bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trichinella spiralis: antigenic epitopes from the stichocytes detected in the hypertrophic nuclei and cytoplasm of the parasitized muscle fibre (nurse cell) of the host
Authors: Lee D. L. , Ko R. C. , Yi X. Y. , Yeung M. H. F. 
Published: June 2009

SUMMARYMonoclonal antibodies raised against antigens present in the excretions/secretions (E/S) of larvalTrichinella spiralis, polyclonal antibodies raised against E/S and antisera from rabbits and pigs infected withT. spiraliswere used in conjunction with immunocytochemical techniques to detect antigens in sections of muscle from mice that had been infected withT. spiralisfor 15 or 30 days. The antibodies recognized epitopes in the stichocytes, on the surface of the cuticle, in the lumen of the oesophagus and in the lumen of the intestine of encysted larvae. Monoclonal antibodies 7C2C5and 1H7 and the polyclonal antibodies recognized epitopes in the cavity occupied by the larva, in the cytoplasm of the nurse cell, and in the hypertrophic nuclei of the nurse cell, but did not recognize material in the smaller nuclei of the nurse cell, in the cyst wall or in the surrounding muscle. Monoclonals 3B2E6 and 1D11G8B2, which recognized epitopes in the stichocytes and on the surface of the cuticle of the larvae, gave negative results with the cytoplasm and nuclei of the nurse cell. A polyclonal antibody raised againstTrichuris suisrecognized epitopes in the muscle and hypodermis of encystedT. spiralisbut gave negative results with material in the nurse cell and nurse cell nuclei. The possibility that the antigen detected in the cytoplasm and nuclei of the nurse cell is produced by the stichocytes of the nematode and that it is controlling genes of the altered muscle fibre, either directly or indirectly, is discussed.
Frequency distribution of lymphatic filariasis microfilariae in human populations: population processes and statistical estimation
Authors: Grenfell B. T. , Das P. K. , Rajagopalan P. K. , Bundy D. A. P. 
Published: June 2009

SUMMARYThis paper uses simple mathematical models and statistical estimation techniques to analyse the frequency distribution of microfilariae (mf) in blood samples from human populations which are endemic for lymphatic filariasis. The theoretical analysis examines the relationship between microfilarial burdens and the prevalence of adult (macrofilarial) worms in the human host population. The main finding is that a large proportion of observed mf-negatives may be ‘true’ zeros, arising from the absence of macrofilarial infections or unmated adult worms, rather than being attributable to the blood sampling process. The corresponding mf distribution should then follow a Poisson mixture, arising from the sampling of mf positives, with an additional proportion of ‘true’ mf-zeros. This hypothesis is supported by analysis of observed Wuchereria bancrofti mf distributions from Southern India, Japan and Fiji, in which zero-truncated Poisson mixtures fit mf-positive counts more effectively than distributions including the observed zeros. The fits of two Poisson mixtures, the negative binomial and the Sichel distribution, are compared. The Sichel provides a slightly better empirical description of the mf density distribution; reasons for this improvement, and a discussion of the relative merits of the two distributions, are presented. The impact on observed mf distributions of increasing blood sampling volume and extraction efficiency are illustrated via a simple model, and directions for future work are identified.
Frequency distribution of Wuchereria bancrofti microfilariae in human populations and its relationships with age and sex
Authors: Das P. K. , Manoharan A. , Srividya A. , Grenfell B. T. , Bundy D. A. P. , Vanamail P. 
Published: June 2009

SUMMARYThis paper examines the effects of host age and sex on the frequency distribution of Wuchereria bancrofti infections in the human host. Microfilarial counts from a large data base on the epidemiology of bancroftian filariasis in Pondicherry, South India are analysed. Frequency distributions of microfilarial counts divided by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. Parameter estimates from the fits indicate a significant trend of decreasing overdispersion with age in the distributions above age 10; this pattern provides indirect evidence for the operation of density-dependent constraints on microfilarial intensity. The analysis also provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors (around 5% of the total negatives). This allows the construction of corrected mf age–prevalence curves, which indicate that the observed prevalence may underestimate the true figures by between 25% and 100%. The age distribution of mf-negative individuals in the population is discussed in terms of current hypotheses about the interaction between disease and infection.
Estimation of relative fecundity inEimeria tenellastrains by a mixed infection method
Authors: Nakamura T. , Konishi T. , Kawaguchi H. , Imose J. 
Published: June 2009

