Testosterone (T) plays a key role in the increase and maintenance of muscle mass and bone density in adult men. Life history theory predicts that environmental stress may prompt a reallocation of such investments to those functions critical to survival. We tested this hypothesis in two studies of rural Bolivian adult men by comparing free T levels and circadian rhythms during late winter, which is especially severe, to those in less arduous seasons. For each pair of salivary TAM/TPM samples (collected in a ~12-hour period), circadian rhythm was considered classic (CCLASSIC) if TAM>110%TPM, reverse (CREVERSE) if TPM>110%TAM, and flat (CFLAT) otherwise. We tested the hypotheses that mean TAM>mean TPM and that mean TLWTOTHER-PM (A: p=0.035, B: p=0.0005) and TOTHER-AM>TLW-AM (A: p=0.054, B: p=0.007); TPM did not vary seasonally, and T diurnality was not significant during late winter. T diurnality varied substantially between days within an individual, between individuals and between seasons, but neither T levels nor diurnality varied with age. These patterns may reflect the seasonally varying but unscheduled, life-long, strenuous physical labor that typifies many non-industrialized economies. These results also suggest that single morning samples may substantially underestimate peak circulating T for an individual and, most importantly, that exogenous signals may moderate diurnality and the trajectory of age-related change in the male gonadal axis.
andrology; testosterone; seasonality; circadian rhythms; aging; Bolivia
The centrality of emotion in cognition and social intelligence, as well as its impact on health, has intensified investigation into the causes and consequences of individual variation in emotion regulation. Central processing of experience directly informs regulation of endocrine axes, essentially forming a neuro-endocrine continuum integrating information intake, processing, and physiological and behavioral response. Two major elements of life history—resource allocation and niche partitioning—are served by linking cognitive-affective with physiologic and behavioral processes. Scarce cognitive resources (attention, memory, time) are allocated under guidance from affective co-processing. Affective-cognitive processing, in turn, regulates physiologic activity through neuro-endocrine outflow and thereby orchestrates energetic resource allocation and trade-offs, both acutely and through time. Reciprocally, peripheral activity (e.g., immunologic, metabolic or energetic markers) influences affective-cognitive processing. By guiding attention, memory, and behavior, affective-cognitive processing also informs individual stances toward, patterns of activity in, and relationships with the world. As such, it mediates processes of niche partitioning that adaptively exploit social and material resources. Developmental behavioral neurobiology has identified multiple factors that influence the ontogeny of emotion regulation to form affective and behavioral styles. Evidence is reviewed documenting roles for genetic, epigenetic, and experiential factors in the development of emotion regulation, social cognition and behavior with important implications for understanding mechanisms that underlie life history construction and the sources of differential health. Overall, this dynamic arena for research promises to link the biological bases of life history theory with the psychobehavioral phenomena that figure so centrally in quotidian experience and adaptation, particularly for humans.
epigenetics; personality; temperament; niche partitioning; mental health
Secular trends towards earlier puberty, possibly caused by new environmental triggers, provide a basis for periodic evaluation of the influence and interaction of genetic and environmental effects on pubertal timing. In such studies, a practical marker that reflects timing of puberty in both genders needs to be used. We investigated genetic and environmental influences on pubertal timing by using change in the relative height between early and late adolescence (HD:SDS, height difference in standard deviations) as a new marker of pubertal timing. HD:SDS correlated well with age at peak height velocity in a population of men and women with longitudinal growth data. In 2,309 twin girls and 1,828 twin boys, HD:SDS was calculated between height SDs at age 11.5 and 17.5, and 14.0 and 17.5 years, respectively. Quantitative genetic models for twin data were fitted to estimate the genetic contribution to HD:SDS. We also investigated whether the same genetic factors influenced individual differences between HD:SDS and development of secondary sex characteristics prospectively collected by pubertal development scale (PDS). Genetic effects contributed to 86 and 82% of the variance in HD:SDS in girls and boys, respectively, when using the same model including additive genetic and specific environmental factors. In girls, 30% and in boys, 49% of the genetic factors affecting PDS and HD:SDS were the same. Future comparison of the results of periodic evaluations allows estimation of possible changes in the effects of environment on timing of puberty. In such studies, HD:SDS can be used as a practical marker of pubertal timing.
