Biomedical subjects

Hui Zhang

Publications and source records attributed to Hui Zhang.

At least 361 records · Page 20Linked to original sources

PubMed2002

Residual HIV-1 disease in seminal cells of HIV-1-infected men on suppressive HAART: latency without on-going cellular infections.

BACKGROUND: HIV-1-infected men on suppressive highly active antiretroviral therapy (HAART) have a reduction of viral replication in vivo, but HIV-1 RNA is still detectable by certain ultrasensitive reverse transcriptase-PCR assays in blood plasma. Replication-competent virus can also be isolated from both peripheral blood mononuclear cells (PBMC) and seminal cells of these patients. Despite HAART, on-going in vivo infection of HIV-1-seropositive patients' PBMC was demonstrated by the detection of episomal HIV-1 moieties, known as HIV-1 two-long terminal repeat (2-LTR) DNA circles. METHODS: The present study analyzes whether new cellular infections occur in vivo in seminal cells of HIV-1-infected men on suppressive HAART. PBMC and seminal cells were isolated from a cohort of HIV-1-seropositive men taking suppressive HAART (< 50 copies HIV RNA/ml blood plasma). Viral growth assays were performed in vitro, as well as semi-quantitative PCR to detect HIV-1 2-LTR circular DNA in PBMC and seminal mononuclear cells. RESULTS: Viral growth in vitro was demonstrated in 16 out of 28 (57%) patients' PBMC, and in five patients' seminal cells (18%). Although 18 patients' PBMC were positive for HIV-1 2-LTR DNA circles, importantly, 2-LTR circular DNA was not detected in any semen sample, even when replication-competent HIV-1 virus had been recovered from a patient's seminal cells by viral co-culture assays. CONCLUSIONS: The current study suggests that in HIV-1-infected men treated with suppressive HAART, new cellular infections occur in PBMC, but that new infections do not take place in seminal cells in vivo. Thus, these findings suggest that mainly latent HIV-1 occurs in seminal cells of men on suppressive HAART, which may be a compartment-specific mechanism of residual HIV-1 disease.

Antiretroviral Therapy, Highly Active↗

PubMed2002

Molecular cloning and genomic structure of an interleukin-8 receptor-like gene from homozygous clones of rainbow trout (Oncorhynchus mykiss).

Chemokines are small proteins (70-100 amino acids) which play an important role in recruitment and activation of leucocytes to migrate to the site of inflammation. Based on the position of the first two conserved cysteines, chemokines are classified into four subfamilies: C, CC, CXC and CX3C. To date, many members of CC and CXC have been found and studied extensively [1]. Chemokines exert effects on their target cell via chemokine receptors, which are G-protein coupled receptors containing seven transmembrane domains with an extracellular N-terminus and an intracellular C-terminus [2]. Interleukin 8 (IL-8) belongs to the CXC chemokine subfamily. It can activate and attract migratory neutrophils to an inflammation site. Two IL-8 receptors, CXCR1 and CXCR2, have been identified in mammals [3-6]; both of these receptors have high affinity for IL-8 and are expressed on the neutrophil. CXCR1 just binds IL-8; however, CXCR2 binds IL-8 and other structurally related chemokines such as growth-related oncogene (GRO) a, GRObeta, GROgamma, neutrophil-activating peptide-2 (NAP-2) and epithelial cell-derived neutrophil activating peptide-78 (ENA-78) [7, 8]. Several studies on fish chemokine receptors have been reported [9-11]. Thus far, however, IL-8 and CXCR1 and CXCR2 proteins from rainbow trout have not been reported: however, the sequence of a rainbow trout IL-8 has been noted (GenBank Accession No. AJ279069 [12]). Cloning of the IL-8 receptor is important to study the function of IL-8/CXCR1 and (CXCR2) in inflammation and signal transduction in fish. This paper reports the molecular cloning and genomic structure of an IL-8 receptor-like gene from four homozygous clones of rainbow trout: Oregon State University (OSU), Hot Creek (HC), Arlee (AR) and Swanson (SW).

