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Biomedical subjects

G Chabrier

Publications and source records attributed to G Chabrier.

At least 19 recordsLinked to original sources
PubMed1989

Linkage analysis of hereditary thyroid carcinoma with and without pheochromocytoma.

The use of polymorphic DNA segments as markers for the gene for the multiple endocrine neoplasia (MEN) syndrome, type 2a, allows the identification of family members at high risk for developing medullary carcinoma of the thyroid and other tumors, especially pheochromocytoma. Several families have also been identified in which medullary thyroid carcinoma is inherited, but pheochromocytoma is not seen. We have analysed 18 families, 9 with MEN 2A and 9 with medullary carcinoma of the thyroid without pheochromocytoma, with probes specific for the pericentromeric region of chromosome 10 and conclude that the mutations for the two presentations are closely situated. Genetic heterogeneity of the susceptibility locus was not seen among this sample of 18 families. The genetic mutation for medullary carcinoma was in disequilibrium with the marker alleles of the two closely linked probes, IRBPH4 and MCK2. These data suggest that different mutant alleles of the same gene or closely linked mutations account for the variation in penetrance of pheochromocytoma in families with hereditary medullary thyroid carcinoma.

Adolescent↗
PubMed1989

[Effects of subcutaneous administration of sandostatine (SMS 201.995) in 18 cases of thyroid medullary cancer].

Recent studies have suggested that somatostatin could reduce calcitonin plasma levels (CT) in normal subjects and in medullary thyroid carcinoma (MTC). The aim of this study was to examine the usefulness of the somatostatin analog, sandostatine (SMS 201.995) in MTC with elevated residual CT levels post-thyroidectomy with or without metastases. 18 patients (17-64 years, 12 men and 8 women) with CT greater than 850 pg/ml (N less than 150 pg/ml) and with metastases in 12 cases, were studied. MTC was sporadic in 11 cases, familial in 4 cases and of undefined form in 3. Initial posology was 300 micrograms/d of sandostatin (3 injections/day). It was then increased by 300 micrograms/d every 9 day till a maximum of 1500 micrograms/d. Treatment duration was 37 days in 11 cases and 60 days in 7 cases. Plasma CT and carcinoembryonic antigen levels (CEA) were measured before treatment and at the end of each dosage plateau. Morphologic evaluation of metastases was done at 0, 30, 60 days. 7/18 patients were reevaluated 2 to 8 months after with drawal of sandostatine. Treatment was well tolerated. Flushes improved in 4 out of 5 cases but diarrhea in only 2 out of 9 patients. Sandostatine was without any effect on plasma CEA. Heterogenous responses were observed for plasma CT levels (CT decreases greater than 20% in 8/18 patients when 900 to 1500 micrograms/day were administered). Patients were subdivised into 3 groups according to CEA levels and presence or absence of metastases. Group A (n = 9) had elevated CEA levels (greater than 10 mg/ml) and metastases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

[Disorders of plasma trace elements in diabetes. Relation to blood glucose equilibrium].

The influence of glycaemic control and diabetes characteristics on plasma concentrations of magnesium, zinc, copper, selenium, rubidium and bromine has been evaluated in 44 diabetics (30 insulin-dependent, 14 non insulin-dependent), and the results obtained were compared to those of 309 control subjects of the same mean age. Diabetics had reduced plasma magnesium concentrations (P less than 0.01) but normal erythrocyte magnesium levels. Plasma zinc and selenium concentrations were reduced, whereas those of copper were increased and those of bromine and rubidium were normal. Correlation between glycaemic control, evaluated by measurement of glycosylated haemoglobin levels, and each of the parameters studied was only demonstrated with magnesium in insulin-dependent diabetics (r = -0.561; P less than 0.02). No correlation was found with the other clinical or anthropometric characteristics of the diabetic patients studied. Diabetes seems to be associated with numerous abnormalities of plasma trace elements and magnesium, but the mechanism of these abnormalities has not yet been elucidated. A decrease in zinc and selenium concentrations and an increase in copper concentrations might be additional factors of atherogenicity.

Adult↗
PubMed1988

Intestinal ammonium production in the rat: the role of the colon, small intestine, and circulating glutamine.

