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Biomedical subjects

Y Horikawa

Publications and source records attributed to Y Horikawa.

198 records · Page 11Linked to original sources
PubMed1979

[Medulloblastoma with extracranial metastases--a case report (author's transl)].

A case of medulloblastoma with extracranial metastases was reported. A 20-year-old woman was operated on for cerebellar medulloblastoma twice during the past 5 years and a half. Two years after the second operation, she revealed the metastases to the cervical, axillar and inguinal lymphnodes, and to the skeletal system, such as the skull, scapula, humerus, sternum, spine, pelvis and femur. The cause of extracranial metastases in the very core in this case. While the tumor was located deep in the cerebellar hemisphere at the first operation, it spread over the cerebellar surface at the after the second operation, so that the tumor cells became infiltrative to the dura mater. Thus through lymphatic and circulatory system extracranial metastases occurred. The location of the tumor seems important in this case.

Adult↗
PubMed1978

[A case of binasal quadrantanopsia due to opto-chiasmal arachnoiditis (author's transl)].

A case of binasal quadrantanopsia due to chiasmal arachnoiditis was reported. The patient was a 28-year-old man who complained of blurring of vision for 12 months. Visual acuity of the right eye was 20 cm/numerus digitorum and the left 0.7X contact lens. Visual field revealed binasal lower quadrantanopsia. Pneumoencephalogram showed poor filling in the chiasmatic cistern, but the angiogram and CT scan showed no parasellar mass lesion. Then optochiasmal arachnoiditis was diagnosed and a right frontal craniotomy was performed. The arachnoid around the post-fixed chiasm was thickened and adhered to the bilateral rectal gyri. Proximal parts of A--1 segments of bilateral anterior cerebral arteries were displaced medially and downward, compressing the both lateral aspects of the chiasm. Compression of the optic chiasm by the anterior cerebral arteries was relieved after removed of the arachnoid. Despite of the slight improvement of visual acuity, visual fields were not changed postoperatively. The authors briefly discussed the mechanism of binasal hemianopsia in our case and reviewed recent literatures.

Adult↗
PubMedDate not supplied

Discrimination between different types of white matter edema with diffusion-weighted MR imaging.

Brain edema can be classified into three categories: vasogenic, cytotoxic, and interstitial. The mechanism of edema is thought to be different in each type. The authors studied the movement of water molecules in each type of white matter edema in a rat model by using diffusion-weighted magnetic resonance imaging. Conventional T2-weighted imaging did not allow distinction between the three types of white matter edema; the three types of edema were, however, distinguished by using diffusion-weighted imaging. The apparent diffusion coefficient (ADC) of water was different in each type of edema. Water molecules in cytotoxic edema induced by triethyl-tin intoxication showed a smaller and less anisotropic ADC than in normal white matter. In contrast, water in vasogenic edema induced by cold injury had a larger and more anisotropic ADC than in normal white matter. Water in interstitial edema due to kaolin-induced hydrocephalus had an anisotropic and very large ADC.

Animals↗
PubMedDate not supplied

MR angiography of intracranial aneurysms: a comparison of 0.5 T and 1.5 T.

The objective of this paper is to compare the diagnostic efficacy of 3 DFT time-of-flight MR angiography (MRA) at middle-field-strength and high-field-strength in diagnosis of intracranial aneurysms. Thirty-one patients, including 26 patients with angiographically confirmed intracranial aneurysms (n = 28), underwent MRA at 0.5 and 1.5 T. Images were interpreted by six trained observers who were blinded to diagnosis. Twelve projections of MRA of the circle of Willis, by maximum-intensity projection algorithm, were reviewed using continuous confidence-judgement scales. It was found that MRA at 1.5 T was more sensitive than that at 0.5 T in detection of aneurysms. The sensitivity of six observers ranged between 50 and 64% (mean 56%) at 0.5 T, and between 61 and 86 86% (mean 75%) at 1.5 T. In the smaller aneurysms less than 5 mm, the differences between the units became greater. The sensitivity for small aneurysms ranged from 23 to 54% (mean 32%) at 0.5 T, and from 31 to 69% (mean 58%) at 1.5 T. Our conclusion was that high field strength confers higher accuracy in the detection of intracranial aneurysms with MRA with current-generation MR imagers.

