Biomedical subjects

T Kayama

Publications and source records attributed to T Kayama.

At least 91 records · Page 5Linked to original sources

PubMed1995

[A case of multiple cerebral mycotic aneurysms treated with endovascular surgery].

A case of multiple mycotic cerebral aneurysms successfully treated with endovascular surgery is reported. A nine-year-old boy who has suffered from hypertrophic obstructive cardiomyopathy and active infectious endocarditis in the mitral valve developed sudden consciousness disturbance and convulsion. Computerized tomography revealed subarachnoid hemorrhage with subcortical hematoma in the left parietal lobe. Angiography demonstrated four aneurysms at the distal part of the middle cerebral artery on both sides. Since his physical status had been deteriorating, it was difficult to undergo a usual surgical operation. Therefore, endovascular surgery was performed. The catheter was super-selectively advanced to the parent artery of the left posterior parietal artery aneurysm which seemed to be the hemorrhagic source, and the embolization was performed using platinum coils and liquid embolization material. Angiography after embolization showed that the aneurysms had been successfully occupied by the materials while the aneurysm of the right anterior parietal artery had not responded antibiotic therapy. Therefore the second embolization was carried out to the parent artery of the aneurysm of the right anterior parietal artery one month later. The patient had no neurological deficit after embolization and no aneurysms have been detected by the follow-up angiogram after the second embolization. An endovascular approach might be an alternative useful treatment for cases in which the patient has, deteriorated so much that it is considered difficult to perform open craniotomy under general anesthesia.

Aneurysm, Infected↗

PubMed1994

[CT and MR imaging findings of sphenoidal masses].

CT and MR imaging findings of 57 sphenoidal masses were retrospectively reviewed to assess the possibility of differential diagnosis between them. Various kinds of masses such as pituitary adenoma, epipharyngeal cancer, mucocele, chordoma, chondroma, chondrosarcoma, distant metastasis, multiple myeloma, fibrous dysplasia, craniopharyngioma, hemangiopericytoma, giant cell tumor, primary sphenoidal cancer, malignant melanoma, leukemia, histiocytosis X, and giant cell tumor were included in this series. CT scanning was performed in all cases, while MR images were obtained in 48 cases using a spin-echo pulse sequence. The relative density of the masses, bony changes and calcification were evaluated on CT, and on MR images, signal intensity of the masses relative to the normal gray matter, contrast enhancement and extension/contour were evaluated. Although no single feature appeared to be specific to the masses, detection of calcification on CT, identification of the normal pituitary gland as deformed or displaced on T1-weighted images, signal intensity on T2-weighted images, and extension of the masses seemed to be useful and should be examined in terms of their ability to assist in differential diagnosis. Finally, accommodative classification of sphenoidal masses primarily based on presumed origin or mode of extension was attempted.

Adolescent↗

PubMed1994

Gamma knife radiosurgery of a series of only minimally selected metastatic brain tumours.

From December 1991 to October 1992, 77 lesions in 25 consecutive patients were treated with Gamma Knife radiosurgery. Thirteen patients (52%) had multiple metastases up to sixteen lesions and twelve patients had a single metastasis. The volume of the largest tumour treated was 12.5 cm3. Karnofsky performance status (KPS) of the patients was 20-90% (mean 70). Marginal tumour dose given was 18 to 35 Gy (mean 26.1 Gy) in 30 to 90% isodose line according to the tumour volume and site. All but two patients were followed by MRI or CT scan repeatedly for a minimum of 6 month or to death. All but one of the tumours were locally controlled. Seventeen patients died during follow up and in four death was due to remote CNS metastases. The median survival for this minimally selected group of patients was 8.5 months, and the median survival for the patients with a single metastasis was 10.5 months. In patients with multiple metastases the median survival reached only 2.5 months but in 11 patients out of 13 patients neurological symptoms and signs improved or stabilized shortly after radiosurgery.

Adult↗

PubMed1994

Multicentric glioma studied with positron emission tomography: a case report.

Positron emission tomography (PET) studies of a multicentric glioma case were undertaken using 11C-methionine (Met) and 18F-fluorodeoxyuridine (FUdR). Met-PET revealed high accumulating lesion in both the left and right hemispheres, whereas in the FUdR-PET, the lesion on the right showed marked accumulation, but not that on the left. For both foci, the histologic diagnoses were anaplastic astrocytoma, but the lesion on the right showed higher density of undifferentiated tumor cells than that on the left. PET studies using Met and FUdR are effective in delineating the proliferative potential of glioma cells, which otherwise cannot be determined by histopathologic studies.

