Search PubMed⌕ Search

Biomedical subjects

K Takakura

Publications and source records attributed to K Takakura.

At least 127 records · Page 7Linked to original sources
PubMed1996

Gamma knife radiosurgery for brain tumors: postirradiation volume changes compared with preradiosurgical growth fractions.

The postradiosurgical volume changes were compared with preradiosurgical growth fractions defined as the tumor doubling time and/or MIB-1 staining index in 14 patients who underwent gamma knife radiosurgery for treatment of various brain tumors. The mean preradiosurgical observation period using neuroimaging techniques was 750 days (range 80-2967 days), and the mean follow-up period after radiosurgery was 664 days (range 328-1100 days). There were four neurinomas, three meningiomas, two craniopharyngiomas, two gliomas, one hemangioblastoma, one pituitary tumor, and one intracranially infiltrative lacrimal gland tumor. The mean patient age at the time of radiosurgery was 52 years (range 8-81 yrs). There were eight males and six females. Following gamma knife radiosurgery, the mean tumor half time was estimated to be 789 days (range 124-2101 days), and the volume reduction against the preradiosurgical tumor volume ranged from 6.3% to 76.1%. This study demonstrates that gamma knife radiosurgery can control tumor growth despite the lack of a correlation with preradiosurgical tumor growth or staining indices for MIB-1. Analyses of this type are essential to show that an "unchanged tumor volume" as demonstrated by postradiosurgery follow-up neuroimaging can be regarded as showing successful radiosurgery.

Adolescent↗
PubMed1996

Bilateral chronic subdural hematomas associated with intracranial hypotension--case report.

A 56-year-old female presented with chronic subdural hematoma due to spontaneous (primary) intracranial hypotension (SIH). She was admitted in a deep coma. Computed tomography showed bilateral chronic subdural hematomas with tight basal cisterns. Percutaneous aspiration of the chronic subdural hematoma with the twist drill revealed negative pressure. The neurological symptoms rapidly improved postoperatively, but the chronic subdural hematoma recurred three times, requiring further aspiration procedures. Patients with SIH may develop subdural hematoma requiring surgical treatment.

Chronic Disease↗
PubMed1996

Adult moyamoya disease progressing from unilateral to bilateral involvement .

A 30-year-old female and a 38-year-old male developed "definite" moyamoya disease after presenting with "probable" moyamoya disease manifesting as ischemic stroke. Angiography at first presentation demonstrated unilateral involvement with normal contralateral findings. The cases were classified as adult type "probable" moyamoya disease according to the diagnostic criteria. Follow-up angiography demonstrated the occlusive lesions had become bilateral, satisfying the criteria for "definite" cases. Serial angiography is required in adults presenting with "probable" moyamoya disease manifesting as ischemic stroke.

Adult↗
PubMed1996

Radiolytic products of bromodeoxyuridine in solids by 60Co gamma-rays and monoenergetic soft x-rays at the K-absorption edge of bromine.

In order to investigate DNA damage due to Auger cascades in bromodeoxyuridine (BrdU), BrdU mixed with other nucleosides, as a model of DNA, was irradiated in solids by gamma-rays and monoenergetic x-rays at around the K-absorption edge of bromine (13.47 keV). The main products of BrdU were deoxyuridine produced through debromination, and bromouracil produced through the decomposition of a sugar group. The rates of the debromination and the nucleobases release of additives were markedly increased in the mixed sample. This observation indicated that the additives surrounding BrdU efficiently supplied protons and then decomposed. The major products by x-rays were the same as those by gamma-rays, indicating that Auger cascades in bromine atoms did not produce specific products. The production rates for all products from the mixed sample were about 2.5 times higher at 13.51 (above the K-absorption edge) keV than at 13.43-keV x-rays.

Bromodeoxyuridine↗
PubMed1996

Double-strand breaks in DNA induced by the K-shell ionization of calcium atoms.

