钼对克山病病区粮养大鼠红细胞NADH—细胞色素b5高铁血红蛋白还…

Ｗｉｓｔａｒ大鼠３０只，雌雄各半分层均匀分为非病区粮组、病区粮组和病区粮补钼组（１００ｍｇ／ｋｇ），分别喂以克山病非病区粮和克山病病区粮，实验期为４个月。病区粮养大鼠红细胞还原高铁血红蛋白的能力，ＮＡＤＨ－细胞色素ｂ５高铁血红蛋白还原酶活力均低于非病区粮组。病区粮补钼可升高此酶活力，提高红细胞还原高铁血红蛋白的能力，在一次失血的应激情况下，程度达到显著。病区粮补钼（１００ｍｇ／ｋｇ）对红细胞谷胱甘     

钼对缺硒大鼠心肌线粒体功能的影响

本文以克山病病区粮喂养大白鼠造成缺硒动物模型，以病区粮加钼作为处理因素，对大鼠心肌线粒体ＳＤＨ，ＣＣＯ活力及氧化磷酸化效率（Ｐ／Ｏ比值）做了测定。结果显示，钼对上述测定指标均有不同程度的改善，大剂量钼（４０ｍｇ／ｋｇ饲料）的作用优于小剂量钼（２．０ｍｇ／ｋｇ饲料），且与对照组相比有显著的统计学意义。此外，小剂量钼也能明显提高心肌线粒体ＳＤＨ活力。实验结果提示，改善心肌线粒体呼吸链功能及氧化磷酸化效     

克山病病区粮喂养大鼠红细胞NADH—高铁血红蛋白还原酶活性改变以及硒、维生素E、B_1对其活性的影响

应用黑龙江省尚志县克山病病区粮喂养大鼠4个月,观察到喂病区粮大鼠其红细胞NADH—高铁血红蛋白还原酶活性明显低于非病区粮喂养的大鼠;病区粮单纯补充硒对此酶影响不大,而病区粮同时补充硒和维生素E以及同时补充硒和维生素B_1均能明显提高其活性。病区粮喂养大鼠其高铁血红蛋白还原速率低于非病区粮喂养之大鼠。     

硒锗对克山病病区粮喂养大鼠心,肝,肾,脂质过氧化的影响

用克山病病区粮配制的低硒饲料，加入一定量的硒（Ｎａ２ＳｅＯ３，０．５５ｍｇ／ｋｇ）或／和（Ｇｅ－１３２，３００ｍｇ／ｋｇ），研究对病区粮喂养大鼠心、肝、肾脂质过氧化的影响。结果表明，病区粮喂养大鼠１２周，可致大鼠肝、肾自由基含量，心、肝、肾脂质过氧化物（ＬＰＯ）水平显著增加；心、肝、肾谷胱甘肽过氧化物酶（ＧＳＨ－Ｐｘ）活性显著降低。病区粮中补硒（ＮＭａ２ＳｅＯ３，０．５５ｍｇ／ｋｇ）可以拮抗低硒喂     

克山病致病因素对大鼠心肌线粒体α－磷酸甘油脱氢酶的影响

测定了克山病病区粮喂养大鼠心肌线粒体α－磷酸甘油脱氢酶（ａ－ＧＰＤ）活性，并观察了硒和维生素Ｅ对该酶的影响。结果表明，病区粮组大鼠心肌线粒体α－ＧＰＤ活力明显低于非病区粮组和常规．食组，并在补０．１μｇ／ｇ＋８００μｇ／ｇＶＥ后，α－ＧＰＤ活性升高与病区粮组比较有显著差异、本实验结果提示：１、饲克山病病区粮大鼠心肌线粒体α－ＧＰＤ活力的降低，此时的心肌可能处于甲状腺激素功能低下状态．２、硒（０．１μｇ／ｇ）＋维生素Ｅ（８００μｇ／ｇ）的补充可以升高该酶活性，改善甲状腺激素功能不足状态。     

