Moroe Beppu

Membrane-associated prostaglandin E synthase-1 is upregulated by proinflammatory cytokines in chondrocytes from patients with osteoarthritis

Prostaglandin E synthase (PGES) including isoenzymes of membrane-associated PGES (mPGES)-1, mPGES-2, and cytosolic PGES (cPGES) is the recently identified terminal enzyme of the arachidonic acid cascade. PGES converts prostaglandin (PG)H2 to PGE2 downstream of cyclooxygenase (COX). We investigated the expression of PGES isoenzyme in articular chondrocytes from patients with osteoarthritis (OA). Chondrocytes were treated with various cytokines and the expression of PGES isoenzyme mRNA was analyzed by the reverse transcription–polymerase chain reaction and Northern blotting, whereas Western blotting was performed for protein expression. The subcellular localization of mPGES-1 was determined by immunofluorescent microscopy. Conversion of arachidonic acid or PGH2 to PGE2 was measured by enzyme-linked immunosorbent assay. Finally, the expression of mPGES-1 protein in OA articular cartilage was assessed by immunohistochemistry. Expression of mPGES-1 mRNA in chondrocytes was significantly induced by interleukin (IL)-1β or tumor necrosis factor (TNF)-α, whereas other cytokines, such as IL-4, IL-6, IL-8, IL-10, and interferon-γ, had no effect. COX-2 was also induced under the same conditions, although its pattern of expression was different. Expression of cPGES, mPGES-2, and COX-1 mRNA was not affected by IL-1β or TNF-α. The subcellular localization of mPGES-1 and COX-2 almost overlapped in the perinuclear region. In comparison with 6-keto-PGF1α and thromboxane B2, the production of PGE2 was greater after chondrocytes were stimulated by IL-1β or TNF-α. Conversion of PGH2 to PGE2 (PGES activity) was significantly increased in the lysate from IL-1β-stimulated chondrocytes and it was inhibited by MK-886, which has an inhibitory effect on mPGES-1 activity. Chondrocytes in articular cartilage from patients with OA showed positive immunostaining for mPGES-1. These results suggest that mPGES-1 might be important in the pathogenesis of OA. It might also be a potential new target for therapeutic strategies that specifically modulate PGE2 synthesis in patients with OA.

Hypoxia upregulates the expression of angiopoietin-like-4 in human articular chondrocytes: role of angiopoietin-like-4 in the expression of matrix metalloproteinases and cartilage degradation.

The objective of this article was to investigate the role and expression of a novel adipocytokine, angiopoietin‐like‐4 (ANGPTL4), in arthropathy. Human chondrocytes were obtained from articular cartilage of patients with rheumatoid arthritis (RA) and osteoarthritis (OA), who underwent total knee or hip arthroplasty. Isolated chondrocytes were cultured under hypoxic (95% N2, 5% CO2) or normoxic conditions. The effects of hypoxia on ANGPTL4 expression were determined by real‐time reverse transcription polymerase chain reaction and Western blot analysis. We examined the role of ANGPTL4 using small interference RNA or by stimulating chondrocytes with recombinant ANGPTL4 protein. ANGPTL4 expression in the articular cartilage specimens was examined by immunohistochemistry. Hypoxia induced a significant increase in ANGPTL4 production (p < 0.05). Incubation of chondrocytes in vitro with recombinant ANGPTL4 enhanced the expression of matrix metalloproteinase (MMP)‐1 and MMP‐3. Downregulation of ANGPTL4 mRNA expression by siRNA diminished the expression of MMP‐1, but not that of MMP‐3, suggesting that each proteinase has a distinct response to ANGPTL4. Although the in vitro responses of chondrocytes to hypoxia were similar between RA and OA samples, the in vivo expression of ANGPTL4 had unique disease‐specific patterns, suggesting differences in oxygen tension in vivo. Human chondrocytes expressed ANGPTL4 and the expression was enhanced by hypoxia. ANGPTL4 might modulate cartilage metabolism by regulating MMPs.

Combination joint-preserving surgery for forefoot deformity in patients with rheumatoid arthritis

