[Treatment of torsade des pointes by intravenous magnesium]. / Traitement des torsades de pointes par magnésium intraveineux.

A 72 year old woman was admitted with decompensation of a hypertensive cardiopathy and treated with diuretics. She developed recurrent syncopal torsades de pointes during the 24th hour which were reduced by a bolus intravenous injection of 3 g of magnesium sulphate (Mg SO4). There was a recurrence 30 minutes later which regressed after a second injection of 3 g of Mg SO4. A continuous intravenous infusion of 18 g/day of Mg SO4 prevented further recurrences of the arrhythmia. Biochemical analysis showed intra and extracellular magnesium deficiency at the time of the torsades de pointes but the intracellular potassium was normal. The QT interval was prolonged but this parameter did not change after the bolus of Mg SO4. It returned to normal progressively afterwards. The clinical course was uncomplicated with no recurrences. Metabolic correction was obtained in 3 days. This observation raises the question of the mechanisms relating diuretic therapy, magnesium and torsades de pointes.

[Estimation of aluminium in biological fluids by atomic absorption spectrophotometry in a graphite oven (author's transl)]. / Dosage de l'aluminium dans les liquides biologiques par spectrophotométrie d'absorption atomique en four graphite.

The possibilities of use of a graphite oven type HGA 74 (Perkin Elmer) for the estimation of aluminium in biological fluids by atomic absorption spectrophotometry are described, with a special study of the stages of drying, mineralisation, atomisation, flow of inert gas, requirement for correction of non-specific absorption, etc. Under fixed experimental conditions, the limit of sensitivity (absorption 1%) was 2.28.10.(-11) grams and the linearity was good up to 100 microgram/l. This method of analysis by direct treatment of the samples required only small volumes of the latter and reduces the risk of contamination.

[Methods of determination of selenium in biological matter]. / Méthodes de dosage du sélénium dans les milieux biologiques.

Main techniques used: graphite furnace atomic absorption direct or after preliminary treatment of the sample, graphite furnace atomic absorption by generation of hydrides, fluorometry, gaz chromatography, differential pulse voltammetry. The various quality criteria of these methods are compared as well as the usual values in the different biological fluids (whole blood, plasma, serum, erythrocytes, urine).

[The antibacterial activity of amniotic fluid with a correlation between zinc phosphorus concentrations (author's transl)]. / Activité antibactérienne du liquide amniotique corrélation avec la zincamnie et la phosphoramnie.

Antibacterial activity of 22 amniotic fluids collected at different stage of pregnancy have been tested against different types of staphylococci: 209 P, 2961 and Escherichia Coli OMS and 83. At the same time zinc and phosphorus concentration in these fluids have been measured. 77 p. 100 of those fluids present an antibacterial activity, but no correlation has been found with their concentration in zinc and phosphorus. Probably this activity is multifactorial and further studies need to be done to identify the factor or factors responsible for that antibacterial activity.

[Free radicals derived from oxygen and lipid peroxidation. Role in cellular biology and physiopathology]. / Les radicaux libres dérivés de l'oxygène et la peroxydation lipidique. Rôle en biologie cellulaire et en physiopathologie.

Lipid peroxidation results from the attack of membrane phospholipids by free radicals derived from oxygen. It plays a major role in normal cell life processes. Under physiological conditions, this attack is modulated by an enzymatic system (superoxide dismutase, catalase, glutathione peroxidase) and by a non-enzymatic system (vitamin E and others). Many pathological processes might be explained by a deficient protection system or by an imbalance between attack and protection. Lipid peroxidation is difficult to detect and measure, and the methods available still have low sensitivity.

[Copper, zinc and aluminum contamination of blood specimens used for determination of these metals]. / Contamination par le cuivre, le zinc ou l'aluminium des prélèvements sanguins destinés au dosage de ces métaux.

