Biomedical subjects

A I González

Publications and source records attributed to A I González.

11 recordsLinked to original sources

PubMed2001

Acidity trends in alpha,beta-unsaturated alkanes, silanes, germanes, and stannanes.

The gas-phase acidity of ethyl-, vinyl-, ethynyl-, and phenyl-substituted silanes, germanes, and stannanes has been measured by means of FT-ICR techniques. The effect of unsaturation on the intrinsic acidity of these compounds and the corresponding hydrocarbons was analyzed through the use of G2 ab initio and DFT calculations. In this way, it was possible to get a general picture of the acidity trends within group 14. As expected, the acid strength increases down the group, although the acidity differences between germanium and tin derivatives are already rather small. As has been found before for amines, phosphines, and arsines, the carbon, silicon, germanium, and tin alpha,beta-unsaturated compounds are stronger acids( )than their saturated analogues. The acidifying effect of unsaturation is much larger for carbon than for Si-, Ge-, and Sn-containing compounds. The allyl anion is better stabilized by resonance than its Si, Ge, and Sn analogues, [CH(2)(-)(delta)--CH(+)(delta)(') --CH(2)(-)(delta)](-) vs [CH(2)(-)(delta)()II = CH(-)(delta)()III - XH(2)(-)(delta)()IV](-) (X = Si, Ge, Sn). The enhanced acid strength of unsaturated compounds is essentially due to a greater stabilization of the anion with respect to the neutral, because the electronegativity of the alpha,beta-unsaturated carbon group increases with its degree of unsaturation. The phenyl derivatives are systematically weaker acids than the corresponding ethynyl derivatives by 15-20 kJ mol(-)(1). Experimentally, toluene acidity is very close to that of propyne, because the deprotonation of propyne takes place preferentially at the =CH group rather than at the -CH(3) group.

Journal Article↗

PubMed2000

Patterns of variation in the intergenic spacers of ribosomal DNA in Drosophila melanogaster support a model for genetic exchanges during X-Y pairing.

Detailed analysis of variation in intergenic spacer (IGS) and internal transcribed spacer (ITS) regions of rDNA drawn from natural populations of Drosophila melanogaster has revealed contrasting patterns of homogenization although both spacers are located in the same rDNA unit. On the basis of the role of IGS regions in X-Y chromosome pairing, we proposed a mechanism of single-strand exchanges at the IGS regions, which can explain the different evolutionary trajectories followed by the IGS and the ITS regions. Here, we provide data from the chromosomal distribution of selected IGS length variants, as well as the detailed internal structure of a large number of IGS regions obtained from specific X and Y chromosomes. The variability found in the different internal subrepeat regions of IGS regions isolated from X and Y chromosomes supports the proposed mechanism of genetic exchanges and suggests that only the "240" subrepeats are involved. The presence of a putative site for topoisomerase I at the 5' end of the 18S rRNA gene would allow for the exchange between X and Y chromosomes of some 240 subrepeats, the promoter, and the ETS region, leaving the rest of the rDNA unit to evolve along separate chromosomal lineages. The phenomenon of localized units (modules) of homogenization has implications for multigene family evolution in general.

Animals↗

PubMed1998

Multigene family of ribosomal DNA in Drosophila melanogaster reveals contrasting patterns of homogenization for IGS and ITS spacer regions. A possible mechanism to resolve this paradox.

The multigene family of rDNA in Drosophila reveals high levels of within-species homogeneity and between-species diversity. This pattern of mutation distribution is known as concerted evolution and is considered to be due to a variety of genomic mechanisms of turnover (e.g., unequal crossing over and gene conversion) that underpin the process of molecular drive. The dynamics of spread of mutant repeats through a gene family, and ultimately through a sexual population, depends on the differences in rates of turnover within and between chromosomes. Our extensive molecular analysis of the intergenic spacer (IGS) and internal transcribed spacer (ITS) spacer regions within repetitive rDNA units, drawn from the same individuals in 10 natural populations of Drosophila melanogaster collected along a latitudinal cline on the east coast of Australia, indicates a relatively fast rate of X-Y and X-X interchromosomal exchanges of IGS length variants in agreement with a multilineage model of homogenization. In contrast, an X chromosome-restricted 24-bp deletion in the ITS spacers is indicative of the absence of X-Y chromosome exchanges for this region that is part of the same repetitive rDNA units. Hence, a single lineage model of homogenization, coupled to drift and/or selection, seems to be responsible for ITS concerted evolution. A single-stranded exchange mechanism is proposed to resolve this paradox, based on the role of the IGS region in meiotic pairing between X and Y chromosomes in D. melanogaster.

Animals↗

PubMed1998

A race-specific insertion of transposable element IS801 in Pseudomonas syringae pv. phaseolicola.

