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Biomedical subjects

A E Berman

Publications and source records attributed to A E Berman.

At least 37 records · Page 2Linked to original sources
PubMed1980

[Content and properties of different classes of membrane-bound polyribosomes during embryogenesis in chickens].

The quantitative ratio, chemical composition and sedimentation properties of three polyribosomal fractions (free polyribosomes and polyribosomes tightly and loosely bound to the endoplasmic reticulum) isolated from chicken embryos of different age were studied. The fraction of polyribosomes loosely bound to the membranes was obtained from the total preparation of membrane-bound polyribosomes by treatment with high ionic strength solutions. It was found that the polyribosomes loosely bound to the membranes and free polyribosomes possess similar chemical composition and sedimentation properties. All the fractions studied were characterized by a much higher polyribosomal content as compared to the 80S monomers. In the course of embryogenesis the amount of polyribosomes loosely bound to the membranes is decreased, whereas that of tightly bound ones is increased. These data are indicative of an enhanced synthesis of secreted proteins, particularly collagen, on tightly bound polyribosomes during embryogenesis in chicken.

Animals↗
PubMed1979

[Biosynthesis of collagen and other proteins on tightly and loosely bound polyribosomes from chick embryos].

Free polyribosomes and polyribosomes bound to endoplasmic membranes were isolated from 10-day-old chick embryos by differential centrifugation. The tightly and loosely bound polyribosomal fractions were isolated from the membrane-bound polyribosomes using 0,5 M KCl. The synthesis of collagen and non-collagen proteins on the polyribosomes were studied in a homologous cell-free system. It was shown that the polyribosomes tightly bound to the membranes possess a lower protein-synthesizing activity as compared to free and loosely bound polyribosomes. The amount of bacterial collagenase-cleaved polypeptides in the protein product synthesized on the polyribosomes tightly and loosely bound to the memranes and on free polyribosomes is 31, 23 and 9%, respectively. The data obtained suggest that the loosely bound polyribosomes are actively involved in collagen synthesis and that this fraction is not a contamination of free polyribosomes in the preparations of totally bound polyribosomes. The role of tightly and loosely bound polyribosomes in the formation of the membrane polyribosomal complex is discussed.

Animals↗
PubMed1978

[Biospecific chromatography of poly(A)-containing RNA on poly(U)-Sepharose].

It is shown that in addition to specific binding of polyadenylic sequence with poly(U), the chromatography of poly(A)-containing RNAs on poly(U)-Sepharose is accompanied by nonspecific irreversible adsorption of polynucleotides on Sepharose gel. This disadvantage may be overcome by establishing optimal BrCN/Sepharose rations during Sepharose activation and by many-fold treatment of poly(U)-Sepharose with ethanolamine immediately before chromatography of RNAs. It was also found that the efficient separation of poly(A+)-RNA preparations from poly(A-)-RNAs is achieved only after double chromatography of RNA on poly(U)-Sepharose. The amount of poly(A+)-RNA in total RNA preparations isolated from bound polyribosomes of 10-day-old chick embryos is equal to 1%. Data from PAAG gel electrophoresis are indicative of the lack of degradation and high heterogeneity of the preparations under study.

Chemical Phenomena↗
PubMedDate not supplied

[The role of alphavbeta3 integrin in changes of the invasive phenotype in CP-transformed fibroblasts with multiple drug resistance].

A line of Syrian hamster RSV-ransformed fibroblasts having resistance to a number of cytostatics was shown to differ from the parental drug-sensitive line by an extremaly low expression of the integrin alpha v beta 3. In vitro invasive activity of the drug-resistrant cells appeared to be lower than that of their drug-sensitive counterparts. The role of integrin alpha v beta 3 in malignant phenotype and multiple drug resistance of tumor cells is discussed.

Animals↗
PubMedDate not supplied

[Determination of procollagen type III aminopropeptide by a solid phase method using antibodies conjugated with peroxidase or protein A labelled with radioactive iodine].

A solid-phase assay was developed for estimation of procollagen III aminopropeptide which involved both immunoenzymatic and radioimmune procedures. The assay did not require the iodine-labelled aminopropeptide, while content of the antigen was estimated using the conjugate of secondary antibodies and peroxidase or iodine-labelled protein A. Substitution of the protein A for the antibodies conjugate and peroxidase enabled to abolish the radioactive materials use.

Animals↗
PubMedDate not supplied

[Antioxidants in malignant neoplasms in humans and animals].

