Heavy metal blood concentrations in association with sociocultural characteristics, anthropometry and anemia among Kenyan adolescents.

OBJECTIVES: To measure heavy metal concentrations among Kenyan youth and quantify associations with sociocultural, demographic, and health factors as well as anthropometry. METHODS: Using data from a study of semi-nomadic pastoralists in Samburu County, Kenya, we measured blood concentrations of lead (Pb), mercury (Hg), and cadmium (Cd) in 161 adolescents. We identified sociocultural, demographic and health characteristics associated with each metal and quantified the association between metals and adolescent anthropometry. RESULTS: Median blood concentrations of Pb, Cd, and Hg were 1.82 µg/dL, 0.24 µg/L and 0.16 µg/L, respectively. Place of residence (highlands vs lowlands) was a determinant of metal concentrations. Hg was inversely related to anemia, and metals were not associated with anthropometry. CONCLUSIONS: In this population of Samburu adolescents, median Pb and Cd blood concentrations were higher than other North American or European biomonitoring studies. These findings motivate further investigation into the environmental sources of metals in this community.

Buffered or impaired: Maternal anemia, inflammation and breast milk macronutrients in northern Kenya.

BACKGROUND: Maternal anemia has adverse consequences for the mother-infant dyad. To evaluate whether and how milk nutrient content may change in ways that could "buffer" infants against the conditions underlying maternal anemia, this study assessed associations between milk macronutrients and maternal iron-deficiency anemia (IDA), non-iron-deficiency anemia (NIDA), and inflammation. METHODS: A secondary analysis of cross-sectional data and milk from northern Kenya was conducted (n = 204). The combination of hemoglobin and transferrin receptor defined IDA/NIDA. Elevated serum C-reactive protein defined acute inflammation. The effects of IDA, NIDA, and inflammation on milk macronutrients were evaluated in regression models. RESULTS: IDA (ß = 0.077, p = .022) and NIDA (ß = 0.083, p = .100) predicted higher total protein (ln). IDA (ß = -0.293, p = .002), NIDA (ß = -0.313, p = .047), and inflammation (ß = -0.269, p = .007) each predicted lower fat (ln); however, anemia accompanying inflammation predicted higher fat (ß = 0.655, p = .007 for IDA and ß = 0.468, p = .092 for NIDA). NIDA predicted higher lactose (ß = 1.020, p = .003). CONCLUSIONS: Milk macronutrient content both increases and decreases in the presence of maternal anemia and inflammation, suggesting a more complicated and dynamic change than simple impairment of nutrient delivery during maternal stress. Maternal fat delivery to milk may be impaired under anemia. Mothers may buffer infant nutrition against adverse conditions or poor maternal health by elevating milk protein (mothers with IDA/NIDA), lactose (mothers with NIDA), or fat (mothers with anemia and inflammation). This study demonstrates the foundational importance of maternal micronutrient health and inflammation or infection for advancing the ecological understanding of human milk nutrient variation.

Development and validation of hair specimen collection methods among extremely short-length Afro-textured hair.

OBJECTIVES: Cortisol, a biomarker of stress, is slowly deposited into the growing hair strands on the head. Meyer, Novak, Hamel, and Rosenberg (2014) established a method for hair cortisol extraction and analysis, and showed that hair cortisol can serve as an integrated measure of psychophysiological stress activity during the period of hormone incorporation into the hair. The hair sample collection methods offered, however, (ie, cutting as close to the scalp as possible with scissors) is inefficient when collecting samples among participants with Afro-textured and extremely short-length hair types. In this article, we propose an alternative method for collecting hair among this group. METHODS: Our proposed alternative method involves sampling hair from all sections of the scalp, rather than the posterior-vertex position alone. This provides more volume of hair making it feasible to extract and analyze cortisol in extremely short-length Afro-textured hair types. To validate this method, we compared a homogeneous specimen of hair cortisol sampled from all regions to that from the posterior-vertex region of the scalp, a region most commonly sampled. RESULTS: There was no statistical difference between the homogeneous mixture and the posterior-vertex region of the scalp. CONCLUSIONS: Our findings suggest that our proposed method may serve as a feasible alternative to the currently prevailing standard collection methodology, and underscores the importance of diversifying hair cortisol research beyond the limitations of developing collection methodologies only suited for straighter-textured hair types.

