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Biomedical subjects

H Kawamura

Publications and source records attributed to H Kawamura.

At least 91 records · Page 5Linked to original sources
PubMed1999

Acquisition of improved reference values for cesium, iodine, strontium, thorium, and uranium in selected NIST reference materials.

As part of a study on the ingestion and organ content of some trace elements of importance in radiological protection, additional work has been undertaken to acquire improved reference values for cesium, iodine, strontium, thorium, and uranium in four selected reference materials provided by the US National Institute of Standards and Technology. The materials are SRM-1548 Total Diet, SRM-1548a Typical Diet, SRM-1486 Bone Meal, and RM-8414 Bovine Muscle. A coordinated study was undertaken with the help of seven selected laboratories in five countries. Instrumental and radiochemical neutron activation analysis and inductively coupled plasma-mass spectrometry were the analytical main techniques used.

Animals↗
PubMed1999

Mesenteric venous thrombosis associated with protein C deficiency.

An 83-year-old man had gradually worsening abdominal pain and vomiting. Laparotomy revealed segmental intestinal infarction resulting from thrombosis in the superior mesenteric vein. Necrosed intestine was resected and anastomosis was performed successfully. The patient was anticoagulated with intravenous heparin and nafamostat mesilate followed by oral aspirin. He recovered rapidly. Blood chemistry revealed protein C deficiency, while protein S and antithrombin III levels were normal. Laboratory evaluation of these proteins may help define the cause of mesenteric venous thrombosis.

Abdominal Pain↗
PubMed1999

Long-term changes in clinical signs and symptoms and disc position and morphology in patients with nonreducing disc displacement in the temporomandibular joint.

PURPOSE: The purpose of this study was to examine disc position and configuration, as well as clinical findings, during the natural course of nonreducing disc displacement of the temporomandibular joint (TMJ). PATIENTS AND METHODS: The subjects were 21 patients (24 affected joints) for whom a diagnosis of anterior disc displacement without reduction in the TMJ had been made on arthrography, but who had received no treatment for more than 12 months. The disc position and configuration were examined at a mean follow-up of 27.1 months using magnetic resonance imaging. Clinical signs and symptoms were also examined. As a control, 30 joints in 15 persons who had no current or previous TMJ symptoms were studied. RESULTS: The patients' clinical signs and symptoms tended to be alleviated during the follow-up period. In all patients, the disc was displaced anteriorly on mouth closure, and it did not reduce into normal position during mouth opening at the follow-up, whereas normal disc position was found in all of the controls. In the patients, the disc deviated from the normal biconcave configuration found in all of the controls, frequently showing enlargement of the posterior band, even thickness, folding, and convex configurations in the follow-up magnetic resonance imaging. CONCLUSION: Disc displacement does not resolve, and continued disc deformity is common in the natural course of nonreducing disc displacement of the TMJ, although the clinical signs and symptoms tend to become alleviated.

Adolescent↗
PubMed1999

A new, all-inside technique for meniscus repair.

A new method for arthroscopic meniscal repair using sutures with multiple knots was developed, and its mechanical strength was evaluated. Sutures are passed arthroscopically through the torn meniscus using a needle with a cleft in its tip, and when the needle is withdrawn, knots are placed both in the meniscus and the joint capsule. Our method does not require additional skin incisions and can be performed for repair of posterior tears. Furthermore, this all-inside technique minimizes the risk of popliteal neurovascular injury. Biomechanical analysis using bovine menisci showed that the maximum frictional force between the suture and meniscus was greater than the maximum strength of a suture itself. Our method is simple and rapid, making it easy to insert multiple sutures to achieve adequate stability.

Animals↗
PubMed1999

Skeletal anchorage system for open-bite correction.

A skeletal anchorage system was developed for tooth movements. It consists of a titanium miniplate that is temporarily implanted in the maxilla or the mandible as an immobile anchorage. In this article, we introduce the skeletal anchorage system to intrude the lower molars in open-bite malocclusion and evaluate the results of treatment in two severe open-bite cases that underwent orthodontic treatment with the system. Titanium miniplates were fixed at the buccal cortical bone around the apical regions of the lower first and second molars on both the right and left sides. Elastic threads were used as a source of orthodontic force to reduce excessive molar height. The lower molars were intruded about 3 to 5 mm, and open-bite was significantly improved with little if any extrusion of the lower incisors. No serious side-effects were observed during the orthodontic treatment. The system was also very effective for controlling the cant and level of the occlusal plane during orthodontic open-bite correction.

