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Biomedical subjects

A Tomoda

Publications and source records attributed to A Tomoda.

At least 73 records · Page 4Linked to original sources
PubMed1984

Involvement of oxidoreductive reactions of intracellular haemoglobin in the metabolism of 3-hydroxyanthranilic acid in human erythrocytes.

3-Hydroxyanthranilic acid, a metabolite of tryptophan, was rapidly metabolized by human erythrocytes. The final product was determined to be cinnabarinic acid as detected by spectrophotometry, paper chromatography and t.l.c. The formation of cinnabarinic acid from 3-hydroxyanthranilic acid in the cells was markedly inhibited by CO when intracellular haemoglobin was in a ferrous state, and by cyanide when it was in a ferric state. Ferrous haemoglobin in erythrocytes was oxidized to (alpha 3+ beta 2+)2, (alpha 2+ beta 3+)2 and (alpha 3+ beta 3+)2 by 3-hydroxyanthranilic acid, and the oxidation rates were very high, like those of cinnabarinic acid formation, suggesting that the metabolism of 3-hydroxyanthranilic acid is coupled with oxidoreductive reactions of intracellular haemoglobin. This view was further confirmed by the findings that 3-hydroxyanthranilic acid was metabolized by ferrous or ferric haemoglobin and that ferrous and ferric haemoglobins were oxidized and reduced by the compound respectively. The significance of the metabolism of 3-hydroxyanthranilic acid and the oxidoreductive reactions of haemoglobin with this compound may be associated with the pathological conditions with increased 3-hydroxyanthranilic acid levels in the blood of diabetic subjects.

3-Hydroxyanthranilic Acid↗
PubMed1984

Hemolytic anemia in hereditary pyrimidine 5'-nucleotidase deficiency. II. Effect of pyrimidine nucleotides and their derivatives on glycolytic and pentose phosphate shunt enzyme activity.

We evaluated the glycolytic intermediate concentrations from the erythrocytes of a patient with hereditary pyrimidine 5'-nucleotidase (P5'N) deficiency. Conclusive evidence for a metabolic block was not found. We evaluated the effects of the pyrimidine (cytidine and uridine) tri- and diphosphate nucleotides (CTP, CDP, UTP, UDP) and the choline and ethanolamine derivatives of CDP (CDP-choline, CDP-ethanolamine) on the activities of key enzymes of the Embden-Meyerhof pathway. CTP and UTP inhibited fructose-6-phosphate competitively for phosphofructokinase and phosphoenolpyruvate competitively for pyruvate kinase. In both cases, the Ki of the pyrimidine nucleotide and Km of the glycolytic substrate were above their intraerythrocytic concentrations. CTP was a competitive inhibitor of ADP for pyruvate kinase with a Ki near its intraerythrocytic concentration. CDP-choline and CDP-ethanolamine had no effect on the activities of Embden-Meyerhof or pentose phosphate shunt enzymes. Thus, the nature of the hemolytic anemia in hereditary P5'N deficiency remains enigmatic.

5'-Nucleotidase↗
PubMed1984

Isolation of human erythrocyte membranes in glucose solution.

A method is described for the preparation or removal of erythrocyte membranes from hemolysates by a glucose solution. The procedure is simple and rapid, requiring centrifugation at 8000g for 2 min. The preparation has microscopic shape and two-dimensional peptide patterns similar to those of the membrane isolated by conventional procedures (10,000g for 20 min). The present procedure is suitable for dealing with a bulky preparation or for removal of erythrocyte membranes from large volumes of hemolysates to purify enzymes and proteins of soluble or membrane fractions.

Cell Fractionation↗
PubMed1984

Oxidative and reductive reactions of sulphhaemoglobin with various reagents correlated with changes in quaternary structure of the protein.

