bluuebunny/crossref_metadata_2025_split huggingface dataset:
Schistosoma mansoni: evidence for a role of serum factors in protecting artificially transformed schistosomula against antibody-mediated killing in vitro
Authors: Tavares C. A. P. , Soares Rita C. , Coelho P. M. Z. , Gazzinelli G. 
Published: June 2009

SummaryArtificially transformed schistosomula of Schistosoma mansoni develop a consistent but small protection against the lethal effects of antibody plus complement when cultured for 24 h in a chemically defined medium. In contrast, they become rapidly resistant to antibody plus complement, when cultured in the presence of a complex medium consisting of equal parts of heat-inactivated rabbit serum and Earle's/lactalbumin or in defined medium supplemented with small amounts of heat-inactivated rabbit serum. Sephadex G-200 gel filtration revealed that the protective factor in rabbit serum is a macromolecule with a molecular weight between 7 and 19S. Parasites cultured at 10 °C or in the presence of 200 μg of puromycin show less serum-induced protection against the lethal effects of antibody plus complement than do controls.
Infections with blood parasites in the small British rodentsApodemus sylvaticus,Clethrionomys glareolusandMicrotus agrestis
Authors: Healing T. D. 
Published: June 2009

SUMMARYThree populations of small wild British rodents were studied by capture–recapture methods over a period of 3 years, a fourth group was studied for 1 year and a fifth was sampled annually for 4 years. Blood smears were taken from 3 species of rodents: the woodmouseA podemus sylvaticus, the bank voleClethrionomys glareolus(and an island sub-speciesC.g. skomerensis) and the short-tailed voleMicrotus agrestis. The smears were examined microscopically. Four genera of haemoparasitesBabesia, Hepatozoon, TrypanosomaandGrahamellawere detected.Babesiawas absent fromC.g. skomerensis, Hepatozoonwas rarely found inA. sylvaticusandM. agrestisandTrypanosomawas rare inA. sylvaticus. More males were infected than females but the difference was only statistically significant for the infection withHepatozoonin adultC.g. skomerensis. Infections withBabesiaandHepatozoonwere more prevalent in adult animals and infections withTrypanosomawere more prevalent in younger individuals. Only inC.g. skomerensiswas there a significant difference between age classes in the prevalence of infection withGrahamella– there being more adults infected. Concurrent infections were detected,Hepatozoonbeing the parasite most commonly involved. The prevalence of infections was found to be approximately proportional to the number of animals known to be alive, regardless of the season.
Ultrastructural evidence for complement and antibody-dependent damage to schistosomula of Schistosoma mansoni by rat eosinophils in vitro
Authors: McLaren Diane J. , Ramalho-Pinto F. J. , Smithers S. R. 
Published: June 2009

SummaryRat peritoneal eosinophils adhere to live Schistosoma mansoni schistosomula in vitro in the presence of fresh normal rat serum, or in heat-inactivated serum from rats immune to the parasite. When the eosinophils are present in sufficient numbers the worms show ultrastructural evidence of surface damage and are ultimately killed. It is believed that the appearance of focal lesions in the tegument of the schistosomulum follows the secretion of enzymes by the eosinophils onto the parasite surface. The cells have been observed within these lesions and later between the basal plasma membrane of the tegument and the underlying interstitial material. It is suggested that the cells are responsible for prising the tegument away from the body of the worm. The detached tegument shows evidence of further degradation. Adherent eosinophils which have released their secretions appear to degenerate and are eventually replaced by macrophages. Remnants of both the expended eosinophils and the disrupted tegument have been identified within the macrophages. Adherence of eosinophils through C3–C3 receptor interaction results in earlier and more severe damage to the schistosomula than when adherence occurs through Fe receptors. Rat eosinophils also adhere to C3-coated, glutaraldehyde-flxed schistosomula and C3-coated Sepharose beads. However, evidence of enzyme secretion is only obtained when the target is a schistosomulum.
Laboratory comparison of the relative success of Biomphalaria glabrata stocks which are susceptible and insusceptible to infection with Schistosoma mansoni
Authors: Minchella D. J. , Loverde P. T. 
Published: June 2009