Design and measurement in a study of war exposure, health, and aging: protocol for the Vietnam health and aging study.

BACKGROUND: Survivors of war throughout the world experience illnesses and injuries that are crucial to understand, given the ongoing treatment and adaptation they demand. In developing countries like Vietnam, where population aging and chronic disease burdens are rapidly rising, aging populations have seen a disproportionate share of armed conflict and related casualties. This paper describes the Vietnam Health and Aging Study (VHAS), a unique resource for investigating mechanisms of association between diverse exposures to armed conflict during the Vietnam War and multiple dimensions of older adult health among survivors of that war. METHODS: The VHAS utilizes a longitudinal design, the first wave of data collection conducted in 2018 among 2447 older adults. A second wave of follow-up data collection, scheduled to take place in 2021, will examine life course, social relational and health and mortality transitions. The VHAS was conducted in four northern Vietnamese districts purposively selected to represent a spectrum of war exposure as indicated by intensity of bombings. Additionally, VHAS uses random sampling within gender and military service subdomains to permit unique gender-specific analyses of military service, trauma exposure and health. The VHAS' face-to-face interviews include modules detailing war and military service experiences; warzone stressors; and multiple dimensions of health such as chronic disease, functional limitation, disability, health behaviors, cognition and psychological health. Biomarker data collected for the full VHAS sample includes anthropometric and functional tests such as grip strength and blood pressure, hair samples for cortisol assay, and capillary blood samples to assay C-reactive protein, cholesterol, HbA1c, and other markers of interest for cardiovascular and other disease risks and for testing the impact of early life stressors on later life health. Blood samples will also permit epigenetic analysis of biological aging. DISCUSSION: Future VHAS investigations will examine dynamic linkages between war exposure, mortality and morbidity, while taking into account the selective nature of each of these processes. Longitudinal analyses will examine late-life health transitions and war-related resiliency.

Health of Philippine Emigrants Study (HoPES): study design and rationale.

BACKGROUND: Immigrants to the United States are usually healthier than their U.S.-born counterparts, yet the health of immigrants declines with duration of stay in the U.S. This pattern is often seen for numerous health problems such as obesity, and is usually attributed to acculturation (the adoption of "American" behaviors and norms). However, an alternative explanation is secular trends, given that rates of obesity have been rising globally. Few studies of immigrants are designed to distinguish the effects of acculturation versus secular trends, in part because most studies of immigrants are cross-sectional, lack baseline data prior to migration, and do not have a comparison group of non-migrants in the country of origin. This paper describes the Health of Philippine Emigrants Study (HoPES), a study designed to address many of these limitations. METHODS: HoPES is a dual-cohort, longitudinal, transnational study. The first cohort consisted of Filipinos migrating to the United States (n = 832). The second cohort consisted of non-migrant Filipinos who planned to remain in the Philippines (n = 805). Baseline data were collected from both cohorts in 2017 in the Philippines, with follow-up data collection planned over 3 years in either the U.S. for the migrant cohort or the Philippines for the non-migrant cohort. At baseline, interviewers administered semi-structured questionnaires that assessed demographic characteristics, diet, physical activity, stress, and immigration experiences. Interviewers also measured weight, height, waist and hip circumferences, blood pressure, and collected dried blood spot samples. DISCUSSION: Migrants enrolled in the study appear to be representative of recent Filipino migrants to the U.S. Additionally, migrant and non-migrant study participants are comparable on several characteristics that we attempted to balance at baseline, including age, gender, and education. HoPES is a unique study that approximates a natural experiment from which to study the effects of immigration on obesity and other health problems. A number of innovative methodological strategies were pursued to expand the boundaries of current immigrant health research. Key to accomplishing this research was investment in building collaborative relationships with stakeholders across the U.S. and the Philippines with shared interest in the health of migrants.

