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1.
Radiography (Lond) ; 28(4): 912-918, 2022 11.
Article in English | MEDLINE | ID: mdl-35810623

ABSTRACT

INTRODUCTION: We have developed a novel radiopaque tiltmeter (ROT) that can indicate patient tilt during a radiography examination and display it on X-ray images. This study evaluated the effect of variation of patient tilt on the reproducibility of Fowler's position for chest radiography and the accuracy of the ROT. METHODS: We evaluated the reproducibility of Fowler's position based on changes from the first day in the central venous catheter (CVC) tip position and the cardiothoracic ratio (CTR) with and without a digital tiltmeter to verify its efficacy in patients who underwent mobile chest radiography. The ROT contains radiopaque liquid consisting of white barium sulfate solution and oil and has a scale bar of 15°-75° with increments of 15° to indicate ROT tilt. The ROT tilt was increased from 10° to 80° in increments of 10°. We then evaluated (1) the difference between the ROT tilt and the tilt measured with a digital tiltmeter, and (2) the ROT tilt displayed on the X-ray image. RESULTS: With regard to reproducibility in Fowler's position, changes in the CVC tip position were 2.8 ± 3.9 mm and 10.7 ± 10.6 mm with and without the tiltmeter, respectively (p < 0.05) and the respective rates of change in the CTR were 0.7% ± 0.6% and 4.0% ± 2.1% (p < 0.05). Differences between the ROT tilt and the tilt measured by the digital tiltmeter were within ±2.5°. All ROT tilts displayed on the X-ray images were recognized exactly as each tilt. CONCLUSION: Our novel ROT had the potential to accurately indicate patient tilt during chest radiography, which could be helpful in terms of reproducibility and precise follow-up. IMPLICATIONS FOR PRACTICE: Use of the ROT for determination of patient tilt can improve reproducibility in Fowler's position, allowing more accurate serial X-ray imaging.


Subject(s)
Barium Sulfate , Humans , Radiography , Reproducibility of Results
2.
Pharmeur Sci Notes ; 2006(1): 47-9, 2006 Aug.
Article in English | MEDLINE | ID: mdl-17694647

ABSTRACT

Tri-PEC (IPEC-Americas, IPEC-Europe and JPEC) carried out a two-way analysis of variance (Round Robin testing) for the assay of Anhydrous Dibasic Calcium Phosphate (CaHPO4) at the request of the Pharmacopoeial Discussion Group (PDG). On the basis of the result obtained, the difference in the assay results for anhydrous CaHPO4 using the different methods of the 3 Pharmacopoeias was not significant, while the difference in the results for the 3 different batch samples tested by 3 different methods was significant (p < 0.05). On the basis of these results, the methods from the 3 Pharmacopoeias, did not give different results, and thus the methods themselves should be considered equivalent.


Subject(s)
Calcium Phosphates/analysis , Pharmacopoeias as Topic , Analysis of Variance , Europe , Japan , Quality Control , Titrimetry , United States
3.
Plant Mol Biol ; 47(3): 413-21, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11587512

ABSTRACT

High-resolution fluorescence in situ hybridization (FISH) on interphase and pachytene nuclei, and extended DNA fibers enabled microscopic distinction of DNA sequences less than a few thousands of base pairs apart. We applied this technique to reveal the molecular organization of telomere ends in japonica rice (Oryza sativa ssp. japonica), which consist of the Arabidopsis type TTTAGGG heptameric repeats and the rice specific subtelomeric tandem repeat sequence A (TrsA). Southern hybridizations of DNA digested with Bal31 and EcoRI, and FISH on chromosomes and extended DNA fibers demonstrated that (1) all chromosome ends possess the telomere tandem repeat measuring 3-4 kb; (2) the subtelomeric TrsA occurs only at the ends of the long arms of chromosomes 6 and 12, and measure 6 and 10 kb, which corresponds to 231 and 682 copies for these sites, respectively; (3) the telomere and TrsA repeats are separated by at most a few thousands of intervening nucleotide sequences. The molecular organization for a general telomere organization in plant chromosomes is discussed.


