Biomedical subjects
Publications and source records attributed to Y Nishiura.
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We analyze the effect of additive periodic stimuli in one-dimensional FitzHugh-Nagumo equations in an excitable regime. With a suitable stimulus interval, the suppression of the pulse propagation occurs in some parameter regime. This propagation failure comes from the formation of the "death spot" where successive pulses annihilate. In the parameter regime where the solitary pulse cannot propagate in space stably, however, periodic stimuli cause a propagation of envelope of a traveling pulse under a "resonance" condition, i.e., the pulse at the leading edge disappears successively, however, an envelope is formed and propagates with keeping its shape.
Prolactin (PRL) is a single-chain polypeptide hormone that is generally secreted from prolactin cells of the anterior pituitary gland into the blood circulation. However, recent studies indicate that the gene expression of prolactin is ectopic in several tissues across several species. These studies found that lymphocytes also produce PRL, which is involved in the immunoregulatory system. Here, we searched for PRL messenger ribonucleic acid (mRNA), using the reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting in the spleens of mice at various growth stages. We also localized mouse prolactin (mPRL) and its mRNA in the spleens of 30- and 60-day-old mice by immunohistochemistry and in situ hybridization respectively. The mPRL gene was expressed in all spleen samples at 0-60 days postpartum. We localized mPRL mRNA in the sheathed artery, periarterial lymphatic sheath and the marginal zone of the spleen. Moreover, we detected mPRL in essentially the same area as its mRNA. Furthermore, we performed double-fluorescence immunohistochemical staining for mPRL and mouse CD4 that is specifically produced in helper T cells, or for mPRL and mouse CD19 or CD40 specified B cells. We colocalized mPRL immunoreactivity only in some CD4-immunopositive cells. These results clearly suggest that T cells synthesize mPRL in the mouse spleen.
Human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) is characterized by chronic inflammation of the spinal cord. The exact mechanisms that enhance the development of chronic myelopathy remain to be determined. One such mechanism could be an altered response of peripheral blood CD4(+) T lymphocytes to apoptotic stimuli. We examined the sensitivity of these cells to apoptosis in HAM patients and control. Apoptosis was induced by etoposide, which induces mitochondria-dependent apoptosis through the release of cytochrome c from the mitochondria. The percentage of apoptotic cells that expressed hypodiploid DNA among etoposide-treated CD4(+) T lymphocytes was significantly lower in HAM patients than in the control. Western blot analysis of cell lysates derived from CD4(+) T lymphocytes demonstrated that the expression level of Bcl-xL protein was significantly higher in HAM patients than in the control. Our results indicate that peripheral blood CD4(+) T lymphocytes of HAM patients are resistant to apoptosis triggered through mitochondrial death pathway through upregulation of expression of anti-apoptotic protein, Bcl-xL. This phenomenon might contribute to the prolongation and perpetuation of the chronic inflammatory process in the spinal cord of HAM patients.
Effects of hyperbaric oxygen treatment (HBO) on nerve regeneration in acellular nerve and muscle grafts were investigated in rats. Nerve and muscle grafts were made acellular by freeze-thawing and the obtained grafts were used to bridge a 10-mm gap in the sciatic nerve on the left and right sides, respectively. Rats were treated with HBO (100% oxygen for 90 minutes at 2.5 atmospheres absolute pressure ATA) twice a day for 7 days. Axonal outgrowth, Schwann cell migration and invasion of macrophages were examined 10 days after the graft procedure by staining neurofilaments, S-100 proteins and the macrophage antibodies ED1 and ED2, respectively. Axonal outgrowth and Schwann cell migration in acellular nerve grafts were superior to that found in the acellular muscle grafts. However, there was no difference between HBO-treated and nontreated rats in acellular nerve grafts. Such a difference was found in acellular muscle grafts concerning both axonal outgrowth and Schwann cell migration from the proximal nerve end. No differences in the content of macrophages or neovascularization (alkaline phosphatase staining) in either of the grafts and treatments were seen. It is concluded that there is a differential effect of HBO-treatment in acellular nerve and muscle grafts and that HBO-treatment has no effect on the regeneration process in acellular nerve grafts, in contrast to fresh cellular nerve grafts where a beneficial effect has previously been reported.
