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A Talavera

Publications and source records attributed to A Talavera.

At least 55 records · Page 3Linked to original sources
PubMed1991

Isolation and molecular characterization of the swinepox virus thymidine kinase gene.

Swinepox virus (SPV), the only member of the Suipoxvirus genus, shows little antigenic relatedness or DNA homology to members of the other poxvirus genera. A SPV thymidine kinase (TK) gene was detected and mapped to the left end of the HindIII G fragment using degenerate oligonucleotide probes. Cloning and sequencing of a 1.8-kb HindIII-BamHI fragment containing the SPV TK gene revealed an open reading frame (ORF) of 181 amino acids yielding a predicted polypeptide of Mr 20.6 kDa with significant homology to both poxvirus and vertebrate thymidine kinases. Comparison with other TK protein sequences showed that the SPV thymidine kinase was closely related to the TK genes of avipoxviruses (52.0%) and vertebrates (57.1-59.7%). The TK gene from African swine fever virus (ASF) showed little homology (30.5%) to the SPV TK gene suggesting that these two viruses are not closely related though they share many biochemical features and infect a single, common mammalian host (swine). The SPV TK gene, like that of other poxviruses, is transcribed early, and when cloned into a TK- strain of vaccinia converted the virus to a TK+ phenotype. BUdRR mutants of SPV contained frameshift, deletion, and missense mutations in the TK ORF.

Amino Acid Sequence↗
PubMed1986

Hairpin loop structure of African swine fever virus DNA.

The ends of African swine fever virus genome are formed by a 37 nucleotide-long hairpin loop composed, almost entirely, of incompletely paired A and T residues. The loops at each DNA end were present in two equimolar forms that, when compared in opposite polarities, were inverted and complementary (flip-flop), as in the case of poxvirus DNA. The hairpin loops of African swine fever and vaccinia virus DNAs had no homology, but both DNAs had a 16 nucleotide-long sequence, close to the hairpin loops, with an homology of about 80%. An analysis of African swine fever virus replicating DNA showed head-to-head and tail-to-tail linked molecules that may be replicative intermediates.

African Swine Fever Virus↗
PubMed1986

Transcription and translation maps of African swine fever virus.

A transcription map of African swine fever (ASF) virus DNA was obtained by hybridization of 32P-labeled early and late RNAs synthesized in Vero cells infected with ASF virus to dot-blots containing cloned restriction fragments spanning the viral genome. Early RNAs synthesized in infected cells in the presence of protein or DNA synthesis inhibitors hybridized preferentially to four regions in the genome, with coordinates E1 (0-51.9 kbp), E3 (63.7-75.2 kbp), E5 (100.1-111.6 kbp), and E7 (150-170 kbp). Late RNA present in infected cells after DNA replication hybridized with essentially all the genome. The RNA synthesized in vitro by the RNA polymerase associated with ASF virions hybridized to the same DNA regions than early RNA. After hybridization selection with DNA restriction fragments and translation in reticulocyte lysates the RNA synthesized in vitro produced the same proteins as early RNA. These results suggest that early RNA is synthesized in the infected cells by the virion-associated RNA polymerase. Maps of early and late proteins of ASF virus were constructed by cell-free translation of early or late RNAs selected by hybridization to cloned restriction fragments of virus DNA. About 100 early and 100 late polypeptide bands were mapped on the ASF virus genome.

Cell Line↗
PubMed1984

Molecular cloning of African swine fever virus DNA.

African swine fever virus DNA (about 170 kbp) was cleaved with the restriction endonuclease EcoRI and most of the resulting 31 fragments were cloned in either the phage vector lambda WES lambda B or the plasmid pBR325. Three fragments were not cloned in those vectors, the largest fragment EcoRI-A (21.2 kbp) and the two crosslinked terminal fragments, EcoRI-K' and D'. Endonuclease SalI cut fragment EcoRI-A into three pieces which were cloned in plasmid pBR322. The two terminal EcoRI fragments were cloned after removal of the crosslinks with nuclease S1 and addition of EcoRI linkers to the fragment ends. The complete library of the cloned fragments accounted for about 98% of ASF virus genome, the missing sequences being those removed by the nuclease S1 in the process of cloning the terminal fragments.

African Swine Fever Virus↗
PubMed1984

Restriction site map of African swine fever virus DNA.

Treatment of African swine fever virus DNA (about 170 kbp) with the restriction endonucleases SalI, EcoRI, KpnI, PvuI, and SmaI yielded 14, 31, 17, 13, and 11 fragments, respectively. The order of the restriction fragments produced by each nuclease was established by identifying the crosslinked EcoRI and SalI terminal fragments and then finding overlapping fragments. The five restriction fragment maps were integrated into a single map by locating SalI, KpnI, PvuI, and SmaI sites in cloned EcoRI fragments, and orienting each fragment in the overall map.

African Swine Fever Virus↗
PubMed1984

Terminal and internal inverted repetitions in African swine fever virus DNA.

An electron microscopic analysis of the heteroduplexes formed by reannealing denatured terminal restriction fragments of African swine fever (ASF) virus DNA showed Y-shaped molecules with a 2.1-kilobase-pair-long double-stranded tail and two single-stranded arms. This indicated that ASF virus DNA has terminal inverted repetitions with a length of 2.1 kbp. In addition, under less restrictive hybridization conditions, most of the heteroduplexes showed a 0.13 kbp-long internal double-stranded region, separated from the long terminal repeat by a single-stranded asymmetric loop. These internal inverted repetitions did not match well, since the heteroduplexes melted under conditions where those of the terminal repetitions were stable. In the terminal fragments EcoRI-K' and D', the distance between the terminal and the internal inverted repetitions was 2.4 and 0.4 kbp, respectively.