Lower birth weight within the normal range predicts adult chronic diseases, but the same birth weight in different ethnic groups may reflect different patterns of tissue development. Neonatal body composition was investigated among non-Hispanic Caucasians and African Americans, taking advantage of variability in gestational duration to understand growth during late gestation.
Air displacement plethysmography assessed fat and lean body mass among 220 non-Hispanic Caucasian and 93 non-Hispanic African American neonates. The two ethnic groups were compared using linear regression.
At 36 weeks gestation, the average lean mass of Caucasian neonates was 2,515 g vs. that of 2,319 g of African American neonates (difference, P = 0.02). The corresponding figures for fat mass were 231 and 278 g, respectively (difference, P = 0.24). At 41 weeks, the Caucasians were 319 g heavier in lean body mass (P < 0.001) but were also 123 g heavier in fat mass (P = 0.001). The slopes for lean mass vs. gestational week were similar, but the slope of fat mass was 5.8 times greater (P = 0.009) for Caucasian (41.0 g/week) than for African American neonates (7.0 g/week).
By 36 weeks of gestation, the African American fetus developed similar fat mass and less lean mass compared with the Caucasian fetus. Thereafter, changes in lean mass among the African American fetus with increasing gestational age at birth were similar to the Caucasian fetus, but fat accumulated more slowly. We hypothesize that different ethnic fetal growth strategies involving body composition may contribute to ethnic health disparities in later life.
Positive selection for inherited mutations in breast and ovarian cancer predisposing genes, BRCA1 and BRCA2, may contribute to the high frequency of BRCA mutations among the Ashkenazi Jewish population. Impact of BRCA mutations on fertility has not been generally explored in epidemiologic studies. There are reports of distorted sex ratios in BRCA carrier families but these findings have been attributed to bias. We investigated the effect of BRCA mutations on female fertility and offspring sex ratio in a study of 260 Ashkenazi Jewish women with ovarian cancer and 331 controls, unselected for age or family history of the disease. Pregnancy success was similar for 96 mutation carrier (0.84) and 164 noncarrier cases (0.87) and controls (0.83). After adjusting for covariates, there were no significant differences between BRCA carrier and noncarrier cases and controls with regards to fertility, despite lower pregnancy rates among all cases compared to controls (P = 0.0049). Male/female sex ratios were significantly lower among offspring of carriers (0.71) than offspring of noncarriers (0.95) or those of the controls (0.99). Comparisons among the three groups yielded statistically significant distortion against males among the offspring of known and obligate BRCA carriers compared to noncarriers (OR = 0.74, 95% CI:0.55–0.99) and controls (OR = 0.71, 95% CI:0.54–0.94). In conclusion, we did not find evidence for an effect of BRCA mutations on female fertility. We found a significant excess of females among the offspring of female carriers of BRCA1 and BRCA2 mutations. Potential contribution of observed sex ratio distortions to positive selection for BRCA mutations may warrant further investigation.
The ratios of anthropometric measures are used to estimate obesity while controlling for allometric scaling. A good index should be uncorrelated with its denominator; this often requires exponentiation of the denominator. The stability of the derived exponents across populations is not known. We obtained subscapular (SUBS) and triceps (TRI) skinfolds, weight (WT), height (HT), waist circumference (WC), fat mass (FM), and fat-free mass (FFM) in a population of Guatemalan adults [height 1.63 ± 0.06 m (868 males); 1.51 ± 0.06 m (1047 females)]. We derived exponents for the indices WT/HTP, SUBS/TRIP, TRI/SUBSP, WC/HTP, FM/WTP, and FM/FFMP such that the ratios were free from association with their denominators. The derived exponents were (Men: SUBS/TRI0.88, FM/WT2.69, FM/FFM2.86, WC/HT0.68, and WT/HT2.17; Women: SUBS/TRI0.93, FM/WT2.01, FM/FFM3.37, WC/HT0.47, WT/HT2.03). For all examined indices the derived exponents differed (P < 0.05) from 1 and differed (P < 0.05) between men and women. The exponents for the men also differed from those previously published for Brazilian men (JCK Wells and CG Victora : Int J Obes 29:483–489). The derived indices were not more strongly correlated with adiposity than were simple unexponentiated ratios. Although exponentiation of the denominator eliminates the association of index with its denominator, the resulting exponents lack generalizability across populations, especially those where stunting remains prevalent.