We studied the effect of hyperbaric oxygen treatment on axonal outgrowth in grafts of sciatic nerves in 40 rats. The sciatic nerve was transsected and a 10 mm long segment from the opposite side was immediately sutured in as a nerve graft. Postoperatively 17 animals were treated with 100% oxygen at 3.2 atmospheres absolute pressure for 45 minutes and the treatment was repeated at four and eight hours postoperatively and then every eight hours until evaluation. At seven days the axonal outgrowth was evaluated by immunohistochemical staining of neurofilaments in the nerve grafts. The axonal outgrowth was significantly longer in animals treated with hyperbaric oxygen. We conclude that hyperbaric oxygen can improve nerve regeneration in sciatic nerve grafts in rats.
Although the principal neuropathological feature of human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) is chronic inflammation of the spinal cord, characterized by perivascular cuffing of mononuclear cells accompanied by parenchymal lymphocytic infiltration, the precise mechanisms by which HTLV-I infection causes chronic inflammation of the spinal cord are still obscure. In patients with HAM, peripheral blood CD4(+)T lymphocytes, particularly HTLV-I-infected CD4(+)T lymphocytes, have increased adherent activity to endothelial cells and transmigrating activity through basement membranes. In addition, the profile of cytokine expression suggests increased numbers of Th1 cells in peripheral blood CD4(+)T lymphocytes of patients with HAM. These findings strongly suggest that immune deviation toward Th1, which might be based on high viral load of HTLV-I, plays an important role in tissue damage in the central nervous system of patients with HAM. We herein emphasize the importance of activated Th1 cells as the first trigger in the immunopathogenesis of HAM.
In order to elucidate the underlying mechanisms of a discordant case with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in monozygotic twins, we investigated HTLV-I tax sequences of 10 - 18 polymerase chain reaction-based clones each derived from peripheral blood mononuclear cells of the twins as well as their infected mother and an elder brother who also suffered from HAM/TSP. Sequence comparison revealed that three of the infected individuals including a twin with HAM/TSP shared the consensus tax sequence identical to the reference, ATK-1, but that of another healthy twin was different at five nucleotide positions including three nonsynonymous changes from ATK-1. This finding strongly suggested that different HTLV-I strains infected the monozygotic twins and the difference in infected proviral sequences determined the discordant clinical outcomes. Transfection and subsequent reporter assays failed to show a significant difference in transactivation activity on HTLV-I LTR and NF-kappaB elements between the products of the two sequences. Two HAM/TSP patients (a twin and elder brother) among three members infected with the ATK-1 type virus shared a paternal HLA allele which was absent in the healthy individual (mother). Genetic analysis of sequence variation in the tax sequences of the discordant twins showed that the Dn/Ds ratio was high in the healthy twin but low in the twin with HAM/TSP, implying the presence of more intense selection forces in the carrier. Our findings strongly suggested that a particular combination of HTLV-I strains with an HLA genotype would be a risk for HAM/TSP.
A 15-year-old woman with a history of transient dysarthria two years before, suddenly developed weakness of right upper extremity, right facial palsy, and dysarthria. She was admitted to our hospital on the third day. She had no hypertension, heart murmur and oedema. On neurological examination, she had mild right hemiparesis including face muscles and mild dysarthria. The right knee jerk was brisk with no Babinski's sign. Ataxia and sensory disturbance were not present. T2-weighted MRI showed a hyperintensity at the posterior limb of the left internal capsule. Cerebral angiography was unremarkable. Ultracardiography and 24-hour electrocardiography were normal. Laboratory data revealed no inflammatory findings, liver dysfunction, hyperglycemia and hyperlipidemia. Antinuclear and anticardiolipin antibodies were negative. Prothrombin time was normal, but activated partial thromboplastin time was slightly prolonged (35.4 sec, normal 25.2-34.4). Protein C, protein S and antithrombin III were normal. Heparin cofactor II (HC II) activity was decreased (44%) with normal HC II antigen (79%) and so she was diagnosed as heparin cofactor II deficiency type II (heparin cofactor II abnormality). Her father manifesting thromboangitis obliterans also had low HC II activity with normal HC II antigen. However, on her genetic analysis, we didn't detect any mutations in the coding region of HC II gene. Until now she has no recurrence of cerebrovascular attacks. On the basis of these results, we suspect that HC II deficiency was a possible risk factor of cerebral infarction in this case because she was so young and had no general risk factors except for HC II. No stroke associated with HC II deficiency type II has been reported up to date. This case is worth considering etiologies of juvenile cerebral infarction.
