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I Fairweather - One of the best experts on this subject based on the ideXlab platform.
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Surface changes in adult Fasciola hepatica following treatment in vivo with the experimental Fasciolicide, compound alpha
Parasitology Research, 2009Co-Authors: Maeve Mcconville, Robert E. B. Hanna, Gerard P. Brennan, Hillary W. J. Edgar, R Castillo, A Hernández-campos, A. Flanagan, I FairweatherAbstract:Sheep infected with the triclabendazole-susceptible Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks postinfection. Adult flukes were recovered from the bile ducts at 24, 48, and 72 h post-treatment (p.t.). Changes to the surface morphology of the flukes were assessed using scanning electron microscopy (SEM). Flukes were still active at 24 h p.t. and displayed limited areas of disruption, which were restricted to the oral cone region. At 48 h p.t., a reduced level of motility was observed in ~50% of the flukes recovered. Swelling of the tegument was more widespread and was accompanied by blebbing and partial loss of the tegumental covering of the spines. By 72 h p.t., the reduction in motility was greater, and approximately one quarter of the flukes recovered were inactive. In the majority of the flukes examined, the midbody region was marked by a discoloration of the flukes’ tissues. This was seen to be due to the loss of the tegumental syncytium. Sloughing extended into the tail region in some specimens and, in the more badly-affected specimens, the basal lamina was breached to expose the underlying musculature. Elsewhere on the body, the tegument that remained was relatively normal, although areas of swelling and blebbing were present. Overall, the results provided information on the time-scale of changes to the surface morphology of the fluke that underpin the efficacy of compound alpha.
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Immature triclabendazole-resistant Fasciola hepatica: tegumental responses to in vitro treatment with the sulphoxide metabolite of the experimental Fasciolicide compound alpha
Parasitology Research, 2007Co-Authors: M. Mcconville, R Castillo, A Hernández-campos, G. P. Brennan, M. Mccoy, F. Ibarra, I FairweatherAbstract:Juvenile triclabendazole-resistant liver flukes, Fasciola hepatica , were incubated in vitro with 10 μg/ml of the sulphoxide metabolite of the experimental Fasciolicide, compound alpha [5-chloro-2-methylthio-6-(1-naphthyloxy)-1 H -benzimidazole], for 6 and 18 h. Following treatment, the specimens were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tubulin immunocytochemistry. The SEM results revealed a posterior-directed disruption comprised predominantly of swelling and blebbing of the tegument; these changes were more severe and extensive after the longer 18-h incubation. Along with swelling of the tegument and blebbing, the TEM results also revealed swelling of the mitochondria and basal infolds. A decrease in the number of both T1 and T2 secretory bodies was observed in the syncytium and cytoplasmic connections after the 18-h treatment. The circular muscle bundles were also disrupted, in that the organisation of the muscle fibres was irregular and the total number of muscle fibres was reduced. The immunocytochemical studies revealed no significant disruption to the distribution of tubulin immunoreactivity within the tegumental syncytium, the cytoplasmic connections or the associated tegumental cells. The results indicate that alpha.SO is capable of disrupting the tegument of 4-week-old triclabendazole-resistant liver flukes, though the morphological changes were not associated with any significant differences in tubulin immunostaining.
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Fasciola hepatica: effects of the Fasciolicide clorsulon in vitro and in vivo on the tegumental surface, and a comparison of the effects on young- and old-mature flukes
Parasitology Research, 2003Co-Authors: M Meaney, I Fairweather, L S L Mcdowell, G. P. Brennan, A B ForbesAbstract:The ultrastructural changes in Fasciola hepatica induced by the Fasciolicide clorsulon were assessed using scanning electron microscopy. At 8 and 44 weeks post-infection, male Sprague-Dawley rats infected with F. hepatica were dosed orally with clorsulon at a concentration of 12.5 mg/kg and mature flukes recovered from the bile duct after 24 h, 48 h, and 72 h in both experiments. An in vitro incubation was also set up using mature fluke (8 weeks old) incubated with clorsulon for 24 h at a concentration of 10 μg/ml. After 24 h in vivo, the young-mature flukes (8 weeks old) showed significant disruption to the tegumental surface, particularly in the anterior mid-body region, where a distinct band of swelling and blebbing was evident. The band began just behind the ventral sucker and ran posteriorly along both margins. The apical cone region of the fluke was characterised by swelling and blebbing of the surface between the spines. Similar changes were evident after 48 h in vivo, but the disruption was more severe and the mid-body band had spread posteriorly. In approximately half of the specimens recovered after 72 h in vivo, widespread disruption had occurred, with sloughing of the apical membrane or the entire syncytium, over almost all of the oral cone and anterior mid-body. For all time periods, the anterior half of the fluke was more severely affected than the posterior half. No differences were seen between the dorsal and ventral surfaces. Old-mature flukes (44 weeks old) showed regionally similar, but more severe and widespread disruption than that seen in the young-mature flukes. The onset of surface changes occurred more quickly in old-mature flukes as well. Eight-week-old flukes which had been incubated for 24 h in vitro showed surprisingly little disruption, but this may be due to the method by which the drug is taken up by the fluke.
