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trematodes of the family opisthorchiidae: a minireview.examination of the original descriptions of genera placed within the family opisthorchiidae has revealed that only 33 of the original 43 genera are valid members of this family. further study of these descriptions should also reveal that many of the subfamilies are also invalid. with reference to the original descriptions of these genera, and subsequent literature, a brief survey of the family has been compiled. information on the spectrum of definitive hosts that these helminths parasitize is p ...200111590910
analysis of laci mutations in big blue transgenic mice subjected to parasite-induced inflammation.parasite infections have long been associated with specific types of human cancers. schistosoma hematobium is an inducer of urinary bladder cancer, helicobacter pylori is a gastric carcinogen, and hepatitis b virus and opisthorchis viverrini are causative agents of hepatocellular carcinoma. another liver fluke, fasciola hepatica, has also been identified as a neoplastic risk agent, primarily in animals. we used f. hepatica-induced inflammation in mice to determine if the presence of an aggressiv ...200111733073
parasitic infections and hepatic neoplasia.parasitic infections are highly prevalent in the general population. detecting a relationship between a parasitic infection and cancer is not an easy task; it requires epidemiological, microbiological and molecular biology techniques. in this article the important mechanisms by which parasitic infections may induce carcinogenesis are reviewed. the association between schistosoma japonicum, schistosoma mansoni and hepatocellular carcinoma is covered. the cause-and-effect relationship between the ...200111935088
development of a pcr-based method for the detection of opisthorchis viverrini in experimentally infected hamsters.opisthorchis viverrini infection is an endemic disease that causes a serious public health problem in southeast asia, especially in northeast thailand. we have developed a pcr method using a pair of primers named ov-6f/ov-6r for detecting o. viverrini eggs in stool samples and compared it with stoll's egg-count method. the primers were designed based on the pov-a6 specific dna probe sequence which gave a 330 base pair product. the pcr method can detect a single egg in artificially inoculated fae ...200111272648
intestinal parasitic infections in thai hiv-infected patients with different immunity status.one of the major health problems among hiv seropositive patients is superimposed infection due to the defect of immunity. furthermore, intestinal parasite infection, which is also one of the basic health problems in tropical region, is common in these patients. in this study, a cross sectional study to document the prevalence of intestinal parasitic infection in thai hiv-infected patients with different immune status was performed.200111394966
ultrastructural and immunohistochemical analysis of cholangiocarcinoma in immunized syrian golden hamsters infected with opisthorchis viverrini and administered with dimethylnitrosamine.utilizing the experimental model in syrian golden hamsters, we explored the role of immunization in carcinogenesis. the animals, which were infected with liver flukes (opisthorchis viverrini), and administered a subcarcinogenic dose of dimethylnitrosamine, developed cancer. pre-immunizing with a crude somatic antigen did not reduce cancer development, but accelerated carcinogenesis. histopathological analysis of the cancer tissues was done once at week 30 and again at week 39 using h and e stain ...200011426579
promotion of the health of rural women towards safe motherhood--an intervention project in northeast thailand.an intervention project focusing on the health of women in the reproductive age was conducted in three districts of khon kaen province, northeast thailand between 1991 and 1996. main emphasis was placed on improving reproductive health, the nutritional status including the iron deficiency anemia (ida) as well as iodine deficiency disorders (idd), and the parasitic diseases liver fluke (opisthorchis viverrini) and hookworm. for implementation a community based primary health care approach was use ...200011488446
investigation on subclinical aspects related to intestinal parasitic infections among thai laborers in taipei.the migration of foreign workers from developing regions to developed countries may potentially lead to transmission of intestinal parasitic infections. in order to determine the relationship between intestinal parasitic infections and the health status of foreign workers, 302 thai laborers brought to taiwan were examined in this study. nine species of parasites were found in 64.9% of laborers; opisthorchis viverrini, hookworm, strongyloides stercoralis, giardia lamblia, trichuris trichiura, fas ...200011305242
opisthorchis viverrini: ultrastructure and cytochemistry of the glycocalyx of the tegument.the ultrastructure and cytochemistry of the glycocalyx of the tegument of opisthorchis viverrini during maturation from newly excysted juvenile to adult stages were investigated using colloidal iron, ruthenium red and lectin stainings. the results showed that the glycocalyx was intensely stained by the first two dyes, thus indicating the presence of relatively high amounts of negative charges. however, the thickness and intensity of the staining decreased during the fluke's maturation. binding s ...200010831050
localisation of parasite antigens and inflammatory responses in experimental opisthorchiasis.the time course localisation of parasite antigens and related host pathology were studied in hamsters infected with 100 metacercariae of opisthorchis viverrini for up to 6 months. parasite antigens, as detected by immunofluorescence and/or immunoperoxidase-staining, were first observed in the flukes and the biliary epithelium of the intrahepatic and extrahepatic bile ducts as early as day 3 p.i. antigens increased as the parasite matured, both in tissues in direct contact with the flukes and tho ...200010856508
