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Biomedical subjects

B Rifkind

Publications and source records attributed to B Rifkind.

13 recordsLinked to original sources
PubMed1992

Report of the Conference on Low Blood Cholesterol: Mortality Associations.

BACKGROUND: A National Heart, Lung, and Blood Institute (NHLBI) Conference was held October 9-10, 1990, to review and discuss existing data on U-shaped relations found between mortality rates and blood total cholesterol levels (TC) in some but not other studies. Presentations were given from 19 cohort studies from the United States, Europe, Israel, and Japan. A representative of each study presented its findings and also submitted tables of proportional hazards regression coefficients for entry TC levels in regard to death, and these were incorporated into a formal statistical overview adjusted for age, diastolic blood pressure, cigarette smoking, body mass index, and alcohol intake, as available. METHODS AND RESULTS: The U-shape for total mortality in men and the flat relation in women resulted largely from a positive relation of TC with coronary heart disease death and an inverse relation with deaths caused by some cancers (e.g., lung but not colon), respiratory disease, digestive disease, trauma, and residual deaths. Risk for combined noncardiovascular, noncancer causes of death decreased steadily across the range of TC. The conference considered possible explanations for the statistical associations found between low TC levels or active TC lowering and certain causes of death. One is that TC is lowered by some disease conditions themselves, such as wasting in chronic pulmonary disease or reduced production and secretion of cholesterol-bearing lipoproteins with liver disease. In this sort of situation, the TC:mortality association found in observational studies may be due to preexisting disease. This was addressed by excluding early deaths from the analysis, which did not change the results. The conference considered as well the biological function of cholesterol, which, if seriously deranged, might hypothetically cause a wide variety of diseases and dysfunction. The conference also considered the biological functions that might provide plausible mechanisms for the associations found. CONCLUSIONS: Definitive interpretation of the associations observed was not possible, although most participants considered it likely that many of the statistical associations of low or lowered TC level are explainable by confounding in one form or another. The conference focused on the apparent existence and nature of these associations and on the need to understand their source rather than on any pertinence of the findings for public health policy. Further research is recommended to explain the observed associations of low TC levels (and TC lowering) with certain noncardiovascular diseases. This includes studies of the time course of TC change in disease, the relation of TC to morbidity, further studies of possible epidemiological confounding, monitoring of population trends in TC and mortality, further studies of the relations in women, auditing of noncardiovascular events in trials, studies of cell membrane, genetic and molecular links to cholesterol metabolism, TC level and disease, studies of disease manifestations in specific lipid disorders, and further study of the proposed causal mechanisms linking low TC and hemorrhagic stroke.

Alcohol Drinking↗
PubMed1990

Serum lipids and lipoproteins of Hispanics, 1982-84.

This report presents descriptive data for serum lipids and lipoproteins by age, sex, and selected socioeconomic variables. This information is from the Hispanic Health and Nutrition Examination Survey, a sample survey of selected groups of civilian noninstitutionalized Hispanic persons residing in selected area of the United States, that was conducted during the period 1982-84.

Adult↗
PubMed1989

High density lipoprotein cholesterol levels among US adults by selected demographic and socioeconomic variables. The Second National Health and Nutrition Examination Survey 1976-1980.

The distribution of serum high density lipoprotein cholesterol (HDL cholesterol) levels was determined on a nationally representative sample of 9,625 adults aged 20-74 years, as part of the Second National Health and Nutrition Examination Survey, 1976-1980 (NHANES II). Mean HDL cholesterol levels were higher in women compared with men (an age-adjusted difference of 8.9 mg/dl for whites and 4.4 mg/dl for blacks). HDL cholesterol levels were higher in blacks compared with whites (an age-adjusted difference of 7.4 mg/dl for men and 2.8 mg/dl for women). All differences were statistically significant (p less than 0.01). These relations remained after stratification by age, income, poverty index, education, body mass index, alcohol consumption, cigarette smoking, and physical activity. For whites, HDL cholesterol levels were highest in the highest category of earnings, whereas blacks generally had lower levels of HDL cholesterol with increased earnings. In a multivariate model, important predictors of higher HDL cholesterol levels were being female, being black, and reporting a higher frequency of alcohol consumption. Less strongly related were age, years of education, and reported high physical activity. Smoking and body mass index were strongly negatively related to HDL cholesterol levels. The findings in this national study support previous findings in selected populations in the United States.

Adult↗
PubMed1986

Comparison of plasma lipids, lipoproteins and dyslipoproteinemia in Israel and the United States. The Lipid Research Clinics Program Prevalence Study.

