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Biomedical subjects

D Egger

Publications and source records attributed to D Egger.

52 records · Page 3Linked to original sources
PubMed1986

Production of monoclonal and monospecific antibodies against non-capsid proteins of poliovirus.

Non-capsid poliovirus proteins of the P2 region in extracts of infected cells were solubilized by SDS, separated by PAGE, electroeluted from the gels and used to immunize mice. The sera obtained were rendered monospecific by extensive absorption with proteins from uninfected cell extracts, and the spleen cells of these animals were used to establish antibody-secreting hybridomas. The monoclonal and the monospecific antibodies recognized denatured antigen (proteins 2C, 2BC and P2) in ELISA, immunoblot and immunoprecipitation tests and also combined with the native proteins of the P2 region in immunoprecipitation. In addition, the antibodies could be used successfully for immunofluorescence and electron microscopic immunocytochemistry.

Antibodies, Monoclonal↗
PubMed1986

Exercise induced asthma and endogenous opioids.

Concentrations of endogenous opioid peptides in the plasma are increased during exercise and these substances have been implicated in the pathogenesis of asthma induced by chloropropramide and alcohol in diabetic patients. This work was undertaken to determine whether exercise induced asthma might be mediated by endogenous opioids. Plasma beta endorphin, met-enkephalin, and adrenocorticotrophic hormone (ACTH) concentrations were measured in five asthmatic patients and five normal volunteers breathing cold air during exercise. In four of the patients the effect of an infusion of naloxone on FEV1 was also measured during exercise induced asthma. Exercise produced acute bronchoconstriction in all asthmatics, characterised by a fall in FEV1; whereas no change occurred in normal subjects. There was no difference in plasma met-enkephalin, beta endorphin, and ACTH concentration between the two groups. Infusion of naloxone neither prevented nor worsened exercise induced asthma. These data suggest that endogenous opioids probably do not play a part in the development of exercise induced asthma.

Adult↗
PubMed1986

Electron microscopic immunocytochemistry. Silver enhancement of colloidal gold marker allows double labeling with the same primary antibody.

Electron microscopic sections, immunocytochemically labeled with colloidal gold, can be prepared for double labeling by applying the "EM-silver enhancement" procedure. This method, a photographic, so-called physical, development, increases the size of the gold marker to a predeterminable value and thereby inactivates the anti-species antibody present on the gold grain, thus allowing the labeling of a second antigen with antibody raised in the same species.

Antibodies, Monoclonal↗
PubMed1984

Accumulation of poliovirus proteins in uninfected isolated HEp-2 cell nuclei in vitro.

Poliovirus (type 1, Mahoney) proteins preferentially inhibited in vitro RNA polymerase II activity in uninfected isolated HEp-2 cell nuclei, as demonstrated by electron microscopic autoradiography. Structural integrity of the nuclei and preincubation of nuclei and poliovirus proteins in vitro prior to addition of [3H]-UTP were prerequisites for differential inhibition. During in vitro incubation, [3H]-labeled poliovirus proteins were shown to accumulate in the uninfected isolated nuclei. Similar poliovirus proteins accumulated in the nuclei to higher relative amounts as compared to the outside or were excluded from the nuclei after in vitro incubation, as in intact poliovirus-infected cells. Since the in vitro transcription system of isolated nuclei exhibited two characteristics of poliovirus infection, i.e., preferential inhibition of RNA polymerase II activity and accumulation of poliovirus proteins in the nuclei, it may be useful to study host RNA synthesis inhibition.

Autoradiography↗
PubMed1983

Intracellular distribution of poliovirus proteins and the induction of virus-specific cytoplasmic structures.

In a susceptible cell, enteroviruses induce a vesiculated region (the "virus-induced vesicles") which is both the site of viral RNA synthesis as well as the site referred to morphologically, as the "cytopathic effect." Proteins of poliovirus (type I, Mahoney) were shown to migrate into the region of the virus-induced vesicles of infected HEp-2 cells. Five proteins (P2-5b, P3-4b, P3-6a, P3-7c, P3-9) were found to be associated with the vesicles themselves, either as intrinsic membrane protein (P3-9) or in a soluble form within the vesicles (P3-4b, P3-7c, and, partially, P3-6a) or bound to a DOC-resistant structure (P2-5b and a small amount of P3-6a). Partial inhibition of the cleavage of the viral polyprotein with ZnCl2 was used to alter the viral protein pattern within the cells. The data obtained indicate that P2-5b is the protein responsible for the formation of the virus-induced vesicles.

Carcinoma, Hepatocellular↗
PubMed1982

Establishing generalized, productive verb-noun phrase usage in a manual language system with moderately handicapped children.

Strategies for producing generalized language skills continue to be of considerable interest to those working with severely language-delayed children. Research on generalized instruction-following suggested that strategies employing linguistic elements (verbs, nouns, adjectives, etc.) arranged in systematic combination matrices were successful in producing generalized and novel responses among handicapped children. The efficacy of a training matrix in the development of expressive verb-noun phrase usage was demonstrated. Two of the three students showed considerable gains in trained responses as well as predicted, novel responses, while a third who had much less training, showed some gains. Increases were also found in the overall development of expressive language tests. This approach is discussed in relation to other experimental approaches to language development.

