bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of a cytosolic aminopeptidase from Encephalitozoon intestinalis
Authors: MILLERSHIP J. J. , CHAPPELL C. L. , OKHUYSEN P. C. , SNOWDEN K. F. 
Published: October 2002

Aminopeptidase activity was detected in Encephalitozoon intestinalis using a fluorometric assay. The aminopeptidase was capable of hydrolysing different amino acids bound to 7-amino-4-trifluoromethyl coumarin, with maximal activity against the amino acid, leucine. Aminopeptidase activity was localized in E. intestinalis spores and in intracellular stages. Enzymatic activity was inhibited by the traditional aminopeptidase inhibitors, bestatin and its analogue, nitrobestatin. Inhibition with the chelating agents, EDTA and 1,10-phenanthroline, suggested that the enzyme activity belongs to the metalloaminopeptidase class. Subcellular fractionation demonstrated that maximal enzyme activity was localized in the cytosolic fraction. Direct fluorogenic substrate analysis by native polyacrylamide gel electrophoresis estimated a molecular weight of 70·8 kDa. Direct fluorogenic analysis by polyacrylamide ampholyte gel electrophoresis indicated an isoelectric point of 4·8. The enzyme was both heat (>37 °C) and cold (<0 °C) labile with an optimal activity at pH 7·2. This is the first report characterizing a cytosolic aminopeptidase in microsporidia.
Characterization and immunolocalization of a main proteinaceous component of the cell wall of the protozoan parasite Perkinsus atlanticus
Authors: MONTES J. F. , DURFORT M. , LLADÓ A. , GARCÍA-VALERO J. 
Published: October 2002

Described in the present study is a major component of the cell wall of 2 of the most pathogenic parasites of molluscs, Perkinsus atlanticus and P. marinus. The component is a high molecular weight protein (233 kDa), which we have named PWP-1 (for Perkinsus wall protein-1). Western blots, using a polyclonal serum generated against purified PWP-1 from P. atlanticus, revealed that this protein is expressed by all walled developmental stages of this protozoon. By means of immunogold electron microscopy, labelling for PWP-1 was strong and specifically associated with the cell wall. The label density and distribution pattern was quite different between trophozoites and prezoosporangia. With regard to the structural organization of this protein, PWP-1 is disulphide-linked to other cell wall components and released from the cell wall only following treatment with a sulphydryl agent. We also report that PWP-1 is a trypsin-resistant protein, both in its native and heat-denatured conformation. In addition, results from the N-terminal microsequence of this protein allow us to define PWP-1 as a novel cell wall protein. Overall, our findings strongly suggest that PWP-1 plays a key role in the organization of the cell wall of these protozoa, promoting their survival.
Impact of protein energy malnutrition on Trichuris suis infection in pigs concomitantly infected with Ascaris suum
Authors: PEDERSEN S. , SAEED I. , MICHAELSEN K. F. , FRIIS H. , MURRELL K. D. 
Published: October 2002

The objective of this experiment was to investigate a possible interaction between protein and energy malnutrition (PEM) and intestinal nematode infections. We report on a 3×2 factorial study in which pigs were fed either a low protein energy (LPE), low protein (LP) or a normal protein energy (NPE) diet, and 6 weeks later inoculated with Trichuris suis (4000 infective eggs). Secondarily, in order to obtain a polyparasitic status, pigs were concomitantly inoculated with Ascaris suum (600 infective eggs). The number of T. suis-infected pigs was higher in LP pigs compared with NPE pigs (100 versus 58%; P = 0·037), although the differences in median T. suis worm burdens between groups at necropsy 10 weeks post-infection (p.i.) (LPE: 795; LP: 835; NPE: 48 worms; P = 0·33) were not significant. Interestingly, only T. suis in NPE were highly aggregated (k = 0·44), in contrast to a more uniform distribution among pigs in LPE (k = 1·43) and LP (k = 1·55) i.e. the majority of pigs harboured moderate worm burdens in LPE and LP, while most pigs had few or no worms in NPE. Further, T. suis worms in the LPE and LP groups were decreased in length (mean: LPE: 23·5 mm; LP: 24·3 mm; NPE: 29·4 mm; P = 0·004). The pre-patency period of T. suis was also extended in the LPE and LP groups, as reflected by lower faecal egg output at week 6 (P = 0·048) and/or 7 p.i. (P = 0·007). More A. suum worms were recovered from LP compared with the NPE group (mean: 5·4 versus 0·6; P = 0·040); this was accompanied by a higher faecal egg output in the former (P = 0·004). The low protein diets resulted in lower pig body weight gains, serum albumin, haemoglobin and packed cell volume (PCV) levels as well as diminished peripheral eosinophil counts. Infection significantly altered these parameters in the low protein groups, i.e. the pathophysiological consequences of infection were more severe in the PEM pigs. These results demonstrate that reduced protein in the diet leads to malnourishment of both the host pigs and T. suis, and compromises the pig's ability to resist infection by T. suis and A. suum.
Detection of changes occurring during recovery from the dauer stage in Heterorhabditis bacteriophora
Authors: DOLAN K. M. , JONES J. T. , BURNELL A. M. 
Published: October 2002