partial characterization of a 17 kda protein of clonorchis sinensis.a 17 kda protein from clonorchis sinensis adults was purified by a procedure including sephacryl s-200 hr gel filtration and q-sepharose anion exchange chromatography. the protein was proved to be a cysteine protease as it showed hydrolytic activity toward cbz-phe-arg-amc in the presence of dithiothreitol and was inhibited by specific inhibitors such as iodoacetic acid or trans epoxy-succinly-l-leucyl-amido(4-guanidino) butane. the polyclonal antibody raised against the protein reacted to 17 kda ...200010905071
an epidemiological study on opisthorchis viverrini infection in lao villages.the prevalence of liver fluke, opisthorchis viverrini, infection in rural and urban communities was studied in khammouane province in lao pdr. the infection was the commonest among the villagers examined, showing the positive rates of 52.9% and 55.0% in two rural communities and 60.7% in an urban community, respectively. the infection rate reached up to 20% or more within 4 years after birth and increased with age to a plateau in the age group over 20 years. the highest prevalence rate was over ...200011023079
relationship between parasite-specific antibody responses and intensity of opisthorchis viverrini infection in hamsters.the kinetics of parasite-specific antibody responses in relation to worm burden and egg output were investigated in hamsters infected with 25, 50 and 100 opisthorchis viverrini metacercariae (mc). levels of antibody to egg, excretory-secretory (es) and somatic antigens were examined by elisa on days 1, 3, 7, 14 and month 1 postinfection (p.i.), and repeated monthly up to 6 months. the antibody responses were first detected as early as 14 days after infection. hamsters that were infected with 100 ...200010672195
current status of infection-related gastrointestinal and hepatobiliary diseases in thailand.the objective of this overview is to assess the present situation with regards to gastrointestinal and hepatobiliary diseases prevailing in thailand. in that context, special emphasis has been put on those forms of viral hepatitis prevalent in the region, namely, hepatitis a the frequency of which has undergone a change from hyper- to hypoendemic with a resulting decline in naturally acquired immunity; hepatitis b with its tendency to cause chronic liver disease mainly due to asymptomatic infect ...199910695796
chromosomes and c-banding of opisthorchis viverrini.chromosome of opisthorchis viverrini was observed by air-drying and c-banding techniques. the chromosome number was 2n=12 and n=6 consisting of one large-sized metacentric, one medium-sized metacentric, one small-sized metacentric, one small-sized submetacentric or subtelecentric, one small-sized subtelocentric or acrocentric and one small-sized acrocentric. the relative lengths of the chromosomes were 32.02 +/- 2.52, 23.28 +/- 1.98, 15.24 +/- 3.40, 13.39 +/- 3.11, 10.18 +/- 1.56 and 5.82 +/- 0. ...199910774673
prevalence of trematode metacercariae in cyprinoid fish of ban pao district, chiang mai province, northern thailand.the prevalence of trematode metacercariae in natural cyprinoid fish was carried out in ban pao district, chiang mai province, northern thailand. fish were collected from both man-made water reservoirs and natural sources during july 1996-may 1997. nine species of cyprinoid fish harbored the metacercariae of opisthorchis viverrini and small intestinal flukes of the family heterophyidae, ie haplorchis taichui, h. pumilio and centrocestus spp. metacercariae of h. taichui were found approximately 38 ...199910774710
potassium permanganate staining for differentiation the surface morphology of opisthorchis viverrini, haplorchis taichui and phaneropsolus bonnei eggs.potassium permanganate staining method was developed for differentiation opisthorchis viverrini, haplorchis taichui and phaneropsolus bonnei eggs. the surfaces of o. viverrini, h. taichui and p. bonnei eggs stained permanently and temporarily were similar in appearance even the staining procedures were varied both in concentration and time. determined under light microscope set at 400x, all of these eggs were oval-shaped, operculated at one pole and indistinct small knob at posterior end. o. viv ...199910774711
volatile nitrosamines and tobacco-specific nitrosamines in the smoke of thai cigarettes: a risk factor for lung cancer and a suspected risk factor for liver cancer in thailand.in thailand, smoking of commercial cigarettes and of handmade cigarettes has drastically increased in recent decades. cancer of the lung and of the upper aero-digestive tract have also increased in thailand as they have in many other countries. it is our working hypothesis that the increase of primary cancer of the liver, especially of cholangiocarcinoma in the north-eastern provinces of thailand is associated with the use of tobacco in men infested with the liver fluke opisthorchis viverrini (o ...19999934860
exposure to n-nitroso compounds in a population of high liver cancer regions in thailand: volatile nitrosamine (vna) levels in thai food.the recent case-control studies in thailand indicate that a high incidence of liver cancer in thailand has not been associated with common risk factors such as hepatitis b infection, aflatoxin intake and alcohol consumption. while the infestation by the liver fluke opisthorchis viverrini (ov) accounted for the high risk in north-east thailand, there was no such exposure in the other regions of the country where the incidence of liver cancer is also high. case-control studies suggest that exposur ...199910418946
