Co-localization of glucokinase with actin filaments.

A portion of glucokinase appeared to be co-localized with actin filaments in the cytoplasm of cultured rat hepatocytes incubated with 25 mM glucose. When liver- or islet-type glucokinase was transiently expressed in COS-7 cells, the expressed glucokinase was also co-localized with actin filaments in the cytoplasm of these transfected cells. Although co-localization of glucokinase with actin filaments was not clearly demonstrated in the pancreatic beta-cell line MIN6, islet glucokinase was found to be present in both the nucleus and the cytoplasm, though predominantly in the nucleus. These findings suggest that subcellular localization of glucokinase, including co-localization with actin filaments, may have an important physiological role in metabolic regulation.

Ca(2+)-ATPase activity in streptozotocin-induced diabetic rat kidneys.

Kidney Ca(2+)-ATPase activity was altered in streptozotocin (STZ)-induced diabetic rats. Male rats, 200-250 g, were rendered diabetic by injection of STZ 45 mg/kg body weight via the tail vein. Following injection, control rats and diabetic rats at 1, 4, 8 or 15 weeks were sacrificed. Kidney tissues were obtained for the isolation of Ca(2+)-ATPase. Ca(2+)-ATPase activity was determined spectrophotometrically. Total calcium was measured by atomic absorption spectrophotometry. Diabetic rats had significantly elevated blood glucose levels compared to controls. Blood glucose levels were 92.92 +/- 1.215 mg/dl (mean +/- S.E.M.) for the control group, and 362.50 +/- 9.613 mg/dl at one week and > 500 mg/dl at 4, 8 and 15 weeks of diabetes. Enzyme activities were significantly higher at 4, 8 and 15 weeks of diabetes than in the control group (p < 0.001). There was no significant increase at one week of diabetes. Ca(2+)-ATPase activity was 0.43 +/- 0.003 U/L, 0.517 +/- 0.058 U/L, 0.707 +/- 0.078 U/L, 0.730 +/- 0.006 U/L and 0.715 +/- 0.055 U/L respectively for controls and rats at 1, 4, 8 and 15 weeks of diabetes. Calcium levels in diabetic rat kidneys were also significantly higher than for controls. The increase in enzyme activity may have been caused by higher calcium levels in diabetic kidneys resulting from a compensatory response of the enzyme to high levels of the ion.

In vitro effects of an azo compound on the haemolysis and unsaturated fatty acids of red blood cells.

Human red blood cells were treated with 4,4'-azo-bis-(4-cyanovaleric acid) (0-27 x 10(-3) M) in order to determine the effect of the compound on red blood cell haemolysis and unsaturated fatty acids. Maximum haemolysis amounting to approximately 100%, occurred after 60 min incubation with 15 x 10(-3) M azo compound and did not change to any significant extent by increasing incubation time to 4 h. The azo compound caused a decrease in unsaturated fatty acids unrelated to the number of double bonds. The percentage loss of unsaturated fatty acids was 60-100. Therefore the present study reveals that incubation of red blood cells with 15 x 10(-3) M 4,4'-azo-bis-(4-cyanovaleric acid) for 1 h causes maximum haemolysis. Also the damaging effect of the compound on red blood cell unsaturated fatty acids is parallel to haemolysis. These results show that this compound might have relevance for pathophysiology of red blood cells.

Effect of vitamin C on copper and iron status in men and guinea pigs.

Healthy individual were given 2 g of vitamin C per day for 2 months. Whole blood iron, ascorbic acid, hemoglobin, and serum ceruloplasmin were determined at the beginning, and 1 or 2 months after the start of the experiment. The concentration of ascorbic acid was observed to increase significantly in the blood, while blood iron, hemoglobin, and serum ceruloplasmin levels significantly increased at the end of the 1st month, but decreased to control levels at the end of the 2nd month. Male albino guinea pigs were administered 8, 180, and 360 mg of vitamin C per day for 2 months. Liver ferritin iron, liver copper, serum copper, and serum ceruloplasmin levels significantly decreased, but there was no significant change in hemosiderin iron while blood ascorbic acid significantly increased at the end of the 2 month period. There was no significant change in serum iron and hematocrit levels. These results suggest that vitamin C has an antagonistic effect on copper metabolism in guinea pigs but not in humans either on copper or iron metabolisms.

Permeability of latex gloves after exposure to 6 chemical agents.

