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Biomedical subjects

H Kondo

Publications and source records attributed to H Kondo.

At least 127 records · Page 7Linked to original sources
PubMed2000

Attenuation of expression of gamma-glutamylcysteine synthetase by ribozyme transfection enhance insulin secretion by pancreatic beta cell line, MIN6.

Low levels of intracellular antioxidant enzyme activities as well as glutathione (GSH) concentrations have been described in pancreatic beta cells. We examined the effects of intracellular GSH depletion on insulin secretion and the role of intracellular GSH in signal transduction in beta cell line, MIN6 cells. Anti-gamma-glutamylcysteine synthetase (gamma-GCS) heavy subunit ribozyme was stably transfected to MIN6 cells to reduce intracellular GSH concentration. In the presence of 10 mM glucose, ribozyme-transfected cells (RTC) increased insulin secretion from 0.58 microg/10(6) cells/h in control cells (CC) to 1.48 microg/10(6) cells/h. This was associated with increased intracellular Ca(2+) concentration in RTC, detected by fluo-3 staining. Our results demonstrated that intracellular GSH concentration might influence insulin secretion by MIN6 cells, and suggest that enhanced insulin secretion by beta cells conditioned by chronic depletion of GSH is mediated by increased intracellular Ca(2+) concentration.

Adenosine Triphosphate↗
PubMed2000

Immunohistochemical study of Pneumocystis carinii infection in pigs: evaluation of Pneumocystis pneumonia and a retrospective investigation.

Infection with Pneumocystis carinii was demonstrated immunohistochemically in the lungs of pigs 15 to 75 days of age from a herd with epidemic pneumonia due to the organism. The distribution of the organism was centered on the airways, and extended progressively with age from the alveolar ducts to the alveoli. In a retrospective immunohistochemical study of 245 newborn to adult pigs which were necropsied between 1988 and 1995, P carinii infection was found in 87 pigs (35.5 per cent) aged between 17 days to seven months. In the pigs aged between one and three months the infection rate was 63.1 per cent. Pigs from herds in which suckler and weaner pigs shared the same air space were more heavily infected than those from the herds in which they were reared separately. There were no regional or seasonal variations in the level of infection, and the infection was not associated with any single disease.

Animals↗
PubMed2000

Calcineurin inhibitor attenuates left ventricular hypertrophy, leading to prevention of heart failure in hypertensive rats.

BACKGROUND: There is controversy regarding the contribution of calcineurin activation to the development of pressure-overload left ventricular (LV) hypertrophy and heart failure. The aim of this study was to explore whether the inhibition of calcineurin may prevent the transition to heart failure in hypertensive rats and, if so, to clarify in which developmental stage of LV hypertrophy calcineurin plays a key role. METHODS AND RESULTS: Dahl salt-sensitive rats placed on an 8% NaCl diet from the age of 7 weeks (hypertensive rats) were randomized to no treatment (n=6) or treatment with the calcineurin inhibitor FK506 (1 mg x kg(-1) x d(-1)) from 8 weeks (FKE, n=7) or from 17 weeks (FKL, n=7). Rats placed on a 0.3% NaCl diet were defined as control rats (n=6). The administration of FK506 from 8 weeks attenuated, although it did not block, LV hypertrophy observed in the untreated rats and prevented the transition to heart failure. The development of LV fibrosis, however, was not attenuated by the administration of FK506 from 8 weeks. The administration of FK506 from 17 weeks brought no benefit for cardiac remodeling or LV function and failed to prevent heart failure. CONCLUSIONS: Calcineurin inhibition, if started from the initial stage of pressure overload, attenuated the development of LV hypertrophy without any effect on LV fibrosis and prevented the transition to heart failure. The activation of calcineurin is involved in the development of LV hypertrophy but not of LV fibrosis, and this involvement may be crucial at the initial stage.

Animals↗
PubMed2000

A solid-phase synthesis for beta-turn mimetics of sialyl Lewis X.

A solid-phase synthesis of heterocyclic beta-turn mimetics of sialyl Lewis X, which is a natural carbohydrate ligand of selectins, was established. This synthetic method could be very useful for drug discovery of selectin antagonists using combinatorial chemistry techniques.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

Impact of Helicobacter pylori infection on gastric cancer incidence in a general Japanese population: the Hisayama study.

