Paternal effects on the human sex ratio at birth: evidence from interracial crosses

The effects of interracial crossing on the human sex ratio at birth were investigated using United States birth-certificate data for 1972-1979. The sex ratio was 1.059 for approximately 14 million singleton infants born to white couples, 1.033 for 2 million born to black couples, and 1.024 for 64,000 born to American Indian couples. Paternal and maternal race influences on the observed racial differences in sex ratio were analyzed using additional data on approximately 97,000 singleton infants born to white-black couples and 60,000 born to white-Indian couples. After adjustment for mother's race, white fathers had significantly more male offspring than did black fathers (ratio of sex ratios [RSR] = 1.027) and Indian fathers (RSR = 1.022). On the other hand, after adjustment for father's race, white mothers did not have more male offspring than did black mothers (RSR = 0.998) or Indian mothers (RSR = 1.009). The paternal-race effect persisted after adjustment for parental ages, education, birth order, and maternal marital status. The study shows that the observed racial differences in the sex ratio at birth are due to the effects of father's race and not the mother's. The study points to paternal determinants of the human sex ratio at fertilization and/or of the prenatal differential sex survival.     

Segregation distortion in the offspring of Afro-American fathers with postaxial polydactyly.

The unclear pattern of inheritance of postaxial polydactyly prompted this search for evidence of imprinting or change of expression in males and females using material of the Latin American Collaborative Study of Congenital Malformations. The frequency of affected offspring for 196 fathers with polydactyly was compared with that for 233 mothers with the same condition, stratified according to African and non-African ancestry. The postaxial polydactyly prevalence rate among the offspring of affected black fathers (44%) was larger than that in the group of affected black mothers (31%), with no difference between affected nonblack fathers (34%) and affected nonblack mothers (33%). The sex ratio (.51) observed in 631 black propositi and in 829 nonblack propositi with polydactyly (.58) could be a further indication of etiologic heterogeneity for polydactyly between these two ethnic groups. The segregation distortion in favor of affected among the offspring of affected black fathers could be interpreted as the effect of a sex-linked recessive modifier gene acting during gametogenesis on an autosomal dominant polydactyly gene, this modifier being more frequent in Africans.     

Comparison of Cardiovascular Risk Factors in Obese Blacks and Whites

Blacks are known to have higher blood pressure levels, a higher prevalence of hypertension, and higher body weights than whites. However, the interrelationships of these and other cardiac risk factors have not been analyzed in an obese population. We compared blood pressure (BP) and lipid levels in 174 obese blacks and 939 obese white patients who were entering a weight loss program; we also assessed the effects of weight loss on these factors. Prevalence of treated hypertension was similar in blacks and whites (28% vs. 25%, respectively). In patients not taking BP medication, black women weighed more (108 kg) than white women (102 kg) and black and white males' weights were similar (135 kg vs. 131 kg). Systolic and diastolic BP were similar in black and white women; black males had similar SBP but a significantly lower DBP than white males (83 mmHg vs. 89 mmHg, respectively). Lipid levels were similar in black and white women except black women had lower triglycerides (1.30 mmol/L) than white women (1.58 mmol/L, p<0.05); and black males compared to white males had significantly lower total cholesterol (4.76 mmol/L vs. 5.56 mmol/L), LDL-cholesterol (3.15 mmol/L vs. 3.52 mmol/L) and triglycerides (1.31 mmol/L vs. 2.17 mmol/L, p<0.05). Adult-onset obesity adversely affected a number of cardiovascular risk factors in whites, but not in blacks. Blacks lost significantly less weight (?13 kg) than whites (?19 kg). However, controlling for the difference in weight loss, blacks sustained comparable improvement in lipids and blood pressure, except for TC/HDL-C (whites improved significantly more, ?0.36 kg/m2, than blacks, 0.03 kg/m2). Thus, the impact of obesity on cardiovascular risk factors seems ameliorated in blacks com-pared to whites.     