Nutritional, inflammatory, and ecological correlates of maternal retinol allocation to breast milk in agro-pastoral Ariaal communities of northern Kenya.

OBJECTIVES: Vitamin A (VA) is an essential micronutrient required for a range of biological functions throughout life. VA deficiency (VAD) claims an estimated 1 million preschool children's lives annually. Human milk is enriched with VA (retinol) from the maternal blood, which originates from the hepatic reserve and dietary intake. Secreting retinol into milk will benefit the nursing infant through breast milk, but retaining retinol is also important for the maternal health. Previous studies found that the public health intervention of high-dose VA supplementation to lactating mothers did not significantly lower child mortality. The World Health Organization (WHO) recently acknowledged that our understanding about the principle of VA allocation within the maternal system and the secretion into milk is too incomplete to devise an effective intervention. METHODS: We present a secondary analysis of data collected among lactating mothers in VAD endemic northern Kenya (n = 171), examining nutritional, inflammatory, and ecological factors that might associate with maternal retinol allocation. Regression models were applied using the outcome milk-retinol allocation index: milk retinol/(milk retinol + serum retinol). RESULTS: Ten percent of the sample was identified as VAD. The average milk retinol concentration was 0.1 µmo/L, grossly below what is considered minimally necessary for an infant (1 µmol/L). VAD mothers and mothers with inflammation did not seem to compromise their milk retinol even though their serum retinol was lower than non-VAD and noninflammation mothers. Breast milk fat concentration positively correlated with milk retinol but not with serum retinol. CONCLUSIONS: This exploratory study contributes toward an understanding of maternal retinol allocation.

Hay fever, asthma, and eczema and early infectious diseases among children in Kilimanjaro, Tanzania.

OBJECTIVES: To investigate the hygiene (or "old friends") hypothesis in a high-infectious disease (ID) environment, rural Kilimanjaro, Tanzania. METHODS: Among a cross-sectional sample of 2- to 7-year-old children, we collected physician-diagnosed hay fever, asthma, and eczema, history of hospitalization, family size, and household environment information via questionnaire; performed active and passive surveillance for ID; and, evaluated total immunoglobulin E (IgE) and biomarkers of inflammation in dried blood spot specimens. We used regression models to describe patterns in allergic diseases. RESULTS: Complete information was available for 280 children: 12.5% had been diagnosed with hay fever; 18.9% with eczema; 2.1% with asthma. There was a positive association between hay fever and eczema diagnoses (π2 : 4.07; P = 0.044); total IgE was positively associated with eczema (ß: 0.24; P = 0.100) and allergic diseases together (ß: 0.26; P = 0.042). ID were common: the incidence of any ID diagnosis was 28 per 100 children per month. Hay fever was inversely associated with household animals (OR: 0.27; P = 0.006), and positively associated with earth housing materials (OR: 1.93; P = 0.079) and hospitalization in infancy with an ID (3.16; P = 0.066); patterns were similar when allergic disease outcomes were considered together. Few associations between these predictors and eczema or asthma alone were apparent. CONCLUSIONS: Allergic diseases were common among children in Kilimanjaro. The inverse association between household animals and allergy is consistent with the hygiene/old friends hypothesis; however, positive associations between allergic diseases and earth housing materials and early hospitalization with ID bear further explanation.

Nutrient intakes associated with elevated serum C-reactive protein concentrations in normal to underweight breastfeeding women in Northern Kenya.

