[Vitamin D and multiple sclerosis. A prospective survey of patients of Poitou-Charentes area]. / Vitamine D et sclérose en plaques. Étude prospective d'une cohorte de patients de la région Poitou-Charentes.

INTRODUCTION: Recent reports demonstrate the implication of vitamin D in multiple sclerosis (MS). METHODS: In a multicentric regional study (Poitou-Charentes area) during the first trimester 2010, we measured the 25-OH vitamin D serum level in 170 consecutive MS patients, and in 170 controls matched for age (±4 years), sex and date of blood sample analysis. We searched for correlations between 25-OH vitamin D serum levels and the MS form, the disability (EDSS), the relapse rate during the previous year and the presence and number of enhancing lesions on T1-weighted MRI dating less than 12 months in relapsing MS. RESULTS: Hypovitaminosis D was very frequent in MS patients and 25-OH vitamin D serum level was significantly lower (14.5 ± 9.2 mcg/mL) in MS patients than in the control group (16.7 ± 9.6 mcg/mL). This serum level was inversely correlated with the degree of disability measured with EDSS score and was lower in secondary progressive (RR-SP) and primary progressive (PP) MS than in relapsing MS (RR). No correlation was found between 25-OH vit D serum level and relapse rate during the previous year in RR MS and the presence and number of enhancing lesions on T1-weighted MRI dating from less than 12 months. CONCLUSION: 25-OH vit D serum level is very low in MS, mainly in RR-SP and PP MS and is correlated with disability. This suggests MS patients should be screened for vitamin D deficiency and given supplementation systematically when hypovitaminosis D is discovered.

Evaluation of the Abbott IMx ultrasensitive II hTSH immunometric assay in three European centres: a comparison with established commercial immunometric assays for thyrotropin.

The Abbott Ultrasensitive II hTSH assay was evaluated in three European centres and its performance compared with its predecessor and with commercially available kits. A total of 408 individuals was included in the study (140 euthyroid, 116 hyperthyroid and 86 hypothyroid subjects, as well as 26 patients with non-thyroidal illness and 30 patients with thyroid cancer). The kit was evaluated for (im)precision and analytical and functional sensitivity according to ECCLS-Guidelines. The analytical sensitivity lay between 0.004 and 0.013 mU/1, the mean value being 0.008 mU/1, results being from 12 runs. The functional sensitivity gave a coefficient of variation below 20% at a concentration of 0.05 mU/1 under routine conditions. Inter-assay precision was less than 7% at 0.25 mU/l (range 5.3-6.8%), less than 6% at 6 mU/l (range 4.0-5.2%) and less than 9% at 30 mU/l (range 6.5 - 8.7%). Intra-assay (im)precision was not calculated as the Abbott IMx is designed to run on singlicate determinations.

Multicentre evaluation of a two-step automated enzyme immunoassay of free thyroxine.

The two-step enzymatic immunoassay of free thyroxine (IMx FT4, Abbott Laboratories, Chicago, IL) was studied in three centres. The assay involved a fluorimetric measurement and took 45 minutes using a completely automated procedure. The results were compared with those from the free thyroxine two-step radioimmunoassay and with the "calculation" of free thyroxine. The analytical precision was found to be excellent if the analyser was correctly set. The IMx FT4 assay seemed unaffected by increased concentrations of albumin and of non-esterified fatty acids (oleic acid) up to 5 mmol/l. The euthyroid reference interval, defined as that including 95% of 194 control subjects, was 12-21 pmol/l. A limited overlap existed between euthyroid and hyperthyroid patients, but a larger one was seen between the euthyroid and hypothyroid population, the latter including subclinical hypothyroidism. IMx FT4 results agreed well when compared with those from two-step radioimmunoassays. The IMx FT4 technique gave rise to a low percentage of elevated results in patients being treated with heparin, but was undisturbed by autoantibodies to thyroxine and triiodothyronine which were present in one hypothyroid patient.

Comparative measurement of progesterone receptors in breast cancer by biochemical and immunoenzymatic assays.

