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Biomedical subjects

R Sapin

Publications and source records attributed to R Sapin.

At least 37 records · Page 2Linked to original sources
PubMed1997

Two centre evaluation of seven thyrotropin kits using luminescent detection.

We compared seven thyrotropin luminescent immunometric assay kits in two centres, by use of panel sera from 438 patients: controls (n = 203) and different groups of subjects: hyperthyroidism (n = 42), hypothyroidism (n = 46), non-thyroidal illness (n = 102), geriatrics (n = 24) and selected patients previously treated for thyroid cancer and maintained on suppressive doses of L-thyroxine (n = 17), anti-thyrotropin antibody (n = 4). We did not observe any significant differences in analytical tests among the seven methods on the Probioqual control sera, Anemia control serum and human serum pools. The linearity of serial dilutions was found with all kits. Some variations were noticed at extreme dilutions. The within-assay precision was acceptable in all cases. The functional sensitivity limits were estimated from 20% compound precision profile: they ranged from 0.011 to 0.030 mU/l. In the clinical study, the seven assay demonstrated high diagnostic performance. Some interference by heterophilic antibodies were observed.

Aged↗
PubMed1996

[Thyroid function and dysfunction in the elderly].

The consequences of aging function are appreciated in various ways. In fact most of the thyroid hormone abnormalities described in the elderly are secondary to associated disease or treatments. Health and nutritional status seem to be more determinant than age. However, there is an increased prevalence of dysthyroidism in the elderly. Symptoms may be misleading and induce severe general repercussions. Mild or occult forms of dysthyroidism characterized by abnormal TSH levels with normal free thyroid hormone levels are not uncommon. Their clinical significance and their prognosis without treatment are still unresolved. The frequency of dystrhyroidism during old age and the possibility of a specific treatment may be in favour of a screening by a systematic TSH determination in elderly patients.

Aged↗
PubMed1996

Familial dysalbuminemic hyperthyroxinemia and thyroid hormone autoantibodies: interference in current free thyroid hormone assays.

The interference of familial dysalbuminemic hyperthyroxinemia (FDH), antithyroxine (anti-T4) or antitriiodothyronine (anti-T3) antibodies in serum free T4 (FT4) or free T3 (FT3) assays depends on the assay method: two-step immunoextraction, one-step labelled ligand (analogue or derivative tracer) or labelled antibody (solid-phase antigen-linked technique: SPALT) method. For FDH subjects, only FT4 measurements by one two-step method gave reliable results in all cases. However, the overestimation was less marked with new SPALT assays than with previous analogue-based assays. In sera containing anti-T4 antibodies, two-step assays and SPALT assays with a T3-coated solid phase can be considered as reliable for FT4 determination. All other methods including SPALT assays with a T4-coated solid phase may give falsely high results. In sera containing anti-T3 antibodies, SPALT FT4 and FT3 assays with a T3-coated solid phase may give spuriously high values. Anti-T3 antibodies do not interfere in two-step FT3 assays and SPALT FT3 assays with a T2-coated solid phase, but may give high FT3 values as measured by analogue or derivative methods. Moreover, SPALT free thyroid hormone assays may also be subject to interference from antibodies directed towards the assay solid phase.

Autoantibodies↗
PubMed1996

Highly sensitive immunoradiometric assay for serum thyroglobulin with minimal interference from autoantibodies.

Five monoclonal antibodies (MAbs) directed against antigenic domains on thyroglobulin (Tg) not recognized by most anti-Tg human autoantibodies (aAbs) have been used to develop an improved IRMA for serum Tg with a limit of detection of 0.2 micrograms/L. Samples are incubated for 3 h in tubes coated with four anti-Tg MAbs. After washing, the tubes are incubated with the tracer MAb for 20 h at room temperature. Dilution and reproducibility tests demonstrated assay reliability. Tests performed on samples with (n = 361) or without (n = 283) aAbs showed that the TG IRMA Pasteur is largely independent of the marked interference generally caused by aAbs. These results were confirmed with an extended population of 2759 samples. For a cutoff of 1 micrograms/L, sensitivity and specificity were 0.97 and 1, respectively, in a follow-up of differentiated thyroid carcinoma in patients treated by total thyroidectomy.

Animals↗
PubMed1995

Immunogenicity of intraperitoneal insulin infusion using programmable implantable devices.

