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Biomedical subjects

S Zhou

Publications and source records attributed to S Zhou.

At least 325 records · Page 18Linked to original sources
PubMed1997

Cloning and characterization of an essential Saccharomyces cerevisiae gene, TAF40, which encodes yTAFII40, an RNA polymerase II-specific TATA-binding protein-associated factor.

In this report we describe the cloning and initial characterization of TAF40, a gene that encodes a yeast TATA-binding protein-associated factor (yTAF) of Mr = approximately 40,000. This gene has many similarities to other yTAFs described thus far in that it is present at a single copy per haploid genome, it is essential for viability, and the deduced protein sequence of yTAF40 exhibits similarity to previously described human and Drosophila TAFIIs. Immunological studies confirm that yTAF40 protein is a subunit of a large multiprotein TATA-binding protein-TAF complex that contains a subset of the total number of the yTAFs present in yeast cell extracts. Transcription reactions performed using yeast whole cell extracts reveal that of the three nuclear RNA polymerases only RNA polymerase II function is abrogated when yTAF40 and associated proteins are immunodepleted from solution, indicating that the functionality of the multiprotein complex containing yTAF40 is RNA polymerase II-specific. By these criteria yTAF40 appears to encode a bona fide RNA polymerase II-specific TAF, and thus the protein that it encodes has been termed yTAFII40.

Amino Acid Sequence↗
PubMed1997

Measurement of CD69 induction in the assessment of immune function in asymptomatic HIV-infected individuals.

Peripheral blood mononuclear cells from many asymptomatic HIV-infected patients exhibit defects in cytokine production and impaired proliferative responses in vitro but the mechanisms underlying this subclinical immune deficiency are controversial. To determine whether abnormalities in the earliest events following receptor engagement may help to explain the in vitro immune dysfunction, we measured the inducibility of the early activation marker CD69 in T cells from asymptomatic HIV-infected individuals in response to stimulation with anti-CD2 or anti-CD3 mAb. In a whole blood assay, we found that induction of CD69 was markedly impaired in CD4+ T cells from later-stage HIV-infected patients (CD4 counts 200-400/mm3) compared to uninfected controls. Among early stage patients (CD4 > 400/mm3), a subset (29%) had impaired CD69 induction. CD69 responses were equally depressed after stimulation through the CD3 or CD2 receptor pathways. Survey of a panel of immunophenotypic markers and propensity for apoptosis demonstrated a significant association between depressed induction of CD69 and decreased percentages of CD4+CD26+ and CD4+CD95+ cells but no association with the level of apoptosis. These data indicate that defects in T lymphocyte activation through CD3 and CD2 can be measured within hours of receptor stimulation in asymptomatic HIV-infected individuals and might be useful to monitor as an indicator of immune function in these patients.

Antigens, CD↗
PubMed1997

Abnormal compartmentalization of cartilage matrix components in mice lacking collagen X: implications for function.

There are conflicting views on whether collagen X is a purely structural molecule, or regulates bone mineralization during endochondral ossification. Mutations in the human collagen alpha1 (X) gene (COL10A1) in Schmid metaphyseal chondrodysplasia (SMCD) suggest a supportive role. But mouse collagen alpha1 (X) gene (Col10a1) null mutants were previously reported to show no obvious phenotypic change. We have generated collagen X deficient mice, which shows that deficiency does have phenotypic consequences which partly resemble SMCD, such as abnormal trabecular bone architecture. In particular, the mutant mice develop coxa vara, a phenotypic change common in human SMCD. Other consequences of the mutation are reduction in thickness of growth plate resting zone and articular cartilage, altered bone content, and atypical distribution of matrix components within growth plate cartilage. We propose that collagen X plays a role in the normal distribution of matrix vesicles and proteoglycans within the growth plate matrix. Collagen X deficiency impacts on the supporting properties of the growth plate and the mineralization process, resulting in abnormal trabecular bone. This hypothesis would accommodate the previously conflicting views of the function of collagen X and of the molecular pathogenesis of SMCD.

Animals↗
PubMed1997

Drosophila TFIIE: purification, cloning, and functional reconstitution.

We present a physical and molecular genetic characterization of Drosophila melanogaster TFIIE (dTFIIE), a component of the basal RNA polymerase II transcription apparatus. We have purified dTFIIE to near homogeneity from nuclear extracts of Drosophila embryos and found that it is composed of two subunits with apparent molecular weights of 55 and 38 kDa. Peptide sequence information derived from the two subunits was used to isolate the corresponding cDNA clones, revealing that dTFIIE and human TFIIE share extensive amino acid similarity. Functional conservation was demonstrated by the ability of bacterially expressed dTFIIE to substitute for human TFIIE in an in vitro transcription assay reconstituted from purified components. Cytological mapping analysis shows that both subunits are encoded by single copy genes located on chromosome III.

