Search PubMed⌕ Search

Biomedical subjects

Y Yoshii

Publications and source records attributed to Y Yoshii.

At least 55 records · Page 3Linked to original sources
PubMed1996

[FLAIR images of patients with head injuries].

FLAIR (fluid-attenuated inversion recovery) images are MR images obtained with an inversion recovery sequence, which has a long inversion time (TI) and a long echo time (TE). We examined 29 cases (49 graphics) of cerebral contusion, 11 cases (22 graphics) of diffuse axonal injury (DAI) and 11 cases (11 graphics) of traumatic subarachnoid hemorrhage (t-SAH) with FLAIR sequence consisting of a repetitive time (TR) of 6500 msec, TI of 1700 msec and TE of 110 msec, and these graphics were compared with T2-weighted images by spin-echo sequence (TR 2500 msec, TE 90 msec) and computed tomographic (CT) scans. Some lesions of DAI were demonstrated more clearly with FLAIR images than with conventional T2-weighted images. Although contusion could be detected with FLAIR images as well as with conventional T2-weighted images, lesions adjacent to cerebral sulci were better delineated with FLAIR images. Because the cerebrospinal fluid signals in cerebral sulci were low-intensity, FLAIR images were useful in detecting lesions of the cerebral cortex adjacent to cerebral sulci. Although it has been reported that detection of SAH is difficult with standard T1- and T2-weighted images, the presence of t-SAH could be confirmed with FLAIR images as seen in CT scans.

Adult↗
PubMed1996

Correlation of histopathological factor of brain tumor and high thallium-201 uptake in single photon emission computed tomography.

This study was undertaken to investigate the relationship between several histological features and the degree of TI-201 uptake in brain tumors. T1-201 SPECT was performed on 52 patients with intracranial lesions. Histological examinations were carried out to determine the gradation of tumor cell density, vascularization, small-cell density, and matrix loosening, and the presence of necrosis, atypia, mitoses, and endothelial proliferation. The histological findings were classified into three categories. While the early uptake of T1-201 depended on the degree of necrosis of glial tumor, the delayed T1-201 uptake was closely related to the degree of necrosis, tumor cell density, and small-cell density, and may thus be of value for estimating the viability and degree of malignancy of glial tumors. In the non-glial tumors, the early and delayed T1-201 uptakes were closely related to all histological parameters, with the increase of necrosis and vascularization in the tumor tissue being particularly closely related to high uptake levels.

Astrocytoma↗
PubMed1996

[FLAIR images of cerebral and brain stem infarction].

FLAIR (fluid-attenuated inversion recovery) images are MR images obtained with an inversion recovery sequence having a long inversion time (TI) and a long echo time (TE). We examined 47 cases (56 graphics) of lacunar infarction (LI), 28 cases (32 graphics) of cortical infarction (CI) and 16 cases (23 graphics) of stem infarction (SI) with a FLAIR sequence having a repetitive time (TR) of 6500 msec, a TI of 1700 msec and a TE of 110 msec, and compared these graphics with T2-weighted images by spin-echo sequence (TR 2500 msec, TE 90 msec). LI and CI were better demonstrated with FLAIR images than with conventional T2-weighted images. FLAIR images were very useful in detecting lesions adjacent to the lateral ventricles and the cerebral sulci in particular, because the cerebrospinal fluid signals in the lateral ventricles and the cerebral sulci were low-intensity, with brain tissue appearing as high-intensity areas. In a number of old infarctions, FLAIR images revealed cystic structures, constructed out of internal low-intensity areas and peripheral high-intensity areas. These structural changes suggested that FLAIR images can provide information on pathological changes.

Aged↗
PubMed1995

Difference between cancer cells and the corresponding normal tissue in view of stereoselective hydrolysis of synthetic esters.

