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Biomedical subjects

M Lambert

Publications and source records attributed to M Lambert.

At least 379 records · Page 21Linked to original sources
PubMed1982

[Partial progressive lipoatrophy. A new case-report (author's transl)].

A new case of lipoatrophic diabetes with some peculiar features is reported. The disease was acquired, with onset at approximately thirty years of age, and partial, involving only the face and the upper limbs. The authors were able to observe the successive occurrence of the various symptoms: progressive lipoatrophy, hyperinsulinism, insulin-resistant diabetes, major lipid disturbances, and finally renal failure with a nephrotic syndrome and high blood pressure. Nosologic borders and physiopathology are discussed with a review of the literature.

Adult↗
PubMed1982

Specific photoaffinity crosslinking of [125I]cholecystokinin to pancreatic plasma membranes. Evidence for a disulfide-linked Mr 76 000 peptide in cholecystokinin receptors.

In rat pancreatic plasma membranes, preincubated with [125I]cholecystokinin-33 (CCK-33) and washed free of unbound tracer, the irradiation by UV light induced the irreversible binding of radioactivity to high molecular weight peptides as shown by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS) and autoradiography. This was not observed when the membranes were preincubated in the simultaneous presence of [125I]CCK-33 and of either an excess of unlabelled CCK-8 or of guanosine 5'-(beta, gamma-imido)-triphosphate. The radioactivity was mostly crosslinked with a Mr 96,000 peptide and peptide species of Mr greater than 200,000, after SDS solubilization in the absence of beta-mercaptoethanol. Peptide reduction with beta-mercaptoethanol converted the high molecular weight radioactive species into a Mr 76,000 peptide that contained as much as 65% of the radioactivity crosslinked. The Mr 76,000 peptide appears, therefore, to be a disulfide-linked constituent of rat pancreatic cholecystokinin receptors.

Animals↗
PubMed1982

Effect of 2 anti-arrhythmic drugs aprindine and moxaprindine on the replication capacity of murine and human haemopoietic cells.

Aprindine, a potent anti-arrhythmic agent, occasionally seems responsible for agranulocytosis. In order to study its potential haematological toxicity, 3 different in vitro tests were used: (a) the capacity of human and mice bone marrow to incorporate tritiated thymidine (3HTdR), (b) the capacity of stimulated human blood lymphocytes to incorporate 3HTdR and (c) the capacity of human granulocyte-macrophage stem cells to form colonies in agar. For all these tests aprindine was found to be toxic at concentrations close to the clinical therapeutic serum concentration. Moxaprindine, chemically very close to aprindine exhibits also an anti-arrhythmic activity. It was examined in the same tests in parallel with the study af aprindine. Moxaprindine also exhibited haematological toxicity in the tests but at a significantly higher concentration, approximately twice that of aprindine. Assuming that these in vitro tests are relevant to the in vivo haematological toxicity, moxaprindine could be considered a clinically safer anti-arrhythmic agent than aprindine.

Animals↗
PubMed1982

Delayed sulfhemoglobinemia after acute dapsone intoxication.

A case of acute Dapsone intoxication due to voluntary ingestion of 3 g of this drug as a suicide attempt is described. A severe methemoglobinemia developed, accompanied by intense cyanosis, dyspnea, headache, and nausea. Subsequently, significant sulfhemoglobinemia responsible for prolonged cyanosis was observed, as well as mild hemolytic anemia. Relapses of methemoglobinemia after methylene blue treatment required repeated administration of the reducing agent. The need of a careful follow-up for several days in this type of intoxication is emphasized.

Adult↗
PubMed1982

[Prolidase and manganese deficiency. Apropos of a case: diagnosis and treatment].

Prolidase deficiency, transmitted on an autosomic recessive mode upsets skin healing and facilitates the occurrence of chronic cutaneous ulcerations. A 36-year-old woman has been followed since the age of 12 for ulcerations and erythematous erysipelatoid plaques of the lower limbs. Two episodes of agranulocytosis were induced by intake of sulfonamides at the age of 17. The same accident had been observed in her aunt. As the aetiological research of ulcers was negative, a prolidase deficit was suspected. The diagnosis is ascertained by the existence of an immunopeptiduria of 5 mmol/24 hours (normally absent). The predominating dipeptides are glycilproline and phenylalanine proline. R-hydroxyproline dipeptide were present at a lesser degree. Urinary hydrolysis showed elevation of free proline (x 10) and hydroxyproline (x 6). Dosage of erythrocytes prolidase evidenced an activity 2 p. 100 of the normal in one case and 55 p. 100 and 49 p. 100 in the parents. Treatment by cofactors of prolidase (vitamine C and manganese) reduced immunopeptiduria, suppressed inflammatory outbreaks and allowed a transient cicatrisation. This tenth case of prolidase deficiency underlines the character of the disease: recurrent ulcers (7/10), erysipelatoid plaques (3/10), ecchymosis (4/10), telangiectatic scars (7/10), edema (1/10), early canitias (1/10). Partial correction by cofactors evokes a prolidase deficiency by inactivation of the enzymes activating systems.