Amino Acid Sequence↗

PubMed2002

Interactions of oxidative stress with thiamine homeostasis promote neurodegeneration.

Thiamine-dependent processes are diminished in brains of patients with several neurodegenerative diseases. The decline in thiamine-dependent enzymes can be readily linked to the symptoms and pathology of the disorders. Why the reductions in thiamine linked processes occur is an important experimental and clinical question. Oxidative stress (i.e. abnormal metabolism of free radicals) accompanies neurodegeneration and causes abnormalities in thiamine-dependent processes. The vulnerability of thiamine homeostasis to oxidative stress may explain deficits in thiamine homeostasis in numerous neurological disorders. The interactions of thiamine with oxidative processes may be part of a spiral of events that lead to neurodegeneration, because reductions in thiamine and thiamine-dependent processes promote neurodegeneration and cause oxidative stress. The reversal of the effects of thiamine deficiency by antioxidants, and amelioration of other forms of oxidative stress by thiamine, suggest that thiamine may act as a site-directed antioxidant. The data indicate that the interactions of thiamine-dependent processes with oxidative stress are critical in neurodegenerative processes.

Animals↗

PubMed2002

CAND1 binds to unneddylated CUL1 and regulates the formation of SCF ubiquitin E3 ligase complex.

The SCF ubiquitin E3 ligase regulates ubiquitin-dependent proteolysis of many regulatory proteins such as p27(Kip1), IkappaB, and beta-catenin. We report the isolation of a CUL1 binding protein, p120(CAND1). We found the majority of CUL1 is in a complex with CAND1 and ROC1 independent of SKP1 and F box protein SKP2. Both in vivo and in vitro, CAND1 prevents the binding of SKP1 and SKP2 to CUL1 while dissociation of CAND1 from CUL1 promotes the reverse reaction. Neddylation of CUL1 or the presence of SKP1 and ATP causes CAND1 dissociation. Our data suggest that CAND1 regulates the formation of the SCF complex, and its dissociation from CUL1 is coupled with the incorporation of F box proteins into the SCF complex, causing their destabilization.

Adenosine Triphosphate↗

PubMed2002

A contextual framework for characterizing motility and chemotaxis mutants in Dictyostelium discoideum.

In the natural aggregation process, Dictyostelium amoebae relay the cAMP signal outwardly through the cell population as symmetric, nondissipating waves. Each cell in turn responds in a specific manner to the different phases of the wave. In the front of each wave, each cell experiences an increasing temporal gradient and positive spatial gradient of cAMP; at the peak of each wave, each cell experiences a cAMP concentration inhibitory to locomotion; and in the back of each wave, each cell experiences a decreasing temporal and negative spatial gradient of cAMP. Protocols are described to analyze the basic motile behavior of mutant cells in the absence of a chemotactic signal, and to test the responsiveness of mutant cells to the individual temporal, spatial and concentration components of a natural wave. The results of such an analysis can then be used to develop realistic models of cell motility and chemotaxis. Examples are described in which this contextual framework has been applied to mutant cell lines. The results of these mutant studies result in a model in which independent parallel regulatory pathways emanating from different phases of the wave effect different phase-specific behaviors.

Animals↗

PubMed2002

Effects of valve dysfunction on Doppler Tei index.

