Job demands and job performance: the mediating effect of psychological and physical strain and the moderating effect of role clarity

The aims of the present study were twofold: First, in differentiating between specific job characteristics, the authors examined the moderating influence of role clarity on the relationship between job demands and psychological and physical strain. Second, in providing a more comprehensive link between job demands and job performance, the authors examined strain as a mediator of that relationship. Participants were 1,418 Army cadets attending a 35-day assessment center. Survey data were collected on Day 26 of the assessment center and performance ratings were assessed throughout the assessment center period by expert evaluators. Role clarity was found to moderate the job demands-strain relationship. Specifically, cadets experiencing high demands reported less physical and psychological strain when they reported high role clarity. Moreover, psychological strain significantly mediated the demands-performance relationship. Implications are discussed from theoretical and applied perspectives.     

Extragonadal germ cell tumors: a review with emphasis on pathologic features, clinical prognostic variables, and differential diagnostic considerations

Extragonadal germ cell tumors (GCTs) are relatively uncommon, but represent 1% to 5% of all GCTs. Their morphology varies widely and includes mature teratoma, immature teratoma, seminoma, yolk sac tumor, embryonal carcinoma, choriocarcinoma, and mixed GCTs. Noncentral nervous system extragonadal GCTs are found in a variety of anatomic locations, but most commonly affect the mediastinum and sacrococcygeal region. Predicting behavior in these tumors can be confusing because it is based on a combination of varying factors including patient age, histologic subtype, anatomic site, and clinical stage. This review attempts to dissect these issues by separating the discussion into 3 age groups: neonatal (congenital), children (prepubertal), and adult (postpubertal). Within each individual age group, we cover the significance of anatomic site, morphology, and staging parameters. In addition, we discuss the spectrum of associated secondary malignancies and their impact on patient outcome. Finally, we provide a detailed survey of differential diagnostic considerations grouped by anatomic site.     

Inverted-U dopamine D1 receptor actions on prefrontal neurons engaged in working memory

Dopamine (DA) D1 receptor (D1R) stimulation in prefrontal cortex (PFC) produces an 'inverted-U' dose-response, whereby either too little or too much D1R stimulation impairs spatial working memory. This response has been observed across species, including genetic linkages with human cognitive abilities, PFC activation states and DA synthesis. The cellular basis for the inverted U has long been sought, with in vitro intracellular recordings supporting a variety of potential mechanisms. The current study demonstrates that the D1R agonist inverted-U response can be observed in PFC neurons of behaving monkeys: low levels of D1R stimulation enhance spatial tuning by suppressing responses to nonpreferred directions, whereas high levels reduce delay-related firing for all directions, eroding tuning. These sculpting actions of D1R stimulation are mediated in monkeys and rats by cyclic AMP intracellular signaling. The evidence for an inverted U at the cellular level in behaving animals promises to bridge in vitro molecular analyses with human cognitive experience.     

Allelic 'choice' governs somatic hypermutation in vivo at the immunoglobulin kappa-chain locus

Monoallelic demethylation and rearrangement control allelic exclusion of the immunoglobulin kappa-chain locus (Igk locus) in B cells. Here, through the introduction of pre-rearranged Igk genes into their physiological position, the critical rearrangement step was bypassed, thereby generating mice producing B cells simultaneously expressing two different immunoglobulin-kappa light chains. Such 'double-expressing' B cells still underwent monoallelic demethylation at the Igk locus, and the demethylated allele was the 'preferred' substrate for somatic hypermutation in each cell. However, methylation itself did not directly inhibit the activation-induced cytidine-deaminase reaction in vitro. Thus, it seems that the epigenetic mechanisms that initially bring about monoallelic variable-(diversity)-joining rearrangement continue to be involved in the control of antibody diversity at later stages of B cell development.     

Epithelial cells trigger frontline immunoglobulin class switching through a pathway regulated by the inhibitor SLPI

Epithelial cells (ECs) transport class-switched immunoglobulin G (IgG) and IgA antibodies across mucous membranes. Whether ECs initiate class switching remains unknown. Here we found that ECs lining tonsillar crypts formed pockets populated by B cells expressing activation-induced cytidine deaminase (AID), an enzyme associated with ongoing class switching. ECs released B cell-activating AID-inducing factors after sensing microbial products through Toll-like receptors. The resulting class switching was amplified by thymic stromal lymphopoietin, an epithelial interleukin 7-like cytokine that enhanced the B cell 'licensing' function of dendritic cells, and was restrained by secretory leukocyte protease inhibitor, an epithelial homeostatic protein that inhibited AID induction in B cells. Thus, ECs may function as mucosal 'guardians' orchestrating frontline IgG and IgA class switching through a Toll-like receptor-inducible signaling program regulated by secretory leukocyte protease inhibitor.NOTE: In the version of this article initially published online, the middle label above Figure 6c is incorrect. The correct label should be 'BAFF'. The error has been corrected for all versions of the article.     

Small bowel obstruction in pregnancy

Background Intestinal obstruction in pregnancy is rare. Symptoms are often unspecific and a high level of suspicion is essential for early diagnosis. Fetal and maternal mortality rates are higher during pregnancy due to delay in diagnosis. Case A 31-year-old primigravida with a history of abdominal surgery was admitted because of worsening abdominal pain, abdominal distension and elevated pancreatic enzymes. Ultrasound showed dilated small bowel loops. Explorative laparotomy revealed a small bowel obstruction with partial bowel necrosis caused by a single adhesion. A jejuno-jejunostomy was performed. Five days later, she developed peritonitis. A secondary laparotomy and caesarean section were done. Conclusion In spite of timely diagnosis and prompt surgical intervention, our case was still complicated by peritonitis and early delivery. This underlines the necessity of immediate clinical suspicion. Small bowel obstruction should be considered in differential diagnosis of pregnant patients with a history of abdominal surgery.