Effects of intracortical injection of blood and blood components on the electrocorticogram

Long term effects of the intracortical implantation of blood and blood products on the electrocorticogram were studied in cats and guinea pigs. Focal epileptiform paroxysmal discharges developed after implantation of whole blood, hemolyzed erythrocytes, methemoglobin, ferritin, ferrous chloride, ferric chloride, fibrinogen, hemin, and cottonoid. In each group recurrent paroxysmal discharges became more prominent and more frequent after several months, suggesting a physiological change caused by a breakdown product of blood. The lesions were characterized by varying degrees of cell loss, iron deposition and glial proliferation. It is thought that posttraumatic epilepsy, which is frequently accompanied by extravasation of blood into the brain, might share a similar physiopathogenesis.

Rat liver regeneration in the presence of nonbenzenoid aromatic agents: ferrocenes and cycloheptatrienes

The extent of liver regeneration in partially hepatectomized rats was increased over a period of 10 days on feeding a basal diet supplemented with 1,1'-diacetylferrocene at 0.15% by weight but the respective differences over the controls were not significant with diets containing ferrocene (0.10 and 0.30%) and acetylferrocene (0.10%) or on sc injection of these agents in peanut oil solution. Tropolone and colchicine supplemented at 750 and 100 PPM, respectively, depressed the regenerative process. The wet and dry liver weight percentages were increased in intact rats fed acetylferrocene (0.15%) or diacetylferrocene (0.060%) but not with ferrocene (0.20%) or with the three injected by the sc route. Hepatic iron deposition was extensive in operated rats fed ferrocene and diacetylferrocene but was far lower in the intact animals on these diets or in the groups injected with the agents.

Lysis of erythrocytes as a result of microsomal lipid peroxidation induced by CCl4 or FeCl2

Rat liver microsomal lipid peroxidation as measured by malondialdehyde formation induced by the NADPH-dependent metabolism of CCl4 led to a concomitant lysis of erythrocytes added to the incubation mixture. The hemolytic process was closely related to the rate of malondialdehyde formation. The time elapsed for initiation and completion of hemolysis and the rate of malondialdehyde formation correlated well with the concentration of CCl4 used. Similar results were obtained during FeCl2-induced microsomal lipid peroxidation and hemolysis. The occurrence of products with hemolytic activity during CCl4-induced microsomal lipid peroxidation is discussed in relation to the hepatotoxicity of CCl4.

Recovery of chill-stressed Vibrio parahaemolyticus from oysters with enrichment broths supplemented with magnesium and iron salts

The effects of magnesium and iron salts on the recovery and growth of chill-stressed cells of Vibrio parahaemolyticus were studied. Supplementation of glucose salt Teepol (GST) broth with 20 to 100 mM of Mg2+ significantly (P less than or equal to 0.05) increased the number of cells recovered from oyster homogenate stored at 3 degrees C. Populations detected with supplemented GST were comparable to those obtained with Horie arabinose ethyl violet (HAE) broth, with or without Mg2+. Recovery of V. parahaemolyticus from homogenates stored at -18 degrees C was also improved when enrichment broths supplemented with Mg2+ were used. Ferric iron (added as FeCl3) at 240 microM in GST and 240 or 960 microM in HAE significantly enhanced the extent of recovery of chilled cells. Ferrous iron was generally less effective. Teepol did not influence the growth of nonchilled cells, but significantly reduced the viable population in suspensions of chilled cells when used at a level of 0.4% in GST. The relatively high pH (9.0) of HAE caused a significant reduction in the number of viable, chill-stressed cells of V. parahaemolyticus. The overall results indicated that HAE broth is superior to GST for recovering V. parahaemolyticus from refrigerated and frozen oyster homogenates.

