Biomedical subjects

K Hidaka

Publications and source records attributed to K Hidaka.

At least 55 records · Page 3Linked to original sources

PubMed1997

Neutrophil-induced endothelial cell damage: inhibition by a 14-membered ring macrolide through the action of nitric oxide.

Macrolide antibiotics have been used worldwide for about 40 years. The clinical effectiveness of oral erythromycin for diffuse panbronchiolitis has been established and erythromycin seems to act not only as an antibacterial but also as an anti-inflammatory agent. We investigated the effect of 14-membered ring macrolides, erythromycin and clarithromycin, on human neutrophil functions and endothelial cell damage induced by neutrophils. The superoxide production of neutrophils and Ca2+ influx into neutrophils induced by N-formyl-methionyl-leucyl-phenylalanine was inhibited by treatment with erythromycin but not by treatment with clarithromycin. When endothelial cells were cocultured with neutrophils, nitric oxide (NO) presumably released from endothelial cells were enhanced by treatment with erythromycin but not by treatment with clarithromycin and endothelial cell injury induced by neutrophils was ameliorated by addition of erythromycin but not by clarithromycin. The reduction of neutrophil-induced endothelial cell injury by erythromycin was abolished by treatment with carboxy-PTIO which traps NO in the medium. Moreover, nitrite in the medium in which endothelial cells were incubated with neutrophils was enhanced by treatment with erythromycin and the enhancement of nitrite by erythromycin was partially cancelled by addition of H-89, an inhibitor of cyclic AMP-dependent protein kinase (PKA). Erythromycin seems to ameliorate neutrophil-induced endothelial cell injury by affecting not only neutrophil functions but the release of NO from endothelial cells through the action of PKA. The usefulness for the treatment of diseases worsened by the interaction between neutrophils and endothelium might be different among 14-membered ring macrolides.

Anti-Bacterial Agents↗

PubMed1997

The role of nitric oxide in human pulmonary artery endothelial cell injury mediated by neutrophils.

Human endothelial cells are injured by the action of leukocytes. We investigated the role of nitric oxide (NO) in the induction of injury to human pulmonary artery endothelial cells. NO has been a putative source of cytotoxic reactive oxygen species in some settings. Incubation of endothelial cells with neutrophils increased the release of lactate dehydrogenase activity and preloaded fura-2 from endothelial cells, indicating that neutrophils induce endothelial cell injury. This effect was augmented by treatment with carboxy-PTIO, which traps NO in the medium, or with L-NAME, an inhibitor of NO synthase. When endothelial cells were incubated with neutrophils stimulated by phorbol myristate acetate, an activator of protein kinase C, endothelial cell damage was further enhanced and the amount of NO in the medium was decreased. Dibutyryl cyclic AMP, a cell-permeable analogue of cyclic AMP, protected against neutrophil-induced endothelial cell injury and increased NO release into the medium. The effects of dibutyryl cyclic AMP were abrogated by treatment with H-89, a potent inhibitor of cyclic AMP-dependent protein kinase. The protective effect on neutrophil-induced endothelial cell injury by dibutyryl cyclic AMP was abolished by addition of carboxy-PTIO or L-NAME. Thus, our studies suggest that NO, presumably released from endothelial cells, protects against endothelial injury by activated neutrophils and the protective effect by cyclic AMP during coculture with activated neutrophils is mediated through the action of NO. However, when monocytes activated by lipopolysaccharide and IFN-gamma were used instead of neutrophils, endothelial cells were likewise injured, but a much higher level of NO was detected and injury was diminished by addition of carboxy-PTIO to the medium. These observations suggest that the high levels of NO released by activated monocytes contribute to endothelial injury, whereas low levels of NO protect endothelial cells against injury by neutrophils.

Benzoates↗

PubMed1997

[Intrapulmonary hematoma diagnosed by magnetic resonance imaging].

