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Biomedical subjects

J Urban

Publications and source records attributed to J Urban.

At least 145 records · Page 8Linked to original sources
PubMed1980

N-terminal amino acid sequence of proalbumin from inbred buffalo rats.

The sequence of radioactively labelled amino acids at the N-terminus of proalbumin was determined by automated Edman-degradation. [3H] Valine, [3H]phenylalanine or [14C]arginine was incorporated into protein in vivo for a time period of 10 min after injection. Since albumin remains unlabelled during this time period (Urban et al., 1976), separation of proalbumin and albumin was not required for this work. Hence, compared to previous methods, a shorter purification procedure could be used which increased the yield of anti-albumin-precipitable protein and reduced the risk of proteolysis. Microsomes were prepared from livers removed 10 min after injection of the radioactively labelled amino acids. A buffer extract of the acetone-dried powder from these microsomes was chromatographed on DEAE-cellulose. All protein obtained after chromatography which could be precipitated with antiserum to serum albumin was isolated by immunoprecipitation and subsequent separation of the antigen-antibody complex. The sequence of radioactive amino acids in this antigen preparation suggests that about 20-25% of proalbumin possessed at the N-terminus the pentapeptide sequence X-Val-Phe-Arg-Arg- whereas 75-80% contained the hexapeptide sequence Arg-X-Val-Phe-Arg-Arg-.

Albumins↗
PubMed1979

A rat serum glycoprotein whose synthesis rate increases greatly during inflammation.

Crossed immunoelectrophoresis of rat serum demonstrated considerably increased serum concentrations of at least ten different proteins during turpentine-induced inflammation. One protein, which moved during electrophoresis like an alpha 1 globulin, showed a particularly large increase. This protein was purified to homogeneity by ammonium sulfate fractionation followed by chromatography on DEAE-cellulose. Sephadex G-100, and concanavalin A-Sepharose, and finally disc electrophoresis in polyacrylamide gel. It has a molecular weight of 56,000 determined by equilibrium ultracentrifugation. An apparent molecular weight of 68,000 was estimated for the reduced protein by electrophoresis in polyacrylamide gel plus sodium dodecyl sulfate, suggesting that the native protein is composed of a single polypeptide chain. It has an E2801%, 1 cm of 5.2, an isoelectric pH of 4.7, and contains 19% carbohydrate. The protein does not inhibit bovine trypsin or chymotrypsin. Its physical properties and amino acid composition distinguish this protein from all other rat serum proteins hitherto characterized. During acute inflammation, induced 25 h previously, rats incorporated 20 times more [14C]leucine into this particular protein than did normal rats. However, incorporation into total serum protein during acute inflammation increased only slightly. Regardless of whether inflammation was induced by surgical injury or by a subcutaneous turpentine injection, within 48 h the serum concentration of this major acute-phase protein rose from the normal value of 0.46 g/liter to a maximum value of 7.2 g/liter, which constituted 10% of the total serum protein.

Alpha-Globulins↗
PubMed1979

Sister-chromatid exchanges and chromosal breakage in patients treated with cytostatics.

The frequency of structural chromosomal rearrangements and sister-chromatid exchanges (SCEs) was investigated in short-term phytohemagglutininstimulated lymphocyte cultures by means of bromodeoxyuridine substitution and fluorescence plus Giemsa (FPG) staining technique. Both these parameters were significantly increased in patients treated with comparatively low doses of cyclophosphamide, busulphan and adriamycin. The increased SCE rate was proportional to the number of chromosome breaks, the ratio of SCE to breaks being about 100:1. The increase in the SCE number was maintained for several months after the termination of cytostatic therapy, when the conventional analysis of chromosome breaks yielded normal results. Normal SCE values were obtained in two patients treated with low doses of fluorouracil.

Bromodeoxyuridine↗
PubMed1979

Relationship between protein synthesis and secretion in liver cells and the state of the adenine nucleotide system.

Adenine nucleotide levels could be precisely and reproducibly adjusted in liver cell suspensions by partially depleting the ATP pool with D-fructose or glycerol. Thus, it was possible to quantitatively correlate rates of protein synthesis and secretion with intracellular levels of ATP and with derived parameters, such as the adenylate energy charge. Half the maximum rate of incorporation of leucine into protein was observed at an energy charge of 0.80, a ratio of ATP to ADP of 2.6, and an ATP level of 1.05 mumol per g of wet cells. Proteins were secreted with half the maximum rate at an energy charge of 0.85, a ratio of ATP to ADP of 3.1 and an ATP concentration of 1.1 mumol per g of wet cells. Protein secretion did not depend on continued synthesis. Inhibitors of oxidative phosphorylation inhibited protein secretion in addition to protein synthesis, in contrast to observations by other authors on liver slices.

Adenine Nucleotides↗