Biomedical subjects

W Xiang

Publications and source records attributed to W Xiang.

At least 19 recordsLinked to original sources

PubMed2006

Significant association of a M129V independent polymorphism in the 5' UTR of the PRNP gene with sporadic Creutzfeldt-Jakob disease in a large German case-control study.

BACKGROUND: A single nucleotide polymorphism (SNP) in the coding region of the prion protein gene (PRNP) at codon 129 has been repeatedly shown to be an associated factor to sporadic Creutzfeldt-Jakob disease (sCJD), but additional major predisposing DNA variants for sCJD are still unknown. Several previous studies focused on the characterisation of polymorphisms in PRNP and the prion-like doppel gene (PRND), generating contradictory results on relatively small sample sets. Thus, extensive studies are required for validation of the polymorphisms in PRNP and PRND. METHODS: We evaluated a set of nine SNPs of PRNP and one SNP of PRND in 593 German sCJD patients and 748 German healthy controls. Genotyping was performed using MALDI-TOF mass spectrometry. RESULTS: In addition to PRNP 129, we detected a significant association between sCJD and allele frequencies of six further PRNP SNPs. No significant association of PRND T174M with sCJD was shown. We observed strong linkage disequilibrium within eight adjacent PRNP SNPs, including PRNP 129. However, the association of sCJD with PRNP 1368 and PRNP 34296 appeared to be independent on the genotype of PRNP 129. We additionally identified the most common haplotypes of PRNP to be over-represented or under-represented in our cohort of patients with sCJD. CONCLUSION: Our study evaluated previous findings of the association of SNPs in the PRNP and PRND genes in the largest cohorts for association study in sCJD to date, and extends previous findings by defining for the first time the haplotypes associated with sCJD in a large population of the German CJD surveillance study.

5' Untranslated Regions↗

PubMed2005

Expression of endothelial nitric oxide synthase traffic inducer in the placentas of women with pre-eclampsia.

OBJECTIVE: To investigate the expression of endothelial nitric oxide synthase traffic inducer (NOSTRIN) in the placenta of women with pre-eclampsia (PE) and discuss its role in the pathogenesis of PE. METHODS: Western blot analysis was used to detect the expression of NOSTRIN and endothelial nitric oxide synthase (eNOS). The activity of eNOS in placental tissue was assayed by spectrophotometry. Serum and placental NO(2)/NO(3), the stable metabolic end product of NO, was measured using nitrate reductase. RESULTS: Western blot analysis showed that the protein level of NOSTRIN was significantly higher in women with PE than in the control group (P<0.01). However, no significant difference between groups was observed in the expression of placental eNOS (P>0.05). The activity of eNOS was significantly decreased in women with PE (13.727+/-3.58 U/mg) compared with the control group (21.69+/-3.84 U/mg) (P<0.01). The placental levels of NO(2)/NO(3) were significantly lower in women with PE (27.53+/-8.51 micromol/mg) than in the control group (44.38+/-9.59 micromol/mg) (P<0.01). The levels of serum NO(2)/NO(3) were significantly lower in women with PE (48.56+/-8.49 micromol/L) than in the control group (65.37+/-9.61 micromol/L) (P<0.01). A significant negative correlation existed between the expression of NOSTRIN protein and the activity of eNOS in the placental tissues of women with PE (r=-0.57, P<0.01). CONCLUSION: The level of NOSTRIN expression in the placental tissues of women with PE is increased and is negatively correlated with the activity of eNOS-which may play an important role in the pathogenesis of PE.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Prion protein codon 129 polymorphism and risk of Alzheimer disease.

The authors investigated the PRNP Met129Val polymorphism in 1,393 subjects including 482 patients with Alzheimer disease (AD) and two independent control groups. In patients, PRNP Met homozygosity conferred increasing risk with decreasing age at onset (onset: 61 to 70 years, n = 151, p = 0.02, odds ratio [OR] = 1.72, 95% CI = 1.2 to 2.53; onset: < or =60 years, n = 138, p = 0.013, OR = 1.92, 95% CI = 1.31 to 2.87), whereas no association was obtained in patients with onset at older than 70 years. The results suggest involvement of the prion protein in the pathogenesis of early-onset AD.

Age of Onset↗

PubMed2001

Photodynamic effects induced by aminolevulinic acid esters on human cervical carcinoma cells in culture.

