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Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 685 records · Page 38Linked to original sources
PubMed1995

Identification of Kv1.1 expression by murine CD4-CD8- thymocytes. A role for voltage-dependent K+ channels in murine thymocyte development.

The patch-clamp recording technique and RNA-polymerase chain reaction were used to identify the voltage-dependent K+ channels expressed by murine fetal and adult CD4-CD8- thymocytes. Two distinct currents, encoded by the genes Kv1.1 and Kv1.3 were identified based upon their biophysical and pharmacologic characteristics and confirmed with RNA-polymerase chain reaction. Peptide blockers of Kv1.1 and Kv1.3 gene products were also applied to a murine fetal thymic organ culture system to investigate the developmental role of these K+ channels. Dendrotoxin (DTX) and charybdotoxin (CTX), antagonists of Kv1.1 and Kv1.3 channels, respectively, decreased thymocyte yields in organ culture without affecting thymocyte viability. DTX-treated thymi contained 56 +/- 8% (n = 8 experiments), and CTX-treated thymi contained 74 +/- 4% (n = 7 experiments) as many thymocytes as untreated lobes. DTX and CTX also altered the developmental progression of thymocytes in fetal organ culture. These data provide the first evidence of Kv1.1 expression in a lymphoid cell and indicate that thymocyte voltage-dependent K+ channels are critical to thymocyte preclonal expansion and/or maturation.

Animals↗
PubMed1995

Rapid ventricular induction of brain natriuretic peptide gene expression in experimental acute myocardial infarction.

BACKGROUND: We have demonstrated that brain natriuretic peptide (BNP) is a cardiac hormone predominantly synthesized in and secreted from the ventricle. We have also reported that, compared with atrial natriuretic peptide (ANP), the plasma concentration of BNP is increased to a greater degree in patients with congestive heart failure and more rapidly in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: To investigate ventricular gene expression of BNP in AMI, we analyzed plasma and ventricular BNP concentrations along with ventricular BNP mRNA in rats with AMI produced by coronary artery ligation. The BNP concentration in the left ventricle increased about 2-fold as early as 12 hours postinfarction and 5-fold 1 day postinfarction compared with sham-operated rats, whereas left ventricular ANP concentration remained unchanged within 1 day. The tissue concentration of BNP increased in the noninfarcted region as well as in the infarcted region. The surviving myocytes in and around the necrotic tissues in the infarcted region were intensely stained with the anti-BNP antiserum, indicating augmented production in the remaining myocytes in the infarcts. The BNP concentration in the right ventricle also increased about 10-fold 12 hours postinfarction, whereas the ANP concentration remained unchanged within 12 hours. Northern blot analysis revealed that BNP mRNA expression was augmented 3-fold in the left ventricle as early as 4 hours postinfarction. In contrast, ANP mRNA expression was unchanged. Reflecting the rapid induction of ventricular BNP production, the plasma BNP concentration rose to about 100 pg/mL 12 hours postinfarction (sham-operated rats, < 70 pg/mL). CONCLUSIONS: These results demonstrate the rapid induction of ventricular BNP gene expression in rats with AMI compared with ANP and suggest that BNP gene expression in the ventricle is regulated distinctively from ANP gene expression against acute ventricular overload. They also suggest that the BNP gene can be one of the acutely responsive cardiac genes for the ventricular overload and suggest a possible pathophysiological role of BNP distinct from ANP in AMI.

Animals↗
PubMed1995

An inhibitory role for phosphatidylinositol 3-kinase in insulin secretion from pancreatic B cell line MIN6.

Phosphatidylinositol 3-kinase (PI3-kinase) has been implicated in the regulation of vesicular transport. We examined the roles of PI3-kinase in the glucose-induced insulin secretion from the pancreatic beta cell line MIN6 by using wortmannin, a potent inhibitor of PI3-kinase. Low concentrations of wortmannin markedly potentiated the glucose-induced insulin secretion. This effect was probably mediated by PI3-kinase inhibition. Furthermore, wortmannin completely canceled the suppressive effect of insulin-like growth factor-I on insulin secretion from MIN6 cells. On the basis of these results, we discuss a possible role of PI3-kinase in the negative feed-back regulation of insulin secretion.

Androstadienes↗
PubMed1995

2-Methoxy-4-nitroaniline is a selective inducer of cytochrome P450IA2 (CYP1A2) in rat liver.

