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Biomedical subjects

A Liang

Publications and source records attributed to A Liang.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Reversal effect of Ys-96, a bisbenzylisoquinoline, on adriamycin or vincristine resistance in human cancer cells in vitro].

OBJECTIVE: Reversal effect of Ys-96, a bisbenzylisoquinoline, on the resistance of human cancer cells to adriamycin or vincristine was studied in vitro. METHOD: In an in vitro culture system of human cancer cells MCF-7 and its adriamycin-resistant line MCF-7/Ad or KB and its vincristine-resistant line KBv200, the sensitivity(IC50) of the resistant cell lines to adriamycin or vincristine was evaluated with a MTT assay. RESULT: IC50 value of adriamycin or vincristine in combination with Ys-96 at a concentration of 1.00 mumol/L against MCF-7/Ad or KBv200 was found to be close to that of adriamycin alone or vincristine alone against the sensitive cell line MCF-7 or KB. CONCLUSION: The drug resistance of MCF-7/Ad or KBv200 could be essentially reversed by Ys-96 at a concentration of 1.00 mumol/L.

Benzylisoquinolines↗
PubMed1996

[The status quo and prospect of experimental study on channel tropism of Chinese herbal drugs].

The assay of metabolism and distribution of effective components of Chinese herbal drugs, microelement assay, pharmacodynamic assay and cAMP, cGMP assay are the essential methods usually used in the experimental study of channel tropism of Chinese herbal drugs. The problems of each method as well as the points for attention in the experimental study of channel tropism are discussed.

Animals↗
PubMed1996

Gamma-tubulin is permanently associated with basal bodies in ciliates.

Ciliates are of special interest owing to the multiplicity and diversity of their microtubule organizing centers (MTOCs). The subcellular localization of gamma-tubulin in these protozoa has not been extensively studied. The cloning of a gamma-tubulin gene in Euplotes (Liang, A., K. Heckmann, Gene 136, 319-322 (1993) led us to examine the localization of this protein. We used three polyclonal antibodies, JH46, R58 and R70. They had been raised against peptides common to mammalian and Aspergillus gamma-tubulins. These regions had 69%, 95%, and 75% identity with the corresponding regions of Euplotes gamma-tubulin. Immunoblotting (R70) revealed a polypeptide corresponding to the molecular mass of Euplotes gamma-tubulin. In Euplotes octocarinatus, gamma-tubulin was detected by immunofluorescence (R70) in the basal bodies, the micronucleus and the macronucleus throughout the cell cycle. The presence of gamma-tubulin in basal bodies and micronuclei was confirmed with the other two antibodies JH46 and R58. The permanent association of gamma-tubulin with basal bodies was also observed in Tetrahymena thermophila and Paramecium tetraurelia, two ciliates distantly related to Euplotes. These results not only extend to ciliates the finding that gamma-tubulin is permanently associated with ciliary basal bodies, but also demonstrate that gamma-tubulin is present in unconventional MTOCs.

Amino Acid Sequence↗
PubMed1996

[Effects of processing on specific toxicity and pharmacodynamics of radix Kansui, radix Achyranthis bidentatae and semen Armeniacae amarum].

The comparative toxicological researches on crude and processed drugs show that the activating action of Radix Kansui, Radix Achyranthis Bidentatae and Semen Armeniacae Amarum on EBV-EA can be decreased by processing. Processing can also decrease stimulating activity on mouse skin, inhibit tumor-promoting activity in two stage skin tumor promoting test and lapactic effect by Radix Kansui. Meanwhile the pharmacological effects of these drugs can be retained or increased by processing.

Animals↗
PubMed1996

[Antitussive, expectorant and anti-inflammatory effects of rhizoma Cynanchi stauntonii].

Experiments indicated that the ethanol extract and ether extract from Rhizoma Cynanchi Stauntonii showed obvious antitussive and expectorant effects in mice with stomach administration. The antitussive effect of ethanol extract was stronger than the expectorant effect. The water extract showed a certain expectorant effect but no marked antitussive effect with oral administration. Obvious anti-inflammatory effect was observed on croton oil-caused mouse ear swell with intraperitoneal injection.

Animals↗
PubMed1996

[Pharmacological comparative study on baiqian and baiwei].

The decoction of Cynanchum glaucescens and the ethanol extract of C. stauntonii show significant antitussive and expectorant actions. The decoctions of C. stauntonii or C. glaucescens have antiasthmatic and anti-inflammatory effects. The decoction of C. atratum has some expectorant effect but no antitussive or antiasthmatic actions. On the other hand, the decoction of C. versicolor cannot relieve cough nor sputum. The results indicate that both C. atratum and C. versicolor cannot be used as C. glaucescens or C. stauntonii.

Adolescent↗
PubMed1995

[New theoretical study on the biological origins of Chinese medicinal herbs].

Following the theses on "A theoretical study of the biological origins of Chinese medicinal herbs" in 1991, the authors continued the study and established eleven new views, namely; "The theory of differentiation tendency of Chinese medicinal herbs for regional habitually used drugs"; "The theory of regularity of occurrence of confusing species and pseudo materia"; "Discussion on rich resources of new drugs from old sorts of traditional Chinese medicine"; "The theory of knowledge of substitutes for Chinese medicinal herbs", etc.

Drugs, Chinese Herbal↗
PubMed1995

[Effect of processing on specific toxicity of radix Achyranthis bidentatae].

