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Biomedical subjects

K Hirohata

Publications and source records attributed to K Hirohata.

At least 37 records · Page 2Linked to original sources
PubMed1991

The response of osteocytes to a lipid clearing agent in steroid-treated rabbits.

We studied the effect of a lipid clearing agent (clinofibrate) on the osteocytes of rabbits treated with corticosteroids. Thirty-one rabbits were divided into four groups: (A) steroid-treated with a normal diet, (B) steroid-treated and one a diet with added clinofibrate, (C) non-steroid-treated, on a diet with clinofibrate; and (D) non-steroid-treated on a normal diet. All the steroid-treated animals demonstrated hyperlipidaemia and fatty degeneration of the liver. Lipid-containing osteocytes were seen in the femoral heads of these animals. However, those which received clinofibrate (group B) had less severe lipidaemia, and less severe degeneration of the liver. In them, only the osteocytes around the haversian canals exhibited lipid inclusions. Clinofibrate appears to modify lipid metabolism, diminishing the steroid induced accumulation of lipids within osteocytes. This effect may protect against steroid-mediated osteonecrosis.

Adrenal Cortex Hormones↗
PubMed1991

Anatomical study on the menisco-femoral ligaments of the knee.

The menisco-femoral ligaments are important accessory ligaments of the knee. They extend from the posterior horn of the lateral meniscus to the lateral aspect of the medial femoral condyle close to the femoral attachment of the posterior cruciate ligament. Most of the authors reported that in some cases these ligaments are absent. But in the 100 knees that we carefully examined, obvious menisco-femoral ligaments were identified in all of the specimens. When the anatomical relationship between the menisco-femoral ligaments and the lateral meniscus is considered, it can be easily speculated that the menisco-femoral ligaments draw the posterior horn of the lateral meniscus in anterior, medial and superior direction during flexion of the knee joint. Thus, the congruency between the lateral meniscus and femoral condyle and the stability of the knee joint increase.

Adult↗
PubMed1991

Enhancement of new bone formation by hematoma at fracture site.

In order to study the osteogenetic potential of fracture hematoma, pellets which contain fluid components extracted from human fracture hematoma were transplanted to the subperiosteum of the rat parietal bone. Furthermore we have examined the effect of the fluid extract of the fracture hematoma and factors partially purified from this extract on DNA synthesis of cultured osteoblast-like cell line MC3T3E1. Implantation of the pellets containing the fluid extract did not promote new bone formation regardless of the presence of periosteum. This extract, in contrast, enhanced DNA synthesis of osteoblast-like cell line MC3T3E1 in a concentration dependent fashion. When this fluid extract was partially purified by ion exchange chromatography, the highest peak in DNA synthesis of MC3T3E1 was attained at 38mM NaCl, and the second highest peak at 290mM. These results suggest that the soluble extract from fracture hematoma contains growth factors which promote osteoblast proliferation, but does not possess osteogenetic potential.

Animals↗
PubMed1991

[Steroid induced early changes of the femoral head in man--histological study of autopsied cases].

High dose corticosteroid therapy constitutes one of major causes of osteonecrosis of the femoral head. To examine the early changes of the femoral head induced by corticosteroid therapy, 20 femoral heads were obtained at autopsy and the other 19 femoral heads without having been on steroid were served as controls. Histological examination from steroid treated group revealed that in areas of subchondral bone there were observed necrotic changes of osteocytes. The nucleus was so pressed to one side of the cell as to assume crescent like aspect. When stained with Sudan IV, fat positive materials were found in the osteocyte lacunae. Electron micrographic examination revealed intracellular fat as low electron dense droplets in these degenerative osteocytes. Examination of bone marrow showed an increase of the number of fat cells in steroid treated group. These changes in man may represent some failure in lipid metabolism, although it is unknown whether these events may produce osteonecrosis of the femoral heads.

Adrenal Cortex Hormones↗
PubMed1991

Long-term results of posterior release surgery for severe flexion contracture of the knee in patients with rheumatoid arthritis.

