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T Sasajima

Publications and source records attributed to T Sasajima.

At least 73 records · Page 4Linked to original sources
PubMed1996

Inhibition of methionine uptake by cis-diamminedichloroplatinum (II) in experimental brain tumors.

cis-diamminedichloroplatinum (II) (CDDP) has been used both alone and in combination with other chemotherapeutics for cancer chemotherapy. Although CDDP acts primarily on DNA, it can also act at the tumor-cell membrane to inhibit methionine transport. The latter mechanism of CDDP is reported to have an important role as a chemical modulator in enhancing chemotherapeutic effects of 5-fluorouracil in tumor cells. We report here the effects of CDDP on methionine uptake in an in vivo brain-tumor model. C6 brain-tumor cells were stereotactically inoculated in the right basal ganglia of 6-week-old male Sprague-Dawley rats. Ten days after the inoculation, autoradiographic images were obtained using (14C-methyl)-L-methionine. The tracer uptake, represented as differential absorption ratio (DAR) and an acid-insoluble fraction (AIF), was measured in both brain tumors and normal brain with or without an intravenous injection of CDDP. The tumor/non-tumor DAR and AIF decreased significantly (P < 0.01, as determined by the Mann-Whitney U-test) after CDDP treatment, whereas the non-tumor DAR and AIF remained almost unchanged. These findings indicate that CDDP inhibits methionine uptake selectively in brain-tumor tissue and may therefore be a potent chemical modulator in the chemotherapy of brain tumors.

Absorption↗
PubMed1996

Early results of a reinforced biosynthetic ovine collagen vascular prosthesis for small arterial reconstruction.

The efficacy of a reinforced biosynthetic ovine collagen (RBOC) vascular prosthesis developed for small arterial reconstruction was assessed by examining 30 grafts in 29 patients with arteriosclerosis obliterans. The operative procedures performed were femorofemoral bypass in 2 patients, above-knee femoropopliteal bypass in 28 patients, and below-knee femoropopliteal bypass in 1 patient. Femoropopliteal bypass was simultaneously performed in two patients undergoing femorofemoral bypass using one or two grafts. The indications for surgery were intermittent claudication in 27 patients and to salvage the limb in 2 patients. The longest follow-up period was 49 months, and there were six graft failures, occurring 1, 1, 9, 17, 17, and 23 months after implantation, respectively; caused by compression of the graft from outside in two, infection in one, anastomotic intimal hyperplasia in one, and unknown factors in two. Thus, the primary cumulative patency rate for above-knee femoropopliteal bypass at 3 years was 83.7%, and the secondary patency rate was 91.2%. No aneurysmal change was observed. Moreover, the RBOC was able to be used without preclotting, and its handling and suturing characteristics were satisfactory. Our findings suggest that this vascular prosthesis may be an acceptable alternative for above-knee femoropopliteal bypass.

Aged↗
PubMed1996

Spinal cord ependymoma: a positron emission tomographic study with (11C-methyl)-L-methionine.

An intramedullary spinal cord ependymoma was studied by positron emission tomography (PET) using (11C-methyl)-L-methionine (11C-Met). MRI showed a homogeneously enhancing tumour at C6-T2 with cysts at its rostral and caudal ends. Sagittal PET images demonstrated high 11C-Met uptake in the solid portion of the tumour, particularly ventrally at C7-T2, where viable tumour cells proliferated in association with abundant perforating vessels. Met-PET would appear useful for delineating the viable portion of intramedullary ependymomas.

Aged↗
PubMed1996

Quantitative evaluation of neutral amino acid transport in cerebral gliomas using positron emission tomography and fluorine-18 fluorophenylalanine.

To elucidate the mechanism of large neutral amino acid (LNAA) transport in cerebral gliomas and to evaluate the clinical usefulness of positron emission tomography (PET) with fluorine-18 fluorophenylalanine (18F-Phe), we examined 18 patients with cerebral glioma using dynamic PET and 18F-Phe. By employing two-compartment model analysis, the influx rate K1, the efflux rate k2 and the distribution volume (Vd) of 18F-Phe were estimated in tumour tissue and contralateral normal grey matter. 18F-Phe showed increased accumulation in tumour tissue regardless of the grade of malignancy in all patients. The rate of uptake of 18F-Phe in high-grade glioma was significantly higher than in low-grade glioma (P <0.05). However, it was difficult to evaluate the tumour grade only from the 18F-Phe accumulation in individual cases. Values of K1 and Vd were significantly increased in the tumour tissue. The K1 value of the tumour tissue tended to decrease with increasing LNAA concentration in plasma. Therefore, influx of 18F-Phe into tumour tissue is mainly related to the carrier-mediated active transport. It is concluded that PET with 18F-Phe is of clinical value for tumour detection rather than assessment of tumour malignancy.

