Renal hemodynamic changes after beta-blocker-diuretic combination therapy in azotemic hypertensive patients

The effects of beta-blocker therapy with either nadolol or propranolol were compared during therapy with hydrochlorothiazide (HCTZ) 50 mg b.i.d. on glomerular filtration rate (GFR), effective renal plasma flow (ERPF), effective renal blood flow (ERBF), blood pressure, and heart rate in 22 patients with essential hypertension and mild to moderate renal insufficiency. The clearances of inulin and para-aminohippurate (PAH) were used to estimate renal hemodynamic measurements. These parameters were determined after 2 weeks of HCTZ plus placebo and at 1, 3, and 6 months after the addition of beta-blocker to HCTZ. Significant reductions in blood pressure and heart rate were seen, but no significant reduction of renal hemodynamics were seen with either beta-blocker-HCTZ combination. Since 50% of the patients in each drug group were either Black or White, hemodynamic data were also analyzed by race. One month after beta-blocker addition there was a slight reduction of GFR in both Whites (47 +/- 6 vs. 40 +/- 5 ml/min, p greater than .05) and Blacks (44 +/- 5 vs. 40 +/- 6 ml/min, p less than .05). By month 6, GFR in Whites rose to 57 +/- 9 ml/min, whereas in Blacks it fell significantly to 36 +/- 6 ml/min (p less than .01). Similarly, at month 1, ERBF declined by 12% and 13% in Whites and Blacks, respectively. However, at month 6, ERBF rose by 28% in Whites and remained 11% lower in Blacks, p less than .05. In summary, in the group as a whole neither beta-blocker significantly altered renal hemodynamics when added to HCTZ therapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Population differences in the pattern of familial aggregation for sex hormone‐binding globulin and its response to exercise training: The HERITAGE family study

Familial influences were investigated for baseline sex hormone‐binding globulin (SHBG) and its response (post‐training minus baseline) to a 20‐week endurance exercise training program. One hundred, eighty‐four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex‐by‐generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h² = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE (h² = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size. Am. J. Hum. Biol. 13:832–837, 2001. © 2001 Wiley‐Liss, Inc.     

Ethnic disparities in the perception of ethical risks from psychiatric genetic studies

To examine if ethnic differences in concerns about unfavorable consequences from psychiatric genetic studies, existing between non‐Hispanic Black and White populations, persist among participants in an actual genetic study of bipolar disorder. Historically, minority subjects have been less willing to participate in such studies. Participants in the US Bipolar Genome Study (BIGS) were assessed on six items of concerns in the Questionnaire on Genetic Risk (QGR). Each item had five response categories, ranging from “not at all” concerned to “very concerned.” Responses from Black (N = 188) and White participants (N = 1,065) formed the base for this analysis. Concerns about unfavorable consequences of conducting psychiatric genetic studies were prevalent in the whole sample. Concern for medical insurance was most prevalent (63.4%), followed by job concern (58.8%) and stigma (57.4%). Racial discrimination was less prevalent (28.1%). Blacks endorsed significantly stronger concerns for all consequences except the medical insurance item (P < 0.008). The most significant ethnic disparity in concerns was for racial discrimination (P < 0.0001). Associations between levels of concern and ethnicity remained significant after adjustments for other factors in multivariate models. Ethnic differences (Blacks vs. Whites) in perceived concerns about unfavorable consequences from participation persist among participants in an actual psychiatric genetic study. This suggests that other factors may play a more critical role in the decision not to participate. Future studies should investigate more comprehensive sources of barriers to consenting for ongoing psychiatric genetic studies in representative samples, incorporating assessments from non‐participants as well as participants. © 2011 Wiley‐Liss, Inc.     

Familial resemblance for glucose and insulin metabolism indices derived from an intravenous glucose tolerance test in Blacks and Whites of the HERITAGE Family Study

