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Biomedical subjects

M Zúñiga

Publications and source records attributed to M Zúñiga.

At least 19 recordsLinked to original sources
PubMed2004

Characterization of faecal enterococci from rabbits for the selection of probiotic strains.

AIMS: To characterize the facultative anaerobic intestinal microbiota of healthy rabbits, especially enterococci, for the selection of potential probiotic strains. METHODS AND RESULTS: Phenotypic and molecular methods were used to identify enterococcal isolates. Results obtained indicated that enterococcal microbiota widely varied among individuals both in size and in composition. Antibacterial and haemolytic activities, and resistance to acid and bile salts were determined. A small group of strains produced bacteriocins active against listeriae and indigenous clostridia and therefore they were selected as potential probiotics. One such strain, 8G, was assayed for colonization capacity. Results obtained suggested that the fate of the introduced strain depended on the composition of the enterococcal indigenous microbiota. CONCLUSIONS: Enterococcus faecalis and Ent. faecium are the predominant enterococcal species in the gut of rabbits. Other species of lactic acid bacteria were not recovered. SIGNIFICANCE AND IMPACT OF THE STUDY: The enterococcal intestinal microbiota of healthy rabbits has been characterized in detail. Monitoring the fate of an introduced probiotic in vivo is required in order to evaluate potential probiotic strains.

Animals↗
PubMed2003

Multicentre surveillance of antimicrobial resistance in enterococci and staphylococci from Colombian hospitals, 2001-2002.

Invasive isolates of staphylococci and enterococci were collected from 15 tertiary care centres in five Colombian cities from 2001 to 2002. A total of 597 isolates were available for analysis. Identification was confirmed by both automated methods and multiplex PCR assays in a central laboratory. Staphylococcus aureus and coagulase-negative staphylococci (CoNS) corresponded to 49.6% and 29.6% of isolates, respectively, and 20.8% were identified as enterococci. MICs of ampicillin, ciprofloxacin, chloramphenicol, erythromycin, gentamicin, linezolid, oxacillin, rifampicin, teicoplanin, tetracycline, trimethoprim/sulfamethoxazole (SXT) and vancomycin were determined using an agar dilution method as appropriate. Screening for vancomycin-resistant S. aureus was also carried out on brain-heart infusion agar plates supplemented with vancomycin. The presence of mecA and van genes was investigated in methicillin-resistant staphylococci and glycopeptide-resistant enterococci (GRE), respectively. All staphylococci were susceptible to vancomycin, teicoplanin and linezolid. No VISA isolates were found. In S. aureus and CoNS, the lowest rates of resistance were found for SXT (7.4%) and chloramphenicol (10.7%), respectively. Resistance to oxacillin in S. aureus and CoNS was 52% and 73%, respectively. The mecA gene was detected in 97.5% of methicillin-resistant S. aureus isolates. In enterococci, resistance to glycopeptides was 9.7%: vanA (58.3%) and vanB (41.7%) genes were found. Pulsed-field gel electrophoresis indicated that the GRE isolates were closely related. Rates of resistance to ampicillin, ciprofloxacin, chloramphenicol, rifampicin and high levels of gentamicin and streptomycin were 9.7%, 27.4%, 8.9%, 43%, 17% and 28.2%, respectively. All enterococci were susceptible to linezolid.

Anti-Bacterial Agents↗
PubMed2002

Cellular biomarkers in native and transplanted populations of the mussel Perumytilus purpuratus in the intertidal zones of San Jorge Bay, Antofagasta, Chile.

Cellular biomarkers were measured in the mussel Perumytilus purpuratus from intertidal zones of San Jorge Bay, Antofagasta, Chile. They were also used to measure sublethal effects on individuals exposed to Cu under laboratory conditions. Lysosomal stability in hemocytes, and the degree of vacuolization and the content of lipofuscin granules in digestive cells were the cellular responses measured. Three study sites were established in San Jorge Bay: Coloso, E.R., and Reference. Both E.R. and Coloso receive effluent discharges. Reference does not receive any sewage discharges. Before sampling, mussels from Reference were transplanted into the intertidal zone of each site. Samplings were obtained at the beginning, after 45 days, and after 90 days after transplantation. Seawater samples for total dissolved Cu analysis and adult mussels ( P. purpuratus) from native and transplanted populations were collected each time. Cellular biomarkers and Cu concentrations in gonads, gills, and remaining tissues (gut and muscle) were measured. Mussels from Reference were exposed to sublethal Cu concentrations (5, 10, 20, 30, 40, and 80 microg x L(-1)) during 45 days under laboratory conditions. Lysosomal stability was measured in mussel hemocytes by means of the neutral red retention assay. The degree of vacuolization and the extent of lipofuscin granules were determined in the digestive cells by image analysis of histological sections stained with the Schmorl's method. Seawater Cu concentrations and tissue Cu concentrations in P. purpuratus were higher in E.R. than in Reference and Coloso (p < 0.02). Native mussel populations from E.R. showed lower lysosomal stability (p < 0.05), higher vacuolization degree (p < 0.001), and lower amounts of lipofuscin granules (p < 0.001) than those from Coloso and Reference. Transplanted mussel to E.R. showed significant reduction in lysosomal stability (p < 0.05) and in extent of lipofuscin granules (p < 0.05) and significant increase in vacuolization degree (p < 0.05), whereas Reference and Coloso are not significantly dissimilar between them. Seawater Cu concentration was positively correlated with Cu content in gonads ( r2 = 0.61; p < 0.02), gills ( r2 = 0.66; p < 0.01), remaining tissues ( r2 = 0.56; p < 0.05), and the degree of vacuolization ( r2 = 0.65; p < 0.01) and negatively with lysosomal stability ( r2 = 0.79; p < 0.001) and lipofuscin granules extent ( r2 = 0.53; p < 0.05). Mussels exposed to Cu under laboratory conditions showed decreased lysosomal stability (over 30 microg Cu x L(-1)) (p < 0.02) and increased degree of vacuolization (at 80 microg Cu x L(-1)) (p < 0.05) and an increased lipofuscin granules extent (although differences among treatments were not statistically significant).

