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Biomedical subjects

T Zhang

Publications and source records attributed to T Zhang.

At least 307 records · Page 17Linked to original sources
PubMed1996

Rilmenidine and reflex renal sympathetic nerve activation in Wistar and hypertensive rats.

1. This study sets out to examine the effect of rilmenidine administered systemically on basal and reflexly activated renal nerve activity in Wistar and stroke prone spontaneously hypertensive rats (SHRSP). 2. Animals were anaesthetized with chloralose/urethane, stimulating electrodes were placed on the brachial plexi and the renal nerves were isolated and put on recording electrodes. Both brachial nerves were stimulated electrically at 0.8, 1.6 and 3.2 Hz (15 V, 0.2 ms) in the absence and in the presence of rilmenidine given at 100 and 200 micrograms kg-1 i.v. in a cumulative manner. 3. Stimulation of the brachial nerves caused graded increases in blood pressure, heart rate and integrated renal nerve activity (P < 0.05) in both Wistar and SHRSP. Fast Fourier transformation of the renal nerve activity signal to generate a power spectrum demonstrated that both total power and percentage power at heart rate was higher in the SHRSP than Wistar (P < 0.05). Total power was raised during brachial nerve stimulation in both Wistar and SHRSP by some 200-300% (P < 0.05) but the percentage power at heart rate was decreased by some 60% (P < 0.01) in the Wistar but was raised by some 40-50% (P < 0.05) in the SHRSP. 4. Administration of rilmenidine caused dose-related decreases in blood pressure and heart rate and integrated renal nerve activity in both Wistar and SHRSP (all P < 0.05). Both doses of rilmenidine decreased (P < 0.05) the total power in the signal in both strains of rat by about one-half but the power occurring at heart rate only fell at the higher dose of compound in the Wistar, whereas in the SHRSP it was decreased by both doses by approximately 60-70%. In the presence of rilmenidine, coherence of the renal nerve signal was reduced in the Wistar and SHRSP and although the drug had no effect on phase difference in the Wistar, this parameter was decreased in the SHRSP by the low and high doses of rilmenidine (P < 0.05). 5. In the presence of 100 micrograms kg-1 rilmenidine, stimulation of the brachial nerves caused increases in total power in the Wistar and SHRSP (two to three fold, P < 0.05), together with a decrease (P < 0.05) in the percentage power occurring at heart rate in the Wistar, of some 60%, and an increase (P < 0.01) in the SHRSP, of some two to three times, which were very similar in magnitude and pattern to those obtained in the absence of the drug. Following the 200 micrograms kg-1 dose of rilmenidine, brachial nerve stimulation increased total power in the Wistar and SHRSP groups (P < 0.05) and whereas in the Wistar the percentage power at heart rate did not change in the SHRSP it was again increased in response to the electrical stimulation of the brachial plexus (P < 0.001) by between two to three fold. 6. These results showed that in both the Wistar and SHRSP rilmenidine depressed blood pressure, heart rate and integrated renal nerve activity. Moreover, rilmenidine did not affect the reflex activation of renal nerve activity via the somatosensory system although the characteristics within the power spectra underwent certain changes which might have a functional impact at the level to the kidney.

Animals↗
PubMed1996

Oral immunization with an attenuated vaccine strain of Salmonella typhimurium expressing the serine-rich Entamoeba histolytica protein induces an antiamebic immune response and protects gerbils from amebic liver abscess.

Attenuated salmonellae represent attractive candidates for the delivery of foreign antigens by oral vaccination. In this report, we describe the high-level expression of a recombinant fusion protein containing the serine-rich Entamoeba histolytica protein (SREHP), a protective antigen derived from virulent amebae, and a bacterially derived maltose-binding protein (MBP) in an attenuated strain of Salmonella typhimurium. Mice and gerbils immunized with S. typhimurium expressing SREHP-MBP produced mucosal immunoglobulin A antiamebic antibodies and serum immunoglobulin G antiamebic antibodies. Gerbils vaccinated with S typhimurium SREHP-MBP were protected against amebic liver abscess, the most common extraintestinal complication of amebiasis. Our findings indicate that the induction of mucosal and immune responses to the amebic SREHP antigen is dependent on the level of SREHP-MBP expression in S. typhimurium and establish that oral vaccination with SREHP can produce protective immunity to invasive amebiasis.

Administration, Oral↗
PubMed1996

A unique transactivation sequence motif is found in the carboxyl-terminal domain of the single-strand-binding protein FBP.