African Swine Fever Virus↗
PubMed1978

Requirements of BHK cells for the exit from different quiescent states.

We have investigated the kinetics of exit from the resting state of BHK cells which had been arrested by isoleucine deprivation, serum starvation, or high temperature in the case of three ts G1 mutants. In addition, we have studied the effect of imposing a secondary deprivation on cells which had been released from one of the above mentioned blocks. The results obtained show that the quiescent states reached by BHK cells following serum or isoleucine deprivation cannot be differentiated on the basis of the exit kinetics from Smith and Martin's probabilistic A-state. Nevertheless, the response of cells to secondary deprivation is different, depending on the nature of the primary arresting condition used, reflecting physiological differences between the different resting states. A model is presented which postulates that cycle transition specific genes require the presence of different proliferative agents for their expression.

Cell Cycle↗
PubMed1978

Inhibition of herpes simplex virus type 1 replication in temperature-sensitive cell cycle mutants.

Herpes simplex virus type 1 DNA synthesis and infections progeny production were studied in five different conditional hamster (BHK-21) cell cycle mutants. At the nonpermissive temperature (39.5 degrees C), both events were strongly inhibited in four of these cell lines. The degree of inhibition was a reproducible characteristic of each cell mutant and in two cases was dependent upon the multiplicity of infection. Experiments involving shifts to the nonpermissive temperature at least 3 h postinfection at 33.5 degrees C suggested that the defects in viral replication were not due to faulty adsorption, penetration, or uncoating, whereas experiments involving shifts of infected cells from the nonpermissive temperature to 33.5 degrees C revealed the reversible nature of the inhibition.

Animals↗
PubMed1977

Suppression of production of mouse 28S ribosomal RNA in mouse-human hybrids segregating mouse chromosomes.

Mouse-human somatic cell hybrids that lose (segregate) human chromosomes produce only mouse 28S ribosomal RNA even when they retain copies of the human chromosomes that contain the genes for 28S ribosomal RNA. In contrast, mouse-human hybrid cells that segregate mouse chromosomes produce only human 28S ribosomal RNA even when they have retained copies of mouse chromosomes that contain the 28S ribosomal RNA genes.

Animals↗
PubMedDate not supplied

Prognostic value of serum beta 2 microglobulin in primary gastric lymphoma.

Sixty-eight previously untreated patients with primary gastric non-Hodgkin's lymphoma (NHL) available for analysis, were entered in a study in which the prognostic significance of serum beta 2 microglobulin levels were evaluated. The serum beta 2 microglobulin was the most significant prognostic factor. Patients with high levels (greater than 3.5 micrograms/mL) had a relapse-free survival (RFS) of 36 months, while the median RFS has not been reached in patients with normal levels (p less than 0.001). The 5-year survival was 80 per cent for patients with normal levels, statistically significant when compared to patients with high levels: 38 per cent (p less than 0.001). Serum beta 2 microglobulin should be included in the initial staging of patients with primary extranodal NHL and patients with high levels should be treated more aggressively.

Age Factors↗
PubMedDate not supplied

Angiocentric T-cell lymphoma of the nose, paranasal sinuses and hard palate.

Sixty-five cases of malignant lymphoma of the nose, paranasal sinuses and hard palate were retrospectively analysed to identify the presence or absence of angiocentric lesions. We observed that the 23 patients with angiocentric lesions had a worse prognosis with a shorter duration of response and also a shorter duration of survival, compared with 42 cases of malignant lymphoma of the same anatomical region but without angiocentric lesions. Patients with angiocentric lymphoma were associated with other bad prognostic factors such as elevated levels of lactic dehydrogenase and beta 2 microglobulin, local bone destruction and lymphopenia. Immunophenotyping studies showed that most patients with angiocentric lesions had T cell lymphomas (18 of 23, 78 per cent). We believe that patients with angiocentric T cell lymphomas of the nose, paranasal sinuses and hard palate represent a distinctive clinico-pathological entity with different clinical presentation and outcome. Patients with angiocentric T cell lymphomas had frequent relapse at extranodal sites and combined therapy should be considered as the initial therapeutic approach.

Adult↗
PubMedDate not supplied

[The role of radiotherapy in the early stages of Hodgkin's disease].

The outcome of treatment for a first relapse in early stages (IA and IIA) of Hodgkin's disease after primary radiotherapy was analyzed in 86 patients. They received total nodal radiotherapy (TNR) as the primary treatment. Survival was used as the major endpoint. Median follow-up was 13.1 years. Duration of first complete remission was 60% for patients in stage IA and 39% for patients in stage IIA (p < .01). At 10-years, the survival for patients in stage IA was 78% and only 55% for patients in stage IIA (p < .01). A risk factor analysis showed that the presence of stage IIA and bulky disease (adenopathy > 7 cm) were associated with a worse prognosis. We believe that the use of TNR as initial treatment in early stages of Hodgkin's disease should be considered in patients in stage IA and without bulky disease. Patients in stage IIA and risk factors, such as bulky disease, should be treated with more aggressive therapeutic regimens.

Adolescent↗