The absorption maxima in the Soret region and near 620nm of sulphhaemoglobin shifted from 419.5nm to 423nm and from 623nm to 619nm respectively with a decrease in oxygen concentrations of the sulphhaemoglobin solution [101.3, 20.3 and 0 kPa (760, 152 and 0 mmHg) partial pressures]. The major changes in the positions of the absorption maxima occurred drastically at oxygen concentrations between 20.3 kPa and 0 kPa, suggesting that the quaternary structure of sulphhaemoglobin has changed from the R to the T state. Inositol hexaphosphate, a known allosteric effector of haemoglobin, enhanced the shift in peak location. This result supports the view that the shift of the absorption maxima reflects changes in the conformation of sulphhaemoglobin. To investigate the relationship between the conformation of sulphhaemoglobin and the reactivity of the protein with various reagents, we studied the oxidation and reduction reactions of the protein with ascorbic acid, ferricyanide and nitrite under aerobic and anaerobic conditions. The results showed that the rates of oxidation and reduction of ferrous and ferric sulphhaemoglobins with these compounds are associated with the conformation of the protein.

Ascorbic Acid↗
PubMed1984

Biphasic effects of muramyl dipeptide or lipopolysaccharide on superoxide anion-generating activities of macrophages.

The superoxide anion (O2-)-generating activity of guinea pig macrophages stimulated by wheat germ agglutinin (WGA), immune complexes, or phorbol myristate acetate (PMA) was studied after short- and long-term exposures of the cells to muramyl dipeptide (MDP) or lipopolysaccharide (LPS). Neither MDP nor LPS alone induced O2- release in macrophages. Short-term (30 min) exposure to these agents caused the enhanced release of O2- in response to WGA or immune complexes, though the PMA-induced O2- generation was not affected. On the other hand, long-term exposure (more than 24 h) to MDP or LPS progressively enhanced O2- generation of the cells induced by WGA, immune complexes, or even PMA. These results suggest that the mechanism for O2- generation of macrophages stimulated by WGA or immune complexes differs from that stimulated by PMA and that the differences also exist between short- and long-term exposure to MDP or LPS.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Mechanism of autoxidation of hemoglobin Kempsey (beta 99 Asp----Asn).

The mechanism of autoxidation of oxyhemoglobin Kempsey (beta 99 asp----asn) was studied at pH 7.0, 37 degrees C, using isoelectric focusing electrophoresis. During autoxidation, two intermediate hemoglobins, (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 were observed, and these were consecutively changed to methemoglobin. The autoxidation rates of oxyhemoglobin Kempsey were reduced about 43% by the addition of catalase and superoxide dismutase, but were not significantly changed by the addition of inositol hexaphosphate. This abnormal hemoglobin autoxidized more slowly than normal hemoglobin A. The differences in the autoxidation rates between these hemoglobins were explained by the changes in quaternary structure of these proteins. The reaction rate constant, k+1, k+2, k+3 and k+4 of each step including the reactions: (formula; see text) were determined by the analysis of fractional changes in these hemoglobin derivatives during the autoxidation. The difference in the reaction rate constants between k+1 and k+3 was explained by the nonequivalence of alpha and beta chains in tetrameric oxyhemoglobin Kempsey. The reaction mechanism of autoxidation of hemoglobin Kempsey was discussed on the basis of these kinetic results.

Asparagine↗
PubMed1984

Inhibition of the pentose phosphate shunt by lead: a potential mechanism for hemolysis in lead poisoning.

Recent investigations have disclosed a decrease in pentose phosphate shunt activity in hereditary pyrimidine 5'-nucleotidase deficiency. Clinical lead poisoning is associated with an acquired decrease in pyrimidine 5'-nucleotidase activity. The current investigations were undertaken (1) to determine if pentose shunt activity was decreased in erythrocytes exposed to lead, and (2) to compare the mechanism of inhibition to that seen in hereditary pyrimidine 5'-nucleotidase deficiency. Normal erythrocytes incubated with lead acetate in vitro demonstrated increased Heinz body formation, decreased reduced glutathione, a positive ascorbate cyanide test, and a reversible suppression of pentose shunt activity in the intact erythrocyte. Lead acetate added to normal red cell hemolysates markedly inhibited the activities of glucose-6-phosphate dehydrogenase (G6PD) and phosphofructokinase. The mean Kis of lead for glucose-6-phosphate and nicotinamide adenine dinucleotide phosphate (NADP) for G6PD were 1.5 microM and 2.1 microM, respectively, which is within the range of intraerythrocytic lead concentrations found in clinical lead poisoning. Magnesium enhanced the ability of lead to inhibit G6PD. Thus, the shortened erythrocyte survival in lead poisoning appears to be due, in part, to increased oxidant sensitivity secondary to inhibition of G6PD and the pentose shunt. The mechanism of shunt inhibition is, in part, similar to that seen in hereditary pyrimidine 5'-nucleotidase deficiency.

