Erasure of DNA methylation in rat fetal germ cells is sex-specific and sensitive to maternal high-fat diet.

In mammals, DNA methylation (DNAme) erasure and reinstatement during embryo development and germline establishment are sensitive to the intrauterine environment. Maternal intake of a high-fat diet (HFD), associated with excessive gestational weight gain, has transgenerational effects on offspring health, which may be mediated by changes in DNAme in the germline. Here, we tested the impact of a maternal HFD on embryonic germline DNAme erasure using a rat strain that expresses green fluorescent protein specifically in germ cells. DNAme was analysed by methyl-seq capture in germ cells collected from male and female F1 gonads at gestational day 16. Our data show that although HFD induced global hypomethylation in both sexes, DNAme erasure in female germ cells was more advanced compared to male germ cells. The delay in DNAme erasure in males and the greater impact of HFD suggest that male germ cells are more vulnerable to alterations by exogenous factors.

Developmental genome-wide DNA methylation asymmetry between mouse placenta and embryo.

In early embryos, DNA methylation is remodelled to initiate the developmental program but for mostly unknown reasons, methylation marks are acquired unequally between embryonic and placental cells. To better understand this, we generated high-resolution DNA methylation maps of mouse mid-gestation (E10.5) embryo and placenta. We uncovered specific subtypes of differentially methylated regions (DMRs) that contribute directly to the developmental asymmetry existing between mid-gestation embryonic and placental DNA methylation patterns. We show that the asymmetry occurs rapidly during the acquisition of marks in the post-implanted conceptus (E3.5-E6.5), and that these patterns are long-lasting across subtypes of DMRs throughout prenatal development and in somatic tissues. We reveal that at the peri-implantation stages, the de novo methyltransferase activity of DNMT3B is the main driver of methylation marks on asymmetric DMRs, and that DNMT3B can largely compensate for lack of DNMT3A in the epiblast and extraembryonic ectoderm, whereas DNMT3A can only partially compensate in the absence of DNMT3B. However, as development progresses and as DNMT3A becomes the principal de novo methyltransferase, the compensatory DNA methylation mechanism of DNMT3B on DMRs becomes less effective.

Stability of the human sperm DNA methylome to folic acid fortification and short-term supplementation.

STUDY QUESTION: Do short-term and long-term exposures to low-dose folic acid supplementation alter DNA methylation in sperm? SUMMARY ANSWER: No alterations in sperm DNA methylation patterns were found following the administration of low-dose folic acid supplements of 400 µg/day for 90 days (short-term exposure) or when pre-fortification of food with folic acid and post-fortification sperm samples (long-term exposure) were compared. WHAT IS KNOWN ALREADY: Excess dietary folate may be detrimental to health and DNA methylation profiles due to folate's role in one-carbon metabolism and the formation of S-adenosyl methionine, the universal methyl donor. DNA methylation patterns are established in developing male germ cells and have been suggested to be affected by high-dose (5 mg/day) folic acid supplementation. STUDY DESIGN, SIZE, DURATION: This is a control versus treatment study where genome-wide sperm DNA methylation patterns were examined prior to fortification of food (1996-1997) in men with no history of infertility at baseline and following 90-day exposure to placebo (n = 9) or supplement containing 400 µg folic acid/day (n = 10). Additionally, pre-fortification sperm DNA methylation profiles (n = 19) were compared with those of a group of post-fortification (post-2004) men (n = 8) who had been exposed for several years to dietary folic acid fortification. PARTICIPANTS/MATERIALS, SETTING, METHODS: Blood and seminal plasma folate levels were measured in participants before and following the 90-day treatment with placebo or supplement. Sperm DNA methylation was assessed using the whole-genome and genome-wide techniques, MassArray epityper, restriction landmark genomic scanning, methyl-CpG immunoprecipitation and Illumina HumanMethylation450 Bead Array. MAIN RESULTS AND THE ROLE OF CHANCE: Following treatment, supplemented individuals had significantly higher levels of blood and seminal plasma folates compared to placebo. Initial first-generation genome-wide analyses of sperm DNA methylation showed little evidence of changes when comparing pre- and post-treatment samples. With Illumina HumanMethylation450 BeadChip arrays, no significant changes were observed in individual probes following low-level supplementation; when compared with those of the post-fortification cohort, there were also few differences in methylation despite exposure to years of fortified foods. LARGE SCALE DATA: Illumina HumanMethylation450 BeadChip data from this study have been submitted to the NCBI Gene Expression Omnibus under the accession number GSE89781. LIMITATIONS, REASONS FOR CAUTION: This study was limited to the number of participants available in each cohort, in particular those who were not exposed to early (pre-1998) fortification of food with folic acid. While genome-wide DNA methylation was assessed with several techniques that targeted genic and CpG-rich regions, intergenic regions were less well interrogated. WIDER IMPLICATIONS OF THE FINDINGS: Overall, our findings provide evidence that short-term exposure to low-dose folic acid supplements of 400 µg/day, over a period of 3 months, a duration of time that might occur during infertility treatments, has no major impact on the sperm DNA methylome. STUDY FUNDING/COMPETING INTERESTS: This work was supported by a grant to J.M.T. from the Canadian Institutes of Health Research (CIHR: MOP-89944). The authors have no conflicts of interest to declare.

