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Y Kohno

Publications and source records attributed to Y Kohno.

At least 145 records · Page 8Linked to original sources
PubMed1996

Induction of apoptosis in HL-60 human promyelocytic leukemia cells by adenosine A(3) receptor agonists.

The effects of adenosine (ADO) analogs on cells of the human promyelocytic HL-60 line were examined. ADO A(3) receptor agonists, N(6)-(3-iodobenzyl)adenosine-5'-N-methylcarboxamide (IB-MECA, 30-60 microM) and 2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (CI-IB-MECA, 10-30 microM) induced apoptotic cell death. In contrast, neither an A(1)/A(2) antagonist (XAC) nor other selective ADO receptor agonists (CPA, NECA and CGS21680) induced apoptosis at concentrations of <30 microM. Both IB-MECA and CI-IB-MECA significantly induced Ca(2+) release from intracellular Ca(2+) pools followed by Ca(2+) influx, suggesting the presence of phospholipase C-coupled ADO A(3) receptors on HL-60 cells. This was further supported by the presence of mRNA of ADO A3 receptor in the cells. These results suggest that activation of ADO A(3) receptors is responsible for the ADO-induced apoptosis in HL-60 cells and could be of potential therapeutic value in the treatment of leukemia.

Adenosine↗
PubMed1996

Stereoselective pharmacokinetics of [14C]-labeled KE-298, a new anti-rheumatic drug, in rats.

The stereoselective pharmacokinetics of two enantiomers of [14C]-labeled KE-298 [2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanonic acid] were investigated in rats. The blood levels of radioactivity after the oral administration of (+)-(S)-[14C]KE-298 were higher than that for (-)-(R)-[14C]KE-298; the AUC of the former was approximately twice that of the latter. No significant stereoselectivity was observed in absorption rate. The tissue/ plasma level ratios at 30 min after oral administration of (-)-(R)-[14C]KE-298 in the liver and kidney, the major metabolic and/or excretory organs, were 2 to 3 times higher than those for (+)-(S)-[14C]KE-298. Neither was evidence of stereoselectivity found in the excretion of radioactivity. During incubation with isolated rat hepatocytes in vitro, the metabolic rates of KE-298 enantiomers were not significantly different. Plasma protein binding 20 min after the oral administration of (+)-(S)-[14C]KE-298 and (-)-(R)-[14C]KE-298 was 99.3% and 97.0% respectively. Comparing the unbound fraction, (-)-(R)-[14C]KE-298 was approximately 4 times higher than (+)-(S)-[14C]KE-298. In order to make clear the relationship between stereoselective pharmacokinetics and protein binding for [14C]KE-298, the comparative pharmacokinetics of (+)-(S)-[14C]KE-298 and (-)-(R)-[14C]KE-298 were investigated in analbuminemic rats. In these animals, no evidence of stereoselectivity was found for either blood level-time profiles or plasma protein binding. These results revealed that the stereoselective pharmacokinetics of KE-298 in rats might be due to enantiomeric differences in binding to plasma albumin.

Animals↗
PubMed1996

5-HT3 receptor blocking properties of the antiparkinsonian agent, talipexole.

1. Talipexole showed moderate displacement activity of 3H-GR 65630 binding to 5-HT3 receptors in both rat cortical and intestinal membrane fractions with Ki values of 0.35 microM and 0.22 microM, respectively. 2. Bromocriptine failed to displace the binding activity in either experimental system even at a concentration of 10 microM. 3. Both talipexole and tropisetron were found to significantly inhibit 5-HT3 receptor-mediated effects of 5-HT in isolated guinea-pig ileum or atrium; however, the effect of talipexole was weaker than that of tropisetron. 4. Bromocriptine, in contrast, had no antagonistic effects on 5-HT3 receptor-mediated activity in guinea-pig ileum or atrium. 5. It was concluded that talipexole might act as an antagonist on 5-HT3 receptors in both brain and intestinal tissues.

