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Biomedical subjects

J Peries

Publications and source records attributed to J Peries.

At least 55 records · Page 3Linked to original sources
PubMed1983

Characterization of RNase H activity associated with reverse transcriptase in simian foamy virus type 1.

Spumavirinae or foamy viruses have been shown to have a characteristic RNA-dependent DNA polymerase activity. We demonstrate here the existence of an RNase H activity that copurifies with the 81-kilodalton monomeric polypeptide, which carries the RNA-dependent DNA polymerase activity of simian foamy virus type 1. RNase H degrades RNA hybrid substrates; however, it does not solubilize single-stranded RNAs. Inactivation assays with heat, high levels of bivalent cations, ethidium bromide, and sodium fluoride suggest that the RNase H catalytic site could be topologically independent from the DNA polymerase catalytic site.

Animals↗
PubMed1983

The diffuse neuroendocrine (APUD) system.

The bulk of experimental evidence indicates that the APUD series of cells is a distinct system based upon common pathophysiological features. The diffuse nature of this system with elements in the central and peripheral nervous system suggests a more complex interaction of the body's homeostasis than has been established. It is probable that as radioimmunological and radioenzymatic assays become more widely available and standardized, other apudomas will be described. Finally, an understanding of the APUD concept, with its peculiar pluripotential for the production of biogenic amines and peptides, the multicentric nature of the disease and the possibility of multiple cell involvement, is of key importance in managing patients. Studies of the apudomas will also advance the understanding of the normal physiologic interrelationships of the APUD cells.

APUD Cells↗
PubMed1982

Murine retrovirus genome directs the synthesis of gag protein precursor early after infection.

Incoming type C retroviral genomic 35S RNA is present in polysomes of undifferentiated and differentiated murine teratocarcinoma cell lines at 4 hours after infection. At the same time a 65,000 daltons viral specific protein is produced by the infected cells. These data present evidence that incoming viral RNA serves as messenger for the synthesis of gag protein precursor Pr65 early in the infectious cycle of ecotropic murine retrovirus.

Animals↗
PubMed1982

Bovine enteric coronavirus structure as studied by a freeze-drying technique.

A strain of bovine coronavirus (F15) was studied by electron microscopy using a freeze-drying technique. Purified coronavirus preparations show three different categories of image: (i) 'blackberry-like' virions, (ii) virions with a smooth depression at their surface, and (iii) apparently broken particles showing very clearly the areas of spike insertion in the virus membrane. Virus projections resemble 'mushrooms' with the 'stalk' inserted at the virus membrane. A model of the virion structure is proposed.

Animals↗
PubMed1982

Reverse transcriptase from simian foamy virus serotype 1: purification and characterization.

Chromatography on heparin-Sepharose, known for its affinity for nucleotide-binding polypeptides, was used to purify the viral RNA-dependent DNA polymerase (reverse transcriptase) from the core polypeptides of simian foamy virus type 1. This procedure allowed the recovery of highly purified enzyme with a high specific activity. The average molecular weight of this monomeric enzyme is 81,000 and is thus comparable to that found for other known primate retroviruses. Reverse transcriptase activity of simian foamy virus type 1 requires a ribonucleotide template as a primer or otherwise a DNA with 3'-OH ends. Other optimal conditions of activity are reviewed. Heat inactivation studies led to the concept of an enzyme with two loci, one specific for the substrate and the other for the template-primer.

Hot Temperature↗
PubMed1981

[Absence of the chemical activation of type C endogenous viruses in cells of 129/J mice].

Production of Type C virus by Mouse cells generally activated by chemical agents does not occur in 129/J Mouse cells. No viral production, as tested by reverse transcriptase activity and electron microscopic methods can be detected in cells treated by chemical inducers. Immunofluorescence does not reveal the presence of viral specific proteins and viral RNA expression determined by molecular hybridization between cellular RNA and viral cDNA does not increase as it does in BALB/c cells under the action of the inducers studied.

Animals↗
PubMed1981

Biochemical characterization of simian foamy virus type i.

Simian syncitium-forming ("foamy") virus type I (SFV1) was characterized biochemically. RNA was extracted from purified virus either with 0.1 per cent SDS or by the standard phenol-chloroform method. By both techniques a main component of 65-70S was found. Denaturation of the 65-70S RNA by heat resulted in a shift of the sedimentation coefficient mainly to a 30-35S component. Electrophoresis on a composite polyacrylamide gel demonstrated the existence of three minor RNA's: 8S, 5S and 4S respectively. PAGE-SDS analysis of disrupted purified virions enabled the separate migration of five viral proteins and the identification of two main proteins: a 30 kd polypeptide and a 70 kd polypeptide.

Animals↗
PubMed1981

Studies on the restriction of ecotropic murine retrovirus replication in mouse teratocarcinoma cells.

