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C Alonso

Publications and source records attributed to C Alonso.

At least 163 records · Page 9Linked to original sources
PubMed1997

The berenil ligand directs the DNA binding of the cytotoxic drug Pt-berenil.

To determine the affinity towards DNA sequences of novel antitumor drugs in comparison with their parental compounds may lead to the design of new analogous drugs with improved antitumor activity. Thus, the affinities of Pt-berenil towards different DNA sites relative to cis-DDP and berenil drugs were analysed using DNase I footprinting and restriction endonuclease analysis. The data show that the Pt-berenil drug inhibits the cutting activity of Hind III enzyme to the same extent as the berenil ligand. In contrast, inhibition by Pt-berenil of the cutting activity of Bam HI enzyme is significantly lower than that of cis-DDP. These results indicate that although the cis-Pt(II) centres of Pt-berenil maintain certain affinity toward G + C regions, which are the main binding sequences of cis-DDP, however, the berenil ligand seems to direct the Pt-berenil molecule towards A + T regions, which are the binding sequences preferred by berenil. In fact, 1H- and 195Pt-NMR spectra of Pt-berenil:nucleoside complexes show that Pt-berenil not only covalently binds to N7 of guanosine but also to N1/N7 of adenosine.

Adenosine↗
PubMed1997

High level expression of the major antigenic African swine fever virus proteins p54 and p30 in baculovirus and their potential use as diagnostic reagents.

At present, the eradication of African swine fever (ASF) in affected countries is based only on an efficient diagnosis program because of the absence of an available vaccine. The highly antigenic ASF virus proteins p54 and p30, encoded by genes E183L and CP204L respectively, were expressed in baculovirus for diagnostic purposes. A sequence comparison analysis of these genes from different field virus strains which are geographically diverse and isolated in different years, revealed that both genes are completely conserved among the isolates. Partially purified baculovirus-expressed proteins were used in ELISA and Western blot for ASF antibody detection in sera from experimentally inoculated pigs and field sera from ASF innaparent carriers. These comparative analyses showed that p54 presents better reactivity than p30 in Western blot. However, recombinant p30 was more efficient for antibody detection by ELISA, improving the discrimination between positive and negative sera by this technique. These data suggest the convenience of using p30 as ELISA antigen, while p54 should be the selected antigen for ASF virus antibody detection by Western blot. The combined use of both antigens for serodiagnosis of ASF disease will improve the sensitivity of innaparent carriers detection, facilitating also the interpretation of the tests, and eliminating the use of ASF virus in antigen production.

African Swine Fever↗
PubMed1997

A region containing repeated elements is associated with transcriptional termination of Leishmania infantum ribosomal RNA genes.

A novel repetitive DNA element has been isolated from the Leishmania infantum genome. The 348 bp long element, designated LiR3, was found to be located downstream from the 3'-end of the ribosomal RNA (rRNA) genes. This LiR3 element has short sequences with potential to form stem-loop structures similar to those of the bacterial rho-independent transcriptional terminators. Given both the structural features and the genomic location of this element we searched for a possible functional implication of these structures in the termination of rRNA transcription. Nuclear run-on assays indicated that indeed there is a transcriptional blockage associated with the LiR3 element. Several chi-like elements, resembling the recombination-promoting sites of Escherichia coli, were identified within the sequences associated with the stem-loop structures. A possible implication of these chi-like elements in rRNA gene conversion events is discussed.

Animals↗
PubMed1997

Modulation of immune cell populations and activation markers in the pathogenesis of African swine fever virus infection.

