Search PubMed⌕ Search

Biomedical subjects

H Mitani

Publications and source records attributed to H Mitani.

At least 127 records · Page 7Linked to original sources
PubMed1995

Surgical-orthodontic treatment in Class II, division 2, malocclusion: a case report involving pretreatment and posttreatment evaluation of temporomandibular dysfunction.

The case of a patient who had a significant Class II, division 2, malocclusion and experienced myofascial pain dysfunction is presented. The patient was a 22-year-old Japanese woman who complained of pain and fatigue in her masticatory muscles. During presurgical orthodontic treatment, a one-tooth osteotomy was utilized to correct the lingual inclination of an ankylosed maxillary central incisor. The surgery consisted of intrusion of the anterior segment of the maxilla, intrusion of the anterior segment of the mandible, mandibular advancement by sagittal split ramus osteotomy, and trimming of the gonial angles. Postoperatively, her facial appearance and occlusion were good. Furthermore, the function of the temporomandibular joints was improved and the symptoms of myofascial pain and dysfunction disappeared.

Adult↗
PubMed1994

The predisposing gene of the Eker rat inherited cancer syndrome is tightly linked to the tuberous sclerosis (TSC2) gene.

The Eker rat is a promising animal model of cancer predisposition syndromes. In this study, using 129 backcross animals, we have established a new conserved linkage group on rat 10q and human 16p13.3 whereby the Eker mutation was found to be tightly linked to the tuberous sclerosis (TSC2) gene. This will be the first step toward the positional cloning and identification of the predisposing Eker mutation.

Animals↗
PubMed1994

A novel cancer predisposition syndrome in the Eker rat model.

Hereditary renal carcinomas (RCs) develop in virtually all Eker rats by the age of one year. Investigation of extrarenal primary tumors occurring in Eker rats late in life (at 2 years) additionally revealed pituitary adenomas (17/31 = 54.8% (carrier) vs 7/32 = 21.9% (non-carrier siblings of affected animals), P < 0.01), sarcomas of the spleen (21/31 = 67.7% vs. 0/32 = 0%, P < 0.001) and sarcomas (of probable stromal origin) of the uterus (8/17 = 47.1% vs. 0/15 = 0%, P < 0.01). Thus, the Eker rat might provide a novel animal model of cancer predisposition syndromes.

Animals↗
PubMed1994

Allelic loss at the predisposing gene locus in spontaneous and chemically induced renal cell carcinomas in the Eker rat.

Hereditary renal carcinoma (RC) in the rat, originally reported by Eker in 1954, is an example of a Mendelian dominant predisposition to a specific cancer in an experimental animal. We previously reported that ionizing radiation induces additional tumors in a linear dose-response relationship, suggesting that in heterozygotes two events (one inherited, one somatic) are necessary to produce tumors. Recently, the predisposing gene has been mapped to rat chromosome 10. This study was designed to examine loss of heterozygosity (LOH) at chromosome 10 in the RCs developed from hybrid F1 rats carrying Eker mutation. In spontaneous RCs, 6 of 10 (60%) showed loss of the wild-type allele covering over 30 cM, consistent with two-hit hypothesis. Individual tumors have different patterns of LOH even from the same kidney, showing independent clonal origins of RCs. In contrast, none of N-ethyl-N-nitrosourea-induced RCs had allelic loss (0 of 9 = 0%, P < 0.01). Thus, the nature of the second event differs between spontaneous and chemically induced tumors in the Eker rat. These results suggest that chemically induced tumors in experimental animals involve intragenic mutations and so do not cause LOH of syntenic markers. Interestingly, 1 of 5 spontaneous pituitary tumors that developed in the Eker rat showed LOH for chromosome 10 markers.

Alleles↗
PubMed1994

Replication sites as revealed by double label immunofluorescence against proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU) in synchronized CHO cells and vincristine-induced multinucleate cells.

