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.

[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.

Effect of physiological concentrations of insulin and glucagon on the relationship between nonesterified fatty acids availability and ketone body production in humans.

To determine the effect of insulin and glucagon on the transformation of nonesterified fatty acids (NEFA) into ketone bodies (KB), we measured simultaneously in normal subjects NEFA and KB kinetics at different NEFA levels in the presence of basal (control test) or increasing insulin concentrations with glucagopenia (somatostatin + insulin infusion, insulin test) and without glucagopenia (somatostatin + insulin + glucagon infusion, glucagon test). NEFA levels were controlled during these tests by an intravenous (IV) infusion of a triglyceride emulsion. During the control test, a moderate increase of NEFA (464 +/- 30 to 715 +/- 56 mumol/L) increased the percentage of NEFA converted into KB (13.3% +/- 1.4% to 26.4% +/- 2.1%, P less than .05), and there was a linear relationship between this percentage and NEFA levels (r = .788, P less than .01). During the insulin and glucagon tests, the progressive increase in NEFA induced by the triglyceride emulsion infusion was associated, despite the increase of insulinemia, with an increase in KB production rate (P less than .05) and in the proportion of NEFA used for ketogenesis in the presence (8.1% +/- 1.2% to 14.2% +/- 6.3%, P less than .05) and absence (15.7% +/- 2.8% to 25.2% +/- 3.99%, P less than 0.05) of glucagopenia. In both tests, this percentage was always linearly related with NEFA levels (P less than .05) and the slopes of these relationships were comparable to that observed in the control test. However, the fraction of NEFA used for ketogenesis was always higher (P less than .05) during glucagon substitution than in its absence.(ABSTRACT TRUNCATED AT 250 WORDS)

[Vaccination against hepatitis B virus at the Lyon Pasteur Institute. A seven-year evaluation]. / Vaccination contre le virus de l'hépatite B à l'Institut Pasteur de Lyon. Bilan de sept ans.

Results of immunization against hepatitis B among Pasteur Institute staff members are reported. Prior to immunization, 439 subjects were tested for hepatitis B virus (HBV) markers, including HBs antigen, anti-HBs antibody, and anti-HBc antibody (Ausria, Ausab, Corab assays; Abbott). Forty-seven subjects tested positive for anti-HBs antibody. 317 subjects negative for all the HBs markers studied were given three intramuscular doses of Hevac B (Pasteur vaccins) at one-month intervals. Anti-HBs antibodies were assayed after the third injection with the following results: mean titer, 1,454 mIU/ml, standard deviation, 5,349 mIU/ml, and range, 4 to 41,100 mIU/ml. Anti-HBs titers above 10 mIU/ml were found in 879.4% of subjects. Non-responders and weak responders (anti-HBs titer under 10 mIU/ml) were given a fourth dose of vaccine. Ultimately, after the last (third of fourth) injection 97.6% of subjects had protective antibody titers. No case of HBV infection was seen during the seven-year follow-up period.

[Plasma fibronectin and collagen type IV in diabetic patients. Influence of therapy]. / Etude de la fibronectine et du collagène de type IV plasmatiques chez le diabétique. Influence de la thérapeutique.

Fibronectin (by laser nephelometry) and collagen IV blood levels (by radioimmunoassay) were studied in 183 diabetics and compared with 101 non diabetic patients. Diabetics have more collagen IV and less fibronectin than non diabetics. Divergence has increased since 20 years old; fibronectin blood levels is always low in diabetics, even in the young. Collagen IV is higher in diabetics with angiopathy, and specially if insulin dependent. Diabetics which have a good control have normals levels. In the other hand when HBA1C greater than or equal to 9%, collagen IV blood level increases quickly and fibronectin level decreases. The importance of the antidiabetic treatment is underlined.

[Assay of circulating anti-insulin antibodies by radioimmunoprecipitation]. / Dosage des anticorps anti-insuline circulants par radio-immunoprécipitation.

We report a radio-immunoprecipitation method for the measurement of circulating insulin antibodies using porcine, bovine or human radiolabeled insulin and precipitation of the bound fraction by a combined polyethylene glycol--second antibody method. The coefficient of variation for intra- and inter-assay is below 8,5 p. cent and 17 p. cent respectively. 100 insulin treated patients sera were tested in the three systems: the results showed a great scattering; for the same serum, the values obtained with porcine and human insulins are below that with bovine insulin. The data correlated statistically significantly with those found with a commercial kit (r = 0,97, n = 170, t = -4,91, p greater than 0,001).

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.