A scanning electron microscope study on the route of entry of triclabendazole into the liver fluke,Fasciola hepatica

Parasitology ◽  
2009 ◽  
Vol 136 (5) ◽  
pp. 523-535 ◽  
Author(s):  
E. TONER ◽  
F. McCONVERY ◽  
G. P. BRENNAN ◽  
M. MEANEY ◽  
I. FAIRWEATHER
Keyword(s):  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Oral Route ◽  
Drug Uptake ◽  
Scanning Electron Microscope Study ◽  
Normal Morphology ◽  
Pharmacological Studies ◽  
Marked Decline ◽  
Scanning Electron

SUMMARYStudies have been carried out to establish the relative importance of oral and trans-tegumental uptake of triclabendazole by the liver fluke,Fasciola hepatica. Experiments were designed to block either oral uptake of drug, by use of ligatures, or trans-tegumental diffusion, by allowing the drug to bind to bovine serum albumin (BSA) in the medium. Changes to the surface morphology of the tegument and gut were assessed by scanning electron microscopy. Flukes were incubatedin vitrofor 24 h in TCBZ.SO at a concentration of 15 μg/ml. Tegumental disruption in ligatured and non-ligatured flukes was similar, suggesting that closing the oral route did not affect drug uptake. The gut remained unaffected by drug treatment. When BSA (30 mg/ml) was present in the medium, there was a marked decline in the level of tegumental disruption. Again, the gut retained a normal morphology. Non-ligatured flukes were also incubated for 24 hin vitroin TCBZ.SO (15 μg/ml) in the presence of red blood cells. Oral ingestion of blood was demonstrated, although the gut surface retained a normal morphology. In contrast, the tegumental surface was severely affected by the drug. The findings support previous pharmacological studies which suggest that trans-tegumental uptake of triclabendazole predominates in the liver fluke.

A transmission electron microscope study on the route of entry of triclabendazole into the liver fluke,Fasciola hepatica

Parasitology ◽  
2009 ◽  
Vol 137 (5) ◽  
pp. 855-870 ◽  
Author(s):  
E. TONER ◽  
G. P. BRENNAN ◽  
F. McCONVERY ◽  
M. MEANEY ◽  
I. FAIRWEATHER
Keyword(s):  
Liver Fluke ◽  
Marked Decrease ◽  
Fasciola Hepatica ◽  
Oral Route ◽  
Drug Uptake ◽  
Oral Uptake ◽  
Transmission Electron ◽  
Pharmacological Studies ◽  
Transmission Electron Microscope Study

SUMMARYUptake of triclabendazole by the liver fluke,Fasciola hepaticahas been studied by experiments designed to block either oral uptake of drug, by use of ligatures, or trans-tegumental diffusion, by allowing the drug to bind to an excess of bovine serum albumin (BSA) in the medium. Changes to the tegumental system, musculature and gut were assessed using transmission electron microscopy. Flukes were incubatedin vitrofor 24 h in TCBZ.SO (15 μg/ml). Disruption to the tegument and muscle was similar in ligatured and non-ligatured flukes, suggesting that closing the oral route did not affect drug uptake. The ultrastructure of the gastrodermal cells remained unchanged. Non-ligatured flukes were also incubated for 24 hin vitroin TCBZ.SO (15 μg/ml) in the presence of red blood cells (RBCs). Oral uptake of blood was demonstrated, but gut ultrastructure remained normal, whereas the tegument was severely disrupted. In separate experiments, ligatured and non-ligatured flukes were incubated in TCBZ.SO (15 μg/ml) in the presence of BSA (30 mg/ml) for 24 hin vitro. There was a marked decrease in the degree of tegumental disruption observed compared with TCBZ.SO action alone; again, the gut remained normal. The findings support previous morphological and pharmacological studies indicating that trans-tegumental uptake of triclabendazole predominates in the liver fluke.

