Search PubMed⌕ Search

Biomedical subjects

M Saito

Publications and source records attributed to M Saito.

At least 181 records · Page 10Linked to original sources
PubMed2001

The specificity of monoclonal antibody A2B5 to c-series gangliosides.

To examine the specificity of monoclonal antibody A2B5, four A2B5-reactive gangliosides (designated as G-1, G-2, G-3 and G-4) were purified from bonito fish brain. Ganglioside-1, -2, and -3 migrated above GD1b, below GQ1b, and far below GQ1b on thin-layer chromatography. Ganglioside-4 had the slowest chromatographic mobility and migrated below G-3. The structures of these gangliosides were characterized by overlay analysis with glycolipid-specific ligands, product analysis after sialidase or mild acid treatment, and electrospray ionization-mass spectrometry (ESI-MS). Accordingly, G-1, G-2 and G-3 were identified to be GT3, GQ1c and GP1c, respectively. The ganglioside G-4 was shown to have the following structure: NeuAc-NeuAc-NeuAc-Galbeta1-3Gal NAcbeta1-4(NeuAc-NeuAc-NeuAcalpha2-3)Galbeta1-4Glcbeta1-1'Cer. The antibody A2B5 reacted with these c-series gangliosides, but not with GD3 and other gangliosides and neutral glycosphingolipids. The antigenic epitope for A2B5 was assumed to include the trisialosyl residue connected to the inner galactose of the hemato- or ganglio-type oligosaccharide structure of gangliosides. Phylogenetic analysis of brain gangliosides using the A2B5 preparation demonstrated that c-series gangliosides are enriched in lower animals, especially bony fish of different species. The monoclonal antibody A2B5 would be a useful tool for examining the distribution and function of c-series gangliosides.

Animals↗
PubMed2001

Status of platelet collection and platelet transfusion.

Platelet product derived from single donor plateletpheresis is required to reduce the risks of adverse reactions by blood transfusion. The objectives of this study are to evaluate the status of platelet collection and its efficacy by various kinds of plateletpheresis equipment and to assess the achievement of platelet transfusion by platelet product derived from a single donor. Since the blood centers have introduced some kinds of efficient plateletpheresis equipment, large units of platelet products have been supplied mainly for the patients. Amicus and CCS might be preferable plateletpheresis machines because of their collection efficiencies and wider indication for donors. The average number of donors of platelet product per patient has recently reached nearly 1.0, and around 90% of patients have received platelet product derived from a single donor in the recent several years. However, platelet transfusion derived from a single donor has not yet been completely achieved. Each regional blood center should seriously consider the efficacy of each plateletpheresis equipment and arrange the equipment to collect platelets more effectively to achieve platelet transfusion from a single donor.

Blood Platelets↗
PubMed2001

Effect of YM-40461, a novel surfactant secretagogue, on chronic obstructive pulmonary diseases and similar symptoms in guinea pigs.

YM-40461 (1-(2-dimethylaminoethyl)-1-(3,4,5-trimethoxyphenyl)urea, CAS 142912-85-4), is a novel surfactant secretagogue. The effect of YM-40461 on symptoms, e.g. change of airway functions and hypoxemia, were examined using guinea pigs with induced subacute bronchitis. Bronchitic guinea pigs exhibited basal lung resistance (RL) was 0.152 +/- 0.005 cm H2O/ml/s (normal: 0.130 +/- 0.002 cm H2O/ml/s) and basal lung compliance (CL) of 0.455 +/- 0.011 ml/cm H2O (normal: 0.509 +/- 0.009 ml/cm H2O). Although YM-40461 slightly improved the lung resistance in these animals, it improved significantly and dose-dependently the lung compliance (0.468 +/- 0.008 ml/cm H2O for 1 mg/kg, 0.477 +/- 0.008 for 3 mg/kg, 0.490 +/- 0.011 for 10 mg/kg, p < 0.05 at 10 mg/kg) compared to nontreated bronchitic guinea pigs. YM-40461 improved airway functions in bronchitic guinea pigs just as wall as the beta 2-adrenoceptor agonist salbutamol. Additionally, YM-40461 significantly reduced airway hyperreactivity in response to intravenously infused acetylcholine (ACh). Basal PaO2 was 83.1 +/- 0.7 cm H2O in healthy guinea pigs and 71.2 +/- 1.7 cm H2O in bronchitic guinea pigs, indicating hypoxemia. A dose of 10 mg/kg of YM-40461 relieved hypoxemia in these animals with the values returning to 81.8 +/- 1.9 cm H2O (p < 0.05). These results suggest that YM-40461 ameliorates chronic obstructive pulmonary disease (COPD)-like symptoms in bronchitis models due to increased surfactant in the airway.

