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Biomedical subjects

R H Eckel

Publications and source records attributed to R H Eckel.

119 records · Page 7Linked to original sources
PubMed1981

Insulin and adipose tissue lipoprotein lipase activity in humans.

Insulin may be important in regulating adipose tissue lipoprotein lipase in the rat. Insulin appears to be necessary for the maintenance of enzyme activity in adipose tissue in humans since it is decreased in untreated diabetes and returns to normal with anti-hyperglycemic therapy. Other than this permissive role of insulin in maintenance of adipose tissue LPL activity in humans, there is little evidence that insulin, by itself, plays a primary role in the regulation of adipose-tissue lipoprotein lipase in man.

Adipose Tissue↗
PubMed1980

Postpartum thyrotoxicosis in a patient with Graves' disease. Association with low radioactive iodine uptake.

A patient with previously diagnosed Graves' hyperthyroidism had a transient episode of thyrotoxicosis three months postpartum. This was associated with a diffusely enlarged thyroid gland, a rise in antithyroid microsomal antibody titer, a 24-hour radioactive iodine uptake (RAIU) of 1%, and an aspiration biopsy specimen suggestive of chronic lymphocytic thyroiditis. An alternative cause for the depressed RAIU was not discovered. This case would suggest that patients with previously diagnosed Graves' disease can have thyrotoxicosis without an enhanced RAIU and that the postpartum thyrotoxic syndrome may involve an immunologic injury causing a release of performed thyroid hormone.

Adolescent↗
PubMed1979

Gastric inhibitory polypeptide enhanced lipoprotein lipase activity in cultured preadipocytes.

Fat feeding stimulated the release of gastric inhibitory polypeptide (GIP) without concomitant insulin secretion. Since antilipolytic effects of GIP have been demonstrated and the uptake of triglyceride fatty acid by adipose tissue postprandially is a process reciprocally regulated with lipolysis, a stimulatory role of GIP on adipose tissue lipoprotein lipase activity may be present. After cultured preadipocytes were incubated for 2 h with GIP, the release of lipoprotein lipase activity into the culture medium and the total cellular activity present in acetone-ether powders of cells were measured. GIP stimulated significant increases in the lipoprotein lipase activity released into the culture medium and in cells. A dose response relationship was strongest for the effect of GIP on the enzyme activity in extracts of acetone-ether powders of the cells. The increased lipoprotein lipase activity produced by GIP could provide a mechanisms for clearance of chylomicron triglyceride after feeding in man.

Adipose Tissue↗
PubMed1977

Platelet-latelet-.

Two patients with thrombotic thrombocytopenic purpura were seen. Aspirin, dipyridamole, and sulfinpyrazone were administered to patient 1 after splenectomy, and administration of high-dose prednisone and methylprednisolone failed to induce remission. The platelet count rose, but the patient had a relapse when the dipyridamole dose was tapered. This condition responded to an increase of the drug, and the patient obtained a long-lasting remission. A splenectomy was not performed on patient 2, and all three platelet-inhibiting drugs, together with prednisone, were given. This resulted in a prompt remission that has been sustained for 29 weeks. Morphologic changes in the peripheral blood smear remained for several weeks after other features of the disease had resolved. Thus, in both cases, platelet-inhibiting drugs appeared to induce a remission.

Adult↗
PubMedDate not supplied

The cornea and disorders of lipid metabolism.

Disorders of lipid metabolism, either hyperlipidemia or hypolipidemia, are associated with the formation of corneal opacities. Corneal arcus, the most commonly encountered peripheral corneal opacity, is frequently associated with abnormal serum lipid levels, but may occur without any predisposing factors. Reports also have linked corneal arcus with alcoholism, diabetes mellitus and atherosclerotic heart disease. Unilateral arcus is a rare entity that is associated with carotid artery disease or ocular hypotony. Diffuse corneal opacities associated with hypolipidemic disorders such as LCAT deficiency, fish eye disease and Tangier disease, may be the initial manifestation of these disorders and puts the ophthalmologist in a position to make an early diagnosis. Corneal arcus, along with a central corneal opacity, is seen in Schnyder's crystalline stromal distrophy. The association of the disorder with a dyslipidemia remains controversial. A review of lipid metabolism, corneal arcus and several disorders of lipid metabolism that affect the cornea are presented.

Alcoholism↗
PubMedDate not supplied

The role of insulin and body fat in associations of physical activity with lipids and lipoproteins in a biethnic population. The San Luis Valley Diabetes Study.

