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Biomedical subjects

M Kowada

Publications and source records attributed to M Kowada.

At least 109 records · Page 6Linked to original sources
PubMed1990

[Positron emission tomography (PET) study in patients with meningiomas].

Regional hemocirculation and metabolism were evaluated in five patients with meningiomas using positron emission tomography (PET). Histological diagnoses were: two cases of meningotheliomatous type, one hemangiopericytic type, one fibroblastic type, and one transitional type. Regional cerebral blood flow (rCBF), blood volume (rCBV), oxygen extraction fraction (rOEF), and metabolic rates of oxygen (rCMRO2) and glucose (rCMRG1) were measured with 15O2, C15O. 15O2, and 18F-fluorodeoxyglucose tracers. For the quantitative analysis, regions of interest were delineated on tumors, the peritumoral region, and the contralateral gray matter in comparison with age-corresponding 5 malignant gliomas and 5 normal volunteers. Tumor hemocirculatory parameters (rCBF: 57.2 +/- 22.6 ml/100 ml/min, rCBV: 7.95 +/- 3.27 ml/100 ml, mean + SD, n = 5) were markedly higher than those of the contralateral gray matter (p less than 0.05 by a Student-t test). The high values were consistent with angiographic findings of tumor staining and with abundant tumor vessels demonstrated by pathological examination. rCMRO2 was 2.15 +/- 0.80 ml/100 ml/min, which were comparable to those of the contralateral gray matter. Tumor rCMRG1 showed 4.76 +/- 2.37 mg/100 ml/min; the values of two cases were similar to the respective gray matter. The raised metabolic rate (rCMRO2/rCMRG1) therefore suggests rather aerobic glycolysis as compared with gliomas. Low rOEF (0.26 +/- 0.16) reveals an excessive blood flow beyond oxygen demand of the tumor. In the peritumoral regions, rCBF and metabolism fell slightly but rOEF reached a level similar to the contralateral gray matter, possibly due to hemocirculatory stasis caused by intracranial hypertension; in contrast, an unmatched reduction of rCBF and rCMRO2 implies tumor cells infiltration in gliomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Ventriculoperitoneal shunts with the use of pressure-adjustable valve in the management of hydrocephalus].

Sixteen patients with hydrocephalus of varied etiology who underwent ventriculo-peritoneal shunts utilizing pressure-adjustable valves were reviewed, and the usefulness of the pressure-adjustable valve in the management of hydrocephalus was evaluated. Before shunting all patients had CT evidence of hydrocephalus with Evans' Index greater than 30%. High-, medium- and low-pressure settings were chosen in 3, 11 and 2 patients respectively, according to the CSF pressure as measured during lumber puncture or ventricular drainage. Following the shunting procedures with programmable pressure valves, hydrocephalus was alleviated with Evans' Index being 27% on the average, as evaluated by CT scans. Such clinical symptoms as disturbed consciousness, dementia and increased intracranial pressure all subsided. There were no mortality, infection or revision during the follow-up period of 5 to 16 months. Of particular note was that, among these 16 cases, there were three illustrative cases in which programmable pressure valves were found useful in coping with newly developed subdural effusion and low-intracranial-pressure syndrome, by manually adjusting the valves to higher pressure settings.

Adult↗
PubMed1990

[Automated image processing by PACS as a simple tool for designing craniotomy; synthesis of sagittal reconstructed CT images and cerebral angiograms].

Software has been developed to produce sagittal images of the brain recontracted from axial CT slices and automatically superimpose them on the lateral views of cerebral angiograms. A commercially available system for digitization, processing, display and computer storage of film radiographs (EFPACS-500) was used in the present studies. Axial CT scans are obtained in either 3, 5 or 10mm thicknesses parallel to the base line at the 10 degree angle to the OM line, and processed into the digital storage. Plain skull films and subtracted angiograms, on which two reference points on the same base line for superimposition were marked prior to processing, are also digitized and stored in the optical disk. On each CT slice, the ratio is calculated of a lesion's longitudinal length to the midsagittal distance of the head. By simply adjusting a linear cursor, which is parallel to the base line, to the highest and the lowest levels of the lesion, the sagittal image with the lesion clearly depicted is automatically reconstructed. And on this image an angiogram can be superimposed automatically simply by indicating two reference points on the base line on both images. The resulting images have markedly facilitated simple designing of craniotomy for intracranial lesions by graphically indicating their locations along with cerebral vessels in a lateral view.