Subject(s)
Chromosomes/genetics , DNA, Plant/genetics , Oryza/genetics , Chromosome Painting , In Situ Hybridization, Fluorescence/methods , Repetitive Sequences, Nucleic Acid , Telomere/genetics
4.
Toxicol Pathol ; 29(4): 458-66, 2001.
Article in English | MEDLINE | ID: mdl-11560251

ABSTRACT

To evaluate the transgenic mouse carrying a human prototype c-Ha-ras gene (rasH2 mouse) as a model for 26-week carcinogenicity tests, Di(2-ethylhexyl)phthalate (DEHP), a peroxisome proliferator, was administered to 15 rasH2 mice/sex/group at concentrations of 1,500, 3,000 or 6,000 ppm, and to 15 wild-type (non-Tg) mice/sex/group at a concentration of 6,000 ppm in their diets for 26 weeks. Survival rates and food consumption in the groups treated with DEHP and in the control group were similar. Body weight gain in rasH2 and non-Tg mice at 6,000 ppm in the terminal week decreased about 10% as compared to the control group. Common findings related to treatment with DEHP in rasH2 and non-Tg mice included hypertrophy with coarse granules and deposit of pigment in the liver, hydronephrosis and tubular regeneration in the kidney, focal atrophy in the testis, and increased eosinophilic body in the nasal cavity. Hepatocellular adenoma was induced by treatment with DEHP, and was confined to male rasH2; mice the incidence being 7%(1/15), 13%(2/15), and 27%(4/15) in the 1,500-, 3,000-, and 6,000-ppm group, respectively. Point mutation was not detected in codon 12 and 61 of human c-Ha-ras transgene upon DNA analyses on frozen samples taken from these hepatocellular adenomas. From the results obtained in this 26-week carcinogenicity study, it is concluded that DEHP is a hepato-carcinogen for transgenic mouse carrying a human prototype c-Ha-ras gene.


Subject(s)
Adenoma, Liver Cell/genetics , Diethylhexyl Phthalate/toxicity , Genes, ras , Liver Neoplasms, Experimental/genetics , Peroxisome Proliferators/toxicity , Adenoma, Liver Cell/chemically induced , Adenoma, Liver Cell/pathology , Administration, Oral , Animals , Carcinogenicity Tests/methods , Diethylhexyl Phthalate/administration & dosage , Dose-Response Relationship, Drug , Female , Kidney/drug effects , Kidney/pathology , Kidney Tubules/drug effects , Kidney Tubules/pathology , Liver/drug effects , Liver/pathology , Liver Neoplasms, Experimental/chemically induced , Liver Neoplasms, Experimental/pathology , Male , Mice , Mice, Transgenic , Nasal Cavity/drug effects , Nasal Cavity/pathology , Peroxisome Proliferators/administration & dosage , Polymorphism, Single-Stranded Conformational , Sex Factors , Survival Rate , Testis/drug effects , Testis/pathology , Time Factors
5.
Chem Pharm Bull (Tokyo) ; 49(6): 699-702, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11411519

ABSTRACT

From aerial parts of Tripterospermum japonicum, 6'-O-beta-D-glucopyranosylmorroniside, benzophenone glucoside, named triptephenoside and 2'''- and 4'''-O-acetyl-2''-O-alpha-L-rhamnopyranosylisovitexins were isolated, along with known iridoid and secoiridoid glucosides, and C-glycosyl flavones.


Subject(s)
Benzophenones/chemistry , Flavonoids/chemistry , Glycosides/isolation & purification , Acylation , Glycosides/chemistry , Molecular Structure , Spectrum Analysis
6.
J Microsc ; 202(Pt 1): 255-60, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11298902

ABSTRACT

Spin-sensitive optical near-field microscopy and spectroscopy are proposed based on the study on the conserved quantities in optical near-field interactions of atoms with dielectric surfaces. A two-step photoionization spectra of Cs atoms resolving hyperfine structures are demonstrated near a planar dielectric surface by using evanescent waves. These techniques of state/spin-selective excitation and highly sensitive detection, combined with the techniques of optical pumping, will open up possibilities of space- and polarization-sensitive detection of optical near-fields using atomic probes. This novel method provides us with a useful technique for the observation of polarization nature of the optical near-field and controlling the spin states of mesoscopic electronic systems.