A calcium (Ca)-DNA complex in a buffered aqueous solution was irradiated with monochromatic x-rays at around the K-shell absorption edge of the Ca atom. The energies were 4.030 and 4.071 keV, which correspond to slightly below and above the K-shell absorption edge of Ca (4.047 keV). The number of double-strand breaks (DSB) and single-strand breaks (SSB) per one molecule of Col E1 DNA was calculated using Povirk's equation after the electrophoretic separation of three forms of plasmid DNA (forms I, II and III, which are supercoiled closed circular, open circular and linear, respectively). In a solution with Ca ions, the DSB yield in DNA irradiated with 4.071 keV x-rays is 1.27 times higher than that with 4.030 keV x-rays. In contrast, in the absence of Ca ions, the DSB yield is the same at both the x-ray energies. The SSB yields are also independent of the x-ray energy in the presence and absence of Ca ions. A reference experiment regarding irradiation with 60Co gamma-rays shows that the ratio of the DSB yield to the SSB yield upon irradiation with 4.071 keV x-rays is higher (factor of 3.2) than that with 60Co gamma-rays.

Calcium↗
PubMed1996

[Sedation with flunitarazepam at magnetic resonance imaging in the elderly patients with dementia].

Magnetic resonance imaging (MRI) of the brain is useful in diagnosing senile dementia, but to avoid the creation of artifacts the patient should be kept immobile. We studied the effects of pretreatment with flunitrazepam, a sleep inducer of the benzodiazepine class, as a sedative prior to imaging. The subjects consisted of 108 patients with senile dementia admitted to the Dementia Ward of Kyoto Higashiyama Geriatric Hospital. Their ages ranged from 64-95 years (mean, 81) and the mean body weights of the 76 women and 32 men were 36 and 47 kg, respectively. Immediately before undergoing MRI the patients were given a slow intravenous injection of flunitrazepam (2 mg/ml diluted in 19 ml of saline). Immediately before the patients fell asleep, administration was discontinued and the dose was noted: mean 0.008 mg/kg. In all patients sleep induction and sedation were achieved. No adverse reactions such as apnea were observed. The flunitrazepam dose in our study was much lower than that in previous reports on adults. As body weights of the elderly are also lower than those of younger adults, the optimum dose of flunitrazepam for the elderly may be much lower. Intravenous flunitrazepam may be a useful and safe premedication for MRI in elderly patients with dementia. To avoid serious adverse reactions the dose should be minimized by: 1) determining body weight before MRI, 2) administering diluted flunitrazepam, and 3) discontinuing the drug before the patient falls asleep.

Aged↗
PubMed1996

Effects of a hydroxyl radical scavenger on delayed ischemic neurological deficits following aneurysmal subarachnoid hemorrhage: results of a multicenter, placebo-controlled double-blind trial.

A water-soluble, novel synthetic compound, AVS ((+/-)-N, N'-propylenedinicotinamide; nicaraven) has no demonstrable vasoactive properties but scavenges hydroxyl radicals in aqueous environmental conditions at neutral pH. Based on the results of preceding experimental and clinical studies showing marked ameliorative effects of AVS on cerebral vasospasm and ischemic brain damage, a multicenter, placebo-controlled double-blind clinical trial was undertaken to verify its beneficial effects on delayed ischemic neurological deficits (DINDs) due to vasospasm and on the overall outcome of patients with subarachnoid hemorrhage (SAH). A total of 162 patients with SAH who had Glasgow Coma Scale scores between 7 and 15 on admission were enrolled in the trial. Drug administration (4 g AVS or 4 g glucose as placebo; infused intravenously for 6-8 hours once a day) was begun within 5 days post-SAH and continued for 10 to 14 days. Intent-to-treat analysis of these patients revealed that the overall incidence of DINDs, which was defined as an exacerbation of impaired consciousness and/or focal neurological deficits, was significantly reduced, by 34.5% (placebo 54.2%, AVS 35.5%; p < 0.05, Mann-Whitney U-test). The Glasgow Outcome Scale (GOS) score at 1 month was significantly improved by AVS (p < 0.05, U-test). At 3 months, the difference in the GOS scores between the groups became marginal on U-tests (p < 0.10), but the percentage of good outcome tended to increase, with a relative increase of 20.3% (AVS 76.3%, placebo 63.4%; p < 0.10, chi-square test), and the cumulative incidence of death was significantly reduced (p < 0.05, log-rank test). No significant adverse reaction attributable to treatment was observed. the usefulness of AVS in therapy for SAH is strongly indicated by the fact that the agent significantly ameliorated DINDs, leading to a marked improvement in the GOS scores at 1 month, as well as a reduction in the cumulative incidence of death by 3 months.

Adult↗
PubMed1996

[The relationship between cell proliferation activity and secretory activity in pituitary adenoma--a review of 63 cases].

