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Biomedical subjects

Y Takahashi

Publications and source records attributed to Y Takahashi.

At least 19 recordsLinked to original sources
PubMed1992

Aurin tricarboxylic acid inhibits platelet adhesion to collagen by binding to the 509-695 disulphide loop of von Willebrand factor and competing with glycoprotein Ib.

Aurin tricarboxylic acid (ATA) is known to inhibit ristocetin-induced platelet agglutination but not arachidonic acid-, epinephrine- or ADP-induced aggregation. Its capacity to abolish human von Willebrand factor (vWF)-platelet interactions was further investigated by measurement of platelet adhesion to collagen, platelet agglutination tests and binding studies. In flowing blood using parallel-plate perfusion chambers and human collagen, ATA inhibited platelet adhesion to completion in a dose-dependent manner only at the highest shear rate tested (2,600 s-1). It was without effect at 100 and 650 s-1. ATA completely abolished vWF-dependent platelet agglutination induced by ristocetin, botrocetin and asialo-vWF, respectively. 125I-vWF binding to ristocetin- and botrocetin-treated platelets, to heparin and to sulfatides as well as 125I-botrocetin binding to vWF was competitively inhibited by ATA. By contrast, binding of 125I-vWF to collagen was not affected. To further localize the domain of vWF interacting with ATA, experiments of inhibition of binding of selected 125I-monoclonal antibodies (MoAbs) to immobilized vWF by ATA were performed. Our data led to the conclusion that: 1) the interaction of ATA with vWF involves sequences of the A1 disulphide loop of vWF (residues 509-695) and close epitopes which interact with GPIb and 2) the inhibition of platelet adhesion by ATA occurs only at a high shear rate where vWF is known to play a key role. Thus ATA, which blocks the vWF/GPIb pathway by interfering with vWF and not with platelets, is a potential tool in preventing the early stages of thrombosis.

Aurintricarboxylic Acid↗
PubMed1992

[The significance of obesity in UOEH medical students--multiple regression analysis of the annual physical checkup data in 1991].

For the purpose of evaluating the significance of obesity in a young population as a risk factor toward various chronic diseases, a multiple regression analysis was performed on the data from the annual physical checkup of medical students of UOEH in 1991. The following results were obtained. (1) The average obesity index of the students showed a progressive and significant increase in the past 13 years from 1979 to 1991. (2) A close correlation between the obesity index and serum GPT was recognized by elevation of the standard partial regression coefficient of serum GPT to obesity index and that of obesity index to serum GPT when the data from all 617 students was analysed in one group. This finding was intensified in 142 obese students with an obesity index of over 10%, but it was not seen in the remaining non-obese students. (3) The correlation between the obesity index and serum GPT was found solely in the group of students with constant obesity; i.e., whose obesity index was always more than 10% during a maximum of 9 years in the past. (4) Systolic blood pressure was related to the red blood cell count rather than to the obesity index in this young population. (5) No particularly close correlation to serum cholesterol was found with any of 10 representative items examined in this physical checkup, including the obesity index, indicating that the other factors should be related to serum cholesterol levels. From the above findings, it can be concluded that constant obesity in students is related to liver dysfunction, probably due to fatty liver frequently seen in the precise examination of these individuals.

Adolescent↗
PubMed1992

Photoaffinity labeling of the phylloquinone-binding polypeptides by 2-azidoanthraquinone in photosystem I particles.

A photoaffinity label, 2-azido-9,10-anthraquinone, binds at the quinone-binding (Q phi) site with high affinity and can substitute for the secondary acceptor, phylloquinone, in photosystem I reaction center of spinach. Phylloquinone-depleted photosystem I particles reconstituted with azido[3H]anthraquinone were illuminated with UV light and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The large core polypeptides (psaA and/or psaB) were selectively labeled. The labeling was competitively inhibited in the presence of anthraquinone. These results indicate that the Q phi site is located on psaA or psaB polypeptides.

Affinity Labels↗
PubMed1992

A role for Quox-8 in the establishment of the dorsoventral pattern during vertebrate development.