硒锰对全血谷胱甘肽过氧化物酶活性影响的动态观察

本文用克山病病区粮，以及在病区粮基础上加硒（０．４ｍｇ／ｋｇ）、锰（１００ｍｇ／ｋｇ），喂养大鼠８周，对大鼠全血谷胱甘肽过氧化物酶（ＧＳＨ—Ｐｘ）活性进行动态观察，结果表明：病区粮和病区粮加锰饲料均可以使大鼠全血ＧＳＨ—Ｐｘ活性显著下降，加锰组下降的幅度更大；病区粮加硒使ＧＳＨ—Ｐｘ活性升高。相关分析表明：实验８周时．血硒浓度同ＧＳＨ—Ｐｘ活性呈显著正相关；血锰浓度与ＧＳＨ—Ｐｘ活性未见相关性。提示标通过对硒的作用来影响ＧＳＨ—Ｐｘ的活性，硒和锰之间存在相互作用。     

克山病红细胞膜中维生素E的分析

本文对饲克山病病区糖大鼠的克山病患者红细胞膜中维生素Ｅ（ＶＥ）进行了研究，结果表明：饲克山病病区粮大鼠红细胞膜中α－ＶＥ显著低于非病区粮组；病区粮补充α－ＶＥ后，大鼠红细胞膜中α－ＶＥ显著增加，α＋ｒ－ＶＥ也有所增加，ｒ－ＶＥ则下降；病区粮补硒后，α－ＶＥ，ｒ－ＶＥ均上升；克山病患者红细胞膜中α－ＶＥ、ｒ－ＶＥ均低于病区对照和非病区对照，而病区对照和非病区对照之间无显著性差异。     

克山病区粮养动物心肌T_45~′—脱单碘酶活力的改变及硒和维生素E对其保护作用的研究

本文测定了饲克山病区粮大鼠心肌T_45′—脱单碘酶活性,结果表明病区粮组动物心肌脱碘酶活力明显低于非病区粮组,并在补硒或维生素E后升高。提示心肌组织脱碘酶的损伤所致心肌组织甲状腺激素代谢改变在克山病心肌病变中可能起着重要的作用。     

硒和维生素E对克山病病区粮喂饲大鼠心肌损伤的影响

本实验在克山病病区粮食中补充硒和维生素E(VE)或单独补充硒喂饲大鼠,和单纯喂饲病区粮大鼠比较,联合补充硒和VE可明显减轻亚硝酸钠引起的大鼠心肌损伤;硒加VE组大鼠红细胞高铁血红蛋白还原酶活性明显升高,其可使亚硝酸盐氧化血红蛋白形成的高铁血红蛋白迅速还原,从而减轻机体缺氧状态;硒和VE可使大鼠心肌脂质过氧化产物丙二醛含量明显减少,减轻了病区粮喂饲大鼠心肌损伤;硒加VE使大鼠血清甲状腺激素(T_3、T_4)和心肌呼吸酶(CCO、SDH)活性维持在低水平,表明其纠正了病区粮喂养大鼠心肌能量代谢紊乱,使代偿增加的血清T_3、T_4和心肌CCO、SDH活性降低。和病区粮组大鼠比,单纯加硒组大鼠除心肌谷胱甘肽过氧化物酶活性升高外,其心肌损伤未明显减轻。 上述结果提示,联合补充硒和VE在预防克山病发病上可能会有更好效果。     

亚硝酸钠对饲克山病病区粮大鼠血液流变学影响

以低硒（Ｓｅ）低维生素Ｅ（ＶＥ）为克山病病区粮饲养大鼠１０周，用腹腔注射亚硝酸钠引起急性缺氧的方法，结果表明，病区粮组大鼠红细胞变形性，ＧＳＨ－Ｐｘ，Ｃｕ，Ｚｎ－ＳＯＤ活力降低，血清ＣＫ，ＬＰＯ含量增高，补Ｓｅ和ＶＥ可使上述变化逆转。结果提示，红细胞变形性，抗氧化能力和自由基代谢障碍，是亚硝酸钠与Ｓｅ和ＶＥ缺乏协同造成心肌损害的作用环节。     

