bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leishmania mexicana mexicana: quantitative analysis of the intracellular cycle
Authors: Doyle P. S. , Engel J. C. , Gam A. A. , Dvorak J. A. 
Published: June 2009

SummaryThe complete intracellular cycle of theLeishmania mexicana mexicanaG. S. strain was quantified in human macrophages and in the mouse IC-21 macrophage line utilizing a culture system that allows the direct observation of individual intracellular parasites. A wide range of pre-replicative lag periods exists, implying that promastigotes may be in any phase of their DNA synthetic cycle when phagocytosed by the macrophage. Amastigotes replicated 2–3 times, after which the host cell died and liberated amastigotes that were taken up by other macrophages and continued to replicate. The mean amastigote population-doubling time in human macrophages (17.5 h) was not statistically different from promastigotes growing in axenic culture (16.4 h), but was nearly 2-fold less than amastigotes growing in mouse-derived IC-21 macrophages (33.7 h). These observations are markedly different from cover-glass culture assays ofLeishmania-macrophageinteractions and provide an unambiguous description of the intracellular cycle ofLeishmania mexicanamexicana.
A monoclonal antibody-derived antigen ofBabesia divergens: characterization and investigation of its ability to protect gerbils against virulent homologous challenge
Authors: Winger C. M. , Canning E. U. , Culverhouse J. D. 
Published: June 2009

SummaryABabesia divergensmerozoite antigen was purified by affinity chromatography using a monoclonal antibody. Silver staining of SDS-PAGE gels revealed 2 bands of Mr50–60 kDa and Mr24–29. It is proposed that the Mr24–29 kDa band represents the native protein and that it is complexed, perhaps as a dimer or perhaps to host protein to give the Mr50–60 kDa band. Peptide analysis of the antigen followed by Western blotting with the monoclonal antibody revealed only an Mr20–24 kDa band. After affinity purification the antigen was precipitated with acetone and inoculated subcutaneously, together with complete Freund's adjuvant, into gerbils. Two inoculations were given 3 weeks apart, after which the immunized animals and a group of control animals were challenged with 5 × parasitized red cells from a virulent microaerophilus stationary phase (MASP) culture of an homologous strain ofB. divergens. Parasitaemias rose rapidly in control animals and all were dead by the fifth day. Two of the vaccinated animals survived the challenge. Parasitaemias in the remaining two rose slowly but both animals succumbed on the seventh day. Western blotting of merozoites and of the purified antigen, using sera from the surviving animals showed strong reactivity with the Mr24–29 kDa band.
Variable generation of specific acquired resistance in CBA/Ca mice chronically infected with schistosomiasis mansoni
Authors: Delgado V. S. , Mclaren D. J. 
Published: June 2009

SummaryNaive CBA/Ca mice and CBA/Ca mice infected 12 weeks previously with 20 normal cercariae ofSchistosoma mansoniwere challenged percutaneously with isotopically labelled parasites. Challenge worm migration was followed, in 5 separate experiments, by means of compressed organ autoradiography. In three experiments, 43.1 % of challenge parasites did not arrive in the lungs of infected mice on day 6 as compared to 7.7 % in naive controls, thereby indicating that pre-lung sites constitute the first barrier in resistance to reinfection. A further 15% of the challenge worm burden was lost in the lungs or en route to the liver in the immune animals, and portal perfusion revealed that 25.4% of the challenge was lost in the liver. Two other experiments revealed no comparable phases of pre-liver attrition however; instead resistance was only evident at final perfusion on days 28 or 35. These data reveal the variable generation of specific acquired immunity in mice harbouring a chronic schistosome infection and thus clarify current discrepancies in the literature. The results are discussed in relation to documented evidence for the nature of specific and non-specific immune mechanisms reported to operate at different sites in the infection model of schistosomiasis mansoni.
Effects of potential inhibitors on Brugia pahangi in vitro: macrofilaricidal action and inhibition of microfilarial production
Authors: Barker G. C. , Mercer J. G. , Svoboda J. A. , Thompson M. J. , Rees H. H. , Howells R. E. 
Published: June 2009

