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Biomedical subjects

G T Liu

Publications and source records attributed to G T Liu.

At least 127 records · Page 7Linked to original sources
PubMed1991

Delayed oculogyric crises associated with striatocapsular infarction.

Oculogyric crises are dystonic, usually upward, conjugate eye deviations. We describe an 11-year-old girl who developed oculogyric crises 3 1/2 years after infarction of the right caudate, putamen, and internal capsule. Her abnormal eye movements responded to anticholinergic agents. This is the first reported association between oculogyric crises and striatocapsular infarction.

Benztropine↗
PubMed1991

Mutagenicity of Alternaria alternata and Penicillium cyclopium isolated from grains in an area of high incidence of oesophageal cancer--Linxian, China.

In order to study the relationship between daily consumption of mouldy food and the incidence of oesophageal cancer, we examined the mutagenicity of Alternaria alternata and Penicillium cyclopium, which seriously contaminate grain in Linxian county, China. We first examined extracts of cultured strains of A. alternata. In the reverse mutation test, positive results were obtained in 85% of strains; positive results were seen in 84% of 19/20 strains in the rec assay. Eight of ten strains induced sister chromatid exchange, and two of eight strains induced chromatid breaks. Six of seven strains induced unscheduled DNA synthesis and DNA synthesis inhibition. One extract induced a higher frequency of sister chromatid exchange in lymphocytes from normal persons than in those from patients with oesophageal cancer, and the spontaneous break-points in patients were related to fragile sites and neoplasia-associated break-points. The toxins alternariol and its monomethyl ether, produced by A. alternata, were examined in the reverse mutation assay and for unscheduled DNA synthesis. The results were similar to those obtained with extracts of the different strains. Alternariol had a four to eight times greater effect than its monomethyl ether. Of 24 strains of P. cyclopium isolated from cereals in Linxian, four were cultured with rice and 19 in Raulin-Thom medium. Cultures in Raulin-Thorn medium, solution and hyphae were then extracted. The strains cultured with rice induced sister chromatid exchange, unscheduled DNA synthesis and DNA synthesis inhibition. The solution extracts of 14 strains were positive in the rec assay, and five strains were positive in the reverse mutation test.(ABSTRACT TRUNCATED AT 250 WORDS)

Alternaria↗
PubMed1991

Relationships between Alternaria alternata and oesophageal cancer.

Although it is uncertain whether fungi can produce the mycotoxins that induce oesophageal cancer, the tumorigenicity of fungi isolated from grain in an area of high incidence of oesophageal cancer has been confirmed. Alternaria alternata is a fungus of importance in this respect. The contamination rate with A. alternata in corn from areas of high morbidity from oesophageal cancer is higher than that in low-morbidity areas. Extracts of A. alternata induced reverse mutation in Escherichia coli, unscheduled DNA synthesis in cultured human amnion FL cells, chromosomal aberrations and sister chromatid exchange in human peripheral blood lymphocytes, mutation in V79 cells and transformation of NIH3T3 cells. Alternariol methyl ether, which is an active compound produced by this fungus, also induced transformation of NIH3T3 cells, and the transformed cells grew in soft agar and were tumorigenic in nude mice. Food mildewed by this fungus induced forestomach tumours in rats. Thus, (i) A. alternata is tumorigenic, (ii) it has been isolated from corn in an area of high incidence of oesophageal cancer, and (iii) contamination with A. alternata in the area of high incidence is higher than that in the area of low incidence. We therefore believe that A. alternata is one of the causes of human oesophageal cancer.

Alternaria↗
PubMed1990

Scavenging effect of schizandrins on active oxygen radicals.

The reactive oxygen radicals produced from human polymorphonuclear leukocytes (PMN) stimulated with PMA (phorbol myristate acetate), hydroxyl radicals generated by a Fenton reaction, and superoxide anion radicals produced by irradiating solutions of riboflavin in the presence of EDTA have been taken as the models for production of oxygen radicals. With the use of the electron spin resonance spin trapping method, the scavenging effects of schizandrol A (solA) (5 x 10(-4) M) and schizandrin B (sinB) (5 x 10(-4) M) have been studied and compared with the effects of vitamin E (5 x 10(-4) M) and vitamin C (5 x 10(-4) M). It has been found that in cell system the scavenging effects of sinB and solA, as judged by ESR spin trappings, on hydrpxyl radicals (.OH) are greater than vitamin E and vitamin C and the scavenging effects on superoxide anion (O2) are greater than vitamin E but lower than vitamin C. With respect to the Fenton reaction, sinB has the strogest scavenging effect on .OH (77%) and solA has strong scavenging effect on .OH (63%), both of them larger than that of vitamin E (35%) and vitamin C (56%). In the riboflavin/EDTA system, the scavenging effect of sinB (46%) is smaller than that of vitamin C (96%) but larger than that of vitamin E (23%); the scavenging effect of solA is not obvious (14%). With the use of spin probe oximetry, the oxygen consumption during the respiratory burst of stimulated PMN has been measured when exposed to schizandrins. The experiment results demonstrated that they do not affect the activity of production of active oxygen radicals in the respiratory burst of PMN stimulated with PMA.

