Functional analysis and treatment of problem behavior exhibited by elementary school children.
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A functional analysis involving antecedent events was conducted with 4 students who had been identified as having behavior problems. Off-task behavior was measured while task difficulty and level of adult attention were manipulated during analogue sessions. Results revealed two patterns: Three students displayed higher rates of off-task behavior during difficult tasks, and 1 displayed higher rates of off-task behavior during sessions with low attention. Improved behavior was observed when students were taught an alternative behavior that matched the assessment results. (+info)
Hindlimb locomotor and postural training modulates glycinergic inhibition in the spinal cord of the adult spinal cat.
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Adult spinal cats were trained initially to perform either bipedal hindlimb locomotion on a treadmill or full-weight-bearing hindlimb standing. After 12 wk of training, stepping ability was tested before and after the administration (intraperitoneal) of the glycinergic receptor antagonist, strychnine. Spinal cats that were trained to stand after spinalization had poor locomotor ability as reported previously, but strychnine administration induced full-weight-bearing stepping in their hindlimbs within 30-45 min. In the cats that were trained to step after spinalization, full-weight-bearing stepping occurred and was unaffected by strychnine. Each cat then was retrained to perform the other task for 12 wk and locomotor ability was retested. The spinal cats that were trained initially to stand recovered the ability to step after they received 12 wk of treadmill training and strychnine was no longer effective in facilitating their locomotion. Locomotor ability declined in the spinal cats that were retrained to stand and strychnine restored the ability to step to the levels that were acquired after the step-training period. Based on analyses of hindlimb muscle electromyographic activity patterns and kinematic characteristics, strychnine improved the consistency of the stepping and enhanced the execution of hindlimb flexion during full-weight-bearing step cycles in the spinal cats when they were trained to stand but not when they were trained to step. The present findings provide evidence that 1) the neural circuits that generate full-weight-bearing hindlimb stepping are present in the spinal cord of chronic spinal cats that can and cannot step; however, the ability of these circuits to interpret sensory input to drive stepping is mediated at least in part by glycinergic inhibition; and 2) these spinal circuits adapt to the specific motor task imposed, and that these adaptations may include modifications in the glycinergic pathways that provide inhibition. (+info)
GT1-1 cells exhibit spontaneous action potentials and transient increases in intracellular calcium concentration ([Ca2+]i) that occur in individual cells and as spatially propagated intercellular Ca2+ waves. In this study, simultaneous cell-attached patch-clamp recording of action currents (indicative of action potentials) and fluorescence imaging of [Ca2+]i revealed that Ca2+ transients in GT1-1 cells were preceded by a single action current or a burst of action currents. Action currents preceded Ca2+ transients in a similar pattern regardless of whether the Ca2+ transients were limited to the individual cell or occurred as part of an intercellular Ca2+ wave. Both the action currents and Ca2+ transients were abolished by 1 microM tetrodotoxin. Removal of extracellular Ca2+ abolished all spontaneous Ca2+ transients without inhibiting the firing of action currents. Nimodipine, which blocks L-type Ca2+ currents in GT1-1 cells, also abolished all spontaneous Ca2+ signaling. Delivery of small voltage steps to the patch pipette in the cell-attached configuration elicited action currents the latency to firing of which decreased with increasing amplitude of the voltage step. These results indicate that spontaneous intercellular Ca2+ waves are generated by a propagated depolarization, the firing of action potentials in individual cells, and the resulting influx of Ca2+ through L-type Ca2+ channels. These patterns of spontaneous activity may be important in driving the pulsatile release of GnRH from networks of cells. (+info)
Voice-controlled robotic arm in laparoscopic surgery.
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AIM: To report on our experience with a voice-directed robotic arm for scope management in different procedures for "solo-surgery" and in complex laparoscopic operations. METHODS: A chip card with orders for the robotic arm is individually manufactured for every user. A surgeon gives order through a microphone and the optic field is thus under direct command of the surgeon. RESULTS: We analyzed 200 cases of laparoscopic procedures (gallbladder, stomach, colon, and hernia repair) done with the robotic arm. In each procedure the robotic arm worked precisely; voice understanding was exact and functioned flawlessly. A hundred "solo-surgery" operations were performed by a single surgeon. Another 96 complex videoscopic procedures were performed by a surgeon and one assistant. In comparison to other surgical procedures, operative time was not prolonged, and the number of used ports remained unchanged. CONCLUSION: Using the robotic arm in some procedures abolishes the need for assist ance. Further benefit accrued by the use of robotic assistance includes greater stability of view, less inadvertent smearing of the lens, and the absence of fatigue. The robotic arm can be used successfully in every operating theater by all surgeons using laparoscopy. (+info)
The hospital library online--a point of service for consumers and hospital staff: a case study.
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The Health Library at Stanford University is described in the context of electronic information services provided to Stanford University Medical Center, the local community, and Internet users in general. The evolution from CD-ROM-based services to Web-based services and in-library services to networked resources are described. Electronic services have expanded the mission of The Health Library to include national and international users and the provision of unique services and collections. (+info)
Somatic amplification of distally generated subthreshold EPSPs in rat hippocampal pyramidal neurones.
