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Biomedical subjects

R Sapin

Publications and source records attributed to R Sapin.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Regulation of endothelin-1 at rest and during a short steady-state exercise in 21 COPD patients.

Endothelin-1 (ET-1) is a vasoconstrictive peptide which may play a relevant role in the pathogenesis of pulmonary hypertension (PH) in COPD patients. We assessed the correlations of plasmatic ET-1 levels with pulmonary function data, arterial blood gases and pulmonary haemodynamics in 21 COPD patients with moderate to severe airway obstruction (FEV1: 1.19+/-0.49 l, mean+/-SD). There were 11 hypoxemic patients (PaO2 <65 mmHg). Six patients had resting PH (mean pulmonary artery pressure >/=20 mmHg). Eight patients had exercising PH (PAP >/=30 mmHg) during a short (6 min) 30 W steady state exercise. At rest, arterial ET-1 levels were significantly higher in COPD patients with hypoxemia when compared to those without hypoxemia (16.6+/-2.7 vs. 12.5+/-3.9 pM/l, P=0.02) and in COPD patients with PH when compared to those without PH (16.5+/-3.4 vs. 13+/-3.9 pM/l, P=0.04). Resting arterial ET-1 levels were negatively correlated with PaO2 (r=-0.45, P=0.05). At rest, the differences between mixed venous and arterial ET-1 levels were positively correlated with FEV1 (r=0.54, P=0.024). At exercise, the mean arterial ET-1 level was not significantly different from the mean resting ET-1 level (13.8+/-3.4 vs. 13.3+/-4 p M/l, NS). There were eight COPD patients who had decreasing arterial ET-1 levels between rest and the end of a 6 min exercise, and six COPD patients who had increasing arterial ET-1 levels. These variations of arterial systemic ET-1 levels from rest to exercise were negatively correlated with FEV1 (r=-0.66, P=0.01). We conclude that in COPD patients (1) at rest, arterial ET-1 levels are increased in hypoxemia or pulmonary hypertension and (2) at rest or during exercise, the turn-over of ET-1 may be dependent of the degree of the bronchial obstruction.

Aged↗
PubMedDate not supplied

[Treatment and monitoring of primary hypothyroidism].

Treatment of primary hypothyroidism requires a long-term hormonal therapy with levothyroxine which restores a normal TSH value. In a series of 192 patients followed up for at least 3 years we tried to evaluate the variability of maintenance dosage and to analyse the factors predictive of replacement dosage. The L-T4 dosage varied from one individual to the other, from 0.6 to 3.2 micrograms/kg. The mean maintenance dosage (118 +/- 38 micrograms/day) was similar in men and women weight for weight, but it was higher in subjects aged under 60 and in those with Hashimoto's or congenital hypothyroidism. There is a positive linear relation between the equilibrium dose and the TSH value (n = 0.84; p < 0.001) and a negative relation with the L-T4 concentration (n = 0.71; p < 0.001). The yearly variation of dosage in each individual was small (about 3.5%) and of the same order as the variation of weight. We conclude that the L-T4 maintenance dosage depends on the cause of hypothyroidism, on the importance of biochemical abnormalities and on the patient's age, sex and weight. In practice, however, the necessary dosage is difficult to predict. In the equilibrium phase the need for replacements is remarkably stable. A yearly assay of baseline TSH seems to be sufficient to evaluate the quality of hormonal compensation in the absence of intercurrent events.

Adolescent↗
PubMedDate not supplied

[Two-center evaluation of eight kits for antithyroid peroxidase autoantibodies determinations].

We compared eight antithyroid peroxidase antibody assay kits in two centres, by use of panel sera from 269 patients: controls (n = 100), patients with autoimmune thyroid diseases (n = 77 Graves' disease, Hashimoto's thyroiditis), with non autoimmune thyroid diseases (n = 69 nodular goiter, differentiated thyroid carcinoma), and with autoimmune disease without thyroid pathology (n = 23 diabetic subjects, rheumatoid polyarthritis). On the controls sera we observed different distributions of values. The cut-off values of each kit was, in most cases, similar to the value noted in the manufacturer's instructions. In the clinical study, we observed few differences. The majority of assays demonstrated high diagnostic performance. Some false positive results and the non assessment of some sera by competitive immunoassay were observed.

Adolescent↗
PubMedDate not supplied

[Macroprolactin detection: a new approach].

Macroprolactin is a complex of prolactin with immunoglobulins (IgG) that has limited or no biological activity in vivo. Immunoassays for prolactin have variable reactivity with macroprolactin. Therefore the presence of macroprolactin should be considered in the differential diagnosis of hyperprolactinemia. We compared a valid screening test for macroprolactin, polyethyleneglycol (PEG) precipitation, with the determination of the ratio of the results of two prolactin assays: Elecsys with high cross-reactivity with macroprolactin and Centaur with low cross-reactivity. In 59 negative samples subjected to the PEG test (precipitation < 50%), the Elecsys/Centaur ratio ranged between 1.11 and 1.45. Among 35 positive samples (precipitation > 60%), 33 had, as expected, an increased ratio (over 1.45), 1 a normal ratio and 1 a decreased ratio (1.07). This decreased ratio could be due to a particular form of macroprolactin poorly recognised by the Elecsys assay. Among 5 samples in the grey zone (precipitation between 50 and 60%), the ratio was increased in 2, normal in 1 and decreased in 2. Apart from one false negative case (normal ratio with positive PEG test), the results of the Elecsys/Centaur ratio method were in good agreement with those of the PEG test. The ratio method could be helpful for samples with PEG test results in the grey zone, before undertaking a complete analysis of circulating molecular forms by gel filtration chromatography. Out of the 5 five samples in the grey zone, the ratio was 4 times out of the reference range: 2 increased, 2 decreased. Our results also underline the necessity of reevaluating the Centaur prolactin reference range from samples without macroprolactin.

