Tadashi Yasuoka

Effect of estrogen replacement on temporomandibular joint remodeling in ovariectomized rats.

PURPOSE The investigation was performed to elucidate the effect of estrogen on the temporomandibular joint (TMJ) and to evaluate the therapeutic effect of 17beta-estradiol replacement in growing rats. MATERIALS AND METHODS Thirty 4-week-old female albino Wistar rats were divided into 3 groups. Ten rats were ovariectomized followed by intramuscular administration of 17beta-estradiol for hormone replacement (OVX + E2), 10 were sham operated (CTL), and 10 were ovariectomized without hormone replacement (OVX). Five rats from each group were killed at 1 and 2 weeks postoperatively, and the serum estrogen was determined to verify the adequacy of replacement. The temporomandibular joints of the age-matched sham-operated control and ovariectomized groups were histomorphometrically evaluated at the same periods. RESULTS In OVX animals, the thickness of the articular soft tissue was increased by a concomitant increase of the transitional and cartilage zones in the anterior and posterior portions at 1 and 2 weeks postoperatively. However, the bone volume was decreased in the anterior and posterior portions at 2 weeks after the surgery and the condyle was flattened. Replacement with 17beta-estradiol restored most of the histomorphometric parameters. The thickness of articular soft tissue was increased in the anterior portion by an increase in the cartilage zone in the OVX + E2 group at 2 weeks postoperatively. Increase of bone volume was found at 2 weeks after hormone replacement with a corresponding increased osteoid surface and decreased quiescent surface in the central portion at 1 week postoperatively. A flattened condyle was still noted at 2 weeks postoperatively in the OVX + E2 animals despite the hormone replacement. CONCLUSIONS Estrogen in a physiologic concentration may play an important role in TMJ remodeling. Progesterone may be indispensable for remodeling, particularly contributing to morphogenesis.

The effect of ovariectomy on the temporomandibular joints of growing rats

PURPOSE This investigation studied the effects of ovariectomy, on the temporomandibular joints (TMJ) of young rats. MATERIALS AND METHODS Four-week-old female Wistar rats were ovariectomized and killed at the intervals of 1, 2, 4, and 8 weeks postoperatively. Histomorphometric study of the TMJ was performed in a synchronous manner with an age-matched sham-operated control group. The serum levels of estrogen, calcitonin, and C-terminus parathyroid hormone were also determined. RESULTS In the sham-operated control group, the serum levels of estrogen and calcitonin increased with age. An increase of the bone volume, with a concomitant increase of the osteoid surface, was observed at 12 weeks. Thickness of the articular soft tissue was decreased with increasing age. In the ovariectomized animals, serum estrogen was not detected during the experiment. A biphasic change in the parathyroid hormone level, with decreases at 1 and 2 weeks after the ovariectomy and increases at 4 and 8 weeks postoperatively, was observed, whereas a constant value was noted in the calcitonin level. Thickness of the articular soft tissue was increased in the anterior and central portions of the condyle at 1, 2, and 4 weeks after the ovariectomy, whereas no appreciable changes were observed in the posterior portion. The bone volume was decreased during the experiment, particularly in the posterior portion. An osteophyte in the anterior region was also observed 8 weeks postoperatively. CONCLUSIONS Estrogen deficiency in rats during puberty predisposes to alterations of the TMJ through changes in serum calcitonin and parathyroid hormone levels.

DIRECT ACTION OF MELATONIN ON HEN OVARIAN GRANULOSA CELLS TO LOWER RESPONSIVENESS TO LUTEINIZING HORMONE

Abstract The presence of a melatonin-binding component in the membrane fraction of the ovarian granulosa cells of hens that has characteristics of a receptor such as high affinity, limited capacity, reversible binding, and binding specificity was demonstrated by radioligand binding assays. When the cells were incubated in vitro with various concentrations of luteinizing hormone (LH) in the presence and absence of melatonin (1 and 5 nM), the dose-response curve for the LH-stimulated progesterone production was shifted to a higher concentration of LH: ED50 of LH was approximately two times greater in the presence of melatonin. The results suggest a direct action of melatonin on the ovarian granulosa cells of the hen to lower the responsiveness to LH for progesterone production.

