David Zava

• PhD
• Researcher at ZRT Laboratory

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 may modulate this transition in contemporary girls. Here we introduce A Girl's First Period Study, an ambitious long...

Aim: 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...

Objective Among adults, aldosterone and cortisone increases are reported in response to physically taxing forms of competition, enabling individuals to rapidly adapt to variable sociocompetitive contexts. Yet, aldosterone and cortisone responses in juvenile children engaged in less strenuous forms of competition have not been investigated. Here, we...

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 unkno...

Knight, McShane, et al. (2020) report three experiments on testosterone’s effect on the Cognitive Reflection Test (CRT). The experiments were designed and executed independently of each other and of our previous work (Nave, Nadler, Zava & Camerer, 2017). We thank Knight, McShane, et al. for conducting these experiments and summarizing their results...

The capacity to infer the mental states of others (known as cognitive empathy) is essential for social interactions, and a well-known theory proposes that it is negatively affected by intrauterine testosterone exposure. Furthermore, previous studies reported that testosterone administration impaired cognitive empathy in healthy adults, and that a b...

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...

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...

Context During puberty, LH pulse frequency increases during sleep; in women, LH pulse frequency slows during sleep in the early/mid-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...

The capacity to infer the mental states of others (known as cognitive empathy) is essential for social interactions, and a well-known theory proposes that it is negatively affected by intrauterine testosterone exposure. Furthermore, previous studies reported that testosterone administration impaired cognitive empathy in healthy adults, and that a b...

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...

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 23 healthy girls (aged 12.8-17.6 years, 0.4-3.5 years post-menarche, BMI [body...

Objectives Little psychoneuroendocrine research has focused on steroid hormone responses to non-physical competition in middle childhood. This study sought to observe testosterone, estradiol, dehydroepiandrosterone (DHEA), androstenedione, and cortisol responses in children during a mixed-sex, team, academic competition. Methods Salivary steroid ho...

In modern human cultures where social hierarchies are ubiquitous, people typically signal their hierarchical position through consumption of positional goods—goods that convey one’s social position, such as luxury products. Building on animal research and early correlational human studies linking the sex steroid hormone testosterone with hierarchic...

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 K...

Background: 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...

Esports, or competitive video gaming, has rapidly increased in online play and viewing. The popularity of esports such as League of Legends may derive in part because it features skills-based coalitional competition. Whereas a sizable literature focuses on adult human hormones and competition, little research has addressed the hormone responses of...

The sex steroid testosterone regulates reproductive behaviors such as intra-male fighting and mating in non-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...

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 po...

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 participant...

Background The aim of this study was to evaluate changes in sex hormone metabolism in patients with threatened miscarriage. Material/Method 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 gro...

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. Iodine stimulat...

Testicular germ cell tumors (TGCT) are the most commonly occurring cancers in adolescent and young adult males in the U.S. Steroid sex hormones play a central role in the development of the testis. As proposed by the testicular dysgenesis syndrome hypothesis, the origins of TGCT are likely to be in utero or early in life, and to be a manifestation...

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 wi...

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 conduc...

Tobacco smoking is a major risk factor for a number of chronic diseases, including a variety of cancers, lung disease and damage to the cardiovascular system. The World Health Organization recently calculated that there were 6 million smoking-attributable deaths per year and that this number is due to rise to about eight million per year by the end...

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 hormon...

A study protocol is presented for the investigation of meditative movement (MM) as a treatment for pulmonary dysfunction in flight attendants (FA) who were exposed to second-hand cigarette smoke while flying before the smoking ban. The study will have three parts, some of which will run concurrently. The first is a data gathering and screening phas...

We examined potential changes in salivary DHEA, androstenedione, cortisol, testosterone, and cortisol/DHEA ratio in boys in response to soccer practice and soccer match competition. To our knowledge, this study is the first to explore the impacts of athletic competition on salivary steroid hormone change in juvenile boy soccer players. Boys from fi...

There have been few studies of whether vitamin D insufficiency is linked with depression in healthy young women despite women׳s high rates of both problems. Female undergraduates (n=185) living in the Pacific Northwest during fall, winter, and spring academic terms completed the Center for Epidemiologic Studies Depression (CES-D) scale weekly for 4...