Adolescent↗
PubMedDate not supplied

[Thyroxine (T4) and tri-iodothyronine (T3) determinations: techniques and value in the assessment of thyroid function].

Hormonal production of the thyroid gland is constituted of thyroxine or T4 (80%) and triiodothyronine or T3 (20%). In the circulation, whole T4 originates from thyroid secretion but most of T3 (80%) is produced extrathyroidally from T4 deiodination. Conversion of T4 to T3 may be influenced by various conditions and circulating T3 is a less reliable reflection of thyroid hormone production than T4. In serum most of T4 and T3 is bound to binding proteins and only 0.02% of T4 and 0.3% of T3 is free. Because of their higher diagnostic performance, free T4 (FT4) and free T3 (FT3) measurements have superseded total (free + bound) hormone determination. Total hormone measurements remain useful for research studies or in case of severe hyperthyroidism. Equilibrium dialysis/RIA is considered as the reference method for free hormone measurements. Routine clinical laboratories use automated direct two-step or one-step immunoassays with a high molecular weight ligand or labelled antibody. Free hormone measurement remains technically demanding, especially in sera from severe non-thyroid ill patients with low serum thyroxine binding capacity. Interference from anti-thyroid hormone antibodies and familial dysalbuminemic hyperthyroxinemia depends on the assay method, but is now less marked and less frequently detected. To be able to correctly interpret the results of an assay, it is necessary to assess its performance in biologically and clinically well-characterised serum samples. FT4, and FT3 measurements, if FT4 is normal and hyperthyroidism suspected, are used to confirm and assess the level of hypo and hyperthyroidism (overt or subclinical). When the thyroidal status is unstable (first months of a thyroid treatment, altered L-T4 dose, subacute thyroiditis) or when the hypothalamic-pituitary function is disturbed (central hypothyroidism), TSH determination is diagnostically misleading and only free hormone measurements are reliable for thyroid function assessment.

Humans↗
PubMedDate not supplied

Changes in serum testosterone levels after myocardial infarction.

To evaluate the effect of a severe non-endocrine disease on testosterone levels we determined the total testosterone (T), free testosterone (fT), myoglobin and myosin plasmatic levels in 18 men at the time of hospitalization for acute myocardial infarction (AMI), and 1, 3, 7 and 21 days later. Five different methods for determining fT were applied and compared; 1) radioimmunoassay after ultrafiltration, 2) direct analogue based radioimmunoassay (RIA), 3) calculation from total T, sex-hormone-binding globulin (SHBG) and albumin concentrations, 4) calculation from total T, SHBG concentrations with albuminemia fixed at 40 g/L, and 5) evaluation by the (total T)/(SHBG) ratio (fT index). After AMI the total T and fT decreased rapidly (minimum at day 1) and then increased until day 21. While a lower sensitivity in detecting small changes was noted for the direct analogue based fT RIA and for the calculation using a fixed albuminemia, the evolving pattern of the 5 different fT determinations was similar despite different absolute values. However, there was a wide scattering in the results from the different methods used to determine fT. Compared to ultrafiltration, the fT values were lower by direct analogue based assay and higher by calculation. There was a trend of correlation between changes in total T and the maximum myosin concentration (r = 0.557, p = 0.02), showing a relationship between the hormonal changes and the severity of the myocardial infarction.

Adult↗
PubMedDate not supplied

[Proposed reference values for nine methods for measurement of free thyroxin].

In connection with a comparative study of nine kits for the measurement of free thyroxin, we determined reference values in a adult control group of 81 women and 73 men. The correlations observed between the kits are associated with very large differences in the results obtained. The reference ranges are more or less broad according to the kits, but narrower than those offered by the manufacturers.

Adolescent↗
PubMedDate not supplied

[Ultrasensitive determination of thyrotropin. Improvement in the performance and reduction of the cost of thyroid function tests].

The characteristics of an ultrasensitive thyrotropin (TSH) assay method using monoclonal antibodies (TSH-U) were determined in euthyroid subjects, either healthy or with extra-thyroid disease, in treated and untreated hyper-and hypothyroid subjects and in subjects under amiodarone. The thyroid function was evaluated by free thyroxine (FT4) and free triiodothyronine (FT3) assays and by TSH tests and TSH response to TRH. With a sensitivity of 1 and a specificity of 0.94, the TSH-U assay proved highly reliable to evaluate the thyroid function. Dysthyroidism can be excluded when TSH-U levels are normal (0.15 to 4.5 microU/ml). In case of low TSH-U level, measurements of FT4 and FT3 and, if required, thyroid gland scintigraphy are necessary to confirm a diagnosis of hyperthyroidism. In contrast, a high TSH-U level is sufficient for affirm diagnosis of hypothyroidism. The TSH-U assay makes the TRH test redundant and can differentiate between hyperthyroxinaemia with euthyroidism and with hyperthyroidism. It is an effective method to detect disorders in thyroid function and it calls for a re-evaluation of thyroid diagnostic strategy.

Adult↗
PubMedDate not supplied

[Idiopathic exudative gastroenteropathy with apparently spontaneous recovery : a case report (author's transl)].

The sudden occurrence of oedemas of inferior limbs in a 36 years old woman, has been ascribed to a severe hypoalbuminemia consecutive to an exudative gastroenteropathy of which etiology remained unknown. A successful and lasting evolution followed the correction of hypoalbuminemia by albumin perfusions in exclusion of any other therapy. Such observations though frequent in the childhood are exceptional at maturity.

Adult↗