Hormone measures in finger-prick blood spot samples: new field methods for reproductive endocrinology

Cord Blood Adductomics Reveals Oxidative Stress Exposure Pathways of Bronchopulmonary Dysplasia

Fetal and neonatal exposures to perinatal oxidative stress (OS) are key mediators of bronchopulmonary dysplasia (BPD). To characterize these exposures, adductomics is an exposure science approach that captures electrophilic addition products (adducts) in blood protein. Adducts are bound to the nucleophilic cysteine loci of human serum albumin (HSA), which has a prolonged half-life. We conducted targeted and untargeted adductomics to test the hypothesis that adducts of OS vary with BPD. We studied 205 preterm infants (≤28 weeks) and 51 full-term infants from an ongoing birth cohort. Infant plasma was collected at birth (cord blood), 1-week, 1-month, and 36-weeks postmenstrual age. HSA was isolated from plasma, trypsin digested, and analyzed using high-performance liquid chromatography-mass spectrometry to quantify previously annotated (known) and unknown adducts. We identified 105 adducts in cord and postnatal blood. A total of 51 known adducts (small thiols, direct oxidation products, and reactive aldehydes) were increased with BPD. Postnatally, serial concentrations of several known OS adducts correlated directly with supplemental oxygen exposure. The application of large-scale adductomics elucidated OS-mediated pathways of BPD. This is the first study to investigate the "neonatal-perinatal exposome" and to identify oxidative stress-related exposure biomarkers that may inform antioxidant strategies to protect the health of future generations of infants.

Three common assumptions about inflammation, aging, and health that are probably wrong

Chronic inflammation contributes to the onset and progression of cardiovascular disease and other degenerative diseases of aging. But does it have to? This article considers the associations among inflammation, aging, and health through the lens of human population biology and suggests that chronic inflammation is not a normal nor inevitable component of aging. It is commonly assumed that conclusions drawn from research in affluent, industrialized countries can be applied globally; that aging processes leading to morbidity and mortality begin in middle age; and that inflammation is pathological. These foundational assumptions have shifted focus away from inflammation as a beneficial response to infection or injury and toward an understanding of inflammation as chronic, dysregulated, and dangerous. Findings from community-based studies around the world-many conducted in areas with relatively high burdens of infectious disease-challenge these assumptions by documenting substantial variation in levels of inflammation and patterns of association with disease. They also indicate that nutritional, microbial, and psychosocial environments in infancy and childhood play important roles in shaping inflammatory phenotypes and their contributions to diseases of aging. A comparative, developmental, and ecological approach has the potential to generate novel insights into the regulation of inflammation and how it relates to human health over the life course.

Minimally invasive biomarkers in human and non-human primate evolutionary biology: Tools for understanding variation and adaptation

BACKGROUND

The use of minimally invasive biomarkers (MIBs - physiological biomarkers obtained from minimally invasive sample types) has expanded rapidly in science and medicine over the past several decades. The MIB approach is a methodological strength in the field of human and non-human primate evolutionary biology (HEB). Among humans and our closest relatives, MIBs provide unique opportunities to document phenotypic variation and to operationalize evolutionary hypotheses.

AIMS

This paper overviews the use of MIBs in HEB. Our objectives are to (1) highlight key research topics which successfully implement MIBs, (2) identify promising yet under-investigated areas of MIB application, and (3) discuss current challenges in MIB research, with suggestions for advancing the field.

DISCUSSION AND CONCLUSIONS

A range of MIBs are used to investigate focal topics in HEB, including energetics and life history variation/evolution, developmental plasticity, and social status and dominance relationships. Nonetheless, we identify gaps in existing MIB research on traits such as physical growth and gut function that are central to the field. Several challenges remain for HEB research using MIBs, including the need for additional biomarkers and methods of assessment, robust validations, and approaches that are standardized across labs and research groups. Importantly, researchers must provide better support for adaptation and fitness effects in hypothesis testing (e.g., by obtaining complementary measures of energy expenditure, demonstrating redundancy of function, and performing lifetime/longitudinal analyses). We point to continued progress in the use of MIBs in HEB to better understand the past, present, and future of humans and our closest primate relatives.

Applying minimally invasive biomarkers of chronic stress across complex ecological contexts

Chronic stress is both theoretically and methodologically challenging to operationalize through biomarkers. Yet minimally invasive, field-friendly biomarkers of chronic stress are valuable in research linking biology and culture, seeking to understand differential patterns of human development across ecological contexts, and exploring the evolution of human sociality. For human biologists, a central question in measurement and interpretation of biomarkers is how stress-responsive physiological systems are regulated across diverse human ecologies. This article aims to describe a conditional toolkit for human biologists interested in the study of chronic stress, highlighting a mix of longstanding and novel biomarkers, with special focus on hair/fingernail cortisol, latent herpesvirus antibodies, allostatic load indices, and serial/ambulatory data collection approaches. Future trends in chronic stress biomarker research, including epigenetic approaches, are briefly considered. This overview considers: (1) challenges in separating a distinctly psychosocial dimension of chronic stress from adversity more broadly; (2) essential characteristics of human ecology that shape interpretation; (3) retrospective vs. longitudinal sampling; (4) the role of age, developmental effects, and local biologies; (5) different timescales of chronicity; and (6) the role of culture.

Psychosocial stress and ovarian function in adolescent and young adult cancer survivors

STUDY QUESTION

Is psychosocial stress associated with ovarian function in reproductive-aged survivors of cancer diagnosed as adolescents and young adults (AYA survivors)?

SUMMARY ANSWER

We observed no association between self-reported and biomarkers of psychosocial stress and ovarian function in AYA survivors.

WHAT IS KNOWN ALREADY

Psychosocial stress suppresses hypothalamic-pituitary-ovarian axis, resulting in ovulatory dysfunction, decreased sex steroidogenesis and lower fertility in reproductive-aged women. Many cancer survivors experience high psychosocial stress and hypothalamic-pituitary-adrenal axis dysregulation. The menstrual pattern disturbances and infertility they experience have been attributed to ovarian follicle destruction, but the contribution of psychosocial stress to these phenotypes is unknown.

STUDY DESIGN, SIZE, DURATION

A cross-sectional study was conducted estimating the association between perceived stress, measured by self-report and saliva cortisol, and ovarian function, measured by bleeding pattern, dried blood spot (DBS) FSH and LH, and saliva estradiol. We included 377 AYA survivor participants.

PARTICIPANTS/MATERIALS, SETTING, METHODS

AYA survivor participants were ages 15-35 at cancer diagnosis and ages 18-40 at study enrollment, had completed primary cancer treatment, had a uterus and at least one ovary, did not have uncontrolled endocrinopathy and were not on hormone therapy. Recruited from cancer registries, physician referrals and cancer advocacy groups, participants provided self-reported information on psychosocial stress (Perceived Stress Scale-10 (PSS-10)) and on cancer and reproductive (fertility, contraception, menstrual pattern) characteristics. DBS samples were collected timed to the early follicular phase (cycle Days 3-7) for menstruating individuals and on a random day for amenorrheic individuals; saliva samples were collected three time points within 1 day. FSH and LH were measured by DBS ELISAs, cortisol was measured by ELISA and estradiol was measured by liquid chromatography tandem mass spectrometry.

MAIN RESULTS AND THE ROLE OF CHANCE

The median age of participants was 34.0 years (range 19-41) at a median of 6.0 years since cancer diagnosis. The most common cancer was breast (32.1%). Median PSS-10 score was 15 (range 0-36), with 5.3% scoring ≥26, the cut point suggestive of severe stress. Cortisol levels followed a diurnal pattern and cortisol AUC was negatively correlated with PSS-10 scores (P = 0.03). Neither PSS-10 scores nor cortisol AUC were associated with FSH, LH, estradiol levels or menstrual pattern. Waking and evening cortisol and the cortisol awakening response also were not related to ovarian function measures.

LIMITATIONS, REASONS FOR CAUTION

Our analysis is limited by its cross-sectional nature, heterogeneity of cancer diagnosis and treatments and low prevalence of severe stress.

WIDER IMPLICATIONS OF THE FINDINGS

The lack of association between psychosocial stress and a variety of ovarian function measures in female AYA cancer survivors suggests that psychosocial stress does not have a significant impact on the reproductive axis of AYA survivors. This finding is important in counseling this population on their menstrual pattern and family building plans.

