Biomedical subjects

X Tao

Publications and source records attributed to X Tao.

At least 19 recordsLinked to original sources

PubMed2001

Arterial remodeling in chronic sinoaortic-denervated rats.

The spontaneous variation of blood pressure is defined as "blood pressure variability" (BPV). The chronic sinoaortic-denervated (SAD) rat is a model of high BPV without sustained hypertension. Little is known about vascular remodeling in this model. In the present study, we examined blood pressure, vascular remodeling, and aortic angiotensin II concentration in chronic SAD rats in separate experiments. In experiment 1, intra-arterial blood pressure was continuously recorded in conscious unrestrained rats. The 16-week SAD rats had a significant increase in BPV and no change in the mean level of blood pressure over a 24-h period. In experiment 2, we measured structural changes of seven kinds of arteries by histologic method and computer image analysis and functional changes of thoracic aortas by isolated artery preparation. Structural remodeling after 16-week sinoaortic denervation was characterized by increase in wall thickness, wall area, and ratio of wall thickness to internal diameter, with different changes in internal diameter and external diameter in different arteries, indicating that arterial structural remodeling expresses itself mainly as vascular growth. This vascular growth might be caused by medial smooth muscle cell growth and collagen accumulation. Aortic contraction induced by norepinephrine was potentiated, whereas aortic relaxation induced by acetylcholine was attenuated after sinoaortic denervation. In experiment 3, plasma and aortic angiotensin II concentrations were determined by radioimmunoassay. The former remained unchanged, whereas the latter was significantly increased in 10-week SAD rats. It is concluded that in rats chronic sinoaortic denervation can produce vascular remodeling that might be related to increased BPV and an activated tissue renin-angiotensin system.

Angiotensin II↗

PubMed2000

Structural basis for signal transduction by the Toll/interleukin-1 receptor domains.

Toll-like receptors (TLRs) and the interleukin-1 receptor superfamily (IL-1Rs) are integral to both innate and adaptive immunity for host defence. These receptors share a conserved cytoplasmic domain, known as the TIR domain. A single-point mutation in the TIR domain of murine TLR4 (Pro712His, the Lps(d) mutation) abolishes the host immune response to lipopolysaccharide (LPS), and mutation of the equivalent residue in TLR2, Pro681His, disrupts signal transduction in response to stimulation by yeast and gram-positive bacteria. Here we report the crystal structures of the TIR domains of human TLR1 and TLR2 and of the Pro681His mutant of TLR2. The structures have a large conserved surface patch that also contains the site of the Lps(d) mutation. Mutagenesis and functional studies confirm that residues in this surface patch are crucial for receptor signalling. The Lps(d) mutation does not disturb the structure of the TIR domain itself. Instead, structural and functional studies indicate that the conserved surface patch may mediate interactions with the down-stream MyD88 adapter molecule, and that the Lps(d) mutation may abolish receptor signalling by disrupting this recruitment.

Amino Acid Sequence↗

PubMed2000

The Chinese anti-inflammatory and immunosuppressive herbal remedy Tripterygium wilfordii Hook F.

Various preparations of Tripterygium wilfordii Hook F (TwHF) have been used in the treatment of a number of autoimmune and inflammatory diseases since the 1960s. Accumulated data from the clinical trials suggest efficacy of this treatment in a number of rheumatic diseases, including rheumatoid arthritis and systemic lupus erythematosus. Studies on the relationship of the chemical components of TwHF and its immunosuppressive and anti-inflammatory effects suggest that diterpenoid compounds with epoxide groups account for the therapeutic effects of this herbal remedy. This herbal remedy is therefore a unique and powerful alternative therapy for autoimmune and inflammatory diseases.

Animals↗

PubMed2000

Correlation of genetic polymorphism of cytochrome P4502D6 with dextromethorphan oxidative metabolism in Chinese.

