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Biomedical subjects

Y Kimura

Publications and source records attributed to Y Kimura.

At least 19 recordsLinked to original sources
PubMed1992

Enhanced acetylcholine secretion in neuroblastoma x glioma hybrid NG108-15 cells transfected with rat choline acetyltransferase cDNA.

Neuroblastoma x glioma hybrid NG108-15 cells and mouse neuroblastoma N18TG-2 and N1E-115 cells were transiently transfected with the sense cDNA coding for rat choline acetyltransferase (ChAT). All transfected cell lines showed a high level of ChAT activity. ACh secretion was monitored by recording miniature end-plate potentials (MEPPs) in striated muscle cells that had been co-cultured with transfected cells. The number of muscle cells with synaptic responses and the MEPP frequency were higher in co-culture with transfected NG108-15 cells than with control or mock cells. No synaptic response was detected in muscle cells co-cultured with transfected N18TG-2 or N1E-115 cells. The results show that ACh secretion into the synaptic cleft was enhanced due to ChAT overexpression in NG108-15 hybrid cells but not in neuroblastoma cells.

Acetylcholine↗
PubMed1992

Genetically engineered rice resistant to rice stripe virus, an insect-transmitted virus.

The coat protein (CP) gene of rice stripe virus was introduced into two japonica varieties of rice by electroporation of protoplasts. The resultant transgenic plants expressed the CP at high levels (up to 0.5% of total soluble protein) and exhibited a significant level of resistance to virus infection. Plants derived from selfed progeny of the primary transformants also expressed the CP and showed viral resistance, indicating stable transmission of the CP gene and the trait of resistance to the next generation. Moreover, the virally encoded strip disease-specific protein was not detected in transgenic plants expressing CP 8 weeks after inoculation, indicating protection before viral multiplication. These studies demonstrated that CP-mediated resistance to virus infection can be extended to cereals and to the viruses transmitted by an insect vector (planthopper).

Base Sequence↗
PubMed1992

Anthranilic acid release in adenosine-inhibited cultures of Saccharomyces cerevisiae and its inhibition by thiamin.

Adenosine, at 1 mM concentrations or above, was found to have a fungistatic effect on Saccharomyces cerevisiae. A substance with amethyst fluorescence was detected in the medium of adenosine-inhibited cultures of S. cerevisiae. This compound was isolated and physicochemically identified as anthranilic acid. Both the inhibition of growth and release of anthranilic acid induced by adenosine were abrogated by thiamin or by the pyrimidine portion of thiamin, 2-methyl-4-amino-5-hdroxymethyl-pyrimidine (hydroxymethyl-pyrimidine); the latter was found to restore intracellular thiamin content that had been reduced by adenosine. It was demonstrated that effects of thiamin and hydroxymethylpyrimidine on S. cerevisiae cultured with adenosine resulted from their inhibition of adenosine uptake by growing yeast cells.

Adenosine↗
PubMed1992

Purification of serine hydroxymethyltransferase from Bacillus stearothermophilus with ion-exchange high-performance liquid chromatography.

The gene of serine hydroxymethyltransferase (SHMT) of a thermophilic bacterium Bacillus stearothermophilus was expressed in Escherichia coli, and SHMT was successfully purified from the crude extract of E. coli in two steps while maintaining the enzymatic activity. The purification steps involved ammonium sulphate precipitation followed by high-performance liquid chromatographic separation using the anion-exchange column Fractogel EMD DEAE-650(S). In addition to the DEAE column, three other types of anion- and cation-exchange columns were also studied for their ability to separate SHMT, and the performance of the four columns were compared.

Ammonium Sulfate↗
PubMed1992

Molecular mechanism of regulation of Ca2+ pump ATPase by phospholamban in cardiac sarcoplasmic reticulum. Effects of synthetic phospholamban peptides on Ca2+ pump ATPase.

