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Y L Zhang

Publications and source records attributed to Y L Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Genotyping of human cystic echinococcosis in Xinjiang, PR China.

The Xinjiang Uygur Autonomous Region, multi-ethnic province in northwestern China, is one of the most important foci of human cystic echinococcosis (CE) in the world. Two Echinococcus granulosus genotypes (G1 and G6) are known to infect the intermediate hosts in this area but, to date, the source of the human infection remains unclear. The current study aimed to genetically analyse 67 hydatid cysts removed from 47 CE patients for which epidemiological, clinical and serological data were also recorded. Mitochondrial cox 1 gene sequencing suggested that the E. granulosus G1 genotype is the major source of infection (45/47 CE patients). Nevertheless, for the first time in China, 2 patients were found with hydatid cysts of the G6 genotype. In addition, 45 E. granulosus gravid tapeworms, isolated from 13 dogs, were genotyped. The majority of adult worms (42/45) exhibited the G1 genotype, whereas 3 adult tapeworms with the G6 genotype were found in one dog, that also harboured E. granulosus tapeworms of the G1 genotype. This sympatric occurrence of G1 and G6 genotypes of E. granulosus, not only in the same area but also in the same definitive host, raises the interesting question of putative genetic recombination between these E. granulosus genotypes.

Adolescent↗
PubMed2005

Bicyclic and tricyclic thiophenes as protein tyrosine phosphatase 1B inhibitors.

A novel pyridothiophene inhibitor of PTP1B was discovered by rational screening of phosphotyrosine mimics at high micromolar concentrations. The potency of this lead compound has been improved significantly by medicinal chemistry guided by X-ray crystallography and molecular modeling. Excellent consistency has been observed between structure-activity relationships and structural information from PTP1B-inhibitor complexes.

Crystallography, X-Ray↗
PubMed2005

Identification and characterization of putative virulence genes and gene clusters in Aeromonas hydrophila PPD134/91.

Aeromonas hydrophila is a gram-negative opportunistic pathogen of animals and humans. The pathogenesis of A. hydrophila is multifactorial. Genomic subtraction and markers of genomic islands (GIs) were used to identify putative virulence genes in A. hydrophila PPD134/91. Two rounds of genomic subtraction led to the identification of 22 unique DNA fragments encoding 19 putative virulence factors and seven new open reading frames, which are commonly present in the eight virulence strains examined. In addition, four GIs were found, including O-antigen, capsule, phage-associated, and type III secretion system (TTSS) gene clusters. These putative virulence genes and gene clusters were positioned on a physical map of A. hydrophila PPD134/91 to determine their genetic organization in this bacterium. Further in vivo study of insertion and deletion mutants showed that the TTSS may be one of the important virulence factors in A. hydrophila pathogenesis. Furthermore, deletions of multiple virulence factors such as S-layer, serine protease, and metalloprotease also increased the 50% lethal dose to the same level as the TTSS mutation (about 1 log) in a blue gourami infection model. This observation sheds light on the multifactorial and concerted nature of pathogenicity in A. hydrophila. The large number of putative virulence genes identified in this study will form the basis for further investigation of this emerging pathogen and help to develop effective vaccines, diagnostics, and novel therapeutics.

Aeromonas hydrophila↗
PubMed2003

Nitrate distribution and denitrification in the saturated zone of paddy field under rice/wheat rotation.

Nitrate concentration in well water collected from the wells near farm houses was investigated in the Taihu Lake basin (TBL) of China. Nitrate-N content of the well water ranged from 0.1 to 23 mgNl(-1), and 41% exceeded the criteria (10 mg Nl(-1)). It was found that the difference in well conditions, especially the depth of the well, was the main cause of the difference in the nitrate concentration of well water, i.e. it was higher in shallow well and lower in deeper well. A recommendation was made for local farmers to drill wells deeper than 10 m in order to reduce the risk of high ingestion of nitrate-N in their drinking water. Nitrate distribution and denitrification in the saturated zone of a paddy field under rice/wheat rotation in the TBL were studied. Porous pipes were installed in triplicate at depths of 1.5, 2.0, 2.5, 3.5 and 5 m respectively to collect the soil solution samples. Results showed that nitrate was the predominant N form in soil solution of saturated zone, and it increased from 1.5 to 2.5 m depth, and decreased from 2.5 to 5 m depth. N2O captured in the soil solution was very high comparing with N2O content in air. N2O content was positively correlated with nitrate concentrations in the soil profile. These results indicate that nitrate leached into saturated zone was mainly transformed via denitrification processes. Comparing the sum of inorganic nitrogen with the total nitrogen in soil solution samples collected from those wells at the field, some soluble organic nitrogen was found about 1-2 mg N l(-1) in average.

