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Biomedical subjects

Y Ushio

Publications and source records attributed to Y Ushio.

At least 163 records · Page 9Linked to original sources
PubMed1996

Intramedullary epidermoid cyst in the brain stem: case report.

BACKGROUND: The incidence of intracranial epidermoid cysts is between 0.2% to 1.8% of all brain tumors. They usually occur in the cerebellopontine angle or parasellar region. Intramedullary epidermoid cyst is rare and only nine cases have been previously reported. METHODS: A 69-year-old woman had progressive left hemiparesis for 2 years. Computed tomography scanning and magnetic resonance imaging (MRI) revealed that there was a cystic tumor in the pons that was compressing the brain stem. A part of the tumor cyst wall and the content of the cyst were surgically removed by right subtemporal transtentorial approach. The histologic diagnosis was epidermoid cyst. After the surgery, the left hemiparesis was improved and there was no sign of the tumor growth by MRI. CONCLUSION: The outcome of the previous cases with radical tumor resection was poor compared with the present case in which only a part of the cyst wall and the content were removed. Therefore, radical removal of the whole tumor may not be necessary for intramedullary epidermoid cyst of the brain stem.

Aged↗
PubMed1996

Gabaergic transmission and tyrosine hydroxylase expression in the nigral dopaminergic neurons: an in vivo study using a reversible ischemia model of rats.

The authors conducted an in vivo study, using a rat striatal ischemic model, of the effect of GABAergic transmission upon the dopamine synthesizing enzyme tyrosine hydroxylase in the neurons of the substantia nigra pars compacta. Two hours transient middle cerebral artery occlusion produced massive striatal ischemic damage resulting in a marked decrease of GABAergic projection to the ipsilateral substantia nigra. Histological examinations were conducted in rats killed at three, seven, 15, 30 and 94 days after ischemia. The immunoreactivity for tyrosine hydroxylase in the ipsilateral pars compacta was unaltered up to three days after the ischemic insult, but it was markedly decreased at seven days post-ischemia. At this stage, the number of neurons positive for tyrosine hydroxylase was significantly decreased in the ipsilateral pars compacta, whereas there was no significant reduction in the number of pars compacta neurons containing Nissl substance. By 30 days post-ischemia, the tyrosine hydroxylase-positive cell number in the ipsilateral pars compacta appeared to be equivalent to that of the contralateral side. It was also noted that continuous intraventricular administration of a GABAA receptor agonist muscimol, initiated from 24 h post-ischemia, effectively prevented the transient reduction of immunoreactivity for tyrosine hydroxylase in the ipsilateral pars compacta at seven and 15 days after ischemic insult. The present study revealed that the striatal ischemic lesion induced a transient down-regulation of tyrosine hydroxylase synthesis in the pars compacta neurons, which could be prevented by administration of GABA agonist, suggesting that GABAergic transmission greatly affects dopamine metabolism in these cells.

Animals↗
PubMed1996

Cyclic AMP inhibits activation of mitogen-activated protein kinase and cell proliferation in response to growth factors in cultured rat cortical astrocytes.

The cyclic AMP (cAMP)-induced inhibitory effect on cell proliferation was examined through inhibition of mitogen-activated protein kinase (MAP kinase) activation in cultured rat cortical astrocytes. Basic fibroblast growth factor (bFGF) at 10 ng/ml maximally stimulated MAP kinase activity, which peaks during 10 min and prolonged for 24 h. Likewise, DNA synthesis was maximally potentiated with 10 ng/ml bFGF and correlated with MAP kinase activity in a dose-dependent manner. Dibutyryl cAMP (dbcAMP) at 1 mM and isoproterenol at 10 microM inhibited MAP kinase activation and DNA synthesis potentiation with bFGF and platelet-derived growth factor to the control level in cultured astrocytes and C6 glioma cells. The stimulation with bFGF caused a prominent translocation of MAP kinase from the cytosol to the nucleus after 1 h in astrocytes. Treatment of the cells with dbcAMP and isoproterenol completely prevented the translocation of MAP kinase. In experiments with 32P-labeled cultured astrocytes, phosphorylation of Raf-1 was apparently stimulated with bFGF. Treatment with dbcAMP or isoproterenol had a greatly inhibitory effect on the stimulation of Raf-1 phosphorylation with bFGF. Consistent with the effect on Raf-1 phosphorylation, dbcAMP and isoproterenol completely prevented bFGF-induced phosphorylation of MAP kinase kinases, target proteins of Raf-1. Our observations suggest that cAMP-induced suppression of cell growth in astrocytes is due to the inhibitory effect on activation of MAP kinase and its translocation to the nucleus and that the site of the cAMP action is located at Raf-1 or the upstream site of Raf-1.