Inhibitory effects of aminoglycoside antibiotics on reduction of cytochrome c from Candida krusei

Five aminoglycoside antibiotics (AGAs)--kanamycin (KM), bekamycin (AKM), dibekacin (DKB), ribostamycin (RSM) and paromomycin (PRM)--were studied for their effects on the nonenzymic reduction of cytochrome c by FeSO4 (Yamabe's system). Their inhibitory activity was in the order: DKB greater than AKM greater than KM greater than RSM greater than PRM. As this order correlated closely with that of the antibacterial activity of AGAs, Yamabe's system has proved useful in predicting the latter activity. Divalent metal ions other than Fe2+ enhanced the AGA-dependent inhibition of Yamabe's system in the order: Cu2+ greater than Mn2+ greater than Zn2+ greater than Co2+ greater than Ni2+ greater than. This order was similar to that of stability constants with general chelators except for the low positions of Ni2+ and Co2+. These findings suggested a metal chelation with free or bound Fe2+ for the action mechanism of AGAs on Yamabe's system and the bacterial growing system. The antagonistic effects of exogenous Fe2+ on the antibacterial activity against Staphylococcus aureus and Escherichia coli as measured by the agar dilution method supported this concept. A dual relationship of molecular structure with chelating and antibacterial activities demonstrated the importance of high molecular basicity in a potent AGA. However, the combination effect of pipemidic acid (stimulator on Yamabe's system) with KM was different from that with 1,10-phenanthroline (inhibitor on Yamabe's system) as measured by Dye's method using Pseudomonas aeruginosa.

Iron-deficiency anaemia and its effect on worker productivity and activity patterns

The effects of iron-deficiency anaemia on workers productivity were studied in a tea plantation in Sri Lanka. The quantity of tea picked per day was studied before and after iron supplementation or placebo treatment. After one month's treatment significantly more tea was picked when the haemoglobin (Hb) concentration was increased by iron supplementation than when it was not. The degree of improvement was greater in more-anaemic subjects (those with concentrations of 6.0-9.0 g Hb/dl). The level of physical activity of anaemic subjects in their everyday environment was also recorded for four or 24 hours continuously both before and after treatment. After three weeks these levels was significantly greater in the iron-treated than matched placebo-treated subjects. The economic implications of increased work productively with iron treatment are evident, particularly in developing countries. These results also provide strong evidence for the clinical impression that people with iron-deficiency anaemia suffer from tiredness and weakness.

Effect of ionophores on carrier-mediated electron translocation in ferricyanide-containing liposomes

Ferricyanide-containing liposomes were used as a system to compare the electron- and proton-translocating properties of six redox reagents commonly used as electron donors for biochemical systems. The effects of different ionophore combinations on the ferricyanide-reduction rate were generally consistent with the expected proton- and electron-translocating properties of the mediators. The transmembrane pH gradient produced by hydrogen carriers was demonstrated. Nigericin or valinomycin plus carbonyl cyanide p-trifluoromethoxyphenylhydrazone are capable of collapsing this gradient and of stimulating ferricyanide reduction mediated by this type of carrier. No pH gradient is produced with the electron carrier 1,1'-dibutylferrocene. In the presence of tetraphenylboron anion, which is needed for this carrier to act as an efficient mediator, addition of valinomycin alone is sufficient to obtain full stimulation of ferricyanide reduction. NNN'N'-Tetramethyl-p-phenylenediamine does not behave as a simple electron carrier. During NNN'N'-tetramethyl-p-phenylenediamine-mediated ferricyanide reduction protons are translocated across the membrane and accumulated in the vesicles. This is not due to the presence of demethylated impurities in the NNN'N'-tetramethyl-p-phenylenediamine sample, but may be the result of an accumulation of oxidation products other than the Wurster's Blue radical. These results suggest a reconsideration of studies on protonmotive forces across membranes where NNN'N'-tetramethyl-p-phenylenediamine is used as a mediator.

Enhancement of the chromosome-damaging action of ascorbate by transition metals

Freshly prepared ascorbate inhibited mitosis and induced chromosome aberrations in cultured Chinese hamster ovary cells. Cu(II) and Mn(II) (10(-4) or 10(-5) M) enhanced both actions. Fe(II) and Fe(III) (10(-4) or 10(-5) M) reduced or abolished the mitosis-inhibiting action of ascorbate. At 10(-4) M, Fe(II) and Fe(III) strongly enhanced the chromosome-damaging capacity of ascorbate. Up to 100% of all examined metaphase plates had multiple chromosome exchanges or breaks. Since the cytostatic and clastogenic effect of ascorbate of H2O2 to induce chromosome aberrations was examined. H2O2 and a H2O2: Fe(II) mixture (Fenton reagent) induced chromosome breaks and exchanges but to a lesser degree than did ascorbate: Cu(II), Mn(II), Fe(II), or Fe(III) mixtures. Whether the strong chromosome damaging capacity of ascorbate plus transition metals as seen in the in vitro test system poses a health hazard only properly designed in vivo studies can reveal.

