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Y Sawamura

Publications and source records attributed to Y Sawamura.

At least 37 records · Page 2Linked to original sources
PubMed2001

p73 is not mutated in meningiomas as determined with a functional yeast assay but p73 expression increases with tumor grade.

The p53 gene is normally wild type in meningiomas. Since all three members of the p53 gene family recognize the same DNA sequence, tumors containing wild type p53 could decrease transactivation of p53 target genes by mutating either p63 or p73. In meningiomas the most likely target is p73, because loss of heterozygosity of the chromosomal band containing p73 is the commonest genetic lesion in these tumors. To screen p73 for mutations we have developed a functional assay which tests the ability of p73 to activate transcription from a p53-responsive promoter in yeast. The assay correctly identified p73 mutants with mutations equivalent to hotspot mutations in p53, demonstrating that the assay can detect transcriptionally inactive p73. No mutations in p73 were identified in meningiomas. p73 RNA level was higher in more advanced tumors, but there was no correlation between the expression level of p73 and p21, a known p53 target gene. The yeast assay was also used to measure the intrinsic sensitivity of the p73 protein to mutagenesis. Like p53, p73 is exceptionally easy to inactivate as a transcription factor by point mutation. Taken together, these results indicate that p53 and p73 serve very different functions in tumors.

Aged↗
PubMed2001

[Minimally invasive stereotactic functional surgery using an intravenous anesthetic propofol and applying Image Fusion and AtlasPlan].

Image-guided stereotactic surgery of the ventralis intermedius nucleus of the thalamus, globus pallidus, and subthalamic nucleus is a prevailing modality as a treatment of movement disorders. This technical note describes a method of minimally-invasive stereotactic functional surgery for patients with parkinsonian symptom or various tremors. Patients were administered propofol, an intravenous anesthetic, during placement of a burr hole and a stereotactic frame, but not the period when the patients were necessary to be awake. The intravenous anesthesia was very beneficial to relieve local pain and mental stress of the patients. Radionics ImageFusion and AtlasPlan were used for defining the target localization without an intraoperative ventriculography. ImageFusion efficiently fused high-resolution MR images on CT images. AtlasPlan accurately corrected the localization of the tentative target point after measurements from the midpoint of the anterior commissure-posterior commissure line on the modified MRI, and enabled us to reduce the degree of an intraoperative correction to fix a final target. Stereotactic functional surgery has been thought to be less-invasive, however further modifications of surgical procedure and intraoperative medication can make this type of surgery much more less-invasive.

Anesthesia, Intravenous↗
PubMed2001

MR imaging of the brain in lymphomatoid granulomatosis.

BACKGROUND AND PURPOSE: Clinical diagnosis of lymphomatoid granulomatosis (LG) of the brain, in patients without skin or chest lesions, usually is difficult because of the nonspecific neurologic manifestations, laboratory data, and CT appearance. Our aim was to characterize the MR appearance of LG of the brain. METHODS: We retrospectively reviewed the MR images in four patients (35 to 72 years old) with histologically confirmed LG of the brain. RESULTS: On T2-weighted images, we noted diffuse hyperintense lesions in the cerebral white matter bilaterally (n = 3), in the brain stem and cerebellar hemisphere (n = 1), and patchy hyperintense lesions the brain stem (n = 2). On contrast-enhanced T1-weighted images, we observed multiple punctate or linear enhancements residing along the perivascular space (n = 4), nodular enhancements (n = 2), ringlike enhancements (n = 1), and a large, enhanced mass (n = 1). All patients had multifocal lesions. CONCLUSION: Although the MR appearance of LG of the brain varies, multiple punctate or linear enhancements that reside along the perivascular space suggest LG.

Adult↗
PubMed2000

Fractionated stereotactic radiotherapy for vestibular schwannoma (VS): comparison between cystic-type and solid-type VS.