SUMMARYA method of interrupting the life-cycle of the human blood fluke Schistosoma by increasing the proportion of genetically insusceptible intermediate host snails in natural populations was first proposed nearly 25 years ago. The method assumes that insusceptible snails will be at a selective advantage over susceptible snails when the schistosome parasite is present, and therefore natural selection will act to increase the proportion of alleles for insusceptibility. A major objection to the proposed technique is ‘If insusceptible snails are at a selective advantage, then why are they not predominant in natural populations that transmit disease?’ One explanation of this paradox is that insusceptibility may be associated with a disadvantageous character or a physiological defect. This study tests this hypothesis by measuring the relative reproductive success of susceptible and insusceptible snails under controlled conditions. Results indicate that insusceptible (unsuitable) snails are negatively affected in the presence of either susceptible snails or schistosome parasites. Furthermore, in the presence of both susceptible snails and schistosome parasites, insusceptible snails are selectively disadvantaged compared to susceptible snails. These results obtained under laboratory-controlled conditions suggest a plausible answer as to why insusceptible snails are not predominant in natural populations that transmit disease.
Retarded development of Schistosoma mansoni in immunosuppressed mice
Authors: Harrison R. A. , Doenhoff M. J. 
Published: June 2009

SUMMARYPrevious observations, which showed that treatment of mice with hydrocortisone acetate around the time of their infection with Schistosoma mansoni reduced the mature worm burden, have been confirmed. The number of eggs produced by the surviving worms during early patency was also significantly reduced. Cyclophosphamide and another steroid immunosuppressant, betamethasone, also caused a reduction in fecundity of S. mansoni when given at the time of infection, as did T-cell deprivation of the mice by adult thymectomy and injection of anti-thymocyte serum 1 month before infection. There was no effect of these three treatments on worm numbers. In contrast, injection of mice with anti-thymocyte serum at the time of infection marginally increased the size of the mature worm burden. The deleterious effects of hydrocortisone acetate on S. mansoni worm numbers and fecundity were only apparent if the steroid was given within 1 week of infection. Indomethacin, a compound which inhibits tissue inflammatory reactions by inhibiting prostaglandin synthesis, and which therefore mimics one of the actions of corticosteroids, had no effect on S. mansoni worm maturation and fecundity.
Nippostrongylus (Nematoda) in protein-malnourished rats: host mortality, morbidity and rehabilitation
Authors: Keymer Anne , Crompton D. W. T. , Walters D. E. 
Published: June 2009

SUMMARYThe synergistic relationship between host nutrition and the effects of Nippostrongylus was investigated experimentally in rats fed a diet containing 1% (w/w) protein. Rats were infected with 10 doses of N. brasiliensis varying from 0.35 to 99 larvae/g and their daily food intake and weekly body mass were compared with those of uninfected rats fed the same diet for a period of 9 weeks. The deterioration of the uninfected rats observed as a result of protein-energy malnutrition was found to be accelerated in a dose-dependent manner in the rats infected with N. brasiliensis. Analysis of food intake and body mass measurements demonstrated that this acceleration was related to a decrease in food intake and indicated a likely alteration in nutrient utilization, both of which were established by the end of the first week of the infection. Remission from the combined effects of malnutrition and infection was achieved by offering the rats a high-protein diet (20% w/w), whereupon rehabilitation was found to be complete within a period of 9 days. The implications of the results and the possible mechanisms involved in their generation are discussed in relation to the frequent coexistence of helminthiasis and malnutrition.
Ovoviviparity in platyhelminth life-cycles
Authors: Tinsley R. C. 
Published: June 2009

SUMMARYThe encapsulated embryos of platyhelminths may be retained and complete their developmentin uteroin a range of circumstances. However, hatching within the parent (the criterion of ovoviviparity) is relatively rare and larvae generally emerge only after deposition. Viviparity is characterized by the nutritional dependency of the unencapsulated larva upon the parent, but in several cases larvae retained within a shell also receive parental nutrients during intra-uterine development. Uptake of exogenous nutrients via shell pores occurs inSchistosoma mansonibut the eggs, which gain all the advantages of intra-uterine retention, are supported by host nutrients.Intra-uterine larval development avoids the hazards of development in the external environment and eliminates the time delay between oviposition and infection. Deposition of immediately infective offspring may be concentrated in time and space to exploit periods of host vulnerability. The control and precision of transmission is illustrated by examples in which the opportunity for invasion is restricted because of either host behaviour or environmental instability. This strategy has been an important factor in the evolution of polystomatid monogeneans, and its effectiveness is demonstrated by comparison of the life-cycles ofPolystoma integerrimumandPseudodiplorchis americanus. Ovoviviparity also increases reproductive potential in some polystomatids by extending the period of multiplication and by increasing established populations through internal re-infection. InEupolystoma alluaudi, the capacity for ovoviviparity is programmed into larval development and this regulates population growth within individual hosts.
The isolation and characterization of a Babesia from red deer (Cervus elaphus)
Authors: Adam Katherine M. G. , Blewett D. A. , Brocklesby D. W. , Sharman G. A. M. 
Published: June 2009