Histomorphometric study of trabecular bone remodeling during condylar process fracture healing in the growing period: Experimental study

Trabecular bone remodeling during condylar fracture healing in the growing period was analyzed by histomorphometry with a synchronous system. Data from the study showed displacement of the fractured condyle was compensated by the changes in remodeling ascribed to the pubertal spurt of growth, and that such remodeling still continued even after clinical healing. The regional acceleratory phenomenon, evolved to potentiate tissue healing, was observed 1 week after induction of the fracture. Mesenchymal cells were presumably modulated into chondroblasts that promoted endochondral ossification. It was concluded that trabecular bone remodeling plays an important role in healing of condylar fractures during the growth period.

Calcitonin receptor binding properties in bone and kidney of the chicken during the oviposition cycle.

The binding property of calcitonin (CT) in the membrane fraction of calvaria and kidney of egg‐laying and nonlaying hens was analyzed using a [125I]CT binding assay system. Binding properties of CT receptors in both tissues satisfy the authentic criteria of a receptor‐ligand interaction in terms of specificity, reversibility, and saturation. Scatchard plots revealed a single class of binding sites. Values of the equilibrium dissociation constant (Kd) and binding capacity (Bmax) in laying hens showed a decrease during the period between 3 h before and 2 h after oviposition. No change was observed in nonlaying hens. In vivo administration of 17β‐estradiol or progesterone caused the decrease in Kd and Bmax values. The results suggest that the binding affinity and capacity of the CT receptor in the calvaria and the kidney of the hen may be modulated by the ovarian steroid hormone.

Chondroma of the tongue. Report of a case.

A case of chondroma which occurred in the midline of the dorsum of the tongue in a 40-year-old Japanese male is reported together with a review of the literature. Histological investigation revealed that this lingual chondroma had the characteristics of hyaline cartilage. We regard the metaplastic transformation theory as the best explanation of histogenesis of lingual chondroma at the lateral margin, while cartilaginous rests are the origin of lingual chondroma on the dorsum of the tongue.

Myeloperoxidase deficiency as a predisposing factor for deep mucocutaneous candidiasis: A case report

Abstract Myeloperoxidase deficiency (MPD) is an immunosuppressive condition; the bactericidal ability of neutrophils is reduced in spite of their normal phagocytic activity. 1,2 Susceptibility to candidal and staphylococcal infection has been the chief problem resulting from MPD. 1 Candidiasis is not a rare condition in the oral cavity. Deep candidiasis, however, is uncommon compared with the superficial form, and seldom is seen in the oral cavity. 3 The following report describes a case of alveolar pyogenic granuloma in the right maxillary anterior region accompanied by an external fistula to the infraorbital area, which was caused by infection with Candida albicans in a patient with MPD.

Fibrous dysplasia in the maxilla: possible mechanism of bone remodeling by calcitonin treatment

The long-term follow-up case of monostotic fibrous dysplasia of the maxilla in a 10-year-old girl is described with her endocrinologic data and therapeutic consequence of calcitonin administration in association with surgical interventions. The fibrous dysplasia tends to become more quiescent or static after skeletal growth ceases, but the causative has been still unknown to date. In this case reported changes of calciotropic hormones in the serum were well corresponding to the ceasing of the tumor growth at the puberty and reflected to the calcitonin administration. Although calcitonin has been applied to the fibrous dysplasia associated with McCune Albright syndrome, no histologic changes have been described after the calcitonin treatment. This report might be the first description of bone remodeling after the calcitonin treatment for the fibrous dysplasia of the maxilla in immature people. Data of this case may provide a clue to the pathogenesis of fibrous dysplasia. Surgical intervention can be performed after the local bone calcification by a calcitonin treatment, because of alleviation of vigorous hemorrhage by the bone remodeling.

Breast angiosarcoma metastatic to the maxillary gingiva

A case of breast angiosarcoma metastatic to the maxillary gingiva is reported. A review of the literature revealed only three previously reported cases. Angiosarcomas often present as benign lesions. The surgeon should maintain a high level of vigilance when patients present with oral lesions and a history of breast tumor.

A Vasoactive Intestinal Peptide Binding Component in Hen Granulosa Cells

Abstract In radioligand assays, the vasoactive intestinal peptide (VIP) binding component in the membrane fraction of granulosa cells of the ovary of the hen was shown to possess characteristic properties of a receptor, such as reversible binding, binding specificity, high-affinity, and limited capacity. The binding site was of a single class. The binding affinity was higher in the largest (F1) and the second largest follicle (F2) than in the third largest follicle (F3), and the binding capacity was greater in F2 and F3 than in F1. During the ovulatory cycle, changes in affinity and capacity were observed only in F1 shortly before ovulation. The results suggest the presence of VIP receptor in the hen granulosa cells and its binding is assumed to be related to the follicular growth and ovulation.