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Biomedical subjects

B Falkner

Publications and source records attributed to B Falkner.

At least 55 records · Page 3Linked to original sources
PubMed1993

Hypertension in childhood and adolescence.

Through the benefit of a large body of normative data on blood pressure throughout childhood, along with the clinical practice of regular blood pressure measurement in the young, mild elevation of blood pressure can be detected in the young. Unlike secondary hypertension in the young which is more severe, slight to mild elevations in blood pressure during childhood may be an early expression of essential hypertension. Mildly elevated blood pressure in the young is usually associated with other risk factors including obesity, family history of cardiovascular disease, and metabolic alterations in lipids and insulin. Environmental factors, which include health related behaviors can modulate the expression of the risk factors including elevated blood pressure. The extent to which the health behaviors of diet and exercise can be modified in the young may be important for risk factor intervention during the early phases of hypertension.

Adolescent↗
PubMed1992

Hyperinsulinemia and blood pressure sensitivity to sodium in young blacks.

The relationship of blood pressure sensitivity to sodium with plasma insulin concentration was examined in young adult (22 to 28 yr) blacks (N = 45). The study included normotensive and borderline hypertensive subjects. Blood pressure sensitivity to sodium was determined by the change in mean blood pressure after 14 days of sodium loading (10 g of NaCl daily plus usual diet). Plasma insulin concentration was determined during an oral glucose tolerance test (OGTT). The correlation of fasting plasma insulin concentration with blood pressure or blood pressure sensitivity to sodium was not statistically significant. There was a significant correlation (after adjustment for adiposity) of blood pressure sensitivity to sodium with both the sum of insulin (r = 0.41; P < 0.01) and the 60-min plasma insulin concentration during the OGTT. The plasma insulin concentration at 60 min during the OGTT correlated significantly with the change in mean arterial pressure over a 5-yr interval (r = 0.36; P < 0.02). There was a similar significant correlation of blood pressure sensitivity to sodium with change in mean arterial pressure over 5 yr (r = 0.48; P < 0.001). These data demonstrate an association of hyperinsulinemia and blood pressure sensitivity to sodium in the young. The data also suggest that insulin may contribute to the pathogenesis of hypertension in the black population.

Adult↗
PubMed1991

Insulin resistance in the spontaneously hypertensive rat.

To determine experimentally if insulin resistance is associated with spontaneously occurring hypertension, insulin-stimulated glucose metabolism was studied in an animal model of genetic hypertension. The spontaneously hypertensive rat (SHR) and its genetic control, the Wistar-Kyoto strain (WKY) were studied with the euglycemic hyperinsulinemic clamp technique. Clamp studies demonstrated reduced insulin-stimulated glucose uptake in SHR (P less than .001). These data indicate that SHR is insulin-resistant when compared with WKY. A reduction of insulin-stimulated glucose metabolism occurred in older animals of both strains, providing evidence of an aging effect on insulin-stimulated glucose metabolism. However, the reduction of insulin-stimulated glucose metabolism was more pronounced in the hypertensive animals. This study demonstrates the presence of peripheral (skeletal muscle) insulin resistance in the SHR.

Animals↗
PubMed1991

Blood pressure response to mental stress.

In a series of studies to explore the relationship of mental stress with blood pressure regulation, we have found that offspring of hypertensive parents exhibit a greater cardiovascular response to the stress of mental arithmetic compared to offspring of normotensive parents. The response is also greater in both adolescents and adults with borderline hypertension. However, there are racial differences in the stress-response pattern. In studying the interaction of sodium sensitivity with stress-reactivity, our data indicates that the cardiovascular response to central stress is not altered by sodium balance. The response to mental stress may be a useful marker for essential hypertension (EH), but does not appear to represent an isolated mechanism in the pathogenesis of EH.

Blood Pressure↗
PubMed1991

Interaction of sodium sensitivity and stress in young adults.

The interaction of sodium sensitivity and stress-induced cardiovascular reactivity was studied in white and black young adults aged 18-23 years. The cardiovascular response to difficult mental arithmetic was measured before and after 14 days of oral sodium loading (10 g NaCl/day added to the usual diet). A sodium-sensitive blood pressure response occurred in 18.4% of whites and 37.3% of blacks. A significant correlation between blood pressure change and sodium excretion occurred in the sodium-sensitive group (r = - 0.28, p less than 0.01). High sodium intake did not augment blood pressure or heart rate response to the beta-adrenergic-mediated stimulus of mental arithmetic in the population, which was grouped by blood pressure, race, or sodium sensitivity.

Adolescent↗
PubMed1991

Blood pressure patterns in the first three days of life.

