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Biomedical subjects

G Reuter

Publications and source records attributed to G Reuter.

At least 127 records · Page 7Linked to original sources
PubMed1989

Partial purification and characterization of sialate O-acetylesterase from bovine brain.

From bovine brain an esterase was purified 2,600-fold in an overall yield of 5.6%. For the isolation ion-exchange chromatographies, gel filtration, and preparative isoelectric focusing were used. The molecular mass is 56 kDa after gel chromatography on Sephacryl S-200 and 51 kDa after HPLC, the pH-optimum at 7.4, and the isoelectric point in the range of pH 5.8-6.1, as estimated from preparative isoelectric focusing. The substrate specificity of this enzyme was tested with various naturally occurring O-acylated sialic acids, synthetic carbohydrate acetates, and other esters. Besides aromatic acetyl esters such as e.g. alpha-naphthyl acetate, the highest preference was for N-acetyl-9-O-acetylneuraminic acid, followed by N-acetyl-4-O-acetylneuraminic acid. Other primary acetyl esters such as 6-O-acetylated D-glucose and 2-acetamido-2-deoxy-D-mannose were not hydrolyzed. The 9-O-acetyl derivative of the naturally occurring unsaturated sialic acid 2-deoxy-2,3-didehydro-N-acetylneuraminic acid, however, is a substrate for this esterase. Whereas N-acetyl-9-O-acetylneuraminic acid as a component of sialyllactose is nearly as well hydrolyzed as the corresponding free sialic acid, O-acetylated sialoglycoconjugates with high molecular weights (mucins, serum glycoproteins, gangliosides) are not hydrolyzed by this esterase. N-Acetylated sialic acids are better substrates than the analogous N-glycoloyl derivatives. Esterification of the carboxyl function of sialic acids prevents the action of the esterase on the O-acetyl groups. The enzyme has no carboxyl esterase or amidase activity, and does not act on acetylcholine. It hydrolyzes almost exclusively acetyl esters. Inhibition studies suggest that it has a catalytically active serine residue.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylesterase↗
PubMed1989

[Requirements for the effectiveness of disinfectants for the food-processing industry].

An effective disinfection depends on the tested efficiency of commercial products. The recommendations given by producers must be justified by facts. As no official registration procedure exists in Germany, the results obtained by voluntary testing institutions of scientific or branch-specialized associations have to be considered. A remarkable progress could be achieved in that field in the last years. Established were precisely prescribed test methods for disinfectants for (1) hospitals, kitchen areas included, by the DGHM (Deutsche Gesellschaft für Hygiene und Mikrobiologie); (2) processing areas for food of animal origin, kitchen areas also included, by the DVG (Deutsche Veterinärmedizinische Gesellschaft); (3) the beverage, especially the brewing industry by the MEBAK (Mitteleuropäische Brautechnische Analysen-Kommission); and (4) milk producing establishments by the DLG (Deutsche Landwirtschaftsgesellschaft). Each test method requires a different volume of procedures. This paper demonstrates by comparing the test factors which results may be achieved. Also taken into consideration were the methods prescribed by AFNOR (French Standardizing Organization) and by a Commission of the European Council. A disinfectant to be applied in the food industry should meet the following requirements: it should be (a) effective under application periods shorter than usually recommended for hospital areas or animal husbandry; (b) tested on less and heavier protein-loaded areas; (c) tested also under low-temperature conditions; (d) classified by groups of food products, in order to minimize the amount of substance applied to avoid unnecessary residues. The most comprehensive results may be obtained by the methods of the DGHM, DVG and MEBAK. The most specific data are provided in the DVG-list, the DGHM-list offers a somewhat reduced amount of specifics and the DLG-list is limited only to that informations which serve as basis for a quality seal. More coordination between the different testing and evaluation procedures would be appropriate in order to allow a comparison of the same products judged for different areas of application. An official test proceeding seems not necessary in Germany as enough reliable data are available from the above indicated institutions.

Animals↗
PubMed1989

[Glucuronidase detection and indol capillary test as reliable rapid identification procedures for the detection of E. coli in foods--toxinogenic strains included].

The fluorogenic beta-D-Glucuronidase test, together with an Indol-capillary test for rapid identification of E. coli, were proved with 60 toxinogenic, 335 nontoxinogenic wild-type strains, and 87 other gram-negative isolates from food. With a sensitivity of 96.5% and a specificity of 95.6%, the fluorogenic assay can be recommended as a reliable method for presumptive determination of E. coli. For confirmation, a time-, material- and labour-saving Indol-capillary test with simultaneous demarcation of fluorescence-positive Salmonella spp. should be carried out. This includes enterotoxigenic E. coli as well, with the exception of some fluorescence-negative Verotoxin-producing strains. As the primary cultivation medium the Plate-count-Monensin-KCl-Agar supplemented with 50 micrograms/ml 4-methyl-umbelliferyl-beta-D-glucuronide (PMK-MUG) can be recommended. Not suitable appear such media containing lactose due to acidification, while metabolizing the carbohydrate. This may significantly reduce or extinguish the fluorescence. The procedure recommended here permits also a reliable determination of lactose-negative E. coli-biotypes.