Adrenergic beta-Agonists↗
PubMed1996

Expression and alternative splicing of Pit-1 messenger ribonucleic acid in pituitary adenomas.

Twenty-eight human pituitary adenomas were analyzed for the expression of Pit-1 messenger ribonucleic acid (mRNA) by using reverse transcriptase-polymerase chain reaction analysis of frozen-section mRNA. Pit-1 mRNA was detected in all functioning tumors and in 9 of 11 nonfunctioning tumors. Pit-1 beta, which is a more active isoform of transcriptional factor for growth hormone than Pit- alpha and which arises from an alternative splicing mechanism, was detected in 14 of 17 functioning tumors and in 5 of 11 nonfunctioning tumors. The transcript that corresponds to Pit-1T, which increases thyroid-stimulating hormone beta promoter activity in rat thyrotropic tumor cells, was not found. There was no significant difference in the total Pit-1 (alpha+beta) mRNA expression level between functioning tumors and nonfunctioning tumors. Growth hormone-producing tumors and other pituitary adenomas also showed no significant difference in the Pit-1 beta/Pit-1 alpha expression ratio. Our data suggest that the major role of Pit-1 gene in pituitary adenoma might not be involved in the regulation of hormone production.

Adenoma↗
PubMed1996

Multiple cerebral arterial occlusions in a young patient with Sjögren's syndrome: case report.

We describe a case of a young patient with multiple occlusions of major cerebral arteries and Sjögren's syndrome. This 17-year-old female patient experienced repeated transient ischemic attacks of right hemiparesis, speech disturbance, and unconsciousness. Angiography revealed progressive occlusion of the bilateral carotid and vertebral arteries. Examinations, including a serological test, a rose bengal test, Ga scintigraphy, and a biopsy of the parotid gland, indicated Sjögren's syndrome. The patient was successfully managed with bypass surgery. Patients with Sjögren's syndrome may experience progressive occlusion of the major cerebral arteries resembling that of moyamoya disease.

Adolescent↗
PubMed1996

Failure to reject an allografted tumor after elimination of macrophages in mice.

After an i.p. transplantation of an allogeneic tumor (Meth A) to C57BL/6 mice, a macrophage (M phi)-rich, non-T, non-NK cell population is induced as the major infiltrate and cytotoxic cells. We here evaluated the role of the M phi s in the rejection of allografted Meth A cells and characterized the M phi s in comparison with other well-known M phi s. At all time intervals after transplantation, the highest cytotoxic activities against Meth A tumor were obtained with the M phi-rich population. In addition, the lymphocyte-rich population had a significant but low cytotoxic activity, whereas two other population types, granulocytes and large granular cells, were inactive. When the M phi-rich or the T cell-depleted M phi-rich population was i.p. transplanted simultaneously with Meth A cells into untreated C57BL/6 mice, the tumor cells were rejected without growth. After specific elimination of M phi s by in vivo application of dichloromethylene diphosphonate-containing liposomes, the cytotoxic activity against Meth A cells was hardly induced at the transplantation site of Meth A cells and the allografted Meth A tumor continued to grow, indicating that a type of M phi is the effector cell essential for the rejection. In contrast to other well-known M phi s, the cytotoxic activity against Meth A cells was cell-to-cell contact dependent and soluble factor (e.g., NO and TNF-alpha) independent. Moreover, the cytotoxic activity of the M phi s (H-2b) against 51Cr-labeled Meth A (H-2d) cells was inhibited by the addition of unlabeled H-2d, but not H-2b, H-2k or H-2h, lymphoblasts as well as Meth A cells, implying the specific interaction of the M phi s with H-2d cells.

