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Delayed Return (delayed + return)
Selected AbstractsEffects of urethane anaesthesia on sensory processing in the rat barrel cortex revealed by combined optical imaging and electrophysiologyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2010Ian M. Devonshire Abstract The spatiotemporal dynamics of neuronal assemblies evoked by sensory stimuli have not yet been fully characterised, especially the extent to which they are modulated by prevailing brain states. In order to examine this issue, we induced different levels of anaesthesia, distinguished by specific electroencephalographic indices, and compared somatosensory-evoked potentials (SEPs) with voltage-sensitive dye imaging (VSDI) responses in the rat barrel cortex evoked by whisker deflection. At deeper levels of anaesthesia, all responses were reduced in amplitude but, surprisingly, only VSDI responses exhibited prolonged activation resulting in a delayed return to baseline. Further analysis of the optical signal demonstrated that the reduction in response amplitude was constant across the area of activation, resulting in a global down-scaling of the population response. The manner in which the optical signal relates to the various neuronal generators that produce the SEP signal is also discussed. These data provide information regarding the impact of anaesthetic agents on the brain, and show the value of combining spatial analyses from neuroimaging approaches with more traditional electrophysiological techniques. [source] Individual differences in the effects of chronic prazosin hydrochloride treatment on hippocampal mineralocorticoid and glucocorticoid receptorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2007Mohamed Kabbaj Abstract The aim of this study was to investigate the noradrenergic regulation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in high responder (HR) and low responder (LR) male rats, an animal model of individual differences in hypothalamo-pituitary-adrenal axis activity and vulnerability to drugs of abuse. The effects of a chronic treatment with the noradrenergic ,1 antagonist (1-[4-amino-6,7-dimethoxy-2-quinazolinyl]-4-[2-furanylcarbonyl] piperazine) hydrochloride (prazosin) (0.5 mg/kg, i.p., 35 days) were assessed on stress-induced corticosterone (CORT) secretion and on hippocampal MRs and GRs in adrenally intact rats. In order to ascertain whether the effects of chronic prazosin treatment on hippocampal MRs and GRs were direct or indirect, through prazosin-induced CORT secretion, we also assessed the effects of the same treatment on adrenalectomized rats with CORT substitutive therapy. When compared with LR rats, HR rats exhibited a delayed return to the basal level of CORT following acute restraint stress; this was associated with a lower binding of MRs and GRs in HR rats than in LR rats. Chronic prazosin treatment had no effect in HR animals but markedly reduced hippocampal MRs and GRs, and increased stress-induced CORT secretion in LR rats. In LR adrenalectomized rats, prazosin reduced hipppocampal MRs but did not change GRs. Our results provide evidence of a differential regulation by noradrenaline of hippocampal MRs and GRs in HR and LR rats. These data could have clinical implications in terms of individual differences in the resistance to antidepressant treatments and individual differences in drug abuse. [source] Hypothalamic-Pituitary-Adrenal Axis Abnormalities in Response to Deletion of 11,-HSD1 is Strain-DependentJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2009R. N. Carter Inter-individual differences in hypothalamic-pituitary-adrenal (HPA) axis activity underlie differential vulnerability to neuropsychiatric and metabolic disorders, although the basis of this variation is poorly understood. 11,-Hydroxysteroid dehydrogenase type 1 (11,-HSD1) has previously been shown to influence HPA axis activity. 129/MF1 mice null for 11,-HSD1 (129/MF1 HSD1,/,) have greatly increased adrenal gland size and altered HPA activity, consistent with reduced glucocorticoid negative feedback. On this background, concentrations of plasma corticosterone and adrenocorticotrophic hormone (ACTH) were elevated in unstressed mice, and showed a delayed return to baseline after stress in HSD1-null mice with reduced sensitivity to exogenous glucocorticoid feedback compared to same-background genetic controls. In the present study, we report that the genetic background can dramatically alter this pattern. By contrast to HSD1,/, mice on a 129/MF1 background, HSD1,/, mice congenic on a C57Bl/6J background have normal basal plasma corticosterone and ACTH concentrations and exhibit normal return to baseline of plasma corticosterone and ACTH concentrations after stress. Furthermore, in contrast to 129/MF1 HSD1,/, mice, C57Bl/6J HSD1,/, mice have increased glucocorticoid receptor expression in areas of the brain involved in glucocorticoid negative feedback (hippocampus and paraventricular nucleus), suggesting this may be a compensatory response to normalise feedback control of the HPA axis. In support of this hypothesis, C57Bl/6J HSD1,/, mice show increased sensitivity to dexamethasone-mediated suppression of peak corticosterone. Thus, although 11,-HSD1 appears to contribute to regulation of the HPA axis, the genetic background is crucial in governing the response to (and hence the consequences of) its loss. Similar variations in plasticity may underpin inter-individual differences in vulnerability to disorders associated with HPA axis dysregulation. They also indicate that 11,-HSD1 inhibition does not inevitably activate the HPA axis. [source] Sequential Plasma Lactate Concentrations as Prognostic Indicators in Adult Equine EmergenciesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2010B.S. Tennent-Brown Background: Sequential lactate concentration ([LAC]) measurements have prognostic value in that hospitalized humans and neonatal foals that have a delayed return to normolactatemia have greater morbidity and case fatality rate. Hypothesis: Prognosis for survival is decreased in horses with a delayed return to normal [LAC]. Animals: Two hundred and fifty adult horses presented for emergency evaluation excepting horses evaluated because of only ophthalmologic conditions, superficial wounds, and septic synovitis without systemic involvement. Methods: Prospective observational study. [LAC] was measured at admission and then at 6, 12, 24, 48, and 72 hours after admission. The change in [LAC] over time ([LAC],T) was calculated from changes in [LAC] between sampling points. Results: Median [LAC] was significantly (P < .001) higher at admission in nonsurvivors (4.10 mmol/L [range, 0.60,18.20 mmol/L]) when compared with survivors (1.30 mmol/L [range, 0.30,13.90 mmol/L]) and this difference remained at all subsequent time points. The odds ratio for nonsurvival increased from 1.29 (95% confidence interval 1.17,1.43) at admission to 49.90 (6.47,384) at 72 hours after admission for every 1 mmol/L increase in [LAC]. [LAC],T was initially positive in all horses but became negative and significantly lower in nonsurvivors for the time periods between 24,72 hours (, 0.47, P= .001) and 48,72 hours (, 0.07, P= .032) when compared with survivors (0.00 at both time periods) consistent with lactate accumulation in nonsurvivors. Conclusions and Clinical Importance: These results indicate that lactate metabolism is impaired in critically ill horses and [LAC],T can be a useful prognostic indicator in horses. [source] Assessment of the patency of microvascular anastomoses using microscope-integrated near-infrared angiography: A preliminary studyMICROSURGERY, Issue 7 2009Charlotte Holm M.D., Ph.D. Background: Technical problems at the site of the anastomosis compromise an underappreciated proportion of microsurgical free tissue transfers. Intraoperative identification of technical errors may be able to prevent reexploration surgery and early flap failure. We report the first human study on a new microscope-integrated fluorescence angiography technique, which allows for intraoperative imaging of the anastomotic site. Methods: Fifty consecutive patients undergoing reconstructive microsurgical procedures were enrolled in the study. Intraoperative near infrared indocyanine green videoangiography (ICGA) was performed on all microsurgical anastomoses, after they had been assessed by the operating surgeon by conventional clinical patency tests. Anastomoses deemed to be occluded by the ICG-angiography were intraoperatively revised, and the result of revision was compared with angiographic findings. Results: In 11/50 (22%) of patients, where the surgeon had classified the anastomoses as patent, microangiography identified a total luminal occlusion (six) and/or significant alterations in blood flow (five), potentially predisposing toward postoperative flap failure. Intraoperative revision confirmed angiographic findings in 100% of cases, and was always associated with flap survival. The decision not to revise despite anastomotic occlusion by the intraoperative angiogram was always followed by flap loss or early reexploration. A delayed return of venous blood from the flap predisposed toward postoperative flap failure. Conclusions: Hand-sewn anastomoses are subject to technical errors, and conventional patency tests have a low sensitivity for revealing anastomotic failure. Microscope integrated microangiography is an excellent method for identifying significant anastomotic problems, which would have otherwise gone unnoticed. The potential impact on early flap failure and reexploration surgery is considerable. © 2009 Wiley-Liss, Inc. Microsurgery 2009. [source] Predictors of delayed return to work after back injury: A case,control analysis of union carpenters in Washington StateAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 11 2009Kristen L. Kucera PhD Abstract Methods Union administrative records identified 20,642 union carpenters who worked in Washington State from 1989 to 2003. The Department of Labor and Industries provided records of workers' compensation claims and associated medical care. Work-related back claims (n,=,4,241) were identified by ANSI codes (back, trunk, or neck/back) or ICD-9 codes relevant to medical care consistent with a back injury. Cases (n,=,738) were defined as back injury claims with >90 days of paid lost time; controls (n,=,699) resulted in return to work within 30 days. Logistic regression models estimated odds ratios and 95% confidence intervals (OR, 95% CI) of delayed return to work (DRTW). Results Thirty percent of case claims and 8% of control claims were identified by an ICD-9 code. DRTW after back injury was associated with being female (2.7, 95% CI: 1.3,5.5), age 30,44 (1.2, 95% CI: 0.9,1.7) and age over 45 (1.6, 95% CI: 1.1,2.3), four or more years union experience (1.4, 95% CI: 1.1,1.8), previous paid time loss back claim (1.8, 95% CI: 1.3,2.5), and ,30-day delay to medical care (3.6, 95% CI: 2.1, 6.1). Evidence of more acute trauma was also associated with DRTW. Conclusions Use of ICD-9 codes identified claims with multiple injuries that would otherwise not be captured by ANSI codes alone. Though carpenters of younger age and inexperience were at increased risk for a paid lost time back injury claim, older carpenters and more experienced workers, once injured, were more likely to have DRTW as were those who experienced acute events. Am. J. Ind. Med. 52:821,830, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||