The measurement of progesterone receptors (PR) by enzyme immunoassay (Abbott Laboratories, EIA monoclonal) and biochemical assay using a tritiated ligand (promegestone, R5020) was studied and compared by using the statistical method of Passing and Bablok. In order to improve the reliability of the biochemical method, data were analysed using a hyperbolic model which avoids the need to determine non-specific binding experimentally. The comparison of hyperbolic (Y) and Scatchard (X) plots gave a regression curve of Y = 0.93 x + 1.34 fmol/mg of protein. Cytosols from 70 human breast cancers homogenized in the absence of KCl were assayed for PR by both the EIA (Y) and biochemical (X) methods. The linear regression obtained gave Y = 1.21 X + 1.97 fmol/mg of protein. In the presence of 0.4 M KCl-Tris buffer, the corresponding result for 80 human breast cancers was Y = 3.11 X + 1.91 fmol/mg of protein. The slopes of the two regression lines obtained in the presence or absence of KCl were significantly different. Results of the biochemical and EIA methods were similar in the absence of KCl, whereas EIA gave higher values when KCl was used. This discrepancy probably stem from the methodological differences between the two methods: the biochemical assay measures active steroid binding sites while EIA measures antigenic activity. The authors conclude that clinical studies are required before using high-salt extraction buffer in routine PR determination by the EIA method; this will result in improvements in the determination of the hormone dependence and/or the prognosis of human breast cancers.

Four nonisotopic immunoassays of free thyroxin evaluated.

We evaluated four new nonisotopic immunoassays of free thyroxin (FT4)--Amerlite FT4 (Amersham International), Magic Lite FT4 (Ciba Corning Diagnostics), Stratus FT4 (Dade--Baxter Travenol), and FT4 Enzelsa (Compagnie ORIS Industrie)--by comparison with two FT4 radioimmunoassays: Amerlex and Sclavo. Inter- and intra-assay coefficients of variation were less than 10% in the working range and there was no significant interaction between the tracer conjugate and albumin. All methods except Enzelsa gave results equivalent to those obtained with the Sclavo chromatographic technique. In a population consisting of 325 euthyroid subjects and 111 hyperthyroid and 61 hypothyroid patients without any treatment, we observed slight overlaps between the hyperthyroid and euthyroid populations and diagnostic sensitivities were approximately 0.95 and 0.80 for hyperthyroidism and hypothyroidism. In specific populations (69 patients with chronic renal failure, 20 patients in intensive-care, 17 patients treated with heparin, and 27 pregnant women), results were quantitatively similar to those obtained by the Sclavo assay. We conclude that these nonisotopic methods are a valid alternative to current radioisotopic commercial methods.

[Evolution of salivary estradiol levels during the spontaneous menstrual cycle. Correlation between saliva and plasma]. / Evolution des taux d'estradiol salivaire au cours du cycle menstruel spontané. Corrélation salive-plasma.

The measurement of steroid concentrations is recommended in the exploration of the different endocrine functions. The salivary concentrations are the reflect of the free biologically active fraction in the plasma. In this study we have used a sensitive and specific method that can be routinely applied in salivary extradiol (SE2) RIA, using a 3 CMO 125I histamine derivative as a tracer. This study related to 12 normal spontaneous menstrual cycles and two abnormal spontaneous cycles. Saliva samples were collected daily throughout the menstrual cycle. Plasma samples were collected simultaneously to compare the salivary and plasma patterns. In the follicular phase SE2 was low: M +/- SD = 9.4 +/- 2.4 pmol/l. During the periovulatory period, the mean level of SE2 the day of the preovulatory peak was 27.6 +/- 8.6 pmol/l. In the luteal phase the SE2 levels fluctuated in a serrated manner with a mean of 11.7 +/- 3.4 pmol/l. The difference between the different phases is significant at the probability threshold 0.01. We have compared the salivary and plasma patterns during the different phases. At the beginning the salivary/plasma ratio was 3.4 +/- 0.9%. During the periovulatory period this ratio was only 2.5 +/- 0.6% and the end of the cycle 2.8 +/- 1%. The statistic study showed that these differences were significant at the probability threshold 0.01.

