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Y Yoshida

Publications and source records attributed to Y Yoshida.

At least 181 records · Page 10Linked to original sources
PubMed2000

Genetic analysis of the gene cluster for the synthesis of serotype a-specific polysaccharide antigen in Aactinobacillus actinomycetemcomitans.

The serotype a-specific polysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans consists of 6-deoxy-D-talose. A gene cluster associated with the biosynthesis of SPA was cloned and sequenced from the chromosomal DNA of A. actinomycetemcomitans SUNYaB 75 (serotype a). This cluster consisted of 14 open reading frames. Insertional inactivation of eight genes in this cluster resulted in loss of the ability of A. actinomycetemcomitans SUNYaB 75 cells to produce the polysaccharide. A protein database search revealed that the 11 sequential genes containing these eight genes were not found in SPA-associated gene clusters of the other serotypes of A. actinomycetemcomitans. These results suggest that the gene cluster is unique to serotype a and is essential to the synthesis of the SPA.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Ganglioside GD3 and its mimetics induce cytochrome c release from mitochondria.

Ganglioside GD3 induced the release of cytochrome c from isolated rat liver mitochondria. This process was completely prevented by cyclosporin A and partially prevented by a cysteine protease inhibitor, n-acetyl-leu-leu-norleucinal. Cyclosporin A is a potent inhibitor of the permeability transition pore, whereas n-acetyl-leu-leu-norleucinal has no effect on this pore. These results indicate that the release of cytochrome c from mitochondria requires both the opening of the permeability transition pore and a cysteine protease inhibitor-sensitive mechanism. Gangliosides GD1a, GD1b, GT1b, and GQ1b along with the synthetic GD3 mimetics TMS-42 and CI-22, which are glycerophospholipids carrying a disialo residue, also induced cytochrome c release. In contrast, gangliosides GM1, GM2, and GM3 did not induce cytochrome c release. These results indicate that two sialo residues must play an important role in the induction of cytochrome c release by gangliosides.

Animals↗
PubMed2000

Oral administration of tetrahydrobiopterin prevents endothelial dysfunction and vascular oxidative stress in the aortas of insulin-resistant rats.

We have reported that a deficiency of tetrahydrobiopterin (BH(4)), an active cofactor of endothelial NO synthase (eNOS), contributes to the endothelial dysfunction through reduced eNOS activity and increased superoxide anion (O(2)(-)) generation in the insulin-resistant state. To further confirm this hypothesis, we investigated the effects of dietary treatment with BH(4) on endothelium-dependent arterial relaxation and vascular oxidative stress in the aortas of insulin-resistant rats. Oral supplementation of BH(4) (10 mg. kg(-1). d(-1)) for 8 weeks significantly increased the BH(4) content in cardiovascular tissues of rats fed high levels of fructose (fructose-fed rats). Impairment of endothelium-dependent arterial relaxation in the aortic strips of the fructose-fed rats was reversed with BH(4) treatment. The BH(4) treatment was associated with a 2-fold increase in eNOS activity as well as a 70% reduction in endothelial O(2)(-) production compared with those in fructose-fed rats. The BH(4) treatment also partially improved the insulin sensitivity and blood pressure, as well as the serum triglyceride concentration, in the fructose-fed rats. Moreover, BH(4) treatment of the fructose-fed rats markedly reduced the lipid peroxide content of both aortic and cardiac tissues and inhibited the activation of 2 redox-sensitive transcription factors, nuclear factor-kappaB and activating protein-1, which were increased in fructose-fed rats. The BH(4) treatment of control rats did not have any significant effects on these parameters. These results indicate that BH(4) augmentation is essential for the restoration of eNOS function and the reduction of vascular oxidative stress in insulin-resistant rats.

Administration, Oral↗
PubMed2000

Immunohistochemical expression of Bcl-2, Bax and cytochrome c following focal cerebral ischemia and effect of hypothermia in rat.

Recent studies suggest that mild hypothermia significantly alleviate damage following cerebral ischemia though the precise mechanism is poorly defined. In the present study, middle cerebral artery occlusion (MCAo) was induced in Sprague-Dawley (SD) rats for 1 h followed by varying periods of reperfusion. Cerebral infarcts identified by hematoxylin & eosin (H&E) staining revealed extensive lesion in normothermic (NT) 37 degrees C and small lesion in hypothermic (HT) 33 degrees C group of rats. Immunohistochemical analysis revealed Bcl-2 was induced in many neurons of HT group, while Bax and cytochrome c was induced in few neurons. In situ detection of DNA fragmentation using 3'-OH end labeling method (terminal dUTP nick-end labelling (TUNEL)) indicated, higher number of TUNEL-positive cells in NT group, but significantly decreased in HT group. The expression pattern revealed many neurons at the penumbra region could survive in HT group whereas, many neurons are committed to die in NT group. Our results suggest that hypothermia is selectively interfering at more than one place and providing protection.

