Biomedical subjects

K Goto

Publications and source records attributed to K Goto.

At least 289 records · Page 16Linked to original sources

PubMed1997

Adenovirus-mediated gene transfer of basic fibroblast growth factor induces in vitro angiogenesis.

To investigate the possibility of adenovirus-mediated gene transfer in the treatment of vascular occlusive diseases, we constructed a replication-deficient recombinant adenovirus vector coding for human basic fibroblast growth factor (bFGF) and examined its effect on the proliferation and differentiation of vascular endothelial cells in vitro. Human umbilical vein endothelial cells (HUVECs) were successfully infected with high efficiency and expressed 18 kD protein which is immunoreactive to anti-bFGF monoclonal antibody. This protein was accumulated mainly in the nuclei of the cells, but was also detected in the culture medium although the complimentary DNA (cDNA) did not contain the classical secreting signal sequence. The proliferation assay of HUVECs infected with bFGF-expressing adenovirus revealed a significant increase in cell number over control. Infection with this virus also enhanced tubular formation of HUVECs on reconstituted basement membrane. Neovascularization and the formation of collateral vessels play important roles in minimizing tissue damage in ischemic disorders. These results imply that the use of bFGF-expressing recombinant adenovirus may be a suitable in vivo gene therapy for ischemic diseases.

Adenoviridae↗

PubMed1997

Nucleotide sequence analysis of the HLA class I region spanning the 237-kb segment around the HLA-B and -C genes.

To elucidate the detailed gene organization of the human leukocyte antigen (HLA) class I region on chromosome 6, seven contiguous cosmid genomic clones covering the 237-kb segment around the HLA-B and -C loci were subjected to DNA sequencing by the shotgun strategy to give a single contig of 236,822 bp from the MICA gene (58.2 kb centromeric of HLA-B) to 90.8 kb telomeric of HLA-C. This region was confirmed to contain four known genes, MICA, HLA-17, HLA-B, and HLA-C, from centromere to telomere. Further, a new member of the P5 multicopy genes was found to be about 1.3 kb upstream of the HLA-17 gene and designated P5.8. Five novel genes designated NOB1-5 were identified by RT-PCR and Northern blot hybridization. In addition, two pseudogenes, dihydrofolate reductase pseudogene (DHFRP) and ribosomal protein L3 homologous gene (RPL3-Hom), were also found in the vicinity of the HLA-B and -C genes, respectively. The two segments (about 40 kb) downstream of the HLA-B and HLA-C genes showed high sequence homology to each other, suggesting that segmental genome duplication including the major histocompatibility complex (MHC) class I gene must have occurred during the evolution of the MHC.

Blotting, Northern↗

PubMed1997

Neurotoxic effects of papaverine, tetrahydropapaverine and dimethoxyphenylethylamine on dopaminergic neurons in ventral mesencephalic-striatal co-culture.

We report neurotoxic effects of papaverine, tetrahydropapaverine, dimethoxyphenylethylamine (DMPEA), and 1-methyl-4-phenylpyridinium ion (MPP+) on dopaminergic neurons in ventral mesencephalic-striatal co-culture. These compounds have been reported as mitochondrial toxins which may be implicated in the etiology and pathogenesis of Parkinson's disease. Tyrosine hydroxylase (TH)-positive neurons were decreased in dose-dependent manner by these compounds. Papaverine and MPP+ were most toxic to TH-positive neurons among the compounds tested. The order of the toxicity on TH-positive neurons was papaverine, MPP+, tetrahydropapaverine and then DMPEA. This order of toxicity was approximately the same as that reported on the inhibitory effect of these compounds on NADH-linked mitochondrial respiration and complex I activity. These findings indicate that the presence of dimethoxy residues in the catechol ring augments toxicity to dopaminergic neurons in culture.

1-Methyl-4-phenylpyridinium↗

PubMed1997

Cloning of a novel human diacylglycerol kinase (DGKtheta) containing three cysteine-rich domains, a proline-rich region, and a pleckstrin homology domain with an overlapping Ras-associating domain.