Male F344 rats were treated with a chemical (aniline, nitrobenzene, 2-methoxy-p-phenylenediamine, 2-methoxy-4-nitroaniline or 2-methoxy-4-nitroazobenzene) produced by the azo-reduction and/or N-oxidation of 2-methoxy-4-amino-azo-benzene, a selective inducer of cytochrome P450IA2 (CYP1A2), and their effects on the induction of CYP1A enzymes in the liver were examined in terms of the protein and mRNA amounts. 2-Methoxy-4-nitroaniline and 2-methoxy-4-nitroazo-benzene, but not other compounds tested, induced CYP1A enzymes, especially CYP1A2, as assessed by Western blotting and Northern blotting. It is noteworthy that 2-methoxy-4-nitroaniline was more selective than 2-methoxy-4-aminoazobenzene for induction of CYP1A2, and it has the smallest molecular size among the known CYP1A2 inducers.

Aniline Compounds↗
PubMed1995

Preparation of long-circulating immunoliposomes containing adriamycin by a novel method to coat immunoliposomes with poly(ethylene glycol).

Modifications of liposomes with poly (ethylene glycol) (PEG) have been reported to prolong blood circulation time of liposomes. In this report, an adriamycin-encapsulated immunoliposomes were modified with PEG by two different approaches: one is the pre-coating method using lipid derivative of PEG as described by Allen et al. The other is post-coating method which is presented here. The former pre-coating method did not allow coupling of antibody due to the steric hindrance of PEG which had been introduced on liposome surface. On the other hand, in the later post-coating method, PEG-succinylcysteine was synthesized and was successfully conjugated with immunoliposomes via maleimido linker. Resultant PEG-coated immunoliposomes containing adriamycin retained their binding activity and cytotoxicity to target cells, and also showed significantly prolonged blood circulating time as compared with conventional immunoliposomes. This is a novel method to coat immunoliposomes with PEG.

Animals↗
PubMed1995

LckBP1, a proline-rich protein expressed in haematopoietic lineage cells, directly associates with the SH3 domain of protein tyrosine kinase p56lck.

The Lck tyrosine kinase molecule plays an essential role in T cell activation and T cell development. Using the expression cloning technique, we have isolated a gene that encodes a molecule, LckBP1, able to associate with murine Lck. Analysis of full-length LckBP1 cDNA indicates at least four potentially important segments: a four tandem 37 amino acid repeat motif with a potential helix-turn-helix DNA binding motif; a proline-rich region; a proline-glutamate repeat; and an SH3 domain. These four regions are very similar to the human haematopoietic-specific protein 1 (HS1). Deletion mutant analysis of LckBP1 revealed two proline-rich regions that permit association with Lck SH3. One region contains prolines conserved among HS1 and cortactin, and the other region contains a potential MAP kinase recognition site. In vivo association between Lck and LckBP1 was confirmed by immunoprecipitation of lysates from a pre-T cell line and adult thymocytes using antibodies specific for Lck and LckBP1. LckBP1 is tyrosine phosphorylated after T-cell receptor stimulation. The SH3 domain and the potential helix-turn-helix motif in LckBP1 suggest that this molecule may associate with various molecules and function as a DNA binding molecule. The data also suggest that LckBP1 mediates intracellular signalling through Lck in T cells.

3T3 Cells↗
PubMed1995

Homeostatic regulation of intestinal epithelia by intraepithelial gamma delta T cells.

Although T cells bearing gamma delta T-cell receptors have long been known to be present in the epithelial lining of many organs, their specificity and function remain elusive. In the present study, we examined the intestinal epithelia of T-cell-receptor mutant mice, which were deficient in either gamma delta T cells or alpha beta T cells, and of normal littermates. The absence of gamma delta T cells was associated with a reduction in epithelial cell turnover and a downregulation of the expression of major histocompatibility complex class II molecules. No such effects were observed in alpha beta T-cell-deficient mice. These findings indicate that intraepithelial gamma delta T cells regulate the generation and differentiation of intestinal epithelial cells.

Animals↗
PubMed1995

Effects of acetylcholine and adrenaline on axoplasmic transport at different regions of mouse superior cervical ganglion cells in culture.

