not in peripheral blood. When the cephalic vein was clamped before the axillary sample was taken, ferritin showed a significant increase (p less than 0.05). We conclude that measurement of sialic acid, CEA, and ferritin in axillary venous blood in breast cancer patients is not of clinical benefit, although further data are needed to clarify whether other advantages can be derived.

  3. Complementing the sugar code: role of GAGs and sialic acid in complement regulation

    Directory of Open Access Journals (Sweden)

    Alex eLangford-Smith

    2015-02-01

    Full Text Available Sugar molecules play a vital role on both microbial and mammalian cells, where they are involved in cellular communication, govern microbial virulence and modulate host immunity and inflammatory responses. The complement cascade, as part of a host’s innate immune system, is a potent weapon against invading bacteria but has to be tightly regulated to prevent inappropriate attack and damage to host tissues. A number of complement regulators, such as factor H and properdin, interact with sugar molecules, such as glycosaminoglycans and sialic acid, on host and pathogen membranes and direct the appropriate complement response by either promoting the binding of complement activators or inhibitors. The binding of these complement regulators to sugar molecules can vary from location to location, due to their different specificities and because distinct structural and functional subpopulations of sugars are found in different human organs, such as the brain, kidney and eye. This review will cover recent studies that have provided important new insights into the role of glycosaminoglycans and sialic acid in complement regulation and how sugar recognition may be compromised in disease

  4. Infection with human H1N1 influenza virus affects the expression of sialic acids of metaplastic mucous cells in the ferret airways

    DEFF Research Database (Denmark)

    Kirkeby, Svend; Martel, Cyril Jean-Marie; Aasted, Bent

    2009-01-01

    Glycans terminating in sialic acids serve as receptors for influenza viruses. In this study ferrets were infected with influenza virus A/New Caledonia/20/99, and the in situ localization of sialic acids linked a2-3 and a2-6 in the airways was investigated in infected and non-infected animals by use...

  5. Comparison of backbone dynamics of the type III antifreeze protein and antifreeze-like domain of human sialic acid synthase

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong-Geun [Gyeongsang National University, Department of Chemistry and Research Institute of Natural Science (Korea, Republic of); Park, Chin-Ju [Gwangju Institute of Science and Technology, Division of Liberal Arts and Sciences and Department of Chemistry (Korea, Republic of); Kim, Hee-Eun; Seo, Yeo-Jin; Lee, Ae-Ree; Choi, Seo-Ree; Lee, Shim Sung; Lee, Joon-Hwa, E-mail: joonhwa@gnu.ac.kr [Gyeongsang National University, Department of Chemistry and Research Institute of Natural Science (Korea, Republic of)

    2015-02-15

    Antifreeze proteins (AFPs) are found in a variety of cold-adapted (psychrophilic) organisms to promote survival at subzero temperatures by binding to ice crystals and decreasing the freezing temperature of body fluids. The type III AFPs are small globular proteins that consist of one α-helix, three 3{sub 10}-helices, and two β-strands. Sialic acids play important roles in a variety of biological functions, such as development, recognition, and cell adhesion and are synthesized by conserved enzymatic pathways that include sialic acid synthase (SAS). SAS consists of an N-terminal catalytic domain and a C-terminal antifreeze-like (AFL) domain, which is similar to the type III AFPs. Despite having very similar structures, AFL and the type III AFPs exhibit very different temperature-dependent stability and activity. In this study, we have performed backbone dynamics analyses of a type III AFP (HPLC12 isoform) and the AFL domain of human SAS (hAFL) at various temperatures. We also characterized the structural/dynamic properties of the ice-binding surfaces by analyzing the temperature gradient of the amide proton chemical shift and its correlation with chemical shift deviation from random coil. The dynamic properties of the two proteins were very different from each other. While HPLC12 was mostly rigid with a few residues exhibiting slow motions, hAFL showed fast internal motions at low temperature. Our results provide insight into the molecular basis of thermostability and structural flexibility in homologous psychrophilic HPLC12 and mesophilic hAFL proteins.

  6. Plant lectin can target receptors containing sialic acid, exemplified by podoplanin, to inhibit transformed cell growth and migration.

    Directory of Open Access Journals (Sweden)

    Jhon Alberto Ochoa-Alvarez

    Full Text Available Cancer is a leading cause of death of men and women worldwide. Tumor cell motility contributes to metastatic invasion that causes the vast majority of cancer deaths. Extracellular receptors modified by α2,3-sialic acids that promote this motility can serve as ideal chemotherapeutic targets. For example, the extracellular domain of the mucin receptor podoplanin (PDPN is highly O-glycosylated with α2,3-sialic acid linked to galactose. PDPN is activated by endogenous ligands to induce tumor cell motility and metastasis. Dietary lectins that target proteins containing α2,3-sialic acid inhibit tumor cell growth. However, anti-cancer lectins that have been examined thus far target receptors that have not been identified. We report here that a lectin from the seeds of Maackia amurensis (MASL with affinity for O-linked carbohydrate chains containing sialic acid targets PDPN to inhibit transformed cell growth and motility at nanomolar concentrations. Interestingly, the biological activity of this lectin survives gastrointestinal proteolysis and enters the cardiovascular system to inhibit melanoma cell growth, migration, and tumorigenesis. These studies demonstrate how lectins may be used to help develop dietary agents that target specific receptors to combat malignant cell growth.

  7. Comparative Analyses of the Lipooligosaccharides from Nontypeable Haemophilus influenzae and Haemophilus haemolyticus Show Differences in Sialic Acid and Phosphorylcholine Modifications.

    Science.gov (United States)

    Post, Deborah M B; Ketterer, Margaret R; Coffin, Jeremy E; Reinders, Lorri M; Munson, Robert S; Bair, Thomas; Murphy, Timothy F; Foster, Eric D; Gibson, Bradford W; Apicella, Michael A

    2016-01-04

    Haemophilus haemolyticus and nontypeable Haemophilus influenzae (NTHi) are closely related upper airway commensal bacteria that are difficult to distinguish phenotypically. NTHi causes upper and lower airway tract infections in individuals with compromised airways, while H. haemolyticus rarely causes such infections. The lipooligosaccharide (LOS) is an outer membrane component of both species and plays a role in NTHi pathogenesis. In this study, comparative analyses of the LOS structures and corresponding biosynthesis genes were performed. Mass spectrometric and immunochemical analyses showed that NTHi LOS contained terminal sialic acid more frequently and to a higher extent than H. haemolyticus LOS did. Genomic analyses of 10 strains demonstrated that H. haemolyticus lacked the sialyltransferase genes lic3A and lic3B (9/10) and siaA (10/10), but all strains contained the sialic acid uptake genes siaP and siaT (10/10). However, isothermal titration calorimetry analyses of SiaP from two H. haemolyticus strains showed a 3.4- to 7.3-fold lower affinity for sialic acid compared to that of NTHi SiaP. Additionally, mass spectrometric and immunochemical analyses showed that the LOS from H. haemolyticus contained phosphorylcholine (ChoP) less frequently than the LOS from NTHi strains. These differences observed in the levels of sialic acid and ChoP incorporation in the LOS structures from H. haemolyticus and NTHi may explain some of the differences in their propensities to cause disease.

  8. Comparative Analyses of the Lipooligosaccharides from Nontypeable Haemophilus influenzae and Haemophilus haemolyticus Show Differences in Sialic Acid and Phosphorylcholine Modifications

    Science.gov (United States)

    Post, Deborah M. B.; Ketterer, Margaret R.; Coffin, Jeremy E.; Reinders, Lorri M.; Munson, Robert S.; Bair, Thomas; Murphy, Timothy F.; Foster, Eric D.; Gibson, Bradford W.

    2016-01-01

    Haemophilus haemolyticus and nontypeable Haemophilus influenzae (NTHi) are closely related upper airway commensal bacteria that are difficult to distinguish phenotypically. NTHi causes upper and lower airway tract infections in individuals with compromised airways, while H. haemolyticus rarely causes such infections. The lipooligosaccharide (LOS) is an outer membrane component of both species and plays a role in NTHi pathogenesis. In this study, comparative analyses of the LOS structures and corresponding biosynthesis genes were performed. Mass spectrometric and immunochemical analyses showed that NTHi LOS contained terminal sialic acid more frequently and to a higher extent than H. haemolyticus LOS did. Genomic analyses of 10 strains demonstrated that H. haemolyticus lacked the sialyltransferase genes lic3A and lic3B (9/10) and siaA (10/10), but all strains contained the sialic acid uptake genes siaP and siaT (10/10). However, isothermal titration calorimetry analyses of SiaP from two H. haemolyticus strains showed a 3.4- to 7.3-fold lower affinity for sialic acid compared to that of NTHi SiaP. Additionally, mass spectrometric and immunochemical analyses showed that the LOS from H. haemolyticus contained phosphorylcholine (ChoP) less frequently than the LOS from NTHi strains. These differences observed in the levels of sialic acid and ChoP incorporation in the LOS structures from H. haemolyticus and NTHi may explain some of the differences in their propensities to cause disease. PMID:26729761

  9. Serum lipid-bound sialic acid as a marker in breast cancer.

    Science.gov (United States)

    Dnistrian, A M; Schwartz, M K; Katopodis, N; Fracchia, A A; Stock, C C

    1982-11-01

    The reliability of lipid-bound sialic acid (LSA) as a marker in breast cancer was evaluated in 78 normal subjects, 106 patients with benign breast disease, 64 patients with primary operable breast cancer, and 61 patients with recurrent metastatic breast cancer. LSA levels were determined before and after mastectomy and during chemotherapy in selected patients to determine the value of LSA in monitoring therapy and predicting response. LSA levels greater than 20 mg/dl were not seen in normal subjects but were present in patients with benign breast disease (13%), primary breast cancer (47%) and recurrent metastatic breast cancer (62%). LSA levels decreased after initiation of chemotherapy and remained low in patients clinically disease-free. Recurrences were associated with elevated LSA in patients failing chemotherapy or endocrine ablative surgery. LSA measurements appeared to be of limited value in the detection of breast cancer but serial measurements may be useful in assessing disease progression and identifying patients resistant to therapy.

  10. Salivary total sialic acid levels increase in breast cancer patients: a preliminary study.

    Science.gov (United States)

    Oztürk, Leyla Koç; Emekli-Alturfan, Ebru; Kaşikci, Emel; Demir, Gokhan; Yarat, Aysen

    2011-09-01

    Breast cancer is the most common cancer in women living in the Western world, even though it occurs worldwide. Cancer and cancer therapy induce multiple oral complications including dental and periodontal disease. Saliva is a complex and dynamic biologic fluid, which reflects both oral and systemic changes. While saliva is easily accessible body fluid, there has been little effort to study its value in cancer diagnosis. Sialic acids (SA), the end moieties of the carbohydrate chains, are biologically important and essential for functions of glycoconjugates that are reported to be altered in both blood and saliva of various cancer patients. Increased sialylation has been shown to be a characteristic feature in cancer tissue and blood in breast cancer patients. However, there is no data about salivary SA in breast cancer. The aim of this study was to evaluate salivary total sialic acid (TSA) levels in breast cancer patients who were under chemotheraphy. The study included 15 breast cancer patients in different stages and 10 healthy individuals as age-matched controls. Unstimulated whole saliva was collected. Salivary total protein and SA levels were determined. Flow rate was calculated from salivary volume by the time of secretion. Salivary SA was significantly higher and total protein was lower in breast cancer patients compared to controls. It is concluded that sialylation may be increased in saliva of patients with breast cancer as the same way for cancer tissue and for blood . Increased salivary SA may therefore be useful as a non-invasive predictive marker for breast cancer patients and for the prevention and management of oral complications of cancer and cancer therapy to improve oral function and quality-of-life. The effects of different types of chemotherapies and different stages of the disease on salivary SA levels and salivary sialo-glycomic are worthy of being further investigated in breast cancer patients.

  11. Sialic Acid on the Glycosylphosphatidylinositol Anchor Regulates PrP-mediated Cell Signaling and Prion Formation.

    Science.gov (United States)

    Bate, Clive; Nolan, William; Williams, Alun

    2016-01-01

    The prion diseases occur following the conversion of the cellular prion protein (PrP(C)) into disease-related isoforms (PrP(Sc)). In this study, the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrP(C) in prion formation was examined using a cell painting technique. PrP(Sc) formation in two prion-infected neuronal cell lines (ScGT1 and ScN2a cells) and in scrapie-infected primary cortical neurons was increased following the introduction of PrP(C). In contrast, PrP(C) containing a GPI anchor from which the sialic acid had been removed (desialylated PrP(C)) was not converted to PrP(Sc). Furthermore, the presence of desialylated PrP(C) inhibited the production of PrP(Sc) within prion-infected cortical neurons and ScGT1 and ScN2a cells. The membrane rafts surrounding desialylated PrP(C) contained greater amounts of sialylated gangliosides and cholesterol than membrane rafts surrounding PrP(C). Desialylated PrP(C) was less sensitive to cholesterol depletion than PrP(C) and was not released from cells by treatment with glimepiride. The presence of desialylated PrP(C) in neurons caused the dissociation of cytoplasmic phospholipase A2 from PrP-containing membrane rafts and reduced the activation of cytoplasmic phospholipase A2. These findings show that the sialic acid moiety of the GPI attached to PrP(C) modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrP(Sc) formation. These results suggest that pharmacological modification of GPI glycosylation might constitute a novel therapeutic approach to prion diseases.

  12. Evaluation of Sialic Acid and Acute Phase Proteins (Haptoglobin and Serum Amyloid A in Clinical and Subclinical Bovine Mastitis

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    S. Nazifi*, M. Haghkhah1, Z. Asadi, M. Ansari-Lari2, M. R. Tabandeh3, Z. Esmailnezhad and M. Aghamiri

    2011-01-01

    Full Text Available The present study was conducted to evaluate the concentrations of sialic acids (total, lipid bound and protein bound and their correlation with acute phase proteins (haptoglobin and serum amyloid A in clinical and subclinical mastitis of cattle. Thirty subclinical mastitic cows with positive California mastitis test (CMT test and no clinical signs of mastitis, 10 clinical mastitic cows and 10 healthy cows with negative CMT test and normal somatic cell count were selected. Milk and blood samples were collected after confirmation of clinical and subclinical mastitis by somatic cell count and bacterial identification. Serum haptoglobin (Hp, serum amyloid A (SAA, total sialic acid (TSA, lipid bound sialic acid (LBSA and protein bound sialic acid (PBSA were measured by validated standard methods. Haptoglobin and SAA increased significantly in both types of mastitis compared with control group (P<0.001. However, the ratio of HP/SAA was significantly different from the control group only in clinical mastitis. The results showed that TSA and LBSA were significantly different in control group compared with clinical and subclinical mastitis (P<0.001. Protein bound sialic acid did not change in subclinical mastitis in comparison with control group (P=0.86. There was positive correlation between LBSA and PBSA in clinical mastitis (r=0.72, P=0.02 whereas significant negative correlation was observed between LBSA and PBSA in subclinical mastitis (r=-0.62, P<0.001. Results also showed no correlation between Hp and SAA with each other or with any other parameters in study groups.

  13. Porcine Sapelovirus Uses α2,3-Linked Sialic Acid on GD1a Ganglioside as a Receptor

    Science.gov (United States)

    Kim, Deok-Song; Son, Kyu-Yeol; Koo, Kyung-Min; Kim, Ji-Yun; Alfajaro, Mia Madel; Park, Jun-Gyu; Hosmillo, Myra; Soliman, Mahmoud; Baek, Yeong-Bin; Cho, Eun-Hyo; Lee, Ju-Hwan; Kang, Mun-Il

    2016-01-01

    ABSTRACT The receptor(s) for porcine sapelovirus (PSV), which causes diarrhea, pneumonia, polioencephalomyelitis, and reproductive disorders in pigs, remains largely unknown. Given the precedent for other picornaviruses which use terminal sialic acids (SAs) as receptors, we examined the role of SAs in PSV binding and infection. Using a variety of approaches, including treating cells with a carbohydrate-destroying chemical (NaIO4), mono- or oligosaccharides (N-acetylneuraminic acid, galactose, and 6′-sialyllactose), linkage-specific sialidases (neuraminidase and sialidase S), lectins (Maakia amurensis lectin and Sambucus nigra lectin), proteases (trypsin and chymotrypsin), and glucosylceramide synthase inhibitors (dl-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol and phospholipase C), we demonstrated that PSV could recognize α2,3-linked SA on glycolipids as a receptor. On the other hand, PSVs had no binding affinity for synthetic histo-blood group antigens (HBGAs), suggesting that PSVs could not use HBGAs as receptors. Depletion of cell surface glycolipids followed by reconstitution studies indicated that GD1a ganglioside, but not other gangliosides, could restore PSV binding and infection, further confirming α2,3-linked SA on GD1a as a PSV receptor. Our results could provide significant information on the understanding of the life cycle of sapelovirus and other picornaviruses. For the broader community in the area of pathogens and pathogenesis, these findings and insights could contribute to the development of affordable, useful, and efficient drugs for anti-sapelovirus therapy. IMPORTANCE The porcine sapelovirus (PSV) is known to cause enteritis, pneumonia, polioencephalomyelitis, and reproductive disorders in pigs. However, the receptor(s) that the PSV utilizes to enter host cells remains largely unknown. Using a variety of approaches, we showed that α2,3-linked terminal sialic acid (SA) on the cell surface GD1a ganglioside could be used for PSV

  14. Analysis of monosaccharides, fatty constituents and rare O-acetylated sialic acids from gonads of the starfish Asterias rubens.

    Science.gov (United States)

    Zanetta, Jean-Pierre; Srinivasan, Vinayaga; Schauer, Roland

    2006-02-01

    A previous study (Bergwerff et al., Biochimie 74 (1992) 25-37) reported that sialic acids present in Asterias rubens gonads were essentially composed of 8-methyl-N-glycolylneuraminic acid (Neu5Gc8Me), a large part of it being acetylated in position 9. Using GC/MS of heptafluorobutyrate derivatives (Zanetta et al., Glycobiology 11 (2001) 663-676) on the chloroform/methanol soluble and insoluble fractions, we showed that most sialic acids were found in the latter and demonstrated that all sialic acids were derived from N-glycolylneuraminic acid, most of them being 8-methylated, but that the majority were also acetylated in position 4 or 7 (or both positions). GC/MS analyses of the constituents liberated using acid-catalysed methanolysis verified that major glycoprotein-bound glycans were N-linked and of the gluco-oligomannosidic type. Major fatty acids were poly-unsaturated (especially C20:4) and long-chain bases were C22:1 phytosphingosine and C22:2 6-hydroxysphingenine. Major monosaccharides found in the chloroform/methanol extract (quinovose and fucose) were derived from steroidal saponins.

  15. Sialic acid-containing sugar chains of hen ovalbumin and ovomucoid.

    Science.gov (United States)

    Yamashita, K; Tachibana, Y; Hitoi, A; Kobata, A

    1984-07-15

    The acidic oligosaccharide fractions released from hen ovalbumin and ovomucoid by hydrazinolysis contain both sialyloligosaccharides and sulfated oligosaccharides. The sialyloligosaccharides were converted into neutral oligosaccharides by sialidase digestion, and separated from sulfated oligosaccharides by paper electrophoresis. Structural studies of these neutral oligosaccharides showed that the oligosaccharides of ovalbumin have different structural characteristics from those of ovomucoid, i.e., all sialyloligosaccharides from ovomucoid contain a pentasaccharide, alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-beta-D-Manp -(1----4)-GlcpNAc- (1----4)-GlcpNAc, as a common core, and the smallest oligomannosyl core of the sugar chains from ovalbumin is alpha-D-Manp-(1----3)-alpha-D-Manp-(1----6)-[alpha-D-Manp -(1----3)]-beta-D- Manp-(1----4)-GlcpNAc-(1----4)-GlcpNAc. By methanolysis followed by N-acetylation, sialyl oligosaccharides, free from sulfated oligosaccharides, were recovered quantitatively from the acidic fractions of ovalbumin and ovomucoid. Methylation analysis of these sialyloligosaccharide mixtures, before and after sialidase digestion, showed that all sialic acid of both glycoproteins occurs as a alpha-Sia-(2----3)-D-Galp group.

  16. Serum and saliva sialic acid in periodontitis patients with and without cardiovascular disease.

    Science.gov (United States)

    Oktay, Sehkar; Basar, Isık; Emekli-Alturfan, Ebru; Malali, Ezgi; Elemek, Eser; Ayan, Faruk; Koldas, Lale; Noyan, Ulku; Emekli, Nesrin

    2010-01-01

    Serum total sialic acid (sTSA) has recently been shown to be a cardiovascular risk factor. However, there is little information about the role of sTSA and TSA in saliva in periodontitis, a chronic and inflammatory disease known to be a risk factor for cardiovascular disease (CVD). We aimed to investigate the changes in sTSA and TSA levels in saliva in patients having both periodontitis and CVD versus periodontitis patients without diagnosed CVD. The study group consisted of 26 patients with proven periodontitis and 26 controls with no diagnosed systemic disease but periodontitis. sTSA and saliva TSA levels were determined by the thiobarbituric acid method, and C-reactive protein (CRP) was evaluated by the nephelometric method. The severity of periodontitis has been determined by the community periodontal index of treatment needs (CPITN). TSA in blood and saliva and CRP levels in blood were significantly increased in CVD patients compared with the control group. CPITN ranged from 2 to 4 in both groups. Significant and positive correlations were found between sTSA and saliva SA levels in patients and controls and between tooth loss and TSA both in blood and saliva. Therefore, TSA in saliva may be a useful marker similar to sTSA in CVD patients.

  17. Comparative distribution of human and avian type sialic acid influenza receptors in the pig

    Directory of Open Access Journals (Sweden)

    Perez Belinda

    2010-01-01

    Full Text Available Abstract Background A major determinant of influenza infection is the presence of virus receptors on susceptible host cells to which the viral haemagglutinin is able to bind. Avian viruses preferentially bind to sialic acid α2,3-galactose (SAα2,3-Gal linked receptors, whereas human strains bind to sialic acid α2,6-galactose (SAα2,6-Gal linked receptors. To date, there has been no detailed account published on the distribution of SA receptors in the pig, a model host that is susceptible to avian and human influenza subtypes, thus with potential for virus reassortment. We examined the relative expression and spatial distribution of SAα2,3-GalG(1-3GalNAc and SAα2,6-Gal receptors in the major organs from normal post-weaned pigs by binding with lectins Maackia amurensis agglutinins (MAA II and Sambucus nigra agglutinin (SNA respectively. Results Both SAα2,3-Gal and SAα2,6-Gal receptors were extensively detected in the major porcine organs examined (trachea, lung, liver, kidney, spleen, heart, skeletal muscle, cerebrum, small intestine and colon. Furthermore, distribution of both SA receptors in the pig respiratory tract closely resembled the published data of the human tract. Similar expression patterns of SA receptors between pig and human in other major organs were found, with exception of the intestinal tract. Unlike the limited reports on the scarcity of influenza receptors in human intestines, we found increasing presence of SAα2,3-Gal and SAα2,6-Gal receptors from duodenum to colon in the pig. Conclusions The extensive presence of SAα2,3-Gal and SAα2,6-Gal receptors in the major organs examined suggests that each major organ may be permissive to influenza virus entry or infection. The high similarity of SA expression patterns between pig and human, in particular in the respiratory tract, suggests that pigs are not more likely to be potential hosts for virus reassortment than humans. Our finding of relative abundance of SA receptors

  18. Asthma induction in mice leads to appearance of alpha2-3- and alpha2-6-linked sialic acid residues in respiratory goblet-like cells

    DEFF Research Database (Denmark)

    Kirkeby, Svend; Jensen, Niels-Erik Viby; Mandel, Ulla;

    2008-01-01

    to demonstrate binding of lectins and antibodies that detect alpha2-3- and alpha2-6-linked sialic acid residues. After sensitization and challenge, the histology of the lung changed markedly, and goblet-like cells appeared, most likely caused by Clara cell metaplasia. Normal Clara cells showed no reaction after......Allergic asthmatic inflammation in mice was induced by sensitization with ovalbumin and lipopolysaccharide from Escherichia coli and visualized in the airways of asthmatic mice by spatial and temporal changes of carbohydrates containing sialic acid residues. Immunohistochemistry was used...... incubation with the sialic acid detecting agents, while the goblet-like cells expressed both alpha2-3- and alpha2-6-linked sialic acid residues in the asthmatic animals. The lectins but not the antibodies reacted with intestinal goblet cells. Instead, an antibody recognizing a disialoganglioside, stained...

  19. Application of a protocol for the detection of disorders of sialic acid metabolism to 124 high-risk Brazilian patients.

    Science.gov (United States)

    Castilhos, Cristina D; Mello, Alexandre S; Burin, Maira G; Guidobono, Régis R; Gotardo, Silvane; Giugliani, Roberto; Coelho, Janice C

    2003-06-15

    Lysosomal storage disorders (LSD) present great clinical variability. Included in this group are sialic acid metabolism disorders (SAMD). In the present study, we describe the application of a 3-step protocol for the diagnosis of SAMD, including (1). oligosaccharide and sialyloligosaccharide chromatography; (2). quantitative determination of sialic acid; and (3). measurement of neuraminidase activity. Application of our protocol to 124 individuals at risk for SAMD led to the diagnosis of five affected patients, two with type I sialidosis, one with type II sialidosis, and two with galactosialidosis. Due to its simplicity and efficiency, we propose the use of this protocol for the diagnostic evaluation of patients with suspected SAMD, which could be specially useful to non-specialized laboratories and to services located in developing countries.

  20. Host-Derived Sialic Acids Are an Important Nutrient Source Required for Optimal Bacterial Fitness In Vivo

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    Nathan D. McDonald

    2016-04-01

    Full Text Available A major challenge facing bacterial intestinal pathogens is competition for nutrient sources with the host microbiota. Vibrio cholerae is an intestinal pathogen that causes cholera, which affects millions each year; however, our knowledge of its nutritional requirements in the intestinal milieu is limited. In this study, we demonstrated that V. cholerae can grow efficiently on intestinal mucus and its component sialic acids and that a tripartite ATP-independent periplasmic SiaPQM strain, transporter-deficient mutant NC1777, was attenuated for colonization using a streptomycin-pretreated adult mouse model. In in vivo competition assays, NC1777 was significantly outcompeted for up to 3 days postinfection. NC1777 was also significantly outcompeted in in vitro competition assays in M9 minimal medium supplemented with intestinal mucus, indicating that sialic acid uptake is essential for fitness. Phylogenetic analyses demonstrated that the ability to utilize sialic acid was distributed among 452 bacterial species from eight phyla. The majority of species belonged to four phyla, Actinobacteria (members of Actinobacillus, Corynebacterium, Mycoplasma, and Streptomyces, Bacteroidetes (mainly Bacteroides, Capnocytophaga, and Prevotella, Firmicutes (members of Streptococcus, Staphylococcus, Clostridium, and Lactobacillus, and Proteobacteria (including Escherichia, Shigella, Salmonella, Citrobacter, Haemophilus, Klebsiella, Pasteurella, Photobacterium, Vibrio, and Yersinia species, mostly commensals and/or pathogens. Overall, our data demonstrate that the ability to take up host-derived sugars and sialic acid specifically allows V. cholerae a competitive advantage in intestinal colonization and that this is a trait that is sporadic in its occurrence and phylogenetic distribution and ancestral in some genera but horizontally acquired in others.

  1. Significance of serum fucose, sialic acid, haptoglobine and phospholipids levels in the evolution and treatment of breast cancer.

    Science.gov (United States)

    Kiricuta, I; Bojan, O; Comes, R; Cristian, R

    1979-01-01

    Serum fucose, sialic acid, haptoglobine and phospholipids were determined in 167 women with breast cancer stages I--III, 30 with benign lesions of the breast, 42 women in various physiological states of the mammary gland (pregnancy, early childbed and lactation) and compared with 30 healthy women as control. Serial determinations of these parameters during the radio-surgical treatment were done in 28 patients with breast cancer stage III. Fucose and phospholipids levels were significantly increased respectively decreased in the group of patients with breast cancers but unmodified in the others. Sialic acid and haptoglobine -- increased in patients with cancer -- were also elevated in patients with early childbed and benign affections of the breast. The surveillance of these four parameters during the radio-surgical treatment of breast cancer evidenced a good correlation between their modified levels and clinical state of the patients. The increase in fucose, sialic acid and haptoglobine respectively the decrease in phospholipids levels was associated with the clinical evidence of recurrences and metastases.

  2. Expression, solubilisation, and purification of a functional CMP-sialic acid transporter in Pichia pastoris.

    Science.gov (United States)

    Maggioni, Andrea; Hadley, Barbara; von Itzstein, Mark; Tiralongo, Joe

    2014-09-01

    Membrane proteins, including solute transporters play crucial roles in cellular function and have been implicated in a variety of important diseases, and as such are considered important targets for drug development. Currently the drug discovery process is heavily reliant on the structural and functional information discerned from high-resolution crystal structures. However, membrane protein structure determination is notoriously difficult, due in part to challenges faced in their expression, solubilisation and purification. The CMP-sialic acid transporter (CST) is considered to be an attractive target for drug discovery. CST inhibition reduces cancer cell sialylation and decreases the metastatic potential of cancer cells and to date, no crystal structure of the CST, or any other nucleotide sugar transporter exists. Here we describe the optimised conditions for expression in Pichia pastoris, solubilisation using n-nonyl β-d-maltopyranoside (NM) and single step purification of a functional CST. Importantly we show that despite being able to solubilise and purify the CST using a number of different detergents, only NM was able to maintain CST functionality.

  3. Purification and molecular characterization of a sialic acid specific lectin from the phytopathogenic fungus Macrophomina phaseolina.

    Science.gov (United States)

    Bhowal, Jayati; Guha, Arun Kumar; Chatterjee, Bishnu Pada

    2005-09-05

    A lectin was isolated and purified from the culture filtrate of the plant pathogenic fungus Macrophomina phaseolina by a combination of ammonium sulfate precipitation, affinity chromatography on fetuin-Sepharose 4B and ion-exchange chromatography on DEAE-A 50. The lectin designated MPL was homogeneous by PAGE and HPLC and a monomeric protein with a molecular weight of approximately 34 kDa as demonstrated by SDS-PAGE. It is a glycoprotein and agglutinated human erythrocytes regardless of the human blood type. Neuraminidase treatment of erythrocytes reduced the agglutination activity of the lectin. It is thermally stable and exhibits maximum activity between pH 6 and 7.2. Its carbohydrate binding specificity was investigated both by hapten inhibition of hemagglutination and by enzyme-conjugated lectin inhibition assay. Although, M. phaseolina lectin bound sialic acid, it exhibited binding affinity towards neuraminyl oligosaccharides of N-linked glycoproteins, alpha-Neu5Ac-(2-->3)-beta-Gal-(1-->4)-GlcNAc being maximum.

  4. N-acetylgalactosamine, N-acetylglucosamine and sialic acid expression in primary breast cancers.

    Science.gov (United States)

    Brooks, S A; Carter, T M

    2001-02-01

    Binding of the lectin from Helix pomatia (HPA), which recognises N-acetylgalactosamine and N-acetylglucosamine glycans, is a predictor of metastasis and poor prognosis in a number of human adenocarcinomas, including breast cancer. The glycoproteins to which it binds in these tumours have been only partially characterised, and the mechanisms underlying their biosynthesis remain unknown. In this study, 111 primary breast cancers were assessed for binding of HPA and labelling characteristics were compared directly with those of Dolichos biflorus agglutinin and soybean agglutinin, both of which also recognise N-acetylgalactosamine, Griffonia simplicifolia agglutinin II, which recognises N-acetylglucosamine, and Limax flavus agglutinin, Sambucus nigra agglutinin and Maackia amurensis lectin I, all of which recognise sialic acids. Results indicate that the HPA-binding partners expressed by cancer cells are predominantly N-acetylgalactosamine glycans, but some recognition of N-acetylglucosamine species is also likely. There was no evidence to support the hypothesis that overexpression of these moieties results from failure in sialylation. Alternative mechanisms, for example alterations in levels of activity of appropriate glycosyl transferases or disruption in transport and processing mechanisms leading to failure of normal chain extension of glycans may be responsible, and these are areas that warrant further investigation.

  5. Targeting sialic acid dependent and independent pathways of invasion in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Rosalynn Louise Ord

    Full Text Available The pathology of malaria is a consequence of the parasitaemia which develops through the cyclical asexual replication of parasites in a patient's red blood cells. Multiple parasite ligand-erythrocyte receptor interactions must occur for successful Plasmodium invasion of the human red cell. Two major malaria ligand families have been implicated in these variable ligand-receptor interactions used by Plasmodium falciparum to invade human red cells: the micronemal proteins from the Erythrocyte Binding Ligands (EBL family and the rhoptry proteins from the Reticulocyte binding Homolog (PfRH family. Ligands from the EBL family largely govern the sialic acid (SA dependent pathways of invasion and the RH family ligands (except for RH1 mediate SA independent invasion. In an attempt to dissect out the invasion inhibitory effects of antibodies against ligands from both pathways, we have used EBA-175 and RH5 as model members of each pathway. Mice were immunized with either region II of EBA-175 produced in Pichia pastoris or full-length RH5 produced by the wheat germ cell-free system, or a combination of the two antigens to look for synergistic inhibitory effects of the induced antibodies. Sera obtained from these immunizations were tested for native antigen recognition and for efficacy in invasion inhibition assays. Results obtained show promise for the potential use of such hybrid vaccines to induce antibodies that can block multiple parasite ligand-red cell receptor interactions and thus inhibit parasite invasion.

  6. Sialic acid expression in the mosquito Aedes aegypti and its possible role in dengue virus-vector interactions.

    Science.gov (United States)

    Cime-Castillo, Jorge; Delannoy, Philippe; Mendoza-Hernández, Guillermo; Monroy-Martínez, Verónica; Harduin-Lepers, Anne; Lanz-Mendoza, Humberto; Hernández-Hernández, Fidel de la Cruz; Zenteno, Edgar; Cabello-Gutiérrez, Carlos; Ruiz-Ordaz, Blanca H

    2015-01-01

    Dengue fever (DF) is the most prevalent arthropod-borne viral disease which affects humans. DF is caused by the four dengue virus (DENV) serotypes, which are transmitted to the host by the mosquito Aedes aegypti that has key roles in DENV infection, replication, and viral transmission (vector competence). Mosquito saliva also plays an important role during DENV transmission. In this study, we detected the presence of sialic acid (Sia) in Aedes aegypti tissues, which may have an important role during DENV-vector competence. We also identified genome sequences encoding enzymes involved in Sia pathways. The cDNA for Aedes aegypti CMP-Sia synthase (CSAS) was amplified, cloned, and functionally evaluated via the complementation of LEC29.Lec32 CSAS-deficient CHO cells. AedesCSAS-transfected LEC29.Lec32 cells were able to express Sia moieties on the cell surface. Sequences related to α-2,6-sialyltransferase were detected in the Aedes aegypti genome. Likewise, we identified Sia-α-2,6-DENV interactions in different mosquito tissues. In addition, we evaluated the possible role of sialylated molecules in a salivary gland extract during DENV internalization in mammalian cells. The knowledge of early DENV-host interactions could facilitate a better understanding of viral tropism and pathogenesis to allow the development of new strategies for controlling DENV transmission.

  7. Sialic Acid Expression in the Mosquito Aedes aegypti and Its Possible Role in Dengue Virus-Vector Interactions

    Science.gov (United States)

    Cime-Castillo, Jorge; Delannoy, Philippe; Mendoza-Hernández, Guillermo; Monroy-Martínez, Verónica; Lanz-Mendoza, Humberto; Hernández-Hernández, Fidel de la Cruz; Cabello-Gutiérrez, Carlos; Ruiz-Ordaz, Blanca H.

    2015-01-01

    Dengue fever (DF) is the most prevalent arthropod-borne viral disease which affects humans. DF is caused by the four dengue virus (DENV) serotypes, which are transmitted to the host by the mosquito Aedes aegypti that has key roles in DENV infection, replication, and viral transmission (vector competence). Mosquito saliva also plays an important role during DENV transmission. In this study, we detected the presence of sialic acid (Sia) in Aedes aegypti tissues, which may have an important role during DENV-vector competence. We also identified genome sequences encoding enzymes involved in Sia pathways. The cDNA for Aedes aegypti CMP-Sia synthase (CSAS) was amplified, cloned, and functionally evaluated via the complementation of LEC29.Lec32 CSAS-deficient CHO cells. AedesCSAS-transfected LEC29.Lec32 cells were able to express Sia moieties on the cell surface. Sequences related to α-2,6-sialyltransferase were detected in the Aedes aegypti genome. Likewise, we identified Sia-α-2,6-DENV interactions in different mosquito tissues. In addition, we evaluated the possible role of sialylated molecules in a salivary gland extract during DENV internalization in mammalian cells. The knowledge of early DENV-host interactions could facilitate a better understanding of viral tropism and pathogenesis to allow the development of new strategies for controlling DENV transmission. PMID:25874215

  8. Sialic Acid Expression in the Mosquito Aedes aegypti and Its Possible Role in Dengue Virus-Vector Interactions

    Directory of Open Access Journals (Sweden)

    Jorge Cime-Castillo

    2015-01-01

    Full Text Available Dengue fever (DF is the most prevalent arthropod-borne viral disease which affects humans. DF is caused by the four dengue virus (DENV serotypes, which are transmitted to the host by the mosquito Aedes aegypti that has key roles in DENV infection, replication, and viral transmission (vector competence. Mosquito saliva also plays an important role during DENV transmission. In this study, we detected the presence of sialic acid (Sia in Aedes aegypti tissues, which may have an important role during DENV-vector competence. We also identified genome sequences encoding enzymes involved in Sia pathways. The cDNA for Aedes aegypti CMP-Sia synthase (CSAS was amplified, cloned, and functionally evaluated via the complementation of LEC29.Lec32 CSAS-deficient CHO cells. AedesCSAS-transfected LEC29.Lec32 cells were able to express Sia moieties on the cell surface. Sequences related to α-2,6-sialyltransferase were detected in the Aedes aegypti genome. Likewise, we identified Sia-α-2,6-DENV interactions in different mosquito tissues. In addition, we evaluated the possible role of sialylated molecules in a salivary gland extract during DENV internalization in mammalian cells. The knowledge of early DENV-host interactions could facilitate a better understanding of viral tropism and pathogenesis to allow the development of new strategies for controlling DENV transmission.

  9. Co-expression of sialic acid receptors compatible with avian and human influenza virus binding in emus (Dromaius novaehollandiae).

    Science.gov (United States)

    Gujjar, Naveen; Chothe, Shubhada K; Gawai, Shashikant; Nissly, Ruth; Bhushan, Gitanjali; Kanagaraj, Vijayarani; Jayarao, Bhushan M; Kathaperumal, Kumanan; Subbiah, Madhuri; Kuchipudi, Suresh V

    2017-01-01

    Influenza A viruses (IAVs) continue to threaten animal and human health with constant emergence of novel variants. While aquatic birds are a major reservoir of most IAVs, the role of other terrestrial birds in the evolution of IAVs is becoming increasingly evident. Since 2006, several reports of IAV isolations from emus have surfaced and avian influenza infection of emus can lead to the selection of mammalian like PB2-E627K and PB2-D701N mutants. However, the potential of emus to be co-infected with avian and mammalian IAVs is not yet understood. As a first step, we investigated sialic acid (SA) receptor distribution across major organs and body systems of emu and found a widespread co-expression of both SAα2,3Gal and SAα2,6Gal receptors in various tissues that are compatible with avian and human IAV binding. Our results suggest that emus could allow genetic recombination and hence play an important role in the evolution of IAVs. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. The role of functionally defective rare germline variants of sialic acid acetylesterase in autoimmune Addison's disease

    Science.gov (United States)

    Gan, Earn H; MacArthur, Katie; Mitchell, Anna L; Pearce, Simon H S

    2012-01-01

    Background Autoimmune Addison's disease (AAD) is a rare condition with a complex genetic basis. A panel of rare and functionally defective genetic variants in the sialic acid acetylesterase (SIAE) gene has recently been implicated in several common autoimmune conditions. We performed a case–control study to determine whether these rare variants are associated with a rarer condition, AAD. Method We analysed nine SIAE gene variants (W48X, M89V, C196F, C226G, R230W, T312M, Y349C, F404S and R479C) in a United Kingdom cohort of 378 AAD subjects and 387 healthy controls. All samples were genotyped using Sequenom iPlex chemistry to characterise primer extension products. Results A heterozygous rare allele at codon 312 (312*M) was found in one AAD patient (0.13%) but was not detected in the healthy controls. The commoner, functionally recessive variant at codon 89 (89*V) was found to be homozygous in two AAD patients but was only found in the heterozygous state in controls. Taking into account all nine alleles examined, 4/378 (1.06%) AAD patients and 1/387 (0.25%) healthy controls carried the defective SIAE alleles, with a calculated odds ratio of 4.13 (95% CI 0.44–97.45, two-tailed P value 0.212, NS). Conclusion We demonstrated the presence of 89*V homozygotes and the 312*M rare allele in the AAD cohort, but overall, our analysis does not support a role for rare variants in SIAE in the pathogenesis of AAD. However, the relatively small collection of AAD patients limits the power to exclude a small effect. PMID:23011869

  11. Evaluation of lipid-bound sialic acid (LSA) as a tumor marker.

    Science.gov (United States)

    López Sáez, J J; Senra-Varela, A

    1995-01-01

    The objective of this study is the evaluation of serum levels of lipid-bound sialic acid (LSA) as a of marker cancer. This is a case-control study, and the levels of LSA were determined with blinded duplicates of cases and controls. Histologic verification of all cancer cases was used to confirm the diagnosis. The study included 135 patients with cancer (breast carcinoma, head and neck squamous cell carcinoma, lung cancer and gastrointestinal cancer) and 95 controls (57 normal subjects and 38 with chronic non-malignant diseases). Marker determination was done by the spectrophotometric procedure of Katopodis with resorcinol. The mean LSA level in the 57 healthy individuals was 15.09 mg/dl(95% C.I., 13.51-16.67), in the entire control group of 95 non-tumoral individuals it was 19.21 mg/dl (17.18-21.24), and in the 135 cancer patients it was 26.64 mg/dl (24.42-28.87). There was a statistically significant difference between patients with chronic non-tumoral diseases and healthy individuals (p 0.001), but not between cancer patients and patients with chronic non-tumoral diseases (p> 0.05). The mean LSA serum values related to tumor site were (mg/dl): breast cancer, 21.49; gastrointestinal tumors, 28.45; head and neck cancer, 28.61 and lung cancer, 32.54. The means according to clinical stage were: complete remission, 18.50 significantly higher than the healthy controls (p< 0.05); local disease, 23.50 (p < 0.01); locoregional disease, (p < 0.05); local disease, 23.50 (p < 0.01); locoregional disease, 27.21 (p < 0.001); metastatic disease, 34.49 (p < 0.001), and relapses, 20.87 (p< 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Clinical significance of sialic acid in acute rheumatic fever with and without carditis

    Directory of Open Access Journals (Sweden)

    Maher H. Gomaa

    2012-08-01

    Full Text Available Objective: In Egypt, acute rheumatic fever (ARF is the most common cause of acquired heart disease. ARF is a clinical syndrome without a specific diagnostic test or single pathognomonic feature, so the aim of this study is to investigate the utility of using serum total sialic acid (TSA in differentiation between children suffering from ARF with and without carditis. Methods: In the present study, 62 children were divided into three groups: first group, 16 healthy children; second group, 20 patients suffering from chronic rheumatic heart disease (RHD; and third group, 26 patients suffering from ARF, subdivided into three subgroups as (A 10 patients suffering from arthritis without carditis, (B 10 patients with carditis but without congestive heart failure (CHF, and (C 6 patients with carditis and CHF. Antistreptolysin O titre (ASOT by latex agglutination test, erythrocyte sedimentation rate (ESR by Westergren method, C-reactive protein (CRP by turbidimetric immunoassay method, lactate dehydrogenase (LDH activity by kinetic method, immunoglobulin levels by radial immunodifussion assay (RID, cardiac troponin I (cTnI by ELISA test kit and TSA by diphenylamine (DPA method were performed. Results: Significant elevated values of ESR, CRP, LDH, IgG and IgA were obtained in ARF as compared to both control and RHD groups; significant values of IgM were found between B and C as compared to control and RHD groups; cTnI showed insignificant difference between all groups; values of TSA showed highly significant difference between ARF as compared to both control and RHD groups as well as between RHD and control groups; significant difference was found between B and C groups as compared to group A. Conclusion: The results of the present study point out the possibility that the levels of TSA could be of help in differentiation between ARF patients with and without carditis. [J Exp Integr Med 2012; 2(4: 305-311

  13. α2,3 and α2,6 N-Linked Sialic Acids Facilitate Efficient Binding and Transduction by Adeno-Associated Virus Types 1 and 6

    Science.gov (United States)

    Wu, Zhijian; Miller, Edward; Agbandje-McKenna, Mavis; Samulski, Richard Jude

    2006-01-01

    Recombinant adeno-associated viruses (AAVs) are promising vectors in the field of gene therapy. Different AAV serotypes display distinct tissue tropism, believed to be related to the distribution of their receptors on target cells. Of the 11 well-characterized AAV serotypes, heparan sulfate proteoglycan and sialic acid have been suggested to be the attachment receptors for AAV type 2 and types 4 and 5, respectively. In this report, we identify the receptor for the two closely related serotypes, AAV1 and AAV6. First, we demonstrate using coinfection experiments and luciferase reporter analysis that AAV1 and AAV6 compete for similar receptors. Unlike heparin sulfate, enzymatic or genetic removal of sialic acid markedly reduced AAV1 and AAV6 binding and transduction. Further analysis using lectin staining and lectin competition assays identified that AAV1 and AAV6 use either α2,3-linked or α2,6-linked sialic acid when transducing numerous cell types (HepG2, Pro-5, and Cos-7). Treatment of cells with proteinase K but not glycolipid inhibitor reduced AAV1 and AAV6 infection, supporting the hypothesis that the sialic acid that facilitates infection is associated with glycoproteins rather than glycolipids. In addition, we determined by inhibitor (N-benzyl GalNAc)- and cell line-specific (Lec-1) studies that AAV1 and AAV6 require N-linked and not O-linked sialic acid. Furthermore, a resialylation experiment on a deficient Lec-2 cell line confirmed a 2,3 and 2,6 N-linked sialic acid requirement, while studies of mucin with O-linked sialic acid showed no inhibition effect for AAV1 and AAV6 transduction on Cos-7 cells. Finally, using a glycan array binding assay we determined that AAV1 efficiently binds to NeuAcα2-3GalNAcβ1-4GlcNAc, as well as two glycoproteins with α2,3 and α2,6 N-linked sialic acids. Taken together, competition, genetic, inhibitor, enzymatic reconstitution, and glycan array experiments support α2,3 and α2,6 sialic acids that are present on N

  14. Analysis of the changes in expression levels of sialic acid on influenza-virus-infected cells using lectin-tagged polymeric nanoparticles

    Directory of Open Access Journals (Sweden)

    Jaebum Cho

    2016-07-01

    Full Text Available Viral infections affect millions around the world, sometimes leading to severe consequences or even epidemics. Understanding the molecular dynamics during viral infections would provide crucial information for preventing or stopping the progress of infections. However, the current methods often involve the disruption of the infected cells or expensive and time-consuming procedures. In this study, fluorescent polymeric nanoparticles were fabricated and used as bioimaging nanoprobes that can monitor the progression of influenza viral infection through the changes in the expression levels of sialic acids expressed on the cell membrane. The nanoparticles were composed of a biocompatible monomer to prevent non-specific interactions, a hydrophobic monomer to form the core, a fluorescent monomer, and a protein-binding monomer to conjugate lectin, which binds sialic acids. It was shown that these lectin-tagged nanoparticles that specifically target sialic acids could track the changes in the expression levels of sialic acids caused by influenza viral infections in human lung epithelial cells. There was a sudden drop in the levels of sialic acid at the initial onset of virus infection (t = 0~1 hr and at approximately 4~5 hrs post-infection. The latter drop correlated with the production of viral proteins that was confirmed using traditional techniques. Thus, the accuracy, the rapidity and the efficacy of the nanoprobes were demonstrated. Such molecular bioimaging tools, which allow easy-handling and in situ monitoring, would be useful to directly observe and decipher the viral infection mechanisms.

  15. The nutritional role of free sialic acid, a human milk monosaccharide, and its application as a functional food ingredient.

    Science.gov (United States)

    Röhrig, Christoph H; Choi, Sharon S H; Baldwin, Nigel

    2017-03-24

    N-Acetyl-d-neuraminic acid (NANA), more commonly known by its trivial name sialic acid, is an endogenous human and ubiquitous nutritional monosaccharide. As a bound sugar at the terminal positions of glycans NANA is known to play important roles in many biological events. The data that exist on the occurrence of the free monosaccharide in breast milk and nutrition, however, are less commonly discussed. In most foods of animal origin, sialic acid occurs as a mixture of NANA and N-glycolyl-d-neuraminic acid (NGNA), a hydroxylated derivative of NANA that is not found in humans. The dietary intake of NGNA has been identified as a risk factor for long-term adverse health effects. Therefore, we present summaries on the biochemistry, metabolism, bioavailability, and the data on NANA and NGNA levels that occur in diverse foods. Finally, we discuss the emerging data demonstrating that free NANA is linked to positive nutritional effects including pronounced antioxidative properties. These data and the extremely high safety profile of NANA justify dietary enrichment at levels that correspond to the dietary intake of NANA in infants through breast milk.

  16. A sialic acid-specific lectin from the mushroom Paecilomyces Japonica that exhibits hemagglutination activity and cytotoxicity.

    Science.gov (United States)

    Park, Jee Hun; Ryu, Chang Soo; Kim, Ha Na; Na, Young Jun; Park, Hyun Joo; Kim, Hahyung

    2004-12-01

    The mushroom Paecilomyces japonica, grown on the silkworm larvae, has been used in Asia as a nutraceutical, tea, and Chinese medicine. In the present study, a sialic acid-specific lectin has been purified from the mushroom P. japonica using affinity chromatography on a fetuin-agarose column. Electrophoretical analyses indicated that this lectin, designated P. japonica agglutinin (PJA), is an acidic protein with a molecular mass of 16 kDa, and has no intermolecular disulfide bonds. PJA induced hemagglutination activity in human ABO, mouse, rat, and rabbit erythrocytes. This activity was inhibited by sialic acid and sialoglycoproteins, but not by any other carbohydrates. PJA was stable at pH 4.0-8.0, and at temperatures below 55 degrees C. The activity of PJA was independent of EDTA and divalent cations. In addition, PJA exerts cytotoxic effects on the following cancer cell lines: human stomach cancer SNU-1, human pancreas cancer AsPc-1, and human breast cancer MDA-MB-231.

  17. The correlations among serum tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and sialic acids with peripheral lymphocytes in bovine tropical theileriosis.

    Science.gov (United States)

    Razavi, Seyed Mostafa; Nazifi, Saeed; Emadi, Mahboobeh; Rakhshandehroo, Ehsan

    2010-10-01

    The infection with protozoan parasite Theileria annulata induces changes triggering the activation and/or proliferation of the host lymphocytes. In order to find out the possible correlations among peripheral circulatory lymphocytes, cytokine activities and the level of sialic acids, 50 dairy Holstein cattle, naturally infected with T. annulata, were divided into 4 subgroups according to their parasitemia rates (5%). Also, ten non-infected cattle were sampled as control group. Blood samples were taken from jugular vein into acid citrate dextrose-containing tubes for measuring hematological parameters and B and T (CD(4) and CD(8)) cell populations and without anticoagulant for TNF-alpha, IFN-gamma and sialic acid concentrations. Remarkable decreases observed in red blood cells (RBCs), white blood cells (WBCs) and packed cell volume (PCV) in infected cattle compared to healthy ones (P < 0.05). Also, with increase in parasitemia rate, total lymphocytes and monocytes alleviated in the diseased groups. By contrast, total neutrohpils and the concentrations of TNF-alpha, IFN-gamma and total sialic acids were significantly elevated (P < 0.05) in infected animals. Accordingly, the circulatory populations of CD(4) and CD(8) T cells and B cells showed a substantial decrease, while a significant increase was observed in T (CD(4) and CD(8)) cells in cattle infected with <1% parasitemia rates. Decreased circulatory T cell population shows the ineffective responses of T cells to the stimulatory cytokines such as IFN-gamma or TNF-alpha. On the other hand, the elevation of cytokines (particularly IFN-gamma) and sialic acids have presumably an inhibitory role on circulatory B cell population in infected cattle. In addition, a high level of sialic acid concentration indicates the probable role of sialic acid to regulate the parasite-host cell adhesion during sporozoites invasion.

  18. Biochemical engineering of the N-acyl side chain of sialic acids alters the kinetics of a glycosylated potassium channel Kv3.1.

    Science.gov (United States)

    Hall, M Kristen; Reutter, Werner; Lindhorst, Thisbe; Schwalbe, Ruth A

    2011-10-20

    The sialic acid of complex N-glycans can be biochemically engineered by substituting the physiological precursor N-acetylmannosamine with non-natural N-acylmannosamines. The Kv3.1 glycoprotein, a neuronal voltage-gated potassium channel, contains sialic acid. Western blots of the Kv3.1 glycoprotein isolated from transfected B35 neuroblastoma cells incubated with N-acylmannosamines verified sialylated N-glycans attached to the Kv3.1 glycoprotein. Outward ionic currents of Kv3.1 transfected B35 cells treated with N-pentanoylmannosamine or N-propanoylmannosamine had slower activation and inactivation rates than those of untreated cells. Therefore, the N-acyl side chain of sialic acid is intimately connected with the activation and inactivation rates of this glycosylated potassium channel.

  19. Automation of High-Throughput Mass Spectrometry-Based Plasma N-Glycome Analysis with Linkage-Specific Sialic Acid Esterification.

    Science.gov (United States)

    Bladergroen, Marco R; Reiding, Karli R; Hipgrave Ederveen, Agnes L; Vreeker, Gerda C M; Clerc, Florent; Holst, Stephanie; Bondt, Albert; Wuhrer, Manfred; van der Burgt, Yuri E M

    2015-09-04

    Glycosylation is a post-translational modification of key importance with heterogeneous structural characteristics. Previously, we have developed a robust, high-throughput MALDI-TOF-MS method for the comprehensive profiling of human plasma N-glycans. In this approach, sialic acid residues are derivatized with linkage-specificity, namely the ethylation of α2,6-linked sialic acid residues with parallel lactone formation of α2,3-linked sialic acids. In the current study, this procedure was used as a starting point for the automation of all steps on a liquid-handling robot system. This resulted in a time-efficient and fully standardized procedure with throughput times of 2.5 h for a first set of 96 samples and approximately 1 h extra for each additional sample plate. The mass analysis of the thus-obtained glycans was highly reproducible in terms of relative quantification, with improved interday repeatability as compared to that of manual processing.

