Biomedical subjects

I Yamaguchi

Publications and source records attributed to I Yamaguchi.

At least 37 records · Page 2Linked to original sources

PubMed2001

Physiological and pathological cardiac hypertrophy induce different molecular phenotypes in the rat.

Pressure overload, such as hypertension, to the heart causes pathological cardiac hypertrophy, whereas chronic exercise causes physiological cardiac hypertrophy, which is defined as athletic heart. There are differences in cardiac properties between these two types of hypertrophy. We investigated whether mRNA expression of various cardiovascular regulating factors differs in rat hearts that are physiologically and pathologically hypertrophied, because we hypothesized that these two types of cardiac hypertrophy induce different molecular phenotypes. We used the spontaneously hypertensive rat (SHR group; 19 wk old) as a model of pathological hypertrophy and swim-trained rats (trained group; 19 wk old, swim training for 15 wk) as a model of physiological hypertrophy. We also used sedentary Wistar-Kyoto rats as the control group (19 wk old). Left ventricular mass index for body weight was significantly higher in SHR and trained groups than in the control group. Expression of brain natriuretic peptide, angiotensin-converting enzyme, and endothelin-1 mRNA in the heart was significantly higher in the SHR group than in control and trained groups. Expression of adrenomedullin mRNA in the heart was significantly lower in the trained group than in control and SHR groups. Expression of beta(1)-adrenergic receptor mRNA in the heart was significantly higher in SHR and trained groups than in the control group. Expression of beta(1)-adrenergic receptor kinase mRNA, which inhibits beta(1)-adrenergic receptor activity, in the heart was markedly higher in the SHR group than in control and trained groups. We demonstrated for the first time that the manner of mRNA expression of various cardiovascular regulating factors in the heart differs between physiological and pathological cardiac hypertrophy.

Actins↗

PubMed2001

Prednisolone inhibits an IgE-mediated late-phase allergic cutaneous reactionby interfering with the activation of mast cells in mice.

Epicutaneous antigen challenge in passively sensitized mice with IgE produces a biphasic cutaneous response which peaks 1 h (immediate-phase reaction) and 24 h (late-phase reaction; LPR) after the antigen challenge. In this model, anaphylactic degranulation and interleukin 6 (IL-6) expression between 4 and 8 h are observed in resident mast cells as the preceding stage of LPR. Prednisolone at a dose of 3 mg kg(-1) clearly inhibited the LPR when administered 2 h before and 4 h after antigen challenge. Slight or no inhibition of LPR was observed by prednisolone administered 6-12 h after challenge. Histologically, prednisolone treatment 2 h before antigen challenge completely inhibited edema and inflammatory cell infiltration, while treatment at 6 h did not at all. In order to investigate the relationship between inhibition of LPR by prednisolone and mast cell activation, the effects of prednisolone on degranulation of mast cells and IL-6 expression in mast cells were investigated. 8 h after antigen challenge, prednisolone clearly inhibited the increase in the number of anaphylactic degranulated and IL-6-positive mast cells by administration 2 h before challenge, but did not affect it by administration 6 h after challenge. These data indicate that the inhibitory mechanism of prednisolone on LPR, at least, involves the inhibition of mast cell activation before LPR.

Animals↗

PubMed2001

Torsade de pointes induced by intravenous and long-term oral amiodarone therapy in a patient with dilated cardiomyopathy.

A 70-year-old woman with dilated cardiomyopathy and ventricular tachyarrhythmia was initially treated in 1990 with intravenous amiodarone (240 mg). She developed a junctional escape rhythm (48 beats/min) with QT prolongation (QT: 0.68 s) and 8 h later developed torsade de pointes (TdP). Because other antiarrhythmic drugs did not suppress the arrhythmia, oral amiodarone (100 mg/day) was started in 1995, 7 weeks before she presented with congestive heart failure. The QT prolongation (QTc: 0.64) increased after administration of dopamine, and TdP again developed. This case suggests that amiodarone induces proarrhythmias by different mechanisms when administered intravenously or orally.

