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Biomedical subjects

M Uozumi

Publications and source records attributed to M Uozumi.

16 recordsLinked to original sources
PubMed1990

Facilitated transport of oxygen through hemoglobin solutions.

A method for quantitative analysis of hemoglobin color to estimate the oxygen saturation was developed. The method uses an image-input and -processing system composed of a 3-tube video camera and a digital image analyzer. When the system is connected to a microscope, the facilitated diffusion of oxygen in hemoglobin solutions can be observed and analyzed in a position-sensitive manner. The results led to a new transport model expressed as: J = k'CY/d, where J is the oxygen flux, C is the hemoglobin concentration, Y is the oxygen saturation of hemoglobin, d is the distance between the entrance of oxygen and the diffusion front, and k' is a constant.

Algorithms↗
PubMed1990

Decrease of nitrate biosynthesis in scorbutic mutant rats unable to synthesize ascorbic acid.

The effect of ascorbic acid deficiency on the urinary excretion of nitrate was investigated using a mutant strain of rats (osteogenic disorder syndrome rats; ODS rats) unable to synthesize ascorbic acid. The amount of urinary nitrate excreted by ODS rats with or without ascorbic acid supplementation were measured before and after the intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS). Urinary nitrate excretion increased markedly after LPS injection. Urinary nitrate excretion by ODS rats not supplied with ascorbic acid was significantly less than that of those supplied with ascorbic acid both before and after LPS injection. These results show that ascorbic acid enhances both LPS-stimulated and constitutive nitrate production in vivo.

Adrenal Glands↗
PubMed1990

Marked nitrosation by stimulation with lipopolysaccharide in ascorbic acid-deficient rats.

Marked formation of N-nitrosothioproline (N-nitrosothiazolidine-4-carboxylic acid) by stimulation with Escherichia coli lipopolysaccharide (LPS) was demonstrated in ascorbic acid-deficient mutant rats (osteogenic disorder syndrome rats; ODS rats) unable to synthesize ascorbic acid. The amounts of urinary nitrate and N-nitrosothioproline excretion after thioproline administration was measured in ODS rats with and without ascorbic acid supplement before and after the injection of LPS. LPS caused marked increase of urinary nitrate excretion in both groups. Urinary N-nitrosothioproline excretion increased 6-fold after LPS injection in ODS rats not supplied with ascorbic acid, but supplement with ascorbic acid markedly decreased the excretion of N-nitrosothioproline.

Adrenal Glands↗
PubMed1989

Proteinic prorenin-releasing-stimulator (PRS) in the rat submandibular gland.

The release of prorenin as well as renin from rat renal slices was confirmed by a rat prorenin-prosegment ELISA system and an assay system for determining the renin activity. A significant increase of the prorenin release was found by adding rat submandibular gland extract to the slice medium, indicating the existence of a prorenin-releasing stimulator (PRS) in the extract. The pI and molecular mass of PRS were 8.5-8.7 and 28-30 kDa, respectively. The PRS was completely inactivated by boiling or a proteinase treatment.

Animals↗
PubMed1989

The interaction between nitrogen oxides and hemoglobin and endothelium-derived relaxing factor.

Among nitrogen oxides, NO and NO2 are free radicals and show a variety of biological effects. NO2 is a strongly oxidizing toxicant, although NO, not oxidizing as NO2, is toxic in that it interacts with hemoglobin to form nitrosyl- and methemoglobin. Nitrosylhemoglobin shows a characteristic electron spin resonance (ESR) signal due to an odd electron localized on the nitrogen atom of NO and reacts with oxygen to yield nitrate and methemoglobin, which is rapidly reduced by methemoglobin reductase in red cells. NO was found to inhibit the reductase activity. Part of NO inhaled in the body is oxidized by oxygen to NO2, which easily dissolves in water and converts to nitrite and nitrate. The nitrite oxidizes oxyhemoglobin autocatalytically after a lag. The mechanism of the oxidation, particularly the involvement of superoxide, was controversial. The stoichiometry of the reaction has now been established using nitrate ion electrode and a methemoglobin free radical was detected by ESR during the oxidation. Complete inhibition of the autocatalysis by aniline or aminopyrine suggests that the radical catalyzes conversion of nitrite to NO2, which oxidizes oxyhemoglobin. Recently NO was shown to be one of endothelium-derived relaxing factors and the relaxation induced by the factor was inhibited by hemoglobin and potentiated by superoxide dismutase.

Free Radicals↗
PubMed1988

Color analysis method for studying oxygen transport in hemoglobin solutions using an image-input and -processing system.