Diacylglycerol kinase (DGK) attenuates levels of second messenger diacylglycerol in cells and produces another (putative) messenger, phosphatidic acid. We have previously purified a 110-kDa DGK from rat brain (Kato, M., and Takenawa, T. (1990) J. Biol. Chem. 265, 794-800). Here we report the cDNA cloning from human brain and retina cDNA libraries. The cDNA encodes a novel DGK isotype, termed DGKtheta, of 941 amino acids with an apparent molecular mass of 110 kDa. DGKtheta contains a C-terminal putative catalytic domain, which is present in all eukaryotic DGKs. In contrast to other DGK isotypes, DGKtheta contains three cysteine-rich domains instead of two. The third cysteine-rich domain is most homologous to the second one in other DGK isotypes. This particular sequence homology extends C-terminally beyond the typical cysteine/histidine core structure and is DGK-specific. DGKtheta furthermore contains various domains for protein-protein interaction, such as a proline- and glycine-rich domain with a putative SH3 domain-binding site and a pleckstrin homology domain with an overlapping Ras-associating domain. DGKtheta is expressed in the brain and, to a lesser extent, in the small intestine, duodenum, and liver. In situ hybridization of DGKtheta mRNA in adult rat brain reveals high expression in the cerebellar cortex and hippocampus. DGKtheta activity in COS cell lysates is optimal toward diacylglycerols containing an unsaturated fatty acid at the sn-2 position.

Amino Acid Sequence↗

PubMed1997

Gene cloning and characterization of CDP-diacylglycerol synthase from rat brain.

A cDNA encoded a 462-amino acid protein, which showed CDP-diacylglycerol synthase (CDS) activity was cloned for the first time as the vertebrate enzyme molecule from rat brain cDNA library. The deduced molecular mass of this rat CDS was 53 kDa, and putative primary structure included several possible membrane- spanning regions. At the amino acid sequence level, rat CDS shared 55.5%, 31. 7%, and 20.9% identity with already known Drosophila, Saccharomyces cerevisiae, and Escherichia coli CDS, respectively. This rat CDS preferred 1-stearoyl-2-arachidonoyl phosphatidic acid as a substrate, and its activity was strongly inhibited by phosphatidylglycerol 4, 5-bisphosphate. By immunoblotting analysis of COS cells overexpressed with the epitope-tagged for rat CDS, a 60-kDa band was detected. By epitope-tag immunocytochemistry, the CDS protein was mainly localized in close association with the membrane of the endoplasmic reticulum of the transfected cells. The intense mRNA expression of CDS was localized in the cerebellar Purkinje cells, the pineal body, and the inner segment of photoreceptor cells. Additionally, very intense expression was detected in postmitotic spermatocytes and spermatids.

Amino Acid Sequence↗

PubMed1997

Role of endothelin-1 in astrocyte responses after acute brain damage.

We examined the possibility of the involvement of endothelin (ET)-1, a potent vasoactive peptide, in the process of astrocyte proliferation after brain injury. Acute brain damage in rats was induced by cold-injury. Astrocytes changed from a differentiated state to an immature, RC-1-positive state immediately after the injury. In the injured site, the level of ET-1-like immunoreactivity in the tissue was significantly increased on the first postoperative day and was sustained at a high level for 5 days. ET(B) receptor mRNA was markedly but transiently down-regulated only on the first day after the injury. Brain extracts (BE) were prepared from the injured tissues, and their effects on the proliferative characteristics of astrocytes were examined in primary culture of astrocytes. The flat morphology, which was observed in association with cell proliferation, and DNA synthesis of astrocytes were enhanced by treatment with each of the BE from 1 (D1-BE), 3 and 5 days after the injury. A monoclonal antibody that recognizes the C-terminus of rat ET-1 and ET-3 inhibited the DNA synthesis of astrocytes induced by D1-BE. These results provide experimental evidence that ET-1 may participate in the initiation of gliosis in the acute phase of brain damage.

