bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hymenolepis diminutaandH. microstoma: uptake of cyclosporin A and drug binding to parasite cyclophilins
Authors: Roberts H. C. , Sternberg J. M. , Chappell L. H. 
Published: June 2009

SUMMARYCyclosporin A (CsA) acts as a powerful immunosuppressant through its binding to the cytosolic isomerase, cyclophilin (CyP), forming a complex which inhibits the phosphatase activity of calcineurin. The drug is also selectively anti-parasitic but its mode of action remains unknown. The mouse tapeworm,Hymenolepis microstomais sensitive to CsA, but the rat tapeworm,H. diminutais not susceptible either in rats, mice orin vitro. Using these two tapeworm models, the uptake and binding of CsA were examined in relation to parasite cyclophilins. Uptake and compartmentalization of the drug were markedly different in the two species:H. microstomatakes up more drug than doesH. diminutaand sequesters more drug into intracellular compartments. Characterization of cyclophilins using both CsA binding and isomerase activity assays reveals thatH. microstomapossesses two cyclophilin isoforms (Mr17700 and 21400) with isomerase activity that is inhibited by CsA. Using identical assays, we have been unable to demonstrate CsA-binding proteins or CsA-sensitive isomerase activity inH. diminuta. These data suggest that the anthelmintic action of CsA relates in some way to the presence and function of parasite cyclophilins.
Effects of larval Digenea on the free amino acid pool of Littorina littorea (L.)
Authors: Watts Stuart D. M. 
Published: June 2009

Quantitative chromatographic analysis of the free amino acids of the head–foot muscle of uninfected and infected Littorina littorea indicates that there is specific variation in the physiological effects of parasitism. The total concentration of free amino acids in the host head–foot muscle showed an increase of 10·9% with infections of Cryptocotyle lingua rediae, a decrease of 12·7% with infections of Himasthla leptosoma rediae and a decrease of 57·5% with infections of Cercaria emasculans sporocysts. These effects probably depend on three main factors namely, the nature, size and mobility of the larvae of the three species concerned and the influence of these factors in determining the extent of any damage to the hepatopancreas of the host.The larvae of C. lingua are probably less affected by the changes they induce in the free amino acid pool of the host than the larvae of H. leptosoma and Cercaria emasculans which induce changes equivalent to starvation.This work was conducted during the tenure of a Science Research Council Studentship. I would like to thank Professor B. John and Mr A. R. Hockley for their helpful advice and criticism.
The ultrastructure of the epidermis of the redia and cercaria ofParorchis acanthus,Nicoll. A study by scanning and transmission electron-microscopy
Authors: Rees Gwendolen 
Published: June 2009

Scanning electron-micrographs have shown the covering of microvilli on the surface of the redia ofParorchis acanthus.In the contracted state the elongated microvilli with bulbous extremities seen in the surface grooves may be the result of compression. The surface of the epidermis of the cercaria is smooth on a large area of the ventral surface and lattice-like with microvilli, laterally, anteriorly, dorsally and on the tail. The spines on the body can be withdrawn into sheaths by the contraction of muscle fibres inserted into the basement lamina below each spine.I would like to express my sincere gratitude to Dr I. ap Gwynn of this department for preparing the scanning electron-micrographs and the School of Engineering Science, University of North Wales, Bangor for the use of their stereoscan. I should also like to thank Mr M. C. Bibby for technical assistance and Professor E. G. Gray and Dr W. Sinclair for assistance with the transmission electron-micrographs.
Epidemiological relationships of Trypanosoma brucei stocks from South East Uganda: evidence for different population structures in human infective and non-human infective isolates
Authors: Hide G. , Welburn S. C. , Tait A. , Maudlin I. 
Published: June 2009

