Incomplete information about AIDS on Chinese websites.
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Acquired Immunodeficiency Syndrome↗
Biomedical subjects
A Zhang
Publications and source records attributed to A Zhang.
Morphological study of endothelial cells during freezing.
Microvascular injury is recognized as a major tissue damage mechanism of ablative cryosurgery. Endothelial cells lining the vessel wall are thought to be the initial target of freezing. However, details of this injury mechanism are not yet completely understood. In this study, ECMatrix 625 was used to mimic the tumour environment and to allow the endothelial cells cultured in vitro to form the tube-like structure of the vasculature. The influence of water dehydration on the integrity of this structure was investigated. It was found that the initial cell shape change was mainly controlled by water dehydration, dependent on the cooling rate, resulting in the shrinkage of cells in the direction normal to the free surface. As the cooling was prolonged and temperature was lowered, further cell shape change could be induced by the chilling effects on intracellular proteins, and focal adhesions to the basement membrane. Quantitative analysis showed that the freezing induced dehydration greatly enhanced the cell surface stresses, especially in the axial direction. This could be one of the major causes of the final breaking of the cell junction and cell detachment.
Actins↗
Intra-ethnic differences in genetic variants of the UGT-glucuronosyltransferase 1A1 gene in Chinese populations.
Variants within the human UGT1A1 gene are associated with irinotecan induced severely adverse reactions and hyperbilirubinemia. Intra-ethnic differences in the genetic variation and haplotypes of UGT1A1 gene have been analyzed in the present study. Relationship between the concentrations of total serum bilirubin (T-bil) and haplotype structure of UGT1A1 in healthy people were also evaluated. We genotyped five functional polymorphisms including -3279T>G and -3156G>A in the enhancer region, (TA)6>7 in the TATA box, and 211G>A (G71R), 686C>A (P229Q) in the exon1 region of UGT1A1 in three groups of healthy Chinese ethnic populations, consisting of 264 subjects of She origin, 539 of Han origin and 273 of Dong origin. The distribution of -3279T>G, (TA)6>7, 211G>A of UGT1A1 differed greatly as between the three ethnic groups. All of six haplotypes differed considerably between at least two of the three groups, which highlighted the need to analyze clinically irinotecan toxicity relevant SNPs and haplotypes in a variety of different racial groups within the Chinese population. Total bilirubin concentration in homozygous carriers of the -3279G and (TA)7 allele were significantly higher than those in heterozygous carriers or homozygous carriers of wild-type alleles. Carriers of the variant haplotypes (-3279G; -3156A; (TA)7; 211G; 686C) had higher serum T-Bil concentrations compared with the other groups. Our results indicate that heterogeneity among different ethnic populations is possibly the result of microevolution and is relevant to studies into the effect of tailored drug treatment.
Adult↗
Inhibition of telomerase enhances apoptosis induced by sodium butyrate via mitochondrial pathway.
Telomerase activation represents an early step in carcinogenesis. Increased telomerase activity in cervical cancer suggests a potential target for the development of novel therapeutic drugs. The aim of this study is to investigate the impact of telomerase activity on the biological features of HeLa cells and the possible mechanisms of enhanced apoptosis rate induced by sodium butyrate after telomerase inhibition. We introduced vectors encoding dominate negative (DN)-hTERT, wild-type (WT)-hTERT, or a control vector expressing only a drug-resistance marker into HeLa cells. Thus we assessed the biological effects of telomerase activity on telomere length, cell proliferation, chemosensitivity and radiosensitivity. In order to understand the mechanisms in which DN-hTERT enhances the apoptosis induced by sodium butyrate, we detected the release status of cytochrome c and apoptosis inducing factor (AIF) from mitochondria. Ectopic expression of DN-hTERT resulted in inhibition of telomerase activity, reduction of telomere length, decreased colony formation ability, and loss of tumorigenicity in nude mice. Moreover, DN-hTERT transfected HeLa cells with shortened telomeres were more susceptible to multiple chemotherapeutic agents and radiation. WT-hTERT transfected HeLa cells with longer telomeres exhibited resistance to radiation and chemotherapeutic agents. Our data demonstrate that elevated release level of cytochrome c and AIF from mitochondria might contribute to the enhanced apoptosis in DN-hTERT transfected HeLa cells after treatment with sodium butyrate. Inhibition of telomerase might serve as a promising adjunctive therapy combined with conventional therapy in cervical cancer.
