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Biomedical subjects

H Tao

Publications and source records attributed to H Tao.

At least 73 records · Page 4Linked to original sources
PubMed1993

Regulation of atrial natriuretic peptide receptors in vascular smooth muscle cells: role of cGMP.

We tested the hypothesis that intracellular guanosine 3',5'-cyclic monophosphate (cGMP) regulates atrial natriuretic peptide (ANP) receptors. The effect of chronic exposure to ANP, sodium nitroprusside (SNP), and 8-bromo-cGMP (8-BrcGMP) on ANP receptors and cGMP formation was determined in guinea pig thoracic aorta smooth muscle cells (TASM) and in coronary artery smooth muscle cells (CASM). TASM express both the ANP-activated guanylyl cyclase (B-receptor) and the clearance receptor (C-receptor) and respond to ANP with increased cGMP. CASM exhibit only the ANP C-receptor. In TASM, 24-h treatment with 1 microM atriopeptin (AP) III [rat ANP-(103-126)] caused a sixfold increase in basal cGMP levels, which were unaltered in CASM. In AP III-treated TASM, maximal binding of 125I-labeled AP III (Bmax) was reduced 40% while affinity [dissociation constant (KD)] was unaltered. In CASM, Bmax and KD were not affected. In treated TASM, washed free of AP III, acute dose-response curves of cGMP to AP III were not different from that in untreated cells. In both TASM and CASM, basal cGMP levels were elevated and Bmax was decreased by 6-h treatment with SNP. SNP did not alter the acute response of cGMP to AP III. In both cell types, 8-BrcGMP for 6 h caused reduction in Bmax. These findings support the conclusion that elevated cGMP was necessary for ANP-induced downregulation of receptors. The unaltered responsiveness of cGMP to AP III suggests the B-receptor was not altered and the reduced Bmax was due to decreased C-receptor.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Rhizobium leguminosarum CFN42 lipopolysaccharide antigenic changes induced by environmental conditions.

Four monoclonal antibodies were raised against the lipopolysaccharide of Rhizobium leguminosarum bv. phaseoli CFN42 grown in tryptone and yeast extract. Two of these antibodies reacted relatively weakly with the lipopolysaccharide of bacteroids of this strain isolated from bean nodules. Growth ex planta of strain CFN42 at low pH, high temperature, low phosphate, or low oxygen concentration also eliminated binding of one or both of these antibodies. Lipopolysaccharide mobility on gel electrophoresis and reaction with other monoclonal antibodies and polyclonal antiserum indicated that the antigenic changes detected by these two antibodies did not represent major changes in lipopolysaccharide structure. The antigenic changes at low pH were dependent on growth of the bacteria but were independent of nitrogen and carbon sources and the rich or minimal quality of the medium. The Sym plasmid of this strain was not required for the changes induced ex planta. Analysis of bacterial mutants inferred to have truncated O-polysaccharides indicated that part, but not all, of the lipopolysaccharide O-polysaccharide portion was required for binding of these two antibodies. In addition, this analysis suggested that O-polysaccharide structures more distal to lipid A than the epitopes themselves were required for the modifications at low pH that prevented antibody binding. Two mutants were antigenically abnormal, even though they had abundant lipopolysaccharides of apparently normal size. One of these two mutants was constitutively unreactive toward three of the antibodies but indistinguishable from the wild type in symbiotic behavior. The other, whose bacteroids retained an epitope normally greatly diminished in bacteroids, was somewhat impaired in nodulation frequency and nodule development.

Antibodies, Bacterial↗
PubMed1992

[Enhancement of bleomycin or hyperthermia induced tumor cell damage by ADPRT inhibitor].

Enhancement of tumor cell damage by ADPRT inhibitor, 3-aminobenzamide (3AB) was investigated. 3AB could inhibit DNA strand break repair in HeLa S3 cells after treatment with bleomycin. 3AB was able to lower the clonogenic ability of HeLa S3 cells after bleomycin treatment and hyperthermia. 3AB could also prevent potentially lethal damage repair (PLDR) in HeLa S3 cells treated with bleomycin. This work presents some experimental evidence and theoretical background for the possible use of 3AB as a sensitizer in the treatment of cancer.

Benzamides↗
PubMed1991

Expression of the major inner capsid protein of the group B rotavirus ADRV: primary characterization of genome segment 5.