Cyclooctanes↗
PubMed1990

Scavenging effects on active oxygen radicals by schizandrins with different structures and configurations.

We have studied the scavenging effects of different structures and configurations of schizandrins isolated from Fructus Schizandrae, a traditional Chinese herb, on active oxygen radicals with the method of spin-trapping technique. The active oxygen radicals were produced from human polymorphonuclear leukocytes (PMN) stimulated with phorbol myristate acetate (PMA). In addition, the scavenging effects of schizandrins on hydroxyl radicals (.OH) in Fenton's reaction and the scavenging effects on superoxide anions (O2-.) in both riboflavin/EDTA and xanthine/xanthine oxidase systems have also been studied. They are compared with the scavenging effects of both Vitamin C (Vc) and Vitamin E (VE). The experimental results have shown that the scavenging effect of schizandrin B (Sin B) on the active oxygen radicals is stronger than that of S(-) Sin B and R(+) Sin B. For schizandrins of the same molecular structures with different stereoconfigurations the scavenging effects of S type of the benzene ring on active oxygen radicals are stronger than those of R type and for schizandrins of the same stereoconfigurations with different structures the scavenging effects of schizandrin C (Sin C) on the active oxygen radicals are stronger than those of Sin B.

Cyclooctanes↗
PubMed1990

Detection of free radical scavenging activity of schisanhenol by electron spin resonance.

It was reported that Schisanhenol (Sal) isolated from Schisandrae Rubriflora inhibited lipid peroxidation induced by ferrous-cysteine and NADPH-ascorbic acid. In this studies the oxygen radical scavenging activity of Sal was detected by electron spin resonance (ESR) and spin trapping. Sal was shown to scavenge oxygen radicals produced by human neutrophils (Neu) stimulated by tetradecanoylphorbol acetate (TDPA). But no effect of Sal was seen on oxygen consumption measured by spin label oximetry in Neu during respiratory burst. In Fenton reaction system, the inhibitory rate of hydroxyl radical by Sal was 34.4%. In xanthine-xanthine oxidase and uv-irradiation of riboflavin systems, Sal scavenged superoxide anion radical by 26.1% and 21.9%, respectively. In all these systems the action of Sal was more potent than that of vitamin E. It may be concluded that Sal possesses a free radical-scavenging activity.

Cyclooctanes↗
PubMed1990

[Induction by kopsinine of hepatic mixed-function oxidase in mice].

Kopsinine is an indole alkaloid. Oral administration of kopsinine 200 mg/kg once daily for 3 d significantly increased liver microsomal protein, cytochrome P-450, cytochrome b5, NADPH-cytochrome C reductase, aminopyrine demethylase and benzo(a)pyrine hydroxylase activities in mice. kopsinine only induced cytochrome P-450 in rough endoplasmic reticulum of liver. SDS-polyamine gel electrophoresis analysis showed that the protein bands of microsomes from kopsinine treated mice were similar to that induced by phenobarbital in mice. Metyrapon, a specific inhibitor of cytochrome P-450, partially antagonized aminopyrine demethylase activity of microsomes from mice treated with kopsinine. The results suggest that kopsinine yields a pentobarbital-like induction on liver mixed function oxidase in mice. In addition, kopsinine was found to shorten the barbital-induced sleeping time in mice.

Administration, Oral↗
PubMed1990

[Effects of schizandrin B and schisanhenol on drug metabolizing-phase II enzymes and estradiol metabolism].

Intragastric gavage of schizandrin B (Sin B) and schisanhenol (Sal) 200 mg/kg once daily for 3 d significantly increased liver glutathione-S-transferase (GSH-S-T) and microsomal cytochrome P-450 in mice and rats. Sin B and Sal antagonized the increase of uterus weight induced by sc estradiol in ovariectomized, and decreased serum estradiol level in mice. RIA and HPLC showed an enhancement in [3H] estradiol metabolism by liver microsomes from Sin B- and Sal-treated mice. The results indicated that both Sin B and Sal have inductive actions on drug metabolizing-phase I and phase II enzymes in mice and rats.