Retrovirus infection of cultured murine teratocarcinoma cells depends upon the state of differentiation. We have used two cell lines derived from a teratocarcinoma of mouse, strain 129. One, an undifferentiated pluripotential cell line (PCC4), is restrictive to viral infection, while the other, a differentiated myoblast-derived cell line (PCD1), is fully permissive to virus replication. We have shown that no virus RNA expression can be found in PCC4 cells 48 h post-infection and that no nucleic acid sequences can be found in an integrated form in PCC4 cells. However, the kinetics of formation of free proviral intermediates show that the three forms (I, II and III) of free virus DNA are synthesized in both PCC4 and PCD1. Free proviral DNA disappears gradually after 24 h in PCC4 cells while all forms increase in PCD1. These results suggest that the viral multiplication restriction occurs somewhere between the proviral DNA synthesis and integration of DNA in the cellular genome.

Animals↗
PubMed1981

Study of a human heteroploid cell line cryptically infected by a murine oncornavirus.

This report concerns the establishment of a human cell line cryptically infected by a murine leukemia virus (MuLV). This cell line, named J112, is characterized by the presence of genetic viral information in a majority of cells as demonstrated by immunological and virological methods, and by the absence of detectable viral activity in the supernatant culture fluids. Nevertheless, electron microscopy demonstrated the presence of a small number of particles which have the morphology of immature type C particles. We discuss the importance of this experimental model in relationship with non-producing (NP) infections of human cells by oncogenic retroviruses.

Cell Line↗
PubMed1980

[Presence of enteric viruses in non-diarrheic canine stools].

Rota-, corona- and parvovirus particles have been visualized by direct electron microscopy in canine stools collected at random in Paris streets. A possible involvement of these viruses in gastroenteric diseases is discussed in the light of these findings.

Animals↗
PubMed1980

Electron microscopy detection and characterization of viral particles in dog stools.

A number of apparently normal dog stool samples, randomly collected on the sidewalks of Paris were examined by Electron Microscopy. The study revealed the presence of viral particles in 27 cases. Morphological criteria lead to the characterization of rotavirus in 2 specimen, coronavirus in 7 and parvovirus in 5. Rotavirus particles appeared always alone while coronavirus and parvovirus particles were present together in 5 cases. Similar particles have been implicated in animal and human gastroenteritis. The importance of their presence in canine dejections is discussed in view of pollution by dog stools of urban and suburban areas.

Animals↗
PubMed1980

Biochemical characterization of endogenous type C virus information in differentiated and undifferentiated murine teratocarcinoma-derived cell lines.

Undifferentiated teratocarcinoma cells express sixfold-higher levels of endogenous xenotropic type C virus-related RNA than differentiated cells. Three species of polyadenylated viral RNA (35S, 24S, and 14S) have been identified in the undifferentiated teratocarcinoma cells. Paradoxically, neither viral particles nor viral proteins have been detected in these cells.

Animals↗
PubMed1978

[Characterization of the viral-type nucleotide sequences detected in the RNA of human leukaemic cells by probes of murine and simian origins (author's transl)].

Molecular hybridization techniques were used for searching nucleic acid sequences homologous to murine and simian oncornaviral genomes in the RNA of various categories of human leukaemic cells. We report attempts to characterize the sequences that were detected in defined categories of leukemias. It is shown that: i) although there is some correlation between the two probes used in our study with regard to the positivity or the negativity of the tests for the same leukaemic cases, there are also some discrepancies since some of the cases are positive with one probe and negative with the other; ii) the common sequences of the two probes when isolated, were ineffective to detect any complementary sequences in leukemic cases which were scored as positive when the entire probes were used; iii) the complementary sequences detected in three positive cases of acute myelogenous leukemias by a recycled probe are additive and therefore most probably distributed along the viral genome.

Animals↗
PubMed1977

Replication of Mouse Sarcoma Virus (Moloney) and its helper in a human heteroploid cell line of malignant origin.

A human heteroploid cell line of malignant origin (J111) was infected with Mouse Moloney Sarcoma Virus. [MSV-M(MLV)]. The replication of the virus was demonstrated by different methods. After a few passages of infected cultures, the transforming component of MSV-M(MLV) disappeared from the supernatant fluids and cells. The non transforming helper component continued to be produced. The relatively low amount of helper virus released by the cells suggests a control of its replication in the J111 cellular system.

Aneuploidy↗
PubMed1975

Search for nucleic acid sequences complementary to a murine oncornaviral genome in poly(A)-rich RNA of human leukemic cells.

The presence of viral-like sequences in the RNA of various types of leukemic cells was investigated by hybridizing cellular poly(A)-containing RNA with cDNA synthesized in an endogenous system of purified Moloney murine sarcoma virus [M-MSV-(MLV)]. Poly(A)-RNA-cDNA hybrids were detected by assaying their resistance to S1 nuclease. Hybrids were found in 22 out of the 46 leukemias that were tested. None of the controls, including material obtained from buffy coats, bone marrow cells, and a continuous human cell line, was positive. Positive cases were found in all the different categories of leukemias with the exception of chronic myelogenous leukemias. There was no definite corelation between the category of leukemia and positivity. A few cases contained a very high proportion of poly(A)-RNA-cDNA hybrid.

Base Sequence↗