This study has aimed at taking information necessary for design of anticancer prodrugs modified with chiral acyl group, especially about the effect of chirality of the acyl group on its enzymic removal in specific cells. Thus, 13 species of chiral esters were synthesized and stereoselectivity in their enzymic hydrolysis was investigated with six cancer cell lines, solid tumors, and the corresponding normal tissues. Cultured cancer cells from rat liver, pancreas, and muscle hydrolyzed the R enantiomer of (+/-)-ethyl 2-methoxy-2-phenylacetate (3c) more preferentially than its antipode, whereas this stereoselectivity was reversed in the reaction by homogenate of the corresponding normal tissue of rat. The difference in stereoselectivity between cancer cells and normal tissue was also found in the hydrolysis of other esters including those of actual anticancer agents, p-hydroxyaniline mustard and 5-fluorouridine. The investigation was expanded to real tumor to show that the degree of stereoselectivity or the hydrolytic activity was significantly different between a human brain tumor and its surrounding normal tissue for such substrates as (+/-)-ethyl 2-phenoxypropanoate and N-trifluoroacetylphenylalaninate. The esterases of rat liver cancer cells (Anr4) and normal rat liver gave different band patterns in active staining after gel electrophoresis. The enzymes were fractionated by ion exchange column chromatography and then tested on their stereoselectivity against (+/-)-3c. Comparison of the results and electrophoretograms of the fractions suggests that esterases with different stereoselectivity are expressed in different ways by normal and cancer cells. These results show that stereoselectivity in enzymic hydrolysis of some synthetic chiral esters is different between cancer and normal cells, leading to the possibility that specific activation of ester-type anticancer prodrugs in cancer cells would be controlled by the chiral structure of the acyl group.

Animals↗
PubMed1995

Nuclear morphometry and DNA densitometry of human gliomas by image analysis.

In 48 patients with gliomas in whom complete clinical follow-up was obtained, DNA ploidy was evaluated by using formalin-fixed paraffin-embedded tissues and by means of image analysis. The mean DNA indices, determined by averaging DNA indices of all tumor cells in a tumor, were mainly affected by mean DNA indices of the nuclei of SG2M phase tumor cell (including S phase and G2M phase cells) (SG2M DNA indices) and that mean DNA indices correlated with the SG2M phase fraction. The SG2M DNA indices and the percentage of tumor cells with S phase and G2M phase were higher in high grade gliomas including anaplastic glioma and glioblastoma multiforme than in low grade gliomas. Patients with G2M-hypertetraploid tumors demonstrated a shorter time to tumor progression than those with G2M-tetraploid in high grade glioma. Morphometrically, the nuclei of SG2M phase glioma cells were larger and more deformity than those of G0G1 phase (including G0 phase and G1 phase cells) cells. The G2M-hypertetraploid tumors were highly malignant and demonstrated large nuclei, greater nuclear deformity, and a higher proliferative potential. The G2M-tetraploid gliomas demonstrated a shorter time to tumor progression in cases whose the SG2M fraction was large. In contrast, G2M-hypotetraploid gliomas revealed an insignificant trend towards a longer time to tumor progression than those associated with tetraploid and hypertetraploid gliomas. We emphasize herein the prognostic importance of the SG2M phase cell, as well as other proliferation indices.

Adolescent↗
PubMed1995

Leukoencephalopathy associated with intra-arterial ACNU in patients with gliomas.

Thirty cases of gliomas treated by surgery, radiotherapy and intra-arterial (IA) ACNU were reviewed with a focus on the late side-effect known as leukoencephalopathy. All cases were classified into three groups; remission (10 cases), regrowth (15 cases) and leukoencephalopathy (5 cases) from their outcome. The average total doses of IA ACNU were 49.8 mg/sqm body surface area in the remission group, 157.3 mg/sqm in the regrowth group and 203.1 mg/sqm in the leukoencephalopathy group. There were significant differences in the total IA ACNU doses between the remission group and both regrowth and leukoencephalopathy groups, while no significant differences were noticed in the dose of radiation given. There was a correlation between the total dose of IA ACNU and the occurrence of leukoencephalopathy. An autopsy of a typical case of leukoencephalopathy revealed various degrees of myelin breakdown and thickening of arterial walls, which probably manifested progressive dementia accompanied by urinary incontinence and gait disturbance.

Adolescent↗
PubMed1995

Osteomas of the skull: comparison of magnetic resonance imaging and histological findings.

Magnetic resonance (MR) images of five patients with osteomas of the skull and six patients with other primary skull tumors were reviewed. All osteomas appeared as low-intensity areas on T1-weighted images. T2-weighted images showed homogeneous low-intensity areas in two dense osteomas, a high-intensity area in one spongy osteoma, and mixed intensity areas in two mixed spongy and dense osteomas, respectively. The signal intensities of osteomas on T2-weighted MR images correlated well with the histological findings. Other skull tumors showed no specific MR imaging appearance.

Adolescent↗
PubMed1995

Cerebral gumma mimicking glioblastoma on magnetic resonance images--case report.

A 39-year-old female presented with a syphilitic cerebral gumma mimicking small glioblastoma multiforme manifesting as visual impairment. Magnetic resonance imaging showed a low signal intensity area on T1-weighted images and marked small ring-like enhancement less than 1 cm in diameter following the administration of gadolinium. The symptoms and radiological abnormalities improved several weeks after penicillin therapy. The small ring-like enhancement was probably caused by inflammation associated with treponemal infection. A mass with a small ring-like enhancement less than 1 cm in diameter is a useful finding indicating an inflammatory lesion rather than a glial tumor.