Methemoglobinemia

The ferrous iron of hemoglobin is exposed continuously to high concentrations of oxygen and, thereby, is oxidized slowly to methemoglobin, a protein unable to carry oxygen. To restore hemoglobin function, methemoglobin (ferrihemoglobin) must be reduced to hemoglobin (ferrohemoglobin). Under physiological conditions, methemoglobin reduction is accomplished mainly by red cell NADH-cytochrome b₅ reductase (NADH-methemoglobin reductase) so efficiently that there is insignificant amounts of methemoglobin in the circulating blood. However, should methemoglobin formation be increased—e.g., due to the presence of oxidant drugs, or an abnormal methemoglobin not amenable to reduction (hemoglobin M), or a deficiency in red cell cytochrome b₅ reductase—methemoglobinemia will result. Most methemoglobinemias have no adverse clinical consequences and need not be treated. Under certain conditions, such as exposure to large amounts of oxidant or in young infants, rapid treatment is necessary. In hereditary cytochrome b₅ deficiency, treatment is often directed at improving the poor cosmetic effect of persistent cyanosis with the minimum amount of drugs to give satisfactory clinical results. © 1993 Wiley-Liss, Inc.     

Mechanism of isoproterenol induced myocardial damage

To study the harmful effects of isoproterenol on myocardium rats were injected with isoproterenol 10 or 0.1 mg.kg-1 or with isoproterenol 10 mg.kg-1 after an injection of propranolol 20 mg.kg-1. Endogenous phospholipase activity in heart homogenate and tissue adenosine triphosphate concentrations were determined 1, 7, and 15 h after isoproterenol injection. The activities of three segments (NADH-cytochrome c reductase, succinate-cytochrome c reductase, and cytochrome c oxidase) of the electron transport chain in heart mitochondria were also measured in the same manner. In the group given isoproterenol 0.1 mg.kg-1 the tissue adenosine triphosphate concentration was decreased after 1 h but returned to control value after 15 h. No significant change in phospholipase activity or in the activities of the three segments in mitochondria was observed throughout the study. In the group given isoproterenol 10 mg.kg-1 the tissue adenosine triphosphate concentration was significantly decreased after 1 h and did not return to control values after 15 h. Phospholipase activity was increased and the activities of NADH-cytochrome c reductase and cytochrome c oxidase were significantly decreased after 15 h. The activity of succinate-cytochrome c reductase was not affected. In the propranolol group, pretreatment with propranolol protected against a reduction in adenosine triphosphate after isoproterenol 10 mg.kg-1. Propranolol also prevented activation of phospholipase and maintained the activities of the three segments of mitochondria throughout the study. In an in vitro study mitochondria prepared from intact rat hearts were incubated with 0.1 unit phospholipase A2.(ABSTRACT TRUNCATED AT 250 WORDS)     

NADH-methemoglobin reductase and methemoglobinemia among leprosy patients

The NADH-methemoglobin reductase activity as well as hemoglobin and methemoglobin levels were investigated in blood samples of 182 adult leprosy patients and 137 Brazilian army enlisted men. The level of sulfones in the blood samples of the leprosy patients, all of them ingesting a daily dose of 100 mg dapsone, was also investigated. The mean value of NADH-methemoglobin reductase activity exhibited by the leprosy patients did not differ from that observed among the healthy individuals. However, the variance of the former group was significantly higher than that observed among the healthy subjects. As a consequence, the proportion of individuals showing a partial deficiency of NADH-methemoglobin reductase was significantly higher among the leprosy patients (22.5%) than among the healthy individuals (2.9%). The activity of this enzyme among the leprosy patients was negatively correlated to the hemoglobin level and slightly positively correlated to age. The concentration of methemoglobin among the leprosy patients was slightly but significantly higher as compared to the healthy individuals. The increase of the methemoglobin level among the leprosy patients was influenced by the amount of sulfones in the blood. However, no case in which dapsone was ingested in a daily dose of 100 mg presented the signs or symptoms of toxic methemoglobinemia.     

Coenzyme Q reductase from liver plasma membrane: purification and role in trans-plasma-membrane electron transport.

