[HTLV-III in patients in a hemodialysis program].
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Adult↗
Biomedical subjects
M Salas
Publications and source records attributed to M Salas.
Effect of interleukin-2 on the manifestation and growth of acetoxymethyl-methylnitrosamine-induced colorectal rat adenocarcinoma.
The effect of highly purified human interleukin-2 (IL-2) was assessed on acetoxymethyl-methylnitrosamine(AMMN)-induced colorectal Sprague-Dawley rat adenocarcinoma. Treatment was given for 5 weeks and started 5 weeks after a period of 10 weeks intrarectal administration of 2 mg/kg of AMMN once a week. Animals which showed no evidence of tumors by endoscopical examination of the gut were given 10,000 units/kg of IL-2 s.c. into the dorsal region 5 days a week. Blood samples were analyzed from half of the animals before and 72 h after the end of the treatment. The median tumor volume and the median tumor number per rat were lower in the treated group than in the control. A significant decrease in response to two mitogens (PHA, Con-A) was seen in tumor-bearing rats concomitantly with the tumor growth. The immunological suppression was not restored by treatment with IL-2. No differences in natural killer activity or interferon levels were detected between the control and the treated group. These data indicate some antitumor effect of IL-2 given before the manifestation of tumors in AMMN-induced colorectal rat adenocarcinoma.
Adenocarcinoma↗
Undernutrition induced by early pup separation delays the development of the thalamic reticular nucleus in rats.
A Golgi-Cox study was conducted in neurons of the reticular and lateralis thalamic nuclei in normally and early undernourished Wistar rats at 12, 20, and 30 days of age. In a total of 630 neurons the cell body and the dendritic field areas, as well as the number of dendritic prolongations from camera lucida drawings were quantitated. A general and significant reduction in most reticular thalamic nucleus measurements of early-food-deprived rats was observed compared with control littermates. Additionally, reticular thalamic cells in both normal and neonatally underfed rats exhibited a progressive decline, particularly in cell body area with increasing age. In contrast, the lateral thalamic nucleus did not show significant differences between groups when similar neuronal measurements were carried out. The reticular thalamic nucleus is normally related to the control of sensory afferent transmission, and early food deprivation interferes with the growing process of this nucleus. Therefore the present data support the hypothesis that noxious perinatal environmental influences may result in a maturational deficiency of central nervous system modulatory mechanisms.
Animals↗
Effect of aphidicolin and nucleotide analogs on the phage phi 29 DNA polymerase.
The drugs aphidicolin and the nucleotide analogs butylanilino dATP, butylphenyl dGTP, and butylphenyl rGTP inhibited the protein-primed replication of phi 29 DNA-protein p3 in the presence of purified terminal protein p3 and phi 29 DNA polymerase p2. The effect of aphidicolin was mainly on the polymerization reaction by decreasing the rate of elongation. The nucleotide analogs inhibited both the formation of the p3-dAMP initiation complex and its further elongation, the latter being also due to a decrease in the elongation rate. When assayed with the phi 29 DNA polymerase as the only protein, all the drugs inhibited polymerization on activated DNA as well as the 3'----5' exonuclease activity of the polymerase, indicating that the target of the drugs is the phi 29 DNA polymerase itself.
Adenosine Triphosphate↗
Interaction of the bacteriophage phi 29 connector protein with the viral DNA.
The protein that forms the connector of phage phi 29, p10, binds to DNA. Apparently, p10 binding is not sequence specific. Nevertheless, the presence of the terminal protein (p3) covalently attached to the ends of phi 29 DNA produces a significant increase of p10 molecules bound to the DNA ends, thus suggesting a terminal protein-mediated recognition of DNA ends by the phage connector. As the p3-DNA complex is the substrate for phage phi 29 DNA packaging, these results may reflect a direct implication of the phage connector in the packaging process.
Bacillus subtilis↗
Signals in the phi 29 DNA-terminal protein template for the initiation of phage phi 29 DNA replication.
The protein-free terminal fragments HindIII B and L, from the left and right ends of phi 29 DNA, respectively, but not internal fragments of similar size, were active as templates in the formation of the p3-dAMP initiation complex in an in vitro system containing purified phi 29 terminal protein p3 and DNA polymerase p2, although the activity was lower than that obtained with the phi 29 DNA-p3 complex. These results indicate the existence of specific sequences at the ends of phi 29 DNA that allow the initiation of phi 29 DNA replication. The template activity of the protein-free terminal fragments was size dependent. The protein-free single strands of the HindIII L fragment were much less active than the corresponding double-stranded fragment. Terminal protein-DNA complexes of phages PZA and phi 15, with a terminal protein closely related to the phi 29 protein p3, were more active as templates in the initiation reaction with the purified phi 29 proteins than the corresponding protein-free DNAs, as it happens in the case of phi 29. However, the terminal protein-DNA complexes of phages Nf, B103, and GA-1, with a terminal protein less related or unrelated to the phi 29 protein p3, were essentially inactive and became active after removal of the parental terminal protein. These results strongly suggest that the parental terminal protein is the major signal in the template for the initiation of phi 29 DNA replication.
