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Biomedical subjects

A Torres

Publications and source records attributed to A Torres.

At least 19 recordsLinked to original sources

Two decades of imipenem therapy.

Imipenem, the first carbapenem discovered, was developed more than two decades ago in response to an unmet need for a highly potent, broad-spectrum antimicrobial agent with a strong safety profile. It has since been used to treat more than 26 million patients. In an era where antibiotic use has driven antibiotic resistance, choosing appropriate initial therapy for serious infection is critical. Appropriate antibiotic regimens must cover all likely pathogens, be administered promptly at the correct dosage and dosing interval, be well tolerated and prevent the emergence of resistance. While imipenem was initially reserved for use in intractable, serious infections, the benefits of early aggressive therapy are now known, making imipenem a core agent in de-escalation therapy due to proven efficacy and safety for indications such as nosocomial pneumonia, intra-abdominal infection, sepsis and febrile neutropenia. De-escalation therapy with an agent such as imipenem minimizes resistance development by initiating aggressive initial treatment and then tailoring therapy based on patient response and culture results, switching to a less expensive, narrower spectrum antibiotic regimen or shortening the duration of therapy. Imipenem has maintained sustained clinical efficacy, tolerability and in vitro activity against important bacterial pathogens for two decades. We review the factors that continue to make imipenem as appropriate an agent for de-escalation therapy now as it was 20 years ago.

Anti-Bacterial Agents↗

Alpha-1-antitrypsin deficiency: optimal therapeutic regimen based on population pharmacokinetics.

BACKGROUND: Exogenous doses of 60 mg/kg alpha(1)-antitrypsin (AAT) every 7 days are recommended in patients with severe AAT deficiency. However, long term administration of weekly doses is not well accepted by patients. Using pharmacokinetic simulations, we evaluated whether steady state minimum concentrations of total AAT can be maintained above the threshold of 0.5 g/l with longer intervals between doses. METHODS: Several sets of exogenous AAT versus time simulations were studied using a non-linear mixed effect approach with dosage regimens every 7, 14, 21, and 28 days. For each regimen the mean exogenous AAT trough concentrations and 5/95th percentiles were determined. The results obtained were applied to estimate the individual optimal dose at 7, 14, and 21 days in six patients using Bayesian analysis. RESULTS: The simulations showed that a dose of 50 mg/kg AAT every 7 days was sufficient to obtain nadir concentrations. Doses of 120 and 100 mg/kg every 14 days were also adequate, but 180 mg/kg given every 21 days required total AAT monitoring to avoid underdosage. Longer intervals were inappropriate. Dosage individualisation confirmed that AAT infusions given every 14 days maintained the nadir level of 0.5 g/l without a significant dose increase compared with current practice. When the time span between doses was fixed at 21 days, a mean relative AAT dose enhancement of 91% and 13%, respectively, was required to achieve sustained total AAT concentrations above the target level for 100% and 85% of the interval between doses. CONCLUSIONS: It is feasible to extend the interval between doses of AAT to 14 or 21 days to achieve adequate trough total AAT concentrations. This study might be used as a starting point for clinical evaluation of the regimens described.

Aged↗

Presentation and role of transplantation in adult patients with type 1 primary hyperoxaluria and the I244T AGXT mutation: Single-center experience.

Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder characterized by allelic and clinical heterogeneity. We aim to describe the presentation and full single-center experience of the management of PH1 patients bearing the mutation described in our community (I244T mutation+polymorphism P11L). Since 1983, 12 patients with recurrent renal lithiasis have been diagnosed with PH1 and renal failure in the Canary Islands, Spain. Diagnostic confirmation was based on the presence of oxalosis in undecalcified bone or kidney allograft biopsy, reduced alanine:glyoxylate aminotransferase activity in liver biopsy, and blood DNA analysis. Patients underwent different treatment modalities depending on individual clinical circumstances and therapeutic possibilities at the time of diagnosis: hemodialysis, isolated kidney, simultaneous liver-kidney, or pre-emptive liver transplantation. In all cases, the presentation of advanced renal disease was relatively late (>13 years) and no cases were reported during lactancy or childhood. The eight patients treated with hemodialysis or isolated kidney transplantation showed unfavorable evolution leading to death over a variable period of time. In contrast, the four patients undergoing liver transplantation (three liver+kidney and one pre-emptive liver alone) showed favorable long-term allograft and patient survival (up to 12 years follow-up). In conclusion, in this PH1 population, all bearing the I244T mutation, the development of end-stage renal disease was distinctive during late adolescence or adulthood. Our long-term results support pre-emptive liver transplantation at early stages of renal failure, and kidney-liver transplantation for those with advanced renal disease.

