bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic control of resistance to infection with Nematospiroides dubius in mice: selection of high and low immune responder populations of mice
Authors: Sitepu P. , Dobson C. 
Published: June 2009

SUMMARYF1, Quackenbush (Q) × Wild (W) Mus musculus were assayed and selected for their level of immunity to secondary infections with 100 Nematospiroides dubius using faecal parasite egg counts. A significant positive linear correlation was found between the number of parasite eggs voided in the faeces and the number of N. dubius recovered after secondary infections in mice. Selection for immunity was not influenced by the conformation of the mice. High (H) and low (L) responder colonies together with a randomly (Rd) bred colony of mice were established over 5 generations. Adaptive immunity was more efficacious in protecting female than male mice and appeared to be controlled by a few dominant genes; the heritability (h2) of the trait was estimated at 0·56 for the parental stock and 0·55 for the F5 Rd colony and the realized heritability was 0·49. Higher anti-N. dubius antibody titres were detected in H than L mice. H mice harboured fewer and less fecund parasites than Rd colony mice; L mice had more worms with greater fecundities than Rd mice. The levels of primary infection in H and L mice related to the levels developed after secondary infection from F4. This suggested at least partial linkage of genes controlling innate with genes controlling adaptive immunity against N. dubius.
Population dynamics ofAngiostrongylus cantonensisduring primary infections in rats
Authors: Kwong Yong Weng , Dobson Colin 
Published: June 2009

SUMMARYAbout 35 ofAngiostrongylus cantonensislarvae became patent adults irrespective of the dose used to establish primary infections in laboratory rats. Worm growth and fecundity was depressed in infections from high compared with low doses of infective larvae. Rats infected with up to 50A. cantonensislarvae survived infection better than rats given greater numbers of larvae. The biology ofA. cantonensissurviving in laboratory rats from single infections with 50 larvae for over a year was studied. Stable worm numbers and fecundity were established 90 days after infection but the worms continued to grow until the experiment was terminated.
Schistosoma mansoni: host antigen occurrence on worms recovered from laboratory vertebrate animals
Authors: Coelho P. M. Z. , Gazzinelli G. , Pellegrino J. 
Published: June 2009

SUMMARYBy transferringSchistosoma mansoni(12 to 14-day-old worms) from one host into the peritoneal cavity of a host of a different species, it was possible to demonstrate that worms grown in rats, hamsters,Mastomys natalensisandCebusmonkeys were rejected by recipient animals previously immunized against red blood cells of the donor hosts. These results suggest that host-like antigens are acquired byS. mansoniin all hosts. The transfer of worms into the peritoneal cavity has proved to be a simple and convenient method for studying the presence of host antigens inS. mansoni.
Uptake of purine bases and nucleosides in African trypanosomes
Authors: James Dinah M. , Born G. V. R. 
Published: June 2009

SUMMARYUptake of radioactively labelled purine bases and nucleosides by suspensions ofTrypanosoma bruceiandTrypanosoma congolensein bicine buffer was determined at 37 °C. WithT. brucei, the rate of uptake of adenosine was much greater than that of the other compounds tested, the uptake of which decreased in the order adenine, inosine, guanosine and hypoxanthine. WithT. brucei, adenosine uptake increased with concentration in a manner suggesting two mechanisms, one with high and the other with low affinity for adenosine. The uptake of adenine increased with concentration only up to about 1·5 µM while the uptake of guanosine increased little with concentration and that of inosine and hypoxanthine not at all. In both species adenosine strongly inhibited the uptake of both of the other nucleosides and of both purine bases. InT. brucei, guanosine and inosine caused small increases in adenosine uptake which was, however, inhibited by them inT. congolense. InT. brucei, each of the purine bases adenine and hypoxanthine inhibited its own uptake maximally but that of each other less effectively. Hypoxanthine was more effective than adenine in inhibiting the uptake of the nucleosides guanosine and inosine, but neither base effected marked inhibition of adenosine uptake. The uptake of adenosine byT. bruceiwas inhibited by dipyridamole and its analogue, compound RA–233, strongly at 100µM and slightly at 10 µM. The other dipyridamole analogues, VK–744 and VK–774, were ineffective.
Biochemical surface components ofBrugia pahangimicrofilariae
Authors: Sayers G. , Mackenzie C. D. , Denham D. A. 
Published: June 2009