Acetylcholine↗
PubMed2001

Dietary supplementation of N-3 fatty acids and hydroperoxide levels in rat retinas.

Docosahexaenoic acid (DHA) plays an important role in visual and neural development in mammals. In the present study, effect of dietary supplementation with n-3 fatty acids, primarily docosahexaenoic acid (DHA) with high purity, on the fatty acid composition of photoreceptor cells of young rats (fed from 4 weeks) was investigated. DHA in rod outer segment (ROS) membranes was significantly increased in the group of high DHA feeding (9.69% total energy). Other n-3 fatty acids (alpha-linolenic acid (ALA) and eicosapentaenoic acid (EPA)) included in the diets with DHA (0.95%-5.63% total energy) also significantly increased the proportion of DHA compared with the linoleic acid diet groups. However, the proportions of arachidonic acid (ARA) and other long chain n-6 fatty acids (22:4n6 and 22:5n6) were suppressed in these n-3 fatty acids-fed groups. Phospholipid hydroperoxides in ROS membranes were determined using a highly sensitive analytical technique, chemiluminescence-high performance liquid chromatography (CL-HPLC). There was no increasing tendency in the hydroperoxide levels of ROS membranes containing high content of DHA, and phosphatidylethanolamine hydroperoxide (PEOOH) was much lower than phosphatidylcholine hydroperoxide (PCOOH) under normal light conditions, which implies that DHA supplementation does not much affect the peroxidizability of ROS membranes in vivo. But UV irradiation on separated ROS membranes accelerated the formation of phospholipid hydroperoxides in high DHA feeding rats, and PEOOH was produced more efficiently than PCOOH in vitro.

Animals↗
PubMed2001

Radical production and cytotoxic activity of tert-butyl-substituted phenols.

2,4,6-Tri-tert-butylphenol (TBP)-related compounds are used for stabilizing plastics by making them resistant to oxidation. However, the cytotoxic activity of these compounds has not yet been established. TBP produced phenoxyl radicals at pH >or= 9.0 and 2,4-di-t-butylphenol (DBP) at pH 12.5, but 3,3',5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-diol (bisDBP) did not, using ESR spectroscopy. Both superoxide anion radical (O(2)(-)) scavenging activity and reactive oxygen species (ROS) production activity declined in the order of TBP > DBP > bisDBP. The cytotoxic activity against human oral tumor cell lines (HSC-2, HSG) and human gingival fibroblast cells (HGF) declined in the order of DBP >> bisDBP = TBP = TBP-OOH (2,4,6-tri-t-butyl-4-hydroperoxy-2,5-cyclohexadiene-1-one). The cytotoxic activity of TBP, but not of DBP or bisDBP was significantly enhanced after visible light (VL)-irradiation for 10 min. The cytotoxicity of irradiated TBP was significantly higher than that of either original TBP or TBP-OOH, the oxidative metabolite of TBP, possibly due to the formation of TBP stable radical and ROS via oxidation. In contrast, the cytotoxic activity of DBP and bisDBP was independent of radical production, and therefore, may be intrinsic. A non-enzymatic oxidation decomposition of DBP or TBP was estimated from the formation of reaction enthalpy (DeltaH) using a modified neglect of diatomic overlap, parametric method 3 (MNDO-PM3) semi-empirical method, suggesting that O(2) is capable of activating DBP to a reactive quinone or dimer and that TBP phenoxyl radicals via oxidation directly affect extra- or intracellular bioactive materials, resulting in the induction of cytotoxicity.

