Computationally estimated apolipoproteins B and A1 in predicting cardiovascular risk.

OBJECTIVE: Apolipoproteins B (apoB) and A1 (apoA1) may be better markers of atherosclerosis than serum lipids. We used computational methods to estimate apoB and apoA1 from serum total cholesterol, HDL-cholesterol and triglycerides and tested their clinical value in comparison to measured apoB and apoA1 values. METHODS: ApoB and apoA1 were measured with standard methods and estimated based on neural network regression models in 2166 young adult with data on carotid artery intima-media thickness (cIMT). RESULTS: Correlations between estimated and measured apoB and apoA1 were r = 0.98 and r = 0.95, respectively. ApoB/apoA1-ratio (both measured and estimated) associated with cIMT in multivariable models, and predicted cIMT at all levels of LDL-cholesterol concentration. Strong correlations between the estimated apolipoproteins and those measured from fasting samples were replicated in over 15,000 Caucasian subjects (r = 0.93-0.96 for apoB and r = 0.91-0.92 for apoA1). Correlations with cIMT were replicated in over 2000 individuals. Estimated apoB/apoA1-ratio calculated from non-fasting lipids in over 20,000 individuals in the INTERHEART study was better than any of the cholesterol measures for estimation of the myocardial risk. CONCLUSIONS: Serum cholesterol, HDL-cholesterol and triglycerides can be used to compute clinically useful estimates of apoB and apoA1. Using this methodology, estimates of apolipoproteins could be routinely added to laboratory reports to complement lipoprotein lipids in risk assessment.

Associations of maximal strength and muscular endurance test scores with cardiorespiratory fitness and body composition.

The purpose of the present study was to assess the relationships between maximal strength and muscular endurance test scores additionally to previously widely studied measures of body composition and maximal aerobic capacity. 846 young men (25.5 ± 5.0 yrs) participated in the study. Maximal strength was measured using isometric bench press, leg extension and grip strength. Muscular endurance tests consisted of push-ups, sit-ups and repeated squats. An indirect graded cycle ergometer test was used to estimate maximal aerobic capacity (V(O2)max). Body composition was determined with bioelectrical impedance. Moreover, waist circumference (WC) and height were measured and body mass index (BMI) calculated. Maximal bench press was positively correlated with push-ups (r = 0.61, p < 0.001), grip strength (r = 0.34, p < 0.001) and sit-ups (r = 0.37, p < 0.001) while maximal leg extension force revealed only a weak positive correlation with repeated squats (r = 0.23, p < 0.001). However, moderate correlation between repeated squats and V(O2)max was found (r = 0.55, p < 0.001) In addition, BM and body fat correlated negatively with muscular endurance (r = -0.25 - -0.47, p < 0.001), while FFM and maximal isometric strength correlated positively (r = 0.36-0.44, p < 0.001). In conclusion, muscular endurance test scores were related to maximal aerobic capacity and body fat content, while fat free mass was associated with maximal strength test scores and thus is a major determinant for maximal strength. A contributive role of maximal strength to muscular endurance tests could be identified for the upper, but not the lower extremities. These findings suggest that push-up test is not only indicative of body fat content and maximal aerobic capacity but also maximal strength of upper body, whereas repeated squat test is mainly indicative of body fat content and maximal aerobic capacity, but not maximal strength of lower extremities.

Estimation of VLDL, IDL, LDL, HDL2, apoA-I, and apoB from the Friedewald inputs--apoB and IDL, but not LDL, are associated with mortality in type 1 diabetes.

BACKGROUND: There is an unmet need for a straightforward and cost-effective assessment of multiple lipoprotein risk factors for vascular diseases. AIMS: 1) To study the relation of various lipoprotein lipid and apolipoprotein (apo) measures on the Friedewald inputs, i.e. plasma triglycerides (TG), cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C). 2) To build up regression models for the appropriate measures based solely on the Friedewald inputs. METHODS: Data were available for 1,775 plasma samples, from which very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and HDL were also isolated by ultracentrifugation. For HDL(2)-C and apolipoproteins, 343 and 247 samples were available, respectively. RESULTS: Accurate models were obtained for VLDL-TG (cross-validation r=0.98), LDL-C (r=0.91), HDL(2)-C (r=0.92), apoA-I (r=0.92), and apoB (r=0.95). A semi-quantitative model was obtained for IDL-C (r=0.78). Due to the anticipated role of IDL-C in atherosclerosis, it was still kept within the accepted models and pursued further. The associations of the estimates with premature deaths were studied in 4,084 patients with type 1 diabetes. The associations of IDL-C and LDL-C were markedly different, the best predictors of mortality being apoB, apoB to apoA-I ratio, and IDL-C. CONCLUSIONS: The new models allow identification of clinically relevant lipoprotein profiles with no added cost to the conventional Friedewald formula.