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C Alonso

Publications and source records attributed to C Alonso.

At least 145 records · Page 8Linked to original sources
PubMed1998

Use of somatostatin analogue scintigraphy in the localization of recurrent medullary thyroid carcinoma.

Detection of recurrence of medullary thyroid carcinoma (MTC) remains a diagnostic problem. Increased serum tumour marker levels frequently indicate recurrence while conventional imaging techniques (CIT) are non-diagnostic. In this study, we performed indium-111 octreotide scintigraphy and CIT in a series of 20 patients with MTC presenting with elevated serum tumour markers after surgery. 111In-octreotide whole-body studies detected 15 pathological uptake foci in 11 of the 20 patients studied and CIT detected 17 lesions in 11 of the 20 patients. Ten patients underwent reoperation, five of them with positive 111In-octreotide scintigraphy and CIT and two with positive isotopic exploration and negative CIT. Surgical findings demonstrated that the results of isotopic study and CIT had been false-positive for MTC in one case (sarcoidosis). The six patients with true-positive 111In-octreotide studies had significantly higher basal calcitonin (CT) and carcinoembryonic antigen (CEA) levels than the patients with negative isotopic studies. The expression of somatostatin receptor (SSTR) subtypes by PC-PCR could be investigated in four cases with a positive isotopic study. Among the three cases with a true-positive study, SSTR2, the SSTR subtype that preferentially binds to the somatostatin analogue octreotide, was detected in two, SSTR5 was demonstrated in the three, and SSTR3 was detected in one. No subtype of SSTR was detected in the case with a final diagnosis of sarcoidosis. We conclude that 111In-octreotide has limited sensitivity in detecting recurrence in patients with MTC, although its sensitivity may improve with high serum CT levels. This radionuclide imaging technique should be employed when conventional imaging techniques are negative or inconclusive or when the presence of somatostatin receptors may provide the basis for treatment with somatostatin analogues.

Adult↗
PubMed1998

Programmed cell death in the pathogenesis of rabbit hemorrhagic disease.

Rabbit hemorrhagic disease is a rapidly lethal infection caused by a calicivirus, characterized by acute liver damage and disseminated intravascular coagulation (DIC). Following morphological criteria and using a specific in situ labeling technique, we have found that liver cell death induced upon infection is due to apoptosis, and that programmed cell death is a constant feature in rabbits experimentally infected with RHDV. The process affected mainly hepatocytes, but also macrophages and endothelial cells presented morphologic hallmarks of apoptosis, expressing all these cell types viral antigens as determined by immunohistochemistry. The occurrence of programmed cell death was correlated with the appearance of the RHDV induced pathology in tissues by DNA fragmentation detection in situ. Hepatocyte apoptosis produced extensive parenchymal destruction causing a lethal, acute fulminant hepatitis that is characteristic of RHD. Apoptosis of intravascular monocytes and endothelial cell was observed together with fibrin thrombi in blood vessels. Since apoptotic cells are known sites of enhanced procoagulant activity, apoptosis of these cell populations might constitute a first step in the pathogenesis of DIC and a common pathway to other viral hemorrhagic fevers. In conclusion, apoptosis in RHD may be determinant in the development of the pathogenesis of this disease.

Animals↗
PubMed1998

Purification, characterization, and partial sequencing of two new allergens of Olea europaea.

BACKGROUND: The inhalation of olive (Olea europaea) pollen is an important cause of allergic respiratory diseases in southern Europe and California. OBJECTIVE: The aims of this study were to characterize the allergenic composition of O. europaea pollen collected in California and to purify two important allergens. METHODS: One hundred grams of O. europaea pollen was extracted dialyzed in 10 kd cut-off membranes and lyophilized. Allergen characterization was done by sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting. Two allergens were isolated by gel filtration, ion exchange, and hydrophobic interaction chromatography and sequenced. RESULTS: Ole e 4 has an apparent molecular weight, under reducing conditions, of 32 kd and pIs between 4.65 and 5.1. The N-terminal was blocked and the analysis of the amino acid sequence of two internal regions revealed no homology with other known proteins. Ole e 5 has a molecular weight of 16 kd and pIs between 5.1 and 6.5. The amino acid sequence of the N-terminal showed a high degree of homology with superoxide dismutase of several plant species. Ole e 4 and Ole e 5 had an IgE binding frequency by immunoblot of 80% and 35%, respectively. CONCLUSIONS: Olive pollen extracts have a heterogeneous composition, with several important allergens. One of these allergens showed a high degree of homology with a superoxide dismutase.

