Philosophical transactions of the Royal Society of London. Series B, Biological sciences
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Philos. Trans. R. Soc. Lond., B, Biol. Sci. · Mar 1996
ReviewPhenotypic modification of primary sensory neurons: the role of nerve growth factor in the production of persistent pain.
Inflammation results in an early and maintained elevation in nerve growth factor (NGF) levels in inflamed tissues. Neutralizing the action of the increased NGF with specific anti-NGF antibodies substantially diminishes inflammatory hypersensitivity, indicating that this neurotrophin is a key mediator in the production of inflammatory pain. ⋯ This chapter reviews evidence suggesting that an NGF-mediated modification of gene expression in the dorsal root ganglion during inflammation is central to the pathophysiology of persistent pain. The phenotype changes produced by NGF during inflammation include elevation of neuropeptides which may amplify sensory input signals in the spinal cord and augment neurogenic inflammation in the periphery and the upregulation of growth related molecules which may lead to a hyperinnervation of injured tissue by promoting terminal sprouting.
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Philos. Trans. R. Soc. Lond., B, Biol. Sci. · Aug 1995
Proprioceptive hair cells on the neck of the squid Lolliguncula brevis: a sense organ in cephalopods for the control of head-to-body position.
Decapod cephalopods, such as cuttlefishes and squids, have a distinct neck region that allows movements (roll, pitch and yaw) of the head relative to the body. This paper describes the structure, innervation and central pathways of proprioceptive hair cells on the neck of the squid Lolliguncula brevis that sense such movements and control head-to-body position. These hair cells exist on the dorsal side of the neck underneath the nuchal cartilage, close to the animal's midline on either side of the nuchal crest. ⋯ Bilateral deafferentation of the cells elicited a downward head pitch offset. This offset was superimposed on the compensatory head pitch response during imposed body pitch. These morphological and behavioural findings show that the neck hair cells and the associated nuchal cartilage structures of Lolliguncula brevis form a neck receptor organ that, together with statocyst and visual inputs, controls the position of the animal's head and body.
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Philos. Trans. R. Soc. Lond., B, Biol. Sci. · Jul 1991
The long-term effectiveness of different regimens of occlusion on recovery from early monocular deprivation in kittens.
Although the behavioural effects of an early period of monocular deprivation imposed on kittens can be very severe, resembling an extreme form of the human clinical condition deprivation amblyopia, they are not necessarily irreversible. Considerable behavioural as well as physiological recovery can occur if normal visual input is restored to the deprived eye sufficiently early, particularly if the other (initially non-deprived) eye is occluded at the same time (reverse occlusion). However, past work has shown that in many situations the improvement in the vision of the initially deprived eye that occurs during reverse occlusion is not retained following the subsequent introduction of binocular visual input. ⋯ Experiments were done to establish some of the factors that contributed to the successful outcome associated with certain of the regimens of part-time reverse occlusion. It was established that recovery was just as good in animals in which the visual axes were vertically misaligned by means of prisms during the daily period of binocular visual exposure, thereby indicating that the visual input to the two eyes need not be concordant. However, animals that received equivalent visual exposure of the two eyes each day, but successively rather than simultaneously, all developed very severe bilateral amblyopia.(ABSTRACT TRUNCATED AT 400 WORDS)
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Philos. Trans. R. Soc. Lond., B, Biol. Sci. · Apr 1990
The contribution of latent human failures to the breakdown of complex systems.
Several recent accidents in complex high-risk technologies had their primary origins in a variety of delayed-action human failures committed long before an emergency state could be recognized. These disasters were due to the adverse conjunction of a large number of causal factors, each one necessary but singly insufficient to achieve the catastrophic outcome. Although the errors and violations of those at the immediate human-system interface often feature large in the post-accident investigations, it is evident that these 'front-line' operators are rarely the principal instigators of system breakdown. ⋯ New methods of risk assessment and risk management are needed if we are to achieve any significant improvements in the safety of complex, well-defended, socio-technical systems. This paper distinguishes between active and latent human failures and proposes a general framework for understanding the dynamics of accident causation. It also suggests ways in which current methods of protection may be enhanced, and concludes by discussing the unusual structural features of 'high-reliability' organizations.
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Philos. Trans. R. Soc. Lond., B, Biol. Sci. · Feb 1985
Visceral nociception: peripheral and central aspects of visceral nociceptive systems.
Discomfort and pain are the sensations most commonly evoked from viscera. Most nociceptive signals that originate from visceral organs reach the central nervous system (c.n.s.) via afferent fibres in sympathetic nerves, whereas parasympathetic nerves contain mainly those visceral afferent fibres concerned with the non-sensory aspects of visceral afferent function. Noxious stimulation of viscera activates a variety of specific and non-specific receptors, the vast majority of which are connected to unmyelinated afferent fibres. ⋯ Visceral pain is the consequence of the diffuse activation of somato-sensory nociceptive systems in a manner that prevents accurate spatial discrimination or localization of the stimuli. Noxious stimulation of visceral receptors triggers general reactions of alertness and arousal and evokes unpleasant and poorly localized sensory experiences. This type of response may be a feature of sensory systems dominated by unmyelinated afferent inputs.