bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nippostrongylus brasiliensisin the rat: Failure to relate intestinal histamine and mast cell levels with worm expulsion
Authors: Keller R. 
Published: June 2009

This paper describes experiments to determine whether intestinal tissue mast cells and/or intestinal histamine are involved in the second, expulsive step of worm elimination. In neonatal rats, intestinal tissue contains only very little histamine and mature mast cells are encountered only sporadically. From birth to the adult age, there was a gradual rise in both intestinal mast cells and histamine.DuringNippostrongylus brasiliensisinfection in the adult rat, the concentration of histamine in the small intestine was clearly lower than in uninfected controls.Especially low histamine values were found to occur on days 6–12 of a primary infection in the region where the main worm burden was located. Similarly, the number of tissue mast cells present in the epithelium of the jejunum was decreased in the same region and during the same period of time. From the observation that the bulk of the parasites are expelled at a time when histamme and mast cell levels are low, it was concluded that mast cells and their constituents were not an essential factor in the second step of worm eliminationThis work was supported by the Schweizerische Nationalfonds zur Förderung der wissenschaftlichen Forschung (Grant 5200.3). The skilful technical assistance of Miss I. Beeger, Miss R. Keist and Miss M. Iseli is gratefully acknowledged. I thank Mr H. Berchtold, Biostatistisches Zentrum der Universität Zürich, for the statistical evaluation of the data.
An investigation of the mechanism of infection by digenetic trematodes: the penetration of the miracidium ofFasciola hepaticainto its snail hostLymnaea truncatula
Authors: Wilson R. A. , Pullin P. , Denison Jean 
Published: June 2009

The penetration barrier presented to the miracidium by the snail epithelium can be divided into three layers. The chemical composition and physical configuration of the outermost of these plays an important part in the initial attachment response of the miracidium. Attachment can be stimulated in the absence of the snail by pure chemicals in solution. However, the surface to which the miracidium attaches must have the correct physical configuration otherwise the miracidium is unable to form a stable attachment.In vivo, the miracidial body begins to contract and relax following attachment to the snail. This coincides with the start of secretion by the apical gland and accessory gland cells. The snail's columnar epithelium is rapidly cytolysed so that 10 min after attachment the anterior of the miracidium has reached the underlying connective tissues.As the miracidium penetrates the snail, its ciliated epithelial cells are shed in sequence from anterior to posterior. This shedding removes a protective barrier against osmosis which is probably the acid mucopolysaccharide present in the epithelial cells. The mechanism of shedding is not understood but involves the reversal of binding by the desmosomal mucosubstance which attaches the epithelial cells to surrounding intercellular ridges.The miracidium metamorphoses into the sporocyst as it penetrates the snail, by forming a new body surface. The material for this is extruded from the vesiculated cells which lie beneath the musculature of the body wall. The process of surface formation coincides with cell shedding and moves backwards as cells are shed. At not more than 2·5 h after attachment the extruded cytoplasm forms a thin continuous layer over the surface of the organism. Contacts with underlying cells appear to have been broken and the cytoplasm is underlain by a thin fibrous basal lamella. In the first 24 h after penetration the surface of this syncytium becomes thrown into folds and metamorphosis into the sporocyst can be considered complete.
Interactions between malaria parasites infecting the same vertebrate host
Authors: Richie T. L. 
Published: June 2009

