Search PubMed⌕ Search

Biomedical subjects

T Zhang

Publications and source records attributed to T Zhang.

At least 289 records · Page 16Linked to original sources
PubMed1997

[Glomeruli manifestation of hepatitis C virus infection].

The purpose of this study was to explore the relationship between hepatitis C virus (HCV) infection and glomerulonephritis. Renal autopsy tissues taken from 21 patients with HCV infection were examined by immunohistochemical technique (S-P assay) with monoclonal anti-HCV NS3 and anti-HCV NS5. Results showed that HCAg positivity were detected in 13 out of 21 renal tissues (61.9%). 11 and 1 out of 13 were identified as membranoproliferative glomerulonephritis (MPGN) and mesangial proliferative glomerulonephritis (MsPGN) respectively, and another 1 case did not show obvious lesion. 8 out of 21 cases were negative for HCAg, in which MsPGN and membranous glomerulonephritis (MN) as well as postinfectious glomerulonephritis (PSGN) were identified in 2 and each in 1 case, respectively, except another 4 cases with no obvious lesion. The renal lesion were more common and diverse in HCV associated glomerulonephritis than hepatitis B virus (HBV) associated glomerulonephritis, the show of clinical data were similar between the two. There was HCV related glomerulonephritis and the clinical manifestation may present relevantly.

Female↗
PubMed1997

[Coxsackievirus B3-induction of tumor necrosis factor and IL-6 of murine monocyte-macrophages].

This study is to observe the infection of coxsackievirus B3 (Cox B3) to murine monocyte-macrophages (Mo/Mpsi), and its induction of tumor necrosis factor (TNF) and IL-6. Cox B3 was capable of infecting murine macrophages as revealed by immunofluorescence and releasing infectious virus particles. Virus infection with < or = 100 TCID50 did not reduce macrophages viability. Cox B3 stimulated the release of monokines from Mo/Mpsi in vitro and in vivo, markedly increasing the concentration of TNF and IL-6. These were found in the plasma and homogenized heart tissue during the acute phase of murine myocarditis induced by Cox B3, and in the culture supernatant of Mo/Mpsi infected by Cox B3.

Animals↗
PubMed1997

[Preliminary study on the arsenic trioxide-induced NB4 cell apoptosis and its molecular mechanisms].

OBJECTIVE: To illustrate the possible cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: APL cell line NB4 was used for in vitro studies. The effect of As2O3 on APL was studied by using flow cytometry, DNA electrophoresis, Narthern blotting and Western blotting. RESULTS: As2O3 induced NB4 cell apoptosis, while not inhibiting the growth and survival of two other leukemic cell lines (HL-60 and U937). Furthermore, As2O3 effectively down-regulated the expression of bcl-2 gene without changing the mRNA levels of other apoptosis-associated genes (including p53, c-myc, bax and bcl-XL). CONCLUSION: These might be one of the molecular mechanisms of As2O3 induced NB4 cell apoptosis.

Animals↗
PubMed1997

[Effects of SAD on cytogenetics of mouse embryonic cells and its embryo development].

We report here that SAD may not only suppress transcription activity of rRNA genes, but also increase SCE frequency of mouse embryonic cells, leading to bloching of the embryo development and fetal death, and finally significant decrease of birth percentage of the new born offsprings. Ata concentration of SAD in 10(-5)mol/L, the transcription activity of rRNA genes was decreased to 15% of the normal level, and the SCE frequency was increased doubly, leading to that the birth percentage was decreased to 50% of normal one. When SAD concentration of 10(-3)mol/L was used the transcription activity of rRNA genes was completely suppressed and SCE frequency was increased to as 4.8 times high as normal, leading to that the birth percentage dropped to 4% from 100%. Our results indicates that both the cytogenetic effects and the inhibition of the embryonic cells are directly proportional to the SAD concentration used. The relationship between the change of both the rRNA gene transcription and SCE frequency and the degree of embryo development are also discussed preliminarily.

Aldehydes↗
PubMed1997

[Geographic distribution of medical supplies and the numbers of hospital inpatients in the secondary medical areas in Japan].

