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S Arima

Publications and source records attributed to S Arima.

At least 19 recordsLinked to original sources
PubMed2001

Feeding characteristics of two tintinnid ciliate species on phytoplankton including harmful species: effects of prey size on ingestion rates and selectivity.

The feeding abilities of two tintinnid ciliates, Favella ehrenbergii and Favella taraikaensis, on 10 species of flagellates including harmful marine algae were examined under single prey conditions, and selective feeding of F. taraikaensis on two species of algae of different sizes was investigated under mixed prey conditions. Ingestion rates calculated from the rate of increases of auto-fluorescent particles inside food vacuoles in individuals ranged from 0.5 to 22.1 cells ind(-1) h(-1) for F. ehrenbergii and from 0.8 to 44.9 cells ind(-1) h(-1) for F. taraikaensis on nine species of prey algae. Significant ingestion rates of both Favella species could not be detected on Heterosigma akashiwo, although some individuals of both species were observed ingesting H. akashiwo in the initial incubation period. The relationship between prey cell volume and ingestion rate could be expressed mathematically for both Favella species, indicating that it is possible to estimate the potential feeding activity of each Favella species on specific algae using an equation, and may be applicable to evaluate the food value of prey alga for both Favella species. When F. taraikensis was fed mixtures of H. circularisquama and Pavlova lutheri, significant ingestion rates of H. circularisquama by F. taraikaensis could not be measured when H. circularisquama accounted for less than 20% of the other prey biomass. However, clear selectivity for H. circularisquama was observed when H. circularisquama reached and exceeded 34% of the other prey biomass. Under mixed prey conditions, it is likely that the selectivity of F. taraikaensis is stronger for larger prey compared to prey algae with a size near the lower limit on which F. taraikaensis can feed.

Journal Article↗
PubMed2001

New insights into actions of the renin-angiotensin system in the kidney: concentrating on the Ang II receptors and the newly described Ang-(1-7) and its receptor.

Angiotensin II (Ang II), the physiologically active component of the renin-angiotensin system (RAS), plays an important role in the regulation of the renal function. Based on their different pharmacologic and biochemical properties, 2 distinct subtypes of Ang II receptor have been defined and designated as type 1 (AT(1)) and type 2 (AT(2)) receptors. Most of the well-characterized actions of Ang II are now generally considered to result from stimulation of AT(1) receptors, whereas AT(2) receptors may exert opposite effects against AT(1) receptors. In the kidney, activation of the AT(2) receptor has been reported to regulate pressure-natriuresis and to stimulate the production of nitric oxide, bradykinin, or epoxyeicosatrienoic acids, which may cause vasodilation and modulate the vasoconstrictor action mediated by AT(1) receptors. In addition, recent studies have reported that Ang II exerts important effects on the normal renal development through both AT(1) and AT(2) receptors. Finally, other Ang fragments such as Ang-(1-7) are also involved in the actions of RAS in the kidney. In this review article, we will summarize results obtained from recent studies on the AT(1) and AT(2) receptor-mediated action of Ang II in the kidney. Renal actions of Ang-(1-7), which often oppose against those of Ang II, are also discussed.

Angiotensin I↗
PubMed2001

Transcriptional suppression of type 1 angiotensin II receptor gene expression by peroxisome proliferator-activated receptor-gamma in vascular smooth muscle cells.

