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Carlos Martín

Publications and source records attributed to Carlos Martín.

14 recordsLinked to original sources
PubMed2006

Molecular characterisation of Mycobacterium tuberculosis isolates in the First National Survey of Anti-tuberculosis Drug Resistance from Venezuela.

BACKGROUND: Molecular typing of Mycobacterium tuberculosis strains has become a valuable tool in the epidemiology of tuberculosis (TB) by allowing detection of outbreaks, tracking of epidemics, identification of genotypes and transmission events among patients who would have remained undetected by conventional contact investigation. This is the first genetic biodiversity study of M. tuberculosis in Venezuela. Thus, we investigated the genetic patterns of strains isolated in the first survey of anti-tuberculosis drug-resistance realised as part of the Global Project of Anti-tuberculosis Drug Resistance Surveillance (WHO/IUATLD). RESULTS: Clinical isolates (670/873) were genotyped by spoligotyping. The results were compared with the international spoligotyping database (SpolDB4). Multidrug resistant (MDR) strains (14/18) were also analysed by IS6110-RFLP assays, and resistance to isoniazid and rifampicin was characterised. Spoligotyping grouped 82% (548/670) of the strains into 59 clusters. Twenty new spoligotypes (SITs) specific to Venezuela were identified. Eight new inter-regional clusters were created. The Beijing genotype was not found. The genetic network shows that the Latin American and Mediterranean family constitutes the backbone of the genetic TB population-structure in Venezuela, responsible of >60% of total TB cases studied. MDR was 0.5% in never treated patients and 13.5% in previously treated patients. Mutations in rpoB gene and katG genes were detected in 64% and 43% of the MDR strains, respectively. Two clusters were found to be identical by the four different analysis methods, presumably representing cases of recent transmission of MDR tuberculosis. CONCLUSION: This study gives a first overview of the M. tuberculosis strains circulating in Venezuela during the first survey of anti-tuberculosis drug-resistance. It may aid in the creation of a national database that will be a valuable support for further studies.

Antitubercular Agents↗
PubMed2006

Novel streptomycin resistance gene from Mycobacterium fortuitum.

We have isolated the aph(3")-Ic gene, encoding an aminoglycoside 3"-O-phosphotransferase [APH(3")-Ic], from a genomic library of an environmental Mycobacterium fortuitum strain, selecting for streptomycin resistance. APH(3")-Ic phosphorylates and inactivates streptomycin. Similar genes have been described in Streptomyces griseus and plasmid RSF1010. It is also present in some M. fortuitum clinical isolates.

Amino Acid Sequence↗
PubMed2006

Adaptation of a recombinant xylose-utilizing Saccharomyces cerevisiae strain to a sugarcane bagasse hydrolysate with high content of fermentation inhibitors.

Adaptation of a xylose-utilizing genetically engineered strain of Saccharomyces cerevisiae to sugarcane bagasse hydrolysates by cultivation during 353h using medium with increasing concentrations of inhibitors, including phenolic compounds, furaldehydes and aliphatic acids, led to improved performance with respect to ethanol production. The remaining xylose concentration in the medium at the end of the cultivation was 5.2g l(-1), while it was 11gl(-1) in the feed, indicating that approximately half of the xylose was consumed. The performance of the adapted strain was compared with the parental strain with respect to its ability to ferment three bagasse hydrolysates with different inhibitor concentration. The ethanol yield after 24h of fermentation of the bagasse hydrolysate with lowest inhibitor concentration increased from 0.18gg(-1) of total sugar with the non-adapted strain to 0.38gg(-1) with the adapted strain. The specific ethanol productivity increased from 1.15g ethanol per g initial biomass per h with the non-adapted strain to 2.55gg(-1) h(-1) with the adapted strain. The adapted strain performed better than the non-adapted also in the two bagasse hydrolysates containing higher concentrations of inhibitors. The adapted strain converted the inhibitory furaldehydes 2-furaldehyde (furfural) and 5-hydroxymethyl-2-furaldehyde (HMF) at a faster rate than the non-adapted strain. The xylose-utilizing ability of the yeast strain did not seem to be affected by the adaptation and the results suggest that ethanol rather than xylitol was formed from the consumed xylose.

