Biomedical subjects

Z S Zhang

Publications and source records attributed to Z S Zhang.

13 recordsLinked to original sources

PubMed1992

Hepatitis B virus X protein is not central to the viral life cycle in vitro.

The hepatitis B x (HBx) gene is the smallest open reading frame of the hepatitis B virus (HBV) genome. It is conserved among all mammalian hepadnaviruses and is expressed during viral infection. While the HBx protein (pX) has been shown to trans-activate the transcription of a wide range of viral and cellular genes and to induce liver cancer in transgenic mice, the significance of pX for the life cycle of HBV itself has not been elucidated. To assess the function of pX in viral replication and virion export, we designed an X-minus mutant by introduction of a stop codon at the beginning of the HBx gene without affecting the viral polymerase gene product. Transient transfection analyses using different cell lines revealed that this X-minus mutant directs the synthesis of wild-type levels of viral proteins, replicative intermediates, and virion export. These data suggest that the expression of the highly conserved HBx gene is not central for the life cycle of HBV in vitro but may be involved in the pathogenicity of hepadnavirus infection, including liver cancer development.

Base Sequence↗

PubMed1992

Detection of human papillomavirus DNA sequences in cervical lesions by in situ hybridization using biotinylated DNA probes.

Ninety-six biopsy specimens were collected for studying the association of specific sequences of HPV DNA with genital warts, precancerous lesions and invasive cervical cancer. Using DNA probes labeled with biotin, 17 of the 22 (77.27%) specimens showing condyloma and 1 of the 14 (7.14%) specimens displaying subclinical papillomavirus infection (SPI) of cervix were found to be positive for HPV 6/11; 4 of 23 (17.39%) specimens of squamous epithelial cervical cancer and 2 of the 23 (8.70%) specimens of cervical intraepithelial neoplasia (CIN) were positive for HPV 16/18. All the 14 specimens of cervicitis were negative for both probes. The HPV 6/11 positive hybridization products were present mainly in the superficial and intermediate epithelium of condyloma and SPI. In invasive cancer, HPV 16/18 were shown more often in cancer cells of infiltrative nests and were focally distributed.

Biopsy↗

PubMed1991

Serotoninergic varicosities make synaptic contacts with pleural sensory neurons of Aplysia.

Serotonin is a modulatory neurotransmitter that produces many of the cellular changes associated with sensitization of reflexes in Aplysia. These changes have been carefully documented in sensory neurons located in the abdominal ganglion that mediate the gill-siphon withdrawal reflex and in sensory neurons located in the pleural ganglion that mediate the tail-siphon withdrawal reflex. Although serotonin appears to be necessary for sensitization, there is no direct evidence that serotoninergic neurons make synaptic contacts with sensory neurons. In this study, the immunoperoxidase technique was used to label serotonin-immunoreactive neurites surrounding the cell bodies of sensory neurons in the pleural ganglion. Serotonin-immunoreactive neurites had varicosities whose mean short axis diameter was 1.1 +/- 0.6 microns (mean +/- S.D.). The shape of the size distribution was skewed toward larger sizes, however, suggesting that there were multiple subpopulations of varicosities. One subpopulation was that of varicosities located at branch points whose average short axis diameter was larger than normal (1.7 +/- 0.5 microns). Serotonin-immunoreactive varicosities were directly apposed to the sensory neurons without intervening glial cells. In most contacts, serotonin-immunoreactive neurites invaginated into the plasma membranes of the sensory neurons. There were also a few contacts onto spinelike processes, but these were flat rather than invaginated. Serotoninergic neurons whose activity produces changes in the electrophysiological properties of sensory neurons have been identified, but this study provides the first direct evidence for synaptic connections between serotoninergic neurons and sensory neurons in Aplysia.

Animals↗

PubMed1991

[Detection of Plasmodium falciparum infection in humans by (Dig)-DNA probe].