OBJECTIVES: Low-grade elevation of C-reactive protein (CRP) is a non-specific inflammatory marker, used as a predictor for cardiovascular disease development and chronic inflammatory risks. Research investigating dietary influences on inflammation has focused primarily on the relationship between dietary characteristics, CRP elevation and BMI in the populations at greatest risk for cardiovascular disease, namely those in the overweight and obese ranges, often in clinical settings and/or among those middle aged or older, leaving little information about normal to underweight populations of reproductive age in ecological settings. This study evaluates impacts of dietary nutrients on serum CRP levels in a population of predominantly underweight to normal weight adult women experiencing the additional nutritional demands of lactation. METHODS: Data from non-overweight breastfeeding Ariaal women of Kenya collected in 2006 were used (n = 194). Logistic regression models were applied using low-grade CRP elevation (hsCRP > 3 mg/L) as the outcome variable and dietary nutrients, age, BMI, and serum retinol as predictors. RESULTS: Models showed that energy intake (Kcal) and age were positive predictors of CRP elevation while folate intake, total vitamin A intake, and serum retinol concentration were protective against CRP elevation. Unlike previous studies among higher BMI populations, this study found no significant effect of dietary lipids/fatty acids or BMI on CRP elevation. CONCLUSIONS: The effects of specific dietary nutrients on inflammatory status may vary with BMI or, in women, reproductive status. Further research should investigate the role of dietary fats, fatty acids, and antioxidant vitamins across populations with a wide range of BMI, including postpartum women.

Hemoglobin measurement in venous blood compared with pooled and single-drop capillary blood: a method-comparison study in a controlled and survey setting in Uganda among children and women.

BACKGROUND: Standard practice for estimating anemia in population-based surveys is to use a point-of-care device to measure hemoglobin (Hb) in a single drop of capillary blood. Emerging evidence points to larger than expected differences in Hb concentration depending on the blood source. OBJECTIVE: We evaluated use of different blood sources to measure Hb with a HemoCue 201+ analyzer compared with the reference method of venous blood tested with a Sysmex XN-450 hematology analyzer. METHODS: Hb concentration in venous, pooled capillary, and single-drop capillary blood were collected in controlled (laboratory) and survey (Demographic Health Survey-8 pilot) settings in Uganda among children 6-59 mo and nonpregnant women 15-49 y. Venous and capillary blood collected from the same individual was tested using a HemoCue 201+ analyzer and the venous blood was also measured with a Sysmex XN-450 hematology analyzer. Agreement between measures was estimated using Lin's concordance correlation coefficient, Bland-Altman plots, and Deming regression. Means and prevalences were compared using paired t-tests and McNemar's tests, respectively. RESULTS: The limits of agreement between Hb measured using a HemoCue 201+ analyzer and the reference method were lowest for venous (1.1-1.96 g/dL), followed by pooled capillary (1.45-2.27 g/dL), and single-drop capillary blood (2.23-3.41 g/dL). Mean differences were <0.5 g/dL across comparators. There were statistically significant differences in Hb concentration from both types of capillary blood. Anemia prevalence was lower in pooled capillary blood compared with the reference method. CONCLUSIONS: The variability of Hb measured by capillary blood using the HemoCue 201+ analyzer is higher than venous blood but the extent to which this impacts the validity of Hb and anemia estimates requires further exploration. Future research is also needed to evaluate the implications of using venous compared with capillary blood in population-based surveys. This trial was registered at clinicaltrials.gov (NCT05059457).

Clippers are superior to scissors in the collection of hair for chemical analysis in companion dogs: a Dog Aging Project preliminary study.