A specific requirement for coenzyme Q in the maintenance of trans-plasma-membrane redox activity is demonstrated. Extraction of coenzyme Q from membranes resulted in inhibition of NADH-ascorbate free radical reductase (trans electron transport), and addition of coenzyme Q10 restored the activity. NADH-cytochrome c oxidoreductase (cis electron transport) did not respond to the coenzyme Q status. Quinone analogs inhibited trans-plasma-membrane redox activity, and the inhibition was reversed by coenzyme Q. A 34-kDa coenzyme Q reductase (p34) has been purified from pig-liver plasma membranes. The isolated enzyme was sensitive to quinone-site inhibitors. p34 catalyzed the NADH-dependent reduction of coenzyme Q10 after reconstitution in phospholipid liposomes. When plasma membranes were supplemented with extra p34, NADH-ascorbate free radical reductase was activated but NADH-cytochrome c oxidoreductase was not. These results support the involvement of p34 as a source of electrons for the trans-plasma-membrane redox system oxidizing NADH and support coenzyme Q as an intermediate electron carrier between NADH and the external acceptor ascorbate free radical.     

Methemoglobinemia caused by the ingestion of courgette soup given in order to resolve constipation in two formula-fed infants

Methemoglobinemia is not a rare condition arising from the exposure to hemoglobin-oxidizing agents such as nitrates-nitrites present in well water or vegetables. Infants < 3 months of age are more susceptible than adults because of lower amounts of a key enzyme, NADH-cytochrome b5 reductase, which converts methemoglobin back to hemoglobin. We report 2 infants, aged respectively 2 and 1 months, suffering from methemoglobinemia, fed with a formula that was reconstituted with a high concentration of courgette soup to resolve constipation. They developed a severe cyanosis with methemoglobinemia (respectively 30.4 and 27%) and were hospitalized and treated with methylene blue at 1%. After 12 h the syndrome was completely resolved. Home-prepared infant foods containing vegetables are potential causes of methemoglobinemia. It is important not to feed infants with vegetables having a high nitrate content (e.g., courgette, spinach, beets and green beans) to resolve constipation since, particularly in the first months of life, they may cause severe methemoglobinemia.     

Differential Effect of Ethanol Consumption on Hamster Liver Microsomal Electron Transport Systems

The effect of 28-day ethanol consumption on hamster liver microsomal electron transport systems and associated enzymatic activities has been examined. Microsomes isolated from ethanol-consuming hamsters showed increased levels of cytochrome P-450 and NADPH supported enzymatic activities. In contrast, reductions in the amount of cytochrome b5 and the NADH-supported rate of stearoyl-CoA desaturase were observed. NADH-cytochrome c reductase was decreased while a small increase in NADH-ferricyanide reductase was observed. These data suggest that decreased stearoyl-CoA desaturase activity is the result of lowered cytochrome b5 levels in microsomes isolated from ethanol-consuming hamsters.     

The laboratory use of butylnitrite for the production of methemoglobin

The use of volatile butylnitrite in place of sodium nitrite for the in vitro production of methemoglobin was explored in studies of G6PD-deficient red cells and for measurements of the red cell methemoglobin reductase activity. It was found that butylnitrite vapor caused a more rapid oxidation of intracellular hemoglobin than sodium nitrite and required fewer washes for removal. Hence a more rapid preparation of the cells was possible. Both cytochemical detection of G6PD-deficient cells in a female heterozygote for G6PD deficiency and the screening test for a methemoglobin reductase deficiency could be performed with butylnitrite as well as with sodium nitrite. This small modification of these standard procedures promises to save time and facilitate processing of many samples during genetic screening of relevant populations.     

Methemoglobin Reduction: Studies of the Interaction between Cell Populations and of the Role of Methylene Blue

1. It has been shown that mixtures of normal and G-6-PD deficient nitrite-treated erythrocytes reduced methemoglobin at a rate considerably morerapid than that computed from their individual rates of methemoglobin reduction.

2. Differential agglutination studies demonstrated that when normal,methemoglobin-containing cells in such a mixture have reduced all of theirmethemoglobin, they facilitate methemoglobin reduction in G-6-PD deficienterythrocytes.

