bluuebunny/crossref_metadata_2025_split huggingface dataset:
Targeted anthelminthic treatment of school children: effect of frequency of application on the intensity of Ascaris lumbricoides infection in children from rural Nigerian villages
Authors: Holland C. V. , Asaolu S. O. , Crompton D. W. T. , Whitehead R. R. , Coombs I. 
Published: June 2009

SUMMARYA study to compare the effects of different frequencies of targeted chemotherapy with levamisole (Ketrax: JAGAL Pharma, Lagos, Zeneca Pharmaceuticals UK) as an action for the control of Ascaris lumbricoides was carried out in 3 communities in rural Oyo State, Nigeria. The targeted group comprised children, aged 5 to 15 years, attending primary school within their village. Treatment was provided within the school with the assistance of the school teachers. Three frequencies of targeted treatment were offered. In one village targeted treatment was provided on 1 occasion in 1 year, in another village at two 6-monthly intervals and in the third village every 4 months. Prevalence and intensity (e.p.g.) of A. lumbricoides infection were determined immediately before and after the period of intervention using a modified Kato–Katz technique. In the villages which received treatment once and at 6-monthly intervals, a reduction in post-treatment intensity of A. lumbricoides was observed in the total population but this failed to attain statistical significance. In contrast, within the village which received 4-monthly targeted chemotherapy, a significant reduction in post-treatment intensity of A. lumbricoides was observed in the total population and in the targeted children. In general, reductions in the intensity of A. lumbricoides after intervention were not particularly pronounced in untreated children (aged 0–4 years) even in the 4-monthly targeted village, whereas in untreated adults, reductions approached statistical significance in villages which received targeted treatment once and at 4-monthly intervals.
Identification and sequence comparison of a cuticular collagen ofBrugia pahangi
Authors: Bisoffi M. , Betschart B. 
Published: June 2009

SUMMARYThe cuticle of filarial nematodes is a specialized extracellular matrix that covers the parasite and protects it from adverse conditions of the environment. As a surface structure it is in direct contact with the host defence mechanisms and therefore plays an important role in the molecular host-parasite relationship. Using polyclonal antisera raised against the insoluble components of the cuticle of the adult filarial parasiteBrugia pahangi, we have isolated cDNA clones encoding collagen molecules of the cuticle. The protein domain structure of cDNA clone Bpcol-1 was compared with the known structures of cuticular collagens of the nematodesBrugia malayi, Caenorhabditis elegans, Ascaris suumandHaemonchus contortus, confirming interspecies similarities. Using affinity-purified anti-Bpcol-1 antibodies we identified Bpcol-1 antigenic determinants in different nematode extracts, and determined the localization of such epitopes within the cuticle ofB. pahangi.
Effects of pH on a high conductance Ca-dependent chloride channel: a patch-clamp study inAscaris suum
Authors: Robertson A. P. , Martin R. J. 
Published: June 2009

SUMMARYPlasma membrane vesicles prepared from the bag region of the somatic muscle cells of the parasitic nematodeAscaris suumcontain high conductance, voltage sensitive, Ca-dependent chloride channels, suggested to be involved in the excretion of carboxylic acids produced by the anaerobic respiration of glucose (Valkanov, Martin & Dixon, 1994). The effect of altered pH on this channel was investigated using the patch-clamp technique and isolated inside-out membrane patches. Changes in pH had little effect on channel conductances and only a small effect on reversal potentials. Under control conditions (symmetrical pH 7·2) the channel had the highest probability of opening at ∼ — 35 mV (the resting membrane potential of the cell). At positive membrane potentials the probability of opening decreased. The Boltzmann equation was used to describe the relationship between membrane potential and probability of channel opening, and to calculate the effective gating charge. Reduction of external pH produced an increase in the probability of channel opening at hyper-polarized membrane potentials. An increase in internal pH caused a voltage-independent increase in the probability of channel opening and made the effective gating charge less negative. The effect of reducing internal pH was marked: the channel then opened most frequently at positive membrane potentials and the probability of opening at —35 mV was greatly reduced. The decrease in internal pH changed the polarity of the effective gating charge. A simple model was constructed to describe the effects of pH on channel gating.
Density-dependent processes in the transmission of human onchocerciasis: relationship between microfilarial intake and mortality of the simuliid vector
Authors: Basáñez M. G. , Townson H. , Williams J. R. , Frontado H. , Villamizar N. J. , Anderson R. M. 
Published: June 2009

