Molecular epidemiologic studies of polycyclic aromatic hydrocarbon-DNA adducts and breast cancer

We review our studies on the role of polycyclic aromatic hydrocarbon (PAH)-DNA adducts in breast cancer. Additionally we report on analyses of the reliability of the scoring procedures used with immunohistochemical assay for PAH-DNA adducts and of potential bias arising from the use of benign breast disease (BBD) controls. We conducted a case-control study utilizing two control groups: BBD controls who donated tissue and blood samples, and healthy controls who donated blood samples. In comparisons of tumor tissue from cases and benign tissue from BBD controls, increasing adduct levels were significantly associated with case-control status [odds ratio (OR) = 2.40, 95% confidence interval (CI) 1.18-4.92], whereas in comparisons of nontumor tissue from cases and benign tissue from BBD controls the association was nonsignificant (OR = 1.97, 95% CI 0.94-4.17). We also show among cases, but not among BBD controls, that the GSTM1 null genotype is associated with increased adduct levels in breast tissue. Our reliability study found the scoring procedures used with the immunohistochemical assay to have high reliability, 0.93 in nontumor, 0.82 in tumor, and 0.74 in benign tissues. However, we found that the technician significantly contributed to the total variability of a series of data. Finally, we did not find a consistent bias to the null associated with the use of BBD controls; however, BBD controls may overestimate the prevalence of family history of breast cancer compared to that of healthy controls (18% vs.14%). We hypothesize that the higher prevalence results from a referral bias and discuss how this may influence our results.     

A brain‐potential correlate of task‐set conflict

Brain‐potential correlates of response conflict are well documented, but those of task conflict are not. Task‐switching studies have suggested a plausible correlate of task conflict—a poststimulus posterior negativity—however, in such paradigms the negativity may also reflect poststimulus task‐set reconfiguration postulated in some models. Here, participants alternated between single‐task blocks of classifying letters and digits; hence, no within‐block task‐set reconfiguration was required. Presenting letters alongside digits slowed responses to the digits and elicited an ERP negativity from ～350 ms, relative to task‐neutral symbols presented alongside digits, consistent with task conflict. The negativity was also present for congruent digit‐letter stimuli; this and the lack of behavioral response congruency effects indicate conflict at the level of task‐set rather than response selection.     

Maternal psychological growth following childbirth

Although maternal postpartum mental health has been extensively studied, rather little is known regarding the factors that may facilitate psychological growth following childbirth. The present study set forth to examine various pre-birth, birth, and post-birth correlates of overall psychological growth and growth domains in postpartum women, assessed within the first months following childbirth. A sample of 428 women completed self-report measures pertaining to psychological growth, mental health, maternal attachment, and childbirth characteristics. We found that the majority of women reported psychological growth following childbirth, with those experiencing stressors in childbirth reporting the highest levels of appreciation for life. In regression analyses, postpartum factors were significantly associated with overall growth and growth domains, taking into account other factors. The more the childbirth was perceived as central to the mothers’ identity and the better the maternal attachment was to the child, the higher levels of growth. Growth was also negatively related to endorsement of childbirth PTSD. Background factors, such as maternal age, education, and prior mental health, were associated with specific growth domains, although the association was small and there was no association with overall growth. Post-birth factors are important in ensuing psychological growth in the first months following birth. Attention to opportunities of growth following childbirth is warranted in clinical care, in particular following traumatic childbirth.

     

Retinal cone photoreceptor distribution in the American black bear (Ursus americanus)

The distribution of cone photoreceptor subtypes (important for color vision and vision quality) varies widely in different carnivore species, but there have been limited studies on bear (ursid) cone distribution. A previous behavioral study suggests that American black bears (Ursus americanus) are dichromatic, indicating that they possess two cone subtypes, although the retinal distribution of cones is unknown. The purpose of this study was to examine the subtype and topography of cones in American black bear retinas to further predict the nature of their color vision and image resolution. We studied 10 eyes from seven individual legally hunted black bears in northeastern North Carolina. Cryosections and retinal wholemounts were labeled using antibodies targeting two cone opsin subtypes: long/medium (L/M) wavelength sensitive and short (S) wavelength sensitive. Cones in fluorescent microscopy images were counted and density maps were created for retinal wholemounts. The black bear retina contains both cone subtypes and L/M cones outnumber S cones by at least 3:1, a finding confirmed in retinal frozen sections. There are higher concentrations of S cones present than typically seen in other carnivores with some evidence for co-expression of L/M and S cones. A cone-dense area centralis is present dorsotemporal to the optic nerve, similar to other carnivores. These results confirm that American black bears are predicted to have a dichromatic vision with high acuity indicated by the presence of a dorsotemporally located area centralis.     

Inflammation and fibrosis in chronic liver diseases including nonalcoholic fatty liver disease and hepatitis C

At present chronic liver disease(CLD),the third commonest cause of premature death in the United Kingdom is detected late,when interventions are ineffective,resulting in considerable morbidity and mortality.Injury to the liver,the largest solid organ in the body,leads to a cascade of inflammatory events.Chronic inflammation leads to the activation of hepatic stellate cells that undergo transdifferentiation to become myofibroblasts,the main extra-cellular matrix producing cells in the liver;over time increased extra-cellular matrix production results in the formation of liver fibrosis.Although fibrogenesis may be viewed as having evolved as a“wound healing”process that preserves tissue integrity,sustained chronic fibrosis can become pathogenic culminating in CLD,cirrhosis and its associated complications.As the reference standard for detecting liver fibrosis,liver biopsy,is invasive and has an associated morbidity,the diagnostic assessment of CLD by non-invasive testing is attractive.Accordingly,in this review the mechanisms by which liver inflammation and fibrosis develop in chronic liver diseases are explored to identify appropriate and meaningful diagnostic targets for clinical practice.Due to differing disease prevalence and treatment efficacy,disease specific diagnostic targets are required to optimally manage individual CLDs such as non-alcoholic fatty liver disease and chronic hepatitis C infection.To facilitate this,a review of the pathogenesis of both conditions is also conducted.Finally,the evidence for hepatic fibrosis regression and the mechanisms by which this occurs are discussed,including the current use of antifibrotic therapy.     

Sex, stress and social status: Patterns in fecal testosterone and glucocorticoid metabolites in male Ethiopian wolves

Ethiopian wolves, Canis simensis, live in large multi-male family packs, where males are philopatric and do not disperse. Within a pack, mating and breeding is largely monopolized by the dominant male and female, although extra-pack copulations are common, and subordinate males may sire pups in neighboring packs. Regardless of paternity, all males in a pack help rear the pups. We non-invasively studied patterns in fecal testosterone and glucocorticoid metabolite concentrations using radioimmunoassays of fecal samples collected from nine wild male Ethiopian wolves between August 2007 and February 2008. We tested the predictions of the Challenge Hypothesis, namely that fecal testosterone metabolite concentrations would be higher during the annual mating season, which is the portion of the reproductive cycle when mating and increased aggression typically occur, and lower when there were pups in the pack for which to care. Contrary to the predictions of the Challenge Hypothesis, we did not detect patterns in fecal testosterone metabolite concentrations associated with reproductive stage during our study period. Similarly, we found no patterns associated with reproductive stage in male fecal glucocorticoid metabolite concentrations. Dominant males had higher average fecal testosterone and glucocorticoid metabolite concentrations than did subordinates, which may be related to higher rates of aggression and mate guarding in dominant males of group-living canids, a pattern also reported in African wild dogs, Lycaon pictus.