BACKGROUND: Several nested case-control studies have reported the potentially causal relationship between Helicobacter pylori infection and the development of gastric cancer. However, there has been no prospective study evaluating this issue. The purpose of this study is to examine the impact of H pylori infection on gastric cancer occurrence in a general Japanese population (Hisayama, Japan) stratified according to sex, using a prospective study design. METHODS: A total of 2602 subjects aged 40 years or older (1070 men; mean age, 57 years; 1532 women; mean age, 59 years) without a history of gastrectomy or gastric cancer were classified according to the status of the serum IgG antibodies to H pylori and observed prospectively for 9 years from 1988. RESULTS: Infection of H pylori was more common in men (71.5%) than in women (62.5%; P<.001). The age-adjusted incidence of gastric cancer for men (5.3 per 1000 person-years) was 4-fold higher than that for women (1.3; P<.001). In men, the age-adjusted incidence of gastric cancer was significantly higher in the subjects with H pylori infection than in those without it (6.2 vs 2.5; relative risk, 2.59 [95% confidence interval, 1.03-6.50]), whereas no significant difference was observed in women (1.2 vs 1.1; relative risk, 0.99 [95% confidence interval, 0.36-2.68]). These results were similar even after controlling for other risk factors in multivariate analysis. It was estimated that 40.1% of gastric cancers for men in this cohort were attributable to H pylori infection. CONCLUSION: A significant relationship exists between infection with H pylori and subsequent occurrence of gastric cancer for men but not for women in this Japanese population.

Adult↗
PubMed2000

Isolation of Neospora caninum from the brain of a naturally infected adult dairy cow.

Neospora caninum was isolated from the brain of a 2-year-old dairy cow that had aborted confirmed N. caninum-infected fetuses on two occasions. The cow had an indirect fluorescent antibody titer of 1:1600 to N. caninum. The cow was killed 24 days after its second abortion and the brain was bioassayed for N. caninum in nude mice. Multifocal areas of perivascular cuffing and glial nodules were observed in the cerebrum and mesencephalon of the cow, but N. caninum was not identified in histological sections of the brain. All three nude mice inoculated with brain homogenate of the cow, developed emaciation and paralysis. Microscopical examination of the nude mice revealed systemic N. caninum infection with demonstrable tachyzoites in various organs. The parasites isolated from fresh mouse brain were transferred successfully into Vero cell cultures. PCR procedure on the purified tachyzoites obtained from the Vero cell cultures amplified the specific DNA sequence for N. caninum.

Animals↗
PubMed2000

Human fetal skin fibroblast migration stimulated by the autocrine growth factor bFGF is mediated by phospholipase A(2) via arachidonic acid without the involvement of pertussis toxin-sensitive G-protein.

We reported previously that human fetal skin fibroblast migration into a denuded area was stimulated by an autocrine factor, basic fibroblast growth factor (bFGF). Since the signal transduction pathway of this migration is unknown, we attempted to clarify it by comparing this fibroblast migration with a previously reported bovine endothelial cell migration into a wounded area stimulated by an addition of bFGF, in which the bFGF signal was mediated by phospholipase A(2)-coupled G-protein and phospholipase A(2) (PLA(2)) via arachidonic acid. Our study demonstrated that pertussis toxin, a specific inhibitor of PLA(2)-coupled G-protein, did not suppress human fetal skin fibroblast migration, but 2-(p-amylcinnamyl)amino-4-chlorobensoic acid (ONO-RS-082), a PLA(2) inhibitor, did. Since ONO-RS-082 is a non-specific PLA(2) inhibitor, a cytoplasmic, Ca-dependent PLA(2) (cPLA(2)) inhibitor, AACOCF3, was examined. AACOCF3 suppressed cell migration in certain concentrations. The PLA(2) inhibitor-suppressed cell migration was restored by adding arachidonic acid, and cell migration suppressed by anti-bFGF antibodies was restored by adding arachidonic acid. In addition, pertussis toxin did not suppress arachidonic acid release, which shows an action of PLA(2), but AACOCF3 did. These results indicate that human fetal skin fibroblast migration stimulated by an autocrine factor, bFGF, was mediated by PLA(2) via arachidonic acid without the involvement of PLA(2)-coupled G-protein.

Aminobenzoates↗
PubMed2000

Type I phosphatidylinositol 4-phosphate 5-kinase directly interacts with ADP-ribosylation factor 1 and is responsible for phosphatidylinositol 4,5-bisphosphate synthesis in the golgi compartment.

