Search PubMed⌕ Search

Biomedical subjects

R R Williams

Publications and source records attributed to R R Williams.

At least 127 records · Page 7Linked to original sources
PubMed1990

Multigenic human hypertension: evidence for subtypes and hope for haplotypes.

Hypertension that occurs before the age of 60 years is strongly aggregated in families, mostly due to genetic factors with weaker contributions from a shared family environment. Hypertension is probably a heterogeneous collection of overlapping subsets of pathophysiological mechanisms, such as dyslipidemia, obesity, hyperinsulinemia and cation metabolism. Highly heritable traits such as sodium-lithium countertransport, urinary kallikrein excretion and a body fat pattern index show evidence of major gene segregation in families with hypertension. They are thought to be intermediate phenotypes in the chain of pathophysiological events leading from specific genes to the distant phenotype of hypertension. They provide evidence of measurable contributions from single gene traits to the susceptibility to hypertension. Genetic linkage studies have suggested that other specific loci (e.g. histocompatibility leukocyte antigen, blood group MN and the haptoglobin protein) contribute to the susceptibility to hypertension. DNA sequencing has shown a point mutation for lipoprotein lipase that conveys susceptibility to lipid abnormalities, and possibly also hypertension, as seen in families with dyslipidemic hypertension. Further application of these approaches, especially in families that include multiple siblings with hypertension, shows promise of a true understanding of how the combined effects of a few specific genes, the polygenic background and selected environmental factors can lead to essential hypertension. This understanding should foster better tailored and more effective approaches to the prevention, diagnosis and treatment of hypertension.

Blood Pressure↗
PubMed1990

Concordant dyslipidemia, hypertension and early coronary disease in Utah families.

A detailed family history questionnaire collected from families of 35,000 sixteen year old high school students in Utah was used to identify population-bases sibships with two or more living adults affected with hypertension under age 60 or coronary artery disease before age 55. Detailed clinical and biochemical evaluations performed during a four-hour visit to a research clinic provided data to test for concordant abnormalities in siblings with either early hypertension or early coronary heart disease. A new syndrome, familial dyslipidemic hypertension (FDH), was found in 48% of the hypertensive sibships. In these FDH subjects, 68% had HDL-cholesterol below the 10th percentile, 49% had triglyceride level above the 90th percentile, and 27% had LDL levels above the 90th percentile. When compared to normolipidemic hypertensive subjects, persons with FDH had significantly elevated fasting plasma insulin levels, increased subscapular skinfold thickness, increased knee width and wrist circumference, and increased levels of VLDL cholesterol and apolipoprotein B. In coronary sibships, concordant abnormalities for lipids were consistent with familial combined hyperlipidemia in 30-40% of sibships, FDH in 15-45% of sibships, and low HDL-C (with normal cholesterol) in 10%. Concordant normal lipids were found in only 15% of sibships. These data suggest that inherited metabolic abnormalities likely explain some co-aggregation of hyperinsulinemia, obesity, hypertension, and early coronary heart disease. Current knowledge also suggests these metabolic abnormalities could be treated or prevented with appropriate modification in lifestyle factors such as diet and exercise as well as through the use of prescription medications.

Adolescent↗
PubMed1990

Population-based frequency of dyslipidemia syndromes in coronary-prone families in Utah.

The frequency of familial dyslipidemia syndromes was determined from blood tests in 33 objectively ascertained families with early coronary heart disease (CHD) (two or more siblings with CHD by the age of 55 years). Three fourths of persons with early CHD in these families had 90th percentile lipid abnormalities (cholesterol level at or above the 90th percentile, triglyceride level at or above the 90th percentile, and/or high-density lipoprotein cholesterol (HDL-C) level at or less than the 10th percentile). The HDL-C and triglyceride abnormalities were twice as common as low-density lipoprotein-cholesterol abnormalities. The most common syndromes found were familial combined hyperlipidemia (36% to 48% of families with CHD), familial dyslipidemic hypertension (21% to 54% of families with CHD), and isolated low levels of HDL-C (15%), with overlapping familial dyslipidemic hypertension with familial combined hyperlipidemia and low-level HDL-C. Well-defined monogenic syndromes were uncommon: familial hypercholesterolemia being 3% and familial type III hyperlipidemia, 3%. Another 15% of families with CHD had no lipid abnormalities at the 90th percentile. Physicians should learn to recognize and treat these common familial syndromes before the onset of CHD by evaluating family history and all three standard blood lipid determinations. Failure to recognize and treat them leaves affected family members at high risk of premature CHD.