Adolescent↗

ASPP1, a common activator of TP53, is inactivated by aberrant methylation of its promoter in acute lymphoblastic leukemia.

We have analyzed the regulation and expression of ASPP members, genes implicated in the regulation of the apoptotic function of the TP53 tumor-suppressor gene, in acute lymphoblastic leukemia (ALL). Expression of ASPP1 was significantly reduced in ALL and was dependent on hypermethylation of the ASPP1 gene promoter. Abnormal ASPP1 expression was associated with normal function of the tumor-suppressor gene TP53 in ALL. The analyses of 180 patients with ALL at diagnosis showed that the ASPP1 promoter was hypermethylated in 25% of cases with decreased mRNA expression. Methylation was significantly higher in adult ALL vs childhood ALL (32 vs 17%, P = 0.03) and T-ALL vs B-ALL (50 vs 9%, P = 0.001). Relapse rate (62 vs 44%, P = 0.05) and mortality (59 vs 43%, P = 0.05) were significantly higher in patients with methylated ASPP1. DFS and OS were 32.8 and 33.7% for patients with unmethylated ASPP1 and 6.1 and 9.9% for methylated patients (P < 0.001 y P < 0.02, respectively). On the multivariate analysis, methylation of the ASPP1 gene promoter was an independent poor prognosis factor in ALL patients. Our results demonstrate that decreased expression of ASPP1 in patients with ALL is due to an abnormal methylation of its promoter and is associated with a poor prognosis.

Adaptor Proteins, Signal Transducing↗

Implications of COPD in patients admitted to the intensive care unit by community-acquired pneumonia.

The mortality rate of chronic obstructive pulmonary disease (COPD) patients with community-acquired pneumonia (CAP) is reported to be low. However, studies carried out to date have included <20% of critically ill patients. The current authors performed a secondary analysis of a prospective study evaluating 428 immunocompetent patients admitted to the intensive care unit (ICU) for severe CAP. In total, 176 COPD patients were compared with 252 non-COPD patients. In COPD patients, ICU mortality (odds ratio (OR) 1.58; 95% confidence interval (CI) 1.01-1.43) and mechanical ventilation (OR 2.78; 95% CI 1.63-4.74) rates were higher than in non-COPD patients. The ICU mortality was 39% for COPD patients initially intubated and 50% for those who failed noninvasive ventilation. The proportion of patients who were males, aged >/=70 yrs, smokers and who had chronic heart disease or Pseudomonas aeruginosa were higher in COPD patients. Inappropriate empirical antibiotic therapy was associated with higher mortality (OR 3.8; 95% CI 1.19-12.6). ICU mortality in COPD patients with adequate therapy was associated with bilateral pneumonia (OR 2.32; 95% CI 1.18-4.53) and shock (OR 3.53; 95% CI 1.31-9.71). In conclusion, chronic obstructive pulmonary disease patients hospitalised with community-acquired pneumonia in the intensive care unit had higher mortality and need of mechanical ventilation when compared with patients without chronic obstructive pulmonary disease.

Aged↗

Oxacillin-resistant and multidrug-resistant Staphylococcus aureus in Lima, Peru.