Twelve knees in nine rheumatoid patients with severe flexion contractures were evaluated clinically and roentgenographically for an average of 17.2 years (range, six to 25 years) after posterior release surgery. Preoperatively, the average extension in the 12 knees was 42.5 degrees, and postoperatively it was 10.8 degrees. Even though patients were able to walk postoperatively, the majority had knee pain when they extended their knees soon after surgery. Seven knees required further surgery after correction of the flexion deformity. The average time before reconstructive surgery after posterior release was 11.1 months. In the treatment of severe flexion deformities of the knee in patients with rheumatoid arthritis, posterior release surgery was effective only in correcting the deformity. Posterior subluxation of the tibia, knee pain, and instability occurred soon after surgery. Therefore, patients may require additional reconstructive surgery soon after the posterior release.

Adolescent↗
PubMed1990

Localization and identification of root canal bacteria in clinically asymptomatic periapical pathosis.

Twenty-one teeth with clinically asymptomatic periapical pathosis (class 3) were extracted and the isolation, identification, and localization of bacteria in the root apex were examined. Mixtures involving several bacteria were isolated from more than 60% of the cases. Scanning electron microscopy revealed bacterial masses to be associated with the apical part of the root canal, but not with the area of apical foramen or on the surface of root apex. Our results indicate that the bacteria in class 3 cases may be derived from organisms which colonized before or during endodontic treatment, but not from anachoresis. The bacteria-positive cases of asymptomatic periapical pathosis have the potential to progress to symptomatic periapical pathosis.

Actinomyces↗
PubMed1990

Analysis of lymphocyte subsets of bone marrow in patients with rheumatoid arthritis by two colour immunofluorescence and flow cytometry.

Lymphocyte subsets defined by monoclonal antibodies were investigated in bone marrow and peripheral blood of 17 patients with rheumatoid arthritis (RA); 13 patients with osteoarthritis or aseptic necrosis served as controls. Patients with RA were found to have a raised OKT 4/8 ratio both in bone marrow and peripheral blood in comparison with the controls. Furthermore, bone marrow of RA showed a lower percentage of OKT 8+ T cells than that of controls. The percentage of HLA-DR+ T cells was higher in bone marrow than in peripheral blood of RA, though a slightly lower percentage was detected in bone marrow than in peripheral blood of controls. Thus T cell subsets in bone marrow of RA differ significantly from those of controls. Patients with RA had a higher OKT 4/8 ratio and a higher percentage of HLA-DR+ T cells in bone marrow than controls, suggesting that T cell subsets in bone marrow of RA are in an immunologically activated state and that T cell subsets are affected by rheumatoid inflammation in bone marrow of RA.

Adult↗
PubMed1990

The osteogenetic potential of fracture haematoma. Subperiosteal and intramuscular transplantation of the haematoma.

We studied the precise role of the fracture haematoma in healing by the experimental transplantation of the haematoma at two days and four days after fracture of the rat femur to subperiosteal and intramuscular sites. We used bone marrow and peripheral blood haematomas for control experiments. The transplanted two-day fracture haematoma produced new bone by endochondral ossification at the subperiosteal site, but not at the intramuscular site. Four-day fracture haematoma produced new bone formation at both subperiosteal and intramuscular sites. These results suggest that fracture haematoma has an inherent osteogenetic potential.

Animals↗
PubMed1990

Increased superoxide anion release from chondrocytes in response to interleukin 1 and interferons.

In order to investigate a possible mechanism of degradation of cartilage matrix in chronic inflammation, superoxide anion (O2-) release from chondrocytes after stimulation with interleukin 1 (IL 1) and interferons (IFNs) has been studied. Both of these cytokines enhanced O2- release in a dose- and time-dependent fashion. Increased of the O2- release by these cytokines inactivated by heat or acid pretreatment was not observed. These results suggest that the cytokines released in the process of local immune reactions can stimulate the chondrocytes to promote generation and release of O2-. Released O2- may be associated with degradation of cartilage matrix by chondrocytes themselves activated in the process of chronic arthritis.

Animals↗
PubMed1990

Association of HLA-DR antigens with disease severity in Japanese patients with rheumatoid arthritis.

