Treatment of washed human erythrocytes for a short time (up to 2h) with 75 or 100mM 2, 2′-azo-bis(2-amidinopropane) dihydrochloride (AAPH), a water-soluble, radical-forming oxidant, induced considerable oxidation of the membrane protein SH groups, without any detectable formation of lipid peroxide from the membrane lipid. These cells became susceptible to the action of pancreatic phospholipase A2, and the asymmetric distribution of their membrane aminophospholipids was partially lost, accompanied by a reduced activity of the aminophospholipid translocase of the membrane. In contrast, treatment of the erythrocytes with t-butylhydroperoxide (t-BHP), a lipid-soluble, radicalforming oxidant, caused rapid and intensive lipid peroxidation, but SH oxidation to a lesser extent than that achieved by AAPH. In these cells, the membrane phospholipid asymmetry was well maintained, although the aminophospholipid translocase activity was reduced. These results suggest that AAPH might oxidize both the aminophospholipid trans-locase of the membrane and the membrane skeletal proteins responsible for maintenance of the asymmetric phospholipid distribution, resulting in loss of the asymmetry, and that t-BHP causes formation of peroxides from the membrane phospholipids, which might affect aminophospholipid translocase only.
We developed a new approach to the treatment of malignant glioma by intracellular production of human β-interferon (HuIFN-β). In our previous study [Mizuno, M., et al. (1990): Cancer Res., 50, 7826-7829], we could inhibit the growth of cultured glioma cells by transfecting them with the HuIFN-β gene by means of novel liposomes bearing a monoclonal antibody against a glioma-associated surface antigen. To kill the cells, however, some further device was needed. In the present study, we found by in vitro experimentation that production of HuIFN-β in the cells transfected with the gene could be increased by treatment of the cells with tumor necrosis factor-α (TNF-α) prior to the transfection and that the cells completely disappeared by 9 days after the transfection. Human glioma subcutaneously transplanted into nude mice could be killed completely if the mice were given TNF-α prior to the gene transfection. Thus the gate to gene therapy for brain tumors has been opened.
Dietary fat is known to influence the activities of various membrane-bound enzymes. The impact of various commonly consumed vegetable fats of India, viz., groundnut, coconut, safflower or mustard oil with varied fatty acid composition on the activities of liver microsomal membrane-bound enzymes and microsomal lipid composition was studied. In a feeding experiment, male weanling rats were fed these oils at 20g per 100g of the diet for 4 months. Liver microsomal cytochrome P-450 content was found to be significantly higher in the safflower oil-fed group and lowest in the coconut- and mustard oil-fed groups. The activity of UDP-glucuronyltransferase was highest in the mustard oil- and safflower oil-fed groups and lowest in the coconut oil-fed group and intermediary in the groundnut oil-fed group. The activity of Mg2+-ATPase was markedly lower in the safflower oil-fed group than in the rest of the groups. Na+, K+-ATPase activity was distinctly higher in the mustard oil-fed group, while Mg2+-ATPase activity was markedly higher in the groundnut oil-fed group. Further, the liver microsomes of safflower oil and mustard oil-fed groups showed higher amounts of cholesterol and phospholipids than the other two groups. However, the safflower oil group showed a higher cholesterol to phospholipid molar ratio than the other groups. Changes in cholesterol to phospholipid molar ratio as well as in fatty acid composition of the microsomal membranes could be responsible for the differences in the activities of the enzymes observed in the different groups.
The developmental mechanism of the bone disorder induced by biotin deficiency was studied in osteogenic disorder rats, animals that have a hereditary defect in ascorbic acid-synthesizing ability. The osteogenic disorder rats fed a biotin-deficient diet containing raw egg white were afflicted with bone abnormality including a hunch in the vertebral column. In the case of biotin deficiency, although the ascorbic acid content in the diet was in excess of the required amount, ascorbic acid levels of the plasma and the organs in the rats were significant lower than those of control rats. This suggests that the bone disorder induced by biotin deficiency in the rats may result from the promotion of ascorbic acid consumption or the impairment of ascorbic acid incorporation in the animal tissues.
We examined the anti-tumor capacity and alterations of glutamine metabolism in tumor-bearing rats by administering a combination of a glutamine antagonist and total parenteral nutrition with an imbalanced solution of amino acids. Rats inoculated with Yoshida sarcoma were divided into two groups: group I (n=11) received a solution enriched in branched-chain amino acids, while group II (n=10) was deprived of non-essential amino acids. Both groups received a glutamine antagonist (6-diazo-5-oxo-L-norleucine) given 7 days after tumor inoculation. Tumor weight in group II was significantly lower than that in group I. The relationship between tumor weight and levels of free amino acids in tumor tissue showed a negative correlation with many amino acids, with the highest observed for glutamine. And this correlation was apparent in group II, but not in group I, suggesting that glutamine utilization by the tumor was inhibited to a greater extent in group II. These data suggest that complete inhibition of glutamine utilization by Yoshida sarcoma may lead to a marked reduction in tumor growth, because of its characteristic dependence on glutamine.
The inhibitory effect of γ-Oryzanol on liver cirrhosis induced by a high-fat diet in spontaneously hypertensive rats (SHRs) was investigated. Eight-week-old SHRs were fed a high-fat diet or a high-fat diet with γ-Oryzanol for 3 months, Lipogenic liver cirrhosis was induced in the animals fed the high-fat diet only. In contrast, supplementation of the diet with γ-Oryzanol suppressed liver cirrhosis and hyperlipidemia in the supplemented group. This study suggests that γ-Oryzanol is very effective against lipogenic liver cirrhosis in the SHR, an animal which possesses natural abnormalities in lipid metabolism.
We determined the changes in the sources of energy supply in biotin-deficient osteogenic disorder Shionogi rats. Plasma glucose level of biotin-deficient rats decreased gradually and steadily from the 59th day of the dietary regimen. Plasma insulin decreased sharply on day 59, although plasma glucose was still sufficient. Plasma insulin in response to an oral glucose load in the deficient rats was approximately one-third less in concentration than that of the control. The decrease in the insulin level may be induced by biotin deficiency in the early stage in the deficient rats. In the later stage of the deficiency period, when plasma glucose decreased to under 50% compared with the control level, the plasma non-esterified fatty acid level greatly increased. This suggests that the source of energy supply in the biotin-deficient rats changed from glucose to non-esterified fatty acid supplied by adipose tissue. The time of increase in the plasma non-esterified fatty acid level coincided with the onset of the clinical features of biotin deficiency in the rats.
Twenty inpatients suffering from diabetes mellitus were given prescribed therapeutic diets containing 1, 000-1, 500kcal/day and supplemented with 28mg zinc phosphate for 3 weeks. Twenty outpatients were untreated and were advised to consume specified diets. The results indicated good response for the inpatient group. Elevated levels for insulin and serum zinc were shown, which proved to be statistically significant. Blood glucose, glucagon, and glucose-6-phosphatase levels were reduced significantly due to the diet management and zinc supplementation, while calcium showed no difference. The control group did not show any significant difference in any parameter throughout the study. Our findings suggest that a controlled dietary regimen together with supplementation with zinc might be useful to suppress plasma glucose and to regulate insulin secretion of diabetics.