Biotransformation↗
PubMed2003

Detection and genetic analysis of group II capsules in Aeromonas hydrophila.

The genetic organization and sequences of the group II capsule gene cluster of Aeromonas hydrophila PPD134/91 have been determined previously. The purified capsular polysaccharides can increase the ability of avirulent strain PPD35/85 to survive in naive tilapia serum but have no inhibitory effect on the adhesion of PPD134/91 to carp epithelial cells. In this study, the presence of group II capsules among 33 randomly chosen A. hydrophila strains was examined by electron microscopy and genetic analysis. Ten strains were found to produce group II capsules. A PCR detection system was developed to identify two types of group II capsules (IIA and IIB) based on their genetic organization in the region II gene clusters. Group IIA capsules in the authors' collection of A. hydrophila strains are mainly found in the O : 18 and O : 34 serogroups, while group IIB capsules are found in the O : 21 and O : 27 serogroups. The presence of group II capsules in A. hydrophila strongly correlates with the serum and phagocyte survival abilities (seven out of ten strains). The results indicate that the authors' PCR detection system can constitute a reliable assay for the classification of group II capsules in A. hydrophila.

Aeromonas hydrophila↗
PubMed2002

Novel Aeromonas hydrophila PPD134/91 genes involved in O-antigen and capsule biosynthesis.

The sequences of the O-antigen and capsule gene clusters of the virulent Aeromonas hydrophila strain PPD134/91 were determined. The O-antigen gene cluster is 17,296 bp long and comprises 17 genes. Seven pathway genes for the synthesis of rhamnose and mannose, six transferase genes, one O unit flippase gene, and one O-antigen chain length determinant gene were identified by amino acid sequence similarity. PCR and Southern blot analysis were performed to survey the distribution of these 17 genes among 11 A. hydrophila strains of different serotypes. A. hydrophila PPD134/91 might belong to serotype O:18, as represented by JCM3980; it contained all the same O-antigen genes as JCM3980 (97 to 100% similarity at the DNA and amino acid levels). The capsule gene cluster of A. hydrophila PPD134/91 is 17,562 bp long and includes 13 genes, which were assembled into three distinct regions similar to those of the group II capsule gene cluster of Escherichia coli and other bacteria. Regions I and III contained four and two capsule transport genes, respectively. Region II had five genes which were highly similar to capsule synthesis pathway genes found in other bacteria. Both the purified O-antigen and capsular polysaccharides increased the ability of the avirulent A. hydrophila strain PPD35/85 to survive in naïve tilapia serum. However, the purified surface polysaccharides had no inhibitory effect on the adhesion of A. hydrophila PPD134/91 to carp epithelial cells.

Aeromonas hydrophila↗
PubMed2002

The vibration of an artery-like tube conveying pulsatile fluid flow.

A hybrid method for investigating pulsatile fluid flow in a long, thin, artery-like tube subjected to external excitations is presented. The non-linear partial differential equations governing the motion of the system, which incorporate the influence of circumferential strains, are solved by a combination of a finite element method, a finite difference method and a method of characteristics with interpolation. An initially axially stretched elastic tube conveying pulsating fluid, simply supported at both ends, is modelled to assess the effect of external harmonic excitation on the dynamic responses of the tube and the fluid flow. The results agree well with new experimental data. Comparison of the predicted results with those of a decoupled model demonstrates that it is necessary to consider the mechanism of fluid-structure interaction fully in the study of initially stretched cylindrical tubes conveying pulsatile fluid flow. An analysis of these coupling effects is presented for Womersley numbers alpha = 2.81 and 3.97 and a mean flow Reynolds number Re = 875.

