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Teruaki Ikeda - One of the best experts on this subject based on the ideXlab platform.
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Effects of L-type Ca^2+ channel antagonists on in vitro excystment of Paragonimus ohirai Metacercariae induced by sodium cholate
Parasitology Research, 2006Co-Authors: Teruaki IkedaAbstract:The inhibitory effects of L-type Ca^2+ channel antagonists on Na cholate-induced in vitro excystment (CIIE) of Paragonimus ohirai Metacercariae were studied. At concentrations of 10 μM, nicardipine and nimodipine inhibited CIIE completely and by approximately 92%, respectively. Nitrendipine and (±)-verapamil inhibited CIIE by about one half and one third, respectively. Nifedipine and diltiazem did not inhibit CIIE significantly. At higher concentrations, nitrendipine at 20 μM completely inhibited CIIE, and (±)-verapamil at 40 μM inhibited CIIE by 93%. Nifedipine and diltiazem inhibited CIIE only slightly and little, respectively, even at 40 μM. Complete inhibition by nicardipine at 10 μM required preincubation of Metacercariae with the antagonist for 15 min. The inhibitory effects of nicardipine and nimodipine were reversible, and most of the nimodipine-treated Metacercariae could excyst within 1 h after being washed, but the nicardipine-treated ones started to excyst 1 h after washing. Nicardipine suppressed the active movement of encysted juveniles evoked by Na cholate, whereas nimodipine did not suppress this significantly. These results suggested that L-type Ca^2+ channels appeared to be involved in CIIE of P. ohirai Metacercariae and that the inhibitory effect of the channels was due primarily to factors other than the inhibition of muscular activity, probably involving the secretion and release of enzymes lytic against the metacercarial cyst wall.
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Effects of blockers of Ca^2+ channels and other ion channels on in vitro excystment of Paragonimus ohirai Metacercariae induced by sodium cholate
Parasitology Research, 2004Co-Authors: Teruaki IkedaAbstract:The inhibitory effects of various ion channel blockers were examined on in vitro excystment of Paragonimus ohirai Metacercariae induced by a bile salt, sodium cholate. At a concentration of 10 µM, bepridil, a non-selective Ca^2+ channel blocker, completely inhibited in vitro excystment, whereas TEA, lidocaine, and R(+)-IAA-94, channel blockers against K^+, Na^+ and Cl^− ions, respectively, benzamil, an Na^+/H^+ and Na^+/Ca^2+ ion exchanger blocker, and R(+)-DIOA, a [K^+, Cl^−] cotransporter inhibitor, did not. Considering the previous result that Ca^2+ ionophores are also efficient inducing factors for in vitro excystment of P . ohirai Metacercariae and the present result, bile salts appear to induce the excystment of P . ohirai Metacercariae through evoking the Ca^2+ channels of target cells within the metacercarial juveniles.
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Effect of ionophores on in vitro excystment of Paragonimus ohirai Metacercariae
Parasitology Research, 2001Co-Authors: Teruaki IkedaAbstract:Ca2+ ionophores (A23187 and ionomycin) induced in vitro excystment of Paragonimus ohirai Metacercariae, whereas Na+ ionophore (monensin) and K+ ionophores (nigericin and valinomycin) did not. The effect of A23187 on in vitro excystment was dependent on the concentration of the ionophore. A high concentration of 1 μM or more induced rapid excystment, but resulted in the death of metacercarial juveniles. The appropriate concentration of 0.2 μM induced in vitro excystment by 5 h after incubation with little or no damage to the juveniles.
Bernard Fried - One of the best experts on this subject based on the ideXlab platform.