While much prior research has focused on identifying the roles of
major regulatory systems in health risks, the concept of allostatic load
(AL) focuses on the importance of a more multi-systems view of health risks.
How best to operationalize allostatic load, however, remains the subject of
To test a hypothesized meta-factor model of allostatic load composed
of a number of biological system factors, and to investigate model
invariance across sex and ethnicity.
Subjects & Methods
Biological data from 782 men and women, aged 32–47, from the
Oakland, CA and Chicago, IL sites of the Coronary Artery Risk Development in
Young Adults Study (CARDIA) were collected as part of the Year 15 exam in
2000. These include measures of blood pressure, metabolic parameters
(glucose, insulin, lipid profiles, and waist circumference), markers of
inflammation (interleukin-6, C-reactive protein, and fibrinogen), heart rate
variability, sympathetic nervous system activity (12 hr urinary
norepinephrine and epinephrine) and hypothalamic-pituitary-adrenal axis
activity (diurnal salivary free cortisol).
A “meta-factor” model of AL as an aggregate measure
of six underlying latent biological subfactors was found to fit the data,
with the meta-factor structure capturing 84% of variance of all
pairwise associations among biological subsystems. There was little evidence
of model variance across sex and/or ethnicity.
These analyses extend work operationalizing AL as a multi-systems
index of biological dysregulation, providing initial support for a model of
AL as a meta-construct of inter-relationships among multiple biological
regulatory systems, that varies little across sex or ethnicity.
biological risk; allostatic load; gender; ethnicity; CARDIA
To describe the prevalence of cardiometabolic risk factor clustering in Samoan adolescents and to relate risk factor clustering to weight status and general modernization.
Anthropometric and biochemical data collected from adolescents aged 12–17.9 years who participated in the Samoan Family Study of Overweight and Diabetes were used to describe the prevalence of cardiometabolic risk factors (high waist circumference, high blood pressure, high triglyceride level, low–high-density lipoprotein cholesterol, and high fasting serum glucose). A total of 436 adolescents were included in this analysis; 237 (54.4%) from American Samoa (n = 123 males) and 199 (45.6%) from Samoa (n = 90 males). Risk factor clustering was indicated by the presence of ≥3 risk factors.
Cardiometabolic risk factor clustering was greater in American Samoan adolescents (17.9% males, 21.9% females) than Samoan adolescents (1.1% males, 2.8% females). The frequency of risk factor clustering varied according to body mass index status. In males, risk factor clustering was entirely confined to obese adolescents, whereas female adolescents who were overweight or obese were at risk.
Cardiometabolic risk factor clustering is prevalent in the young American Samoan population and is likely to become more prevalent with increasing modernization in Samoan youth. Screening and intervention should be targeted at this age group to reduce the non-communicable disease burden faced by these populations. Am. J. Hum.
Underlying the importance of research on the biology of aging is the fact that many nations face the demographic reality of a rapidly aging populace and the looming healthcare challenges that it brings. This reality is a result of aging itself being the most significant risk factor for a range of the most prevalent diseases, including many cancers, cardiovascular disease and diabetes. Accordingly, interventions are sorely needed which would be able to delay or prevent diseases and disorders associated with the aging process and thereby increase the period of time that aging individuals are in good health (the “health-span”). Caloric restriction (CR) has emerged as a model of major interest as it is widely agreed that CR is the most potent environmental intervention that that delays the onset of aging and extends life span in diverse experimental organisms. A better understanding of the mechanisms by which CR delays aging will reveal new insights into the aging process and the underlying causes of disease vulnerability with age. These novel insights will allow the development of novel treatments and preventive measures for age-associated diseases and disorders.