Amino Acids↗
PubMed1996

Long-term positron emission tomography evaluation of slowly progressive gliomas.

Non-invasive positron emission tomography (PET) was performed to identify changes in blood flow and metabolism, specific to early stages of tumour occurrence or recurrence. 2 patients with slowly progressive gliomas from early to late stages of tumour development were analysed by serial PET measurements of circulation and metabolism using 15O-gas and 18F-fluorodeoxyglucose. PET revealed a persistent depression of oxygen metabolism, as indicated by the regional oxygen extraction fraction or metabolic rate of oxygen, in the regions where tumours were later found. Abnormal blood flow and metabolism may precede the morphological changes detected by computed tomography (CT) in patients with gliomas.

Adult↗
PubMed1996

Re-endothelialisation in autogenous vein grafts.

OBJECTIVES: To clarify the course of re-endothelialisation (Re-E) in an entire graft and to establish the effect of immersion media for the preservation of endothelial cells. METHODS: Autogenous femoral veins of dogs were immersed in heparinised saline solution (n = 18) or heparinized autogenous blood (n = 18). After immersion, the grafts were implanted into bilateral femoral artery, and were retrieved 1 day to 4-8 weeks after implantation. RESULTS: For the grafts immersed in the heparinised saline solution, the values for % area of endothelial cell coverage before implantation, and at 1 day, 1 week, and 4 weeks after implantation were 44.9%, 6.2%, 14.5%, and 81.3%, respectively. For the grafts immersed in heparinised autogenous blood, the values were 73.5%, 20.6%, 79.2% and 95.5%, respectively. However, such relatively rapid speed of Re-E slowed down considerably after 1 week following implantation in this group. CONCLUSIONS: The use of heparinized autogenous blood is strongly recommended as a preparation media for autogenous vein grafts. Almost all of the endothelial cells fall away in the earlier period after implantation and regenerate multifocally and irregularly. Re-E is incomplete even at 8 weeks after surgery, and we suggest that the area of incomplete Re-E may develop into intimal hyperplasia.

Animals↗
PubMed1996

[Sequential analysis of the integrated images of PET, CT and MR in malignant brain tumors before and after radiotherapy].

11C-methyl-L-methionine (C-11 Met)PET, CT and MR imaging were performed in eleven patients with malignant brain tumors before and after RT to evaluate the usefulness of positron emission tomography (PET) in monitoring tumor response to radiotherapy (RT). The subjects included five cases of intracranial malignant lymphoma (ICML) and six cases of glioma. C-11 Met uptake by the tumor (T) and the contralateral gray matter (NT) was calculated on the PET images. The mean T/NT ratio of the ICMLs and gliomas changed from 2.33 and 1.87, respectively, before RT to 1.31 and 1.58, respectively, after RT.No significant difference was found between the T/NT ratios before and after RT in either the ICMLs or the gliomas (t-test). We tentatively defined the minimum T/NT ratio, 1.2, as the threshold between tumor and nontumor regions. Tumors with a ratio of 1.2 or more were imaged as "hot" (MET) and coincided with CT or MR image lesions which were visualized as contrast-enhancing (CE) and low-density (LD) or high-intensity (HI). The relationships between PET, CT and MRI lesions were classified as follows: Type I (MET < or = CE), Type II [CE < MET < LD (HI)], Type III [LD(HI) < or = MET]. MET lesions extending regionally ( > 1 cm) beyond the respective CT or MR image lesions were designated "MET-extension" and LD (HI) lesions protruding ( > 1 cm) beyond the MET lesions were recorded as "LD (HI)-extension" on the integrated images. The type II pattern of the MET areas in all five cases of ICML before RT had changed to Type I in one case, Type III in one case and Type II in three cases, after RT, while the two Type II patterns and four Type III patterns of the gliomas had converted to four Type II and two Type III patterns. These findings indicate that gliomas tend to invade into areas of peritumoral edema more than ICMLs. There were two ICML MET-extension sites in the cortex before RT, as opposed to two in the cortex, one in the basal ganglia, one in the thalamus, and one in the corpus callosum among the gliomas. On follow-up CT or MR images MET-extension (75%) had converted to a CE or LD (HI) region. Four ICML LD (HI)-extension sites before RT were found in periventricular white matter, versus one in the cortex and three in the white matter among the gliomas. LD (HI)-extension appeared to represent vascular edema because it decreased or diminished after completion of therapy. Sequential analysis of integrated C-11 Met PET, CT and MR images is useful in detecting the extent of tumor infiltration by ICMLs and gliomas, particularly at an early stage, and for evaluating the effect of RT in the treatment of both.

