Level Of metHb Research Articles

Transcutaneous evaluation of hemoconcentration response to hypoxia simulated and hypobaric hypoxia of 5050 m

Objective: To evaluate the effect of normobaric and hypobaric hypoxia of 5050 m on hemoconcentration response in population without experience to hypoxia and acclimatized population to chronic intermittent hypobaric hypoxia (CIHH). Materials and Methods: 16 subjects without experience to altitudes over 1500 m (9 women/7 men) and 39 subjects acclimatized workers to CIHH at high altitude (5050 m, 9 women/32 men) were recruited. Normobaric hypoxia were performed in 3 steps: 5 min breathing ambient air, 20 min breathing hypoxic air (11,5% O2, equivalent to 5050 m) and 5 min of recovery breathing ambient air. CIHH condition represents a normal exposure characterized by 8 days working at high altitude and 6 days resting at low altitude (<1500 m). Subjects were evaluated at sea level and 5-6th day of exposure to CIHH at 5050 m. In each condition, Hemoglobin concentration (Hb), Carboxyhemoglobin (COHb), Methemoglobin (MetHb), Pulse oximetry (SPO2), heart rate (HR) were measured using a transcutaneous sensor (Rad 67 pulse Co-Oximeter, Masimo). Results: In evaluations performed at sea level, both groups of hypoxia (normobaric and CIHH) exhibited a lower hemoglobin concentration in women in comparison with men. During exposure to simulated hypoxia, a significative increase in hemoglobin concentration was showed, associated to decrease in SpO2 and increase in HR. However, an increased level of MetHb in women and men and only increased level of COHb in women were observed. During hypobaric exposure, Hb concentration increased, with reduced SpO2, and increased HR in comparison to sea level. Lower HR was observed in men respect of women. Lower level of COHb was observed in men respect of women. In addition, in women was observed an increase of level COHb related with time of exposure, in contrast, a tendency to reduction in level of COHb and MetHb in men was observed. Conclusion: The use of transcutaneous sensor to measure SpO2 and Hb showed an increase in hemoglobin concentration in normobaric and hypobaric hypoxia, in agreement with previous results from our laboratory. In addition, we reported new information about level of COHb and MetHb in two different model of exposure simulated hypoxia and hypobaric hypoxia at extreme altitude. SUSESO ACHS 279-2022. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

التغيرات الدموية في مستويات الهيموغلوبين و المتهيموغلوبين بعد التسمم بالنترات في دجاج اللحم

This study was aimed to understand the hematological changes in the level of Hb and Met-Hb which produced after potassium nitrate intake via water and feed to broiler chicks for 6 weeks and indifferent concentration also after stoppage for 4 weeks of nitrate intake. 
 A number of 135 chicks one day old faobro breed were used. After two weeks aclimitiztiation ,chicks were separated in to seven groups , one was control and other six were given potassium nitrate in drinking water or in feed at 0.25, 0.5, 0.75 gm/ kg body weigh to each group. 
 The results showed significant statistical in the Hb rates and the different nitrate concentrations used. Also there were significant differences in the 2nd week of the experiment and indicated a decrease in Hb concentrations. Statistical significant of difference was obvious in the groups fed on concentrations 0.25, 0.5 gm/ kg b.w. and in groups given nitrate in drinking water in concentrations 0.25, 0.5, 0.75 gm/kg b.w. 
 There were significant statistical differences in Met-Hb rates formed and the amount of nitrate used and the weeks in all animal groups treated with nitrate which started at the 3rd week from the start of the experiment. 
 The increase in the rates of Met-Hb indicate an important statistical differences or significances especially in groups fed 0.25 gm/kg b.w. nitrate concentration and in drinking water groups at 0.5 and 0.75 gm/kg b.w. concentrations. no significant statistical differences between the control group from week 8th till the week 10th of the experiment.

