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C Alonso

Publications and source records attributed to C Alonso.

At least 37 records · Page 2Linked to original sources
PubMed1998

The expression of the Leishmania infantum KMP-11 protein is developmentally regulated and stage specific.

Transcription of the gene coding for the KMP-11 protein of Leishmania infantum results in the production of a mature RNA transcript of 1.3 kb in length. The expression of KMP-11 mRNA is strongly down-regulated not only during the parasite growth from the logarithmic to the stationary phase but also during the differentiation transit from promastigotes to amastigotes. The estimated concentration of KMP-11 is one order of magnitude higher in promastigotes than in amastigotes. The analysis of the Triton X-114 phase partition of the protein shows that, in agreement with its predicted secondary structure, KMP-11 has an amphipathic nature since it is found in the aqueous as well as in the detergent phase. By fluorescence microscopy a defined pattern of distribution of the protein was observed only in promastigotes where KMP-11 is mainly located in the flagellum and the flagellar pocket.

Animals↗
PubMed1998

3-Hydroxy-3-methylglutaryl coenzyme a reductase and isoprenylation inhibitors induce apoptosis of vascular smooth muscle cells in culture.

Recent evidence suggests that apoptosis may be involved in the control of vascular smooth muscle cell (VSMC) number in atherosclerotic lesions. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been reported to induce apoptosis in a variety of tumor cell lines. To evaluate whether these agents also induce apoptosis of VSMCs, cultured rat VSMCs were treated with increasing doses of atorvastatin in the presence of FBS as a survival factor. The presence of apoptosis was evaluated by morphological criteria, annexin V binding, and DNA fragmentation and quantified as the proportion of hypodiploid cells by flow cytometry. Atorvastatin induced apoptosis in a dose-dependent manner, an effect also seen with simvastatin and lovastatin, but not with the hydrophilic drug pravastatin. The proapoptotic effect of statins was seen only when the inhibition of acetate incorporation into sterols was >95% and was fully reversed by mevalonate, farnesyl pyrophosphate, and geranylgeranyl pyrophosphate but not by isopentenyl adenosine, ubiquinone, or squalene, suggesting a role for prenylated proteins in the regulation of VSMC apoptosis. To further assess the role of protein prenylation, VSMCs were exposed to the prenyl transferase inhibitors perillic acid and manumycin A. Both agents induced VSMC apoptosis as evaluated by the above-mentioned criteria. Finally, VSMC treatment with lipophilic statins was associated with decreased prenylation of p21-Rho B, further supporting the role of protein prenylation inhibition in statin-induced VSMC apoptosis. The present data suggest that interference with protein prenylation by HMG-CoA reductase inhibitors or other agents may provide new strategies for the prevention of neointimal thickening.

Animals↗
PubMed1998

Control mechanisms of the H2A genes expression in Trypanosoma cruzi.

In a previous report we have described that the T. cruzi histone H2A gene is encoded in two independent gene clusters located in a single chromosome. In the present paper we show that both gene cluster are actively transcribed as two sized classes of polyadenylated mRNAs demonstrating, moreover, the existence of alternative splicing sites and microheterogeneities at the polyadenylation site. We also describe that while the expression of the H2A genes in the non replicative trypomastigote forms is only residual, in the replicative forms there is constitutive transcription of these genes and that the transcription is not associated to DNA replication. The data show, moreover, that in the replicative forms the steady state levels of the H2A mRNAs are controlled at a post-transcriptional level which is associated to DNA replication.

Amino Acid Sequence↗
PubMed1998

Novel tetranuclear orthometalated complexes of Pd(II) and Pt(II) derived from p-isopropylbenzaldehyde thiosemicarbazone with cytotoxic activity in cis-DDP resistant tumor cell lines. Interaction of these complexes with DNA.