OBJECTIVE: To determine the genetic mechanism of dextromethorphan oxidative polymorphism in Chinese subjects. METHODS: CYP2D6 genotype was analyzed by polymerase chain reaction (PCR) and Hph I restriction fragment length polymorphism (RFLP) techniques in 119 healthy Chinese subjects. RESULTS: The gene frequency of CYP2D6*10B was 58.4%, including 13(10.9%) of homozygous wild type(w/w), 33 (27.7%) of homozygous mutant(m/m), and 73(61.3%) of heterozygous genotypes(m/w). Twenty-nine subjects out of 42 intermediate metabolizers(70%) of dextromethorphan were homozygous for CYP2D6*10B. One poor metabolizer subject also showed an m/m genotype. Besides, 10 Chinese subjects were tested and excluded for the presence of any of the six mutant alleles associated with poor metabolism of CYP2D6 in Caucasians. CONCLUSION: The CYP2D6*10B allele containing the C(188)--> T mutation is the major cause of CYP2D6 polymorphism in relation to diminished dextromethorphan oxidative capacity in Chinese subjects.

Adolescent↗

PubMed2000

Hepatitis B virus X protein activates expression of IGF-IR and VEGF in hepatocellular carcinoma cells.

OBJECTIVE: The expression of insulin-like growth factor I receptor (IGF-IR) and the vascular endothelial growth factor (VEGF) in HepG(2) cells transfected with a hepatitis B virus X (HBx) expression vector was investigated in an attempt to study their possible relationship to the growth of HBx-induced hepatocellular carcinoma (HCC). METHODS: The eucaryotic expression vector of HBx gene was constructed and introduced into HepG(2) cells. The modified cell HepaG(2)-X was synchronized in a quiescent state by culture of serum deprivation. The IGF-IR and VEGF were analyzed by immunohistochemical and Western blot technique. RESULTS: The positive rate of IGF-IR expression was 84%A3% in the transfected HBx gene cells, 26%A4% in X(0) control cells. The positive rate of VEGF expressed x cells was 83%A5%, X(0) cells was 28%A6% (P<0.001). The level of IGF-IR and VEGF in serum-starved x modified cells was 1.5 times higher than that of synchronized X(0) modified cells. CONCLUSION: Since the IGF-IR is a very important growth factor in sustaining the tumor abnormal growth and the VEGF has a crucial role in inducting tumor angiogenesis, our findings indicate that HBx may play an important role in the processes of HCC by activating IGF-IR and VEGF gene expression.

Carcinoma, Hepatocellular↗

PubMed1999

Mutagenic drinking water and risk of male esophageal cancer: a population-based case-control study.

Drinking mutagenic downstream water from the Huangpu River was hypothesized to have increased the risk for male esophageal cancer in Shanghai, China. The authors conducted a population-based case-control study of a total of 71 esophageal cancer deaths and 1,122 controls collected during a 5-year follow-up period, 1984-1988, from four male cohorts born before January 1, 1944, living in four communities consuming water with different mutagenicities in the Shanghai area. The controls represented a 1% random sample of the defined living cohorts selected at the end of each of the 5 years of follow-up. Logistic regression showed an odds ratio of 2.77 (95% confidence interval: 1.52, 5.03) for drinking mutagenic downstream water from the river versus drinking nonmutagenic upstream water after controlling for possible confounders including age, disease history (hepatitis, cirrhosis, schistosomiasis, digestive tract ulcer), hazardous occupational history, pesticide exposure, lifestyle factors (cigarette smoking, tea intake, and alcohol intake), dietary habits (intake of pickled vegetables, maize, peanuts, and cured meat), education, poverty, urban environment, and water chlorination.

Adult↗

PubMed1999

Suppression of carrageenan-induced inflammation in vivo by an extract of the Chinese herbal remedy Tripterygium wilfordii Hook F.

OBJECTIVE AND DESIGN: The current studies investigated the effect of subacute administration of an ethyl acetate extract of the Chinese herbal remedy, Tripterygium wilfordii Hook F (TWHF) on the inflammatory response induced by carrageenan in the rat. MATERIALS AND SUBJECTS: F344 rats were randomly divided into 3 groups of seven animals. TREATMENT: The rats were treated orally for 5 days with either vehicle or an ethyl acetate extract of TWHF at a dose of 270 mg/kg, equivalent to 1/5 of the dose causing death in 50% of the animals. METHODS: Air pouches were induced subcutaneously on the backs of rats and injected with carrageenan on the last day of treatment. Sixteen hours after carrageenan challenge, the air pouches were removed and analyzed. Student's t-test was employed for statistical analysis. RESULTS: The number of exudate cells and the concentration of PGE2, nitrite and TNF-alpha in the exudate obtained from TWHF-treated animals were significantly reduced (by 69%, 78%, 57% and 77%, respectively) compared to that from vehicle-treated animals. mRNA for cyclooxygenase-2 was markedly suppressed in the air pouch lining tissue of TWHF treated rats (p < 0.001). In contrast, PGE2 content of the kidney and stomach and the production of PGE2, nitrite and TNF-alpha by spleen cells was not affected by treatment with TWHF. CONCLUSIONS: These results indicate that TWHF exerts a significant anti-inflammatory activity in vivo.

