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Biomedical subjects

K Takakura

Publications and source records attributed to K Takakura.

At least 505 records · Page 28Linked to original sources

Combined treatment with chemotherapy and radiation therapy for intracranial germ cell tumors.

We analyzed our treatment results in 153 patients with histologically verified intracranial germ cell tumors and proposed classifying them into three therapeutic groups with good prognosis, intermediate prognosis, and poor prognosis. In this work, we selected patients treated with chemotherapy (cisplatin or carboplatin combinations) in each subgroup, and we discuss the role of chemotherapy in their treatment. Our combination chemotherapy regimens are: cisplatin-vinblastine-bleomycin, cisplatin-etoposide, and carboplatin-etoposide. We delivered these chemotherapies to the last 33 patients and compared their treatment results with those obtained in the previous 31 patients, who were treated with conventional radiation therapy alone. A combination with chemotherapy and a reduced dose of irradiation with local field was given to 7 patients with germinoma to increase the cure rate and reduce radiation-induced side effects, including anterior pituitary dysfunction. We obtained an excellent initial response to chemotherapy. The chemotherapy we delivered had significantly better effects in the group with intermediate prognosis, but not in the group with poor prognosis. More aggressive chemotherapy and radiation therapy should be given as the initial treatment.

Adolescent↗

Experimental evaluation of the beneficial effect of an antioxidant on cerebral vasospasm.

Based on the previously suggested hypothesis that generation of free radicals leading to lipid peroxidation is involved in the genesis of vasospasm following SAH, the therapeutic effect of an antioxidant on experimental vasospasm was examined. As an antioxidant suitable for this purpose, AVS(1,2-bis(nicotinamide)-propane) was used. Experimental SAH was induced in dogs by intracisternal injection of blood and subsequent changes in the basilar artery diameter was evaluated by angiography. First, intrathecal administration of AVS 3 days after SAH caused prompt resolution of pre-existing chronic vasospasm for 3-4 h. Next, the effect of continuous intravenous administration of saline (control) or AVS was started and continued for 4 days. In the control group, early and chronic spasm was observed on the daily angiography. In the AVS-treated group, early spasm was only moderately inhibited, but the occurrence of chronic spasm was remarkably suppressed in a dose-dependent manner. In these experiments, no adverse effect of AVS on the neurological or systemic conditions was observed. The data indicate that AVS may be beneficial in the treatment of vasospasm following SAH, thereby reinforcing the concept that generation of free radicals is involved in the genesis of vasospasm.

Animals↗

Chromosomal aberrations in normal human cells induced by the auger effect via Ca atoms.

PURPOSE: To quantify the Auger effect on chromosomal aberrations via Ca atoms in human cells. MATERIAL AND METHODS: Exponentially growing human normal fibroblasts (GM05389) were irradiated with 4.047 (CaK-P), 4.026 (CaK-L) and 4.067 (CaK-H) keV X-rays (corresponding to the resonance absorption edge of the Ca K-shell and slightly below and slightly above the edge, respectively) using synchrotron radiation at the photon factory (PF) of the High Energy Accelerator Organization located in Tsukuba. Chromosomal aberrations induced by the irradiation were analyzed by the premature chromosome condensation (PCC) method using calyculin A. The dependency of the chromosomal aberrations on the incubation time post 2 Gy irradiation was observed for each energy. Irradiation using 200 kVp conventional X-rays was also examined as a reference to CaK irradiation. RESULTS: (1) Soon after irradiation with 2Gy, the enhancement ratios of CaK-H X-rays to CaK-L X-rays were 1.21, 1.51 and 2.70 for breaks/gaps, isochromatid breaks and exchanges, respectively. The enhancement ratios of CaK-P X-rays to CaK-L X-rays were 1.82, 0.98 and 6.30, for breaks/gaps, isochromatid breaks and exchanges, respectively. (2) After a 6-hr incubation treatment post 2 Gy irradiation, the enhancement ratios of CaK-H X-rays to CaK-L X-rays were 1.59, 2.03 and 2.14 for breaks/gaps, isochromatid breaks and exchanges, respectively. The enhancement ratios of CaK-P X-rays to CaK-L X-rays were 1.69, 1.66 and 2.00 for breaks/gaps, isochromatid breaks and exchanges, respectively. (3) Soon after irradiation, the ratios of the efficiencies of CaK-P X-rays to those of 200 kVp X-rays were 1.74, 1.29 and 2.51 for breaks/gaps, isochromatid breaks and exchanges, respectively. And after a 6-hr incubation treatment, the ratios were 5.50, 1.93 and 1.81 for breaks/gaps, isochromatid breaks and exchanges, respectively. CONCLUSIONS: An effective enhancement of chromosomal aberrations, such as breaks/gaps, isochromatid breaks and exchanges, was caused by Ca K-shell ionization or excitation. Auger electrons emitted by Ca atoms in irradiated cells appear to have an important role in causing this enhancement. Comparing these efficiencies of chromosomal aberrations with those produced by 200 kVp conventional X-rays suggests un-repaired and complicated damage is induced by the X-rays around the Ca K-shell resonance absorption edge.