5'-Nucleotidase↗
PubMed1983

Effect of transmethylation-reaction and increased levels of cAMP on superoxide generation of guinea-pig macrophages induced with wheat germ agglutinin and phorbor myristate.

Superoxide (O2-) generation of guinea-pig macrophages induced by wheat germ agglutinin (WGA) was suppressed to a great extent by the inhibition of transmethylation with 3'-deazaadenosine. When macrophages were stimulated with phorbor myristate (PMA) instead of WGA, the suppression of O2- generation of macrophages was observed to be slight despite the presence of 3'-deazaadenosine. These results were confirmed under various conditions. Thus the WGA-stimulated O2- generation of macrophages is probably associated with transmethylation, but the PMA-stimulated O2- generation is not. WGA-stimulated O2- generation of macrophages was also inhibited in the presence of dibutyryl cAMP or prostaglandin E2 (PGE2), substances that increase intracellular cAMP, but PMA-stimulated O2- generation was only slightly affected by these compounds. These results suggest that the mechanism for O2- generation of macrophages caused by WGA is different from that for O2- generation caused by PMA.

Animals↗
PubMed1983

Inhibition of the pentose phosphate shunt by 2,3-diphosphoglycerate in erythrocyte pyruvate kinase deficiency.

Pentose phosphate shunt activity was studied by the release of 14CO2 from 14C-1-glucose and 14C-2-glucose in the red cells of five patients with pyruvate kinase deficiency and found to be significantly decreased after new methylene blue stimulation when compared to high reticulocyte controls. Incubated Heinz body formation was increased and the ascorbate cyanide test was positive in blood from these patients. The activity of glucose-6-phosphate dehydrogenase (G6PD) as well as that of 6-phosphogluconate dehydrogenase (6PGD) was inhibited to 20% of baseline in normal red cell haemolysate by 4 mM 2,3-diphosphoglycerate at pH 7.1. 2,3-Diphosphoglycerate was a competitive inhibitor with 6-phosphogluconate (Ki=1.05 mM) and a noncompetitive inhibitor with NADP (Ki=3.3 mM) for 6PGD. Since the intracellular concentrations of glucose-6-phosphate, 6-phosphogluconate and NADP are below their Kms for G6PD and 6PGD, the kinetic data suggest that increased concentrations of 2,3-diphosphoglycerate in pyruvate kinase deficient red cells are sufficiently high to suppress pentose phosphate shunt activity. This suppression may be an additional factor contributing to the haemolytic anaemia of pyruvate kinase deficiency, particularly during periods of infection or metabolic stress.

2,3-Diphosphoglycerate↗
PubMed1983

[Therapeutic effect of T-1982 (cefbuperazone) on the gynecologic infectious diseases].

T-1982 (cefbuperazone), a new cephamycin antibiotic with broad spectrum against Gram-positive, negative aerobic and anaerobic organisms, was clinically and bacteriologically evaluated on the gynecologic infectious diseases. Fourteen cases hospitalized at Kanazawa Medical University Hospital and the affiliated hospitals from October 1981 to July 1982 were treated with T-1982. By clinical symptoms, signs and bacteriological examinations the patients were diagnosed as pelveoperitonitis (1), intrauterine infection (3), adnexitis (3), infectious diseases of external genitalia (4), infectious abortion (1), vulvar hematoma (1), and rectovaginal fistula (1). T-1982 was administered intravenously or by drip infusion at a dose of 0.5-2.0 g twice a day after dissolved in a saline solution or a 5% glucose solution. Based on the improvement of clinical findings and antibacterial effect of T-1982, results were evaluated as excellent, good, poor and unknown. Clinical effects more than good were shown in 9 of 11 cases which could be followed up exactly on the therapeutic of T-1982. Two cases showing poor response were pelveoperitonitis and pyometra under carcinoma colli uteri stage IIIb, respectively. In 8 of 11 cases, antibacterial effect of T-1982 could be evaluated. Thirteen strains of aerobic and anaerobic bacteria were disappeared by T-1982 therapy, while no effect was seen on 5 strains. On the side effect of T-1982, exanthema was observed in 1 case but disappeared soon after the cessation of administration.