Previous studies have established an association between adiponectin and type 2 diabetes. It is unclear whether adiponectin will be useful among Samoan Islanders, characterized by markedly elevated levels of obesity, in differentiating those at risk of developing type 2 diabetes.
Cross-sectional, genetic epidemiology study of obesity in American Samoa and Samoa 2002–2003 (n = 1,599). Logistic regression provided adjusted odds ratios and 95% confidence intervals for the association between adiponectin, diabetes, and prediabetes (impaired fasting glucose).
There is a significant decreasing trend in the odds of diabetes and prediabetes across increasing quintiles of adiponectin with an OR of 2.8 (95% CI: 1.6, 5.0) and 2.9 (95% CI: 1.5, 5.7), respectively, in the lowest relative to the highest quintile of adiponectin (P-for-trend = 0.004 and 0.001).
Adiponectin is an important correlate, independent of other risk factors, of the pathogenesis of type 2 diabetes among Samoan islanders and may help distinguish those at higher risk of developing this disease.
Infancy represents a window of development during which long-term immunological functioning can be influenced. In this study, we evaluate proxies of microbial exposures in infancy as predictors of interleukin-4 (IL-4) in young adulthood. Interleukin-4 (IL-4) is an immunoregulatory cytokine that plays a role in the pathogenesis of atopic and allergic disease.
Data come from 1,403 participants in the Cebu Longitudinal Health and Nutrition Survey (CLHNS), an ongoing population-based study in the Philippines. Relationships between microbial and nutritional environments in infancy and plasma IL-4 concentrations in adulthood were evaluated using tobit regression models.
Having older siblings and more episodes of respiratory illness in infancy significantly predicted lower concentrations of plasma IL-4 in adulthood. Unexpectedly, more episodes of diarrheal illness in infancy were associated with higher IL-4. Interactions between a composite household pathogen exposure score, and the duration of exclusive breastfeeding approached significance. This interaction showed that the negative association between household pathogen exposure in infancy and adult IL-4 was only significant for individuals who had been exclusively breastfed for a short duration of time. Finally, currently living in an urban household was unexpectedly, negatively associated with adult IL-4. Associations were independent of early nutrition, socioeconomic status, and urbanicity, as well as current measures of infection, body fat, socioeconomic status, and smoking.
This study builds on a growing body of literature demonstrating that early ecological conditions have long-term effects on human biology by providing evidence that multiple proxies of microbial exposures in infancy are associated with adult IL-4.
interleukin-4; microbial exposures; cytokines; hygiene hypothesis; human ecological immunology
To determine secular trends by birth decade in body mass index (BMI), waist circumference/height (W/Ht), percent body fat (PBF), and fat free mass adjusted for height squared (FFM/Ht2) in children and adolescents aged 8–18 years.
Serial data were analyzed from 628 boys and 591girls aged 8 to 18 years who participated in the Fels Longitudinal Study. Subjects were stratified by birth decade from 1960 through 1999. Means and standard deviations were computed for all measurements by birth decade, age and sex. A repeated-measures analysis of variance was used data to ascertain secular trends separately for boys and girls.
Boys and girls born in the 1990s had significantly higher mean BMI, W/Ht and PBF than did children born in previous decades. Mean FFM/Ht2 was significantly smaller in boys born in the 1990s than boys of the same age born in earlier decades. No secular trend was noted in FFM/ Ht2 in girls by decade of birth.
Our analysis of serial data collected over four decades confirms the secular trend in childhood BMI previously observed in successive cross-sectional studies. Our analysis discloses significant positive secular trends in W/Ht and PBF in both boys and girls and a significant negative secular trend in FFM/Ht2 in boys over the last four decades of the 20th century. The secular changes presage increases in the prevalence of conditions associated with childhood and adolescent obesity – such as hypertension, glucose intolerance, and dyslipidemia – that may appear as early as the second decade of life.