The reaction of p-isopropylbenzaldehyde thiosemicarbazone [p-is.TSCN], 1, with palladium(II) acetate and potassium tetrachloroplatinate yielded two tetrameric orthopalladated isomers, [Pd(p-is.TSCN)]4 (complexes 2 and 3), and the platinum analogue [Pt(p-is.TSCN)]4 (complex 4), respectively. All of these complexes contain the thiosemicarbazone bonded as a terdentate ligand to the metallic atom, through the thiol sulfur, the azomethinic nitrogen and the ortho carbon of the p-isopropylphenyl ring to which the imine group is attached to as deduced from the study of the IR, NMR, and XRD spectra of complexes 2 and 4. Complexes 2 and 4 crystallize in the centrosymmetric monoclinic space group C2/c, with Z = 8. Unit cell parameters for complex 2 are as follows: a = 25.742(5) A, b = 19.560(4) A, c = 24.199(5) A, beta = 101.70(3)o. Unit cell parameters for complex 4 are as follows: a = 25.8728(19) A, b = 19. 5053(14) A, c = 24.0899(16) A, beta = 101.305(2)o. As can be deduced from the NMR study, the palladated isomers 2 and 3 interconvert in DMSO which may be a consequence of the existence in both complexes of a flexible eight-membered ring with alternating Pd-S atoms. The testing of the cytotoxic activity of these compounds against several human and murine cell lines sensitive and resistant to cisplatin (cis-DDP) suggests that compounds 2, 3, and 4 may be endowed with important anticancer properties since they elicit IC50 values in the microM range as does the clinically used drug cis-DDP, and, moreover, they display cytotoxic activity in tumor lines resistant to cis-DDP. The analysis of the interaction of these novel tetrameric cyclometalated compounds with DNA suggests that they form DNA interhelical cross-links.

Animals↗
PubMed1998

The African swine fever virus proteins p54 and p30 are involved in two distinct steps of virus attachment and both contribute to the antibody-mediated protective immune response.

The nature of the initial interactions of African swine fever (ASF) virus with target cells is only partially known, and to date only the ASF virus protein p12 has been identified as a viral attachment protein. More recently, antibodies to viral proteins p54 and p30 have been shown to neutralize the virus, inhibiting virus binding and internalization, respectively. Therefore, we investigated the role of these proteins in the receptor-mediated ASF virus endocytosis in swine macrophages, the natural host cells. Proteins p54 and p30, released from ASF virus particles after treatment of virions with a nonionic detergent, bound to virus-sensitive alveolar pig macrophages. Binding of these proteins was found to be specifically inhibited by neutralizing antibodies obtained from a convalescent pig or from pigs immunized with recombinant p54 or p30 proteins. The baculovirus-expressed proteins p54 and p30 retained the same biological properties as the viral proteins, since they also bound specifically to these cells, and their binding was equally inhibited by neutralizing antibodies. Binding of 35S-labeled recombinant p54 and p30 proteins to macrophages was specifically competed by an excess of unlabeled p54 and p30, respectively. However, cross-binding inhibition was not observed, suggesting the existence of two different saturable binding sites for these proteins in the susceptible cells. In addition, protein p54 blocked the specific binding of virus particles to the macrophage, while protein p30 blocked virus internalization. Both proteins independently prevented virus infection and in a dose-dependent manner, suggesting that binding interactions mediated by both proteins are necessary to give rise to a productive infection. The relevance of blockade of virus-cell interactions mediated by p54 and p30 in the protective immune response against ASF virus was then investigated. Immunization of pigs with either recombinant p54 or p30 proteins induced neutralizing antibodies which, as expected, inhibited virus attachment or internalization, respectively. However, immunized pigs were not protected against lethal infection and the disease course was not modified in these animals. In contrast, immunization with a combination of p54 and p30 proteins simultaneously stimulated both virus neutralizing mechanisms and modified drastically the disease course, rendering a variable degree of protection ranging from a delay in the onset of the disease to complete protection against virus infection. In conclusion, the above results strongly suggest that proteins p54 and p30 mediate specific interactions between ASF virus and cellular receptors and that simultaneous interference with these two interactions has a complementary effect in antibody-mediated protection.

African Swine Fever↗
PubMed1998

[Invasive pulmonary aspergillosis: a study of 33 cases].