Determination of the cell proliferation activity of neoplasm is useful in making a prognosis. Immunohistochemical detection using MIB-1 monoclonal antibody has recently allowed us to assess tumor cell proliferation easily, because it can be performed on paraffin-embedded specimens and the results have been demonstrated to be positively correlated with the results of PCNA staining. In this study, surgical specimens of 63 pituitary adenomas were examined by immunohistochemical staining with MIB-1 monoclonal antibody. Twenty-nine cases were non-functioning pituitary adenomas, 20 were prolactin (PRL)-producing pituitary adenomas, and 14 were growth hormone (GH)-producing pituitary adenomas. The MIB-1 positive rates of the pituitary adenomas ranged from 0% to 6.46%. In the non-functioning pituitary adenomas, the MIB-1 positive rates ranged from 0% to 4.55% (mean : 0.76%), in the PRL-producing pituitary adenomas the MIB-1 positive rates ranged 0% to 6.46% (mean : 0.91%), and in the GH-producing pituitary adenomas the MIB-1 positive rates ranged 0% to 1.28% (mean: 0.58%). There were no significant differences between these values according to the results of the Wilcoxon signed-rank test. Although the size of the non-functioning pituitary adenomas was not correlated with their MIB-1 positive rate, tumor size was closely correlated with the interval between the onset of the initial symptoms and the date of surgery. In the PRL-producing pituitary adenomas, the MIB-1 positive rate was not correlated with serum PRL levels as an index of secretory activity, but was correlated with the PRL staining positive rate. Preoperative bromocriptine therapy proved effective in reducing tumor size and serum PRL levels, but had no effect on the MIB-1 positive rate. In the GH-producing pituitary adenomas, the MIB-1 positive rate was not correlated with serum GH levels as an index of secretory activity, but was closely correlated with the GH staining positive rate. All three groups included both invasive and noninvasive tumor types, but there were no close statistical correlations between the three tumor types.

Adenoma↗
PubMed1996

[Lessons from experience of bertrand's selective peripheral denervation for splenius type torticollis].

A 23-year-old male with splenius type torticollis underwent selective denervation of C1 and C2 roots and C3-C6 spinal posterior rami, with excellent results. Based on this experience, we stress the importance of dynamic EMG and thorough review of video recording for identifying the involved neck muscles. In the operative procedures, the nerve rami are identified under the semispinalis muscle. To dissect the correct plane under the semispinalis muscle, the key point to keep in mind is to follow the great occipital nerve to the proximal part. An ultrasonic blood flow meter is useful to locate the vertebral artery in the spaces between the occiput and the C1 lamina and between C1-C2 laminae. Because fine nerve branches run in the soft tissues over the laminae, to avoid transient neuroapraxia, dissection around the C1, C2 arches should not be carried out under the periosteum, as is usually done in case of laminectomy. Dissection of C1 and C2 rami as far as the very medial part is rather difficult because of bleeding from the venous plexus and the presence of the vertebral artery. Therefore, the intradural approach might be easier for sectioning the C1 and C2 roots. We would like to add these points to the original description by Bertrand.

Adult↗
PubMed1996

[A clinico-pathological study of cystic spinal Schwannomas].

It is not rare for a spinal Schwannoma to have cystic formations, but there are various opinions about the mechanism. Since the installation of MRI in our institution in 1989, we have experienced 4 cases of cystic spinal Schwannoma. The diagnosis of such lesions was based on identifying cystic formations histopathologically. Among these cases, tiny hemorrhages were noted microscopically in three of them along with hemosiderin depositions and phagocytes containing hemosiderin. Besides, there are also a lot of sinusoidal vessels with thin endothelium. Perhaps in these three cases, it is the tiny hemorrhages that resulted in degenerative changes which in turn caused the formation of microcysts. But in addition to the above findings, a lot of hyalinized vessels were also demonstrated in the angiomatous components of two cases. Therefore, it is also possible that the microcyst formation is secondary to the degenerative changes caused by ischemia within the tumors. On the other hand, in the only case without hemorrhage, neither phagocytes containing hemosiderin nor abnormal sinusoidal vessels could be found. In stead, a lot of clear foamy cells with positive lipid staining were seen. There may be some factors underlying the xanthomatous change of these tumors that cause their vacuolar formation from degenerated of the foamy cells. It is possible that all three factors mentioned above may act alone or in combination to contribute to the formation of cysts. At its late stage, a spinal Schwannoma may have various findings which can not be classified into either Antoni A or Antoni B type. In conclusion, a spinal Schwannoma can occasionally have cystic formations. Its mechanisms can be a hemorrhagic or an ischemic process occurring within the tumor.