Relationship between effects of riociguat and levels of methemoglobin in patients with chronic thromboembolic pulmonary hypertension

Abstract Background Soluble guanyl cyclase (sGC) is a receptor for nitric oxide (NO) and plays an important role in vascular tonus. sGC stimulant is a therapeutic agent for pulmonary hypertension and an advantage of sGC stimulant over phosphodiesterase (PDE)-5 inhibitors is that sGC stimulant exerts its effect even when NO production is reduced. NO derived from vascular endothelial cells is immediately absorbed by hemoglobin (Hb), which leads to the production of methemoglobin (Met-Hb) when oxidized. Previous report has shown that the therapeutic effect of PDE-5 inhibitors was associated with levels of Met-Hb. Purpose In this study, we examined the relationship between the effect of riociguat and levels of Met-Hb in patients with chronic thromboembolic pulmonary hypertension (CTEPH). Methods The study population comprised 18 patients with CTEPH. Mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) were assessed before and after administration of riociguat, and changes in mPAP and PVR were defined as ΔmPAP and ΔPVR, respectively. Since the level of Met-Hb was obtained as the percentage of Hb (FMet-Hb), the amount of Met-Hb was calculated by following formula: Met-Hb (mg/dL) = Hb (g/dL) × FMet-Hb (%) × 10. Results The amount of Met-Hb value before administration of riociguat was significantly correlated with the degree of improvement in mPAP and PVR after administration of riocigat (R=−0.502, P<0.05 mPAP; R=−0.481, P<0.05 PVR, respectively) as shown in figures. Conclusion Our findings suggest that the level of Met-Hb before treatment may predict the therapeutic effect of sGC stimulants in patients with CTEPH. Funding Acknowledgement Type of funding source: None

In vivo evaluation of electron mediators for the reduction of methemoglobin encapsulated in liposomes using electron energies produced by red blood cell glycolysis

Earlier studies have clarified that NADH and NADPH, re-energized repeatedly by red blood cell (RBC) glycolysis, can be used in extracellular chemical reactions, where electron energies are extracted by electron mediators, such as methylene blue (MB). The electron mediators, which are reduced by NAD(P)H, permeate both the membranes of RBC and phospholipid bilayer of liposomes encapsulating haemoglobin (Hb-vesicles, HbV) and reduce autoxidized ferric methemoglobin (metHb) in HbV to ferrous Hb. Moreover, in vitro screening study clarified some other potential electron mediators with comparable capacity to reduce metHb. Given this background, eight of these compounds: MB, 1,9-dimethyl MB, azure A, azure B (AB), azure, toluidine blue, brilliant cresyl blue and toluylene blue, were evaluated in both in vitro and in vivo studies in this work. Compared with MB as a reference, in vitro experiments demonstrated that most compounds caused effective metHb reduction of HbV in the presence of RBC. However, in vivo experiments of bolus injection of autoxidized HbV to rats (10 mL HbV/kg body weight) followed by injection of the dye (1.53 mL/kg body weight, 2.6 mM) led to some differences from in vitro results. Effective metHb reduction was found for the combination of AB. To evaluate AB effectiveness further, a haemorrhagic shock and resuscitation model was used, where the rats were resuscitated with HbV. When the level of metHb increased to 50%, a dye solution was injected. Again, AB caused sufficient reduction of metHb. Through these in vivo experiments, this study clarified that AB is a suitable electron mediator to prolong the functional lifetime of HbV.

Hidden Antioxidative Functions of Reduced Nicotinamide Adenine Dinucleotide Coexisting with Hemoglobin.

Ferrous oxyhemoglobin (HbO2) in red blood cells (RBCs) invariably and slowly autoxidizes to form ferric methemoglobin (metHb). However, the level of metHb is always maintained below 0.5% by intracellular metHb reduction of enzymatic systems with coenzymes, such as reduced nicotinamide adenine dinucleotide (NADH), and by superoxide dismutase (SOD) and catalase (CAT), which eliminate reactive oxygen species. Unquestionably, NADH cannot reduce metHb without the corresponding enzymatic system. Our study, however, demonstrated that a high concentration of NADH (100-fold of normal level, equimolar to HbO2) retarded autoxidation of HbO2 in a highly purified Hb solution with no enzymatic system. Furthermore, an inhibitory effect of NADH on metHb formation was observed with additions of oxidants such as H2O2, NO, and NaNO2. Our mechanism assessment elucidated extremely high pseudo-CAT and pseudo-SOD activities of NADH with coexistence of HbO2, and reactivity of NADH with NO. We prepared a model of RBCs (Hb-vesicles, Hb-V) encapsulating purified HbO2 solution and NADH, but no enzymatic system within liposome. We confirmed the inhibitory effect of NADH on both autoxidation and oxidant-induced metHb formation. In addition, an intravenous administration of these Hb-Vs to rats caused significant retardation of metHb formation by approximately 50% compared to the case without NADH coencapsulation. Based on these results, we elucidated a new role of NADH, that is, antioxidative effect via interaction with Hb, in addition to its classical role as a coenzyme.