Current blood pressure data for healthy newborn infants consist primarily of single measurements of systolic and diastolic pressure in the first 48 hours of life. The purpose of this study was to determine if blood pressure levels are stable or are changing during the first few days of life. To determine blood pressure level and trend, indirect blood pressure was measured on day 1 through day 3 of life in all infants admitted to the well newborn nursery at Hahnemann University Hospital in Philadelphia. Systolic pressure correlated significantly with birthweight on day 1 of life (P less than .03). Repeated measures analysis of variance demonstrated a significant increase in both systolic and diastolic pressures over the first 72 hours of life (P less than .001). There was no difference in blood pressure among racial groups (black, Hispanic, white, Asian). In healthy newborns, there was no correlation of blood pressure with maternal conditions: toxemia, diabetes, substance abuse. These data demonstrate that blood pressure correlates with birthweight in well newborns. There is, however, a significant progressive increase in both systolic and diastolic blood pressure over the first 3 days of life, regardless of birthweight or maternal conditions.

Analysis of Variance↗
PubMed1990

Relationship between plasma renin concentration and atrial natriuretic peptide in the human newborn.

To test the hypothesis that atrial natriuretic peptide (ANP) concentration in the newborn is negatively related to plasma renin concentration (PRC), as it is in the adult, we measured the concentration of both substances in the same plasma sample. We studied 24 well term newborns and 20 samples of umbilical venous blood from normal deliveries. Both ANP and PRC are elevated in newborn plasma, but not in umbilical venous plasma. ANP levels on the second day of life are greater than either day 1 or day 3. Linear regression of ANP and PRC demonstrates a highly significant negative correlation [r = -0.65, p less than 0.001], which suggests that the suppression of the renin-angiotensin system by ANP seen in the adult may be intact in the newborn. ANP may act to blunt the effects of the augmented renin-angiotensin system of the newborn and promote normal neonatal diuresis.

Atrial Natriuretic Factor↗
PubMed1990

Effect of chronic sodium loading on cardiovascular response in young blacks and whites.

The effect of long-term oral sodium loading on blood pressure and on stress-induced cardiovascular response was studied in normotensive and marginally hypertensive young adults. The 121 subjects, 18-23 years old, included 38 whites and 83 blacks. Blood pressure and heart rate response to the stress of mental arithmetic was measured before and after 14 days of sodium load, which consisted of 10 g NaCl/day added to the usual diet. A sodium-sensitive response to sodium load occurred in 18.4% of whites and 37.3% of blacks. Sodium-insensitive subjects had a higher rate of sodium excretion (p less than 0.001). Sodium-sensitive hypertensive subjects had a significantly greater weight gain (p less than 0.001). A significant correlation between blood pressure change and sodium excretion (r = -0.28, p less than 0.01) occurred in the sodium-sensitive group. The high sodium intake did not augment the blood pressure or heart rate response to the beta-adrenergic-mediated stimulus of mental arithmetic in the population when grouped by blood pressure, race, or sodium sensitivity. These results suggest that blood pressure increase in response to sodium load, particularly in blacks, is related to functional changes in peripheral vascular resistance.

Administration, Oral↗
PubMed1990

Differences in blacks and whites with essential hypertension: biochemistry and endocrine. State of the art lecture.

Overall, there is agreement that the origins of hypertension have a genetic basis. The genetic factors interact with environmental factors that influence expression and intensity of the disorder. As summarized in Table 1, there is evidence from the literature to identify pathways for the development of hypertension in blacks. Organ pathology, characteristic of the clinical phenotypic hypertension, consists of increased peripheral vascular resistance and left ventricular hypertrophy, and, particularly in blacks, nephrosclerosis. In this scheme, an intermediate phenotype is a biochemical or endocrine marker of gene expression that participates in the regulation of blood pressure. Intermediate phenotypic characteristics of essential hypertension include sodium sensitivity, adrenergic activity, cation transport, and endocrine function including renin-angiotensin-aldosterone, kallikrein-kinin, and prostaglandin. Another intermediate phenotype to be included in this discussion is insulin resistance. These intermediate phenotypes of cell and subcellular function are regulated by candidate genes. Alternatively, an intermediate phenotype can be expressed in response to another intermediate phenotype. For example, sodium sensitivity could be mediated by the cation transport mechanism of Na,K-ATPase, or insulin resistance could be induced by an elevated level of adrenergic activity. Gene expression of the intermediate phenotype is also modulated by environmental factors such as dietary sodium, potassium, or calcium, and social stresses or patterns of physical activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMed1990

Red blood cell Na+ transport as a predictor of blood pressure response to Na+ load in young blacks and whites.

The present study was designed to investigate the role of abnormalities in red blood cell sodium-potassium-chloride (Na-K-Cl) cotransport and Na+ pump as predictors of the pressor response to chronic oral Na+ loading in young whites and blacks. Subjects were healthy adults from 18 to 23 years of age and included normotensive whites (n = 24) and normotensive blacks (n = 35). Red blood cell transport studies were performed before Na+ loading. The Na+ load consisted of 10 g NaCl daily added to the usual diet. A sodium-sensitive response was defined as an increase of 5 mm Hg or more in mean arterial pressure after the Na+ load; a sodium-insensitive response was a less than 5 mm Hg increase in mean arterial pressure. A sodium-sensitive response occurred in 16% of whites and 57% of blacks. Black subjects have a significantly lower (p less than 0.005) maximal rate of furosemide-sensitive Na+ efflux and a higher Km for cellular Na+ (p less than 0.05) to activate Na-K-Cl cotransport than white subjects. Normotensive blacks with sodium-sensitive blood pressure response had a higher Km (14.4 +/- 6 mmol/l cell, n = 17, mean +/- SD) to activate the cotransport than sodium-insensitive blacks (9.9 +/- 3.7 mmol/l cell, n = 13, p less than 0.001). Normotensive whites had a significantly lower red blood cell Na+ content (p less than 0.05) and a higher maximal rate of cotransport (p less than 0.005) than young normotensive blacks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Insulin resistance and blood pressure in young black men.

