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Masayuki Maeda

Publications and source records attributed to Masayuki Maeda.

At least 19 recordsLinked to original sources
PubMed2006

MRI findings of malignant transformation of epidermoid cyst: case report.

Malignant transformation of epidermoid cysts into squamous cell carcinoma (SCC) rarely occurs. A 67-year-old man initially presented with an 8-year history of right trigeminal neuralgia. His symptoms had changed into right facial anesthesia with right-ear hearing impairment 8 months before first consulting a neurosurgeon at our hospital. Results obtained using MRI suggested an epidermoid cyst in the right cerebellopontine angle, but showed atypical findings of a small enhancing nodule in the periphery and surrounding edema in the cerebellum and pons. Surgery was performed to remove the mass, but a small nodule was not reached. Despite stereotactic radiosurgery, the patient's clinical course deteriorated; he died 13 months after the first MRI examination. Autopsy revealed SCC originating from the epidermoid cyst. We present serial MRI and pathologic findings in the early and terminal phases of this patient.

Aged↗
PubMed2006

Diffusion-weighted magnetic resonance imaging in carotid angioplasty and stenting with balloon embolic protection devices.

We compared the results of two procedures to protect against distal embolism caused by embolic debris from carotid angioplasty with stent deployment (CAS) using diffusion-weighted magnetic resonance imaging (MRI). The study group comprised 39 men and 3 women (42 and 3 CAS procedures, respectively) with severe carotid stenosis (average age 70.0 +/- 6.6 years). During 20 CAS procedures the internal carotid artery was protected with a single balloon. A PercuSurge GuardWire was used for temporary occlusion. During 25 CAS procedures the internal and external carotid arteries were simultaneously temporarily occluded with a PercuSurge GuardWire and a Sentry balloon catheter, respectively. Diffusion-weighted MRI was performed 1 to 3 days after CAS. Data from 26 patients undergoing conventional angiography for diagnosis of cerebral ischemic disease, cerebral aneurysm or brain tumors were included as controls. Diffusion-weighted MRI after conventional diagnostic angiography showed ischemic spots in 3 of the 26 controls (11.5%). Ischemic spots were observed during 11 of 20 CAS procedures with the internal carotid artery protected with a single balloon (55.0%), and were observed during 9 of 25 CAS procedures with both the internal and external carotid arteries protected (36.0%). This difference was significant (P = 0.0068). Ischemic lesions appeared not only ipsilateral to the carotid stenosis but also in the contralateral carotid artery (31.9%) and vertebrobasilar territory (25.3%). Better protection was obtained with simultaneous double occlusion of both the internal and external carotid artery than with single protection of the internal carotid artery during CAS.

Aged↗
PubMed2006

Apparent diffusion coefficient in malignant lymphoma and carcinoma involving cavernous sinus evaluated by line scan diffusion-weighted imaging.

PURPOSE: To evaluate the apparent diffusion coefficient (ADC) of malignant lymphomas and carcinomas involving cavernous sinus by line scan diffusion-weighted imaging (LSDWI) and to determine the usefulness of this method for differentiating between the two tumors. MATERIALS AND METHODS: Four patients with malignant lymphomas and six patients with carcinomas were prospectively studied. LSDWI images were obtained with two different b values of 5 seconds/mm(2) and 1000 seconds/mm(2) in the coronal plane. The ADC values of the two types of tumors were calculated and compared. RESULTS: LSDWI provided diagnostic images with minimum susceptibility artifacts and enabled measurement of the ADC. The ADC value (mean +/- SD) was 0.51 +/- 0.06 x 10(-3) mm(2)/second in malignant lymphomas and 0.99 +/- 0.08 x 10(-3) mm(2)/second in carcinomas. A significant difference in ADC values was found between the two (P < 0.01). CONCLUSION: Malignant lymphomas showed significantly lower ADC value than carcinomas. ADC provides additional useful information about differentiation between these tumors.

Adult↗
PubMed2006

Evaluation of a urinary multi-parameter biomarker set for oxidative stress in children, adolescents and young adults.