Cholesterol, HDL↗
PubMed1989

Recessive inheritance of a high number of sodium pump sites.

The number of sodium pump sites on erythrocytes was measured on 1,847 individuals in 80 Utah kindreds ascertained through probands with cardiovascular disease. Likelihood analysis supported recessive inheritance of high pump number. The major locus explained 14.0% of the variance in pump number; polygenic inheritance explained another 63.4%. Homozygotes for the recessive allele occurred with a frequency of 1.74% and had a mean pump number estimated as 566.0 sites/red blood cell (RBC) versus a mean of 312.2 sites/RBC for the other genotypes. Young individuals with the high pump number genotype were leaner, and older adults with the high pump number genotype were heavier. Diabetes and early hypertension were more prevalent in women with the high pump number genotype. Although not significant, obesity in adults of both sexes and early coronary heart disease in men were more prevalent in individuals with the high pump number genotype.

Body Weight↗
PubMed1989

Cross-spouse correlates of blood pressure in hypertension-prone families in Utah.

This study used a subsample of 543 married couples from a large group of families in Utah, who were originally studied to assess the genetic and environmental determinants of hypertension. Excluding individuals on medication and controlling for the major risk factors for hypertension, evidence was obtained for cross-spouse blood pressure associations equal in magnitude to self-psychosocial and demographic measures. Observed spouse-spouse similarity for blood pressures remained significant after adjustment for shared psychological factors. It is speculated that different aspects of each spouse's nonmarital environments (e.g. work, social support) have differential impacts on the marital environment and on physiologic indicators of health.

Adult↗
PubMed1989

Validity of cigarette smoking habits in three epidemiologic studies in Utah.

Utah has lower incidence and mortality for many smoking-related forms of cancer and heart disease. It is an important epidemiologic question to assess whether the population attributable risk associated with cigarette smoking in this low-risk population is biased from under-reporting because of societal pressures not to smoke. To answer this question, we compared reported cigarette use to serum cotinine values in three different epidemiologic study designs. Included in these analyses were data from men interviewed for a cross-sectional study of dietary intake and hormones, women interviewed as a part of a case-control study of cervical cancer, and men interviewed in conjunction with a cardiovascular disease and hypertension family follow-up study. Cross-sectional study participants reported accurate cigarette usage 93.8% of the time; case-control participants accurately reported cigarette use 98.5% of the time; participants interviewed in the family cohort study correctly reported usage 82.8% of the time. Most inaccurate reporting of smoking was by exsmokers being followed for a disease known to be linked to smoking. The low attributable risk of smoking related to diseases in Utah is not from underreporting of cigarette smoking, and makes Utah an ideal population to examine other risk factors for diseases where smoking increases risk.

Adolescent↗
PubMed1989

Predictive value of a short dietary questionnaire for changes in serum lipids in high-risk Utah families.

Dietary questionnaires and serum cholesterol, triglycerides, and high-density lipoprotein (HDL) cholesterol determinations were completed for 1239 subjects aged greater than or equal to 20 at each of two separate screenings. The mean time between screenings was 2.5 y. After correcting for potential confounding variables, reduction of a measure of dietary cholesterol and saturated fatty acids assessed by two simple questions was a significant independent predictor of reduction in total cholesterol in serum (p less than 0.005). Initial body mass index (BMI) and change in BMI were highly significant predictors of initial values and changes in total cholesterol, triglycerides, and HDL cholesterol in serum. Reduction of dietary saturated fatty acid and cholesterol was significantly correlated with initial serum cholesterol levels, which suggest that serum cholesterol screening may be an important motivating factor for dietary change. Important public health and research implications of these findings are discussed.

Adult↗
PubMed1989

Genetic heritability and common environmental components of resting and stressed blood pressures, lipids, and body mass index in Utah pedigrees and twins.