The Protective Effect of Radish (Raphanus sativus) Seeds Against the Oxidative Stress Induced by Sodium Nitrite in Male Rabbits (Oryctolagus cuniculus)

The aim of this study is to investigate the protective effect of Radish (Raphanus sativus) seed alcoholic extract 70% against oxidative stress induced by sodium nitrite NaNO2 Twenty five adult male rabbits were devided into five groups of (five rabbits in each group) and treated daily for 30 days. Group T1: intubated orally 20 mg/kg NaNO2, Group T2: intubated orally 20 mg/kg NaNO2 + 50 mg/kg of alcoholic extract from Raphanus sativus seeds, Group T3: intubated orally 20 mg/kg NaNO2 + 100 mg/kg of alcoholic extract from Raphanus sativus seeds, Group T4: intubated orally 20 mg/kg NaNO2 + 200 mg/kg of alcoholic extract from Raphanus sativus seed as well as Group C: control intubated orally distilled water. In comparison with normal rabbits there were significantly increase in the level of Methemoglobin (MetHb%) , lipid peroxidation indicator malondialdehyde (MDA), and significantly decrease in the level of glutathione (GSH) in the rabbits intubated NaNO2. In rabbits intubated NaNO2 + 50,100,200 mg/kg of alcoholic extract it was found there were significant decreased in the level of MetHb%, MDA, and increase in the level of GSH. In conclusion according to results obtained from this study approved that alcoholic extract of Raphanus sativus seeds in dose (50,100,200 mg/kg) have protective effect against oxidative stress induced by sodium nitrite in male rabbits.

The Protective Effect of Radish (Raphanus sativus) Seeds Against the Oxidative Stress Induced by Sodium Nitrite in Male Rabbits (Oryctolagus cuniculus)

The aim of this study is to investigate the protective effect of Radish (Raphanus sativus) seed alcoholic extract 70% against oxidative stress induced by sodium nitrite NaNO2 Twenty five adult male rabbits were devided into five groups of (five rabbits in each group) and treated daily for 30 days. Group T1: intubated orally 20 mg/kg NaNO2, Group T2: intubated orally 20 mg/kg NaNO2 + 50 mg/kg of alcoholic extract from Raphanus sativus seeds, Group T3: intubated orally 20 mg/kg NaNO2 + 100 mg/kg of alcoholic extract from Raphanus sativus seeds, Group T4: intubated orally 20 mg/kg NaNO2 + 200 mg/kg of alcoholic extract from Raphanus sativus seed as well as Group C: control intubated orally distilled water. In comparison with normal rabbits there were significantly increase in the level of Methemoglobin (MetHb%) , lipid peroxidation indicator malondialdehyde (MDA), and significantly decrease in the level of glutathione (GSH) in the rabbits intubated NaNO2. In rabbits intubated NaNO2 + 50,100,200 mg/kg of alcoholic extract it was found there were significant decreased in the level of MetHb%, MDA, and increase in the level of GSH. In conclusion according to results obtained from this study approved that alcoholic extract of Raphanus sativus seeds in dose (50,100,200 mg/kg) have protective effect against oxidative stress induced by sodium nitrite in male rabbits.

Red blood cells donate electrons to methylene blue mediated chemical reduction of methemoglobin compartmentalized in liposomes in blood.

