Search PubMed⌕ Search

Biomedical subjects

R I Carp

Publications and source records attributed to R I Carp.

137 records · Page 8Linked to original sources
PubMed1967

Thymidine kinase from normal, simian virus 40-transformed and simian virus 40-lytically infected cells.

Simian virus 40 (SV40) infection of human diploid cells failed to cause an enhanced production of thymidine kinase during the first 10 days after infection. Thymidine kinase activities from extracts of SV40-transformed cultures (human or simian) were considerably higher than the activity levels in extracts from the normal cells of origin. In addition, whereas the kinase activities obtained for human diploid cultures decreased as the cell sheet became confluent, the kinase activities for SV40-transformed human cells remained high after confluence was reached. Antisera obtained from hamsters bearing SV40 or adeno-7-SV40 hybrid virus tumors selectively inhibited enzyme from transformed sources (human or simian). Also, the antisera selectively inhibited enzyme extracted from SV40-lytically infected monkey cells. Sera from normal animals or from hamsters bearing polyoma tumors failed to inhibit enzymes from normal, SV40-transformed, or SV40-lytically infected cells. The Michaelis constant of partially purified enzyme from SV40-transformed cells was two to five times as high as that obtained for partially purified enzyme from human diploid cell cultures.

Adenoviridae↗
PubMed1966

Effects of cycloheximide and puromycin on synthesis of simian virus 40 T antigen in green monkey kidney cells.

Gilden, R. V. (Wistar Institute, Philadelphia, Pa.), and R. I. Carp. Effects of cycloheximide and puromycin on synthesis of simian virus 40 T antigen in green monkey kidney cells. J. Bacteriol. 91:1295-1297. 1966.-Synthesis of the simian virus 40 (SV40) T antigen in primary African green monkey kidney cells was abolished when cycloheximide was added up to 10 hr postinfection. In contrast, puromycin, another inhibitor of protein synthesis, did not suppress antigen production. The basis of this differential effect was the inability of puromycin to inhibit protein synthesis in the cells used. This was shown by the failure of the drug to depress the incorporation of labeled amino acid into protein and also failure to inhibit poliovirus synthesis. The puromycin preparation used was very effective in inhibiting poliovirus synthesis in HeLa cells. Thus, appearance of the SV40 T antigen is dependent on protein synthesis in infected cells.

Animals↗
PubMedDate not supplied

Extensive degeneration of catecholaminergic neurons to scrapie agent 87V in the brains of IM mice.

Scrapie is a degenerative disease of the central nervous system of sheep and goats. The causative agent has been passaged to a number of laboratory species, including mice and hamster. Amyloid plaque formation and vacuolation, the signs of senile dementia, are found in the brains of mice infected with 87V scrapie agent. Dopamine (DA) and norepinephrine (NE) concentrations in the brains of scrapie-infected mice were measured with high-performance liquid chromatography-electrochemical detector (HPLC-ECD). A significant decrease in NE level was exhibited in all regions tested, whereas the level of DA decreased significantly only in cerebral cortex. Immunohistochemistry was used to examine immunoreactive catecholamine neurons in substantia nigra and locus ceruleus using antisera against tyrosine hydroxylase (TH). The population of TH-immunoreactive neurons in the substantia nigra and locus ceruleus were significantly decreased in scrapie-infected mice compared to controls. These data suggest that both the noradrenergic and dopaminergic system are sensitive to the action of scrapie agent 87V and that changes in the catecholamine levels in the brains of scrapie-infected mice may contribute to some of the clinical symptoms of the diseases, such as ataxia and apraxia.

Animals↗
PubMedDate not supplied

Titers of murine leukemia virus are higher in brains of SAMP8 than SAMR1 mice.