The molecular mechanism of the regulation of Ca2+ pump ATPase by phospholamban in cardiac sarcoplasmic reticulum was examined using synthetic peptides of phospholamban and purified Ca2+ pump ATPase from cardiac sarcoplasmic reticulum. The phospholamban monomer of 52 amino acid residues contains two distinct domains, the cytoplasmic (amino acids 1-30) and the transmembrane (amino acids 31-52) domains. The peptide corresponding to the amino acids 1-31 of phospholamban (PLN 1-31) decreased the Vmax of the Ca(2+)-dependent ATPase activity in dose-dependent manner, while it had no effect on the affinity of the ATPase for Ca2+ (KCa). On the other hand, the peptide corresponding to the amino acids 28-47 of phospholamban (PLN 28-47) increased the KCa from 0.52 to 1.33 microM without significant change in the Vmax value when reconstituted into vesicles with the ATPase. Essentially the same results as PLN 28-47 were obtained with the peptide corresponding to the amino acids 8-47 of phospholamban (PLN 8-47). The inhibitory effects of PLN 1-31 and PLN 8-47 on the ATPase were reversed by cAMP-dependent phosphorylation of the peptides (Ser16). These results indicate that phospholamban suppresses Ca2+ pump ATPase at two different sites, the cytoplasmic domain for Vmax and the transmembrane domain for KCa, and that cAMP-dependent phosphorylation de-suppresses these inhibitory effects on the ATPase.

Amino Acid Sequence↗
PubMed1992

Pharmacokinetic analysis of maprotiline and its demethylated metabolite in serum and brain of rats after acute and chronic oral administration of maprotiline.

Compartmental model analysis by simultaneous curve fitting was used to ascertain the pharmacokinetic relationship between maprotiline (MAP) and its demethylated metabolite desmethylmaprotiline (DMAP) in the serum and brain of rats after single or multiple oral administrations of MAP. The extent of bioavailability and the fraction metabolized to DMAP after acute oral administration were 0.202 and 0.065, respectively, indicating first-pass metabolism of MAP. Although the estimated transfer rate constants to and from the brain (k(in) and k(out)) of MAP were higher than those of DMAP, the k(in):k(out) ratio for MAP was similar to that for DMAP. These findings indicate the equivalent ability of MAP and DMAP to penetrate into the brain after acute oral administration. The estimated values of bioavailability and fraction metabolized to DMAP increased 2.6 and 1.7 times, respectively, after chronic administration of MAP. These findings are attributable to inhibited distribution in tissue. The k(in) and k(out) values of MAP decreased, whereas those of DMAP showed no marked change. Therefore, the k(in):k(out) ratio for MAP decreased, whereas that for DMAP did not change. These results suggest that the permeability of MAP into the brain might be affected and that of DMAP is not modified by chronic administration of MAP.

Administration, Oral↗
PubMed1992

In vitro and in vivo effects of diethylene triamine penta-acetic acid on the distribution of indium-111 monoclonal antibody metabolism.

The effects of diethylene triamine penta-acetic acid (DTPA) on indium-111 monoclonal antibody (MoAb) metabolism were examined. Sequential analysis of 111In-MoAb incubated in serum at 37 degrees C by high performance liquid chromatography (HPLC) and electrophoresis revealed that the radioactivity gradually moved from the MoAb to a 70-90 kDa molecular weight fraction. DTPA inhibited the transchelation of 111In to this fraction. It also decreased 111In uptake by isolated rat hepatocytes but did not remove 111In incorporated in hepatocytes. The daily in vivo administration of DTPA (0.5-2.0 mg/mouse daily) to athymic mice after 111In-MoAb injection significantly reduced the 111In uptake in the liver and kidney. The tumour uptake was decreased somewhat but not significantly. The serum radioactivity in the 70-90 kDa fraction was also decreased. Scintigraphic examination demonstrated a decreased liver uptake in the DTPA-treated group of mice. Our results show that 111In released from the DTPA-MoAb conjugate in serum binds to molecules of 70-90 kDa and that DTPA decreases the 111In uptake in this fraction, which induces a decrease of 111In accumulation in normal tissues.

