bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antigen localization and the induction of resistance in mice vaccinated with irradiated cercariae ofSchistosoma mansoni
Authors: Mountford A. P. , Coulson P. S. , Wilson R. A. 
Published: June 2009

SUMMARYThe fate of75Se-labelled parasites and their released pre-synthesized macromolecules has been followed in three murine infection models. Parasite numbers in specific tissues were determined by autoradiography, and released material was estimated by gamma-counting of tissues, with adjustment for the presence of parasite-associated radiolabel. Marked differences were found between the three models. The pattern of migration of normal schistosomula was similar to that previously reported. In addition we have described the transit of parasites through the lymph nodes draining the infection site. Significant quantities of released material were detected in the skin, draining lymph nodes, bloodstream and liver. The circulating material was of parasite origin, macromolecular, and hence potentially antigenic. In comparison to the normal infection, radiation-attenuated parasites (inducing a high level of resistance to challenge) persisted in the skin, draining lymph nodes and lungs, releasing a proportionally greater amount of material in the nodes. In mice exposed to attenuated parasites and treated with the compound ROl1–3128 at 24 h (inducing a low level of resistance) there was an early death and rapid clearance of the parasites whilst still in the skin. This situation resulted in the highest levels of released material in the skin, bloodstream and liver, but negligible levels in the draining lymph nodes. We suggest that the persistence of radiation-attenuated parasites in the skin and draining lymph nodes, together with the prolonged release of antigen in the latter site, compared to the normal situation, are major factors in the induction of resistance.
Molecular cloning of Taenia solium genomic DNA and characterization of taeniid cestodes by DNA analysis
Authors: Rishi A. K. , McManus D. P. 
Published: June 2009

SUMMARYTotal DNAs, isolated from a range of taeniid cestodes (Taenia solium, T. saginata, T. pisiformis, T. crassiceps, T. hydatigena, T. ovis, T. multiceps and T. taeniaeformis), have been subjected to restriction enzyme digestion, Southern transfer and hybridization analysis using cloned fragments of the ribosomal RNA gene of Schistosoma mansoni. Substantial inter-specific genetic differences have been revealed on the basis of characteristic hybridization patterns for each of the taeniid cestode species. Furthermore, a random genomic DNA library has been constructed in the vector plasmid pAT153 using DNA extracted from a pig isolate (Indian origin) of T. solium. A panel of taeniid cestode DNAs including DNA from Echinococcus granulosus, has been used in conjunction with hybridization and restriction enzyme analysis to identify in the library a single recombinant plasmid with a T. solium-specific insert (coded pTS10) and two recombinant plasmids with T. solium inserts having selective specificities for T. solium and T. ovis (coded pTS17) and T. solium, T. saginata, T. ovis and T. multiceps (coded pTS28). These recombinant plasmids and the cloned fragments of the ribosomal RNA gene of S. mansoni have been used in restriction endonuclease, Southern transfer and hybridization analysis to detect intra-specific genetic variation in cysticerci of T. solium from India, Mexico and Zimbabwe. In addition, pTS10 and pTS17 have been used in a simple dot-blot assay to distinguish T. solium from T. saginata.
Population dynamics in echinococcosis and cysticercosis: economic assessment of control strategies for Echinococcus granulosus, Taenia ovis and T. hydatigena
Authors: Lawson J. R. , Roberts M. G. , Gemmell M. A. , Best S. J. 
Published: June 2009

