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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 1,045 records · Page 58Linked to original sources
PubMed1993

[Surgical treatment of myasthenia gravis in patients with thymoma].

During the 18 years period from 1972 to 1990 fifty-two patients with thymoma, including 13 with thymoma and myasthenia gravis (MG), underwent surgical treatment in our hospital. During the same period 27 patients without thymoma underwent surgical intervention for MG. These patients were assessed from the clinical manifestations, clinical effects for MG, and prognosis. The improved effects of surgery for MG with or without thymoma could be yearly obtained after operation. Palliation and remission rates of the 10 patients of MG with thymoma, excluded postthymectomy MG, were very poor in comparison with that of the 27 patients of MG without thymoma. Further more, the prognosis of the 13 patients of thymoma with MG was worse than that of 39 patients of thymoma without MG. The association of thymoma and progressive severity of disease related closely the influence of delayed response to surgical intervention and prognosis. In conclusion, aggressive surgical resection followed by chemo-radiotherapy was the best treatment for the invasive thymoma. Postoperative intensive care for MG crisis and recurrence of thymoma improved the effect to surgical intervention and revealed the good prognosis.

Adolescent↗
PubMed1993

Transforming growth factor-beta protein and mRNA in glomeruli in normal and diseased human kidneys.

BACKGROUND: Evidence indicates a key role for transforming growth factor-beta (TGF-beta) in the accumulation of pathologic extracellular matrix in experimental glomerular injury. The aim of this study was to elucidate the expression of TGF-beta and its role in human glomerulonephritis. EXPERIMENTAL DESIGN: Expression of TGF-beta 1 in normal and diseased human kidneys was examined by immunohistochemical staining with two antibodies (Ab1 and Ab2), and by in situ hybridization with an oligonucleotide probe. RESULTS: Staining with Ab1, which mainly recognizes mature TGF-beta 1 and the latency-associated peptide (LAP) of natural TGF-beta 1, was linearly positive along the glomerular basement membrane (GBM) and weakly so in the mesangium of normal tissues and those of various glomerular diseases which were pretreated with acid-urea to unmask a hidden epitope. Ab2, which reacts mainly with TGF-beta-LAP, bound to the mesangium and sclerotic areas of the tissues untreated with acid-urea. Immunoelectron microscopy showed that Ab1 was localized to the GBM and the mesangial matrix, and that Ab2 was distributed in subepithelial, or mesangial/paramesangial electron-dense deposits. The presence of mature TGF-beta 1 and TGF-beta-LAP in normal kidneys was confirmed by immunoblotting using guanidine-extracted fractions of glomeruli and GBM isolated from normal human kidneys. Mesangial staining of TGF-beta 1 with Ab2 was significantly correlated with the mesangial matrix increase in mesangial proliferative types of nephritis. In situ hybridization revealed TGF-beta 1 mRNA expression in glomerular cells. Cells with positive mRNA signals were evident in glomeruli that were increased in both mesangial cells and TGF-beta 1 protein expression. The glomerular cells with positive signals were numerous, compared with the number of infiltrating monocyte-macrophages identified with a monoclonal antibody. CONCLUSIONS: These results indicate that mature TGF-beta and TGF-beta-LAP are localized in association with the matrix components of GBM or mesangium, and with immune deposits in human glomeruli. Glomerular expression of TGF-beta is enhanced in human glomerular diseases, and may contribute to the mesangial matrix increase.

Adolescent↗
PubMed1993

[The long-term follow-up study of Japanese patients with ulcerative colitis].

