Georgetown University

About: Georgetown University is a education organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 23377 authors who have published 43718 publications receiving 1748598 citations. The organization is also known as: GU & Georgetown.

Impression Management in the Feedback-Seeking Process: A Literature Review and Research Agenda

Abstract: Although impression management in the Feedback-seeking process has emerged as an important research topic, existing research has failed to capture the range and complexity of impression management behaviors. This article provides a theoretical framework for existing and future research. It examines how impression management sometimes discourages and at other times encourages feedback inquiry, and it explains the impact that impression management has on when, from whom, and how individuals ask for feedback. Organizational implications of the impression management motive in feedback seeking are discussed.

Validity of Adolescent Self-Report of Alcohol and Other Drug Involvement

Abstract: Validity of adolescent self-report of alcohol and drug use and consequential effects and problems is examined. Validity is discussed in terms of its importance in research and clinical work. Also, results from a recent study are presented that focus on self-report temporal stability and response bias tendencies as evidence of validity of self-report. Study results indicate that the great majority of drug clinic and school teenagers gave temporally consistent reports of substance involvement and that only a small proportion of drug clinic and school subjects presented extreme response bias tendencies. [Translations are provided in the International Abstracts section of this issue.]

The time course of epidermal nerve fibre regeneration: studies in normal controls and in people with diabetes, with and without neuropathy.

Abstract: Summary We sought to develop and validate a standardized cutaneous nerve regeneration model and to define the rate of epidermal nerve fibre (ENF) regeneration first in healthy control subjects and then in neuropathic and neuropathy-free subjects with diabetes. Next, we assessed the effect of different factors on the rate of nerve fibre regeneration and investigated whether such an approach might offer insight into novel trial designs and outcome measures. All subjects had a standardized topical capsaicin dressing applied to the distal lateral thigh. ENF densities derived from skin biopsies were determined at baseline, after capsaicin treatment and at reinnervation time points. For each subject, the best fit line from post-denervation data was determined and the slope was used as the rate of regeneration. In healthy control subjects, regeneration was correlated with psychophysical sensory testing, electron microscopy studies and immunohistochemistry with alternative axonal membrane markers. Topical capsaicin application produced complete or nearly complete denervation of the epidermis in both control subjects and people with diabetes. The rate of regeneration was associated with the baseline ENF density (P < 0.001), but not age (P = 0.75), gender (P = 0.18), epidermal thickness (P = 0.4) or post-capsaicin treatment density (P = 0.7). ENF regeneration, as determined by recovery of ENF density, occurred at a rate of 0.177 6 0.075 fibres/mm/ day in healthy control subjects and was significantly reduced in subjects with diabetes (0.074 6 0.064, P < 0.001) after adjusting for changes in baseline ENF density. Among subjects with diabetes, the presence of neuropathy was associated with a further reduction in regenerative rate (0.10 6 0.07 versus 0.04 6 0.03, P = 0.03), though diabetes type (P = 0.7), duration of diabetes (P = 0.3) or baseline glycated haemoglobin (P = 0.6) were not significant. These results have several implications. First, topical capsaicin application can produce a uniform epidermal nerve fibre injury that is safe and well tolerated, and offers an efficient strategy to measure and study nerve regeneration in man. Secondly, using our techniques, reduced rates of nerve regeneration were found in people with diabetes without evidence of neuropathy and indicate that abnormalities in peripheral nerve function are present early in diabetes, before signs or symptoms develop. These results suggest that regenerative neuropathy trials could include non-neuropathic subjects and that trial duration can be dramatically shortened.

Erythropoietin receptor signalling is required for normal brain development

Abstract: Erythropoietin, known for its role in erythroid differentiation, has been shown to be neuroprotective during brain ischaemia in adult animal models. Although high levels of erythropoietin receptor are produced in embryonic brain, the role of erythropoietin during brain development is uncertain. We now provide evidence that erythropoietin acts to stimulate neural progenitor cells and to prevent apoptosis in the embryonic brain. Mice lacking the erythropoietin receptor exhibit severe anaemia and defective cardiac development, and die at embryonic day 13.5 (E13.5). By E12.5, in addition to apoptosis in foetal liver, endocardium and myocardium, the erythropoietin receptor null mouse shows extensive apoptosis in foetal brain. Lack of erythropoietin receptor affects brain development as early as E10.5, resulting in a reduction in the number of neural progenitor cells and increased apoptosis. Corresponding in vitro cultures of cortical cells from Epor –/– mice also exhibited decreases in neuron generation compared with normal controls and increased sensitivity to low oxygen tension with no surviving neurons in Epor –/– cortical cultures after 24 hour exposure to hypoxia. The viability of primary Epor +/+ rodent embryonic cortical neurons was further increased by erythropoietin stimulation. Exposure of these cultures to hypoxia induced erythropoietin expression and a tenfold increase in erythropoietin receptor expression, increased cell survival and decreased apoptosis. Cultures of neuronal progenitor cells also exhibited a proliferative response to erythropoietin stimulation. These data demonstrate that the neuroprotective activity of erythropoietin is observed as early as E10.5 in the developing brain, and that induction of erythropoietin and its receptor by hypoxia may contribute to selective cell survival in the brain.