African swine fever (ASF) virus induces immune cell alterations that may be detected by changes in peripheral blood cells phenotypic antigens and activation markers which were examined by flow cytometry, analyzing both cell proportion and/or expression intensity of superficial antigens. These studies were conducted in pigs with experimental acute of chronic ASF infection to determine whether changes among important surface activation markers and phenotypic antigens, and their correlative lymph node status, reflected similar or disparate aspects of immune pathology. In acute infection produced by virulent viruses, macrophage and B lymphocyte populations decreased in peripheral blood after a short activation period at the beginning of the infection. A significative decrease of interleukin 2 receptor (IL 2R) expression was also observed in those pigs. These variations correlated with lymph node cell depletion due to an intense lymphoid cell death by apoptosis, affecting mainly the B lymphocyte subpopulation as determined by immunohistochemistry. Nevertheless, pigs infected with an attenuated isolate undergoing chronic persistent infection, presented a distinct pattern of modification, according with a different clinicopathological evolution. Changes consisted in systemic immune activation coincident with the highest viremia titer, with an augmentation in CD8+ T lymphocyte, macrophage, and B cell populations, and MHC (major histocompatibility complex) antigens. Percentage elevation of circulating immune subpopulations was accompanied by cell accumulation with lymphoid hyperplasia but a conserved distribution of B lymphocytes in lymphoid organs of chronically infected pigs.

Acute Disease↗
PubMed1997

Characterization of an interspersed repetitive DNA element in the genome of Trypanosoma cruzi.

We report the molecular characterization of a middle repetitive DNA sequence, named C6, isolated from the Trypanosoma cruzi genome. C6 appears to be a composite repeated element since 3 subregions may be defined within it on the basis of sequence similarities with other T. cruzi genomic sequences. Sequences homologous to C6 are interspersed in the genome and can be mapped out on most chromosomal bands of different T. cruzi. strains. The copy number of the C6 element is about 1000 per haploid genome. Given the species specificity and different genomic distribution of C6 homologous sequences among the T. cruzi strains the C6 element could be a useful probe for diagnosis and typing of parasites. C6 is a polymorphic marker with potential as a tool for physical mapping of the T. cruzi genome.

Animals↗
PubMed1997

Agonistic anti-Fas antibodies induce glomerular cell apoptosis in mice in vivo.

Recent studies suggest that apoptotic cell death regulates the cell complement in glomerular diseases. However, little is-known about the factors that promote glomerular cell apoptosis. Activation of the Fas receptor by the Fas ligand or agonistic antibodies triggers apoptosis in some cell types that express Fas. Cultured human mesangial cell are among the cells that undergo apoptosis upon Fas activation, but it is unclear whether mesangial cells are sensitive to death induced by Fas in vivo. We have now explored the role of Fas in experimental glomerular injury. Murine mesangial cells in culture express fas and undergo apoptosis when stimulated with the Jo2 agonistic anti-Fas mAb. A fas mRNA transcript is present in normal murine kidney and freshly isolated glomeruli. Balb-c mice developed hematuria and proteinuria within 24 hours of the intraperitoneal injection of 10 micrograms Jo2 anti-Fas mAb. In addition to liver cell apoptosis, glomerular cell apoptosis and mesangial cell depletion were evident in the kidney at three hours and more pronounced at 24 hours. Glomerular and liver injury were not prevented by decomplementation. These data suggest that Fas activation in vivo by specific antibodies induces glomerular and mesangial cell apoptosis in mice.

Animals↗
PubMed1997

Mapping of the antigenic determinants of the Leishmania infantum gp63 protein recognized by antibodies elicited during canine visceral leishmaniasis.

The gp63 gene encoding the major surface antigen of Leishmania infantum has been cloned and sequenced. In spite of the overall sequence homology with the gp63 genes from other Leishmania species, particularly with the constitutively expressed Leishmania chagasi Gp63 gene, the carboxy-terminal ends of these genes are clearly divergent (62% homology). To study the prevalence of anti-gp63 antibodies in the sera from dogs with visceral leishmaniasis, a recombinant L. infantum gp63 protein was expressed in Escherichia coli. It was found that 100% of the sera from these dogs recognized the recombinant gp63 protein, suggesting that it must function as a potent B cell immunogen during natural canine visceral leishmaniasis. However, heterogeneity in the level of response was observed. Fine mapping of the antigenic determinants was performed by means of 6 overlapping subfragments of the gp63 protein and by the use of a library of synthetic peptides. The data showed that there is some degree of immunological restriction in the recognition of the protein since reactivity was observed preferentially against the most divergent region. The epitope mapping of this region showed 2 immunodominant peptides the response to which seems to be preferentially of the IgG2 type.

