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Biomedical subjects

L Mejean

Publications and source records attributed to L Mejean.

At least 37 records · Page 2Linked to original sources
PubMed1983

Modifications in apoprotein C composition of very low density lipoproteins in type IV hyperlipoproteinemic subjects after dietetic triglyceridemia reduction.

Variations in peptide composition of apoprotein C from very low density lipoproteins were studied in 10 type IV hyperlipoproteinemics, before and after triglyceridemia normalization through appropriate diet. The subjects were sensitive to carbohydrates or alcohol : a reduction or elimination of the inducing nutrient led to a decrease in serum triacylglycerol levels, correlated with an increase in the proportion of apo CII and a decrease in the proportion of apo CIII1. Apo CIII2 was not affected. This led to an increased ratio, apo CII/apo CIII1. The percentage of variation of different lipid (triacylglycerols and cholesterol) and protein (apoproteins CII, CIII2) parameters were also studied.

Adult↗
PubMed1982

Growth hormone responses to the stimulation of hypothalamic glucoreceptors in diabetic retinopathy. Effects of catecholamine precursors and dopamine antagonists.

The effects of the stimulation of glucoreceptors located at the level of the lateral hypothalamic nuclei and sensitive to intracellular glucose deprivation on growth (GH) release are well documented in the monkey. In this study the effect of a reproducible hypoglycemic stimulatory procedure was controlled by continuously monitoring blood glucose (BG) levels in normal subjects and in a series of 120 diabetic patients. In contrast to control subjects, GH responses to similar hypoglycemic nadirs were not reproducible in diabetics (with or without diabetic retinopathy). The infusion of levodopa, precursor of both norepinephrine (NE) and dopamine, during BG decline rendered the GH response to hypoglycemia consistently reproducible. To investigate the site of action of levodopa, a group of diabetics were pretreated with a centrally active dopamine antagonist, metoclopramide hydrochloride. The pattern of GH release was similar in both groups. These data suggest that in diabetes the interaction of levodopa and adequate stimulation of hypothalamic glucoreceptor systems is mediated by an NE transmission.

Adult↗
PubMed1981

Correlations between the apoprotein C composition of very-low-density lipoproteins and triglyceridemia in subjects with type IV hyperlipoproteinemia.

The protein composition of apoprotein C regarding peptides CII, CIII1, and CIII2 has been studied in VLDLs in 59 normal or hypertriglyceridemic subjects. The percentages of the peptides found in each subject were correlated with serum triacylglycerol levels. There are very good correlations between the proportion of VLDL apo CII and triglyceridemia (r = -0.63) and between the proportion of CII1 and triglyceridemia (r = 0.66). The proportion of apo CII decreases as triacylglycerol level increases, whereas the proportion of apo CII1 increases under the same conditions. The percentage of apo CII2 varies in the same way as does apo CII, but to a lesser degree. The apo CII/CIII1 and apo CIII2/CIII1 ratios decrease as triglyceridemia increases. In contrast, the apo CII/CIII2 radio, though reduced, is not significantly modified. Mechanisms are reviewed that could lead to changes in apoprotein C in subjects with hyperlipoproteinemia, and the possible relationship with lipoprotein lipase activity is discussed.

Apolipoproteins↗
PubMed1979

[Study of lipid metabolic coefficient K2 in patients with hyperlipoproteinemia type IV before and after reduction of triglyceride level by adapted diet therapy].

An intravenous fat tolerance test (IV FTT) was performed in a group of patients with type IV hyperlipoproteinemia before and after reduction of triglyceride level, the latter is obtained through a diet adapted to the nutritional sensitivity, body weight remaining constant. Before the diet the increase in cholesterol (CT) and triglycerides (TG) was related in both obese and non-obese patients to an increase in very-low-density lipoproteins (VLDL), while other lipoprotein fractions were not affected. In these patients, K2 is significantly lower than in controls whatever the nutritional sensitivity. However, K2 is lower in obese patients than in patients with normal weight, VLDL-CT and VLDL-TG are tremendously reduced by the relevant diet and K2 is constantly and significantly increased, although it does not reach a normal value in obese subjects. There is a highly significant correlation between VLDL-TG levels and K2 in obese and non-obese subjects. Several physiopathological explanations are discussed to account for the variation of K2 according to TG levels. The results obtained support the view that the K2 defect is secondary to the hyperlipoproteinemia.

