---------------------------------------------
J Appl Physiol 1986 Nov;61(5):1758-61
Skeletal muscle characteristics in sedentary black and Caucasian
males.
Ama PF, Simoneau JA, Boulay MR, Serresse O, Theriault G, Bouchard C.
Twenty-three male Black African and 23 male Caucasian subjects,
ascertained as sedentary, participated in this study designed to
determine whether there were differences in skeletal muscle
histochemical and biochemical characteristics between racial groups.
Muscle fiber type proportions (I, IIa, and IIb), fiber areas and
activities of several enzyme markers of different energy metabolic
pathways were determined from a biopsy of the vastus lateralis.
Results indicated that Caucasians had a higher percent type I (8%, P
less than 0.01) and a lower percent type IIa (6.7%, P less than 0.05)
fiber proportions than Africans. No significant differences were
observed between the two racial groups in the type IIb fiber
proportion or in the three fiber type areas. Enzymes catalyzing
reactions in phosphagenic [creatine kinase (CK)] and glycolytic
[hexokinase (HK), phosphofructokinase (PFK), and lactate
dehydrogenase (LDH)] metabolic pathways had significantly higher
activities (about 30-40%) in the Black African group than in the
Caucasian group (P less than 0.01). No significant difference was
noted in the activities of oxidative enzymes [malate dehydrogenase
(MDH), oxoglutarate dehydrogenase (OGDH), and 3-hydroxyacyl-CoA
dehydrogenase (HADH)]. Consequently, the PFK/OGDH ratio was
significantly elevated in Africans (P less than 0.05). The racial
differences observed between Africans and Caucasians in fiber type
proportion and enzyme activities of the phosphagenic and glycolytic
metabolic pathways may well result from inherited variation. These
data suggest that sedentary male Black individuals are, in terms of
skeletal muscle characteristics, well endowed for sport events of
short duration.
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2. ACE differences:
-----------------------------------------------
Am J Med Sci 2000 Jul;320(1):18-23
Elevated mortality rates from circulatory disease in African American
men and women of Los Angeles County, California--a possible genetic
susceptibility?
Henderson SO, Coetzee GA, Ross RK, Yu MC, Henderson BE.
OBJECTIVE: Reports of higher mortality in African Americans have
often focused on socioeconomic differences. Such differences do not
explain the excess mortality in African Americans compared with
Hispanics in Los Angeles County. We suggest the existence of genetic
factors to explain at least some of the differences in mortality
risk. METHODS: We compared the mortality rates from circulatory
diseases in African American and Hispanic adults of Los Angeles
County for 1988 to 1992 with the frequency of the angiotensin-
converting enzyme (ACE) genotype. RESULTS: African American adults 45
to 74 years old had a 2-fold higher overall mortality rate than
Hispanics. The largest differences were seen for hypertensive disease
and cardiomyopathy in men; the most striking differences were seen in
the youngest age group. Rates were lower in women than in men, but
African American women also showed substantial excess compared with
Hispanics. ACE genotype also showed a significant difference between
the Hispanic and African American population; the latter had a
significantly higher prevalence of the DD genotype, which is
associated with a higher level of circulating enzyme, and lower
prevalence of the II genotype, which is associated with a lower
enzyme level.
CONCLUSION: African American adults aged 45 to 74 years
in Los Angeles County have a substantial excess mortality from
hypertensive diseases compared with a similar Hispanic population.
The frequency of the ACE DD genotype was higher in African Americans
than in Hispanics. These studies may indirectly support the
possibility of a genetic contribution to the excess hypertensive
disease mortality in African Americans.
-----------------------------------------------
3. Body and Bone Mass Differences:
-----------------------------------------------
Ethn Health 1996 Dec;1(4):337-47
Ethnic differences in body composition and their relation to health
and disease in women.
Gasperino J.
Differences in body composition between black and white women have
been well established. Black women have more bone and muscle mass,
but less fat, as a percentage of body weight, than white women, after
controlling for ethnic differences in age, body weight, and height.
In addition, black women have more upper-body fat than white women.
These ethnic differences in body composition appear to be associated
with disease risk in women. The greater skeletal and muscle mass in
black compared to white women appears to protect them from
osteoporosis. The relationship between fat distribution and
cardiovascular disease also appears to be influenced by ethnicity.
This review has two purposes: (1) To examine previous research
investigating ethnic differences in body composition between black
and white women; and (2) To demonstrate the relationship between body
composition and disease in women as a function of ethnicity.
-----------------------------------------------
Am J Clin Nutr 2000 Jun;71(6):1392-402
Measures of body composition in blacks and whites: a comparative
review.
Wagner DR, Heyward VH.
Biological differences exist in the body composition of blacks and
whites. We reviewed literature on the differences and similarities
between the 2 races relative to fat-free body mass (water, mineral,
and protein), fat patterning, and body dimensions and proportions. In
general, blacks have a greater bone mineral density and body protein
content than do whites, resulting in a greater fat-free body density.
Additionally, there are racial differences in the distribution of
subcutaneous fat and the length of the limbs relative to the trunk.
The possibility that these differences are a result of ethnicity
rather than of race is also examined. Because most equations that
predict relative body fat were derived from predominantly white
samples, biological variation between the races in these body-
composition indexes has practical significance. Systematic error can
result in the inaccurate estimation of the relative body fat of
blacks, and therefore of definitions of obesity, if these inherent
differences are ignored.
J Appl Physiol 1984 Jun;56(6):1647-9
Density of lean body mass is greater in blacks than in whites.
Schutte JE, Townsend EJ, Hugg J, Shoup RF, Malina RM, Blomqvist CG.
Previous studies have reported that Blacks have 10-20% more bone
mineral than Whites of the same height. Theoretically, this should
mean that the lean body mass of Blacks is denser than that of Whites,
such that formulas for calculating lean body mass from density in
Whites will overestimate the lean body mass (and thus underestimate
fatness) in Blacks. To determine if the lean body mass of Blacks is
indeed denser than that of Whites, we measured density, total body
water, and anthropometric dimensions in 19 white and 15 black male
college students. The black and white cohorts were nearly identical
in height, weight, and total body water. Among the Whites there was
no significant difference between the observed density and that
predicted from anthropometry, nor were there any significant
differences between the dimensions of body composition calculated
from total body water and from observed density. Among the Blacks,
however, the observed density was significantly greater than that
predicted from anthropometry, and the lean body mass calculated from
observed density was significantly greater than that calculated from
total body water. These results are consistent with the hypothesis
that the lean body mass of the Blacks is denser than that of the
Whites. Separate formulas should therefore be used for converting
density to body composition. Based on our data, the correct formula
for Blacks is: %fat = 100 X [(4.374/density) - 3.928]. This formula
indicates a lean body density of 1.113 g/cm3 in Blacks compared with
1.100 in Whites.