Increasing interest and demand in determinations of copper, zinc and aluminium in clinical biochemistry, led us to pay particular attention to problems of blood collection. We tested several blood collecting tubes for contamination by these metals. Evacuated tubes must be avoided; polystyrene and polypropylene tubes are apparently the least polluting. However, strict rules cannot be made, and each biochemist should test the blood collecting devices he wants to use for trace elements analysis.

[Lipid peroxidation and free radicals. Role in cellular biology and pathology]. / Lipidoperoxydation et radicaux libres. Rôle en biologie cellulaire et en pathologie.

Membrane phospholipids attack by oxygen free radicals, i.e. lipidoperoxidation, occurs in normal cellular life. This free radicals attack is controlled by a protective system, both enzymatic (superoxide dismutase, catalase, glutahione peroxidase) and non enzymatic (vitamine E). Imbalance between attack and defense can explain many pathological events. In these events, the oxidation products of unsaturated fatty acids are of fundamental importance, in particular those derived from arachidonic acid (prostaglandins, prostacyclins, thromboxanes and leukotrienes).

Evaluation of acid phosphatase isoenzymes in seminal fluid from normozoospermic, oligozoospermic, azoospermic and asthenoteratozoospermic men.

Acid phosphatase was measured in the semen of normozoospermic, oligozoospermic, azoospermic and asthenoteratozoospermic men: there was no significant difference between oligozoospermic and control groups whereas we observed an increase in enzyme levels in the azoospermic group and a reduction in the asthenoteratozoospermic subjects. Furthermore, an isoelectric focusing method for the separation of isoenzymes was developed. Only prostatic isoenzymes 2 and 4 were found in semen. Isoenzyme 2 sialylation profile was determined in the four groups. The sperm count did not influence this profile. These findings are discussed.

[Serum zinc and copper in hypercholesterolemia]. / Zinc et cuivre sériques dans l'hypercholestérolémie.

For some authors, absolute or relative copper deficiency, with an elevated plasmatic zinc/copper ratio, could be a risk factor in the etiology of cardiovascular diseases by altering lipid metabolism. Animal or human studies carried out with zinc and/or copper supplemented or deficient diets on biochemical lipid parameters, led to inconsistent results. Nevertheless, no study was already done in hypercholesterolemic patients, concerning possible correlation between serum levels of these trace elements and cholesterol, HDL cholesterol and apolipoprotein B blood levels. 67 patients were distributed in three groups according to their hypercholesterolemia. The serum copper concentration was elevated, serum zinc concentration and zinc/copper ratio were decreased in the hypercholesterolemic group (cholesterol greater than 7.7 mmol/l). Serum zinc, copper and zinc/copper ratio were significantly correlated with HDL cholesterol (respectively r = + 0.56 p less than 0.05, r = - 0.68 p less than 0.01, r = + 0.76 p less than 0.001).

[Effect on serum aluminium levels of continued ingestion of aluminium gels by patients with chronic renal insufficiency (author's transl)]. / Influence de la prise prolongée de gels d'alumine sur les taux sériques d'aluminium chez les patients atteints d'insuffisance rénale chronique.

Atomic spectrometric absorption without flame allows reliable determination of serum aluminium levels (S.A.). Serum level in 59 normal subjects taking no aluminium gel (A.G.) is 24.3 +/- 8.4 microgram/l. Similar value were observed in 27 patients with renal insufficiency even severe who do not take A.G. Mild elevation of S.A. (40 +/- 12 microgram/l) was observed in 21 dialysed patients receiving no A.G. S.A. elevation is related to the aluminium content of dialysis fluid. A.G. intake in patients with renal insufficiency is followed by increase of S.A. The levels increase in relation with the daily dose of A.G. The highest values are observed among dialysed patients. In 41 dialysed cases A.S. values are between 70 and 600 microgram/l. In 17 patients dialysed for a mean period of 47 months mean serum A.S. is 165 +/- 40 microgram/l. The precise role of aluminium intoxication in the genesis of the dialysis encephalopathy syndrom remains controversial. From a clinical point of view aluminium intoxication should be looked for in any patient with encephalopathy who is taking aluminium gels and/or who is dialysed.