STUDY FUNDING/COMPETING INTEREST(S)

NIH HD080952, South Korea Health Industry Development Institute HI18C1837 (JK). Dr A.D. works for Bluebird Bio, Inc., Dr D.Z. works for ZRT Labs and Dr P.M.S. works for Ansh Labs, which did not sponsor, support or have oversight of this research. Other authors report no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

The Nutritional Status of Individuals Adopted Internationally as Children: A Systematic Review

Since 1955, international adoption has been a way of finding homes for children who have been orphaned or abandoned. We aimed to describe the nutritional status of individuals adopted internationally and their long-term nutritional and health outcomes. We searched four databases for articles published from January 1995 to June 2020, which included information on anthropometric or micronutrient status of children adopted internationally (CAI). Mean Z-scores on arrival to adoptive country ranged from -2.04 to -0.31 for weight for age; -0.94 to 0.39 for weight for height; -0.7 to 0 for body mass index; -1.89 to -0.03 for height for age; -1.43 to 0.80 for head circumference for age. Older children, those adopted from institutionalized care or with underlying disability, were more likely to be malnourished. Though long-term data was scarce, mean Z-scores post-adoption ranged from -0.59 to 0.53 for weight for age; -0.31 to 1.04 for weight for height; 0.39 to 1.04 for body mass index; -1.09 to 0.58 for height for age; -0.06 to 1.23 for head circumference for age. We conclude that though CAI are at high risk of malnutrition at baseline, marked catch-up growth is possible, including for those older than two years of age on arrival. This has implications not only for CAI but for the wider population of malnourished children worldwide. Research on how to optimize catch-up growth is a priority.

Reproductive hormone measurement from minimally invasive sample types: Methodological considerations and anthropological importance

Energetic investment in human reproduction has long been recognized as costly, influencing developmental, physiological, and behavioral patterns in males and females. These effects are largely coordinated through the actions of reproductive hormones (eg, testosterone, estradiol, and progesterone). Here, the utility and limitations of minimally invasive sampling techniques are explored, providing a novel perspective on how reproductive hormone measurements can enhance reproductive endocrinology research. Salivary steroid measures are most commonly used, although several dried blood spot and urine assays are also available, and researchers continue to explore the efficacy of other sample types. These relatively simple measures have facilitated the collection of multiple samples from a single participant, allowing researchers to more accurately track the diurnal and cyclical variation exhibited by many reproductive hormones. Ultimately, the ability to collect fine-grained participant data allows biological anthropologists to better test questions central to human reproductive ecology, life history theory, and public health. For example, fieldwork using these techniques suggests that testosterone profile variation across populations is influenced by energetic constraints and reproductive status. Moreover, hormone concentrations shape the development of sex characteristics, with implications for evolutionary questions related to sexual selection. Hormone levels also can be used to identify a range of medical concerns (eg, suppressed hormone production levels linked with psychosocial stress). These findings highlight how minimally invasive collection techniques can be applied to test diverse evolutionary hypotheses and identify important health concerns. Still, more work is needed to standardize collection and laboratory analysis procedures, thereby enabling more direct data comparisons between researchers.

Field methods and strategies for assessing female reproductive functioning

A detailed understanding of female reproductive functioning is important to many disciplines including anthropology, evolutionary theory, demography, psychology, and biomedicine. In this article, I describe strategies and methods that have been used successfully in community-based studies of human reproduction, many in remote locales, to produce high quality biomarker data. These techniques are applicable to a wide range of research questions and populations, and to persons from adolescence through senescence. I give particular attention to the inherent challenges imposed by the cyclical and somewhat unpredictable nature of the hypothalamic-pituitary-ovarian axis including the necessity and difficulty of ascertaining the timing and occurrence of ovulation, the limits of different sampling regimes for capturing fluctuations in reproductive hormones, and the critical importance of recognizing and, when possible, reducing selection bias. I discuss the relative advantages and disadvantages of collecting saliva, urine, and dried blood spots, and describe some of the subtleties involved in collecting contamination-free samples. Once samples are collected, they must be stored in a manner that minimizes degradation; I describe techniques to keep samples cold even without access to electricity or dry ice. I also discuss various issues that should be considered during initial discussions with a laboratory and when samples are assayed by the laboratory. I include examples of techniques that have worked well in actual field studies, and examples of flawed analytical approaches that should be avoided. With these and other tools, even under technology-sparse conditions, researchers can investigate variability in human physiology across the breadth of human habitats.

Do documented records and retrospective reports of childhood maltreatment similarly predict chronic inflammation?

BACKGROUND

Childhood adversities have been associated with chronic inflammation and risk for cardiovascular disease. With some exceptions, existing knowledge of this relationship is based on retrospective self-reports, potentially subject to recall bias or memory problems. We seek to determine whether childhood maltreatment is associated with higher C-reactive protein (CRP) later in life and whether individuals with official and retrospective self-reports of maltreatment and men and women show similar increases in risk.

METHODS

Data are from in-person interviews in 2009-2010 with 443 offspring (mean age = 23.4) of parents in a longitudinal study of the consequences of childhood maltreatment. Official reports of maltreatment were abstracted from 2011-2013 Child Protective Services records. Eleven measures were used to assess self-reported maltreatment retrospectively. Seventeen percent of offspring had official reports, whereas self-reported prevalence rates ranged from 5.4% to 64.8%. CRP was assessed through blood spot samples. Regression models were used to estimate the effect of maltreatment on inflammation, adjusting for age, sex, race, parent occupational status, current depression, smoking, and heavy drinking.

RESULTS

Individuals with official reports of child maltreatment and, specifically, physical abuse, had significantly higher levels of CRP than non-maltreated individuals. Maltreated females showed elevated CRP, independent of control variables, whereas no significant association was observed in males. Retrospective self-report measures of child maltreatment did not predict elevated CRP.

CONCLUSIONS

Individuals with documented histories of childhood maltreatment are at increased risk for chronic inflammation and may benefit from targeted interventions. The results strengthen inferences about the effects of childhood maltreatment on inflammation in females.

Fluispotter, a novel automated and wearable device for accurate volume serial dried blood spot sampling

Aim: A novel automated serial dried blood spot (DBS) sampler, 'Fluispotter', was tested for its sampling performance. Materials & methods: An LC-MS/MS method was developed for the analysis of cortisol in DBS samples serially spotted by Fluispotter. The cortisol concentrations in 148 paired DBS and plasma samples were compared across a hematocrit (HCT) range of 22-55%. Results: The interassay accuracy and precision were <10%. Overall assay bias was negligible across the HCTs tested when analyzing the whole-spot DBS samples. The accuracy and precision of the blood volume in 10 μl DBS samples spotted by Fluispotters and micropipettes were within 3%. Deming regression and Bland-Altman analysis showed a good agreement of DBS-predicted and measured plasma cortisol. Conclusion: The Fluispotter performed serial sampling with high accuracy and precision of the sample blood volume.

Early Pubertal Timing and Testosterone Associated With Higher Levels of Adolescent Depression in Girls

OBJECTIVE

The prevalence of depression increases dramatically during puberty in girls. Earlier work in this sample reported that the sex steroids estradiol and testosterone were associated with increased depression in girls. Using three additional data waves (983 new observations), we retest the relative contributions of pubertal timing, pubertal status, and sex hormones on the increases in female depression.

METHOD

Eight waves of data from the prospective, representative Great Smoky Mountains Study were used covering female participants in the community who were 9 to 16 years of age (3,005 assessments of 630 girls; 1993-2000). Structured interviews assessed depressive disorders. Youth rated their pubertal status using Tanner stage drawings, and sex steroids were assayed from dried blood spots.

RESULTS

Risk for depression during puberty was associated with both age and Tanner stage in univariate models. In adjusted models accounting for pubertal timing and sex steroids, the apparent effects of age and Tanner stage were attenuated both in terms of statistical significance and effect size. The only significant predictors of change in depression status during puberty were early pubertal timing (odds ratio = 5.8, 95% CI = 1.9-17.9, p = .002 after age 12 years) and higher testosterone levels (odds ratio = 2.0, 95% CI = 1.1-3.8, p = .03 for quartile-split variable).

CONCLUSION

The added observations have modified the original conclusions, implicating the following: testosterone only, but not estradiol; and early pubertal timing, but not age or pubertal status per se. These findings argue for multiple pubertal determinants of depression risk, including factors that are socially and biologically mediated.

How and when to use dried blood spots in psychoneuroendocrinological research

OBJECTIVE

The term "dried blood spot" (DBS) refers to a sampling technique in which capillary whole blood is spotted on filter paper. Given the possibility to determine a wide range of hormones and related biomarkers in DBS, the method should be of interest to researchers in psychoneuroendocrinology. So far, however, the how and when of using DBS in this context have not been outlined.