Proximal osteotomies for forefoot deformity in patients with rheumatoid arthritis have hitherto not been described. We evaluated combination joint-preserving surgery involving three different proximal osteotomies for such deformities. A total of 30 patients (39 feet) with a mean age of 55.6 years (45 to 67) underwent combined first tarsometatarsal fusion and distal realignment, shortening oblique osteotomies of the bases of the second to fourth metatarsals and a fifth-ray osteotomy. The mean follow-up was 36 months (24 to 68). The mean foot function index scores for pain, disability and activity subscales were 18, 23, and 16 respectively. The mean Japanese Society for Surgery of the Foot score improved significantly from 52.2 (41 to 68) to 89.6 (78 to 97). Post-operatively, 14 patients had forefoot stiffness, but had no disability. Most patients reported highly satisfactory walking ability. Residual deformity and callosities were absent. The mean hallux valgus and intermetatarsal angles decreased from 47.0 degrees (20 degrees to 67 degrees) to 9.0 degrees (2 degrees to 23 degrees) and from 14.1 degrees (9 degrees to 20 degrees) to 4.6 degrees (1 degree to 10 degrees), respectively. Four patients had further surgery including removal of hardware in three and a fifth-ray osteotomy in one. With good peri-operative medical management of rheumatoid arthritis, surgical repositioning of the metatarsophalangeal joint by metatarsal shortening and consequent relaxing of surrounding soft tissues can be successful. In early to intermediate stages of the disease, it can be performed in preference to joint-sacrificing procedures.

Absence of heat shock transcription factor 1 retards the regrowth of atrophied soleus muscle in mice

Effects of heat shock transcription factor 1 (HSF1) gene on the regrowth of atrophied mouse soleus muscles were studied. Both HSF1-null and wild-type mice were subjected to continuous hindlimb suspension for 2 wk followed by 4 wk of ambulation recovery. There was no difference in the magnitude of suspension-related decrease of muscle weight, protein content, and the cross-sectional area of muscle fibers between both types of mice. However, the regrowth of atrophied soleus muscle in HSF1-null mice was slower compared with that in wild-type mice. Lower baseline expression level of HSP25, HSC70, and HSP72 were noted in soleus muscle of HSF1-null mice. Unloading-associated downregulation and reloading-associated upregulation of HSP25 and HSP72 mRNA were observed not only in wild-type mice but also in HSF1-null mice. Reloading-associated upregulation of HSP72 and HSP25 during the regrowth of atrophied muscle was observed in wild-type mice. Minor and delayed upregulation of HSP72 at mRNA and protein levels was also seen in HSF1-null mice. Significant upregulations of HSF2 and HSF4 were observed immediately after the suspension in HSF1-null mice, but not in wild-type mice. Therefore, HSP72 expression in soleus muscle might be regulated by the posttranscriptional level, but not by the stress response. Evidence from this study suggested that the upregulation of HSPs induced by HSF1-associated stress response might play, in part, important roles in the mechanical loading (stress)-associated regrowth of skeletal muscle.

Outcome of medial displacement calcaneal osteotomy for correction of adult-acquired flatfoot.

Background: The results of medial displacement calcaneal osteotomy (MDCO) with flexor digitorum longus (FDL) tendon transfer were reviewed, as well as postoperative radiographic changes, to determine quantitative x-ray-based indications for MDCO with FDL tendon transfer in cases of adult-acquired flatfoot. Materials and Methods: Twenty-five patients, ages 42 to 71 years, underwent MDCO with FDL tendon transfer for stage II posterior tibial tendon dysfunction. Follow-up was 2.6 to 10.2 years. Preoperative and postoperative Japanese Society for Surgery of the Foot (JSSF), Foot Function Index, and SF-36 scores and physical and radiographic findings were compared. Eight measures of foot alignment were obtained from weight-bearing radiographs at 3, 6, 9, and 12 months after surgery and every 6 months thereafter. Differences in scores and values over time were analyzed statistically. Results: Average JSSF scores improved from 59 preoperatively to 91.3 postoperatively (p < .001). The only x-ray parameters that improved significantly and showed maintenance of the surgical correction were the lateral talometatarsal (LTMT) and tibiocalcaneal (TBC) angles. With preoperative LTMT and TBC angles of >25° and >15°, respectively, correction was inadequate. Conclusions: It was concluded that indications for MDCO with FDL tendon transfer in cases of adult-acquired flatfoot are a preoperative LTMT angle of <25° and hindfoot coronal alignment (TBC angle) of <15°. Level of Evidence: IV, Case Series

Gravitational unloading inhibits the regenerative potential of atrophied soleus muscle in mice

Aim:  The present study was performed to investigate the influence of unloading on the regeneration of atrophied and injured skeletal muscle.

Transplantation of myocyte precursors derived from embryonic stem cells transfected with IGFII gene in a mouse model of muscle injury.