SUMMARYSeveral species of malarial protozoans commonly parasitize the same host population and often the same individual host. This paper reviews the evidence for interactions among such host-sharing parasites. Field studies measuring the cross-sectional prevalence of malarial species often record fewer mixed infections than expected by chance, suggesting that one parasite has excluded another or suppressed its parasitaemia to undetectable levels. Prevalences may vary reciprocally between seasons, with one species increasing in prevalence while another decreases, despite parallel increases in the transmission rates of both, again suggesting suppression of one species by another. However, longitudinal studies of individual hosts indicate that malarial parasites may also favourably affect the host environment for each other, perhaps due to their depressive effect on the immune system: this is shown by the recrudescence of a latent malarial species immediately before or after the parasitic wave of another species. The suppression hypothesis is supported by data derived from the simultaneous inoculation of twoPlasmodiumspecies into laboratory animals; many studies have shown that one or both species are suppressed. This may be mediated by competition for host cells or nutrients, or by heterologous immunity. However, the suppressed species rebounds after the other species has abated, and may show a prolonged infection. Experimental evidence that one species can facilitate the recrudescence of another is minimal, but this may reflect the paucity of investigations of this phenomenon. Laboratory studies show only minor cross-resistance between host-sharing species, which is consistent with the hypothesis that their co-occurrence has led to antigenic divergence or that species showing strong heterologous resistance cannot co-exist in the same host population. Such complementarity occurs not only with the host immune response but also with many other life-history characteristics of host-sharing parasites, such as host cell preference. I conclude that malarial species have been important in each other's evolution, particularly in the tropics where multi-species complexes are common.
The treatment of experimental cutaneous leishmaniasis with liposome-entrapped Pentostam
Authors: New R. R. C. , Chance M. L. , Heath S. 
Published: June 2009

SUMMARYTreatment of cutaneous leishmaniasis by antimonial compounds when administered by various routes to mice infected with Leishmania major or L. mexicana amazonensis is enhanced, relative to the free drug, by entrapment of these compounds within liposomes. The efficacy of the liposome treatment is dependent on the time and route of administration, and upon the phospholipid composition of the liposomes themselves. Drug-loaded liposomes administered intravenously (i.v.) are more effective at reducing the growth of a cutaneous lesion if they are administered after the nodule has begun to develop, rather than at the time of inoculation of the parasites. In contrast to the i.v. route, liposomes administered subcutaneously (s.c.) at the inoculation site are only effective if given at the time of infection.
Antigenic variation in cyclically transmittedTrypanosoma brucei. Variable antigen type composition of metacyclic trypanosome populations from the salivary glands ofGlossina morsitans
Authors: Hajduk S. L. , Cameron Cathy R. , Barry J. D. , Vickerman K. 
Published: June 2009

SUMMARYTsetse flies (Glossina morsitans) were fed on the blood of mice containing any one of 5 variable antigen types (VATs) ofTrypanosoma bruceiAnTAR 1 serodeme. The VATs of the metacyclic trypanosomes subsequently detected in the flies' saliva probes were investigated using monospecific antisera to AnTAR 1 VATs in indirect immunofluorescence and trypanolysis reactions; these sera included 3 raised against AnTats 1.6, 1.30 and 1.45, previously identified as components of the metacyclic population (M-VATs), and against the 5 VATs originally ingested by the flies. The percentage of metacyclics reacting with a particular M-VAT antiserum remained more or less constant (AnTat 1.6, 6·0–8·3%; AnTat 1.30, 13·7–18·2%; AnTat 1.45, 2·0–8·0%), regardless of the age of the fly or the ingested VAT. As these 3 VATs accounted for no more than 30% of the metacyclic population, the existence of at least one more VAT is envisaged. The ingested VAT could not be detected among the AnTAR 1 metacyclic trypanosomes.
Repetitive proteins from the flagellar cytoskeleton of African trypanosomes are diagnostically useful antigens
Authors: Imboden M. , Müller N. , Hemphill A. , Mattioli R. , Seebeck T. 
Published: June 2009

SUMMARYTrypanosome infection of mammalian hosts leads, within days, to a strong early response against a small, distinct number of parasite proteins. One of these proteins is the variable surface glycoprotein (VSG). Most of the others are apparently non-variable, intracellular trypanosome proteins. Two of these antigens I2and I17are now characterized at the molecular level. Both exhibit a highly repetitive amino acid sequence organization, but they show no sequence similarity either to each other or to any other proteins known to date. Preliminary serological analyses indicate that both allow the early, sensitive and specific detection of infections with different species of trypanosomatids, making them interesting candidates for the development of diagnostic tools for trypanosomiasis detection.
Quantifying parameters in the transmission of Babesia microti by the tick Ixodes trianguliceps amongst voles (Clethrionomys glareolus)
Authors: Randolph S. E. 
Published: June 2009

