Search

Kinetic models, incorporating elementary chemical reactions, are used to predict the concentrations of NO (nitric oxide) and CO (carbon monoxide) in spark-ignition engines during the expansion process. The kinetic equations are*** incorporated in a cycle synthesis computer programme, which can be used to calculate the thermodynamic state and the concentration of a number of species in the burnt gas. The stability and accuracy of the programme is discussed and the validity of the results is confirmed by comparing the theoretical predictions with experimental results.

n/a

Summary The effects of carbon monoxide in man are indicated. Especially proposals are given for the calculation of the carboxy-hemoglobin-formation as related to carbon monoxide concentration. General biologic effects due to the change of the equilibrium of the oxygen concentration in blood by carbon monoxide and the inhibition of biological catalysts are discussed. Furthermore, a survey is given on the methods of analyzing carbon monoxide in the gaseous phase and in blood, respectively.

This paper attempts to show that the catalytic properties of zeolitic material may play a role in the synthesis of simple biological molecules from gases commonly found in extraterrestrial atmospheres. Linde X and Y molecular sieves cation-exchanged by Ca2+ and Fe3+ have been heated in the presence of carbon monoxide and ammonia. Amino-acids and u.v. absorbing substances identified by paper chromatography have been extracted from the solid. HCN, the basic molecule involved in the synthesis of those substances has been detected in the gas phase. It is proposed, on the basis of i.r. results, that the amino-acids are hydrolysis products of an undefined polymer.

Crude preparations of Desulfotomaculum nigrificans were found to reduce bisulfite to trithionate, thiosulfate, and sulfide. The bisulfite reductase of this organism was partially purified and observed to reduce bisulfite to trithionate as the major product and with thiosulfate and sulfide as minor products. The enzyme exhibited spectral properties identical to the carbon monoxide-reacting pigment (P582) isolated from this organism. It is concluded that the bisulfite reductase of D. nigrificans is P582 and that this organism utilizes a pathway which involves trithionate during the reduction of bisulfite to sulfide.

S>Glucose, maltose, arabinose, glucuronic acid, gluconic acid, and a series of small dextrins were identified by paper chromatography of highly irradiated potato starch granules. These mono- and oligosaccharides were analyzed by anion exchange column chromatography, and glucose and maltose were determined quantitatively as main fission products. A gas chromatographic analysis of the gaseous products from starch granules after gamma radiation showed the presence of hydrogen, carbon monoxide, and carbon dioxide. From these results, a part of the mechanism of degradation of starch by gamma radiation is discussed. (Abstr. Japan Med., 1: No. 10, 1961).

A metabolic reaction whereby CO is oxidized to CO 2 has been shown to take place in a variety of green algae. The investigation of this reaction was facilitated by the use of 14 CO. The reaction was found to be oxygen dependent with the maximal rate being obtained when the gas phase was approx. 1% O 2 . Although oxidation of CO was observed in the dark, the rate was increased by several fold in the presence of low-intensity light. The optimal pH of the reaction was found to be approx. 7. The K m for the reaction was measured and found to be 0.32 atm. There was an inhibition of the reaction by cyanide, azide, hydroxylamine, 3,4-dichlorophenyl-1, 1-dimethylurea, and formate. On the basis of a study of the reaction products using paper chromatography, it was concluded that CO 2 was the primary product.

This paper describes a new method of producing a crystalline intermediate between the unligated and ligated states of haemoglobin, suitable for X-ray analysis, by the use of a lattice strengthening reagent. Acrylamide is polymerized in the liquid of crystallization after the crystal has grown, forming a stiff supporting gel between the haemoglobin molecules, but not covalent bonds with them. The structure of human haemoglobin A crystallized in the deoxy quaternary structure (T-state † ) and then oxidized by air after lattice strengthening (tertiary structure made met, or r-state) was determined to 3.5 A resolution by the difference Fourier technique. Marked changes in tertiary structure in the region of the haem pockets and the contacts between the subunits (α 1 β 2 ) are observed. The iron is seen to move towards the plane of the porphyrin, causing a change of tilt of the haem. This appears to act as a lever setting in train stereochemical changes that loosen several hydrogen bonds within and between subunits, on which the stability of the tertiary and quaternary deoxy structures depend. The liganding water molecule itself causes a slight opening of the haem pocket in the α subunit, and a substantial one in the β subunit. The structural changes seen here in going from the tertiary deoxy to the aquomet state within the quaternary T-structure are similar, but opposite, to those seen earlier in going from aquomet to deoxy in the quaternary R-structure of BME-haemoglobin. Changes in tertiary structure associated with addition of ligand to the T-structure or the removal of ligand from the R-structure are thus seen to be complementary. Electron density maps show the α haems to undergo autoxidation more readily than the β haems, just as the β haems were reduced more easily than the α haems in BME-haemoglobin.

