Isamu Kashima

Basic helix-loop-helix transcription factor DEC1 negatively regulates cyclin D1.

DEC1 (also known as Stra13/Bhlhb2/Sharp2) and DEC2 (also known as Bhlhb3/Sharp1) are two paralogous basic helix‐loop‐helix (bHLH) transcriptional regulators which exhibit a robust circadian gene expression pattern in the suprachiasmatic nucleus (SCN) and in peripheral organs. DEC1 has been suggested to play key roles in mammalian cell differentiation, the cell cycle and circadian regulation, hypoxia response, and carcinogenesis. Here we show that DEC1 overexpression exhibits delayed wound healing and reduces cell proliferation, migration, and invasion. DEC1 strongly repressed the promoter activity of cyclin D1. We further identify a possible DEC‐response element in the cyclin D1 promoter region, and confirmed the direct binding of DEC1 to that element. Forced expression of DEC1 efficiently repressed the cyclin D1 promoter and expression. Our clinical data provide the first evidence that there is a strong inverse correlation between DEC1 and cyclin D1 expression in oral cancer, and DEC1 expression significantly correlated with clinicopathological parameters. We suggest that radiation‐induced DEC1 overexpression and Akt phosphorylation in cancer cells are mediated via PI‐3K signalling. Overexpression of DEC1 activates the PI‐3K/Akt signalling pathway through reactive oxygen species (ROS). Copyright

Computed panoramic tomography with scanning laser-stimulated luminescence

A new imaging system for the dental field that combines recent advances in both the electronics and computer technologies was developed. It is a panoramic tomography process based on the newly developed laser-scan system and an imaging system featuring (1) clear images with abundant diagnostic information and wide latitude; (2) the possibility of new diagnostic methods through image-information processing; and (3) reduction of exposure to a minimum.

Intraoral computed radiography using the Fuji computed radiography imaging plate : correlation between image quality and reading condition

The quality of images obtained by a new method of intraoral computed radiography using three types of imaging plates and a drum scanner designed exclusively for use with an imaging plate was investigated. The aperture size for reading of radiographic data from the imaging plate and for film recording was 50, 100, or 150 microns 2. The results indicated that high resolution type imaging plate for mammography produced the best image quality. For each imaging plate, it was also found that the image quality improved as the aperture size was decreased. However, the high resolution type IP even at the aperture size of 100 microns 2 showed diagnostic accuracy as high as the image processing of conventional periapical radiographs. This finding suggests that this new imaging system using an imaging plate at the reading and recording aperture size 100 microns 2 has promise for use in intraoral radiography.

Structuring of parameters for assessing vertebral bone strength by star volume analysis using a morphological filter

Abstract Based on the relationship between bone strength, trabecular skeletal structure, and bone mineral density (BMD), structure parameters for assessing vertebral bone strength were studied using 18 cancellous bone blocks from the third lumbar vertebra of elderly persons. The trabecular bone pattern of each bone block was binarized into a trabecular skeletal pattern by computed radiography (CR) using a morphological filter. The binarized trabecular skeletal pattern was quantified into a trabecular skeletal pixel percentage (SKP; volume parameter of the trabecular skeletal signal component) and trabecular skeletal star volume (Vt; connection parameter of the trabecular skeletal structure) by star volume analysis. Then, the BMD and elasticity of each bone block were measured by dual X-ray absorptiometry and mechanical tests to determine the correlation between SKP and Vt. In the present study, no significant correlations were observed between BMD and elasticity. Elasticity differed greatly between some bone blocks even though BMD was essentially the same. Grid-like skeletal patterns consisting of vertical and horizontal continuous lines showed higher elasticity. SKP showed higher correlations with elasticity than BMD in subset (n = 2–7) and sumset images, although the fluctuation range was narrow. Meanwhile, Vt showed higher correlations with elasticity than SKP in subset (n = 1–6) and sumset images. Vt showed stronger correlations with elasticity than SKP. This fact indicates that strong relationships exist between the connectivity of trabecular skeletal structure and bone strength. Because the SKP–BMD and Vt–BMD correlations are weak, the influences exerted by SKP and Vt seem to be independent of the influence of BMD on the bone strength of vertebra obtained from persons with advanced age. These results indicate that SKP and Vt obtained by star volume analysis using a morphological filter are effective as structure parameters for analyzing the bone quality of lumbar vertebra.

PROLONGED ENDOCHONDRAL BONE HEALING IN SENESCENCE IS SHORTENED BY LOW-INTENSITY PULSED ULTRASOUND IN A MANNER DEPENDENT ON COX-2

To test whether mechanical loading produces faster healing in aged mice, fractured femurs of aged 1-year-old mice were subjected to low-intensity pulsed ultrasound (LIPUS), a treatment that is routinely used to help heal fractures in humans. Cyclooxygenase-2 knockout mice (COX-2(-/-)), which lack an immediate early mediator of mechanical stimulation, were also studied by histochemistry, microcomputed tomography and quantitative polymerase chain reaction to determine the role of COX-2. The healing in the aged COX-2(-/-) mice is slow during the endochondral bone remodeling (>30 d), a period generally prolonged in senescence. For aged wild-type mice, LIPUS halved the endochondral phase to about 10 d, whereas that was not the case for aged COX-2(-/-) mice, which showed no apparent shortening of the prolonged endochondral-phase healing time. Injecting prostaglandin E(2) receptor agonists, however, rescued the COX-2(-/-) callus from insensitivity to LIPUS. In conclusion, COX-2 is a limiting factor in the delayed endochondral bone healing and is induced by LIPUS, which normalizes healing rate to the wild-type level.

