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Biomedical subjects

M Shao

Publications and source records attributed to M Shao.

44 records · Page 3Linked to original sources
PubMed1991

[Dynamics of endothelial cells of the peripheral area of cornea].

Clinical corneal buttons of 150 cases were stained with try-pan blue and alizalin red S, so as to compare the relative density of endothelial cells and to analyse the forms of the cell nuclei. The result showed that cell densities of fetal corneal endothelium of 25 cases with fetal period from 19 to 34 weeks, had no significant difference (P > 0.05) between the central and peripheral areas of cornea. However, the cell densities of corneal endothelium of 19 cases, aged from newborn to 53 years, showed a significant difference (p < 0.01). The cell nuclei of the fetal corneal endothelium have elliptic forms mainly, which are similar between central and peripheral area of corneal endothelium. However, the forms show an unstable nucleus morphological structure. From newborn to adult cornea, the nucleus forms of corneal endothelial cells tend to be stable and circular, but there are unstable forms of endothelial cell nuclei dispersed in corneal periphery. This emphasize that the endothelial cells in corneal periphery still keep its cell differential function of development in some degree.

Adolescent↗
PubMed1990

[Clinical effects of magnesium sulfate in the treatment of supraventricular tachyarrhythmia].

The obvious effects of magnesium sulfate are noticed not only in ventricular tachyarrhythmia but also in supraventricular tachyarrhythmia (SVTA) which include paroxysmal supraventricular tachycardia (PSVT), chaotic atrial tachycardia (CAT), atrial fibrillation (AF) with rapid heart rate and nonparoxysmal junctional tachycardia (NPJT). This paper reports the effects of magnesium sulfate treatment in 25 cases of SVTA in a self-controlled before and after study. Among 10 cases of PSVT, 6 cases were treated by injection of 25% magnesium sulfate 5-10 ml. Except 2 cases with W-P-W and aberrant ventricular condition, the PS-VT were terminated immediately after half a dose of magnesium sulfate i.v. in 2 cases, other 2 cases were terminated by 5-10 min after a dose of magnesium sulfate i.v.. Some improvements were observed in these 4 cases. The rest 4 cases were prevented by 12 days' intravenous infusion of 1% magnesium sulfate 250 ml per day, 3 cases of them recovered. Three cases of CAT recovered within an hour to two days by infusion of 1% magnesium sulfate 250 ml. Four cases of AF with rapid heart rate were collected, even though it is difficult to determine whether it is due to overdose or inadequacy of digitalis. The heart rates were reduced by magnesium sulfate injection in those 4 cases. Eight cases of NPJT due to heart failure with digitalis intoxication recovered after infusion of 1% magnesium sulfate 250ml within 10 hours to two days. Finally, the mechanism of the effect of magnesium sulfate treatment in SVTA was discussed.

Adult↗
PubMed1985

Effects of occupational lead exposure.

Fifty-three workers in a battery factory, 52 solderers in a television factory, and 50 embroidery workers (a reference group) were studied. The average air lead levels of the three workplaces were 0.578 mg/m3, 0.002 mg/m3, and 0.001 mg/m3, respectively. Adverse effects in terms of clinical manifestations and biochemical criteria were evident among the battery factory workers. A significant dose-response relationship existed between the toxic effects and the air lead levels. The solderers showed no apparent abnormalities in comparison with the embroidery workers. The early clinical manifestations were dysfunction of the central nervous system, indigestion, arthralgia, and myalgia in the extremities. A positive association was observed between the prevalence of fatigue, mild abdominal pain, and arthralgia and the blood lead (PbB), urinary lead (PbU), and zinc protoporphyrin (ZPP) levels. The symptomatic threshold values of PbB, PbU, and ZPP were 30 micrograms/dl (1.5 mumol/l), 0.045 mg/l (0.2 mumol/l), and 40 micrograms/dl (0.7 mumol/l), respectively. The PbB, PbU, free erythrocyte protoporphyrin, and ZPP levels and the blood aminolevulinic dehydratase ratio could be used as indicators of lead exposure, although ZPP is preferred for a preventive monitoring program. The motor and sensory conduction velocities of the median nerve were slower in the exposed groups than in the reference group. No effects on behavioral function were observed among the solderers.

Central Nervous System Diseases↗
PubMed1984

The role of hepatic biotransformation in mediating the acute toxicity of the phosphorothionate insecticide chlorpyrifos.