In 10 sedentary workers, smoking as they felt inclined over a five-hour period in the middle of a typical working day, changing to low nicotine cigarettes (

The metabolism of dicoumarol by rat liver microsomes from untreated and phenobarbital treated rats was studied. Following differential centrifugation of rat liver homogenates only the 104,000 g microsomal fraction supported dicoumarol metabolism. This was found to be strongly dependent on the presence of NADPH or a NADPH-generating system as well as oxygen and it was inhibited by CO. These data indicate that dicoumarol is metabolized by the mixed function oxidase of liver microsomes. The K m and V m for dicoumarol were determined using microsomes from untreated and phenobarbital treated rats. The values of K m were 5·0 × 10 −5 and 3·9 × 10 −5 M, respectively, while the corresponding values of V m were 0·9 and 2·3 nmoles/mg protein/min. The significance of these results is discussed.

The metabolism of two tertiary aromatic phosphines, 3-dimethylaminopropyldiphenylphosphine (a CNS depressant) and diphenylmethylphosphine, was studied. These compounds were incubated with subcellular fractions of rat liver homogenates and found to be enzymatically converted to the corresponding phosphine oxides; the aminophosphine gave rise to an N , P -dioxide. Enzymatic activity was localized in the microsomal fraction and shown to be associated with the cytochrome P-450 mixed function oxidases. The substrates were also found to undergo a facile non-enzymatic reaction with thiols, a factor which portends their possible chronic toxicity.

In eight patients with polycythaemia secondary to hypoxic lung disease 10 elective exchange transfusions were performed to reduce red cell mass, packed cell volume (P.C.V.), and whole blood viscosity. The rationale for reducing P.C.V. is discussed. It is concluded that patients with P.C.V. of 60% or over will benefit from exchange transfusion and that most patients with P.C.V. over 50% and true polycythaemia will also benefit. We also confirm that the technique of exchange transfusion is a rapid, safe, and effective method of achieving large venesections and reducing red cell mass.

In a cross-sectional study carboxyhaemoglobin (COHb) levels in tobacco smokers were found to provide a better indication of a person's risk of having developed certain atherosclerotic diseases, including ischaemic heart disease, than the smoking history. In the age group 30-69 years a person with a COHb level of 5% or more was found to be 21 times (lower 95% confidence limit 3.3 times) as likely to be affected by these diseases as another person of the same age and sex with similar smoking history and current smoking habits but with a COHb level of less than 3%.

Metabolic hydrogenation of the ring A double bond in testosterone and its conjugates were studied by incubating 14C-testosterone, 14C-testosterone 17-N-acetylglucosaminide and 3H-testosterone 17-glucosiduronate with 20000×g or 105000×g supernatant fluids and microsomal fraction of male rat liver homogenate under carbon monoxide atmosphere or in air. It was demonstrated that in contrast to testosterone the conjugates were not good substrates for microsomal l4-5α-hydrogenase as well as for hydroxylases, while they were better substrates for soluble l4-5β-hydrogenase than testosterone. These findings are consistent with the observations on in vivo metabolism of testosterone and its conjugates in man.

The effect of phenobarbital (PB) pretreatment of young male rats on the metabolism in vivo and in vitro of the carcinogen N -2-fluorenylacetamide (FAA) was studied. PB increased the urinary excretion of 14 C from labeled FAA, mainly as met-abolites conjugated with glucuronic acid. There was a small drop in excretion of sulfuric acid conjugates. In the glucosiduronic acid fraction, there were increases in the N - and 7-hydroxy derivatives of FAA and a decrease in the 5-hydroxy compound, while the 3-hydroxy metabolite was virtually unchanged. The concentration of metabolites of FAA in the liver was considerably lower, as was the amount of isotope bound to DNA. This important finding, correlated with a reduced carcinogenicity of FAA in rats given PB, is ascribed to increased conjugation with glucuronic acid and lesser formation of sulfate esters. The microsomal fraction in vitro from the livers of young rats yielded metabolites of FAA, in decreasing order, hydroxylated at 7-, 5-, N - and 3-. Carbon monoxide significantly inhibited formation of the 7-hydroxy metabolite but elevated somewhat that of the N -hydroxy compound. Pretreatment with PB increased cytochrome P-450 and hydroxylation at all positions 2- to 4-fold, the greatest effect being with N -hydroxy-FAA. With microsomes from PB-treated rat livers, carbon monoxide depressed hydroxylation at the 3-position, while N -hydroxylation was least affected. Because hydroxylation of FAA occurs at several well-defined ring positions and on the amido nitrogen, FAA is a good substrate to explore the mechanisms of hydroxylation reactions. The data obtained suggest that these metabolic reactions are performed by a family of related enzyme systems.