A complete cDNA copy of the fifth RNA segment of the human group B rotavirus, ADRV, has been cloned into plasmid AD512. Gene segment 5 contains 1269 bases and encodes one long open reading frame of 391 amino acids beginning at base 31 and terminating at base 1203. The gene 5 polypeptide, expressed in vitro in a rabbit reticulocyte lysate, comigrates with the 44-kDa major inner capsid protein present on EDTA treated ADRV virions. The gene 5 protein is immunoprecipitable by hyperimmune serum to ADRV, human ADRV convalescent serum and by a group B-specific monoclonal antibody. In addition, this protein shares amino acid identity and similarity with the VP6 proteins from group C and group A rotavirus strains. The ADRV VP6 equivalent protein appears to be more closely related to the group C VP6 than the Group A VP6 polypeptide and a common ancestral rotavirus VP6 precursor protein is suggested. As a result, the fifth RNA segment of ADRV defines the major inner capsid protein, or VP6 equivalent, in the group B rotavirus. Expression of the ADRV VP6 equivalent protein is potentially useful for evaluating the prevalence of serum antibodies to group B rotavirus in human and animal populations as well as for generating antibodies for the direct detection of group B rotavirus antigen.

Amino Acid Sequence↗
PubMed1991

Small-bowel carcinoid presenting in association with a phytobezoar.

An unusual case of a recurrent, postoperative, small-bowel obstruction is presented. The obstruction was due to a phytobezoar proximal to the site of a primary carcinoid of the small bowel. The radiologic findings of a mobile, intraluminal filling defect and a more distal, fixed mural mass are reviewed. The cause of the recurrent obstruction was likely a "ball-valve" effect of the phytobezoar at the site of stenosis caused by the carcinoid. This case emphasizes the value of small-bowel imaging in repeated small-bowel obstruction.

Bezoars↗
PubMed1990

[Synthesis of zinc chlorophyllin a and its preliminary clinical application].

A method for synthesis of zinc chlorophyllin a (I), a promising drug for clinical application, is presented. Taking silkworm faeces as a raw material. Chlorophyll was extracted with ethyl alcohol. After concentration the solid formed was dissolved in petroleum ether and the solution was subjected to column chromatography to separate pheophytin a and chlorophyll a. The products were dissolved in ethyl ether and the Mg in the products was stripped off with concentrated hydrochloric acid. The excess hydrochloric acid in the solution was neutralized with ammonia solution and the mixture was hydrolyzed with diluted hydrochloric acid to obtain pheophorbide a, then (I) was synthesized with pheophorbide a and zinc salt. The characteristics of (I) and pheophorbide a were checked by IR, UV and elemental analyses. All results of pheophorbide a coincided with those values reported in literature. The acute toxicity of (I) was tested in mice and the LD50 of (I) was 324 +/- 40 mg/kg. (I) has been applied in several hospitals for several months. It has been found that (I) has outstanding effects on burns and oral sepsis and that it increases the growth of granulation tissue and epithelium remarkably.

Animals↗
PubMed1990

[Synthesis and animal experiments of ethylnitrosourea].

Ethylnitrosourea (ENU) was synthesized with raw materials such as ethylamine and sodium nitrite. The product was a yellowish powder. Its melting point, solubility and infrared absorption spectrum coincided with those reported in the literature. The result form elementary analysis for the product was almost the same as the theoretical value. The product was applied to rats by various methods. It was found that ENU was a cancerogenic compound, especially to the nervous system. More details about the animal experiments will be published in some other papers.

Animals↗
PubMed1987

Morphology and morphogenesis of viruses of hemorrhagic fever with renal syndrome. II. Inclusion bodies--ultrastructural markers of hantavirus-infected cells.

Three distinctive types of viral inclusion bodies were identified in hantavirus-infected cells by thin-section electron microscopy. The inclusion bodies, designated granular, granulofilamentous, and filamentous, were intracytoplasmic and closely associated with the rough endoplasmic reticulum and Golgi cisternae. Virus specificity of the inclusions was verified by immune colloidal gold and immunoperoxidase labeling. The inclusion bodies were a common morphological marker for 13 strains of hantaviruses studied, irrespective of their origin.

Animals↗
PubMed1986

Antigenic characterization and ELISA detection of adult diarrhea rotaviruses.

