Biomedical subjects

F Yamauchi

Publications and source records attributed to F Yamauchi.

At least 19 recordsLinked to original sources

PubMed1998

Antioxidative Properties of Histidine-Containing Peptides Designed from Peptide Fragments Found in the Digests of a Soybean Protein.

The properties of 22 synthetic peptides containing histidine, which were designed on the basis of the antioxidative peptide (Leu-Leu-Pro-His-His) derived from proteolytic digests of a soybean protein, were examined with regard to their antioxidative activity against the peroxidation of linoleic acid and the scavenging effects on active oxygen and free radical species. The antioxidative activities of these peptides in an emulsion oxidation system using 2,2'-azobis(2-amidinopropane) dihydrochloride as a radical initiator correlated well within an aqueous system. Although the histidine-containing peptides had a quenching activity on singlet oxygen, they did not show antioxidative activity in an 2,2'-azobis(2,4-dimethylvaleronitrile)-induced oxidation system or scavenging effects on 1,1-diphenyl-2-picrylhydrazyl radical and superoxide. The metal-ion chelating activities and the hydrophobicities of these peptides showed no direct correlation with their antioxidative activities. Leu-Leu-Pro-His-His was modified with a hydroxyl radical in an aqueous ethanol system during the peroxidation of linoleic acid.

Journal Article↗

PubMed1997

Glomerular Fc alphaR expression and disease activity in IgA nephropathy.

In this study, we examined the receptors for the Fc portion of immunoglobulin A (IgA) (Fc alphaR) in the glomeruli as well as circulating polymorphonuclear leukocytes and monocytes at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) assay and at the protein level by an immunohistochemistry/flow cytometry technique using a specific anti-Fc alphaR monoclonal antibody (My 43). Glomeruli were isolated from biopsy specimens of renal tissues from IgA nephropathy (IgAN; 20 cases) and non-IgA mesangial proliferative glomerulonephritis (PGN; 13 cases) patients, and from normal renal tissue specimens obtained from kidneys removed because of malignancies (five cases) applying the microdissection method. There was a relative increase in Fc alphaR in the circulating phagocytes from IgAN patients compared with those from PGN and healthy controls. Fc alphaR expression was present in approximately 40% of glomeruli samples from IgAN patients at the message levels. Fc alphaR-positive specimens were also strongly positive for expression of tumor necrosis factor-alpha, interleukin-1, and interleukin-6 mRNA. Specimens from PGN patients and healthy controls did not show any detectable Fc alphaR message. Serum IgA levels and severity of hematuria were significantly higher in patients with positive Fc alphaR expression. A message for Fc alphaR was detected in the tissues that were more damaged histologically. Our data suggest that there is some in vivo induction of glomerular Fc alphaR expression, possibly mediated by a synergistic stimulus from IgA and inflammatory cytokines, and the expressed receptor is likely to be involved in the disease process of IgAN.

Antigens, CD↗

PubMed1997

Expression of thromboxane synthase in kidney tissues from patients with IgA nephropathy.

Thromboxane A2 (TXA2) is a potent vasoconstrictor which is known to be involved in the pathogenesis of experimental glomerulonephritis, although its exact pathogenic significance is not clear in human glomerulonephritis. We have investigated the expression of thromboxane synthase (TXS) in kidney tissues from patients with IgA nephropathy (IgAN), using RT-PCR and immunohistochemical methods. Biopsied renal tissues from thirty-four patients with IgAN (24 whole tissues and 10 isolated glomeruli) and normal renal tissues from 11 nephrectomized kidneys (control, eight whole tissues and three isolated glomeruli) were included in this study. TXS mRNA expression was observed in 10 out of 24 (42%) whole tissue specimens from IgAN, but no such message was disclosed in the control tissue. There was no detectable TXS mRNA expression in the isolated glomeruli either from IgAN patients or controls, although constant mRNA expressions for GAPDH and VPF/VEGF were observed. IgAN patients with positive TXS mRNA had significantly reduced GFR with elevated serum creatinine and serum beta 2-microglobulin levels. Immunostaining, using a monoclonal anti-TXS antibody, identified the localization of the TXS protein in the interstitial areas where monocyte/macrophage infiltration was abundant, as well as in the arterioles of the kidney tissues with advanced tissue damage. It was concluded that TXA2 produced by the interstitial infiltrating cells during the inflammatory process might be involved in the progression of IgA nephropathy.