SUMMARYThis study represents an analysis of trypanosome strains circulating within a confined location over a short period of time during a sleeping sickness epidemic in S.E. Uganda. A large number of Trypanosoma brucei isolates (88) were collected from a variety of hosts (man, cattle, pigs and tsetse) from villages within a 10 km radius and were analysed for variation in isoenzyme patterns, restriction fragment length polymorphism (RFLP) in repetitive DNA sequences and susceptibility to human serum. The human infective stocks form a clearly distinguishable population when compared with other stocks circulating in the domestic cattle reservoir. The data here support the occurrence of genetic exchange between the cattle stocks while an ‘epidemic’ population structure involving limited genetic exchange is a characteristic of the human infective stocks. Furthermore, it is shown that when both RFLP and isoenzyme analysis are carried out most stocks appear to have individual genotypes. Stocks which were formerly grouped as zymodemes are better considered as a collection of distinct individuals.
The structure and composition of the capsule of Trichinella spiralis in host muscle
Authors: Bruce R. G. 
Published: June 2009

SUMMARYThe results of ultrastructural studies and histochemical tests on the capsule of Trichinella spiralis are given. The capsule wall is shown to consist of two layers, an outer region of tightly compacted fibrils and an inner region of fibrils dispersed through matrix cytoplasm. Histochemical tests show the capsule wall to consist mainly of collagen and cystine. The appearance of the matrix, which is packed with mitochondria, rough endoplasmic reticulum, smooth reticulum and Golgi complexes, together with the histochemical reaction to the five enzymes tested, strongly suggests that the matrix is a region of high metabolic activity. Although there are several very large nuclei in the matrix there is no evidence of cell walls; consequently the matrix is a syncytium.I wish to thank the A.R.C. for financial support while this work was carried out. I should also like to thank Dr D. L. Lee for his advice on many occasions and the late Professor Boyd of the Anatomy Department, University of Cambridge, for the use of the electron microscope in that Department.
Observations on the life-cycle of Toxocara mackerrasae
Authors: Warren E. G. 
Published: June 2009

SUMMARYAn analysis of natural infections of Toxocara mackerrasae in Rattus fuscipes trapped in rain forests in south-eastern Queensland is given and Hydromys chrysogaster is listed as a new host.T. mackerrasae larvae in egg-infected mice are incapable of somatic migration but some complete development to the young adult stage can occur entirely within the alimentary tract. T. mackerrasae is capable, in low numbers, of developing to maturity in experimentally infected Rattus spp.The work was financed by grants from the University of Queensland and the National Health and Medical Research Council of Australia. I wish to thank Professor J. F. A. Sprent for his criticisms and suggestions during the preparation of this text.
Diurnal movement ofHymenolepis diminutain the rat
Authors: Hopkins C. A. 
Published: June 2009

SUMMARYFollowing a 2–5 ml meal containing 2 g (80%) glucose and 30 mg methionine administered by stomach tube at 09.00 h,H. diminutawas found to change its position in the rat's intestine. Usually while the stomach contained food ≤ 45 %, by weight, of the tapeworm lay in the posterior 40 % of the small intestine, after the stomach was empty the reverse was true.The effect of hyperosmotic fluid entering the duodenum was determined by injecting, following laparotomy, varying amounts of 80 % glucose and 1 ml of varying concentrations. A volume ≤ 0-4 ml of 80 % led to the death and expulsion of worms within 7 h, and 1 ml of < 50 % glucose also killed the worms.The expulsion of 15 % of the tapeworms from rats given 2–5 ml hypertonic meal by mouth was correlated with the failure of the stomach in some rats to regulate the stomach emptying. Worms in these rats were found from 4 h onwards in the caecum and large intestine, and by 9 h in the faeces.That the movement of worms, other than those expelled, was not caused by a sub-lethal flux of hyperosmotic fluid was shown by feeding an iso-osmotic meal to rats; the worms moved to a more posterior position during the day, but none was expelled.Single worm infections in rats kept on a normal feeding regime until 07.00 h and then starved throughout the day also showed a posterior migration. Using a method which involved the simultaneous cutting of the small intestine into 5 cm sections, it was possible to show that this movement involved the whole worm, the scolex moving from a mean position 10–15 cm to one 20–25 cm from the stomach, and the terminal proglottid moving from approximately 75 cm to 95 cm from the stomach.Worms in Wistar rats responded similarly to those in SPF CFE (Sprague Dawleys) with the exception that there was some evidence that the stomach emptying of a hyperosmotic meal was better controlled and hence a smaller percentage of the worms were expelled.The results are discussed in relation to diurnal changes in the level of the external site location stimulus which other workers have shown to exist by surgically transplantingH. diminutainto the ileum.The enthusiastic assistance of Miss Helen Stallard, B.Sc., and Miss Patricia Grant is gratefully acknowledged, and financial support from the Medical Research Council, London (Grant No. G967/164/T).
Septata intestinalis frequently isolated from stool of AIDS patients with a new cultivation method
Authors: Van Gool T. , Canning E. U. , Gilis H. , Weerman M. A. Van Den Bergh , Schattenkerk J. K. M. Eeftinck , Dankert J. 
Published: June 2009