Electron-energy-rich coenzymes in cells, NADH and NADPH, are re-energized repeatedly through the Embden-Meyerhof and pentose-phosphate glycolytic pathways, respectively. This study demonstrates extraction of their electron energies in red blood cells (RBCs) for in vivo extracellular chemical reactions using an electron mediator shuttling across the biomembrane. Hemoglobin-vesicles (HbVs) are an artificial oxygen carrier encapsulating purified and concentrated Hb solution in liposomes. Because of the absence of a metHb-reducing enzymatic system in HbV, HbO2 gradually autoxidizes to form metHb. Wistar rats received HbV suspension (10 mL/kg body weight) intravenously. At the metHb level of around 50%, methylene blue [MB(+); 3,7-bis(dimethylamino)phenothiazinium chloride] was injected. The level of metHb quickly decreased to around 16% in 40 min, remaining for more than 5 h. In vitro mixing of HbV/MB(+) with RBCs recreated the in vivo metHb reduction, but not with plasma. NAD(P)H levels in RBCs decreased after metHb reduction. The addition of glucose facilitated metHb reduction. Liposome-encapsulated NAD(P)H, a model of RBC, reduced metHb in HbV in the presence of MB(+). These results indicate that (i) NAD(P)H in RBCs reacts with MB(+) to convert it to leukomethylene blue (MBH); (ii) MB(+) and MBH shuttle freely between RBC and HbV across the hydrophobic lipid membranes; and (iii) MBH is transferred into HbV and reduces metHb in HbV. Four other electron mediators with appropriate redox potentials appeared to be as effective as MB(+) was, indicating the possibility for further optimization of electron mediators. We established an indirect enzymatic metHb reducing system for HbV using unlimited endogenous electrons created in RBCs in combination with an effective electron mediator that prolongs the functional lifespan of HbV in blood circulation.

Late Diagnosis of Congenital Methemoglobinemia in an Elderly Patient During Cardiac Surgery

METHEMOGLOBIN (metHb), resulting from the oxidation of iron in hemoglobin from the ferrous state to ferric state, cannot bind oxygen and thereby leads to a displacement of the hemoglobin dissociation curve to the left. It can, therefore, impair tissue oxygen delivery. Methemoglobinemia, which is characterized by the presence of a higher-than-normal level of metHb, either can be congenital (due to Hb variants or deficiency of enzymes that convert metHb back to Hb) or acquired (caused by drugs or toxins 1 Trapp L. Will J. Acquired methemoglobinemia revisited. Dent Clin North Am. 2010; 54: 665-675 Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar , 2 Umbreit J. Methemoglobin—It's not just blue: A concise review. Am J Hematol. 2007; 82: 134-144 Crossref PubMed Scopus (251) Google Scholar ).

ROS production and their influence on the cellular antioxidative system in human erythrocytes incubated with daunorubicin and glutaraldehyde

This study examined the effects of daunorubicin and glutaraldehyde on some parameters of erythrocytes. The aim of the article was to present the results of research aiming to identify the level of glutaraldehyde at which the hemoglobin oxidation, externalization of phosphatidylserine and the changes in the viability (hemolysis) of erythrocytes are not statistically significant and therefore this level of glutaraldehyde can be used for the drug carriers’ preparation. Glutaraldehyde was used as a crosslinking agent to enhance the uptake of the drug within red blood cells and to prevent its leakage from the cells. Fluorescence microscopy, flow cytometry and fluorimetric measurements confirmed higher levels of the drug in glutaraldehyde-treated human erythrocytes. Unfortunately, substantial damage to the red blood cells was also noted. DNR increased oxidative processes in the cell, which in turn led to an increase in the reactive oxygen species (ROS) level. When the red blood cells were also treated with glutaraldehyde, ROS production was significantly higher. We also observed loss of both the reduced and the total glutathione. Moreover the decreased activity of glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD) was also observed. As hemoglobin, the erythrocytes’ main component plays an essential role in the erythrocytes, the level of its oxidized form (metHb) in the erythrocytes and the phosphatidylserine exposure on the erythrocyte surface were also investigated. When higher concentrations of glutaraldehyde (0.0025–0.005%) were used for the uptake of DNR the elevated level of metHb was observed. Only at 0.0005% the level of oxidized form of Hb was within the physiological level and at that level the increase in the exposure of phosphatidylserine at the cell surface was not observed to be statistically significant. Moreover the percent of released hemoglobin was less than 1%.Based on these results it was concluded that glutaraldehyde can be used as a cross-linker between the drug (DNR) and the erythrocytes only at low concentration of about 0.0005%.