The apparent (app) Km and app Vmax for mouse hepatic microsomal oxidative detoxification of chlorpyrifos to 3,5,6-tricholoro-2-pyridinol were 16.10 +/- 6.8 microM and 263.2 +/- 22.5 nmol/liver/min, respectively. The app Km and app Vmax for the oxidative activation of chlorpyrifos to chlorpyrifos oxon were 20.0 +/- 6.5 microM and 126.1 +/- 14.6 nmol/liver/min, respectively, whereas the app Km and app Vmax for hepatic microsomal hydrolysis of chlorpyrifos oxon to 3,5,6-trichloro-2-pyridinol were 1.87 +/- 0.36 mM and 89,450.7 +/- 12,087.3 nmol/liver/min, respectively. Under first-order conditions the capacity of mouse hepatic microsomes to detoxify chlorpyrifos oxon exceeded their capacity to generate this potent cholinesterase inhibitor from chlorpyrifos by a factor of 7.6. Pretreatment of mice with phenobarbital (70 mg/kg daily for 4 days) resulted in a 2.5-fold increase in the app Vmax's for oxidative activation and detoxification of chlorpyrifos, and a 1.6-fold increase in the app Vmax for hydrolysis of chlorpyrifos oxon. The app Km's were not altered by phenobarbital pretreatment. Administration of beta-naphthoflavone (80 mg/kg/daily for 2 days) to mice resulted in a slight decrease in the app Vmax's for oxidative activation and detoxification of chlorpyrifos, without altering the app Km's of the same reactions, or the hydrolysis of chlorpyrifos oxon. Phenobarbital and beta-naphthoflavone increased and decreased, respectively, the predicted hepatic clearance of chlorpyrifos. The acute toxicity of chlorpyrifos was slightly antagonized by phenobarbital pretreatment, but was potentiated by beta-naphthoflavone administration. These pretreatments did not affect cholinesterase, nonspecific esterase, or plasma A-esterase activities. Collectively, these results suggest that chlorpyrifos oxon formed within the liver does not escape hydrolysis by the liver, and that extrahepatic sites of activation are important in directly mediating the acute toxicity of chlorpyrifos.

Animals↗
PubMed1984

Chronic administration of an organophosphorus insecticide to rats alters cholinergic muscarinic receptors in the pancreas.

Male rats were treated for 10 days with the organophosphorus insecticide, acetylcholinesterase inhibitor, O,O-diethyl S-[2-(ethylthio)ethyl] phosphorodithioate (disulfoton, 2 mg/kg/day by gavage). At the end of the treatment, binding of [3H]quinuclidinyl benzilate ( [3H]QNB) to cholinergic muscarinic receptors and cholinesterase (ChE) activity were assayed in the pancreas. Functional activity of pancreatic muscarinic receptor was investigated by determining carbachol-stimulated secretion of alpha-amylase in vitro. ChE activity and [3H]QNB binding were significantly decreased in the pancreas from disulfoton-treated rats. The alteration of [3H]QNB binding was due to a decrease in muscarinic receptor density with no change in the affinity. Basal secretion of amylase from pancreas in vitro was not altered, but carbachol-stimulated secretion was decreased. The effect appeared to be specific since pancreozymin was able to induce the same amylase release from pancreases of control and treated rats. The results suggest that repeated exposures to sublethal doses of an organophosphorus insecticide lead to a biochemical and functional alteration of cholinergic muscarinic receptors in the pancreas.

Animals↗
PubMed1984

The interaction of the phosphorothioate insecticides chlorpyrifos and parathion and their oxygen analogues with bovine serum albumin.

The distribution and subsequent toxicity of hazardous chemicals can be influenced by their interactions with plasma proteins. In the present study reversible binding of the phosphorothioate insecticides chlorpyrifos and parathion to fatty acid-free bovine serum albumin (BSA) was examined using the technique of equilibrium dialysis. Computer analyses of the binding data revealed that chlorpyrifos and parathion each bound reversibly to a single class of binding sites on BSA, with apparent KD values of 3.4 +/- 0.1 and 11.1 +/- 0.3 microM, respectively. Additionally, the maximal number of binding sites for each insecticide per molecule of BSA was one. Displacement studies using both chlorpyrifos and parathion indicated that each was a competitive inhibitor of the other's binding, suggesting that they were bound to the same site. Incubation of chlorpyrifos oxon or paraoxon with a 1% solution of BSA resulted in limited, EDTA-insensitive formation of 3,5,6-trichloro-2-pyridinol or p-nitrophenol, respectively. Pretreatment of BSA with 5 mM paraoxon, chlorpyrifos oxon, or 1 mM diisopropylfluorophosphate did not alter this activity, suggesting that these reactions resulted from an esterase-like capacity of BSA, and not from phosphorylation of BSA by these oxons.

Animals↗