Animals↗
PubMed2000

Autocrine action and its underlying mechanism of nitric oxide on intracellular Ca2+ homeostasis in vascular endothelial cells.

The rise in cytosolic Ca(2+) concentration (Ca(2+)(i)) in vascular endothelial cells (ECs) activates the production and release of nitric oxide (NO). NO modifies Ca(2+)(i) homeostasis in many types of nonendothelial cells. However, its effect on endothelial Ca(2+)(i) homeostasis at basal and excited states remains unclear. In the present study, to elucidate the effect of NO on basal Ca(2+)(i), inositol 1,4,5-trisphosphate-induced Ca(2+)(i) release (IICR) was blocked by expressing an antisense against type-1 inositol 1,4,5-trisphosphate receptors or by microinjecting heparin to individual ECs, and the effects of NO that was released by and diffused from adjacent IICR-intact ECs were recorded. After ATP or bradykinin stimulation, IICR-inhibited ECs showed a marked reduction of basal Ca(2+)(i), which was abolished by N(G)-monomethyl-l-arginine monoacetate pretreatment. The reduction disappeared in sparsely seeded ECs. Exogenous NO gas mimicked the effect of ATP or bradykinin to reduce basal Ca(2+)(i). Blocking plasma membrane Ca(2+)-ATPase (PMCA), but not Na(+)-Ca(2+) exchange or sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase, suppressed the reduction, indicating that the reduction resulted from a NO-dependent potentiation of PMCA. To elucidate the effect of NO on elevated Ca(2+)(i), ATP-, bradykinin-, or thapsigargin-evoked Ca(2+)(i) response in the presence and absence of NO production was compared in adjacent IICR-intact ECs. NO was found to potentiate PMCA, which, in turn, greatly attenuated agonist-evoked Ca(2+)(i) elevation. NO also potentiated Ca(2+) influx, which markedly increased the sustained phase of Ca(2+)(i) elevation and possibly NO production. NO did not affect other Ca(2+)(i)-elevating and Ca(2+)(i)-sequestrating components. Thus, NO-dependent potentiation of PMCA is crucial for Ca(2+)(i) homeostasis over a wide Ca(2+)(i) range.

Adenosine Triphosphate↗
PubMed2000

A gene cluster for the synthesis of serotype d-specific polysaccharide antigen in Actinobacillus actinomycetemcomitans.

The serotype d antigen of Actinobacillus actinomycetemcomitans consists of D-glucose, D-mannose, and L-rhamnose in a molar ratio of 1:2:1. A gene cluster involved in the synthesis of serotype-specific polysaccharide antigen was cloned from the chromosomal DNA of A. actinomycetemcomitans IDH 781 (serotype d). This cluster consisted of 12 open reading frames. Insertional inactivation of six genes in this cluster resulted in loss of ability of A. actinomycetemcomitans IDH 781 cells to produce the polysaccharide. Comparing the structure of the gene cluster with similar clusters from other serotypes of A. actinomycetemcomitans, showed that eight genes are unique to serotype d; the other four genes are involved in the biosynthesis of dTDP-L-rhamnose. These results suggest that the synthesis and structure of serotype d-specific polysaccharide of A. actinomycetemcomitans is quite different from those of other serotype strains.

Actinobacillus↗
PubMed2000

Concentration of nonylphenol and its polyethoxylated derivatives by polymer-mediated extraction.

Polymer-mediated extraction based on thermoresponsive precipitation of poly(N-isopropylacrylamide) [PNIPAAm] was applied to the concentration of amphiphilic compounds, nonylphenyl polyethoxylates (NPnEOs), in water. Among these nonionic surfactants, NPnEOs possessing the number, n, of ethoxy unit less than 5 were quantitatively recovered in polymer precipitates when a 0.100-g portion of PNIPAAm was used for a 10 ml sample solution. Torelance limit (30 ppm) against a typical industrial anionic surfactant, sodium dodecylsulfate, strongly suggests the potential to use the present method for practical purposes. After preconcentration, trace nonylphenol and mono-ethoxylated nonylphenol (ppb-level) in a river water sample were successfully determined by high-performance liquid chromatography with ultra-violet photometric detection.

Anions↗
PubMed2000

Pyk2 and Syk participate in functional activation of granulocytic HL-60 cells in a different manner.

