SEARCH · PubMed Health

Results for “FASCIOLA HEPATICA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources

PubMed2006

Biochemical characterisation of the recombinant peroxiredoxin (FhePrx) of the liver fluke, Fasciola hepatica.

The parasitic helminth Fasciola hepatica secretes a 2-Cys peroxiredoxin (Prx) that may play important functions in host-parasite interaction. Recombinant peroxiredoxin (FhePrx) prevented metal-catalyzed oxidative nicking of plasmid DNA and detoxified hydrogen peroxide when coupled with Escherichia coli thioredoxin and thioredoxin reductase (k(cat)/K(m)=5.2 x 10(5)M(-1)s(-1)). Enzyme kinetic analysis revealed that the catalytic efficiency of FhePrx is similar to other 2-Cys peroxiredoxins; the enzyme displayed saturable enzyme Michaelis-Menten type kinetics with hydrogen peroxide, cumene hydroperoxide and t-butyl hydroperoxide, and is sensitive to concentrations of hydrogen peroxide above 0.5 mM. Like the 2-Cys peroxiredoxins from a related helminth, Schistosoma mansoni, steady-state kinetics indicate that FhePrx exhibits a saturable, single displacement-like reaction mechanism rather than non-saturable double displacement (ping-pong) enzyme substitution mechanism common to other peroxiredoxins. However, unlike the schistosome Prxs, FhePrx could not utilise reducing equivalents supplied by glutathione or glutathione reductase.

Animals↗

PubMed1980

In vitro effect of immune serum and bovine granulocytes on juvenile Fasciola hepatica.

Cattle, infected with Fasciola hepatica metacercariae, produce antibodies against the outer glycocalyx of freshly excysted juvenile F. hepatica. Using 51Cr-release and viability assays such antibodies in the presence or absence of bovine complement did not cause discernible damage to the parasite. The presence of excess antibody caused the build-up of large aggregates of antigen--antibody complexes over the parasite surface; these aggregates were eventually shed into the medium. Neutrophils and eosinophils were obtained by selective stimulation of the mammary gland of heifers, and attached in large numbers to flukes coated with either IgG1 or IgG2. Attachment was dependent on Fc receptors although the adherence of the eosinophils was more prolonged than that of the neutrophils. Using 51Cr-release and viability assays no damage occurred to the flukes using either eosinophils or neutrophils in antibody-dependent cell-mediated cytotoxicity; adherent granulocytes were eventually shed. It is suggested that the rapid turnover and excretion of the outer glycocalyx of juvenile flukes prevents the intimate attachment of granulocytes to the helminth parasite, which is perhaps a prerequisite for cell-mediated damage to occur.

Animals↗

PubMed1989

Isolation and characterization of a cysteine proteinase from Fasciola hepatica adult worms.

Adult Fasciola hepatica worms contain multiple proteinases capable of degrading hemoglobin, immunoglobulins and collagen. Here we report the isolation and biochemical characterization of a cysteine proteinase from acidic extracts of these worms. The enzyme was purified to homogeneity by cation exchange and molecular sieve high-performance liquid chromatography. It eluted at a native molecular weight of approximately 14,500 and migrated as a single band at approximately 14,500 Da upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Activity was assessed by employing synthetic peptide substrates, such as carbobenzoxy-phenylalanyl-arginyl-7-amino-4-trifluoro-methylcoumarin, commonly used to assay other cysteine proteinases. The proteinase was maximally active at pH 6.0, with 50% or more of the activity detected between pH 4.5 and 7.5. Inhibition of activity at pH 5.5 was seen only with compounds known to inhibit cysteine proteinases. No effect was seen with inhibitors of aspartic, serine, or metalloproteinases. The purified enzyme was stable at acidic pH at 4 degrees C, 25 degrees C, -20 degrees C, and in 1 M urea.

Animals↗

PubMed1986

GTP-binding proteins associated with serotonin-activated adenylate cyclase in Fasciola hepatica.

