Low Mineral Density of a Weight-Bearing Bone Among Adult Women in a High Fertility Population

Evolutionary theories of aging posit that greater reproductive effort causes somatic decline given a fundamental trade-off between investing energy in reproduction and repair. Few studies in high fertility human populations support this hypothesis, and problems of phenotypic correlation can obscure the expected trade-off between reproduction and somatic condition. This cross-sectional study investigates whether greater reproductive effort is associated with reduced calcaneal bone mineral density (BMD) among female Tsimane forager-farmers of lowland Bolivia. We also investigate whether female Tsimane BMD values are lower than sex- and age-matched US reference values, despite the fact that Tsimane engage in higher physical activity levels that can increase mechanical loading. To measure calcaneal BMD, quantitative ultrasonography was performed on 130 women (mean ± SD age = 36.6 ± 15.7, range = 15 – 75) that were recruited regardless of past or current reproductive status. Anthropometric and demographic data were collected during routine medical exams. As predicted, higher parity, short inter-birth interval, and earlier age at first birth are associated with reduced BMD among Tsimane women after adjusting for potential confounders. Population-level differences are apparent prior to the onset of reproduction, and age-related decline in BMD is greater among Tsimane compared to American women. Greater cumulative reproductive burden may lower calcaneal BMD individually and jointly with other lifestyle and heritable factors. Fitness impacts of kin transfers in adulthood may determine the value of investments in bone remodeling, and thus affect selection on age-profiles of bone mineral loss

Low Mineral Density of a Weight-Bearing Bone Among Adult Women in a High Fertility Population

Evolutionary theories of aging posit that greater reproductive effort causes somatic decline given a fundamental trade-off between investing energy in reproduction and repair. Few studies in high fertility human populations support this hypothesis, and problems of phenotypic correlation can obscure the expected trade-off between reproduction and somatic condition. This cross-sectional study investigates whether greater reproductive effort is associated with reduced calcaneal bone mineral density (BMD) among female Tsimane forager-farmers of lowland Bolivia. We also investigate whether female Tsimane BMD values are lower than sex- and age-matched US reference values, despite the fact that Tsimane engage in higher physical activity levels that can increase mechanical loading. To measure calcaneal BMD, quantitative ultrasonography was performed on 130 women (mean ± SD age = 36.6 ± 15.7, range = 15–75) that were recruited regardless of past or current reproductive status. Anthropometric and demographic data were collected during routine medical exams. As predicted, higher parity, short inter-birth interval, and earlier age at first birth are associated with reduced BMD among Tsimane women after adjusting for potential confounders. Population-level differences are apparent prior to the onset of reproduction, and age-related decline in BMD is greater among Tsimane compared with American women. Greater cumulative reproductive burden may lower calcaneal BMD individually and jointly with other lifestyle and heritable factors. Fitness impacts of kin transfers in adulthood may determine the value of investments in bone remodeling, and thus affect selection on age-profiles of bone mineral loss

Validation of an enzyme- linked immunoassay assay for osteocalcin, a marker of bone formation, in dried blood spots

ObjectivesInvestigating factors that contribute to bone loss and accretion across populations in remote settings is challenging, particularly where diagnostic tools are scarce. To mitigate this challenge, we describe validation of a commercial ELISA assay to measure osteocalcin, a biomarker of bone formation, from dried blood spots (DBS).MethodsWe validated the Osteocalcin Human SimpleStep ELISA kit from Abcam (ab1951214) using 158 matched plasma and DBS samples. Passing- Bablok regression analysis assessed the relationships between plasma and DBS osteocalcin concentrations. Dilutional linearity and spike and recovery experiments determined if the DBS matrix interfered with osteocalcin measurement, and intra- and inter- assay coefficients of variation (CVs) were calculated. Limit of detection, analyte stability, and specific forms of osteocalcin measured by the kit were also investigated.ResultsMean plasma osteocalcin value was 218.2 ng/mL (range 64.6- 618.1 ng/mL). Linear relationships existed between plasma and DBS concentrations of osteocalcin, with no apparent bias in plasma vs DBS concentrations. There was no apparent interference of the DBS matrix with measurement of osteocalcin in DBS. Intra- assay CV for DBS was ~8%, while average inter- assay CV was 14.8%. Limit of detection was 0.34- ng/mL. Osteocalcin concentrations were stable in DBS stored at - 28°C and room temperature, but not those stored at 37°C. This ELISA kit detects total osteocalcin.ConclusionsOsteocalcin, a bone formation biomarker, can be measured from DBS. Combined with a previously validated DBS assay for TRACP- 5b, a bone resorption biomarker, these assays have the potential to help researchers disentangle the many factors contributing to bone strength.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162811/2/ajhb23394.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162811/1/ajhb23394_am.pd

