[Stability of alpha-tocopherol: pre-analytical conditions in its determination in blood samples]. / Stabilité de l'alpha-tocophérol: conditions préanalytiques à son dosage dans les prélèvements sanguins.

Incomplete and controversial data exist concerning vitamin E or alpha-tocopherol stability in biological samples. Recent clinical interest in the protective function of alpha-tocopherol provided another reason for the setting-up of a multicenter study by the Sociéte Française de Biologie Clinique. Our purpose was to examine the effects on alpha-tocopherol stability, firstly, of collection and transportation of blood samples, and, secondly, of the temperature (-20 degrees C and -80 degrees C) and period of storage of serum or plasma. alpha-tocopherol was determined in serum or plasma by isocratic liquid chromatography with UV detection at 292 nm. Our results established that alpha-tocopherol was extremely stable in blood, serum or plasma over 8 hours without special handling conditions (light, temperature). Pools of serum or plasma were stable for at least 3 months at -20 degrees C and -80 degrees C. They are suitable for use in the quality control of alpha-tocopherol. On the other hand, in some samples, we observed great variability in the rate of alpha-tocopherol degradation. However, there was lesser degradation when these plasma samples were stored at -80 degrees C instead of -20 degrees C. We therefore do not advise storing serum or plasma for more than 1 month at -20 degrees C for more than 3 months at -80 degrees C. This latter temperature is recommended in epidemiological studies.

Skin disorders and vitamin A metabolism disturbances in chronic dialysis patients: the role of zinc, retinol-binding protein, retinol and retinoic acid.

The authors have studied--in the plasma--the changes of zinc, retinol binding protein (RBP), retinol and retinoic acid with reference to the dermatological status of fifty chronically haemodialysed renal insufficiency patients divided into four subgroups (normal skin, dry skin, dry skin with keratosis, and only keratosis). The results of these groups were compared to those of thirty healthy subjects. The values of these variables do not show any significant difference in function of the dermatological subgroups; but, despite the considerable rise in the retinol binding protein and retinol levels in comparison with the controls (haemodialysis patients: RBP = 11.77 +/- 2.83 mumol X l(-1), retinol = 7 +/- 2.57 mumol X l(-1); controls; RBP = 2.76 +/- 0.62 mumol X l(-1), retinol = 2.16 +/- 0.53 mumol X l(-1] the electromicroscopic examination of skin biopsy samples from some of the patients did not reveal any sign of hypervitaminosis A in the lesions.

[Biological criteria of denutrition. Search of significant parameters for diagnosis and management in surgical departments]. / Critères biologiques de la dénutrition. Recherche de paramètres significatifs pour le diagnostic et la thérapeutique en milieu chirurgical.

Assessment of the nutritional status of surgical patients with a mean weight loss of 11.5 kg included determination of the following biochemical parameters: prealbumin, retinol-binding protein (RBP), serum vitamin A and serum zinc. Patients' immunological status was investigated by delayed hypersensitivity skin tests. Prealbumin and RBP are decreased in patients. RBP levels are significantly lower than in controls: RBP therefore seems to be a better criterion of denutrition than prealbumin. Serum RBP and vitamin A concentrations are not always correlated in patients; for instance, in malabsorptions, the sharp fall in serum vitamin A is isolated. The decrease in mean serum zinc concentrations is minor. Three patients have positive skin tests with severe biochemical disturbances; only serum zinc concentrations are normal and correlated with the results of skin tests. Interpretation of investigations in surgical patients is dependent on the cause of weight loss. However, biochemical and immunological assessment of the nutritional status can demonstrate specific deficits and improve preoperative nutrition.

[The PABA test in chronic pancreatitis: value of plasma para-amino benzoic acid determinations (author's transl)]. / Le test à l'acide para-amino-benzoïque dans les pancréatites chroniques. Intérêt des dosages sanguins.

Plasma concentrations and urinary excretion of para-aminobenzoic acid (PABA) were measured over a 6-hour period after administration of N-benzoil L-tyrosyl aminobenzoic acid (NBT-PABA) to 15 patients with chronic pancreatitis and 15 controls. The sum of plasma PABA concentrations at 1 hour and 2 hours was calculated for each subject. The resulting value proved to have a specificity of 100% and a sensitivity of 80%, as opposed to 86% and 67% respectively for urinary concentrations.

[Prevention of ocular toxicity of ethambutol: study of zincaemia and chromatic analysis (author's transl)]. / Prévention de la toxicité oculaire de l'éthambutol: intérêt de la zincémie et de l'analyse du sens chromatique.

In order to define the means of prevention of the ocular toxicity of ethambutol (EMB), 72 patients under treatment with EMB-INH-Rifampicin combination were subjected to systematic analysis of plasma, blood and urinary zinc levels together with a full ophthalmic examination. Comparison of the results from 12 patients sustaining ocular damage at the time of treatment with the results of 60 others: 1) demonstrates the existence of a correlation between plasma zinc levels before treatment and the probability of ocular damage from EMB (high risk for zinc is less than 0.70 mg/l - almost no risk for zinc greater than 1 mg/l); 2) confirms that dyschromatopsia is one of the first signs of ocular damage through EMB and thus constitutes an alarm signal; 3) suggests that the ocular toxicity of EMB might appear in the retina before the optic nerve.