  20. Inhibition of basophil histamine release by gangliosides. Further studies on the significance of cell membrane sialic acid in the histamine release process

    DEFF Research Database (Denmark)

    Jensen, C; Norn, S; Thastrup, Ole

    1987-01-01

    with the glucolipid mixture increased the sialic acid content of the cells, and this increase was attributed to an insertion of gangliosides into the cell membrane. The inhibition of histamine release was abolished by increasing the calcium concentration, which substantiates our previous findings that cell membrane......Histamine release from human basophils was inhibited by preincubation of the cells with a glucolipid mixture containing sialic acid-containing gangliosides. This was true for histamine release induced by anti-IgE, Concanavalin A and the calcium ionophore A23187, whereas the release induced by S....... aureus Wood 46 was not affected. It was demonstrated that the inhibitory capacity of the glucolipid mixture could be attributed to the content of gangliosides, since no inhibition was obtained with cerebrosides or with gangliosides from which sialic acid was removed. Preincubation of the cells...

  1. Protein-bound carbohydrates in breast cancer. Liquid-chromatographic analysis for mannose, galactose, fucose, and sialic acid in serum.

    Science.gov (United States)

    Mrochek, J E; Dinsmore, S R; Tormey, D C; Waalkes, T P

    1976-09-01

    We describr high-resolution chromatographic analysis for protein-bound sialic acid in serum, with use of a cerate oxidimetric detector. Values for sera from normal women averaged 680.5 mg/liter, with a coefficient of variation of 23%. Including data obtained by previously developed chromatographic procedures for protein-bound mannose, galactose, and fucsoe, we assessed sera from breast-cancer patients whose malignancy had been categorized as either stable, responsive, or progressive (based on clinical observations spaced from two to five months apart). All of 12 responsive patients had decreases of protein-bound fucose averaging 34.5% (SD, 16.1) and all of 10 patients with progressive disease had increases averaging 38.3% (SD 21.5). Changes in fucose averaged less than 6.7% (SD, 4.9) for eight patients with clinically stable breast cancer. Changes in protein-bound mannose, galactose, and sialic acid did not correlate as well as did fucose with the clinical disease status of the patients.

  2. Protein-bound carbohydrates in breast cancer. Liquid-chromatographic analysis for mannose, galactose, fucose, and sialic acid in serum

    Energy Technology Data Exchange (ETDEWEB)

    Mrochek, J.E. (Oak Ridge National Lab., TN); Dinsmore, S.R.; Tormey, D.C.; Waalkes, T.P.

    1976-09-01

    High-resolution chromatographic analysis for protein-bound sialic acid in serum, with use of a cerate oxidimetric detector is described. Values for sera from normal women averaged 680.5 mg/liter, with a coefficient of variation of 23%. Including data obtained by previously developed chromatographic procedures for protein-bound mannose, galactose, and fucose, sera from breast-cancer patients whose malignancy had been categorized as either stable, responsive, or progressive (based on clinical observations spaced from two to five months apart) were assessed. All of 12 responsive patients had decreases of protein-bound fucose averaging 34.5% (SD, 16.1) and all of 10 patients with progressive disease had increases averaging 38.3% (SD 21.5). Changes in fucose averaged less than 6.7% (SD, 4.9) for eight patients with clinically stable breast cancer. Changes in protein-bound mannose, galactose, and sialic acid did not correlate as well as did fucose with the clinical disease status of the patients.

  3. Enzymatic Decoration of Prebiotic Galacto-oligosaccharides (Vivinal® GOS) with Sialic Acid using Trypanosoma cruzi Trans-Sialidase and Two Bovine Sialoglycoconjugates as Donor Substrates

    NARCIS (Netherlands)

    Wilbrink, Maarten Hotse; Ten Kate, Geert Albert; Sanders, Peter; Gerwig, Gerrit J; van Leeuwen, Sander S; Sallomons, Erik; Klarenbeek, Bert; Hage, Johannes H; van Vuure, Carine A; Dijkhuizen, Lubbert; Kamerling, Johannis P

    2015-01-01

    Decoration of prebiotic galacto-oligosaccharides (GOS) with sialic acid yields mixtures of GOS and sialylated GOS (Sia-GOS), novel products that are expected to have both prebiotic and anti-adhesive functionalities. The recombinantly produced trans-sialidase enzyme from Trypanosoma cruzi (TcTS), an

  4. Microscale Measurements of Michaelis-Menten Constants of Neuraminidase with Nanogel Capillary Electrophoresis for the Determination of the Sialic Acid Linkage.

    Science.gov (United States)

    Gattu, Srikanth; Crihfield, Cassandra L; Holland, Lisa A

    2017-01-03

    Phospholipid nanogels enhance the stability and performance of the exoglycosidase enzyme neuraminidase and are used to create a fixed zone of enzyme within a capillary. With nanogels, there is no need to covalently immobilize the enzyme, as it is physically constrained. This enables rapid quantification of Michaelis-Menten constants (KM) for different substrates and ultimately provides a means to quantify the linkage (i.e., 2-3 versus 2-6) of sialic acids. The fixed zone of enzyme is inexpensive and easily positioned in the capillary to support electrophoresis mediated microanalysis using neuraminidase to analyze sialic acid linkages. To circumvent the limitations of diffusion during static incubation, the incubation period is reproducibly achieved by varying the number of forward and reverse passes the substrate makes through the stationary fixed zone using in-capillary electrophoretic mixing. A KM value of 3.3 ± 0.8 mM (Vmax, 2100 ± 200 μM/min) was obtained for 3'-sialyllactose labeled with 2-aminobenzoic acid using neuraminidase from Clostridium perfringens that cleaves sialic acid monomers with an α2-3,6,8,9 linkage, which is similar to values reported in the literature that required benchtop analyses. The enzyme cleaves the 2-3 linkage faster than the 2-6, and a KM of 2 ± 1 mM (Vmax, 400 ± 100 μM/min) was obtained for the 6'-sialyllactose substrate. An alternative neuraminidase selective for 2-3 sialic acid linkages generated a KM value of 3 ± 2 mM (Vmax, 900 ± 300 μM/min) for 3'-sialyllactose. With a knowledge of Vmax, the method was applied to a mixture of 2-3 and 2-6 sialyllactose as well as 2-3 and 2-6 sialylated triantennary glycan. Nanogel electrophoresis is an inexpensive, rapid, and simple alternative to current technologies used to distinguish the composition of 3' and 6' sialic acid linkages.

  5. Distribution of sialic acid receptors and influenza A viruses of avian and swine origin and in experimentally infected pigs

    DEFF Research Database (Denmark)

    Trebbien, Ramona; Larsen, Lars Erik; Viuff, Birgitte M.

    2011-01-01

    , and II, and Sambucus Nigra (SNA). Furthermore, the predilection sites of swine influenza virus (SIV) subtypes H1N1 and H1N2 as well as avian influenza virus (AIV) subtype H4N6 were investigated in the respiratory tract of experimentally infected pigs using immunohistochemical methods. Results: SIV......Background: Pigs are considered susceptible to influenza A virus infections from different host origins because earlier studies have shown that they have receptors for both avian (sialic acid-alpha-2,3-terminal saccharides (SAalpha- 2,3)) and swine/human (SA-alpha-2,6) influenza viruses...... in the upper respiratory tract. Furthermore, experimental and natural infections in pigs have been reported with influenza A virus from avian and human sources. Methods: This study investigated the receptor distribution in the entire respiratory tract of pigs using specific lectins Maackia Amurensis (MAA) I...

  6. Sialic acid transport and catabolism are cooperatively regulated by SiaR and CRP in nontypeable Haemophilus influenzae

    Directory of Open Access Journals (Sweden)

    Johnston Jason W

    2010-09-01

    Full Text Available Abstract Background The transport and catabolism of sialic acid, a critical virulence factor for nontypeable Haemophilus influenzae, is regulated by two transcription factors, SiaR and CRP. Results Using a mutagenesis approach, glucosamine-6-phosphate (GlcN-6P was identified as a co-activator for SiaR. Evidence for the cooperative regulation of both the sialic acid catabolic and transport operons suggested that cooperativity between SiaR and CRP is required for regulation. cAMP was unable to influence the expression of the catabolic operon in the absence of SiaR but was able to induce catabolic operon expression when both SiaR and GlcN-6P were present. Alteration of helical phasing supported this observation by uncoupling SiaR and CRP regulation. The insertion of one half-turn of DNA between the SiaR and CRP operators resulted in the loss of SiaR-mediated repression of the transport operon while eliminating cAMP-dependent induction of the catabolic operon when GlcN-6P was present. SiaR and CRP were found to bind to their respective operators simultaneously and GlcN-6P altered the interaction of SiaR with its operator. Conclusions These results suggest multiple novel features for the regulation of these two adjacent operons. SiaR functions as both a repressor and an activator and SiaR and CRP interact to regulate both operons from a single set of operators.

  7. Terminal sialic acids on CD44 N-glycans can block hyaluronan binding by forming competing intramolecular contacts with arginine sidechains

    Science.gov (United States)

    Faller, Christina E.; Guvench, Olgun

    2014-01-01

    Specific sugar residues and their linkages form the basis of molecular recognition for interactions of glycoproteins with other biomolecules. Seemingly small changes, like the addition of a single monosaccharide in the covalently attached glycan component of glycoproteins, can greatly affect these interactions. For instance, the sialic acid capping of glycans affects protein-ligand binding involved in cell-cell and cell-matrix interactions. CD44 is a single-pass transmembrane glycoprotein whose binding with its carbohydrate ligand hyaluronan (HA), an extracellular matrix component, mediates processes such as leukocyte homing, cell adhesion, and tumor metastasis. This binding is highly regulated by glycosylation of the N-terminal extracellular hyaluronan-binding domain (HABD); specifically, sialic acid capped N-glycans of HABD inhibit ligand binding. However, the molecular mechanism behind this sialic acid mediated regulation has remained unknown. Two of the five N-glycosyation sites of HABD have been previously identified as having the greatest inhibitory effect on HA binding, but only if the glycans contain terminal sialic acid residues. These two sites, Asn25 and Asn120, were chosen for in silico glycosylation in this study. Here, from extensive standard molecular dynamics simulations and biased simulations, we propose a molecular mechanism for this behavior based on spontaneously-formed charge-paired hydrogen bonding interactions between the negatively-charged sialic acid residues and positively-charged Arg sidechains known to be critically important for binding to HA, which itself is negatively charged. Such intramolecular hydrogen bonds would preclude associations critical to hyaluronan binding. This observation suggests how CD44 and related glycoprotein binding is regulated by sialylation as cellular environments fluctuate. PMID:25116630

  8. Affinity purification of the voltage-sensitive sodium channel from electroplax with resins selective for sialic acid

    Energy Technology Data Exchange (ETDEWEB)

    James, W.M.; Emerick, M.C.; Agnew, W.S. (Yale Univ. School of medicine, New Haven, CT (USA))

    1989-07-11

    The voltage-sensitive sodium channel present in the eel (Electrophorus electricus) has an unusually high content of sialic acid, including {alpha}-(2{yields}8)-linked polysialic acid, not found in other electroplax membrane glycopeptides. Lectins from Limax flavus (LFA) and wheat germ (WGA) proved the most effective of 11 lectin resins tried. The most selective resin was prepared from IgM antibodies against Neisseria meningitidis {alpha}-(2{yields}8)-polysialic acid which were affinity purified and coupled to Sepharose 4B. The sodium channel was found to bind to WGA, LFA, and IgM resins and was readily eluted with the appropriate soluble carbohydrates. Experiments with LFA and IgM resins demonstrated binding and unbinding rates and displacement kinetics, which suggest highly specific binding at multiple sites on the sodium channel protein. In preparative-scale purification of protein previously fractionated by anion-exchange chromatography, without stabilizing TTX, high yields were reproducibly obtained. Further, when detergent extracts were prepared from electroplax membranes fractionated by low-speed sedimentation, a single step over the IgM resin provided a 70-fold purification, yielding specific activities of 3,200 pmol of ({sup 3}H)TTX-binding sites/mg of protein and a single polypeptide of {approximately}285,000 Da on SDS-acrylamide gels. No small peptides were observed after this 5-h isolation. The authors describe a cation-dependent stabilization with millimolar levels of monovalent and micromolar levels of divalent species.

  9. Both α2,3- and α2,6-linked sialic acids on O-linked glycoproteins act as functional receptors for porcine Sapovirus.

    Directory of Open Access Journals (Sweden)

    Deok-Song Kim

    2014-06-01

    Full Text Available Sapovirus, a member of the Caliciviridae family, is an important cause of acute gastroenteritis in humans and pigs. Currently, the porcine sapovirus (PSaV Cowden strain remains the only cultivable member of the Sapovirus genus. While some caliciviruses are known to utilize carbohydrate receptors for entry and infection, a functional receptor for sapovirus is unknown. To characterize the functional receptor of the Cowden strain of PSaV, we undertook a comprehensive series of protein-ligand biochemical assays in mock and PSaV-infected cell culture and/or piglet intestinal tissue sections. PSaV revealed neither hemagglutination activity with red blood cells from any species nor binding activity to synthetic histo-blood group antigens, indicating that PSaV does not use histo-blood group antigens as receptors. Attachment and infection of PSaV were markedly blocked by sialic acid and Vibrio cholerae neuraminidase (NA, suggesting a role for α2,3-linked, α2,6-linked or α2,8-linked sialic acid in virus attachment. However, viral attachment and infection were only partially inhibited by treatment of cells with sialidase S (SS or Maackia amurensis lectin (MAL, both specific for α2,3-linked sialic acid, or Sambucus nigra lectin (SNL, specific for α2,6-linked sialic acid. These results indicated that PSaV recognizes both α2,3- and α2,6-linked sialic acids for viral attachment and infection. Treatment of cells with proteases or with benzyl 4-O-β-D-galactopyranosyl-β-D-glucopyranoside (benzylGalNAc, which inhibits O-linked glycosylation, also reduced virus binding and infection, whereas inhibition of glycolipd synthesis or N-linked glycosylation had no such effect on virus binding or infection. These data suggest PSaV binds to cellular receptors that consist of α2,3- and α2,6-linked sialic acids on glycoproteins attached via O-linked glycosylation.

  10. Both α2,3- and α2,6-linked sialic acids on O-linked glycoproteins act as functional receptors for porcine Sapovirus.

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    Kim, Deok-Song; Hosmillo, Myra; Alfajaro, Mia Madel; Kim, Ji-Yun; Park, Jun-Gyu; Son, Kyu-Yeol; Ryu, Eun-Hye; Sorgeloos, Frederic; Kwon, Hyung-Jun; Park, Su-Jin; Lee, Woo Song; Cho, Duck; Kwon, Joseph; Choi, Jong-Soon; Kang, Mun-Il; Goodfellow, Ian; Cho, Kyoung-Oh

    2014-06-01

    Sapovirus, a member of the Caliciviridae family, is an important cause of acute gastroenteritis in humans and pigs. Currently, the porcine sapovirus (PSaV) Cowden strain remains the only cultivable member of the Sapovirus genus. While some caliciviruses are known to utilize carbohydrate receptors for entry and infection, a functional receptor for sapovirus is unknown. To characterize the functional receptor of the Cowden strain of PSaV, we undertook a comprehensive series of protein-ligand biochemical assays in mock and PSaV-infected cell culture and/or piglet intestinal tissue sections. PSaV revealed neither hemagglutination activity with red blood cells from any species nor binding activity to synthetic histo-blood group antigens, indicating that PSaV does not use histo-blood group antigens as receptors. Attachment and infection of PSaV were markedly blocked by sialic acid and Vibrio cholerae neuraminidase (NA), suggesting a role for α2,3-linked, α2,6-linked or α2,8-linked sialic acid in virus attachment. However, viral attachment and infection were only partially inhibited by treatment of cells with sialidase S (SS) or Maackia amurensis lectin (MAL), both specific for α2,3-linked sialic acid, or Sambucus nigra lectin (SNL), specific for α2,6-linked sialic acid. These results indicated that PSaV recognizes both α2,3- and α2,6-linked sialic acids for viral attachment and infection. Treatment of cells with proteases or with benzyl 4-O-β-D-galactopyranosyl-β-D-glucopyranoside (benzylGalNAc), which inhibits O-linked glycosylation, also reduced virus binding and infection, whereas inhibition of glycolipd synthesis or N-linked glycosylation had no such effect on virus binding or infection. These data suggest PSaV binds to cellular receptors that consist of α2,3- and α2,6-linked sialic acids on glycoproteins attached via O-linked glycosylation.

  11. Human influenza A virus hemagglutinin distinguishes sialyloligosaccharides in membrane-associated gangliosides as its receptor which mediates the adsorption and fusion processes of virus infection. Specificity for oligosaccharides and sialic acids and the sequence to which sialic acid is attached.

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    Suzuki, Y; Nagao, Y; Kato, H; Matsumoto, M; Nerome, K; Nakajima, K; Nobusawa, E

    1986-12-25

    Human influenza A virus isolates bearing antigenically different H1 (A/PR/8/34), H2 (A/Japan/305/57), and H3 (A/Aichi/2/68, A/X-31) hemagglutinin serotypes caused extensive hemagglutination, low pH fusion, and hemolysis of asialoerythrocytes reconstituted with gangliosides. Sialylparaglobosides (IV3NeuAc-nLc4Cer, IV6NeuAc-nLc4Cer), I-active and i-active (VI3NeuAc-nLc6Cer) gangliosides, and GM3-NeuAc commonly exhibited significant specific receptor activity toward the viruses. A/PR/8/34 recognized IV3NeuAc-nLc4Cer containing the NeuAc alpha 2-3Gal sequence preferentially over IV6NeuAc-nLc4Cer containing NeuAc alpha 2-6Gal, whereas the other two recognized the NeuAc alpha 2-6Gal sequence preferentially over NeuAc alpha 2-3Gal. Responsiveness of erythrocytes labeled with gangliosides containing NeuGc to the viruses used was considerably lower than that of erythrocytes labeled with gangliosides containing NeuAc. The activities of GM1a, GM2, and GD1b bearing NeuAc on inner galactose of the ganglio series core were also very low. These results indicate that sialyloligosaccharides of IV3NeuAc-nLc4Cer, IV6NeuAc-nLc4Cer, I-active ganglioside, and VI3NeuAc-nLc6Cer in addition to GM3-NeuAc and GM1b-NeuAc (Suzuki, Y., Matsunaga, M., and Matsumoto, M. (1985), J. Biol. Chem. 260, 1362-1365; Suzuki, Y., Matsunaga, M., Nagao, Y., Taki, T., Hirabayashi, Y., and Matsumoto, M. (1985) Vaccine 3, 201-203) are functional receptor determinants toward hemagglutinin of human influenza A viruses, and the viruses differentiate microdomains of the gangliosides, such as the sialic acid species (NeuAc, NeuGc) and the sequence of sialic acid linkages (NeuAc alpha 2-3Gal, NeuAc alpha 2-6Gal).

  12. Hemagglutinin protein of Asian strains of human influenza virus A H1N1 binds to sialic acid--a major component of human airway receptors.

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    Chua, K H; Chai, H C

    2012-03-16

    Hemagglutinin (HA) protein plays an important role in binding the influenza virus to infected cells and therefore mediates infection. Deposited HA sequences of 86 Asian strains of influenza A (H1N1) viruses during the first outbreak were obtained from the NCBI database and compared. Interaction of the HA protein of influenza A (H1N1) virus with the human sialic acid receptor was also studied using bioinformatics. Overall, not more than three single-point amino acid variants/changes were observed in the HA protein region of influenza A (H1N1) virus from Asian countries when a selected group sequence comparison was made. The bioinformatics study showed that the HA protein of influenza A (H1N1) binds to the sialic acid receptor in human airway receptors, possibly key to air-borne infection in humans.

  13. Comparison of the nature of interactions of two sialic acid specific lectins Saraca indica and Sambucus nigra with N-acetylneuraminic acid by spectroscopic techniques

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    Singha, Shuvendu [Department of Natural Science, West Bengal University of Technology, Kolkata 700064 (India); Department of Chemistry, Jadavpur University, Jadavpur, Kolkata 700032 (India); Bose, Partha P. [Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Hajipur 844101 (India); Ganguly, Tapan [School of Laser Science and Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Campana, Patricia T. [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, 03828-000 São Paulo (Brazil); Ghosh, Rina [Department of Chemistry, Jadavpur University, Jadavpur, Kolkata 700032 (India); Chatterjee, Bishnu P., E-mail: cbishnup@gmail.com [Department of Natural Science, West Bengal University of Technology, Kolkata 700064 (India)

    2015-04-15

    The present paper deals with the isolation and purification of a new sialic acid binding lectin from the seed integument of Saraca indica (Ashok) and the purified lectin was designated Saracin II. Comparative studies on the interactions of saracin II and another sialic acid specific lectin Sambucus nigra agglutinin (SNA) with N-acetylneuraminic acid (NANA) were made using UV–vis absorption, steady state and time resolved fluorescence along with circular dichroism (CD) spectroscopy to reveal the nature and mechanisms of binding of these two lectins with NANA. The experimental observations obtained from UV–vis, steady state and time resolved fluorescence measurements demonstrated that SNA–NANA system formed relatively stronger ground state complex than saracin II–NANA pair. CD measurements further substantiated the propositions made from steady state and time resolved spectroscopic investigations. It was inferred that during interaction of SNA with NANA, the lectin adopted a relatively looser conformation with the extended polypeptide structures leading to the exposure of the hydrophobic cavities which favoured stronger binding with NANA. - Highlights: • Of the two lectins, stronger binding of SNA with NANA is observed. • Full exposure of the hydrophobic cavities of SNA favors the stronger interactions. • Saracin II can be used for the new generation of lectin based-therapeutics.

  14. Replication of avian, human and swine influenza viruses in porcine respiratory explants and association with sialic acid distribution

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    Nauwynck Hans J

    2010-02-01

    Full Text Available Abstract Background Throughout the history of human influenza pandemics, pigs have been considered the most likely "mixing vessel" for reassortment between human and avian influenza viruses (AIVs. However, the replication efficiencies of influenza viruses from various hosts, as well as the expression of sialic acid (Sia receptor variants in the entire porcine respiratory tract have never been studied in detail. Therefore, we established porcine nasal, tracheal, bronchial and lung explants, which cover the entire porcine respiratory tract with maximal similarity to the in vivo situation. Subsequently, we assessed virus yields of three porcine, two human and six AIVs in these explants. Since our results on virus replication were in disagreement with the previously reported presence of putative avian virus receptors in the trachea, we additionally studied the distribution of sialic acid receptors by means of lectin histochemistry. Human (Siaα2-6Gal and avian virus receptors (Siaα2-3Gal were identified with Sambucus Nigra and Maackia amurensis lectins respectively. Results Compared to swine and human influenza viruses, replication of the AIVs was limited in all cultures but most strikingly in nasal and tracheal explants. Results of virus titrations were confirmed by quantification of infected cells using immunohistochemistry. By lectin histochemistry we found moderate to abundant expression of the human-like virus receptors in all explant systems but minimal binding of the lectins that identify avian-like receptors, especially in the nasal, tracheal and bronchial epithelium. Conclusions The species barrier that restricts the transmission of influenza viruses from one host to another remains preserved in our porcine respiratory explants. Therefore this system offers a valuable alternative to study virus and/or host properties required for adaptation or reassortment of influenza viruses. Our results indicate that, based on the expression of Sia

  15. NanR, a Transcriptional Regulator That Binds to the Promoters of Genes Involved in Sialic Acid Metabolism in the Anaerobic Pathogen Clostridium perfringens.

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    Blair Therit

    Full Text Available Among many other virulence factors, Clostridium perfringens produces three sialidases NanH, NanI and NanJ. NanH lacks a secretion signal peptide and is predicted to be an intracellular enzyme, while NanI and NanJ are secreted. Previously, we had identified part of an operon encoding NanE (epimerase and NanA (sialic acid lyase enzymes. Further analysis of the entire operon suggests that it encodes a complete pathway for the transport and metabolism of sialic acid along with a putative transcriptional regulator, NanR. The addition of 30 mM N-acetyl neuraminic acid (Neu5Ac to a semi-defined medium significantly enhanced the growth yield of strain 13, suggesting that Neu5Ac can be used as a nutrient. C. perfringens strain 13 lacks a nanH gene, but has NanI- and NanJ-encoding genes. Analysis of nanI, nanJ, and nanInanJ mutants constructed by homologous recombination revealed that the expression of the major sialidase, NanI, was induced by the addition of Neu5Ac to the medium, and that in separate experiments, the same was true of a nanI-gusA transcriptional fusion. For the nanI and nanJ genes, primer extension identified three and two putative transcription start sites, respectively. Gel mobility shift assays using purified NanR and DNA from the promoter regions of the nanI and nanE genes showed high affinity, specific binding by NanR. We propose that NanR is a global regulator of sialic acid-associated genes and that it responds, in a positive feedback loop, to the concentration of sialic acid in the cell.

  16. M89V Sialic acid Acetyl Esterase (SIAE) and all other non-synonymous common variants of this gene are catalytically normal.

    Science.gov (United States)

    Chellappa, Vasant; Taylor, Kendra N; Pedrick, Kathryn; Donado, Carlos; Netravali, Ilka Arun; Haider, Khaleda; Cariappa, Annaiah; Dalomba, Natasha F; Pillai, Shiv

    2013-01-01

    Catalytically defective rare variants of Sialic acid Acetyl Esterase (SIAE) have previously been linked to autoimmunity. Studies presented here confirm that the M89V SIAE protein and all other products of common variant alleles of SIAE are catalytically normal. Although overexpressing transfected non-lymphoid cells secrete small amounts of SIAE that can associate with the cell surface, normal human lymphocytes do not exhibit cell surface SIAE, supporting genetic evidence in mice that indicates that this protein functions in a lymphocyte intrinsic manner. Analyses of the plasma proteome also indicate that SIAE is not secreted in vivo. A re-analysis exclusively of catalytically defective rare variant alleles of SIAE in subjects in which this gene was completely sequenced confirmed an association of SIAE with autoimmunity. A subset of catalytically defective rare variant SIAE alleles has previously been typed in a large genotyping study comparing a diverse group of disease subjects and controls; our re-analysis of this data shows that catalytically defective alleles are enriched in disease subjects. These data suggest that SIAE may be associated with autoimmunity and that further study of catalytically defective rare variant SIAE alleles in terms of autoimmune disease susceptibility is strongly warranted.

  17. M89V Sialic acid Acetyl Esterase (SIAE and all other non-synonymous common variants of this gene are catalytically normal.

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    Vasant Chellappa

    Full Text Available Catalytically defective rare variants of Sialic acid Acetyl Esterase (SIAE have previously been linked to autoimmunity. Studies presented here confirm that the M89V SIAE protein and all other products of common variant alleles of SIAE are catalytically normal. Although overexpressing transfected non-lymphoid cells secrete small amounts of SIAE that can associate with the cell surface, normal human lymphocytes do not exhibit cell surface SIAE, supporting genetic evidence in mice that indicates that this protein functions in a lymphocyte intrinsic manner. Analyses of the plasma proteome also indicate that SIAE is not secreted in vivo. A re-analysis exclusively of catalytically defective rare variant alleles of SIAE in subjects in which this gene was completely sequenced confirmed an association of SIAE with autoimmunity. A subset of catalytically defective rare variant SIAE alleles has previously been typed in a large genotyping study comparing a diverse group of disease subjects and controls; our re-analysis of this data shows that catalytically defective alleles are enriched in disease subjects. These data suggest that SIAE may be associated with autoimmunity and that further study of catalytically defective rare variant SIAE alleles in terms of autoimmune disease susceptibility is strongly warranted.

  18. Conservation of structure and mechanism in primary and secondary transporters exemplified by SiaP, a sialic acid binding virulence factor from Haemophilus influenzae.

    Science.gov (United States)

    Müller, Axel; Severi, Emmanuele; Mulligan, Christopher; Watts, Andrew G; Kelly, David J; Wilson, Keith S; Wilkinson, Anthony J; Thomas, Gavin H

    2006-08-04

    Extracytoplasmic solute receptors (ESRs) are important components of solute uptake systems in bacteria, having been studied extensively as parts of ATP binding cassette transporters. Herein we report the first crystal structure of an ESR protein from a functionally characterized electrochemical ion gradient dependent secondary transporter. This protein, SiaP, forms part of a tripartite ATP-independent periplasmic transporter specific for sialic acid in Haemophilus influenzae. Surprisingly, the structure reveals an overall topology similar to ATP binding cassette ESR proteins, which is not apparent from the sequence, demonstrating that primary and secondary transporters can share a common structural component. The structure of SiaP in the presence of the sialic acid analogue 2,3-didehydro-2-deoxy-N-acetylneuraminic acid reveals the ligand bound in a deep cavity with its carboxylate group forming a salt bridge with a highly conserved Arg residue. Sialic acid binding, which obeys simple bimolecular association kinetics as determined by stopped-flow fluorescence spectroscopy, is accompanied by domain closure about a hinge region and the kinking of an alpha-helix hinge component. The structure provides insight into the evolution, mechanism, and substrate specificity of ESR-dependent secondary transporters that are widespread in prokaryotes.

  19. Molecular characterization of the level of sialic acids N-acetylneuraminic acid, N-glycolylneuraminic acid, and ketodeoxynonulosonic acid in porcine milk during lactation.

    Science.gov (United States)

    Jahan, M; Wynn, P C; Wang, B

    2016-10-01

    Sialic acids (Sia) are key monosaccharide constituents of sialylated glycoproteins (Sia-GP), human sialylated milk oligosaccharide (Sia-MOS), and gangliosides. Human milk sialylated glycoconjugates (Sia-GC) are bioactive compounds known to act as prebiotics and promote neurodevelopment, immune function, and gut maturation in newborns. Only limited data are available on the Sia content of porcine milk. The objective of this study was to quantitatively determine the total level of Sia N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc), and ketodeoxynonulosonic acid (KDN) in porcine milk and to compare these levels in gilt and sow milk during lactation. Milk from 8 gilts and 22 sows was collected at 3 stages of lactation (colostrum, transition, and mature milk). Standard and experimental samples were derivatized using 1,2-diamino-4,5-methylenedioxy-benzene and analyzed by ultra-high-performance liquid chromatography using a fluorescence detector. The following new findings are reported: (1) Gilt and sow milk contained significant levels of total Sia, with the highest concentration in colostrum (1,238.5 mg/L), followed by transition milk (778.3 mg/L) and mature milk (347.2 mg/L); (2) during lactation, the majority of Sia was conjugated to Sia-GP (41-46%), followed by Sia-MOS (31-42%) and a smaller proportion in gangliosides (12-28%); (3) Neu5Ac was the major form of Sia (93-96%), followed by Neu5Gc (3-6%) and then KDN (1-2%), irrespective of milk fraction or stage of lactation; (4) the concentration of Sia in Sia-GP and Sia-MOS showed a significant decline during lactation, but the level of ganglioside Sia remained relatively constant; (5) mature gilt milk contained a significantly higher concentration of Sia-GP than sow milk. The high concentration of total Sia in porcine milk suggests that Sia-GC are important nutrients that contribute to the optimization of neurodevelopment, immune function, and growth and development in piglets. These findings

  20. Increased protein oxidation and loss of protein-bound sialic acid in hepatic tissues of D-galactose induced aged rats.

    Science.gov (United States)

    Cakatay, Ufuk; Aydın, Seval; Atukeren, Pınar; Yanar, Karolin; Sitar, Mustafa E; Dalo, Enis; Uslu, Ezel

    2013-07-01

    A redox basis of the increased oxidative protein damage and free radical-mediated desialylation have not been fully elucidated in aging. It is well known that the incidence of several liver diseases increase with age. This original research focuses on protein oxidation mechanisms and protein-bound sialic acid levels in liver tissue of the mimetic aging rats. Injection of D-galactose (60 mg/kg/day) for six weeks to male Sprague-Dawley rats (20-week-old) used to establish mimetic aging model. We investigated the tissue levels of various protein oxidation markers such as protein carbonyl groups, suitable advanced oxidation protein products and protein thiol groups. Our study also covered protein-bound sialic acid in liver tissue of D-galactose-induced aging rats. PCO (Protein Carbonyl Groups), P-OOH (Protein Hydroperoxides) and AOPP (Advanced Oxidation Protein Products) levels in aging rats were significantly higher compared to young control groups. On the other hand, P-SH (Protein Thiol Groups) levels were not found to be different between two groups. SA (Sialic Acid) levels in D-galactose-induced aging rats were significantly lower compared to control groups. Our results demonstrated greater susceptibility to hepatic oxidative protein damage and desialylation of hepatocellular proteins in Dgalactose- induced aging rats. These molecular mechanisms may be operative in the many age-related liver diseases, which are pertinent to increased oxidative stress and altered redox homeostasis.

  1. Mutation in the key enzyme of sialic acid biosynthesis causes severe glomerular proteinuria and is rescued by N-acetylmannosamine.

    Science.gov (United States)

    Galeano, Belinda; Klootwijk, Riko; Manoli, Irini; Sun, MaoSen; Ciccone, Carla; Darvish, Daniel; Starost, Matthew F; Zerfas, Patricia M; Hoffmann, Victoria J; Hoogstraten-Miller, Shelley; Krasnewich, Donna M; Gahl, William A; Huizing, Marjan

    2007-06-01

    Mutations in the key enzyme of sialic acid biosynthesis, uridine diphospho-N-acetylglucosamine 2-epimerase/N-acetylmannosamine (ManNAc) kinase (GNE/MNK), result in hereditary inclusion body myopathy (HIBM), an adult-onset, progressive neuromuscular disorder. We created knockin mice harboring the M712T Gne/Mnk mutation. Homozygous mutant (Gne(M712T/M712T)) mice did not survive beyond P3. At P2, significantly decreased Gne-epimerase activity was observed in Gne(M712T/M712T) muscle, but no myopathic features were apparent. Rather, homozygous mutant mice had glomerular hematuria, proteinuria, and podocytopathy. Renal findings included segmental splitting of the glomerular basement membrane, effacement of podocyte foot processes, and reduced sialylation of the major podocyte sialoprotein, podocalyxin. ManNAc administration yielded survival beyond P3 in 43% of the Gne(M712T/M712T) pups. Survivors exhibited improved renal histology, increased sialylation of podocalyxin, and increased Gne/Mnk protein expression and Gne-epimerase activities. These findings establish this Gne(M712T/M712T) knockin mouse as what we believe to be the first genetic model of podocyte injury and segmental glomerular basement membrane splitting due to hyposialylation. The results also support evaluation of ManNAc as a treatment not only for HIBM but also for renal disorders involving proteinuria and hematuria due to podocytopathy and/or segmental splitting of the glomerular basement membrane.

  2. Highly sensitive detection of influenza virus by boron-doped diamond electrode terminated with sialic acid-mimic peptide.

    Science.gov (United States)

    Matsubara, Teruhiko; Ujie, Michiko; Yamamoto, Takashi; Akahori, Miku; Einaga, Yasuaki; Sato, Toshinori

    2016-08-09

    The progression of influenza varies according to age and the presence of an underlying disease; appropriate treatment is therefore required to prevent severe disease. Anti-influenza therapy, such as with neuraminidase inhibitors, is effective, but diagnosis at an early phase of infection before viral propagation is critical. Here, we show that several dozen plaque-forming units (pfu) of influenza virus (IFV) can be detected using a boron-doped diamond (BDD) electrode terminated with a sialic acid-mimic peptide. The peptide was used instead of the sialyloligosaccharide receptor, which is the common receptor of influenza A and B viruses required during the early phase of infection, to capture IFV particles. The peptide, which was previously identified by phage-display technology, was immobilized by click chemistry on the BDD electrode, which has excellent electrochemical characteristics such as low background current and weak adsorption of biomolecules. Electrochemical impedance spectroscopy revealed that H1N1 and H3N2 IFVs were detectable in the range of 20-500 pfu by using the peptide-terminated BDD electrode. Our results demonstrate that the BDD device integrated with the receptor-mimic peptide has high sensitivity for detection of a low number of virus particles in the early phase of infection.

  3. Combined measurement and significance of lipid-bound sialic acid and carcinoembryonic antigen in detection of human cancer.

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    Munjal, D D; Picken, J; Pritchard, J

    1984-01-01

    We evaluated the clinical usefulness of lipid-bound sialic acid (LSA) as a "tumor marker" and assessed individual and carcinoembryonic antigen (CEA) in cancer patients. Serum LSA and CEA concentrations were measured by the resorcinol method after total lipid extraction and isolation of the sialolipid fraction, and by Abbott enzyme immunoassay procedures, respectively. Results indicate that the frequency of elevation and mean LSA values were highest in patients with lung cancer (318 mg/liter), intermediate in miscellaneous (210 mg/liter) and colorectal cancers (200 mg/liter), and lowest in breast cancer (175 mg/liter); while mean CEA values were highest in colorectal cancer (162.5 micrograms/liter), followed by lung (33.8 micrograms/liter), miscellaneous (30.3 micrograms/liter), and breast cancers (11.6 micrograms/liter). Statistically, LSA and CEA values for cancer patients were significantly (P less than 0.001) higher than for normal subjects. The combined measurement of LSA and CEA in serum provides better detection potential for cancer patients than either of the two markers alone.

  4. Individual and combined usefulness of lipid associated sialic acid, mucoid proteins and hexoses as tumor markers in breast carcinoma.

    Science.gov (United States)

    Patel, P S; Baxi, B R; Adhvaryu, S G; Balar, D B

    1990-06-15

    Serum levels of lipid associated sialic acid (LASA), mucoid proteins (MP) and hexoses (galactose + mannose) were measured in 41 breast cancer patients, 14 patients with benign breast diseases and 36 healthy age matched female individuals. In breast carcinoma patients, we have observed significant increase in the levels of the three markers compared with the controls (P less than 0.001) and in MP and hexoses compared to the patients with benign breast diseases (P less than 0.001). LASA and hexoses levels were significantly higher in benign breast diseases with respect to controls (P less than 0.001 and P less than 0.01, respectively). We evaluated the sensitivity and specificity of the markers individually and in combination. MP were most sensitive (71.8%) and specific (71.4%). Both sensitivity and specificity were increased when combinations of the markers were studied. Combination of MP with LASA was most sensitive (97.4%) while the combination of MP and hexoses was most specific (92.9%). LASA was significantly elevated in infiltrating duct carcinoma compared to lobular carcinoma (P less than 0.001). MP and hexoses also showed higher mean value in infiltrating duct carcinoma than lobular carcinoma. The present study suggests that the combination of the markers investigated might be useful for diagnosis and classification of breast carcinoma.

  5. A comparison of the effect of glitazones on serum sialic acid in patients with type 2 diabetes.

    Science.gov (United States)

    ur Rahman, Inayat; Idrees, Muhammad; Salman, Mohammad; Khan, Rooh Ullah; Khan, M I; Amin, Fazli; Jan, Naeem Ullah

    2012-07-01

    Although management of hyperglycaemia represents one of the principal treatment goals of diabetes therapy, the high incidence of cardiovascular (CV) complications in diabetes also needs effective management. Therefore, the present study was designed to determine and compare the effect of glitazones on serum sialic acid (SSA), a known risk marker for CV disease, along with fasting plasma glucose (FPG), glycohaemoglobin (HbA1-c) and blood lipids, in overweight, previously only diet-treated patients with type 2 diabetes (n=60). The study was conducted for a period of 12 months. Significant improvement in FPG and HbA1-c were shown by both rosiglitazone (ppioglitazone (ppioglitazone showed greater beneficial effects on other parameters monitored, significantly reducing total cholesterol (TC) (p≤0.05). Both the drugs showed a decrease in SSA and no significant differences were observed between the groups. However, the decrease was significant only in the pioglitazone-treated group at month 12 (p≤0.05), compared with baseline. A significant decrease in SSA by pioglitazone indicates its greater cardioprotective effect compared with rosiglitazone.

  6. Salivary Lipid Peroxidation and Total Sialic Acid Levels in Smokers and Smokeless Tobacco Users as Maraş Powder

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    Naciye Kurtul

    2012-01-01

    Full Text Available Maraş powder (MP, a different type of smokeless tobacco (ST and prepared from a tobacco of species Nicotiana rustica Linn, is widely used in Turkey. We aimed to investigate the effects of MP on salivary total sialic acid (TSA and malondialdehyde (MDA levels and to compare these parameters in smokers and MP users (MPUs. The salivary TSA and MDA concentrations were significantly higher in the smokers and MPU than those of control subjects and also in MPU than that of smokers. We have also observed that as the number of cigarettes consumed and MP amount increases, TSA and MDA levels increase too. In smokers, MDA values were significantly correlated with the number of cigarettes smoked and the duration of smoking. In MPU, both MDA and TSA levels were significantly correlated with the duration of MP use and the amount of daily consumed MP. We have concluded increased salivary TSA and MDA levels associated in MPU and smokers. Results can help to evaluate harmful effects of these habits. It is important to point out that bigger change in the measured parameters has been observed for MP use. This observation may be an important indication of harmful effects of ST use as MP.

  7. Catechins and Sialic Acid Attenuate Helicobacter pylori-Triggered Epithelial Caspase-1 Activity and Eradicate Helicobacter pylori Infection

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    Jyh-Chin Yang

    2013-01-01

    Full Text Available The inflammasome/caspase-1 signaling pathway in immune cells plays a critical role in bacterial pathogenesis; however, the regulation of this pathway in the gastric epithelium during Helicobacter pylori infection is yet to be elucidated. Here, we investigated the effect of catechins (CAs, sialic acid (SA, or combination of CA and SA (CASA on H. pylori-induced caspase-1-mediated epithelial damage, as well as H. pylori colonization in vitro (AGS cells and in vivo (BALB/c mice. Our results indicate that the activity of caspase-1 and the expression of its downstream substrate IL-1β were upregulated in H. pylori-infected AGS cells. In addition, we observed increased oxidative stress, NADPH oxidase gp91phox, CD68, caspase-1/IL-1β, and apoptosis, but decreased autophagy, in the gastric mucosa of H. pylori-infected mice. We have further demonstrated that treatment with CASA led to synergistic anti-H. pylori activity and was more effective than treatment with CA or SA alone. In particular, treatment with CASA for 10 days eradicated H. pylori infection in up to 95% of H. pylori-infected mice. Taken together, we suggest that the pathogenesis of H. pylori involves a gastric epithelial inflammasome/caspase-1 signaling pathway, and our results show that CASA was able to attenuate this pathway and effectively eradicate H. pylori infection.

  8. Microscale Measurements of Michaelis–Menten Constants of Neuraminidase with Nanogel Capillary Electrophoresis for the Determination of the Sialic Acid Linkage

    Science.gov (United States)

    2016-01-01

    Phospholipid nanogels enhance the stability and performance of the exoglycosidase enzyme neuraminidase and are used to create a fixed zone of enzyme within a capillary. With nanogels, there is no need to covalently immobilize the enzyme, as it is physically constrained. This enables rapid quantification of Michaelis–Menten constants (KM) for different substrates and ultimately provides a means to quantify the linkage (i.e., 2-3 versus 2-6) of sialic acids. The fixed zone of enzyme is inexpensive and easily positioned in the capillary to support electrophoresis mediated microanalysis using neuraminidase to analyze sialic acid linkages. To circumvent the limitations of diffusion during static incubation, the incubation period is reproducibly achieved by varying the number of forward and reverse passes the substrate makes through the stationary fixed zone using in-capillary electrophoretic mixing. A KM value of 3.3 ± 0.8 mM (Vmax, 2100 ± 200 μM/min) was obtained for 3′-sialyllactose labeled with 2-aminobenzoic acid using neuraminidase from Clostridium perfringens that cleaves sialic acid monomers with an α2-3,6,8,9 linkage, which is similar to values reported in the literature that required benchtop analyses. The enzyme cleaves the 2-3 linkage faster than the 2-6, and a KM of 2 ± 1 mM (Vmax, 400 ± 100 μM/min) was obtained for the 6′-sialyllactose substrate. An alternative neuraminidase selective for 2-3 sialic acid linkages generated a KM value of 3 ± 2 mM (Vmax, 900 ± 300 μM/min) for 3′-sialyllactose. With a knowledge of Vmax, the method was applied to a mixture of 2-3 and 2-6 sialyllactose as well as 2-3 and 2-6 sialylated triantennary glycan. Nanogel electrophoresis is an inexpensive, rapid, and simple alternative to current technologies used to distinguish the composition of 3′ and 6′ sialic acid linkages. PMID:27936604

  9. Expression, purification, crystallization and preliminary X-ray diffraction analysis of the VP8* sialic acid-binding domain of porcine rotavirus strain OSU

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang-De, E-mail: zhangyd1960@yahoo.com.cn; Li, Hao [National Hepatobiliary and Enteric Surgery Research Center of The Ministry of Health, Xiangya Hospital, Central South University, Hunan Province (China); Liu, Hui; Pan, Yi-Feng [Biochemistry Laboratory, Institution of Biomedical Engineering, Central South University, Hunan Province (China); National Hepatobiliary and Enteric Surgery Research Center of The Ministry of Health, Xiangya Hospital, Central South University, Hunan Province (China)

    2007-02-01

    Porcine rotavirus strain OSU VP8* domain has been expressed, purified and crystallized. X-ray diffraction data from different crystal forms of the VP8* domain have been collected to 2.65 and 2.2 Å resolution, respectively. The rotavirus outer capsid spike protein VP4 is utilized in the process of rotavirus attachment to and membrane penetration of host cells. VP4 is cleaved by trypsin into two domains: VP8* and VP5*. The VP8* domain is implicated in initial interaction with sialic acid-containing cell-surface carbohydrates and triggers subsequent virus invasion. The VP8* domain from porcine OSU rotavirus was cloned and expressed in Escherichia coli. Different crystal forms (orthorhombic P2{sub 1}2{sub 1}2{sub 1} and tetragonal P4{sub 1}2{sub 1}2) were harvested from two distinct crystallization conditions. Diffraction data have been collected to 2.65 and 2.2 Å resolution and the VP8*{sub 65–224} structure was determined by molecular replacement.

  10. BIOTRANSFORMATION USING RECOMBINANT CMP SIALIC ACID SYNTHETASE AND α-2, 6-SIALYLTRAN SFERASE: ENZYMATIC SYNTHESIS OF SIALOSIDES

    Directory of Open Access Journals (Sweden)

    Ulrike Hubl

    2012-01-01

    Full Text Available In this research, we successfully expressed recombinant CMP-sialic Acid Synthetase (CSS from Neisseria meningitides and 2,6-Sialyltransferase (SAT from Photobacterium damsela in E. coli BL21(DE3 fermented at a scale of up to 8 litres using individual plasmids pIRL-1 and pIRL-4b, respectively. After cell lysis with BugBuster, enzyme levels of 2U and 22U per litre were produced for CSS and SAT, respectively. The enzyme solutions were either used directly as crude preparations or further purified by affinity chromatography. Characterization of the CSS and SAT confirmed that both enzymes had comparable properties to those described in the literature. The production of cytidine 5’-monophosphate N-acetylneuraminic acid (CMP-NeuAc and CMP-9-azido-NeuAc using crude CSS was successful with >90% conversion at scales from 100 mg to 5 g. Activated sugar purification by ethanol precipitation was optimized. Finally, the CSS and SAT enzymes were applied to a large-scale synthesis of a sialylated lactosamine glycoside via a two-step biotransformation. The initial step employed crude CSS to convert Cytidine Triphosphate (CTP and 9-azido-NeuAc to CMP-9-azido-NeuAc at a conversion efficiency of 98%. This reaction mixture, after ultrafiltration to remove β-galactosidase activity co-expressed by E. coli BL21, was used as the donor substrate for the second step involving SAT. The sialoside 9-azido-sialyl-α-2,6’-lactosamine glycoside was produced with 86% conversion of the starting glycoside. Purification of the product was achieved by chromatography on Diaion HP-20 (a hydrophobic styrenic resin.

  11. Total sialic acid: an acute phase reactant in cats with a possible role in feline coronavirus infection.

    Science.gov (United States)

    Rossi, Gabriele; Paltrinieri, Saverio

    2009-04-01

    The aims of this study were to validate a colorimetric method to measure total sialic acid (TSA) in feline serum and to investigate the serum concentration of TSA in clinically healthy cats seronegative (n = 9) and seropositive (n = 48) for feline coronavirus (FCoV), and in cats affected by feline infectious peritonitis (FIP, n = 28), tumors (n = 20), or inflammation (n = 16). The correlation between TSA and alpha(1)-acid glycoprotein (AGP) was also investigated. The method employed in this study is precise and accurate at TSA levels (in mg/L) commonly encountered in feline serum. No significant differences between seropositive (385.6 +/- 192.2 mg/L) and seronegative (433.5 +/- 179.0 mg/L) cats were detectable, suggesting that the simple infection by FCoVs does not influence TSA levels. Compared with seropositive controls, the concentration of TSA was higher in cats with FIP (556.7 +/- 268.3 mg/L, P = 0.003), tumors (522.5 +/- 294.4 mg/L, P = 0.028), and inflammation (546.8 +/- 208.3 mg/L, P = 0.018). The discriminating power of TSA for FIP is moderate (area under the ROC curve = 0.65) and the likelihood ratio is higher than 3.0 only at high TSA levels. Consequently, TSA could support a diagnosis of FIP only at extremely high serum concentration (> 800 mg/L) or when the pre-test probability of FIP is high. No correlations were found between the TSA and AGP concentrations in cats with FIP, suggesting that sialylated proteins other than AGP are present. Both the antibody titre and the degree of AGP sialylation were negatively correlated with TSA levels, suggesting that increased TSA may contribute to reduce the burden of FCoVs.

  12. Siglec-15, a member of the sialic acid-binding lectin, is a novel regulator for osteoclast differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Hiruma, Yoshiharu, E-mail: hiruma.yoshiharu.hy@daiichisankyo.co.jp [Biological Research Laboratories, Daiichi Sankyo Co. Ltd., Tokyo 134-8630 (Japan); Hirai, Takehiro [Translational Medicine and Clinical Pharmacology Department, Daiichi Sankyo Co. Ltd., Tokyo 134-8630 (Japan); Tsuda, Eisuke [Biological Research Laboratories, Daiichi Sankyo Co. Ltd., Tokyo 134-8630 (Japan)

    2011-06-10

    Highlights: {yields} Siglec-15 was identified as a gene overexpressed in giant cell tumor. {yields} Siglec-15 mRNA expression increased in association with osteoclast differentiation. {yields} Polyclonal antibody to Siglec-15 inhibited osteoclast differentiation in vitro. -- Abstract: Osteoclasts are tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells derived from monocyte/macrophage-lineage precursors and are critically responsible for bone resorption. In giant cell tumor of bone (GCT), numerous TRAP-positive multinucleated giant cells emerge and severe osteolytic bone destruction occurs, implying that the emerged giant cells are biologically similar to osteoclasts. To identify novel genes involved in osteoclastogenesis, we searched genes whose expression pattern was significantly different in GCT from normal and other bone tumor tissues. By screening a human gene expression database, we identified sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) as one of the genes markedly overexpressed in GCT. The mRNA expression level of Siglec-15 increased in association with osteoclast differentiation in cultures of mouse primary unfractionated bone marrow cells (UBMC), RAW264.7 cells of the mouse macrophage cell line and human osteoclast precursors (OCP). Treatment with polyclonal antibody to mouse Siglec-15 markedly inhibited osteoclast differentiation in primary mouse bone marrow monocyte/macrophage (BMM) cells stimulated with receptor activator of nuclear factor {kappa}B ligand (RANKL) or tumor necrosis factor (TNF)-{alpha}. The antibody also inhibited osteoclast differentiation in cultures of mouse UBMC and RAW264.7 cells stimulated with active vitamin D{sub 3} and RANKL, respectively. Finally, treatment with polyclonal antibody to human Siglec-15 inhibited RANKL-induced TRAP-positive multinuclear cell formation in a human OCP culture. These results suggest that Siglec-15 plays an important role in osteoclast differentiation.

  13. Rapid and simple solid-phase esterification of sialic acid residues for quantitative glycomics by mass spectrometry.

    Science.gov (United States)

    Miura, Yoshiaki; Shinohara, Yasuro; Furukawa, Jun-ichi; Nagahori, Noriko; Nishimura, Shin-Ichiro

    2007-01-01

    A rapid and quantitative method for solid-phase methyl esterification of carboxy groups of various sialylated oligosaccharides has been established. The method employed a triazene derivative, 3-methyl-1-p-tolyltriazene, for facile derivatization of oligosaccharides immobilized onto general solid supports such as Affi-Gel Hz and gold colloidal nanoparticles in a multiwell plate. The workflow protocol was optimized for the solid-phase processing of captured sialylated/unsialylated oligosaccharides separated from crude sample mixtures by chemical ligation. From tryptic and/or PNGase F-digest mixtures of glycoproteins, purification by chemoselective immobilization, esterification and recovery were achieved in the same well of the filter plate within three hours when used in conjunction with "glycoblotting technology" (S.-I. Nishimura, K. Niikura, M. Kurogochi, T. Matsushita, M. Fumoto, H. Hinou, R. Kamitani, H. Nakagawa, K. Deguchi, N. Miura, K. Monde, H. Kondo, High-throughput protein glycomics: Combined use of chemoselective glycoblotting and MALDI-TOF/TOF mass spectrometry: Angew. Chem. 2005, 117, 93-98; Angew. Chem. Int. Ed. 2005, 44, 91-96). The recovered materials were directly applicable to subsequent characterization by mass spectrometric techniques such as MALDI-TOF for large-scale glycomics of both neutral and sialylated oligosaccharides. On-bead/on-gold nanoparticle derivatization of glycans containing sialic acids allowed rapid and quantitative glycoform profiling by MALDI-TOF MS with reflector and positive ion mode. In addition to its simplicity and speed, the method eliminates the use of unfavorable halogenated solvents such as chloroform and dichloromethane or volatile solvents such as diethyl ether and hexane, resulting in a practical and green chemical method for automated robotic adaptation.

  14. Epoetin beta pegol, but not recombinant erythropoietin, retains its hematopoietic effect in vivo in the presence of the sialic acid-metabolizing enzyme sialidase.

