Bruce A. Kottke

Apolipoprotein A-I as a Marker of Angiographically Assessed Coronary-Artery Disease

This study was designed to determine whether the plasma level of apolipoprotein A-I is a better discriminator of angiographically documented coronary-artery disease than the level of high-density-lipoprotein (HDL) cholesterol in male subjects. The level of plasma apolipoprotein A-I in 83 patients with coronary-artery disease was 96.7 +/- 4.2 mg per deciliter (mean +/- S.E.M.), which was significantly lower (P less than 0.0001) than the level in 25 patients without coronary-artery disease (146.9 +/- 2.1 mg per deciliter). The levels of HDL cholesterol were also lower (P less than 0.0001) in patients with coronary-artery disease (31.9 +/- 1.5 mg per deciliter) than in those without it (45.9 +/- 2.3 mg per deciliter). A stepwise discriminant analysis, however, indicated the superiority of apolipoprotein A-I over HDL cholesterol in detecting coronary-artery disease. Furthermore, a linear discriminant analysis suggested that although HDL cholesterol by itself was a discriminator of coronary-artery disease, it did not provide a substantial increase in discriminatory value over that provided by apolipoprotein A-I; in contrast, apolipoprotein A-I levels added discriminatory value to the information obtained by measuring HDL cholesterol alone. We conclude that apolipoprotein A-I by itself is more useful than HDL cholesterol for identifying patients with coronary-artery disease.

Pathologic changes in aortocoronary saphenous vein grafts

Abstract Aortocoronary saphenous vein grafts from 40 patients (total 62 grafts) were studied at autopsy. The earliest change seen was the insudation of blood constituents into the vein intima. Occluding thrombi were seen in six grafts from short-term survivors, and one organized thrombus was seen in a graft from a long-term survivor (28 months). Various degrees of intimai thickening were seen in grafts from all patients surviving for more than a month; this had progressed to diffuse occlusion in three cases. Gross and microscopic findings correlated well with postmortem angiographic findings in the long-term survivors. Electron microscopic examination showed smooth muscle cells, collagen fibers and ground substance in the thickened intima. Fibroblasts were not a feature of this thickening. Increased permeability of the graft endothelium, due to injury or hemodynamic factors, may result in exposure of medial smooth muscle cells to certain plasma factors and thus promote smooth muscle cell hyperplasia as has been produced in certain experimental models.

Apolipoproteins and coronary artery disease

In this study, we compared the relative utility of plasma levels of cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and apolipoproteins in identifying men with angiographically significant coronary artery disease in a combined sample of consecutive male patients undergoing coronary angiography (N = 304) and healthy, normal male control subjects (N = 135). The plasma apolipoprotein levels were measured by using specific radioimmunoassays. We found that plasma levels of apolipoprotein A-I, followed by those of apolipoproteins A-II and B, were better discriminators than plasma cholesterol, triglycerides, or HDL cholesterol levels for identifying those with coronary artery disease. In confirmation of previous findings, the presence of coronary artery disease resulted in lower levels of apolipoproteins A-I and A-II and HDL cholesterol and higher levels of apolipoprotein B, cholesterol, and triglycerides. Linear and quadratic discriminant function analysis demonstrated that by using the age of the patients and apolipoprotein A-I, A-II, and B levels, one could correctly classify patients either as being normal or as having angiographically significant coronary artery disease in more than 75% of the cases. Thus, plasma apolipoprotein levels (especially A-I and A-II) may be considerably better markers for coronary artery disease than traditional lipid determinations.

