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Biomedical subjects

Y Ishimori

Publications and source records attributed to Y Ishimori.

12 recordsLinked to original sources
PubMed2000

Thalamic abnormalities in patients with schizophrenia revealed by proton magnetic resonance spectroscopy.

Recent investigations suggest that thalamic abnormalities may underlie symptom formation in schizophrenia. We previously demonstrated reduced concentrations of N-acetylaspartate (NAA) in tissue from the thalamus of schizophrenic patients using in vitro proton magnetic resonance spectroscopy (1H-MRS). In the present study, in vivo 1H-MR spectra of the left thalamus and frontal lobe were investigated in 20 patients with schizophrenia and 16 age-matched control subjects to replicate our previous postmortem findings and support the hypothesis of thalamic abnormality in schizophrenia. Schizophrenic patients showed significantly lower NAA/total creatine (Cr) and choline-containing compounds (Cho)/Cr ratios in the thalamus than control subjects, while no significant difference was found in the frontal lobe. There was no significant correlation in the schizophrenic patients between the NAA/Cr or Cho/Cr ratio and other clinical data including clinical symptoms or neuroleptic dosage. These findings may further support other studies suggesting decreased thalamic volume or neuronal number and/or thalamic dysfunction, and reduction in size of white matter tracts adjacent to the thalamus in schizophrenia, as well as our previous postmortem MRS study.

Adult↗
PubMed2000

Vascular permeability: quantitative measurement with double-echo dynamic MR imaging--theory and clinical application.

Double-echo dynamic magnetic resonance (MR) imaging was used to evaluate both vascularity and permeability of tissues simultaneously. Vascularity was evaluated on the basis of the T2*-shortening effect due to the intravascular fraction of the contrast agent and permeability on the basis of the T1-shortening effect due to the extravascular fraction. Meningioma was characterized on the basis of higher vascularity and neurinoma on the basis of higher permeability. The proposed method enables better tissue characterization.

Adult↗
PubMed1994

Sequence-specific gene detection with a gold electrode modified with DNA probes and an electrochemically active dye.

A synthesized 20-mer DNA probe complementary to a part of an oncogene v-myc region having a mercaptohexyl group at the 5'-phosphate end was immobilized on a gold electrode by chemisorption. The immobilized DNA was detected voltammetrically using Hoechst 33258 with a DNA minor groove binder and an electrochemically active dye. The modified electrode was immersed into a 100 mumol/L Hoechst 33258 solution and washed with a phosphate buffer (pH 7.0). The anodic peak current (ipa) of Hoechst 33258 on the modified electrode was higher than that on a bare gold electrode (128 and 75 nA, respectively). It was considered that Hoechst 33258 was concentrated on the electrode surface due to its association with DNA. When the modified electrode was hybridized in a solution of a model targeted gene (10(-7) g/mL), single-stranded pVM623 containing the PstI fragment of a 1.5-kilobase pair of oncogene v-myc, the ipa was 192 nA. On the other hand, the ipa was 128 nA when the modified electrode was reacted in a solution of single-stranded pUC119 without a region complementary to v-myc in pVM623. The ipa was related to the concentration of the targeted DNA in the hybridization reaction. The use of Hoechst 33258 resulted in a sequence-specific detection of the targeted DNA quantitatively ranging from 10(-7) to 10(-13) g/mL in a buffer solution.

Base Sequence↗
PubMed1993

Ascidian entactin/nidogen. Implication of evolution by shuffling two kinds of cysteine-rich motifs.

Entactin/nidogen, a major component of the basement membrane, has a domain structure comprising three globular domains, and thread-like and rod-like domains connecting them. It contains six epidermal-growth-factor-(EGF)-like motifs and one thyroglobulin-like motif. In the present study, ascidian entactin/nidogen has been identified by a monoclonal antibody technique. We prepared anti-(ascidian entactin/nidogen)IgG, named anti-AsEnt1, then cloned the cDNA of ascidian entactin/nidogen using anti-AsEnt1 as a probe, and determined its entire sequence. Mainly because the deduced amino acid sequence exhibited high similarity to mouse entactin and human nidogen, and because the antigen localized in basement membrane of ascidian body-wall muscle, we have concluded that the antigen anti-AsEnt1 corresponds to the ascidian entactin/nidogen homologue. The deduced amino acid sequence of ascidian entactin/nidogen clearly showed that the ascidian homologue also has a domain structure. However, the ascidian homologue lacked the thread-like domain, and the rod-like domain differed from that of mouse entactin in composition, consisting of two kinds of cysteine-rich motifs, that is, the EGF-like motif and the thyroglobulin-like motif. These results suggest that entactin/nidogen have evolved by modifying the domains, especially by shuffling the two kinds of cysteine-rich motifs.

