Mendelian randomization supports causality between maternal hyperglycemia and epigenetic regulation of leptin gene in newborns

Leptin is an adipokine that acts in the central nervous system and regulates energy balance. Animal models and human observational studies have suggested that leptin surge in the perinatal period has a critical role in programming long-term risk of obesity. In utero exposure to maternal hyperglycemia has been associated with increased risk of obesity later in life. Epigenetic mechanisms are suspected to be involved in fetal programming of long term metabolic diseases. We investigated whether DNA methylation levels near LEP locus mediate the relation between maternal glycemia and neonatal leptin levels using the 2-step epigenetic Mendelian randomization approach. We used data and samples from up to 485 mother-child dyads from Gen3G, a large prospective population-based cohort. First, we built a genetic risk score to capture maternal glycemia based on 10 known glycemic genetic variants (GRS10) and showed it was an adequate instrumental variable (β = 0.046 mmol/L of maternal fasting glucose per additional risk allele; SE = 0.007; P = 7.8 × 10(-11); N = 467). A higher GRS10 was associated with lower methylation levels at cg12083122 located near LEP (β = -0.072 unit per additional risk allele; SE = 0.04; P = 0.05; N = 166). Direction and effect size of association between the instrumental variable GRS10 and methylation at cg12083122 were consistent with the negative association we observed using measured maternal glycemia. Lower DNA methylation levels at cg12083122 were associated with higher cord blood leptin levels (β = -0.17 log of cord blood leptin per unit; SE = 0.07; P = 0.01; N = 170). Our study supports that maternal glycemia is part of causal pathways influencing offspring leptin epigenetic regulation.

Review of a mock research protocol in functional neuroimaging by Canadian research ethics boards

OBJECTIVE

To examine how research ethics boards (REBs) review research projects in emerging disciplines such as functional neuroimaging.

DESIGN

To compare the criteria applied and the decisions reached by REBs that reviewed the same mock research protocol in functional neuroimaging.

PARTICIPANTS

44 Canadian biomedical REBs, mostly working in public university or hospital settings.

MAIN MEASUREMENTS

The mock research protocol "The Neurobiology of Social Behavior" included several ethical issues operating at all three levels: personal, institutional and social. Data consisting of responses to closed questions were analysed quantitatively. Qualitative analysis of open-question responses used mixed classification.

RESULTS

Similar criteria were used by most participating REBs. Yet the project was unconditionally approved by 3 REBs, approved conditionally by 10 and rejected by 30.

CONCLUSIONS

The results point to the difficulty for REBs of reviewing all kinds of research projects, regardless of field, by relying on international and national norms framed in general terms and a possible variation between REBs in the interpretation of their mandate for the protection of research subjects.

Differences in diabetic co-morbidity between Aboriginal and non-Aboriginal people living in Bella Coola, Canada

INTRODUCTION

OBJECTIVES

(1) To identify which medical disorders are significantly associated with being a diabetic in the setting of an isolated, rural community; and (2) to determine if there are differences between Aboriginal and non-Aboriginal diabetics.

METHODS

DESIGN

population based retrospective chart review.

STUDY POPULATION

people living in the Bella Coola Valley, Canada, and having a chart at the Bella Coola Medical Clinic as at September 2001.

MAIN OUTCOME MEASURES

known diabetes related co-morbidity (retinopathy, nephropathy, coronary artery disease, peripheral vascular disease, neuropathy).

RESULTS

There were 126 adult (>18 years old) diabetics living in the Bella Coola Valley. Prevalence rates for history of alcohol issues, retinopathy, coronary artery disease, cerebrovascular disease, peripheral vascular disease, peripheral neuropathy, hypertension, hypercholesterolemia, and nephropathy were 44%, 14%, 19%, 8%, 7%, 10%, 54%, 47%, and 7% respectively. For the 1597 non-diabetics living in the Bella Coola Valley, respective prevalence rates for these same co-morbidities were 20%, 0.3%, 2%, 1.5%, 1%, 1%, 10%, 6%, and 0.6%. The study did not demonstrate that Aboriginal people living in the Bella Coola Valley have an increased prevalence of diabetes associated co-morbidities over and above that found in the non-Aboriginal diabetic population. This was despite the fact the smoking rate was higher in the Aboriginal population.

CONCLUSIONS

The development of diabetes in both Aboriginal and non-Aboriginal people living in the Bella Coola Valley was clearly associated with the presence of multiple co-morbidities, including hypertension, hypercholesterolemia, coronary artery disease, cerebrovascular disease, and neuropathy. Rates of diabetes associated co-morbidities were similar for both Aboriginal and non-Aboriginal diabetic populations. The authors speculate that a diet rich in fish oils (omega-3 fatty acids) accounted for the lower than expected rates of cardiovascular disease among this Aboriginal population.

No detrimental effect from chronic exposure to buprenorphine on corticosteroid-binding globulin and corticosensitive immune parameters

Opioid drugs reportedly regulate the immune system via their effects on the hypothalamic- pituitary-adrenal (HPA) axis. The present study was carried out to assess the effects of chronic exposure to buprenorphine on HPA axis activation, corticosteroid-binding globulin (CBG), the main glucocorticoid (GC) carrier, and the immune system. Results show that buprenorphine, delivered by osmotic pump subcutaneously in C57BL/6 male mice during a 10-day period, caused a marked decrease in total corticosterone (CORT) levels at day 1 of exposure. CORT levels then increased with maximal values observed at day 5 of exposure. After day 5, total CORT levels gradually decreased and returned to control values. No significant changes were observed in CBG protein levels and mRNA expression in the liver. Since CBG levels remained unchanged, the percentage of free CORT values in buprenorphine mice did not differ from control values. Thus, the variations observed in the amount of free CORT were related only to changes measured in total CORT. These endocrine changes did not have a significant impact on the immune parameters measured. Total CD(4)+ and CD(8)+ splenic and thymic populations were not modulated by buprenorphine. However, splenocytes from mice exposed to buprenorphine after 5 days exhibited greater proliferation upon anti-TCR monoclonal antibody stimulation than saline-exposed mice. These results indicate that buprenorphine can be safely used because it did not have significant effects on GC availability for immune corticosensitive cells.

Changes in the components of moral reasoning during students' medical education: a pilot study

INTRODUCTION

Many authors are concerned by students' moral reasoning not developing normally during medical education.

AIM

This study is concerned with how the components of student' moral reasoning are affected by their medical studies.

METHODS

Ninety-two medical students were tested on entry into first year and on finishing third year, to determine evolutionary changes in their moral reasoning. Changes in their use of arguments specific to each stage of moral development were measured.

RESULTS

Significant changes were observed in the weighted global score (-18.14 +/- 59.17, P = 2.8%). Changes in global score correlated with changes in stages of moral reasoning. The multivariate structure of moral reasoning was reorganised into two principal components, which, respectively, explained almost 82% (first year) and 72% (third year) of the total variability in scores. Moral reasoning stages characterized by law-and-order and social-contract/legalistic orientations proved important for explaining the variability in students' moral reasoning at the start of medical training, while instrumental-relativist and interpersonal-concordance orientations explained variability post third year.

CONCLUSIONS

Students restructure their handling of ethical questions by using arguments with more instrumental-relativist and interpersonal-concordance orientations, rather than those of the more desirable law-and-order or social-contract/legalistic type. To assess better the skills required for moral reasoning, a more sophisticated approach is needed than that of a simple measure of improvement/stagnation/deterioration.