Intraperitoneal insulin infusion using implantable devices in insulin-dependent diabetic (IDDM) patients is promising since it improves diabetic control and decreases frequency of hypoglycaemia. However, preliminary data show a striking increase in plasma levels of anti-insulin antibodies with this therapy. In order to more precisely evaluate the immunogenicity and its consequences, anti-insulin antibody levels in 62 IDDM patients were assessed every 3 months during a 2-year period following pump implantation. At the same time, diabetes control was evaluated with HbA1c, mean blood glucose levels, standard deviation of the daily blood glucose levels and the frequency of low blood glucose (< 3.58 mmol/l). Factors involved in antibody formation such as age, gender, HLA typing, and complement C4 alleles were also studied. After implantation, anti-insulin antibody levels increased significantly from 3.14% (range 0-26%) to 8.34% (0-49%) after 1 year and remained elevated. Patients were divided into two groups: responders able to show at least one antiinsulin antibody titre higher than 15% and non-responders whose titres were always lower than 6%. None of the factors studied was shown to statistically influence the anti-insulin antibody titres. Non-responders had significantly better metabolic results than the responders. Severe hypoglycaemic episodes decreased dramatically in both groups. Insulin requirements were comparable at time 0 and decreased initially in both groups. They remained low for the non-responders but returned to pre-implantation values for responders. Intraperitoneal insulin infusion led to a high immunogenetic response towards insulin in about half of the patients, leading to only moderately deleterious effects on metabolic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Prothrombin fragment 1 + 2 and thrombin-antithrombin III complex as markers of activation of blood coagulation in inflammatory bowel diseases.

OBJECTIVES AND METHODS: The aims of the present work were to assess the presence of thrombin generation in Crohn's disease and in ulcerative colitis by using the prothrombin fragment 1 + 2 and the thrombin-antithrombin III complex assays and to study the possible relationships between these markers and disease activity. RESULTS: Prothrombin fragment 1 + 2 and thrombin-antithrombin III complex were significantly raised in patients with Crohn's disease (n = 69) and with ulcerative colitis (n = 25) as compared with healthy controls (n = 50). In Crohn's disease these two markers of thrombin generation were correlated with the Van Hees index (P < 0.05 and P < 0.001, respectively); values were significantly different from controls even in the patient group displaying the lowest disease activity (P < 0.001). No correlation was found with tumour necrosis factor alpha and C-reactive protein; nevertheless patients with C-reactive protein less than or equal to 10 mg/l had significant lower values of prothrombin fragment 1 + 2 (P < 0.03). In ulcerative colitis prothrombin fragment 1 + 2 and thrombin-antithrombin III complex were significantly increased by comparison with controls, were higher in patients with pancolitis and correlated with C-reactive protein (P < 0.002 and P < 0.009, respectively). CONCLUSION: These data show that prothrombin fragment 1 + 2 and thrombin-antithrombin III complex are increased in inflammatory bowel diseases and suggest that thrombin generation might be an early event in their pathogenesis.

Adolescent↗
PubMed1995

Determination of free triiodothyronine by six different methods in patients with non-thyroidal illness and in patients treated with amiodarone.

We performed a methodological comparison of free triiodothyronine (FT3) estimates in patients with liver cirrhosis and renal failure. Patients were classified in terms of severity of illness on the basis of their total triiodothyronine, total thyroxine and reverse triiodothyronine profiles. FT3 levels, measured in direct dialysis, microchromatography, labelled analogue and two-step immunoextraction assays were significantly (P < 0.01) lower than the control group in all patient categories. However, FT3 measured by a labelled antibody radioimmunoassay was significantly reduced only in the most severely ill sub-group of patients. In a further group of patients on long-term amiodarone therapy for cardiac disease all FT3 methods, with the exception of the labelled antibody radioimmunoassay and an analogue method, yielded significantly (P < 0.01) reduced levels. A significant negative association between FT3 and subject age was demonstrated for all methods except the labelled antibody radioimmunoassay, and a weak but significant negative correlation between log thyrotropin and FT3 was only seen with this assay. Three methods demonstrated a correlation (P < 0.02) with albumin levels in patients with the 'low T3 syndrome'. In this group, albumin had a predictive value (P < or = 0.02) for four out of six assays as determined by stepwise variable selection. Our findings suggest that users of FT3 assays should exercise caution in interpreting results in non-thyroidal illness and amiodarone treated patients, as there are method-related differences in the profiles obtained.

Adult↗
PubMed1994

Thyroid hormone status and nutrient intake in the free-living elderly. Interest of reverse triiodothyronine assessment.

