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Biomedical subjects

M Casal

Publications and source records attributed to M Casal.

At least 19 recordsLinked to original sources
PubMed2004

Activity of rifampin against Mycobacterium tuberculosis in a reference center.

Rifampin is a bactericidal antibiotic that acts both on extra- and intracellular bacilli. It inhibits RNA synthesis by binding to the beta-subunit in the RNA polymerase. A study was conducted on rifampin resistance from 1993 to 2002 with 1,794 Mycobacterium tuberculosis strains submitted to Mycobacteria Reference Center, Córdoba, Spain. A total of 1,460 of these strains came from pulmonary specimens and 235 from extrapulmonary specimens. All strains were identified by conventional morphological, bacteriological, biochemical, genetic, and chromatographic methods. For 99 strains, the source was not indicated. Initially, the BACTEC 460 TB system was used for antibiotic sensitivity testing. Since 1996, the ESP II system was also used. The strains ATCC27294 (sensitive to streptomycin, rifampin, ethambutol, and isoniazid) and ATCC38838 (resistant to rifampin) were used as controls. The resistance degree detected was 10.03%, of which 1.2% and 8.7% corresponded to primary and secondary resistances, respectively. A total of 137 strains showed multiresistance. The surveillance of resistance and of the potential factors that may lead to an increase in resistance is thus warranted.

Antibiotics, Antitubercular↗
PubMed2003

Current interest of isoniazid in the chemotherapy of tuberculosis in the light of its in vitro activity.

Isoniazid is one of the most useful drugs for the treatment of tuberculosis. However, in the last few years treatment with this drug has become long, complicated, and occasionally inefficient because of the increasing number of cases with resistance. The aim of our work was to know the isoniazid resistance level of 1,496 Mycobacterium tuberculosis strains that were submitted to the Mycobacteria Reference Center, Córdoba, during the years 1993-2000. A total of 1,186 strains were from pulmonary sources and 196 from extrapulmonary sources; no source was provided for 114 strains. All M. tuberculosis strains were previously identified by different methods. For sensitivity testing, the BACTEC 460 TB system was used initially and then the ESP II system was also used. The control strains used in this study were ATCC27294 (sensitive to SM, RP, EB, and INH) and ATCC35822, resistant to INH. The overall resistance rate obtained was 14.8%, of which 2.3% and 1.4% accounted for primary and secondary resistance types, respectively. Ninety-six out of the 221 resistant strains were resistant to INH only, and 8 strains were resistant to INH plus SM. A total of 117 multiresistant strains were found. An apparent increase in the resistance rate to INH in the last few years was observed. Secondary resistance has decreased, whereas primary resistance has increased. A continuous surveillance of resistance is required and, therefore, any patient with tuberculosis should undergo sensitivity testing to confirm therapy to be used.

Antitubercular Agents↗
PubMed2003

[Susceptibility of Streptococcus pyogenes isolates from pharyngeal exudates in Cordoba (Spain)].

Streptococcus pyogenes is an important human pathogen. Betalactams are still the drug of choice for the treatment of infections caused by this microorganism. In recent years an increase in the use of macrolides for initial treatment in respiratory infections has been observed; consequently, the number of macrolide-resistant isolates has also increased. We investigated the susceptibility of S. pyogenes to penicillin, erythromycin, clarithromycin and clindamycin in Cordoba during 2000, 2001 and the first 6 months of 2002. We obtained 100 isolates of S. pyogenes from 1232 pharyngeal exudates, all of which were susceptible to penicillin and 39 of which were resistant to erythromycin and clarithromycin. Twenty-six of these 39 isolates were susceptible to clindamycin.

Clarithromycin↗
PubMed2003

[Streptomycin as second-line chemotherapy for tuberculosis].

