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Biomedical subjects

T Tsubokawa

Publications and source records attributed to T Tsubokawa.

At least 91 records · Page 5Linked to original sources
PubMed1991

Serotonergic effects on carbonic anhydrase activity in the choroid plexus.

The carbonic anhydrase (CA) activities in the choroid plexus of dogs were investigated by electron microscopy, and the effects of 5-hydroxytryptophan (5-HTP) on them were examined to elucidate the participation of serotonin in the production of cerebrospinal fluid. The reaction products yielded by the method employed proved to be CA activity by elimination tests using acetazolamide (Diamox). Following administration of 5-HTP, the CA activities fell to 43.3% of the control value, that is, approximately 56% of the CA activities in the choroid plexus were affected by serotonin. When tetrabenazine (TBZ) was administered, the CA activities in the choroid plexus decreased to 22.4% of the control value. These results suggest that the CA activity in the choroid plexus is remarkably suppressed when nervous control of the choroid plexus is disturbed by the administration of a monoamine denervator such as TBZ. The present data indicate that the serotonergic inhibitory effect on the CA activity in the choroid plexus may be less predominant than that of TBZ and acetazolamide.

5-Hydroxytryptophan↗
PubMed1991

Magnetic resonance imaging of cavernous sinus cavernous hemangiomas.

Radiological findings of surgically verified cavernous hemangiomas of the cavernous sinus are presented with special reference to the appearance in magnetic resonance imaging. Differences in radiological features of the cavernous sinus cavernous hemangiomas and intracerebral cavernous hemangiomas are discussed.

Adult↗
PubMed1991

Growth of totally thrombosed giant aneurysm within the posterior cranial fossa. Diagnostic and therapeutic considerations.

We report a case in which growth of a totally thrombosed giant aneurysm of the posterior cranial fossa was demonstrated by computed tomography (CT) scans repeated after 4 years. A magnetic resonance (MR) image demonstrated an onion-skin-like, laminated structure within a calcified wall. The laminated structure had developed around an old thrombosis, without any communication to the flowing blood. It showed intensities indicating recent clots, revealing that the giant aneurysm had grown by recurrent intramural hemorrhage rather than by intraluminal accumulation of thrombotic materials. This case illustrates that totally thrombosed giant aneurysms still have the potential of growth.

Cerebral Angiography↗
PubMed1991

Choriocarcinoma of the septum pellucidum: case report.

A case of choriocarcinoma of the septum pellucidum is presented. The patient, a 6-year-old boy, demonstrated high levels of human chorionic gonadotropin in his urine, serum, and cerebrospinal fluid, and precocious puberty. The physical conditions and laboratory data returned to normal after surgical removal of the tumor, whole brain irradiation, and chemotherapy. Currently, there is no evidence of recurrence at 5 months after surgery.

Brain Neoplasms↗
PubMed1991

Ectopic retinoblastoma within the 3rd ventricle: case report.

Ectopic intracranial retinoblastomas are rare. These tumors usually occur in the pineal, parasellar, or suprasellar regions several years after the successful treatment of ocular retinoblastomas with no evidence of direct extension or distant metastasis. We report here a case of ectopic retinoblastoma occurring within the third ventricle. The tumor was surgically excised by the transventricular approach. Ectopic retinoblastomas exhibit greater differentiation than one would expect to observe in a metastatic lesion of this tumor. The distinction of ectopic retinoblastomas and metastasis from ocular retinoblastomas is important, since ectopic retinoblastomas, unlike metastasis, can be successfully managed by intensive therapy including radical excision.

Cerebral Ventricle Neoplasms↗
PubMed1991

A huge intracranial xanthogranuloma in the middle cranial fossa: case report.

Xanthogranulomas of the dura presenting with clinical symptoms are rare. We report here a case of a huge dural xanthogranuloma in the middle cranial fossa, which caused hemiparesis through marked displacement and stenosis of the middle cerebral artery. Although such tumors usually arise in association with histiocytosis X or familial hyperlipoproteinemia, the present case was not associated with these diseases.

Aged↗
PubMed1991

Characterization and modification of brain activity with deep brain stimulation in patients in a persistent vegetative state: pain-related late positive component of cerebral evoked potential.

A series of eight patients in a persistent vegetative state (PVS) were subjected to chronic deep brain stimulation (DBS) for the purpose of promoting recovery from the PVS. The characteristics of the brain activity in these patients were evaluated from the late positive component of the cerebral evoked potential in response to painful stimuli (pain-related P250). While any neurological scoring system for the comatose state includes evaluations of motor reactions to painful stimuli, the pain-related P250 is unique in terms of its ability to assess the cortical responsiveness to painful stimuli directly and quantitatively without involving functions of the motor system. It was found that the pain-related P250 was more or less depressed in patients in a PVS. It was repeatedly demonstrated in four patients, however, that the pain-related P250 could be transiently increased by preceding stimulation of the mesencephalic reticular formation. Furthermore, a persistent increase in the pain-related P250 was produced in these four patients following chronic DBS of the mesencephalic reticular formation or nonspecific thalamic nuclei for more than 6 months, and this was correlated with the clinical improvements. These results imply that responsiveness at the cortical level to pain is depressed in the PVS. It also appears that some fraction of the depression may, however, be functionally produced and potentially reversible.