PURPOSE: To compare the effectiveness and complications of fractionated stereotactic radiotherapy (SRT) for cystic-type vestibular schwannoma (VS) with those of solid-type VS. METHODS AND MATERIALS: In 65 patients treated with fractionated SRT between 1991 and 1999, 20 were diagnosed with cystic VS, in which at least one-third of the tumor volume was a cystic component on magnetic resonance imaging (MRI), and 45 were diagnosed with solid VS. Thirty-six Gy to 50 Gy in 20-25 fractions was administered to the isocenter and approximately 80% of the periphery of the tumor. All cystic and solid components were included in the gross tumor volume. The mean follow-up period was 37 months, ranging from 6 to 97 months. RESULTS: The actuarial 3-year rate of no episode of enlargement greater than 2.0 mm was 55% for cystic-type and 75% for solid-type VS; the difference was statistically significant (p = 0.023). The actuarial 3-year tumor-reduction (reduction in tumor size greater than 2.0 mm) rates were 93% and 31%, respectively (p = 0.0006). The overall actuarial tumor control rate (no tumor growth greater than 2. 0 mm after 2 years or no requirement of salvage surgery) was 92% at 5 years in 44 patients with a follow-up period of 2 or more years. There was no difference in the class hearing preservation rate between cystic VS and solid VS. No permanent trigeminal or facial nerve palsy was observed in either group. CONCLUSION: Transient tumor enlargement occurs in cystic VS more frequently than in solid-type VS, but the subsequent tumor-reduction rate in cystic VS is better.

Actuarial Analysis↗
PubMed2000

Deep brain stimulation of subthalamic area for severe proximal tremor.

Proximal tremors are often refractory to nucleus ventrointermedius thalami thalamotomy. Subthalamotomy has been suggested to be effective for treatment of tremor, although this procedure is associated with considerable adverse effects, and has rarely been considered a suitable treatment modality. The authors demonstrate the efficacy and safety of subthalamic deep brain stimulation in two patients, one with a severe, refractory proximal essential tremor and one with tremor with dystonia.

Aged↗
PubMed2000

Application of advances in molecular biology to the treatment of brain tumors.

Recent advances in molecular biology have substantially improved our understanding of the molecular genetics of primary brain neoplasms. Soon each histopathologic category of glioma will be further divided into subgroups according to similar genetic background, gene expression profile, and similarity of biologic responses to radiotherapy or chemotherapy. Identification of key molecules that are specifically altered in neoplastic cells will provide candidate molecular targets for tumor treatment. Novel therapeutic tools for targeting tumor cells, such as viral vectors for gene therapy, have been created. In the near future, the accumulation of new knowledge in brain tumor biology and genetics, combined with rational drug design, will revolutionize the treatment of malignant gliomas, which are among the most lethal human cancers.

Apoptosis↗
PubMed2000

Phase II trial of pre-irradiation KRN8602 (MX2) in malignant glioma patients.

KRN8602 (MX2) is a newly developed morpholino anthracycline that crosses the blood-brain barrier where it becomes distributed in brain tissue after intravenous administration. This morpholino anthracycline has been found to be effective against human glioma cells and the intracerebrally transplanted tumors in vivo, We performed a phase II trial using KRN8602 as a single agent in malignant glioma patients who had not received prior adjuvant therapy. The 13 patients (5 glioblastomas, 7 anaplastic astrocytomas and 1 malignant oligodendroglioma) enrolled received at least 1 cycle of KRN8602 at 35 mg/m2/day in 3-4 week intervals by intravenous bolus. Ten of these patients could be evaluated for response, and 13 for toxicity. Three patients (1 glioblastoma and 2 anaplastic astrocytomas) demonstrated a complete response (3/10, 30%). Concerning side effects, myelosuppression was moderately severe, with 30.7% of patients developing grade 3 leukopenia. Severe nausea/vomiting was observed in 69% of the patients, however, cardiotoxicity was not observed. The results indicate that KRN8602 demonstrated modest activity against malignant glioma with relatively severe, but manageable toxicity. Further assessment of the efficacy and toxicity of KRN8602 against malignant glioma may be worthwhile.

Adult↗
PubMed2000

Asymptomatic schwannoma of the oculomotor nerve: case report.

Intracranial oculomotor schwannoma without neurofibromatosis is rare and is usually symptomatic. Only one case of asymptomatic oculomotor schwannoma has been previously reported. We present a case of intracranial oculomotor schwannoma which caused no signs or symptoms. Microsurgical resection of this tumour resulted in oculomotor palsy. We reviewed 7 reported cases and the findings indicated that radical removal of the tumour invariably caused or worsened the oculomotor palsy. The reason why the tumour caused no symptoms in this case was unclear. However, improvements in diagnostic methods such as magnetic resonance imaging (MRI) may increase the detection of such asymptomatic cases. Indications for surgical treatment should be established.

Aged↗
PubMed2000

Minimally invasive surgical exposure of the extreme high cervical internal carotid artery: anatomical study.