Adult triclabendazole-resistantFasciola hepatica: morphological changes in the tegument and gut followingin vivotreatment with artemether in the rat model

2009 ◽  
Vol 83 (2) ◽  
pp. 151-163 ◽  
Author(s):  
J.F. O'Neill ◽  
R.C. Johnston ◽  
L. Halferty ◽  
G.P. Brennan ◽  
J. Keiser ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Morphological Changes ◽  
Oral Route ◽  
Normal Morphology ◽  
Transmission Electron ◽  
Large Numbers

AbstractA study has been carried out to determine the morphological changes to the adult liver fluke,Fasciola hepaticaafter treatmentin vivowith artemether. Rats were infected with the triclabendazole-resistant Sligo isolate ofF. hepatica, dosed orally with artemether at a concentration of 200 mg/kg and flukes recovered at 24, 48 and 72 h post-treatment (p.t.). Surface changes were monitored by scanning electron microscopy and fine structural changes to the tegument and gut by transmission electron microscopy. Twenty-four hours p.t., the external surface showed minor disruption, in the form of mild swelling of the tegument. The tegumental syncytium and sub-tegumental tissues appeared relatively normal. Forty-eight and seventy-two hours p.t., disruption to the tegumental system increased, with isolated patches of surface blebbing and reduced production of secretory bodies by the tegumental cells being the main changes seen. The gastrodermal cells showed a relatively normal morphology 24 h p.t. By 48 h, large numbers of autophagic vacuoles and lipid droplets were present. Autophagy increased in magnitude by 72 h p.t. and substantial disruption to the granular endoplasmic reticulum was observed. Results from this study show that flukes treatedin vivowith artemether display progressive and time-dependent alterations to the tegument and gut. Disruption to the gut was consistently and substantially more severe than that to the tegument, suggesting that an oral route of uptake for this compound predominates. This is the first study providing ultrastructural information on the effect of an artemisinin compound against liver fluke.

scholarly journals The soluble glutathione transferase superfamily: role of Mu class in triclabendazole sulphoxide challenge in Fasciola hepatica

2021 ◽  
Vol 120 (3) ◽  
pp. 979-991
Author(s):  
Rebekah B. Stuart ◽  
Suzanne Zwaanswijk ◽  
Neil D. MacKintosh ◽  
Boontarikaan Witikornkul ◽  
Peter M. Brophy ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Liver Fluke ◽  
Glutathione Transferase ◽  
Fasciola Hepatica ◽  
Affinity Purification ◽  
Economic Loss ◽  
Differential Abundance ◽  
Parasitic Helminths

AbstractFasciola hepatica (liver fluke), a significant threat to food security, causes global economic loss for the livestock industry and is re-emerging as a foodborne disease of humans. In the absence of vaccines, treatment control is by anthelmintics; with only triclabendazole (TCBZ) currently effective against all stages of F. hepatica in livestock and humans. There is widespread resistance to TCBZ and its detoxification by flukes might contribute to the mechanism. However, there is limited phase I capacity in adult parasitic helminths with the phase II detoxification system dominated by the soluble glutathione transferase (GST) superfamily. Previous proteomic studies have demonstrated that the levels of Mu class GST from pooled F. hepatica parasites respond under TCBZ-sulphoxide (TCBZ-SO) challenge during in vitro culture ex-host. We have extended this finding by exploiting a sub-proteomic lead strategy to measure the change in the total soluble GST profile (GST-ome) of individual TCBZ-susceptible F. hepatica on TCBZ-SO-exposure in vitro culture. TCBZ-SO exposure demonstrated differential abundance of FhGST-Mu29 and FhGST-Mu26 following affinity purification using both GSH and S-hexyl GSH affinity. Furthermore, a low or weak affinity matrix interacting Mu class GST (FhGST-Mu5) has been identified and recombinantly expressed and represents a new low-affinity Mu class GST. Low-affinity GST isoforms within the GST-ome was not restricted to FhGST-Mu5 with a second likely low-affinity sigma class GST (FhGST-S2) uncovered. This study represents the most complete Fasciola GST-ome generated to date and has supported the potential of subproteomic analyses on individual adult flukes.

scholarly journals Transcriptomic analysis reveals a role for the nervous system in regulating growth and development of Fasciola hepatica juveniles

2022 ◽  
Author(s):  
Emily Robb ◽  
Erin McCammick ◽  
Duncan Wells ◽  
Paul McVeigh ◽  
Erica Gardiner ◽  
...  
Keyword(s):  
Nervous System ◽  
Rapid Growth ◽  
Growth And Development ◽  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Expression Profiles ◽  
Neuronal Signalling ◽  
Growth Development

