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T Nakazawa

Publications and source records attributed to T Nakazawa.

At least 55 records · Page 3Linked to original sources
PubMed2001

Contribution of small GTPase Rho and its target protein rock in a murine model of lung fibrosis.

Excess fibroblasts and inflammatory cells may play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). The small GTPase, Rho, and its target protein, Rho-associated coiled-coil-forming protein kinase (ROCK), have been recognized to be major regulators of cell locomotion mediated by reorganization of the actin cytoskelton. Activated ROCK inhibits myosin phosphatase, and this in turn induces phosphorylation of the myosin light chain (MLC). To determine the mechanisms underlying the deterioration process of IPF, we investigated the effect of Y-27632, a selective ROCK inhibitor, in a murine model of bleomycin (BLM)-induced lung fibrosis. The Aschcroft score and hydroxyproline content of the BLM-treated mouse lung decreased in response to Y-27632 treatment. The number of broncoalveolar cells was decreased by Y-27632, and migration of macrophages, neutrophils, and fibroblasts in vitro was inhibited by Y-27632 regardless of various stimuli. Although expression of ROCK-II mRNA in the lung homogenates of the BLM-treated mice was increased approximately 9-fold, expression of ROCK-II protein showed only a slight tendency to increase. BLM elevated MLC phosphorylation levels, and Y-27632 inhibited BLM response. These findings indicate that the Rho/ROCK-mediated pathway plays an important role in IPF, and that blocking of this pathway leads to inhibition of IPF development.

Animals↗
PubMed2001

Nefiracetam metabolism by human liver microsomes: role of cytochrome P450 3A4 and cytochrome P450 1A2 in 5-hydroxynefiracetam formation.

An in-vitro study was conducted to investigate the metabolism of nefiracetam in human liver microsomes and to identify the enzymes responsible for the metabolism. Nefiracetam was hydroxylated by human liver microsomes to 5-hydroxynefiracetam (5-OHN). Eadie-Hofstee plots for the formation of 5-OHN suggested substrate activation. The kinetic parameters, apparent Km, Vmax, and Hill coefficient, for the formation of 5-OHN by pooled human liver microsomes were 4012 microM, 2.66 nmol min(-1) (mg protein)(-1), and 1.65, respectively. The formation of 5-OHN was significantly correlated with cytochrome P450 (CYP)3A4-mediated testosterone 6beta-hydroxylase activity and dextromethorphan N-demethylase activity. The 5-OHN formation was inhibited (94%) by antibody to human CYP3A4/5. The 5-OHN formation was also inhibited by the CYP3A4 inhibitors ketoconazole and troleandomycin, but not significantly inhibited by several other P450 inhibitors. The microsomes containing cDNA-expressed CYP3A4 formed 5-OHN with sigmoidal kinetics. CYP3A5-containing microsomes did not form 5-OHN. These results indicated that CYP3A, most likely CYP3A4, was the major isozyme responsible for the formation of 5-OHN in human liver microsomes. CYP1A2 and CYP2C19 microsomes were also capable of forming 5-OHN. However, the contribution of CYP1A2 was considered to be relatively minor compared with that of CYP3A4, and the contribution of CYP2C19 was assumed to be negligible, based on the result of the immunoinhibition study and taking into account both the turnover rate by each isozyme and the relative abundance of each isozyme in human liver. We conclude that on average the formation of 5-OHN, the major metabolite of nefiracetam, is principally mediated by CYP3A4 with a relatively minor contribution by CYP1A2.

Antibodies↗
PubMed2001

[Progress of molecular bacteriological studies on Helicobacter pylori].

To understand pathogenesis of H. pylori in stomach diseases including gastric cancer, molecular bacteriological studies are important. The studies are greatly advanced by information of the whole genome sequence of this bacterium in 1997. Various methods of gene manipulation to identify the genes involved in pathogenesis are now available such as transformation followed by construction of knockout mutants, complementation using H. pylori-E. coli shuttle vectors, random insertion mutagenesis, and RT-PCR or proteome analysis of in vivo-expressed genes. The molecular mechanism of persistent infection of H. pylori is discussed in light of recent findings on molecular mechanisms of bacterial attachment and colonization as well as on gastric physiology.

Adhesins, Bacterial↗
PubMed2001

Stimulatory effect of pseudomonal elastase on collagen degradation by cultured keratocytes.