OBJECTIVE: To identify the safest, most efficient method for hair sample collection from companion dogs among clippers, scissors, and razors and to validate obtained samples with cortisol concentration analysis. ANIMALS: 25 healthy, privately owned dogs. METHODS: 2 hair samples were collected from each dog's ischiatic region with different implements (scissors, razors, or clippers). The collecting clinician completed a Hair Collection Questionnaire (HCQ) for each sample that compared subjective sample quality, time of collection, restraint needed, and patient experience. Each sample was evaluated by cortisol enzyme immunoassay. RESULTS: Clippers had higher overall HCQ scores than scissors, and scissors had higher HCQ scores than razors. Collection was faster for clippers than scissors, and scissors were faster than razors. There were no differences in sample quality between scissors and clippers, and sample quality was lower with razors. There was no difference in restraint needed or patient experience. Collection of long hair had higher HCQ scores than collection of medium and short hair. Collection of hair from dogs with an undercoat had higher HCQ scores than collection of hair from dogs without an undercoat. Dog size had no effect on HCQ score. Hair cortisol concentration did not vary between scissors or clippers (P = .111). Hair color and age did not affect hair cortisol concentration (P = .966 and P = .676, respectively). CLINICAL RELEVANCE: Clippers are recommended for hair sample collection from companion dogs. Scissors are an adequate alternative.

Predictors of delayed-type hypersensitivity to Candida albicans and anti-Epstein-Barr virus antibody among children in Kilimanjaro, Tanzania.

We evaluated sex, age, nutritional status, and infectious disease (ID) as predictors of two biomarkers of cell-mediated immunity (CMI), delayed-type hypersensitivity to Candida albicans (DTH-Candida), and anti-Epstein-Barr virus antibody (EBV Ab), among 200 children in Kilimanjaro, Tanzania. DTH-Candida, which decreases with compromised CMI, was positively associated with age (OR: 1.27; 95% CI: 1.02, 1.57) and triceps skinfold (TSF; OR: 1.16; 95% CI: 1.02, 1.26), and inversely associated with height-for-age Z score (HAZ; OR: 0.86; 95% CI: 0.68, 1.08) and diagnosed ID (OR: 0.48; 95% CI: 0.22, 1.08). There was significant interaction between TSF and ID: DTH-Candida exhibited a strong inverse association with ID among children with low TSF (OR: 0.16; 95% CI: 0.05, 0.50) and a strong positive association with TSF among children with ID (OR: 2.64; 95% CI: 1.29, 5.42). EBV Ab, which increases with compromised CMI, was inversely associated with male sex (ß: -0.47; 95% CI: -0.70, -0.24) and TSF (ß: -0.04; 95% CI: -0.08, 0.00), and positively associated with HAZ (ß: 0.06; 95% CI: -0.03, 0.15). Among males, EBV Ab was positively associated with anemia. Among normal HAZ children, EBV Ab was inversely associated with TSF. There was no association between DTH-Candida and EBV Ab. While DTH-Candida provides a direct measure of CMI, our results suggest that interpretation of EBV-Ab among Kilimanjaro children was complicated by its indirect relationship with CMI. Among our sample, CMI increased with age and adequate nutrition and was compromised during acute ID. The suggestive CMI-compromising effect of increasing height-for-age may bear further exploration.

Associations between childhood maltreatment and physiological dysregulation in adulthood: Methodological decisions and implications.

BACKGROUND: Childhood maltreatment is linked with health problems in adulthood. Theoretical models suggest that maltreatment leads to dysregulation in several bodily systems, and this has been corroborated using measures of physiological function (i.e., biomarkers). Methodological decisions involving the measurement of maltreatment and dimension reduction with respect to biomarkers (i.e., combining information across multiple measures) may influence research findings. OBJECTIVE: The present study compares associations between childhood maltreatment and adult physiological dysregulation using multiple dimension reduction approaches and measures of maltreatment. PARTICIPANTS AND SETTING: Participants were recruited, as children, to a prospective study of the correlates and consequences of childhood maltreatment. 253 participants were retained and provided biomarker data at midlife. Physiological dysregulation was operationalized with a conventional allostatic load approach and a novel statistical distance approach. METHODS: Regression models were employed with allostatic load or statistical distance as the outcome and prospectively or retrospectively measured child maltreatment as the primary predictor. RESULTS: When using allostatic load as the outcome, prospectively measured childhood maltreatment was positively associated with physiological dysregulation (b = 0.70, SE = 0.31, p = 0.02). When using statistical distance as the outcome, retrospectively measured childhood maltreatment was positively associated with physiological dysregulation (b = 0.69, SE = 0.19 p < 0.001). CONCLUSIONS: We report a positive association between childhood maltreatment and physiological dysregulation at midlife. However, the significance and magnitude of effects varied with different maltreatment and physiological dysregulation measures. Further review of the methods used to study adult health conditions and their relation to childhood maltreatment is needed.