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An update on metacercarial excystment of trematodes
Parasitology Research, 2009Co-Authors: Tyler Saxton, Bernard FriedAbstract:This review updates an earlier one by Fried (Adv Parasitol 33:91–144, 1994 ) on metacercarial excystation of trematodes. Our coverage of the salient literature is mainly from 1995 to 2008 and includes significant studies on echinostomatid and non-echinostomatid trematodes. Most of the echinostomatid studies are on species of 37-collar spined Echinostoma , although one study is concerned with a species of Echinochasmus . The non-echinostomatid coverage includes work on species of Paragonimus , Haplorchis , Apatemon , Microphallus , Clonorchis , Riberoia , Maritema , Opisthorchis , and Zygocotyle . Most of the studies were concerned with methods used to excyst the Metacercariae of the species being investigated. However, some studies were concerned with metacercarial excystation in order to use the excysted larvae for in vitro cultivation or morphometric studies. Other studies used the excysted larvae for physiological, biochemical, or behavioral work. Several studies were also concerned with elucidating both intrinsic and extrinsic factors which mediate chemical excystation of the metacercarial stage of digenetic trematodes
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Association of bacteria with metacercarial cysts of Echinostoma caproni
Parasitology Research, 2007Co-Authors: Shamus P. Keeler, Bernard Fried, Jane E. HuffmanAbstract:Echinostoma caproni metacercarial cysts often need to be stored for several months to a year to meet laboratory requirements. This study examined the bacteria associated with encysted Metacercariae stored at 4°C. Bacterial assemblages from the kidney-pericardial region of uninfected snails and assemblages from the site of metacercarial infection in Biomphalaria glabrata were determined. Four species of Gram-negative rods were isolated and identified from the stored cysts to species or genus as Pseudomonas sp., Alcaligenes sp., Enterobacter cloacae, and Aeromonas hydrophila. Gram-positive rods were also isolated and included small slender rods (alpha hemolytic), small coccobacilli (gamma hemolytic), and small rods that exhibited gamma hemolysis. Accumulation of these bacteria on the surface of encysted Metacercariae probably contributed to a decreased cyst viability of E. caproni.
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Excystation and distribution of Metacercariae of Echinostoma caproni in ICR mice
Comparative Parasitology, 2001Co-Authors: Bernard Fried, Aditya Reddy, Caroline D. BalfourAbstract:In vivo excystation and distribution of newly excysted Metacercariae of Echinostoma caproni Richard, 1964, were studied in 16 ICR mice, each fed 400 metacercarial cysts and necropsied at various intervals from 1 to 24 hr postinfection (p.i.). Excysted Metacercariae were recovered from the stomach and intestine (duodenum and jejunum) at 1 hr p.i. In vivo excystation in this echinostome occurred in the stomach and the anterior part of the small intestine. Encysted Metacercariae were recovered from the stomach, small intestine, and cecum-large intestine at 1 and 2 hr p.i. Recovery of encysted Metacercariae was rare at 3 hr and nil at 4 and 24 hr. At 3, 4, and 24 hr, the encysted Metacercariae had either excysted or were voided. Excysted Metacercariae were widely scattered throughout the small intestine at all times, with about 75% located in segments 1, 2, and 3 (duodenal-jejunum zone) of the small intestine at 3, 4, and 24 hr p.i.
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Postmetacercarial changes in Echinostoma caproni maintained in a defined medium plus calf serum.
Korean Journal of Parasitology, 2000Co-Authors: Bernard Fried, Aditya ReddyAbstract:Echinstoma caproni is a good model for various studies on the biology of Echinostoma and echinostomiasis. The life cycle of this echinostome is easily maintained in the laboratory between Biomphalaria glabrata snails and Institute of Cancer Research (ICR) mice (see Fried and Huffman, 1996 for review). Although excysted Metacercariae of this echinostome have been cultivated to ovigerous adults in chick embryos (Chien and Fried, 1992), surprisingly little work has been done on the in vitro maintenance or cultivation of the metacercarial stage of this echinostome. The encysted Metacercariae of this species are easy to excyst in vitro in an alkaline trypsin-bile salts medium as described in Ursone and Fried (1995); therefore, excysted Metacercariae are readily available to initiate in vitro cultivation or maintenance studies. The excysted metacercaria contains an abundant number of excretory concretions (calcareous corpuscles) in the protonephridial tubules as seen in Figure 15 in Fried and Huffman (1996). From observations of worms grown in chicks and mice, it is apparent that the excretory concretions are not present in the adults of E. caproni. Thus, they are probably voided between the metacercarial and adult stages. A purpose of the in vitro maintenance study