Double label immunofluorescence against PCNA and BrdU clearly revealed several characteristics of DNA replication sites in synchronized CHO cells. We observed that the distribution of replication sites changed from early to late S phase, particularly in the nucleolar and perinuclear regions, and the amount of PCNA in each replication site markedly decreased or disappeared with the progression of S phase. Although co-localization of PCNA and BrdU was usually seen, the intensity of fluorescence occasionally differed between the labeled PCNA and BrdU, particularly in late S phase. Based on the assumption that such a difference may reflect a different configuration of the chromatin, we propose that the brightly granular fluorescent staining of PCNA or BrdU in early S phase indicates a condensed segment of euchromatin. In the late S phase nucleus, we clearly observed a chromatin-like structure in the late replicating segments of heterochromatin in anti-PCNA stained material. In vincristine-induced multinucleate cells, a discrepancy between PCNA-distribution and BrdU-incorporation in sister nuclei was sometimes seen. Such observations indirectly support the following two mechanisms for premature chromosome condensation proposed by others: asynchronous initiation of DNA synthesis; and a difference in the rate of DNA synthesis. In addition, the finding that BrdU was not incorporated into sites that had PCNA deposits suggests a third mechanism: the local disturbance of replication sites. Furthermore, unusual distribution patterns for replication sites suggest that the nucleation process in multinucleate cells differs from that in normal cells.

Animals↗
PubMed1994

Relationship between the induction of proteins in the HSP70 family and thermosensitivity in two species of Oryzias (Pisces).

A cultured fish cell line, CE, derived from Oryzias celebensis, which lives in a tropical zone, was more heat-resistant than the OL32, which were derived from the Japanese medaka, Oryzias latipes which lives in a temperate zone. Protein synthesis in OL32 cells was also more heat-sensitive than that in CE cells. The relative levels in proteins of the HSP70 family and the ability of cells to tolerate severe heat treatment after a conditioning heat treatment were examined. Twenty-four hours after conditioning heat treatment, both cell lines retained thermotolerance even though three proteins in the HSP70 family had returned to their control levels.

Animals↗
PubMed1994

Role of endogenous PGE2 in osteoblastic functions of a clonal osteoblast-like cell, MC3T3-E1.

MC3T3-E1 cells actively synthesized and released prostaglandin E2 (PGE2) during culture. PGE2 release was minimal on day 9 and gradually increased with culture up to day 27. DNA content gradually increased until day 27. Alkaline phosphatase (ALP) activity increased up to day 15 and decreased thereafter. In contrast to the decrease in ALP activity, calcium accumulation increased rapidly after day 21, possibly due to mineralization by the cells. Indomethacin, a cyclooxygenase inhibitor, blocked PGE2 production completely at concentrations higher than 0.3 mumol/L. In the presence of indomethacin (3 mumol/L), DNA content was slightly decreased on day 27. Furthermore, ALP activity on day 15 was greater than that of the control and this high activity was maintained until day 27. However, calcium accumulation was not affected by the addition of indomethacin. These results suggest that endogenous PGE2 down-regulates ALP activity and slightly stimulates the proliferation of MC3T3-E1 cells as an autocrine mediator, although it does not directly influence the cells' mineralizing activity.

Alkaline Phosphatase↗
PubMed1994

Anchorage and retentive effects of a bisphosphonate (AHBuBP) on tooth movements in rats.

The purpose of this study was to examine the effect of 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHBuBP), a potent blocker of bone resorption, on orthodontic tooth movements in rats. In the first experiment, the right and left upper first molars were moved buccally for 3 weeks with a uniform standardized expansion spring under systemic administration of AHBuBP every other day. The total tooth movement during the 3-week experimental period was 40% of that in the control at a dose of 0.5 mg P/kg. In the second experiment, the right and left upper first molars were first moved buccally for 3 weeks without AHBuBP. The spring was then removed and administration of AHBuBP was initiated. The total relapse movement during the 3-week experimental period was 50% of that in the control at a dose of 0.5 mg P/kg. Results of the first and second experiments were both dose dependent. Histologic examination showed that in the experimental animals fewer osteoclasts appeared on the alveolar bone surface, and both bone resorption and root resorption were inhibited. Inhibition of tooth movement was also observed when AHBuBP was applied topically. These results suggest that AHBuBP could be useful in enhancing anchorage or retaining teeth in orthodontic treatment.

Alendronate↗
PubMed1994

The effects of growth-inhibiting treatments on photorepair in cultured fish cells.

Goldfish cells (RBCF-1) cultured at different cell densities were harvested and their photorepair (PR) abilities were examined in terms of survival. Photorepair ability gradually increased during the phase of logarithmic growth, reaching a maximum in cells at the confluent state. This enhancement of PR ability disappeared 12 h after replating of cells in fresh medium. A number of growth-inhibiting treatments (serum depletion, UVC, hydroxyurea [HU], change in incubation temperature) were tested for their ability to induce PR. The treatment of cells with HU and serum depletion induced PR while the other treatments did not. The increase in the ability to perform PR after treatment with HU or serum depletion returned to normal levels more rapidly than that after fluorescent light treatment.