Type 2 diabetes mellitus (T2DM), characterized by hyperglycemia, is a complex disease primarily caused by impairment in insulin sensitivity (S_I) and insulin secretion. While a strong genetic component for T2DM is well established, there are few reports on racial differences in the magnitude of the genetic effects of T2DM and indices of glucose and insulin metabolism. We report here on the familial resemblance for traits related to glucose metabolism at pre-exercise training levels in 492 members from 99 sedentary White families and 259 members from 108 Black families participating in the multicenter HERITAGE Family Study. All these traits were obtained from the frequently sampled intravenous glucose tolerance test (IVGTT). They include glucose disappearance index (K_g), an overall index for glucose tolerance, acute insulin response to glucose (AIR_Glucose) which is an index for insulin secretion, and those derived from the minimal model including S_I and the disposition index (DI). DI, derived as the product of S_I and AIR_Glucose, is a measure of the activity of the B-cells adjusted for insulin resistance. After adjustment for age, sex, and body mass index, the maximal heritability estimates in Blacks (Whites) are 48±14% (25±8%) for K_g, 44±14% (46±8%) for AIR_Glucose, 38±12% (44±8%) for S_I and 32±14% (24±8%) for DI. Interestingly, Blacks have higher heritability for overall glucose tolerance than Whites but there is no race difference in heritability estimates for insulin sensitivity or insulin secretion.     

Buoyancy of African black and European white males

Twenty-six male swimmers (13 Blacks, 13 Whites) matched for age, weight, and stature were subjects in the comparison of anthropometric characteristics and horizontal and vertical buoyancies. Subjects were tested in a swimming pool in the horizontal position. The time necessary for the body to return to the vertical position defined horizontal buoyancy. Vertical buoyancy was the hydrostatic lift necessary to maintain the subject immersed to the nose. The results indicated similarities in arm span, trunk flexibility, and full inspiration and exhalation of Black and White subjects. However, there were differences in body fat distribution (P ≤ 0.05) and buoyancies (P ≤ 0.01), with Whites storing more fat and having better buoyancy than Blacks. Am. J. Hum. Biol. 9:87–92 © 1997 Wiley-Liss, Inc.     

Effects of ethnicity,gender, obesity,and age on central fat distribution: Comparison of dual x-ray absorptiometry measurements in white,black, and Puerto Rican adults

Population based studies relying primarily upon anthropometric surrogates of fat distribution have shown that central or upper-body adiposity is related to ethnicity, gender, age, and total body fatness. As an improvement over anthropometry, dual x-ray absorptiometry (DXA) provides more precise measurements of fat mass (FM) in the total body and trunk. DXA was performed on 510 apparently healthy White (81 females (f), 64 males (m)), Black (94 f, 79 m), and Puerto Rican (102 f, 100 m) adults aged 20–75 years in order to determine and compare the effects of race, gender, age, and total FM on trunk FM. Trunk FM was greater for Blacks and Puerto Ricans than Whites, irrespective of gender (P < 0.014). Puerto Rican males and females had a greater proportion of fat in the trunk (%TrFM) than Whites or Blacks (P < 0.001), and Whites and Blacks were similar with respect to %TrFM (P > 0.67). Females had less %TrFM than males in all three ethnic groups (all P < 0.001). Based on multiple regression analysis, ethnicity did not affect the relationship of trunk and total FM among males (P > 0.16), but the coefficient for total FM was larger for Puerto Rican compared to Black females (P = 0.043). Trunk FM increased with age in Whites and Puerto Ricans (P < 0.02), but not Blacks (P > 0.24). The effects of age did not differ by gender or ethnicity among Whites and Puerto Ricans (P > 0.10). Adjustment for total FM and age eliminated ethnic and gender differences in trunk FM (all P > 0.37). The results suggest that the high levels of central adiposity observed among Blacks and Hispanics relative to Whites reflect patterns of generalized obesity observed in the respective populations. Patterns of accumulation of truncal FM with increasing age and obesity may not be generalizable to all ethnic groups. Am. J. Hum. Biol. 10:361–369, 1998. © 1998 Wiley-Liss, Inc.     

Age at menarche and the evidence for a positive secular trend in urban South Africa

Menarcheal age was estimated for 287 (188 Black; 99 White) urban South African girls born in Soweto‐Johannesburg in 1990. The median menarcheal age for Blacks was 12.4 years (95% confidence interval (CI) 12.2, 12.6) and 12.5 years (95% CI 11.7, 13.3) for Whites. Data from six studies of menarcheal age, including the current study, were analyzed to examine the evidence for a secular trend between 1956 and 2004 in urban South African girls. There was evidence of a statistically significant secular trend for Blacks, but not Whites. Average menarcheal age for Blacks decreased from 14.9 years (95% CI 14.8, 15.0) in 1956 to 12.4 years (95% CI 12.2, 12.6) in the current study, an average decline of 0.50 years per decade. Fewer data were available for Whites, but average menarcheal age decreased from 13.1 years (95% CI 13.0, 13.2) in 1977 to 12.5 years (95% CI 11.7, 13.3) in the current study, an average decline of 0.22 years per decade. The diminishing age at menarche and the current lack of difference between Blacks and Whites is probably reflective of the continuing nutritional and socio‐economic transition occurring within South Africa. Am. J. Hum. Biol., 2009. © 2008 Wiley‐Liss, Inc.     

