Seisuke Tanaka

Cross-sectional Area of the Stenotic Lumbar Dural Tube Measured from the Transverse Views of Magnetic Resonance Imaging

The cross-sectional area of the lumbar dural tube was calculated from transverse-slice lumbosacral magnetic resonance images (MRI) using the simple geometric formulas and computerized digitizer in 51 patients with low-back pain only, 79 with mainly radicular symptoms, and 53 with intermittent claudication, and in 39 controls with confirmed symptomatic lesions at a nonlumbar level or of a nonspinal organ. Findings suggesting developmental narrowing of the spinal canal were found not only in the intermittent claudication group, but also in the radicular pain group. Cross-sectional area of < 100 mm2 at more than two of three (L2/3, L3/4, and L4/5) intervertebral levels was highly associated with the presence of intermittent claudication. The cross-sectional area value obtained with the simplified geometric formulas was highly correlated with that calculated with the digitizer, indicating that this simple method can be used with MRI in outpatient clinics for the rapid determination of the most stenotic portion of the dural tube.

Schmorl's nodes on magnetic resonance imaging : their incidence and clinical relevance

Schmorls nodes were observed in 76 (19%) of 400 patients with lumbar symptoms, and in 10 (9.4%) of 106 control patients. In the lumbar group, the highest incidence was 57%, in the second decade of life, and the lowest was 5%, in the sixth decade of life. Using MRI, among both groups, a total number of 218 Schmorls nodes were observed at 170 disc levels; however, plain x-ray revealed only 73 (33%) of them. There were associated posterior disc herniations at 39 disc levels in 30 cases (39%), most of which were at the L4/5 level. The ratio of the cases showing only Schmorls nodes to those with associated disc herniations at the same level increased markedly with age. Three of the four teenaged patients with multiple Schmorls nodes at four or more disc levels had a history of hard sports. Schmorls nodes, therefore, appear to be a type of vertical disc herniation, and to be an important pathognomonic condition, especially for young people.

Healing of segmental bone defects in rats induced by a β‐TCP‐MCPM cement combined with rhBMP‐2

A beta-tricalcium phosphate-monocalcium phosphate monohydrate (beta-TCP-MCPM) cement was evaluated as an effective carrier of recombinant human bone morphogenetic protein-2 (rhBMP-2) in rat femoral critical-size defects. Hard cement cylinders (4 x 5 mm) impregnated with two different doses of rhBMP-2 (1.26 or 6.28 microg) were implanted into each defect, and the results were compared with those in rats that had implantations of cylinders only. Implantation of the 6.28 microg dose of rhBMP-2 caused a large bone shell to form around the defect, resulting in osseous union in all cases within 3 weeks. Except for beta-TCP granules, the cement was resorbed and replaced by bone tissue at 6 weeks. A torsion test at 9 weeks showed that the failure torque and bone stiffness had recovered 99% and 141%, respectively, compared with the intact contralateral femur. The defects that received 1.26 microg of rhBMP-2 resulted in 40% union and 41% of the failure torque at 9 weeks. However, no instances of union were observed in the defects implanted with cylinders only. In conclusion, the beta-TCP-MCPM cement was shown to be effective as a rhBMP-2 carrier. Combined with rhBMP-2, this cement was rapidly resorbed and completely healed the defects.

Factors related to degradation of articular cartilage in osteoarthritis : A review

OBJECTIVES Osteoarthritis (OA) is a common joint deterioration initiated by multiple factors. To better understand related factors in the development of this disease, we focused on the mechanical stress loaded on articular cartilage. MATERIALS AND METHODS The anterior cruciate ligaments of rabbit knee joints were transected, and expression of protein kinase C (PKC) examined immunohistochemically. The PKC activator 12-o-tetradecanoyl-phorbol-13-acetate (TPA) was then administered intraarticularly. To determine the involvement of gas mediators, a cartilage defect was made on the medical femoral condyle of rabbit knee joints. Hydrostatic pressure was loaded on the cartilage taken from the surrounding defects, and levels of superoxide anion and nitric oxide (NO) were measured. Bovine chondrocytes were subjected to cyclic mechanical stretch using a Flexercell Strain Instrument. Proteoglycan synthesis and PKC activity were measured. Expression of matrix metalloproteinase (MMP)-3 and tissue inhibitor of metalloproteinase (TIMP)-1 in articular cartilages obtained from OA patients were examined using Northern blots. RESULTS Chondrocytes from experimentally induced OA were stained positively with anti-alpha-PKC antibody. Intraarticular administration of TPA prevented the development of OA changes. Cyclic tensile stretch loaded on chondrocytes decreased proteoglycan synthesis and PKC activity. Thus, PKC is involved in the stress-mediated degradation of articular cartilage. Cartilage defects led to degradation of surrounding cartilage and to enhanced superoxide anion and NO synthesis. We also noted increased and decreased expressions of MMP-3 and TIMP-1 mRNA in human OA cartilage, respectively. CONCLUSION PKC, gas mediators (superoxide anion, NO), and proteinases are all involved in OA.