[Role of NADPH-dependent lipid peroxidation in the oxidase inactivation in mixed hepatic microsomal function]

When mouse liver microsomes were preincubated at 37 degrees with buffer, the monooxygenase activity was nearly constant and lipid peroxidation very low over 15 min. When preincubated with NADPH, there was an increase in lipid peroxidation accompanied by loss in enzyme activity (about 40%). The addition of EDTA 5 or 40 mM depressed lipid peroxidation and protected the monooxygenase activity with a rate increasing with concentration. The addition of FeSO4 0.5 mM had only little effect one enzyme activity whereas stimulated the response of the 2-thiobarbituric acid test.

Red cell mass during and after normal pregnancy

Red cell mass, derived from plasma volume and haematocrit, was calculated serially in 45 healthy women during pregnancy and 4 to 6 months after delivery. Compared to the non-pregnant, postpartum value there was a reduction of approximately 100 ml at 12 weeks gestation. An increase in red cell mass occurred thereafter: at 36 weeks gestation values 180 ml greater than the non-pregnant were found. Iron and folic acid supplements almost doubled this increment to 349 ml of red cells.

Intracranial vasospasm: a study with iron compounds

The effects of topically applied hemoglobin, methemoglobin, hemin, ferrous chloride (FeCl2) and ferric chloride (FeCl3) were investigated by observation through the operating microscope to determine their effect on the normal and spastic canine basilar artery. Following transclival exposure, the artery was made spastic by puncture or topical barium chloride. No consistent changes in arterial diameter were seen with topical hemoglobin, methemoglobin, or hemin. The buffered ferrous ion (Fe++) caused marked vasodilation at concentrations of 10 microgram/ml. The buffered ferric ion (Fe++) caused mild vasoconstriction at similar concentrations. The possible role of iron (a component of hemoglobin) in vasospasm following subarachnoid hemorrhage and subsequent hemoglobin degradation is discussed.

Light generation with Fenton's reagent. Its relationship to granulocyte chemiluminescence

A simple chemical system consisting of FeSO4 and H2O2 (Fenton's reagent) was shown to emit light (chemiluminescence). The addition of tryptophan to the reaction markedly enhanced light production. Very little chemiluminescence was observed when H2O2 was omitted from the reaction and when ferric, instead of ferrous, ions were used. Hydroxyl radical (OH.) and singlet oxygen (1 deltagO2) quenchers suppressed chemiluminescence of the FeSO4 + tryptophan + H2O2 system; and, deuterium oxide (2H2O) enhanced chemiluminescence of both FeSO4 reactions. These observations suggest that a radical chain reaction involving both OH. and 1 deltag O2 is responsible for the chemiluminescent reactions. Six iron-containing proteins, some of which are located within granulocytes, all emitted light in the presence of H2O2. Since iron and H2O2 are present in metabolically stimulated granulocytes, it is likely that chemiluminescent reactions similar to the ones demonstrated in this study account for part of the chemiluminescence of activated granulocytes.

Studies of the microaerophilic nature of Campylobacter fetus subsp. jejuni. I. Physiological aspects of enhanced aerotolerance

The aerotolerance of the microaerophilic bacterium Campylobacter fetus subsp. jejuni strain H840 (ATCC 29428) can be enhanced by addition of a combination of ferrous sulfate, sodium bisulfite, and sodium pyruvate (FBP), or of dihydroxyphenyl compounds such as nor-epinephrine (NE), to Brucella broth. Transport of 55Fe3+ was increased by NE, suggesting that ordinary rates of transport, while adequate for growth at 6% O2, might not permit growth at 21% O2. Growth with FBP at 21% O2 did not appreciably affect levels of cytochromes or of various tricarboxylic acid cycle enzyme activities. Activities of certain iron-dependent enzymes (succinate dehydrogenase and aconitate hydratase), and also respiration rates of whole cells, were lower in cells grown at 21% O2 in Brucella broth compared to 6% O2, but FBP did not cause an increase in these activities or rates. FBP caused a decrease in catalase and peroxidase activities. Total superoxide dismutase (SOD) activity increased when cells were grown at 21% O2 with FBP. When grown without FBP, however, the organism possessed SOD activity as high as that in Escherichia coli, and a variant strain of H840 possessed nearly double this activity but was no more aerotolerant than the parent strain. A very oxygen-sensitive strain of C. fetus subsp. intestinalis also possessed high SOD activity. Consequently, total SOD activity in C. fetus does not appear to account for lack of aerotolerance. No evidence that FBPcauses any physiological change in C. fetus that could satisfactorily account for enhancement of aerotolerance could be obtained. It is possible that FBP or NE might not affect some physiological process in the organisms but might instead act on the culture medium.