Fasting or hypercaloric diets are established methods of inducing low triiodothyronine (T3) levels that resemble the sick euthyroid syndrome in adults, but little is known on the mechanisms of this syndrome in the elderly. Decreasing T3 does not seem to be an unavoidable consequence of ageing, but the role of illness or other factors in this decline remains unclear. The aim of this work was to study the influence of nutritional factors on thyroid hormone levels in free-living elderly subjects. A 3-day dietary survey was conducted in 440 randomized subjects aged between 65 and 96. Cholesterol, apoproteins, prealbumin, hemoglobin, thyrotropin-free thyroxine (FT4), FT3 and reverse T3 (rT3) were assayed in each subject. Only 11 subjects had low FT3 levels, and they also had low levels of cholesterol, prealbumin and hemoglobin and a lower Folstein score compared to the rest of the population. Twenty-one subjects had isolated elevated rT3 levels, they were older and had significantly lower energy and fat intakes than the rest of the population. There was a clear reduction in FT3 levels and an increase in rT3 levels with age, although in the normal ranges, which occurred despite maintenance of a high-energy intake even in the oldest group. The FT3 level was lower in the subjects with poor health status, whereas high rT3 levels were associated with low energy intake in men. Stepwise regression showed that hemoglobin, age and prealbumin were the best predictors of FT3 levels, whereas age and energy intake were the main predictors of rT3 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Effects of amiodarone on thyroid hormonal profile. Updating based on new assay methods].

Amiodarone (A) treatment alters the levels of thyroid hormones. We investigated whether new hormonal assays are also altered by this drug. Thyroid function was determined in 21 patients chronically treated with A and in 30 controls. TSH was determined with a third generation assay. Free T3 and Free T4 levels were determined by 5 different immunoassays. Equilibrium dialysis (E.D.) was considered as the reference assay for FT3 and FT4. With this method FT3 is diminished, reverse T3 ans FT4 are increased whereas TSH remained normal. Only FT3 determined by an assay using a labelled monoclonal antibody (MAB) appears not modified by A. Other methods (chromatography, chemiluminescence and radioisotopic) give results in agreement with E.D. Some of these alterations may be explained by a marked increase in plasma levels of non esterified fatty acids. Hormonal changes induced by A are typically with all but one assays. Whatever the method used the determination of TSH remains necessary to avoid misinterpretation of the thyroid function tests in A-treated patients.

Aged↗
PubMed1993

[Evaluation of the participation of proinsulin in hyperinsulinism in patients with obesity and glucose intolerance].

The comparison of the results of two insulin assays, a RIA using a polyclonal antibody and a EMIA using two monoclonal antibodies in blood samples collected during an oral glucose load in normal, obese, glucose intolerant and type II diabetic patients indicated that hyperinsulinemia of obese and glucose intolerant patients is not associated to increased proinsulin/insulin ratio.

Adult↗
PubMed1993

[Assay of free thyroxine by immunoenzyme method in general diseases].

In non thyroid illnesses the degree of serum FT4 levels perturbation may be variable according to the assay used. The performance of a new FT4 immunoenzymatic assay (Enzymmum test, BMF) was evaluated in 78 euthyroid controls and in 99 sick patients with renal insufficiency, severe diabetes, hypoalbuminemia, severe general disease or under heparinate treatment. Results were compared to two RIA assays: by immunoextraction (CA2), known to be little disturbed by hypoalbuminemia and considered as a reference method, and by a labelled antibody (MAB, Amerlex) easier to use. In controls mean values and T4 L confidence intervalls were comparable with the three assays. In patients FT4 levels were diminished in case of renal insufficiency but the mean values obtained by BMF and CA2 did not differ. FT4 levels of heparinate treated patients were elevated with BMF and CA2. Generally patients are better classified as euthyroid with the CA2 assay (5.6% misclassification) than with BMF (11.2%) or MAB (12.4%), particularly in case of serious disease. A good linear correlation was found between the three methods. With the new BMF assay results were grossly comparable to those obtained by other assays. However the determination of FT4 levels alone appeared no sufficient to characterize the patients thyroid status.

Evaluation Studies as Topic↗
PubMed1993

[Evaluation of sensitivity of an assay: application to a third-generation thyrotropin (TSH) assay].

The concentration-specific smallest detectable difference (D) between two concentrations (i.e., the sensitivity) was determined from the results of within-run and run-to-run reproducibility studies of a third-generation thyrotropin assay. Only low concentrations were considered (range 0-0.3 m U/l). Assays were performed in singlet or in duplicate. Findings confirmed the value of the assay: the analytic detection limit approximated 0.005 mU/l and the functional detection limit was around 0.01 mU/l. Expressed as a percentage of the concentration, D% was under 20% for levels of less than 0.02 mU/l in within-run studies or of less than 0.03 mU/l in run-to-run studies. With concentrations in excess of 0.05 mU/l, D% was under 10% in within-run studies and slightly above 10% in run-to-run studies. These new detection thresholds for this assay should be taken into account when interpreting clinical results from a single run (TRH test) or from several runs (hormone replacement therapy or suppression test).

Humans↗