Animals↗
PubMed1992

Polymorphism of coagulation factor XIII B subunit: further occurrence of FXIIIB*15 in Japanese and phenotyping in bloodstains.

The polymorphism of FXIIIB was investigated in 555 unrelated Japanese individuals using isoelectric focusing and immunoblotting. Five common phenotypes and a rare variant type FXIIIB 15-3 were observed. The allele frequencies were FXIIIB*1 = 0.3063, FXIIIB*2 = 0.0162, FXIIIB*3 = 0.6766 and FXIIIB*15 = 0.0009. Phenotyping was also possible from bloodstains stored at 37 degrees C for up to 4 months and from bloodstains stored at room temperature and at 4 degrees C for over 6 months. The FXIIIB system can provide a new powerful genetic marker for the medicolegal grouping of bloodstains.

Alleles↗
PubMed1992

Moderation of myocardial ischemia reperfusion injury by calcium channel and calmodulin receptor inhibition.

Intracellular Ca2+ accumulation is implicated in the pathogenesis of myocardial reperfusion injury. To study approaches designed to modify Ca2+ uptake during coronary revascularization after acute infarction, a pig heart surgical infarct model (left anterior descending artery occlusion for 60 min) was subjected to 60 min hypothermic potassium cardioplegic arrest, followed by 60 min of global reperfusion. Four groups of six hearts each were studied in a randomized manner, i.e., cardioplegia alone (control), cardioplegia + 10 microM diltiazem (Ca2+ slow channel blocker), cardioplegia + 10 microM trifluoperazine (TFP), (a Ca(2+)-calmodulin antagonist), and cardioplegia+diltiazem (10 microM) + TFP (10 microM). Left ventricular contractility (global and segmental), metabolism (coronary blood flow and O2 consumption), and creatine kinase generation were measured during reperfusion. Both the Ca2+ channel blocker, diltiazem, and the calmodulin antagonist, TFP, improved myocardial global and regional function as well as myocardial metabolism. While diltiazem better restored global and regional contractility, trifluoperazine had a greater effect on coronary blood flow and myocardial oxygen consumption. Enzyme release and lipid peroxidation were equally moderated by both drugs. From this study it can be concluded that Ca2+ influx does play a role in ischemic and reperfusion injury. The mechanisms of its effect are complex, but can be successfully antagonized by Ca2+ blockers as well as by calmodulin antagonists, with improved myocardial preservation.

Animals↗
PubMed1992

Concurrent changes in sinusoidal expression of laminin and affinity of hepatocytes to laminin during rat liver regeneration.

Distribution of fibronectin, laminin, and collagens type I, III, IV, and V in the lobular regions of regenerating rat liver was studied by indirect immunofluorescence. Little or no laminin was detected in sham-operated controls throughout the experimental period, while it was detected in sinusoids of regenerating liver as early as 6 h after partial hepatectomy (PH). After reaching a maximum at 24 h, it decreased and was barely detectable 6 days after PH. Changes in the other extracellular matrix (ECM) proteins were evident 3 days after PH, but not earlier than 24 h. Hepatocytes isolated from regenerating rat livers were tested in a short term assay for attachment to the substrates coated with the ECM proteins. The attachment of hepatocytes to laminin substrates increased 12 h after PH, reached a maximum at 24 h, and decreased to the control level 6 days after PH, while that of the control remained constant. The attachment to fibronectin substrates was not different between regenerating livers and controls at any time point. The attachment to collagen did not change earlier than 24 h after PH, but increased slightly 3 days after PH. Primary rat hepatocytes cultured on the substrates coated with the ECM proteins were determined for replicative DNA synthesis in response to epidermal growth factor. Both in normal liver and in regenerating liver 24 h after PH, laminin was one of the most effective substrates in supporting the responsiveness of hepatocytes to the growth stimulus. Taken together, these results suggest the importance of hepatocyte-laminin interaction during the early stage of liver regeneration possibly in growth stimulation of hepatocytes and/or maintenance of hepatocyte-specific functions.