Animals↗
PubMed1996

Epidemiological study of primary intracranial tumors in childhood. A population-based survey in Kumamoto Prefecture, Japan.

Between 1989 and 1995, we diagnosed primary intracranial neoplasms in 79 children younger than 15 years. All of them belonged to a well-defined population residing in Kumamoto Prefecture, Japan. Of the tumors, 64 (81.0%) were confirmed microscopically. The age-adjusted annual incidence rate was 34.3 cases per million child population. There was a marked difference in the incidence rate between boys (47.1) and girls (22.05). The age-specific annual incidence per million was 24.3 cases for the 0- to 4-year age group, 46.7 for the 4- to 9-year age group and 30.8 for the 10- to 14-year age group. The highest incidence rate was seen in 5- to 14-year-old boys (53.5), the lowest in 10- to 14-year-old girls (7.1). The most common tumors were astrocytomas (41.8%), with an incidence of 14.52 per million, followed by germ cell tumors (15.1%), with an incidence of 6.24 per million, craniopharyngiomas (15.1%), incidence 5.25 per million, ependymomas (6.3%), incidence 2.19 per million, and medulloblastomas (6.2%), incidence 2.19 per million. The distribution of tumor types varied with patient age at the time of diagnosis. Although no germ cell tumors were encountered in the 0- to 4-year age group, in the 10- to 14-year age group, they comprised about one third of all tumors. In contrast, white craniopharyngiomas were rare in the 10- to 14-year age group, they made up more than 22% in the 0- to 4-year age group. In this survey of Japanese children, we found a higher incidence of primary intracranial tumors, especially germ cell tumors and craniopharyngiomas, and a lower incidence of medulloblastomas compared to the incidence reported for Western countries.

Adolescent↗
PubMed1996

Subregional loss of putaminal efferents to the basal ganglia output nuclei may cause parkinsonism in striatonigral degeneration.

In this study, we examined the topographic involvement of the putaminal projection neurons and their axons in the globus pallidus and substantia nigra, which we visualized by calcineurin immunostaining, in the basal ganglia of patients with striatonigral degeneration (SND). In all cases examined, there was a marked decrease in number of calcineurin-immunopositive neurons in the caudal and lateral portion of the putamen. Also, marked depletion of calcineurin-immunoreactive putaminal efferents was consistently present in the posteroventrolateral portions of the globus pallidus interna (GPi) and externa, and in the ventrolateral portion of the substantia nigra pars reticulata (SNr) topographically corresponding to the putaminal lesion. In view of the functional model of the basal ganglia "motor" circuit, these findings suggest that subregional deafferentation of the GPi/SNr (i.e., basal ganglia output nuclei) from putaminal inputs may be responsible for parkinsonism in patients with SND.

Aged↗
PubMed1996

Transient alpha coma following minor head trauma in a patient with primitive trigeminal artery.

A 26-year-old male presented with transient alpha coma following minor head trauma after a traffic accident. His consciousness disturbance suddenly recovered 3.5 hours later. He had not suffered cardiac arrest before admission, nor was taking any drugs. Magnetic resonance (MR) angiography 6.5 hours after consciousness recovery disclosed persistent primitive trigeminal artery (PTA) with minor segmental narrowings. Three months later, MR angiography revealed that both the PTA and the distal basilar artery were slightly diated without evidence of narrowing. Conventional angiography and single photon emission computed tomography revealed that the distal basilar artery was supplied mainly by the PTA. Transient circulatory disturbance due to traumatic angiospasm of the PTA may have caused hypoperfusion of the upper brainstem in this patient.

Adult↗
PubMed1996

Epidemiological study of primary intracranial tumors: a regional survey in Kumamoto Prefecture in the southern part of Japan.