Administration, Oral↗

PubMed2001

Estimating pulmonary capillary wedge pressures using Doppler variables of early diastolic left ventricular inflow.

The present study was performed to determine whether a multilineal regression model based on the early diastolic transmitral flow peak velocity (E) and the propagation velocity of early diastolic inflow (PV) could estimate the pulmonary capillary wedge pressure (PCWP). PCWP and Doppler variables were simultaneously recorded in 30 patients. PCWP was estimated by multilinear regression analysis using E and PV. The predictive accuracy of the equation obtained from the analysis was tested prospectively in a separate group of 65 patients divided into 3 groups: left ventricular (LV) systolic dysfunction (Group A), LV hypertrophy (Group B), and preserved systolic function without hypertrophy (Group C). The initial results obtained in groups B and C, respectively, were: r=0.77; r=0.81. These results indicate that a multilinear regression model based on E and PV is a noninvasive method of accurately estimating PCWP in a variety of cardiac disease states.

Adult↗

PubMed2001

Using isoproterenol stress echocardiography to predict the response to carvedilol in patients with dilated cardiomyopathy.

Trials have demonstrated that carvedilol can produce hemodynamic, symptomatic, and prognostic improvements in dilated cardiomyopathy (DCM), but some DCM patients have deteriorated after carvedilol, developing congestive heart failure. The present study investigated the use of isoproterenol (ISP) stress echocardiography to select those patients with DCM who would respond to carvedilol. ISP was infused intravenously in 22 patients with DCM and they were classified into 2 groups based on the left ventricular systolic response: good response to ISP [change in fractional shortening (FS) with ISP > 0.05, n=13] and poor response to ISP (change < or = 0.05, n=9). In the good response group, FS significantly increased from 0.12+/-0.04 to 0.17+/-0.08 (mean+/-SD, p<0.05) with carvedilol, and 7 patients improved symptomatically (New York Heart Association class). However, in the poor response group, no significant difference was observed between FS at baseline and that at the end of follow-up. Moreover, only 1 patient in the poor response group improved symptomatically. ISP stress echocardiography can assist in selecting patients with DCM who will respond positively to carvedilol.

Adrenergic beta-Antagonists↗

PubMed2001

Conservative treatment of hemolytic complication following coil embolization in two adult cases of patent ductus arteriosus.

Two adult cases of relatively large patent ductus arteriosus (PDA) were treated by coil embolization, but were complicated by hemolysis that was successfully managed by medical treatment. Case 1 was a 67-year-old woman and Case 2 was a 71-year-old woman with a PDA of minimal diameter of 5.3 mm and 5.5 mm, respectively. The approach was via the pulmonary artery and 2 coils were delivered simultaneously into the ductus, known as the 'kissing coil technique'. Although immediately after the procedure only a small residual shunt was revealed by aortogram, hemolysis occurred for several hours after the procedure in both cases. A hemolytic complication usually needs additional coil embolization or surgical treatment, but in these 2 cases it was successfully treated by haptoglobin infusion to prevent nephropathy and by antiplasmin infusion to promote thrombus formation. Hemolytic complications of coil embolization of PDA can managed by medication when the residual shunt is minimal and the degree of hemolysis is mild.

Aged↗

PubMed2001

Efficient removal of sulfide following integration of multiple copies of the sulfide-quinone oxidoreductase gene (sqr) into the Escherichia coli chromosome.

