bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxicity of cyclosporin A (CsA) against developmental stages of Schistosoma mansoni in mice
Authors: Munro G. H. , McLaren D. J. 
Published: June 2009

SummaryIt has been shown elsewhere that the immunosuppressive drug cyclosporin A (CsA) exerts profound schistosomicidal activity when given to infected mice via a multiple administration regime. We show here that a single treatment regime also effects significant reductions in worm burden. Moreover, drug efficacy is maintained at CsA concentrations shown to be subimmunosuppressive in other systems. Subcutaneous treatment effected higher levels of schistosomicidal activity than intraperitoneal or oral treatment, irrespective of whether the drug was given prior to or during infection. Topical application of CsA to the skin site of cercarial penetration, prior to infection resulted in no reduction in worm burden. Systemic release of CsA from a slowly adsorbed, oil-based drug-vehicle combination effected greater levels of killing than when CsA was dissolved in an aqueous drug vehicle. All developmental stages of Schistosoma mansoni were susceptible to killing by a single dose of CsA but, in the case of liver-stage worms, an increased concentration of drug and a longer period between treatment and portal perfusion were needed for killing to be measurable as a reduction in worm numbers.
Polyclonal activation of B lymphocytes during experimental infection withSchistosoma mansoni
Authors: Lopes L. M. , Pereira M. A. C. , Gerken S. E. , Vaz N. 
Published: June 2009

SummaryA significant polyclonal activation of B lymphocytes was observed during experimental infection of C57BL/10J mice withSchistosoma mansoni. The isotypic pattern of this expansion, assessed by the Protein-A plaque-forming cell method, was compared with and found to differ from those occurring after infection byTrypanosoma cruzior injection of bacterial LPS. In the infection ofS. mansonian early expansion of most immunoglobulin isotypes occurs together with a late, sustained expansion of IgG1-secreting cells. High levels of polyclonal B cell activation were observed after adoptive transfer of spleen cells from infected mice to isogenic recipients pre-treated with hydroxyurea.
Honey bee mortality due to tracheal mite parasitism
Authors: Royce L. A. , Rossignol P. A. 
Published: June 2009

SummaryWe demonstrate, by truncating the expected negative binomial distribution, that the tracheal mite parasite, Acarapis woodi, causes mortality in the Europen honey bee, Apis mellifera, but, that this mortality can be documented only during periods of low mite densities (mites per bee). At high mite densities, this technique no longer reveals mite-induced mortality. We suggest that this paradox results from a reduction in the mortality threshold at high mite densities, concealing mortality from our truncation procedures. Longitudinal comparisons of hive and forager bee cohorts, nevertheless, suggests mortality at all levels of infestation. We propose that persistent parasitism overcomes a colony's ability to compensate for losses, leading to its sudden decline and death.
Oxytetracycline inhibition of mitochondrial protein synthesis in bovine lymphocytes infected withTheileria parvaor stimulated by mitogen
Authors: Spooner P. R. 
Published: June 2009

SUMMARYOxytetracycline (OTC) significantly inhibited cytochrome c oxidase activity in bovine lymphocytes infected withTheileria parvaand in uninfected mitogen-stimulated lymphocytes. The inhibitory effect was detectedin vitrowithin 24 h of treatment with drug concentrations as low as 1 µg/ml. Following mitogen stimulation of lymphocytes, concentrations of 3 and 10 µg/ml OTC completely inhibited an increase in cytochrome c oxidase activity for 48–72 h. This inhibitory activity was considered to be due to a direct effect on lymphoblast mitochondrial protein synthesis. As a consequence, adenosine triphosphate activity was significantly reduced in lymphocytes stimulated either by infection withT. parvasporozoites or by mitogen and then treated with OTC. The results also indicated that parasite mitochondrial protein synthesis was inhibited by OTC. The activity of OTC reported in this study could explain the suppression of disease following ‘infection and treatment’ immunization against East Coast fever and thein vitrodrug-inhibition of schizont development.
Effects of three anthelmintics on the tegument ofHymenolepis fraterna(Cestoda)
Authors: Stoitsova S. R. , Gorchilova L. N. , Daněk J. 
Published: June 2009

