bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of proteins synthesizedin vitroby the erythrocytic stages ofPlasmodium knowlesi
Authors: McColm A. A. , Shakespeare P. G. , Trigg P. I. 
Published: June 2009

SUMMARYStudies were performed to identify specific parasite proteins synthesized withinPlasmodium knowlesi-infected rhesus erythrocytes. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of whole parasites freed from the host erythrocyte by immune lysis, of membranous and cytoplasmic parasite fractions, and of isolated merozoites, detected several parasite-specific components after Coomassie Blue staining of the separated proteins. However, significant contamination with host erythrocyte material generally occurred, particularly in the whole parasite and parasite membrane preparations. Improved identification of plasmodial proteins was subsequently afforded by a radioisotope labelling technique in which parasitized erythrocytes were cultivatedin vitrowith [3H] isoleucine prior to electrophoretic analysis. Of 11 principal labelled peaks ranging in molecular weight from approximately 17000 to 145000 which were detected upon electrophoresis of whole parasites harvested from culture, all were observed in the cytoplasmic fraction while at least 5 were also associated with the membranous cell fraction. Analysis of different developmental stages of the intra-erythrocytic parasite revealed no significant stage-specific qualitative variations in the electrophoretic profiles. Quantitatively, however, the middle to late trophozoites incorporated more [3H] isoleucine into protein than the other intra-erythrocytic stages. Analysis of merozoites purified from labelled schizonts showed a protein pattern similar to the other stages. This confirmed that host components did not contribute to the labelling pattern and that none of the labelled proteins were specific to the residual cytoplasm remaining after merozoite formation.
Release of radio-isotope labelled antigens fromPlasmodium knowlesiduring merozoite re-invasionin vitro
Authors: McColm A. A. , Trigg P. I. 
Published: June 2009

SUMMARYLabelled antigens sharing determinants with both membrane and cytoplasmic fractions ofPlasmodium knowlesiwere detected in culture medium afterin vitroincubation of schizont-stage parasites previously pulse-labelled with [3H]isoleucine. Release of antigens occurred only during schizont rupture and merozoite re-invasion. Antigenic material accounted for up to a third of the total trichloroacetic acid-insoluble radioactivity released by the cells. Absorption experiments indicated that approximately two-thirds of this antibody-precipitable material shared determinants with parasite membrane antigens, with a similar quantity sharing determinants with cytoplasmic proteins. Using antisera derived against 2 different antigenic variants ofP. knowlesi, no evidence for the release of variant-specific antigens was obtained. Centrifugal analysis revealed that the majority of the radio-isotope labelled antigens were particulate in nature; however, some appeared to exist in true solution.
The contribution ofAscaris lumbricoidesto malnutrition in children
Authors: Stephenson Lani S. 
Published: June 2009

SUMMARYThere is a need for more applied and experimental research to determine more precisely the relationships between nutrition, particularly childhood malnutrition, and intestinal parasitic infections, particularlyAscarisinfection. Nevertheless, it is clear that in certain communitiesAscarisinfection is associated with poor growth in malnourished children and that deworming improves growth. Periodic deworming of children using a mass treatment approach may be needed to control soil-transmitted helminths in areas where parasites and protein energy malnutrition are highly prevalent. The main aims of treatment should be to reduce parasite loads below the level of clinical significance for the individual child and to reduce future environmental contamination with infective faeces for the sake of the community.
Schistosoma mansoni: development of primary infections in mice genetically deficient or intact in the fifth component of complement
Authors: Ruppel A. , Rother U. , Diesfeld H. J. 
Published: June 2009

SUMMARYThe influence of the late components of complement (C) on percutaneous primary infections withSchistosoma mansoniwas studied in inbred mice genetically deficient or intact in C5. Worm recoveries were diminished in C5-deficient male mice as compared to C5-intact animals. Twenty-four-day-old parasites were also shorter following growth in C5-deficient animals. At 7 weeks after infection, female schistosomes, but not male parasites, were shorter and fewer eggs/schistosome pair were deposited in the livers of C5-deficient as compared to C5-intact male mice. In addition to the presence of C5, the mouse sex was found to influence the outcome of an infection. Schistosomes showed a reduced infection rate and were relatively stunted after 24 days of growth in female mice of the two strains as compared to male mice of the corresponding strains. The results suggest that C5 plays no role in defence against a primary infection in mice.
Processes influencing the distribution of parasite numbers within host populations with special emphasis on parasite-induced host mortalities
Authors: Anderson R. M. , Gordon D. M. 
Published: June 2009