Creatinine↗

PubMed1996

Ostrich (Struthio camelus) carboxypeptidase B: purification, kinetic properties and characterization of the pancreatic enzyme.

Carboxypeptidase B has been isolated from numerous mammalian and invertebrate species. In contrast, very little is known about carboxypeptidases of avian origin. To provide information for a comparative study, we have undertaken an investigation of the kinetic and physical properties of ostrich carboxypeptidase B. Carboxypeptidase B from the pancreas of the ostrich was purified by water extraction of acetone powder and aminobenzylsuccinic acid affinity and hydroxylapatite chromatography. The effects of pH and temperature on CPB activity were examined. K(i)-values for numerous inhibitors (PCI, ABSA, hipp-D-lys, epsilon-aminocaproic acid, D-arg and 3-phenylproprionic acid) and kinetic parameters (K(m), k(cat) and k(cat)/K(m)) for several substrates (hipp-arg, hipp-lys, FAAA, FAAL and hipp-AA) were determined. N-terminal sequencing and amino acid analysis were also performed. Purified ostrich carboxypeptidase B was assessed to be homogeneous by SDS-PAGE with a M(r) value of approx. 35,000. For ostrich carboxypeptidase B the K(m) values for the different substrates were of the same order as those reported for other species, whereas the k(cat) values were 8- to 21-fold lower than the reported values. FAAA and hipp-AA were the preferred substrates. PCI was the most effective inhibitor, with a K(i) in the nM region, and no inhibition was shown with 3-phenylpropionic acid. The N-terminal sequence showed a high degree of homology when aligned with CPB from other species. Amino acid analysis showed significantly lower levels of Asx and Cyh and higher levels of Trp and Leu when compared with other species. Ostrich carboxypeptidase B would appear to show many physical, chemical and kinetic properties similar to those of other known carboxypeptidases.

Amino Acid Sequence↗

PubMed1996

Superoxide dismutase activity in human glomerulonephritis.

Superoxide dismutase (SOD) in renal tissue biopsy specimens obtained from patients with immunoglobulin A nephropathy (13 cases) and non-immunoglobulin A mesangial proliferative glomerulonephritis (nine cases) was studied at the protein level by an enzyme-linked immunosorbent assay method and at the mRNA level by the reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Total SOD activity in the tissue supernatant was measured by applying an electron paramagnetic resonance/spin trapping method. Normal renal tissues obtained from kidneys removed for malignancies (six cases) were included as healthy controls. The copper and zinc form of SOD (Cu,Zn-SOD) activity at both the protein and mRNA levels was lower in the moderately or severely damaged tissues compared with that in the normal or mildly damaged tissues. On the other hand, manganese SOD (Mn-SOD) values at either the protein level or the mRNA level did not differ significantly between control and patient samples. In the histochemical study using a polyclonal rabbit anti-Cu,Zn-SOD antibody, the staining intensity for Cu,Zn-SOD antigen was lower in the areas with advanced histologic damage than in the intact tissues. A follow-up study showed that renal function deterioration was proportionately slower in patients whose SOD activity was within the range of healthy tissue levels at the time of biopsy. Our data suggest that a lower level of SOD activity, whether as a cause or a consequence of the disease process, might induce a decrease in the scavenger reaction of superoxide (O2-) thus causing the tissue to become more vulnerable to oxidative stress.

Adult↗

PubMed1996

Expression of inducible-NOS in human glomerulonephritis: the possible source is infiltrating monocytes/macrophages.