Allergens↗
PubMed1998

Binuclear chloro-bridged palladated and platinated complexes derived from p-isopropylbenzaldehyde thiosemicarbazone with cytotoxicity against cisplatin resistant tumor cell lines.

Two novel dimeric chloro-bridged complexes [Pd (p-is. TSCN) (mu-Cl)]2, 2, and [Pt (p-is. TSCN)(mu-Cl)]2, 3, where p-is. TSCN = p-isopropylbenzaldehyde thiosemicarbazone, 1, have been synthesized and characterized by IR and NMR spectroscopy. The in vitro antitumor activity shown by both compounds against several human and murine cell lines sensitive and resistant to the clinically-used drug cisplatin (cis-DDP) suggests that compounds 2 and 3 may be endowed with important anticancer properties. Thus, compounds 2 and 3 not only show IC50 values in the microM range as cis-DDP but also display cytotoxic activity in tumor cell lines resistant to this drug. The analysis of the interaction of these binuclear p-is. TSCN compounds with DNA secondary and tertiary structures indicate that they form DNA interhelical cross-links, a biochemical property that may be involved in their mechanism of action.

Animals↗
PubMed1998

Palladated and platinated complexes derived from phenylacetaldehyde thiosemicarbazone with cytotoxic activity in cis-DDP resistant tumor cells. Formation of DNA interstrand cross-links by these complexes.

In the present paper we report the synthesis and characterization by 1H 13C NMR and heteronuclear 2D NMR spectroscopies of two new metallic complexes derived from phenylacetaldehyde thiosemincarbazone: Pt(C9H11N3S)Cl2, compound 2, and Pd(C9H11N3S)Cl2, compound 3. The testing of the cytotoxic activity of these compounds against several human and murine cell lines sensitive and resistant to cis-DDP suggests that compounds 2 and 3 may be considered potential anticancer agents since they exhibit 1C50 values in a microM range similar to cisplatin (cis-DDP). The cytotoxic activity of these compounds is higher in cis-DDP-resistant tumor cells than that of other antitumor drugs such as etoposide and adriamycin. On the other hand, the analysis of the interaction of compounds 2 and 3 with linear plasmid DNA indicate that both compounds, particularly compound 3, have an enhanced capacity to form DNA interstrand cross-links in comparison with cis-DDP.

Antineoplastic Agents↗
PubMed1998

Analysis of the antigenic properties of the L. infantum Hsp70: design of synthetic peptides for specific serodiagnosis of human leishmaniasis.

The 70-kDa heat shock protein (Hsp70) is a major target of the humoral immune response during Leishmania infections. In the present paper, it is shown that 84.6% of sera from mucocutaneous leishmaniasis (MCL) patients and 78.9% of sera from visceral leishmaniasis (VL) patients reacted with the L. infantum Hsp70. The mapping of the antigenic determinants indicated that this protein is highly rich in linear B-epitopes. As the complete protein cannot be used for specific serodiagnosis of VL because it is also recognized by the sera from Chagas' disease patients, a search for specific epitopes recognized by leishmaniasis patients was undertaken. A 50-mer synthetic peptide, located in the most divergent region of the protein, was found to be recognized by a high percentage of leishmaniasis sera and not recognized by chagasic sera. Such a tool would be particularly useful for serodiagnosis of leishmaniasis in geographical areas where mixed infections with Trypanosoma cruzi and Leishmania occurs.

Amino Acid Sequence↗
PubMed1998

Polymerase chain reaction procedure to detect Trypanosoma cruzi in blood samples from chronic chagasic patients.

The feasibility of DNA amplification by the polymerase chain reaction for specific detection of Trypanosoma cruzi in human blood was investigated. We have used primers flanking a 220-bp fragment of highly repetitive elements, the E13 element, in T. cruzi nuclear DNA. Only polymerase chain reaction products from blood samples of chronic chagasic patients showed several amplified fragments in 1.6% agarose gels stained with ethidium bromide. Southern blot analysis demonstrated that the 220-bp amplified fragment is specific for T. cruzi DNA and very useful to detect the presence of the parasite in blood from chronic chagasic patients.

Animals↗
PubMed1998

Characterization of the immunostimulatory properties of Leishmania infantum HSP70 by fusion to the Escherichia coli maltose-binding protein in normal and nu/nu BALB/c mice.