METHODS

A review of the literature was conducted in order to describe the materials and procedures necessary to determine relevant biological markers from DBS (how to use DBS). In addition, a comparison of the DBS method with other sampling techniques was undertaken and examples of its previous use in psychoneuroendocrinology were provided (when to use DBS).

RESULTS

Both dyadic and DBS self-sampling are feasible, and a number of protocols are available to determine endocrine and immune, genetic and epigenetic markers. Decisions to use DBS instead of venous blood or saliva sampling should mainly be guided by whether it is sensible and feasible to determine the parameter of interest in whole blood obtained from DBS. In addition, DBS are well suited for large study populations with specific vulnerabilities, and for remotely located studies with budgetary constraints.

CONCLUSION

Dried blood spots are a promising material as well as a simple sampling technique for psychoneuroendocrinological research. Future efforts should be directed at continuing to adapt existing serum and plasma analysis protocols for use with DBS, and at testing the feasibility of DBS self-sampling in field studies.

Chronic noise exposure in the spontaneously hypertensive rat

Introduction:

Epidemiological studies have suggested an association between the relative risk for developing cardiovascular disease (CVD) and long-term exposure to elevated levels of transportation noise. The contention is that this association is largely owing to an increase in stress-related biomarkers that are thought to be associated with CVD. Animal models have demonstrated that acute noise exposure is capable of triggering a stress response; however, similar studies using chronic noise models are less common.

Materials and Methods:

The current study assessed the effects of intermittent daily exposure to broadband 80 kHz bandwidth noise of 87.3 dBA for a period of 21 consecutive days in spontaneously hypertensive rats.

Results:

Twenty-one days of exposure to noise significantly reduced body weight relative to the sham and unhandled control groups; however, noise had no statistically significant impact on plasma adrenocorticotropic hormone (or adrenal gland weights). Noise was associated with a significant, albeit modest, increase in both corticosterone and aldosterone concentrations following the 21 days of exposure. Interleukin 1 and interleukin 6 levels were unchanged in the noise group, whereas both tumour necrosis factor alpha and C-reactive protein were significantly reduced in noise exposed rats. Tail blood sampling for corticosterone throughout the exposure period showed no appreciable difference between the noise and sham exposed animals, largely due to the sizeable variation for each group as well as the observed fluctuations over time.

Discussion:

The current pilot study provides only modest support that chronic noise may promote stress-related biological and/or developmental effects. More research is required to verify the current findings and resolve some of the unexpected observations.

Psychobiological Factors of Sexual Functioning in Aging Women - Findings From the Women 40+ Healthy Aging Study

Background: A variety of biological and psychosocial factors are associated with women’s sexual health in midlife and older age. Evidence suggests a decline in sexual functioning in the context of aging and the menopausal transition, including changes in sexual desire, arousal, lubrication, orgasm, pain, and/or contentment. However, not all women in midlife and older age experience such a decline, and it remains unclear how the endocrine environment and psychosocial aspects contribute to the maintenance of healthy sexual functioning. Therefore, the aim of this study was to examine psychobiological predictors of sexual functioning in healthy middle-aged and elderly females.

Methods: A total of 93 healthy, sexually active women aged 40–73 years completed a battery of validated psychosocial questionnaires, including measures of sexual functioning (Female Sexual Function Index) and of protective psychological traits and interpersonal variables. The steroid hormones estrogen, testosterone, progesterone and dehydroepiandrosterone sulfate were determined in saliva samples, while follicle-stimulating hormone, luteinizing hormone and sex hormone-binding globulin were determined in dried blood spots. The findings were statistically adjusted for multiple testing.

Results: Age and postmenopausal status were negatively associated with overall sexual functioning, arousal, and lubrication. Regression analyses revealed that relationship satisfaction, emotional support, self-esteem, optimism, and life satisfaction each significantly predicted overall sexual functioning or specific aspects of sexual functioning, including arousal, contentment, orgasm, and pain (all p < 0.029). For desire and lubrication, no associations were found with the tested psychosocial factors. In terms of steroid hormones, testosterone was positively linked to orgasm (p = 0.012). In this sample, 79.6% reported to have healthy sexual functioning according to the questionnaires’ cutoff. Younger age (OR = 0.911, 95% CI 0.854–0.970, p = 0.004) and a higher level of emotional support (OR = 1.376, 95% CI 1.033–1.833, p = 0.029) were associated with the presence of healthy sexual functioning.

Discussion: Although aging and menopause negatively affected aspects of sexual functioning, the accompanying endocrine correlates were not predictive for sexual functioning in this healthy sample of middle-aged and older females. Instead, our findings suggest that sexual functioning is highly dependent on psychosocial aspects related to well-being. Accordingly, personality traits such as optimism, and interpersonal aspects such as emotional support and relationship satisfaction were identified as important predictors of sexual functioning.

Longitudinal Validity and Reliability of Brief Smartphone Self-Monitoring of Diet, Stress, and Physical Activity in a Diverse Sample of Mothers

BACKGROUND

Multiple strategies can be used when self-monitoring diet, physical activity, and perceived stress, but no gold standards are available. Although self-monitoring is a core element of self-management and behavior change, the success of mHealth behavioral tools depends on their validity and reliability, which lack evidence. African American and Latina mothers in the United States are high-priority populations for apps that can be used for self-monitoring of diet, physical activity, and stress because the body mass index (BMI) of mothers typically increases for several years after childbirth and the risks of obesity and its' sequelae diseases are elevated among minority populations.

OBJECTIVE

To examine the intermethod reliability and concurrent validity of smartphone-based self-monitoring via ecological momentary assessments (EMAs) and use of daily diaries for diet, stress, and physical activity compared with brief recall measures, anthropometric biomeasures, and bloodspot biomarkers.

METHODS

A purposive sample (n=42) of primarily African American (16/42, 39%) and Latina (18/42, 44%) mothers was assigned Android smartphones for using Ohmage apps to self-monitor diet, perceived stress, and physical activity over 6 months. Participants were assessed at 3- and 6-month follow-ups. Recall measures included brief food frequency screeners, physical activity assessments adapted from the National Health and Nutrition Examination Survey, and the nine-item psychological stress measure. Anthropometric biomeasures included BMI, body fat, waist circumference, and blood pressure. Bloodspot assays for Epstein-Barr virus and C-reactive protein were used as systemic load and stress biomarkers. EMAs and daily diary questions assessed perceived quality and quantity of meals, perceived stress levels, and moderate, vigorous, and light physical activity. Units of analysis were follow-up assessments (n=29 to n=45 depending on the domain) of the participants (n=29 with sufficient data for analyses). Correlations, R2 statistics, and multivariate linear regressions were used to assess the strength of associations between variables.

RESULTS

Almost all participants (39/42, 93%) completed the study. Intermethod reliability between smartphone-based EMAs and diary reports and their corresponding recall reports was highest for stress and diet; correlations ranged from .27 to .52 (P<.05). However, it was unexpectedly low for physical activity; no significant associations were observed. Concurrent validity was demonstrated for diet EMAs and diary reports on systolic blood pressure (r=-.32), C-reactive protein level (r=-.34), and moderate and vigorous physical activity recalls (r=.35 to.48), suggesting a covariation between healthy diet and physical activity behaviors. EMAs and diary reports on stress were not associated with Epstein-Barr virus and C-reactive protein level. Diary reports on moderate and vigorous physical activity were negatively associated with BMI and body fat (r=-.35 to -.44, P<.05).

CONCLUSIONS

Brief smartphone-based EMA use may be valid and reliable for long-term self-monitoring of diet, stress, and physical activity. Lack of intermethod reliability for physical activity measures is consistent with prior research, warranting more research on the efficacy of smartphone-based self-monitoring of self-management and behavior change support.

The influence of pubertal maturation on antisaccade performance

Adolescence is a period characterized by continued improvements in inhibitory control, and this persisting immaturity is believed to interact with affective/motivational behavior to generate the impulsive and risk-taking behavior evidenced at this time. Puberty is a central event of adolescence that has been shown to influence affective/motivational behavior. However, despite plausible mechanisms by which puberty might influence inhibitory control, researchers have yet to test this possibility rigorously. Thus, we designed a study to examine the unique role of pubertal maturation, independent of age, in the development of inhibitory control. In order to minimize age-related variability while maximizing pubertal status variability, we recruited 78 participants (34 F) whose ages narrowly spanned the mean age of gonadarche for each sex (F: ages 11-13, M: ages 12-14). Two complementary measures were used to assess pubertal status: (1) circulating blood serum testosterone and estradiol levels reflecting internal manifestations of pubertal maturation, and (2) Tanner staging by a trained nurse reflecting pubertal maturation's external manifestations. Inhibitory control was assessed using the antisaccade task, and findings were adjusted for the potential effect of age. Results revealed no association between testosterone levels and error rates or response latencies in either sex. In girls, estradiol levels were not associated with error rates, but were associated with faster response latencies. There was similarly no association between Tanner status and error rates, although girls in more advanced pubertal stages showed faster response latencies. Power analyses indicate that findings of a lack of association did not reflect limited statistical power. Thus, in a study designed to isolate the effects of pubertal maturation independent of age, both external and internal indices of pubertal maturation converged to indicate that age-related improvements in cold antisaccade performance are independent of pubertal maturation.

