Prediction of Perceived Steering Wheel Operation Force by Muscle Activity.

Humans feel forces or weights while grasping and manipulating an object. There is a difference between the physical and perceived forces because the physical characteristics of an object and/or human psychophysical characteristics affect perceived force. Sense of effort plays an important role in deciding the movement made by humans. In this study, we propose a computational method to predict the perceived force by evaluating the muscle activity as a function of effort in the operation of a steering wheel based on a 3D-musculoskeletal model simulation. We found that the perceived-force characteristics depend on the driving posture, though the applied force is the same. We evaluated the results, and showed that the mean of the absolute error is 1.78 N for the experiments conducted on four different vehicles in commercially available.

Biological activities of the homologous loop regions in the laminin α chain LG modules.

Each laminin α chain (α1-α5 chains) has chain-specific diverse biological functions. The C-terminal globular domain of the α chain consists of five laminin-like globular (LG1-5) modules and plays a critical role in biological activities. The LG modules consist of a 14-stranded ß-sheet (A-N) sandwich structure. Previously, we described the chain-specific biological activities of the loop regions between the E and F strands in the LG4 modules using five homologous peptides (G4EF1-G4EF5). Here, we further analyze the biological activities of the E-F strands loop regions in the rest of LG modules. We designed 20 homologous peptides (approximately 20 amino acid length), and 17 soluble peptides were used for the cell attachment assay. Thirteen peptides promoted cell attachment activity with different cell morphologies. Cell attachment to peptides G1EF1, G1EF2, G2EF1, G3EF4, and G5EF4 was inhibited by heparin, and peptides G1EF1, G1EF2, and G2EF1 specifically bound to syndecan-overexpressing cells. Cell attachment to peptides G2EF3, G3EF1, G3EF3, G5EF1, G5EF3, and G5EF5 was inhibited EDTA. Further, cell attachment to peptides G3EF3, G5EF1, and G5EF5 was inhibited by both anti-integrin α2 and ß1 antibodies, whereas cell attachment to peptide G5EF3 was inhibited by only anti-integrin ß1 antibody. Cell attachment to peptides G1EF4, G3EF4, and G5EF4 was inhibited by both heparin and EDTA and was not inhibited by anti-integrin antibodies. The active peptide sequence alignments suggest that the syndecan-binding peptides contain a "basic amino acid (BAA)-Gly-BAA" motif in the middle of the molecule and that the integrin-binding peptides contain an "acidic amino acid (AAA)"-Gly-BAA motif. Core-switched peptide analyses suggested that the "BAA-Gly-BAA" motif is critical for binding to syndecans and that the "AAA-Gly-BAA" motif has potential to recognize integrins. These findings are useful for understanding chain-specific biological activities of laminins and to evaluate receptor-specific binding mechanisms.

A novel PET scanner with semiconductor detectors may improve diagnostic accuracy in the metastatic survey of head and neck cancer patients.

OBJECTIVES: Our research group developed new PET scanner with semiconductor detectors for high spatial resolution with low scatter noise. On head and neck cancer (HNC) surgery, FDG-PET may often provide false-positive findings in cervical node involvements. Accordingly, we assessed diagnostic accuracy using this new scanner in the HNC patients as compared with the conventional lutetium oxyorthosilicate (LSO) PET. METHODS: We prospectively studied FDG imaging in 35 HNC patients by both semiconductor PET and LSO-PET. At 60 min after (18)F-FDG injection, two PET scans were obtained using both scanners consecutively and in random order. Two nuclear medicine specialists scored FDG abnormalities using 5 point scale system for receiver operating characteristic (ROC) curve analysis. RESULTS: 63 suspected of metastatic or recurrent lesions were evaluated and correlated by the final confirmation by pathological findings or clinical courses (malignant 26/benign 37). Semiconductor PET showed sensitivity of 92.3 % (24/26), specificity of 51.4 % (19/37), and accuracy of 68.2 % (43/63), while LSO-PET showed sensitivity of 84.6 % (22/26), specificity of 16.2 %(6/37), and accuracy of 44.4 % (28/63), respectively. Especially, semiconductor PET accurately diagnosed as true negative in the 13 of 14 lesions only detected by LSO-PET. ROC analyses revealed the diagnostic superiority of semiconductor PET from location of- and area under curve particularly in the study of small (≤10 mm) lesions. CONCLUSION: A new novel semiconductor PET scanner can increase diagnostic accuracy with reduction in false positive findings in the HNC patients mainly due to higher spatial resolution and lower noise than the LSO-PET. This new technology can lead to more accurate diagnosis and the more optimal therapeutic tactics in head and neck surgery.