SUMMARYThe sheath and cuticle of microfilariae ofBrugia pahangiwere examined by electron microscopy and the presence of various proteins, carbohydrate and enzymes sought. The epicuticle of microfilariae consists of a pentalaminate structure (24·0 ± 1·4 nm), a cortex (13·7 ± 3·6 nm) and a basal zone (27·8 ±4·8 nm) which is often banded in appearance. The pentalaminate layers are not continuous at the base of the interannular grooves. The sheath and the epicuticle ofB. pahangistained positively with concanavalin A and saccharated iron oxide. The sheath of approximately 50% of microfilariae showed activity for acid phosphatase, 5′ nucleotidase and peroxidase, but not for ATPases, alkaline phosphatase or esterase. No enzymes were detected in the epicuticle although the cortex and basal layers of the cuticle did show enzymic activity. Structures beneath the cuticle in the main body of the worms contained considerable enzymic activity. Microfilariae directly isolated from the blood of infected cats were found by immunochemical means to carry serum proteins on their sheaths but not on their cuticles. These studies extend the definition of the outer structures of microfilariae and confirm that they significantly differ in morphology and enzyme content from typical mammalian cell membranes.
Morphological and adhesive changes to cultured chick kidney cells following parasitization withEimeria tenella(Protozoa: Coccidia)
Authors: Urquhart Catriona 
Published: June 2009

SUMMARYCultured adult chick kidney (CK) cells inoculated with sporozoites ofEimeria tenellashowed progressive alterations in their morphological and adhesive characteristics. Scanning electron microscopy (SEM) showed that during a 3-day period following the inoculation of parasites there was a gradual loss of contact between the cells. Initially, the cells remained connected by long cytoplasmic bridges but with the breakdown of these, the cells began to round up, losing complete contact with each other and remaining attached to the substratum by means of retraction fibres. By 3 days many cells had completely detached. The factors inducing these alterations were transmissable via the medium as the alterations were mimicked by non-parasitized cells in co-culture with parasitized cells. Studies with the reflection interference microscope (RIM) showed that the changes were accompanied by an increase in the cell-substrate separation distance and the loss of focal contacts. These changes were not effected by substances transmissable via the medium. Parasitized cells showed enhanced agglutination with Concanavalin A (Con A) which could be eliminated by pre-fixation. The possibility that changes to the host cell indicate a rearrangement of cytoskeletal apparatus is discussed.
Comparison between spring and autumn infection by Corynosoma (Acanthocephala) in the ringed seal Pusa hispida in the Bothnian Bay of the Baltic Sea
Authors: Helle Eero , Valtonen E. Tellervo 
Published: June 2009

SUMMARYCorynosoma spp. (Acanthocephala) infection in ringed seals (Pusa hispida) is compared in spring and in autumn in the Bothnian Bay, northern Baltic Sea. The material consists of more than 13400 specimens: 7590 from the intestines of 13 seals captured in April and May 1978 and 5850 from 29 seals captured in October and November.Corynosoma strumosum infection had approximately the same intensity in spring and autumn (mean 76 and 66 individuals/infected seal, maxmum 313 and 324 individuals, respectively). C. semerme specimens, on the other hand, were 37 times more numerous in spring than in autumn (504 compared with 136/infected seal, maximum 1700 and 1230 individuals, respectively). The ratio of C. strumosum to C. semerme was 1:6·3 in spring and 1:2·0 in autumn, as calculated from the total material. Corynosoma infection was more recent on average in spring than in autumn, as judged both from the proportion of males and immature females and from the distribution of C. semerme in the intestine. The feeding habits of the ringed seals and the rate of development of Corynosoma infection are discussed.
Fasciola hepatica: development of the tegument of normal and γ-irradiated flukes during infection in rats and mice
Authors: Burden D. J. , Bland A. P. , Hughes D. L. , Hammet N. C. 
Published: June 2009