Nematodes of the genus Heterorhabditis are insect parasites that are widely used as biological control agents. When conditions are unfavourable for reproduction in H. bacteriophora, a long-lived, non-feeding, survival and dispersal stage, the dauer juvenile (DJ), is formed. This DJ stage is also adapted for host finding and infection. When it infects a suitable host, the DJ recovers and resumes growth and development. We describe a series of methods for improved detection of recovery in H. bacteriophora. We also describe some of the physiological changes that occur immediately after the onset of recovery in these nematodes as revealed using fluorescent nucleic acid binding SYTO dyes. Although recovery could be monitored using morphological changes, we found that observation of the uptake of fluorescent latex microspheres by recovering nematodes was a far more sensitive and efficient means of detecting recovery. SYTO dyes were also found to be useful indicators of recovery, binding to the pharyngeal glands and genital primordia as little as 3 h after the onset of recovery. The use of SYTO dyes also indicated that the pharyngeal glands produce large quantities of RNA following the onset of recovery, implying that these structures may produce proteins important in the infection and/or feeding process of H. bacteriophora.
A multiplex allele specific polymerase chain reaction (MAS-PCR) on the dihydrofolate reductase gene for the detection of Cryptosporidium parvum genotypes 1 and 2
Authors: GILES M. , WARHURST D. C. , WEBSTER K. A. , WEST D. M. , MARSHALL J. A. 
Published: October 2002

A multiplex allele specific polymerase chain reaction (MAS-PCR) based on the Cryptosporidium parvum dihydrofolate reductase (dhfr) gene sequence differentiates genotype 1 (‘Human’) from 2 (‘Cattle’) in a 1-step reaction. The MAS-PCR was validated on a panel of 34 microscopically positive C. parvum faecal samples of human and animal origin in comparison with 2 published PCR-restriction fragment length polymorphism (RFLP) methods targeting dhfr and the oocyst wall protein (cowp) genes. A validation panel of 37 negative faecal samples of human and animal origin was also tested in comparison with the cowp PCR-RFLP. MAS-PCR was found to be as sensitive for species detection as the most sensitive of the other tests, and detected more mixed genotype infections than the two other tests combined. In addition the MAS-PCR showed equivalent detection sensitivity in comparison with a published nested RFLP targeting the SSU rRNA gene, on a panel of prepared mixed genotype samples. The 1-step reaction is simpler and less expensive to perform than the RFLP methods, while the C. parvum specific amplicons and those for genotypes 1 and 2 (575, 357 and 190 bp respectively) can be easily distinguished on agarose gel.
Kinetics of exsheathment of infective ovine and bovine strongylid larvae in vivo and in vitro
Authors: HERTZBERG H. , HUWYLER U. , KOHLER L. , REHBEIN St , WANNER M. 
Published: October 2002