As first responders who are frequently exposed to job-related trauma, police officers are at an elevated risk of adverse mental and physical health outcomes. Evidence-based approaches to stress reduction are sorely needed to address the complex variety of problems that police officers face. In this pilot study we examined the feasibility and prelim...

Though fibromyalgia is not traditionally considered an inflammatory disorder, evidence for elevated inflammatory processes has been noted in this disorder in multiple studies. Support for inflammatory markers in fibromyalgia has been somewhat equivocal to date, potentially due to inattention to salient patient characteristics that may affect inflam...

Abstract not available.

Abstract not available.

OBJECTIVE: This study aims to investigate the distribution of progesterone in venous whole blood, venous serum, fingertip capillary blood, and saliva after its topical application in both cream and gel formulations. METHODS: Ten postmenopausal women were randomized to receive 80 mg of progesterone cream or gel applied daily for 14 days, crossing ov...

Background: Menopause annually affects 25 million women worldwide, and WHO estimates 1.2 billion women will be postmenopausal by 2030. Symptoms of vasomotor changes resulting in hot flashes and night sweats, dysphonic mood, and sleep disturbances affect quality of life in this aging population. Age- related conditions including cardiovascular disea...

Iodine deficiency is a world-wide health problem. A simple, convenient, and inexpensive method to monitor urine iodine levels would have enormous benefit in determining an individual's recent iodine intake or in identifying populations at risk for iodine deficiency or excess. Current methods used to monitor iodine levels require collection of a lar...

ABSTRACT: Japanese iodine intake from edible seaweeds is amongst the highest in the world. Predicting the type and amount of seaweed the Japanese consume is difficult due to day-to-day meal variation and dietary differences between generations and regions. In addition, iodine content varies considerably between seaweed species, with cooking and/or...

Background Correlation between circulating sex steroid levels and breast cancer has been controversial, with measurement of free, or bioavailable hormone rarely available. Salivary hormone levels represent the bioavailable fraction. To further elucidate the role of endogenous hormones in breast cancer, we aimed to assess correlation between salivar...

Although research suggests that socio-sexual behavior changes in conjunction with the menstrual cycle, several potential factors are rarely taken into consideration. We investigated the role of changing hormone concentrations on self-reported physical discomfort, sleep, exercise and socio-sexual interest in young, healthy women. Salivary hormones (...

High levels of insulin and lipids following a meal are recognized risk factors for atherosclerosis. Monitoring such risk factors in the general population is hampered by the inconvenience of venipuncture blood collection, particularly for both premeal and postmeal analyses. This study examined insulin and triglyceride levels in dried blood spots (D...

This article is an adaptation of an abstract/poster presentaton made at the 13th International Congress on Steroidal Hormones and Hormones and Cancer, Quebec City, Canada (September 2008), concerning the topic of breast feeding as a contraindication to testosterone therapy. The purpose of the presentation and this article is to provide a summary of...

Now emerging as an important risk factor for type 1 diabetes, vitamin D deficiency is also associated with obesity, metabolic syndrome, and type 2 diabetes and has been identified as a potential cardiometabolic risk factor. A simple, accurate screening test for 25-hydroxy vitamin D [25(OH)D] deficiency is needed. We developed a liquid chromatograph...

This article is an adaptation of an abstract/poster presentation made at the 13th International Congress on Steroidal Hormones and Hormones & Cancer, Quebec City, Canada (September 2008), concerning the topic of breast feeding as a contraindication to testosterone therapy. The purpose of the presentation and this article is to provide a summary of...

There is a lack of evidence in the literature supporting vaginal application of a combination hormone-containing cream for local and systemic symptom relief. This pilot study examined the extent of absorption of a single cream containing estriol, estradiol, progesterone, DHEA, and testosterone. A combination cream was administered to 12 postmenopau...

Cardiovascular and metabolic risk factors are gaining attention as potential indicators for intervention in the prevention and treatment of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Blood spot technology offers an efficient, convenient method to measure these risk factors in an at-risk population. Simple and convenient metho...