Streptomycin was the first antibiotic to be used against Mycobacterium tuberculosis. It was used for years in monotherapy regimens, thereby resulting in the appearance of resistance and the relegation of its use. The resistance detected against drugs currently employed has led to a renewed interest in streptomycin. Its mechanism of action is centered on the ribosome, inhibiting the protein synthesis of the microbacteria. Resistance appears when mutations in the genes codifying for rRNA 16S and for protein S12 are produced. We studied the use of streptomycin against 899 M. tuberculosis strains, 713 of which were from pulmonary and 186 from extrapulmonary isolates. The BACTEC 460 TB system was initially employed as was the ESP II system. As controls, the ATCC27294 pattern strains (susceptible to streptomycin, rifampicin, ethambutol and isoniazid) were used. The results showed 2.1% secondary resistance in all the cases. Multiresistance was observed in 12 strains.

Antitubercular Agents↗
PubMed2003

[Methicillin resistant Staphylococcus aureus from clinical samples in Cordoba (Spain)].

Increases in methicillin-resistant Staphylococcus aureus (MRSA) strains and in isolates with reduced susceptibility to glucopeptides have become an important problem in the epidemiology of Gram-positive microorganisms. All the consecutive S. aureus collected in our hospital from 1995 to 2001 were studied. Of the 4531 isolates 24.23% were methicillin resistant in this period. The highest number of methicillin-resistant strains were found in wound exudates. In recent years an almost 20% increase in MRSA has occurred in our hospital. As MRSA strains are an important problem in our area and their prevalence is on the rise, as is multiresistance, the monitoring and control of MRSA strains in our hospitals is necessary.

Health Facilities↗
PubMed2003

[Trends in antimicrobial resistance of Pseudomonas aeruginosa, Escherichia coli and Bacteroides fragilis (1997-2001)].

A study was conducted from 1997 to 2001 on the trends of the antibiotic resistance of Pseudomonas aeruginosa, Escherichia coli and Bacteroides fragilis in a Spanish multicenter study involving 26 hospitals. During the five years of the study the susceptibility by 81,779 strains of P. aeruginosa, 306,689 strains of E. coli and 2866 strains of B. fragilis to at least one antibiotic were studied. When the three microorganisms were considered together, meropenem (3.49%), piperacillin-tazobactam (5.54%) and imipenem (5.27%) were the antibiotics to which they showed the lowest resistance rate.

Anti-Bacterial Agents↗
PubMed2002

Relationship between protein kinase C and derepression of different enzymes.

The PKC1 gene in the yeast Saccharomyces cerevisiae encodes for protein kinase C which is known to control a MAP kinase cascade consisting of different kinases: Bck1, Mkk1 and Mkk2, and Mpk1. This cascade affects the cell wall integrity but the phenotype of pkc1Delta mutants suggests additional targets that have not yet been identified [Heinisch et al., Mol. Microbiol. 32 (1999) 671-680]. The pkc1Delta mutant, as opposed to other mutants in the MAP kinase cascade, displays defects in the control of carbon metabolism. One of them occurs in the derepression of SUC2 gene after exhaustion of glucose from the medium, suggesting an involvement of Pkc1p in the derepression process that is not shared by the downstream MAP kinase cascade. In this work, we demonstrate that Pkc1p is required for the increase of the activity of enzymatic systems during the derepression process. We observed that Pkc1p is involved in the derepression of invertase and alcohol dehydrogenase activities. On the other hand, it seems not to be necessary for the derepression of the enzymes of the GAL system. Our results suggest that Pkc1p is acting through the main glucose repression pathway, since introduction of an additional mutation in the PKC1 gene in yeast strains already presenting mutations in the HXKII or MIG1 genes does not interfere with the typical derepressed phenotype observed in these single mutants. Moreover, our data indicate that Pkc1p participates in this process through the control of the cellular localization of the Mig1 transcriptional factor.

Agar↗
PubMed2002

Investigation of the in vitro activity of streptomycin against Mycobacterium tuberculosis.