Acetates↗

PubMed1999

Predictors of compliance with recommended cervical cancer screening schedule: a population-based study.

BACKGROUND: The prevalence of routine cervical cancer screening and compliance with screening schedules are low compared to the Year 2000 objectives. Identifying predictors of routine screening and screening schedule compliance will help achieve these objectives. METHODS: We analyzed data from probability samples of 1,609 Missouri women responding to both the 1994 Behavioral Risk Factor Surveillance System (BRFSS) and the Missouri Enhanced Survey (ES). We generated prevalence odds ratios to identify predictors of non-compliance to cervical cancer screening guidelines. Also, among a sample of women reporting a reason for last Pap test, we estimated the relative odds of a screening v. diagnostic exam. RESULTS: In the combined probability sample, compliance with screening schedule was likely among women younger than 50 years of age and women who had either a recent mammography or a clinical breast exam. Being African-American, not experiencing a cost barrier when seeking medical care, having at least a high-school education and health coverage were each associated with an increased compliance with a screening schedule in the combined probability sample. Among women in the combined probability sample, whites, those who experienced no cost barrier to seeking medical care, the non-obese, and those who had a recent mammography were each more likely to have had a screening as opposed to a diagnostic exam. DISCUSSION: Cancer control and cardiovascular (CVD) prevention programs should consider jointly targeting those at high risk for cervical cancer and CVD because of aging and associated high-risk behavior such as non-compliance with cervical cancer screening, smoking, and obesity. Also, further research is needed to examine whether the increased compliance with cervical cancer screening guidelines among African American women may be in part due to higher occurrence of diagnostic Pap smears.

Adult↗

PubMed1999

[The transactivation of hepatitis B virus X protein on the expression of Fas ligand in HepG2 cells].

OBJECTIVE: To study the effect of hepatitis B virus x (HBx) protein on the expression of Fas Ligand in HepG2 cells. METHODS: The open reading frame of HBx gene was obtained from HBV genome (subtype adw) digested with Nco I and Bgl II, then cloned into pCEP4. The reconstructive plasmid pCEP4x was transfected into HepG2 cells by electroportion method. After selecting with hygromycin B, resistant clonies were obtained. The expressions of HBx gene and Fas Ligand gene were detected by RT-PCR. Immunohistochemical staining and western blot analysis. RESULTS: It showed that Fas Ligand gene expressed in the modified HepG2 cells transfected with plasmid pCEP4x. CONCLUSIONS: The results suggest the expression of Fas Ligand in HepG2 cells could be activated by HBx protein.

Cell Line↗

PubMed1998

Relation of hemoglobin measured at different times in pregnancy to preterm birth and low birth weight in Shanghai, China.

This paper addresses two questions: 1) What is the relation of hemoglobin in the second gestational month to preterm birth and low birth weight? 2) How does the relation differ when hemoglobin in the fifth or eighth month or the lowest pregnancy hemoglobin are examined in place of first trimester values? These relations were examined prospectively in 829 women from Shanghai, China in 1991-1992. The population was nearly homogeneous by race, parity, antenatal care, and smoking. Rates of birth outcomes were compared between hemoglobin categories based on 10 g/liter groupings, with 110-119 g/liter as the reference group. Rates of low birth weight and preterm birth (but not small-for-gestational age) were related to early pregnancy hemoglobin concentration in a U-shaped manner. The relative risks (95% confidence intervals) for preterm birth in women by g/liter of hemoglobin were 2.52 (0.95-6.64) for > or = 130 g/liter, 1.11 (0.41-2.99) for 120-129 g/liter, 1.64 (0.77-3.47) for 100-109 g/liter, 2.63 (1.17-5.90) for 90-99 g/liter, and 3.73 (1.36-10.23) for 60-89 g/liter. Use of hemoglobin values in the fifth or eighth month attenuated the association with preterm birth. When lowest pregnancy hemoglobin values were used, the association of anemia with both outcomes was obscured, and risk of preterm birth at high hemoglobin values increased dramatically.