SUMMARYIn order to construct an analytical model of onchocerciasis transmission, it is necessary to elucidate the functional relationships of the various population rate processes taking place within the human and vector hosts. Two previous papers have explored the evidence for density-dependent regulation in relation to microfilarial intake by, and larval development within, theSimulium host. This paper investigates the survivorship of wild-caught blackfly samples fed on subjects with different intensities ofOnchocerca volvulusmicrofilarial infection. Analyses were based on data for GuatemalanS. ochraceum s.l.(possessing a well-developed cibarial armature), West AfricanS. damnosum s.l.(forest species), and South VenezuelanS. guianense(the latter two lacking a toothed cibarium). The mean survival times of samples of the 3 species, kept under laboratory conditions, decreased as parasite intake increased, the rate of mortality being dependent on the fly’s age (measured as time post-feeding) and on the worm load acquired. An empirical, timedependent hazard function was fitted to observed death rates/fly/day which rose very shortly after engorgement, declined subsequently, and rose again throughout the extrinsic incubation period of the parasite. The parameters of this hazard model were all positively correlated with the density of microfilariae in the bloodmeal. Expressions of survivorship and life-expectancy as explicit functions of time post-feeding and mean parasite intake were derived. The average expectation of life at engorgement for uninfected flies in the laboratory was estimated to be around 1 week for both, armed and unarmed blackflies. Residual life-expectancy decreased with time post-feeding and microfilarial load in both categories of vectors. This decline (resulting from age- and parasite-dependent mortality rates) was much more pronounced in those species lacking a toothed fore-gut. Whilst a fraction of heavily infectedS. ochraceumwas able to survive the latent period of the parasite, being therefore potentially capable of transmitting the infection, equivalent worm loads inS. guianenseresulted in a drastic reduction of the expectation of infective life. These results provide additional evidence to support the hypothesis that, in the case of intrinsically susceptible vectors, unarmed simuliids are more efficient at low microfilarial loads, when the transmission rate from human to vector host is higher, and parasite-induced fly mortality is negligible. The opposite takes place in armed flies, which perform poorly at low parasite burdens and better at heavier loads, with little parasite-induced vector death.
Physiological effects of platyhelminth RFamide peptides on muscle-strip preparations ofFasciola hepatica(Trematoda: Digenea)
Authors: Marks N. J. , Johnson S. , Maule A. G. , Halton D. W. , Shaw C. , Geary T. G. , Moore S. , Thompson D. P. 
Published: June 2009

SUMMARYThe effects of each of the known platyhelminth neuropeptides were determined on muscle-strip preparations from the liver fluke,Fasciola hepatica. The activity of synthetic replicates of the C-terminal nonapeptide of neuropeptide F (NPF9,Moniezia expansa), and the FMRFamide-related peptides (FaRPs), GNFFRFamide, RYIRFamide, GYIRFamide and YIRFamide, were examined. Muscle-strip activity was recorded from 1 mm segments of muscle prepared from 28 to 32-day-old worms, using a photo-optic transducer system. None of the peptides (≤10 μM) altered baseline tension significantly; however, each of the peptides increased the amplitude and frequency of muscle contraction. The threshold for activity of each of the peptides examined was, respectively, 1 nM (RYIRFamide), 0·3 μM (GYIRFamide and YIRFamide), and 10 μM (GNFFRFamide and NPF9). All of the effects were reversible and repeatable, following wash-out. Muscle-strip integrity was tested following experimentation, using arecoline (10 μM) and high-K+bathing medium (90 mM K+).
Primary and secondary infections of the domestic chicken with Trichostrongylus tenuis (Nematoda), a parasite of red grouse, with observations on the effect on the caecal mucosa
Authors: Watson H. , Lee D. L. , Hudson P. J. 
Published: June 2009