OBJECTIVES: To assess the effects of exposure to 6 chemical agents on the permeability of latex gloves by dye permeability test and to qualitatively evaluate the microscopic changes in the ultrastructure of the gloves. METHOD AND MATERIALS: The middle fingers of 35 medium-sized, nonsterile latex gloves were used. The chemical agents tested were eugenol, 5% NaOCl, 17% EDTA, 0.2% chlorhexidine gluconate, Cresophene (Septodent), and Chlorispray (Anios). Following treatment for 15 minutes with each chemical agent, glove fingers were filled with 10 mL of 0.02% erythrosine dye solution. Then the outer glove surface was washed with 10 mL of distilled water at intervals of 15, 30, 45, and 60 minutes. A spectrophotometer was used at 530-nm wavelength to determine the percentage of absorption from each collected washing solution. The results were compared with the values obtained from untreated gloves. Additionally, small pieces of the glove samples were examined by SEM to determine whether any ultrastructural changes occurred upon exposure to the chemicals. RESULTS: The permeability of gloves was increased by exposure to Chlorispray and Cresophene, but 5% NaOCl, 17% EDTA, and 0.2% chlorhexidine gluconate had no effect. Major surface changes were noticed in NaOCl, EDTA, Cresophene, and Chlorispray groups, while eugenol and chlorhexidine gluconate had minimal or no effect. CONCLUSION: Damaging effects of chemical agents on latex gloves for penetration and infection control should be considered by the dental practitioner.

Oxidation of human red blood cells by a free radical initiator and effects of radical scavengers.

Haemolysis induced by a free radical initiator (4,4'azobis-(4-cyanovaleric acid) has been studied with transfusion blood. Azobis cyanovaleric acid caused an increase in haemolysis. The effect of alpha- and gamma-tocopherol, 2,2,5,7,8 pentamethyl-6-chromanol and 2,2,7,8 tetramethyl-6-chromanol on the red blood cell haemolysis was studied. There was little difference in the antioxidant action of four chromanols studied. Compounds without the side chain appeared to suppress haemolysis as well as alpha- and gamma-tocopherol. These results suggest that the long side chain of vitamin E has little or no effect on its antioxidant activity in red blood cells. However "protection against haemolysis" was related to total chromanol content of red blood cells. Therefore by dividing "protection" by "total chromanol content" it can be seen that alpha-tocopherol has the highest antioxidant potency.

Fatty acids in plasma and red blood cell membranes in humans, rats, rabbits and dogs.

Fatty acids were estimated in plasma and red blood cell membrane in rats, rabbits, dogs and humans. The fatty acid pattern of plasma and red blood cell membrane was similar in all species and humans with little exceptions. C18:2 was higher in plasma than red blood cell membrane whereas C20:4 was higher in red blood cell membrane than plasma except rabbit. C18:2 was high in rabbit red blood cell membrane when compared to others. Dog was exceptionally very low in C18:2 and high in C20:4 in red blood cell membrane whereas rabbit was low in C20:4 and high in C18:2. 22-Carbon fatty acids showed some variation. Among 22-carbon fatty acids C22:6 was found highest in human red blood cell membrane, with quite high amounts in rat and rabbit but not in dog. Rats were closest to human in their fatty acid patterns.

Determination of Ca2+-atpase activity in streptozotocin-induced diabetic rat liver.

Microsomal Ca2+-ATPase activity was studied in control and streptozotocin (STZ)-induced diabetic rat livers. Male rats were rendered diabetic by injection of STZ (45 mg/kg body weight) via the tail vein. Diabetic rats at 1, 4, 8, 10 or 15 wk and control rats were sacrificed. Liver tissues were obtained for the isolation of Ca2+-ATPase. Ca2+-ATPase activity was determined spectrophotometrically and lipid peroxidation [measured as tiobarbituric acid reactive substances (TBARS)] in liver tissues was determined spectrofluorometrically. Total calcium was measured by atomic absorption spectrophotometry. Blood glucose levels of the diabetic animals were >500 mg/dl at 4, 8, 10 and 15 wk of diabetes. Ca2+-ATPase activity was significantly decreased at all weeks of diabetes compared to control group (p<0.001). Ca2+-ATPase activity of control rats was 0.193 +/- 0.015 U/I whereas activity was 0.130 +/- 0.015 U/I at 15 wk of diabetes. The difference in calcium levels of diabetic rat livers was not significantly different compared to control group. On the other hand TBARS were elevated by 67% at 15 wk of diabetes. The decrease in enzyme activity may have been caused by elevated TBARS levels observed in liver tissue sindicative of increased lipid peroxidation.

The inhibitory effect of benzodiazepine derivatives on the bovine lens aldose reductase enzyme.

The aldose reductase enzyme, involved in the sorbitol pathway which is an important mechanism in regulation of mammalian glucose metabolism, has been known to play a significant role in the initiation of diabetic complications. Numerous chemical substances have been prepared in order to improve the pharmacological profile of inhibition of aldose reductase enzyme. In this study, aldose reductase inhibitory activities of several benzodiazepine derivatives were investigated. The enzyme was obtained from bovine lenses via the ammonium sulphate-protein cut method with several steps. It was found that tetrazepam had a significant inhibitor potency among the other benzodiazepine derivatives showing very slight inhibitor activities that are indicated in terms of percent inhibitor potency at 10(-4) M concentration.