    Science.gov (United States)

    Aizawa, Ken; Kawasaki, Ryohei; Tashiro, Yoshihito; Hirata, Michinori; Endo, Koichi; Shimonaka, Yasushi

    2016-08-01

    Erythropoiesis-stimulating agents (ESAs) are widely used for treating chronic kidney disease (CKD)-associated anemia. The biological activity of ESAs is mainly regulated by the number of sialic acid-containing carbohydrates on the erythropoietin (EPO) peptide. Sialidase, a sialic acid-metabolizing enzyme that accumulates in CKD patients, is suspected of contributing to shortening the circulation half-life of ESAs. Epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.), is an EPO integrated with methoxypolyethylene glycol (PEG). It has been suggested that C.E.R.A. may exert a favorable therapeutic effect, even under conditions of elevated sialidase; however, no detailed investigation of the pharmacological profile of C.E.R.A. in the presence of sialidase has been reported. In the present study, we injected C.E.R.A. or EPO pre-incubated with sialidase into rats, and assessed the hematopoietic effect by reticulocyte count. The hematopoietic effect of C.E.R.A., but not EPO, was preserved after sialidase treatment, despite the removal of sialic acid. Proliferation of EPO-dependent leukemia cells (AS-E2) was significantly increased by desialylated C.E.R.A. and EPO compared to non-treated C.E.R.A. or EPO. In conclusion, we show that C.E.R.A. exerts a favorable hematopoietic effect even under conditions of elevated sialidase. Our findings may contribute to a better understanding of CKD and more effective therapeutic approaches based on a patient's profile of anemia.

  15. Anti-bacterial effects of enzymatically-isolated sialic acid from glycomacropeptide in a Helicobacter pylori-infected murine model

    Science.gov (United States)

    Noh, Hye-Ji; Koh, Hong Bum; Kim, Hee-Kyoung; Cho, Hyang Hyun

    2017-01-01

    BACKGROUND/OBJECTIVES Helicobacter pylori (H. pylori) colonization of the stomach mucosa and duodenum is the major cause of acute and chronic gastroduodenal pathology in humans. Efforts to find effective anti-bacterial strategies against H. pylori for the non-antibiotic control of H. pylori infection are urgently required. In this study, we used whey to prepare glycomacropeptide (GMP), from which sialic acid (G-SA) was enzymatically isolated. We investigated the anti-bacterial effects of G-SA against H. pylori in vitro and in an H. pylori-infected murine model. MATERIALS/METHODS The anti-bacterial activity of G-SA was measured in vitro using the macrodilution method, and interleukin-8 (IL-8) production was measured in H. pylori and AGS cell co-cultures by ELISA. For in vivo study, G-SA 5 g/kg body weight (bw)/day and H. pylori were administered to mice three times over one week. After one week, G-SA 5 g/kg bw/day alone was administered every day for one week. Tumor necrosis factor-α (TNF-α), IL-1β, IL-6, and IL-10 levels were measured by ELISA to determine the anti-inflammatory effects of G-SA. In addition, real-time PCR was performed to measure the genetic expression of cytotoxin-associated gene A (cagA). RESULTS G-SA inhibited the growth of H. pylori and suppressed IL-8 production in H. pylori and in AGS cell co-cultures in vitro. In the in vivo assay, administration of G-SA reduced levels of IL-1β and IL-6 pro-inflammatory cytokines whereas IL-10 level increased. Also, G-SA suppressed the expression of cagA in the stomach of H. pylori-infected mice. CONCLUSION G-SA possesses anti-H. pylori activity as well as an anti-H. pylori-induced gastric inflammatory effect in an experimental H. pylori-infected murine model. G-SA has potential as an alternative to antibiotics for the prevention of H. pylori infection and H. pylori-induced gastric disease prevention. PMID:28194260

  16. Lysosomal pH Decrease in Inflammatory Cells Used To Enable Activatable Imaging of Inflammation with a Sialic Acid Conjugated Profluorophore.

    Science.gov (United States)

    Yu, Mingzhu; Wu, Xuanjun; Lin, Bijuan; Han, Jiahuai; Yang, Liu; Han, Shoufa

    2015-07-07

    Inflammation causes significant morbidity and mortality, necessitating effective in vivo imaging of inflammation. Prior approaches often rely on combination of optical agents with entities specific for proteinaceous biomarkers overexpressed in inflammatory tissues. We herein report a fundamentally new approach to image inflammation by targeting lysosomes undergoing acidification in inflammatory cells with a sialic acid (Sia) conjugated near-infrared profluorophore (pNIR). Sia-pNIR contains a sialic acid domain for in vivo targeting of inflamed tissues and a pNIR domain which isomerizes into fluorescent and optoacoustic species in acidic lysosomes. Sia-pNIR displays high inflammation-to-healthy tissue signal contrasts in mice treated with Escherichia coli, Staphylococcus aureus, or lipopolysaccharide. In addition, inflammation-associated fluorescence is switched off upon antibiotics treatment in mice. This report shows the potentials of Sia-pNIR for activatable dual-modality inflammation imaging, and particularly the use of lysosomes of inflamed cells as a previously unappreciated biomarker for inflammation imaging.

  17. Molecular dynamics of sialic acid analogues complex with cholera toxin and DFT optimization of ethylene glycol-mediated zinc nanocluster conjugation.

    Science.gov (United States)

    Sharmila, D Jeya Sundara; Jino Blessy, J

    2017-01-01

    Cholera is an infectious disease caused by cholera toxin (CT) protein of bacterium Vibrio cholerae. A sequence of sialic acid (N-acetylneuraminic acid, NeuNAc or Neu5Ac) analogues modified in its C-5 position is modelled using molecular modelling techniques and docked against the CT followed by molecular dynamics simulations. Docking results suggest better binding affinity of NeuNAc analogue towards the binding site of CT. The NeuNAc analogues interact with the active site residues GLU:11, TYR:12, HIS:13, GLY:33, LYS:34, GLU:51, GLN:56, HIE:57, ILE:58, GLN:61, TRP:88, ASN:90 and LYS:91 through intermolecular hydrogen bonding. Analogues N-glycolyl-NeuNAc, N-Pentanoyl-NeuNAc and N-Propanoyl-NeuNAc show the least XPGscore (docking score) of -9.90, -9.16, and -8.91, respectively, and glide energy of -45.99, -42.14 and -41.66 kcal/mol, respectively. Stable nature of CT-N-glycolyl-NeuNAc, CT-N-Pentanoyl-NeuNAc and CT-N-Propanoyl-NeuNAc complexes was verified through molecular dynamics simulations, each for 40 ns using the software Desmond. All the nine NeuNAc analogues show better score for drug-like properties, so could be considered as suitable candidates for drug development for cholera infection. To improve the enhanced binding mode of NeuNAc analogues towards CT, the nine NeuNAc analogues are conjugated with Zn nanoclusters through ethylene glycol (EG) as carriers. The NeuNAc analogues conjugated with EG-Zn nanoclusters show better binding energy towards CT than the unconjugated nine NeuNAc analogues. The electronic structural optimization of EG-Zn nanoclusters was carried out for optimizing their performance as better delivery vehicles for NeuNAc analogues through density functional theory calculations. These sialic acid analogues may be considered as novel leads for the design of drug against cholera and the EG-Zn nanocluster may be a suitable carrier for sialic acid analogues.

  18. Host-mediated selection of influenza virus receptor variants. Sialic acid-alpha 2,6Gal-specific clones of A/duck/Ukraine/1/63 revert to sialic acid-alpha 2,3Gal-specific wild type in ovo.

    Science.gov (United States)

    Rogers, G N; Daniels, R S; Skehel, J J; Wiley, D C; Wang, X F; Higa, H H; Paulson, J C

    1985-06-25

    Human and animal influenza A isolates of the H3 serotype preferentially bind SA alpha 2,6Gal or SA alpha 2,3Gal linkages (where SA represents sialic acid), respectively, on cell-surface sialyloligosaccharides. Previously, we have demonstrated selection of SA alpha 2,3Gal-specific receptor variants of several human viruses which differed from the parent viruses by a single amino acid at residue 226 of the hemagglutinin which is located in the receptor binding pocket (Rogers, G. N., Paulson, J.C., Daniels, R.S., Skehel, J.J., Wilson, I.A., and Wiley, D.C. (1983) Nature 304, 76-78). In this report, the selection in the reverse direction was accomplished starting with a SA alpha 2,3Gal-specific avian virus, A/duck/Ukraine/1/63 (H3N7), yielding SA alpha 2,6Gal-specific variants that exhibit the receptor binding properties characteristic of the human isolates. Selection was again mediated at residue 226 of the hemagglutinin, in this case changing from Gln in the parent virus to Leu in the variants. Although the SA alpha 2,6Gal-specific avian virus variants were stable to passage in MDCK cells, they exhibited dramatic reversion to the SA alpha 2,3Gal-specific phenotype of the parent virus during a single passage in chicken embryos. This was in contrast to the SA alpha 2,6Gal-specific human virus isolates which were stable to passage in both hosts. The reversion of the avian virus variants in eggs provides compelling evidence for host-mediated selection of influenza virus receptor variants.

  19. Anti-HIV Ⅰ/Ⅱ Activity and Molecular Cloning of a Novel Mannose/Sialic Acid-binding Lectin from Rhizome of Polygonatum cyrtonema Hua

    Institute of Scientific and Technical Information of China (English)

    Jie AN; Jin-Ku BAO; Jin-Zhi LIU; Chuan-Fang WU; Jian LI; Lei DAI; Els Van DAMME; Jan BALZARINI; Erik De CLERCQ; Fang CHEN

    2006-01-01

    The anti-human immunodeficiency virus (HIV) Ⅰ/Ⅱ activity of a mannose and sialic acid binding lectin isolated from rhizomes of Polygonatum cyrtonema Hua was elucidated by comparing its HIV infection inhibitory activity in MT-4 and CEM cells with that of other mannose-binding lectins (MBLs). The anti-HIV activity of Polygonatum cyrtonema Hua lectin (PCL) was 10- to 100-fold more potent than other tested MBLs, but without significant cytotoxicity towards MT-4 or CEM cells. To amplify cDNA of PCL by 3'/5'-rapid amplification of cDNA ends (RACE), the 30 amino acids of N-terminal were determined by sequencing and the degenerate oligonucleotide primers were designed. The full-length cDNA of PCL contained 693 bp with an open reading frame encoding a precursor protein of 160 amino acid residues, consisting of a 28-residue signal peptide, a 22-residue C-terminal cleavage peptide and a 110-residue mature polypeptide which contained three tandemly arranged subdomains with an obvious sequence homology to the monocot MBL. However, only one active mannose-binding site (QDNVY) was found in subdomain Ⅰ of PCL, that of subdomain Ⅱ and Ⅲ changed to HNNVY and PDNVY, respectively. There was no intron in PCL, which was in good agreement with other monocot MBLs. Molecular modeling of PCL indicated that its three-dimen-sional structure resembles that of the snowdrop agglutinin. By docking, an active sialic acid-binding site was found in PCL. The instabilization of translation initiation region (TIR) in mRNA of PCL benefits its high expression in rhizomes.

  20. Cytidine-5'-monophosphate-N-acetylneuraminic acid. Asialoglycoprotein sialic acid transferase activity in liver and serum of patients with juvenile hepatic cirrhosis and alpha-1-antitrypsin deficiency.

    Science.gov (United States)

    Kuhlenschmidt, M S; Peters, S P; Pinkard, O D; Glew, R H; Sharp, H

    1976-04-08

    The molecular basis for the accumulation of a substance which displays the immunological reactivity of alpha-1-antitrypsin within vesicles of liver parenchymal cells of individuals with hepatic cirrhosis and serum alpha-1-antitrypsin deficiency remains unclear. We recently reported that serum from a patient with alpha-1-antitrypsin deficiency and hepatic cirrhosis was substantially deficient in sialyltransferease (EC 2.4.99.1) an enzyme which transfers sialic acid from cytidine 5'-monophosphate-N-acetylneuraminic acid to a variety of asialoglycoprotein acceptors. In the present report we have extended these studies to include serum from five additional patients with alpha-1-antitrypsin deficiency and juvenile hepatic cirrhosis as well as a liver specimen obtained at autopsy of one of these patients. We find the sialytransferase activity in serum from six patients with alpha-1-antitrypsin deficiency and hepatic cirrhosis to be 50% of healthy pediatric control values and 30% of pediatric patients with liver disease. However, serum from family members homozygous for alpha-1-antitrypsin deficiency but without hepatic cirrhosis, and serum from patients with a variety of other kinds of liver disease, failed to exhibit the marked sialytransferase deficiency. Similar assays carried out on a homogenate of a liver sample from one patient with alpha-1-antitrypsin deficiency and hepatic cirrhosis indicated that the deficiency of sialyltransferase activity was not demonstrable in liver. Furthermore, a comparative kinetic analysis of serum and liver sialytransferase in normal and afflicted individuals failed to detect differences in substrate affinities which might account for a decrease in functional sialyltransferase capacity in individuals with alpha-1-antitrypsin deficiency and hepatic cirrhosis. These observations suggest that the serum sialyltransferase deficiency in such patients probably arises after chronic and extensive liver disease involving hepatic accumulation of

  1. Sialic acid receptor detection in the human respiratory tract: evidence for widespread distribution of potential binding sites for human and avian influenza viruses

    Directory of Open Access Journals (Sweden)

    Guan Yi

    2007-10-01

    Full Text Available Abstract Background Influenza virus binds to cell receptors via sialic acid (SA linked glycoproteins. They recognize SA on host cells through their haemagglutinins (H. The distribution of SA on cell surfaces is one determinant of host tropism and understanding its expression on human cells and tissues is important for understanding influenza pathogenesis. The objective of this study therefore was to optimize the detection of α2,3-linked and α2,6-linked SA by lectin histochemistry by investigating the binding of Sambucus nigra agglutinin (SNA for SAα2,6Gal and Maackia amurensis agglutinin (MAA for SAα2,3Gal in the respiratory tract of normal adults and children. Methods We used fluorescent and biotinylated SNA and MAA from different suppliers on archived and prospectively collected biopsy and autopsy specimens from the nasopharynx, trachea, bronchus and lungs of fetuses, infants and adults. We compared different methods of unmasking for tissue sections to determine if these would affect lectin binding. Using serial sections we then compared the lectin binding of MAA from different suppliers. Results We found that unmasking using microwave treatment in citrate buffer produced increased lectin binding to the ciliated and glandular epithelium of the respiratory tract. In addition we found that there were differences in tissue distribution of the α2,3 linked SA when 2 different isoforms of MAA (MAA1 and MAA2 lectin were used. MAA1 had widespread binding throughout the upper and lower respiratory tract and showed more binding to the respiratory epithelium of children than in adults. By comparison, MAA2 binding was mainly restricted to the alveolar epithelial cells of the lung with weak binding to goblet cells. SNA binding was detected in bronchial and alveolar epithelial cells and binding of this lectin was stronger to the paediatric epithelium compared to adult epithelium. Furthermore, the MAA lectins from 2 suppliers (Roche and EY Labs tended

  2. Synthesis of screening substrates for the directed evolution of sialic acid aldolase: towards tailored enzymes for the preparation of influenza A sialidase inhibitor analogues.

    Science.gov (United States)

    Woodhall, Thomas; Williams, Gavin; Berry, Alan; Nelson, Adam

    2005-05-01

    The stereoselective synthesis of two epimeric screening substrates, (4R, 5R, 6R)- and (4S, 5R, 6R)-6-dipropylcarbamoyl-2-oxo-4,5,6-trihydroxy-hexanoic acid, for the directed evolution of sialic acid aldolase is described. The complementary methods relied on stereoselective indium-mediated additions of ethyl alpha-bromomethyl acrylate to functionalised aldehydes. With an alpha-hydroxy aldehyde, (2R, 3R)-2,3-dihydroxy-4-oxo butanoic acid dipropylamide, the addition was chelation controlled, and the syn product, (6R, 5R, 4S)-6-dipropylcarbamoyl-2-methylidene-4,5,6-trihydroxy-hexanoic acid ethyl ester, was obtained. In contrast, the stereochemical outcome of the addition to (2R, 3R)-N,N-dipropyl-2,3-O-isopropylidene-4-oxobutyramide was consistent with Felkin-Anh control, and the anti adduct, (4R, 5R, 6R)-6-dipropylcarbamoyl-2-methylidene-4-hydroxy-5,6-O-isopropylidene-hexanoic acid ethyl ester, was the major product. Ozonolysis and deprotection gave the screening substrates as mixtures of furanose and pyranose forms, in good yields.

  3. Loss of sialic acid binding domain redirects protein σ1 to enhance M cell-directed vaccination.

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    Dagmara Zlotkowska

    Full Text Available Ovalbumin (OVA genetically fused to protein sigma 1 (pσ1 results in tolerance to both OVA and pσ1. Pσ1 binds in a multi-step fashion, involving both protein- and carbohydrate-based receptors. To assess the relative pσ1 components responsible for inducing tolerance and the importance of its sialic binding domain (SABD for immunization, modified OVA-pσ1, termed OVA-pσ1(short, was deleted of its SABD, but with its M cell targeting moiety intact, and was found to be immunostimulatory and enhanced CD4(+ and CD8(+ T cell proliferation. When used to nasally immunize mice given with and without cholera toxin (CT adjuvant, elevated SIgA and serum IgG responses were induced, and OVA-pσ1(s was more efficient for immunization than native OVA+CT. The immune antibodies (Abs were derived from elevated Ab-forming cells in the upper respiratory tissues and submaxillary glands and were supported by mixed Th cell responses. Thus, these studies show that pσ1(s can be fused to vaccines to effectively elicit improved SIgA responses.

  4. Sialic Acid-Binding Immunoglobulin-like Lectin G Promotes Atherosclerosis and Liver Inflammation by Suppressing the Protective Functions of B-1 Cells

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    Sabrina Gruber

    2016-03-01

    Full Text Available Atherosclerosis is initiated and sustained by hypercholesterolemia, which results in the generation of oxidized LDL (OxLDL and other metabolic byproducts that trigger inflammation. Specific immune responses have been shown to modulate the inflammatory response during atherogenesis. The sialic acid-binding immunoglobulin-like lectin G (Siglec-G is a negative regulator of the functions of several immune cells, including myeloid cells and B-1 cells. Here, we show that deficiency of Siglec-G in atherosclerosis-prone mice inhibits plaque formation and diet-induced hepatic inflammation. We further demonstrate that selective deficiency of Siglec-G in B cells alone is sufficient to mediate these effects. Levels of B-1 cell-derived natural IgM with specificity for OxLDL were significantly increased in the plasma and peritoneal cavity of Siglec-G-deficient mice. Consistent with the neutralizing functions of OxLDL-specific IgM, Siglec-G-deficient mice were protected from OxLDL-induced sterile inflammation. Thus, Siglec-G promotes atherosclerosis and hepatic inflammation by suppressing protective anti-inflammatory effector functions of B cells.

  5. Association between dental-oral health in young adults and salivary glutathione, lipid peroxidation and sialic acid levels and carbonic anhydrase activity

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    L.K. Öztürk

    2008-11-01

    Full Text Available The aim of the present study was to evaluate the relationship between salivary oxidative stress and dental-oral health. Healthy young adults, matched for gender and age, with (N = 21, 10 men, mean age: 20.3 ± 1 years and without (N = 16, 8 men, mean age: 21.2 ± 1.8 years caries were included in this study. The World Health Organization (WHO caries diagnostic criteria were used for determining the decayed, missing, filled teeth (DMFT index. The oral hygiene and gingival status were assessed using the simplified oral hygiene index and gingival index, respectively. Unstimulated salivary total protein, glutathione (GSH, lipid peroxidation and total sialic acid levels, carbonic anhydrase activity, and salivary buffering capacity were determined by standard methods. Furthermore, salivary pH was measured with pH paper and salivary flow rate was calculated. Simplified oral hygiene index and gingival index were not significantly different between groups but DMFT scores were significant (P < 0.01. Only, GSH values were significantly different (P < 0.05 between groups (2.2 and 1.6 mg/g protein in young adults without caries and with caries, respectively. There was a significant negative correlation between DMFT and GSH (r = -0.391; P < 0.05; Pearson's correlation coefficient. Our results suggest that there is an association between caries history and salivary GSH levels.

  6. Pretreatment of Sialic Acid Efficiently Prevents Lipopolysaccharide-Induced Acute Renal Failure and Suppresses TLR4/gp91-Mediated Apoptotic Signaling

    Directory of Open Access Journals (Sweden)

    Shih-Ping Hsu

    2016-05-01

    Full Text Available Background/Aims: Lipopolysaccharides (LPS binding to Toll-like receptor 4 (TLR4 activate NADPH oxidase gp91 subunit-mediated inflammation and oxidative damage. Recognizing the high binding affinity of sialic acid (SA with LPS, we further explored the preventive potential of SA pretreatment on LPS-evoked acute renal failure (ARF. Methods: We determined the effect of intravenous SA 30 min before LPS-induced injury in urethane-anesthetized female Wistar rats by evaluating kidney reactive oxygen species (ROS responses, renal and systemic hemodynamics, renal function, histopathology, and molecular mechanisms. Results: LPS time-dependently reduced arterial blood pressure, renal microcirculation, and increased blood urea nitrogen and creatinine in the rats. LPS enhanced monocyte/macrophage infiltration and ROS production, and subsequently impaired kidneys with the enhancement of TLR4/NADPH oxidase gp91/Caspase 3/poly-(ADP-ribose-polymerase (PARP-mediated apoptosis in the kidneys. SA pretreatment effectively alleviated LPS-induced ARF. The levels of LPS-increased ED-1 infiltration and ROS production in the kidney were significantly depressed by SA pretreatment. Furthermore, SA pretreatment significantly depressed TLR4 activation, gp91 expression, and Caspase 3/PARP induced apoptosis in the kidneys. Conclusion: We suggest that pretreatment of SA significantly and preventively attenuated LPS-induced detrimental effects on systemic and renal hemodynamics, renal ROS production and renal function, as well as, LPS-activated TLR4/gp91/Caspase3 mediated apoptosis signaling.

  7. [Change in acylneuraminic acid content of T-lymphocytes and in plasma in breast cancer].

    Science.gov (United States)

    Stickl, H; Huber, W; Faillard, H; Becker, A; Holzhauser, R; Graeff, H

    1991-01-04

    Increased sialic acid levels reflecting tumor burden are found on the surface of T-lymphocytes and in the plasma of patients with carcinoma of the mammary gland. The data of the determinations of sialic acid content and distribution on T-cells, using microanalytical methods such as HPLC and a colorimetric test, show that the total sialic acid content is increased by about 60% and that nearly 80-90% of the sialic acids consist of N-acetyl-9-O-acetyl-neuraminic acid, in comparison to the healthy controls (not containing O-acetylated neuraminic acid). Investigations on lymphocytes of malignant melanoma patients show similar changes of sialic acid content and distribution on the cell surface. Increased sialic acid levels are also found in the plasma of patients with cancer but no O-acetylated derivative can be found. Furthermore the examinations show that the separation of the T-lymphocytes from the total lymphocyte fraction is not required. Determination of sialic acids in the total lymphocyte fraction can be a simplification in carrying out further diagnostic investigations. A high level of sialic acids as "antirecognition factor" seems to be not only a marker of tumor cells but also an attribute of T-lymphocytes, involved in the defence against the malignoma (malignant melanoma, breast cancer). Considering the possible contribution of sialic acid to the immunoregulatory protective mechanism during the first stage of pregnancy, sialic acid content and distribution on T-cells of pregnant women are investigated. Both an increase and a change in the distribution of sialic acids can be excluded.

  8. The random co-polymer glatiramer acetate rapidly kills primary human leukocytes through sialic-acid-dependent cell membrane damage

    DEFF Research Database (Denmark)

    Christiansen, Stig Hill; Zhang, Xianwei; Juul-Madsen, Kristian;

    2017-01-01

    The formulation glatiramer acetate (GA) is widely used in therapy of multiple sclerosis. GA consists of random copolymers of four amino acids, in ratios that produce a predominantly positive charge and an amphipathic character. With the extraordinary complexity of the drug, several pharmacological...

  9. High-resolution 1H-NMR spectroscopy of free and glycosidically linked O-acetylated sialic acids

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Haverkamp, J.; Halbeek, H. van; Dorland, L.; Pfeil, R.; Schauer, R.

    1982-01-01

    A number of naturally occurring and synthetic, partially O-acetylated derivatives of N-acetylneuraminic and N-glycoloylneuraminic acids have been investigated by 360-MHz 1H-NMR spectroscopy. O-Acetylation causes strong downfield shifts for the resonances of neighbouring sugar-skeleton protons. The c

  10. Relationship between proliferative activity of bone marrow micrometastasis and plasmatic level of a new cancer marker: lipid associated sialic acid (LASA) in human breast cancer.

    Science.gov (United States)

    Ginsbourg, M; Musset, M; Misset, J L; Mathé, G

    1986-01-01

    The correlation between elevated level of a new plasma cancer marker, Lipid Associated Sialic Acid (LASA) and detection of bone marrow heterotopic epithelial cells by monoclonal antibodies using an immunocytologic technique, associated with the study of the proliferative activity of these heterotopic cells by measurement of their labelling index (LI) was analyzed in 158 samples obtained from 94 breast cancer patients. Six different groups of patients in complete remission of breast cancer, after radical treatment of the primary (minimal residual disease (MRD] were defined, according to the presence with or without proliferative activity of heterotopic cells in the bone marrow or the absence of such cells and to the level, normal or elevated of LASA in the serum of the same patient at the same time. 115 samples (73%) of the patients had an elevated LASA level at the time of the study among which 71 (45%) came from patients in which heterotopic cells were detected in the bone marrow, 32 (20%) of which with proliferative activity (LI+) 39 (25%) without (LI-). In 44 (28%) samples, no heterotopic cells were detected in the B.M. 43 samples (27%) of the patients had a normal LASA level. In 29 (18%) no heterotopic cells could be detected in the B.M. In only 14 could such cells be found, 5 with LI+, 9 with LI-. Both of these cytological and biological parameters can be useful markers of minimal residual disease and help to determine the prognosis and define optimal therapeutic strategy for curable breast cancer. Their prognostic value in predicting relapse awaits further observation with longer follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Secreted Ectodomain of Sialic Acid-Binding Ig-Like Lectin-9 and Monocyte Chemoattractant Protein-1 Synergistically Regenerate Transected Rat Peripheral Nerves by Altering Macrophage Polarity.

    Science.gov (United States)

    Kano, Fumiya; Matsubara, Kohki; Ueda, Minoru; Hibi, Hideharu; Yamamoto, Akihito

    2017-03-01

    Peripheral nerves (PNs) exhibit remarkable self-repairing reparative activity after a simple crush or cut injury. However, the neuronal transection involving a nerve gap overwhelms their repairing activity and causes persistent paralysis. Here, we show that an implantation of the serum-free conditioned medium from stem cells from human exfoliated deciduous teeth (SHED-CM) immersed in a collagen sponge into the nerve gap formed by rat facial nerves transection restored the neurological function. In contrast, SHED-CM specifically depleted of a set of anti-inflammatory M2 macrophage inducers, monocyte chemoattractant protein-1 (MCP-1) and the secreted ectodomain of sialic acid-binding Ig-like lectin-9 (sSiglec-9) lost the ability to restore neurological function in this model. Notably, the combination of MCP-1 and sSiglec-9 induced the polarization of M2 macrophages in vitro, resulting in the expression of multiple trophic factors that enhanced proliferation, migration, and differentiation of Schwann cells, blood vessel formation, and nerve fiber extension. Furthermore, the implantation of a collagen graft containing MCP-1/sSiglec-9 into the nerve gap induced anti-inflammatory M2 macrophage polarization, generated a Schwann-cell bridge instead of fibrotic scar, induced axonal regrowth, and restored nerve function. The specific elimination of M2 macrophages by Mannosylated-Clodrosome suppressed the MCP-1/sSiglec-9-mediated neurological recovery. Taken together, our data suggest that MCP-1/sSiglec-9 regenerates PNs by inducing tissue-repairing M2 macrophages and may provide therapeutic benefits for severe peripheral nerve injuries. Stem Cells 2017;35:641-653.

  12. Sialic acid, ferritin and CEA levels in peripheral blood and blood draining from the tumor in breast cancer.

    Science.gov (United States)

    Monti, M; Catania, S; Locatelli, E; Scazzoso, A; Calzaferri, G; Cunietti, E

    1988-01-01

    Concentrations of total serum N-acetyl-neuraminic acid, carcinoembryonic antigen, ferritin, lactate dehydrogenase, creatine phosphokinase and total proteins were measured in both tumor drainage blood (axillary vein) and in peripheral blood taken during surgery from 44 breast cancer patients. There were no significant differences in any of the markers between mean values in peripheral and tumor drainage blood, between cancer patients and healthy controls, between patients with or without axillary lymph node metastases, or according to the site of breast mass.

  13. The random co-polymer glatiramer acetate rapidly kills primary human leukocytes through sialic-acid-dependent cell membrane damage

    DEFF Research Database (Denmark)

    Christiansen, Stig Hill; Zhang, Xianwei; Juul-Madsen, Kristian;

    2017-01-01

    The formulation glatiramer acetate (GA) is widely used in therapy of multiple sclerosis. GA consists of random copolymers of four amino acids, in ratios that produce a predominantly positive charge and an amphipathic character. With the extraordinary complexity of the drug, several pharmacological...... contacts, which is critical for the lytic properties. In our study, SAXS showed that GA also forms this type of contacts. Taken together, our study offers new insight on the immunomodulatory mode-of-action of positively charged co-polymers. The comparison of LL-37 and GA highlights a consistent requirement...

  14. Exogenous incorporation of neugc-rich mucin augments n-glycolyl sialic acid content and promotes malignant phenotype in mouse tumor cell lines

    Directory of Open Access Journals (Sweden)

    Alonso Daniel F

    2009-12-01

    Full Text Available Abstract Background Carbohydrates embedded in the plasma membrane are one of the main actors involved in the communication of cells with the microenvironment. Neuraminic sialic acids are glycocalyx sugars that play important roles in the modulation of malignant cell behaviour. N-glycolylneuraminic acid (NeuGc is synthesized by the cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH, an enzyme expressed in all mammals except humans. In mice, this sugar is synthesized in several somatic tissues. Methods We used the B16 melanoma and F3II mammary carcinoma mouse tumor cell lines. By CMAH directed RT-PCR and NeuGc detection with the specific anti-NeuGc-GM3 antibody 14F7 we evaluated enzyme and ganglioside expression in tumor cells, respectively. Expression of NeuGc-GM3 ganglioside was reached by in vitro incubation with NeuGc-rich bovine submaxillary mucin and evaluated by slot-blot and immunohistochemistry assays using the 14F7 antibody. Tumor cells treated with mucin or purified NeuGc were injected s.c. and i.v. in syngeneic mice to evaluate tumor and metastatic growth. Results In the present work we demonstrated the absence of expression of CMAH enzyme in B16 melanoma and F3II mammary carcinoma cells. In vitro incubation of these NeuGc-negative cells with NeuGc-rich mucin increased the presence of NeuGc in cell membranes for at least 48-72 h, as a component of the GM3 ganglioside. Preincubation with NeuGc-rich mucin reduced tumor latency and increased the metastatic potential of tumor cells in syngeneic animals. Similar results were obtained when cells were incubated with purified NeuGc alone. Conclusion Our results indicate that B16 and F3II mouse tumor cell lines do not express NeuGc in cell membranes but they are able to incorporate NeuGc from an exogenous source, contributing to the malignant phenotype of melanoma and mammary carcinoma cells.

  15. Crystal structures of the staphylococcal toxin SSL5 in complex with sialyl Lewis X reveal a conserved binding site that shares common features with viral and bacterial sialic acid binding proteins.

    Science.gov (United States)

    Baker, Heather M; Basu, Indira; Chung, Matthew C; Caradoc-Davies, Tom; Fraser, John D; Baker, Edward N

    2007-12-14

    Staphylococcus aureus is a significant human pathogen. Among its large repertoire of secreted toxins is a group of staphylococcal superantigen-like proteins (SSLs). These are homologous to superantigens but do not have the same activity. SSL5 is shown here to bind to human granulocytes and to the cell surface receptors for human IgA (Fc alphaRI) and P-selectin [P-selectin glycoprotein ligand-1 (PSGL-1)] in a sialic acid (Sia)-dependent manner. Co-crystallization of SSL5 with the tetrasaccharide sialyl Lewis X (sLe(X)), a key determinant of PSGL-1 binding to P-selectin, led to crystal structures of the SSL5-sLe(X) complex at resolutions of 1.65 and 2.75 A for crystals at two pH values. In both structures, sLe(X) bound to a specific site on the surface of the C-terminal domain of SSL5 in a conformation identical with that bound by P-selectin. Conservation of the key carbohydrate binding residues indicates that this ability to bind human glycans is shared by a substantial subgroup of the SSLs, including SSL2, SSL3, SSL4, SSL5, SSL6, and SSL11. This indicates that the ability to target human glycans is an important property of this group of toxins. Structural comparisons also showed that the Sia binding site in SSL5 contains a substructure that is shared by other Sia binding proteins from bacteria as well as viruses and represents a common binding motif.

  16. Crystal Structures of the Staphylococcal Toxin SSL5 in Complex With Sialyl-Lewis X Reveal a Conserved Binding Site That Shares Common Features With Viral And Bacterial Sialic Acid-Binding Proteins

    Energy Technology Data Exchange (ETDEWEB)

    Baker, H.M.; Basu, I.; Chung, M.C.; Caradoc-Davies, T.; Fraser, J.D.; Baker, E.N.

    2009-06-02

    Staphylococcus aureus is a significant human pathogen. Among its large repertoire of secreted toxins is a group of staphylococcal superantigen-like proteins (SSLs). These are homologous to superantigens but do not have the same activity. SSL5 is shown here to bind to human granulocytes and to the cell surface receptors for human IgA (Fc alphaRI) and P-selectin [P-selectin glycoprotein ligand-1 (PSGL-1)] in a sialic acid (Sia)-dependent manner. Co-crystallization of SSL5 with the tetrasaccharide sialyl Lewis X (sLe(X)), a key determinant of PSGL-1 binding to P-selectin, led to crystal structures of the SSL5-sLe(X) complex at resolutions of 1.65 and 2.75 A for crystals at two pH values. In both structures, sLe(X) bound to a specific site on the surface of the C-terminal domain of SSL5 in a conformation identical with that bound by P-selectin. Conservation of the key carbohydrate binding residues indicates that this ability to bind human glycans is shared by a substantial subgroup of the SSLs, including SSL2, SSL3, SSL4, SSL5, SSL6, and SSL11. This indicates that the ability to target human glycans is an important property of this group of toxins. Structural comparisons also showed that the Sia binding site in SSL5 contains a substructure that is shared by other Sia binding proteins from bacteria as well as viruses and represents a common binding motif.

  17. Human risk of diseases associated with red meat intake: Analysis of current theories and proposed role for metabolic incorporation of a non-human sialic acid.

    Science.gov (United States)

    Alisson-Silva, Frederico; Kawanishi, Kunio; Varki, Ajit

    2016-10-01

    -human sialic acid N-glycolylneuraminic acid (Neu5Gc) into the tissues of red meat consumers and the subsequent interaction with inflammation-provoking antibodies against this "xenoautoantigen". Overall, we conclude that while multiple mechanisms are likely operative, many proposed theories to date are not specific for red meat, and that the viral and xenoautoantigen theories deserve further consideration. Importantly, there are potential non-toxic dietary antidotes, if the xenoautoantigen theory is indeed correct. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. An O-glycoside of Sialic Acid Derivative that inhibits Both Hemagglutinin and Sialidase Activities of Influenza Viruses

    Institute of Scientific and Technical Information of China (English)

    GuoChao-Tan; SunXue-Long; Osamukanie; KennedyFrancisShortridge; TakashiSuzuki; KazuyaI.-P.JwaHidari; Chi-HueyWong; YasuoSuzuki

    2005-01-01

    The compound Neu5Ac3αF-DSPE (4), in which the C-3 position was modified with an axial fluorine atom, inhibited the catalytic hydrolysis of influenza virus sialidase and the binding activity of hemagglutinin. The inhibitory activities to sialidases were independent of virus isolates examined.With the positive results obtained for inhibition of hemagglutination and hemolysis induced by A/Aichi/2/68 virus,the inhibitory effect of Neu5Ac3αFDSPE (4) against MDCK cells was examined, and it was found that 4 inhibits the viral infection with IC50 value of 5.6 μM based on the cytopathic effects. The experimental results indicate that compound 4 not only inhibits the attachment of virus to the cell surface receptor but also disturbs the release of the progeny viruses from infected cells by inhibiting both hemagglutinin and sialidase of the influenza viruses.The study suggested that the compound is a new class of bifunctional drug candidates for the future chemotherapy of influenza.

  19. RNase activity of sialic acid-binding lectin from bullfrog eggs drives antitumor effect via the activation of p38 MAPK to caspase-3/7 signaling pathway in human breast cancer cells

    OpenAIRE

    Kariya, Yukiko; Tatsuta, Takeo; Sugawara, Shigeki; Kariya, Yoshinobu; Nitta, Kazuo; Hosono, Masahiro

    2016-01-01

    Sialic acid-binding lectin obtained from bullfrog eggs (SBL) induces cell death in cancer cells but not in normal cells. This antitumor effect is mediated through its ribo-nuclease (RNase) activity. However, the underlying molecular mechanisms remain unclear. We found that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was activated when SBL induced cell death in three human breast cancer cell lines: SK-BR-3, MCF-7, and MDA-MB231. The suppression of p38 MAPK phosphorylation...

  20. Ácidos siálicos: da compreensão do seu envolvimento em processos biológicos ao desenvolvimento de fármacos contra o agente etiológico da gripe Sialic acids: from the comprehension of their involvement in biological processes to antiinfluenza drug design

    Directory of Open Access Journals (Sweden)

    Ângelo de Fátima

    2005-03-01

    Full Text Available Sialic acids are nine-carbon carbohydrates that occur widely in nature and occupy the terminal portions of some glycoproteins and glycolipids of cell membranes. These carbohydrates are closely involved in cell-cell interactions and in processes such as microbial infection, inflammation, etc. Studies on the participation of sialic acids in biological processes have provided comprehension about their role in the infection by the influenza virus, the causal agent of flu. In this article, we present an overview of the importance of sialic acids in the influenza virus infection and how the knowledge of their involvement in this process has allowed the development of selective and efficient drugs against the virus.

  1. 血清唾液酸水平检测在非小细胞肺癌中的诊断价值%Estimation of serum total sialic acid levels as tumor markers in non-small cell lung cancer

    Institute of Scientific and Technical Information of China (English)

    王萍; 王立伟; 张铁; 赵兴波; 张远春

    2012-01-01

    目的 评估血清唾液酸水平在非小细胞肺癌诊断与疗效监测中的应用价值.方法 采用酶法对60例健康人(健康对照组),30例肺部良性疾病患者(肺部良性疾病组),100例非小细胞肺癌患者(非小细胞肺癌组)进行血清唾液酸含量的统计分析.结果 健康对照组血清唾液酸水平为(568±62) mg/L,肺部良性疾病组和非小细胞肺癌组血清唾液酸水平分别为(639±92) mg/L和(813±218)mg/L,非小细胞肺癌患者血清的唾液酸水平明显高于健康对照组和良性疾病组(P<0.01);根据健康对照组的检测数值,唾液酸检测非小细胞肺癌的Cut-off值为695 mg/L,敏感度为69.00%,特异度为88.90%.100例非小细胞肺癌患者中,腺癌、鳞癌、鳞腺癌和未分化癌各25例.其中腺癌组、鳞癌组、鳞腺癌组和未分化癌组血清唾液酸水平分别为( 845±91) mg/L、(782±91)mg/L、(794±126)mg/L和(831±113) mg/L,不同组织病理类型的恶性肿瘤的血清唾液酸含量明显高于对照组,但各组织病理类型的恶性肿瘤之间的血清唾液酸含量差异无统计学意义(P>0.05).非小细胞肺癌患者血清唾液酸水平随着肿瘤分级、分期的升高而升高.结论 血清中唾液酸检测在非小细胞肺癌的筛查、诊断、术后疗效评估及监测均有重要意义.%Objective Sialic acid has recently been suggested as a marker of non-small cell lung cancer.The purpose of this study was to evaluate the utility of serum sialic acid in diagnosis and early detection of non-small cell lung cancer.Methods We analyzed serum samples that had been collected between 2010 and 2011 from 100 patients with Non-small cell lung cancer of different histopathology types before tumor resection at various stages [stage Ⅰ (n=15),stage Ⅱ (n=25),stage Ⅲ (n =40),and stageⅣ(n =20)]; adenocarcinoma(n =25),squamous cell carcinoma( n =25 ),adenosquamous carcinoma( n =25 ),undifferentiated carcinoma( n =25 ),30 benign lung

  2. Two Types of Antibodies Are Induced by Vaccination with A/California/2009pdm Virus: Binding near the Sialic Acid-Binding Pocket and Neutralizing Both H1N1 and H5N1 Viruses

    Science.gov (United States)

    Ohshima, Nobuko; Kubota-Koketsu, Ritsuko; Iba, Yoshitaka; Okuno, Yoshinobu; Kurosawa, Yoshikazu

    2014-01-01

    Many people have a history of catching the flu several times during childhood but no additional flu in adulthood, even without vaccination. We analyzed the total repertoire of antibodies (Abs) against influenza A group 1 viruses induced in such a flu-resistant person after vaccination with 2009 H1N1 pandemic influenza virus. They were classified into two types, with no exceptions. The first type, the products of B cells newly induced through vaccination, binds near the sialic acid-binding pocket. The second type, the products of long-lived memory B cells established before vaccination, utilizes the 1-69 VH gene, binds to the stem of HA, and neutralizes both H1N1 and H5N1 viruses with few exceptions. These observations indicate that the sialic acid-binding pocket and its surrounding region are immunogenically very potent and majority of the B cells whose growth is newly induced by vaccination produce Abs that recognize these regions. However, they play a role in protection against influenza virus infection for a short period since variant viruses that have acquired resistance to these Abs become dominant. On the other hand, although the stem of HA is immunogenically not potent, the second type of B cells eventually becomes dominant. Thus, a selection system should function in forming the repertoire of long-lived memory B cells and the stability of the epitope would greatly affect the fate of the memory cells. Acquisition of the ability to produce Abs that bind to the stable epitope could be a major factor of flu resistance. PMID:24505283

  3. Two types of antibodies are induced by vaccination with A/California/2009 pdm virus: binding near the sialic acid-binding pocket and neutralizing both H1N1 and H5N1 viruses.

    Directory of Open Access Journals (Sweden)

    Nobuko Ohshima

    Full Text Available Many people have a history of catching the flu several times during childhood but no additional flu in adulthood, even without vaccination. We analyzed the total repertoire of antibodies (Abs against influenza A group 1 viruses induced in such a flu-resistant person after vaccination with 2009 H1N1 pandemic influenza virus. They were classified into two types, with no exceptions. The first type, the products of B cells newly induced through vaccination, binds near the sialic acid-binding pocket. The second type, the products of long-lived memory B cells established before vaccination, utilizes the 1-69 VH gene, binds to the stem of HA, and neutralizes both H1N1 and H5N1 viruses with few exceptions. These observations indicate that the sialic acid-binding pocket and its surrounding region are immunogenically very potent and majority of the B cells whose growth is newly induced by vaccination produce Abs that recognize these regions. However, they play a role in protection against influenza virus infection for a short period since variant viruses that have acquired resistance to these Abs become dominant. On the other hand, although the stem of HA is immunogenically not potent, the second type of B cells eventually becomes dominant. Thus, a selection system should function in forming the repertoire of long-lived memory B cells and the stability of the epitope would greatly affect the fate of the memory cells. Acquisition of the ability to produce Abs that bind to the stable epitope could be a major factor of flu resistance.

  4. The clinical features of serum total sialic acid levels in pathological newborn%病理状态新生儿血清唾液酸水平分析

    Institute of Scientific and Technical Information of China (English)

    阮莉莉; 华春珍; 方妍彤; 王晓安

    2014-01-01

    Objective To investigate the serum sialic acid ( SIA ) levels in pathological newborn and evaluate the correlation between SIA levels and gestational ages or ages .Method Premature newborn and mature newborn were grouped according to gestational ages and not more than 24h subgroup, 25 h~7 d and more than 7d subgroups were defined by day ages .The enzymatic method was used when the contents of serum SIA were detected .The statistical analysis software, SPSS version 17.0 was used in the study.Findings A total of 987 newborn, including 238 (24.1%) pre-term newborns, 737 (75.3%) full term newborns and 6(0.6%)pos-term newborns were included in the study .The serum SIA levels of the ≤24h subgroup, 25 h~7 d subgroup and>7d subgroup in the pre-full newborns group were 27.2 ±8.1mg/dl, 33.3 ±5.8 mg/dl and 32.9 ±6.2 mg/dl respectively,which were significant lower than that in the full term group in which the SIA level were 30.4 ±9.2mg/dl,35.4 ±6.7 mg/dl and 37.6 ±9.0mg/dl instead.Lower SIA level was found in≤24h subgroups compared with the 25 h ~7 d subgroups or >7d subgroups in both pre-term and full term groups . Conclusion There was correlation between serum sialic acid level and day age in newborns in the study .Lower SIA level was identified in pre-full newborn when compared with the full term newborn .%目的:探讨病理状态新生儿血清唾液酸(sialic acids, SIA)水平及其与胎龄和日龄的关系。方法将因病理状态住院的新生儿(987例)分早产儿(238例)和足月儿(743例)两组,每组又根据日龄分24 h以内、25 h~7 d和大于7 d亚组,SIA测定采用神经氨酸苷酶法。结果早产儿各亚组血清SIA水平显著低于足月儿相应亚组( P<0.05);早产儿≤24h亚组血清SIA水平显著低于25 h~7 d亚组(t=4.70,P<0.01);早产儿组和足月儿组中≤24 h亚组血清SIA水平均显著低于25 h~7 d亚组或>7 d亚组。结论本组新生儿血清唾液酸

  5. Influences of paliperidone and clozapine on serum sialic acid levels of chronic schizophrenia%帕利哌酮与氯氮平对慢性精神分裂症血清唾液酸水平的影响

    Institute of Scientific and Technical Information of China (English)

    谭新国; 息培兴

    2016-01-01

    目的:探讨帕利哌酮与氯氮平治疗慢性精神分裂症患者的临床疗效以及对血清唾液酸水平的影响。方法将67例住院男性慢性精神分裂症患者采用抛币法随机分为两组,帕利哌酮组(34例)予以帕利哌酮治疗,氯氮平组(33例)予以氯氮平治疗,观察8周。于治疗前后采用阳性与阴性症状量表、副反应量表评定临床疗效及不良反应,同时检测血清唾液酸水平的变化。结果治疗2周末起两组阳性与阴性症状量表总分及各因子分均治疗前显著降低(P<0.01),治疗各时点两组评分比较差异无显著性( P>0.05);治疗8周末帕利哌酮组总有效率为61.8%,氯氮平组为63.6%,两组比较差异无显著性( P>0.05)。治疗前后帕利哌酮组血清唾液酸水平无显著变化(P>0.05),氯氮平组治疗2周及4周末较治疗前显著升高(P<0.01),且显著高于帕利哌酮组(P<0.01)。治疗8周末帕利哌酮组副反应量表评分显著低于氯氮平组(P<0.01)。结论帕利哌酮与氯氮平治疗慢性精神分裂症疗效显著,总体疗效相当,但帕利哌酮对血清唾液酸水平无明显影响,安全性更高。%Objective To explore the influences of paliperidone and clozapine on the curative effect and se‐rum sialic acid levels of chronic schizophrenia .Methods Sixty‐seventy chronic schizophrenics were ran‐domly divided into two groups according to throwing coin ,paliperidone group (n=34) was treated with paliperidone and clozapine group (n=33) with clozapine for 8 weeks .Curative effects were assessed with the Positive and Negative Syndrome Scale (TESS) before and after treatment and adverse reactions with the Treatment Emergent Symptom Scale (TESS) ,at the same time changes of serum sialic acid levels de‐tected .Results Since the edn of the 2nd week the total and each factor scores of both groups lowered more

  6. 孕妇血清唾液酸与正常新生儿的体格生长%Effects of serum sialic acid in pregnant women on neonatal physical growth

    Institute of Scientific and Technical Information of China (English)

    乔阳; 白增华; 王熲; 金华; 柏丹丹; 马亚萍; 古桂雄

    2013-01-01

    [Objective] To investigate the correlation between the maternal serum sialic acid (SA) contents,umbilical cord serum SA contents,SA placenta transport rate with infant early growth and development.[Methods] Prospective cohort study was carried from early pregnancy,followed up to middle,late pregnancy and delivery.The relationships between maternal serum sialic acid at three stages of pregnancy,with offspring birth weight,height,head circumference and Kaup index were carried out.[Results] There were no significant differences in the neonatal birth weight,birth length,birth head circumference and Kaup index respectively in different serum SA contents in early pregnancy,middle pregnancy and late pregnancy(P>0.05).And there were no significant differences of umbilical cord serum SA and SA placenta transfer rate on neonatal outcome either(P>0.05).[Conclusions] There are no significant effects of maternal serum SA contents during pregnancy,fetal umbilical cord SA levels and SA placenta transfer rate on birth physical growth.SA doesn't cause obesity to infants.SA placenta transport rate can reflect the nutritional needs for fetal growth and development.%[目的]研究孕妇不同妊娠期的血清唾液酸含量、脐血清唾液酸含量、唾液酸胎盘转运率与新生儿体格生长的关系. [方法]采取前瞻性队列研究的方法,从妊早、中、晚期至分娩时,分析孕期血清唾液酸水平与子代出生体重、身长、头围和Kaup指数的关系. [结果]妊早、中、晚期孕妇不同血清唾液酸含量的新生儿出生体重、出生身长、出生头围及Kaup指数差异均无统计学意义(P>0.05);不同脐血清唾液酸和唾液酸胎盘转运率的新生儿出生体格差异亦无统计学意义(P>0.05). [结论]妊娠期的唾液酸含量、新生儿脐唾液酸含量和唾液酸胎盘运转率对新生儿出生体格生长无显著影响,唾液酸不会对婴儿造成肥胖的影响,唾液酸胎盘转运率只是反映

  7. RNase activity of sialic acid-binding lectin from bullfrog eggs drives antitumor effect via the activation of p38 MAPK to caspase-3/7 signaling pathway in human breast cancer cells

    Science.gov (United States)

    Kariya, Yukiko; Tatsuta, Takeo; Sugawara, Shigeki; Kariya, Yoshinobu; Nitta, Kazuo; Hosono, Masahiro

    2016-01-01

    Sialic acid-binding lectin obtained from bullfrog eggs (SBL) induces cell death in cancer cells but not in normal cells. This antitumor effect is mediated through its ribo-nuclease (RNase) activity. However, the underlying molecular mechanisms remain unclear. We found that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was activated when SBL induced cell death in three human breast cancer cell lines: SK-BR-3, MCF-7, and MDA-MB231. The suppression of p38 MAPK phosphorylation by a p38 MAPK inhibitor as well as short interference RNA knockdown of p38 MAPK expression significantly decreased cell death and increased the cell viability of SBL-treated MDA-MB231 cells. H103A, an SBL mutant lacking in RNase activity, showed decreased SBL-induced cell death compared with native SBL. However, the loss of RNase activity of SBL had no effect on its internalization into cells. The H103A mutant also displayed decreased phosphorylation of p38 MAPK. Moreover, SBL promoted caspase-3/7 activation followed by a cleavage of poly (ADP-ribose)-polymerase, whereas the SBL mutant, H103A, lost this ability. The SBL-induced caspase-3/7 activation was suppressed by the p38 MAPK inhibitor, SB203580, as well as pan-caspase inhibitor, zVAD-fmk. In the presence of zVAD-fmk, the SBL-induced cell death was decreased. In addition, the cell viability of SBL-treated MDA-MB231 cells recovered by zVAD-fmk treatment. Taken together, our results suggest that the RNase activity of SBL leads to breast cancer cell death through the activation of p38 MAPK followed by the activation of caspase-3/7. PMID:27513956

  8. RNase activity of sialic acid-binding lectin from bullfrog eggs drives antitumor effect via the activation of p38 MAPK to caspase-3/7 signaling pathway in human breast cancer cells.

    Science.gov (United States)

    Kariya, Yukiko; Tatsuta, Takeo; Sugawara, Shigeki; Kariya, Yoshinobu; Nitta, Kazuo; Hosono, Masahiro

    2016-10-01

    Sialic acid-binding lectin obtained from bullfrog eggs (SBL) induces cell death in cancer cells but not in normal cells. This antitumor effect is mediated through its ribonuclease (RNase) activity. However, the underlying molecular mechanisms remain unclear. We found that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was activated when SBL induced cell death in three human breast cancer cell lines: SK-BR-3, MCF-7, and MDA‑MB231. The suppression of p38 MAPK phosphorylation by a p38 MAPK inhibitor as well as short interference RNA knockdown of p38 MAPK expression significantly decreased cell death and increased the cell viability of SBL-treated MDA‑MB231 cells. H103A, an SBL mutant lacking in RNase activity, showed decreased SBL-induced cell death compared with native SBL. However, the loss of RNase activity of SBL had no effect on its internalization into cells. The H103A mutant also displayed decreased phosphorylation of p38 MAPK. Moreover, SBL promoted caspase‑3/7 activation followed by a cleavage of poly (ADP-ribose)-polymerase, whereas the SBL mutant, H103A, lost this ability. The SBL-induced caspase‑3/7 activation was suppressed by the p38 MAPK inhibitor, SB203580, as well as pan-caspase inhibitor, zVAD-fmk. In the presence of zVAD-fmk, the SBL-induced cell death was decreased. In addition, the cell viability of SBL-treated MDA‑MB231 cells recovered by zVAD-fmk treatment. Taken together, our results suggest that the RNase activity of SBL leads to breast cancer cell death through the activation of p38 MAPK followed by the activation of caspase‑3/7.