Amino Acid Sequence↗
PubMed1993

Stable liposomes for assays of human sera.

We report a novel homogeneous immunoassay system involving protein-bearing liposome-encapsulated carboxyfluorescein as a release marker. We applied this system to determine protein antigens, e.g., ferritin, in human serum samples by a sandwich-type assay. Liposomal lysis was observed in many samples, even though no second antibody was added to the reaction mixture. We demonstrated that the functional groups used to immobilize an antibody on liposomes are related to this phenomenon. Stable liposomes in human sera were prepared by incorporating bromoacetyl groups instead of the dithiopyridyl groups used previously. A good correlation (y = 0.98x - 8.81, r = 0.98, Sx/y = 66.9, range approximately 10-2000 micrograms/L) with results by RIA was obtained in the ferritin measurement of 53 patients' sera by using these liposomes.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

[Experimental brain tumor in adult mongrel cat].

Small animal models such as the rat have serious limitations for multiple human scale instrumentation, surgical manipulations, and computerized tomographic (CT) evaluations, so that large animal models are required for the study using them. Although brain tumors induced with Rous sarcoma virus in neonatal beagle or adult monkey had been reported, these animals are very expensive ones for tumor research. A major drawback of virally induced brain tumor model is, moreover, the need for specialized viral facilities and safety precautions for laboratory personnel. In this paper, a cat glioma model implanted with C6 glioma cells derived from rats injected with N-nitrosomethylurea is reported. For an implantation dose of 5 x 10(5) cells/50 microliters, C6 glioma cells were suspended in modified Eagle medium supplemented with 10% fetal bovine serum and 0.5% agar. Twenty adult mongrel cats were injected with 5 x 10(5) C6 glioma cells intracerebrally. Implanted cats had brain tumors of about 10 mm in diameter with a yield of 80%. The mean survival was about 3 weeks after implantation. Tumors developed as spheroidal, hemorrhagic masses with central areas of necrosis and peripheral edema. They were located within the parenchyma of the implanted region. This tumor possessed many of the histological and radiological characteristics of human glioblastoma such as the following: Areas of hemorrhage and necrosis surrounded by pseudopallisading were observed within the tumor consisting of spindle-shaped cells with pleomorphic nuclei. A mass lesion with ring or garland-like enhancement surrounded by brain edema was shown on the CT scans.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Liposome immune lysis assay (LILA). Application of sandwich method to determine a serum protein component with antibody-bearing liposomes.

A complement-dependent liposome immune lysis assay (LILA) using carboxyfluorescein (CF)-entrapped liposomes bearing antibody was developed to measure C-reactive protein (CRP) antigen as a model of protein antigens in human sera. Goat anti-CRP antibody was covalently coupled to liposomes, and a specific lysis of the liposomes could be observed when the liposomes were incubated with both rabbit anti-CRP antibody (secondary antibody) and CRP antigen in sera in the presence of guinea pig complement. In this assay system, so-called sandwich assay, CRP (a multivalent antigen) bound to the liposomes bearing anti-CRP antibody and subsequently secondary antibody, which activated complement efficiently. The amount of CF released by a complement-dependent liposome immune lysis was proportional to CRP concentrations. This sandwich assay was simple, fast, highly sensitive, and covered the ranges 10-300 ng of CRP/ml in a homogeneous mode, that is, one where no separation step was employed. The results correlated well with those obtained by single radial immunodiffusion and enzyme immunoassay. This assay system would be applicable to the measurement of other protein antigens.

Antibodies↗
PubMed1986

Homogeneous determination of C-reactive protein in serum using liposome immune lysis assay (LILA).