In a hospital in Lima, Peru, a review of 103 Staphylococcus aureus infections was conducted during 2002. The prevalence of oxacillin-resistant S. aureus strains was 68%; 25% of strains were resistant to multiple drugs. Previous use of antibiotics and undergoing a surgical procedure during the current hospital stay were associated with the presence of an oxacillin-resistant S. aureus strain.

Adult↗

Impact of initial antibiotic choice on mortality from pneumococcal pneumonia.

To determine the impact of initial antimicrobial choice on 30-day mortality rate in patients with community-acquired pneumonia due to Streptococcus pneumoniae (CAP-SP), a prospective, observational study was conducted in 35 Spanish hospitals. A total of 638 patients with CAP-SP were identified. Antimicrobials were chosen by the attending physician. Patients were grouped into the following categories: beta-lactam monotherapy (n = 251), macrolide monotherapy (n = 37), beta-lactam plus macrolide (n = 198), levofloxacin alone/combination (n = 48), and other combinations (n = 104). The reference category was beta-lactam+macrolide. The 30-day survival probability was 84.9%. Using multivariate survival analysis, factors related to mortality in the entire population were: bilateral disease, suspected aspiration, shock, HIV infection, renal failure and pneumonia severity index (PSI) score Class IV versus I-III and categories V versus I-III. The association of beta-lactams+macrolides was not better than the use of beta-lactams alone. The current authors analysed the different groups of patients with significant mortality/morbidity: intensive care unit, PSI Class >III, renal failure, chronic lung disease and bacteraemia. Only in patients with PSI Class >III, who had undergone initial antimicrobial choice classified as other combinations, were associated with higher mortality. In conclusion, the current authors have not demonstrated an independent association between initial antimicrobial regimen and 30-day mortality in community-acquired pneumococcal pneumonia patients, except for those with a higher pneumonia severity index score.

Adolescent↗

Addition of a macrolide to a ss-lactam in bacteremic pneumococcal pneumonia.

In the study presented here, data collected prospectively from 340 adult patients hospitalised in five countries with bacteremic pneumococcal CAP and treated with a ss-lactam +/- a macrolide were analysed retrospectively to evaluate the efficacy of this antimicrobial combination. Univariate and multivariate analyses revealed no significant effect on case fatality rate when a macrolide/ss-lactam regimen was used as initial therapy. Results were not affected by severity of illness, or by excluding patients who died within 2 days of admission. Identified predictors of death in a multivariate regression model were age >65 years (OR=2.6), two or more lung lobes affected (OR=2.2), and severity of disease as estimated using the acute physiology score (APS)>8.

Adult↗

Fuzzy polynucleotide spaces and metrics.

The study of genetic sequences is of great importance in biology and medicine. Mathematics is playing an important role in the study of genetic sequences and, generally, in bioinformatics. In this paper, we extend the work concerning the Fuzzy Polynucleotide Space (FPS) introduced in Torres, A., Nieto, J.J., 2003. The fuzzy polynucleotide Space: Basic properties. Bioinformatics 19(5); 587-592 and Nieto, J.J., Torres, A., Vazquez-Trasande, M.M. 2003. A metric space to study differences between polynucleotides. Appl. Math. Lett. 27:1289-1294: by studying distances between nucleotides and some complete genomes using several metrics. We also present new results concerning the notions of similarity, difference and equality between polynucleotides. The results are encouraging since they demonstrate how the notions of distance and similarity between polynucleotides in the FPS can be employed in the analysis of genetic material.

Algorithms↗

Donor age and degree of HLA matching have a major impact on the outcome of unrelated donor haematopoietic cell transplantation for chronic myeloid leukaemia.