SUMMARYThe estimation of two parameters in the transmission of Babesia microti by the tick Ixodes trianguliceps amongst small mammals, (1) the duration of infectivity in natural hosts and (2) the probability of transmission from an infected to a susceptible vole, is described. When B. microti was maintained by direct tick transmission, the probability of a complete cycle of transmission via the larval-nymphal and nymphal-adult transstadial routes was 1·0 and 0·71 respectively, but only if the larvae or nymphs had engorged, as distinct from feeding slowly, while the source parasitaemia exceeded 2 or 0·2% respectively, but had not yet passed the peak level. The duration of this condition for infectivity in voles infected by nymphal bites was only 1–4 days, whilst infections delivered by adult ticks barely reached the threshold level necessary for successful transmission. When syringe passage was introduced into the parasite maintenance schedule (a) the probability of transmission declined markedly and (b) the time-course of the parasitaemia was altered. If these parameter values are put into a simple model, together with field data on tick and host survival rates, it becomes apparent that additional factors, such as the highly aggregated distribution of ticks on their hosts, must account for the maintenance of B. microti at the levels seen in wild small mammal populations.
Feeding behaviour of tsetse flies (Glossina pallidipes Austen) on Trypanosoma-infected oxen in Kenya
Authors: Baylis M. , Mbwabi A. L. 
Published: June 2009

SUMMARYAn incomplete ring of electric nets was placed around oxen which were either uninfected, infected with Trypanosoma vivax, or infected with T. congolense. The numbers of fed and unfed Glossina pallidipes caught on the nets were used to estimate the attractiveness of the oxen to tsetse, and the feeding success of the tsetse on the oxen. Oxen infected with T. congolense attracted more G. pallidipes than the other groups of oxen. Taking into consideration daily variation in the abundance or activity of the flies, oxen infected with T. congolense were about 70% more attractive to G. pallidipes than were uninfected oxen or oxen infected with T. vivax. The latter two groups mostly attracted high numbers of G. pallidipes on days when the flies were especially abundant or active. The feeding success of G. pallidipes declined with increase in the rate at which oxen made anti-fly movements. Taking this movement rate into consideration, the feeding success of G. pallidipes on oxen infected with T. congolense was approximately 60% greater than on uninfected oxen or oxen infected with T. vivax. It is suggested that vasodilation induced by T. congolense may account for the difference in feeding success. The level of parasitaemia of T. congolense or T. vivax was not found to affect either the attractiveness of oxen or the feeding success on oxen. There was significant daily variation in the mean fat content of male G. pallidipes caught around the oxen but no effect of mean daily fat content on the proportion of males that fed. The mean haematin content of fed male G. pallidipes was positively correlated with the packed cell volume of the ox on which they fed.
Sequence, expression and localization of calmodulin-domain protein kinases inEimeria tenellaandEimeria maxima
Authors: Dunn P. P. J. , Bumstead J. M. , Tomley F. M. 
Published: June 2009

SUMMARYWe have isolated and sequenced cDNA clones fromEimeria tenellaandEimeria maximawhich encode proteins that share homology with a recently described family of calmodulin-domain protein kinases. The primary sequence data show that each of the protein kinases can be divided into 2 main functional domains – an amino-terminal catalytic domain typical of serine/threonine protein kinases and a carboxy-terminal domain homologous to calmodulin, which is capable of binding calcium ions at 4 ‘EF-hand’ motifs. Expression of theE. tenellacalmodulin-domain protein kinase (EtCDPK) increased towards the end of oocyst sporulation, as judged by Northern and Western blotting, and indirect immunofluorescent antibody labelling showed that within a few minutes of adding sporozoites to target host cells inin vitroculture EtCDPK was found to be specifically associated with a filament-like structure that converges at the apical end of the parasite. Once the parasite entered the host cell EtCDPK appeared to be left on the host cell membrane at the point of entry, indicating a brief yet specific role for this molecule in the invasion of host cells byE. tenella.
DNA synthesis in gametocytes of Plasmodium falciparum
Authors: Janse C. J. , Ponnudurai T. , Lensen A. H. W. , Meuwissen J. H. E. Th. , Ramesar J. , Van Der Ploeg M. , Overdulve J. P. 
Published: June 2009