Investigation of the effect of brain-derived neurotrophic factor (BDNF) polymorphisms on the risk of late-onset Alzheimer's disease (AD) and quantitative measures of AD progression

BDNF is a functional candidate gene for AD, owing to its role in neuronal development and survival. The Val66Met (G196A), along with another C270T polymorphism has been associated with AD, however, the effects seem to be inconsistent across studies. We examined the association of the G196A and C270T polymorphisms with sporadic late-onset AD (LOAD) in a large American White cohort of 995 AD cases and 671 controls and an American Black cohort of 64 AD cases and 45 controls. We also examined the association of these polymorphisms with quantitative measures of AD progression, including age at onset (AAO), disease duration and Mini-Mental State Examination (MMSE) scores. No significant difference in allele, genotype or estimated haplotype frequencies was observed between AD cases and controls within the American White and Black cohorts for the G196A and C270T polymorphisms. However, the frequency of the 196*A allele was significantly lower in American Black subjects compared to Whites. While MMSE scores were significantly lower in C270T/CT carriers compared to C270T/CC subjects only among American Blacks, no such effect was observed among American Whites. The BDNF polymorphisms did not affect AAO or disease duration measures in American Whites or Blacks. Our finding does not support any association between the BDNF/G196A or C270T polymorphism and the risk of sporadic LOAD among American Whites or Blacks. The significant effect of the C270T polymorphism observed on MMSE scores among American Blacks needs to be further explored in a larger cohort.     

MMPI-168 profiles of male narcotic addicts by ethnic group and city

MMPI-168 profiles were obtained on 225 male narcotic addicts who were attending methadone maintenance clinics in Baltimore and New York City during 1983 and 1984. Data were collected on Black and White (Anglo, other than Hispanic) addicts in Baltimore and on Black, Hispanic, and White addicts in New York City. In general, the profiles indicated high levels of psychopathology, with particularly high elevations on the F, D, PD, PT, and SC scales. Consistent across cities and in agreement with earlier findings, profiles of Whites indicated somewhat more maladjustment than those for Blacks, while the profiles of Hispanics displayed essentially the same levels of disturbance as those for Whites. Comparisons by city revealed greater deviance for New York City subjects, a finding more evident among Whites than among Blacks.     

Type A behavior and its association with cardiovascular disease prevalence in Blacks and Whites: The Minnesota heart survey

Population-based surveys were conducted in 1985 and 1986 to measure the prevalence of coronary heart disease (CHD) history and risk factors in Black and White adults. Type A behavior was measured by the Jenkins Activity Survey (JAS). JAS scores were associated with age (negatively), education (positively), and sex (men>women) but were largely unrelated to CHD risk factors. Blacks had significantly lower age- and education-adjusted Type A and component scores than Whites, more so formen than women. Univariate analysis indicated that a history of angina and/or heart attack was positively associated with the Type A score in both Blacks and Whites. Following adjustment for known cardiovascular risk factors, Type A score remained positively and significantly associated with CHD prevalence. These findings are consistent with other cross-sectional studies and suggest that Type A behavior, as measured by the JAS, may increase the risk of CHD in both Blacks and Whites. Follow-up of these cohorts may help to clarify the complex relationship of Type A behavior to the risk of CHD.Supported by a National Heart, Lung and Blood Institute Grant (RO1-23727).     

Genetic and Shared Environmental Influences on Adolescent BMI: Interactions with Race and Sex

The present study uses a behavioral genetic design to investigate the genetic and environmental influences on variation in adolescent body mass index (BMI) and to determine whether the relative influences of genetic and environmental factors on variation in BMI are similar across racial groups and sexes. Data for the present study come from the National Longitudinal Study on Adolescent Health (Add Health), a large, nationally representative study of adolescent health and health-related behaviors. The Add Health sample contains a subset of sibling pairs that differs in levels of genetic relatedness, making it well suited for behavioral genetics analyses. The present study examines whether genetic and environmental influences on adolescent BMI are the same for males and females and for Black and White adolescents. Results indicate that genetic factors contribute substantially to individual differences in adolescent BMI, explaining between 45 and 85% of the variance in BMI. Furthermore, based on an analysis of opposite-sex sibling pairs, the genes that influence variation in adolescent BMI are similar for males and females. However, the relative importance of genetic and environmental influences on variation in BMI differs for males and females and for Blacks and Whites. Although parameter estimates could be constrained to be equal for Black and White males, they could not be constrained to be equal for Black and White females. Moreover, the best-fitting model for Black females was an ADE model, for White females it was an ACE model, and for males it was an AE model. Thus, shared environmental influences are significant for White female adolescents, but not for Black females or males. Likewise, nonadditive genetic influences are indicated for Black females, but not for White females or males. Implications of these results are discussed.     

