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Biomedical subjects

A Hayashi

Publications and source records attributed to A Hayashi.

At least 181 records · Page 10Linked to original sources
PubMed1997

Rolipram, a phosphodiesterase-4-selective inhibitor, promotes the survival of cultured rat dopaminergic neurons.

We evaluated the effects of rolipram, a selective inhibitor of phosphodiesterase (PDE) 4, on the survival of dopaminergic neurons in 13-day culture. Rolipram did not affect the survival of dopaminergic neurons in the absence of forskolin, but significantly enhanced the survival of dopaminergic neurons in the presence of 10(-5) M forskolin in a concentration-dependent manner (10(-8) - 10(-5) M). Rolipram also enhanced the neurotrophic effect of forskolin on total neurons including dopaminergic and non-dopaminergic neurons at a high concentration (10(-5) M), but did not affect the survival of cells containing glutamate or gamma-aminobutylic acid. A non-selective PDE inhibitor, 1-isobutyl-3-methylxanthine, caused a marked increase of dopaminergic neurons, whereas selective inhibitors of PDE2 and PDE3 showed far weaker effects. A PDE1 inhibitor, on the other hand, caused non-specific cell death in the presence or absence of forskolin. These findings suggest that rolipram has a potential to enhance the survival of dopaminergic neurons selectively by way of PDE4 inhibition.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1997

Thymolipoma: clinical and pathological features--report of three cases and review of literature.

We report three recently resected cases of thymolipoma. Two cases (case 2 and 3) were female and the other (case 1) was male. The age of these three were 41 years, 63 years, and 29 years, respectively. While two cases (case 1 and 2) were asymptomatic, the other (case 3) had associated myasthenia gravis. Preoperative examination in each case was performed using chest CT scan or chest MRI, or both. Only one case (case 1) was diagnosed as thymolipoma preoperatively, and this was by a chest MRI showing the mass in continuity with the thymus. The diagnosis of each lesion was confirmed histologically by their composition of lobules of mature adipose tissue with minute islands of thymic tissue consisting of epithelial cells, lymphocytes, and Hassall's bodies.

Adult↗
PubMed1997

Development of cancer vaccine by tumor rejection antigens.

Identification of the MAGE genes allowed us the molecular approach to identify genes encoding tumor rejection antigens expressed on human cancer cells. MAGE-1 proteins are normal tissue antigens compartmentalized in the particular testicular cells playing an important role in the early phase of the spermatogenesis. The MAGE-1, -2, -3, -4 and -6 genes are preferentially expressed in many different cancers at both the mRNA and protein levels. The MAGE genes, particularly MAGE-1, became positive in relatively advanced stages of cancers and recurrent cancers. Approximately one-third to half of human cancers except for myelo-monocytic leukemia expressed at least one of these MAGE genes. The MAGE gene products shall be appropriate target molecules for development of new cancer vaccine.

Animals↗
PubMed1997

Thymolipoma associated with myasthenia gravis.

In a 29-year-old woman with myasthenia gravis and no visible mediastinal mass, the resected thymus was found to contain a small thymolipoma. Relief of the neuromuscular symptoms followed thymectomy. A very small thymolipoma may be associated with myasthenia gravis even if the content of though thymic tissue is low.

Adult↗
PubMed1997

Activation of protein tyrosine phosphorylation after retinal branch vein occlusion in cats.

PURPOSE: The authors examine the effect of retinal branch vein occlusion (BVO), a common retinal vascular disorder, on protein tyrosine phosphorylation, production of angiogenic growth factors, and activation of signal proteins in the tyrosine kinase pathways in the retina. METHODS: Retinal branch vein occlusion was induced in cat retina by coagulation of retinal veins with diathermy. At 2 days, 1, 3, and 6 weeks after induction of BVO, the retina was divided into three parts: a part within the distribution of the occluded vein (BVO[IN]) or a part outside the distribution of the occluded vein (BVO[OUT]). Each part of the retina was prepared for Western blot analysis of tyrosine-phosphorylated proteins, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and four signal proteins in the tyrosine kinase pathways, which were phospholipase C gamma (PLC gamma), C-Src, SH2-containing protein (SHC), and mitogen-activated protein kinase (MAPK). RESULTS: Overall, tyrosine-phosphorylated proteins were increased after BVO, especially in BVO(IN) at 2 days and 1 week. The VEGF and bFGF also were increased in BVO(IN) at 1 week and 2 days, respectively. The PLC gamma and MAPK were activated at these time points. The C-Src and SHC were not activated in the retina after BVO. CONCLUSIONS: The BVO increased overall protein tyrosine phosphorylation in the cat retina in association with increase of angiogenic growth factors (VEGF and bFGF) and activation of two signal proteins (PLC gamma and MAPK) in the tyrosine kinase pathways. These results suggest that the protein tyrosine phosphorylation may in part play an important role in mitogenesis of vascular endothelial cells and other retinal responses after BVO.