8.
Arch Gynecol Obstet ; 264(1): 47-8, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10985623

ABSTRACT

We present a case of polymyositis (PM) following intrauterine fetal death. The first presentation of PM in the patient was during postpartum. The patient was referred to our hospital because of a fever of unknown cause 13 d after delivery of dead fetus at 32 weeks' gestation. PM was diagnosed based on the increased serum creatine phosphokinase level, typical electromyogram findings and characteristic muscle biopsy findings.


Subject(s)
Fetal Death/complications , Polymyositis/complications , Puerperal Disorders/complications , Adult , Biopsy , Creatine Kinase/blood , Electromyography , Female , Humans , Muscle, Skeletal/pathology , Polymyositis/diagnosis , Puerperal Disorders/diagnosis
9.
Mol Gen Genet ; 263(3): 388-94, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10821172

ABSTRACT

This paper describes a fluorescence in situ hybridization (FISH) analysis of three different repetitive sequence families, which were mapped to mitotic metaphase chromosomes and extended DNA fibers (EDFs) of the two subspecies of rice (OrYza sativa), indica and japonica (2n = 2x = 24). The repeat families studied were (1) the tandem repeat sequence A (TrsA), a functionally non-significant repeat; (2) the [TTTA-GGG]n telomere sequence, a non-transcribed, tandemly repeated but functionally significant repeat; and (3) the 5S ribosomal RNA (5S rDNA). FISH of the TrsA repeat to metaphase chromosomes of indica and japonica cultivars revealed clear signals at the distal ends of twelve and four chromosomes, respectively. As shown in a previous report, the 17S ribosomal RNA genes (17S rDNA) are located at the nucleolus organizers (NORs) on chromosomes 9 and 10 of the indica cultivar. However, the japonica rice lacked the rDNA signals on chromosome 10. The size of the 5S rDNA repeat block, which was mapped on the chromosome 11 of both cultivars, was 1.22 times larger in the indica than in the japonica genome. The telomeric repeat arrays at the distal ends of all chromosome arms were on average three times longer in the indica genome than in the japonica genome. Flow cytometric measurements revealed that the nuclear DNA content of indica rice is 9.7% higher than that of japonica rice. Our data suggest that different repetitive sequence families contribute significantly to the variation in genome size between indica and japonica rice, though to different extents. The increase or decrease in the copy number of several repetitive sequences examined here may indicate the existence of a directed change in genome size in rice. Possible reasons for this phenomenon of concurrent evolution of various repeat families are discussed.


Subject(s)
DNA, Plant , Genome, Plant , Oryza/genetics , Repetitive Sequences, Nucleic Acid , Blotting, Southern , Flow Cytometry , Genes, Plant , In Situ Hybridization, Fluorescence , RNA, Ribosomal, 5S/genetics , Species Specificity , Tandem Repeat Sequences , Telomere/genetics
10.
Chem Pharm Bull (Tokyo) ; 47(9): 1341-3, 1999 Sep.
Article in English | MEDLINE | ID: mdl-10517014

ABSTRACT

As a part of the search for biologically active plant products, M cells, which form a collagen fiber network in vitro after a prolonged culture period, were used. The n-BuOH-soluble fraction of a methanol extract of leaves of Premna subscandens exhibited promotion of collagen network formation by M cells. Extensive isolation work guided by a bioassay afforded a phenylethanoid, acteoside, as an active compound.


