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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 271 records · Page 15Linked to original sources
PubMed2000

[Technology and application of DNA array].

Recently DNA macro and micro array has just begun to use for analysis of DNA expression. The array technique allows us to analyze expression pattern of several hundreds and thousands of genes simultaneously. The array method enables us to analyze gene expression levels of each gene among different samples, however it does not provide comparative analysis of the expression level of multiple genes in a single array. Because intensity of each signal on the array is normalized by the expression intensity of several standard house keeping genes, intensity of signals of each genes among different array can be compared by the number of relative intensity based on normalization. Such characteristic feature of array allows us to analyze potential function of the genes even though function of genes are not known or well characterized.

Animals↗
PubMed2000

[Clinical role of cell cycle regulators in androgen-dependent cancer cell growth].

The functional and quantitative alterations in cell cycle regulators after androgen depletion in an androgen-dependent cancer cell and the interaction between androgen receptor and cell cycle regulators were examined in order to clarify the initial response of cancer cells to anti-androgen therapy. Fluorescence activated cell sorter analysis (FACS) of androgen-dependent cancer cell line (SC-3) cells cultured with or without 1 nM dihydrotestosterone (DHT) revealed that suppression of cell growth after androgen withdrawal was due to G1 arrest. The protein level of cyclin D1 decreased without any apparent change in the amounts of Cdk2, Cdk4, cyclin E or cyclin A. Among various Cdk inhibitors (CKIs) examined, p27 was upregulated at both mRNA and protein levels 24 h after androgen depletion. On the other hand, cyclin E has been shown to increase the transactivation activity of the human androgen receptor (AR) in the presence of DHT. These results suggest that cell cycle regulators are critical targets in the initial response of androgen-dependent cancer cells to androgen depletion and play a key role in the transcriptional activity of AR.

Androgens↗
PubMed2000

[A case of Ondine curse associated with a medullary tumor].

A 49-year-old woman with 6 months history of body weight loss, muscle weakness, and dysarthria, was found with respiratory arrest and resuscitated in the morning of January 1999. An MRI brain scan revealed diffuse swelling and T2/FLAIR high signal intensity with mild Gadolinium enhancement in the lower pons and medulla oblongata. Although the histological diagnosis could not be obtained, glioma (astrocytoma) was suspected. In the morning of July 3rd she presented sweating and cyanosis. Her arterial oxygen saturation was 18%. When we asked her to breathe more, she kept breathing and oxygen saturation was normalized. However, she could not breathe at all when she fell asleep without stimulation. She was kept under respiratory support for 2 months. Her symptoms improved with fluctuating course after 70 Gy of radiation therapy. Ondine curse is one type of sleep apnea syndrome, defined as the selective disturbance of autonomous breathing. Surgical operation and stroke are the reported causes of this syndrome. Brainstem tumor is relatively common cause for children's Ondine curse. On the other hand, it rarely causes adult's Ondine curse as a main symptom.

Astrocytoma↗
PubMed2000

[CADASIL: clinical analysis of CADASIL and CADASIL-like disorders in Japan].

To clarify the characteristics of CADASIL in Japan, we performed clinical and genetic investigations for six patients from 5 Japanese families diagnosed as CADASIL. We identified that the onset of focal neurologic deficits ranged from 38 to 63 years old (mean 49 +/- 9.4 yrs) and the occurrence rates of main neurologic symptoms and signs were 1/6 for migraine, 3/6 for recurrent stroke episodes, 6/6 for dementia, and 4/6 for pseudobulbar palsy. The marked narrowing of retinal arteries were observed in 3/6. The notch 3 mutations were all found in exon 4. Although other several families shared similar phenotype of CADASIL, there were no deposition of granular osmiophilic materials within the basal lamina of smooth muscle cells in the arterioles of biopsied muscle and no mutations in the cording regions of notch 3 gene. We investigated prospectively the incidence of CADASIL and CADASIL-like disease in Kumamoto district from 1999 to 2000. One thousand and thirty four patients with stroke were hospitalized in 6 hospitals which have stroke care unit. Among them, 7 patients fulfilled the criteria that were less than 60 years old, lacunar strokes and/or TIA, presence of a family history, and no risk factors such as hypertension, diabetes mellitus, and hyperlipidemia. One of seven patients was diagnosed as CADASIL by DNA analysis. It was suspected the incidences of CADASIL and CADASIL-like disease were not so rare in Japan.