Horizontal Condylar Path in Patients with Disk Displacement with Reduction

In 32 patients with disk displacement with reduction, the condylar path in the horizontal plane during opening and closing movements of the mandible were analyzed with a computerized axiograph. The horizontal condylar tracings during opening were divided into 15 types. There was no clear relationship between the types and clinical symptoms. The specific correspondence of the types were revealed between the right and left joint. In 21 of 32 patients, the condyle on one side deviated medially, while the contralateral condyle deviated laterally at maximum opening. In most of the patients showing medio-lateral condylar deviation at maximum opening, a straight condylar path was observed from the maximum opening to the position just before the closing click. In some of the patients, the type of horizontal condylar tracing during opening was related to the displacement pattern of the disk assessed by magnetic resonance imaging (MRI).

Skeletal pattern extraction of bone trabeculae using mathematical morphology

Studies of morphology in extracting skeletal paterns of spiculae in mammograms served as a theoretical framework. Using studies of morphology in extraction of skeletal patterns of spiculae in mammograms as a theoretical framework, we applied a morphological filter (a combination of a skeleton operation and a single structuring element) to the extraction of skeletal patterns of bone trabeculae on computed radiographic (CR) images. Then, the comparison of the original images with the extracted skeletal patterns and the relationship between the sequence number(n) of the operation and the extracted skeletal patterns was reviewed. The comparison showed that skeletal patterns of the original image were extracted as binary images when using a morphological filter, and that, when n was small (n=0 or 1), skeletal patterns of both fine and wider bone trabeculae were extracted. Furthermore, with an increase in n, skeletal patterns of fine bone were eliminated, and only wider skeletal patterns were extracted selectively. These findings suggest that development of a suitable morphological filter to extract the skeletal patterns of bone trabeculae may be an effective supplement for computer aided diagnosis of medical images (CADM) in the support of adequate diagnosis of bone diseases.

Morphologically extracted trabecular skeleton superimposed upon digital radiograph structure

Abstract: The purpose of this study was to employ a morphological filter to digital X-ray images to extract the morphology of trabecular structures in a clearly understandable visual format. This study compares the trabecular skeleton extracted by a morphological filter to the original digital radiographic image by superimposing the images. A morphological filter (a combination of a single structuring element and a skeleton operation) based on a mathematical morphology theory was used to extract the skeletal pattern of trabecular bone from a digital X-ray image of a human femoral neck. Subset images with different operation numbers (n = 1, n = 2) were obtained, and then each image was superimposed on the original digital radiographic image using the superimpose function of a workstation. The extracted trabecular skeleton pattern was fairly consistent with the trabecular structure seen on the digital image according to the opinion of seven dentomaxillofacial radiologists. In their opinion, the majority of the structural elements were reproduced on the extracted skeleton. However, accurate skeleton elements were not extracted in the region of dense trabecular structure. The morphological filter was able to extract a large portion of the bone trabecular structure as a binary skeletal pattern image from trabecular bone on digital X-ray image, but more work is needed to improve the assessment of dense trabeculae.

Osteoarthritic Changes of the Patellofemoral Joint in STR/OrtCrlj Mice Are the Earliest Detectable Changes and may be Caused by Internal Tibial Torsion

STR/ort mice develop a naturally occurring osteoarthritis (OA) of the knee joints. However, the evaluation of early OA changes has been difficult due to variability caused by gender, individual differences, and differences between the right and left lower limbs. The objective of this study was to analyze the variability of the early OA changes with age in STR/ort mice and to identify the cause of onset. A total of 115 STR/OrtCrlj mice aged 10–45 weeks were examined. In addition to conventional radiological and histological evaluation of the knee joints, histological sections were used to examine the patellofemoral, femorotibial, and growth plate cartilage under similar conditions. A morphological evaluation of tibiae, including micro-3-dimensional computed tomography, was performed. Radiological evaluation showed OA changes in the joints of mice over 35 weeks old and histological evaluation showed early OA changes in the femorotibial joints of mice over 26 weeks old. However, these changes were not common in all individuals. In contrast, most common and reproducible OA changes were observed in the bilateral patellofemoral joints of all individuals, and even in subjects ranging from 10 to 20 weeks of age. Morphological evaluations also demonstrated an abnormal tibial internal torsion that increased with age and was associated with medial patellar dislocation. In conclusion, the earliest histological OA change was observed in the patellofemoral joint prior to similar observations in the femorotibial joint. Internal tibial torsion may be a cause of OA in the patellofemoral joints, which leads to the development of medial femorotibial OA.

Diagnostic imaging of diseases affecting the mandible with the use of computed panoramic radiography.

Computed panoramic radiography was performed on patients with bone cyst, osteomyelitis, gingival cancer, and fibrous dysplasia, respectively, to determine the best imaging procedure for disease processes affecting the mandible. Gradational enhancement images for detection of density changes and frequency enhancement images for detecting changes in the margin and texture were effective in aiding the diagnosis of diseases of the mandible with the use of computed panoramic radiography.