The involvement of reactive oxygen species (ROS) and oxidative stress in pediatric diseases is an important concern, but oxidative stress status in healthy young subjects and appropriate methods for its measurement remain unclear. This study evaluated a comprehensive set of urinary biomarkers for oxidative stress in healthy children, adolescents and young adults. Results show that urinary excretion of acrolein-lysine, 8-hydroxy-2'-deoxyguanosine (8-OHdG), nitrite/nitrate and pentosidine were highest in the youngest subjects and decreased to constant levels by early adolescence. Urinary acrolein-lysine, 8-OHdG, nitrite/nitrate and pentosidine showed significant inverse correlations with age, but pyrraline did not change significantly with age. No significant differences in biomarkers were apparent between males and females. Younger subjects grow rapidly and sustain immune activation, and are probably exposed to high concentrations of ROS and nitric oxide. Consequently, they are more vulnerable to oxidation of lipids, proteins, DNA and carbohydrates. Normal reported values in this study are a basis for future studies of disease mechanisms involving oxidative stress and for future trials using antioxidant therapies for oxidative stress-related diseases in the pediatric field.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Inhibition of angiogenesis and HIF-1alpha activity by antimycin A1.

We identified antimycin A1 as an inhibitor of the hypoxia-response element (HRE) from screening using a reporter under the control of HRE under hypoxic conditions. Antimycin A1 was effective at 20 pg/ml in inhibiting the reporter activity. The expression of vascular endothelial growth factor (VEGF) mRNA during hypoxia was also inhibited by antimycin A1. Angiogenesis induced by implantation of mouse sarcoma-180 cells was significantly inhibited by non-toxic doses of antimycin A1. Hypoxia inducible factor (HIF)-1alpha protein levels were significantly decreased by antimycin A1, but its mRNA level was not affected. Antimycin A1 is known to be an inhibitor of mitochondrial electron transport system, and depletion of mitochondria abolished antimycin A1-effect, at least in part. Inhibitors of proteasome or protein synthesis did not affect the decrease in HIF-1alpha level induced by antimycin A1. These results indicate that antimycin A1 inhibited angiogenesis through decrease in VEGF production caused by inhibition of HIF-1alpha activation.

Animals↗
PubMed2005

Double-echo perfusion-weighted MR imaging: basic concepts and application in brain tumors for the assessment of tumor blood volume and vascular permeability.

Perfusion-weighted magnetic resonance (MR) imaging using contrast agents plays a key role in characterizing tumors of the brain. We have shown that double-echo perfusion-weighted MR imaging (DEPWI) is potentially useful in assessing brain tumors. Quantitative indices, such as tumor blood volume, are obtained using DEPWI, which allows correction of underestimation of tumor blood volume due to leakage of contrast agents from tumor vessels, in addition to simultaneous acquisition of tumor vessel permeability. This article describes basic concepts of DEPWI and demonstrates clinical applications in brain tumors.

Blood Volume↗
PubMed2005

A case of idiopathic spinal cord herniation with duplicated dura mater.

The patient was a 48-year-old man in whom a slow progression in walking difficulty occurred over a year. Magnetic resonance imaging (MRI) and computed tomography myelography (CTM) revealed duplicated dura mater from T1 to T12 and spinal cord herniation in the inner layer of the dura at the T4-T5 level. Idiopathic spinal cord herniation with duplicated dura mater was diagnosed, and surgery was performed. Intraoperative findings were of an elliptical defect of about 1 cm in the inner layer of the dura at the T4-T5 level, into which the spinal cord was herniated. A 1.5-cm cephalocaudal incision was created in the inner layer of the dura, and the incarcerated spinal cord was released, resulting in resolution of gait disturbance and an excellent postoperative clinical course. We reviewed the reports of 11 cases of idiopathic spinal cord herniation with duplicated dura mater and summarized the clinical and imaging characteristics as follows: 1) A hernial orifice was found at the T4-T6 level, 2) cross-sectional MRI or CTM showed a "snowman-like" deformation of the spinal cord, and 3) symptoms were often improved by widening the hernia orifice.

Dura Mater↗
PubMed2005

Visualization of the intracisternal angioarchitecture at the posterior fossa by use of image fusion.

