[Comparison of different methods for serum folate assay]. / Comparaison de différentes méthodes de dosage des folates sériques.

Folates were determined in 148 patient sera, using four different methods: a microbiological assay (Reference Method), two radioassays (Magic B12 FOL [NB] and SimulTRAC SNB no boil kits) and a non isotopic competition method (Magic Lite kit). Folate mean varied according to the methods 10.0 nmol.l-1 (reference method), 12.2 nmol.l-1 (Magic Lite), 8.7 nmol.l-1 (Magic B12 FOL [NB]) and 10.8 nmol.l-1 (SimulTRAC SNB NO boil). Poor correlations were also noted (0.83 < r < 0.95, figures 1 and 2). Differences between methods were explained according to the literature.

Pharmacokinetics of vitamin K1 in low-birth-weight neonates.

The pharmacokinetics of vitamin K1 was studied in 21 newborn infants. 11 neonates had received no parenteral loading dose prior to the study (group I), while 10 had been injected 5-10 mg vitamin K1 at birth (group II). At postnatal age 2-9 h, 1 mg of vitamin K1 was injected intravenously, and small samples of blood (less than or equal to 500 microliter) were collected at different times during 6 h. Serum vitamin K1 and its epoxide were assayed by high-performance liquid chromatography (HPLC). In both groups, the disappearance curve showed two exponential components: a fast distribution component during the 1st h and a slower elimination component during the next 5 h. In group I, the plasma half-life of the first component was between 18 and 52 min (median 23 min), and the half-life of the second was between 67 and 179 min (median 109 min). Both half-lives were significantly higher in group II. The volumes of distribution were suggestive of distribution into plasma during the first phase and roughly into the extracellular water for the second component. Epoxide was detected in most patients 15 min after vitamin K1 injection, and after 3 h its concentration was higher than the concentration of vitamin K1. These data suggest that the kinetics of vitamin K1 in neonates is not very different from that in adults. The newborn infant is able to oxidize vitamin K1, a phenomenon in keeping with the gamma carboxylation of glutamic acid.

[Effects of a rise in ambient temperature on the metabolism of vitamin A in the rat during growth. Studied by measurements in the liver and plasma]. / Effets d'une élévation de la température ambiante sur le métabolisme de la vitamine A chez le rat en cours de croissance. Etude au moyen de mesures dans le foie et le plasma.

In growing rats, an increase in ambient temperature from 25 to 34 degrees C decreased the level of vitamin A by 54% in plasma and 17% in the liver. But the quantity of vitamin A available for the organism (quantity per gram body weight) remained unchanged. Various hypotheses have been formulated with a view to further research.

Comparison of three commercial kits and a microbiological assay for the determination of vitamin B12 in serum.

Different methods are available for cobalamin determination in serum. Microbiological and radio ligand binding assays are the most commonly used. Kits involving non-isotopic competitive-binding assay have been recently commercialized. In the present work, cobalamins were determined in 146 patient sera, using four methods: a microbiological method, two no boil radio ligand binding assay kits (Magic B12 FOL (NB) from Ciba-Corning and SimulTRAC SNB No Boil from Becton Dickinson) and a non-isotopic kit with acridinium ester labelled cobalamin (Magic Lite from Ciba-Corning). Median (range) cobalamin concentrations in pmol l-1 were 317 (15-1291) using the microbiological method, 355 (25-3469) using the Magic Lite kit, 355 (35-2312) using the Magic B12 FOL (NB) kit and 380 (37-2021) using the SimulTRAC SNB No Boil kit. The ANOVA test indicated that differences between methods were statistically significant (p < 0.01). Competitive-binding methods gave higher results than the microbiological method. Although correlation coefficients were not excellent (0.88 < r < 0.96), the results obtained with the different methods were generally similar and confirmed that competitive methods are useful for detecting low serum concentration of vitamin B12.

"ESVITAF". Survey on the vitamin status of the French: relationships between nutrient intake and biochemical indicators.