Salivary concentration of progesterone and cortisol significantly differs across individuals after correcting for blood hormone values.

Between-individual variation of salivary progesterone (P4) and cortisol levels does not always closely reflect blood hormone concentrations. This may be partly a function of individual differences in salivary hormone excretion. We tested whether time of day at sampling and ethnicity contributed to individual variation in salivary hormones after adjusting for blood hormone levels. Forty-three Caucasian and 15 Japanese women (18-34 years) collected four sets of matched dried blood spot (DBS) and saliva specimens across a menstrual cycle (N = 232 specimen sets). Linear fixed-effects (LFE) models were used to estimate the effects of diurnal variation and ethnicity on salivary P4 and cortisol while adjusting for DBS levels. For each hormone, women with exclusively positive or negative residuals (unexplained variance) from the LFE models were categorized as high- or low-saliva-to-DBS hormone ratio (SDR; high or low salivary secretors), respectively. We found that salivary P4 (P < 0.05) was significantly higher in early morning compared to the afternoon, after controlling for DBS levels, ethnicity, and BMI. After further adjusting for this diurnal effect, significant individual variation in salivary P4 and cortisol remained: sixteen and nine women, respectively were categorized as low or high salivary secretors for both hormones (P < 0.001), suggesting systematic individual-specific variation of salivary hormonal concentration. We conclude that when saliva is used to quantify P4 or cortisol levels, time of day at sampling should be controlled. Even with this adjustment, salivary P4 and cortisol do not closely mirror between- individual variation of serum P4 and cortisol in a substantial proportion of individuals.

Sensitivity and specificity of C-reactive protein and α(1) -acid glycoprotein for episodes of acute infection among children in Kilimanjaro, Tanzania.

OBJECTIVES: Biomarkers of inflammation, including C-reactive protein (CRP) and α(1) -acid glycoprotein (AGP), have tremendous potential in anthropological, public health, and nutrition research as objective indicators of acute infection; however, their usage 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 (ID) episodes among children in the Kilimanjaro region of Tanzania. METHODS: Data were available from 43 3- to 5-year-old children. CRP and AGP were measured in capillary whole dried blood spots (DBS). Two-week morbidity history interviews with children's primary caregivers were used to detect recent episodes of acute ID. Specimens and morbidity history interviews were collected from each child on one (n = 13) or two (n = 30) occasions for 73 paired interviews and specimens. RESULTS: 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%. CONCLUSIONS: Among children in Kilimanjaro, Tanzania, assessed in whole blood stored as DBS, 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.

Validation of a new multiplex assay against individual immunoassays for the quantification of reproductive, stress, and energetic metabolism biomarkers in urine specimens.

UNLABELLED: 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. OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Multiplexed micronutrient, inflammation, and malarial antigenemia assessment using a plasma fractionation device.

