High-frequency submaximal stimulation over muscle evokes centrally generated forces in human upper limb skeletal muscles.

Control of posture and movement requires control of the output from motoneurons. Motoneurons of human lower limb muscles exhibit sustained, submaximal activity to high-frequency electrical trains, which has been hypothesized to be partly triggered by monosynaptic Ia afferents. The possibility to trigger such behavior in upper limb motoneurons and the potential unique role of Ia afferents to trigger such behavior remain unclear.

Forces consistent with plateau-like behaviour of spinal neurons evoked in patients with spinal cord injuries.

Percutaneous electrical stimulation over tibialis anterior and triceps surae was performed in 14 patients with traumatic spinal cord injury (SCI) to look for evidence that 'extra contractions' can develop, beyond those due to activation of the motor axons beneath the stimulating electrodes. Criteria for the extra contractions included marked asymmetry of force with respect to stimulation, progressively rising force during stimulation of constant amplitude and frequency, and force remaining high after stimulation frequency had returned to the control level following a high-frequency burst. Twelve of the 14 patients showed evidence of such behaviour, more frequently in triceps surae than tibialis anterior.

Suppression of human anti-inflammatory plasma cytokines IL-10 and IL-1RA with elevation of proinflammatory cytokine IFN-gamma during the isolation of the Antarctic winter.

Cellular immune function has been shown to be decreased and latent virus shedding to be increased in human beings isolated during the Antarctic winter, a model used for assessing some effects of space flight. However, the balance of proinflammatory (IFN-gamma) and anti-inflammatory (IL-10 and IL-1RA) cytokines has not previously been evaluated. We therefore sought to determine whether isolation during the Antarctic winter would alter the proinflammatory and anti-inflammatory cytokine balance.

Antibody responses to bacteriophage phi X-174 in human subjects exposed to the antarctic winter-over model of spaceflight.

Background: It has been proposed that exposure to long-term spaceflight conditions (stress, isolation, sleep disruption, containment, microbial contamination, and solar radiation) or to ground-based models of spaceflight will alter human immune responses, but specific antibody responses have not been fully evaluated.

Objective: We sought to determine whether exposure to the 8-month Antarctic winter-over model of spaceflight would alter human antibody responses.

Methods: During the 1999 Australian National Antarctic Research Expeditions, 11 adult study subjects at Casey, Antarctica, and 7 control subjects at Macquarie Island, sub-Antarctica, received primary and secondary immunizations with the T cell-dependent neoantigen bacteriophage phi X-174.

Implantable cardioverter defibrillator electrogram recognition with a multilayer perceptron.

With the continuing development of new pacing and shock modalities, implantable cardioverter defibrillators must be able to recognize an increasingly wider range of arrhythmias so that therapy is delivered in an optimal way. Current rate-based systems can no longer meet this need. It is, therefore, necessary to develop new techniques that consider waveform morphology in addition to heart rate.