SummaryA series of compounds that apparently disrupt hormonally regulated processes in insects have been examined for effects on the viability and microfilarial production of adult Brugia pahangi cultured in vitro. The azasteroids, 25-azacoprostane and 25-azacholestane, inhibited the production of microfilariae at 5 ppm, the former also exhibiting macrofilaricidal activity at this concentration. The brassinosteroids examined inhibited microfilarial production at 5 ppm but did not affect worm viability. Azadirachtin also proved to be a significant inhibitor of microfilarial release without effect on worm motility or viability. Of all the compounds tested, the non-steroidal amines appeared to be the most promising as potential filaricides, several of them proving to be macrofilaricidal at 1 ppm and affecting microfilarial production at even lower concentrations.
Synthesis and degradation of glycogen by Schistosoma mansoni worms in vitro
Authors: Tielens A. G. M. , Celik C. , Heuvel J. M. Van Den , Elfring R. H. , Bergh S. G. Van Den 
Published: June 2009

SummaryThe glycogen stores of adult Schistosoma mansoni worms could be labelled by incubation of the worms, after an initial reduction of their glycogen content, in the presence of [6-14C]glucose. Subsequent breakdown of the labelled glycogen by the parasite revealed that glycogen was degraded to lactate and carbon dioxide. The degradation of glycogen, as compared to that of glucose, resulted in slightly different ratios of these two end-products. This indicates that glycogen breakdown did not replace glucose breakdown to the same extent in all cells and that Krebs-cycle activity was not uniformly distributed throughout the cells of this parasite. Both fructose and mannose could replace glucose as an energy source and the rate of glycogen synthesis from either of these two carbohydrates was higher than from glucose. No indications for glyconeogenesis from C3-units were found. Glycogen metabolism of S. mansoni was not influenced by hormones of the mammalian host. It is regulated by the external glucose concentration and by the level of the endogenous glycogen stores. Studies on paired and unpaired worms showed that no interaction between male and female was necessary for the synthesis of glycogen by female worms.
Transmission of taeniid tapeworm eggs via blowflies to intermediate hosts
Authors: Lawson J. R. , Gemmell M. A. 
Published: June 2009

SummaryExperiments showed that dead blowflies containing eggs of Taenia hydatigena can transmit infection if ingested by lambs during grazing. Rabbits became infected with T. pisiformis after grazing grass exposed to blowflies that had been in contact with dog faeces containing the eggs of this parasite. When captive blowflies were exposed first to dog faeces containing proglottids of T. hydatigena and then to cooked meat, 100% of pigs fed on this meat became infected. The experiments are intended to model the transmission dynamics that result in human larval tapeworm infections. The implications of the results to the epidemiology of human hydatid diseases caused by Echinococcus granulosus and E. multilocularis as well as of T. solium cysticercosis are discussed.
Schistosoma japonicum: some parameters affecting the development of protective immunity induced by a cryopreserved, irradiated schistosomula vaccine in guinea-pigs
Authors: Xu S. , Shi F. , Wu H. 
Published: June 2009

SUMMARYExperiments were conducted in guinea-pigs to elucidate the parameters affecting the development of protective immunity against Schistosoma japonicum induced by a cryopreserved, irradiated schistosomula vaccine such as the number of immunizations, route of injection and the use of adjuvants. Results obtained indicated that the cryopreserved, irradiated schistosomula vaccine was effective by either intradermal or intramuscular injection. One intradermal injection with BCG adjuvant resulted in an average worm reduction of 50·24%, only a little lower than that of a non-cryopreserved, irradiated vaccine, 53·55%, with no statistically significant difference between the two. By intramuscular injection the worm reduction was lower (max. 40%) whether given with or without adjuvants or in 1 or 2 injections.
Temperature-dependent reproduction and survival ofGyrodactylus salarisMalmberg, 1957 (Platyhelminthes: Monogenea) on Atlantic salmon (Salmo salarL.)
Authors: Jansen P. A. , Bakke T. A. 
Published: June 2009