Amino Acid Sequence↗
PubMed1997

Genome analysis in Neurospora crassa; cloning of four loci arginine-1 (arg-1), methionine-6 (met-6), unknown-7 (un-7), and ribosome production-1 (rip-1) and associated chromosome walking.

We have cloned four Neurospora crassa genes by complementation analysis. Cloned genes include the arginine-1 (arg-1), methionine-6 (met-6), unknown-7 (un-7), and ribosome production-1 (rip-1) loci. Chromosome walks were initiated in ordered cosmid libraries from the cloned loci. A total of about 700 kb of the Neurospora genome is covered in these walks.

Arginine↗
PubMed1997

Anti-lipid peroxidization effect of huangdan on chronic renal failure in rats.

The activity of superoxide dismutase (SOD) in renal cortex and erythrocytes, the level of lipid peroxidant (LPO) in plasma, renal function and morphology of leftover kidney were examined in rats. The results showed that Huangdan capsule could slow down the increase of BUN and Scr, promote the SOD activity in renal cortex and erythrocytes, reduce the level of LPO in plasma and delay the renal pathological changes in 5/6 nephrectomized rats. The mechanism of Huangdan capsule's antiperoxidant effect, its effect on the renal pathological changes and relationship between the two effects were also discussed.

Animals↗
PubMed1997

Effect of different drugs on end-tidal carbon dioxide during rodent CPR.

The purpose of this study was to investigate the effect of non-adrenergic agents on cardiopulmonary resuscitation (CPR) and end-tidal CO2 (ETCO2) during CPR in a rodent model. Our results suggested that: 1) coronary perfusion pressure (CPP) after drugs infusion was increased significantly by methoxamine, arginine vasopresin (AVP) and angiotension-II (ANG-II), but not by endothelin-1 (ET-1); 2) ETCO2 prior to defibrillation was decreased significantly by a pure alpha 1 adrenergic agents, methoxamine and were increased significantly by non-adrenergic agents, ANG-II and ET-1 during rodent CPR; 3) a significant positive correlation between ETCO2 and CPP was observed in AVP group, suggesting that AVP have little effect on pulmonary circulation; and 4) methoxamine, AVP and ANG-II have similar effect on resuscitability during rodent CPR.

Adrenergic alpha-Agonists↗
PubMed1997

Visualisation of capillaries in human skeletal muscle.

A double staining method combining Ulex europaeus agglutinin I lectin (UEA-I) and collagen type IV staining was used to determine the capillary density and the number of capillaries relative to different fibre types in human skeletal muscles. The result of this combined staining was compared with that of other staining methods including amylase-periodic acid Schiff (PAS), UEA-I, anti-collagen type IV and anti-von Willebrand factor. Muscle biopsy specimens, 12 from M. vastus lateralis and 6 from M. soleus, were obtained from 18 healthy young men. Compared with amylase-PAS staining, double staining showed a larger number of capillaries surrounding type I (+9.6%), type IIA (+8.6%) and type IIB (+11.6%) fibres in the M. vastus lateralis specimens (P < 0.001 for all differences). The capillary to fibre ratio (cap fibre-1) and the capillary density (cap.mm-2) were 8.3% (P < 0.002) and 7.9% (P < 0.001) larger, respectively. In the M. soleus specimens, cap.fibre-1 and cap.mm-2 were 7.4 and 9.9% larger, respectively, by double staining compared with PAS staining. Further comparisons showed that the cap.fibre-1 and cap.mm-2 obtained with double staining were similar to the values determined by the UEA-I staining, but greater than that measured by the collagen type IV method. The double staining gave a more marked stain of capillaries and revealed muscle fibre borders clearly, which is an advantage in studies that require comparisons between serial sections using computerised image analyses. It is concluded that the double staining method is superior to either the UEA-I, collagen type IV or the traditional amylase-PAS staining methods in analysing capillary density of normal human skeletal muscle.

Adolescent↗
PubMed1997

Plasma norepinephrine increased during coronary occlusion in hypertensive pigs that developed ventricular fibrillation.