SUMMARYRats and mice were infected with either normal metacercariae or metacercariae γ-irradiated at 3 krad. or 4 krad. Flukes were recovered at various times after infection and their teguments examined using a transmission electron microscope. In normal flukes, the secretory granules TO, Tl and T2 were all seen during tegumental development. The teguments of flukes from mice developed faster than the corresponding teguments in rats. TO granules were present from day 0 to day 10 post-infection (p.i.) in mouse flukes and from day 0 to day 14 p.i. in rat flukes. Tl granules first appeared in mouse flukes by day 4 p.i. but not until day 8 p.i. in rat flukes. T2 granules were seen in mouse flukes 2 days p.i. but not before 6 days p.i. in rat flukes. γ-Irradiation at 4 krad prevented normal tegumental development in flukes from both rats and mice. TO granules were present at all times in flukes from either host. Tl granules were produced in mouse flukes but their appearance was delayed until day 6 p.i. No significant production of T2 granules occurred in flukes from either host. Parasite survival was also affected by γ-irradiation and none of the flukes reached maturity. Flukes from rats died between 10 and 21 days p.i and flukes from mice died between 14 and 28 days p.i. γ-Irradiation of metacercariae at 3 krad. had an extremely variable effect on subsequent tegumental development in both rats and mice. Some flukes developed normally, some showed development associated with γ-irradiation at 4 krad, whilst some showed intermediate development.
Experimental amoebiasis and the development of anti-amoebic compounds
Authors: Neal R. A. 
Published: June 2009

In the ideal situation, the development of new amoebicides, or more accurately anti-amoebic compounds which are compounds with activity againstEntamoeba histolytica, should initially proceed with the study of parasite-specific metabolic pathways and their inhibition, followed by whole parasitein vitrostudies, experimentalin vivomodels and finally clinical trial. However, there are considerable gaps in our knowledge which will be discussed below, and consequently many investigators consider that empirically selected compounds should be tested experimentally in addition to specifically designed compounds. Before clinical trials can begin, extensive examination of the candidate amoebicide in experimental animals is required in order to investigate possible toxicological hazards.In addition to inhibiting the amoebic parasite, the drug has to reach the parasite in several different sites in the body, thus there is also a problem of pharmacokinetics and distribution. Prior to the discovery of the nitroimidazole class of amoebicides, the multi-site attack was solved by the use of several drugs, sometimes in sequence during the treatment of an individual case (Powell, 1972). The discovery of the nitroimidazole class of compound changed the situation dramatically and these have shown a clinical and parasitological effect against extra-intestinal and intestinal wall infections. The effect on intralumenal infection (that is mildly symptomatic or asymptomatic infections) of the large intestine is, however, less certain (Finegold, 1977; Spillman, Ayala & Sanchez, 1976).Although the treatment of amoebiasis appears to be satisfactory at the present time, it is difficult to predict problems which might arise in the future, and therefore it is valuable to continue the pre-clinical development, especially the investigation of parasite metabolism, in order to define parasite-specific points of chemotherapeutic attack.The chemotherapy of amoebiasis was reviewed comprehensively by Woolf (1963, 1965). The present account of the development of amoebicides therefore starts from the Woolfe reviews.
Echinococcus granulosus: specificity of amino acid transport systems in protoscoleces
Authors: Jeffs S. A. , Arme C. 
Published: June 2009

SUMMARYProtoscoleces ofEchinococcus granulosusabsorb the l-amino acids proline, methionine, leucine, alanine, serine, phenylalanine, lysine and glutamic acid by a combination of mediated transport and diffusion. All eight amino acids were accumulated against a concentration gradient. Comparison ofKtandVmaxvalues suggests that a low affinity for a particular compound is compensated for by a relatively larger number of transport sites for that compound. Four systems serve for the transport of the eight substrates studied: 2 for neutral (EgNl, EgN2) and 1 each for acidic (EgA) and basic (EgB) amino acids. All eight amino acids are incorporated into protein to varying degrees and substantial portions of absorbed l-alanine and l-methionine are metabolized into other compounds.
The epidemiology ofOstertagia ostertagiand other gastrointestinal nematodes of cattle in Louisiana
Authors: Williams J. C. , Knox J. W. , Marbury K. S. , Kimball M. D. , Baumann B. A. , Snider T. G. 
Published: June 2009