Streptomycin was the first antibiotic used against Mycobacterium tuberculosis. It was used for years in monotherapy regimens, leading to the emergence of resistance; therefore, its use gradually waned. Given the resistance rates detected with current antituberculosis drugs, the use of streptomycin has gained renewed interest. The mechanism of action of streptomycin is inhibition of protein synthesis of mycobacteria in the ribosome. Resistance emerges when mutations appear in genes encoding 16S rRNA and protein S12. The activity of streptomycin against 1,496 M. tuberculosis strains was investigated; 1,186 and 196 strains corresponded to pulmonary and extrapulmonary specimens, respectively. For 114 strains, the source was not indicated. Initially, the BACTEC 460 TB system was used for antibiotic susceptibility testing. Since 1996, the ESP II system was used. The strains ATCC27294 (sensitive to streptomycin, rifampin, ethambutol, and isoniazid) and ATCC35820 (resistant to streptomycin) were used as controls. An overall resistance rate of 2.2% was obtained. In all cases secondary resistance was observed. Multiresistance was observed in 23 strains.

Antibiotics, Antitubercular↗
PubMed2002

Animal models for mucopolysaccharidoses and their clinical relevance.

The mucopolysaccharidoses (MPS) are characterized by the accumulation of glycosaminoglycans (GAG) and result from the impaired function of one of 11 enzymes required for normal GAG degradation. MPS II was the first MPS to be defined clinically in humans and is caused by deficient activity of the enzyme iduronate-2-sulphatase. MPS VI was the first MPS recognized in an animal; since then, all but MPS IIIC and IX have been described as naturally occurring in animals or made by knock-out technology. As in humans, all are inherited as autosomal recessive traits, except for MPS II, which is X-linked. Most animal colonies have been established from single related heterozygous animals, making the affected offspring homozygous for the same mutant allele. Importantly, these models have disease pathology that is similar to that seen in humans, making the animals extremely valuable for the investigation of disease pathogenesis and the testing of therapies. Large animal homologues are similar to humans in natural genetic diversity, approaches to therapy and care, and the possibility of evaluating long-term effects of treatment. Therapeutic strategies for MPS include enzyme replacement therapy, heterologous bone marrow transplantation, and somatic cell gene transfer, all of which have been tested in animals with some success.

Animals↗
PubMed2002

GenoType mycobacterium assay for identification of mycobacterial species isolated from human clinical samples by using liquid medium.

The GenoType Mycobacterium assay was used to identify 98 mycobacteria isolates by using liquid cultures from positive BACTEC, MGIT, and ESP bottles. This system identifies 16 mycobacteria. There was complete agreement between the GenoType results and the laboratory identifications for Mycobacterium tuberculosis complex and other Mycobacterium spp. GenoType also identified mixed mycobacterial infections.

Bacteriological Techniques↗
PubMed2001

The putative monocarboxylate permeases of the yeast Saccharomyces cerevisiae do not transport monocarboxylic acids across the plasma membrane.

We have characterized the monocarboxylate permease family of Saccharomyces cerevisiae comprising five proteins. We could not find any evidence that the monocarboxylate transporter-homologous (Mch) proteins of S. cerevisiae are involved in the uptake or secretion of monocarboxylates such as lactate, pyruvate or acetate across the plasma membrane. A yeast mutant strain deleted for all five MCH genes exhibited no growth defects on monocarboxylic acids as the sole carbon and energy sources. Moreover, the uptake and secretion rates of monocarboxylic acids were indistinguishable from the wild-type strain. Additional deletion of the JEN1 lactate transporter gene completely blocked uptake of lactate and pyruvate. However, uptake of acetate was not even affected after the additional deletion of the gene YHL008c, which had been proposed to code for an acetate transporter. The mch1-5 mutant strain showed strongly reduced biomass yields in aerobic glucose-limited chemostat cultures, pointing to the involvement of Mch transporters in mitochondrial metabolism. Indeed, intracellular localization studies indicated that at least some of the Mch proteins reside in intracellular membranes. However, pyruvate uptake into isolated mitochondria was not affected in the mch1-5 mutant strain. It is concluded that the yeast monocarboxylate transporter-homologous proteins perform other functions than do their mammalian counterparts.