SUMMARYThe paper examines the factors which generate various patterns of dispersion in the distribution of parasites within their host populations. Particular emphasis is placed on the role played by chance elements in the growth and decay of parasite populations and on the influence of different types of demographic processes. It is argued that observed distributions are dynamic, rather than static, entities generated by opposing forces, some acting to create over-dispersion and others acting to generate under-dispersion. Monte Carlo simulation experiments, based on probability models of the growth and decay of host and parasite populations, are used to study the dynamics of parasite dispersion. Attention is specifically focused on the role played by parasite-induced host mortality. It is shown that, for certain types of host–parasite associations, convex curves of mean parasite abundance in relation to age (age-intensity curves), concomitant with a decline in the degree of dispersion in the older age classes of hosts, may be evidence of the induction of host mortality by parasite infection. Empirical evidence is examined in light of this prediction. In general, however, simulation studies highlight the technical difficulties inherent in establishing clear evidence of parasite-induced host mortality from ecological studies of hosts and parasites in their natural habitats.
Characterization of surface proteins and glycoproteins on red blood cells from mice infected with haemosporidia:Babesia rodhainiinfections of BALB/c mice
Authors: Howard R. J. , Smith Patricia M. , Mitchell G. F. 
Published: June 2009

SUMMARYInfection of intact (nu/+) or hypothymic (nu/nu) BALB/c mice with the lethal intra-erythrocytic parasite,Babesia rodhaini, induced several changes in the surface proteins of red cells from infected blood. Lactoperoxidase-catalysed radio-iodination was used to compare the surface proteins on normal mouse erythrocytes and the total red cells from infected blood at different levels of parasitaemia. At very low parasitaemia, when only 2·5% of the red cells contained parasites, we observed significant changes in the profile of radio-iodinated proteins separated by SDS-polyacrylamide gel electrophoresis. These changes included the appearance of a group of high molecular weight proteins, and a protein with an apparent molecular weight (Mr) of 60 000, both of which were absent from normal erythrocytes. The major labelled band on the erythrocyte surface (Mr92 000) also appeared to be less heavily labelled during infection. The magnitude of these differences in surface proteins increased as the parasitaemia rose, until the new bands dominated the radioactivity profile with blood of greater than 50% parasitaemia. Several control experiments established that the radio-iodinated proteins were surface molecules on intact cells and that artifactual proteolysis did not contribute to the observed differences. The results suggest that changes in the surface proteins occur onallred cells in the blood of infected mice. The results of labelling the surface glycoproteins by oxidation with periodate or galactose oxidase, followed by NaB3H4reduction, have varied with the isolate ofB. rodhaini. With the isolate currently in use, no significant differences were observed in the labelled surface glycoproteins of normal erythrocytes and red cells from infected blood of high parasitaemia, whereas an earlier isolate exhibited a marked decrease of glycoprotein labelling of both infected and uninfected red cells.
Characterization of surface proteins and glycoproteins on red blood cells from mice infected with haemosporidia:Plasmodium bergheiinfections of BALB/c mice
Authors: Howard R. J. , Smith Patricia M. , Mitchell G. F. 
Published: June 2009