SUMMARYThe epidemiology ofOstertagia ostertagiand other gastrointestinal nematodes in yearling beef cattle was examined in each of 2 successive years. During each year 50 head of newly weaned beef calves were given a single dose of thiabendazole and then placed on experimental pastures. Twenty-four of the animals were designated for monthly slaughter (n= 2) and analysis of worm population characteristics and 25 were designated for blood and faecal collection and for weighing. Parasite-free tracer calves were grazed alongside the yearling cattle each month (n= 2) throughout the 2 years and were also slaughtered for analysis of worm populations. Faecal egg counts, plasma pepsinogen determinations, herbage larval counts, and animal liveweight changes were recorded monthly. Results of this work substantiated previous observations on seasonal changes of populations of the different nematode genera, but greater continuity and definition of patterns was possible in the present work.Ostertagia ostertagiwas the predominant nematode present. While minimal numbers of inhibited larvae were observed from autumn into winter, most of the population was adult at this time. Acquisition of inhibition-prone larvae begins in late winter and peak numbers are acquired between March and June. Little transmission ofO. ostertagioccurs between June and September.Trichostrongylus axeihad a similar seasonal prevalence toO. ostertagi.A major difference in the 2 years was in the pattern of maturation of inhibited larvae. This occurred early, during May 1981, following below average temperatures in May and above average rainfall in May and June. Overt type II disease was not associated with a smaller level of maturation in autumn 1981. In contrast, maturation of large burdens of inhibited larvae did not occur until autumn 1982 following a protracted period of dry and hot weather from spring. Acute type II disease was observed in autumn 1982. Reasons for the differences in maturation pattern, based on worm counts from yearling cattle and tracer calves and association of these with faecal egg counts, herbage larval counts, clinical condition, and liveweight changes are discussed.
The relationship between the density of Fasciola hepatica miracidia and the net rate of miracidial infections in Lymnaea truncatula
Authors: Smith G. 
Published: June 2009

SUMMARYExperimental studies on the dynamics of infection of Lymnaea truncatula by the miracidia of Fasciola hepatica show that there is a linear relationship between the net rate of attachment of miracidia to snail epithelium and the density of infective stages. The probability of a snail remaining uninfected after exposure to a single miracidium varies with the size class of the snail. Under the conditions of the experiment (temperature, 15° C; exposure period, 30 min; water volume, 8 ml), the probability was 0·46–0·48, 0·27–0·26 and 0·13–0·19 for snail size classes, 0·5–2·9, 3·0-5·9 and 6·0-8·9 mm respectively.
Detection of circulating trypanosomal antigens by double antibody ELISA using antibodies to procyclic trypanosomes
Authors: Liu M. K. , Pearson T. W. 
Published: June 2009

SUMMARYA double antibody sandwich ELISA technique has been developed for detection of antigens of African trypanosomes present in the sera of infected mammals. The assay uses a high titre, high affinity rabbit antiserum made to purified membranes of procyclic trypanosomes as ‘capture’ reagent and a mixture of three biotin-labelled trypanosome-specific monoclonal antibodies as detecting reagent. The monoclonal antibodies were chosen on the basis of their specificity for surface membrane antigens ofTrypanosoma bruceispp., the relative abundance and solubility of their specific antigen in aqueous solvents (including serum), and the fact that each monoclonal antibody binds to distinct epitopes on the same antigen molecule. Thus, antigen capture from serum and subsequent detection was achieved using as little as 10 ng/ml of whole trypanosome lysate, or the equivalent of 5000 trypanosomes/ml when solubilized material was added to normal serum in an artificial system. Using the optimized assay, antigen was detected in the sera of trypanosome-infected mice as early as 2 days after infection withT. b. rhodesiense.The results indicate that the assay allows detection of low concentrations of specific membrane antigens ofT. bruceispp. of African trypanosomes and thus may have immunodiagnostic utility.
Evidence for predisposition in humans to infection with Ascaris, hookworm, Enterobius and Trichuris in a South Indian fishing community
Authors: Haswell-Elkins M. R. , Elkins D. B. , Anderson R. M. 
Published: June 2009