OBJECTIVE: Magnetic resonance (MR) images most clearly visualize intracranial tissues but have some limitations in terms of detailed analysis of the intracisternal vasculature. To compensate for these shortcomings, an image fusion of three-dimensional digital subtraction angiography (DSA) and MR images, DSA-MR fusion, has been developed. The goal of this study was to evaluate the usefulness of DSA-MR fusion for the visualization of the intracisternal arteries and veins at the posterior fossa. METHODS: Ten consecutive patients (five with neurovascular compression syndrome and five with brain tumors) underwent preoperative DSA-MR fusion. The DSA-MR fusion images were compared with intraoperative findings. RESULTS: Image fusion was performed within 20 minutes, and the registration error was insignificant in all cases. Image fusion successfully visualized the clear three-dimensional relationships among the intracisternal arteries and veins, cranial nerves, brain tissues, and a lesion, and a specific vessel was easily identified. The findings of the DSA-MR fusion images were surgically confirmed in all patients. CONCLUSION: Using this advanced image fusion technique coupled with its reasonable postprocessing time, neurosurgeons may more easily and precisely understand the surgical anatomy before surgery than analyzing three-dimensional DSA and MR images separately.

Adolescent↗
PubMed2005

Different signal intensities between intra- and extracranial components in jugular foramen meningioma: an enigma.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate retrospectively differences in MR signal intensity and contrast enhancement between intra- and extracranial components of jugular foramen meningioma (JFM). METHODS: MR studies of eight patients who underwent surgery for histologically confirmed JFM were reviewed retrospectively. Signal intensity differences between intra- and extracranial components of all eight JFMs on axial T1-, T2-, and postcontrast T1-weighted images were evaluated visually. In six of the eight JFMs, quantitative signal intensity evaluations were also performed by using relative signal intensity ratios of the intra- and extracranial components of JFM to CNS tissue at the same level. Paired t tests were used to evaluate differences in relative signal intensity ratios in each JFM between intra- and extracranial components. RESULTS: Both visual and quantitative signal intensity evaluations revealed that signal intensities of the intracranial component of JFM were significantly higher than those of the extracranial component on T1-, T2-, and postcontrast T1-weighted images. Results of relative signal intensity ratios were 0.89 +/- 0.04 versus 0.77 +/- 0.02 on T1-weighted images (P = .002); 1.66 +/- 0.28 versus 0.88 +/- 0.14 on T2-weighted images (P = .003); and 2.16 +/- 0.29 versus 1.77 +/- 0.26 on postcontrast T1-weighted images (P = .01). CONCLUSION: Intra- and extracranial components of JFM display different signal intensity and enhancement patterns. These differences may be related to histologic composition, and in particular, collagen content.

Adult↗
PubMed2005

Usefulness of the apparent diffusion coefficient in line scan diffusion-weighted imaging for distinguishing between squamous cell carcinomas and malignant lymphomas of the head and neck.

BACKGROUND AND PURPOSE: Squamous cell carcinoma (SCC) and lymphoma are common malignant tumors of the head and neck. The purpose of this study was to determine whether the apparent diffusion coefficient (ADC) in line scan diffusion-weighted imaging (LSDWI) is useful for distinguishing between SCC and lymphoma of the head and neck. METHODS: LSDWI was prospectively performed in 39 patients with SCC and in 14 patients with lymphoma. Images were obtained with a diffusion-weighted factor (b factor) of 5 and 1000 s/mm(2), and ADC maps were generated. ADC values were measured for the two types of tumor. RESULTS: Mean ADC values were 0.96 +/- 0.11 x 10(-3) mm(2)/s for SCC and 0.65 +/- 0.09 x 10(-3) mm(2)/s for lymphoma; the difference was significant (P < .001). All but one of the patients with lymphoma had ADC values lower than the lowest ADC (0.76 x 10(-3) mm(2)/s) in patients with SCC. When an ADC of 0.76 x 10(-3) mm(2)/s was used to distinguish between SCC and lymphoma, accuracy was 98% (52 of 53 lesions). CONCLUSION: ADC values appear to be useful for distinguishing between SCC and lymphoma in the head and neck.

