[Clinical features of 10 cases with phlyctenular keratitis].

We investigated 15 eyes of 10 patients with phlyctenular keratitis. The patients were 6 men and 4 women, and their ages ranged between 3 and 56 years (mean, 17.8 years). The follow-up periods ranged from 0.5 to 48 months (mean, 14 months). Clinically, complications in many cases were papillary hyperplasia in palpebral conjunctiva, meibomian gland infarct, chalazion, and blepharitis. Microbial examination from the lid margin before treatment revealed bacteria in 4 eyes of 4 patients out of 9 eyes of 8 patients. The level of serum specific IgE antibody was high in only 1 patient out of 6. We classified the clinical course into 3 stages, namely, infiltrative, nodule, and cicatricial stages. We also investigated the transition of the disease among the stages. All the cases of the infiltrative stage progressed to the nodule stage, and 92% of the nodule stage went on to the cicatricial stage. However 14% of the cicatricial stage cases reverted to the infiltrative stage and 7% to the nodule stage.

Changes in the microvasculature after mechanical pressure on the hamster cheek pouch.

The reaction of the microvasculature in the periodontal ligament to mechanical pressure is considered a very important phenomenon with respect to the biological background to orthodontic tooth movement. For clarification of the microvascular reaction to mechanical pressure, an experimental model that incorporated a hamster cheek pouch was established. This in vivo model solves some of the problems of other experimental models of the microvasculature of the periodontal ligament. Blood plasma permeation in this model was examined by means of a blue dye (pontamine sky blue), and histological observation was performed by light and transmission electron microscopy. Increased vascular permeability was observed within 30 min after removal of the mechanical stimulation. The threshold weight resulting in dye leakage was between 1 and 5 g applied for 60 min. From the histological observations, some large gaps between the endothelial cells in venules were found, while most basement membranes remained undisturbed. These observations suggest that the plasma leakage was due to mild traumatic injury to the endothelial cells. Both leukocytes and platelets were observed in the gaps between the endothelial cells in the venule. These types of microvascular reactions to mechanical pressure could initiate tissue changes in the periodontal ligament during orthodontic tooth movement.

[Matrix vesicles in membranous ossification].

Calcification process in membranous ossification was examined histologically by light and electron microscopies in comparison with that in enchondral ossification. The following results were obtained: 1) In the rat tibial articular cartilage, the extracellular matrix proceeding from the transitional to the hypertrophic zone consisted of the following three layers from the proximal: the first layer in which ruthenium red positive granules were densely populated and thin collagen fibrils diffusely arranged but few matrix vesicles were observed; the second one containing numerous matrix vesicles and slightly thick collagen fibrils; and the last one in which the thick collagen fibrils were observed while matrix vesicles and ruthenium red positive granules were few. 2) In the calcified regions in the extracellular matrix of MC3T3-E1 cells, the regions of alveolar new bone formation due to orthodontic tooth movement and the calcified regions in the interparietal suture expanded mechanically in vitro, the number of matrix vesicles was less than those in the regions of enchondral ossification. 3) Ruthenium red positive granules were fewer in the regions of alveolar new bone formation after the orthodontic tooth movement than in the calcified regions of cartilage. 4) The observation on MC3T3-E1 cells revealed the two different possibilities of the processes of calcification: the calcification induced by matrix vesicles as an initiator and that directly related to mineral deposit on the collagen fibrils.