Oral candidiasis as a marker for esophageal candidiasis in the acquired immunodeficiency syndrome.
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Acquired Immunodeficiency Syndrome↗
Biomedical subjects
A Tavitian
Publications and source records attributed to A Tavitian.
N-ras gene activation in the RD human rhabdomyosarcoma cell line.
A transforming N-ras allele was molecularly cloned from the RD human rhabdomyosarcoma cell line, and the nature of its activation studied. Construction of chimeric recombinants between the RD-transforming allele and a normal human allele enabled us to localize the alteration responsible for the activation to the second exon of the N-ras gene. The nucleotide sequence of this exon, when compared to that of the normal allele, revealed a single difference at the 61st amino acid position of the encoded protein; the CAA codon for glutamine in the normal allele was mutated to a CAT codon for histidine in the RD-transforming allele. This result is the first description of a histidine replacing glutamine in the 61st position and provides further evidence that the 61st amino acid is one of the preferential sites for N-ras activation.
Alleles↗
Study of the 78A1 isolate of Moloney murine sarcoma virus. I. Molecular cloning and characterization.
The 78A1 isolate of Moloney murine sarcoma virus (78A1 Mo-MuSV) was cloned from a genomic library obtained from virus producer rat cells, in the lambda vector L47. Among the recombinants hybridizing with a probe specific for the v-mos sequences, we recovered a recombinant which contained leukaemia virus (MuLV) sequences and was able to transform both mouse and rat cells in transfection experiments. The cloned provirus could be rescued by both Mo-MuLV ecotropic and amphotropic viruses in mouse cells, but only with the amphotropic helper virus in rat cells. Comparative restriction mapping indicates that the 78A1 provirus is 200 bp longer than the HT1 provirus. The difference lies in the gag-pol junction region of Mo-MuSV. Other minor differences were found in the gag region, whereas the restriction patterns of the 3' parts of the proviruses were identical.
Animals↗
Study of the 78A1 isolate of Moloney murine sarcoma virus. II. Haematopoietic tropism and tumourigenicity.
A new isolate of Moloney murine sarcoma virus (Mo-MuSV), designated 78A1, has been molecularly cloned. The cloned genome, found to be larger than that of other known isolates of the same virus is close in size to that of the myeloproliferative sarcoma virus (MPSV), also a derivative of the original Mo-MuSV/Moloney murine leukaemia virus (Mo-MuLV) complex. Until now, MPSV was the only Mo-MuSV isolate known to be capable of inducing a myeloproliferative disease associated with a tumoural syndrome when injected intravenously into sensitive mice. We compared the biological activity of our cloned virus isolate (78A1) and that of another cloned Mo-MuSV virus (HT1) whose genome is slightly smaller than that of 78A1. The helper virus (Mo-MuLV) associated with the Mo-MuSV isolates was also injected alone as control. After injection into sensitive mice only the isolate 78A1, as well as MPSV caused a tumoural syndrome invading spleen, liver and other haematopoietic organs, and the appearance of granulo-macrophage precursors not requiring exogenous stimulating factors for their proliferation and differentiation. The 78A1 virus has a longer latency period (3 months) than MPSV (several days) and does not induce a typical myeloproliferative disease.
Animals↗
Integration of spleen focus-forming virus proviruses in Friend tumor cells.
Using the Southern blot procedure, we studied the presumed spleen focus-forming virus (SFFV) provirus integration sites in the genome of the premalignant and the malignant cells isolated during the course of Friend erythroleukemia. Two restriction endonucleases, PstI and BamHI, discriminated the presumed integrated SFFV proviruses from the endogenous xenotropic-mink cell focus-forming viral sequences. No SFFV integration sites were detectable in the premalignant cells, suggesting a random integration of SFFV proviruses in the genome of these cells. In contrast, SFFV proviruses were detected at a single or very few sites in the genome of all malignant cells we analyzed. These results indicate that the event leading to the malignant transformation in acute Friend leukemia is clonal. In two of the six animals examined, tumors cells isolated from the spleens and the livers of individual mice showed identical SFFV integration patterns. This last result suggests that in some cases different tumors in a same leukemic animal could be derived from a unique clonal event.
Animals↗
Granulomatous involvement of the liver in patients with AIDS.
During a one month period liver biopsy was carried out on eight patients with established acquired immune deficiency syndrome (AIDS) and two suspected of having AIDS to evaluate raised liver enzymes or unexplained fever and weight loss. Each of the 10 patients were found to have hepatic granulomas. Appropriate staining techniques showed acid-fast bacilli in seven of the liver specimens. One specimen contained numerous Cryptococcal organisms. Two biopsies showed granulomas but no organisms. Liver biopsy was found to be a high yield and rapid diagnostic procedure in patients with AIDS. Our results suggest that hepatic mycobacterial infection may be more common in the syndrome than previously recognised and that liver biopsy specimens should be examined routinely for the presence of acid-fast bacilli.
Acquired Immunodeficiency Syndrome↗
[Construction of an infectious retroviral vector for the expression of eucaryotic genes].