We analysed the outcome of 92 consecutive unrelated donor haematopoietic cell transplantations (UD-HCTs) performed in Spain to treat adult patients with CML in the first chronic phase (1CP). Patients' and donors' median age was 32 (15-49) and 36 (22-56) years, respectively. In all, 73 pairs (79%) matched for A, B+/-C and DRB1+/-DQB1 loci and 19 had > or =1 mismatch. Their probability of survival and disease-free survival at 4 years were 50 and 46%, respectively. Pretransplant factors associated with a better survival were patient age <25 years (P=0.035), donor age < or =36 years (P=0.012), use of cyclosporine since day -7 (P=0.001), and matching 8/8, 9/10 or 10/10 loci at allele level (P=0.003). In multivariate analysis only donor age (P=0.003; RR=3.1 (95% CI: 1.3-7.1)) and degree of HLA-matching (P=0.009; RR: 7.7 (95% CI: 1.8-33)) maintained their significance. The addition of these two variables to the EBMT prognostic score allowed an adequate risk assessment for patients receiving a UD-HCT during 1CP. Our analysis shows that in patients with a young and fully allele-matched donor, UD-HCT should be considered in the initial therapeutic algorithm due to its excellent outcome (92% survival at 2 years).

Adolescent↗

Genetic diversity in Aspergillus parasiticus population from the peanut agroecosystem in Argentina.

AIMS: The aims of this work were to identify potential sources of Aspergillus parasiticus inoculum and to evaluate the sclerotial and toxigenic profiles of this species from the peanut agroecosystem in Argentina. Likewise, the genetic diversity of A. parasiticus population was analysed using vegetative compatibility group (VCG) analysis. METHODS AND RESULTS: The A. parasiticus strains were isolated from soil, debris and peanut seeds in Córdoba Province, Argentina. A. parasiticus was recovered from the three sources analysed. Only 11 of 185 A. parasiticus isolates (5.9%) did not produce aflatoxins, while 57% produced sclerotia. Twenty-four VCG were identified from 63 isolates. The VCG diversity index for A. parasiticus, expressed as the number of groups divided by the total number of isolates, was 0.31. In general, there were significant differences among VCG in aflatoxin production. CONCLUSIONS: The presence of aflatoxigenic strains of A. parasiticus in the three substrates suggests that they may be an important source of aflatoxin in Argentina's peanut agroecosystem. The A. parasiticus population shows a low genetic diversity. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study showed data on inoculum distribution, aflatoxin and sclerotia production and genetic diversity in an A. parasiticus population isolated from the peanut agroecosystem in Argentina.

Aflatoxins↗

Mixed community-acquired pneumonia in hospitalised patients.

The role of mixed community-acquired pneumonia (CAP) is controversial. The aim of the present study was to determine the incidence, principal microbial patterns, clinical predictors and course of mixed CAP. The current study included 1,511 consecutive hospitalised patients with CAP. Of these, 610 (40%) patients had an established aetiology. One pathogen was demonstrated in 528 patients and 82 (13%) patients had mixed pneumonia. Cases including CAP, by a pyogenic bacteria and a complete paired serology for "atypicals", revealed that 82 (13%) patients had definite single pyogenic pneumonia and 28 patients (5%) had mixed pyogenic pneumonia. In patients with mixed CAP, Streptococcus pneumoniae was the most prevalent microorganism (44 out of 82; 54%). The most frequent combination was S. pneumoniae with Haemophilus influenzae (17 out of 82; 21%). Influenza virus A and S. pneumoniae (five out of 28; 18%) was the most frequent association in the mixed pyogenic pneumonia group. No clinical predictors for mixed pneumonias could be identified. Patients with mixed pyogenic pneumonia more frequently developed shock when compared with patients with single pyogenic pneumonia (18 versus 4%). In conclusion, mixed pneumonia occurs in >10% of cases with community-acquired pneumonia requiring hospitalisation.

Adolescent↗

Intracranial retrograde dissemination in filum terminale myxopapillary ependymomas.

Myxopapillary ependymomas (ME) are considered benign tumours (WHO grade I) of the central nervous system with long term survival rates and a tendency to local recurrence. However an aggressive course has occasionally been described, leading to CSF dissemination and even systemic metastases. We describe the case of a 23-year-old man diagnosed with intracranial subarachnoid dissemination of a filum terminale ME three years after the initial diagnosis. We have performed a careful review of the literature on CSF dissemination in ME and finally propose treatment of these cases.

Adult↗