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Biomedical subjects

K Goto

Publications and source records attributed to K Goto.

At least 451 records · Page 25Linked to original sources
PubMed1994

Cloning and expression of a cytoskeleton-associated diacylglycerol kinase that is dominantly expressed in cerebellum.

A third species of diacylglycerol kinase (EC 2.7.1.107) cDNA was cloned from a rat brain cDNA library. The isolated cDNA encoded a 788-amino acid, 88-kDa polypeptide. This isozyme shared 58% identity with the previously isolated rat 80-kDa and 90-kDa diacylglycerol kinases. EF hand motifs, cysteine-rich zinc finger-like sequences, and putative ATP-binding site were all conserved among these isozymes. The 88-kDa diacylglycerol kinase was expressed specifically in brain and localized predominantly in cerebellar Purkinje cells. This isozyme was associated equally with particulate and supernatant fractions in cDNA-transfected COS-7 cells and dominantly with the particulate fraction in the brain. After Triton X-100 extraction, this isozyme remained in the detergent-insoluble cytoskeletal fraction of the brain and transfected COS-7 cells.

Adenosine Triphosphate↗
PubMed1994

Endothelin-1 activates mitogen-activated protein kinases through two independent signalling pathways in rat astrocytes.

Northern blot analysis and displacement study revealed that the endothelin (ET) receptor functionally expressed in rat primary cultured astrocytes is the ETB receptor. Mitogen-activated protein kinases (MAP kinases) in the cells were activated by 10 nM ET-1, a dose that maximally stimulated phosphoinositide hydrolysis. This activation was potently inhibited by pretreatment of the cells with phorbol 12-myristate 13-acetate (PMA) which leads to protein kinase C (PKC) down-regulation and was slightly inhibited by pretreatment with pertussis toxin (PTX). Pretreatment of the cells with PMA plus PTX completely inhibited the ET-1-augmented MAP kinase activity. Activation of MAP kinases was also induced by 0.1 nM ET-1, which hardly stimulated phosphoinositide hydrolysis. This activation was fully inhibited by pretreatment with PTX but insensitive to pretreatment with PMA. ET-1-stimulated production of inositol phosphates was not affected by pretreatment with PTX. These results suggest that activation of MAP kinases secondary to stimulation of the ETB receptor with ET-1 in rat primary cultured astrocytes was mediated through two independent signalling pathways. PKC-dependent pathway and PTX-sensitive G protein-mediated pathway.

Animals↗
PubMed1994

The on-off mechanisms of the nicotinic acetylcholine receptor ion channel are performed by thermodynamic forces.

The active sites of nicotinic acetylcholine receptors are comparatively strong hydrophobic areas. When nicotinic acetylcholine receptor alpha-subunits bind with acetylcholines, the polar groups of nicotinic acetylcholine receptors and acetylcholines become more hydrophobic owing to repulsion of the bound water molecules, and the charged groups of nicotinic acetylcholine receptors and acetylcholines are neutralized. Thus, the large hydrophobic areas form at and around the binding sites of nicotinic acetylcholine receptors and acetylcholines. These exposed hydrophobic areas are unstable thermodynamically (oil in water), and thus sink toward the neighboring hydrophobic transmembrane segment (M2). The sinking of the acetylcholine-binding sites with the M2, which contains an ion channel, causes the negative residues of the top of the M2 to descend to the hydrophilic level of the immobile M2 of the other nicotinic acetylcholine receptor subunits. This pathway, which consists of hydrophilic part of the sunken alpha-subunits and the hydrophilic part of the immobile M2 of other subunits, allows for the easy passage of cations across the cellular membrane. The movements of the alpha-subunits sinking to the transmembrane area cause the release of acetylcholines from binding sites. The hydrophilic groups of acetylcholines (quaternary ammonium ion, etc) and nicotinic acetylcholine receptors (ionic groups of M2, etc) are unstable in hydrophobic conditions (water in oil), resulting in the binding site and the hydrophilic residues of M2 returning to the positions in the resting state.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Molecular cloning of low-Ca(2+)-sensitive-type non-muscle alpha-actinin.