SUMMARYThe DNA content of Plasmodium falciparum gametocytes during intra-erythrocytic development and during gametogenesis was established by cytophotometric methods. Intra-erythrocytic micro- and macrogametocytes (Stage I-Stage VB) contain about twice the amount of DNA of haploid sporozoites and ringstages, indicating that DNA is synthesized during transformation of ringforms into Stage I gametocytes. Microgametocytes, after activation at pH 8, rapidly duplicate their genome several times, while the DNA content of macrogametocytes remains constant during gametogenesis.
Observations on the implications of pathology induced by experimental schistosomiasis in baboons in evaluating the development of resistance to challenge infection
Authors: Sturrock R. F. , Cottrell B. J. , Lucas S. , Reid G. D. F. , Seitz H. M. , Wilson R. A. 
Published: June 2009

SUMMARYLiver samples from 10Schistosomamansoni-infected baboons all yielded eggs but neither their egg counts nor duration of infection (< 226 weeks) correlated with the slightly elevated liver collagen levels or minimal histological fibrosis observed. Approximately 10% of inert 9 and 15 μm diameter microspheres injected into the mesenterio veins of 2 baboons with acute, challengeS. mansoniinfection reached their lungs (mainly 9 μm microspheres). Lung egg recoveries over 1000 were significantly less common among 175 baboons exposed once toS. monsoniinfections than among 56 baboons exposed more than once. Among 221S. mansoni-andS. haematobium-infected baboons, female worm, total tissue egg and lung egg recoveries were significantly correlated with each other but not with liver or (where available) spleen weights. Liver and spleen weights were strongly correlated with total body weight. Baboons did not develop significant liver fibrosis, even after prolonged schistosome infections. However, some liver ‘leakiness’ developed during acute primary and challenge infections, allowing small inert particles and eggs to pass to the lungs, but this ‘leakiness’ was not associated with resistance to challenge. In contrast to mice, such resistance in baboons cannot, therefore, be explained simply in terms of pathological changes due to previous infections.
An association between schistosomes and contrapsin, a mouse serine protease inhibitor (serpin)
Authors: Modha J. , Parikh Vaishu , Gauldie J. , Doenhoff M. J. 
Published: June 2009

SUMMARYAn antigen in homogenates of adultSchistosoma mansoniworms grown in mice, and immunoprecipitated by polyspecific rabbit antiserum, has been identified as contrapsin, a mouse serine protease inhibitor (serpin). In the serum of some mice infected withS. mansonicontrapsin was found with altered immunoelectrophoretic characteristics when compared with contrapsin from uninfected mice.
Analysis of Opisthorchis viverrini antigens by immunoprecipitation and polyacrylamide gel electrophoresis
Authors: Wongratanacheewin S. , Chawengkirttikul R. , Bunnag D. , Sirisinha S. 
Published: June 2009

SUMMARYAntigenicity of adult Opisthorchis viverrini, metacercariae and eggs was investigated by radio-immunoprecipitation and polyacrylamide gel electrophoresis using sera from patients with opisthorchiasis and from hamsters experimentally infected with 0. viverrini metacercariae. 125I-labelled aqueous somatic extract and in vitro metabolic products of adult worms, and the extracts of metacercariae and eggs were immunoprecipitated, electrophoresed and autoradiographed and major antigens were characterized. Although components with Mr of > 116, 89, 78 and 20 kD appeared to be specifically associated with the somatic extract of adult fluke, the 89 kD protein was the most prominent component found in the in vitro culture fluid of adult worms and the metacercarial extract. Hamsters, experimentally infected with 0. viverrini, also showed the presence of antibody reactive with the 89 kD component within 15 days of infection. The potential of this antigen in immunodiagnosis is discussed.
The importance of host age and sex to patterns of reinfection with Ascaris lumbricoides following mass anthelmintic treatment in a South Indian fishing community
Authors: Elkins D. B. , Haswell-Elkins Melissa , Anderson R. M. 
Published: June 2009