SUMMARYThe surface proteins and glycoproteins of red cells fromPlasmodium berghei-infected blood have been radio-isotope labelled and compared with those of normal mouse erythrocytes using the following protein labelling probes: lactoperoxidase-catalysed radio-iodination of tyrosyl residues, periodate oxidation and NaB3H4reduction of sialic acid and oxidation of galactosyl/N-acetylgalactosaminyl residues by galactose oxidase with subsequent NaB3H4reduction. DuringP.bergheiinfection, new tyrosyl-labelled proteins with apparent molecular weights (Mr) of 60000, 54000, 40000 and 27500 appeared on the surface of most, if not all, red cells in the blood. Purified multinucleate cells (mostly reticulocytes) differed only in that they also had a surface protein withMrof 83000. However, this molecule is thought to be specific to mouse reticulocytes rather than derived from parasites. In contrast to the relatively minor changes detected with radio-iodination, striking changes inglycoproteinradio-isotope labelling resulted from infection. All of the red cells in infected blood of greater than 20% parasitaemia lost their periodate-sensitive glycoprotein sialic acid. With some samples there was little change in glycoprotein labelling by the galactose oxidase method, provided neuraminidase was also added. Modification of the exocyclic hydroxyls of sialic acid is postulated to account for this. Other blood samples exhibited a dramatic loss of galactose oxidase-dependent labelling. It is suggested that these observations may relate to the excessive red cell destruction of uninfected as well as infected cells which has been inferred in many haemosporidial infections, including malaria.
Characterization of surface proteins and glycoproteins on red blood cells from mice infected with haemosporidia:Plasmodium yoeliiinfections of BALB/c mice
Authors: Howard R. J. , Smith Patricia M. , Mitchell G. F. 
Published: June 2009

SUMMARYLactoperoxidase-catalysed radio-iodination was used to compare the surface proteins on red cells fromPlasmodium yoelii-infected and normal BALB/c mice. The profile of radio-iodinated proteins separated by SDS-polyacrylamide gel electrophoresis was different for infected blood of similar parasitaemia from mice inoculated with different doses of the parasite. Inoculation with the lower dose resulted in the appearance of a major radio-iodinated protein of apparent molecular weight (Mr) 76000 which was labelled to a similar extent on uninfected red cells from infected blood and purified multinucleate infected cells. Several minor radio-iodinated bands, with identical mobilities to the minor bands on normal BALB/c erythrocytes, were also present on red cells from this infected blood. In contrast, the higher inoculation dose produced changes in the minor labelled bands, and the band withMrof 76000 was absent. In this case, the minor radio-iodinated proteins of the normal BALB/c erythrocyte (with Mr of 65000, 57000, 48000, 38000 and 32000) were replaced by a series of bands withMrof 60000, 50000, 43000 and 28000 on both uninfected and infected red cells. These differences with inoculation dose may be related to the different duration of these infections, the development of anaemia and the extent of pathological changes at the erythrocyte surface.P. yoeliiinfection caused a marked loss in periodate-dependent labelling of sialoglycoproteins on most, if not all, red cells in infected blood. There was also a large decrease in galactose oxidase-dependent glycoprotein labelling with or without neuraminidase treatment. These changes in the carbohydrate groups on red cell membrane glycoproteins may be linked to the excessive loss of both uninfected and infected red cells during some malaria infections.
The importance of parasite load in the killing ofPlasmodium vinckeiin mice treated withCorynebacterium parvumor alloxan monohydrate
Authors: Cox F. E. G. , Millott Stephanie M. 
Published: June 2009

SUMMARYMice pre-treated withCorynebacterium parvumand later challenged withPlasmodium vinckeibecome infected but do not die whereas control mice do. When pre-treated mice were challenged with 1, 10, 1 × 102, 1 × 104, 1 × 105or 1 × 106parasites, the pre-patent periods correlated directly with the number of parasites injected, but the subsequent parasitaemias reached similar levels. This suggests that parasite killing, resulting from pre-treatment withC. parvum, is not triggered until the parasite load has reached a particular threshold. The injection of alloxan monohydrate, which brings about the release of toxic oxygen inter mediates thought to be involved in non-specific immunity, has little effect onP. vinckeiinfections until the parasitaemia is relatively high. This indicates that oxygen-mediated parasite killing also does not occur until the parasitaemia has reached a particular threshold. It is suggested that it is only at relatively high parasitaemias that the factors involved in parasite killing are able to enter the infected red blood cells.
Comparison of protein composition between schistosomula ofSchistosoma japonicumandS. mansoni
Authors: Maeda S. , Irie Y. , Yasuraoka K. 
Published: June 2009