Lipid peroxidation activity mediated by NADPH-cytochrome C reductase purified from rabbit liver microsomes

Purified NADPH-cytochrome c reductase of rabbit liver microsomes was examined to determine whether or not the reported low lipid peroxidation activity of rabbit liver microsomes is due to the enzyme, NADPH-cytochrome c reductase. NADPH-cytochrome c reductase was purified from phenobarbital-treated rabbit liver microsomes to a specific activity of 14.9 to 21.4 unit per mg of protein with a yield of 15.2 to 16.4%. The purified sample (21.4 unit/mg of protein) was almost homogenous as determined by sodium dodecylsulfate gel electrophoresis. This sample was used for determining lipid peroxidation activity. EDTA and ferrous ion but not ADP were essential requirements for the activity. FMN enhanced the activity when low concentrations of the NADPH-cytochrome c reductase were used for the assay. NADP and 2'-AMP, which are inhibitors of NADPH-cytochrome c reductase, inhibited the lipid peroxidation activity. a-Tocopherol and p-chloromercuribenzoate (PCMB) also inhibited the activity. From these results, we confirmed the rabbit liver microsomal enzyme NADPH-cytochrome c reductase plays a role in lipid peroxidation activity. The reported low lipid peroxidation activity in rabbit liver microsomes does not appear to be caused by the NADPH-cytochrome c reductase.

Induction of transformation competence in Azotobacter vinelandii iron-limited cultures

Azotobacter vinelandii strains UW (Nif+) or UW1 (Nif-) were induced to form competent cells by growing cultures in Burk medium without added iron. Competent cells were generated in either liquid or solid medium. The competent culture was highly colored by the characteristic fluorescent green pigment of A. vinelandii but all pigmented cultures were not competent. In liquid culture, competent cells required a fixed nitrogen source (ammonia, nitrate, or urea) that was also a nitrogenase repressor. Glucose, sucrose, glycerol, and mannitol (1% w/v) were excellent C-sources for competence induction while acetate (1% w/v) and beta-hydroxybutyrate (0.2% w/v) were ineffective. Cells induced in liquid culture remained competent for a 12-h period before the end of the exponential growth phase, then competence decreased rapidly upon the initiation of the stationary phase of growth.

Interaction of bleomycin with DNA

The sequence of oligonucleotides produced by the action of bleomycin and ferrous ion on double- and single-stranded DNA has been determined. In the presence of ferrous ion, bleomycin promotes cleavage at G-T and G-C sequences, while high concentrations of ferrous ion alone result in strand scission that is not base specific. In the presence of bleomycin and ferrous ion, pyrimidine bases located to the 3' side of guanosine are released preferentially and a low molecular weight product that forms a chromophore with thiobarbituric acid is produced from the deoxyribose moiety. Oligonucleotides produced by the action of bleomycin differ slightly in electrophoretic mobility from those produced by chemical or enzymatic cleavage. A model is proposed to explain the interactions of bleomycin with DNA.

Effects of various compounds on lipid peroxidation mediated by detergent-solubilized rat liver NADPH-cytochrome C reductase

A reconstituted lipid peroxidation system containing NADPH-cytochrome c reductase isolated from detergent-solubilized rat liver microsomes was used to determine the effects of several compounds, including drugs, on the lipid peroxidation activity. EDTA and ferrous ion were essential requirements for reconstitution of the activity. The addition of 1,10-phenanthroline to the system containing both EDTA and ferrous ion further enhanced the activity. Pyrocatecol, thymol, p-aminophenol, imipramine, p-chloromercuribenzoate (PCMB) and alpha-tocopherol exhibited strong inhibition, aniline, N-monomethylaniline, aminopyrine, benzphetamine, SKF 525-A and NADP exhibited moderate inhibition, and phenol, benzoic acid, acetanilide and nicotinamide exhibited less or no inhibition at the concentrations lower than 1000 micron M. Metal ions such as Hg+, Hg2+, Co2+, Cu2+, Mn2+ and U6+ inhibited lipid peroxidation strongly. In addition, Cd2+, St2+ and Ca2+ exhibited less potent to moderate inhibition, and Ba2+ and Mg2+ were without effects on the activity. Among sulfhydryl compounds tested, dithiothreitol inhibited lipid peroxidation to a greater extent than did the other three compounds, glutathione, cysteine and mercaptoethanol.

