Biomedical subjects

T Yamashima

Publications and source records attributed to T Yamashima.

At least 73 records · Page 4Linked to original sources

PubMed1992

Cerebral vasospasm with elevated creatine phosphokinase following surgery of unruptured arteriovenous malformation.

Delayed cerebral vasospasm associated with marked elevation of serum creatine phosphokinase (CPK) is reported. A 21-year-old man with unruptured arteriovenous malformation (AVM) in the left temporal lobe developed postoperative symptomatic vasospasm lasting for 2 weeks. A postoperative computerized tomography scan showed intraventricular hematoma without subarachnoid hemorrhage in the basal cistern. On day 5 after surgery, the patient developed motor aphasia due to marked vasospasm around the bifurcation of internal carotid artery. On day 7 and 8, serum CPK was elevated as high as 1175 and 1376 IU/l, respectively. On day 35 when he had completely recovered from cerebral vasospasm both clinically and angiographically, the level of CPK was normalized. The causative factors of symptomatic cerebral vasospasm following surgery of unruptured AVM associated with CPK elevation are discussed.

Adult↗

PubMed1992

Gadolinium-DTPA enhancement of dural structures on MRI after surgery.

Gadolinium-DTPA enhanced MRI was examined before and after surgery in 14 patients with particular attention to the enhancement of falx cerebri, tentorium cerebelli and dura mater. A marked enhancement was observed in 2 falx and 2 tentorium before surgery, whereas it was observed in 7 falx, 9 tentorium and 11 dura after surgery. Among 6 falx, 7 tentorium and 12 dura showing increased enhancement after surgery, 2 falx, 3 tentorium and 8 dura showed marked enhancement which was not observed before surgery. A small amount of subdural haemorrhage during surgery is known to heal as subdural neomembrane with capillaries. An increased enhancement of dural structures conceivably derives from the extravasation of Gd-DTPA through capillaries involved in the subdural neomembrane. In the postoperative MRI, the enhancement of dural structures should be taken into consideration.

Adolescent↗

PubMed1992

Traumatic subdural hygroma: pathology and meningeal enhancement on magnetic resonance imaging.

Five patients with traumatic subdural hygroma are reported with reference to its pathology and meningeal enhancement on magnetic resonance imaging. Hygromas showed initially iso- and, later, high intensity on both T1- and T2-weighted images compared with the intensity of the cerebrospinal fluid. In all cases of the thick hygromas, magnetic resonance imaging with gadolinium diethylene-triamine-pentaacetic acid showed meningeal enhancement. Intravenously injected radioisotope immediately flowed into the hygromas, but computed tomographic cisternography and gross inspection during the surgery showed no evidence of an influx of cerebrospinal fluid into the hygromas. Microscopic examination of the enhanced meninges revealed vascularized neomembrane with numerous fenestrations and pinocytosis underneath the dura mater. It is suggested from these data that the subdural neomembrane is associated with the development of the traumatic subdural hygromas. Meningeal enhancement would be useful to clarify the growing mechanism of traumatic subdural hygromas.

Aged↗

PubMed1992

Expression of cell adhesion molecule E-cadherin in human arachnoid villi.

Calcium-dependent epithelial cell adhesion molecules designated as E-cadherin (also known as uvomorulin or L-CAM) were identified in human arachnoid villi by immunoblotting and immunocytochemical analyses using a monoclonal antibody HECD-1 raised against human mammary carcinoma MCF-7 cells. Immunoblot analysis showed that HECD-1 recognizes E-cadherin with a molecular weight of 124 kD. In all arachnoid cells of an arachnoid villus, E-cadherin was detected by immunolight microscopy within the cytoplasm rather than the cellular boundaries as seen in the control group. Furthermore, the extent of expression by immunolight microscopy varied from portion to portion. The expression was usually weak in the syncytial cluster which was ultrastructurally composed of tightly juxtaposed cells characterized by few extracellular cisterns and numerous cell junctions, while it was intense in the reticular cluster and the surface layer which were ultrastructurally characterized by abundant extracellular cisterns and smaller numbers of cell junctions. The cells of the reticular cluster and the surface layer contained more free ribosomes than those of the syncytial cluster. Immunoelectron microscopy showed that E-cadherin was localized not only to the opposing plasma membranes and the cytoplasm around the free ribosomes or the rough endoplasmic reticulum but also to the extracellular cisterns. As the expression of E-cadherin was closely related to the arachnoid cells adjacent to the cerebrospinal fluid pathway, it is suggested that, instead of the cell junctions, E-cadherin may play an important role in the flexible adhesion of arachnoid cells even in the presence of the cerebrospinal fluid.

