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Biomedical subjects

F Gasser

Publications and source records attributed to F Gasser.

At least 19 recordsLinked to original sources
PubMed2000

Concordance of eight kits for antithyroid peroxidase autoantibodies determination.

Numerous methods are proposed to quantify antithyroid peroxidase autoantibodies. No standardization exists but most assays use the standard MRC 66/387 with a calibration factor. Costs of the tests vary between the different kits. We evaluated the concordance of eight peroxidase autoantibodies assay kits in two centres, using a panel of sera from 269 subjects: controls (n=100), patients with autoimmune thyroid disease (n=77; Graves' disease, Hashimoto's thyroiditis), patients with non-autoimmune thyroid disease (n=69; nodular goiter, differentiated thyroid carcinoma) and individual sera with thyroglobulin antibodies only (n=23). The concordance between the eight methods was high, ranging from 88.3% to 98.8% with the total panel of sera. The majority of assays demonstrated high diagnostic performance. We encountered some false-positive results at borderline positive levels, and the nonrecognition of some sera by competitive assays.

Autoantibodies↗
PubMed1998

Evaluation of Elecsys free triiodothyronine assay: relevance of age-related reference ranges.

OBJECTIVE: This study aimed at evaluating Elecsys free triiodothyronine (FT3) assay performed on an Elecsys 2010 system, while paying special attention to age relationship in euthyroid subjects. DESIGN AND METHODS: FT3 levels were measured in 149 euthyroid control subjects aged between 2 and 92 years old, 33 hyperthyroid and particular euthyroid patients: female in the last 3 months of pregnancy (n = 30), nonthyroidal ill hospitalized in medical (NTlm, n = 31), or intensive care units (NTlc, n = 31) and amiodarone-treated (n = 27). RESULTS: FT3 was inversely related to age in controls (r = -0.67). Three reference ranges were used: below 20 years 4.5-9.0 pmol/L, between 20 and 60 years 3.9-7.2, and over 60 years 2.4-6.5. Compared to age-matched controls, FT3 decreased in pregnancy, NTlm, NTlc, and amiodarone groups. Use of age-related reference ranges improved the specificity markedly in amiodarone patients and to a lesser extent in NTlm and TClc patients. CONCLUSIONS: The reliability of the Elecsys FT3 assay was found to be satisfactory for clinical use, when the age of patients was taken into account.

Adolescent↗
PubMed1998

Characterization of FSH-regulated genes isolated by mRNA differential display from pig ovarian granulosa cells.

The present authors have isolated FSH-regulated genes from primary granulosa cell cultures with or without Follicle Stimulating Hormone (FSH) treatment using mRNA differential display. mRNA differential display consists of amplification of partial sequences of cDNAs (150-400 bp) corresponding to 3' ends of cellular messenger RNAs, and thus, generates 3' expressed sequence tags (3' ESTs). Five thousand cDNA bands were examined, among which the present authors have isolated and sequenced 16 different FSH-regulated products. These sequences were compared with those available in databases. Three of the sequences showed similarity to identified genes from other species (bovine NADH dehydrogenase subunit 4, Xenopus chromosome sequence-associated polypeptide E and transformation-sensitive protein IEF SSP) and four others with human ESTs. Regulation of the corresponding genes has been checked by RT-PCR since most of these are expressed at a low level. FSH-regulation was confirmed for 12 mRNAs (four down- and eight up-regulated). The present authors have also mapped 12 of these ESTs on porcine chromosomes regions using a somatic cell hybrid panel.

Animals↗
PubMed1998

Improved specificity of a new direct assay for urinary cortisol: application in corticoid treated patients.

Twenty four hours urinary free cortisol (UFC) excretion has been determined in 35 eucortisolic control patients, in seven of them before and after tetracosactide (Synacthen) stimulation and in 18 patients treated by anti-inflammatory steroids. Results of the new direct Immunotech RIA (DIm) were compared to those of the INCSTAR RIA kit with (ECA) or without methylene chloride extraction (DCA). In controls DIm UFC (106.2+/-45.8 nmol/24h) was significantly lower than DCA UFC (397+/-119 nmol/24h) and than ECA UFC (127+/-49 nmol/24h). After tetracosactide stimulation, median of DCA/DIm ratio decreased from 3.61 to 1.88 whereas ECA/DIm ratio did not change significantly (1.31 to 1.06). In treated patients most DCA and ECA results were over the upper limit of controls but only 5 DIm results were increased. DIm assay showed good specificity and practicability and may be used with benefit in the evaluation of the adrenal gland function.