SummaryTwo species of microsporidia, Enterocytozoon bieneusi and Septata intestinalis have been reported as intestinal parasites of AIDS patients. In attempts to establish E. bieneusi in vitro, spores were concentrated from stool samples from 4 AIDS patients with biopsy-proven E. bieneusi infections. After sterilization of the concentrate in antibiotic solution, the spores were added to monolayers of RK13 cells grown on the membranes of Transwells. Cultures were established from 7 stool samples from the 4 patients but in every case the species established was S. intestinalis not E. bieneusi. On retrospective examination of the stools, a very small number of spores of a size comparable to that of S. intestinalis was found but this species was not detected in biopsies. Typical septate vacuoles containing Type I tubules were observed in vitro but in contrast to the original description, meronts were intravacuolar and sporogony was mainly disporoblastic. The cultivation system, used for the first time for microsporidia, revealed the presence of unsuspected S. intestinalis infections and indicates that this species may be much more common than hitherto suspected. S. intestinalis has not previously been cultured.
Proteinases of females of the phytoparasiteGlobodera pallida(potato cyst nematode)
Authors: Koritsas V. M. , Atkinson H. J. 
Published: June 2009

SummarySensitive assays capable of detecting proteinases in single females of the phytoparasiteGlobodera pallidahave been developed and used to define the proteinase activity of young adult females. Digestion of the large subunit of the plant protein Rubisco established a pH optimum for the proteinase activity at pH 5·7. The activity was inhibited by the cysteine proteinase inhibitorsp-chloromercuribenzoic acid (PMBA) andp-chloromercurisulphonic acid (PMSA) and stimulated by both cysteine and dithiothreitol (DTT). It was moderately reduced by L-trans-epoxysuccinyl-leucylamido-(4- guanidino) butane (E64) but not by specific inhibitors of serine, aspartate or metallo-proteinases. The activity separated into 3 bands on a non-denaturing gel but only I proteinase of 62 kDa was recovered following a combination of anion-exchange chromatography and affinity chromatography using PMBA. The effect of inhibitors was similar to that reported previously for some of the cysteine proteinase activity recovered fromCaenorhabditis elegansbut is apparently not that for which the corresponding gene has been cloned in this nematode andHaemonchus contortus.The proteinase may have a major role in digestion of dietary protein and so offers an exciting target for future control of this important plant-parasitic nematode.
Immunocytochemical demonstration of peptidergic and serotoninergic components in the enteric nervous system of the roundworm,Ascaris suum(Nematoda, Ascaroidea)
Authors: Brownlee D. J. A. , Fairweather I. , Johnston C. F. , Shaw C. 
Published: June 2009

SUMMARYThe localization and distribution of neuropeptides and an indoleamine (serotonin or 5-hydroxytryptamine) in the enteric nervous system (ENS) of the pig roundworm,Ascaris suum, have been determined by the application of an indirect immunofluorescence technique in conjunction with confocal scanning laser microscopy. Whole-mount preparations of pharyngeal, intestinal and rectal regions were screened with antisera to 23 vertebrate peptides, 2 invertebrate peptides and serotonin (= 5-HT). Positive immunoreactivity (IR) was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), FMRFamide, gastrin and serotonin. The only IR observed in the ENS was that evident in the nerve supply to the pharynx and rectal region; no IR was associated with any region of the intestine. The most extensive patterns of IR occurred with antisera to PYY, FMRFamide and serotonin. In the pharyngeal component of the ENS, IR was evident in the lateral and dorsal longitudinal pharyngeal nerves, pharyngeal commissures, nerve plexus, and associated nerve cells and fibres. In contrast, the distribution of IR to the PP and gastrin antisera was more restricted and displayed a lower intensity of immunostaining. The other component of the ENS, the rectal enteric system, only yielded immunostaining to FMRFamide. The possible role of neuropeptides and serotonin in the nutritional biology of nematodes is discussed.
Sexual development in malarial parasites: gametocyte production, fertility and infectivity to the mosquito vector
Authors: Dearsly A. L. , Sinden R. E. , Self I. A. 
Published: June 2009