Adult↗

PubMed1998

The relationship between synonymous codon usage and protein structure.

The hypothesis that synonymous codon usage is related to protein three-dimensional structure is examined by investigating the correlation between synonymous codon usage and protein secondary structure. All except two codons in E. coli show the same secondary structural preference for alpha-helix, beta-strand or coil as that of amino acids to be encoded by the respective codons, while 17 codons show secondary structural bias in mammalian proteins. The results indicate that there is no significant correlation between synonymous codon usage and protein secondary structure in E. coli, but there is a correlation in mammals. It could be deduced that synonymous codons carry much less structural information in prokaryotes than in eukaryotes due to their divergent evolutionary mechanism.

Animals↗

PubMed1998

Distribution of catechol-O-methyltransferase expression in human central nervous system.

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is a ubiquitous enzyme crucial to catechol metabolism. Two isoforms exist in the human central nervous system (CNS) and they are encoded by two transcripts (1.3 and 1.5 kb) in most human tissues. Using two alpha-32P-labeled probes, we found only the 1.5 kb transcript in all 16 regions of the human CNS using commercially available Northern blots. Spinal cord had the highest and amygdala had the lowest levels of expression. The other CNS regions shared a similar level of expression. The distributions of COMT gene expression relative to whole brain between both probes were significantly correlated. Our study shows that the expression of the 1.5kb transcript is crucial for COMT activity in all regions of the human CNS.

Blotting, Northern↗

PubMed1998

Effects of Tripterygium wilfordii hook F extracts on induction of cyclooxygenase 2 activity and prostaglandin E2 production.

OBJECTIVE: Extracts of the Chinese herbal remedy Tripterygium wilfordii Hook F (TWHF) have been reported to be effective in the treatment of patients with a variety of inflammatory and autoimmune diseases, but the mechanism of this therapeutic effect has not been completely delineated. The present study was designed to assess the effects of TWHF on the in vitro synthesis of prostaglandin E2 (PGE2) and on the expression of the cyclooxygenase isoforms, COX-1 and COX-2, in various human cell types. METHODS: Monocytes from human peripheral blood (HM), fibroblasts from rheumatoid arthritis synovial tissue (RASF), human neonatal foreskin fibroblasts (HFF), and the histiocytic cell line U937 were cultured for designated time periods with or without lipopolysaccharide (LPS), and in the presence or absence of varying concentrations of the following inhibitors: the methanol/chloroform (T2) extract of TWHF, the ethyl acetate (EA) extract of TWHF, a purified diterpenoid component of TWHF (triptolide), dexamethasone, and indomethacin. Culture supernatants were harvested for PGE2 content assays. Total RNA was extracted from the cells and analyzed for COX-1 and COX-2 messenger RNA (mRNA) expression using reverse transcriptase-polymerase chain reaction or Northern blotting. RESULTS: Both the T2 and EA extracts inhibited PGE2 synthesis in the LPS-stimulated HM, RASF, and HFF cells, which was reflected by a marked suppression in the levels of mRNA for COX-2. In contrast, neither extract inhibited PGE2 production in U937 cells that did not express COX-2. Triptolide also inhibited LPS-stimulated induction of COX-2 mRNA and synthesis of PGE2, at the same inhibitory concentration as seen with the EA extract. The effects of T2, EA, and triptolide paralleled the inhibitory action of dexamethasone. CONCLUSION: The data indicate that both the T2 and EA extracts of TWHF, as well as the triptolide component, inhibit PGE2 production in a variety of human cells by blocking the up-regulation of COX-2.

Acetates↗

PubMed1998

Ca2+ influx regulates BDNF transcription by a CREB family transcription factor-dependent mechanism.

CREB is a transcription factor implicated in the control of adaptive neuronal responses. Although one function of CREB in neurons is believed to be the regulation of genes whose products control synaptic function, the targets of CREB that mediate synaptic function have not yet been identified. This report describes experiments demonstrating that CREB or a closely related protein mediates Ca2+-dependent regulation of BDNF, a neurotrophin that modulates synaptic activity. In cortical neurons, Ca2+ influx triggers phosphorylation of CREB, which by binding to a critical Ca2+ response element (CRE) within the BDNF gene activates BDNF transcription. Mutation of the BDNF CRE or an adjacent novel regulatory element as well as a blockade of CREB function resulted in a dramatic loss of BDNF transcription. These findings suggest that a CREB family member acts cooperatively with an additional transcription factor(s) to regulate BDNF transcription. We conclude that the BDNF gene is a CREB family target whose protein product functions at synapses to control adaptive neuronal responses.