The relative contributions of genes and shared environment to cardiovascular risk factors were studied in twins and pedigrees in 1983-1985. Sitting, standing, isometric hand grip, bicycling, and mentally stressed (serial subtraction) blood pressures were obtained from 146 male monozygous twins, 162 male dizygous twins, and 1,102 healthy adults in 67 Utah pedigrees. Fasting total plasma cholesterol, triglycerides, high density lipoprotein cholesterol (HDL), and body mass index were also measured. Heritability was estimated before and after adjusting for 12 environmental variables (measures of socioeconomic status; personality types; exercise levels; use of tobacco, alcohol, coffee, etc.) by using age-adjusted twin intraclass correlations. These heritabilities were compared with those obtained from a variance components analysis of the pedigree data separating genetic and common household effects. Sitting and standing blood pressure heritability estimates were much higher from twin than from pedigree data (39-63% in twins vs. 16-22% in pedigrees), as were those for cholesterol and triglycerides (65 and 75% from twins vs. 42 and 37% from pedigrees) and body mass index (51 vs. 21%). Estimates were similar for heritability of HDL cholesterol (51 vs. 45%). Most of the stressed blood pressure heritabilities were similar to sitting blood pressure estimates. No common household effect (except for adjusted HDL cholesterol (24%), p less than 0.01) was statistically significant for the lipids, blood pressures, or body mass index. Environmental variables correlated much better in monozygous twins and spouses than in dizygous twins, brothers, or sisters. Spouse correlations for lipids, blood pressures, and body mass index were low, with a maximum of 0.12 (p less than 0.05) for HDL cholesterol. We conclude that genes contribute much more than shared environment to the well-recognized familial correlation of blood pressures, lipids, and body mass index.

Adult↗
PubMed1989

Current knowledge regarding the genetics of human hypertension.

Observations over 11 years from the University of Utah Cardiovascular Genetics Research Clinic and published data from other studies are reviewed to illustrate research approaches, developing results and prospects for future studies. Strong associations with hypertension have been found for several biochemical tests that show substantial genetic determination. Suggestions of recessive major gene effects and significant polygenic background determinations have been found for several variables, including urinary kallikrein excretion, intracellular sodium concentration, sodium-lithium countertransport and sodium-potassium cotransport. Each of these variables is related in some way to sodium or potassium metabolism, or both, and may help to improve the understanding of a possibly inherited susceptibility to hypertension that is related to dietary electrolyte intake. A second major group of factors involving familial predisposition to hypertension include lipid abnormalities (increased very-low- and low-density lipoprotein cholesterol and decreased high-density lipoprotein cholesterol); increased fasting insulin levels or insulin resistance, or both; obesity (especially central or upper body obesity); and multiple environmental factors influencing these metabolic systems, including dietary fat, carbohydrate and calorie intake; physical exercise; and certain antihypertensive medications that adversely affect lipid metabolism and glucose tolerance. Some studies even suggest a possible link between these two large groups of factors (electrolyte metabolism and lipid-insulin metabolism). Hypertriglyceridaemia and hyperinsulinaemia are both significantly correlated with increased levels of several cation-flux tests. It is recommended that studies of human hypertension apply these biochemical profiles to study sibships with two or more hypertensive siblings as a cost-effective initial approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus↗
PubMed1989

A gene for high urinary kallikrein may protect against hypertension in Utah kindreds.

The inheritance of 12-hour overnight total urinary kallikrein excretion and its association with family history of essential hypertension were studied in 405 normotensive adults and 391 youths in 57 Utah pedigrees. Total urinary kallikrein excretion was highly familial with 51% of the total variance attributable to a dominant allele for high total urinary kallikrein excretion and 27% attributable to the combined effects of polygenes and shared family environment. An estimated 28% of the population has one or two copies of the dominant allele for high total urinary kallikrein excretion (2.3 SD units higher than the low homozygotes). About 83% of the population could be assigned to one of the two genotypic populations. Individuals with the high total urinary kallikrein excretion genotype were significantly less likely to have one or two hypertensive parents (relative odds = 0.56, p = 0.042). We conclude that a dominant allele expressed as high total urinary kallikrein excretion may be associated with decreased risk of essential hypertension. Further studies should be performed to confirm this finding and to test for interactions between this apparently protective gene and other genetic and environmental determinants of essential hypertension.