Body Composition; Obesity; Secular Trends; Body Mass Index
Antagonists in the debate over whether the maternal stress response during pregnancy damages or culls fetuses have invoked the theory of selection in utero to support opposing positions. We describe how these opposing arguments arise from the same theory and offer a novel test to discriminate between them. Our test, rooted in reports from population endocrinology that human chorionic gonadotropin (hCG) signals fetal fitness, contributes not only to the debate over the fetal origins of illness, but also to the more basic literature concerned with whether and how natural selection in utero affects contemporary human populations.
We linked maternal serum hCG measurements from prenatal screening tests with data from the California Department of Public Health birth registry for the years 2001–2007. We used time series analysis to test the association between the number of live born male singletons and median hCG concentration among males in monthly gestational cohorts.
Among the 1.56 million gestations in our analysis, we find that median hCG levels among male survivors of monthly conception cohorts rise as the number of male survivors falls.
Elevated median hCG among relatively small male birth cohorts supports the theory of selection in utero and suggests that the maternal stress response culls cohorts in gestation by raising the fitness criterion for survival to birth.
hCG; pregnancy; sex ratio; population endocrinology
Biomarkers of inflammation, including C-reactive protein (CRP) and α1-acid glycoprotein (AGP), have tremendous potential in anthropological, public health, and nutrition research as objective indicators of acute infection; however, their utility is limited by the lack of widely-agreed upon, reliable cutpoints to define infection. We assessed the sensitivity and specificity of CRP and AGP for identifying acute infectious disease episodes among children in the Kilimanjaro region of Tanzania.
Data were available from 43 3 to 5 year old children. CRP and AGP were measured in capillary whole dried blood spots. Two-week morbidity history interviews with children’s primary caregivers were used to detect recent episodes of acute infectious disease. Specimens and morbidity history interviews were collected from each child on 1 (n=13) or 2 (n=30) occasions for 73 paired interviews and specimens.
We evaluated CRP and AGP for identifying acute infection (report of fever, diarrhea, or vomiting in the last week): CRP ≥ 1.1 mg/L had sensitivity of 57.14% and specificity of 86.44%; AGP ≥ 0.76 g/L had sensitivity of 57.14% and specificity of 72.41%. The combined definition (AGP ≥ 0.76 g/L or CRP ≥ 1.1 mg/L) had sensitivity of 71.43% and specificity of 70.69%.
Among children in Kilimanjaro, Tanzania, assessed in whole blood stored as dried blood spots, AGP ≥ 0.76 g/L or CRP ≥ 1.1 mg/L provided the best definition of acute infection. Whether this definition is appropriate for use in other populations remains to be determined.
Biomarker; C-reactive protein; α1-acid glycoprotein; Cutpoint; Acute infection
The prevalence of obesity is increasing rapidly worldwide, which is cause for concern because obesity increases the risk of cardiovascular disease and diabetes, reduces life expectancy and impairs quality of life. A better understanding of the risk factors for obesity is therefore a critical global health concern and human biologists can play an important role in identifying these risk factors in various populations. The objective of this review is to present the evidence that inadequate sleep may be a novel risk factor associated with increased vulnerability to obesity and associated cardiometabolic disease. Experimental studies have found that short-term sleep restriction is associated with impaired glucose metabolism, dysregulation of appetite and increased blood pressure. Observational studies have observed cross-sectional associations between short sleep duration (generally <6 hours per night) and increased body mass index or obesity, prevalent diabetes and prevalent hypertension. Some studies also reported an association between self-reported long sleep duration (generally >8 hours per night) and cardiometabolic disease. A few prospective studies have found a significant increased risk of weight gain, incident diabetes and incident hypertension associated with inadequate sleep. Given the potential link between inadequate sleep and obesity, a critical next step is to identify the social, cultural and environmental determinants of sleep, which would help to identify vulnerable populations. Future human biology research should consider variation in sleep characteristics among different populations and determine whether the associations between sleep and obesity observed in Western populations persist elsewhere.