Leishmania infantum HSP70 has been described as an immunodominant antigen in both humans and dogs suffering from visceral leishmaniasis. In this study, we used L. infantum HSP70 fused to Escherichia coli maltose-binding protein (MBP), as the reporter protein, to analyze the influence of HSP70 on the immunogenicity of MBP in BALB/c mice. Plasmids were constructed to produce the three recombinant proteins used in this study, namely, MBP, L. infantum HSP70, and MBP-HSP70, which consists of MBP fused to the L. infantum HSP70 amino terminus. Immunization of BALB/c mice with the MBP-HSP70 fusion protein elicited humoral and cellular responses against MBP that were higher by an order of magnitude than those elicited by immunization with MBP alone or with a mixture of MBP and HSP70. Covalent linkage of MBP to HSP70 was essential for eliciting a strong anti-MBP immune response. Cytokine secretion and immunoglobulin G isotype analyses indicated that immunization with the MBP-HSP70 fusion protein preferentially induces a Th1 immune response. Immunization of athymic nu/nu mice with the MBP-HSP70 fusion protein unexpectedly gave rise to an anti-MBP humoral response showing features of a T-cell-dependent response. Thus, we present evidence that L. infantum HSP70 demonstrates an adjuvant effect in the immune response against a covalently linked reporter protein.

Animals↗
PubMed1998

Multicomponent chimeric antigen for serodiagnosis of canine visceral leishmaniasis.

In this work, we describe the assembly of a synthetic gene coding for several antigenic determinants found in different Leishmania infantum antigens. Selected epitopes were derived from the ribosomal proteins LiP2a, LiP2b, and LiP0 and from the histone H2A. The resulting gene was overexpressed in Escherichia coli either as a fusion protein (with the vector pMAL-c2) or alone (with the vector pQE). In both cases, high-level bacterial production of the recombinant protein was achieved and the products were found to be stable. Enzyme-linked immunosorbent assay (ELISA) and Western blotting experiments confirmed that the corresponding epitopes are present in the engineered protein. Finally, a serological evaluation of this multiple-epitope protein by Falcon assay screening test-ELISA revealed a sensitivity of 79 to 93% and a specificity of 96 to 100% in diagnosis of canine visceral leishmaniasis, indicating that this protein represents a valuable tool for serodiagnosis.

Amino Acid Sequence↗
PubMed1998

Functionality and cell anchorage dependence of the African swine fever virus gene A179L, a viral bcl-2 homolog, in insect cells.

The African swine fever virus gene A179L has been shown to be a functional member of the ced9/bcl-2 family of apoptosis inhibitors in mammalian cell lines. In this work we have expressed the A179L gene product (p21) under the control of the baculovirus polyhedrin promoter using a baculovirus system. Expression of the A179L gene neither altered the baculovirus replication phenotype nor delayed the shutoff of cellular protein synthesis, but it extended the survival of the infected insect cells to very late times postinfection. The increase in cell survival rates correlated with a marked apoptosis reduction after baculovirus infection. Interestingly, prevention of apoptosis was observed when recombinant baculovirus infections were carried out in monolayer cell cultures but not when cells were infected in suspension, suggesting a cell anchorage dependence for p21 function in insect cells. Cell survival was enhanced under optimal conditions of cell attachment and cell-to-cell contact as provided by extracellular matrix components or poly-D-lysine. Since it was observed that cytoskeleton organization varied depending on culture conditions of insect cells (grown in monolayer versus grown in suspension), these results suggested that A179L might regulate apoptosis in insect cells only when the cytoskeletal support of intracellular signaling is maintained upon cell adhesion. Thus, cell shape and cytoskeleton status might allow variations in intracellular transduction of signals related to cell survival in virus-infected cells.

African Swine Fever Virus↗
PubMed1997

Molecular cloning and analysis of expression of the Leishmania infantum histone H4 genes.

In the present work, we describe the sequence, organization and expression of histone H4 genes in the protozoan parasite Leishmania infantum. The predicted L. infantum histone H4 is a polypeptide of 100 amino acids with a molecular mass of 11.5 kDa. Comparison of the amino acid sequence of Leishmania histone H4 with the rest of histone H4 sequences indicates that this is the most divergent sequence reported to date. The genomic distribution analysis of histone H4 genes indicates that there must be up to seven gene copies. A single size-class histone H4 mRNA of 0.6 kb was detected, whose level dramatically decreases from logarithmic to stationary phase. However, the Leishmania histone H4 mRNAs do not decrease in abundance following treatment with inhibitors of DNA synthesis, suggesting a regulation by a replication-independent mechanism.