  9. Mensuration of sialic acid seric level in nelore cattle exposed and nonexposed to bracken fern (Pteridium aquilinum / Aferição da concentração sérica de ácido siálico em novilhas da raça nelore expostas e não expostas à samambaia (Pteridium aquilinum

    Directory of Open Access Journals (Sweden)

    Wilmar Sachetin Marçal

    2008-08-01

    Full Text Available The Pteridium aquilinum is one toxic plant present in several countries of the world. The chronic ingestion causes diseases to livestock with negative economics repercussion. In Paraná state the Pteridium aquilinum is present in 105 out 399 municipal districts existents. The high occurrence of the plant in many areas of the Paraná state and the wrong utilization of these areas for cattle breed increase the importance of research that look for means that epidemic control of intoxication. Because that research institutions in the Paraná state have looking for means to advance in diagnosis methods, especially to cattle suffering from Bovine Enzootic Hematuria. The biomarkers have been used in the diagnosis and postoperative follow-up of tumor in the human beings in a routinely bases for years. Researches about this subject were crescent in the medicine of companion animals, however still incipient about cattle. Specifically in the Bovine Enzootic Hematuria were verified that mucin, a substance present in the mucus from the mucosal surface of bladder, is produced by tumoral cells in reasonable accounts. Previous reports verified one relationship between the excessive mucus protein production by the bladder with hemangioma and high plasmatic concentration of the sialic acid. This suggests that sialic acid is associated with inflammatory response of the tumoral growth, and might be used such as tumoral biomarker.A Pteridium aquilinum é uma planta tóxica, disseminada em vários paises do mundo, cuja ingestão continua resulta em doenças com impacto negativo à pecuária bovina. No Paraná, esta presente em 105 dos 399 municípios do Estado. Por essa razão tem-se buscado por meios de controle epidemiológico da intoxicação, já que em algumas localidades do Paraná a planta está disseminada em muitas áreas utilizadas para cria e recria de bovinos. Assim sendo, as instituições de pesquisa do Estado têm buscado meios de diagnóstico precoce

  10. Surface-tension properties of hyaluronic Acid.

    Science.gov (United States)

    Knepper, P A; Covici, S; Fadel, J R; Mayanil, C S; Ritch, R

    1995-06-01

    The maintenance of flow channels in the trabecular meshwork is dependent, in part, on the patency of the trabecular spaces. Because the amount of hyaluronic acid decreases in the trabecular meshwork of patients with primary open-angle glaucoma, a change in surface tension may be one of the effects of hyaluronic acid on aqueous outflow. The surface-active properties of hyaluronic acid (concentration of 0.156-2.5 mg/ml; molecular weights of 100,000, 500,000, and 4,000,000) in deionized water, Ringer's lactate, Ringer's lactate plus 0.06 mg/ml bovine serum albumin, and mock aqueous solution were tested using the drop volume method. At a hyaluronic acid concentration of 0.312 mg/ml, surface tension decreased; at higher concentrations, a further decrease in surface tension was observed. In the presence of Ringer's lactate, the 100,000-MW hyaluronic acid was more active than the 4,000,000-MW hyaluronic acid. In the presence of Ringer's lactate plus bovine serum albumin or mock aqueous solution, the influence of surface tension of the 100,000-MW hyaluronic acid was moderated: with lower hyaluronic acid concentrations, the decline in surface tension was more than with Ringer's lactate, but with higher hyaluronic acid concentrations, the decline in surface tension was less than with Ringer's lactate. At high concentration, hyaluronic acid behaves like a non-Newtonian fluid, becomes more viscous, and may act to "seal" the trabecular space. The results of this study indicate that hyaluronic acid possesses surface-active properties, which is just one of several properties of hyaluronic acid that may influence aqueous outflow resistance.

  11. Surface Acidity of Amorphous Aluminum Hydroxide

    Institute of Scientific and Technical Information of China (English)

    K. FUKUSHI; K. TSUKIMURA; H. YAMADA

    2006-01-01

    The surface acidity of synthetic amorphous Al hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peaks in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous Al hydroxide rapidly transformed to crystalline bayerite at the alkaline condition (pH>10). The solution analyses after and during the titration experiments showed that the solubility of amorphous aluminum hydroxide, Ksp =aAl3+/a3H+,was 1010.3,The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved Al species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0.

  12. Acetic acid mediated interactions between alumina surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Kimiyasu, E-mail: sato.kimiyasu@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Y Latin-Small-Letter-Dotless-I lmaz, Hueseyin [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Gebze Institute of Technology, Materials Science and Engineering Department, 41400, Gebze-Kocaeli (Turkey); Ijuin, Atsuko; Hotta, Yuji; Watari, Koji [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan)

    2012-02-01

    Low-molecular-weight organic acids have been known to modify colloidal stability of alumina-based suspensions. We investigated interaction forces between alumina surfaces mediated by acetic acid which is one of the simplest organic acids. Forces between alumina surfaces were measured using the colloid-probe method of atomic force microscope (AFM). Repulsive forces attributed to steric repulsion due to adsorbed molecules and electrostatic repulsion dominated the interaction. Results of rheological characterization of the alumina slurry containing acetic acid supported the finding.

  13. 不同阶段母乳中唾液酸和铁水平分析%CHANGES OF SIALIC ACID AND IRON LEVELS IN HUMAN MILK AT DIFFERENT STAGES

    Institute of Scientific and Technical Information of China (English)

    阮莉莉; 华春珍; 洪理泉

    2015-01-01

    目的研究不同阶段母乳中唾液酸(sialic acid,SA)和铁的含量,为乳儿喂养和辅食添加及其神经发育评估提供科学依据。方法收集473份母乳(初乳191份,过渡乳115份,成熟乳109份和晚乳58份),母乳SA水平检测采用神经氨酸苷酶法,铁检测采用亚铁嗪法。组间 SA 水平比较采用方差分析,铁的比较采用非参数检验,相关性采用 Pearson 相关分析法。结果初乳 SA 平均浓度(1671.8±641.6)mg/L;过渡乳(1398.1±390.8)mg/L;成熟乳(419.5±292.0)mg/L,晩乳(262.8±80.9)mg/L,初乳 SA水平显著高于过渡乳,过渡乳 SA水平显著高于成熟乳,后者又显著高于晩乳(F=5.55,P=0.001)。初乳铁含量中位数0.07 mg/L,过渡乳0.09mg/L,成熟乳0.17 mg/L,晩乳0.21mg/L,初乳铁含量显著低于过渡乳(Z=2.61,P=0.009),过渡乳又显著低于成熟乳(Z=6.30,P<0.001),后者又显著低于晩乳(Z=2.87,P=0.004)。母乳中SA含量与月龄负相关(r=-0.677,P<0.001),铁含量与月龄正相关(r=0.333, P<0.001)。结论母乳中SA浓度随着月龄的增加逐渐下降,而铁的含量随着日龄的增加逐渐增高。[营养学报,2015,37(1):84-87]%Objective To study the levels of sialic acid (SA) and iron in human milks at different stages, and provide scientific basis for breast-milk feeding, supplementary food addition and neural development evaluation. Methods A total of 473 human milk samples, including 191 colostrum, 115 transition, 109 mature and 58 late milk samples, were collected. SA level was measured by neuraminidase assay method, while iron level was determined by ferrozine method. Analysis of variance was used to compare the differences in SA level and non-parametric test was used to compare the differences in iron level among different groups. Pearson correlation analysis method was used to analyze the correlation between the SA or iron levels

  14. 母体唾液酸对正常足月儿智能发育的影响%Effect of maternal sialic acid on intelligence development of normal term infants

    Institute of Scientific and Technical Information of China (English)

    李海英; 高薇薇; 邵志莉; 吴尤佳; 徐美玉

    2013-01-01

    Objective: To explore the effect of maternal sialic acid (SA) on intelligence development of normal term infants. Methods: ELISA was used to detect SA levels in venous blood samples of 150 normal pregnant women at (20 ±2) gestational week, (32 ± 2) gestational weeks, at birth and umbilical cord serum of their neonates, at 3 -4 days and 42 days after birth in breast milk; CDCC was used to evaluate the infants at 3 -4 months after birth, then mental development index (MDI) and physical development index (PDI) were obtained. Results: SA level in maternal blood was positively correlated with gestational week; SA level in umbilical cord blood was significantly lower than that in maternal blood, but there was no correlation between SA level in umbilical cord blood and maternal blood of term infants ; SA level in maternal blood was positively correlated with MDI and PDI of infants, but there was no correlation between SA level in maternal blood of term infants and MDI, PDI of infants. SA level in colostrum was significantly higher than that in mature milk, the levels of SA in colostrum and mature milk were positively correlated with MDI and PDI of infants. The correlations of MDI and PDI of infants with colostrum were higher than those with mature milk and umbilical cord blood. Conclusion: SA levels in umbilical cord blood and breast milk were closely correlated with intelligence development of term infants.%目的:探讨母体唾液酸(SA)对足月婴儿智能发育的影响.方法:用酶联免疫吸附法测定150例正常孕妇分别于妊娠(20±2)周、(32±2)周、足月静脉血及其新生儿脐血血清、产后3~4天与42天乳汁中的SA水平,对其婴儿于出生后3~4个月采用中国儿童发展中心制定的0~3岁婴幼儿智能发育量表(CDCC)进行评价,得出精神和运动发育指数(MDI和PDI).结果:母血SA水平与孕周正相关;脐血SA水平显著低于母血,但与足月母血无相关性;脐血SA水平与婴儿MDI、PDI正

  15. Effects of schisandrin B on serum sialic acid and ceruloplasmin in rat lungs exposed to silica%五味子乙素对染矽尘大鼠血清唾液酸和铜蓝蛋白的影响

    Institute of Scientific and Technical Information of China (English)

    樊林花; 刘田福; 郭民; 刘茂林

    2011-01-01

    Objective To investigate the effects of schisandrin B( Sch-B) on serum sialic acid and cerulopasmin in rats with silicosis.Methods Fofiy-eight rats were randomly divided into control group( n = 16) , silica group( n = 16) and Sch-B group( n = 16) . The 50 mg silicon dioxide was injected intratracheally in every rat in silica group and Sch-B group.while 1 ml physiologic saline was injected intratracheally in every rat in control group. From the first day after injection, rats were orally given Sch-B 80 mg/( kg·d) in Sch-B group,while the same dose of olive oil was given in control group and silica group. After treatment for 7 d and 28 d,eight rats in each group were sacrificed and samples were coUected. The serum sialic acid content and cerulopasmin activity were assayed by a spectrophotometer. The lung histopathalogical changes were observed after HE staining. Results HE staining showed that the lungs were normal in control group,while the lungs were damaged obviously in silica group and slighijy in Sch-B group. At 7 d,the content of sialic acid and the activity of cerulopasmin had no significant difference among 3 groups( P > 0. 05 ) . At 28 d.the content of SA and the activity of CP were significantly higher in silica group than in cotrol group ( P < 0. 01) , and they were significanLly lower in Sch-B group than in silica group( P <0. 05). Conclusion Sch-B could inhibit the increase of serum SA content and CP activity.%目的 观察五味子乙素(schisandrin B,Sch-B)对染矽尘大鼠血清唾液酸(sialic acid,SA)和铜蓝蛋白(cerulopasmin,CP)的影响. 方法 将48只大鼠随机分为对照组、染矽尘组、Sch-B干预组,每组16只.采用暴露式气管内注入法给染矽尘组和Sch-B干预组大鼠一次性染矽尘(50 mg/只),同法对照组大鼠给予生理盐水(1 ml/只).染尘后第1天开始灌胃给药,Sch-B干预组给予Sch-B 80 mg/(kg · d),其他组给予等体积的橄榄油.药物干预7 d和28 d后,各组分别取8只大鼠

  16. Salicylic acid electrooxidation. A surface film formation

    Energy Technology Data Exchange (ETDEWEB)

    Baturova, M.D.; Vedenjapin, A.; Baturova, M.M. [N.D. Zelinsky Inst. of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Weichgrebe, D.; Danilova, E.; Rosenwinkel, K.H. [Univ. of Hannover, Inst. of Water Quality and Waste Management Hannover (Germany); Skundin, A. [A.N. Frumkin Inst. of Electrochemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2003-07-01

    A possibility to use electrochemical treatment for salicylic acid (SA) removal from waste water was studied. It was found that SA can be oxidized at platinum anode with formation of harmless products. Features of anodic process, in particular, formation of solid film on anode surface as well as properties of the film were investigated. (orig.)

  17. Nucleic acid interactions with pyrite surfaces

    Science.gov (United States)

    Mateo-Martí, E.; Briones, C.; Rogero, C.; Gomez-Navarro, C.; Methivier, Ch.; Pradier, C. M.; Martín-Gago, J. A.

    2008-09-01

    The study of the interaction of nucleic acid molecules with mineral surfaces is a field of growing interest in organic chemistry, origin of life, material science and biotechnology. We have characterized the adsorption of single-stranded peptide nucleic acid (ssPNA) on a natural pyrite surface, as well as the further adsorption of ssDNA on a PNA-modified pyrite surface. The characterization has been performed by means of reflection absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) techniques. The N(1s) and S(2p) XPS core level peaks of PNA and PNA + DNA have been decomposed in curve-components that we have assigned to different chemical species. RAIRS spectra recorded for different concentrations show the presence of positive and negative adsorption bands, related to the semiconducting nature of the surface. The combination of the information gathered by these techniques confirms that PNA adsorbs on pyrite surface, interacting through nitrogen-containing groups of the nucleobases and the iron atoms of the surface, instead of the thiol group of the molecule. The strong PNA/pyrite interaction inhibits further hybridization of PNA with complementary ssDNA, contrary to the behavior reported on gold surfaces.

  18. H.p.l.c. of oligo(sialic acids). Application to the determination of the minimal chain length serving as exogenous acceptor in the enzymic synthesis of colominic acid.

    Science.gov (United States)

    Ferrero, M A; Luengo, J M; Reglero, A

    1991-12-15

    A rapid, sensitive and easy h.p.l.c. method was developed for the quantitative analysis of oligosialic acids. This procedure which permits the complete separation (in 23 min) of several sialyloligomers with a degree of polymerization of between 1 and 16, has been employed to establish the minimal chain length of oligomer accepted, as an exogenous acceptor, by Escherichia coli K-235 sialytransferase complex (ST) leading to the synthesis in vitro of colominic acid. We showed that this membrane-bound enzyme catalyses the direct transfer of Neu5Ac residues (one by one) from CMP-Neu5Ac to an exogenous acceptor molecule which contains at least three Neu5Ac residues. Free Neu5Ac or (Neu5Ac)2 were not recognized as substrates, whereas the maximal rate of polymer elongation was achieved when (Neu5Ac)5 was used as substrate.

  19. 单唾液酸四己糖神经节苷脂钠联合中频电疗治疗小儿中枢神经协调障碍的临床效果%Clinical Effect of Single Sialic Acid Four Hexose Ganglioside Sodium Combined With Intermediate Frequency Electrotherapy on Treating Pediatric Central Nervous Coordination Disorder

    Institute of Scientific and Technical Information of China (English)

    高岭; 党晓慧; 申改青

    2015-01-01

    Objective To observe the clinical curative effect of single sialic acid four hexose ganglioside sodium combined with intermediate frequency electrotherapy on treatment of children's central nervous coordination disorder, and analyze its clinical application value.Methods180 childern with central nervous coordination disorder were selected as research object, they were divided into observation group and control group, with 90 cases in each group, children in control group were given conventional rehabilitation treatment, and observation group were given single sialic acid four hexose ganglioside sodium combined with intermediate frequency electrotherapy treatment based on traditional rehabilitation therapy, the clinical effects, the indicators score (GESELL), disturbance of consciousness, abnormal muscle tone, the original reflection anomaly in two groups were observed.Results After treatment, the GESELL score of two groups were obviously improved, the differences were statistically significant (P<0.05), the GESELL score of observation group were Signiifcantly higher than the control group, the differences were statistically signiifcant (P<0.05), the duration of disturbance of consciousness, muscle tension, primitive relfex abnormalities in two groups were compared, the differences were statistically signiifcant (P<0.05).ConclusionSingle sialic acid four hexose ganglioside sodium combined with intermediate frequency electrotherapy has obvious curative effect on treating pediatric central nervous coordination disorder, this method has certain application value in clinic.%目的:观察单唾液酸四己糖神经节苷脂钠联合中频电疗治疗小儿中枢神经协调障碍的临床效果,分析其临床应用价值。方法选取中枢神经协调障碍患儿180例作为研究对象,分为观察组和对照组,每组患者均为90例,对照组患儿给予传统的康复治疗,观察组患儿在传统康复治疗的基础上给予单唾液酸四己糖

  20. Profiling transition-state configurations on the Trypanosoma cruzi trans-sialidase free-energy reaction surfaces.

    Science.gov (United States)

    Rogers, Ian L; Naidoo, Kevin J

    2015-01-22

    Enzymatically catalyzed reactions pass from reactants to products via transition states that are short-lived and potentially characterized from free-energy reaction surfaces. We compute the reaction surface for Trypanosoma cruzi trans-sialidase using the Free Energy from Adaptive Reaction Coordinate Forces method. The reaction coordinates are the bonds between the sialic acid and the leaving group (TYR342) and the sialic acid and the nucpleophile (ASP59). We are able to track progress of the reaction trajectories up to (incomplete), about (recrossed), and across (crossed) the col that divides the reactant (covalent intermediate) and product (Michaelis complex) surfaces. More than 40 transition state configurations were isolated from these trajectories, and the sialic acid substrate conformations were analyzed as well as the substrate interactions with the nucleophile and catalytic acid/base. A successful barrier crossing requires that the substrate passes through a family of E5, (4)H5, and (6)H5 pucker conformations. These puckers interact slightly differently with the enzyme. The E5 and (4)H5 conformations have a high-frequency hydrogen bonding with Asp96, while (6)H5 puckers show increased hydrogen bonding between sialic acid O-8-Glu230. Our analysis of Trypanosoma cruzi trans-sialidase configurations that populate the col separating the reactant from product surfaces brings new evidence to the prevailing premise that there are several pathways from reactant to product passing through the saddle and successful product formation is not restricted to the minimum energy path and transition state.

  1. 胞外唾液酸酶造成工程中国仓鼠卵巢细胞株所产人源重组促红素唾液酸含量降低%Extracellular sialidase degrades sialic acid in recombinant human erythropoietin produced by an industrial Chinese hamster ovary cell strain

    Institute of Scientific and Technical Information of China (English)

    刘颖慰; 周祥山; 刘海峰; 宋志伟; 张元兴

    2012-01-01

    To investigate the N-glycosylation characteristics of recombinant human erythropoietin (rhEPO) produced by an industrial Chinese hamster ovary (CHO) cell line that is currently used in a large scale manufacturing process, we cultured this cell strain in static mode. The produced rhEPO in the culture supernatant was analyzed using isoelectric focusing (IEF) and Ricinus communis agglutinin-I (RCA-I) lectin precipitation. The lactate dehydrogenase (LDH) and sialidase activity in the serum-free supernatant were assayed as well. The analyses revealed that this cell strain could produce rhEPO with high sialic acid content, but during prolonged culture, cell viability decreased with time whilst the activity of sialidase present in the supernatant increased. The loss in rhEPO quality was due to a decrease in terminal sialic acid on the N-glycans, caused by sialidase degradation. The methods and findings in this paper serve as basis for further investigation of industrial production process.%为了对工程中国仓鼠卵巢(CHO)细胞所产人源重组促红素(rhEPO)的N-糖基化特点进行考察,静置培养工程细胞后,通过等电聚焦和凝集素共沉淀对培养上清中的rhEPO进行分析,并对无血清培养上清中乳酸脱氢酶(LDH)和唾液酸酶活性进行检测,发现这株CHO细胞可以表达唾液酸含量较高的rhEPO蛋白.但是随着培养时间的延长,细胞的存活率逐渐降低,死亡的细胞将胞内的唾液酸酶释放到胞外,唾液酸酶的降解作用会造成N-糖链分枝末端的唾液酸占有率降低,导致rhEPO蛋白糖基化形态的变化.所使用的方法及得到的结果为进一步对工业过程进行分析提供了参考.

  2. Ácido siálico sérico, carga aniónica y agregación eritrocitaria en pacientes diabéticos e hipertensos Serum sialic acid, cellular anionic charge and erythrocyte aggregation in diabetic and hypertensive patients

    Directory of Open Access Journals (Sweden)

    Natalia Lebensohn

    2009-06-01

    Full Text Available El objetivo de este trabajo fue estudiar la relación del ácido siálico sérico (AS y la carga aniónica eritrocitaria (CAE con la agregación eritrocitaria en dos grupos de pacientes: diabéticos (DBT n= 20 e hipertensos (HTA n= 21, comparados con un grupo control (n= 20. Se trabajó con sangre anticoagulada con EDTA y suero. La agregación eritrocitaria se estudió por observación microscópica de los agregados y cuantificación a través de un parámetro de forma denominado ASP (Aggregation Shape Parameter. La CAE se determinó por unión a colorante alcian blue y el AS por método espectrofotométrico con reactivo de Erlich. Los valores de ASP y AS resultaron significativamente aumentados en los HTA y DBT respecto de los normales. Los HTA y DBT presentaron agregados amorfos, lo que se refleja en los valores alterados de ASP, significativamente mayores (p The aim of this work was to study the relationship between serum sialic acid (SSA and erythrocyte anionic charge (EAC with erythrocyte aggregation in two groups: diabetic (DBT, n=20 and hypertensive (HT, n=21 patients, compared to a control group (n=20. We worked with anticoagulated blood with EDTA and serum. The erythrocyte aggregation was studied by microscopically observing and quantifying aggregates using an ASP (Aggregate Shape Parameter. The EAC was determined by binding an Alcian blue dye to the membrane sialic acid and SSA was determined by spectrophotometric method with an Erlich reactant. The values of ASP and SSA increased significantly in HT and DBT patients compared to the control group. The HT and DBT groups showed amorphous aggregates, evident in an alteration in the values of ASP, which were significantly higher ( p< 0.005 than in healthy patients. The EAC values were much lower in HT and DBT patients than in the control group (p < 0.0001. In this work, abnormalities in the erythrocyte aggregation could be detected by the values of ASP, EAC and SSA, which might be involved

  3. Simultaneous Determination of Neutral Sugar, Uronic Acid, Amino Sugar and Sialic Acid of Polysaccharides by Gas Chromatography%气相色谱法同时测定多糖中的中性糖、糖醛酸、氨基糖和唾液酸

    Institute of Scientific and Technical Information of China (English)

    李波; 芦菲; 田素玉

    2011-01-01

    Neutral sugar, uronic acid, amino sugar and sialic acid were effectively determined simultaneously by gas chromatography after methanolysis and trimethylsilylation. Three standard monosaccharide mixtures (including Ara, Rha, Fuc, Xyl, Man, Gal, Gle, GlcA, GalA, GalNAc, GlcNAc, Neu5Ac) and two polysaccharide samples (okara polysaccharide DFP, Coprinus comatus polysaccharide F32) were methanolysis by 1 mol/L HC1/methanol at 85 ℃ for 18 -24 h, neutralized with Ag2CO3 and re-N-acetylated by adding acetic anhydride for 24 h in the dark. After removing the silver salts, the dried residue was trimethylsilylated by adding silylation reagent (pyridine/hexamethyldisilazane/chlorotrimethylsilane = 5: 1:1 ) for 30 min at room temperature. Then the final products were analyzed by gas chromatography. This method needs fewer amount of sample, and has higher sensitivity and resolution. It can simultaneous detect kinds of monosaccharides. It will have a great potential for application.%采用甲醇解和硅烷衍生化,用气相色谱法同时测定样品中的中性糖、糖醛酸、N-乙酰氨基糖和唾液酸,取得了很好的效果。3种标准单糖混合物(包含阿拉伯糖、鼠李糖、岩藻糖、木糖、甘露糖、半乳糖、葡萄糖、葡萄糖醛酸、半乳糖醛酸、N-乙酰半乳糖、N-乙酰葡萄糖、5-乙酰唾液酸)和2种多糖样品(豆腐渣多糖DFP、鸡腿菇多糖F32)用1mol/L盐酸甲醇在85℃反应18~24h,碳酸银中和,加入乙酸酐室温暗处反应24h,使氨基糖重新引入N-乙酰基,除银盐,干燥,加入硅烷化试剂[y(吡啶):y(六甲基二硅氨烷):V(三甲基氯硅烷)=5:1:1),室温放置30min,最后用气相色谱进行分析。

  4. 单唾液酸四己糖神经节苷脂钠治疗糖尿病痛性神经病变的观察%Clinical Value of Single Sialic Acid Four Hexose Ganglioside Sodium in the Treatment of Painful Diabetic Neuropathy

    Institute of Scientific and Technical Information of China (English)

    甘喜

    2014-01-01

    目的:探讨单唾液酸四己糖神经节苷脂钠治疗糖尿病痛性神经病变的疗效。方法将来我院内分泌科就诊的80例糖尿病痛性神经病变患者采取随机双盲对照原则分为治疗组和对照组,其中对照组38例患者在进行常规用药治疗的同时给予硫辛酸注射液治疗,治疗组42例患者在上述治疗的基础上加用单唾液酸四己糖神经节苷脂钠治疗,分析不同的用药方案对患者所带来的治疗效果。结果统计分析结果表明,治疗组患者临床治疗总有效率(92.9%)明显高于对照组(76.3%),差异具有统计学意义(P<0.05),无明显不良反应。结论单唾液酸四己糖神经节苷脂钠注射液治疗糖尿病神经性病变安全有效,值得进一步研究。%Objective To alleviate diabetic neuropathy pain, to analyze and explore the curative effect of lipoic acid combined with single sialic acid four hexose ganglioside sodium. Methods 80 patients with painful diabetic neuropathy from Department of En-docrinology in our hospital were randomly divided into the treatment group and the control group according to double blind control prin-ciple. 38 patients in the control group were given, besides routine drug, Thioctic Acid Injection. 42 patients in the treatment group were treated with single saliva acid four hexose ganglioside sodiumt. Curative effects of different medication schemes were analyzed. Results The results of statistical analysis showed that the total clinical treatment effective rate (92. 9%) of the observation group was significantly higher than that of the control group (76. 3% patients). There was significant difference between the two groups (P<0. 05). Conclusion For patients with diabetes neuropathy, conventional treatment combined with single sialic acid four hexose gan-glioside sodium injection can control the clinical symptoms of the patients effectively as well as improve the life quality of patients signif-icantly, which

  5. Boronic acid-tethered amphiphilic hyaluronic acid derivative-based nanoassemblies for tumor targeting and penetration.

    Science.gov (United States)

    Jeong, Jae Young; Hong, Eun-Hye; Lee, Song Yi; Lee, Jae-Young; Song, Jae-Hyoung; Ko, Seung-Hak; Shim, Jae-Seong; Choe, Sunghwa; Kim, Dae-Duk; Ko, Hyun-Jeong; Cho, Hyun-Jong

    2017-02-16

    (3-Aminomethylphenyl)boronic acid (AMPB)-installed hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs), including manassantin B (MB), were fabricated for tumor-targeted delivery. The amine group of AMPB was conjugated to the carboxylic acid group of hyaluronic acid (HA) via amide bond formation, and synthesis was confirmed by spectroscopic methods. HACE-AMPB/MB NPs with a 239-nm mean diameter, narrow size distribution, negative zeta potential, and >90% drug encapsulation efficiency were fabricated. Exposed AMPB in the outer surface of HACE-AMPB NPs (in the aqueous environment) may react with sialic acid of cancer cells. The improved cellular accumulation efficiency, in vitro antitumor efficacy, and tumor penetration efficiency of HACE-AMPB/MB NPs, compared with HACE/MB NPs, in MDA-MB-231 cells (CD44 receptor-positive human breast adenocarcinoma cells) may be based on the CD44 receptor-mediated endocytosis and phenylboronic acid-sialic acid interaction. Enhanced in vivo tumor targetability, infiltration efficiency, and antitumor efficacies of HACE-AMPB NPs, compared with HACE NPs, were observed in a MDA-MB-231 tumor-xenografted mouse model. In addition to passive tumor targeting (based on an enhanced permeability and retention effect) and active tumor targeting (interaction between HA and CD44 receptor), the phenylboronic acid-sialic acid interaction can play important roles in augmented tumor targeting and penetration of HACE-AMPB NPs. STATEMENT OF SIGNIFICANCE: (3-Aminomethylphenyl)boronic acid (AMPB)-tethered hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs), including manassantin B (MB), were fabricated and their tumor targeting and penetration efficiencies were assessed in MDA-MB-231 (CD44 receptor-positive human adenocarcinoma) tumor models. MB, which exhibited antitumor efficacies via the inhibition of angiogenesis and hypoxia inducible factor (HIF)-1, was entrapped in HACE-AMPB NPs in this study. Phenylboronic acid located in the outer surface

  6. Surface Propensity of Atmospherically Relevant Amino Acids Studied by XPS.

    Science.gov (United States)

    Mocellin, Alexandra; Gomes, Anderson Herbert de Abreu; Araújo, Oscar Cardoso; de Brito, Arnaldo Naves; Bjorneholm, Olle

    2017-03-30

    Amino acids constitute an important fraction of the water-soluble organic nitrogen (WSON) compounds in aerosols and are involved in many processes in the atmosphere. In this work, we applied XPS to study aqueous solutions of four amino acids: glycine, alanine, valine and methionine, in their zwitterionic forms. We found that amino acids with hydrophilic side chains and smaller size, GLY and ALA, tend to stay in the bulk of the liquid, while the hydrophobic and bigger amino acids, VAL and MET, are found to concentrate more on the surface. We found experimental evidences that the amino acids have preferential orientation relative to the surface, with the hydrophobic side chain being closer to the surface than the hydrophilic carboxylate group. The observed amino acid surface propensity has implications in atmospheric science as the surface interaction play a central role in cloud droplet formation, and they should be considered in climate models.

  7. 单唾液酸四己糖神经节苷脂钠联合中频电疗治疗小儿中枢神经协调障碍的临床效果%Clinical effect of single sialic acid four hexose ganglioside sodium com-bined with intermediate frequency electrotherapy on treating pediatric central nervous coordination disorder

    Institute of Scientific and Technical Information of China (English)

    钟守萍

    2015-01-01

    Objective To observe the clinical curative effect of single sialic acid four hexose ganglioside sodium com-bined with intermediate frequency electrotherapy on treatment of children's central nervous coordination disorder, and analyze its clinical application value. Methods From 2014 January to January 2015, in the First People's Hospital of Neijiang City, 100 childern with central nervous coordination disorder were selected as research object and retrospec-tively analyzed, according to the different treatment method, they were divided into experiment group and control group, with 50 cases in each group. children in control group were given conventional rehabilitation treatment, and experimen group were given single sialic acid four hexose ganglioside sodium combined with intermediate frequency electrotherapy treatment based on traditional rehabilitation therapy. The clinical effects, the indicators score of GESELL, disturbance of consciousness, abnormal muscle tone, the original reflection anomaly in two groups were observed. Results There was no statistically significant difference between GESELL score of two groups before treatment (P>0.05);after treat-ment, big movement scores [(38.78±10.26), (31.06±9.74) scores], fine motor scores [(43.26±8.98), (38.05±7.62) scores] and adaptability scores [(59.35±8.26), (52.17±8.86) scores] of the experimen group and control group were compared, the differences were statistically significant (P 0.05). After the treatment, in experimen group, excellent were 23 cases, effective were 26 cases, invalid was 1 case, the clinical total effective rate was 98.0%; in control group, excellent were 15 cases, effective 24 cases, invalid were 11 cases, the clinical total ef-fective rate was 78.0%, the clinical total effective rate in two groups were compared, the difference was statistically sig-nificant (P0.05);两组患儿治疗后各项GESELL评分与治疗前比较,差异有统计学意义(P0.05)。治

  8. Dye Indicators for Acidic or Basic Surface Contamination

    Science.gov (United States)

    Lakin, A.; Schuler, F.

    1984-01-01

    Application of pH-sensitive dye solution serves as test for acidic or basic contamination of critical bonding surface. Aqueous solution of 0.1 percent Direct Red No. 28 capable of indicating acid activating solution down to 10 parts per million on hardware and tooling. Dye did not cause detectable contamination of surface.

  9. Acidity of edge surface sites of montmorillonite and kaolinite

    NARCIS (Netherlands)

    Liu, X.; Lu, X.; Sprik, M.; Cheng, J.; Meijer, E.J.; Wang, R.

    2013-01-01

    Acid-base chemistry of clay minerals is central to their interfacial properties, but up to now a quantitative understanding on the surface acidity is still lacking. In this study, with first principles molecular dynamics (FPMD) based vertical energy gap technique, we calculate the acidity constants

  10. Acid-base bifunctional catalytic surfaces for nucleophilic addition reactions.

    Science.gov (United States)

    Motokura, Ken; Tada, Mizuki; Iwasawa, Yasuhiro

    2008-09-01

    This article illustrates the modification of oxide surfaces with organic amine functional groups to create acid-base bifunctional catalysts, summarizing our previous reports and also presenting new data. Immobilization of organic amines as bases on inorganic solid-acid surfaces afforded highly active acid-base bifunctional catalysts, which enabled various organic transformations including C--C coupling reactions, though these reactions did not proceed with either the homogeneous amine precursors or the acidic supports alone. Spectroscopic characterization, such as by solid-state MAS NMR and FTIR, revealed not only the interactions between acidic and basic sites but also bifunctional catalytic reaction mechanisms.

  11. Effect of acidic agents on surface roughness of dental ceramics

    Directory of Open Access Journals (Sweden)

    Boonlert Kukiattrakoon

    2011-01-01

    Conclusion: Acidic agents used in this study negatively affected the surface of ceramic materials. This should be considered when restoring the eroded tooth with ceramic restorations in patients who have a high risk of erosive conditions.

  12. Engineering novel cell surface chemistry for selective tumor cell targeting

    Energy Technology Data Exchange (ETDEWEB)

    Bertozzi, C.R. [Univ. of California, Berkeley, CA (United States)]|[Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    A common feature of many different cancers is the high expression level of the two monosaccharides sialic acid and fucose within the context of cell-surface associated glycoconjugates. A correlation has been made between hypersialylation and/or hyperfucosylation and the highly metastatic phenotype. Thus, a targeting strategy based on sialic acid or fucose expression would be a powerful tool for the development of new cancer cell-selective therapies and diagnostic agents. We have discovered that ketone groups can be incorporated metabolically into cell-surface associated sialic acids. The ketone is can be covalently ligated with hydrazide functionalized proteins or small molecules under physiological conditions. Thus, we have discovered a mechanism to selectively target hydrazide conjugates to highly sialylated cells such as cancer cells. Applications of this technology to the generation of novel cancer cell-selective toxins and MRI contrast reagents will be discussed, in addition to progress towards the use of cell surface fucose residues as vehicles for ketone expression.

  13. Oxalic acid adsorption states on the clean Cu(110) surface

    Science.gov (United States)

    Fortuna, Sara

    2016-11-01

    Carboxylic acids are known to assume a variety of configurations on metallic surfaces. In particular oxalic acid on the Cu(110) surface has been proposed to assume a number of upright configurations. Here we explore with DFT calculations the possible structures that oxalic acid can form on copper 110 at different protonation states, with particular attention at the possibility of forming structures composed of vertically standing molecules. In its fully protonated form it is capable of anchoring itself on the surface thanks to one of its hydrogen-free oxygens. We show the monodeprotonated upright molecule with two oxygens anchoring it on the surface to be the lowest energy conformation of a single oxalic molecules on the Cu(110) surface. We further show that it is possible for this configuration to form dense hexagonally arranged patterns in the unlikely scenario in which adatoms are not involved.

  14. Titratable Acidity and Alkalinity of Red Soil Surfaces

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1993-01-01

    The surfaces of red soils have an apparent amphoteric character,carrying titratable acidity and titratable alkalinity simultaneously.The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter,while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces.The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils.The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution,free iron oxide(Fed) extracted with sodium dithionite-citrate-bicarbonate(DCB) and clays,but also with the zero point of charge (ZPC) of the samples.Organic matter made an important contribution to the titratable acidity.the titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed.The titratable acidity and titratable alkalinity of red soils were influenced by parent materials,being in the order of red soil derived from basalt> that from tuff> that from granite.The titratable acidity and titratable alkalinity ware closely related with origination of the variable charges of red soils,and to a certain extent were responsible for variable negative and positive charges of the soils.

  15. Interactions between acid- and base-functionalized surfaces

    NARCIS (Netherlands)

    Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

    2002-01-01

    In this paper we present an AFM force study on interactions between chemically modified surfaces. Surfaces with terminal groups of either NH2 or COOH were obtained by chemisorption of a silane-based compound (3-amino-propyltriethoxysilane) on silica or a thiol compound (11-mercapto undecanoic acid)

  16. Surface Modification of SnO2 with Phosphonic Acids

    Directory of Open Access Journals (Sweden)

    Ramona Gheonea

    2017-01-01

    Full Text Available The aim of the present work was the study of phosphonic acids grafting on the surface of SnO2 at different molar ratios. In this paper we describe the functionalization of SnO2 surfaces with phosphonic acids RPO(OH2. The surface modification process was achieved by using phenyl-phosphonic acid (PPA and vinyl-phosphonic acid (VPA. The synthesized materials were investigated by using FT-IR, TGA (in air and in nitrogen, EDX, ESEM, and TEM methods. This synthetic approach has many advantages: films with optical quality and controlled thickness can be obtained using low temperatures and cheap raw materials, by using “green chemistry” synthetic routes. The hybrid materials have structures diversity and fascinating applications, attracting attention for a long time, due to their potential.

  17. Superhydrophobic alumina surface based on stearic acid modification

    Energy Technology Data Exchange (ETDEWEB)

    Feng Libang, E-mail: lepond@hotmail.com [School of Mechatronic Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China); Zhang Hongxia; Mao Pengzhi; Wang Yanping; Ge Yang [School of Mechatronic Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China)

    2011-02-15

    A novel superhydrophobic alumina surface is fabricated by grafting stearic acid layer onto the porous and roughened aluminum film. The chemical and phase structure, morphology, and the chemical state of the atoms at the superhydrophobic surface were investigated by techniques as FTIR, XRD, FE-SEM, and XPS, respectively. Results show that a super water-repellent surface with a contact angle of 154.2{sup o} is generated. The superhydrophobic alumina surface takes on an uneven flowerlike structure with many nanometer-scale hollows distribute in the nipple-shaped protrusions, and which is composed of boehmite crystal and {gamma}-Al{sub 2}O{sub 3}. Furthermore, the roughened and porous alumina surface is coated with a layer of hydrophobic alkyl chains which come from stearic acid molecules. Therefore, both the roughened structure and the hydrophobic layer endue the alumina surface with the superhydrophobic behavior.

  18. Cerebellar ataxia with elevated cerebrospinal free sialic acid (CAFSA).

    NARCIS (Netherlands)

    Mochel, F.; Sedel, F.; Vanderver, A.; Engelke, U.F.H.; Barritault, J.; Yang, B.Z.; Kulkarni, B.; Adams, D.R.; Clot, F.; Ding, J.H.; Kaneski, C.R.; Verheijen, F.W.; Smits, B.W.; Seguin, F.; Brice, A.; Vanier, M.T.; Huizing, M.; Schiffmann, R.; Durr, A.; Wevers, R.A.

    2009-01-01

    In order to identify new metabolic abnormalities in patients with complex neurodegenerative disorders of unknown aetiology, we performed high resolution in vitro proton nuclear magnetic resonance spectroscopy on patient cerebrospinal fluid (CSF) samples. We identified five adult patients, including

  19. Surface reactions of iron - enriched smectites: adsorption and transformation of hydroxy fatty acids and phenolic acids

    Science.gov (United States)

    Polubesova, Tamara; Olshansky, Yaniv; Eldad, Shay; Chefetz, Benny

    2014-05-01

    Iron-enriched smectites play an important role in adsorption and transformation of soil organic components. Soil organo-clay complexes, and in particular humin contain hydroxy fatty acids, which are derived from plant biopolymer cutin. Phenolic acids belong to another major group of organic acids detected in soil. They participate in various soil processes, and are of concern due to their allelopathic activity. We studied the reactivity of iron-enriched smectites (Fe(III)-montmorillonite and nontronite) toward both groups of acids. We used fatty acids- 9(10),16-dihydroxypalmitic acid (diHPA), isolated from curtin, and 9,10,16-trihydroxypalmitic acid (triHPA); the following phenolic acids were used: ferulic, p-coumaric, syringic, and vanillic. Adsorption of both groups of acids was measured. The FTIR spectra of fatty acid-mineral complexes indicated inner-sphere complexation of fatty acids with iron-enriched smectites (versus outer-sphere complexation with Ca(II)-montmorillonite). The LC-MS results demonstrated enhanced esterification of fatty acids on the iron-enriched smectite surfaces (as compared to Ca(II)-montmorillonite). This study suggests that fatty acids can be esterified on the iron-enriched smectite surfaces, which results in the formation of stable organo-mineral complexes. These complexes may serve as a model for the study of natural soil organo-clay complexes and humin. The reaction of phenolic acids with Fe(III)-montmorillonite demonstrated their oxidative transformation by the mineral surfaces, which was affected by molecular structure of acids. The following order of their transformation was obtained: ferulic >syringic >p-coumaric >vanillic. The LC-MS analysis demonstrated the presence of dimers, trimers, and tetramers of ferulic acid on the surface of Fe(III)-montmorillonite. Oxidation and transformation of ferulic acid were more intense on the surface of Fe(III)-montmorillonite as compared to Fe(III) in solution due to stronger complexation on

  20. The study of the relationship between sialic acid of human milk and the early intellectual development of term infants%母乳唾液酸与足月婴儿早期智能发育关系的研究

    Institute of Scientific and Technical Information of China (English)

    邵志莉; 吴尤佳; 徐美玉

    2014-01-01

    目的:探讨母乳唾液酸(sialic acid,SA)与足月婴儿早期智能发育的关系。方法:采用前瞻性队列研究,调查了100组母亲及其婴儿,生后3个月采用0~3岁婴幼儿智能发育量表(Children’s Development Center of China,CDCC)评价智能,得出智力发育指数(mental development index,MDI)和运动发育指数(psychomotive development index,PDI)。用酶联免疫吸附法测定3 d、42 d、3月的母乳和42 d、3月的婴儿随机尿SA水平。分析母乳SA与婴儿智能发育的关系。结果:80组对象数据完整,生后3 d、42 d、3月的母乳SA水平随时间逐渐下降(P<0.01);42 d与3月婴儿随机尿SA水平差异无统计学意义。42 d时婴儿尿SA与母乳SA正相关(r=0.803,P<0.01),而在3月时无相关性。3 d、42 d、3月的母乳SA与MDI的相关系数分别为0.708、0.408、0.594,P<0.01;与PDI的相关系数分别为0.661、0.455、0.471,P<0.01。婴儿按MDI与PDI分值分成高、中、低3组,比较3组间的三阶段母乳SA水平,发现智能高组母乳SA高,智能低组母乳SA低(P<0.05)。结论:母乳尤其是初乳SA水平与婴儿早期智能发育密切相关,提高乳母SA摄入量有益于婴儿早期智能发育。%Objective: To investigate the relationships between sialic acid(SA) of human milk and the early intellectual de-velopment of term infants. Methods: The present research was a prospective cohort study and 100 pairs of mothers-infants were recruited. All infants of 3 months old were evaluated by Children’s Development Center of China(CDCC) to obtain the mental and psycho-motor development index (MDI and PDI). All samples were collected from human milk at 3 days , 42 days and 3 months postpartum and random urine of infants at 42 days and 3 months after birth. SA levels were measured by en-zyme-linked immunosorbent assay to explore the correlation between SA levels of human milk at each time point and the ear-ly intellectual

  1. The Spectrum of SLC17A5-Gene Mutations Resulting in Free Sialic Acid–Storage Diseases Indicates Some Genotype-Phenotype Correlation

    Science.gov (United States)

    Aula, Nina; Salomäki, Pirjo; Timonen, Ritva; Verheijen, Frans; Mancini, Grazia; Månsson, Jan-Eric; Aula, Pertti; Peltonen, Leena

    2000-01-01

    Lysosomal free sialic acid–storage diseases include the allelic disorders Salla disease (SD) and infantile sialic acid–storage disease (ISSD). The defective gene, SLC17A5, coding for the lysosomal free sialic acid transporter was recently isolated by positional cloning. In the present study, we have identified a large number of mutations in SLC17A5 in patients presenting with either Salla disease or the ISSD phenotype. We also report for the first time the exon-intron boundaries of SLC17A5. All Finnish patients with SD (n=80) had a missense mutation changing a highly conserved arginine to cysteine (R39C); 91% of them were homozygotes for this old founder mutation. The compound-heterozygote patients, with the founder mutation in only one allele, presented with a more severe phenotype than did the homozygote patients. The same R39C mutation was also found both in most of the Swedish patients with SD and in a heterozygous form in five patients from central Europe who presented with an unusually severe (intermediate) SD phenotype. Ten different mutations, including deletions, insertions, and missense and nonsense mutations, were identified in patients with the most severe ISSD phenotype, most of whom were compound heterozygotes. Our results indicate some genotype-phenotype correlation in free sialic acid–storage diseases, suggesting that the phenotype associated with the homozygote R39C mutation is milder than that associated with other mutations. PMID:10947946

  2. Formic acid electrooxidation on Pd in acidic solutions studied by surface-enhanced infrared absorption spectroscopy.

    Science.gov (United States)

    Miyake, Hiroto; Okada, Tatsuhiro; Samjeské, Gabor; Osawa, Masatoshi

    2008-07-07

    A mechanistic study of electrocatalytic oxidation of formic acid on Pd in sulfuric and perchloric acids is reported. Surface-enhanced infrared absorption spectroscopy in the attenuated total reflection mode (ATR-SEIRAS) shows the adsorption of CO, bridge-bonded formate, bicarbonate, and supporting anions on the electrode surface. Poisoning of the Pd surface by CO, formed by dehydration of formic acid, is very slow and scarcely affects formic acid oxidation. The anions are adsorbed more strongly in the order of (bi)sulfate > bicarbonate > perchlorate, among which the most strongly adsorbed (bi)sulfate considerably suppresses formic acid oxidation in the double layer region. The oxidation is suppressed also at higher potentials in both acids by the oxidation of the Pd surface. Adsorbed formate is detected only when formic acid oxidation is suppressed. The results show that formate is a short-lived reactive intermediate in formic acid oxidation and is hence detected when its decomposition yielding CO(2) is suppressed. The high electrocatalytic activity of Pd can be ascribed to the high tolerance to CO contamination and also high catalytic activity toward formate decomposition.

  3. Surface interactions of cesium and boric acid with stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Grossman-Canfield, N.

    1995-08-01

    In this report, the effects of cesium hydroxide and boric acid on oxidized stainless steel surfaces at high temperatures and near one atmosphere of pressure are investigated. This is the first experimental investigation of this chemical system. The experimental investigations were performed using a mass spectrometer and a mass electrobalance. Surfaces from the different experiments were examined using a scanning electron microscope to identify the presence of deposited species, and electron spectroscopy for chemical analysis to identify the species deposited on the surface. A better understanding of the equilibrium thermodynamics, the kinetics of the steam-accelerated volatilizations, and the release kinetics are gained by these experiments. The release rate is characterized by bulk vaporization/gas-phase mass transfer data. The analysis couples vaporization, deposition, and desorption of the compounds formed by cesium hydroxide and boric acid under conditions similar to what is expected during certain nuclear reactor accidents. This study shows that cesium deposits on an oxidized stainless steel surface at temperatures between 1000 and 1200 Kelvin. Cesium also deposits on stainless steel surfaces coated with boric oxide in the same temperature ranges. The mechanism for cesium deposition onto the oxide layer was found to involve the chemical reaction between cesium and chromate. Some revaporization in the cesium hydroxide-boric acid system was observed. It has been found that under the conditions given, boric acid will react with cesium hydroxide to form cesium metaborate. A model is proposed for this chemical reaction.

  4. Loss of N-glycolylneuraminic acid in humans: Mechanisms, consequences, and implications for hominid evolution.

    Science.gov (United States)

    Varki, A

    2001-01-01

    The surface of all mammalian cells is covered with a dense and complex array of sugar chains, which are frequently terminated by members of a family of molecules called sialic acids. One particular sialic acid called N-glycolylneuraminic acid (Neu5Gc) is widely expressed on most mammalian tissues, but is not easily detectable on human cells. In fact, it provokes an immune response in adult humans. The human deficiency of Neu5Gc is explained by an inactivating mutation in the gene encoding CMP-N-acetylneuraminic acid hydroxylase, the rate-limiting enzyme in generating Neu5Gc in cells of other mammals. This deficiency also results in an excess of the precursor sialic acid N-acetylneuraminic acid (Neu5Ac) in humans. This mutation appears universal to modern humans, occurred sometime after our last common ancestor with the great apes, and happens to be one of the first known human-great ape genetic differences with an obvious biochemical readout. While the original selection mechanisms and major biological consequences of this human-specific mutation remain uncertain, several interesting clues are currently being pursued. First, there is evidence that the human condition can explain differences in susceptibility or resistance to certain microbial pathogens. Second, the functions of some endogenous receptors for sialic acids in the immune system may be altered by this difference. Third, despite the lack of any obvious alternate pathway for synthesis, Neu5Gc has been reported in human tumors and possibly in human fetal tissues, and traces have even been detected in normal human tissues. One possible explanation is that this represents accumulation of Neu5Gc from dietary sources of animal origin. Finally, a markedly reduced expression of hydroxylase in the brains of other mammals raises the possibility that the human-specific mutation of this enzyme could have played a role in human brain evolution.

  5. Fatty acid methyl ester profiles of bat wing surface lipids.

    Science.gov (United States)

    Pannkuk, Evan L; Fuller, Nathan W; Moore, Patrick R; Gilmore, David F; Savary, Brett J; Risch, Thomas S

    2014-11-01

    Sebocytes are specialized epithelial cells that rupture to secrete sebaceous lipids (sebum) across the mammalian integument. Sebum protects the integument from UV radiation, and maintains host microbial communities among other functions. Native glandular sebum is composed primarily of triacylglycerides (TAG) and wax esters (WE). Upon secretion (mature sebum), these lipids combine with minor cellular membrane components comprising total surface lipids. TAG and WE are further cleaved to smaller molecules through oxidation or host enzymatic digestion, resulting in a complex mixture of glycerolipids (e.g., TAG), sterols, unesterified fatty acids (FFA), WE, cholesteryl esters, and squalene comprising surface lipid. We are interested if fatty acid methyl ester (FAME) profiling of bat surface lipid could predict species specificity to the cutaneous fungal disease, white nose syndrome (WNS). We collected sebaceous secretions from 13 bat spp. using Sebutape(®) and converted them to FAME with an acid catalyzed transesterification. We found that Sebutape(®) adhesive patches removed ~6× more total lipid than Sebutape(®) indicator strips. Juvenile eastern red bats (Lasiurus borealis) had significantly higher 18:1 than adults, but 14:0, 16:1, and 20:0 were higher in adults. FAME profiles among several bat species were similar. We concluded that bat surface lipid FAME profiling does not provide a robust model predicting species susceptibility to WNS. However, these results provide baseline data that can be used for lipid roles in future ecological studies, such as life history, diet, or migration.

  6. Potential energy surface of the photolysis of isocyanic acid HNCO

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dissociation curves of the photolysis of the isocyanic acidHNCOHN+CO corresponding to the ground state (S0), the first triplet excited state (T1) and the first singlet excited state (S1) have been studied respectively at the UHF/6-311G** and CIS/6-311G** levels using ab initio method. The energy surface crossing points, S1/T1, T1/S0 and S1/S0, have been found and the characteristics of the energy minimum crossing point were given, based on which, the changes of the crossing points' geometries along the lower electronic energy surface and its end-result have been located according to the steepest descent principle. The computational result indicates that the photolysis of the isocyanic acid HNCOHN+CO has three competitive reaction channels ((A)-(C)), and from the kinetic piont of view, channel (A) is the most advantageous.

  7. Explosive enantiospecific decomposition of aspartic acid on Cu surfaces.

    Science.gov (United States)

    Mhatre, B S; Dutta, S; Reinicker, A; Karagoz, B; Gellman, A J

    2016-12-01

    Aspartic acid adsorbed on Cu surfaces is doubly deprotonated. On chiral Cu(643)(R&S) its enantiomers undergo enantiospecific decomposition via an autocatalytic explosion. Once initiated, the decomposition mechanism proceeds via sequential cleavage of the C3-C4 and C1-C2 bonds each yielding CO2, followed by conversion of the remaining species into N[triple bond, length as m-dash]CCH3.

  8. Poly(acrylic acid surface grafted polypropylene films: Near surface and bulk mechanical response

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available Radical photo-grafting polymerization constitutes a promising technique for introducing functional groups onto surfaces of polypropylene films. According to their final use, surface grafting should be done without affecting overall mechanical properties. In this work the tensile drawing, fracture and biaxial impact response of biaxially oriented polypropylene commercial films grafted with poly(acrylic acid (PAA were investigated in terms of film orientation and surface modification. The variations of surface roughness, elastic modulus, hardness and resistance to permanent deformation induced by the chemical treatment were assessed by depth sensing indentation. As a consequence of chemical modification the optical, transport and wettability properties of the films were successfully varied. The introduced chains generated a PAA-grafted layer, which is stiffer and harder than the neat polypropylene surface. Regardless of the surface changes, it was proven that this kind of grafting procedure does not detriment bulk mechanical properties of the PP film.

  9. Effect of ethylenediamine tetraacetic acid and etidronic acid on the surface roughness of Biodentine: in vitro

    Directory of Open Access Journals (Sweden)

    Özgür İlke Atasoy Ulusoy

    2017-01-01

    Full Text Available Objective: The aim of this study was to evaluate the effect of 9% etidronic acid (HEBP and 17% ethylenediamine tetraacetic acid (EDTA on the surface roughness of Biodentine. Materials and Method: Biodentine (Septodont was mixed according to the manufacturer’s instructions. Briefly, five drops of liquid were added into the capsule containing the powder. Then the capsule was placed in a triturator for 30 sec. The prepared mixture was placed into a mold (diameter: 5 mm, depth: 3 mm. The Biodentine surfaces were polished with silicon carbide abrasive papers. The surface roughness of 30 samples was measured at baseline using a portable surface roughness tester. For this purpose, a 5 mN force was applied onto three different locations of the samples with a speed of 0.8 mm/sec. The samples were divided into two groups according to the irrigation solution (n=15; first group was treated with 9% HEBP, and the second group was treated with 17% EDTA. The surface roughness of the samples was measured again after 1 and 2 min of irrigant application. Data were statistically analyzed using one-way ANOVA and independent sample t-test. Results: For HEBP, no significant difference was found between the surface roughness values at 0., 1., and 2 min (p=0.107; ANOVA. For EDTA, the surface roughness value at 1 min was significantly greater than the baseline value (p<0.001; t-test. The surface roughness changes at the two time periods were significantly different between the EDTA and HEBP groups (p=0.003 for 0-1 min passage, p=0.021 for 1-2 min passage. Conclusion: The use of 17% EDTA may result in deterioration of Biodentine’s surface during perforation repair and root canal treatment.