Adult↗
PubMed1995

[Transient cerebellar mutism after removal of a posterior fossa tumor in two cases].

We have reported the cases of two young patients who presented transient mutism in the course of recovery from removal of a cerebellar medulloblastoma. Although cerebellar symptoms were observed immediately after surgery, neither consciousness disturbance nor sensory aphasia was observed when the patients were mutic. From the analysis of serial magnetic resonance imaging (MRI). Gd-enhanced regions were noticed in the dentate nucleus and the cerebellar peduncle when mutism appeared, and they disappeared when mutism was gone. Although the mechanism of this interesting symptom is not clear, these MRI findings may indicate that focal ischemia or edema associated with surgical procedure may play a role in the appearance of this symptom.

Adolescent↗
PubMed1995

[Low incidence of point mutation of N-ras oncogene in human gliomas].

We examined the incidence of point mutations in codon 12 and 61 of N-ras gene in human gliomas using PCR with mismatched primers. This method detects point mutations. PCR with mismatched primers induced restriction sites in normal DNA but not in mutational DNA. Genomic DNAs were extracted from paraffin-embedded tissues and were amplified with nested PCR. Among 17 cases, point mutation has not been able to be found so far, when examined in codon 12 of N-ras gene and among 10 cases in codon 61 of N-ras gene. It can thus be said that point mutational activation of N-ras oncogene is an uncommon event in human gliomas.

Base Sequence↗
PubMed1995

Nuclear characterization and G2M ploidy in human brain tumors using semiautomated image analysis.

We used image analysis to study nuclear morphometry and DNA content in relation to time to tumor progression in a series of 88 patients with brain tumors. Clinical follow-up was obtained for 73 patients. The patients with diploid tumors had a longer time to tumor progression than those with triploid, tetraploid, or hypertetraploid tumors. Mean SG2M-DNA indices (DIs) increased significantly with a increase in mean DIs in all tumors. The mean DIs appeared to be dependent on the number of SG2M phase cells. We conclude that tumors with hypertetraploid in G2M ploidy are highly malignant. Those tumor cells have a large nuclear size, much deformity in nuclear shape, and great proliferative potential. The G2M-tetraploid tumors showed a shorter time to tumor progression when the number of SG2M fractions was large. In contrast, the G2M-hypotetraploid tumors showed a longer time to tumor progression in comparison with other tetraploid and hypertetraploid tumors, but the difference was not significant.

Aneuploidy↗
PubMed1995

UNIX based client/server hospital information system.

SMILE (St. Luke's Medical Center Information Linkage Environment) is a HIS which is a client/server system using a UNIX workstation under an open network, LAN(FDDI&10BASE-T). It provides a multivendor environment, high performance with low cost and a user-friendly GUI. However, the client/server architecture with a UNIX workstation does not have the same OLTP environment (ex. TP monor) as the mainframe. So, our system problems and the steps used to solve them were reviewed. Several points that are necessary for a client/server system with a UNIX workstation in the future are presented.

Computer Communication Networks↗
PubMed1994

Effect of guanidine hydrochloride on the conformation of egg yolk low density lipoprotein.

The denaturation of egg yolk low-density lipoprotein (LDL) induced by guanidine hydrochloride (GdnHCl) has been investigated by using circular dichroism (CD) and fluorescence measurements. The transition curves were obtained from changes of the residue ellipticity at 222 nm and the fluorescence intensity of the aromatic residues, tyrosine and fluorescence. Different transition curves were obtained at the molarities of GdnHCl between 2 and 6 M, and between 1 and 4 M from the CD and the fluorescence measurements, respectively. The noncoincidence of the transition curves as well as the asymmetry of the transition curve obtained from the fluorescence measurements suggests that the denaturation process of LDL consists of several transition states. A very low apparent free energy of denaturation (delta G(app) H2O = 3.0 kcal mol-1) obtained by CD data suggests that LDL has an unstable folded structure in its native state.

Circular Dichroism↗
PubMed1994

Image analysis of nuclear DNA content and morphometric characteristics of the tumor cells in human astrocytomas.

