Publications by authors named "David Zava"

Background: The International Cohort on Lifestyle Determinants of Health (INCLD Health) is an ongoing, prospective cohort study assessing the health behaviours and lifestyles of higher education students, including their use of specialty diets and complementary and integrative health (CIH) practices.

Purpose: This cross-sectional analysis of the INCLD Health cohort aims to (1) evaluate the associations between perceived stress, sleep disturbance, and meditative practices with diurnal salivary free cortisol and (2) evaluate the associations of meditative practices as well as mind-body practices with perceived stress and sleep disturbance.

Methods: Serial multivariable linear regression models, adjusting for sociodemographic and lifestyle behaviours, were used to assess associations of (1) perceived stress, sleep disturbance, and meditative practices with salivary cortisol, and (2) meditative practices as well as mind-body practices with perceived stress and sleep disturbance.

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Limited data exist on the reproductive hormone dynamics that govern the transition from menarche to the establishment of the mature ovulatory cycles of a fertile young woman. It is also unclear how environmental and lifestyle factors could modulate this transition in contemporary girls. Here, we introduce A Girl's First Period Study, an ambitious longitudinal study aimed at charting the early post-menarchal course of a cohort of healthy girls in the Triangle region of North Carolina.

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Existing theories suggest that moderate arousal improves selective attention, as would be expected in the context of competitive sports or sensation-seeking activities. Here we investigated how riding a motorcycle, an attention-demanding physical activity, affects sensory processing. To do so, we implemented the passive auditory oddball paradigm and measured the EEG response of participants as they rode a motorcycle, drove a car, and sat at rest.

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Coronavirus disease 2019 antibody testing often relies on venous blood collection, which is labor-intensive, inconvenient and expensive compared with finger-stick capillary dried blood spot (DBS) collection. The purpose of our work was to determine if two commercially available anti-severe acute respiratory syndrome coronavirus 2 enzyme-linked immunosorbent assays for IgG antibodies against spike S1 subunit and nucleocapsid proteins could be validated for use with DBS. Kit supplied reagents were used to extract DBS, and in-house DBS calibrators were included on every run.

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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.

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Aldosterone and cortisone are released in response to physical and psychological stress. However, aldosterone and cortisone responses in children engaged in physical competition have not been described. We examined salivary aldosterone and salivary cortisone responses among Hong Kongese boys, aged 8-11 years, during (1) a soccer match against unknown competitors ( = 84, high psychological stress condition) and (2) an intrasquad soccer scrimmage against teammates ( = 81, low psychological stress condition).

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Sex hormone metabolism is altered during mammary gland tumorigenesis, and different metabolites may have different effects on mammary epithelial cells. This study aimed to evaluate associations between urinary sexual metabolite levels and breast cancer risk among premenopausal women of Mainland China. The molecular metabolism of the cancer-related metabolites was also explored based on the clinical data.

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The capacity to infer others' mental states (known as 'mind reading' and 'cognitive empathy') is essential for social interactions across species, and its impairment characterizes psychopathological conditions such as autism spectrum disorder and schizophrenia. Previous studies reported that testosterone administration impaired cognitive empathy in healthy humans, and that a putative biomarker of prenatal testosterone exposure (finger digit ratios) moderated the effect. However, empirical support for the relationship has relied on small sample studies with mixed evidence.

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Introduction: Clinical studies conducted in the early to mid-twentieth century, and recent self-reports by some maternal placentophagy practitioners, suggest that human maternal placentophagy improves breast milk quality and quantity, although little research has evaluated this claim. Some placentophagy providers and advocates suggest that increased prolactin levels after placenta ingestion could account for the purported lactation benefits. The current study was conducted to evaluate these claims by comparing plasma prolactin levels of women consuming steamed, dehydrated, and encapsulated placenta with those of women consuming a placebo.

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Context: During puberty, LH pulse frequency increases during sleep; in women, LH pulse frequency slows during sleep in the early/middle follicular phase (FP) of the menstrual cycle. The origin and significance of this developmental transition are unknown.

Objective: To determine the relationship between progesterone (P4) exposure, sleep-related slowing of LH pulses in the FP, and the intercycle FSH rise, which promotes folliculogenesis, in early postmenarchal girls.

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Many FA who flew prior to the ban on smoking in commercial aircraft exhibit an unusual pattern of long-term pulmonary dysfunction. This randomized controlled study tested the hypothesis that digitally delivered meditative movement (MM) training improves chronic obstructive pulmonary disease (COPD)-related symptoms in flight attendants (FA) who were exposed to second-hand cigarette smoke (SHCS) while flying. Phase I of this two-phase clinical trial was a single-arm non-randomized pilot study that developed and tested methods for MM intervention; we now report on Phase II, a randomized controlled trial comparing MM to a control group of similar FA receiving health education (HE) videos.