SUMMARYThein vivoeffects of the anthelmintics taenifugin, VÚFB 14170 and VÚFB 15269 on the tegument ofHymenolepis fraternahave been examined by SEM, TEM and cytochemistry. The drugs were given toH. fraterna-infected mice on the 14th day post-infection in a single oral dose of 150, 200 and 200 mg/kg, respectively. By 72 h post-treatment, the drug-induced pathomorphological changes in the tegument indicated that all three drugs had a significant effect. Changes were most pronounced on the brush border and in the intercellular material. On the apical surface, there was blebbing as well as accumulation of membrane fragments over the microthrix tips and erosion of the brush border. The intercellular material was changed in structure, showing increased electron density in some areas and oedema of the intercellular spaces in other areas. There were also fractures of the tegument of variable depth, sometimes reaching to the parenchyma. These results suggest altered tegumental integrity and, occasionally, complete disruption of the selective permeability barrier created by the normal tegument. This suggestion is further supported by the penetration of ruthenium red into some tegumental areas and its distribution into the intercellular spaces, down to the parenchyma. The intrategumental lysosomes also appeared to be significantly activated. There was evidence of autophagy in both distal cytoplasm and tegumental cells. Mature and gravid proglottides were more susceptible to drug damage than those in the anterior strobila and neck.
The anti-leishmanial activity of dipeptide esters onLeishmania amazonensisamastigotes
Authors: Ramazeilles C. , Juliano L. , Chagas J. R. , Rabinovitch M. 
Published: June 2009

SUMMARYL-Amino acid esters, such as L-Leu-OMe, killLeishmania amazonensisamastigotes by a mechanism which appears to involve ester hydrolysis by cysteine proteinases located in the parasite megasomes. We have examined the killing of isolated amastigotes by L-dipeptide esters and derived some structure-activity correlations. Toxicity of the compounds for the parasites was measured by a tetrazolium (MTT) reduction assay. The results show that active dipeptide esters contained at least I hydrophobic amino acid (Leu, Ile, Val, Phe or Trp). The activity of homodipeptide methyl esters depended on the nature of the amino acid, as indicated by the following series: Phe-Phe-OMe < Val-Val-OMe < Leu-Leu-OMe < Trp-Trp-OMe < Ile-Ile-OMe. The nature of the amino acids in Leu-X-OMe and X-Leu-OMe was relatively unimportant when X was Phe, Trp or Val. However, when X was Ala or Gly, Leu-X-OMe was several-fold more active than X-Leu-OMe.
Dynamic changes of DNA sequences in Schistosoma mansoni in the course of development
Authors: Nara T. , Iwamura Y. , Tanaka M. , Irie Y. , Yasuraoka K. 
Published: June 2009

SUMMARYDeletion and/or amplification of DNA sequences in Schistosoma mansoni were demonstrated by Southern blot analysis. Total cellular DNAs and genomic clones derived from S. mansoni miracidia, adult males and females were used as probes. EndonucleaseBamHI-restricted DNAs from miracidia, adult males and females of both S. mansoni and S. japonicum were reacted to each probe. Hybridization with a total cellular DNA from S. mansoni miracidia as a probe showed elimination of signals in S. mansoni adults. On the other hand, blot analysis using a total cellular DNA from S. mansoni adult males as a probe revealed elimination of hybridization signals in S. mansoni miracidia.Hybridization with a clone SmE15 DNA from S. mansoni miracidia as a probe showed no signal in the DNAs from 5. mansoni adults, indicating these sequences deleted in adults. Hybridization experiments using the probes SmF25 and SmM51 which are 13 and 2-2 kb fragments cloned from S. mansoni adult females and males respectively, demonstrated no signal to DNA from S. mansoni miracidia.Our data suggested the existence of stage-specific DNA sequences in 5. mansoni. We propose a model for multiple-step rearrangement of DNA sequences in S. mansoni during the course of development.
Models to assess the potential ofCapillaria hepaticato control population outbreaks of house mice
Authors: McCallum H. I. , Singleton G. R. 
Published: June 2009