SUMMARYThe relationship of survival and reproduction ofGyrodactylus salarisMalmberg on the Atlantic salmon (Salmo salar) to water temperature (2·5–19·0 °C), was studied on the basis of temporal sequence of births and age at death of individual parasites on isolated salmon, and of infrapopulation growth on isolated and grouped salmon. Mean life-span of the parasite was negatively correlated with water temperature: 33·7 days at 2·5 °C and 4·5 days at 19·0 °C. The average number of offspring per parasite peaked between 6·5 and 13·0 °C, and was approximately 2·4 at these two temperatures. Both the period between the successive births of the offspring (max 4) and the estimated generation time were negatively correlated with temperature. The innate capacity for increase (rm) was positively correlated with temperature: from 0·02 (/parasite/day) at 2·5 °C to 0·22 (/parasite/day) at 19·0 °C. Growth of the infrapopulations was positively correlated with water temperature and was higher on isolated fish than on grouped fish, though less than the potential parasite population growth estimated fromrm. In the infrapopulations the mean intensity of parasites continued to increase throughout all the experiments on both isolated fish and on grouped fish.
The inhibition ofPlasmodium falciparumgrowthin vitroby sera from mice infected with malaria or treated with TNF
Authors: Butcher G. A. , Clark I. A. 
Published: June 2009

SUMMARYDespite some years of enquiry, the mechanism that leads to intra-erythrocytic death of malarial parasites during the host's response to infection has not been elucidated. We report here that serum from mice undergoing a successful immune response toPlasmodium chabaudidoes not inhibitPlasmodium falciparumunless thePl. chabaudiis virulent enough to rise to at least 50% parasitaemia and to cause illness. This appears to be true of the 556 KA and DS strains ofPl chabaudi, and also other murine malaria parasites. In mice infected withPl. chabaudi556 KA inhibitory activity coincided with the presence of TNF in their serum. Exogenous TNF generated inhibitory activity in the serum of mice only if the animals were pretreated withProprionobacterium acnes, implying a role for activated macrophages downstream from TNF in this process. The difference in inhibitory activity againstPl. falciparumin serum from mice infected withPl. chabaudiof more or less virulence may be one of degree. Alternatively two distinct mechanisms may operate, the second coming into operation only in ill mice, with higher parasite burdens.
Association between circulating antigen and parasite load in a model filarial system,Acanthocheilonema viteaein jirds
Authors: Harnett W. , Worms M. J. , Grainger M. , Pyke S. D. M. , Parkhouse R. M. E. 
Published: June 2009

SUMMARYJirds (Meriones libycus) were infected with various numbers ofAcanthocheilonema viteaeL3 stage parasites. During the course of the ensuing 16 weeks, blood samples were collected at 2 weekly intervals and the amount of the major parasite excretory–secretory product (E–S 62) and antibodies directed against it measured. After 16 weeks, animals were sacrificed and the size of the mature worm burden established. In spite of interaction between E–S 62 and host antibody, a statistically significant relationship was found to exist between the amount of E–S 62 present in the bloodstream and the size of the parasite load. It is suggested that the detectable antigen level is more influenced by the size of the worm burden than the presence of antibody and that antibody is only likely to affect adversely antigen measurement in situations where the amount released is relatively low. Examples of this are early in infection and in low-level infections. These ideas are discussed in relation to the development and assessment of serological assays which attempt to predict parasite burden in human filarial infections.
The in vitro transformation of the miracidium to the mother sporocyst of Schistosoma margrebowiei; changes in the parasite surface and implications for interactions with snail plasma factors
Authors: Daniel B. E. , Preston T. M. , Southgate V. R. 
Published: June 2009

SUMMARYThe in vitro transformation of the miracidium to the mother sporocyst of Schistosoma margrebowiei was initiated by placing the miracidium in mammalian physiological saline. The transformation occurs in stages: the cilia cease beating; the ciliated plates become detached from the intercellular ridges and underlying muscle layers; the intercellular ridges spread over the body surface eventually forming a new tegument; the sporocyst changes from an ovoid to a tubular shape in about 48 h at room temperature. The surfaces of the miracidium, sporocyst and cercaria of S. margrebowiei display stage-specific carbohydrates on their surfaces as indicated by lectin staining. Ricin120 stains the cilia alone of the miracidium whereas peanut agglutinin stains the larval surface except for the cilia. The intercellular ridges of the miracidium stain with concanavalin A and wheat germ agglutinin, and these lectins stain the entire surface of the mature mother sporocyst. The cercaria is the only larval stage which stains positively with asparagus pea lectin. Bulinus nasutus is incompatible with Schistosoma margrebowiei; the haemolymph of this snail contains an agglutinin which agglutinates a wide variety of mammalian erythrocytes including those of human ABO blood groups. The haemagglutinin titre of B. nasutus plasma is reduced after incubation with miracidia of S. margrebowiei indicating that the agglutinin is absorbed onto the surface of this larval stage but not that of the mother sporocyst or cercaria. The possible roles of agglutinins in host–parasite interactions together with the significance of the differences in the surface carbohydrates of the larval stages are discussed.
Trypanosoma cruziglutathione-binding proteins: immunogenicity during human and experimental Chagas' disease
Authors: Plumas-Marty B. , Verwaerde C. , Loyens M. , Velge P. , Taibi A. , Cesbron M. F. , Capron A. , Ouaissi M. A. 
Published: June 2009