We describe here an infectious eucaryotic expression vector derived from Moloney Murine Leukemia (Mo-MuLV) provirus and recombined in plasmid pBR 322, for the expression of eucaryotic genes. Upstream of the cloning sites lie the 5' LTR and 700 bp of the gag sequences containing the splicing and encapsidation signals. Downstream of the cloning sites are situated the env gene and the 3' LTR containing the polyadenylation signal. So as to test the potential use of this vector, Herpes Simplex TK gene and E. Coli NeoR genes were cloned in the same transcriptional polarity as the viral LTRs. When DNA from the recombinant plasmid was transfected into mouse, rat, or human cell cultures, high yields of TK+ or NeoR colonies were obtained. Recombinant plasmids constructed with TK or NeoR genes in the opposite polarity failed to produce drug resistant colonies. Cotransfection with DNA of the Mo-MuLV competent helper provirus led to the rescue of chimeric virus capable of transmitting drug resistance.
Animals↗
Expression of c-ras and c-myc oncogenes in murine erythroleukemias induced by Friend viruses.
We have examined the expression of three cellular oncogenes (c-Ki-ras, c-Ha-ras and c-myc) in different stages of murine erythroleukemias induced in ICFW mice by Friend viruses (F-MuLV and SFFV) in comparison to normal mice spleens and bone marrows, including erythropoietically-stimulated spleens from phenylhydrazine-treated mice. There is no evidence of c-Ki-ras RNA expression in any of the tissues tested. c-Ha-ras RNA was found at similar levels in erythroleukemic cells and normal erythroid cells. In contrast, increased levels of normal 2.3 Kb and short 1.8 Kb c-myc RNA transcripts were detected in both early preleukemic and late leukemic phases of the diseases, as compared to normal erythroid cells. Apparently, neither myc gene amplification nor myc gene rearrangement was observed in erythroleukemias. Our results suggest a possible involvement of c-myc gene either in erythroid cell differentiation or in an early proliferation step of the erythroleukemic process.
Animals↗
Characterization of viral RNA in cells transformed by various isolates of Moloney murine sarcoma virus.
Intracellular polyadenylated viral RNA from cells infected by five different isolates of Moloney murine sarcoma virus (Mo-MuSV) was analysed by gel transfer hybridization. Genomic sizes of 4.6 kilobases (kb) for the ml-MuSV isolate, 5.2 kb for the m3- and 124-MuSV, 6.1 kb for the HTl-MuSV and 6.7 kb for the 78-Al-MuSV were determined. With the exception of the ml strain, subgenomic RNA species were found in cells infected by the various isolates. However, no common subgenomic RNA containing v-mos sequences could be characterized. Each transformed cell line expressed a different set of viral RNA species in terms of size and structure.
Animals↗
[Characterization of a subgenomic viral RNA in the polysomes of cells infected with the Moloney murine sarcoma virus].
We have detected a 1.6 kb RNA species in the polysomes of cells infected with the m1 strain of Moloney Murine Sarcoma Virus. This RNA contains the cellular transforming sequences (mos) as well as sequences located at both ends of the viral genome and is devoid of other internal viral sequences. This RNA appears to be spliced and might function as the messenger for the transforming protein of the Moloney Murine Sarcoma Virus.
Animals↗
[Effect of a selective inhibitor of ribosomal RNA on induction of differentiation of the Friend cell].
The selective inhibitor of ribosomal RNA synthesis toyocamycin, abolishes at very low concentrations, the erythroid differentiation of Friend cells when used under conditions where other inhibitors of DNA and RNA synthesis do not impede differentiation. Toyocamycin does not inhibit the synthesis of 16 S premessager RNA for globin, nor does it prevent splicing for mature 9 S globin messenger. Inhibition of differentiation might be explained by an effect at the translation level.
Animals↗
Effect of toyocamycin on oncornaviral production by acutely infected cells.
The adenosine analogue toyocamycin incorporates into the RNA species of mammalia cells and abolishes at low concentrations of the processing of 45S preribosomal nucleolar RNA into the mature 28 and 18S cytoplasmic ribosomal RNAs. We have previously shown that toyocamycin depresses the production of the Friend leukemia viral complex by chronically infected cells. In this article, we report the study of the action of the drug on viral RNA in acutely infected cells. We found that, although abolishing viral production, the incorporation of toyocamycin does not inhibit the formation of mature viral messenger RNAs nor prevent the synthesis of specific viral proteins. These results are obtained at concentrations of analogue sufficient to abolish the appearance of mature cytoplasmic ribosomal RNA.
Animals↗
Characterization of a large genomic size Moloney murine sarcoma virus produced by a transformed rat cell line.
