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Biomedical subjects

H Persson

Publications and source records attributed to H Persson.

At least 343 records · Page 19Linked to original sources
PubMed1979

A DRB (5,6 dichloro-beta-D-ribofuranosylbenzimidazole)-resistant adenovirus mRNA.

5,6-Dichloro-beta-D ribofuranosyl benzimidazole (DRB) inhibits transcription from the major late adenovirus promoter, located on the r-strand at map position 16.3 on the viral genome. 100-500 nucleotides long RNA chains with capped 5'-termini are transcribed from this promoter in the presence of 70 muM DRB. Synthesis of the mRNA for polypeptide IX which is unspliced and maps on the r-strand between positions 9.7 and 10.9 appears, however, to be DRB-resistant although it is transcribed by polymerase II and capped. Translatable mRNA for polypeptide IX is synthesized in the presence of DRB while the mRNAs for the other viral structural proteins are not synthesized. This differential DRB-inhibition of polymerase II transcription suggests either that short mRNAs may escape inhibition or that unspliced mRNAs are insensitive to the drug.

Adenoviruses, Human↗
PubMed1979

Purification of RNA-DNA hybrids by exclusion chromatography.

A simple method for selection of RNA-DNA hybrids has been developed and applied to the purification of adenovirus-specific messenger RNA. Cytoplasmic RNA prepared from adenovirus type 2 (ad2)-infected HeLa cells or from an ad2-transformed rat cell line was hybridized in solution to the complementary strands of ad2 DNA. The hybridization mixture was subsequently fractionated by chromatography on a Sepharose 2B column. The intact probe DNA as well as the RNA-DNA hybrids are excluded from the gel matrix and elute with the void volume. Nonhybridized RNA, in contrast, is included into the gel matrix and elutes as a broad peak well separated from the excluded fractions. Fractions corresponding to the void volume, were collected and the RNA-DNA hybrids were denatured in 90% formamide. The selected RNA was separated from the DNA by affinity chromatography on poly(U)-Sepharose. Restriction endonuclease fragments of DNA with a large enough size to make them excluded from the agarose column were also used for hybridization. In these experiments hybridizations were carried out under conditions which would allow R-loop formation (Thomas, M., White, R.L., and Davis, R.W. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 2294-2298) and the hybridized RNA was separated from unhybridized RNA by Sepharose chromatography. The validity of the method was demonstrated by programming an in vitro protein-synthesizing system with selected RNA.

Adenoviruses, Human↗
PubMed1979

Purification and characterization of an early glycoprotein from adenovirus type 2-infected cells.

An adenovirus type 2 early glycoprotein with an apparent molecular weight of 19,000 (E19K) in sodium dodecyl sulfate-polyacrylamide gels has been extensively purified. Purification involved detergent solubilization of membrane fractions from infected cells, followed by affinity chromatography on a lectin column and DEAE-Sephadex chromatography. The purified material contained three polypeptides (E40K, E19K, E17.5K), with approximately 90% of the material in the E19K moiety. All three polypeptides yielded identical tryptic peptide maps. The E19K polypeptide contained glucosamine as revealed by [3H]glucosamine labeling of infected cells and amino acid analysis of the purified protein. Immunoprecipitation with a monospecific antiserum showed that the E19K polypeptide started to be synthesized at 2 h, with a maximal rate at 4 h after infection. It was also synthesized at a low rate late in the infectious cycle (12 to 24 h postinfection). Immunoprecipitation from three adenovirus type 2-transformed hamster embryo cell lines and two adenovirus type 2-transformed rat cell lines revealed that one of the hamster cell lines (ad2HE4) and one of the rat cell lines (A2T2C4) expressed this protein.

Adenoviruses, Human↗
PubMed1978

Molecular association between transplantation antigens and cell surface antigen in adenovirus-transformed cell line.

A rat cell line (A2T2C4) transformed with adenovirus type 2 elicited cytotoxic T lymphocytes in syngeneic rats. Cytotoxicity was abolished by a rabbit antiserum directed against the major histocompatibility (AgB) antigens and by a syngeneic rat antiserum raised against the virus-transformed cell line. The syngeneic antiserum immunoprecipitated surface proteins with apparent molecular weights of 45,000, 19,000, 17,000, and 12,000 from the A2T2C4 cells but it displayed no reactivity against primary rat fibroblasts and spleen cells. The rabbit antiserum against AgB antigens precipitated a 19,000-dalton component from the A2T2C4 cells which was not observed in primary rat fibroblasts. Sequential immunoprecipitation revealed identity between the major polypeptides recognized by the two antisera. Because the rabbit anti-AgB antigen serum was specific for the transplantation antigen subunits and because the syngeneic rat antiserum against the A2T2C4 cells failed to react with the AgB antigens in normal cells, it is concluded that the 19,000-dalton component is coprecipitated with the AgB antigens. Antisera directed specifically against beta2-microglobulin and the alloantigenic AgB antigen subunit also coprecipitated the 19,000-dalton component. These results indicate that the AgB antigen subunits form a ternary complex with a virus-coded protein on the surface of the virus-transformed A2T2C4 cells. This molecular complex may be recognized by the cytoloytic T lymphocytes

Adenoviruses, Human↗
PubMed1978

Modulation of immune responses in newborn and adult mice by interferon.

Interferon was found to have both suppressive and enhancing effects on the antibody response in newborn and adult mice. Evidence was obtained that these effects are primarily evoked during the initial steps controlling cell proliferation. Stimulation of thymus and spleen cells with a T-cell mitogen was enhanced by low doses and suppressed by high doses of interferon. Treatment of parental spleen cells with interferon before injecting them into immunized F1 hybrid mice resulted in an enhanced allogeneic effect. These results are compatible with the hypothesis that interferon affects T cells and has an immunoregulatory role, either by inhibiting the action of suppressor cells or by promoting immunological maturation.

