Minoru Kawanishi

The maintenance of normoglycemia has been reported to reduce painful sensations in diabetic subjects. This suggests that lowering the tissue glucose concentration might inhibit the increased cutaneous nociceptor activities seen in a diabetic conditin. To test this hypothesis, we studied the effect of changing the glucose concentration in the superfusate of in vitro preparations (high, HG: 20 mM or normal glucose, NG: 6.7 mM) on the mechanical response of C-fiber polymodal receptors (C-polymodal receptors). Single fiber activities of C-polymodal receptors were recorded from skin-nerve in vitro preparations of streptozotocin-induced diabetic and age-matched control rats. Pressure stimulation was applied to the receptive field by a servo-controlled mechanical stimulator. C-polymodal receptors from diabetic preparations superfused with HG-solution showed increased spontaneous activity, lowered response threshold, increased response magnitude and a less adaptive response pattern to mechanical stimulation compared with those from control preparations superfused with NG-solution. C-polymodal receptors from diabetic preparations superfused with NG-solution showed no such changes. The responsiveness of C-polymodal receptors from control preparations was not different in NG- or HG-conditions. These data demonstrated that normalization of the glucose concentration normalized the responsiveness of C-polymodal receptors in diabetic animals. This response may be associated with the fact that normoglycemia reduces painful sensations in diabetic subjects. (C) 2002 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.

The maintenance of normoglycemia has been reported to reduce painful sensations in diabetic subjects. This suggests that lowering the tissue glucose concentration might inhibit the increased cutaneous nociceptor activities seen in a diabetic conditin. To test this hypothesis, we studied the effect of changing the glucose concentration in the superfusate of in vitro preparations (high, HG: 20 mM or normal glucose, NG: 6.7 mM) on the mechanical response of C-fiber polymodal receptors (C-polymodal receptors). Single fiber activities of C-polymodal receptors were recorded from skin-nerve in vitro preparations of streptozotocin-induced diabetic and age-matched control rats. Pressure stimulation was applied to the receptive field by a servo-controlled mechanical stimulator. C-polymodal receptors from diabetic preparations superfused with HG-solution showed increased spontaneous activity, lowered response threshold, increased response magnitude and a less adaptive response pattern to mechanical stimulation compared with those from control preparations superfused with NG-solution. C-polymodal receptors from diabetic preparations superfused with NG-solution showed no such changes. The responsiveness of C-polymodal receptors from control preparations was not different in NG- or HG-conditions. These data demonstrated that normalization of the glucose concentration normalized the responsiveness of C-polymodal receptors in diabetic animals. This response may be associated with the fact that normoglycemia reduces painful sensations in diabetic subjects. © 2002 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.

Rats rendered diabetic by streptozotocin (STZ) show allodynia and hyperalgesia and thus, have been offered as a model of pain in diabetic neuropathy. However, recent electrophysiological studies on these rats found that C-fiber nociceptors were not consistently hyperexcitable to mechanical stimulations by von Frey hairs and that there was no change in their response thresholds. In the present study, we used rat skin-saphenous nerve in vitro preparations, in which the receptive fields of identified single C-polymodal receptors (CPRs) can be accurately stimulated with a servo-controlled mechanical stimulator. Single fiber recordings from CPRs were performed in diabetic rats with an increased behavioral nociceptive response 7-19 days after STZ injection. The proportion of units with spontaneous activity and the magnitude of this activity increased in the diabetic preparations. The response thresholds of CPRs were significantly decreased with ramp-pressure stimulation and their response magnitude to the suprathreshold stimulation was significantly increased in diabetic rats. In addition, the response pattern to mechanical stimulation was also changed to a non-adapting type. These findings suggest that changes in CPRs contribute to the enhanced nociception observed in the early stage of diabetic neuropathy. (C) 2002 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Injury to elongated, upper convex, isolated, mobile, and prosthetic (crown & bridge) teeth may occur during oro-tracheal intubation under general anesthesia.<br>Three types of protectors were studied in 32 of the 192 patients given general anesthesia from June to October 1993 at our hospital.<br>The first type, "Modeling Compound", proved to be useful, but some problems were noted. The second type, "premade protector", was not always suitable for elongated, upper convex, or isolated teeth or individual irregularities.<br>The third type, "Pressed custom-made protector", can be adapted for all patients, but it is costly and time consuming prior to the operation.<br>In conclusion, in addition to "Modeling Compound" which is currently being used at our hospital, we are adopting the "Pressed custom-made" type as an additional protector.