The liver fluke Fasciola hepatica has serotonin (5-hydroxytryptamine) receptors that function through a transmembrane signalling system requiring GTP which activates adenylate cyclase (ATP pyrophosphate-lyase (cyclising), EC 4.6.1.1). Non-hydrolysable GTP analogs and NaF activate adenylate cyclase in membrane particles of these organisms. The nature of GTP-binding proteins in these membranes was studied using bacterial toxins and photoaffinity labelling. Treatment of membrane particles from flukes with cholera toxin increased basal adenylate cyclase activity, but markedly decreased activation by serotonin, non-hydrolysable GTP analogs, and NaF. [32P]ADP-ribosylation by cholera toxin or photoaffinity labelling with [32P]-8-N3GTP identified a 53 kDa protein and a 45 kDa protein which appeared to be similar to the forms of the alpha-subunit of the GTP-binding protein associated with adenylate cyclase in mammals. Treatment of membrane particles by pertussis toxin did not significantly change basal adenylate cyclase activity and did not change the stimulation of cyclase by activators. A 43 kDa protein which was [32P]ADP-ribosylated by either cholera or pertussis toxin, depending on the conditions used, and photoaffinity labelled by [32P]-8-N3GTP may be part of the transmembrane signalling system in the liver flukes.

Adenosine Diphosphate Ribose↗

PubMed1999

Pathological and immunohistochemical study of the liver and hepatic lymph nodes in goats infected with one or more doses of Fasciola hepatica.

Lesions produced by Fasciola hepatica in the liver, gall-bladder and hepatic lymph nodes (HLNs) of four groups of five goats are described; in addition, the distribution of CD3+ T lymphocytes and IgG-lambda light chain-bearing cells was analysed in the hepatic lesions and HLNs. One group of goats received a single oral dose of metacercariae, but the other four groups received four or five doses at different intervals over a period of 11 weeks. Animals that survived were killed 53-55 weeks after the first infective dose. Goats were more susceptible to multiple doses than to a single dose, even when the total number of metacercariae was the same. This greater susceptibility was manifested by the occurrence of deaths and the severity of hepatic lesions. CD3+ lymphocytes were sparse in the infiltrate surrounding the acute migratory tracts, suggesting inhibition of the local cell-mediated immune response. Goats with numerous hepatic calcareous granulomas showed the most severe hepatic damage, including marked cirrhosis, with a striking infiltrate of CD3+ T lymphocytes and lambda IgG- plasma cells, replacing extensive areas of hepatic parenchyma, in which hypertrophy of the smooth endoplasmic reticulum of hepatocytes was evident. These findings were observed mainly in the goats given more than one infective dose.

Animals↗

PubMed2003

Observations on the musculature and isolated muscle fibres of the liver fluke, Fasciola hepatica.

The liver fluke, Fasciola hepatica relies on a well-developed muscular system, not only for attachment, but for many aspects of its biology. Despite this, little is known about the system beyond the gross organization of the main somatic muscle layers. In the present study, a range of techniques have been applied to F. hepatica in order to understand more about various aspects of muscle organization, biochemistry (in terms of muscle proteins) and identity of isolated muscle fibres. Scanning electron microscopy has provided a direct visualization in situ of the somatic muscle layers and the organization of the muscle fibres within the ventral sucker. The muscle bundles contributing to the main somatic muscle layers are made up of up to 10 individual muscle fibres. Phalloidin staining for actin, in conjunction with confocal microscopy, confirmed the presence of 2 main somatic muscle layers (outer circular, inner longitudinal), beneath which lies a third layer of oblique muscle fibres. The use of propidium iodide in combination with phalloidin staining for actin demonstrated that the cell bodies associated with the 2 main somatic muscle layers are situated beneath the longitudinal muscle layer and are connected to their respective muscle fibres by short cytoplasmic processes. Myosin immunoreactivity was demonstrated in the somatic muscle layers and in the muscle layers surrounding various organ systems within the fluke. Double labelling for actin and myosin confirmed the co-localization of the 2 muscle proteins in the muscle fibres of the ventral sucker. Muscle fibres from the somatic muscle layers and the ventral sucker have been isolated and images obtained with phase-contrast microscopy and scanning electron microscopy. The muscle fibres contain actin and myosin, but lack a nucleus, the connection with the cell body having been broken during the isolation procedure.