The effect of bromfenvinphos and its impurities on human erythrocyte

Bromfenvinphos – (E,Z)-O,O-diethyl-O-[1-(2,4-dichlorophenyl)-2-bromovinyl] phosphate (BFVF) is the insecticide elaborated in Poland, which has been used against Varroa destructor causing honey bees disease called as varroosis. The substances that are formed as a result of bromfenvinphos synthesis are dihydro-bromfenvinphos (O,O-diethyl O-[1-(2,4-dichlorophenyl)vinyl] phosphate); dibromo-bromfenvinphos (O,O-diethyl O-[1-(2,4-dichlorophenyl)-2,2-dibromovinyl] phosphate); 2,4-dichlorophenacyl bromide; 2,4-dichlorophenacylidene bromide and 2,4-dichlorophenacylidyne bromide.In this work, we evaluated the effect of these compounds on hemolysis and hemoglobin oxidation (met-Hb formation) in human erythrocytes. Moreover, the changes in the size (FSC-A) and the shape (SSC-A) of red blood cells were assessed using flow cytometry and phase contrast microscopy.It was proven that bromfenvinphos at concentrations ranging from 0.5 to 250μM during 1h incubation did not change the parameters examined in human erythrocytes. Similarly, most of bromfenvinphos impurities did not increase hemolysis and methemoglobin level nor changed the size and shape of the erythrocytes. The exception was dibromo-bromfenvinphos, which changed the FSC-A and SSC-A parameters, as well as 2,4-dichlorophenacyl bromide which induced hemolysis, increased the level of met-Hb and changed erythrocytes morphology.

Blood Levels of Methemoglobin in Patients with Aluminum Phosphide Poisoning and its Correlation with Patient’s Outcome

Although methemoglobinemia following aluminum phosphide (AlP) intoxication has been reported, probable effect of blood level of methemoglobin (Met-Hb) on outcome of AlP-poisoned patients has not yet been investigated. This study aimed to evaluate blood levels of methemoglobin in patients with AP intoxication and its correlation with patient's outcome. This prospective study was carried out at the Loghman-Hakim poison hospital from April 2009 to August 2009. All patients aged >12 years who had ingested AlP and were admitted at the hospital were enrolled in the study. Using the co-oximetry, blood Met-Hb level was measured at the time of admission and 24 h later if the patient survived. Forty-eight patients with AlP intoxication including 24 males were evaluated. Mean age of the patients was 25.5±9.5 years. There was significant association between blood level of Met-Hb at the time of admission and mortality (2.4%±7.1% in survivors versus 15.2%±13.5% in non-survivors, P<0.001). The same association was found at the 2nd day of admission (2.9%±8.2% in survivors versus 26.5%±9.9% in non-survivors, P=0.02). The present study found an association between blood level of Met-Hb and mortality in patients with AlP intoxication. Effect of administration of vitamin C and methylene blue on outcome of patients with AlP intoxication should be investigated in future studies.

Simulation study of methemoglobin reduction in erythrocytes

Methemoglobin (metHb), an oxidized form of hemoglobin, is unable to bind and carry oxygen. Erythrocytes are continuously subjected to oxidative stress and nitrite exposure, which results in the spontaneous formation of metHb. To avoid the accumulation of metHb, reductive pathways mediated by cytochrome b5 or flavin, coupled with NADH-dependent or NADPH-dependent metHb reductases, respectively, keep the level of metHb in erythrocytes at less than 1% of the total hemoglobin under normal conditions. In this work, a mathematical model has been developed to quantitatively assess the relative contributions of the two major metHb-reducing pathways, taking into consideration the supply of NADH and NADPH from central energy metabolism. The results of the simulation experiments suggest that these pathways have different roles in the reduction of metHb; one has a high response rate to hemoglobin oxidation with a limited reducing flux, and the other has a low response rate with a high capacity flux. On the basis of the results of our model, under normal oxidative conditions, the NADPH-dependent system, the physiological role of which to date has been unclear, is predicted to be responsible for most of the reduction of metHb. In contrast, the cytochrome b5-NADH pathway becomes dominant under conditions of excess metHb accumulation, only after the capacity of the flavin-NADPH pathway has reached its limit. We discuss the potential implications of a system designed with two metHb-reducing pathways in human erythrocytes.