Adult↗
PubMed1989

[Prognostic significance of regional blood flow, blood volume, oxygen extraction fraction, and metabolic rates of oxygen and glucose as measured by positron emission tomography in patients with gliomas].

We tested clinical significance of hemocirculatory and metabolic values and ratios as determined by positron emission tomography (PET) in twenty-three patients with cerebral gliomas. Regional cerebral blood flow (rCBF), blood volume (rCBV), oxygen extraction fraction (rOEF), and metabolic rates of oxygen (rCMRO2) and glucose (rCMRGl) were measured prior to treatment using PET with 15O2, C15O, 15O2, and 18F-fluorodeoxyglucose tracers. For the quantitative analysis, regions of interest were delineated on tumor regions including peak activity, the contralateral gray and white matter. The regional values and the ratios of tumor/gray matter and tumor/white matter were compared to performance status (PS) according to the five functional grades system which are defined by the Japan Society for Cancer Therapy, tumor progression-free time (PFT), survival time (ST) from the time of the PET study, regardless of type of therapy. As with rCMRGl, the tumor values and the ratios of tumor/gray matter and tumor/white matter correlated significantly with PS (tumor/gray: p less than 0.05, tumor/white: p less than 0.01). Both the gray rCBF and the tumor/gray rCBF ratio had close relation with PS and/or PFT (p less than 0.05). The gray matter rCMRO2 and the tumor/gray matter rCMRO2 ratio related significantly (gray matter: p less than 0.01, tumor/gray: p less than 0.05) to each clinical parameter of PS, PFT, and ST. These indicate that values and ratios as determined by PET can be useful in predicting the prognosis of glioma patients.

Adolescent↗
PubMed1989

Sequential PET studies in neuro-Behçet's syndrome.

A case of neuro-Behcet's syndrome is presented with sequential positron emission tomography (PET) studies. Regional cerebral blood flow (rCBF) and oxygen consumption (rCMRO2) were decreased in the brain lesion; however, on follow-up studies 3 months after steroid therapy rCBF and rCMRO2 had increased in the lesion, which demonstrated the reversibility of this disease. Such monitored improvement may accurately reflect the early stage of the disease and its response to steroid therapy.

Behcet Syndrome↗
PubMed1989

Intracranial invasion of scalp carcinoma. Report of five cases.

Among 10 patients with squamous cell carcinoma admitted to our hospital, 5 showed intracranial invasion and 4 died with regrowth of intracranial tumour 9 to 24 months after incomplete extirpation of tumour. We reviewed our experience in the management of advanced scalp carcinoma, from neurosurgical and neuroradiological points of view. Dural invasion failed to be removed completely because of involvement of the middle part of the superior sagittal sinus. Therefore, total resection, facilitated by early detection prior to intracranial invasion, is mandatory for successful treatment of these scalp carcinomas.

Aged↗
PubMed1989

Microspectrofluorometric evaluation of single- and double-stranded DNA in short-term cultured human glioma cells.

Seven cerebral gliomas in short-term culture were studied by microspectrofluorometry and acridine orange staining to assess their nuclear content of single- and double-stranded DNA. Benign gliomas showed a diploid DNA pattern, whereas malignant gliomas revealed a higher frequency of DNA aneuploidy and hyperploidy. The content of single-stranded DNA remained relatively low in benign gliomas; however, that in malignant gliomas varied widely. After ACNU treatment, the double-stranded DNA histograms showed S-phase-specific accumulation in all cases but 1 with increasing concentrations of ACNU. The single-stranded DNA content decreased considerably in 2 cases, which responded well to chemotherapy and showed clinical amelioration.

Adult↗
PubMed1989

Composed dynamic topography for spike and sharp wave.

We reported two kinds of dynamic topographies. In one, an interspike interval histogram and a computerized topography of the EEG basic activity were composed. In the other, spike and sharp wave characteristics were composed of an isopotential topography. These topographies enabled us to observe serial changes in epileptic discharge dynamically by 1 msec.