Fluorescence diagnosis and photodynamic therapy using 5-aminolevulinic acid (ALA) provide new methods for the detection and treatment of cervical cancer and especially its precursors. However, these techniques are restricted by the rate of uptake of the hydrophilic ALA, its poor diffusion through the bilayer of biological membranes or both. In this study we evaluated the effect of some esterified ALA derivatives on the induction of the endogenous photosensitizer, protoporphyrin IX (PpIX), and the photodamage in cultured human cervical cells (C33-A and CaSki). The kinetics of PpIX accumulation showed that ALA esters, especially the ALA-hexylester (h-ALA), induced significantly faster PpIX formation than ALA at the same concentration (0.5 mM). The PpIX induction showed a dose-dependent characteristic. The highest PpIX values could be achieved by an up to 1.3-13-fold lower concentration of ALA esters than with ALA. Using the Annexin V assay, apoptosis was found to be induced rapidly after irradiation in both ALA- and ALA esters-treated cells. On measuring mitochondrial activity, the incubation with h-ALA induced a more pronounced photodamage. The results indicate that improved or at least comparable photodynamic effects can be achieved by using remarkably lower doses of ALA esters.

Aminolevulinic Acid↗

PubMed2001

[Soil and water loss from cultivated slope land derived from granite under different cropping systems in Three-Gorges reservoir areas].

The water and soil loss caused by cultivation on slope land derived from granite under different cropping systems in the Three-Gorges reservoir area was analyzed based on the data from localized observation. The results showed that in this area, proximately 60% of total annual rainfall, distributed in May to August, and 60% of soil erosion occurred in these four months, with 50% in June and July. The coverage rates under different cropping systems differed significantly, e.g., triple-cropping systems and inter-croping system with perennial plants (grass and day lily) had a bigger covering than double-cropping systems. The soil loss under cropping system with peanut was much lower than that with sweet potato, because the covering rate of the former was higher than that of the latter in summer raining season. The sequence of soil and nutrient loss for different cropping systems was rape (wheat) sweet potato > rape(wheat)/corn/sweet potato > rape(wheat)/corn/peanut/rape(wheat)/grass/peanut/rape(wheat)/day lily/peanut. It was concluded that soil loss from cultivated slope land could be controlled below a permissible value, if rational cropping and management systems were adopted.

Agriculture↗

PubMed2000

The primate lentiviral receptor Bonzo/STRL33 is coordinately regulated with CCR5 and its expression pattern is conserved between human and mouse.

Chemokines play necessary and important roles in regulating the trafficking of lymphocytes to intra- or interlymphoid tissues as well as to sites of inflammation. The complex migratory patterns of lymphoid lineage cells is governed by subset-specific expression of chemokine receptors and their access to specific ligands. Several chemokine receptors and chemokine receptor-like orphan receptors also serve, in conjunction with CD4, as coreceptors for infection by human and simian immunodeficiency viruses (HIV and SIV). Here we show that the expression pattern of Bonzo/STRL33, an orphan SIV/HIV coreceptor, is highly restricted to the memory subset of T cells and is up-regulated upon stimulation of these cells with IL-2 or IL-15. Both the pattern and the regulation of Bonzo expression closely paralleled that of CC family chemokine receptors CCR5 or CCR6 and inversely correlated with CXCR4 expression. However, in striking contrast to CCR5, Bonzo expression was not down-modulated by PMA or mitogen stimulation of T cells. Targeted replacement of the Bonzo gene with a gene encoding green fluorescent protein in mice revealed that the expression and cytokine regulation of mouse Bonzo are comparable to those of its human counterpart. The similar expression and regulation patterns of Bonzo and the HIV coreceptor CCR5 may have implications for understanding the role of HIV/SIV receptors in viral evolution and pathogenesis.

Animals↗

PubMed2000

Photodetection of cervical intraepithelial neoplasia using 5-aminolevulinic acid-induced porphyrin fluorescence.