Sleep; body mass index; obesity; diabetes mellitus; hypertension; cardiovascular diseases
To describe long term food availability and prices from 1961 to 2007 and BMI trends from 1980–2010 in Samoa, and to contextualize these trends within political, economic, cultural, behavioral, and climatic influences.
National level data on food availability and pricing were obtained from the open access database FAO (http://faostat.fao.org). Data for Samoa were collected from annual food balance sheets available for the period 1961 to 2007. Mean BMI for Samoan men and women ages 35–44 years of age is reported from four different time periods, 1979–82, 1991, 2003, and 2010.
Total energy availability increased substantially, by 47%, with more than 900 extra calories available per capita per day in 2007 than in 1961. Many of these extra calories are supplied by dietary fat, the availability of which rose by a proportionally greater amount, 73%. Availability of both meat and vegetable oils rose substantially. Poultry meat increased the most proportionally, from 10 to 117 kcal per capita per day. Coconut products, fruit and starchy root crops – all locally grown – showed little to no increase over this time. As import prices for poultry and mutton increased their availability decreased, but the availability of vegetable oils rose despite a rise in their price. Mean BMI for men and women ages 35–44 years rose 18% rise from 1980–2010.
These long-term trends in food availability and prices, and the temporal pattern of BMI provide national level data for understanding the process of the nutrition transition in Samoa. Further work on consumer food prices, diet, food security and health is needed to further contextualize the transformation of the local food system in Samoa.
food availability; FAO; BMI; Samoa
This investigation used a biomarker of sympathetic nervous system activity novel to biocultural research to test the hypothesis that engaging in religious worship activities would reduce baseline stress levels on a non-worship day among Pentecostals.
As detailed in Lynn et al. (submitted for publication), stress was measured via salivary cortisol and α-amylase among 52 Apostolic Pentecostals in New York’s mid-Hudson Valley. Saliva samples were collected at four predetermined times on consecutive Sundays and Mondays to establish diurnal profiles and compare days of worship and non-worship. These data were reanalyzed using separate analyses of covariance on α-amylase and cortisol to control for individual variation in Pentecostal behavior, effects of Sunday biomarkers on Monday, and other covariates.
There was a significant decrease in cortisol and an increase in α-amylase on a non-worship day compared with a service day. Models including engagement in Pentecostal worship behavior explained 62% of the change in non-service day cortisol and 73% of the change in non-service day α-amylase.
Engagement in Pentecostal worship may be associated with reductions in circulatory cortisol and enhancements in α-amylase activity. Am. J. Hum. Biol. 22:819–822, 2010.
To validate use of chip-based immunoaffinity capillary electrophoresis on dry blood spot samples (DBSS) to measure obesity-related cytokines.
Chip-based immunoaffinity capillary electrophoresis was used to measure adiponectin, leptin and insulin in serum and DBSS in pregnant women, cord blood, and infant heelstick at birth and 6 weeks. Concordance of measurements was determined with Pearson's correlation.
We report high concordance between results obtained from serum and DBSS with the exception of cord blood specimens.
Ease of sample collection and storage makes DBSS an optimal method for use in studies involving neonates and young children.
dry blood spot; adionectin; leptin; insulin
Food has nutritional and non-nutritional components. The latter are not well studied despite the fact that food adulteration has been common. Food adulteration may have reached its peak in cities of western Europe and the US in the 18th and 19th centuries when foods were often purposely contaminated with additives to increase bulk, attractiveness, disguise spoilage and increase profit. Effective regulation of food began in the late 19th and 20th centuries. Nevertheless, today food recalls for bacterial contamination are common, while pesticides and compounds from manufacturing are detected in many foods. Foods with strong reputations for healthiness, such as salmon, may have sizable contaminant contents. The contaminant content of many foods varies by origin and season. Nearly all commercially raised salmon has higher contaminant levels than wild caught salmon. Opting out of the commercial food distribution system is an option, but the value depends on the habitat in which the food is obtained.
