Biomedical subjects

H Iwata

Publications and source records attributed to H Iwata.

At least 307 records · Page 17Linked to original sources

PubMed1997

Prostaglandin levels of primary bone tumor tissues correlate with peritumoral edema demonstrated by magnetic resonance imaging.

BACKGROUND: Several reports have shown peritumoral edema accompanying primary bone tumors demonstrated by magnetic resonance imaging (MRI). However, the mechanism of this inflammatory reaction is still unclear. The authors postulated that the reaction was caused by some chemical mediators including prostanoids, because several investigators have observed that some types of bone tumors synthesize prostanoids. Therefore, the authors compared MRI findings and tumor prostaglandin (PG) levels. METHODS: The subjects were 29 patients with primary bone tumor or tumor-like conditions: chondroblastoma (n = 5); chondrosarcoma, including rare variants (n = 8); giant cell tumor (n = 6); osteochondroma (n = 5); osteoblastoma (n = 2); Ewing's sarcoma (n = 2); and eosinophilic granuloma (n = 1). T1- and T2-weighted spin echo images were obtained in all but one patient before surgery. The tumor concentration of prostaglandin E2, 6-keto-PGF1 alpha, and thromboxane B2 were measured by radioimmunoassay. RESULTS: MRI distinctly showed bone marrow edema in 9 and soft tissue edema in 12 of the 28 patients examined. These findings were significantly correlated with the PG levels. Moreover, the PG levels were correlated with the histologic classifications (P < 0.001). In particular, the chondroblastomas showed prominent concentrations of PGs compared with other cartilaginous tumors or giant cell tumors. CONCLUSIONS: Although peritumoral edema accompanying benign and malignant bone tumors is not necessarily related to one single pathophysiologic mechanism, these results suggest that PG production was an important cause of the inflammatory reaction that was revealed by MRI. Recognition of this phenomenon is advantageous not only for strict diagnostic purposes but also for understanding the characteristic features of individual primary bone tumors.

6-Ketoprostaglandin F1 alpha↗

PubMed1997

Chemotherapy-induced expression of alpha B-crystallin in neuroblastoma.

Since alpha B-crystallin is known to be expressed in glial tissues of human brain and neuroectodermal tumors, the alpha B-crystallin content of neuroblastomas, may be related to the degree of glial or neuronal differentiation. The alpha B-crystallin content of 73 neuroblastomas, was determined by enzyme immunoassay. The concentration of alpha B-crystallin was examined in light of neuroblastoma prognostic factors. Neuroblastomas from patients who received chemotherapy (n = 23) contained higher concentrations of alpha B-crystallin than those from patients who did not receive chemotherapy (n = 50) (P > 0.05). There was a statistically significant difference in alpha B-crystallin concentrations in advanced stage patients who received preoperative chemotherapy (P < 0.01). Immunohistochemistry demonstrated alpha B-crystallin expression in the nerve-like fibers and a few ganglion-like cells. Staining was not apparent in the less differentiated cells in the tumor cell nest. alpha B-crystallin may play a role in the response to cellular stress in neuroblastoma.

Adolescent↗

PubMed1997

Nontoxic embolic liquids for treatment of arteriovenous malformations.

Interventional radiology is becoming one of the standard treatments of arteriovenous malformation (AVM). Cyanoacrylate derivatives and polymer solutions are widely used to occlude the AVM nidus by their injection through a catheter, but they are far from satisfactory embolic liquids. For instance, cyanoacrylate derivatives sometimes glue the catheter to the artery, resulting in serious complications; in addition, the organic solvents used to dissolve polymers cause damage to the surrounding brain tissue of the AVM. Therefore, we attempted to develop embolic liquids by dissolving poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) in Iopamiron with an addition of a small amount of ethyl alcohol. This new embolic liquid is not cytotoxic and is easily injected into the AVM through a thin, long catheter to effectively occlude the AVM.

Animals↗

PubMed1997

Carcinogenicity test of 50 Hz sinusoidal magnetic fields in rats.

