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Biomedical subjects

B Descomps

Publications and source records attributed to B Descomps.

At least 145 records · Page 8Linked to original sources
PubMed1979

[Postoperative analgesia by constant flow injection of lignocaine in obstetrical and gynecologic surgery].

154 surgical patients were given post-operative analgesia by peridural injection at a constant flow in the post-operative period after obstetric or gynecological surgery. These patients received 536.2 +/- 105.3 mu mol.h-1 (145.2 +/- 28.5 mg.h-1) of lignocaine for 46.97 +/- 15.56 h through a catheter omserted between L1-L2. The drug was given in concentrations which varied between: 27.7 to 18.5 m mol.l-1 (0.75 to 0.50 p. 100) depending on the age; and the volume varied between 17.5 to 30 ml.h-1 depending on the height. Satisfactory analgesia in 87 p. 100 of cases allowed all supplementary analgesia to be stopped. The only significant hemodynamic effect was a slight tachycardia (+ 15 p. 100). Two undesirable side effects were noted: a transitory but well-defined (type 2 or 3) motor paralysis, and an accumulation of plasma lignocaine (40 mu mol.l-1 (1.1 microgram.ml-1) at 48 h).

Analgesia↗
PubMed1978

Plasma acetate levels during hemodialysis.

Before dialysis, acetate levels in hemodialyzed patients (0.27--1.1 mmol/1) were more dispersed than in normal subjects (0.20--0.65 mmol/l) and the mean value of plasma acetate was slightly higher (0.52 mmol/l versus 0.31 mmol/l). Though dialysis conditions were almost identical, the acetate kinetics during hemodialysis were very different: in most subjects, plasma acetate concentrations reached a "plateau" (mean value 5.6 mmol/l) whereas in others a continuous rise was observed, suggesting that with patients having chronic renal failure there were important individual or occasional differences in the ability to metabolize acetate. The acetate loads per minute (or mass transfers) were calculated from the blood compartment with plasma values (plasma flow and concentrations), rather than from the dialysate and using the combined calculations (plasma and whole blood values). The results ranged between 2.4 and 4.1 mmol/min. A very important and rapid fall in arterial acetate concentrations occurs in the first 20 min after the end of the dialysis and proves the rapid turnover of the acetate in man.

Acetates↗
PubMed1978

Structural requirements for maximal inhibitory allosteric effect of estrogens and estrogen analogues on glutamate dehydrogenase.

The inhibition of glutamate dehydrogenase by estrogens, estrogen analogues or polyphenylethylene derivatives (about one hundred molecules, most of them having estrogenic or antiestrogenic activities) was measured. The efficiency of these compounds in inducing allosteric inhibition of the enzyme was compared and correlated to their chemical structure: an aromatic ring A, a free phenolic group in the region of carbon 3 of the steroid nucleus and a lipophilic substitution in the region of C-12, C-13 or C-17 were found to be the main structural features required for maximal efficiency on glutamate dehydrogenase. A tentative model for the relative orientation of the main inhibitor families is proposed. It accounts for most of the kinetic results and can be used as a tool for the selection of affinity labels directed towards the estrogen binding site of glutamate dehydrogenase.

Allosteric Site↗
PubMed1978

Affinity labelling of the estrogen binding site of glutamate dehydrogenase with iodoacetyldiethylstilbestrol. Selective alkylation of cysteine-89.

Iodoacetyldiethylstilbestrol was used as an affinity label to alkylate the estrogen binding site of bovine liver glutamate dehydrogenase. This reagent induced inactivation and alkylation of the enzyme. The non-alkylating analogues diethylstilbestrol and estradiol protected the enzyme towards alkylation. The apparent constant of alkylation was of the order of magnitude of I50 for the allosteric inhibition by diethylstilbestrol. These two results suggest that alkylation occurred at the estrogen binding site. The stoichiometry of alkylation was between one and two, depending on the experimental conditions. When the stoichiometry was found to be less than or equal to 1, 90% of the label was bound on cystein residues, 70% of which was carried by cysteine-89, a cysteine residue which is known to be inacessible to iodoacetamide in phosphate buffer in the same conditions of temperature and pH.

Affinity Labels↗
PubMed1977

Squalene epoxidase and oxidosqualene lanosterol-cyclase activities in cholesterogenic and non-cholesterogenic tissues.

Squalene epoxidase and oxidosqualene lanosterol-cyclase activities have been studied in normal mammalian cholesterogenic and non-cholesterogenic tissues. This paper describes the kinetic conditions of measurement of these two enzymatic acitivities and their results. Oxidosqualene lanosterol-cyclase is a widespread enzyme, present in all cholesterogenic and non-cholesterogenic tissues. However, the level of squalene epoxidase is very low in non-cholesterogenic tissues. However, the level of squalene epoxidase is very low in non-cholesterogenic tissues. The effects of subcellular fractionizing and of the physico-chemical state of squalene incubated in vitro on squalene epoxidase activity are discussed.

