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Biomedical subjects

A Wada

Publications and source records attributed to A Wada.

At least 19 recordsLinked to original sources
PubMed1995

Elevated calcium level induces calcium-dependent proteolysis of A-CAM (N-cadherin) in heart--analysis by detergent-treated model.

Calcium overload induces cardiac muscle cell dysfunction in cardiovascular diseases. We investigated the effects of elevated calcium level on adherens-junction-specific cell adhesion molecule (A-CAM). Incubation of Triton X-100-treated canine heart homogenate in the presence of Ca2+ reduced the content of A-CAM. Reduction in A-CAM requires milli-molar Ca2+ and was inhibited by protease inhibitors, leupeptin and calpeptin. Immunohistochemical observation revealed that m-calcium-activated neutral protease (m-CANP) was colocalized with A-CAM in intercalated disks. These data suggested that m-CANP proteolyzes A-CAM in response to calcium overload in cardiac muscle.

Animals↗
PubMed1995

Prognostic value of plasma soluble intercellular adhesion molecule-1 and endothelin-1 concentration in patients with chronic congestive heart failure.

We tested the hypothesis that plasma endothelin-1 (ET-1) and soluble intercellular adhesion molecule-1 (sICAM-1) in patients with congestive heart failure (CHF) are related to subsequent survival, and assessed whether the measurements of these substances provide additional prognostic information to that obtained from clinical and biochemical variables previously known to be associated with high mortality. Plasma levels of sICAM-1 and ET-1 were measured in 102 patients with CHF (left ventricular ejection fraction [LVEF] < 0.45), and patients were followed up for > 18 months. The plasma level of sICAM-1 increased with the severity of CHF (normal, 149 +/- 10 ng/ml, mild CHF [New York Heart Association functional class II], 207 +/- 9.4 ng/ml, severe CHF [functional class III or IV], 293 +/- 18 ng/ml). The plasma level of ET-1 also increased with the severity of CHF (normal, 1.5 +/- 0.2 pg/ml, mild CHF, 2.1 +/- 0.1 pg/ml, severe CHF, 4.0 +/- 0.4 pg/ml). Plasma levels of both sICAM-1 and ET-1 decreased after treatment in 14 patients, with improvements in symptoms (from functional class IV to II) during the follow-up period. There was a significant positive correlation between the plasma level of ET-1 and plasma sICAM-1 (r = 0.44, p < 0.001). A significant negative correlation was observed between LVEF and plasma ET-1 (r = -0.34, p < 0.001), and plasma sICAM-1 (r = -0.36, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Ribosome modulation factor: stationary growth phase-specific inhibitor of ribosome functions from Escherichia coli.

Ribosome modulation factor (RMF) is an Escherichia coli protein associated with 100S ribosome dimers, which are formed at stationary growth phase or in slowly growing cells. RMF either purified from stationary-phase ribosomes or synthesized by a chemical method was examined for its functions. By adding either natural or synthetic RMF to 70S ribosomes prepared from both exponentially growing and stationary phase cells, 100S ribosome dimers were generated in a concentration-dependent manner. Protein synthesis in vitro was inhibited concomittantly with the formation of 100S ribosomes. The binding of aminoacyl-tRNA to ribosomes was inhibited in parallel. Taken together we propose that RMF is a stationary phase-specific inhibitor of ribosome functions and 100S dimers are stored forms of ribosomes.

Amino Acid Sequence↗
PubMed1995

Group II phospholipase A2 activates mitogen-activated protein kinase in cultured rat mesangial cells.

Group II phospholipase A2 (PLA2) is a mediator of inflammation in various disease including glomerulonephritis. We recently found that urinary excretion of PLA2 was increased in patients with mesangial proliferative glomerulonephritis and that interleukin-1 (IL-1) enhanced platelet derived growth factor-stimulated mesangial cell proliferation through the action of group II PLA2 secreted in response to IL-1 stimuli. Here we report signal transducing mechanism through group II PLA2 in mesangial cells. Group II PLA2 (1-15 U/ml) rapidly activated mitogen-activated protein (MAP) kinase. IL-1 beta activated MAP kinase in two phases and the slow activation in the late phase, proceeding in parallel with increased group II PLA2 secretion elicited by IL-1 treatment, was inhibited by the specific antibody raised against group II PLA2. This suggests that the late phase activation of IL-1-induced MAP kinase was mediated, at least in part, by secreted group II PLA2.