Regional differences in the components of luminal water from rat gastrointestinal tract and comparison with other species.

PURPOSE: The bile acids, phospholipids, inorganic ions, and pH in luminal fluid are very important factors for the dissolution and oral absorption of solid drugs. In this study, we evaluated the regional differences in these factors in the rat GI tract. The solubility of griseofulvin, a poorly water-soluble drug, in the luminal fluid in each segment was also measured. In addition, the data from rats were compared with those from other species published previously to evaluate the species differences in the composition of luminal fluid. METHODS: Rat abdomen was opened and residual water was sampled from each region of GI tract to measure the various components concentrations. RESULTS: The total bile acid and phospholipid concentrations were much higher in the lower jejunum and upper jejunum, respectively, than in the other regions. The solubilities of griseofulvin in the lower jejunal fluid (153-260 ug/mL) were about 1.5-2 times higher than those in the upper jejunal fluid (99-146 ug/mL). The regional differences in inorganic ions and pH were also observed. As for species differences, the total bile acid and phospholipid concentration in rats GI tract were much higher than those of dogs and humans. CONCLUSION: These informations about the regional differences and species differences of the components in the GI fluid should be very useful to consider dissolution and oral absorption of solid drugs.

Effect of surface roughness of titanium dental implant placed under periosteum on gene expression of bone morphogenic markers in rat.

Various bone matrix proteins are produced during the process of osteogenesis. Many previous studies suggested that the topography of an implant surface might affect the expression of osteoblast-mediated cytokines. However, these earlier studies were performed using in vitro cell culture. This study investigated the influence of the surface topography of a titanium implant placed under the periosteum on the gene expression of bone morphogenic markers in rat. Six custom-made implants with a rough upper surface and 6 custom-made implants with a smooth machined upper surface were placed subcrestally with the upper surface facing up in the femurs of 6 adult male rats. Five rats were sacrificed 7 days after the implant placement, and the periosteum above the embedded implant was obtained and analyzed by quantitative real-time RT-PCR for the target genes: alkaline phosphatase (ALP), bone sialoprotein (BSP) and osteocalcin (OCN). The other rat was sacrificed at day 7, and both implants and the surrounding tissue were embedded in paraffin. For light microscopic observations, paraffin sections were stained with toluidine blue. Gene expression of ALP, BSP and OCN at the rough surface implant was significantly higher than that at the smooth machined surface implant. At day 7, both types of implant were covered with soft tissue, but a lower number of cells stained with toluidine blue was observed on the machined surface compared with on the rough surface. It is considered that rough surfaces may stimulate osteoblasts, and that ALP activity is increased indirectly. Furthermore, the two other markers were also increased by the rough surface in vivo, and different distributions of cellular and extracellular components on the upper surface of the implants were observed at day 7. These results suggest that a rough surface implant under the periosteum promotes higher gene expression of ALP, BSP and OCN in rat.

[Clinical analysis of malignant submandibular tumor].