Effect of age,sex, and race on selenium status of healthy residents of Augusta,Georgia

In this study we determined the possible effects of age, sex, and race on selenium (Se) concentration in plasma and erythrocytes and on glutathione peroxidase (GSH-Px) activity in erythrocytes. Two hundred six healthy blacks, whites, males, and females ranging in age from 11 to 60 yr were studied. For the entire population, mean±SDM Se concentrations were 0.104±0.021 μg/mL for plasma and 0.158±0.035 μg/mL for erythrocytes. Mean concentration of Se in plasma was higher in white subjects compared to black subjects (P<0.02). This difference was due exclusively to higher values in young adult white males (age, race, sex interaction). Neither plasma nor erythrocyte Se concentration nor erythrocyte GSH-Px activity were otherwise affected by age. In all groups plasma Se was correlated with erythrocyte Se (P<0.001), but not with glutathione peroxidase. Erythrocyte Se also was correlated inversely with years of smoking (P<0.033) and coffee intake (p<0.01). These results have defined the Se status in this healthy population in Augusta, Georgia as below the reported US mean. The factors underlying the age, race, sex interaction and the health significance of the low Se status in this population should be investigated.     

The Relationship of Ethnicity,Socioeconomic Factors,and Overweight in U.S. Adolescents

Objective: To examine the extent to which race/ethnic differences in income and education account for sex‐specific disparities in overweight prevalence in white, African American, Hispanic, and Asian U.S. teens. Research Methods and Procedures: We used nationally representative data collected from 13,113 U.S. adolescents enrolled in the National Longitudinal Study of Adolescent Health. Logistic regression models were used to examine the relationship of family income and parental education to overweight prevalence (body mass index ≥ 85th percentile of age and sex‐specific cutoff points from the 2000 Centers for Disease Control and Prevention/National Center for Health Statistics growth charts). In addition, we used coefficients from our logistic regression models to project the effects on overweight prevalence of equalizing the socioeconomic status (SES) differences between race/ethnic groups. Results: Keeping adolescents in their same environments and changing only family income and parental education had a limited effect on the disparities in overweight prevalence. Ethnicity‐SES‐overweight differences were greater among females than males. Given that overweight prevalence decreased with increasing SES among white females and remained elevated and even increased among higher SES African‐American females, African‐American/white disparity in overweight prevalence increased at the highest SES. Conversely, disparity was lessened at the highest SES for white, Hispanic, and Asian females. Among males, disparity was lowest at the average SES level. Discussion: One cannot automatically assume that the benefits of increased SES found among white adults will transfer to other gender‐age‐ethnic groups. Our findings suggest that efforts to reduce overweight disparities between ethnic groups must look beyond income and education and focus on other factors, such as environmental, contextual, biological, and sociocultural factors.     

Prevalence and possible etiology of dental enamel hypoplasia

Two hundred black and white adult human skeletons and 200 living black and white children from the greater Cleveland area were examined for evidence of enamel hypoplasia. Enamel hypoplasia, present in varying expressings (pits, lines and grooves), was found to be more prevalent in both skeletal samples, than in the living groups. In the majority of cases, sex differences between white and black males and females through time and space are highly significant for all tooth catagories. Regardless of the mechanisms behind it, prevalence of enamel hypoplasia for both white and black group has significantly declined through time. No evidence suggesting specific etiologies responsible for enamel hypoplasia can be found. In the majority of previously published reports, the etiology is still idiopathic. The reduction in the prevalence of enamel hypoplasia in the groups examined through time may be related to improved nutritional conditions and the elimination or decline of childhood diseases that have been implicated in this condition.     

Epidemiology of noncomplex left ventricular outflow tract obstruction malformations (aortic valve stenosis, coarctation of the aorta, hypoplastic left heart syndrome) in Texas, 1999-2001