Bacteriological Techniques↗
PubMed1988

[Detection and characterization of a levansucrase and a sucrase in Pseudomonas syringae pv. phaseolicola].

Pseudomonas syringae pv. phaseolicola, a plant pathogenic pseudomonad, possesses two sucrose-splitting enzymes, a levansucrase and a sucrase. The levansucrase is found both extracellularly and intracellularly, and enzyme synthesis is independent of the carbon source. In addition to levansucrase, cells grown on sucrose contain a sucrase. The two sucrose-splitting enzymes differ in their optimum pH value and optimum temperature as well as in their substrate specificities.

Hexosyltransferases↗
PubMed1988

The effects of two mutations connected with chromatin functions on female germ-line cells of Drosophila.

We have studied the developmental effects of two dominant suppressor mutations of position-effect variegation mutations on female germ-line cells. Su-var(2)1(01), which has been shown to affect chromatin structure though altering histone deacetylation, and Su-var(3)3(03) are recessive female steriles and zygotic lethals in the presence of butyrate or an additional Y chromosome. We have analysed mosaic females with mutant germ-line and normal soma and concluded that intact functions of the Su-var(2)1 and the Su-var(3)3 genes are required for development of both the soma and the germ-line and that as indirect evidence suggest, their maternally provided products are needed for normal embryonic development. It is suggested that there is possibly a common control of chromatin structure and gene expression in the soma, female germ-line and embryonic cells of Drosophila.

Animals↗
PubMed1988

Sialate O-acetylesterases: key enzymes in sialic acid catabolism.

Sialate 9(4)-O-acetylesterases (EC 3.1.1.53) have been isolated from equine liver, bovine brain and influenza C virus. In this latter case, the esterase represents the receptor-destroying enzyme of the virus. The kinetic properties of these enzymes were determined with Neu5,9Ac2 and in part with 4-methylumbelliferyl acetate and Neu5,9Ac2-lactose. The Km values vary between 0.13 and 24 mM and the Vmax values from 0.55 to 11 U/mg of protein. The pH optima are in the range of 7.4-8.5, the molecular masses at 56,500 and 88,000 Da. In addition to a fast hydrolysis found for aromatic acetates, such as 4-methylumbelliferyl acetate or 4-nitrophenyl acetate, N-acetyl-9-O-acetylneuraminic acid is de-O-acetylated at the highest relative rate. Other substituents at the 9-position, such as lactoyl residues, or acetyl groups at other positions within the side chain are not hydrolyzed. Neu4,5Ac2, however, is a substrate for all 3 enzymes. The hydrolysis rates of this ester function, which renders sialic acids resistant to the action of sialidases, vary from 3 to 100% relative to Neu5,9Ac2. Whereas Neu5,9Ac2-lactose is hydrolyzed by the bovine and viral esterases, other O-acetylated sialic acids in glycoconjugates are only attacked by the enzyme from influenza C virus and not by that from bovine brain. The esterase from horse liver also releases 4-O-acetyl groups from equine submandibular gland mucin. By incubation with appropriate substrates and inhibition studies, carboxylesterase, amidase and choline esterase activities were excluded, as well as the cleavage of other acyls, e.g., butyryl groups. Thus, the enzymes investigated belong to the acetylesterases.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylesterase↗
PubMed1988

Isolation and characterization of sialate 9(4)-O-acetylesterase from influenza C virus.

An esterase was isolated from influenza C virus with a specific activity from 1.7-5 U/mg protein, and its substrate specificity was tested with various naturally occurring O-acylated sialic acids, synthetic carbohydrate acetates, and other esters. The enzyme hydrolyses only acetic acid esters at significant rates. The non-natural substrates 4-methyl-umbelliferyl acetate, 4-nitrophenyl acetate, and alpha-naphthyl acetate are cleaved at highest hydrolysis rates, followed by the natural substrate N-acetyl-9-O-acetylneuraminic acid. The esterase also acts on N-glycoloyl-9-O-acetylneuraminic acid and, much slower, on N-acetyl-4-O-acetylneuraminic acid; N-acetyl-7-O-acetylneuraminic acid is not hydrolysed. 2-Deoxy-2,3-didehydro-N-acetyl-9-O-acetylneuraminic acid is also a substrate for this enzyme, however, 6-O-acetylated N-acetylmannosamine and glucose are not. Esterification of the carboxyl function of sialic acids strongly reduces or prevents esterase action on O-acetyl groups. The carboxyl ester is not hydrolysed. The relative cleavage rates also depend on the type of the non-sialic acid part of the molecule. N-Acetyl-9-O-acetylneuraminic acid as component of sialyllactose and rat serum glycoprotein shows hydrolysis rates close to the free form of this sugar, while acetyl ester groups of bovine submandibular gland mucin and rat erythrocytes are hydrolysed at slower rates. Gangliosides and 4-O-acetylated glycoproteins are no substrates for the purified enzyme. A slow hydrolysis is observed by incubation of 9-O-acetylated GD1a with intact influenza C viruses. As other natural acetyl esters (acetyl-CoA and acetylthiocholine iodide) are not hydrolysed, the enzyme can be classified as sialate 9(4)-O-acetylesterase (EC 3.1.1.53).