BACKGROUND: Recently proposed Doppler Tei index, defined as the sum of isovolumic contraction time or mitral valve closure to aortic valve opening time and isovolumic relaxation time or aortic valve closure to mitral valve opening time divided by ejection time, is a simple measure which enables noninvasive estimation of combined systolic and diastolic function and prediction of patients' prognosis. However, effects of valve dysfunction on Tei index have not been investigated. This study was designed to compare Tei index before and after surgical valve replacement or repair to evaluate effects of valve dysfunction on Tei index. METHODS: Participants consisted of 76 consecutive patients with aortic or mitral valve surgery (26 patients with aortic stenosis [AS], 16 with aortic regurgitation, 17 with mitral stenosis, and 17 with mitral regurgitation). Doppler Tei index was evaluated before and after the surgery by obtaining (a-b)/b, where a is the interval between the cessation and onset of Doppler mitral filling flow and b is the aortic flow ejection time. RESULTS: Tei index significantly increased after surgery in patients with AS (0.38 +/- 0.07 to 0.49 +/- 0.06, P <.001), aortic regurgitation (0.60 +/- 0.20 to 0.70 +/- 0.18, P <.01), mitral stenosis (0.34 +/- 0.03 to 0.39 +/- 0.04, P <.01), and decreased with no significance in mitral regurgitation (0.50 +/- 0.03 to 0.46 +/- 0.03). Percent change in Tei index after valve surgery was maximal in patients with AS (27 +/- 6 vs 17 +/- 2 vs 16 +/- 6 vs -9% +/- 6%, AS vs aortic regurgitation vs mitral stenosis vs mitral regurgitation, P <.001). CONCLUSION: Tei index significantly changes after valve surgery especially in patients with AS. Considerations for the effects of valve dysfunction on Tei index are required for its application to evaluate ventricular function in patients with valve disease.

Adult↗

PubMed2002

A new phytosterone from Cyanotis arachnoidea.

From Cyanotis arachnoidea C.B. Clarke, a new phytosterone named cyanosterone A (1), along with three known compounds--beta-ecdysone (2), ajugasterone C (3) and beta-sitosterol (4) were isolated. The structure of the new compound was determined as 3beta,14alpha,20R,22R-tetrahydroxy-5alpha-cholest-7-en-6-one on the basis of physicochemical properties and spectral analysis.

Herbal Medicine↗

PubMed2002

Differential expression of methanogenesis genes of Methanothermobacter thermoautotrophicus (formerly Methanobacterium thermoautotrophicum) in pure culture and in cocultures with fatty acid-oxidizing syntrophs.

The expression of genes involved in methanogenesis in a thermophilic hydrogen-utilizing methanogen, Methanothermobacter thermoautotrophicus strain TM, was investigated both in a pure culture sufficiently supplied with H(2) plus CO(2) and in a coculture with an acetate-oxidizing hydrogen-producing bacterium, Thermacetogenium phaeum strain PB, in which hydrogen partial pressure was constantly kept very low (20 to 80 Pa). Northern blot analysis indicated that only the mcr gene, which encodes methyl coenzyme M reductase I (MRI), catalyzing the final step of methanogenesis, was expressed in the coculture, whereas mcr and mrt, which encodes methyl coenzyme M reductase II (MRII), the isofunctional enzyme of MRI, were expressed at the early to late stage of growth in the pure culture. In contrast to these two genes, two isofunctional genes (mtd and mth) for N(5),N(10)-methylene-tetrahydromethanopterin dehydrogenase, which catalyzes the fourth step of methanogenesis, and two hydrogenase genes (frh and mvh) were expressed both in a pure culture and in a coculture at the early and late stages of growth. The same expression pattern was observed for Methanothermobacter thermoautotrophicus strain DeltaH cocultured with a thermophilic butyrate-oxidizing syntroph, Syntrophothermus lipocalidus strain TGB-C1. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole proteins of M. thermoautotrophicus strain TM obtained from a pure culture and a coculture with the acetate-oxidizing syntroph and subsequent N-terminal amino acid sequence analysis confirmed that MRI and MRII were produced in the pure culture, while only MRI was produced in the coculture. These results indicate that under syntrophic growth conditions, the methanogen preferentially utilizes MRI but not MRII. Considering that hydrogenotrophic methanogens are strictly dependent for growth on hydrogen-producing fermentative microbes in the natural environment and that the hydrogen supply occurs constantly at very low concentrations compared with the supply in pure cultures in the laboratory, the results suggest that MRI is an enzyme primarily functioning in natural methanogenic ecosystems.

Acetates↗

PubMed2002

Control of DNA replication and chromosome ploidy by geminin and cyclin A.