Traditionally, the Akwesasne Mohawk Nation has depended on local fish and wildlife for their diet. Now pollution of local waterways has led to the contamination of many local foods, and levels of the contaminant PCBs in the Akwesasne Mohawk people reflect current or past dietary patterns. Many other communities in non-urban settings are exposed to contaminants through long-trail distribution of contaminants in food, air, and/or water. Human biologists considering nutrition, disease, growth, reproduction, aging, to name a few areas, may consider the non-nutritional components of food as many have the ability to alter physiological functioning.
Food; diet; pesticides; PCBs; persistent organic pollutants; Mohawk; Akwesasne
Human adult cognition emerges over the course of development via the interaction of multiple critical neurocognitive networks. These networks evolved in response to various selection pressures, many of which were modified or intensified by the intellectual, technological, and socio-cultural environments that arose in connection with the evolution of genus Homo. Networks related to language and theory of mind clearly play an important role in adult cognition. Given the critical importance of food to both basic survival and cultural interaction, a “theory of food” (analogous to theory of mind) may represent another complex network essential for normal cognition. I propose that theory of food evolved as an internal, cognitive representation of our diets in our minds. Like other complex cognitive abilities, it relies on complex and overlapping dedicated neural networks that develop in childhood under familial and cultural influences. Normative diets are analogous to first languages in that they are acquired without overt teaching; they are also difficult to change or modify once a critical period in development is passed. Theory of food suggests that cognitive activities related to food may be cognitive enhancers, which could have implications for maintaining healthy brain function in aging.
Evaluate associations between birth weight (BW), infancy and childhood weight gain and adult body composition.
Subjects included participants of five birth cohort studies from low and middle income nations (Brazil, Guatemala, India, Philippines, South Africa; n=3432). We modeled adult body composition as a function of BW and conditional weight gain (CW), representing changes in weight trajectory relative to peers, in three age intervals (0-12m, 12-24m, 24m-mid childhood).
In 34 of 36 site- and sex-specific models, regression coefficients associated with BW and CWs were higher for adult fat-free than for fat mass. The strength of coefficients predicting fat-free mass relative to those predicting fat mass was greatest for birth weight, intermediate for CWs through 24 months, and weaker thereafter. However, because fat masses were smaller and showed larger variances than fat-free masses, weaker relationships with fat mass still yielded modest but significant increases in adult % body fat (PBF). CW at 12 months and mid-childhood tended to be strongest predictors of PBF, while BW was generally the weakest predictor of PBF. For most early growth measures, a 1 SD change predicted less than a 1% change in adult body fat, suggesting that any health impacts of early growth on changes in adult body composition are likely to be small in these cohorts.
Birth weight and weight trajectories up to 24 months tend to be more strongly associated with adult fat-free mass than with fat mass, while weight trajectories in mid-childhood predict both fat mass and fat-free mass.
body fat; cohort studies; developing countries; DOHaD; obesity
Little is known about blood cholesterol (blood-C) levels under conditions of infection and limited diet. This study examines blood-C and markers of infection and inflammation in the Tsimane of the Bolivian Amazon, indigenous forager farmers living in conditions that model preindustrial European populations by their short life expectancy, high load of infections and inflammation, and limited diets.
We use multivariate models to determine the relationships between lipid levels and markers of infection and inflammation. Adult Tsimane (N = 418, age 20–84) were characterized for blood lipids, cells, and inflammatory markers in relation to individual loads of parasites and village region.
Most of the Tsimane (60%) carried at least one parasite species, averaging 1.3 species per person. Serum high-density lipoprotein cholesterol (HDL-C), total cholesterol (total-C), and low-density lipoprotein cholesterol (LDL-C) were below the U.S. norms and varied inversely with markers of infection and inflammation: C-reactive protein (CRP), interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), immunoglobulin (Ig) E and eosinophil count. Although no relationship of parasite load to blood-C was found, there was an association between anemia and parasite prevalence.
We conclude that the highly infected environment of the Tsimane is related to low levels of blood total-C, HDL-C, and LDL-C. This may suggest a potential reason why arterial disease is largely absent in the Tsimane.
Measuring multiple hormones simultaneously in a single assay saves sample volume, labor, time, reagents, money and consumables. Thus, multiplex arrays represent a faster, more economically and ecologically sound alternative to singleton assays.