Processing and storing blood samples for future analysis of biomarkers can be challenging in resource limited environments. The preparation of dried blood spots (DBS) from finger-stick collection of whole blood is a widely used and established method as DBS are biosafe, and allow simpler field processing, storage, and transport protocols than serum or plasma. Therefore, DBS are commonly used in population surveys to assess infectious disease and/or micronutrient status. Recently, we reported that DBS can be used with the Q-plex™ Human Micronutrient 7-plex Array (MN 7-plex), a multiplexed immunoassay. This tool can simultaneously quantify seven protein biomarkers related to micronutrient deficiencies (iodine, iron and vitamin A), inflammation, and malarial antigenemia using plasma or serum. Serum ferritin, an iron biomarker, cannot be measured from DBS due to red blood cell (RBC) ferritin content confounding the results. In this study, we assess a simple blood fractionation tool that passively separates plasma from other blood components via diffusion through a membrane into a plasma collection disc (PCD). We evaluated the concordance of MN 7-plex analyte concentrations from matched panels of eighty-eight samples of PCD, DBS, and wet plasma prepared from anticoagulated venous whole blood. The results showed good correlations of >0.93 between the eluates from PCD and DBS for each analyte except ferritin; while correlations seen for plasma/PCD were weaker. However, the recovery rate of the analytes from the PCD were better than those from DBS. The serum ferritin measures from the PCD were highly correlated to wet plasma samples (0.85). This suggests that surveillance for iron status in low resource settings can be improved over the current methods restricted to only measuring sTfR in DBS. When used in combination with the MN 7-plex, all seven biomarkers can be simultaneously measured using eluates from the PCDs.

Mineral Nutrition of Samburu Adolescents: A Comparative Study of Pastoralist Communities in Kenya.

Objectives: This study aimed to characterize mineral nutrition (copper, magnesium, selenium, and zinc) in Samburu pastoralist youth, in the context of differential cultural transitions due to uneven changes in educational access, herding intensity, polygyny, and access to wild, domesticated, and market-sourced foods. Materials and Methods: Whole dried blood spots were collected in a total of 161 youth (highlands, n = 97; lowlands, n = 64) to assess concentrations of: cadmium, copper, lead, magnesium, mercury, selenium, and zinc. Concentrations were determined through Inductively Coupled Mass Spectrometry. Dietary intakes were assessed by 24-hour recall method and calculation of probability of inadequate intakes. WHO protocols were applied to collect anthropometric measures in the youth. Results: Nearly half of the adolescents (47.8%) fell below the reference range for zinc status, and 88.2% had low zinc-to-copper ratios. High probability of nutrient inadequacies were evident for protein, fat, vitamins A, B12, C, and E. In generalized linear modeling, lowland residence was negatively associated with zinc status and the zinc-to-copper ratio, and positively correlated with selenium and copper status. Other significant correlates were: dairy livestock ownership; wife number of the youth's mother; meat consumption; vegetable consumption; protein intake; infectious disease morbidities; BMI; and hemoglobin concentrations. Discussion: In recent decades, Samburu pastoralists of northern Kenya have experienced marked dietary changes in the context of market integration, extreme drought, diminishing pasture availability, and violent civil conflict. Some children (particularly boys) successfully supplement their diets by foraging for wild foods, while others (particularly actively herding girls) may be more vulnerable.

SARS-CoV-2 specific antibody trajectories in mothers and infants over two months following maternal infection.

Infants exposed to caregivers infected with SARS-CoV-2 may have heightened infection risks relative to older children due to their more intensive care and feeding needs. However, there has been limited research on COVID-19 outcomes in exposed infants beyond the neonatal period. Between June 2020 - March 2021, we conducted interviews and collected capillary dried blood spots from 46 SARS-CoV-2 infected mothers and their infants (aged 1-36 months) for up to two months following maternal infection onset (COVID+ group, 87% breastfeeding). Comparative data were also collected from 26 breastfeeding mothers with no known SARS-CoV-2 infection or exposures (breastfeeding control group), and 11 mothers who tested SARS-CoV-2 negative after experiencing symptoms or close contact exposure (COVID- group, 73% breastfeeding). Dried blood spots were assayed for anti-SARS-CoV-2 S-RBD IgG and IgA positivity and anti-SARS-CoV-2 S1 + S2 IgG concentrations. Within the COVID+ group, the mean probability of seropositivity among infant samples was lower than that of corresponding maternal samples (0.54 and 0.87, respectively, for IgG; 0.33 and 0.85, respectively, for IgA), with likelihood of infant infection positively associated with the number of maternal symptoms and other household infections reported. COVID+ mothers reported a lower incidence of COVID-19 symptoms among their infants as compared to themselves and other household adults, and infants had similar PCR positivity rates as other household children. No samples returned by COVID- mothers or their infants tested antibody positive. Among the breastfeeding control group, 44% of mothers but none of their infants tested antibody positive in at least one sample. Results support previous research demonstrating minimal risks to infants following maternal COVID-19 infection, including for breastfeeding infants.