The aim of the study was to investigate the longitudinal changes of exsheathment of ovine and bovine 3rd-stage strongylid larvae in an artificial rumen (RUSITEC) and to compare the results with in vivo data obtained from rumen-fistulated sheep. Infective larvae were incubated in nylon mesh bags in the sheep rumen or the RUSITEC apparatus for periods of 1, 6 and 12 h, respectively. The 12 h exsheathment rates in the rumen and the RUSITEC apparatus (in parentheses) were as follows: Haemonchus contortus: 100% (100%), Ostertagia circumcincta: 100% (76%), O. leptospicularis: 100% (100%), O. ostertagi: 53% (59%), Trichostrongylus axei: 100% (100%), T. colubriformis: 37% (36%), Cooperia curticei: 94% (76%), C. oncophora: 95% (89%), Nematodirus filicollis: 0% (N.D.), N. spathiger: 11% (15%), N. battus: 7% (5%), Oesophagostomum venulosum: 17% (9%), Chabertia ovina: 7% (2%), Dictyocaulus filaria: 1% (N.D.). Larvae of Nematodirus spp. and T. colubriformis showed a quick rise of the exsheathment rate 2 h after transfer into the abomasum. These results confirm that exsheathment generally occurs in the part of the gastrointestinal tract immediately anterior to the habitat of the adult parasite. The overall similar course of exsheathment in both systems indicates that the essential stimuli for exsheathment were generated and maintained under in vitro conditions of the artificial rumen. In both systems, the bicarbonate concentration and the pH reflected a similar status of the H2CO3/HCO

buffer system, which is known to provide the essential stimuli for larval exsheathment of the abomasal species. These results give evidence that the RUSITEC system represents a valid system for studying the kinetics of exsheathment of strongylid nematodes under in vitro conditions. For 7 of the species investigated the obtained results represent the first data on larval exsheathment in vivo and in vitro.
Properties, stage-dependent expression and localization of Plasmodium falciparum M1 family zinc-aminopeptidase
Authors: ALLARY M. , SCHREVEL J. , FLORENT I. 
Published: October 2002

A Plasmodium falciparum single copy gene predicting a 122 kDa protein belonging to the M1 family of zinc-metallopeptidases was previously reported and related to erythrocytic schizont proteins of 96 (p96) and 68 (p68) kDa. By using protease inhibitors during parasite harvest and enzyme preparations, and polyclonal antibodies specific for 2 peptidic domains deduced from the gene, we identified the 120 kDa precursor and demonstrated its processing into p96 and p68. The N-terminal ends of p96 and p68 were mapped between glycine-123 and lysine-163, both proteins thus containing the catalytic domain. The purified enzyme, here named PfA-M1 (p96/p68), displayed strict aminopeptidase activity, optimal at pH 7·4, with broad substrate spectrum. Its inhibition and reactivation profiles were typical of zinc-metalloaminopeptidases. By Western blotting, PfA-M1 was detected in trophozoites, in addition to schizonts, but not in early rings. PfA-M1 was localized by indirect immunofluorescence confocal microscopy. In trophozoites, the labelling was diffuse in the parasite cytoplasm, with accumulations around the food vacuole. In schizonts, it turned progressively to a vesicle-like pattern, ending as a clear spot in released merozoites. The involvement of PfA-M1 in haemoglobin breakdown and erythrocyte reinvasion is discussed in light of the dual functions recently reported for several P. falciparum proteases.
A review of the population biology and host–parasite interactions of the sea louse Lepeophtheirus salmonis (Copepoda: Caligidae)
Authors: TULLY O. , NOLAN D. T. 
Published: October 2002

Lepeophtheirus salmonis is a specific parasite of salmonids that occurs in the Atlantic and Pacific Oceans. When infestations are heavy fish mortality can occur although the factors that are responsible for causing epizootics, especially in wild salmonid populations are still largely unknown. Over the past 20 years this parasite has caused significant economic losses in farmed salmon production and possibly in wild salmonid populations locally. Understanding the connectivity between populations is crucial to an understanding of the epidemiology of infections and for management of infections in aquaculture. Data from genetics, pesticide resistance, larval dispersal models and spatial and temporal patterns of infestation in wild and farmed hosts suggests a spatially highly structured metapopulation the components of which have different levels of connectivity, probabilities of extinction and influence on the development of local infestations. The population structure is defined mainly by the dispersal dynamics of the planktonic stages and the behaviour of the host.Until recently virtually nothing was known about the relationship between the parasite and the host, or how the host may influence lice at local or population level. Typically, impacts on the host have usually been reported in terms of pathological lesions caused by attachment and feeding of the adult stages, as well as localised mild epithelial responses to juvenile attachment. However many studies report pathology associated with severe infestation. Recent new studies on the host–parasite interactions of L. salmonis have shown that this parasite induces stress-related responses systemically in the host skin and gills and that the stress response and immune systems are modulated. In the second part of this review, these new studies are presented, together with results from other host–parasite model systems where data for caligid sea lice are missing. One of the most revealing methods reported recently is the application of a net confinement stressor to examine modulation of the stress response and immune system of the host fish. This approach has shown that although until now, infective stages of L. salmonis were not thought to affect the host, they do induce systematic effects in the host that result in a stress response and modulated immune system. Host–parasite interactions affecting these stress responses and the immune system may be key factors in facilitating epizootics by reducing the host's ability to reject the parasites, as well as reducing disease resistance under some environmental conditions. The host–parasite interaction therefore needs to be incorporated into any model of population structure and dynamics.
Characterization of Meloidogyne javanica surface coat with antibodies and their effect on nematode behaviour
Authors: SHARON E. , SPIEGEL Y. , SALOMON R. , CURTIS R. H. C. 
Published: October 2002

