Search PubMed⌕ Search

Biomedical subjects

H Luo

Publications and source records attributed to H Luo.

At least 253 records · Page 14Linked to original sources
PubMed1993

Expression of 5-HT1C receptors in transfected MDCK cells is functionally and anatomically asymmetric.

Madin-Darby canine kidney (MDCK) cells were transfected with the cDNA for the rat 5-HT1C receptor (pMV7-SR1c) using electroporation. Cells that survived G418 selection medium were loaded with indo-1 and run through a fluorescence-activated cell sorter (FACS); 10% responded to serotonin (5-HT) with an increase in intracellular Ca2+ concentration ([Ca2+]i). Responding cells were separated with the FACS, grown to confluence, and resorted two more times until a clone of 100% respondents was obtained (SR-MDCK). In SR-MDCK cells grown on porous filters, [Ca2+]i increased only when 5-HT was applied to the basolateral membrane (change in [Ca2+]i = 190 +/- 43 nM); there was no response of [Ca2+]i to apical application of 5-HT. The asymmetric response to 5-HT was likely due to targeting of 5-HT1C receptors exclusively to the basolateral membrane of SR-MDCK cells; 125I-labeled lysergic acid diethylamide binding sites, a marker of high-affinity 5-HT receptors, were located only in the basolateral membrane. These experiments demonstrate that epithelial cells can be stably transfected to express G protein-linked, calcium-mobilizing receptors and that the receptors may be targeted asymmetrically to specific domains of the plasma membrane.

Animals↗
PubMed1993

[Treatment of upper respiratory infection with mixt. 716 compound].

Mixt. 716 is composed of traditional Chinese medicinal herbs, including Oldenlandia diffusa, Euphorbia humifusa, Onychium japonicum, Acalypha australis. 150 cases of upper respiratory infection were divided into 716 treatment group (89 cases) and control group (61 cases) randomly. The effective rate was 92% in treatment group compared with 67% in control group. Experimental studies also showed that Mixt. 716 was slightly cytotoxic, it could obviously inhibit influenza virus A.

Child, Preschool↗
PubMed1993

[Effect of propranolol on circadian rhythm of Goldblatt hypertension in goat].

With the Goldblatt two-kidney two-clip method, persistent hypertension was reproduced in 7 goats. After hypertension was established and stabilized, a beta-receptor inhibitor Propranolol was given to the goats in the usual form of drug administration (20 mg, q 8 h) or in the form of chronotherapy (30 mg, QN). The mean value of BP was computed. The result suggested that, compared with the usual form of therapy, chronotherapy could reduce the hypertension to the same degree, but with less time and less amount of drug.

Animals↗
PubMed1992

Role of cholecystokinin in mediating GRP-stimulated gastric, biliary and pancreatic functions in man.

To explore the mechanisms of gastrin-releasing peptide (GRP)-induced gut functions in man, we investigated the effect on gallbladder contraction, exocrine pancreatic secretion and gastric acid secretion of a recently developed CCK receptor antagonist, loxiglumide, on GRP-stimulated effects in six healthy human subjects. Intravenous infusion of graded doses of synthetic human GRP (1-27 pmol/kg per h) caused significant and dose-dependent increases in pancreatic enzyme and gastric acid secretions and in gallbladder contraction. Intravenous administration of loxiglumide (10 mg/kg per h) abolished GRP-stimulated gallbladder contraction, augmented gastric acid secretion, but did not affect exocrine pancreatic secretion. The results suggest that endogenously released CCK is (1) responsible for GRP-stimulated gallbladder contraction, and (2) involved in regulating gastric acid secretion. The results further suggest that GRP-stimulated pancreatic secretion is not mediated by CCK, but has a direct response of GRP on the exocrine pancreas.

Adult↗
PubMed1992

Protective effect of anisodamine on cultured bovine pulmonary endothelial cell injury induced by oxygen-free radicals.