We report a case of intrapulmonary hematoma in which magnetic resonance imaging was useful in establishing the diagnosis. A 53-year-old man had bronchial asthma that was well controlled with inhaled beclomethasone dipropionate and salbutamol, and with oral theophylline. A spherical mass was found in the right lower lung field on a chest radiograph taken during a regular physical examination. A CT scan showed a well circumscribed spherical mass, which was attached to an intrapulmonary bullae. Magnetic resonance imaging showed a well-circumscribed mass in the superior segment of the right lower lobe. On a T1-weighted image the mass was hyperintense and had a higher-intensity rim. On a T2-weighted image the mass was hyperintense and had some hypointense areas. We therefore diagnosed intrapulmonary hematoma. Chest radiography 6 months later revealed a substantial decrease in the size of the mass, which supported the diagnosis. As in this case, intrapulmonary hematoma can be difficult to diagnose because of the lack of a history of injury and because of the slow regression. In this case, magnetic resonance imaging was useful in making the diagnosis.

Hematoma↗

PubMed1996

Low stringency hybridization study of the dopamine D4 receptor revealed D4-like mRNA distribution of the orphan seven-transmembrane receptor, APJ, in human brain.

We recently reported that the density of mRNA for the dopamine D4 receptor was extremely low in human cerebral cortex but unexpectedly higher in the corpus callosum and spinal cord both of which contain substantial white-matter area. Under low stringency conditions, Northern blot analysis using the D4 probe detected cross-hybridized mRNAs having a similar distributional profile to the D4 mRNA in human brain regions, suggesting the mRNA distributional profile is not peculiar to the D4 receptor. Homology screening revealed one of the mRNAs to be an orphan seven-transmembrane receptor, APJ, abundantly expressed in the corpus callosum and spinal cord. In porcine spinal cord the APJ mRNA was detected at a higher level in white-matter rather than in gray-matter area. These data suggest that a group of seven-transmembrane receptors, including the D4 and APJ receptor, is preferentially expressed in the white-matter area probably in non-neuronal glial cells.

Animals↗

PubMed1996

YM-50001: a novel, potent and selective dopamine D4 receptor antagonist.

We investigated some in vitro pharmacological properties of a novel human dopamine D2-like receptor antagonist, YM-50001 [(R)-5-chloro-4-cyclopropylacarbonylamino-2-methoxy-N-[1-(3-methox ybenzyl)- 3-pyrrolidinyl]benzamide monooxalate]. Receptor binding studies revealed that YM-50001 had a potent affinity for human D4 receptors (Ki = 5.62 nM). YM-50001 displayed weak or negligible affinity for other neurotransmitter receptors including human D2 and D3 receptors. YM-50001 shifted the dopamine response curve on each human D2-like receptor subtype-mediated low-Km GTPase activity to the right. YM-50001 also exhibited good D4 selectivity with respect to D2-like receptor antagonism in the functional assay. These results indicate that YM-50001 is a novel, potent and selective D4 receptor antagonist.

Benzamides↗

PubMed1996

Application of capillary gel electrophoresis to the diagnosis of the aldehyde dehydrogenase 2 genotype.

This study dealt with the application of capillary gel electrophoresis (CGE) to diagnosis of the aldehyde dehydrogenase 2 (ALDH-2) genotype. Electrophoresis was performed on a low cross-linked polyacrylamide gel ¿3% T [g acrylamide+g Bis (N,N'-methylenebisacrylamide)], 0.5% C (g Bis/% T)¿ in 100 mM Tris-borate buffer (pH 8.3) at -10 kV with on-column UV detection (260 nm). During the PCR reaction, DNA from the wild-type allele generated a MboII restriction site, which is an amplification created restriction site. This did not occur, however, with DNA fragments from the mutant allele. Therefore, determination of the heterozygous genotype, the coexistence of wild-type and mutant alleles, was easily possible. Analysis of the MboII restriction digests of the PCR products was completed in less than 20 min, showing two peaks corresponding to fragments of 125 (cleaved) and 135 (uncleaved) base pairs (bp), respectively. On the other hand, determination of the homozygous genotype, wild-type or mutant, was difficult in one electrophoresis run. The CGE of the MboII restriction digests gave a single peak and the identification, cleaved or uncleaved, was difficult under our experimental conditions. However, the addition of aliquots of the PCR reaction mixture to the restriction digests, followed by re-electrophoresis, allowed successful diagnosis, yielding two peaks (cleaved and uncleaved) for the wild-type and one peak (uncleaved) for the mutant allele. This study demonstrated that CGE offers a high-speed, high-resolution analytical tool for determining genetic types, as compared with the conventional slab gel methodologies.