The intestinal ammonium production and the intestinal uptake of circulating glutamine were investigated in anesthetized intact rats and rats with resected small intestine or colon by simultaneous measurements performed on portal and arterial blood. It was shown that ammonium release into the portal blood by the small intestine is of equal magnitude to that released by the colon, and that circulating glutamine participates in ammonium production by the small intestine. Increased levels of circulating glutamine induced by its i.v. infusion to intact rats were not accompanied by an increase in intestinal ammonium production.

Ammonia↗
PubMed1987

[Study of salivary cortisol using radioimmunological assay. Diagnostic value].

Salivary cortisol levels reflect the biologically active "free" fraction of blood cortisol. The authors describe the results obtained with the aim of a radio-immunoassay commercial serum cortisol kit, without prealable extraction in different physiological and pathological situations. Salivary cortisol determination appears performant both in nycthemeral studies and in stimulation or freination tests.

Adult↗
PubMed1986

Effects of 2,4-dinitrophenol on renal ammoniagenesis in the rat.

Injection of anesthetized rats with the uncoupling agent, 2,4-dinitrophenol (2,4-DNP) 10 or 20 mg/kg induced a systemic hyperammonemia unaccompanied by blood acid-base status changes and related to an increased release of ammonium from the kidney into the renal vein. Ammonium excretion into the urine did not increase. The renal uptake of circulating glutamine rose. The antiepileptic drug sodium valproate (VPA), a short-chain, branched fatty acid, had the same effects on rat and man. These findings suggest that VPA stimulates renal ammoniagenesis by the same mechanisms as 2,4-DNP.

2,4-Dinitrophenol↗
PubMed1986

Arterial ammonemia changes of renal origin induced in the rat by acid and alkaline diets.

The aim of this study was to investigate the influence of acid and alkali food supplementation on systemic ammonemia to explain the hyperammonemia previously observed in rats fed a high protein diet. In normal rats, arterial ammonia concentration significantly increases after 4 days of HCl-supplemented diet. Following a NaHCO3-enriched food, there is only a slight but not significant decrease in arterial ammonia level. These changes occur before any variation in arterial acid-base status and are of renal origin. Indeed, there is a positive linear correlation (r = 0.946; P less than 0.001) between arterial ammonia level and the ammonia concentration difference between the renal vein and artery (which varies proportionally to the urinary ammonium excretion). Hindquarter uptake and intestinal release of ammonia do not significantly participate in the arterial ammonia changes observed. Following HCl-enriched diets, increased renal glutamine uptake, enhanced hindquarter glutamine release, and perhaps decreased intestinal glutamine uptake occur simultaneously. In conclusion, acid and alkali food supplementation intervenes on the renal ammonia release into the circulation with concomitant arterial ammonemia changes.

Ammonia↗
PubMed1986

[Ultra-sensitive TSH levels: an aid in the screening for amiodarone-induced thyroid dysfunction].

Amiodarone modifies thyroid hormone secretion and hypothyroidism occurs in some cases. The latter diagnosis is often difficult and is of particular importance in these patients as it may have serious consequences for the heart. Early diagnosis is therefore essential but difficult because of the induced hyperthyroxinemia with maintenance of euthyroidism and a hypotriiodothyronemia. The diagnostic performance of an ultrasensitive method of measuring TSH (TSH-U), capable of distinguishing hyper and euthyroidism were compared with standard thyroid function tests and TSH stimulation with TRH in 50 patients treated with amiodarone. Only 6 of the 14 patients with hyperthyroxinaemia had TSH-U values in the hyperthyroid range: only one of these patients had an increased triiodothyronine. In 2 cases the THS-U was low but the T4L was normal. In 4 patients, increased TSH-U allowed diagnosis of latent or patent hypothyroidism. There was a close correlation between results of the TRH stimulation test and those of the TSH-U in all cases. This test may therefore be used as an initial screening test for thyroid dysfunction in patients on amiodarone and is simple, reliable and relatively cheap to perform. It makes it unnecessary to measure all thyroid hormonal parameters and the TRH test simultaneously.

Amiodarone↗
PubMed1986

[The ultrasensitive determination of TSH permits the prediction of the response to TSH in the TRH test].

