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Biomedical subjects

P Lefèbvre

Publications and source records attributed to P Lefèbvre.

At least 37 records · Page 2Linked to original sources
PubMed1995

Glucose handling, diabetes and ageing.

The relationship between ageing and glucose homeostasis is still an open debate. In fact, the mechanisms by which glucose metabolism is progressively impaired with increasing age are not completely understood. In the present report we have reviewed the possible mechanisms (impaired insulin secretion and action, role of the environmental factors) which may lead to the impairment in glucose handling associated with ageing. We also point out that not all aged subjects are glucose intolerant; in fact, it has been suggested that only those aged subjects who present more than one pathological finding do in fact develop impaired glucose handling.

Aging↗
PubMed1992

Insulin effects on glucose kinetics in non-insulin-dependent diabetic patients with secondary failure to hypoglycaemic agents: role of different modes and rates of delivery.

OBJECTIVES: This study aimed at investigating the effects of pulsatile and continuous insulin delivery on glucose kinetics in non-insulin-dependent (type 2) diabetic patients with secondary failure to oral hypoglycaemic agents. METHODS: Seven type 2 diabetic patients underwent a 585 minute glucose-controlled glucose intravenous infusion using the Biostator. The endogenous pancreas secretion was inhibited by somatostatin. Three experiments were performed in each patient on different days and in random order. In all cases, glucagon was replaced (58 ng/min). The amounts of insulin infused were: a) 0.15 mU/kg x min continuously; b) 0.20 mU/kg x min continuously and c) 1.0 mU/kg x min in 2 minute pulses every 13 minutes. D-[3-3H]-glucose infusion allowed determination of glucose kinetics. RESULTS: Infusion of identical amounts of insulin (A vs C) demonstrated that pulsatile insulin delivery exerted greater metabolic effects (higher glucose infusion rate and, mainly at the beginning of the experiment, lower endogenous glucose production) than continuous infusion; furthermore pulsatile insulin delivery (C) exerted metabolic effects similar to those of a greater dose of insulin (B) infused continuously. CONCLUSIONS: In type 2 diabetic patients with secondary failure to oral hypoglycaemic agents, pulsatile insulin delivery exerts greater metabolic effects than continuous hormone delivery.

Aged↗
PubMed1992

Effects of mild-to-moderate hyperglycaemia per se on glucose production and uptake in the elderly.

OBJECTIVES: In order to better understand the mechanisms responsible for the diminished glucose tolerance that occurs in the elderly, the present study aimed at investigating the effect of mild hyperglycaemia on glucose production and uptake in a group of aged subjects. For comparison, a group of young subjects was simultaneously investigated. METHODS: Seven aged (71.8 +/- 2.3 yrs) and seven young (25.5 +/- 1.7 yrs) healthy non-obese subjects underwent two hyperglycaemic glucose-clamps having as targets plasma glucose levels 7.5 and 10.0 mmol/L. Contemporary infusion of D-[3-3H]-glucose allowed determination of glucose turnover parameters in basal conditions and during the clamps. Endogenous pancreatic secretion was inhibited by somatostatin (8.3 micrograms/min) while glucagon (67 ng/min) and insulin (0.15 mU/kg/min) were replaced by exogenous infusions. RESULTS: In basal conditions, glucose uptake (12.9 +/- 0.5 vs 14.4 +/- 0.4 mumol/kg/min; p < 0.05) and glucose metabolic clearance rate (2.58 +/- 0.15 vs 3.35 +/- 0.10 ml/kg/min; p < 0.01) were lower in elderly vs young subjects. In the hyperglycaemic glucose-clamps, we observed, in the elderly subjects, the persistence of a greater glucose production during mild (7.5 mmol/L) (11.6 +/- 0.4 vs 9.7 +/- 0.2 mumol/kg/min; p < 0.005) but not moderate (10 mmol/L) (3.5 +/- 0.1 vs 3.4 +/- 0.1 mumol/kg/min; NS) hyperglycaemia. In contrast, glucose-induced glucose uptake and glucose metabolic clearance rate were similarly affected by glucose infusions in both groups of subjects. Moreover, in elderly but not in young subjects, basal glucose disappearance rate was significantly negatively correlated with fasting plasma glucose levels (r = -0.84; p < 0.01). CONCLUSIONS: In the basal state, glucose uptake and glucose metabolic clearance rate are slightly impaired in elderly, compared to young subjects. Furthermore, in the elderly, endogenous glucose production is less suppressed by mild hyperglycaemia i.e. 7.5 mmol/L, than it is in young people. Such impairment in the inhibition of endogenous glucose production is not seen when blood glucose attains 10 mmol/L. We suggest that impairment in glucose tolerance in the elderly results from both reduced glucose uptake (in basal conditions) and excessive glucose production (at mild hyperglycaemic levels).