Aldehyde Dehydrogenase↗

PubMed1996

Dopamine D3 and D4 receptor antagonists: synthesis and structure--activity relationships of (S)-(+)-N-(1-Benzyl-3-pyrrolidinyl)-5-chloro-4- [(cyclopropylcarbonyl) amino]-2-methoxybenzamide (YM-43611) and related compounds.

In this study, we synthesized a series of (S)-N-(3-pyrrolidinyl)benzamide derivatives, 1, 2a-d, 5a-1, and 7, and their enantiomers, (R)-1 and (R)-5c-e, and evaluated their binding affinity for cloned dopamine D2, D3, and D4 receptors and their inhibitory activity against apomorphine-induced climbing behavior in mice. The results indicate that D2, D3, and D4 receptors have different bulk tolerance (D4 > D3 > D2) for the substituent of the 4-amino group (R1) on the benzamide nuclei and that cyclopropyl-, cyclobutyl-, and cyclopentylcarbonyl groups likely possess adequate bulkiness with respect to D3 and D4 affinity and selectivity over D2 receptors in this series. The results also suggested that the N-substituent (R2) on the pyrrolidin-3-yl group performs an important role in expressing affinity for D2, D3, and D4 receptors and selectivity among the respective subtypes. One of the compounds, (S)-(+)-N-(1-benzyl-3-pyrrolidinyl)-5-chloro-4-[(cyclopropylcarbonyl+ ++) amino]-2-methoxybenzamide (5c) (YM-43611), showed high affinity for D3 and D4 receptors (Ki values of 21 and 2.1 nM, respectively) with 110-fold D4 selectivity and 10-fold D3 preference over D2 receptors and weak or negligible affinity for representative neurotransmitter receptors. Compound 5c displayed potent antipsychotic activity in inhibiting apomorphine-induced climbing behavior in mice (ED50 value, 0.32 mg/kg sc).

Animals↗

PubMed1996

Association of the Est1 protein with telomerase activity in yeast.

The est1 mutant was previously identified because it is defective in telomere maintenance and displays a senescent phenotype. To see if Est1 might be a component of yeast telomerase, we examined immunoprecipitated Est1. The yeast telomerase RNA Tlc1 specifically coprecipitated with Est1. Furthermore, the Est1 immunoprecipitates contained a telomerase-like activity. As expected for yeast telomerase, the activity elongated telomeric primers, it required dGTP and dTTP but not dATP or dCTP, and it was sensitive to RNase A. Further evidence suggesting that the activity was telomerase was obtained from experiments using a TLC1-1 mutant strain, which has a mutant telomerase template containing dG residues. The activity immunoprecipitated from TLC1-1 mutant strains incorporated 32P-labeled dCTP, while activity from TLC1 strains did not. Use of different telomeric primer substrates revealed two distinguishable telomerase-like activities: one was dependent on TLC1, and one was not. The TLC1-independent activity may be due to a second yeast telomerase RNA, or it may be some other kind of activity.

Amino Acid Sequence↗

PubMed1996

Modulatory effect of roxithromycin on human neutrophil function.

Neutrophils are thought to play a key role in tissue injury. We investigated the effect of roxithromycin, a 14-membered ring macrolide, on human neutrophil functions. The drug inhibited N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide (O2-) production and Ca2+ influx of human neutrophils. The inhibition was overcome by adding an inhibitor of cyclic AMP-dependent protein kinase (PKA), H-89. These results suggest that the drug affects O2- production and intracellular Ca2+ concentration of neutrophils via the action of PKA. Moreover, roxithromycin ameliorated endothelial cell injury induced by neutrophils, which may be, in part, due to the effect of the drug on neutrophils. Thus, roxithromycin may contribute to the treatment of diseases worsened by the excessive action of neutrophils.