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Fasciola hepatica: tegumental surface alterations following treatment in vivo and in vitro with nitroxynil (Trodax)
Parasitology Research, 2003Co-Authors: B. Mckinstry, I Fairweather, G. P. Brennan, A B ForbesAbstract:Male Sprague-Dawley rats were dosed orally with nitroxynil at a concentration of 40 mg/kg and adult Fasciola hepatica recovered after 24 h, 48 h and 72 h. Surface changes to the flukes were monitored by means of SEM. After the 24 h treatment, extensive swelling and blebbing of the tegument was observed on both surfaces, although the dorsal anterior region was more severely affected than either the posterior dorsal region or entire ventral surface. At high magnification, microvillus-like projections were evident, giving the surface a roughened appearance. After 48 h, the changes evident at 24 h had become more severe and some tegumental loss had occurred in the oral region of the fluke. Surface disruption was particularly evident along the lateral margins of the fluke in this region. In some specimens a single large swelling was present in the dorsal midbody region. The swelling was a more typical feature of flukes recovered. After 72 h, tegumental loss was more widespread, occurring over the oral cone and anterior midbody on the dorsal surface. Overall the dorsal surface was consistently more severely affected than the ventral surface, and the anterior region of the fluke was more disrupted than the posterior region. After 24 h in vitro incubation, the oral cone and midbody exhibited considerable spine loss and swelling. Overall, the dorsal surface was more disrupted than the ventral surface and the anterior region of the fluke was more disrupted than the posterior region. Regional differences in the response of the fluke to nitroxynil will be compared to previously published data with other Fasciolicides. The results indicate that the tegument is an important target for nitroxynil action. Disruption of this, the fluke's main line of defence, would allow the drug access to other internal tissues, leading to more widespread damage.
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Fasciola gigantica: tegumental surface alterations following treatment in vitro with the sulphoxide metabolite of triclabendazole
Parasitology Research, 2002Co-Authors: M Meaney, I Fairweather, G. Brennan, P. Ramasamy, P. SubramanianAbstract:The effect of the active sulphoxide metabolite of the Fasciolicide triclabendazole on the surface morphology of the tropical liver fluke, Fasciola gigantica , was determined in vitro by scanning electron microscopy. At a concentration of 10 µg/ml, swelling and blebbing of the tegument was evident after only 6 h incubation. The blebbing was focussed on the spines. With progressively longer incubation periods, blebbing on the spines became more severe, leading to tegumental sloughing and spine loss. Tegumental loss became more widespread and, after incubation periods of 18 h and 24 h in vitro, perforations of the basal lamina were evident and, in some cases, holes penetrated through the entire fluke in the tail region. The ventral surface was consistently more severely affected than the dorsal and similarly the posterior region of the fluke was more disrupted than the anterior region. The results confirm the potent activity of triclabendazole against F. gigantica .
Ian Fairweather - One of the best experts on this subject based on the ideXlab platform.
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Binding of serum albumin to the anthelmintic drugs albendazole, triclabendazole and their sulphoxides.
Veterinary parasitology, 2010Co-Authors: Emma Chambers, Ian Fairweather, Elizabeth M Hoey, Alan Trudgett, David J TimsonAbstract:The binding of drugs to plasma proteins--especially serum albumin--is an important factor in controlling the availability and distribution of these drugs. In this study we have investigated the binding of two drugs commonly used to treat liver fluke infections, albendazole (ABZ) and triclabendazole (TCBZ), and their sulphoxide metabolites to bovine serum albumin (BSA). Both ABZ and TCBZ caused shifts in the mobility of BSA in native gel electrophoresis. No such changes were observed with the sulphoxides under identical conditions. The drugs, and their sulphoxides, caused quenching of the intrinsic tryptophan fluorescence of BSA, indicating association between the drugs and this protein. Quantification of this quenching suggested a 5-10-fold reduction in affinity of the sulphoxides compared to the parent compounds. These results are discussed in respect to previous work on the pharmacodynamics of these Fasciolicides and will inform the design of novel anthelmintics.
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Fasciola hepatica: disruption of spermatogenesis by the Fasciolicide compound alpha
Parasitology Research, 2009Co-Authors: Maeve Mcconville, Rafael Castillo, Alicia Hernández-campos, Robert E. B. Hanna, Gerard P. Brennan, Maurice Mccoy, Hillary W. J. Edgar, Shirley Mcconnell, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks post-infection. Adult flukes were recovered from the bile ducts at 24, 48, and 72 h post-treatment (p.t.). Changes to the spermatogenic cells in the testis were examined by histology and transmission electron microscopy. Disruption to the testes became increasingly severe over time. The testis tubules shrank in size, became vacuolated, and contained fewer cells. Identification of cell types became difficult, and apoptotic eosinophilic bodies were the predominant feature at 72 h p.t. Changes to the spermatogonia were evident at 24 h p.t., the cells containing swollen and electron-lucent mitochondria. The proportion of tertiary spermatogonia increased at 48 h p.t., and they showed signs of autophagy. Multinucleate spermatogonia were a feature of drug treatment at this time point, and they contained autophagic vacuoles. By 72 h p.t., it was difficult to identify primary and secondary spermatogonia, and there were no recognisable clusters of tertiary spermatogonia. Most spermatogonial cells were multinucleate and in the process of breaking down. With regard to the primary spermatocytes, fragmentation of the cytophore was observed at 24 h p.t. Intact rosettes were rare after 48 h treatment; collections of cells were seen, but were not organised into clusters. By 72 h p.t., no spermatocyte cells could be recognised. The results indicate that spermatogenesis was severely affected by compound alpha.