PURPOSE: The pathobiology of corneal ulceration induced by Pseudomonas aeruginosa was investigated by characterization of the pseudomonal pathogenic factors responsible for degradation of the collagen matrix. METHODS: Three-dimensional gels of type I collagen containing (or not) rabbit keratocytes were incubated in the presence of either culture supernatant of P. aeruginosa strain PAO1 or pseudomonal pathogenic factors (elastase, lipopolysaccharide, or exotoxin A), and the extent of collagen degradation was assessed after 24 hours by measurement of released hydroxyproline. Activation of matrix metalloproteinases (MMPs) produced by keratocytes was also examined by gelatin zymography and immunoblot analysis. RESULTS: In the absence of keratocytes, the PAO1-conditioned medium increased the extent of collagen degradation. The conditioned medium also promoted keratocyte-mediated collagen degradation. Of the pseudomonal pathogenic factors examined, only elastase degraded collagen directly as well as stimulated keratocyte-mediated collagen degradation. Culture supernatant of elastase-deficient P. aeruginosa (lasR or lasB) mutants had no effect on collagen degradation in the absence or presence of keratocytes. Elastase also induced the conversion of the inactive precursors of MMP-1, -2, -3, and -9 produced by keratocytes to the active forms of the enzymes. CONCLUSIONS: These results suggest that pseudomonal elastase both degrades type I collagen directly and promotes collagen degradation mediated by keratocytes, the latter effect being likely attributable, at least in part, to the activation of proMMPS:

ADP Ribose Transferases↗
PubMed2001

[Chronotherapy of bronchial asthma: circadian rhythms in asthmatic symptoms. Report I: Survey on chronobiology acrophase of asthmatic symptoms].

We conducted a questionnaire survey on the onset time and frequency of asthmatic symptoms in adults with bronchial asthma who were regular clinic attendees in 17 sites in Chiba Prefecture, and analyzed 513 respondents. As a result, the frequency of wheezing was 54.6%, the highest of all symptoms. Feeling of chest discomfort was 32.2%, followed by asthma attack (13.8%), cough (8.7%) and dynpnea (6.8%). Asthmatic symptoms were highest from midnight to early morning, with the peak at around 4 o'clock am. The same pattern was seen regardless of the severity and types of asthma. This survey also showed that conventional anti-asthmatic therapies decreased the frequency of nightly asthmatic symptoms from the baseline: 7 times or more per week reduced from 44.9% to 16.1%, 3 times or more per week from 76.8% to 40.4%, and at least once per week from 94.4% to 71.5%. The results suggest that it is important to take another therapeutic strategy, which can administer medications at the appropriate time according to the circadian rhythms in asthmatic patients to better control asthma.

Adult↗
PubMed2001

[Chronotherapy of bronchial asthma: circadian rhythms in peak expiratory flow. The report II: Circadian rhythms of peak expiratory flow in asthmatic patients and effect of sustained-release theophylline on various types of the circadian rhythms].

We monitored peak expiratory flow (PEF) in outpatients with adult bronchial asthma in 17 sites in Chiba prefecture 4 times daily for 2 weeks, using a peak flow meter to categorize the patients by circadian patterns of PEF. Then a sustained-release theophylline preparation formulated for once-daily dosing was administered to these patients grouped to examine the effect of the drug on circadian rhythms in PEF. Analysis was performed in 215 of total 245 patients enrolled as a result of excluding 30 ineligible patients. 187 patients (87.0%) exhibited a certain rhythm in their PEF, and 28 patients (13.0%) did not show any particular rhythm. These 187 patients with a certain rhythm in PEF were grouped into 63 patients (29.3%) of morning-dip type, 83 patients (38.6%) of peak type, 7 patients (3.3%) of evening-dip type, and 34 patients (15.8%) of flat type. And there were no trough-type patients. Uniphyl tablets were administered once a day at a daily dosage of 400 mg after supper to 124 patients of the above 187 patients grouped according to circadian patterns of PEF. Uniphyl was particularly effective in the morning-dip type and the peak type. This result suggests that it is necessary to take circadian rhythms of PEF into consideration in drug therapy for patients with bronchial asthma.

Adolescent↗
PubMed2001

[Bronchial asthma among adults].