Adolescent↗
PubMed1989

Evidence for heritability of non-modulating essential hypertension.

We have previously described a subset of subjects with essential hypertension who fail to appropriately modulate renal vascular and adrenal reactivity with changes in dietary sodium and in response to infused angiotensin II (Ang II). In this paper, we studied these responses in 13 unselected hypertensive subjects in whom the family history of hypertension had been carefully detailed. Nine of these 13 subjects had a positive family history (FH+) for hypertension and had significantly smaller decrements in renal blood flow with Ang II infusion than the four subjects who had a negative family history (FH-) (-84 +/- 16 ml/min/1.73 m2 for FH+ vs. -149 ml/min/1.73 m2 for FH-, p = 0.024). These FH+ subjects also showed smaller increases in renal blood flow with increases in dietary sodium than FH- subjects (7 +/- 10 ml/min/1.73 m2 vs. 72 +/- 24 ml/min/1.73 m2, respectively; p = 0.014). When classified as modulators or non-modulators by previously established criteria, all seven non-modulators were FH+, and seven of nine FH+ subjects were non-modulators. This association between non-modulation and family history of hypertension is significant (p = 0.021). To further clarify the association between non-modulation and family history of hypertension, we have studied the renal blood flow response to Ang II in 31 hypertensive siblings from 14 sibships. Twenty-five of these 31 subjects (81%) behaved as non-modulators (p = 0.008 compared with expected value in an unselected hypertensive population). Additionally, strong concordance of non-modulation between sibling pairs was observed (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1989

Recessive inheritance of a relative fat pattern.

We defined a relative-fat-pattern index (RFPI) as the ratio of subscapular skinfold thickness to the sum of subscapular and suprailiac skinfold thicknesses and computed RFPI for 774 adults (age greater than or equal to 25 years) in 59 pedigrees ascertained through cases of cardiovascular disease. Likelihood analysis of RFPI supported recessive inheritance of an allele with a frequency of 46%, which elevated mean RFPI from .412 to .533 when homozygous. The analysis apportioned the variance in RFPI as 42.3% due to the major locus, 9.5% due to polygenic inheritance, and 48.2% due to random environmental effects. Homozygotes for the recessive allele tended to have small suprailiac skinfold thicknesses rather than large subscapular skinfold thicknesses. Homozygotes were more frequent in younger than in older cases of obesity, coronary heart disease, essential hypertension, and diabetes mellitus; the increase was significant for all but diabetes.

Adolescent↗
PubMed1989

A rapid micro-scale procedure for determination of the total lipid profile.

We describe a one-day micro-scale procedure for determining the total lipid profile. Only 0.55 mL of plasma is needed for complete quantification of total cholesterol (TC), triglyceride (TG), and all lipoproteins. After precipitation with dextran sulfate and magnesium, the high-density lipoprotein (HDL) fraction was separated by centrifugation in an Eppendorf microcentrifuge. Very-low-density lipoprotein (VLDL) was separated from low-density lipoprotein (LDL) plus HDL in a Beckman TL 100 ultracentrifuge. TC, TG, and cholesterol in different lipoprotein fractions were measured enzymatically in a Baker "Encore II" automated analyzer. CVs, both within-day and day-to-day, were less than 3% for TG and TC, and less than 5% for HDL-C determinations. CVs for LDL-C and VLDL-C were less than 7.5% and 15%, respectively. Results by our micromethods (n = 66) agreed well with those by the conventional methods used at the Northwest Lipid Research Center, which are standardized against the Reference Methods of the Centers for Disease Control. Coefficients of correlation between the two methods were 0.98 for TC, 1.0 for TG, 0.98 for HDL-C, 0.94 for LDL-C, and 0.96 for VLDL-C. Results of electrophoresis on agarose gel and radioactivity-recovery studies indicate that our micro-centrifugation and slicing procedures result in clean separation of VLDL from other lipoproteins.

Autoanalysis↗