SUMMARYThe relative fecundity of populations ofEimeria tenellawas estimated by means of mixed infection using electrophoretic variation of glucose-phosphate isomerases (GPIs) as a genetic marker. A decoquinate-resistant strain with GPI-9 isozyme (DR-NIAH), a decoquinate-sensitive one with GPI-1 (DS-Iwate), and three decoquinate-resistant lines (No. 3, 4, and 5) derived from cross-fertilization between DR-NIAH and DS-Iwate, were used. The GPI phenotypes of the No. 3 and No. 4 lines are GPI-9, and that of No. 5 is GPI-1. Mixed infection experiments were performed between DR-NIAH and DS-Iwate, No. 3 and No. 5, and No. 4 and No. 5. DR-NIAH was predominant over DS-Iwate in the mixed infection, whereas, in single infections, the total oocyst output of DR-NIAH was similar to or less than that of DS-Iwate. Among three lines, No. 4 was predominant over No. 5, and No. 5 was predominant over No. 3 in the mixed infection. Relative fecundity between No. 3 and No. 5 and their patterns of oocyst output in single infections were similar to those in the mixed infection. In contrast, No. 5 produced more oocysts than No. 4 in single infections, suggesting that the oocyst production in the mixed infection may be influenced by the mutual interference or competition between the populations ofE. tenellain the chicken caeca.
Studies on a murine model of congenital toxoplasmosis: vertical disease transmission only occurs in BALB/c mice infected for the first time during pregnancy
Authors: Roberts C. W. , Alexander J. 
Published: June 2009

SUMMARYThe incidence of congenital toxoplasmosis was determined by an ELISA in the litters of BALB/c mice which had been infected 8 weeks before mating, on day 12 of pregnancy, or on both these occasions. Of those mice given the infection for the first time on day 12 of pregnancy, 5 out of 6 gave birth to infected litters with approximately 50% of the individuals in each litter being infected. BALB/c mice which had been infected 8 weeks before mating did not give birth to infected litters, even if they were reinfected on day 12 of pregnancy. Following infection BALB/c mice were found to harbour significantly fewer tissue cysts than the congenic H-2 derivative BALB/K strain. However, chronically infected BALB/K mice also failed to produce infected litters, indicating that tissue cyst burden in the dam did not influence congenital infection at least on the BALB background. This study demonstrates that BALB/c dams chronically infected withToxoplasma gondii, have immunity capable of protecting their embryos from congenital infection, even if the dams are reinfected during pregnancy. Our results demonstrate that the BALB/c mouse can be used as a model of human or ovine congenitalT. gondiiinfection suitable for testing putative vaccines.
Praziquantel: physiological evidence for its site(s) of action in magnesium-paralysedSchistosoma mansoni
Authors: Blair K. L. , Bennett J. L. , Pax R. A. 
Published: June 2009

SUMMARYThe mechanism whereby praziquantel produces a contraction and subsequent flaccid paralysis (a loss of sensitivity to subsequent stimuli) ofSchistosoma mansoniin a medium containing an elevated Mg2+:Ca2+ratio was investigated. In RPMI, praziquantel produced a concentration-dependent tonic contraction of the parasite with an EC50of 200 nM. Magnesium inhibited the contraction in such a manner as to convert the tonic contraction to a phasic one without altering the peak force generated. The Mg2+-dependent block was non-competitive with praziquantel but was competitive with extracellular Ca2+, ratios of 7·5:1; Mg2+: Ca2+being needed to inhibit the tonic contraction and to induce flaccid paralysis. Flaccid paralysis was associated with a reduced ability of the parasite to take up45Ca2+from the bath compared to parasites that had not entered into flaccid paralysis and flaccid paralysis was reversible. Recovery from flaccid paralysis was accelerated by treatments that are expected to increase Ca2+uptake by the parasite. At a concentration of 500 nM, praziquantel produced 2 distinct phasic contractions in intact parasites incubated in an elevated [Mg2+] medium but only 1 phasic contraction in parasites lacking their surface tegumental membranes. In zero Ca2+I-RPMI, 10 μM praziquantel produced a phasic contraction of intact parasites but did not stimulate contraction of detegumented parasites until Ca2+was reintroduced into the bath. These results indicate that praziquantel interacts with specific Ca2+-permeable sites in the tegumental and sarcoplasmic membranes of the parasite and that under these conditions of elevated Mg2+:Ca2+ratios, these sites become blocked by Mg2+, leading to flaccid paralysis of the parasite.
Experimental population dynamics of Rhabdias bufonis (Nematoda) in toads (Bufo bufo): density-dependence in the primary infection
Authors: Goater C. P. 
Published: June 2009

