Lewis I. Gidez

Plasma lipids and lipoproteins and the incidence of cardiovascular disease in the very elderly. The Bronx Aging Study.

The Bronx Aging Study is a 10-year prospective investigation of very elderly volunteers (mean age at study entry, 79 years; range, 75-85 years) designed to assess risk factors for dementia and coronary and cerebrovascular (stroke) diseases. Entry criteria included the absence of terminal illness and dementia. All subjects (n = 350) included in this report had at least two lipid and lipoprotein determinations. Overall, more than one third of subjects showed at least a 10% change in lipid and lipoprotein levels between the initial and final measurements. Moreover, mean levels for women were consistently different than those for men, and because of this finding subjects were classified into potential-risk categories based on the changes observed by using their sex-specific lipid and lipoprotein distributions. The incidences of cardiovascular disease, dementia, and death were compared between risk groups. Proportional-hazards analysis showed that in men a consistently low high density lipoprotein cholesterol level (less than or equal to 30 mg/dl) was independently associated with the development of myocardial infarction (p = 0.006), cardiovascular disease (p = 0.002), or death (p = 0.002). For women, however, a consistently elevated low density lipoprotein cholesterol level (greater than or equal to 171 mg/dl) was associated with myocardial infarction (p = 0.032). Thus, low high density lipoprotein cholesterol remains a powerful predictor of coronary heart disease risk for men even into old age, while elevated low density lipoprotein cholesterol continues to play a role in the development of myocardial infarction in women. The findings suggest that an unfavorable lipoprotein profile increases the risk of cardiovascular morbidity and mortality even at advanced ages for both men and women.

Extrahepatic synthesis of lipoproteins of plasma and chyle: role of the intestine.

Several groups of investigators (1-3) have shown that the protein portion of the plasma lipo-proteins of the rat can be synthesized by the liver. The present studies were undertaken to determine whether any lipoprotein synthesis can occur in the absence of the liver. Previous work by Bragdon (4) and by Rodbell, Fredrickson, and Ono (5) has suggested intestinal synthesis of lipoproteins. Since their studies were carried out in intact animals, however, the liver could not be excluded as a source of these proteins. We have therefore measured the synthesis of the protein component of the lipoproteins of chyle and plasma in hepatectomized dogs. Methods Male mongrel dogs weighing 12 to 18.5 kg were fasted for 18 hours before operation. The dogs were anesthe-tized with pentobarbital (35 mg per kg iv). The following types of preparations were used: a) hepatecto-mized dogs, b) hepatectomized dogs with thoracic duct fistulas, c) eviscerated dogs, and d) an anesthetized normal control.

The Clinical Significance of the Plasma High Density Lipoproteins

The consistent body of evidence supporting a relationship between high density lipoproteins and coronary heart disease is examined. However, an actual causal relationship has yet to be demonstrated. Methods of measuring HDL are presented and the difficulties with clinical measurement and evaluation are explored.

High-density lipoprotein subclasses in diabetes

This cross-sectional study evaluated high-density lipoprotein subclasses measured by a precipitation technique before and after treatment in men and women with types I and II diabetes. Total high-density lipoprotein cholesterol was lower in subjects of both sexes with untreated type I and type II diabetes, the change occurring primarily in subclass 2. Insulin therapy raised total and subclass 2 high-density lipoprotein levels in men and women with type I and type II diabetes, the predominant rise occurring in subclass 2. The improvement was unrelated to metabolic control. Normalization of total and subclass 2 high-density lipoprotein was not achieved in women with type II disease who had higher body weights and triglyceride levels. Treatment with oral hypoglycemic agents did not lower total high-density lipoprotein or subclass 2 levels. It is concluded that therapies affecting high-density lipoprotein produce the preponderant change in subclass 2, insulin therapy increases total and subclass 2 high-density lipoprotein but may not restore levels to normal in the presence of elevated body weight and lipid levels, there is no relation between control of diabetes and changes in total and subclass 2 high-density lipoprotein levels, and treatment with oral hypoglycemic agents does not adversely affect high-density lipoprotein levels.

Serum lipids and lipoproteins in advanced age. Intraindividual changes.

The Bronx Aging Study is a longitudinal investigation of nondemented, nonterminally ill, community-residing, old old volunteer subjects, designed to assess risk factors for the development of dementia and coronary and cerebrovascular diseases. During the first five annual evaluations, total cholesterol, high-density (HDL) and low-density lipoprotein (LDL), and triglyceride levels were measured. Mean cholesterol values (+/- standard error of the mean) for subjects at baseline were significantly higher for women than for men. Respectively, the values for total cholesterol were 6.1 +/- .1 mm/L (234 +/- 3 mg/dL) and 5.3 +/- .1 mm/L (207 +/- 3 mg/dL); for LDL cholesterol, 4.1 +/- .1 mm/L (158 +/- 2 mg/dL) and 3.7 +/- .1 mm/L (141 +/- 3 mg/dl); and for HDL cholesterol, 1.2 +/- .1 mm/L (47 +/- 1 mg/dL) and 1.0 +/- .1 mm/L (38 +/- 1 mg/dL). Mean triglyceride levels were 1.5 +/- .1 mm/L (135 +/- 5 mg/dL) for women and 1.6 +/- .1 mm/L (138 +/- 5 mg/dL) for men. Further, mean values remained stable over time. However, there was considerable intraindividual change observed in a substantial proportion of subjects between initial and final determinations. Changes of at least 10% from baseline were observed in 41%, 63%, 52%, and 78% of the cohort for cholesterol, HDL, LDL, and triglycerides, respectively. Thus, single measurements appear inadequate for establishing a diagnosis of hyperlipidemia in the elderly.

Response of rat zona glomerulosa in experimental nephrosis.

Summary In rats rendered nephrotic by repeated injections of the aminonucleoside of Puromycin, the adrenocortical glomerulosa became hypertrophied. Greatest enlargement occurred on 15th day of experiment, prior to maximal accumulation of ascitic fluid in other animals in the group. Diuresis in surviving animals occurred after glomerulosa had begun to shrink. Figure