[Plasma zinc levels in elderly hospitalized subjects. Correlation with other nutritional and immunological markers and survival]. / Le zinc plasmatique chez le sujet âgé institutionnalisé. Corrélations avec d'autres marqueurs nutritionnels, immunologiques et la survie.

Plasma zinc levels were measured in 95 elderly patients hospitalized in a long stay unit and in 100 healthy controls under 65 years of age. Plasma zinc concentrations were significantly lower in the elderly patients, as compared to the younger subjects (p 0.001). The correlations with serum prealbumin (p 0.05) and serum albumin (p 0.05) concentrations and the frequent association with protein-calorie malnutrition suggest that the low serum zinc levels mirror a low dietary zinc intake. Immunological tests in the elderly show moderate lymphopenia, high serum IgA and frequent depression of delayed cutaneous hypersensitivity to DNCB and PHA. We find a significant correlation between plasma zinc concentration and peripheral blood lymphocyte counts, but not the other immunological parameters. Linear discriminant analysis shows that the association of low plasma zinc values, low serum protein concentration and high serum IgG concentration implies poor prognosis.

Serum concentration and peritoneal transfer of aluminum during treatment by continuous ambulatory peritoneal dialysis.

The evolution of the aluminum (A1) serum levels during a 2-year follow-up and the peritoneal transfer of A1 were studied in 22 patients treated by continuous ambulatory peritoneal dialysis (CAPD), using a dialysate with a very low A1 concentration (r = 0.25 - 0.30 mumoles/liter). Patients were divided in three groups. A transfer of A1 from the patient to the dialysate was observed in all patients. In group 1, patients exclusively treated by CAPD and who have never received aluminum-containing phosphate binders (ACPB), mean level (+/- SD) of serum A1 stabilized within a safe range (0.60 +/- 0.28 mumoles/liter). In group 2 the oral administration of ACPB in patients exclusively treated by CAPD induced a slow and progressive increase of A1 serum concentration despite the increase of the A1 excretion through the peritoneal route. In group 3, patients previously treated by hemodialysis and receiving ACPB, the high serum A1 levels observed before treatment by CAPD decreased rapidly on CAPD. A1 removal through the peritoneum was higher in group 3 than in group 2 despite serum A1 levels not statistically different in both groups. A1 removal through the peritoneum is mainly influenced by serum and dialysate A1 concentration. A1 body stores could play a role in the transfer of A1 through the peritoneum. Three cases of A1 poisoning due to the accidental use of a dialysate with a high A1 content are reported.

Acid phosphatase and zinc in semen of subjects with no clinical evidence of prostatic disease.

We evaluated the distribution of values for prostatic acid phosphatase (EC 3.1.3.2) activity and zinc concentration in semen of 80 men without clinical evidence of prostatic disease. Both substances have log normal distributions. Reference intervals were defined by parametric tests after logarithmic transformation of data and by nonparametric tests. There is a correlation between zinc concentration and prostatic acid phosphatase activity in semen.

Kinetics of allopurinol and oxipurinol after chronic oral administration. Interaction with benzbromarone.

Previous studies have described a pharmacokinetic interaction between probenecid, a uricosuric drug, and oxipurinol, the major metabolite of allopurinol. In single dose studies, no interaction was found to occur between benzbromarone, another uricosuric agent, and oxipurinol. A cross over study was conducted in 12 volunteers to compare the kinetics of allopurinol and oxipurinol following treatment for 7 days with allopurinol alone or combined with benzbromarone 20 or 100 mg. The pharmacokinetic parameters of allopurinol were not modified by the uricosuric therapy, but those of oxipurinol were markedly altered by concurrent administration even of the lower dose of benzbromarone; the average plasma level fell by 30% and the renal elimination rate was increased by 50%. A parallel increase in the renal elimination rate of uric acid was observed (significant only with the higher dose of benzbromarone) and a positive linear correlation between the fractional excretion of uric acid and that of oxipurinol was established.