Bacillus subtilis↗
Cloning and template activity of the origins of replication of phage phi 29 DNA.
A 73-bp fragment from the left end of phi 29 DNA and a 269-bp fragment from the right end have been cloned in plasmids pPLc28 and pKK223-3, respectively, after removal of the terminal protein p3 by treatment with piperidine. In addition, the 73- and 269-bp fragments were cloned together in plasmid pKK223-3 in such a way that the two termini of phi 29 DNA were joined. Treatment of the latter recombinant plasmid with AhaIII releases several fragments, two of which contain the phi 29 DNA terminal sequences at the DNA end. These two fragments initiated replication specifically at the ends of the DNA giving rise to the formation of the p3-dAMP complex. The activity was about 15% of that obtained with phi 29 DNA-protein p3. All remaining recombinant plasmids were essentially inactive when tested as templates either in circular form or after cutting in such a way that placed the origin of phi 29 DNA replication close but not at the DNA end.
Base Sequence↗
Initiation of phage phi 29 DNA replication by mutants with deletions at the carboxyl end of the terminal protein.
Series of deletions at the C end of p3, the phage phi 29 DNA terminal protein (TP), have been constructed and characterized. Measurements of the activity of those deletion mutants in the formation of the p3-dAMP initiation complex in vitro indicate the need of an intact C-end for the normal TP primer function in DNA replication. It appears that the region at the C-end between aa 240 and 262 of p3, or part of it, might be essential for the normal TP function.
Amino Acid Sequence↗
Bacillus subtilis phage phi 29 main promoters are efficiently recognized in vivo by the Streptomyces lividans RNA polymerase.
A DNA fragment from the Bacillus subtilis phage phi 29, containing the main early and late viral promoters, has been inserted upstream of the aminoglycoside phosphotransferase gene (neo) derived from the transposon Tn5 and present in a Streptomyces lividans promoter-probe plasmid. The phi 29 promoters are specifically recognized by the S. lividans RNA polymerase which initiates transcription in vivo at the same sites utilized in B. subtilis. Moreover, the viral promoters efficiently direct the synthesis of high levels of the APHII enzyme in S. lividans.
Bacillus subtilis↗
Formation of a covalent complex between the terminal protein of pneumococcal bacteriophage Cp-1 and 5'-dAMP.
Incubation of extracts of Cp-1-infected Streptococcus pneumoniae with [alpha-32P]dATP produced a labeled treatment with micrococcal nuclease and sensitive to treatment with proteinase K. Incubation of the 32P-labeled protein with 5 M piperidine for 4 h at 50 degrees C released 5'-dAMP, indicating that a covalent complex between the terminal protein and 5'-dAMP was formed in vitro. When the four deoxynucleoside triphosphates were included in the reaction mixture, a labeled complex of slower electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels than the terminal protein-dAMP complex was also found, indicating that the Cp-1 terminal protein-dAMP complex can be elongated and, therefore, that it is an initiation complex. Treatment of the 32P-labeled terminal protein-dAMP complex with 5.8 M HCl at 110 degrees C for 2 h yielded phosphothreonine. These results, together with the resistance of the terminal protein-DNA linkage to hydroxylamine, suggest that the Cp-1 terminal protein is covalently linked to the DNA through a phosphoester bond between L-threonine and 5'-dAMP, namely, a O-5'-deoxyadenylyl-L-threonine bond.
Bacteriophages↗
In vivo transcription of bacteriophage phi 29 DNA: transcription initiation sites.
The initiation sites of the RNA transcripts synthesized in vivo in Bacillus subtilis infected with bacteriophage phi 29 have been mapped by S1 protection experiments. Nine transcription initiation sites were localized along the entire phi 29 genome, close to previously reported B. subtilis and Escherichia coli RNA polymerase-binding sites. Eight of these sites corresponded to early transcription and only one corresponded to late transcription. By using 5'-end-labeled RNA, four of the early sites and the late one were shown to be the main sites where initiation of transcription occurs in vivo in the phi 29 genome.
Bacillus subtilis↗
Location of the serine residue involved in the linkage between the terminal protein and the DNA of phage phi 29.
B. subtilis phage phi 29 has a terminal protein, p3, covalently linked to the 5' ends of the DNA through a phosphodiester bond between a serine residue and 5'-dAMP. This protein acts as a primer in DNA replication by forming an initiation complex with the 5'-terminal nucleotide dAMP. The amino acid sequence of the terminal protein, deduced from the nucleotide sequence of gene 3, showed the presence of 18 serine residues in a total of 266 amino acids. In this paper we have identified the serine involved in the linkage with the DNA as the residue 232, located close to the C-terminus of the molecule. This result was obtained by amino acid analysis of the peptide that remains linked to the DNA after proteinase K digestion of the terminal protein-phi 29 DNA complex and automated Edman degradation of the corresponding [125I]-labeled tryptic peptide. Prediction of the secondary structure of the terminal protein suggested that the serine residue involved in the linkage with the DNA is placed in a beta-turn, probably located on the external part of the molecule, as indicated by hydropathic values.
Amino Acid Sequence↗
Overproduction and purification of protein P6 of Bacillus subtilis phage phi 29: role in the initiation of DNA replication.