-------------------------------------------------
4. Hormonal differences:
-------------------------------------------------
J Clin Endocrinol Metab 1995 Aug;80(8):2291-7
Greater secretion of growth hormone in black than in white men:
possible factor in greater bone mineral density--a clinical research
center study.
Wright NM, Renault J, Willi S, Veldhuis JD, Pandey JP, Gordon L, Key
LL, Bell NH.
To determine why blacks have a higher bone mineral density (BMD) and
lower incidence of osteoporosis and fractures than whites, we
investigated whether the secretion of GH is higher in black than in
white men. Measurements of GH were obtained at 20-min intervals over
24 h and analyzed by deconvolution. BMD was determined by dual energy
x-ray absorptiometry in 16 normal black and 17 normal white men, aged
20-40 yr. The 24-h integrated GH concentration 942 +/- 174 vs. 602 +/-
104 micrograms/L; P = 0.0495) and GH secretory burst amplitude (0.499
+/- 0.163 vs. 0.169 +/- 0.027 micrograms/L.min; P = 0.0482) were
higher in black than in white men. GH burst frequency, half-duration,
mass, and half-life were not different in the 2 groups. The serum 17
beta-estradiol level (162 +/- 12 vs. 108 +/- 11 pmol/L; P = 0.0011)
was higher, and the serum insulin-like growth factor-binding protein
3 level (2.2 +/- 0.1 vs. 2.8 +/- 0.1 microgram/mL; P = 0.0001) was
lower in black than in white men. BMD values for total body (1.22 +/-
0.02 vs. 1.14 +/- 0.02 g/cm2; P = 0.0041), forearm (0.69 +/- 0.01 vs.
0.66 +/- 0.01 g/cm2; P = 0.0211), trochanter (0.91 +/- 0.03 vs. 0.77
+/- 0.03 g/cm2; P = 0.0003), and femoral neck (1.08 +/- 0.03 vs. 0.93
+/- 0.03 g/cm2; P = 0.0007) were higher in black than in white men.
Thus, serum 17 beta-estradiol level, GH secretion, and BMD values for
the total body, forearm, trochanter, and femoral neck are greater in
black than in white men. As estrogen is known to increase GH
secretion and GH to increase bone mass, increases in circulating 17
beta-estradiol may contribute to the higher GH secretion and bone
mass in black men.
----------------------------------------------
J Natl Cancer Inst 1986 Jan;76(1):45-8
Serum testosterone levels in healthy young black and white men.
Ross R, Bernstein L, Judd H, Hanisch R, Pike M, Henderson B.
Blacks in the United States have the highest prostate cancer rate in
the world and nearly twice that of whites in the United States. The
2:1 black-to-white ratio in prostate cancer rates is already apparent
at age 45 years, the age at which the earliest prostate cancer cases
occur. This finding suggests that the factor(s) responsible for the
difference in rates occurs, or first occurs, early in life.
Testosterone has been hypothesized to play a role in the etiology of
prostate cancer, because testosterone and its metabolite,
dihydrotestosterone, are the principal trophic hormones that regulate
growth and function of epithelial prostate tissue. This report gives
the results of assays of circulating steroid hormone levels in white
and black college students in Los Angeles, CA. Mean testosterone
levels in blacks were 19% higher than in whites, and free
testosterone levels were 21% higher. Both these differences were
statistically significant. Adjustment by analysis of covariance for
time of sampling, age, weight, alcohol use, cigarette smoking, and
use of prescription drugs somewhat reduced the differences. After
these adjustments were made, blacks had a 15% higher testosterone
level and a 13% higher free testosterone level. A 15% difference in
circulating testosterone levels could readily explain a twofold
difference in prostate cancer risk.
----------------------------------------------
5. Endurance ability and East African Heritage:
----------------------------------------------
J Appl Physiol 1999 Mar;86(3):915-23
African runners exhibit greater fatigue resistance, lower lactate
accumulation, and higher oxidative enzyme activity.
Weston AR, Karamizrak O, Smith A, Noakes TD, Myburgh KH.
Nine African and eight Caucasian 10-km runners resident at sea level
volunteered. Maximal O2 consumption and peak treadmill velocity (PTV)
were measured by using a progressive test, and fatigue resistance
[time to fatigue (TTF)] was measured by using a newly developed high-
intensity running test: 5 min at 72, 80, and 88% of individual PTV
followed by 92% PTV to exhaustion. Skeletal muscle enzyme activities
were determined in 12 runners and 12 sedentary control subjects. In a
comparison of African and Caucasian runners, mean 10-km race time,
maximal O2 consumption, and PTV were similar. In African runners, TTF
was 21% longer (P < 0.01), plasma lactate accumulation after 5 min at
88% PTV was 38% lower (P < 0.05), and citrate synthase activity was
50% higher (27.9 +/- 7.5 vs. 18.6 +/- 2.1 micromol. g wet wt-1. min-
1, P = 0.02). Africans accumulated lactate at a slower rate with
increasing exercise intensity (P < 0.05). Among the entire group of
runners, a higher citrate synthase activity was associated with a
longer TTF (r = 0.70, P < 0.05), a lower plasma lactate accumulation
(r = -0.73, P = 0.01), and a lower respiratory exchange ratio (r = -
0.63, P < 0.05). We conclude that the African and Caucasian runners
in the present study differed with respect to oxidative enzyme
activity, rate of lactate accumulation, and their ability to sustain
high-intensity endurance exercise.
The full article can be found at:
-----------------------------------------------
J Appl Physiol 1993 Oct;75(4):1822-7
Superior fatigue resistance of elite black South African distance
runners.
Coetzer P, Noakes TD, Sanders B, Lambert MI, Bosch AN, Wiggins T,
Dennis SC.
Black athletes currently dominate long-distance running events in
South Africa. In an attempt to explain an apparently superior running
ability of black South African athletes at distances > 3 km, we
compared physiological measurements in the fastest 9 white and 11
black South African middle-to long-distance runners. Whereas both
groups ran at a similar percentage of maximal O2 uptake (%VO2max)
over 1.65-5 km, the %VO2max sustained by black athletes was greater
than that of white athletes at distances > 5 km (P < 0.001). Although
both groups had similar training volumes, black athletes reported
that they completed more exercise at > 80% VO2max (36 +/- 18 vs. 14
+/- 7%: P < 0.005). When corrections were made for the black
athletes' smaller body mass, their superior ability to sustain a high
%VO2max could not be explained by any differences in VO2max, maximal
ventilation, or submaximal running economy. Superior distance running
performance of the black athletes was not due to a greater (+/- 50%)
percentage of type I fibers but was associated with lower blood
lactate concentrations during exercise. Time to fatigue during
repetitive isometric muscle contractions was also longer in black
runners (169 +/- 65 vs. 97 +/- 69 s; P < 0.05), but whether this
observation explains the superior endurance or was due to the lower
peak muscle strength (46.3 +/- 10.3 vs. 67.5 +/- 18.0 Nm/l lean thigh
volume; P < 0.01) remains to be established.