3. The same effect could be observed in other mixtures of cells, (e.g., normal with normal, G-6-PD deficient with G-6-PD deficient, etc.) and evenwith highly purified methemoglobin solutions.

4. This effect could be observed in the presence of methylene blue but notin the presence of another redox dye, Nile blue sulfate.

5. Lactate served as an effective substrate for methemoglobin reduction.Methemoglobin reduction by lactate was enhanced by methylene blue butnot by Nile blue sulfate.

6. In mixtures of normal and G-6-PD deficient erythrocytes, no deficit inthe rate of accumulation of lactate was found. This indicates that the mechanism of enhancement of methemoglobin reduction is not the diffusion oflactate from non-methemoglobin-containing cells to methemoglobin-containing cells.

7. It was demonstrated that leukomethylene blue could reduce highlypurified solutions of methemoglobin in the absence of the enzyme "methemoglobin reductase."

8. The possible mechanism by which non-methemoglobin-containing cellsmay reduce methemoglobin in methemoglobin-containing cells is discussed.It seems most probable that leukomethylene blue is the mediator of the effect.This implies, contrary to earlier suggestions, that "methemoglobin reductase"acts prior to the reduction of methylene blue in the electron transport chain.

Submitted on February 13, 1963 Accepted on April 3, 1963     

Methemoglobinemia associated with loxoscelism

In twenty five patients who presented the cutaneous form of loxoscelism, serum haptoglobin and lactic dehydrogenase, erythrocyte glucose-6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, methemoglobin, bilirubin and reticulocytes were investigated after bite. No hemolysis was detected but an increase in methemoglobin was found in 54% of the cases; in 7% it was between 1.1% and 2%, in 27% it ranged from 2.1% to 4%, and in 20% from 4.1% to 8%. Blood samples of a normal, blood group 0 individual and of a patient who exhibited methemoglobinemia after Loxosceles bite were incubated separately with antisera against Loxosceles gaucho, Crotalus terrificus, Bothrops jararaca, with Loxosceles gaucho venom and 0.3% phenol. No methemoglobin was found after 1, 4, 8 and 15 days in both sets of samples. At the 25th day all the samples, including the controls, exhibited similar methemoglobin reductase decrease. The data suggest that the methemoglobinemia which occurs in 50% of the patients probably arises from in vivo venom metabolism, inasmuch as the crude venom does not induce methemoglobinemia.     

Evidence that NADPH-dependent methemoglobin reductase and administered riboflavin protect tissues from oxidative injury

NADPH-dependent methemoglobin reductase, first detected in erythrocytes sixty years ago, has subsequently been purified and characterized as a methylene blue reductase and a flavin reductase. The reductase plays no role in methemoglobin reduction under normal conditions, but its activity serves as the basis for the treatment of methemoglobinemia with methylene blue or flavin. On-going studies demonstrate that this cytosolic protein is also present in liver and that its primary structure distinguishes it from other known proteins. The bovine erythrocyte reductase tightly binds hemes, porphyrins, and fatty acids with resulting loss of activity. Pyrroloquinoline quinone serves as a high-affinity substrate of the reductase, suggesting that this naturally-occurring compound may be a physiological substrate. The ability of the reductase to catalyze the intracellular reduction of administered riboflavin to dihydroriboflavin suggested that this system might be exploited to protect tissues from oxidative damage. This hypothesis was supported by our finding that dihydroriboflavin reacts rapidly with Fe(IV)O and Fe(V)O oxidation states of hemeproteins, states that have been implicated in tissue damage associated with ischemia and reperfusion. Preliminary studies demonstrate that, as predicted, administration of low concentrations of riboflavin protects isolated rabbit heart from reoxygenation injury, rat lung from injury resulting from systemic activation of complement, and rat brain from damage caused by four hours of ischemia. Data from these animal studies suggest that flavin therapy holds promise in protecting tissue from the oxidative injuries of myocardial infarction, acute lung injury, stroke, and a number of other clinical conditions. © 1993 Wiley-Liss, Inc.