The purpose of this study is to investigate a minimally invasive access to a high cervical lesion involving the internal carotid artery. Using 13 fixed cadaveric preparations, we sought to design a surgical approach that would cause minimal involvement of the surrounding structures and maximal exposure to the extreme high cervical area. This technique preserves the function and integrity of the mandible, sternocleidomastoid, posterior belly of digastric and styloid process muscles. The method uses retraction and mobilisation of those muscles, as well as decompression of the facial from the stylomastoid foramen. The internal carotid artery is exposed up to the entry point into the carotid canal. The cranial nerves IX, X, XI and XII are kept in sight up to the jugular foramen. This approach creates a wide corridor into the deep high cervical and inferior cranial base area and can be utilised for high cervical carotid lesions and tumours related to the artery.

Aged↗
PubMed2000

Experience with 24 cases of reconstructive anterior skull base surgery: classification and evaluation of postoperative facial appearance.

This article details our experience with 24 cases of anterior skull base reconstruction after tumor resection. They were classified into four types according to the resected region. In 11 cases of type I resection, the orbital part of frontal bone and/or cribriform plate of ethmoid bone were resected. In two cases of type II resection, the orbital contents and partial orbital bone were resected with the addition of type I. In five cases of type III resection, the maxillary bone was resected with the addition of type II. In six cases of type IV resection, the zygomatic bone and/or facial skin were resected with the addition of type III. The tumor originating from intracranial region was 25% of this series and all of them belonged to type I. The tumor originating from extracranial region tumor was 75% and its resected region was more extensive. In type I and II resections, the cranial flap, radial forearm free flap, or a combination of the two was used for reconstruction. The rectus abdominis myocutaneous/muscle free flap was used for reconstruction of massive defects in type III and IV defects. Total incidence of postoperative complications was 16.7%. Donor site deformity of the cranial flap at the frontal and temporal region in types I and II resections and facial contour deformity in zygomatic region and defect of upper and/or lower palpebra in type IV resection were major problems with postoperative facial appearance. Although use of the rectus abdominis myocutaneous free flap combined with costal cartilages improved the midfacial contour, palpebral reconstruction remained an unsolved problem in reconstructive skull base surgery. The reconstructive goals in skull base surgery are not only to obtain safe and reliable skull base reconstruction but also to restore the facial appearance postoperatively.

Journal Article↗
PubMed2000

Spinal intramedullary ependymomas: surgical results and immunohistochemical analysis of tumour proliferation activity.

This study analysed the outcome of 35 consecutive patients with intramedullary ependymoma who underwent a radical surgical resection between 1983 and 1996. The median age of patients was 47 years. Tumour location was cervical in 22 patients, cerviothoracic in eight and thoraco lumber in five. The proliferative activity of 24 spinal and 14 intracranial ependymomas were determined by MIB-1 immunolabelling. Total removal of tumour was achieved in 26 patients and subtotal removal was performed in nine patients of whom six received postsurgical radiation therapy. Twenty-nine patients out of 35 could be followed over 3 years (follow-up periods: 168-36 months: mean 70). Moreover many patients could be followed over 4 years. In 27 of those 29 patients, the neurological symptom was stabilized or improved. The proliferation indices of spinal ependymomas were significantly lower than those of intracranial ependymomas. Tumour regrowth occurred only in a young patient 29 months after a subtotal removal of the tumour which was not treated with irradiation and showed a high proliferation index on the second operation.

Adolescent↗
PubMed2000

Topography of the vestibulocochlear nerve.

OBJECTIVE: The terms superior vestibular nerve and inferior vestibular nerve have been used in the field of neurosurgery to indicate anatomically the two respective vestibular components of the vestibulocochlear nerve. To reappraise the aptness of this terminology, fascicular patterns and the anatomic relationship of the vestibular and cochlear components were examined. METHODS: Twenty vestibulocochlear nerve specimens were obtained from cadavers. The nerves were excised, with care taken to sustain their spatial relationships, then embedded in paraffin blocks and cross sectioned in 10-microm-thick slices. Serial cross sections were stained and examined with a light microscope. RESULTS: The vestibular component was separated into two parts only at the lateral fundus of the internal auditory canal, lateral to the vestibular ganglion. In the internal auditory canal of all specimens, the vestibular component was represented by numerous fascicles. Around the porus acusticus, the fascicular pattern among the specimens was diverse: 13 of the 20 specimens were still polyfascicular, 4 specimens consisted of two large, distinct fascicles, and, in the remaining 3 specimens, a portion of the vestibular fascicles had fused with the cochlear component. Near the root entry zone, all vestibular fascicles fused and merged with the cochlear nerve to form a single trunk. CONCLUSION: There was no evidence to support the anatomic correctness of specifying the superior and inferior vestibular nerves, except in the lateral fundus of the internal auditory canal.