Subject(s)
Collagen/metabolism , Plants, Medicinal/chemistry , Cell Line , Coloring Agents , Humans , Magnetic Resonance Spectroscopy , Philippines , Plant Extracts/pharmacology , Plant Leaves/chemistry , Stimulation, Chemical
11.
Toxicol Lett ; 109(1-2): 105-14, 1999 Sep 20.
Article in English | MEDLINE | ID: mdl-10514036

ABSTRACT

A collaborative study was conducted to evaluate whether a replicative DNA synthesis (RDS) test using the rat liver can detect nongenotoxic (Ames-negative) hepatocarcinogens with three or seven daily administrations at dose-levels effective in long-term bioassays. The assay methods were well-validated by the 14 participants. Of six compounds tested, carbon tetrachloride (50 and 100 mg/kg), clofibrate (125 and 250 mg/kg), diethylstilbestrol (0.125 and 0.25 mg/kg) and urethane (100 mg/kg) gave positive results, methyl carbamate (200 and 400 mg/kg) exerted equivocal effects, and D,L-ethionine (125 mg/kg) failed to elevate RDS. These findings suggest that the RDS test can detect many nongenotoxic rat hepatocarcinogens with short-term administration at dose-levels used in long-term bioassays.


Subject(s)
Carcinogenicity Tests/methods , DNA Replication/drug effects , DNA/biosynthesis , Liver/metabolism , Mutagenicity Tests/methods , Animals , Antimetabolites, Antineoplastic/toxicity , Bromodeoxyuridine/toxicity , Immunohistochemistry , Liver/cytology , Liver/drug effects , Male , Rats , Rats, Inbred F344
12.
Fetal Diagn Ther ; 14(4): 240-3, 1999.
Article in English | MEDLINE | ID: mdl-10420049

ABSTRACT

OBJECTIVE: Fetal plasma prostaglandin F(2alpha) (PGF(2alpha)) and cortisol responses to fetal endotoxin administration were evaluated in late-gestation goats (n = 9). METHODS: After endotoxin (Escherichia coli, O111:B4 lipopolysaccharide) administration, fetal plasma PGF(2alpha) and cortisol levels, fetal blood gases and pH were measured periodically. RESULTS: After endotoxin administration, fetal plasma cortisol levels increased to 9.8 +/- 1.4 and 9.4 +/- 1. 2 ng/ml after 1 and 3 h, respectively (p < 0.05) and PGF(2alpha) levels did not change throughout the study. CONCLUSIONS: These results suggest that absent PGF(2alpha) and attenuated cortisol responses to fetal endotoxin administration, relative to the adult, may be a self-protective mechanism which diminishes the likelihood of premature delivery.


Subject(s)
Dinoprost/blood , Fetal Blood/metabolism , Hydrocortisone/blood , Lipopolysaccharides/toxicity , Animals , Drug Resistance , Escherichia coli/pathogenicity , Female , Gestational Age , Goats , Lipopolysaccharides/administration & dosage , Obstetric Labor, Premature/prevention & control , Pregnancy
13.
Circ Res ; 83(10): 1035-46, 1998 Nov 16.
Article in English | MEDLINE | ID: mdl-9815151

ABSTRACT

The expression pattern of angiotensin (Ang) II type 2 receptor (AT2-R) in the remodeling process of human left ventricles (LVs) remains poorly defined. We analyzed its expression at protein, mRNA, and cellular levels using autopsy, biopsy, or operation LV samples from patients with failing hearts caused by acute (AMI) or old (OMI) myocardial infarction and idiopathic dilated cardiomyopathy (DCM) and also examined functional biochemical responses of failing hearts to Ang II. In autopsy samples from the nonfailing heart group, the ratio of AT1-R and AT2-R was 59% and 41%, respectively. The expression of AT2-R was markedly increased in DCM hearts at protein (3.5-fold) and mRNA (3.1-fold) levels compared with AMI or OMI. AT1-R protein and mRNA levels in AMI hearts showed 1.5- and 2.1-fold increases, respectively, whereas in OMI and DCM hearts, AT1-R expression was significantly downregulated. AT1-R-mediated response in inositol phosphate production was significantly attenuated in LV homogenate from failing hearts compared with nonfailing hearts. AT2-R sites were highly localized in the interstitial region in either nonfailing or failing heart, whereas AT1-R was evenly distributed over myocardium at lower densities. Mitogen-activated protein kinase (MAPK) activation by Ang II was significantly decreased in fibroblast compartment from the failing hearts, and pretreatment with AT2-R antagonist caused an additional significant increase in Ang II-induced MAPK activity (36%). Cardiac hypertrophy suggested by atrial and brain natriuretic peptide levels was comparably increased in OMI and DCM, whereas accumulation of matrix proteins such as collagen type 1 and fibronectin was much more prominent in DCM than in OMI. These findings demonstrate that (1) AT2-R expression is upregulated in failing hearts, and fibroblasts present in the interstitial regions are the major cell type responsible for its expression, (2) AT2-R present in the fibroblasts exerts an inhibitory effect on Ang II-induced mitogen signals, and (3) AT1-R in atrial and LV tissues was downregulated during chronic heart failure, and AT1-R-mediated functional biochemical responsiveness was decreased in the failing hearts. Thus, the expression level of AT2-R is likely determined by the extent of interstitial fibrosis associated with heart failure, and the expression and function of AT1-R and AT2-R are differentially regulated in failing human hearts.


