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Biomedical subjects

Y Kawata

Publications and source records attributed to Y Kawata.

At least 19 recordsLinked to original sources
PubMed2001

Insulin alters heterogeneous nuclear ribonucleoprotein K protein binding to DNA and RNA.

The interaction of the multimodular heterogeneous nuclear ribonucleoprotein (hnRNP) K protein with many of its protein and nucleic acid partners is regulated by extracellular signals. Acting as a docking platform, K protein could link signal-transduction pathways to DNA- and RNA-directed processes such as transcription, mRNA processing, transport, and translation. Treatment of hepatocyte culture with insulin increased K protein tyrosine phosphorylation. Insulin altered K protein interaction with RNA and DNA in vitro. Administration of insulin into mice had similar effects on K protein in liver. Coimmunoprecipitations of RNA with K protein revealed preferential in vivo K protein binding of a subset of transcripts, including the insulin-inducible c-fos mRNA. These results suggest a class of insulin pathways that signal nucleic acid-directed processes that involve K protein.

Animals↗
PubMed2001

Peribronchiolar accumulation of dendritic cells and their close association with CD4(+) T cells in the murine lung hypersensitivity.

In order to understand the interaction between dendritic cells (DCs) and helper T (Th) cells in the region exposed to antigens during pulmonary delayed-type hypersensitivity (DTH), which is considered to be mediated by Th1 cells, we immunohistochemically investigated their spatial relationship in the cellular infiltrate. At 24 hours after intratracheal instillation of hapten in sensitized mice, DCs were preferentially accumulated around the bronchioles, whereas macrophages were more abundant around the accompanying arteries. DCs often formed a cluster, in which they were interconnected with each other by projections. Serial section analysis revealed that clustered DCs made a close apposition to Th cells but much less frequently to cytotoxic T cells and B cells. Immunoelectron microscopy demonstrated that lymphocytes extravasated the capillaries in the peribronchiolar interstitium and made conjugation with DCs. In the interstitial tissue, DCs often adhered to the fibroblasts, suggesting the supportive role of the latter cells in DC migration. Eosinophils were also frequent around the arteries, representing the possible involvement of Th2 cytokines. By contrast, in a chronic type of airway inflammation induced by repeated challenges of aerosolized ovalbumin, DCs were densely and diffusely accumulated around the arteries in the same way as macrophages. The present study demonstrated a close association of DCs with Th cells around the bronchioles during pulmonary DTH, suggesting that local interaction between them in the lung may play important roles in the development of this disorder.

Animals↗
PubMed2001

Adenosine receptor subtypes modulate two major functional pathways for hippocampal serotonin release.

To clarify the mechanisms of interaction between adenosine A(1) receptor (A1-R) and adenosine A(2) receptor (A2-R) on neurotransmitter release, this study determined the functional interactions among adenosine receptors (AD-Rs), voltage-sensitive Ca(2+) channels (VSCCs), protein kinases (PKs), and synaptic proteins [N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptors] on hippocampal serotonin release using in vivo microdialysis in freely moving rat. Basal serotonin release was regulated by two functional complexes: N-type VSCC (N-VSCC)/calcium-phospholipid-dependent protein kinase (PKC)/syntaxin (major pathway) and P-type VSCC (P-VSCC)/cyclic AMP-dependent protein kinase (PKA)/synaptobrevin (minor pathway). However, K(+)-evoked serotonin release was regulated by N-VSCC/PKC/syntaxin (minor pathway) and P-VSCC/PKA/synaptobrevin (major pathway). A1-R antagonists increased basal serotonin release, which was reduced by inhibitors of N-VSCC, PKC, and syntaxin predominantly and by inhibitors of PKA and synaptobrevin weakly, but was not affected by P-VSCC inhibitor. In the presence of A1-R antagonist, A2-R agonists increased basal serotonin release, which was inhibited by inhibitors of P-VSCC, PKA, and synaptobrevin predominantly and reduced by inhibitors of N-VSCC, PKC, and syntaxin weakly. Under the condition of activation of adenylate cyclase in the absence of A1-R antagonists, A2-R agonists increased basal serotonin release. A1-R antagonist and A2-R agonist enhanced K(+)-evoked serotonin release, which was inhibited by inhibitors of P-VSCC, PKA, and synaptobrevin predominantly. These results suggest that an activation of A1-R suppresses serotonin release via inhibition of both N-VSCC/PKC/syntaxin and P-VSCC/PKA/synaptobrevin pathways, and an activation of A2-R stimulates serotonin release via enhancement of the P-VSCC/PKA/synaptobrevin pathway. Therefore, PKA activity plays an important role in the interaction between A1-R and A2-R on hippocampal serotonin release.