Eur J Appl Physiol Occup Physiol 1990;61(1-2):68-72
Physiological differences between black and white runners during a
treadmill marathon.
Bosch AN, Goslin BR, Noakes TD, Dennis SC.
To determine why black distance runners currently out-perform white
distance runners in South Africa, we measured maximum oxygen
consumption (VO2max), maximum workload during a VO2max test (Lmax),
ventilation threshold (VThr), running economy, inspiratory
ventilation (VI), tidal volume (VT), breathing frequency (f) and
respiratory exchange ratio (RER) in sub-elite black and white runners
matched for best standard 42.2 km marathon times. During maximal
treadmill testing, the black runners achieved a significantly lower
(P less than 0.05) Lmax (17 km h-1, 2% grade, vs 17 km h-1, 4% grade)
and VI max (6.21 vs 6.82 l kg-2/3 min-1), which was the result of a
lower VT (101 vs 119 ml kg-2/3 breath-1) as fmax was the same in both
groups. The lower VT in the black runners was probably due to their
smaller body size. The VThr occurred at a higher percentage VO2max in
black than in white runners (82.7%, SD 7.7% vs 75.6%, SD 6.2%
respectively) but there were no differences in the VO2max. However,
during a 42.2-km marathon run on a treadmill, the black athletes ran
at the higher percentage VO2max (76%, SD 7.9% vs 68%, SD 5.3%), RER
(0.96, SD 0.07 vs 0.91, SD 0.04) and f (56 breaths min-1, SD 11 vs 47
breaths min-1, SD 10), and at lower VT (78 ml kg-2/3 breath-1, SD 15
vs 85 ml kg-2/3 breath-1, SD 19). The combination of higher f and
lower VT resulted in an identical VI.
--------------------------------------------------
Scand J Med Sci Sports 1995 Aug;5(4):209-21
Aerobic exercise capacity at sea level and at altitude in Kenyan
boys, junior and senior runners compared with Scandinavian runners.
Saltin B, Larsen H, Terrados N, Bangsbo J, Bak T, Kim CK, Svedenhag
J, Rolf CJ.
The aim of this study was to characterize Kenyan runners in regard to
their oxygen uptake and blood and ammonia responses when running.
Untrained Kenyan boys (14.2 +/- 0.2 years) and Scandinavian runners
were included for comparison. The studies were performed at altitude
(approximately 2.000 m.a.s.l.) and, for several Kenyan and
Scandinavian runners, at sea level as well.
At altitude sedentary adolescent Kenyan boys had a mean maximal oxygen uptake (VO2max) of
47 (44-51) ml.kg-1.min-1, whereas similarly aged boys regularly
walking or running but not training for competition reached above 62
(58-71) ml.kg-1.min-1 in VO2max. Kenyan runners in active training
had 68 +/- 1.4 ml.kg-1.min-1 at altitude and 79.9 +/- 1.4 ml.kg-1.min-
1 at sea level, with individuals reaching 85 ml.kg-1.min-1. The best
Scandinavian runners were not significantly different from the Kenyan
runners in VO2max both at altitude and at sea level, but none of the
Scandinavians reached as high individual values as observed for some
Kenyan runners. The running efficiency, determined as the oxygen cost
at a given running speed, was less in the Kenyan runners, and the
difference became more pronounced when body weight was expressed in
ml.kg-0.75 min-1. Blood lactate concentration was in general lower in
the Kenyan than in the Scandinavian runners, and the Kenyans also had
extremely low ammonia accumulation in the blood even at very high
exercise intensities. It is concluded that it is the physical
activity during childhood, combined with intense training as
teenagers that brings about the high VO2max observed in some Kenyan
runners. Their high aerobic capacity, as well as their good running
economy, makes them such superior runners. In addition, their low
blood lactate and ammonia accumulation in blood when running may also
be contributing factors.
Scand J Med Sci Sports 1995 Aug;5(4):222-30
Morphology, enzyme activities and buffer capacity in leg muscles of
Kenyan and Scandinavian runners.
Saltin B, Kim CK, Terrados N, Larsen H, Svedenhag J, Rolf CJ.
The study comprises data on 12 Scandinavian runners who had either
trained for two weeks in Kenya (n = 6; approximately 2000 meters
above sea level (m.a.s.l.)) or in Portugal (n = 6; sea level (s.l.))
and on 13 Kenyan runners (9 junior and 4 senior) living and training
at approximately 2000 m.a.s.l. Muscle biopsies were taken before and
after the training camps in the Scandinavian runners and once on the
Kenyan runners from the vastus lateralis (v.l.) and the gastrocnemius
muscles.
Muscle fiber size and composition were similar in the
various groups (4.6-5.1 X 10(3) microns2; ST approximately 60-70%;
FTa 30-40%; FTb < 6.0%) with a tendency for some more (approximately
5%) FTa fibers in the gastrocnemius muscle. Mean number of
capillaries in v.l. varies between 405-493 cap.(mm2)-1, 2.0-2.7
cap.fiber-1, and 4.4-6.2 cap around the various fiber types, with the
Kenyan seniors having the highest and the Kenyan juniors the lowest
values. All runners had 10-20% more capillaries in their
gastrocnemius muscle. Similar levels for citrate synthase (CS)
activity were found in the v.l. of the Kenyan seniors and
Scandinavian runners, whereas the Kenyan juniors were 10-15% lower.
The 3- hydroxyacyl-CoA-dehydrogenase (HAD) activity was 20% higher in
the Kenyan than in the Scandinavian runners. In the gastrocnemius
muscle, both enzyme activities were 20-50% higher in Scandinavian and
Kenyan runners. The ratio for lactate dehydrogenase (LDH) isoform1-2
and isoform4-5 was increased when training at altitude due to a
lowering of LDH4-5 and became close to what was observed in the
Kenyan runners.
----------------------------------------------------------------------------
Estradiol and testosterone effects on lipids in black and white boys aged 10 to 15 years.
Morrison JA, Sprecher DL, Biro FM, Apperson-Hansen C, Lucky AW, DiPaola LM.
Dermatology, University of Cincinnati College of Medicine and Children's Hospital Medical Center, OH 45229, USA.
Previous studies of lipids in adolescent males have shown greater increases in triglycerides and decreases in high-density lipoprotein cholesterol (HDL-C) in white boys compared with black boys, significant correlations between sex hormones and lipids, and complex body mass index (BMI) hormone-lipid associations. Within this frame of reference, we assessed race, BMI, and sex hormones as predictors of lipid parameters in 536 black and white boys recruited from area schools. Black boys were more advanced in puberty than white boys. After adjusting for pubertal stage, estradiol (E2) levels were higher in black boys but free testosterone (T) levels did not differ. Age, pubertal stage, race, BMI, free T, and E2 were entered as explanatory variables for lipids in backward stepwise regression analyses. The BMI and race were retained in every model. Black boys had lower triglycerides and apolipoprotein B (apo B) and higher HDL-C. E2 was inversely associated with total cholesterol (TC), triglycerides, low-density lipoprotein cholesterol (LDL-C), apo B, and the LDL-C/HDL-C ratio. Free T was inversely associated with HDL-C and positively associated with apo B. Given the increases in free T and E2 during adolescence and the association of these hormones with both atherogenic and protective lipid parameters, racial differences in E2 could contribute to the more atherogenic lipid profile found in white boys after puberty.