Animals↗
PubMed1996

Estimation of coronary flow reserve with the instantaneous coronary flow velocity versus pressure relation: a new index of coronary flow reserve independent of perfusion pressure.

Our goal was to develop a new method to evaluate coronary flow reserve independent of perfusion pressure by equipping dogs with a Doppler flow probe in the left anterior descending artery. The slope of the linear portion of the velocity-pressure loop in the late diastolic phase was defined as VP slope; the hyperemic:basal ratio of the VP slope was defined as VP slope ratio, and the hyperemic:basal ratio of the mean coronary blood flow velocity was defined as coronary flow reserve (CFR). We measured VP slope ratio and CFR, altering aortic pressure by aortic banding and inferior vena cava occlusion. VP slope ratio was independent of aortic pressure, but CFR increased with increments in aortic pressure. The VP slope ratio and CFR decreased in the presence of coronary stenoses. In conclusion, VP slope ratio is considered to be a physiologic index of the severity of coronary stenosis, which is independent of perfusion pressure. This measure is easily applicable in clinical practice.

Angioplasty, Balloon, Coronary↗
PubMed1996

Establishment and characterization of alpha s1-casein-specific T-cell lines from patients allergic to cow's milk: unexpected higher frequency of CD8+ T-cell lines.

To study cow's milk allergy at the cellular level, we assessed the reactivity of peripheral blood mononuclear cells from patients allergic to cow's milk to alpha s1-casein, which is one of the major allergens in cow's milk. Proliferation of the cells to alpha s1-casein activation showed a rather weak response. Therefore to understand T-cell reactivity to alpha s1-casein in more detail, we prepared alpha s1-casein-specific T-cell lines from patients allergic to cow's milk and established 26 T-cell lines. These T-cell lines could be classified into three groups by analyzing their surface marker expression: those containing predominantly CD4+ CD8- T cells, those containing both CD4+CD8- and CD4-CD8+ T cells, and those containing predominantly CD4- CD8+ T cells. The CD8+ T cells were obtained at an unexpectedly higher frequency from the patients. These T-cell lines produced interferon-gamma and IL-4. These results suggest that CD8+ T cells specific for alpha s1-casein and CD4+ T cells were primed by the stimulation with alpha s1-casein in patients allergic to milk and that both T cells may play a key role in the onset, progression of, or recovery from cow's milk allergy.

CD8-Positive T-Lymphocytes↗
PubMed1996

Diminished interferon-gamma (IFN-gamma) production by bacterial antigen-specific T cells in atopic patients.

In this study, we established and studied cytokine production of T cell lines (TCL) specific to either a purified protein derivative of Mycobacterium tuberculosis (PPD) or Dermatophagoides farinae (Df) from atopic patients and non-atopic healthy subjects. IFN-gamma was detected in the culture supernatants of all of 36 PPD-specific TCL established from healthy controls, whereas only 24 of 38 PPD-specific TCL from patients produced IFN-gamma. Furthermore, the amounts of IFN-gamma produced by PPD-specific TCL from patients were significantly lower than those from healthy controls. No IL-4 was detected in any PPD-specific TCL from either healthy controls or atopic patients. The amounts of IL-4 production from Df-specific TCL from atopic patients were much higher than from healthy controls, while few TCL produced IFN-gamma. These results suggest that the skewing to the Th2-type T cell response in atopic patients is a response not only to allergens, but also to bacterial antigens, compared with non-atopic subjects. Activation of PPD-specific TCL from patients with calcium ionophore A23187 plus phorbol myristate acetate resulted in much higher IFN-gamma production than in TCL established from healthy controls, indicating that the low production of IFN-gamma by PPD-specific T cells from atopic patients is not due to an intrinsic T cell defect but to some regulatory mechanisms.

Animals↗
PubMed1996

Sequence and expression patterns of mouse SPR1: Correlation of expression with epithelial function.