Approximately 5800-6200 adult asthma patients have died yearly in 1980-1992. This number has tended to decrease over the years except 1995. In recent 3 years; 1997, 1998 and 1999, it decreased to 5589, 5065 and 5360, respectively. Males were slightly more than females among the death cases. Two-thirds of the patients were 70-80 year old. Death of young male adults in twenties notably increased in past 10 years but it decreased in recent 3 years. One third of the patients showed sudden death type occurring within 1-3 hours after onset of asthma attack. The majority of asthma attacks leading to death actually start while the patient is at home. More than half of the patients were classified into intrinsic or mixed type of asthma and also graded as severe-type asthma. The main causes of the fatal asthma attacks were respiratory infections, fatigue and stress. Fifty-two percent of them were smokers including ex-smokers. Pulmonary emphysema showed relatively high frequency as a complication.

Adult↗
PubMed2001

[Thrombosis of the abdominal aorta in a patient with nephrotic syndrome].

Nephrotic syndrome frequently causes thromboembolic complications in veins. Arterial thrombosis, however, is relatively rare. We report the case of a 47-year-old male with nephrotic syndrome complicated with abdominal aortic thrombosis. The patient complained of pain in the bilateral lower extremities 2 weeks after the development of nephrotic syndrome. The aortogram revealed complete occlusion of the abdominal aorta just below the origin of the inferior mesenteric artery. Necrosis of the legs extended rapidly, and he eventually lost his legs. Among various predisposing factors, hypercoagulability associated with nephrotic syndrome seemed to be responsible for the development of thrombosis. Thrombotic complications are sometimes serious in the nephrotic patient. Assessment for the risk factors is required to warrant prophylactic anticoagulation.

Amputation, Surgical↗
PubMed2000

Evaluation of Y-27632, a rho-kinase inhibitor, as a bronchodilator in guinea pigs.

To evaluate (+)-(R)-trans-4-(l-Aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride, monohydrate (Y-27632), a selective Rho-kinase inhibitor, as a novel bronchodilator in vivo and in vitro, we investigated the effect of Y-27632 on the acetylcholine- or ovalbumin-induced increase in lung resistance (R(L)) in non-sensitized or passively sensitized guinea pigs, and the relaxant effects of salbutamol, Y-27632 and theophylline on acetylcholine- or ovalbumin-induced contraction of isolated trachea. Y-27632 inhalation (1 mM, 2 min) inhibited acetylcholine- or ovalbumin-induced increase in R(L) without changes in mean blood pressure, and the effect persisted for at least 3 h. Salbutamol, Y-27632 and theophylline each completely reversed the acetylcholine- or ovalbumin-induced contraction of isolated trachea with rank order of potency, salbutamol>Y-27632>theophylline. The relaxant effect of Y-27632 was not affected by propranolol. We conclude that, although Y-27632 is not as potent as a beta-adrenoceptor agonist, Y-27632 may become an alternative inhaled bronchodilator, because Y-27632 is more potent than theophylline, and the relaxant effect is independent of beta-adrenoceptors.

Acetylcholine↗
PubMed2000

Identification of the differential distribution patterns of mRNAs and consensus binding sequences for mouse DAF-16 homologues.

daf-16 is a forkhead-type transcription factor, functioning downstream of insulin-like signals, and is known to be critical to the regulation of life span in Caenorhabditis elegans. Mammalian DAF-16 homologues include AFX, FKHR and FKHRL1, which contain a conserved forkhead domain and three putative phosphorylation sites for the Ser/Thr kinase Akt/protein kinase B (PKB), as well as for DAF-16. To assess the function of the homologues, we examined tissue distribution patterns of mRNAs for DAF-16 homologues in mice. In the embryos, expressions of AFX, FKHR and FKHRL1 mRNAs were complementary to each other and were highest in muscle, adipose tissue and embryonic liver. The characteristic expression pattern remained in the adult, except that signals of FKHRL1 became evident in more tissues, including the brain. In order to clarify whether each DAF-16 homologue had different target genes, we determined the consensus sequences for the binding of DAF-16 and the mouse homologues. The binding sequences for all four proteins shared a core sequence, TTGTTTAC, daf-16 family protein-binding element (DBE) binding protein. However, electrophoretic mobility shift assay showed that the binding affinity of DAF-16 homologues to the core sequence was stronger than that to the insulin-responsive element in the insulin-like growth factor binding protein-1 promoter region, which has been identified as a binding sequence for them. We identified one copy of the DBE upstream of the first exon of sod-3 by searching the genomic database of C. elegans. Taken together, DAF-16 homologues can fundamentally regulate the common target genes in insulin-responsive tissues and the specificity to target genes of each protein is partially determined by the differences in their expression patterns.