reported herein was to note the disappearance of these concretions and also report other findings. Metacercariae of E. caproni were removed from experimentally infected B. glabrata snails and chemically excysted in an alkaline trypsin-bile salts medium at 41℃ as described in Ursone and Fried (1995). Excysted Metacercariae were transferred through three changes of sterile Locke's solution containing 200 units penicillin/ml and 200 µg streptomycin/ml. The medium used to maintain the excysted Metacercariae was the defined medium Mixture 199 + 20% calf serum (Mix 199 + 20 CS). The medium was fortified with penicillin/streptomycin as described for the Locke's solution. All chemicals were purchased from Sigma (St. Louis, MO, USA). Cultures were done in 15 ml plastic centrifuge tubes containing 10 ml of the medium. The cultures were capped and maintained upright in an incubator at 41℃ for up to 7 days. The gas phase was atmospheric air. Each culture was inoculated with 25 excysted Metacercariae at the start of the experiment and one culture per day was examined for 7 days. All Metacercariae examined were alive until 4 days post-inoculation. Many of the Metacercariae were attached to each other in a clump at the bottom of the tubes, but some Metacercariae were solitary. Metacercariae began to void their excretory concretions by day 1 so that by day 2, most Metacercariae contained 4 to 8 concretions. By 2 days the collar and tegumentary spines were flared out, making them more visible than spines seen in the excysted Metacercariae. By 4 days in culture, most excysted Metacercariae were completely devoid of excretory concretions (Fig. 1) and some contained bumps or protuberances (Fig. 2); others contained a vacuolar bleb in the posterior aspect of the organism (Fig. 3). Some mortality was seen by day 5 with 5 of the 25 metacerariae being dead. Mortality increased to 10 of 25 dead organisms by 7 days of culture at which time the cultures were terminated. The surviving organisms looked the same at 7 days as they did at 4 days with some also showing bumps, protuberances, and blebs and all being devoid of the excretory concretions. Figs. 1-3 Light micrographs of excysted metacercaria of Echinostoma caproni maintained for 4 days in Mixture 199 plus 20% calf serum. Fig. 1. Intact organism showing the absence of excretory concretions. Fig. 2. Organism showing the flaring of the oral collar and ... There has been a decline in studies on the in vitro cultivation or maintenance of digeneans. Reasons for the decline have been discussed by Irwin (1997). In brief, these studies are labor intensive and often give negative results which are not publishable. The present study used a defined medium supplemented with calf serum to examine some postmetacercarial changes in E. caproni, i.e., voidance of the excretory concretions and development of body protuberances in vitro. Future in vitro studies on this and other echinostomes may provide interesting information on the many transformational events that must occur in the development from the metacercarial to the adult stage. In conclusion, no sexual organs appeared in 6- or 7-day-old worms. Therefore, although some somatic changes were observed, there were no indications of germinal changes in worms maintained under our in vitro conditions. Cultures were terminated at day 7 post-incubation because the culture conditions were becoming unfavorable, and many worms were dead. The appearance of the blebs, protuberance, and vesicles in the worms may be an indication of worm degeneration in an inhospitable environment. Although some digeneans have been maintained in the serum-free cultures, attempts to cultivate the excysted Metacercariae of E. caproni in serum-free media were not made in our study.
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Neutral lipids in cercariae, encysted Metacercariae, and rediae of Zygocotyle lunata.
The Journal of Parasitology, 2000Co-Authors: Carmen J. Marsit, Bernard Fried, Joseph ShermaAbstract:High-performance thin-layer chromatography was used to analyze the neutral lipids in the rediae, cercariae, and encysted Metacercariae of the paramphistomid trematode Zygocotyle lunata. Visual observations of the chromatograms showed that the most abundant lipid fractions were free sterols and free fatty acids in all larval stages and triacylglycerols in the Metacercariae and rediae. The weight of free sterols (x ± SE) was 120 ± 20 ng/cercaria, 56 ± 3.8 ng/redia, and 5.9 ± 1.5 ng/encysted metacercaria; the weight of triacylglycerols was 13 ± 0.88 ng/encysted metacercaria, 6.3 ± 0.063 ng/redia, and was not detectable in the cercaria; the weight of free fatty acids was 160 ± 17 ng/cercaria, 76 ± 9.1 ng/redia, and 4.2 ± 0.46 ng/encysted metacercaria. Oil red O staining of whole larvae showed the presence of neutral lipids in the rediae but not in the cercariae or encysted Metacercariae. A dramatic reduction was seen in the quantity of free sterols and free fatty acids in the encysted Metacercariae as compar...
Kurt Buchmann - One of the best experts on this subject based on the ideXlab platform.
