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At least 343 records · Page 19Linked to original sources
PubMed1992

Restoration of mitochondrial energy-linked reactions following dexamethasone treatment of rats infected with the liver fluke Fasciola hepatica.

Mitochondria isolated from male Wistar rats experimentally infected with the common liver fluke, Fasciola hepatica, exhibit loss of respiratory control from 2 weeks post-infection (Rule, et al. (1989) Biochem. J. 260, 517-523). We now report that subcutaneous injections of the anti-inflammatory drug, dexamethasone, during the final week of infection prevented the mitochondrial uncoupling and restored respiratory control almost to the levels of uninfected controls. Further investigations have shown that mitochondria from infected rat livers are unable to synthesize ATP and that abnormal respiration is also evident in hepatocytes isolated from infected rats. These abnormalities were absent when infected rats were treated with dexamethasone. In addition, liver mitochondrial function in infected, congenitally athymic, nude rats (CBH/R nu/nu) was not significantly different from that in uninfected nude or Wistar controls. These results provide evidence that the mitochondrial dysfunction in fascioliasis is host-mediated and that T lymphocytes in particular may be involved.

Adenosine Triphosphate↗
PubMed2000

[Natural infestation of Lymnaea truncatula Muller by Fasciola hepatica in the Tozeur oasis in southwest Tunisia].

Natural infestation of Lymnaea truncatula by Fasciola hepatica was studied at various sites in the traditional oasis of Tozeur 8 times between September 1997 and August 1998. Infestation of snails was documented in five of the eight sites with a mean level of 26.1 p. 100. Level of infestation varied depending on the site. It was highest in secondary irrigation canals (32.8 p. 100), seguias, (34.8 p. 100), and secondary drainage canals (34.8 p. 100). Lower levels were observed in the main drainage canal, (15.2 p. 100). Two infestation periods were noted at two sites in relation with spreading of manure by farmers in autumn and spring. Perennial infestation due to the permanent presence of animal hosts was noted at one. Infestation of drainage canals is enhanced by incoming parasite eggs from upstream irrigation canals. Infestation was age dependent reaching up to 100 p. 100 in older snails of 5.5 mm. Environmental factors such as climatic conditions and human intervention are important to sustaining snail infestation in the oasis of Tozeur.

Agriculture↗
PubMed1997

Functional expression of Fasciola hepatica cathepsin L1 in Saccharomyces cerevisiae.

A cDNA encoding the complete precursor of a Fasciola hepatica cathepsin L protease was isolated and sequenced. Functionally active enzyme was expressed and secreted by Saccharomyces cerevisiae transformed with a plasmid carrying the complete gene. Experiments with temperature-sensitive yeast mutants showed that the enzyme is trafficked through the yeast secretory pathway. Yeast transformed with a truncated gene, which lacked the pre-peptide-encoding and most of the pro-peptide-encoding sequences, did not express funtionally active enzyme. The yeast-expressed enzyme exhibited physicochemical properties in common with the native enzyme including, pH optimum for activity, stability at 37 degrees C and ability to cleave gelatin and immunoglobulin. Enzyme kinetic data showed that the native and yeast-expressed cathepsin L1 have similar specificities for substrates with hydrophobic residues in the P2 position. This is the first report of the functional expression of a cathepsin L proteinase in S. cerevisiae that did not require the use of yeast secretory signal sequences.

Animals↗
PubMed2000

[Fecal antigens of Fasciola hepatica potentially useful in the diagnosis of fascioliasis].

This study describes which antigens of Fasciola hepatica are present in the feces of patients with chronic fascioliasis and in the feces of rats infected experimentally with F. hepatica metacercariae. Using a Western blot assay technique with hyperimmune serum obtained from excretory-secretory antigens of adult F. hepatica, we found in the patients' feces antigens of possible diagnostic interest, with molecular weights of 14, 19, 20, 23, 25, 32, 46, 51, and 62 kilodaltons (kDa). In addition, we showed that the peptides of 14, 20, 23, and 51 kDa are also recognized by the majority of the sera from chronic patients. We used affinity chromatography to purify the antigens present in the feces of rats that had been infected for 6 to 12 weeks, using ES78 monoclonal antibody bound to CNBr-activated Sepharose 4B. Through that approach, we identified six polypeptides, of 11, 14, 26, 32, 47, and 51 kDa; three more polypeptides, of 17, 24, and 66 kDa, could only be identified in the feces of rats that had been infected for 10 to 12 weeks. Our results suggest that these polypeptides could be antigens common to both parasitic stages. This is particularly true for the polypeptides of 14, 24, 26, and 51 kDa, because they reacted with the immune sera, the human sera, and the ES78 monoclonal antibody. These polypeptides could be important markers for acute and chronic fascioliasis.