Brain↗

PubMed1994

Contrast-enhanced MR imaging of dural sinus thrombosis: demonstration of the thrombosis and collateral venous channels.

In order to study the role of Gd-DTPA-enhanced MR imaging in dural sinus thrombosis, precontrast and postcontrast imaging using Gd-DTPA in three patients with clinically unsuspected dural sinus thrombosis was reviewed. Comparisons were made with cranial CT scanning and cerebral angiography. Compared to CT, the postcontrast T1-weighted images more clearly revealed thrombus in the dural sinuses as a nonenhanced central area of intermediate intensity (but not flow void) surrounded by an enhanced rim. MR imaging also demonstrated secondary changes, including the presence of collateral venous channels and venous infarction.

Adult↗

PubMed1994

Multiple transcripts of the neurofibromatosis type 1 gene in human brain and in brain tumours.

1. Neurofibromatosis type 1 is a common hereditary disorder characterized by the presence of multiple neurofibromas and café-au-lait spots, and is frequently associated with intellectual handicaps and brain tumours. The gene responsible for neurofibromatosis (the NF1 gene) codes for a protein of 2818 amino acids, termed neurofibromin, which has a domain related to mammalian ras GTPase-activating protein. 2. The NF1 gene gives rise to multiple transcripts generated by alternative splicing, that encode neurofibromin and its isoforms. These include type I mRNA coding for neurofibromin, type II mRNA coding for neurofibromin containing the insertion of 21 amino acids in the GTPase-activating protein-related related domain and mRNA coding for an N-terminal isoform lacking the GTPase-activating protein-related domain (N-isoform). 3. In the present study, the relative levels of mRNAs encoding type I, type II and N-isoform were determined by S1-nuclease mapping analysis in human brain tissue and in primary brain tumours obtained from patients with tumours unrelated to neurofibromatosis type 1. 4. These three mRNAs were expressed in all ten brain tumours and in every region of the brain examined, with the highest levels found in the cerebellum. Type I mRNA was the predominant form in the human brain except for the pons, whereas type II mRNA was predominantly expressed in eight out of ten primary brain tumours. 5. In contrast, N-isoform mRNA was similarly expressed in normal brain tissue and brain tumours. 6. These findings suggest that neurofibromin and its isoforms have important physiological roles in the human brain and that the altered expression of type I and type II mRNAs in brain tumours may be related to the tumorigenesis.

Adult↗

PubMed1994

Multilobulated cystic formation in the brain stem with Benedikt's syndrome: case report.

A 26-year-old man presented with an unusual multilobulated cystic formation in the brain stem with normal pressure hydrocephalus, followed by fluctuating cyst volume and Benedikt's syndrome. Ventriculoperitoneal shunting to relieve the hydrocephalus caused an increased cystic size, resulting in worsened neurological deficits. Cystectomy and an additional shunt resolved the symptoms. Immunohistochemical and electron microscopic examinations of the surgical specimen revealed no epithelial lining but numerous astrocytic processes on the luminal surface, probably resulting from expansion of the cyst. This case suggests that cystectomy before shunt emplacement is recommended in similar cases.

Adult↗

PubMed1994

[Follow-up study of malignant astrocytomas showing complete response after initial treatment].

The prognosis for patients with malignant astrocytomas is still poor. The identification of groups of patients with good prognostic factors should be helpful in selecting the treatment strategies. In general, important prognostic factors are thought to be the extent of surgical resection required, age, performance status, duration of symptoms, location, and pathological tumor grade. The purpose of this present study is to evaluate the prognosis of patients with complete response (CR), that is, complete disappearance of the tumor mass in the contrast enhancement of computerized tomography (CT) scan after initial treatment. An additional purpose is to examine the effect of factors such as pathological tumor grade, location, age of patient, and the extent of surgical resection in achievement of CR. The subjects of the study were 81 patients with supratentorial malignant astrocytomas (45 males, 36 females) treated with surgical resection and radiochemotherapy in our division since 1980, and followed up for more than 5 years. There were 57 anaplastic astrocytomas (WHO grade III) and 24 glioblastomas (WHO grade IV). The extent of surgical resection and the response to the therapy were evaluated by CT scans. The Kaplan-Meier method was used in generating survival plots. Twenty-two cases (27%) showed CR at the end of the initial treatment, and the other 59 cases (73%) showed Non CR. Fifteen cases (26%) among 57 grade III patients and 7 cases (29%) among 24 grade IV patients showed CR. Tumor locations of CR cases were exclusively superficial with the exception of one case that involved deep structure. Average age of CR cases and Non CR cases were 34.4 and 49.7, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Neoplasms↗

PubMed1994

[A case of intracranial osteochondroma originating with psychomotor epilepsy].