The Role of Blood Spot Dehydroepiandrosterone Sulfate Levels in Adjunct to Hand Wrist Radiographs as Skeletal Maturity Indicator

Objective

The purpose of this study was to find out whether blood spot Dehydroepiandrosterone Sulfate (DHEAs) levels can be used as Skeletal Maturity Indicators (SMI) by correlating them to hand-wrist maturation stages.

Methods

The cross sectional study population consisted of 107 subjects (62 females and 45 males) 5-25 years old. Hand-wrist radiographs were obtained, and the subjects were divided into 5 groups based on the hand-wrist skeletal maturity stages. A blood spot sample was collected and immunoassayed for DHEAs. Analysis of variance was used to compare the mean DHEAs levels corresponding to the hand-wrist maturation stages. Pearson's correlations were performed to determine the DHEAs trends relating to the various hand-wrist maturation stages.

Results

DHEAs levels increased continuously from the prepubertal stage to the acceleration, high growth velocity/peak, deceleration, and postpubertal stages (r=0.17), but the total increase was not found to be statistically significant (p=0.08).

Conclusion

The blood spot DHEAs level cannot be used as an SMI in individuals. Nevertheless, it can be used in conjunction with hand wrist radiographs to predict and validate the skeletal maturation. The role of DHEAs in the termination of growth and residual growth may be a subject for further research.

Self-collected dried blood spots as a tool for measuring ovarian reserve in young female cancer survivors

STUDY QUESTION

Are female young cancer survivors (YCS) able to self-collect high-quality dried blood spots (DBSs) at home to provide biospecimens for studying ovarian reserve?

SUMMARY ANSWER

YCS can self-collect high-quality DBS specimens in non-clinical settings, and anti-Mullerian hormone (AMH) levels can be assayed in such specimens.

WHAT IS KNOWN ALREADY

Large-scale biosample collection is a barrier to studying ovarian reserve in YCS. DBS collected by research personnel has high acceptability. AMH levels measured in DBS are highly correlated with those measured by serum-based methods.

STUDY DESIGN, SIZE, DURATION

In a prospective cohort study, YCS were recruited to self-collect DBS samples. AMH levels were assayed in 112 samples.

PARTICIPANTS/MATERIALS, SETTING, METHODS

YCS participants, ages 18-44, were recruited from a nationwide longitudinal cohort and DBS collection materials were posted to them. AMH levels were assayed by the Ansh DBS AMH ELISA and compared according to participant characteristics.

MAIN RESULTS AND THE ROLE OF CHANCE

Among 163 potential participants, 123 (75%) were enrolled. Of those enrolled, 112 (91%) were able to complete DBS self-collection and submit mailed samples adequate for measuring AMH. Participants (mean age 31.6 [SD 5.5]) were 85% white, 87% college graduates and 46% reported higher income. Common cancer types were lymphoma and leukemia (34%), breast cancer (30%) and thyroid or skin cancer (8%). The geometric mean (95% confidence interval) AMH level in DBS samples was 0.24 ng/ml (0.16-0.36). In adjusted analysis, AMH levels for survivors of breast cancer (0.02 ng/ml [0.01-0.07]) or leukemia/lymphoma (0.03 ng/ml [0.01-0.08]) were lower than the levels in thyroid or skin cancer survivors (0.12 ng/ml [0.03-0.44]). Pelvic radiation remained associated with lower AMH levels (0.20 ng/ml [0.10-0.40] in unexposed versus 0.02 ng/ml [0.01-0.06] in exposed). Amenorrheic survivors had AMH levels (0.02 ng/ml [0.01-0.06]) that were lower than those of YCS with 7-9 (0.09 ng/ml [0.03-0.32]) or ≥10 (0.17 ng/ml [0.08-0.37]) menstrual periods in the past year.

LIMITATIONS, REASONS FOR CAUTION

The results are generalizable to a population of highly educated, higher income YCS. It is unclear how generalizable the results are to other populations.

WIDER IMPLICATIONS OF THE FINDINGS

Self-collected DBS is a patient-friendly and minimally invasive tool for studying ovarian reserve in geographically diverse populations.

STUDY FUNDING/COMPETING INTERESTS

Research related to the development of this paper was supported by the National Institutes of Health, grants UL1 RR024926 pilot and HD080952-02, and by the American Cancer Society MRSG-08-110-01-CCE. The authors report no competing interests.

The Great Smoky Mountains Study: developmental epidemiology in the southeastern United States

AIMS

To describe the Great Smoky Mountains Study (GSMS).

METHODS

GSMS is a longitudinal study of child psychiatric disorders that began in 1992 to look at need for mental health services in a rural area of the USA. Over 20 years it has expanded its range to include developmental epidemiology more generally, not only the development of psychiatric and substance abuse problems but also their correlates and predictors: family and environmental risk, physical development including puberty, stress and stress-related hormones, trauma, the impact of poverty, genetic markers, and epigenetics. Now that participants are in their 30s the focus has shifted to adult outcomes of childhood psychopathology and risk, and early physical, cognitive, and psychological markers of aging.

RESULTS

This paper describes the results from over 11,000 interviews, examples of the study's contributions to science and policy, and plans for the future.

CONCLUSIONS

Longitudinal studies can provide insights that aid in policy planning.

Links among inflammation, sexual activity and ovulation: Evolutionary trade-offs and clinical implications

Inflammation in healthy sexually active women decreased at midcycle, around ovulation, which may have evolved to promote conception.

Background and objectives: We examined a mechanism that may coordinate trade-offs between reproduction and immune response in healthy women, namely, changes in inflammation across the ovarian cycle.

Methodology: We investigated C-reactive protein (CRP), an inflammation marker, across two consecutive ovarian cycles in 61 Bolivian women. Participants provided saliva samples every other day, and dried blood spots on 5–6 days spread across weeks 2–3 of each cycle. Cycles were characterized as ovulatory/anovulatory based on profiles of reproductive hormones. Participants also reported whether they were sexually partnered with a male or sexually abstinent during the study.

Results: High early-cycle, but not late-cycle, CRP was associated with anovulation. High inflammation at the end of one cycle was not associated with anovulation in the subsequent cycle. Among ovulatory cycles, women with sexual partners had significantly lower CRP at midcycle, and higher CRP at follicular and luteal phases; in contrast, sexually abstinent women had little cycle-related change in CRP. In anovulatory cycles, partnership had no effect on CRP. CRP varied significantly with socioeconomic status (higher in better-off than in poorer women).

Conclusions and implications: These findings suggest that the cycle-specific effect of inflammation on ovarian function may be a flexible, adaptive mechanism for managing trade-offs between reproduction and immunity. Sociosexual behavior may moderate changes in inflammation across the ovarian cycle, suggesting that these shifts represent evolved mechanisms to manage the trade-offs between reproduction and immunity. Clinically, these findings support considering both menstrual cycle phase and sexual activity in evaluations of pre-menopausal women’s CRP concentrations.

A longitudinal study: changes in cortical thickness and surface area during pubertal maturation

Sex hormones have been shown to contribute to the organization and function of the brain during puberty and adolescence. Moreover, it has been suggested that distinct hormone changes in girls versus boys may contribute to the emergence of sex differences in internalizing and externalizing behavior during adolescence. In the current longitudinal study, the influence of within-subject changes in puberty (physical and hormonal) on cortical thickness and surface area was examined across a 2-year span, while controlling for age. Greater increases in Tanner Stage predicted less superior frontal thinning and decreases in precuneus surface area in both sexes. Significant Tanner Stage and sex interactions were also seen, with less right superior temporal thinning in girls but not boys, as well as greater decreases in the right bank of the superior temporal sulcus surface area in boys compared to girls. In addition, within-subject changes in testosterone over the 2-year follow-up period were found to relate to decreases in middle superior frontal surface area in boys, but increases in surface area in girls. Lastly, larger increases in estradiol in girls predicted greater middle temporal lobe thinning. These results show that within-subject physical and hormonal markers of puberty relate to region and sex-specific changes in cortical development across adolescence.