Nitric oxide (NO) is a biological mediator which is synthesized from L-arginine by a family of nitric oxide synthases (NOS). In this paper, we have studied the expression of the inducible NO synthase (iNOS) in the tissues of the human kidney at the mRNA level by RT-PCR assay and at the protein level by an immunohistochemistry technique using a specific anti-macrophage NOS monoclonal antibody. Biopsied renal tissues from patients with IgA nephropathy (IgAN; 28 cases) and with non-IgA mesangial proliferative glomerulonephritis (PGN;12 cases), and normal renal tissues obtained from kidneys removed for malignancies (11 cases) were included in this experiment. iNOS message was present in about 73% tissues from IgAN and PGN patients, which was supported by histochemical findings and the iNOS positive cells were predominantly in the tubulointerstitial areas where infiltration of monocytes/macrophages was abundant. The iNOS positive tissues were also strongly positive for CD14, INF-gamma and TNF-alpha mRNA expression. In our in vitro study, iNOS expression was found only in cytokines (INF-gamma and TNF-alpha) stimulated monocytes/macrophages but not in lymphocytes and neutrophils. Normal renal tissues did not show any iNOS expression either at the mRNA level or at the protein level in this study. Clinical and histological data showed that decreased renal function and tubulointerstitial damage were greater in the iNOS expressing patients. This study demonstrates that there is some in vivo induction for iNOS expression, likely to be mediated by cytokines, for local NO production that might be involved in the initiation and/or progression of mesangial proliferative glomerulonephritis.

Base Sequence↗

PubMed1995

Ostrich pepsinogens I and II: purification, activation and chemical and immunochemical characterization of the enzymes from the proventriculus.

Pepsins are a series of gastric proteases secreted as inactive precursors (pepsinogens) which are active at acidic pH. The aim of this study was to purify ostrich pepsin(ogen)s and to compare their biochemical and immunological characteristics with those of pepsin(ogen)s of mammalian and avian origin. Ostrich pepsinogens were purified by ammonium sulphate fractionation, Toyopearl Super Q-650S chromatography and rechromatography, and hydroxylapatite chromatography of a pH 8.0 mucosal extract. Pepsins were obtained through acidification, and purified by chromatography on SP-Sephadex C-50. Amino acid compositions, N-terminal sequences, Ouchterlony double-diffusion as well as Western blot analysis were performed. Two pepsinogens were isolated and purified from the proventriculus of the ostrich, pepsinogens I and II. Both pepsinogens and pepsins were purified to homogeneity as shown by PAGE and SDS-PAGE, with SDS-PAGE revealing M(r) values of 40,400 and 41,900 for pepsinogens I and II, respectively. SDS-PAGE revealed M(r) values of 36,000 and 36,300 for ostrich pepsins I and II, respectively. Ostrich pepsinogens I and II were found to have identical N-terminal sequences, with Asp as N-terminal amino acid. Amino acid compositions were obtained for both pepsinogens, with ostrich pepsinogen I being slightly smaller in size with a total of 356 residues compared to 371 for ostrich pepsinogen II. Pepsinogen II showed a pI of 4.29. Ostrich pepsinogens I and II were found to be immunologically separate entities, and no cross-reactivity was observed between anti-(ostrich pepsinogen I/II) sera and porcine pepsin/pepsinogen. The study indicates that only two pepsinogens are present in the ostrich. They differ in terms of electrophoretic mobility, molecular mass and immunological reactivity, but have been found to have identical N-terminal sequences. It is concluded that both pepsinogens belong to the pepsinogen A class of aspartyl proteases (EC 3.4.23.1).

Amino Acid Sequence↗

PubMed1995

Wegener's granulomatosis with relapsed bleeding of gastric ulcers: a case report.

