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Biomedical subjects

A Wada

Publications and source records attributed to A Wada.

At least 271 records · Page 15Linked to original sources
PubMed1994

Cardiorenal and neurohumoral effects of endogenous atrial natriuretic peptide in dogs with severe congestive heart failure using a specific antagonist for guanylate cyclase-coupled receptors.

BACKGROUND: To elucidate the extent of the compensatory role of endogenous atrial natriuretic peptide (ANP) in severe congestive heart failure (CHF), we examined the changes in hemodynamics and neuroendocrine and renal functions after incremental administration of an ANP antagonist, HS-142-1 (HS), in dogs with CHF. METHODS AND RESULTS: We assessed the effects of HS on the suppression of plasma and urinary cGMP levels as a marker of endogenous ANP activity in dogs without CHF. Bolus injections of 0.3 and 1.0 mg/kg HS reduced plasma cGMP levels to 77% and 60% and urinary cGMP excretion to 78% and 61% of the relevant control levels, respectively. Then the study was performed in dogs with CHF induced by chronic rapid ventricular pacing, and the plasma ANP level was sixfold higher than that in the controls. Hemodynamic, hormonal, and renal variables were determined both before and after subsequent incremental administration (0.3, 1.0, and 3.0 mg/kg every 30 minutes) of HS. HS lowered the plasma and urinary cGMP levels dose dependently to 32% and 37% of the control levels, respectively. Mean arterial, pulmonary capillary wedge, and right atrial pressures and cardiac output did not change significantly. However, plasma renin activity, aldosterone level, and norepinephrine level increased rapidly to 226%, 179%, and 252% of the control values, respectively. Urine flow rate and urinary sodium excretion were significantly inhibited, with no concomitant change in glomerular filtration rate or renal plasma flow. CONCLUSIONS: These findings suggest that endogenous ANP contributes to the suppression of the activation of the renin-aldosterone system and sympathetic nervous activity and body fluid retention but that the vasodilative action of this peptide is attenuated in advanced CHF.

Animals↗
PubMed1994

Plasma arteriovenous cGMP difference as a useful indicator of nitrate tolerance in patients with heart failure.

BACKGROUND: The present study was performed to evaluate the effects of nitroglycerin (GTN) on plasma arteriovenous cGMP production and to compare its hemodynamic effects in patients with congestive heart failure (CHF). We also estimated the potential clinical value of plasma arteriovenous cGMP production as an indicator of nitrate tolerance. METHODS AND RESULTS: Plasma arterial and venous cGMP levels, atrial natriuretic peptide level, and hemodynamic parameters were measured before and after GTN infusion in 14 patients with CHF. Although the plasma levels of arterial cGMP and atrial natriuretic peptide decreased immediately after GTN, the plasma level of venous cGMP did not change. GTN infusion caused a dose-dependent increase in plasma arteriovenous cGMP production, and there was a positive correlation between the decrease of pulmonary capillary wedge pressure and the increase of plasma arteriovenous cGMP production immediately after GTN. Hemodynamic tolerance was observed after both 12 and 24 hours, when plasma arteriovenous GMP production was also attenuated. CONCLUSIONS: These findings indicate that the plasma arteriovenous cGMP difference is a clinical indicator of vasodilatory action of GTN and a useful indicator of nitrate tolerance in patients with CHF.

Atrial Natriuretic Factor↗
PubMed1994

Structure-activity study of chicken calcitonin gene-related peptide (CGRP) on vasorelaxation in rat mesenteric resistance vessels.