Male and female F344 rats, 48 per exposure group, were sham exposed (Group A) or exposed to 0.5 (Group B) and 5 mT (Group C) magnetic fields for two years. Animals were exposed from 5-109 weeks of age in SPF conditions according to the OECD test guideline No. 451. Average exposure was 22.6 hr/day. No significant differences in body weight and food consumption were observed between the sham and exposed groups. At the end of the exposure period, survival rates of the male rats were 73, 83, and 79%, and those of the females, 77, 79, and 75% for Groups A, B, and C, respectively, with no significant differences between groups. Differential counts of leukocytes were measured at the 52nd, 78th, and 104th weeks of exposure and no significant differences were observed between the exposure groups. All survivors were euthanized on schedule, and all the organs and tissues suspected of tumoral lesions were examined histopathologically. Incidences of mononuclear cell leukemia in the male and the female rats were 5, 4, 4 and 8, 6, 7 for Groups A, B and C, respectively; incidences of malignant lymphoma in the female rats were 0, 1 and 1. Neither significant increases nor acceleration of incidence of leukemia were observed. Incidences of brain and intracranial tumors did not increase in the exposed groups. Incidences of both benign and malignant neoplasms showed no significant difference between the exposed and sham exposed groups with one exception: fibroma of the subcutis in the male rats, which was considered not to be a statistically significant when evaluated with respect to the historical control data in our laboratory.

Animals↗

PubMed1997

Transtrochanteric rotational osteotomy for osteonecrosis of the femoral head. 43 patients followed for at least 3 years.

We reviewed 48 hips in 43 patients 3-7.1 years (average 4.6 years) after Sugioka transtrochanteric rotational osteotomy for osteonecrosis of the femoral head. The average age at operation was 41 years. Thirty-four patients were men and 9 women. Overall results at the final follow-up were satisfactory in 30 hips (62%). Kaplan-Meier's survivorship was 62% at 3 years and 60% at 5 years postoperatively. Six hips for which the ratio of the intact area of the articular surface on the preoperative lateral radiograph was less than 30% showed further collapse. Five hips were converted to bipolar hemiarthroplasties or total hip arthroplasties. Complications, such as varus deformity, subtrochanteric fracture, and ectopic bone formation, occurred in eight hips. Five of them were operated on in the first 2 years of this series. Three of these five operations had unsatisfactory results. We conclude that satisfactory results can be achieved using this osteotomy by maintaining exact surgical technique and by limiting the surgical indications to hips with an intact area of more than one-third of the entire articular surface on the lateral radiograph of the femoral head.

Adolescent↗

PubMed1997

Vascularized pedicle bone-grafting for nontraumatic avascular necrosis of the femoral head. A 5- to 11-year follow-up.

We investigated the results of 31 hips in 26 patients with nontraumatic (n = 20) and steroid-induced (n = 6) avascular necrosis of the femoral head (ANFH) treated with vascularized iliac pedicle bone graft (PBG). The average age at operation was 38.3 years. Three were women and 23 men. The average follow-up was 8.0 years. The Harris hip score prior to operation and at latest follow-up improved from 62 to 83; one hip collapsed and was revised with a bipolar endoprosthesis. At the final follow-up, 19 hips (63%) were clinically rated as good to excellent, 4 fair, and 7 poor. At the final follow-up, 15 of 27 hips (56%) of stage II before operation showed progressive collapse after bone grafting. In steroid-induced ANFH, in three women, 2 of 4 hips showed poor results. These results are only slightly better than those of core decompression and no better than those obtained after decompression and simple nonvascularized grafts to provide support for the subchondral bone. We concluded that vascularized PBG is sometimes indicated for ANFH in an early stage before collapse of the femoral head.

Adult↗

PubMed1997

Use of adriamycin-impregnated methylmethacrylate in the treatment of tumor metastases in the long bones.

Internal fixation or endoprosthetic replacement of a long bone metastatic lesion was performed using adriamycin-containing bone cement (methylmethacrylate) after resection or curettage of the lesion in 25 patients (27 limbs). Survival rate, limb function, and local recurrence rate were retrospectively evaluated in this patient cohort. Survival rate was 53% at 12 months and 30% at 24 months, which was better than in previous reports. One patient showed local recurrence radiographically. Postoperatively, none of the patients developed infection, delayed wound healing, myelo-suppression attributed to adriamycin, and 74% of the patients were able to walk outdoors.

Adolescent↗

PubMed1997

Malignant hemangioendothelioma of the left calcaneus associated with fever and hematological abnormalities.