Phosphatidylinositol (PtdIns) 4,5-bisphosphate is involved in many aspects of membrane traffic, but the regulation of its synthesis is only partially understood. Golgi membranes contain PI 4-kinase activity and a pool of phosphatidylinositol phosphate (PIP), which is further increased by ADP-ribosylation factor 1 (ARF1). COS7 cells were transfected with alpha and beta forms of PI 4-kinase, and only membranes from COS7 cells transfected with PI 4-kinase beta increased their content of PIP when incubated with ARF1. PtdIns(4, 5)P(2) content in Golgi membranes was nonexistent but could be increased to a small extent upon adding either cytosol or Type I or Type II PIP kinases. However, when ARF1 was present, PtdIns(4,5)P(2) levels increased dramatically when membranes were incubated in the presence of cytosol or Type I, but not Type II, PIP kinase. To examine whether ARF1 could directly activate Type I PIP 5-kinase, we used an in vitro assay consisting of phosphatidycholine-containing liposomes, ARF1, and PIP 5-kinase. ARF1 increased Type I PIP 5-kinase activity in a guanine nucleotide-dependent manner, identifying this enzyme as a direct effector for ARF1.

ADP-Ribosylation Factor 1↗
PubMed2000

Neurons containing Alz-50-immunoreactive granules around the cerebral infarction: evidence for the lysosomal degradation of altered tau in human brain?

Little is known about the metabolic process of tau and tau-derived substances. Alz-50- and tau 2-immunoreactivities in intracellular granules of neurons were observed in regions surrounding infarcted foci in the human cerebral cortex. Ultrastructurally, these granules in the fresh infarcted region exhibited primary lysosome-like structures, while those in old infarctions were lipofuscin. These findings indicate that tau is metabolized within lysosomes in neurons damaged by ischemic injury in human cortical penumbra. Alz-50-positive granules were more prominent in fresh infarction than in old infarction. After undergoing degradation and modification, altered tau might remain, at least partially, in secondary lysosomes.

Aged↗
PubMed2000

Study on selectin blocker. 8. Lead discovery of a non-sugar antagonist using a 3D-pharmacophore model.

We have developed a pharmacophore model of a ligand/E-selectin complex to screen drug candidates for selectin blockers. In a series of sugar mimetic studies of the E-selectin ligand, sialyl Lewis X (sLe(x)), we have already found a potent compound, a sulfated Le(x) analogue (1), and also have proposed how compound 1 binds to E-selectin (Tsujishita, H.; Hiramatsu, Y.; Kondo, N.; Ohmoto, H.; Kondo, H.; Kiso, M.; Hasegawa, A. J. Med. Chem. 1997, 40, 362-369). To find drug candidates that fit into the binding pocket of E-selectin, we constructed an original 3D-pharmacophore model from structural information of a compound 1/E-selectin complex model and screened lead compounds for selectin blockers using a commercially available database ACD-3D. As a result, we discovered a lead compound (2) containing good selectin inhibitory activity, and in addition, we succeeded to preliminarily optimize it to a more active lead compound (3) with micromolar IC(50) values, based on the 3D-pharmacophore model investigation. This methodology using the 3D-pharmacophore model could be applicable as a pre-screen system for selectin blockers.

Benzamides↗
PubMed2000

Regulation of long-term potentiation by H-Ras through NMDA receptor phosphorylation.

The proto-oncogene ras plays a critical role in cell proliferation and differentiation. However, ras genes are abundantly expressed in the adult CNS, although neuronal cells normally do not proliferate. Recently, several lines of evidence implicated the involvement of Ras signaling pathway in synaptic plasticity. To explore the role of the Ras proteins in the CNS, we generated knock-out mice lacking the H-ras gene and then used them to study the roles of Ras in synaptic transmission and plasticity. An investigation of protein phosphorylation and synaptic transmission in H-ras null mutant mice has shown that the NMDA receptor is a final target molecule of the Ras protein pathway in the CNS. In the H-ras null mutant hippocampus, the tyrosine phosphorylation of NR2A (epsilon1) and NR2B (epsilon2) subunits of NMDA receptors is increased, and, correspondingly, NMDA synaptic responses are selectively enhanced. In addition, long-term potentiation is markedly enhanced in mutant mice, most likely because of a selective enhancement of NMDA synaptic responses. Therefore, although Ras proteins have been implicated in cell proliferation and differentiation, the regulation of activity-dependent synaptic plasticity in the adult animals by downregulation of the phosphorylation of the NMDA receptor may be another major and pivotal role for H-Ras protein.