Insulin resistance, independent of obesity or non-insulin-dependent diabetes mellitus, has been demonstrated to be associated with high blood pressure. To determine if insulin resistance could be an antecedent to hypertension in a high-risk population, we studied normotensive (112 +/- 12/70 +/- 10 mm Hg) and borderline hypertensive (135 +/- 8/85 +/- 5 mm Hg) lean young black men (22-26 years old) with the euglycemic hyperinsulinemic clamp technique. All subjects had clinically normal oral glucose tolerance. Body mass index and percent adipose mass were the same in both groups. Fasting plasma insulin concentration was significantly higher in the borderline hypertensive group (p less than 0.01). Insulin-directed exogenous glucose metabolism at the same degree of steady-state hyperinsulinemia was significantly lower in the borderline hypertensive group (5.98 +/- 2.22 versus 8.22 +/- 1.96 mg/kg/min; p less than 0.01). For the total population, a significant inverse correlation existed between the glucose infusion rate and systolic blood pressure (p less than 0.01). These data indicate that there is a relation between insulin-mediated glucose uptake and blood pressure. Furthermore, in this high-risk population insulin resistance may precede the onset of established essential hypertension.

Adult↗
PubMed1990

Beckwith-Wiedemann syndrome. Renal pathology at 4 months of age.

This report describes a child with nephromegaly and Beckwith-Wiedemann syndrome. The type and extent of the renal involvement could not be determined by imaging techniques. A pathologic examination of the renal biopsy tissue in this case demonstrated diffuse interstitial dysplasia. This is the first early pathologic description of the renal pathologic process in a living child with Beckwith-Wiedemann syndrome. The renal pathology indicates that children with this syndrome who survive other complications of the disorder have the potential for progressive renal disease.

Beckwith-Wiedemann Syndrome↗
PubMed1989

Race differences in stress-induced reactivity in young adults.

The cardiovascular response to the stress of mental arithmetic was studied in young Black and White adults. Stress-induced reactivity was studied before and following 14 days of oral sodium loading (10 gm NaCl per day). Marginal hypertensives, both Black and White, had greater systolic blood pressure (SBP) levels (p less than 0.001) and greater diastolic blood pressure (DBP) levels (p less than 0.01) in response to stress. Whites had a greater SBP level during mental stress than Blacks (p = 0.008) and greater reactivity (change from baseline; p less than 0.001). The prevalence of sodium sensitivity was greater in Blacks (37.3%) than in Whites (18.4%). Sodium loading did not augment the BP reactivity to the mental stress in any of the racial or BP groups. These data demonstrate racial variation in the cardiovascular response to centrally mediated adrenergic stimuli. The results also suggest that mild BP elevation in Blacks may be regulated through changes in vascular resistance.

Adolescent↗
PubMed1989

Forearm hemodynamics at rest and stress in borderline hypertensive adolescents.

Cardiovascular adaptations to mild elevations of blood pressure (BP) may occur early in the development of essential hypertension (EH). We used strain gauge plethysmography to study forearm hemodynamics in adolescents. Ten normotensive males (N) were compared to ten males with borderline hypertension (H). Measurements of forearm blood flow (FBF) were obtained after supine rest, during ten minutes of mental stress (mental arithmetic) and five minutes post stress. Mean arterial pressure (MAP) and forearm vascular resistance (FVR) were calculated. The H maintained higher MAP and FVR (P less than or equal to .05) throughout the study. The vascular response patterns were assessed by comparing the slopes of the linear regression equation FBF = a ln FVR + b (where a = slope and b = intercept). From baseline to stress, the N exhibit a significant change in slope (P less than .05), shifting to a decrease in FVR per unit FBF change. However, the H maintain a constant slope and FVR per unit FBF change remains constant. The study suggests that a primary peripheral vascular abnormality may be present even in the young with marginally elevated BP.

Adolescent↗
PubMed1989

The hypertensive adolescent.

The hypertensive adolescent requires a careful blood pressure evaluation. In most cases, extensive diagnostic studies will not be necessary, particularly if the patient exhibits characteristics of early essential hypertension. On the other hand, further evaluation should not be withheld in the absence of risk factors or the presence of significant hypertension. A management plan that includes patient education is appropriate for all adolescents with hypertension. In some, but not all, hypertensive adolescents, a limited course of medication may be beneficial.

Adolescent↗