Alternative Splicing↗
PubMed2000

Comparison of whole genome sequences of Chlamydia pneumoniae J138 from Japan and CWL029 from USA.

Chlamydia pneumoniae is a widespread pathogen of humans causing pneumonia and bronchitis. There are many reports of an association between C.PNEUMONIAE: infection and atherosclerosis. We determined the whole genome sequence of C.PNEUMONIAE: strain J138 isolated in Japan in 1994 and compared it with the sequence of strain CWL029 isolated in the USA before 1987. The J138 circular chromosome consists of 1 226 565 nt (40.7% G+C) with 1072 likely protein-coding genes that is 3665 nt shorter than the CWL029 genome. Plasmids, phage- or transposon-like sequences were not identified. The overall genomic organization, gene order and predicted proteomes of the two strains are very similar, suggesting a high level of structural and functional conservation between the two unrelated isolates. The most conspicuous differences in the J138 genome relative to the CWL029 genome are the absence of five DNA segments, ranging in size from 89 to 1649 nt, and the presence of three DNA segments, ranging from 27 to 84 nt. The complex organization of these 'different zones' may be attributable to a unique system of recombination.

Base Composition↗
PubMed2000

The SCG10-related gene family in the developing rat retina: persistent expression of SCLIP and stathmin in mature ganglion cell layer.

Neuronal growth-associated proteins (GAPs), such as GAP-43 and SCG10, are thought to play crucial roles in both axonal and dendritic outgrowth during neural development and regeneration, although the underlying mechanisms remain largely unknown. The recent finding that SCG10 is a microtubule regulator and also the identification of RB3 and SCLIP as two new SCG10-related members prompted us to investigate the roles of SCG10-related family in neural development, using the retina as a model system. We determined the temporal expression and the spatial distribution of SCG10-related mRNAs in the developing rat retina. Semiquantitative analysis by RT-PCR revealed that in prenatal retina, levels of SCG10 and stathmin mRNAs were higher than those of RB3 and SCLIP. In the postnatal retina, the level of SCLIP increased, whereas the level of RB3 remained low. In situ hybridization revealed that GAP-43 and all of the SCG10-related family mRNAs were present in the retinal ganglion cells (RGCs) at all stages of retinal development, and that stathmin mRNA was present in mitotic neuroblastic cells. Differential expression of SCG10 and other members of the family became more evident as retinal development proceeded; SCG10 and RB3 expression were relatively specific in the RGCs and amacrine cells, whereas SCLIP was also evident in bipolar and horizontal cells. Stathmin mRNA was highly expressed both in the RGCs and other interneurons. These results indicate that multiple SCG10-related proteins are expressed in single neurons including RGCs, and suggest that these nGAPs play similar but distinct roles in differentiation and functional maintenance of retinal neurons.

Animals↗
PubMed2000

Effect of calyculin A on the surface structure of unfertilized sea urchin eggs.

Calyculin A, a potent inhibitor of type 1 and type 2A protein phosphatases, induces contractile ring formation when applied to unfertilized sea urchin eggs [Tosuji et al., 1992: Proc. Natl. Acad. Sci. USA 89:10613-10617]. We report here the elongation of microvilli in the unfertilized eggs exposed to calyculin A. The elongated microvilli and associated sperm-egg binding sites (egg receptor for sperm) then became concentrated into a constriction site corresponding to the cleavage furrow. The egg receptor for sperm was also in close connection to the microfilaments. Okadaic acid is another known inhibitor of protein phosphatase type-1 and type-2A. Its effect, however, is about a hundredfold feebler for type-1 phosphatase than type-2A. Even after treatment with okadaic acid, no change was observed, suggesting that these morphological changes were induced by calyculin A solely though its inhibitory effect on the type-1 protein phosphatase.

Acrosome Reaction↗
PubMed2000

Theophylline induces neutrophil apoptosis through adenosine A2A receptor antagonism.