We previously reported the purification and characterization of a novel non-muscle alpha-actinin from chicken lung [Imamura, M. & Masaki, T, (1992) J. Biol. Chem. 267, 25927-25933]. The Ca2+ sensitivity of the lung alpha-actinin for the interaction with polymerized actin (F-actin) was much lower than those of the other reported non-muscle alpha-actinins. Here, we isolated a cDNA clone encoding the novel alpha-actinin by screening a chicken lung lambda g11 cDNA library with antibody specific for the low-Ca(2+)-sensitive alpha-actinin. The deduced amino acid sequence of the lung alpha-actinin showed 76%, 82% and 83% identity to those of chicken skeletal muscle, smooth-muscle and fibroblast-type alpha-actinin, respectively. Marked difference in the structure between the lung-type and the other alpha-actinins was found in the extreme NH2-terminal and in the COOH-terminal half; in the third and fourth regions of four spectrin-like repeats, and in two Ca(2+)-binding EF-hand consensus regions. The NH2-terminal-side EF-hand contained a notable defect in one of the five oxygen-containing amino acid side chains involved in chelating Ca2+, suggesting that the lower Ca2+ sensitivity of the lung alpha-actinin is ascribable to this defect. Northern blot analysis showed that the expression pattern of lung-type alpha-actinin mRNA in various non-muscle tissues differed from that of the other known non-muscle-type (fibroblast-type) alpha-actinin. The present results clearly demonstrate the existence of two structurally and functionally different types of non-muscle alpha-actinin; high-Ca(2+)-sensitive-type (NM1) and low-Ca(2+)-sensitive-type (NM2) alpha-actinin.

Actinin↗
PubMed1994

Function and regulation of the Arabidopsis floral homeotic gene PISTILLATA.

Mutations in the PISTILLATA (PI) gene of Arabidopsis thaliana cause homeotic conversion of petals to sepals and of stamens to carpels. It is thus classed as a B function floral homeotic gene and acts together with the product of the other known B function gene, APETALA3 (AP3). We have cloned PI and determined the time and places of its expression in developing flowers. Surprisingly, the initial patterns of PI and AP3 expression are different. By positive regulatory interactions between PI and AP3, later expression patterns are coincident or nearly coincident. The pattern of PI expression also depends on the activity of the floral development genes APETALA2 and SUPERMAN and on the activity of PI itself. The PI and APETALA3 proteins specifically associate in solution and so may act together in regulating PI and other genes.

Amino Acid Sequence↗
PubMed1994

Activin A stimulates mitogenesis in Swiss 3T3 fibroblasts without activation of mitogen-activated protein kinases.

Activin A stimulated DNA synthesis and transient c-fos expression in quiescent Swiss 3T3 fibroblasts. The activin A-induced DNA synthesis was dose-dependent with a half-maximal effect obtained at 0.3 nM. The maximal response obtained at 10 nM was comparable with that induced by 5 ng/ml basic fibroblast growth factor. Swiss 3T3 fibroblasts expressed abundant high affinity binding sites for 125I-labeled activin A with a Kd value of 0.63 nM and the number of binding sites at 24,000/cell. Northern blot analysis revealed that Swiss 3T3 fibroblasts express a high level of type II activin receptor mRNA. In an attempt to elucidate the mechanism of mitogenic action of activin A, we examined the effect of activin A on mitogen-activated protein kinase activation. Unexpectedly, however, activin A did not induce kinase activation under conditions in which basic fibroblast growth factor and endothelin-1 at similar or even less potent mitogenic concentrations did. Furthermore, activin A did not induce phosphorylation of the Erk2 species of mitogen-activated protein kinase. These observations strongly suggest that the activation of mitogen-activated protein kinase is not a necessary step for activin A-induced DNA synthesis in Swiss 3T3 fibroblasts.

3T3 Cells↗
PubMed1994

Mechanisms of hypotension in iminoctadine poisoning: pharmacological analysis in rats.

Iminoctadine, a fungicide used widely in fruit culture, causes hypotension in human acute oral poisoning. In an attempt to elucidate this mechanism, we investigated the effects of iminoctadine on the cardiovascular system of rats. In anesthetized rats, intravenously administered iminoctadine produced hypotension and tachycardia. In isolated right atria beating spontaneously in Krebs-Ringer's solution, iminoctadine produced an increase in heart rate. It also produced a positive inotropic response in electrically driven left atria. These responses were partially diminished by atenolol, a beta 1-adrenoceptor antagonist, and also partially diminished to a similar degree in atria of reserpinized rats. Therefore, the positive inotropic and chronotropic effects of iminoctadine were partially mediated via the release of norepinephrine from sympathetic nerve terminals. In aortic ring segments, iminoctadine caused a rightward shift of the concentration-contractile response curve for phenylephrine but did not affect those for prostaglandin F2 alpha or KCl. Iminoctadine produced a potent vasodilation in aortic segments precontracted with phenylephrine. Removal of the aortic endothelium produced a rightward shift of the concentration-response curve for iminoctadine. When the aortic ring preparations were precontracted with prostaglandin F2 alpha or KCl, iminoctadine produced only slight vasodilation. Therefore, the vasodilation caused by iminoctadine is due mostly to its alpha 1-adrenoceptor antagonizing action, and partly to endothelium-dependent mechanisms our data suggest that the hypotension induced by iminoctadine is due to its vasodilator effects.

