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81.
Mutkus L Aschner JL Syversen T Shanker G Sonnewald U Aschner M 《Biological trace element research》2006,109(3):267-280
Glutamate is removed mainly by astrocytes from the extracellular fluid via high-affinity astroglial Na+-dependent excitatory amino acid transporters, glutamate/aspartate transporter (GLAST), and glutamate transporter-1 (GLT-1).
Mercuric chloride (HgCl2) is a highly toxic compound that inhibits glutamate uptake in astrocytes, resulting in excessive extracellular glutamate
accumulation, leading to excitotoxicity and neuronal cell death. The mechanisms associated with the inhibitory effects of
HgCl2 on glutamate uptake are unknown. This study examines the effects of HgCl2 on the transport of 3H-d-aspartate, a nonmetabolizable glutamate analog, using Chinese hamster ovary cells (CHO) transfected with two glutamate transporter
subtypes, GLAST (EAAT1) and GLT-1 (EAAT2), as a model system. Additionally, studies were undertaken to determine the effects
of HgCl2 on mRNA and protein levels of these transporters. The results indicate that (1) HgCl2 leads to significant (p<0.001) inhibition of glutamate uptake via both transporters, but is a more potent inhibitor of glutamate transport via GLAST
and (2) the effect of HgCl2 on inhibition of glutamate uptake in transfected CHO cells is not associated with changes in transporter protein levels despite
a significant decrease in mRNA expression; thus, (3) HgCl2 inhibition is most likely related to its direct binding to the functional thiol groups of the transporters and interference
with their uptake function. 相似文献
82.
Recently attempts have been made to establish the presence and to determine the metabolic versatility of microorganisms in
the terrestrial deep subsurface at the Savannah River Plant, Aiken, SC, USA. Sediment samples obtained at 20 different depths
of up to 526 m were examined to determine carbon mineralization under aerobic, sulfate-reducing, and methanogenic conditions.
The evolution of14CO2 from radiolabelled glucose was observed under aerobic conditions in all sediments, whereas pyridine was transformed in 50%
of the 20 sediments and indole was metabolized in 85% of the sediments. Glucose mineralization in certain sediments was comparable
to that in the surface environment. Sulfate was reduced in only five sediments, and two were carbon limited. Methane production
was detected in ten sediments amended with formate only after long-term incubations. The transformation of indole and pyridine
was only rarely observed under sulfate-reducing conditions and was never detected in methanogenic incubations. This study
provides information concerning the metabolic capability of both aerobic and anaerobic microorganisms in the deep subsurface
and may prove useful in determining the feasibility of microbial decontamination of such environments. 相似文献
83.
Vasant Chellappa Kendra N. Taylor Kathryn Pedrick Carlos Donado Ilka Arun Netravali Khaleda Haider Annaiah Cariappa Natasha F. Dalomba Shiv Pillai 《PloS one》2013,8(1)
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. 相似文献
84.
85.
Three iridoid glycosides 6-O-(3'-O-benzoyl)-alpha-l-rhamnopyranosylcatalpol (1a), 6-O-(3'-O-trans-cinnamoyl)-alpha-l-rhamnopyranosylcatalpol (2a) and 6-O-(3'-O-cis-cinnamoyl)-alpha-l-rhamnopyranosylcatalpol (3a) were isolated from aerial parts of Gmelina arborea and structures were elucidated by spectral analysis. Additionally a known iridoid 6-O-(3', 4'-O-dibenzoyl)-alpha-l-rhamnopyranosylcatalpol (4) was also isolated and identified. 相似文献
86.
