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Biomedical subjects

C Alonso

Publications and source records attributed to C Alonso.

At least 127 records · Page 7Linked to original sources
PubMed1999

Macrophage tropism of rabbit hemorrhagic disease virus is associated with vascular pathology.

To delineate the interactions between rabbit hemorrhagic disease virus (RHDV) and host cells, organ and cellular targets of infection were identified in vivo. Viral specific antigens were detected by immunohistochemistry in liver, lung, spleen and lymph nodes cells. Also, intravascular infected cells were detected in most organs including kidneys, myocardium, thymus and central nervous system. To further characterize infected target cells, viral proteins and cell-specific surface antigens were identified simultaneously in double labeling experiments. Numerous lymphoid organ macrophages, from the splenic red pulp, circulating monocytes, alveolar macrophages and Kupffer cells were double labeled, demonstrating that cells of the mononuclear phagocyte lineage are major hosts for RHDV. Double labeling for other specific cell markers were negative. The distribution of viral antigens in these tissues coincided with those areas where cells presented morphology of apoptosis. Association of intravascular monocyte infection and apoptosis, could represent a possible mechanism to develop disseminated intravascular coagulation.

Animals↗
PubMed1999

Antigenicity of the Leishmania infantum histones H2B and H4 during canine viscerocutaneous leishmaniasis.

In this study we show that sera from dogs naturally infected with Leishmania infantum contain antibodies that specifically react against the parasite H2B and H4 histones. The Leishmania H2B and the amino-terminal region of the histone H4, expressed as fusion proteins, when confronted with sera from canine viscerocutaneous leishmaniasis (VCL) dogs, were recognized by 63% and 47%, respectively. No reactivity was detected when sera from dogs naturally infected with pathogens other than Leishmania were used. Using a collection of synthetic peptides covering the complete sequence of both proteins, we have determined that the main linear antigenic determinants are located in the amino-terminal domains of these histones. The humoral response against histones H2B and H4 induced during canine leishmaniasis was found to be specific for Leishmania histones, since no cross-reactivity of the VCL sera with mammal histones was observed. Also, a comparative study of the prevalence of antibodies among VCL sera against the four core histones of L. infantum was performed. Although a large heterogeneity of the humoral responses against these proteins was found, histones H2A and H3 seem to be more prevalent immunogens than histones H2B and H4 during canine natural leishmaniasis. The origin of the anti-histone humoral response and its possible implications in the pathogenesis of Leishmania infection are discussed.

Amino Acid Sequence↗
PubMed1999

Folding stability of the kinetoplastid membrane protein-11 (KMP-11) from Leishmania infantum.

Kinetoplastid membrane protein-11 (KMP-11) is a major component of the cell surface of kinetoplastids, and acts as a potent B- and T-cell immunogen during Leishmania infection. Here we report that the Leishmania infantum KMP-11 secondary structure adopts mainly an alpha-helical conformation at pH 7.5 and that its urea- and thermally-induced unfolding constitute a fully reversible two-step process. This allows estimation of a half-denaturation temperature of approximately 65 degrees C, a delta GDH2O at 20 degrees C of approximately 14.63 kJ.mol-1, and an increment of the reaction heat of approximately 183.92 kJ.mol-1 and an entropy of approximately 543.4 J.mol-1.deg-1, respectively, for the native-denatured equilibrium of the KMP-11 in solution. We also report that the KPM-11 protein is induced to adopt a molten globule state at a pH range between pH 4 and pH 6. As a whole, the stability and the specific features of the denaturing effect induced by changes in pH are similar in KMP-11 to various other lipoproteins.

Amino Acid Sequence↗
PubMed1999

Small-cell lung cancer in the elderly--is age of patient a relevant factor?

Different management procedures for diagnosis and treatment of small-cell lung cancer (SCLC) and other tumours in the elderly have been reported, but there is a lack of data from a communal hospital perspective. Information on clinical parameters such as weight loss, co-morbidity, performance status and investigative procedures for staging of disease and inclusion in clinical trials was recorded for patients in the province of Albacete (Spain). Patients' ages were categorized in two groups: under 70 years and 70 years or more, and a comparison of treatment variables, toxicities, response and time to event measures was carried out. Ninety-five patients were referred to our Unit for treatment. Of these patients, 62% were under 70 years of age and 38% were in the older age category. Clinical variables and staging procedures did not differ between groups. Trial assignment showed a bias in favour of younger patients (11 vs. 1, p = 0.02). No differences in the number of patients without treatment were found, but the older group presented fewer cases of optimal (> or = 4 cycles) therapy, less chemotherapy delivery (smaller mean total doses of cisplatin and etoposide) and smaller mean total dose of radiotherapy (57/45 Gy). The response to treatment (46%/50%) toxicity registered and overall survival did not differ between age categories. Age does not seem to be a relevant prognostic factor in this disease. Carefully calculated dose reductions for chemotherapy in elderly patients based on initial performance status and/or toxicity during treatment may be a useful policy without detrimental implications on outcome.

