Differential influence of safe versus threatening facial expressions on decision-making during an inhibitory control task in adolescence and adulthood.

Social cognition matures dramatically during adolescence and into early adulthood, supported by continued improvements in inhibitory control. During this time, developmental changes in interpreting and responding to social signals such as facial expressions also occur. In the present study, subjects performed a Go No-Go task that required them to respond or inhibit responding based on threat or safety cues present in facial expressions. Subjects (N = 112) were divided into three age groups: adolescent (12-15 years), emerging adult (18-25 years) and adult (26-44 years). Analyses revealed a significant improvement in accuracy on No-Go trials, but not Go trials, during both safe and threat face conditions, with changes evident through early adulthood. In order to better identify the decision-making processes responsible for these changes in inhibitory control, a drift diffusion model (DDM) was fit to the accuracy and reaction time data, generating measures of caution, response bias, nondecision time (encoding + motor response), and drift rate (face processing efficiency). Caution and nondecision time both increased significantly with age while bias towards the Go response decreased. Drift rate analyses revealed significant age-related improvements in the ability to map threat faces to a No-Go response while drift rates on all other trial types were equivalent across age groups. These results suggest that both stimulus-independent and stimulus-dependent processes contribute to improvements in inhibitory control in adolescence with processing of negative social cues being specifically impaired by self-regulatory demands. Findings from this novel investigation of emotional responsiveness integrated with inhibitory control may provide useful insights about healthy development that can be applied to better understand adolescent risk-taking behavior and the elevated incidence of related forms of psychopathology during this period of life.

Nurses as patient navigators in cancer diagnosis: review, consultation and model design.

The diagnostic phase of cancer care is an anxious time for patients. Patient navigation is a way of assisting and supporting individuals during this time. The aim of this review is to explore patient navigation and its role in the diagnostic phase of cancer care. We reviewed the literature for definitions and models of navigation, preparation for the role and impact on patient outcomes, specifically addressing the role of the nurse in patient navigation. Interviews and focus groups with healthcare providers and managers provided further insight from these stakeholder groups. Common to most definitions of navigation is the navigator's multifaceted role in facilitating processes of care, assisting patients to overcome barriers and providing information and support. Navigation may be provided by laypersons, clerical staff and/or healthcare professionals. In the diagnostic phase it has the potential to affect efficiency of diagnostic testing, patients' experience during this time and preparation for decision-making around treatment options. Patient care during the diagnostic phase requires various levels of navigation, according to individual informational, physical and psychosocial needs. Identifying those individuals who require more support--whether physical or psychosocial--during the diagnostic phase is of critical importance.

The nature of increased hospital use in poor neighbourhoods: findings from a Canadian inner city.

The relationship between socioeconomic factors and hospital use is not well understood in the Canadian context. We used the 1991 Canada census and 1990-92 Ontario hospital discharge abstracts for residents of southeast Toronto to calculate crude and age-sex adjusted rates of hospital admission, bed days, and costs by quintile of low-income households. Population-based rates of admission to hospital, bed days and costs were all significantly related to census tract income (p < 0.01 for males and females). The number of admissions per person admitted was significantly associated with census tract income (p < 0.01 for males and females), but length of stay and resource intensity weight were not. Hospital costs were 50.0% higher for the poorest quintile of neighbourhoods than for the wealthiest and 35.8% higher than for the middle-income quintile. Poor urban neighbourhoods may require more resources than previously anticipated, related to higher hospital admission and readmission rates.

Current treatment options for the restoration of articular cartilage.