Adaptation, Physiological↗
PubMed2005

Characterization of tetracycline resistance mediated by the efflux pump Tap from Mycobacterium fortuitum.

OBJECTIVES: The aim of this study was to characterize the efflux pump Tap from Mycobacterium fortuitum, to test its sensitivity to well known efflux inhibitors, to study the interaction between tetracycline and these compounds and to test the ability of these compounds to overcome efflux pump-mediated tetracycline resistance. For all these studies, we produced Tap protein in Mycobacterium smegmatis. METHODS: Antibiotic susceptibility tests, tetracycline uptake/efflux experiments and checkerboard synergy tests. RESULTS: Tetracycline uptake/efflux experiments showed that Tap protein from M. fortuitum uses the electrochemical gradient across the cytoplasmic membrane to extrude tetracycline from the cell. This efflux activity is inhibited by carbonyl cyanide m-chlorophenylhydrazone (CCCP) and reserpine, consistent with the decrease in MIC observed in antibiotic susceptibility testing in the presence of these inhibitors. Accumulation was not inhibited in experiments in which o-vanadate and chlorpromazine (CPZ) were tested. Inhibitor-treated cells used glycerol as a carbon source to re-establish the electrochemical gradient across the membrane and to restore efflux activity. CCCP, reserpine and CPZ reduced the MIC of tetracycline in the M. smegmatis strain expressing the Tap protein, whereas o-vanadate increased the MIC. We also observed synergy between tetracycline and CPZ or reserpine, and antagonism with o-vanadate. CONCLUSIONS: The Tapfor efflux pump uses the electrochemical gradient to extrude tetracycline from the cell. This efflux activity can be inhibited by several compounds. This suggests that similar compounds could be used to overcome antibiotic resistance mediated by efflux pumps.

Anti-Bacterial Agents↗
PubMed2005

The virulence-associated two-component PhoP-PhoR system controls the biosynthesis of polyketide-derived lipids in Mycobacterium tuberculosis.

Two-component regulatory signal transduction systems are important elements of the adaptative response of prokaryotes to a variety of environmental stimuli. Disruption of PhoP-PhoR in Mycobacterium tuberculosis dramatically attenuates virulence, implying that this system directly and/or indirectly coordinates the expression of important virulence factors whose identity remains to be established. Interestingly, in knockingout the PhoP-PhoR two-component system in M. tuberculosis Mt103, dramatic changes in the colonial morphology, cording properties, and reactivity of the mutant strain to the basic dye neutral red, all intrinsic properties of tubercle bacilli known to correlate with virulence, were noted. Because deficiencies in the ability of the mutant to form serpentine cords and stain with the dye are likely the results of alterations of its cell envelope composition, we undertook to analyze the lipid content of phoP and phoP-phoR mutants constructed in two different strains of M. tuberculosis. Our results indicate that PhoP coordinately and positively regulates the synthesis of methyl-branched fatty acid-containing acyltrehaloses known to be restricted to pathogenic species of the M. tuberculosis complex, namely diacyltrehaloses, polyacyltrehaloses, and sulfolipids. Evidence is also provided that PhoP but not PhoR is required for the production of these lipids. This work represents an important step toward the functional characterization of PhoP-PhoR and the understanding of complex lipid synthesis in M. tuberculosis.

Bacterial Proteins↗
PubMed2004

Proposed association between the COL1A1 and COL1A2 genes and otosclerosis is not supported by a case-control study in Spain.

Otosclerosis (OTSC) is one of the most common causes of hearing loss in white adults. The COL1A1 and COL1A2 genes coding for type-I collagen have been proposed as candidate genes in the development of OTSC. The COL1A1 gene was recently reported to be associated with the condition on the basis of a population-based case-control study. We report here an independent study of association between COL1A1 and COL1A2 gene polymorphisms and OTSC, in a case-control sample from a population of Caucasian individuals living in Northwest Spain. Specifically, we studied two COL1A1 polymorphisms previously reported to be associated with OTSC, and six COL1A2 polymorphisms. We performed diverse association analyses based on alleles, genotypes, and two-locus haplotypes. We found no evidence supporting the putative link of COL1A1 and COL1A2 genes with OTSC.