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1. Intracellular recordings from hippocampal CA1 pyramidal neurones revealed that EPSPs evoked by selective stimulation of the isolated afferent input to the distal third of the apical dendrites were relatively insensitive to changes in dendritic membrane potential (Vm) but amplified by depolarizations of the somatic Vm. The amplification was present at potentials depolarized from resting membrane potential (RMP) but was most marked when the EPSPs were close to threshold for action potential generation. The amplification consisted of a uniform component and a variable component which was only present when the EPSPs were threshold straddling. 2. The somatic amplification was caused by an intrinsic membrane current which was blocked by somatic application of tetrodotoxin (TTX, 10 microM), but was insensitive to bath application of NiCl2 (100-200 microM). We therefore suggest that the amplification of the subthreshold EPSP is due primarily to the activation of a non-inactivating Na+ current (INaP). 3. Injection of 4-aminopyridine (4-AP, 25-50 mM) during intradendritic recordings resulted in amplification of the EPSPs in 37% of the dendrites, which was similar to that observed in somatic recordings. However, in the one case in which somatic application of TTX was tested, dendritic amplification was blocked, suggesting that it is a reflection of the somatic amplification. 4. Because the shift to variable amplification was very abrupt and it is present in only a very narrow voltage range close to threshold, we suggest that the variable component is caused by the regenerative activation of INaP. The variability itself is probably due to the simultaneous activation of different outward K+ currents. 5. The present results indicate that the somatic region of CA1 pyramidal neurones can function as a voltage-dependent amplifier of distally evoked EPSPs and that this is due to the activation of a somatic INaP. The presence of this amplifying mechanism will have important functional consequences for the way in which distally generated EPSPs are integrated. (+info)
Endothelin and mechanical properties of the carotid artery in Wistar-Kyoto and spontaneously hypertensive rats.
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The aim of this study is to evaluate the role of endothelin in the control of the static mechanical properties of in vitro carotid arteries from 14-week-old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). An in vitro preparation in which the artery was allowed to longitudinally elongate similarly to the in situ carotid artery was employed. The diameter of in vitro carotid arteries subjected to static pressures (from 25 to 200 mmHg in 25 mmHg steps) was determined by videomicroscopy and computer-assisted image analysis, the cross-sectional compliance- and distensibility-pressure curves being then derived. The role of endothelin was assessed by incubating carotid arteries with the selective ETA and ETB endothelin receptor antagonists BQ123 and BQ788, respectively. These effects were compared with those observed under control conditions, as well as with those following complete abolition of vascular smooth muscle tone by potassium cyanide (KCN). Carotid diameter was significantly larger, and compliance and distensibility significantly smaller, in SHR compared to WKY rats. Local incubation with BQ123 was associated with significant dilations as well as significant increases in cross-sectional compliance and distensibility in both strains. This was even more pronounced with KCN, while BQ788 had no effect. The results of the present study suggest that: (i) endothelin exerts a tonic stiffening effect on the in vitro common carotid artery; (ii) this effect is mediated via the ETA endothelin receptor, and (iii) the stiffening effect of endothelin is exerted to a similar extent in the carotid arteries of normotensive WKY and SHR rats. (+info)
ATP-Induced Ca(2+) release in cochlear outer hair cells: localization of an inositol triphosphate-gated Ca(2+) store to the base of the sensory hair bundle.
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We used a high-performance fluorescence imaging system to visualize rapid changes in intracellular free Ca(2+) concentration ([Ca(2+)](i)) evoked by focal applications of extracellular ATP to the hair bundle of outer hair cells (OHCs): the sensory-motor receptors of the cochlea. Simultaneous recordings of the whole-cell current and Calcium Green-1 fluorescence showed a two-component increase in [Ca(2+)](i). After an initial entry of Ca(2+) through the apical membrane, a second and larger, inositol triphosphate (InsP(3))-gated, [Ca(2+)](i) surge occurred at the base of the hair bundle. Electron microscopy of this intracellular Ca(2+) release site showed that it coincides with the localization of a unique system of endoplasmic reticulum (ER) membranes and mitochondria known as Hensen's body. Using confocal immunofluorescence microscopy, we showed that InsP(3) receptors share this location. Consistent with a Ca(2+)-mobilizing second messenger system linked to ATP-P2 receptors, we also determined that an isoform of G-proteins is present in the stereocilia. Voltage-driven cell shape changes and nonlinear capacitance were monitored before and after ATP application, showing that the ATP-evoked [Ca(2+)](i) rise did not interfere with the OHC electromotility mechanism. This second messenger signaling mechanism bypasses the Ca(2+)-clearance power of the stereocilia and transiently elevates [Ca(2+)](i) at the base of the hair bundle, where it can potentially modulate the action of unconventional myosin isozymes involved in maintaining the hair bundle integrity and potentially influence mechanotransduction. (+info)