Adolescent↗
PubMed1999

Involvement of p42/p44 MAP kinase in endothelin-1-induced interleukin-6 synthesis in osteoblast-like cells.

We previously reported that endothelin-1 induces synthesis of interleukin-6 (IL-6) via activation of protein kinase C in osteoblast-like MC3T3-E1 cells. In the present study, we further investigated whether p42/p44 mitogen-activated protein (MAP) kinase is involved in endothelin-1-induced IL-6 synthesis in these cells. Endothelin-1 stimulated p42/p44 MAP kinase activation in a dose-dependent manner in the range between 0.1 nmol/L and 0.1 micromol/L. PD98059, a specific inhibitor of the upstream kinase that activates p42/p44 MAP kinase, suppressed endothelin-1-induced IL-6 synthesis as well as endothelin-1-activated p42/p44 MAP kinase. Both p42/p44 MAP kinase activation and IL-6 synthesis induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C-activating phorbol ester, were reduced by PD98059. Calphostin C, a highly specific inhibitor of protein kinase C, suppressed endothelin-1-stimulated p42/p44 MAP kinase activation as well as endothelin-1-induced IL-6 synthesis. These results strongly suggest that protein kinase C-dependent p42/p44 MAP kinase activation is involved in endothelin-1-induced IL-6 synthesis in osteoblast-like cells.

Animals↗
PubMed1999

Mice with early onset of death (EOD) due to lupus glomerulonephritis.

Both MRL-lpr/lpr (lpr) and BXSB mice fall victim to autoimmune disease as a function of age. To combine their properties, brother-sister mating of (female lpr x male BXSB)F1 mice was done. Mice for mating were selected according to indicators of early onset of glomerulonephritis and subsequent early death (i.e., EOD). This mating was continued for more than 16 generations. The EOD mice thus established had homozygous H-2k/k, lpr/lpr, and possible yaa/- (in the case of males). The average life span of males was 83 days while that of females was 126 days. After 12 weeks of age, the majority (> 80%) of male EOD mice were characterized by the abnormality of urine due to glomerulonephritis. We then characterized how glomerulonephritis was evoked, especially in terms of expanding lymphocyte subsets in various immune organs. Similar to the case of parental lpr mice, the major expanding cells were CD4-8-B220+ TCRint cells in the immune organs and kidney. In addition, myeloid cells were found to infiltrate the kidney. This massive infiltration of both TCRint cells and myeloid cells might be responsible for the onset of acute glomerulonephritis. Even after more than 50 generations, these EOD mice still carry both lpr and yaa genes. These results suggest that EOD mice might be a very useful tool for the study of acute lupus glomerulonephritis which is evoked by the genetic abnormalities.

Acute Disease↗
PubMed1999

Occlusal contact area, occlusal pressure, bite force, and masticatory efficiency in patients with anterior disc displacement of the temporomandibular joint.

The occlusal contact area, occlusal pressure, bite force, and masticatory efficiency were measured in 48 patients with anterior disc displacement (ADD) of the temporomandibular joint (TMJ). The results were compared with those of 30 normal controls without TMJ dysfunction. The values of occlusal contact area, bite force, and masticatory efficiency measured in patients with ADD were significantly smaller than those measured in the controls, although there was no difference in occlusal pressure between the two groups. The results of the measurements of 22 patients with ADD with reduction were also compared with those of 26 patients with ADD without reduction. There was no difference in any measurement between these patients subgroups. The analysis of occlusal contact area, bite force, and masticatory efficiency appeared to be useful methods in documenting the fact that masticatory function was impaired in patients with ADD of the TMJ.

Adenosine Triphosphate↗
PubMed1999

Endothelin-1 stimulates heat shock protein 27 induction in osteoblasts: involvement of p38 MAP kinase.