Animals↗

PubMed1998

Predictors of mammography utilization in Missouri, 1993-1994.

Mammography utilization data were studied for 915 women from a combined sample of 1994 Missouri Behavioral Risk Factor Surveillance System and a Special Breast and Cervical Cancer Control Project Evaluation Survey, as well as similar data from 6,784 new participants in Missouri's Breast and Cervical Cancer Control Project during 1993-1994. Among women aged 40 and over, having some college education and having health insurance coverage were associated with a higher likelihood of ever having a mammogram. Education, age, health care, Pap testing, and smoking were identified as important predictors of compliance with recommended schedule of yearly mammography among women aged 50 and over.

Adult↗

PubMed1998

[Will chronic nonproductive cough with bronchial hyperresponsiveness be cough variant asthma?].

OBJECTIVE: The clinical characteristics of the patients suffered from chronic nonproductive cough with bronchial hyperresponsiveness were analyzed, so as to evaluate the value of measurement of bronchial responsiveness in diagnosis of cough variant asthma (CVA). METHOD: 124 patients with chronic nonproductive cough were divided into two groups after the measurement of bronchial responsiveness: cough bronchial hyperresponsiveness positive group (CBH-P, n = 35) and cough bronchial hyperresponsiveness negative group (CBH-N, n = 33). Routine pulmonary function, positive rate of antigen-skin pitting lest, count of blood eosinophil cells, level of blood IgE, positive rate of prednisone test and the number of development of classical asthma in two-year following up were studied. RESULT: The percentage of FEV1.0 in group CBH-P was significantly lower than in group CBH-N, but antigen-skin pitting test, count of blood eosinophil cells, prednisone test and the number of development of classic asthma in two-year following up were all higher than in the latter group. In group CBH-P, there was no significant difference in positive rate of antigen-skin pitting test, routine pulmonary function, reacting threshold(Dmin) and wheezing threshold (DCW/Dmin) between the patients who developed classic asthma and those who did not. CONCLUSION: The measurement of bronchial responsiveness is important for the diagnosis of CVA, but it is not the only diagnostic criteria and should be combined with other clinical data.

Adult↗

PubMed1997

Lymphohematopoietic cancers and butadiene and styrene exposure in synthetic rubber manufacture.

The described nested case-control study of lymphohematopoietic cancers occurring in a cohort of synthetic rubber production workers was conducted to determine the associations of these cancers with exposure to butadiene and styrene. Cases have been confirmed through hospital record review of 95 percent of the cancers. Exposures are based on measured values of the two chemicals from personal monitoring data in seven of the eight plants under study. The results indicate that the risk of leukemia increases with exposure to a time-weighted average butadiene measure. The odds ratio at only 1 ppm average butadiene exposure is 1.50 (95% CI 1.07, 2.10). Work in specific areas also contributes to the risk, possibly because these areas have not been completely characterized for differences in butadiene exposure. Hodgkins disease is also associated with butadiene exposure. Multiple myeloma, lymphosarcoma, and all lymphomas are associated with exposure to styrene. Since workers in this industry are apparently exposed to two carcinogenic agents, further effort must be made to distinguish the exposures to each chemical over time and to characterize their interrelationship with the risk of cancers of the lymphohematopoietic system.

Butadienes↗

PubMed1997

Distinct biochemical signals characterize agonist- and altered peptide ligand-induced differentiation of naive CD4+ T cells into Th1 and Th2 subsets.

We have recently shown that altered peptide ligands influence differentiation of CD4+ T cells into Th1 and Th2 subsets. In the present study, we have examined the biochemical signals in naive CD4+ T cells after priming with altered peptide ligand (APL) that correlate with differences in cytokine expression. Although we observed zeta-chain phosphorylation in APL-stimulated cells, other signaling events such as ZAP70 and Lnk phosphorylation are not initiated. This altered pattern observed in the early phosphorylation events correlates with a distinct Ca2+ mobilization pattern that characterizes APL-stimulated cells. By changing the calcium signaling environment during T cell priming, we present data indicating that qualitative differences in calcium mobilization are associated with differentiation of naive CD4+ T cells into Th1- and Th2-like effector subsets.

Amino Acid Sequence↗