We treated a 55-year-old male patient with Wegener's granulomatosis (WG) associated with frequent gastric bleeding from multiple ulcerative lesions. Only a few cases of frequent hemorrhaging of peptic ulcers associated with WG have been reported. In our case, a gastric biopsy showed mononuclear cell infiltration in the submucosal area, without granulomas or vasculitis. An endoscopic maneuver, as well as administration of immunosuppressive agents, combined with an H2 receptor antagonist and proton pump inhibitor successfully eliminated the gastrointestinal bleeding. In this case, proof that the gastrointestinal involvement was pathologically related to WG could not be demonstrated because neither granulomas nor vasculitis were observed in the insufficient biopsy specimen of the stomach. It is also possible that the uremic state and cytotoxic agents worsened the gastrointestinal involvement. However, immunosuppressive therapy combined with routine antiulcer treatment was very effective in repairing the ulcerative lesions. The gastrointestinal involvement was considered a possible complication of the WG.

Gastroscopy↗

PubMed1994

Ostrich (Struthio camelus) carboxypeptidase A: purification, kinetic properties and characterization of the pancreatic enzyme.

1. Carboxypeptidase A beta and carboxypeptidase A tau-type from the pancreas of the ostrich were purified by water extraction of acetone powder, aminobenzylsuccinic acid affinity and hydroxylapatite chromatography. 2. The final preparations were homogeneous when subjected to SDS-PAGE and PAGE. The M(r) values obtained from SDS-PAGE for CPA beta and CPA tau-type were 34,600 and 34,400, respectively. 3. The effects of inhibitors (1,10 phenanthroline and indole-3-acetic acid), pH and temperature on CPA activity were examined. Ki-values for CPI, PPA, D-phe, D-trp and aminobenzylsuccinic acid were determined. 4. Km, kcat and kcat/Km values were determined for hipp-phe, cbz-gly-phe, cbz-(gly)2-phe, cbz-gly-leu, cbz-(gly)2-leu and cbz-(gly)2-val. 5. N-terminal sequencing and amino acid analysis were performed for CPA beta and CPA tau-type.

Amino Acid Sequence↗

PubMed1994

Pertussis toxin-sensitive airway beta-adrenergic dysfunction by somatostatin.

To elucidate the effect of somatostatin and its mechanism of action on airway beta-adrenergic function, we studied canine bronchial smooth muscle under isometric conditions in vitro. Somatostatin (10(-6) M) inhibited the salbutamol-induced relaxation, so that the salbutamol concentration-response curves were displaced to higher concentrations (P < 0.01). This inhibition was dose dependent, the concentration of somatostatin required to produce a half-maximal effect being 10(-8) M. The relaxant responses to forskolin were likewise inhibited by somatostatin, but those to dibutyryl 3',5'--adenosine cyclic monophosphate (DB-cAMP), verapamil and nitroprusside were not. Somatostatin inhibited the salbutamol-induced accumulation of intracellular cAMP. These effects were abolished by the somatostatin antagonist cyclo [7-aminoheptanoyl-Phe-D-Trp-Lys-Thr (Bz)] or pertussis toxin. These observations suggest that somatostatin down-regulates beta-adrenergic function of airway smooth muscle through activation of an inhibitory guanine nucleotide (GTP)-binding regulatory protein, Gi, coupled to adenylate cyclase.

Adenylate Cyclase Toxin↗

PubMed1994

Interleukin-1 beta inhibits airway smooth muscle contraction via epithelium-dependent mechanism.

To determine whether the cytokine interleukin (IL)-1 beta directly affects airway smooth muscle functions and, if so, what the mechanism of action is, we studied canine isolated bronchial segments under isometric conditions in vitro. Incubation of tissues with human recombinant IL-1 beta (10 ng/ml) for 150 min decreased the contractile responses to acetylcholine, histamine, and KCl. The inhibitory effect of IL-1 beta on the acetylcholine (10(-3) M)-induced contraction was concentration-dependent, the maximal decrease from the baseline contraction being 52 +/- 8% (mean +/- SD, p < 0.001) observed with 10 ng/ml IL-1 beta. Intracellular levels of cyclic AMP and cyclic GMP were not significantly altered by IL-1 beta. The IL-1 beta-induced inhibition of the contractile responses was not affected by pretreatment of tissues with indomethacin or propranolol, but it was greatly attenuated by mechanical removal of epithelium. These results suggest that IL-1 beta may play a protective role against bronchoconstrictor responses via epithelium-dependent mechanism such as the release of epithelium-derived relaxing factor.