A 28-year-old woman was admitted to our clinic due to psychomotor epilepsy. Craniogram, CT scan demonstrated a calcified lesion in the frontal, parasagittal region. MR proton images showed a mixed hyper-and hypodense lesion. The tumor originated from the frontal bone and was totally removed using airdrill safely. Histological findings revealed osteochondroma originating in the frontal bone is rare, and diagnostic procedures and surgical management of this tumor are discussed.

Adult↗

PubMed1993

Neonatal medulloblastoma.

A 9-day-old female presented with a large infra- and supratentorial medulloblastoma was treated by surgery, irradiation and chemotherapy. The infant suffered from vomit a few days after birth. She was hospitalized shortly thereafter, when head enlargement was noted. A CT scan taken on admission disclosed a large mass lesion in the cerebellum, extending to the pineal portion, and marked hydrocephalus. At the age of 14 days, the patient underwent ventriculoperitoneal shunting. When she was 67 days old, the tumor was radically resected. The histopathological diagnosis was medulloblastoma. Post operatively, she was irradiated with 30 Gy to the whole brain and 20 Gy to the tumor site. As chemotherapy, ACNU, 1-(4-amino-2-methyl-5-pyrimidinyl-3-(2-chloroethyl)-3-nitrosourea 1 mg/kg was administered twice per 6 weeks. On discharge at 7 months, her only neurological deficit was nystagmus. One week later, she could not move her legs and was readmitted. A CT scan showed no intracranial changes, but the spinal cord was swollen at Th12-L5 level. Myelography demonstrated a filling defect at the L3-5 level. Following irradiation of the spinal cord, the paraparesis gradually improved. However, her general status was deteriorating and a follow up CT scan revealed recurrence of the intracranial tumor. The patient died at the age of 9.3 months which is longer survival time than previous reported one. Neonatal brain tumors are rare, and there have been only 24 cases of neonatal medulloblastoma. The prognosis for these patients is extremely poor, regardless of treatment. Surgery, radiation and chemotherapy for neonatal medulloblastoma are discussed.

Brain Neoplasms↗

PubMed1993

Thyroxine 5-deiodinase in human brain tumors.

To determine whether human brains contain deiodinating pathways, we studied the activity of T4 5-monodeiodinase (5-D) in 20 human brain tumors obtained intraoperatively, including astrocytoma (10), meningioma (4), oligodendroglioma (2), glioblastoma (2), medulloblastoma (1), and malignant lymphoma (1). Mitochondrial-microsomal fractions prepared from these tumor tissues were used as the source of T4 5-D. Each sample was incubated with 32.2 nmol/L T4 and 30 mmol/L dithiothreitol at 37 C for 90 min. T4 5-D activity was measured by the production of rT3 from T4 with a RIA. T4 5-D activity was found in 6 of 10 astrocytomas, 2 oligodendrogliomas, 1 of 2 glioblastomas, and 1 malignant lymphoma. This activity depended on protein concentration, incubation time, incubation temperature, and pH of the incubation mixture. It was also heat labile. T4 5-D was not inhibited by 1 mmol/L propylthiouracil, but was inhibited by iopanoic acid and aurothioglucose in a dose-dependent manner. The apparent Km and maximum velocity for T4 5-D at 30 mmol/L dithiothreitol were 106.6 nmol/L and 22.7 pmol/mg protein.h, respectively. These data suggest that human gliomas (and probably malignant lymphomas) contain T4 5-D activity, which is similar to type III enzyme activity in the rat. T4 5-D may regulate the intracellular concentration of thyroid hormone in gliomas.

Adult↗

PubMed1993

Huge multilobular cavernous angioma in an infant: case report.

The authors encountered a rare case of multilobular cavernous angioma arising from the paraventricular region in an infant. Total resection of the angioma, which was 8 cm in diameter, was performed. The patient showed no neurological deficit. Although 22 cases in infants have previously been reported, this is the largest cavernous angioma and it is especially rare because of its multilobular configuration.

Brain↗

PubMed1992

Methylated cytosine level in human liver DNA does not decline in aging process.

In order to ascertain a generality of the age-dependent decrease in DNA methylation level among different mammalian species, methylated cytosine contents in human liver and spleen DNA at different ages have been determined using high performance liquid chromatography (HPLC). Unexpectedly, the liver DNA revealed no appreciable decline with age while the spleen DNA showed a slight reduction. It indicates that a decrease of methylation level in genomic DNA is not a common denominator of age-related changes in mammals.

Adolescent↗

PubMed1992

Treatment results by uneven fractionated irradiation, low-dose rate telecobalt therapy as a boost, and intraoperative irradiation for malignant glioma.