A self-setting TTCP-DCPD apatite cement for release of vancomycin

Vancomycin (VCM), a methiciline-cefem resistant Staphylococcus aureus (MRSA)-specific antibiotic, was incorporated in a self-setting tetracalcium phosphate (TTCP)-dicalcium phosphate dihydrate (DCPD) apatite cement that hardened isothermally into a hydroxyapatite (HAP) phase with crystallinity similar to that of host bone. Effective release of VCM into PBS lasted for 2 weeks from cements containing 1% VCM and for longer than 9 weeks from cements containing 5% VCM. The rate of release of VCM differed between cements with different crystallinities as well as between the two dissolution media, PBS and simulated body fluid. Mean concentration of VCM in the bone marrow tissue released from cements containing 5% VCM was 20 times the minimum inhibitory concentration 3 weeks after implantation in bone. Direct contact with new bone was observed with the cements containing 1% VCM. Slow delivery of VCM from a self-setting TTCP-DCPD apatite cement with low crystallinity could be used to treat MRSA osteomyelitis.

Hyaluronic acid inhibits interleukin-1-induced superoxide anion in bovine chondrocytes

Abstract.Objective: To examine the effect of hyaluronic acid (HA) on the induction of superoxide anion by IL-1 in chondrocytes. ¶Materials and Methods: Bovine articular chondrocytes were treated with different concentrations of IL-1. A chemiluminescent probe (L-012) was added to the medium and chemiluminescence detection was used to measure superoxide anion. ¶Results: IL-1 caused induction of superoxide anions in a dose-dependent manner. HA (10–100 g/ml) countered superoxide induction caused by 20 ng/ml of IL-1. ¶Conclusion: HA can afford protection against cartilage degradation, probably acting as a free-radical scavenger.

Concurrent generation of nitric oxide and superoxide inhibits proteoglycan synthesis in bovine articular chondrocytes : involvement of peroxynitrite

OBJECTIVE Nitric oxide (NO), widely assumed to be a mediator of interleukin 1 (IL-1), inhibits proteoglycan synthesis in articular chondrocytes. IL-1 also produces superoxide anion. We hypothesized that the IL-1 inhibited proteoglycan synthesis is the result of peroxynitrite formed by the reaction of NO with superoxide. METHODS Bovine articular chondrocytes were cultured in the presence of SIN-1, which leads to simultaneous generation of both NO and superoxide. Proteoglycan synthesis was measured based on the incorporation of [35S] sulfate, and the presence of peroxynitrite was confirmed using immunohistochemistry. RESULTS SIN-1 inhibited proteoglycan synthesis and superoxide dismutase reversed SIN-1 inhibited proteoglycan synthesis, indicating the simultaneous generation of superoxide is essential to inhibit proteoglycan synthesis. IL-1 induced peroxynitrite in articular chondrocytes and addition of peroxynitrite inhibited proteoglycan synthesis. CONCLUSION The concurrent generation of superoxide anion and NO is required for the action of IL-1 to inhibit proteoglycan synthesis. Peroxynitrite is a candidate for this underlying mechanism.

Cyclic tensile stretch on bovine articular chondrocytes inhibits protein kinase C activity

Osteoarthrosis, a common pathway of joint deterioration, is caused by mechanical stress loaded on articular cartilage. We previously demonstrated the involvement of protein kinase C (PKC) in the development of osteoarthritis in vitro. In this study, we examined the effect of mechanical stress on chondrocyte metabolism and the activity of PKC in vitro. Low frequency and magnitude of cyclic tensile stretch loaded on chondrocytes increased proteoglycan synthesis. However, high frequency and magnitude of stress decreased its synthesis. In this condition, activity of PKC was reduced. These results suggest an involvement of PKC in the stress-mediated inhibition of proteoglycan synthesis.

ZONAL DIFFERENCES IN NITRIC OXIDE SYNTHESIS BY BOVINE CHRONDROCYTES EXPOSED TO INTERLEUKIN-1

To determine the role of nitric oxide (NO) in the inhibition of aggrecan synthesis, we measured levels of NO produced by bovine chondrocytes from different layers of articular cartilage in the presence of interleukin-1 (IL-1). Chondrocytes from the superficial layer showed a large increase in NO synthesis in response to IL-1. Although chondrocytes from the deep layer also produced NO in response to IL-1, the amount was less than that from the superficial layer. Enhanced NO production evoked by IL-1 was accompanied by a significant inhibition of aggrecan synthesis. These data suggest that chondrocytes in both superficial and deep layer of articular cartilage inhibit aggrecan synthesis with IL-1 via NO production. In addition, superficial layer cells respond to lower amounts of IL-1 with respect to NO-production and inhibition of proteoglycan synthesis.

Classification of the callus in limb lengthening Radiographic study of 35 limbs

35 calluses formed during limb lengthening were classified radiographically into 6 types: external, straight, attenuated, opposite, pillar, and agenetic. The healing indexes correlated well to the intrinsic periosteal and endosteal conditions of each type. This classification enabled us to estimate the intrinsic conditions, predict the healing index, control the daily lengthening speed, and decide to apply early augmentation of the callus.