The prognostic value of hypercapnia and/or pulmonary hypertension differs in patients with sequela of pulmonary tuberculosis (TBseq) and those with chronic obstructive pulmonary disease (COPD) who are receiving home oxygen therapy (HOT). In an attempt to identify the factors, if any, that might explain this difference, we first compared nutritional status, respiratory function test results, dyspnea indexes, and other data for hypercapnic patients (PaCO2 > or = 45 Torr) and normocapnic patients (PaCO2 < 45 Torr) receiving HOT. Second, we examined the relationship between the degree of pulmonary hypertension and several respiratory function parameters for patients in each disease category. In 44 patients with TBseq, nutritional status estimated by body mass index and serum albumin was significantly better in the hypercapnic patients than in the normocapnic patients. However, this difference was not observed in 37 patients with COPD. In 30 patients with TBseq, the degree of pulmonary hypertension correlated significantly only with PaO2; in 32 patients with COPD, however, significant correlations were observed not only with PaO2 but also with PaCO2, %VC, and FEV1. These differences distinguishing groups of patients with the 2 diseases may provide an explanatory basis for the difference in prognostic value of hypercapnia and/or pulmonary hypertension in patients receiving HOT.
Using a 51Cr release assay, we investigated Fas-mediated cytotoxicity of peripheral blood CD4+ T cells of patients with human T-lymphotropic virus type-I (HTLV-I)-associated myelopathy (HAM) against T98G, a glioblastoma cell line which expresses Fas. Cytotoxic activity of CD4+ T cells against T98G was significantly higher in HAM patients than in controls. Moreover, when CD4+ T cells of HAM patients were preincubated with a monoclonal antibody to human Fas ligand (FasL), cytotoxic activity against T98G was significantly suppressed. These results suggest that damage to nervous tissues by the Fas/FasL system is involved in the pathogenesis of HAM.
We compared soluble E-selectin (sE-selectin) and L-selectin (sL- selectin) levels in sera and cerebrospinal fluid (CSF) of 30 patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM), with those of 10 patients with the relapsing-remitting form of multiple sclerosis (MS), and 16 patients with other neurological diseases (OND). Serum levels of both sE-selectin and sL-selectin, as measured by enzyme-linked immunosorbent assay, were significantly elevated in patients with HAM, compared to patients with OND. In addition, serum levels of sL-selectin were significantly elevated in HAM patients compared to MS patients. No significant difference was found in CSF levels of sL-selectin between HAM patients and controls. However, HAM patients who had received blood transfusions had significantly higher CSF levels of sL-selectin than HAM patients without a past history of transfusions, suggesting that HAM patients with past history of transfusion have a more active immunological state in the central nervous system. sE-selectin was not detected in CSF of HAM patients and controls. This finding might be based on exaggerated inflammatory conditions following increased attachment of lymphocytes to activated endothelial cells in HAM patients.
Indoor cultivation of oyster mushroom Pleurotus osteatus lead to an outbreak of extrinsic allergic alveolitis in two workers. High titer of indirect fluorescent antibody and positive precipitins against basidiospores of P. osteatus were demonstrated in sera of the patients. Mushroom workers should protect themselves from the basidiospores, being aware of their pathogenicity.