Anti-Bacterial Agents↗

PubMed1996

Biochemical profile of YM992, a novel selective serotonin reuptake inhibitor with 5-HT2A receptor antagonistic activity.

YM992, (S)-2-[[(7-fluoro-4-indanyl)oxy]methyl]morpholine monohydrochloride, exhibited the biochemical profile of a selective serotonin (5-HT) reuptake inhibitor (SSRI) with 5-HT2A receptor antagonistic activity. YM922 showed the same high affinity as fluoxetine against the 5-HT reuptake site (Ki = 21 nM) and a similar affinity to that of crazodone against the 5-HT2A receptor (Ki = 86 nM). In other receptor binding studies, an affinity for the adrenergic alpha 1 receptor (Ki = 200 nM) and 5-HT2C receptor (Ki = 680 nM) was observed. In a monoamine uptake study, YM992 showed a selective 5-HT uptake inhibition (IC50 = 0.15 microM), but only very weakly inhibited both noradrenaline (NA) and dopamine (DA) uptake (IC50 = 3.1 microM (NA), > 10 microM (DA)). YM992 was also found to potently inhibit the aggregation of human platelets (IC50 = 1.9 microM), revealing antagonistic activity for the 5-HT2A receptor in vitro. Enhanced serotonergic neurotransmission, in particular that mediated by the 5-HT1A receptor, has recently been reported to be important in the long-term treatment of depressive disorders with antidepressants. In addition, some 5-HT1A receptor-mediated responses are known to be potentiated by co-administration of 5-HT2A receptor antagonists. Thus, YM992, having both selective 5-HT reuptake inhibition and 5-HT2A antagonistic activity, might show potent therapeutic activity as a novel antidepressant in comparison with conventional SSRIs.

Animals↗

PubMed1996

Low levels of mRNA for dopamine D4 receptor in human cerebral cortex and striatum.

Significant densities of mRNA for the dopamine D4 receptor in cerebral cortex, particularly in frontal lobe, have been reported in rats and monkeys, supporting the D4 hypothesis in the pathology of schizophrenia. Using northern blot analysis and the competitive reverse transcription-polymerase chain reaction (RT-PCR) method, we determined the relative levels of D4 mRNA in human brain regions to clarify whether the cortical level is also higher in humans. Northern blot analysis revealed an unexpected profile of D4 mRNA in the brain. The detected mRNA size, 1.5 kb, was quite different from the 5.3 kb reported in human neuroblastoma SK-N-MC cells. Higher levels of D4 mRNA were detected not only in the mesolimbic system but also in the corpus callosum, spinal cord, medulla, and subthalamic nucleus. It was surprising that in the cerebral cortex regions as well as the striatum, D4 mRNA was hardly detected. The competitive RT-PCR revealed these relative densities to be at least three orders of magnitude lower than that of the striatal D2 receptor. Our results demonstrate a remarkable difference in cortical D4 mRNA density in humans compared with that in rats and monkeys. Furthermore, the mRNA distribution suggests that the higher density of D4-like binding sites reported recently in normal human striatum is not due to the D4 receptor.

Blotting, Northern↗

PubMed1996

In vitro pharmacological profile of YM-43611, a novel D2-like receptor antagonist with high affinity and selectivity for dopamine D3 and D4 receptors.