Antioxidants↗
PubMed2001

Telomerase-inhibitory effects of the triphosphate derivatives of some biologically active nucleosides.

Telomerase is a ribonucleoprotein reverse transcriptase that uses its internal RNA moiety as a template for synthesis of telomere repeats. To clarify the susceptibility of telomerase to HIV-1 reverse transcriptase inhibitors (RT), we investigated the inhibitory effects of 3'-azido-3'-deoxythymidine 5'-triphosphate (AZTTP), which is known to be a potent HIV-1 RT inhibitor, and acyclovir triphosphate (ACVTP). Lineweaver-Burk plot analyses showed that the inhibition mode of these compounds was competitive with the substrate dNTP counterpart. However, inhibition by AZTTP was weak (Ki = 15 microM, Km of dTTP = 7.1 microM). Interestingly, ACVTP showed considerable inhibition. The Ki value of ACVTP was 5.0 microM, being smaller than the Km of dGTP (12 microM).

Acyclovir↗
PubMed2001

Serine acetyltransferase involved in cysteine biosynthesis from spinach: molecular cloning, characterization and expression analysis of cDNA encoding a plastidic isoform.

A cDNA clone that encodes a chloroplast-localizing isoform of serine acetyltransferase (SATase) (EC 2.3.1.30) was isolated from spinach (Spinacia oleracea L.). The cDNA encodes a polypeptide of 347 amino acids containing a putative transit peptide of ca. 60-70 amino acids at the N-terminal. Deduced amino acid sequence of SATase from spinach exhibited homology with other SATases from plants. DNA blot hybridization analysis showed the presence of 2-3 copies of Sat gene in the genome of spinach. RNA blot hybridization analysis indicated the constitutive expression of Sat gene in green and etiolated seedlings of spinach. Bacterial expression of the cDNA could directly rescue the cysteine auxotrophy of Escherchia coli caused by a lack of SATase locus (cysE). Catalytically active SATase protein was produced in E. coli cells. L-Cysteine, an end product of the cysteine biosynthetic pathway, inhibited the activity of recombinant spinach SATase, indicating the regulatory function of SATase in this metabolic pathway. A chloroplastic localization of this spinach SATase was revealed by the analyses of transgenic plant expressing transit peptide of SATase-beta-glucuronidase (GUS) fusion protein, and transient expression using the transit peptide-green fluorescent protein (GFP) fusion protein. The result from in vitro translation analysis suggests that this cDNA may encode both plastidic and cytosolic SATases.

Acetyltransferases↗
PubMed2001

A dose-response study of anticholinesterase drugs on contractile and phosphatidylinositol responses of rat trachea.

UNLABELLED: We investigated whether anticholinesterase drugs in large doses inhibit muscarinic receptors of airway smooth muscle. In vitro measurements of isometric tension and [(3)H]inositol monophosphate (IP(1)) that formed were conducted by using rat tracheal rings or slices. Neostigmine and pyridostigmine caused muscular contraction and IP(1) accumulation in small doses (10 microM and < or = 100 microM, respectively), but they attenuated muscular contraction and IP(1) accumulation in larger doses (1000 microM). Edrophonium did not affect the smooth muscle tone and IP(1) levels. Neostigmine, pyridostigmine, and edrophonium attenuated the carbachol (5.5 microM)-induced smooth muscle contraction and IP(1) accumulation, when administered in large doses (1000 microM). The attenuation of contraction by neostigmine at large doses was not affected by methoctramine, an M(2) muscarinic receptor antagonist, but was reversed by washing with fresh Krebs-Henseleit solution. The results suggest that anticholinesterase drugs have dual effects on the tension and phosphatidylinositol responses of rat trachea. Large doses of anticholinesterase drugs cause airway smooth muscle relaxation, which may be seen in patients with myasthenia gravis who have received excessive anticholinesterase therapy. IMPLICATIONS: Neostigmine and pyridostigmine, but not edrophonium, have dual effects on the tension and phosphatidylinositol responses of rat trachea. Large doses of anticholinesterase drugs cause airway smooth muscle relaxation, which may be seen in patients with myasthenia gravis who have received excessive anticholinesterase therapy.