Cerebral Infarction↗
PubMed1999

Identification, sequence analysis and phylogeny of the lef-2 gene of Helicoverpa armigera single-nucleocapsid baculovirus.

The baculovirus late expression factor 2 (LEF-2) is involved in DNA replication, and most likely function as a primase processivity factor. Lef-2 genes have been found in multinucleocapsid nucleopolyhedroviruses (MNPVs) and in granuloviruses (GVs), but not yet in single-nucleocapsid NPV (SNPV). Here, a lef-2 gene homolog was identified from SNPV of Helicoverpa armigera (HearNPV). The open reading frame of the HearNPV lef-2 gene is 696 nucleotides long, encoding a putative protein of 232 amino acids with an M(r) of about 26 kDa. The 5'-noncoding region contains two early (CAGT) consensus motifs for transcription initiation and three TATA boxes. Lef-2 transcripts started at a C, 29 nucleotides upstream of a putative translational start. A putative polyA signal, AATAAA, was found 76 nucleotides downstream of the translation stop codon. The HearNPV lef-2 gene has a low but significant degree of amino acid sequence identity (30%) to the lef-2 genes of 15 other baculoviruses of which nine were newly determined. The N-terminal half of the LEF-2 proteins contains one (I) and the C-terminal half two (II and III) conserved domains. Sixteen amino acids are absolutely conserved in those LEF-2 investigated and are probably critical for LEF-2 function. A phylogenetic tree of 16 baculovirus LEF-2 proteins was constructed by using maximum parsimony analysis and appeared to be comparable to a tree for ecdysteroid UDP-glucosyl transferases (Chen et al., 1997a). The genomic location of the lef-2 genes relative to polyhedrin/granulin and the clade structure of the gene trees suggest that genome organization and gene phylogeny are useful parameters to study the evolutionary history of baculoviruses. These two independent approaches also give a more complete picture of the ancestral relationship among baculovirus.

Amino Acid Sequence↗
PubMed1999

Gender differences in expression of organic cation transporter OCT2 in rat kidney.

The organic cation transporter (OCT) mediates translocation of various cationic molecules including drugs, toxins and endogenous substances. We examined gender differences in the expression of rat (r) OCT2 in the kidney. Slices and basolateral membrane vesicles of male rat kidney showed a higher transport activity for tetraethylammonium than those of female rat kidney. The expression levels of rOCT2 mRNA and protein in the kidney of males were much higher than those in females. There was no gender difference in mRNA expression of rOCT1 and rOCT3. These findings suggest that rOCT2 is responsible for the gender differences in renal basolateral membrane organic cation transport activity.

Animals↗
PubMed1999

Non-adherent cell-specific expression of DOCK2, a member of the human CDM-family proteins.

Human DOCK180, which was originally identified as a major protein bound to the Crk oncogene product, is an archetype of the CDM family of proteins, including Ced-5 of Caenorhabditis elegans and Mbc of Drosophila melanogaster. After DOCK180, at least three putative human proteins that manifest high amino acid sequence similarity to DOCK180 have been registered in the GenBank/EMBL database. We have designated one of them, KIAA0209, as DOCK2 and characterize here. DOCK2 mRNA was expressed mostly in peripheral blood cells, followed by slight expression in the spleen and thymus, whereas DOCK180 was expressed in all tissues tested except in peripheral blood cells. Immunostaining of human cadaver tissues revealed that the expression of DOCK2 was limited to the lymphocytes and macrophages of various organs. DOCK2 bound to and activated Rac1, as did DOCK180; however, DOCK2 did not bind to CrkII, which transduces signals at focal adhesions. Thus, DOCK180 and DOCK2 are regulators of Rac and function in adherent and non-adherent cells, respectively.