Animals↗
PubMed2000

Localization of mRNAs for phospholipase D (PLD) type 1 and 2 in the brain of developing and mature rat.

Phospholipase D (PLD) is known as one of the key enzymes in the lipid metabolism which produces several second messengers. We demonstrated the localization of the gene expression for PLD1 and PLD2 using in situ hybridization histochemistry in the brain of developing and mature rats. Whereas PLD1 mRNA expression was detected mainly in presumptive oligodendrocytes, PLD2 mRNA expression was detected mainly in presumptive astrocytes. In addition, the gene expression for PLDs were expressed in neuroepithelial cells of the ventricular/ependymal zones and the gene for PLD2 was expressed transiently in early postnatal gray matters, presumptive neurons.

Age Factors↗
PubMed2000

DNA sensing on a DNA probe-modified electrode using ferrocenylnaphthalene diimide as the electrochemically active ligand.

Naphthalene diimide derivative 1 carrying ferrocenyl moieties at the termini of imide substituents binds intact calf thymus DNA 4 times more strongly than the denatured DNA, and its complex with the intact DNA dissociates 80 times more slowly than that with the denatured DNA. On the basis of these observations, ligand 1 was applied to a probe of electrochemical DNA sensing. A thiol-linked single-stranded DNA probe was immobilized through the S-Au bonding to 20-30 pmol/mm2 on a gold electrode. Following hybridization with the complementary DNA, the electrode was soaked in a solution containing 1 (intercalation step) and then washed with buffer for 5 s. The cyclic voltammogram and differential pulse voltammogram for this electrode gave an electrochemical signal due to the redox reaction of 1 that was bound to the double-stranded DNA on the electrode. Thus, dA20 and the yeast choline transport gene were quantitated at the subpicomole level. The sensitivity of DNA detection was improved to 10 zmol by reducing the amount of immobilized DNA probe and protecting the uncovered surface of the electrode with 2-mercaptoethanol.

Base Sequence↗
PubMed2000

Amino acids and peptides. LVII. Synthetic peptide with a sequence of ribonuclease from Sulfolobus solfataricus, SSR(1-62), does not function as an RNase.

The 62 residue peptide, SSR(1-62), whose sequence corresponds to that of ribonuclease (RNase) from Sulfolobus solfataricus, and its related peptides, SSR(1-22) and SSR(10-62), were chemically synthesized and their RNase activity and DNA-binding activity were examined. The RNase activity assay using yeast RNA or tRNA(fMet) as substrate showed that the synthetic peptide SSR(1-62) did not hydrolyze yeast RNA or tRNA(fMet). These data were not consistent with previous reports that both the native peptide isolated from S. solfataricus [Fusi et al. (1993) Eur. J. Biochem. 211, 305-311] and the recombinant peptide expressed in Escherichia coli [Fusi et al. (1995) Gene 154, 99-103] were able to hydrolyze tRNA(fMet). However, the synthetic SSR(1-62) exhibited DNA-binding activity. In the presence of synthetic SSR(1-62), the cleavage of DNA (plasmid pUCRh2-4) by restriction endonuclease (EcoRI) was not observed, suggesting that synthetic SSR(1-62) bound to DNA protected DNA from its enzymatic digestion. Neither SSR(1-22) nor SSR(10-62) prevented DNA from being cleaved by a restriction enzyme. These findings strongly suggest the importance of not only the N-terminal region of SSR(1-62) but also the C-terminal region for DNA-binding. Circular dichroism spectroscopy of synthetic SSR(1-62) indicated a beta-sheet conformation, in contrast with synthetic SSR(1-22), which exhibited an unordered conformation.

Amino Acid Sequence↗
PubMed2000

Localization of mRNA for SHIP2, SH2 domain-containing inositol polyphosphate 5-phosphatase, in the brain of developing and mature rats.

The localization of mRNA for SHIP2, SH2 domain containing inositol 5-phosphatase SHIP isozyme, was examined by in situ hybridization histochemistry in the brain of developing and mature rats. SHIP2 mRNA was first detected in the ventricular germinal zone at embryonic stages. As the postnatal development proceeded, the expression signal was evident in cell of the white matters, presumptive oligodendrocytes, and no significant expression was seen in neurons throughout the development.

Aging↗