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Biomedical subjects

Antonio Rojas

Publications and source records attributed to Antonio Rojas.

6 recordsLinked to original sources
PubMed2006

2-Acetyl-1,3-cyclopentanedione-oxovanadium(IV) complexes. Acidity and implications for gastrointestinal absorption.

Since vanadyl sulphate has demonstrated insulin-like effects on glucose metabolism in animal and human trials, and organic vanadium complexes are better absorbed by the intestinal tract than vanadyl species, in this work the complexation of oxovanadium(IV) with 2-acetyl-1,3-cyclopentanedione is studied. Kinetic and equilibria in aqueous 1:1 chelation are investigated spectrophotometrically in aqueous solution at 25 degrees C. The mechanism proposed to account for the kinetic data involves a reversible pathway where VO(+2) reacts with the enolate ion of the ligand. From calculated kinetic and thermodynamic parameters, it can be expected that the rates between final and initial monocharged complex concentration could help a better control of the absorption through the lipophilic membranes in the intestinal tract.

Animals↗
PubMed2004

Use of polymerase chain reaction (PCR) and hybridization assays to detect Trypanosoma cruzi in chronic chagasic patients treated with itraconazole or allopurinol.

The presence of Trypanosoma cruzi in chronic chagasic patients with negative xenodiagnosis (XD) after 6 years following completion of therapy with either itraconazole or allopurinol was assessed by polymerase chain reaction (PCR) and hybridization assays. A 330-bp DNA fragment amplified from the hypervariable regions of T. cruzi kinetoplastid minicircles was hybridized with total 32P-labeled kinetoplast DNA as probes. PCR alone enabled the identification of T. cruzi nucleotide sequences in 40% of the patients treated with itraconazole and in 60% of patients treated with allopurinol. PCR used in combination with hybridization detected parasite DNA in 60% and 53% of XD negative individuals treated with itraconazole or allopurinol, respectively. These results show that PCR and hybridization are more sensitive than conventional parasitological techniques in diagnosing patients that have undergone chemotherapy with itraconazole or allopurinol.

Adult↗
PubMed2004

Reduced genetic structure of the Iberian peninsula revealed by Y-chromosome analysis: implications for population demography.

Europe has been influenced by both intra- and intercontinental migrations. Since the Iberian peninsula was a refuge during the Last Glacial Maximum, demographic factors associated with contraction, isolation, subsequent expansion and gene flow episodes have contributed complexity to its population history. In this work, we analysed 26 Y-chromosome biallelic markers in 568 chromosomes from 11 different Iberian population groups and compared them to published data on the Basques and Catalans to gain insight into the paternal gene pool of these populations and find out to what extent major demographic processes account for their genetic structure. Our results reveal a reduced, although geographically correlated, Y-chromosomal interpopulation variance (1.2%), which points to a limited heterogeneity in the region. Coincidentally, spatial analysis of genetic distances points to a focal distribution of Y-chromosome haplogroups in this area. These results indicate that neither old or recent Levantine expansions nor North African contacts have influenced the current Iberian Y-chromosome diversity so that geographical patterns can be identified.

Chromosomes, Human, Y↗
PubMed2003

Frameshift mutation events in beta-glucosidases.

Compensated frameshift mutation is a modification of the reading frame of a gene that takes place by way of various molecular events. It appears to be a widespread event that is only observed when homologous amino acid and nucleodotide sequences are compared. To identify these mutation events, the sequence analysis rationale was based on the search for short regions that would have much lower degrees of conservation in protein, but not in DNA, in well-conserved beta-glucosidase families. We have restricted our study to a seed set of sequences of O-glycoside hydrolase families 1 and 3. We found compensated frameshift mutation in the family of 1 beta-glucosidases for the Erwinia herbicola, Cellulomonas fimi, and (non-cyanogenic) Trifolium repens gene sequences, and in the family of 3 beta-glucosidases for the Clostridium thermocellum and Clostridium stercorarium gene sequences. By computational treatment, the observed mutation events in the gene frameshifting sub-sequence have been neutralised. Each nucleotide insertion must be eliminated and each nucleotide deletion must be substituted by the symbol N (any nucleotide). When the frameshifting fragments of the amino acid sequences were substituted by the computationally neutralised subsequences, the beta-glucosidase alignments were improved. We also discuss the structural implications of the compensated frameshift mutations events.

Amino Acid Sequence↗
PubMed2002

[Malaria in Chile: 1913-2001].

BACKGROUND: Malaria was restricted to the I Region of Chile, being Anopheles pseudopunctipennis the only vector species. In 1936 the parasitosis affected more than 50% of the population and 62.4% of military recruits, proceeding from Southern regions became infected. From 1937 to 1947, an antimalaria campaign was carried out, stressing actions on the battle against the vector and the treatment of malaria infected individuals. Since April 1945 no autochthonous cases of malaria have been detected. AIM: To update the situation of malaria in Chile. METHODS: 1) Imported malaria: Analysis of occasional publications on the subject (1945-1988) and the annual reports of the Ministry of Health Department of Epidemiology (1990-2001). Annual reports on the Anopheles specimens collected--mostly larvae--in the provinces of Arica and Iquique and examined in the Parasitology Unit of the School of Medicine, University of Chile, during the period 1980-2001. RESULTS: 1) Imported malaria. A total of 24 cases were published in the period 1945-1988. In the 1980-2001 period, the Ministry of Health recorded 66 cases with 5 (8.8%) deaths. 2) Anophelines: Only in 1984, 1985, 1998 and 2001 A. pseudopunctipennis foci were detected. Entomological surveillance was stressed and insecticides were applied on these focuses. CONCLUSIONS: Autochthonous malaria does not exist in Chile since 1945. The detection of malaria cases in countries where the parasitosis was eradicated, can be the result of tourism or migrations. In Chile, the Environmental Programs of Arica and Iquique perform periodical surveys in localities where mosquitoes exist. When A. pseudopunctipennis is found, the entomological vigilance is stressed and insecticide applications are reiterated until the situation is controlled.

Animals↗