A secondary medical area is defined as a medical administrative area under the Medical Care Law by which every prefectural government is expected to provide general medical care supplies such as beds for inpatients. This study evaluated the distribution in medical supplies among the secondary medical areas in Japan and the correlation between medical supply and demand. The numbers of hospital inpatients (residence of patients), physicians, and general beds excluding those for mental disorders and tuberculosis were analysed in relation to the population in all secondary medical areas in Japan. Those data were obtained from surveys conducted by the Ministry of Health and Welfare. The main results were as follows; 1) The distribution of physicians and general hospital beds among the secondary medical areas was not equal. 2) Even adjusted for the sex and age distribution, the highest hospital inpatients/population ratio among the secondary medical areas was four times as large as that of the lowest. 3) With multiple regression models, two independent variables (normal hospital beds/population ratio and aged 65 and over/total population ratio) accounted about 60% of the variance in hospital inpatients/population ratio. 4) The differences in medical supplies among the secondary medical areas may cause the differences in hospital inpatients/population ratio.

Age Factors↗
PubMed1997

Neuromagnetic focusing for selective transcranial stimulation of muscles.

A focusing method for spatially selective, fast and efficient neuromagnetic stimulation is described that is using novel excentric coil systems. Electrolytic tank phantoms indicate good subcutaneous focusing without surface stimulation at cutaneous and shallow subcutaneous levels. Preliminary in vivo tests in humans indicate that selective transcranial stimulation of such closely adjoining muscle group areas as the ones of the musculus abductor pollicis brevis (thumb) and the musculus interosseous I (index finger) is possible with at least 50% less power than with conventional systems, with higher repetition rates and with limited electronic tuning of the subcutaneous focusing depth. Use of this method might lead to new applications in neurology and rehabilitation medicine.

Electromagnetic Phenomena↗
PubMed1997

[Clinical studies of surgical methods for lobar and segmental bile ducts of the right liver].

OBJECTIVE: To Study the operative approach and the method of exposure and cutting open for every lobar and segmental bile ducts and solve the surgical treatment of the complex multiple stones complicated with bile ducts stenosis in the right liver. METHODS: Liver specimens of 30 adults were dissected to explore the lobar and segmental bile ducts and vessels. The exposure and cutting open of right intrahepatic bile ducts were well from the diaphragmatic face of the right hepatic lobe. This method was used in 10 patients with the disease. RESULTS: All the patients were succesfully treated. Follow-up for 3-36 months, showed that 80% patients had excelent results, and 20% good ones. CONCLUSION: The exposure and cutting open of the intrahepatic bile ducts from the diaphragmatic face of the right liver may take stones and solve bile duct stenosis in the every lobes and segment of the right liver.

Adult↗
PubMed1996

Genetic alterations on chromosomes 3 and 9 of esophageal cancer tissues from China.

In previous studies, we had demonstrated that allelic losses in esophageal cancer (EC) tissues are frequently involved in chromosomes 3 and 9 and that EC patients and their blood relatives have low capacity to repair damaged DNA and showed genetic instability. To better define the deleted chromosomal loci and understand the genetic instability in EC tissues, we selected 12 microsatellite markers (D3S1232, D3S1238, D3S1289, D3S1480, D3S647, D3S966, D3S1317, D3S659, D9S156, D9S171, D9S176 and GSN) to examine 36 paired EC tissues for loss of heterozygosity (LOH) and microsatellite instability (MIN) on chromosomes 3 and 9. The frequent LOH was found at D9S156(9p21), D3S647(3p23) and D3S1480(3p14.2), implying the possible existence of tumor suppressor genes near the deleted loci. Higher LOH incidence at D9S156 (9/18) and D3S1480 (8/19) was observed in EC tissues from Beijing, a low EC area. More frequent LOH at D3S647 (6/14) was found in EC tissues from Yangquan, a high EC area. This geographic difference of LOH occurrence was indicative of genetic heterogeneity in the etiology of EC. 24 of 36 (66.7%) EC tissues showed MIN at one or more chromosomal loci. The putative EC suppressor genes on chromosomes 3 and 9 and the molecular basis of the genetic instability associated with EC remain to be elucidated.