Animals↗
A novel cationic cardiolipin analogue for gene delivery.
The optically active R and S isomers of cationic cardiolipin analogues (CCA) were synthesized and evaluated as a liposome based transfection reagent. Both isomers form stable liposomes with mean diameters of about 120 nm without any additional lipid ingredients. No significant change in particle size distribution profile was observed over one-month storage at room temperature (20-25 degrees C). The gel to liquid crystalline phase transition temperature (Tm) of cationic liposomes comprised of both R and S isomers was approximately 2 degrees C, as measured by differential scanning calorimetry (DSC). Both isomers also formed stable liposomes when combined with DOPE. In vitro transfection efficiency of the CCA/DOPE liposomes complexed to plasmid DNA was evaluated using a luciferase reporter gene. Both liposomes composed of R and S isomers of the cationic cardiolipin displayed higher transfection efficiency than commercially available Lipofectin. Further in vivo studies are warranted.
Animals↗
Biomarkers of cadmium and arsenic interactions.
Advances in proteomics have led to the identification of sensitive urinary biomarkers of renal dysfunction that are increasingly used in toxicology and epidemiology. Recent animal data show that combined exposure to inorganic arsenic (As) and cadmium (Cd) gives rise to more pronounced renal toxicity than exposure to each of the agents alone. In order to examine if similar interaction occurs in humans, renal dysfunction was studied in population groups (619 persons in total) residing in two metal contaminated areas in China: mainly a Cd contaminated area in Zhejiang province (Z-area) and mainly a As contaminated area in Guizhou province (G-area). Nearby control areas without excessive metal exposure were also included. Measurements of urinary beta(2)-microglobulin (UB2MG), N-acetyl-beta-glucosaminidase (UNAG), retinol binding protein (URBP) and albumin (UALB) were used as markers of renal dysfunction. Urinary Cd (UCd) and total As (UTAs) were analyzed by graphite-furnace atomic absorption spectrometry. Urinary inorganic As and its mono- and di-methylated metabolites (UIAs) were determined by Hydride generation. Results. As expected, the highest UCd values occurred in Z-area (Geometric mean, GM 11.6 microg/g crea) while the highest UTAs values occurred in G-area (GM = 288 microg/g crea). Statistically significant increases compared to the respective control area were present both for UTAs, UCd and for UB2MG, UNAG and UALB in Z-area as well as in G-area. UIAs was determined only in Z area. In G-area, there was a clear dose-response pattern both in relation to UTAs and UCd for each of the biomarkers of renal dysfunction. An interaction effect between As and Cd was demonstrated at higher levels of a combined exposure to As and Cd enhancing the effect on the kidney. In Z-area an increased prevalence of B2MG-uria, NAG-uria and ALB-uria was found in relation to UCd, but no relationship to UTAs was found. A statistically significant relationship between UIAs and UB2MG was found among women in this area and an interaction between As and Cd was indicated for B2MG. Conclusion. The present studies, which employed sensitive biomarkers of renal dysfunction, give support to the idea that human co-exposure to Cd and inorganic arsenic gives rise to more pronounced renal damage than exposure to each of the elements alone, but further studies are needed to establish and clarify this interaction.
Acetylglucosaminidase↗
A gene (pks2) encoding a putative 6-methylsalicylic acid synthase from Glarea lozoyensis.