Fasciola spp. liver fluke have significant impacts in veterinary and human medicine. The absence of a vaccine and increasing anthelmintic resistance threaten sustainable control and underscore the need for novel flukicides. Functional genomic approaches underpinned by in vitro culture of juvenile Fasciola hepatica facilitate control target validation in the most pathogenic life stage. Comparative transcriptomics of in vitro and in vivo maintained 21 day old F. hepatica finds that 86% of genes are expressed at similar levels across maintenance treatments suggesting commonality in core biological functioning within these juveniles. Phenotypic comparisons revealed higher cell proliferation and growth rates in the in vivo juveniles compared to their in vitro counterparts. These phenotypic differences were consistent with the upregulation of neoblast-like stem cell and cell-cycle associated genes in in vivo maintained worms. The more rapid growth/development of in vivo juveniles was further evidenced by a switch in cathepsin protease expression profiles, dominated by cathepsin B in in vitro juveniles and then by cathepsin L in in vivo juveniles. Coincident with more rapid growth/development was the marked downregulation of both classical and peptidergic neuronal signalling components in in vivo maintained juveniles, supporting a role for the nervous system in regulating liver fluke growth and development. Differences in the miRNA complements of in vivo and in vitro juveniles identified 31 differentially expressed miRNAs, notably fhe-let-7a-5p , fhe-mir-124-3p and, miRNAs predicted to target Wnt-signalling, supporting a key role for miRNAs in driving the growth/developmental differences in the in vitro and in vivo maintained juvenile liver fluke. Widespread differences in the expression of neuronal genes in juvenile fluke grown in vitro and in vivo expose significant interplay between neuronal signalling and the rate of growth/development, encouraging consideration of neuronal targets in efforts to dysregulate growth/development for parasite control.

scholarly journals A SCANNING ELECTRON MICROSCOPE STUDY OF SURFACE FEATURES OF VIRAL AND SPONTANEOUS TRANSFORMANTS OF MOUSE BALB/3T3 CELLS

1973 ◽  
Vol 59 (3) ◽  
pp. 633-642 ◽  
Author(s):  
Keith R. Porter ◽  
George J. Todaro ◽  
Virginia Fonte
Keyword(s):  
Parent Cell ◽  
Cell Of Origin ◽  
3T3 Cells ◽  
Scanning Electron Microscope Study ◽  
Murine Sarcoma Virus ◽  
Sarcoma Virus ◽  
Surface Morphologies ◽  
Murine Sarcoma ◽  
Scanning Electron

Cells of the mouse line Balb/3T3 as well as three virus-induced transformants and two spontaneous transformants grown in vitro have been studied for their topography by scanning electron microscopy. The parent cell in confluent culture closely resembles an endothelial cell in its form and in the structure of its association with adjacent cells. The tumorigenic transformants produced by SV40, murine sarcoma virus, or polyoma viruses are fusiform to pleomorphic and distinctly different from the cell of origin. They show relatively smooth surfaces except for blebs and marginal microvilli. Perhaps most surprising is the similarity they bear to one another. This is made the more singular by the very different form shown by the tumorigenic transformants of spontaneous origin. One of these, S2-4, possesses a thickened rather than the lamellar form of the parent A31 cell and is covered by long microvilli and many spherical blebs. The other, TuT3, more closely resembles the cell of origin but shows extensive ruffling at its margins. All transformants grow without evidence of contact inhibition. The significance of the surface morphologies and the factors influencing cell form are discussed.

scholarly journals In vitro and in vivo trematode models for chemotherapeutic studies

Parasitology ◽  
2009 ◽  
Vol 137 (3) ◽  
pp. 589-603 ◽  
Author(s):  
J. KEISER
Keyword(s):  
Liver Fluke ◽  
Fasciola Hepatica ◽  
State Of The Art ◽  
Parasitic Diseases ◽  
Current State ◽  
Food Borne ◽  
Essential Components ◽  
Discovery Pipeline

SUMMARYSchistosomiasis and food-borne trematodiases are chronic parasitic diseases affecting millions of people mostly in the developing world. Additional drugs should be developed as only few drugs are available for treatment and drug resistance might emerge. In vitro and in vivo whole parasite screens represent essential components of the trematodicidal drug discovery cascade. This review describes the current state-of-the-art of in vitro and in vivo screening systems of the blood fluke Schistosoma mansoni, the liver fluke Fasciola hepatica and the intestinal fluke Echinostoma caproni. Examples of in vitro and in vivo evaluation of compounds for activity are presented. To boost the discovery pipeline for these diseases there is a need to develop validated, robust high-throughput in vitro systems with simple readouts.

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