Chikahiro Takita

Tacrolimus and cyclosporine A inhibit human osteoclast formation via targeting the calcineurin-dependent NFAT pathway and an activation pathway for c-jun or MITF in rheumatoid arthritis

In the present study, we aimed to determine whether tacrolimus (FK506) and cyclosporine A act directly on human osteoclast precursors obtained from patients with rheumatoid arthritis (RA) and influence monocyte–osteoclast differentiation induced by receptor activator of NF-κB ligand (RANKL) in vitro, the stage at which differentiation was affected and the manner in which tacrolimus or cyclosporine A affected the osteoclast signaling pathway. Peripheral blood mononuclear cells (PBMCs) were isolated from RA patients and cultured in the presence of RANKL and macrophage-colony stimulating factor (M-CSF). Tacrolimus or cyclosporine A was added to these cultures to determine the effect on the osteoclast differentiation. Osteoclast formation was determined by assessing the number of tartrate resistant acid phosphatase (TRAP) staining cells and measuring the extent of lacunar resorption. The expression of osteoclast transcription factors, such as TNF receptor-associated factor 6 (TRAF6), nuclear factor of activated T cells c1 (NFATc1), c-Fos, c-Jun, microphthalmia transcription factor (MITF) and PU.1 in mononuclear cells (MNCs) was assayed by quantitative reverse transcription-polymerase chain reaction. Addition of tacrolimus or cyclosporine A resulted in a decrease in the number of TRAP-positive multinucleated cells (TRAP+ MNCs) and a decrease in the extent of lacunar resorption pit formation as compared to the control cultures; thus, human monocyte–osteoclast differentiation was more effectively inhibited at the late stage and addition of tacrolimus or cyclosporine A resulted in a decrease in the mRNA expression of NFATc1, c-Jun, and MITF at the late stage. Our results suggest that tacrolimus or cyclosporine A acts directly on human osteoclast precursors in RA patients and exerts their immunosuppressive effects on human monocyte–osteoclast formation via targeting both the calcineurin-dependent NFAT pathway and activation pathway for c-Jun or MITF.

The effect of selective cyclooxygenase-2 inhibitor on human osteoclast precursors to influence osteoclastogenesis in vitro

The inducible prostaglandin synthesis enzyme, cyclooxygenase-2 (COX-2), is involved in bone resorption and osteoclastogenesis, and acts indirectly through prostaglandin E2 (PG E2) produced by osteoblastic cells. This study was undertaken to investigate whether celecoxib (a selective COX-2 inhibitor) has a direct effect on human osteoclast precursors to influence osteoclastogenesis in vitro. Human peripheral blood mononuclear cells (PBMCs) were cultured on glass coverslips and dentine slices with soluble receptor activator of NF-kB ligand (sRANKL) and macrophage colony stimulating factor (M-CSF). COX inhibitors including celecoxib were added to the cultures. Osteoclast formation was assessed as the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and the functional evidence of lacunar resorption pits on dentine slices was assessed. Celecoxib and indomethacin inhibited osteoclast formation and the extent of lacunar resorption in a dose-dependent manner, but the effect of indomethacin was less than that of celecoxib. Mofezolac affected neither the number of TRAP-positive MNCs nor the extent of lacunar resorption pits. These results indicate that celecoxib influences not only osteoclast formation through osteoblastic cells but also acts directly on circulating osteoclast precursors to influence human osteoclast differentiation. The effect of celecoxib on osteoclast precursors may be related to the COX-2 signal pathway.

Analysis of measured D-dimer levels for detection of deep venous thrombosis and pulmonary embolism after spinal surgery.

Study Design A retrospective clinical study. Objectives To show the prevalence of deep venous thrombosis (DVT) and pulmonary embolism (PE) after spinal surgery using a D-dimer assay followed by screening with computed tomographic (CT) pulmonary angiography and CT venography. Summary of Background Data A few studies on DVT development after spinal surgery have been reported. Methods A complete surveillance examination for DVT and PE was conducted in 88 patients who underwent spinal surgery [male patients, 48; female patients, 40; average age at operation, 62.4 y (range, 17 to 85 y)] through a D-dimer assay combined with CT pulmonary angiography and CT venography. The operation levels were the cervical spine (21 cases), the thoracic spine (16 cases), and the lumbar spine (51 cases). We adopted a D-dimer cut-off point of 10 &mgr;g/mL, and classified the patients into high D-dimer (HD; D-dimer level ≥10 &mgr;g/mL) and low D-dimer (LD; D-dimer level <10 &mgr;g/mL) groups. Results Nine (10.2%) patients showed D-dimer levels of ≥10 &mgr;g/mL (HD group); of these, 5 patients (5.7%) had DVT. Two (2.2%) of the 5 DVT patients had PE. DVT was evident in 1 (6.2%) of the 16 patients who underwent thoracic procedures and 4 (7.8%) of the 51 patients who underwent lumbar procedures. Statistical comparison between the HD (excluding 5 patients with DVT or PE) and LD groups showed a significant difference in intraoperative blood loss between the groups (P=0.02). Conclusions The D-dimer assay was useful in predicting DVT development. A D-dimer level of ≥10 &mgr;g/mL is considered to be a risk factor for thromboembolic disease after spinal surgery. False-positive cases of thromboembolic disease preclude the use of this assay as a stand-alone test for DVT diagnosis. CT venography and CT pulmonary angiography are recommended to confirm thromboembolic disease.