Animals↗
PubMed1976

[The effect of newer anthelmintics on Fasciola hepatica in experimentally infected rats].

The reports deals with the results of testing seven new antihelminthics for Fasciola hepatica in the experimentally invaded Wistar rat. The greatest influence on juvenile flukes (2 and 4 weeks of age) was exerted by diamphenetid (Coriban) applied in a single dose of 100 mg kg-1. Hexachlorophene applied in the dose of 50 mg kg-1 showed the highest effect on sexually mature flukes. All the tested antihelminthics of the halogenated salicylanilide group were ineffective on juvenile stages and only slightly effective on mature F. hepatica flukes. It follows from the results that the effectiveness of some antifasciolics on laboratory animals need not always be in correlation with their effect in ruminants - hence it is necessary to verify the results obtained in laboratory animals and to check them on natural F. hepatica hosts.

Animals↗
PubMed2005

A 6- to 8-day periodicity in cercarial shedding occurred in some Galba truncatula experimentally infected with Fasciola hepatica.

A retrospective study on a total of 669 Galba truncatula (three groups) experimentally infected with Fasciola hepatica was carried out to determine why 6- to 8-day interwave intervals, separating the successive waves of cercarial shedding, occurred with a regular pattern in some snails during the whole patent period. In the three groups of snails, the number of cercariae per shedding wave peaked at the second wave and subsequently decreased up to the fifth wave. The mean length of interwave intervals ranged from 6.8 to 7.8 days and only showed insignificant variations. The number of free cercariae recorded at the end of each interwave interval significantly decreased over the patent period. Similar findings were also noted for intraredial cercariae in the first redial generation and the first cohort of the second generation. By contrast, the number of intraredial cercariae significantly increased along the patent period from the second interwave interval. In the case of each interval separately considered, most numerical variations noted for free cercariae or for intraredial cercariae were insignificant. The periodicity of 6.8-7.8 days found for interwave intervals in the present study might correspond to the infradian-type rhythm already reported for the cercarial shedding of F. hepatica. However, snails showing such regular pattern in cercarial shedding along the patent period were few in number, and one may wonder about the reasons of such snails in the case of F. hepatica.

Animals↗
PubMed2005

The effect of the 5-chloro-2-methylthio-6-(1-naphtyloxy)-1H-benzimidazole on the tegument of immature Fasciola hepatica in their natural host.

The damage to the tegument of 3-week-old Fasciola hepatica was evaluated by scanning electron microscopy (SEM) following treatment with the 5-chloro-2-methylthio-6-(1-naphtyloxy)-1H-benzimidazole (called compound alpha) in its natural host. For the present study, flukes were raised in pelibuey sheep infected orally with metacercariae of F. hepatica; the parasites were recovered from the liver of the sacrificed sheep after 6, 12 and 24 h of treatment with compound alpha. At 6 h of treatment, the flukes showed some lesions on the ventral surface of the anterior region, such as a swollen tegument and blebs. At 12 h after treatment, the specimens showed structural disorganization and spine loss in the ventral anterior region. The tegument of the flukes treated for 24 h was completely lost in some areas of the ventral surface, leaving an exposed basal lamina. The tegument of immature F. hepatica might be a target organ for compound alpha to exert its fasciolicide effect.

Animals↗
PubMed2003

Antioxidant capacity in Fasciola hepatica patients before and after treatment with triclabendazole alone or in combination with ascorbic acid (vitamin C) and tocofersolan (vitamin E).

The aim of the present study was to investigate the effect of triclabendazole (CAS 68786-66-3) therapy alone or in combination with ascorbic acid (vitamin C, CAS 50-81-7) and tocofersolan (vitamin E, CAS 30999-06-5), in Fasciola hepatica patients, on Lipo-peroxidation (LPO) and blood antioxidant capacity. 32 Fasciola hepatica patients were divided into two groups (16 acute and 16 chronic). Each group was divided into two subgroups of 8 patients each. One subgroup was given two consecutive oral doses each of 10 mg/kg body weight of triclabendazole suspension and the other received vitamin C (1000 mg/day) and vitamin E (600 mg/day) for two months, together with the same dose of triclabendazole given to the first subgroup. Ten healthy subjects served as controls. The results revealed a significant increase in serum and erythrocyte lipid peroxide levels and a significant decrease in glutathione levels as well as in glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities in all study groups compared to their corresponding control values. After triclabendazole treatment, pronounced improvements in all studied parameters were observed which could be attributed to the fasciolicidal effect of the drug. The significant improvement of SOD and GPX activities and in lipid peroxide levels after vitamins supplementation as compared to their corresponding values after treatment with triclabendazole alone could be explained on the basis of the potent action of these vitamins in protection against oxidative damage.