Actins↗

PubMed1976

Stereoscan studies of eggs, free-swimming and penetrating miracidia and early sporocysts of Fasciola hepatica.

The egg of Fasciola hepatica has a smooth surface with a slightly elevated circle marking the fracture of the operculum. The operculum and the aperture have crenated edges. The epithelial cells of the miracidium are covered with long cilia. When miracidia are vibrated in an ultrasonic cleaner the cilia of the epithelial cells of the four posteroir tiers are broken off only leaving longitudinal rows of cilium stubs, whereas the cilia of the first tier are still retained. The apical papilla is provided with a dorso-ventral furrow, multiciliated pits and isolated sensory cilia. The narrow intercellular ridge is smooth, whereas the epithelial cells have small cytoplasmic knobs between the cilia. The penetration into the snail (Lymnaea truncatula) and the transforamtion into sporocyst may be separated into three phases. (1) Less than 1 min after attachment to the snail the ciliated cells of the anterior tier are shed and swim away. (2) The cilia of the remaining cells beat violently and after about 5 min most cilia are broken off near the cell surface. The miracidium remains for about 15 min embedded as far as the intracellular ridge receptors (lateral papillae and sheathed ciliated nerve endings). During this period extensive contraction and relaxation of the body are performed. (3) The final penetration of the snail epithelium takes about 15 min. Simultaneously with the penetration into the snail tissue the "bald" cells (epithelial cells with cilium stubs only) of the four posterior tiers loosen, florm globules and fall off. The surface below the cells is smooth and in cytoplasmic continuity with the intercellular ridge and the apical papilla, and this syncytium forms the later tegument of the sporocyst. After a few days the tegument of the sporocyst is provided with microvillus-like projections and the apical papilla and sensory structures are lost.

Animals↗

PubMed1992

Detection of stable diagnostic antigen from bile and feces of Fasciola hepatica infected cattle.

Diagnostic antigens in bile and feces from Fasciola hepatica infected cattle were detected and characterized by enzyme-linked immunotransfer blot (EITB) techniques. As sources of antigen, samples of bile, intestinal contents and feces were collected from five uninfected calves and from 10 calves with known Fasciola hepatica burdens. A band detected by EITB using a densitometer in the area corresponding to 26 kDa reacted with rabbit anti-fresh fluke antigen and infected cattle sera but not with fluke-negative rabbit sera, rabbit anti-Fasciola hepatica egg sera, Fascioloides magna positive or negative cattle sera. This band was not detected by Coomassie blue in sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) gels or by Ponceau-S stained nitrocellulose strips. Band groups located at 104-66, 66-42, 42-26 and 25-16 kDa reacted inconsistently with the above sera. Sera from mice hyperimmunized with Fasciola hepatica excretory-secretory (ES) products detected only the 26 kDa band by EITB, without cross-reactivity with bands in the other molecular weight (MW) ranges. The results suggest that the 26 kDa antigen may consist of a stable component of ES products and/or tegument-related worm antigen. Diagnosis of Fasciola hepatica through detection of specific, stable antigens in feces of infected animals offers potential advantages over serum-based tests of better sample accessibility, discrimination between previous and current infections, and possible semi-quantitation of fluke burdens.

Animals↗

PubMed2003

[Cloning and sequencing of cathepsin L1 (FheCL1) gene cDNA of Fasciola hepatica].

