Shikaigaku

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In order to understand the functional significance of trigeminal nociceptive neurons in the intralaminar nuclei, their response characteristics were studied in the cat. Furthermore, we attempted to identify neurons relaying trigeminal nociceptive input to the intralaminar nuclei.
Experiments were carried out on cats anesthetized with urethane and chloralose. Single unit activities were recorded from the thalamus using glass capillary microelectrodes filled with 2% pontamine sky blue in 1M sodium acetate.
Trigeminal nociceptive neurons were found in the nuclei centralis lateralis, centralis medialis and parafascicularis of the intralaminar nuclei. They were excited by mechanical stimulation of the contra- or bilateral cornea at a strength above the human corneal pain threshold. Furthermore, they were frequently excited by noxious mechanical stimulation of the contra- or bilateral pinna, face and/or tongue. Tapping the nose dorsum and/or electrical stimulation of the canine dental pulp had excitatory effects in some trigeminal nociceptive neurons. These receptive field characteristics were similar to those of trigeminal nociceptive neurons in the caudal medulla oblongata. In addition, most of them were activated by noxious stimulation of the spinal nerve territory and by visceral sympathetic afferent nerves. Following electrical stimulation of the contralateral nucleus centralis lateralis, a majority of trigeminal nociceptive neurons in the dorsolateral part of the subnucleus reticularis ventralis of the caudal medulla oblongata were antidromically activated, suggesting that these nociceptive neurons relay trigeminal nociceptive input to the nucleus centralis lateralis.

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Microvascular changes during microangiopathy in the diabetic rat retina and gingivae, especially the inner marginal epithelium of the gingiva, were investigated under TEM utilizing microvascular casts prepared by the plastic injection method. The endothelium of the retinal capillaries was also investigated under TEM.
The progress of microangiopathy in the retinal capillaries was examined 10 weeks after injection of streptozotocin. Microangiopathy in the inner marginal epithelium closed up rapidly 20 weeks after streptozotocin injection. This was accomapanied by microvasculature changes.
Investigation of the retinal vascular architecture due to microangiopathy was helpful in determining the severity of the diabetic condition.

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Human permanent teeth were examined to investigated the qualitative and quantitative changes of glycosaminoglycans (GAG) in healthy and acute inflamed pulps. GAG composition was determined by electrophoresis on cellulose acetate strips. The ΔDi-4S/ΔDi-6S ratio in chondroitin sulfate (CS) after chondroitinase AC digestion was determined by fluorescence high-performance liquid chromatography.
The results obtained were as follows :
1) The GAG composition of both the healthy and inflamed dental pulps consisted of dermatan sulfate, CS-A (or C), heparan sulfate, and hyaluronic acid.
2) There was an increase in the amount of GAG (uronic acid) during pulpal inflammation. In particular, there was a greater increase in the amount of CS than of the other three components.
3) The ΔDi-4S/ΔDi-6S ratio was greater in the inflamed than in the healthy pulps.
From these results it appears that pulpitis affects the metabolic pathways of pulpal GAG, in particular the CS component.

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It is well-known that sagittal splitting of the ramus is effective for improvement of the occlusion and facial esthetics of mandibular prognathism associated with an open bite. We treated two mandibular prognathic cases associated with an open bite by orthognathic surgery. However, these two cases showed different post-operative results. We re-evaluated the initial morphology of these cases by Kamiyamas' analysis to elucidate the cause of this difference.
The first case was morphologically a skeletal open bite, although the maxillary anterior alveolar process compensated for the anterior open bite. In this case, post-oper-ative stability of the anterior segment of the mandible was satisfactory.
The open bite of the second case was due to hypoplasia of the mandibular anterior alveolar process. In this case, the orthognathic surgery brought about excessive stress in the soft tissues and muscles around the mandible resulting from the setback and counterclockwise rotation of this segment. Therefore, the clockwise rotation elongated the mandibular incisors, cuspids and first bicuspids during the intermaxillary fixation.
In order to prevent such relapses we should select surgical procedures which reduce excessive stress in the soft tissues and muscles around the mandible by analysing open bite cases by Kamiyamas' method.

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