Acute Disease↗
PubMed1989

Detection of circulating immune complexes by the enzyme-linked immunosorbent assay in sera from cattle infected with Fasciola hepatica.

Polyethylene glycol-precipitated immune complexes (PIC) from the sera of 5 calves with Fasciola hepatica worm burdens ranging between 27 and 70 flukes were examined for parasite antigen content at 2, 4, 6, 8, 10, and 16 wk postinfection (PI) by the enzyme-linked immunosorbent assay (ELISA). Three assays were devised using an affinity-processed rabbit antibody to worm excretory/secretory (FhES) antigens. The PIC plate assay detected parasite antigen by adherence of anti-FhES antibody to PIC incubated overnight on ELISA plates, and tests were visualized using anti-rabbit peroxidase-linked antibody. The serum complex and PIC capture assay utilized the anti-FhES immunoglobulin as an antigen capture antibody linked to the solid phase. The attached complexes were then detected by the adhering bovine antibody, either soluble complexes in serum or as PIC. All assays showed circulating immune complex (CIC) values elevated at 6-8 wk PI, which generally coincided with increased host circulating antibody to FhES antigens. The greatest detection rate for all of the immune complex (IC) detection assays occurred with the PIC capture assay. It detected antigen in almost 90% of sera tested at 6 and 8 wk PI. Both the serum complex and PIC capture assay detected greatest amounts of CIC in those animals with the largest worm burdens, whereas the PIC plate assay showed no such trend. This study shows that F. hepatica antigen detection in CIC can be used to aid immunologic diagnosis of fascioliasis.

Animals↗
PubMed2005

Phenotypic analysis of adults and eggs of Fasciola hepatica by computer image analysis system.

Knowledge of the morphological phenotypes of the liver fluke Fasciola hepatica (Trematoda: Digenea) is analysed. The influence of parasite age on its dimensions, the adult fluke growth model, variation in a biometric variable versus time, and variation in a biometric variable versus another biometric variable (allometric model) are revised. The most useful allometric model appears to be (y2 m-y2)/y2=c [(y1 m-y1)/y1](b), where y1=body area or body length, y2=one of the measurements analysed, y1 m, y2 m=maximum values towards which y1 and y2, respectively, tend, and c, b=constants. A method based on material standardization, the measurement proposal and allometric analysis is detailed. A computer image analysis system (CIAS), which includes a colour video-camera connected to a stereomicroscope (for adult studies) and a microscope (for egg studies), facilitates the processing of digital imaging. Examples of its application for the analysis of the influence of different factors on the liver fluke phenotype are shown using material from the Northern Bolivian Altiplano, where human and domestic animal fascioliasis is caused by F. hepatica only. Comparisons between the development of livestock fluke populations from highlands and lowlands are discussed and the relationships between host species and liver fluke morphometric patterns is analysed.

Altitude↗
PubMed2000

Vaccination of mice against schistosoma bovis with a recombinant fatty acid binding protein from Fasciola hepatica.

Two strains of mice (NMRI and C57/BL) were each immunized with a 15kDa recombinant Fasciola hepatica fatty acid binding protein (FABP) (Fh15) and challenged percutaneously with Schistosoma bovis cercariae. C57/BL mice immunized with Fh15 had significant reductions in S. bovis worm burden recoveries (72% reductions over controls). When using NMRI mice, Fh15 in Freund's adjuvant failed to induce significant protection against S. bovis. In C57/BL mice, only antibodies to the IgG2a isotype increased after the second immunization and remained high through 8 weeks of S. bovis infection. This is the first time that a heterologous recombinant molecule from F. hepatica has been used in vaccination against S. bovis, obtaining a significant reduction in the number of worms in C57/BL mice.

Animals↗
PubMed2001

Proteomic analysis of Fasciola hepatica excretory-secretory products.