Adolescent↗
PubMed2004

Mycobacterium smegmatis displays the Mycobacterium tuberculosis virulence-related neutral red character when expressing the Rv0577 gene.

Neutral red staining is a cytochemical reaction that has been found to be related to Mycobacterium tuberculosis virulence and, therefore, the component involved in it is thought to be a virulence factor. To study the molecular basis of this reaction we constructed an M. tuberculosis cosmid library in Mycobacterium smegmatis and selected recombinant neutral red positive clones. Heterologous complementation identified Rv0577 as the gene responsible for this trait and we have also shown that it is expressed as a single polycistronic unit together with Rv0576 which could also be involved in the neutral red staining.

Cloning, Molecular↗
PubMed2004

IS6110 mediates increased transcription of the phoP virulence gene in a multidrug-resistant clinical isolate responsible for tuberculosis outbreaks.

Drug resistance in Mycobacterium tuberculosis complex strains is solely due to chromosomal mutations that could affect bacterial virulence. Molecular epidemiology studies have shown that resistant strains are less likely to be clustered than susceptible strains. However, a few multidrug-resistant (MDR) M. tuberculosis complex strains have been described as causing outbreaks, suggesting that they have restored virulence or increased transmission. One of the biggest MDR tuberculosis outbreaks documented to date was caused by the B strain of M. bovis. Restriction fragment length polymorphism fingerprinting revealed that the B strain contains two copies of IS6110. Here, we mapped and sequenced the regions flanking the two copies of IS6110 in the B strain. Ligation-mediated PCR showed that one of these IS6110 copies is located within the promoter region of phoP, a transcriptional regulator that is essential for M. tuberculosis virulence. We used PCR to screen 219 MDR M. tuberculosis complex strains (90.4% of all MDR isolates) isolated in Spain between 1998 and 2002 and found that the B strain was the only strain that contained a copy of IS6110 in the phoP promoter. To determine whether IS6110 affects phoP promoter activity in the B strain, we individually cloned the phoP gene and its promoter region (including IS6110 from the B strain and the equivalent region from M. tuberculosis without IS6110 as a control) into a mycobacterial replicative plasmid and transformed M. smegmatis with the resulting plasmid. Primer extension analysis showed that phoP transcription was strongly upregulated when the promoter region contained IS6110, as in the case of the B strain.

Bacterial Proteins↗
PubMed2003

Second primary malignancies in patients with cancer of the head and neck.

OBJECTIVE: Clinical study of second primary malignancies (SPM) in patients with cancer of the head and neck (HNC). Study design and setting Retrospective study over 48 patients with SPMs culled from 636 with HNC seen in 122 months. The minimum follow-up was 18 months, and the setting for the study was the institutional referral center. RESULTS: There was association between the sites of first and second tumor. The SPMs were diagnosed with a constant rate throughout the period of study. Five year-survival rate was 29%. SPM in an advanced stage either outside of the head and neck or synchronous had poor survival. CONCLUSION: The SPMs are a growing problem with better survival after treatment of the first malignancy. SIGNIFICANCE: Regular follow-up is necessary in HNC patients to improve their survival, giving special attention to the development of SPM.

Adult↗
PubMed2002

Interleukin-10 polymorphisms in Spanish multiple sclerosis patients.

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that may be an important regulator in multiple sclerosis (MS) pathogenesis. IL-10 gene contains three single nucleotide polymorphisms (SNPs) and two polymorphic microsatellites in the 5'-flanking region. Our aim was to ascertain if any of these polymorphic markers is associated or linked to MS among Spanish patients. We have genotyped 300 patients and 357 ethnically matched controls for the microsatellites, and most of them also for the promoter SNPs. We included in this study the parents of 63 patients in order to perform a TDT analysis as well. IL-10G12 allele was significantly increased in MS patients (17% versus 11% in controls; p=0.004; p(c)<0.05). No other allele showed a significant difference between patients and controls, and the TDT analysis yielded negative results. The data indicate that IL-10 is not a major susceptibility locus in MS, but in our population it might, however, have a minor role.

Adult↗
PubMed2002

Comparison of the fermentability of enzymatic hydrolyzates of sugarcane bagasse pretreated by steam explosion using different impregnating agents.