PMID: 11016891 [PubMed - indexed for MEDLINE]
----------------------------------------------
---------------------------------------------------
Dementia and race: are there differences between African Americans and Caucasians?
Froehlich TE, Bogardus ST Jr, Inouye SK.
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06504, USA.
This study provides an overview of racial differences in etiology and prevalence of dementia. Preliminary findings indicate that the clinical and molecular etiologies of dementia differ between races. African Americans have a higher prevalence of vascular dementia and a lower prevalence of Parkinsonian dementia than do Caucasians. The genetic etiologies of Alzheimer's-type dementia appear to differ between African Americans and Caucasians. The variations in dementia etiologies and in cognitive testing accuracy between races suggests the urgent need to develop racially appropriate cognitive assessment methods and to develop preventive and treatment etiologies differently according to racial background of individual patients.
Publication Types:
· Review
· Review literature
-------------------------------------------
Racial differences in the sums of skinfolds and percentage of body fat estimated from impedance in black and white girls, 9 to 19 years of age: the National Heart, Lung, and Blood Institute Growth and Health Study.
Morrison JA, Barton BA, Obarzanek E, Crawford PB, Guo SS, Schreiber GB.
Division of Cardiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA. morrj2@chmcc.org
OBJECTIVES: This National Heart, Lung, and Blood Institute Growth and Health Study report assesses racial differences in fat patterning in black and white girls ages 9 to 19 years, comparing the sum of triceps and subscapular skinfolds (SSFs) and percentage of body fat (%BF) from impedance as two indices of adiposity. It is hypothesized that racial differences in fat patterning manifest during puberty. RESEARCH METHODS AND PROCEDURES: SSF and %BF were measured annually. Racial differences in SSF and %BF were evaluated by age. Associations between %BF and SSF were evaluated using the Pearson's correlations coefficient. Classification agreement was evaluated using the kappa-statistic. Effects of pubertal stage and race on classification agreement were examined using multivariate models. RESULTS: White girls had a greater mean %BF at 9 to 12 years of age; black girls had a greater %BF thereafter. Black girls had a greater mean SSF at every age. The correlation coefficient between SSF and %BF was 0.79, and there was good agreement between %BF and SSF in separating high (>85th percentile) from not high (kappa = 0.60 for whites and 0.66 for blacks). SSF associated more with %BF in prepuberty and early puberty than in late puberty. DISCUSSION: Despite good correlations between %BF and SSF, the two methods indicate different fat patterns in black and white girls.
PMID: 11346671 [PubMed - in process]
The heritability of intelligence in Japan.
Lynn R, Hattori K.
University of Ulster, Coleraine, County Londonderry, Northern Ireland.
Japanese data for 543 monozygotic (MZ) twins and 134 dizygotic (DZ) twins tested for intelligence at the age of 12 give correlation coefficients of .782 and .491, respectively, indicating a heritability of .582. Heavier twins at birth have significantly higher IQs at the age of 12, suggesting that prenatal nutrition exerts a significant effect on intelligence.
PMID: 2256894 [PubMed - indexed for MEDLINE]
Behav Res Ther 1993 Jul;31(6):569-74 Related Articles, Books
Is optimism heritable? A study of twins.
Schulman P, Keith D, Seligman ME.
Department of Psychology, University of Pennsylvania, Philadelphia 19104-6196.
Is optimism heritable? We gave the Attributional Style Questionnaire (ASQ), a measure of optimism, to 115 monozygotic twin pairs (MZ) and 27 dizygotic twin pairs (DZ). The intraclass correlations of the ASQ scores were 0.48 for MZ twins (P < 0.0001) and 0 for DZ twins. Though the sample size of DZ twins is small, these results suggest that there may be a substantial genetic effect on optimism. We speculate, however, that the mechanism for the transmission of this, and other complex personality traits, may be highly indirect.
Acta Physiol Scand 2002 Jul;175(3):183-7
Comparison of viscoelastic characteristics in triceps surae between Black
and White athletes.
Fukashiro S, Abe T, Shibayama A, Brechue WF.
The purpose of the present study was to investigate race differences in viscoelastic characteristics of triceps surae muscle group. Black and white college sprint type athletes (n=44) participated in this study. Viscoelastic properties were assessed using the free vibration technique: subjects sat with their forefeet on the edge of a force-plate (Kistler, Switzerland) and support a frame loaded with weights (0-40 kg) on the knees. Oscillations of the triceps surae and Achilles tendon system were initiated with a hand-held hammer by tapping the weight load. Oscillations occur at frequencies of 3-6
Hz and were slightly damped. The damped oscillations in conjunction with the equation of motion of a damped mass-spring model were used to calculate the viscosity of muscle (b), and the elasticity of muscle fibres (kd) and tendon (kt) in each subject.
There were little significant differences in most of physical characteristic variables between black and white athletes. Black athletes have significantly greater muscle viscosity and elasticity than white athletes while tendon elasticity is equivalent. Thus, muscle stiffness is greater among black athletes. Greater muscle stiffness could contribute to greater sprint/jump performance among black athletes, compared with white athletes, through alteration of foot/ground contact and take-off phases during sprinting/jumping.
___________________
Racial differences in androgen receptor protein expression in men with clinically localized prostate cancer.
Gaston KE, Kim D, Singh S, Ford OH 3rd, Mohler JL.
Division of Urology, Department of Surgery, University of North Carolina, Chapel Hill, NC 27599, USA.
PURPOSE: Black American men experience disproportionate mortality from prostate cancer (CaP) compared with white American men. Differences in outcome may stem from differences within the androgen axis. Since serum testosterone levels appear to be similar by race in men with CaP, we measured and compared androgen receptor (AR) protein expression in malignant and benign prostate tissue from black and white men who underwent radical prostatectomy for clinically localized CaP. MATERIALS AND METHODS: Archived radical prostatectomy specimens obtained from 25 white and 25 black men had AR protein antigen retrieved and immunostained. AR protein expression from CaP and benign tissue was assessed by 2 methods. Automated digital color video image analysis was used to measure the percent area immunostained for AR protein and the intensity of expression (mean optical density). Visual scoring was performed to compare results with automated values. RESULTS: In black compared with white men malignant nuclei were 27% more likely to immunostain for AR (p = 0.005) and in immunopositive nuclei AR protein expression was 81% greater (p = 0.002). Visual scoring of malignant nuclei revealed that AR immunostaining was significantly increased in black vs white men (171 +/- 40 vs 149 +/- 37, p = 0.048). In immunopositive benign nuclei AR protein expression was 22% greater in black than in white men (p = 0.027). Visual scoring of benign nuclei revealed 20% increased immunostaining in black vs white men, although this difference did not attain statistical significance (p = 0.065). Racial differences in AR protein expression were not explained by age, pathological grade or stage, although serum prostate specific antigen levels were higher in black men (9.7 +/- 7.5 vs 15.5 +/- 12.2 ng/ml, p = 0.049). CONCLUSIONS: AR protein expression was 22% higher in the benign prostate and 81% higher in the CaP of black African compared with white men. CaP may occur at a younger age and progress more rapidly in black than in white men due to racial differences in androgenic stimulation of the prostate.