Anisodamine, a Chinese traditional medicine herb, has been used for treatment of adult respiratory distress syndrome effectively, but little is known about its mechanism. We attempted to investigate if anisodamine could protect bovine pulmonary endothelial cell injury induced by exogenous oxygen-free radicals that were generated by xanthine/xanthine oxidase or opsonized zymosan-stimulated polymorphonuclear leukocytes. Results showed that with the addition of xanthine/xanthine oxidase into cultured bovine pulmonary endothelial cells, production of malondialdehyde and release of lactate dehydrogenase in supernatant increased, and synthesis of prostacyclin decreased. Damaged cellular membranes were revealed by scanning electron microscopy. The same was true for the addition of opsonized zymosan-stimulated polymorphonuclear leukocytes. While treatment with anisodamine greatly attenuated all of the above-mentioned parameters, results showed that (1) cultured bovine pulmonary endothelial cells could be damaged by oxygen-free radicals, (2) anisodamine had a protective effect on this injury as effective as that of superoxide dismutase and catalase, and (3) the membrane-stable action might contribute to the mechanism of protective effect against this injury.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Synthesis and characterization of quaternary ammonium-linked glucuronide metabolites of drugs with an aliphatic tertiary amine group.

A synthetic approach was developed to make the quaternary ammonium-linked glucuronide metabolites of compounds with an aliphatic tertiary amine group. The key step involved quaternization of the compound with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide)uronate and sodium bicarbonate in a two-phase system of water and an organic solvent. The synthetic approach successfully yielded quaternary ammonium-linked glucuronides of 20 drugs and two of their phase I metabolites. The drugs were from various pharmacological classes: H1 antihistamines, antipsychotic agents, and tricyclic antidepressants. Physical data such as HPLC retention times, and diagnostic fast-atom bombardment mass spectra and 1H NMR spectra were obtained. These should aid in the characterization of compounds in samples isolated from biological media.

Amines↗
PubMed1992

Effects of rapamycin on human HLA-unrestricted cell killing.

Rapamycin (RAPA) is a potent immunosuppressant and can effectively prevent allograft rejection at a dosage 10- to 100-fold lower than that of cyclosporin A. RAPA strongly inhibits proliferation and function of T and B cells. In this study, we investigated the effect of RAPA on human HLA-unrestricted cell killing. It was shown that in vitro RAPA inhibited the cytolytic effect of natural killer cells and lymphokine-activated killer cells (LAK) and inhibited antibody-dependent cell-mediated cytotoxicity. The effective concentration of RAPA was 10- to 100-fold higher than that required for inhibiting T cell proliferation. These results suggest that there could be a therapeutic dose window at which RAPA inhibits T cell activity while it leaves HLA-unrestricted cell killing unaffected. We also demonstrated that while IL4 inhibited LAK activity, and RAPA inhibited IL4-promoted T cell proliferation, RAPA was not able to antagonize IL4's inhibitory effect on LAK. This indicates that the mechanism of interaction between RAPA and IL4 on LAK is different from that on T cells.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1992

Inhibition of in vitro immunoglobulin production by rapamycin.

Like FK506, rapamycin, a structural analog of FK506, is a strong immunosuppressant. The immunosuppressive effect of Rapa in in vitro IgG, IgM, and IgA production by human lymphocytes was examined in this study. To inhibit spontaneous or pokeweed mitogen-stimulated production of Ig by human peripheral blood lymphocytes, about one thousandfold lower concentrations of Rapa (IC50 = 0.3 nM-2 nM) were required than of cyclosporine (IC50 = 0.3 microM-2 microM). T cells were the direct targets of Rapa, because preincubation of T cells with Rapa abolished the T cells helper effect to T-dependent Ig production. Rapa also had direct suppressive effect on B cells, since Rapa suppressed IgG production by pure B cells stimulated with IL2 and Staphylococcus aureus Cowan I. Kinetic studies measuring IgG production and cell proliferation revealed that Rapa acted at the activation stage of T and B cells. Exogenous IL2 substantially reversed the inhibitory effect of CsA but not that of Rapa in Ig production. This study is the first report on the strong suppressive effect of Rapa on human humoral immune response with a quantitative comparison with that of CsA. The underlying mechanisms are also explored. The results indicate the potential usefulness of this drug in treatment of presensitized transplantation patients, with whom cytotoxic Ab is a major obstacle to a successful transplantation.

Antibody Formation↗