A gene that encodes for a polyketide synthase (PKS) was cloned from the fungus Glarea lozoyensis and characterized. The gene (pks2) consists of four exons interrupted by three introns of 51, 59, and 65 bp, which are clustered at the 5' end. Its predicted product is a 1791-amino-acid protein containing five catalytic motifs typical of fungal PKSs, including a beta-ketosynthase, an acyltransferase, a dehydratase, a beta-ketoacyl reductase, and an acyl carrier region. The gene is transcribed from an initiation site located 375 bp upstream of the translational start codon and extends to a transcriptional termination site 244 bp downstream of the translational stop codon. The gene function is not required for either vegetative growth of G. lozoyensis or for production of pneumocandin, as shown by Agrobacterium-mediated pks2 gene disruption. Previously reported cluster analysis of ketosynthase motifs from 37 fungal polyketide synthases had grouped the Pks2p from G. lozoyensis with PKSs involved in the biosynthesis of 6-methylsalicylic acid. To verify the function of the gene, it was transferred into Aspergillus nidulans under the control of the trpC promoter. 5'-and 3'-RACE experiments confirmed that it was transcribed in the heterologous host, and was associated with the synthesis of a compound identified as 6-methylsalicylic acid by NMR and mass spectrometry. In G. lozoyensis, pks2 is flanked by a gene that encodes a putative drug resistance efflux pump. The Aspergillus pks2 transformants, which were arginine prototrophs, also exhibited precocious pigmentation and accumulated a benzophenone that appeared to be a precursor of emericellin (variecoxanthone B), a known product of A. nidulans. The buildup of the benzophenone may be related to the use of an alternative splice site for the removal of intron 1 of the pks2 transcript in the heterologous host.
Acyltransferases↗
Study of non-uniform nanoparticle liposome extravasation in tumour.
The effect of hyperthermia on the nanoparticle extravasation in different tumour regions was investigated in real time using confocal laser scanning microscopy. Murine mammary carcinoma 4T1 was implanted in the nude mice dorsal skin-fold window chamber. Tumour angiogenesis was observed through the window chamber on days 4, 7, 8 and 10 after the implantation. In 10 days, the tumour became 1-2 mm in diameter and 150 microm thick. Most vessels were found to be <15 microm in diameter. Histological examination showed that there were fewer vessels in a more ordered branching pattern inside the tumour than in the tumour periphery. After hyperthermia at 42 degrees C for 1 h, numerous erythrocytes were found in the peripheral region. Extravasation of rhodamine-labelled 100 nm nanoparticles in different tumour regions under both normal and hyperthermic conditions (34 and 42 degrees C) was quantified using confocal fluorescence microscopy. The relative fluorescence intensity hardly changed in tissue at 34 degrees C, but increased by the local hyperthermia at 42 degrees C. In particular, the relative intensity in the tumour periphery was more than 120 as compared to 40 in the tumour centre, after 1 h hyperthermia. Results showed that the thermally induced liposome nanoparticle extravasation was heterogeneous in tumour, owing to the non-uniform distribution of tumour vasculature. Further, the degree of vascular damage was found to be more severe in the tumour periphery, which is likely due to the high thermal sensitivity of newly formed tumour vessels in this region.
Animals↗
Study of SARS transmission via liquid droplets in air.
Microscale liquid droplets could act as the SARS carriers in air when released from an infected person through breathing, coughing, or sneezing. In this study, a dynamic model has been built to quantitatively investigate the effect of the relative humidity on the transport of liquid-droplets in air using coupled mass transfer and momentum equations. Under higher relative humidity, the exhaled liquid droplets evaporate slowly. Larger droplets fall faster, which could reduce the probability of the droplets inhalation. This may be one of the most important factors that influence the SARS transmission in air.
Aerosols↗
Efficient disruption of a polyketide synthase gene ( pks1) required for melanin synthesis through Agrobacterium-mediated transformation of Glarea lozoyensis.
Glarea lozoyensis produces pneumocandin B(0), a potent inhibitor of fungal glucan synthesis. This industrially important filamentous fungus is slow-growing, is very darkly pigmented, and has not been easy to manipulate genetically. Using a PCR strategy to survey the G. lozoyensis genome for polyketide synthase (PKS) genes, we have identified pks1, a gene that consists of five exons interrupted by four introns of 56, 400, 50 and 341 bp. It encodes a 2124-amino acid protein with five catalytic modules: ketosynthase, acyltransferase, two acyl carrier sites, and thioesterase/Claisen cyclase. The transcriptional initiation and termination sites were found 43 bp upstream of the translational start codon and 295 bp downstream of the translational stop codon, respectively. Cluster analysis of 37 fungal ketosynthase modules grouped the Pks1p with PKSs involved in the biosynthesis of 1,8-dihydroxynaphthalene melanin. Disruption of pks1 yielded knockout mutants that displayed an albino phenotype, suggesting that pks1 encodes a tetrahydroxynaphthalene synthase. Gene replacement was achieved by Agrobacterium-mediated transformation, which proved to be simple and efficient. Loss of pigmentation occurred in more than half the transformants, and examination of six non-pigmented transformants showed that the functional genomic copy of the pks1 gene had been replaced by the disruption cassette in each case. A putative 1215-bp ORF (dsg) devoid of introns was present downstream from pks1. BLAST analysis of the 405-amino acid sequence of its predicted product showed a high degree of similarity with Zn(II)(2)Cys(6) binuclear cluster DNA-binding proteins, a class of fungal transcription factors involved in the regulation of polyketide production and other pathways.