Adult↗
PubMed1990

Evidence for a hyperglycaemia-dependent decrease of antithrombin III-thrombin complex formation in humans.

In the presence of increased levels of fibrinopeptide A, decreased antithrombin III biological activity, and thrombin-antithrombin III complex levels are seen in diabetic patients. Induced-hyperglycaemia in diabetic and normal subjects decreased antithrombin III activity and thrombin-antithrombin III levels, and increased fibrinopeptide A plasma levels, while antithrombin III concentration did not change; heparin was shown to reduced these phenomena. In diabetic patients, euglycaemia induced by insulin infusion restored antithrombin III activity, thrombin-antithrombin III complex and fibrinopeptide A concentrations; heparin administration had the same effects. These data stress the role of a hyperglycaemia-dependent decrease of antithrombin III activity in precipitating thrombin hyperactivity in diabetes mellitus.

Adult↗
PubMed1990

Magnesium and glucose homeostasis.

Magnesium is an important ion in all living cells being a cofactor of many enzymes, especially those utilising high energy phosphate bounds. The relationship between insulin and magnesium has been recently studied. In particular it has been shown that magnesium plays the role of a second messenger for insulin action; on the other hand, insulin itself has been demonstrated to be an important regulatory factor of intracellular magnesium accumulation. Conditions associated with insulin resistance, such as hypertension or aging, are also associated with low intracellular magnesium contents. In diabetes mellitus, it is suggested that low intracellular magnesium levels result from both increased urinary losses and insulin resistance. The extent to which such a low intracellular magnesium content contributes to the development of macro- and microangiopathy remains to be established. A reduced intracellular magnesium content might contribute to the impaired insulin response and action which occurs in Type 2 (non-insulin-dependent) diabetes mellitus. Chronic magnesium supplementation can contribute to an improvement in both islet Beta-cell response and insulin action in non-insulin-dependent diabetic subjects.

Animals↗
PubMed1990

[Medicine and physicians in the works of Georges Simenon].

When reading the novels of Georges Simenon, one is surprised by the high prevalence of doctors in medicine, general practitioners, specialists or university professors. With a few remarkable exceptions, most of these figures appear under a most positive angle: serenity, seriousness, devotion, scientific knowledge, social and professional success. We suggest that the origin of this phenomenon must be searched in the life of the novelist himself. Indeed, the young Simenon has been in contact with a major city hospital, the "Hôpital de Bavière" in Liège, where he was serving the early morning mass and was accompanying the priest to the dying, and with students in Medicine renting accommodation at his parents' house. Simenon had looked to study medicine and had to change his plans being told at the age of 15 that his father, suffering angina pectoris, would not survive more than 2-3 years. The prognosis was correct and this greatly impressed Simenon. At the age of 40, the novelist was given for himself the same diagnosis and prognosis, obviously erroneous this time... This event led him to write his first autobiographical work "Pedigree". All his life long, Simenon has had a major interest for Medicine, entertaining a significant personal collection of medical books and journals and having personal contacts with many physicians, some of them illustrious. We believe that all this has had a significant impact on the topics and the characters of his novels.

France↗
PubMed1990

[Seroconversion to bovine respiratory syncytial virus in goats with pneumonia in Zaire].

Coupled sera were taken among goats suffering from pneumonia in Zaire. The presence of antibodies to bovine syncytial respiratory virus was investigated by a seroneutralization test. Out of 26 animals, 9 already had antibodies at the time of the first blood sampling, 9 presented a seroconversion and 8 remained seronegative during the two months of observation. These results suggest it would be useful to study the frequency of the infection of small ruminants with this virus and its clinical and economical impact in Central Africa.

Animals↗
PubMed1987

Beta-endorphin infusion restores acute insulin responses to glucose in type-2 diabetes mellitus.

To address the possibility that an abnormality in pancreatic beta-endorphin activity might contribute to abnormal insulin secretion in diabetes mellitus, we studied the effects of beta-endorphin infusion on islet function in diabetic patients. The iv infusion of human beta-endorphin at a dose of 0.5 mg/h for 2 h in type-2 non-insulin-dependent diabetic patients (n = 12) raised plasma insulin and glucagon levels and slightly but significantly lowered plasma glucose concentrations. beta-Endorphin infusion also resulted in reappearance of a clear-cut acute insulin response to glucose, while second phase insulin release was increased and glucose disposal accelerated. Acute insulin and glucagon responses to arginine were not increased by beta-endorphin, suggesting that the effect of the opioid on the B cells of the diabetic patients is specific for glucose. An intraislet abnormality of opioid peptides action and/or secretion may play a role in the disturbances of insulin secretion in patients with type-2 diabetes mellitus.

Arginine↗