Animals↗
PubMed1995

Remarkable activity enhancement of thermolysin mutants.

Most attempts to modify the properties of enzymes by amino acid substitution around the active sites have resulted in suppression of the biological activity, suggesting that the structure of natural enzymes should be almost optimized evolutionally to show the highest activity. In contrast, we found an interesting site of a well-known metalloendopeptidase, thermolysin (EC.3.4.24.4), where almost all the amino acid replacement causes a remarkable increase in the hydrolytic activity. Negative correlation between the activity and the thermal stability was observed. The flexibility around the substrate binding site is suggested to be a key to the correlation. Nature may have selected the amino acid at this site, which suppresses the flexibility of the molecule, to get the highest thermal stability at the expense of the activity.

Enzyme Activation↗
PubMed1995

Comparison of hemodynamic effects and plasma cyclic guanosine monophosphate of nicorandil and nitroglycerin in patients with congestive heart failure.

Hemodynamic tolerance has been observed within several hours of continuous infusion of nitroglycerin (NTG). We examined the hemodynamic parameters as well as femoral arterial and venous cyclic guanosine monophosphate (cGMP) concentrations during intravenous infusion of NTG or nicorandil, a nitrate and potassium channel opener, in patients with congestive heart failure. Doses of NTG or nicorandil were titrated to achieve a > or = 25% reduction in pulmonary capillary wedge pressure (PCWP) within 1 hour, and the infusion was maintained at a constant rate for 24 hours. The reduction in PCWP and mean arterial blood pressure was identical after a 1-hour infusion of either NTG or nicorandil. In the NTG group, PCWP and mean blood pressure were not significantly different from the baseline value at 12 hours, but in the nicorandil group PCWP and mean blood pressure remained significantly lower than the preinfusion value for 24 hours. The cGMP production with NTG (assessed by the difference between the plasma arterial and venous cGMP level) paralleled the changes in PCWP, suggesting that the plasma arteriovenous cGMP difference is a biochemical indicator of nitrate tolerance. Although the sustained decrease in PCWP was observed in the nicorandil group, cGMP production with nicorandil was also attenuated at 24 hours of continuous infusion. These findings suggest that the absence of the hemodynamic tolerance of nicorandil, a nitrate and potassium channel opener, is likely due to its action as a potassium channel opener, and not to its nitrate activity.

Adult↗
PubMed1995

Stability of alpha-helices in a molten globule state of cytochrome c by hydrogen-deuterium exchange and two-dimensional NMR spectroscopy.

To distinguish between intrinsically stable helices and those stabilized by the protein three-dimensional structure, we report the hydrogen-deuterium exchange (H2H) rates of 29 amide protons of ferricytochrome c in a molten globule state (at 35 degrees C, pH 2.0 with 0.5 M KCl), monitored by 2D-NMR. The results of the H2H-exchange experiments have been analyzed to calculate the protection factors. The helices were not uniformly stable and amide protons of residues belonging to the N and C-terminal helices had high protection factors. The protection factors of amide protons involved in the 50's helix were low, and could not be determined quantitatively. In the 60's helix we found two amide protons with protection factors comparable to those of the N and C-terminal helices. These results, compared with previously reported intrinsic helicities of peptide fragments, indicate that the relative helicities of isolated fragments are not directly reflected in the stability of the helices in the molten globule state, even though this state has no rigid tertiary structure. This suggests that loose interactions between helices are present in the molten globule state of cytochrome c, and that they are essential for keeping the helicity of the helical segments. The loose tertiary interactions discussed here differ from the usual tertiary interaction found in the native state in that the specific interdigitization between side-chains is absent.

Amino Acid Sequence↗
PubMed1995

In vivo transfection of genes for renin and angiotensinogen into the glomerular cells induced phenotypic change of the mesangial cells and glomerular sclerosis.