BACKGROUND: Screening for cervical carcinoma and its precursors is based on cervical cytology and diagnostic colposcopy. Despite the decrease in the incidence of cervical carcinoma in countries with a good screening program, this rate of decline is leveling off. Known problems are false-negative rates of cytology and low specificity of colposcopy. This clinical study examined the diagnostic potential of porphyrin fluorescence in patients with cervical intraepithelial neoplasia Grade 1-3 (CIN 1-3). METHODS: Sixty-eight women attending our colposcopy clinic underwent a gynecologic examination, including cytology, human papillomavirus (HPV) testing, and colposcopy. They received 10 mL 0.5% or 1.0% 5-aminolevulinic acid (5-ALA) topically. After 30-360 minutes, real-time image analysis was performed, and spectra were obtained from 685 sites. RESULTS: Due to rapid photobleaching, 0.5% 5-ALA proved ineffective for fluorescence assessment. Using 1% 5-ALA, the authors found that fluorescence intensities correlated with incubation time; however, fluorescence contrast showed a maximum at 60-90 minutes (ratio 11:1). HPV DNA positive lesions showed significantly higher fluorescence. Fluorescence imaging after 60-90 minutes achieved similar sensitivity and specificity compared with colposcopy in detecting CIN with 94% and 51% versus 95% and 50%, respectively. However, the specificity was markedly improved by fluorescence spectroscopy, achieving 75%. The evaluation of spectral measurements revealed significantly higher values for CIN compared with normal tissue and for CIN 2/3 compared with CIN 1 (P < 0.001). CONCLUSIONS: Using a time interval of 60-90 minutes after topical application of 1% 5-ALA, the authors observed specific porphyrin fluorescence of CIN. Fluorescence spectroscopy promises to become a valuable tool for the diagnosis of CIN.

Adult↗

PubMed2000

Assessment of 5-aminolevulinic acid-induced porphyrin fluorescence in patients with peritoneal endometriosis.

OBJECTIVE: The purpose of this study was to examine the diagnostic potential for patients with endometriosis of porphyrin fluorescence after oral administration of 5-aminolevulinic acid. STUDY DESIGN: Fifteen women referred for laparoscopy because of suspected endometriosis received 1 or 10 mg/kg 5-aminolevulinic acid orally. After 1.5 to 6 hours endoscopic fluorescence spectral analysis and video inspection were performed. RESULTS: With 10 mg/kg 5-aminolevulinic acid and application intervals of >3 hours we observed a significantly higher porphyrin fluorescence in active peritoneal endometriosis than in adjacent normal peritoneum. Pigmented and nodular endometriosis showed weak to negative fluorescence. A strong fluorescence of the fimbrial mucosa was seen. A 1-mg/kg dose of 5-aminolevulinic acid was insufficient for fluorescence diagnosis. No side effects were recorded. CONCLUSION: Porphyrin fluorescence after oral administration of 5-aminolevulinic acid may be beneficial in diagnosis of peritoneal endometriosis. The strong fluorescence of fimbrial mucosa may limit the applicability of this technique in young women, however, because phototoxic damage cannot be excluded at present.

Adult↗

PubMed1999

Identification of seven serotypes of bluetongue virus from the People's Republic of China.

Seven serotypes (1, 2, 3, 4, 12, 15 and 16) of bluetongue virus were isolated from the blood of sheep and cattle in the People's Republic of China between 1986 and 1996. Six of these viruses were isolated in Yunnan province. The sheep from which serotypes 1 and 16 were isolated showed obvious signs of bluetongue disease, whereas the cattle from which serotypes 2, 3, 4, 12 and 15 were isolated were clinically normal. Phylogenetic analyses of these viruses indicate that they are more closely related to one another, and to an Australian strain of serotype 1, than they are to prototype strains of bluetongue virus serotypes 2, 10, 11, 13 and 17 from the USA.

Animals↗

PubMed1999

Changes in cell morphology and actin organization during heat shock in Dictyostelium discoideum: does HSP70 play a role in acquired thermotolerance?

In response to heat shock (34 degrees C, 30 min), cell morphology and actin organization in Dictyostelium discoideum are drastically changed. Loss of pseudopodia and disappearance of F-actin-containing structures were observed by using fluorescence microscopy. These changes were paralleled by a rapid decrease of the F-actin content measured by a TRITC-phalloidin binding assay. The effects of heat shock on cell morphology and actin organization are transient: After heat shock (34 degrees C) or during a long-term heat treatment (30 degrees C), cell morphology, F-actin patterns and F-actin content recovered/adapted to a state which is characteristic for untreated cells. Because F-actin may be stabilized by increased amounts of heat shock proteins, their response and interaction with F-actin was analyzed. After a 1 h heat treatment (34 degrees C), the major heat shock protein of D. discoideum (HSP70) showed maximally increased synthesis rates and levels. During recovery from a 34 degrees C shock or during a continuous heat treatment at 30 degrees C, the HSP70 content first increased and then declined slowly toward normal levels. Pre-treatment of cells with a short heat shock of 30 min at 34 degrees C stabilized the F-actin content when the cells were exposed to a second heat shock. Furthermore, a transient colocalization of HSP70 and actin was observed at the beginning of heat treatment (30 degrees C) using immunological detection of HSP70 in the cytoskeletal actin fraction.