OBJECTIVE: To search for a candidate DNA vaccine of Fasciola hepatica. METHODS: Using RT-PCR and digestion with Hind III and BamHI, Fasciola hepatica secreted cathepsin L1 (FheCL1) cDNA was cloned into the expression vector pcDNA3.1. RESULTS: The cloning was successful, the cDNA sequence and its deduced amino acid sequence were analyzed. There was much difference between the cloned FheCL1 and the published one. But the first 20 residues of their amino acid sequences were the same. CONCLUSION: The recombinant plasmid pcDNA3.1-FheCL1 may be a new type of candidate DNA vaccine candidate for Fasciola hepatica. It is possible that Fasciola hepatica presents different sub-species but their amino acid residues (1 to 20) encoded by FheCL1 might build up membrane spanning helix.

Amino Acid Sequence↗

PubMed1997

[Hemorrhagic ascites disclosing massive Fasciola hepatica infection].

Multi-organ infection with Fasciola hepatica is uncommon. We report a case of severe infection with Fasciola hepatica as a cause of liver and peritoneum injuries with hemorrhagic ascites as well as pulmonary, pericardial, splenic and portal system injuries in a 37-year old man who was a native of Green Cape. The patient was in poor general health, had a major inflammatory syndrome, and polyclonal hypergammaglobulinemia (90 g/L). The diagnosis was confirmed by positive distomatosis serology and the presence of eggs of Fasciola hepatica in the histological samples of the liver and peritoneum. After treatment with praziquantel then triclabendazole, the global outcome was favorable.

Adult↗

PubMed1976

Actions of carbon tetrachloride, hexachlorotethane and the products of their metabolism in sheep on Fasciola hepatica.

1 An invitro preparation of Fasciola hepatica is described which responded to electrical stimulation with tetanic spasms. Both carbon tetrachloride (20-500 nl/ml), and its metabolite chloroform (50-1000nl/ml), produced contractions in the preparation which extinguished the responses to electrical stimulation. It is suggested that the spasmogenic action of carbon tetrachloride and its metabolite may contribute to the fasciolifugal action of the drug. 2 Hexachloroethane, another fasiolifuge, had very little effect in the preparation. However, pentachloroethane and tetrachloroethylene, the main products of the metabolism of hexachloroethane in sheep, were potent spasmogens in preparations of Fasciola hepatica. Pentachloroethane was about twice as potent as carbon tetrachloride. 3 Tetrodotoxin (2mug/ml) did not antagonize the responses of the preparation to electrical stimulation of carbon tetrachloride.

Animals↗

PubMed1985

[IgE antibodies in human Fasciola hepatica distomiasis].

In patients infected by Fasciola hepatica, total IgE and specific IgE antibodies have been determined by radioimmunoassays, and IgG, IgA, IgM levels by radial immunodiffusion test (Mancini, 1965). Moreover, total and specific IgE levels have been related to parasite egg burden, age, clinical features and eosinophilia. Elevated total IgE and specific IgE antibodies levels have been found respectively in 76% and 48% of the patients whereas there was no significant variations in other immunoglobulins levels. However, though the amount of total and specific IgE was lower than in other helminthic diseases, it appears to be a significant data of the immune response to parasites as it has been reported and discussed previously. It has been shown a significant relationship between total and specific IgE levels, the number of lines by immunoelectrophoresis, and the results of the indirect haemagglutination and indirect fluorescent antibody techniques; each method appeared to be in equal value to perform the early diagnosis of human Fasciola hepatica. In addition, specific IgE antibodies levels were correlated with eosinophilia specially when it exceeds 15%. This results demonstrate the availability of their measurement in the diagnosis of fascioliasis versus other diseases with marked eosinophilia.

Eosinophilia↗

PubMed1992

Effect of concurrent infection with Muellerius capillaris on the development of redial generations of Fasciola hepatica in Lymnaea truncatula.

The rediae of Fasciola hepatica were counted according to generation in adult and juvenile Lymnaea truncatula following single infection with Fasciola hepatica, double infection with F. hepatica and then Muellerius capillaris, or double infection with M. capillaris and F. hepatica. The rediae found in double infections were essentially first generation and an early cohort from the second generation. The following differences were observed in adult snails which underwent double infection when compared to corresponding single infections: i) dependent rediae were almost completely absent; ii) degenerating independent rediae were found in identical or decreased numbers; iii) living independent rediae of the first generation were decreased in number, while those of the second generation had variable decreased numbers. The results were similar in juvenile snails with double infections, except that the numbers of degenerating independent rediae were higher than those found in corresponding single infections and the numbers of rediae of the second generation were increased. The order of exposure in double infections had no influence on the number and maturation of fasciolid rediae.