The 14 cases of malignant submandibular tumor whose treatment outcome we analyzed between 1989 and 2008 included 5 of adenoid cystic carcinoma, 3 of squamous cell carcinoma, 2 each of mucoepidermoid carcinoma, and carcinoma ex pleomorphic adenoma, and 1 each of carcinosarcoma and large-cell carcinoma. One subject was diagnosed with T1, 7 with T2, 4 with T3, and 2 with T4. Lymph node involvement occurred in 5, -1 with N1 and 4 with N2. None had distant metastasis on the first visit. Seven were treated by surgery alone, 3 by surgery followed by radiotherapy, 2 by surgery followed by radio-and chemotherapy, and 1 by optimized supportive care. The surgical resection area was decided by tumor extension. Neck dissection was done in 9. Overall 5-year survival for all cases based on the Kaplan-Meier method was 57%. All with carcinoma ex pleomorphic adenoma, carcinosarcoma, or large-cell carcinoma remain alive. For those with adenoid cystic carcinoma 5-year survival is 80%, with mucoepidermoid carcinoma 50%, with squamous cell carcinoma 0%, and with carcinosarcoma 0%, respectively. The 5-year survival for stage I subjects was 100%, for stage II 83%, for stage III 50%, and for stage IV 0%. Surgical resection and postoperative radiotherapy were done in cases of minimal extraglandular extension or microscopically positive margins, with satisfactory results. Treatment efficacy for high-grade and advanced stage, however, requires more improvement.

Cell adhesive peptide screening of the mouse laminin α1 chain G domain.

Cell adhesive peptides have been widely applied for therapeutic drugs, drug delivery systems, and biomaterials. Previously, we identified various cell adhesive sequences in the G domains of four laminin α chains (α2-α5) by the systematic soluble peptide screening. We also identified five cell-binding sequences in the laminin α1 chain G domain using synthetic peptide-polystyrene beads. Here, we re-screened cell adhesive peptides in the laminin α1 chain G domain by the systematic soluble peptides screening. The 110 soluble peptides were evaluated for their cell adhesive activities using human fibrosarcoma HT1080 cells and human dermal fibroblasts. Fourteen peptides were newly identified as a cell adhesive. Additionally, four peptides (AG22: SSFHFDGSGYAM, AG42: TFDLLRNSYGVRK, AG76: HQNQMDYATLQLQ, AG86: LGGLPSHYRARNI) promoted integrin-mediated cell adhesion. Further, neurite outgrowth activity with rat pheochromocytoma PC12 cells was evaluated and two peptides (AG20: SIGLWNYIEREGK, AG26: SPNGLLFYLASNG) were newly identified for neurite outgrowth activity. These results suggested that the systematic soluble peptides screening approach is an accurate and powerful strategy for finding biologically active sequences. The active sequences newly identified here could be involved in the biological functions of this domain. The active peptides are useful for evaluating molecular mechanisms of laminin-receptor interactions and for developing cell adhesive biomaterials.

The ERK-RSK1 activation by growth factors at G2 phase delays cell cycle progression and reduces mitotic aberrations.

Growth factors accelerate G0 to S progression in the cell cycle, however, the roles of growth factors in other cell cycle phases are largely unknown. Here, we show that treatment of HeLa cells with hepatocyte growth factor (HGF) at G2 phase induced the G2/M transition delay as evidenced by FACS analysis as well as by mitotic index and time-lapse analyses. Growth factors such as epidermal growth factor (EGF) and fibroblast growth factor (FGF) also induced G2/M transition delay like HGF. HGF treatment at G2 phase causes a delayed activation of cyclin B1-associated kinase and a diminished nuclear translocation of cyclin B1. Either U0126, a MAPK kinase (MEK) inhibitor, or kinase-dead mutant of ribosomal S6 kinase (RSK) abolished the delay. Additionally, knockdown of RSK1, but not RSK2, with siRNA abrogated the delay, indicating that the extracellular-regulated protein kinase (ERK)-RSK1 mediates the HGF-induced delay. We further found that the delay in G2/M transition of cells expressing oncogenic HGF receptor, M1268T, was abolished by RSK1 knockdown. Intriguingly, we observed that HGF induced chromosomal segregation defects, and depletion of RSK1, but not RSK2, aggravated these chromosomal aberrations. Taken together, the ERK-RSK1 activation by growth factors delays G2/M transition and this might be required to maintain genomic integrity during growth factor stimulation.

Morphological changes in the internal structure of the articular eminence of the temporal bone during growth from deciduous to early mixed dentition.