Acetylesterase↗
PubMed1988

[Multicenter survey related to the frequency of positive patch tests with mercury and thiomersal].

A multicentric study concerning the frequency of positive allergic patch test reactions to mercury and to thiomersal has been conducted in France and in Belgium among 2,000 adult patients submitted to routine patch testing. 73 (3.6 p. 100) patients had a positive patch test to mercury and 47 (2.3 p. 100) to thiomersal, 22 (1.1 p. 100) reacted positively to both mercurials. These high figures are most probably in relation with a broad use of mercurials in both countries, as antiseptics as well as preservative agents in topical drugs. They lead to a careful use of mercurials, which have to be avoided when they can be advantageously replaced by other antiseptics or preservative agents. As far as cosmetics are concerned, the use of mercurials (chemical nature and concentration) is restricted by a Recommendation of the European Council.

Adult↗
PubMed1987

Angiotensin evokes in polyploid rat glioma cells hyperpolarization-depolarization responses and cross-desensitization with bradykinin.

Angiotensins I, II and III induced a hyperpolarizing response of up to 1 min duration followed by a depolarizing response of up to 4 min when applied by pressure pulses or iontophoresis to polyploid rat glioma cells C6-4-2. The hyperpolarization (depolarization) was associated with a 50% decrease (no measurable change) in membrane resistance. The reversal potential (ca.-90 mV) of the hyperpolarization most likely points to an increase K+ conductance. Cells desensitized to angiotensins on application of high doses of either angiotensins or bradykinin.

Angiotensin II↗
PubMed1987

[Demonstration of an NAD-dependent 6-phosphogluconate dehydrogenase in Pseudomonas syringae pv. phaseolicola].

Crude extracts from cells of Pseudomonas syringae pv. phaseolicola, a fluorescent pseudomonad, when grown on glucose contain a NAD-linked 6-phosphogluconate dehydrogenase. The reaction of the enzyme, which produces 14CO2 from 1-14C-6-phosphogluconate, is not inhibited by NaF, a potent inhibitor of the Enter-Doudoroff (ED) pathway enzyme 6-phosphogluconate dehydratase. In the presence of phosphate or arsenate ions the NAD-linked glyceraldehyde-3-phosphate dehydrogenase reacts with glyceraldehyde-3-phosphate which, in the ED pathway, is produced from 6-phosphogluconate and overlaps the 6-phosphogluconate dehydrogenase reaction. Only a small proportion of glucose is metabolized via the 6-phosphogluconate dehydrogenase/oxidative pentose phosphate pathway.

Kinetics↗
PubMed1987

Modifiers of position-effect variegation in the region from 86C to 88B of the Drosophila melanogaster third chromosome.

Four dominant suppressor and one enhancer of variegation loci were mapped in the polytene chromosome region extending from section 86C to section 88B of the Drosophila melanogaster third chromosome using a set of deficiencies. The suppressor locus Su-var(3)14 maps in 86CD, Su-var(3)13 in 86F4-7, Su-var(3)6 in 87B4-7 and Su-var(3)7 in 87E4-5. The enhancer locus E-var(3)3 maps in 87E12-F11. Su-var(3)13, Su-var(3)6 and Su-var(3)7 are also defined by point mutant alleles originally identified by other criteria (Reuter et al. 1986). Duplications covering the suppressor loci Su-var(3)14, Su-var(3)13, Su-var(3)6 and Su-var(3)7 were found to reduce considerably the haplo-abnormal effect of heterozygous point mutants of the corresponding loci. One suppressor locus, Su-var(3)7, maps within a region which has previously been cloned. The positions of deficiency breakpoints delimiting the suppressor locus indicate that all the necessary sequences for its function are located within 10 kb of cloned DNA.

Animals↗
PubMed1987

Characterization of two ornithine carbamoyltransferases from Pseudomonas syringae pv. phaseolicola, the producer of phaseolotoxin.

Two ornithine carbamoyltransferases (OCT 1 and OCT 2) were isolated from Pseudomonas syringae pv. phaseolicola and purified by precipitation with ammonium sulfate, heat denaturation, chromatography on DEAE-Sephadex A-50 and Sephadex G-200. Molecular weights of both enzymes: 110,000; optimal activity: pH 8.5 to 9.5 (OCT 1), pH 8.4 (OCT 2); apparent Km for ornithine: 7 X 10(-4) (both enzymes); apparent Km for carbamoyl-phosphate: 7 X 10(-4) (OCT 1), 2.8 X 10(-3) (OCT 2). Both enzymes possess only an anabolic function. OCT 1 is highly inhibited by low concentrations of phaseolotoxin and Orn-P(O)(NH2)-NH-SO3H, OCT 2 is insensitive to both compounds. The inhibition of OCT 1 is reversible.

Exotoxins↗