Over the past several decades, much has been learned about articular cartilage and its physiological capacity to restore itself. While articular cartilage does appear to have some regenerative capabilities, it appears to lose this capacity over a period of time, making restoration of articular surfaces more and more difficult. To date, no technique has been completely successful in achieving exactly normal regenerative articular cartilage. Arthroscopic lavage and debridement provides temporary relief of symptoms. This probably works by removing degradative enzymes that contribute to synovitis and also to the further breakdown of articular cartilage. Bone marrow stimulation techniques such as abrasion arthroplasty, drilling, and microfracture produce only fibrocartilage and therefore do not offer a long-term cure. Perichondral and periosteal interposition grafts produce repair tissue that is similar to hyaline cartilage but also lack the mechanical durability. Like bone marrow stimulation techniques, interposition grafts introduce precursor cells, which have a tendency to differentiate along lines other than cartilage. This leads to an inferior quality of repair tissue. Currently, chondrogenic-stimulating factors and artificial matrices are currently being researched and developed. Much has been learned about the various growth factors that stimulate chondrocyte differentiation and extracellular matrix production, but to date, there has not been a clinical technique that has shown any long-term promise. Ultimately, the goal will be to take precursor cells from an easily accessible source such as the iliac crest, mix them with growth factors that have been derived genetically in the lab, and provide an artificial matrix that in combination can produce restoration of articular cartilage at minimal cost and patient morbidity. Autologous osteochondral transplant systems have shown encouraging results but there are still problems. Graft matching and contouring to the recipient articular surface is difficult. Donor sites can be a limiting factor. Furthermore, the fibrocartilaginous interface between the donor and recipient site may contribute to breakdown in the long run. Autologous chondrocyte implantation is a biological repair process that also has shown encouraging results. It must be remembered that this is not normal articular cartilage--it is only hyaline-like cartilage. The technique is expensive and is technically difficult to perform. There are no randomized prospective studies that compare the natural history of the repair tissue to that of other forms of repair tissue. Long-term functional outcome is still a significant question mark. In addition, it has not been shown that autologous chondrocyte implantation can prevent degenerative changes. In the future, we probably will see delivery systems using stimulating growth factors, chondrocytes, and synthetically derived matrices. When placed in combination and with the right mechanical stimuli, we may ultimately achieve true restoration of articular cartilage.

A Potato Virus X Resistance Gene Mediates an Induced, Nonspecific Resistance in Protoplasts.

The Rx locus in potato controls extreme resistance to most isolates of potato virus X (PVX). The resistance is expressed in whole plants and in protoplasts. Rx-mediated resistance in protoplasts causes reduced accumulation of all PVX RNA species, including the (-) strand RNA after a lag of 8 hr postinoculation. In work reported elsewhere, we have shown that the Rx-breaking property of PVXHB was associated with the coat protein gene of PVXUK3 and PVXCP4. Here, we describe how a frameshift mutation in the coat protein gene had no effect on Rx resistance breaking but compromised the Rx-mediated resistance to PVXCP4. We also describe how in coinoculation experiments, the Rx-mediated resistance could be induced to affect PVXHB or cucumber mosaic virus (CMV). In these experiments, PVXHB or CMV was coinoculated to protoplasts (Rx genotype) together with an isolate of PVX, which is affected by Rx. We interpret this data to indicate that Rx-mediated resistance is induced when the PVX coat protein is produced in the infected cells and that the induced resistance mechanism is effective against viruses unrelated to PVX.

Pulmonary stenosis with ventricular septal defect, common aorticopulmonary trunk, and dextroposition of the aorta: morphologic and qualitative physiologic effects in caffeine-treated chick embryos.

Effects of caffeine administration to Hamburger-Hamilton stage 19 chick embryos (3 days of incubation) were investigated. A morphologic study of the effect of caffeine on cardiogenesis showed that caffeine produced total cardiac malformations in the chick in a dose-related fashion. A maximum frequency of 70.6% was observed with 4.7 mg caffeine. Major malformations included common aorticopulmonary trunk and dextroposition of the aorta accompanied by ventricular septal defect with/without pulmonary stenosis. Qualitative analysis of cinegraphs following exposure of embryos to a single teratogenic dose of caffeine (3.5 mg/egg) produced marked alterations in cardiac function when compared with chick Ringer's controls. Within 3 minutes after exposure to caffeine, dilation of the common ventricle and weak ventricular contractility were observed and persisted for 1 hour. Dose-response data and microcinematographic observations suggest that caffeine induced cardiac anomalies by a direct toxic effect on the embryo rather than by altering cardiac cell function. Our data also suggest that pathophysiologic changes in cardiac function may play an important role in the pathogenesis of caffeine-induced cardiac anomalies in the chick embryo.