To validate a new, commercially-available multiplex female array produced by Quansys Biosciences against individual immunoassays for the quantification of six hormones in urine samples from women in different reproductive stages.
Urine samples were analyzed using the new Quansys multiplex female hormone array and compared with well-established individual immunoassays for adiponectin, free cortisol, c-peptide, estrone-3-glucuronide (E1G), follicle stimulating hormone beta-subunit (FSH-beta), and human chorionic gonadotropin beta-subunit (hCG-beta). Correlations between assays were assessed using Pearson correlation, linear regression and Bland-Altman analysis. The temporal profiles of free cortisol, E1G, FSH-beta and hCG-beta were also compared.
The multiplex array was highly correlated with the individual immunoassays for five of the tested hormones (Pearson’s correlation coefficient ≥ 0.75), and yielded temporal patterns of hormone profiles consistent with the individual immunoassays for free cortisol, E1G, FSH-beta and hCG-beta.
The Quansys multiplex female hormone array is a valid alternative method to individual immunoassays for the quantification of stress, reproductive and energetic hormones and metabolites in human urine samples and can be used to examine the dynamic interactions between these hormones.
multiplex assay validation; cortisol; reproductive hormones; urine; repetitive measurements
To characterize challenges experienced during stages of female-to-male sex transition and investigate associations between transition-specific measures of psychosocial stress, nocturnal decline in ambulatory blood pressure (amBP), and change in C-reactive protein (CRP) levels.
For this biocultural study, 65 healthy transmen who were using testosterone (T) therapy participated in interviews to assess transition-specific stress experience. They provided perceived stress scores (PSS), self-esteem scores, 24-hour amBP measures, salivary samples for T levels, and a blood spot for CRP levels. Psychosocial stress was examined in relation to amBP and CRP using linear regression while adjusting for age, BMI, and smoking.
There were no differences in mean levels of BP in association with stage of transition. Men reporting stress associated with being “out” as transgender had significantly diminished nocturnal decline in systolic and diastolic amBP compared to men who did not report such stress. The associations remained significant when examined among men in stages 1 and 2 (≤3 yrs on T) but not among men in stage 3 (>3yrs on T) of transition. Men reporting stress related to “passing” as someone born male had higher CRP levels than those who did not report such stress. The association remained significant when examined among men in stages 2 and 3 (>.5–3yrs on T).
Measures of stress that captured individuals’ experiences of gender liminality were associated with diminished nocturnal decline in amBP and increased levels of CRP. There are significant differences between men grouped into different stages of the transition process.
Stress; amBP; CRP; liminality; transition
Brachymesophalangia – V (BMP-V), the general term for a short and broad middle phalanx of the 5th digit, presents both alone and in a large number of complex brachydactylies and developmental disorders. Past anthropological and epidemiological studies of growth and development have examined the prevalence of BMP-V because small developmental disorders may signal more complex disruptions of skeletal growth and development. Historically, however, consensus on qualitative phenotype methodology has not been established. In large-scale, non-clinical studies such as the Fels Longitudinal Study and the Jiri Growth Study, quantitative assessment of the hand is not always the most efficient manner of screening for skeletal dysmorphologies. The current study evaluates qualitative phenotyping techniques for BMP-V used in past anthropological studies of growth and development in order to establish a useful and reliable screening method for large study samples.
A total of 1,360 radiographs from Jiri Growth Study participants aged 3 – 18 years were evaluated. BMP-V was assessed using three methods: 1) subjective evaluation of length and width of the bone; 2) comparison with skeletal age-matched radiographs; and 3) subjective evaluation of the length of the middle 4th and 5th phalanges.
We found that the method that uses skeletal age-matched reference radiographs is the better tool for assessing BMP-V because it considers the shape, rather than solely the length and width of the bone, which can be difficult to judge accurately without measurement. This study highlights the complexity of phenotypic assessment of BMP-V and by extension other brachydactylies.
brachydactyly; BMP-V; phenotype; skeletal dysplasia; hand