Adult↗
PubMed1996

[Pharmacokinetics of 99mTc-MAG3 and 131I-OIH: comparative study based on 2 compartment model analysis].

We studied 50 patients with mild to moderate renal dysfunction to compare pharmacokinetics of 99mTc-MAG3 with that of 131I-OIH. After simultaneous bolus injection of both 99mTc-MAG3 and 131I-OIH, 8-point venous blood sampling was performed from 2 to 44 min post injection. Aliquoted plasma samples were counted for radioactivity along with the injected standard to obtain % injected dose/ml plasma for each tracer. Using obtained time-concentration data, classical 2 compartment model analysis was performed for both tracers to obtain various pharmacokinetic parameters, including distribution volumes (Vds), inter-compartmental rate constants, and plasma clearance. In these parameters, Vd of central compartment, Vd at steady state, central to peripheral inter-compartmental rate constant, and plasma clearance were significantly larger for 131I-OIH. In all parameters, significant correlation was found between 99mTc-MAG3 and 131I-OIH. The best correlation was seen in plasma clearance (r = 0.891, p < 0.0001). Plasma clearance ratio (99mTc-MAG3/131I-OIH), however, showed weak but significant negative correlation with serum creatinine, although this correlation was not likely to affect the overall correlation of clearance between 131I-OIH and 99mTc-MAG3. From these results, we confirmed that 99mTc-MAG3 clearance could be used as an alternative to 131I-OIH clearance, although pharmacokinetic behavior of 99mTc-MAG3 was not exactly the same as that of 131I-OIH.

Adult↗
PubMed1996

[Usefulness and problems of high dose chemotherapy using CBDCA, VP-16, and MCNU with peripheral blood stem cell transplantation in pediatric malignant brain tumors].

The aim of this study was to evaluate efficacy of high dose chemotherapy and restoration of hamatopoiesis following peripheral blood stem cell transplantation (PBSCT). Three patients with pediatric malignant brain tumors (two medulloblastomas and one medullomyoblastoma) underwent high dose chemotherapy including CBDCA, VP-16, and MCNU with PBSCT. Postcontrast-MR images revealed no abnormal enhancing lesions after high dose chemotherapy in all patients. One patient with medulloblastoma has remained complete remission one year and seven months after the termination of treatment. Another patient with medullomyoblastoma died of respiratory distress syndrome one month after the second course of high dose chemotherapy. The other patient with medulloblastoma, which received PBSCT and high dose chemotherapy at the time of tumor recurrence after failure of initial treatment, suffered from multiple disseminated lesions five months after the treatment. PBSCT contributed prompt recovery from hematopoietic dysfunction in all patients. These results indicate that PBSCT may play an important adjuvant to chemotherapy and further offer a safer and more effective high dose chemotherapy in pediatric malignant brain tumor patients.

Adolescent↗
PubMed1996

[Femoropopliteal bypass for patients with arteriosclerosis obliterans].

In this paper the current technical trend for femoro-popliteal bypasses (FP) was discussed. There is a broad consensus that vascular prostheses such as Dacron or ePTFE are reliable alternatives to autogenous vein grafts (AVG) for FP above the knee (FPAK). However, AVG is employed for FP below the knee (FPBK), while there is no significant difference in long term patency between reversed vein and in situ vein grafts. Use of heparinized autogenous blood for preparation of AVG is superior to heparinized saline solution in the reendothelialization. The value for %-area of endothelial cell coverage in the AVGs is 20% at 2 hours after implantation, whereas 80% of the area is covered after one week. FPs for diabetic patients with intermittent claudication should be limited because there is a possibility of occurrence of isolated popliteal segment due to disease progression. 5-year primary cumulative patency rates of prostheses for FPAK and AVGs for FPBK are about 70%, justifying the strategy of using vascular prostheses for FPAKs.