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Import of exotic and zoonotic trematodes (Heterophyidae: Centrocestus sp.) in Xiphophorus maculatus: Implications for ornamental fish import control in Europe
Acta Parasitologica, 2014Co-Authors: Foojan Mehrdana, Per W Kania, Hannah M. Jensen, Kurt BuchmannAbstract:Ornamental fish, Xiphophorus maculatus , were imported from Singapore to Denmark for distribution to local aquarists. Importers observed lethargic and erratic swimming patterns among fish and forwarded a total of 30 fish for pathological examination to a university diagnostic service. All fish were diagnosed infected with encysted Centrocestus sp. Metacercariae in gills (prevalence of 100% and mean intensity of 454.5 ± 161.9 parasites per fish). Metacercariae were identified by morphological and molecular methods. Cysts (mean length 163.3 ± 13.7 μm and mean width 113.3 ± 10.6 μm) contained a bent metacercaria with an X-shaped excretory bladder. PCR amplification of a rDNA region (5.8S rRNA gene, ITS-2, 28S rRNA gene) and subsequent sequencing confirmed the diagnosis. Metacercariae were found in gill filaments adjacent to the cartilage associated with cartilage hypertrophy, epithelial and mucous cell hyperplasia, clubbing and lamellar fusion. Host cell encapsulation of cysts comprised several layers of leucocytes, chondroblast-like and fibroblast-like cells. The observations raise concerns with regard to veterinary inspection and quarantine procedures. The zoonotic potential of these trematodes and a possible spread of the parasites in natural habitats in Europe should be regarded as a public health issue. So far, several cases of human infections have been reported only in Asia, but the potential intermediate host snail, Melanoides tuberculata , has been recorded in Germany. Accordingly, establishment of the parasite in Europe with climate changes should be considered a risk.
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molecular and morphometric study of Metacercariae and adults of pseudamphistomum truncatum opisthorchiidae from roach rutilus rutilus and wild american mink mustela vison
Veterinary Parasitology, 2008Co-Authors: Jakob Skov, Per W Kania, Thomas R Jorgensen, Kurt BuchmannAbstract:The presence of Metacercariae and adults of the trematode Pseudamphistomum truncatum in roach and mink, respectively, was recorded in Lake Fure North of Copenhagen, Denmark. This zoonotic digenean opisthorchiid represents a threat to humans due to its ability to infect the biliary system following ingestion of inadequately processed infected fish. Therefore precise species identification of infective Metacercariae in fish used for human consumption is essential. Due to the relatively limited information on metacercarial identity obtained by morphometric studies a series of molecular techniques were used to link the larval parasite in fish with the un-equivocally diagnosed adults in the biliary system of the mink. By the use of carefully selected polymerase chain reaction (PCR) primers and subsequent sequencing of the ITS region from both Metacercariae and adults full sequence identity of both Metacercariae and adults were confirmed. The presence of this parasitosis in fish from a lake used for both commercial and recreational fisheries call for hygienic alerts in order to prevent accidential human infection with this opisthorchiid.
Monica Caffara - One of the best experts on this subject based on the ideXlab platform.
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A new species of Clinostomum Leidy, 1856 based on molecular and morphological analysis of Metacercariae from African siluriform fishes
Parasitology Research, 2020Co-Authors: Monica Caffara, Sean A. Locke, Paul C. Echi, Ali Halajian, Willem J. Luus-powell, Deborah Benini, Perla Tedesco, Maria L. FioravantiAbstract:In the Afrotropic region, the genus Clinostomum is represented by four accepted and four unnamed species distinguished using molecular data. Here, we describe one of the four unnamed species as Clinostomum ukolii n. sp. based on Metacercariae from siluriform fishes ( Synodontis batensoda , Schilbe intermedius ) collected in Nigeria and South Africa. The new species is distinguished by molecular data (39 new sequences of partial cytochrome c oxidase I ≥ 6.7% divergent from those of other species) and morphological differences from named and unnamed species in the same region. Metacercariae of C. ukolii n. sp. can be distinguished based on size, tegumental spines, and various aspects of the genital complex, including its position, lobation of the anterior testis, and the disposition and shape of the cirrus pouch. Although descriptions of new species of digeneans are typically based on the morphology of adults, we argue that in cases where data are available from Metacercariae from regionally known species, new species can be described based on Metacercariae, particularly when supported by molecular data, as here. Moreover, sub-adult reproductive structures can be clearly visualized in metacercaria of Clinostomum . Considering Metacercariae as potential types for new species could advance clinostome systematics more rapidly, because Metacercariae are encountered much more often than adults in avian definitive hosts.
