Hiroko Hiranuma

Cemento-osseous dysplasia of the jaws in 54 Japanese patients: A radiographic study

OBJECTIVE The aim of this study was to describe the radiographic patterns of cemento-osseous dysplasia. STUDY DESIGN Fifty-four patients affected with benign fibro-osseous jaw lesions that showed periapical radiopacities and/or radiolucencies in a focal or a multiplex form were studied. The clinical, radiographic, and histopathologic features of the patients with cemento-osseous dysplasia were retrospectively studied. Radiographic features of the cemento-osseous dysplasia lesions were classified according to the appearance of calcified bodies. Radiographic visibility of periodontal ligament spaces of related teeth was assessed. RESULTS Forty-nine (91 %) of the 54 patients were women. The mean age of the total group was 50.8 years, and that of the male group was 64.6 years. The cemento-osseous dysplasia lesions could be classified into 6 types radiographically. Eighteen patients had at least 2 or more types of cemento-osseous dysplasia lesions. Of 147 related teeth, 142 had periodontal ligament spaces clearly visible. Six of 9 patients who had a total of 25 teeth with active hypercementosis showed concomitant occurrence of other types of cemento-osseous dysplasia lesions. Biopsy specimens showed various amounts of bonelike and cementumlike tissues. CONCLUSIONS It is likely that cemento-osseous dysplasia consists of 3 variations of a single entity, all with the same unknown cause. In one variation, the entity originates from the periodontium; in another, it is of medullary bone origin; and in the third it results from the simultaneous involvement of both tissues.

EFFECTS OF INTERLEUKIN-6 ON PROLIFERATION AND PROTEOGLYCAN METABOLISM IN ARTICULAR CHONDROCYTE CULTURES

Interleukin‐6 (IL‐6) levels are markedly increased in the synovial fluid of patients with rheumatoid arthritis or osteoarthritis. However, the effects of IL‐6 on proliferation and proteoglycan metabolism in articular cartilage are not known. We demonstrated here the effects of human recombinant (hr) IL‐6 on proliferation and proteoglycan metabolism in rabbit articular chondrocyte cultures. In vitro, these cells proliferated and produced abundant extracellular matrices. We found that 1–10ng/ml of hrIL‐6 inhibited proliferation to approximately 65% of control levels and suppressed colony formation induced by bFGF in soft agarose. The same concentration of hrIL‐6 depressed proteoglycan synthesis to approximately 60% of control levels. Moreover, hrIL‐6 significantly enhanced proteoglycan degradation induced by hrIL‐1β, although hrIL‐6 alone did not affect proteoglycan degradation. These findings suggest that IL‐6 is a negative regulator for chondrocyte proliferation and articular cartilage metabolism.

EFFECT OF X-RAY IRRADIATION ON PROLIFERATION AND DIFFERENTIATION OF OSTEOBLAST

Summary We exposed the osteoblast-like cell line, MC3T3-E1, to 1-to 10-Gy X-ray. Irradiation at doses of 5-Gy dose or more decreased the DNA content of cells at the proliferation stage, confluence, and post-proliferation stages. The alkaline phosphatase activity, conversely, was increased by irradiation, and the calcium content of irradiated cells was greater than that of nonirradiated. These findings suggest that irradiation induces terminal differentiation and calcification of osteoblasts.

A unique case of desmoplastic ameloblastoma of the mandible: report of a case and brief review of the English language literature.

A unique case of desmoplastic ameloblastoma is reported from the clinical, radiographic, and histologic viewpoints. The patient was a 56-year-old man who complained of a painless swelling on the buccal aspect of the left mandible. Periapical and panoramic radiographs revealed a rounded, slightly radiolucent area with blurred osteosclerotic margins. Occlusal radiograph and computed tomography images disclosed buccal bone expansion outlined by thinned cortices. Computed tomography images exhibited an enhanced area in the anterior portion of the lesion. Interestingly, the coronal computed tomography images revealed a close relationship between the periodontal membrane of the left mandibular second premolar and the enhanced area. Biopsy specimens from the anterior portion of the lesion displayed typical histologic features of the desmoplastic variant of ameloblastoma. However, those from the posterior portion disclosed a large cystic formation. Oxytalan fibers were identified in the stromal tissue of the tumor, which suggested that the tumor arose from the epithelial rests of Malassez in the periodontal membrane of the related tooth. We also reviewed previously reported 41 cases. In 36 of 38 cases in which the location was specified, the tumor was found in the anterior to premolar region of the maxilla or mandible. A radiographic description was given in only 29 previous cases, 28 of which involved multilocular lesions. No cyst as large as the one in the present case was found among the previously reported desmoplastic ameloblastomas. Although the present case deviates from the usual desmoplastic variant of ameloblastoma in terms of locus, radiologic appearance, and cyst formation, it still meets the histologic criteria for this variant in both the stromal and epithelial components.