SummaryOn three occasions, antibody positive blood from wild red deer produced overt infections with Babesia when inoculated into splenecto-mized red deer. One of the deer also became infected with Eperythrozoon sp. Babesia divergens, B. capreoli and the Babesia of red deer are morphologically similar and the marginal position of the parasites in the host cell is characteristic. Babesia were not seen and no antibody was formed in five out of six splenectomized bovine calves which were injected with parasitaemic red deer blood. Two of these calves when challenged with B. divergens were fully susceptible. A transient infection with the deer Babesia may have occurred in the sixth calf since antibody was detected and the animal resisted challenge with B. divergens.In indirect fluorescent antibody tests there was little or no difference in the titre of sera from naturally or experimentally infected cattle and deer when reacted with B. divergens or the red deer Babesia antigens. Despite their similarities, specific status for B. divergens and the red deer Babesia is probably justified; at present there is insufficient evidence to justify separation of the red deer Babesia from B. capreoli.
Linked metabolism of L-serine and L-alanine by Moniliformis moniliformis (Acanthocephala) in vitro
Authors: Ward P. F. V. , Crompton D. W. T. 
Published: June 2009

SUMMARYExperiments to investigate the linked metabolism of L-serine and L-alanine by Moniliformis moniliformis in vitro were carried out by incubating adult worms aerobically for 3 h at 37 °C in Tyrode’s solution containing L-[U-14C]alanine and other amino acids. When present in the medium alone, alanine was totally removed by the worms and metabolized almost entirely to ethanol and a compound identified as carbon dioxide. When present in the medium with serine and no other amino acids, alanine was largely metabolized as before but additional alanine, believed to originate from serine, was excreted. The same results were obtained with serine and 16 other amino acids in the incubation medium.
Echinococcus granulosus: in vitroeffect of monensin on the tegument of the protoscolex
Authors: Rogan M. T. , Richards K. Sylvia 
Published: June 2009

SUMMARYProtoscoleces ofEchinococcus granulosuswere incubated in a 10 μm solution of monensin and their viability and the ultrastructure of their tegument were monitored over a 36 h period. The earliest effects of the lonophore, apparent within 15 min, involved a degree of cisternal swelling of the tegumentary Golgi complexes. Swelling became more pronounced with time and cytons eventually contained numerous large electron-lucent vesicles. Residual bodies indicative of autophagy were observed in the cytons and distal cytoplasm from 1 h onwards. All movement of protoscoleces ceased after 1 h and the surface of the soma subsequently became folded, possibly suggesting spastic paralysis. Later, vacuoles and large cytoplasmic blebs were observed in the distal cytoplasm and viability dropped rapidly after 12 h. All protoscoleces were dead at 36 h. The potential of monensin as anin vivoprotoscolicidal agent is discussed.
Studies on two new species of Microsporida hyperparasitic in adultAllocreadium fasciatusi(Trematoda, Allocreadiidae)
Authors: Canning Elizabeth U. , Madhavi R. 
Published: June 2009

SummaryThe vegetative and sporogonic stages ofUnikaryon allocreadiisp. nov. andNosema giganticasp. nov., from the parenchyma of adult flukes,Allocreadium fasciatusiin the gut of the freshwater fishAplocheilus melastigmafrom India, are described and figured.U. allocreadii, which is uninucleate throughout development and is disporoblastic, differs fromU. legeriin that it occurs in adult flukes from a freshwater host.N. giganticahas diplokaryon nuclei, at least in the sporogonic stages, and is much larger than all other microsporidia in platyhelminths.Hatching of the spores and patholgenicity are described and the mode of transmission to the flukes is discussed. Infected flukes, which are sluggish and opaque, are often displaced from the normal site of infection.
Studies to determine the taxonomic status of Eimeria mitis, Tyzzer 1929 and E. mivati, Edgar and Seibold 1964
Authors: Shirley M. W. , Jeffers T. K. , Long P. L. 
Published: June 2009