Temporal and geographic clustering of polyomavirus-associated olfactory tumors in 10 free-ranging raccoons (Procyon lotor).

Reports of primary nervous system tumors in wild raccoons are extremely rare. Olfactory tumors were diagnosed postmortem in 9 free-ranging raccoons from 4 contiguous counties in California and 1 raccoon from Oregon within a 26-month period between 2010 and 2012. We describe the geographic and temporal features of these 10 cases, including the laboratory diagnostic investigations and the neuropathologic, immunohistochemical, and ultrastructural characteristics of these tumors in the affected animals. All 9 raccoons from California were found within a localized geographic region of the San Francisco Bay Area (within a 44.13-km radius). The tight temporal and geographic clustering and consistent anatomic location in the olfactory system of tumor types not previously described in raccoons (malignant peripheral nerve sheath tumors and undifferentiated sarcomas) strongly suggest either a common cause or a precipitating factor leading to induction or potentiation of neuro-oncogenesis and so prompted an extensive diagnostic investigation to explore possible oncogenic infectious and/or toxic causes. By a consensus polymerase chain reaction strategy, a novel, recently reported polyomavirus called raccoon polyomavirus was identified in all 10 tumors but not in the normal brain tissue from the affected animals, suggesting that the virus might play a role in neuro-oncogenesis. In addition, expression of the viral protein T antigen was detected in all tumors containing the viral sequences. We discuss the potential role of raccoon polyomavirus as an oncogenic virus.

Stress fracture risk factors in basic combat training.

This study examined demographic and physical risk factors for stress fractures in a large cohort of basic trainees. New recruits participating in US Army BCT from 1997 through 2007 were identified, and birth year, race/ethnicity, physical characteristics, body mass index, and injuries were obtained from electronic databases. Injury cases were recruits medically diagnosed with inpatient or outpatient stress fractures. There were 475 745 men and 107 906 women. Stress fractures incidences were 19.3 and 79.9 cases/1 000 recruits for men and women, respectively. Factors that increased stress fracture risk for both men and women included older age, lower body weight, lower BMI, and race/ethnicity other than black. Compared to Asians, those of white race/ethnicity were at higher stress fractures risk. In addition, men, but not women, who were taller or heavier were at increased stress fracture risk. Stress fracture risk generally increased with age (17-35 year range) at a rate of 2.2 and 3.9 cases/1 000 recruits per year for men and women, respectively. This was the largest sample of military recruits ever examined for stress fractures and found that stress fracture risk was elevated among recruits who were female, older, had lower body weight, had lower BMI, and/or were not of black race/ethnicity.

A focus group study of DES daughters: implications for health care providers.

A focus group study of women exposed to diethylstilbestrol (DES) in utero (DES daughters) was conducted to gain understanding about exposure to this drug from a patient perspective. Focus group participants reported that learning about their DES exposure was devastating; they experienced strains in their family relationships, emotional shock, a feeling that their health concerns were not appreciated by others and, to some degree, a sense of social isolation. Although many were aware of the need for special gynecological exams and high-risk prenatal care, they were frustrated by what they felt was a lack of reliable and clear information about the effects of DES exposure. Most expressed questions and anxiety about their health. Many found their communication with physicians about their DES exposure unsatisfying. They felt that physicians lacked information about the long-term health effects of DES exposure and as a result did not give them accurate information. Furthermore, they felt that physicians were dismissive of their concerns and often gave what they felt to be false reassurances. Consequently, the women developed an enduring distrust of the medical profession. The results of the study suggest implications for the delivery of health care to DES daughters.