The isolation and cloning of a random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) band specific for Pseudomonas syringae pv. phaseolicola race 1 allowed us to design a pair of primers that amplify 1.2-kb race 1-specific and 2.7-kb race 2-specific fragments, providing a rapid method for the identification of races by standard PCR methods. Restriction analysis revealed identical endonuclease sites in both fragments but the race 2 fragment contains a 1.5-kb insertion, identified as transposable element IS801 by sequence comparison. One complete and one partial open reading frame (ORF), each with a high probability of encoding a protein, have been identified in the 1.2-kb fragment common to both race 1 and race 2 sequences. As IS801 disrupts the partial ORF in the race 2 fragment, the complete sequence of this ORF has been obtained as well as its promoter region. The possibility that it may encode an avirulence gene is discussed as well as the role of transposable elements in pathogen evolution.

Base Sequence↗

PubMed1997

Molecular characterization of a new human minisatellite that is able to form single-stranded loops in vitro and is recognized by nuclear proteins.

We report the isolation of a new low polymorphic GC-rich human minisatellite locus (MsH42) that contains different recombination motifs and is homologous to sequences involved in immunoglobulin class-switching. Furthermore, we show that MsH42 undergoes slipped-strand mispairing during PCR indicating its ability to generate single-stranded loops. Specific DNA-protein complexes were detected in band-shifting experiments using nuclear extracts from mouse testes and human NC-37 cells. The possible implications of this minisatellite in recombination events is discussed.

Animals↗

PubMed1997

[Cutaneous infections by Mycobacterium marinum. Description of 3 cases and review of the literature].

BACKGROUND: Human infection by Mycobacterium marinum is infrequent and is currently reported in association with the management of aquariums. The epidemiologic, clinical and microbiologic characteristics of three cases in our hospital are herein reported. METHODS: Three cases of cutaneous infection by M. marinum attended in our hospital from February 1993 to October 1994 are described. RESULTS: The three patients were related with the management of aquariums. In two cases the clinical presentation was of sporotricoid cutaneous dissemination, while the third patient presented a localized cutaneous form. The lesions were localized in the upper right extremity in the three cases. The delay in diagnosis was important in two of the cases. Cure, or improvement, were achieved in three cases with' treatment; one with cotrimoxazol, another with first line tuberculostatic drugs and another did not receive treatment. CONCLUSIONS: Human infection by M. marinum is currently described is association with the management of aquariums. The infection is usually cutaneous, alone or well disseminated, with invasion of deep tissue occasionally observed. The lesions are generally found on the upper extremities. Diagnostic delay is frequent. The most adequate treatment appears to be the combination of rifampicin plus etambutol or cotrimoxazol alone, with cases of spontaneous remission also being observed.

Adult↗

PubMed1996

[Epidemiology of gastroenteritis by Salmonella (1983-1994)].

BACKGROUND: The incidence of Salmonella enteritidis infection has been study in order to determine their epidemic spread from 1983 to 1994, and the impact of the measures introduced to attempt its control. METHOD: Review of the stool cultures positives for enteric pathogens obtained in the Hospital de Navarra from 1983-1994. RESULTS: Looking at the isolation rates of the different enteric pathogens from 1983 to 1994, a sharp increase of S. enteritidis was recorded on 1985 as a consequence of several outbreaks associated with the consumption of mayonnaise elaborated with row eggs. From 409 strains of Salmonella isolated that year, 302 were serotype enteritidis, this means a 7.5 fold rise since the preceding year in which the prevailing serotype was S typhimurium. From 1985 through 1991 the incidence of S. enteritidis stand high, and pick again on 1990. Since then, a decline has been observed, and in 1994 the number of Salmonella cases recorded were about those on 1984, however, S. enteritidis is now the prevailing serotype. CONCLUSIONS: The egg-borne S. enteritidis epidemic emerged as a major public health problem in Navarra in 1995, associated to the consumption of home made mayonnaise. The measures introduced by local Public Health authorities to attempt control of non pasteurized mayonnaise were insufficient. Evidence from other places links human infections to vertical transmission from breeding flocks to layers. And makes of S. enteritidis infection an international challenge. The severity of the lived experience demands a time-temperature control of eggs in the interval from purchaser to consumer and a more generalized use of pasteurized egg products, no only in the industry but also in the household.

Disease Outbreaks↗

PubMed1993

Detection of antibodies to Candida albicans germ tube as a possible aid in diagnosing systemic candidiasis in bone marrow transplant patients.

Indirect immunofluorescence assays to detect antibodies to Candida albicans blastospore and germ tube were performed in sera of 29 bone marrow transplant patients. Antibodies to germ tube were present in the sera of six patients, in four of whom a Candida albicans infection was highly probable, while in the other two patients it was not possible to determine the previous course. No healthy blood donors had these antibodies. On the other hand, detection of antibodies to Candida albicans blastospore showed low specificity in the diagnosis of systemic candidiasis. These preliminary findings suggest that the detection of antibodies to Candida albicans germ tube may be an important aid in the diagnosis of systemic candidiasis in bone marrow transplant patients.