Brain↗
PubMed1991

Treatment of thalamic pain by chronic motor cortex stimulation.

All forms of therapy, including chronic stimulation of the thalamic relay nucleus, can provide satisfactory pain control in only 20%-30% of cases of thalamic pain syndrome. In order to develop a more effective treatment for thalamic pain syndrome, we investigated the effects of stimulation of various brain regions on the burst hyperactivity of thalamic neurons recorded in cats after deafferentiation of the spinothalamic pathway. Complete, long-term inhibition of the burst hyperactivity was induced by stimulation of the motor cortex. Based on this experimental finding, we treated seven cases of thalamic pain syndrome by chronic motor cortex stimulation employing epidural plate electrodes. Excellent or good pain control was obtained in all cases without any complications or side effects. During the stimulation, an increase in regional blood flow of the cerebral cortex and thalamus, a marked rise in temperature of the painful skin regions, and improved movements of the painful limbs were observed. These results suggest that thalamic pain syndrome can be most effectively treated by chronic motor cortex stimulation.

Cerebrovascular Circulation↗
PubMed1991

Embolization of intramedullary spinal arteriovenous malformation fed by the anterior spinal artery with monitoring of the corticospinal motor evoked potential--case report.

Intramedullary spina AVMs fed by the anterior spinal artery cannot be embolized without risking unacceptable motor deficits, since the feeding arteries may supply the corticospinal tract (CST). An 8-year-old boy underwent successful embolization of such an AVM under general anesthesia using intermittent infusion of embolic material with monitoring of the CST integrity with the corticospinal motor evoked potential (MEP). This case illustrates the value of corticospinal MEP monitoring during therapeutic procedures under general anesthesia which risk interrupting the blood supply to the CST.

Arteries↗
PubMed1991

Intradural extraosseous chordoma in the foramen magnum region. Case report.

Chordomas that are entirely extraosseous and intradural are extremely rare. The tumors described in the literature were observed mostly in the prepontine region. This is the first case reported of an intradural extraosseous chordoma occurring in the foramen magnum region. The tumor was totally excised. The distinction between an intradural extraosseous chordoma and a classic chordoma is important from a clinical viewpoint because of the potential for complete surgical excision and a more benign growth pattern.

Adult↗
PubMed1991

[Ultrastructural findings of arachnoid cysts and epithelial cysts].

There may be several kinds of pathological conditions in the cystic lesion which are clinically diagnosed as benign intracranial cysts on CT scan. Light and electron microscopic studies on cyst walls were important in the differential diagnosis of benign intracranial cysts. We have studied 5 cases of intracranial arachnoid cysts and two epithelial cysts using the light and electron microscopy. Five cases of intracranial arachnoid cysts included two children and three adults (three females and two males). Three cases of them were localized in the middle cranial fossa, one case in the anterior and middle cranial fossa and one case in the lateral ventricle, giving headache and convulsion as the initial complaints. As for the epithelial cysts, one was localized at the para-collicular area complaining enlarged head and swollen anterior fontanelle and the other of four years was located in the fourth ventricle with headache and ataxic gait. On CT all of them demonstrated diffuse low density areas in both the arachnoid and the epithelial cysts without communicating findings between the cystic cavities and subarachnoid space on metrizamide CT cisternography. The arachnoid cyst walls were basically similar in structure to the normal arachnoid membrane and composed of elongated epithelial cells like the arachnoid cell and the connective tissues with lamellar collagen fiber bundles. However, 3 of the 5 cases had only fibrous tissues without epithelial cells. The inner sheath of the arachnoid cyst walls was composed of one or several layers of the arachnoid cells with flattened and relatively electron-dense cytoplasm on electron micrograph. They had a lot of elongated process and were tangled with each other, making large extracellular spaces between them. Below the electron dense arachnoid cells, compact packed cells with interdigitation partly demonstrated intercellular contacts such as numerous desmosomes and tight junctions. In those intercellular spaces collagen fibers and microfibrils were observed. The cells contained abundant cytoplasmic microfibrils and numerous organelles. They were separated from numerous collagen fibers and fibroblasts by non continuous basal lamina under the epithelial cells. Epithelial cyst wall had a layer of cuboidal or columnal epithelium in the inner layer of cyst wall. Those epithelial cells demonstrated granules having positive in PAS and mucicarmine stain in their cytoplasm. On electron microscopical study epithelial cells revealed a lot of microvilli and coating materials on the surface of them without cilia. The basement membranes were well developed under the epithelial cells separated from the connective tissues. In the intercellular clefts of the epithelial cells tight junctions and interdigitations were recognized.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Oedema fluid formation within contused brain tissue as a cause of medically uncontrollable elevation of intracranial pressure: the role of surgical therapy.