The signs of stress: embodiments of biosocial stress among type 2 diabetic women in New Delhi, India

Biocultural models of health and illness are increasingly used to trace how social pathways shape biological outcomes. Yet, data on the interactions between social and biological aspects of health are lacking in low- and middle-income regions, where two-thirds of all type 2 diabetes cases occur. This study explored health, social roles, and biological correlates among a group of 280 type 2 diabetic and non-diabetic women (n = 184 diabetic) in New Delhi, India, between 2009 and 2011. Using a biocultural framework, we developed and tested a series of hypotheses about the relationships that might exist between diabetes, psychological distress, social role fulfillment, and biological markers measuring blood sugar control, generalized inflammation, and immune stress. Although blood glucose and glycated hemoglobin levels indicated that women's diabetes was generally poorly controlled, they lacked the elevated inflammation, immune stress, and mental ill health that often accompany uncontrolled blood sugar. Qualitative work on explanatory models of diabetes and gendered models of appropriate behavior demonstrated that despite living with poorly controlled diabetes, women maintain participation in culturally valued roles involving the care of others. We suggest that behavioral congruence with these gendered roles may buffer diabetic women's mental health and perhaps even their long-term physical health, while simultaneously posing challenges for their diabetes self-care. To our knowledge, this is the first study to explore the experience of type 2 diabetes in India from an integrated biocultural perspective.

Pharmacokinetic-pharmacodynamic study of subcutaneous injection of depot nandrolone decanoate using dried blood spots sampling coupled with ultrapressure liquid chromatography tandem mass spectrometry assays

CONTEXT

Testosterone (T) and nandrolone (N) esters require deep im injections by medical personnel but these often deposit injectate into sc fat so that more convenient sc self-administration may be feasible.

OBJECTIVE

To investigate the feasibility and pharmacology of sc injection of N decanoate in healthy men using dried blood spot (DBS) for frequent blood sampling without clinic visits.

SETTING AND DESIGN

Healthy male volunteers received 100 mg N decanoate by a single sc injection. Finger-prick capillary blood was spotted onto filter paper before injection daily at home for 21 d and stored at room temperature. Venous whole blood was also spotted onto filter paper before and weekly for 3 wk after injection. DBS were extracted for assay of N and T by liquid chromatography tandem mass spectrometry in a single batch with serum concentrations estimated with adjustment for capillary blood sample volume and hematocrit to define peak (N) or nadir (T) time and concentration from individual daily measurements.

RESULTS

Daily serum N peaked 2.50 ± 0.25 (SEM) ng/mL at a median (range) of 6 (4-13) days causing a reduction in serum T from 3.50 ± 0.57 ng/mL at baseline to a nadir of 0.38 ± 0.13 (SEM) ng/mL (89 ± 3% suppression) at a median (range) of 8 (5-16) days. Simultaneously sampled capillary, venous whole blood, and serum gave almost identical results for serum T and N. Finger-pricks and sc injections were well tolerated.

CONCLUSIONS

This study demonstrates that A) DBS sampling with liquid chromatography mass spectrometry steroid analysis achieves frequent time sampling in the community without requiring clinic visits, venesection, or frozen serum storage, and B) androgen esters in an oil vehicle can be delivered effectively by sc injection, thus avoiding the need for medically supervised deep-im injections.

The role of testosterone and estradiol in brain volume changes across adolescence: a longitudinal structural MRI study

It has been postulated that pubertal hormones may drive some neuroanatomical changes during adolescence, and may do so differently in girls and boys. Here, we use growth curve modeling to directly assess how sex hormones [testosterone (T) and estradiol (E₂)] relate to changes in subcortical brain volumes utilizing a longitudinal design. 126 adolescents (63 girls), ages 10 to 14, were imaged and restudied ∼2 years later. We show, for the first time, that best-fit growth models are distinctly different when using hormones as compared to a physical proxy of pubertal maturation (Tanner Stage) or age, to predict brain development. Like Tanner Stage, T and E₂ predicted white matter and right amygdala growth across adolescence in both sexes, independent of age. Tanner Stage also explained decreases in both gray matter and caudate volumes, whereas E₂ explained only gray matter decreases and T explained only caudate volume decreases. No pubertal measures were related to hippocampus development. Although specificity was seen, sex hormones had strikingly similar relationships with white matter, gray matter, right amygdala, and bilateral caudate volumes, with larger changes in brain volume seen at early pubertal maturation (as indexed by lower hormone levels), followed by less robust, or even reversals in growth, by late puberty. These novel longitudinal findings on the relationship between hormones and brain volume change represent crucial first steps toward understanding which aspects of puberty influence neurodevelopment.

Childhood bullying involvement predicts low-grade systemic inflammation into adulthood

Bullying is a common childhood experience that involves repeated mistreatment to improve or maintain one's status. Victims display long-term social, psychological, and health consequences, whereas bullies display minimal ill effects. The aim of this study is to test how this adverse social experience is biologically embedded to affect short- or long-term levels of C-reactive protein (CRP), a marker of low-grade systemic inflammation. The prospective population-based Great Smoky Mountains Study (n = 1,420), with up to nine waves of data per subject, was used, covering childhood/adolescence (ages 9-16) and young adulthood (ages 19 and 21). Structured interviews were used to assess bullying involvement and relevant covariates at all childhood/adolescent observations. Blood spots were collected at each observation and assayed for CRP levels. During childhood and adolescence, the number of waves at which the child was bullied predicted increasing levels of CRP. Although CRP levels rose for all participants from childhood into adulthood, being bullied predicted greater increases in CRP levels, whereas bullying others predicted lower increases in CRP compared with those uninvolved in bullying. This pattern was robust, controlling for body mass index, substance use, physical and mental health status, and exposures to other childhood psychosocial adversities. A child's role in bullying may serve as either a risk or a protective factor for adult low-grade inflammation, independent of other factors. Inflammation is a physiological response that mediates the effects of both social adversity and dominance on decreases in health.

Comparability of HbA1c and lipids measured with dried blood spot versus venous samples: a systematic review and meta-analysis

Background

Levels of haemoglobin A1_c (HbA1_c) and blood lipids are important determinants of risk in patients with diabetes. Standard analysis methods based upon venous blood samples can be logistically challenging in resource-poor settings where much of the diabetes epidemic is occurring. Dried blood spots (DBS) provide a simple alternative method for sample collection but the comparability of data from analyses based on DBS is not well established.

Methods

We conducted a systematic review and meta-analysis to define the association of findings for HbA1_c and blood lipids for analyses based upon standard methods compared to DBS. The Cochrane, Embase and Medline databases were searched for relevant reports and summary regression lines were estimated.

Results

705 abstracts were found by the initial electronic search with 6 further reports identified by manual review of the full papers. 16 studies provided data for one or more outcomes of interest. There was a close agreement between the results for HbA1_c assays based on venous and DBS samples (DBS = 0.9858venous + 0.3809), except for assays based upon affinity chromatography. Significant adjustment was required for assays of total cholesterol (DBS = 0.6807venous + 1.151) but results for triglycerides (DBS = 0.9557venous + 0.1427) were directly comparable.

Conclusions

For HbA1_c and selected blood lipids, assays based on DBS samples are clearly associated with assays based on standard venous samples. There are, however, significant uncertainties about the nature of these associations and there is a need for standardisation of the sample collection, transportation, storage and analysis methods before the technique can be considered mainstream. This should be a research priority because better elucidation of metabolic risks in resource poor settings, where venous sampling is infeasible, will be key to addressing the global epidemic of cardiovascular diseases.

Pubertal testosterone influences threat-related amygdala-orbitofrontal cortex coupling

Growing evidence indicates that normative pubertal maturation is associated with increased threat reactivity, and this developmental shift has been implicated in the increased rates of adolescent affective disorders. However, the neural mechanisms involved in this pubertal increase in threat reactivity remain unknown. Research in adults indicates that testosterone transiently decreases amygdala-orbitofrontal cortex (OFC) coupling. Consequently, we hypothesized that increased pubertal testosterone disrupts amygdala-OFC coupling, which may contribute to developmental increases in threat reactivity in some adolescents. Hypotheses were tested in a longitudinal study by examining the impact of testosterone on functional connectivity. Findings were consistent with hypotheses and advance our understanding of normative pubertal changes in neural systems instantiating affect/motivation. Finally, potential novel insights into the neurodevelopmental pathways that may contribute to adolescent vulnerability to behavioral and emotional problems are discussed.