Animals↗
PubMed2001

Elevated levels of free tissue factor pathway inhibitor antigen in cases of disseminated intravascular coagulation caused by various underlying diseases.

Tissue factor pathway inhibitor (TFPI) is primarily synthesized by vascular endothelial cells and is found in vivo in association with endothelial cells, lipoproteins, or in free form. Free TFPI is the most potent and important type, because it is released from endothelial cells following an injection of heparin, or as a result of pathological stimuli. In order to study the role of TFPI in disease, the concentration of free form TFPI was measured in the plasma of 114 patients suffering from disseminated intravascular coagulation (DIC), as the result of several underlying diseases. Plasma antigen levels of free TFPI were significantly higher even in those patients not exhibiting DIC than in normal healthy subjects. These levels were even higher among patients exhibiting DIC, especially those with acute promyelocytic leukemia or cancer, receiving continuous heparin drip infusions. A significant correlation was observed between the plasma antigen levels of free form TFPI and those of fibrin/fibrinogen degradation products, and free form TFPI and plasmin inhibitor complex (r = 0.428, P < 0.0001 and r = 0.329, P < 0.0001, respectively) among 114 DIC patients. There were no significant differences between the plasma levels of free TFPI in DIC patients with or without multiple organ failure. It has been suggested that the plasma levels of free TFPI are closely related to the levels of fibrinolysis occurring in DIC patients, although further study is required to clarify the degree to which TFPI is expressed by endothelial cells during DIC.

Case-Control Studies↗
PubMed2001

Depressed plasma activity of plasminogen or alpha2 plasmin inhibitor is not due to consumption coagulopathy in septic patients with disseminated intravascular coagulation.

We have attempted to determine whether depressed plasma plasminogen and alpha2 plasmin inhibitor (or alpha2 antiplasmin) activity is, as a result of consumption coagulopathy, a specific finding of disseminated intravascular coagulation (DIC) in septic patients. The hemostatic parameters of 139 septic patients (68 with DIC and 71 without DIC) were analyzed. Among the group as a whole, plasma activities of plasminogen and alpha2 plasmin inhibitor were significantly depressed in septic patients with DIC relative to those without DIC (P < 0.01 and P < 0.05, respectively). Notably, a significant correlation was observed between plasma levels of albumin and plasminogen activity, as well as between plasma levels of albumin and alpha2 plasmin inhibitor activity both in septic patients with DIC and those without DIC. However, no significant correlation was observed between plasma levels of plasmin-alpha2 plasmin inhibitor complex (PIC) and plasminogen activity, nor between PIC and alpha2 plasmin inhibitor activity either in septic patients with DIC or those without DIC. We concluded that depressed activity of plasminogen or alpha2 plasmin inhibitor is not as a result of consumption coagulopathy, but rather a result of low synthetic function of the liver in septic patients with DIC.

Aged↗
PubMed2001

All-trans retinoic acid is partially effective against lipopolysaccharide-induced but not against tissue-factor-induced disseminated intravascular coagulation in rat models.

All-trans retinoic acid (ATRA) has been introduced to the management of acute promyelocytic leukemia (APL) as a differentiation treatment. This drug not only causes complete remission, but also improves disseminated intravascular coagulation (DIC) without adding anticoagulants in APL. We have attempted to determine whether ATRA is effective against DIC in rat models induced by tissue factor (TF) or lipopolysaccharide (LPS), because the anticoagulant effect of ATRA has been considered to induce thrombomodulin upregulation and TF downregulation on endothelial cells as well as on APL cells. In male Wistar rats, DIC was induced by a 4-h infusion of thromboplastin (3.75 U/kg) or lipopolysaccharide (30 mg/kg). The rats were given ATRA orally each day at a dose of 100 mg/kg per day for 1 week before the injection of TF or LPS in ATRA treatment groups, or given low molecular weight heparin (LMWH) 10 min before the injection of TF or LPS (200 U/kg, bolus intravenously) in LMWH treatment groups. No significant changes in hemostatic parameters or markers of organ dysfunction were caused by the ATRA administration, while DIC was significantly improved by LMWH in the TF-induced model. DIC was significantly improved by both ATRA and LMWH in the LPS-induced model. These findings suggested that ATRA was useful for treating DIC only in the LPS-induced model, and that drug efficacy should be carefully assessed because the agents used to induce DIC considerably influenced the outcome.