Animals↗
PubMed1994

Human endothelin receptor ETB. Amino acid sequence requirements for super stable complex formation with its ligand.

ETB type endothelin receptor (ETBR) forms a stable complex with its ligand endothelin-1 (ET-1). The ligand-receptor complex can survive in the presence of 2% SDS and migrate in SDS-polyacrylamide gel electrophoresis at reduced temperature. This is not the case for the ETA type endothelin receptor (ETAR). Most of ETBR from various animals, except rat, can form such a stable complex. Examination of stability in the ligand-receptor complex which was formed by chimeric receptors constructed from human ETBR and rat ETBR demonstrated that the region containing 29 amino acids in the N-terminal extracellular domain is responsible for the formation of such a stable complex. Site-directed mutagenesis focused on this particular region revealed that Asp75 and Pro93 are involved in the formation of the stable complex. This unique observation contributes to the elucidation of the structure of the stable ETBR.ET-1 complex at the molecular level.

Amino Acid Sequence↗
PubMed1994

Circulatory failure caused by a fungicide containing iminoctadine and a surfactant: a pharmacological analysis in rats.

The fungicide Befran (BFR), containing iminoctadine as an active ingredient and polyoxyethylene alkylether (POEAE) as a surfactant, has been known to cause circulatory failure in human acute oral poisoning. We investigated separately the effects of iminoctadine, POEAE, and BFR on heart rate and blood pressure of rats and also on isolated atria and aortas. In isolated rat atria, iminoctadine produced positive chronotropic and inotropic responses. In contrast, POEAE produced negative chronotropic and inotropic responses. BFR produced no effects at low concentrations, but significant negative chronotropic and inotropic responses at high concentrations. In isolated rat aortas, iminoctadine produced remarkable vasodilative responses, but POEAE produced vasoconstrictive responses. BFR produced both vasodilative and vasoconstrictive responses. When intravenously administered to anesthetized rats, iminoctadine produced hypotension and tachycardia in a dose-dependent manner. POEAE produced significant hypotension and slight bradycardia. BFR, at low doses, produced hypotension without elevation of heart rate. At high doses, it produced significant hypotension and tachycardia. From these results, it can be concluded that severe hypotension induced by BFR is due mainly to the vasodilative effect of iminoctadine and partly to the cardio-suppressive effect of POEAE.

Animals↗
PubMed1994

Vasodilator innervation of small cerebral arteries of guinea pigs.

The neuronal influence on the resistance of cerebral arteries was analyzed in middle cerebral arteries of guinea pigs. Calcitonin gene-related peptide- and vasoactive intestinal peptide-immunoreactive nerves and NADPH-diaphorase-positive nerves were present in the distal portion of the middle cerebral artery. Isolated middle cerebral arteries were cannulated and perfused at a constant flow rate (1 ml/min) and the perfusion pressure was monitored. Prostaglandin F2 alpha (PGF2 alpha) and K+ (50 mM) elicited a sustained increase of the perfusion pressure (vasoconstriction), while noradrenaline and 5-hydroxytryptamine caused only a slight constriction. Electrical field stimulation (FS) at 8 Hz did not elicit a contractile response. In tissues precontracted with PGF2 alpha, FS induced a tetrodotoxin-sensitive vasodilator response. Endothelium-denudation and removal of the effect of sensory nerves by capsaicin-treatment did not affect the FS-induced vasodilation. In contrast, nitro-L-arginine, an inhibitor of NO formation, attenuated the FS-induced vasodilatation. These results show that the resistance of the cerebral vessels of guinea pigs is under the influence of vasodilator nerves and that the neurogenic vasodilator mechanism involves NO synthesis.