The surface coat of the 2nd-stage juveniles (J2) of plant-parasitic nematodes is considered to be involved in interactions with microorganisms in the soil and rhizosphere, as well as with the host plant. Characterization of surface antigens might be important in the development of new nematode control strategies. In this study, polyclonal and monoclonal antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes were tested for their binding to the surface coat and secreted–excreted products of M. javanica. Some of the monoclonal and polyclonal antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Western blot analysis of M. javanica surface coat extracts revealed labelling of several polypeptides with a 48 kDa main band for the polyclonal antibody IACR-PC Mi 373, and a 55 kDa main band for PC Mj E2. Further characterization of the antigens recognized by the polyclonal antibody PC Mj E2, in planta, showed that they were present in the parasitic stages J2 and J3 and that the surface coat was shed during root penetration. The hypodermis of the infective juveniles was labelled by PC Mj E2 and the monoclonal antibody IACR-Misec 3F.4, suggesting that these surface antigens are produced in the hypodermis. Nematode behaviour was affected by all the antibodies that bound to the surface coat of the pre-parasitic J2, and we demonstrated that the movement pattern of the M. javanica J2 was affected by these antibodies. Continuous binding of the antibodies to the M. javanica surface inhibited the infection of Arabidopsis thaliana roots on agar plates.
Expression of the filarial nematode phosphorylcholine-containing glycoprotein, ES62, is stage specific
Authors: STEPEK G. , AUCHIE M. , TATE R. , WATSON K. , RUSSELL D. G. , DEVANEY E. , HARNETT W. 
Published: October 2002

ES62, an immunomodulatory phosphorylcholine-containing glycoprotein secreted by the rodent filarial nematode Acanthocheilonema viteae, has previously been shown to be produced by L4 larvae and adult worms only. However, homologous sequences to ES62 have recently been found in L1 and L3 cDNA libraries of certain human filarial nematodes. Therefore, the various stages of A. viteae were re-examined and it was again found that only the post-L3 stages secreted ES62. Synthesis but not secretion by earlier stages was ruled out by examination of the protein content of whole worm extracts and by immunoelectron microscopy. However, examination by PCR of the mRNA for ES62 revealed that it was found in the L1 and L3 larvae. This may explain why homologous sequences to ES62 have been found in Brugia malayi and Onchocerca volvulus larval cDNA libraries. It also suggests that filarial nematodes, in general, may secrete ES62. To obtain evidence for this, we investigated production by Brugia pahangi, a close relation of B. malayi. We found that ES62 was indeed secreted but, as with A. viteae, only by the post-L3 stages, although again the mRNA for ES62 could be detected in the earlier stages. Overall our results suggest that production of ES62 is not species specific, that it is indeed stage specific, and that this may be due to post-transcriptional control of expression.
Potential remedy against Echinococcus multilocularis in wild red foxes using baits with anthelmintic distributed around fox breeding dens in Hokkaido, Japan
Authors: TSUKADA H. , HAMAZAKI K. , GANZORIG S. , IWAKI T. , KONNO K. , LAGAPA J. T. , MATSUO K. , ONO A. , SHIMIZU M. , SAKAI H. , MORISHIMA Y. , NONAKA N. , OKU Y. , KAMIYA M. 
Published: October 2002