This survey consists of 1117 residents of Kumamoto Prefecture who were diagnosed with primary intracranial tumors between 1989 and 1994. Age, sex, tumor type, and date of diagnosis were recorded in all cases; 79% of the diagnoses were confirmed histologically. The overall age-adjusted incidence rate was 9.47 per 100,000 population per year. Among males, the age-adjusted incidence rate was 8.24 per 100,000 per year, and the breakdown included 2.36 gliomas, 1.56 meningiomas, 1.46 pituitary tumors, and 0.99 neurinomas. Among females, the comparable overall rate was 10.7; that included a rate of 3.95 for meningiomas, 2.04 for gliomas, 2.16 for pituitary tumors, and 0.75 for neurinomas. Meningiomas were the most common tumor, with an average annual age-adjusted incidence of 2.76 per 100,000 population. The highest incidence of meniningiomas was 13.02 per 100,000 among women aged 70 to 79 years. The highest incidence of gliomas (5.71 per 100,000 males and 5.29 per 100,000 females) was seen in patients between 60 and 69 years of age. Meningiomas, pituitary adenomas, and malignant lymphomas occurred at a higher rate in females (male/female ratio: 0.39, 0.68, and 0.81, respectively). On the other hand, gliomas, neurinomas, and germ-cell tumors occurred more often in males (male/female ratio: 1.16, 1.32, and 4.29, respectively). Meningiomas and germ-cell tumors tended to exhibit gender specificity.

Adolescent↗
PubMed1996

Reconstruction of the posterior inferior cerebellar artery in the treatment of giant aneurysms. Report of two cases.

Two techniques of revascularizing the posterior inferior cerebellar artery (PICA) during aneurysm surgery are presented. One involves transposition of the PICA to the vertebral artery proximal to the aneurysm using a superior temporal artery (STA) as a graft. This is used in cases in which the PICA has branched off from the wall of the giant vertebral artery aneurysm. The other technique involves end-to-end anastomosis of the PICA after excision of a giant distal PICA aneurysm located at the cranial loop near the roof of the fourth ventricle. The reconstructions of the PICA described here are surgical procedures designed to preserve normal blood flow in the PICA in patients treated for giant aneurysms involving that artery.

Aged↗
PubMed1996

[Prognostic factors in malignant gliomas].

The most important prognostic factor in malignant gliomas is histopathological diagnosis of the tumor. The survival of patients with anaplastic astrocytoma is much longer than that of patients with glioblastoma. The median survival of the former has been improved up to almost 4 years by the recent progress of multidisciplinary treatment, whereas that of the latter has still remained in less than 1.5 years. Other important factors proved to be associated with survival of patients with malignant gliomas are the age of patients, Karnofsky performance status on admission, surgery, radiotherapy and chemotherapy. There is substantial evidence suggesting an association between younger patient age and longer survival in adults with supratentorial anaplastic astrocytoma as well as glioblastoma. It is also consistent with evidence that the patients with better performance status on admission live longer after treatment. Gross total resection of supratentorial anaplastic astrocytoma is directly associated with longer and better survival when compared to subtotal or partial resection. For glioblastoma, however, gross total resection has not been proved to have a significant survival advantage over subtotal or partial removal. Radiotherapy has been proved to be associated with longer survival of patients with supratentorial anaplastic astrocytoma and glioblastoma. Chemotherapy has not proved effective in prolonging the survival of patients with glioblastoma. Multidrug chemotherapy with CCNU, procarbazine and vincristine has proved to have significant survival advantage over BCNU alone, suggesting chemotherapy is also a prognostic factor in patients with anaplastic astrocytoma.

Adolescent↗
PubMed1996

Expression of tissue factor in glioma.

Tissue factor (TF) is a cell surface glycoprotein that initiates the extrinsic coagulation protease cascade and it is expressed in some tumor cells. TF belongs to the interferon receptor family, and it is one of the early immediate genes, suggesting that TF has a biological function other than hemostasis. We investigated the expression of TF in gliomas. Immunocytochemistry showed the expression of TF in 3 glioma cell lines. Immunohistochemical analysis of 44 surgical specimens revealed that all gliomas were positive for TF, and 19 (95%) of 20 glioblastomas, 12 (86%) of 14 anaplastic astrocytomas and 1 (10%) of 10 benign gliomas were moderately or strongly positive for TF. Our study showed that TF is expressed in gliomas, and that the level of TF expression is correlated with the grade of malignancy of the glioma, suggesting that TF may participate in cell growth.