Structure-activity relationship of the chicken calcitonin gene-related peptide (cCGRP) was investigated and compared with human-alpha-CGRP (hCGRP) and rat CGRP (rCGRP) in the perfused mesenteric vascular beds of rats. In precontracted mesenteric vascular beds, cCGRP, hCGRP and rCGRP produced a concentration-dependent vasodilation. The vasodilator activities of cCGRP and rCGRP were equipotent and more potent than that of hCGRP. (Ala2,7)cCGRP and (Des-1-Ala)-alpha-deamino cCGRP were 100- and 10-fold less potent than cCGRP, respectively. However, cCGRP[1-36] reduced vasodilator activity. The cCGRP[8-37] produced a vasoconstriction. Both cCGRP[8-37] and hCGRP[8-37] caused parallel shifts of the concentration-response curves of rCGRP to the right, but both peptides did not affect the maximum response and vasodilator responses to isoproterenol, these peptides being equipotent antagonists (pA2 values: 7.6 and 7.4). In rat brain membrane preparations, cCGRP and its fragments and analogues, except for cCGRP[1-36], competed for specific binding sites with [125I]-hCGRP. These results suggest that cCGRP has a potent vasodilator activity for which the disulfide bridge at position 2 and 7 of cCGRP is an important site and that position 37 is necessary for the binding of the peptide to the receptor. Also, cCGRP[8-37] is a competitive CGRP-receptor antagonist.

Amino Acid Sequence↗
PubMed1994

Pharmacological characterization of presynaptic calcitonin gene-related peptide (CGRP) receptors on CGRP-containing vasodilator nerves in rat mesenteric resistance vessels.

Rat mesenteric arteries are innervated by calcitonin gene-related peptide (CGRP)-containing vasodilator nerves (CGRP nerves). This study investigated the presence of presynaptic CGRP receptors on CGRP nerves and the receptors' role in the regulation of CGRP release from these nerves. The rat mesenteric vascular bed was perfused with Krebs' solution containing 7 microM methoxamine plus 5 microM guanethidine to produce active tone and block adrenergic neurotransmission. In this preparation, periarterial nerve stimulation (PNS;2 Hz) and bolus infusion of CGRP (50 pmol) caused a decrease in perfusion pressure caused by vasodilation. Vasodilator response to PNS was abolished by 0.3 microM tetrodotoxin and by 1 microM human CGRP[8-37] (CGRP[8-37]), a CGRP receptor antagonist, which also abolished the response to bolus infusion of CGRP. Perfusion of CGRP (0.03-0.5 nM) dose-dependently inhibited vasodilator response to PNS, whereas it did not affect the response to bolus infusion of CGRP. The inhibitory effect of CGRP (0.3 nM) was antagonized by CGRP[8-37] (3 and 10 nM). Lower concentrations of CGRP[8-37] (1-10 nM) potentiated the vasodilator response to PNS, but higher concentrations (100 nM-1 microM) inhibited the response. The vasodilator response to bolus infusion of CGRP was dose-dependently inhibited by CGRP[8-37]. Eel calcitonin (5 and 50 microM), forskolin (0.01 and 0.1 microM), 3-isobutyl-1-methylxanthine (0.3 and 1 microM) and cyclic 8-bromo-adenosine 3':5'-monophosphate (10 and 100 microM) had no effect on the PNS-induced vasodilation. These results suggest that CGRP nerves are endowed with presynaptic CGRP receptors, which regulate CGRP release from the nerves via a negative feedback mechanism.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Immunohistochemical survey of pS2 expression in intraductal lesions associated with invasive ductal carcinoma of the breast.

We examined the expression of pS2 protein in 48 invasive ductal breast carcinomas with an extensive intraductal component, using immunohistochemical staining of paraffin-embedded sections. The patients selected for this study would have met the criteria for breast-conserving surgery applied at our institute at present. The rate of pS2 expression in the intraductal lesion was significantly higher than that in the main invasive lesion. The incidence of pS2 protein expression in the latter lesions was very similar to that in invasive carcinoma without intraductal lesions. The pS2 positivity of the intraductal lesion was equal to or higher than that of the invasive lesion. Of intraductal lesions, those classified as non-comedo carcinomas frequently contained more pS2 protein than did comedo carcinomas.

Breast Neoplasms↗
PubMed1993

Vasodilator effect of adrenomedullin and calcitonin gene-related peptide receptors in rat mesenteric vascular beds.

The effect of adrenomedullin, a novel peptide of 52 amino acids, on vascular tone was investigated in the perfused rat mesenteric vascular bed. In the vasculature contracted with methoxamine, perfusion of adrenomedullin (10(-11)-10(-7) M) caused a concentration-dependent decrease in perfusion pressure due to vasodilation. Additionally, a bolus infusion of adrenomedullin (300 and 500 pmol) produced a long-lasting vasodilator response, which was not affected in the presence of atropine (10(-7) M) and propranolol (10(-7) M). However, this response was inhibited in the presence of CGRP [8-37] (10(-6) M), an antagonist for CGRP receptor. These results suggest that adrenomedullin induces nonadrenergic and noncholinergic vasodilation in which CGRP receptors may be involved.