_____
Relationships between prostate-specific antigen and prostate volume in black and white men with benign prostate biopsies.
Fowler JE Jr, Bigler SA, Kilambi NK, Land SA.
Department of Pathology, University of Mississippi School of Medicine, Veterans Affairs Medical Center, Jackson, USA.
OBJECTIVES: To determine whether the higher age-adjusted serum prostate-specific antigen (PSA) levels in black compared with white men with no clinical evidence of prostate cancer reflect racial differences in relationships between PSA and prostate volume. METHODS: The age, PSA, findings on digital rectal examination (DRE), prostate volume, and PSA density were assessed prospectively in 810 consecutive, evaluable men who underwent prostate biopsy for suspected cancer but who had benign histologic findings. RESULTS: Among the black and white patients, there were significant differences in age (mean 67.2 +/- 8.1 and 65.9 +/- 7.7 years, respectively, P = 0.02), PSA (median 4.7 and 3.9 ng/mL, respectively, P <0.0001), prostate volume (median 41 and 36 mL, respectively, P = 0.004), and PSA density (median 0.11 and 0.08 ng/mL/mL, respectively, P = 0.005). Multiple linear regression analyses showed that black race was significantly associated with increased prostate volume when controlled for age (P = 0.02), with increased PSA when controlled for prostate volume and age (P = 0.002), and with increased PSA density when controlled for age (P = 0.007). When controlled for prostate volume, PSA was not significantly different in black and white men 50 to 59 years old but was significantly greater in black men 60 to 69 and 70 to 79 years old (P = 0.02 and 0.002, respectively). CONCLUSIONS: On a volume/volume basis, the benign prostatic tissue of black men appears to contribute more PSA to the circulating blood than does the benign prostatic tissue of white men, and the difference increases with advancing age. These phenomena provide a reasonable explanation for the age-adjusted racial differences in the PSA of men with no clinical evidence of cancer.
_____
Racial differences in clinically localized prostate cancers of black and white men.
deVere White RW, Deitch AD, Jackson AG, Gandour-Edwards R, Marshalleck J, Soares SE, Toscano SN, Lunetta JM, Stewart SL.
Department of Urology, University of California, Davis, USA.
PURPOSE: Tumor grade, deoxyribonucleic acid (DNA) ploidy, proliferation, p53 and bcl-2 expression were examined in clinically localized prostate cancers of black and white American men to learn whether these features showed racial differences. MATERIALS AND METHODS: A total of 117 prostate cancers (43 black and 74 white patients) obtained at radical prostatectomy for clinically localized disease were assigned Gleason scores by a single pathologist. Enzymatically dissociated nuclei from archival prostate cancers were examined by DNA flow cytometry using propidium iodide staining and the multicycle program to remove debris and sliced nuclei and to perform cell cycle analysis. For immunostaining after microwave antigen retrieval we used a DO-1/DO-7 monoclonal antibody cocktail for p53 and the clone 124 antibody for bcl-2. RESULTS: Significantly more black than white men had Gleason score 7 tumors. The DNA ploidy distribution of Gleason 6 or less tumors was similar for both races. As anticipated, the ploidy distribution of higher grade prostate cancer in white men was more abnormal but, unexpectedly, this was not found for higher grade prostate cancer in black men. No significant racial differences were found in S phase fractions, p53 or bcl-2 immunopositivity. However, for prostate cancer in black men there was a significant association between bcl-2 immunopositivity and higher S-phase fractions. CONCLUSIONS: The aggressive prostate cancers of black men may be characterized by the 2 features of high proliferation and a block to programmed cell death.
Percent free prostate specific antigen and cancer detection in black and white men with total prostate specific antigen 2.5 to 9.9 ng./ml.
Fowler JE Jr, Sanders J, Bigler SA, Rigdon J, Kilambi NK, Land SA.
Division of Urology and Department of Pathology, University of Mississippi School of Medicine, Jackson, Mississippi, USA.
PURPOSE: The ratio of free-to-total prostate specific antigen (PSA), or percent free PSA, is a useful adjunct to total PSA for estimating the risk of prostate cancer when total PSA is 2.5 to 9.9 ng./ml. Relationships between cancer detection and total PSA are influenced by race but to our knowledge relationships between cancer detection and percent free PSA have not been studied. MATERIALS AND METHODS: A total of 222 black and 298 white consecutive and evaluable men with total PSA 2.5 to 9.9 ng./ml. underwent prostate biopsy for suspected cancer at a Veterans Affairs Medical Center. Clinical measurements included digital rectal examination, total and free serum PSA, prostate volume, PSA density and Gleason score of malignant biopsy specimens. RESULTS: Median percent free PSA was 14.1 (range 3.6 to 49.2) in 201 men with prostate cancer and 21.9 (range 5.7 to 83.3) in 319 without detectable cancer (p <0.0001). Significant racial differences in demographic characteristics and clinical measurements were limited to total PSA, which was higher in black men (p = 0.03). Cancer was detected in 156 black (47%) and 206 white (33%) men (p = 0.001). Areas under receiver operating characteristics curves for percent free PSA and total PSA were 0.66 and 0.58, respectively, for black men (p = 0.15), and 0.76 and 0.58, respectively, for white men (p <0.00001). Percent free PSA was 35.2 in black men and 29.2 in white men, and specificity was 9.1% and 28.7%, respectively, when sensitivity for percent free PSA was set at 95%. Of 156 black and 206 white men with percent free PSA less than 25, 83 (53%) and 85 (41%), respectively, had detectable cancer (p = 0.03). Of 66 black and 92 white men with percent free PSA 25 or greater 21 (32%) and 12 (13%), respectively, had detectable cancer (p = 0.005). CONCLUSIONS: Our study demonstrates racial differences in relationships between percent free PSA and cancer detection in men with suspected prostatic carcinoma and total PSA 2.5 to 9.9 ng./ml. Clinical application of the commonly used percent free PSA cutoff of less than 25 to determine the advisability of prostate biopsy may lead to under diagnosis of early stage prostate cancer in black men, who are at greater risk of morbidity and mortality from disease than white men.
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Are there gender and race differences in cellular immunity patterns over age in infected and uninfected children born to HIV-infected women?
European Collaborative Study.