Exciting fear in adolescence: does pubertal development alter threat processing?

Adolescent development encompasses an ostensible paradox in threat processing. Risk taking increases dramatically after the onset of puberty, contributing to a 200% increase in mortality. Yet, pubertal maturation is associated with increased reactivity in threat-avoidance systems. In the first part of this paper we propose a heuristic model of adolescent affective development that may help to reconcile aspects of this paradox, which focuses on hypothesized pubertal increases in the capacity to experience (some) fear-evoking experiences as an exciting thrill. In the second part of this paper, we test key features of this model by examining brain activation to threat cues in a longitudinal study that disentangled pubertal and age effects. Pubertal increases in testosterone predicted increased activation to threat cues, not only in regions associated with threat avoidance (i.e., amygdala), but also regions associated with reward pursuit (i.e., nucleus accumbens). These findings are consistent with our hypothesis that puberty is associated with a maturational shift toward more complex processing of threat cues--which may contribute to adolescent tendencies to explore and enjoy some types of risky experiences.

C-reactive protein and substance use disorders in adolescence and early adulthood: a prospective analysis

BACKGROUND

Dysregulated immune function and elevated inflammation markers are seen in adults with chronic diseases, including some psychiatric disorders, but evidence on inflammation in the case of drug abuse is conflicting.

OBJECTIVE

To test the concurrent and predictive relations between C-reactive protein (CRP) and use and abuse of alcohol, nicotine and cannabis in a longitudinal, population sample of adolescents and young adults, at the period of highest increase in drug use.

METHODS

Data from the prospective population-based Great Smoky Mountains Study (N=1420) were used, covering children in the community assessed at ages 9-16, 19, and 21. Structured interviews were used to assess substance abuse symptoms and DSM-IV substance use disorders. Bloodspots were collected at each assessment and assayed for CRP.

RESULTS

CRP levels were higher in the presence of nicotine, alcohol, and cannabis use and nicotine dependence. In prospective analyses, higher CRP levels predicted cannabis use and nicotine dependence, and nicotine use predicted higher CRP levels, once covariates were included in the models. Significant covariates were age, race (American Indian), and obesity.

CONCLUSIONS

The inter-relationship of CRP and substance abuse has implications for the later health risks associated with early drug and alcohol use and abuse.

A rapid, low-cost quantitative diagnostic method for hepatitis C virus infection using capillary zone electrophoresis

Hepatitis C virus (HCV)-RNA amplification is a costly procedure in terms of time and reagents. Consequently, the search for more a cost-effective specific HCV diagnostic method is of great interest. Capillary zone electrophoresis (CZE) methods that detect HCV in serum, plasma, whole blood, and ascites without the need for sample pretreatment are not currently available. Here, a CZE method was developed that detects a larger specific peak in serum and other body fluids of HCV-infected patients than that found in healthy or hepatitis B virus (HBV)-infected individuals. The nature of the HCV peak was investigated using biochemical treatments, including RNase, DNase, and chymotrypsin enzymes. Electroeluted HCV peak was applied to transmission electron microscopy; electron micrographs showed that the HCV peak was attributed to virus-like particles with diameter and morphological properties similar to non-enveloped HCV nucleocapsids. The determination of CZE-HCV and HCV-RNA levels using quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) in 258 subjects revealed that these two tests were highly correlated (r = 0.92, p < 0.0001). One important issue of HCV testing is the storage conditions of serum to obtain reliable results. Serum samples at -20 °C showed the best preservation of the HCV peak up to one year. In conclusion, we detected HCV using CZE in a microliters volume from different body fluids. Besides the stability of samples in maintaining their peak height, the HCV-CZE test is rapid (<15 min) and a well-suited and low-cost technique. Thus, a major improvement in the quantitative diagnosis of HCV infection was established.

Children with both asthma and depression are at risk for heightened inflammation

OBJECTIVE

To test whether children and adolescents with co-occurring asthma and depression are at risk for elevated inflammation-concurrently and at the next assessment.

STUDY DESIGN

Up to 6 yearly assessments per person from the prospective, population-based Great Smoky Mountains Study (N = 1420) were used, covering children in the community aged 10-16 years old. High-sensitivity C-reactive protein (CRP) was assayed from annual bloodspot collections and provided indicators of elevated inflammation at CRP > 1, CRP > 2, and CRP > 3 mg/L. Depression was assessed with the Child and Adolescent Psychiatric Assessment. Asthma was assessed using a form adapted from the Centers for Disease Control and Prevention National Health Interview Survey.

RESULTS

Controlling common covariates of CRP, the co-occurrence of asthma and depression predicted heightened CRP-concurrently and at the next assessment. In turn, elevated CRP was relatively stable from one assessment to the next.

CONCLUSIONS

The co-occurrence of asthma and depression in childhood poses a risk for substantially elevated inflammation concurrently and over time, which could contribute to pathophysiological processes involved in the development of additional chronic diseases and also to asthma--related morbidity and mortality.

Development and validation of assay protocols for use with dried blood spot samples

Dried blood spots (DBS)--drops of capillary whole blood collected from finger stick--represent a minimally invasive alternative to venipuncture that facilitates the collection of blood samples from research participants in naturalistic, field-based research settings. But the number of validated assays for quantifying biomarkers in DBS samples is relatively low in comparison with serum or plasma. The objective of this review is to discuss the advantages and disadvantages of DBS sampling, and to outline the steps involved in developing and validating an immunoassay for application to DBS samples. These steps include deciding on reagents, preparing calibration and quality control material, evaluating elution protocols, optimizing sample quantity, and assessing multiple aspects of assay performance, including intra- and interassay variation, lower limit of detection, accuracy, stability, and agreement between results from matched DBS and plasma samples. The broader goal of this "how-to" approach is to encourage investigators to validate, implement, and disseminate assay protocols for DBS samples in order to advance field-based research on human biology.

Sex-differentiated changes in C-reactive protein from ages 9 to 21: the contributions of BMI and physical/sexual maturation

BACKGROUND

Sex differences in levels of C-reactive protein (CRP) are well established in adulthood, but little is known about when and why they emerge. Here, we tested longitudinal models of CRP levels from ages 9 to 21, when marked physical and behavioral changes could contribute to growing sex disparities in CRP.

METHODS

Data from the community-based prospective-longitudinal Great Smoky Mountains Study (N=1420) were used. Participants were 9-13 years old at intake and were followed through age 21. High-sensitivity C-reactive protein (CRP) was assayed from up to nine bloodspot collections per person. BMI, physical/sexual maturation, substance use, and control variables were assessed during yearly interviews to age 16, and at ages 19 and 21.

RESULTS

Multilevel models revealed that the development of CRP in females was best described by a quadratic trend: after slow increases in CRP until age 15, the rate of increase accelerated thereafter. Changes in CRP in males were best described by a smaller, linear increase. After sex-differentiated associations with BMI, physical/sexual maturation, and substance use variables had been accounted for, increases in CRP after age 15 no longer differed by sex.

CONCLUSION

Physical/sexual maturation and behavioral changes during adolescence could initiate life-long sex disparities in CRP.

Filter paper blood spot enzyme linked immunoassay for adiponectin and application in the evaluation of determinants of child insulin sensitivity

BACKGROUND

Adiponectin is an adipocyte-derived hormone that acts as a marker of insulin sensitivity. Bloodspot sampling by fingerstick onto filter paper may increase the feasibility of large-scale studies of the determinants of insulin sensitivity. We first describe the validation of an enzyme-linked immunoassay (ELISA) for quantifying adiponectin from dried blood spots and then demonstrate its application in a large trial (PROBIT).

METHODS

We quantified adiponectin from 3-mm diameter discs (≈3 µL of blood) punched from dried blood spots obtained from: i) whole blood standards (validation); and ii) PROBIT trial samples (application) in which paediatricians collected blood spots from 13,879 children aged 11.5 years from 31 sites across Belarus. We examined the distribution of bloodspot adiponectin by demographic and anthropometric factors, fasting insulin and glucose.

