Biomedical subjects

Tsutomu Kawano

Publications and source records attributed to Tsutomu Kawano.

8 recordsLinked to original sources

PubMed2006

Colony-stimulating factor-1 increases osteoclast intracellular pH and promotes survival via the electroneutral Na/HCO3 cotransporter NBCn1.

Colony-stimulating factor-1 (CSF-1) promotes the survival of osteoclasts, short-lived cells that resorb bone. Although a rise in intracellular pH (pH(i)) has been linked to inhibition of apoptosis, the effect of CSF-1 on pH(i) in osteoclasts has not been reported. The present study shows that, in the absence of CO(2)/HCO(3)(-), CSF-1 causes little change in osteoclast pH(i). In contrast, exposing these cells to CSF-1 in the presence of CO(2)/HCO(3)(-) causes a rapid and sustained cellular alkalinization. The CSF-1-induced rise in pH(i) is not blocked by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, an inhibitor of HCO(3)(-) transporters but is abolished by removing extracellular sodium. This inhibition profile is similar to that of the electroneutral Na/HCO(3) cotransporter NBCn1. By RT-PCR, NBCn1 transcripts are present in both osteoclasts and osteoclast-like cells (OCLs), and by immunoblotting, the protein is present in OCLs. Moreover, CSF-1 promotes osteoclast survival in the presence of CO(2)/HCO(3)(-) buffer but not in its absence. Preventing the activation of NBCn1 markedly attenuates the ability of CSF-1 to 1) block activation of caspase-8 and 2) prolong osteoclast survival. Inhibiting caspase-3 or caspase-8 in OCLs prolongs osteoclast survival to the same extent as does CSF-1. This study provides the first evidence that osteoclasts express a CSF-1-regulated Na/HCO(3) cotransporter, which may play a role in cell survival.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed2004

The oblique posterior femoral condylar radiographic view following total knee arthroplasty.

BACKGROUND: It is often difficult to evaluate the posterior aspects of the femoral condyles after total knee arthroplasty. We have developed an imaging technique involving the use of the oblique posterior condylar view for the evaluation of the posterior aspects of the femoral condyles. The purpose of the present study was to compare the efficacy of this view with that of the true-lateral view. METHODS: Three orthopaedic surgeons analyzed fifty-five sets of radiographs (consisting of oblique posterior condylar and true-lateral views) for patients who had undergone total knee arthroplasty. The accuracy and reproducibility of the oblique posterior condylar view for the detection of radiolucencies were compared with those of the true-lateral view. RESULTS: The oblique posterior condylar view was significantly better than the true-lateral view for the detection of radiolucencies of the posterior aspects of the femoral condyles (p < 0.0005). CONCLUSIONS: Radiographic analysis with use of the oblique posterior condylar view is technically easy and is accurate for the evaluation of radiolucencies of the posterior aspects of the femoral condyles after total knee arthroplasty.

Aged↗

PubMed2004

[Bone quantity and quality to its mechanical integrity].

Bone strength is made up of quantity (mass, mineralization), geometry (anatomy, micro architecture, collagen structure), and turnover/damage accumulation. While most of the mechanical behavior can be explained by measures of porosity, several additional descriptors of the geometry have been proposed for better predictions of fracture risk. This review introduces various aspects of these relationships between bone quantity and quality to its mechanical integrity.

Biomechanical Phenomena↗

PubMed2003

Mechanical effects of the intraarticular administration of high molecular weight hyaluronic acid plus phospholipid on synovial joint lubrication and prevention of articular cartilage degeneration in experimental osteoarthritis.

OBJECTIVE: To examine in vivo the effects of a mixture of high molecular weight hyaluronic acid (HA) plus phospholipids on joint lubrication and articular cartilage degeneration. METHODS: Experimental osteoarthritis (OA) of the right knee was induced by anterior cruciate and medial collateral ligament transection in 40 rabbits. The animals were subjected to 8 consecutive weekly intraarticular administrations of high molecular weight HA (the HA200 group), conventional molecular weight HA (the HA80 group), or high molecular weight HA plus L-delta dipalmitoyl phosphatidylcholine liposomes (the PHA group) and were killed 1 week after the final injection. The remaining transected right knees (the OA group) and randomly selected nontransected contralateral left knees (the control group) were collected simultaneously. Each group (n = 10) was divided into 2 equal subgroups, one of which was evaluated histologically while the other was subjected to a lubricating ability test using a pendulum friction tester. RESULTS: The injected knees had a tendency to demonstrate less damage to the articular cartilage compared with the OA group, and the histologic findings in all groups except for the PHA group differed significantly from the control group. There was a significant difference in the mean +/- SD friction coefficient between the control group (0.0100 +/- 0.00300) and the OA (0.0206 +/- 0.00649), HA200 (0.0190 +/- 0.00427), and HA80 (0.0177 +/- 0.00712) groups (P < 0.05 for each comparison), but not between the control group and the PHA group (0.0150 +/- 0.00330) (P = 0.15). CONCLUSION: To our knowledge, this is the first in vivo study to examine whether intraarticular injections of phospholipids influence joint lubrication by acting as a boundary lubricant, thus protecting articular cartilage from degenerative changes.