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Surface changes in adult Fasciola hepatica following treatment in vivo with the experimental Fasciolicide, compound alpha
Parasitology research, 2009Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, R.e.b. Hanna, H.w.j. Edgar, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks postinfection. Adult flukes were recovered from the bile ducts at 24, 48, and 72 h post-treatment (p.t.). Changes to the surface morphology of the flukes were assessed using scanning electron microscopy (SEM). Flukes were still active at 24 h p.t. and displayed limited areas of disruption, which were restricted to the oral cone region. At 48 h p.t., a reduced level of motility was observed in approximately 50% of the flukes recovered. Swelling of the tegument was more widespread and was accompanied by blebbing and partial loss of the tegumental covering of the spines. By 72 h p.t., the reduction in motility was greater, and approximately one quarter of the flukes recovered were inactive. In the majority of the flukes examined, the midbody region was marked by a discoloration of the flukes' tissues. This was seen to be due to the loss of the tegumental syncytium. Sloughing extended into the tail region in some specimens and, in the more badly-affected specimens, the basal lamina was breached to expose the underlying musculature. Elsewhere on the body, the tegument that remained was relatively normal, although areas of swelling and blebbing were present. Overall, the results provided information on the time-scale of changes to the surface morphology of the fluke that underpin the efficacy of compound alpha.
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Ultrastructural changes to the tegumental system and the gastrodermal cells in adult Fasciola hepatica following in vivo treatment with the experimental Fasciolicide, compound alpha.
Parasitology, 2009Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, H.w.j. Edgar, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible, Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks post-infection. Adult flukes were recovered from the bile ducts at 24, 48 and 72 h post-treatment (p.t.). Ultrastructural changes to the flukes were assessed using transmission electron microscopy (TEM), with a view to gathering information on the mechanism(s) of action for compound alpha and on the possible route of its entry into F. hepatica. The tegumental syncytium was more severely affected than the gut at all time-points p.t. with compound alpha, suggesting a predominantly trans-tegumental route of uptake. Disruption to the tegumental system became increasingly severe over time. A stress response was observed at 24 h p.t. and took the form of blebbing and increases in the production and transport of secretory bodies. By 72 h p.t., extensive tegumental loss and degeneration of the tegumental cell bodies had occurred. Degeneration of subtegumental tissues and internal flooding were also observed. Changes in the gastrodermal cells were slow to develop: reduced secretory activity was evident at 72 h p.t.. There was progressive disruption to the somatic muscle layers, with disorganization of the muscle blocks and loss of muscle fibres.
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Surface and internal tegumental changes in juvenile Fasciola hepatica following treatment in vivo with the experimental Fasciolicide, compound alpha
Veterinary Parasitology, 2008Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, H.w.j. Edgar, M. Mccoy, Ian FairweatherAbstract:Abstract Eight indoor-reared, crossbred sheep with no pre-exposure to Fasciola hepatica were infected, by oral gavage, with 200 metacercarial cysts of the triclabendazole-susceptible, Cullompton isolate of F. hepatica. Anthelmintic dosing occurred at 4 weeks post-infection using 15 mg/kg compound alpha. Two treated sheep per time period were euthanized at 24 h, 48 h and 72 h post-treatment with compound alpha. The two sheep from the control group were euthanized alongside the 24 h alpha-treated sheep. Juvenile flukes were recovered from each of the sheeps’ liver and processed for examination by electron microscopy. The surface morphology of the flukes’ tegument was assessed using scanning electron microscopy (SEM). The ultrastructure of the tegumental syncytium and underlying tegumental cells and connections and somatic musculature were investigated using transmission electron microscopy (TEM). Both the SEM and TEM results revealed a level of disruption that increased with time, culminating at 72 h with extensive tegumental loss and substantial degeneration of the cell bodies. The effects of compound alpha on the surface morphology were not particularly apparent until 48 h post-treatment, when disruption included swelling and blebbing of the tegument. At 72 h post-treatment, SEM revealed loss of the entire syncytial layer over large areas of the flukes. In the areas where the syncytium was lost and the basal lamina exposed, lesions of varying sizes had developed, revealing underlying tissues. Though minor forms of disruption to the ultrastructure of the syncytium were observed using TEM 24 h post-treatment, it was at 48 h post-treatment that substantial stress responses occurred. They included the presence of autophagic vacuoles and ‘open’ bodies at the apex of the syncytium and swelling of the basal infolds. The mitochondria within the syncytium and tegumental cells became progressively more disrupted over the three time periods and, by 72 h post-treatment, they were frequently distorted and swollen in appearance, and contained severely swollen cristae. By 72 h, the number of secretory bodies, particularly T1 bodies, had become significantly depleted in their respective cell bodies, cytoplasmic processes and in the tegumental syncytium. Both the circular and longitudinal muscle bundles were severely disrupted 72 h post-treatment. They frequently contained a reduced number of muscle fibres and, in more severe instances, there was an absence of fibres altogether.