It has been postulated that the positive effects of physical activity on high density lipoprotein cholesterol (HDL-C) and HDL-C subfraction 2 (HDL-C2) are mediated through insulin action because increased activity lowers insulin levels and lower insulin levels are associated with higher HDL-C. These relations were evaluated in a rural population of Hispanic and non-Hispanic white (NHW) adults in Colorado. Included were 138 men and 152 women with normal glucose tolerance confirmed by World Health Organization criteria. Total physical activity was assessed by 7-day recall interviews. No significant associations were observed among women. Among men, activity was inversely associated with fasting insulin (r = -0.17, p less than 0.05). From analysis of covariance models including the interaction term activity x ethnicity, total HDL-C was 43.4 mg/dl (95% confidence interval [CI] = 39.1, 47.7) in the low tertile of activity and 50.4 mg/dl (95% CI = 46.3, 54.5) in the high tertile for NHW men, after adjustment for fasting insulin, fasting glucose, body mass index (BMI), waist to hip ratio (WHR), and age. For Hispanic men, adjusted HDL-C was 43.4 mg/dl (95% CI = 38.6, 48.2) and 49.1 mg/dl (95% CI = 44.0, 54.2) in the low and high tertiles, respectively. Adjusted HDL-C2 levels were 52% higher in the most compared with the least active NHW men, whereas there was no difference by activity for Hispanic men. Higher adjusted mean levels of HDL-C3 were observed for the high compared with the low activity tertile in both ethnic groups. Ethnicity-specific models showed that for NHW men, activity explained 12% (p = 0.01), fasting insulin explained 5% (p = 0.05), and BMI explained 6% (p = 0.04) of the variability in total HDL-C, after adjustment for fasting glucose, WHR, and age. These models confirmed that effects of insulin and body fat did not explain the observed associations between activity and total HDL-C and its subfractions.

Adipose Tissue↗
PubMedDate not supplied

Insulin-mediated increases in the HDL cholesterol/cholesterol ratio in humans.

The role of insulin in the regulation of lipoprotein cholesterol distribution was studied in 18 human volunteers who were of normal weight, normolipemic, and glucose-tolerant. We used the euglycemic clamp technique and made comparisons with six saline-infused controls. While total cholesterol and low density lipoprotein cholesterol levels fell similarly by 6 hours in both groups (p = NS), there was a greater decrease in triglyceride levels (p less than 0.02) but less decrease in high density lipoprotein cholesterol levels (p less than 0.02) in the insulin-infused group. These changes resulted in both a higher high density lipoprotein cholesterol/total cholesterol ratio (p = 0.01) and a higher high density lipoprotein cholesterol/low density cholesterol ratio (p = 0.02) in the insulin-infused group. The timing of this effect of insulin implies a mechanism unrelated to high density lipoprotein turnover. Thus, insulin infusion during euglycemia appears to alter cholesterol distribution favorably in normal subjects.

Adult↗
PubMedDate not supplied

Absence of lipoprotein lipase in cultured human adipose stromal cells.

To develop a system for studying the regulation of adipose tissue lipoprotein lipase (LPL) in human cells, we isolated cells from the stromalvascular fraction of human adipose tissue and propagated them in tissue culture. These cells were cultured in medium containing fetal bovine, horse, or human sera in the absence or presence of aminoglycoside antibiotics. After the cells had been at confluence for at least 1 week, they were exposed to medium containing insulin, 3-isobutyl-l-methylxanthine (IBMX), and dexamethasone, in an attempt to induce differentiation into cells which produce LPL. Stromal cells in 62 cultures from 20 subjects were monitored for any LPL activity secreted into the culture medium. In addition, cultures were assayed for activity releasable with heparin, and extractable from cell digests in nonionic detergent. Upon reaching confluence, the human adipose tissue stromal cells began to accumulate lipid droplets. However, no consistent LPL activity was measured in the culture medium or after exposure to heparin. Five cultures contained a minimal amount of detergent extractable hydrolytic activity. In contrast, cultures of rat stromal cells not exposed to insulin, IBMX, and dexamethasone, contained assayable LPL in the culture medium (3.3 +/- 1.6 nEq/min/ml) and in the heparin-releasable fraction (1.7 +/- 0.5 nEq/min/10(6)cells). Thus, human adipose tissue stromal cells do not represent a useful system for studying the regulation of LPL. Although these cells accumulate some lipid, the absence of measurable LPL suggests that complete differentiation has not yet occurred.

Adipose Tissue↗
PubMedDate not supplied

Plasma lipids and microangiopathy in insulin-dependent diabetes mellitus.

The relationship of plasma levels of high density lipoprotein (HDL) cholesterol, apolipoproteins A-I and A-II (the major apolipoproteins in HDL), low density lipoprotein (LDL) cholesterol, triglyceride, and glucose to microangiopathy was evaluated in 49 insulin-dependent diabetic subjects. Although the HDL cholesterol/LDL cholesterol ratio (a risk determinant for macroangiopathy) was lower in women with proteinuria, no other relationships between HDL cholesterol or the A apolipoproteins and renal microangiography were found. The only independent association between HDL and retinal microangiopathy was found in women, where an inverse correlation was found between the apo A-I/apo A-II ratio and the number of microaneurysms (rs = -0.561, P less than 0.05). Men showed strong relationships of glucose, triglyceride, cholesterol, and LDL cholesterol to renal microangiopathy whereas women, in general, had stronger correlations of these variables with retinal microangiopathy. Thus, several alterations in lipoprotein cholesterol distribution and HDL composition are associated with diabetic microangiopathy. In addition, differences between sexes suggest that previously undescribed hormonal factors may influence the severity of this process.

Adolescent↗