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Biomedical subjects

S Rasheed

Publications and source records attributed to S Rasheed.

At least 91 records · Page 5Linked to original sources
PubMed1983

Characterization of a differentiated cat melanoma cell line.

We have established several long-term cultures of a naturally occurring metastatic melanoma of a domestic cat. The cells are fully differentiated as indicated by the Fontana-Masson staining of the melanin in the perinuclear region and by electron microscopy of the cytoplasmic melanosomes in various stages of development. The melanoma cells do not produce virus particles or the major core proteins (i.e., protein with a molecular weight of 30,000) of the feline leukemia virus or the endogenous cat virus RD-114. Retrovirus is also not induced when melanoma cultures are treated with 5-iodo-2'-deoxyuridine or bromodeoxyuridine and cocultivated with susceptible cells. Treatment of cells with N6,O2'-dibutyryl cyclic adenosine 3' :5'-monophosphate or theophyllin, however, accentuates melanin production and increases the number of pigmented cells. The cultured cells develop melanotic tumors in s.c. inoculated newborn cats and athymic nude mice. As far as we can ascertain, this is the first report of a spontaneous malignant melanoma of a cat which provides an important resource for studying cell differentiation in vitro.

Animals↗
PubMed1982

Characterization of a highly oncogenic murine leukemia virus from wild mice.

We have isolated a highly lymphomagenic wild mouse virus by passage of a weakly oncogenic amphotropic murine leukaemia virus (MuLV-A) in NIH Swiss mice. This virus is similar in host range, interference and neutralization properties to that of the inoculated amphotropic virus but is distinct from it biochemically and causes lymphomas in 90-100% of mice within 1-2 months. Our results indicate that this highly oncogenic virus is a recombinant of wild mouse MuLV-A and sequences related to env gene region of the endogenous xenotropic virus of NIH Swiss mice.

Animals↗
PubMed1982

Role of endogenous cat retrovirus in cell differentiation.

Several long-term cultures were established from a spontaneous melanoma of a cat. Cells were rounded or spindle shaped and exhibited black/brown pigmentation in the cytoplasm. No virus was released from these cells spontaneously or after treatment with chemicals. However, exogenous infection of the cat melanoma cells with the endogenous cat virus RD114 resulted in remarkable morphological and functional changes. Most of the RD114 virus-infected cells exhibited multiple neuritic extensions and about 1-2% of the population showed characteristics of neuronal cells. Because human, mouse, and hamster melanoma cultures infected with various mammalian retroviruses, including the RD114 virus, did not display any morphological alteration, it is concluded that the neuronal cell differentiation in the cat melanoma cells is a consequence of its specific interaction with the endogenous cat retrovirus.

Animals↗
PubMed1982

Characterization of genome structure of amphotropic and ecotropic wild mouse retroviruses.

We studied the RNA genomes of several wild mouse type C retroviruses by using RNase T1-oligonucleotide fingerprinting. The amphotropic and ecotropic viruses of field strain 1504 produced very similar oligonucleotide fingerprints, but each also had several unique oligonucleotides. All of these unique oligonucleotides were located in the env gene region and were probably responsible for the host range differences between these viruses, as well as the lymphomagenic and paralytogenic properties of the viruses. We obtained similar results with the amphotropic and ecotropic viruses of another field strain (4070), which was isolated from a mouse from a different trapping area. The amphotropic viruses of several field strains (strains 1504, 4070, and 1313) were more closely related than the ecotropic viruses of different strains (strains 1504, 4070, and 4996). These findings suggested that the genetic sequences of the amphotropic viruses are more conserved than those of ecotropic viruses isolated from the same wild mice.

Animals↗
PubMed1982

Molecular cloning, genomic analysis, and biological properties of rat leukemia virus and the onc sequences of Rasheed rat sarcoma virus.