In order to estimate the degree of malignancy of astrocytomas, we applied image analysis to study the nuclear DNA content and morphometric parameters of individual tumor cells in surgically resected specimens of 20 patients. There were nine low grade astrocytomas (LGA) and 11 high grade astrocytomas (HGA). Although the mean DNA index did not indicate a significant difference between LGA and HGA, five (45%) of the 11 HGA had an aneuploid DNA distribution pattern. By contrast, all LGA had a diploid pattern. The ratio of the S-G2M phase (% S-G2M) of the HGA (17.5 +/- 12.3%) was significantly higher than that of the LGA (7.0 +/- 4.6%). From the morphometric analysis of the area and shape of the nucleus of tumor cells, we obtained quantitative estimates of the degree of nuclear pleomorphism in astrocytomas. The nuclei of the tumor cells of HGA had larger sizes, increased anisokaryosis and were more irregular. In contrast to flow cytometry, image analysis can be used for quantitative studies of morphological tumor cell characteristics of relevance in the grading of malignancy.

Adult↗
PubMed1993

The role of thallium-201 single photon emission tomography in the investigation and characterisation of brain tumours in man and their response to treatment.

The aim of this study was to characterise brain tumour type and treatment response in relation to the uptake of thallium-201. 201T1 single photon emission tomography (SPET) was performed in 58 patients with brain tumours. Fifty-six patients were utilised for the statistical comparison of the early and delayed 201T1 indices expressed as the ratio of tumour to contralateral cerebral hemisphere uptake. The retention index of 201T1 in the tumour tissue calculated from the early and delayed scans was also analysed. Furthermore, in 56 patients with 58 brain tumours, a comparison was made of the diagnostic value of high 201T1 uptake and gadolinium diethylene triamine penta-acetic acid (Gd-DTPA) enhancement on MRI scans. Although high 201T1 uptake was observed in viable malignant gliomas, brain metastases, meningiomas and malignant teratoma, the viable malignant gliomas could not be differentiated from brain metastases and extracerebral tumours by means of 201T1 indices. 201T1 SPET failed to diagnose a viable ring-enhanced tumour with a thin rim and small tumours of less than 1.5 cm in diameter visualised by Gd-DTPA-enhanced MRI. In spite of this, 201T1 SPET appears to be effective for determination of the malignant viability of tumours.

Brain↗
PubMed1993

Proton radiation therapy for clivus chordoma--case report.

A 57-year-old male with clival chordoma developed severe hoarseness, dysphagia, and dysphonia 1 month after a second removal of the tumor. Magnetic resonance imaging demonstrated a mass 10 cm in diameter in the region of the middle clivus enhanced inhomogeneously by gadolinium-diethylenetriaminepentaacetic acid, and a defect in the skull base. There was evidence of compression of the anterior surface of the pons. He received proton irradiation employing a pair of parallel opposed lateral proton beams. The dose aimed at the tumor mass was 75.5 Gy, to the pharyngeal wall less than 38 Gy, and to the anterior portion of the pons less than 30 Gy. Time dose and fractionation factor was calculated at 148. Thirty-one months following treatment, he was free of clinical neurological sequelae. Proton therapy should be considered in treatment planning following initial surgical removal or for inoperable clivus chordoma.

Chordoma↗
PubMed1992

Malignancy and viability of intraparenchymal brain tumours: correlation between Gd-DTPA contrast MR images and proliferative potentials.

The feasibility of diagnosing the malignancy and viability of intraparenchymal brain tumours using Gd-DTPA, enhanced and unenhanced T1-weighted MRIs was investigated. The relationship between the Gd-DTPA enhancement pattern, the growth fraction (GF) determined by using the anti-bromide-oxyuridine (BrdU) monoclonal antibody, the clinical condition, the proliferative potential and the change of Gd-DTPA enhancement over time was studied. Forty-five patients with intracranial tumours were studied with the static method of Gd-DTPA MRI. The enhanced effect in Gd-DTPA MRIs was dependent on tumour-cell density, vascularization, necrosis, and dilatation of vascular lumen. Tumour-cells were observed in eighty-seven of eighty-nine specimens taken from areas with Gd-DTPA enhanced MRIs. Seventy-four percent of these specimens (64 of 87) showed a malignancy of more than 5% growth fraction. On the other hand, tumour cells were observed in twenty-seven of fifty-six specimens taken from areas with Gd-DTPA unenhanced MRIs. Eighty-five percent of these specimens (23 of 27) showed a malignancy value of less than 5% GF. However, fifteen percent of these specimen showed values between 5 and 15% GF. In the kinetic study of Gd-MRIs five patients who were in a clinically stable condition and one patient who had radionecrosis showed a constant pattern of enhancement or slightly increased enhancement 30 min after injection compared to 4 min after injection. Therefore, GD-DTPA MRI can be used effectively in the diagnosis of tumour viability and malignancy after treatment.

Brain↗