Rafael Castillo - One of the best experts on this subject based on the ideXlab platform.
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Efficiency comparison of experimental fosfatriclaben with three commercial Fasciolicides in experimentally infected sheep
Parasitology Research, 2020Co-Authors: Rosa Arias-garcía, Yolanda Vera-montenegro, Miguel Flores-ramos, Rafael Castillo, Alicia Hernández-campos, Froylán Ibarra-velardeAbstract:In this work, we compare and evaluate the efficiency of fosfatriclaben with three commercial Fasciolicides in experimentally infected sheep. Fosfatriclaben is a novel prodrug derived from triclabendazole; it is highly water-soluble with excellent aqueous stability at pH 7, properties that make it ideal for developing intramuscular pharmaceutical compositions in the form of solutions. In order to compare, 30 mixed breed sheep, previously diagnosed negative to fluke eggs, were infected with 200 metacercariae of Fasciola hepatica , twice. Five groups of six animals/each were formed for treatments. Group 1 (G1) was treated with closantel 5% injectable at 5 mg/kg subcutaneously, G2 with clorsulon at 2 mg/kg subcutaneously, G3 with triclabendazole at 12 mg/kg per os, G4 with fosfatriclaben at 6 mg/kg intramuscularly (dose equivalent to triclabendazole content), and G5 remained as the non-treated control. On day 110, fecal samples were examined to determine the percentage of egg reduction after treatment, and sheep were humanely euthanized. The livers were collected, the flukes were extracted, measured, and counted. Efficiency in egg reduction was of 86.8, 90.5, 98.4, and 97.3% for closantel, clorsulon, triclabendazole, and fosfatriclaben, respectively, and efficiency against flukes was of 96.2, 91.9, 99.4, and 95.7%, respectively. No statistical differences were found between treatments. It is concluded that fosfatriclaben at 6 mg/kg intramuscularly presented a high Fasciolicide efficiency, similar to the best commercial Fasciolicides, having advantage over its predecessor since it uses half of the dose required by triclabendazole to remove flukes in sheep under study.
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Assessment of the effective dose of an experimental intramuscular formulation against immature and adult Fasciola hepatica in sheep
Veterinary parasitology, 2018Co-Authors: Froylán Ibarra-velarde, Yolanda Vera-montenegro, Miguel Flores-ramos, Alicia Hernández-campos, Germinal Jorge Cantó-alarcón, Yazmin Alcala-canto, Rafael CastilloAbstract:The effective dose of an injectable prodrug, named compound alpha prodrug, against immature and adult Fasciola hepatica in experimentally infected sheep was determined. In a first experiment, 30 sheep were infected with Fasciola hepatica on day 0 and 50. After microscopic detection of faecal eggs on day 80, groups (n = 6) 1 to 3 were treated with 6, 8 and 10 mg/kg of the experimental water-soluble prodrug compound alpha intramuscularly, respectively. Group 4 was treated with closantel and group 5 remained untreated. Copromicroscopical examinations were made on day 0, 80 and 108. On day 110, trematodes were collected from the bile ducts. Fasciolicide efficacy was assessed as a percentage of fluke-egg and adult-fluke reduction. Fluke length was also recorded. In a second experiment aimed to assess the Fasciolicide activity of compound alpha prodrug against four-week-old flukes, 12 sheep were infected on day 0 and allocated into two groups (n = 6). On day 50 post infection, group A was treated with the experimental water-soluble prodrug compound alpha at 6 mg/kg/IM and B remained untreated. Fasciolicide activity was assessed on day 80 after collection, microscopic observation and measurement of flukes present in the parenchyma for immature stages and on day 108 for adults. Egg output decreased 91.2, 96.0, 98.8 and 94.9% for groups 1, 2, 3 and 4, respectively. Compound alpha prodrug cleared 97.6%, 98.51% and 100% of adult stages in a dose-dependent manner. Closantel killed 81.95% flukes. Regarding the second experiment, 81.2% efficacy was achieved. Immature flukes were significantly smaller in the treated group. It is concluded that the intramuscular application of compound alpha prodrug exerted Fasciolicide efficacy against adults of Fasciola hepatica.