Amino Acid Sequence↗
PubMed1997

The open reading frame 1 of the L1Tc retrotransposon of Trypanosoma cruzi codes for a protein with apurinic-apyrimidinic nuclease activity.

The deduced amino acid sequence of the open reading frame 1 (ORF1) of the L1Tc non-site-specific non-long terminal repeat retrotransposon of Trypanosoma cruzi exhibits a significant homology with the consensus sequence of the class II family of the endonuclease apurinic-apyrimidinic (AP) proteins. The analysis of the activity of the 40-kDa recombinant protein, named NL1Tc, obtained from the expression of the L1Tc ORF1 in an Escherichia coli "in vitro" expression system revealed that the sequence codes for a protein with endonuclease activity specific for apurinic-apyrimidinic (AP) sites. Data are also presented showing that in vivo expression of the NL1Tc protein conferred viability by complementation to E. coli exonuclease III deletion mutants (BW286 strain). We propose that the biological function of the AP endonuclease activity of the NL1Tc protein may be connected with the introduction into the DNA of free 3' ends that could be used as primers for the integration, along the T. cruzi genome, of the L1Tc element and that the nicking could be a general mechanism for the retrotransposition of non-site-specific non-long terminal repeat retrotransposons.

Amino Acid Sequence↗
PubMed1997

Analysis of post-transcriptional regulation operating on transcription products of the tandemly linked Leishmania infantum hsp70 genes.

The genomic organization and expression of the hsp70 genes of Leishmania infantum were examined. In the cluster there are at least six copies of the hsp70 genes arranged in a head-to-tail tandem of 3. 8-kilobase repetition units. The hsp70 gene copy (gene 6) located at the 3' end of the tandem has a 3'-untranslated region highly divergent in sequence relative to the 3'-untranslated region of the rest of hsp70 gene copies (genes 1-5). Nuclease S1 protection assays indicated that the steady-state level of the mRNAs derived from gene 6 is about 50-fold more abundant than the transcript level derived from genes 1-5. Nuclear run-on assays showed, however, that all hsp70 genes are transcribed at similar rates. Thus, it is likely that the differences in the steady-state levels of the transcripts from the hsp70 genes should be associated with variations in their processing or maturation rates. While the abundance of the mRNAs derived from hsp70 genes 1-5 is increased by heat shock, the hsp70 gene 6 mRNA level remains unaffected. Our data showed that ongoing protein synthesis is required for the maintenance of the heat inducement, depicting, thus, a post-transcriptional mechanism of positive regulation involving a labile protein factor that would be either induced or activated during heat shock.

Animals↗
PubMed1997

Identification of a Trypanosoma cruzi antigenic epitope implicated in the infectivity of fibroblast LLC-MK2 cells.

In the present paper we describe the identification of an antigenic epitope that appears to be associated with the surface membrane of the Trypanosoma cruzi parasite, probably implicated in infectivity. Anti-TcMe antibodies inhibited the infectivity of fibroblast LLC-MK2 cells by 34% relative to a preimmune serum. The epitope was specifically recognized by 55% of the sera from 80 chagasic patients. The anti-TcMe antibody immunoprecipitated proteins of about 60 and 40 kDa from epimastigote and cell-culture trypomastigote forms, respectively. It is likely that the 60- and 40-kDa proteins are processed from higher-molecular-weight precursors, since the antibody immunoprecipitated protein fractions in the range of 115-150 kDa from in vitro translation products of poly A+ RNA.

Amino Acid Sequence↗
PubMed1997

Reverse transcriptase-like activity in Trypanosoma cruzi.

The use of specific synthetic RNA homopolymers as templates and short oligonucleotides as primers has allowed evidence of the existence of a reverse transcriptase-like activity in Trypanosoma cruzi, to be revealed. The RNA:DNA products derived from this reaction are of approximately 110 nucleotides in length. The enzyme has greater affinity for poly(rA)/ oligo(dT) templates than for poly(rC)/oligo(dG) having a 20 mM Mg+2 ion requirement. The detected reverse transcriptase-like activity is not affected by aphidicolin and ddTTP but is inhibited by actinomycin D. novobiocin, rifamycin SV and AZT.

Animals↗