Amino Acid Sequence↗
PubMed1997

[Medical liability and unintentional offenses in professional practice].

Malpractice and negligence lawsuits against physician have significantly increased lately. Therefore, the legal and ethical setting of this problem in our country must be specified. There are multiple causes that lead to attribute the responsibility of a determinate damage to medical practice, but the most important is an inadequate medical-patient-family relationship. Lawsuits are transcendental for physicians and affect them in several ways. Several measures are proposed to reduce them. Considering the increasing importance of solidarity and shared compensations, the responsibility of institutions and other professionals, besides physicians, is analyzed.

Chile↗
PubMed1996

African swine fever virus gene A179L, a viral homologue of bcl-2, protects cells from programmed cell death.

The African swine fever virus (ASFV) open reading frame A179L, which is similar to the human proto-oncogene bcl-2, has been cloned and expressed in vaccinia virus under control of the pEIL synthetic early/late promoter. The A179L gene product prevented cell death in HeLa and BSC-40 cells doubly infected with another recombinant vaccinia virus expressing the interferon-induced double-stranded RNA-activated protein kinase (p68 kinase), which activates a rapid cell death characteristic of apoptosis. This finding suggests that the A179L gene has a function similar to that of bcl-2 in preventing apoptosis and may play an important role during productive ASFV infection.

African Swine Fever Virus↗
PubMed1996

Modification of the recognition of restriction sites of plasmid DNA by the antitumor drug Pt-pentamidine.

The rate of binding of the antineoplastic drugs Pt-pentamidine [(cis-PtCl2)3(pentamidine)3][PtCl4]2 and cis-DDP [cis-diamminedichloroplatimum(II)] to pUC8 DNA, as well as the effect of the binding of these platinum compounds on the cutting effectiveness of Bam HI, Hind III, and Sal I restriction endonucleases, were determined by flameless atomic absorption spectroscopy and gel electrophoresis, respectively. The results show that covalent DNA platination is 12% to 22% lower in DNA: Pt-pentamidine complexes than in DNA: cis-DDP at the same molar rate of platinum/nucleotide, and the number of Pt-pentamidine molecules bound to DNA is significantly lower in Pt-pentamidine: DNA complexes than in cis-DDP: DNA complexes. Although both compounds inhibit Bam HI cleavage of pUC8 DNA, Pt-pentamidine does not prevent the cutting activity of Hind III, in contrast with cis-DDP. Neither cis-DDP nor Pt-pentamidine inhibits the cutting activity of Sal I, whose recognition sequence neighbors the Bam HI and Hind III sites.

DNA↗
PubMed1996

Organization, transcription and regulation of the Leishmania infantum histone H3 genes.

The genomic organization and transcription of the genes encoding the histone H3 of the protozoan parasite Leishmania infantum have been studied. It was found that there are multiple copies of the histone H3 genes distributed in chromosomal bands XIX and XIV. The nucleotide sequence of two of the L. infantum H3 genes, each one located in a different chromosome, is reported. Although the nucleotide sequence of the coding region of both genes is identical, the sequence of the 3' untranslated region is highly divergent. It was found also that there exist two different size classes of histone H3 transcripts, each one derived from a different gene, and that they are polyadenylated. The steady-state level of the transcripts dramatically decreases when the parasites enter the stationary phase of growth, suggesting a mode of regulation which is linked to the proliferation status of the cell. Unlike the replication-dependent histones, the L. infantum H3 mRNA levels do not decrease after treatment with DNA synthesis inhibitors. A comparative analysis of the sensitivity of the histone mRNA levels to DNA inhibition in the parasites L. infantum and Trypanosoma cruzi revealed the existence of different control mechanisms in histone expression in these two phylogenetically related protozoan parasites.