We previously reported that endothelin-1 (ET-1) activates p42/p44 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells and consequently induces synthesis of interleukin-6. In the present study, we investigated the effect of ET-1 on the induction of heat shock protein 27 (HSP 27) in MC3T3-E1 cells. ET-1 time and dose dependently stimulated HSP 27 accumulation. ET-1 induced an increase in the levels of mRNA for HSP 27. Both staurosporine and calphostin C, inhibitors of protein kinase C (PKC), suppressed the ET-1-induced HSP 27 accumulation. 12-O-tetradecanoylphorbol 13-acetate (TPA), a PKC activator, induced the HSP 27 accumulation and the expression of mRNA for HSP 27. The ET-1-stimulated HSP 27 accumulation was reduced in PKC-downregulated MC3T3-E1 cells. The HSP 27 accumulation by ET-1 was not suppressed by PD-98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. ET-1 or TPA induced the phosphorylation of p38 MAP kinase. SB-203580, an inhibitor of p38 MAP kinase, reduced the ET-1-stimulated HSP 27 accumulation. Calphostin C and U-73122, a phospholipase C inhibitor, suppressed the ET-1-induced phosphorylation of p38 MAP kinase. U-73122 and propranolol, a phosphatidic acid phosphohydrolase inhibitor, reduced the ET-1-stimulated HSP 27 accumulation. SB-203580 suppressed the ET-1-stimulated increase in the mRNA levels for HSP 27. These results strongly suggest that ET-1 stimulates HSP 27 induction in osteoblasts and that p38 MAP kinase activation is involved in the HSP 27 induction.

Animals↗
PubMed1999

The incidence and development of periarteritis nodosa in testicular arterioles and mesenteric arteries of spontaneously hypertensive rats.

We sought to clarify the incidence, vessel-size and age distribution of periarteritis nodosa in rats occurring as a vascular lesion in malignant hypertension. Stroke-prone spontaneously hypertensive and stroke-resistant spontaneously hypertensive rat strains were studied, as well as Wistar-Kyoto control rats. Mesenteric arteries and testicular arteries were examined histologically. Additionally, electron microscopy investigation was carried out on one stroke-prone hypertensive rat and one control. Periarteritis nodosa lesions were present in testicular arterioles in 57.1%, and mesenteric arteries in 28.6%, of stroke-prone hypertensive rats aged 9.5 mo. Lesion incidence at these sites was 100% and 60% respectively in 10 stroke-prone rats aged 15.5 mo, and 42.9% and 28.6% in stroke-resistant hypertensive rats aged 22.5 mo. In contrast, the incidence rate was 0% at both sites in stroke-resistant hypertensive rats aged 8 or 14.5 mo, and in control rats aged 9.5 or 25 mo. In stroke-prone rats, arteritis lesion counts (mean+/-SD) in testicular sections were 11.6+/-17 at age 9.5 mo and 96.3+/-60.9 at age 15.5 mo. In individual lesion scoring, arteritis was more severe in mesenteric arteries than in testicular arterioles. For arteriolar lesion distribution patterns in testicular sections, partial peripheral, partial peripheral plus central, and circumferential patterns were all noted. In conclusion, periarteritis nodosa in hypertensive stroke-prone rats occurs earlier in testicular arterioles, but attains greater severity in the mesenteric artery.

Animals↗
PubMed1999

Vascular and stromal changes in irradiated and recovering rat thymus.

To analyze the mechanisms responsible for thymocyte proliferation, maturation and migration in the thymus, the rat thymus just after, and recovering from irradiation was studied morphologically. The vascular structures of the rat thymus after a radiation dose of 6 Gy were found to be destroyed on day 3, but had recovered to almost normal by day 7, suggesting that the abrupt recovery of thymus structure after irradiation was due primarily to this change in vascular structure. Furthermore, the epithelial tissues in the thymic cortex appeared to contribute to this abrupt proliferation, and possibly to the abrupt maturation of thymocytes, while medullary epithelial tissues remained sparse and appeared inactive for a relatively long period. These findings are considered important for understanding the interrelationship between thymic epithelial cells and thymocytes with respect to thymocyte proliferation, maturation and migration.

Animals↗
PubMed1999

A new mouse model of spontaneous diabetes derived from ddY strain.

By the selective breeding of obese male mice of the ddY strain and using indices of the heavy body weight and appearance of urinary glucose, we established two inbred strains in 1992: one with obesity and urinary glucose (Tsumura, Suzuki, Obese Diabetes: TSOD) and the other without them (Tsumura, Suzuki, Non Obesity: TSNO). The male TSOD mice constantly showed signs of obesity and urinary glucose with increases in food and water intake, body weight and some fat weight. The body mass index (BMI) clearly showed moderate obesity. Increases in the levels of diabetic blood parameters (glucose, insulin and lipids) were also found in males, in which the levels of blood glucose and insulin were high to the ages past the growth peak. In the histological studies, pancreatic islets of the TSOD males were found hypertrophic without any signs of insulitis or fibrous formation. Among these diabetic characteristics, some of which were similar to the reported models of non-insulin-dependent diabetes mellitus (NIDDM), the stable appearances of the hyperglycemia, the hyperinsulinemia and the hypertrophy of pancreatic islets to the ages past the growth peak were the prominent features. In these respect the TSOD mouse may be a useful model for researching the mechanisms of human diabetes and its complications.