Anti-Inflammatory Agents↗
PubMed1997

A first catalog of genes involved in pig ovarian follicular differentiation.

As a first step toward the characterization of genetic expression in pig ovaries, we have selected 238 clones by differential hybridization from a pig granulosa cell cDNA library, using probes prepared from RNA extracted from either untreated or FSH-treated cells and, in order to generate expressed sequence tags (ESTs), we have performed 3' and 5' single-pass sequencing of these clones. Sequences of the 3' end of the 167 clones that produced informative sequence data were first compared with each other, revealing a redundancy level of 21%. Sequences from the 136 unique clones were analyzed for similarities with sequence data included in Genbank and EMBL databases. Among these unique clones, 54 (40%) matched significantly with sequences from either Genbank of EMBL: 4 with known genes in pig, 35 matched with previously reported human genes, and 15 with other mammalian genes. Eighty-two clones (60%) showed no significant match with any gene or DNA sequence in the Genbank and EMBL databases and thus may represent new pig transcripts.

Animals↗
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

Identification and characterization of the pqqDGC gene cluster involved in pyrroloquinoline quinone production in an obligate methylotroph Methylobacillus flagellatum.

Pyrroloquinoline quinone is a prosthetic group of bacterial methanol dehydrogenases as well as some alcohol and glucose dehydrogenases. Genes involved in pyrroloquinoline quinone production have previously been cloned from the representatives of the alpha and gamma subdivisions of the Proteobacteria. We report identification and the sequence of the pqqDGC gene cluster in the obligate methylotroph, Methylobacillus flagellatum, which belongs to the beta subdivision. The deduced products of the pqq genes from M. flagellatum appear to be more similar to their counterparts from non-methylotrophic species of the gamma subdivision than to a facultative methylotroph of the alpha subdivision. A non-polar mutation in pqqG was constructed and resulted in a strain impaired in growth on methanol. This mutant accumulated a detectable amount of intracellular pyrroloquinoline quinone, but in contrast to the wild type, did not excrete pyrroloquinoline quinone into the culture medium. The possible role of PqqG is discussed.

Amino Acid Sequence↗
PubMed1996

Sequence and functional analysis of an Escherichia coli DNA fragment able to complement pqqE and pqqF mutants from Methylobacterium organophilum.

A 7361 kb fragment of E coli chromosomal DNA able to complement pqqE and pqqF mutants of Methylobacterium organophilum has been sequenced. Five open reading frames (ORF) have been identified. Four ORFs (102, 103, 106 and 107), belong to a single transcription unit. They are separated by a transcription termination site from a fifth ORF (ORF109). Polypeptides of 28, 85 and 82 kDa encoded by ORFs 102, 103 and 106 respectively were visualised in maxi-cell experiments. Both ORF106 and ORF107 are required for complementations of pqqE and pqqF mutants from M organophilum. The polypeptides encoded by ORFs102, 103 and 107 have no homologies with the products of pqq genes previously sequenced from Acinetobacter calcoaceticus, Klebsiella pneumoniae, and Methylobacterium extorquens AM1. The polypeptide encoded by ORF106 shows homology with the pqqF gene product of K pneumoniae, and seems to belong to a family of zinc proteases. The sequence of ORF109 is identical to the sequence of the gadB gene of E coli encoding for a glutamate decarboxylase.

Amino Acid Sequence↗
PubMed1996

Expression of messenger ribonucleic acids of insulin-like growth factor binding protein-2, -4, and -5 in the ovine ovary: localization and changes during growth and atresia of antral follicles.