Alleles↗
PubMed1996

Computational method for relative binding energies of enzyme-substrate complexes.

A computational method for estimating the relative binding free energies of enzyme-substrate complexes is described that combines electrostatic and solvation models and X-ray crystallographic data. The polar contribution is evaluated by the Poisson-Boltzman equation. The nonpolar contribution is evaluated by solvent transfer data and surface area calculations. This algorithm was used to calculate the relative binding energies of 63 pairs of nine different mutant proteins with seven different substituted R-malate substrates of Escherichia coli isocitrate dehydrogenase. Comparison of calculated values with the experimentally observed values shows a high degree of correlation.

Algorithms↗
PubMed1996

Influenza infection in humans and pigs in southeastern China.

The three last pandemic strains of influenza A virus-Asian/57, Hong Kong/68 and Russian/77-are believed to have originated in China. The strains responsible for the 1957 and 1968 human pandemics were reassortants incorporating both human and avian influenza viruses, which may have arisen in pigs. We therefore undertook a population-based study in the Nanchang region of Central China to establish the prevalence, types and seasonal pattern of human influenza infection and to screen serum samples from animals and humans for evidence of interspecies transmission of influenza viruses. Two definite influenza seasons were demonstrated, one extending from November to March and the other July to September. The profile of antibodies to commonly circulating human influenza viruses was no different in Nanchang and neighboring rural communities than in Memphis, Tennessee, USA. In particular, Chinese women who raised pigs in their homes were no more likely to have been exposed to influenza virus than were subjects who seldom or never had contact with pigs. However, we did obtain evidence using isolated H7 protein in an enzyme-linked immunoabsorbent assay for infection of pig farmers by an avian H7 influenza virus suggesting that influenza. A viruses may have been transmitted directly from ducks to humans. The results of the serological survey also indicated that pigs in or near Nanchang were infected by human H1N1 and H3N2 influenza viruses, but not with typical swine viruses. We found no serological evidence for H2 influenza viruses in humans after 1968.

Adolescent↗
PubMed1996

Comparison of inactivation and unfolding of green crab (Scylla serrata) alkaline phosphatase during denaturation by guanidinium chloride.

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, each active site in which contains a tight cluster of two zinc ions and one magnesium ion. Unfolding and inactivation of the enzyme during denaturation in guanidinium chloride (GuHCl) solutions of different concentrations have been compared. The kinetic theory of the substrate reaction during irreversible inhibition of enzyme activity previously described by Tsou [(1988), Adv. Enzymol. Related Areas Mol. Biol. 61, 381-436] has been applied to a study on the kinetics of the course of inactivation of the enzyme during denaturation by GuHCl. The rate constants of unfolding and inactivation have been determined. The results show that inactivation occurs before noticeable conformational change can be detected. It is suggested that the active site of green crab alkaline phosphatase containing multiple metal ions is also situated in a limited region of the enzyme molecule that is more fragile to denaturants than the protein as a whole.

Alkaline Phosphatase↗
PubMed1996

Mu- and delta-opioid receptor antagonists precipitate similar withdrawal phenomena in butorphanol and morphine dependence.