Brain Mapping↗
PubMed1989

Cellular substrates for epileptiform activity induced by repeated tetanic stimulation in hippocampal slices.

Using intact and transected hippocampal slices, we investigated the relationship between CA3 and CA1 subfields in the generation of stimulus train-induced bursting. In intact slices, spontaneous bursts in CA3 always preceded those in CA1, whereas after-discharge bursts in CA3 followed those in CA1 when it was possible to distinguish differences in the burst onset. After transection between CA3 and CA1, neither spontaneous nor triggered bursts could be induced or maintained in isolated CA1, where only small after-discharge bursts with higher bursting frequency were observed. Some of the mechanisms underlying the generation of these stimulus train-induced bursts are discussed.

Animals↗
PubMed1989

Ultracytochemical study of Ca2+-ATPase activity in isolated, superoxide-treated rat brains.

The relationship between changes in Ca2+-adenosine triphosphatase (ATPase) activity and plasma membrane damage was histochemically studied by enzymatic electron microscopy in rat brains with and without superoxide treatment. The brains were obtained from male Wistar rats after decapitation, and the control brains were examined immediately. Brains not treated with superoxide were incubated at 20 degrees C for 3, 6, or 12 hours. The superoxide-treated brains were immersed in a hypoxanthine-xanthine oxidase system for 20, 60, or 120 minutes. Ca2+-ATPase activity in the cerebral cortex and hippocampal CA1 was studied by the lead citrate method. Control brains showed Ca2+-ATPase activity in the membrane of the nerve cell body and dendrites, the basement membrane of endothelial cells, and the erythrocyte membrane. In untreated brains, enzymatic activity gradually decreased but was still detected after 12 hours. In those treated with superoxide, enzymatic activity gradually decreased but was still observed after 120 minutes in fragments of the plasma membrane. These findings show that the plasma membrane is more affected by treatment with superoxide than by decapitation itself, and that plasma membrane damage precedes the disappearance of Ca2+-ATPase activity. Residual Ca2+-ATPase activity does not necessarily imply reversibility of cerebral ischemia.

Animals↗
PubMed1989

[Radiochemotherapy-related changes in the brain parenchyma of glioma patients evaluated repeatedly by C15O2, C15O, 15O2, and 18F-fluorodeoxyglucose (FDG) PET].

The aim of this study was to evaluate effects of radiochemotherapy on blood flow and metabolism using C15O2, C15O, 15O2, and 18F-fluorodeoxyglucose positron emission tomography (PET). Conventional, external radiotherapy (180-200 cGy/5 fractions/week) using 60Co or a 10 MV linear accelerator was given in conjunction with chemotherapy of nimustine hydrochloride (ACNU) and tegafur (FT-207) in eight patients with gliomas. Regional cerebral blood flow (rCBF), blood volume (rCBV), oxygen extraction fraction (rOEF), oxygen consumption (rCMRO2), and glucose consumption (rCMRG1) were longitudinally examined before the treatment, and at an early stage (within one month) and a late stage (three to thirty-one months with a mean of 12 months) after radiochemotherapy. Contralateral gray and white matter to the tumor was selected as regions of interest (ROIs), because these portions were irradiated with larger doses compared to other brain parenchymal regions through parallel opposing fields. Maximum doses to the ROIs varied between 20 and 61 Gy. Calculated as a function of time-dose-fractionation, nominal standard doses (NSD) ranged from 566 to 1729 ret, and 344 to 1062 neuret; equivalent doses (ED) equaled 432 to 1327 rads. At the early stage, rCBF and rCBV increased in the contralateral gray and white matter; gray matter rOEF decreased significantly (p less than 0.05 by a paired-t test) from that of the pretreatment study, probably due to decompression of the tumor bulk and radiochemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Chemotherapeutic strategy in rat brain tumor cells resistant to ACNU using an in vitro colony formation assay].