Although hypertension is associated with increased risk of sudden cardiac death, the mechanisms involved remain enigmatic. Little is known about hemodynamic and plasma catecholamine concentration changes during coronary artery occlusion in hypertensive subjects. To study this, 30 pigs were implanted with catheters in the aorta and a silk snare around the left anterior descending coronary artery that could later be pulled to permanently occlude the artery. Perinephritic hypertension was induced in 14 of the animals over 3 weeks by wrapping one kidney in silk followed by contralateral nephrectomy. Coronary artery occlusion (CAO) was carried out in all pigs in the conscious resting state. Ventricular fibrillation (VF) developed in 50% of each group within 15 min after coronary artery occlusion. The hypertensive VF group showed an increase in norepinephrine concentration of 112 +/- 46%; a significantly greater increase than the intact VF group, which showed a 29 +/- 7% increase in norepinephrine concentration 5 min after coronary artery occlusion (p < 0.05).

Animals↗
PubMed1997

SOX9 directly regulates the type-II collagen gene.

Mutations in human SOX9 are associated with campomelic dysplasia (CD), characterised by skeletal malformation and XY sex reversal. During chondrogenesis in the mouse, Sox9 is co-expressed with Col2a1, the gene encoding type-II collagen, the major cartilage matrix protein. Col2a1 is therefore a candidate regulatory target of SOX9. Regulatory sequences required for chondrocyte-specific expression of the type-II collagen gene have been localized to conserved sequences in the first intron in rats, mice and humans. We show here that SOX9 protein binds specifically to sequences in the first intron of human COL2A1. Mutation of these sequences abolishes SOX9 binding and chondrocyte-specific expression of a COL2A1-driven reporter gene (COL2A1-lacZ) in transgenic mice. Furthermore, ectopic expression of Sox9 trans-activates both a COL2A1-driven reporter gene and the endogenous Col2a1 gene in transgenic mice. These results demonstrate that COL2A1 expression is directly regulated by SOX9 protein in vivo and implicate abnormal regulation of COL2A1 during, chondrogenesis as a cause of the skeletal abnormalities associated with campomelic dysplasia.

Animals↗
PubMed1997

Serum levels of virus burden in early-stage human immunodeficiency virus type 1 disease in women.

The fundamental clinical, viral, and immunologic features of early-stage human immunodeficiency virus type 1 (HIV-1) disease were examined in a seroprevalent cohort of 28 men and 14 women assessed longitudinally at three equally dispersed time points over a mean of 43 months. There were no gender differences in the relative risk of developing AIDS-defining end points or death. The median serum RNA levels assessed at the three study time points were 3.3-, 4.9-, and 1.5-fold lower, respectively, in women than in men. This suggests that while serum virus load may be as powerful a correlate of disease status in women as it is in men, the absolute values of the virus levels may be different in the 2 populations. These observations may have implications for the interpretation of levels of virus burden in women for the assessment of disease progression, transmission, and treatment.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Reliability of using the D-max method to define physiological responses to incremental exercise testing.

The purpose of this study was to examine the reliability of using a mathematical method, D-max, to define blood lactate kinetics in response to an incremental exercise test, and to compare the physiological responses corresponding to the workload at D-max with those at the traditional 4 mmol l-1 lactate threshold and ventilatory thresholds. Ten male endurance trained athletes, with an average (+/- SD) age of 25.6 +/- 8.2 years and maximal oxygen consumption of 64.0 +/- 1.7 ml kg-1 min-1, performed an incremental cycling test on two occasions separated by four weeks. The expired gas was analysed on-line and plasma lactate concentration was analysed for each workload and at exhaustion. The lactate response to exercise was represented by a third-order polynomial regression curve. The D-max was defined as the point on the regression curve that yields the maximal distance to the straight line formed by the two end points of the curve. The results demonstrated a high test-retest reliability (intraclass correlation coefficients 0.77-0.93, p < 0.01) in oxygen consumption, heart rate and exercise intensity at both D-max point and exhaustion. No significant differences were found in the mean values of the variables between the two tests. It is concluded that the D-max appears to be a reliable method for defining the individual physiological responses to exercise tests, with the advantage of objectivity. However, there is no evidence to support the theory that the exercise intensity defined by the D-max method is superior to that defined by other methods to prescribe training intensity or predict aerobic performance for athletes. Further investigations are warranted to examine the validity of using this method in exercise prescription.

Adolescent↗
PubMed1997

Cheng's method for reconstruction of a functionally sensitive penis.

This article introduces a new surgical method for one-stage reconstruction of the penis. It is applied to the reconstruction of the microphallus as well as to traumatic cases with the residual stump of the amputated penis not less than 3 cm long. By transferring the original glans or the residual penile stump to the anterior portion of the newly reconstructed penile body with microsurgical techniques, we have thus rebuilt a penis with more satisfactory results in both appearance and erotic sensation. Seven patients are reported here who were operated on by this method and who have been followed up for 18 months to 10 years. The good results achieved and the method's advantages over other methods are demonstrated and discussed.