Recently, severe epidemics of diarrhea among both adults and children in China have been associated with an agent called adult diarrhea rotavirus (ADRV). We have studied ADRV from two areas of China (Jinzhou and Guangxi) and compared them with prototype group A, B, and C rotaviruses. The viral genomes were compared by electrophoresis of the RNA genome segments in polyacrylamide gels, and the antigenic relatedness of these viruses was examined by immune electron microscopic studies using virus preparations of either double- or single-capsid particles. Hyperimmune antisera (guinea pig and rabbit) to one strain of ADRV reacted with high titers with other strains of ADRV and with single-shelled capsids of a porcine group B rotavirus. The antisera to ADRV did not react with either group A or group C rotaviruses. Antisera to either bovine or porcine group B rotaviruses reacted with ADRV but not with the group A or group C viruses. Antisera to group A or group C virus reacted only with their respective homologous virus. These results and those of immunofluorescence studies place the human ADRV rotaviruses from China among the group B rotaviruses. We also report the development of an ELISA to detect ADRV; this ELISA should be useful for defining the epidemiology of these recently described rotaviruses.

Adult↗
PubMed1985

Changes in plasma concentrations of thyroxine and triiodothyronine in beef steers fed different levels of propylthiouracil.

Three Latin-square trials were conducted to determine the effects of feeding the thyroid depressant propylthiouracil (PTU) on plasma concentrations of thyroxine (T4) and triiodothyronine (T3) in feedlot steers. In trial 1, four steers were fed 0, 1, 2 or 4 mg PTU/kg body weight daily during five 35-d experimental periods. In trial 2, eight steers were fed 0, .5, 1 or 2 mg PTU/kg body weight daily during five 28-d periods. In trial 3, three steers were fed 0, 1 or 4 mg PTU/kg body weight daily during the first 3 d in each of three 28-d periods. In general, feeding PTU caused increases in plasma T4 concentrations that peaked 5 to 7 d after feeding started. Concurrently, T3 concentrations tended to decrease when PTU was fed. The effects of PTU on hormone concentrations were apparent within approximately 1 to 4 h after PTU feeding started. Furthermore, when PTU was not fed, T4 and T3 concentrations appeared to have rhythmic cycles of 90 and 111 min, respectively, and PTU treatment appeared to interrupt this cyclical pattern. After the initial PTU response, the dose response relationship between PTU level and plasma hormone concentration was not linear. Both 4 and 2 mg PTU appeared to depress both T4 and T3 concentrations, suggesting direct inhibition of the thyroid gland and, for the 1-mg PTU treatment, T4 tended to stabilize at concentrations significantly greater than for 0 mg PTU, while T3 concentrations for 1 mg PTU were slightly lower than for 0 mg PTU.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Intravenous contrast medium and renal cyst.

There are many reasons for what is apparently a benign renal cyst being hyperdense on computed tomography (CT). A previous intravascular contrast material injection (intravenous urogram or arteriogram) within one to three days is cited as one of the possible causes. This prospective study of 13 patients with renal cyst was designed to investigate such a possibility. None of the patients had a hyperdense renal cyst on delayed CT scan following contrast injection. We conclude that intravenous contrast material is not a cause of hyperdensity of a renal cyst on CT.

Contrast Media↗
PubMed1984

Triiodothyronine and thyroxine during gestation in dairy cattle selected for high and low milk production.

Circulating thyroxine, triiodothyronine, and prolactin were analyzed by radioimmunoassay from two groups of pregnant heifers representing genetic populations that differed by 685 kg milk in their first lactation. At 100 days of gestation, blood samples were taken every 15 min for prolactin assay and every 2 h to determine variations of thyroid hormone serum concentration from 0800 to 2000. Basal serum prolactin concentrations in the two genetic groups were not significantly different. A pattern was consistent for both triiodothyronine and thyroxine; concentrations were lower in the morning and higher during the afternoon. Serum triiodothyronine means were not different in the high-producing (1.84 ng/ml) and low-producing heifers (1.86 ng/ml). Serum thyroxine concentrations were significantly higher in the low-producing heifers (67.84 ng/ml) than in high-producing heifers (59.18 ng/ml). The higher thyroxine concentration in pregnant heifers with lower producing ability suggests a negative relationship of thyroxine to milk yield potential.

Animals↗