Amino Acid Sequence↗
PubMed1996

Interleukin 2 is a lectin that associates its receptor with the T-cell receptor complex.

To determine the nature of the mechanism by which the binding of interleukin-2 (IL-2) to its receptor (IL-2R beta) induces IL-2R beta phosphorylation by the tyrosine kinase p56lck associated with the T-cell receptor (TCR) complex, we investigated the possibility that this mechanism was due to the putative lectin activity of IL-2 ([Sherblom, Sathyamoorthy, Decker and Muchmore (1989) J. Immunol. 143, 939-944]. Here we demonstrate that IL-2 is a calcium-independent lectin specific for oligomannosidic N-glycans with five and six mannose residues. This lectin activity is preserved after binding of IL-2 to IL-2R beta. IL-2 behaves as a bifunctional molecule that associates IL-2R beta with specific glycoprotein ligands of the TCR complex including a glycosylated form of CD3.

Carbohydrate Sequence↗
PubMed1996

Oligomannosides or oligosaccharide-lipids as potential substrates for rat liver cytosolic alpha-D-mannosidase.

We have previously reported the substrate specificity of the cytosolic alpha-D-mannosidase purified from rat liver using Man9GlcNAc, i.e. Man alpha 1-2Man alpha 1-3(Man alpha 1-2Man alpha 1-6)Man alpha 1-6(Man alpha 1-2Man alpha 1-2Man alpha 1-3) Man beta 1-4G1cNAc, as substrate [Grard, Saint-Pol, Haeuw, Alonso, Wieruszeski, Strecker and Michalski (1994) Eur. J. Biochem. 223, 99-106]. Man9 G1cNAc is hydrolysed giving Man5GlcNAc, i.e. Man alpha 1-2 Man alpha 1-2Man alpha 1-3(Man alpha 1-6)Man beta 1-4GlcNAc, possessing the same structure as the oligosaccharide of the dolichol pathway formed in the cytosolic compartment during the biosynthesis of N-glycosylprotein glycans. We study here the activity of the purified cytosolic alpha-D-mannosidase towards the oligosaccharide-diphosphodolichol intermediates formed during the biosynthesis of N-glycans, and also towards soluble oligosaccharides released from the endoplasmic reticulum which are glucosylated or not and possessing at their reducing end either a single N-acetylglucosamine residue or a di-N-acetylchitobiose sequence. We demonstrate that (1) dolichol pyrophosphate oligosaccharide substrates are poorly hydrolysed by the cytosolic alpha-D-mannosidase; (2) oligosaccharides with a terminal reducing di-N-acetylchitobiose sequence are not hydrolysed at all; (3) soluble oligosaccharides bearing a single reducing N-acetylglucosamine are the real substrates for the enzyme. These results suggest a role for alpha-D-mannosidase in the catabolism of glycans released from the endoplasmic reticulum rather than in the regulation of the biosynthesis of asparagine-linked oligosaccharides.

Animals↗
PubMed1996

Effects of cardiopulmonary bypass temperature on pulmonary gas exchange after coronary artery operations.