Invasive pulmonary aspergillosis (IPA) is an infectious complication appearing mainly in immunosuppressed patients, whose diagnosis is often difficult and lately made, and that usually bears a dismal prognosis. Patients diagnosed as having IPA from 1989 to 1994 were retrospectively analyzed. Probable IPA was diagnosed on the basis of a positive culture for Aspergillus together with a consistent radiological image. Confirmed IPA was diagnosed if there was, in addition to the former, a pathological examination showing Aspergillus hifae invading pulmonary parenchyma and/or pulmonary vessels. There were 25 men and 8 women with a mean age of 53.7 +/- 16.9 years (range: 22-86 years). IPA was confirmed in 11 cases and probable in 22. Sixty three percent of the patients had hematologic malignancy or solid cancer, whereas 30.3% did not have prior granulocytopenia or immunosuppressive therapy. The mean (SD) interval between admission and diagnosis was 40.2 (37.1) days (range: 1-180 days), and the diagnosis was made while the patient was still alive in 75% of the cases. Fifteen percent of the patients had extrapulmonary aspergillosis. The most frequent finding both on X-ray film of the chest and pulmonary computed tomography were bilateral multiple pulmonary nodules. Thirteen patients were treated with itraconazole, 6 with amphotericin B, 5 received both drugs, and 2 received fluconazole. Nineteen patients (57.6%) died and the case-fatality rate among treated patients was 46.1%. IPA presents mainly in immunosuppressed patients, but there was a not negligible proportion of patients lacking the classical risk factors. IPA is often a lately made diagnosis and in a quarter of the patients it is not made when the patient is alive. The most frequent radiological presentation are multiple bilateral nodules. The case-fatality rate of IPA is exceedingly high, even when if the patient has been adequately treated.

Adult↗
PubMed1998

Molecular analysis of the six most recurrent mutations in the BRCA1 gene in 87 Spanish breast/ovarian cancer families.

BRCA1 accounts for nearly all families with multiple cases of both early onset breast and ovarian cancer and about 45% of families with breast cancer only. Although to date more than 200 distinct mutations have been described, several have been found to be recurrent in the gene. We have analyzed 87 Spanish breast/ovarian cancer families for the six most recurrent mutations in the BRCA1 gene. The analysis of the five exons where these mutations are located was made using the SSCP and sequenciation techniques. Four mutations were found in our families and only two carried one of the six mutations analyzed. In both cases the mutation identified was 185delAG. Our results suggest that these six mutations are not specially recurrent in the Spanish population and that differences in the geographical origin of the families can influence the type and proportion of mutations identified.

Adult↗
PubMed1998

Cloning, sequencing, and expression of the PSA genes from Leishmania infantum.

We describe the molecular cloning of the PSA genes from the Leishmania infantum parasite, which show high sequence similarity with the L. major PSA-2 and L. amazonensis GP46/M2 genes. The PSA genes in L. infantum are arrayed in tandem with a repetition unit of 6 kb. A single-size class of PSA mRNA of 4 kb was detected. The characterised L. infantum PSA genes code for a protein lacking the glycosylphosphatidylinositol addition signal described in other Leishmania species due to the presence of a stop codon located upstream from the DNA sequence coding for the signal. The data obtained after immunoprecipitation of PSA indicate that the protein is present as a water-soluble form, but that also a membrane-anchored form can be detected. The amino acid sequence derived from the isolated PSA gene shows that 60% of the deduced protein is formed by 13 leucine-rich repeats, each one of which is 24 amino acids long. The analysis of the consensus sequence of the repeats revealed that the L. infantum PSA as well as the described L. major PSA-2 and L. amazonensis GP46/M2 proteins may be classified as new members of the leucine-rich repeat-containing protein superfamily. The number of leucine-rich motifs, however, varies considerably between the PSA protein from L. infantum and from the other Leishmania species. The PSA protein is a major antigen determinant during L. infantum infections since 87% of the sera from naturally infected dogs recognise the recombinant PSA purified from Escherichia coli.

Amino Acid Sequence↗
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↗