Animals↗
PubMed2001

Construction of compatible wide-host-range shuttle vectors for lactic acid bacteria and Escherichia coli.

A new collection of shuttle cloning vectors has been constructed that can be used in a broad host range, because they carry replication origins which are functional in Escherichia coli (p15A, pWV01, ColE1), Lactococcus lactis, lactobacilli, and Bacillus subtilis (pAMbeta1, pWV01). These plasmids contain the lacZ-T1T2 cassette from pJDC9, which allows the X-gal selection and cloning of DNA fragments that could cause plasmid instability in E. coli. In addition, they have been proved to be structurally and segregationally stable in Lactobacillus casei, in which their copy number has been determined by real-time quantitative PCR. Furthermore, the antibiotic resistance markers (beta-lactamase, chloramphenicol acetyl transferase, and erythromycin transacetylase) and the theta and rolling circle replicating origins have been combined to obtain this set of compatible plasmids (pIA family) that can be cotransformed, both in lactic acid bacteria and in E. coli.

Bacillus subtilis↗
PubMed2000

[Clinical manifestations of heterozygote familial hypercholesterolemia in Spain. Study of 301 cases from the central and northern areas].

RATIONALE: To characterize clinical manifestations of familial hypercholesterolemia (FH) in Spain. PATIENTS AND METHODS: A group of 301 cases of FH from central and north regions of Spain. RESULTS: With a mean (SD) cholesterol level of 346 (58) mg/dl, only 7.6% of the patients have xanthomas and 20% ischaemic heart disease. 51% have a familial history of ischaemic heart disease. CONCLUSIONS: Different from the results of literature, xanthomas are very infrequent in FH in Spain, so diagnosis should be suspected from other data. The high prevalence of familial history of ischaemic heart disease supports the usefulness of this feature as a marker for diagnosis and prevention.

Adult↗
PubMed2000

Degradation of proteins from the ER of S. cerevisiae requires an intact unfolded protein response pathway.

To dissect the requirements of membrane protein degradation from the ER, we expressed the mouse major histocompatibility complex class I heavy chain H-2K(b) in yeast. Like other proteins degraded from the ER, unassembled H-2K(b) heavy chains are not transported to the Golgi but are degraded in a proteasome-dependent manner. The overexpression of H-2K(b) heavy chains induces the unfolded protein response (UPR). In yeast mutants unable to mount the UPR, H-2K(b) heavy chains are greatly stabilized. This defect in degradation is suppressed by the expression of the active form of Hac1p, the transcription factor that upregulates UPR-induced genes. These results indicate that induction of the UPR is required for the degradation of protein substrates from the ER.

Animals↗
PubMed1998

Structural and functional analysis of the gene cluster encoding the enzymes of the arginine deiminase pathway of Lactobacillus sake.

Lactobacillus sake can use arginine via the arginine deiminase (ADI) pathway. We designed degenerate primers based on an alignment of known sequences of ornithine transcarbamoylase (OTC)-encoding genes in order to amplify the L. sake counterpart sequences by PCR. Screening a genomic library of L. sake in lambdaEMBL3 allowed us to isolate a clone containing a 10-kb L. sake genomic DNA insert. Sequence analysis revealed that the genes involved in arginine catabolism were clustered and encoded ADI (arcA), OTC (arcB), carbamate kinase (arcC), and a putative carrier with high similarity to the arginine/ornithine antiporter of Pseudomonas aeruginosa (arcD). Additionally, a putative transaminase-encoding gene (arcT) was located in this region. The genes followed the order arcA arcB arcC arcT arcD, which differs from that found in other microorganisms. arcA, arcB, arcC, and arcD mutants were constructed, and the ADI pathway was impaired in all of them. Transcriptional studies indicated that arcA gene is subject to catabolite repression, and under the conditions used, several transcripts could be detected, suggesting the existence of different initiation sites or processing of a larger mRNA.