BACKGROUND: Pulmonary dysfunction is one aspect of the postoperative morbidity associated with cardiopulmonary bypass. Normothermic systemic perfusion can result in shorter intubation times, which have been attributed to improved pulmonary gas exchange, but the influence of perfusion temperature on pulmonary gas exchange itself is not known. METHODS: Pulmonary gas exchange was assessed using alveolar-arterial oxygen pressure gradients in 45 patients undergoing routine coronary revascularization who were randomized to undergo cardiopulmonary bypass at 28 degrees C, 32 degrees C, or 37 degrees C. This was part of a more comprehensive study of the effects of temperature on bodily systems. The gradients were estimated preoperatively with the patients breathing air, again over a period between 2 and 4 hours postoperatively during mechanical ventilation with three different oxygen concentrations (30%, 40%, and 60%), and again 1 hour after extubation while breathing the same three oxygen concentrations. RESULTS: Preoperative alveolar-arterial oxygen pressure gradients on air were 24.4 +/- 8.2 mm Hg (mean +/- standard deviation) (28 degrees C), 24.5 +/- 20.4 mm Hg (32 degrees C), and 20.5 +/- 9.5 mm Hg (37 degrees C). Postoperatively, during ventilation and after rewarming, the gradients increased with the increase in inspired oxygen fraction concentrations (30% to 60%) from 67.1 +/- 12.0 mm Hg to 193.1 +/- 30.5 mm Hg (28 degrees C), from 76.4 +/- 20.6 mm Hg to 246.7 +/- 47.7 mm Hg (32 degrees C), and from 79.0 +/- 18.0 mm Hg to 222.9 +/- 40.5 mm Hg (37 degrees C), respectively. A similar pattern was noted 1 hour after extubation, when the gradients increased from 72.4 +/- 12.5 mm Hg to 256.6 +/- 26.5 mm Hg (28 degrees C), from 75.7 +/- 13.9 mm Hg to 252.7 +/- 38.3 mm Hg (32 degrees C), and from 69.1 +/- 19.3 mm Hg to 253.1 +/- 33.0 mm Hg (37 degrees C). There were no significant differences in alveolar-arterial oxygen pressure gradient between the three groups during ventilation or after extubation. CONCLUSIONS: Cardiopulmonary bypass perfusion temperature does not influence alveolar-arterial oxygen pressure gradients in the first 12 hours after routine coronary artery bypass grafting in patients with uncompromised pulmonary and left ventricular function.

Carbon Dioxide↗
PubMed1996

Cis-Dichloro(diaminosuccinate diethyl ester)palladium (II) as Pd(II)/Pt(II) model compound for DNA-binding and antitumor properties: solution equilibria of their aqua-, hydroxo-, and/or chloro-species.

Cis-Dichloro(diaminosuccinic acid)palladium(II), cis-[Pd(H2dasa)Cl2] (I), or cis-dichloro(diaminosuccinate diethyl ester)palladium(II), cis-[Pd(Et2dasa)Cl2] (II) reacts with two equivalents of AgClO4 to give insoluble Pd(dasa) or an aqueous solution of [Pd(Et2dasa) (H2O)2](ClO4)2, respectively. Three solutions of this salt were titrated with NaOH (I = NaClO4 (0.15M),37 degrees C), and 133 E(H+) data (3.5 < or = pH < or = 7) were treated by SUPERQUAD to fit log beta pqr of cis-aquahydroxo-(pqr = 10-1, -5.25(3)) and di-mu-hydroxo-species (20-2, -6.55(1)). At pH > 7 the ester hydrolysis prevents the calculation of log beta 10-2 for the cis-dihydroxo-complex. Another three solutions of such salt were titrated (I = 0.15M (NaClO4), 37 degrees C) with NaOH and NaCl simultaneously using two potentiometric systems (which measure H+ or Cl-). From 147 E(H+) and E(Cl-) data pairs and the above fixed log beta pqr, SUPERQUAD calculations yield log beta pqr for cis-chloro-aqua (pqr = 110, 3.65(1)), cis-chloro-hydroxo (11-1, -2.68 (4)), and cis-dichloro-species (120, 5.86(3)). Simulated and experimental titrations are in good agreement. Circular dichroism spectra of native DNA and drug:DNA complexes suggest that cis-Pd(H2dasa) and cis-Pd(Et2dasa) chelate moieties induce an opening and rotation of the stacked bases in the double helix. This finding is explained by the abundance of each one and of the total neutral and charged species of II in the tested CD solution.

Amino Acids, Diamino↗