The relative involvement of mu- and delta-opioid receptors in the mediation of butorphanol-, as compared to morphine-, dependence was examined with the use of highly selective antagonists at mu- and delta-opioid receptors. Extracellular fluid levels of glutamate (Glu) and aspartate (Asp) were measured within the pontine locus coeruleus following precipitation of withdrawal from dependence on either butorphanol or morphine in conscious Sprague-Dawley rats. Dependence was induced by intracerebroventricular (i.c.v.) infusion of butorphanol (26 nmol/mu l/h), morphine (26 nmol/mu l/h) or saline vehicle (1 mu l/h) for 3 days by means of an osmotic minipump. Microdialysis probes (2 mm tip) were inserted into the locus coeruleus 24 h before precipitation of withdrawal by i.c.v. injection of either the mu-opioid receptor antagonist, D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP; 48 nmol/5 mu l or 48 nmol/5 mu l), or the delta-opioid receptor antagonist, naltrindole (17-cyclopropy;methyl-6,7-dehydro-4,5-epoxy-3, 14-dihydroxy-6,7,2'3'-indolmorphinan hydrochloride; 48 nmol/5 mu l or 100 nmol/5 mu l). Baseline levels of Glu ranged from 9.59 + or - 1.27 to 12.84 + or - 3.01 mu M in the various treatment groups. Levels of Asp were similar. Precipitation of withdrawal by CTOP elicited significant increases of Glu and Asp in both morphine- and butorphanol-dependent rats. Maximal increases in Glu of 425% and 258% above baseline levels were elicited in the first 15 min microdialysis sample following i.c.v. injection of CTOP in morphine- and butorphanol-dependent rats, respectively. Behavioral signs of withdrawal were greater in morphine than butorphanol-dependent groups. The i.c.v. treatment with naltrindole elicited increases in Glu and Asp that were similar, although less marked, than those precipitated by CTOP treatment. Administration of naltrindole produced equivalent signs of withdrawal in both morphine- and butorphanol-dependent rats. Withdrawal from dependence on both morphine and butorphanol is characterized by elevations in coerulear levels of excitatory amino acids. Responses elicited following the use of selective mu- and delta-opioid receptor antagonists to precipitate withdrawal suggest that the role played by these receptors in mediation of the signs and symptoms of withdrawal do not differ greatly between butorphanol- and morphine-dependent rats.

Animals↗
PubMed1996

Comparison of inactivation and unfolding of yeast alcohol dehydrogenase during denaturation in urea solutions.

It has been reported that inactivation occurs before noticeable conformational changes can be detected during the denaturation of a number of enzymes by denaturants. Therefore, Tsou suggested that the conformation of the enzyme active sites is more easily perturbed and hence more flexible than the molecule as a whole (Tsou, Trends in Biochemical Science, 1986, 11, 427-429; Tsou, Science, 1993, 262, 380-381). In this study, inactivation and unfolding of yeast alcohol dehydrogenase containing zinc ions in urea solutions of different concentrations are compared. The results show that much lower concentrations of urea are required to bring about inactivation than significant unfolding of the enzyme molecule. At the same urea concentration, inactivation rate is much faster than that of the unfolding of the enzyme molecule as a whole. The results suggest that active sites of yeast alcohol dehydrogenase containing zinc ions also display more conformational flexibility than the enzyme molecules as a whole.

Alcohol Dehydrogenase↗
PubMed1996

Elevated cyclooxygenase-2 levels in Min mouse adenomas.

BACKGROUND & AIMS: Mutations in the APC gene result in an increased propensity to develop intestinal neoplasia; however, a complete understanding of the mechanisms resulting in tumor formation has remained elusive. Min mice possess a mutation in the APC gene and display a neoplastic phenotype similar to that observed in familial adenomatous polyposis coli in humans. Cyclooxygenase (COX) inhibitors decrease tumor multiplicity in the Min mouse intestine. The present study was designed to determine if there was an increase in COX-2 in adenomas harvested from Min mouse intestine. METHODS: COX-2 messenger RNA levels were determined by Northern blots and reverse-transcription polymerase chain reactions of B6Min x 129 mouse-derived tumors. Protein levels and localization were determined by Western blots and immunohistochemical staining. RESULTS: The Northern blots revealed an approximately threefold increase in the level of COX-2 messenger RNA in Min mouse adenoma compared with normal mucosa. COX-2 protein levels in adenomatous tissues were also approximately threefold higher compared with normal mucosa from the same mouse. Immunohistochemical staining with a monospecific COX-2 antibody confirmed that increases in COX-2 immunoreactivity were restricted to dysplastic and neoplastic foci within intestinal mucosa. CONCLUSIONS: These data show that COX-2 levels may be increased at an early stage in colorectal neoplasia during polyp formation and before invasion.

Adenoma↗