Previously, bio-mechanical studies on the temporomandibular joint have concentrated mainly on the mandibular condyle while the articular eminence has been largely overlooked. Furthermore, research on the mechanical properties of bone using finite element analysis has focused on the cortical bone in preference to cancellous bone. In this study morphorogical changes in the internal structure of the articular eminence as related to child growth were examined using Micro-CT. Morphometric analysis of samples of cancellous bone representing both deciduous and early mixed dentitions showed an increase in the bone volume fraction and trabecular thickness in the early mixed dentition, and finite element analysis indicated directional transmission of stress as well. These results suggest that the morphology of the trabecular bone was altered to adapt to the functional growth progressed from the deciduous to the early mixed dentition.

The neurofibromatosis type 1 gene product neurofibromin enhances cell motility by regulating actin filament dynamics via the Rho-ROCK-LIMK2-cofilin pathway.

Neurofibromin is a neurofibromatosis type 1 (NF1) tumor suppressor gene product with a domain that acts as a GTPase-activating protein and functions, in part, as a negative regulator of Ras. Loss of neurofibromin expression in NF1 patients is associated with elevated Ras activity and increased cell proliferation, predisposing to a variety of tumors of the peripheral and central nervous systems. We show here, using the small interfering RNA (siRNA) technique, that neurofibromin dynamically regulates actin cytoskeletal reorganization, followed by enhanced cell motility and gross cell aggregation in Matrigel matrix. NF1 siRNA induces characteristic morphological changes, such as excessive actin stress fiber formation, with elevated negative phosphorylation levels of cofilin, which regulates actin cytoskeletal reorganization by depolymerizing and severing actin filaments. We found that the elevated phosphorylation of cofilin in neurofibromin-depleted cells is promoted by activation of a Rho-ROCK-LIMK2 pathway, which requires Ras activation but is not transduced through three major Ras-mediated downstream pathways via Raf, phosphatidylinositol 3-kinase, and RalGEF. In addition, the exogenous expression of the NF1-GTPase-activating protein-related domain suppressed the NF1 siRNA-induced phenotypes. Neurofibromin was demonstrated to play a significant role in the machinery regulating cell proliferation and in actin cytoskeletal reorganization, which affects cell motility and adhesion. These findings may explain, in part, the mechanism of multiple neurofibroma formation in NF1 patients.

The tumor suppressor WARTS activates the Omi / HtrA2-dependent pathway of cell death.

Drosophila tumor suppressor WARTS (Wts) is an evolutionally conserved serine / threonine kinase and participates in a signaling complex that regulates both proliferation and apoptosis to ensure the proper size and shape of the fly. Human counterparts of this complex have been found to be frequently downregulated or mutated in cancers. WARTS, a human homolog of Wts, is also known as tumor suppressor and mitotic regulator, but its molecular implications in tumorigenesis are still obscure. Here, we show that WARTS binds via its C-terminus to the PDZ domain of a proapoptotic serine protease Omi / HtrA2. Depletion of WARTS inhibited Omi / HtrA2-mediated cell death, whereas overexpression of WARTS promoted this process. Furthermore, WARTS can enhance the protease activity of Omi / HtrA2 both in vivo and in vitro. Activation of Omi / HtrA2-mediated cell death is thus a potential mechanism for the tumor suppressive activity of WARTS.

Tumor suppressor WARTS ensures genomic integrity by regulating both mitotic progression and G1 tetraploidy checkpoint function.