SUMMARYAn official control programme against Echinococcus granulosus and Taenia hydatigena has been in operation in New Zealand for more than 28 years and against Taenia ovis for more than 18 years. This unique effort to control three metazoan parasites at the same time has led to a change from endemic to extinction status for E. granulosus but only a change from hyperendemic to endemic status for T. hydatigena and T. ovis. This has presented problems in determining the most cost-effective future control strategies. To facilitate this, a benefit/cost analysis of 20 options for the combined control of E. granulosus, T. hydatigena and T. ovis in New Zealand was undertaken. This showed that for E. granulosus a future change from the current non-targeted to a targeted approach is strongly indicated. For T. ovis 6 options were cost-effective using a discount rate of 10%. These were (1) a targeted control package using a vaccine in the non-targeted attack phase; (2) a targeted control package using a larvicide in the attack phase; (3) the transfer of all losses due to and responsibility for the control of T. ovis to the producer who administers a larvicide to sheep to be killed for dog food; (4) the transfer of all losses due to and responsibility for the control of T. ovis to the producer who administers praziquantel every 6 weeks to dogs; (5) and (6) two options involving the discontinuation of control. Control of T. hydatigena was assumed to be an incidental outcome of the policies for the other two parasites.
A general model for the African trypanosomiases
Authors: Rogers D. J. 
Published: June 2009

SUMMARYA general mathematical model of a vector-borne disease involving two vertebrate host species and one insect vector species is described. The model is easily extended to other situations involving more than two hosts and one vector species. The model, which was developed from the single-host model for malaria described by Aron & May (1982), is applied to the African trypanosomiases and allows for incubation and immune periods in the two host species and for variable efficiency of transmission of different trypanosome species from the vertebrates to the vectors and vice versa. Equations are derived for equilibrium disease prevalence in each of the species involved. Model predictions are examined by 3-dimensional phase-plane analysis, which is presented as a simple extension of the 2-dimensional phase-plane analysis of the malaria model. Parameter values appropriate for the African trypanosomiases are derived from the literature, and a typical West African village situation is considered, with 300 humans, 50 domestic animals and an average population of 5000 tsetse flies. The model predicts equilibrium prevalences of Trypanosoma vivax, T. congolense and T. brucei of 47·0, 45·8 and 28·7% respectively in the animal hosts, 24·2, 3·4 and 0·15% in the tsetse vectors, and a 7·0% infection of humans with human-infective T. brucei. The contribution to the basic rate of reproduction of the human-infective T. brucei is only 0·11 from the human hosts and 2·54 from the animal hosts, indicating that in the situation modelled human sleeping sickness cannot be maintained in the human hosts alone. The animal reservoir is therefore crucial in determining not only the continued occurrence of the disease in humans, but its prevalence in these hosts as well. The effect of changing average fly density on equilibrium disease prevalences is examined, together with the effect of seasonal changes in fly numbers on disease incidence. In a seasonal situation changes in fly mortality rates affect both future population size and infection rate. Peak disease incidence lags behind peak fly numbers, and that in the less favoured host lags behind that in the more favoured host. Near the threshold fly density for disease transmission disease incidence is more changeable than at higher fly densities and may even exceed equilibrium prevalence at the same average fly density (because most hosts are susceptible at the time that fly numbers begin their annual increase). The implications of the model for disease control are discussed. Identifying the precise role of the animal reservoir may suggest that treating such animals will achieve a greater reduction of human sleeping sickness than direct treatment of the humans alone. Statistically significant results of control campaigns may also be more easily shown by monitoring the non-human reservoirs. The model provides a means by which a correct perspective view can be obtained of the complex epidemiology and epizootiology of the African trypanosomiases.
Effects on inhibition of development of the transfer of Ostertagia ostertagi between geographical regions of Australia
Authors: Smeal M. G. , Donald A. B. 
Published: June 2009

SUMMARYPasture plots in a warm coastal region were separately contaminated in the autumn, winter and spring with eggs of a coastal strain of Ostertagia ostertagi derived from dairy calves. At the same times, a parallel set of plots was contaminated by a strain transferred from within a beef cattle management system in a cooler tablelands region. A reciprocal transfer of the coastal strain was also made to the tablelands, where pasture plots were contaminated with eggs of both strains of O. ostertagi in winter. Successive groups of parasite-free calves were grazed on the plots for 10–14 days at 4-week intervals and then killed for worm counts 14 days after their removal from pasture. In both environments, irrespective of the season of pasture contamination, inhibition of development reached a maximum in spring and the two strains differed only in the proportion of the population inhibited, which was significantly greater for the table- lands strain. There was no strain difference for either numbers of infective larvae on pasture or total O. ostertagi numbers. This suggested that the difference between coastal and tablelands populations in the extent of inhibition is genetically determined. If an environmental stimulus was implicated in the spring occurrence of inhibition, the stimulus was provided equally in coastal and tablelands environments and it cannot be exposure to low temperatures.
The effect of dehydration and rehydration on salt loss in the second-stage larvae of Anguina tritici
Authors: Womersley C. 
Published: June 2009