SUMMARYUsing cloned lines ofPlasmodium bergheiproducing mixed asexual and sexual (clone 234L) and purely asexual (clone 233L) parasitaemias, the courses of parasitaemia, gametocytogenesis, exflagellation, ookinete productionin vitroand mosquito infectivity have been followed. For clone 234L mosquito infectivity is maximal at day 3 and has ceased by day 6 post-infection. Conversely, gametocytogenesis, exflagellation and ookinete production are at minimal levels at day 3 and rise to peaks between days 10 and 15 of infection (in TO mice infected with blood at mechanical blood passage 3). Sexual potential declines progressively with sustained mechanical passage (up to P14). Gametocyte conversion is highest early in infection and declines exponentially; however, upon each mechanical passage conversion is again raised but decreases more rapidly with succeeding passages. For practical mosquito transmission in the laboratory we consider P8to be the useful limit for mechanical transmission for this parasite clone. Asexual parasite growth (virulence) is more rapid with increased mechanical passage inducing a rapid fall in haematocrit. By P14the course of infection closely parallels that of the purely asexual clone 233L.
Genetically-determined influences on the ability of poor responder mice to respond to immunization againstTrichuris muris
Authors: Else K. J. , Wakelin D. 
Published: June 2009

SUMMARYStrains of mice poorly (B10) or non-responsive (B10.BR) to a primary infection withTrichuris muriswere protected against infection by vaccination with excretory/secretory (E/S) antigen in Complete Freund's Adjuvant (CFA). Protection in these mice was slow to be expressed compared to that in good responder strains. Vaccination boosted the IgG and IgG1 antibody responses to E/S antigen and altered the antigen recognition profiles, three high molecular weight antigens (80–85, 90–95, 105–110 kDa) being recognized by antibodies in sera from vaccinated but not control mice. B10. BR mice which had experienced a patent primary infection could not be protected against challenge infections by vaccination and this was correlated with depressed levels of IgG1, but not total IgG, to E'S antigen early post-challenge compared with vaccinated infected mice which had not seen an adult primary infection. There was also lack of recognition of the three high molecular weight antigens recognized by antibodies in sera from mice infected after vaccination. It is suggested that the rapid development of high levels of IgG1 antibodies, and the recognition of the three high molecular weight antigens, may reflect events that are important in protective immunity. Immunomodulation of host immunity byT. murismay therefore be achieved, at least in part, by the suppression of specific IgG1 levels, the production of an irrelevant IgG isotype and prevention of the recognition of critical antigens.
Biased sex ratios and parasite mating probabilities
Authors: May R. M. , Woolhouse M. E. J. 
Published: June 2009

SummaryAn earlier paper (May, 1977) developed a theoretical framework for exploring the consequences of dioecy for the population dynamics of schistosomes, assuming an unbiased sex ratio. This paper extends the analysis to biased sex ratios, as have been reported in practice. We consider the relationships of the mean number and distribution of worms among hosts, the sex ratio, and the mating system (monogamous or polygamous) to: (i) the female mating probability, Φ the prevalence of mated female worms. Ω: and (iii) the mean number of mated female worms per host, ξ. Among other results, we show how high values of Φ are associated with male-biased sex ratios and polygamous mating; that Ω is independent of the mating system and is relatively unaffected by the sex ratio; and that ξ is maximal for unbiased sex ratios given monogamous mating, and for female-biased sex ratios if mating is polygamous. These results, together with the confounding effects of the mean number and distribution of worms, are described in detail in the main body of the paper.
Frequency of cross-fertilization in the human malaria parasitePlasmodium falciparum
Authors: Ranford-Cartwright L. C. , Balfe P. , Carter R. , Walliker D. 
Published: June 2009