SUMMARYPopulation outbreaks of house mice (Mus domesticus) occur periodically in the wheatlands of southeastern Australia. This paper uses mathematical models to assist in the evaluation of the potential of a nematode,Capillaria hepatica, as a biological control agent to reduce the severity of these ‘plagues’.C. hepaticais unique amongst helminths of mammals in that its eggs are released only upon the death of an infected host. The major goal of the modelling in this paper is to determine the impact of this feature on the population dynamics of the host-parasite interaction. Simple differential equation models are used to examine the general properties of the system and determine which population parameters are most crucial to the outcome of the interaction. These models are supplemented by age-structured models which investigate the initial behaviour of the system after introduction of the parasite. The necessity of host death for transmission is a strongly destabilizing factor, suggesting thatC. hepaticacannot regulate most populations stably in the absence of strong resource limitation, although it has the potential to depress mouse populations below infection-free levels. AlthoughC. hepaticainfluences mouse fecundity at lower burdens than it affects mortality, the age-structured models show that parasite-induced host death cannot be neglected. Because transmission requires host death, the parasite life-cycle operates on a time-scale similar to that of the hosts, and introduction of the parasite as early as possible in the development period of an outbreak will therefore be necessary to achieve substantial reductions in plague intensity.
Immunological realtionships during primary infection withHeligmosomides polygyrus(Nematospiroides dubius): expulsion of adult worms from fast responder syngeneic and hybrid strains of mice
Authors: Wahid F. N. , Robinson M. , Behnke J. M 
Published: June 2009

SUMMARYThe time-course of low and high intensity primary infections withHeligmosomoides polygyruswas monitored in SJL and SWR mice, both of which usually expel worms within 7 weeks of larval administration. Worm expulsion in these strains was not dependent on the intensity of infection, with low and high intensity worm burdens being lost within the same period of time. The ability to expel worms rapidly was inherited in a dominant manner in F1offspring of SJL or SWR mice mated with C57Bl10mice; the latter being a strain in which no loss of worms was evident within 10 weeks of infection. However, neither (SJL × C57Bl10)F1nor (SWR × C57Bl10)F1mice expelled worms as rapidly as the parental SJL and SWR strains. (SWR × B10G)F1[H-2q] mice eliminated worms faster than (SWR × C57Bl10)F1[H-2bq], suggesting that the b haplotype had a moderating influence on the expulsion process. In fact (SWR × B10G)F1mice showed a significant reduction in worm burdens by week 4 but by weeks 6–8 the rate of worm loss had slowed considerably. In contrast, SJL and SWR mice, whilst initiating rejection slightly later, (after week 4) expelled all worms within the following 2 weeks. Thus two distinct patterns of response were observed among the fast responder strains as exemplified by SWR and SJL mice on the one hand and (SWR × B10G)F1on the other. Our results support the hypothesis that the course of a primary infection withH. polygyrusis influenced by multiple host gene loci, some of which are encoded within the MHC. SJL and SWR mice probably have similar if not identical gene combinations at loci which determine a fast responder phenotype, distinguishing them from the other mouse strains which have been studied.
Differences in numbers and inequalities in mass and fecundity during the egg-producing period for Raphidascaris acus (Nematoda: Anisakidae)
Authors: Szalai A. J. , Dick T. A. 
Published: June 2009

SUMMARYMaturity, mass and sex were determined for individual Raphidascaris acus from northern pike, Esox lucius from Dauphin Lake, Manitoba. Length, width and total fecundity of female worms; seasonal changes in worm numbers, growth and maturity; and inequalities in mass and fecundity were quantified for 8 sample periods between April and September. Recruitment of R. acus is most rapid in early spring and continues throughout summer. An accumulation of larvae over winter leads to a peak in the number of gravid worms in spring, while increased feeding by post-spawning pike on yellow perch, Perca fluviatilis, leads to lower levels of gravid worms throughout summer and early autumn. Gravid worms found in spring versus summer were similar with respect to all measured variables and do not appear to be from genetically distinct populations. The strength of the correlation between fecundity and mass for worms was variable between pike and between sample periods, and only weakly correlated when the data were pooled. Much of this variation could be attributed to continued growth of gravid worms after maturation. Worms found in June were smaller, less fecund and less variable and inequalities in mass and fecundity measured using Gini coefficients (GCs) and Lorenz curves (LCs) were most similar at this time. For all other sample periods inequality in fecundity was greater than the corresponding value for mass. Similarity between GCs based on mass and fecundity was maximum when the coefficient of variation (C.V.) for mass was greater than the corresponding C.V. for fecundity. These observations suggest that one must be cautious when applying GCs and LCs to the analysis of parasite populations.
Responses to larvalTaenia taeniaeformisin mice with severe combined immunodeficiency (scid)
Authors: Ishiwata K. , Oku Y. , Ito M. , Kamiya M. 
Published: June 2009