Alteration of the control of DNA replication and mitosis is considered to be a major cause of genome instability. To investigate the mechanism that controls DNA replication and genome stability, we used the RNA silencing-interference technique (RNAi) to eliminate the Drosophila geminin homologue from Schneider D2 (SD2) cells. Silencing of geminin by RNAi in SD2 cells leads to the cessation of mitosis and asynchronous overreplication of the genome, with cells containing single giant nuclei and partial ploidy between 4N and 8N DNA content. The effect of geminin deficiency is completely suppressed by cosilencing of Double parked (Dup), the Drosophila homologue of Cdt1, a replication factor to which geminin binds. The geminin deficiency-induced phenotype is also partially suppressed by coablation of Chk1/Grapes, indicating the involvement of Chk1/Grapes in the checkpoint control in response to overreplication. We found that the silencing of cyclin A, but not of cyclin B, also promotes the formation of a giant nucleus and overreplication. However, in contrast to the effect of geminin knockout, cyclin A deficiency leads to the complete duplication of the genome from 4N to 8N. We observed that the silencing of geminin causes rapid downregulation of Cdt1/Dup, which may contribute to the observed partial overreplication in geminin-deficient cells. Analysis of cyclin A and geminin double knockout suggests that the effect of cyclin A deficiency is dominant over that of geminin deficiency for cell cycle arrest and overreplication. Together, our studies indicate that both cyclin A and geminin are required for the suppression of overreplication and for genome stability in Drosophila cells.

Animals↗

PubMed2002

Up-regulation of the expression of activins in the pancreatic duct by reduction of the beta-cell mass.

Activins expressed in progenitor cells of the pancreas regulate differentiation of endocrine cells during development. Neogenesis of beta-cells takes place in adult animals under some conditions, and beta-cells are thought to arise from precursors locating in the pancreatic duct. In the present study, we investigated whether or not activins are expressed in the duct where beta-cell neogenesis is initiated. mRNA for the beta(A)- and beta(B)-subunits was expressed in isolated mouse pancreatic ducts. Immunohistochemically, the beta(A)-subunit was detected in the pancreatic duct and colocalized with cytokeratin, a marker of ductal cells. The beta(A)-subunit was also expressed in nestin-positive cells in the duct. Likewise, the beta(B)-subunit was detected in the pancreatic duct. In addition, mRNA for the type II and type IIB activin receptors was expressed in the duct. Expression of mRNA for two activin subunits was markedly increased after streptozotocin injection. Similarly, the mRNA expression was up-regulated after partial pancreatectomy. These results indicate that activins are expressed in the pancreatic duct and are up-regulated shortly after the reduction of the beta-cell mass. Induction of activins in the duct may be a critical step in the initiation of beta-cell neogenesis.

Activin Receptors↗

PubMed2002

Noninvasive differentiation of normal from pseudonormal/restrictive mitral flow using TEI index combining systolic and diastolic function.

Differentiation of normal from pseudonorma/restrictive mitral flow is not necessarily easy. Pseudonormal/restrictive flow is usually associated with left ventricular (LV) dysfunction, which can be detected using the TEI index, combining systolic and diastolic function. The purpose of this study was to test the feasibility of using the TEI index to differentiate pseudonormal/restrictive from normal mitral flow. In 33 patients with mitral flow E/A > or = 1 and LV mid-diastolic pressure measured by catheterization, the LV volumes, mitral E and A velocity, deceleration time of the E velocity, and the TEI index, defined as the sum of the isovolumic contraction and relaxation time divided by ejection time, were evaluated using Doppler echocardiography. Pseudonormal/restrictive mitral flow was defined as mitral flow E/A > or = 1 associated with LV mid-diastolic pressure > 12 mmHg. There were 22 and 11 patients with normal and pseudonorma/restrictive mitral flow, respectively. Among the indices of LV function, the TEI index achieved the best correlation with LV mid-diastolic pressures (r2 = 0.63, p < 0.0001). By setting the TEI index > or = 0.65 as the criteria for pseudonormal/restrictive mitral flow, this diagnosis had sensitivity, specificity, and accuracy of 82%, 96%, and 91%, respectively. TEI index allows noninvasive differentiation of pseudonormal /restrictive from normal mitral flow.