SUMMARYDensity-dependence in worm establishment, numbers, biomass and larval production were examined in primary infections of 0, 10, 40, 80 and 160 larvae of the lung nematode, Rhabdias bufonis in the common toad, Bufo bufo. The infection procedure established 4 non-overlapping levels of infection which persisted until 6 weeks post-infection (p.i.), after which there was an overall decline up to 12 weeks p.i. Worm numbers had no direct effect on adult worm survival but temporal changes in worm weight were density-dependent. Adult worm establishment in the lungs declined significantly as the numbers of worms in the lungs increased. At the lowest exposure dose, 86% of the larvae administered reached maturity in the lungs while at the highest, only 37% did so. Also, the numbers of immature larvae outside the lungs increased as adult worm numbers increased. Both features provide evidence for a threshold limit to the numbers of worms maturing in the lungs. Worm numbers also affected larval output per host and per capita fecundity. A significant positive relationship between per capita fecundity and per capita worm weight suggested that density-dependence acted primarily to constrain the growth of individual worms. Finally, the constraints imposed on worm growth and fecundity were apparently relaxed when worm density decreased, providing evidence for density-dependent flexibility in per capita fecundity. Density-dependence in worm establishment and per capita fecundity are mechanisms which may potentially regulate this host–parasite interaction in the field. Both mechanisms may be functionally related to physical space limitations in the lungs, within which worms must compete for finite nutrients.
High frequency of antigenic variation inTrypanosoma brucei rhodesienseinfections
Authors: Turner C. M. R. , Barry J. D. 
Published: June 2009

SUMMARYRates at whichTrypanosoma bruceirhodesiense trypanosomes switch from expression of one variable antigen type (VAT) to that of another have been determined in cloned populations that have been recently tsetse-fly transmitted. Switching rates have been determined between several, specific pairs of VATs in each population. High rates of switching were observed in 2 cloned trypanosome lines, each derived from a separate cyclical transmission of the same parental stock and each expressing a different major VAT. Five estimates of the switching rate between one particular pair of VATs were consistently high (approximately 1 × 103switches/cell/generation). These high switching rates were similar both in bloodstream populations of mice and in populations confined to subcutaneously implanted growth chambers in mice, thus indicating that the interaction of the bloodstream population with other trypanosome populations in the lymphatics or extravascular sites in systemic infections did not influence the estimates of the rate of switching. Fourteen estimates were made of VAT-specific switching rates in bloodstream infections involving 8 combinations from among 6 VATs. Switching rate estimates were VAT-specific and showed considerable variation between different combinations of VATs — from 1.9 × 10−6to 6.9 × 10−3switches/cel/generation. The rates of switching to different metacyclic-VATs were, however, very similar. Summation of between 3 and 5 VAT-specific switching rate values in each of 4 experiments conducted in bloodstream infections has provided minimum estimates of the overall rate of antigenic variation: 2.0−9.3 × 10−3switches/cell/generation. These values are between 20 and 66000-fold higher than previously published estimates. It is likely that at least 1 in every 100 trypanosomes switches its VAT expression every generation.
Theilerial parasites isolated from carrier cattle after immunization withTheileria parvaby the infection and treatment method
Authors: Maritim A. C. , Young A. S. , Lesan A. C. , Ndungu S. G. , Mutugi J. J. , Stagg D. A. 
Published: June 2009