Actins↗

PubMed1999

Sequence comparison of the L2 and S10 genes of bluetongue viruses from the United States and the People's Republic of China.

Bluetongue virus (BTV) infection of ruminants is endemic throughout much of the US and China. The S10 and a portion of the L2 gene segments of Chinese prototype strains of BTV serotypes 1, 2, 3, 4, 12, 15, and 16 were sequenced and compared to the same genes of prototype and field strains of BTV from the US. Phylogenetic analysis of the S10 gene segregated the Chinese viruses into a monophyletic group distinct from the US viruses, whereas similar analysis of the L2 gene segregated strains of BTV according to serotype, regardless of geographic origin.

Bluetongue virus↗

PubMed1999

[Apolipoprotein E polymorphism and plasma lipid, lipoprotein, apolipoprotein levels in 291 children of Changsha].

In order to investigate the distribution of apolipoprotein (Apo) E polymorphism and effect of ApoE genotypes on plasma lipid, lipoprotein, apolipoprotein levels in children of Changsha, we determined ApoE genotypes in 291 children by means of PCR-RFLP. ApoE allele frequencies in the population were epsilon 2 = 0.081, epsilon 3 = 0.857, epsilon 4 = 0.062. There were no difference in the ApoE genotypes distribution between sexes. The children with Apo epsilon 2 allele had higher levels of ApoE, ApoA1 and high density lipoprotein-cholesterol together with lower levels of total cholesterol, ApoB100 and low density lipoprotein-cholesterol than those with other ApoE alleles. These changes were opposite in children with Apo epsilon 4 allele. The levels of plasma triglyceride, lipoprotein(a) were not affected significantly by ApoE alleles. Moreover, the effect of ApoE genotypes on levels of plasma lipids was different between sexes. These results suggest that ApoE polymorphisms could affect plasma lipids metabolism in children.

Adolescent↗

PubMed1998

A protein linkage map of the P2 nonstructural proteins of poliovirus.

The yeast two-hybrid system was used to catalog all detectable interactions among the P2 nonstructural cleavage products of poliovirus type 1 (Mahoney). Evidence has been obtained for specific associations among 2A(pro), 2BC, 2C, and 2B. Specifically, 2A(pro) can interact with itself and 2BC and its cleavage products (2B and 2C) interact in all possible combinations, with the exception of 2C/2C. Detected interactions were confirmed in vitro by a glutathione S-transferase pulldown assay, which allowed us to detect 2C/2C association. transdominant-negative mutants of 2B (K. Johnson and P. J. Sarnow, J. Virol. 65:4341-4349, 1991) were examined and were found to retain interaction with wild-type 2B, perhaps reflecting a need for 2B multimerization in viral RNA replication. The multimerization of 2B was examined further by screening a mutagenized library for 2B variants that have lost the ability to bind wild-type 2B. The screen identified two nonconservative missense mutations within a central hydrophobic region, as well as truncations and frameshifts that implicate the C terminus in homointeraction. Introduction of the missense mutations into the genome of the virus conferred a quasi-infectious phenotype, an observation strongly suggesting that the 2B/2B interaction is required for replication of the viral genome.

Carrier Proteins↗

PubMed1998

Complete protein linkage map of poliovirus P3 proteins: interaction of polymerase 3Dpol with VPg and with genetic variants of 3AB.

Poliovirus has evolved to maximize its genomic information by producing multifunctional viral proteins. The P3 nonstructural proteins harbor various activities when paired with different binding partners. These viral polypeptides regulate host cell macromolecular synthesis and function as proteinases, as RNA binding proteins, or as RNA-dependent RNA polymerase. A cleavage product of the P3 region is the genome-linked protein VPg that is essential in the initiation of RNA synthesis. We have used an inducible yeast two-hybrid system to analyze directly protein-protein interactions among P3 proteins. Sixteen signals of homo- or heterodimer interactions have been observed and have been divided into three groups. Of interest is the newly discovered affinity of VPg to 3Dpol that suggests direct interaction between these molecules in genome replication. A battery of 3AB variants (eight clustered-charge-to-alanine changes and five single-amino-acid mutations) has been used to map the binding determinants of 3AB-3AB interaction which were found to differ from the amino acids critical for the 3AB-3Dpol interaction. The viral proteinase 3Cpro was not found to interact with other 3Cpro molecules or with any other P3 polypeptide in yeast cells, a result confirmed by glutaraldehyde cross-linking. The weak apparent interaction between 3AB and 3CDpro scored in the yeast two-hybrid system was in contrast to a strong signal by far-Western blotting. The results elucidate, in part, previous results of biochemical and genetic analyses. The role of the interactions in RNA replication is addressed.