Locally activated renin angiotensin system plays an important role in the progression of the glomerular diseases. In order to understand the local effect of overexpressed angiotensin II in the glomerulus in situ, we introduced human genes for renin and angiotensinogen into the rat kidney by hemagglutinating virus of Japan-liposome procedure. Three days after transfection human renin was detected in the glomeruli by immunohistochemistry. Seven days after transfection, extracellular matrix was expanded in the glomeruli and alpha-smooth muscle actin was expressed in the mesangial cells. These results suggest that locally activated renin angiotensin system induces glomerular sclerosis and a phenotypic change in mesangial cells.

Actins↗
PubMed1995

Proadrenomedullin N-terminal 20 peptide (PAMP), an endogenous anticholinergic peptide: its exocytotic secretion and inhibition of catecholamine secretion in adrenal medulla.

In cultured bovine adrenal medullary cells, stimulation of nicotinic receptors by carbachol evoked the Ca(2+)-dependent exocytotic cosecretion of proadrenomedullin N-terminal 20 peptide (PAMP) (EC50 = 50.1 microM) and catecholamines (EC50 = 63.0 microM), with the molar ratio of PAMP/catecholamines secreted being equal to the ratio in the cells. Addition of PAMP [1-20]NH2 inhibited carbachol-induced 22Na+ influx via nicotinic receptors (IC50 = 2.5 microM in a noncompetitive manner and thereby reduced carbachol-induced 45Ca2+ influx via voltage-dependent Ca2+ channels (IC50 = 1.0 microM) and catecholamine secretion (IC50 = 1.6 microM). It did not alter high K(+)-induced 45Ca2+ influx via voltage-dependent Ca2+ channels or veratridine-induced 22Na+ influx via voltage-dependent Na+ channels. PAMP seems to be a novel antinicotinic peptide cosecreted with catecholamines by a Ca(2+)-dependent exocytosis in response to nicotinic receptor stimulation.

Adrenal Medulla↗
PubMed1995

Possible regulation of renin release by ANP in dogs with heart failure.

We investigated whether atrial natriuretic peptide (ANP) contributed to the regulation of renin release during the development of experimental heart failure in dogs. Significant increases of plasma ANP and plasma guanosine 3',5'-cyclic monophosphate (cGMP) levels were observed in dogs with mild heart failure induced by 6 days of rapid ventricular pacing. However, plasma renin activity (PRA) was not elevated, despite the significant decreases in renal plasma flow and mean arterial pressure. An inverse correlation between PRA and the ratio of plasma cGMP to ANP (rs = -0.59, P < 0.05) was found in dogs subjected to 9 days of rapid pacing. In dogs with advanced heart failure induced by 15-24 days of rapid pacing, the plasma cGMP level did not increase further, despite the progressive increase in plasma ANP with the resultant significant increase in PRA (P < 0.05). These findings suggest that attenuation of the inhibitory effect of ANP on renin release during the development of severe heart failure may be an important factor in the activation of the renin-angiotensin system.

Animals↗
PubMed1995

Calcitonin gene-related peptide mediates acetylcholine-induced endothelium-independent vasodilation in mesenteric resistance blood vessels of the rat.

The role of calcitonin gene-related peptide (CGRP)-containing vasodilator nerves in acetylcholine chloride (ACh)-induced vasodilation was studied in the perfused mesenteric vascular bed isolated from the rat. Bolus infusions of ACh at smaller doses (0.1 and 1 nmol) produced rapid and short-lived vasodilation. However, larger doses (10 and 100 nmol) of ACh caused a rapid and subsequent long-lasting vasodilator response in which the duration of vasodilation was prolonged in a concentration-dependent manner. Pretreatment with capsaicin (1 mumol/L for 20 minutes) significantly shortened the duration of vasodilator response to ACh but did not affect the initial rapid phase of ACh-induced vasodilation. Chemical removal of the vascular endothelium by perfusion with sodium deoxycholate (1.75 to 1.80 mg/mL) for 30 seconds and subsequent treatment with N omega-nitro-L-arginine (100 mumol/L) to inhibit nitric oxide synthesis abolished the initial rapid vasodilator action of ACh at any given concentration. However, in the same preparation, increasing concentrations (from 1 to 1000 nmol) of ACh produced only the long-lasting vasodilator responses in a concentration-dependent manner. This long-lasting vasodilator response to ACh infusion was abolished by capsaicin pretreatment (1 mumol/L), human CGRP[8-37] (CGRP receptor antagonist, 1 mumol/L), and atropine (muscarinic ACh receptor antagonist, 1, 10, and 100 nmol/L) but not by hexamethonium (nicotinic ACh receptor antagonist, 1 and 10 mumol/L). In the preparations without endothelium, the bolus infusion of ACh (300 nmol for 30 seconds) evoked a long-lasting vasodilation and release of CGRP-like immunoreactivities into the perfusate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1995