In this study, we used Digoxigenin, (Dig)-11-dUTP, in the Genius kit purchased from Boehringer Mannheim to label the Plasmodium falciparum (P.f.) DNA fragment by random primed labelling method. The P. falciparum DNA fragment was isolated from the recombinant clone pPF14 by enzyme digestion and agarose electrophoresis. This probe is designated pPF14-F-Dig. Purified P.f. DNA and blood samples from malaria patients in Hainan Province of China were detected by the probe in dot-blot hybridization. Thirty-eight patients with falciparum malaria, three with falciparum malaria and vivax malaria and four with vivax malaria were detected with the pPF14-F-Dig probe. The results showed that the pPF14-F-Dig probe could detect at least 40 pg of P.f. DNA and a parasitemia of 0.005 percent. Out of 38 detected P.f. patients' blood samples, 33 hybridized positively with this probe. The positivity rate was 86.8%. Twenty-one normal blood samples all showed negative. In addition, 2 of 3 samples with P.f. and P.v. were positive. Three of 4 samples with P.v. were negative and one was doubtful. The preliminary result of this study indicates that the pPF14-F-Dig probe could detect the patients of falciparum malaria with good sensitivity and specificity, and that this probe can be used to detect the patients with P. falciparum in Hainan Province.

Animals↗

PubMed1990

Recombinant bivalent live vaccines against neonatal colibacillosis in piglets.

The genes of colonization factor K88 and avirulent heat-labile enterotoxin LT A-B+ of enterotoxigenic E. coli (ETEC) have been ligated, and a vaccine strain containing recombinant plasmid that efficiently expresses two antigens has been obtained. Using the activity of beta-galactosidase as a selection marker instead of drug resistance, another bivalent vaccine strain with the same expression level has also been constructed. The vaccine strains have no toxicity and do not cause any adverse reactions. In challenge study and field trials, a high degree of protection from colibacillosis was afforded to piglets when their dams were immunized orally or parenterally. Practice of bivalent live vaccines including colonization factor and enterotoxin antigens and without antibiotic resistance gene shows effective.

Adhesins, Escherichia coli↗

PubMed1989

[Abdominal cocoon].

Two cases of abdominal cocoon are reported. Abdominal cocoon is rare, only 31 cases reported in the literature. The majority of the cases are adolescent girls with symptoms of acute or chronic intestinal obstruction and/or abdominal mass. Ultrasound examination shows the mass is a shadow of intestinal loop aggregation and barium meal reveal the mass to be made of folded intestine. Operative findings showed the bowel is encased in a white, tough and dense membrane that on microscopic examination thickened fibrous tissue are found Partiac. Removal of the membrane, releasing the intestine adhesions and plication of the bowel may be effective.

Adult↗

PubMed1989

[Identification of 219 mycobacterial strains: with a report of 3 cases of pulmonary mycobacterial intracellular diseases].

Isolated mycobacterium from 219 cases of pulmonary tuberculosis was identified according to the criteria of growth in para-aminobenzoic acid medium, rough or smooth type of colony as well as easy or difficult to emulsified etc. 6 strains (2.7%) of atypical mycobacteria have been found. Among them 3 cases (1.4%) of pulmonary mycobacterial intracellular diseases were diagnosed finally. All of the 211 strains (cases) of the rough type are difficult to emulsify, but 8 strains (cases) of the smooth type are all easy to emulsify.

Aged↗

PubMed1988

Gossypol acetate-induced SCEs in spermatogonia and bone marrow cells of mice: dose-response relationships.

Gossypol acetic acid has been shown to have the effect of increasing the SCE frequencies in the spermatogonial cells of mice. This study further confirmed the genotoxic effects of gossypol acetic acid by investigating the dose-response relationships of gossypol acetic acid-induced SCEs in spermatogonial cells and bone marrow cells of mice. Twelve or over 12 mg/kg body weight of the dosage per day could increase the SCE frequencies of both bone marrow cells and spermatogonial cells. The increase of SCE frequency appeared to be directly correlated with the doses used at significant levels (p less than 0.001). Regression lines indicated that, in spite of cell type variation, the SCE induced was proportional to the dose of gossypol acetic acid.

Animals↗

PubMed1988