Recently, we have developed an analytical system based on a complement dependent liposome immune lysis assay (LILA) to measure antibody against protein antigens. This paper describes the application of LILA to measure protein antigens by inhibition reaction. We choose human C-reactive protein (CRP), one of acute phase reactants, for a model of antigen determination. CRP antigen is coupled to the carboxyfluorescein entrapped multilamellar liposomes by using N-hydroxysuccinimidyl 3-(2-pyridyldithio) propionate and dithiothreitol, and a specific lysis of liposomes is achieved upon the addition of anti-CRP antibody in the presence of complement. Inhibition of this assay can be observed by the addition of competing amounts of CRP in human serum. This inhibition assay is simple, fast, highly sensitive, reproducible and homogeneous. The assay covers the ranges 10-500 micrograms/l. In an experiment using 50 samples, the results by LILA correlated well with those by single radial immunodiffusion and enzyme immunoassay (correlation coefficient: 0.99 and 0.93, respectively).

Antigens↗
PubMed1984

Liposome immune lysis assay (LILA): a simple method to measure anti-protein antibody using protein antigen-bearing liposomes.

A new simple immunoassay technique using immune lysis of liposomes was developed to measure antibody against protein antigens. Multilamellar liposomes were composed of dipalmitoylphosphatidylcholine, cholesterol and phosphatidylethanolamine substituted with the hetero-bifunctional cross-linking reagent N-hydroxysuccinimidyl 3-(2-pyridyldithio)propionate (SPDP). The protein antigen (human IgG) was coupled to these liposomes after treatment with SPDP and mild reduction. As a release marker, carboxyfluorescein (CF) was entrapped in the liposomes. The CF release was specific to anti-human IgG antibody and depended on the presence of complement. This technique could detect 10(-15) mol of anti-human IgG antibody or human IgG. The liposomes were stable over 8 months at 4 degrees C under nitrogen gas.

Animals↗
PubMedDate not supplied

Research-oriented image registry for multimodal image integration.

To provide multimodal biomedical images automatically, we constructed the research-oriented image registry, Data Delivery System (DDS). DDS was constructed on the campus local area network. Machines which generate images (imagers: DSA, ultrasound, PET, MRI, SPECT and CT) were connected to the campus LAN. Once a patient is registered, all his images are automatically picked up by DDS as they are generated, transferred through the gateway server to the intermediate server, and copied into the directory of the user who registered the patient. DDS informs the user through e-mail that new data have been generated and transferred. Data format is automatically converted into one which is chosen by the user. Data inactive for a certain period in the intermediate server are automatically achieved into the final and permanent data server based on compact disk. As a soft link is automatically generated through this step, a user has access to all (old or new) image data of the patient of his interest. As DDS runs with minimal maintenance, cost and time for data transfer are significantly saved. By making the complex process of data transfer and conversion invisible, DDS has made it easy for naive-to-computer researchers to concentrate on their biomedical interest.

Computer Communication Networks↗
PubMedDate not supplied

Blood volume of gliomas determined by double-echo dynamic perfusion-weighted MR imaging: a preliminary study.

BACKGROUND AND PURPOSE: After bolus injection, gadopentetate dimeglumine causes a T2* rate change in permeable tissue that is contaminated by the T1 shortening effect due to the leakage of contrast agent. Therefore, tumor vascularity as reported in previous single-echo perfusion-weighted MR imaging studies has been underestimated. Our aim was to quantitatively and qualitatively evaluate the degree of blood volume of glioblastoma multiformes (GBMs) underestimated by this T1 shortening effect. METHODS: We used double-echo dynamic MR imaging after a bolus injection of gadopentetate dimeglumine (double-echo perfusion-weighted MR imaging) to simultaneously determine tumor blood volume without (V(T1U)) and with (V(T1C)) T1 shortening correction. MR imaging was performed in five consecutive patients with GBMs. The ratios of V(T1U) and V(T1C) were calculated and compared by means of quantitative analysis. The degree of tumor blood volume as determined by V(T1U) and V(T1C) maps were qualitatively compared using a three-point scale. RESULTS: All GBMs showed contrast enhancement on postcontrast T1-weighted images. In all subjects, the values of V(T1U) were significantly lower than those of V(T1C) (mean +/- SD, 2.05 +/- 1.01 vs. 3.62 +/- 1.40, respectively [P <.05]), indicating that tumor blood volume obtained by double-echo perfusion-weighted MR imaging was significantly higher than that by single-echo imaging. In the qualitative analysis, tumor blood volume on the V(T1U) map was less conspicuous than that on the V(T1C) map. CONCLUSION: Careful attention should be paid to the underestimation of tumor blood volume resulting from T1 shortening effects when using single-echo perfusion-weighted MR imaging. Double-echo imaging may be more suitable for the analysis of blood volume in GBMs.

Adult↗