Adolescent↗
PubMed2005

Angioscopic observation during carotid angioplasty with stent placement.

This clinical report is the first to describe angioscopy during carotid angioplasty with stent placement. The average observation time was 3 minutes 43 seconds in 18 cases. The view was clear in 67% of cases. Lesions in the endothelium, rupture of the fibrous cap, clots, debris detaching from plaque, and stent struts were observed. No symptomatic ischemic complications occurred. Diffusion-weighted MR imaging after angioscopy showed asymptomatic ischemic lesions in 47% of cases.

Aged↗
PubMed2004

Effects of antioxidants and nitric oxide on TNF-alpha-induced adhesion molecule expression and NF-kappaB activation in human dermal microvascular endothelial cells.

Cell adhesion molecules expressed on endothelial cells in inflamed skin appear to be controlled by the actions of cytokines and reactive oxygen species. However, molecular mechanisms of the expression of adhesion molecules during skin inflammation are currently not well understood. To evaluate the role of antioxidants and nitric oxide in modulating inflammatory processes in the skin, we examined the effects of pyrrolidine dithiocarbamate (PDTC, 0.1 mM) and spermine NONOate (Sper-NO, 1 mM) on adhesion molecule expression and nuclear factor kappa B (NF-kappaB) activation induced by TNF-alpha (10 ng/ml) in cultured human dermal microvascular endothelial cells (HDMEC). Treatment of cells with TNF-alpha for 4 h significantly induced the surface expression of E-selectin and intercellular adhesion molecule-1 (ICAM-1). Treatment with TNF-alpha for 8 h significantly induced the surface expression of E-selectin, ICAM-1 and vascular cell adhesion molecule-1 (VCAM-1). The up-regulation of these adhesion molecules was suppressed significantly by pretreatment with PDTC or Sper-NO for 1 h. The mRNA expression of E-selectin, ICAM-1 and VCAM-1, and activation of NF-kappaB induced by TNF-alpha for 2 h were significantly decreased by the above two pretreatments. N-acetylcysteine (10 mM) and S-nitroso-N-acetylpenicillamine (1 mM) had no significant inhibitory effects on the cell surface and mRNA expression of these adhesion molecules stimulated by TNF-alpha. These findings indicate that both cell surface and mRNA expression of adhesion molecules in HDMEC induced by TNF-alpha are inhibited significantly by pretreatment with PDTC or Sper-NO, possibly in part through blocking the activation of NF-kappaB. These results suggest a potential therapeutic approach using antioxidant agents or nitric oxide pathway modulators in the treatment of inflammatory skin diseases.

Antioxidants↗
PubMed2004

Oxidative stress in neonates: evaluation using specific biomarkers.

Increased oxidative stress has been implicated in pathogenesis of serious diseases in neonates. We measured urinary levels of 8-hydroxy-2'-deoxyguanosine (a marker of oxidative DNA damage), acrolein-lysine adduct (a marker of lipid peroxidation and oxidative protein damage), and nitrite/nitrate (a marker of endogenous nitric oxide formation) in one-month-old neonates to examine the status of oxidative stress and its relationship to the degree of prematurity and clinical condition in neonates. Study subjects comprised three groups: healthy term neonates, clinically stable preterm neonates requiring no supplemental oxygen, and clinically sick preterm neonates requiring supplemental oxygen and ventilator support. Urinary levels of 8-hydroxy-2'-deoxyguanosine and acrolein-lysine adduct were significantly higher in sick preterm neonates than those of stable preterm and healthy term neonates. In the sick preterm group, neonates developing active retinopathy showed significantly higher levels of acrolein-lysine adduct than the other neonates without retinopathy. There were no significant differences in both urinary markers of oxidative stress between stable preterm and healthy term neonates. The urinary nitrite/nitrate levels were not significantly different among the three groups, suggesting no difference in endogenous nitric oxide formation. Collectively, these results provide evidence of augmentation of oxidative damage to DNA, lipids and proteins, especially in clinically sick preterm neonates.

8-Hydroxy-2'-Deoxyguanosine↗