Carrier detection in Sanfilippo syndrome type B: report of six families

Serum samples from 175 individuals in six Sanfilippo syndrome type B (SFB) families and 360 White controls were assayed for serum α-N-acetyl-D-glucosaminidase (NAG) activity. Only minimal overlap was observed between the controls' NAG activity distribution and that of the 12 obligate heterozygotes. The distribution of NAG activity was log transformed to reduce skewness, and segregation of family members with a prior risk of being a SFB carrier was well within expected limits. However, in one consanguineous family the NAG activity of both parents of one SFB obligate heterozygote was within the normal range for NAG activity. Plausible explanations for this finding are discussed. Additionally, the serum NAG activity of one control and her mother were found to lie within one standard deviation of the obligate heterozygote mean. These individuals are most probably carriers for SFB.     

Studies of random Black and White populations in North Carolina

As HLA testing is becoming a major vehicle for parentage determination with non-excluded, alleged fathers being compared to their racial peers, it is important to ensure that the population data used accurately reflect the genetic profile of the region from which the alleged fathers are drawn. This paper presents data on the HLA profile of Black and White residents of North Carolina. Significant differences were observed for certain antigens when the North Carolina data were compared to nationally derived population tables. Differences were observed for B7 (increase) and Bw16 (decrease) in Whites and A10 (decrease), B7 (increase) and Bw42 (decrease) in Blacks. Internal controls comparing the testing from the two participating centers showed complete agreement for White persons, but a significant difference for B5 between the two Black populations.     

Conceptualizing and Measuring Ethnic Discrimination in Health Research

This paper presents the General Ethnic Discrimination Scale, an 18-item measure of perceived ethnic discrimination that can be used in health research with any ethnic group. The 1569 participants (half college students, half community adults) completed the General Ethnic Discrimination scale and measures of cigarette smoking and of psychiatric symptoms. Results revealed that the General Ethnic Discrimination subscales model the latent construct of perceived ethnic discrimination equally well for Blacks, Latinos, Asians, and Whites. Discrimination was strongly related to psychiatric symptoms and to current cigarette smoking for ethnic minorities and Whites alike, but such relationships were stronger for ethnic minorities. Minorities who experienced frequent discrimination were 2.3 times more likely than their low-discrimination counterparts to be smokers. This 5th grade reading-level scale takes 10 min to complete and has sufficient, initial psychometric integrity for use in clinical and community health studies.     

Are there ethnic differences in sleep architecture?

The possibility of ethnic differences in sleep architecture was initially examined in conjunction with studies of sleep apnea (study 1). This possibility was then examined in another cohort of patients to determine whether the results might generalize (study 2). Polysomnography was obtained in both cohorts as part of larger protocols investigating sympathetic nervous system activity, blood pressure, and sleep. Sleep monitoring took place in an inpatient clinical research center of a university hospital. Study 1 focused on sleep apnea physiology and involved volunteers with sleep apnea who were otherwise healthy. Study 2 focused on differences in stress reactivity between American Black and White subjects and involved hypertensive and normotensive volunteers who were otherwise healthy. Analyses include 61 participants from study 1 and 35 participants from study 2. Ethnicity in both cohorts was determined by self‐report. Participants in both studies were monitored during sleep with traditional polysomnography including electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), and oximetry. In Study 1, Blacks had longer TST (P < 0.01), more REM sleep (P < 0.05), and less WASO (P < 0.05) than Whites. After controling for RDI, Blacks had longer TST and spent a smaller percentage of time in deep sleep (P < 0.05). In study 2, Blacks had longer TST and REM sleep, lower percent deep sleep, and lower percent deep sleep controling for RDI (P < 0.05). In two separate studies, Blacks had longer TST, more minutes of REM, and lower percentage deep sleep. These findings suggest possible ethnic differences in sleep architecture. Am. J. Hum. Biol. 14:321–326, 2002. © 2002 Wiley‐Liss, Inc.     

