Behavior in a mouse model of isolates of Leishmania donovani sensu lato cultured from the blood of patients with chronic cutaneous lesions.

Our objective was to characterize biologically in an animal model two isolates of Leishmania parasites unexpectedly encountered in the circulating blood of two patients with chronic cutaneous leishmaniasis. Both isolates were classified by cellulose acetate electrophoresis as belonging to the L. donovani senso lato complex. We elected to use BALB/c mice, an inbred strain that has been proven to be very sensitive to the dermotropic parasite L. major. This study demonstrated that for the same number of parasites, the course of infection with the L. donovani strain was different from that developed in similar animals that received the L. major strain. After a protracted incubation period, L. donovani produced scanty cutaneous lesions and mainly a systemic disease. This is in contrast to the rapidly spreading skin lesion that kills L. major-infected animals within a few months. It is concluded that BALB/c mice are an adequate animal model for the L. donovani strain, which had an unusual clinical presentation in humans. The prolonged incubation period, such as observed here, may lead to erroneous conclusions of host resistance if the experiment were terminated based on L. major activity in the same model. Finally, the unusual behavior in humans and mice of certain strains (such as the one encountered in these patients) must reflect peculiar intrinsic features of the parasite, which are best understood using animal models in the laboratory.

[Impact of electric cardiac stimulation on ventricular function and the natural history of patients with myocardiopathy]. / Impacto de la estimulación cardíaca eléctrica sobre la función ventricular y la historia natural de los pacientes con miocardiopatía.

There has recently been an increasing interest in beneficial effects of cardiac pacing in patients with myocardial diseases, especially in Obstructive Hypertrophic and Dilated Cardiomyopathy. The experience with dual-chamber pacing for obstructive hypertrophic cardiomyopathy is now important. DDD pacing for sinus rhythm patients and VVI pacing in patients with atrial fibrillation have shown considerable symptomatic improvement, with a significant decrease of angina, dyspnea, presyncope and frank syncope. It has been suggested that DDD pacing may prevent sudden death and improve survival rates in these patients, but this has not yet been established. The experience with DDD pacing in dilated cardiomyopathy is more limited, but in specially chosen patients, DDD pacing with short AV delay has shown symptomatic improvement and a decrease in the need for further hospitalization due to worsening of heart failure. There is no current evidence of higher survival rates with this treatment, but DDD pacing may be used in patients with end-stage dilated and isquemic cardiomyopathy who are waiting for a heart transplantation.

New technique for right heart catheterization using a Mullins' sheath.

A new technique for right heart catheterization using a Mullins' sheath is described. This device allows a Swan-Ganz catheter to reach pulmonary artery position easily and permits simultaneous pressure recordings in right heart chambers, thus avoiding a double venous puncture and two catheters. This new technique, its indications, and our experience in 29 patients are described. It is most useful in patients with severe pulmonary hypertension and in those conditions in which accurate right heart pressure measurements are needed.