Analysis of plasma lipids and apolipoproteins in insulin-dependent and noninsulin-dependent diabetics

Plasma triglycerides, cholesterol, high-density lipoprotein (HDL) cholesterol, and apolipoproteins (apo) A-I, A-II, C-II, and C-III were determined and analyzed in 170 diabetic patients and 46 age-matched healthy normal subjects. The diabetics were separated into two groups: insulin-dependent diabetes mellitus (IDDM, n = 78) and noninsulin-dependent diabetes mellitus (NIDDM, n = 92). Significantly increased triglycerides, low HDL cholesterol, and normal cholesterol levels were found in the diabetics. The lipid profiles were similar in the IDDM and NIDDM groups. Plasma apo A-I, but not apo A-II, was low in both groups of diabetics. However, only in the IDDM subjects was there a statistically significant decrease in apo A-I when compared to normal subjects. The decreased apo A-I level negatively correlated with plasma triglycerides. Apo C-II and apo C-III were slightly increased in the diabetics compared to normal subjects. Apo C-II and apo C-III levels significantly correlated with plasma triglycerides (apo C-II, r = 0.70, P less than 0.0001; apo C-III, r = 0.71, P less than 0.0001). Only apo C-II correlated with total cholesterol. Thirty-eight to forty-two percent of the IDDM and NIDDM subjects had a clinical diagnosis of coronary artery disease (CAD) and/or peripheral arteriovascular disease (PAD). In the IDDM subjects, but not in the NIDDM subjects the incidence of CAD and/or PAD was associated with the decreased apo A-I levels as evaluated by a univariate analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of risk factor variables and coronary artery disease documented with angiography.

Stepwise linear discrimination was used to analyze risk factors in 431 consecutive patients who underwent coronary angiography to determine which variables were most closely associated with coronary artery disease. Twenty-one risk factors were considered: total plasma cholesterol and triglycerides; the cholesterol and triglyceride content of high-density lipoproteins (HDL), low-density lipoproteins (LDL) and very low density lipoproteins (VLDL); and the percentage of total cholesterol and triglycerides in each fraction. Age, smoking history, family history, hypertension, diabetes mellitus and relative weight were also considered. Coronary artery disease was assessed using three standard grading scores. There were significant differences in risk factors between males and females. In males, LDL cholesterol and age were selected by multivariate analysis. In females, the ratio of HDL cholesterol to total cholesterol, as well as relative weight, family history, age and smoking were selected. The discriminating value of HDL cholesterol as the percentage of total cholesterol was significantly greater than that of HDL cholesterol itself. Despite highly significant associations between risk factors and the presence of coronary artery disease, the discrimination did not provide sufficient separation of the groups to give results that are useful diagnostically in individual patients.

Total cholesterol and lipoproteins in school children: prediction of coronary heart disease in adult relatives.

The distribution of risk factors and the prevalence of coronary heart disease (CHD) were studied in 850 first- and second-degree relatives of 98 healthy index cases selected from 3666 school children surveyed for lipid levels in Rochester, Minnesota. Three groups of families were based on an index childs total plasma cholesterol level: 18 families with a child in less than the fifth percentile (low-cholesterol group), 47 with a child in the fifth to ninety-fifth percentiles (middle-cholesterol group) and 33 with a child in greater than the ninety-fifth percentile (high-cholesterol group). The childrens cholesterol levels clustered with those of their relatives; mortality due to CHD before age 65 was increased by 2.5 times in grandfathers of index cases in the high-cholesterol group compared with those of the middle-cholesterol group (p < 0.016). The prevalence of CHD in all the grandfathers was associated with an index childs total cholesterol, more strongly associated with an index childs low-density lipoprotein cholesterol level and most strongly associated with an index childs high-density lipoprotein cholesterol level as a fraction of total cholesterol. This study establishes that childhood lipid and lipoprotein levels from a single cross-sectional survey identify families at elevated risk for CHD.

Levels of Lipids, Lipoproteins, and Apolipoproteins in a Defined Population

As part of a large cross-sectional investigation--the Rochester Family Heart Study--plasma levels of lipids, lipoproteins, and apolipoproteins were measured in a sample from the general population of male and female subjects who ranged in age from 5 to 90 years. Polyclonal radioimmunoassays developed at the Mayo Clinic were used for measurement of apolipoproteins A-I, A-II, C-II, C-III, and E, whereas a monoclonal enzyme-linked immunosorbent assay was used for apolipoprotein B. On the basis of 984 subjects who reported that they were fasting, were not pregnant, had never smoked, and were taking no medications thought to influence lipid levels, we determined age- and gender-specific percentiles for plasma levels of cholesterol, triglycerides, high-density lipoprotein cholesterol, and six apolipoproteins. These percentiles will facilitate identification of persons who are in the highest and lowest percentiles for their age and gender. The levels of the apolipoproteins varied for both age and gender. This is the first study to provide a reference sample for plasma levels of these apolipoproteins for male and female subjects 5 to 90 years of age selected from the general population.

