Biomedical subjects

Shigeru Soshi

Publications and source records attributed to Shigeru Soshi.

3 recordsLinked to original sources

PubMed2006

Anatomical considerations for cervical pedicle screw insertion: the use of multiplanar computerized tomography reconstruction measurements.

OBJECT: The purpose of this study was to evaluate the linear and angular parameters of the vertebral body (VB) required for cervical pedicle screw (CPS) insertion by using multiplanar computerized tomography (CT) reconstructions. METHODS: Three hundred fifteen vertebrae from C-3 to C-7 in 63 patients were studied. Pedicle dimensions such as pedicle transverse angle (PTA), pedicle sagittal angle (PSA), and pedicle outer width (POW) were measured on axial CT reconstructions, as were linear parameters including the lateral mass thickness (LMT), the anteroposterior (AP) and mediolateral distances between spinal canal and transverse foramen, and spinal canal longitudinal and transverse diameter. In addition, the correlations between PTA and other parameters were calculated using univariate linear regression analysis. The overall mean LMT ranged from 10.7 to 12.6 mm. The smallest mean AP spinal canal-transverse foramen distance was found at C-7 (1.1 mm),whereas the largest mean distance was at C-4 (3.1 mm). The smallest mean mediolateral spinal canal-transverse foramen distance was found at C-4 (1.2 mm), whereas the largest mean distance was at C-7 (4.7 mm). There were significant intergroup differences between male and female patients except for PTA and spinal canal longitudinal diameter. The PTA had a direct linear correlation with AP and mediolateral spinal canal-transverse foramen distances. The largest Pearson coefficient was 0.71 between the PTA and AP spinal canal-transverse foramen distance and the inverse one was -0.73 between the PTA and mediolateral spinal canal-transverse foramen distance. CONCLUSIONS: Analysis of the data obtained in this study suggests that not only pedicle dimensions but also linear and angular parameters of the VB can be useful data when inserting a CPS.

Adolescent↗

PubMed2004

Intensity-related differences in collagen post-translational modification in MC3T3-E1 osteoblasts after exposure to low- and high-intensity pulsed ultrasound.

Low-intensity pulsed ultrasound (LIPUS) has distinct effects on biologic mineralization at intensities of <100 mW/cm2. Intensity-dependent differences in the pattern of accelerated mineralization may be due to different alterations in regulation of collagenous matrix formation. However, little is known about the influence of LIPUS on collagen metabolism in the context of mineralization processes. Therefore, we attempted to evaluate differential effects of two intensities of pulsed ultrasound (30 vs. 120 mW/cm2) on collagen post-translational modification and mineralization in osteoblastic MC3T3-E1 cells. Murine osteoblastic MC3T3-E1 cells were exposed to pulsed ultrasound (1.5-MHz, 200-ms burst sine wave at 1.0-kHz frequency, either 30 or 120 mW/cm2 SATA, for 20 min/day from Day 14 to Day 35 postconfluence). Expression patterns of lysyl oxidase (LO), procollagen-lysine, 2-oxyglutarate, 5-dioxigenase 1 (PLOD1, LH1), and 2 (PLOD2, LH2) was examined using quantitative PCR. Quantitative analysis of reducible immature cross-links (dihydroxylysinonorleucine, hydroxylysinonorleucine, and lysinonorleucine) and nonreducible mature cross-links (pyridinoline and deoxypyridinoline) as well as analysis of the maturation of immature to mature cross-links were performed. Exposure to 30 mW/cm2 LIPUS upregulated LH2 mRNA expression and enzyme activity compared to controls. It was associated with increased relative amounts of telopeptidyl hydroxylysine (Hyl)-derived cross-links beginning on Day 14, upregulated LO mRNA expression, increased total reducible and nonreducible cross-links, and increased ratios of newly formed nonreducible to reducible cross-links. Similarities in the pattern of cross-link formation and calcium deposition in matrices between 30 mW/cm2 LIPUS-treated MC3T3-E1 cultures and bone suggest that 30 mW/cm2 LIPUS may promote the maturation of collagenous matrix as a scaffold for calcification. In contrast, exposure to 120 mW/cm2 ultrasound increased calcium accumulation compared to control at Day 35, but increases were delayed until Day 25. No differences in the extent and pattern of cross-links were observed compared to controls. These results suggest that the promotion of mineralization induced by 120 mW/cm2 may be attributed to other factors involved in mineralization process rather than cross-link pattern. Our results demonstrated the existence of differential effects of lower versus higher intensities of ultrasound on mineralization processes in vitro.

3T3 Cells↗

PubMed2003

Effect of hyper- and microgravity on collagen post-translational controls of MC3T3-E1 osteoblasts.

UNLABELLED: We attempted to study the effects of microgravity (by clinostat) and hypergravity (using centrifugation) on collagen metabolism using murine MC3T3-E1 osteoblasts, especially focusing on collagen cross-link formation. We found that altered gravitational load affected the post-translational modification of collagen, particularly the collagen maturation pathway, through altered expression of enzymes involved in cross-link formation. INTRODUCTION: Gravitational loading plays important roles in the stimulation of differentiated osteoblast function and in the maintenance of skeletal tissues, whereas microgravity seems to result in osteopenia caused by impaired osteoblast differentiation. The aim of our study was to clarify the effects of altered gravitational environments on collagen metabolism, particularly the relationship between post-translational collagen quality and enzymes involved in cross-link formation, using murine osteoblastic MC3T3-E1 cells. MATERIALS AND METHODS: Cells were cultured under vector-averaged microgravity (1 x 10(-3) g) using a clinostat or under conventional centrifugation techniques to generate hypergravity (20 g and 40 g) for 72 h. We then examined the expression patterns of lysyl oxidase and the two lysyl hydroxylase isoforms telopeptidyl lysyl hydroxylase (TLH; procollagen-lysine, 2-oxyglutarate, 5-dioxigenase 2 [PLOD2]) and helical lysyl hydroxylase (HLH; [PLOD1]) by quantitative real time polymerase chain reaction (PCR) analysis. Quantitative analysis of reducible immature (dihydroxylysinonorleucine, hydroxylysinonorleucine, and lysinonorleucine) and nonreducible mature (pyridinoline and deoxypyridinoline) cross-links, and maturation rate analysis of immature to mature cross-links by conventional metabolic labeling using tritium lysine were also performed. RESULTS: Hypergravity upregulated both TLH mRNA expression and enzyme activity compared with stationary cultures, whereas microgravity stimulated both HLH mRNA expression and enzyme activity. These results were consistent with increased relative occupancy rates of telopeptidyl hydroxylysine-derived cross-links and helical hydroxylysine-derived forms observed under hypergravity and microgravity, respectively. Hypergravity stimulated not only lysyl oxidase mRNA expression but also increased enzyme activity and the sum of immature and mature cross-links. Furthermore, the conversion rate of immature cross-links to mature compounds was markedly increased under hypergravity but decreased under microgravity. CONCLUSION: Altered gravitational loading may affect the post-translational modification of collagen through altered expression of enzymes involved in cross-link formation. These observations may be important in elucidating the mechanisms of osteopenia during space flight.

3T3 Cells↗