The effects of a long-term psychosocial stress on reproductive indicators in the baboon.

Psychosocial stress is thought to negatively impact fecundity, but human studies are confounded by variation in nutrition and lifestyle. Baboons offer a useful model to test the effect of prolonged mild stress on reproductive indicators in a controlled setting. Following relocation from social groups to solitary housing, a previously documented stressful event for nonhuman primates, daily urine samples, tumescence, and menstrual bleeding were monitored in twenty baboons (Papio sp.) for 120-150 days. Specimens were assayed for estrone conjugates (E1C), pregnanediol-3-glucuronide (PDG), follicle-stimulating hormone (FSH), and cortisol. Linear mixed effects models examined (1) the effects of stress on frequency of anovulation, hormone levels, tumescence and cycle length, and (2) the relationship of cortisol with reproductive indicators. Despite cortisol levels indicative of stress, anovulation was negligible (1% in 102 cycles). PDG, FSH, cycle length, and tumescence declined during the first four cycles, but began recovery by the fifth. Cortisol was negatively associated with FSH but not associated with PDG, E1C or tumescence. Ovulation, E1C, and luteal phase length were not affected. Tumescence tracked changes in FSH and PDG, and thus may be a useful indicator of stress on the reproductive axis. Elevated cortisol was associated with reduced FSH, supporting a model of cortisol action at the hypothalamus rather than the gonad. After four to five menstrual cycles the reproductive indicators began recovery, suggesting adjustment to new housing conditions. In conclusion, individual housing is stressful for captive baboons, as reflected by cortisol and reproductive indicators, although ovulation, a relatively direct proxy for fecundity, is unaffected.

Vitamin A dynamics in breastmilk and liver stores: a life history perspective.

OBJECTIVES: Newborns are dependent on breastmilk vitamin A for building hepatic stores of vitamin A that will become critical for survival after weaning. It has been documented that vitamin A concentrations in breastmilk decline across the first year postpartum in both well-nourished and malnourished populations. The reason for this decline has been assumed to be a sign of concurrently depleting maternal hepatic stores. This study investigates this assumption to clarify why the decline occurs, drawing on life history theory. METHODS: A cross sectional survey was conducted among lactating mothers in Kenya in 2006. Data were used to examine (1) the relationship between liver vitamin A and time, (2) if the relationship between milk and liver vitamin A varies by time, and (3) by maternal parity. RESULTS: The relationship between liver vitamin A and time fits the quadratic pattern with marginal significance (P = 0.071, n = 192); the liver vitamin A declined during early postpartum then recovered in late postpartum time, controlling covariates. The milk-liver vitamin A relationship varied by postpartum time periods (P = 0.03) and by maternal parity (P = 0.005). Mothers in earlier postpartum or higher parity had a stronger positive relationship between milk and liver vitamin A than mothers in later postpartum or lower parity. CONCLUSIONS: Our observations are consistent with life history tradeoffs and negate the assumption that maternal hepatic and milk vitamin A decline together. Rather, maternal liver vitamin A has a dynamic relationship with milk vitamin A, particularly depending on postpartum time and maternal parity.