Twenty eight Japanese patients with rheumatoid arthritis (RA) were tested for HLA-DR antigens to investigate genetic influence on disease severity and prognosis. The severity of RA was assessed by clinical, laboratory and radiological indexes. HLA-A, B, C and DR typing was performed using sera described at the 3rd Asia and Oceania Histocompatibility Workshop. HLA-DR4.1 was significantly higher in RA patients (50%) compared with controls (27.6%). HLA-DRw53 was also higher in RA patients, although DRw52 was lower in those than controls. When the relationship between HLA-DR antigens and the clinical severity of RA was investigated, the patients with HLA-DR4 had a severer disease than DR4 negative patients. In contrast, HLA-DR2 positive patients had significantly better functional scores than DR 2 negative patients. We next investigated specific genes likely to be directly involved in the pathogenesis of RA. Although the new restriction fragment length polymorphisms (RFLPs) were found in DR2 positive patients, no association was found between the RFLPs and the clinical severity of RA. Furthermore there were no differences in the frequencies of the RFLPs in HLA-DR4 positive patients compared with DR4 negative patients. It may be concluded that the severity of RA appears to be influenced by several different genes or molecules rather than by a single gene or gene product linked to HLA-DR2 or DR4.

Adult↗
PubMed1990

[Knee synovitis in a rheumatoid patient with separated joint cavity].

A 40-year-old female patient with seropositive rheumatoid arthritis of 10 years duration. She had performed a total knee replacement of her left knee. At surgery the suprapatellar pouch was found to be separate from the rest of the knee joint, where direct access to the articular collagenous tissue remained. The suprapatellar pouch, presumable separate from the knee cavity since birth, was free of disease. The rest of the knee joint had gross and histopathological evidence of severe rheumatoid synovitis. The sparing of this suprapatellar pouch by rheumatoid disease is not easily explained, but the finding of this case suggests that synovium and articular collagenous tissues are requisites of chronic rheumatoid arthritis.

Adult↗
PubMed1990

Fatty degeneration of osteocytes of the fourth metatarsus in patients with idiopathic necrosis of the femoral head.

(1) Bone biopsies from the femoral heads and the fourth metatarsal head were obtained in the patients with idiopathic necrosis of the femoral head and with rheumatoid arthritis. (2) 71.4% of the patient with idiopathic necrosis of the femoral head revealed fatty degeneration of osteocytes in either the femur and/or metatarsus. (3) 57% of those patients demonstrated hyperlipidemia. (4) Metatarsal biopsies obtained from the patients with rheumatoid arthritis disclosed no fatty degeneration of osteocytes except in one patient treated with steroids.

Adult↗
PubMed1990

Clinical and histologic observations of monoarthritis. Anticipation of its progression to rheumatoid arthritis.

Synovial biopsies were performed on 84 patients with monoarticular synovitis from 1960 to 1984. Twenty-seven (32%) of 84 patients were pathologically differentiated; however, the other patients remained classified as nonspecific monoarthritic. Follow-up studies of nonspecific monoarthritis ranging from five to 25 years (average, 15 years) were carried out in 34 patients. Five patients (15%) disclosed polyarticular involvement and were diagnosed as having classic rheumatoid arthritis (RA) within five years after initial biopsy (RA group). In the remainder (non-RA group), 19 patients recovered completely and nine of ten patients complained of a slight degree of joint involvement. A good prognosis was observed in younger patients and in those who showed minimal histologic changes in the synovium. Initial laboratory examinations, including a white cell count, erythrocyte sedimentation rate, C-reactive protein, and agglutination test, did not show any differences between the RA and the non-RA groups. To determine predicting factors for RA, a comparative histologic study of the initial specimens was performed. Specimens from the RA group showed a predominant appearance of lymphoid aggregates, high endothelial postcapillary venules, and proliferative plasma cell infiltration. These histologic features suggest the future appearance of RA; therefore, careful observation and early treatment should be considered for these patients.

Activities of Daily Living↗
PubMed1990

Posterior interosseous nerve syndrome associated with rheumatoid synovial cysts of the elbow joint.

Three rheumatoid arthritis patients developed synovial cysts of the elbow joint and an acute compression neuropathy of the posterior interosseous nerve. All patients had weakness of the finger extensors; in one the extensor tendons were explored before the exact diagnosis was made. Intraarticular steroid injections were effective in one patient. In the other two patients surgical decompression of the radial nerve and elbow synovectomy with radial head resection were curative. Although relatively rare, the diagnosis of an antecubital cyst must be considered when complications such as a nerve compression syndrome are present.

Adult↗