Radiation damage to human erythrocytes: Influence of the composition of medium

The erythrocyte suspensions in PBS (Na-phosphate buffered isotonic NaCl solution) or PB (Na-phosphate isotonic buffer) (hematocrit 1%) were irradiated with the dose of 400 Gy in aerobic conditions. The level of damage to cells was estimated after incubation in different media. A higher level of destruction of cells irradiated in PBS than in PB was observed. The same level of MetHb and lipid peroxidation determined right after irradiation was detected. However, the loss of reduced glutathione was higher in PB than in PBS. We discussed the contribution of hydroxyl and chloride radicals in the initiation of erythrocyte damage.

Does cholesterol bound to haemoglobin affect the anti-oxidant enzyme defence system in human erythrocytes?

In a previous study, it was shown that the lipid fraction, which is occasionally observed in red blood cell hemolysates, represents cholesterol (Ch) associated with phospholipid firmly bound to haemoglobin (termed Hb-Ch). The current study was conducted to investigate whether Hb-Ch could affect the primary anti-oxidant enzyme defence system in human erythrocytes. Sixty healthy volunteers were used for the current study. Group 1 consisted of 28 subjects without or with a low level of Hb-Ch. Group 2 comprised 32 subjects with a considerably higher level of Hb-Ch. The activities of erythrocyte superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, as well as the content of methaemoglobin (metHb) were measured in both groups. The results indicated that the amount of Hb-Ch neither influenced the activities of the erythrocyte anti-oxidant enzymes nor altered the level of metHb. However, a higher amount of Hb-Ch changed the correlations in the part of the anti-oxidant defence system relating to glutathione, suggesting increased peroxidative pressure from plasma lipids. Group 2 also had significantly increased concentrations of total plasma Ch and triglycerides. Together, these facts are strong indications that the anti-oxidant defence system in human erythrocytes finely retunes its composition according to plasma oxidative demands. .

Photoreactivity of chloramphenicol in vitro and in vivo.

The negative side effects of chloramphenicol (CAP) mostly involve blood dyscrasias (e.g. irreversible non-dose-dependent aplastic anemia), allergic skin reactions and eye damage. To learn the cause of these side effects, most research focuses on metabolically formed nitroso- and hydroxylamino derivatives in the predisposed patient. In previous investigations it was demonstrated that photochemical decomposition of CAP in vitro by UV-A leads to formation of p-nitrobenzaldehyde (pNB), p-nitrobenzoic acid (pNBA) and p-nitrosobenzoic acid (pNOBA); the latter comprises up to 45 mol% of the starting amount of CAP. Incubation of these photoproducts in rat blood showed that pNB and pNOBA rapidly react and that PNBA is stable under these conditions. Reaction products from pNB (half-life 1.7 min) proved to be pNBA and p-nitrobenzyl alcohol (pNBOH) while pNOBA (half-life 3.7 min) was converted into p-aminobenzoic acid (pABA). Exposure of CAP in rat blood to UV-A yielded the same end products: pNBA, pABA and pNBOH. To estimate the amount of oxidative stress generated in vivo by these compounds, the ability to form methemoglobin (MetHb) in erythrocytes was tested; only pNOBA and p-hydroxylaminobenzoic acid (pHABA), a possible intermediate in the decomposition of pNOBA, proved to be reactive. Ultraviolet-A exposure of rats, after intraperitoneal injection of CAP, led to 3.6 times the basic level of MetHb. In addition, covalent binding of 3H-labeled CAP photoproducts to the skin of the back and to the ears was found, which was 9.1 and 3.2 times higher, respectively, than the dark values.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxidative damage of red blood cells in haemolytic uraemic syndrome