Inhibition of Chondrocyte Terminal Differentiation and Matrix Calcification by Soluble Factors Released by Articular Chondrocytes

Abstract. Chondrocytes do not undergo terminal differentiation in normal articular cartilage, whereas growth plate chondrocytes synthesize ALPase and induce matrix calcification terminally. Articular chondrocytes in osteoarthritic joints have been reported to express the terminal differentiation phenotypes, suggesting that terminal differentiation of articular chondrocytes is inhibited in normal joints. In the present study, we investigated the underlying inhibitory mechanism of the terminal differentiation in articular cartilage using a culture on type II collagen-coated dishes or a novel culture model on Millipore filters. ALPase activity increased from day 7 to day 8 in growth plate chondrocyte cultures on the collagen-coated dishes, but not in articular chondrocyte cultures. The ALPase expression of growth plate chondrocytes on the collagen-coated dish was completely inhibited when the same number of articular chondrocytes was mixed in the growth plate chondrocyte cultures. When articular chondrocytes or growth plate chondrocytes were maintained on Millipore filters held in 16-mm dishes, they started to synthesize ALPase. The ALPase expression of the chondrocytes on Millipore filters was inhibited by the presence of articular chondrocytes maintained on the bottom collagen-coated substratum in the same dishes. These results indicate that factors that diffused into the medium through the Millipore filters are involved in the inhibition of terminal differentiation. Since the conditioned medium from articular chondrocyte cultures did not affect the ALPase expression, it is considered that the soluble factors, which are continuously released from articular chondrocytes, are responsible for the inhibition of terminal differentiation.

Analysis of genomic instability in squamous cell carcinoma of the head and neck using the random amplified polymorphic DNA method

Using the random amplified polymorphic DNA (RAPD) method, we identified genomic instability in head and neck squamous cell carcinoma (HNSCC) tissues. We extracted DNA from tumor and corresponding normal tissues of 30 HNSCC patients and amplified with ten random 10-mer arbitrary primers by the RAPD method. Genomic instabilities, which appeared as banding pattern changes between normal and tumor DNA, were detected by at least one primer in all tumor tissues. Moreover, there was significant correlation between the frequency of genomic instability and the degree of tumor differentiation. These results indicate a possible association of genomic instability with malignant potential of head and neck cancer.

Radiographic changes during bone healing after mandibular fractures

The study aimed to find out the best time to undertake radiological follow-up examinations and remove fixation materials after fractures of the mandible through a retrospective study of radiographs. Serial radiographs of 325 fracture sites in 231 patients over a 10-year period were examined. Outcome was measured by radiographic features of healing at less than 2, 2-3, 3-4, and 4 or more months. Osteogenic change (osteogenesis and union) was the best radiographic criterion for evaluating follow-up radiographs. This change started to predominate 1-2 months after injury in patients less than 18 years of age (21/31, 68%) and 2-3 months after injury in older patients (21/25, 84%). Overall, union was noted in 98 of 115 patients (85%) 3 months or more after the fracture. We recommend follow-up radiographic examination to confirm clinical judgement during the fifth week after a mandibular fracture in patients less than 18 years of age, and the ninth week for older patients. The fixation materials should be removed during the fifth month after injury.

Changes in phenotypic expression of osteoblasts after X irradiation.

Changes in the phenotypic expression of osteoblasts after X irradiation were investigated. Osteoblast-like MC3T3-E1 cells at the actively proliferating, confluent and postproliferation stages were subjected to 10 Gy X irradiation. Irradiation at the confluent stage enhanced accumulation of type I collagen normalized to the DNA content. Irradiation at all stages down-regulated the expression of osteocalcin, but the levels of osteopontin and osteonectin mRNAs were unchanged from the control level. After irradiation at the later stages, the time-dependent increase in alkaline phosphatase activity per cell exceeded that in the control cells. The localization of alkaline phosphatase-positive cells was concordant with that of calcification. In addition, the quality of the calcium deposits was found to be similar to that in control cells as determined by energy dispersive spectrometry and the ratio of calcium to phosphorus, even if the cells were not exactly the same morphologically. The changes in phenotypic expression observed here are closely related to the enhancement of calcification observed in a previous study.

Epstein-Barr virus infection and response to radiotherapy in squamous cell carcinoma of the oral cavity

We have retrospectively investigated the presence of Epstein-Barr virus (EBV) DNA in 45 cases of squamous cell carcinomas (SCCs) of the oral cavity using polymerase chain reaction (PCR). We analyzed the association between EBV infection and the clinicopathological characteristics, tumor response to radiotherapy, or prognosis to determine the clinical significance of EBV. EBV DNA was detected in 29 cases (64.4%) of SCCs. No significant differences were observed between the presence or absence of EBV. Our results indicate that EBV infection is not related to tumor response to radiotherapy, or the prognosis of the patients.

Effects of X irradiation on metabolism of proteoglycans.

The effects of X irradiation on matrix formation by growth-plate and articular chondrocytes, as reflected by metabolism of proteoglycans and type II collagen, were examined in a rabbit chondrocyte culture system. Irradiation with 1 to 10 Gy selectively inhibited synthesis of proteoglycans (incorporation of [35S]sulfate) depending on the stage of differentiation of the irradiated cells; however, synthesis of type II collagen was not affected. Irradiation of an immature culture, in which chondrocytes had just reached confluence, suppressed incorporation of [35S]sulfate into the glycosaminoglycan, 10 Gy inducing approximately 45-50% inhibition. In contrast, the irradiation of mature cultures, in which chondrocytes had already secreted extensive cartilage matrix, did not affect the rate of synthesis of proteoglycans (incorporation of [35S]sulfate). We also found that here irradiation stimulated the degradation of proteoglycans, but with the effect differing in growth-plate chondrocytes and articular chondrocytes. In growth-plate chondrocytes, cleavage from a site close to the G1 globular domain induced by 10 Gy enhanced the release of 35S-labeled proteoglycans into the medium, whereas in articular chondrocytes, irradiation had only marginal effects on the release of 35S-labeled proteoglycans. Our results show that irradiation with 1-10 Gy impaired proteoglycan metabolism in cartilage, with differing effects according to the stage of cell differentiation and the type of chondrocyte.