  10. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid

    Science.gov (United States)

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-01

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (Ep, 1.10 ≤ Ep ≤ 1.50 V), polarization time (tp, 100 ≤ tp ≤ 104 s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (dox). Because X1 > dox for the entire range of Ep, tp, and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Ptδ+-Oδ- surface dipole (μPtO), and the potential drop (Vox) and electric field (Eox) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide.

  11. 围产期唾液酸营养与足月儿早期智能发育相关性的研究%Relationship between the level of sialic acid during perinatal period and early intelligence development of full term infants

    Institute of Scientific and Technical Information of China (English)

    吴尤佳; 邵志莉; 高薇薇; 李海英; 徐美玉

    2014-01-01

    Objective To investigate the correlation between the status of sialic acid (SA) during perinatal period and early intelligence development of healthy full term infant,and to explore the effect of SA on the early intelligence development.Method A total of 127 pairs of healthy mothers-neonates in the Affiliated Hospital of Nantong University were recruited randomly in this prospective cohort study.The levels of SA from body fluids of mothers-neonates were measured by enzyme-linked immunosorbent assay,such as the full-term maternal and cord blood and the colostrum.The questionnaire surveys were carried out in mothers and mental development evaluation according to Children's Development Center of China (CDCC) were carried out in infants 3 to 4 months of age to obtain the mental development index (MDI) and psychomotor development index (PDI).Result A total of 120 pairs of maternal-neonatal subjects with complete data were included into statistical analysis.The levels of SA of maternal and cord blood and colostrum were (2.25 ±0.02),(1.21 ±0.01),and (5.01 ±0.06) mmol/L respectively.MDI and PDI of infants 3 to 4 months of age were (99.40 ± 1.87) and (98.53 ± 1.96).The analysis using multiple linear regression indicated that MDI was associated with SA levels of cord blood and colostrum (β =0.636,0.175,P <0.05),and PDI was also associated with them (β =0.502,0.262,P <0.05).The levels of SA of cord blood and colostrums were individually divided into high-level group and low-level one according to the median level.MDI and PDI in high-level group of cord blood were both significantly higher than that in lowlevel group (111.85 ± 2.79) vs.(108.88 ± 2.0),(101.08 ± 4.44) vs.(98.88 ± 2.0) P < 0.01.So were MDI and PDI in high-level group of colostrum compared with those in low-level group (111.71 ±3.07) vs.(108.81 ± 1.56),P < 0.01 ; (101.29 ± 4.23) vs.(98.56 ± 1.79),P < 0.05.The analysis on correlation between the levels of maternal-neonatal body fluids

  12. Cell patterning on polylactic acid through surface-tethered oligonucleotides.

    Science.gov (United States)

    Matsui, Toshiki; Arima, Yusuke; Takemoto, Naohiro; Iwata, Hiroo

    2015-02-01

    Polylactic acid (PLA) is a candidate material to prepare scaffolds for 3-D tissue regeneration. However, cells do not adhere or proliferate well on the surface of PLA because it is hydrophobic. We report a simple and rapid method for inducing cell adhesion to PLA through DNA hybridization. Single-stranded DNA (ssDNA) conjugated to poly(ethylene glycol) (PEG) and to a terminal phospholipid (ssDNA-PEG-lipid) was used for cell surface modification. Through DNA hybridization, modified cells were able to attach to PLA surfaces modified with complementary sequence (ssDNA'). Different cell types can be attached to PLA fibers and films in a spatially controlled manner by using ssDNAs with different sequences. In addition, they proliferate well in a culture medium supplemented with fetal bovine serum. The coexisting modes of cell adhesion through DNA hybridization and natural cytoskeletal adhesion machinery revealed no serious effects on cell growth. The combination of a 3-D scaffold made of PLA and cell immobilization on the PLA scaffold through DNA hybridization will be useful for the preparation of 3-D tissue and organs.

  13. Effects of elaidic acid, a predominant industrial trans fatty acid, on bacterial growth and cell surface hydrophobicity of lactobacilli.

    Science.gov (United States)

    Wu, Qinglong; Shah, Nagendra P

    2014-12-01

    The consumption of trans fatty acids (TFAs) increases the risk of cardiovascular diseases and coronary heart disease in human, and there are no effective ways to remove TFAs after consumption. The aim of this study was to investigate the effects of elaidic acid on bacterial growth, cell surface hydrophobicity of lactobacilli, and metabolism of elaidic acid by lactobacilli. Lactobacilli were inoculated in MRS broth containing 0, 100, 200, and 500 mg/L of elaidic acid. Viable cell counts of lactobacilli were enumerated, concentrations of elaidic acid were determined, and cell surface hydrophobicity of lactobacilli was measured. The results showed that the growth of lactobacilli was significantly inhibited by 500 mg/L of elaidic acid, however, a cell count of 8.50 log10 CFU/mL was still reached for tested lactobacilli after 24-h incubation. In particular, a reduction of elaidic acid was found for tested lactobacilli after 24-h incubation as compared to its initial concentration of 200 mg/L. However, cell surface hydrophobicity showed no correlations with the metabolism of elaidic acid by lactobacilli. Moreover, elaidic acid was able to influence cell surface hydrophobicity, and the decrease in hydrophobicity was more obvious in Lactobacillus paracasei and Lactobacillus casei compared with that in other tested lactobacilli. This study suggests that elaidic acid could change physiochemical surface properties of lactobacilli and the lactobacilli have the potential to reduce TFAs.

  14. Stereochemistry of amino acids in surface samples of a marine sediment

    Science.gov (United States)

    Pollock, G. E.; Kvenvolden, K. A.

    1978-01-01

    In two surface samples of marine sediment, the percentages of D-alanine and D-aspartic acid are significantly higher than the other D-amino acids and are similar to the range found in soils. The percentage of D-glutamic acid is also higher than the other amino acids but less than D-alanine and D-aspartic acid. These D-amino acids may come mainly from bacteria.

  15. Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane.

    Science.gov (United States)

    Doig, Michael; Warrens, Chris P; Camp, Philip J

    2014-01-14

    The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated by squalane are examined using large-scale molecular dynamics simulations. The structures of stearic acid and oleic acid films under static and shear conditions, and at various surface coverages, are described in detail, and the effects of unsaturation in the tail group are highlighted. At high surface coverage, the measured properties of stearic acid and oleic acid films are seen to be very similar. At low and intermediate surface coverages, the presence of a double bond, as in oleic acid, is seen to give rise to less penetration of lubricant in to the surfactant film and less layering of the lubricant near to the film. The kinetic friction coefficient is measured as a function of shear rate within the hydrodynamic (high shear rate) lubrication regime. Lubricant penetration and layering are observed to be correlated with friction coefficient. The friction coefficient with oleic acid depends only weakly on surface coverage, while stearic acid admits more lubricant penetration, and its friction coefficient increases significantly with decreasing surface coverage. Connections between film structure and friction are discussed.

  16. Surface effects in the esterification of 9-pyrenebutyric acid within a glass micro reactor

    NARCIS (Netherlands)

    Brivio, M.; Oosterbroek, R.E.; Verboom, Willem; Goedbloed, M.H.; van den Berg, Albert; Reinhoudt, David

    2003-01-01

    Surface phenomena are an important contribution to the chip effect, leading to higher yields and shorter reaction times, as demonstrated for the acid-catalysed esterification of 9-pyrenebutyric acid within a glass fabricated micro reactor.

  17. Staphylococcus aureus immunodominant surface antigen B is a cell-surface associated nucleic acid binding protein

    Directory of Open Access Journals (Sweden)

    Cerca Nuno

    2009-03-01

    Full Text Available Abstract Background Staphylococcus aureus immunodominant surface antigen B (IsaB elicits an immune response during septicemia and is generally classified as a virulence factor, but its biological function remains completely undefined. In an attempt to identify staphylococcal RNA-binding proteins, we designed an RNA Affinity Chromatography assay and subsequently isolated IsaB. Results Western analysis indicated that IsaB was both secreted and cell-surface associated. Gel Shift analysis confirmed the RNA binding activity but revealed that IsaB bound to any nucleic acid without sequence specificity. IsaB exhibited the highest affinity for double-stranded DNA followed by single-stranded DNA and RNA. Because extracellular DNA has been shown to play a role in biofilm formation, we investigated the biofilm-forming capacity of an isogenic isaB deletion mutant but we found that IsaB did not contribute to biofilm formation under any conditions tested. Conclusion IsaB is an extracellular nucleic acid binding protein, with little to no sequence specificity, but its role in virulence remains unclear.

  18. The expression of sialic acid-binding immunoglobulin-like lectin 1 on peripheral mononuclear cells in patients with coronary heart disease and its clinical significance%唾液酸结合免疫球蛋白样凝集素1在冠状动脉粥样硬化性心脏病患者外周血单个核细胞的表达及临床意义

    Institute of Scientific and Technical Information of China (English)

    熊怡淞; 荣光华; 仲人前; 周运恒; 吴炜霖; 张玲珍; 梁艳; 杨再兴; 耿红莲; 王皓; 王爱华

    2009-01-01

    目的 观察唾液酸结合免疫球蛋白样凝集素1(sialic acid-binding immunoglobulin-likelectin 1,Siglec-1,也称CD169)在冠状动脉粥样硬化性心脏病(CHD)患者外周血淋巴细胞、单核细胞和中性粒细胞上的表达水平,并探讨其与冠状动脉粥样硬化发生发展的关系.方法 流式细胞术检测57例CHD患者及38名健康对照者外周血CD14CD169双阳性细胞的表达率;生化常规测定所有入选者血脂水平;实时荧光相对定量逆转录(FQ-RT)-PCR方法检测入选对象外周血单个核细胞(PBMCs)中CD169 mRNA的含量.结果 流式细胞仪检测发现,CD169在健康对照组及CHD组淋巴细胞和中性粒细胞上均无表达;CHD组单核细胞CD14CD169双阳性率为(12.7±2.4)%,显著高于健康对照组[(1.0±0.3)%,t=23.2,P0.05]和mRNA平均拷贝数(分别为健康对照组的3.64和2.79倍,t=0.98,P>0.05)差异均无统计学意义.结论 CD169组成性表达于特定组织巨噬细胞上,健康人外周血单核细胞上并不表达,单核巨噬细胞受到炎症刺激时,CD169表达迅速上调.CD169蛋白及mRNA含量在CHD患者外周血单核细胞上表达显著升高,CHD患者外周血单核细胞已发生巨噬细胞化,单核巨噬细胞介导的免疫炎症反应在CHD发生发展过程中起重要作用.%Objective To investigate the expression of sialic acid-binding immunoglobulin-like lectin-one (Siglec-1, also called CD169) in lymphocytes, monocytes and neutrophils in peripheral blood in patients with coronary heart disease(CHD), and explore the relationship between Siglec-1 expression and atheresclerosis. Methods CD145 CD169 positive cell proportion and CD169 mRNA levels were respectively measured by flow cytometry and real-time quantitative reverse transcription-polymerase chain reaction (FQ-RT-PCR) in 57 CHD patients and 38 healthy controls. And the levels of serum hpids were determined by automatic biochemistry analyzer. Results The flow cytometry analysis showed that CD169

  19. Evolution of the graphite surface in phosphoric acid: an AFM and Raman study

    Science.gov (United States)

    Brambilla, Luigi; Bussetti, Gianlorenzo; Tommasini, Matteo; Li Bassi, Andrea; Casari, Carlo Spartaco; Passoni, Matteo; Ciccacci, Franco; Duò, Lamberto; Castiglioni, Chiara

    2016-01-01

    Summary Phosphoric acid is an inorganic acid used for producing graphene sheets by delaminating graphite in (electro-)chemical baths. The observed phenomenology during the electrochemical treatment in phosphoric acid solution is partially different from other acidic solutions, such as sulfuric and perchloric acid solutions, where the graphite surface mainly forms blisters. In fact, the graphite surface is covered by a thin layer of modified (oxidized) material that can be observed when an electrochemical potential is swept in the anodic current regime. We characterize this particular surface evolution by means of a combined electrochemical, atomic force microscopy and Raman spectroscopy investigation.

  20. N-Acetylneuraminic acid storage disease.

    Science.gov (United States)

    Baumkötter, J; Cantz, M; Mendla, K; Baumann, W; Friebolin, H; Gehler, J; Spranger, J

    1985-01-01

    Increased amounts of free sialic acid were found in body fluids, leukocytes, cultured fibroblasts, and liver tissue of a four-year-old boy with mental retardation, ataxia, and clinical and radiologic findings of a mild mucopolysaccharidosis. A diagnosis of Salla disease was made though in contrast to earlier reports, recurrent upper respiratory infections and hepatosplenomegaly were present already in infancy, and skeletal abnormalities of dysostosis multiplex were found in early childhood. Free sialic acid in the urine was identified as N-acetylneuraminic acid by 1H-NMR spectroscopy. Sialidase activities were normal. Increased amounts of bound sialic acid were found in liver and cultured fibroblasts and were attributed to an intracellular inhibition of sialyloligosaccharide-degrading neuraminidase by excessive amounts of free neuraminic acid. The molecular basis of N-acetylneuraminic acid storage disease is unknown but may be related to a defective transport mechanism preventing neuraminic acid from leaving the lysosomal compartment.

  1. Surface Activity of Humic Acids Depending on Their Origin and Humification Degree

    Directory of Open Access Journals (Sweden)

    Klaviņš Māris

    2014-07-01

    Full Text Available Humic substances are able to reduce the surface tension of their solutions and thus can act as surface-active substances in the natural environment, which may have industrial application. The ability to influence the surface tension of humic acid solutions depends on the origin of the humic acids. The objective of this study was comparison of the ability of humic acids of different origin (soil, water, peat, lignite etc. to influence the surface tension of their solutions, and identification of the structural characteristics of peat humic acids that determine their surfactant properties. Industrially produced humic materials demonstrated no or insignificant impact on the surface tension of their solutions. However, humic acids isolated from peat had significant impact of the surface tension of their solutions, acting as weak surfactants. The surface tension of humic acid solutions decreased with increasing concentration, and depended on solution pH. Using a well-characterised bog profile, the ability to influence the surface tension of peat humic acids was shown to depend on age and humification degree. With increase of the humification degree and age, molecular complexity of humic acids and their ability to influence surface tension decreased; but nevertheless, the impact of the biological precursor (peat-forming bryophytes and plants could be identified.

  2. Influenza C virus uses 9-O-acetyl-N-acetylneuraminic acid as a high affinity receptor determinant for attachment to cells.

    Science.gov (United States)

    Rogers, G N; Herrler, G; Paulson, J C; Klenk, H D

    1986-05-05

    Identification of the receptor-destroying enzyme of influenza C virus as a specific neuraminate O-acetylesterase has suggested that 9-O-acetyl-N-acetylneuraminic acid is an essential component of the cell surface receptor of influenza C virus (Herrler, G., Rott, R., Klenk, H.-D., Muller, H.-P., Shukla, A. K., and Schauer, R. (1985) EMBO (Eur. Mol. Biol. Organ.) J. 4, 1503-1506). In this report, three common sialic acids, N-acetylneuraminic acid (NeuAc), N-glycollylneuraminic acid (NeuGc), and 9-O-acetyl-N-acetylneuraminic acid (9-O-Ac-NeuAc) were compared for their ability to mediate attachment of influenza A, B, and C viruses to cells. Human asialoerythrocytes were resialylated to contain the three sialic acids in defined sequence on glycoprotein carbohydrate groups using purified sialyltransferases and corresponding CMP-sialic acid donor substrates. While influenza C virus failed to agglutinate native cells or resialylated cells containing NeuAc and NeuGc, resialylated cells containing 9-O-Ac-NeuAc in three different sialyloligosaccharide sequences were agglutinated in high titer. In contrast, most representative influenza A and B viruses examined preferentially agglutinated cells containing NeuAc and NeuGc and failed to agglutinate cells containing 9-O-Ac-NeuAc. Cells containing 9-O-Ac-NeuAc were sensitive to the action of influenza C virus neuraminate O-acetylesterase which converts 9-O-Ac-NeuAc to NeuAc. This treatment abolished agglutination by influenza C while making the cells agglutinable by several influenza A and B viruses. Finally, the ability of influenza C virus to agglutinate the erythrocytes of various species correlated with the presence of 9-O-Ac-NeuAc. The results provide direct evidence that influenza C virus utilizes 9-O-acetyl-N-acetylneuraminic acid as the primary receptor determinant for attachment to cell surface receptors.

  3. Surface Energy and Work Function Control of AlOx/Al Surfaces by Fluorinated Benzylphosphonic Acids.

    Science.gov (United States)

    Abraham, Ffion; Ford, William E; Scholz, Frank; Nelles, Gabriele; Sandford, Graham; von Wrochem, Florian

    2016-05-11

    The performance of organic electronic devices can be significantly improved by modifying metal electrodes with organic monolayers, which alter the physical and chemical nature of the interface between conductor and semiconductor. In this paper we examine a series of 12 phosphonic acid compounds deposited on the native oxide layer of aluminum (AlOx/Al), an electrode material with widespread applications in organic electronics. This series includes dodecylphosphonic acid as a reference and 11 benzylphosphonic acids, seven of which are fluorinated, including five newly synthesized derivatives. The monolayers are experimentally characterized by contact angle goniometry and by X-ray photoemission spectroscopy (XPS), and work function data obtained by low-intensity XPS are correlated with molecular dipoles obtained from DFT calculations. We find that monolayers are formed with molecular areas ranging from 17.7 to 42.9 Å(2)/molecule, and, by the choice of appropriate terminal groups, the surface energy can be tuned from 23.5 mJ/m(2) to 70.5 mJ/m(2). Depending on the number and position of fluorine substituents on the aromatic rings, a variation in the work function of AlOx/Al substrates over a range of 0.91 eV is achieved, and a renormalization procedure based on molecular density yields a surprising agreement of work function changes with interface dipoles as expected from Helmholtz' equation. The ability to adjust energetics and adhesion at organic semiconductor/AlOx interfaces has immediate applications in devices such as OLEDs, OTFTs, organic solar cells, and printed organic circuits.

  4. Adhesion of smooth and rough phenotypes of Flavobacterium psychrophilum to polystyrene surfaces.

    Science.gov (United States)

    Högfors-Rönnholm, E; Norrgård, J; Wiklund, T

    2015-05-01

    Phenotypic smooth cells of the fish pathogenic bacterium Flavobacterium psychrophilum have previously been reported to be more adhesive to polystyrene surfaces than corresponding rough cells. In this study, the adhesion ability of smooth and rough cells of F. psychrophilum to polystyrene surfaces was investigated in detail with a crystal violet staining method. By treating both polystyrene surfaces with fish mucus and carbohydrates and the bacterial cells with carbohydrates, the involvement of lectins in the adhesion process was investigated. Smooth cells showed significantly higher adhesion ability to untreated polystyrene surfaces compared with corresponding rough cells and increasing water hardness had an inhibitory effect on the adhesion. Treatment of polystyrene surfaces with D-glucose, D-galactose and fish mucus increased the adhesion ability of smooth cells to polystyrene. Furthermore, treatment of the smooth cells with D-glucose, D-galactose and sialic acid decreased the adhesion ability of the cells, indicating that the adhesion is likely mediated by complementary lectins on the surface of the cells. Sodium (meta)periodate treatment of smooth cells also decreased the adhesion ability to polystyrene, suggesting that the lectins, such as the dominating sialic acid-binding lectin, are probably localized in the extracellular polysaccharides surrounding the cells.

  5. Daytime of Sampling, Tooth-Brushing and Ascorbic Acid Influence Salivary Thiobarbituric Acid Reacting Substances – A Potential Clinical Marker of Gingival Status

    Directory of Open Access Journals (Sweden)

    Július Hodosy

    2005-01-01

    Sialic acid content of saliva is not influenced significantly by any of the investigated factors. Conclusion. TBARS levels in saliva are affected by daytime of sampling, tooth-brushing and ascorbic acid pre-treatment. These results must be considered in clinical research using salivary TBARS levels. Sialic acid seems not to be a major component of TBARS in saliva. Further studies should clarify the molecular compounds of salivary TBARS and uncover the role of oral microbial factors.

  6. [Formation of organic acids by fungi isolated from the surface of stone monuments].

    Science.gov (United States)

    Sazanova, K V; Shchiparev, S M; Vlasov, D Iu

    2014-01-01

    Capacity of the fungi isolated from the surface of stone monuments for acid formation was studied in cultures under various carbon sources and cultivation conditions. The composition of organic nutrients was adjusted according to the results of investigation of the surface layers from the monuments in urban environment. The primary soil formed at the surface of the stone monuments under urban conditions was shown to contain a variety of carbon and nitrogen sources and is a rich substrate for fungal growth. Oxalic acid was produced by fungi grown on media with various concentrations of sugars, sugar alcohols, and organic acids. Malic, citric, fumaric, and succinic acids were identified only at elevated carbohydrate concentrations, mostly in liquid cultures. Oxalic acid was the dominant among the acids produced by Aspergillus niger at all experimental setups. Unlike A. niger, the relative content of oxalic acid produced by Penicillium citrinum decreased at high carbohydrate concentrations.

  7. Self-assembled Monolayers of n-Hexadecanoic Acid and α-Hydroxyl n-Hexadecanoic Acid on Titanium Surfaces

    Institute of Scientific and Technical Information of China (English)

    CHEN,Hai-Gang(陈海刚); WU,Xue-Dong(乌学东); YU,Qin-Qin(虞勤琴); YANG,Sheng-Rong(杨生荣); WANG,Da-Pu(王大璞); SHEN,Wen-Zhong(沈文忠)

    2002-01-01

    n-Hexadecanoic acid (HA) and a.hydroxyl n-hexadecanoic acid ( HHA ) are shown to spontaneously assemble on Si-supported titanium surfaces. Contact angle measurements, reflection absorbance IR, AFM and XPS characterizatiions are performed to examine the physical and chenical states of attached monolayers. The results show that the two amphiphiles tend to form disordered monolayers on titanium surfaces. The HHA headgroups are believed to form polydentate coordination with Ti, which is more chemically stable than the bidentate coordination of HA. All the facts of characterization indicate that HHA monolayer has more surface coverage than HA monolayer.

  8. Cesium Salts of Phosphotungstic Acid: Comparison of Surface ...

    African Journals Online (AJOL)

    NICO

    the residual protons are more acidic than the homogeneous acid catalysts (e.g. ... area, amount of water of crystallization and thermal stability are sensitive to the ... 100 °C for reuse. The filtrate was ... RESEARCH ARTICLE. E. Rafiee & M.

  9. Use of organic acids for prevention and removal of Bacillus subtilis biofilms on food contact surfaces.

    Science.gov (United States)

    Akbas, Meltem Yesilcimen; Cag, Seyda

    2016-10-01

    The efficacies of organic acid (citric, malic, and gallic acids) treatments at 1% and 2% concentrations on prevention and removal of Bacillus subtilis biofilms were investigated in this study. The analyses were conducted on microtitration plates and stainless steel coupons. The biofilm removal activities of these organic acids were compared with chlorine on both surfaces. The results showed that citric acid treatments were as powerful as chlorine treatments for prevention and removal of biofilms. The antibiofilm effects of malic acid treatments were higher than gallic acid and less than citric acid treatment. When the antibiofilm effects of these acids and chlorine on the two surfaces were compared, the prevention and removal of biofilms were measured higher on microtitration plates than those on stainless steel coupons. Higher reductions were obtained by increasing concentrations of sanitizers on 24-hour biofilm with 20-minute sanitizer treatments for removal of biofilms.

  10. Local and global chirality at surfaces: succinic acid versus tartaric acid on Cu110.

    Science.gov (United States)

    Humblot, Vincent; Lorenzo, Maria Ortega; Baddeley, Christopher J; Haq, Sam; Raval, Rasmita

    2004-05-26

    A detailed comparison of tartaric acid (HOOC-CHOH-CHOH-COOH) and succinic acid (HOOC-CH(2)-CH(2)-COOH) molecules on a Cu(110) surface is presented with a view to elucidate how the two-dimensional chirality exhibited by such robust, chemisorbed systems is affected when both OH groups of the former molecule are replaced with H groups, a stereochemical change that leaves the metal-bonding functionalities of the molecule untouched but destroys both chiral centers. It is found that this change does not significantly affect the thermodynamically preferred chemical forms that are adopted, namely the doubly deprotonated bicarboxylate at low coverages (theta

  11. Adsorption behavior of antimony(III) oxyanions on magnetite surface in aqueous organic acid environment

    Science.gov (United States)

    Mittal, Vinit K.; Bera, Santanu; Narasimhan, S. V.; Velmurugan, S.

    2013-02-01

    Antimony(III) adsorption is observed on magnetite (Fe3O4) surface under acidic and reducing condition through surface hydroxyl (SOH) groups bonding on Fe3O4 surface. Desorption of adsorbed Sb(III) is observed from Fe3O4 surface along with iron release in organic acid at 85 °C after 5 h of experiment. Tartaric acid (TA) shows minimum Sb(III) adsorption on Fe3O4 among the organic acid studied. The reason is TA having two sets of adjacent functional groups viz. Odbnd Csbnd OH and Csbnd OH which are responsible for the formation of five-membered bidendate chelate with Sb(III). Other oxyanions, cations or complexing agents along with TA influences the Sb(III) adsorption on Fe3O4. The surface of magnetite is modified by the addition of fatty acids viz. Lauric acid, benzoic acid to bind the Ssbnd OH groups present on the surface. This results in delaying the process of adsorption without changing the quantity of saturation adsorption of Sb(III) on Fe3O4 surface.

  12. Surface Tension of Acid Solutions: Fluctuations beyond the Non-linear Poisson-Boltzmann Theory

    CERN Document Server

    Markovich, Tomer; Podgornik, Rudi

    2016-01-01

    We extend our previous study of surface tension of ionic solutions and apply it to the case of acids (and salts) with strong ion-surface interactions. These ion-surface interactions yield a non-linear boundary condition with an effective surface charge due to adsorption of ions from the bulk onto the interface. The calculation is done using the loop-expansion technique, where the zero-loop (mean field) corresponds of the non-linear Poisson-Boltzmann equation. The surface tension is obtained analytically to one-loop order, where the mean-field contribution is a modification of the Poisson-Boltzmann surface tension, and the one-loop contribution gives a generalization of the Onsager-Samaras result. Our theory fits well a wide range of different acids and salts, and is in accord with the reverse Hofmeister series for acids.

  13. Chemical characteristics of fulvic acids from Arctic surface waters: Microbial contributions and photochemical transformations

    Science.gov (United States)

    Cory, Rose M.; McKnight, Diane M.; Chin, Yu-Ping; Miller, Penney; Jaros, Chris L.

    2007-12-01

    Dissolved organic matter (DOM) originating from the extensive Arctic tundra is an important source of organic material to the Arctic Ocean. Chemical characteristics of whole water dissolved organic matter (DOM) and the fulvic acid fraction of DOM were studied from nine surface waters in the Arctic region of Alaska to gain insight into the extent of microbial and photochemical transformation of this DOM. All the fulvic acids had a strong terrestrial/higher plant signature, with uniformly depleted δ13C values of -28‰, and low fluorescence indices around 1.3. Several of the measured chemical characteristics of the Arctic fulvic acids were related to water residence time, a measure of environmental exposure to sunlight and microbial activity. For example, fulvic acids from Arctic streams had higher aromatic contents, higher specific absorbance values, lower nitrogen content, lower amino acid-like fluorescence and were more depleted in δ15N relative to fulvic acids isolated from lake and coastal surface waters. The differences in the nitrogen signature between the lake and coastal fulvic acids compared to the stream fulvic acids indicated that microbial contributions to the fulvic acid pool increased with increasing water residence time. The photo-lability of the fulvic acids was positively correlated with water residence time, suggesting that the fulvic acids isolated from source waters with larger water residence times (i.e., lakes and coastal waters) have experienced greater photochemical degradation than the stream fulvic acids. In addition, many of the initial differences in fulvic acid chemical characteristics across the gradient of water residence times were consistent with changes observed in fulvic acid photolysis experiments. Taken together, results from this study suggest that photochemical processes predominantly control the chemical character of fulvic acids in Arctic surface waters. Our findings show that hydrologic transport in addition to

  14. Spectroscopic study on variations in illite surface properties after acid-base titration

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    FT-IR, Raman microscopy, XRD, 29 Si and 27 Al MAS NMR, were used to investigate changes in surface properties of a natural illitesample after acid-base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al-Si complexes, preferable to Al(OH)3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si-O and Al-O bonds diminished as a result of treatment withacid, then increased after hydroxide back titration. The varied ratio of signal intensity between Ⅳ Al and Ⅵ At species in 27 Al MAS NMRspectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure ofillite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illitesurfaces and acid-leaching silicic acid and aluminum ions should be considered in the model description of surface acid-base properties of theaqueous illite.

  15. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    Energy Technology Data Exchange (ETDEWEB)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  16. Effect of acidic solutions on the surface degradation of a micro-hybrid composite resin.

    Science.gov (United States)

    Münchow, Eliseu A; Ferreira, Ana Cláudia A; Machado, Raissa M M; Ramos, Tatiana S; Rodrigues-Junior, Sinval A; Zanchi, Cesar H

    2014-01-01

    Composite resins may undergo wear by the action of chemical substances (e.g., saliva, alcohol, bacterial acids) of the oral environment, which may affect the material's structure and surface properties. This study evaluated the effect of acidic substances on the surface properties of a micro-hybrid composite resin (Filtek Z-250). Eighty specimens were prepared, and baseline hardness and surface roughness (KMN0 and Ra0, respectively) were measured. The specimens were subjected to sorption (SO) and solubility (SL) tests according to ISO 4049:2009, but using different storage solutions: deionized water; 75/25 vol% ethanol/water solution; lactic acid; propionic acid; and acetic acid. The acids were used in two concentrations: PA and 0.02 N. pH was measured for all solutions and final hardness (KMN1) and surface roughness (Ra1) were measured. Data were analyzed with paired t-tests and one-way ANOVA and Tukey's test (a=5%). All solutions decreased hardness and increased the Ra values, except for the specimens stored in water and 0.02 N lactic acid, which maintained the hardness. All solutions produced similar SO and SL phenomena, except for the 0.02 N lactic acid, which caused lower solubility than the other solutions. Ethanol showed the highest pH (6.6) and the 0.02 N lactic acid the lowest one (2.5). The solutions affected negatively the surface properties of the composite resin; in addition, an acidic pH did not seem to be a significant factor that intensifies the surface degradation phenomena.

  17. Library of Antifouling Surfaces Derived From Natural Amino Acids by Click Reaction.

    Science.gov (United States)

    Xu, Chen; Hu, Xin; Wang, Jie; Zhang, Ye-Min; Liu, Xiao-Jiu; Xie, Bin-Bin; Yao, Chen; Li, Yi; Li, Xin-Song

    2015-08-12

    Biofouling is of great concern in numerous applications ranging from ophthalmological implants to catheters, and from bioseparation to biosensors. In this report, a general and facile strategy to combat surface fouling is developed by grafting of amino acids onto polymer substrates to form zwitterionic structure through amino groups induced epoxy ring opening click reaction. First of all, a library of poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) hydrogels with zwitterionic surfaces were prepared, resulting in the formation of pairs of carboxyl anions and protonated secondary amino cations. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the successful immobilization of amino acids on the hydrogel surfaces. After that, the contact angle and equilibrium water content of the modified hydrogels showed that the hydrogels exhibited improved hydrophilicity compared with the parent hydrogel. Furthermore, the protein deposition was evaluated by bicinchoninic acid assay using bovine serum albumin (BSA) and lysozyme as models. The results indicated that the performance of the hydrogels was determined by the nature of incorporated amino acid: the hydrogels incorporated with neutral amino acids had nonspecific antiadsorption capability to both BSA and lysozyme; the hydrogels incorporated with charged amino acids showed antiadsorption behaviors against protein with same charge and enhanced adsorption to the protein with opposite charge; the optimal antiadsorption performance was observed on the hydrogels incorporated with polar amino acids with a hydroxyl residual. The improvement of antiprotein fouling of the neutral amino acids grafted hydrogels can be ascribed to the formation of zwitterionic surfaces. Finally, a couple of soft contact lenses grafted with amino acids were fabricated having improved antifouling property and hydrophilicity. The result demonstrated the success of

  18. BIOPHYSICAL PROPERTIES OF NUCLEIC ACIDS AT SURFACES RELEVANT TO MICROARRAY PERFORMANCE.

    Science.gov (United States)

    Rao, Archana N; Grainger, David W

    2014-04-01

    Both clinical and analytical metrics produced by microarray-based assay technology have recognized problems in reproducibility, reliability and analytical sensitivity. These issues are often attributed to poor understanding and control of nucleic acid behaviors and properties at solid-liquid interfaces. Nucleic acid hybridization, central to DNA and RNA microarray formats, depends on the properties and behaviors of single strand (ss) nucleic acids (e.g., probe oligomeric DNA) bound to surfaces. ssDNA's persistence length, radius of gyration, electrostatics, conformations on different surfaces and under various assay conditions, its chain flexibility and curvature, charging effects in ionic solutions, and fluorescent labeling all influence its physical chemistry and hybridization under assay conditions. Nucleic acid (e.g., both RNA and DNA) target interactions with immobilized ssDNA strands are highly impacted by these biophysical states. Furthermore, the kinetics, thermodynamics, and enthalpic and entropic contributions to DNA hybridization reflect global probe/target structures and interaction dynamics. Here we review several biophysical issues relevant to oligomeric nucleic acid molecular behaviors at surfaces and their influences on duplex formation that influence microarray assay performance. Correlation of biophysical aspects of single and double-stranded nucleic acids with their complexes in bulk solution is common. Such analysis at surfaces is not commonly reported, despite its importance to microarray assays. We seek to provide further insight into nucleic acid-surface challenges facing microarray diagnostic formats that have hindered their clinical adoption and compromise their research quality and value as genomics tools.

  19. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

    2002-01-01

    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores t

  20. Natural and pyrogenic humic acids at goethite and natural oxide surfaces interacting with phosphate

    NARCIS (Netherlands)

    Hiemstra, T.; Mia, S.; Duhaut, P.B.; Molleman, B.

    2013-01-01

    Fulvic and humic acids have a large variability in binding to metal (hydr) oxide surfaces and interact differently with oxyanions, as examined here experimentally. Pyrogenic humic acid has been included in our study since it will be released to the environment in the case of large-scale application

  1. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

    2002-01-01

    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores t

  2. Production of N-acetyl-D-neuraminic acid using two sequential enzymes overexpressed as double-tagged fusion proteins

    Directory of Open Access Journals (Sweden)

    Cheng Chung-Hsien

    2009-07-01

    Full Text Available Abstract Background Two sequential enzymes in the production of sialic acids, N-acetyl-D-glucosamine 2-epimerase (GlcNAc 2-epimerase and N-acetyl-D-neuraminic acid aldolase (Neu5Ac aldolase, were overexpressed as double-tagged gene fusions. Both were tagged with glutathione S-transferase (GST at the N-terminus, but at the C-terminus, one was tagged with five contiguous aspartate residues (5D, and the other with five contiguous arginine residues (5R. Results Both fusion proteins were overexpressed in Escherichia coli and retained enzymatic activity. The fusions were designed so their surfaces were charged under enzyme reaction conditions, which allowed isolation and immobilization in a single step, through a simple capture with either an anionic or a cationic exchanger (Sepharose Q or Sepharose SP that electrostatically bound the 5D or 5R tag. The introduction of double tags only marginally altered the affinity of the enzymes for their substrates, and the double-tagged proteins were enzymatically active in both soluble and immobilized forms. Combined use of the fusion proteins led to the production of N-acetyl-D-neuraminic acid (Neu5Ac from N-acetyl-D-glucosamine (GlcNAc. Conclusion Double-tagged gene fusions were overexpressed to yield two enzymes that perform sequential steps in sialic acid synthesis. The proteins were easily immobilized via ionic tags onto ionic exchange resins and could thus be purified by direct capture from crude protein extracts. The immobilized, double-tagged proteins were effective for one-pot enzymatic production of sialic acid.

  3. Laser restoring the glass surface treated with acid-based paint

    Science.gov (United States)

    Strusevich, Anastasia V.; Poltaev, Yuriy A.; Sinev, Dmitrii A.

    2013-11-01

    The modern city facilities are often being attacked by graffiti artists, and increasingly vandals leave "tags" using paints, which compound based on acids, hydrofluoric or acetic commonly. These paints not only ink the surface, but also increase the surface roughness, and such impact can not be corrected by conventional cleaning. Thus, it was requested to develop technology that would not only clean the surface, but also to restore its structure by smoothing out irregularities and roughness formed after exposure in acid. In this work we investigated the effect of restoring the surface of the glass, spoiled by acid-based paint and then treated with CO2-laser. During the experiments, it was found that it is real to create the single-step laser surface restoring technology.

  4. Surface acidity and solid-state compatibility of excipients with an acid-sensitive API: case study of atorvastatin calcium.

    Science.gov (United States)

    Govindarajan, Ramprakash; Landis, Margaret; Hancock, Bruno; Gatlin, Larry A; Suryanarayanan, Raj; Shalaev, Evgenyi Y

    2015-04-01

    The objectives of this study were to measure the apparent surface acidity of common excipients and to correlate the acidity with the chemical stability of an acid-sensitive active pharmaceutical ingredient (API) in binary API-excipient powder mixtures. The acidity of 26 solid excipients was determined by two methods, (i) by measuring the pH of their suspensions or solutions and (ii) the pH equivalent (pHeq) measured via ionization of probe molecules deposited on the surface of the excipients. The chemical stability of an API, atorvastatin calcium (AC), in mixtures with the excipients was evaluated by monitoring the appearance of an acid-induced degradant, atorvastatin lactone, under accelerated storage conditions. The extent of lactone formation in AC-excipient mixtures was presented as a function of either solution/suspension pH or pHeq. No lactone formation was observed in mixtures with excipients having pHeq > 6, while the lactone levels were pronounced (> 0.6% after 6 weeks at 50°C/20% RH) with excipients exhibiting pHeq 6, 3-6, and API, were identified based on pHeq measurements. The incompatibility prediction was confirmed in the chemical stability tests using AC as an example of an acid-sensitive API.

  5. Heterogeneous Reactions of Acetic Acid with Oxide Surfaces: Effects of Mineralogy and Relative Humidity.

    Science.gov (United States)

    Tang, Mingjin; Larish, Whitney A; Fang, Yuan; Gankanda, Aruni; Grassian, Vicki H

    2016-07-21

    We have investigated the heterogeneous uptake of gaseous acetic acid on different oxides including γ-Al2O3, SiO2, and CaO under a range of relative humidity conditions. Under dry conditions, the uptake of acetic acid leads to the formation of both acetate and molecularly adsorbed acetic acid on γ-Al2O3 and CaO and only molecularly adsorbed acetic acid on SiO2. More importantly, under the conditions of this study, dimers are the major form for molecularly adsorbed acetic acid on all three particle surfaces investigated, even at low acetic acid pressures under which monomers are the dominant species in the gas phase. We have also determined saturation surface coverages for acetic acid adsorption on these three oxides under dry conditions as well as Langmuir adsorption constants in some cases. Kinetic analysis shows that the reaction rate of acetic acid increases by a factor of 3-5 for γ-Al2O3 when relative humidity increases from 0% to 15%, whereas for SiO2 particles, acetic acid and water are found to compete for surface adsorption sites.

  6. The simple detection of neuraminic acid-containing urinary oligosaccharides in patients with glycoprotein storage diseases.

    Science.gov (United States)

    Sewell, A C

    1983-01-01

    Urine samples from patients with different types of glycoprotein storage disease were chromatographed by gel filtration and the fractions analysed for sialic acid. Patients with mucolipidoses I and II excreted the largest amounts of bound sialic acid. One patient with GM1 gangliosidosis showed an abnormal level of sialyloligosaccharide excretion. Other patients showed normal results. With the present method mucolipidoses I and II, together with GM1 gangliosidosis, are readily distinguished from other possible oligosaccharidurias.

  7. Electrochemical dissolution of surface alloys in acids: Thermodynamic trends from first-principles calculations

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2007-01-01

    A simple procedure is introduced to use periodic Density Functional Theory calculations to estimate trends in the thermodynamics of surface alloy dissolution in acidic media. With this approach, the dissolution potentials for solute metal atoms embedded in the surface layer of various host metals...

  8. Direct monophasic replacement of fatty acid by DMSA on SPION surface

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, M. [Department of Physics, Tezpur University (Central University), Tezpur 784028 (India); Deb, P., E-mail: pdeb@tezu.ernet.in [Department of Physics, Tezpur University (Central University), Tezpur 784028 (India); Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Duesseldorf (Germany); Vasan, G.; Keil, P.; Kostka, A.; Erbe, A. [Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Duesseldorf (Germany)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Monophasic replacement of fatty acid coating. Black-Right-Pointing-Pointer Ultrastable dispersion of hydrophilic SPION in a wide pH range. Black-Right-Pointing-Pointer Unaltered microstructure and property on surface modification. - Abstract: Tailoring the surface and understanding the surface characteristics is necessary for biomedical applications of superparamagnetic nanoparticles. In this paper, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared by thermal decomposition of iron nitrate in presence of stearic acid as surfactant. Due to the multilayer organization of surfactant molecules over the nanoparticle surface, the surface potential can be tuned by pH changes and hence the nanoparticles can be made dispersible in nonpolar as well as in polar solvents. We have presented a simple, facile procedure for controlled replacement of stearic acid from maghemite surface and subsequent derivatization by biocompatible dimercaptosuccinic acid (DMSA) to obtain ultrastable hydrophilic nanoparticles with unaltered morphology, phase and properties. The surface chemistry of the functionalized SPIONs was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) revealing the presence of bound and unbound thiol groups and disulfides, leading to its prolonged stability in aqueous medium. The consequence of spatially selective functionalization on the stability and solubility of surface hydrophilic SPION has also been realized.

  9. Radiation-induced reactions of amino acids adsorbed on solid surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Esquivel Kranksith, L.; Negron-Mendoza, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, UNAM. Cd. Universitaria, A.P. 70-543, 04510 Mexico D.F. (Mexico); Mosqueira, F.G. [Direcion General de Divulgacion de la Ciencia, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, AP. 70-487 Mexico D.F. (Mexico); Ramos-Bernal, Sergio, E-mail: ramos@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, UNAM. Cd. Universitaria, A.P. 70-543, 04510 Mexico D.F. (Mexico)

    2010-07-21

    The purpose of this work is to study the adsorption of compounds such as amino acids on clays and carbon nanotubes (CNTs) as a possible phase in the chemical evolution that may have occurred on the primitive Earth or in extraterrestrial environments. We further study the behavior of amino acids adsorbed on these solid surfaces at different conditions of pH and levels of irradiation, simulating a high-radiation field at early Earth conditions. The relevance of this work is to explain the possible contribution of solids (clays and CNTs) as promoters of polymerization and as shields for the adsorbed organic compounds against external sources of energy. To this end, tryptophan, aspartic acid, and glutamic acid were adsorbed on fixed amounts of solid surfaces and were irradiated by a {sup 60}Co source for different periods of time at fixed dose rates. After irradiation, the amino acids were extracted from the solid and analyzed with UV and IR spectroscopes and high-performance liquid chromatography. The most efficient surface for adsorption of amino acids was clay, followed by CNTs. Studies of the gamma irradiation of amino acids adsorbed on clay (in the solid phase) show a low yield of recovery of the amino acid.

  10. Asymmetric Anion-π Catalysis: Enamine Addition to Nitroolefins on π-Acidic Surfaces.

    Science.gov (United States)

    Zhao, Yingjie; Cotelle, Yoann; Avestro, Alyssa-Jennifer; Sakai, Naomi; Matile, Stefan

    2015-09-16

    Here we provide experimental evidence for anion-π catalysis of enamine chemistry and for asymmetric anion-π catalysis. A proline for enamine formation on one side and a glutamic acid for nitronate protonation on the other side are placed to make the enamine addition to nitroolefins occur on the aromatic surface of π-acidic naphthalenediimides. With increasing π acidity of the formally trifunctional catalysts, rate and enantioselectivity of the reaction increase. Mismatched and more flexible controls reveal that the importance of rigidified, precisely sculpted architectures increases with increasing π acidity as well. The absolute configuration of stereogenic sulfoxide acceptors at the edge of the π-acidic surface has a profound influence on asymmetric anion-π catalysis and, if perfectly matched, affords the highest enantio- and diastereoselectivity.

  11. Acid base properties of cyanobacterial surfaces I: Influences of growth phase and nitrogen metabolism on cell surface reactivity

    Science.gov (United States)

    Lalonde, S. V.; Smith, D. S.; Owttrim, G. W.; Konhauser, K. O.

    2008-03-01

    Significant efforts have been made to elucidate the chemical properties of bacterial surfaces for the purposes of refining surface complexation models that can account for their metal sorptive behavior under diverse conditions. However, the influence of culturing conditions on surface chemical parameters that are modeled from the potentiometric titration of bacterial surfaces has received little regard. While culture age and metabolic pathway have been considered as factors potentially influencing cell surface reactivity, statistical treatments have been incomplete and variability has remained unconfirmed. In this study, we employ potentiometric titrations to evaluate variations in bacterial surface ligand distributions using live cells of the sheathless cyanobacterium Anabaena sp. strain PCC 7120, grown under a variety of batch culture conditions. We evaluate the ability for a single set of modeled parameters, describing acid-base surface properties averaged over all culture conditions tested, to accurately account for the ligand distributions modeled for each individual culture condition. In addition to considering growth phase, we assess the role of the various assimilatory nitrogen metabolisms available to this organism as potential determinants of surface reactivity. We observe statistically significant variability in site distribution between the majority of conditions assessed. By employing post hoc Tukey-Kramer analysis for all possible pair-wise condition comparisons, we conclude that the average parameters are inadequate for the accurate chemical description of this cyanobacterial surface. It was determined that for this Gram-negative bacterium in batch culture, ligand distributions were influenced to a greater extent by nitrogen assimilation pathway than by growth phase.

  12. Characterization of Polymer Surfaces by the Use of Different Wetting Theories Regarding Acid-Base Properties

    Directory of Open Access Journals (Sweden)

    Eduard Kraus

    2017-01-01

    Full Text Available The existing wetting methods for the determination of acid-base properties on solid surfaces are discussed. Striving for a better understanding of the adhesive polymer interactions in adhesively joined polymers, the methods of Berger and van Oss-Chaudhury-Good were found as the most suitable methods for the investigation of wetting on solid polymer surfaces. Methods of nonlinear systems by Della Volpe and Siboni were adapted and evaluated on plastic surfaces. In the context of these investigations various data of the surface free energy as well as its components have been identified for a number of polymer surfaces by application of spatial equation solutions.

  13. Histologic and biomechanical evaluation of alumina-blasted/acid-etched and resorbable blasting media surfaces.

    Science.gov (United States)

    Bonfante, Estevam A; Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Hjerppe, Jenni; Witek, Lukasz; Coelho, Paulo G

    2012-10-01

    This study evaluated the early biomechanical fixation and bone-to-implant contact (BIC) of an alumina-blasted/acid-etched (AB/AE) compared with an experimental resorbable blasting media (RBM) surface in a canine model. Higher texturization was observed for the RBM than for the AB/AE surface, and the presence of calcium and phosphorus was only observed for the RBM surface. Time in vivo and implant surface did not influence torque. For both surfaces, BIC significantly increased from 2 to 4 weeks.

  14. Improving surface functional properties of tofu whey-derived peptides by chemical modification with fatty acids.

    Science.gov (United States)

    Matemu, Athanasia Oswald; Katayama, Shigeru; Kayahara, Hisataka; Murasawa, Hisashi; Nakamura, Soichiro

    2012-04-01

    Effect of acylation with saturated fatty acids on surface functional properties of tofu whey-derived peptides was investigated. Tofu whey (TW) and soy proteins (7S, 11S, and acid-precipitated soy protein [APP]) were hydrolyzed by Protease M 'Amano' G, and resulting peptide mixtures were acylated with esterified fatty acids of different chain length (6C to 18C) to form a covalent linkage between the carboxyl group of fatty acid and the free amino groups of peptide. Acylation significantly (P whey ultra filtered fraction (UFTW proteins.

  15. Leishmania Donovani Cell Surface Sialoglycans Regulate Susceptibility for Siglec Mediated Macrophage Invasion and Parasite Survival

    Directory of Open Access Journals (Sweden)

    Tripti De

    2012-02-01

    Full Text Available Glycoconjugates play a pivotal role in the survival of Leishmania parasites in destructive surroundings. An important constituent present on many glycoconjugates is sialic acid. By virtue of their peripheral position on oligosaccharide chains of glycoconjugates, sialic acids are well suited as molecular determinants of specific biological processes, including the interaction of pathogenic microorganisms with sialylated cellular receptors. Differences in a2,3- and a2,6-sialoglycan patterns detected in clonal virulent Leishmania donovani promastigotes, correlated with the level of a2,3- and a2,6-sialyltransferase activity present in these parasites. The role of macrophage sialic acid-receptors in uptake and survival of L.donovani was studied in the murine macrophage cell line raw 264.7. Macrophage invasion was dependent on the binding to Siglec-1, while suppression of MAPK signaling was mediated through Siglec-5. Sialic acid removal by neuraminidase treatment reduced parasite infectivity. The presence of trypsin resistant sialic acid residues in the neuraminidase treated parasites grown in a serum free medium in presence of sialoglycoconjugates indicated that the parasites could salvage sialic acid from exogenous sialoglycans and reutilize it for de novo glycoprotein sialylation in L.donovani parasites. Thus, our results demonstrate the involvement of sialoglycans in the invasion as well as the survival process of L.donovani parasites.

  16. Heterologous surface display on lactic acid bacteria: non-GMO alternative?

    OpenAIRE

    Zadravec, Petra; Štrukelj, Borut; Berlec, Aleš

    2015-01-01

    Lactic acid bacteria (LAB) are food-grade hosts for surface display with potential applications in food and therapy. Alternative approaches to surface display on LAB would avoid the use of recombinant DNA technology and genetically-modified organism (GMO)-related regulatory requirements. Non-covalent surface display of proteins can be achieved by fusing them to various cell-wall binding domains, of which the Lysine motif domain (LysM) is particularly well studied. Fusion proteins have been is...

  17. The Role of Organic Acids in the Acid-Base Status of Surface Waters at Bickford Watershed, Massachusetts

    Science.gov (United States)

    Eshleman, K. N.; Hemond, H. F.

    1985-10-01

    An experimental field study of the alkalinity and major ion budgets of Bickford watershed in central Massachusetts indicates that organic acid production by the ecosystem contributes measurably to surface water acidification. Applying the concepts of alkalinity, electroneutrality of solutions, and mass balance, organic acids were found to comprise 20% of all strong acid sources on one subcatchment annually, a value half as large as the measured bulk mineral acid deposition. Inorganic cation to anion ratios in Provencial Brook varied between 1.0 in winter and 1.6 during summer, suggesting the presence of up to 100 μeq/L of unmeasured charge from organic anions during the growing season. Base titrations and ultraviolet photooxidation experiments confirmed the existence of low pKa (3.5-5.0) acidic functional groups. A positive linear relationship between dissolved organic carbon (DOC) and anion deficit for a group of surface and groundwater samples indicates the DOC contains about 7.5 meq carboxylic groups per gram C. Biological factors related to both upland and wetland carbon metabolism apparently control this natural acidification phenomenon, which has not been documented on other watersheds in the northeastern United States for which annual alkalinity budgets have been determined.

  18. 类风湿关节炎患者外周血单个核细胞唾液酸结合免疫球蛋白样凝集素-1的表达及与疾病活动度的关系%The expression of sialic acid-binding immunoglobulin-like lectin-1 on peripheral blood mononuclear cells and its relationship with disease activity in rheumatoid arthritis

    Institute of Scientific and Technical Information of China (English)

    熊怡淞; 程悦; 吴艾霖; 王艳艳; 熊杰; 仲人前

    2013-01-01

    目的 观察唾液酸结合免疫球蛋白样凝集素-1 (Siglec-1)在类风湿关节炎(RA)患者外周血单个核细胞(PBMCs)上的表达水平,并探讨其与RA疾病活动度的关系.方法 分别采用流式细胞术及实时荧光定量反转录聚合酶链反应(RT-PCR)检测42例RA患者、28例骨关节炎患者和26名健康对照者外周血Siglec-1蛋白和mRNA表达,并将Siglec-1表达与28个关节疾病活动度评分(DAS28)以及超敏C反应蛋白(hs-CRP)作相关性分析.组间均数比较采用t检验,相关性分析采用Pearson相关分析.结果 流式细胞仪检测发现,RA组Siglec-1阳性细胞占PBMCs比例为(15.2±7.6)%,明显高于骨关节炎组[(2.3±2.6)%]和健康对照组[(2.1±1.6)%,t值分别为8.615,8.661;P均<0.01],并且表达Siglec-1的细胞主要为单核细胞;RA组Siglec-1 mRNA的相对表达量为(3.4±1.5),明显高于骨关节炎组(1.2±0.4)和健康对照组(1.0±0.4)(t值分别为3.446,3.966;P均<0.05).而骨关节炎组和健康对照组之间Siglec-1蛋白和mRNA表达差异无统计学意义(P>0.05).此外,RA患者Siglec-1的表达与DAS28及hs-CRP均呈正相关(r值分别为0.89,0.48;P均<0.01).结论 RA患者外周血PBMCs已经激活并高表达Siglec-1,Siglec-1可能作为无创性指标用于监测RA疾病活动度和炎症程度.%Objective To investigate the expression of sialic acid-binding immunoglobulin-like lectin-1 (Siglec-1) in the peripheral blood mononuclear cells (PBMCs) in patients with rheumatoid arthritis (RA),osteoarthritis (OA) and healthy controls and to explore the relationship between Siglec-1 expression and disease activity in RA.Methods Siglec-1 protein and mRNA levels were measured by flow cytometry and real-time quantitative reversetranscription-polymerase chain reaction (qRT-PCR) in 42 RA patients,28 OA patients and 26 healthy controls,respectively.The correlation studies between Siglec-1 and disease activity score 28 (DAS28) or C-reactive protein were

  19. Triangulating Nucleic Acid Conformations Using Multicolor Surface Energy Transfer.

    Science.gov (United States)

    Riskowski, Ryan A; Armstrong, Rachel E; Greenbaum, Nancy L; Strouse, Geoffrey F

    2016-02-23

    Optical ruler methods employing multiple fluorescent labels offer great potential for correlating distances among several sites, but are generally limited to interlabel distances under 10 nm and suffer from complications due to spectral overlap. Here we demonstrate a multicolor surface energy transfer (McSET) technique able to triangulate multiple points on a biopolymer, allowing for analysis of global structure in complex biomolecules. McSET couples the competitive energy transfer pathways of Förster Resonance Energy Transfer (FRET) with gold-nanoparticle mediated Surface Energy Transfer (SET) in order to correlate systematically labeled points on the structure at distances greater than 10 nm and with reduced spectral overlap. To demonstrate the McSET method, the structures of a linear B-DNA and a more complex folded RNA ribozyme were analyzed within the McSET mathematical framework. The improved multicolor optical ruler method takes advantage of the broad spectral range and distances achievable when using a gold nanoparticle as the lowest energy acceptor. The ability to report distance information simultaneously across multiple length scales, short-range (10-50 Å), mid-range (50-150 Å), and long-range (150-350 Å), distinguishes this approach from other multicolor energy transfer methods.