Acute Disease↗

PubMed1997

Noradrenergic activity and spontaneous recurrence of methamphetamine psychosis.

The process that triggers flashbacks due to previous methamphetamine (MAP) psychosis was studied in 28 flashbackers, along with 84 non-flashbackers with a history of MAP psychosis. We measured plasma monoamine metabolite levels in 12 of the flashbackers and eight of the non-flashbackers, along with 28 normal controls. Most flashbackers had undergone frightening experiences during previous MAP use. The dominant triggering factor was a mild fear of other people. Plasma norepinephrine (NE) levels in the 12 flashbackers were increased during flashbacks. Thus, MAP use associated with threatening experiences may have increased sensitivity to stressors, leading to the occurrence of flashbacks, including exaggerated noradrenergic activity.

Adult↗

PubMed1997

Novel regulation of delta-aminolevulinate synthase in the rat harderian gland.

The mode of expression of delta-aminolevulinate synthase (ALAS), as well as that of mRNAs for other heme pathway enzymes, was examined in the rat Harderian gland. Northern blot and in situ hybridization analyses demonstrated that the non-specific ALAS (ALAS-N) mRNA is highly expressed in this tissue, whereas the erythroid-specific ALAS (ALAS-E) mRNA is not. Immunoblot analysis of ALAS also confirmed this finding at the protein level. ALAS-N mRNA was maximally induced in the Harderian gland and was not increased further by treatment of animals with 2-allyl-2-isopropylacetamide (AIA). The levels of mRNAs for other heme pathway enzymes, i.e., delta-aminolevulinate dehydratase, porphobilinogen deaminase, uroporphyrinogen decarboxylase, and coproporphyrinogen oxidase, also were increased markedly in the Harderian gland and not influenced by AIA treatment. The level of ferrochelatase (FeC) mRNA in the gland was, however, lower than that in the liver. The gland contained an extremely high level of protoporphyrin, while heme was undetectable. Microsomal heme oxygenase-1 (HO-1) mRNA levels were significantly higher in the Harderian gland than in the liver. When isolated glands were incubated with hemin in vitro in organ cultures, the level of HO-1 mRNA was increased, whereas the ALAS-N mRNA level was not. These findings indicate that markedly elevated levels of protoporphyrin and extremely low levels of heme in the Harderian gland are the results of both decreased expression of FeC and markedly increased expression of ALAS-N and HO-1. The constitutive expression of the ALAS-N gene in the Harderian gland suggests a novel transcriptional control mechanism of this gene.

5-Aminolevulinate Synthetase↗

PubMed1997

Studies on endothelium-dependent vasorelaxation by hydralazine in porcine coronary artery.

Hydralazine relaxed porcine coronary artery strips in a concentration-dependent manner by distinct endothelium-dependent and endothelium-independent actions. With lower doses (< or = 10(-6) M), the hydralazine-induced relaxation appears to be completely endothelium-dependent and we designed the present study to elucidate the mechanisms of this endothelium-dependent relaxation. Hydralazine (10(-6) M)-induced endothelium-dependent relaxation was not affected by the presence of 10(-5) M indomethacin, 10(-3) M L-NG-nitro-arginine (L-NOARG) or 10(-5) M haemoglobin, and was accompanied by accumulation of cGMP but not of cAMP in artery strips. There was a close time-dependent parallel relationship between endothelium-dependent relaxation and accumulation of cGMP induced by hydralazine (10(-6) M). The endothelium-dependent relaxation and accumulation of cGMP induced by hydralazine showed much slower kinetics than those induced by ionomycin (10(-7) M). Pretreatment of the strips with actinomycin D (10 micrograms/ml) significantly inhibited not the endothelium-dependent relaxation and accumulation of cGMP induced by ionomycin (10(-7) M) but those induced by hydralazine (10(-6) M). These results suggest that hydralazine induces endothelium-dependent vasorelaxation via the slow accumulation of cGMP in the strips. This does not occur through the release of nitric oxide or prostaglandin I2 but through immediate transcription and probably expression of a molecule in the endothelium.

