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Biomedical subjects

J Davignon

Publications and source records attributed to J Davignon.

At least 199 records · Page 11Linked to original sources
PubMed1980

Effect of acute and chronic administration of calcitonin on serum glucose in patients with Paget's disease of bone.

The effects of an acute injection of synthetic salmon calcitonin (sCT) and human CT (hCT) and of long term (4-month) administration of sCT on serum glucose levels were investigated in eight patients with Paget's disease of bone. The results obtained demonstrate a small but statistically significant rise in serum glucose after a single sc injection of synthetic hCT. However, the serum glucose level was not increased after 4 months of daily administration of synthetic sCT to our pagetic patients. Our results also substantiate the clinical observation that long term administration of CT does not cause clinical diabetes or significantly change fasting blood glucose concentration. Our results are also consistent with the view that the effect of CT administration on glucose metabolism is related to the secondary hypocalcemia.

Aged↗
PubMed1980

Cyclic nucleotides and platelet aggregation in hypertensive rats with ectopic pituitary tumor.

The transplantable pituitary tumor MtT-F4 secretes several pituitary hormones in Fisher rats, resulting in severe cardiovascular disease with a mineralocorticoid type of hypertension and hyperlipidemia. The mineralocorticoid-dependent hypertension possesses particular characteristics in humans and animals. It was of interest to study cyclic nucleotides and platelet aggregation in the Fisher rat with an MtT-F4 tumor in order to evaluate the type of abnormalities in this form of hypertension. The effect of administration of an anti-hyperlipidemic agent (clofibrate) was also evaluated. The animals bearing the tumor showed anomalies of platelet aggregation induced by the divalent cation ionophore A 23187, in that there was an apparent enhanced change in shape and a decreased rate of aggregation. Although the basal concentrations of cyclic nucleotides were normal, as were the increases in cyclic GMP induced by epinephrine, cyclic AMP concentrations increased less (about 2.7-fold) in response to PGE1 than in control Fisher rats (about 6-fold). A decreased stimulation of adenylate cyclase activity by PGE1 was observed in platelets of tumor-bearing rats. The administration of clofibrate to sham-operated animals somewhat lowered the increase of cyclic AMP in response to PGE1. In tumor-bearing animals, clofibrate considerably reduced plasma lipids, blood pressure and the degree of abnormalities in platelet aggregation and cyclic AMP in platelets. Thus, the abnormalities of platelet aggregation and regulation of cyclic nucleotides in the mineralocorticoid-type of hypertension induced by MtT-F4 were opposite to those found previously in spontaneous hypertension in rats. Hyperlipidemic and hypertensive rats with MtT-F4 tumor may provide a useful model for the study of the relatioship between hyperlipidemia and hypertension.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1979

Hyperlipoproteinemia induced by a transplantable pituitary tumor in the rat.

The MtT-F4 tumor, a transplantable pituitary tumor of rats, induces significant hyperlipidemia in male Fisher 344 rats. The increasive hypercholesterolemia was accompanied by hypertriglyceridemia only in the first month of tumor implantation. Clofibrate feeding inhibited the development of hypercholesterolemia and maintained normal serum triglyceride levels. In contrast to the changes in lipoprotein cholesterol distribution and profile found in experimental hyperlipidemia induced by high fat and cholesterol feeding, the hypercholesterolemic tumor-bearing rats showed no accumulation of cholesterol in the very low density and intermediate density lipoproteins, and no appearance of a new class of lipoprotein, B-VLDL. An HDLc-like lipoprotein appeared as hypercholesterolemia developed. Increased amounts of cholesterol were deposited in the aorta. The effects are attributed to the lipolytic hormones secreted by the tumor and antagonism to their action by clofibrate.

Animals↗
PubMed1979

Fatty acid profile of major lipid classes in plasma lipoproteins of patients with Friedreich's ataxia-demonstration of a low linoleic acid content most evident in the cholesterol-ester fraction.