1. We investigated some neurochemical properties of a novel benzamide, YM-43611, [(S)-N-(1-benzyl-3-pyrrolidinyl)-5-chloro-4-cyclopropylcarbonylamino+ ++-2- methoxybenzamide] in comparison with putative D2-like receptor antagonists using both rat and human cloned dopamine D2-like receptors in vitro. 2. Receptor binding studies revealed that YM-43611 had appropriately potent affinities for both rat and human D2-like receptors, with moderate selectivity for D3 receptors and high selectivity for D4 receptors over D2 receptors (Ki values (nM) for rat receptors: D2, 165; D3, 35.5; D4, 1.85, and for human receptors: D2, 42.9; D3, 11.2; D4, 2.10). 3. YM-43611 displayed weak or negligible affinity for other neurotransmitter receptors, namely D1, D5, alpha(1), alpha(2), beta, 5-HT1A, 5-HT2A, 5-HT3, H1, M1 and M2 receptors. 4. Dopamine stimulated low-Km GTPase activity on membranes from Chinese hamster ovary (CHO) cells expressing the human D2-like receptor subtype. This response to dopamine of low-Km GTPase activity was inhibited by use of putative D2-like receptor antagonists. YM-43611 showed a moderate selectivity for D3 receptors (Ki = 45.5 nM) and a high selectivity for D4 receptors (Ki = 3.28 nM) over D2 receptors (Ki = 70.6 nM). 5. Dopamine inhibited forskolin-stimulated adenylate cyclase in intact CHO cells expressing the human D2-like receptor subtype. YM-43611 shifted the inhibition curve of dopamine on respective D2-like receptor subtype-mediated cyclic AMP formation to the right in a parallel fashion, showing a pA2 value of 7.42 (38.1 nM) for D2 receptors, a pKB value of 8.06 (8.68 nM) for D3 receptors, and a pA2 value of 8.42 (3.77 nM) for D4 receptors. 6. YM-43611 but not the other D2-like receptor antagonists exhibited good selectivity with respect to dual antagonism for D3 and D4 receptors in both receptor binding and functional assays. 7. These results indicate that YM-43611 is a novel D2-like receptor antagonist with high potency and selectivity for both D3 and D4 receptors. YM-43611 is therefore expected to be valuable in exploration of the physiological role of D3 and D4 receptors.

Animals↗

PubMed1996

[Interstitial pneumonia treated with intermittent cyclophosphamide pulse therapy].

A 52-year-old woman was admitted to the hospital because of polyarthralgia and dry coughing. A chest X-ray film showed bilateral diffuse reticulo-nodular shadows. A specimen obtained by transbronchial lung biopsy revealed alveolar septal thickening and infiltration by mononuclear cells. Interstitial pneumonia associated with rheumatoid arthritis was diagnosed. Interstitial pneumonia relapsed soon after the first pulse of corticosteroid therapy. Cyclophosphamide pulse therapy was given in addition to a second pulse of corticosteroid therapy; 700 mg of cyclophosphamide (500 mg/m2) was administered intravenously every month and the dose of steroids was gradually reduced. Cyclophosphamide pulse therapy was repeated three times and the dose of oral corticosteroids was reduced from 60 mg to 35 mg. There was no bone marrow suppression or hemorrhagic cystitis after the cyclophosphamide pulses. Eventually, corticosteroid therapy was stopped with no clinical deterioration. This case suggests that intermittent cyclophosphamide pulse therapy can be effective for treatment of interstitial pneumonia unresponsive to corticosteroids.

Arthritis, Rheumatoid↗

PubMed1995

The MEF2B homologue differentially expressed in mouse embryonal carcinoma cells.

The MEF2 gene family encodes a MADS-box transcription factor which regulates expression of many muscle-specific genes. We examined the expression of the MEF2 genes in mouse embryonal carcinoma P19 cells before and after in vitro muscle differentiation induced by dimethyl sulfoxide (DMSO). At least three different MADS/MEF2 domains (MEF2A, 2B and 2D) were isolated from P19 cells with the MOPAC technique (mixed oligonucleotides primed amplification of cDNA). Although two of the MADS/MEF2 domain sequences were identical to those of human MEF2A and MEF2D, another domain sequence was similar but not identical to that of human MEF2B. While the transcription of MEF2A and MEF2D was up-regulated during differentiation of P19 cells, the MEF2B homologue was abundantly transcribed in undifferentiated P19, F9 and ES cells and down-regulated in adult heart, skeletal muscle or brain, suggesting that the murine MEF2B homologue might have a function distinct from other members of the MEF2 gene family in embryogenesis and development.

