Cultures of human diploid fibroblasts were shown to accumulate elevated levels of intracellular triglyceride when grown in medium supplemented with sera from patients with endogenous hypertriglyceridemia (Type IV hyperlipoproteinemia). Time course studies indicated cell triglyceride levels reached maxium in 6 to 12 hours. Isotopic studies indicated that the source of the accumulated cell triglyceride was serum triglyceride, and that most of the triglyceride was taken up without hydrolysis. Triglyceride was not significantly removed by trypsinization or extensive washing. The accumulated triglyceride was also demonostrated to be metabolized, as indicated by conversion to phospholipids and free fatty acids. Increasing concentrations of hypertriglyceridemic serum in the medium resulted in increasing cell triglyceride levels. However, increasing amounts of normal serum did not result in comparable cell triglyceride accumulation. Intracellular triglyceride accumulation seemed to correlate with levels of hypertriglyceridemic serum triglyceride, whether this serum was present at equivalent concentrations or normalized to triglyceride levels equivalent to normal serum. It is concluded that elevated serum triglyceride levels can result in intracellular triglyceride accumulation even in the absence of lipolytic activity.

Cell Membrane Permeability↗

PubMedDate not supplied

Plasma and lipoprotein cholesterol and triglyceride in the Pima Indian population. Comparison of diabetics and nondiabetics.

Lipoprotein cholesterol and triglyceride concentrations were compared in diabetic and nondiabetic Pima Indians, a homogeneous population with a high occurrence of noninsulin-dependent diabetes mellitus. Data were available on 690 subjects with diabetes or impaired glucose tolerance. Total and very low density lipoprotein (VLDL) triglycerides were approximately 150% of the nondiabetic values, but very few diabetics had pronounced hypertriglyceridemia. Significant elevations in low density lipoprotein (LDL) triglyceride were also observed in diabetic men and women of all ages. Decreases in high density lipoprotein (HDL) cholesterol were similar in diabetic men and women, and the differences in HDL cholesterol were much greater in less obese individuals. Changes in HDL in the diabetics were reflected in all three subfractions, HDL2b, HDL2a, and HDL3. Both total and LDL cholesterol were elevated in diabetic women, but not in diabetic men. Thus, there were greater changes in lipoprotein distribution in diabetic women. When multiple regression analysis was performed to examine the relationships in diabetics between lipoproteins and other variables, plasma glucose appeared to be the variable most closely associated with plasma lipoproteins in diabetics (positive with VLDL and LDL, negative with HDL). In diabetics, obesity was correlated with HDL but not VLDL, whereas alcohol consumption appeared to be associated with VLDL but not HDL.

Adolescent↗

PubMedDate not supplied

Lack of sex differences in high density lipoproteins in Pima Indians. Studies of obesity, lipase activities, and steroid hormones.

To investigate the reasons for the lack of sex differences in high density lipoproteins (HDL) observed in population studies of the Pima Indians, we selected 18 lean (9 men, 9 women, body mass index (BMI) less than 27) and 22 obese (12 men, 10 women, BMI greater than 27) Pima Indians for an inpatient study of HDL composition. We measured lipase activities and steroid hormone concentrations, both of which have previously been implicated in the control of HDL. The lean women had higher concentrations of HDL and HDL2 than did either the obese women or the lean or obese men. Lean women had significantly lower hepatic lipase activities and significantly higher concentrations of estradiol compared to obese women. Lean women also had different HDL2 composition, as indicated by the molar ratio of HDL2 cholesterol/A-I. Significant negative correlations between HDL and obesity measured by either BMI or percent body fat were observed in both sexes, but the slope of the relationship was steeper in women. Significant negative associations were observed between HDL or HDL2 concentrations and hepatic lipase in both sexes, and there were significant positive associations between HDL2 and plasma estradiol in women. The data suggest that obesity in this population has a stronger negative influence on HDL concentrations in women, possibly through changes in estradiol and hepatic lipase activities. Since there are so few lean women in the Pima population, the net result is that HDL levels in women in the population as a whole do not differ from those of men.

Adult↗

PubMedDate not supplied

Assessment of QT interval and QT dispersion for prediction of all-cause and cardiovascular mortality in American Indians: The Strong Heart Study.

BACKGROUND: Both a prolonged QT interval and increased QT interval dispersion (QTD) have been proposed as surface ECG markers of vulnerability to ventricular arrhythmias and potential predictors of mortality. METHODS AND RESULTS: The predictive values of QT prolongation and QTD were assessed in 1839 participants in the Strong Heart Study, a prospective study of cardiovascular disease in American Indians. ECGs were acquired at 250 Hz; QT intervals were measured by computer in all 12 leads and corrected for heart rate (QTc) by use of Bazett's formula. QTD was calculated as the difference between the maximum and minimum QTc. After a mean follow-up of 3.7+/-0.9 years, there were 188 deaths from all causes, including 55 cardiovascular deaths. In univariate Cox analyses, prolonged QTc and increased QTD were significant predictors of all-cause mortality (chi(2)=53.0, P<0.0001; chi(2)=11.3, P=0.0008) and cardiovascular mortality (chi(2)=14.7, P=0.0001; chi(2)=26.5, P<0.0001). In multivariate Cox regression analyses controlling for risk factors, QTc remained a strong predictor of all-cause mortality (chi(2)=16.5, P<0.0001) and a weaker predictor of cardiovascular mortality (chi(2)=5.8, P=0.016); QTD remained a significant predictor of cardiovascular mortality only (chi(2)=12.5, P=0.0004). CONCLUSIONS: These findings support the value of computerized measurements of QTc and QTD in noninvasive risk stratification and suggest that these surface ECG variables may reflect different underlying abnormalities of ventricular repolarization.

Aged↗

PubMedDate not supplied

Diabetes and atherosclerosis in the Pima Indians.

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Adult↗