Niacin-Induced Hepatitis: A Potential Side Effect With Low-Dose Time-Release Niacin

Hepatitis developed in five patients who were taking low dosages (3 g/day or less) of time-release niacin. In four of the five patients, clinical symptoms of hepatitis developed after the medication had been taken for a relatively short time (2 days to 7 weeks). This manifestation of hepatotoxicity seems to differ from that previously reported in association with use of crystalline niacin, which occurred with high dosage and prolonged usage of the medication. In view of the recent increased frequency of prescribing niacin for the treatment of hyperlipidemia, physicians should be aware of the potential for hepatotoxicity with even low-dose and short-term use of time-release niacin.

Increase in Total Plasma Homocysteine Concentration After Cardiac Transplantation

OBJECTIVE To determine whether plasma homocysteine concentrations are increased in patients after cardiac transplantation. DESIGN Total plasma homocysteine concentration was measured in 44 consecutive patients before and at 3, 6, and 12 months after orthotopic heart transplantation between June 1, 1988, and Oct. 15, 1992, and the data were analyzed statistically. RESULTS Mean homocysteine concentrations (normal range, 4 to 17 mumol/L) increased 70% from 12.5 mumol/L before cardiac transplantation to 21.2 mumol/L (P < 0.002) 3 months after transplantation, at which time the concentrations were above normal in 14 of 26 patients (54%). Homocysteine concentrations remained elevated 6 and 12 months after transplantation (20.4 and 22.6 mumol/L, respectively) but did not increase further. Mean concentrations of plasma folic acid and vitamin B12, cofactors in homocysteine metabolism, decreased 20% and 49%, respectively, within 3 months after transplantation (11.6 to 9.3 micrograms/L [P = 0.04] and 584 to 295 ng/L [P = 0.01]). The mean glomerular filtration rate decreased 25% during this same interval (81 to 61 mL/min; P = 0.0001). Linear regression analysis revealed an association between the increase in homocysteine concentration and the folic acid concentration that approached statistical significance (P = 0.07); we found no statistically significant correlates of the increase in homocysteine concentration. CONCLUSION The homocysteine concentration increases in most patients within 3 months after cardiac transplantation to levels previously associated with premature atherosclerotic coronary artery disease, and it remains increased for at least 1 year. Further investigation into the mechanism for the increase in homocysteine concentration and the relationship between homocysteine and coronary artery disease after transplantation is warranted.

Insulinemia in Children at Low and High Risk of NIDDM

OBJECTIVE Fasting hyperinsulinemia in the presence of normoglycemia usually indicates insulin resistance and is characteristic of populations at high risk for developing NIDDM. Hyperinsulinemia predicts the development of impaired glucose tolerance and NIDDM in Pima Indians, a population with a high incidence of NIDDM. Insulin concentrations in population-based samples of children who have different risks of developing NIDDM later in life have not been reported previously. RESEARCH DESIGN AND METHODS We compared fasting insulin concentrations in two populations of nondiabetic children, 6–19 yr of age: Pima Indians from southern Arizona and Caucasians from Minnesota. RESULTS Insulin concentration varied with age, sex, glucose concentration, and relative weight. Mean fasting insulin concentration was 140.3 pM in Pima Indian males, 94.4 pM in Caucasian males, 171.5 pM in Pima Indian females, and 107.1 pM in Caucasian females. For each sex, the mean fasting insulin concentration, controlled for age, glucose, and relative weight, was significantly higher in the Pima Indians than in the Caucasians (P < 0.001). CONCLUSIONS From a young age, Pima Indian children have higher fasting insulin concentrations than Caucasian children. As hyperinsulinemia predicts subsequent NIDDM, these data suggest that the susceptibility to NIDDM is manifest at a young age as fasting hyperinsulinemia.