The relationships between dietary data and biochemical nutritional status for vitamins B1, B2, A, E, beta-carotene, folic acid and iron have been studied using data from a survey conducted on 710 adults. Significant correlations were found between riboflavin intake and biochemical values for males only (r = -0.105, p less than or equal to 0.05), between beta-carotene intake and plasma beta-carotene (r = 0.232, for males and r = 0.292 for females, p less than or equal to 0.001), and between iron intake and plasma iron for males only (r = 0.115, p less than or equal to 0.05). Concerning nutrient densities, correlations were significant between dietary riboflavin and biochemical measure (r = 0.163, p less than or equal to 0.01 for males, r = -0.135, p less than or equal to 0.05 for females), between vitamin A intake (expressed in retinol equivalent) and beta-carotene (r = 0.212, p less than or equal to 0.001 for males, r = 0.157, p less than or equal to 0.01 for females) and for males only, between dietary iron and hemoglobin (r = 0.144, p less than or equal to 0.01). The dietary data for each nutrient were examined for their sensitivity, specificity and predictive values in identifying subjects with substandard or overstandard biochemical values. For all nutrients the positive predictive value percentage was always below 25%, the negative predictive value percentage always under 75%.

[Imerslund-Najman-Grasbeck anemia. Apropos of a case]. / L'anémie d'Imerslund-Najman-Grasbeck. A propos d'un cas.

Imerslund-Najman-Grasbeck disease is a rare inherited megaloblastic anaemia secondary to a selective malabsorption of vitamin B12 by ileal enterocytes. The authors report on a 4 year-old tunisian girl who presented as visceral infantile leishmaniasis because of huge splenomegaly and major anaemia. The diagnosis of Imerslund disease was performed on the basis of the association of typical megaloblastic cells in the marrow, permanent proteinuria and favourable outcome under parenteral B12 administration. In addition, ther were no folate deficiency, no anti-intrinsic factor antibodies and no intrinsic factor deficiency. The outcome of the disease is always favourable if parenteral administration of vitamin B12 maintained.

Reference intervals for vitamins B1, B2, E, D, retinol, beta-carotene, and folate in blood: usefulness of dietary selection criteria.

Reference intervals for normal concentrations in blood of vitamins B1, B2, E, D, retinol, beta-carotene, and folic acid were determined from a selected sample of people attending a Health Examination Center or being examined in occupational health services in France. This reference sample consisted of 362 men and women, ages 18 to 44 years, selected according to the main variation factors known for the vitamins studied: consumption of tobacco and alcohol, ponderal index (relating height and weight), use of drugs and oral contraceptives, and past history of surgical or medical treatment. Reference intervals were determined for each sex. Vitamin B1 (erythrocyte transketolase activity), plasma retinol, and folic acid values in whole blood are significantly higher in men than in women (p less than 0.001), but vitamin B2 (activation of erythrocyte glutathione reductase) and plasma beta-carotene values are significantly higher in women (p less than 0.001 and less than 0.01 respectively). Dietary intake of vitamins produced no significant displacement of the reference values. For each vitamin we discuss the other major sources of variation factors and the usual values reported in the literature.

Biotin dependent multiple carboxylase deficiency presenting as a congenital lactic acidosis.

Two patients presented in early childhood with (i) alopecia, skin rashs, and dermatitis, (ii) severe hypotonia, ataxia and motor retardation, (iii) frequent episodes of ketoacidosis with hyperlactacidemia. Propionic and methylcrotonic aciduria only appeared on high protein diet. Mitochondrial biotin-dependent carboxylase activities were decreased in the liver and leukocytes, but were similar to control values in fibroblasts cultured in a biotin-free medium. In addition, the plasma biotin was found to be significantly lower than in control subjects. These disorders responded to biotin administration, pointing to biotin-dependent multiple carboxylase deficiencies (MCD). Our report stresses the polymorphism of MCD and suggests that MCD could be of two types: impaired vitamin metabolism (absorption, plasma transport), might result in low plasma biotin with generalized MCD involving acetyl CoA carboxylase. Defective mitochondrial holocarboxylase synthetase might lead to a pure mitochondrial MCD, with fibroblastic deficiency and presumably normal biotin metabolism.