Characteristics of the activation by dithiothreitol and Fe(2+) of tryptophan hydroxylase from the rat brain

The preincubation of tryptophan hydroxylase extracted from various areas of the central nervous system of the rat with 30 mM dithiothreitol and 50 muM ferrous ammonium sulfate under nitrogen atmosphere resulted in a persistent increase of its activity. Studies on the enzyme characteristics indicated that this activation was associated with a doubling in its Vmax and a shift (from 7.6 to 7.2) of the optimal pH for its activity. In contrast, the molecular weight and the apparent affinities of tryptophan hydroxylase for its pterin cofactor and for tryptophan were not significantly altered by the preincubation with dithiothreitol and ferrous ammonium sulfate. Since this treatment did not prevent the stimulatory effects of various compounds (phosphatidylserine, ATP and MG(2+), Ca(2+)) on tryptophan hydroxylase activity, this might be a good procedure to activate this enzyme with only minor changes in its regulatory properties.

Methods for detecting disulfiram in biologic fluids: application in studies of compliance and effect of divalent cations on bioavailability

Studies regarding the efficacy of disulfiram in the treatment of alcoholism have not included a method of evaluating compliance to the prescribed regimen. This article outlines current methods used to detect disulfiram in blood, breath, and urine.

Effect of Fe2+ and Mn2+ on 3-mercaptopicolinate inhibition of cytosolic and mitochondrial phosphoenolpyruvate carboxykinase of five species

Liver cytosolic or mitochondrial fractions of five species were incubated with 30 micrometer Fe2+ or with 100 micrometer Mn2+ prior to assaying for phosphoenolpyruvate carboxykinase (GTP:oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.32) acticity in the presence of 3-mercaptopicolinate. Only the cytosolic carboxykinases were activated 3--4-fold by Fe2+ or Mn2+. Fe2+ enhanced the inhibitory potency of 3-mercaptopicolinate 10--50-fold against the cytosolic and the mitochondrial carboxykinases, but Mn2+ was ineffective. Mn2+ interfered with Fe2+ -enhancement of inhibition by 3-mercaptopicolinate in a manner competitive with Fe2+. It is hypothesized that Fe2+ and 3-mercaptopicolinate form a coordination complex that inhibits the carboxylkinases and that 3-mercaptopicolinate does not blind to a carboxykinase containing Mn2+.

The effect of compounds which degrade hydrogen peroxide on the enumeration of heat-stressed cells of Salmonella senftenberg

Greater than 90% of heat-stressed cells of Salmonella senftenberg failed to grow on trypticase soy agar. Adding to this medium compounds which are capable of degrading hydrogen peroxide allowed growth of the heat-injured cells. These compounds did not stimulate growth of heated cells of Streptococcus faecium, an organism which does not possess catalase.

The role of iron in prostaglandin synthesis: ferrous iron mediated oxidation of arachidonic acid

Arachidonic acid (AA) is the essential substrate for production of platelet endoperoxides and thromboxanes. Iron or heme is an essential cofactor for the peroxidase, lipoxygenase and cyclo-oxygenase enzymes involved in formation of these products. The present study has examined the direct interactions between iron and arachidonic acid. Iron caused the oxidation of AA into more polar products which could be detected by UV absorbtion at 232 nM or the thiobarbituric acid (TBA) reaction. High pressure liquid chromatography, chem-ionization and electron-impact mass spectrometry and nuclear magnetic resonance spectroscopy suggest that the major product was a hydroperoxide of AA. Ferrous iron (Fe++) and oxygen were absolute requirements. Fe++ was converted to the ferric iron (Fe+++) state during oxidation of AA, but Fe+++ could not substitute for Fe++. No other enzymes, cofactors or ions were involved. Conversion of AA to a hydroperoxide by Fe++ was inhibited by the antioxidant, 2, (3)-Tert-butyl-4-hydroxyanisole, the radical scavenger, nitroblue tetrazolium, and iron chelating agents, including EDTA, imidazole and dihydroxybenzoic acid. The reaction was not affected by superoxide dismutase, catalase or aspirin. These findings and preliminary studies of the Fe++ induced oxidation product of AA as a substrate for prostaglandin synthesis and inhibitor of prostacyclin production indicate the critical role of Fe++ in AA activation.

