Skeletal muscle fiber distribution influences serum high-density lipoprotein cholesterol level

Earlier we have shown a significant positive association between muscle fiber distribution, i.e. percentage of slow-twitch (ST) fibers in the vastus lateralis muscle, and serum high-density lipoprotein cholesterol (HDL-C) level. This association may be due to the fact that ST fibers have a high capacity for oxidative energy metabolism and a high number of surrounding capillaries. These fibers have a high capacity to metabolize fatty acids liberated by lipoprotein lipase (LPL) from triglyceride-rich lipoproteins. This in turn elevates serum HDL-C levels. Thus, a high percentage of ST fibers (ST-%) may be one factor having a beneficial effect on serum HDL-C concentration. A high ST-% may also increase the likelihood that a person will become involved in an endurance type of physical activity, which further increases serum HDL-C concentration by increasing further LPL activity in the capillary bed of skeletal muscle. In this paper we present a hypothetical background of the role that ST fibers may have on serum lipid and lipoprotein profile.     

The relationship between hepatic low-density lipoprotein receptor activity and serum cholesterol level in the human fetus

We found that the binding of 125I-low-density lipoprotein to fetal liver low-density lipoprotein receptor rose progressively with the increase in fetal age. During this period, total cholesterol and low-density lipoprotein-cholesterol levels in fetal serum declined significantly. The correlation coefficients between fetal age and concentration of serum total cholesterol and low-density lipoprotein cholesterol were -0.80 (p less than 0.001) and -0.77 (p less than 0.001), respectively. A significant inverse correlation also existed between the liver low-density lipoprotein receptor activity and the serum total cholesterol (r = -0.96, p less than 0.001) and low-density lipoprotein cholesterol (r = -0.95, p less than 0.001) but not high-density lipoprotein cholesterol. It is suggested that the low-density lipoprotein receptors in human fetal liver may play a key role in the regulation of the serum cholesterol levels during gestation.     

Total serum cholesterol and cholesterol lipoprotein fractions in random sample of Warsaw population

The aim of the study was to evaluate the level of lipid risk factors in a random sample of Warsaw population aged 35-64 years, 764 men and 775 women, were screened within framework of the Pol-MONICA Warsaw Study. The lipids were determined by enzymatic methods in laboratory controlled by CDC Lipid Standardization Program in Atlanta. In the screened sample the observed levels of total cholesterol (5.76 +/- 1.01 and 5.68 +/- 1.03 mmol/l respectively in men and in women) and LDL cholesterol (3.67 +/- 0.90 and 3.56 +/- 0.94 mmol/l respectively) were rather high what can indicate on rather high coronary risk of Warsaw population. On the other hand the high mean level of HDL cholesterol (1.36 +/- 0.36 and 1.53 +/- 0.35 mmol/l respectively) and its subfractions HDL2 (0.24 in men and 0.39 mmol/l in women) as well as HDL3 (1.12 and 1.14 mmol/l respectively) observed in this sample can decrease this global risk. The compared mean level of cholesterol in lipoprotein fractions in the group of investigated persons with and without clinical manifestations of coronary heart disease confirm the observed in the other studies the higher mean levels of total cholesterol and LDL cholesterol in persons with coronary heart disease.     

The value of serum albumin and high-density lipoprotein cholesterol in defining mortality risk in older persons with low serum cholesterol

OBJECTIVES: To investigate the relationship between low cholesterol and mortality in older persons to identify, using information collected at a single point in time, subgroups of persons with low and high mortality risk. DESIGN: Prospective cohort study with a median follow-up period of 4.9 years. SETTINGS: East Boston, Massachusetts; New Haven, Connecticut; and Iowa and Washington counties, Iowa. PARTICIPANTS: Four thousand one hundred twenty-eight participants (64% women) age 70 and older at baseline (mean 78.7 years, range 70-103); 393 (9.5%) had low cholesterol, defined as < or =160 mg/dl. MEASUREMENTS: All-cause mortality and mortality not related to coronary heart disease and ischemic stroke. RESULTS: During the follow-up period there were 1,117 deaths. After adjustment for age and gender, persons with low cholesterol had significantly higher mortality than those with normal and high cholesterol. Among subjects with low cholesterol, those with albumin> 38 g/L had a significant risk reduction compared with those with albumin < or =38 g/L (relative risk (RR) = 0.57; 95% confidence interval (CI) = 0.41-0.79). Within the higher albumin group, high-density lipoprotein cholesterol (HDL-C) level further identified two subgroups of subjects with different risks; participants with HDL-C <47 mg/dl had a 32% risk reduction (RR = 0.68; 95% CI = 0.47-0.99) and those with HDL-C > or =47 mg/dl had a 62% risk reduction (RR = 0.38; 95% CI = 0.20-0.68), compared with the reference category; those with albumin < or =38 g/L and HDL-C <47 mg/dl. CONCLUSIONS: Older persons with low cholesterol constitute a heterogeneous group with regard to health characteristics and mortality risk. Serum albumin and HDL-C can be routinely used in older patients with low cholesterol to distinguish three subgroups with different prognoses: (1) high risk (low albumin), (2) intermediate risk (high albumin and low HDL-C), and (3) low risk (high albumin and high HDL-C).