Animals↗
PubMed1994

Localization of mRNAs for calpain and calpastatin in the adult rat brain by in situ hybridization histochemistry.

The detailed localization of mRNAs for calpain II and calpastatin was examined in adult rat brain by in situ hybridization histochemistry. The expression patterns of the two mRNAs were similar to each other throughout the brain in terms of relative expression intensity, and almost all neurons expressed both mRNAs more or less. Among them, neurons in cranial nerve nuclei and some others in the brain stem expressed at relatively high levels, suggesting the high involvement of the non-lysosomal proteolytic system in the function of these neurons. On the other hand, the expression levels of the two mRNAs in non-neuronal cells including glia were basically low with the choroid plexuses expressing calpastatin mRNA relatively highly.

Animals↗
PubMed1994

Immunohistochemical analysis of perforin and granzyme A in inflammatory myopathies.

Perforin (PF) and granzyme A (GA) are candidates suspected of being cytolytic proteins of the granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. We analysed PF and GA in muscles from patients with inflammatory myopathies. Five cases of polymyositis (PM), two cases of inclusion body myositis (IBM), and five cases of dermatomyositis (DM) were studied immunohistochemically using anti-PF and GA antibodies raised against each synthetic peptide of human PF and mouse GA, together with a panel of monoclonal antibodies reactive for lymphocyte subsets. In PM and IBM, PF positive cells were colocalized with GA positive cells and occasionally invaded into the non-necrotic muscle fibres. The percentage of PF positive cells among the endomysial CD8 positive cell population was 9.9% (PM) and 12.5% (IBM), and the majority of the endomysial CD8 positive cells were alpha/beta T cells. In contrast, in DM, both PF and GA positive cells were very few in all cases. Only few inflammatory cells were CD16+ or CD57+ NK cells among these diseases. Our results suggest that PF and GA are secreted mainly from alpha/beta T cells, and may play a key role in muscle fibre damage in at least some PM and IBM, but not in DM.

Aged↗
PubMed1994

Metallothionein expression is correlated with cisplatin resistance in transitional cell carcinoma of the urinary tract.

Metallothioneins (MTs) are small cysteine-rich, metal-binding proteins involved in resistance to heavy-metal toxicity, and are known to bind cisplatin. Several experiments suggest possible involvement of MT in cellular resistance to cisplatin. To investigate the relationship between MT expression and cisplatin resistance in urinary tract transitional cell carcinoma (TCC), immunohistochemical staining for MT was performed in 31 untreated TCCs of the urinary tract. The results were compared with the sensitivity of the tumors to cisplatin as assessed by the microtiter succinate dehydrogenase inhibition (mSDI) test. Variable MT expression was observed in all 31 TCCs, but there was no specific correlation between histopathological parameters and MT expression. Fourteen (87.5%) of the 16 TCCs with less than 10% of their tumor cells positive for MT were sensitive to cisplatin. On the other hand, 6 (75.0%) of the 8 TCCs with MT expression by more than 30% of their tumor cells were resistant to cisplatin, and there was a significant correlation between MT expression and cisplatin resistance (p < 0.01). These results suggest the possible involvement of MT in the intrinsic cisplatin resistance of urinary tract TCC and that immunohistochemical investigation of MT may be useful for predicting the response of these tumors to cisplatin therapy.

Adult↗
PubMed1994

Expression of DNA methyltransferase gene in mature and immature neurons as well as proliferating cells in mice.

A major role of DNA-methyltransferase (MTase) is thought to be maintaining the DNA methylation profile through DNA replication. However, previous surveys of mRNA distribution in different tissues by Northern-blot analysis have shown unexpectedly high levels of expression of DNA-MTase mRNA in adult mouse brain, which consists mostly of slowly proliferating glial and nonproliferating neuronal cells. In order to identify cells expressing the gene in the brain, we performed an in situ hybridization analysis of mature brain as well as whole embryos of different ages. In addition to various embryonic tissues with active cell proliferation such as the ventricular neurogenic layer, hair follicle epithelia, thymus and epithelia of the base of intestinal villi, almost all mature neurons in brain of adult and even aged mice expressed DNA-MTase mRNA at substantial levels. No significant expression of the gene was detected in the white matter. These findings suggest some neuron-specific biological function of DNA methylation, unrelated to DNA replication.

Animals↗
PubMed1994

Dynamic changes in mRNA expression of neutrophils during the course of acute inflammation in rabbits.