Animals↗

PubMed1997

Triplet repeat polymorphism in the transmembrane region of the MICA gene: a strong association of six GCT repetitions with Behçet disease.

A member of a novel family of the human major histocompatibility complex (MHC) class I genes termed MIC (MHC class I chain-related genes), MICA, has been recently identified near the HLA-B gene on the short arm of human chromosome 6. The predicted amino acid sequence of the MICA chain suggests that it folds similarly to typical class I chains and may have the capacity to bind peptides or other short ligands. Therefore, MICA is predicted to have a specialized function in antigen presentation or T cell recognition. During nucleotide sequence analyses of the MICA genomic clone, we found a triplet repeat microsatellite polymorphism of (GCT/AGC)n in the transmembrane (TM) region of the MICA gene. In 68 HLA homozygous B cell lines, 5 distinct alleles of this microsatellite sequence were detected. One of them contained an additional one base insertion that created a frameshift mutation resulting in a premature termination codon in the TM region. This particular allele may encode a soluble, secreted form of the MICA molecule. In addition, we have investigated this microsatellite polymorphism in 77 Japanese patients with Behcet disease, which is known to be associated with HLA-B51. The microsatellite allele consisting of 6 repetitions of GCT/AGC was present at significantly higher frequency in the patient group (Pc = 0.00055) than in a control population. Furthermore, the (GCT/AGC)6 allele was present in all B51 positive patients and in an additional 13 B51 negative patients. These results suggest the possibility of a primary association of Behcet disease with MICA rather than HLA-B.

Asian People↗

PubMed1997

Nitric oxide-mediated vasorelaxation induced by sodium polyoxyethylene laurylether sulfate.

Ingestion of surfactants is known to cause hemodynamic changes with decreased total vascular resistance. Motivated by this clinical observation, we investigated the direct effects of a common anionic surfactant, sodium polyoxyethylene laurylether sulfate (LES), on isolated ring segments of rat thoracic aorta. LES did not produce any vasocontractile responses, but relaxed ring segments precontracted with 10(-6) M phenylephrine in a concentration-dependent manner. This LES-induced vasorelaxation was significantly reduced by the removal of endothelium or pretreatment with N(G)-nitro-L-arginine methylester hydrochloride, methylene blue, or oxyhemoglobin to the same degree, but was not affected by pretreatment with indomethacin. A further study measuring NO2- plus NO3- (NO(x), total metabolites of NO) in the medium of calf pulmonary artery endothelial (CPAE) cells, a cultured cell line, revealed that LES caused a significant increase in NO(x) production. On the other hand, in a study measuring intracellular Ca2+ in fura-2-loaded CPAE cells, LES caused a significant increase in intracellular Ca2+. These results suggest that LES causes endothelium-dependent vasorelaxation via a NO-mediated signaling pathway, which might be due to Ca2+ mobilization.

Animals↗

PubMed1997

Cardiovascular effects of a herbicide containing glufosinate and a surfactant: in vitro and in vivo analyses in rats.