Based on the common study design, protocol, and laboratory techniques used by the Lipid Research Clinics (LRCs), the study reported here compared the adult study populations examined by the U.S. LRCs and the LRC located in Jerusalem, Israel. A number of 2388 residents of Jerusalem were contrasted with 6528 examinees of the U.S. LRCs regarding their plasma lipid and lipoprotein cholesterol distributions. Marked differences between the U.S. and Jerusalem LRCs were observed in the plasma levels of lipids and lipoprotein cholesterol fractions. Mean total cholesterol concentrations were 2-8% higher in the U.S. compared to the Jerusalem sample. Low density lipoprotein cholesterol levels were higher by approximately 5-15% in the U.S. LRCs, a phenomenon more marked in men than women and in older compared to younger study participants. High density lipoprotein cholesterol values were also higher in the U.S. compared to the Jerusalem LRC, by approximately 10-14% in men and women. These differences were also more pronounced in older compared to younger participants. By contrast, median plasma total triglycerides (and by implication very low density lipoprotein cholesterol) were higher in the Jerusalem compared to the U.S. study participants. This difference ranged from 10-21% by age and sex. The correlations between the plasma lipid/lipoprotein measurements were similar in the two study populations. Only the degree of linear association between plasma total triglyceride and very low density lipoprotein cholesterol was different between the U.S. and Jerusalem, with a correlation coefficient of greater magnitude in the latter. Employing common cutpoints to define dyslipoproteinemia (DLP) observed differences in plasma lipid/lipoprotein distributions determined differences in the frequency of DLP categories between the U.S. and the Jerusalem samples. Higher proportions of Type IV and hypo-HDL were observed in Jerusalem compared to the U.S. By contrast, fewer individuals were classified as Type IIa, Type IIb, and hyper-HDL in Jerusalem relative to the U.S.

Adult↗
PubMed1983

Effect of estrogen/progestin potency on lipid/lipoprotein cholesterol.

We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women, using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P less than 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Enovid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives.

Adult↗
PubMed1982

Assessment of plasma total cholesterol as a test to detect elevated low density (beta) lipoprotein cholesterol levels (type IIa hyperlipoproteinemia) in young subjects from a population-based sample.

The measurement of plasma total cholesterol as a screening test for an increased plasma level of low density lipoprotein cholesterol (greater than age- and sex-adjusted 95th percentile) with a normal plasma triglyceride level (type IIa hyperlipoproteinemia) was assessed in 1325 young subjects, aged 6 to 19 years, from seven North American populations during the years 1972-1976. When the age- and sex-specific 95th percentile for total cholesterol was used as the cutpoint for hypercholesterolemia, almost one third of young subjects with type IIa hyperlipoproteinemia were undetected (false negatives), and 40% of the test results were falsely positive. Ninety-eight per cent of all non-type IIa subjects were correctly identified. Lowering the percentile cutpoint decreased the false negative results but increased the false positive results; increasing the cutpoint had an opposite effect. Females had higher percentile cholesterol values than males; when extrinsic, arbitrary cholesterol cutpoints (175-210 mg/100 ml) for screening were used, there were fewer false negative but more false positive results in the females than in the males. When the prevalence of type IIa hyperlipoproteinemia was increased from 5 to 50%, the false positive tests decreased from 40 to 2%. A two-step screening for hypercholesterolemia did not improve efficiency. The use of plasma total cholesterol as a test for type IIa hyperlipoproteinemia in a general population results in a relatively large number of false positive and false negative tests.

Adolescent↗
PubMed1980

Plasma cholesterol and triglyceride distributions in 13,665 children and adolescents: the Prevalence Study of the Lipid Research Clinics Program.

The age-, race-, sex-specific distributions for plasma cholesterol (CH) and triglyceride (TG) are described for the 13,655 individuals under 20 years of age who were examined at the first visit (visit I) of the Prevalence Study of the Lipid Research Clinics (LRC) Program. Composite findings are presented from the seven North American LRC's where children were included in the target population. Cholesterol values are higher for blacks than for whites, but triglyceride values are higher for whites than for blacks. In both the CH and TG distributions for the combined races, the mean values for females are generally higher than for males. For cholesterol, consistent age-associated differences occur. On average, the CH values peak in late childhood and decline during adolescence. The decrease in mean values for CH is most marked for white males. The values for TG tend to increase in early adolescence. This report expands the available information about lipid distributions in young populations and describes the extent of the variation in plasma lipids associated with race and sex for each year of age, 0 to 19 years.

Adolescent↗