Animals↗
PubMed1997

[Chronic expanding hematoma following pneumonectomy managed with a thoracic balloon: a case report].

A 64-year-old male was treated for a chronic expanding hematoma three years after pneumonectomy for left lung cancer (p T2N2M0, Stage IIIA). Two years prior to admission a left pleural effusion shadow was detected on a follow-up chest X ray, and since then there had been a progressive mediastinum shift to the right. The suspected diagnosis on referral was recurrent lung cancer or giant intrathoracic hematoma. Chest CT scans and thoracentesis led to a diagnosis of a chronic expanding hematoma developing after pneumonectomy. Surgery was performed because of the severity of symptoms and the progressive nature of the tumor. Histopathological examination confirmed the diagnosis of chronic expanding hematoma. During the operation, it was difficult to achieve hemostasis, but bleeding was effectively managed with a thoracic balloon.

Catheterization↗
PubMed1997

Genistein, a protein tyrosine kinase inhibitor, ameliorates retinal degeneration after ischemia-reperfusion injury in rat.

PURPOSE: The authors sought to determine the effect of genistein, a naturally occurring protein tyrosine kinase inhibitor, in a model of ischemia-reperfusion injury in the rat retina. METHODS: Ischemia-reperfusion injury was induced by temporary optic nerve ligation. A dose of 0.034 mg, 0.34 mg, and 3.4 mg of genistein or dimethyl sulfoxide (DMSO) alone was injected intraperitoneally 1 hour before the ligation of the optic nerve and just after the start of reperfusion. After 48 hours of reperfusion, the effect of genistein on overall protein tyrosine phosphorylation in the retina was studied using Western blot analysis. After 168 hours, the effect of increasing doses of genistein on retinal degeneration was examined by quantitative morphometric analysis of histologic sections of the retina. RESULTS: The authors found that tyrosine phosphorylation was increased after 48 hours of reperfusion in the ischemia-reperfusion-injured eyes treated with DMSO alone. A severe inner retinal degeneration was observed in the animals treated with DMSO alone after 168 hours of reperfusion. The treatment with 3.4 mg genistein inhibited the increase in tyrosine phosphorylation and protected the eyes significantly from the induced ischemic retinal degeneration by morphometric analysis of the mean thickness of the inner limiting membrane to the outer limiting membrane, the inner plexiform layer, and the inner nuclear layer (P < 0.02). Treatments with lower amounts of genistein (0.034 mg and 0.34 mg) did not show a significant protection of retinal degeneration after the injury. CONCLUSIONS: Systemic administration of high dose of genistein, a dietary-derived isoflavone, can ameliorate an ischemia-reperfusion-induced retinal degeneration. Genistein may be useful to prevent neuronal degeneration in the inner retina as a result of ischemic injury.

Animals↗
PubMed1997

[A case of frontal gait apraxia caused by hypoxic encephalopathy].

We reported a rare case who had hypoxic-encephalopathy causing frontal apraxia of gait. The patient, a 34-year-old female, was admitted in July, 1994, complaining of difficulty in walking after anoxic brain damage caused by ventricular arrhythmia. She had difficulty in raising her feet, which appeared to be rooted to the floor. There was no evidence of motor paralysis, spasticity, rigidity or sensory loss, but she did show frontal lobe signs such as foot grasp reflex and Gegenhalten. Cranial MRI showed slight atrophy of the frontal lobe. On T2 weighted image, high-intensity areas were detected at the posterior internal capsule and corona radiata. Single photon emission CT (123I-IMP) demonstrated a low perfusion area which included the inferomedical part of the frontal lobe. After 8 months of hospitalization, her postural instability and unsteady gait slowly improved without treatment as frontal signs such as foot grasp reflex disappeared. We speculate that her apraxia of gait may result from grasp reflex and Gegenhalten.