SUMMARYSDS-PAGE analysis revealed that the protein composition of mechanically transformed schistosomula (ms) of a Japanese strain ofSchistosoma japonicumwas essentially similar to that of a Philippine strain ofS. japonicum. However, the protein components ofS. mansonims were remarkably different from those ofS. japonicum. Specific proteins of Mr60–65.and 30 kDa were found in ms ofS. japonicumandS. mansoni, respectively. In skin-penetrated schistosomula (ss) of the two species, a common protein of 67 kDa was detected. Using two-dimensional electrophoresis, strain-specific polypeptides (9 in a Japanese and 11 in a Philippine strain) were identified in ms ofS. japonicum. Mechanically transformed and skin-penetrated schistosomula ofS. japonicum(Japanese) had, respectively, 7 and 10 specific proteins. Four and 1 specific polypeptides were also detected in two-dimensional profiles of ms and ss ofS. mansoni, respectively.
An ultrastructural analysis of cyst wall development in the metacestode ofHymenolepis diminuta(Cestoda)
Authors: Sylvia Richards K. , Arme C. 
Published: June 2009

SUMMARYA series of development stages (I–XI) have been devised to describe the development of the cyst wall of the metacestode ofHymenolepis diminuta. The cyst wall possesses tegumentary, muscular, fibrous and inner cyst tissues, the developmental rates and differentiation patterns of which are not identical. The tegumentary tissue differentiates posteriorly. Its microvillus-bearing distal cytoplasm remains simple until scolex retraction, after which rapid increase in depth followed by vacuolation occurs and basal membrane infoldings surround Phase 3 fibrogenesis fibrils. Senescence, which also affects the tegumentary cytons, then ensues. The muscle system development is posteriad and maturation, completed before scolex retraction, is followed by myocyton senescence. Posteriorly differentiated fibroblasts commence Phase 1 fibrogenesis after scolex retraction and the primary fibrous zone is fully established within approximately 6 days. Phase 2 and 3 fibrogenesis develop centrifugally, the fibrils of Phase 2 surrounding the tegumentary cytons and myocytons prior to their senescence, and those of Phase 3 lying more peripherally. The inner cyst tissue, established posteriorly, differentiates anteriorly, centripetally and early, the penultimate stage commencing just before scolex retraction, about 6 days after which the final maturation junctional complexes start development. Neitherin vitroexcystment nor infectivity of the definitive host can be satisfactorily achieved before the initial development of the primary fibrous zone. This may play a skeletal role during excystment, and is shown to be unaffected by the digestive enzymes which cause loss of cytoplasmic integrity in the outer regions of the cyst.
The rostellar tegumentary cytoplasm of the metacestode ofHymenolepis diminuta(Cyclophyllidea: Cestoda)
Authors: Richards K. Sylvia , Arme C. 
Published: June 2009

SUMMARYPrior to scolex-retraction, the tegumentary syncytial cytoplasm of the presumptive rostellar region ofHymenolepis diminuta(fromTenebrio molitorkept at 26 °C) is indistinguishable from that of the rest of the cysticercoid. At 1 day after scolex-retraction differentiation of the rostellum has commenced, the tegumentary cytoplasm containing a small number of membrane-bound, ovoid, electron-dense granules which are absent from all other tegumentary regions of the metacestode. By 3 days after scolex-withdrawal there is a substantial increase in the number of ovoid granules within the rostellar tegumentary syncytium and the Golgi systems of the rostellar cytons are highly secretory. At this stage, although the cyst wall tissues are not fully developed, the metacestode is infective. This early and rapid development of the rostellar region presumably enables the ‘adult’ condition to be readily attained. In older metacestodes there is a progressive accumulation of ovoid granules within the rostellar tegumentary cytoplasm, accompanied by a decrease within the rostellar cytons. At 23 days following scolex-retraction the rostellar syncytium has the appearance of that of the adult tapeworm. The rostellar cytons also produce tegumentary discs and vesicles and are therefore regarded as homologous to the other tegumentary cytons of the metacestode.
Hymenolepis nana: the fine structure of the adult nervous system
Authors: Fairweather I. , Threadgold L. T. 
Published: June 2009

