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Biomedical subjects

C G Qian

Publications and source records attributed to C G Qian.

5 recordsLinked to original sources
PubMed1991

Biosynthesis of choline plasmalogens in neonatal rat myocytes.

The alk-1-enyl bond in plasmenylethanolamine is formed from plasmanylethanolamine by the action of a microsomal cytochrome b5-dependent desaturase. However, the origin of the alk-1-enyl linkage in plasmenylcholine, a significant subclass of phospholipids in heart tissues of certain animal species, is not yet known. We have used neonatal rat myocytes as a model to study the biosynthesis of plasmenylcholine in the present studies since they have a phospholipid composition and subclasses of 1,2-diradyl-sn-glycero-3-phosphocholine (-GPC) similar to those of neonatal rat hearts. When equal concentrations of [3H]hexadecyllyso-GPC or [3H]hexadecyllyso-sn-glycero-3-phosphoethanolamine (-GPE) are incubated under identical conditions with myocytes for 4, 12, and 24 h, the rate of plasmenylcholine formation is faster from [3H]hexadecyllyso-GPE than from [3H]hexadecyllyso-GPC. Also, when [3H]alkyllyso-GPC and alkyllyso-[N-methyl-14C]GPC are incubated with rat myocytes for various times up to 24 h, the 3H/14C ratio in the diacyl-GPC plus alkylacyl-GPC fraction and alkyllyso-GPC remains relatively constant (3H/14C = 2.7), whereas the 3H/14C of plasmenylcholine increases from 0.3 at 2 h to 1.7 after 24 h. Finally, when the rat myocytes are prelabeled with [3H]alkyllyso-GPE for 4 h and then reincubated with either [14C]choline or [14C]methionine for 1 or 3 h, both [14C]choline and [14C]methionine are incorporated into plasmenylcholine, except the 14C/3H is much higher (5- to 15-fold) in the [14C]choline-labeled plasmenylcholine than in the [14C]methionine-labeled plasmenylcholine. Collectively, our data show plasmenylcholine is not directly derived from plasmanylcholine or lysoplasmanylcholine, but instead is formed from plasmenylethanolamine via some type of hydrolytic exchange mechanism, and the contribution of plasmenylethanolamine through methylation to the synthesis of plasmenylcholine is of limited capacity.

Animals↗
PubMed1989

The efficacy of triclabendazole (Fasinex) against immature and adult Fasciola hepatica in experimentally infected cattle.

Eighteen Chinese cattle were experimentally infected with metacercariae of Fasciola hepatica and randomly assigned to 6 groups. Five groups of cattle were treated with a single oral dose of triclabendazole at a dose rate of 12 mg kg-1. At necropsy, the reduction in fluke burden compared with the untreated group was 85, 99.6, 99.8, 100 and 100% for cattle treated 2, 6, 8, 12 and 16 weeks after infection, respectively. Data are also presented on body weight changes during the experimental period and on serum gamma-GT activity in cattle from selected groups. Triclabendazole is considered to be safer and more efficacious than currently available fasciolicides in China.

Animals↗
PubMedDate not supplied

Metabolism of platelet activating factor (PAF) and related ether lipids by neonatal rat myocytes.

Suspensions of neonatal rat myocytes were used to investigate the metabolism of [3H]PAF (1-alkyl-2-acetyl-(sn-glycero-3-phosphocholine) (GPC] and [3H]alkyllyso-GPC. [3H]Alkylacyl-GPC consisting of molecular species with four or more double bonds (87%) was the major metabolite formed when either [3H]PAF (4 x 10(-6) - 4 x 10(-9) M) or [3H]alkyllyso-GPC (2 x 10(-7) M) was the precursor. However, substantial amounts of [3H]alkyllyso-GPC (mostly in the media) were also generated from [3H]PAF during the early periods of the incubations. At 2 x 10(-7) M or higher concentrations of either [3H]PAF or [3H]alkyllyso-GPC, [3H]alkylglycerols were also formed (4-12% of the total radioactivity). The [3H]alkylglycerols appear to be produced from [3H]alkyllyso-GPC through the combined actions of lysophospholipase D and a phosphatase. Pretreatment of neonatal rat myocytes with phenylmethylsulfonyl fluoride partially blocked the deacetylation of [3H]PAF and decreased both the formation and subsequent acylation of [3H]alkyllyso-GPC in intact cells. Phenylmethylsulfonyl fluoride also significantly inhibited the activity of cytosolic acetylhydrolase, but it had no direct effect on the microsomal transacylase in vitro. Our data demonstrate that the metabolism of PAF and alkyllyso-GPC by neonatal rat myocytes is qualitatively, but not quantitatively, similar to what occurs in other cell types. In addition, when [3H]alkylacetylglycerol was the precursor, 75% of the label appeared as alkylglycerols in the neonatal rat myocytes, but [3H]PAF was not detected. Therefore, it appears that the de novo pathway via the dithiothreitol-insensitive cholinephosphotransferase step does not contribute to the biosynthesis of PAF in neonatal rat myocytes.

Animals↗