SUMMARYWe have examined several taxonomic features of a number of strains of Eimeria from many sources world wide. The strains were isolated on the basis of their small spherical (or sub-spherical) oocysts. From a study of mean oocyst dimensions, electrophoretic variation of enzymes, ability to develop in embryonated eggs, absence of gross lesions in heavily infected chickens, and cross-immunity, all the strains were found to belong to one species. For convenience, the parasites when isolated, were referred to as strains of E. mitis/mivati-type, but after characterization they were clearly found to be E. mitis. In contrast, a laboratory strain of E. mivati supplied to one of us (M.W.S.) was found to be a mixture of E. acervulina and E. mitis. Evidence from these and other studies supports the notion that E. mivati is a nomina dubia.
Host cell invasion by Apicomplexa: an expression of the parasite's contractile system?
Authors: Russell D. G. 
Published: June 2009

SUMMARYRecent studies on the motility of coccidian sporozoites have demonstrated a membrane-associated contractile system capable of moving certain intramembraneous components down the parasite surface propelling it forwards. The properties of this system resemble recorded observations on host cell invasion. In this study the invasive behaviour ofEimeria tenellaandE. acervulinahas been examined, with reference to the above findings, by light microscope and scanning and transmission electron microscopes. Known inhibitors of motility prevent invasion, though attachment appears unaffected. Invasion itself consists of 3 phases; attachment and orientation, induction of a parasitophorous vacuole and translocation of the parasite into the vacuole. Ultrastructural examination reveals a close membrane/membrane association maintained throughout invasion. From these results it is suggested that the parasite enters the parasitophorous vacuole by ‘capping’ the host/parasite junction down its body, so locomoting into the host cell. Such a model has two main advantages; it requires no additional modifications to either cell, and the specificity of membrane receptors would enable the one membrane-associated contractile system to be responsible for locomotion, antibody capping and host cell invasion.
The structure of the mature oocyte and zygote of Corynosoma semerme (Acanthocephala)
Authors: Peura Raija , Valtonen E. Tellervo , Crompton D. W. T. 
Published: June 2009

SummaryObservations made with the transmission electron microscope are described from the free ovaries of sexually mature female Corynosoma semerme (Palaeacanthocephala) from the ringed seal (Pusa hispida). The structure of the mature ovaries consists of a supporting syncytium, oogonial cells and tissue and appears to be basically similar to that already described for 4 other species of Acanthocephala representing the 3 orders of the phylum. A comparison has been made between the organization of the cytoplasm of the mature oocyte and the zygote with reference to the consequences of fertilization. A detailed description is presented of the heterogeneous inclusions that are observed in the cytoplasm of the mature oocyte but not in the zygote. The fate and possible function of the components of these inclusions is discussed.
Immunization of mice with gamma-irradiated intramuscularly injected schistosomula of Schistosoma mansoni
Authors: Bickle Q. D. , Taylor M. G. , Doenhoff M. J. , Nelson G. S. 
Published: June 2009

SUMMARYThe parameters involved in the induction of resistance against Schistosoma mansoni by injection of irradiated, artificially transformed schistosomula were studied in mice. Single intramuscular injections of 500 schistosomula exposed to radiation doses in the range 2·3 to 160 krad. resulted in significant protection (in the range 20 to 50% as assessed by reduced worm burdens) against a challenge infection administered at intervals from 3 to 24 weeks post-vaccination. However, schistosomula irradiated with 20 krad. consistently resulted in better protection than those exposed to either higher or lower radiation doses despite the persistence of stunted adults from the infections irradiated with 2·3 krad. Vaccination with 40 krad. schistosomula resulted in significant protection in terms of reduced worm and tissue egg burdens and increased survival following lethal challenge. Varying the number of irradiated schistosomula, the frequency and route of their administration, the site of challenge and the strain of host all failed to enhance the level of resistance. However, percutaneously applied, irradiated cercariae were found to be more effective in stimulating resistance (60%) than intramuscularly injected, irradiated schistosomula (40%).
Gametocytogenesis of Plasmodium falciparum in vitro: the cell-cycle
Authors: Sinden R. E. , Smalley M. E. 
Published: June 2009