SUMMARYStudies of patterns of reinfection with four species of intestinal nematodes (Ascaris, hookworm, Trichuris and Enterobius) in 174 individual patients following chemotherapeutic treatment revealed statistical evidence for predisposition to heavy or light infection (relative to the average level in the overall population). Analyses of associations between the abundances of the four species of nematodes within a combined sample of 525 worm burdens showed significant correlations between 5 out of the 6 possible pair-wise comparisons between species. The relevance of these results to the design of control programmes based on chemotherapeutic application is discussed.
The regulation ofOstertagia ostertagipopulations in calves: the effect of past and current experience of infection on proportional establishment and parasite survival
Authors: Grenfell B. T. , Smith G. , Anderson R. M. 
Published: June 2009

SUMMARYA mathematical model of the parasitic phase of the life-cycle ofOstertagia ostertagiin calves is described. The model is used in the re-analysis of previously published data from a long-term trickle infection experiment in which groups of calves were infected daily with graded doses of 3rd-stage (L3) larvae. The results of the analysis are consistent with the hypothesis that the observed changes in the intensity of infection in the calves were the result of a decline in the proportional establishment of ingested L3 larvae, and a rise in the death rate of the 5th-stage worms as the duration of exposure to infection increased. The proportion of ingested L3 larvae that become established in the mucosa can be described as an exponential decay function of the duration of the infection. Within the range of trickle intensities investigated, the function appears to vary independently of the level of exposure to infection. In contrast, the rate of mortality of the 5th-stage worms appears to be an increasing linear function of the total cumulative number of 3rd-stage larvae administered.
The regulation ofOstertagia ostertagipopulations in calves: density-dependent control of fecundity
Authors: Smith G. , Grenfell B. T. , Anderson R. M. 
Published: June 2009

SUMMARYThe decline in faecal egg counts, characteristic of calves which have been experimentally infected withOstertagia ostertagi, is analysed using a mathematical model in which parasite fecundity is assumed to be an inverse function of both the duration and intensity of infection. The model incorporates a description of the frequency distribution of mature parasites between hosts (which is less over-dispersed than is usual for many other helminth infections). The model provides a good overall description of the decline in faecal egg production observed during trickle and single infection experiments. The main discrepancy between a comparison of the model predictions and the results of the most detailed available series of trickle infection experiments occurs at the initial peak of egg production. The magnitude of this difference appears to be related to the worm burden at the peak of egg production. The possible mechanisms underlying density-dependent regulation of the fecundity ofO. ostertagiaare discussed.
Population biology ofOstertagia ostertagiand anthelmintic strategies against ostertagiasis in calves
Authors: Smith G. , Grenfell B. T. , Anderson R. M. , Beddington J. 
Published: June 2009

SUMMARYFive chemoprophylactic or chemotherapeutic strategies against bovine ostertagiasis are compared using a mathematical model of the population biology ofOstertagia ostertagi. The model offers a means of screening novel strategies prior to their further investigation in the field. Under conditions of climate and management typical of many regions in Northern temperate Europe, the model indicates that all of the tested prophylactic strategies will result in a profound reduction in the intensity of infection in grazing beef calves when compared with an untreated control group or the simple therapeutic protocol. Not all of those strategies which caused diminution in the scale of the midsummer rise in pasture larval contamination resulted in progressively less contaminated pastures in subsequent years. Moreover, the reproductive potential of the parasite is so great that the principal advantage of the ‘pasture cleaning’ effect that is the consequence of some protocols is not that the pasture may eventually be used to graze untreated calves but that the treated animals are subjected to a progressively smaller parasitic challenge with the concomitant pay-off in production gains.