Calcium↗

Uterine deformity caused by surgery during pregnancy.

OBJECTIVE: The purpose of our study was to determine the cause of a unique deformity of the uterus, in which the cervix is elongated and appears fixed to the anterior abdominal wall. MATERIALS AND METHODS: Imaging from 2,558 consecutive MR studies of the pelvis of women were retrospectively reviewed for the simultaneous presence of elongation of the uterine cervix, angulation of the uterine isthmus just beneath the anterior abdominal wall, and vertical orientation of the long axis of the uterine corpus. RESULTS: Fourteen cases exhibited the uterine deformity; 13 of these cases had histories of cesarean section (CS) performed from 9 to 33 years (mean 18.2 years) previous to MRI. Among them, six patients had a history of multiple CS. The remaining case had a history of enucleation at 13 weeks' gestation of uterine leiomyoma, located at the anterior wall of the lower uterine segment. Thirteen patients had not become pregnant after the last CS (no. = 12) or the myomectomy (no. = 1). CONCLUSION: This unique uterine deformity strongly indicates a history of incision in the lower uterine segment especially at late gestational age. Since all but one patient with this deformity did not become pregnant after the last surgery, this deformity may be one reason for infertility after CS.

Abdominal Muscles↗

Increased cyclooxygenase-2 expression is correlated with suppressed antitumor immunity in cervical adenocarcinomas.

Cyclooxygenase-2 (COX-2) inhibition suppressed the growth of various tumors. The augmentation of antitumor immunity by increasing cytotoxic lymphocytes may be an important mechanism for COX-2 inhibition. Among cervical cancers, adenocarcinomas present more aggressive behavior and overexpressed COX-2. The expression of COX-2 and the CD8+ lymphocyte infiltrations were evaluated in this study by immunohistochemistry. We studied COX-2 expression and CD8+ lymphocyte infiltration in 55 women with cervical adenocarcinomas. COX-2 expression and tumor stromal CD8+ lymphocytes were evaluated by semiquantified methods. Tumor intraepithelial lymphocytes were counted under microscopic field of x200. Correlations between these data and other clinicopathologic features were investigated. Thirty-seven out of 55 (67.3%) cervical adenocarcinomas significantly expressed COX-2. Patients who died within 5 years showed higher percentage of COX-2 expression than survivors (100% vs 58.1%, P < 0.05). Victims also showed lesser intraepithelial CD8+ lymphocyte counts than survived patients (3.4 vs 26.4, P < 0.05). COX-2 expression and tumor intraepithelial lymphocyte count were reversely correlated with each other (correlation index: -0.38, P < 0.01). Up-regulated COX-2 expression and lesser tumor intraepithelial CD8+ lymphocyte count are poor prognostic indicators for cervical adenocarcinoma patients. COX-2 may play an important role in the suppression of host antitumor immunity in cervical adenocarcinomas.

Adenocarcinoma↗

Mechanisms of cerebral protection by pentobarbital and nizofenone correlated with the course of local cerebral blood flow changes.

