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Biomedical subjects

O Meyer

Publications and source records attributed to O Meyer.

At least 325 records · Page 18Linked to original sources
PubMed1982

Chemical and spectral properties of carbon monoxide: methylene blue oxidoreductase. The molybdenum-containing iron-sulfur flavoprotein from Pseudomonas carboxydovorans.

Carbon monoxide:methylene blue oxidoreductase, the key enzyme of CO-oxidation in energy metabolism of the carboxydobacterium Pseudomonas carboxydovorans, has been isolated in good yield and purity and found to contain FAD, molybdenum, iron, and labile sulfide in the ratio of 1:1:4:4. The enzyme is, therefore, a new molybdenum-containing iron-sulfur flavoprotein, exhibiting chemical and spectral properties quite similar to those of xanthine oxidase. Analytical data on the spectral characteristics of the enzyme in the oxidized and various reduced states are presented. Carbon monoxide:methylene blue oxidoreductase turned out to be photoreducible in the presence of EDTA and urea and was subject to reoxidation by air oxygen; no flavoprotein semiquinone was formed. Unphysiological electron acceptors, e.g. methylene blue, were used as oxidizing substrates whereas NAD or NADP turned out to be ineffective. Methylene blue reduction with CO was not affected by the presence of allopurinol, and carbon monoxide:methylene blue oxidoreductase was not able to catalyze the reduction of methylene blue with xanthine, adenine, or aldehydes. CO was the only reducing substrate used by the enzyme. Carbon monoxide:methylene blue oxidoreductase formed no sulfite adduct, and the reactivity with ferricyanide or cytochrome c was significant but slow. As known for other molybdenum hydroxylases, carbon monoxide:methylene blue oxidoreductase was rapidly inactivated by methanol, but the enzyme exhibited no ability to catalyze the oxidation of NADH with methylene blue, and NAD was not able to overcome methanol inhibition.

Aldehyde Oxidoreductases↗
PubMed1982

Study of toxicity of butylated hydroxyanisole (BHA) in pregnant gilts and their foetuses.

An embryotoxicity study on butylated hydroxyanisole (BHA) was carried out in SPF pigs (Danish Landrace). BHA was incorporated in the diet and administered to pigs in doses of 0, 50, 200 and 400 mg/kg body wt/day from mating (artificial insemination) to day 110 of the gestation period, when the foetuses were removed. Significant lower weight gain was observed in the dams dosed 400 mg/kg body wt/day. Absolute and relative organ weight for the liver and thyroid gland showed a dose-related increase, BHA neither affected the reproduction data nor the incidence of defects in the foetuses.

Animals↗
PubMed1982

[Soluble SS-A, SS-B and RNP antinuclear antigen antibodies in 66 cases of pure or associated forms of Gougerot-Sjögren syndrome].

In a prospective study, 66 patients fulfilling the criteria of Sjögren's syndrome were evaluated from the standpoint of the presence of soluble SS-A, SS-B and RNP specific nuclear antigen antibodies. There were 25 cases of pure Sjögren's syndrome and 41 cases of this syndrome associated with a connective tissue disease. Anti SS-A antibodies were found in 10 per cent of cases and anti SS-B in 21 per cent, without there being any significant difference in prevalence between pure and associated forms of Sjögren's syndrome. Three patients simultaneously showed anti SS-A and anti SS-B antibodies, four had only anti SS-A and eleven anti SS-B. Amongst the forms associated with a connective tissue disease all of the latter were represented with an equivalent prevalence. 18 per cent of the patients had anti-RNP with a majority of associated forms of Sjögren's syndrome. In this population of 66 patients with Sjögren's syndrome, no clinical manifestation appeared to be correlated with the presence of anti SS-A and SS-B antibodies. Amongst the laboratory features, only cryoglobulins were significantly more frequent.

Adult↗
PubMed1982

[Unclassifiable inflammatory rheumatism with HLA B27].

The authors report on 25 patients carrying the HLA B27 histocompatibility antigen and suffering from un-classifiable inflammatory rheumatism. The group included 12 men and 13 women. At the time of the initial observation, the inflammatory rheumatism was localised particularly in the lower limbs, knees, ankles and heels, in 14 of the cases; 7 of the cases revealed chronic polyarthritis, with a largely symmetrical involvement of the joints in the fingers. At the end of the observation period, which lasted 38 months, on average (from 6 months to 1 1/2 years), the series included 3 cases of sero-negative polyarthritis, with symmetrical involvement of the fingers and bony erosions which can probably be classified with cases of rheumatoid polyarthritis (HLA B27 being a coincidence), 2 certain and 3 possible cases of ankylosing spondylarthritis. For several years following the onset of the disease, the majority of the other patient continued to suffer rheumatism of the lower limbs in exacerbations and often accompanied by talalgia.

Adolescent↗
PubMed1981

[Antibodies against soluble nuclear antigens of the SS-A or SS-B type. Significance in systemic lupus erythematosis (author's transl)].

Thirty-five patients with systemic lupus were investigated for serum antibodies specifically directed against soluble proteic nuclear antigens similar to the SS-A and SS-B antigens. The presence of these antibodies did not make much difference in the clinical and biological symptoms of the disease, except for a higher incidence of Gougerot-Sjögren's syndrome with clinical manifestations. Their prevalence in systemic lupus erythematosus was 35%, anti-SS-A antibodies being more frequent than anti-SS-B antibodies (27% and 4,5% respectively). A third different antibody was found in 3% of the patients. These precipitating anti-SS-A or SS-B antibodies have no prognostic significance. They may be present in the absence of antinuclear antibodies detectable by immunofluorescence.