Anastomosis, Surgical↗
PubMed1996

[Pulmonary aspergillosis: clinical findings and surgical treatment].

Between 1980 and 1995, 10 patients underwent thoracotomy for pulmonary aspergillosis. In six patients, hemoptysis and bloody sputum were the chief complaints. The other complaints were nonspecific. Six patients had a history of pulmonary tuberculosis, and two of those patients underwent upper lobectomy. Aspergillosis had developed in the residual space. A fungus ball was observed on the preoperative chest X-ray and CT scan films in seven patients. Lobectomy was done in three patients, segmentectomy in two, and partial pulmonary resection in four. The patients with lesions that had grown in the residual space underwent curettage with muscle plombage. Three patients underwent thoracoplasty. An additional operation was done in two patients because of poor residual lung expansion. No patient had recurrence. We conclude that surgical treatment should be based on symptoms and on pathological findings.

Adult↗
PubMed1996

[Repair of diaphragmatic hernia through the thoracoabdominal spiral incision].

Traumatic diaphragmatic hernia requires urgent surgical treatment. A 51-year-old female was injured in a speeding car. She had dyspnea, and resistance on the abdominal wall on physical examination. Intra-thoracic and abdominal visceral injury was suspected. A chest roentogenogram and CT scan revealed an obvious diaphragmatic herniation on the left which necessitated emergency operation. On the right semi-lateral position, left thoracoabdominal spiral incision was made through the 7th intercostal space. Good exposure of the chest and abdomen was easily obtained. Herniated organs and the abdominal cavity were thoroughly examined with ease. The diaphragm was repaired directly. She had an uneventful postoperative recovery, and was discharged in 17 days. Thoracoabdominal spiral incision offered an excellent operative exposure for the patient with a possible combined thoracic and abdominal visceral injury.

Female↗
PubMed1996

[Positron emission tomographic evaluation for frontal hypertrophic cranial pachymeningitis using 11C-methyl-L-methionine].

A case of frontal hypertrophic cranial pachymeningitis was presented with positron emission tomography (PET) using (11C-methyl)-L-methionine (11C-Met). A 55-year-old male developed right hemiparesis after generalized tonic convulsion one month prior to admission. MR images revealed patchy enhancement extending from the dura mater to the cerebral parenchyma surrounding high T2-weighted signal in the left frontal region. Left carotid angiogram showed atresia of the rostral superior sagittal sinus and obliteration of the cortical veins associated with compensatory venous channels coursing in the frontal deep white matter. PET demonstrated high 11C-Met uptake in the area corresponding to the enhancing lesion on the MR images. The ratio of lesion/normal cortex was 1.58 as an indicator of selective uptake in the lesion. The contralateral temporal gray matter was representative of a normal cortex. In contrast, 11C-Met did not accumulate in the frontal white matter where T2-weighted MR images showed abnormal high intensity lesion. This suggested that the frontal white matter lesion was derived from vasogenic edema due to venous infarction. The patient underwent an uneventful exploratory biopsy. The dura mater had proliferated to a thickness of 3.5mm and was tightly adherent to the left middle frontal gyrus. Microscopically, the thickened dura mater where the tracers had accumulated was composed of abundant collagenous fibers together with diffuse infiltration of inflammatory cells, including predominantly lymphocytes, plasma cells, and neutrocytes. The lymphocytes, which proved positive in both UCHL-1 and L26 staining, had no atypism. Histological findings corresponded to hypertrophic pachymeningitis. Met-PET clearly represented viable and infiltrative zones of inflammatory cells. The patient's neurological symptoms and signs gradually improved. Follow-up MR images three months after the surgery showed the enhancing lesion to be diminished and a marked regression of the vasogenic edema. Spatial determination of viable lesions permitting differentiation from biological inactive or vasogenic edema is an important guideline in selecting an appropriate surgical procedure in the diagnosis and treatment of hypertrophic cranial pachymeningitis. Met-PET would appear useful in delineating inflammatory lesions such as hypertrophic cranial pachymeningitis.

Carbon Radioisotopes↗
PubMed1996

Regional cerebral blood flow response in gray matter heterotopia during finger tapping: an activation study with positron emission tomography.