Adult↗
PubMed1983

Oxido-reductive reactions of sulfhemoglobin with various reagents associated with changes in conformation of the protein.

The optical peaks at Soret region and near at 620 nm of sulfhemoglobin (sulfHb) shifted from 419.5 nm to 423 nm and from 623 nm to 619 nm, respectively, according to the decrease in oxygen concentrations of the sulfHb solution (1 atm to zero atm). This shift of optical peaks was strengthened by the addition of inositol hexaphosphate (P6-inositol), a strong allosteric effector of Hb. Thus the shift of the optical peaks seems to reflects the changes in conformation of sulfHb. In order to clarify the relationship between the conformation of sulfHb and the reactivity of the protein with various reagents, we studied the oxidation and reduction reaction of the protein with ascorbic acid, ferricyanide and nitrite under aerobic and anaerobic conditions. The results suggested that the rate of oxido-reductive reactions of ferrous and ferric sulf Hbs with these compounds are associated with the conformation of the protein.

Ascorbic Acid↗
PubMed1982

Hemolytic anemia in hereditary pyrimidine 5'-nucleotidase deficiency: nucleotide inhibition of G6PD and the pentose phosphate shunt.

We evaluated the erythrocytes of two patients with hereditary pyrimidine 5'-nucleotidase deficiency. Significant findings included an increased reduced glutathione content, increased incubated Heinz body formation, a positive ascorbate cyanide test, and decreased intraerythrocytic pH. The pentose phosphate shunt activity of the patients' red cells as measured by the release of 14CO2 from 14C-1-glucose was decreased compared to high reticulocyte controls. Glucose-6-phosphate dehydrogenase (G6PD) activity in hemolysates from control erythrocytes was inhibited 43% by 5.5 mM cytidine 5'-triphosphate (CTP) and 50% by 5.5 mM in uridine 5'-triphosphate (UTP) at pH 7.1. CTP was a competitive inhibitor for G6P (Ki = 1.7 mM) and a noncompetitive inhibitor for NADP+ (Ki = 7.8 mM). Glutathione peroxidase, glutathione reductase, and 6-phosphogluconate dehydrogenase were not affected by these compounds. Pentose phosphate shunt activity in control red cell hemolysate at pH 7.1 was inhibited to a similar degree by 5.5 mM CTP or UTP. Since the intracellular concentrations of G6P and NADP+ are below their KmS for G6PD, these data suggest that high concentrations of pyrimidine 5'-nucleotides depress pentose phosphate shunt activity in pyrimidin 5'-nucleotidase deficiency. Thus, this impairment of the pentose phosphate pathway appears to contribute to the pathogenesis of hemolysis in pyrimidine 5'-nucleotidase deficiency hemolytic anemia.

5'-Nucleotidase↗
PubMed1981

Reduction of methemoglobin by ferredoxin and ferredoxin-NADP reductase system.

The changes in absorption spectra between 450 and 650 nm during the reduction of methemoglobin A, (alpha 2+ beta 3+)2, and (alpha 3+ beta 2+)2 valency hybrids by the system including ferredoxin and ferredoxin-NADP reductase were studied under anaerobic conditions. During the reduction of methemoglobin A, the isosbestic points gradually shifted to different positions. These shifts were clearly observed in the presence of inositol hexaphosphate, i.e. the isosbestic points were initially observed at 525 and 603 nm, and these shifted to 529 and 599 nm, respectively, suggesting that the intermediate hemoglobins are produced during the process of the reaction. This was confirmed by the isoelectric focusing electrophoresis of the partially reduced methemoglobin solutions with ferredoxin-NADP reductase system on Ampholine-polyacrylamide gel plate. On the other hand, the absorption spectra of alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 changed with excellent isosbestic points during th reductive reaction by ferredoxin-NADP reductase system, i.e. (alpha 2+ beta 3+)2 at 526 and 601 nm and (alpha 3+ beta 2+)2 at 529 and 599 nm. From these results, the mechanism of methemoglobin reduction by ferredoxin-NADP reductase system was suggested. 1) There are two pathways for the reduction of methemoglobin including (formula, see text). 2) The beta chains of methemoglobin may be more susceptible to the reduction than the alpha chains in tetrameric methemoglobin, and thereby the (alpha 3+ beta 2+)2 valency hybrid accumulated at the halfway point of the reaction. 3) The shift in isosbestic points of methemoglobin reduction (525 nm leads to 529 nm, 603 nm leads to 599 nm) is due to the accumulation of (alpha 3+ beta 2+)2, whose isosbestic points during the reduction by the ferredoxin-NADP reductase systems were 529 and 599 nm.