A final event in the terminal differentiation of stratified squamous epithelia is the formation of a cornified cell envelope, which is a complex of several proteins cross-linked together by transglutaminases. One set of proteins is the family of small proline rich (SPR) proteins. In human foreskin epidermal cell envelopes, SPRs serve as cross-bridging proteins among the more abundant loricrin. In order to study further their evolution and expression, we have isolated and sequenced cDNAs encoding two mouse SPR1 proteins, SPR1a and SPR1b Comparative sequence analysis showed the preservation of the overall structure of mammalian SPR1 proteins with highly conserved termini and a central peptide domain repeated 13 (SPE1a) or seven (SPR1b) times. Tissues obtained from mouse fetal, newborn, and adult skin were tested by Northern blot analyses, in situ hybridization and immunohistochemistry using an antibody raised to a synthetic peptide corresponding to the C terminus of the SPR1a protein. Skin expression was first detected in fetal periderm in anagen hair follicles of newborn and older mice, and in the thickened epidermis of the lip and footpad, but no signal was detected in interfollicular trunk epidermis. High levels of SPR1a expression were found in epithelia from the forestomach and penis, and in benign squamous papillomas. Other epithelia expressing SPR1a include the tongue, esophagus, and vagina. Whenever detected, SPR1a positive staining was present in the spinous and granular layers. In the forestomach and papillomas, the periphery of cells in the cornified layer was also stained. Our results suggest that SPR1a participates widely in the construction of cell envelopes in cornifying epithelia characterized by either increased thickness or a requirement for extreme flexibility. Based on its likely function as a cross-bridging protein in cell envelopes, we conclude that the mechanical attributes of cell envelopes may be determined in part by the SPR1 content, in accordance with the specific function of the epithelium.

Animals↗
PubMed1996

Allergenic epitopes of ovalbumin (OVA) in patients with hen's egg allergy: inhibition of basophil histamine release by haptenic ovalbumin peptide.

We studied allergenic determinants that induce hypersensitivity to OVA, the major allergen in egg allergy, using immunoblot and histamine release assays. Immunoblot analysis demonstrated a part of the OVA epitope was in the C-terminal region comprising residues 347-385 (OVA347-385). Histamine was released from basophils of a patient with egg allergy upon stimulation with the OVA fragment corresponding to OVA347-385. Furthermore, detailed epitope mapping using overlapping peptides (residues 347-366, OVA-A; residues 357-376, OVA-B; and residues 367-385, OVA-C) in the OVA 347-385 region was carried out using the histamine release assay. In order for histamine release from basophils to occur, the allergen must possess two or more allergenic determinants located on the protein molecule at distances that would be equivalent to the distances between IgE molecules on the membrane surface. these results suggest that there are at least two epitopes that bind IgE antibodies on each OVA peptide. In addition, one epitope that binds IgE antibodies in two patients appears to reside in the haptenic peptide OVA357-366 (OVA-B1). The histamine release from basophils stimulated by OVA-B was completely inhibited by OVA-B1 in one of these patients. Similarly, OVA-B1 inhibited the histamine release produced by OVA-A in the other by more than 40%. These results suggest that haptenic synthetic peptides could regulate the allergic reaction in the effector phase if common epitope(s) recognized by IgE antibodies in the patients with egg allergy can be found. These are the first studies that provide an antigen-specific approach to inhibiting histamine release from basophils by a haptenic peptide recognized by IgE antibodies in an allergic disorder.

Allergens↗
PubMed1996

Establishment and characterization of ovalbumin-specific T cell lines from patients with egg allergy.

