More on malaria mortality in the Pacific.
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Adolescent↗
Biomedical subjects
P Bastien
Publications and source records attributed to P Bastien.
Genetic nomenclature for Trypanosoma and Leishmania.
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Animals↗
Conserved linkage groups associated with large-scale chromosomal rearrangements between Old World and New World Leishmania genomes.
The genus Leishmania can be taxonomically separated into three main groups: the Old World subgenus L. (Leishmania), the New World subgenus L. (Leishmania) and the New World subgenus L. (Viannia). The haploid genome of Old World Leishmania species has been shown to contain 36 chromosomes defined as physical linkage groups; the latter were found entirely conserved across species. In the present study, we tried to verify whether this conservation of the genome structure extends to the New World species of Leishmania. 300 loci were explored by hybridization on optimized pulsed field gel electrophoresis separations of the chromosomes of polymorphic strains of the six main pathogenic Leishmania species of the New World. When comparing these New World karyotypes with their Old World counterparts, 32 out of 36 linkage groups were found conserved among all species. Four chromosomal rearrangements were found. All species belonging to the L. (Viannia) subgenus were characterized by the presence (i) of a short sequence exchange between chromosomes 26 and 35, and (ii) more importantly, of a fused version of chromosomes 20 and 34 which are separated in all Old World species. 69 additional markers were isolated from a plasmid library specifically constructed from the rearranged chromosomes 20+34 in an attempt to detect mechanisms other than a fusion or breakage: only two markers out of 40 did not belong to the linkage groups 20 and 34. On the other hand, all strains belonging to the New World subgenus L. (Leishmania) were characterized by two different chromosomal rearrangements of the same type (fusion/breakage) as above as compared with Old World species: chromosomes 8+29 and 20+36. Consequently, these two groups of species have 35 and 34 heterologous chromosomes, respectively. Overall, these results show that large-scale chromosomal rearrangements occurred during the evolution of the genus Leishmania, and that the three main groups of pathogenic species are characterized by different chromosome numbers. Nevertheless, translocations seem particularly rare, and the conservation of the major linkage groups should be an essential feature for the compared genetics between species of this parasite.
Animals↗
The complete chromosomal organization of the reference strain of the Leishmania Genome Project, L. major ;Friedlin'.
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Journal Article↗
Haemoculture as a tool for diagnosing visceral leishmaniasis in HIV-negative and HIV-positive patients: interest for parasite identification.
Between May 1993 and June 1996, 65 adults infected with human immunodeficiency virus (HIV) and 30 HIV-negative patients (8 children and 22 adults) from the Mediterranean region with symptoms that included at least fever were examined for Leishmania. A total of 128 bone marrow and 128 peripheral venous blood samples were taken and cultured on NNN medium. At the initial diagnosis, 14 (6 HIV-positive and 8 HIV-negative) of 15 patients with a positive blood culture also had a positive bone marrow culture. Two patients (1 HIV-positive and the other HIV-negative) had a positive bone marrow culture but a negative blood culture. During post-therapeutic check-ups, 7 out of 8 patients with a positive blood culture (6 HIV-positive and 1 HIV-negative) also had a positive bone marrow culture. On the other hand, three patients (2 HIV-positive and 1 HIV-negative) had a positive bone marrow but a negative blood culture. Relapses were more frequent (9/65 vs. 3/30) and the demonstration of Leishmania in the blood was commoner (6/65 vs. 2/30) in the HIV-positive than the HIV-negative patients. Stocks were identified by their isoenzymes: MON-1 from four HIV-positive and eight HIV-negative patients, MON-28 from one HIV-positive patient and MON-29 from another. For each patient, the same zymodeme was found in bone marrow and blood cultures, both at initial diagnosis and at follow-up.
AIDS-Related Opportunistic Infections↗
A direct method for the chromosomal assignment of DNA markers in Leishmania.
A simple method for the chromosomal assignment of any DNA marker would be an important tool for the ongoing project to map the genome of the protozoan parasite Leishmania. The Leishmania chromosomes enter pulsed field gel electrophoresis (PFGE) gels under current electrophoretic conditions, but their direct identification in a given strain is hampered by their stacking in a few chromosomal bands, and by the very frequent size variations of the same chromosome among parasite strains. To overcome these problems. we determined the complete karyotypes of 12 Old World Leishmania cloned strains. This enabled us to select three of these strains that display great chromosome size polymorphisms, such that every chromosome can be individualized by a specific pattern after hybridization onto these three karyotypes. The complete resolution of the genomes of these three strains can be carried out with only three electrophoretic conditions. This makes a series of three blots sufficient for the assignment of any new marker on a particular Leishmania chromosome.