To elucidate the long-term outcome of the ulcerative colitis we analyzed 124 patients suffering for more than 10 years concerning the long-term prognosis, cumulative rate of colectomy, cumulative risk of cancer development and cumulative survival rate. Long-term prognosis were divided to three categories as good, fair and poor, according to present disease activities, social availability and subjective judgement. One hundred and twenty four patients were divided to 66 patients with good prognosis, 27 fair and 31 poor (2:1:1). The rate of patients having active disease at each year were followed-up annually for 10 years according to final three categories of the prognosis. The serial curve of annual rate of having active disease of the patients with poor prognosis was the highest, fair prognosis the second, good prognosis the lowest. The factors affecting the final prognosis were the period before initiation of proper treatment, the severity of the first attack or the elder age (> 40 year old) at the first attack. Twenty six patients were undergone colectomy in relation to ulcerative colitis. The cumulative colectomy rate was 16.5% at 10 years and 38.5% at 15 years after the onset. Malignant disease or severe dysplasia of the colon developed in 4 patients 10 to 14 years after the onset. Cumulative survival rate was equal to the expected survival curve during 16 years. The main causes of death were intracranial hemorrhage and colorectal malignant disease.

Adolescent↗
PubMed1993

Cytotoxicity of unstimulated and thrombin-activated platelets to human tumour cells.

Platelet cytotoxicity was examined in vitro using various tumour cell lines as target cells. Thrombin-activated platelets as well as unstimulated platelets exerted a cytotoxic effect on some tumour cell lines including K562, KU812, LU99A and KG1, but other tumour cell lines including U937, MIA PaCa-2 and MOLT-4 were completely insensitive to this effect. Electron microscopic examinations showed that unstimulated platelets adhered to target K562 cells but thrombin-activated platelets did not. Morphological changes of K562 cells induced by unstimulated and thrombin-activated platelets were indistinguishable. When platelets and K562 cells were co-cultured in the same vessel but were prevented from coming into direct cell-to-cell contact by means of a membrane barrier, cytotoxicity of unstimulated platelets was completely blocked but that of thrombin-activated platelets was still detectable. However, no cytotoxic activity to K562 cells was detected in the supernatants obtained after stimulation of platelets with either target cells or thrombin for 4 hr. Extracellular Ca2+ ion was not required for the platelet-mediated cytotoxicity. Esterase inhibitors SBTI and TPCK had no effect on the formation of platelet-target cell adhesion but inhibited the cytotoxicity of unstimulated platelets. In contrast, the inhibitors had no effect on the cytotoxic activity of thrombin-activated platelets. These results suggest that direct contact between platelets and target cells is essential for unstimulated platelets but not for thrombin-activated platelets to exert cytotoxicity and that some esterases play a role in the cytotoxic process of unstimulated platelets. They also provide evidence that some cytotoxic effectors are soluble and easily inactivated factors liberated by activated platelets. Our findings indicate that platelets may be one of the cytotoxic effector cells against certain neoplasia.

Blood Platelets↗
PubMed1993

Biomechanical study of temporomandibular joint on its form and function. Part I: Condyle morphology in frontal section.

In this study the mechanisms controlling the biomechanical relationship between form and function in the temporomanidbular joints were investigated using two-dimensional finite element analysis and optimization theory. Factors investigated included morphology and occlusion, the latter being an important attribute of this system. Results indicate that change in frontal condyle head morphology was closely related to the occlusion condition.

Biomechanical Phenomena↗
PubMed1992

Reactive proliferation of astrocytes studied by immunohistochemistry for proliferating cell nuclear antigen.

Astrocyte proliferation in the stab-wounded cerebral cortex of mice was studied using double immunohistochemistry for proliferating cell nuclear antigen (PCNA) and glial fibrillary acidic protein (GFAP). The number of GFAP-positive astrocytes increased markedly from day 0.5 to day 3 after stab wounding. Some GFAP-positive astrocytes in the immediate vicinity of the wound were found to be positive for PCNA. However, the maximum number of these double positive astrocytes was only 5-6% of the number of GFAP-positive astrocytes. This maximum value was observed on days 2.5 and 3. The present study revealed that astrocytes are able to reactively express PCNA, an intrinsic marker of DNA replication. On the other hand, it is suggested that the proliferation of astrocytes in the wounded cerebral cortex is limited, in contrast with their marked reactive up-regulation of GFAP.

Animals↗
PubMed1992

Nerve growth factor suppresses apoptosis of murine neutrophils.