Subject(s)
Endomyocardial Fibrosis/metabolism , Myocardium/pathology , Receptors, Angiotensin/genetics , Up-Regulation/physiology , Adult , Autopsy , Biopsy , Blotting, Northern , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Cardiomyopathy, Dilated/metabolism , Cardiomyopathy, Dilated/pathology , Endomyocardial Fibrosis/physiopathology , Female , Fibroblasts/chemistry , Fibroblasts/pathology , Gene Expression/physiology , Heart Failure/metabolism , Heart Failure/pathology , Heart Ventricles/chemistry , Heart Ventricles/enzymology , Heart Ventricles/pathology , Humans , Hypertrophy, Left Ventricular/metabolism , Hypertrophy, Left Ventricular/pathology , Inositol Phosphates/metabolism , Male , Middle Aged , Myocardial Infarction/metabolism , Myocardial Infarction/pathology , Myocardium/chemistry , Myocardium/enzymology , RNA, Messenger/metabolism , Receptor, Angiotensin, Type 1 , Receptor, Angiotensin, Type 2
14.
Circulation ; 97(19): 1952-9, 1998 May 19.
Article in English | MEDLINE | ID: mdl-9609089

ABSTRACT

BACKGROUND: Many studies have suggested that the renin-angiotensin system plays an important role in the development of pressure overload-induced cardiac hypertrophy. Moreover, it has been reported that pressure overload-induced cardiac hypertrophy is completely prevented by ACE inhibitors in vivo and that the stored angiotensin II (Ang II) is released from cardiac myocytes in response to mechanical stretch and induces cardiomyocyte hypertrophy through the Ang II type 1 receptor (AT1) in vitro. These results suggest that the AT1-mediated signaling is critical for the development of mechanical stress-induced cardiac hypertrophy. METHODS AND RESULTS: To determine whether AT1-mediated signaling is indispensable for the development of pressure overload-induced cardiac hypertrophy, pressure overload was produced by constricting the abdominal aorta of AT1A knockout (KO) mice. Quantitative reverse transcriptase-polymerase chain reaction revealed that the cardiac AT1 (probably AT1B) mRNA levels in AT1A KO mice were <10% of those of wild-type (WT) mice and were not affected by pressure overload. Chronic treatment with subpressor doses of Ang II increased left ventricular mass in WT mice but not in KO mice. Pressure overload, however, fully induced cardiac hypertrophy in KO as well as WT mice. There were no significant differences between WT and KO mice in expression levels of fetal-type cardiac genes, in the left ventricular wall thickness and systolic function as revealed by the transthoracic echocardiogram, or in the histological changes such as myocyte hypertrophy and fibrosis. CONCLUSIONS: AT1-mediated Ang II signaling is not essential for the development of pressure overload-induced cardiac hypertrophy.