Adult↗
PubMed1997

[Role of endothelin-B receptors in the pulmonary circulation].

Endothelin-1 (ET-1) is a potent vasoactive peptide and is thought to play an important role in the regulation of vascular tone. ET-1 can both constrict blood vessels, via endothelin-A (ET-A) receptors in vascular smooth muscle cells, and dilate then via endothelin-B (ET-B) receptors in endothelial cells in the systemic circulation. To determine the role of ET-B receptors in the pulmonary circulation, we examined the hemodynamic effects of a selective ET-B receptor agonist (IRL 1620) in rats. In rat lungs perfused with a salt solution, IRL 1620 caused pulmonary vasoconstriction in a dose-dependent manner. In lungs perfused with a hypoxic half-blood solution (10% O2), doses of IRL 1620 less than 10 nM caused pulmonary vasodilation, but higher doses caused pulmonary vasoconstriction. IRL 1620 caused transient vasodilation of the systemic circulation at every dose used (0.1, 1, and 5 nmol/kg) in anesthetized rats. In contrast, the effects of IRL 1620 on the pulmonary circulation varied with the dose. Small doses (0.1 or 1 nmol/kg) caused pulmonary vasodilation, but a higher dose (5 nmol/kg) caused pulmonary vasoconstriction. These results show tachyphylaxis in the pulmonary vasodilator response to IRL 1620, but not in the systemic vasodilator response. The present data show the dual action (vasoconstriction and vasodilation) of ET-B receptors.

Animals↗
PubMed1997

[A case of post-poliomyelitis muscular atrophy with cranial nerve signs and widespread muscular atrophy of the extremities].

Here we report a case of a 56-year-old male with post-poliomyelitis muscular atrophy (PPMA), who presented with cranial nerve signs and widespread atrophy of the extremities. He had suffered from poliomyelitis at the age of 2 years. After recovery from the acute stage, the paralysis remained in his left arm. He noticed muscle weakness of the right upper and lower extremities at the age of 45 years and the muscle atrophy progressed to his arms, hip and thigh at the age of 55 years. Neurological examination revealed muscle atrophy of the neck and disturbance of left V, VIII, IX, X and bilateral XI cranial nerves. We diagnosed this case as PPMA from his history and electromyographic and muscle biopsy findings which suggested chronic denervation. Among the 21 PPMA cases in the past in which the acute poliomyelitis had resulted in paralysis of the only one limb, ours was the only case that had muscle atrophy of all the limbs. Cranial nerve involvement is known to occur in acute poliomyelitis; therefore, there is a possibility that the involvement of the cranial nerves in our case might be a delayed progressive symptoms.

Cranial Nerves↗
PubMed1996

Serum of Isaacs' syndrome suppresses potassium channels in PC-12 cell lines.

Blockage of K+ channels in nerve terminals by immunoglobulin is the speculated pathomechanism of Isaacs' syndrome. Using patch-clamp technique (whole-cell clamp), we investigated the effects on K+ current of serum taken from 2 patients with Isaacs' syndrome employing the clonal cell line PC-12. The addition of a patient's serum to the perfusion solution had little effect on the K+ current of P-12 cells. In contrast, K+ current was reduced by 25-80% when cells were cultured for 3-6 days with 2% serum as compared to control serum values. Suppression of the K+ current appears to develop gradually over the period of culture. Our results suggest that the pathomechanism of Isaacs' syndrome is caused by K+ channel suppression via a humoral factor(s) in the serum, which subsequently induces nerve hyperexcitability.

Adult↗
PubMed1996

Preferential activation of CD4+V beta 5.2/5.3+ intestinal intraepithelial lymphocytes in the inflamed lesions of Crohn's disease.

To analyze the nature of intestinal intraepithelial lymphocytes (iIELs) in inflammatory intestinal disease, we established T cell lines of iIELs isolated from endoscopic biopsied ileal and colonic mucosa of Crohn's disease patients. Seven T cell lines from the inflamed terminal ileum of 13 patients, but none of 16 T cell lines from normal terminal ileum, have shown a deviation of T cell receptor variable region gene usage and were enriched in the proportion of CD4+V beta 5.2/5.3+ cells. CD4+V beta 5.2/5.3+ cells in the T cell lines were not increased after stimulation with purified protein derivatives or 65-kDa heat-shock protein but significantly increased after stimulation with staphylococcal enterotoxins C1 and D. Those cells showed increased cytolytic activity against target cells cross-linked by anti-V beta 5.2/5.3 and produced a large amount of interferon-gamma. These results indicated that CD4+V beta 5.2/5.3+ iIELs were preferentially activated in the inflamed lesions of Crohn's disease and may play a possible role in the triggering and progression of human inflammatory intestinal disease.