Brain Stem↗
PubMed2000

Surgical approaches for the treatment of aneurysms on the P2 segment of the posterior cerebral artery.

OBJECTIVE: The P2 segment of the posterior cerebral artery has remained a challenging region to expose surgically. We establish a surgical strategy for P2-segment aneurysms. METHODS: Each segment of the posterior cerebral artery was classified according to Zeal and Rhoton's classification. Fourteen of 18 P2-segment aneurysms were surgically treated. The patient's outcome, the aneurysm location, and the surgical procedures were evaluated. A cadaveric study was performed to clarify the surgical view obtained via three different surgical approaches. RESULTS: Nine aneurysms were clipped, two were trapped, one was coated, and one was excised with parent artery reconstruction. Cerebral revascularization techniques were used for three patients. The pterional approach exposed the anterior half of the P2a segment. The subtemporal approach revealed the P2a segment, but its exposure was restricted by its localization in the ambient cistern. Via the occipital interhemispheric transtentorial approach, the P2p segment was visible and could be manipulated. When the posterior half of P2a segment was high on a coronal view of magnetic resonance imaging, it was extremely hard to access via any approach. CONCLUSION: A surgical strategy for the P2 aneurysm can be planned with accurate prediction of the aneurysm location. When the localization of an aneurysm on the posterior half of P2a segment is high, a resection of brain tissue may be required.

Adolescent↗
PubMed2000

Dependence of efficient adenoviral gene delivery in malignant glioma cells on the expression levels of the Coxsackievirus and adenovirus receptor.

OBJECT: Recombinant adenovirus is used as a competent vector in a wide spectrum of cancer gene therapies because of its high efficiency in gene delivery. To study the feasibility of gene therapy in malignant gliomas, the authors examined the antiproliferative effect of the adenovirally transduced wild-type p53 tumor suppressor gene by using 15 different high-grade glioma cell lines. METHODS: Although growth suppression in association with a high adenoviral p53 transduction efficiency was seen in five of 15 cell lines, it was not observed in the remaining 10 cell lines. To clarify the underlying mechanism, we examined the expression levels of the Coxsackievirus and adenovirus receptor (CAR), which is the primary receptor for adenovirus, and of the integrins alpha vbeta3 and alpha vbeta5, which promote adenoviral internalization. The expression level of the CAR gene showed a close correlation to adenoviral gene transduction efficiency in the tested cell lines, whereas the expression levels of the integrins did not. The CAR expression was decreased by wild-type p53 transduction in U251MG cells harboring mutant p53 and increased by antisense inhibition of p53 in LN443 cells with endogenous wild-type p53. CONCLUSIONS: The results of this study indicate that CAR expression is a critical determinant of transduction efficiencies in adenovirus-based gene therapy for human malignant gliomas.

Adenoviridae↗
PubMed2000

[Two cases of the epidermoid on the petrous bone].

Epidermoids known as cholesteatomas, are congenital benign tumors and originate in the embryonic ectoderm. They account for 1.3% of all intracranial tumors. They are often found in the cerebellopontine angle and the paraseller region, but rarely in the petrous portion of the temporal bone. Epidermoids of the petrous bone tend to slowly present progressive facial palsy and hearing disturbance. In this article, two cases of epidermoids involving the petrous bone are reported. A 55-year-old male presented left facial palsy, left hearing disturbance and decreased gustation in the left side of the tongue. MRI revealed a non-enhanced mass on the petrous portion of the left temporal bone, and bone-window CT showed bone destruction in the same region (Case 1). A 71-year-old female was aware of left facial palsy and left hearing loss for 15 years. MRI showed a non-enhanced mass on the petrous bone, and bone-window CT demonstrated extensive bone erosion of the petrous bone and the middle cranial fossa (Case 2). In both cases, total removal was performed via the middle cranial fossa approach. Both tumors existed extradurally and had pressed against the genicurate ganglion of the facial nerve. The facial palsy of the former case recovered 12 months after surgery. We discuss the problems of diagnosis and treatment of epidermoids of the petrous bone.

Aged↗
PubMed2000

[Germinoma].

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Adolescent↗