Animals↗
PubMed1994

Effects of topical administration of a bisphosphonate (risedronate) on orthodontic tooth movements in rats.

In orthodontics, undesirable movement of anchor teeth during tooth movement and relapse of moved teeth after treatment are the main causes of unsuccessful results. If these tooth movements could be prevented with pharmacological agents, a less complex orthodontic force system and less extensive retention would be required. The purpose of this study was to examine the effect of topical administration of a bisphosphonate (risedronate), a potent blocker of bone resorption, on orthodontic tooth movements in rats. In the first experiment, both the right and left upper first molars were moved buccally with a standardized expansion spring under administration of risedronate. Risedronate solution was injected into the subperiosteum area adjacent to the left upper first molar. The right first molar served as a control with an injection of 0.9% NaCl solution. The topical administration of risedronate caused a significant and dose-dependent reduction of tooth movement after the orthodontic force was applied. In the second experiment, the right and left upper molars were first moved buccally for three weeks. The spring was then removed, and administration of risedronate was begun. The topical administration of risedronate inhibited relapse of the tooth in a dose-dependent manner. The administration of risedronate did not affect either overall growth of the animals or longitudinal growth of tibiae. These results suggest that topical application of risedronate may be helpful in anchoring and retaining teeth under orthodontic treatment.

Administration, Topical↗
PubMed1994

[Cholecystokinin receptors involved in the central and peripheral nervous control mechanisms in gastric acid secretion].

Cholecystokinin (CCK) has a unique pharmacological profile as a "brain-gut peptide hormone", and recent development of specific non-peptide antagonists prompted us to investigate the role of the receptors of this peptide in nervous control mechanisms of gastric acid secretion. CCK-8 induced a distinctive acid secretory response after intracerebroventricular (i.c.v.) administration, as well as after intravenous infusion in the perfused stomach preparation in rats. L364718, a CCKB-receptor antagonist, had an inhibitory effect against CCK-8 when applied i.c.v., while L365260, a CCKB-receptor antagonist, had no influence, suggesting the apparent dominant control of CCKA receptors in the central nervous system on gastric acid secretion. However, L364718 caused remarkable potentiation in the acid secretory response to the intravenous CCK-8 infusion, and L365260 significantly inhibited the CCK-8-stimulated acid secretion. The potentiation of the acid secretory response to CCK-8 by the CCKA antagonist was completely blocked by vagotomy or atropine, as well as hexamethonium. Thus it was suggested that a vagal control mechanism was involved in the potentiation. Denervation of capsaicin-sensitive primary afferent nerve by repeated capsaicin injection also decreased the potentiated response to CCKA antagonist. This seems to suggest the involvement of the vago-vagal reflex in the control of gastric acid secretion by endogenous CCK. Ketanserin, a serotonin 5-HT2/1C-receptor antagonist, showed a distinctive inhibition of acid secretion induced by CCK-8 (i.c.v.), suggesting the involvement of serotonergic control of acid secretion in the CCK-8 action. Current developments in the research in this field were briefly reviewed in relation to our findings.

Animals↗
PubMed1994

Photorepair and excision repair removal of UV-induced pyrimidine dimers and (6-4) photoproducts in the tail fin of the medaka, Oryzias latipes.

Induction and repair of UV-B induced DNa damage in the tail fin of the Medaka, were examined immunohistochemicaly and by the enzyme-linked immunosorbent assay (ELISA). UV-induced DNA damage was detected only in the outermost layer of epithelial cells and did not differ in fishes having different degree of melanization. Both pyrimidine dimers and (6-4) photoproducts in the fin cells were removed by excision repair in the dark, the excision of (6-4) photoproducts being about twice as efficient as that of pyrimidine dimers. The rate of excision repair of UV-induced lesions in fin tissue was three to four times that in cultured Medaka cells, OL32. In the fin cells, reductions in the numbers of pyrimidine dimers and (6-4) photoproducts were seen after treatment with fluorescent light, whereas less reductions of pyrimidine dimers and no reductions of (6-4) photoproducts were observed in OL32 cells.

Animals↗
PubMed1994

Microprocessor-based memory device for ambulatory heart rate and physical activity recording.

Using microprocessor techniques, a portable digital memory device has been designed for the ambulatory monitoring of heart rate and physical activity. The device consists of a microprocessor, an ECG amplifier to record the heart rate and an accelerometer to detect the physical activity. This accelerometer is piezo-resistive and is suitable for ambulatory physical activity recording, because this sensor requires low electrical power, has high durability and wide frequency response (DC approximately 1.2 kHz). Changes in heart rates and physical activity in daily life have been successfully recorded.