BACKGROUND: The left ventricular outflow tract (LVOT) malformations aortic valve stenosis (AVS), coarctation of the aorta (CoA), and hypoplastic left heart syndrome (HLHS) contribute significantly to infant mortality due to birth defects. Previous epidemiology data showed rate differences between male and female and white and black ethnic groups. The Texas Birth Defects Registry, an active surveillance program, enables study in a large, diverse population including Hispanics. METHODS: Records of children up to 1 year old with AVS, CoA, and HLHS born in Texas from 1999 to 2001, were collected from the registry. Those including additional heart defects or a chromosomal anomaly were excluded. Multivariate analysis included: infant sex; United States-Mexico border county residence; and maternal age, race/ethnicity, birthplace, and education. RESULTS: There were 910 cases among 1.08 million live births, of which 499 met inclusion criteria. Multivariate modeling of all LVOT malformations combined demonstrated lower prevalence rate ratios (PRRs) for black males (0.26) and Hispanic males (0.70). Similar results were found for CoA but not AVS or HLHS. Higher PRRs were noted for increased maternal age for LVOT (1.3 for 24-34 years; 1.7 for >34 years), AVS, and HLHS, but not CoA, and higher PRRs across all diagnoses for males (LVOT PRR, 2.4) were noted. CoA PRRs were higher in border county vs. non-border county residents (PRR, 2.1). Maternal education and birthplace were not significant factors. CONCLUSIONS: There are rate differences for males among all 3 ethnic groups. Sex and ethnic differences suggest genetic etiologies, where the ethnic differences could be used to find susceptibility loci with mapping by admixture linkage disequilibrium. Increased CoA rates along the U.S.-Mexico border suggest environmental causes that will require further monitoring.     

Tryptophan, copper and zinc in hair of healthy subjects. Correlation with differences in hair pigmentation

Tryptophan, copper and zinc levels were determined in the hair of 300 healthy subjects divided by sex, age and hair colour. Sex influences tryptophan content in hair, the levels of this amino acid being higher in males than in females. Tryptophan is also higher in infancy (2-5 years) and in both males and females aging around 80 years and over. Hair colour also influences tryptophan levels, which increase from fair to black hair. Copper levels are similar in hair of both males and females, while those of zinc are higher in women. Age influences the distribution of these two metals in human hair. Copper contents in hair of males are higher at the age 20-40 years. In females, values decrease over the age of 60 years. Instead, zinc levels are higher between 20 and 60 years in males, and between 13 and 19 years in females. As regards hair colour, copper is slightly higher in black hair in males and in fair hair in females, and lower in white hair in both sexes. Zinc values appear to be higher in red and lower in white hair in males. In females they are higher in black hair.     

Sex differences in the prevalence of human birth defects: a population-based study.

BACKGROUND: Sex differences in the prevalence of several human birth defects have often been reported in the literature, but the extent of sex differences for most birth defects is unknown. To determine the full extent of sex differences in birth defects in a population, we examined population-based data from the Metropolitan Atlanta Congenital Defects Program (MACDP). METHODS: MACDP records were analyzed for 1968 through 1995. We determined the sex-specific prevalence of all major birth defects, using the total number of live births by sex during these years as the denominator. For each specific defect, we calculated a relative risk with regard to sex on the basis of the ratio of prevalence among males to prevalence among females. Male-female relative risks were also determined for total major birth defects and for several broad categories of defects. RESULTS: The overall prevalence of major defects at birth was 3.9% among males and 2.8% among females. All but two of the major categories of birth defects (nervous system defects and endocrine system defects) had a higher prevalence among males. Defects of the sex organs were eight and one-half times more prevalent among males and accounted for about half of the increased risk of birth defects among males relative to females. Urinary tract defects were 62% more prevalent among males, and gastrointestinal tract defects were 55% more prevalent among males. Among specific defect types, twofold or greater differences in prevalence by sex were common. CONCLUSIONS: Our data indicate that sex differences in the prevalence of specific human birth defects are common, and male infants are at greater risk for birth defects than female infants. Several mechanisms have been proposed to account for these differences.     

Television Viewing Is Not Predictive of BMI in Black and Hispanic Young Adult Females

Previous studies have observed that television (TV) viewing is predictive of obesity and weight gain. We examined whether the cross‐sectional association between TV viewing and BMI varied by racial/ethnic subgroups among young women in Wave III (collected in 2001–2002) of the National Longitudinal Study of Adolescent Health. We used multivariate linear regression to examine the relationship between TV viewing and BMI among 6,049 females while controlling for sociodemographic and health attributes. We stratified the sample by race/ethnicity to better understand the association between TV viewing and BMI across different groups. Black and Hispanic females had higher BMIs (black: 28.5 kg/m², Hispanic: 27.3 kg/m², white: 26.0 kg/m²) than white females, while black females reported higher numbers of hours spent watching TV (black: 14.7 h/week, Hispanic: 10.6 h/week, white: 11.2 h/week) when compared to their white and Hispanic peers. TV viewing was positively associated with BMI (β = 0.79, P = 0.003 for 8–14 vs. ≤7 h/week; β = 1.18, P = 0.01 for >14 vs. ≤7 h/week) independent of race/ethnicity, age, maternal education, history of pregnancy, parental obesity, and household income. However, in models stratified by race/ethnicity, increased TV viewing was associated with increased BMI only among white females; TV viewing was not predictive of higher BMI in black or Hispanic young adult females. Among black and Hispanic females, counseling to decrease TV viewing may be important but insufficient for promoting weight loss.     