Rasheed rat sarcoma virus (RaSV) has been shown to code for a protein of 29,000 Mr not present in replication-competent rat type C helper virus (RaLV)-infected cells. This protein is a fused gene product consisting of a portion of the RaLV p15 gag protein and the transformation-specific 21,000 Mr (p21) ras protein, which is also found in Harvey murine sarcoma virus. We now report the molecular cloning of both the SD-1 (Sprague-Dawley) strain of RaLV and the transforming ras sequences of RaSV. Heteroduplex analysis of these cloned DNAs demonstrated that the RaSV ras gene (v-Ra-ras) was inserted into the rat type C viral genome with a small deletion of RaLV genetic information in the 5' region of the gag gene and that the v-Ra-ras gene (0.72 kilobase pair) is homologous to and colinear with the p21 ras gene of Harvey murine sarcoma virus (v-Ha-ras). Restriction enzyme mapping confirmed the homology demonstrated by heteroduplex mapping, showing strong site conservation of restriction endonucleases known to cleave v-Ha-ras. Cloned v-Ra-ras DNA transformed NIH 3T3 cells, inducing the synthesis of the p29 RaSVgag-ras protein.

Base Sequence↗
PubMed1981

Natural killer cell activity in a population of leukemia-prone wild mice (Mus musculus).

Natural cell-mediated cytotoxicity against YAC-I targets was measured in splenocytes from leukemia-prone wild mice trapped near Lake Casitas (LC) in southern California. Cytotoxicity was mediated by cells that were non-adherent to nylon wool, non-phagocytic and resistant to thy-1.2 antiserum plus complement. Natural MuLV viremia in LC mice did not impair splenic cytotoxicity against TAC-I target cells, Cells infected with amphotropic and ecotropic MuLV of wild mouse origin were not appreciably lysed by LC splenic effectors. Although variable levels of cytotoxicity were detected against TAC-1 by normal spleen cells, consistently low levels of cytotoxicity against allogenic LC lymphoma, sarcoma and carcinoma targets were found using the same splenocytes. These results indicate that LC mice possess splenocytes with the characteristics of natural killer (NK) cells as defined in inbred mice. The resistance of LC-derived targets to lysis by LC NK cells suggests that NK cells may not be involved in natural tumor immunosurveillance or that the development of spontaneous tumors may involve escape from NK-mediated effector mechanisms.

Animals↗
PubMed1981

Identification and cloning of endogenous retroviral sequences present in human DNA.

Using nonstringent annealing conditions and a 2.75-kilobase segment of cloned African green monkey DNA that specifically hybridizes to the proviruses of AKR ecotropic murine leukemia virus (MuLV) and baboon endogenous virus (BaEV) as a probe, we detected related sequences in three different preparations of human brain DNA fragments. The blot-hybridization pattern obtained with cleaved human DNA was similar to that previously reported for the interaction of MuLV cDNA and cleaved mouse DNA and suggested the presence of numerous copies of retrovirus-related sequences in the human genome. The labeled 2.75-kilobase fragment derived from cloned monkey DNA was used to screen a human DNA library in Charon 4A. One clone obtained hybridized to three contiguous MuLV-and BaEV-reactive fragments of the cloned monkey DNA and to multiple fragments of human DNA including a prominent 1.0-kilobase EcoRI fragment also present in the clone.

Animals↗
PubMed1981

Rat sarcoma virus: further analysis of individual viral isolates and the gene product.

Rasheed rat sarcoma virus, derived by in vitro cocultivation of two rat cell lines (Rasheed et al., Proc. Natl. Acad. Sci. U.S.A. 75:2972-2976, 1978), has been reported to code for a protein of 29,000 Mr, immunologically related to the 21,000 Mr src gene product of Harvey and Kirsten sarcoma viruses. Rat sarcoma virus p29 was thought to contain at least part of a rat type C virus structural protein, since antiserum prepared against whole rat virus was able to immunoprecipitate rat sarcoma virus p29 but not Harvey or Kirsten sarcoma virus p21 (Young et al., Proc. Natl. Acad. Sci. U.S.A. 76:3523-3527, 1979). We now report that antiserum directed against rat type C virus p15, but not viral p12, p10, or p27, immunoprecipitated rat sarcoma virus p29. The p15 antiserum was also able to immunoprecipitate both denatured p29 and a peptide derived by V-8 protease cleavage of p29, indicating that this antiserum contains antibodies directed against primary amino acid determinants. Finally, five separate isolates of rat sarcoma virus were found to code for p29, which indicates that a highly specific site of recombination is involved in the generation of sarcoma viruses in rat cells.