Nitrosourea compounds have been widely used in the chemotherapy of malignant brain tumors, because of their blood-brain barrier permeability. However, drug resistance to nitrosoureas has been recently a major concern. Using an in vitro colony formation assay, intrinsic and acquired resistances to an anticancer nitrosourea, 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU), were analyzed in rat 9L and C6 glioma cells. 9L and C6 cells were treated with varying doses of ACNU for 2 hours. Ten days after, the cells were fixed and stained with crystal violet. Colonies consisting more than 50 cells were counted. The survival fraction following treatment is the ratios of colony efficiency of treated cells to the colony efficiency of untreated control cells. The dose-response curve for ACNU indicated the existence of a shoulder (Dq, quasithreshold dose) at doses and an exponential cell-killing at higher doses with D0(37% survival dose). Based on dose-response curves corresponding to multitarget single-hit model, 9L cells showed 7.4 microM, 2.9 microM, and 14 microM at Dq, D0, and SD10 (10% survival dose) values, respectively, whereas C6 cells showed respective values of 6.4 microM, 30 microM, and 75 microM. 9L cells had significantly less intrinsic resistance to ACNU than C6 cells at the p less than 0.005 level by a covariance analysis of the curves. As with changes of drug susceptibility after ACNU treatment, both parent cells were treated every other day (1, 5, and 10 repeated times) with various doses up to approximately 1% survival dose of the parent cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Analysis of regional blood flow, blood volume, oxygen and glucose metabolism in heterogeneous parts of untreated high grade gliomas using positron emission tomography (PET)].

A high resolution positron emission tomography (PET), HEADTOME III, has enabled us to visualize heterogeneous parts, i.e. viable, necrotic, and edematous portions in malignant gliomas, and to quantify regional hemocirculation and metabolism of the tumors using 15O and 18F-fluorodeoxyglucose tracers. Hemocirculatory and metabolic indices of regional cerebral blood flow (rCBF), blood volume (rCBV), oxygen extraction fraction (rOEF), oxygen consumption (rCMRO2) and glucose consumption (rCMRGl) were studied in eight patients with untreated malignant gliomas. Regions of interest (ROIs) in PET images were focused on lesions corresponding to contrast enhancing areas, central low density areas of the tumors, and peritumoral low density areas in CT scans. In the viable portion of the gliomas, rCBV (5.20 +/- 1.18ml/100ml, mean +/- SD, n = 8) was significantly higher than that of the contralateral gray matter (p less than 0.05), which is suggestive of high vascularity; rOEF (0.36 +/- 0.16) and rCMRO2 (1.66 +/- 0.45ml/100ml/min) values markedly decreased (p less than 0.05, p less than 0.01). On the other hand, rCBF (36.3 +/- 13.0ml/100ml/min) and rCMRGl (5.94 +/- 1.15mg/100ml/min) were similar to that of the contralateral gray matter. A relative dissociation between oxygen and glucose metabolism indicates anaerobic glycolysis in the energy metabolism of malignant gliomas. In the central low density area, rCBF, rCBV, rOEF, rCMRO2, rCMRGl values decreased significantly from the viable portion and the contralateral gray matter. rOEF was markedly reduced in the central low density area as compared with that of the peritumoral low density area. The rOEF reduction indicates that oxygen metabolism of gliomas is the first to fail, accompanied by autoregulatory impairment of vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Malignant astrocytoma following radiotherapy in pituitary adenoma: case report].

A case of malignant astrocytoma following radiotherapy for pituitary adenoma is presented in detail with a review of the literature. A 38 year-old housewife had developed a growth-hormone secreting pituitary adenoma, and received a total of 50 Gy at the pituitary region. Four years and six months later, she began suffering headache and vomiting. Computed tomography showed an extensive low density with ring enhancement in the right temporal region, corresponding to the previously irradiated field. A right frontotemporoparietal craniotomy was carried out, and a soft and reddish tumor was partially removed. The histological diagnosis was that of malignant astrocytoma. The patient was submitted to postoperative radiochemotherapy, receiving a total of 60 Gy, nimustine hydrochloride (ACNU), and tegafur (FT). Subsequently, after three months of clinical relief, she developed tumor regrowth, and died four months later. The present case fulfills the criteria for radiation-induced tumor established by Cahan et al.: A tumor location within irradiated area, no evidence of tumor prior to radiotherapy, a long latency period between radiation and tumor occurrence, and histological verification of the tumor. Thirty-nine cases of radiation-induced gliomas including the present case have been reported in the literature. It is noteworthy that the majority occur in the younger age bracket. Male preponderance is noted as it is in primary cerebral gliomas. The primary lesions for radiation frequently include leukemia and lymphoma. Craniopharyngioma, pituitary adenoma, and medulloblastoma etc are also included.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1989

[Surgical management of squamous-cell carcinomas arising in burn scar of the scalp].