Animals↗
[Dirofilariasis in France: a case in Languedoc in an HIV-seropositive patient].
Dirofilaria repens is an endemic canine parasite in the Mediterranean area. Human infestation is rare. We observed a case in an HIV-positive patient who presented an ocular filaria which was successfully removed under local anesthesia. In man, filariae may be expulsed without a parasite cycle or complete a growth cycle, depending on the individual's immunological status. The disease has been known in southern France for several centuries, mainly in lagoons near the Mediterranean seaside. A review of the literature however shows that observation of clinical cases is rare, only 46 cases having been reported to date. Outcome is favorable.
Adult↗
Medium-range restriction maps of five chromosomes of Leishmania infantum and localization of size-variable regions.
The chromosomes of the human protozoan parasite Leishmania exhibit striking size polymorphisms among different strains. To define the structural basis for these variations, we have constructed full-length restriction maps of five chromosomes of 370 to 490 kb in Leishmania infantum clone LEM1317. Rare-cutting sites for the enzymes AseI, DraI, XbaI, SspI, SpeI, and SfiI were mapped by partial and complete digestion of either gel-purified chromosomes or total DNA. Sixty-eight anonymous DNA probes were localized on these maps, as well as the mini-exon and dihydrofolate reductase-thymidilate synthase gene probes. These maps were compared with those from other strains of L. infantum and Leishmania donovani. This showed that the distribution of the restriction sites was conserved in these two close species. Four regions involved in the size variations of three chromosomes were localized; subtelomeric sequences were responsible for size variability in three of four cases. The whole of this study takes a particular significance in the frame of the project of complete physical mapping and sequencing of the Leishmania genome.
Animals↗
The Leishmania genome comprises 36 chromosomes conserved across widely divergent human pathogenic species.
All the physical linkage groups constituting the genome of Leishmania infantum have been identified for the first time by hybridization of specific DNA probes to pulsed field gradient-separated chromosomes. The numerous co-migrating chromosomes were individualised using the distinctive size polymorphisms which occur among strains of the L. infantum/L. donovani complex as a tool. A total of 244 probes, consisting of 41 known genes, 66 expressed sequence tags (ESTs) and 137 anonymous DNA sequences, were assigned to a specific linkage group. We show that this genome comprises 36 chromosomes ranging in size from 0.35 to -3 Mb. This information enabled us to compare the genome structure of L. infantum with those of the three other main Leishmania species that infect man in the Old World, L. major, L. tropica and L. aethiopica. The linkage groups were consistently conserved in all species examined. This result is in striking contrast to the large genetic distances that separate these species and suggests that conservation of the chromosome structure may be critical for this human pathogen. Finally, the high density of markers obtained during the present study (with a mean of 1 marker/130 kb) will speed up the construction of a detailed physical map that would facilitate the genetic analysis of this parasite, for which no classical genetics is available.
Animals↗
Conservation among Old World Leishmania species of six physical linkage groups defined in Leishmania infantum small chromosomes.
We have characterised 49 DNA probes specific for each of the six smallest chromosomes in Leishmania infantum and have examined the allocation of these probes in the molecular karyotypes of the other Old World Leishmania species Leishmania donovani, Leishmania major, Leishmania tropica and Leishmania aethiopica. These 49 probes define 6 physical linkage groups in the molecular karyotypes of various strains of L. infantum. 40 of these probes hybridise in the other Old World Leishmania species and show a remarkably conserved linkage pattern. No interchromosomal exchange nor fusion could be detected. Thus, in spite of the chromosomal size polymorphisms, the general structure of the genome seems to be conserved in the six smallest chromosomes among Old World Leishmania species. This structural genomic homogeneity should be helpful for mapping studies of any Old World Leishmania genomes.
Animals↗
A polymorphic minisatellite sequence in the subtelomeric regions of chromosomes I and V in Leishmania infantum.
A minisatellite DNA sequence is described for the first time in Leishmania infantum. It is borne by four chromosomes and consists of an 81-bp repeat unit organised in several clusters. On chromosomes I and V of L. infantum, the clusters are tightly located in the size-variable subtelomeric regions. The organisation of this sequence may be related to that of the subtelomeric interspersed repeat sequences identified in the human genome. The sequencing of seven repeat units, some subcloned from the same cluster, allowed the definition of a consensus sequence of 81 bp, particularly G/C rich (73%). Two subfamilies were clearly defined: one exhibits a 91-95% homology with the consensus sequence; the second one comprises two monomers sharing a 91% homology but only 77% homology with the consensus sequence. The two types of monomers can be found in the same cluster. These data suggest interactions between monomers and a possible role of this sequence in the instability of these regions. Finally, restriction fragment length polymorphisms were revealed by this sequence among various strains of L. infantum. Besides allowing the detection of recombination events in the unstable regions of the chromosomes, this new marker may become a useful tool in the study of the parasite population dynamics in leishmaniasis foci.