Subject(s)
Angiotensin II/pharmacology , Blood Pressure , Cardiomegaly/physiopathology , Receptors, Angiotensin/deficiency , Animals , Aorta, Abdominal/physiology , Blood Pressure/drug effects , Cardiomegaly/etiology , Cardiomegaly/genetics , Echocardiography , Hypertension/complications , Hypertension/physiopathology , Mice , Mice, Knockout , Polymerase Chain Reaction , RNA, Messenger/biosynthesis , Receptor, Angiotensin, Type 1 , Receptors, Angiotensin/biosynthesis , Receptors, Angiotensin/genetics , Receptors, Angiotensin/physiology , Signal Transduction , Transcription, Genetic
15.
Circ Res ; 82(7): 779-85, 1998 Apr 20.
Article in English | MEDLINE | ID: mdl-9562437

ABSTRACT

Increasing evidence has suggested that locally produced angiotensin II (Ang II) plays an important role in the development of cardiac hypertrophy through the Ang II type 1 receptor (AT1). We and others have recently reported that Ang II is critical for mechanical stress-induced hypertrophic responses in vitro. Using AT1a knockout (KO) mice, we examined whether Ang II is indispensable for pressure overload-induced cardiac hypertrophy in the present study. Reverse-transcriptase polymerase chain reaction analysis revealed that AT1 mRNA levels were <10% in the heart of KO mice compared with wild-type (WT) mice, but the Ang II type 2 receptor gene was expressed at almost the same levels in the hearts of both mice. Intravenous infusion of subpressor dose of Ang II induced c-fos gene expression in the hearts of WT mice but not KO mice. Acute pressure overload, however, induced expressions of immediate-early response genes and activations of mitogen-activated protein kinases in the hearts of KO mice as well as WT mice. Both basal and activated levels of all these responses were significantly higher in KO mice than in WT mice. Pressure overload markedly increased the heart weight-to-body weight ratio in both mice strains at 14 days after aortic banding. These results suggest that acute hypertrophic responses could be induced by pressure overload in the in vivo heart without AT1 signaling.


Subject(s)
Angiotensin II/metabolism , Cardiomegaly/physiopathology , Ventricular Pressure/physiology , Angiotensin II/pharmacology , Animals , Aorta , Calcium-Calmodulin-Dependent Protein Kinases/analysis , Cardiomegaly/metabolism , Gene Expression/drug effects , Genes, fos , Genes, jun , Hemodynamics/physiology , Infusions, Intravenous , Mice , Mice, Knockout , Natriuretic Peptide, Brain , Nerve Tissue Proteins/genetics , Polymerase Chain Reaction/methods , Transcription, Genetic
17.
Circulation ; 96(11): 3954-62, 1997 Dec 02.
Article in English | MEDLINE | ID: mdl-9403620

ABSTRACT

BACKGROUND: Angiotensin (Ang) II type 1 receptor (AT1-R) induces cardiomyocyte hypertrophy and fibroblast proliferation, whereas the physiological role of AT2-R in cardiac remodeling remains poorly defined. METHODS AND RESULTS: Using Bio14.6 cardiomyopathic (CM) hamsters, we found that AT2-R sites were increased by 153% during heart failure compared with F1B controls. AT1-R numbers were increased by 72% in the hypertrophy stage and then decreased to the control level during heart failure. Such differential regulation of AT2-R and AT1-R during heart failure was consistent with changes in the respective mRNA levels. Autoradiography and immunocytochemistry revealed that both AT2-R and AT1-R are localized at higher densities in fibroblasts present in fibrous regions. Surrounding myocardium predominantly expressed AT1-R, but the level of expression was less than that in fibrous regions. Cardiac fibroblasts isolated from CM hearts during heart failure but not from control hamsters expressed AT2-R (30 fmol/mg protein). Using the cardiac fibroblasts expressing AT2-R, we found that Ang II stimulated net collagenous protein production by 48% and pretreatment with an AT2-R antagonist, PD123319, evoked a further elevation (83%). Ang II-induced synthesis of fibronectin and collagen type I were enhanced by 40% and 53%, respectively, by pretreatment with PD123319. Ang II-induced DNA synthesis (assessed by [3H]thymidine uptake) was significantly increased by PD123319, and the AT2-R agonist CGP42112A reduced the serum-stimulated increase in cell numbers by 23%. Treatment with an AT1-R antagonist, TCV116, for 20 weeks inhibited progression of interstitial fibrosis by 28%, whereas with 44-week PD123319 treatment but not 20-week treatment, the extent of the fibrous region was increased significantly, by 29%. CONCLUSIONS: These findings demonstrate that AT2-R is re-expressed by cardiac fibroblasts present in fibrous regions in failing CM hearts and that the increased AT2-R exerts an anti-AT1-R action on the progression of interstitial fibrosis during cardiac remodeling by inhibiting both fibrillar collagen metabolism and growth of cardiac fibroblasts.