The effect of nalidixic acid group compounds on reduction of cytochrome c from horse heart and Candida krusei

Reduction of cytochrome c from both horse heart and Candida krusei by FeSO4 has been demonstrated. This reaction was stimulated by nalidixic acid and structurally related compounds, and the effect was more pronounced for the yeast cytochrome. Divalent metal ions other than Fe2+ lessened or abolished the stimulation by these compounds. Fe2+ and other metal ions altered the spectra of nalidixic acid and related compounds indicating the formation of metal chelate complexes. 1,10-Phenanthroline inhibited reduction of cytochrome c b Fe2+. Other divalent metal ions relieved the inhibition, probably by forming chelates with 1,10-phenanthroline. The results suggest that metal ion chelation may be involved in the molecular mode of action of nalidixic acid and related drugs. The relevance of this artificial electron transfer system to bacterial electron transfer in vivo is discussed.

Inhibition of neurohypophysial hormone release from the isolated rat neural lobe by ferrous chloride in the incubation medium

A. R. C. Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT

(Received 12 April 1977)

Both electrical stimulation with steel microelectrodes and injection of iron salts into the preoptic area lead to an increased concentration of luteinizing hormone (LH) in the plasma and ovulation (Everett & Radford, 1961; Dyer & Burnet, 1976).

Initially, iron salts were thought to excite nerve cells but Fe2+ and Fe3+ ions, like most cations, when applied to nerve cells by micro-iontophoresis, inhibit firing (Dyer & Burnet, 1976). Dyer & Burnet (1976) proposed a number of alternative explanations for the electrochemical stimulation of ovulation. They suggested that ferrous or ferric ions might kill or damage some neurones and the resulting cell disruption might lead in turn to the liberation of a sufficient quantity of luteinizing hormone releasing hormone (LH-RH) into the hypophysial portal vessels to cause a surge of LH. Alternatively, ovulation might be stimulated by

Enhancement of NADPH-dependent lipid peroxidation activity by ethylene-diamineteraacetic acid (EDTA) in the presence of ferrous ion in rabbit liver microsomes

The addition of EDTA to the incubation mixture containing rabbit liver microsomes and ferrous ion resulted in 2-fold increase of lipid peroxidation activity. Such an enhancement was not observed in rat liver microsomes. The maximum lipid peroxidation activity seen in rabbit microsomes in the presence of EDTA and ferrous ion was about 80% that seen in rat liver microsomes. From these results, it is likely that low lipid peroxidation activity in rabbit liver microsomes may account for the insufficiency of an EDTA-LIKE FACTORS(S) IN RABBIT LIVER MICROSOMES.

Cause of decrease of ethylmorphine N-demethylase activity of lipid peroxidation in microsomes from the rat, guinea pig and rabbit

There were marked differences among animal species between NADPH-dependent and ascorbic acid-Fe++-dependent lipid peroxidation. In NADPH-dependent lipid peroxidation, this activity occurred to the greatest extent in rats followed by guinea pigs and rabbits and such was much lower in rabbits than in guinea pigs. On the other hand, rabbit microsomes exhibited higher lipid peroxidation activity than guinea pigs in ascorbic acid plus Fe++ or Fe++-dependent lipid peroxidation although the activity was still lower than in rats. The ascorbic acid plus Fe++-stimulated lipid peroxidation produced a decrease in ethylmorphine N-demethylase activity which was closely related to ethylmorphine-enhanced NADPH-cytochrome P-450 reductase activity but was not related to the change of the apparent content of cytochrome P-450 in all animal species. These results indicate that decrease of NADPH-cytochrome P-450 reductase activity induces a decrease in ethylmorphine N-demethylase activity by lipid peroxidation.

