Biomedical subjects
H Kuida
Publications and source records attributed to H Kuida.
Different plasma ionized calcium correlations with blood pressure in high and low renin normotensive adults in Utah.
Plasma ionized calcium levels have been shown to be lower than normotensive control levels in hypertensive patients with low plasma renin activity and higher than control levels in hypertensive patients with high renin activity; they did not differ between high and low plasma renin activity groups of normotensive controls. To see if ionized calcium may have different relationships with blood pressure across renin categories in normotensive individuals, plasma ionized calcium was measured on 875 healthy individuals, ages 3 to 83, who had never been diagnosed as having hypertension. Blood pressures were measured in the sitting, standing, and supine positions, along with pressures measured during two stress maneuvers: isometric handgrip and a 50 degrees tilt from a supine position. There was no linear correlation of blood pressure with plasma ionized calcium in the entire sample of youths or adults. However, after dividing the adults into tertiles based on plasma renin activity, there were significant inverse correlations between ionized calcium and systolic and diastolic blood pressure in the low renin group (r = -0.16 to -0.25, P less than or equal to .05), while the systolic blood pressure correlations were significantly positive in the high renin group (r = 0.14 to 0.22, P less than or equal to .05). Adults with normal renin levels did not have any significant correlations of plasma ionized calcium with blood pressure. These confounding effects of renin were greater for systolic than for diastolic blood pressure. These correlations within renin tertiles occurred even though there were no differences in mean blood pressure, plasma ionized calcium, total plasma protein and plasma sodium across renin categories.(ABSTRACT TRUNCATED AT 250 WORDS)
Genetic traits related to hypertension and electrolyte metabolism.
The genetic and cultural heritability and intercorrelation of traits related to hypertension have been carried out in 98 Utah pedigrees (2,500 person) and 58 sibships with two or more hypertensive persons (131 hypertensive persons). Although none of these traits has been established as a marker for "sodium-sensitive hypertension," many of them are related at least indirectly to both electrolyte metabolism and risk of hypertension. Significant recessive monogenic effects and high total heritability (52-84%) were found for urinary kallikrein, high fat pattern index, intraerythrocytic sodium, Na-Li countertransport, and ouabain binding sites. Familial correlations more strongly attributable to shared environment than to genetic effects were found for Na,K-ATPase pump activity, intraerythrocytic magnesium, plasma digoxin-like factor, plasma renin activity, and plasma sodium concentration. All anthropometric variables tested showed highly significant genetic heritability with low and insignificant shared family environmental effects. Several of the genetically determined cellular cation tests also correlated with other genetic traits including plasma lipids, anthropometric measurements, and other cellular cation tests. Among hypertensive individuals with familial dyslipidemic hypertension, plasma insulin levels correlated with obesity and lipid abnormalities and with several cellular cation flux tests associated with hypertension.
Genetics of hypertension: what we know and don't know.
Human arterial hypertension is likely a multifactorial trait resulting from multiple measurable monogenes, blended polygenes, shared family environment, and individual environment. Familial aggregation of hypertension and familial correlation of blood pressure appears to be more due to genes than to shared family environment. Total genetic heritability of 80% with some recessive major gene effects have been found for several traits associated with hypertension including urinary kallikrein excretion, intraerythrocytic sodium, and sodium-lithium countertransport. Other interesting factors regarding hypertension genetics include: non-modulation of the renin angiotensin system, intralymphocytic sodium, ionized calcium, and several genetic markers such as haptoglobin, HLA, and MNS blood type. Probably the most clinically useful information regarding the genetics of hypertension is evolving in several studies reporting a strong association of hypertension with dyslipidemia, diabetes, and obesity.
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.
Hypertension: genetics and nutrition.
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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.
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.
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.
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.
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)
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.
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.
Family history as an independent risk factor for incident coronary artery disease in a high-risk cohort in Utah.
To test independence of family history of coronary artery disease (CAD) as a risk factor for the development of new clinical CAD, data collected at 2 clinic visits on 1,196 men and women, ages greater than 20 years, were analyzed using Cox proportional hazard method. During a mean follow-up of 2.5 years, 16 new CAD cases were observed. After adjustment for age, sex, total cholesterol, high density lipoprotein cholesterol, hypertension, diabetes, cigarette smoking and body mass index, family history remained a highly significant predictor of future CAD (p = 0.0017). Only age was a more significant covariate (p = 0.0001) than family history. Sex (p = 0.00074) and serum total cholesterol (p = 0.015) also contributed significantly to CAD incidence while high density lipoprotein cholesterol, hypertension, diabetes, body mass index and several interaction terms did not improve the prediction in this population. These results provide evidence for the existence of other heritable risk factors which appear to contribute strongly to the occurrence of early CAD in many high-risk families.
