Katsuro Iwasaki

Localisation of apoptosis and expression of apoptosis related proteins in the synovium of patients with rheumatoid arthritis.

OBJECTIVES: To investigate whether apoptosis occurs in the synovium of rheumatoid arthritis (RA), and the intermediate molecules operating in this process. METHODS: DNA fragmentation was detected by in situ nick end labelling (ISNEL) in the synovium of patients with RA (n = 11) and control patients with femoral neck fracture (n = 5). The expression of proteins p53, p21WAFI/CIPI, c-myc, proliferating cell nuclear antigen (PCNA), and Bcl-2 was also examined by immunohistochemistry. RESULTS: ISNEL positive synovial cells with apoptosis specific morphology were detected in extremely limited areas in only two RA synovial tissue specimens. Proteins p53, p21WAFI/CIPI, and c-myc, known inducers of apoptosis or cell cycle arrest or both, were expressed in the sublining cells independent of ISNEL positive cells. PCNA, a marker for cell proliferation, was observed in the synovial lining cells. Bcl-2, an inhibitor of apoptosis, was expressed mainly in infiltrated lymphocytes and in parts of the sublining layer cells of RA; it also did not correspond with ISNEL staining. CONCLUSIONS: Our findings indicate that RA synovial cells undergo apoptosis in addition to cell proliferation, but the frequency of apoptosis was very low. We suspect that the apoptotic process in the RA synovium may be suppressed by over-expression of Bcl-2. Although expressed proteins p53, p21WAFI/CIPI, and c-myc were present in the RA synovium, these protooncogenes are probably not implicated in the apoptotic process.

Effects of interleukin-1 beta on insulin-like growth factor-I autocrine/paracrine axis in cultured rat articular chondrocytes.

OBJECTIVE--To clarify the interaction of tissue destruction and repair of articular cartilage during inflammation, the effects of interleukin-1 beta (IL-1 beta) on the expression of insulin-like growth factor I (IGF-I), its receptor, and its binding proteins were examined. METHODS--Articular chondrocytes from five week rats were cultured in serum free medium treated with IL-1 beta (1-100 U/ml) for 24 hours. The concentration of IGF-1 in the conditioned medium was measured by RIA, and IGFBP were analysed by immunoligand blotting method. IGF-I receptors were also examined by [125I]IGF-I binding study. RESULTS--IL-1 beta induced the secretion of IGF-I and IGF-binding protein in chondrocytes; this was not inhibited by indomethacin (5 micrograms/ml). IL-1 beta also increased the number of IGF-I receptors but had no effect on receptor affinity. IL-1 beta inhibited chondrocyte proliferation, while exogenous IGF-I and growth hormone stimulated chondrocyte cell growth. IL-1 beta did not change IGF-I mRNA levels. CONCLUSION--IL-1 beta up-regulated the IGF-I autocrine/paracrine axis in cultured articular chondrocytes. These observations provide insight into the critical role played by IL-1 beta in tissue destruction and repair, and into the direct interaction between cytokines and growth factors associated with inflammatory arthropathy.

Degradation-resistant character of synthetic hydroxyapatite blocks filled in bone defects

The long-term changes of both the implanted hydroxyapatite (HA) blocks and the bone around them were observed radiologically to investigate the clinical usefulness of HA. HA blocks were used as a space filler in surgically created bone defects of seven cases due to curettage of bone tumours or removal for bone grafts, and they were followed up for 78 to 109 months. Bone formation around HA blocks peaked within 1 year after implantation, and then it faded gradually. However, shapes of HA blocks were rarely changed in all the cases. A clear zone around HA blocks was never observed . HA blocks were biocompatible and demonstrated a character resistant to degradation.

Ultrasonographic measurement of humeral torsion

This article presents a new method for the measurement of humeral torsion with the use of ultrasonography and discusses clinical applications of the method such as the evaluation of cubitus varus deformity after a supracondylar elbow fracture. Torsion angle increased 14 degrees from the time the patients were newborns to when they were adults. No significant difference was found between the right and left sides in healthy subjects. When humeral shaft or supracondylar fractures are treated, or when rotational deformities of the humerus are corrected, this method of measurement is very practical, because the humeral torsion of the unaffected side provides a standard for the individual. With this method of measuring humeral torsion, we also found that cubitus varus deformity after supracondylar fracture in children is caused not only by an increase in varus angulation but also by internal rotation of the distal fragment.

Idiopathic necrosis of the femoral epiphyseal nucleus in rats.

To study the cause of osteonecrosis of the femoral head in spontaneously hypertensive rats, the site and mechanism of the occlusion of the blood vessels feeding the femoral head were investigated histologically and microangiographically. Tracing the blood vessels using serial sections revealed that the lateral epiphyseal vessels disappeared immediately before entry into the ossific nucleus. As the reparative process advanced, the blood vessels from the lateral side of the head entered the ossific nucleus again. To investigate the relationship between osteonecrosis and mechanical stress on the femoral head, some treatments to reduce mechanical stress were applied, and the frequency of the femoral head lesions, such as osteonecrosis, disturbed ossification, and abnormality of the growth plate, was compared among the groups of treatments for stress relief. The incidence of femoral head lesions was found to be directly proportional to the mechanical stress working on the area, as was evident from a decrease in the incidence of osteonecrosis as a result of reduction of mechanical stress. Thus, the obstruction of the vessels in the lateral part of the femoral head might result from the breakdown of cartilage caused by the mechanical stress on the femoral head.