Amino Acid Sequence↗
Determination of semivolatile compounds in drinking water by tandem mass spectrometric detection.
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China↗
Toxicity of chloroanilines and effects on superoxide dismutase activities in serum of crucian carp (Carassius auratus).
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Aniline Compounds↗
Kairomone strains of Euclytiaflava (Townsend), a parasitoid of stink bugs.
Tachinid flies commonly use the pheromones and allomones of stink bugs (Pentatomidae) as host-finding kairomones. Pheromone-baited traps for predaceous (Podisus spp.) and phytophagous (Euschistus spp.) pentatomids were used to obtain tachinid parasitoids in order to study the semiochemical relationships between these parasitic flies and their stink bug hosts. Gas chromatography-electroantennogram detector (GC-EAD) experiments and field tests were conducted to determine if pheromone strains of the tachinids, Euclytia flava and Hemyda aurata, occur in nature and to determine if the EAD-active compound, (E)-2-octenal (a common allomone compound of Heteroptera), affects attraction of tachinid parasitoids to synthetic Podisus pheromones. Addition of (E)-2-octenal to Podisus spp. synthetic pheromones in field traps tended to suppress attraction of the bugs, whereas (E)-2-octenal decreased, did not affect, or increased pheromonal attraction of tachinid parasitoids depending on the host species pheromone being tested and the habitat type in which the traps were deployed. Evidence from GC-EAD experiments of E. flava associated with different stink bug hosts suggested that kairomone-strains of this tachinid parasitoid coexist naturally. The significance of cryptic kairomone strains of parasitoids for classical biological control is discussed, and the mechanisms whereby parasitoids evolve kairomonally mediated host-shifts is considered.
Aldehydes↗
Comparison of different extraction techniques for the determination of polychlorinated organic compounds in sediment.
The performance of various enhanced extraction techniques, such as accelerated solvent extraction, microwave-assisted extraction, Soxhlet extraction, ultrasonic extraction and fluidized-bed extraction for the determination of polychlorinated organic compounds in dry sediment was investigated in two laboratories. The results of the two laboratories were in good agreement. The extraction yields from the batch extraction methods were lower than those from the dynamic techniques. Accelerated solvent extraction, especially, exhibited higher extraction efficiency than the standard procedure, Soxhlet extraction, whereas the results of fluidized-bed extraction were comparable.
Journal Article↗
Immature dendritic cells kill ovarian carcinoma cells by a FAS/FASL pathway, enabling them to sensitize tumor-specific CTLs.
Dendritic cells (DCs) can acquire antigen(s) from apoptotic tumor cells, resulting in an immunogen that can induce class I-restricted cytotoxic T lymphocytes (CTLs) and protective tumor rejection. Here, we investigated whether DCs derived from ascitic monocytes of patients with ovarian carcinoma could kill autologous ovarian tumor cells and if as a result they would acquire antigen(s) enabling them to induce a tumor-specific immunity. We found that the immature DCs could exert a significant cytotoxicity towards autologous and allogeneic ovarian tumor cells. This cytotoxicity was independent of Ca(2+) and could be inhibited by anti-Fas IgG1 monoclonal antibody, indicating the involvement of the Fas/Fas ligand (FasL) pathway in the cytotoxic mechanism. Further supporting this conclusion, the ascitic monocyte-derived DCs expressed high levels of FasL mRNA and intracellular FasL and significant levels of Fas were also revealed on the surface of ovarian tumor cells. Coculture of DCs induced apoptosis in ovarian carcinoma cells, as well as uptake of apoptotic tumor cells into the cytoplasma of the DCs, as visualized by immunofluoresence. Autologous DCs cocultured with apoptotic ovarian tumor cells were able to specifically stimulate tumor-specific CTLs, whereas DCs cocultured with necrotic ovarian cells were unable to do so. Collectively, these results demonstrate that immature DCs can kill autologous ovarian carcinoma cells via the Ca(2+)-independent Fas/FasL pathway and that this may have important consequences for their ability to stimulate tumor-specific CTLs.