Familial dyslipidemic hypertension. Evidence from 58 Utah families for a syndrome present in approximately 12% of patients with essential hypertension.
Population-based sibships with essential hypertension diagnosed before the age of 60 years are being screened in Utah to find two or more hypertensive siblings with the same biochemical abnormality as a clue to an inherited cause for their specific type of hypertension. Among 131 hypertensive subjects in 58 sibships, concordant abnormalities in fasting serum lipid concentrations were observed in two or more siblings in 48% of the sibships. After adjusting for effects of antihypertensive medications, abnormal values reported in only 10% of the Lipid Research Clinics data were observed in 30% of patients for serum triglycerides, 19% for serum low-density lipoprotein cholesterol, and 39% for high-density lipoprotein cholesterol. More than one lipid level was abnormal in almost all concordant sibships, suggesting an association between hypertension and a syndrome of mixed lipid abnormalities, probably familial combined hyperlipidemia (renamed "familial combined dyslipidemia" because of common low high-density lipoprotein cholesterol levels). We conclude that familial dyslipidemic hypertension may be a specific syndrome with lipid abnormalities more severe than blood pressure elevations.
Paradoxical increase of ventricular fibrillation threshold in response to coronary sinus obstruction.
We determined the ventricular fibrillation threshold (VFT) changes in response to graded coronary sinus (CS) obstruction in 13 chloralose-anesthetized dogs with fixed heart rate (150 min-1, mean systemic arterial pressure (80 mm Hg), and cardiac index (100 ml/min.kg-1 body weight). VFT in milliamperes (VFTmA) increased linearily with CS pressure (CSP) increases up to 41.2 +/- 1.4 mm Hg (VFTmA = 6.5 + 0.14 CSP mm Hg, p less than 0.01). Total coronary venous effluent (CBF) did not change significantly, suggesting compensatory coronary vasodilation. Myocardial O2 consumption also remained unchanged. At higher CSP, both CBF and VFT declined precipitously (VFTmA = 20.9 - 0.27 CSP mm Hg, p less than 0.02). With simultaneous increases of systemic arterial along with CSP, VFT increased again along with the CSP-induced reduction of gradient until it reached 42.8 +/- 3.2 mm Hg. We conclude that with coronary venous obstruction, despite coronary perfusion gradient reduction to about 40 mm Hg, CBF remains constant. This constant flow vasodilation is associated with substantial (82%) VFT increase. The mechanism may involve enhanced homogeneity of CBF distribution and increased extracellular fluid.
Definition of genetic factors in hypertension: a search for major genes, polygenes, and homogeneous subtypes.
Essential hypertension is a heterogeneous group of disorders with different causes. This report reviews approaches taken and results found in current studies of the genetic and environmental determinants of essential hypertension. Recent observations from the University of Utah Cardiovascular Genetics Research Clinic and published data from other studies are cited. Several biochemical tests show strong associations with hypertension and substantial major gene and/or polygenic determination including: urinary kallikrein excretion, intracellular sodium concentration, sodium-lithium countertransport, plasma haptoglobin phenotypes, MN blood groups, and familial dyslipidemia.
Hypertension and sodium-lithium countertransport in Utah pedigrees: evidence for major-locus inheritance.
Likelihood analysis was used to test for evidence that an allele at a major locus elevates rates of sodium-lithium countertransport (SLC) in a sample of 1,989 members of 89 Utah pedigrees. The pedigrees were ascertained through two or three sibs who died of stroke before age 74 years (stroke pedigrees), through hypertensive and normotensive probands of the Salt Lake Center of the Hypertension Detection and Followup Program (HDFP pedigrees), or through men who suffered a myocardial infarction before age 55 years (coronary pedigrees). Major-locus inheritance could be rejected in the total sample; transmission probability estimates of tau1 = .972, tau2 = .520, tau3 = .185 differed significantly from Mendelian transmission specified by tau1 = 1, tau2 = 1/2, tau3 = 0. However, heterogeneity between ascertainment groups was significant (chi2(18) = 40.06, P less than .01) and justified analysis within subsets of the sample. In the stroke pedigrees, evidence of major-locus inheritance was not found; polygenic heritability was estimated as .647. In the HDFP pedigrees, estimates of tau1 = .987, tau2 = .430, tau3 = .506 differed significantly from Mendelian transmission; the inferred model consisted of a mixture of two distributions incompatible with both Mendelian and environmental transmission but compatible with polygenic inheritance within distributions. In the coronary pedigrees, the hypothesis of Mendelian transmission could not be rejected. In the coronary pedigrees, the evidence supported an incompletely recessive allele with a frequency of .227 which elevated the level of SLC to a mean of .530 mmol/liter RBC/h.(ABSTRACT TRUNCATED AT 250 WORDS)