Animals↗
PubMed1992

Depression of plasma gelsolin level during acute liver injury.

Human plasma contains two actin-binding proteins, plasma gelsolin and vitamin D-binding protein. These proteins are considered to play an important role in the disposition of actin derived from injured tissue. To evaluate this actin-scavenger system, gelsolin concentrations were measured in serial plasma samples obtained from patients with acute liver injury using an enzyme-linked immunosorbent assay. Plasma gelsolin levels in 43 healthy persons were 226 +/- 52 micrograms/mL. They were markedly reduced to 80 +/- 40 micrograms/mL in 14 patients with an early stage of acute hepatitis and returned to normal levels of 232 +/- 38 micrograms/mL as the disease resolved. Moreover, they showed a significant negative correlation with serum aminotransferase and bilirubin levels. In 7 patients with hepatocellular carcinoma, plasma gelsolin levels rapidly decreased from 182 +/- 42 to 87 +/- 41 micrograms/mL after transcatheter arterial embolization therapy. Because plasma gelsolin is not a hepatic protein, the decreased levels are considered to depend exclusively on the extent of actin leakage from the injured liver.

Actins↗
PubMed1992

Chronic clonidine treatment and its termination: effects on penile erection and ejaculation in the dog.

The effects of chronic administration (4 weeks) of the alpha-2 adrenoceptor agonist clonidine (CL) and its termination on penile erection and ejaculation were investigated in male dogs. Penile erection and ejaculation were elicited by manual penile stimulation (for 5 min). CL (10 micrograms/kg/hr, s.c.) was delivered via osmotic minipump (Alza, 2ML-4). 3 or 7 days after the minipump implantation, CL caused a significant decrease in the amount of ejaculate produced by the genital stimulation without affecting the erectile potency. Ejaculatory ability returned to pretreatment levels despite continued CL administration, becoming evident in tests 14 days after initiation of treatment. Further, chronic CL (23 days) antagonized the inhibitory effects of acute administration of CL (0.05 mg/kg, i.p.). These data indicate tolerance to continued delivery of low doses as well as to acute administration of a higher dose. In the acute drug experiments, the ejaculatory inhibition elicited by CL (0.05 mg/kg, i.p.) was completely antagonized by pretreatment with yohimbine (0.05 and 0.10 mg/kg, i.p.), an alpha-2 adrenoceptor antagonist, but not with naloxone (1.0 mg/kg, i.p.), an opioid receptor antagonist. Furthermore, DG-5128 (1.0 and 2.0 mg/kg, i.p.), a selective alpha-2 adrenoceptor antagonist that poorly penetrates the blood-brain barrier, failed to antagonize the CL-induced ejaculatory inhibition. This study suggests that functional alterations in the central alpha-2 adrenoceptor mechanism may be related to the changes in the ejaculatory capacity during chronic treatment with CL.

Adrenergic alpha-Antagonists↗
PubMed1992

Structural determination of gangliosides that bind to influenza A, B, and C viruses by an improved binding assay: strain-specific receptor epitopes in sialo-sugar chains.