The effect of bait-delivered anthelmintic to reduce the prevalence of Echinococcus multilocularis in wild red foxes was evaluated in Koshimizu, in the eastern part of Hokkaido, Japan. The study area (200 km2) was divided into baited and non-baited sections. The anthelmintic baits were distributed around fox den sites in the baited section every month for 13 months. After 1 year of the anthelmintic bait distribution, the prevalence of E. multilocularis in foxes, evaluated either by the parasite egg examination (from 27.1 to 5.6%) or coproantigen ELISA (from 59.6 to 29.7%), decreased in the baited section contrasting to that in the non-baited section (parasite egg: from 18.8 to 24.2%; ELISA: from 41.9 to 45.8%). The prevalence of E. multilocularis in grey red-backed vole Clethrionomys rufocanus, caught around fox dens, born after bait distribution also decreased and was significantly lower than that in non-baited section. However, within the study periods, the coproantigen-positive rate in fox faeces sporadically increased, while egg-positive rate constantly decreased. Since coproantigen ELISA can detect pre-patent infection, this observation indicates that reinfection pressure in the baited section was still high even after the 13 months of anthelmintic bait distribution. Therefore, the bait distribution longer than our study period is required for the efficient control of E. multilocularis in wild red fox population.
Readmission risk in schizophrenia: selection explains previous findings of a progressive course of disorder
Authors: OLESEN A. V. , MORTENSEN P. B. 
Published: October 2002

Background. Several studies have investigated the issue of the natural course of schizophrenia. Our study addressed whether there is evidence for progression, potentially deteriorating, over the long-term course of the disorder.Method. Modern survival analysis techniques were applied to case-register data on the pattern of readmission to in-patient psychiatric facilities. The sample consisted of a total of 8953 persons with schizophrenia.Results. No evidence of a progressive course of schizophrenia was found in the present study. The accelerating pattern of the course of schizophrenia described by some authors, including a previous analysis of an almost identical dataset, can be explained by selection.Conclusions. Heterogeneity reflecting the various levels of individual vulnerability may govern the overall individual course of schizophrenia. We hypothesize that the persistent deficit syndrome and negative symptoms are influential determinants of this heterogeneity.
Major depressive episode among young adults: CIDI-SF versus SCAN consensus diagnoses
Authors: AALTO-SETÄLÄ T. , HAARASILTA L. , MARTTUNEN M. , TUULIO-HENRIKSSON A. , POIKOLAINEN K. , ARO H. , LÖNNQVIST J. 
Published: October 2002

Background. We aimed to evaluate the diagnostic accuracy of a highly structured diagnostic interview in relation to a semi-structured diagnostic procedure. We compared the World Health Organization Composite International Diagnostic Interview Short Form (CIDI-SF) in diagnosing major depressive episode (MDE) to consensus diagnoses based on the SCAN interview (Schedules for Clinical Assessment in Neuropsychiatry).Method. Subjects comprised a follow-up sample of 239 20–24-year-old former high-school students who were administered the SCAN and immediately thereafter the CIDI-SF. Concordance was estimated for 12-month MDE, using different cut-points of the CIDI-SF and for any affective disorders.Results. Correspondence between instruments was moderate for MDE (κ = 0.43, sensitivity 0.71, specificity 0.82), but better for any affective disorder (κ = 0.60, sensitivity 0.70, specificity 0.90). Most false negatives suffered from their depression as much as those correctly identified by the CIDI-SF. False negativity was mainly due to not endorsing the stem questions of the CIDI-SF. Of the false positives almost half had an affective disorder other than MDE.Conclusions. The CIDI-SF seems to function best in identifying a broader category of affective disorders. It could be useful in large-scale community surveys where more extensive psychiatric interviews are not feasible.
Does problem-solving treatment work through resolving problems?
Authors: MYNORS-WALLIS LAURENCE 
Published: October 2002

Background. A randomized controlled trial of problem-solving treatment, antidepressant medication and the combination of the two treatments found no difference in treatment efficacy for major depressive disorders in primary care. In addition to treatment outcome, the trial sought to determine possible mechanisms of action of the problem-solving intervention.Method. Two potential mechanisms of action of problem-solving treatment were evaluated by comparison with drug treatment. First, did problem-solving treatment work by achieving problem resolution and secondly, did problem-solving treatment work by increasing the patients' sense of mastery and self-control?Results. Problem-solving treatment did not achieve a greater resolution in the patients' perception of their problem severity by comparison with drug treatment, neither did problem-solving treatment result in a greater sense of mastery or self-control.Conclusions. The results from this study did not support the hypotheses that for patients with major depression, by comparison with antidepressant medication: problem-solving treatment would result in better problem resolution; or that problem-solving treatment would increase the patients' sense of mastery and self-control.