SUMMARYThe course of primary and secondary infections with Trichostrongylus tenuis in the domestic chicken was investigated. Primary infections were established after the administration of single and trickle doses of infective-stage larvae. The worm burden in the caeca was highest after a single dose of 500 infective-stage larvae; this gave a mean of 87 nematodes per bird on days 8–9 of infection, 20 nematodes on day 14 and 0 on day 28 of infection. Following trickle doses of 60, 100, 200, 300, 400 or 500 infective-stage larvae, there was a rise and then a fall in nematode egg output in all groups. In chickens given a primary dose of 500 infective-stage larvae followed 30 days later by a single secondary dose of 500 infective-stage larvae, the mean worm burden during the secondary infection rose to 57 nematodes on day 9 of infection and then fell rapidly to 18 nematodes on day 15 and to 2 on day 30. Scanning electron microscopy showed changes in the caeca of infected birds, with the caecal surface being covered in a layer of mucus from 12 days after infection. Balls of blood-stained mucus containing nematodes were observed in the caecal droppings from day 9 of infection onwards. It is concluded that chickens rapidly expel an established infection of T. tenuis, unlike the normal host, the red grouse.
Speciation of cestoda. Evidence for two sibling species in the complex Bothrimonus nylandicus (Schneider 1902) (Cestoda: Cyathocephalidea)
Authors: Renaud F. , Gabrion C. 
Published: June 2009

SUMMARYUsing biochemical genetic methods, we have distinguished 2 sibling species in the complex Bothrimonus nylandicus (Schneider, 1902), which infest 2 congeneric species of sole (Solea lascaris and Solea impar) on European coasts (Atlantic and Mediterranean). Neither of the parasite species is specific for either of the sole species, but one of them is present all year round, whereas the other is absent in the autumn and winter and only appears in the spring, subsequently disappearing at the end of the summer. Only S. impar lives in the Mediterranean, and is equally infested by both cestodes, whereas both species occur in the Atlantic and each of them is preferentially infested by 1 species of cestode. The shortness of the adult stage of the parasite in the definitive host and the presence of 2 life-cycles associated with competition between the 2 hosts in the Atlantic could be responsible for the biological differences observed and for maintaining the sibling species in sympatry.
Cysteine metabolism in the cestodeHymenolepis diminuta
Authors: Gomez-Bautista M. , Barrett J. 
Published: June 2009

SUMMARYThe major pathways for cysteine catabolism inHymenolepis diminutahave been investigated. The parasite has an active cystathionine-β-synthase and, as in other tissues, this enzyme has a wide substrate specificity. However, the enzyme fromH. diminutadiffers significantly from the mammalian enzyme in showing a high serine sulphydrase activity and a high serine lyase activity. There was only low γ-cystathionase activity inH. diminutaand again the enzyme showed a range of substrate specificities. Cysteine aminotransferase activity was readily demonstrated in the tapeworm, but there was no evidence for 3-mercaptopyruvate sulphotransferase activity. An oxidative pathway for cysteine catabolism inH. diminutawas shown by the presence of cysteine dioxygenase and cysteine sulphinate transaminase. The properties of the helminth cysteine dioxygenase were very similar to those of rat liver.H. diminutawas able to reduce cystine to cysteine via a glutathione-cysteine transhydrogenase system.
A quick, simple method for purifying Leishmania mexicana amastigotes in large numbers
Authors: Hart D. T. , Vickerman K. , Coombs G. H. 
Published: June 2009

SUMMARYA rapid method for the bulk isolation of purified Leishmania mexicana mexicana amastigotes from parasite-induced lesions in experimentally infected mice is described. The procedure includes purification steps based on differences in net cell charge, lysis susceptibility and buoyant density between parasite and host cells. Yields of up to 2 × 1010 untransformed amastigotes with minimal contamination with host cells and cell debris can be obtained. At least 90 % of the purified amastigotes are viable as judged by light and electron microscopy, the staining of their lysosomes with acridine orange, their ability to transform to promastigotes and their infectivity to macrophages in vivo and in vitro.
Influence of variation in host strain and parasite isolate on inflammatory and antibody responses toTrichinella spiralisin mice
Authors: Goyal P. K. , Wakelin D. 
Published: June 2009