An improved binding assay for detection of ganglioside receptors for influenza A, B, and C viruses was developed. In this system, the virions bound to gangliosides that were developed on a silica gel thin-layer plate were detected by mouse monoclonal antibody against viral hemagglutinin and peroxidase-conjugated anti-mouse immunoglobin. No hydrolysis of the gangliosides by viral receptor-destroying enzyme was detected in the present condition. The reactivity of the viruses to gangliosides depended on the amount of developed gangliosides (10 pmols-10 nmols), the molecular species of sialic acid, and their sugar sequences. Human influenza A (PR/8/34), B (Lee/40), and C (Ann Arbor/1/50) viruses bound different receptor epitopes of sialo-sugar chains of gangliosides. The A/PR/8 virus bound most effectively to Neu5Ac-containing lacto-series gangliosides carrying type I and type II sugar chains, followed by ganglio-series and hematoside-series gangliosides. The A/PR/8 virus weakly bound to Neu5Ac alpha 2,6lactotetraosylceramide [IV6(Neu5Ac)Lc4Cer] and Neu5Ac alpha 2,6paragloboside [IV6(Neu5Ac)nLc4Cer] carrying Neu5Ac alpha 2,6Gal sequence, although their Neu5Ac alpha 2,3Gal derivatives were the most potent gangliosides tested. B/Lee/40 bound restrictively to IV6(Neu5Ac)Lc4Cer and IV6(Neu5Ac)nLc4Cer, which carry Neu5Ac alpha 2,6Gal sequence, and type I and type II lacto-series sugar chain, respectively. C/Ann Arbor/1/50 reacted only with 9-O-Ac-Neu5Ac-carrying sugar chains in all the gangliosides tested. This method also allowed the microanalysis of receptor gangliosides of unknown samples. ESK cells, sensitive to the influenza A viruses infection, expressed several kinds of receptor active gangliosides, while those from ESK-R cells, resistant to the virus infection, were undetectable.

Binding Sites↗
PubMed1992

Argininosuccinate synthetase gene expression in leukemias: potential diagnostic marker for blastic crisis of chronic myelocytic leukemia.

Argininosuccinate synthetase (ASS) activity is hardly detected in human lymphocytes. In this study, we examined the ASS gene expression of various leukemia cells by a polymerase-chain-reaction method. We demonstrate here that (a) acute lymphocytic and acute myelocytic leukemia cells exhibit the highly elevated expression of the ASS gene and (b) chronic myelocytic leukemia (CML) in blastic crisis also exhibits the increase of ASS gene expression while CML in chronic phase, chronic lymphocytic leukemia and adult T leukemia cells show the similar level to that of normal lymphocytes. These results suggest that the ASS gene expression is of value as a diagnostic marker of acute type leukemia, particularly for blastic crisis of CML.

Adult↗
PubMed1992

Dissection of bradykinin-evoked responses by buffering intracellular Ca2+ in neuroblastoma x glioma hybrid NG108-15 cells.

Signal transduction pathways from bradykinin (BK) receptors were investigated in NG108-15 neuroblastoma x glioma hybrid cells by buffering the intracellular calcium (Ca2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a Ca2+ chelator. BK increased inositol-1,4,5-trisphosphate (Ins(1, 4,5)P3) formation at the same rate in the control and in BAPTA-acetoxy methyl ester (AM)-treated NG108-15 cells. However, a transient increase of intracellular Ca2+ concentrations in response to BK was significantly suppressed in Ca(2+)-buffered hybrid cells. Accordingly the BK-induced outward current was inhibited in BAPTA-AM-treated hybrid cells, while the subsequent inward current associated with a fall in membrane conductance was apparently increased. The initial phase of acetylcholine release from NG108-15 cells in response to BK was markedly inhibited in BAPTA-AM-treated coculture dishes when detected as miniature end-plate potentials of myotubes, though the late phase of acetylcholine secretion was observed. These results indicate that BK induces two distinct responses in NG108-15 cells: Ins(1,4,5)P3-dependent intracellular Ca2+ rise-sensitive and -insensitive components.

Animals↗
PubMed1992

A method for observing cross-sectional views of biomembranes.

Cross-sectional views of intact biomembranes and synthetic lipid bilayer membranes were observed by electron cryomicroscopy using spontaneous orientation of disk-shaped membranes; purple membrane, thylakoid membrane, synthetic phospholipid membrane and a microcrystalline sheet made of Er-binding polypeptide were observed. The membranes were observed fully hydrated, embedded in vitreous ice, and their self-orientation was most probably caused by repulsion between their hydrophobic edges and their hydrophilic environment which forced their edges to be exposed to the air-water interface. The cross-sectional profiles of the native biomembranes were asymmetric and characteristic, whilst those of the synthetic membranes were symmetric and predictable by a simple model. Simple Fourier analysis showed that the cross-sectional images retained structural information up to a medium resolution.

Amino Acid Sequence↗