A case of malignant hemangioendothelioma of the left calcaneus associated with unique system manifestations is reported here. The severe toxic manifestations included: high fever, anemia, leukocytosis, coagulation abnormalities, and other signs. Because of poor response to many antibiotic regimens, the confusion of diagnosis, and severe coagulation abnormalities with clinical signs that the life of the patient was endangered, below the knee amputation was performed. Pathological studies revealed a malignant hemangioendothelioma. A review of the case suggests that the signs and symptoms were possibly due to an immune response to the tumor rather than to secondary infection, although the latter possibility cannot be completely excluded.

Adult↗

PubMed1997

Magnetic resonance imaging of osteonecrosis in divers: comparison with plain radiographs.

OBJECTIVE: To assess the diagnostic value of magnetic resonance imaging (MRI) as compared with radiographic findings in osteonecrosis in divers. DESIGN AND PATIENTS: MRI scans and conventional radiographs of the shoulder, hip and knee joints of 23 professional male scuba divers were reviewed together with their clinical findings and personal histories. Correlations between the MRI findings and the radiographic evaluation, clinical symptoms, and personal history were then investigated. RESULTS AND CONCLUSIONS: Lesions found on MRI in 23 divers included 27 in 39 proximal humeri, 17 in 36 proximal femora, 13 in 32 distal femora, and 12 in 32 proximal tibiae. Diffuse, marginated, or irregular patterns were observed. No lesions were seen in epiphyses of the distal femur or proximal tibia. We tried to classify these MRI findings by location and appearance. MRI showed no patients with only one affected bone. A close correlation between the MRI findings and maximum diving depth was observed in the proximal humerus. MRI depicted bone lesions that could not be detected on the radiographs. A routine MRI investigation of the hip joints should be performed in every diver in whom osteonecrosis is diagnosed at another site, for early detection of femoral head osteonecrosis. MRI of the shoulder joint is also the best surveillance in divers who dive deeper than 15 m.

Adult↗

PubMed1997

The immunosuppressive effect of fresh allogeneic bone graft in mice.

We investigated the immunosuppressive effect of fresh bone allografts after donor specific spleen cell transfusion in mice. Allografts from major histocompatibility complex incompatible mice were performed one week after the transfusion. Cellular and humoral immune responses were recorded by measuring alloreactive cytotoxic T-lymphocyte activity and antibody activity. Survival in days of a second set skin graft was measured for determining clinical immunity. Alloreactive cytotoxic T-lymphocyte activity was stimulated at 17 days (10 days after bone grafting) and then suppressed at 31 days (24 days after bone grafting). The survival of the second set skin graft was not diminished at this time. This outcome indicates that the spleen cell stimulated cellular immune response was suppressed after fresh bone allografts, suggesting that these allografts have an immunosuppressive effect and induce immunosuppressive actions.

Animals↗

PubMed1997

Proposal for hand-arm vibration exposure limits adopted for Japanese workers operating hand-held vibration tools.

On the basis of data presented in our previous, reports, the current study was undertaken to estimate frequency-weighted hand-arm vibration exposure limits for various daily exposure times. The procedures for the present study were as follows. (1) The prevalence of vibration-induced white finger (VWF) as well as the vibration exposure were investigated in various groups of workers operating hand-held vibrating tools. The vibration magnitude of various tools was measured and the results were presented as the energy-equivalent frequency-weighted root-mean-square (m/s2 rms) acceleration. There was a statistically significant positive correlation between the prevalence of VWF and the measured vibration magnitude (R2 = 0.5, P < 0.05). Hence, it was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be considered. (2) By a careful selection of available publications which contain useful information on duration of vibration exposure of < or = 2 h/day and the occurrence of VWF, a significant correlation between the prevalence of VWF and the vibration magnitude could be observed. The regression equation was estimated as: y = -18.5 + 4.6 (x), R2 = 0.8. On the basis of this equation, it was speculated that the prevalence of VWF in workers using vibrating tools might be restricted to the prevalence of Raynaud's phenomenon in the Japanese general population if the 2-h daily vibration exposure is about 4.5 m/s2 rms. (3) Regarding this speculation, the equation provided in the documentation of ISO 5349 was used and modified as: [alpha h,w)eq,t = (alpha h,w)eq,2(2/t)1/2 (m/s2 rms)] and then the vibration limit values for daily exposure of 1 min to 8 h were calculated. (4) In order to achieve compatibility with standards of other countries, and to formulate an easy method for using the recommended values presented here, the daily exposure time of 8, 4, 2, 1 and 0.5 h were selected. The correspondence vibration magnitudes were in the range 22-9.0 m/s2 rms, and the lower limit (2.2 m/s2 rms) was assumed as the permissible vibration exposure limit for an 8-h working period. The proposed daily vibration limits were then compared with those recommended by other institutions.