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Objectives: Little is known about salivary steroid hormone responses to dyadic competition among prepubescent boys. The current study explored pre-match and post-match testosterone, dehydroepiandrosterone (DHEA), androstenedione, and cortisol among 22 ethnically Chinese, Hong Kongese table tennis athletes, aged 8-11 years, during dyadic competition against peers. These data provide novel comparative insight into boys' hormone responses when participating in similar forms of competition to that of adults.

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Context: Menstrual irregularity after menarche has been attributed to immature estrogen positive feedback activity (E+FB) but data are conflicting.

Objective: To determine the hypothalamic-pituitary-ovarian contributions to menstrual irregularity in adolescents.

Methods: Twenty-three healthy girls [aged 12.

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A large body of research links testosterone and cortisol to male-male competition. Yet, little work has explored acute steroid hormone responses to coalitional, physical competition during middle childhood. Here, we investigate testosterone, dehydroepiandrosterone (DHEA), androstenedione, and cortisol release among ethnically Chinese boys in Hong Kong (N = 102), aged 8-11 years, during a soccer match (n = 84) and an intrasquad soccer scrimmage (n = 81), with 63 participants competing in both treatments.

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Testicular germ cell tumor (TGCT) incidence has increased over the last 40 years in the United States. In contrast to TGCT among infants, it is hypothesized that TGCT in adolescents and young men is the result of sex steroid hormone imbalance during early fetal development. However, little is known about the neonatal period when abrupt hormonal changes occur, and direct supporting evidence is scarce due to the difficulties in obtaining prediagnostic specimens.

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Iodine is crucial for thyroid hormone production. However, recent epidemiologic studies have shown that breast cancer patients have an elevated risk of developing thyroid cancer and vice versa. A notable finding in this study is that iodine stimulated the transcriptional activity of estrogen receptor-α (ER-α) in breast cancer cells.

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Background: Recent studies show that human placenta, processed and encapsulated for postpartum consumption, contains a host of trace minerals and hormones that could conceivably affect maternal physiology. Our objective was to investigate whether salivary hormone concentrations of women ingesting their own encapsulated placenta during the early postpartum differed from those of women consuming a placebo.

Methods: Randomly assigned participants (N=27) were given a supplement containing either their dehydrated and homogenized placenta (n=12), or placebo (n=15).

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Background: Human maternal placentophagy is gaining popularity among a growing number of women who believe it provides maternal benefits, including prevention of postpartum blues/depression, improved maternal bonding, and reduced fatigue.

Methods: We conducted a randomized, double-blind, placebo-controlled pilot study (N=27) in which participants consumed either their processed, encapsulated placenta (n=12), or similarly prepared placebo (n=15). Maternal mood, bonding, and fatigue were assessed via validated scales across four time points during late pregnancy and early postpartum.

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BACKGROUND The aim of this study was to evaluate changes in sex hormone metabolism in patients with threatened miscarriage. MATERIAL AND METHODS We recruited 73 women in early pregnancy (6-8 weeks of gestation) and divided them into the following 2 groups based on whether they had vaginal bleeding: group A (n=34), the threatened abortion group; and group B (n=39), the normal pregnancy group. Human chorionic gonadotrophin (hCG), estradiol (E2), progesterone (P4), and testosterone (T) serum levels were tested and sex hormone metabolites in the urine were detected using gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS).

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In nonhumans, the sex steroid testosterone regulates reproductive behaviors such as fighting between males and mating. In humans, correlational studies have linked testosterone with aggression and disorders associated with poor impulse control, but the neuropsychological processes at work are poorly understood. Building on a dual-process framework, we propose a mechanism underlying testosterone's behavioral effects in humans: reduction in cognitive reflection.

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This single-arm non-randomized pilot study explores an intervention to improve the health of flight attendants (FA) exposed to second-hand cigarette smoke prior to the smoking ban on commercial airlines. This group exhibits an unusual pattern of long-term pulmonary dysfunction. We report on Phase I of a two-phase clinical trial; the second Phase will be a randomized controlled trial testing digital delivery of the intervention.

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Introduction: Advocates of human maternal placentophagy report that encapsulated placenta is an excellent source of dietary iron. Our study compared the effect of ingested encapsulated placenta on maternal postpartum iron status versus that of a beef placebo.

Methods: A randomized, double-blind, placebo-controlled pilot study (N = 23) was conducted among healthy human research participants experiencing a normal pregnancy.

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Human maternal placentophagy is a rare but growing practice in several industrialized countries among postpartum mothers seeking a variety of purported health benefits attributed to the practice. These postpartum mothers typically consume their placenta as a processed, encapsulated supplement. To determine whether free (unconjugated) steroid hormones and melatonin in placenta can survive the encapsulation process (namely steaming and dehydration), we analyzed 28 placenta samples processed for encapsulation using liquid chromatography tandem-mass spectrometry (LC-MS/MS) to evaluate the concentration of 17 hormones.

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