European journal of pain : EJP
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Injured sensory axons trapped in a neuroma or freely regenerating in the distal nerve stump, frequently display ectopic mechanosensitivity, spontaneous impulse discharge or both. This abnormal neural activity is thought to contribute to spontaneous and movement-evoked neuropathic paraesthesias, dysaesthesias and pain, as well as to allodynia and hyperalgesia. ⋯ This suggests that mechanosensitivity and spontaneous firing are aspects of a single underlying pathophysiological process. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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The extent of surgical trauma was related to postoperative pain intensity in a previous study. However, more extensive surgical procedures with higher baseline pain intensity did not appear to influence the ability to document the additive analgesic effect of codeine when given with paracetamol, partly due to large interindividual variation in baseline pain intensity. The aim of the present study was to attempt to improve upside assay sensitivity in this dental pain model by: (1) selecting patients with high baseline pain intensity; and (2) closer supervision of outpatients>> drug intake and compliance with protocol. ⋯ More pain relief was revealed when codeine 60 mg was added to paracetamol 1000 mg on the following measures of effect: change of pain intensity with time (p<0.05, Mann-Whitney), sum of pain intensities (p=0.019), pain intensity difference (p=0.05), sum of pain intensity differences (p<0.05), pain reduction index (p<0.05) and global-evaluation score (p=0.006). The study confirms that this dental pain model, when controlled for sufficient and homogeneous baseline pain and patient compliance, does have sufficient upside assay sensitivity to discriminate between paracetamol with and without codeine. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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We have previously reported that intrathecal (i.t.) implantation of bovine chromaffin cells has an anti-allodynic effect in a rat model of mechanical and cold allodynia-like neuropathic pain after spinal cord injury. The technique of encapsulation of the cells by a semipermeable membrane has been developed recently. The present study was undertaken to investigate the effects of encapsulated bovine chromaffin cells on the allodynia-like pain in the same model. ⋯ The results indicate that spinal implantation of encapsulated xenogeneic chromaffin cells may be useful in treating some refractory painful states associated with spinal cord injury. Immunoisolation of chromaffin cells by a semipermeable membrane may inhibit immunorejection, prolong the survival of the cells and enhance their anti-allodynic effect. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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The formalin test is a well-established model for assessing nociceptive processes and analgesic drug effects. Previous studies have provided statistical validation of optimal procedures for conducting and scoring the rat formalin test. In the mouse model, formalin concentration has been subjected to validation studies. ⋯ Multiple regression analyses defined the optimal second-phase formalin response in outbred, Swiss-Webster mice as 15-35 min post formalin injection, and revealed that the second-phase response is best characterized by the cumulative time spent biting/licking the injected paw. Finally, paw physiological measures provided convergent evidence of nociceptive and antinociceptive processes in the mouse formalin test. Copyright 1998European Federation of Chapters of the International Association for the Study of Pain.