SUMMARYGroups of cattle were immunized with 10−2dilutions of sporozoite stabilates ofTheileria parva lawrenceiderived from African buffaloes either alone or in combination withTheileria parva parvaderived from cattle and concomitant treatment with either long or short-acting formulations of oxytetracyline. At 90 or 120 days after infection, uninfectedRhipicephalus appendiculatusnymphal ticks were applied to individual immunized cattle and the resultant adults ticks were applied to individual susceptible cattle. Theilerial infection developed from ticks fed on 6 out of 11 animals investigated for evidence of a carrier state. Two additional animals were shown by cell-culture isolation to have persistent theilerial infections. Nine cattle infected with the parasites from carrier animals were treated with parvaquone and 7 recovered. These recovered cattle were then challenged with the original immunizing stabilates at 10° dilution together with the original immunized and carrier cattle. Six out of 7 cattle which had recovered from carrier-derived infection succumbed to this challenge and died but none of the original immunized cattle showed theilerial reactions. When a carrier-derived sporozoite stabilate was used to challenge cattle immune to the original immunizing parasite, they proved to be immune. Cattle immune to the carrier-derived parasites were all immune to challenge with the original parasite. A monoclonal antibody profile aginstT. parvaschizonts isolated by cell culture from samples of the experimental animals did not appear to be sensitive enough to determine the antigenic differences between the carrier-derived parasite and the original immunizing parasite. Indications are that the carrier state is not likely to produce new antigenic strains which would be dangerous to immunized cattle.
Identification of common surface antigens amongBabesia bigeminaisolates by using monoclonal antibodies
Authors: Figueroa J. V. , Buening G. M. , Kinden D. A. , Green T. J. 
Published: June 2009

SUMMARYA group of monoclonal antibodies (MAb) was used to immunochemically characterizeBabesia bigeminasurface components. Two surface reactive MAb by an IFAT test were subsequently shown to bind to epitopes on the external surface of the parasite plasma membrane as evidenced by immunoelectron microscopy. Parasite components with relative sizes of 68, 62, 60, 58, 56, 54, 51, 49, 48, 47, 43, 36 kDa were identified with the group of MAb in at least 6 geographically differentB. bigeminaisolates. The antigenic components were demonstrated to be species-specific and apparently predominant. Both polyclonal antibodies (immune bovine serum) and highly diluted MAb specifically reacted with such bands producing a strong signal in Western blots.
The effect ofPlasmodium falciparumexo-antigens on the morphology of uninfected erythrocytes
Authors: Read D. G. , Bushell G. R. , Kidson C. 
Published: June 2009

SUMMARYIt was observed that uninfected red cells resuspended in supernatant fromPlasmodium falciparumcultures, then examined between a glass slide and cover-slip, assumed varying morphologies. A series of experiments suggested thatP. falciparumreleases molecules which cause red cells to become stomatocytic (cupped). These molecules, some of which are heat- stable, have an apparent molecular weight < 12 kDa, are released at or about schizogony, and do not bind tightly to erythrocytes.
The serotoninergic, cholinergic and peptidergic components of the nervous system in the monogenean parasite,Diclidophora merlangi: a cytochemical study
Authors: Maule A. G. , Halton D. W. , Johnston C. F. , Shaw C. , Fairweather I. 
Published: June 2009

SUMMARYConfocal scanning laser microscopy has been employed with immunocytochemical techniques to map the distribution of serotoninergic and peptidergic components in the nervous system of the monogenean gill-parasite,Diclidophora merlangi; results are compared with the distribution of cholinergic components, following histochemical staining for cholinesterase activity. While all three neurochemical elements are present in the central and peripheral nervous systems, the cholinergic and peptidergic systems dominate the CNS, whereas the PNS has a majority of serotoninergic nerve fibres. The cholinergic and peptidergic neuronal pathways overlap extensively in staining patterns, suggesting possible co-localization of acetylcholine and neuropeptides. Within the peptidergic nervous system, immunoreactivity to the pancreatic polypeptide family of peptides and FMRFamide were the most prevalent.
Regulation of macrophage-mediated larvicidal activity inEchinococcus granulosusandMesocestoides corti(Cestoda) infection in mice
Authors: Jenkins P. , Dixon J. B. , Rakha N. K. , Carter S. D. 
Published: June 2009