This study investigated whether age-related patterns of immunologic markers in 1488 uninfected (9789 measurements) and 186 infected (3414 measurements) children differed by gender and race. CD4+, CD8+, and absolute lymphocytes by HIV infection status, gender, and race were assessed using linear mixed-effects natural cubic spline models, allowing for prematurity and maternal CD4+ cell count. In uninfected children, levels of all 3 markers peaked twice in the first few months of life, declining to adult levels by around 8 years of age; uninfected boys and uninfected black children had significantly reduced CD4+ and absolute lymphocyte counts; the gender difference was especially pronounced in black children. Infected children had substantially lower levels and distinctly different patterns; with, e.g., by age 6 months CD4+ cell counts nearly 1200 per mm3 lower than in uninfected infants. Levels also significantly differed by gender and race for infected children, although for gender in the opposite direction. The gender and race differences in CD4+ levels were not explained by a general lymphocytosis nor were they confounded by treatment. These substantial differences in immunologic markers may reflect underlying genetic influence on the cellular immune system and may have implications for clinical decisions about therapeutic management
Racial differences in outcome in the Multicenter UnSustained Tachycardia Trial (MUSTT): a comparison of whites versus blacks.
Russo AM, Hafley GE, Lee KL, Stamato NJ, Lehmann MH, Page RL, Kus T, Buxton AE; Multicenter UnSustained Tachycardia Trial Investigators.
University of Pennsylvania Health System, Presbyterian Medical Center, Philadelphia, PA 19104, USA. andrea_russo@uphs.upenn.edu
BACKGROUND: The Multicenter UnSustained Tachycardia Trial (MUSTT) demonstrated the benefit of implantable cardioverter-defibrillators (ICDs) in patients with coronary disease, asymptomatic nonsustained ventricular tachycardia, and reduced left ventricular function. Previous studies have shown racial differences in risk of sudden death in patients with ischemic heart disease. METHODS AND RESULTS: We analyzed the influence of race on results of MUSTT. Whites were more likely to have prior revascularization and inducible, randomizable sustained ventricular arrhythmias and less likely to have left ventricular hypertrophy than were blacks. Compared with blacks, whites randomly assigned to electrophysiologically (EP)-guided therapy had a lower risk of arrhythmic death/cardiac arrest (adjusted P=0.003) and lower total mortality rates (adjusted P=0.051). In contrast, there was no racial difference in the risk of arrhythmic death/cardiac arrest among patients randomly assigned to no EP-guided therapy (adjusted P=0.477). Among whites, EP-guided therapy resulted in a survival benefit compared with no EP-guided therapy. However, survival of blacks randomly assigned to no EP-guided therapy was better than blacks receiving EP-guided therapy. This difference is partially explained by a higher ICD implantation rate in whites versus blacks (50% versus 28%, P=0.034). Whites were more likely to remain inducible after serial EP-guided drug testing (67% versus 42%, P=0.011), making them more likely to become eligible for ICDs. CONCLUSIONS: The outcome in this trial and the benefit of EP-guided therapy appeared to be influenced by race. In addition to differences in ICD implantation rates, differences in arrhythmic substrates and proarrhythmic responses to antiarrhythmic drugs may have influenced outcome.
Publication Types:
· Clinical Trial
· Multicenter Study
· Randomized Controlled Trial
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Total body potassium differs by sex and race across the adult age span.
He Q, Heo M, Heshka S, Wang J, Pierson RN Jr, Albu J, Wang Z, Heymsfield SB, Gallagher D.
Obesity Research Center, St Luke's-Roosevelt Hospital, and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY 1025, USA.
BACKGROUND: Total body potassium (TBK) is an index of fat-free mass. Data describing changes in TBK in African American, Asian, or Hispanic populations have not been reported. OBJECTIVE: The aim was to investigate possible sex and racial differences in TBK in adults over an age range of 70 y. DESIGN: The study used longitudinal and cross-sectional data collected in a body-composition unit from 973 men and 1368 women of African American, Asian, white, and Hispanic race-ethnicity. Random coefficient models in which baseline weight and height were taken into account were applied to estimate sex-specific changes in TBK among the 4 racial-ethnic groups. RESULTS: The ages of 30 and 31 y were identified for women and men, respectively, as the cutoffs after which TBK began to decline. Both sexes had similar racial-ethnic patterns for expected mean TBK at the age cutoffs: African Americans had the highest value, followed by whites, Hispanics, and Asians. After the age cutoffs, the decline in TBK differed by race and sex. In women, African Americans showed the most rapid decline, whereas Asians had the lowest. In men, Hispanics had the most rapid decline in TBK, followed by African Americans, whites, and Asians. CONCLUSION: Significant sex and racial differences exist in the rate of change in TBK with age. Further studies are needed to explore the associations of declining TBK with health risks.
Genetic diversity of the alpha-1-antitrypsin gene in Africans identified using a novel genotyping assay.
Hayes VM.
Genetics Laboratory, Department of Urology, University of Stellenbosch, Faculty of Health Sciences, Tygerberg, South Africa. v.hayes@garvan.org.au
The highly polymorphic human alpha-1-antitrypsin (AAT) gene, more recently named SERPINA1, codes for the most abundant circulating plasma serine protease inhibitor, protease inhibitor 1 (PI). Most studies determining AAT haplotype frequencies have been restricted first by the limited accuracy of the phenotypic method used and secondly by the analysis of predominantly Caucasian populations. Limited studies have been performed on African-based populations. Here a new comprehensive assay for genotyping the entire coding region, including splice junctions, of the AAT gene was designed. This assay, based on denaturing gradient gel electrophoresis (DGGE), allows for the complete analysis of a single individual in two lanes on a gel. Application of the assay resulted in the identification of nine known AAT variants as well as 13 novel sequence variants, five of which are single nucleotide polymorphisms (SNPs), occurring exclusively in the African-based populations. This is the first comprehensive analysis of the genetic diversity of the AAT gene in a cohort from sub-Saharan Africa.
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Population genetics of alpha-1-antitrypsin polymorphism in US whites, US blacks and African blacks.
DeCroo S, Kamboh MI, Ferrell RE.
Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pa.
An isoelectric focusing (IEF) procedure in an ultra-narrow pH range, 4.2-4.9, has been utilized to detect alpha 1-antitrypsin or alpha 1-protease inhibitor (PI) allele products in 2 US white and 3 US black populations as well as 1 native African black population. In addition to the 3 common alleles PI*M1, PI*M2 and PI*M3, products of the 4th allele PI*M4 have been identified in US whites at low-level frequency. The presence of the PI*S, PI*Z and PI*I alleles has also been verified in our population samples. While the PI*S allele is present at a polymorphic level in US whites, it is only present sporadically in US blacks and is completely absent in African blacks. The PI*Z allele was not detected in the black populations tested. The PI allele frequency data have been used to calculate white admixture in US blacks.
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CYP2D6 allele frequency in European Caucasians, Asians, Africans and their descendants.
Bradford LD.