Child↗
PubMed1982

Poliovirus-induced inhibition of host RNA synthesis studied in isolated HEp-2 cell nuclei.

Nuclei isolated from uninfected HEp-2 cells synthesized RNA for 60 to 90 min. The individual RNA polymerase activities were determined by alpha-amanitin differential inhibition and the RNA products characterized by electron microscope (EM) autoradiography and sucrose gradient centrifugation. In nuclei prepared from poliovirus-infected cells, the capacity to synthesize RNA in vitro decreased with time after infection. RNA polymerase II activity (hnRNA synthesis) was preferentially inhibited more than was the polymerase I activity (rRNA synthesis). Poliovirus-infected cytoplasm (S-30) inhibited in vitro RNA synthesis in uninfected nuclei by selectively affecting the polymerase II activity. Selective inhibition of hnRNA synthesis by the crude extracts could be monitored by EM autoradiography directly. Determinations of individual RNA polymerase activities by differential alpha-amanitin inhibition were done only after treatment of the infected cytoplasm with micrococcal nuclease to abolish virus RNA replication. Selective inhibition of hnRNA synthesis depended on preincubation of the nuclei together with the infected cytoplasm, indicating that inhibitory substances from the infected cytoplasm entered the nuclei. Isolated nuclei therefore provide a useful system for studying the nature of the inhibitor(s) and of host RNA synthesis inhibition by picornaviruses.

Cell Line↗
PubMed1982

Accumulation of poliovirus proteins in the host cell nucleus.

Poliovirus (type 1, Mahoney) proteins were transported into the nuclei of HEp-2 cells, as demonstrated by means of electron microscopic autoradiography. Quantitative determinations of the proteins by electrophoresis showed that the relative amounts of precursor proteins (1a, 3b, 1b), of some of the intermediate polypeptides (3a, 3c, 5b, 2), and of one end product (VP1) were higher in the nucleus than in the cytoplasm. Other proteins (VPO, VP2, X, 4, 6a) were found in the same relative amounts in the nucleus as in the cytoplasm, whereas two proteins (VP3 and 6b) were excluded from the nucleus. The findings are discussed in view of the recently demonstrated inhibitory activity exerted by cytoplasmic extracts of poliovirus-infected cells on transcription in isolated nuclei of uninfected cells.

Cell Compartmentation↗
PubMed1978

Differential inhibition of host cell RNA synthesis in several picornavirus-infected cell lines.

Patterns of cellular RNA synthesis during poliovirus (types 1,2 and 3) and mengovirus infections in HeLa, HEp-2, Vero and L-cells were investigated by means of high-resolution autoradiography, kinetics of 3H-uridine incorporation, and sucrose gradient centrifugation. Only mengovirus-infected L-cells showed an early and exponential inhibition of hnRNA and rRNA synthesis. The other cell lines tested, whether infected with polio- or mengovirus, exhibited a slowly and linearly decreasing cellular RNA synthesis, with hnRNA production suppressed completely, although somewhat later than in L-cells, and rRNA synthesis continuing at a gradually reduced rate during the entire viral growth cycle. Locations of cleavage steps of rRNA precursor molecules are discussed.

Autoradiography↗
PubMed1975

A method for distinction between RNA and DNA in aldehyde and osmiumtetroxide-fixed electron microscopic autoradiographs.

A simple method for distinction between RNA- and DNA-containing structures in aldehyde- and osmiumtextroxide-fixed electron microscopic autoradiographs (or ordinary thin sections) is described: the developer and the acetic acid used for processing autoradiographs extract selectively uranium acetate from DNA containing-structures which, after staining with lead citrate, leads to a characteristically 'bleached' appearance of the DNA.

Aldehydes↗
PubMed1973

Virus replication, cytopathology, and lysosomal enzyme response of mitotic and interphase Hep-2 cells infected with poliovirus.

Mitotic Hep-2 cells, selected by the PEL (colloidal silica) density gradient method and held in mitosis with Colcemid, are readily infected by poliovirus type I (Mahoney). They produce and release the same amount of virus as interphase, random-growing cells. In contrast to interphase cells, mitotic cells show no detectable virus-induced cytopathic effect at the light microscopy level and only slight alterations, consisting of small clusters of vacuoles, at the electron microscopy level. Mitotic cells contain the same total amount of lysosomal enzymes per cell as interphase cells, but they display no redistribution of lysosomal enzymes during the virus infection as interphase cells do. This supports the view that lysosomal enzyme redistribution is associated with the cytopathic effect in poliovirus infection but shows that virus synthesis and release is not dependent on either the cytopathic effect or lysosomal enzyme release. The possible reasons for the lack of cytopathic effect in mitotic cells are discussed.

Carcinoma↗