Adult↗
PubMed1978

[Stability of lipid and protein composition of very low-density lipoproteins during the storage after freezing of whole serum and isolated lipoproteins (author's transl)].

The lipid and protein composition of lipoprotein is now regarded with great interest for the identification of hyperlipoproteinemias. Because this relatively time-consuming study cannot be envisaged currently in clinical services, it seems useful to analyse a storage procedure which does not affect the composition of very-low density lipoproteins, whose proportion is very important among subjects with type IV hyperlipoproteinemia. Two studies were considered, one using whole sera stored at -20 degrees C and one using very low-density lipoproteins held in the same conditions. The lipid composition was determined for triglycerides and cholesterol concentrations of total proteins, proteins soluble in tetramethylurea (apoprotein C, "arginine-rich fraction", and apoprotein D), and peptides CII, CIII1 and CIII2 of apoprotein C. For both procedures considered, no significant changes were seen in lipid and protein composition for periods as long as 8 weeks.

Apolipoproteins↗
PubMed1977

Interstitial gamma irradiation by 198Au of the pituitary in diabetic retinopathy. Selective growth hormone blockade and ocular results.

Pituitary interstitial irradiation by stereotaxic implantation of a gamma pointemitter was performed in 110 patients with progressing diabetic retinopathy. Reduction of growth hormone secretion peaks was delayed, but was consistent and selective in all cases controlled by somatotropin stimulation test, while other pituitary secretions remianed unchanged in all but five cases. In 31 patients who had no associated photocoagulation, long-term postoperative assessment showed significant improvement of hemorrhages and intrarentinal new vessels with preservation of visual acuity. Preretinal vascular proliferation (except when treatable by photocoagulation), extensive retinitis proliferans, and macular deterioration are contraindications. This technique represents a new approach in the functional pituitary neurosurgical treatment of diabetic retinopathy and differs from all other procedures that result in a more or less complete hypophysectomy.

Body Weight↗
PubMed1977

[Characterization of lipase activity in a yeast of the genus Rhodotorula (Rh. rubra)].

Lipase activity of whole cells of Rh. rubra has been localized in a particular fraction rich in walls and in isolated cell walls. The enzyme activity has been determinated with olive oil and the triglyceride fraction of olive oil as substrats. Gas chromatography of fatty acids and triglycerides isolated after enzyme hydrolysis shows that the action of Rh. rubra is not only limited to a simple hydrolysis of the substrate. The triglyceridase activity level is dependent of the phosphate content of the culture medium.

Cell Wall↗
PubMed1976

[The influence of glucagon on post-heparin plasma lipolytic activity in normal rats and in rats with diabetes induced by alloxan injection].

The authors compared the effect of glucagon on the post-heparinic lipolytic activity in normal and alloxan induced diabetic rats. Within their experimental conditions, it was considered that an injury of the cell stimulates a decrease of the glucagon-stimulating activity on the lipoprotein lipase: this hormone does not seem to have a direct action on the PHLA but an indirect one by the way of the insulin secretion it induces.

Animals↗
PubMed1975

[Comparison of blood sugar measured by Hoffman's, glucose oxidase and dextrostix technics during the oral glucose tolerance test].

The venous blood sugar has been measured in 384 adult subjects, between 20 and 60 years if agem during two oral glocose tolerance tests, with three methods: Hoffman's method, Glucose-oxidase method, and assay with reflectance meter (DRM). A good correlation was found with all methods (erg = 0,6 at 60 mn after load); however, the results given by the DRM were lower. So, in spite of its practical and economical advantages, the DRM can neverbe used for the diagnosis of an anomaly in the OGTT results. This method is a good one in emergency situations and in mass screening for diabetes.

Adult↗