The abbreviated vigilance task and cerebral hemodynamics

Transcranial Doppler sonography (TCD) and transcranial cerebral oximetry (TCCO) measures of cerebral blood flow velocity and oxygenation levels were collected during an abbreviated 12-min vigilance task. Both the TCD and TCCO measures showed higher levels of cerebral vascular activity in the right than in the left cerebral hemisphere; the cerebral laterality of vigilance occurs in an abbreviated task. Although there was a significant decline in performance over time, there was no significant change in the physiological measures over time during the abbreviated vigil. This latter finding does not match the physiological changes detected in long-duration vigils.     

Impulsive responding and the sustained attention to response task

Two studies investigated whether the sustained attention to response task (SART) is a better measure of impulsive responding than of sustained attention. Participants performed target detection tasks with global-local letter stimuli using one of two response formats: standard, responding to targets; and SART, withholding to targets. In the first experiment, performance in the SART changed rapidly over time, whereas performance in the standard format was stable over time. In the second experiment, performance in the SART was susceptible to global-local condensation tasks, a result previously found with highly impulsive individuals. Overall the results indicate that the SART is sensitive to impulsive responding.     

Contemporary issues in dental education in Australia

Australia has witnessed a proliferation of dental workforce training opportunities over the last 15 years, including dentists, dental therapists, dental hygienists and prosthetists. The reasons for this have not been examined critically. Universities have welcomed the opportunities to increase the student base but do not seem to have examined the advisability of continued expansion or its impact on the delivery and costs of health services. Nor have they enquired expressly whether they have any responsibility in these matters. Public health benefits should constitute a significant element of curriculum design. There seems to have been a general acceptance of the premise that more is necessarily better. Ironically, these developments have occurred in the face of significant recurrent cost increments and serious academic staff shortages. The schools have responded with alterations to curriculum content. Student cohort composition, course structures, educational focus, postgraduate training and research have been affected. The primary purpose of this review is to highlight the issues which currently drive workforce training and curriculum content and to suggest that some current practices should be re-examined as a starting point for setting defined common objectives within the Australian dental educational spectrum. Salient issues which require examination include course standards and accreditation, workforce mix, dental health demands, public service obligations and staffing profiles.     

Design of the Balance@Work project: systematic development, evaluation and implementation of an occupational health guideline aimed at the prevention of weight gain among employees

Background  

Occupational health professionals may play an important role in preventive health promotion activities for employees. However, due to a lack of knowledge and evidence- and practice based methods and strategies, interventions are hardly being implemented by occupational physicians to date. The aim of the Balance@Work project is to develop, evaluate, and implement an occupational health guideline aimed at the prevention of weight gain among employees.     

Is DARPP-32 a potential therapeutic target?

Signaling pathways play important roles in the coordination and integration of a myriad cellular functions. Because of widespread interest in the dopaminergic pathways, the protein dopamine and cyclic adenosine 3',5'-monophosphate-regulated phosphoprotein with molecular weight of 32 kDa, known by the acronym DARPP-32, occupies a central role in the biology of dopaminoceptive neurons in the central and peripheral nervous system (PNS). Its involvement has been demonstrated in many neural phenomena, including physiologic and pathologic neuroplasticity to drug effects and cognition. However, DARPP-32 has also been identified in non-neuronal tissues and its level of expression has been associated with the malignant level of some types of cancer, via modulation of cell survival and differentiation. This review considers some of these apparently compartmentalized functions of DARPP-32 and its potential as a therapeutic target.     

A phase II study of the farnesyl transferase inhibitor, tipifarnib, in children with recurrent or progressive high-grade glioma, medulloblastoma/primitive neuroectodermal tumor, or brainstem glioma: a Children's Oncology Group study

BACKGROUND: An open-label Phase II study of tipifarnib was conducted to evaluate its safety and efficacy in children with recurrent or refractory medulloblastoma (MB)/primitive neuroectodermal tumor (PNET), high-grade glioma (HGG), and diffuse intrinsic brainstem glioma (BSG). METHODS: Between January 2004 and July 2005, patients were enrolled and stratified as follows: Stratum 1, recurrent or refractory MB/PNET; Stratum 2, recurrent or refractory HGG; and Stratum 3, recurrent or refractory BSG. Patients received tipifarnib 200 mg/m2 per dose twice daily for 21 days repeated every 28 days. Patients who received enzyme-inducing anticonvulsants and other CYP3A4/5 inducers or inhibitors were excluded. The primary objective was to estimate the sustained response rate in all strata. RESULTS: Ninety-seven patients with a median age of 11.2 years (range, 3.2-21.9 years) were enrolled on the study, and 81 patients were evaluable for response. One of 35 patients with BSG and 1 of 31 patients with HGG had a sustained partial response. No responses were observed in 15 patients with MB/PNET. Eight patients (3 HGG, 1 MB, and 4 BSG) remained stable for >or=4 courses (range, 4-25 courses). The median number of courses received was 2 (range, 1-25 courses). The most frequent grade 3 and 4 toxicities included neutropenia (18.7%), thrombocytopenia (14.3%), and leukopenia (14.3%). The 6-month progression-free survival rate (+/-standard deviation) was 14%+/-6% for HGG, 6%+/-6% for MB/PNET and 3%+/-3% for BSG. CONCLUSIONS: Tipifarnib tolerated well but had little activity as a single agent in children with recurrent central nervous system malignancies.     