SUMMARYAnalysis of egg and worm counts of Ascaris recorded at various intervals following a mass anthelmintic treatment programme in a South Indian fishing community is presented. Three indices of infection in the community are compared, namely the prevalence and intensity of egg output (at 2, 6 and 11 months following treatment) and the number of worms expelled following an 11 month period of reinfection. Detailed examination of these measurements revealed significant associations with patient sex and age. The age-prevalence profile of Ascaris infection changed little over time (except immediately following treatment) with the peak prevalence found in the 5–9 year age group. Although 85% of both males and females harboured Ascaris initially, the prevalence following 11 months reinfection was decreased, due to a significantly lower proportion of males being reinfected. By the 11th month of reinfection, the age-intensity profiles of egg output were similar to those observed at initial treatment in the older age groups (10 years and above) and in male children (< 10 years). However, a dramatic increase in the egg output of female children, greatly exceeding the initial mean, was observed within a 6 month period of reinfection. The intensity of egg output did not accurately reflect the abundance of Ascaris recovered via drug-induced expulsion following an 11 month period of reinfection. Although the egg output attained preintervention levels, the average worm intensity reached only half the initial value. The trends in the sex- and age-intensity profiles were consistent at the two sampling dates and showed similar patterns to the egg output curves. The relevance of the results to helminth control and the monitoring of reinfection is discussed.
The population biology of the parasitic stages of Haemonchus contortus
Authors: Smith Gary 
Published: June 2009

SUMMARYThe population biology of the parasitic phase of the Haemonchus contortus life-cycle is discussed within the context of a mathematical model of those processes which regulate population density. Parasite death is assumed to be attributable to at least three processes: failure of the 3rd-stage larvae (L3) to exsheath following ingestion, failure to become established following exsheathment (immune exclusion), and mortality of 4th- and 5th-stage worms on the mucosal surface. The proportion of worms which avoid immune exclusion is a declining sigmoidal function of the duration of infection, at least under conditions of continual exposure to L3 larvae. Under the same conditions, the death rate of 4th- and 5thstage worms can be modelled as an increasing linear function of the host's experience of 3rd stage larvae. The model provides a good description of the worm burdens observed during the course of a long-term trickle infection experiment even though a priori arguments indicate that it would be an inadequate representation of events in the field.
Plasticity of gp63 gene organization in Leishmania (Viannia) braziliensis and Leishmania (Viannia) peruviana
Authors: Victoir K. , Dujardin J. C. , De Doncker S. , Barker D. C. , Arevalo J. , Hamers R. , Le Ray D. 
Published: June 2009

SUMMARYThe genomic organization of gp63 genes in 4 and 7 isolates of Leishmania braziliensis and L. peruviana, respectively was studied by RFLP analysis with 3 restriction enzymes (Bgl I, Sal I and Apa I). Our results showed a marked polymorphism among isolates. Some characters were specific to L. braziliensis or to L. peruviana, and others specific to the respective biogeographical populations of L. peruviana. The average minimum copy number of gp63 genes was found to be higher in L. braziliensis (71) than in L. peruviana (46), suggesting that deletion of gp63 genes might be partially involved in the size decrease of the chromosome bearing gp63 genes, observed between those 2 species (from 700 to 610 kb). Our results may suggest the existence of at least 2 arrays of heterologous gp63 repeats, varying in relative copy number between L. braziliensis and L. peruviana, and among isolates of the latter species. Rearrangement of the gp63 genes was observed during long-term in vitro maintenance of a reference strain of L. braziliensis. These observations document the existence of a dynamic gp63 gene organization in Leishmania of the braziliensis complex.