SUMMARYReproducible growth of gametocytes of Plasmodium falciparum in vitro was obtained from ring-stages taken directly from naturally infected patients and from the same material following storage in liquid nitrogen. Progressive sexual differentiation in vitro was examined for a finite period of 9 days in microcultures and was, for convenience, divided into 5 stages using established morphological criteria (Hawking, Wilson & Gammage, 1971). This microculture system was adapted as a bioassay for various anti-metabolites. Drug activity was measured by observing the inhibition of the established pattern of sequential development in experimental as compared to control cultures. Inhibitors used were directed against DNA, RNA and protein metabolism and microtubule assembly. As a result of these studies it is proposed that the sexual cell-cycle of P. falciparum is characterized by 4 phases. (1) A G1 period which lasts only a few hours. (2) The S phase, where DNA synthesis occurs, occupies the remainder of the first 2 days of development – both G1 and S are confined to stage I and II gametocytes. (3) G2, which is subdivided into 2 sections: G2A, characterized by stage II and III gametocytes, in which significant RNA and protein synthesis continue to occur; and G2B, where there is a progressive increase in transcription control resulting in the depression of both RNA and protein synthesis. Nonetheless, continued morphological differentiation occurs in the latter section transforming the parasites to stage IV and the morphologically and functionally mature stage V. The final M phase is marked by the brief and explosive events of gametogenesis, during which further protein synthesis occurs de novo. The proposed cell-cycle is examined as a model for studies on the activity of gametocytocidal compounds.
Immunological aspects ofGiardia murisandSpironucleus murisinfections in inbred and outbred strains of laboratory mice: a comparative study
Authors: Brett Sara J. , Cox F. E. G. 
Published: June 2009

SUMMARYThe intestinal flagellates,Giardia murisandSpironucleus muris, cause similar infections in CBA mice as determined by trophozoite and cyst counts. Both parasites occur all along the small intestine withG. muris, being mainly present in the anterior part andS. muristowards the posterior. The early stages of infection are similar in all strains of mice examined and peak levels of both trophozoites and cysts occur 1–2 weeks after infection. All strains of mice overcome the infection but the rate of recovery varies considerably between strains, being most rapid in BALB/c and slowest in A and C57BL.B10. Outbred mice are more variable in their recovery than inbred mice. After recovery, mice are partially resistant to reinfection with the homologous but not the heterologous parasite. Resistance to reinfection withS. murisis greatest in those strains that eliminate the primary infection most rapidly.Giardia murisandS. muriscause similar changes in the mucosa of the small intestine of BALB/c mice with increased intra-epithelial lymphocyte counts from 3 weeks onwards corresponding with the start of the elimination of the parasites from the gut. A reduction in villus height and increase in crypt depth is also characteristic of these infections.
Ethidium bromide: pharmacokinetics and efficacy against trypanosme infections in rabbits and calves
Authors: Gilbert R. J. , Newton B. A. 
Published: June 2009

SUMMARY[14C[ethidium bromide has been used to determine drug levels in tissues and body fluids of rabbits and calves following intramuscular injection. Uninfected andTrypanosoma brucei- orTrypanosoma congolense-infected animals were studied. Blood and tissue fluid levels reached a maximum within 1 h and then fell rapidly; after 96 h 80–90% of the radioactivity injected had been excreted, approximately one third in urine and two thirds in faeces. By 1 h after injection of 1 mg [14C]ethidium/kg into aT. congolense-infected calf, 70–80% of the radioactivity in blood was found to be bound to trypanosomes. Doses of 1 or 10 mg/kg were found not to be curative forT. congolenseorT. bruceiinfections in rabbits; drug treatment resulted in a period of sub-patent parasitaemia which was always followed by a relapse. Examination of the prophylactic action of ethidium in rabbits showed that the drug extended the pre-patent period following trypanosome inoculation but provided no absolute protection. A period of ‘apparent’ prophylaxis observed after drug treatment of infected rabbits has been correlated with the presence of anti-trypanosome IgG in the serum.