SUMMARYKilling of metacestodes by normal or post-infection macrophages and the regulation of this activity by cytokines were studied invitro. The protoscolecidal activity of normal macrophages againstEchinococcus granulosuswas inhibited by a product of naive T-enriched lymphocytes co-cultured with protoscoleces (PSC). By contrast, supernates from co-cultures ofMesocestoides cortitetrathyridia (MCT) and T-enriched or B-enriched normal lymphocytes increased killing of MCT by normal macrophages. Larvicidal activity (against both PSC and MCT) was enhanced by high concentrations of macrophage-activating factors produced by Con A-stimulated rat lymphocytes (Con A-LK), but was reduced by low concentrations of these factors.
The sex ratio of Plasmodium gametocytes
Authors: Schall J. J. 
Published: June 2009

SUMMARYSex ratio theory usually predicts an equilibrium sex ratio and equal proportions of males and females in a population, including the progenitors of the reproductive cells of protozoans. This proposal was tested with three species of malarial parasites of lizards, Plasmodium mexicanum of the western fence lizard, and P. agamae and P. giganteum of the African rainbow lizard, using single samples from naturally infected lizards, repeated samples from free-ranging lizards (P. mexicanum only), and repeated samples from laboratory maintained animals. Macrogametocytes were usually more abundant than microgametocytes, and were slightly larger, revealing a typically greater investment of resources by the progenitors of female reproductive cells. However, the proportion of microgametocytes varied among the three species and among infections within each species of Plasmodium. The sex ratio of gametocytes often remained constant within infections followed over time even if the absolute number of gametocytes was changing. However, the equilibrium sex ratio of gametocytes varied among those infections that had an unchanging microgametocyte proportion. Thus, although an equilibrium sex ratio apparently occurs for most infections, there appears to be no characteristic proportion of microgametocytes for any of the species. Potential explanations for this conflict with theory are presented.
Transport processes of 2-deoxy-D-glucose in erythrocytes infected withPlasmodium yoelii, a rodent malaria parasite
Authors: Izumo A. , Tanabe K. , Kato M. , Doi S. , Maekawa K. , Takada S. 
Published: June 2009

SUMMARYThe transport processes of D-glucose inPlasmodium yoelii-infected mouse erythrocytes were investigated using 2-deoxy-D-glucose (2DOG), a non-metabolizable analogue of D-glucose. Infected cells showed an increase in the uptake of 2DOG compared to uninfected controls, and an effect which was more prominent in cells with mature-stage parasites. Kinetic studies measuring the initial rates of 2DOG uptake revealed two components in infected cells with late trophozoite and schizont-stage parasites: a simple diffusion system and a carrier (transporter)-mediated system. The transporter was common for D-glucose and 2DOG and had a kinetic constant indicating a high affinity for 2DOG (theKm= 0·18 mM and theVmax= 0·61 mmol/1010cells/min), as compared to the constant of the mouse erythrocyte carrier (theKm= 10 mM and theVmax= 1·8 mmol/1010cells/min). Determination of the distribution of [3H]2DOG in infected cells and experiments with metabolic inhibitors indicated that the simple diffusion system localizes in the membrane of host cells and the transporter in the parasite plasma membrane. The parasite glucose transporter was much less sensitive to cytochalasin B than that of the host cells and the uptake of 2DOG via the transporter was dependent on energy. Based on these findings, the following features emerge: D-glucose first gains access to the cytosol of infected erythrocytes via the simple diffusion system, which appears after infection by the parasite, and an active uptake against the concentration gradient takes place at the parasite plasma membrane via the parasite glucose transporter in an energy dependent manner. Finally, an energy transduction mechanism for the transport of glucose across the parasite plasma membrane is discussed.