The case of a 46-year-old man with a chronic cough with sputum eosinophilia (atopic cough) caused by Trichosporon cutaneum serotype II (Trichosporon asahii) is reported. The diagnosis was made with the inhalation challenge test with T. asahii antigen. He was admitted for the diagnosis and treatment of a severe nonproductive cough in the summer season. Although his sputum contained 13% eosinophils of nucleated cells, he did not have bronchial hyperresponsiveness to methacholine or a heightened bronchomotor tone. Bronchodilator therapy was not effective for his cough. His symptoms worsened on returning home, suggesting the existence of some etiologic agent in his house. A high titer of serum anti-Trichosporon antibody was detected and antigen provocation test with the Trichosporon extract was positive: the development of a cough 6 h later and a decrease in the cough threshold to inhaled capsaicin 48 h later (7.85 microM from 31.3 microM prechallenge). This is the first report on a chronic cough with sputum eosinophilia induced by T. cutaneum (T. asahii).
A mass of 8 cm in diameter was revealed in the right upper lung field of a 46-year-old female patient. The chest X-ray film taken one year previously revealed only a linear shadow in the same position, which was thought to be a vacant cyst. The levels of carbohydrate antigen (CA) 19-9 in cyst fluid and serum were elevated, at 410,000 and 130 U/ml, respectively. After surgical resection, serum CA19-9 returned to normal. Pathologically, the cyst wall was lined with bronchial epithelium with no evidence of malignancy. Immunohistochemical study revealed CA19-9 positivity in the bronchial epithelium of the cyst wall.
We encountered three adults with varicella and bronchial mucosal lesions. Respiratory symptoms were minimal in all three. Chest X-ray films showed bilateral, diffuse, small, nodular shadows. Small, elevated lesions with white plaque's were seen on the bronchial mucosa bronchoscopically. Transbronchial lung biopsy, bronchial mucosal biopsy, and bronchoalveolar lavage were also done. The lung-biopsy specimen showed infiltration of lymphocytes into the interstitial space: VZV antigen was found by immunohistochemical staining of the lesion in one case. Analysis of bronchoalveolar lavage fluid revealed abnormally low CD 4/8 ratios in three cases. These findings suggest a high incidence of respiratory complications, especially bronchial lesions, despite the lack of respiratory symptoms, in adults with varicella.
Fifteen patients with human T-cell lymphotropic virus type-I (HTLV-I)-associated myelopathy (HAM) were treated in an uncontrolled preliminary trial by oral administration of pentoxifylline (PTX). Motor function, neurological evaluation, immunological markers and parameters were evaluated after four weeks. In 13 of the 15 patients, motor disability, especially spasticity, improved substantially. PTX suppressed spontaneous proliferation of peripheral blood mononuclear cells in 14 of the 15 patients at four weeks. No adverse effect was observed. We concluded that PTX may be a safe and beneficial agent for the treatment of HAM.
To clarify if pentoxifylline (PTX) may have therapeutic potential for human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM), we investigated the in vitro effect of PTX on spontaneous proliferation of peripheral blood lymphocytes (SPP), as well as on the expression of adhesion molecules, such as lymphocyte function antigen-1 (LFA-1) and very late activation antigen-4 (VLA-4), and the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and granulocyte-monocyte colony stimulating factor (GM-CSF), in cultured PBMC from 10 HAM patients, compared with control subjects. SPP in HAM patients was significantly suppressed in a dose-dependent manner with PTX. Using flow cytometry, PTX was found to down-regulate the expression of LFA-1 and VLA-4 on CD4+ and CD8+ T cells in HAM patients as well as control subjects. However, the fall in the expression of LFA-1 and VLA-4 on CD4+ T cell population in HAM patients was higher than that of control subjects. PTX caused a significant suppression of spontaneous production of TNF-alpha by cultured PBMC of HAM patients. It also caused a small but significant suppression GM-CSF and IFN-gamma production. Collectively, our results suggest that PTX might be therapeutically effective at critical points in the immunopathogenesis of HAM.