Adenylyl Cyclases↗
PubMed2001

Pharmacological discrimination between effects of carbamazepine on hippocampal basal, Ca(2+)- and K(+)-evoked serotonin release.

To elucidate mechanisms of hippocampal serotonin release and possible mechanisms of clinical action of carbamazepine (CBZ), we determined interaction between antagonists of N-type (omega-conotoxin GVIA:GVIA), P-type (omega-agatoxin IVA:IVA) Ca(2+) channels, Na(+) channel (tetrodotoxin: TTX) and CBZ on hippocampal basal, Ca(2+)- and K(+)-evoked serotonin releases, using microdialysis in freely moving rats. Basal release was reduced by TTX, GVIA and IVA (GVIA>IVA). Ca(2+)-evoked release was reduced by GVIA but unaffected by TTX and IVA. K(+)-evoked release was reduced by TTX, GVIA and IVA (GVIA<IVA). TTX inhibited actions of IVA and GVIA on respective basal and K(+)-evoked releases, without affecting Ca(2+)-evoked release. Perfusion with 100 microM CBZ (estimated-concentration in hippocampal tissue: 19+/-2 microM) enhanced basal and Ca(2+)-evoked releases, but reduced K(+)-evoked release, whereas 1000 microM CBZ (estimated-concentration in hippocampal tissue: 188+/-16 microM) reduced three types of releases. Under condition of pretreatment with 100 and 1000 microM CBZ, TTX unaffected basal and K(+)-evoked releases. Under condition of pretreatment with 100 microM CBZ, IVA and GVIA unaffected basal and K(+)-evoked releases, respectively, but GVIA reduced basal, Ca(2+)-evoked releases and IVA also reduced K(+)-evoked release. Under condition of pretreatment with 1000 microM CBZ, GVIA unaffected three types of releases, and IVA unaffected basal release but reduced K(+)-evoked release. These findings contribute towards the possible mechanisms of concentration-dependent antiepileptic action of CBZ, which possibly inhibits Na(+) channel related neurotransmitter release mechanisms during K(+)-evoked stage, and simultaneously enhances N-type Ca(2+) channel related basal serotonin release at the resting stage.

Animals↗
PubMed2001

Determination of effects of antiepileptic drugs on SNAREs-mediated hippocampal monoamine release using in vivo microdialysis.

1. To elucidate possible mechanisms underlying the effects of carbamazepine (CBZ), valproate (VPA) and zonisamide (ZNS) on neurotransmitter exocytosis, the interaction between these three antiepileptic drugs (AEDs) and botulinum toxins (BoNTs) on basal, Ca(2+)- and K(+)-evoked release of dopamine (DA) and serotonin (5-HT) were determined by microdialysis in the hippocampus of freely moving rats. 2. Basal release of monoamine was decreased by pre-microinjection of the syntaxin inhibitor, BoNT/C, but only weakly affected by the synaptobrevin inhibitor, BoNT/B. Ca(2+)-evoked release was inhibited by BoNT/C selectively. K(+)-evoked release was reduced by BoNT/B predominantly and BoNT/C weakly. 3. Perfusion with low and high concentrations of CBZ and ZNS increased and decreased basal monoamine release, respectively. Perfusion with VPA increased basal 5-HT release concentration-dependently, whereas basal DA release was affected by VPA biphasic concentration-dependently, similar to CBZ and ZNS. This stimulatory action of AEDs on basal release was inhibited by BoNT/C predominantly. 4. Ca(2+)-evoked monoamine release was increased by low concentrations of CBZ, ZNS and VPA, but decreased by high concentrations. These effects of the AEDs on Ca(2+)-evoked release were inhibited by BoNT/C, but not by BoNT/B. 5. K(+)-evoked monoamine release was reduced by AEDs concentration-dependently. The inhibitory effect of these three AEDs on K(+)-evoked release was inhibited by BoNT/B, but not by BoNT/C. 6. These findings suggest that the therapeutic-relevant concentration of CBZ, VPA and ZNS affects exocytosis of DA and 5-HT, the enhancement of syntaxin-mediated monoamine release during resting stage, and the inhibition of synaptobrevin-mediated release during depolarizing stage.

Animals↗
PubMed2001

Non-optically probing near-field microscopy with illumination of total internal reflection.