  20. Repeated exposure of acidic beverages on esthetic restorative materials: An in-vitro surface microhardness study.

    Science.gov (United States)

    Xavier, Arun M; Sunny, Steffy M; Rai, Kavita; Hegde, Amitha M

    2016-07-01

    A manifold increase in the consumption of aerated beverages has witnessed a twin increase in tooth wear and raised demand for esthetic restorative materials. This study aimed to evaluate the surface microhardness changes of esthetic restorative materials following treatment with aerated beverages in an in-vitro situation. The initial surface microhardness of the restorative materials GC Fuji II LC, GC Fuji IX, Nano Glass ionomer, Resin and Nano composite was recorded. These materials were studied under 3 groups that included those exposed to the acidic beverages daily, weekly once in a month and those that had no exposures at all. The final surface microhardness of the materials was recorded following experimentation and was subjected to statistical comparisons. The restorative materials were compared for their surface microhardness changes following respective treatments using the T-test and One-way ANOVA analysis. Inter-comparisons between the groups showed statistical significance (pmaterials revealed surface microhardness loss; the maximum reduction noticed with the Nano glass ionomer cement tested (pmaterials markedly reduced upon repeated exposures with acidic beverages; the product with phosphoric acid producing the maximum surface microhardness loss. Restorative materials, acidic beverages, surface microhardness, resin composites, glass ionomers.

  1. Chemical modification of chitosan film via surface grafting of citric acid molecular to promote the biomineralization

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: liuyang@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou 213164 (China); Engineering Research Center of Nano-Geo Materials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Shen, Xin; Zhou, Huan [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou 213164 (China); Wang, Yingjun [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Deng, Linhong, E-mail: dlh@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou 213164 (China)

    2016-05-01

    Graphical abstract: - Highlights: • Chitosan film was modified by surface grafting of citric acid. • The modified film has good hydrophilicity and moisture-retaining capacity. • The citric acid grafting treatment significantly promote the biomineralization. • MC3T3-E1 osteoblasts research confirms the biocompatibility of the film. - Abstract: We develop a novel chitosan–citric acid film (abbreviated as CS–CA) suitable for biomedical applications in this study. In this CS–CA film, the citric acid, which is a harmless organic acid has been extensively investigated as a modifying agent on carbohydrate polymers, was cross-linked by 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) onto the surface of chitosan (CS) film. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirms the graft copolymerization of the modified chitosan film (CS–CA). Surface wettability, moisturizing performance, the capacity of mineralization in vitro and biocompatibility of the films were characterized. After modification, this CS–CA film has good hydrophilicity. It is very evident that the citric acid grafting treatment significantly promotes the biomineralization of the chitosan based substrates. Cell experiments show that the MC3T3-E1 osteoblasts can adhere and proliferate well on the surface of CS–CA film. This CS–CA film, which can be prepared in large quantities and at low cost, should have potential application in bone tissue engineering.

  2. Protection of copper surface with phytic acid against corrosion in chloride solution.

    Science.gov (United States)

    Peca, Dunja; Pihlar, Boris; Ingrid, Milošev

    2014-01-01

    Phytic acid (inositol hexaphosphate) was tested as a corrosion inhibitor for copper in 3% sodium chloride. Phytic acid is a natural compound derived from plants, it is not toxic and can be considered as a green inhibitor. Electrochemical methods of linear polarization and potentiodynamic polarization were used to study the electrochemical behaviour and evaluate the inhibition effectiveness. To obtain the optimal corrosion protection the following experimental conditions were investigated: effect of surface pre-treatment (abrasion and three procedures of surface roughening), pre-formation of the layer of phytic acid, time of immersion and concentration of phytic acid. To evaluate the surface pre-treatment procedures the surface roughness and contact angle were measured. Optimal conditions for formation of phytic layer were selected resulting in the inhibition effectiveness of nearly 80%. Morphology and composition of the layer were further studied by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The layer of phytic acid with thickness in the nanometer range homogeneously covers the copper surface. The obtained results show that this natural compound can be used as a mildly effective corrosion inhibitor for copper in chloride solution.

  3. Preparation of PES ultrafiltration membranes with natural amino acids based zwitterionic antifouling surfaces

    Science.gov (United States)

    Xu, Chen; Liu, Xiaojiu; Xie, Binbin; Yao, Chen; Hu, Wenhan; Li, Yi; Li, Xinsong

    2016-11-01

    In this report, a simple and facile approach to enhance the antifouling property of poly(ether sulfone) (PES) ultrafiltration membrane was developed by grafting natural amino acids onto surface. First of all, poly(ether sulfone) composite membranes blended with poly(glycidyl methacrylate) were fabricated by phase inversion method followed by grafting of different types of natural amino acids onto the membrane surface through epoxy ring opening reaction. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR) and X-ray photoelectron spectroscopy (XPS) verified the substantial enrichment of amino acids onto the surface of PES membranes. The hydrophilicity of the PES membranes was improved after grafting amino acids. The mechanical property and morphologies of the PES membranes proved that their basic performances were not obviously affected by grafting reaction, and these parameters were all still in the typical range for ultrafiltration membranes. The antifouling property of the grafted PES membranes against bovine serum albumin (BSA) and lysozyme (Lyz) was investigated in detail. It was found that PES membranes incorporated with neutral amino acids exhibited higher fouling resistance to both BSA and Lyz than the parent PES membrane. It can be ascribed to the formation of zwitterionic structure on the surface consisting of protonated secondary amino cations and carboxyl anions. Meanwhile, PES membranes grafted with charged amino acids had better antifouling properties against protein with same electric charges and improved adsorption related to protein with opposite electric charges. Furthermore, the ultrafiltration performance of the zwitterionic PES membranes was evaluated. The results showed that the modified membranes possessed of enhanced pure water flux, relative flux recovery and mildly lower rejection. The Darcy's Law analysis illustrated that the acidic amino acid grafted PES membranes had much lower permeation

  4. Superhydrophilicity of a nanofiber-covered aluminum surface fabricated via pyrophosphoric acid anodizing

    Science.gov (United States)

    Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

    2016-12-01

    A superhydrophilic aluminum surface covered by numerous alumina nanofibers was fabricated via pyrophosphoric acid anodizing. High-density anodic alumina nanofibers grow on the bottom of a honeycomb oxide via anodizing in concentrated pyrophosphoric acid. The water contact angle on the nanofiber-covered aluminum surface decreased with time after a 4 μL droplet was placed on the surface, and a superhydrophilic behavior with a contact angle measuring 2.2° was observed within 2 s; this contact angle is considerably lower than those observed for electropolished and porous alumina-covered aluminum surfaces. There was no dependence of the superhydrophilicity on the density of alumina nanofibers fabricated via different constant voltage anodizing conditions. The superhydrophilic property of the surface covered by anodic alumina nanofibers was maintained during an exposure test for 359 h. The quick-drying and snow-sliding behaviors of the superhydrophilic aluminum covered with anodic alumina nanofibers were demonstrated.

  5. Experimental Investigation and Analysis of Mercerized and Citric Acid Surface Treated Bamboo Fiber Reinforced Composite

    Science.gov (United States)

    De, Jyotiraman; Baxi, R. N., Dr.

    2017-08-01

    Mercerization or NaOH fiber surface treatment is one of the most popular surface treatment processes to make the natural fibers such as bamboo fibers compatible for use as reinforcing material in composites. But NaOH being a chemical is hazardous and polluting to the nature. This paper explores the possibility of use of naturally derived citric acid for bamboo fiber surface treatment and its comparison with NaOH treated Bamboo Fiber Composites. Untreated, 2.5 wt% NaOH treated and 5 wt% citric acid treated Bamboo Fiber Composites with 5 wt% fiber content were developed by Hand Lay process. Bamboo mats made of bamboo slivers were used as reinforcing material. Mechanical and physical characterization was done to compare the effects of NaOH and citric acid bamboo fiber surface treatment on mechanical and physical properties of Bamboo Fiber Composite. The experiment data reveals that the tensile and flexural strength was found to be highest for citric acid and NaOH treated Bamboo Fiber Composite respectively. Water absorption tendency was found more than the NaOH treated Bamboo Fiber Composites. SEM micrographs used to analyze the morphology of fracture surface of tensile test specimens confirm improvement in fiber-matrix interface bonding due to surface treatment of bamboo fibers.

  6. Surface modification of poly(L-lactic acid) with biomolecules to promote endothelialization.

    Science.gov (United States)

    Xia, Yun; Boey, Freddy; Venkatraman, Subbu S

    2010-09-01

    Rapid endothelialization is important for biodegradable blood-contacting devices not only to prevent thrombosis but also to prevent degradation debris from entering the bloodstream and causing further complications. Here the authors report a three-step surface modification method, by which biomolecules, such as gelatin and chitosan, are covalently immobilized on the surface of plasma-treated poly(L-lactic acid) (PLLA) via -COOH groups introduced by acrylic acid grafting polymerization. Surface characterization techniques, including x-ray photoelectron spectroscopy, contact angle measurement, and colorimetric methods for surface density of functional groups, proved the feasibility and stability of this surface modification method. Surface wettability was increased by biomolecules immobilization. The -COOH surface density was measured to be 4.17±0.15 μmol/cm(2), the and amount of gelatin immobilized was 4.8 μg/cm(2). Human umbilical vein endothelial cell was used during in vitro study at seeding density of 10(4) cells/cm(2). PLLA-gAA-gelatin surface was found to enhance cell adhesion, spreading, focal adhesion formation, and proliferation significantly. Chitosan-modified PLLA shows marginally improvement in cell adhesion and proliferation. Endothelialization was achieved within 7 days on both modified PLLA surfaces. In conclusion, this work demonstrates the feasibility of the surface modification method, and its ability to promote complete endothelialization for cardiovascular applications.

  7. Relationship between surface acidity and activity of solid-acid catalysts in vapour phase dehydration of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Mollavali, M.; Atashi, H. [Department of Chemical Engineering, Faculty of Engineering, University of Sistan and Baluchestan, P.O. Box 98164-161, Zahedan (Iran); Yaripour, F.; Mohammadi-Jam, S. [Catalyst Research Group, Petrochemical Research and Technology Company, National Petrochemical Company, 14358, Tehran (Iran)

    2009-09-15

    A series of solid-acid catalysts comprised of {gamma}-alumina and modified {gamma}-alumina with different of silica were prepared by co-precipitation method. The catalysts were characterized using XRD, TGA, NH{sub 3}-TPD and BET techniques. Dehydration of methanol to dimethyl ether (DME) on solid-acid catalysts was studied in a fixed-bed reactor at the same operating conditions (T = 300 C, P = 16 bar, WHSV = 26.07 h{sup -} {sup 1}). According to the experimental results, silica-modified catalysts have shown better performance compared to the pure {gamma}-alumina. It was found that surface areas increase with increasing silica loading. The results of NH{sub 3}-TPD analysis showed that the surface acidity of aluminosilicate catalysts increases with increase in SiO{sub 2}/Al{sub 2}O{sub 3} molar ratio. Also, it was found that the catalysts with highest portion of weak and/or moderate acid sites exhibit the best catalytic performance and stability. The sample with 3 wt.% silica loading has exhibited the best activity for methanol conversion. (author)

  8. N-Acetylneuraminyllactosylceramide, GM3-NeuAc, a new influenza A virus receptor which mediates the adsorption-fusion process of viral infection. Binding specificity of influenza virus A/Aichi/2/68 (H3N2) to membrane-associated GM3 with different molecular species of sialic acid.

    Science.gov (United States)

    Suzuki, Y; Matsunaga, M; Matsumoto, M

    1985-02-10

    Agglutinates of native chicken erythrocytes caused by influenza virus A/Aichi/2/68 (H3N2) at 4 degrees C were potently fused and lysed at low pH (optimum pH 5.3) at 37 degrees C. Exogenous gangliosides GM3 (Sia alpha 2-3Gal beta 1-4Glc beta 1-ceramide) and GM2 (GalNAc beta 1-4(Sia alpha 2-3)-Gal beta 1-4Glc beta 1-ceramide) were integrated into the membranes of chicken asialoerythrocytes within 5-min incubation at 37 degrees C. We found that the incorporation of ganglioside GM3 containing N-acetylneuraminic acid into asialoerythrocytes restored the biological responsiveness to the virus as established by agglutination at 4 degrees C and fusion and hemolysis at 37 degrees C at pH 5.3. Biological responsiveness of GM3-NeuAc-erythrocytes to the virus was considerably higher than that of GM3-NeuGc-erythrocytes under the same experimental conditions. Treatment of the GM3-NeuAc-erythrocytes with neuraminidase again resulted in the complete abolishment of the response to the virus. Erythrocytes containing GM2-NeuAc showed no detectable biological responses toward the virus. The above results indicate that the hemagglutinin of influenza virus A/Aichi/2/68 (H3N2) recognizes the sialyloligosaccharide chain of ganglioside GM3 as its receptor which mediates the adsorption and fusion process on the virus entry into the host cells and has more preferential specificity for binding to N-acetylneuraminic acid-containing GM3 than that to N-glycolyl type in the target cell membranes.

  9. Kinetics of gas phase formic acid decomposition on platinum single crystal and polycrystalline surfaces

    Science.gov (United States)

    Detwiler, Michael D.; Milligan, Cory A.; Zemlyanov, Dmitry Y.; Delgass, W. Nicholas; Ribeiro, Fabio H.

    2016-06-01

    Formic acid dehydrogenation turnover rates (TORs) were measured on Pt(111), Pt(100), and polycrystalline Pt foil surfaces at a total pressure of 800 Torr between 413 and 513 K in a batch reactor connected to an ultra-high vacuum (UHV) system. The TORs, apparent activation energies, and reaction orders are not sensitive to the structure of the Pt surface, within the precision of the measurements. CO introduced into the batch reactor depressed the formic acid dehydrogenation TOR and increased the reaction's apparent activation energies on Pt(111) and Pt(100), consistent with behavior predicted by the Temkin equation. Two reaction mechanisms were explored which explain the formic acid decomposition mechanism on Pt, both of which include dissociative adsorption of formic acid, rate limiting formate decomposition, and quasi-equilibrated hydrogen recombination and CO adsorption. No evidence was found that catalytic supports used in previous studies altered the reaction kinetics or mechanism.

  10. Study of mixed Ca-Zn hydroxyapatite surface modified by lactic acid

    Energy Technology Data Exchange (ETDEWEB)

    Turki, Thouraya; Aissa, Abdallah [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia); Bac, Christophe Goze [Laboratoire Charles Coulomb, UMR 5221 CNRS/UM2, Universite Montpellier 2, Place E. Bataillon, 34095 Montpellier (France); Rachdi, Ferid, E-mail: Ferid.Rachdi@univ-montp2.fr [Laboratoire Charles Coulomb, UMR 5221 CNRS/UM2, Universite Montpellier 2, Place E. Bataillon, 34095 Montpellier (France); Debbabi, Mongi [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia)

    2012-07-01

    The new hybrid inorganic-organic composites, Ca{sub (10-x)}Zn{sub x}(PO{sub 4}){sub 6}(OH){sub 2}-lactic acid, at different amounts of zinc and lactic acid were prepared by dissolution of the organic compound in an hydroxyapatite suspension. They were characterized by XRD, IR, MAS NMR ({sup 13}C and {sup 1}H) and chemical analysis. The crystallinity was slightly affected by the presence of organic fragments. IR and ({sup 13}C and {sup 1}H) MAS NMR measurements indicate that the carboxylic groups of the acid interact with calcium and zinc ions of hydroxyapatite surface. Chemical analysis displays that zinc promotes the acid grafting. A mechanism of surface modification is proposed based on the obtained results.

  11. Surface modification of cellulosic substrates via atmospheric pressure plasma polymerization of acrylic acid: Structure and properties

    Science.gov (United States)

    Garcia-Torres, Jose; Sylla, Dioulde; Molina, Laura; Crespo, Eulalia; Mota, Jordi; Bautista, Llorenç

    2014-06-01

    Surface chemical modification of cellulose-based substrates has been carried out by atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) of acrylic acid. The structure/properties relationship of the samples was studied as a function of the plasma experimental conditions. Acrylic acid monomer/helium ratio and treatment speed clearly influences the wettability properties of the paper substrate: advancing contact angle values were reduced to the half if compare to non-treated paper. Surface morphology of the films did not greatly vary at short polymerization times but fibers were covered by a poly(acrylic acid) film at longer times. FTIR and XPS techniques allowed detecting the retention of carboxylic acid groups/moieties. The possibility to quickly design architectures with tunable carboxylic functions by modifying the plasma processing parameters is shown.

  12. Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

    Directory of Open Access Journals (Sweden)

    Elizabeth I. Braun

    2016-06-01

    Full Text Available It is well known that surfactant-suspended carbon nanotube (CNT samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ∼40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

  13. Direct monophasic replacement of fatty acid by DMSA on SPION surface

    Science.gov (United States)

    Gogoi, M.; Deb, P.; Vasan, G.; Keil, P.; Kostka, A.; Erbe, A.

    2012-10-01

    Tailoring the surface and understanding the surface characteristics is necessary for biomedical applications of superparamagnetic nanoparticles. In this paper, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared by thermal decomposition of iron nitrate in presence of stearic acid as surfactant. Due to the multilayer organization of surfactant molecules over the nanoparticle surface, the surface potential can be tuned by pH changes and hence the nanoparticles can be made dispersible in nonpolar as well as in polar solvents. We have presented a simple, facile procedure for controlled replacement of stearic acid from maghemite surface and subsequent derivatization by biocompatible dimercaptosuccinic acid (DMSA) to obtain ultrastable hydrophilic nanoparticles with unaltered morphology, phase and properties. The surface chemistry of the functionalized SPIONs was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) revealing the presence of bound and unbound thiol groups and disulfides, leading to its prolonged stability in aqueous medium. The consequence of spatially selective functionalization on the stability and solubility of surface hydrophilic SPION has also been realized.

  14. Probing the interaction of individual amino acids with inorganic surfaces using atomic force spectroscopy.

    Science.gov (United States)

    Razvag, Yair; Gutkin, Vitaly; Reches, Meital

    2013-08-13

    This article describes single-molecule force spectroscopy measurements of the interaction between individual amino acid residues and inorganic surfaces in an aqueous solution. In each measurement, there is an amino acid residue, lysine, glutamate, phenylalanine, leucine, or glutamine, and each represents a class of amino acids (positively or negatively charged, aromatic, nonpolar, and polar). Force-distance curves measured the interaction of the individual amino acid bound to a silicon atomic force microscope (AFM) tip with a silcon substrate, cut from a single-crystal wafer, or mica. Using this method, we were able to measure low adhesion forces (below 300 pN) and could clearly determine the strength of interactions between the individual amino acid residues and the inorganic substrate. In addition, we observed how changes in the pH and ionic strength of the solution affected the adsorption of the residues to the substrates. Our results pinpoint the important role of hydrophobic interactions among the amino acids and the substrate, where hydrophobic phenylalanine exhibited the strongest adhesion to a silicon substrate. Additionally, electrostatic interactions also contributed to the adsorption of amino acid residues to inorganic substrates. A change in the pH or ionic strength values of the buffer altered the strength of interactions among the amino acids and the substrate. We concluded that the interplay between the hydrophobic forces and electrostatic interactions will determine the strength of adsorption among the amino acids and the surface. Overall, these results contribute to our understanding of the interaction at the organic-inorganic interface. These results may have implications for our perception of the specificity of peptide binding to inorganic surfaces. Consequently, it would possibly lead to a better design of composite materials and devices.

  15. Preparation of PES ultrafiltration membranes with natural amino acids based zwitterionic antifouling surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen; Liu, Xiaojiu; Xie, Binbin; Yao, Chen [School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189 (China); Hu, Wenhan; Li, Yi [Suzhou Faith & Hope Membrane Technology Co., Ltd., Suzhou, 215000 (China); Li, Xinsong, E-mail: lixs@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189 (China)

    2016-11-01

    Highlights: • Amino acids have been successfully grafted onto the surface of PES membranes via amino groups induced epoxy ring opening. • Zwitterionic PES ultrafiltration membranes exhibit excellent antifouling performance and improved permeation properties. • A facile strategy to combat fouling of PES ultrafiltration membranes is developed by grafting natural amino acids. - Abstract: In this report, a simple and facile approach to enhance the antifouling property of poly(ether sulfone) (PES) ultrafiltration membrane was developed by grafting natural amino acids onto surface. First of all, poly(ether sulfone) composite membranes blended with poly(glycidyl methacrylate) were fabricated by phase inversion method followed by grafting of different types of natural amino acids onto the membrane surface through epoxy ring opening reaction. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR) and X-ray photoelectron spectroscopy (XPS) verified the substantial enrichment of amino acids onto the surface of PES membranes. The hydrophilicity of the PES membranes was improved after grafting amino acids. The mechanical property and morphologies of the PES membranes proved that their basic performances were not obviously affected by grafting reaction, and these parameters were all still in the typical range for ultrafiltration membranes. The antifouling property of the grafted PES membranes against bovine serum albumin (BSA) and lysozyme (Lyz) was investigated in detail. It was found that PES membranes incorporated with neutral amino acids exhibited higher fouling resistance to both BSA and Lyz than the parent PES membrane. It can be ascribed to the formation of zwitterionic structure on the surface consisting of protonated secondary amino cations and carboxyl anions. Meanwhile, PES membranes grafted with charged amino acids had better antifouling properties against protein with same electric charges and improved adsorption

  16. Surface-structured molecular sensor for the optical detection of acidity.

    Science.gov (United States)

    Martínez-Otero, Alberto; Evangelio, Emilia; Alibés, Ramon; Bourdelande, José Luis; Ruiz-Molina, Daniel; Busqué, Félix; Hernando, Jordi

    2008-04-01

    In this letter, we report on the development of a surface molecular sensor for the detection of acidity. Lithographically controlled wetting deposition has been applied to form the nanostructure of a new fluorescent compound with three protonation states featuring different optical properties on a glass substrate. Atomic force microscopy demonstrates the functionalization of the surface with ordered arrays of the sensor molecules. The fluorescence properties of the resulting nanopattern at different pH values have been investigated by confocal fluorescene microsopy, thus revealing the fast, sensitive, reversible response of the prepared nanosensor to gas flows of varying acidity.

  17. Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

    Science.gov (United States)

    Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin; Hao, Jingcheng

    2017-03-01

    A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

  18. Preparation and UV-light Absorption Property of Oleic Acid Surface Modified ZnO Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    KANG Jong-hun; GUO Yu-peng; CHEN Yue; WANG Zi-chen

    2011-01-01

    Syntheses of zince oxide(ZnO) nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry(XRD), transmission electron microscopy(TEM), infrared spectroscopy(IR) and UV-Vis spectroscopy. The prepared ZnO nanoparticles were nearly spherical and highly crystalline with an average size of 29 nm. In addition, high UV-light absorption properties of oleic acid surface modified ZnO nanoparticles were successfully obtained for a dispersion of ZnO nanoparticles in ethanol.

  19. Acidity-Facilitated Mobilization of Surface Clay Colloid from Natural Sand Medium

    Science.gov (United States)

    Huang, Y.; Wang, C.; Mohanty, B. P.

    2010-12-01

    Colloid mobilization and migration in a soil system has attracted increasing scrutiny for its role in facilitating colloid-borne transport of contaminants in the environments. In many previous studies, pH was evoked as a major factor in mobilizing surface colloids through inducing favorable surface charge and electrostatic conditions. The possible direct role of acidity with H+ as a chemical agent has remained largely obscured behind the indirect role of pH. In this study, we demonstrated through column flow-through tests that cyclical elution of natural sand media with weak acid and base solutions can greatly facilitate detachment and transport of surface clay colloids. We found that while elevating pH to an alkaline condition helped release the loosely-attached surface clays, a pretreatment with H+ could facilitate the mobilization of chemically-bonded clay colloids through lysing of labile Ca and Mg ions. A quantitative relation was observed that 1 mmol H+ could lyse about 0.5 mmol Ca2+ and Mg2+ and subsequently resulted in a release of about 1,200 mg clay during base elution when repulsive force between particles dominated. Natural organic acids such as citric acid and acetic acid in environment-relevant low concentrations (5.0) were as effective as HCl with a stronger acidic condition. The small mass ratio of Ca and Mg over colloid released and the nature of weak acid used suggest that the mobilization was less likely due to dissolution of cement casing than lysing of labile interstitial Ca and Mg by H+, which severed Ca and Mg bridging bonds between particles. Natural acidity is generated in abundance from various bio- and geochemical processes; e.g., many plants produce citric acid through citric acid cycle metabolism; biodegradation of dead organic matter forms humic acids. We postulate that natural proton dynamics in tendon with pH oscillation accompanied with various soil biogeochemical processes could play a major role in subsurface clay transport

  20. Surface exposed amino acid differences between mesophilic and thermophilic phosphoribosyl diphosphate synthase

    DEFF Research Database (Denmark)

    Hove-Jensen, Bjarne; McGuire, James N

    2004-01-01

    The amino acid sequence of 5-phospho-alpha-D-ribosyl 1-diphosphate synthase from the thermophile Bacillus caldolyticus is 81% identical to the amino acid sequence of 5-phospho-alpha-D-ribosyl 1-diphosphate synthase from the mesophile Bacillus subtilis. Nevertheless the enzyme from the two organisms...... competitive with respect to ATP. A predicted structure of the B. caldolyticus enzyme based on homology modelling with the structure of B. subtilis 5-phospho-alpha-D-ribosyl 1-diphosphate synthase shows 92% of the amino acid differences to be on solvent exposed surfaces in the hexameric structure....

  1. Synthesis, Crystal Structure, and Hirshfeld Surface Analysis of Ciprofloxacin-Salicylic Acid Molecular Salt

    OpenAIRE

    Ravikumar Nagalapalli; Shankar Yaga Bheem

    2014-01-01

    In the present study, ciprofloxacin-salicylic acid molecular salt has been synthesized and preliminarily characterized by FT-IR spectroscopy. The single crystal X-ray diffraction (SCXRD) reveals the proton transfer from carboxylic acid group of salicylic acid to piperazine moiety in ciprofloxacin confirming the formation of new molecular salt. The molecular packing of the molecular salt is mainly supported by N+–H⋯O−, O–H⋯O, C–H⋯F, C–H⋯π, and π-π interactions. The 3D Hirshfeld surfaces and th...

  2. Synthesis, Crystal Structure, and Hirshfeld Surface Analysis of Ciprofloxacin-Salicylic Acid Molecular Salt

    Directory of Open Access Journals (Sweden)

    Ravikumar Nagalapalli

    2014-01-01

    Full Text Available In the present study, ciprofloxacin-salicylic acid molecular salt has been synthesized and preliminarily characterized by FT-IR spectroscopy. The single crystal X-ray diffraction (SCXRD reveals the proton transfer from carboxylic acid group of salicylic acid to piperazine moiety in ciprofloxacin confirming the formation of new molecular salt. The molecular packing of the molecular salt is mainly supported by N+–H⋯O−, O–H⋯O, C–H⋯F, C–H⋯π, and π-π interactions. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated for intermolecular hydrogen bonding interactions.

  3. Surface and thermal properties of collagen/hyaluronic acid blends containing chitosan.

    Science.gov (United States)

    Lewandowska, Katarzyna; Sionkowska, Alina; Grabska, Sylwia; Kaczmarek, Beata

    2016-11-01

    The structure and surface properties of binary and ternary blends containing collagen (Coll), hyaluronic acid (HA) and chitosan (Ch) were investigated by contact angle measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Thin films of Coll/HA and Coll/HA/Ch blends have been formed by casting methods from aqueous acid solutions. The surface roughness, hydrophobic/hydrophilic character and thermal stability of Coll/HA were changed after addition of chitosan. Thermal stability of binary blends increase upon the addition of chitosan. The results of contact angle and the surface free energy revealed that hyaluronic acid films are more polar than collagen and chitosan films. The surface energy and its polar and dispersive components of binary and ternary blends were calculated and more hydrophilic films were produced by the addition of HA and chitosan, also resulting in more thermally stabile materials. These results demonstrate that collagen interacts with hyaluronic acid and chitosan changing the surface properties of polymer films.

  4. Dispersion of ceria nanoparticles on γ-alumina surface functionalized using long chain carboxylic acids

    Science.gov (United States)

    Ledwa, Karolina Anna; Kępiński, Leszek

    2017-04-01

    Dispersion and stability of nanoparticles on a support is determined by the interaction between these phases. In case of hydrophobic nanoparticles (e.g. synthesized by reverse microemulsion method) the interaction with hydrophilic support (e.g. γ-Al2O3) is weak and agglomeration as well as poor resistance to sintering may cause problems. The bonding of the particles to the support may be effectively strengthened by proper modification of the support, e.g. by adsorption of hydrophobic compounds on its surface. In this work decanoic, myristic, stearic and oleic acid were used for the first time to cover γ-Al2O3 surface in order to enhance the dispersion of ceria nanoparticles deposited afterward by impregnation on such support. TGA and FTIR methods revealed that at monolayer coverage (1.1-2.5 molecules per nm2) the acid molecules are firmly bounded to the alumina surface. Morphology, textural properties, phase composition and reducibility of the CeO2/γ-Al2O3 samples were investigated using TEM, SEM, BET, XRD and H2-TPR methods. It has been shown that deposition of CeO2 nanoparticles on γ-Al2O3 surface covered with all studied acids enhances its dispersion, stability and reducibility. The most effective modification of the γ-Al2O3 surface was obtained at loading of 2.3 molecules of decanoic acid per nm2 of the support.

  5. DNA adsorption to and elution from silica surfaces: influence of amino acid buffers.

    Science.gov (United States)

    Vandeventer, Peter E; Mejia, Jorge; Nadim, Ali; Johal, Malkiat S; Niemz, Angelika

    2013-09-19

    Solid phase extraction and purification of DNA from complex samples typically requires chaotropic salts that can inhibit downstream polymerase amplification if carried into the elution buffer. Amino acid buffers may serve as a more compatible alternative for modulating the interaction between DNA and silica surfaces. We characterized DNA binding to silica surfaces, facilitated by representative amino acid buffers, and the subsequent elution of DNA from the silica surfaces. Through bulk depletion experiments, we found that more DNA adsorbs to silica particles out of positively compared to negatively charged amino acid buffers. Additionally, the type of the silica surface greatly influences the amount of DNA adsorbed and the final elution yield. Quartz crystal microbalance experiments with dissipation monitoring (QCM-D) revealed multiphasic DNA adsorption out of stronger adsorbing conditions such as arginine, glycine, and glutamine, with DNA more rigidly bound during the early stages of the adsorption process. The DNA film adsorbed out of glutamate was more flexible and uniform throughout the adsorption process. QCM-D characterization of DNA elution from the silica surface indicates an uptake in water mass during the initial stage of DNA elution for the stronger adsorbing conditions, which suggests that for these conditions the DNA film is partly dehydrated during the prior adsorption process. Overall, several positively charged and polar neutral amino acid buffers show promise as an alternative to methods based on chaotropic salts for solid phase DNA extraction.

  6. Clinical value of combined detection of serum total sialic acid, sialidase and high sensitivity C-reactive protein in patients with acute myocardial infarction%血清总唾液酸、唾液酸酶和超敏C反应蛋白联合检测对急性心肌梗死患者诊断和预后评估的临床价值

    Institute of Scientific and Technical Information of China (English)

    周方元; 李艳; 戴雯

    2016-01-01

    目的:探讨联合检测血清总唾液酸(TSA)、唾液酸酶(NEU)及超敏C反应蛋白(hs-CRP)在急性心肌梗死(AMI)患者的诊断和预后评估中的临床价值。方法收集2015年8~12月武汉大学人民医院的AMI患者210例(病例组)及同期体检健康者99例(对照组),其中病例组患者根据AMI类型分为ST段抬高型AMI组(STEMI组)和非ST段抬高型AMI组(NSTEMI组);根据AMI部位,分为前壁梗死组和下壁梗死组;根据是否院内死亡,分为院内死亡组和存活组。分别检测各组受检者的血清TSA、NEU、hs-CRP的浓度,并对其结果进行统计学分析。结果病例组患者的血清TSA水平为717 mg/L,明显高于对照组的568 mg/L,差异有统计学意义(U=2346.5,P0.05);前壁梗死组患者的血清TSA水平为746 mg/L,明显高于下壁梗死组的648 mg/L,血清hs-CRP水平为19.63 mg/dL,明显高于下壁梗死组的7.80 mg/dL,差异均有统计学意义(U=2302.5、2169.5,P均<0.01);院内死亡组的TSA水平为948 mg/L,明显高于存活组的697 mg/L,hs-CRP水平为58.37 mg/mL,明显高于存活组的11.00 mg/mL,差异均有统计学意义(U=1006.5、1052.0,P均<0.01);AMI患者血清TSA与hs-CRP呈显著负相关(r=0.623,P<0.01);绘制受试者工作特征曲线后显示,用血清TSA诊断AMI时,曲线下面积为86.0%(P<0.01),用血清hs-CRP诊断AMI时,曲线下面积为97.3%(P<0.01),联合血清TSA和hs-CRP诊断AMI时,曲线下面积为97.4%(P<0.01)。结论联合检测血清TSA、NEU和hs-CRP对于AMI患者的诊断和预后评估都具有重要意义。%Objective To evaluate the clinical value of combined detection of serum total sialic acid (TSA), neuramidinase (NEU) and high sensitivity C-reactive protein (hs-CRP) in the diagnosis and prognosis evaluation of acute myocardial infarction (AMI). Methods Ninety-nine healthy subjects (control group) and 210 AMI patients (case group) who visited the Renmin Hospital of Wuhan

  7. Decoupling the contribution of dispersive and acid-base components of surface energy on the cohesion of pharmaceutical powders.

    Science.gov (United States)

    Shah, Umang V; Olusanmi, Dolapo; Narang, Ajit S; Hussain, Munir A; Tobyn, Michael J; Heng, Jerry Y Y

    2014-11-20

    This study reports an experimental approach to determine the contribution from two different components of surface energy on cohesion. A method to tailor the surface chemistry of mefenamic acid via silanization is established and the role of surface energy on cohesion is investigated. Silanization was used as a method to functionalize mefenamic acid surfaces with four different functional end groups resulting in an ascending order of the dispersive component of surface energy. Furthermore, four haloalkane functional end groups were grafted on to the surface of mefenamic acid, resulting in varying levels of acid-base component of surface energy, while maintaining constant dispersive component of surface energy. A proportional increase in cohesion was observed with increases in both dispersive as well as acid-base components of surface energy. Contributions from dispersive and acid-base surface energy on cohesion were determined using an iterative approach. Due to the contribution from acid-base surface energy, cohesion was found to increase ∼11.7× compared to the contribution from dispersive surface energy. Here, we provide an approach to deconvolute the contribution from two different components of surface energy on cohesion, which has the potential of predicting powder flow behavior and ultimately controlling powder cohesion.

  8. Molecular modeling of the surface charging of hematite. I. The calculation of proton affinities and acidities on a surface

    Science.gov (United States)

    Wasserman, Evgeny; Rustad, James R.; Felmy, Andrew R.

    1999-03-01

    Calculation of the energy of a charged defect on a surface in supercell geometry is discussed. An important example of such a calculation is evaluation of surface proton affinities and acidities, as adding or removing a proton creates a charged unit cell. Systems with periodic boundary conditions in three spatial directions and a vacuum gap between slabs are demonstrated to be inadequate for unit cells having non-zero ionic charge and uniform neutralizing background. In such a system the calculated energy diverges linearly with the thickness of the vacuum gap. A system periodic in two directions and finite in the direction perpendicular to the surface (2-D PBC) with the neutralizing background distributed as the surface charge density is free from this problem. Furthermore, the correction for the interaction of the charged defect with its own translational images is needed to speed up the convergence to the infinite dilution limit. The expression for the asymptotic correction for the energy of interaction of a charged defect with its translational images in 2-D PBC geometry has been developed in this study. The asymptotic correction is evaluated as the interaction energy of a 2-D translationally periodic array of point charges located above and below the plate of non-uniform dielectric. This is a generalization of the method of M. Leslie and M.J. Gillan [J. Phys. C, 18 (1985) 973] for the calculation of the energy of a charged defect in bulk crystals. The usefulness of this correction was demonstrated on two test cases involving the calculation of proton affinity and acidity at the (012) surface of hematite. The proposed method is likely to be important in ab initio calculations of the energy effect of the surface protonation reactions, where computational limitations dictate a small size for the unit cell.

  9. Grain boundaries at the surface of consolidated MgO nanocrystals and acid-base functionality.

    Science.gov (United States)

    Vingurt, Dima; Fuks, David; Landau, Miron V; Vidruk, Roxana; Herskowitz, Moti

    2013-09-21

    The increase of the surface basicity-acidity of MgO material by factors of 1.8-3.0 due to consolidation of its nanocrystals was demonstrated by the indicator titration. It was shown that the parallel increase of surface acidity and basicity is attributed to the formation of grain boundaries (GB) after MgO aerogel densification. A simple model predicting the increase of surface acidity-basicity of MgO that correlates with the results of direct measurements was proposed. The model is based on the study of the fine atomic structure at GB surface areas in consolidated MgO nanocrystals in the framework of Density Functional Theory. It is found that the displacements of coordinatively unsaturated surface ions near the GB are significant at the distances ~3-4 atomic layers from the geometrical contact plane between nanocrystals. The detailed analysis of atomic positions inside GB demonstrated the coordination deficiency of surface atoms at the GB areas leading to the formation of stretched bonds and to creation of low coordinated surface ions due to splitting of coordination numbers of surface atoms belonging to GB areas. Density of states for electrons shows the existence of additional states in the band gap close to the bottom of the conduction band. The adsorption energy of CO2 molecules atop oxygen atoms exposed at surface GB areas is of the same order of magnitude as that reported for oxygen atoms at crystallographic edges and corners of MgO crystals. It provides additional options for bonding of molecules at the surface of nanocrystalline MgO increasing the adsorption capacity and catalytic activity.

  10. Sb Surface Modification of Pd by Mimetic Underpotential Deposition for Formic Acid Oxidation

    OpenAIRE

    Long-Long Wang; Xiao-Lu Cao; Ya-Jun Wang; Qiao-Xia Li

    2015-01-01

    The newly proposed mimetic underpotential deposition (MUPD) technique was extended to modify Pd surfaces with Sb through immersing a Pd film electrode or dispersing Pd/C powder in a Sb(III)-containing solution blended with ascorbic acid (AA). The introduction of AA shifts down the open circuit potential of Pd substrate available to achieve suitable Sb modification. The electrocatalytic activity and long-term stability towards HCOOH electrooxidation of the Sb modified Pd surfaces (film elect...

  11. Improvement of surface acidity and structural regularity of Zr-modified mesoporous MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.F. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico)]. E-mail: chenlf2001@yahoo.com; Norena, L.E. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico); Navarrete, J. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico); Wang, J.A. [Laboratorio de Catalisis y Materiales, SEPI-ESIQIE, Instituto Politecnico Nacional, Av. Politecnico S/N, Col. Zacatenco, 07738 Mexico D.F. (Mexico)

    2006-06-10

    This work reports the synthesis and surface characterization of a Zr-modified mesoporous MCM-41 solid with an ordered hexagonal arrangement, prepared through a templated synthesis route, using cetyltrimethylammonium chloride as the template. The surface features, crystalline structure, textural properties and surface acidity of the materials were characterized by in situ Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), N{sub 2} physisorption isotherms, {sup 29}Si MAS-NMR and in situ FT-IR of pyridine adsorption. It is evident that the surfactant cations inserted into the network of the solids during the preparation could be removed by calcination of the sample above 500 deg. C. The resultant material showed a large surface area of 680.6 m{sup 2} g{sup -1} with a uniform pore diameter distribution in a very narrow range centered at approximately 2.5 nm. Zirconium incorporation into the Si-MCM-41 framework, confirmed by {sup 29}Si MAS-NMR analysis, increased not only the wall thickness of the mesopores but also the long-range order of the periodically hexagonal structure. Both, Lewis and Broensted acid sites, were formed on the surface of the Zr-modified MCM-41 solid. Compared to Si-MCM-41 on which only very weak Lewis acid sites were formed, the densities of both Lewis and Broensted acid sites and the strength of the acidity on the Zr-modified sample were significantly increased, indicating that the incorporation of zirconium greatly enhances the acidity of the material.

  12. Adsorption kinetics of organophosphonic acids on plasma-modified oxide-covered aluminum surfaces.

    Science.gov (United States)

    Giza, M; Thissen, P; Grundmeier, G

    2008-08-19

    Tailoring of oxide chemistry on aluminum by means of low-pressure water and argon plasma surface modification was performed to influence the kinetics of the self-assembly process of octadecylphosphonic acid monolayers. The plasma-induced surface chemistry was studied by in situ FTIR reflection-absorption spectroscopy (IRRAS). Ex situ IRRAS and X-ray photoelectron spectroscopy were applied for the analysis of the adsorbed self-assembled monolayers. The plasma-induced variation of the hydroxide to oxide ratio led to different adsorption kinetics of the phosphonic acid from dilute ethanol solutions as measured by means of a quartz crystal microbalance. Water plasma treatment caused a significant increase in the density of surface hydroxyl groups in comparison to that of the argon-plasma-treated surface. The hydroxyl-rich surface led to significantly accelerated adsorption kinetics of the phosphonic acid with a time of monolayer formation of less than 1 min. On the contrary, decreasing the surface hydroxyl density slowed the adsorption kinetics.

  13. Conformational mechanics, adsorption, and normal force interactions of lubricin and hyaluronic acid on model surfaces.

    Science.gov (United States)

    Chang, Debby P; Abu-Lail, Nehal I; Guilak, Farshid; Jay, Gregory D; Zauscher, Stefan

    2008-02-19

    Glycoproteins, such as lubricin, and hyaluronic acid (HA) play a prominent role in the boundary lubrication mechanism in diarthrodial joints. Although many studies have tried to elucidate the lubrication mechanisms of articular cartilage, the molecular details of how lubricin and HA interact with cartilage surfaces and mediate their interaction still remain poorly understood. Here we used model substrates, functionalized with self-assembled monolayers terminating in hydroxyl or methyl groups, (1) to determine the effect of surface chemistry on lubricin and HA adsorption using surface plasmon resonance (SPR) and (2) to study normal force interactions between these surfaces as a function of lubricin and HA concentration using colloidal probe microscopy. We found that lubricin is amphiphilic and adsorbed strongly onto both methyl- and hydroxyl-terminated surfaces. On hydrophobic surfaces, lubricin likely adopts a compact, looplike conformation in which its hydrophobic domains at the N and C termini serve as surface anchors. On hydrophilic surfaces, lubricin likely adsorbs anywhere along its hydrophilic central domain and adopts, with increasing solution concentration, an extended tail-like conformation. Overall, lubricin develops strong repulsive interactions when compressing two surfaces into contact. Furthermore, upon surface separation, adhesion occurs between the surfaces as a result of molecular bridging and chain disentanglement. This behavior is in contrast to that of HA, which does not adsorb appreciably on either of the model surfaces and does not develop significant repulsive interactions. Adhesive forces, particularly between the hydrophobic surfaces, are large and not appreciably affected by HA. For a mixture of lubricin and HA, we observed slightly larger adsorptions and repulsions than those found for lubricin alone. Our experiments suggest that this interaction depends on unspecific physical rather than chemical interactions between lubricin and HA. We

  14. Gold Nanoplates for a Localized Surface Plasmon Resonance-Based Boric Acid Sensor.

    Science.gov (United States)

    Morsin, Marlia; Mat Salleh, Muhamad; Ali Umar, Akrajas; Sahdan, Mohd Zainizan

    2017-04-25

    Localized surface plasmon resonance (LSPR) properties of metallic nanostructures, such as gold, are very sensitive to the dielectric environment of the material, which can simply be adjusted by changing its shape and size through modification of the synthesizing process. Thus, these unique properties are very promising, particularly for the detection of various types of chemicals, for example boric acid which is a non-permitted preservative employed in food preparations. For the sensing material, gold (Au) nanoplates with a variety of shapes, i.e., triangular, hexagonal, truncated pentagon and flat rod, were prepared using a seed-mediated growth method. The yield of Au nanoplates was estimated to be ca. 63% over all areas of the sensing material. The nanoplates produced two absorption bands, i.e., the transverse surface plasmon resonance (t-SPR) and the longitudinal surface plasmon resonance (l-SPR) at 545 nm and 710 nm, respectively. In the sensing study, these two bands were used to examine the response of gold nanoplates to the presence of boric acid in an aqueous environment. In a typical process, when the sample is immersed into an aqueous solution containing boric acid, these two bands may change their intensity and peak centers as a result of the interaction between the boric acid and the gold nanoplates. The changes in the intensities and peak positions of t-SPR and l-SPR linearly correlated with the change in the boric acid concentration in the solution.

  15. MUTAGENICITY AND DISINFECTION BY-PRODUCTS IN SURFACE DRINKING WATER DISINFECTED WITH PERACETIC ACID

    Science.gov (United States)

    The aims of this research were to study the influence of peracetic acid (PAA) on the formation of mutagens in surface waters used for human consumption and to assess its potential application for the disinfection of drinking water. The results obtained using PAA were compared to ...

  16. Simultaneous saccharification and ethanol fermentation of oxalic acid pretreated corncob assessed with response surface methodology

    Science.gov (United States)

    Jae-Won Lee; Rita C.L.B. Rodrigues; Thomas W. Jeffries

    2009-01-01

    Response surface methodology was used to evaluate optimal time, temperature and oxalic acid concentration for simultaneous saccharification and fermentation (SSF) of corncob particles by Pichia stipitis CBS 6054. Fifteen different conditions for pretreatment were examined in a 23 full factorial design with six axial points. Temperatures ranged from 132 to 180º...

  17. Interaction of multi-walled carbon nanotubes with perfluorinated sulfonic acid ionomers and surface treatment studies

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Borghei, Maryam

    2014-01-01

    The interaction between high surface area nano-carbon catalyst supports for proton exchange membrane fuel cells (PEMFCs) and perfluorinated sulfonic acid (Nafion®) ionomer was studied 19 fluorine nuclear magnetic resonance spectroscopy (19F-NMR). The method was developed and improved for more...

  18. Electrochemical surface modification technique to impede mild steel corrosion using perfluorooctanoic acid

    Directory of Open Access Journals (Sweden)

    Shubha H Natarj

    2016-02-01

    Full Text Available The present work demonstrated that corrosion inhibition efficiency of electrochemically generated organic coat is remarkably effective than self-assembled monolayer (SAM generated by dip coating technique. Perfluorooctanoic Acid (PFOA is used to modify mild steel surface for effective protection. Infrared reflection absorption spectroscopy and contact angle measurements substantiate the modification of mild steel surface and its effect on surface hydrophobicity. A comparison between electrochemical properties of PFOA SAM generated by dip coat method (DC-PFOA and PFOA coat generated by electrochemical method (EC-PFOA is presented. Electrochemical measurements reveal that the corrosion protection efficiency of EC-PFOA (91% is much superior to DC-PFOA (28%.

  19. Infrared Spectroscopic Evidence of Surface Speciation of Amino Acids on Titanium Dioxide

    Science.gov (United States)

    Jonsson, C. M.; Jonsson, C. L.; Parikh, S. J.; Sverjensky, D. A.; Cleaves, H. J.; Hazen, R. M.

    2008-12-01

    Interactions that occur at the interface between molecules and mineral surfaces in the presence of water are integral to many chemical and physical processes, including the behavior of pollutants in the environment, metal implants in the human body, and perhaps the origin of life. During the emergence of life, mineral surfaces may have played a role in the selection of amino acids, leading to the formation of proteins that are essential building blocks of life. To investigate this hypothesis, we are studying two amino acids, glutamic (Glu) and aspartic (Asp) acid, and their adsorption to the rutile form of titanium dioxide as a function of pH and surface coverage in electrolyte solutions. The objective is to get a fundamental understanding of the speciation and coordination chemistry of these amino acids at the rutile surface. We used attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy to investigate the adsorption of Glu on rutile, and a previously published ATR-FTIR study [1] of Asp and Glu adsorption on an amorphous titanium dioxide film was used as a guide to peak assignment and interpretation of our FTIR spectra. Binding of Glu to both surfaces occurs primarily through one or both of the carboxyl groups, implying that at least two types of surface complexes are formed in a proportion presumably dependent on surface coverage and pH. The interpretation of our results suggests that Glu binds to rutile in a mixed chelating-monodentate fashion involving both carboxyl groups (Glu lying down at the surface), and in a chelating fashion involving only the gamma carboxyl group (Glu standing up at the surface). FTIR results also show that the intensity of the amine peak increases with sorption, which is possibly a consequence of the amine group being brought closer to the surface but not binding directly to it. Glu adsorption on rutile is favored at low pH, based on results from batch adsorption experiments. We have commenced a systematic

  20. Surface Lewis acid-base properties of polymers measured by inverse gas chromatography.

    Science.gov (United States)

    Shi, Baoli; Zhang, Qianru; Jia, Lina; Liu, Yang; Li, Bin

    2007-05-18

    Surface Lewis acid-base properties are significant for polymers materials. The acid constant, K(a) and base constant, K(b) of many polymers were characterized by some researchers with inverse gas chromatography (IGC) in recent years. In this paper, the surface acid-base constants, K(a) and K(b) of 20 kinds of polymers measured by IGC in recent years are summarized and discussed, including seven polymers characterized in this work. After plotting K(b) versus K(a), it is found that the polymers can be encircled by a triangle. They scatter in two regions of the triangle. Four polymers exist in region I. K(b)/K(a) of the polymers in region I are 1.4-2.1. The other polymers exist in region II. Most of the polymers are relative basic materials.

  1. Surface properties of pillared acid-activated bentonite as catalyst for selective production of linear alkylbenzene

    Science.gov (United States)

    Faghihian, Hossein; Mohammadi, Mohammad Hadi

    2013-01-01

    Acid-activated and pillared montmorillonite were prepared as novel catalysts for alkylation of benzene with 1-decene for production of linear alkylbenzene. The catalysts were characterized by X-ray diffraction, FT-IR spectroscopy, N2 adsorption isotherms, temperature programmed desorption of NH3, scanning electron microscopy and elemental and thermal analysis techniques. It was found that acid-activation of clays prior to pillaring increased the porosity, total specific surface area, total pore volume and surface acidity of the catalysts. Optimization of the reaction conditions was performed by varying catalyst concentration (0.25-1.75 wt%), reactants ratio (benzene to 1-decene of 8.75, 12 and 15) and temperature (115-145 °C) in a batch slurry reactor. Under optimized conditions more than 98% conversion of 1-decene, and complete selectivity for monoalkylbenzenes were achieved.

  2. Biocatalyzed approach for the surface functionalization of poly(L-lactic acid) films using hydrolytic enzymes.

    Science.gov (United States)

    Pellis, Alessandro; Acero, Enrique Herrero; Weber, Hansjoerg; Obersriebnig, Michael; Breinbauer, Rolf; Srebotnik, Ewald; Guebitz, Georg M

    2015-09-01

    Poly(lactic acid) as a biodegradable thermoplastic polyester has received increasing attention. This renewable polyester has found applications in a wide range of products such as food packaging, textiles and biomedical devices. Its major drawbacks are poor toughness, slow degradation rate and lack of reactive side-chain groups. An enzymatic process for the grafting of carboxylic acids onto the surface of poly(L-lactic acid) (PLLA) films was developed using Candida antarctica lipase B as a catalyst. Enzymatic hydrolysis of the PLLA film using Humicola insolens cutinase in order to increase the number of hydroxyl and carboxylic groups on the outer polymer chains for grafting was also assessed and showed a change of water contact angle from 74.6 to 33.1° while the roughness and waviness were an order of magnitude higher in comparison to the blank. Surface functionalization was demonstrated using two different techniques, (14) C-radiochemical analysis and X-ray photoelectron spectroscopy (XPS) using (14) C-butyric acid sodium salt and 4,4,4-trifluorobutyric acid as model molecules, respectively. XPS analysis showed that 4,4,4-trifluorobutyric acid was enzymatically coupled based on an increase of the fluor content from 0.19 to 0.40%. The presented (14) C-radiochemical analyses are consistent with the XPS data indicating the potential of enzymatic functionalization in different reaction conditions.

  3. Surface Tension of Acid Solutions: Fluctuations beyond the Nonlinear Poisson-Boltzmann Theory.

    Science.gov (United States)

    Markovich, Tomer; Andelman, David; Podgornik, Rudi

    2017-01-10

    We extend our previous study of surface tension of ionic solutions and apply it to acids (and salts) with strong ion-surface interactions, as described by a single adhesivity parameter for the ionic species interacting with the interface. We derive the appropriate nonlinear boundary condition with an effective surface charge due to the adsorption of ions from the bulk onto the interface. The calculation is done using the loop-expansion technique, where the zero loop (mean field) corresponds of the full nonlinear Poisson-Boltzmann equation. The surface tension is obtained analytically to one-loop order, where the mean-field contribution is a modification of the Poisson-Boltzmann surface tension and the one-loop contribution gives a generalization of the Onsager-Samaras result. Adhesivity significantly affects both contributions to the surface tension, as can be seen from the dependence of surface tension on salt concentration for strongly absorbing ions. Comparison with available experimental data on a wide range of different acids and salts allows the fitting of the adhesivity parameter. In addition, it identifies the regime(s) where the hypotheses on which the theory is based are outside their range of validity.