Sugarcane bagasse is a potential lignocellulosic feedstock for ethanol production, since it is cheap, readily available, and has a high carbohydrate content. In this work, bagasse was subjected to steam explosion pretreatment with different impregnation conditions. Three parallel pretreatments were carried out, one without any impregnation, a second with sulfur dioxide, and a third with sulfuric acid as the impregnating agent. The pretreatments were performed at 205 degrees C for 10 min. The pretreated material was then hydrolyzed using cellulolytic enzymes. The chemical composition of the hydrolyzates was analyzed. The highest yields of xylose (16.2 g/100 g dry bagasse), arabinose (1.5 g/100 g), and total sugar (52.9 g/100 g) were obtained in the hydrolysis of the SO2 -impregnated bagasse. The H2SO4 -impregnated bagasse gave the highest glucose yield (35.9 g/100 g) but the lowest total sugar yield (42.3 g/100 g) among the three methods. The low total sugar yield from the H2SO4-impregnated bagasse was largely due to by-product formation, as the dehydration of xylose to furfural. Sulfuric acid impregnation led to a three-fold increase in the concentration of the fermentation inhibitors furfural and 5-hydroxymethylfurfural (HMF) and a two-fold increase in the concentration of inhibitory aliphatic acids (formic, acetic, and levulinic acids) compared to the other two pretreatment methods. The total content of phenolic compounds was not strongly affected by the different pretreatment methods, but the quantities of separate phenolic compounds were widely different in the hydrolyzate from the H2SO4-impregnated bagasse compared with the other two hydrolyzates. No major differences in the content of inhibitors were observed in the hydrolyzates obtained from SO2-impregnated and non-impregnated bagasse. The fermentability of all three hydrolyzates was tested with a xylose-utilizing Saccharomyces cerevisiae strain with and without nutrient supplementation. The hydrolyzates of SO2-impregnated and nonimpregnated bagasse showed similar fermentability, whereas the hydrolyzate of H2SO4-impregnated bagasse fermented considerably poorer.

Cellulase↗
PubMed2002

The multidrug transporters belonging to major facilitator superfamily in Mycobacterium tuberculosis.

BACKGROUND: Both intrinsic and acquired multidrug resistance play an important role in the insurgence of tuberculosis. Detailed knowledge of the molecular basis of drug recognition and transport by multidrug transport systems is required for the development of new antibiotics that are not extruded or of inhibitors that block the multidrug transporter and allow traditional antibiotics to be effective. MATERIALS AND METHODS: We have undertaken the inventory of the drug transporters subfamily, included in the major facilitator superfamily (MFS), encoded by the complete genome of Mycobacterium tuberculosis (MTB). These proteins were identified on the basis of their characteristic stretches of amino acids and transmembrane segments (TMS) number. CONCLUSIONS: Genome analysis and searches of homology between the identified transporters and proteins characterized in other organisms revealed 16 open reading frames encoding putative drug efflux pumps belonging to MFS. In the case of two of them, we also have demonstrated that they function as drug efflux proteins.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular characterization of Mycobacterium tuberculosis complex isolates from wild ungulates in south-central Spain.

The role of European wild ungulates in the epidemiology of tuberculosis (TB) is still under discussion. This study describes the geographical distribution and molecular typing of 77 Mycobacterium tuberculosis complex isolates belonging either to M. bovis or to M. caprae, cultivated from hunter harvested red deer (Cervus elaphus) and European wild boar (Sus scrofa) in 24 Spanish localities, and compares them with spoligotypes detected previously in humans, livestock or wild animals, as described in the literature. The distribution of the molecular type patterns suggests that the population of M. tuberculosis complex strains isolated from Spanish wild ungulates is spatially structured despite the lack of important geographical barriers and despite the increasingly frequent wildlife translocations. Red deer and the European wild boar can share the same molecular types in localities in which the M. tuberculosis complex was isolated from both species. Strains of bovine and caprine origin do circulate in the same local wildlife populations. Six out of 11 spoligotypes were similar to types described in human cases. The isolation of TB strains in fenced estates from wild animals that have not had contact with domestic livestock for at least the past two decades, strongly suggests that the M. tuberculosis complex is able to survive in these populations. Therefore, wildlife including cervids and the wild boar need to be considered in the epidemiology and control of tuberculosis.

Animals↗