A herbicide, Basta (BASTA), containing glufosinate ammonium (GLA) as the main component and an anionic surfactant, sodium polyoxyethylene alkylether sulfate (AES), causes hemodynamic changes characterized by a decrease in total vascular resistance with an increase or a decrease in cardiac output in human acute oral poisoning. With a motivation based on these clinical observations, we tried to elucidate the exact component and its mode of action that is mostly responsible for the direct cardiovascular effects of this herbicide formulation, investigating the effects of BASTA, GLA, and AES independently on the cardiovascular system in rats in vitro and in vivo. In isolated right atria beating spontaneously in Krebs-Ringer's solution, BASTA and AES produced negative chronotropic responses in a concentration-dependent manner. In electrically driven isolated left atria, BASTA and AES produced positive inotropic responses concentration dependently but negative inotropic responses at extremely high concentrations. In aortic ring segments, BASTA and AES produced no vasoconstrictive effects but exerted significant vasodilative effects when the aortic ring was precontracted with phenylephrine. These in vitro responses caused by BASTA and AES occurred to a similar degree. On the other hand, the main component, GLA, produced no effects in isolated atria and aortas. In anesthetized rats, relatively low doses of BASTA and AES produced a decrease in blood pressure followed by a slight increase in heart rate, which was presumably due to baroreflex caused by the decrease in blood pressure. At an extremely high dose, BASTA and AES produced a decrease in blood pressure with a marked decrease in heart rate. These in vivo responses to BASTA and AES also occurred to a similar degree. In contrast, the main component, GLA, did not produce any effects on heart rate and blood pressure in anesthetized rats. From these results, we concluded that the effects of BASTA in our in vivo experiments were not caused by the main component, GLA, but was mostly caused by AES through its vasodilative effects plus cardiostimulatory effects at low doses and cardiosuppressive effects at high doses.

Aminobutyrates↗

PubMed1997

Primary osteosarcoma of the urinary bladder.

Primary osteosarcoma of the bladder, together with transitional cell carcinoma, occurred in a 74-year-old female presenting with haematuria and lumbago. She was treated with chemotherapy and radical cystectomy. Though it was conceived to be curative, she died of a recurrence 5 months after the operation. Primary osteosarcoma of the bladder is an unusual and highly malignant disease. In spite of radical therapy, the outcome has been dismal with some exceptions.

Aged↗

PubMed1997

Zinc depletion suppresses tumor growth in mice.

The hypothesis that in tumor-bearing animals an increase of host hepatic zinc metallothionein (Zn-MT) causes a restriction of zinc in the tumor tissue was studied. Three types of tumors were induced in laboratory mice by cell transplant. Tumor growth appears to be inhibited under zinc-deficient conditions, even in cases where zinc deficiency was started after tumor cell transplant. The survival times of tumor-bearing mice were prolonged by administration of cadmium chloride, which induces the synthesis of a combined zinc-cadmium metallothionein derivative in the host liver, but not in the tumor tissue, leading to an increase of hepatic zinc in the treated animals. The uptake of 65Zn by the liver of Cd-treated, tumor bearing mice was significantly higher than that of controls whereas uptake of 65Zn by tumor cells was significantly higher in controls than in the treated animals. These results suggest that restriction of zinc intake suppresses tumor growth.

Animals↗

PubMed1997

Usefulness of novel imaging modalities in diagnosis of focal nodular hyperplasia of the liver.

A 17-year-old woman was admitted because of a liver tumor found incidentally by ultrasonography. Liver function was normal and there were no markers of hepatitis viruses or malignancy. Abdominal ultrasonography, computed tomography (CT), and magnetic resonance imaging revealed a mass (2 cm in diameter) in the lateral segment of the left lobe of the liver. The lesion was not detected by hepatic arteriography. However, dynamic CT with fast scanning and dynamic CO2-enhanced ultrasonography demonstrated initial central enhancement of the mass followed by centrifugal spread of enhancement to the periphery. Color Doppler flow imaging detected a central color spot, shown to be an artery by a pulsed Doppler spectrum analysis. Fine-needle biopsy confirmed a diagnosis of focal nodular hyperplasia. Dynamic CT with fast scanning, dynamic CO2-enhanced ultrasonography, and color Doppler flow imaging were useful in detecting the vascular pattern specific to focal nodular hyperplasia. Investigation of further cases with these novel imaging modalities should help to establish a comprehensive diagnostic procedure and thus avoid unnecessary surgery for focal nodular hyperplasia, which is a completely benign lesion.

Adolescent↗

PubMed1997

Bosentan, a novel synthetic mixed-type endothelin receptor antagonist, attenuates acute gastric mucosal lesions induced by indomethacin and HCl in the rat: role of endogenous endothelin-1.