Amino Acid Sequence↗

PubMed1995

An inhibitor of cyclic AMP-dependent protein kinase enhances the superoxide production of human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine.

Intact human neutrophils produced superoxide (O2-) by the stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) even when the extracellular Ca2+ was absent (0.56 +/- 0.13 nmol/min per 10(6) cells). The production by fMLP was enhanced more than twice in the presence of the extracellular Ca2+. Moreover, the O2- production by fMLP in the presence of extracellular Ca2+ was enhanced nearly three times by the treatment of cells with H-89, an inhibitor of cyclic AMP-dependent protein kinase (PKA). The enhancement was not observed when the extracellular Ca2+ was depleted from the reaction mixture. In addition, H-89 did not enhance fMLP-induced O2- production of electropermeabilized neutrophils in which the intracellular Ca2+ concentration was fixed to about 100 nM. These observations suggest that not only Ca2+ influx but the inhibition of PKA is necessary for the maximum O2- production by fMLP and that the O2- production is partially suppressed by the activation of PKA induced by fMLP.

Bucladesine↗

PubMed1995

Differential effects of [3H]nemonapride and [3H]spiperone binding on human dopamine D4 receptors.

We compared some binding parameters of [3H]nemonapride and [3H]spiperone in human dopamine D4 (hD4) receptors with three different numbers of tandem repeat units. Although both of the radioligands showed similar affinity constants for each hD4 receptor variant, the maximal number of binding sites labeled by [3H]nemonapride was approximately 1.35-fold higher than that by [3H]-spiperone for all variants. Estimated Ki values for the inhibition of [3H]nemonapride binding by a series of dopaminergic ligands were highly correlated to respective values obtained for the inhibition of [3H]spiperone binding to each hD4 receptor. These results suggest that the hD4 receptor, as shown for the D2 receptor, may exist in multiple molecular forms as a monomer-dimer equilibria, and that [3H]spiperone may discriminate in the multiple molecular forms.

Benzamides↗

PubMed1995

Polymorphic tandem repeats in dopamine D4 receptor are spread over primate species.

The human dopamine D4 receptor has polymorphic tandem repeats in the third cytoplasmic loop. However, these repeats are not present in the rat counterpart. To determine whether the tandem repeats are specific to humans or not, we analyzed genomic DNA sequences for the D4 receptor of six primate species (human, chimpanzee, gorilla, orangutan, macaque, marmoset). Sequencing data revealed that all primates have the 48-bp tandem repeats in the D4 receptor gene. This finding suggests that these repeats originated before the separation of the New World monkey lineage from the Old World monkey and ape-human lineages.

Amino Acid Sequence↗

PubMed1995

Fine structure of the cilia in the pancreatic duct of WBN/Kob rat.

We observed the cilia in pancreatic ducts (intraductal cilia) with scanning and transmission electron microscopy (SEM and TEM), using male WBN/Kob rats (W/K), which are the spontaneously developed chronic pancreatitis models with stasis of pancreatic juice, and male Wistar rats as control. By SEM observations, the lengths of cilia in interlobular ducts of 18-mo-old W/K were demonstrated to elongate markedly. By TEM observations in the controls, cross-sections of the intraductal cilia were demonstrated to present various numbers of microtubules (those with seven, eight, or nine microtubules accounted for 83.3% of all). There was no significant difference between W/K and controls in the number of microtubules in the cross-sections of intraductal cilia: the intraductal cilium core was provided with nine microtubules, which were different from the number of microtubules encountered within the cilium core of other ciliated cell (i.e., bronchial epithelium, and so forth), and their number in the cross-section of intraductal cilium decreased at a distal portion. Though some of their cross-sections revealed deformities of ciliary membranes and disarrangements of microtubular complex, there was no significant difference in their incidence between both rats. These findings suggest that the intraductal cilia have different functions from the ciliated cells' cilia, and W/K has the elongated intraductal cilia without internal structural change.

Animals↗