Animals↗
PubMed1999

[Werner's syndrome associated with progressive subcortical vascular encephalopathy of the Binswanger type].

A 56-year-old woman with Werner's syndrome was admitted to our hospital because of intractable foot ulcer and malnutrition. She presented dementia consisting of childish behaviour, loss of intelligence, and severe amnesia. Brain CT revealed diffuse periventricular low density areas, and brain MRI also disclosed periventricular high intensity areas under T2-intensified conditions. These findings gave a diagnosis of progressive subcortical vascular encephalopathy of the Binswanger type, which seemed to be the cause of her dementia. She finally died of heart failure due to acute myocardial infarction. Mild to moderate demyelinization was found in the subcortical area of the autopsied cerebrum, confirming the clinical diagnosis. Generalized atherosclerosis characteristic of Werner's syndrome may have predisposed this patient to Binswanger's encephalopathy.

Brain↗
PubMed1999

[Two cases of testicular infarction: the usefulness of enhanced MRI for preoperative diagnosis].

The differential diagnosis in acute scrotum, particularly torsion of spermatic cord and epididymitis, is sometimes difficult. An erroneous diagnosis may result in unnecessary and improper treatment. We report two cases of testicular infarction including torsion of spermatic cord, preoperatively diagnosed by enhanced magnetic resonance imaging (MRI). Case 1: A 16-year-old boy presented with a 3-day history of left scrotal swelling and left lower abdominal pain. He had fever and leukocytosis. Antibiotics for 2 days failed to relieve the symptoms. Enhanced MRI showed absence of blood flow in the left testis. Scrotal exploration revealed hemorrhage and necrosis in the left testis. Left orchiectomy and right orchiopexy were performed. Case 2: A 12-year-old boy visited with scrotal swelling and fever 30 hours after an acute onset of left scrotal pain. Enhanced MRI showed absence of blood flow in the left testis. Exploration revealed left necrotic testis with torsion of spermatic cord. Left orchiectomy and right orchiopexy were performed. Our two cases suggested that enhanced MRI, by which the intratesticular blood flow can be evaluated, may be useful for the diagnosis of testicular infarction.

Adolescent↗
PubMed1999

Restoring normal gait after limb salvage procedures in malignant bone tumours of the knee.

Eleven patients exhibiting decreased strength of knee extension following wide resection and prosthetic reconstruction for malignant bone tumors of the knee performed gait exercises with compensatory muscle training. Two patients whose knee extension strength was assessed as manual muscle test (MMT) grade 4 were able to develop a gait with double knee action and to maneuver stairs, step-by-step, due to compensation by the gluteus maximus, biceps femoris, and gastrocnemius muscles. Four patients whose knee extension strength was less than MMT grade 4, and whose ankle dorsal and plantar flexion was MMT grade 4 or higher, acquired the ability to go up and down stairs step-by-step, although their gait pattern was a knee-extended gait. Electromyographic studies demonstrated continuous discharges of the gluteus maximus, biceps femoris, and gastrocnemius muscles during the stance phase as compensation for decreased strength in knee extension.

Adolescent↗
PubMed1999

Disc position and morphology in patients with nonreducing disc displacement treated by injection of sodium hyaluronate.

Disc position and morphology were examined in 21 patients (22 joints) with nonreducing disc displacement of the temporomandibular joint (TMJ) at more than 12 months after undergoing injection of sodium hyaluronate into the superior joint space. The patients' clinical signs and symptoms improved during the follow-up period. In all patients, the disc was displaced anteriorly on mouth closure and did not reduce into the normal position during mouth opening at follow-up, whereas a normal disc position was found in all the controls. In the patients, the disc deviated from the normal biconcave configuration found in all of the controls on the follow-up magnetic resonance imaging (MRI). Disc displacement apparently is persistent and continued disc deformity common in patients, although the clinical signs and symptoms improved.

Adolescent↗