Animals↗
PubMed1981

Viral susceptibility of skin fibroblasts from patients with Huntington disease.

Cultured skin fibroblasts from patients with Huntington disease (HD) and age-matched controls were tested for susceptibility to vesicular stomatitis virus (VSV) and transformation by Kirsten mouse sarcoma virus (KiMSV). The HD and control cells could not be distinguished on the basis of viral replication, plaque morphology, virus yield, or susceptibility to transformation by KiMSV. These findings suggest that the HD gene product, if expressed within peripheral tissue, does not selectively alter or interfere with viral replication.

Cell Transformation, Viral↗
PubMed1981

Growth properties and susceptibility to viral transformation of skin fibroblasts from individuals at high genetic risk for colorectal cancer.

Growth characteristics and susceptibility to viral transformation were compared in cultured skin fibroblasts from patients with Gardner's syndrome (GS), those with familial polyposis coli (FP), asymptomatic family members, and unrelated controls. Compared to cells from unrelated controls, cells from 4 of 5 GS patients were transformed by Kirsten murine sarcoma virus at 100- to 1,000-fold increased efficiency. The transformation efficiencies of fibroblasts from 2 of 3 FP patients were 10- to 100-fold greater than those of unrelated controls. However, because the fibroblasts from some of the young asymptomatic GS and FP family members also transformed at higher efficiency than did cells from unrelated controls, long-term observation of these families is required. This would determine whether or not these members develop clinical manifestations of GS or FP and thus establish the specificitiy of this assay for detection of individuals bearing the mutant gene. Compared to fibroblasts from unrelated controls, GS and FP fibroblasts showed a twofold to threefold increased saturation density and plating efficiency, but this difference was not noted with fibroblasts from most of the asymptomatic family members.

Adolescent↗
PubMed1980

Akvr-1, a dominant murine leukemia virus restriction gene, is polymorphic in leukemia-prone wild mice.

We describe a restriction gene (Akvr-1, for AKR virus restriction) that is polymorphic for two alleles, Akvr-1R (restrictive) and Akvr-1r (susceptible), in a feral population of mice (Mus) musculus domesticus) at a squab farm near Lake Casitas (LC) in southern California. Akvr-1k is a dominant allele that exhibits 100% penetrance in prevention of viremia of AKR endogenous retrovirus and of virus-mediated lymphoma in LC (Akvr-1RR) X AKR F1 hybrids. The restriction phenotype segregates as a single Mendelian locus in backcrosses to AKR mice. Akvr-1R likewise is effective in restriction of NB-tropic Moloney murine leukemia virus-induced viremia and NB-tropic Friend virus-induced splenomegaly but fails to restrict expression or pathogenesis of LC-derived amphotropic retrovirus. Pleiotropic restriction of AKR, Friend, and Moloney ecotropic viruses, but not of amphotropic virus, suggests that the viral targets of Akvr-1 in the three ecotropic viruses are similar to each other and distinct from the target in the LC-amphotropic virus. The relationship of Akvr-1 to previously reported murine restriction loci Fv-1, Fv-2, and Fv-4 is discussed.

AKR murine leukemia virus↗
PubMed1980

Prevention of paralysis and suppression of lymphoma in wild mice by passive immunization to congenitally transmitted murine leukemia virus.

Lake Casitas wild mice were passively immunized as newborns with antiserum to congenitally transmitted murine leukemia virus. Immunization with immunoglobulin having a high neutralizing titer to ecotropic virus and a low titer to amphotropic virus correlated with the complete prevention of paralysis and a slight (25%), but statistically insignificant, reduction in the incidence of lymphoma. Occurrence of other tumor types and total mortality rate were not affected by immunization.

Animals↗