SUMMARYVariation in the immunogenicity of 3 isolates ofTrichinella spiraliswas assessed by the parameters of adult worm recovery, mast cell, eosinophil and antibody responses in mice of defined response phenotype. The levels of the protective, inflammatory and immune responses induced by infection differed between the isolates. Isolates showed considerable variation in the capacity to elicit mast cell and eosinophil responses. All induced increases in parasite-specific antibody, levels of total (IgGAM) antibody and of IgM and IgG isotypes rose steadily after infection, but there were significant differences in levels of response. The IgGAM response was correlated with the number of worms present, i.e. the greatest response was seen in low responder (C57BL/10) mice infected with the longest-surviving isolates. All isolates elicited specific IgG1 and IgG2a antibodies after infection, although, again, there were isolate-specific differences in the levels and kinetics of response. Levels of these isotypes were always higher, although not significantly so, in high-responder NIH mice. Low-responder mice showed higher IgE serum levels than high-responder mice after infection, one isolate giving much higher IgE values than the other two.
Rickettsia-like organisms and chitinase production in relation to transmission of trypanosomes by tsetse flies
Authors: Welburn S. C. , Arnold K. , Maudlin I. , Gooday G. W. 
Published: June 2009

SUMMARYRickettsia-like organisms (RLO) from tsetse midguts and mosquito cell cultures showed high levels of endochitinase activity. A line of Glossina morsitans morsitans highly susceptible to midgut trypanosome infection and with high incidence of RLO infection showed significantly greater chitinolytic activity than G. austeni which had low RLO incidence and were correspondingly refractory to midgut infection. Midgut infection rates of Trypanosoma brucei rhodesiense in G. m. morsitans showed a dose-related increase when flies were fed N-acetyl-D-glucosamine (GlcNAc) in the infective meal and for 4 subsequent days. A model is proposed for susceptibility to trypanosome infection based on the generation of GlcNAc by RLO endochitinase activity in tsetse pupae inhibiting midgut lectin in teneral flies.
Phylogenetic affinities of Acanthocephala: an assessment of ultrastructural evidence
Authors: Whitfield P. J. 
Published: June 2009

The phylogenetic relationships of the Acanthocephala are reviewed in the light of recent ultrastructural evidence. Comparisons of spermatozoan ultrastructure suggest that the Acanthocephala cannot be closely related to the Platyhelminthes and that the similarities which exist between cestodes and acanthocephalans are the result of convergence. Similarities in the spermatozoan ultrastructure of acanthocephalans, rotifers, nematomorphs and nematodes probably have a phylogenetic significance and suggest that the acanthocephalans have a close common ancestor with some at least of the Aschelminthes. The case for this affinity is strengthened by ultrastructural evidence concerning the body walls and muscles of acanthocephalans, nematodes and rotifers.I am indebted to Professor D. R. Arthur and Professor F. R. Whatley at King's College, London, for the provision of facilities. The work reported in this paper was undertaken during the tenure of a Research Fellowship from the Nuffield Foundation.
Distribution of schistosome genetic diversity within naturally infected Rattus rattus detected by RAPD markers
Authors: Barral V. , Morand S. , Pointier J. P. , Théron A. 
Published: June 2009

SUMMARYRandom amplified polymorphic DNA markers (RAPD) were used to visualize the genetic diversity within and between infrapopulations of Schistosoma mansoni recovered from the natural vertebrate host, Rattus rattus, trapped at an insular Guadeloupean focus. Phenotypes were characterized by the sex of the parasites and by 8 polymorphic markers generated by 3 primers. Among the 212 parasite individuals recovered from 10 infected rats, 78 genotypes were characterized. All the hosts naturally infected harboured multiple parasite genotypes with a maximum diversity of 28 genotypes/host. Phenotypic and genotypic diversity calculated by Shannon-Wiener's indices and Lynch and Milligan's estimators respectively is, on average, greater within than between hosts. Considering the very low snail infection rates observed in this focus and the rapid turnover of the vertebrate hosts, our results suggest that the high mobility of the vertebrate host and/or plurimiracidial snail infections could be factors responsible for parasite genetic diversity within hosts.
Adhesion of parasitized red blood cells to cultured endothelial cells: a flow-based study of isolates from Gambian children with falciparum malaria
Authors: Cooke B. M. , Morris-Jones S. , Greenwood B. M. , Nash G. B. 
Published: June 2009