We have been interested in the possible involvement of the gene Quox-8, a member of the Hox-7/msh family of homeobox-containing genes in the patterning of the neural tube and the somitic-derived mesoderm. We demonstrate that in the embryonic day 2-6 avian embryo, the expression of Quox-8 in the roof plate depends upon (i) the normal dorsoventral orientation of the neural primordium and (ii) interactions between the dorsal neural tube and the superficial ectoderm. We also show that Quox-8 is expressed in the dorsal mesenchyme located between the neural tube and the superficial ectoderm that yields the spinous processes of the vertebrae. Experimental inhibition of Quox-8 expression in these areas of the dorsal mesenchyme results in the failure of its differentiation into vertebral cartilage. We conclude, therefore, that this gene is involved in the patterning of vertebral structures through a cascade of tissue interactions primarily occurring between the dorsal neural tube and the overlying ectoderm.

Animals↗
PubMed1992

High levels of nervous system-specific proteins in cerebrospinal fluid in patients with early stage Creutzfeldt-Jakob disease.

Concentrations of several proteins that are characteristic of the nervous system were time-sequentially analyzed by radio- and enzyme-immunoassay in the cerebrospinal fluid (CSF) of patients with Creutzfeldt-Jakob disease (CJD). We found abnormally high levels of several proteins, such as neuron-specific enolase (NSE), S-100b protein, brain-type isozyme of creatine kinase (CK-BB) and alpha subunit of GTP binding protein G0 (G0 alpha) in the early stage of the disease. Generally, these protein levels were far higher in CJD patients than in normal controls and other neurological patients in the early stage before the typical clinical manifestations were evident. These levels increased to maxima when the disease activity was most prominent and returned to normal or mildly elevated levels in the terminal stage. The results imply that these protein levels can serve as biochemical markers for the presence of an active destructive process in CJD brain and provide us with a useful indicator for early diagnosis of CJD.

Brain↗
PubMed1992

Synthesis of 4'-deoxy-4'-fluorokanamycin A and B.

4'-Deoxy-4'-fluorokanamycins A (17) and B (25) have been prepared through fluorinative ring-opening of the D-galacto-3',4'-oxiranes (8 and 21) derived from kanamycin A and B with potassium hydrogenfluoride in ethane-1,2-diol. The mechanism of preponderant formation of the 4'-deoxy-4'-fluoro-D-gluco (9 and 22) over the 3'-deoxy-3'-fluoro-D-gulo derivatives was discussed. In the synthesis of 25, the unusual 3',6'-epimine (23) was the main product along with the 4'-deoxy-4'-fluoro derivative. The mechanism of this reaction is also discussed. Both 17 and 25 were active against resistant bacteria producing aminoglycoside-adenylylating enzymes for HO-4'.

Anti-Bacterial Agents↗
PubMed1992

Activity of chimeric RNAs of U6 snRNA and (-)sTRSV in the cleavage of a substrate RNA.

U6 small nuclear RNA is one of the spliceosomal RNAs essential for pre-mRNA splicing. Discovery of mRNA-type introns in the highly conserved region of the U6 snRNA genes led to the hypothesis that U6 snRNA functions as a catalytic element during pre-mRNA splicing. The highly conserved region of U6 snRNA has a structural similarity with the catalytic domain of the negative strand of the satellite RNA of tobacco ring spot virus [(-)sTRSV], suggesting that the highly conserved region of U6 snRNA forms the catalytic center. We examined whether synthetic RNAs consisting of the sequence of the highly conserved region of U6 snRNA or various chimeric RNAs between the U6 region and the catalytic RNA of (-)sTRSV could cleave a substrate RNA that can partially base-pair with them and have a GU sequence. Chimeric RNAs with 70 to 83% sequence identity with the conserved region of S. pombe U6 snRNA cleaved the substrate RNA at the 5' side of the GU sequence, which is shared by the 5' end of an intron in a pre-mRNA. We found that the highly conserved region of U6 snRNA and the catalytic domain of (-)sTRSV are strikingly similar in structure to the catalytic core region of the group I self-splicing intron in cyanobacteria. These results suggest that U6 snRNA, (-)sTRSV and the group I self-splicing intron originated from a common ancestral RNA, and support the hypothesis that U6 snRNA catalyzes pre-mRNA splicing reaction.