A series of seven patients with squamous-cell carcinoma that arose in the area of an old scalp burn is presented, and the patient's profiles, surgical procedures and results are reviewed. In six patients, burn scar of the scalp caused by direct exposure to fire in their infancy was a pathogenesis underlying the development of the malignancy, and the time interval was estimated to be an average of 53 years. In five patients there was evidence of intracranial invasion of the carcinoma involving the dura mater and cerebral parenchyma, as revealed by neuroradiological examinations and surgery. All patients were treated by extensive excision of the lesion, and to cover defects of the scalp and cranium, a variety of reconstructive techniques were used involving advancement, transposition or free latissimus dorsi musculocutaneous flaps combined with microvascular anastomosis. Radiochemotherapy was undertaken additionally in some patients either before or after surgery. Complete excision was accomplished in two patients, in whom the carcinoma was found localized within the layer of the scalp or in the depth of the periosteum. The survival time in these patients ranged from 73 to 87 months. In contrast, incomplete resection was performed in the remaining five patients, in whom the dura mater had been invaded with simultaneous involvement of the middle part of the superior sagittal sinus. The outcome resulted in poor prognosis, and all the patients except one died in 9 to 24 months after surgery due to continuous growth of the tumor in the intracranial cavity. Therefore, total resection facilitated by early detection prior to intracranial invasion is mandatory for successful treatment of such scalp carcinomas.

Aged↗
PubMed1989

[Changes in the (11C-methyl)-L-methionine uptake index in gliomas following radiotherapy].

We have studied changes in the (11C-methyl)-L-methionine (C-11 Met) uptake index in six glioma cases subsequent to radiotherapy, using positron emission tomography (PET) to evaluate the effects of radiotherapy on the amino acid metabolism of the tumor. The uptake index of the tumor represented as a percentage of the total count in the atrial blood recorded during a period of 45 min, showed an average of 0.037% and 0.039% prior to and within two months after the therapy, respectively. Out of three cases where a fall in the index was seen, two cases showed tumor regression in the size of the contrast enhanced lesion measured by CT; all three cases had a relatively long period of clinical and neurological amelioration. However, following a short period of clinical improvement, the other three patients with a rise in the index showed no change or tumor progression on CT. These findings indicate that changes in the C-11 Met uptake index can be a sensitive and precise indicator for evaluating the effect of radiotherapy on gliomas.

Adult↗
PubMed1989

[Circumvention of ACNU-resistance in rat glioma cells by pretreatment with O6-methylguanine].

The chemotherapy of malignant brain tumors has been, only partially successful yet. Recently major concern is drug resistance, one of possible mechanisms of such drug resistance stems from inducible repair enzyme, especially in case of chloroethylnitrosoureas as ACNU or BCNU. We examined the changes of acquired resistance to ACNU in rat glioma cells by pretreatment with O6-methylguanine, which is a substrate for O6-methylguanine methyltransferase. ACNU-resistant (9L/AC) cells had established after 10 times treatments of ACNU. 9L/AC cells were pretreated with 2 mM O6-methylguanine for 2 hours, and subsequently challenged with increasing doses of ACNU for 2 hours. In vitro colony formation assay the survival fraction of 9L and 9L/AC cells ranged from 0.39 to 0.63 by 2-hour reaction of 1-3 mM O6-methylguanine. Based on the dose-response curve for ACNU in 9L/AC cells, by O6-methylguanine pretreatment (2 mM), ACNU-resistance decreased markedly to one-third, one-fifth, and one-two hundredth at 12, 24, 36 microM ACNU, respectively. In contrast, the survival of 9L cells against ACNU was similar under O6-methylguanine pretreatment or nontreatment condition. Therefore, ACNU-resistance is considerably related to DNA repair enzyme induction, and the substrates may potentiate the cell-killing effect of ACNU in the resistant glioma cells.

Animals↗