[Affinity of estrogen binding in the cultured spinal ligament cells: an in vitro study using cells from spinal ligament ossification patients].

This immunological study investigated the effects of estrogen as a potential causative factor for spinal ligament ossification (such as ossification of the posterior longitudinal ligament, OPLL; ossification of the yellow ligament, OYL; and ossification of the anterior longitudinal ligament, OALL). The serum total estrogen (estron + estradiol + estriol) level in the OPLL patients and controls was measured by radioimmunoassay. To determine any difference in the affinity of the estrogen, 3,17 beta-estradiol receptors of cultured spinal ligament cells obtained from OPLL patient were detected by receptor binding assay, and compared with cells from controls. Additionally, to evaluate the responses of cultured spinal ligament cells to stimulation by 3,17 beta-estradiol, examined the production of bone Gla protein (BGP) in medium, the rate of tritiated thymidine (3H-TdR) uptake, and change in affinity of transforming growth factor-beta 1 (TGF-beta 1) receptor on those cells with 3,17 beta-estradiol added (E2+ group), and compared the results with those when 3,17 beta-estradiol was not added (E2- group). The serum total estrogen level was significantly higher in OPLL patients than in controls, and the level increased with increasing extent of ligament ossification. Cultured cells obtained from OPLL patients had receptors with a higher affinity for 3,17 beta-estradiol than did cells from controls. Cells obtained from OPLL patients responded to the stimulation by 3,17 beta-estradiol, accelerated BGP production, and elevated the 3H-TdR uptake. However, cells from controls showed no change in the stimulation by 3,17 beta-estradiol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Prostate and prostatic carcinoma: comparison of gadolinium-enhanced MR images and histopathologic findings].

The purpose of this study was to determine the patterns of enhancement in normal prostate, and to compare them with the enhancement patterns and histopathologic findings in patients with prostatic carcinoma. Seventeen patients who had no urogenital disease and 27 who underwent radical prostatectomy or prostatic biopsy were included in this study. All patients were evaluated with T1-, T2-weighted and gadolinium-enhanced T1-weighted images. With gadolinium enhancement the inner gland showed more enhancement than the peripheral zone in the normal prostate. The carcinoma tissue was enhanced more than the peripheral zone in 13 patients, about the same as the peripheral zone in 11 patients, and less than the peripheral zone in three patients. The three patients whose cancer tissue demonstrated no enhancement had poorly differentiated adenocarcinoma of the solid type. In conclusion, gadolinium-enhanced T1-weighted imaging is not reliable for routine use in MR imaging of the prostate, but may be useful to evaluate histologic types in patients with prostatic carcinoma.

Adolescent↗
PubMed1994

Batchwise purification of specific tRNAs by a solid-phase DNA probe.

A simple and efficient method for purifying a specific tRNA in a single microcentrifuge tube was developed. Oligodeoxyribonucleotides (about 30 mer) with sequences complementary to the 3' side of target tRNAs were synthesized with an aminohexyl linker at the 5' end, immobilized on a silica gel at a high concentration, and used as a solid-phase probe. A mixture of tRNAs was added to a suspension of the solid-phase probe in 2.4 M tetraethylammonium chloride and incubated for 10-30 min. Only a target tRNA hybridized with the immobilized probe at appropriate temperatures and was eluted out by heating. The solid-phase probe showed a large hybridization capacity (up to 17 A260 units/g dry gel) and specific and quantitative recovery of the target tRNA. The intactness of recovered tRNAs was ascertained by both Donis-Keller sequencing and aminoacylation experiments. These features show the usefulness of the solid-phase probe method as a reliable tool for purifying tRNAs whose gene sequences are known.

Base Sequence↗