Amino Acid Sequence↗
PubMed1999

Comparison between in vivo and in vitro pharmacokinetics of succinylcholine in humans.

PURPOSE: To compare the in vivo and in vitro pharmacokinetics of succinylcholine (SCh) in humans. METHODS: A bolus of SCh 1 mg.kg(-1) (n = 7) or 2 mg.kg(-1) (n = 11) was given to 18 patients anesthetized with thiopental. Arterial blood samples for determination of in vivo SCh concentrations were collected every 30 s for 5 min. Another 20-ml blood sample was obtained before induction of anesthesia for determination of in vitro SCh. Concentrations of SCh were measured by high-performance liquid chromatography. In vivo and in vitro concentrations of SCh vs time data were analyzed by the one-compartment model. RESULTS: The respective in vivo and in vitro pharmacokinetic parameters (SCh 1 mg.kg(-1) vs SCh 2 mg.kg(-1)) were as follows: Plasma clearance was 4.17 +/- 2.37 and 1.85 +/- 0.28 l.min(-1), P < 0.05, vs 2.91 +/- 2.01 and 1.27 +/- 0.43 l.min(-1), P < 0.05. Elimination half-life was 25.4 +/- 10.6 and 47.4 +/- 5.4 s, P < 0.002 vs 26.3 +/- 10.0 and 75.2 +/- 21.8 s, P < 0.00005. CONCLUSION: These results suggest that the rapid disappearance of SCh from the circulation is due to diffusion out of the blood vessels rather than to enzymatic hydrolysis.

Journal Article↗
PubMed1999

Effect of dipyridamole on QT dispersion in vasospastic angina pectoris.

Life-threatening ventricular arrhythmias have frequently been documented in patients with vasospastic angina. Moreover, the incidence of ventricular arrhythmias has been closely associated with increased QT dispersion. However, the underlying mechanism responsible for this arrhythmogenesis has not been clarified. The effects of dipyridamole and subsequent aminophylline administration on QT dispersion were examined in 35 patients with vasospastic angina and 30 patients with atypical chest pain. None of the patients enrolled in this study revealed any significant stenosis in coronary angiography. QT dispersion during dipyridamole followed by aminophylline administration was compared between the 2 groups. The baseline QT dispersion was similar in both groups (vasospastic angina: 27 +/- 8 ms; atypical chest pain: 28 +/- 7 ms). No significant changes in QT dispersion were observed in patients with atypical chest pain by dipyridamole (23 +/- 9 ms) and subsequent aminophylline administration (23 +/- 5 ms). However, the QT dispersion in patients with vasospastic angina increased significantly by dipyridamole administration (53 +/- 14 ms, p <0.0001) and returned to baseline by subsequent aminophylline administration (26 +/- 10 ms). Our data suggest that the disparity of ventricular repolarization in vasospastic angina may be mediated by increased endogenous adenosine.

Adult↗
PubMed1999

Functional analysis of rat renal organic anion transporter OAT-K1: bidirectional methotrexate transport in apical membrane.

Renal organic anion transporter OAT-K1 was stably transfected in MDCK cells and examined for its transport characteristics and membrane localization. OAT-K1 mediated both uptake and efflux of methotrexate in the apical membranes. Immunoblotting showed that the apparent molecular mass of the expressed OAT-K1 was 50 kDa, which was comparable to that found in the rat renal brush-border membranes. The OAT-K1-mediated methotrexate transport was significantly inhibited in the presence of several organic anions such as folate and sulfobromophthalein. These findings suggest that OAT-K1 mediates bidirectional methotrexate transport across the apical membranes, and may be involved in the renal handling of methotrexate.

Animals↗
PubMed1999

Malignant transformation of NIH3T3 cells by overexpression of early lymphocyte activation antigen CD98.