For the oxidation and removal of hydrogen sulfide, which causes an offensive odor from the contents of animal intestines, recombinant strains of Escherichia coli were constructed. The sulfide-quinone oxidoreductase gene (sqr) from Rhodobacter capsulatus was integrated in low copy numbers into the chromosome of Escherichia coli W3110. Multiple copies of sqr on plasmids were also delivered into the cytoplasm of the same strain. The sqr genes were homologously transducted onto the chromosomal lacZ region and their existence there was verified by Southern blot analysis. Sulfide oxidation in a chemical medium effectively increased for the recombinant strains which carried 2 approximately 3 copies of sqr under the control of the lac or tac promoter in the chromosome, and also for strains which carried 10 copies of sqr under the control of the lac or tac promoter on plasmids. In both types of recombinant, the tac promoter was more effective for SQR expression than the lac promoter. Construction of a recombinant with 3 copies of sqr under the control of the tac promoter in the chromosome was unsuccessful. In recombinants with SQR activity lower than 700 nmol/mg cell protein/min, oxygen consumption increased proportionally to SQR activity. An elevation in SQR activity in this range resulted in an increase in oxygen consumption and a decrease in sulfide concentration. When the recombinant cells were cultured until the 160th generation, WL2, WL3 and WT2, which carried 2, 3 and 2 copies of sqr in the chromosome, respectively, retained SQR activity similar to that of the first generation. For WL300 and WT20 which carried multi-copies of sqr in plasmids SQR activity was undetectable. The recombinant with 2 copies of sqr in the chromosome regulated by the tac promoter was most suitable for sulfide oxidation and growth of the cells.

Journal Article↗

PubMed2001

Introduction of bacterial metabolism into higher plants by polycistronic transgene expression.

Multiple-gene transformation is required to improve or change plant metabolisms effectively; but this many-step procedure is time-consuming and costing. We succeeded in the metabolic engineering of tobacco plants by introducing multiple genes as a bacteria-type operon into a plastid genome. The tobacco plastid was transformed with a polycistron consisting of three bacterial genes for the biosynthesis of a biodegradable polyester, polyhydroxybutyrate (PHB). Accumulation of PHB in the leaves of the transgenic tobacco indicated that the introduced genes were polycistronically expressed. This "phyto-fermentation" system can be used in plant production of various chemical commodities and pharmaceuticals.

Acetyl-CoA C-Acyltransferase↗

PubMed2001

Characterization of PBZ1, a probenazole-inducible gene, in suspension-cultured rice cells.

Probenazole (PBZ) induces non-race specific resistance in rice plants against rice blast fungus and PBZ1 was identified as a PBZ-inducible gene from rice. The induction of PBZ1 expression in suspension-cultured rice cells was investigated. Northern blot analysis indicated that PBZ1 was induced by PBZ in a dose-dependent manner. Enzyme-linked immunosorbent assay (ELISA) showed a dose and time-dependent accumulation of PBZ1 protein. Both mRNA and protein analysis showed that PBZ1 was not induced by salicylic acid or an active metabolite, 1,2-benzisothiazole-1,1-dioxide.

Cell Line↗

PubMed2001

Expression pattern of the CsPK3 auxin-responsive protein kinase gene.

We have previously cloned a cDNA of a putative serine/threonine protein kinase gene named CsPK3 from cucumber, the mRNA level of which was up-regulated by auxin and down-regulated by light irradiation. To examine the CsPK3 gene expression in detail, we cloned a genomic DNA of CsPK3 gene and made transgenic tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) plants containing the fused CsPK3 promoter-beta-glucuronidase gene. The beta-glucuronidase expression was detected in the shoot apex, vascular tissues, and the outermost layer of cortex. The histological distribution of CsPK3 mRNA in cucumber seedlings was supported by in situ hybridization, where the positive signals were observed in similar tissues as those observed by beta-glucuronidase staining. The responsiveness of the CsPK3 gene to auxin and light was also confirmed for beta-glucuronidase activity. The pattern of beta-glucuronidase staining changed during the development of the tobacco seedlings. The results of our experiment showed that CsPK3 was expressed in a wide variety of tissues and cells in which the developmental and growth controls by auxin are suggested.

Cucumis sativus↗

PubMed2001

Extension of A beta2M amyloid fibrils with recombinant human beta2-microglobulin.