Visual identification of bacterially contaminated red cells

There have been increasing numbers of reports of transfusion-acquired Yersinia enterocolitica bacteremia (including several fatal cases). Fifteen units of whole blood were inoculated with various concentrations of Y. enterocolitica serotype 0:3 and processed into AS-3 preserved red cells (RBCs). Consistent growth of the organism was found at inoculum concentrations greater than or equal to 10 colony-forming units per mL. In all 13 units of RBCs that supported the growth of Y. enterocolitica, a darkening in color (due to hemolysis and a decrease in pO2) was observed in the bag. The attached sample segments, which were sealed from the main unit, remained sterile and did not darken. This color change was apparent in all the contaminated units by Day 35, which was 1.5 to 2 weeks after the bacteria were first detected in cultures of the blood. Hence, by comparison of the color of the segment tubing with that of the unit itself, units grossly contaminated with Y. enterocolitica can be identified prior to transfusion. Moreover, review of photographs on file at the Centers for Disease Control revealed this dramatic color change in 2 units of blood that caused transfusion-transmitted sepsis (Enterobacter agglomerans and an unidentified gram-negative bacillus, not Yersinia sp.), which demonstrated that the color change was not limited to Y. enterocolitica. This method of visual identification of contaminated units of blood could decrease the incidence of posttransfusion bacterial sepsis.     

Effects of cholinergic modulation on responses of neocortical neurons to fluctuating input

Neocortical neurons in vivo are spontaneously active and intracellular recordings have revealed strongly fluctuating membrane potentials arising from the irregular arrival of excitatory and inhibitory synaptic potentials. In addition to these rapid fluctuations, more slowly varying influences from diffuse activation of neuromodulatory systems alter the excitability of cortical neurons by modulating a variety of potassium conductances. In particular, acetylcholine, which effects learning and memory, reduces the slow alterhyperpolarization, which contributes to spike frequency adaptation. We used whole-cell patch-clamp recordings of pyramidal neurons in neocortical slices and computational simulations to show, first, that when fluctuating inputs were added to a constant current pulse, spike frequency adaptation was reduced as the amplitude of the fluctuations was increased. High- frequency, high-amplitude fluctuating inputs that resembled in vivo conditions exhibited only weak spike frequency adaptation. Second, bath application of carbachol, a cholinergic agonist, significantly increased the firing rate in response to a fluctuating input but minimally displaced the spike times by < 3 ms, comparable to the spike jitter observed when a visual stimulus is repeated under in vivo conditions. These results suggest that cholinergic modulation may preserve information encoded in precise spike timing, but not in interspike intervals, and that cholinergic mechanisms other than those involving adaptation may contribute significantly to cholinergic modulation of learning and memory.      

Alterations of In-vitro 5-HT Receptor Pharmacology as a Function of Multiple Treatment with 5-Hydroxytryptamine or 8-Hydroxy-2-(di-N-propylamino) Tetralin in Rat Isolated Aorta,Uterus and Fundus,and Guinea-pig Isolated Trachea

Abstract— The effects of single and multiple (5, 10, or 15 days) administration of the 5-HT_1A agonist 8-hydroxy-2-(di-N-propylamino) tetralin (8-OH-DPAT) (3 mg kg^?1, i.p.) or 5-HT (3 mg kg^?1, i.p.) in-vivo on the response of selected isolated smooth muscles to 5-HT in-vitro were investigated. Single dosing with 8-OH-DPAT did not alter the responses of the isolated tissues (rat aorta, uterus or fundus, or guinea-pig trachea) to 5-HT, while multiple dosing with 8-OH-DPAT produced rightward shifts and a suppression of the maximum response of all these tissues to 5-HT, with the exception of the rat stomach fundus. Multiple administration of 5-HT had no effect on the in-vitro response of the tissues to 5-HT. These data indicate that multiple administration of 8-OH-DPAT desensitizes or down-regulates the peripheral 5-HT₂ receptors found on the rat aorta and uterus, and guinea-pig trachea.