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Fasciola hepatica: disruption of spermatogenesis by the Fasciolicide compound alpha
Parasitology Research, 2009Co-Authors: Maeve Mcconville, Rafael Castillo, Alicia Hernández-campos, Robert E. B. Hanna, Gerard P. Brennan, Maurice Mccoy, Hillary W. J. Edgar, Shirley Mcconnell, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks post-infection. Adult flukes were recovered from the bile ducts at 24, 48, and 72 h post-treatment (p.t.). Changes to the spermatogenic cells in the testis were examined by histology and transmission electron microscopy. Disruption to the testes became increasingly severe over time. The testis tubules shrank in size, became vacuolated, and contained fewer cells. Identification of cell types became difficult, and apoptotic eosinophilic bodies were the predominant feature at 72 h p.t. Changes to the spermatogonia were evident at 24 h p.t., the cells containing swollen and electron-lucent mitochondria. The proportion of tertiary spermatogonia increased at 48 h p.t., and they showed signs of autophagy. Multinucleate spermatogonia were a feature of drug treatment at this time point, and they contained autophagic vacuoles. By 72 h p.t., it was difficult to identify primary and secondary spermatogonia, and there were no recognisable clusters of tertiary spermatogonia. Most spermatogonial cells were multinucleate and in the process of breaking down. With regard to the primary spermatocytes, fragmentation of the cytophore was observed at 24 h p.t. Intact rosettes were rare after 48 h treatment; collections of cells were seen, but were not organised into clusters. By 72 h p.t., no spermatocyte cells could be recognised. The results indicate that spermatogenesis was severely affected by compound alpha.
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Surface changes in adult Fasciola hepatica following treatment in vivo with the experimental Fasciolicide, compound alpha
Parasitology research, 2009Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, R.e.b. Hanna, H.w.j. Edgar, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks postinfection. Adult flukes were recovered from the bile ducts at 24, 48, and 72 h post-treatment (p.t.). Changes to the surface morphology of the flukes were assessed using scanning electron microscopy (SEM). Flukes were still active at 24 h p.t. and displayed limited areas of disruption, which were restricted to the oral cone region. At 48 h p.t., a reduced level of motility was observed in approximately 50% of the flukes recovered. Swelling of the tegument was more widespread and was accompanied by blebbing and partial loss of the tegumental covering of the spines. By 72 h p.t., the reduction in motility was greater, and approximately one quarter of the flukes recovered were inactive. In the majority of the flukes examined, the midbody region was marked by a discoloration of the flukes' tissues. This was seen to be due to the loss of the tegumental syncytium. Sloughing extended into the tail region in some specimens and, in the more badly-affected specimens, the basal lamina was breached to expose the underlying musculature. Elsewhere on the body, the tegument that remained was relatively normal, although areas of swelling and blebbing were present. Overall, the results provided information on the time-scale of changes to the surface morphology of the fluke that underpin the efficacy of compound alpha.
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Ultrastructural changes to the tegumental system and the gastrodermal cells in adult Fasciola hepatica following in vivo treatment with the experimental Fasciolicide, compound alpha.
Parasitology, 2009Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, H.w.j. Edgar, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible, Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks post-infection. Adult flukes were recovered from the bile ducts at 24, 48 and 72 h post-treatment (p.t.). Ultrastructural changes to the flukes were assessed using transmission electron microscopy (TEM), with a view to gathering information on the mechanism(s) of action for compound alpha and on the possible route of its entry into F. hepatica. The tegumental syncytium was more severely affected than the gut at all time-points p.t. with compound alpha, suggesting a predominantly trans-tegumental route of uptake. Disruption to the tegumental system became increasingly severe over time. A stress response was observed at 24 h p.t. and took the form of blebbing and increases in the production and transport of secretory bodies. By 72 h p.t., extensive tegumental loss and degeneration of the tegumental cell bodies had occurred. Degeneration of subtegumental tissues and internal flooding were also observed. Changes in the gastrodermal cells were slow to develop: reduced secretory activity was evident at 72 h p.t.. There was progressive disruption to the somatic muscle layers, with disorganization of the muscle blocks and loss of muscle fibres.
M. Mcconville - One of the best experts on this subject based on the ideXlab platform.
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Surface changes in adult Fasciola hepatica following treatment in vivo with the experimental Fasciolicide, compound alpha
Parasitology research, 2009Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, R.e.b. Hanna, H.w.j. Edgar, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks postinfection. Adult flukes were recovered from the bile ducts at 24, 48, and 72 h post-treatment (p.t.). Changes to the surface morphology of the flukes were assessed using scanning electron microscopy (SEM). Flukes were still active at 24 h p.t. and displayed limited areas of disruption, which were restricted to the oral cone region. At 48 h p.t., a reduced level of motility was observed in approximately 50% of the flukes recovered. Swelling of the tegument was more widespread and was accompanied by blebbing and partial loss of the tegumental covering of the spines. By 72 h p.t., the reduction in motility was greater, and approximately one quarter of the flukes recovered were inactive. In the majority of the flukes examined, the midbody region was marked by a discoloration of the flukes' tissues. This was seen to be due to the loss of the tegumental syncytium. Sloughing extended into the tail region in some specimens and, in the more badly-affected specimens, the basal lamina was breached to expose the underlying musculature. Elsewhere on the body, the tegument that remained was relatively normal, although areas of swelling and blebbing were present. Overall, the results provided information on the time-scale of changes to the surface morphology of the fluke that underpin the efficacy of compound alpha.