SUMMARYThe effect of repeated dehydration and hydration on the salt content of 2nd-stage larvae of Anguina tritici was studied. The sodium, potassium, magnesium and calcium contents of the larvae after subjection to varying periods of desiccation and rehydration were determined with atomic absorption spectrophotometry and flame photometry. External cation concentrations on the cuticle of the head, middle body and tail regions were determined semi-quantitatively with scanning electron microscopy in conjunction with X-ray analysis (EDAX). Salt concentrations decreased with each dehydration/rehydration cycle. The greatest loss occurred on revival from the first desiccation period. The results indicated that A. tritici was incapable of regulating it's internal sodium content during revival, but suggested a limited ability to control potassium, magnesium and calcium loss. Salt loss through the nematode cuticle was restricted to potassium and calcium during desiccation. The salt losses encountered are discussed in relation to nematode osmoregulation and to the survival of the nematode in the anhydrobiotic state.
Observations on relationships between infective juveniles of bovine lungworm, Dictyocaulus viviparus (Nematoda: Strongylida) and the fungi, Pilobolus kleinii and P. crystallinus (Zygomycotina: Zygomycetes)
Authors: Doncaster C. C. 
Published: June 2009

SUMMARYInfective 3rd-stage larvae of Dictyocaulus viviparus were filmed whilst climbing sporangiophores of the coprophilous fungus, Pilobolus and invading sporangia in numbers up to about 50, shortly before the sporangia were explosively discharged. Like the sporangiophores of Pilobolus the nematodes reacted positively towards light. Robinson (1962) demonstrated the spectacular way in which D. viviparus can be dispersed by Pilobolus, although he saw the nematodes accumulating only on top of the sporangia. Hazards including desiccation would offset the advantage of dispersal unless protection is somehow provided. Free D. viviparus larvae are susceptible to desiccation and discharged sporangia appear to dry quickly, so what protection, if any, operates? Several other nematodes that are susceptible to desiccation survive because structures surrounding them dry quickly (for example, an ensheathing cuticle, egg-shell, gelatinous ‘egg-sac’ matrix) and in doing so form barriers which limit the rate of water loss from the nematode within. Such dried sporangia of Pilobolus could aid survival of the ensheathed D. viviparus larvae inside them by retarding desiccation of the nematodes, in much the same way that within cysts of Globodera and Heterodera spp. the cyst wall, egg matrix and outer eggs protect the inner eggs by reducing the rate, if not the extent, of water loss. The sporangium wall may also protect the nematodes from harmful ultraviolet irradiation and from being washed by rain into less advantageous situations.
Characterization of proteinases in extracts of adultHaemonchus contortus, the ovine abomasal nematode
Authors: Knox D. P. , Redmond D. L. , Jones D. G. 
Published: June 2009

SUMMARYThe degradation of several protein substrates, including the blood proteins haemoglobin, albumin and fibrinogen, by proteinases present in extracts of adultHaemonchus contortuswas examined over a broad pH range. These proteinases were further characterized on the basis of substrate specificity, inhibitor sensitivity and molecular size by spectrophotometric and substrate gel analysis. The majority of the proteinases capable of degrading the blood proteins tested were active at acidic pH and could be ascribed to the cysteine proteinase class. In addition, evidence is presented that these proteinases are differentially recognized and inhibited by immune sera and that parasites capable of withstanding protective host immune responses exhibit modified expression of proteinases.
The attachment of the ancyrocephalid monogenean Haliotrema balisticus to the gills of the trigger fish, Balistes capriscus (= carolinensis)
Authors: Kearn G. C. 
Published: June 2009