Acetylcholine↗

PubMed1994

Preparation of a photoactivatable fluorescent derivative of lactose and its application to photoaffinity labeling of a conger eel lectin.

A photoactivatable heterobifunctional fluorescent reagent, 1-azido-5-naphthalene sulfonyl (ANS) hydrazide, was synthesized and characterized. ANS-hydrazide reacted with lactose to form a photoactivatable hydrazone. The derivative (ANS-lactose) had the same binding affinity for a conger eel lectin as lactose judging from the hemagglutinating-inhibition assay with rabbit erythrocytes. ANS-lactose was used for photoaffinity labeling of a conger eel lectin. The photolabeled lectin was digested with chymotrypsin to isolate photolabeled peptides by reversed-phase HPLC by monitoring fluorescence. A major labeled peptide was located at positions 31-45 in the lectin by amino acid analysis and N-terminal sequencing. The identified segment was close to the highly conserved region throughout animal beta-galactoside-binding lectins.

Affinity Labels↗

PubMed1994

Nephrotic syndrome associated with subacute bacterial endocarditis (SBE): a case report.

We experienced a female nephrotic patient associated with subacute bacterial endocarditis. Her proteinuria was completely normalized after antibiotic therapy and valve replacement. Immunofluorescence and an electron microscopic study of a renal biopsy specimen showed little evidence of immune complex in the glomeruli. Marked deposition of properdin in the glomeruli and the reduced level of serum complement may indicate involvement of the complement system in the pathogenic mechanism of massive proteinuria in this case.

Adult↗

PubMed1993

Relaxation and inhibition of contractile response to electrical field stimulation by Beraprost sodium in canine airway smooth muscle.

To elucidate the effect of Beraprost, a stable prostaglandin (PG) I2 analogue, on airway smooth muscle functions and its mechanism of action, we studied canine bronchial segments under isometric conditions in vitro. Addition of PGI2 and its analogues dose-dependently relaxed bronchial smooth muscle precontracted with acetylcholine, with the rank order of potency being Beraprost (1) > or = Hoprost (0.65) > PGI2 (0.04), accompanied by the corresponding increase in intracellular cyclic AMP levels. The Beraprost- and PGI2-induced muscle relaxations were significantly inhibited by each of the PG antagonist diphloretin phosphate, the adenylate cyclase inhibitor SQ 22,536, and the Na(+)-K(+)-ATPase inhibitor ouabain. Beraprost and PGI2 at concentrations insufficient to cause muscle relaxation reduced the contractile responses to electrical field stimulation, whereas they were without effect on those to exogenous acetylcholine. These results suggest that Beraprost not only potently relaxes airway smooth muscle through cyclic AMP production and the subsequent stimulation of Na(+)-K(+)-ATPase but also reduces neurally mediated contraction by inhibiting the release of acetylcholine from the cholinergic nerve terminals.

Acetylcholine↗

PubMed1993

Atypical beta-adrenoceptor- (beta 3-adrenoceptor) mediated relaxation of canine isolated bronchial smooth muscle.