The far-upstream element-binding protein (FBP) is one of several recently described factors which bind to a single strand of DNA in the 5' region of the c-myc gene. Although cotransfection of FBP increases expression from a far-upstream element-bearing c-myc promoter reporter, the mechanism of this stimulation is heretofore unknown. Can a single-strand-binding protein function as a classical transactivator, or are these proteins restricted to stabilizing or altering the conformation of DNA in an architectural role? Using chimeric GAL4-FBP fusion proteins we have shown that the carboxyl-terminal region (residues 448 to 644) is a potent transcriptional activation domain. This region contains three copies of a unique amino acid sequence motif containing tyrosine diads. Analysis of deletion mutants demonstrated that a single tyrosine motif alone (residues 609 to 644) was capable of activating transcription. The activation property of the C-terminal domain is repressed by the N-terminal 107 amino acids of FBP. These results show that FBP contains a transactivation domain which can function alone, suggesting that FBP contributes directly to c-myc transcription while bound to a single-strand site. Furthermore, activation is mediated by a new motif which can be negatively regulated by a repression domain of FBP.

Amino Acid Sequence↗
PubMed1996

Protection against amebic liver abscess formation in the severe combined immunodeficient mouse by human anti-amebic antibodies.

We have used serum from patients with amebic liver abscess to investigate the role of antibody in the prevention of invasive amebiasis using the severe combined immunodeficient (SCID) mouse model of Entamoeba histolytica infection. The SCID mice were passively immunized with serum or purified antibody from patients with amebic liver abscess 24 hr prior to the direct intrahepatic challenge with 10(6) virulent E. histolytica trophozoites. This treatment reduced the mean abscess size in these animals from 24.5% to 3.5% (P < 0.0001). These results demonstrate that human anti-amebic antibodies are capable of exerting a protective effect in an animal model of amebic liver abscess formation.

Animals↗
PubMed1996

Masking Patterns for Partially Masked Tinnitus.

Tinnitus isomasking contours were determined for unmasked tinnitus and for tinnitus partially masked by high-pass noise. The noise was selected so that it masked all but the low frequency components of the tinnitus. As a control, the masking pattern of an external tone in the tinnitus region and in the presence of the high-pass noise was compared with that of the partially masked tinnitus. Frequency-specific masking was obtained for the external tone but not for the partially masked tinnitus. This suggests that even narrowband tinnitus is not masked in the cochlea. Thus, tinnitus maskers need not include the frequency region presumed to contain the tinnitus.

Journal Article↗
PubMed1996

[A serological study on the infection of Helicobacter pylori among children].

Using ELISA method, anti-H. pylori IgG and IgM were detected in 181 sera from patients (aged 2-14 years) complaining of repeated midepigastical pain and 152 sera of controls. The positive rate of anti-H, pylori IgG in the patients was 53%, significantly higher than those of control groups (34.6%-35%), (P < 0.05). The presence of anti-H. pylori IgG in serum can assist in the diagnosis of H. pylori, but can not indicate the existence of H. pylori. There were no evident relationships between level of antibodies (anti-H. pylori IgG and IgM) and the degree of H. pylori infection, or the duration of disease. Children's H. pylori infection increases with age. Elder children have the same positive rate of anti-H. pylori IgG as adults. Hence, eradication of H. pylori infection should be focused not only on adults but also on children.

Adolescent↗
PubMed1996

Adenovirus-mediated in vivo gene transfer in a rabbit model of allograft vasculopathy.

BACKGROUND: The long-term success of heart transplantation continues to be in jeopardy because of the development of accelerated vascular myointimal proliferation. Transfer of genes encoding products that can modulate the adverse consequences of phenomena that cause myointimal proliferation, into the allograft vessel wall, may modify these pathologic processes. The purpose of this study was to assess the feasibility of gene transfer and to evaluate the duration of gene expression in a rabbit heterotopic aortic transplant model of allograft vasculopathy. METHODS: The abdominal aortas of 32 outbred New Zealand rabbits were harvested and cross-sectionally bisected (n = 64). Six donor and recipient animals were used in a preliminary study to examine neointimal proliferation without accompanying gene transfer. Of the remaining 26 rabbits (52 allografts), one half of each allograft aorta was administered a control solution, while the other half was incubated with a replication-defective, recombinant, adenoviral vector-encoding, cytomegalovirus promoter-regulated beta-galactosidase. After a 20-minute incubation period, bilateral aorto-carotid transplantations were performed in 26 recipient rabbits. All animals received cyclosporine immunosuppression (10 mg/kg/day subcutaneously). The allografts were harvested at 3, 7, 10, 21, and 28 days after transplantation and assayed for beta-galactosidase activity. RESULTS: Neointimal areas showed an initially slow increase for the first 10 days, followed by a rapid increase up to 21 days, and tended to plateau thereafter. Significant beta-galactosidase was apparent in aortic sections dissected from host rabbits for all time points, except at 28 days. At the 21-day time point, the aortic section from one rabbit was positive, whereas the other two remained negative. However, the one positive section showed intense beta-galactosidase activity, suggesting variability in the experimental model. At 28 days, all aortic sections were negative. CONCLUSIONS: Our findings confirm that genes delivered by this method are expressed for the duration of early rapid intimal proliferation in this heterotopic rabbit model of aortic allograft vasculopathy. These findings suggest that this animal model can be used to assess the therapeutic potential of gene transfer at the time of vascular transplantation and may provide a novel therapeutic approach to prevent or ameliorate the genesis of allograft vasculopathy.