Adrenomedullin↗
PubMed1993

Pressor response to microinjection of clonidine into the hypothalamic paraventricular nucleus in conscious rats.

We have reported that intracerebroventricular (i.c.v.) injection of clonidine causes pressor response in conscious rats. To determine the effective brain site, cardiovascular responses induced by unilateral microinjection of clonidine into various hypothalamic nuclei of conscious rats were studied. Microinjection of clonidine (5-20 micrograms/0.5 microliter) into the paraventricular nucleus (PVN) of conscious rats dose-dependently produced a long-lasting pressor response with a decrease in heart rate, which mimicked the response to i.c.v. injection of clonidine. However, clonidine (10 micrograms) injection into various hypothalamic nuclei (anterior, posterior, ventromedial and dorsomedial nucleus) caused a small or no pressor response. In anesthetized rats, clonidine injected into the PVN induced a long-lasting depressor response concomitant with bradycardia. PVN pretreatment with the alpha 2-adrenoceptor antagonist, yohimbine (1 and 10 micrograms), dose-dependently inhibited the pressor response to PVN injected clonidine, but the alpha 1-adrenoceptor antagonist, prazosin (1 microgram), had no significant effect. Central (i.c.v.) pretreatment with the vasopressin (AVP) V1-receptor antagonist, [d(CH2)5Tyr(Me)]-AVP (0.5 and 2.0 micrograms), dose-dependently inhibited the pressor response to PVN injection of clonidine (10 micrograms), while systemic (i.v.) and local (intra-PVN injection) pretreatments with V1-receptor antagonist (2.0 micrograms) had no effect. These results suggest that the pressor response to microinjection of clonidine into the PVN of conscious rats is mediated by endogenous brain AVP, which is released by activation of alpha 2-adrenoceptors. It is also suggested that the PVN is a possible brain site for the pressor response to i.c.v. injected clonidine.

Adrenergic alpha-Antagonists↗
PubMed1993

A 5 kDa protein (SCS23) from the 30 S subunit of the spinach chloroplast ribosome.

The proteins of the 30 S ribosomal subunits from spinach chloroplasts were investigated using a radical-free and highly reducing (RFHR) method of two-dimensional polyacrylamide gel electrophoresis (PAGE). Twenty-three proteins were resolved on the gel down to the smallest protein of 5 kDa. The N-terminal amino acid sequence of the 5 kDa protein showed no homology with that of any other protein stored in databases, and the copy numbers were estimated to be 0.88 +/- 0.16 and 0.72 +/- 0.04 in the 30 S subunits and the 70 S ribosomes, respectively. The results suggest that the 5 kDa protein, which we have called SCS23, may be an essential ribosomal protein specific to spinach chloroplasts.

Amino Acid Sequence↗
PubMed1993

Regulation of the Escherichia coli rmf gene encoding the ribosome modulation factor: growth phase- and growth rate-dependent control.

Ribosome modulation factor (RMF) is a protein specifically associated with 100S ribosome dimers which start to accumulate in Escherichia coli cells upon growth transition from exponential to stationary phase. The structural gene, rmf, encoding the 55 amino acid residues RMF protein has been cloned from the 21.8 min region of the E. coli genome and sequenced. While rmf was silent in rapidly growing exponential phase cells, a high level of transcription took place concomitantly with the growth transition to stationary phase. Under slow growth conditions, rmf was expressed even in exponential phase and there was an inverse relationship between the expression of rmf and the cell growth rate. Thus, the expression profile of rmf is contrary to those of genes for ribosomal components and ribosome-associated proteins constituting the translational apparatus. The katF gene product, a stationary phase-specific sigma factor, was not required for the expression of rmf. Disruption of rmf resulted in loss of ribosome dimers and reduction of cell viability during stationary phase.