Adult↗
PubMed1981

Determining steps in the regulatory GTPase cycle of rat pancreatic adenylate cyclase.

The time course of activation and deactivation and the degree of activation at steady state [Ea]/[Etot] of adenylate cyclase, in semi-purified rate pancreatic plasma membranes, were compatible with a simple two-state model with three rate constants, so that [Ea]/[Etot] = k+1/(k+1 + k2 + k-1). The hormone CCK-8 increased k+1 with GTP in a dose-dependent manner, from 0.2 to 10.9 min-1; k-1 increased from 0.01 to 0.3 min-1, i.e. in proportion, but k2 was unaltered at 7 min-1, so that [Ea]/[Etot] increased 15-fold, from 4 to 61%. A similar activation was obtained after cholera toxin pretreatment by a different mechanism. The toxin pretreatment exerted a major inhibitory effect on the value of k2 and on the corresponding GTPase activity. A pretreatment at the high cholera toxin concentration (10 micrograms/ml) exerted two additional effects that became evident when p[NH]ppG rather than GTP was used as activating nucleotide: (a) a relatively large increase in k-1 from an unmeasurably low control value to 0.3 min-1, and (b) a four-fold increase in the p[NH]ppG activation rate, k+1. This contrasted with the action of CCK-8, which increased k-1 and k+1 in proportion.

Adenylyl Cyclases↗
PubMed1981

Distinct effects of the C-terminal octapeptide of cholecystokinin and of a cholera toxin pretreatment of the kinetics of rat pancreatic adenylate cyclase activity.

(1) The kinetic parameters of rat pancreatic adenylate cyclase were evaluated, using GTP, p[NH]ppG or GTP gamma S as nucleotide activator, cholecystokinin as peptide hormone, and GDP beta S and dibutyryl cyclic GMP as inhibitors of guanosine triphosphate and CCK-8, respectively. The time courses of activation and the degree of activation at steady state (EA/ETOT) were compatible with a simple two-state model of activation-deactivation based on a pseudo-monomolecular activation process (rate constant kappa+1), and a deactivation process (rate constant kappa off) that included, depending on the activating nucleotide, the hydrolysis of GTP (rate constant kappa 2) and/or the dissociation of the intact nucleotide (rate constant kappa-1), so that EA/ETOT = kappa+1/(kappa+1 + kappa 2 + kappa-1). (2) The hormone CCK-8 increased the value of kappa+1 with GTP dose-dependently, from 0.2 to 10.9 min-1. The value of kappa-1 increased 0.01 to 0.3 min-1 but the value of kappa 2 was unaltered at 7 min-1, so that EA/ETOT increased 15-fold, from 4% to 61%. (3) A cholera toxin pretreatment at 30 micrograms/ml allowed also a large increase in EA/ETOT with GTP (up to 51%) but the underlying mechanism was different. It consisted of a 14-fold decrease in the kappa off value of the GTP-activated enzyme (from 7 min-1 to 0.5 min-1) that corresponded to a reduction in GTPase activity. When testing the system with p[NH]ppG, two added effects of the cholera toxin pretreatment were observed: a 4-fold increase in the value of kappa+1 (from 0.2 to 0.8 min-1) and the occurrence of a significant 0.3 min-1 value for kappa-1.

Adenylyl Cyclases↗
PubMed1981

Similar characteristics of guanine nucleotide regulatory sites involved in adenylate cyclase activation, specific GTPase activity, and cholecystokinin binding in rat pancreatic plasma membranes.

The specificity of guanine nucleotide regulatory site(s) of rat pancreatic plasma membranes involved in adenylate cyclase activation, basal and cholecystokinin (CCK)-stimulated specific GTPase activity, and [125I]-CCK-33 binding was documented. The Km (for GTP) and Ki (for other nucleotides) of basal and CCK-8-dependent GTPase showed similar specificity, decreasing in the order GTP gamma S approximately GTP approximately Gpp[NH]p greater than ITP greater than GDP beta S greater than UTP, suggesting the identity of basal and CCK-stimulated GTPase activities. The same potency order for these nucleotides was obtained when tested as activator (Ka) or inhibitor (Ki for GDP beta S) of adenylate cyclase, in the presence of CCK-8. The IC 50 of these nucleotides on the binding of [125I]-CCK-33 indicated a similar specificity for nucleotide binding sites interacting with CCK receptors (GTP gamma S approximately Gpp[NH]p approximately GTP greater than ITP approximately GDP beta S greater than UTP). In membranes preactivated with 0.3 micron CCK-8 and 30 micron Gpp[NH]p or GTP gamma S, then washed free of hormone and unbound nucleotide, persistent effects of the nonhydrolyzable nucleotides were observed on the three activities tested. The present data indicate that the guanine nucleotide regulatory units involved in adenylate cyclase activation, GTPase activity and CCK binding have similar properties in rat pancreatic plasma membranes.

Adenylyl Cyclases↗