[Metabolism of hemoglobin A1. No effect of an acute glucose load on the hemoglobin A1 titer in normal subjects].
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Biomedical subjects
Publications and source records attributed to E Neuzil.
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The authors describe a new method of cholesterol determination, using the intense blue color given by interaction with 2,3-naphthalenedicarboxaldehyde in a sulphoacetic medium. The degree of precision of the method, as well as its reproducibility are discussed; a good correlation of the new method with two classical techniques, the colorimetric method of Liebermann and the enzymatic method, is observed. The high sensitivity and the specificity of the colour reaction allow the choice of the method for a direct determination of serum cholesterol using a 10 microliter sample.
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A comparative study of the tyrosinase-tyrosine reaction, using both oxygen-consumption determination and spectrophotometric methods, shows that hydrazine derivatives inhibit melaninogenesis at different steps.
The complete amino acid sequence of the alpha chain from the badger (Meles meles) haemoglobin was elucidated using conventional methods chiefly performed on tryptic peptides separated by peptide "mapping" and comparison with human alpha chain. Sixteen differences were noted between the alpha chain of badger and man. Phylogenetic aspects and three-dimensional structure requirements are discussed.
Microiontophoretic applications of DL-2-amino-3-phosphonopropionic, DL-3-amino-4-phosphonobutyric, aminomethylphosphonic, 2-aminoethylphosphonic and 3-aminopropylphosphonic acids in the course of extracellular recordings of central neurons in the Rat resulted in effects which appeared similar to those observed with their carboxylic analogs. The involvement of the same post-synaptic receptors is suggested.
alpha-Hydrazinophloretic acid, the hydrazino analogue of tyrosine, was shown to behave as a competitive inhibitor of tyrosinase. Some closely related compounds, especially the hydrazino analogue of phenylalanine as well as other hydrazine derivatives, will also inhibit the enzyme, but in these cases, the inhibition observed belonged to the non-competitive type.
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Adding zinc or cobalt sulphate into synthetic culture media of Pseudomonas aeruginosa was followed by partial or total inhibition of pyocyanine production, varying with the nature of the chemical source of phosphorus. An antagonism between Zn2+ and Co2+ ions was shown.
3-Aminopropylphosphonic acid and 2-(beta-alanyl-amino)-ethylphosphonic acid can be used by Pseudomonas aeruginosa as a phosphorus source. Both compounds undergo a biodegradation through the cleavage of the C--P bond, without any modification upon the amino or amino-groups of the substrates.
Badger (Meles meles) haemoglobin was purified by paper electrophoresis and converted into globin. Chain separation was carried out on a CM-cellulose column in the presence of 8 M urea. The beta-chain was aminoethylated, purified by gel filtration and submitted to tryptic digestion. A fingerprint obtained with the enzymic digests showed 17 distinct ninhydrin-positive spots from which 20 pure peptides were isolated by further electrochromatographic separations. These peptides were sequenced using Dansyl-Edman and Ptc-Edman degradation techniques. The presence of amide residues was confirmed after aminopeptidase M hydrolysis. Taking human haemoglobin beta-chain as a model, the covalent structure could be completely resolved without the help of any further overlapping technique. The following substitutions were noted (badger/human, position): Ala/Pro5, Ser/Ala13, Tyr/Phe41, Asp/Glu43, Ser/Ala70, Glu/Asp73, Lys/Ala76, Asn/His77, Lys/Thr87, Lys/Arg104 and Gln/Pro125. A comparison with other haemoglobin beta-chains already sequenced shows a greater similarity with dog haemoglobin, the only example of beta-chain of known structure in the order of Carnivores.
2-Aminoethylphosphonic acid (ciliatine) can be used as a source of phosphorus or nitrogen by Pseudomonas aeruginosa. The conditions of its uptake have been investigated. The transport is inducible by ciliatine itself or by its homologue, 3-aminopropylphosphonate, but neither by other phosphonic compounds nor by carboxylic or sulfonic related derivatives. The induction was not suppressed by inorganic phosphate. The transport appears to be an active process, pH and temperature dependent: it requires energy and is dependent on new protein synthesis. The uptake follows Michaelis kinetics. The substrate specificity involved in ciliatine uptake favours the existence of two different transport systems: the first one, inducible by ciliatine, was very sensitive towards different aminophosphonic acids and was competitively inhibited by inorganic phosphate and methylphosphonate; the second transport system, inducible by 3-amino-propylphosphonate, appeared less sensitive towards alpha-aminophosphonic acids and was non competitively inhibited by phosphate and methylphosphonate. No interactions were observed with related aminocarboxylic acids or with taurine. Some molecular structural requirements for the binding of an effector on both permeases are discussed. The regulatory function of inorganic phosphate, the chief breakdown product of ciliatine, is also emphasized.
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1. In vivo this investigation was carried out in order to compare the incorporation into rat lipids of free [1,2-minus 14C]-ciliatine and CMP-[1,2-minus 14C]-ciliatine which is the precursor in phosphonolipid biosynthesis. 2. The incorporation of the radioactivity from CMP-[1,2-minus 14C]-ciliatine took place more rapidly than that from free [1,2-minus 14C]-ciliatine in both liver and kidney. The amount of radioactivity from the CMP-[1,2-minus 14C]-ciliatine incorporated into total liver lipids was about 5 times higher than that incorporated into total liver lipids of rat two hrs after injecting free-[1,2-minus 14C]-ciliatine. 3. The amount of [1,2-minus 14C]-ciliatine incorporated into total liver lipids was 15 and 21 times higher than that incorporated into total kidney lipids of rat two and four hrs after injecting free [1,2-minus 14C]-ciliatine. 4. If the main pathway for the phosphonolipid biosynthesis is via CMP-ciliatine, the rate of phosphonolipid formation from CMP-ciliatine must therefore be higher than that from free-ciliatine. The results obtained here indicate therefore that the main pathway for phosphonolipid biosynthesis is a pathway involving CMP-ciliatine. 5. An unknow compound was detected in the water soluble fraction of the acid hydrolyzate of liver phosphonolipids. This material migrated with the N-trimethyl-derivative of ciliatine on the thin-layer chromatogram. The result shows that there is therefore a possibility of methylation of exogenous ciliatine to the phosphonate analogue of choline in the mammalian body.
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