Areekul S

Catalase Activity in Red Cell and Liver of Mice Infected with Plasmodium Berghei

Hydrogen peroxide (H2O2) has been incriminated to have an oxidative killing malaria parasite. As P. berghei-infected mouse red cells generated H2O2 in vivo, this would result in the alteration of catalase status of the host. The present study was undertaken to determine catalase activity in red cells and liver of mice infected with P. berghei. The studies were performed in 17 samples of infected red cells as well as 20 samples of the normal red cells. Results showed that the catalase activity in red cells of the infected group was significantly lower (p less than 0.01) than that of the normal group. There was a reverse relationship between catalase activity and parasitemia. Crude parasite lysates possessed no catalase activity. Liver catalase content in the infected group was also found to be significantly lower (p less than 0.05) than that of the control group. All these findings indicated that P. berghei-infected mice caused a depressed catalase activity in red cells and liver which was possibly due to the catalatic function in detoxifying the increased H2O2 to water and free oxygen.

Homocysteine, Mthfr C677 T, Vitamin B12, and Folate Levels in Thai Children With Ischemic Stroke: A Case-control Study

Hyperhomocysteinemia has been identified as a risk factor for venous and arterial thrombosis especially in adult populations. Twenty-eight patients with an initial diagnosis of ischemic stroke and 100 controls, aged ≤18 years, were enrolled in this study. The mean plasma total homocysteine (tHcy) levels in patients and controls were significantly different with values of 8.7±3.6 and 7.5±2.4 μmol/L, respectively (P=0.01). The plasma tHcy at the 95th percentile was 11.5 μmol/L and patients whose plasma tHcy was above the 95th percentile had an odds ratio of 8.2 (95% confidence interval 1.4-47.2, P=0.02) for developing ischemic stroke. The genetic and acquired factors that could have affected plasma tHcy levels were studied and no differences were found between patients and controls. Factors that were investigated were vitamin B12, red blood cell folate, and serum folate levels as well as methylenetetrahydrofolate reductase C677T polymorphism. It is of note, however, that subjects whose plasma tHcy was above the 95th percentile had significantly lower serum folate levels (P=0.02).

Studies on the transcapillary escape rate of albumin and capillary permeability in rhesus monkeys infected with Plasmodium knowlesi

The transcapillary escape rate and plasma clearance rate of albumin were studied in five rhesus monkeys infected with Plasmodium knowlesi in comparison with six control monkeys by using 125I-HSA as a tracer. The plasma disappearance curve of the radioactivity was followed during the first 60 minutes after injection of this labelled protein. Plasma volume was found to be significantly higher while plasma albumin concentration was significantly lower, which resulted in the non-significantly increased intravascular albumin mass in the infected group. The mean values of the transcapillary escape rate, plasma clearance rate and the outflux of albumin from the intravascular to the extravascular compartments in the infected group were found to be significantly higher than those of the control group. This indicated that there was an increased leakage of plasma albumin from the circulation into the extravascular space in rhesus monkeys infected with P. knowlesi. As both capillary effective pore area per unit path length available for restricted diffusion and the specific permeability coefficient of plasma albumin were found to be significantly increased in the infected group, therefore the increased leakage of albumin was probably due to the increased surface of capillary membrane.