Animals↗

PubMed2003

Changes in anteroposterior stability following total knee arthroplasty.

This study evaluated the changes in anteroposterior stability at flexion and extension following posterior cruciate ligament (PCL)-retaining and PCL-substituting total knee arthroplasty (TKA), in comparison with normal knees. Altogether, 29 knees of 24 patients underwent either PCL-retaining ( n = 19) or PCL-substituting ( n = 10) TKA. Anteroposterior displacement was measured with a KT-2000 arthrometer preoperatively, 1 month after surgery, and again an average of 3 years after surgery. Anteroposterior stability at flexion and extension did not change following PCL-retaining TKA and was not significantly different from that of normal subjects, whereas anteroposterior stability increased following PCL-substituting TKA and was significantly greater than that of normal subjects an average of 3 years after surgery.

Adult↗

PubMed2003

Alignment in total knee arthroplasty following failed high tibial osteotomy.

In total knee arthroplasty (TKA) following failed high tibial osteotomy, the mechanical axis does not intersect the center of the tibial component if the tibia has been resected perpendicular to the anatomical axis. Therefore, tibial resection referencing the predicted postoperative mechanical axis instead of the tibial shaft axis is advocated. To obtain the optimal tibial resection, characteristics of the tibial proximal deformity were measured radiographically and predicted postoperative lower limb alignment was calculated using full-length, weight-bearing, lower limb anteroposterior radiographs. Two finite element analysis models also were examined. The proximal tibia was resected perpendicular to the tibial shaft axis in model 1, and perpendicular to the predicted postoperative tibial mechanical axis in model 2. When the proximal tibia was resected perpendicular to the tibial shaft axis, the predicted lower limb mechanical axis was significantly shifted medially to the center of the tibial joint surface. The results of the finite element analysis reflected the medial shift of the lower limb mechanical axis in model 1, where stresses were increased in the medial tibial compartment. Tibial resection referencing the predicted postoperative tibial mechanical axis, instead of the tibial shaft axis, should be performed, especially in cases with a deformed tibia.

Aged↗

PubMed2002

Factors affecting patellar tracking after total knee arthroplasty.

This study examined factors that influence patellar tracking after total knee arthroplasty. A total of 62 knees were evaluated radiographically for postoperative patellar tracking. Six factors were examined regarding their influence on postoperative patellar tracking. This study showed the effects of patellar component position, patellar resection angle, and lateral retinacular release on postoperative patellar tracking. There was no significant effect of the remaining 3 factors: the thickness of the patellar resection, preoperative patellar tilt, and rotational alignment of the femoral component. A medialized patellar component and obliquity of resection of the patella are effective for obtaining proper patellar tracking, whereas the evaluation of the influence of the external rotation of the femoral component requires more clinical studies.

Adult↗

PubMed2002

Patellar tracking and patellofemoral geometry in deep knee flexion.

Patellar tracking and femoral condylar geometry in deep knee flexion were evaluated using magnetic resonance imaging. The patellar tilting angle, patellar shift, and patellar anteroposterior translation from 0 degrees to 135 degrees flexion were measured. The depth of the femoral condylar articular surface and the curvature of the femoral condylar articular surface also were measured at 135 degrees flexion. The patella shifted laterally, tilted medially, and sank deeply into the intercondylar notch during deep knee flexion. The articular surface of the lateral condyle, existing deep within the intercondylar notch, began to curve steeply at a point farther from the center of the intercondylar notch than did the medial condyle. The geometry of the femoral condyle is adequate to fit the patellar geometry. Results of the current study suggest that the geometry of the lateral femoral condyle allows the patella to track smoothly with a larger patellofemoral contact area and less patellofemoral pressure during deep flexion.

Adult↗