Studies were undertaken to further characterize plasma lipids and lipoprotein abnormalities in Friedreich's ataxia. The high density lipoprotein (HDL) apo AI/AII ratio was quantitated by densitometry and found to be normal. The free to esterified cholesterol ratio in HDL was lower in Friedreich's ataxia because of a reduction in the amount of free cholesterol in this lipoprotein class. The fatty acid profile of the cholesteryl-ester (CE) fraction was markedly deficient in linoleic acid (18:2) in both total plasma and HDL. There was a compensatory increase in saturated acids. The HDL phospholipid (PL) fraction also showed a reduction in the proportion of 18:2 with a concomitant increase in stearic (18:0) and oleic acid (18:1) while the HDL triglyceride (TG) fraction showed only an increase in palmitoleic (16:1) and oleic acids. Feeding of soya lecithin rich in 18:2 failed to increase significantly the 18:2 content of HDL-CE and HDL-PL but lowered the percentage of 16:1 and 18:1 in all 3 lipid classes of HDL. Although the total plasma CE fatty acid profile was perturbed in Friedreich's Ataxia, total plasma PL and TG fatty acid patterns were unaffected. Among the plasma lipoprotein fatty acid profiles, that of the low density lipoprotein (LDL) was most affected, then that of the HDL. The very low density lipoprotein (VLDL) fatty acid composition showed an increase in 16:1 and a decrease in 18:2 which were entirely corrected by lecithin feeding. These results suggest the existence of a metabolic defect in the incorporation of 18:2 into chylomicron phospholipids within the intestinal mucosa.

Adolescent↗
PubMed1979

Erythrocyte membrane lipids in Friedreich's ataxia.

In a study of the lipid composition of erythrocyte membranes in Friedreich's ataxia, the concentration of the major membrane components (phospholipids, cholesterol and protein) in ataxic patients, family members, and control subjects were found to be the same. The total fatty acid distribution was also normal. However, an altered distribution of phospholipid classes in erythrocytes was noted (an increase of PI + PS and a decrease of PE in Friedreich's ataxia patients).

Adult↗
PubMed1979

Effect of acute administration of salmon and human calcitonin on blood urate and renal excretion of uric acid in patients with Paget's disease of bone.

The sc injection of salmon calcitonin (CT) (100 MRC U) or human CT (50 MRC U) to Pagetic patients reduces the plasma urate concentration and increases the renal excretion of uric acid. This effect is independent of the natriuretic, phosphaturic, or glycosuric actions of CT and is not due to the transient increment of the glomerular filtration rate noted after CT administration. Our results suggest that the hypouricemia observed during CT treatment is related, at least in part to a direct action on the renal handling of uric acid.

Aged↗
PubMed1979

Experimental hyperlipidemia in rats.

Implantation of MtT-F4 tumor, a mammotropic tumor that secretes large quantities of ACTH, GH and prolactin, into male Fisher rats induced the development of hyperlipidemia. Free fatty acid, triglyceride and cholesterol levels in the plasma were significantly increased at 31 days after tumor implantation. Blood glucose and glycerol levels remained normal, while uric acid concentration in the blood was significantly decreased. The concentrations of the serum lipoproteins were significantly increased, while, only small changes in the distribution of the serum lipids and the composition of the lipoproteins were observed. Following stimulation of isolated adipose tissue cells with ACTH, the lipolytic response and the accumulation of cyclic AMP was higher in cells derived from the rats with the tumor, although the accumulation of cyclic GMP was not different from control adipocytes. Further, when the isolated adipose tissue cells were stimulated with dibutyryl cyclic AMP no difference was observed between the control and tumor bearing groups. Clofibrate administered in the diet resulted in a complete elimination of the tumor effect on serum triglycerides and to a great extent prevented the rise in serum cholesterol. The tumor-induced increase in the concentration of the high density lipoproteins was not affected, but the elevation of the d less than 1.063 lipoproteins was not affected, but the elevation of the d less than 1.063 lipoproteins was partially reversed. The increased lipolytic response and accumulation of cyclic AMP following stimulation by ACTH was not altered in adipocytes derived from tumor bearing rats. However, clofibrate treatment resulted in a significantly greater accumulation of cyclic GMP in fat cells stimulated with ACTH from both control and tumor bearing rats. Clofibrate in the diet did not alter the levels of GH or prolactin or serum lipids in the control rats nor were the elevated hormone levels of the tumor bearing rats changed.

