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Betschart, Bruno

Nom
Betschart, Bruno
Affiliation principale
Fonction
Professeur.e émérite
Email
bruno.betschart@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/302

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  • Publication
    Accès libre
    Light and electron microscopy studies of the midgut and salivary glands of second and third instars of the horse stomach bot, Gasterophilus intestinalis
    (2010)
    Roelfstra, Lise-Lore
    ;
    Vlimant, Michèle 
    ;
    Betschart, Bruno 
    ;
    Pfister, Kurt 
    ;
    Diehl, Peter-Allan 
    A morphological study of the midgut and salivary glands of second and third instars of Gasterophilus intestinalis (De Geer) (Diptera: Oestridae) was conducted by light, scanning and transmission electron microscopy. The midgut is anteriorly delimited by a proventriculus, without caeca, and is composed of posterior foregut and anterior midgut tissue from which a double-layered peritrophic matrix is produced. The midgut can be divided into anterior, median and posterior regions on the basis of the structural and physiological variations of the columnar cells which occur along its length. Two other types of cell were identified: regenerative cells scattered throughout the columnar cells, and, more rarely, endocrine cells of two structural types (closed and open). Different secretion mechanisms (merocrine, apocrine and microapocrine) occur along the midgut epithelium. Abundant microorganisms are observed in the endoperitrophic space of the anterior midgut. The origin and nature of these microorganisms remain unknown. No structural differences are observed between the second and third instar midguts. The salivary glands of G. intestinalis second and third instars consist of a pair of elongated tubular structures connected to efferent ducts which unite to form a single deferent duct linked dorsally to the pharynx. Several intermediate cells, without cuticle, make the junction with the salivary gland epithelium layer. Cytological characteristics of the gland epithelial cells demonstrate high cellular activity and some structural variations are noticed between the two larval stages.
  • Publication
    Accès libre
    Quantifying the Evolution and Impact of Antimalarial Drug Resistance: Drug Use, Spread of Resistance, and Drug Failure over a 12-Year Period in Papua New Guinea
    (2010)
    Nsanzabana, Christian
    ;
    Hastings, Ian M.
    ;
    Marfurt, Jutta
    ;
    Müller, Ivo
    ;
    Baea, Kay
    ;
    Rare, Lawrence
    ;
    Schapira, Allan
    ;
    Felger, Ingrid
    ;
    Betschart, Bruno 
    ;
    Smith, Thomas A.
    ;
    Beck, Hans-Peter
    ;
    Genton, Blaise
    Background. Antimalarial use is a key factor driving drug resistance and reduced treatment effectiveness in Plasmodium falciparum malaria, but there are few formal, quantitative analyses of this process.
    Methods. We analyzed drug usage, drug failure rates, and the frequencies of mutations and haplotypes known to be associated with drug resistance over a 12-year period (1991–2002) in a site in Papua New Guinea. This period included 2 successive treatment policies: amodiaquine (AQ) or chloroquine (CQ) from 1991 through 2000 and their subsequent replacement by sulfadoxine-pyrimethamine (SP) plus AQ or SP plus CQ.
    Results. Drug use approximated 1 treatment per person-year and was associated with increasing frequencies of pfcrt and pfmdr1 mutations and of treatment failure. The frequency of pfdhfr mutations also increased, especially after the change in treatment policy. Treatment failure rates multiplied by 3.5 between 1996 and 2000 but then decreased dramatically after treatment policy change.
    Conclusions. With high levels of resistance to CQ, AQ, and SP, the deployment of the combination of both drugs appears to increase clinical effectiveness but does not decelerate growth of resistance. Our estimates of mutation and haplotype frequencies provide estimates of selection coefficients acting in this environment, which are key parameters for understanding the dynamics of resistance.
  • Publication
    Accès libre
    Protein expression profile of Gasterophilus intestinalis larvae causing horse gastric myiasis and characterization of horse immune reaction
    (2009)
    Roelfstra, Liselore
    ;
    Deeg, Cornelia A.
    ;
    Hauck, Stefanie M.
    ;
    Buse, Christina
    ;
    Membrez, Mathieu
    ;
    Betschart, Bruno 
    ;
    Pfister, Kurt 
    Background Little information is available on the immunological aspect of parasitic Gasterophilus intestinalis (Diptera, Oestridae) larvae causing horse gastric myiasis. The objectives of this research were to analyze the protein content of larval crude extracts of the migrating second and third larvae (L2 and L3) of G. intestinalis in order to characterize the immune response of horses.
    Results The proteomic profile of L2 and L3, investigated by using one and two dimensional approaches, revealed a migration pattern specific to each larval stage. Furthermore, Western blots were performed with horse sera and with sera of Balb/c mice immunised with the larval crude extracts of L2 or L3, revealing a different immune reaction in naturally infected horses vs. artificially induced immune reaction in mice. The comparisons of the immunoblot profiles demonstrate that the stage L2 is more immunogenic than the stage L3 most likely as an effect of the highest enzymatic production of L2 while migrating through the host tissues. Fifteen proteins were identified by mass spectrometry.
    Conclusion This work provides further information into the understanding of the interaction between G. intestinalis and their host and by contributing a novel scheme of the proteomic profile of the main larval stages.