Necrosis of the femoral head in growing rats Occlusion of lateral epiphyseal vessels

The cause of the vascular occlusion in necrosis of the femoral head of growing, spontaneously hypertensive rats was investigated histologically using serial sections. The lateral epiphyseal vessels, which supply the proximal femoral epiphysis, disappeared immediately before entry into the femoral heads. In fresh osteonecrosis the pathway of the vessels between the margin of the articular cartilage and the growth plate was replaced with granulation or scar tissue. We conclude that the vascular occlusion occurs in the layer of the epiphyseal cartilage where the lateral epiphyseal vessels penetrate, and that the abnormalities of the epiphyseal cartilage might play a part in the occurrence of osteonecrosis.

Strength of the glenoid labrum and adjacent shoulder capsule

This study evaluates the role of the glenoid labrum and capsule in the prevention of shoulder dislocation. Fifteen shoulder joints from nine fresh cadavers were used. The labrum and capsule were cut into sections 5 mm wide, and the strength of each slice to rupture was measured. The rupture site was observed microscopically. The anterior-inferior portion was the weakest, with a mean force necessary to cause rupture of 3.84 +/- 1.00 kg/5 mm. The rupture site was the portion of the labrum close to the cartilage of the glenoid. Histologic structure and degenerative changes of the labrum did not differ in the anterior to posterior portions. These results show that the anterior-inferior portion of the labrum is relatively weak. This finding may explain the lesion commonly identified in anterior shoulder dislocation.

Growth hormone directly and indirectly stimulates articular chondrocyte cell growth

Although growth hormone (GH) is known to regulate cartilage growth and differentiation during development, it is still unclear whether the cell growth of articular chondrocytes is stimulated directly by GH or mediated by GH-induced insulin-like growth factor-I (IGF-I). In the present study, we focused on whether GH directly or indirectly stimulates articular chondrocyte proliferation. Monolayer articular chondrocytes from 5-week-old male Sprague-Dawley rats were cultured in Hams F-12/Dulbeccos modified essential medium supplemented with 10% fetal bovine serum. Stimulation of DNA synthesis by GH was dose-dependent between 0.1 and 1 microg/ml, and the maximum active concentration of GH was 500 ng/ml, which induced a 3.5-fold increase over control values. Anti-IGF-I antiserum neutralized about 80% of GH-induced DNA synthesis. GH stimulated the secretion of IGF-I into the conditioned medium in a dose-responsive manner. To determine whether GH stimulated DNA synthesis directly, we investigated the time-course changes in mRNA expression of IGF-I and the proto-oncogene c-myc. Induction of IGF-I mRNA occurred at 4 h, and reached a maximum level at 12 h, whereas the expression of c-myc mRNA was induced within 4 h, and continued to increase until 72 h after GH treatment. Furthermore, administration of cycloheximide, an inhibitor of protein synthesis, resulted in the superinduction of both IGF-I and c-myc mRNAs. These results suggest that early induction of c-myc is due to a direct stimulatory effect of GH, and that long-term induction of c-myc was attributable to an indirect effect of GH in which GH-induced secondary proliferative factors may act in an autocrine/paracrine manner. The superinduction of c-myc gene by cycloheximide also indicates that fresh protein synthesis of an intermediate protein was not required for GH-induced c-myc expression. Western ligand blot analysis of IGF-binding proteins revealed that cultured rat articular chondrocytes produced a predominant 41 kDa and a faint 32 kDa form, and that GH significantly stimulated the secretion of the 41 kDa form without affecting expression of the 32 kDa form. Furthermore, a specific IGF-I binding study suggested that the increase in DNA synthesis induced by GH was not associated with changes in affinity or in the number of IGF-I binding sites. These results support the conclusion that the stimulatory effect of GH was mainly mediated by GH-induced IGF-I production in monolayer rat articular chondrocytes. However, it is likely that GH may also have a direct stimulatory effect by inducing c-myc proto-oncogene expression.

Osteonecrosis of the femoral head in spontaneously hypertensive rats : relation to ossific nuclei during growth

We observed the distribution of the ossific nuclei and the occurrence of osteonecrosis in the femoral capital epiphysis of spontaneously hypertensive rats. In 270 femoral heads, the ossific nuclei were seen in the following sites of the epiphysis: Type 1, the lateral portion in 150 femoral heads; Type 2, the central portion in 5 heads; Type 3, both lateral and central portions in 12 heads; and Type 4, throughout the epiphysis in 62 heads. The number of femoral heads with osteonecrosis in Types 1-4 was 61, 0, 5, and 17, respectively.

Bone marrow plays a role in bone metabolism: Histomorphometry of iliac bone in postmenopausal women

SummaryWe conducted a histomorphometrical study on the role of the bone marrow in cancellous bone metabolism using iliac bone specimens from 79 postmenopausal women. A gradual decrease in hematopoietic tissue of the bone marrow was proportionate to the decrease in cancellous bone and the ratio of osteoid perimeter/bone perimeter regardless of age. On the other hand, the ratio of eroded perimeter/bone perimeter remained almost steady until hematopoietic tissue decreased significantly. These findings suggest that a change in the bone marrow, that is, a decrease in hematopoietic tissue, causes an imbalance in bone formation and resorption and leads to bone loss.