Angiotensin (A) II plays a critical role in vascular remodeling, and its action is mediated by type 1 AII receptor (AT1R). Recently, 15-deoxy-(Delta)(12,14)-prostaglandin J(2) and thiazolidinediones have been shown to be ligands for peroxisome proliferator-activated receptor (PPAR)-gamma and activate PPAR-gamma. In the present work, we have studied the effect of PPAR-gamma on AT1R expression in rat vascular smooth muscle cells (VSMCs). We observed that: 1) endogenous AT1R expression was significantly decreased by PPAR-gamma ligands both at messenger RNA and protein levels, whereas AT1R messenger RNA stability was not affected; 2) AII-induced increase of (3)H-thymidine incorporation into VSMCs was inhibited by PPAR-gamma ligands; 3) rat AT1R gene promoter activity was significantly suppressed by PPAR-gamma ligands, and PPAR-gamma overexpression further suppressed the promoter activity; 4) transcriptional analyses using AT1R gene promoter mutants revealed that a GC-box-related sequence within the -58/-34 region of the AT1R gene promoter was responsible for the suppression; 5) Sp1 overexpression stimulated AT1R gene transcription via the GC-box-related sequence, which was inhibited by additional PPAR-gamma overexpression; 6) electrophoretic mobility shift assay suggested that Sp1 could bind to the GC-box-related sequence whereas PPAR-gamma could not; 7) antibody supershift experiments using VSMC nuclear extracts revealed that protein-DNA complexes formed on the GC-box-related sequence, which were decreased by PPAR-gamma coincubation, were mostly composed of Sp1; and 8) glutathione S-transferase pull-down assay revealed a direct interaction between PPAR-gamma and Sp1. Taken together, it is suggested that activated PPAR-gamma suppresses AT1R gene at a transcriptional level by inhibiting Sp1 via a protein-protein interaction. PPAR-gamma ligands, thus, may inhibit AII-induced cell growth and hypertrophy in VSMCs by AT1R expression suppression and possibly be beneficial for treatment of diabetic patients with hypertension and atherosclerosis.

Angiotensin II↗
PubMed2001

Synthesis of cis- and trans-5,8-dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone.

Cis- and trans-5,8-dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone (1a, 1b) were for the first time synthesized from 5,8-dihydroxy-1,4-naphthoquinone (naphthazazine) (6) as a starting material and racemic triol (3) was first synthesized from 7. The configuration of 1a was determined by X-ray analysis.

Crystallography, X-Ray↗
PubMed2001

Differential effects among thiazolidinediones on the transcription of thromboxane receptor and angiotensin II type 1 receptor genes.

Peroxisome proliferator-activated receptor (PPAR)-gamma ligands thiazolidinediones (TZDs) have recently been reported to be anti-hypertensive and anti-atherosclerotic. We have previously shown that one of the TZDs troglitazone significantly suppressed the transcription of both thromboxane receptor (TXR) and angiotensin II type 1 receptor (AT1R) genes in vascular smooth muscle cells (VSMCs) by activating PPAR-gamma. In the present study, we compared the effects of troglitazone and other TZDs on the transcription of these genes. TXR and AT1R mRNAs in rat VSMCs were determined by semi-quantitative RT-PCR. Luciferase chimeric constructs containing either the 989-bp rat TXR gene promoter or the 1,969-bp rat AT1R gene promoter were transiently transfected into VSMCs. The cells were incubated with troglitazone, RS-1455 (a derivative of troglitazone which does not contain the hindered phenol resembling alpha-tocopherol), pioglitazone, or rosiglitazone for 12 h before harvesting. mRNA expression levels of TXR and AT1R were significantly decreased by troglitazone in contrast to rosiglitazone. TXR gene and AT1R gene transcription was significantly suppressed by troglitazone in a dose-dependent manner, while RS-1455 was less potent. Pioglitazone and rosiglitazone weakly suppressed the transcription of both genes in a manner almost similar to RS-1455. We have shown that troglitazone suppresses transcription of both the TXR and AT1R genes more potently than other TZDs. The structure of troglitazone and RS-1455 is identical except the hindered phenol, which is recently recognized to function as an antioxidant. Moreover, we have shown that the potency for activating PPAR-gamma is almost identical between troglitazone and RS-1455. We therefore speculate that the strong transcriptional suppression of the TXR and AT1R genes by troglitazone may be mediated in part by its antioxidant effect.

Animals↗
PubMed2001

Involvement of cytochrome P450 metabolites in the vascular action of angiotensin II on the afferent arterioles.