Computer Storage Devices↗
PubMed1993

Genetic predisposition to transplacentally induced renal cell carcinomas in the Eker rat.

N-Ethyl-N-nitrosourea-induced transplacental renal carcinogenesis in the rat results primarily in Wilms' tumors, apparently because primitive nephroblasts are the preferred target. Our question is whether N-ethyl-N-nitrosourea-induced mutations in the fetal kidney would increase the number of adult-type renal cell carcinomas in the Eker rat, which is heterozygous for a mutation that predisposes to renal cell carcinoma. Surprisingly, renal cell tumors but no Wilm's tumors began to appear from as early as 1 week after birth. Thus, the inheritance of a renal cell carcinoma mutation determines the specificity of tumor histology even with in utero carcinogenesis.

Animals↗
PubMed1993

Usefulness of plasma beta-endorphin level, pain threshold and autonomic function in assessing silent myocardial ischemia in patients with and without diabetes mellitus.

The differences between diabetic and nondiabetic patients with silent myocardial ischemia were investigated. Based on the results of previous exercise testing, a total of 110 patients (15 diabetic and 95 nondiabetic) with exercise-induced myocardial ischemia were divided into the following 3 groups: 15 diabetics with silent myocardial ischemia, 49 nondiabetics with silent myocardial ischemia, and 46 nondiabetics with anginal symptoms. All patients underwent treadmill exercise testing and 24-hour ambulatory electrocardiographic recording. Before and during exercise, blood samples from the antecubital vein were obtained to determine the plasma beta-endorphin levels, and the pain threshold of each patient was measured with the electrical skin stimulation test. Furthermore, with regard to the ambulatory electrocardiographic recording, the mean of the SDs of all normal sinus RR intervals during successive 5-minute recording periods over 24 hours was analyzed and considered as an index of the autonomic function. The plasma beta-endorphin level during exercise was significantly greater in nondiabetic patients with silent ischemia than in diabetic ones. The SD mean was significantly less in the diabetic group than in the 2 nondiabetic ones. The findings suggest that the role of beta endorphin in diabetic patients with silent myocardial ischemia may be less significant than in nondiabetic ones; therefore, a diabetic neuropathy that affects the autonomic pain fibers that innervate the heart may be involved in the mechanism of silent myocardial ischemia in diabetics.

Aged↗
PubMed1993

Presence of chondroid bone on rat mandibular condylar cartilage. An immunohistochemical study.

Immunohistochemical techniques were used to examine the locations of type I and type II collagens in the the most anterior and the posterosuperior regions of the mandibular condylar cartilages of young and adult rats. Large ovoid and polygonal cells, which were morphologically different from any of the neighboring cells, e.g., mature or hypertrophied chondrocytes, osteoblasts, or fibroblasts, were observed at the most anterior margin of the young and adult condylar cartilages. In the extracellular matrix (ECM) of this area, an eosinophilic staining pattern similar to that in bone matrix was observed, while the peripheral ECM showed basophilic staining and very weak reactivity to Alcian blue. Immunohistochemical examination showed that the ECM was stained heavily and diffusely for type I collagen, while a staining for type II collagen was faint and limited to the peripheral ECM. Two different staining patterns for type II collagen could be recognized in the ECM: one pattern revealed a very faint and diffuse reaction while the other showed a wak rim-like reaction. These staining patterns were markedly different from those in the cartilaginous cell layer in the posterosuperior area of the condylar secondary cartilage, which showed faint staining for type I collagen and a much more intense staining for type II collagen. These observations reveal the presence of chondroid bone, a tissue intermediate between bone and cartilage tissues, in the mandibular condylar cartilage, and suggest the possibility of osteogenic transdifferentiation of mature chondrocytes.

Animals↗
PubMed1993

Growth of mandibular prognathism after pubertal growth peak.

This study deals with the growth changes of the Japanese face associated with mandibular prognathism during 3 years after the pubertal growth peak. The investigation was based on the serial lateral cephalometric roentgenograms of prognathic and normal males and females, respectively. Maturational stages of the pubertal growth were determined individually by the ossification events taken from hand-wrist radiographs. Results indicate that the morphologic characteristics of the mandibular prognathism, which are established before the pubertal growth peak, are strongly maintained during the period studied. However, mandibular prognathism seems to show a manner of growth change fairly similar to that of the normal after the pubertal growth peak.

Adolescent↗