Ferredoxin-NADP Reductase↗
PubMed1981

Changes in intermediate haemoglobins during autoxidation of haemoglobin.

The time course of haemoglobin autoxidation was studied under various conditions at 37 degrees C, and the changes in oxyhaemoglobin, intermediate haemoglobins and methaemoglobin during the reaction were analysed by isoelectric focusing on Ampholine/polyacrylamide-gel plates. Under various conditions (10 mM-phosphate buffer, 10 mM-phosphate buffer with 0.1 M-phosphate buffer, 10 mM-phosphate buffer with 0.1 M-NaCl, and 10 mM-phosphate buffer with 0.5 mM-inositol hexaphosphate; pH range 6.6-7.8 each case), the intermediate haemoglobins were found to be present as (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 valency hybrids from their characteristic positions on electrophoresis. Oxyhaemoglobin changed consecutively to (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2, which were further oxidized to methaemoglobin, and the amounts of (alpha 3+beta 2+)2 were greater than those of (alpha 2+ beta 3+)2 during the reaction. The modes of the quantitative changes in oxyhaemoglobin, intermediate haemoglobins, and methaemoglobin were very similar in all the media used except for the inositol hexaphosphate addition. In the presence of inositol hexaphosphate, the autoxidation rates were considerably accelerated, and the modes of the changes in the haemoglobin derivatives were also considerably altered; the effects of this organic phosphate were maximal at acidic pH and minimal at alkaline pH. It was concluded that haemoglobin autoxidation proceeds by first-order kinetics through two paths: and (formula: see text). The reaction rate constants (k+1-k+4) best fitting all experimental values obtained by the isoelectric-focusing analysis were evaluated. By using these values, the mechanism of haemoglobin autoxidation is discussed.

Hemoglobins↗
PubMed1981

Involvement of superoxide anion in the reaction mechanism of haemoglobin oxidation by nitrite.

The sigmoidal time course of haemoglobin oxidation by nitrite, involving an initial slow reaction accompanied by a subsequent rapid reaction, was extensively explored. The initial slow reaction was much prolonged by the addition of superoxide dismutase to the reaction mixture. On the other hand, in the presence of superoxide anion generated by xanthine oxidase systems, the slow phase disappeared and the reaction changed to first-order kinetics. The oxidation of intermediate haemoglobins [defined as haemoglobin tetramer in which different chains (alpha- or beta-) are in the ferric state and in the ferrous state] such as (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 also proceeded in a sigmoidal manner. Similar effects of superoxide anion on these reactions were observed. Since the intermediate haemoglobins such as (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 were found to be produced by the oxidation of haemoglobin by nitrite, the changes in oxyhaemoglobin, intermediate haemoglobins and methaemoglobin during the reaction were followed by isoelectric-focusing electrophoresis. The amounts of (alpha 2+ beta 3+)2 were larger than those of (alpha 3+ beta 2+)2 at the initial stages of the reaction, suggesting that there is a functional difference between alpha- and beta-chains in the oxyhaemoglobin tetramer. On the basis of these results, a reaction model of the haemoglobin oxidation by nitrite was tentatively proposed. The changes in oxyhaemoglobin, intermediate haemoglobins and methaemoglobin were well fitted to the simulation curves generated from the reaction model. Details of the derivation of the equations used for kinetic analysis have been deposited as Supplement SUP 50112 (5 pages) with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K. from whom copies may be obtained on the terms indicated in Biochem. J. (1978) 169, 5.

Catalase↗