SummaryTwo clones of the human malaria parasitePlasmodium falciparum, denoted 3D7 and HB3, were grownin vitrounder conditions permitting the development of gametocytes. The two clones differ in their allelic forms of two antigen genes MSP1 and MSP2. The alleles can be distinguished as size differences of polymerase chain reaction (PCR) amplified fragments of repetitive regions of each gene. Mosquitoes (Anopheles stephensi) were fed on a mixture of these gametocytes. A total of 128 oocysts was isolated from the midguts of infected mosquitoes from 9 crossing experiments between the clones. DNA extracted from these oocysts was amplified by PCR. Oocysts which contained both alleles of each gene (MSP1 and MSP2) had developed from heterozygotes produced by cross-fertilization events between 3D7 and HB3 gametes. The remaining oocysts contained single alleles of each gene, in parent clone combinations, and these had developed from homozygotes formed by self-fertilizations. The results suggest that gametes in the original mixture fed to mosquitoes had undergone random mating.
Characterization ofMegatrypanumtrypanosomes from European Cervidae
Authors: Böse R. , Petersen K. , Pospichal H. , Buchanan N. , Tait A. 
Published: June 2009

SummaryMegatrypanumtrypanosomes have been isolated from a number of different European Cervidae, but on the basis of morphology it has not been possible to define the species to which these isolates belong. We isolatedTrypanosoma (Megatrypanum) theilerifrom 10 cattle, andMegatrypanumtrypanosomes from 11 fallow deer (Cervus dama), 9 red deer (Cervus elaphus), and 4 roe deer (Capreolus capreolus) by blood culture on a biphasic medium (NNN agar slopes). Trypanosomes were propagated in Schneider's Drosophila medium and characterized by isoenzyme analysis and molecular karyotyping. Isocitrate dehydrogenase and phosphoglucomutase were visualized after starch gel electrophoresis of trypanosome lysates. By cluster analysis of this data all isolates from deer were clearly separated from theT. (M.) theileriisolates from cattle. Isolates from roe deer were different not only fromT. (M.) theileribut also from the other deer isolates. Isolates from fallow deer and red deer were grouped together. Thus, there are probably at least two different species ofMegatrypanumtrypanosomes in the three Cervidae. One parasitizing roe deer, the other, apparently less host specific species, infecting red deer and fallow deer. Separation of the chromosomes ofMegatrypanumtrypanosomes by pulsed-field gradient gel electrophoresis (PFGE) showed that each isolate contained a large number (> 18) of chromosomes ranging in size from 300 to > 2200 kb. The molecular karyotypes were similar for all isolates, although no isolate was identical to another.
The influence of second intermediate host dispersion pattern upon the transmission of cercariae of Echinoparyphium recurvatum (Digenea: Echinostomatidae)
Authors: McCarthy A. M. 
Published: June 2009

SUMMARYTransmission of cercariae of the echinostome digenean Echinoparyphium recurvatum was observed in experimental populations of the second intermediate host snail Lymnaea peregra. Populations of 100 snails were distributed among plastic mesh cages in an infection arena to produce different patterns of host dispersion. Cercarial transmission was investigated in host populations showing three separate patterns of host dispersion; Ideal Regular, Random and Contagious (‘Clumped’). Levels of cercarial transmission in populations showing each type of dispersion pattern were found to be significantly different. The highest rate of cercarial transmission occurred in the contagiously dispersed host population, and the lowest in the randomly dispersed population. Analysis of results from the randomly dispersed population also showed that both the mean percentage prevalence of infection, and also the mean number of cysts recovered per snail, increased significantly with the number of snails per cage. The positive relationship between the mean number of cysts per snail and the number of snails per cage was found to be best described by an exponential function. Chemosensory location of L. peregra snail hosts by E. recurvatum cercariae may provide an explanation for the patterns of cercarial transmission observed.