SUMMARYAdhesion of parasitized red blood cells to vascular endothelium is thought to play an important role in the development of the ischaemic complications associated with severe falciparum malaria. Using a novel, flow-based assay, we have investigated the adhesion of parasitized red blood cells to formalin-fixed human umbilical vein endothelial cells (HUVEC), for isolates obtained from 32 Gambian subjects with mild or severe falciparum malaria. Red cells infected with wild strains ofPlasmodium falciparumwere able to adhere to HUVEC under physiologically relevant flow conditions, but the level of adhesion was highly variable, ranging from 1 to 688 adherent cells per mm2of HUVEC. Within isolates, some adherent parasitized cells remained stationary, whilst other formed less stable interactions and rolled slowly over the cell surface. There was no significant difference in adhesion of parasitized cells between isolates obtained from mild or severe cases of malaria, although a subset of isolates did show very high levels of adhesion. The results suggest that there is not a simple relationship between the adhesion of parasitized cells to cultured endothelial cells (presumably via the receptor ICAM-1) and the clinical severity of the disease, although variation in microvascular adhesionin vivomay still be a determinant of ischaemic complications.
Genetic structure of Trypanosoma cruzi populations from Argentina estimated from enzyme polymorphism
Authors: De Luca D'oro G. M. , Gardenal C. N. , Perret B. , Crisci J. V. , Montamat E. E. 
Published: June 2009

SUMMARYIsolates of Trypanosoma cruzi from human patients, domestic and sylvatic animals and vector insects were obtained in different areas of Argentina. Electrophoretic patterns of enzymes from extracts of 95 isolates were analysed. On the basis of zymograms providing information on 10 loci, 12 zymodemes are described according to their genotypes. Data presented show fixed heterozygosity, absence of segregation of genotypes, significant departures from Hardy–Weinberg equilibrium, and over-represented genotypes. This evidence supports the hypothesis that sexual reproduction is very restricted or absent in this parasite. The proportion of polymorphic loci is 80%. The expected mean heterozygosity per locus (He) is 0·43, while the observed value (Ho) is 0·24. Differences between these values may be explained by accepting a basically clonal structure for T. cruzi. The data matrix of 12 zymodemes using 28 characters was analysed using a Wagner parsimony algorithm. Two equally most parsimonious unrooted trees were generated; both have 39 steps. The results show clusters clearly separated according to the geographical origin of the stocks. There are some indications of some correlations between genetic composition of the parasite and the clinical picture of the infection in human patients.
Localization, turnover and conservation of gp15/400 in different stages ofBrugia malayi
Authors: Selkirk M. E. , Gregory W. F. , Jenkins R. E. , Maizels R. M. 
Published: June 2009

SUMMARYThe expression of a protein complex designated gp15/400, previously identified via extrinsic iodination of adultBrugia malayi, was examined by labelling all stages found in the mammalian host and immunoprecipitation with a specific antibody raised to a recombinant protein. In this way, gp15/400 could be detected in L3, L4, adult worms and microfilariae recovered from jirds and labelled with Bolton–Hunter reagent. Metabolic labelling indicated that gp15/400 was released into culture medium when adult worms were maintainedin vitro, but at a rate slower than that of gp29, the major soluble cuticular glycoprotein. Immuno-electron microscopy showed that the protein complex was broadly distributed in different tissues, although it was not detectable in the cuticle of adult worms. Dense labelling was observed in the matrix of the basal laminae bordering the hypodermis, somatic musculature and oesophagus, and lower but significant labelling was seen in the cells overlying these extracellular matrices. Hybridization of genomic DNA with a cDNA probe encoding gp15/400 indicated that homologous genes were present inDirofilaria immitisandAcanthocheilonema viteae. The failure to detect related genes in non-filarial nematodes was presumed to be due to divergence beyond the practical limits of detection by nucleic acid probes, as antibody reagents showed that the protein cross-reacted immunologically with ABA-1, a major protein allergen from the body fluid ofAscaris.