Base Sequence↗
PubMed1992

Localization of gene expression of calbindin in the brain of adult rats.

Localization of gene expression of calbindin, a cytosolic calcium-binding protein, was examined throughout the adult rat brain by in situ hybridization with cDNA probes. The gene was expressed most intensely in the Purkinje cells in the cerebellum, intensely in the granule cells of the dentate gyrus, and moderately in the inferior olivary nucleus, in the nuclei of the trapezoid body, in the medial part of the lateral habenular nuclei, entorhinal cortex and in the mammillary nuclei. In addition, weak expression of the gene was widespread in the forebrain and brainstem gray matter, and also in small cells in the spinal posterior horn as well as the ependymal cells. The widespread and heterogeneous expression of the gene in the brain suggests that calbindin is differentially involved in calcium-regulated phenomena in different neurons.

Animals↗
PubMed1992

Effects of nor-binaltorphimine on the development of analgesic tolerance to and physical dependence on morphine.

The effects of a highly selective kappa antagonist, nor-binaltorphimine (nor-BNI), on the development of tolerance to morphine analgesia and physical dependence on morphine were examined. Pretreatment with nor-BNI (5 mg/kg s.c.) 2 h prior to injection of morphine or a selective kappa agonist, U-50,488H, significantly antagonized the analgesic effect of U-50,488H, but not morphine analgesia in mice. The development of tolerance to morphine analgesia was significantly potentiated by pretreatment of mice with nor-BNI 2 h prior to morphine treatment during chronic morphine treatment for 5 days. Additionally, the pretreatment with nor-BNI during chronic treatment with the high dose of morphine for 5 days significantly potentiated the naloxone-induced body weight loss in morphine-dependent mice and rats. These findings suggest that inactivation of the kappa opioid system may potentiate the development of tolerance to morphine analgesia in mice and may aggravate the naloxone-precipitated body weight loss in morphine-dependent mice and rats.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1992

Mapping of the nu gene using congenic nude strains and in situ hybridization.

The chromosomal location of the nu gene, which is responsible for hairlessness and athymus, was determined using six DNA markers (interleukin 3 [Il-3], Myhs, Acrb, Evi-2, Mpo, and Hox-2) on mouse chromosome 11. We constructed the high-resolution physical mapping of the six DNA markers on chromosome 11 by in situ hybridization using fluorescence-labeled cosmid probes. The results indicate the order of centromere-(41cM)-Il-3-(3cM)-Myhs- (4cM)-Acrb-(6cM)-Evi-2-(3cM)-Mpo-(5cM)- Hox-2. We have used congenic nude strains and examined which of the six DNA markers were derived from the original nude mouse. We found the Evi-2 locus is linked to the nu gene in all the informative, independent congenic nude strains. From these data, we could estimate the location of the nu gene, not only genetically but also physically within a region that spans approximately 17 megabases (9 cM) between the Acrb and Mpo genes.

Animals↗
PubMed1992

Immunoaffinity purification and cDNA cloning of human platelet prostaglandin endoperoxide synthase (cyclooxygenase).

The cDNA for prostaglandin endoperoxide synthase (cyclooxygenase) was cloned from human platelets by the polymerase chain reaction amplification method, and the primary structure of the enzyme was deduced from the nucleotide sequence. The enzyme was composed of 599 amino acids including 23-amino acid signal sequence, and the calculated molecular weight of the mature protein was 65,995. The enzyme was immunoaffinity-purified from human platelets. The N-terminal amino acid sequence determined by Edman degradation was Ala-Asp-Pro-Gly-Ala-Pro-Thr-Pro-, and the result confirmed the primary structure of the enzyme, which was deduced from the cDNA sequence.

Acetylation↗
PubMed1992

parB: an auxin-regulated gene encoding glutathione S-transferase.