  4. Improvement of β-TCP/PLLA biodegradable material by surface modification with stearic acid.

    Science.gov (United States)

    Ma, Fengcang; Chen, Sai; Liu, Ping; Geng, Fang; Li, Wei; Liu, Xinkuan; He, Daihua; Pan, Deng

    2016-05-01

    Poly-L-lactide (PLLA) is a biodegradable polymer and used widely. Incorporation of beta tricalcium phosphate (β-TCP) into PLLA can enhance its osteoinductive properties. But the interfacial layer between β-TCP particles with PLLA matrix is easy to be destroyed due to inferior interfacial compatibility of the organic/inorganic material. In this work, a method of β-TCP surface modification with stearic acid was investigated to improve the β-TCP/PLLA biomaterial. The effects of surface modification on the β-TCP were investigated by FTIR, XPS, TGA and CA. It was found that the stearic acid reacted with β-TCP and oxhydryl was formed during the surface modification. Hydrophilicity of untreated or modified β-TCP/PLLA composite was increased by the addition of 10 wt.% β-TCP, but it decreased as the addition amount increased from 10 wt.% to 20 wt.%. Two models were suggested to describe the effect of β-TCP concentration on CA of the composites. Mechanical properties of β-TCP/PLLA composites were tested by bending and tensile tests. Fractures of the composites after mechanical test were observed by SEM. It was found that surface modification with stearic acid improved bending and tensile strengths of the β-TCP/PLLA composites obviously. The SEM results indicated that surface modification decreased the probability of interface debonding between fillers and matrix under load.

  5. Natural and pyrogenic humic acids at goethite and natural oxide surfaces interacting with phosphate.

    Science.gov (United States)

    Hiemstra, Tjisse; Mia, Shamim; Duhaut, Pierre-Benoît; Molleman, Bastiaan

    2013-08-20

    Fulvic and humic acids have a large variability in binding to metal (hydr) oxide surfaces and interact differently with oxyanions, as examined here experimentally. Pyrogenic humic acid has been included in our study since it will be released to the environment in the case of large-scale application of biochar, potentially creating Darks Earths or Terra Preta soils. A surface complexation approach has been developed that aims to describe the competitive behavior of natural organic matter (NOM) in soil as well as model systems. Modeling points unexpectedly to a strong change of the molecular conformation of humic acid (HA) with a predominant adsorption in the Stern layer domain at low NOM loading. In soil, mineral oxide surfaces remain efficiently loaded by mineral-protected organic carbon (OC), equivalent with a layer thickness of ≥ ~0.5 nm that represents at least 0.1-1.0% OC, while surface-associated OC may be even three times higher. In natural systems, surface complexation modeling should account for this pervasive NOM coverage. With our charge distribution model for NOM (NOM-CD), the pH-dependent oxyanion competition of the organo-mineral oxide fraction can be described. For pyrogenic HA, a more than 10-fold increase in dissolved phosphate is predicted at long-term applications of biochar or black carbon.

  6. Acid Aging Effects on Surfaces of PTFE Gaskets Investigated by Thermal Analysis

    Directory of Open Access Journals (Sweden)

    C. Fragassa

    2016-12-01

    Full Text Available This paper investigates the effect of a prolonged acid attack on the surface of PTFE by Thermogravimetric Analysis (TGA and Differential Scanning Calorimetry (DSC. PTFE is very non-reactive, partly because of the strength of carbon–fluorine bonds and for its high crystallinity, and, as a consequence, it is often used in containers and pipework with reactive and corrosive chemicals. The PTFE under analysis is commercialized by two alternative producers in form of Teflon tapes. These tapes are adopted, as gaskets, in process plants where tires moulds are cleaned by acid solutions inside a multistage ultrasonic process. In this case, PTFE shows, in a relatively short operation time, inexplicably phenomena of surface degradation, which could be related, in general terms, to an acid attack. But, even considering the combined effect of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the risk of the extreme erosion phenomena as observed. The present experimental research aim at investigating this contradiction. A possible explanation could be related to the presence in the cleaning solution of unexpected fluorides, able to produce fluorinating agents and, thus, degrade carbon-fluorine bonds. Considering more the 300 chemical elements a tire compound consists in, it is really complex to preserve the original chemical composition of the cleaning solution. In this research PTFE samples have been treated with different mixtures of acids with the aim at investigating the different aging effects. The thermal analysis has permitted the experimental characterization of PTFE surface properties after acid attack, providing evidence of the degradation phenomena. In particular, the different acid treatments adopted for accelerating the aging of gaskets have highlighted the different behaviour of the PTFE matrix, but also differences between manufacturers.

  7. CHOLESTERIC LIQUID CRYSTALLINE CHARACTER ON THE SURFACE OF CHITOSAN/POLYACRYLIC ACID COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Yan-ming Dong; Yu-song; Wu Mian Wang

    2001-01-01

    The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surface techniques. A periodical lamellar-like structure was observed in the permanganic acid etched film surface by both scanning electron microscopy (SEM) and atomic force microscopy (AFM), instead of the thumb-print texture which can be detected with polarized optical microscopy. It is suggested that the periodical lamellar-like structure is induced by the etching selectivity between cholesteric layers due to different molecular arrangement on the film surface. Four kinds of perpendicular disclinations, I.e. Χ→τ- + λ+, χ→λ- + τ+, χ→τ- + τ+ and χ→λ- + λ+, were found in the composite films from SEM observations. The smallest periodicity of lamellar-like structure (equals to halfpitch) is 20~40 nm measured with AFM.

  8. Modelling of the simultaneous photodegradation of Acid Red 97, Acid Orange 61 and Acid Brown 425 using factor screening and response surface strategies.

    Science.gov (United States)

    Fernández, Cristina; Larrechi, M Soledad; Callao, M Pilar

    2010-08-15

    In this paper the influence of seven variables that could be relevant in the photodegradation of three textile dyes - Acid Red 97, Acid Orange 61 and Acid Brown 425 - has been studied with the aim of determining the most efficient conditions for this process. The type and concentration of catalyst, the presence and concentration of H(2)O(2), the stirring, the pH and the dye concentration have been studied as variables. In the first stage the more basic variables were analyzed using a screening methodology (saturated fractional factorial design) and it was concluded that the most influential variable was the presence of H(2)O(2). In the second stage, a central composite design was used to establish a response surface for the behavior of the photodegradation. In this stage the concentration of Acid Brown 425 was fixed and the degradation was carried out without catalyst. The most remarkable aspects of the experiment are that brown dye is always the most persistent in the solution and that a catalyst is not needed to degrade the dyes quickly. A second-order equation is needed to model this process. The response surface obtained could be useful for reducing the time and money needed to treat effluent wastewater. Copyright 2010 Elsevier B.V. All rights reserved.

  9. Enhanced lubrication on tissue and biomaterial surfaces through peptide-mediated binding of hyaluronic acid.

    Science.gov (United States)

    Singh, Anirudha; Corvelli, Michael; Unterman, Shimon A; Wepasnick, Kevin A; McDonnell, Peter; Elisseeff, Jennifer H

    2014-10-01

    Lubrication is key for the efficient function of devices and tissues with moving surfaces, such as articulating joints, ocular surfaces and the lungs. Indeed, lubrication dysfunction leads to increased friction and degeneration of these systems. Here, we present a polymer-peptide surface coating platform to non-covalently bind hyaluronic acid (HA), a natural lubricant in the body. Tissue surfaces treated with the HA-binding system exhibited higher lubricity values, and in vivo were able to retain HA in the articular joint and to bind ocular tissue surfaces. Biomaterials-mediated strategies that locally bind and concentrate HA could provide physical and biological benefits when used to treat tissue-lubricating dysfunction and to coat medical devices.

  10. Enhanced lubrication on tissue and biomaterial surfaces through peptide-mediated binding of hyaluronic acid

    Science.gov (United States)

    Singh, Anirudha; Corvelli, Michael; Unterman, Shimon A.; Wepasnick, Kevin A.; McDonnell, Peter; Elisseeff, Jennifer H.

    2014-10-01

    Lubrication is key for the efficient function of devices and tissues with moving surfaces, such as articulating joints, ocular surfaces and the lungs. Indeed, lubrication dysfunction leads to increased friction and degeneration of these systems. Here, we present a polymer-peptide surface coating platform to non-covalently bind hyaluronic acid (HA), a natural lubricant in the body. Tissue surfaces treated with the HA-binding system exhibited higher lubricity values, and in vivo were able to retain HA in the articular joint and to bind ocular tissue surfaces. Biomaterials-mediated strategies that locally bind and concentrate HA could provide physical and biological benefits when used to treat tissue-lubricating dysfunction and to coat medical devices.

  11. Heterologous surface display on lactic acid bacteria: non-GMO alternative?

    Science.gov (United States)

    Zadravec, Petra; Štrukelj, Borut; Berlec, Aleš

    2015-01-01

    Lactic acid bacteria (LAB) are food-grade hosts for surface display with potential applications in food and therapy. Alternative approaches to surface display on LAB would avoid the use of recombinant DNA technology and genetically-modified organism (GMO)-related regulatory requirements. Non-covalent surface display of proteins can be achieved by fusing them to various cell-wall binding domains, of which the Lysine motif domain (LysM) is particularly well studied. Fusion proteins have been isolated from recombinant bacteria or from their growth medium and displayed on unmodified bacteria, enabling heterologous surface display. This was demonstrated on non-viable cells devoid of protein content, termed bacteria-like particles, and on various species of genus Lactobacillus. Of the latter, Lactobacillus salivarius ATCC 11741 was recently shown to be particularly amenable for LysM-mediated display. Possible regulatory implications of heterologous surface display are discussed, particularly those relevant for the European Union.

  12. Reactive Separation of Gallic Acid: Experimentation and Optimization Using Response Surface Methodology and Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    K. Rewatkar

    2017-04-01

    Full Text Available Gallic acid is a major phenolic pollutant present in the wastewater generated from cork boiling, olive mill, and pharmaceutical industries. Experimental and statistical modelling using response surface methodology (RSM and artificial neural network (ANN were carried out for reactive separation of gallic acid from aqueous stream using tri-nbutyl phosphate (TBP in hexanol. TBP has a more significant effect on extraction efficiency as compared to temperature and pH. The optimum conditions of 2.34 g L–1, 65.65 % v/v, 19 oC, and 1.8 of initial concentration of gallic acid, concentration of TBP, temperature, and pH, respectively, were obtained using RSM. Under optimum conditions, extraction efficiency of 99.45 % was obtained for gallic acid. The ANN and RSM results were compared with experimental unseen data. Error analysis suggested the better performance of ANN for extraction efficiency predictions.

  13. Structure and property of multiple amino acids assembled on the surface of a CNT

    Science.gov (United States)

    Wang, Cuihong; Yang, Guangwu; Jiang, Yue

    2017-01-01

    Amino acids were placed with maximal filling on the surface of a CNT via hydrogen bonding and H/π interactions. The interaction structures and properties of assembled complexes were investigated via the density functional tight-binding method. The structural parameters and interaction energies were analyzed to identify the weak interaction strengths. We found that the H/π interactions between amino acids and CNTs play more important roles than the hydrogen bonds between amino acids in stabilizing the complex structures. The effect of CNT chirality and amino acid type were also studied. Furthermore, the HOMOs and LUMOs of the representative complexes were also studied to illustrate the interactions. Our data is helpful in the modification of CNTs by biomolecules.

  14. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

    Energy Technology Data Exchange (ETDEWEB)

    Boszormenyi, I.

    1991-05-01

    This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

  15. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

    Energy Technology Data Exchange (ETDEWEB)

    Boszormenyi, I.

    1991-05-01

    This (<100 {Angstrom}) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 {times} r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm{sup 2} catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on ``Pt-on-alumina`` and on ``alumina-on-Pt`` are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

  16. Chemical modification of chitosan film via surface grafting of citric acid molecular to promote the biomineralization

    Science.gov (United States)

    Liu, Yang; Shen, Xin; Zhou, Huan; Wang, Yingjun; Deng, Linhong

    2016-05-01

    We develop a novel chitosan-citric acid film (abbreviated as CS-CA) suitable for biomedical applications in this study. In this CS-CA film, the citric acid, which is a harmless organic acid has been extensively investigated as a modifying agent on carbohydrate polymers, was cross-linked by 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) onto the surface of chitosan (CS) film. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirms the graft copolymerization of the modified chitosan film (CS-CA). Surface wettability, moisturizing performance, the capacity of mineralization in vitro and biocompatibility of the films were characterized. After modification, this CS-CA film has good hydrophilicity. It is very evident that the citric acid grafting treatment significantly promotes the biomineralization of the chitosan based substrates. Cell experiments show that the MC3T3-E1 osteoblasts can adhere and proliferate well on the surface of CS-CA film. This CS-CA film, which can be prepared in large quantities and at low cost, should have potential application in bone tissue engineering.

  17. Evaluation of flowable resin composite surfaces eroded by acidic and alcoholic drinks.

    Science.gov (United States)

    Han, Linlin; Okamoto, Akira; Fukushima, Masayoshi; Okiji, Takashi

    2008-05-01

    The purpose of this study was to evaluate the morphological changes of the surfaces of flowable resins eroded by orange juice and alcohol drinks. The tested products were Beautifil Flow BF02 and BF10, Clearfil Majesty LV, Filtek Supreme XT Flowable Restorative, Unifil LoFlo Plus and Filtek Supreme. Filler percentages of flowable resins were calculated after the latter were incinerated at 750 degrees C. Specimens were shaped into a disk form with a diameter of 10 mm and a thickness of 1 mm. Morphological changes were evaluated for the following types of flowable resin surfaces: polished surface, surfaces eroded by 100% orange juice, wine and whisky. Filler percentages of the tested flowable resins ranged between 42 and 78%. Surface degradation was observed for the specimens immersed in acidic and alcoholic drinks, and it was thought that the lower the filler percentage, the greater was the surface degradation. Decomposition of the matrix resin and fallout of the fillers were observed in flowable resins that eroded with acidic and alcoholic drinks.

  18. Simple coupling chemistry linking carboxyl-containing organic molecules to silicon oxide surfaces under acidic conditions.

    Science.gov (United States)

    Schmidt, Sebastian W; Christ, Timo; Glockner, Christian; Beyer, Martin K; Clausen-Schaumann, Hauke

    2010-10-05

    The coupling chemistry of carboxymethylated amylose with organo-silanized silicon oxide surfaces at pH 7.4 and 2.0 was investigated using atomic force microscopy (AFM) based single-molecule force spectroscopy. At close to neutral pH, carbodiimide activation of a carboxylic acid affords formation of an amide bond with an amino surface linker. At pH 2.0, no activation with carbodiimide was required to anchor carboxymethylated amylose between an AFM tip and a glass substrate. At the same time, the mean bond rupture force f(r) dropped from 1.65 ± 0.37 nN at pH 7.4 to 1.39 ± 0.30 nN at pH 2.0 without carbodiimide, indicating that a different link to the surface can be formed at low pH. The coupling mechanism at pH 2.0 was elucidated by a series of experiments, in which the surface was functionalized with four different organosilanes, each containing characteristic functional groups. The results are rationalized with an acid-catalyzed ester condensation between a carboxyl group and a free, unreacted silanol group in the surface anchor or on the surface.

  19. Unravelling the surface chemistry of metal oxide nanocrystals, the role of acids and bases.

    Science.gov (United States)

    De Roo, Jonathan; Van den Broeck, Freya; De Keukeleere, Katrien; Martins, José C; Van Driessche, Isabel; Hens, Zeger

    2014-07-09

    We synthesized HfO2 nanocrystals from HfCl4 using a surfactant-free solvothermal process in benzyl alcohol and found that the resulting nanocrystals could be transferred to nonpolar media using a mixture of carboxylic acids and amines. Using solution (1)H NMR, FTIR, and elemental analysis, we studied the details of the transfer reaction and the surface chemistry of the resulting sterically stabilized nanocrystals. As-synthesized nanocrystals are charge-stabilized by protons, with chloride acting as the counterion. Treatment with only carboxylic acids does not lead to any binding of ligands to the HfO2 surface. On the other hand, we find that the addition of amines provides the basic environment in which carboxylic acids can dissociate and replace chloride. This results in stable, aggregate-free dispersions of HfO2 nanocrystals, sterically stabilized by carboxylate ligands. Moreover, titrations with deuterated carboxylic acid show that the charge on the carboxylate ligands is balanced by coadsorbed protons. Hence, opposite from the X-type/nonstoichiometric nanocrystals picture prevailing in literature, one should look at HfO2/carboxylate nanocrystals as systems where carboxylic acids are dissociatively adsorbed to bind to the nanocrystals. Similar results were obtained with ZrO2 NCs. Since proton accommodation on the surface is most likely due to the high Brønsted basicity of oxygen, our model could be a more general picture for the surface chemistry of metal oxide nanocrystals with important consequences on the chemistry of ligand exchange reactions.

  20. Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations.

    Science.gov (United States)

    Bona, Alvaro Della; Pinzetta, Caroline; Rosa, Vinícius

    2007-06-01

    The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE - conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24 degrees C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05). Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

  1. Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations

    Directory of Open Access Journals (Sweden)

    Álvaro Della Bona

    2007-06-01

    Full Text Available The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth, assigned to 4 groups (n=10 and restored as follows: Group CIE - conventional GIC (CI was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC; Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24ºC for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05. Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

  2. Paleoproterozoic anorogenic granitoids of the Zheltav sialic massif (Southern Kazakhstan): Structural position and geochronology

    Science.gov (United States)

    Tretyakov, A. A.; Degtyarev, K. E.; Sal'nikova, E. B.; Shatagin, K. N.; Kotov, A. B.; Ryazantsev, A. V.; Pilitsyna, A. V.; Yakovleva, S. Z.; Tolmacheva, E. V.; Plotkina, Yu. V.

    2016-01-01

    The basement of the Zheltav sialic massif (Southern Kazakhstan) is composed of different metamorphic rocks united into the Anrakhai Complex. In the southeastern part of the massif, these rocks form a large antiform with the core represented by amphibole and clinopyroxene gneissic granite varieties. By their chemical composition, dominant amphibole (hastingsite) gneissic granites correspond to subalkaline granites, while their petroand geochemical properties make them close to A-type granites. The U-Pb geochronological study of accessory zircons yielded an age of 1841 ± 6 Ma, which corresponds to the crystallization age of melts parental for protoliths of amphibole gneissic granites of the Zheltav Massif. Thus, the structural-geological and geochronological data make it possible to define the Paleoproterozoic (Staterian) stage of anorogenic magmatism in the Precambrian history of the Zheltav Massif. The combined Sm-Nd isotopic—geochronological data and age estimates obtained for detrital zircons indicate the significant role of the Paleoproterozoic tectono-magmatic stage in the formation of the Precambrian continental crust of sialic massifs in Kazakhstan and northern Tien Shan.

  3. FRACTAL ANALYSIS OF PHYSICAL ADSORPTION ON SURFACES OF ACID ACTIVATED BENTONITES FROM SERBIA

    Directory of Open Access Journals (Sweden)

    Ljiljana Rožić

    2008-11-01

    Full Text Available Solid surfaces are neither ideally regular, that is, morphological and energeticcally homogeneous, nor are they fully irregular or fractal. Instead, real solid surfaces exhibit a limited degree of organization quantified by the fractal dimension, D. Fractal analysis was applied to investigate the effect of concentrations of HCl solutions on the structural and textural properties of chemically activated bentonite from southern Serbia. Acid treatment of bentonites is applied in order to remove impurities and various exchangeable cations from bentonite clay. Important physical changes in acid-activated smectite are the increase of the specific surface area and of the average pore volume, depending on acid strength, time and temperature of a treatment. On the basis of the sorption-structure analysis, the fractal dimension of the bentonite surfaces was determined by Mahnke and Mögel method. The fractal dimension evaluated by this method was 2.11 for the AB3 and 1.94 for the AB4.5 sample. The estimation of the values of the fractal dimension of activated bentonites was performed in the region of small pores, 0.5 nm < rp < 2 nm.

  4. Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

    Science.gov (United States)

    2010-06-17

    Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America, 5 Department of Parasitology , Division of Experimental... parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of...Sciences, Bethesda, MD, ...... 14. ABSTRACT Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is

  5. Requirement for sialic acid on the endothelial ligand of a lymphocyte homing receptor

    OpenAIRE

    1990-01-01

    The entry of blood-borne lymphocytes into most secondary lymphoid organs is initiated by a highly specific adhesive interaction with the specialized cuboidal endothelial cells of high endothelial venules (HEV). The adhesive receptors on lymphocytes that dictate interactions with HEV in different lymphoid organs are called homing receptors, signifying their critical role in controlling organ-selective lymphocyte migration. Considerable work has established that the mouse peripheral lymph node ...

  6. Effect of type of alcoholic beverages on carbohydrate-deficient transferrin, sialic acid, and liver enzymes

    NARCIS (Netherlands)

    Sillanaukee, P.; Gaag, M.S. van der; Sierksma, A.; Hendriks, H.F.J.; Strid, N.; Pönniö, M.; Nikkari, S.T.

    2003-01-01

    Background: There are only limited data obtained under well controlled conditions on the effects of moderate drinking on markers of alcohol use disorders. The aim of this study was to investigate the effects of moderate intake of different alcoholic beverages on these markers, including carbohydrate

  7. Comparison of Dissolution and Surface Reactions Between Calcite and Aragonite in L-Glutamic and L-Aspartic Acid Solutions

    Directory of Open Access Journals (Sweden)

    Kwangsuk You

    2010-01-01

    Full Text Available We have investigated dissolution and surface reaction of calcite and aragonite in amino acid solutions of L-glutamic (L-glu and L-aspartic acid (L-asp at weak acidity of above pH 3. The surface reactions of calcite and aragonite were related with the dissolution. Calcite was dissolved in both solutions but the dissolution was limited by an adsorption of Ca-carboxylate salt. Aragonite was neither dissolved nor reacted in amino acid solutions because the crystal surface consisted of a hard to dissolve structure.

  8. Surface photografting of acrylic acid on poly(dimethylsiloxane). Experimental and dissipative particle dynamics studies.

    Science.gov (United States)

    Ramírez-Gutiérrez, David; Nieto-Draghi, Carlos; Pannacci, Nicolas; Castro, Laura V; Álvarez-Ramírez, Fernando; Creton, Benoit

    2015-02-03

    This work includes both experimental and theoretical studies of the wetting property changes of water on a surface of poly(dimethylsiloxane) (PDMS) modified with different amounts of acrylic acid (AA). The default surface properties of PDMS were changed from hydrophobic to hydrophilic behavior which was characterized with contact angle measurements by two approaches: (i) experimental tests of samples subjected to a photografting polymerization procedure to obtain a functionalized surface and (ii) DPD (dissipative particle dynamics) simulations which also involve the calculation of sets of repulsive parameters determined following two methods: the use of the "Blends" module in the Materials Studio software and the calculation of cohesive energy density with molecular simulations. Changes of contact angle values observed from both experimental and numerical simulation results provide qualitative and quantitative information on the wetting behavior of photografted surfaces.

  9. Yield of Fumaric Acid from Different Carbohydrates by Stationary Surface Culture Method

    Directory of Open Access Journals (Sweden)

    Km. Maya Saijwani

    1968-07-01

    Full Text Available Studies on the yield of fumaric acid by Rhizopus arrhizus and Bhizopus nigricans using glucose, sucrose, xylose,cane molassess and bagasse hydrolysate either alone or in combination with glucose were undertaken. Thirty three and 26 per cently yield of fumaric acid were obtained from 12 and 10 per cent glucose media respectively, in 15 days at 33 degree calcius by stationary surface culture method. Higher yields of fumaric acid were obtained from glucose using R. arrhizus. Ability of this organism to produce fumaric acid from media containing (i 50:50 glucose and deionized bagasse,hydrolysate (ii deionized bagasse hydrolysate, and (iii clarified cane molasses was investigated. A 7 per cent yield of fumaric acid was obtained from 50:50 glucose and deionized bagasse hydrolysate medium. In the case of xylose good growth of the fungus was obtained but no fumaric acid was produced. These studies have indicated that R. arrhizus is not able to utilize pentose sugars.

  10. 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.

  11. Molecular simulation insights on the in vacuo adsorption of amino acids on graphene oxide surfaces with varying surface oxygen densities

    Science.gov (United States)

    Rahmani, Farzin; Nouranian, Sasan; Mahdavi, Mina; Al-Ostaz, Ahmed

    2016-11-01

    In this fundamental study, a series of molecular dynamics simulations were performed in vacuo to investigate the energetics and select geometries of 20 standard amino acids (AAs) on pristine graphene (PG) and graphene oxide (GO) surfaces as a function of graphene surface oxygen density. These interactions are of key interest to graphene/biomolecular systems. Our results indicate that aromatic AAs exhibit the strongest total interactions with the PG surfaces due to π-π stacking. Tryptophan (Trp) has the highest aromaticity due to its indole side chain and, hence, has the strongest interaction among all AAs (-16.66 kcal/mol). Aliphatic, polar, and charged AAs show various levels of affinity to the PG sheets depending on the strength of their side chain hydrophobic interactions. For example, arginine (Arg) with its guanidinium side chain exhibits the strongest interaction with the PG sheets (-13.81 kcal/mol) following aromatic AAs. Also, glycine (Gly; a polar AA) has the weakest interaction with the PG sheets (-7.29 kcal/mol). When oxygen-containing functional groups are added to the graphene sheets, the π-π stacking in aromatic AAs becomes disrupted and perfect parallelism of the aromatic rings is lost. Moreover, hydrogen bonding and/or electrostatic interactions become more pronounced. Charged AAs exhibit the strongest interactions with the GO surfaces. In general, the AA-GO interactions increase with increasing surface oxygen density, and the effect is more pronounced at higher O/C ratios. This study provides a quantitative measure of AA-graphene interactions for the design and tuning of biomolecular systems suitable for biosensing, drug delivery, and gene delivery applications.

  12. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili, E-mail: ziliyu@scu.edu.cn

    2014-10-30

    Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO{sub 4}/HNO{sub 3}. • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO{sub 4}/HNO{sub 3} treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  13. Conjugation of Hyaluronic Acid onto Surfaces via the Interfacial Polymerization of Dopamine to Prevent Protein Adsorption.

    Science.gov (United States)

    Huang, Renliang; Liu, Xia; Ye, Huijun; Su, Rongxin; Qi, Wei; Wang, Libing; He, Zhimin

    2015-11-10

    A versatile, convenient, and cost-effective method that can be used for grafting antifouling materials onto different surfaces is highly desirable in many applications. Here, we report the one-step fabrication of antifouling surfaces via the polymerization of dopamine and the simultaneous deposition of anionic hyaluronic acid (HA) on Au substrates. The water contact angle of the Au surfaces decreased from 84.9° to 24.8° after the attachment of a highly uniform polydopamine (PDA)/HA hybrid film. The results of surface plasmon resonance analysis showed that the Au-PDA/HA surfaces adsorbed proteins from solutions of bovine serum albumin, lysozyme, β-lactoglobulin, fibrinogen, and soybean milk in ultralow or low amounts (4.8-31.7 ng/cm(2)). The hydrophilicity and good antifouling performance of the PDA/HA surfaces is attributable to the HA chains that probably attached onto their upper surface via hydrogen bonding between PDA and HA. At the same time, the electrostatic repulsion between PDA and HA probably prevents the aggregation of PDA, resulting in the formation of a highly uniform PDA/HA hybrid film with the HA chains (with a stretched structure) on the upper surface. We also developed a simple method for removing this PDA/HA film and recycling the Au substrates by using an aqueous solution of NaOH as the hydrolyzing agent. The Au surface remained undamaged, and a PDA/HA film could be redeposited on the surface, with the surface exhibiting good antifouling performance even after 10 such cycles. Finally, it was found that this grafting method is applicable to other substrates, including epoxy resins, polystyrene, glass, and steel, owing to the strong adhesion of PDA with these substrates.

  14. Influence of citric acid on the surface texture of glass ionomer restorative materials

    Directory of Open Access Journals (Sweden)

    Dappili SwamiRanga Reddy

    2014-01-01

    Full Text Available Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7. Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, ΅m of each specimen was measured using a surface profilometer (Taylor & Habson, UK. Data was analyzed using one-way analysis of variance (ANOVA and Tukey′s HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of

  15. Synthesis, surface characterization and optical properties of 3-thiopropionic acid capped ZnS:Cu nanocrystals

    Indian Academy of Sciences (India)

    Ashish Tiwari; S A Khan; R S Kher

    2011-08-01

    3-Thiopropionic acid (TPA) capped ZnS:Cu nanocrystals have been successfully synthesized by simple aqueous method. Powder X-ray diffraction (XRD) studies revealed the particle size to be 4.2 nm. Surface characterization of the nanocrystals by FTIR spectroscopy has been done and the structure for surface bound TPA based on spectral analysis was proposed. The optical studies were done using UV-VIS spectroscopy and particle size and diameter polydispersity index (DPI) were calculated. Photoluminescence (PL) spectrum reveals emission related to the transition from conduction band of ZnS to 2 level of Cu2+. Electron microscopy was also done by scanning electron microscopy (SEM).

  16. Acid-base and surface energy characterization of grafted polyethylene using inverse gas chromatography.

    Science.gov (United States)

    Uhlmann, Petra; Schneider, Steffen

    2002-09-06

    For a specific design of interfaces, i.e. in composites and blends, it is essential to know the surface thermodynamics of the components. Polyethylene grafted with maleic anhydride and maleic anhydride-styrene mixtures, respectively, was the component of interest of our investigations. Inverse gas chromatography (IGC) at infinite dilution was shown to be an appropriate method to evaluate the dispersive and acid-base surface characteristics although there is an influence of bulk absorption and morphology when performing IGC above the glass transition temperature of the polymer.

  17. The binding of phosphonic acids at aluminium oxide surfaces and correlation with passivation of aluminium flake.

    Science.gov (United States)

    Cooper, Rachel J; Camp, Philip J; Henderson, David K; Lovatt, Paul A; Nation, David A; Richards, Stuart; Tasker, Peter A

    2007-04-07

    Measurements of adsorption isotherms of a series of thirteen mono- and di-phosphonic acids have shown that these bind strongly to the surface of high surface area aluminium trihydroxide. The incorporation of such phosphonates into a suspension of aluminium flake in an aqueous medium, modelling the continuous phase of a water-based paint, greatly suppresses the evolution of hydrogen. Whilst strong binding of the phosphonate to aluminium oxides is an essential criterion for good passivation, other factors such as the hydrophobicity of the ligand are also important in suppressing hydrogen-evolution.

  18. New insight into photo-bromination processes in saline surface waters: The case of salicylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tamtam, Fatima; Chiron, Serge, E-mail: serge.chiron@msem.univ-montp2.fr

    2012-10-01

    It was shown, through a combination of field and laboratory observations, that salicylic acid can undergo photo-bromination reactions in sunlit saline surface waters. Laboratory-scale experiments revealed that the photochemical yields of 5-bromosalicylic acid and 3,5-dibromosalicylic acid from salicylic acid were always low (in the 4% range at most). However, this might be of concern since these compounds are potential inhibitors of the 20{alpha}-hydroxysteroid dehydrogenase enzyme, with potential implications in endocrine disruption processes. At least two mechanisms were involved simultaneously to account for the photo-generation of brominated substances. The first one might involve the formation of reactive brominated radical species (Br{center_dot}, Br{sub 2}{center_dot}{sup -}) through hydroxyl radical mediated oxidation of bromide ions. These ions reacted more selectively than hydroxyl radicals with electron-rich organic pollutants such as salicylic acid. The second one might involve the formation of hypobromous acid, through a two electron oxidation of bromine ions by peroxynitrite. This reaction was catalyzed by nitrite, since these ions play a crucial role in the formation of nitric oxide upon photolysis. This nitric oxide further reacts with superoxide radical anions to yield peroxynitrite and by ammonium through the formation of N-bromoamines, probably due to the ability of N-bromoamines to promote the aromatic bromination of phenolic compounds. Field measurements revealed the presence of salicylic acid together with 5-bromosalicylic and 3,5-dibromosalicylic acid in a brackish coastal lagoon, thus confirming the environmental significance of the proposed photochemically induced bromination pathways. -- Highlights: Black-Right-Pointing-Pointer Brominated derivatives of salicylic acid were detected in a brackish lagoon. Black-Right-Pointing-Pointer A photochemical pathway was hypothesized to account for bromination of salicylic acid. Black

  19. Surface characterisation of ethylene-propylene-diene rubber upon exposure to aqueous acidic solution

    DEFF Research Database (Denmark)

    Mitra, S.; Ghanbari-Siahkali, Afshin; Kingshott, P.

    2006-01-01

    but significantly different with respect to molar mass and the presence of long chain branching. Both rubbers contained 5-ethylidene-2-norbomene (ENB) as diene. Solution cast films of pure EPDM samples were exposed in two different acidic solutions, viz. chromosulphuric (Cr (VI)/H2SO4) and sulphuric acid (H2SO4....... Furthermore, 20% Cr (VI)/H2SO4 also attacked the allylic carbon-hydrogen (C-H) bonds of ENB resulting in more oxygenated species on the surface compared to 20% H2SO4 under identical conditions. Cr (VI) in the 20% Cr (VI)/H2SO4 was found to play an important role in alteration of surface chemistry. Studies...

  20. Modelling and Statistical Optimization of Dilute Acid Hydrolysis of Corn Stover Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Andrew Nosakhare Amenaghawon

    2014-07-01

    Full Text Available Response surface methodology (RSM was employed for the analysis of the simultaneous effect of acid concentration, pretreatment time and temperature on the total reducing sugar concentration obtained during acid hydrolysis of corn stover. A three-variable, three-level Box-Behnken design (BBD was used to develop a statistical model for the optimization of the process variables. The optimal hydrolysis conditions that resulted in the maximum total reducing sugar concentration were acid concentration; 1.72 % (w/w, temperature; 169.260C and pretreatment time; 48.73 minutes. Under these conditions, the total reducing sugar concentration was obtained to be 23.41g/L. Validation of the model indicated no difference between predicted and observed values.

  1. Monitoring and assessment of surface water acidification following rewetting of oxidised acid sulfate soils.

    Science.gov (United States)

    Mosley, Luke M; Zammit, Benjamin; Jolley, Ann-Marie; Barnett, Liz; Fitzpatrick, Rob

    2014-01-01

    Large-scale exposure of acid sulfate soils during a hydrological drought in the Lower Lakes of South Australia resulted in acidification of surface water in several locations. Our aim was to describe the techniques used to monitor, assess and manage these acidification events using a field and laboratory dataset (n = 1,208) of acidic to circum-neutral pH water samples. The median pH of the acidified (pH  H(+) ≈ Mn(II) > Fe(II/III)) but was about 20 % higher on average. Geochemical speciation calculations and XRD measurements indicated that solid phase minerals (schwertmannite and jarosite for Fe and jurbanite for Al) were likely controlling dissolved metal concentrations and influencing measured acidity between pH 2 and 5.

  2. Effect of glutamic acid on copper sorption onto kaolinite. Batch experiments and surface complexation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Karimzadeh, Lotfallah; Barthen, Robert; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactive Transport; Stockmann, Madlen [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    In this work, we study the mobility behavior of Cu(II) under conditions related to an alternative, neutrophile biohydrometallurgical Cu(II) leaching approach. Sorption of copper onto kaolinite influenced by glutamic acid (Glu) was investigated in the presence of 0.01 M NaClO{sub 4} by means of binary and ternary batch adsorption measurements over a pH range of 4 to 9 and surface complexation modeling.

  3. Treatment process for a surface-active nitric acid solution used for rinsing nuclear installations

    Energy Technology Data Exchange (ETDEWEB)

    Celles, Caroline; Bisel, Isabelle; Gastaldi, Michel; Rudloff, David [CEA Valrho/DEN/VRH/DRCP/SCPS/LPCP, BP 17171, Bagnols sur Ceze cedex, 30207 (France)

    2008-07-01

    Full text of publication follows: The rinsing of the nuclear fuel reprocessing plants before their final shut-down and their dismantling is considered by the use of surface-active compounds in nitric acid medium. Before being vitrified, this solution must be mineralized and concentrated. Two treatments ways have been studied: The first was to act a direct concentration followed up by a mineralization through the Fenton reaction. The second way proposed to begin with the mineralization followed up by a concentration with denitration. The second way was not kept since laboratory tests showed organic phase demixion in distillate which is difficult to manage in industrial plants. The study presents the performance Fenton reaction with a new surface-active solution. In order to be representative of real solution in these nuclear installations to rinse, some hypothesis have been established concerning cations and TBP concentrations, likely to be present in the installation. Influences of parameters like temperature, the nature of the Fenton catalyst, the catalyst concentration, and the concentration of surface-active species were tested. The study highlight the kinetics of the mineralization, the H{sub 2}O{sub 2} consumption, the degradation products of surface-active compounds and TBP. Finally optimized operating conditions have been proposed and a reference test has been performed showing a mineralization out put of about 90% for 167 hours of reaction. Added H{sub 2}O{sub 2} leads to dilute the medium by a factor 2. The main degradation products obtained at the end of reaction are acetic, formic and phosphoric acids. Contrary to acetic and formic acid which will probably be destroyed during following concentration, phosphoric acid behaviour has to be studied in plutonium containing solutions. This study is still in progress. (authors)

  4. Efficient modification of metal oxide surfaces with phosphonic acids by spray coating.

    Science.gov (United States)

    Bulusu, Anuradha; Paniagua, Sergio A; MacLeod, Bradley A; Sigdel, Ajaya K; Berry, Joseph J; Olson, Dana C; Marder, Seth R; Graham, Samuel

    2013-03-26

    We report a rapid method of depositing phosphonic acid molecular groups onto conductive metal oxide surfaces. Solutions of pentafluorobenzyl phosphonic acid (PFBPA) were deposited on indium tin oxide, indium zinc oxide, nickel oxide, and zinc oxide by spray coating substrates heated to temperatures between 25 and 150 °C using a 60 s exposure time. Comparisons of coverage and changes in work function were made to the more conventional dip-coating method utilizing a 1 h exposure time. The data show that the work function shifts and surface coverage by the phosphonic acid were similar to or greater than those obtained by the dip-coating method. When the deposition temperature was increased, the magnitude of the surface coverage and work function shift was also found to increase. The rapid exposure of the spray coating was found to result in less etching of zinc-containing oxides than the dip-coating method. Bulk heterojunction solar cells made of polyhexylthiophene (P3HT) and bis-indene-C60 (ICBA) were tested with PFBPA dip and spray-modified ITO substrates as well as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS)-modified ITO. The spray-modified ITO solar cells showed a similar open circuit voltage (VOC) and fill factor (FF) and a less than 5% lower short circuit current density (JSC) and power conversion efficiency (PCE) than the dip- and PEDOT:PSS-modified ITO. These results demonstrate a potential path to a scalable method to deposit phosphonic acid surface modifiers on metal oxides while overcoming the limitations of other techniques that require long exposure and post-processing times.

  5. Biodegradable polyester films from renewable aleuritic acid: surface modifications induced by melt-polycondensation in air

    Science.gov (United States)

    Jesús Benítez, José; Alejandro Heredia-Guerrero, José; Inmaculada de Vargas-Parody, María; Cruz-Carrillo, Miguel Antonio; Morales-Flórez, Victor; de la Rosa-Fox, Nicolás; Heredia, Antonio

    2016-05-01

    Good water barrier properties and biocompatibility of long-chain biopolyesters like cutin and suberin have inspired the design of synthetic mimetic materials. Most of these biopolymers are made from esterified mid-chain functionalized ω-long chain hydroxyacids. Aleuritic (9,10,16-trihydroxypalmitic) acid is such a polyhydroxylated fatty acid and is also the major constituent of natural lac resin, a relatively abundant and renewable resource. Insoluble and thermostable films have been prepared from aleuritic acid by melt-condensation polymerization in air without catalysts, an easy and attractive procedure for large scale production. Intended to be used as a protective coating, the barrier's performance is expected to be conditioned by physical and chemical modifications induced by oxygen on the air-exposed side. Hence, the chemical composition, texture, mechanical behavior, hydrophobicity, chemical resistance and biodegradation of the film surface have been studied by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), nanoindentation and water contact angle (WCA). It has been demonstrated that the occurrence of side oxidation reactions conditions the surface physical and chemical properties of these polyhydroxyester films. Additionally, the addition of palmitic acid to reduce the presence of hydrophilic free hydroxyl groups was found to have a strong influence on these parameters.

  6. Study on surface acid-base property of carboxylic acid-terminated self-assembled monolayers by cyclic voltammetry and electro-chemical impedance spectroscopy

    Institute of Scientific and Technical Information of China (English)

    罗立强; 程志亮; 杨秀荣; 汪尔康

    2000-01-01

    Cyclic voltammetry and electrochemical impedance spectroscopy were used to study the surface acid-base property of carboxylic acid-terminated self-assembled monolayers (SAMs). A carboxylic acid-terminated thiol, such as thioctic acid (1,2-dithiolane-3-pentanoic acid), was self-assembled on gold electrodes. Electron transfer between the bulk solution and the SAM modified electrode was studied at different pH using Fe(CN)63 as a probe. The surface pK. of thioctic acid was determined by cyclic voltammetry and electrochemical impedance spectroscopy to be 5.6±0.1 and 5.8±0.1, respectively. The method is compared with other methods of monolayer pK.measurement.

  7. Probing the interaction of the amino acid alanine with the surface of ZnO(1010).

    Science.gov (United States)

    Gao, Y K; Traeger, F; Shekhah, O; Idriss, H; Wöll, C

    2009-10-01

    The adsorption modes and stability of the amino acid alanine (NH(2)-CH(CH(3))-COOH) have been studied on the nonpolar single crystal surface of zinc oxide, ZnO(1010), experimentally by X-ray photoelectron spectroscopy (XPS) and computationally using density functional theory (DFT). Deposition at 200 K was found to lead to the formation of multilayers identified by an XPS N1s peak at 401.7 eV assigned to the NH(3)(+) group, a fingerprint of the zwitterionic structure of alanine in the solid state. Heating to 300 K resulted in the removal of most of the multilayers with the remaining surface coverage estimated to 0.4 with respect to Zn cations. At this temperature most of the alanine molecules are found to be deprotonated (dissociated), yielding a carboxylate species (NH(2)-CH(CH(3))-COO(-) (a) + OH (s); where O is surface oxygen, (a) for adsorbed and (s) for surface species). Further heating of the surface resulted in a gradual decrease of the surface coverage and by 500 K a large fraction of adsorbed alanine molecules have desorbed from the surface. Total energy DFT computations of different adsorbate species identified two stable dissociative adsorption modes: bidentate and monodentate. The bidentate species with adsorption energy of 1.75 eV was found to be more stable than the monodentate species by about 0.7 eV.

  8. High yield stress associated with capillary attraction between alumina surfaces in the presence of low molecular weight dicarboxylic acids.

    Science.gov (United States)

    Teh, E-Jen; Leong, Yee-Kwong; Liu, Yinong; Craig, Vincent S J; Walsh, Rick B; Howard, Shaun C

    2010-03-02

    Adsorbed low molecular weight charged molecules are known to give rise to a range of surface forces that affect the rheological behavior of oxide dispersions. The behavior of dicarboxylic acid bolaform compounds in alumina slurry was investigated to determine the influence of the molecular structure on the nanoscale interactions between alumina surfaces and on the macroscopic properties of the slurry. The surface forces in dispersions and between a single particle and a flat surface were characterized by yield stress and atomic force microscopy (AFM) respectively. Absorbed muconic acid increased the yield stress of the alumina system, which indicates an additional attractive interaction between the particles. Adsorbed trans,trans (TT) muconic acid resulted in a much higher yield stress than cis,cis (CC) muconic acid. Force-distance data obtained via AFM displayed features indicating the presence of a capillary force attraction at low pH between the alumina surfaces when TT and CC muconic acids were adsorbed at high surface coverage. This force appeared to explain the high yield stress at low pH (pH 3.6), but the absence of a net attractive force at higher pH (pH 5) did not correlate with the yield stress results. At low pH, the muconic acids become less soluble in the confined space between the interacting surfaces resulting in the formation of an "oily" muconic acid phase located between the interacting surfaces. The nanosized "oil" phase is the source of the capillary force.

  9. A Novel Fiber Optic Surface Plasmon Resonance Biosensors with Special Boronic Acid Derivative to Detect Glycoprotein

    Directory of Open Access Journals (Sweden)

    Yang Zhang

    2017-10-01

    Full Text Available We proposed and demonstrated a novel tilted fiber Bragg grating (TFBG-based surface plasmon resonance (SPR label-free biosensor via a special boronic acid derivative to detect glycoprotein with high sensitivity and selectivity. TFBG, as an effective sensing element for optical sensing in near-infrared wavelengths, possess the unique capability of easily exciting the SPR effect on fiber surface which coated with a nano-scale metal layer. SPR properties can be accurately detected by measuring the variation of transmitted spectra at optical communication wavelengths. In our experiment, a 10° TFBG coated with a 50 nm gold film was manufactured to stimulate SPR on a sensor surface. To detect glycoprotein selectively, the sensor was immobilized using designed phenylboronic acid as the recognition molecule, which can covalently bond with 1,2- or 1,3-diols to form five- or six-membered cyclic complexes for attaching diol-containing biomolecules and proteins. The phenylboronic acid was synthetized with long alkyl groups offering more flexible space, which was able to improve the capability of binding glycoprotein. The proposed TFBG-SPR sensors exhibit good selectivity and repeatability with a protein concentration sensitivity up to 2.867 dB/ (mg/mL and a limit of detection (LOD of 15.56 nM.

  10. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Energy Technology Data Exchange (ETDEWEB)

    Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India); Methattel Raman, Shijeesh [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India)

    2016-04-18

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  11. Biological and surface-active properties of double-chain cationic amino acid-based surfactants.

    Science.gov (United States)

    Greber, Katarzyna E; Dawgul, Małgorzata; Kamysz, Wojciech; Sawicki, Wiesław; Łukasiak, Jerzy

    2014-08-01

    Cationic amino acid-based surfactants were synthesized via solid phase peptide synthesis and terminal acylation of their α and ε positions with saturated fatty acids. Five new lipopeptides, N-α-acyl-N-ε-acyl lysine analogues, were obtained. Minimum inhibitory concentration and minimum bactericidal (fungicidal) concentration were determined on reference strains of bacteria and fungi to evaluate the antimicrobial activity of the lipopeptides. Toxicity to eukaryotic cells was examined via determination of the haemolytic activities. The surface-active properties of these compounds were evaluated by measuring the surface tension and formation of micelles as a function of concentration in aqueous solution. The cationic surfactants demonstrated diverse antibacterial activities dependent on the length of the fatty acid chain. Gram-negative bacteria and fungi showed a higher resistance than Gram-positive bacterial strains. It was found that the haemolytic activities were also chain length-dependent values. The surface-active properties showed a linear correlation between the alkyl chain length and the critical micelle concentration.

  12. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Science.gov (United States)

    Puthirath, Anand B.; Methattel Raman, Shijeesh; Varma, Sreekanth J.; Jayalekshmi, S.

    2016-04-01

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  13. Optimization of acrylic acid grafting onto polypropylene using response surface methodology and its biodegradability

    Science.gov (United States)

    Mandal, Dev K.; Bhunia, Haripada; Bajpai, Pramod K.; Kushwaha, Jai P.; Chaudhari, Chandrasekhar V.; Dubey, Kumar A.; Varshney, Lalit

    2017-03-01

    Simultaneous radiation grafting was optimized to graft acrylic acid monomer on the polypropylene (PP) films to make them hydrophilic and enhance their biodegradability. Experiments were designed based on full factorial central composite design (response surface methodology) and influence of monomer concentration, radiation dose, inhibitor concentration, solvent concentration on degree of grafting was investigated. The extent of grafting was found to increase with increasing monomer concentration, inhibitor concentration and radiation dose. The targeted 35% grafting could be achieved at optimum condition viz. monomer concentration 12.09 wt%, radiation dose 12.40 kGy, inhibitor concentration 0.07 M and solvent concentration 0.12 M. The grafted PP films at different degrees of grafting were tested for tensile properties and characterized by swelling studies, fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Successful grafting of acrylic acid onto polypropylene films was indicated by FTIR and confirmed quantitatively by determination of carboxylic groups on the film surface. Tensile strength of grafted PP films decreased with increase in degree of grafting. The crystallinity of the grafted PP films was lower than that of PP film as indicated by DSC studies. Grafting of acrylic acid increased the roughness on the surface of PP films indicated by SEM studies. The maximum biodegradability of the 34.55% grafted film was 5.5%.

  14. Effects of acid treatment on the clay palygorskite: XRD, surface area, morphological and chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Xavier, Katiane Cruz Magalhaes; Santos, Maria do Socorro Ferreira dos; Santos, Maria Rita Morais Chaves; Oliveira, Marilia Evelyn Rodrigues; Osajima, Josy Antevelli; Silva Filho, Edson Cavalcanti da [Universidade Federal do Piaui (UFPI), Teresina, PI (Brazil); Carvalho, Maria Wilma Nunes Cordeiro, E-mail: edsonfilho@ufpi.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2014-08-15

    The palygorskite is an aluminum-magnesium silicate that has a fibrous morphology. Their physicochemical characteristics are the result of high surface area, porosity and thermal resistance which make it an attractive adsorbent. Its adsorption capacity can be increased through chemical reactions and/or heat treatments. The objective of this work is to verify the effects of acid activation on the palygorskite, treated with HCl at 90 °C at concentrations of 2, 4 and 6 mol L{sup -1} in 2 and 4 hours, with clay/acid solution ratio 1 g 10 mL{sup -1} and characterized by techniques: XRF, XRD and surface area. A significant increase in specific surface area was observed in the sample treated with HCl at the concentration 6 mol L{sup -1}. The changes were more pronounced at stricter concentrations of acidity, with decreasing intensity of reflection of the clay indicated in the XRD. These changes were confirmed in the XRF with the leaching of some oxides and with increasing concentration of SiO{sub 2}. (author)

  15. Protein adsorption on the poly(L-lactic acid) surface modified by chitosan and its derivatives

    Institute of Scientific and Technical Information of China (English)

    JIAO YanPeng; ZHOU ChangRen; LI LiHua; DING Shan; LU Lu; LUO BingHong; LI Hong

    2009-01-01

    Surface modification of biomaterials has been adopted over the years to improve their biocompatibility.In this study,aiming to promote hydrophilicity and to introduce natural recognition sites onto poly(L-lactic acid) (PLLA) films,chitosan and its derivatives,carboxymethyl chitosan(CMC) and N-methylene phosphonic chitosan (NPC),were used to modify the surface of PLLA films by an entrapment method. Radiolabeled (12SI) proteins were used to measure the amount of protein adsorbed to PLLA surfaces. Fibronectin (Fn) was used to study the protein adsorption on the modified PLLA surfaces,including isotherm adsorption and adsorption kinetics of single protein,competitive adsorption of binary proteins system and serum multi-proteins and the desorption behavior in serum solution. The results showed that in the isotherm adsorption,Fn had a larger adsorption capacity on the CS-modified surface at lower concentrations,but had a high adsorption capacity at CMC-modified surface at higher concentrations. In the study of absorption kinetics,Fn had a fastest adsorption equilibrium and a highest equilibrium adsorption capacity at the CS-modified surface,while it was opposite at the PCS-modified surface. When BSA and serum were added,it had the greatest effect on the adsorption of Fn on the PCS-modified surface. After 6 hours soaking in the desorption study,Fn had reached desorption equilibrium on all the modified surfaces,which had different effects on the desorption rate and the remaining percentage of Fn.

  16. Preparation and surface active properties of a-acyloxysuccinic acid derivatives from malic acid and fatty acids of crude rice bran oil

    Directory of Open Access Journals (Sweden)

    El-Sawy, A. A.

    2000-10-01

    Full Text Available Surface active compounds were prepared from malic acid by esterification with acyl chloride (IIa-d, of [palmitic, stearic, oleic, linoleic and mixed fatty acids of rice bran oil (RBO (IIe], in the presence of pyridine as catalyst, forming (IIIa-e ,  which are  converted to anionic disodium salt (IVa-e . The prepared a-acyl-oxysuccinic acid derivatives (IIIa-e was oxypropenoxylated with various moles of propylene oxide (n= 2, 4, 6 and 8 to give (V-IXa-d . These compounds were converted to nonionic surfactants with two terminal amide oxime groups  (XV-XIXa-d as molecular aggregations and surface active agents in aqueous media. The structures were confirmed by micro analysis, IR and 1H NMR spectra. The surface active properties of the prepared compounds revealed excellent results.Se han preparado compuestos de tensión superficial a partir de ácido málico por esterificación con cloruro de acilo (IIa-d de [palmítico, esteárico, oleico, linoleico y ácidos grasos mezclados de aceite de gérmen de arroz (RBO (IIe], en presencia de piridina como catalizador, formando (IIIa-e, los cuales son convertidos a sales disódicas aniónicas (IVa-e. El derivado del ácido a-acil-oxisuccínico preparado (IIIa-e fue oxipropenoxilado con varios moles de óxido de propileno (n=2, 4, 6 y 8 para dar (V-IXa-d. Estos compuestos fueron convertidos en tensioactivos no iónicos con dos grupos amida oxima terminal (XV-XIXa-d como agregaciones moleculares y agentes tensioactivos en medio acuoso. Las estructuras se confirmaron por microanálisis, IR y espectros de 1H NMR. Las propiedades tensioactivas de los compuestos preparados revelaron excelentes resultados.

  17. Revegetation of Acid Rock Drainage (ARD) Producing Slope Surface Using Phosphate Microencapsulation and Artificial Soil

    Science.gov (United States)

    Kim, Jae Gon

    2017-04-01

    Oxidation of sulfides produces acid rock drainage (ARD) upon their exposure to oxidation environment by construction and mining activities. The ARD causes the acidification and metal contamination of soil, surface water and groundwater, the damage of plant, the deterioration of landscape and the reduction of slope stability. The revegetation of slope surface is one of commonly adopted strategies to reduce erosion and to increase slope stability. However, the revegetation of the ARD producing slope surface is frequently failed due to its high acidity and toxic metal content. We developed a revegetation method consisting of microencapsualtion and artificial soil in the laboratory. The revegetation method was applied on the ARD producing slope on which the revegetation using soil coverage and seeding was failed and monitored the plant growth for one year. The phosphate solution was applied on sulfide containing rock to form stable Fe-phosphate mineral on the surface of sulfide, which worked as a physical barrier to prevent contacting oxidants such as oxygen and Fe3+ ion to the sulfide surface. After the microencapsulation, two artificial soil layers were constructed. The first layer containing organic matter, dolomite powder and soil was constructed at 2 cm thickness to neutralize the rising acidic capillary water from the subsurface and to remove the dissolved oxygen from the percolating rain water. Finally, the second layer containing seeds, organic matter, nutrients and soil was constructed at 3 cm thickness on the top. After application of the method, the pH of the soil below the artificial soil layer increased and the ARD production from the rock fragments reduced. The plant growth showed an ordinary state while the plant died two month after germination for the previous revegetation trial. No soil erosion occurred from the slope during the one year field test.