To examine RNA/protein synthesis of neutrophils and related dynamic changes during the inflammatory process, we investigated mRNA expressions in neutrophils, by RNA blot hybridization analyses using 12 different rabbit gene probes. We first selected five candidate genes encoding inflammation-related proteins, i.e. tumor necrosis factor (TNF-alpha) IL-1 alpha, IL-1 beta, neutrophil activating peptide-1/IL-8 (NAP-1/IL-8) and monocyte chemoattractant protein (MCP)-1. We further selected several genes on basis of the results from gene subtraction between cDNA libraries from neutrophils at an early (5 h) and at a late (24 h) stage of casein-induced acute peritonitis in rabbits, i.e. immune activation gene-2 (Act-2), migration inhibitory factor-related protein-8 (MRP-8), MRP-14, gamma-actin, and formyl-methionyl-leucyl-phenylalanine receptor (fMLP-R), and ferritin light (L) chain. In addition to these genes we used ferritin heavy (H) chain gene, another component of the ferritin molecule. We examined mRNA expressions by cytoplasmic slot blot analysis of the above 12 genes in neutrophils obtained from blood and from various stages of casein-induced inflammation in rabbits. The observed patterns of mRNA expression kinetics were classified into three. Pattern 1: mRNAs of MRP-8, MRP-14, and gamma-actin were constitutively expressed in blood neutrophils, and increased rapidly after emigration into inflammatory sites. Pattern 2: mRNAs of IL-1 beta, NAP-1/IL-8, Act-2, and fMLP-R were undetectable in blood neutrophils, and were induced rapidly after the onset of inflammation. Pattern 3 mRNAs of ferritin L and H chain were induced slowly, and increased with progression of the inflammatory process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Plasma alpha-1-antiproteinase from the Mongolian gerbil, Meriones unguiculatus: isolation, partial characterization, sequencing of cDNA, and implications for molecular evolution.

alpha-1-Antiproteinase (also called alpha-1-proteinase inhibitor or alpha-1-antitrypsin) with a molecular mass of 56 kDa was purified from plasma of the Mongolian gerbil, Meriones unguiculatus, to apparent homogeneity. It inhibited trypsin, chymotrypsin, elastase, and plasmin, but not kallikrein or thrombin. Eight cDNA clones coding for this protein were isolated from a liver cDNA library and sequenced. They contained the same coding regions consisting of a 24-residue signal peptide and a 382-residue mature protein. The reactive site sequence (P3-P3) was Val-Pro-Met-Ser-Ile-Pro, characteristic of alpha-1-antiproteinase of orthodox type [Suzuki, Y. et al. (1991) J. Biol. Chem. 266, 928-932]. A molecular phylogenetic tree of 11 orthologous inhibitors, constructed on the basis of the synonymous substitution rate, shows (i) that the reactive site region is highly conserved as compared to the other part of the molecule, which contrasts with the generally accepted view that the reactive site region of serpins is strongly hypervariable, and (ii) that the myomorphs (gerbil, rat, and two species of mouse, i.e. Mus domesticus and Mus caroli) and the caviomorph (guinea pig) fail to consist of a monophyletic order, which also contradicts the traditional taxonomy based on the morphology. In the present tree, the guinea pig joins the lagomorph (rabbit), and is rather widely separated from the myomorph branch. The result, however, supports the recent hypothesis based on the molecular evolution of several other proteins that the guinea pig does not belong to the same order as the myomorph, and the caviomorphs should be elevated in taxonomic rank and conferred an ordinal status distinct from the rodents.

Amino Acid Sequence↗
PubMed1994

Investigation of melena and hematochezia as the chief complaint of gastrointestinal bleeding in pediatric surgical patients.

The causes of melena or hematochezia in 48 pediatric patients were examined. Malrotation with volvulus was an important cause of hemorrhage during the newborn period, and intussusception was very typical in patients aged from 1 month to 1 year. Polyps of the rectum and colon were the most common causes of melena or hematochezia in patients older than 1 year. No cause of melena or hematochezia could be identified in 11 children. Ten patients have remained in good health with no further episodes of melena or hematochezia. Localized multiple polyps of the rectum with focal carcinoma were detected in only one patient. In general, although no further investigation is required after detection of the cause of bleeding and its successful treatment, it should be kept in mind that gastrointestinal malignancy can occur in children.

Adolescent↗