Anoxic photodamage in the presence of porphyrins: evidence for the lack of effects on mitochondrial membranes.
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Biomedical subjects
Publications and source records attributed to D Brault.
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Xanthine-oxidase deficiency should be suspected whenever hypouricaemia coexists with hypouricuria and hyperoxypurinuria. In 18 months. Two new cases of xanthinuria were detected by routine urinary oxypurine assay among 10,000 patients where uricaemia was systematically tested. The xanthine-oxidase deficiency was associated with Hodgkin's disease in one case and with uncomplicated pregnancy in the other.
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The glucose tolerance and serum lipids pattern were studied in 20 hemodialyzed patients after 8 and 12 hours of fasting. They all were non-obese uremics under 40 years of age. The test was conducted according to the nutritional conditions of the protocol of de Gennes. Fasting hyperglycemia and an abnormal glucose tolerance test were observed in 75% of the patients. The basal serum insulin levels were increased in 80% of the cases. 40% of the population studied exhibited significant hypertriglyceridemia after 12 hours and 65% after only 8 hours of fasting. Thus, this protocol was useful for detecting abnormalities in the metabolism of triglycerides in hemodialyzed patients with few baseline disturbances. The normal levels of serum triglycerides at 12 hours could be explained by 1) the relatively young age of the population studied and 2) dialysis with glucose free solutions.
Two successive pregnancies were observed in a patient with xanthinuria. In each of them, maternal serum uric acid (SUA) level rose progressively during the third trimester, reaching a subnormal value just before delivery. The level of UA was slightly higher in arterial cord blood than in maternal blood. There was no difference between levels in arterial and venous cord blood. It is suggested that xanthine oxydase may be present in the placenta.
The glucose tolerance and serum lipids pattern were studied in 20 hemodialyzed patients after 8 and 12 hours of fasting. They all were non-obese uremics under 40 years of age. The test was conducted according to the nutritional conditions of the protocol of de Gennes. Fasting hyperglycemia and an abnormal glucose tolerance test were observed in 75% of the patients. The basal serum insulin levels were increased in 80% of the cases. 40% of the population studied exhibited significant hypertriglyceridemia after 12 hours and 65% after only 8 hours of fasting. Thus, this protocol was useful for detecting abnormalities in the metabolism of triglycerides in hemodialized patients with few baseline disturbances. The normal levels of serum tryglycerides at 12 hours could be explained by 1) the relatively young age of the population studied and 2) dialysis with glucose free solutions.
The proposed technic is a rapid method of measurement of acetatemia by simple deproteinisation of plasma, then analysis by gas chromatography. The plasma is routinely saturated with acetate in formic acid solution in order to permit greater sensitivity of reading of usual or subnormal concentrations. The chromatography column is filled with chromosorb WAW impregnated with 15 per cent didecyl phtalate and 2 per cent phosphoric acid. The stationary phase of intermediate polarity permitting satisfactory stability of the chromatograms.
A technique of anesthesia is considered for laryngoscopy in suspension, and certain acts of surgery of the vocal cords, e.g. myxoma, and of the trachea, e.g. destruction of papillomatosis. The patient is in apnea, unventilated, a catheter brings down to the level of the carena a current of oxygen of 15 liters per minute, the gaseous acidosis is buffered by injections of a solution of molar sodium bicarbonate. After briefly recalling the notions which justify this technique, its repercussion on homeostasis is studied by arterial gasometry. General anaesthesia with apneic oxygenation may offer the ENT surgeon increased possibilities of exploration and operation at the level of the larynx and trachea, but owing to its biological consequences, it should be used only with circumspection and its indications should be totally justified, for acts of limited duration. The technique seems, at present, difficult to adapt to surgery with laser.
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The toxicity of halogenated alkanes originates from their metabolism by cytochrome P-450 which leads to the formation of reactive intermediates. In particular, peroxyl radicals derived from the halogenated compounds are believed to induce peroxidative chain degradation of lipids. To examine this hypothesis, radical reactions in a system involving FeIII-deuteroporphyrin as a model of cytochrome P-450, fatty acids or cholesterol, and carbon tetrachloride or the anesthetic agent halothane are studied by means of pulse radiolysis. It is shown that haloperoxyl radicals react with the fatty acids in competition with their reaction with the ferriporphyrin. Moreover, the secondary fatty acid peroxyl radicals also react efficiently with the porphyrin. A model for halogenated alkane toxicity is discussed in terms of these new findings. The importance of local oxygen concentration and structural arrangement of fatty acids around cytochrome P-450 are emphasized.