We have developed a non-optically probing near-field microscope with illumination of total internal reflection. Because the illumination light does not pass through the specimens, it is possible to observe thick specimens or highly absorptive materials. It reduces the background noise because the decay length of the evanescent wave is a few hundred nanometres. We found that although in the total internal reflection illumination system the light passed through the photosensitive film and illuminated the specimen, it did not affect the photosensitive film severely and did not limit the resolution. The imaging properties of reflection illumination and transmission illumination are analysed using a finite-differential time domain method.

Journal Article↗
PubMed2001

Sociomedical aspects of epileptic patients: their employment and marital status.

We examined the employment and marital status of adult patients with epilepsy who did not have mental retardation and who had been treated at Hirosaki University Hospital, Hirosaki, Japan, for more than 5 years. The present study included 278 patients (142 males and 136 females) ranging from 20 to 60 years of age. We investigated the occupational status of the subjects and found that 168 had permanent jobs, but 41 patients were unemployed at the time of this survey. The proportion of the patients whose seizures were controlled at the time of this survey was 68% (114/168) in the group having permanent jobs, and 22% (9/41) in the unemployed group. Forty cases answered that they had resigned from their jobs due to occurrence of epileptic seizures. Of these patients, 13 were dismissed and 27 resigned voluntarily due to the potential for seizures. As to relationship between jobs and neuropsychiatric complications, the incidence of a past history of psychotic states in the unemployed group was significantly higher than that in the employed group. As to marital status, 13 males and 16 females (n = 29) had experienced divorce. Seven cases (two males and five females) had answered that epilepsy had been the reason for their divorce. We conclude that epilepsy or epileptic seizures have various negative effects on the patient's social life.

Adult↗
PubMed2001

Appropriate dosing of pilsicainide hydrochloride in patients on hemodialysis.

Appropriate dosing of pilsicainide hydrochloride, an anti-arrhythmic drug excreted via the kidney, was investigated in patients on dialysis. Ten chronic hemodialysis patients with coexisting severe palpitation of supraventricular premature contractions (SVPC) were treated with 25 mg of pilsicainide hydrochloride before dialysis. All of their plasma concentrations were maintained within the therapeutic range and their mean dialysis rate was 32%. After 2 weeks, 7 patients were followed with consecutive daily dose treatment. In 3 of them, the dosage was returned to the single pre-dialysis administration because of the elevated plasma concentration reaching the toxic range 1 month after the start of administration. The dose schedule was maintained, and plasma pilsicainide concentrations remained within the therapeutic range during the 6-month follow-up. No abnormal findings were found in any parameters of electrocardiography, echocardiography or biochemistry. The number of SVPC diminished > 90% compared to the pretreatment level.

Anti-Arrhythmia Agents↗
PubMed2001

Studies on the constituents of Clematis species. VIII. Triterpenoid saponins from the aerial part of Clematis tibetana KUNTZ.

From the aerial part of Clematis tibetana, two new hederagenin 3,28-O-bisdesmosides called clematibetosides A and C, and a new gypsogenin 3,28-O-bisdesmoside called clematibetoside B, have been isolated together with ten known saponins. The structures of the new saponins have been elucidated based on chemical and spectral evidence as follows: clematibetoside A, 3-O-(2-O-caffeoyl)-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyraside; clematibetoside B, 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl gypsogenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside; clematibetoside C, 3-O-beta-D-ribopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside.

Carbohydrate Sequence↗
PubMed2001

[Le Duc-Camey procedure as a method of ureteroileal implantation on augmentation cystoplasty in patients with myelodysplasia].

PURPOSE: We investigated the results of Le Duc-Camey procedure as a method of ureteroileal implantation on augmentation cystoplasty in patients with myelodysplasia. MATERIALS AND METHODS: A total of 14 patients (25 renal units) underwent ureteroileal implantation with Le Duc-Camey procedure on augmentation cystoplasty. The possible causes of complications concerning ureteroileal implantation that developed during the postoperative observation were classified as preoperative factors and postoperative factors.: The preoperative factors were the causative disease required ureteroneostomy, the grade of preoperative VUR, and the ureteral diameter at the anastomosis with the ileum.: The postoperative factors were the volume, and the compliance of the urinary bladder, and the maximum intravesical pressureled by the peristalsis of the utilized intestine. RESULTS: With the mean observation period of 31.6 months, no complications developed but VUR observed in 4 renal units of 4 patients. The patients with VUR had a larger ureteral diameter at the anastomosis site to the ileum among the preoperative factors and a significantly larger maximum intravesical pressure led by the intestinal peristalsis among the postoperative factors when compared with the patients without VUR. CONCLUSION: Regarding ureteroileal implantation with Le Duc-Camey procedure on augmentation cystoplasty in patients with myelodysplasia. It seems necessary to consider some countermeasures for the dilated ureters and for the unexpected 2 elevation of intravesical pressure due to the peristalsis of the utilized intestine.

