Tratamiento antitrombótico en la fibrilación auricular no reumática. ¿Cumplimos las recomendaciones de los ensayos clínicos? / Antithrombotic treatment in nonrheumatic atrial fibrilation: do we follow clinical trial recomendations?

Objetivos: Distintos ensayos clínicos han demostrado que el tratamiento antitrombótico puede ser eficaz en la prevención del ictus en pacientes con fibrilación auricular (FA) no reumática. El objetivo del presente estudio fue conocer si se cumplen las recomendaciones de los grandes ensayos clínicos en la práctica clínica y, valorar los factores que pueden influir en la decisión del distinto tratamiento antitrombótico empleado. Métodos: Analizamos la historia clínica de 225 pacientes diagnosticados de FA no reumática en Cáceres durante los meses de Febrero y Marzo de 1998. Se excluyeron 20 pacientes por contraindicación para mantener tratamiento antitrombótico o, sin evidencia de FA crónica, por lo que finalmente 205 enfermos formaron parte del estudio. Se compararon los pacientes que seguían tratamiento antitrombótico (anticoagulante o antiagregante) y sin tratamiento, con distintas características demográficas y factores de riesgo embolígeno. Resultados: De los 205 enfermos que formaron parte del estudio, 149 (72,6%) tenían un riesgo embolígeno elevado. Sesenta y dos pacientes (30,2%) del total seguían tratamiento con anticoagulantes, 94 (45,8%) antiagregantes, 5 (2,4%) doble tratamiento y 49 (24%) no realizaban ningún tipo de tratamiento. No hubo diferencias entre el grupo de pacientes con tratamiento anticoagulante, antiagregante o sin tratamiento respecto a la edad, sexo, presencia de cardiopatía isquémica, hipertensión arterial e insuficiencia cardiaca en los últimos 3 meses, mientras que, el antecedente de accidente cerebrovascular y otras variables ecocardiográficas (valvulopatía, calcificación valvular, disfunción ventricular) fueron mas frecuentes en los pacientes anticoagulados y antiagregados, que en aquellos sin tratamiento. Conclusiones: Un alto porcentaje de pacientes con FA no reumática sigue algún tipo de tratamiento preventivo antitrombótico, aunque posiblemente todavía un gran número de enfermos con FA podría beneficiarse del tratamiento anticoagulante. En nuestro medio, la valoración terapéutica de los enfermos con FA crónica debería tener en cuenta, además de hallazgos ecocardiográficos, otras características clínicas, como hipertensión arterial, cardiopatía isquémica e insuficiencia cardiaca (AU)

Correlation between the affinity of flavonoids binding to the cytosolic site of Leishmania tropica multidrug transporter and their efficiency to revert parasite resistance to daunomycin.

The C-terminal nucleotide-binding domain (NBD2) of a P-glycoprotein-like transporter, encoded by the ltrmdr1 gene in Leishmania tropica and involved in parasite multidrug resistance (MDR), was overexpressed in Escherichia coli as a hexahistidine tagged protein and purified. The L. tropica recombinant domain efficiently bound fluorescent derivatives of ATP, the hydrophobic steroid analogue RU 486, and different classes of flavonoids with the following efficiency: flavone > flavanone > isoflavone > glucorhamnosyl-flavone > chromone. The affinity for flavones was dependent on the presence of hydroxyl groups at positions 5 and 3 and was further increased by a hydrophobic 1,1-dimethylallyl substituent at position 8. When flow cytometry was used to measure daunomycin accumulation in a MDR L. tropica line, a reversing effect was observed with flavones such as dimethylallyl-kaempferide at low concentration or apigenin at higher concentration, but neither with the glucorhamnosyl derivative rutin nor with the isoflavone genistein. The in vivo reversing effect of dimethylallyl-kaempferide was correlated to a high inhibition of MDR cell growth in the presence of daunomycin. The results suggest that flavone inhibition of both daunomycin efflux and parasite growth in the presence of the drug correlates to direct binding of the compound to cytosolic domain of the P-glycoprotein-like transporter.

[Antithrombotic treatment in non-rheumatic atrial fibrillation. Do we follow the recommendations of clinical trials?]. / Tratamiento antitrombótico en la fibrilación auricular no reumática. Cumplimos las recomendaciones de los ensayos clínicos?

OBJECTIVES: Several clinical trials have demonstrated that antithrombotic treatment may be effective in prevention of stroke in nonrheumatic atrial fibrillation (AF). The aim of this study was to assess if we follow clinical trial recommendations in community practice. METHODS: We analyzed 225 medical records of patients diagnosed of nonrheumatic AF in Cáceres, during February and March 1998. Patients who were contraindicated to follow antiagreggation or anti-coagulation treatment were excluded. We compared patients with and without antithrombotic treatment with different demographic characteristics and embolic risk factors. RESULTS: 205 patients were included in the study, 149 (72.6%) had high embolic risk. 62 (30.2%) followed anticoagulation, 94 (45.8%) antiaggregation treatment, 5 (2.4%) both treatment and 49 (24%) were not receiving therapy. We didn't findings differences between age, sex, presence of ischemic heart disease, hypertension and congestive heart failure in last three months compared with the patients in respect to the group of patients with anticoagulation and antiaggregation therapy or without it. We determinate as well that previous stroke and echocardiographical finds (valve disease, valve calcification, ventricular dysfunction) were more frequent in the anticoagulation and antiaggregate patients than in those without therapy. CONCLUSION: A high range of nonrheumatic AF patients take any kind of antithrombotic preventive therapy, though a great number of patients with high embolic risk could still get benefits from anticoagulation therapy. We should considerate in the therapy assessment some other clinical characteristics as hypertension, isquemic heart disease and heart failure apart from echocardiographical findings.