A rat cell line (78A1) transformed by the Moloney murine sarcoma virus-Moloney murine leukaemia virus (Mo-MuSV-MuLV) complex was found to produce a sarcoma virus different from the isolates previously described. Analysis of intracellular RNA of the 78A1 cell line by electrophoresis on agarose gel, and hybridization with DNA probes specific to M1-Mo-MuSV and v-mosMo sequences revealed a size of 6.7 kilobases (kb) for the RNA of this sarcoma virus. This genome is larger than those of m1, m3, HT1 and 124 isolates and slightly smaller than the myeloproliferative sarcoma virus genome (7.0 kb).
Animals↗
Comparative immunochemical study of ribosomal proteins from various mammalian cells by two-dimensional immunoelectrophoresis.
Proteins isolated from ribosomal subunits of various mammalian cels were analysed comparatively by two different methods: a two-dimensional polyacrylamide gel electrophoresis system and a recently described two-dimensional immunoelectrophoresis technique. For this purpose, antisera were raised in rabbits against the total mixture of ribosomal proteins from murine cells. These sera were characterized by ring-test, double immunodiffusion and two-dimensional immunoelectrophoresis. They were shown to contain antibodies to a large number of ribosomal proteins. Immunoelectrophoretic analysis of 60S and 40S subunit proteins from rabbit, lamb, canine and human cells using anti-murine sera revealed a striking conservation of their antigenic properties. These results corroborated those obtained by two-dimensional polyacrylamide gel electrophoresis.
Animals↗
[A virus produced by human embryonic cells infected with Moloney murine sarcoma virus].
Human embryonic cell cultures, infected with the Mouse sarcoma virus, complex (Moloney isolate), produced a virus that specifically transformed mink lung cells. The non-transforming helper virus could infect Mouse cells as well as a wide range of other mammalian cells. These observations could suggest the presence of either several viruses in the virus stock and/or stable recombinants.
Animals↗
Kinetic studies on ribosomal proteins assembly in preribosomal particles and ribosomal subunits of mammalian cells.
Proteins were isolated from 80-S preribosomal particles and ribosomal subunits of murine L5178Y cells after short and longer periods of incubation with tritiated amino acids. The labeling patterns of ribosomal proteins were compared by two-dimensional polyacrylamide gel electrophoresis. The analysis of isotopic ratios in individual protein spots showed marked differences in the relative kinetics of protein appearance within nucleolar peribosomes and cytoplasmic subunits. Among the about 60 distinct proteins characterized in 80-S preribosomes, 9 ribosomal proteins appeared to incorporate radioactive amino acids more rapidly. These proteins become labeled gradually in the cytoplasmic ribosomal subunits. It was found that one non-ribosomal protein associated with 80-S preribosomes takes up label far more quickly than other preribosomal polypeptides. It is suggested that this set of proteins could associate early with newly transcribed pre-rRNA, more rapidly than others after their synthesis on polyribosomes, and could therefore play a role in the regulation of ribosome synthesis. In isolated 60-S and 40-S ribosomal subunits, we detected five proteins from the large subunit and four proteins from the small subunit which incorporate tritiated amino acids more quickly than the remainder. These proteins were shown to be absent or very faintly labeled in 80-S preribosomal particles, and would associate with ribosomal particles at later stages of the maturation process.
Animals↗
Ribosomal proteins synthesis and exchange in the absence of 28-S and 18-S ribosomal RNA synthesis in L5178Y cells.
The effect of the adenosine analogue toyocamycin on ribosomal proteins synthesis and assembly within ribosomal particles was investigated in the murine cells, L5178Y. The analogue was used for periods not exceeding 5 h, at a concentration which permits the synthesis of ribosomal precursor RNA but inhibits the maturation process. The following observations were made: 1. Ribosomal proteins, synthesized de novo in the presence of the drug, were associated with toyocamycin-containing 45-S pre-rRNA in preribosomal-like 80-S ribonucleoproteins which accumulated in the nucleolus. Two-dimensional electrophoresis revealed a full protein complement of these particles, although minor discrepancies were observed in the relative proportions of a limited number of polypeptides. 2. In the absence of 28-S and 18-S rRNA formation, a surprisingly high proportion of newly synthesized ribosomal proteins were incorporated into high-salt washed ribosomal subunits. The extent of individual protein exchange as well as their apparent turnover rates were markedly heterogeneous. Most of these exchangeable proteins were shown to be labeled rapidly in ribosomal subunits of normal cells. Some alternative interpretations of these results are discussed.
Animals↗
Studies on the distribution of ribosomal proteins in mammalian ribosomal subunits.
Murine L5178Y cell ribosomes were dissociated into subunits either with potassium chloride in the presence of puromycin or with the chelating agent EDTA. The proteins of ribosomal subunits obtained by these different methods were compared by means of bidimensional polyacrylamide gel electrophoresis. KCl-derived 60S and 40S subunits were shown to contain 38 and 31 proteins respectively, 3 of them having identical electrophoretic mobilities. Preparations of EDTA-dissociated ribosomal subparticles contained different proportions of these proteins, and 11 major spots were shared between the EDTA-derived large and small ribosomal subunits. Furthermore, 10 proteins absent from subunits treated by high concentrations of KCl were reproducibly found in EDTA-treated ribosomal subparticles.
Animals↗