The effects of delayed administration of pentobarbital and a novel imidazole derivative (Nizofenone or Y-9179) on the infarction size following the regional cerebral ischemia were studied using the permanent middle cerebral artery (MCA) occlusion model in cats. The courses of local cerebral blood flow (lCBF) before and after drug administration were also studied using the hydrogen clearance method. The extent of infarction one week after MCA occlusion was significantly smaller in the drug-treated groups than in the control group. Regarding the time-course of lCBF, there was no significant differences between the control and the Y-9179 groups. On the other hand, pentobarbital administration caused a significant lCBF increase in low-flow areas where the lCBF following MCA occlusion was below 40 ml/100g/min. In spite of this flow increase, the corresponding cortical areas underwent infarction. Histological examination of the state of vasogenic edema revealed that the perivascular exudation of plasma fluid in the infarcted area was definitely less in the Y-9179 treated group than in the other groups. Results indicate that redistribution of lCBF may not be involved in the mechanism of cerebral protection by pentobarbital or Y-9179.

Animals↗

Sonic detection of intracranial aneurysm and AVM.

This paper describes a method of detecting intracranial aneurysm and arteriovenous malformation (AVM) by analysing weak sounds produced by the blood circulation at the affected part. There is thought to be no turbulence in the normal cerebrovascular system, whereas abnormalities such as aneurysm and AVM sometimes cause turbulence in the blood flow. Thus, a small fraction of the flow energy might be converted into an acoustically detectable noise. For the detection of the sound, sensitive detectors must be applied close to the head since the sound is very weak, and, as in cerebrovascular diseases, the origin of the sound is usually concealed deep inside the hard shelter of the skull. The detection system we used had a gain of 40 to 50 dB greater than that of an ordinary stethoscope. The detection points were the teeth or forehead. Usually the sound started about 160 msec after the ventricular contraction and lasted for 100 to 400 msec. Its frequency component mostly ranged from 400 to 2000 Hz, but the spectrum profile changed according to the position and degree of abnormalities. The uttered sound was very random, which facilitated detection of the position of the sound origin by means of cross correlation methods using a pair of detectors. This method is completely noninvasive, causes no pain to the patient, and might be used even in mass examinations.

Adolescent↗

Ischemic brain edema following occlusion of the middle cerebral artery in the rat. I: The time courses of the brain water, sodium and potassium contents and blood-brain barrier permeability to 125I-albumin.

The present study was undertaken to analyze the roles of brain cations and of the blood-brain barrier (BBB) to albumin in the development of ischemic brain edema. Using the rat middle cerebral artery (MCA) occlusion model, changes in the brain water, sodium, and potassium contents were followed for a period of seven days. The permeability of the BBB to proteins was also followed by 125I-albumin transfer from the blood into the brain. A significant edema developed as early as three hours after MCA occlusion. This progressed rapidly to reach a maximum on the third day, gradually regressing thereafter. The increase in the brain water contents showed a parallel time course to the increase in the sodium and decrease in the potassium contents. A significant increase in the BBB permeability to albumin occurred 72 hours after MCA occlusion. However, there was no correlation between the brain water content and BBB permeability to albumin in the hemispheres studied 72 hours after MCA occlusion. The correlation between the brain water and sodium contents was not clear during the first six hours, but became highly significant thereafter. The data suggest that an increase in the BBB permeability to sodium occurred 12-48 hours after MCA occlusion, which, together with an antecedent intracellular shift of sodium, resulted in a massive influx of water and sodium into the brain. The BBB permeability change to sodium, not to proteins, seems to play a predominant role in the pathogenesis underlying ischemic brain edema.

Animals↗

Ischemic brain edema following occlusion of the middle cerebral artery in the rat. II: Alteration of the eicosanoid synthesis profile of brain microvessels.

Using the rat middle cerebral artery occlusion model, alterations in the eicosanoid synthetic capacity of brain microvessels following ischemia were studied by radiochromatography. Brain microvessels of normal rats predominantly produced hydroxyacids with relatively small amounts of PGD2 and PGE2 from exogenous arachidonic acid. Confirmation that hydroxyacids and prostaglandins were products respectively of lipoxygenase(s) and cyclooxygenase was obtained by experiments using indomethacin and eicosatetraynoic acid. The eicosanoid synthetic capacity of the brain microvessel, especially of hydroxyacids, was significantly enhanced 24 and 72 hours after the onset of ischemia. Because this is the phase of maximum edema in the present model, enhanced eicosanoid production in the brain microvessel may be involved in the mechanisms that underly ischemic brain edema.

Animals↗