Market Integration and Soil-Transmitted Helminth Infection among the Shuar of Amazonian Ecuador

Background Soil-transmitted helminth (STH) infections have many negative health outcomes (e.g., diarrhea, nutritional deficiencies) that can also exacerbate poverty. These infections are generally highest among low-income populations, many of which are also undergoing market integration (MI; increased participation in a market-based economy). Yet the direct impact of MI-related social and environmental changes on STH infection patterns is poorly understood, making it unclear which lifestyle factors should be targeted to better control disease spread. This cross-sectional study examines if household infrastructure associated with greater MI is associated with lower STH burdens among Indigenous Ecuadorian Shuar. Methods Kato-Katz fecal smears were used to determine STH infection status and intensity (n = 620 participants; 308 females, 312 males, aged 6 months—86 years); Ascaris lumbricoides (ascarid) and Trichuris trichiura (whipworm) were the primary infection types detected. Structured interviews assessing lifestyle patterns (e.g., measures of household infrastructure) measured participant MI. Multilevel regression analyses and zero-inflated negative binomial regression models tested associations between MI measures and STH infection status or intensity, controlling for individual and community characteristics. Results Participants residing in more market-integrated households exhibited lower infection rates and intensities than those in less market integrated households. Parasite infection status and T. trichiura infection intensity were lower among participants living in houses with wood floors than those with dirt floors, while individuals using well or piped water from a spring exhibited lower A. lumbricoides infection intensities compared to those using river or stream water. Unexpectedly, latrine type was not significantly related to STH infection status or intensity. These results suggest that sources of exposure differ between the two helminth species. Conclusions This study documents associations between household measures and STH infection among an Indigenous population undergoing rapid MI. These findings can help healthcare programs better target interventions and reduce STH exposure among at-risk populations

Market Integration Predicts Human Gut Microbiome Attributes across a Gradient of Economic Development

Economic development is marked by dramatic increases in the incidence of microbiome-associated diseases, such as autoimmune diseases and metabolic syndromes, but the lifestyle changes that drive alterations in the human microbiome are not known. We measured market integration as a proxy for economically related lifestyle attributes, such as ownership of specific market goods that index degree of market integration and components of traditional and nontraditional (more modern) house structure and infrastructure, and profiled the fecal microbiomes of 213 participants from a contiguous, indigenous Ecuadorian population. Despite relatively modest differences in lifestyle across the population, greater economic development correlated with significantly lower within-host diversity, higher between-host dissimilarity, and a decrease in the relative abundance of the bacterium Prevotella. These microbiome shifts were most strongly associated with more modern housing, followed by reduced ownership of traditional subsistence lifestyle-associated items

Implications of market integration for cardiovascular and metabolic health among an indigenous Amazonian Ecuadorian population

BackgroundMarket integration (MI), the suite of social and cultural changes that occur with economic development, has been associated with negative health outcomes such as cardiovascular disease; however, key questions remain about how this transition manifests at the local level.AimThe present paper investigates the effects of MI on health among Shuar, an indigenous lowland Ecuadorian population, with the goal of better understanding the mechanisms responsible for this health transition.Subjects and methodsThis study examines associations between measures of MI and several dimensions of cardiovascular and metabolic health (fasting glucose, lipids [LDL, HDL and total cholesterol; triglycerides] and blood pressure) among 348 adults.ResultsOverall, Shuar males and females have relatively favourable cardiovascular and metabolic health. Shuar who live closer to town have higher total (p < 0.001) and HDL cholesterol (p < 0.001), while Shuar in more remote regions have higher diastolic blood pressure (p = 0.007). HDL cholesterol is positively associated with consumption of market foods (r = 0.140; p = 0.045) and ownership of consumer products (r = 0.184; p = 0.029).ConclusionsThis study provides evidence that MI among Shuar is not a uniformly negative process but instead produces complex cardiovascular and metabolic health outcomes