Aorta↗
PubMed2001

Post-transcriptional stimulation of the assembly and secretion of triglyceride-rich apolipoprotein B lipoproteins in a mouse with selective deficiency of brown adipose tissue, obesity, and insulin resistance.

A mouse model of insulin resistance and its associated dyslipidemia was generated by crossing mice expressing human apolipoprotein B (apoB) with mice lacking only brown adipose tissue (BATless). On a high fat diet, male apoB/BATless mice became obese, hypercholesterolemic, hypertriglyceridemic, and hyperinsulinemic compared with control apoB mice. Fast performance liquid chromatography revealed increased triglyceride concentrations in intermediate density lipoprotein/low density lipoprotein (LDL) and reduced high density lipoprotein cholesterol concentrations. Inhibition of lipolysis by the drug, tetrahydrolipostatin, demonstrated that very low density lipoprotein-sized particles were initially secreted. Metabolic studies employing Triton WR-1339 and either [(3)H]glycerol or [(3)H]palmitate showed that the hypertriglyceridemia in apoB/BATless mice was due to the increased synthesis and secretion of triglyceride. Furthermore, lipoprotein lipase and hepatic lipase activities were not defective. ApoB was also secreted at increased rates in the apoB/BATless mice. Similar levels of apoB mRNA in apoB and apoB/BATless mice indicated that apoB secretion was regulated post-transcriptionally. LDL receptor mRNA was increased in the apoB/BATless mice, indicating that the observed increase in apoB-lipoprotein secretion was not due to their decreased reuptake. Finally, mRNA levels of the large subunit of microsomal triglyceride transfer protein, a required component for very low density protein assembly, were not different between apoB and apoB/BATless mice. This rodent model should prove useful in exploring mechanisms underlying the regulation of apoB secretion in the context of insulin resistance.

Adipose Tissue, Brown↗
PubMed2001

An antimicrobial peptide gene found in the male reproductive system of rats.

Little is known about the innate defense mechanisms of the male reproductive tract. We cloned a 385-base pair complementary DNA and its genomic DNA named Bin1b that is exclusively expressed in the caput region of the rat epididymis and that is responsible for sperm maturation, storage, and protection. Bin1b exhibits structural characteristics and antimicrobial activity similar to that of cationic antimicrobial peptides, beta-defensins. Bin1b is maximally expressed when the rats are sexually mature and can be up-regulated by inflammation. Bin1b appears to be a natural epididymis-specific antimicrobial peptide that plays a role in reproductive tract host defense and male fertility.

Animals↗
PubMed2001

The in vitro activity of sulbactam combined with third generation cephalosporins against third generation cephalosporin-resistant bacteria.

The in vitro activity of the beta-lactamase inhibitor sulbactam combined with cefuroxime, cefotaxime or ceftazidime in the ratio of 1:1 was studied against ceftazidime- or cefuroxime-resistant Gram-negative rods and Staphylococcus aureus. Sulbactam enhanced the antibacterial activities of cefuroxime, cefotaxime and ceftazidime against Gram-negative rods. The MIC(90) of ceftazidime against Escherichia coli, Enterobacter cloacae, Citrobacter freundii, Acinetobacter spp. and Pseudomonas aeruginosa was reduced 4-fold and that of cefotaxime against E. coli, E. cloacae, C. freundii and Acinetobacter spp. reduced by 2-4-fold. However, sulbactam did not enhance the activities of cefuroxime, cefotaxime or ceftazidime against S. aureus, enterococci and Stenotrophomonas maltophilia. With the combination of sulbactam and ceftazidime at the ratio of 1:1, 38.4% of E. coli, 45.3% of E. cloacae, 66.6% of C. freundii and 60% of Acinetobacter spp. initially resistant to ceftazidime became susceptible.

Cephalosporin Resistance↗
PubMed2001

Detection of amp C in Enterobacter cloacae in China.