The roles of the protein tyrosine kinases Pyk2 (also called RAFTK or CAK beta) and Syk in the process of functional activation of human myeloid cells were examined. During granulocytic differentiation of HL-60 cells with dimethyl sulfoxide (DMSO), the amounts of Pyk2 and beta2 integrin increased, whereas the amount of Syk was abundant before differentiation and did not change during differentiation. When the granulocytic cells were stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), tyrosine phosphorylation of Pyk2 occurred promptly and subsequent association of Pyk2 with beta2 integrin was detected. In contrast, Syk was not tyrosine phosphorylated by fMLP stimulation but constitutively associated with beta2 integrin. Stimulation with fMLP also caused the alteration of beta2 integrin to an activated form, a finding that was confirmed by the observation of fMLP-induced cell attachment on fibrinogen-coated dishes and inhibition of this attachment by pretreatment with anti-beta2 integrin antibody. Cell attachment to fibrinogen caused the enhanced tyrosine phosphorylation of Pyk2 and the initial tyrosine phosphorylation of Syk, which was also inhibited by pretreatment with anti-beta2 integrin antibody. In vitro kinase assays revealed that Pyk2 and Syk represented kinase activities to induce tyrosine phosphorylation of several molecules in the anti-beta2 integrin immunoprecipitates of the attached cells. These results showed that Pyk2 is involved in the functional activation of granulocytic cells in 2 signaling pathways: an fMLP receptor-mediated "inside-out" signaling pathway that might cause beta2 integrin activation and a subsequent beta2 integrin-mediated "outside-in" signaling pathway. Syk was activated in relation to cell attachment to fibrinogen as a result of "outside-in" signaling, although it was already associated with beta2 integrin before fMLP stimulation. (Blood. 2000;96:1733-1739)

CD18 Antigens↗
PubMed2000

Cloning and characterization of the mouse tob2 gene.

Human Tob2 is a member of the Tob/BTG1 anti-proliferative family of proteins. Here, we report the molecular cloning and characterization of the mouse tob2 gene. The tob2 gene contains an open reading frame of 345 amino acids with an 89% identity to its human counterparts. The coding region of mouse tob2 is not interrupted by introns. The tob2 transcript is 4.2kb long, the size being similar to that of the human tob2 transcript, and detected ubiquitously in various tissues of adult mice. In addition, in situ hybridization shows that tob2 is ubiquitously expressed in embryo, the level of expression being especially high in skeletal muscle. Collectively, Tob2 is suggested to play roles both during embryogenesis and in adults.

3T3 Cells↗
PubMed2000

Sterol 14-demethylase P450 (CYP51) provides a breakthrough for the discussion on the evolution of cytochrome P450 gene superfamily.

Biodiversity is the most characteristic feature of cytochrome P450. Finding of CYP51 distributing widely in biological kingdoms provided breakthroughs for the discussion on the evolution and diversification of P450. Molecular phylogenetic analysis demonstrated that CYP51 appeared in the prokaryotic era and distributed into most kingdoms concomitant with phylogenetic divergence. This is the first evolutionary evidence indicating the prokaryotic origin of P450. Modification of substrate specificity of eukaryotic CYP51s occurred independently to adapt to the different sterol precursors existing in each kingdom. Formation of CYP51 variants through the mutation of active site and the selection of the advantageous ones from them were demonstrated by the emergence of azole-resistant CYP51s in Candida albicans under the environments rich in azole antifungal agents. These findings illustrate the most probable core process of P450 diversification consisting of modification of active site and selection of the resulting variants through interaction with endogenous and exogenous chemicals.

Amino Acid Sequence↗
PubMed2000

Prostaglandin E (EP) receptor subtypes and sleep: promotion by EP4 and inhibition by EP1/EP2.

Prostaglandin (PG) E2 reportedly augmented wakefulness when continuously infused into the third ventricle of the rat brain, whereas it promoted sleep when continuously infused into the subarachnoid space of the ventral surface zone of the rostral basal forebrain, which was designated previously as a PGD2-sensitive sleep-promoting zone (PGD2-SZ). In the present study, we investigated the effects of PGE (EP)-receptor agonists on sleep-wakefulness activities by infusing agonists into the third ventricle or into the subarachnoid space of the PGD2-SZ. Our results indicated that the waking effect is mediated by EP1 and EP2 receptors situating around the third ventricle, whereas the sleep-promoting effect is brought about mainly through activation of EP4 receptors located at or near the subarachnoid space of the PGD2-SZ.