A phi 29 DNA fragment containing gene 6, required for DNA replication, has been cloned in plasmid pPLc28 under the control of the PL promoter of phage lambda. A polypeptide with an electrophoretic mobility close to that of p6 was labelled with 35S-methionine after heat induction. This protein, representing about 4% of the total E. coli protein after 1 h of induction, was obtained in a highly purified form. The protein was characterized as p6 by amino acid analysis and NH2-and COOH-terminal sequence determination. Protein p6 has an apparent molecular weight of 23,600, suggesting that the native form of the protein is a dimer. The purified protein p6 stimulated the protein-primed initiation of phi 29 DNA replication when added to purified proteins p2 (phi 29-coded DNA polymerase) and p3 (terminal protein).
Amino Acid Sequence↗
Characterization of a 3'----5' exonuclease activity in the phage phi 29-encoded DNA polymerase.
Purified protein p2 of phage phi 29, characterized as a specific DNA polymerase involved in the initiation and elongation of phi 29 DNA replication, contains a 3'----5' exonuclease active on single-stranded DNA, but not on double-stranded DNA. No 5'----3' exonuclease activity was found. The 3'----5' exonuclease activity was shown to be associated with the DNA polymerase since 1) the two activities were heat-inactivated with identical kinetics and 2) both activities, present in purified protein p2, cosedimented in a glycerol gradient.
Bacillus subtilis↗
Role of Langerhans cells in the infection of the guinea-pig epidermis with foot-and-mouth disease virus.
In guinea-pig infected with foot-and-mouth disease virus (FMDV), Langerhans cells in the foot pads increase in number and show viral antigens 24 hours post-inoculation, preceding appearance of virus in epithelial cells and vesiculation. This observation suggests that Langerhans cells may be engaged in virus transport from the blood to the non vascularized epidermis.
Animals↗
Inverted terminal repeats and terminal proteins of the genomes of pneumococcal phages.
The nucleotide (nt) sequence at the ends of the genomes of the Streptococcus pneumoniae phages Cp-5 and Cp-7 has been determined and compared with the corresponding sequence of phage Cp-1. The genomes of phages Cp-5 and Cp-7 have inverted terminal repeats (ITRs) 343 and 347 bp long, respectively. In Cp-1 DNA the ITR is 236 bp long and the following 116 bp are 93% homologous. Some regions within the ITRs are conserved in the three genomes although the complete sequence of the ITRs is no more conserved than the rest of their genomes. The chromatographic behavior of their tryptic peptides suggests that the terminal proteins (TPs) of at least two of the phages are similar and that the TPs of the three pneumococcal phages differ markedly from that of the Bacillus subtilis phage psi 29.
Bacteriophages↗
The importance of surgical evaluation of patients with "Turner-like" sex chromosomal abnormalities.
Children with "pure" gonadal dysgenesis do not require abdominal explorations to remove their gonads, because the risk of development of malignancy is minimal. Children with "mixed" gonadal dysgenesis, who usually present with sexual ambiguity, need to have gonadectomy because of the high incidence of malignancy in these gonads. We present four children (three adolescents and one two year old) who presented with minimal somatic anomalies, who did not have sexual ambiguity. The prominent features were primary amenorrhea and short stature in the adolescents, and minor dysmorphic features in the small child. On the basis of these physical features, complete genetic evaluation was carried out, and a Y chromosome or an unidentifiable fragment was identified in all four cases. At exploration, bilateral genital streaks were found, and were removed. In addition to the usual microscopic features of the streaks, Leydig cells and tubular structures resembling rete testis were seen in all the gonads. In one gonad, a gonadoblastoma was found. Since this type of gonad is "at risk" for the development of gonadoblastoma, the need for complete genetic evaluation of all females with "Turner-like" chromosomal abnormalities, although phenotypically female, is emphasized. If a Y chromosome or any unusual fragment is identified, exploration should be carried out, and any gonad that is not a normal ovary should be removed.
Adolescent↗
Replication of phage phi 29 DNA with purified terminal protein and DNA polymerase: synthesis of full-length phi 29 DNA.
A system that replicates bacteriophage phi 29 DNA with protein p3 covalently attached to the two 5' ends, using as the only proteins the phi 29 DNA polymerase and the terminal protein, is described. Restriction analysis of the 32P-labeled DNA synthesized in vitro showed that all phi 29 DNA fragments were labeled. Analysis by alkaline sucrose gradient centrifugation of the DNA labeled during a 10-min pulse showed that, after a 20-min chase, about half of the DNA molecules had reached apparently full-length phi 29 DNA (approximately equal to 18,000 nucleotides). Ammonium ions strongly stimulated phi 29 DNA-protein p3 replication, the effect being due to stimulation of the initiation reaction. ATP was not required for phi 29 DNA-protein p3 replication, either in the initiation or elongation steps. The results show that the phi 29 DNA polymerase functions, not only in the formation of the p3-dAMP covalent initiation complex but also in the elongation of the latter, as the only DNA polymerase to produce full-length phi 29 DNA.
Adenosine Monophosphate↗