This study investigated the effect of cacao liquor extract (CLE) on tumor marker enzymes--alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), glutathione-S-transferase (GST), and glutathione reductase (GR) activities--in plasma and/or liver of hepatocarcinogenic rats, which were induced with diethylnitrosamine and 2-acetylaminofluorene. Twenty-nine male Sprague-Dawley rats (weighing 150-330 g) were divided into four groups (n = 6-8): normal control group (N), normal group + CLE (NE), cancer group (C), and cancer group + CLE (CE). Analysis of variance showed significant differences (P
The possible insecticide resistance mechanisms of four Malaysian field-collected strains of the German cockroach, Blattella germanica (Linnaeus) (Dictyoptera: Blattellidae), were characterized with biochemical assays and native polyacrylamide gel electrophoresis (PAGE). Elevated esterase activity (at low to moderate frequency) and altered acetylcholinesterase (low frequency) were detected in all field strains, while elevated glutathione S-transferase levels were present in only two strains. Seven esterase bands were separated by native PAGE; a greater intensity occurred in three bands in the resistant strains compared to the susceptible strain. Inhibition studies using specific inhibitors on polyacrylamide gels suggested that the slowest of these three esterases is a cholinesterase, while the other two are carboxylesterases with a preference for beta- over alpha-naphthyl acetate.
The effects of vitamin C and aloe vera gel extract supplementation on induced hepatocarcinogenesis in male Sprague-Dawley rats (120-150 g) by diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) was investigated. The severity of the carcinogenesis process was determined by measuring gamma-glutamyl transpeptidase (GGT) and the placental form of glutathione S-transferase (GSTP) histochemically in situ and in plasma and liver fractions. In addition, plasma alkaline phosphatase (ALP) and liver microsomal uridine diphosphate glucuronyl transferase (UDPGT) activity were also determined. Administration of DEN/AAF caused an increase in the surface area and number of enzyme-positive foci (both GGT and GSTP) compared with control. Supplementation of vitamin C or aloe vera gel extract to the cancer-induced rats suppressed this increase significantly (P < 0.05; P < 0.001). Increases in liver UDPGT, GGT, and GSTP activities were also observed with cancer induction that were again suppressed with either vitamin C or aloe vera gel supplementation. Plasma GGT in the DEN/AAF rats were determined monthly for the duration of the experiment and found to be reduced as early as 1 mo with aloe vera gel supplementation and 2 mo with vitamin C supplementation. In conclusion, vitamin C and aloe vera gel extract supplementation were found to be able to reduce the severity of chemical hepatocarcinogenesis.
Several xenobiotic metabolizing enzymes, including CYP1A1, NAT2 and GSTM1, are subject to genetic polymorphisms. Because these enzymes are important for the detoxification and/or bioactivation of drugs and carcinogens, these polymorphisms have important implications in therapeutics and cancer susceptibility. The distributions of CYP1A1, NAT2 and GSTM1 genotype frequencies in unrelated individuals of the Indian (n = 139) and Malay (n = 146) populations were characterized by the polymerase chain reaction. The respective allelic frequencies of wild-type and mutant alleles of CYP1A1 were 0.82 and 0.18 for the Indians, and 0.69 and 0.31 for the Malays. The frequencies of wild-type, M1, M2 and M3 of NAT2 among Indians were 0.44, 0.20, 0.32 and 0.04 respectively. The corresponding NAT2 allelic frequencies in Malays were 0.41, 0.12, 0.38 and 0.09. The GSTM1*A allele could not be amplified in 33.1% of Indians and 61.6% of Malays. At least one GSTM1*B allele was detected in 7.2% and 7.5% of the respective populations. The allelic frequencies of CYP1A1, NAT2 and GSTM1 among Malays are similar to previously reported frequencies among Chinese in the region. These findings will be of importance in the determination of cancer risks in these populations.
Comparative DDT-susceptibility status and glutathion s-transferase (GST) activity of Malaysian Anopheles maculatus, Culex quinquefasciatus and Aedes aegypti was investigated to ascertain the role of this enzyme in DDT resistance. The standardised WHO dose-mortality bioassay tests were used to determine DDT susceptibility in these mosquitos, whilst GST microassay (Brogdon and Barber, 1990) was conducted to measure the activity of this enzyme in mosquito homogenate. It appeared that DDT susceptibility status of Malaysian mosquitos was not correlated with GST activity.