A dissimilatory sulfate-reducing bacterium was isolated which differed in morphology and pigment content from previously described species. The organism was mesophilic, obligately anaerobic, gram-negative, nonsporulating, long, and slender with one polar flagellum. Whole cells fluoresced red at neutral p H when excited with light at 365 nm owing to the presence of a pink pigment. Desulfoviridin was present. Reduced minus oxidized spectra of whole cells showed peaks in the position of a c -type cytochrome characteristic of Desulfovibrio species and peaks at about 629 and 603 nm. CO difference spectra showed the presence of a CO-binding pigment with a peak at 593 nm. Lactate and pyruvate supported growth in the presence of sulfate but not in its absence. Sulfate, sulfite, and thiosulfate served as electron acceptors for growth. Hydrogenase was present. The deoxyribonucleic acid had a buoyant density of 1.722 g/cm 3 and a guanosine plus cystosine molar percentage of total bases calculated by two different methods of 61.2 or 63.2.

In a survey of mice from 40 inbred strains, largely previously untested, four alleles were distinguished at the Hba locus, determining structure of adult mouse hemoglobin α chain. This finding supports and extends previous sequence studies by others. Methods are given by which each phenotype was characterized by its solubility profile at varying pH and by its chromatography pattern. Concordance was complete between histidine-positive αT-4 (defining Hbac) and high-intermediate solubility profile. In three inbred strains, a distinct new low-solubility profile, not associated with his-positive αT-4, was recognized, and mice with this phenotype were classified as Hbad. Implications of observed widely distributed four-allele polymorphism of mouse hemoglobin α-chain structure are discussed.

1. 1. The seven major hemoglobin zones of Oncorhynchus nerka were designated together with their subunit structures, in parentheses, HbNerka Sa(αSsαSfβ2Sf), HbNerka Sb(αSsαSfβSsβSf), HbNerka Sc(αSsαSfβ2Ss), HbNerka Fa(α2FβFmβFf), HbNerka Fb(α2Fβ2Ff), HbNerka Fc(α2FβFsβFf), HbNerka Fd(α2Fβ2Fs). At least eight structural genes code for the eight polypeptides involved. 2. 2. Juvenile O. nerka lacks polypeptide βSs and hence hemoglobin HbNerka Sb and HbNerka Sc but possesses an additional polypeptide βFm resulting in hemoglobin HbNerkaFa. 3. 3. The heterozygous HbNerkaFc is not only present in hemolysates near neutral pH, but also forms HbNerkaFb and HbNerkaFd in vitro at pH 8·5. No evidence of hybridization was found between the cathodal and anodal hemoglobins. 4. 4. The hemoglobins of O. keta, O. kisutch, O. gorbuscha, O. tshawytscha and Salmo gairdneri also consist of molecular species with up to 4 different polypeptides.

In an in vitro system consisting of rat liver microsomes and NADPH, significant lipid peroxidation was observed along with a concomitant loss of cytochrome P-450. This spectral loss of cytochrome P-450 was shown to be the result of a breakdown of cytochrome P-450 heme. Inhibitors of lipid peroxidation also prevented the loss of cytochrome P-450, demonstrating a direct relationship between lipid peroxidation and breakdown of cytochrome P-450 heme. This breakdown of cytochrome P-450 heme during lipid peroxidation is unrelated to the degradation of cytochrome P-450 heme by an active metabolite of certain allyl-containing barbiturates and barbiturate related compounds. In addition, it appears that different breakdown products of heme are produced by these two mechanisms.

A catalytic converter for controlling automobile exhaust emissions was evaluated in California in 1964. Results from this fleet test and subsequent analysis of the spent catalyst are presented. Statistical analysis of dynamometer test results indicates a strong effect of tetraethyl lead content of the gasoline on activity decline. Analysis of spent catalyst revealed that both surface area and accumulated lead are major factors in activity decline. Above 100 m2/g a further increase in surface area at constant lead level resulted in a decline in activity.