Adolescent↗

PubMed1991

[Incorporation of transferrin into the erythron in anemic and polycythemic conditions].

A ferrokinetic study was performed in 79 patients, 25 with absolute polycythaemia, 19 with relative polycythaemia and 35 presenting anaemia of different aetiology. The incorporation of transferrin into the erythron (ITE) was estimated on each case. The mean ITE values found in absolute primary and secondary polycythaemia and in secondary polycythaemia were, respectively, 281 +/- 85, 181 +/- 99 and 74 +/- 19 mumol/L tb/d (i.e., micromoles per litre of total blood per day). The mean ITE in iron deficiency anaemia was 110 +/- 43 mumol/L tb/d, in haemolytic anaemia this was 274 +/- 151 mumol/L tb/d, and in patients with myelodysplastic syndromes such values was 116 +/- 49 mumol/L tb/d. Significant differences were found for each group of patients with respect to a normal control group. Such findings are in accordance with the pathophysiology of the different pathologies studied. The values found in haemolytic anaemia and myelodysplastic syndromes are similar to those reported by others. The results of this study stress the advantages of evaluating the erythropoietic activity of the bone marrow by means of the ITE.

Adult↗

PubMedDate not supplied

Higher values of hepatic lipase activity in postmenopause: relationship with atherogenic intermediate density and low density lipoproteins.

OBJECTIVE: To investigate the enzymatic activity of hepatic lipase (HL) in postmenopausal women (PMW) and reproductive age women (RAW); and to evaluate the relationship between this enzyme and the atherogenic intermediate density lipoproteins (IDL) and low density lipoproteins (LDL), and antiatherogenic high density lipoproteins (HDL) and its subfractions (HDL2 and HDL3). DESIGN: We studied 55 PMW receiving no hormonal treatment in a cross-sectional study in comparison with a control group of 55 RAW, matched by body mass index. Follicle-stimulating hormone was > 40 mUI/ml in PMW and 3-12 mUI/ml in RAW. PMW presented at least 1 year of natural menopause and no more than 10 years of amenorrhea with E2 serum concentration < 15 pg/ml. RESULTS: HL activity was significantly higher in PMW versus RAW (14.0 +/- 1.4 vs. 10.9 +/- 0.4 micromol of fatty acids/ml of postheparin plasma, respectively, mean +/- SEM, p < 0.001). In PMW, IDL cholesterol showed a positive correlation with LDL cholesterol (r = 0.28, p < 0.05), and HDL2 cholesterol was inversely correlated with HL activity (r = 0.31, p < 0.05). HL was positively correlated with plasma concentration of LDL cholesterol in both groups (r = 0.27, p < 0.05). The higher values of HL activity and IDL cholesterol were independent of age. CONCLUSIONS: Higher HL activity is associated with a more atherogenic profile in PMW.

Arteriosclerosis↗

PubMedDate not supplied

[Outbreak of multiresistant tuberculosis].

BASIS: Six cases of multiresistant tuberculosis diagnosed in the Hospital of Navarra in 1996 were studied. MATERIAL AND METHODS: Sensitivity tests were carried out using the BACTEC 460TB system against four main anti-tuberculosis medicines: Isoniazid, Streptomycin, Rifampizin and Ethambutol. "Fingerprinting" techniques by means of RFLP with IS 6110 were used in the epidemiological study. RESULTS: Four of the patients were also infected with HIV. All of them had a fatal short-term prognosis. These four showed resistance to the drugs under study; in three resistance was primary, and secondary in the fourth. The molecular study showed that three HIV+ patients had identical patterns of restriction fragment length polymorphism (RFLP). Two were brothers and nosocomial infection was demonstrated in the third. On the other hand, the RPLF pattern of these patients showed great similarity to that of one of the HIV- patients, which suggests a clone origin of the strains, no other epidemiological relationship being found. The RPLF pattern of the other HIV+ patient was identical to that of another of his strains, isolated 14 months before, with the first strain sensitive. The other two patients were HIV- women, and they evolved favourably. In one, who was diabetic, a multiresistant tuberculosis had been diagnosed 7 years before, remaining asymptomatic up until the present. The other involved a secondary resistance due to deficient treatment. CONCLUSIONS: The appearance of multiresistant tuberculosis is a very serious problem amongst HIV+ patients, especially at a time when their life expectancy has improved considerably due to the new therapies. In HIV- patients, multiresistant tuberculosis has a better prognosis. Typification by means of restriction fragment length polymorphism is very useful in clarifying the origin of the cases.

English Abstract↗