In order to elucidate the pathogenesis of A beta2M amyloidosis, we established an experimental system to study the mechanism of amyloid fibril formation or degradation in vitro. We compared the kinetics of A beta2M amyloid fibril (fA beta2M) extension with native beta2microglobulin (n-beta2M) purified from the urine of a patient suffering from renal insufficiency, with that with recombinant beta2M (r-beta2M) in vitro. n-Beta2M and r-beta2M were incubated with fA beta2M purified from synovial tissues excised from A beta2M amyloidosis patients. The fA beta2M extension reaction could be explained by a first-order kinetic model in both beta2Ms. The extension reaction was greatly dependent on the pH of the reaction mixture and maximum around pH 2.5-3.0 in both beta2Ms. The fA beta2M extended with both beta2Ms assumed the similar helical filament structure, although the fibrils extended with r-beta2M were slightly wider than those extended with n-beta2M and the former fibrils assumed a helical structure more clearly as compared to the latter. In order to obtain pure, unmodified fA beta2M, we next extended fA beta2M repeatedly by the algorithmic protocol with r-beta2M. As the generation of the extended fibrils proceeded, the initial rate of the extension reaction increased The ultrastructure of fibrils was completely preserved throughout the repeated extension steps. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting revealed that fA beta2M extended repeatedly with r-beta2M were composed solely of r-beta2M. The use of these r-beta2M and fA beta2M will be advantageous to assess the effects of several amyloid-associated molecules in the formation or degradation of fA beta2M in vitro.

Amyloid↗

PubMed2001

Impaired ability to secrete atrial natriuretic peptide in response to isoproterenol infusion in patients with dilated cardiomyopathy.

OBJECTIVES: The myocardium has 2 functions in vivo, that of pump and endocrine organ. Therefore, simultaneous examinations of cardiac systolic reserve and endocrine reserve are important in evaluating the activities of the myocardial cells. This study investigated the relationship between cardiac systolic reserve and secretion of atrial natriuretic peptide (ANP) in response to isoproterenol infusion in patients with dilated cardiomyopathy. METHODS: Isoproterenol was infused intravenously in 6 healthy individuals (control group) and 32 patients with dilated cardiomyopathy. The left ventricular systolic responses and plasma ANP concentrations were measured. RESULTS: Patients with dilated cardiomyopathy were classified into 2 groups: patients with a good response (change in fractional shortening > 7%, 17 patients) and those with a poor response (change in < or = 7%, 15 patients). There was no significant difference in end-diastolic dimension, fractional shortening, heart rate, or systolic blood pressure between the 2 groups of patients with dilated cardiomyopathy at rest. The resting plasma ANP concentration in the poor-response group (88.8 +/- 59.0 pg/ml) was significantly higher than that in the other 2 groups (good: 47.0 +/- 35.9 pg/ml, p < 0.05, control: 9.8 +/- 4.1 pg/ml, p < 0.01, respectively). The percentage change in ANP after isoproterenol infusion in the poor-response group (-7.1 +/- 16.7%) was significantly less than that in the other 2 groups (good: 12.6 +/- 27.3%, p < 0.05, control: 31.5 +/- 24.6%, p < 0.01, respectively). CONCLUSIONS: The resting plasma ANP concentration can be used to evaluate the cardiac systolic reserve in patients with dilated cardiomyopathy. Decreased myocardial systolic reserve is also associated with impaired ability to secrete ANP.

Adrenergic beta-Agonists↗

PubMed2001

[Calf flow reserve measured by venous-occlusion near-infrared spectroscopy: relationship to exercise tolerance].