RESULTS

In the validation study, mean intra-assay coefficients of variation (n=162) were 15%, 13% and 10% for 'low' (6.78 µg/ml), 'medium' (18.18 µg/ml) and 'high' (33.13 µg/ml) internal quality control (IQC) samples, respectively; the respective inter-assay values (n=40) were 23%, 21% and 14%. The correlation coefficient between 50 paired whole bloodspot versus plasma samples, collected simultaneously, was 0.87 (95% CI: 0.78 to 0.93). Recovery of known quantities of adiponectin (between 4.5 to 36 µg/ml) was 100.3-133%. Bloodspot adiponectin was stable for at least 30 months at -80°C. In PROBIT, we successfully quantified fasting adiponectin from dried blood spots in 13,329 of 13,879 (96%) children. Mean adiponectin (standard deviation) concentrations were 17.34 µg/ml (7.54) in boys and 18.41 µg/ml (7.92) in girls and were inversely associated with body mass index, fat mass, triceps and subscapular skin-fold thickness, waist circumference, height and fasting glucose.

CONCLUSIONS

Bloodspot ELISA is suitable for measuring adiponectin in very small volumes of blood collected on filter paper and can be applied to large-scale studies.

High quality methylome-wide investigations through next-generation sequencing of DNA from a single archived dry blood spot

The potential importance of DNA methylation in the etiology of complex diseases has led to interest in the development of methylome-wide association studies (MWAS) aimed at interrogating all methylation sites in the human genome. When using blood as biomaterial for a MWAS the DNA is typically extracted directly from fresh or frozen whole blood that was collected via venous puncture. However, DNA extracted from dry blood spots may also be an alternative starting material. In the present study, we apply a methyl-CpG binding domain (MBD) protein enrichment-based technique in combination with next generation sequencing (MBD-seq) to assess the methylation status of the ~27 million CpGs in the human autosomal reference genome. We investigate eight methylomes using DNA from blood spots. This data are compared with 1,500 methylomes previously assayed with the same MBD-seq approach using DNA from whole blood. When investigating the sequence quality and the enrichment profile across biological features, we find that DNA extracted from blood spots gives comparable results with DNA extracted from whole blood. Only if the amount of starting material is ≤ 0.5µg DNA we observe a slight decrease in the assay performance. In conclusion, we show that high quality methylome-wide investigations using MBD-seq can be conducted in DNA extracted from archived dry blood spots without sacrificing quality and without bias in enrichment profile as long as the amount of starting material is sufficient. In general, the amount of DNA extracted from a single blood spot is sufficient for methylome-wide investigations with the MBD-seq approach.

Generalized anxiety and C-reactive protein levels: a prospective, longitudinal analysis

BACKGROUND

Generalized anxiety disorder (GAD) is highly co-morbid with depression. Depression is associated with elevated levels of the inflammation marker C-reactive protein (CRP), cross-sectionally and over time. To date, no studies have looked at the association between CRP and GAD.

METHOD

A total of nine waves of data from the prospective population-based Great Smoky Mountains Study (n=1420) were used, covering children in the community aged 9-16, 19 and 21 years old. Structured interviews were used at each assessment to assess GAD symptoms, diagnosis and cumulative episodes. Blood spots were collected and assayed for high-sensitivity CRP levels.

RESULTS

GAD was associated with increased levels of CRP in bivariate cross-sectional analyses. These bivariate associations, however, were attenuated after accounting for demographic, substance-use and health-related covariates. In longitudinal models, there was little evidence that CRP predicted later GAD. Associations from GAD to later CRP were attenuated in models adjusted for health-related coavariates and there was evidence that the GAD-CRP association was mediated by body mass index (BMI) and medication use.

CONCLUSIONS

Similar to depression, GAD was associated with elevated levels of CRP, but the effect of GAD on CRP levels was explained by the effect of GAD on health-related behaviors such as BMI and medication use. This study suggests differences in the association between inflammation and depression and GAD.

Filter paper blood spot enzyme linked immunoassay for insulin and application in the evaluation of determinants of child insulin resistance

Background

In large-scale epidemiology, bloodspot sampling by fingerstick onto filter paper has many advantages, including ease and low costs of collection, processing and transport. We describe the development of an enzyme-linked immunoassay (ELISA) for quantifying insulin from dried blood spots and demonstrate its application in a large trial.

Methods

We adapted an existing commercial kit (Mercodia Human Insulin ELISA, 10-1113-01) to quantify insulin from two 3-mm diameter discs (≈6 µL of blood) punched from whole blood standards and from trial samples. Paediatricians collected dried blood spots in a follow-up of 13,879 fasted children aged 11.5 years (interquartile range 11.3–11.8 years) from 31 trial sites across Belarus. We quantified bloodspot insulin levels and examined their distribution by demography and anthropometry.

Results

Mean intra-assay (n = 157) coefficients of variation were 15% and 6% for ‘low’ (6.7 mU/L) and ‘high’ (23.1 mU/L) values, respectively; the respective inter-assay values (n = 33) were 23% and 11%. The intraclass correlation coefficient between 50 paired whole bloodspot versus serum samples, collected simultaneously, was 0.90 (95% confidence interval 0.85 to 0.95). Bloodspot insulin was stable for at least 31 months at −80°C, for one week at +30°C and following four freeze-thaw cycles. Paediatricians collected a median of 8 blood spots from 13,487 (97%) children. The geometric mean insulin (log standard deviation) concentrations amongst 12,812 children were 3.0 mU/L (1.1) in boys and 4.0 mU/L (1.0) in girls and were positively associated with pubertal stage, measures of central and peripheral adiposity, height and fasting glucose.

Conclusions

Our simple and convenient bloodspot assay is suitable for the measurement of insulin in very small volumes of blood collected on filter paper cards and can be applied to large-scale epidemiology studies of the early-life determinants of circulating insulin.

A highly sensitive immunoassay for interleukin-6 in dried blood spots

OBJECTIVE

Interleukin-6 (IL-6) is a pro-inflammatory cytokine that is associated with the production of C-reactive protein, the acute phase response, and chronic low-grade inflammation. In this report, we describe and validate a highly sensitive enzyme-linked immunosorbent assay (ELISA) for quantifying IL-6 at low concentrations in samples of capillary whole blood collected from a simple finger stick and dried on filter paper (dried blood spots, DBS).

METHODS

A commercially available ELISA for IL-6 was modified to develop a protocol for the quantification of IL-6 in DBS samples. Procedures for sample elution and incubation were optimized for precision, reliability, accuracy, and lower limit of detection using small volumes of DBS. A set of 46 matched serum/DBS samples were used to evaluate agreement between serum and DBS results.

RESULTS

The protocol demonstrated acceptable levels of precision, reliability, accuracy, and agreement with serum-based results. The lower limit of detection was sufficiently low to measure levels of IL-6 associated with both chronic, low-grade inflammation, and acute increases in inflammatory activity.

CONCLUSIONS

This protocol adds to the growing panel of analytes validated for quantification in DBS samples and should facilitate future research on the causes and consequences of inflammation in diverse non-clinical settings.

Quantification of anti-Müllerian hormone (AMH) in dried blood spots: validation of a minimally invasive method for assessing ovarian reserve

BACKGROUND

Biological markers of ovarian reserve have the potential to advance research on fecundability, infertility and reproductive aging. Anti-Müllerian hormone (AMH) has emerged as a clinically useful measure of ovarian reserve, but the requirement for venous blood is an obstacle to application in non-clinical settings. This paper validates a new method for quantifying AMH in dried blood spot (DBS) samples--drops of whole blood collected on filter paper following a simple finger stick.

METHODS

Matched serum and DBS samples were obtained from n=101 women of reproductive age, and AMH values were compared using regression analyses and scatter plots. The precision, reliability, linearity, recovery and lower detection limit of the DBS assay were evaluated, as well as the stability of AMH in DBS across a range of storage conditions.

RESULTS

There was a strong agreement between AMH concentrations measured in DBS and serum samples across the entire assay range. Analysis of within-assay (percent coefficient of variation, 4.7-6.5%) and between-assay (3.5-7.2%) variability indicated a high level of assay precision and reliability, respectively. The minimum detectable dose of AMH was 0.065 ng/ml. Concentrations of AMH remained stable in DBS samples stored for 2 weeks at room temperature, and for 4 weeks when refrigerated.

CONCLUSIONS

The DBS assay performs at a level that is comparable to serum-based methods, with the advantage of lower burdens and costs associated with blood collection that may be advantageous for research in clinical as well as non-clinical settings on the causes and consequences of variation in ovarian reserve.