Ecological basis of heterochrony in early-ontogenesis gonad development in different races of Kura sturgeon (Acipenser guldenstadti persicus Borodin)

Early germ cell development in Persian sturgeon appears to be faster in the marine environment than in aquaculture conditions. Adaptation plasticity differs significantly for gonad formation and sex determination in the sturgeon fry and depends to differing extents on the temperature. The sturgeon gonads are more sensitive to low temperatures on the early stages of sex determination than in the period of gonad formation; the differences between sexes are preconditioned by the earlier start of sex determination in females when compared to males. The rates of the early gonad and germ cell development in sturgeon are conditioned by its reproduction season. In the population of the late spring race, the delay in both early sex determination and germ cell development stays even for the ages of 1+, 2+, and 3+ when compared to the population of the early spring race. The biophysiological quality of parents is transmitted to their offspring.     

Influence of host weight, sex and reproductive status on helminth parasites of the wild rabbit, Oryctolagus cuniculus, in Navarra, Spain.

A study was carried out in Navarra (northern Spain) on the influence of the weight, sex and reproductive status (lactant, pregnant or lactant + pregnant females and testicular weight for males) of the wild rabbit (Oryctolagus cuniculus) on two cestodes species: Andrya cuniculi and Mosgovoyia ctenoides and four intestinal nematodes: Graphidium strigosum, Trichostrongylus retortaeformis, Nematodiroides zembrae and Dermatoxys hispaniensis. A significantly higher prevalence of A. cuniculi was detected in lactant + pregnant females compared with non-breeding females. Trichostrongylus retortaeformis and N. zembrae showed a significantly higher mean intensity in lactant and lactant + pregnant females than in non-reproductive females. Trichostrongylus retortaeformis presented a higher mean intensity in females than in males, and the mean intensity of the same parasite species was significantly lower in active and inactive males compared with lactant and lactant + pregnant females. There were no significant differences between sexes in the prevalence of helminth parasites. No significant correlation was detected between host weight and the intensity (of infection) of helminths studied. No significant differences in the prevalence and mean intensity of the two cestode species were observed in the three weight categories studied (kittens, juveniles and adults). The prevalence of G. strigosum and mean intensity of T. retortaeformis were significantly higher in older heavier animals than in juveniles.     

An analysis of indeterminate Western blot patterns of black African subjects

The significance of indeterminate Western blotting results was assessed by determining their distribution in attenders of sexually transmitted diseases (STD) and family planning (FP) clinics. As expected, it was found that the former had a highly significantly greater prevalence of HIV infection. Indeterminate results were not found more frequently in STD attenders refuting any association with sexual promiscuity. They were, however, found significantly more frequently amongst black compared to white subjects, but no difference was found between males and females. Indeterminate results appear to be a feature of black African sera and what the significance is, still remains to be elucidated.     

Age, sex, and race influence single-strand break repair capacity in a human population