CD98, which forms a heterodimer of relative molecular mass (M(r)) 125, 000, was originally identified as an early T cell activation antigen. It consists of a heavy chain of M(r) 85,000 that bears the CD98 epitope and a light chain of M(r) 40, 000. CD98 is strongly expressed on the surface of activated lymphocytes and various tumor cells irrespective of tissue origins. To investigate the participation of CD98 in cellular proliferation and malignant transformation, we established and characterized human CD98-transfected NIH3T3 clones. Although the doubling times of the control cells and CD98-transfected clones were almost the same, CD98-transfected clones grew to a higher saturation density than control cells. Effciency of colony formation in soft agar was augmented in CD98-transfected clones, and this augmentation was significantly reduced by anti-human CD98 mAb. Furthermore, CD98-transfected clones developed tumors in athymic mice. These results indicated that overexpression of CD98 participates in the process of malignant transformation, suggesting that CD98 has oncogenic potential.

3T3 Cells↗
PubMed1999

A single nucleotide insertion in the 5'-untranslated region of hepatitis C virus leads to enhanced cap-independent translation.

The 5'-untranslated region (5'-UTR) of hepatitis C virus (HCV) contains an internal ribosome entry site (IRES) that directs translation of the viral open reading frame (ORF). The 5'-UTR consists of 341 nucleotides (nt) in most strains, and multiple segments within this region are important for its IRES activity. Sequencing analysis of a full-length HCV cDNA clone derived from a Japanese HCV1b-positive patient showed the 5'-UTR was 342 nt long due to a nucleotide T insertion at position 207. The influence of this T insertion on the IRES activity in directing cap-independent translation was investigated. The IRES of the 5'-UTR342 was approximately five- and two- to sevenfold more active in directing luciferase expression in monocistronic and bicistronic expression systems, respectively, when compared with the IRES of the 5'-UTR341 of a previously reported HCV1b strain. In addition to the T insertion, another point mutation involving an A to C transition at position 119 was also present in the 5'-UTR342. Simultaneous comparison of the IRES activities in engineered constructs that contained each of the two mutations indicated that the insertion at position 207 is responsible for the enhanced IRES activity of the 5'-UTR342. Further determination of the abilities of the engineered 5'-UTRs harbouring A, G, or C insertions at the same position to initiate translation indicated that both T and non-T nucleotide insertions lead to enhanced cap-independent translation.

5' Untranslated Regions↗
PubMed1999

Effects of glucagon on axoplasmic transport in mouse superior cervical ganglion cells.

The effects of glucagon on the axoplasmic transport of cultured mouse superior cervical ganglion cells were analyzed with the video-enhanced DIC microscope system. Glucagon increased the rate of fast axoplasmic transport by 30% in both anterograde and retrograde directions. The average velocity was increased from 1.36 +/- 0.48 microns/s to 1.74 +/- 0.43 microns/s (anterograde, n = 60) and from 1.37 +/- 0.48 microns/s to 1.62 +/- 0.39 microns/s (retrograde, n = 60). The stimulatory effect of glucagon on the axoplasmic transport was reversed in a glucose-free medium, whereas blocking the citrate cycle by pretreating neuronal cells with malonate did not alter the effect of glucagon. Together with our previous findings, our data suggest that neurotransmitters and hormones play a major role in the regulation of fast axoplasmic transport.

Animals↗
PubMed1999

Effect of eluent composition on retention behavior of anions in ion chromatography on anion-exchangers modified with heparin.

Effect of eluent composition on retention behavior of inorganic anions have been investigated in ion chromatography using anion-exchangers modified with heparin. Both cation and anion of the eluent affected the retention of analyte anions and unusual retention behavior was observed on the modified stationary phase. The retention time of anions decreased with decreasing eluent concentration when sodium sulfate, magnesium sulfate and chlorides of alkali metals were used as the eluent, whereas it increased with decreasing eluent concentration when aluminum sulfate, copper sulfate and sulfuric acid were used as the eluent. The retention of nitrate increased in the order of Li+, Na+, K+, Rb+ and Cs+ when their chlorides were used as the eluent. When sodium perchlorate and chlorides of alkaline-earth metals were used as the eluent, the eluent should include heparin. Otherwise, the modifier was partially bled from the column.