Sex matters during adolescence: testosterone-related cortical thickness maturation differs between boys and girls

Age-related changes in cortical thickness have been observed during adolescence, including thinning in frontal and parietal cortices, and thickening in the lateral temporal lobes. Studies have shown sex differences in hormone-related brain maturation when boys and girls are age-matched, however, because girls mature 1–2 years earlier than boys, these sex differences could be confounded by pubertal maturation. To address puberty effects directly, this study assessed sex differences in testosterone-related cortical maturation by studying 85 boys and girls in a narrow age range and matched on sexual maturity. We expected that testosterone-by-sex interactions on cortical thickness would be observed in brain regions known from the animal literature to be high in androgen receptors. We found sex differences in associations between circulating testosterone and thickness in left inferior parietal lobule, middle temporal gyrus, calcarine sulcus, and right lingual gyrus, all regions known to be high in androgen receptors. Visual areas increased with testosterone in boys, but decreased in girls. All other regions were more impacted by testosterone levels in girls than boys. The regional pattern of sex-by-testosterone interactions may have implications for understanding sex differences in behavior and adolescent-onset neuropsychiatric disorders.

Cumulative depression episodes predict later C-reactive protein levels: a prospective analysis

BACKGROUND

Depression is associated with elevated levels of the inflammation marker C-reactive protein (CRP); yet, the direction of this association remains unclear. This study tested bi-directional longitudinal associations between CRP and depression in a sample of adolescents and young adults. The study compared the effect of current depression with the effect of cumulative episodes of depression over time.

METHODS

Nine waves of data from the prospective population-based Great Smoky Mountains Study (n = 1420) were used, covering children in the community aged 9 to 16, 19, and 21 years old. Structured interviews were used to assess depressive symptoms, depression diagnosis, and cumulative depressive episodes. Bloodspots were collected at each observation and assayed for CRP levels.

RESULTS

CRP levels were not associated with later depression status. In contrast, all depression-related variables displayed evidence of association with later CRP levels. The associations with depressive symptoms and diagnostic status were attenuated after controlling for covariates, particularly body mass index, smoking, and medication use. The effect of cumulative depressive episodes, however, continued to be significant after accounting for a range of covariates. Body mass index, smoking behavior, and recent infections may mediate a portion of the effect of cumulative episodes on later CRP, but cumulative depressive episodes continued to predict CRP levels independently.

CONCLUSIONS

The occurrence of multiple depressive episodes exerted the greatest effect on later CRP levels. This suggests that risk for the diseases of middle and old age--cardiovascular and metabolic disease--may begin in childhood and depend, in part, on long-term emotional functioning.

Changing family routines at kindergarten entry predict biomarkers of parental stress

This study tested associations among parenting stress prior to a child’s kindergarten entry, the sustainability of family routines, and biomarkers of stress among parents following the kindergarten transition. Parents (N = 51) with higher prekindergarten scores on the Parenting Stress Index Short Form reported lower Family Routines Inventory scores following school entry relative to their baseline. Declining family routines, in turn, were associated following kindergarten entry with greater 5-day mean and variance in evening cortisol, and higher C-reactive protein, an inflammatory mediator. However, only the cortisol findings remained significant controlling for baseline physiology. These findings support a family systems, social-ecological approach to life course development, wherein even mild challenges posed by children’s normative transitions may reveal differences in parents’ biobehavioral functioning.

Puberty influences medial temporal lobe and cortical gray matter maturation differently in boys than girls matched for sexual maturity

Sex differences in age- and puberty-related maturation of human brain structure have been observed in typically developing age-matched boys and girls. Because girls mature 1-2 years earlier than boys, the present study aimed at assessing sex differences in brain structure by studying 80 adolescent boys and girls matched on sexual maturity, rather than age. We evaluated pubertal influences on medial temporal lobe (MTL), thalamic, caudate, and cortical gray matter volumes utilizing structural magnetic resonance imaging and 2 measures of pubertal status: physical sexual maturity and circulating testosterone. As predicted, significant interactions between sex and the effect of puberty were observed in regions with high sex steroid hormone receptor densities; sex differences in the right hippocampus, bilateral amygdala, and cortical gray matter were greater in more sexually mature adolescents. Within sex, we found larger volumes in MTL structures in more sexually mature boys, whereas smaller volumes were observed in more sexually mature girls. Our results demonstrate puberty-related maturation of the hippocampus, amygdala, and cortical gray matter that is not confounded by age, and is different for girls and boys, which may contribute to differences in social and cognitive development during adolescence, and lasting sexual dimorphisms in the adult brain.

Non-invasive methods for estradiol recovery from infant fecal samples

While the activation of the infant hypothalamic-pituitary-gonadal axis and the existence of a postnatal gonadotropin surge were first documented in the early 1970s, study of the longitudinal development of gonadal hormones in infancy, and the potential physiological and behavioral correlates of this development, have been hampered by reliance on infrequent serum sampling. The present study reports the validation of a non-invasive method for repeated assessment of steroid hormones in infant fecal samples. Fecal samples were collected in and excised from cotton diaper liners and extracted using methanol. Extracts were analyzed for estradiol using a diluted assay modification. Method validity was supported by a steroid recovery rate of at least 80%, a sensitivity of 0.35 pg/ml, and inter- and intra-assay coefficients of variations of less than 10 and 20%, respectively. Variation in estradiol concentration was assessed across (1) sample type (scraped vs. cut from diaper liner), (2) time of day (morning vs. afternoon/evening samples), (3) time interval between samples, and (4) time-to-assay (1 day vs. 489 days after collection). Of these characteristics, only the time interval between samples within an individual was significantly associated with estradiol concentration. This is the first report of human infant fecal estradiol levels. The results support fecal recovery as a novel and powerful non-invasive tool for longitudinal studies of human infants, expanding research opportunities for investigating development of sex-specific behaviors in infancy, and the potential effects of endocrine disruptors on development.

Sex differences in the association between cortisol concentrations and laboratory pain responses in healthy children

BACKGROUND

Research in adult populations has highlighted sex differences in cortisol concentrations and laboratory pain responses, with men exhibiting higher cortisol concentrations and reduced pain responses compared with women. Yet, less is known about the relationship of cortisol concentrations to pain in children.

OBJECTIVE

This study examined associations between sex, cortisol, and pain responses to laboratory pain tasks in children.

METHODS

Salivary cortisol samples from subjects aged 8 to 18 years were obtained at baseline after entering the laboratory (SCb), after the completion of all pain tasks (SC1), and at the end of the session (SC2), 20 minutes later. Blood cortisol samples were also taken after completion of the pain tasks (BC1) and at the end of the session (BC2), 20 minutes later. Subjects completed 3 counterbalanced laboratory pain tasks: pressure, heat, and cold pressor tasks. Pain measures included pain tolerance, and self-reported pain intensity and unpleasantness for all 3 tasks.

RESULTS

The study included 235 healthy children and adolescents (119 boys, 116 girls; mean age, 12.7 years; range, 8-18 years; 109 [46.4%] were in early puberty; 94 [40.0%] white). Salivary and blood cortisol levels were highly correlated with each other. Salivary cortisol levels for the total sample and for boys and girls declined significantly from SCb to SC1 (P < 0.01), although there were no significant changes from SC1 to SC2. No significant sex differences in salivary or blood cortisol levels were evident at any assessment point. Separate examination of the cortisol-laboratory pain response relationships by sex (controlling for age and time of day) suggested different sex-specific patterns. Higher cortisol levels were associated with lower pain reactivity (ie, increased pressure tolerance) among boys compared with girls at SC1, SC2, and BC1 (SC1: r = 0.338, P = 0.003; SC2: r = 0.271, P = 0.020; and BC1: r = 0.261, P = 0.026). However, higher cortisol levels were related to higher pain response (ie, increased cold intensity [BC2: r = 0.229, P = 0.048] and unpleasantness [BC1: r = 0.237, P = 0.041]) in girls compared with boys.

CONCLUSIONS

These findings suggest important sex differences in cortisol-pain relationships in children and adolescents. Cortisol levels were positively associated with increased pain tolerance in boys and increased pain sensitivity in girls.

The role of puberty in the developing adolescent brain

Adolescence refers to the period of physical and psychological development between childhood and adulthood. The beginning of adolescence is loosely anchored to the onset of puberty, which brings dramatic alterations in hormone levels and a number of consequent physical changes. Puberty onset is also associated with profound changes in drives, motivations, psychology, and social life; these changes continue throughout adolescence. There is an increasing number of neuroimaging studies looking at the development of the brain, both structurally and functionally, during adolescence. Almost all of these studies have defined development by chronological age, which shows a strong—but not unitary—correlation with pubertal stage. Very few neuroimaging studies have associated brain development with pubertal stage, and yet there is tentative evidence to suggest that puberty might play an important role in some aspects of brain and cognitive development. In this paper we describe this research, and we suggest that, in the future, developmental neuroimaging studies of adolescence should consider the role of puberty. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.