Aged↗

PubMed2002

Impact of atrial fibrillation on tricuspid and mitral annular dilatation and valvular regurgitation.

To investigate the effects of atrial fibrillation (AF) on the mitral and tricuspid valves, the corresponding annular dilatation and valvular regurgitation were compared with 2-dimensional and Doppler echocardiography in 31 consecutive patients with lone AF and 28 normal controls. Mid-systolic mitral and tricuspid annular areas were measured from 2 diameters in 2 orthogonal apical echocardiograms. Percent (%) mitral regurgitant (MR) or tricuspid regurgitant (TR) jet area to the left or right atrial area was evaluated and % MR or TR jet area >20% was considered moderate or significant. Both the mitral and tricuspid annular areas in patients with lone AF were significantly larger compared with the controls (mitral: 9.5 +/- 1.2 vs 6.6 +/- 0.9 cm2, lone AF vs control, p < 0.01) (tricuspid: 12.0 +/- 2.0 vs 7.5 +/- 0.9 cm2, p < 0.01). The % increase in the annular area relative to the mean normal value was significantly greater in the tricuspid valve (44 +/- 18 vs 60 +/- 28%, p < 0.01). Moderate or severe MR was not observed and the incidence of moderate or severe valve regurgitation (% jet area >20%) was significantly higher in the tricuspid valve (0/31 vs 11/31, MR vs TR, p < 0.01) in patients with lone AF. The % TR jet area showed significant correlation with tricuspid annular area (r2 = 0.65, p < 0.001). Lone AF is associated with annular dilatation of both mitral and tricuspid valves, but the annular dilatation and valvular regurgitation are significantly greater in the tricuspid valve.

Aged↗

PubMed2002

Identification of three sulfate-conjugated metabolites of berberine chloride in healthy volunteers' urine after oral administration.

AIM: To identify the structure of unknown metabolites of berberine (Ber) in human urine after oral administration. METHODS: Urine samples were obtained from 5 volunteers after they orally took Ber chloride 0.9 g per day for three days. Metabolites in urine samples were isolated and purified by polyporous resin column chromatography. The individual metabolites were identified mainly using electrospray ionization mass spectroscopy (ESI-MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy. RESULTS: Three unknown metabolites (M1, M2, and M3) were isolated. They were susceptible to arylsufatase. ESI-MS measurements of M1, M2, and M3 produced quasimolecular ions [M+H]+, m/z 17.9, 404.0, and 402.0 respectively. Especially, each of them produced a characteristic protonated ion [M-80+H]+, which can be ascribed as quasimolecular ions lost a SO3 fragment. 1H NMR spectra of the metabolites were also obtained and each of 1H signals was assigned. CONCLUSION: Structures of M1, M2, and M3 were firmly identified as jatrorrhizine-3-sulfate, demethyleneberberine-2-sulfate, and thalifendine-10-sulfate, and the major metabolite was M2.

Adult↗

PubMed2002

[Na+/H+ antiporter and plant salt tolerance].

Na+/H+ antiporter plays an important role in mechanisms of the plant salt tolerance, it extrudes Na+ from cell energized by the proton gradient generated by the plasm membrane H(+)-ATPase and/or compartmentalizes Na+ in vacuole energized by the proton gradient generated by the vacuolar membrane H(+)-ATPase and H(+)-PPiase. This review mainly discusses the latest progress in the study of Na+/H+ antiporter in plant and yeast at molecular level.

Phylogeny↗

PubMed2002

[Hairy-root culture of Polygonium multiflorum Thunb. and the production of its active constituents-anthraquinones].

Transformed hairy roots of Polygonium multiflorum Thunb. were obtained by the transformation of Agrobacterium rhizogenes LBA9402. It was clearly demonstrated that T-DNA of A. Rhizogenes Ri plasmid was integrated into the cells of hairy roots by the experiments of PCR and Southern hybridization. Through the screen of basic medium and the research of growth curve of hairy roots, the optimum inoculum time was selected in 30 days or so in the optimum condition-MS medium. On the condition, the content of rhein was 2.85 folds higher in hairy roots than that of natural plants by means of HPLC.