OBJECTIVES: The correlations between calf flow reserve evaluated with venous-occlusion near-infrared spectroscopy, air plethysmography or skin laser Doppler flowmetry were investigated in patients with cardiovascular diseases. The relationships to exercise tolerance during upright bicycle exercise were also examined. METHODS: The calf flow reserve (blood flow after 5 min of arterial occlusion/basal blood flow) evaluated by the above three methods and peak oxygen uptake (peak VO2) on bicycle exercise were measured in 24 male patients (mean age 65.0 +/- 7.7 years, left ventricular ejection fraction 24-86%). RESULTS: There was a good correlation between flow reserve by near-infrared spectroscopy (8.0 +/- 3.8) and air plethysmography (7.9 +/- 3.1; r = 0.90). However, there was a weak correlation between flow reserve by near-infrared spectroscopy and skin laser Doppler flowmetry (3.4 +/- 1.7; r = 0.42). There was a good correlation between flow reserve by near-infrared spectroscopy and peak VO2 (r = 0.69), or flow reserve by air plethysmography and peak VO2 (r = 0.53). However, there was no significant correlation between flow reserve by skin laser Doppler flowmetry and peak VO2 (r = 0.18). CONCLUSIONS: Calf flow reserve evaluated by venous-occlusion near-infrared spectroscopy relates to the flow reserve in the muscle tissue and is minimally affected by the flow reserve in the skin. The flow reserve in the muscle tissue is related to exercise tolerance, but the flow reserve in the skin is not, in patients with cardiovascular diseases.

Aged↗

PubMed2000

Specific determination of urinary 6beta-hydroxycortisol and cortisol by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

The urinary 6beta-hydroxycortisol to cortisol ratio is believed to be a noninvasive index of cytochrome P450 3A activity. For precise assessment of the ratio in human urine, we have developed a reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry method. The selective method was accurate and reproducible with intra- and inter-day precision of variation coefficients of less than 8%. The 6beta-hydroxycortisol to cortisol ratio ranged from 3.0 to 12.4 in healthy Japanese 24-h urine. With the recent popularization of LC-MS, our LC-MS method will be advantageous to detect human in vivo CYP3A activity for clinical investigation and routine measurement in various laboratories.

Adult↗

PubMed2000

Recognition of chitooligosaccharides and their N-acetyl groups by putative subsites of chitin deacetylase from a deuteromycete, Colletotrichum lindemuthianum.

The reaction pattern of an extracellular chitin deacetylase from a Deuteromycete, Colletotrichum lindemuthianum ATCC 56676, was investigated by use of chitooligosaccharides [(GlcNAc)(n)(), n = 3-6] and partially N-deacetylated chitooligosaccharides as substrates. When 0.5% of (GlcNAc)(n)() was deacetylated, the corresponding monodeacetylated products were initially detected without any processivity, suggesting the involvement of a multiple-chain mechanism for the deacetylation reaction. The structural analysis of these first-step products indicated that the chitin deacetylase strongly recognizes a sequence of four N-acetyl-D-glucosamine (GlcNAc) residues of the substrate (the subsites for the four GlcNAc residues are defined as -2, -1, 0, and +1, respectively, from the nonreducing end to the reducing end), and the N-acetyl group in the GlcNAc residue positioned at subsite 0 is exclusively deacetylated. When substrates of a low concentration (100 microM) were deacetylated, the initial deacetylation rate for (GlcNAc)(4) was comparable to that of (GlcNAc)(5), while deacetylation of (GlcNAc)(3) could not be detected. Reaction rate analyses of partially N-deacetylated chitooligosaccharides suggested that subsite -2 strongly recognizes the N-acetyl group of the GlcNAc residue of the substrate, while the deacetylation rate was not affected when either subsite -1 or +1 was occupied with a D-glucosamine residue instead of GlcNAc residue. Thus, the reaction pattern of the chitin deacetylase is completely distinct from that of a Zygomycete, Mucor rouxii, which produces a chitin deacetylase for accumulation of chitosan in its cell wall.

Acetylation↗

PubMed2000

Synthesis and biological activity of 4'-methoxy derivatives of abscisic acid.

Replacing the 4'-carbonyl group of abscisic acid with a methoxy group does not affect the abscisic acid (ABA)-like activities of the product in barley aleurone protoplasts, although the reduction of ABA to 4'-hydroxyl derivatives significantly reduces the ABA-like activity of the products. This suggests that methoxy derivatives of abscisic acid might be used to produce probes for ABA binding proteins.

Abscisic Acid↗

PubMed2000

Long-term endothelin receptor antagonist administration improves alterations in expression of various cardiac genes in failing myocardium of rats with heart failure.