Haliotrema balisticus attaches itself between the secondary gill lamellae of its host, Balistes caprisctis (= carolinensis), by means of a pair of ventral hamuli, which point ventrolaterally, and a pair of dorsal hamuli which point in a dorsal direction. The ventral hamuli, each of which pivots at the end of a ventral connecting bar, are operated by a pair of extrinsic muscles. The tendinous regions of these muscles pass through fibrous loops attached to the ventral hamuli and then join each other in the mid-line. Such an arrangement has a high mechanical advantage which may reduce the expenditure of energy required to maintain the hamuli in position in the gill tissue in the face of a strong gillventilating current and may also preserve the mobility of the free region of the body.The dorsal hamuli are not operated by the muscles and tendons associated with the ventral hamuli.Marginal hooklets and glands play subsidiary roles in attachment.I wish to express my thanks to Commander J. Parreira, Director of the Aquario Vasco da Gama in Lisbon, and to the Staff of the Aquario, in particular to Mr A. Ferreira, for their kind assistance and hospitality. I am also grateful to Dr Maria Monteiro and to Dr Maria Baptista. I am indebted to the Calouste Gulbenkian Foundation for a grant which made my visit to Portugal possible.
Schistosoma mansonielastase: an immune target regulated during the parasite life-cycle
Authors: Pierrot C. , Godin C. , Liu J. L. , Capron A. , Khalife J. 
Published: June 2009

SUMMARYRecombinantSchistosoma mansonielastase was expressed inEscherichia coliand an antiserum raised against the re-combinant protein was used to investigate stage-specific control of elastase in the parasite, and to determine whether the enzyme could form the basis of a strategy to prevent larval invasion of the host. Results showed that the expression of elastase is developmentally regulated, even if the basal promoter activity does not seem to be stage specific. The analysis of mRNA expression showed the presence of elastase transcript in adult worms although we could not detect the protein at this stage, suggesting thatS. mansoniemploys a form of translational control. The measurement of elastase levels in supernatants of culture schistosomula combined with the localization of elastase in cercariae invading mouse skin showed that the enzyme is heavily released during penetration. Finally, we studied the cytotoxic activity of rat anti-elastase sera, and the analysis of the isotypic profile suggested that IgG2a anti-elastase may be responsible for the cytotoxic effect.
The monoxenic culture of beet eelworm (Heterodera schachtii Schm.) on excised roots of sugar beet (Beta vulgaris L.)
Authors: Moriarty F. 
Published: June 2009

A method is described for obtaining sterile second-instar larvae of beet eelworm, Heterodera schachtii Schm., and culturing them to the adult stage on sterile excised roots of sugar beet, Beta vulgaris L. It was shown that beet eelworm is a primary pathogen, for sound uninjured radicles were invaded by larvae, and normal development of adult males and females followed. No females were fertilized, and no eggs were produced, which suggested that parthenogenesis cannot occur. Eelworm development stimulated the production of lateral roots. More adult females developed on radicles inoculated 24 hr. after excision than on radicles inoculated 72 hr. after excision, which may be related to the occurrence of maximum root extension during the first few days after excision. It is suggested that there are two parts in root tissue reactions: a thickening of cell walls as a wound reaction to mechanical injury, and formation of a syncytium in response to a chemical stimulus from the eelworm.I thank my wife for assistance with this work, which was financed by the Sugar Beet Research and Education Committee.
Comparisons between microvascular changes in cerebral and non-cerebral malaria in mice, using the retinal whole-mount technique
Authors: Neill A. L. , Chan-Ling T. , Hunt N. H. 
Published: June 2009