Animals↗
PubMed2001

An enhanced fibrinolysis prevents the development of multiple organ failure in disseminated intravascular coagulation in spite of much activation of blood coagulation.

OBJECTIVES: To investigate the relationship between fibrinolytic enhancement and the development of multiple organ failure (MOF) in disseminated intravascular coagulation (DIC). To detect the useful prognostic index for outcome in DIC. DESIGN: Case-control study. SETTING: A department of internal medicine in a university hospital, a clinical division for diagnosis and treatment, mainly of respiratory diseases, hematologic diseases, DIC, and other diseases requiring critical care medicine. PATIENTS: A total of 69 DIC patients, 31 with MOF. INTERVENTIONS: None. MEASUREMENT AND MAIN RESULTS: The DIC patients with MOF had more elevated levels of tissue plasminogen activator antigen (t-PA) and plasminogen activator inhibitor antigen (PAI), and more depressed levels of plasmin-alpha2 plasmin inhibitor complex (PIC) and fibrin/fibrinogen degradation products than those without MOF, although no significant difference in thrombin-antithrombin complex (TAT) levels was observed. A fibrinolytic enhancement (shown by PIC) was parallel to an activation of blood coagulation (shown by TAT) in DIC patients without MOF, although no such fibrinolytic enhancement was provoked even by much activation of blood coagulation in DIC patients with MOF. Whereas all the patients without MOF were restored from DIC, 14 of 31 patients with MOF were unable to be restored from DIC and died. A significant increase in plasma levels of t-PA and PAI under the condition of sustained hemostatic activation was observed in the patients who died. CONCLUSION: Enhanced fibrinolysis was considered to be the important defense mechanism in preventing the development of MOF in DIC. The increases in plasma levels of t-PA and PAI were poor prognostic markers in DIC. Further careful study may be useful to clarify whether the fibrinolytic therapy is beneficial in clinical DIC patients with MOF.

Antifibrinolytic Agents↗
PubMed2001

Dose absorbed by mouse red bone marrow after oral administration of tritiated water.

Tritiated water (HTO) was given to mice orally. Dose accumulation patterns in various organs and tissues after oral HTO intake were compared with those after intraperitoneal injection. The accumulated dose was 10-20% higher after intraperitoneal injection than after oral administration. A new technique was developed to isolate mouse red bone marrow from tibia. The absorbed beta-ray dose in the red bone marrow after oral tritium intake was lower than the body-averaged dose that was estimated based on the tritium concentration in the urine or the blood and higher than the absorbed dose in the liver and testis.

Absorption↗
PubMed2001

Molecular forms of plasma and urinary adrenomedullin in normal, essential hypertension and chronic renal failure.