Amino Acid Sequence↗
PubMed1993

Expression of a truncated guanylate cyclase (GC-C), a receptor for heat-stable enterotoxin of enterotoxigenic Escherichia coli, and its dimer formation in COS-7 cells.

A fragment of guanylate cyclase C (GC-C) of about 1.7 k bp corresponding to amino acids 1-553 spanning the extracellular and transmembrane domains and a portion of the intracellular region was amplified using template cDNA prepared from rat intestinal cells by the polymerase chain reaction method. The cloned 1.7 k bp fragment was inserted into the mammalian expression vector pCGUT and the truncated GC-C expressed on the surface of COS-7 cells was demonstrated to bind heat-stable enterotoxin by photo affinity labeling with 125I-N-5-azidonitrobenzoyl-STh[5-19]. Analysis by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis showed that the truncated GC-C formed dimers on the surface of COS-7 cells. The intracellular region of GC-C was found not to be necessary for dimer formation by the GC-C. Comparison of the molecular weights of the truncated GC-C expressed in COS-7 cells and Escherichia coli suggested that the truncated GC-C was glycosylated in the mammalian expression system.

Affinity Labels↗
PubMed1993

N omega-nitro-L-arginine, an inhibitor of nitric oxide synthesis, decreases noradrenaline outflow in rat isolated perfused mesenteric vasculature.

In the isolated perfused rat mesenteric vasculature with intestine attached N omega-nitro-L-arginine (L-NNA) (30 mumol/l), an inhibitor of nitric oxide (NO) synthesis from L-arginine, did not alter spontaneous noradrenaline outflow. Transmural field stimulation (2-10 Hz) caused a frequency-dependent increase in noradrenaline outflow. The evoked overflow was reduced by L-NNA. L-Arginine (0.3 mmol/l) attenuated the inhibition of noradrenaline overflow by L-NNA. These results suggest that NO increases the release of noradrenaline in rat mesenteric vasculature.

Animals↗
PubMed1993

Secondary structural changes of large and small fragments of bovine serum albumin in thermal denaturation and in sodium dodecyl sulfate denaturation.

The helicities in various fragments of bovine serum albumin (BSA) were examined in the thermal denaturation and in sodium dodecyl sulfate (SDS) denaturation. The thermal denaturation was examined in a temperature range between 2 and 65 degrees C. The helicity decreased with a rise of temperature and it recovered to some degree upon cooling temperature. A rather high reversibility was observed in the BSA fragments, which were located in the N-terminal of the parent protein and then contained the first large loop with no disulfide bridge. The high reversibility was available also for the helicity in the first large loop of the fragment, disulfide bridges of which were reduced. The fragments, which were smaller than one domain, became unstable in the SDS denaturation. The helicities of such fragments decreased in lower SDS concentrations compared with those of the intact BSA and the large fragments, which contained one or more domains. A resistance to the SDS denaturation appeared in the helices of every large loop even after the fragmentation. On the other hand, helicities of the fragments decreased to 20-25% upon the reduction of disulfide bridges. However, the helicities of these fragments increased to 35-40% in the SDS denaturation.

Animals↗
PubMed1993

The conformational analysis and photoisomerization of retinochrome analogs with polyenals.

3,7-Dimethyl-2,4,6,8,10-dodecapentaenal was synthesized for reconstitution of the retinochrome analog. Its opsin shift was 1000 cm-1 smaller than that of native retinochrome, whose chromophore contains the same number of double bonds. The conformational change from 6-s-trans to 6-s-cis, as figured in a retinal molecule, plays an important role in the formation of the retinochrome analog, based on the estimation of opsin shifts for retinal analogs locked in the 6-s conformation. Thus the conformation of the 6-7 single bond in the native retinochrome was suggested to be 6-s-cis. Analysis of the circular dichroic spectra of retinochrome analogs revealed that the 6-s conformation is independent of the appearance of the beta-band. The stereoselectivity in the photoisomerization of the retinal analogs by a retinochrome template depends on the hydrophobic binding in the region of the beta-ionone ring.

Circular Dichroism↗
PubMed1993

Molecular cloning and mapping of 16S-23S rRNA gene complexes of Staphylococcus aureus.