A method for quantitative analysis of hemoglobin color to estimate the oxygen saturation was developed. The method uses an image-input and -processing system composed of a 3-tube video camera and a digital image analyzer. Using the system connected to a microscope, facilitated diffusion of oxygen in hemoglobin solutions was observed and analyzed in a position-sensitive way. The results confirmed its applicability to this study and gave information about the diffusion mechanism expressed by the empirical formula J = kY, where J is the flux of oxygen, Y is the oxygen saturation of hemoglobin, and k is a constant.

Colorimetry↗
PubMed1987

Induction of SOS functions in Escherichia coli and biosynthesis of nitrosamine in rabbits by nitrogen dioxide.

Nitrogen dioxide induced SOS functions in Salmonella typhimurium and Escherichia coli K-12 and was mutagenic in Escherichia coli WP2. When a rabbit was administered aminopyrine intravenously and administered nitrogen dioxide by inhalation, N-nitrosodimethylamine was detected in its blood. Analysis was conducted with 15N-nitrosodimethylamine as an internal standard by a combination of capillary gas chromatography and mass spectrometry. Accompanying administration of cystamine increased the blood concentration of N-nitrosodimethylamine in the rabbit, suggesting inhibition of its metabolism. Concurrent sulfur trioxide inhalation increased N-nitrosodimethylamine formation in the rabbit.

Aminopyrine↗
PubMed1986

Inhibition by amines indicates involvement of nitrogen dioxide in autocatalytic oxidation of oxyhemoglobin by nitrite.

Oxidation of oxyhemoglobin by nitrite is characterized by a lag period followed by an autocatalytic phase. The oxidation can be inhibited by the addition of morpholine, piperidine, triethanolamine or triethylamine (6 mM each). These amines are known to react with nitrogen dioxide to yield nitrosamine. Unexpectedly, aniline or aminopyrine (120 microM each) markedly inhibited the oxidation. These compounds, but not the other amines given above, inhibited the peroxide compound formation from methemoglobin and hydrogen peroxide. The results establish that, during the oxidation, the peroxide compound is generated and converts nitrite into nitrogen dioxide by its peroxidatic activity, resulting in an autocatalytic phase.

Amines↗
PubMed1986

Induction of SOS functions by nitrogen dioxide in Escherichia coli with different DNA-repair capacities.

The effect of gaseous nitrogen dioxide (NO2) on cytotoxicity, induction of synthesis of UmuC and RecA proteins, and mutagenesis was studied in Escherichia coli strains with different capacities of DNA repair. Gaseous NO2 (90, 180 microliter/l) killed Escherichia coli. The recA mutant was most sensitive, the lexA mutant moderately sensitive, and the uvrA mutant and the wild-type the least sensitive. When 90 microliter/l NO2 gas was bubbled into bacterial suspensions for 30 min at a flow rate of 100 ml/min, the induction of umuC gene expression increased in the wild-type strain. NO2 also induced the recA gene expression in the wild-type strain. The synthesis of neither RecA nor UmuC proteins was induced in the recA and lexA mutants. We further investigated the NO2 mutagenesis in the cells treated with bubbling of NO2 gas. NO2 caused mutation to Trp+ of WP2.

DNA Repair↗
PubMed1985

Induction of umuC gene expression by nitrogen dioxide in Salmonella typhimurium.

Gaseous nitrogen dioxide (NO2) was found to induce umuC gene expression in Salmonella typhimurium carrying the umuC-lacZ fusion plasmid. The induction level of the umu operon responsible for inducible mutagenesis was measured by the level of beta-galactosidase in the cell, encoded by the fusion gene. NO2 gas was bubbled into bacterial suspensions at 10, 30 and 90 microliters/l for 30 min at a flow rate of 100 ml/min. Expression of the umuC gene varied with the concentration, flow rate and bubbling time of the NO2 gas. Although NO2 gas induces SOS functions, mutagenesis due to it was not detectable in Salmonella typhimurium TA100 and TA102. Nitric oxide gas (NO) did not induce any umuC gene expression.

DNA Repair↗
PubMedDate not supplied

Induction of sister-chromatid exchanges by N-nitrosocimetidine in cultured human lymphocytes and its inhibition by chemical compounds.

The effect of nitrosocimetidine (NC) on the frequency of sister-chromatid exchanges (SCEs) in human lymphocytes has been studied. The frequency of SCEs induced by a 1-h exposure to 2.6 X 10(-4) M NC was 4-fold greater than that in the solvent control. A 72-h exposure to NC had a similar dose-related effect. We also examined the effect of the sulfhydryl compounds cysteine, cysteamine, cystamine and glutathione, the reducing agent dithionite, and vitamins C and E on the NC-induced SCEs. None of these compounds induced SCEs. Cysteine, cysteamine, and cystamine significantly reduced the number of NC-induced SCEs, and the others did not.

Ascorbic Acid↗