Animals↗
PubMed2000

Adenovirus-mediated transfer of caspase-8 in combination with superrepressor of NF-kappaB drastically induced apoptosis in gliomas.

Inhibition of NF-kappaB in the presence of tumor necrosis factor-alpha (TNF) is supposed to be a promising cancer therapeutic approach, since it disrupts the protective mechanism of NF-kappaB activated by TNF. To test this approach in gliomas, we introduced a superrepressor of NF-kappaB, an N-terminal deleted form of inhibitor kappa B alpha (IkappaBdN) gene, to human glioma cells (U251 and U-373MG) via adenoviral vector (Adv) in the presence of TNF. U-373MG cells were refractory to TNF-induced apoptosis even when they were transduced with the IkappaBdN gene. On the other hand, transduction of IkappaBdN drastically augmented caspase-8-mediated apoptosis in U-373MG cells. Similar results were obtained in U251 cells. Cotransduction of IkappaBdN and caspase-8 induced cleavage of PARP. Taken together, Adv-mediated transfer of IkappaBdN plus caspase-8 may be a promising therapeutic approach to treat gliomas.

Adenoviridae↗
PubMed2000

Adenovirus-mediated transfer of caspase-3 with Fas ligand induces drastic apoptosis in U-373MG glioma cells.

Impaired function of apoptosis-related genes is deeply involved in oncogenesis and the progression of cancers, and caspase-3 plays a critical role as an executioner of apoptosis. We introduced the caspase-3 gene via an adenovirus (Adv) vector into Alexander hepatoma cells, MCF-7 breast cancer cells, and U251 and U-373MG glioma cells which have different endogenous levels of caspase-3 expression. None of the cell lines underwent apoptosis by overexpression of caspase-3, indicating that induction of caspase-3 alone is not applicable for cancer gene therapy. Next, we investigated whether overexpression of caspase-3 could enhance Fas ligand-mediated apoptosis in these four cell lines. In U-373MG cells, which showed the highest level of expression of surface Fas among the four cell lines, coinfection of the Adv for caspase-3 (Adv-caspase-3) and the Adv for Fas ligand (Adv-FL) induced a remarkably increased degree of apoptosis compared with that induced by the single infection of either Adv-caspase-3 or Adv-FL. Similar results were obtained by cotreatment with anti-Fas antibody in U-373MG cells. These data suggest that when strong proapoptotic upstream stimuli are induced, the level of caspase-3 expression determines the degree of apoptosis in cancer cell lines. In conclusion, overexpression of caspase-3 alone did not induce apoptosis in cancer cells. Both a strong proapoptotic signal and a high expression of caspase-3 were required to induce drastic apoptosis in cancers. This strategy would be highly beneficial for selected cancer patients.

Adenoviridae↗
PubMed2000

Thymidine diphosphate-6-deoxy-L-lyxo-4-hexulose reductase synthesizing dTDP-6-deoxy-L-talose from Actinobacillus actinomycetemcomitans.

The serotype c-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans NCTC 9710 contains an unusual sugar, 6-deoxy-L-talose, which has been identified as a constituent of cell wall components in some bacteria. Two genes coding for thymidine diphosphate (dTDP)-6-deoxy-L-lyxo-4-hexulose reductases were identified in the gene cluster required for biosynthesis of serotype c-specific polysaccharide. Both dTDP-6-deoxy-L-lyxo-4-hexulose reductases were overproduced and purified from Escherichia coli transformed with the plasmids containing these genes. The sugar nucleotides converted by both reductases were purified by reversed-phase high performance liquid chromatography and identified by (1)H nuclear magnetic resonance and gas-liquid chromatography. The results indicated that one of two reductases produced dTDP-6-deoxy-L-talose and the other produced dTDP-L-rhamnose (dTDP-6-deoxy-L-mannose). The amino acid sequence of the dTDP-6-deoxy-L-lyxo-4-hexulose reductase forming dTDP-6-deoxy-L-talose shared only weak homology with that forming dTDP-L-rhamnose, despite the fact that these two enzymes catalyze the reduction of the same substrate and the products are determined by the stereospecificity of the reductase activity. Neither the gene for dTDP-6-deoxy-L-talose biosynthesis nor its corresponding protein product has been found in other bacteria; this biosynthetic pathway is identified here for the first time.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Sensory innervation of the pharynx and larynx.

