Search PubMed⌕ Search

Biomedical subjects

Y T Liu

Publications and source records attributed to Y T Liu.

At least 91 records · Page 5Linked to original sources
PubMed1987

Factors affecting the production of amphotericin A.

Factors affecting amphotericin A synthesis of Streptomyces nodosus, NDMC-034 were studied. Iron, magnesium and manganese were found to stimulate amphotericin A synthesis at concentrations ranging from 10-100 microM. The optimum inoculum size, and the pH of production medium before sterilization for producing amphotericin A, were found to be near 10% (v/v) and pH 7.8, respectively. Carrying out fermentation in a complex medium using pharmamedia as nitrogen source resulted in an amphotericin A yield of up to 3.4 g/liter. A novel isolation and purification process for amphotericin A from the fermentation broth was developed, using an extracting isopropyl alcohol and methanolic solution containing 2% CaCl2. Amphotericin A exhibits a much lower acute toxicity in mice than amphotericin B.

Amphotericin B↗
PubMed1986

A new antitumor antibiotic, chounghwamycin A. I. Taxonomy, isolation and characterization.

Chounghwamycin A, a new antitumor antibiotic produced by a strain of Streptomyces sp. No. PL-D-5, was isolated and characterized. It appeared to belong to the actinomycin group of antibiotics from physico-chemical studies and has an empirical formula of C63H88N11O21. The antibiotic is extractable into an organic solvent from the fermentation broth, possessing potent antileukemic activity against P388 mouse leukemia in mice and antimicrobial activity against Gram-positive bacteria with MIC values about 0.1-0.4 microgram/ml, but showed no activity on Gram-negative bacteria, yeast and fungi tested.

Animals↗
PubMed1984

Biosynthetic studies of amphotericins, candicidin and nystatin by means of mutation.

A novel mutant strain designated as Streptomyces nodosus, NDMC-034 was selected from the mutation of Streptomyces nodosus, IMRU 3694. This mutant was characterized by delayed sporulation, the incapability of producing the melanoid pigment either in the production medium or on YD agar containing 1% yeast extract and 1% dextrose, and the increased yield of amphotericin A as compared to its parent strain. In addition, the biosynthesis of amphotericin A by this mutant seems to be sensitive to temperature. When the incubation temperature was raised to 32 degrees C, the yield of amphotericin A was dramatically decreased; in contrast, the yield of amphotericin B was greatly increased as compared to that at 28 degrees C. Another unique mutant strain designated as Streptomyces griseus, YT-1 was selected from the mutation of Streptomyces griseus, IMRU 3570. It was characterized by the incapability of synthesizing candicidin and the delayed sporulation. All the mutants were auxanographed and characterized by the requirement for growth factor.

Amphotericin B↗
PubMed1982

Effects of type A botulinus toxin on primary chick embryo cell culture.

Type A botulinus toxin was studied for its ability to inhibit the DNA, RNA, and protein synthesis of a chick embryo primary cell culture. 3H-thymidine, 3H-uridine, and 14C-leucine were employed as tracers for measuring the synthesis of DNA, RNA, and protein, respectively. In the presence of large doses (2 x 10(6) MLD/ml) of type A botulinus toxin, RNA synthesis was inhibited to a lesser extent than DNA synthesis, and a very weak inhibition of protein synthesis was observed. The effect of type A botulinus toxin on DNA synthesis of a chick embryo brain cell suspension culture was also tested. The DNA synthesis of the brain cells was strongly inhibited by this toxin.

Animals↗