Bacterial Proteins↗
PubMed1998

[Microbial etiology of mild and moderate pelvic inflammatory disease].

Pelvic inflammatory disease (PID) is one of the most severe complications of sexually transmitted disease (STD). It can be due to the ascending of normal endogenous microorganisms of the female genital tract or the infection by microorganisms related to STD as Chlamydia trachomatis and Neisseria gonorrhoeae. PID leads to serious gynecoobstetric consequences as infertility and ectopic pregnancy. Clinicians face the problem of knowing the ethiology of PID in order to treat appropriatly patients with this clinical diagnosis. So that, this work pretends to establish what kind of microorganisms are implicated in PID. A proper isolation and identification of microorganisms achieved by culture of lower genital tract samples from endocervix, endometrium and peritoneal fluid, leading to a betther, specific and proper treatment of this disease.

Anti-Bacterial Agents↗
PubMed1996

Transposons Tn916 and Tn925 can transfer from Enterococcus faecalis to Leuconostoc oenos.

The streptococcal transposons Tn916 and Tn925 were transferred to several strains of Leuconostoc (Ln.) oenos using the filter mating method. The insertion of both transposons into the chromosome occurred at different sites. Transconjugants of Ln. oenos carrying Tn916 could serve as donors in mating experiments with Lactococcus lactis LM2301. Further analysis of L. lactis LM2301 transconjugants showed that the insertion of the transposon Tn916 into the chromosome was site-specific. These studies establish a basis for the initiation of genetic studies in this Leuconostoc species since there are no efficient conjugal or transformation systems previously described for this microorganism.

Conjugation, Genetic↗
PubMed1996

Nucleotide sequence of plasmid p4028, a cryptic plasmid from Leuconostoc oenos.

The Leuconostoc oenos plasmid p4028 was cloned in pBlueScript (SK+), and its complete nucleotide sequence was determined. The analysis of the nucleotide sequence revealed five open reading frames, all of them located on the same strand and grouped in two clusters separated by a short noncoding stretch. A similarity search against the other sequences deposited in the EMBL and GenBank databases showed that p4028 has no significant similarity with any of the sequences checked. Nevertheless, a putative ATP-binding motif was found in ORF2. A more detailed analysis of this ORF suggests that it could encode for a DNA-dependent ATPase.

Amino Acid Sequence↗
PubMed1992

Immunoprophylactic trial with combined Mycobacterium leprae/BCG vaccine against leprosy: preliminary results.

In an attempt to find a vaccine that gives greater and more consistent protection against leprosy than BCG vaccine, we compared BCG with and without killed Mycobacterium leprae in Venezuela. Close contacts of prevalent leprosy cases were selected as the trial population since they are at greatest risk of leprosy. Since 1983, 29,113 contacts have been randomly allocated vaccination with BCG alone or BCG plus 6 x 10(8) irradiated, autoclaved M leprae purified from the tissues of infected armadillos. We excluded contacts with signs of leprosy at screening and a proportion of those whose skin-test responses to M leprae soluble antigen (MLSA) were 10 mm or more (positive reactions). By July, 1991, 59 postvaccination cases of leprosy had been confirmed in 150,026 person-years of follow-up through annual clinical examinations of the trial population (31 BCG, 28 BCG/M leprae). In the subgroup for which we thought an effect of vaccination was most likely (onset more than a year after vaccination, negative MLSA skin-test response before vaccination), leprosy developed in 11 BCG recipients and 9 BCG/M leprae recipients; there were 18% fewer cases (upper 95% confidence limit [CL] 70%) in the BCG/M leprae than in the BCG alone group. For all cases with onset more than a year after vaccination irrespective of MLSA reaction the relative efficacy was 0% (upper 95% CL 54%; 15 cases in each vaccine group). Retrospective analysis of data on the number of BCG scars found on each contact screened suggested that BCG alone confers substantial protection against leprosy (vaccine efficacy 56%, 95% CL 27-74%) and there was a suggestion that several doses of BCG offered additional protection. There is no evidence in the first 5 years of follow-up of this trial that BCG plus M leprae offers substantially better protection against leprosy than does BCG alone, but the confidence interval on the relative efficacy estimate is wide.

BCG Vaccine↗
PubMed1989

Dynamics of Microbial Populations during Fermentation of Wines from the Utiel-Requena Region of Spain.

The dynamics of fungi, yeasts, and lactic acid bacteria during fermentation of four musts were studied. Fungi disappeared quickly in the fermenting must. The lactic acid bacteria population diminished during alcoholic fermentation, then they increased and performed malolactic fermentation. Yeasts grew quickly, reaching maximum populations at different times depending on the vinification treatment.

Journal Article↗