To shed light on supraesophageal complications of reflux disease, sensory innervation--particularly, distinct distribution, area, and density of sensory fibers--of the feline pharyngolaryngeal mucosa was reported. The investigations were performed by means of histochemistry (tracer techniques) and immunohistochemistry. The pharyngeal mucosa from the Eustachian cushion to the middle level of aryepiglottic fold, except the laryngeal surface of epiglottis, was supplied by the glossopharyngeal sensory fibers, whereas the laryngeal sensory fibers innervated between the apex of epiglottis and the level of the first tracheal ring in the larynx and between the middle level of aryepiglottic fold and the caudal end of piriform sinus in the pharynx. Most areas of the mucosa, except the subglottis, had unilateral innervation. The subglottis, including the caudal aspect of vocal fold and the posterior glottis, had bilateral supply with ipsilateral predominance. The density of sensory fibers in the vestibule of larynx involving the posterolateral aspect of arytenoid eminence was much heavier than the other parts. Sensory nerve fibers around the caudal pole of palatine tonsil, and in the root of tongue and the hypopharyngeal wall also were dense. Regional distribution and density of substance P and calcitonin gene-related peptide immunoreactive fibers showed almost the same pattern as did the sensory fibers.

Animals↗
PubMed2000

Sensitivity difference to the suppressive effect of prostaglandin E2 among mouse strains: a possible mechanism to polarize Th2 type response in BALB/c mice.

PGE2 has been shown to play a prominent role in regulating Th1 and Th2 type responses. We studied the role of PGE2 in IFN-gamma production by Staphylococcus aureus Cowan I-stimulated spleen cells from several mouse strains such as BALB/c, C3H/HeN, and C57BL/6. When spleen cells were pretreated with indomethacin (cyclooxygenase (COX)-1 and COX-2 inhibitor) or NS-398 (COX-2-specific inhibitor), S. aureus Cowan I -induced IFN-gamma production was increased more markedly in spleen cells from BALB/c mice than from C3H/HeN and C57BL/6 mouse. However, PGE2 production was not significantly different among spleen cells from three mouse strains. When various concentrations of PGE2 were exogeneously added to spleen cells, PGE2 showed a stronger suppressive effect on IFN-gamma production in spleen cells from BALB/c mice than from other strains of mice. This suppressive effect of PGE2 in BALB/c mice mainly depended on IL-12p70 production by APCs. More PGE2 binding sites were found in BALB/c spleen cells than in C3H/HeN spleen cells, indicating that the sensitivity difference to the suppressive effect of PGE2 was due to the difference of the number of PGE2 receptors. The administration of NS-398 into BALB/c mice enhanced Ag-specific IFN-gamma production, but not IL-4 production. This effect is the same as IL-12 administration in vivo. From these results, we propose that the modulation of PGE2 is important for Th1 activation via IFN-gamma and IL-12p70 production in vitro and in vivo and that PGE2 is one of the pivotal factors in the Th2-dominant immune response in BALB/c mice.

Adjuvants, Immunologic↗
PubMed2000

Antiarrhythmic efficacy of dipyridamole in treatment of reperfusion arrhythmias : evidence for cAMP-mediated triggered activity as a mechanism responsible for reperfusion arrhythmias.

BACKGROUND: Intracellular calcium overload is believed to play an important role in development of reperfusion arrhythmias. Dipyridamole, an inhibitor of cellular uptake of adenosine, may prevent or terminate reperfusion arrhythmias by reducing intracellular calcium overload. METHODS AND RESULTS: First, we tested for a preventive effect of dipyridamole. Sixty-one patients who underwent primary PTCA for treatment of acute anterior wall myocardial infarction were enrolled in this prospective study. Patients were divided into dipyridamole (DP) and nondipyridamole (non-DP) groups. The 2 groups had similar baseline characteristics. In the DP group, dipyridamole 0.5 mg/kg was infused intravenously for 3 minutes immediately before reperfusion during primary PTCA. Arrhythmias after reperfusion were analyzed from continuous ECG recordings. None of the patients in the DP group (n=23) had accelerated idioventricular rhythms (AIVR) or ventricular tachycardia (VT). In contrast, 7 (18.4%) had AIVR and 3 (7.9%) had VT in the non-DP group (n=38; P<0.01). Second, we tested for a termination effect of dipyridamole. Dipyridamole 0.5 mg/kg was infused intravenously while continuous ECG recordings were obtained in 9 patients who had either sustained AIVR (n=7) or sustained VT (n=2) after reperfusion of occluded coronary artery. Arrhythmias were terminated in all patients. CONCLUSIONS: These results indicate that administration of dipyridamole can prevent and terminate reperfusion arrhythmias such as AIVR and VT. cAMP-mediated triggered activity may, at least in part, be responsible for reperfusion-induced AIVR and VT.

Adenosine↗