Neonatal size of low socio-economic status Black and White term births in Albany County,NYS

Birth weight has long been a focus of study by epidemiologists and human biologists, because it reflects the quality of the intrauterine environment and may be used as a predictor of future growth and development. Comparisons of Black and White neonates in the USA have consistently shown differences in birth weight. Confounding variables are a major problem in any such investigation, especially socio-economic status which is highly correlated with race in the USA. This study was distinctive in the sampling of one socio-economic stratum (low income), and the use of five anthropometric measures in addition to birth weight. The goals of this study were as follows: to determine if there were differences in body size and body composition at birth in Black and White neonates of low socio-economic status (SES), and to investigate what variables might account for any observed variability. The sample consisted of full term Black and White neonates of low SES (n = 323) born in Albany, NY (1986-1997). Birth weight, length, head and arm circumference, and subscapular and triceps skinfolds were compared. Race was determined through maternal self-identification. White neonates were significantly larger than Black neonates in birth weight, length and head circumference. Among female neonates none of the anthropometric dimensions differed between Blacks and Whites. Among male neonates, Whites were significantly larger than Blacks in birth weight, length, head and arm circumferences. Principal components analysis reduced the six anthropometric dimensions to two summary measures: body size and composition. When controlling for social and biological variables, race and sex were significant predictors of body composition, but not body size. Interpretation of results and possible causal relationships are discussed.     

Myocardial and Peripheral Vascular Responses to Behavioral Challenges and Their Stability in Black and White Americans

The purpose of this study was to assess the short term stability of myocardial and peripheral vascular responses to behavioral challenges, and to compare the response patterns of Black and White men. Blood pressure and heart rate, as well as stroke volume, cardiac output, total peripheral resistance, and systolic time interval measures derived from the impedance cardiogram were obtained in 12 Black and 12 White men. These measures were taken prior to and during an evaluative speech stressor, a mirror star tracing task, and a forehead cold pressor test presented during two laboratory sessions scheduled two weeks apart. In general, total peripheral resistance and impedance-derived baseline measures showed acceptable reproducibility (G greater than .85). With a few exceptions, adequate reliability was also demonstrated for change (delta) scores. All tasks raised blood pressure responses above resting levels. Blacks demonstrated significantly greater increases in total peripheral resistance responses across tasks. Whites but not Blacks also revealed increases above baseline in cardiac output and contractility as estimated by the Heather Index. These findings are consistent with the view that Blacks show greater vascular responsiveness than Whites across a variety of tasks, but reveal less myocardial responsiveness.     

The relation between total finger ridge-count and variability of counts from finger to finger: genetic implications of racial variation

The measure of ridge-count diversity, S/square root 10, was computed for a sample of American Whites, American Blacks and African Blacks, and the regression of S/square root 10 on total ridge-count was determined for each group. The shapes of the regression lines differed considerably. The American White curve was very similar to that obtained by Holt in an English sample, while the two Negro curves generally showed lower lower S/square root 10 values for ridge-counts over 80. The American Negro curve was found to behave like a mixture of the White and African Negro curve to a degree approximating to the fraction of White genes in their gene pool. Holt's parent-child data are used to construct a simple test of the hypothesis that that S/square root 10 reflects zygosity in total ridge-count genotypes. The preliminary results support this hypothesis.     

Parental history of hypertension and cardiovascular response to stress in black and white men

White offspring of hypertensives typically exhibit an elevated cardiovascular response to stress. Studies of Black offspring of hypertensives have been fewer, with inconsistent results. This may be due, in part, to incomplete characterizations of hemodynamic responses. This study examines cardiovascular reactivity in Black and White offspring of hypertensives with a particular focus on vascular resistance responses. A total of 62 healthy normotensive men, 41 with a parental history of hypertension (PH+: 21 Blacks, 20 Whites), and 21 without parental hypertension (PH-: 7 Blacks, 14 Whites) engaged in a series of laboratory tasks. Both Black and White PH+ participants exhibited elevated diastolic blood pressure (DBP) responses, but to different patterns of stressor tasks. Familial differences in total peripheral resistance response were also obtained for Black and White participants in a comparison across all tasks, but were particularly evident in tasks when PH+ participants had elevated DBP responses. These results suggest that a parental history of hypertension is an important moderator of cardiovascular, and in particular peripheral vascular, responses to stress in Black and White individuals. This research was supported in part by National Institutes of Health Grants HL31533 and RR00046. We thank Doris Murrell, Antonia Vincent, Nancy Pettee, and Deborah Jansen for their technical assistance.