Recent studies have demonstrated that cytochrome P450-dependent metabolites of arachidonic acid (CYP450-AA) play important roles in the control of renal vascular resistance (RVR). In the present study, we examined the possible involvement of CYP450-AA in the vasoconstrictor action of angiotensin II (Ang II) on the afferent arterioles (Af-Arts), a vascular segment crucial to the control of RVR. Rabbit Af-Arts were microperfused at 60 mmHg in vitro, and the vasoconstrictor action of Ang II (10(-11)-10(-8) M, added to both the bath and lumen) was examined with or without blocking the activity of CYP450 epoxygenase or hydroxylase. Ang II decreased the luminal diameter of Af-Arts in a dose-dependent manner (34+/-2% of control diameter at 10(-8) M, n=9, p<0.0001). Pretreatment with miconazole, an inhibitor of CYP450 epoxygenase, at 10(-6) M decreased the basal diameter by 14+/-1% (n=6, p<0.01) and augmented the vasoconstrictor action of Ang II (7+/-3% of control diameter at 10(-8) M, p<0.001 vs. without miconazole). This augmentation was abolished by blocking the Ang II type 2 (AT2) receptor with PD 123319 at 10(-7) M. In contrast, pretreatment with 17-octadecynoic acid (17-ODYA, 10(-6) M), which inhibits both epoxygenase and hydroxylase activity, had no effect on the basal diameter but attenuated the vasoconstrictor action of Ang 11(46+/-2% of control diameter at 10(-8) M, p<0.01 vs. without 17-ODYA). Our results demonstrate that in the Af-Art, endogenous CYP450-AA are involved not only in the control of basal tone but also in the action of Ang II. Further, it appears that the CYP450 epoxygenase pathway attenuates Ang II action via AT2 receptors.

Angiotensin II↗
PubMed2000

Suppression of rat thromboxane synthase gene transcription by peroxisome proliferator-activated receptor gamma in macrophages via an interaction with NRF2.

We have studied the transcription regulation of the rat thromboxane synthase (TXS) gene by peroxisome proliferator-activated receptor gamma (PPARgamma) in macrophages. The transcription activity of a cloned 5'-flanking region (1.6 kilobases) of the rat TXS gene (5'FL-TXS) was examined by luciferase reporter gene assay. TXS mRNA expression and the transcription activity of 5'FL-TXS were inhibited by PPARgamma ligands, 15-deoxy-Delta(12,14)-prostaglandin J(2) (PGJ(2)), and the thiazolidinedione troglitazone (TRO) in a dose-dependent manner. Overexpression of PPARgamma also significantly suppressed transcription, and further addition of PGJ(2) or TRO augmented the suppression. Deletion analysis showed that the element responsible for the PPARgamma effect is located in a region containing the nuclear factor E2 (NF-E2)/AP-1 site (-98/-88), which was indicated to be the major promoter of the TXS gene. By electrophoretic mobility shift assay using the NF-E2/AP-1 site and nuclear extracts from macrophages, we observed a specific protein-DNA complex formation, which was inhibited by a specific antibody against the transcription factor NRF2 (NF-E2-related factor 2). Moreover, the complex was decreased with PGJ(2), TRO, or in vitro translated PPARgamma. The transcription suppression by PPARgamma was confirmed using this truncated NRF2-binding element (-98/-88) by the reporter gene assay. Finally, a direct interaction between PPARgamma and NRF2 was confirmed by glutathione S-transferase pull-down assay. In conclusion, the NRF2-binding site (-98/-88) is the major promoter of 5'FL-TXS which can be suppressed by activated PPARgamma via a protein-protein interaction with NRF2 in macrophages.

Animals↗
PubMed2000

Endogenous nitric oxide and epoxyeicosatrienoic acids modulate angiotensin II-induced constriction in the rabbit afferent arteriole.

