Indirect immunoperoxidase localization of aflatoxin B1 in rat liver

Aflatoxin B2a (AFB2a) antibody was used as a histochemical probe in the indirect immunoperoxidase localization of aflatoxin B1 (AFB1) bound to rat liver. The efficacy of the indirect method was initially demonstrated by detecting AFB1 covalently bound to DNA in an enzyme-linked immunosorbent assay. AFB1-modified DNA was attached to a polystyrene microtissue culture plate (solid phase) and then subjected to sequential incubation with AFB2a antiserum followed by goat anti-rabbit peroxidase conjugate. Assays for bound peroxidase revealed that the AFB2a antiserum could be diluted 200,000-fold and still yield a signal-to-noise ratio of 10 when compared to an unmodified DNA control. When the same indirect immunoperoxidase protocol was applied to the light-microscopic localization of AFB1 in liver sections of rats treated in vivo with the mycotoxin, bound toxin could be identified in excellent detail in tissues fixed with periodate-lysine-paraformaldehyde and embedded in glycol methacrylate, but was detectable with only poor resolution in unfixed cryostat sections. Peroxidase-positive reactions in hepatocytes typically exhibited strong nuclear and relatively lighter cytoplasmic staining. Greater concentrations of peroxidase-positive hepatocytes were detected in the periportal area than in the area of the central vein, suggesting a circulatory pattern for AFB1 binding in the liver.     

The impact of learning space on teaching behaviors

In traditional classrooms the teacher stands at the front of the room and rows of students face forward. Many academic institutions have chosen to renovate traditional classrooms and turn them into spaces more conducive to collaboration. Few data exist supporting the notion that changing physical space affects teaching behaviors. We used a mixed method design to evaluate teaching behaviors in traditional and collaborative classrooms. Expert teachers viewed classroom videos and described behaviors observed. After qualitative analysis, we identified the frequency of themes and found no significant differences in teaching behaviors in traditional versus collaborative classrooms.     

Genetics in critical care: a toolbox

Becoming comfortable with the onslaught of genetic information requires a familiarity with genetics terminology and basic molecular genetics. Caring for the genetic health of our patients requires an additional appreciation of genetic testing and screening issues and new areas of study with strange-sounding names, such as proteomics, nutrigenomics, and epigenetics. This article provides an overview of basic genetic principles and terminology with applications to critical care patients. It lays a foundation to support understanding of the other articles in this issue. An appreciation of genetics (the study of heredity) and genomics (the study of the interaction of genes within an organism) has an important place in the knowledge base of every critical care clinician.     

The genetics of cardiac arrhythmias

Cardiac rhythm problems result in high levels of morbidity and mortality, with sudden arrhythmic death claiming approximately 300,000 lives in the United States each year. Investigations into the genetic contributions to rhythm and conduction disorders have found genes or loci associated with primary rhythm/conduction disorders such as familial atrial fibrillation and atrio-ventricular block, underscoring the importance of collecting a thorough family history. Combinations of single or multiple genes and environmental risk factors may place only certain family members at risk. Some cardiac muscle problems, such as cardiomyopathy, predispose to arrhythmia and have documented genetic components. Primary health care providers need current knowledge of genetic contributions to rhythm/conduction problems so that family members at risk can be identified early and cared for appropriately. This article provides an overview of the genetic contributions to cardiac rhythm and conduction problems.     

Genetic and Genomic Testing in Clinical Practice: What You Need to Know

The clinical applications of genetic testing are growing rapidly and they now account for a significant percentage of total laboratory testing procedures. Many clinicians are uncomfortable with the types and applications of genetic tests and the dependable resources that are available for self‐education. Furthermore, Direct to Consumer genetic testing has presented several challenges to healthcare providers as consumers now have an access to tests that they may not fully understand and results they may act upon inappropriately. This article presents some of the issues and resources to help nurses navigate this changing landscape.     

Aversive exchanges with peers and adjustment during early adolescence: Is disclosure helpful?

We examined the relationship between the frequency of four types of aversive exchanges with peers (teased, threatened, hit, excluded), disclosure, and psychological distress in a sample of 130 early adolescents (65 boys, 65 grils). Most (73%) reported at least one aversive exchange with a peer during the 3-month target period. Many reported that they did not talk to anyone about these exchanges. When disclosure occurred, other adolescents were more likely than adults to be chosen as confidants. More frequent aversive exchanges and non-disclosure of these events were related to higher self-reported loneliness for boys and girls. A similar pattern was found for girls only using mothers' ratings of the adolescents' internalizing and externalizing symptoms. Western Psychiatric Institute and Hospital This study was supported in part by National Institute of Mental Health Grant MH46996 (E. Vernberg, PI), and by grants to the first author from the University Research Council of the University of Miami.     

Distribution of total progesterone receptor levels in various segments and tissues of the normal human uterus: the effect of short-term estrogen administration

Total progesterone receptor levels (TRP) were measured in various tissues and segments of normal human uteri in basal conditions (late proliferative phase, control group, n = 6) and after short term estrogen administration (test group, n = 8). Similar trends of distribution were observed in both groups in basal endometrial TRP levels along the longitudinal axis, i.e. the highest levels were found at the height of the body and the lowest at the height of the internal os. Differences were found in the trends of distribution of the TRP levels between the two groups along the transverse axis of the uterus at the height of the fundus. In the control group TRP levels in the functional endometrium were higher than those in the basal endometrium and myometrium. In the test group, however, the trend was reversed. Since the RP is estradiol induced and dependent, these results indicate the possibility of a selective estrogen effect on various segments or tissues in the human uterus.