Background. Reconstruction of skeletal muscle tissue is hampered by the lack of availability of functional substitution of the tissue. Methods. Embryonic stem (ES) cells were transfected with the insulin-like growth factor (IGF) II gene and were selected with G418. The resultant cell clones were analyzed regarding their myogenic differentiation in vitro and in vivo. Results. The cells expressed early and late myogenic differentiation markers, including myoD, myogenin, and dystrophin in vitro. They had phosphorylated Akt within the cells, suggesting their activation by the secreted IGFII. Transplantation of the cells to injured anterior tibial muscle of mice significantly improved their motor functions compared to injured mice transplanted with undifferentiated ES cells and injured mice given vehicle alone. The transfected cells adapted to the injured muscle, formed myofibers positive for dystrophin and negative for MyoD and myogenin. Trichrome staining and toluidine blue staining support myofiber formation in vivo. The enzymatic activity of acetylcholine esterase suggested the functional activity of the regenerated motor units. The evoked electromyogram of anterior tibial muscle transplanted with the transfected cells showed significantly higher potentials compared to that transplanted with undifferentiated ES cells and that injected with phosphate-buffered saline (control injury). Electron microscopic examination confirmed the myofiber formation in the cells in vivo. Conclusions. Transfection of IGFII gene into ES cells may be applicable for transplantation therapy of muscle damage due to injury and myopathies.

Biomechanical Analysis of the Stress Force on Midcarpal Joint in Kienböck's Disease

Two types of lunate were recognized in the midcarpal joint. Type I lunate has no facet articulation with the hamate, and Type II lunate has a facet articulation with the hamate. The purposes of this study are to estimate the biomechanical contribution of Type II lunate for Kienbocks disease, and to elucidate the change of the contact surface between the lunate and hamate during radial and ulnar deviation for both Type I and Type II. Twenty-four contralateral unaffected wrists with Kienbocks disease were used for the first purpose. The radiographic force analysis was performed with a modified two-dimensional rigid-body spring model computer-simulation technique. Six wrists of volunteers (3 of Type I and 3 of Type II lunates) were used for the second purpose. Dynamic examination on lunohamate joint was carried out using magnetic resonance imaging. The force distribution between the radius and Type II lunate was greater than that between the radius and Type I lunate statistically. Furthermore, the impingement of articular cartilages between Type II lunate and hamate was observed in ulnar deviation on dynamic study. These results suggest that Type II lunate was one of the anatomical risk factors for Kienbocks disease.

The carpal stretch test at the scapholunate joint

The purpose of this study was to evaluate the principle of the carpal stretch test. Eleven upper extremities from 6 fresh cadaver specimens and 40 normal wrists from 20 volunteers were used in this study. Changes in intercarpal distances (carpal interval ratio of the radioscaphoid, radiolunate, and lunocapitate joints) and step-off deformities at the scapholunate joint seen on the posteroanterior view of an x-ray film were analyzed with and without the carpal stretch test. In the cadaver wrists, the dorsal capsulotomy and radioscapholunate ligament (stage 1), the palmar half of the scapholunate interosseous ligament (stage 2), the dorsal half of the scapholunate interosseous ligament (stage 3), and the radioscaphocapitate ligament (stage 4) were sequentially sectioned. The carpal stretch test was completed in each stage. Each carpal interval ratio increased as each stage was added. Step-off deformities at the scapholunate joint were seen in 6 of 11 wrists in stage 2 and in 10 wrists in stages 3 and 4 with the carpal stretch test. In the normal wrists, neither gender nor wrist laxity (Garcias criteria) not influenced the results of the carpal stretch test. The carpal stretch test may be helpful in identifying occult and/or dynamic scapholunate dissociation.

An experimental study on initial fixation strength in transpedicular screwing augmented with calcium phosphate cement.

Study Design. An experimental study. Objective. To clarify the optimal insertion timing of transpedicular screws when the initial fixation strength reaches in maximum as calcium phosphate cement (CPC) hardens, in cases augmented by CPC to the vertebrae. Summary of Background Data. CPC goes easily into the bone trabeculae and excels in the bone compatibility. However, it is still unknown as for differences of fixation effects by CPC hardening time at actual insertion of the pedicle screw. Methods. Fifty-seven vertebrae obtained from 11 human cadavers. The CPC and titanium pedicle screws were used. Experimental groups were decided as follows. (1) Control group (without CPC). (2) CPC group (augmented with CPC); the mixed CPC infused into the screw hole, afterwards the pedicle screw inserted at a set time (passage time from the initiation of powder and liquid agent mixing). The CPC group was further divided into 3 subgroups, with respect to insertion time of the pedicle screws: 2, 5, and 10 minute subgroups. Maximum pull-out strength was compared, and cross sectioned specimens of the 5 and 10 minute groups were prepared and observed. Results. CPC group showed a pull-out strength of about 177% that of the control group. For inserting timing of the pedicle screw and pull-out strength, no apparent statistically significant difference was found between each subgroups, although the 10-minute group showed the lowest. Cross sectional observations revealed that the CPC diffused deeper into the bone trabeculae in the 5-minute group than in the 10 minutes. Conclusion. CPC augmentation enabled an average 77% increase of the maximum pull-out strength compared to the control group. The study of screw insertion timing augmented with CPC was indicative of the fact that an increase in the initial fixation of the pedicle screw can be achieved when the screw is inserted before initiation of CPC hardening.