Nitric oxide (NO) and epoxyeicosatrienoic acids (EETs), cytochrome P450 epoxygenase metabolites of arachidonic acid, are released by the vascular endothelium and play important roles in the control of glomerular haemodynamics. We examined whether endogenous NO or EETs modulate angiotensin II- (AngII) induced constriction in isolated microperfused afferent arteriole (Af-Art) of the rabbit kidney. When Af-Arts were treated with NG-nitro-L-arginine methyl ester (L-NAME, an inhibitor of NO synthese; 10-4 mol L-1) or miconazole (an inhibitor of P450 epoxygenase; 10-6 mol L-1), basal diameter was decreased by 34.5 +/- 2.2 and 13.9 +/- 3.2%, respectively. AngII added to both the bath and lumen decreased the diameter of Af-Arts in a dose-dependent manner. Pretreatment with either L-NAME or miconazole also augmented the constrictor response to AngII. AngII at 10-8 mol L-1 decreased the diameter to 39.2 +/- 1.4, 32.9 +/- 3.6, and 12.7 +/- 4.6%, in control, L-NAME-, and miconazole-treated group, respectively. In order to study whether the AngII type2 (AT2) receptor modulates AngII action via NO or EETs, we repeated the experiments in the presence of PD123319 (an AT2 receptor antagonist; 10-7 mol L-1). In the presence of PD123319, L-NAME still augmented the constrictor response to AngII, however, miconazole had no effect. In the presence of PD123319, AngII at 10-8 mol L-1 decreased the diameter to 25.0 +/- 4.6, 9.4 +/- 4.0, and 26.0 +/- 3.3%, in control, L-NAME-, and miconazole-treated group, respectively. These results suggest that (1) tonic release of NO and EETs attenuates the vasoconstrictor response to AngII in Af-Arts and (2) AT2 receptor seems to be coupled to EETs rather than the NO pathway.

8,11,14-Eicosatrienoic Acid↗
PubMed2000

Phlebosclerotic colitis: value of radiography in diagnosis--report of three cases.

Three cases sharing the following radiologic features are reported: (a) abdominal conventional radiography-vascular calcifications at the right hemicolon, (b) abdominal computed tomography-colonic wall thickening and venous calcifications, and (c) barium enema examination-luminal narrowing of the right hemicolon and thumbprinting. There were no clinical or laboratory findings suggestive of portal hypertension. The disease entity, "phlebosclerotic colitis," should be differentiated from ordinary ischemic colitis.

Abdomen, Acute↗
PubMed2000

Effects of clarithromycin on rheological properties of nasal mucus in patients with chronic sinusitis.

Macrolide antibiotics have a variety of actions along with antimicrobial action. To determine the effects of oral administration of clarithromycin (CAM) on rheological properties, we measured the spinability, dynamic viscoelasticity, and solid composition of human nasal mucus from 18 patients with chronic sinusitis before and after administration of CAM for 4 weeks. After administration of CAM, the spinability and percent solid composition of nasal mucus increased from 26.5 +/- 12.2 mm to 40.2 +/- 18.7 mm and 7.86% +/- 3.47% to 13.90% +/- 3.67% (p < .05), respectively, whereas the ratio of the viscosity to the elasticity (eta'/G') of nasal mucus after the administration of CAM decreased in all of the mucus samples. These results suggest that treatment with CAM may modulate the rheological properties of nasal mucus in patients with chronic sinusitis.

Adolescent↗
PubMed2000

[Study on endoscopic sinus surgery management of chronic sinusitis with nasal polyps].

Endoscopic sinus surgery is commonly used to treat chronic sinusitis. Subjects were 79 chronic sinusitis patients--50 men and 29 women aged 17 to 79 years (average: 50.6 years) undergoing endoscopic sinus surgery in our department from January 1993 to December 1997. Mean follow-up was 17.5 months. We evaluated preoperative staging of chronic sinusitis based on Kennedy staging. Most were stage 3. This type of staging was not effective in predicting nasal polyp relapse. We found that cases with diffuse polyposis and associated disease such as bronchial asthma or aspirin-induced asthma tended to experience a polyp relapse. Our results suggest that postoperative treatment is important in maintaining patency of the ostiomeatal complex, nasal polyp or edematous mucosa relapse must be treated early in on in occurrence.

Adolescent↗
PubMed2000

[Thymidylate synthase activity after preoperative administration of 5-FU in patients with gastric or colorectal cancer].