Staphylococcus aureus BB255, a derivative of NCTC8325, had six rRNA operons, and each operon contained two SmaI sites about 3 kb apart. By molecular cloning and pulsed-field gel electrophoresis, all operons were mapped at the junctions of SmaI fragments in the published map of NCTC8325 except one, which was connected to a previously unidentified 23-kb SmaI fragment.

Base Sequence↗
PubMed1993

Cardiac myxoma metastasized to the brain: potential role of endogenous interleukin-6.

Metastasis of a cardiac myxoma to the brain is extremely rare. We present the case of a 70-year-old man who had an atrial myxoma and two metastatic myxomas in the brain. The intracranial lesions were in fact diagnosed before the cardiac myxoma, since the patient developed hemiparesis before his cardiac symptoms occurred. Computerized tomography of the brain showed two high-density lesions, the larger of which was removed surgically. Follow-up computerized tomography revealed a progressive enlargement of the second lesion which was then resected. Histopathological examination showed all lesions to the benign myxomas. Interestingly, high concentrations of interleukin-6 were present in the patient's serum and cardiac myxoma. Interleukin-6 may possibly potentiate metastasis of cardiac myxoma.

Aged↗
PubMed1993

Direct expression of adrenodoxin reductase in Escherichia coli and the functional characterization.

A plasmid for direct expression in Escherichia coli of the mature form bovine adrenodoxin reductase was constructed from the full-size cDNA for the enzyme [Y. Sagara, Y. Takata, T. Miyata, T. Hara, and T. Horiuchi, J. Biochem. (Tokyo), 102, 1333 (1987)] and an expression vector pCWori+. The recombinant adrenodoxin reductase was purified from the transformed E. coli cell lysates using adrenodoxin-Sepharose affinity chromatography [T. Sugiyama and T. Yamano, FEBS Lett., 52, 145 (1975)] with a yield of 2.5 mg/l of culture. The purified recombinant enzyme showed a single band on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and migration was identical with that of the authentic enzyme purified from bovine adrenal cortex mitochondria. The recombinant enzyme had Ser at its amino-terminus and the sequence of the amino terminal 9 residues was identical with that of the authentic bovine enzyme. The absorption spectrum of the recombinant enzyme showed peaks at 270, 376, and 450 nm and shoulders at 425 and 475 nm. Flavin content of the recombinant enzyme was 0.8 mol FAD/mol. The apparent Km value for bovine adrenodoxin in NADPH-cytochrome c reductase activity using a reconstitution system was 16 nM, a value comparable with that of the authentic bovine enzyme (17 nM). The cholesterol side chain cleavage activity with a reconstitution system was about 75% of that obtained when the authentic enzyme was used.

Adrenal Cortex↗
PubMed1993

Highly purified eicosapentaenoic acid attenuates tissue damage in experimental myocardial infarction.

We examined the effects of dietary supplementation with eicosapentaenoic acid (EPA) on experimental myocardial infarction in dogs. Twenty-five dogs were fed standard diets, 10 of which were supplemented with EPA-ester (100 mg/kg body weight/day) for 8 weeks, while 15 served as controls. After ingesting EPA for 8 weeks, the ratio of EPA to arachidonic acid (AA) in platelet cell membranes significantly increased (from 0.033 to 0.105; p < 0.01). The chemotactic response of neutrophils to leukotriene B4 (LTB4) was reduced in the EPA group (34% reduction at 10(-6) M LTB4, p < 0.01). Also in the EPA group, the amount of 12-hydroxyeicosatetraenoic acid, one of the chemotactic products of AA in infarcted myocardium, was reduced to 40% (p < 0.05). EPA treatment resulted in significant reduction in the ultimate size of the infarcted area. Contractile function of infarcted myocardium was well-preserved in the EPA group. Myeloperoxidase activity, an indication of the infiltration of neutrophils into the infarcted myocardium, was less in the EPA group than in the controls (0.68 +/- 0.25 U/0.1 gr. vs 1.22 +/- 0.55 U/0.1 gr., p < 0.05). Therefore, we conclude that dietary supplementation with EPA attenuates ischemic myocardial damage through inhibition of neutrophilic infiltration into the infarcted myocardium.

Animals↗