In order to investigate T cell recognition of allergens in hen egg allergy, we have established 30 ovalbumin (OVA)-specific T cell lines (TCLs) from peripheral blood mononuclear cells of 6 patients with atopic dermatitis, who are positive for IgE antibodies to OVA and clinically allergic to hen egg, and characterized them for their cytokine production pattern. All TCLs we could study were mainly composed of CD4+ T cells. Most TCLs produced significant amounts of interleukin 4 (IL-4) and IL-5 but no or very little interferon gamma on antigen stimulation, suggesting that these TCLs belong to TH2-type T cells. Restriction elements and epitope specificities were further studied on some TCLs. Antibody blocking of the proliferative responses of the TCLs to OVA indicated that HLA-DR are acting as the dominant restriction elements for these TCLs with minor contribution of HLA-DQ. By use of 187 overlapping synthetic peptides covering the whole sequence of OVA, at least 3 different T cell epitopes were identified.

Allergens↗
PubMed1996

Identification of metabolites of KE-298, a new antirheumatic drug, and its physiological properties in rats.

To characterize the pharmacokinetic properties of a new antirheumatic drug, KE-298, the metabolic fate of [14C]labeled KE-298 in rats was investigated, focussing especially on the identification of metabolites and its physiological properties. [14C]KE-298 was rapidly and almost completely absorbed after oral administration, and was well distributed throughout the body. In plasma, only a small amount of unchanged KE-298 was detected and the major component was an active metabolite, deacetyl-KE-298, which accounted for approximately 50% of the radioactivity in the plasma. Further evidence was obtained by 1H-NMR analysis that deacetyl-KE-298 existed as ketone-thiol and thiohemiacetal forms in a tautomeric equilibrium. As the second main metabolite in plasma, S-methyl-KE-298, a methyl conjugate of deacetyl-KE-298, was detected. Neither deacetyl-KE-298-amino acid mixed disulfide nor any disulfide of the drugs was found. Though a thiol-containing drug generally remains in the body due to the formation of mixed disulfide with protein, no evidence of retained radioactivity was found in any tissues after the administration of [14C]KE-298. Further, in the ex vivo studies of plasma protein binding, the formation of drug-protein conjugate was scarcely detected. These results suggest that the metabolic pattern of deacetyl-KE-298 is different from that of common thiol-containing drugs, and that the reactivity of the thiol moiety of deacetyl-KE-298 to protein is extremely low. This property of deacetyl-KE-298 may be principally responsible for the nonaccumulation of radioactivity in the tissues after the administration of [14C]KE-298.

Animals↗
PubMed1996

General pharmacology of the new non-xanthine adenosine A1 receptor antagonist (+)-(R)-[(E)-3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)acryloyl]-2- piperidine ethanol.

FK 453 ((+)-(R)-[(E)-3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl) acryloyl]-2-piperidine ethanol, CAS 121524-18-3) is a potent non-xanthine adenosine A1 receptor antagonist with diuretic and renal vasodilatory activity. The general pharmacology of FK 453 was investigated in mice, rats, guinea-pigs and dogs. In in vivo tests, FK 453 had little effect on the central nervous system (general behaviour, spontaneous motor activity, potentiation of barbiturate anesthesia, anticonvulsant activity, analgesic activity and body temperature), hematological system (bleeding time, coagulation time and recalcification time) and intestinal charcoal transit. FK 453 also did not show any cardiovascular (blood pressure, heart rate and femoral blood flow) or respiratory effects. In in vitro tests, although FK 453 had little effect on noradrenaline-induced contraction in rat vas deferens and histamine-induced contraction in guinea-pig trachea, FK 453 inhibited the acetylcholine-, histamine- and barium-induced contraction in isolated guinea-pig ileum and serotonin-induced contraction in isolated rat stomach. FK 453 also exerted significant inhibitory activity on collagen- and U 46619-induced platelet aggregation. However these effects of FK 453 on isolated tissue and platelet were observed only at high concentrations. These results suggest that FK 453 possesses a selective pharmacological profile, and one promising therapeutic site for this drug is in the kidney.

Analgesics↗
PubMed1996

[Dynamic MR and fat suppression imaging of pancreatic carcinoma].