Animals↗
PubMed1977

[Rapid gas chromatographic method for determination of acetate in human plasma and hemodialysis baths (author's transl)].

A rapid and sensitive method for acetate determination in human plasma and in hemodialysis baths (dialysates) is going to become necessary owing to the extensive using of sodium acetate solution in hemodialysis. The gas chromatographic method reported here allows, in about 35 minutes, the precise and reproducible measurement of acetate concentrations ranging from 0.2 to 20 mmol/1. This method can be used to investigate the kinetics of acetate concentration variations in the blood of patients undergoing hemodialysis with sodium acetate solution and to evaluate the amount of acetate absorbed during this treatment.

Acetates↗
PubMed1977

Characterisation of an associate 17-beta-hydroxysteroid dehydrogenase activity and affinity labelling of the 3-alpha-hydroxysteroid dehydrogenase of Pseudomonas testosteroni.

The 3-alpha-hydroxysteroid dehydrogenase and the 3-beta-hydroxysteroid dehydrogenase of Pseudomonas testosteroni were purified to homogeneity by polyaerylamide gel electrophoresis using the following stages: DEAE cellulose chromatography, affinity chromatography on oestrone-aminocaproate sepharose and Sephadex gel filtration. The pure 3-alpha-hydroxysteroid dehydrogenase was completely devoid of 3-beta-hydroxysteroid dehydrogenase activity but could oxidize estradiol 17-beta at an appreciable rate. This activity accounts for about 40 per cent of the total 17-beta-estradiol dehydrogenase of the crude bacterial extract. Affinity labelling of pure 3-alpha-hydroxysteroid dehydrogenase was carried out using 5-beta-pregnane 3,20-dione-12-alpha-iodoacetate and 5-alpha-androstane 3-one-17-beta-bromoacetate. With both reagents, inactivation was obtained only in the presence of coenzyme, the substrate protected against inactivation and the enzyme was fully inhibited with covalent binding of 1 mole of reagent per mole of subunit suggesting an active site directed inhibition. Histidine and methionine were identified as the labelled aminoacid residues.

17-Hydroxysteroid Dehydrogenases↗
PubMed1977

[Plasma prolactin levels in normal children from birth to adolescence].

Plasma prolactin levels were determined by an homologous radio-immuno assay in normal children: in cord blood, at the first day of life, during childhood and along puberty. 1. In both sexes, there is a very important secretion of prolactin during the neonatal period. 2. Longitudinal studies make obvious a different pattern of plasma prolactin in boys and in girls at puberty.

Adolescent↗
PubMed1976

Affinity labelling of the estradiol-17 beta dehydrogenase from human placenta with substrate analogs.

Affinity labelling of the estradiol-17 beta dehydrogenase of human placenta has been performed using derivatives of estradiol-17 beta carrying alkylating groups in nine different positions on the steroid nucleus. The active-site-directed character of the inhibition is confirmed by the following observations: the affinity labels are substrates or competitive inhibitors, the enzyme is protected against inactivation and alkylation by the substrate and by the coenzyme, the stoichiometry of the alkylation is two moles of inhibitor per 68 000 g of enzyme (dimer). The alkylation of a histidine residue which is fast and extensive when the alkylation side chain is on the C-3 carbon atom, is dramatically decreased when alkylating side chain is shifted towards rings B and D. These results allow the location of this histidine in the vicinity of ring A and probably on the beta face of the steroid nucleus. The reactivity of a cysteine located on the active site was quite different, showing increasing alkylation when the alkylating substituent of the affinity labels was shifted from C-3 to C-16 of the steroid nucleus. The correlation of this result and that obtained using an alkylating analog of NAD (3-chloroacetyl-pyridine-adenine dinucleotide) indicates that this cysteine is located in the catalytic region of the active site, at the junction of the ring D of the steroid nucleus with the nicotinamide moiety of the coenzyme.

Acetamides↗
PubMed1976

[Secretion of gonadotropins during sleep. Changes during secondary amenorrheas].

4 females with secondary amenorrheas underwent sleep polygraphic recordings together with blood samples for measurements of LH, FSH and GH, 3 normal females served as controls. Among normal subjects LH and FSH secretion showed a pulsating pattern around the time of ovulation, appearing as secretory episodes throughout the night, without any relationship with sleep stages. In amenorrheas, 3 types of abnormalities could be identified: the first was a lack of secretory episodes of LH and FSH associated with an abnormal pattern of GH (9 subjects). The second was an hypersecretion of LH and a decrease of FSH secretion together with a normal secretion of GH in 4 subjects with a Stein-Leventhal syndrome. The last one was an hypersecretion of LH and FSH together with a normal pattern of GH in a subject with an early menopause. These results are discussed according to the present data on the part of neurotransmission in the regulation of ovulation and the 2 types of sleep. Furthermore secretory abnormalities of LH and FSH together with a disconnection between GH secretion and the stages of sleep lead to question the possibility of interrelationships in the secretory mechanisms of these different hormones.

Adolescent↗