One-step chemiluminescent immunoassay of free thyroxin with acridinium-ester-labeled thyroxin evaluated and compared with a two-step radioimmunoassay.

This new one-step chemiluminescent immunoassay of free thyroxin (FT4) involving a thyroxin-immunoglobulin conjugate labeled with acridinium ester (Magic Lite System; Ciba Corning Diagnostics Corp., Medfield, MA) is rapid (one 1-h incubation), requires two calibrators per run, and takes 10 s per sample for the quantification step. Analytical performances were excellent: within- and between-run CVs of less than 10% in the working range, no significant effect of hemolysis, bilirubin, or lipemia, and no significant interaction between the conjugate and the thyroxin-binding proteins. Magic Lite results (y) correlated well with those obtained by the Sclavo (x) two-step radioimmunoassay (Sclavo, Siena, Italy): y = 1.35x + 1.32 (r = 0.94, n = 267, P less than 0.001, Sxy = 6.29). Clinical sensitivities (diagnostic efficiencies) for hypothyroidism and hyperthyroidism were 0.91 and 0.98 for normal interval limits of 12 and 21.5 pmol/L (95% confidence interval). Magic Lite results in situations where patient therapy, treatment, or unusual conditions can result in a lack of correlation between the clinical status and the FT4 values were qualitatively the same as those obtained by the Sclavo assay.

Breast cancer estrogen receptor assays: assessment of a direct hyperbolic fitting to analyse multipoint binding data.

Analysis of breast cancer estrogen receptor multipoint binding assay is performed by fitting experimental data to a hyperbolic model derived from the law of mass action. The calculations performed on a microcomputer are carried out from the total bound and free ligand concentrations. The parameters estimated by hyperbolic fitting, receptor concentration N and constant of dissociation K, well agree with those obtained by Scatchard's transformation. N and K derived from hyperbolic analysis are much less susceptible to the influence of experimental errors. The method is more reliable at low receptor concentrations. The main advantage of the hyperbolic fitting is to simplify the technical methodology in clinical laboratory practice; there is no need to determine the non-specific bindings experimentally. Calculations can be easily automated on any laboratory microcomputer. Assays of any kind of receptor could be analysed by the hyperbolic fitting when the physical-chemical equilibrium between receptor, nonsaturable component and ligand can be approximated by a two-component model.

Chemiluminescence immunoassay of thyrotropin with acridinium-ester-labeled antibody evaluated and compared with two other immunoassays.

A new chemiluminometric immunoassay of thyrotropin (TSH) involves antibody labeled with acridinium ester ("Magic Lite System," Ciba Corning Diagnostic Corp.). The assay is rapid, with two incubations totaling 2.5 h, requires two standards per run, and takes 10 s per sample for the quantification step. Analytical performance, within- and between-run reproducibilities, and linearity were excellent. The detection limit is 0.04 milli-int. unit/L. Results correlated well with those obtained by immunoradiometric assay (RIA-gnost hTSH, Hoechst-Behring) and immunofluorometric assay (hTSH Delfia, LKB): r = 0.975. TSH measurements in 32 euthyroid subjects ranged from 0.4 to 4.8 milli-int. units/L (mean 1.35 milli-int. units/L). TSH values for 51 hypothyroid and subclinically hypothyroid patients ranged from 2 to 65 milli-int. units/L. TSH values for 33 hyperthyroid patients (less than 0.14 milli-int. unit/L, less than 0.04 milli-int. unit/L in 16 of the 33) were clearly lower than for most untreated euthyroid subjects. For 169 other individuals whose thyroid function was being routinely assessed. TSH ranged from 0.4 to 4.8 milli-int. units/L, three had TSH less than 0.14 milli-int. unit/L, and four had TSH between 0.14 and 0.4 milli-int. unit/L. This system is as efficient and reliable for screening for thyroid function as the two comparison systems.