Animals↗
[Heterophyiasis and diarrhea after travel: a case report of a child returning from a trip to Egypt].
The most frequently reported parasite-related diarrheal diseases in tropical travellers are amibiaisis, giardiasis, and certain types of nematoodiasis. Intestinal distomiasis is uncommon because the parasite is strictly limited to certain areas of the world. However observation is possible as is demonstrated by this case report involving a 3-year-old child who presented diarrhea two weeks after returning from a six-week stay Egypt. Heterophyes heterophyes eggs were identified. This small fluke has only exceptionally been reported in France where no indigenous case has ever been described. The present report provides an opportunity to review the clinical symptoms and epidemiology of this rare distomiasis, found only in south-east Asia and Egypt. Comparison of egg morphology allowed diagnosis of hysterophiasis by differentiation from smaller fluke species (Clonorchis and Opistorchis). The authors of this report emphasize that this is a rare but possible cause of diarrhea in travellers.
Animals↗
Structural organisation of microsatellite families in the Leishmania genome and polymorphisms at two (CA)n loci.
In the present study, we have analysed the frequency and distribution of several microsatellite DNAs [(CA)n, (GGT)n and (GCA)n] in the genome of Leishmania. Hybridisation analysis on the molecular karyotypes of different Leishmania strains showed the presence of these three microsatellites on all chromosomes of the parasite. The number of microsatellite clusters appeared grossly similar among strains from different Old World complexes. However, these three microsatellite families showed an uneven distribution among heterologous chromosomes of the same strain. Moreover, restriction analysis of chromosome I in various strains of Leishmania infantum showed a strong clustering of these microsatellites in the same chromosomal region. A partial genomic library was screened with a (CA)n probe, and 21 positive clones were isolated. The sequencing of these clones confirmed the association of various microsatellites such as (CA)n, (CT)n, and (GCA)n. Finally, specific polymerase chain reaction amplification of two cloned (CA)n loci demonstrated allelic size polymorphisms among strains within L. infantum and Leishmania donovani. Most of the 34 strains analysed were found to be monoallelic, while two alleles were found in a small number of strains. The interest of these sequences for studies on ploidy and population genetics of the parasite is discussed.
Animals↗
[Changes in plasma atrial natriuretic factor, plasma and urinary cyclic GMP during exercise in coronary patients and healthy subjects].
The concentrations of plasma ANF and plasma and urinary cyclic GMP were measured at rest and during exercise in 12 normal subjects (reference group) and 20 patients with coronary artery disease (coronary group). In both groups, plasma ANF and c GMP increased during exercise and fell one hour after (F = 3.8, p = 0.029 and F = 13.3, p = 0.0001, respectively) whereas the urinary c GMP increased one hour after exercise (F = 5.3, p = 0.029). In the control group, ANF increased on effort and fell during recovery to above its resting value whereas the plasma c GMP remained unchanged throughout the test. In the coronary group, no significant increase in ANF was observed on effort (wide dispersion of values) whereas the c GMP increased during effort and fell to below testing value during the recovery phase. The ANF of the coronary group was globally higher than the ANF of the control group (F = 4.7, p = 0.04). The plasma c GMP of the coronary group was comparable to that of the controls (F = 2.1, p = 0.15) despite higher concentrations at rest (p < 0.05) and during exercise (p < 0.05). However, there was a positive interaction between the efforts of exercise and the pressure of coronary disease on the concentration of plasma c GMP (F = 6.7, p = 0.0024). There was no difference in urinary c GMP between control and coronary subjects (F = 1, p = 0.33).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Molecular karyotype analysis in Leishmania.