Adolescent↗
PubMed2001

Heterogeneous expression of nonmuscle myosin heavy chain-B in mesangial cells of patients with Gitelman's syndrome.

AIMS: It has been suggested that angiotensin II (Ang II) promotes hypertrophy and hyperplasia of mesangial cells. Nonmuscle myosin heavy chain-B (NMHC-B) and alpha-smooth muscle (SM) actin are considered to be molecular markers for phenotypic change ofproliferative mesangial cells. One of the clinical characteristics in Gitelman's syndrome (GS) is the elevation of plasma Ang II. However, little is known about the relation between Ang II and phenotypic change of mesangial cells in patients with GS. In this report, we examined the expression of NMHC-B and alpha-SM actin in mesangial cells of two GS patients. MATERIALS AND METHODS: Plasma renin activity, and the concentrations of Ang II, 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), urinary kallikrein, and 6-keto-PGF1alpha were measured. Immunohistochemical staining of NMHC-B and alpha-SM actin in mesangial cells of GS patients was also performed. RESULTS: Both cases of GS showed normal glomerular function, few histological abnormalities, and higher than normal plasma concentrations of renin and Ang II. Furthermore, one case showed a high urinary concentration of kallikrein and the expression of both NMHC-B and alpha-SM actin in mesangial cells. The other case showed a high urinary concentration of 6-keto-PGF1alpha but not kallikrein and without the expression of NMHC-B and alpha-SM actin. CONCLUSION: Not only plasma kinin-kallikrein and prostaglandins, but the renal expression of NMHC-B and alpha-SM actin may be variable in different patients with GS.

Actins↗
PubMed2000

Dysfunction of M-channel enhances propagation of neuronal excitability in rat hippocampus monitored by multielectrode dish and microdialysis systems.

To explore the pathogenesis of benign familial neonatal convulsions (BFNC), we determined effects of KCNQ-related M-channels (KCNQ-channels) on hippocampal glutamate (Glu) and gamma-aminobutyric acid (GABA) releases using microdialysis, and propagation of evoked field-potentials (FP) using multielectrode (64-ch)-dish system as two-dimensional monitoring. KCNQ-channel inhibitor, Dup996, enhanced hippocampal K(+)-evoked Glu and GABA releases without affecting basal releases of them. Dup996 unaffected FP-amplitude, but enhanced FP-propagation. The GABA(A)-receptor antagonist, bicuculline, enhanced the stimulatory effects of Dup996 on FP-propagation, however, this stimulatory effects of Dup996 were abolished by the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/glutamate-receptor antagonist, DNQX. These results suggest that the occurrence of BFNC cannot be produced by KCNQ-channel dysfunction alone, but by reciprocal action between impaired KCNQ-channel and other unknown elements (possibly dysfunction of inhibitory neurotransmission system).

Action Potentials↗
PubMed2000

Refolding of target proteins from a "rigid" mutant chaperonin demonstrates a minimal mechanism of chaperonin binding and release.

One of the most interesting facets of GroEL-facilitated protein folding lies in the fact that the requirement for a successful folding reaction of a given protein target depends upon the refolding conditions used. In this report, we utilize a mutant of GroEL (GroEL T89W) whose domain movements have been drastically restricted, producing a chaperonin that is incapable of utilizing the conventional cyclic mechanism of chaperonin action. This mutant was, however, still capable of improving the refolding yield of lactate dehydrogenase in the absence of both GroES and ATP hydrolysis. A very rapid interconversion of conformations was detected in the mutant immediately after ATP binding, and this interconversion was inferred to form part of the target release mechanism in this mutant. The possibility exists that some target proteins, although dependent on GroEL for improved refolding yields, are capable of refolding successfully by utilizing only portions of the entire mechanism provided by the chaperonins.

Adenosine Triphosphate↗
PubMed2000

A compact monomeric intermediate identified by NMR in the denaturation of dimeric triose phosphate isomerase.

