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Biomedical subjects

D Xiao

Publications and source records attributed to D Xiao.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effects of quercetin on aggregation and intracellular free calcium of platelets.

AIM: To study the effects of Que on the intraplatelet free calcium concentration and the effects of calcium on the inhibition of platelet aggregation by Que. METHODS: Using Quin-2 fluorescence technique. RESULTS: Que inhibited the platelet aggregation and the rise of [Ca2+]i induced by thrombin in platelets. The values of IC50 and 95% confidence interval were 146.2 (92.4 - 231.3) and 78.5 (49.5 - 124.4) mumol.L-1, respectively. The inhibitory effects of Que on platelet aggregation induced by thrombin were reduced by adding calcium to the medium, and Que had no effect on thrombin-induced internal Ca2+ release from dense tubular system. CONCLUSION: The inhibitory effects of Que on aggregation and the rise of [Ca2+]i in platelets was mainly due to an inhibition of Ca2+ influx.

Adult↗
PubMed1995

Effect of phorbol ester on cAMP-dependent protein kinase activity in cardiomyocytes.

Cardiomyocytes isolated from neonatal rats were treated with phorbol-12-myristate-13-acetate (PMA) ranging from 10(-11) to 10(-7) mol/L for 20 min, causing cytosol protein kinase A (PKA) activity to decrease while particulate PKA activity increase in a concentration-dependent manner. The change of PKA activity induced by PMA was abolished completely by pretreatment of polymyxin B or depletion of protein kinase C (PKC). Type II PKA activity in particulate fraction was enhanced remarkably, while that of type I PKA was not altered when the cells were treated with 100 nmol/L PMA. The results suggested that subcellular distribution and activity of PKA in cardiomyocytes may be regulated by PKC.

Animals↗
PubMed1994

Effects of quercetin on Na(+)-K(+)-exchanging ATPase and Ca(2+) Mg(2+)-ATPase in rats.

Quercetin (Que) ig 200 mg.kg-1, qd x 14 d decreased activities of the Na(+)-K(+)-exchanging ATPase (I) of rat brain plasma membranes and heart sarcolemmal and Ca(2+) Mg(2+)-ATPase (II) of heart sarcolemmal membrane. Que 100 mg.kg-1 reduced the activity of I from rat heart sarcolemmal preparation, but had no effect on that from rat brain plasma membranes. The result shows that I of myocardium is more sensitive than that of brain in rat. Que also showed a remarkable inhibitory effect in the II of heart sarcolemma.

Animals↗
PubMed1993

[The relation between protective effect of moxibustion on gastric mucosa and mucus].

Our previous works have proved that moxibustion at "ShenJue" plays a role in protecting gastric mucosa in the experimental gastric ulcer model rat. The present studies are designed to determine whether the mechanisms of moxibustion protecting gastric mucosa are mediated by mucus. The results are as follows: Either before or after the experimental gastric ulcer model had formed, moxibustion treatment would markedly increase the ratio of PAS positive staining layer to total length of gastric gland (p < 0.05), and the combined gastric mucus of stomach (P < 0.05). These results are negatively correlated to gastric ulcer area and suggest that the mechanisms of moxibustion protection on gastric mucosa are mediated by mucus in the experimental gastric ulcer model rat.

Animals↗
PubMed1993

Effects of quercetin on platelet and reperfusion-induced arrhythmias in rats.

The role of platelets in reperfusion arrhythmias (RA) and the efficacy of quercetin (Que) in preventing the arrhythmias were investigated in anesthetized rats. Platelet count (PC) was performed, the ultrastructure of platelets was scrutinized, and the levels of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (Keto-PGF1 alpha) in plasma were determined by radioimmunoassay (RIA). The pretreatment with Que (5 mg.kg-1) 2 min prior to reperfusion inhibited RA. Que remarkably improved the ultrastructural deviation of platelet, inhibited the platelet aggregation and thromboxane A2 (TXA2) formation, and increased the prostacyclin (PGI2) generation and the ratio of PGI2/TXA2. The decrease in PC and increase in TXB2 level in plasma indicated the participation of platelets in the arrhythmogenic activity of ischemia and reperfusion. The results showed that Que produced a protective effect against RA probably through inhibiting the platelet aggregation, TXA2 formation and increasing the PGI2 generation.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

[Effect of lipopolysaccharide on cytosolic free calcium concentration in myeloma cells].

The concentration of cytosolic free calcium was measured using the fluorescent Ca(2+)-indicator quin 2, and the effect of lipopolysaccharide (LPS) on cytosolic free calcium in myeloma cells was studied. Incubation of myeloma cells with LPS elicited a significant increase in cytosolic free calcium, and inhibited the phytohaemagglutinin (PHA)-induced elevation in cytosolic free calcium. Treatment of the cells with phorbol-12-myristate-13-acetate (PMA) failed to affect the concentration of cytosolic free calcium in resting cells, but inhibited the subsequent PHA-induced elevation in cytosolic free calcium. It is suggested that LPS causes alterations in intracellular calcium homeostasis and perturbations in the calcium-dependent signal transduction pathway.

Animals↗
PubMed1992

First-order analysis of optical flow in monkey brain.

Optical flow is a rich source of information about the three-dimensional motion and structure of the visual environment. Little is known of how the brain derives this information. One possibility is that it analyzes first-order elementary components of optical flow, such as expansion, rotation, and shear. Using a combination of physiological recordings and modeling techniques, we investigated the contribution of the middle superior temporal area (MST), a third-order cortical area in the dorsal visual pathway that receives inputs from the medial temporal area (MT). The results show (i) that MST cells, but not MT cells, are selective for elementary flow components (EFCs) alone or their combination with translation, (ii) that MST cells selective for an EFC do not extract this component from a more complex motion pattern, and (iii) that position invariance as observed in MST is compatible with an input arrangement from MT cells matching the selectivity of MST neurons.

Animals↗
PubMed1992

[Effects of moxibustion on experimental gastric ulcer in rats].

This study was designed to determine whether moxibustion at "Shenjue" plays a role in protecting gastric mucosa in rats. The areas and histological changes of gastric ulcer were examined. The results were as follows: 1. Moxibustion pretreatment within 3 weeks significantly prevented the formation of gastric ulcer. 2. As gastric ulcer had formed, moxibustion couldn't shorten the period of recovery of gastric ulcer. The results suggested that moxibustion pretreatment at "Shenjue" had a protective effect on gastric mucosa. After the experimental ulcer had formed, however, the moxibustion had little protective effect on it.

Acetates↗