The advent of pulsed field electrophoresis has allowed a direct approach to the karyotype of Leishmania. The molecular karyotype thus obtained is a stable characteristic of a given strain, although minor modifications may occur during in vitro maintenance. Between 20 and 28 chromosomal bands can be resolved depending on the strain, ranging in size from approximately 250 to 2600 kb. The technique has revealed a striking degree of polymorphism in the size and number of the chromosomal bands between different strains, and this seems independent of the category (species, zymodeme, population) to which the strains belong. It appears that only certain strains originating from the same geographic area may share extensive similarities. This polymorphism can largely be accounted for by chromosome size variations, which can involve up to 25% of the chromosome length. As a result, homologous chromosomes can exist in versions of markedly different size within the same strain. When this occurs with several different chromosomes, the interpretation of PFE patterns appears difficult without prior identification of the size-variable chromosomes and of the chromosome homologies. DNA deletions and amplifications have been shown to account for some of these size modifications, but other mechanisms are probably involved; nevertheless, interchromosomal exchange does not seem to play a major role in these polymorphisms. These chromosomal rearrangements, yet in an early stage of characterization, exhibit two relevant features: they seem (1) to affect essentially the subtelomeric regions and (2) to occur in a recurrent nonrandom manner. Chromosomal rearrangements sharing the same characteristics have been identified in yeast and other protozoa such as Trypanosoma and Plasmodium. The significance of this hypervariability for the biology of the parasite remains unknown, but it can be expected that such mechanisms have been maintained for some purpose; genes specifically located near chromosome ends might benefit from rapid sequence change, alternating activation, or polymorphism of expression. The chromosomal plasticity could represent a general mode of mutation in these parasites, in parallel with genetic exchange which may be uncommon in nature. The molecular characterization of these rearrangements, the identification of each chromosome with the help of physical restriction maps and linkage maps, and the collation of such data on a number of strains and species should allow a significant progress in the understanding of the genetics of Leishmania, in particular as regards ploidy, generation of phenotypic diversity, and genome evolution. Finally, like other models, this is susceptible to improve our knowledge of DNA-DNA interactions and of the chromosome functional structure and dynamics.
Animals↗
Leishmania tropica infection in hamsters and a review of the animal pathogenicity of this species.
Four strains of Leishmania tropica s. st. from Afghanistan were found to be constantly infective to the golden hamster (Mesocricetus auratus), whether inoculated as culture promastigotes from early passages or as amastigotes from the cutaneous lesions. In total, 66 amastigote passages were carried out over 6 passage generations. The footpad lesions were chronic and nonulcerative infiltrates; their evolution is described up to 15 months. No self-healing was observed. Balb/c mice and gerbils were not susceptible. Earlier studies on L. tropica s. st. in laboratory animals, principally by Soviet and French workers, are critically reviewed. This new experimental model of chronic cutaneous leishmaniasis is of special interest for studies on the immunology and chemotherapy of the disease. Some advantages over the commonly used L. major model are discussed.
Animals↗
Multiple forms of chromosome I, II and V in a restricted population of Leishmania infantum contrasting with monomorphism in individual strains suggest haploidy or automixy.
We have resolved the molecular karyotypes of 22 Leishmania infantum strains isolated between 1980 and 1988 in a restricted geographic area and belonging to zymodemes MON-11, -29 and -33. Three strains were isolated from sandflies and all the others from human cutaneous lesions. A high degree of karyotypic homology is observed among these strains, contrasting with the highly polymorphic MON-1 strains isolated in the same area. We have analysed the time-dependent evolution of size variants of chromosomes I to V, each identified by chromosome-specific DNA probes. More evidence is given for the role of subtelomeric regions in chromosomal size variation in Leishmania for both chromosomes I and II. At the population level, the chromosomes I, II and V are present in respectively 8, 4 and 3 distinct sizes. Furthermore, and despite the small size of the sample, various combinations were observed among these different chromosomal forms. These results could be explained by the occurrence of a high rate of recurrent mutations or of genetic exchange. In contrast, only one chromosomal form was observed in individual karyotypes for the chromosomes I-V. These results could tally with the hypothesis of a haploid organisation for these chromosomes and strains, or, in the frame of a diploid organisation, with the hypothesis of a predominantly automictic sexuality giving rise to 2 identical forms of the homologues in the same strain.
Animals↗
Leishmania: sex, lies and karyotype.
The exploration of the genome of the tryponosomotid protozoan Leishmania has been difficult until recently owing to a number of obstacles, not least our ignorance of the ploidy and of the number of chromosomes (as in many other protozoa, the latter do not condense during mitosis), the uncertainty of the species concept in these allegedly asexual protozoa and the absence of classical genetic studies. Here, Patrick Bastien, Christine Bloineou and Michel Pages discuss the advances in this field brought about by the advent of molecular biology and its techniques, with on emphasis on ploidy and genetic exchange. In particular, they discuss the data from pulsed field gel electrophoresis (PFGE). When coupled with DNA restriction analysis, PFGE constitutes a powerful tool for the direct examination o f chromosomes of protozoa.
Journal Article↗