Biomedical subjects

Y Luan

Publications and source records attributed to Y Luan.

4 recordsLinked to original sources

PubMed1992

[Study on variation of plasma gamma-aminobutyric acid concentration in rat model of hepatic encephalopathy due to fulminant hepatic failure].

The plasma gamma-aminobutyric acid (GABA) concentration was measured by a radio-receptor assay in rat model of hepatic encephalopathy due to fulminant hepatic failure (FHF) induced by intraperitoneal injection of D-galactosamine (GalN). The results showed that, in FHF group, the plasma GABA increased parallelly with the degree of hepatic encephalopathy after GalN i.p. (r = 0.944, P less than 0.05). In about 48 h, mean plasma GABA concentration was elevated nearly 8-fold. These findings suggest that, in liver failure, elevated plasma GABA concentration may play a role in the pathogenesis of hepatic encephalopathy.

Animals↗

PubMed1990

[Reconstitution of rabbit brain GABA binding protein (receptor) on Xenopus oocytes].

Gurdon's Xenopus laevis oocyte translation system has been extensively employed to investigate the molecular biology of gamma-aminobutyric acid (GABA) receptors in the brains of embryonic chick, rat, etc. As GABA and its receptor may play a role in the pathogenesis of hepatic encephalopathy and a rabbit model of fulminant hepatitis has been established, we reconstituted the rabbit model of fulminant hepatitis has been established, we reconstituted the rabbit brain GABA binding protein (receptor) on Xenopus laevis oocytes to offer a base for further study of the pathological effects of GABA receptor at molecular level. In this report, total RNA was extracted from rabbit brain by guanidine hydrochloride method. The total RNA was then subjected to oligo-(dT)-cellulose affinity chromatography to isolate mRNA. All the RNA samples achieved a high purity with an average OD260/OD280 ratio of about 2.10. The clear bands of 18 S and 28S rRNA in electrophoresis implied that the RNA was not degraded and was therefore available for expression. After two days of incubation of the oocytes injected with mRNA, radioreceptor assay indicated that saturable and specifically displaceable GABA binding sites were implanted onto the oocyte membrane. This result led us to the conclusion that rabbit brain GABA binding protein (receptor) can be reconstituted by injecting exogenous mRNA inclusive of those encoding the receptor into Xenopus oocytes. However, the functional activity of the reconstituted receptor as a GABA gated chloride ion channel needs to be further characterized by patch clamping.

Animals↗

PubMed1990

[QSAR studies on the anticonvulsant activity of 5-substitutedphenyl-1-hydro- and 1-propyl-3-pyrazolidinones].

The chemical structure and anticonvulsant activity relationship of some 5-substituted phenyl-3-pyrazolidinone derivatives were studied. Six pairs (1-hydro and 1-propyl substituted) of compounds were designed and synthesized according to the Topliss improved method, and a compound with the highest anticonvulsant activity was found, i.e. 5-(4-fluorophenyl)-1-propyl-3-pyrazolidinone, ED50 14.7 mg/kg (MES Test). QSAR analysis showed that the hydrophobic constant sigma pi greatly influenced their anticonvulsant activity, and the steric parameter (B4) and electronic parameter (I x 10(2] of the substitutions on the phenyl ring can improve the correlation coefficient (r). Smaller steric volume and more powerful electron withdrawing effect of the substitution on the 5-phenyl ring increased the anticonvulsant activity.

Animals↗

PubMed1987

Yeast calmodulin: structural and functional differences compared with vertebrate calmodulin.

Calmodulin of the baker's yeast (Saccharomyces cerevisiae) showed a similar affinity for Ca2+ to that of vertebrate calmodulin. The maximum binding number of Ca2+ to yeast calmodulin was, however, 3 mol/mol, which is lower than that of vertebrate calmodulin (4 mol/mol). The same maximum activity of porcine brain phosphodiesterase was attained when 100 times higher concentration of yeast calmodulin than that of vertebrate calmodulin was added. On the other hand, the maximum activation of chicken gizzard myosin light chain kinase was attained with 1,000 times higher concentration of yeast calmodulin than that of vertebrate calmodulin, and the maximum activity with yeast calmodulin was less than 1/5 of that with vertebrate calmodulin. Several amino acid substitutions observed in the yeast calmodulin, particularly at the alpha-helical rod connecting the two globular domains, may affect the interaction mode of various target enzymes with this calmodulin.

3',5'-Cyclic-AMP Phosphodiesterases↗