Animals↗
PubMed1990

Penicillamine-induced ocular myasthenia gravis in rheumatoid arthritis.

We report a case of a 47-year-old woman with rheumatoid arthritis who developed ocular myasthenia gravis during penicillamine treatment. Her serum contained elevated titers of acetylcholine receptor antibodies, and her symptoms resolved 8 weeks after discontinuation of penicillamine. We review the clinical and laboratory features of this syndrome of penicillamine-induced myasthenia gravis and discuss its pathophysiology and treatment.

Arthritis, Rheumatoid↗
PubMed1989

Pharmacological actions and clinical use of fructus schizandrae.

Fructus Schizandrae (FS) is a well-known Chinese herb which has been widely used in ancient China. During recent decades, it has been found to be effective in viral and chemical induced hepatitis. In this paper, we report the studies on the chemical constituents and pharmacological actions of FS on mice liver. The results indicated that FS and its several components can mainly protect liver from injury induced by toxic substances such as CCl4; they have anti-oxidant activities against oxygen free radicals; FS and four components have inducing action on liver cytochrome P-450; they also promote certain anabolic metabolism such as serum protein biosynthesis and glycogenesis. All these activities would be of importance in the protection and repair of the injured liver cells. The clinical use of FS is also presented.

Animals↗
PubMed1989

[Mechanism of the protective action of kopsinine against hepatotoxicity of carbon tetrachloride].

Kopsinine 1 mmol/L inhibited microsomal lipid peroxidation (MDA) formation induced by CCl4 in vitro. Metyrapone, a specific inhibitor of cytochrome P-450, partially counteracted the inhibitory effect of kopsinine on MDA formation. Oral administration of kopsinine 200 mg/kg decreased the formation of diene conjugates in liver microsomes in CCl4 (1 ml/kg ig) intoxicated mice. Kopsinine also inhibited 14CCl4 covalent binding to lipids and proteins of liver microsomes. But the degree of inhibition was not as pronounced as that of inhibition of MDA. The metabolic conversion of CCl4 to carbon monoxide and the utilization of NADPH in the course of CCl4 metabolism by liver microsomes were increased by kopsinine in intro. It appears that to maintain the stability of membranes of liver cells is the mode of the protective action of kopsinine.

Alkaloids↗
PubMed1989

[Action of schizandrin B, an antioxidant, on lipid peroxidation in primary cultured hepatocytes].

The action of schizandrin B (Sin B) was observed in freshly isolated hepatocytes damaged by FeSO4/cysteine and CCl4. Two types of free radicals, .OH and .CCl3, generated from FeSO4/cysteine and CCl4, respectively, induced lipid peroxidation in hepatocytes. It was found that the speed of lipid peroxidation (MDA production) and the degree of alteration in hepatocyte morphology were closely related to the type of free radicals. MDA production and membrane protrusion of hepatocytes injuries by FeSO4/cysteine were faster and more severe than those observed with CCl4. Sin B was shown to decrease the production of MDA and the release of GPT and LDH, and to increase hepatocyte viability as well as maintaining the integrity of the hepatocyte membrane surface. These actions of Sin B were stronger than vitamin E at the same concentration. It was observed that no inhibitory effect of phenobarbital, a typical inducer of cytochrome P-450, as Sin B induced liver cytochrome P-450, on MDA production in hepatocytes damaged by FeSO4/cysteine. The results suggest that Sin B possesses antioxidant activity.

Animals↗
PubMed1989

[Protective action of kopsinine F against experimental liver injury in mice].

Kopsinine F is an indole alkaloid. The present studies show that prior oral administration of kopsinine F 150 mg/kg significantly protected mice from liver injuries induced by intraperitoneal injection of CCl4, thioacetamide and acetaminophen. The alkaloid also inhibited CCl4 induced lipid peroxidation (MDA formation) of liver microsomes and 14CCl4 covalent binding to lipids of liver microsomes in vitro. In addition, kopsinine F significanty induced hepatic microsomal cytochrome P-450 in mice. The results indicate that kopsinine F has hpatoeprotective activity in mice.

Acetaminophen↗
PubMed1989

[Protective action of kopsinine against experimental liver injuries in mice].

Kopsinine is an indole alkaloid. Kopsinine 200 mg/kg is significantly protected mice from liver injury induced by CCl4, paracetamol, thioacetamide and prednisolone. The elevated serum transaminase levels and liver lesions were reduced by kopsinine. In addition, kopsinine markedly promoted liver regeneration and the incorporation of [3H]TdR and [3H]leucine into liver protein and DNA, respectively, in partially hepatectomized mice. The results indicate that kopsinine has a hepatoprotective action in mice.

Alkaloids↗