To compare LH, FSH, P, and E(2) levels obtained from blood spot vs. plasma (single-visit study) and to determine whether blood spots can document circulating hormone levels during ovulatory cycles (menstrual-cycle study). Cross-sectional study. Academic center. Women 18-35 years of age with regular menstrual cycles and no recent use of hormonal con...

Postmenopausal women have an increased risk of cardiovascular disease, and heart disease is the leading cause of death in postmenopausal American women. Conventional hormone replacement therapy has been shown to result in an increase in thrombotic events in large prospective clinical trials including HERS I, and the recently halted Women’s Health I...

Abstract not available.

This study investigated in 40 young university women the possible relationships between levels of testosterone and specific measures of overall self-confidence and self-confidence in approaching mathematics. Correlations of -.43 and -.49 with each measure of self-confidence, respectively, and level of testosterone were found in the portion of the s...

This study investigated in 40 young university women the possible relationships between levels of testosterone and specific measures of overall self-confidence and self-confidence in approaching mathematics. Correlations of -.43 and -.49 with each measure of self-confidence, respectively, and level of testosterone were found in the portion of the s...

In this study we report on the content and bioactivity of plant (phyto) estrogens and progestins in various foods, herbs, and spices, before and after human consumption. Over 150 herbs traditionally used by herbalists for treating a variety of health problems were extracted and tested for their relative capacity to compete with estradiol and proges...

We investigated the estrogenic activity of various environmental pollutants (xenobiotics), in particular the xenoestrogen o,p-DDT, and compared their effects with those of endogenous estrogens, phytoestrogens, and mycoestrogens on estrogen receptor binding capacity, induction of estrogen end products, and activation of cell proliferation in estroge...

We assessed distributions of breast cancer prognostic biomarkers by race/ethnicity and socioeconomic position among paraffin-embedded tumor biopsy specimens from 135 US women (48 white women, 44 black women, 43 Asian women) diagnosed with breast cancer between 1966 and 1990. No racial/ethnic or socioeconomic differences in distributions were observ...

Experimental and epidemiologic studies support the view that soyfoods prevent cancer as well as diseases and symptoms associated with estrogen deficiency. Recent research suggests that the isoflavonoid genistein, a phytoestrogen found in abundance in soyfoods, may be one of the principal molecular components responsible for these health benefits. I...

Compounds that either inhibit or induce an estrogen response in vivo are important as potential drugs and biochemical tools. Non-steroidal stilbene analogs such as tamoxifen are known to function as both estrogen agonists and antagonists depending upon the analog structure. This family of compounds is amenable to parallel-manifold synthesis because...

The prognostic significance of Cathepsin D and optimal methodologies to measure Cathepsin D in breast cancers are controversial. Quantitative (immunoradiometric) and semiquantitative (immunohistochemical) assays for Cathepsin D expression were compared using 25 breast carcinomas. Immunohistochemical Cathepsin D results were derived using 3 differen...

In T47D breast cancer cell line, progestin (R5020) induces de novo synthesis of an alkaline phosphatase enzyme. Based on inhibitor profiles and antigenic specificity, it is apparent that this enzyme belongs to the class of membrane-associated tissue-unspecific alkaline phosphatases. Enzyme induction was uniquely specific to progestins and not alter...

The preparation of monoclonal antibodies (MAbs) against the human milk fat globule membrane with preferential binding to breast carcinoma cells is described. Using BALB/c mouse myeloma cells; inter-specific, intra-strain, and inter-strain hybridomas were isolated that identified three different components of the human milk fat globule of approximat...

Monoclonal antibodies (MAbs), recently produced against human progesterone receptors (PR), were used for immunocytochemical localization of PR. The specificity of the immunocytochemical assay for PR was demonstrated by incubation with control MAbs, preabsorption of MAbs with highly purified human PR, and by the cell and tissue distribution of the i...

The estrogen and progesterone receptor content of liver cytosol was measured in female patients with focal nodular hyperplasia associated with oral contraceptive use and compared with the receptor content of non-tumorous liver and of primary hepatocellular carcinomas. Receptors were found in very low concentrations or were not measurable at all. In...