Department of Psychiatry and Medicine, Morehouse School of Medicine, 720 Westview Dr. S.W., Atlanta, GA, 30310-1495, USA. Bradford@msm.edu
Over 40 cytochrome P450 (CYP) 2D6 allelic variants have been discovered thus far. The alleles may be classified on the basis of the level of activity for which they encode CYP2D6 enzymes, into functional, non-functional and reduced function groups. CYP2D6 allele frequency is known to vary amongst racial/ethnic groups. Generally, for European Caucasians and their descendants, the functional group of alleles are predominant, with a frequency of 71%. Non-functional alleles represent 26% of the variability, mainly CYP2D6*4. In Asians and their close descendants, functional alleles represent only ~ 50% of the frequency of CYP2D6 alleles. Asians and Pacific Islanders have a high frequency (median = 41%) of a reduced function allele, CYP2D6*10, contributing to the population shift to the right of metabolic rates indicating slower metabolism. Information concerning Amerindians from North (Canada), Central and South America indicate comparatively low frequencies of CYP2D6*10, perhaps a "founders" effect. The frequency of functional alleles in Africans and African Americans is also about 50%. Both Africans and African Americans have reduced function alleles representing 35% of allele variation, mainly CYP2D6*17. African Americans, however, have more than twice the median frequency of nonfunctional alleles compared with Africans (14.5% vs 6.3%). Non-functional and reduced function alleles represent about 50% of allele frequency in Black populations but a much greater variety than carried in Asians. Since alleles which encode for no or reduced functioning clearly affect metabolic activity of drugs mediated by CYP2D6, studies are needed in populations in which these alleles play a major role in order to assure optimal dosing recommendations are based on empirical pharmacogenetics.
Publication Types:
· Review
· Review, Tutorial
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Genetic relationships of Asians and Northern Europeans, revealed by Y-chromosomal DNA analysis.
Zerjal T, Dashnyam B, Pandya A, Kayser M, Roewer L, Santos FR, Schiefenhovel W, Fretwell N, Jobling MA, Harihara S, Shimizu K, Semjidmaa D, Sajantila A, Salo P, Crawford MH, Ginter EK, Evgrafov OV, Tyler-Smith C.
Department of Biochemistry, University of Oxford, United Kingdom.
We have identified a new T-->C transition on the human Y chromosome. C-allele chromosomes have been found only in a subset of the populations from Asia and northern Europe and reach their highest frequencies in Yakut, Buryats, and Finns. Examination of the microsatellite haplotypes of the C-allele chromosomes suggests that the mutation occurred recently in Asia. The Y chromosome thus provides both information about population relationships in Asia and evidence for a substantial paternal genetic contribution of Asians to northern European populations such as the Finns.
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Genetic relationships of Europeans, Asians and Africans and the origin of modern Homo sapiens.
Nei M, Liv****s G.
Center for Demographic and Population Genetics, University of Texas Health Science Center, Houston.
To study the evolutionary relationships of the three major groups of humans, Europeans, Asians and Africans, the genetic distances between them were computed by using 4 different sets of genetic loci (84 protein loci, 33 blood group loci, 8 HLA and immunoglobulin loci, and 61 DNA markers). The results obtained indicate that the overall genetic distance between Europeans and Asians is significantly lower than that between Europeans and Africans of that between Asians and Africans and support the hypothesis of an African origin of modern humans. This seems to be the first study to establish the evolutionary relationships of the three major groups of humans at a statistically significant level.
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Origins and affinities of modern humans: a comparison of mitochondrial and nuclear genetic data.
Jorde LB, Bamshad MJ, Watkins WS, Zenger R, Fraley AE, Krakowiak PA, Carpenter KD, Soodyall H, Jenkins T, Rogers AR.
Department of Human Genetics, Eccles Institute of Human Genetics, University of Utah Health Sciences Center, Salt Lake City 84112, USA.
To test hypotheses about the origin of modern humans, we analyzed mtDNA sequences, 30 nuclear restriction-site polymorphisms (RSPs), and 30 tetranucleotide short tandem repeat (STR) polymorphisms in 243 Africans, Asians, and Europeans. An evolutionary tree based on mtDNA displays deep African branches, indicating greater genetic diversity for African populations. This finding, which is consistent with previous mtDNA analyses, has been interpreted as evidence for an African origin of modern humans. Both sets of nuclear polymorphisms, as well as a third set of trinucleotide polymorphisms, are highly consistent with one another but fail to show deep branches for African populations. These results, which represent the first direct comparison of mtDNA and nuclear genetic data in major continental populations, undermine the genetic evidence for an African origin of modern human
Interethnic differences of drug-metabolizing enzymes.
Gaedigk A.
Children's Mercy Hospital Kansas City, Department of Pediatrics, University of Missouri-Kansas City, 64108, USA.
Polymorphisms exhibited by drug-metabolizing enzymes are well known and have been investigated for many years. Recently, the exploding field of pharmacogenetics has focused not only on the characterization of enzymes responsible for drug biotransformation but also, on describing the sources of variability in enzyme activity. While initial observations and studies focused on populations of Caucasian origin, reports for other populations followed. The incidence of a poor or slow metabolizer phenotype for a given enzyme caused by allelic variants may vary significantly between populations. The question arises as to whether a prediction of the phenotype (i.e. distribution and/or enzyme activity) can be accurately ascertained from genotype information gathered in a related population. This is exemplified by NAD(P):quinone oxidoreductase (NQO1) investigated in Canadian Native Indian (CNI), Inuit and Chinese populations and the cytochromes P4502C19 and 2D6. While the two North American Native populations are genetically distinct, they are both descendants from northern Asia. Consequently, one might suspect that on a pharmacogenetic basis, CNI and Inuit would be more comparable to Chinese as opposed to Caucasian populations. This is certainly not the case as demonstrated for all three enzymes. Also, for a reliable phenotype prediction, one needs to pay attention to ethnic "mixing" which occurs between certain populations. Ethnic diversity constitutes both a challenge and an opportunity to prudently apply pharmacogenetics so that variability in both drug disposition and effect may be better understood.
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Blacks develop a higher peak bone mass than whites which is associated with a reduced risk for bone fracture. The physiological basis for the difference in bone mass was investigated by metabolic balance and calcium kinetic studies in adolescent black and white girls. The hypothesis that the greater peak bone mass in blacks compared with whites is due to suppressed bone resorption was tested. Subjects were housed in a supervised environment for 3 wk during which time they consumed a controlled diet and collected all excreta. Subjects were given stable calcium isotopes orally and intravenously after 1 wk adaptation. Blacks have greater calcium retention (mean +/- SD, 11.5 +/- 6.1 vs. 7.3 +/- 4.1 mmol/d, P less than 0.05) consistent with greater bone formation rates (49.4 +/- 13.5 vs. 36.5 +/- 13.6 mmol/d, P less than 0.05) relative to bone resorption rates (37.4 +/- 13.2 vs. 29.4 +/- 10.9 mmol/d, P = 0.07), increased calcium absorption efficiency (54 +/- 19 vs. 38 +/- 18%, P less than 0.05) and decreased urinary calcium (1.15 +/- 0.95 vs. 2.50 +/- 1.35 mmol/d, P less than 0.001), compared with whites. The racial differences in calcium retention in adolescence can account for the racial differences in bone mass of adults.