Age Factors↗
PubMed1999

African swine fever virus infection induces tumor necrosis factor alpha production: implications in pathogenesis.

We have analyzed the production of tumor necrosis factor alpha (TNF-alpha) induced by in vitro infection with African swine fever (ASF) virus (ASFV) and the systemic and local release of this inflammatory cytokine upon in vivo infection. An early increase in TNF-alpha mRNA expression was detected in ASFV-infected alveolar macrophages, and high levels of TNF-alpha protein were detected by ELISA in culture supernatants from these cells. When animals were experimentally infected with a virulent isolate (E-75), enhanced TNF-alpha expression in mainly affected organs correlated with viral protein expression. Finally, elevated levels of TNF-alpha were detected in serum, corresponding to the onset of clinical signs. TNF-alpha has been reported to be critically involved in the pathogenesis of major clinical events in ASF, such as intravascular coagulation, tissue injury, apoptosis, and shock. In the present study, TNF-alpha containing supernatants from ASFV-infected cultures induced apoptosis in uninfected lymphocytes; this effect was partially abrogated by preincubation with an anti-TNF-alpha specific antibody. These results suggest a relevant role for TNF-alpha in the pathogenesis of ASF.

African Swine Fever↗
PubMed1999

The mother's participation in infant carrying in captive groups of Leontopithecus chrysomelas and Callithrix jacchus.

Callithrix and Leontopithecus exhibit ecological differences that have implications for the patterns of infant care. In C. jacchus, which uses a small home range because it depends mainly on plant exudates, infants can forage independently early in their life. L. chrysomelas, which feeds mainly on fruits and insects, needs larger home ranges and, therefore, its infants have a more extensive period of dependence. Three families of C. jacchus and four families of L. chrysomelas were studied in captivity. The animals were observed starting from the birth of the infants up to their 8th week of age. Our results suggest that the pattern of infant transfer in L. chrysomelas did not follow the one reported for L. rosalia in that transfers from the mother occurred much earlier. L. chrysomelas infants were carried for about 15% of total time during the 8th week of life against less than 1% in C. jacchus in the same week. Infant care seems to be more extensive in L. chrysomelas than in C. jacchus, and the period of exclusive mother carrying in L. chrysomelas is shorter than that observed in L. rosalia.

Animals↗
PubMed1999

The formation of DNA interstrand cross-links by a novel bis-[Pt2Cl4(diminazene aceturate)2]Cl4.4H2O complex inhibits the B to Z transition.

We present data demonstrating that the cytotoxic compound [Pt2Cl4(diminazene aceturate)2]Cl4.4H2O (Pt-berenil) circumvents cisplatin resistance in ovarian carcinoma cells. The analysis of the interaction of Pt-berenil with linear and supercoiled DNA indicates that this compound induces the formation of a large number of covalent interstrand cross-links on DNA and that this number is significantly higher than that produced by cis-diamminedichloroplatinum(II) (cis-DDP). Renaturation experiments, interstrand cross-link assays, and electron microscopy indicate that the kinetics of DNA interstrand cross-link formation caused by Pt-berenil binding is faster than that caused by cis-DDP at similar levels of platinum bound to DNA. Furthermore, the number of DNA interstrand cross-links in Pt-berenil-DNA complexes is influenced by supercoiling. Circular dichroism experiments show that Pt-berenil strongly inhibits the B-DNA-to-Z-DNA transition of poly(dG-m5 dC). poly(dG-m5dC) at salt concentrations (3 mM MgCl2) at which the native methylated polynucleotide readily adopts the Z-DNA conformation, which suggests that the induction of interstrand cross-links by Pt-berenil inhibits the Z-DNA transition. On the basis of these results, we propose that bis(platinum) compounds with structure similar to Pt-berenil may act as blockers of DNA conformational changes and may also display activity in cisplatin-resistant cells.

Animals↗
PubMed1999

[Brain natriuretic peptide (BNP) in coronary insufficiency: relationship with left ventricular filling and exercise tolerance].

Brain natriuretic peptide (BNP) is a recently discovered peptide, secreted by the atria and ventricles in response to parietal distension. It was recently proposed as a screening test for left ventricular failure. The authors assayed this peptide at rest in 37 patients with chronic heart failure due to left ventricular systolic dysfunction and another 20 patients with various diseases (respiratory failure, cirrhosis, heart transplantation, "diastolic" heart failure) but normal left ventricular systolic function. A significant increase compared to normal values was observed not only in the group of heart failure patients, but also in patients with all other diseases. BNP was significantly higher in NYHA class IV patients. The relationship between plasma BNP levels and ejection fraction was not significant. On the other hand, a good correlation was observed between BNP and left ventricular filling parameters evaluated by cardiac Doppler: E wave deceleration time (r = -0.53, p = 0.001), E/A ratio: r = 0.57 p = 0.005) or VO2 max (r = -0.55, p < 0.005).

Aged↗
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↗