PCR amplification of 55 strains of Enterobacter cloacae indicated 51 of them had amp C structural gene verified by DNA sequence and Southern blotting. All PCR products were cleaved into 666- and 328-bp fragments by Kpn1 restriction enzyme. Imipenem was the most potent inducer for mRNA expression of amp C gene and beta-lactamase activity. The beta-Lactamase inhibitor R0481220 strongly inhibited Amp C beta-lactamases; 96.4% (53/55) of Enterobacter cloacae producing Amp C enzyme were susceptible to cefepime.

Bacterial Proteins↗
PubMed2001

Laser confocal microscopic study of pH profiles of synthetic absorbable fibers upon in vitro hydrolytic degradation.

The objective of this study was to develop a new and non-destructive technique to measure the interior pH of synthetic absorbable biomaterials. Such a measurement would provide the required experimental evidence for validating the postulated theory that the accumulation of acidic hydrolytic degradation products within the interior of aliphatic polyesters is responsible for the observed accelerated degradation of this class of absorbable biomaterials. This new technique used a laser scanning confocal microscope coupled with pH sensitive fluorescent dyes like Texas Red sulfonyl chloride. The capability of optical thin sectioning of a laser confocal microscope would permit a non-destructive examination of the interior of biomaterials. Poly-p-dioxanone suture fibers (PDSII) of size 2/0 were used as the model compound for this new technique. The pH values of the unhydrolyzed and partially hydrolyzed PDSII fibers were found to decrease with increasing depth from the fiber surface and reached as low as about 3.5 at 70 microm depth. The largest depth that an interior pH could be measured within absorbable biomaterials was determined by the opacity of the biomaterials, i.e. a higher depth for a less opaque material. The observed interior pH profiles were correlated to the unique morphologic structure of PDSII fibers.

Journal Article↗
PubMed2001

Primate epididymis-specific proteins: characterization of ESC42, a novel protein containing a trefoil-like motif in monkey and human.

Epididymal secreted proteins promote sperm maturation and fertilizing capacity by interacting with sperm during passage through the epididymis. Here we investigate the molecular basis of sperm maturation by isolating cDNA clones for novel epididymis-specific expressed sequences. Thirty-six novel cDNAs were isolated and sequenced from a subtracted Macaca mulatta epididymis library. The clones encode proteins with a range of motifs characteristic of protein-modifying enzymes, protease inhibitors, hydrophobic ligand-binding and transport proteins, extracellular matrix-interacting proteins, and transcription regulatory factors. The full length coding sequences were obtained for 11 clones representing a range of abundance levels. Expression of each is regionally localized and androgen regulated. The most abundant, ESC42, contains a cysteine-rich region similar to the signature binding domain of the trefoil family of motogenic wound repair proteins. The monkey and human proteins are nearly 90% identical. Immunohistochemical staining revealed that the protein is most abundant in the epithelium of the caput and is also present in the lumen and bound to sperm. The ESC42 gene, located on chromosome 20q11, contains two exons encoding two nearly identical predicted signal peptides and a third exon encoding the rest of the protein.

Amino Acid Sequence↗
PubMed2001

Construction and selection of the natural immune Fab antibody phage display library from patients with colorectal cancer.

AIM: To construct the natural immune Fab antibody phage display libraries of colorectal cancer and to select antibodies related with colorectal cancer. METHODS: Extract total RNA from tissue of local cancer metastasis lymph nodes of patients with colorectal cancer. RT-PCR was used to amplify the heavy chain Fd and light chain kappa and the amplification products were inserted successively into the vector pComb3 to construct the human libraries of Fab antibodies. They were then panned by phage display technology. By means of Dot immunoblotting and ELISA, the libraries were identified and the Fab phage antibodies binding with antigens of colorectal cancer were selected. RESULTS: The amplified fragments of Fd and kappa gained by RT-PCR were about 650 bp. Fd and kappa PCR products were subsequently inserted into the vector pComb3, resulting in a recombination rate of 40% and the volume of Fab phage display library reached 1.48 x 10(6). The libraries were enriched about 120-fold by 3 cycles of adsorption-elution-multiplication (panning). Dot immunoblotting showed Fab expressions on the phage libraries and ELISA showed 5 clones of Fab phage antibodies which had binding activities with antigens of colorectal cancer. CONCLUSION: The natural immune Fab antibody phage display libraries of colorectal cancer were constructed. They could be used to select the relative antibodies of colorectal cancer.