Endothelin-1 has been reported to be responsible for gastric mucosal damage in various experimental models. We evaluated the role of endogenous endothelin-1 in the pathogenesis of gastric mucosal damage induced by indomethacin and HCl in the rat. Rats were given indomethacin (25 mg/kg) subcutaneously, and 15 min later, 0.2N HCl intragastrically. Gastric mucosal damage, gastric endogenous endothelin-1, and gastric mucosal hemodynamics were measured. The effects of bosentan, a mixed endothelin receptor antagonist, on gastric mucosal integrity and hemodynamics were assessed. Gastric endogenous endothelin-1 was significantly elevated at 20 min, gastric mucosal blood flow began to decrease significantly at 25 min, and gastric damage occupied 52.2% of the total glandular mucosa at 135 min after injection of indomethacin. Intragastric pretreatment with bosentan (5, 10, 30, and 60 mg/kg) significantly attenuated gastric damage, to 26.1%, 7.7%, 3.6%, and 1.6%, respectively, of the total glandular mucosa. Bosentan (60 mg/kg) prevented the initial decrease of blood flow and, even at 135 min, improved blood flow and hemoglobin oxygen saturation significantly. We suggest that indomethacin-induced endogenous endothelin-1 diminishes gastric mucosal blood flow and tissue oxygenation and ultimately causes gastric damage. Endogenous endothelin-1 may play an important role in the pathogenesis of the acute gastric mucosal lesions induced by indomethacin and HCl.

Animals↗

PubMed1997

Precipitating factors in spontaneous recurrence of methamphetamine psychosis.

This paper examines noradrenergic hyperactivity in response to stress in the development of spontaneous recurrences of methamphetamine (MAP) psychosis, a phenomenon known as flashbacks, in studies of psychedelic drug use. We studied predictors of flashbacks in 36 subjects with flashbacks, along with 80 subjects with a history of MAP psychosis who did not experience flashbacks. Plasma monoamine metabolite levels were assayed in 26 of the 36 subjects with flashbacks, 16 of the 80 subjects without flashbacks, nine subjects with persistent MAP psychosis, and 28 normal controls. None of the 28 controls became psychotic. A square root transformation was applied to all monoaminergic values, resulting in data nearly normally distributed. The subjects with flashbacks had been exposed to stressful events or threatening paranoid-hallucinatory states or both during previous MAP use. Most flashbacks occurred under conditions that provoked a mild fear of other people. Plasma norepinephrine levels were markedly increased during flashbacks. Thus, stressful experiences together with MAP use may have induced noradrenergic hyperreactivity to a mild stress, which in turn may elicit memories of MAP psychosis associated with stressful experiences. A mild fear of other people precipitated the flashbacks, including markedly increased noradrenergic activity. The results of this study suggest that noradrenergic hyperreactivity to a mild stress is a precipitating factor in spontaneous recurrences of MAP psychosis.

Adult↗

PubMed1997

Allelic variants of the human MHC class I chain-related B gene (MICB).

The human major histocompatibility complex (MHC) is located within a 4 megabase segment on chromosome 6p21.3. Recently, a highly divergent MHC class I chain-related gene family, MIC was identified within the class I region. The MICA and MICB genes in this family have unique patterns of tissue expression. The MICA gene is highly polymorphic, with more than 20 alleles identified to date. To elucidate the extent of MICB allelic variations, we sequenced exons 2 (alpha 1), 3 (alpha 2), 4 (alpha 3), and 5 (transmembrane) as well as introns 2 and 4 of this gene in 46 HLA homozygous B-cell lines. We report the identification of eleven alleles based on seven non-synonymous, two synonymous, and four intronic nucleotide variations. Interestingly, one allele has a nonsense mutation resulting in a premature termination codon in the alpha 2 domain. Thus, MICB appears to have fewer alleles than MICA, not unlike the allelic ratio between the HLA-C and -B loci. A preliminary linkage analysis of the MICB alleles with those of the closely located MICA and HLA-B genes revealed no conspicuous linkage disequilibrium between them, implying the presence of a potential recombination hotspot between the MICB and MICA genes.

Alleles↗