Changes in red blood cell (RBC) lipid peroxidation [measured by malonyl dialdehyde (MDA) concentration], glutathione (GSH) metabolism, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase) and haemoglobin (Hb) metabolites (metHb, carboxy Hb) were studied in six children with post-enteropathic (D+) haemolytic uraemic syndrome (HUS) and ten controls. The in vitro effect of hydrogen peroxide [acetylphenylhydrazine (APH) test] on GSH and Hb metabolism was also investigated. MDA levels were significantly higher and the antioxidant enzyme activities were lower in HUS patients than in the controls (P < 0.01). The oxidised glutathione concentration was significantly higher in the patients than in the control children (26.3 +/- 12.6 vs. 10.9 +/- 1.8 nmol/g Hb. Percentage values of carboxy Hb and metHb were also higher in HUS (P < 0.01). Incubation of RBC with APH induced a more pronounced decrease in the concentration of GSH (P < 0.001) and a significant increase (P < 0.01) in the level of metHb and carboxy Hb in the HUS patients. This suggests that there is reduced RBC GSH stability in HUS. Utilisation of GSH and antioxidant enzymes leads to increased Hb oxidation and haemolysis. The oxidative damage may have an important role in the pathogenesis of haemolytic anaemia in HUS.

The role of catalase in protecting erythrocytes against methemoglobin formation.

Some mechanisms to reduce methemoglobin (metHb) formation for the maintenance of normal oxygen transport have been proposed. To study the role of catalase (EC 1.11.1.6), metHb formation in the hemolysate of normal and Japanese acatalasemic human subjects were examined spectrophotometrically. Significantly increased level of metHb was induced by potassium ferrocyanide in the hemolysate of acatalasemic subject. The addition of catalase reduced the metHb formation, while 3-amino-1,2,4-triazole (AT), a specific inhibitor of catalase-H2O2 compound I, increased it. These results obtained from human subjects were well consistent with those from mice and suggested that catalase plays a role in protecting erythrocytes against metHb formation.

Low levels effect of nitrogen oxides emitted by power station

Abstract In some people exposed to the long‐lasting activity of compounds contained in the “ chimney trail “ of power station the increasel level of MetHb was found but no increased values of SHb were observed Human organism responds to low concentrations of nitrogen oxides contained in the atmosphere by reaction to increased level of MetHb as well as the increase of GSH concentration in erythro‐cytes found near the upper limits of norm, and the increase of activity of G‐6‐PD and first of all the activity of MetHb‐Red. In the examined cases the Hb moleculary structure was of A type≪ The mechanism of human organism's response to the low concentrations of nitrogen oxides in inhaled air may be examined in two aspects, namely as the subtoxic effect with the increase of MetHb and as hormetic activity, stimulating the increase of reduction system activity.

Monoamine Oxidaseに関する研究第23報

The effects on Monoamine Oxidase (MAO) in rat brain and liver and production of methemoglobin (Met-Hb) in blood by the administration of NaNO2 and NH2OH have been studied and the following results were obtained : Administration of NaNO2 and NH2OH caused a marked increase in the blood level of Met-Hb. Met-Hb in blood was 6.4 and 4.5 g/dl after i. p. administration of 100mg/kg NaNO2 and NH2OH, respectively. The blood level of Met-Hb reached a maximum at 15 and 30min following i. p. administration of 50mg/kg NaNO2 and NH2OH, respectively and then disappered gradually. Rats were administered NaNO2 i. p. in a dose of 50mg/kg/day for 30 days. The blood level of Met-Hb was increased slightly on the 3rd-4th day. The increasing MAO activity in rat liver was observed immediately and on the 2nd day following i. p. administration of 50mg/kg NaNO2 when tyramine was used as substrate. When benzylamine was used as substrate, MAO activity increased at 2-3 hours and on the 4th day. MAO activity in rat brain markedly increased on the 3 rd-4th day following i. p. administration of NaNO2 with tyramine as substrate. Similar results were obtained when serotonin (5-HT) was used as substrate. Rats were administered NH2OH i. p. in a dose of 50mg/kg/day for 30 days. The blood level of Met-Hb was increased slightly on the 3rd-4 th day. When tyramine was used as substrate, increasing MAO activity was observed on the 5th day of administration. Significant change of MAO activity was not observed when benzylamine was used as substrate. In case of brain, MAO activity increased on the 4th-6th day and decreased 1st-2nd day and 14th-20th day of administration when tyramine was used as substrate. Almost similar results were obtained when 5-HT was used as substrate.