SUMMARYResponses toTaenia taeniaeformisinfection were studied in mice with severe combined immunodeficiency (scid), which lack functional T and B lymphocytes. In the early phase of infection, accumulation of polymorphonuclear leucocytes (PML) occurred around the larvae in the liver ofscidmice and their immunocompetent counterparts, C.B-17, (a BALB/c strain, genetically resistant to this parasite). PML accumulation continued until encapsulation of developing larvae by fibroblasts (14 days p.i.), and subsequent fibrosis resulted in granuloma formation. No infiltration of eosinophils or macrophages around larvae was observed inscidmice prior to granuloma formation, while in C.B-17 mice infiltration was observed as early as 5 days p.i., when specific antibodies could not be detected in the circulation. Most larvae were destroyed by 14 days p.i. in C.B-17 mice. Inscidmice the larvae survived but the host capsules (cysts) were thin and most contained blood at 42 days p.i. In these cysts, inflammatory cells were observed on the larval surface and in invaded parasite tissue. Hepatocyte coagulation necrosis adjacent to larvae was commonly found in C.B-17 mice by 5 days p.i., while it did not occur inscidmice throughout these experiments. These results suggest that in host responses to larvalT. taeniaeformis, PML accumulation and encapsulation by fibrosis are T and B cell independent, while eosinophil and macrophage infiltration, as well as resistance to infection, are T and/or B cell dependent. Additionally, there may be an association between host cell necrosis around larvae and T and/or B cell responses.
Isolation and characterization of polysomes from Trypanosoma brucei
Authors: Cordingley J. S. , Turner M. J. 
Published: June 2009

SUMMARYThe isolation of polysomes in bulk from bloodstream forms of Trypanosoma brucei is described. The polysomes are active in in vitro protein synthesis in the presence or absence of initiation inhibitors. Nascent variant surface antigen (VSA) has been detected on these polysomes using purified radio-iodinated antibody. EDTA-induced ribosomal sub-units and their large rRNA's are characterized. The 26S rRNA is nicked to produce 2 molecules which are both smaller than the 195 rRNA of the small sub-unit which is larger than that found in the majority of eukaryotic small sub-units.
Reactivity of anti-tegument monoclonal antibodies with target epitopes in different worm tissues and developmental stages ofSchistosoma mansoni
Authors: Riengrojpitak Suda , Vojvodic Maria , Boot C. , Wilson R. A. 
Published: June 2009

SUMMARYSixteen monoclonal antibodies (MABs) were selected for their reactivity with adult schistosome tegument. The distribution of target epitopes in different tissues of the adult and in various developmental stages was investigated by indirect immunofluorescence. The distinct patterns of reactivity of the MABs permitted their classification into 9 groups. The distribution of epitopes in larvae, particularly 3 h schistosomula, generally mirrored that in adults. A change in distribution of epitopes coincided with transformation from cercaria to schistosomulum providing a marker for this process. Two MABs reacted with surface membranes of intact cercariae, and 5 with the surfaces of intact 3 h schistosomula. The target epitopes of these 5 MABs were present in the tegument of adults, but not accessible externally. These observations suggest masking of antigens, not shedding, in the course of development. Indeed, no MAB reacted with intact lung or liver worms unless they were damaged. Three MABs reacted with membranes of the tegument and most other tissues, implying properties in common. Evidence for shared functions between epithelia was provided by the reactivity of 2 MABs with the tegument and protonephridia. Eight MABs bound both to the tegument and its cell bodies. Since the latter contains the machinery for protein synthesis, it is difficult to explain why 5 MABs bound to the tegument alone. Little cross-reactivity was found with the tissues of the tapewormHymenolepis, rather more with the closely relatedSchistosoma japonicum. It was concluded that tegument antigens are to a degree tissue specific but definitely not stage specific.
Role of hypochlorous acid inTrypanosoma musculikilling by phagocytes
Authors: Vincendeau P. , Daulouède S. , Veyret B. 
Published: June 2009