Altered drug membrane permeability in a multidrug-resistant Leishmania tropica line.

We selected a Leishmania tropica cell line resistant to daunomycin (DNM) that presents a multidrug-resistant (MDR) phenotype characterized by overexpression of a P-glycoprotein of 150 kDa. The resistant line overexpressed an MDR-like gene, called ltrmdr1, located in an extrachromosomal circular DNA. DNM uptake experiments using laser flow cytometry showed a significant reduction in drug accumulation in the resistant parasites. The initial stages of the interaction of DNM with membranes from wild-type and DNM-resistant parasites were defined by a rapid kinetic stopped-flow procedure which can be described by two kinetic components. On the basis of a previous similar kinetic study with tumor cells, we ascribed the fast component to rapid interaction of DNM with membrane surface components and the slow component to passive diffusion of the drug across the membranes. The results reported here indicate that entrance of DNM into wild-type parasites was facilitated in respect to the resistant ones. We propose that resistance to DNM in L. tropica is a multifactorial event involving at least two complementary mechanisms. an altered drug membrane permeability and the overexpression of a protein related to P-glycoprotein that regulates drug efflux.

[Chlamydia psittaci and Chlamydia pneumoniae infection in Caceres]. / Infección por Chlamydia psittaci y pneumoniae en Cáceres.

OBJECTIVE: The study of the clinical and epidemiological characteristics of infectious process caused by Chlamydia pneumoniae and Chlamydia psittaci in our medium, Cáceres. METHOD: We are reviewed retrospectively clinical aspects of the patients with infections due to Chlamydia in the las five years. We accepted patients with compatible symptoms and serologic demonstration of recent infection with conventional complement fixation and/or microimmunofluorescence assay, the last used to distinguish Chlamydia pneumoniae. RESULTS: We are studied sixteen patients (9 males and 7 females), sixth median age 46.6 (26-70). Fifteen patients was diagnosed in winter. We found five cases of Chlamydia pneumoniae and three of Chlamydia psittaci. In the other eight cases we didn't distinguish between Chlamydia pneumoniae and Chlamydia psittaci. All patients had fever, accompanied by lung symptoms and pulmonary infiltrates in the 75% of them. The most frequent clinical information was the discord between the pulse and temperature (81%). Splenomegaly was observed in three patients (19%) being the diagnosis of them psitacosis. Nine patients had respiratory insufficiency and eight (50%) disturbance in hepatic enzymes. The clinical presentation in one patients was as unknown origin fever. CONCLUSIONS: The infection produced by Chlamydia in the hospitalary medium isn't much diagnosed in our unit. The months of winter favour the infection. We think that splenomegaly is the only different characteristic in these infections, suggesting psitacosis.

Amplification of the H locus in Leishmania infantum.

We have selected for a Leishmania infantum cell line resistant to high levels of methotrexate (MTX). The resulting cells were 1233-fold more resistant than wild-type and contained amplified H-region circles. Homologous genes to the antifolate resistant ltdh gene and to the P-glycoprotein ltpgpA gene of Leishmania tarentolae were observed to be contained within the amplicon. In order to invoke additional mechanisms of resistance, we examined possible variations in MTX accumulation. Resistance was not correlated with a decreased uptake of MTX. On the contrary, the resistant line presented a 3-fold increase in the steady-state accumulation of drug with regard to the wild-type line. Northern blot analysis using gene specific probes, showed that the ltdh probe and the ltpgpA probe recognized single transcripts of 1 kb and 5 kb respectively which were both overexpressed only approx. 5-fold in resistant cells. We propose that amplification of the antifolate resistance gene, homologue to the ltdh gene of L. tarentolae, is apparently the only mechanism involved in resistance to the cytotoxic drug MTX in L. infantum resistant to 1000 microM of MTX.

P-glycoprotein overexpression in methotrexate-resistant Leishmania tropica.

A methotrexate (MTX)-resistant Leishmania tropica line develops a stable drug-resistant phenotype in which the resistance mechanism is associated with a significant reduction in MTX accumulation. After a 2 hr exposure to [3H]MTX, a L. tropica line resistant to 1000 microM of MTX did not accumulate more than 3% of the amount of drug incorporated by wild-type cells. The same resistant cell line was found to be cross-resistant to several unrelated drugs. The monoclonal antibody C219, directed against the cytoplasmic domain of mammalian P-glycoproteins, recognized a putative P-glycoprotein of 240 kDa overexpressed in the resistant line. Also, this resistant line showed the overexpression of the putative homolog of the ltpgpE gene, as determined by northern blot analysis using gene-specific probes for the P-glycoprotein genes of Leishmania tarentolae. This overexpression was not correlated with a proportional increase in the copy number of the gene, but Southern blot analysis suggested that the ltpgpE homolog was overexpressed as a consequence of gene rearrangement. This would be considered as an epiphenomenon that probably does not arise from the same MTX-resistant mechanism.