  18. Comparison of alkaline phosphatase activity of MC3T3-E1 cells cultured on different Ti surfaces: modified sandblasted with large grit and acid-etched (MSLA), laser-treated, and laser and acid-treated Ti surfaces

    Science.gov (United States)

    Li, Lin-Jie; Kim, So-Nam

    2016-01-01

    PURPOSE In this study, the aim of this study was to evaluate the effect of implant surface treatment on cell differentiation of osteoblast cells. For this purpose, three surfaces were compared: (1) a modified SLA (MSLA: sand-blasted with large grit, acid-etched, and immersed in 0.9% NaCl), (2) a laser treatment (LT: laser treatment) titanium surface and (3) a laser and acid-treated (LAT: laser treatment, acid-etched) titanium surface. MATERIALS AND METHODS The MSLA surfaces were considered as the control group, and LT and LAT surfaces as test groups. Alkaline phosphatase expression (ALP) was used to quantify osteoblastic differentiation of MC3T3-E1 cell. Surface roughness was evaluated by a contact profilometer (URFPAK-SV; Mitutoyo, Kawasaki, Japan) and characterized by two parameters: mean roughness (Ra) and maximum peak-to-valley height (Rt). RESULTS Scanning electron microscope revealed that MSLA (control group) surface was not as rough as LT, LAT surface (test groups). Alkaline phosphatase expression, the measure of osteoblastic differentiation, and total ALP expression by surface-adherent cells were found to be highest at 21 days for all three surfaces tested (P.05). CONCLUSION This study suggested that MSLA and LAT surfaces exhibited more favorable environment for osteoblast differentiation when compared with LT surface, the results that are important for implant surface modification studies. PMID:27350860

  19. Optimization of succinic acid fermentation with Actinobacillus succinogenes by response surface methodology (RSM)

    Institute of Scientific and Technical Information of China (English)

    Yun-jian ZHANG; Qiang LI; Yu-xiu ZHANG; Dan WANG; Jian-min XING

    2012-01-01

    Succinic acid is considered as an important platform chemical.Succinic acid fermentation with Actinobacillus succinogenes strain BE-1 was optimized by central composite design (CCD) using a response surface methodology (RSM).The optimized production of succinic acid was predicted and the interactive effects between glucose,yeast extract,and magnesium carbonate were investigated.As a result,a model for predicting the concentration of succinic acid production was developed.The accuracy of the model was confirmed by the analysis of variance (ANOVA),and the validity was further proved by verification experiments showing that percentage errors between actual and predicted values varied from 3.02% to 6.38%.In addition,it was observed that the interactive effect between yeast extract and magnesium carbonate was statistically significant.In conclusion,RSM is an effective and useful method for optimizing the medium components and investigating the interactive effects,and can provide valuable information for succinic acid scale-up fermentation using A.succinogenes strain BE-1.

  20. Surface and interlayer base-characters in lepidocrocite titanate: The adsorption and intercalation of fatty acid

    Energy Technology Data Exchange (ETDEWEB)

    Maluangnont, Tosapol, E-mail: tosapol.ma@kmitl.ac.th [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Catalytic Chemistry Research Unit, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Arsa, Pornanan [Catalytic Chemistry Research Unit, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Department of Chemistry, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Limsakul, Kanokporn; Juntarachairot, Songsit; Sangsan, Saithong [Department of Chemistry, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Gotoh, Kazuma [Graduate School of Natural Science & Technology, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530 (Japan); Sooknoi, Tawan, E-mail: kstawan@gmail.com [Catalytic Chemistry Research Unit, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Department of Chemistry, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

    2016-06-15

    While layered double hydroxides (LDHs) with positively-charged sheets are well known as basic materials, layered metal oxides having negatively-charged sheets are not generally recognized so. In this article, the surface and interlayer base-characters of O{sup 2−} sites in layered metal oxides have been demonstrated, taking lepidocrocite titanate K{sub 0.8}Zn{sub 0.4}Ti{sub 1.6}O{sub 4} as an example. The low basicity (0.04 mmol CO{sub 2}/g) and low desorption temperature (50–300 °C) shown by CO{sub 2}− TPD suggests that O{sup 2−} sites at the external surfaces is weakly basic, while those at the interlayer space are mostly inaccessible to CO{sub 2}. The liquid-phase adsorption study, however, revealed the uptake as much as 37% by mass of the bulky palmitic acid (C{sub 16} acid). The accompanying expansion of the interlayer space by ~0.1 nm was detected by PXRD and TEM. In an opposite manner to the external surfaces, the interlayer O{sup 2−} sites can deprotonate palmitic acid, forming the salt (i.e., potassium palmitate) occluded between the sheets. Two types of basic sites are proposed based on ultrafast {sup 1}H MAS NMR and FTIR results. The interlayer basic sites in lepidocrocite titanate leads to an application of this material as a selective and stable two-dimensional (2D) basic catalyst, as demonstrated by the ketonization of palmitic acid into palmitone (C{sub 31} ketone). Tuning of the catalytic activity by varying the type of metal (Zn, Mg, and Li) substituting at Ti{sup IV} sites was also illustrated. - Graphical abstract: Interlayer basic sites in lepidocrocite titanate, K{sub 0.8}Zn{sub 0.4}Ti{sub 1.6}O{sub 4}, lead to an intercalation of palmitic acid with a layer expansion. Display Omitted - Highlights: • K{sub 0.8}Zn{sub 0.4}Ti{sub 1.6}O{sub 4} intercalates palmitic acid, forming the occluded potassium salt. • The interlayer expansion is evidenced by PXRD patterns and TEM image. • Two types of basic sites are deduced from ultrafast

  1. Accessible reactive surface area and abiotic redox reactivity of iron oxyhydroxides in acidic brines

    Science.gov (United States)

    Strehlau, Jennifer H.; Toner, Brandy M.; Arnold, William A.; Penn, R. Lee

    2017-01-01

    The reactivity of iron oxyhydroxide nanoparticles in low pH and high ionic strength solutions was quantified to assess abiotic contributions to oxidation-reduction chemistry in acidic brine environments, such as mine groundwater seepage, lakes in Western Australia, and acid mine drainage settings, which are of global interest for their environmental impacts and unique geomicrobiology. Factors expected to influence accessible and reactive surface area, including Fe(II) adsorption and aggregate size, were measured as a function of pH and CaCl2 concentration and related to the kinetics of redox reactions in aqueous suspensions of synthetic goethite (α-FeOOH), akaganeite (β-FeOOH), and ferrihydrite (Fe10O14(OH)2) nanoparticles. Aqueous conditions and iron oxyhydroxides were chosen based on characterization of natural iron-rich mine microbial mats located in Soudan Underground Mine State Park, Minnesota, USA. Quinone species were used as redox sensors because they are well-defined probes and are present in natural organic matter. Fe(II) adsorption to the iron oxyhydroxide mineral surfaces from aqueous solution was measurable only at pH values above 4 and either decreased or was not affected by CaCl2 concentration. Concentrations at or above 0.020 M CaCl2 in acetate buffer (pH 4.5) induced particle aggregation. Assessment of Fe(II) adsorption and particle aggregation in acidic brine suggested that accessible reactive surface area may be limited in acidic brines. This was supported by observations of decreasing benzoquinone reduction rate by adsorbed Fe(II) at high CaCl2 concentration. In contrast, the hydroquinone oxidation rate increased at high CaCl2 concentrations, which may be due to suppressed adsorption of Fe(II) generated by the reaction. Results suggest that iron geochemical cycling in acidic brine environments will be substantially different than for iron oxyhydroxides in low-saline waters with circumneutral pH. These findings have implications for acidic

  2. Surface plasmon resonance analysis of antibiotics using imprinted boronic acid-functionalized Au nanoparticle composites.

    Science.gov (United States)

    Frasconi, Marco; Tel-Vered, Ran; Riskin, Michael; Willner, Itamar

    2010-03-15

    Au nanoparticles (NPs) are functionalized with thioaniline electropolymerizable groups and (mercaptophenyl)boronic acid. The antibiotic substrates neomycin (NE), kanamycin (KA), and streptomycin (ST) include vicinal diol functionalities and, thus, bind to the boronic acid ligands. The electropolymerization of the functionalized Au NPs in the presence of NE, KA, or ST onto Au surfaces yields bisaniline-cross-linked Au NP composites that, after removal of the ligated antibiotics, provide molecularly imprinted matrixes which reveal high sensitivities toward the sensing of the imprinted antibiotic analytes (detection limits for analyzing NE, KA, and ST correspond to 2.00 +/- 0.21 pM, 1.00 +/- 0.10 pM, and 200 +/- 30 fM, respectively). The antibiotics are sensed by surface plasmon resonance (SPR) spectroscopy, where the coupling between the localized plasmon of the NPs and the surface plasmon wave associated with the Au surface is implemented to amplify the SPR responses. The imprinted Au NP composites are, then, used to analyze the antibiotics in milk samples.

  3. Surface roughness of flowable resin composites eroded by acidic and alcoholic drinks

    Directory of Open Access Journals (Sweden)

    Claudio Poggio

    2012-01-01

    Full Text Available Aim: The aim of this study is to evaluate the surface roughness of four flowable resin composites following exposure to acidic and alcoholic drinks. Materials and Methods: SureFil SDR flow, TetricEvoFlow, Esthet-X Flow and Amaris Flow HT samples were immersed in artificial saliva, Coca Cola and Chivas Regal Whisky. Each specimen was examined using a Leica DCM 3D microscope: Arithmetical mean height of the surface profiles was measured (Sa. Results: Kruskal-Wallis test showed significant differences among various groups (P<0,001. Mann Whitney test was applied and control groups showed significantly lower Sa values than other groups (P=0,008. Coca Cola groups showed highest Sa values (P<0,021. No significant differences (P=0,14 in surface texture were found among the specimens of the different materials. No significant differences were found among TetricEvoFlow, Esthet-X Flow and Amaris Flow under control conditions nor after Coca Cola application. Under control condition and after Coca Cola application SureFil SDR flow showed significantly higher Sa values. Moreover, after whisky application Amaris Flow showed significantly lower Sa values then the other three groups that showed no significant differences among them. Conclusions: Acidic and alcoholic drinks eroded the surface roughness of all evaluated flowable resin composites.

  4. Stereochemistry and thermal stability of tartaric acid on the intrinsically chiral Cu{531} surface

    Science.gov (United States)

    Baldanza, Silvia; Ardini, Jacopo; Giglia, Angelo; Held, Georg

    2016-01-01

    Intrinsically chiral metal surfaces provide enantiospecific reaction environments without the need of co-adsorbed modifiers. Amongst the intrinsically chiral copper surfaces, Cu{531} has the smallest unit cell and the highest density of chiral sites. XPS, NEXAFS and TPD were employed to investigate the adsorption and decomposition behaviour of the two chiral enantiomers of tartaric acid on this surface. The results obtained from XPS and NEXAFS show that at saturation coverage both enantiomers of tartaric acid adsorb in a μ4 configuration through the two carboxylic groups, which are rotated with respect to each other by 90° ± ≈ 15° within the surface plane. At intermediate coverage the R,R enantiomer adopts a similar configuration, but the S,S enantiomer is different and shows a high degree of dissociation. Growth of multilayers is observed at high exposures when the sample is kept at below 370 K. TPD experiments show that multilayers desorb between 390 K and 470 K and decomposition of the chemisorbed layer occurs between 470 K and 600 K. The desorption spectra support a two-step decomposition mechanism with a Odbnd Cdbnd Cdbnd O or HO-HCdbnd CH-OH intermediate that leads to production of CO2 and CO. Enantiomeric differences are observed in the desorption features related to the decomposition of the chemisorbed layer.

  5. Modification of the cellulosic component of hemp fibers using sulfonic acid derivatives: Surface and thermal characterization.

    Science.gov (United States)

    George, Michael; Mussone, Paolo G; Bressler, David C

    2015-12-10

    The aim of this study was to characterize the surface, morphological, and thermal properties of hemp fibers treated with two commercially available, inexpensive, and water soluble sulfonic acid derivatives. Specifically, the cellulosic component of the fibers were targeted, because cellulose is not easily removed during chemical treatment. These acids have the potential to selectively transform the surfaces of natural fibers for composite applications. The proposed method proceeds in the absence of conventional organic solvents and high reaction temperatures. Surface chemical composition and signature were measured using gravimetric analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR). XPS data from the treated hemp fibers were characterized by measuring the reduction in O/C ratio and an increase in abundance of the C-C-O signature. FTIR confirmed the reaction with the emergence of peaks characteristic of disubstituted benzene and amino groups. Grafting of the sulfonic derivatives resulted in lower surface polarity. Thermogravimetric analysis revealed that treated fibers were characterized by lower percent degradation between 200 and 300 °C, and a higher initial degradation temperature.

  6. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    Science.gov (United States)

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA.

  7. Sb Surface Modification of Pd by Mimetic Underpotential Deposition for Formic Acid Oxidation

    Directory of Open Access Journals (Sweden)

    Long-Long Wang

    2015-07-01

    Full Text Available The newly proposed mimetic underpotential deposition (MUPD technique was extended to modify Pd surfaces with Sb through immersing a Pd film electrode or dispersing Pd/C powder in a Sb(III-containing solution blended with ascorbic acid (AA. The introduction of AA shifts down the open circuit potential of Pd substrate available to achieve suitable Sb modification. The electrocatalytic activity and long-term stability towards HCOOH electrooxidation of the Sb modified Pd surfaces (film electrode or powder catalyst by MUPD is superior than that of unmodified Pd and Sb modified Pd surfaces by conventional UPD method. The enhancement of electrocatalytic performance is due to the third body effect and electronic effect, as well as bi-functional mechanism induced by Sb modification which result in increased resistance against CO poisoning.

  8. Phytic acid adsorption on the copper surface: Observation of electrochemistry and Raman spectroscopy

    Science.gov (United States)

    Shen, Shu; Guo, Xiao-yu; Song, Ping; Pan, Ying-Cheng; Wang, Hao-qiong; Wen, Ying; Yang, Hai-Feng

    2013-07-01

    The adsorption of phytic acid (PA) on copper was investigated using electrochemical impedance spectroscopy (EIS), electrochemical polarization measurement and surface-enhanced Raman scattering (SERS) spectroscopy. Electrochemical results indicated that inhibition efficiency of PA film for copper from corrosion in 3 wt% NaCl solution was beyond 80% at an optimum self-assembly concentration of 0.1 mM for 6 h. Electrochemical polarization indicated that PA functioned as a cathodic inhibitor. In addition, Raman studies showed that PA adsorbed on the copper surface formed via P-O groups. Finally, the value of ΔGads (-39.96 kJ mol-1) was close to -40 kJ mol-1, suggesting that the adsorption of PA on the copper surface was the chemical adsorption.

  9. Theoretical investigation of the atomic and electronic structure of amino acids on Si(100) surfaces

    Science.gov (United States)

    Luo, Xuan; Qian, Gefei; Sagui, Celeste; Roland, Christopher

    2006-03-01

    There are currently considerable efforts underway to combine silicon-based device technology with myriad of organic molecules, thereby fabricating new structures that take advantage of the tunable electronic and optical properties of organic molecules. A key aspect of this integration process is binding of the organics to the silicon surfaces. As part of this effort, we have been investigating the binding of several amino acids -- the building blocks for proteins -- on the Si (100) surface with state-of-the art density functional theory methods. Specifically, the binding between the buckled Si(100) and the NH2, CH2, COOH, C=0 and NC entities at various surface sites have been investigated. We report and discuss on the resulting structures and their electronic properties.

  10. Ternary solution of sodium chloride, succinic acid and water; surface tension and its influence on cloud droplet activation

    Directory of Open Access Journals (Sweden)

    J. Vanhanen

    2008-08-01

    Full Text Available Surface tension of ternary solution of sodium chloride, succinic acid and water was measured as a function of both composition and temperature by using the capillary rise technique. Both sodium chloride and succinic acid are found in atmospheric aerosols, the former being main constituent of marine aerosol. Succinic acid was found to decrease the surface tension of water already at very low concentrations. Sodium chloride increased the surface tension linearly as a function of the concentration. Surface tensions of both binary solutions agreed well with the previous measurements. Succinic acid was found to lower the surface tension even if sodium chloride is present, indicating that succinic acid, as a surface active compound, tends to concentrate to the surface. An equation based on thermodynamical relations was fitted to the data and extrapolated to the whole concentration range by using estimated surface tensions for pure compounds. As a result, we obtained an estimate of surface tensions beyond solubility limits in addition to a fit to the experimental data. The parameterization can safely be used at temperatures from 10 to 30°C. These kinds of parameterizations are important for example in atmospheric nucleation models. To investigate the influence of surface tension on cloud droplet activation, the surface tension parameterization was included in an adiabatic air parcel model. Usually in cloud models the surface tension of pure water is used. Simulations were done for characteristic marine aerosol size distributions consisting of the considered ternary mixture. We found that by using the surface tension of pure water, the amount of activated particles is underestimated up to 8% if particles contain succinic acid and overestimated it up to 8% if particles contain only sodium chloride. The surface tension effect was found to increase with increasing updraft velocity.

  11. Acid base surface properties of glass-ionomers determined by IGC

    Science.gov (United States)

    Voelkel, A.; Andrzejewska, E.; Limanowska-Shaw, H.; Andrzejewski, M.

    2005-05-01

    SummaryThe surface properties of several glass-ionomer restorative dental materials (GC Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated by means of inverse gas chromatography. The capacity of the surface of glass-ionomers to undergo specific interactions was expressed using the specific component of free energy Δ Gs as well as the parameters KA and KD to describe the ability of the cement to act both as an electron acceptor and an electron donor, respectively. The character of the examined surface was expressed with the use of the SC parameter. All these parameters were determined with a high degree of precision. It was found that the surface of glass-ionomer cements had a well-marked acidic character. The ability of the cement surface to take part in specific interactions differed with the various types of commercial products. The surface activity of the glass-ionomers investigated changed with the storage time (up to 6 months) indicating an on-going setting reaction.

  12. Folic acid functionalized surface highlights 5-methylcytosine-genomic content within circulating tumor cells

    KAUST Repository

    Malara, Natalia

    2014-07-01

    Although the detection of methylated cell free DNA represents one of the most promising approaches for relapse risk assessment in cancer patients, the low concentration of cell-free circulating DNA constitutes the biggest obstacle in the development of DNA methylation-based biomarkers from blood. This paper describes a method for the measurement of genomic methylation content directly on circulating tumor cells (CTC), which could be used to deceive the aforementioned problem. Since CTC are disease related blood-based biomarkers, they result essential to monitor tumor\\'s stadiation, therapy, and early relapsing lesions. Within surface\\'s bio-functionalization and cell\\'s isolation procedure standardization, the presented approach reveals a singular ability to detect high 5-methylcytosine CTC-subset content in the whole CTC compound, by choosing folic acid (FA) as transducer molecule. Sensitivity and specificity, calculated for FA functionalized surface (FA-surface), result respectively on about 83% and 60%. FA-surface, allowing the detection and characterization of early metastatic dissemination, provides a unique advance in the comprehension of tumors progression and dissemination confirming the presence of CTC and its association with high risk of relapse. This functionalized surface identifying and quantifying high 5-methylcytosine CTC-subset content into the patient\\'s blood lead significant progress in cancer risk assessment, also providing a novel therapeutic strategy.© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Computational study of cis-oleic acid adsorption on Ni(1 1 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica, IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, Facultad Regional Bahia Blanca, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Ulacco, S. [Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, Facultad Regional Bahia Blanca, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Brizuela, G.; Juan, A. [Departamento de Fisica, IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

    2012-05-15

    In the present work, the Atom Superposition and Electron Delocalization method has been applied in order to study the adsorption of cis-oleic acid on Ni(1 1 1) surface. This molecule presents two active functional groups, C=C (in the middle) and -COOH (at one end). Therefore, it is important to explore adsorption on the metal surface through the C=C bond in a geometry parallel to the surface and also in a vertical one with -COOH pointing at Ni atoms. Our results indicate that the parallel geometry is more stable than the vertical one and C=C bond adsorption dominates the process. Energetic results show a strong interaction with the metallic surface. Ni-Ni, C=C, and C-C bonds are weakened upon adsorption because of a bonding interaction between carbons and nickel surface. We found that Ni 5d{sub z}{sup 2} and 5d{sub yz} orbitals play an important role in the bonding between C p{sub x}, p{sub z} orbitals and surface, and the same happens with Ni 6p{sub x} and Ni 6p{sub z}. A small Ni-H interaction is also detected.

  14. Surface and interlayer base-characters in lepidocrocite titanate: The adsorption and intercalation of fatty acid

    Science.gov (United States)

    Maluangnont, Tosapol; Arsa, Pornanan; Limsakul, Kanokporn; Juntarachairot, Songsit; Sangsan, Saithong; Gotoh, Kazuma; Sooknoi, Tawan

    2016-06-01

    While layered double hydroxides (LDHs) with positively-charged sheets are well known as basic materials, layered metal oxides having negatively-charged sheets are not generally recognized so. In this article, the surface and interlayer base-characters of O2- sites in layered metal oxides have been demonstrated, taking lepidocrocite titanate K0.8Zn0.4Ti1.6O4 as an example. The low basicity (0.04 mmol CO2/g) and low desorption temperature (50-300 °C) shown by CO2- TPD suggests that O2- sites at the external surfaces is weakly basic, while those at the interlayer space are mostly inaccessible to CO2. The liquid-phase adsorption study, however, revealed the uptake as much as 37% by mass of the bulky palmitic acid (C16 acid). The accompanying expansion of the interlayer space by ~0.1 nm was detected by PXRD and TEM. In an opposite manner to the external surfaces, the interlayer O2- sites can deprotonate palmitic acid, forming the salt (i.e., potassium palmitate) occluded between the sheets. Two types of basic sites are proposed based on ultrafast 1H MAS NMR and FTIR results. The interlayer basic sites in lepidocrocite titanate leads to an application of this material as a selective and stable two-dimensional (2D) basic catalyst, as demonstrated by the ketonization of palmitic acid into palmitone (C31 ketone). Tuning of the catalytic activity by varying the type of metal (Zn, Mg, and Li) substituting at TiIV sites was also illustrated.

  15. Characterization of an organic acid analog model in Adirondack, New York, surface waters

    Science.gov (United States)

    Fakhraei, H.; Driscoll, C. T.

    2013-12-01

    Natural waters include a variety of organic matter that differs in composition and functional groups. Dissolved organic matter is important but difficult to characterize acidic and metal binding (e.g., Al) functional groups in chemical equilibrium models. In this study data from Adirondack Lake Survey were used to calibrate an organic acid analog model in order to quantify the influence of organic acids on surface water chemistry. The study sites in the Adirondack region of New York have diverse levels of dissolved organic carbon (DOC), used as a surrogate for organic acids. DOC in 55 Adirondack surface waters varies from 180 μmol C/l (in Little Echo Pond) to 1263 μmol C/l (in Sunday Pond). To reduce the variability inherited in the large raw data set, suite of mean observations was constructed by grouping and averaging measured data into pH intervals of 0.05 pH units from pH 4.15 to 7.3. A chemical equilibrium model, which includes major solutes in natural waters, was linked to an optimization algorithm (genetic algorithm) to calibrate a triprotic organic analog model which includes proton and aluminum binding by adjusting the dissociation constants and site density of DOC. The object of fitting procedure was to simultaneously minimize the discrepancy between observed and simulated pH, acid neutralizing capacity (ANC), organic monomeric aluminum and inorganic monomeric aluminum. A sensitivity analysis on calibrated values indicate that the speciation of the modeled solutes are most responsive to the dissociation constant of AlOrg= Al3+ + Org3- reaction (Org3- represents organic anion), the site density of DOC and the second H+ dissociation constant of the triprotic organic analog (i.e. H2Org- = 2H+ + Org3- reaction).

  16. Validation of peracetic acid as a sporicide for sterilization of working surfaces in biological safety cabinets

    Directory of Open Access Journals (Sweden)

    Sandra Regina B.R. Sella

    2012-09-01

    Full Text Available Objectives: This study aimed to validate the use of peracetic acid as sporicide agent to decontaminate the workingsurface of a laminar flow biological safety cabinet (BSC, as an alternative to glutaraldehyde, including the selection ofthe disinfecting agent, the method of application, and the contact time.Materials and methods: The test organism was the spore-forming bacterium Bacillus atrophaeus ATCC 9372, which isa surrogate for an important infectious agent. Spore cultures were prepared from B. atrophaeus and used them to testthe sporicidal efficacy of peracetic acid on a BSC stainless steel surface. The performance of the sterilant was assessedby determining minimal inhibitory concentration (MIC and by microbial challenge in conditions that mimicked surfacecontamination. It was used 2.0% glutaraldehyde solution as the control.Results: The range of MICs was 0.6-1.1% for the control and 0.003-0.006% for the 0.2% peracetic acid solution. The 0.2%peracetic acid was an effective sterilant against B. atrophaeus spores (6-7 log spores, under defined conditions of useafter 40 min contact time, which was double that recommended on the product label.Conclusion: It was conclude that while the results of official methods can help to evaluate how products will perform,they are not usually reproducible in real-life user conditions and environments. Validation tests must be carried out toensure the efficacy and safety of surface decontamination procedures. J Microbiol Infect Dis 2012; 2(3: 93-99Key words: Peracetic acid, sporicidal activity, sterility, Bacillus atrophaeus spores, glutaraldehyde

  17. Acid Aging Effects on Surfaces of PTFE Gaskets Investigated by Fourier Transform Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Giorgini

    2016-09-01

    Full Text Available This paper investigates the effect of a prolonged acid and thermal attack, on the surface of PTFE by Fourier Transform Infrared Micro-Spectroscopy (FT-IR. The materials are commercialized by two alternative producers in form of Teflon tapes. These tapes are installed in process plants where tires moulds are cleaned inside a multistage ultrasonic process. In these cases, Teflon tapes, having a role of gaskets, show inexplicably phenomena of degradation in relatively short operation periods. Even considering that these gaskets are exposed to the combined effect of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the possibility of these severe erosion phenomena. An interesting explanation can be related to the potential presence in the cleaning solution, mainly based on sulfamic acid, of highly reactive chemical compounds, as chlorides and fluorides, originated by the disaggregation of elements from the tire composition and/or additives used as processing aids and/or by catalytic effect generated by fluorine produced by PTFE degradation. In general, up to 300 different chemical elements, both organic and inorganic, natural and synthetic, are merged in a tire. Since this composition is practically unknown, especially regarding additives and “unusual elements”, representing a secrecy of each tire manufactures, it is really complex to define the chemical composition of the cleaning solution with an appropriate precision. As a consequence, the gaskets have been treated with different mixtures of acids in the way to combine a larger range of possibilities. Thus, the FT-IR experimental characterization of PTFE surface properties followed an appropriate accelerated aging, aiming at actuating the specific mechanics of wearing as in industrial use. The different acid treatments adopted for accelerating the aging of gaskets have highlighted the different behaviour of the PTFE matrix, but

  18. Lactic acid bacteria in dairy food: surface characterization and interactions with food matrix components.

    Science.gov (United States)

    Burgain, J; Scher, J; Francius, G; Borges, F; Corgneau, M; Revol-Junelles, A M; Cailliez-Grimal, C; Gaiani, C

    2014-11-01

    This review gives an overview of the importance of interactions occurring in dairy matrices between Lactic Acid Bacteria and milk components. Dairy products are important sources of biological active compounds of particular relevance to human health. These compounds include immunoglobulins, whey proteins and peptides, polar lipids, and lactic acid bacteria including probiotics. A better understanding of interactions between bioactive components and their delivery matrix may successfully improve their transport to their target site of action. Pioneering research on probiotic lactic acid bacteria has mainly focused on their host effects. However, very little is known about their interaction with dairy ingredients. Such knowledge could contribute to designing new and more efficient dairy food, and to better understand relationships between milk constituents. The purpose of this review is first to provide an overview of the current knowledge about the biomolecules produced on bacterial surface and the composition of the dairy matter. In order to understand how bacteria interact with dairy molecules, adhesion mechanisms are subsequently reviewed with a special focus on the environmental conditions affecting bacterial adhesion. Methods dedicated to investigate the bacterial surface and to decipher interactions between bacteria and abiotic dairy components are also detailed. Finally, relevant industrial implications of these interactions are presented and discussed.

  19. Surface functionalization of two-dimensional metal chalcogenides by Lewis acid-base chemistry

    Science.gov (United States)

    Lei, Sidong; Wang, Xifan; Li, Bo; Kang, Jiahao; He, Yongmin; George, Antony; Ge, Liehui; Gong, Yongji; Dong, Pei; Jin, Zehua; Brunetto, Gustavo; Chen, Weibing; Lin, Zuan-Tao; Baines, Robert; Galvão, Douglas S.; Lou, Jun; Barrera, Enrique; Banerjee, Kaustav; Vajtai, Robert; Ajayan, Pulickel

    2016-05-01

    Precise control of the electronic surface states of two-dimensional (2D) materials could improve their versatility and widen their applicability in electronics and sensing. To this end, chemical surface functionalization has been used to adjust the electronic properties of 2D materials. So far, however, chemical functionalization has relied on lattice defects and physisorption methods that inevitably modify the topological characteristics of the atomic layers. Here we make use of the lone pair electrons found in most of 2D metal chalcogenides and report a functionalization method via a Lewis acid-base reaction that does not alter the host structure. Atomic layers of n-type InSe react with Ti4+ to form planar p-type [Ti4+n(InSe)] coordination complexes. Using this strategy, we fabricate planar p-n junctions on 2D InSe with improved rectification and photovoltaic properties, without requiring heterostructure growth procedures or device fabrication processes. We also show that this functionalization approach works with other Lewis acids (such as B3+, Al3+ and Sn4+) and can be applied to other 2D materials (for example MoS2, MoSe2). Finally, we show that it is possible to use Lewis acid-base chemistry as a bridge to connect molecules to 2D atomic layers and fabricate a proof-of-principle dye-sensitized photosensing device.

  20. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yuki, E-mail: ynagao@jaist.ac.jp; Kubo, Takahiro

    2014-12-30

    Graphical abstract: - Highlights: • Proton transport of fully protonated poly(aspartic acid) thin film was investigated. • The thin film structure differed greatly from the partially protonated one. • Proton transport occurs on the surface, not inside of the thin film. • This result contributes to biological transport systems such as bacteriorhodopsin. - Abstract: Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120–670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  1. Relation between the secondary structure of carbohydrate residues of alpha1-acid glycoprotein (orosomucoid) and the fluorescence of the protein.

    Science.gov (United States)

    Albani, Jihad R

    2003-05-01

    We studied in this work the relation that exists between the secondary structure of the glycans of alpha(1)-acid glycoprotein and the fluorescence of the Trp residues of the protein. We calculated for that the efficiency of quenching and the radiative and non-radiative constants. Our results indicate that the glycans display a spatial structure that is modified upon asialylation. The asialylated conformation is closer to the protein matrix than the sialylated form, inducing by that a decrease in the fluorescence parameters of the Trp residues. In fact, the mean quantum yield of Trp residues in sialylated and asialylated alpha(1)-acid glycoprotein are 0.0645 and 0.0385, respectively. Analysis of the fluorescence emission of alpha(1)-acid glycoprotein as the result of two contributions (surface and hydrophobic domains) indicates that quantum yields of both classes of Trp residues are lower when the protein is in the asialylated form. Also, the mean fluorescence lifetime of Trp residues decreases from 2.285 ns in the sialylated protein to 1.948 ns in the asialylated one. The radiative rate constant k(r) of the Trp residues in the sialylated alpha(1)-acid glycoprotein is higher than that in the asialylated protein. Thus, the carbohydrate residues are closer to the Trp residues in the absence of sialic acid. The modification of the spatial conformation of the glycans upon asialylation is confirmed by the decrease of the fluorescence lifetimes of Calcofluor, a fluorophore that binds to the carbohydrate residues. Finally, thermal intensity quenching of Calcofluor bound to alpha(1)-acid glycoprotein shows that the carbohydrate residues have slower residual motions in the absence of sialic acid residues.

  2. Acidic Microenvironments in Waste Rock Characterized by Neutral Drainage: Bacteria–Mineral Interactions at Sulfide Surfaces

    Directory of Open Access Journals (Sweden)

    John W. Dockrey

    2014-03-01

    Full Text Available Microbial populations and microbe-mineral interactions were examined in waste rock characterized by neutral rock drainage (NRD. Samples of three primary sulfide-bearing waste rock types (i.e., marble-hornfels, intrusive, exoskarn were collected from field-scale experiments at the Antamina Cu–Zn–Mo mine, Peru. Microbial communities within all samples were dominated by neutrophilic thiosulfate oxidizing bacteria. However, acidophilic iron and sulfur oxidizers were present within intrusive waste rock characterized by bulk circumneutral pH drainage. The extensive development of microbially colonized porous Fe(III (oxyhydroxide and Fe(III (oxyhydroxysulfate precipitates was observed at sulfide-mineral surfaces during examination by field emission-scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM-EDS. Linear combination fitting of bulk extended X-ray absorption fine structure (EXAFS spectra for these precipitates indicated they were composed of schwertmannite [Fe8O8(OH6–4.5(SO41–1.75], lepidocrocite [γ-FeO(OH] and K-jarosite [KFe3(OH6(SO42]. The presence of schwertmannite and K-jarosite is indicative of the development of localized acidic microenvironments at sulfide-mineral surfaces. Extensive bacterial colonization of this porous layer and pitting of underlying sulfide-mineral surfaces suggests that acidic microenvironments can play an important role in sulfide-mineral oxidation under bulk circumneutral pH conditions. These findings have important implications for water quality management in NRD settings.

  3. Detection of glycoprotein using fiber optic surface plasmon resonance sensors with boronic acid

    Science.gov (United States)

    Wang, Fang; Zhang, Yang; Liu, Zigeng; Qian, Siyu; Gu, Yiying; Jing, Zhenguo; Sun, Changsen; Peng, Wei

    2017-04-01

    In this paper, we present a tilted fiber Bragg gratings (TFBG) based surface Plasmon resonance (SPR) label-free sensors with boronic acid derivative (ABA-PBA) as receptor molecule to detect glycoprotein with high sensitivity and selectivity. Tilted fiber Bragg gratings (TFBG) as a near infrared wavelengths detecting element can be able to excite a number of cladding modes whose properties can be detected accurately by measuring the variation of transmitted spectra. A 10° TFBG coated by 50nm gold film was manufactured to stimulate surface plasmon resonance on the surface of the sensor. The sensor was loaded with boronic acid derivative as the recognition molecule which has been widely used in various areas for the recognition matrix of diol-containing biomolecules. The proposed TFBG-SPR sensors exhibit good selectivity and repeatability with the protein concentration sensitivity up to 2.867dB/ (mg/ml) and the limit of detection was 2*10-5g/ml.

  4. Surface Resistance of Jute Fibre/Polylactic Acid Biocomposite to Wet Heat

    Science.gov (United States)

    Zandvliet, Clio; Bandyopadhyay, N. R.; Ray, Dipa

    2016-04-01

    Jute fibre/polylactic acid (PLA) composite is of special interest because both resin and reinforcement come from renewable resources. Thus, it could be a more eco-friendly alternative to glass fibre composite [1] and to conventional wood-based panels made with phenol-formaldehyde resin which present many drawbacks for the workers and the environment [2]. Yet the water affinity of the natural fibres, the susceptibility of PLA towards hydrolysis and the low glass transition of the PLA raise a question about the surface resistance of such composites to wet heat in service condition for a furniture application [3]. In this work, the surface resistance of PLA/jute composite alone and with two different varnishes are investigated in regard to an interior application following the standard test method in accordance to BS EN 18721:2009: "Furniture: assessment of surface resistance to wet heat". It is compared to two common wood based panels, plywood and hardboard. After test, the composite material surface is found to be more affected than plywood and hardboard, but it becomes resistant to wet heat when a layer of biosourced varnish or petrol-based polyurethane varnish are applied on the surface.

  5. Poly(acrylic acid) brushes pattern as a 3D functional biosensor surface for microchips

    Science.gov (United States)

    Wang, Yan-Mei; Cui, Yi; Cheng, Zhi-Qiang; Song, Lu-Sheng; Wang, Zhi-You; Han, Bao-Hang; Zhu, Jin-Song

    2013-02-01

    Poly(acrylic acid) (PAA) brushes, a novel three dimensional (3D) precursor layer of biosensor or protein microarrays, possess high protein loading level and low non-specific protein adsorption. In this article, we describe a simple and convenient way to fabricate 3D PAA brushes pattern by microcontact printing (μCP) and characterize it with FT-IR and optical microscopy. The carboxyl groups of PAA brushes can be applied to covalently immobilize protein for immunoassay. Thriving 3D space made by patterning PAA brushes thin film is available to enhance protein immobilization, which is confirmed by measuring model protein interaction between human immunoglobulin G (H-IgG) and goat anti-H-IgG (G-H-IgG) with fluorescence microscopy and surface plasmon resonance imaging (SPRi). As expected, the SPRi signals of H-IgG coating on 3D PAA brushes pattern and further measuring specific binding with G-H-IgG are all larger than that of 3D PAA brushes without pattern and 2D bare gold surface. We further revealed that this surface can be used for high-throughput screening and clinical diagnosis by label-free assaying of Hepatitis-B-Virus surface antibody (HBsAb) with Hepatitis-B-Virus surface antigen (HBsAg) concentration array chip. The linearity range for HBsAb assay is wider than that of conventional ELISA method.

  6. Effect of citric acid, tetracycline, and doxycycline on instrumented periodontally involved root surfaces: A SEM study

    Directory of Open Access Journals (Sweden)

    Gurparkash Singh Chahal

    2014-01-01

    Full Text Available Background: A surface smear layer consisting of organic and inorganic material is formed on the root surface following mechanical instrumentation and may inhibit the formation of new connective tissue attachment to the root surface. Modification of the tooth surface by root conditioning has resulted in improved connective tissue attachment and has advanced the goal of reconstructive periodontal treatment. Aim: The aim of this study was to compare the effects of citric acid, tetracycline, and doxycycline on the instrumented periodontally involved root surfaces in vitro using a scanning electron microscope. Settings and Design: A total of 45 dentin samples obtained from 15 extracted, scaled, and root planed teeth were divided into three groups. Materials and Methods: The root conditioning agents were applied with cotton pellets using the "Passive burnishing technique" for 5 minutes. The samples were then examined by the scanning electron microscope. Statistical Analysis Used: The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows. For all quantitative variables means and standard deviations were calculated and compared. For more than two groups ANOVA was applied. For multiple comparisons post hoc tests with Bonferroni correction was used. Results: Upon statistical analysis the root conditioning agents used in this study were found to be effective in removing the smear layer, uncovering and widening the dentin tubules and unmasking the dentin collagen matrix. Conclusion: Tetracycline HCl was found to be the best root conditioner among the three agents used.

  7. Adsorption properties of trifluoroacetic acid on anatase (101) and (001) surfaces: a density functional theory study.

    Science.gov (United States)

    Lamiel-Garcia, Oriol; Fernandez-Hevia, Daniel; Caballero, Amador C; Illas, Francesc

    2015-09-28

    The interaction of trifluoroacetic acid with anatase TiO2(101) and TiO2(001) surfaces has been studied by means of periodic density functional theory based calculations. On the former, the interaction is weak with the adsorbed molecules in a configuration almost indistinguishable from the gas phase structure. On the latter, the interaction is very strong; the molecule adsorbs as trifluoroacetate and releases a proton that binds an oxygen surface atom with a significant distortion of the substrate. The difference in adsorption the mode and strength can be understood from the different structural features of both surfaces and provides arguments to the role of trifluoroacetic as a morphological control agent in the solvothermal synthesis of TiO2 nanoparticles with predominant (001) facets. This, in turn, has a very significant impact on industrial production strategies of value-added TiO2 for photocatalytic applications. Analysis of calculated core level binding energies for F(1s) confirms the experimental assignment to F at the surface as F(-) at Ti surface sites and to F in -CF3 groups of the adsorbed molecule.

  8. Effects of rice harvest moisture on kernel damage and milled rice surface free fatty acid levels.

    Science.gov (United States)

    Parker, Amanda M; Proctor, Andrew; Eason, Robert L; Jain, Vishal

    2007-01-01

    Surface free fatty acid (FFA) on milled rice is a key factor in determining rice quality and acceptability to the brewing industry. Rice FFA oxidizes, causing off-flavors and odors to develop, compromising the brewing quality of milled rice. The effect of harvest moisture (13%, 16%, and 20%), harvester type (1688 Case and 9500 John Deere), and rice variety (Cocodrie and Bengal) on harvest damaged rough rice and milled rice surface FFA after drying to 12% moisture and 6 mo rough rice storage was examined. The Case harvester produced more damaged kernels than the John Deere harvester, but this was not reflected in surface FFA development. There were no significant FFA differences in variety or harvester type. Rice harvested at a higher moisture content (20%) produced significantly greater FFA values, with a peak near 0.1%, than rice harvested at lower moisture contents (13% and 16%), which had FFA values near 0.08%. Retention of bran by damaged kernels at high harvest moisture probably was responsible for promoting surface FFA development, but if bran was lost at lower harvest moistures, surface FFA, development was limited. Harvest moisture affected milled rice FFA, although rough rice was dried to 12% immediately after harvesting.

  9. Surface and line-edge roughness in acid-breakable resin-based positive resist

    Science.gov (United States)

    Sakamizu, Toshio; Shiraishi, Hiroshi

    2003-06-01

    A positive chemical amplification resist based on acid-catalyzed fragmentation of acetal groups in its main-chain has been developed as a means for reducing line-edge roughness. The resist consists of an acid-generator, an acid-diffusion controller and an acid-breakable (AB) resin that is synthesized through a co-condensation reaction between polyphenol and aromatic multi-functional vinylether compound. The effects of the fractionation of AB resins on resin properties and line-edge roughness (LER) are evaluated. Although AB resins have wide molecular-weight distributions, the density of acetal groups in this AB resin is found to be almost constant except in the lower molecular-weight components. The resist with a fractionated resin from which such components removed provides the high resolution of 60-nm line-and-space (L/S) patterns with fairly low LER. AFM analysis shows the surface roughness (SR) for the resist with the fractionated resin is smaller than that for a resist using non-fractionated AB resin, and that the SR value is not altered throughout the range of exposure doses up to just below the beginning of dissolution. By using the fractionated AB resin, the AB resin-based resist (ABR) is capable of forming sub-100 nm L/S patterns with less than 5 nm of LER (3σ).

  10. Tuning the Band Bending and Controlling the Surface Reactivity at Polar and Nonpolar Surfaces of ZnO through Phosphonic Acid Binding.

    Science.gov (United States)

    McNeill, Alexandra R; Hyndman, Adam R; Reeves, Roger J; Downard, Alison J; Allen, Martin W

    2016-11-16

    ZnO is a prime candidate for future use in transparent electronics; however, development of practical materials requires attention to factors including control of its unusual surface band bending and surface reactivity. In this work, we have modified the O-polar (0001̅), Zn-polar (0001), and m-plane (101̅0) surfaces of ZnO with phosphonic acid (PA) derivatives and measured the effect on the surface band bending and surface sensitivity to atmospheric oxygen. Core level and valence band synchrotron X-ray photoemission spectroscopy was used to measure the surface band bending introduced by PA modifiers with substituents of opposite polarity dipole moment: octadecylphosphonic acid (ODPA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctylphosphonic acid (F13OPA). Both PAs act as surface electron donors, increasing the downward band bending and the strength of the two-dimensional surface electron accumulation layer on all of the ZnO surfaces investigated. On the O-polar (0001̅) and m-plane (101̅0) surfaces, the ODPA modifier produced the largest increase in downward band bending relative to the hydroxyl-terminated unmodified surface of 0.55 and 0.35 eV, respectively. On the Zn-polar (0001) face, the F13OPA modifier gave the largest increase (by 0.50 eV) producing a total downward band bending of 1.00 eV, representing ∼30% of the ZnO band gap. Ultraviolet (UV) photoinduced surface wettability and photoconductivity measurements demonstrated that the PA modifiers are effective at decreasing the sensitivity of the surface toward atmospheric oxygen. Modification with PA derivatives produced a large increase in the persistence of UV-induced photoconductivity and a large reduction in UV-induced changes in surface wettability.

  11. Photoresponsive surface molecularly imprinted polymer on ZnO nanorods for uric acid detection in physiological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Qian [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Department of Science and Environmental Studies, The Hong Kong Institute of Education (Hong Kong); Li, Zai-yong; Wei, Yu-bo; Yang, Xia; Liu, Lan-tao [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Gong, Cheng-bin, E-mail: gongcbtq@swu.edu.cn [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Ma, Xue-bing [The Key Laboratory of Applied Chemistry of Chongqing Municipality, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Lam, Michael Hon-wah [Department of Biology and Chemistry, City University of Hong Kong (Hong Kong); Chow, Cheuk-fai, E-mail: cfchow@ied.edu.hk [Department of Science and Environmental Studies, The Hong Kong Institute of Education (Hong Kong)

    2016-09-01

    A photoresponsive surface molecularly imprinted polymer for uric acid in physiological fluids was fabricated through a facile and effective method using bio-safe and biocompatible ZnO nanorods as a support. The strategy was carried out by introducing double bonds on the surface of the ZnO nanorods with 3-methacryloxypropyltrimethoxysilane. The surface molecularly imprinted polymer on ZnO nanorods was then prepared by surface polymerization using uric acid as template, water-soluble 5-[(4-(methacryloyloxy)phenyl)diazenyl]isophthalic acid as functional monomer, and triethanolamine trimethacryl ester as cross-linker. The surface molecularly imprinted polymer on ZnO nanorods showed good photoresponsive properties, high recognition ability, and fast binding kinetics toward uric acid, with a dissociation constant of 3.22 × 10{sup −5} M in aqueous NaH{sub 2}PO{sub 4} buffer at pH = 7.0 and a maximal adsorption capacity of 1.45 μmol g{sup −1}. Upon alternate irradiation at 365 and 440 nm, the surface molecularly imprinted polymer on ZnO nanorods can quantitatively uptake and release uric acid. - Highlights: • Novel surface molecularly imprinted polymer on ZnO nanorods was synthesized. • ZnO-SMIP showed good selectivity toward uric acid in physiological fluids. • ZnO-SMIP displayed good photoresponsive properties.

  12. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    Science.gov (United States)

    Nagao, Yuki; Kubo, Takahiro

    2014-12-01

    Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120-670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  13. Recommended Correlations for the Surface Tension of Aliphatic, Carboxylic, and Polyfunctional Organic Acids

    Science.gov (United States)

    Mulero, A.; Cachadiña, I.; Sanjuán, E. L.

    2016-09-01

    In previous papers, we have proposed specific correlations to reproduce the surface tension values for several sets of fluids and for wide ranges of temperatures. In this paper, we focus our attention on organic fatty (aliphatic, carboxylic, and polyfunctional) acids. We have taken into account the available data and values in the DIPPR and DETHERM databases and also Wohlfarth and Wohlfarth's (1997) book. In some cases we have also considered new data published elsewhere. All the data and values have been carefully filtered and subsequently fitted with the use of the model currently implemented in NIST's REFPROP program, calculating two or four adjustable coefficients for each fluid. As a result, we propose recommended correlations for 99 acids, providing mean absolute percentage deviations below 1.6% in all cases.

  14. Enhancing phosphate adsorption capacity of SDS-based magnetite by surface modification of citric acid

    Science.gov (United States)

    Yu, Zhigang; Zhang, Chang; Zheng, Zuhong; Hu, Liang; Li, Xuemei; Yang, Zhongzhu; Ma, Chi; Zeng, Guangming

    2017-05-01

    In this study, citric acid (CA) was employed as a low-molecule organic acid to influence the adsorption performance of phosphorus by as-obtained magnetite. The factors including initial phosphate concentrations, dosage of citric acid, pH value, ion strength, contact time and temperature were examined in detail. Results indicated that the dissolution of anion sodium dodecyl sulfate (SDS) covering on surface of magnetite, a slight decrease of Fe level and a superior structure of magnetite after CA modification occurred. The pH-dependence of phosphate adsorption was impeded and the surface potential of magnetite positively increased at pH > 5.0 when CA was added. Non-linear regression Langmuir-Freundlich model was fitted well in thermodynamics, and the opposite adsorption process as a function of temperatures with or without CA addition was due to the decrease of active energy and active mobility of phosphate ion. Finally, the declining adsorption efficiency with increasing cycles was observed while phosphate removal was approximately finished and had small change with 0.05 and 0.1 M of CA addition. Those improvements of removal efficiency of phosphorus by modified iron oxide were because of the removal of anionic SDS that increased the surface positive charge, and especially the dissolution of element Fe into solution to form precipitate with phosphorus ions. The enhanced stability of magnetite by CA also promoted the high removal efficiency of phosphorus. These implications of CA on phosphate removal can be extended to the field where phosphate pollution is notorious but urgent.

  15. Influence of surface modification of SrFe12O19 particles with oleic acid on magnetic microsphere preparation

    Institute of Scientific and Technical Information of China (English)

    Sifang Kong; Peipei Zhang; Xiufang Wen; Pihui Pi; Jiang Cheng; Zhuoru Yang; Jing Hai

    2008-01-01

    Oleic acid was used as surface modification agent to improve the hydrophobicity of magnetic strontium hexaferrite particles. The structure and properties of treated magnetic particles were characterized by scanning electronic microscopy (SEM), Fourier transform infrared spectra (FTIR), powder X-ray diffraction (XRD) and magnetic property measurement system (MPMS). The results show that oleic acid is chemically enwrapped on the surface of SrFe12O19 particles. Magnetic particles modified by oleic acid are highly dispersible and strongly responsive to magnetism but with slight decrease in saturated magnetization. The affinity between magnetic particles and monomers is improved by surface modification, resulting in increased particle incorporation in magnetic polymeric microspheres. The surface modification mechanism of magnetic particles by oleic acid is addressed in this work.

  16. Characterization of Bronze Surface Layer Formed by Microarc Oxidation Process in 12-Tungstophosphoric Acid

    Directory of Open Access Journals (Sweden)

    Zoran Nedić

    2009-12-01

    Full Text Available This paper is a brief review of our recent research into novel uses for heteropoly compounds as precursors for thin films that can be used as catalysts and materials with good optical, conductive and other characteristics. In view of this, we have chosen thin film obtained with 12-tungsphosphoric acid on aluminum substrates. In all cases, a relatively new, microarc oxidation technique has been used to prepare oxide coatings on substrate surfaces. Advanced physicochemical methods, AFM and SEM-EDS, XRD, Raman and Micro-Raman, and luminescence spectroscopy, as the most powerful techniques, have been used for the characterization of new materials. Possible applications have been discussed as well.

  17. Oxidation and etching behaviors of the InAs surface in various acidic and basic chemical solutions

    Science.gov (United States)

    Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo

    2017-04-01

    Indium arsenide (InAs) is the candidate of choice as a new channel material for application in future technologies beyond the Si-based electronic devices because it has a much higher electron mobility than silicon. In this study, the oxidation and etching behaviors of InAs (100) in various acidic and basic solutions, such as HF, HCl, H2SO4, NaOH, KOH, and NH4OH, were investigated. In addition, the effect of pH on the oxidation and etching reactions taking place on the InAs surface was studied using solutions with a pH ranging from 1 to 13. It was observed that the oxidation of the InAs surface was hindered in acidic solutions, which was attributed to the dissolution of the oxidized surface layer. In particular, the treatment of the InAs surface using a strongly acidic solution with a pH of less than 3 produced an oxide-free surface due to the predominant etching of the InAs surface. The addition of H2O2 to the acidic solutions greatly increased the etching rate of the InAs surface, which suggests that the oxidation process is the rate-limiting step in the sequence of reactions that occur during the etching of the InAs surface in acidic solutions. The etching of InAs was suppressed in neutral solutions, which resulted in the formation of a relatively thicker oxide layer on the surface, and mild etching of the InAs surface took place in basic solutions. However, in basic solutions, the addition of H2O2 did not significantly contribute to the increase of the oxidation state of the InAs surface; thus, its effect on the etching rate of InAs was smaller than in acidic solutions.

  18. Surface modification of hydroxyapatite nanocrystals by grafting polymers containing phosphonic acid groups.

    Science.gov (United States)

    Choi, Hyung Woo; Lee, Hong Jae; Kim, Kyung Ja; Kim, Hyun-Min; Lee, Sang Cheon

    2006-12-01

    A novel approach for the surface modification of hydroxyapatite (HAp) nanocrystals is described by grafting polymerization of vinyl phosphonic acid (VPA) using a redox initiating system in an aqueous media. Fourier transform infrared (FT-IR) and XRD analyses confirmed the modification reaction on HAp surfaces. Inductively coupled plasma mass spectroscopy (ICP MS) showed that the Ca/P molar ratio decreased from 1.67 to 1.36 with increasing the feed VPA amount. Zeta potentials of unmodified HAp and modified HAp in phosphate-buffered saline (PBS) solutions (pH 7.4, ionic strength = 10 mM) were negative and decreased with increasing the amount of grafted PVPA. Transmission electron microscopy (TEM) measurements and time-dependent phase monitoring indicated that the colloidal stability of modified HAp over unmodified HAp in water dramatically increased and tended to exist as single nanocrystals without aggregation.

  19. Assessment of perfluorooctanoic acid and perfluorooctane sulfonate in surface water - Tamil Nadu, India.

    Science.gov (United States)

    Sunantha, Ganesan; Vasudevan, Namasivayam

    2016-08-15

    As an emerging class of environmentally persistent organic pollutants, perfluorinated compounds (PFCs), particularly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS); have been universally found in the environment. Wastewater and untreated effluents are likely the major causes for the accumulation of PFCs in surface water. There are very few reports on the contamination of PFCs in the developing countries, particularly in India. This study reports the quantitative analysis of PFOA and PFOS in Noyyal, Cauvery, and also lakes in and around Chennai, using Ultra-Fast liquid chromatograph. The concentration of PFOA and PFOS ranged from 4 to 93ng/L and 3 to 29ng/L, respectively. The concentration of PFOS was below detectable limit in Cauvery River. A reliable concentration of PFOA was recorded at all sites of River Cauvery (5ng/L). The present study could be useful for the assessment of future monitoring programs of PFOA and PFOS in the surface water.

  20. Oxidation of formic acid on the Pt(111) surface in the gas phase.