The denaturation of triose phosphate isomerase (TIM) from Saccharomyces cerevisiae by guanidine hydrochlorids at pH 7.2 has been monitored by NMR spectroscopy in conjunction with optical spectroscopy. In the absence of denaturant, the hydrodynamic radius of 29.6(+/-0.25) A and the substantial chemical shift dispersion evident in the NMR spectrum are consistent with the highly structured dimeric native state of the protein. On the addition of 2. 2 M guanidine hydrochloride the effective hydrodynamic radius increases to 51.4(+/-0.43) A, consistent with that anticipated for the polypeptide chain in a highly unstructured random coil state. In 1.1 M guanidine hydrochloride, however, the effective hydrodynamic radius is 24.0(+/-0.25) A, a value substantially decreased relative to that of the native dimeric state but very close to that anticipated for a monomeric species with native-like compaction (23. 5 A). The lack of chemical shift dispersion indicates, however, that few tertiary interactions persist within this species. Far UV CD and intrinsic fluorescence measurements show that this compact intermediate retains significant secondary structure and that on average the fluorophores are partially excluded from solvent. Such a species could be important in the formation of dimeric TIM from its unfolded state.

Circular Dichroism↗
PubMed2000

Stimulatory effect of curcumin on osteoclast apoptosis.

Curcumin is a potent inhibitor of the transcriptional factors activator protein-1 and nuclear factor-kappaB. Since transcriptional factors may play a functional role in the survival of osteoclasts, it was of interest to us to examine the effect of curcumin on osteoclast apoptosis. We observed that curcumin is a potent stimulator of this process in rabbit osteoclasts, as evidenced by morphological changes in nuclei and DNA fragmentation as criteria of apoptosis. The curcumin stimulation of the osteoclast apoptosis was dose-and treatment time-dependent. In addition, curcumin dramatically inhibited osteoclastic bone resorption, supporting our data that curcumin is a potent stimulator of osteoclast apoptosis.

Animals↗
PubMed2000

Effects of carbamazepine on acetylcholine release and metabolism.

To clarify the mechanisms of action of carbamazepine (CBZ), we investigated the effects of CBZ on acetylcholine (ACh) release and metabolism in rat striatum and hippocampus. Acute administration of effective dose of CBZ (25 mg/kg) increased both striatal and hippocampal extracellular levels of ACh, whereas a supraeffective dose of CBZ (50 mg/kg) did not affect the levels and a toxic dose of CBZ (100 mg/kg) decreased the extracellular ACh levels in both brain regions. Both acute and chronic administrations of CBZ (25 and 50 mg/kg, mg/kg per day) increased intracellular ACh levels in striatum and hippocampus. The striatal intracellular ACh levels were decreased by both acute and chronic administrations of CBZ (100 mg/kg, mg/kg per day), whereas the hippocampal intracellular ACh levels were not affected. The effective CBZ concentration did not affect cholinesterase activity, whereas supraeffective CBZ concentration reduced it weakly. Effective dose of CBZ enhanced ACh release and synthesis; however, supraeffective doses of CBZ reduced ACh release and synthesis without enhancement of ACh degradation, indicating that CBZ has biphasic effects on ACh release and synthesis. Thus, the present findings, the slight stimulation of ACh function by effective dose of CBZ, are involved, at least partially, in the antiepileptic and mood stabilizing mechanisms of action of CBZ.

Acetylcholine↗
PubMed2000

Dilazep, a nucleoside transporter inhibitor, modulates cell cycle progression and DNA synthesis in rat mesangial cells in vitro.

The direct effects of the nucleoside transporter inhibitor dilazep on the cell cycle of mesangial cells have not before been investigated. The purpose of this study was to elucidate whether dilazep can inhibit the proliferation of mesangial cells and how it interferes with the cell cycle of these cells. DNA histograms were used and BrdUrd uptake rate was measured by flow cytometry. There was no significant difference in the cell numbers among the untreated group and the 10(-5) M, 10(-6) M or 10(-7) M dilazep-treated groups at 24 h of incubation. However, at 48 and 72 h, the cell numbers in the dilazep-treated groups were significantly lower compared with that of the untreated group (P < 0.005). The DNA histograms of cultured rat mesangial cells at 12, 24, and 48 h of incubation with 10(-5) M dilazep showed that the ratio of the S phase population in the dilazep-treated group decreased by 2.2% at 12 h, by 9.6% at 24 h, and by 18.9% at 48 h compared with the untreated group. The ratio of the G0/G1 phase population in the dilazep-treated group significantly increased: 6.8% at 12h (P < 0.05), 13.9% at 24 h (P < 0.001), and 76.5% at 48 h (P < 0.001) compared with the untreated group. A flow cytometric measurement of bivariate DNA/BrdUrd distribution demonstrated that the DNA synthesis rate in the S phase decreased after 6 h (P < 0.005) and 12 h (P < 0.05) of incubation compared with the untreated group. These results suggest that dilazep inhibits the proliferation of cultured rat mesangial cells by suppressing the G1/S transition by prolonging G2/M and through decreasing the DNA synthesis rate.

Animals↗