To determine whether atypical beta-adrenoceptors (beta 3-adrenoceptors) exist in the airway smooth muscle, we studied isolated bronchial segments from dogs under isometric conditions in vitro. Addition of beta-adrenoceptor agonists produced a concentration-dependent relaxation of tissues precontracted with 10(-5) M acetylcholine, rank-order potency being isoproterenol (1) > or = salbutamol (0.95) > or = BRL 37344, a beta 3-selective adrenoceptor agonist (0.83) > norepinephrine (0.10). Under the condition that alpha- and beta 1-adrenoceptors had been blocked, the relaxant response to salbutamol was competitively antagonized by the beta 2-adrenoceptor antagonist ICI 118551 and the pA2 was 7.01 +/- 0.25 (SE), whereas the response to BRL 37344 was resistant, with an apparent pA2 of 5.66. However, cyanopindolol, an antagonist for atypical beta-adrenoceptors, antagonized the BRL-induced relaxation in a competitive manner, with a pA2 of 6.74 +/- 0.11. This pA2 was lower than that when salbutamol was used as an agonist (P < 0.05). Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels were increased by BRL 37344 in a concentration-dependent fashion. These results suggest that beta 3-adrenoceptors may exist in canine bronchial smooth muscle and that the stimulation of this type of receptor causes a bronchodilation through a cAMP-dependent pathway.

Acetylcholine↗

PubMed1993

[Contribution of K-channel and Na-K-ATPase to the relaxant responses of canine bronchial smooth muscle to various bronchodilators].

To determine whether activations of K-channel and Na-K-ATPase are involved in the action of bronchodilating agents, we studied the effects of various K-channel blockers and ouabain, a Na-K-ATPase inhibitor, on the relaxant responses of canine airway smooth muscle in vitro. Addition of charybdotoxin (ChTx), a Ca-activated potassium channel blocker, and ouabain had no effect on the responses to verapamil and BRL 38227, but inhibited those to salbutamol, forskolin, DBcAMP, and nitroprusside. Apamin, a low-conductance K-channel blocker, and glibenclamide, an ATP-sensitive K-channel blocker, had no effect on the smooth muscle relaxation induced by any agents. The inhibitory effect of ChTx was predominant when the concentration of bronchodilator was low, whereas the effect of ouabain was observed in the presence of a high concentration of bronchodilator. These results suggest that Ca-activated K-channel and Na-K-ATPase may participate in the relaxation induced by bronchodilators that can raise intracellular cyclic nucleotides, and that the contribution of each component differs under different concentrations of the drugs.

Animals↗

PubMed1992

Isolation of factor Xa from chick embryo as the amniotic endoprotease responsible for paramyxovirus activation.

In chick embryo, certain paramyxoviruses mainly target the chorioallantois and the allantoamnion and show no extensive further spreading in the other organs. This has been explained by the possible presence of an endoprotease activating the viral fusion glycoprotein precursor in the allantoic and the amniotic fluid, and its absence in other places or organs. We previously isolated such an endoprotease from the allantoic fluid and demonstrated its identity with the clotting factor Xa. Exactly the same endoprotease by all the criteria including the N-terminal amino acid sequence was now isolated from the amniotic fluid. Thus, the factor Xa seems to be a major host determinant of the viral tropism in chick embryo.

Amino Acid Sequence↗

PubMed1992

Angiotensin II potentiates neurally mediated contraction of rabbit airway smooth muscle.

The effect of angiotensin II (AT II) on cholinergic neurotransmission in rabbit tracheal segments was studied under isometric conditions in vitro. AT II concentration-dependently potentiated the contractile response to electrical field stimulation (EFS), and caused a leftward shift of the frequency-response curves for EFS, so that the stimulus frequency required to produce a half-maximal effect (ES50), decreased from 7.0 +/- 0.1 to 3.0 +/- 0.1 Hz (P less than 0.01). In contrast, the contractile response to acetylcholine was not affected. Non-peptide AT II receptor antagonist CV-2961 attenuated the effect of AT II on the EFS-induced contraction. Pretreatment of tissues with thiorphan or phosphoramidon did not alter the action of AT II. Thus, AT II may prejunctionally potentiate the neurally-mediated contraction of airway smooth muscle through activation of AT II receptors on the cholinergic nerve terminals, and this effect may not be modulated by endogenous neutral endopeptidase.

Angiotensin II↗