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Biomedical subjects

S Sun

Publications and source records attributed to S Sun.

At least 343 records · Page 19Linked to original sources
PubMed1979

Rapamycin (AY-22,989), a new antifungal antibiotic. IV. Mechanism of action.

Rapamycin, an antifungal antibiotic produced by Streptomyces hygroscopicus showed a strong candicidal activity, which could not be reversed by sterols. It has no effect on efflux of K+, Pi ir U.V. absorbing materials and cell permeability of Candida albicans. Thus, in its action it differs from the polyenes. Mechanism of action of rapamycin appears to be different from many known antifungal agents. In C. albicans, rapamycin at the minimum growth inhibitory concentration inhibited: 1) phosphate incorporation into nucleic acids, 2) acetate incorporation into lipids and 3) substrate respiration of amino acids. The effect on amino acid metabolism was expressed as inhibition of oxidative deamination. At low concentrations rapamycin caused degradation of P32-labeled intracellular macromolecules. Inhibition of threonine incorporation into cell wall and leucine incorporation into cellular protein was observed at relatively higher concentrations of rapamycin. The antibiotic showed no effect on cell-free protein synthesizing systems of Escherichia coli, rat liver and C. albicans and in the mitochondrial enzyme systems. Whether the lethal action of rapamycin on C. albicans is primarily due to one of the above effects or is the result of combined effect on some of these biosynthetic parameters remains to be established.

Amino Acids↗
PubMed1976

Serial liver biopsy observations in hepatitis B antigen carriers by light and electron microscopy.

Liver morphology and function were restudied after an interval of 1 1/2-2 years in 21 Chinese men with hepatitis B antigen (HBsAg). Antigenemia and mild liver histopathology disappeared in one individual who developed antibody to HBsAg(Anti-HBsAg). 20 subjects who were chronic carriers of HBsAg had mild histological abnormalities which were usually persistent and were more commonly lobular than portal. Particularly striking were focal necrosis, eosinophilic bodies, ground-glass cytoplasmic change, and, by electron microscopy, microtubular structures within cytoplasmic membranous cysternae. Interval development of chronic aggressive hepatitis was observed in only one subject. This study suggests that the great majority of HBsAg carriers have a good prognosis at least over a 1 1/2-2-year period, and that liver biopsy is most indicated in those with persistent liver function abnormalities.

Adult↗
PubMedDate not supplied

Chromatography of medicinal plants and Chinese traditional medicines.

Applications of chromatographic techniques to medicinal plants and Chinese traditional medicines are outlined in this review. Areas involved are quantitation of active principles or index or principal components; quality evaluation of crude drugs; identification, characterization and preparative isolation of new compounds for medical use from plants; analysis of pharmaceutical preparations of plant origin and pharmacokinetic and pharmacological studies of herbal drugs and their preparations.

Drugs, Chinese Herbal↗
PubMedDate not supplied

Hypothermic machine perfusion of liver grafts for transplantation: technical development in human discard and miniature swine models.

INTRODUCTION: Cold storage (CS) is the standard preservation technique for liver transplantation (LTx). Hypothermic machine perfusion (HMP) is an alternative preservation technique that provides a continuous supply of substrates and removes waste products. HMP improves early graft function in kidney transplantation, especially for marginal organs: To our knowledge there have been no reports HMP in human LTx. The aim of this study was to develop a reproducible technique for liver HMP prior to initiating a clinical trial. METHODS: For the discard protocol, between May 2001 and March 2002, 10 nontransplantable human livers were obtained. We designed a model of atraumatic, centrifugal HMP of the portal vein (PV) and hepatic artery (HA) via donor vascular conduit. Livers were perfused at 3 degrees C to 5 degrees C with Vasosol solution for 5 to 10 hours using a modified Medtronic Portable Bypass System. Perfusion variables (temp, flow, pressure) where recorded every 30 minutes. During the study, we also validated our techniques in an animal model. For the animal protocol; six swine were used as liver donors and randomized to 12 hours of CS in UW (n = 3) or 12 hours of HMP using Vasosol solution (n = 3). LTx was performed in six swine. Animals survived until postoperative day 5. RESULTS: For the discard protocol, mean HMP time was 6.7 +/- 1.8 hours. Target flow was 0.7 mL/g liver/min. PV and HA pressure ranged from 3 to 5 and 12 to 18 mm Hg, respectively. All grafts were maintained at 3 degrees C to 5 degrees C during HMP. For the animal protocol, all recipients had good liver function and survived to postoperative day 5. AST and TBili were similar between CS and HMP. CONCLUSIONS: Our method of liver HMP appears to be a safe and reliable method to preserve livers. A clinical trial is now underway to evaluate this technique in human LTx.

Adenosine↗