SUMMARYCBA/T6 mice inoculated withPlasmodium bergheiANKA strain (PbA) exhibited cerebral symptoms and died from cerebral malaria 6–8 days p.i. whereas DBA/2J mice developed (around days 6–9) a non-fatal cerebral malaria, with milder cerebral symptoms, and died between days 15 and 22 from other malaria-related complications. When inoculated withP. bergheiK173 (Pb) these mouse strains did not develop cerebral malaria. These mouse/parasite strain combinations were used, in conjunction with the retinal whole-mount technique, to elucidate factors critical in the pathology of murine cerebral malaria. CBA/T6 mice infected with PbA (PbA-CBA mice) demonstrated mild changes in vascular permeability as early as days 2–3, prior to the appearance on day 5 of cerebral symptoms, whereas mice with non-cerebral malaria did not show any vascular permeability changes until the very late stage of the disease (days 14–22). In the PbA infections, progressive deterioration of endothelial barrier properties, demonstrated by Evans' Blue leakage both generally and from specific focal areas, as well as a developing monocytosis and adherence of mononuclear cells to the endothelium of the retinal vessels continued until death (in CBA/T6 mice) or resolution (in DBA/2J mice). Adherent monocytes, particularly in PbA-CBA mice, were associated with reduced Hoechst staining of individual endothelial cells and a banking up proximally of both parasitized and non-parasitized blood cells in the small blood vessels, often with accompanying focal leakage of Evans' Blue from the retinal vessels. The occurrence and severity of these early changes in the microcirculation correlated with the subsequent development of cerebral symptoms. Monocyte margination appeared to be the most significant factor associated with the development of cerebral symptoms.
Dynamics of gastropod infection by first-stage larvae of protostrongylid nematodes — a model
Authors: Řezáč P. , Kindlmann P. , Dostálková I. , Holasová E. 
Published: June 2009

SUMMARYFor the description of the dynamics of snail infection by the 1st-stage larvae of protostrongylid nematodes, Skorping (1988) used the miracidia-snail model (Anderson, 1978). Here it is shown that, in contrast to miracidia, in protostrongylids the instantaneous rate of infection, α, is strongly dependent on the experimental design (factors like host size and size of the experimental arena). With respect to this, Anderson's model is modified by incorporation of the experimental design. The parameter α in its new sense as the rate of penetration (probability that the infective larva will penetrate into the host during a time unit) is shown to remain dependent, although much less so, on the experimental design. Only the inclusion of the assumed effect of mucus, which decreases the rate of penetration, yields a parameter α0 (the initial rate of penetration), which is completely independent of the design of the experiment, is species-specific, and also gives the best fit to the empirical data. As the above-mentioned factors can strongly influence the value of the instantaneous rate of infection in the laboratory experiments, α0 is more suitable as a measure of either the larval infectivity for the snail or snail susceptibility to infection by the protostrongylid larvae.
Phylogeny and evolution of the piroplasms
Authors: Allsopp M. T. E. P. , Cavalier-Smith T. , Waal D. T. De , Allsopp B. A. 
Published: June 2009

SUMMARYSmall subunit ribosomal RNA (srRNA) genes of three Theileria species, one Cytauxzoon and four Babesia species were amplified using the polymerase chain reaction (PCR), cloned and sequenced. Our sequences were aligned with srRNA sequences previously published for eight species of Apicomplexa, one ciliate and one dinoflagellate, the last two being included as free-living outgroup species. Phylogenetic relationships between the organisms were inferred by four in-dependent methods of phylogenetic tree construction using the ciliate Oxytricha nova to root the trees. Our trees fail to show a consensus branching order. They do, however, clearly indicate that the theilerias form a monophyletic taxon derived from a paraphyletic group which includes the species B. equi, C. felis and B. rodhaini. The distance trees indicate that the babesias sensu stricto (B. canis, B. caballi, B. bigemina and B. bovis) form another monophyletic taxon which diverged before the theilerias separated from the above-mentioned paraphyletic group. The parsimony and maximum likelihood trees suggest that the babesias and theilerias are sister taxa, both of which were derived from the paraphyletic group.