Algorithms↗
PubMedDate not supplied

Imaging of optical disc using reflection-mode scattering-type scanning near-field optical microscopy.

A phase-change optical disc was observed using a reflection-mode scattering-type scanning near-field optical microscope (RS-SNOM). In an a.c.-mode SNOM image, the 1.2 microm x 0.6 microm recording marks were successfully observed although the data were recorded on the groove. In contrast, no recording marks could be resolved in a d.c.-mode SNOM image. These results are in good agreement with those from a numerical simulation using the finite difference time domain method. The resolution was better than 100 nm with a.c.-mode SNOM operation and the results indicate that recording marks in phase-change optical media can be directly observed with the RS-SNOM.

Journal Article↗
PubMedDate not supplied

Proton NMR relaxation times in ischemic brain edema.

The state of water in cerebral ischemia was studied by using the proton nuclear magnetic resonance (1H-NMR) method. Cerebral ischemia was induced experimentally in Mongolian gerbils by unilateral ligation of the common carotid artery. Longitudinal (T1) and transverse (T2) relaxation times of the ischemic brain were measured with a pulse FT-NMR spectrometer and the water content was determined by the wet/dry method. Quantitative analysis of the relaxation times was performed sequentially during the initial 7 hours following ligation and the data were compared with those of brain edema previously reported by S. Naruse in the rat. Characteristic findings in brain ischemia include prolongation of the slow component of T2 and increase in the water content. A quantitative comparison of relaxation rate and water content demonstrates that ischemic brain edema in Mongolian gerbils is different from cytotoxic and vasogenic types of brain edema. When R2 (1/T2) was plotted against the water content, the slope value of ischemia in the gerbil was between the slope values of the TET intoxication and cold injury induced edemas reported previously. From these results, it might be said that ischemic brain edema includes both the cytotoxic and vasogenic types of brain edema. Glycerol was demonstrated to affect brain ischemia by decreasing the water content and by shortening the slow component of T2. By analysis of the relaxation times and water content, we examined the pathophysiological characteristics of water molecules in ischemic brain tissue.

Animals↗
PubMedDate not supplied

Diffuse glomerulosclerosis without tubular injury does not directly manifest renal dysfunction in nephrotic mice (ICGN strain).

Chronic renal disease is characterized by pathological conditions, caused by a progressive and irreversible loss of renal function. The nephrotic mouse (ICGN strain) is a useful model for demonstrating progressive nephrotic syndrome (NS). In the present study, we examined the natural course of kidney disease shown by the NS mice, aging 6-26 weeks, in order to characterize their pathological conditions. Urine and serum biochemistry revealed that massive albuminuria and hypoalbuminemia were evident in the NS mice throughout the observation period and that blood urea nitrogen (BUN) and serum creatinine levels began to increase from 14 weeks after birth. Renal histopathology demonstrated that glomerulosclerotic lesion was diffusely observed in the renal cortical area from 6 weeks after birth. Furthermore, the tubular lesions, characterized by tubular cellular atrophy and luminal cast formation, became mild to moderate and severe in the 14- and 26-week-old NS mice, respectively. Although the 6- and 10-week-old NS mice exhibited diffuse mesangial expansion, BUN and serum creatinine levels were normal as long as the tubular architecture remained almost intact. There was a good correlation between BUN level and tubular injury index (r2 = 0.860, p < 0.001), while no significant relationship was seen between the BUN level and glomerular matrix index. Our model, an experimental analogue of human chronic renal disease, clearly demonstrates that glomerulosclerosis is not always a direct determinant for renal dysfunction.

Actins↗