Adult↗
PubMed1996

A clinico-immunohistochemical study of giant cell glioblastoma.

We have reported 7 cases of giant cell glioblastoma. All cases died within 14 months despite aggressive treatment. By immunohistochemical staining, lymphocyte infiltration was found in 6 cases. GFAP and vimentin stained positive in all cases. The MIB-1 positive rate was 13.8-90% (average, 34.9%); small and mononucleated giant cells stained more than multinucleated and monstrous cells. It was concluded that this tumor can be highly malignant and its degree of malignancy is determined by the biological behavior of the mononucleated giant cells and small cells.

Adult↗
PubMed1996

Pleomorphic xanthoastrocytoma with neurofibromatosis type 1: case report.

The authors report a case of pleomorphic xanthoastrocytoma (PXA) with neurofibromatosis type 1 (NF-1). A 21-year-old woman, noted to have had a number of café au lait spots since birth, presented with the chief complaint of headache. Neuroradiological studies revealed a cystic tumor of the left parietal lobe. Surgical treatment was performed. The tumor was located on the surface of the parietal lobe with the formation of cysts. Light, electron microscopic, and immunohistochemical examination showed the characteristics of typical PXA. This is the second reported case of NF-1 associated with PXA.

Adult↗
PubMed1996

Correlation between MR image characteristics and histological features of acoustic schwannoma.

We retrospectively studied 21 cases of histologically proven acoustic shwannomas with an emphasis on the correlation of their magnetic resonance imaging (MRI) findings and histological features. All cases were of low signal intensity in the T1W MRI. In the T2W MRI, 9 of them were of homogeneous high signal intensity (Hom-HSI-T2) and 12 of them were of heterogeneous high signal intensity (Het-HSI-T2). The cases of Hom-HSI-T2 were generally associated with capsular enhancement, and were usually cystic tumors with high vascularities and mainly Antoni A tissues. On the contrary, the cases of Het-HSI-T2 were generally associated with homogeneous enhancement, and were usually solid tumors with low vascularities and various tissue components.

Adult↗
PubMed1995

Development of an MRI-compatible needle insertion manipulator for stereotactic neurosurgery.

A variety of medical robots for stereotactic neurosurgery has been developed in recent years. Almost of all these robots use computed tomography (CT) to scan the brain of the patient before and during surgery. Currently, we are developing a needle insertion manipulator for magnetic resonance imaging (MRI)-guided neurosurgery. MRI techniques, including MRI angiography and functional MRI, are attractive for the development of interventional MRI therapies and operations. If a robot were available, these therapies would be minimally invasive, with more accurate guidance than is possible with current CT-guided systems. Actuation of a robot in an MRI environment is difficult because of the presence of strong magnetic fields. Therefore, the robot must be constructed of nonmagnetic materials. The system frame was manufactured using polyethylene terephthalate (PET) and was actuated using ultrasonic motors. Accuracy-evaluation procedures and phantom tests have been performed. The total accuracy of the system was approximately 3.0 mm. No artifacts caused by the manipulator were observed in the images.

Brain↗
PubMed1995

A new approach to the control of central deafferentation pain--spinal intrathecal baclofen.

We investigated the short-term effects of an intrathecal bolus injection of baclofen on central pain due to stroke or spinal cord injury. Pain relief was obtained in 64% of the patients. The effects developed 1-2 hours after the injection and continued for 10-24 hours. Both spinal segmental and supraspinal mechanisms may be involved in the production of baclofen-analgesia.

Afferent Pathways↗
PubMed1995

Chronic expanding epidural haematoma. Case report.

An encapsulated fluid epidural haematoma in a 9-year-old boy was successfully evacuated by a simple burr hole procedure 5 months after a minor head injury. Clinicopathological findings suggested that chronic expansion of an initially unsuspected epidural haematoma occurred as a result of repeated haemorrhages from the haematoma membrane, resulting in an unusually long delayed appearance of clinical evidence. This case demonstrates that a chronic expanding process similar to that seen in chronic subdural haematoma needs to be considered as a possible complication of epidural haematoma and indicates an important role for the haematoma membrane in the chronic expansion of epidural haematoma.

Child↗