Anthraquinones↗

PubMed2002

[Reconstruction of partial nose defects with retroauricular free flap transplantation].

OBJECTIVE: To present the operation for nose defect reconstruction using a retroauricular free flap and the auricle cartilage. METHODS: Based on the anatomy and blood supply of the retroauricular region, a flap was designed and harvested with the posterior auricular vessels as its pedicle. The flap was used to repair nose defects in five patients. Of them, three had unilateral subtotal alinasal defects, one had nasal apex defect, and one had defects on nasal apex and bilateral ala. The size of the defect ranged from 2.5 cm x 1.5 cm to 3.0 cm x 4.0 cm. The flap varied between 3.0 cm x 2.0 cm and 4.5 cm x 3.5 cm. In 4 cases, the auricular cartilage of 2.0 cm x 1.5 cm to 1.5 cm x 1.0 cm was taken along with the flap. The posterior auricular vessels were anastomosed with the facial vessels. The donor site was covered with full-thickness skin graft. RESULTS: Postoperatively, the blood supply to the flaps was fairly good in 3 cases, while there was various venous stasis in 2 cases during the first 4 days. However, the postoperative results of the 5 cases were satisfactory. CONCLUSIONS: The retroauricular free flap is a good choice for partial nose reconstruction, which had the merits of well-hidden donor site, good color match, and one-stage operation.

Humans↗

PubMed2002

[Surgical therapy of lumbar disk herniation in 6 815 cases].

OBJECTIVE: To explore the surgical therapy for lumbar disc herniation (LDH). METHODS: Under local anesthesia by blocking the posterior branches of spinal nerves, 3 surgical approaches were adopted in 6 815 LDH cases, namely discectomy by lateral and interlamina access, double fenestration and enhanced decompression for broad central LDH, and removal of nucleus pulposus with small incision and fenestration. RESULTS: Follow-up study was conducted in 5 324 cases for the duration varying from 6 months to 14 years, averaging 6.3 years. Excellent results were achieved in 4 260 cases (80.02%), good in 855 cases (16.06%) with another 209 cases (3.92%) showing symptomatic improvement. X-ray examination in these cases revealed narrowed intervertebral spaces of different degrees without lumbar instability or spondylolisthesis. CONCLUSION: In comparison with conventional approaches, the 3 surgical approaches for LDH management may preserve the utmost integrity of the posterior lumbar structures and cause less traumatic injuries with shortened operation time and quick recovery.

Adolescent↗

PubMed2002

[Construction and growth properties of recombinant pseudorabies virus expressing modified enhanced green fluorescent protein].

The 1.0 kb DNA fragment containing the modified enhanced green fluorescent protein CDNA M1 (EGFP S147/P) and SV40 poly(A) signal sequence w as amplified and cloned in frame behind the first eight codons of the nonessential glycoprotein G (gG) of pseudorabies virus (PRV) to yield a transfer plasmid. The transfer plasmid was linearized and cotransfected with the genomic DNA of P RV Ea mutant gG(-)/LacZ(+). The resulting recombinant virus expressing M1, designated as gG(-)/LacZ(+), was isolated and confirmed by plaque purification, PCR, Southern blot and Western blot. PK-15 cells were infected with the purified recombinant virus at 0.1 pfu/cell and fluorescence emission was monitored at different times post-infection (p.i.) using fluorescence microscopy. Fluorescence emission could be detected as early as 6 h p.i. when there was no apparent cytopathic effects (CPE) yet. Fluorescence intensity increased drastically later. Maximum intensity was achieved at 24-36 h p.i. and fluorescence was stable. With the progress of the CPE, fluorescence vanished. The growth properties of gG(-)/M1(+) in tissue cultures were further examined and the titer of gG(-)/M1(+) was similar to that of PRV Ea wild strain and the parental strain gG(-)/LacZ(+). The above results indicated that the recombinant virus expressing the modified EGFP can be used as an in vivo marker to monitor replication and spread, as well as t o study the molecular pathogenesis of PRV.

Animals↗