Antibodies↗
PubMed2001

[Experimental study of allogenic tendon with sheath grafting in chicken].

OBJECTIVE: To investigate availability of deep freeze stored allogenic tendon with sheath grafting in repairing the tendon and sheath defect in the II area of flexor digitorum tendon. METHODS: Sixty chickens with tendon and sheath defect were divided into 2 groups randomly, group A was treated with allogenic grafting and group B was treated with autogenic grafting, these two groups were divided into two subgroups respectively, they were, group A1 allogenic tendon with whole sheath grafting, group A2 allogenic tendon with partial sheath grafting, group B1 autogenic tendon with whole sheath grafting and group B2 autogenic tendon with whole sheath grafting. All the allogenic grafts were treated by deep freeze. Histomorphological study, histoimmunological study and slipping function of the grafts were measured after operation. RESULTS: In group A1 and B1, the local reaction was sever, the nutrition of tendon graft was barricaded by the whole sheath resulting in adhesion, degeneration and necrosis. In group A2 and B2, the tendon graft healed well and little adhesion existed between tendon and sheath. The results showed that there were significant differences between tendon grafting with whole sheath and tendon grafting with partial sheath. CONCLUSION: Deep freeze store can reduce the immunogenicity of allogenic tendon with sheath. Allogenic tendon with partial sheath grafting can be used as a new biological material for repairing the tendon and sheath defect.

Animals↗
PubMed2001

Effects of melittin on isolated papillary muscles of guinea pig.

AIM: To investigate the effect of melittin (Mel) on papillary muscles of guinea pigs. METHODS: Contraction of papillary muscles were examined by conventional method and action potentials (AP) were recorded by standard glass microelectrode technique. RESULTS: Mel (0.5, 3 micromol/L) significantly increased the contractility of guinea pig papillary muscles while 5 micromol/L exerted dual action with a transient decrease followed by an increase of the contractility. Mel shortened the functional refractory period (FRP) at concentrations of 0.5, 3, and 5 micromol/L and increased the automaticity induced by adrenaline (Adr) at 3 and 5 micromol/L. Mel shifted the duration-intensity curve upward at 3 micromol/L. It shortened the action potential duration (APD) of fast action potential (FAP), decreased the action potential amplitude (APA) and resting potential (RP) at 0.5 and 3 micromol/L. As to slow action potential (SAP), Mel 0.8 micromol/L shortened APD20 and APD50, and decreased APA and RP. CONCLUSION: Mel increased the contractility and automaticity of papillary muscles, shortened the FRP, decreased the excitability, shortened the APD, and decreased APA and RP of AP.

Action Potentials↗
PubMed2001

Successful production of offspring after superovulation and in vitro culture of embryos from domestic ferrets (Mustela putorius furos).

In an effort to expand the use of ferrets as models for genetic disease, several experimental parameters that are required for successful genetic manipulation in this species were investigated. Optimum superovulation (19.3 +/- 0.6 oocytes and embryos per female) was achieved after injections of 100 iu equine chorionic gonadotrophin (eCG) and 150 iu human chorionic gonadotrophin (hCG). The ovulation rate achieved by the treatment was more than double that induced by mating. Mating with a male immediately after hCG treatment did not significantly alter the number of oocytes ovulated or the number of embryos present, indicating that mating is not required for superovulation in ferrets. Of embryos harvested at the one-cell stage, 64.5% and 47.1% developed into blastocysts when cultured in vitro in CZB or TCM-199 plus 10% fetal bovine serum (FBS) media, respectively. In contrast, only 17.1% of embryos cultured in vitro in NCSU-23 developed to the blastocyst stage. Both freshly retrieved and in vitro cultured embryos from cinnamon-coloured parents produced live young when transferred at the eight-cell stage into albino, pseudo-pregnant recipients. The percentage of kits delivered relative to embryos transferred was 61% for freshly retrieved embryos and 32% for embryos cultured in vitro. These results demonstrate successful embryo transfer in ferrets and provide a basis for further study of genetic modelling approaches in this species after embryo manipulation.

Analysis of Variance↗