This study was designed to determine whether theophylline would augment granulocyte apoptosis via a mechanism of adenosine A2A receptor antagonism. A selective adenosine A2 receptor agonist (CGS-21680, 1 microM) exhibited the most efficient potency for decreasing neutrophil apoptosis for 16 h from 63+/-5 to 19+/-4% (P < 0.001); it exerted poor and adverse effects on eosinophil survival. A selective protein kinase A inhibitor KT-5720 (10 microM) reversed the capacity of dibutyryl cAMP but not CGS-21680 to induce an inhibitory effect on neutrophil apoptosis, suggesting that occupancy of adenosine A2 receptors inhibit neutrophil apoptosis by a cAMP-independent mechanism. Theophylline derivatives show the following pattern of potency for inducing neutrophil apoptosis competing with CGS-21680: 8-phenyltheophylline = 8-p-sulfophenyltheophylline > theophylline >> enprofylline. This pattern is consistent with the affinity established for A2A receptors. Theophylline demonstrated an additive effect to that of anti-Fas antibody (CH11, 1 microg/mL) in inducing neutrophil apoptosis, but not to that of adenosine deaminase or KF-17837 (a selective A2 receptor antagonist; 1 microM), suggesting conflicting effects on the receptor antagonism. These findings suggest that theophylline has an immunomodulatory action on neutrophil apoptosis via a mechanism of A2A antagonism.

Adenosine↗
PubMed2000

Adjuvant-induced improvement of glucose intolerance in type 2 diabetic KK-Ay mice through interleukin-1 and tumor necrosis factor-alpha.

We reported that administration of complete Freund's adjuvant (CFA) improved glucose tolerance test (GTT) results in obese diabetic KK-Ay mice. In this study, we investigated its mechanism. An injection with CFA remarkably improved GTT for more than a week in KK-Ay mice, although insulin response was not changed compared with saline controls. The hypoglycemic effect of insulin was significantly, but partially, potentiated in the CFA-treated mice compared with the controls, suggesting that CFA stimulated insulin-mediated and non-insulin-mediated glucose disposal. Improvement in the GTT with CFA was partially transferable to nontreated mice by peritoneal exudative cells, but not spleen or lymph node cells. Pretreatment with anti-interleukin (IL)-1 alpha and -1 beta antibodies or anti-tumor necrosis factor (TNF)-alpha antibody significantly abrogated the improvement in the GTT with CFA. The results indicate that CFA-induced improvement in glucose intolerance in KK-Ay mice was mediated at least by IL-1 and TNF-alpha.

Animals↗
PubMed2000

Tissue-specific actions of antidiabetic thiazolidinediones on the reduced fatty acid oxidation in skeletal muscle and liver of Zucker diabetic fatty rats.

Fatty acid overload has been proposed as a cause of decreased responsiveness in the major insulin target tissues of the body such as muscle and liver tissue. We therefore investigated fatty acid oxidation in soleus muscle and liver isolated from Zucker diabetic fatty (ZDF) rats treated with thiazolidinediones, a new class of antidiabetic agents. 14CO2 production from [14C]palmitic (C16:0) acid was lower in the soleus muscle and liver of ZDF rats versus lean rats (P < .05). When administered orally to ZDF rats for 2 weeks, the thiazolidinediones troglitazone (300 mg/kg) and KRP-297 (10 mg/kg) increased palmitic acid oxidation in the soleus muscle of ZDF rats (P < .05). KRP-297, but not troglitazone, increased palmitic acid oxidation in the liver of ZDF rats (P < .05), and both troglitazone and KRP-297 inhibited triglyceride accumulation in the skeletal muscle of ZDF rats. Hepatic triglyceride accumulation in ZDF rats was inhibited by KRP-297, but not by troglitazone. A reduction of fatty acid oxidation in the liver of ZDF rats and an increase in response to KRP-297 were observed only when C16:0 and C18:0 fatty acids, not C8:0, were used as substrates. Thus, there were defects in fatty acid catabolic activity and triglyceride accumulation in the soleus muscle and liver of ZDF rats. These results indicate that KRP-297 has advantages over troglitazone in the amelioration of these lipid metabolic abnormalities in insulin resistance associated with obesity.

Administration, Oral↗