Adolescent↗

PubMed1992

[A case of malignant glioma associated with verbal recent memory disturbance due to left hippocampal atrophy; case report].

Verbal recent memory disturbance was observed in a patient with a malignant glioma associated with left hippocampal atrophy. A 25 year-old male was admitted because of seizures. CT scan and MRI showed enhanced mass lesions in the left temporal lobe associated with ipsilateral hippocampal atrophy. Neurological examination disclosed right homonymous hemianopsia, word amnesia, alexia, agraphia and acalculia. Neuropsychological examination disclosed verbal recent memory disturbance, which consisted of impaired recall of the precisely memorized words after some interruption. Although hippocampal lesions are known to be often associated with cerebrovascular disease, hippocampal atrophy due to brain tumor is quite unusual. This case suggested that the left hippocampus is closely related to verbal recent memory. Hippocampal atrophy in this case conceivably derived from the decreased arterial flow due to perifocal edema or obstructive hydrocephalus.

Adult↗

PubMed1991

Anatomical variations of the straight sinus on magnetic resonance imaging in the infratentorial supracerebellar approach to pineal region tumors.

Anatomical variations of the straight sinus (SS) were examined on magnetic resonance imaging (MRI) in 108 control cases and five cases with a pineal region tumor. The data of the latter were compared with the operative findings in the infratentorial supracerebellar approach. In the 108 control cases, the length of the SS was 51 +/- 5.2 mm. The angle of the SS to the nasion-tuberculum sellae line, the tuberculum sellae-inion line, and the nasion-inion line was 51 +/- 6.7 degrees, 44 +/- 5.0 degrees, and 47 +/- 5.0 degrees, respectively. The SS was inclined 1.4 +/- 4.5 degrees posteriorly to the bregma-inion line. The anatomical relationship between the SS and the corpus callosum was subgrouped into three types: in the common type (63%), the extended line of the slope of the SS is tangential to the upper aspect of the splenium of the corpus callosum; in the high-angle type (26%), the extended line is far above the tangent line; and in the low-angle type (11%), the extended line is far below the tangent line. The operative field was restricted by the steeply inclined tentorium in the case of the high-angle type, and the tumor was located much lower than the direction of the operative approach. In contrast, the tumor was easily exposed in the center of the wide operative field in the cases of low-angle type. The present study suggests that the preoperative MRI analysis of the angle of the SS is indispensable before taking the infratentorial supracerebellar approach to the pineal region tumors.

Adolescent↗

PubMed1991

Symptomatic intrasellar arachnoid cyst: case report.

A case of a large symptomatic intrasellar arachnoid cyst with suprasellar extension is reported. A 53-year-old man was admitted because of decreased visual acuity. Magnetic resonance imaging showed a large intrasellar cyst extending into the suprasellar cistern, with compression of optic nerves. The intensity of the cyst was identical to that of the surrounding subarachnoid space on both T1-, T2-, and proton density-weighted images. Transsphenoidal surgery was performed, but subsequent refilling of the cyst required additional transcranial surgery. Analysis of the cerebrospinal fluid-like cystic fluid revealed high levels of protein and pituitary hormones. Histological study revealed that the cyst wall was composed of connective tissue and arachnoid cells, which were ultrastructurally characterized by a number of desmosomes. Diagnostic, surgical, and pathological features of intrasellar arachnoid cysts are discussed.