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This study investigated the effects of visual and verbal racial cues and their consistency on physiological indices of attention, arousal, and valence. Subjects were exposed to a series of short clips containing a digitized Black face or White face reading a priming sentence. The priming sentence was recorded from two males, one Black and one White. Clips contained either still faces, animated faces with lip synch, or no face at all (voice only). Subjects’ heart rate and skin conductance were recorded during exposure to stimuli. Preliminary results indicate that Black faces elicit responses consistent with greater automatic attention and negative valence than those elicited by White faces. Voice alone did not lead to any significant differences in autonomic response. Consistency interacted with racial cues such that inconsistency increased attention to a White face but decreased attention to a Black face. Results will be discussed in terms of racial framing and psychological processing of media.
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Since tympanometric results represent preliminary data in considering middle ear functions, statistical comparisons of the estimated ear canal volume, the static admittance and the tympanometric peak pressure between the two racial groups were carried out. Statistically significant differences were found in the former two parameters between the two racial groups using the independent two-tailed t-test (for canal volume, t = 3.807, df = 118, p < .005; for static admittance, t = 6.403, df = 118, p < .0001). Accordingly, both canal volume and static admittance were smaller in Chinese than in Caucasians. It is possible that the racial differences in the canal volume and static admittance are at least two of the underlying reasons for the different frequency distributions of OAEs found.
Another possible source of racial differences in SOAE characteristics is cochlear differences. Different levels of melanin affect human’s pigmentation, and have been postulated to affect hearing because the specialized melanocytes form an important component of the stria vascularis in the cochlea (Garber et al., 1982). Therefore, physiological variations inside the cochlea due to different levels of melanin in different racial groups are suspected. In the study by Whitehead et al. (1993), the greatest difference in SOAE expressions (although statistically not significant) was found between Negroes and Caucasians. Since the difference of SOAE prevalence or characteristics in people with different levels of melanin is not dramatic, Negroes and Caucasians would be the two most suitable racial groups for any further study
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Conclusions
As have others before them, the researchers found that the contribution of nasal breathing to E diminishes with increasing exercise effort. However, they also found that nasal ventilation during exercise varies as a function of both race and gender.
African-Americans have a greater nasal contribution to breathing during exercise than Caucasians. It may be that this interracial difference is due to the former's ability to achieve greater maximal flow rates through their nose, although this dependence requires further investigation.
At relative exercise efforts, women also had a greater nasal contribution to breathing during exercise than men. This gender difference is explained by the fact that the women achieved lower E than men at a given percentage of their maximum work capacity. Because oral augmentation during exercise was shown to be a function of E, the women did not need to augment their breathing orally until much later in their relative work effort.
These racial and gender-related differences in route of breathing during exercise may be important for determining relative risks of individuals to environmental or occupational exposures of potentially toxic gases or particulate matter.
Source: August 2003 edition of the Journal of Applied Physiology.
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Although the issue of subgroup variation in the incidence and onset age of specific DSM-IV alcohol use disorder symptoms has not been addressed in the empirical literature, several investigators have examined racial/ethnic and gender variation in the prevalence of heavy drinking and alcohol-related problems. These studies indicate heavy drinking is more common among males than among females (Dawson et al., 1995; Knupfer, 1989; Muthen and Muthen, 2000), among younger than among older drinkers (Knupfer, 1989), and among whites than among blacks or Hispanics (Dawson et al., 1995; Knupfer, 1989). From 18 years of age through the mid-30s, drinking-related problems are more likely among whites than among blacks; but from the mid-30s on, drinking-related problems are more likely among blacks and Hispanics than among whites (Muthen and Muthen, 2000)....
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Blacks at Higher Risk for Death from Heart Failure, Finds NHLBI Study
The results of a new study suggest that black patients with congestive heart failure are at higher risk for death and for worsening of their disease than similarly treated white patients.
"Congestive heart failure is a devastating disease affecting 600,000 black patients. If research confirms a difference between black and white survival and identifies the underlying cause of this difference, we may see improved treatment of blacks with heart failure and a greater understanding of this disease among all patients," said Dr. Claude Lenfant, Director of the National Heart, Lung, and Blood Institute (NHBLI), which funded the study.
The new findings, published in the February 25 issue of the New England Journal of Medicine, are based on data collected from the Studies of Left Ventricular Dysfunction (SOLVD). SOLVD found that patients with chronic congestive heart failure had fewer deaths and hospitalizations when treated with an ACE inhibitor, a drug which blocks the constriction of blood vessels.
In the new "retrospective" analysis, Dr. Daniel Dries of the NHLBI and colleagues looked back at the SOLVD results and analyzed racial differences. They reported that 42 percent of blacks in the treatment component of the study (patients with symptoms) and 22 percent of blacks in the prevention component (without symptoms) died compared to 36 and 14 percent of whites respectively. In addition, black patients were at increased risk for progression of the disease.
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New research suggests that a child’s race may be a factor in determining his/her susceptibility to tobacco toxins associated with environmental tobacco smoke (ETS). The study, published in the March issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians (ACCP), reveals that African American children with asthma, who are exposed to ETS, have significantly higher toxin levels when compared to their Caucasian counterparts.
“African American children suffer from higher rates of tobacco-related disorders, such as asthma, sudden-infant death syndrome, and low birth weight, and we need to know why,” said lead author Stephen Wilson MD, University of Cincinnati. “So our goal is to understand how certain populations—particularly those groups who are most susceptible—respond to ETS exposure.”
Dr. Wilson and colleagues from the Cincinnati Children’s Hospital Medical Center examined 220 tobacco-exposed children with asthma, who had previously participated in the Cincinnati Asthma Prevention study. Researchers studied a bi-racial, community-based sample (55% African American) of children ranging in ages 5 to 12. All of the children had physician-diagnosed asthma, symptoms consistent with persistent asthma, and were exposed to at least five cigarettes per day in or around the home.
Researchers tested for levels of cotinine, a nicotine metabolite, by collecting serum and hair samples at baseline, 6 months, and 1 year. Serum samples accounted for short-term tobacco exposure and hair samples accounted for long-term tobacco exposure.
“Cotinine is a product of nicotine metabolism. When people inhale or ingest nicotine, the body uses proteins to convert it into cotinine,” said Dr. Wilson, “and, currently, measuring cotinine in various biologic specimens is a widely used method for assessing nonsmokers’ exposure to ETS.”
Researchers also avoided reporting parental bias by actively measuring levels of tobacco smoke in the home. Each study participant had a nicotine dosimeter placed in his or her home at baseline and at the 6-month visit. These dosimeters were removed at the 6-month and 1-year visits, and were used to objectively measure each child’s level of ETS exposure.
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