In patients with focal cerebral contusions, medical therapies have generally been advocated unless haemorrhages significantly contributing to the elevated intracranial pressure (ICP) exist. We report here several lines of clinical evidence which indicate that (1) enormous amount of extracellular oedema fluid is formed within contused brain tissue, (2) the formation of extracellular oedema fluid within contused brain tissue alone can be a cause of medically uncontrollable elevation of ICP and (3) surgical excision of the contused brain tissue provides excellent control of the elevated ICP in such patients. The excision of contused brain tissue appears to be the only therapy currently available to alleviate the formation of extracellular oedema fluid in cerebral contusions. We believe that, if ICP is elevated primarily by extracellular oedema due to cerebral contusions and the elevated ICP is medically uncontrollable, surgical excision of contused brain tissue should be carried out without delay regardless of the size of associated haemorrhages.

Body Fluids↗
PubMed1990

A new mapping study of superoxide free radicals, vascular permeability and energy metabolism in central nervous system.

To study the role of free radicals in various pathophysiologies in the central nervous system (CNS), we have introduced a new simultaneous mapping technique of superoxide free radicals, vascular permeability and energy metabolism. The detection of superoxide anion in the CNS is based on the 380 nm chemiluminescence of 2-methyl-6-phenyl-3,7-dihydroimidazo [1,2-alpyrazin-3-one(CLA-phenyl)] upon reaction with superoxide in the frozen tissue section. The results show topographical relationships between activation of superoxide free radicals, increased vascular permeability, and changes of hydrogen transport system in the energy metabolism (Fig. 2). Prolonged formation of superoxide free radicals in the white matter without vasogenic oedema and necrotic tissue are interesting as a mechanism of progression of secondary tissue damage in ischaemic insults.

Animals↗
PubMed1990

Cellular swelling during cerebral ischaemia demonstrated by microdialysis in vivo: preliminary data indicating the role of excitatory amino acids.

When rapid cellular swelling occurs, water moves from the extracellular space (ECS) into the cells and the concentration of ECS markers which do not move into the cells increases. Cellular swelling during cerebral ischaemia has therefore been demonstrated in vivo as an increase in ECS markers which is measurable with intracerebral electrodes. We attempted to detect the cellular swelling by brain microdialysis employing a similar principle. Dialysis probes were placed in the hippocampus, and perfused for 20 min with 14C-sucrose as an ECS marker. The probes were subsequently perfused without 14C-sucrose and the dialysate concentration of 14C-sucrose was determined at 1-min intervals. The dialysate concentrations of 14C-sucrose suddenly became elevated 1-3 min after the onset of cerebral ischaemia, indicating the occurrence of cellular swelling. The present technique is useful because it enables the mechanism of cellular swelling to be analyzed by observing the effects of pharmacological agents administered through a dialysis probe. Preliminary data indicating the role of excitatory amino acids in producing cellular swelling during cerebral ischaemia are presented as an example.

Amino Acids↗
PubMed1990

Survival and fibre outgrowth of neuronal cells transplanted into brain areas associated with interstitial oedema.

The influence of interstitial oedema on the survival of fetal raphe cells transplanted into serotonin (5-HT)-denervated rats and the fibre outgrowth from these cells was investigated. Fetal raphe cells were transplanted into the corpus callosum in which long-lasting interstitial oedema had been induced by intracisternal kaolin injection. The 5-HT and 5HIAA levels in the corpus callosum were restored to their maximum within 5-6 weeks post-transplantation regardless of whether interstitial oedema was induced or not. Furthermore, it was appeared that the presence of interstitial oedema even facilitated fibre growth as demonstrated by the 5-HT immunohistochemistry and the restoration of the 5-HT and 5-HIAA levels in brain areas distant from the transplantation sites. These results imply favourable effects of interstitial oedema on the survival of transplanted raphe cells and their fibre outgrowth.

Animals↗
PubMed1990

Effect of diltiazem and thromboxane A2 synthetase inhibitor (OKY-046) on vessels following experimental subarachnoid hemorrhage.

In order to examine the functional changes in the vascular smooth muscle, the effects of a thromboxane A2 synthetase inhibitor (OKY-046) and a calcium channel blocker (diltiazem) on vessels following subarachnoid hemorrhage, and the contractile activity of cerebral vessels with various vasoactive agents, were investigated by studying isometric tension recordings in rings of cat basilar artery. The maximum contractile activities of the vessels in response to noradrenalin and adrenaline during the course of subarachnoid hemorrhage were significantly less than those in the control group. On the other hand, the maximum contractile activity of the vessels in response to prostaglandin F2 alpha on the seventh day following subarachnoid hemorrhage was significantly augmented compared with that in the control group. A significant decline in the relaxation of responsiveness to diltiazem during the course of subarachnoid hemorrhage was observed compared with that of diltiazem in the control group. This responsiveness to vasoactive agents was not influenced by the application of OKY-046. The present study reveals functional changes in vascular smooth muscle exposed to subarachnoid hemorrhage in response to vasoactive agents and a calcium entry blocker. Thromboxane A2 may not be a significantly influential factor in the present results. It is suggested that cerebral vasospasm may well be related to functional changes of the arterial wall, which appear to be associated with derangement of the mechanisms of smooth muscle constriction and dilatation based on organic changes.

Animals↗