We investigated inhibitory activity of nerve growth factor (NGF) on apoptosis of murine peritoneal exudate neutrophils. During culture for 9 h, apoptotic cells were identified by morphological changes under a light microscope: nuclear pyknosis and chromatin condensation with or without cytoplasmic vacuolation. The apoptotic state was confirmed by DNA fragmentation indicating the endogenous endonuclease activation. When neutrophils were incubated in the presence of NGF, the proportion of cells with the morphological changes was decreased in a dose-dependent manner, and the development of the characteristic DNA fragmentation was restricted. The apoptosis-suppressing activity of NGF was abolished by the addition of anti-NGF monoclonal antibody. These results suggest that NGF may suppress neutrophil apoptosis by preventing the endogenous endonuclease activation.

Animals↗
PubMed1992

[Evaluation of aortic distensibility using cine MR imaging].

Regional aortic distensibility was measured noninvasively using cine MR imaging to determine whether it correlates with aging or risk of coronary artery disease (CAD). Twenty-two patients with CAD confirmed by angiography and 33 without CAD underwent cine MR imaging. Thirty-two sequential images were obtained in one cardiac cycle. The cross sectional area of the descending thoracic aorta was measured on both diastolic (A) and systolic (A') images. Aortic distensibility (A.D.) was calculated from the following equation: A.D. = (A'-A)/A/delta P. (delta P represents pulse pressure). Results of a simple regression analysis showed that decreased regional aortic distensibility was significantly correlated with the age of the patients (r = -0.762, p less than 0.005). In addition, the parameter was lower in patients with CAD than those without CAD (p less than 0.05). In conclusion, regional aortic distensibility derived from cine MR imaging is a useful parameter to evaluate not only aging but also pathological atherosclerosis of the aorta. In addition, this parameter might have some potential to evaluate the prediction of CAD in patients with normal serum cholesterol.

Adolescent↗
PubMed1992

Effects of the N-methyl-D-aspartate antagonists on the rise in [Ca2+]i following depolarization in aged rat brain synaptosomes.

The effects of non-competitive NMDA antagonists, MK-801 and dextrorphan in relation to the rise in intracellular Ca2+ concentrations ([Ca2+]i) after stimulation with 15 mM K+ in whole brain synaptosomes from young (3 months old) and aged (24 months old) Fisher344 rats were examined. A fluorescent chelating agent, Rhod-2, was employed to monitor any alterations of K(+)-evoked [Ca2+]i. In young rats, the rise in [Ca2+]i following depolarization was affected by neither dextrorphan (1, 10, 100 microM) nor MK-801 (0.1, 1, 10 microM), while in aged rats, 1 microM dextrorphan and 0.1 microM MK-801 brought about a significant increase in [Ca2+]i following depolarization. In low Mg2+ medium, 10 microM MK-801 and 100 microM dextrorphan significantly inhibited the rise in [Ca2+]i after stimulation with 15 mM K+ in young rats, while neither dextrorphan nor MK-801 could affect the rise in [Ca2+]i significantly in aged rats. When 100 microM NMDA was applied in a medium containing 1.2 mM Mg2+, the rise in [Ca2+]i following depolarization was slightly inhibited by 1 microM MK-801 in young rats, but it was not inhibited significantly by dextrorphan. In aged rats, both 100 microM dextrorphan and 10 microM MK-801 strongly inhibited the rise in [Ca2+]i following depolarization in the presence of 100 microM NMDA. Instead of NMDA, when 100 microM alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), a non-NMDA receptor agonist, was applied, dextrorphan did not inhibit the rise in [Ca2+]i. In low Mg2+ medium, 100 microM NMDA potentiated the inhibitory effect of 10 microM dextrorphan in young rats, while 100 microM dextrorphan or MK-801 did not show any further inhibition by adding 100 microM NMDA. The addition of 100 microM AMPA did not affect the effect of dextrorphan in a low Mg2+ medium in young rats. These results suggest that NMDA antagonist-mediated [Ca2+]i homeostatic system may alter through aging. In addition, the findings that NMDA potentiated the inhibitory effect of NMDA antagonist, which being further potentiated by aging or lowered extrasynaptosomal Mg2+, indicate the possibility that the Mg2+ block to NMDA receptors might be attenuated through aging.