Animals↗

PubMed1991

Fasciola hepatica infection in China.

Fasciola hepatica is one of the most common parasites in China that infects ruminants, especially cattle, sheep and goats, and causes considerable morbidity and economic losses in the animal husbandry. The climate in wide areas of China is suitable for the development of F. hepatica and its intermediate snail hosts. However, human infection with the fluke is not common. Up to now, 38 hospital patients and six infected individuals from two epidemiological surveys have been reported in the Chinese literature. F. gigantica infection in herbivorous animals is comparatively rare compared to F. hepatica infections, and only one case was reported in man (Wang, 1984). This paper reviews mainly human infections with F. hepatica in the Chinese literature. Animal infections of the parasite are also briefly described.

Animals↗

PubMed1981

Improved culture of Fasciola hepatica in vitro.

Metacercariae of Fasciola hepatica were excysted in a simple system based on the stimuli determined by Dixon (1966). Reproducibly high levels of excystment (70-80%) were obtained within 3h. Equal volumes of human serum and medium RPMI 1640 with 2% washed human red blood cells supported better growth in vitro than human serum diluted with ELac or NCTC 135. Reduced rates of growth were observed with serum concentrations lower than 50%. During culture over a period of 14 weeks some organisms in every culture grew to a length of 3 mm at a linear rate approximately one quarter of the growth rate in vivo (mouse). A few parasites suddenly began to develop more rapidly after six weeks in culture and reached 6-7 mm in length, comparable to the size of sexually mature Fasciola grown in mice. These cultured worms showed extensive development of the uterus, vitellaria, and testes with spermatozoa. The ovary remained rudimentary and egg formation did not occur.

Animals↗

PubMed1985

Isolation of Fasciola hepatica metacercariae by density gradients.

Fasciola hepatica metacercariae were purified in high yield, removing contaminating cyst walls and plant material by step gradients consisting of 10 ml of 60% Percoll (density = 1.08 g ml-1) and 10 ml of 50% Metrizamide (density = 1.25 g ml-1). Greater than 90% of the metacercariae applied to the density gradients were recovered. These isolated metacercariae had an in vitro excystment rate of greater than 80%, which was the same excystment rate as metacercariae not subjected to density gradient centrifugation.

Animals↗

PubMed1984

Productivity in sheep treated with diamphenethide at different times after infection with Fasciola hepatica.

Sheep with potentially fatal Fasciola hepatica burdens were treated with diamphenethide 4, 8 or 12 weeks after infection. Specific effects of fluke on growth rate and wool growth over and above any anorectic effects were measured by including a pair fed group to each infected group. After drenching, feed intakes returned to that of the uninfected control group. With the exception of sheep drenched in Week 4 after infection, all sheep had significantly lower production after drenching than the control sheep. No compensatory growth was observed and productivity remained depressed for the duration of the trial (26 weeks).

Acetanilides↗

PubMed1996

Immunomodulation of sheep and human lymphocytes by Fasciola hepatica excretory-secretory products.

Fasciola hepatica excretory-secretory (ES) products (30 micrograms ml-1 total ES protein upwards) significantly decreased tritiated thymidine (3HTh) uptake in phytolectin-stimulated sheep lymphocytes. Lower doses of ES products, however, caused an increase in 3HTh uptake in sheep cells stimulated with phytohaemagglutinin (PHA) and Concanavalin A (Con A) and, indeed, ES products were mitogenic on their own. In contrast, 3HTh uptake by human lymphocyte cultures in the presence of phytolectins was progressively inhibited by increasing doses of ES products, and ES products were not mitogenic on their own. The observed inhibitory effects on 3HTh incorporation were not due to toxicity of ES products.

Animals↗