Regional variation in Ascaris lumbricoides and Trichuris trichiura infections by age cohort and sex: effects of market integration among the indigenous Shuar of Amazonian Ecuador

Background: Soil-transmitted helminth (STH) infection peaks during childhood and varies by sex. The impact of market integration (MI) (increasing production for and consumption from a market-based economy) on these infection patterns, however, is unclear. In this study, STH infection is examined by sex and age among indigenous Shuar inhabiting two regions of Amazonian Ecuador: (1) the modestly market-integrated Upano Valley (UV) and (2) the more traditional Cross-Cutucú (CC) region. Methods: Kato-Katz fecal smears were examined for parasite presence and infection intensity. Factorial ANOVAs and post hoc simple effects analyses were performed by sex to compare infection intensity between regions and age categories (infant/child, juvenile/adolescent, adult). Results: Significant age and regional differences in Ascaris lumbricoides and Trichuris trichiura infection were detected. Overall, infants/children and juveniles/adolescents displayed higher parasite loads than adults. CC females exhibited higher A. lumbricoides loads than UV females, while the opposite pattern was observed for T. trichiura infection in males. Conclusions: Regional infection patterns varied by sex and parasite species, perhaps due to MI-linked environmental and lifestyle changes. These results have public health implications for the identification of individuals at risk for infection and contribute to ongoing efforts to track changes and alleviate STH infection in indigenous populations undergoing MI

Reproductive Trade-Offs in Skeletal Health and Physical Activity among the Indigenous Shuar of Ecuadorian Amazonia: A Life History Approach

xx, 229 p. : ill. (some col.)Reproductive effort is a central element of human biology and ecology. Particularly for females, reproduction is energetically demanding, with elevated metabolic costs during pregnancy and lactation, followed by high child care costs. To satisfy energetic needs, women can adopt various physiological and behavioral strategies. On a physiological level, the energetic requirements of offspring may be met by adjusting metabolic allocation and/or drawing on maternal bodily reserves. On a behavioral level, women may reduce energy expenditure and/or increase energy intake. This study examined reproductive trade-offs in activity and skeletal health among the indigenous Shuar forager-horticulturalists of Ecuadorian Amazonia and had two main objectives. First, this research examined trade-offs in energy use during female reproductive states and behavioral adjustments made by females and males to meet high reproductive demands. Second, this study investigated skeletal health profiles among Shuar, as well non-Shuar Colonos, to identify the relationships between female reproductive factors and skeletal health. Research was conducted among adults in four Morona-Santiago communities. Skeletal health was measured using calcaneal ultrasonometry, and physical activity was measured using accelerometry. Extensive information on sociodemographics and reproduction was assessed through structured interviews. Age-related declines in bone mineral density (BMD) were observed for Shuar and Colonos, while Shuar BMD was significantly higher than that of other populations. These results suggest that normative data from developed countries may reflect suboptimal bone density levels. Regarding reproductive effects on skeletal health, results indicate that earlier menarcheal age and greater stature are associated with better bone health in postmenopausal life. These conclusions suggest the importance of the timing of early developmental stages in establishing bone status in adulthood. Results demonstrate that physical activity levels were similar between pregnant/lactating (P/L) and other women. However, P/L women appear to compensate for elevated energetic demands by relying on a male partner who has increased his energy expenditure, suggesting greater participation in subsistence activities. Overall, this study demonstrates the importance of biocultural strategies among women to meet high reproductive costs. Further, it emphasizes the utility of a life history framework for identifying trade-offs in physiology and behavior. This dissertation contains previously published and unpublished co-authored material.Committee in charge: Dr. J. Josh Snodgrass, Chair; Dr. Lawrence S. Sugiyama, Member; Dr. John Lukacs, Member; Dr. John Halliwell, Outside Membe