A monoclonal antibody (323/A3) with a high degree of selectivity for binding to breast cancer cells was produced by immunization of mice with MCF-7 human breast cancer cells. The antigen recognized by 323/A3 on MCF-7 appears to be surface localized, and by enzyme-linked immunosorbent assay, the antibody was found to bind strongly with four of six b...

Six patients with inoperable, nonoperative, or recurrent meningiomas were treated with the antiestrogenic agent tamoxifen (Nolvadex) during an 8-12-month period. Computer tomographic, scintigraphic, and clinical evidence of an unspecific tumor response was only encountered in one patient after 4 months of therapy with tamoxifen. The 2-year results...

Specific uptake of tritiated 17 beta-oestradiol and R5020, a synthetic progestin, in breast cancer cell lines ( MCF7 and T47D) growing in monolayer culture in multiwell plates has been shown. Binding characteristics, calculated by Scatchard analysis, indicate the presence of steroid receptors of similar affinities and capacities to those already ob...

Biopsy specimens of tissue were taken from 32 invasive carcinomas of the breast, in each case from the centre of the tumour, the tumour margin and the surrounding mammary gland tissue. After preparation of a frozen section for tissue identification, the concentration of oestrogen and progesteron receptors (ER and PR, respectively) was determined in...

The triphenylethylene antiestrogen tamoxifen (TAM) is believed to exert its antitumor effect via the estrogen receptor (ER). To test this hypothesis and to differentiate between ER-mediated and general cytotoxic effects of TAM, the growth-inhibitory effects of TAM and its in vivo metabolite 4-hydroxytamoxifen (OH-TAM) have been studied in five cont...

Von 32 invasiven Mammakarzinomen wurden jeweils Gewebsproben aus Tumorzentrum, -rand und umliegendem Brustdrüsengewebe entnommen. Nach Anfertigung eines Gefrierschnittes zur Gewebeidentifikation wurden in jeder Probe mittels der Dextran-coated charcoal-Methode die Östrogen- (ER) und Progesteron- (PR) Rezeptorkonzentration bestimmt. Basierend auf di...

Multiple intratumoral tissue samples from the primary mass of 30 consecutive invasive breast cancer patients were assayed for estrogen receptor (ER) and progesterone receptor (PR) by the dextran-coated charcoal method following frozen section histopathological examination. Steroid receptor status of each sample was classified as positive (R+) or ne...

Analysis of estrogen receptor (ER) and progesterone receptor (PgR) in breast tumor biopsies has become routine practice in many clinical laboratories, primarily for two reasons: first, to help the clinician select the most effective therapy for patients with breast cancer, and, second, to compare the hormone receptor status of patients’ tumors with...

Estradiol and progesterone receptors were studied in 44 patients with meningiomas and correlated to the clinicopathological features and amount of preoperative corticosteroid therapy. Thirty-four (77%) of the meningiomas contained high titers of specific high-affinity cytosol [3H]promegestone (R 5020) binding sites (mean 2,902 fmol/g tumor; range 0...

Primary meningiomas have been grown in monolayer culture and tested for the presence of steroid hormone receptors and sensitivity to various steroids and steroid antagonists. None of the 10 solid tumors or the primary cultures derived from them contained estrogen receptors, either in the cytoplasm or in the nucleus. Progesterone receptors were pres...

Estrogen and progesterone receptor assays are performed in six laboratories with a standard dextran-coated method. Receptor concentrations are calculated by Scatchard plot analysis. A quality control study is carried out among these laboratories. The Ludwig Institute for Cancer Research, Inselspital, Bern, is responsible for coordinating the study...

A model system is presented to explain how tyrosinase, an enzyme unique to pigmented cells such as normal and malignant melanocytes can oxidize [3H]-estradiol to radiolabeled products which closely resemble the tight binding of [3H]-estradiol to estrogen receptor. In the model system studied, tyrosinase oxidized [2,4,6,7-3H]-estradiol to [3H]-water...

Tumor estradiol and progesterone binding sites were studied in 34 patients with meningioma. Twenty of the meningiomas contained very low titers (mean, 45 fmol/g of tumor; range, 0-201 fmol/g of tumor) of a nonspecific cytoplasmic [3H]estradiol binding component, whereas 26 of the tumors contained high titers of specific high-affinity cytosol [3H]pr...