We examined regional cerebral blood flow response in a patient with gray matter heterotopia located beneath the sensorimotor cortex during a finger tapping task. We found regional cerebral blood flow was specifically increased during contralateral finger tapping. This indicated the possibility of functional differentiation of the ectopic neurons despite incomplete migration.

Adult↗
PubMed1996

[Surgical treatment of primary mediastinal tumors in children].

Twenty children with primary mediastinal tumor underwent surgical treatment. Ten patients had benign tumor and the other patients were malignant. Seven of ten patients with malignant tumor were neurogenic, and 3 patients were of germ cell tumor. In the clinical manifestation, 11 patients were asymptomatic. All of benign tumors were resected completely, but in a few patients with malignant tumors, the complete resection not possible. However, except for one patient with immature teratoma, all patients with malignant tumor have been surviving following postoperative chemotherapy and radiotherapy. Two infants with bronchogenic cyst were operated on their respiratory distress syndrome in emergency, and have been salvaged.

Adolescent↗
PubMed1995

Blood flow and metabolism of central neurocytoma: a positron emission tomography study.

BACKGROUND: New World Health Organization classifications have categorized central neurocytomas as neuronal tumors. The differential diagnosis between central neurocytomas and other tumors is important for selection of the optimal therapy modality for the management of intraventricular tumors. To characterize the pathophysiology and proliferating activity of central neurocytoma accurately, cerebral blood flow and metabolism in five patients with central neurocytoma were studied using positron emission tomography (PET). METHODS: Tracers used for the present study included C15O2, C15O, 15O2, and 18F-fluorodeoxyglucose (FDG). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), cerebral metabolic rate of oxygen (rCMRO2), and cerebral metabolic rate of glucose (rCMRGl) were quantitatively analyzed in tumor lesions and the contralateral gray matter. Four patients with central neurocytoma underwent a complete PET study, including all circulatory and metabolic parameters; one patient was studied with 11C-methyl-L-methionine and FDG tracers. RESULTS: Tumor rCBF and rCBV were higher than comparable values in the contralateral gray matter in three of four patients. This high level of perfusion corresponds to angiographic findings that show intense tumor staining in tumors fed by perforated arteries. Tumor rOEF and rCMRO2 were significantly lower than corresponding values in the gray matter (rOEF, P < 0.01; rCMRO2, P < 0.05 by Student's t test). Tumor rCMRGl ranged from 2.68 to 6.26 mg/100 ml/minutes and did not exceed contralateral gray matter values in any of the five patients. Tumor rCMRGl was significantly lower (P < 0.02) than the gray matter rCMRGl. One tumor exhibited a relatively high value of rCMRGl (comparable to gray matter rCMRGl), and increased in size 4 months after partial resection. No other tumors appeared during postoperative follow-up periods that ranged from 4 to 135 months. CONCLUSIONS: Circulation and metabolism parameters measured by PET offer insight into the biologic characteristics of central neurocytoma. Tumor rCMRGl may be an indicator of the proliferating activity in central neurocytoma.

Adult↗
PubMed1995

Positron emission tomographic assessment of cerebral hemocirculation and glucose metabolism in malignant glioma following treatment with intracarotid recombinant human tumor necrosis factor-alpha.

Cerebral hemocirculation and glucose metabolism in a malignant astrocytoma were repeatedly quantified before and after intracarotid injection of recombinant human tumor necrosis factor-alpha (rH-TNF) using positron emission tomography (PET). The patient received an intracarotid injection of a 3 x 10(4) U/m2 dose of rH-TNF three times over a two week period. PET was performed prior to and 24 hr after the first injection, and two weeks after the third injection. Prior to the first rH-TNF treatment, two lesions demonstrating high perfusion and hypermetabolism of glucose were noted in the right frontal and temporal regions. The frontal hypermetabolic lesion showed decreases in hemocirculation and metabolism 24 hr after the first injection and then increases beyond the pre-treatment level two weeks after the third treatment, whereas the temporal lesion remained unchanged during the follow-up period. No appreciable changes were noted in the adjacent cortex where rH-TNF was perfused, with the exception of a transient decrease in regional blood volume. Magnetic resonance images of the tumor showed no changes as a result of treatment with intracarotid rH-TNF. Intracarotid rH-TNF preferentially affects tumor tissue as opposed to normal cortex.

Astrocytoma↗