A solid state fermentation (SSF) method was used to produce citric acid by Aspergillus niger DS 1 using sugarcane bagasse as a carrier and sucrose or molasses based medium as a moistening agent. Initially bagasse and wheat bran were compared as carrier. Bagasse was the most suitable carrier, as it did not show agglomeration after moistening with medium, resulting in better heat and mass transfer during fermentation and higher product yield. Different parameters such as moisture content, particle size, sugar level and methanol concentration of the medium were optimised and 75% moisture level, 31.8 g sugar/100 g dry solid, 4% (v/w) methanol and particles of the size between 1.2 and 1.6 mm were found to be optimal. Sucrose and clarified and non-clarified molasses medium were also tested as moistening agents for SSF and under optimised conditions, 20.2, 19.8 and 17.9 g citric acid /100 g of dry solid with yield of 69.6, 64.5 and 62.4% (based on sugar consumed) was obtained in sucrose, clarified and non-clarified molasses medium respectively, after 9 days of fermentation. 相似文献
87.
Narasaraju T Sim MK Ng HH Phoon MC Shanker N Lal SK Chow VT 《Microbes and infection / Institut Pasteur》2009,11(1):2-11
Most pandemic influenza virus strains undergo adaptation or reassortment before they acquire the ability to cause fatal infections in a new host species. The pathologic changes and tissue tropism during virus adaptation are not fully understood. Here we investigated pathologic changes and tissue tropism by serial lung-to-lung passaging of human influenza virus strain A/Aichi/2/68 (H3N2) in a BALB/c mouse model. Enhanced pulmonary lesions and systemic virus infection were observed during adaptation. Late passage 10 (P10) virus caused extra-pulmonary spread with necrotic and inflammatory lesions in the brain, heart, spleen and intestine of infected animals, in contrast to infection with earlier passage viruses which were restricted to lungs. Non-conservative mutations in the hemagglutinin (Gly218Glu) and non-structural 1 (Asp125Gly) proteins were identified in P10 virus which exhibited high virulence. Virus growth kinetics showed enhanced replication ability of P10 virus in different cell lines. P10 virus also exhibited the ability to bind to erythrocytes of different host species. These results demonstrate extra-pulmonary spread of influenza virus during adaptation with enhanced replication ability in a new host. This mouse adaptation model may provide a basis for understanding cross-species adaptability corresponding to increased virulence of the influenza A virus, a phenomenon of relevance to the emergence of future highly pathogenic strains. 相似文献
88.
89.
Background
Surface waters quality has declined in developing countries due to rapid industrialization and population growth. The microbiological quality of river Ganga, a life-sustaining surface water resource for large population of northern India, is adversely affected by several point and non-point sources of pollution. Further, untreated surface waters are consumed for drinking and various household tasks in India making the public vulnerable to water-borne diseases and outbreaks. Enterococci, the 'indicator' of water quality, correlates best with the incidence of gastrointestinal diseases as well as prevalence of other pathogenic microorganisms. Therefore, this study aims to determine the distribution of species diversity, dissemination of antimicrobial-resistance and virulence-markers in enterococci with respect to rural-urban landscape along river Ganga in northern India. 相似文献90.
Aim: To develop quantitative PCR for culture‐independent enumeration of enterotoxigenic Escherichia coli (ETEC) in sewage‐impacted waters and aquatic weeds. Methods and Results: Two fluorescent probes (TaqMan and FRET) based on two different real‐time PCR chemistries were designed in highly conserved region of LT1 gene encoding heat labile enterotoxin. Both the assays could detect 2 CFU ml?1 from serially diluted (two‐fold and ten‐fold) culture of reference strain (E. coli MTCC 723). FRET performed better in terms of CT value and PCR efficiency than TaqMan. The presence of 106 CFU ml?1 of nonpathogenic E. coli reduced the detection limit two‐fold with both the probes. However, the performance for two chemistries in various environmental samples was significantly (student’s t‐test, P < 0·05) different. Conclusion: It could be inferred from this study that real‐time PCR chemistries (TaqMan and FRET) could detect very few copies of target DNA in pure cultures, but may give varied response in the presence of nonspecific DNA and natural inhibitors present in environmental sample matrices. Significance and Impact of the Study: The assays can be used for pre‐emptive monitoring of aquatic weeds (a potential nonpoint source), surface and potable waters to prevent waterborne outbreaks caused by ETEC. 相似文献