SUMMARYFollowing purification by affinity chromatography, three glutathione-binding proteins (TcGBP) of 45, 30, and 25 kDa were co-purified fromTrypanosoma cruziepimastigotes. Using 1-chloro-2,4 dinitrobenzene as substrate, a glutathione S-transferase activity of 70 nmol/min/mg of proteins was detected in the GSH binding fraction. An increased expression of TcGBP and total GST activity was observed upon incubation of parasites with phenobarbital, which is an inducer of GST synthesis. Immunofluorescence and electron microscopic experiments demonstrated that TcGBP were expressed by all developmental stages of the parasite, including infective forms. The expression of these proteins by intracellular dividing amastigotes could be in favour of a potential defensive role of these molecules against host attack. Results obtained by immunoprecipitation ofin vitrotranslation products using anti-TcGBP antisera suggested that these three polypeptides are not glycosylated. In addition, antibodies directed against the TcGBP were found in a high proportion ofT. cruzi-infected chronic chagasic patients' sera and in sera of chronically infected BALB/c mice. In contrast, acute chagasic patients' sera and acute-phase mouse sera were found to be poorly reactive with these proteins. Our results identify a new class of potential target antigens, which may be essential for the development ofT. cruziin its host. Their protective role in experimental models deserves to be investigated.
Genetic variation in Trypanosoma brucei and the epidemiology of sleeping sickness in the Lambwe Valley, Kenya
Authors: Cibulskis R. E. 
Published: June 2009

SUMMARYA contingency table approach was used to explore the influence of location, host species and time on the genetic composition of a Trypanosoma brucei population in Lambwe Valley, Kenya. Significant differences in zymodeme frequencies were noticed over comparatively short geographical distances suggesting that transmission of T. brucei is somewhat localized. A significant association was observed between zymodeme and the mammalian host from which T. brucei was derived. The association was consistent in different localities in Lambwe valley and remained stable for at least 32 months. These observations indicate that zymodemes are adapted to different host species and that genetic exchange has not disrupted host associations over this time-scale. A major change in the composition of the T. brucei population during a sleeping sickness outbreak in 1980 was confirmed. But while new zymodemes emerged, a decline in overall diversity was noted during times of high sleeping sickness incidence. The results can be explained by selection of T. brucei zymodemes for particular transmission cycles. Although it is not necessary to invoke genetic exchange, sex may help T. brucei to adapt to changes in selection pressures. Such a hypothesis helps to explain why T. brucei appears largely clonal in the short term, even though population studies indicate that sex is responsible for much genetic diversity in the long term. It also explains why neighbouring populations of T. brucei are composed of a different range of zymodemes formed from the same alleles. Such a view implies that genetic exchange has an important role in the microevolution of T. brucei populations.
The laboratory maintenance of Sanguinicola inermis Plehn, 1905 (Digenea: Sanguinicolidae)
Authors: Kirk R. S. , Lewis J. W. 
Published: June 2009

SUMMARYMethodology is described for the laboratory maintenance of the life-cycle of Sanguinicola inermis, using common carp (Cyprinus carpio) as the definitive host and Lymnaea peregra as the intermediate host. Lymnaea auricularia was also infected but is not considered to be a suitable laboratory host. Tench (Tinca tinca) were susceptible to infection at high cercarial doses but subsequent infection rates were low. Goldfish (Carassius auratus) and Lymnaea stagnalis were refractory to laboratory infection.
Megasomes as the targets of leucine methyl ester inLeishmania amazonensisamastigotes
Authors: Antoine J.-C. , Jouanne Colette , Ryter Antoinette 
Published: June 2009