Adult↗
PubMed1981

Role of carboxydobacteria in consumption of atmospheric carbon monoxide by soil.

The carbon monoxide consumption rates of the carboxydobacteria Pseudomonas (Seliberia) carboxydohydrogena, P. carboxydovorans, and P. carboxydoflava were measured at high (50%) and low (0.5 mul liter) mixing ratios of CO in air. CO was only consumed when the bacteria had been grown under CO-autotrophic conditions. As an exception, P. carboxydoflava consumed CO also after heterotrophic growth on pyruvate. At low cell densities the CO consumption rates measured at low CO mixing ratios were similar in cell suspensions and in mixtures of bacteria in soil. CO consumption observed in natural soil (loess, eolian sand, chernozem) as well as in suspensions or soil mixtures of carboxydobacteria showed Michaelis-Menten kinetics. The K(m) values for CO of the carboxydobacteria (K(m) = 465 to 1,110 mul of CO liter) were much higher than those of the natural soils (K(m) = 5 to 8 mul of CO liter). Considering the difference of the K(m) values and the observed V(max) values, carboxydobacteria cannot contribute significantly to the consumption of atmospheric CO.

Journal Article↗
PubMed1981

[Animal models in lupus].

The study of spontaneous animal models of the lupoid disease has permitted a better understanding of the intermediary mechanisms which lead to the production of auto-anti-polymorphonuclear antibodies, and of glomerulo-nephritis by means of immune complexes. In comparison with a primitive thymic deficiency which causes a disorder in immunity regulation, under the control of activating and suppressing T lymphocytes, these models have demonstrated the probable role of intrinsic hyper-activity of the B lymphocytes. The association of these two disturbances seems necessary for the development of the disease in NZB and F1 New Zealand mice (NZB X NZW); nonetheless, the studies of other murine models (notably MRL/1 pr and B X SB mice) reveal a great diversity in lymphocytic disturbances, capable of leading to the production of auto-antibodies. These models allow genetic control of lupoid disease to be undertaken. Finally, canine lupus and Aleutian mink disease underline the possible role of a transmittable viral agent.

Aleutian Mink Disease↗
PubMed1980

Magnesium stearate given perorally to rats. A short term study.

Magnesium stearate was fed to groups of 20 male and 20 female rats at levels of 0, 5, 10 and 20% in a semisynthetic diet for 3 months. Decreased weight gain was found in males in the 20% group. Urolithiasis was found in 8 males and in 7 females in the same group. Reduced relative liver weight was seen in males in the 10% and in the 20% groups, and an increased amount of iron was found in the livers of the 20% group. Nephrocalcinosis was reduced in females in the 20% group. In this experiment the no-effect-level is estimated to be 5% magnesium stearate in the diet, corresponding to 2500 mg/kg body wt/day.

Animals↗
PubMed1980

Behavioural and developmental effects of butylated hydroxytoluene dosed to rats in utero and in the lactation period.

Butylated hydroxytoluene (BHT) 500 mg/kg body wt/day was given in the diet to Fo-rats from 6 weeks of age to weaning of the F1-generation (growth period to age 19 week, gestation period and lactation period) and subsequent to F1-animals until 21 days of age. Body weight of F0-animals was recorded, and the influence on the F1-generation was investigated applying crossfostering. Mortality, litter size, weight gain and some developmental events as well as tests for auditory and visual function and locomotor coordination in the F1-generation were recorded. The applied dose of BHT exerted a significant adverse effect on body weight in both F0 and F1-animals and on several developmental parameters in F1-animals. The effects arose during the lactation period.

Animals↗
PubMed1980

Carbon monoxide:methylene blue oxidoreductase from Pseudomonas carboxydovorans.

The enzyme carbon monoxide:methylene blue oxidoreductase from CO autotrophically grown cells of Pseudomonas carboxydovorans strain OM5, was purified to homogeneity. The enzyme was obtained in 26% yield and was purified 36-fold. The enzyme was stable for at least 6 days, had a molecular weight of 230,000, gave a single protein and activity band on polyacrylamide gel electrophoresis, and was homogeneous by the criterion of sedimentation equilibrium. Sodium dodecyl sulfate gel electrophoresis revealed a single band of molecular weight 107,000. Carbon monoxide:methylene blue oxidoreductase did not catalyze reduction of pyridine or flavin nucleotides but catalyzed the oxidation of CO to CO2 in the presence of methylene blue, thionine, toluylene blue, dichlorophenolindophenol, or pyocyanine under strictly anaerobic conditions. The visible spectrum revealed maxima at 405 and 470 nm. The millimolar extinction coefficients were 43.9 (405 nm) and 395.5 (275 nm), respectively. Absorption at 470 nm decreased in the presence of dithionite, and the spectrum was not affected by the substrate CO. Maximum reaction rates were found at pH 7.0 and 63 degrees C; temperature dependence followed the Arrhenius equation, with an activation energy (delta H degree) of 36.8 kJ/mol (8.8 kcal/mol). The apparent Km was 53 microM for CO. The purified enzyme was incapable of oxidizing methane, methanol, or formaldehyde in the presence of methylene blue as electron acceptor.

Carbon Monoxide↗