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Biomedical subjects

C M Liu

Publications and source records attributed to C M Liu.

At least 127 records · Page 7Linked to original sources
PubMed1981

Dynamics and regulation of TSH secretion by superfused anterior pituitary cells.

Superfused dispersed cells respond rapidly to 2- to 10-min pulses of TRH (10(-10) to 10(-7) M) in a dose-dependent manner. The effects of decreasing the stimulus duration can be overcome by a proportional increase in concentration of TRH. A TRH stimulus of 10 min or greater duration results in a sharp peak in TSH secretion followed by a lower plateau. Somatostatin (10(-8) M inhibits the response to TRH (t X 10(-9) M). T3 (2.0 microgram/dl) inhibits TRH-induced TSH secretion by superfused pituitary fragments, but not by dispersed cells. Corticosterone (50 microgram/dl), however, inhibits crude CRF-induced ACTH secretion by such cells.

Adrenal Glands↗
PubMed1980

Microbial products. IV. X-14847, a new aminoglycoside from Micromonospora echinospora.

Micromonospora echinospora strain X-14847 produces gentamicin A as the major antibiotic together with a new aminoglycoside, termed X-14847, and identified as a 2-amino-2-deoxy-alpha-D-glucopyranosyl myo-inositol. This report describes the taxonomy of the culture, fermentation conditions, the isolation and the identification of X-14847.

Aminoglycosides↗
PubMed1979

Isolation and characterization of antibiotic X-14547A, a novel monocarboxylic acid ionophore produced by Streptomyces antibioticus NRRL 8167.

A novel carboxylic acid ionophore, antibiotic X-14547A, closely related to the polyether antibiotics has been isolated along with four other metabolites from fermented cultures of a new strain of Streptomyces antibioticus. The structure, determined by X-ray analysis of the R(+)-1-amino-1-(4-bromophenyl)-ethane salt contained pyrrole carbonyl and trans-butadienyl chromophores in addition to the unusual tetrahydroindane bicyclic ring system. A second novel metabolite was identified as 3-ethyl-1,3-dihydro-3-methoxy-2H-indol-2-one.

Anti-Bacterial Agents↗
PubMed1979

Induction of resistance to aurodox by aurodox in the antibiotic-producing culture, Streptomyces goldiniensis.

The sensitivity of protein and aurodox synthesis to aurodox was examined in relationship to the development of resistance to aurodix on Streptomyces goldiniensis during fermentation. It was found that the culture remains sensitive to the antibiotic as long as no aurodox is present in the medium. Resistance only develops when aurodox is present, either exogenously added or endogenously synthesized by the culture. These observations suggest that the development of resistance is an inducible process, and evidence is presented indicating that aurodox induces a specific resistance system in S. goldiniensis.

Anti-Bacterial Agents↗
PubMed1979

Conglobatin, a novel macrolide dilactone from Streptomyces conglobatus ATCC 31005.

Fermentation of deposited cultures of Streptomyces conglobatus, known to produce the polyether antibiotic, ionomycin has resulted in the isolation and characterization of a second metabolite, conglobatin (C28H38N2O6). X-Ray analysis revealed a dimeric macrolide dilactone structure for conglobatin, similar to the structures of the mold metabolites vermiculin and pyrenophorin, from which the absolute configuration of conglobatin has been inferred. The dimer consists of two molecules of 7-hydroxy-8-oxazoyl-2,4,6-trimethyl-2-octenoic acid joined by two ester linkages.

Animals↗
PubMed1976

Studies on a new polyether antibiotic, Ro 21-6150.

A new polyether antibiotic, Ro 21-6150, has been isolated from culture broths of Streptomyces hygroscopicus, strain X-14563. Ro 21-6150 has ionophore properties and is active in vitro against gram-positive bacteria.

Animals↗