Adolescent↗
PubMed1996

Evaluation of a new solution containing trehalose for twenty-hour canine lung preservation.

We examined the efficacy of two new preservation solutions containing trehalose--an extracellular type (ET-K) of solution and an intracellular type (IT-K) of solution--in relation to that of Euro-Collins (EC) solution in 20-h canine lung preservation. Canine lungs were flushed with one of the three solutions (n = 5 for each solution) after pretreatment with PGE1 (20 micrograms/kg) and were stored for 20 h at 4 degrees C. The left lungs were transplanted and evaluated to 6 h post transplant. In the ET-K group, the arterial oxygen tension after reperfusion was significantly higher than in the IT-K and EC groups. The pulmonary vascular resistance, wet/dry weight ratio, and histological evaluation of each transplanted lung in the ET-K group were also better than in the IT-K and EC groups. This indicates that ET-K solution is useful for 20-h preservation of canine lung grafts.

Analysis of Variance↗
PubMed1996

Ascorbic acid reduces tropoelastin levels in culture medium of chick skin fibroblasts.

Ascorbic acid reduced tropoelastin levels in the culture medium of embryonic chick skin fibroblasts to one-third or one-fourth of their original value in a dose- and exposure time-dependent manner under conditions in which collagen synthesis was stimulated 1.8-fold. The steady-state level of elastin mRNA remained essentially constant, whereas the collagen mRNA content increased in proportion to the increase in collagen synthesis with ascorbic acid treatment. These results suggest that the reduction of tropoelastin levels is not controlled by the elastin mRNA level but, rather, is related to the posttranslational modification of the tropoelastin molecule.

Actins↗
PubMed1996

Melanogenesis, biosynthetic phenotype of fibronectin and collagen, and migrating activity in cloned B16 mouse melanoma cells.

Three clones, melanotic (M3), amelanotic (A4 and A7) cells were isolated from B16 F10 mouse melanoma cell line. These clones exhibited different biosynthetic activities of fibronectin and collagen: A4 clone showed relatively active synthesis of both collagen and fibronectin, and A7 clone exhibited most active fibronectin synthesis, whereas no significant synthesis of these molecules was observed in M3 clone. No significant difference in growth rate was observed in these three clones. Migrating activities measured by basement membrane matrix-coated dishes were greater in A7 clone than in A4 and M3 clones. Messenger RNA levels of collagen and fibronectin paralleled collagen and fibronectin synthesis in these clones whereas tyrosinase mRNA level was unaltered between melanotic (M3) and amelanotic (A4 and A7) cells. These results indicate that B16 melanoma cells have heterogeneous cell populations consisting of different biosynthetic and metastatic properties. These clones may provide good tools for studying the relationship between the phenotypes of melanogenesis biosynthesis of extracellular macromolecules and migrating activity of melanoma cells.

Animals↗
PubMed1996

Expandable metallic stents for tracheobronchial stenoses in esophageal cancer.

BACKGROUND: Tracheobronchial stenosis in patients with esophageal cancer can be life threatening. Few reports have discussed use of expandable metallic stents for central airway stenoses in patients with esophageal cancer. METHODS: Twelve patients with esophageal cancer underwent placement of expandable metallic stents for respiratory distress caused by tracheobronchial stricture. Single or double metallic stents were placed in the stenotic airways under fluoroscopic guidance. Improvement in respiratory symptoms and clinical outcome were assessed. RESULTS: Most stenoses were located in the trachea or the left main bronchus. From one to four expandable metallic stents were placed in each stricture site, with immediate relief of respiratory symptoms in 8 patients. One patient with tracheomalacia in alive 3 years after stent placement and another is alive 6 months after stent insertion. The other 10 patients lived from 10 to 70 days (mean; survival, 35 days) after stent placement. Death was due to progression of disease. CONCLUSIONS: Although metallic stents are useful for relieving respiratory distress in patients with advanced esophageal cancer, additional therapies should be considered.

Aged↗