Conceptualizing menopause and midlife: Chinese American and Chinese women in the US.

OBJECTIVES: The purpose of this qualitative project was to describe and examine expectations and experiences of menopause and midlife in pre- and postmenopausal Chinese American and Chinese women in the United States. METHODS: Four focus groups were formed from a total of 44 women: two groups of premenopausal Chinese/Chinese American women (one conducted in English and one in Cantonese) and two groups of postmenopausal Chinese/Chinese American women (one conducted in English and one in Cantonese). Qualitative data, in the form of transcripts, were interpreted using text-based content analysis. RESULTS: The major thematic findings were: meanings of menopause are inextricably bound with meanings of midlife; the borders and timing of the menopausal transition are ambiguous; the menopausal transition represents a natural progression through the life cycle; the expectations of the premenopausal women did not match the experiences of the postmenopausal women; menopause is viewed as a marker for aging; and the menopausal transition must be prepared for and managed. CONCLUSIONS: Study findings indicate that the participants did not share the strictly medicalized view of menopause as a discrete, biological entity. Menopause was typically described as a natural transition that was virtually interchangeable with midlife. While most of the participants characterized menopause as signaling the end of fertility and virtually synonymous with old age, some women described it as a new opportunity and a second chance at life. Participants felt a sense of their own agency in addressing what they viewed as a complex life stage, the experience of which could be manipulated.

Perceptions of insanity based on occupation of defendant and seriousness of crime.

The purpose was to estimate the relationship between a defendant's stated intelligence on perceptions of his sanity and responsibility. This analog study was a 2 (occupation of defendant) x 2 (seriousness of outcome) between-subjects design. A scenario involving an insanity defense was read by 190 college students who then answered a 12-item questionnaire. The hypothesis that participants would attribute less responsibility to less intelligent defendants than to more intelligent ones was partially supported. Belief in a Just World moderated these evaluations. Seriousness of outcome influenced men's perceptions of the defendant's insanity, responsibility, and sentence, but not women's. Participants seemed to be more willing to accept the possibility that the defendant was insane if the outcome of his crime was not serious.

Is there a physician union in your future?

Physician unions are in the news. Patient management and patient care decisions are increasingly being taken out of the hands of physicians and put into the hands of "The Suits." To take their case for a return to physician-driven patient care to the people, some physicians are joining unions. Some are even collectively bargaining for salary and other issues that are historically more closely associated with unions. The simple fact is that physician unions exist and the number of physicians joining them is expected to increase. What are the pros and cons of unionization? What motivates physicians to join unions, and what potential negative and positive factors are associated with physician unionization? This article reviews the pros and cons and the issues related to physician unions, for physicians attempting to answer the question, "Is there a union in my future?"

Using process data to explain outcomes. An illustration from the Child and Adolescent Trial for Cardiovascular Health (CATCH).

The purpose of this article is to illustrate the use of process evaluation for understanding study outcomes. Data from the Child and Adolescent Trial for Cardiovascular Health (CATCH), a large school-based field trial, are used. Teacher characteristics, measures of classroom curriculum implementation, and competing influences are linked to changes in dietary knowledge, intentions, and self-efficacy of students in the intervention schools. Multiple regression analyses indicate that teacher characteristics did not predict program implementation. Teacher characteristics and program fidelity, or the number of modifications made to the classroom curriculum during implementation, had direct and independent effects on student outcomes.

A self-efficacy scale for HIV risk behaviors: development and evaluation.

To measure self-efficacy with respect to risk behaviors for HIV infection, a set of questionnaire items was developed regarding condom use, drug use with friends, and negotiations with potential sex partners. These items were tested with a sample of Latinos aged 14 to 22 years in two New England cities. A nine-item self-efficacy scale was found to have a high level of internal consistency (Cronbach's alpha = .77). Reliability coefficients were similar for men, women, and both English- and Spanish-speaking respondents. Strong associations with recent performance accomplishments, as specified in Bandura's social cognitive theory, support the construct validity of the scale.