Arachnoid Cysts↗

PubMed1991

Immunohistochemical study of erythropoietin in cerebellar hemangioblastomas associated with secondary polycythemia.

Although cerebellar hemangioblastomas are known to be associated with secondary polycythemia, the cellular derivation of erythropoietin (EPO) in hemangioblastomas still remains obscure. Specimens from 18 patients with cerebellar hemangioblastomas were immunohistochemically studied using anti-EPO monoclonal antibody. Eight cases of brain tumors, including 2 meningiomas, 2 medulloblastomas, 2 glioblastomas, and 2 metastatic brain tumors were studied as controls. In 9 of 18 cases, EPO-positive cells were scattered around the capillaries and were ultrastructurally shown to be mast cells. These cases were not, however, associated with secondary polycythemia. In contrast, the stromal cells were positive for EPO in 3 cases. Among them, one was associated with secondary polycythemia. Furthermore, one-half of the control cases of brain tumor contained EPO-positive mast cells. Accordingly, it was suggested that mast cells (or small granulocytes) have little relationship to the release of EPO; however, some stromal cells might release EPO with a resultant polycythemia.

Adolescent↗

PubMed1991

A histological and flow cytometric study of dog brain endothelial cell injuries in delayed radiation necrosis.

The pathogenesis of delayed cerebral radiation necrosis was studied histologically and biochemically in 25 dogs with special attention to vascular endothelial cell injuries. The dogs were sacrificed 3 to 30 months after irradiation with a single dose of 15 Gy to the head. Brain specimens were appropriately fixed for light and electron microscopic studies, and capillary endothelial cells were isolated for flow cytometric study. The endothelial cells were stained with acridine orange, then the cell ratios in the reproductive phase (S + G2 + M) were investigated with flow cytometry. Thereafter, Feulgen hydrolysis and computer analysis of the hydrolysis curves were performed to examine the qualitative changes in deoxyribonucleic acid (DNA) of endothelial cells after irradiation. Under light microscopy, spongy degeneration with small cell infiltration was observed, especially in the frontal white matter, at 6 months after irradiation. At 9 months, necrotic foci appeared and developed until 15 months after irradiation. Blood vessels around the necrotic area showed luminal narrowing with endothelial hyperplasia and proliferation. At 30 months, no fresh necrotic lesions were observed. Under electron microscopy, endothelial cells of capillaries and small vessels around the necrotic area showed an increase of pinocytosis, and in the nuclei there was an increase of infoldings and euchromatin. The cell ratios in the reproductive phase were 14.5% to 23.3% (maximum at 9 months) in the irradiated group compared to 6.4% in the control group. The rate constant of apurinic acid production, a parameter correlating with DNA transcriptional activity, was minimum at 3 months and maximum at 9 months after irradiation. The data suggest that impairment of the microcirculation plays an important role in the pathogenesis of delayed radiation necrosis, and that the time of necrosis occurrence closely correlates with the cell cycle of vascular endothelial cells.

Animals↗

PubMed1990

Histological, ultrastructural and chromatographical discrimination of phospholipids in meningiomas.

Phospholipids in meningiomas were studied by light and electron microscopy, and by high-performance liquid chromatography. They were microscopically demonstrated in six of the ten cases by Sudan III staining after the fixation with potassium dichromate. However, the conventional ultrastructural fixation with glutaraldehyde and osmium tetroxide failed to confirm phospholipids, as most of them were dissolved during dehydration. In contrast, the specimens pretreated with tannic acid before osmication ultrastructurally retained phospholipids which were represented by multilamellar bodies or ribbon-like rings. Both were found in 23 of the 30 cases within the cytoplasm, among the plasma membranes and in the extracellular matrices. The outermost lamella or ribbon showed a direct continuity from the neighbouring plasma membranes of the cytoplasm or the mitochondria. The multilamellar bodies showed an overall distribution, while the ribbon-like rings were predominantly distributed around the psammoma bodies. Precipitation of hydroxyapatite crystals within the ribbon-like rings resulted in matrix minerals of psammoma bodies. Chromatographical analyses of meningiomas disclosed phospholipids including phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, sphingomyelin and phosphatidyl inositol in that order. Psammomatous meningiomas contained a higher percentage of phosphatidyl serine than non-psammomatous tumors. Ultrastructural study of synthetic phospholipids adequately treated with tannic acid showed that the multilamellar bodies were similar to phosphatidyl choline, while the ribbon-like rings were similar to phosphatidyl serine. The role of phospholipids in meningiomas is discussed.