Morphological analysis of the cervical pedicles, lateral masses, and laminae in developmental canal stenosis.

Study Design. Retrospective cross-sectional study. Objective. This study aimed to elucidate the relationship between developmental spinal canal stenosis (DCS) and morphologic features in the cervical spine by comparing the features between DCS and nondevelopmental spinal canal stenosis (NDCS). Summary of Background Data. DCS is an important predisposing factor for cervical myelopathy. Further, various posterior cervical spinal instrumentations have been developed. However, no study has specifically addressed the cervical posterior morphology of DCS. Methods. A total of 52 consecutive patients underwent cervical spine computed tomography myelography. Axial images of the largest pedicle diameter were selected from C3 to C7 vertebrae and 260 images were analyzed. The following parameters were measured: spinal canal longitudinal diameter (SCLD), spinal canal transverse diameter, osseous spinal canal area, dural sac area, spinal cord area, pedicle outer width, pedicle axis length, pedicle transverse angulation, lateral mass longitudinal diameter, lateral mass transverse diameter, lamina outer width, and lamina axis length. The participants were classified into 2 groups: DCS group (SCLD <12 mm at any level) and NDCS group (SCLD ≧12 mm at all levels). Results. The mean osseous spinal canal area and dural sac area at C3–C5 in the DCS group were less than those in the NDCS group. The mean spinal cord area did not differ significantly at C3–C7 between the groups. The mean pedicle outer width at C6 and C7 in the DCS group was less than that in NDCS group. The mean lateral mass transverse diameter at C5 and mean lateral mass longitudinal diameter at C3, C5, and C6 in the DCS group were less than those in the NDCS group. Conclusion. Myelopathy is expected to progress in patients with DSC and these patients with severe neurologic symptoms may need cervical operation. However, posterior screw insertions should be considered more carefully than in NDCS patients.

Idiopathic Heterotopic Ossification Within the Tibial Nerve

Heterotopic ossification has been reported to occur following burns, musculoskeletal trauma, and tetanus and in association with metabolic and neurologic disorders. Heterotopic ossification is found most commonly in the muscles, and histopathologically identical lesions have been described in tendons, subcutaneous fat, ligaments, fasciae, aponeuroses, and joint capsules1. Heterotopic ossification can also cause clinically relevant peripheral nerve entrapment2-4. Heterotopic ossification or calcification within a peripheral nerve is a rare lesion and may arise in association with neurofibroma5, leprosy6, CREST syndrome (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia)7, diabetic neuropathy8-10, and chronic renal failure11. In a recent review of the literature, we found only two cases of idiopathic intraneural heterotopic ossification12,13. We describe here an unusual case of a painful ossifying lesion arising from the tibial nerve in a man. The radiographic and histopathologic findings were similar to those of myositis ossificans. A forty-two-year-old male truck driver had persistent discomfort in the right popliteal fossa for four months. Previously, he had been healthy and he had no history of trauma. He reported the gradual onset of severe pain and tenderness and had noticed swelling in the right popliteal fossa and calf with paresthesias and decreased sensation in the right leg. He was referred to our hospital in January 2000. Physical examination disclosed a hard, …

Analysis of the relationship between facet joint angle orientation and lumbar spine canal diameter with respect to the kinematics of the lumbar spinal unit.

Study Design Retrospective cross-sectional study. Objective This study aimed to elucidate the relationship among facet orientation, kinematics of a spinal unit, and change in lumbar spine canal diameter by using kinetic magnetic resonance imaging. Summary of Background Data Some studies have suggested an association between increased sagittally oriented facet angles and degenerative lumbar spondylolisthesis. However, no study has specifically addressed the association of facet orientation with the kinematics of a spinal unit and change in canal diameter. Methods Kinetic magnetic resonance imagings were performed with patients in flexion, neutral, and extension positions. Study subjects were classified into 6 groups—AA, BB, CC, AB (BA), BC (CB), and AC (CA)—on the basis of bilateral facet angles (A, narrow; B, normal; and C, wide) and disc and facet joint degeneration. A magnetic resonance imaging analyzer was used for anatomic measurements and for calculating changes in canal diameters and disc bulging as well as the lumbar spine kinematics. Results Osseous canal diameters were significantly smaller in the group AA than in the group BB, whereas they were significantly larger in the group CC than in the group BB. Canal diameter at the disc level was significantly smaller in the group AA than in the group BB in all 3 positions, whereas it was significantly larger in the group CC than in the group BB. Translational motion was significantly more in the group AA than in the group BB, whereas it was significantly lesser in the group CC than in the group BB. Conclusions We demonstrated the relationship among facet orientation, osseous canal diameter, kinematics of a spinal unit, and change in lumbar spine canal diameter. Patients with sagittally oriented facets had narrow osseous canals with mobility, whereas those with coronally oriented facets had stable and wider osseous canals. This finding is helpful in understanding the mechanism underlying lumbar spinal canal stenosis and degenerative spondylolisthesis.