  • Publication
    Métadonnées seulement
    A study on the seasonal epidemiology of Anoplocephala spp.-infection in horses and the appropriate treatment using a praziquantel gel (Droncit (R) 9% oral gel)
    (2006)
    Roelfstra, Lise-Lore
    ;
    Betschart, Bruno 
    ;
    Pfister, Kurt 
    In a study on the seasonal dynamics of the gastro-intestinal nematode egg production in horses, one breeding farm also revealed a particularly high prevalence of Anoplocephola spp. infection. Consequently, this farm was chosen for analysing the seasonal pattern of the tapeworm egg excretion over a one year period in order to establish the most favourable periods for an appropriate and successful cestocidal treatment. The seasonal analysis showed a significantly higher (p < 0,05) Anoplocephala spp. egg excretion between July and October, i.e. during the second part of the grazing period. This result clearly underlines the importance of a cestocidal treatment during that period of the year Subsequently, horses of this farm and of a second farm with a high prevalence of Anoplocephola spp. were used to evaluate the efficacy of praziquantel in a specific oral gel formulation for horses under field conditions. The efficacy of praziquantel was tested in a total of 33 horses from the two farms harbouring a coproscopically detected Anoplocephala spp. infection prior to treatment. Praziquantel (Droncit (R) 9%, oral gel, 1mg/kg bodyweight) was administered to the horses according to their body weight. The efficacy of the drug was evaluated ten days after treatment by a double faecal ana lysis. Thereby, no Anoplocepholo spp. eggs were found. in the faeces of 32 horses (97%). The single horse remaining positive for Anoplocephola spp. eggs did not completely swallow the anthelmintic gel and consequently, did not receive the appropriate dose of the drug.
  • Publication
    Métadonnées seulement
  • Publication
    Accès libre
    Prospect for anthelminthic plants in the Ivory Coast using ethnobotanical criteria
    (2004)
    Diehl, M. S.
    ;
    Kamanzi Atindehou, K.
    ;
    Téré, H.
    ;
    Betschart, Bruno 
    Sixty plant species were collected in the Ivory Coast on the basis of an ethnobotanical literature using the following three criteria: activity against worms, diarrhoea and/or abdominal pain. Eighty six plant extracts were prepared using 90% ethanol and tested for potential anthelminthic activities with a larvicidal test of Haemonchus contortus. 25.6% of the extracts showed a high activity, 12.8% were active or marginally active and the remaining 61.6% were inactive. The fact that a relatively high percentage of the plants species (50%) had an activity can be explained by the initial preselection of the plants on the basis of ethnobotanical indications.
  • Publication
    Métadonnées seulement
    Prophylaxis failure due to probable mefloquine resistant P-falciparum from Tanzania
    (2003)
    Wichmann, O
    ;
    Betschart, Bruno 
    ;
    Loscher, T
    ;
    Nothdurft, H D
    ;
    Sonnenburg, F V
    ;
    Jelinek, T
    Failures of mefloquine prophylaxis in travellers returning from Africa have been reported repeatedly. Noncompliance to chemoprophylaxis is considered to be a major factor for failure. Only few reports on mefloquine prophylaxis failure in sub-Saharan Africa were able to report blood levels of the drug that were sufficient for prophylactic effectiveness. We report the case of a 44-year-old German female who travelled to Tanzania for 3 weeks. The patient reported that she never missed a dose of mefloquine during her weekly prophylaxis schedule. Four weeks after returning from Tanzania, the patient presented with fever, headache and myalgia. Only a few trophozoites of Plasmodium falciparum were found in a thick film. Blood levels of mefloquine at that stage were at 1400 ng/ml, thus largely excluding non-compliance and malabsorption. To our knowledge, this is the first case of confirmed prophylaxis failure due to mefloquine resistance in East Africa. (C) 2003 Elsevier Science B.V. All rights reserved.
  • Publication
    Métadonnées seulement
    Seasonal epidemiology of ticks and aspects of cowdriosis in N'Dama village cattle in the Central Guinea savannah of Cote d'Ivoire
    (2002)
    Knopf, L
    ;
    Komoin-Oka, C
    ;
    Betschart, Bruno 
    ;
    Jongejan, Frans
    ;
    Gottstein, Bruno
    ;
    Zinsstag, Jacob
    In the Central Guinea savannah of Cote d'Ivoire, cattle breeding started only similar to30 years ago. The impact of parasitism on the overall health status and productivity of the trypanotolerant N'Dama cattle in this area is unknown. In close collaboration with national veterinary institutions and local farmers, we studied spectrum, burden and seasonal dynamics of ticks (including aspects of cow-driosis) on N'Dama village cattle. In a longitudinal study, three randomly selected cattle herds (traditional farming type) of one village were examined repeatedly for ticks. Spectrum, burden, seasonal epidemiology of ticks were assessed. In these traditional herds (which lack (ecto)parasite management), all animals were infested by ticks at monthly counts. Five different tick species were identified; the four genera in order of frequency were: Amblyomma (overall prevalence 96%), Boophilus (47%), Hyalomina (
  • Publication
    Accès libre
    Isolation, characterisation and organisation of histone H1 genes in African trypanosomes
    (2001)
    Grüter, Eric
    ;
    Betschart, Bruno 
    A tandemly arranged gene family coding for histone H1 in African trypanosomes is described. Many variants, differing by some substitutions and/or deletions in their monotone and repetitive amino acid sequences, are found. The different variants can be sorted into three subtypes using their N-terminal region. PCR amplification experiments with primers specific to these three H1 subtypes suggest that the genes may be separated into two transcriptional units. Heterogeneity among species, subspecies and even strains was found. The transcripts are polyadenylated and the trans-splicing site is located very closely to the start codon. The intergenic regions are typical when compared to other polycistronic clusters described in trypanosomes. Amino acid sequence motifs may explain differences seen in chromatin compaction patterns between African and American trypanosomes.