Brain Neoplasms↗
PubMed1995

Mosaic organization of calcineurin immunoreactivity in the adult cat striatum.

Calcineurin is a Ca2+/calmodulin-regulated protein phosphatase which is thought to play an essential role in the intracellular Ca(2+)-signal transduction. The present study showed that calcineurin immunolabeling was differentially concentrated in the two distinct compartments showing a mosaic-like pattern in the adult cat striatum. The compartment of heightened calcineurin immunolabeling corresponded to the extrastriosomal matrix visualized by calbindin-D28K immunostaining. Under the light microscope, striatal neurons appeared to be less strongly immunoreactive for calcineurin in the striosomes than in the matrix compartment. These findings suggest that the novel striatal compartments may differ in the intracellular Ca(2+)-signaling cascade associated with protein dephosphorylation.

Animals↗
PubMed1995

Survival of neurons containing the enzyme nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase in static slice cultures of adult rat striatum.

The present study concerns the survival potential of mature neurons containing the enzyme nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase in the static slice culture of adult rat striatum. In the striatal tissues immediately after slicing, there was a scattered distribution of NADPH-diaphorase neurons stained in a Golgi-like manner, and the cell density of those neurons was 53 +/- 5 (mean +/- SEM; n = 10) cells per mm2. The time-sequential cell density analysis disclosed that the number of striatal NADPH-diaphorase neurons surviving after 1, 2, 4 and 6 day in culture were 26 +/- 5, 8 +/- 2, 5 +/- 2, and 3 +/- 2 (means +/- SEM; n = 10) cells per mm2, respectively. Thus, approximately 50% of striatal NADPH-diaphorase neurons survived for 1 day and a significant proportion of these neurons, although their number gradually decreased, were maintained in culture for at least several days. The conspicuous survival of the striatal NADPH-diaphorase neurons in slice culture is thought to reflect the damage-resistant natures of these cells.

Animals↗
PubMed1995

Change of phosphotyrosine immunoreactivity on microglia in the rat substantia nigra following striatal ischemic injury.

Using immunohistochemistry, we investigated changes in phosphotyrosine (P-Tyr) immunoreactivity on the microglia of the rat substantia nigra (SN) following striatal ischemic injury produced by transient middle cerebral artery (MCA) occlusion. Anterograde axonal degeneration in the SN due to striatal ischemic injury was detected by depletion of calcineurin immunoreactivity in that region from 1 day after operation. From 3 days to 1 month (the longest period examined in this study) after MCA occlusion, there was a significant increase in P-Tyr immunoreactivity in the SN ipsilateral to the MCA occlusion. Also, light microscopic observation showed that the microglia exhibited an increased immunoreactivity for P-Tyr and characteristic morphological changes in the ipsilateral SN. The present results indicate that a signal transducing cascade(s) associated with tyrosine phosphorylation may be involved in the activation of the microglia in the SN responding to anterograde degeneration of the striatonigral pathway.

Animals↗
PubMed1995

Striatal cells containing the Ca(2+)-binding protein calretinin (protein 10) in ischemia-induced neuronal injury.

The present study concerns the vulnerability of striatal interneurons immunopositive for the Ca(2+)-binding protein calretinin to ischemic neuronal injury. An immunohistochemical study was carried out on the striata of rats which had undergone transient middle cerebral artery occlusion. Two weeks after the ischemia, there was a marked reduction in the number of calretinin-positive neurons in the ipsilateral ischemic lesion, although the striatal interneurons positive for parvalbumin, which are a neuronal population distinct from the calretinin-immunoreactive cells in the striatum, were spared in the insulted areas. The present data indicate that the striatal calretinin-positive neurons are less resistant to transient ischemia, suggesting that there may exist vulnerability differences among the striatal interneurons in ischemia-induced neuronal injury.

Animals↗