Adult↗

PubMed1990

Repetitive intratumoral hemorrhage in medulloblastoma. A case report.

An 8-year-old girl experienced five repeated hemorrhagic episodes around the cerebellar vermis. Surgical specimens histologically showed abnormal vascular components invaded by tumor cells. Autopsy disclosed medulloblastoma disseminating in the subependymal zone of the ventricles. An atypical clinical course is reported with special attention to the cause of hemorrhage.

Cerebellar Neoplasms↗

PubMed1990

Neurotoxicity of local administration of two nitrosoureas in malignant gliomas.

The neurotoxicity of local administration of nitrosoureas in malignant gliomas was investigated clinicopathologically. Twenty patients were entered into this study: 13 were treated with 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) and 7 with methyl 6-[3-(2-chloroethyl-3-nitrosoureido]-6-deoxy-alpha-D-glucopyranoside (MCNU). On the average, a single dose of 20 mg of ACNU was administered 15 times, for a total dose of 295 mg in each case, while a single dose of 11 mg of MCNU was given 2 times, for a total dose of 24 mg. These nitrosoureas provoked greater toxicity when the administration dose was larger or the indwelling multiperforated Silastic basket was in direct continuity with the ventricle or the basal cistern. Usually ACNU was well tolerated, whereas MCNU induced marked brain edema. Side effects consisted of headache, nuchal stiffness, vomiting, motor weakness, and cranial nerve palsy for ACNU, and headache, vomiting, abnormal respiration, and arrhythmia for MCNU. Pathological changes were represented by capsule formation, spongy degeneration and reactive gliosis of adjacent white matter, occlusion of neighboring arteries, and demyelination of cranial nerves in the patients treated with ACNU, while they were represented by focal brain necrosis in two patients treated with MCNU. The differences in neurotoxity of ACNU and MCNU conceivably derive from the different blood-brain delivery of these drugs.

Adolescent↗

PubMed1990

Radiation necrosis of the optic chiasm, optic tract, hypothalamus, and upper pons after radiotherapy for pituitary adenoma, detected by gadolinium-enhanced, T1-weighted magnetic resonance imaging: case report.

A 26-year-old woman was treated for a prolactin secreting pituitary adenoma by surgery and radiotherapy (5860 rads). Fourteen months later, she developed right hemiparesis and dysarthria. A T1-weighted magnetic resonance imaging scan using gadolinium contrast showed a small, enhanced lesion in the upper pons. Seven months later, she had a sudden onset of loss of vision, and radiation optic neuropathy was diagnosed. A T1-weighted magnetic resonance imaging scan showed widespread gadolinium-enhanced lesions in the optic chiasm, optic tract, and hypothalamus. Magnetic resonance imaging is indispensable for the early diagnosis of radiation necrosis, which is not visualized by radiography or computed tomography.

Adenoma↗

PubMed1990

Pulmonary surfactant-like multilamellar bodies in human arachnoid villi.

Human arachnoid villi adequately treated with tannic acid before osmication ultrastructurally disclosed highly ordered multilamellar bodies in all of the 6 subjects studied. The multilamellar bodies were varied considerably in size and shape, but often showed a fingerprint-like appearance. They were found in the intercellular space, extracellular cisterns or microcores and within the cytoplasm of arachnoid cells. The number of lamellae in a single lamellar body ranged from 3 to 20, and the periodical width of the lamellae was approximately 5.0 nm. The outermost lamella sometimes showed a direct continuity with the adjacent plasma membranes of the cytoplasm or mitochondria. As multilamellar bodies were ultrastructurally quite similar to pulmonary surfactant, they were assumed to be related to the lubricated flow or absorption of the cerebrospinal fluid.