A new ultrasensitive TSH immunoradiometric assay (IRMA) using two monoclonal antibodies is now able to distinguish between euthyroid and hyperthyroid patients. The aim of this study was to compare data given by ultrasensitive basal TSH (IRMA) and by the response of TSH to TRH test considered until now as the more reliable test in case of mild or atypical hyperthyroidism. Basal plasma TSH levels were determined in euthyroid (n = 80), hyperthyroid (n = 30), hypothyroid (n = 14) and pituitary deficient patients (n = 8) before and 30 minutes after a TRH test (250 micrograms i.v.). A close linear correlation was found between basal and post-stimulative TSH levels. Normal TSH response ranged from 2 to 22 uU/ml. The sensibility and the specificity of these two parameters appeared comparable in the case of primary dysthyroidism; on the contrary basal TSH levels were not sufficient for the diagnosis of central hypothyroidism. In conclusion, excepted for pituitary deficiency, basal plasma TSH (IRMA) levels are accurate and sufficient in the evaluation of the thyroid function and make the TRH-test useless.

Humans↗
PubMed1985

[Treatment of severe hyperthyroidism by plasma exchange. Clinical and biological efficacy. 8 cases].

The effectiveness of plasmapheresis was evaluated in 8 patients with severe thyrotoxicosis of diverse origin and clinical manifestations, who underwent a total of 22 plasma exchanges. The method proved rapidly effective in controlling the symptoms in 6 cases. No adverse reaction was noted. In all patients plasma exchanges significantly reduced plasma concentrations of total thyroxine and triiodothyronine and of thyroxine-binding globulin, without effect on free thyroxine and triiodothyronine fractions. The satisfactory clinical results obtained can only be explained by displacement of thyroid hormones from the intracellular compartment. The hormonal variations observed were proportional to the initial hormone concentrations, to the amount of thyroxine-binding globulin removed and to the plasma volume purified. It is concluded that plasmapheresis rapidly extracts thyroid hormones and is therefore useful in the treatment of acute severe thyrotoxicosis.

Adult↗
PubMed1985

Decrease of valproate-induced hyperammonemia in normal subjects by lipid ingestion.

Sodium valproate (VPA), a branched short-chain fatty acid, always causes a hyperammonemia of renal origin in fasting man. The intake of medium-length, straight-chain fatty acids abolishes the VPA-induced hyperammonemia, and VPA free fraction increases concomitantly. Accordingly, fatty acids could be useful in preventing and treating hyperammonemia-accompanied stuporous states which are complications of VPA medication.

Ammonia↗
PubMed1985

Adaptation of hepatic ammonia metabolism after chronic valproate administration in epileptics treated with phenytoin.

The effects of phenytoin (PHT) on the modifications of ammonia (NH+4) metabolism caused by sodium valproate (VPA) are here studied in order to identify the drug combinations susceptible of evoking stuporous states in epileptics, a rare condition attributed to a hyperammonemic encephalopathy induced by VPA. During chronic treatment with PHT or VPA-PHT, the acute injection of VPA increases the kidney's output of NH+4. During chronic PHT treatments, the acute injection of VPA modifies the liver's NH+4 metabolism and the arterial hyperammonemia is high (mean = 90 mumol/l). During chronic VPA-PHT treatments, the acute injection of VPA does not affect the hepatic NH+4 metabolism, suggesting that adaptation occurs, and the arterial hyperammonemia is moderate (mean = 60 numol/l). Disturbances of the hepatic adaptive mechanisms may explain certain complications observed during multiple-drug regimens.

Adaptation, Physiological↗
PubMedDate not supplied

[Hyperthyroidism and immune hemolytic anemia following amiodarone therapy].

We report the cases of two patients who, after prolonged amiodarone therapy developed hyperthyroidism and immune haemolytic anaemia. Antibodies were of the IgG type and non-specific at elution. A search for other causes of haemolytic anaemia with positive Coombs' test gave negative results. Antiamiodarone antibodies have recently been discovered; they reflect an immunological disturbance due to this drug and might be responsible for some of the undersirable effects of amiodarone. In our patients, hyperthyroidism and haemolytic anaemia were induced by a dual mechanism: accumulation of amiodarone and induction of an effect of this drug on the immune system.

Aged↗