Adrenaline and acetylcholine (ACh) were applied locally at three different positions in cultured superior cervical ganglion cells, i.e., cell body, neurite, and growth cone and the effects on the axoplasmic transport were measured with a video-enhanced microscope. Local ACh application to the cell body, neurite, and growth cone caused the same decreasing effect, but the effects of local adrenaline application were different from each other. Local adrenaline application to the cell body and growth cone caused an increase of axoplasmic transport, but local application at the neurite caused no effect. These data may indicate that there was a lack of beta 2 adrenergic receptors in the neurite. Desensitization of axoplasmic transport was also examined in the SCG neurons. Repetitive adrenaline application to the cell body caused desensitization to the stimulus of adrenaline application.

Acetylcholine↗
PubMed1995

Regulation of early T cell development by the engagement of TCR-beta complex expressed on fetal thymocytes from TCR-beta-transgenic scid mice.

Transgenic expression of the beta-chain of T cell antigen-receptor (TCR) is known to induce the generation of CD4+ CD8+ thymocytes in the immunodeficient scid mouse, in which thymocyte development is otherwise arrested at CD4- CD8- cells. It is not clear, however, whether or not the thymocyte development is controlled by ligand engagement of the TCR-beta complex on the cell surface. In the present study, we have examined how the engagement by Ab of the TCR-beta complex expressed on the TCR-beta-transgenic scid fetal thymocytes can regulate the generation of CD4+ CD8+ thymocytes. Organ cultures of CD4- CD8- day 14 fetal thymocytes from the TCR-beta-transgenic scid mice resulted in the generation of CD4- CD8+ and then CD4+ CD8+ cells. The initial step from CD40- CD8- cells to CD4- CD8+ cells was enhanced by the addition of anti-TCR-beta Ab, whereas the subsequent step from CD4- CD8+ cells to CD4+ CD8+ cells was markedly inhibited by anti-TCR-beta Ab. These results indicate that ligand engagement of the TCR-beta complex can positively and negatively regulate the early thymocyte development. Moreover, the finding that engagement of TCR-beta complex inhibits the generation of CD4+ CD8+ cells suggests that the induction of CD4+ CD8+ thymocytes by the TCR-beta transgene is not an immediate consequence of cell-surface engagement of the TCR-beta complex but requires liberation from the continued TCR-beta signaling.

Animals↗
PubMed1995

Ustiloxins, new antimitotic cyclic peptides: interaction with porcine brain tubulin.

Biochemical and electron microscopic studies demonstrated that ustiloxins A-D, which are antimitotic 13-membered cyclic peptides produced by the rice plant pathogen Ustilaginoidea virens, strongly inhibited the polymerization of porcine brain tubulin in vitro and depolymerized pre-formed microtubules. The IC50 values of polymerization inhibited by ustiloxins A-D were determined to be 0.7, 2.8, 4.4 and 6.6 microM, respectively, under the experimental conditions used, indicating that ustiloxin A is the most potent inhibitor of tubulin polymerization currently known. Ustiloxins A-C were found to inhibit the binding of radiolabelled rhizoxin to tubulin with inhibition constants (Ki) of 0.08, 0.13 and 0.23 microM, respectively, and also inhibited the binding of radiolabelled phomopsin A as strongly as rhizoxin. These results suggest that the binding site of ustiloxins is identical with that of rhizoxin.

Amino Acid Sequence↗
PubMed1995

Determination of the photoaffinity-labeled site on the ligand-binding domain of retinoic acid receptor alpha.

The ligand-binding domain of human retinoic acid receptor alpha (hRAR alpha) was photoaffinity-labeled with a fluorescent retinoid, ADAM-3, by the use of a recombinant fused protein constructed from a maltose-binding protein and the E/F-domain of hRAR alpha (MBP-RAR alpha/E), which was expressed in E. coli. The labeled site was identified as Arg-589 (this corresponds to amino acid residue 385 of hRAR alpha) or a residue in its vicinity.

Affinity Labels↗
PubMed1995

Possible involvement of retinoid-like cofactor in serum in hemin/protoporphyrin-IX-induced differentiation of human leukemia K562 cells.