Animals↗
PubMed1978

Viral DNA sequences and gene products in hamster cells transformed by adenovirus type 2.

Complementary strand-specific adenovirus DNA of full length or from endonuclease BamHI fragments was used as a probe to estimate the fractional representation and abundance of viral sequences in five hamster cell lines (Ad2HE1-5) transformed with UV-inactivated adenovirus type 2. The fraction of the viral genome present in the five transformed cell lines varied from 44% in the Ad2HE5 cell line to 84% in the Ad2HE3 cell line. The number of viral DNA copies per diploid cell equivalent ranged from 1.8 in the Ad2HE1 line to 7.1 in the Ad2HE4 line. In vivo labeling with [35S]methionine followed by immunoprecipitation with an antiserum against adenovirus type 2 early proteins revealed virus-specific polypeptides with molecular weights of 42,000 to 58,000 in extracts from all five hamster cell lines. Several other early viral polypeptides were detected in some of the adenovirus type 2-transformed hamster cell lines.

Adenoviruses, Human↗
PubMed1978

Purification and characterization of an early protein (E14K) from adenovirus type 2-infected cells.

One adenovirus type 2 (Ad2) early protein, with an apparent molecular weight of 14,000 in sodium dodecyl sulfate-polyacrylamide gels (E14K), was purified to homogeneity. Purification involved fractionation of cytoplasmic extracts, precipitation at low pH, and DEAE-cellulose, phosphocellulose, and hydroxylapatite chromatography. The yield was around 12 microgram of purified protein per 10(9) HeLa cells. The two Ad2 DNA binding proteins with molecular weights of 75,000 and 45,000 (E75K and E45K) were purified by the same procedure. Tryptic peptide analyses indicated that the E14K protein is unrelated to the DNA binding proteins. The purified E14K protein has a high content of basic amino acids and a sedimentation coefficient of 5.5S in the native state, corresponding to a molecular weight of around 95,000. Pulse-chase experiments suggest that the E14K polypeptide is a primary translation product. Immunoprecipitation with a monospecific antiserum against the E14K protein revealed that it is exclusively localized in the cytoplasm of infected cells. E14K started to be synthesized at 2 hpostinfection, with a maximal rate of synthesis at 4 to 6 h postinfection. Immunoprecipitation of cell extracts from four different Ad2-transformed hamster embryo cell lines revealed that only one (Ad2HE4) of them expresses this protein. The adenovirus-simian virus 40 hybrid virus (Ad2ND1) does not express this protein, suggesting that the gene for the E14K protein is located in the part of the Ad2 genome which is deleted in this hybrid virus.

Adenoviruses, Human↗
PubMed1977

Differentiation of cardiac chronotropic and inotropic effects of beta-adrenoceptor agonists.

The relative inotropic and chronotropic activity of beta-adrenoceptor agonists was studied in the noradrenaline-depleted, anaesthetized cat. Terbutaline, a selective beta2-adrenoceptor agonist, gave at a certain dose a more pronounced chronotropic than inotropic response, while a new beta1-selective adrenoceptor agonist (-)-H 80/62 produced the same degree of chronotropic and inotropic stimulation. The results indicate that there is some difference between the beta-adrenoceptors in the sinus node mediating chronotropic stimulation and beta-adrenoceptors in the ventricular myocardium mediating stimulation of the contractile force. It has been shown that there are both beta1- and beta2-adrenoceptors in the heart (Carlsson et al., 1972). In the light of this finding it is hypothetized that there are differences in the relative distribution of beta1- and beta2-adrenoceptors in the sinus node and in the myocardium. Athough beta1 is the predominant type of beta-adrenoceptor in both regions, the beta1:beta2 concentration ratio seems to be higher in the myocardium, than in the sinus node.

Adrenergic beta-Agonists↗
PubMed1977

Effect of substance P on pulmonary resistance and dynamic pulmonary compliance in the anaesthetized cat and guinea-pig.

The effect of substance P, acetylcholine, and histamine on pulmonary resistance (RL) and on pulmonary dynamic compliance (CDYN) was studied in the anaesthetized cat and guinea-pig. In the anaesthetized guinea-pig, substance P (0.1-1.0 microgram/kg) acetylcholine (1.0-10 microgram/kg), and histamine (1.0-10.0 microgram/kg) produced a dose-dependent increase in RL and decrease in CDYN. In the anaesthetized cat, the effect of substance P was weak on both RL and CDYN, whereas histamine (5-50 microgram/kg) produced a dose-dependent increase in CDYN, but the effect on RL was weak. The effect of acetylcholine was qualitatively the same as in the anaesthetized guinea-pig but about 10 times less effective.

Acetylcholine↗
PubMed1977

In vitro translation with adenovirus polyribosomes.

Polyribosomes isolated from adenovirus type 2 (Ad2)-infected HeLa cells late in productive infection can be used for translation in cell-free systems. At least eight viral polypeptides are synthesized, including the precursors to virion polypeptides VI and VII. Separation of polyribosomes by zonal rate centrifugation followed by translation in a cell-free system reveals a correlation between the sizes of the polyribosomes and the polypeptides synthesized. The cell-free extracts incorporate amino acid linearly for only 10 min and show little or no capacity to reinitiate protein synthesis. The elongation efficiency measured as the number of amino acids incorporated per ribosome in 20 min is low, ranging from 10 to 100. The maximum chain elongation rate is estimated to be 10 to 20 amino acids per min. The limited elongation has been used to assess the relative concentration of mRNA's engaged in translation.

Adenoviruses, Human↗