To elucidate possible causes of premature aging seen in a strain of senescence-accelerated prone (SAMP8) mice, levels of murine leukemia virus (MuLV) were quantitated in various tissues of SAMP8 by an SC-1/UV plaque assay. MuLV levels in SAMP8 tissues were compared to those seen in the closely related SAMR1 strain, which is resistant to premature aging. MuLV titers were found to be higher in blood and spleen and much higher in brain of SAMP8 than in the same tissues of SAMR1. MuLV levels were seen to increase in SAMP8 brain with increasing age. Virus typing experiments indicated that the MuLV from SAMP8 brain is N-tropic, as is the MuLV seen in the AKR strain, one of the SAM progenitor strains. MuLV from SAMP8 brain was able to grow well in SAMR1 mouse embryo cells, indicating that it may be possible to infect SAMR1 mice with the SAMP8 MuLV to determine the effects of the virus on aging of SAMR1 mice.

Aging↗
PubMedDate not supplied

The nature of the unconventional slow infection agents remains a puzzle.

Unconventional slow infections are progressive transmissible degenerative disorders of the central nervous system. The human diseases belonging to this group are Creutzfeld-Jakob disease, kuru, and Gerstmann-Straussler syndrome. Scrapie, transmissible mink encephalopathy, chronic wasting disease of mule deer and elk, and the recently discovered bovine spongiform encephalopathy are similar diseases found in animals. Unusual characteristics of the unconventional slow infections clearly distinguish these disorders from conventional infections. These include: unusually long incubation periods (from months to years); progressive CNS degeneration with characteristic histopathological lesions; the lack of an immune or inflammatory response; unconventional biological and physical properties of the etiologic agents. There has been considerable controversy concerning the nature of the causative agent. The 3 main hypotheses, virus, virino, and modified host protein, are reviewed relative to their ability to explain the properties of the agent and the unusual characteristics of the disease process. The discovery of an abnormal structure, termed scrapie associated fibrils (SAF) and an abnormally modified 33-37 kDa host-encoded glycoprotein unique to unconventional slow infections opened new areas of intense interest and investigation. SAF are abnormal filamentous structures which copurify with infectivity and possess characteristics of "amyloids." The major component of SAF is the host-encoded scrapie-specific protease resistant glyco-protein. Considerable data has accumulated on the biochemistry, immunology and molecular biology of this host coded scrapie protein. The relationship of SAF and the scrapie-specific protein to the infectious agent is discussed in the context of each of the "nature of the agent" hypotheses.

Animals↗
PubMedDate not supplied

Increased expression of prion protein is associated with changes in dopamine metabolism and MAO activity in PC12 cells.

Prion diseases of humans and animals occur following infection with infectious agents containing PrP(Sc) or in situations in which there is a mutation of the prion protein (PrP) gene. The cellular prion protein (PrP(C)) is a sialoglycoprotein that is expressed predominantly in neurons. PrP(C) is converted into a pathogenic form of PrP (PrP(Sc)), which is distinguishable from PrP(C) by its relative resistance to protease digestion. A number of postulates have been advanced for the function of normal PrP (PrP(C)), but this issue has not been resolved. To investigate the function(s) of PrP(C), we established clonal PC12 cell lines, which have elevated PrP(C) expression. The results show that there were alterations in dopamine metabolism and in monoamine oxidase (MAO) activity in transfected PC12 cells that overexpress PrP(C). There was an increase in concentration of DOPAC, a metabolite of dopamine, and in MAO activity in cells overexpressing PrP(C). MAO is involved in oxidative degradation of dopamine (DA). Our data suggest that PrP(C) plays a role in DA metabolism by regulating MAO activity.

Animals↗
PubMedDate not supplied

Immunodiagnosis of prion disease.

The immunodiagnosis of prion diseases is of critical importance due to the transmissibility of these conditions and their fatal prognosis. A panel of monoclonal and polyclonal antibodies have been generated for use in the study and diagnosis of these diseases. This manuscript describes the generation and characterization of these antibodies as well as their diagnostic application.

Adult↗