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development and validation of species specific molecular diagnostic tool for opisthorchis felineus digenea opisthorchiidae Metacercariae
International Journal of Food Microbiology, 2017Co-Authors: Monica Caffara, Laura Serracca, Andrea Gustinelli, Walter Vencia, Irene Rossini, M Prearo, Marialetizia FioravantiAbstract:Opisthorchis felineus (family Opisthorchiidae) is a parasitic flatworm representing a serious threat to humans in some countries. Opisthorchiasis occurs after consumption of raw or undercooked cyprinid fish infected by the metacercarial stage of the parasite. Due to its small size, detection of the parasite in fish fillet is time-consuming and difficult. Furthermore, isolated Metacercariae can be identified to genus but not to species level using morphological features and molecular techniques are necessary. In this work, we describe the development of primers for a diagnostic PCR amplification of a 254-bp fragment of the cytochrome c oxidase I in the mitochondrion of Opisthorchis felineus Metacercariae isolated from fish fillet, together with a validation protocol for this method.
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redescription of clinostomum phalacrocoracis Metacercariae digenea clinostomidae in cichlids from lake kinneret israel
Parasite, 2014Co-Authors: Monica Caffara, Andrea Gustinelli, Nadav Davidovich, Rama Falk, Margarita Smirnov, Tamir Ofek, David Cummings, Marialetizia FioravantiAbstract:Clinostomidae are digeneans characterized by a complex taxonomic history, continuously under revision based on both morphological and molecular analysis. Among the 14 species considered valid so far Clinostomum phalacrocoracis has been well described only at the adult stage, whereas the morphology of the metacercarial stage has been reported only once. During a parasitological survey carried out on 262 wild cichlids sampled from Lake Kinneret (Israel) Metacercariae referable to C. phalacrocoracis were found in 18 fingerlings. In this study, we report this clinostomid species for the first time in wild fish from Israel describing the metacercarial stage of Clinostomum phalacrocoracis, coupling its morphological description with molecular analysis carried out on ITS rDNA and COI mtDNA sequences.
Van Thi Phan - One of the best experts on this subject based on the ideXlab platform.
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The importance of wild fish in the epidemiology of Clonorchis sinensis in Vietnam
Parasitology Research, 2016Co-Authors: Thanh Thi Pham, Darwin Murrell, Nguyen Thi Nguyen, Ha Van Nguyen, Van Thi PhanAbstract:Preliminary findings of a high prevalence of Clonorchis sinensis in wild-caught fish in a North Vietnam reservoir (Thac Ba reservoir, Yen Bai Province) prompted a longitudinal epidemiological study of fish infections. Monthly collections of fish from September 2014 to August 2015 were processed for recovery of Metacercariae; 1219 fish, representing 22 species, were examined. Seven species were infected with C. sinensis Metacercariae. Four species, Toxabramis houdemeri , Hemiculter leucisculus , Cultrichthys erythropterus , and Culter recurvirostris , had high prevalence (31.1 to 76.7 %); metacercarial intensities ranged from 3.9 to 65.7 Metacercariae/fish. A seasonal variation of C. sinensis prevalence was observed in T. houdemeri . Variation in intensity of infection occurred in C. erythropterus and H. leucisculus . Intensity and prevalence of C. sinensis in the most highly infected species, T. houdemeri , varied by fish size; prevalence was higher in fish weighing more than 3 g, and intensity was higher in fish weighing more than 5 g. The distribution of Metacercariae in the body region of T. houdemeri was significantly higher in the caudal fin (14.7 Metacercariae/g), compared to the body and head regions (0.7 and 1.4 Metacercariae/g, respectively). Further epidemiological investigations on C. sinensis in this reservoir region should include assessing the relative risk of the different fish species for humans based on the latter’s food preferences, and the prevalence of C. sinensis in the community. The snail intermediate host(s) in the reservoir should also be identified along with the ecological factors influencing its exposure to C. sinensis eggs and its subsequent transmission of cercariae to fish. Also needed are investigations on the relative importance of wild and domestic reservoir hosts as sources of egg contamination of the reservoir.