Adolescent↗
PubMed1997

Linear IgA disease: a report of two dermal binding sera which recognize a pepsin-sensitive epitope (?NC-1 domain) of collagen type VII.

Linear IgA disease is a subepidermal blistering disease characterized by IgA autoantibody deposition at the basement membrane zone of skin and mucosa. The antigens targeted in linear IgA disease have been defined by their molecular weight and localization. It has been proposed that a minority of linear IgA disease sera that bind to the dermal aspect of salt-split skin target collagen type VII. We have identified two patients with linear IgA disease using dermal binding IgA autoantibodies on salt-split skin which recognize collagen type VII by immunoblot analysis. The reactive epitope was destroyed by the proteolytic enzymes pepsin, which destroys the NC-1 domain of collagen type VII, and protease type VIII. Localization studies compared the IgA autoantibodies from these patients with the monoclonal antibody LH7.2 to the NC-1 domain of collagen type VII and showed colocalization on a dermal cylindroma tumour tissue, and a similar distribution with immunogold electron microscopy, using purified blister fluid from one patient. We propose from these results that the IgA autoantibodies from these two patients recognize the NC-1 domain of collagen type VII, the classical immunodominant epitope for epidermolysis bullosa acquisita.

Adult↗
PubMed1997

Does exogenous coenzyme Q10 affect aerobic capacity in endurance athletes?

The effect of orally supplemented coenzyme Q10 (CoQ10) on plasma CoQ10 concentration and aerobic capacity in endurance athletes was evaluated. Eighteen volunteer male road cyclists and triathletes, 8 in a CoQ10 supplementation group (QG) and 10 in a placebo group (PG), successfully completed the experimental protocol. Subjects were evaluated during and following graded cycling exercise tests, which were performed before and after 28 days of supplementation with 1 mg.kg-1.day-1 of CoQ10 or placebo. The presupplementation plasma CoQ10 concentration was significantly increased from 0.91 +/- 0.13 microgram.ml-1 to 1.97 +/- 0.27 microgram.ml-1 in QG following supplementation (p < .05). However, the CoQ10 supplementation regime had no consistently significant effect on oxygen uptake, anaerobic and respiratory compensation thresholds, blood lactate, glucose and triglyceride kinetics, heart rate, and blood pressure during and after graded cycling to exhaustion.

Administration, Oral↗
PubMed1997

VirB1, a component of the T-complex transfer machinery of Agrobacterium tumefaciens, is processed to a C-terminal secreted product, VirB1.

During genetic transformation of plant cells by Agrobacterium tumefaciens, 11 VirB proteins and VirD4 are proposed to form a transmembrane bridge to transfer a DNA-protein complex (T-complex) into the plant cytoplasm. In this study, the localization of the first product of the virB operon, VirB1, was studied in detail. While full-length VirB1 localized mostly to the inner membrane, an immunoreactive VirB1 product was found as soluble processed form, designated VirB1*. Equal amounts of VirB1* could be detected in concentrated culture supernatants versus associated with the cell. VirB1* was purified from the supernatant of vir-induced cells by ammonium sulfate precipitation and Q-Sepharose chromatography. Sequence analysis of the N terminus of VirB1* localized the processing site after amino acid 172 of VirB1. Cell-associated VirB1* was partly removed by vortexing, suggesting a loose association with the cell or active secretion. However, cross-linking and coimmunoprecipitation showed a close association of cell-bound VirB1* with the VirB9-VirB7 heterodimer, a membrane-associated component of the T-complex transfer machinery. Homologies of the N-terminal part of VirB1 to bacterial transglycosylases suggest that it may assist T-complex transfer by local lysis of the bacterial cell wall, whereas the exposed localization of the C-terminal processing product VirB1* predicts direct interaction with the plant. Thus, VirB1 may be a bifunctional protein where both parts have different functions in T-complex transfer from Agrobacterium to plant cells.

Agrobacterium tumefaciens↗
PubMed1997

Genetic immunization with adeno-associated virus vectors expressing herpes simplex virus type 2 glycoproteins B and D.

Intramuscular injection of mice with an adeno-associated virus (AAV) vector expressing herpes simplex virus type 2 glycoprotein B led to the generation of both gB-specific major histocompatibility complex class I-restricted cytotoxic T lymphocytes and anti-gB antibody. AAV-mediated immunization was more potent than plasmid DNA or protein in generating antibody responses.

Animals↗