Recently, we developed an improved comet assay protocol for evaluating single-strand break repair capacity (SSB-RC) in unstimulated cryopreserved human peripheral blood mononuclear cells (PBMCs). This methodology facilitates control of interexperimental variability [A.R. Trzeciak, J. Barnes, M.K. Evans, A modified alkaline comet assay for measuring DNA repair capacity in human populations. Radiat. Res. 169 (2008) 110-121]. The fast component of SSB repair (F-SSB-RC) was assessed using a novel parameter, the initial rate of DNA repair, and the widely used half-time of DNA repair. The slow component of SSB repair (S-SSB-RC) was estimated using the residual DNA damage after 60 min. We have examined repair of gamma-radiation-induced DNA damage in PBMCs from four age-matched groups of male and female whites and African-Americans between ages 30 and 64. There is an increase in F-SSB-RC with age in white females (P<0.01) and nonsignificant decrease in F-SSB-RC in African-American females (P=0.061). F-SSB-RC is lower in white females than in white males (P<0.01). There is a decrease in F-SSB-RC with age in African-American females as compared to white females (P<0.002) and African-American males (nonsignificant, P=0.059). Age, sex, and race had a similar effect on intercellular variability of DNA damage in gamma-irradiated and repairing PBMCs. Our findings suggest that age, sex, and race influence SSB-RC as measured by the alkaline comet assay. SSB-RC may be a useful clinical biomarker.     

Neural tube defects among twin births.

To obtain accurate, unbiased rates of neural tube defects (NTDs) in twins, we conducted a population-based study that included live births and fetal deaths in Los Angeles County, California, ascertaining cases by multiple methods. Twenty-eight twin cases yielded a prevalence-at-birth of 1.6/1,000 twin births, which is significantly higher than the singleton prevalence of 1.1/1,000 births. In twins compared with singletons, the prevalences of both encephalocele and anencephaly are increased, whereas spina bifida is decreased. The twin case male/female sex ratio (.55) is lower than the singleton case sex ratio (.77). Concordance is relatively low at 3.7%, but appears to be higher than recently reported recurrence risks in other low prevalence areas. Stillbirths were most common among female cases and like-sex twins. Our study tends to support proposed etiologic theories associating NTDs with females or monozygotic twins, or both. There is increasing evidence that the etiology of NTDs may differ in high and low prevalence areas. We suggest also that twins and singletons may differ in their response to etiologic factors. The variations among anencephaly, spina bifida, and encephalocele in their association with twinning suggest that there may be different factors that influence the development of each specific NTD. The noted differences among the malformations also indicate that some of the variation among results of other studies of NTDs and twinning may be due to case ascertainment. Including spina bifida cases would decrease the proportion of twins in a study population, while including anencephalics would increase the proportion. Importantly, ascertaining fetal deaths would increase the proportion of anencephalics and case females, so studies of NTDs that do not include fetal deaths will show fewer twins than expected. On the basis of our findings and those of Layde et al., excluding encephaloceles will also decrease the number of twins among NTD cases. When investigating etiologic hypotheses for NTDs, these potential biases must be recognized.     

BMI percentiles and body image discrepancy in black and white adolescents

The purpose of this study was to investigate the relationship between body image discrepancy (BID) and weight status as measured by BMI percentiles (BMI%) among adolescents. A cross-sectional survey was conducted among 265 adolescents at an urban clinic (females: 116 blacks and 63 whites; males: 62 blacks and 24 whites). BID was the difference between ideal and current body images selected from a 13-figure rating scale, and BMI% were calculated from measured weight and height. Regression analyses were conducted separately for girls and boys. Over half of the female and one-third of male adolescents wanted a thinner body. BID was positively related to BMI% with a one-unit increase in BID associated with a 4.84-unit increase in BMI% among females and a 3.88-unit increase in BMI% in males. Both female and male adolescents reported BID beginning at a BMI% corresponding to a normal weight. At zero BID, white females had a BMI% of 62.6, statistically different from black females (BMI% 69.7). At zero BID, white males had a mean BMI% of 69 and black males at a BMI% of 75.8, not statistically different. While black and white differences exist in BID, black female adolescents like their white counterparts are reporting BID at a weight range that is within the "normal". Our study portends the increase in BID with the increasing prevalence of obesity and highlights the need for interventions to help adolescents develop a healthy and realistic body image and healthy ways to manage their weight.     