We have isolated an auxin-regulated cDNA, parB, from the early stage of cultured tobacco mesophyll protoplasts. The expression of parB was observed during transition from G0 to the S phase of tobacco mesophyll protoplasts cultured in vitro. The predicted amino acid sequence of parB cDNA has 213 amino acid residues with a relative molecular weight of 23,965. Nucleotide sequence analysis revealed that parB cDNA has homology to glutathione S-transferase (GST; RX:glutathione R-transferase, EC 2.5.1.18) from several sources including plant and animal cells. When we introduced expression vector pKK233-2, which retains parB cDNA, into Escherichia coli, we could detect GST activity in the parB gene product. Accordingly a significant increase of GST activity was detected in the tobacco mesophyll protoplasts cultured in the presence of 2,4-dichlorophenoxyacetic acid. This is an example in which the function of auxin-regulated gene product is shown to be ascribed to a specific enzymatic activity. As GST, and its substrate glutathione, are shown to be related to cell proliferation as well as detoxification of xenobiotics in plant and animal cells, the role of parB is discussed in relation to the induction of proliferative activity in differentiated and nondividing mesophyll protoplasts of tobacco.

Amino Acid Sequence↗
PubMed1992

Diabeteslike preproliferative retinal changes in galactose-fed dogs.

Retinal vessel changes were experimentally investigated by a combination of color fundus photography, fluorescein angiography, and histologic studies in beagles that were fed a 30% galactose diet for up to 66 months. Previously, we have described the appearance of pericyte ghosts, microaneurysms, acellular capillaries, and intraretinal hemorrhages in dogs fed a galactose diet for up to 36 months. These disorders were similar to those observed in humans with background diabetic retinopathy. We report herein that dogs fed galactose for 48 to 60 months experience retinal changes associated with the chronic occlusion of capillary beds and subsequent ischemia of the retina. These changes included the appearance of broad areas of nonperfusion, soft exudates (cytoid bodies), intraretinal microvascular abnormalities, occluded arterioles, preretinal and intravitreal hemorrhages, and apparent new vessel growth around the optic disc. The present study clearly demonstrates that the galactose-fed dog is an animal model in which advanced retinal changes develop, and these changes are similar to those associated with preproliferative human diabetic retinopathy.

Animals↗
PubMed1992

cDNA cloning and chromosome assignment of the gene for human brain 14-3-3 protein eta chain.

We present the nucleotide sequence of a cDNA clone of mRNA encoding human 14-3-3 protein, a protein kinase-dependent activator of tyrosine and tryptophan hydroxylases and an endogenous inhibitor of protein kinase C. The 1,730-nucleotide sequence of the cloned cDNA contains 191 bp of a 5'-noncoding region, the complete 738 bp of coding region, and 801 bp of a 3'-noncoding region containing three canonical polyadenylation signals. The 14-3-3 protein eta chain cDNA encoded a polypeptide of 246 amino acids with a predicted molecular weight 28,196. The predicted amino acid sequence of human 14-3-3 protein eta was highly homologous to that of previously reported bovine and rat 14-3-3 proteins with only two amino acid differences. The sequence carries structural features as putative regions responsible for activation of tyrosine and tryptophan hydroxylases and for inhibition of Ca2+/phospholipid-dependent protein kinase C. Northern blot analysis demonstrated widespread expression of the 14-3-3 protein eta chain in cultured cell lines derived from various human tumors. These findings suggest the conservative functions of the 14-3-3 protein among species. Spot blot hybridization analysis with flow-sorted chromosomes showed that the human 14-3-3 protein eta chain gene is assigned to chromosome 22.

14-3-3 Proteins↗
PubMed1992

Cloning of cDNAs encoding human S-100 alpha and beta subunits and their differential expression in human tumor cell lines.