Adult↗

PubMed1997

Assessment of hand-arm vibration exposure among traffic police motorcyclists.

The aims of this study were (1) to evaluate subjective symptoms in the hand-arm system of all traffic police motorcyclists of a city located in the central part of Japan and (2) to assess their hand-arm vibration exposure associated with traffic police motorcycle riding. The study population consisted of 119 motorcycling traffic policemen and 49 male controls. By means of a questionnaire, information on the occupational history and the presence of subjective symptoms in the hand-arm system of all subjects was obtained. Vibration was measured on the handlebars of the representative motorcycles and on the hands of the riders. The 4- and 8-h energy-equivalent frequency-weighted acceleration as well as the lifetime vibration dose were calculated for all police motorcyclists. The prevalence of finger blanching in the traffic police motorcyclists was 4.2%, but none of the controls had this symptom. The rates of finger numbness (19.3%), finger stiffness (16.0%), shoulder pain (13.4%), and shoulder stiffness (45.4%) were significantly higher among police motorcyclists as compared with controls. The root-mean-square (rms) frequency-weighted acceleration on the handlebars of police motorcycles was in the range of 2.2-4.9 m/s2 rms. The computed 4- and 8-h energy-equivalent frequency-weighted acceleration values were 2.8-4.5 and 2.0-3.2 m/s2 rms, respectively. A pattern of increasing percentage prevalence with increasing cumulative vibration dose was noticed. The subjects with a lifetime vibration dose of more than 20.1 m2 h3 s-4 (in scale) showed significantly higher prevalence rates for symptoms in the fingers and shoulders as compared with the control group. As occupational vibration exposure of traffic police motorcyclists might be considered a risk factor for the development of symptoms in the hand-arm system of the riders, its evaluation and control is needed for prevention methodology evolution.

Adult↗

PubMed1997

Clinical significance of bcl-2 gene expression in human breast cancer tissues.

The expression of estrogen receptor (ER) and bcl-2 (Bcl-2), an apoptosis protective oncogene, in normal and cancerous breast duct epithelia was immunohistochemically examined in fresh frozen tumor tissues from 142 Japanese breast cancer patients. The clinico-pathological characteristics and the disease free survival of the patients were analyzed. The expression of both the proteins was also observed in intraductal components of breast cancer. Although less than 1% of normal duct epithelia expressed ER, Bcl-2 was diffusely expressed. The expression of both these proteins in breast cancer significantly correlated with each other. Their expression significantly correlated negatively with tumor size but not with lymph node status. The papillo-tubular sub-type of invasive ductal carcinoma expressed Bcl-2 significantly more frequently than the solid-tubular sub-type. Patients with Bcl-2 expressing tumors survived without recurrence significantly more than those with tumors exhibiting reduced expression. Papillary-cribriform type intraductal components expressed both those proteins more often than the solid-comedo type.

Adult↗

PubMed1997

Constitutive activation of mitogen-activated protein kinase pathway in acute leukemia cells.

Mitogen-activated protein (MAP) kinase appears to be one of the key regulators of cell proliferation and differentiation. Very little, however, has been revealed as to how MAP kinase is involved in leukemogenesis. We have studied the activation of the MAP kinase pathway in 100 human primary leukemia cells including 73 acute myelogenous leukemias (AMLs). Forty acute leukemia samples (40% of the total), including 37 AML samples (51% of AML), showed activation of MAP kinase as revealed by the mobility shift of the phosphorylated form of the protein and by in vitro kinase assay. This activation was correlated with MAP kinase kinase activity in these cells. In contrast, none of 14 chronic myelogenous leukemia samples showed the activation of MAP kinase. These results suggest that the MAP kinase pathway is constitutively activated in a subset of primary acute leukemias, and thus indicate the possible role of the constitutively activated MAP kinase in leukemogenesis.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1997

Differential display analysis of murine collagen-induced arthritis: cloning of the cDNA-encoding murine ATPase inhibitor.