OBJECTIVES: Human adrenomedullin precursor is converted to glycine-extended adrenomedullin (AM-Gly), an intermediate inactive form of adrenomedullin. Subsequently, AM-Gly is converted to active form of mature adrenomedullin (AM-m). The aim of the present study was to investigate (i) whether sex or age influences plasma and urinary AM-m and AM-Gly levels in normal subjects; (ii) the daytime variability of plasma AM-m and AM-Gly levels in normal subjects; (iii) AM-m and AM-Gly levels and its ratio in plasma and urine in normal subjects, individuals with essential hypertension (HT), and chronic renal failure (CRF); and (iv) the ratio of AM-m and AM-total (T) in plasma of various veins and aorta. METHODS: We measured plasma levels and urinary excretions of AM-m, AM-Gly and AM-T (AM-m + AM-Gly) by recently developed immunoradiometric assay in normal subjects (n = 81), HT (n = 28) and CRF (n = 30). We also determined the molecular forms of plasma adrenomedullin taken from various sites during angiography in patients with suspected renovascular hypertension (n = 9). RESULTS: There were no differences in plasma and urinary excretions of two molecular forms of adrenomedullin among sexes or ages in normal subjects. There was no daytime variation of plasma two molecular forms of adrenomedullin in normal subjects. Plasma AM-m, AM-Gly and AM-T levels were increased in patients with HT and CRF compared with normal subjects, whereas urinary AM-m, AM-Gly and AM-T excretions were decreased in patients with HT and CRF compared with normal subjects. Urinary AM-m: AM-T ratios were significantly higher than plasma AM-m: AM-T ratios. Plasma AM-m and AM-T levels taken from various veins were similar, and they were significantly higher than those of aorta, although there were no differences in plasma AM-Gly levels between aorta and veins. CONCLUSIONS: These results suggest that in normal subjects, and individuals with HT and CRF: (i) plasma and urinary excretions of AM-m and AM-Gly are not affected by age or sex; (ii) AM-m in parallel with AM-Gly is increased; (iii) urine contains a higher percentage of active adrenomedullin than plasma; and (iv) plasma AM-m may be partly metabolized in the lung.

Adrenomedullin↗
PubMed2001

Cysteine synthase overexpression in tobacco confers tolerance to sulfur-containing environmental pollutants.

Cysteine (Cys) synthase [O-acetyl-L-Ser(thiol)-lyase, EC 4.2.99.8; CSase] is responsible for the final step in biosynthesis of Cys. Transgenic tobacco (Nicotiana tabacum; F(1)) plants with enhanced CSase activities in the cytosol and in the chloroplasts were generated by cross-fertilization of two transformants expressing cytosolic CSase or chloroplastic CSase. The F(1) transgenic plants were highly tolerant to toxic sulfur dioxide and sulfite. Upon fumigation with 0.1 microL L(-1) sulfur dioxide, the Cys and glutathione contents in leaves of F(1) plants were increased significantly, but not in leaves of non-transformed control plants. Furthermore, the leaves of F(1) plants exhibited the increased resistance to paraquat, a herbicide generating active oxygen species.

Adaptation, Physiological↗
PubMed2001

Stabilization of hen egg white lysozyme by a cavity-filling mutation.

Stabilization of a protein using cavity-filling strategy has hardly been successful because of unfavorable van der Waals contacts. We succeeded in stabilizing lysozymes by cavity-filling mutations. The mutations were checked by a simple energy minimization in advance. It was shown clearly that the sum of free energy change caused by the hydrophobicity and the cavity size was correlated very well with protein stability. We also considered the aromatic-aromatic interaction. It is reconfirmed that the cavity-filling mutation in a hydrophobic core is a very useful method to stabilize a protein when the mutation candidate is selected carefully.

Animals↗
PubMed2001

Delayed onset of systemic bacterial dissemination and subsequent death in mice injected intramuscularly with Streptococcus pyogenes strains.

Streptococcus pyogenes causes severe invasive diseases in humans, including necrotizing fasciitis, sepsis, and streptococcal toxic shock syndrome (STSS). We found that mice infected intramuscularly (i.m.) with S. pyogenes strains developed bacteremia and subsequent sudden death after at least 10 days of a convalescent period. Mostly, it occurred more than 21 days after muscle infection. We provisionally designate this phenomenon as "delayed death." Just after muscle infection, all the mice lost weight and activity, but recovered completely within 3 days. They had kept good activity and a fine coat of fur till one or two days before their death. Some of the dead mice were found to have soft-tissue necrosis. There was no correlation between the virulence leading to the delayed death and the severity of diseases from which strains were isolated. It was also found that the production of neither streptococcal pyrogenic exotoxin (SPE) A nor B correlated to the virulence leading to delayed death. The bacteria obtained from the organs of the mice with delayed death expressed capsule. We suggest that the mice with delayed onset of systemic bacterial dissemination and subsequent death after muscle infection with S. pyogenes are the animal models of STSS, because the pathophysiology is extremely similar to that of human STSS.

Animals↗