Defects in chromosomes or mitotic spindles activate the spindle checkpoint, resulting in cell cycle arrest at prometaphase. The prolonged activation of spindle checkpoint generally leads to mitotic exit without segregation after a transient mitotic arrest and the consequent formation of tetraploid G(1) cells. These tetraploid cells are usually blocked to enter the subsequent S phase by the activation of p53/pRb pathway, which is referred to as the G(1) tetraploidy checkpoint. A human homologue of the Drosophila warts tumor suppressor, WARTS, is an evolutionarily conserved serine-threonine kinase and implicated in development of human tumors. We previously showed that WARTS plays a crucial role in controlling mitotic progression by forming a regulatory complex with zyxin, a regulator of actin filament assembly, on mitotic apparatus. However, when WARTS is activated during cell cycle and how the loss of WARTS function leads to tumorigenesis have not been elucidated. Here we show that WARTS is activated during mitosis in mammalian cells, and that overexpression of a kinase-inactive WARTS in Rat1 fibroblasts significantly induced mitotic delay. This delay resulted from prolonged activation of the spindle assembly checkpoint and was frequently followed by mitotic slippage and the development of tetraploidy. The resulting tetraploid cells then abrogated the G(1) tetraploidy checkpoint and entered S phase to achieve a DNA content of 8N. This impairment of G(1) tetraploidy checkpoint was caused as a consequence of failure to induce p53 expression by expressing a kinase-inactive WARTS. WARTS thus plays a critical role in maintenance of ploidy through its actions in both mitotic progression and the G(1) tetraploidy checkpoint.

Aurora-A kinase maintains the fidelity of early and late mitotic events in HeLa cells.

Aurora-A, a member of the Aurora/Ipl1-related kinase family, is overexpressed in various types of cancer and considered to play critical roles in tumorigenesis. To better understand the pathological effect of Aurora-A activation, it is first necessary to elucidate the physiological functions of Aurora-A. Here, we have investigated the roles of Aurora-A in mitotic progression with the small interfering RNA, antibody microinjection, and time lapse microscopy using human cells. We demonstrated that suppression of Aurora-A by small interfering RNA caused multiple events to fail in mitosis, such as incorrect separation of centriole pairs, misalignment of chromosomes on the metaphase plate, and incomplete cytokinesis. Antibody microinjection of Aurora-A into late G2 cells induced dose-dependent failure in separation of centriole pairs at prophase, indicating that Aurora-A is essential for proper separation of centriole pairs. When we injected anti-Aurora-A antibodies into prometaphase cells that had separated their centriole pairs, chromosomes were severely misaligned on the metaphase plate, indicating that Aurora-A is required for proper movement of chromosomes on the metaphase plate. Furthermore, inhibition of Aurora-A at metaphase by microinjected antibodies prevented cells from completing cytokinesis, suggesting that Aurora-A also has important functions in late mitosis. These results strongly suggest that Aurora-A is essential for many crucial events during mitosis and that the phosphorylation of a series of substrates by Aurora-A at different stages of mitosis may promote diverse critical events in mitosis to maintain chromosome integrity in human cells.

[Dynamics of bone by mechanical load].

The jaw bone receive complicated forces not only through the muscles, but through the teeth directly. Therefore, it is thought that the morphology of the trabecular bone in jaw is greatly effected by the teeth. The structures of the trabecular bone are constructed in order to support the teeth. With loss of the teeth, both width and volume of the trabecular bone are reduced and the trabecular bone run in the irregular course. Consequently, these findings suggested that mechanical forces change to the structures of trabeculare in jaw bone.

[Oral function and morphology of jaw bone].

It is said that the morphology of the jaw bone is greatly effected by the loss of teeth compared with the aging. To know the morphological changes of the mandible and maxilla with loss of the teeth is essential to reconstruct oral function. Therefore, we compared the edentulous jaw bone with the dentulous one. It is observed that the height of the maxilla and mandible is rapidly shortened in edentulous jaw bone. Based on these findings, it is suggested that maintenance of the intact teeth is important to keep the normal morphology of the jaw bone.

WARTS tumor suppressor is phosphorylated by Cdc2/cyclin B at spindle poles during mitosis.

Identification of physiological substrates for Cdc2/cyclin B is crucial for understanding the functional link between mitotic events and Cdc2/cyclin B activation. A human homologue of the Drosophila warts tumor suppressor, termed WARTS, is a serine/threonine kinase and a dynamic component of the mitotic apparatus. We have found that Cdc2/cyclin B forms a complex with a fraction of WARTS in the centrosome and phosphorylates the Ser613 site of WARTS during mitosis. Immunocytochemical analysis has shown that the S613-phosphorylated WARTS appears in the spindle poles at prometaphase and disappears at telophase. Our findings suggest that Cdc/cyclin B regulates functions of WARTS on the mitotic apparatus.