[Factors influencing formation of dinitrosyl complexes of non-heme iron in vitro preparations of mouse liver and yeasts]

Total content of Fenh and its amounts incorporated into paramagnetic dinitrozyl complexes of Fenh (complexes 2.03) which are formed in vitro in homogenates of mouse liver and yeast preparations treated with nitrogen oxide was determined by means of chemical and ESR methods. Formation of the complexes 2.03 in the liver homogenate is limited by the content of easily dyalized weakly bound Fenh, in yeasts--by the content of pair RS-groups. It is suggested that in the liver preparation Fenh incorporated into the complexes 2.03 is determined by the interaction of reduction cytoplasm agents with ferritin. A change in the content of Fenh may affect the appearance and disappearance of the complexes 2.03 in animal tissues in vivo.

Stimulative effects of chelating agents, 2,2'-bipyridine and 1,10-phenanthroline, on lipid peroxidation in rat liver microsomes

Well known lipid peroxidation inhibitors, 1,10-phenanthroline and 2,2'-bipyridine, stimulated microsomal NADPH- and ascorbic acid-dependent lipid peroxidation when low concentrations of these chelating agents were added to incubation mixture. The stimulatory effects of the chelating agents on lipid peroxidation were enhanced when ferrous ion was added together with the chelating agents to the mixture at a molar ratio of 1:1. Ethylenediaminetetraacetic acid (EDTA) had no stimulatory effect on lipid peroxidation. Ferrous ion-EDTA complex increased lipid peroxidation by only 20-30%, which was lower than that obtained by addition of the same concentration of ferrous ion alone. On the other hand, manganese and calcium ions, which are also inhibitors of lipid peroxidation, had no ability to stimulate lipid peroxidation even in the presence of extra ferrous ions. Changes in the lipid peroxidation by chelating agents affected the apparent activity of ethylmorphine N-demethylation.

Biochemical basis of skeletal defects induced by hydralazine: inhibiton of collagen synthesis and secretion in embryonic chicken cartilage in vitro

Hydralazine (1-hydrazinophthalazine) produces skeletal defects resembling those observed in experimentally induced manganese deficiencies. Since glycosylation of collagen, a step preceding its secretion, requires Mn2+, the effect of hydralazine on collagen secretion and the formation hydroxylysine glycosides was examined in explants of embryonic chicken long-bone rudiments. Auto-radiographic studies showed that hydralazine blocked collagen secretion. Secretion was restored by Fe2+ alone or Fe2+ + Mn2+ but not by Mn2+ alone, suggesting that a Fe2+-requiring step was involved. Biochemical analyses showed that hydralazine inhibited the formation of hydroxylysine, a step requiring Fe2+, but it did not inhibit the formation of hydroxylysine-glocosides by Mn2+-requiring steps, although the reaction was inhibited in vitro. Hydralazine also failed to inhibit intracellular mucopolysaccharide synthesis which involves several Mn2+-requiring enzymes. These observations suggest that the deleterious effects of hydralazine on bones are caused by its inhibition of hydroxylation steps in collagen synthesis.

Toxicity of radiolytic products from 60 Co-treated starch on microorganisms

The radiolytic products of a 60Co-irradiated starch are sensitive to the action of catalase, peroxidase and ferrous ions: extracts of irradiated starch so treated loss their toxicity for Escherichia coli. After eliminating the reductones, the toxic activity is attributed to the peroxides and more especially to hydrogen peroxide. Artificial reconstitution of an irradiated starch extract confirms this conclusion and reveals a secondary toxic action of formaldehyde.

Inhibition of lysyl hydroxylase by catechol analogs

Catechol analogs inhibit the activity of lysyl hydroxylase (peptidyllysine, 2-oxyglutarate: oxygen 5-oxidoreductase, EC 1.14.11.4), a microsomal enzyme which catalyzes the transformation of certain lysyl residues in collagen to hydroxylysine. Chick embryo lysyl hydroxylase activity was measured by specific tritium release as tritiated water from an L-[4,5-3H]lysine-labelled unhydroxylated collagen substrate prepared from chick calvaria. Catechol analogs did not bind irreversibly to either enzyme or substrate, as full activity was restored with dialysis. Addition of excess cofactor, Fe2+, ascorbic acid, or alpha-ketoglutarate, did not affect inhibition. Kinetic analysis revealed that with respect to collagen substrate, catechol demonstrated a noncompetitive type of inhibition with a Ki of 15 muM.