Flagella-specific proteins of Leishmania have been identified employing the monoclonal antibody technique. Six monoclonal antibodies recognized 3 different proteins. A doublet of protein of Mr 69,000 and 74,000 Da identified by monoclonal antibodies F-3, F-4 and F-6 is continuously distributed along the flagellum by immunofluorescence. Immunocytochemical electron microscopic studies localize these molecules to the paraxial rod of the flagellum. A single protein of Mr 13,200 Da is recognized by monoclonal antibodies F-1, F-2 and F-5. The distribution of the Mr 13,200 protein appears irregular, occurring in localized patches along the length of the flagellum, especially at the flagellar tip. Immunocytochemical electron microscopic experiments show that the Mr 13,200 molecule is associated with the membrane of the flagellum. Indirect immunofluorescence experiments demonstrated these monoclonal antibodies cross-reacted with members of the Kinetoplastida family (Endotrypanum, trypanosoma, Leishmania) suggesting that these molecules may be evolutionarily conserved.

Restriction endonuclease DNA fragment patterns have been used to examine the relationships among 28 isolates of Leishmania as well as Crithidia, Endotrypanum, and Trypanosoma cruzi. Fragments of nuclear DNA were generated with six restriction enzymes, and blots were hybridized with probes from three loci. Among the major lineages the fragment patterns are essentially completely different, while within the major lineages various degrees of divergence are found. Molecular evolutionary trees were constructed using the method of Nei and Li to estimate the percent nucleotide sequence divergence among strains from the fraction of fragments shared.Defined groups, such as species or subspecies within the major lineages, are also grouped by nuclear DNA comparisons. Within the donovani complex, we find Leishmania donovani chagasi and Leishmania donovani infantum to be as similar as strains within Leishmania donovani donovani, consistent with the proposal by other workers that New World visceral leishmaniasis originated quite recently.Protozoans belonging to the genus Leishmania are frequently parasites in humans, causing a spectrum of diseases whose severity ranges from mild through severely disfiguring to lethal (1). A variety of clinical, biological, and geographical criteria were initially used to classify species (1). With further study it became evident that geographical and pathological criteria were often inadequate to discriminate among different isolates, and biochemical and molecular approaches were employed, including comparisons of isoenzymes (2-5), kinetoplast DNA (6-9), proteins (10), and antigens (11)(12)(13)(14) Comparisons of nuclear DNA have been successfully employed in other organisms for the estimation of temporal and cladistic relationships of species (18)(19)(20). We used Southern blot hybridization with various defined nuclear DNA probes to obtain data that was analyzed by the method of Nei and Li (21) to estimate first the fraction of DNA fragments shared among species and then the percent of nucleotide sequence divergence. This method yields results that generally agree with comparisons of DNA sequences or of other parameters (refs. 20,22,and 23; personal communication). However, the calculation of percent divergence assumes that all fragment differences are attributable to point mutations. This assumption may not always be valid for nuclear DNA, where the presence of detectable length mutations would lower the fraction of fragments shared between two species and thus inflate the estimate of sequence divergence (24). To detect any anomalies caused by length mutations, we examined three independent regions of the nuclear genome and analyzed each data set separately as well as in combination. Our analysis indicates that the fragment comparison method is indeed suitable for comparisons within the major lineages of Leishmania.

Evidence‐based medicine (EBM) is the rubric for an approach to learning and practicing medicine that applies skills from clinical epidemiology, library science, and information management to clinical practice. Teaching EBM effectively requires a longitudinal approach throughout medical education. This presents many opportunities for academic emergency physicians, especially in the setting of an emergency medicine clerkship. EBM is best taught at the bedside, although this depends on a skilled and interested faculty. Bedside teaching of EBM also requires ready access to modern information resources. Other venues for teaching EBM include morning report, teaching conferences, and journal clubs. Many tools can be used to aid the process, including Web‐based sources such as UpToDate, textbooks, and Web‐based tutorials, educational prescriptions, and critically appraised topics.

Evidence-based medicine (EBM) is the rubric for an approach to learning and practicing medicine that applies skills from clinical epidemiology, library science, and information management to clinical practice. Teaching EBM effectively requires a longitudinal approach throughout medical education. This presents many opportunities for academic emergency physicians, especially in the setting of an emergency medicine clerkship. EBM is best taught at the bedside, although this depends on a skilled and interested faculty. Bedside teaching of EBM also requires ready access to modern information resources. Other venues for teaching EBM include morning report, teaching conferences, and journal clubs. Many tools can be used to aid the process, including Web-based sources such as UpToDate, textbooks, and Web-based tutorials, educational prescriptions, and critically appraised topics.

No abstract