This paper describes a global investigation of the components of Fasciola hepatica excretory-secretory (ES) products by a proteomic approach. Despite the absence of a F. hepatica genome sequencing project we have shown that it was possible to identify 29 of the 60 prominent proteins found using two-dimensional gel electrophoresis. As well as cathepsin L proteases, a number of enzymes implicated in parasite protection from the host immune system were also found to be present in relatively large abundance. These included superoxide dismutase, thioredoxin peroxidase, glutathione S-transferases and fatty acid binding proteins, all of which may play a part in the detoxification of reactive oxygen intermediates. Interestingly, ovine superoxide dismutase was the only protein from the host identified on the gel. We suggest that the relative abundance and protective nature of the components of the ES products of this organism play an important role in its survival within the host. The precise identification, to individual NCBI database entries, of a number of glutathione S-transferases and cathepsin Ls from F. hepatica, by peptide mass fingerprinting, was hampered by multi-database submissions of the two protein superfamilies from this organism.

Amino Acid Sequence↗
PubMed1982

Biosynthesis of A, H, and Lewis blood group determinants in Fasciola hepatica.

Classical methods usually applied in human blood group enzyme assays allowed the detection in Fasciola hepatica of 3-alpha-N-acetyl-D-galactosaminyl-transferase, 2 and 4 alpha-L-fucosyltransferases that correspond to A, H, and Lewis human blood group gene-specified enzymes. Their presence indicates the ability of F. hepatica to synthesize A, H, and Lewis blood group antigens that were recently observed in the liver fluke. The biological significance of the data is discussed in terms of host-parasite relationships.

ABO Blood-Group System↗
PubMed1999

Use of a pre-selected epitope of cathepsin-L1 in a highly specific peptide-based immunoassay for the diagnosis of Fasciola hepatica infections in cattle.

A peptide-based indirect ELISA to detect cattle antibodies against Fasciola hepatica was developed and evaluated for its sensitivity and specificity. An immunogenic antigen released in vitro by F. hepatica was purified. After purification the sequence of the first 20 N-terminal aa of this protein showed considerable homology with cathepsin L-like proteinase. Based on its homology with cathepsin-L1, we further focused on this protein for diagnostic purpose. Predicted B-cell epitopes of cathepsin-L1 were synthesised as single synthetic peptides and tested with respect to their diagnostic potential. An indirect ELISA based on one of these peptides was (i) evaluated further and (ii) compared to the potential of an indirect ELISA with excretion/secretion antigens from adult F. hepatica, or (iii) purified cathepsin-L1. Specificity and sensitivity of the three ELISAs were assessed using sera from calves experimentally infected with pure isolates of Dictyocaulus viviparus, Ostertagia ostertagi, Cooperia oncophora, Nematodirus helvetianus, Schistosoma mattheei, Ascaris suum, Taenia saginata or F. hepatica, respectively, and sera from parasite-naive calves. In addition, sera were analysed from calves naturally infected with F. hepatica. The sensitivities of all three ELISAs were also very high, 98.9% (i), 100% (ii) and 100% (iii). The specificity of the peptide ELISA was very high, 99.8%, whereas specificities of the ES antigens and cathepsin-L1 ELISAs were only 82.8% and 94.6%. In experimentally infected cattle, F. hepatica-specific antibodies were first detected between days 21 and 28 p.i. with all three ELISAs, and the antibody levels persisted in the peptide ELISA until day 183 p.i. All sera from naturally infected calves were positive in the peptide ELISA. These results demonstrate that the peptide-based F. hepatica ELISA is a useful method for detecting antibodies in the sera from cattle infected with F. hepatica. This type of immunodiagnostic will therefore contribute to more accurate diagnosis and to timely curative treatment of animals.

Amino Acid Sequence↗
PubMed2004

Purification, characterization, and immunolocalization of paramyosin from the adult stage of Fasciola hepatica.

Paramyosin, a vaccine candidate in different helminthiases, was purified from the adult liver fluke Fasciola hepatica using two different procedures. The first started with a crude extraction of paramyosin in high-salt buffer followed by gel filtration chromatography and two precipitation-solubilization cycles; in the second, anion exchange chromatography replaced the gel filtration step. In both cases, the apparent molecular weight of the purified protein determined by sodium dodecyl sulfate gel electrophoresis under reducing and non-reducing conditions was 97 kDa and 200 kDa, respectively. The molecular weights were consistent with the presence of a dimeric protein linked by disulfide bridges. Western blot analysis showed that the dimeric and monomeric forms were both recognized by an antiserum raised against the F. hepatica 97 kDa band (alpha-FhPmy), and by an anti- Schistosoma mansoni paramyosin immune serum. Immunohistochemistry using alpha-FhPmy demonstrated the localization of paramyosin within the subtegumental muscle and in muscle cells surrounding the gut of adult parasites. We also observed labeling of extramuscular structures like testes, surface lamellae of the gut and the tegument of adult flukes.

Animals↗