OBSERVATIONS OF AN UNIDENTIFIED BEAKED WHALE (MESOPLODON SP.) IN THE EASTERN TROPICAL PACIFIC

Multiple sightings of a distinctive but unidentified species of beaked whale have been made in the eastern tropical Pacific. The unidentified whale has two color morphs: a conspicuously marked black and white form (judged to be larger), and a uniformly gray-brown form. Maximum length estimates have been 5–5.5 m. Other features include a relatively flat head, with a small, distinct melon; a moderately long beak; and a low, wide-based, triangular dorsal fin. On most animals the trailing edge of the dorsal fin is only slightly falcate and often appears straight. On the black and white morph, a broad white or cream-colored swathe originates immediately posterior to the dorsal surface of the head and runs posterio-ventrally on either side of the animal. The prevalence of scarring on the black and white animals suggests sexual dimorphism and that these larger, more conspicuously marked animals are adult males, while the smaller, browner, unscarred animals are females and young. Possibilities for identification include: 1) a well-marked race of a known Mesoplodon sp., 2) Mesoplodon (Indopacetus) pacificus or 3) an undescribed species.     

Competing females and caring males. Sex steroids in African black coucals, Centropus grillii

The black coucal is the only known altricial bird species in which females mate with and lay eggs for more than one male and males are responsible for all parental care (classical polyandry). In this species, the left testis is atrophied and it has been speculated that this may result in a reduction of circulating androgens, providing a unique mechanism for reversals in sex roles. We therefore investigated whether there is a reversal in circulating androgens and oestrogens in black coucals. Despite the reversals in sex roles, males had significantly higher levels of plasma testosterone than females, in a pattern typical of that of monogamous male passerines. Testosterone levels of both sexes were higher during the mating than during the premating stage and were low in males during the nestling stage. The concentrations of androstenedione, dehydroepiandrosterone and oestradiol did not differ between the sexes and were generally low. A physiological challenge with gonadotropin-releasing hormone (GnRH) resulted in a significant increase in testosterone in males but not in females, suggesting either that females are not responsive to GnRH or that they express patterns of testosterone that are similar to those of males of species with a polygynous mating system without paternal care, in which testosterone is expressed at maximum levels throughout the breeding season. We conclude that the absence of one testis does not provide a mechanism for sex role reversal in black coucals. Either androgens are not involved in the regulation of male-like traits in females or females are sensitive to relatively low levels of these steroids.     

Red howler monkey birth data II: Interannual,habitat, and sex comparisons

Data presented in this paper are derived from the births and subsequent histories of red howler infants born in two habitats. Overall the sex ratio of infants at birth was about 1:1. Infant survivorship (at 1 yr) was about 80%, and 44% of infant mortality was attributed to infanticide by males. Survivorship curves indicated a dramatic sex difference, with far fewer females than males known to be alive at age 7 yr. However, this sex difference may be inflated because emigrant males are more easily identified than emigrant females, and females may be dispersing beyond the boundaries of the study area at a higher rate. Annual birthrate varied somewhat from year to year and was positively related to rainfall. Annual birthrate tended to be higher in the habitat with lower density and higher growth rate. Consistent with the trends, in annual birthrate, variation in interbirth interval length (TBR after births of surviving infants was related primarily to habitat differences and annual variation in rainfall. Season of birth and maternal age class had no effect on IBI. Infant sex had mostly nonsignificant effects on IBI. A small sample indicated that IBI's were significantly longer after the births of females who eventually became natal breeders than after the births of females who eventually emigrated. This difference might reflect differential parental (maternal) investment of some sort.     

An “epidemic” model of sexual intercourse prevalences for black and white adolescents

Abstract

In adolescence (12–16 years), the prevalence of sexual intercourse increases each year. To explain the increasing yearly prevalences, we propose a recursive equation model of onset of adolescent sexual intercourse. The model allows for an “epidemic” process (the transmission of sexuality from a nonvirgin to a virgin) and a nonepidemic process (two virgins progressing to sexual intercourse). The model also requires that virgin females be pubertally mature before they will progress to sexual intercourse. Adequate fits were obtained to the intercourse prevalences for both black and white respondents. Comparisons of alternative models established that the full model was superior to models that omitted either the nonepidemic process or the requirement of females’ pubertal maturation. The model was able to fit both white and blacks simultaneously, assuming equal transition probabilities in both races. Hence, we propose the hypothesis that race differences in sexual intercourse prevalences may be strongly influenced by the age of initiation of the “epidemic” process and by race difference in females’ rates of pubertal maturation. The results suggested that most new cases of sexual intercourse arose from the epidemic process and that males were more prone to progress to intercourse, given an opportunity.