The effects of ovariectomy and hormone replacement in control and carcinogen treated female rats were investigated by measuring whole blood and liver glutathione (WGSH, HGSH), glutathione S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GRx) and histological evaluation. Hepatocarcinogenesis was induced by diethylnitrosamine and 2-acetylaminofluorene. In control rats not receiving carcinogen, ovariectomy significantly increased the GST and GRx activities. Replacement with either estrogen or progesterone reduced the GST activities to below intact female values whereas replacement of both hormones together brought the GST activities to that of intact females. GRx activities were brought to intact female values by replacement with estrogen or progesterone, either singly or in combination. Neither ovariectomy nor sex hormone/s replacement influenced the levels of WGSH, HGSH and GPx activities. Carcinogen administration to intact rats increased all the parameters measured. Ovariectomized rats treated with carcinogen showed lower GPx and GRx activities at 2 mths. However, replacement with either progesterone or combined estrogen and progesterone increased GPx and GRx activities to original values. On the other hand GST and GPx activities in ovariectomized rats which had carcinogen treatment were lower than intact rats after 5 mths. Replacement with hormones either singly or both brought GST and GPx activities up to intact rat levels receiving carcinogen. The levels of WGSH, HGSH and GRx activities (5 mths) in carcinogen treated rats were not influenced by ovariectomy and/or hormone/s replacement. The results from this study suggested that ovariectomy reduced the severity of hepatocarcinogenesis which was restored by sex hormone/s replacement.
1. The effects of alpha-tocopherol and gamma-tocotrienol on glutathione S-transferase (GST) and gamma-glutamyl transpeptidase (gamma-GT) activities in cultured hepatocytes prepared from rats treated with diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) were investigated. 2. Both the alpha-tocopherol and gamma-tocotrienol treated hepatocytes showed significantly higher (P < 0.05) GST activities than untreated hepatocytes prepared from the carcinogen treated rats in the first 3 days of culture. Treatment with alpha-tocopherol and gamma-tocotrienol generally resulted in a tendency to increase the GST activities above that in the untreated hepatocytes. 3. Treatment with high doses (125-250 microM) of alpha-tocopherol and low doses (12.5-25 microM) of gamma-tocotrienol generally resulted in a significant reduction in gamma-GT activities at 1-3 days. gamma-GT activities are reduced as the dose of alpha-tocopherol and gamma-tocotrienol are increased.
1. The effect of tocotrienol and tocopherol on glutathione S-transferase (GST) and gamma-glutamyl transpeptidase (GGT) activities in cultured rat hepatocytes were investigated. 2. Tocotrienol and tocopherol significantly decreased GGT activities at 5 days in culture but tocotrienol also significantly decreased GGT activities at 1-2 days. 3. Tocotrienol and tocopherol treatment significantly decreased GST activities at 3 days compared to the control but tocotrienol also decreased GST activities at 1-3 days. 4. Tocotrienol showed a more pronounced effect at a dosage of greater than 50 microM tocotrienol at 1-3 days in culture compared to the control.
The effect of tocotrienol on the activities of glutathione S-transferases (GSTs), glutathione reductase (GR) and glutathione peroxidase (GPx) in rats given 2-acetylaminofluorene (AAF) was investigated over a 20 week period. Liver and kidney GST and liver GR activities were significantly increased after AAF administration. Kidney GPx activities were significantly affected; activity assayed with cumene hydroperoxide (cu-OOH) was increased but activity assayed with H2O2 was reduced. Supplementation of the diet with tocotrienol in the AAF-treated rats reduced the increase in enzyme activities. Tocotrienol on its own had no effect on the enzyme activities.
1. Toxicity evaluations of DDT, lindane, abate and carbaryl were carried out in the larvae of two wild Aedes aegypti strains from Kuala Lumpur and Klang. The Kuala Lumpur strain was more susceptible to the insecticides than the Klang strain. 2. The lethal toxicity time was also determined. The insecticides were found to take a longer time to exert their effect in the Klang strain as compared to the Kuala Lumpur strain. 3. Carboxylesterase activity was determined to be higher in the Kuala Lumpur strain, but glutathione transferase activities were higher in the Klang strain.
1. Glutathione transferases from the liver, lung and kidney tissues of the buffalo (Bubalus bubalis) and the Kedah-Kelantan cattle (Bos indicus) were partially purified by ammonium sulphate precipitation and Sephadex G-75 gel filtration. 2. Liver tissue contains the highest enzyme activity when compared to the lung and kidney tissues. 3. The activity in cattle is higher than that in the buffalo. 4. Isoelectric focusing separates the activities into the acidic, near neutral and basic fractions. 5. The focused patterns are different for each of the tissues and in each of the species investigated.