To activate Epstein-barr virus in Raji cells in vitro the lowest activation concentrations of ether extracts from Radix Achyranthis Bidentatae unprepared (I), stir-baked with wine (II) and stir-baked with salt (III) required were 0.8.20 and 0.16 micrograms/ml respectively. 5 microliters (equal to 250 mg herb weight)/ear of these extracts had inflammatory effect on mouse ear skin in 4 hours. Ethanol extract of I at concentration 0.04-125 mg/ml did not increase the chromosomal aberration rates in CHL cells. The decoctions of I, II, and III given orally at 15 g/kg x 3d showed no effect on micronucleus rates in mouse bone marrow. Ethanol extracts of I, II, and III at 10 g/kg x 10d did not show any evident antifertility action.

Animals↗
PubMed1995

[Theory of similarity between close relative species of toxic medicinal herbs in toxicity and poisoning action].

The article puts forward an opinion that there are identical or similar toxic components and poisoning action among close relative species of toxic medicinal herbs. These components, however, may vary in contents with different species. Many scientific examples are enough to prove that we can take treating, curing and preventative measures effectively only if we hold the conception that "Toxicity and poisoning action to each other may exist in close relative species of toxic medicinal herbs".

Drugs, Chinese Herbal↗
PubMed1995

[Antitussive, expectorant and anti-asthmatic effects of Cynanchum glaucescens (Decne.) Hand. -Mazz].

The water, ethanol and ether extracts from Cynanchum glaucescems administrated orally showed significant antitussive effect in ammonia-induced cough model in mice. The water and ethanol extracts had obvious expectorant effect. The filtered solution of water decoction injected intraperitoneally could effectively prevent guinea pigs from asthma induced by acetulcholine and histamine mixture, and also inhibit the ear inflammation in mice caused by croton oil. All these effects showed close dose-effect relationship.

Animals↗
PubMed1995

[Antifebrile and anti-inflammatory effects of radix Cynanchi atrati].

The water extract of Radix Cynanchi Atrati used as intraperitoneal injection has been proved to have an obvious antifebrile++ effect on rat fever caused by 15% yeast suspension hypodermic injection as well as a significant anti-inflammatory effect. But the antiferbrile effect of its ethanol extract is not clear.

Animals↗
PubMed1993

The macronuclear gamma-tubulin-encoding gene of Euplotes octocarinatus contains two introns and an in-frame TGA.

The gamma-tubulin (gamma-Tub)-encoding gene (gamma-tub) of Euplotes octocarinatus was amplified from macronuclear DNA with the help of the polymerase chain reaction (PCR) and sequenced. The polypeptide deduced from the gene consists of 462 amino acids (aa). It shares 61% aa identity with the Aspergillus nidulans gamma-Tub. The gene contains an in-frame TGA codon and two small pre-mRNA introns (36 and 26 bp). We suggest that the TGA, like TGA codons in the pheromone-encoding genes of E. octocarinatus, codes for a cysteine. This suggestion is supported by the finding that in the gamma-Tub of other organisms, a cysteine is located at this position. Sequencing the mRNA revealed that the introns are absent from the gamma-tub transcripts. The second intron constitutes the shortest one reported so far. We have also sequenced the 5'- and 3'-flanking regions of the gene up to the telomeres and report here the entire sequence of the macronuclear DNA molecule carrying gamma-tub.

Amino Acid Sequence↗
PubMed1981

Coregulation of oxidized nicotinamide adenine dinucleotide (phosphate) transhydrogenase and glutamate dehydrogenase activities in enteric bacteria during nitrogen limitation.

The relationship between oxidized nicotinamide adenine dinucleotide (phosphate) [NAD(P)+] transhydrogenase (EC 1.6.1.1) and NAD(P)+ glutamate dehydrogenase in several enteric bacteria which differ slightly in their regulation of nitrogen metabolism was studied. Escherichia coli strain K-12 was grown on glucose and various concentrations of NH4Cl as the sole nitrogen source. In the range of 0.5 to 20 mM NH4Cl, the energy-independent transhydrogenase increased two to threefold. Comparable changes occurred in NAD(P)+-linked glutamate dehydrogenase. NH4Cl concentrations of 20 to 60 mM resulted in relatively constant specific activities for both enzymes. Higher exogenous NH4Cl, however, led to a decline in both activities. Isocitrate dehydrogenase, another potential source of cellular NADPH, was insensitive to NH4Cl limitation. Similar studies in the presence of glutamate and different exogenous NH4Cl concentrations again showed concerted effects on both enzymes. Growth on glutamate as the sole nitrogen source led to severe repression of both transhydrogenase and glutamate dehydrogenase. In Salmonella typhimurium, both enzymes were unaffected by limiting NH4Cl or growth on glutamate as the sole nitrogen source. Both were, however, repressed by growth on aspartate, a potential source of cellular glutamate. Coordinate changes in glutamate dehydrogenase and transhydrogenase were also evident in Klebsiella aerogenes, particularly under conditions in which glutamate dehydrogenase was regulated inversely to glutamate synthetase. Coordinate changes in glutamate dehydrogenase and transhydrogenase in enteric bacteria are discussed in terms of the possible involvement of the latter enzyme as a direct source of NADPH in the ammonia assimilation system.

Ammonium Chloride↗