SUMMARYCertain L-amino acid esters, such as L-leucine methyl ester (Leu-OMe), can kill intracellular and isolatedLeishmania amazonensisamastigotes. Killing appears to involve ester trapping and hydrolysis within an acidified parasite compartment (M. Rabinovitch and S. C. Alfieri, 1987,Brazilian Journal of Medical and Biological Research20, 665–74). We show here by acid phosphatase light microscopic cytochemistry and by ultrastructural morphometry that megasomes, lysosome-like amastigote organelles, are the putative parasite targets of Leu-OMe. This conclusion is supported by the following observations, (a) Control amastigotes displayed a string of electron-dense, acid phosphatase-positive megasomes mostly located in the cellular poles opposite the flagellar pockets. Incubation of the amastigotes with Leu-OMe resulted in concentration-dependent swelling and fusion of the organelles as well as decreased electron density of the internal contents. These changes, which preceded parasite disruption, were followed by the progressive loss of parasite viability and the release of acid phosphatase activity into the medium, (b) Incubation of the amastigotes with L-isoleucine methyl ester, a non-leishmanicidal compound, induced only moderate fusion of the megasomes. (c) Pre-incubation of the parasites with the proteinase inhibitors antipain and chymostatin, previously shown to confer protection from Leu-OMe toxicity, nearly completely prevented the morphological changes of megasomes. (d) Exposure of amastigotes to tryptophanamide (Trp-NH2), the leishmanicidal activity of which is not reduced by antipain and chymostatin, did not result in swelling and fusion of the megasomes. This last finding suggests that different mechanisms underlie the destruction of amastigotes by Trp-NH2 and Leu-OMe. Overall, the results are compatible with the hypothesis that Leu-OMe and other amino acid esters are trapped and hydrolysed within megasomes.
Repetitive DNA and hybridization patterns demonstrate extensive variability between the sibling species Globodera rostochiensis and G. pallida
Authors: De Jong A. J. , Bakker J. , Roos M. , Gommers F. J. 
Published: June 2009

SUMMARYA method is described for the isolation of high molecular weight DNA from females of potato cyst nematodes. Restriction enzyme analyses of repetitive DNA revealed 30 bands specific for Globodera rostochiensis and 8 bands specific for G. pallida. None of the repetitive DNA bands resolved was common to both species. Hybridization patterns, obtained with a DrosophilaβJ-tubulin probe, revealed 4 common bands, 3 bands specific for G. rostochiensis and 12 bands specific for G. pallida.
Expression of hybrid malaria antigens in insect cells and their engineering for correct folding and secretion
Authors: Murphy V.F. , Rowan W.C. , Page M.J. , Holder A.A. 
Published: June 2009

SUMMARYHybrid proteins containing selected regions of the major surface antigens of the sporozoite and merozoite stages of Plasmodium falciparum were expressed in insect cells using baculovirus vectors. A recombinant protein containing the signal peptide from the precursor to the major merozoite surface antigens (PMMSA) fused to a fragment from the carboxy (C) terminus of the same gene was recognized by monoclonal antibodies specific for reduction-sensitive conformational epitopes within the C-terminal fragment, suggesting that correct disulphide cross-linking of cysteine residues within this region had occurred. Addition of 26 copies of the tetrapeptide repeat from the circumsporozoite protein (CSP) resulted in a protein recognized by anti-CSP antiserum as well as the conformation specific inonoclonal antibodies. Deletion of the C-terminal putative anchor sequence from both proteins resulted in secretion of protein in a fully soluble form antigenically indistinguishable from the anchor containing products. Correct conformation was not observed when the proteins were expressed as polyhedrin fusions without the signal peptide. These data indicate that the PMMSA signal peptide is recognized in insect cells and that correct assembly of disulphide cross-links is dependent upon targeting the protein to the endoplasmic reticulum.
A basis to extend the proof of migration routes of immature parasites inside hosts: estimated time of arrival of Nippostrongylus brasiliensis and Strongyloides ratti in the gut of the rat
Authors: Tindall N. R. , Wilson P. A. G. 
Published: June 2009

SUMMARYThe time taken for larvae of Nippostrongylus brasiliensis and a homogonic strain of Strongyloides ratti to complete their migration from the skin surface to the small intestine of the rat was estimated by a new method in which a mirror image of arrival times was created by counting mature parasites at day 8 (N. brasiliensis) or day 5 (S. ratti) in the intestines of rats that had received a single pulse of morantel tartrate by stomach tube at different times starting 10 h after skin application of exact doses of infective larvae. It was confirmed that the effect of the drug was confined to parasites in the gut, so that the kinetics of migration were unperturbed.