We isolated nearly full-length clones of S-100 alpha and beta subunit cDNAs from a human brain cDNA library. The alpha subunit cDNA was 579 bp long and contained 99 bp of 5'-noncoding region, 282 bp of coding region, and 198 bp of 3'-noncoding region. The beta subunit cDNA was 743 bp long and contained 57 bp of 5'-noncoding region, 276 bp of coding region, and 410 bp of 3'-noncoding region. An amino acid sequence comparison between human and bovine alpha subunits and between human and rat beta subunits showed that both subunits were nearly entirely conserved. The amino acid sequences of human alpha and beta subunits were conserved at both Ca(2+)-binding domains. Northern blot analysis of brain RNA showed that human alpha and beta subunit cDNA probes discriminated between alpha and beta subunit mRNAs. By using these subunit-specific cDNA probes, it was demonstrated that alpha and beta subunit mRNAs were expressed in different manners among tumor cell lines: beta was detected in melanoma and some glioma cell lines, while alpha was detected only in a melanoma cell line. Southern blot analysis showed that there were no major deletions and rearrangements of alpha and beta subunit genes in these cell lines, regardless of the level of alpha and beta subunit expression, suggesting that the expression of these subunits may be regulated at the transcriptional or RNA stability level.

Amino Acid Sequence↗
PubMed1992

Nucleolar organizer regions in prostate cancer.

A silver colloid technique for the staining of nucleolar organizer regions (NORs) was applied to paraffin sections of 52 clinical prostate cancers, 5 incidental carcinomas of the prostate, 12 benign prostatic hypertrophy (BPH) specimens and 7 normal prostates. The mean numbers of silver-stained NORs (AgNORs) in these lesions were 3.12 +/- 0.52 in clinical cancer, 2.65 +/- 0.64 in incidental cancer, 1.66 +/- 0.16 in BPH, and 1.76 +/- 0.22 in normal prostate. There was a statistically significant difference in agNORs numbers between cancer and benign prostatic tissues (p < 0.001). However, no significant difference was observed in AgNORs numbers between incidental and clinical carcinoma of the prostate. In clinical cancer, only poorly differentiated adenocarcinoma showed a statistically larger number of AgNORs than the well or moderately differentiated group (p < 0.02). Correlation between AgNORs numbers and clinical stage was not obvious. There was no relationship between the number of AgNORs and serum values of tumor markers such as PAP, PSA and gamma-Sm. Moreover, the AgNORs numbers did not show a relation to decreasing rates of serum marker levels during successful anti-androgen therapy. If the patients with prostate cancer were divided into two groups by 2.9 of AgNORs number, the group with the smaller number of AgNORs (n = 14) was found to have a tendency towards a longer disease-stabilizing period than the larger group (n = 17).

Androgen Antagonists↗
PubMed1992

NIH3T3 transfectant containing human K-ras oncogene shows enhanced metastatic activity after in vivo tumor growth or co-culture with fibroblasts.

A clone of NIH3T3 transformant (H-3), obtained by transfecting genomic DNA of a human colon carcinoma cell line, contains human K-ras oncogene and yields metastatic pulmonary nodules after intravenous injection of the cells into nude mice. This metastatic ability was enhanced remarkably after in vivo tumor growth (subcutaneous tumor formation in nude mice) accompanied by increased mRNA expression and gene amplification of the human-derived K-ras oncogene, while it declined gradually as the passage number increased in vitro, with corresponding decreases of gene amplification and mRNA expression. Six subclones were randomly selected from H-3 cells which had been subcultured to passage 22. All of the clones in culture showed almost the same low level of metastatic ability and exhibited little K-ras oncogene amplification with correspondingly low mRNA expression. However, after they formed tumors in nude mice, every clone acquired high metastatic ability and the gene amplification increased, with elevated mRNA expression. These experimental facts indicated that acquisition of metastatic ability coupled with the function of K-ras oncogene was conditional in nature, being strongly affected by in vivo tumor circumstances. The low metastatic and G-418-resistant H-3 cells were co-cultured with BALB/c3T3 fibroblasts for 2-4 weeks. After removal of fibroblasts by exposure to G-418, the tumor cells exhibited increased metastatic ability and human K-ras oncogene mRNA, suggesting an intimate interaction between H-3 cells and fibroblasts influencing the function of transfected human K-ras oncogene. Fibroblasts of the host animal may thus have an important role in generating enhanced metastatic activity of H-3 cells.

3T3 Cells↗