The usefulness of dynamic MR and fat suppression imaging was investigated in 19 patients with pancreatic duct cell carcinoma. In addition to conventional spin echo imaging, dynamic MR and fat suppression imaging were performed. These images were evaluated for the detectability of lesions. The detectability of lesions was classified as good, fair or poor. On T1 weighted images, 26% of cases were evaluated as "good" and 32% as "fair". On dynamic MRI, 69% of cases were evaluated as "good" and 26% of cases as "fair". On pre- and postcontrast fat suppression images, 32% and 28%, respectively, were evaluated as "good", and 47% and 39% as "fair". Neither T2 weighted images nor enhanced T1 weighted images were useful. Direct comparison between dynamic MR and fat suppression images was also done. In 42% of cases, dynamic MR was superior to fat suppression images and in 42%, dynamic MRI was equal to fat suppression. In 16% of cases, fat suppression was superior to dynamic MRI. It was concluded that dynamic MR and fat suppression imaging were more useful than conventional spin echo imaging for the detection of pancreatic carcinoma.

Aged↗
PubMed1995

Species differences in hydrolysis of isocarbacyclin methyl ester (TEI-9090) by blood esterases.

Species differences in the hydrolysis of isocarbacyclin methyl ester (TEI-9090) in whole blood and in its separated components were studied in rats, dogs and human. Esterase activity in rat whole blood was approximately 100 and 400 times higher than that in dog and human whole blood, respectively, and was attributed to high plasma activity. In contrast, TEI-9090 hydrolysis activities in dog and human blood were due to red blood cells (RBC), whose activity in humans was slightly suppressed by albumin. In dogs, activity in RBC membranes was 10 times greater than in the cytosol, while in human membrane and cytosol activity was virtually the same. The effects of the esterase inhibitor diisopropylfluorophosphate, bis-p-nitrophenylphosphate (BNPP), eserine, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) and p-chloromercuribenzoate showed that the rat plasma and RBC cytosol esterases hydrolysing TEI-9090 were carboxylesterase (CarbE) and arylesterase (ArE), respectively. The esterases in dog plasma and RBC membrane were CarbE, and RBC cytosol esterase was ArE. In humans, the esterase activities in plasma, RBC membrane and cytosol were butyrylcholinesterase, CarbE and ArE, respectively.

Animals↗
PubMed1995

Kinetic study of quenching reaction of singlet oxygen and scavenging reaction of free radical by squalene in n-butanol.

The rate constant of quenching of singlet oxygen (kQ) by squalene (SQ) is found to be much larger than those of the lipids in human skin surface. SQ is the first target lipid in human skin surface by oxidative stresses such as sun light exposure. kQ of SQ is similar to that of 3,5-di-t-butyl-4-hydroxytoluene (BHT). The large kQ of SQ is due to the small ionization potential. SQ consists of six 2-methyl-2-pentene units and kQ of SQ is about 6-times as large as that of 2-methyl-2-pentene. The electron donating property of methyl groups bonded to quaternary carbons of SQ is essential to the large kQ. SQ is not very susceptible to peroxidation and is stable for attacks by peroxide radicals. The chain reaction of lipid peroxidation is unlikely to be propagated with SQ in human skin surface. It is concluded that SQ functions as an efficient quencher of singlet oxygen and prevents the corresponding part of lipid peroxidation in human skin surface.

1-Butanol↗
PubMed1995

Action of intravenously administered talipexole on the rat striatal neurons receiving excitatory input from nigral dopamine neurons.