We used the differential display technique in order to detect a new gene involved in murine type II collagen-induced arthritis (CIA). In this study, we have identified a novel gene, IF1, whose expression level is increased during the natural course of CIA. Northern blot analyses suggest that IF1 is involved in the natural course of CIA but is not involved as a trigger of CIA. IF1 is considered to be the murine ATPase inhibitor gene for several reasons. First, IF1 shows an extremely high homology to the rat ATPase inhibitor; the highly conserved region between rat and bovine amino acid residues 22-45, which is the minimum sequence showing ATPase inhibitory activities, is also highly conserved in IF1. Second, IF1 possesses a histidine-rich region in the same area, which is thought to be important for regulation of mammalian inhibitors. Third, the tissue distribution of IF1 is very suggestive. The expression of IF1 was very strong in energetic organs such as the heart, brain and kidney, and the development of arthritis requires great amounts of ATP. As arthritis develops rapidly, the cellular ATP pool may be decreased. Before the ATP pool is exhausted, the ATPase inhibitor may serve as a brake for ATP hydrolysis. If the supply of free energy can be reduced, the inflammation of arthritis may in turn be restored. Our hypothesis is that the ATPase inhibitor is involved in regulating the inflammatory responses.

Amino Acid Sequence↗

PubMed1997

Isozyme selective alterations of the expression of cytochrome P450 during regeneration of male rat liver following partial hepatectomy.

1. During liver regeneration in the male rat, the metabolic activities of imipramine were differentially affected depending on the specific metabolic pathways. Imipramine N-demethylation was markedly reduced whereas 2-hydroxylation showed only a moderate reduction following partial hepatectomy. 2. A slight decline was observed in the hepatic microsomal content of CYP2D apoprotein, whereas a substantial decrease occurred in CYP2C11 content during liver regeneration. Since imipramine 2-hydroxylation and N-demethylation are mediated by CYP2D and 2C11 respectively, metabolic pathway-specific alterations in the activities of imipramine metabolism are explained by the isozyme selective alteration in the levels of CYPs in regenerating liver. 3. No significant effect of regeneration was observed on expression of CYP2B1 and 2E1 apoproteins. CYP3A2 apoprotein, one of the male-specific CYP isoforms, was significantly suppressed in regenerating liver showing a similar pattern of alteration to the levels of CYP2C11. The alteration pattern of the CYP1A1 level was different to the above with a moderate decline at the first day post-operation and a marked rebound thereafter. 4. In the partially hepatectomized male rate, no significant increase in androstenedione 5-alpha reductase activity, an activity predominant in the female rat, was detected. It is concluded that the pattern of alterations of hepatic oxidative metabolism during liver regeneration was not related to the functional feminization of the liver.

Androstenedione↗

PubMed1997

Rapidly destructive arthropathy of the hip in siblings.

A case of rapidly destructive arthropathy of the hip in male siblings aged 74 and 76 years is reported. Hip joints of the brothers were destroyed 12 and 4 months after the onset of symptoms, respectively. Results of clinical and laboratory examinations did not show any features of neuropathic, inflammatory, or septic arthropathy. Pathologically in both patients, osteoarthrotic changes with small foci of bone necrosis and nonspecific inflammation and moderate amount of hemosiderosis in the synovium were observed.

Aged↗

PubMed1997

Protooncogene expression in osteogenesis induced by bone morphogenetic protein.

In this study, changes in the expression of protooncogenes c-fos and c-myc messenger ribonucleic acid were investigated in mice after implantation of bone morphogenetic protein. The expression of c-fos showed a biphasic pattern. The first increase was observed on Day 1 with the aggregation of round cells. The second increase was observed on Day 7 with the appearance of chondroblasts. The amount of c-myc messenger ribonucleic acid showed the sustained high levels from Days 2 to 7. During this period, the proliferation of mesenchymal cells was histologically evident. After Day 11, the expression of c-fos and c-myc decreased and remained at low levels despite the progress in chondroosteogenesis. The protooncogenes c-fos and c-myc appear to increase before calcification in the process of bone morphogenetic protein induced bone and cartilage development.

Animals↗