Aging↗
PubMed1992

The facilitating and suppressing effects of delta 9-tetrahydrocannabinol on the rise in intrasynaptosomal Ca2+ concentration in rats.

The effects of delta 9-tetrahydrocannabinol (delta 9-THC) on the rise in intracellular Ca2+ concentrations ([Ca2+]i) after stimulation with 15 mM or 29 mM K+ in rat whole brain synaptosomes were examined. A fluorescent chelating agent, Rhod-2, was employed to monitor any alterations of K(+)-evoked [Ca2+]i. Pretreatment with 10(-10) M delta 9-THC for 3 min enhanced K(+)-evoked [Ca2+]i significantly, while 10(-9), 10(-8) or 5 x 10(-8) M delta 9-THC significantly inhibited the K(+)-evoked [Ca2+]i. These results suggest that delta 9-THC had a biphasic effect on the K(+)-evoked Ca2+ response in rat brain synaptosomes.

Animals↗
PubMed1992

Experimental atrophic rhinitis in 2 and 4 month old pigs infected sequentially with Bordetella bronchiseptica and toxigenic type D Pasteurella multocida.

Experimental infections with Bordetella bronchiseptica and/or toxigenic type D Pasteurella multocida were studied in 2- and 4-month-old primary specific-pathogen-free pigs. None of the 2-month-old pigs inoculated with B. bronchiseptica or P. multocida alone developed turbinate atrophy. All the pigs inoculated with B. bronchiseptica (10(7) CFU/head) and P. multocida (10(9) CFU/head for 5 consecutive days) together, however, developed clinical and post-mortem signs of atrophic rhinitis (AR) similar to the naturally occurring disease. Slight to severe turbinate atrophy was observed in the 4-month-old pigs inoculated with B. bronchiseptica and P. multocida (at the same concentration as above) at necropsy.

Animals↗
PubMed1992

[Percutaneous transluminal angioplasty of dialysis access shunts].

Sixteen balloon angioplasties were performed in 10 patients with upper-extremity dialysis access shunts. The initial success rate was 80% (12/15). Of the initial successes, 58% (7/12) were patent at six months and 13% (1/8) at one year. In nine cases, repeat PTA was necessary. The mean interval of patency was about four months. The longest interval was two and a half years. The complication of thrombosis of the loop shunt during PTA was successfully treated by fibrinolytic therapy.

Adult↗
PubMed1992

Molecular cloning and expression of chicken C-terminal Src kinase: lack of stable association with c-Src protein.

Cloning and sequencing of chicken C-terminal Src kinase (CSK), a tyrosine kinase that phosphorylates the regulatory C-terminal tyrosine residue present on cytoplasmic tyrosine kinases of the Src family, demonstrated a high degree of interspecies conservation as well as src homology 2 and 3 domains N-terminal to the kinase domain. The lack of autophosphorylation sites distinguishes CSK from other tyrosine kinases. CSK is unique and does not belong to a gene family, suggesting that it may phosphorylate other members of the Src family of tyrosine kinases in addition to c-Src. Since complex formation between c-Src and CSK seemed a likely regulatory step in the control of c-Src kinase activity, such an association was investigated by immunoprecipitation and Western blotting as well as intracellular localization studies. Although some portions of CSK were found in a membrane fraction, no complex formation between CSK and c-Src was observed, suggesting that the src homology 2 domain of CSK does not play a role in the direct interaction of c-Src.

Amino Acid Sequence↗
PubMed1992

Myelopathy due to large veins draining recurrent spontaneous caroticocavernous fistula.

A 45-year-old woman developed a myelopathy 9 years after a spontaneous left caroticocavernous fistula (CCF) was treated by a trapping procedure, with clipping distal to the fistula and ligation of the common carotid artery. Spinal MRI and vertebral angiography revealed recurrence of the CCF and gigantic tortuous veins draining through the brain stem down to the midcervical spinal cord. The abnormal veins and myelopathy disappeared after surgical closure of the CCF.

Arteriovenous Fistula↗