In the sheep as in many mammalian species, growth and atresia of antral follicles are characterized, respectively, by a decrease and a high increase in the intrafollicular levels of insulin-like growth factor binding proteins of less than 40 kDa (IGFBPs < 40 kDa), mainly IGFBP-2, -4, and -5. The objective of this study was to investigate whether such changes are associated with changes in follicular expression of the corresponding mRNA. For this purpose, ovaries were recovered from ewes slaughtered at the end of follicular phase (i.e., 30 h after progestagen sponge removal; control ewes) or at 24 h, 36 h or 72 h after hypophysectomy (hypox) performed 30 h after sponge removal. The expression of mRNA of IGFBPs of less than 40 kDa (IGFBPs < 40 kDa mRNA) was studied in ovine antral follicles from control and hypox ewes by in situ hybridization using [35S]-labeled human IGFBP-2, -4, and -5 cRNA as probes. In control ewes, IGFBP-2 mRNA was mainly expressed in granulosa as a gradient in healthy follicles, the expression being higher in granulosa cells close to the basal membrane than in granulosa cells bordering the antrum and within the cumulus. The level of IGFBP-2 mRNA was lower both in granulosa cells close to the basal membrane and in those bordering the antrum from small follicles than in the corresponding compartments of granulosa cells from large healthy follicles (p < 0.05). In healthy follicles, IGFBP-4 and -5 mRNA were mainly expressed in thecal cells. No change in level of IGFBP-4 mRNA was observed between small and large follicles, whereas the level of IGFBP-5 mRNA tended to be lower in thecal cells from large compared to small follicles (p = 0.055). In atretic follicles, expression of IGFBPs < 40 kDa mRNA strongly increased in granulosa (IGFBP-2 and -5, p < 0.01) and in thecal cells (IGFBP-2 and -4, p < 0.01). In hypox ewes, the chronology of changes in expression of follicular IGFBPs < 40 kDa mRNA and in intrafollicular levels of the corresponding proteins was studied during atresia of large antral follicles. Early atresia of large follicles was associated with a strong decrease in intrafollicular estradiol levels (p < 0.001); an increase in intrafollicular levels of IGFBP-2, -4, and -5 (p < 0.001) an increase in both IGFBP-2 (p < 0.001) and -5 (p < 0.01) mRNA expression in granulosa and thecal cells; but no changed in IGFBP-4 mRNA expression. Late atresia of large follicles was associated with a further decrease in intrafollicular estradiol levels (p < 0.01); a further increase in intrafollicular levels of IGFBP-2, -4, and -5 (p < 0.001); an increase in IGFBP-4 (p < 0.01) and -5 (p < 0.05) mRNA expression in theca and granulosa, respectively; a decrease in IGFBP-5 mRNA expression in theca (p < 0.05); but no further increase in IGFBP-2 mRNA expression. Overall, these data suggest that the decrease and the increase in expression of mRNA of follicular IGFBPs < 40 kDa during follicular growth and atresia, respectively, are involved in the decrease and the increase in intrafollicular levels of the corresponding proteins. Moreover, the increases in expression of follicular IGFBPs < 40 kDa during atresia of large follicles in hypophysectomized ewes followed a specific time course, the increase in IGFBP-2 and -5 mRNA expression being early than the increase in IGFBP-4 mRNA expression.

Animals↗
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↗
PubMed1995

Protein kinase C inhibition of in vitro FSH-induced differentiation in pig granulosa cells.

In granulosa cells, growth factor IGF I plays a major role in both growth and differentiation, acting through an autocrine/paracrine mechanism, and its production is regulated by FSH, via cyclic AMP (cAMP). As protein kinase C is also involved in granulosa cell function, we investigated the possibility that its activation could balance the positive effects of FSH. Using pig granulosa cells cultured in vitro, we studied the effects of protein kinase C activation by tetradecanoylphorbol acetate (TPA) on IGF I mRNA level. We also checked morphological modifications, cAMP production and steroidogenesis at the P450 side chain cleavage mRNA and progesterone levels. Our data demonstrate that protein kinase C activation antagonizes the in vitro FSH-induced differentiation, particularly morphological modifications and accumulation of IGF I mRNA. These inhibitory effects on FSH responses suggest that there could be a balance between protein kinase A and protein kinase C pathways in regulating differentiation in pig granulosa cells.

Animals↗
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↗