Biomass↗
PubMed2001

Expression of the lactate permease gene JEN1 from the yeast Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, lactate permease induction by lactic acid took place after transcription of JEN1. JEN1 transcripts were undetectable 10 min after the addition of a pulse of glucose to YP-lactic acid exponentially growing cells, while the permease activity ceased after 50 min. A value of 15.1 min was found for the half-life of JEN1 mRNA, showing the involvement of a glucose-induced mechanism of mRNA degradation. The rapid decline of the carrier activity upon glucose addition points to the existence of an irreversible carbon catabolite inactivation process. Isogenic strains, deleted in genes encoding enzymes involved in lactic acid metabolism, did not express JEN1, indicating an association of the intracellular metabolism of the acid to the transcription of the permease gene. The carbon sources capable of inducing JEN1 transcription were dependent on the strain. Distinct posttranslation mechanisms appeared to be involved in the lactate carrier activity.

Carrier Proteins↗
PubMed2001

Detection of embB codon 306 mutations in ethambutol resistant Mycobacterium tuberculosis directly from sputum samples: a low-cost, rapid approach.

Substitutions of codon 306 in the gene embB are the most common mutations found in ethambutol resistant Mycobacterium tuberculosis. The characterization of these mutations has been hampered by the need for prior cultivation of the mycobacteria, or the need for DNA sequencing, or both. Here, we describe a simple and culture-independent technique to detect embB codon 306 mutations directly from sputum samples, requiring little more than a PCR machine and a simple agarose minigel. There is no need for labelled probes or DNA sequencing. In a preliminary test of feasibility, interpretable results were obtained from 21 of 24 selected sputum samples, 12 of which were determined to contain ethambutol resistant M. tuberculosis after culture. All of six samples with embB codon 306 mutations were correctly identified. Although an exact validation of this technique is beyond the scope of this technical report, we conclude from well-known embB codon 306 mutation prevalence figures that approximately one half of EMB resistant cases could already be predicted within 2 working days, with little equipment or hands-on time needed, instead of weeks required for conventional resistance testing.

Chemistry, Clinical↗
PubMed2001

Unusual presentation of a pancreatic insulinoma in helical CT and dynamic contrast-enhanced MR imaging: case report.

Insulinomas are pancreatic neoplasms that can be radiologically characterized typically because of their tendency to present intense and early contrast enhancement with a wash-out phenomenon. In this sense, we report an unusual case of a hypovascular solid pancreatic insulinoma confirmed with surgery and pathologic analysis, in a patient with normal serum insulin levels. In the two-phase helical CT, the mass behaved as a hypodense lesion with respect to the surrounding pancreatic parenchyma during the arterial phase and as a hypointense lesion during the dynamic contrast-enhanced MR imaging. Pathologic examination demonstrated a hypercellular tumor with poor vascularization of intervening stroma which showed prominent amyloid deposits.

Aged↗
PubMed2001

Multicenter study of incidence of Mycobacterium marinum in humans in Spain.

A retrospective survey was carried out on the epidemiological monitoring of the isolation incidence of Mycobacterium marinum in 21 laboratories, in an attempt to gain an insight into the frequency of its isolation in Spain. From 1991 to 1998, 39 cases (22 male and 17 female) of bacteriologically confirmed M. marinum infection were accumulated. The majority of the cases (35) were fish related. The clinical presentation usually suggested sporotrichosis, with the majority of skin eruptions appearing on the hand (32 cases). For treatment, minocycline was recommended as the drug of choice in 12 cases, rifampicin in eight cases and clarithromycin and ethambutol in seven cases.

Adolescent↗