Subject(s)
Cardiomyopathy, Dilated/metabolism , Collagen/metabolism , Fibroblasts/metabolism , Gene Expression Regulation , Myocardium/metabolism , Myofibrils/metabolism , Receptors, Angiotensin/biosynthesis , Angiotensin Receptor Antagonists , Animals , Autoradiography , Cardiomyopathy, Dilated/drug therapy , Cardiomyopathy, Dilated/pathology , Cell Division , Cricetinae , DNA Probes , Fibroblasts/drug effects , Fibrosis , Gene Expression Regulation/drug effects , Immunohistochemistry , Myocardium/cytology , Organ Size , Precipitin Tests , RNA, Messenger/analysis , Receptors, Angiotensin/genetics
18.
Hypertens Res ; 19(4): 271-9, 1996 Dec.
Article in English | MEDLINE | ID: mdl-8986458

ABSTRACT

The rat angiotensin II type 2 receptor (AT2-R) gene was isolated, and cis-regulatory regions in its 5'-flanking area were analyzed. Primer extension and RNase protection analyses revealed a single transcriptional initiation site at the position 24 bp downstream of the TATA box. The 5'-flanking region of AT2-R contained several cis-regulatory elements, such as AP-1, AP-2, C/EBP, NF-1, NF-IL6, NF-kappa B, and glucocorticoid- and cAMP-responsive elements (CRE). The treatment of PC12 cells with dibutyryl cAMP caused a marked decrease (90%) in the AT2-R mRNA level, which was blocked by the inhibitor of protein kinase A and did not require new protein synthesis. The protein level was also reduced 84% after a 24-h exposure to cAMP and the binding affinity was unchanged. The half-life of the AT2-R mRNA decreased -66% by cAMP as compared with control (18.4 +/- 0.4 h). Deletion and mutation analyses of the 5'-flanking region (1.2 Kb) revealed that there were one negative (-1,199 to -739) and two positive cis-regulatory regions (-739 to -436 and -59 to +45), and that the CRE motif located at -426 repressed (-23%) the promoter activity of the rat AT2-R gene. The region between -59 and +45 containing TATA box and AP-2 site accounted for 70% of the promoter activity. These findings indicate that the promoter activity of the rat AT2-R gene is modulated by several cis-regulatory regions and that cAMP markedly downregulates the expression of the AT2-R mainly by inducing AT2-R mRNA destabilization rather than CRE-mediated inhibition of the gene transcription. Thus, humoral factors that transduce cAMP as an intracellular signal may modulate AT2-R-mediated function of Ang II by reducing AT2-R expression.


Subject(s)
Cyclic AMP/pharmacology , Down-Regulation/drug effects , Promoter Regions, Genetic/genetics , Receptors, Angiotensin/genetics , Animals , Base Sequence , Blotting, Northern , Bucladesine/pharmacology , Cloning, Molecular , Dactinomycin/pharmacology , Gene Expression Regulation/drug effects , Genes, Reporter , Genetic Complementation Test , Luciferases , Molecular Sequence Data , PC12 Cells/drug effects , PC12 Cells/physiology , Protein Synthesis Inhibitors/pharmacology , RNA, Messenger/metabolism , Rats , Receptor, Angiotensin, Type 2 , Receptors, Angiotensin/metabolism , Sequence Analysis, DNA , Transcription, Genetic/drug effects , Transcription, Genetic/genetics
19.
Hypertension ; 28(5): 810-7, 1996 Nov.
Article in English | MEDLINE | ID: mdl-8901828