Antibodies, Monoclonal↗
Construction of a mini-intein fusion system to allow both direct monitoring of soluble protein expression and rapid purification of target proteins.
Affinity purification of recombinant proteins has been facilitated by fusion to a modified protein splicing element (intein). The fusion protein expression can be further improved by fusion to a mini-intein, i.e. an intein that lacks an endonuclease domain. We synthesized three mini-inteins using overlapping oligonucleotides to incorporate Escherichia coli optimized codons and allow convenient insertion of an affinity tag between the intein (predicted) N- and C-terminal fragments. After examining the splicing and cleavage activities of the synthesized mini-inteins, we chose the mini-intein most efficient in thiol-induced N-terminal cleavage for constructing a novel intein fusion system. In this system, green fluorescent protein (GFP) was fused to the C-terminus of the affinity-tagged mini-intein whose N-terminus was fused to a target protein. The design of the system allowed easy monitoring of soluble fusion protein expression by following GFP fluorescence, and rapid purification of the target protein through the intein-mediated cleavage reaction. A total of 17 target proteins were tested in this intein-GFP fusion system. Our data demonstrated that the fluorescence of the induced cells could be used to measure soluble expression of the intein fusion proteins and efficient intein cleavage activity. The final yield of the target proteins exhibited a linear relationship with whole cell fluorescence. The intein-GFP system may provide a simple route for monitoring real time soluble protein expression, predicting final product yields, and screening the expression of a large number of recombinant proteins for rapid purification in high throughput applications.
Base Sequence↗
Phox homology domains specifically bind phosphatidylinositol phosphates.
The recruitment of specific cytosolic proteins to intracellular membranes through binding phosphorylated derivatives of phosphatidylinositol (PtdIns) controls such processes as endocytosis, regulated exocytosis, cytoskeletal organization, and cell signaling. Protein modules such as FVYE domains and PH domains that bind specifically to PtdIns 3-phosphate (PtdIns-3-P) and polyphosphoinositides, respectively, can direct such membrane targeting. Here we show that two representative Phox homology (PX) domains selectively bind to specific phosphatidylinositol phosphates. The PX domain of Vam7p selectively binds PtdIns-3-P, while the PX domain of the CPK PI-3 kinase selectively binds PtdIns-4,5-P(2). In contrast, the PX domain of Vps5p displays no binding to any PtdInsPs that were tested. In addition, the double mutant (Y42A/L48Q) of the PX domain of Vam7p, reported to cause vacuolar trafficking defects in yeast, has a dramatically decreased level of binding to PtdIns-3-P. These data reveal that the membrane targeting function of the Vam7p PX domain is based on its ability to associate with PtdIns-3-P, analogous to the function of FYVE domains.
Amino Acid Motifs↗
The use of an ultrafiltration technique for measurement of orthophosphate in shallow wetlands.
The overestimation of orthophosphate by filterable reactive phosphorus (FRP) measurement techniques has long been accepted. The aim of this study was to quantify that overestimation in 17 wetlands over time. Specifically an ultrafiltration technique was used prior to the application of the molybdenum blue phosphorus detection method to quantify orthophosphate concentrations. Samples were collected over a 6-month period and analysed for total filterable (< 0.50 microm) phosphorus (TFP), filterable reactive phosphorus (FRP < 0.50 microm) and ultrafiltered (< 10(3) Da) reactive phosphorus (PO4). FRP correlated well with PO4, however, FRP overestimated PO4 particularly with increasing colloidal phosphorus concentration. The ratio of DOC to TFP (C:P) influenced the fate of PO4 in the water, implying that DOC was forming complexes with phosphorus. The PO4 concentrations decreased with increasing C:P ratios in some of the wetlands over the 6-month monitoring period.
Colloids↗