Adolescent↗

PubMed1990

An ultrastructural and immunohistochemical study of extracellular matrix in meningiomas.

Extracellular matrix of meningiomas was studied by light and electron microscopy with the aid of immunohistochemical techniques. Special attention was paid to the distribution of type I, III, IV, V collagens and laminin with a comparison between meningothelial and fibroblastic types. Connective tissue fibers and basement membrane were not found among the tumor cells in the meningothelial type, but were found in the fibroblastic type. The immunolocalizations were consistently demonstrated extracellularly, but were not within the cytoplasm. Type I, III and V collagens were usually demonstrated in the fibrous septum in the meningothelial type, while they were localized among the tumor cells in the fibroblastic type. Furthermore, type IV collagen and laminin were demonstrated within the vascular walls or around the syncytium in the meningothelial type, while they were localized among the tumor cells in the fibroblastic type. In both types the expression of type IV collagen and laminin was closely related to the distribution of basement membrane. Although meningothelial and fibroblastic meningiomas showed quite different distribution of extracellular matrices, the profile of collagen types expressed by these two basic types was essentially the same. The cellular derivation of meningiomas was discussed with particular attention to the structure of human arachnoid villi and meninges.

Collagen↗

PubMed1989

Cranioplasty with hydroxylapatite ceramic plates that can easily be trimmed during surgery. A preliminary report.

The author has designed new cranioplastic materials to reconstruct a skull defect of moderate size in both the convexity and the suboccipital region. A domed and elliptic plate measuring 50 x 75 mm in diameter, 12 mm in the maximum height and 5 mm in thickness was made from hydroxylapatite ceramics. The latter comprise Ca10(PO4)6(OH)2 as mammalian bone minerals and are characterized by an excellent biocompatibility and biostability resulting in bony fusion. Hydroxylapatite ceramic plates can be easily trimmed during surgery to closely fit the skull defect. There were no adverse reactions nor resorption of the implants.

Durapatite↗

PubMed1989

Experimental intracranial hypertension following cisternal injection of various blood components.

Intracranial pressure (ICP) was recorded in 30 dogs which underwent cisternal injection of blood, serum, red blood cells (RBC). RBC ghosts, oxyhemoglobin or bilirubin. The amount of injection was 8-10 ml of blood or an equivalent volume of blood components. Blood or RBC showed a sustained ICP of 15 to 25 mmHg, and RBC ghosts caused a slight transient rise of ICP. In contrast, oxyhemoglobin or bilirubin induced marked intracranial hypertension up to 60-80 mmHg which was associated with frequent pressure waves. Histological examination disclosed aseptic meningitis at the base of the brain and inflammatory changes in the floor of the fourth ventricle after the injection of oxyhemoglobin or bilirubin. It is suggested that the breakdown products of RBC might be causative factors of the intracranial hypertension following subarachnoid hemorrhage.

Animals↗

PubMed1989

Liberation of eosinophil granules in the inner capsule of chronic subdural hematomas.

The role of eosinophilic infiltration in the inner capsule was studied in 35 consecutive cases of chronic subdural hematomas. The eosinophilic infiltration in the inner capsule was microscopically observed in 10 of the 22 cases which were associated with the infiltration in the outer capsule. The majority of eosinophils were ultrastructurally fully granulated and contained numerous glycogen granules. In contrast, some eosinophils were undergoing marked cellular disruption or necrosis with a resultant liberation of secretion granules. This was confirmed in all of the 10 cases. The free granules were closely apposed to fibrin strands which were interwoven with a number of disintegrating inflammatory cells. The inner capsule was usually adhered by massive fibrinous clot and the remaining liquified hematoma contained low levels of fibrinogen and high levels of FDP. Secretion granules of the eosinophils were previously demonstrated to contain plasminogen or cytotoxic material. Accordingly, the eosinophils conceivably contribute to both the fluidity of subdural clot and the disruption of inflammatory cells in chronic subdural hematomas.

Aged↗