The prognosis of malignant glioma is extremely poor. We applied conventionally fractionated irradiation combined with 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), uneven fractionated irradiation with ACNU, low dose rate telecobalt therapy as a boost, and intraoperative irradiation against 110 malignant gliomas to investigate the efficacy of these methods as alternative treatments for malignant glioma. Although local tumor control by uneven fractionated irradiation was better than that by the other methods, no significant improvement was obtained in survival rates. As a result of multiple regression analysis, age and histology were major factors for survival rates, and the difference of treatment methods was not important. Both low-dose rate telecobalt therapy as a boost and intraoperative irradiation showed little advantage because of the high risk of brain necrosis associated with them.

Adolescent↗

PubMed1992

Radioresponse and prognosis of malignant glioma.

Radioresponse and prognosis of 91 malignant gliomas were studied to examine the efficacy of radiotherapy. There was no case of complete response. No statistically significant difference was observed among the prognoses of patients with various radiation methods. General survival rate was significantly higher than relapse-free survival rate both in astrocytoma grade III and in glioblastoma. This means that the retreatment after relapse is exceedingly important in any malignant glioma. In comparison with reported resection alone data, the efficiency of radiotherapy was evident in astrocytoma grade III and a part of glioblastoma; cases with minimal or no contrast enhanced area (CEA) in CT scans prior to irradiation. Poor radioresponders of glioblastoma with CEA should be reoperated.

Adolescent↗

PubMed1992

Overexpression and amplification of alpha-PDGF receptor gene lacking exons coding for a portion of the extracellular region in a malignant glioma.

Overexpression of the alpha-Platelet Derived Growth Factor Receptor (alpha-PDGF) gene was detected in a case of malignant glioma. This overexpression was accompanied with amplification of rearranged alpha-PDGF receptor gene. We have isolated a cDNA for the transcript derived from the amplified receptor gene. Characterization of the cDNA revealed a deletion of 243 nucleotides coding for 81 amino acids in the extracellular region of the receptor. This in-frame deletion removed a part of the immunoglobulin-like domains in the extracellular region of the receptor. Analysis of the amplified alpha-PDGF receptor gene in the glioma indicated that exons coding for the 81 amino acids were lost by a gene deletion. The gene amplification was also detected in macroscopically normal cortex adjacent to the glioma from the same patient. However, the amplified gene in the macroscopically normal cortex had no major gene rearrangement. These data suggest that the overproduction of structurally altered alpha-PDGF receptor may take part in the onset and the development of malignant glioma.

Exons↗

PubMed1992

Amplification of alpha-platelet-derived growth factor receptor gene lacking an exon coding for a portion of the extracellular region in a primary brain tumor of glial origin.

In a primary brain tumor of glial origin, we found overexpression of the alpha-platelet-derived growth factor (alpha-PDGF) receptor mRNA. Southern blot analysis of the gene revealed amplification of the rearranged alpha-PDGF receptor gene in the glioma. A cDNA coding for an aberrant transcript from the amplified receptor gene was obtained and characterized. Partial nucleotide sequence analysis of the cDNA revealed a deletion of 243 nucleotides coding for 81 amino acids in a portion of the immunoglobulin-like domains of the extracellular region of the receptor. cDNA polymerase chain reaction (PCR) of the total cellular RNA in the glioma indicated that more than 80% of the transcripts have a deletion of 243 nucleotides. Analysis of a PCR-amplified DNA fragment derived from the amplified alpha-PDGF receptor gene in the glioma revealed that an exon coding for the 81 amino acids was removed by a 2.1 kb gene deletion. We also found amplification of the alpha-PDGF receptor gene in macroscopically normal cortex adjacent to the glioma from the same patient. The amplified gene in the macroscopically normal cortex has no major gene deletion, suggesting that gene amplification is not sufficient for the development of malignant gliomas.

Amino Acid Sequence↗

PubMed1991

Brain tumors predominantly express the neurofibromatosis type 1 gene transcripts containing the 63 base insert in the region coding for GTPase activating protein-related domain.

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder. A part of the gene for NF1 was cloned and its deduced protein has a domain functionally related to mammalian ras GTP-ase-activating protein (GAP). Human tissues examined express two types of NF1 mRNAs: an originally identified species of NF1 mRNA (type I) and another one containing the 63 base insert in the region coding for GAP-related domain (type II). However relative levels of both mRNAs seem to change under certain conditions. Human brain expresses type I mRNA predominantly, while type II is preferentially expressed in most primary brain tumors (13/16 tumors analyzed). We suggest that higher levels of type II mRNA may be related to the genesis of brain tumors.

Adult↗