BACKGROUND: We reported that long-term (3-month) treatment with the endothelin (ET) type A (ET(A)) receptor antagonist BQ-123 markedly improved survival in rats with chronic heart failure (CHF). However, it is not known whether long-term treatment with an ET receptor antagonist improves alterations in the expression of cardiac genes in failing hearts. METHODS AND RESULTS: CHF rats and control sham-operated rats were treated with BQ-123, SB209670 (ET(A/B) dual receptor antagonist), or saline (vehicle) for 3 months. The survival of CHF rats was markedly higher in the BQ-123 or SB209670 treatment group than in the saline treatment group. The changes in the gene expression of classic molecular markers for failing hearts (mRNA levels of atrial natriuretic peptide and beta-myosin heavy chain) were greatly inhibited by BQ-123 or SB209670 treatment in CHF rats. Long-term BQ-123 treatment also normalized the alterations in the expression of functional molecular markers in failing hearts (eg, mRNA levels of ryanodine receptor, sarcoplasmic reticulum Ca(2+)-ATPase, angiotensin-converting enzyme, angiotensin II type 1 receptor, and prepro-ET-1). CONCLUSIONS: We demonstrated for the first time that long-term (3-month) treatment with an ET receptor antagonist improves the alterations in the expression of various cardiac genes of classic molecular markers (eg, mRNA in atrial natriuretic peptide and beta-myosin heavy chain) and of functional molecular markers (eg, mRNA levels of ryanodine receptor, sarcoplasmic reticulum Ca(2+)-ATPase, angiotensin-converting enzyme, angiotensin II type 1 receptor, and prepro-ET-1) in the failing hearts of CHF rats, suggesting that the great improvement of survival in CHF rats by an ET blocker is partly attributed to the prevention of molecular changes in failing hearts.

Animals↗

PubMed2000

Low-dose dobutamine radionuclide ventriculography for prediction of myocardial viability: quantitative analysis of regional left ventricular function.

BACKGROUND: It is important to distinguish viable myocardium from necrotic tissue in order to decide upon therapy in patients with ischemic heart disease. HYPOTHESIS: We verified the hypothesis that quantitative analysis of regional left ventricular function using low-dose dobutamine radionuclide ventriculography (RNV) can sensitively predict myocardial viability and compared its usefulness with thallium-201 (201Tl) single-photon emission computed tomography (201Tl-SPECT). METHODS: Radionuclide ventriculography at rest and during low-dose dobutamine infusion (5 micrograms/kg/min), 201Tl-SPECT, and coronary angiography were performed in 51 subjects with severe ischemia-related stenosis of coronary arteries and 3 subjects without coronary artery disease. 201Tl uptake was assessed as normal (control), low perfusion (LP), or defect. We compared the response of regional function to dobutamine with the regional 201Tl uptake. The accuracy of both methods for identifying viable myocardium was investigated in 17 patients who underwent successful coronary revascularization, with a resulting improvement in wall motion. RESULTS: The increase in regional ejection fraction (delta r-EF) in response to dobutamine was significantly greater in the control (12 +/- 6%) and LP (16 +/- 11%) regions than in the defect (5 +/- 10%) regions. The increase in one-third regional ejection fraction (delta r-1/3EF) was also significantly higher in the control (14 +/- 7%) and LP (10 +/- 8%) regions than in the defect regions (5 +/- 6%). We defined myocardial viability as a delta r-EF > 5% or a delta r-1/3EF > 2%. The sensitivity and specificity of the delta r-EF for identification of myocardial viability were 91.4 and 55.5%, respectively. The sensitivity and specificity of the delta r-1/3EF were 91.4 and 66.6%, respectively; the corresponding values for 201Tl SPECT were 74.2 and 77.8%. CONCLUSION: Low-dose dobutamine RNV with quantitative analysis of regional left ventricular function was more sensitive for identification of viable myocardium than 201Tl-SPECT.

Aged↗