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Ultrastructural changes to the tegumental system and the gastrodermal cells in adult Fasciola hepatica following in vivo treatment with the experimental Fasciolicide, compound alpha.
Parasitology, 2009Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, H.w.j. Edgar, Ian FairweatherAbstract:Sheep infected with the triclabendazole-susceptible, Cullompton isolate of Fasciola hepatica were dosed with 15 mg/kg of compound alpha at 12 weeks post-infection. Adult flukes were recovered from the bile ducts at 24, 48 and 72 h post-treatment (p.t.). Ultrastructural changes to the flukes were assessed using transmission electron microscopy (TEM), with a view to gathering information on the mechanism(s) of action for compound alpha and on the possible route of its entry into F. hepatica. The tegumental syncytium was more severely affected than the gut at all time-points p.t. with compound alpha, suggesting a predominantly trans-tegumental route of uptake. Disruption to the tegumental system became increasingly severe over time. A stress response was observed at 24 h p.t. and took the form of blebbing and increases in the production and transport of secretory bodies. By 72 h p.t., extensive tegumental loss and degeneration of the tegumental cell bodies had occurred. Degeneration of subtegumental tissues and internal flooding were also observed. Changes in the gastrodermal cells were slow to develop: reduced secretory activity was evident at 72 h p.t.. There was progressive disruption to the somatic muscle layers, with disorganization of the muscle blocks and loss of muscle fibres.
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Surface and internal tegumental changes in juvenile Fasciola hepatica following treatment in vivo with the experimental Fasciolicide, compound alpha
Veterinary Parasitology, 2008Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, Gerard Brennan, A. Flanagan, H.w.j. Edgar, M. Mccoy, Ian FairweatherAbstract:Abstract Eight indoor-reared, crossbred sheep with no pre-exposure to Fasciola hepatica were infected, by oral gavage, with 200 metacercarial cysts of the triclabendazole-susceptible, Cullompton isolate of F. hepatica. Anthelmintic dosing occurred at 4 weeks post-infection using 15 mg/kg compound alpha. Two treated sheep per time period were euthanized at 24 h, 48 h and 72 h post-treatment with compound alpha. The two sheep from the control group were euthanized alongside the 24 h alpha-treated sheep. Juvenile flukes were recovered from each of the sheeps’ liver and processed for examination by electron microscopy. The surface morphology of the flukes’ tegument was assessed using scanning electron microscopy (SEM). The ultrastructure of the tegumental syncytium and underlying tegumental cells and connections and somatic musculature were investigated using transmission electron microscopy (TEM). Both the SEM and TEM results revealed a level of disruption that increased with time, culminating at 72 h with extensive tegumental loss and substantial degeneration of the cell bodies. The effects of compound alpha on the surface morphology were not particularly apparent until 48 h post-treatment, when disruption included swelling and blebbing of the tegument. At 72 h post-treatment, SEM revealed loss of the entire syncytial layer over large areas of the flukes. In the areas where the syncytium was lost and the basal lamina exposed, lesions of varying sizes had developed, revealing underlying tissues. Though minor forms of disruption to the ultrastructure of the syncytium were observed using TEM 24 h post-treatment, it was at 48 h post-treatment that substantial stress responses occurred. They included the presence of autophagic vacuoles and ‘open’ bodies at the apex of the syncytium and swelling of the basal infolds. The mitochondria within the syncytium and tegumental cells became progressively more disrupted over the three time periods and, by 72 h post-treatment, they were frequently distorted and swollen in appearance, and contained severely swollen cristae. By 72 h, the number of secretory bodies, particularly T1 bodies, had become significantly depleted in their respective cell bodies, cytoplasmic processes and in the tegumental syncytium. Both the circular and longitudinal muscle bundles were severely disrupted 72 h post-treatment. They frequently contained a reduced number of muscle fibres and, in more severe instances, there was an absence of fibres altogether.
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Immature triclabendazole-resistant Fasciola hepatica: tegumental responses to in vitro treatment with the sulphoxide metabolite of the experimental Fasciolicide compound alpha
Parasitology Research, 2007Co-Authors: M. Mcconville, R Castillo, A Hernández-campos, G. P. Brennan, M. Mccoy, F. Ibarra, I FairweatherAbstract:Juvenile triclabendazole-resistant liver flukes, Fasciola hepatica , were incubated in vitro with 10 μg/ml of the sulphoxide metabolite of the experimental Fasciolicide, compound alpha [5-chloro-2-methylthio-6-(1-naphthyloxy)-1 H -benzimidazole], for 6 and 18 h. Following treatment, the specimens were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tubulin immunocytochemistry. The SEM results revealed a posterior-directed disruption comprised predominantly of swelling and blebbing of the tegument; these changes were more severe and extensive after the longer 18-h incubation. Along with swelling of the tegument and blebbing, the TEM results also revealed swelling of the mitochondria and basal infolds. A decrease in the number of both T1 and T2 secretory bodies was observed in the syncytium and cytoplasmic connections after the 18-h treatment. The circular muscle bundles were also disrupted, in that the organisation of the muscle fibres was irregular and the total number of muscle fibres was reduced. The immunocytochemical studies revealed no significant disruption to the distribution of tubulin immunoreactivity within the tegumental syncytium, the cytoplasmic connections or the associated tegumental cells. The results indicate that alpha.SO is capable of disrupting the tegument of 4-week-old triclabendazole-resistant liver flukes, though the morphological changes were not associated with any significant differences in tubulin immunostaining.