Adipose Tissue↗
PubMed1978

Lipid and lipoprotein secretion following portacaval shunt in swine.

Lipid and lipoprotein secretion were studied over 24 h in normal and portacaval shunted (PCS) fasting miniature swine after an infusion of Triton WR-1339 and [3H]amino acid mixture. The plasma triglyceride secretion rate and the secretion of triglyceride, total cholesterol and protein in the very low density lipoprotein fraction (VLDL) were linear for about 9 h after Triton. No net catabolism of the VLDL appeared to take place over the 24 h. Due to large variation, differences in the absolute secretion rates of plasma triglyceride and of the VLDL constituents could not be shown. However, the secretion of VLDL cholesterol in the PCS group appeared to be lower than that of the sham group when corrected for metabolic body size and plasma volume.

Animals↗
PubMed1978

Development of hyperlipidemia associated with increased lipolytic response of isolated adipose tissue cells following prolonged stimulation by an ectopic pituitary tumor.

Implantation of MtT-F4 tumor, a mammotropic tumor that secretes large quantities of ACTH, GH and prolactin, into male Fisher rats induced the development of hyperlipidemia. Free fatty acid, triglyceride and cholesterol levels in the plasma were significantly increased at 31 days after tumor implantation. Blood glucose and glycerol levels remained normal, while uric acid concentration in the blood was significantly decreased. The lipolytic response of isolated adipose tissue cells to ACTH was significantly higher in cells derived from rats bearing an MtT-F4 tumor for 31 days than from their corresponding controls. However, the activity of adenylate cyclase in fat cells stimulated with ACTH was not significantly higher in cells derived from tumor bearing rats than in cells from control rats.

Adenylyl Cyclases↗
PubMed1978

Plasma lipids and lipoproteins in Friedreich's ataxia and familial spastic ataxia--evidence for an abnormal composition of high density lipoproteins.

A systematic study of plasma lipids and lipoproteins was carried out in 11 cases of Friedreich's ataxia and 6 cases of familial spastic ataxia (Charlevoix-Saguenay disease) using 11 healthy normolipidemic volunteers of comparable age and sex as controls. No differences were noted in the fatty acid profile of the total lipid fraction, in the total cholesterol and phospholipids or in the percentage distribution of the individual phospholipid classes. The triglycerides were significantly higher in Friedreich's ataxia, but remained within the normal range. Although no systematic abnormalities could be detected in the electrophoretic pattern of plasma lipoproteins or in the apolipoprotein profile on polyacrylamide gel electrophoresis, major differences were found in the high density lipoprotein (HDL) fraction. Their total amount was reduced and their composition was abnormal in both neurological diseases. In Friedreich patients, the relative proportion of cholesterol and triglycerides was increased while the relative protein content was greatly reduced. In Charlevoix disease, a similar abnormality was seen except for the excess of triglycerides. The proportion of phospholipids in HDL was the same in the three groups of patients. In addition, the low density lipoprotein (LDL) fraction was slightly reduced in both diseases. This anomaly of the HDL fraction could indicate that the HDL apolipoprotein moiety has a greater affinity for cholesterol and triglycerides in Friedreich's ataxia than its normal counterpart.

Adolescent↗
PubMed1977

The effect of portacaval shunt on plasma lipids and lipoproteins in swine.

Plasma lipids and lipoprotein composition and distribution were studied in fasted miniature swine prior to and at 5 and 19 weeks following portacaval shunt surgery or a sham operation. Plasma triacylglycerol and cholesterol levels were significantly reduced in the portacaval shunt swine at 5 weeks. These reductions were accompanied by significant decreases in the plasma very low density lipoprotein (d less than 1.006), low density lipoprotein (d = 1.02-1.07) and high density lipoprotein (d = 1.09-1.21) levels. The very low density lipoprotein were shown depleted in lipids and the low density lipoprotein was a cholesterol-depleted, triacylglycerol-enriched particle. No changes in the composition of the high density lipoprotein were observed. These reductions and changes in composition were maintained until killing at 19 weeks post-surgery.

Animals↗