Serum is generally added to media used for mammalian cell culture and for investigation of in vitro cell differentiation induction. Erythroid differentiation of human leukemia cell line K562 is induced by hemin or protoporphyrin IX in the presence of fetal bovine serum (FBS). Addition to the medium of retinoids enhanced the differentiation, and addition of retinoid antagonists suppressed the differentiation. Making the added FBS retinoid-free, i.e., treatment of the serum with charcoal, also reduced the efficiency of the cell differentiation induced by hemin or protoporphyrin IX. These facts suggest that retinoids or retinoid-like cofactor(s) in serum are necessary for hemin/protoporphyrin-IX-induced erythroid differentiation of K562 cells.

Cell Differentiation↗
PubMed1995

The complete amino acid sequences of two serine proteinase inhibitors from the fruiting bodies of a basidiomycete, Pleurotus ostreatus.

The complete amino acid sequences of two isomeric endogenous inhibitors, IA-1 and IA-2, both of which specifically inhibit an intracellular serine proteinase (proteinase A) purified from the fruiting bodies of a higher basidiomycete, Pleurotus ostreatus, were determined. Both inhibitors are acidic polypeptides with respective molecular masses of 8307 and 8244 Da, as determined by plasma desorption mass spectral analyses, and their N-terminal serine residue is blocked by acetylation. The fragments generated from the inhibitors by proteolytic and chemical cleavages were subjected to amino acid composition, sequence, and mass spectral analyses. The sequence and molecular mass information for the peptides established that the inhibitors both consisted of 76 amino acid residues and differed from each other in that aspartic acid and glutamic acid residues at residues 12 and 15 of IA-1 were replaced by glycine and aspartic acid in IA-2, respectively. The molecular masses of IA-1 and IA-2 were calculated to be 8309 and 8237, based on the sequence data. The action of carboxypeptidase Y on IA-1 resulted in a complete loss of the inhibitory activity along with successive release of glutamine and threonine from the C-terminus. Cyanogen bromide cleavage of Met38-Pro39 and Met41-Lys42 in IA-1 and hydroxylamine degradation of IA-2 completely abolished their inhibitory activity. These results suggest that the whole molecules of both inhibitors are essential to their inhibitory activities. Their structural resemblance to propeptides of subtilisin family proteinases revealed their mechanism of action.

Amino Acid Sequence↗
PubMed1995

Expression of renin in coagulating glands is regulated by testosterone.

BACKGROUND: The presence of extrarenal or local renin-angiotensin system (RAS) has been noted in several tissues, although its functions have not yet been clarified. Renin from the coagulating gland (CG) is the most recently discovered local RAS and is a significant subject for investigation because large amounts of both mRNA and proteins are detected in this organ. Recently, it has been reported that testosterone influences renin synthesis in several extrarenal tissues, although it has no effect on intrarenal renin. Therefore, it is possible that CG renin is also regulated by testosterone. METHODS: Forty-four male C57BL/6 mice, aged 3 wk to 6 mo, were used in studies on the ontogeny and androgen regulation of the RAS in the CG. The tissues were fixed with Bouin's solution and paraffin sections were stained with immunohistochemical methods using antirenin antiserum. In each immunostained section, the relative number of renin-containing cells in terminal portions of the CG were counted. RESULTS: Immunoreactivity for renin was first detected at 6 wk after birth. After that time, the number of renin-containing cells gradually increased throughout the experiment. In adults, several patterns of renin immunoreactivity were demonstrated in almost all epithelial cells of CGs, specifically; (1) basolateral granular reaction, (2) diffuse immunoreactivity throughout the cytoplasm, and (3) restricted nuclear reaction. Excretory products of some terminal lumina were also found to be positive for renin. At 10 days after castration, renin-containing cells in ductal termini were decreased and remained at low levels until at 4 wk after castration. After testosterone injection, numerical values of renin-containing cells were high at 1 wk and then decreased at 2-3 wk. CONCLUSION: It is suggested that CG renin of the mouse is expressed together with sexual maturation during development and that it depends on the testis, possibly the male sex hormone.

Animals↗
PubMed1995

Distribution of epithelioid cells in the wall of the chicken aorta and their functional role as chemoreceptors.