Electrophysiological studies using rats anesthetized with chloral hydrate were performed to elucidate whether or not intravenously injected talipexole acted as a D2 receptor agonist on the striatal neurons in comparison with the action of bromocriptine. The activities of the striatal neurons were extracellularly recorded using a glass microelectrode attached along a seven-barreled micropipette, each barrel of which was filled with talipexole, bromocriptine, SCH23390 (D1 antagonist), domperidone (D2 antagonist), glutamate or 2 M NaCl. These drugs were iontophoretically applied to the immediate vicinity of the target neuron being recorded. The effects of talipexole and bromocriptine were examined on the neurons, whose spikes (induced by the stimulation of the substantia nigra pars compacta) were inhibited by the iontophoretic application of domperidone. Iontophoretic application of talipexole or bromocriptine increased spontaneous firing of these neurons and this increase in firing was also inhibited by iontophoretically applied domperidone. In the same neurons, intravenously administered talipexole (0.01, 0.02 and 0.04 mg/kg) dose-dependently increased firing, and this increase was inhibited by microiontophoretically applied domperidone, but not by SCH23390. On the other hand, the intravenous injection of bromocriptine (0.1, 0.2 and 0.4 mg/kg) also increased the firing rate. However, the increase was not dose-dependent and fluctuated; the firing transiently decreased during the increase in firing with intravenously administered bromocriptine. However, the bromocriptine-induced increase in firing was also suppressed by domperidone, and decrease in firing was inhibited by SCH23390. These findings suggest that talipexole acts as a D2 agonist on the striatal neurons receiving input from substantia nigra pars compacta and increases firing when intravenously applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Heterogeneity of neurogenic responses in intra- and extrameningeal arteries of dogs.

1. Neurogenic responses to transmural electrical stimulation were examined in endothelium-denuded extrameningeal (vertebral and carotid) and intrameningeal (spinal, basilar and middle cerebral) arteries isolated from dogs. 2. In the extrameningeal arteries, transmural electrical stimulation produced a phasic contraction. This contraction was abolished by tetrodotoxin, prazosin and guanethidine. However, alpha,beta-methylene ATP and NG-nitro-L-arginine (L-NOARG) had no significant effect on the contractile responses. 3. In the intrameningeal arteries, the neurogenic responses to electrical stimulation were composed of a transient contraction and relaxation. The transient contraction was selectively inhibited by guanethidine L-NOARG abolished the relaxation but not the contraction induced by electrical stimulation. Prazosin had no effect on either neurogenic response. 4. Noradrenaline produced a large contraction in the extrameningeal arteries which was selectively inhibited by prazosin. alpha,beta-Methylene ATP produced neither contraction nor inhibition of the response to noradrenaline in the extrameningeal arteries. 5. In the intrameningeal arteries, alpha,beta-methylene ATP produced a greater contraction than noradrenaline. The response to alpha,beta-methylene ATP was selectively abolished by desensitization of P2x-purinoceptors with alpha,beta-methylene ATP itself. The contractile response to noradrenaline was inhibited by rauwolscine but not by prazosin. 6. ATP produced endothelium-dependent relaxations in the extrameningeal and intrameningeal arteries, which were attenuated by endothelium removal. 7. NADPH diaphorase-positive fibres were dense in the middle cerebral and basilar arteries but rare or absent in the spinal artery. In the extrameningeal arteries diaphorase-positive traces were observed in the vasa vasorum. 8. The present findings indicate that the neurogenic responses of intrameningeal arteries of dogs are composed of NO-ergic and sympathetic purinergic components, while the extrameningeal arteries tested produced only sympathetic adrenergic responses, suggesting that regional heterogeneity may be associated with a sudden transition in innervation and receptor expression at the meninx.

Adenosine Triphosphate↗
PubMed1995

Inhibitory action of nebracetam on various stimuli-evoked increases in intracellular Ca2+ concentrations in cultured rat cerebellar granule cells.

Nebracetam (10-100 microM) dose-dependently inhibited increases in intracellular Ca2+ concentrations evoked by various stimuli in cultured rat cerebellar granule cells. The magnitude of the nebracetam (100 microM)-induced inhibition of L-glutamate- and N-methyl-D-aspartate-evoked Ca2+ responses was 1.5-fold and 1.7-fold greater, respectively, than the inhibition of the high K(+)-evoked response. These findings suggest that in cultured cerebellar granule cells, nebracetam attenuates the external Ca2+ influx derived from the activation of N-methyl-D-aspartate receptor-gated rather than voltage-gated Ca2+ channels.

Animals↗