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Adult triclabendazole-resistant Fasciola hepatica: surface and subsurface tegumental responses to in vitro treatment with the sulphoxide metabolite of the experimental Fasciolicide compound alpha.
Parasitology, 2006Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, G. P. Brennan, M. Mccoy, F. Ibarra, Ian FairweatherAbstract:Mature Fasciola hepatica of the triclabendazole-resistant Sligo isolate were incubated in vitro with 10 microg/ml of the sulphoxide metabolite of compound alpha [5-chloro-2-methylthio-6-(1-naphthyloxy)-H-benzimidazole]; the metabolite will be referred to as alpha.SO. Changes resulting from drug treatment were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tubulin immunocytochemistry (ICC). SEM revealed that disruption to the tegumental surface mainly took the form of swelling and blebbing. Extensive spine loss occurred on the ventral surface of the oral cone, and sloughing of the tegument was observed along the lateral margins of the fluke. Examination of sections from the anterior mid-body region at the TEM level revealed that treatment with alpha.SO led to swelling of the basal infolds and mitochondria within the tegumental syncytium; also, accumulations of secretory bodies beneath the apical plasma membrane. The tegumental cell bodies contained swollen mitochondria and cisternae of granular endoplasmic reticulum, but few Golgi complexes were observed. An increase in T2 secretory bodies was observed, whilst in the T1 tegumental cells, the T1 secretory bodies had decreased in number. Immunocytochemical (ICC) studies showed that incubation with alpha.SO, ABZ.SO and TCBZ.SO did not cause significant changes to the distribution of tubulin within the tegumental syncytium of the Sligo isolate. In contrast, alpha.SO, ABZ.SO and TCBZ.SO caused severe disruption to tubulin organization within the syncytial layer of the TCBZ-susceptible Cullompton isolate. The EM results confirm that compound alpha is a Fasciolicide capable of disrupting the tegument of mature TCBZ-resistant F. hepatica; however, this was not accompanied by any change in tubulin immunoreactivity.
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Immature triclabendazole-resistant Fasciola hepatica: tegumental responses to in vitro treatment with the sulphoxide metabolite of the experimental Fasciolicide compound alpha
Parasitology Research, 2007Co-Authors: M. Mcconville, R Castillo, A Hernández-campos, G. P. Brennan, M. Mccoy, F. Ibarra, I FairweatherAbstract:Juvenile triclabendazole-resistant liver flukes, Fasciola hepatica , were incubated in vitro with 10 μg/ml of the sulphoxide metabolite of the experimental Fasciolicide, compound alpha [5-chloro-2-methylthio-6-(1-naphthyloxy)-1 H -benzimidazole], for 6 and 18 h. Following treatment, the specimens were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tubulin immunocytochemistry. The SEM results revealed a posterior-directed disruption comprised predominantly of swelling and blebbing of the tegument; these changes were more severe and extensive after the longer 18-h incubation. Along with swelling of the tegument and blebbing, the TEM results also revealed swelling of the mitochondria and basal infolds. A decrease in the number of both T1 and T2 secretory bodies was observed in the syncytium and cytoplasmic connections after the 18-h treatment. The circular muscle bundles were also disrupted, in that the organisation of the muscle fibres was irregular and the total number of muscle fibres was reduced. The immunocytochemical studies revealed no significant disruption to the distribution of tubulin immunoreactivity within the tegumental syncytium, the cytoplasmic connections or the associated tegumental cells. The results indicate that alpha.SO is capable of disrupting the tegument of 4-week-old triclabendazole-resistant liver flukes, though the morphological changes were not associated with any significant differences in tubulin immunostaining.
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Adult triclabendazole-resistant Fasciola hepatica: surface and subsurface tegumental responses to in vitro treatment with the sulphoxide metabolite of the experimental Fasciolicide compound alpha.