BACKGROUND: The ultrastructural characteristics of epithelioid cells in the wall of the chicken aorta have been studied by several investigators. Their characteristics were homologous to those of carotid body type I cells and are considered to be one of the peripheral chemoreceptors. However, there are few descriptions about their location, distribution, and how they react to chemical signals, nor have there been many reports about the localization of bioactive substances in the epithelioid cells. Therefore we designed this investigation to address these problems. METHODS: Wholemount immunohistochemistry using antiserotonin antiserum, scanning (SEM), and transmission (TEM) electron microscopy were used to observe the epithelioid cells and the lumen of the chicken aorta. The localizations of bioactive substances in the epithelioid cells were immunohistochemically investigated using 11 antisera. RESULTS: Epithelioid cells were dispersed in the wall of the aorta, forming a band approximately 1 mm in width, located 10 mm proximal to the confluence of the right and left ligamenta arteriosa. Serotonin, chromogranin, and neuron specific enolase immunoreactivities were detected in the epithelioid cells. SEM observations clearly demonstrated intraendothelial fenestrations, 1-3 microns in diameter, on the endothelial surface of the region of the band of epithelioid cells. TEM observations revealed that these fenestrations corresponded to endothelial gaps, directly beneath which epithelioid cells were sometimes located. CONCLUSIONS: The epithelioid cells are in direct access to the aortic lumen through endothelial fenestrations. Thus they may be able to perceive chemical signals from arterial blood directly.

Animals↗
PubMed1995

Investigation of EB virus and cytomegalovirus in rapidly progressive interstitial pneumonitis in polymyositis/dermatomyositis by in situ hybridization and polymerase chain reaction.

In polymyositis/dermatomyositis (PM/DM), a rapidly progressive interstitial pneumonitis (RPIP) which is a fatal complication of unknown etiology has received increasing attention. We have encountered 9 RPIP cases among 150 PM/DM cases in the past 10 years. To investigate the pathogenic role of viruses in RPIP, we examined lung specimens from patients with RPIP in PM/DM for the presence of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) using polymerase chain reaction (PCR) and in situ hybridization (ISH). We analyzed 21 specimens from RPIP in PM/DM (n = 9), collagen diseases (n = 6; 4 had interstitial lung disease), and controls (n = 6). EBV was frequently detected in RPIP (7/9 by PCR 3/9 by ISH), but was also detected in other collagen diseases of the lungs. In lung specimens from both patients with RPIP in PM/DM and those with collagen diseases, EBV was significantly detected (13/15 by PCR, 5/15 by ISH, P < 0.005) compared to controls (1/6 by PCR, 0/6 by ISH). CMV was detected by ISH in 2 RPIP patients but in none of he others, though by PCR CMV was detected equally in the three groups studied. These findings indicate that a direct involvement of EBV or CMV in RPIP of PM/DM is unlikely, although it is possible that an immune response to latent viruses or viral products in PM/DM may have a role in the pathogenesis of the RPIP.

Adult↗
PubMed1995

EDTA-insoluble, calcium-binding proteoglycan in bovine bone.

A calcium ion precipitable, trypsin-generated proteoglycan fragment has been isolated from the demineralized, EDTA-insoluble matrices of bone. The demineralized matrix was completely digested with trypsin, increasing concentrations of CaCl2 were added to the supernatant, and the resulting precipitates were analyzed. The amount of precipitate gradually increased with higher concentrations of calcium and was reversibly solubilized by EDTA. After molecular sieve and anion exchange chromatography, a proteoglycan-containing peak was obtained. Immunochemical analysis showed that this peak contained chondroitin 4-sulfate and possibly keratan sulfate. Amino acid analysis showed that this proteoglycan contained high amounts of aspartic acid/asparagine (Asx), serine (Ser), glutamic acid/glutamine (Glx), proline (Pro), and glycine (Gly); however, it contained little leucine (Leu) which suggests that it is not a member of the leucine-rich small proteoglycan family. In addition, significant amounts of phosphoserine (P-Ser) and hydroxyproline (Hyp) were identified in hydrolysates of this fraction. A single band (M(r) 59 kDa) was obtained on SDS-PAGE that stained with Stains-all but not with Coomassie Brilliant Blue R-250. If bone powder was trypsinized prior to demineralization, this proteoglycan-containing fraction was not liberated. Collectively, these results indicate that a proteoglycan occurs in the demineralized matrix that is precipitated with CaCl2 and is closely associated with both mineral and collagen matrices. Such a molecule might facilitate the structural network for the induction of mineralization in bone.

Amino Acids↗