Amino Acid Sequence↗

PubMed1998

[Degradation of phytic acid in rapeseed meal by two strains of molds].

By using selective media, two strains of molds which are able to degrade phytic acid were isolated from soil samples. These molds are able to use inositol as the sole carbon and energy sources for growth. In broth cultures, the degradation rates of phytic acid by these molds were 74.4% and 95.0%, respectively. However, in solid-state fermentation which used rapeseed meal as a raw material, the degradation rate was about 40%. Several metal ions tested were able to enhance the degradation rate of phytic acid. Factors such as temperature, pH and moisture content which affect the growth of molds were also explored. These two strains of molds were initially identified as Paecilomyces sp. and Penicillium sp.. They do not produce any detectable amount of aflatoxins.

Biodegradation, Environmental↗

PubMed1997

Identifying and recruiting healthy control subjects from a managed care organization: a methodology for molecular epidemiological case-control studies of cancer.

Case-control studies with stringent matching criteria require large pools of healthy subjects from which to select matched controls. This paper describes a successful method of identifying a large pool of potential control subjects to participate in two molecular epidemiological case-control studies of lung cancer, each enrolling 400 case subjects and 400 control subjects. These studies are not population based, and the study base is not well-defined. Therefore, potential control subjects are being identified and recruited through 20 area clinic sites of a large multispecialty health maintenance organization. Because the research focus is driven by genetic hypotheses and we are controlling for multiple smoking-related variables, representativeness is of lesser concern. To identify potential control subjects, a one-page questionnaire is distributed to patients in the waiting room to assess contact information as well as data relevant to the case-control matching process. An average of 2,228 questionnaires are returned monthly toward a target pool of 40,000; of these, 59% of the respondents fulfill eligibility criteria as a control subject for one of the studies and are not averse to being contacted in the future for the purpose of research. When compared to former smokers and never smokers, current smokers in the control population were least likely to refuse further contact. A collaborative arrangement with a managed care organization offers a feasible mechanism through which researchers can access a large, ethnically diverse population of potential control subjects.

Adolescent↗

PubMed1995

Interaction between the 5'-terminal cloverleaf and 3AB/3CDpro of poliovirus is essential for RNA replication.

On the basis of sequence alignments and secondary structure comparisons of the first 100 nucleotides of enterovirus and rhinovirus RNAs, chimeric constructs in which this region of poliovirus type 1 Mahoney [PV1(M)] is replaced with that of human rhinovirus type 2 (HRV2) or HRV14 have been engineered. These chimeric constructs contain the internal ribosomal entry site of either poliovirus or encephalomyocarditis virus. Independent of the internal ribosomal entry site elements, only the constructs containing either the PV1(M) or HRV2 cloverleaf sequences yielded viable viruses. The secondary structures of all three cloverleaves are quite similar. However, highly purified polioviral proteins 3CDpro and 3AB together bound to the PV1(M) and HRV2 cloverleaves, albeit with different affinities, whereas the HRV14 homolog did not interact with these proteins to any appreciable extent. These results support a mechanism of poliovirus genomic replication in which the formation of a complex between the cloverleaf structure and the 3CDpro/3AB proteins of poliovirus plays an essential role.

3C Viral Proteases↗

PubMed1995

Molecular dissection of the multifunctional poliovirus RNA-binding protein 3AB.

Genome replication of poliovirus, as yet unsolved, involves numerous viral polypeptides that arise from proteolysis of the viral polyprotein. One of these proteins is 3AB, an RNA-binding protein with multiple functions, that serves also as the precursor for the genome-linked protein VPg (= 3B). Eight clustered charged amino acid-to-alanine mutants in the 3AB coding region of poliovirus were constructed and analyzed, together with three additional single-amino acid exchange mutants in VPg, for viral phenotypes. All mutants expressed severe inhibition in RNA synthesis, but none were temperature sensitive (ts). The 3AB polypeptides of mutants with a lethal phenotype were overexpressed in Escherichia coli, purified to near homogeneity, and studied with respect to four functions: (1) ribonucleoprotein complex formation with 3CDpro and the 5'-terminal cloverleaf of the poliovirus genome; (2) binding to the genomic and negative-sense RNA; (3) stimulation of 3CDpro cleavage; and (4) stimulation of RNA polymerase activity of 3Dpol. The results have allowed mapping of domains important for RNA binding and the formation of certain protein-protein complexes, and correlation of these processes with essential steps in viral genome replication.

3C Viral Proteases↗