Anions↗
PubMed1999

Inhibitory effect of KW-3902, an adenosine A(1) receptor antagonist, on p-aminohippurate transport in OK cells.

KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine) is a novel potent and selective adenosine A(1) receptor antagonist. We examined the effect of KW-3902 on p-aminohippurate (PAH) transport in opossum kidney (OK) epithelial cells. Pretreatment for 3 h with KW-3902 inhibited the transcellular transport of PAH across OK cell monolayers from the basal to the apical side. The uptake of PAH across the basolateral membrane of OK cells was inhibited by KW-3902 pretreatment in a time- and concentration-dependent manner. A kinetic analysis revealed that the inhibitory effect of KW-3902 on the basolateral PAH uptake was due to an increase in the Michaelis constant (K(m)) as well as a decrease in the maximum uptake rate (V(max)), showing that the inhibition was a mixed type. Pretreatment with adenosine deaminase or 8-cyclopentyl-1,3-dipropylxanthine, another selective adenosine A(1) receptor antagonist, also decreased the basolateral PAH uptake. KW-3902 pretreatment had no effect on the concentration of intracellular alpha-ketoglutarate which exchanges for PAH across the basolateral membrane of OK cells. These results suggest that KW-3902 has an inhibitory effect on PAH transport in OK epithelial cells.

Adenosine Deaminase↗
PubMed1999

Effects of glycosylation on the structure and dynamics of eel calcitonin in micelles and lipid bilayers determined by nuclear magnetic resonance spectroscopy.

The three-dimensional structures of eel calcitonin (CT) and two glycosylated CT derivatives, [Asn(GlcNAc)3]-CT (CT-GlcNAc) and [Asn(Man6-GlcNAc2)3]-CT (CT-M6), in micelles were determined by solution NMR spectroscopy. The topologies of these peptides associated with oriented lipid bilayers were determined with solid-state NMR. All of the peptides were found to have an identical conformation in micelles characterized by an amphipathic alpha-helix consisting of residues Ser5 through Leu19 followed by an unstructured region at the C-terminus. The overall conformation of the peptide moiety was not affected by the glycosylation. Nevertheless, comparison of the relative exchange rates of the Leu12 amide proton might suggest the possibility that fluctuations of the alpha-helix are reduced by glycosylation. The presence of NOEs between the carbohydrate and the peptide moieties of CT-GlcNAc and CT-M6 and the amide proton chemical shift data suggested that the carbohydrate interacted with the peptide, and this might account for the conformational stabilization of the alpha-helix. Both the unmodified CT and the glycosylated CT were found to have orientations with their helix axes parallel to the plane of the lipid bilayers by solid-state NMR spectroscopy.

Acetylglucosamine↗
PubMed1999

Fas modulates both positive and negative selection of thymocytes.

We studied the functional role of Fas (CD95) in thymic T cell development using the TCR transgenic mice homozygous for the lpr mutation, DO10 lpr/lpr mice. In DO10 lpr/lpr mice, the differentiation of CD4(+)CD8(+) double-positive (DP) thymocytes to CD4(+) single-positive (SP) thymocytes was markedly impaired, as indicated by decreased generation of CD4(+) SP thymocytes and reduced ratio of CD4(+) SP thymocytes to DP thymocytes in lpr/lpr mice compared with those of +/+ mice. Activation of DP thymocytes in the process of positive selection was also significantly inhibited in DO10 lpr/lpr mice, as shown by the lower levels of CD69 expression on DP thymocytes in lpr/lpr mice compared to +/+ mice. Furthermore, the deletion of DP thymocytes induced by in vivo administration of OVA peptide (up to 150 micrograms) and anti-TCR clonotype mAb did not occur in DO10 lpr/lpr mice, whereas these treatments significantly decreased DP thymocytes in DO10 +/+ mice. On the other hand, no significant difference in DO10 transgenic TCR expression on DP thymocytes was found between DO10 lpr/lpr and +/+ mice. Together, these results indicate that Fas is importantly involved in both positive and negative selection of thymocytes.

Amino Acid Sequence↗