SUMMARYTrypanosoma musculiare readily killed when phagocytosed by mononuclear phagocytes but the nature of the mediators of this cytotoxicity is unclear. Among the most potent mediators are oxygen-derived species. The generation of chemilumine-scence (CL) by peritoneal macrophages from 12 dayT. musculi-infected mice, which phagocytose and kill parasites when opsonizing antibodies are present, was recorded in the presence of antibody-coated trypanosomes. Taurine, a specific quencher of hypochlorous acid (HOCl) inhibited CL production by peritoneal macrophages, showing that HOCl is produced during phagocytosis ofT. musculi.In vitro, HOCl alone exerted a powerful trypanocidal activity which was inhibited in the presence of specific quenchers. The role of HOCl generated by phagocytes in trypanosome killing was studied using granulocytes which produce more oxygen-derived species than macrophages when stimulated. Phorbol myristate acetate-triggered granulocytes can destroyT. musculiand trypanosome killing is inhibited in the presence of taurine. These data demonstrate that HOC1 produced by phagocytes can effectively destroyT. musculi.
Host predisposition to trichuriasis: the mouse — T. muris model
Authors: Else K. J. , Wakelin D. , Roach T. I. A. 
Published: June 2009

SUMMARYPredisposition to trichuriasis in mice is reflected in the inability of certain strains, or certain individuals within strains, to express protective immunity. Poor responders fail to expel worms and harbour chronic patent infections. The mechanisms underlying this phenomenon were studied in poor responder mice challenged after abbreviated or prolonged primary infections. Mice exposed to a complete primary infection were fully susceptible when challenged after the removal of the primary infection by anthelmintic. Failure to expel either infection suggests (a) that non-responsiveness to a primary infection does not reflect an inability to expel worms of a certain size, i.e. is not a consequence of the speed of the immune response in relation to parasite growth and (b) that non-responsiveness is long-lasting. Challenge after abbreviation of primary infections at different stages of worm development showed that persistence of larvae beyond day 21 was critical in determining poor response to reinfection. By inference the same conclusion can be drawn about the inability of such mice to expel primary infections. Serological analysis suggested a relationship between low antibody titres, restricted antigen recognition profiles and resistance to infection. It is suggested that the later stages of parasite development are immunosuppressive; the implications for human trichuriasis are discussed.
Mechanisms of immunity to malaria and the possibilities of a blood-stage vaccine: a critical appraisal
Authors: Butcher G. A. 
Published: June 2009

SUMMARYResistance developed by the immune system in response to blood-stage malaria is complex in nature, involving humoral and non-antibody effector mechnisms. Different species of malarial parasites may vary in their ability to elicit, or their susceptibility to, those immune effectors. This complexity is enhanced by the different results obtained in vaccinated as opposed to drug-controlled infections. It is therefore important that some attempt be made to unravel these interactions. This is particularly so when we have to decide on methods for assessing the potentiality of antigens to induce protective immunity. In this review the limitations of somein vitroassays of immunity, as well as those of various host–parasite models, are discussed. The relative importance of cell-mediated and humoral immunity in laboratory models and natural infections is also considered in the context of vaccine development.
Strongyloides ratti: relative importance of maternal sources of infection
Authors: Zamirdin Mohamed , Wilson Peter A. G. 
Published: June 2009

Milk-borne infection is demonstrated for Strongyloides ratti in rats, accounting for 32% of the combined worm burden of non-immune mothers plus their offspring at a standard dose of 4000 L3. Migrating larvae are ‘switched’ to the mammary gland about 3 days prepartum in advance of the final events of lactogenesis in the host at 30 h prepartum. Larvae take between 24–48 h to reach the milk after injection.The ‘take’ in lactating rats was half that in virgin controls and pregnant animals before day 3 prepartum, but this discrepancy was not made up by the number of worms in the litter, the combined figure for mothers and offspring still being only 75% of the potential judged by the controls.Prenatal infection did not occur in these experiments, which involved carefully controlled cross-fostering between infected and uninfected mothers. Injections of larvae covered the period between 12 days to 20 h prepartum in different animals. This route is possible under other circumstances, although it is considered unlikely in non-immune females since there was no evidence of larval dormancy in maternal tissue.