Adenoviruses, Human↗
PubMed1996

[The imaging features of multiple endocrine neoplasia].

The article describes ultrasonographic (US), computed tomographic (CT), 99mTc-MIBI and angiographic findings of 16 cases of multiple endocrine neoplasia (MEN) confirmed by operations and pathological examinations. Hyperparathyroidism either was the first manifestation of MEN I or was diagnosed simultaneously with other tumors. Medullary thyroid carcinoma usually developed first or coincided with pheochromocytoma in MEN I. Regular US and CT screening can lead to the detection of new endocrine neoplasia. The authors consider that US and CT are the best imaging methods for MEN.

Adenoma↗
PubMed1996

Inhibition of spontaneous apoptosis in human breast cancer.

Breast tumorigenesis proceeds through an accumulation of specific genetic alteration. Breast malignant transformation is dependent on not only the rate of cell production but also on apoptosis, a genetically programed process of autonomous cell death. We investigated whether breast tumorigenesis involved an altered susceptibility to apoptosis and proliferation by examining normal breast epithelium and breast cancer samples. We found there is a great inhibition of spontaneous apoptosis in breast cancer cells compared with normal breast epithelium. The inhibition of apoptosis in breast cancer may contribute to neoplastic transformation.

Apoptosis↗
PubMed1996

[A seroepidemic survey on the infection of toxoplasma in pregnant women and its significance to better child-bearing].

In order to find out the perniciousness of Toxo infection in pregnant women and to adopt proper intervention measures, we carried out a seroepidemiologic survey of Anti-Toxo-IgM with Capture-EIA in pregnant women who were given perintal medical care in Henan province. The positive rate of Anti Toxo-IgM was 3.38% among 4,126 pregnant women. A follow-up survey showed that abnormal birth rate was 8.20% in those infected women. We tried intervention at birth in six infected women including four on an initiative termination of pregnancy. Among the two who insisted in heeping pregnant, one neonate died of unusual delivery. Based on the study findings, sero-epidemiologic survey in pregnant women shows an important significance in better child-bearing.

Adult↗
PubMed1996

[Smooth muscle neoplasms of the uterus--a 51 cases study].

To discuss the diagnosis of uterine leiomyosarcoma and leiomyoma of cellular and bizarre type, we reviewed 51 cases and carried out P53 and desmin immunohistochemical staining on 43 cases. We found that in most cases leiomyosarcoma is accompanied by nuclear mitosis, cell atypia and margin infiltration. In a small number of cases, though mitotic figures are scarce, high cell atypia and marked margin infiltration were present. Leiomyoma variants may have high cellular density and bizarre nuclears but have no margin infiltration. Leiomyosarcoma has a high incidence of P53 expression, while no P53 expression was detected in leiomyoma variants. Desmin expression is closely correlated with the differentiation of smooth muscle neoplasms of the uterus. We conclude that nuclear mitotic activity is an important but not independent criteria in the diagnosis of uterine leiomyosarcoma. Cellular atypia and margin infiltration should be considered. P53 and desmin expression can be applied as accessary criteria.

Adult↗
PubMed1996

[Improvement of coronary flow by artificial decending the intrathoracic pressure].

In simulating the changes of intrathoracic pressure during deep inhalation, the intrathoracic pressure was descended by repeated aspiration from thoracic cavity in 8 dogs. The volume of coronary flow was observed simultaneously. It was found that when intrathoracic pressure was dropping the coronary flow volume showed an increase as a result of decrease of right atrium pressure and increase of aorta pressure, thus creating an increased pressure difference between inflow and outflow of coronary circulation.

Animals↗