Continuous intravenous injection of 5-FU was given at 300 mg/m2 to patients with gastric or colorectal cancer for consecutive 3 days preoperatively, and the relationships between the time until collection of samples (from final administration of 5-FU to excision of tissue samples) and total thymidylate synthase (TS total) activity, free thymidylate synthase (TS free) activity, thymidylate synthase inhibition rate (TSIR), thimidine kinase (TK) activity, and tissue 5-FU and FdUMP concentrations investigated. TS total was shown to gradually reduce with time, but the relationship between time and the other assay items could not be identified due to large variability in the data. TS total and TK also proved to be affected also by the sites at which the samples were collected, and exhibited significantly higher enzyme activity in tumor tissue than that in normal tissue.

Adult↗
PubMed1999

Neuronal differentiation of neuro 2a cells by inhibitors of cell cycle progression, trichostatin A and butyrolactone I.

Trichostatin A (TSA, 17 nM), a specific and reversible inhibitor of histone deacetylase induced neurite network formation at and after 4 days. The networks were preserved for at least 3 weeks in the presence of TSA. Butyrolactone I (BLI, 23.6 microM), an inhibitor of cdc2 and cdk2 kinases, also induced neurite extension. Both compounds enhanced the acetylcholinesterase activity of the cells. Cell cycle progression of the cells was blocked by TSA (17 nM) at G1 phase alone. Furthermore, the level of histone hyperacetylation and p21(WAF1) expression in TSA-treated cells increased transiently. These findings suggest that the induction of the neuronal differentiation in Neuro 2a cells by these agents requires the cell cycle arrest at G1 phase, which is caused by inhibition of cycline dependent kinase, a target molecule of BLI and p21(WAF1).

4-Butyrolactone↗
PubMed1999

Effects of mucokinetic drugs on rheological properties of reconstituted human nasal mucus.

OBJECTIVE: To investigate the effects of mucokinetic drugs on the rheological properties of human nasal mucus in patients with chronic sinusitis. DESIGN: We reconstituted human nasal mucus obtained from 74 patients with chronic sinusitis and determined the effects of 4 mucokinetic drugs, including acetylcysteine, deoxynuclease I, 2% sodium bicarbonate, and a combination product containing tyloxapol (Alevaire), on rheological properties of reconstituted human nasal mucus (RHNM). We used 5% RHNM dissolved in phosphate-buffered solution as the optimal buffer and concentration of RHNM for the study because it showed a viscoelastic response similar to that of freshly collected nasal mucus from patients with chronic sinusitis. METHODS: Four experiments were performed to determine the influence of each drug on dynamic viscosity and elasticity of 5% RHNM. Distilled water was used as a control. RESULTS: Acetylcysteine and deoxynuclease I significantly decreased both dynamic viscosity and elastic modulus, while distilled water had no effect on rheological properties of 5% RHNM in vitro. Alevaire significantly reduced both dynamic viscosity and elastic modulus. Sodium bicarbonate significantly reduced elastic modulus but not dynamic viscosity. Reduction of elastic modulus by Alevaire was significantly greater than that by sodium bicarbonate, while there was no difference in reduction of dynamic viscosity between them. CONCLUSION: Our results indicate that RHNM may be useful for studying the topical effects of various drugs on nasal mucus from patients with chronic sinusitis.

Acetylcysteine↗
PubMed1999

An evaluation of malignancy and prognostic factors based on mode of lymph node metastasis in esophageal carcinoma.

This study was conducted to evaluate lymph node metastasis as a key prognostic factor in esophageal cancer. Metastatic lesions in lymph nodes were grouped by histological morphology as intracapsular or extracapsular, and the significance of lymph node metastasis was evaluated by relating metastatic lesions to clinical pathologic factors and patient prognosis. In our hospital, 46 of 81 patients who underwent resection of esophageal cancer developed lymph node metastasis. These 46 patients were enrolled in a study analyzing the relationship between the metastatic mode and the clinicopathological factors. The frequency of extracapsular metastasis was significantly high in patients with a profound depth of cancer, three or more metastases, distant metastasis (n3 and n4), or severe lymphatic invasion. The prognosis was significantly worse in patients with extracapsular metastasis, and this tendency was also seen even in patients with three or more metastases, limited metastasis (n1 and n2), or mild lymphatic invasion (ly0 and ly1). These findings suggest that the metastatic mode reflects the degree of esophageal cancer progression and is an important prognostic factor.

Aged↗