ABSTRACT

The cDNA sequence of rat angiotensin II type 1A receptor (AT1AR) shows that AT1AR transcripts have AUG triplets in the 5'-leader region that may begin a short open reading frame encoding an 11-amino acid peptide. In this study, the mutational inactivation of the start codon of the short open reading frame in AT1AR-chloramphenicol acetyltransferase (CAT) reporter gene constructs resulted in a 2.6-fold increase in CAT activity, whereas CAT transcript levels were not affected. Furthermore, experiments with rat AT1AR cDNA-transfected Cos-7 cells revealed that mutagenesis of the upstream AUG increased the AT1AR protein up to 2.5-fold, although AT1AR transcript levels showed no changes. The synthetic peptide corresponding to the sequence of the short open reading frame significantly suppressed the amount of AT1AR product in the in vitro translation system. The inhibiting effect of the short open reading frame appears to operate at least in part at the level of translation initiation, because polysome analysis with transfected Cos-7 cells showed that mutagenesis of the upstream AUG resulted in a shift of AT1AR mRNA distribution from a smaller to larger fraction of polysomes. Taken together, these results show that the upstream AUG inhibits translational regulation, suggesting that the short open reading frame in the 5'-leader region of AT1AR transcripts has a certain role in the translation of AT1AR protein.


Subject(s)
Chloramphenicol O-Acetyltransferase/pharmacology , Receptors, Angiotensin/genetics , Animals , Base Sequence , Cells, Cultured , Frameshifting, Ribosomal , Molecular Biology , Molecular Sequence Data , Muscle, Smooth, Vascular , Mutagenesis , Rats , Rats, Wistar , Sequence Analysis, DNA , Transfection
20.
Circ Res ; 79(4): 887-97, 1996 Oct.
Article in English | MEDLINE | ID: mdl-8831515

ABSTRACT

Mechanical stress plays a pivotal role in the development of cardiac hypertrophy during hemodynamic overload, and angiotensin (Ang) II secreted from stretched myocytes plays an important role in mechanical stretch-induced hypertrophy. In the present study, we examined stretch-induced expression of Ang II receptors in an in vitro stretch model using 1-day-old rat myocytes. Both Ang II type 1 receptor (AT1-R) and type 2 receptor (AT2-R) mRNA levels were upregulated by myocyte stretching with similar time courses: significant increases were evident 6 hours after stretching, maximal levels (2.8- and 3.3-fold, respectively) were observed at 12 hours, and these were sustained for up to 18 hours. Ang II receptor expression in fibroblast-rich cultures was not affected by stretching. Conditioned medium in which myocytes were stretched for 12 hours significantly downregulated AT1-R and AT2-R mRNA levels in recipient myocytes, and this effect was almost completely blocked by AT1-R antagonists but not AT2-R antagonists. Stretch-induced expression of AT1-R and AT2-R mRNAs was further increased by 27% and 31%, respectively, after pretreatment with AT1-R antagonists, suggesting that Ang II secreted from stretched myocytes downregulates both AT1-R and AT2-R. Western blot and binding assays showed that the number of AT1-Rs and AT2-Rs increased by 2.4- and 2.6-fold, respectively, without affecting receptor affinities. Inositol phosphate response to 0.5 mumol/L Ang II was enhanced 2.1-fold in stretched myocytes. Nuclear runoff assays and treatment with actinomycin D revealed that stretch-induced upregulation of AT1-R was mainly due to increased transcription, whereas that of AT2-R resulted from a stabilizing effect on AT2-R mRNA metabolism. Stretch-induced changes in levels of Ang II receptors were inhibited by genistein but not by H-7, staurosporin, and protein kinase C depletion or by BAPTA-AM. Exposure to cycloheximide did not affect stretch-induced changes. These findings indicate that nonsecretory pathways activated by myocyte stretching upregulate the expression of Ang II receptor subtypes transcriptionally and posttranscriptionally through mechanisms involving stretch-activated tyrosine kinases independently of de novo protein synthesis and that the AT1-R-mediated action of Ang II is functionally enhanced in stretched cardiac myocytes.


Subject(s)
Myocardium/metabolism , Receptors, Angiotensin/biosynthesis , Angiotensin II/metabolism , Animals , Cells, Cultured , RNA, Messenger/biosynthesis , Rats , Stress, Mechanical
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