SUMMARYThe fine structure of the nervous system in the scolex and neck region of Hymenolepis nana has been investigated by transmission electron microscopy. A description of the gross neuroanatomy in these regions of the worm is presented. The ganglia, commissures and nerve cords consist of an incomplete cortex of nerve cell bodies, and a core of nerve fibres. A delimiting sheath or capsule is absent. The nerve cell bodies contain a single nucleus with a single nucleolus, mitochondria, many ribosomes, Golgi complexes and vesicles formed within the Golgi cisternae. Numerous sub-surface cisternae are present beneath the outer plasma membrane of the nerve cell body, and the inner surfaces of these cisternae are studded with ribosomes. Some of the cisternae run tangentially into the cytoplasm of the perikaryon, particularly in the vicinity of the Golgi complexes; both sides of these cisternae are studded with ribosomes. From each neuronal perikaryon arise one or more neurites that contain neurotubules, mitochondria, ribosomes and electron-lucent or dense-cored vesicles. Five types of vesicle have been distinguished on the basis of their size and content. The neurites are unmyelinated and form synapses in the neuropile; the synapses possess features typical of those where mechanical strength is of importance. Three types of sensory receptors have been observed in H. nana, two ciliated and one non-ciliated; the latter typically form double or triple nerve endings which terminate within the tegument.
Destruction ofLeishmania mexicana amazonensis amastigotesby leucine methyl ester: protection by other amino acid esters
Authors: Alfieri Silvia C. , Zilberfarb V. , Rabinovitch M. 
Published: June 2009

SUMMARYl-Amino acid esters, such as leucine methyl ester (Leu-OMe) can destroy intracellular as well as isolated amastigotesof Leishmania mexicana amazonensisby a mechanism which may involve ester hydrolysis by parasite enzymes. We show here that several other esters prevented the killing of the amastigotes by Leu-OMe. Destruction ofLeishmaniawithin macrophages in culture was assessed microscopically and viability of isolated parasites was monitored by reduction of the tetrazolium MTT. The main features of the protective effect were similar for intracellular and for isolated amastigotes. Thus, (i) effective prevention of parasite killing required that the protective ester be present in the medium prior to and during exposure of infected cells or parasites to Leu-OMe; (ii) the same esters protected intracellular and isolatedLeishmaniaagainst damage by Leu-OMe. Ranks of protective activity, as determined on isolated amastigotes were: Gly-OBz > Tyr-OMe > Ile-OMe > Met-OMe > Val-OMe > Ala-OMe > Gly-OMe > D-Leu-OMe; (iii) several esters were inactive in both systems (Leu-OBz, Trp-OMe and Phe-OMe). Protective activity was associated with leishmanicidal (e.g. Gly-OBz, Tyr-OMe) as well as with non-leishmanicidal (e.g. Ile-OMe, Val-OMe) esters. The results are compatible with the hypothesis that protective esters inhibit the activity of parasite enzyme(s) which hydrolyse Leu-OMe.
Analysis and comparison of immune reactivity in guinea-pigs immunized with equivalent numbers of normal or radiation-attenuated cercariae ofSchistosoma mansoni
Authors: Rogers M. V. , McLaren Diane J. 
Published: June 2009

SUMMARYGuinea-pigs immunized with equivalent numbers of normal or radiation-attenuated cercariaeof Schistosomamansoniare known todevelop close to complete resistance to reinfection at weeks 12 and 4·5 respectively. We here analyse and compare the immune responses induced by the two populations of cercariae. Both radiation-attenuated and normal parasites ofS. mansonielicited an extensive germinal centre response in guinea-pigs by week 4·5 post-immunization. The anti-parasite antibody titre and cytotoxic activity of serum from 4·5-week-vaccinated, or 4·5-week-infected guinea-pigs were approximately equal, but sera from 12-week-infected individuals had high titres of anti-parasite antibody, which promoted significant larvicidal activityin vitro.In all cases, larvicidal activity was mediated by the IgG2 fraction of the immune serum. Lymphocyte transformation tests conducted on splenic lymphocytes from 4–5-week vaccinated guinea-pigs revealed maximal stimulation against cercarial, 2-week and 3-week worm antigens, whereas spleen cells from 4–5-week-infected guinea-pigs were maximally stimulated by cercarial and 6-week worm antigens. The splenic lymphocyte responses of 12-week infected animals were dramatic against antigens prepared from all life-stages of the parasite.