Parasitology, 2006Co-Authors: M. Mcconville, Rafael Castillo, Alicia Hernández-campos, G. P. Brennan, M. Mccoy, F. Ibarra, Ian FairweatherAbstract:Mature Fasciola hepatica of the triclabendazole-resistant Sligo isolate were incubated in vitro with 10 microg/ml of the sulphoxide metabolite of compound alpha [5-chloro-2-methylthio-6-(1-naphthyloxy)-H-benzimidazole]; the metabolite will be referred to as alpha.SO. Changes resulting from drug treatment were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tubulin immunocytochemistry (ICC). SEM revealed that disruption to the tegumental surface mainly took the form of swelling and blebbing. Extensive spine loss occurred on the ventral surface of the oral cone, and sloughing of the tegument was observed along the lateral margins of the fluke. Examination of sections from the anterior mid-body region at the TEM level revealed that treatment with alpha.SO led to swelling of the basal infolds and mitochondria within the tegumental syncytium; also, accumulations of secretory bodies beneath the apical plasma membrane. The tegumental cell bodies contained swollen mitochondria and cisternae of granular endoplasmic reticulum, but few Golgi complexes were observed. An increase in T2 secretory bodies was observed, whilst in the T1 tegumental cells, the T1 secretory bodies had decreased in number. Immunocytochemical (ICC) studies showed that incubation with alpha.SO, ABZ.SO and TCBZ.SO did not cause significant changes to the distribution of tubulin within the tegumental syncytium of the Sligo isolate. In contrast, alpha.SO, ABZ.SO and TCBZ.SO caused severe disruption to tubulin organization within the syncytial layer of the TCBZ-susceptible Cullompton isolate. The EM results confirm that compound alpha is a Fasciolicide capable of disrupting the tegument of mature TCBZ-resistant F. hepatica; however, this was not accompanied by any change in tubulin immunoreactivity.
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Fasciola hepatica: effects of the Fasciolicide clorsulon in vitro and in vivo on the tegumental surface, and a comparison of the effects on young- and old-mature flukes
Parasitology Research, 2003Co-Authors: M Meaney, I Fairweather, L S L Mcdowell, G. P. Brennan, A B ForbesAbstract:The ultrastructural changes in Fasciola hepatica induced by the Fasciolicide clorsulon were assessed using scanning electron microscopy. At 8 and 44 weeks post-infection, male Sprague-Dawley rats infected with F. hepatica were dosed orally with clorsulon at a concentration of 12.5 mg/kg and mature flukes recovered from the bile duct after 24 h, 48 h, and 72 h in both experiments. An in vitro incubation was also set up using mature fluke (8 weeks old) incubated with clorsulon for 24 h at a concentration of 10 μg/ml. After 24 h in vivo, the young-mature flukes (8 weeks old) showed significant disruption to the tegumental surface, particularly in the anterior mid-body region, where a distinct band of swelling and blebbing was evident. The band began just behind the ventral sucker and ran posteriorly along both margins. The apical cone region of the fluke was characterised by swelling and blebbing of the surface between the spines. Similar changes were evident after 48 h in vivo, but the disruption was more severe and the mid-body band had spread posteriorly. In approximately half of the specimens recovered after 72 h in vivo, widespread disruption had occurred, with sloughing of the apical membrane or the entire syncytium, over almost all of the oral cone and anterior mid-body. For all time periods, the anterior half of the fluke was more severely affected than the posterior half. No differences were seen between the dorsal and ventral surfaces. Old-mature flukes (44 weeks old) showed regionally similar, but more severe and widespread disruption than that seen in the young-mature flukes. The onset of surface changes occurred more quickly in old-mature flukes as well. Eight-week-old flukes which had been incubated for 24 h in vitro showed surprisingly little disruption, but this may be due to the method by which the drug is taken up by the fluke.
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Fasciola hepatica: tegumental surface alterations following treatment in vivo and in vitro with nitroxynil (Trodax)
Parasitology Research, 2003Co-Authors: B. Mckinstry, I Fairweather, G. P. Brennan, A B ForbesAbstract:Male Sprague-Dawley rats were dosed orally with nitroxynil at a concentration of 40 mg/kg and adult Fasciola hepatica recovered after 24 h, 48 h and 72 h. Surface changes to the flukes were monitored by means of SEM. After the 24 h treatment, extensive swelling and blebbing of the tegument was observed on both surfaces, although the dorsal anterior region was more severely affected than either the posterior dorsal region or entire ventral surface. At high magnification, microvillus-like projections were evident, giving the surface a roughened appearance. After 48 h, the changes evident at 24 h had become more severe and some tegumental loss had occurred in the oral region of the fluke. Surface disruption was particularly evident along the lateral margins of the fluke in this region. In some specimens a single large swelling was present in the dorsal midbody region. The swelling was a more typical feature of flukes recovered. After 72 h, tegumental loss was more widespread, occurring over the oral cone and anterior midbody on the dorsal surface. Overall the dorsal surface was consistently more severely affected than the ventral surface, and the anterior region of the fluke was more disrupted than the posterior region. After 24 h in vitro incubation, the oral cone and midbody exhibited considerable spine loss and swelling. Overall, the dorsal surface was more disrupted than the ventral surface and the anterior region of the fluke was more disrupted than the posterior region. Regional differences in the response of the fluke to nitroxynil will be compared to previously published data with other Fasciolicides. The results indicate that the tegument is an important target for nitroxynil action. Disruption of this, the fluke's main line of defence, would allow the drug access to other internal tissues, leading to more widespread damage.