This review is devoted to the role of low molecular weight antioxidants and antioxidant enzymes in cancerogenesis. The data on accumulation of lipid-soluble and water-soluble antioxidants in a number of malignant human and experimental tumors especially in the renal cell carcinoma tissues are analyzed. A possibility is discussed concerning the pro- and anticarcinogenic effects of the abundant tumor content of antioxidants. Implication of antioxidants in tumor resistance to chemotherapeutic drugs and ionizing radiation is discussed.

Animals↗
PubMedDate not supplied

[Biosynthesis of collagen and non-collagen proteins on free and bound polysomes from chick embryo].

Synthesys of collagen and non-collagen proteins was investigated in a cell-free system in the presence of free and bound polysomes isolated from chick embryos. Of total radioactive proteins synthesized on bound and free polysomes the amount of peptides digested by bacterial collagenase comprised 25-40% and 5-7% respectively. These data showed that collagen was predominantly synthesized by bound polysomes. Free polysomes were found to be much more active than bound ones in non-collagen protein synthesis. When bound polysomes detached from membranes by detergent treatment were incubated in a cell-free system, a release of non-collagen proteins into the incubation medium increased sharply, but the release of collagen peptides was as negligible as in the case of untreated polysomes. Kinetic studies of collagen synthetizing activity of polysomes bound to or detached from membranes suggested the role of endoplasmic membranes in stabilizing collagenous polysomes.

Animals↗
PubMedDate not supplied

[Fibronectin fragmentation unmasks the activity stimulating DNA and RNA biosynthesis in granulation tissue cells in vitro].

Human blood plasma fibronectin decreased slightly the incorporation of precursors into nucleic acids of granulation tissue culture cells. A slight fragmentation of fibronectin, where the fragments with 180-200 kD molecular mass were developed, led to occurrence of the activity 2-fold stimulating the DNA synthesis. After more effective proteolysis using plasmin and trypsin the stimulating effect of fibronectin fragments on synthesis of nucleic acids maintained and constituted 165 +/- 12% and 127 +/- 7% for DNA and RNA, respectively.

Animals↗
PubMedDate not supplied

[Isolation and purification of collagen proteins using biospecific chromatography on a sorbent with collagen-binding fragment of fibronectin].

A new procedure is described for isolation of collagens from various preparations containing small amounts of these proteins. The procedure is based on specific affinity of collagens of various types to one of peptide fragments of fibronectin--collagen-binding peptide (CBP). Collagens were isolated after single-step chromatography of tissue homogenate on the sorbent containing immobilized CBP. High specificity and reproducibility of the procedure was shown when various preparations were used: chicken embryo proteins with total radioactive label. Proteins synthesized in fibroblast culture; polypeptides synthesized in cell-free system of protein synthesis.

Animals↗
PubMedDate not supplied

[Characteristics of collagen preparations labelled in vitro by 14C-acetic anhydrides. Their use for the determination of collagenase activity and as radioactive markers].

A modified procedure in developed for acetylation by means of 14C-acetic anhydride of highly purified collagen I preparations. The acetylated collagen exhibited high specific radioactivity and was effectively hydrolyzed by bacterial collagenase. The 14C-acetylated collagen was used as a radioactive marker in electrophoretic analysis of labelled proteins.

Acetates↗
PubMedDate not supplied

[Functional characteristics of two membrane-bound polysome fractions from chick embryos].

Among various membrane-bound polyribosomes from chicken embryos the polyribosomes loosely bound with membranes proved to be highly active in synthesis of total proteins as well as of collagens in vitro. These data suggest that polyribosomes loosely bound with membranes were not an impurity of free polyribosomes in the total preparation of the membrane-bound polyribosomes. These polyribosomes constituted a definite class of polyribosomes active in the synthesis of secreted proteins (i.e. of collagen). In polyribosome fractions identified by their size (monosomes, light and heavy polyribosomes) all the three fractions of loosely-bound polyribosomes as well as light and heavy fractions of tightly-bound polyribosomes were active in synthesis of total proteins. Differences between tightly-and loosely-bound polyribosomes were noted also in studies of cell-free synthesis of collagen proteins. Heavy fractions of tightly-bound polyribosomes were the most active in synthesis of these proteins, light fractions were less active and monosomes did not exhibit any collagen-synthesizing activity. Only monosomes of loosely-bound polyribosomes were responsible for the synthesis of collagen. Polyribosomes loosely-bound with membranes appear to participate at early steps of membrane-polyribosome complex formation.

Animals↗