mechanisms of biliary carcinogenesis: a pathogenetic multi-stage cascade towards cholangiocarcinoma.carcinomas of the biliary tract are rare cancers developing from the epithelial or blast-like cells lining the bile ducts. a variety of known predisposing factors and recent experimental models of biliary carcinogenesis (e.g., infection with the liver fluke opisthorchis viverrini, models of chemically induced carcinogenesis and experimental models of pancreaticobiliary maljunction) have elucidated different stages of this complex system of biliary tumorigenesis. chronic inflammatory processes, g ...199910436802
use of delipidized antigens of taenia solium metacestodes in igg-elisa for detection of neurocysticercosis.the development of igg-elisa for detecting neurocysticercosis is aimed at the routine laboratory, and requires a particular antigen preparation, an acceptable number of serum samples to be tested (both homologous and heterologous) and patients with a diversity of helminthic infections to rule out cross-reactions. this study characterizes igg-antibodies from cases of neurocysticercosis by assaying the sera against ether-delipidized antigens (5 microg/ml) prepared from metacestodes of taenia soliu ...199810437960
an epidemiological survey on intestinal parasite infection in khammouane province, lao pdr, with special reference to strongyloides infection.to estimate the current prevalence of intestinal helminth infection in lao pdr, a parasitological survey was conducted in three villages in khammouane province in december 1996, with special reference to strongyloides infection. a total of 669 fecal samples were collected in the villages and examined by agar-plate culture method and kato-katz thick smear method. intestinal helminths were demonstrated in 82% of the samples as follows: ascaris lumbricoides (30.5%), trichuris trichiura (23.7%), hoo ...199810772552
relationships between the synthesis of n-nitrosodimethylamine and immune responses to chronic infection with the carcinogenic parasite, opisthorchis viverrini, in men.this study investigated the relationship between immune responses to infection with the liver fluke, opisthorchis viverrini, and the synthesis of the carcinogen, n-nitrosodimethylamine (ndma) in humans. it also examined associations between synthesis of nitric oxide (no) and nitrosation of amines, in vivo. antibody and t cell responses to fluke antigens and post-alcohol urinary ndma excretion were assessed among three groups of 40-50 men with no, moderate and heavy liver fluke infection. markers ...19989525284
parasitic infections among southeast asian labourers in taiwan: a long-term study.parasitic infections have been reported to be relatively common among the southeast asian labourers in taiwan. this study, conducted in 1992-6, was designed to determine the temporal changes of the prevalence. faecal specimens were examined by the formalin-ethyl acetate sedimentation technique and blood samples screened using the quantitative buffy coat technique and confirmed by giemsa stained blood smear. the overall prevalence of intestinal parasitic infections was 10.3%. the annual prevalenc ...19989528821
a small-scale survey of intestinal helminthic infections among the residents near pakse, laos.a small-scale epidemiological survey was undertaken on the residents along the mekong river near pakse, laos, to know the status of helminthic infections. a total of 137 fecal samples were collected from the staffs of the provincial government, their family, and primary schoolchildren in pakse city, champassak province, and examined by kato-katz smear technique. the overall helminth positive rate was 75.9%, and the helminths detected were opisthorchis viverrini (43.8%). ascaris lumbricoides (26. ...19989529864
bacterial and parasitic cholangitis.bacterial cholangitis is a clinically defined syndrome caused by the regurgitation of infected bile into the circulation. the pathogenic mechanism is unclear, and systemic sepsis may not occur. prerequisite conditions are the presence of microorganisms in the bile and increased biliary pressure. bacteria that commonly cause cholangitis are escherichia coli, klebsiella, enterococcus, enterobacter, pseudomonas, and anaerobes. although most infections are polymicrobial, this situation may not alway ...19989581592
enhanced liver cell mutations in trematode-infected big blue transgenic mice.parasite infections in humans have long been associated with specific types of cancers. schistosoma hematobium is a known inducer of urinary bladder cancer, helicobacter pylori is a gastric carcinogen, and hepatitis b virus and opisthorchis viverrini are causative agents of liver cell cancers. another liver fluke, fasciola hepatica, has also been identified as a neoplastic risk agent, primarily in animals. we used f. hepatica as a model agent to determine if the presence of an aggressive liver f ...19989685695
opportunistic protozoa in stool samples from hiv-infected patients.a retrospective study of stool samples of hiv-infected patients from january 1994 to december 1995 submitted to the department of tropical pathology was analyzed. there were twenty-two cases, all of which presented with chronic diarrhea. result showed that 50% were infected with protozoa. these include microsporidium (27.27%), cryptosporidium (9.09%), isospora belli (4.54%) and giardia intestinalis cysts (9.09%). other infections were candida sp, strongyloides stercoralis larva and opisthorchis ...19989740264
opisthorchiasis and intestinal fluke infections in northern thailand.four hundred and thirty-one residents from 16 provinces in northern thailand who had previously been found positive for opisthorchis viverrini or opisthorchis viverrini-like eggs were given praziquantel 40 mg/kg. the stool was collected for 4 to 6 times and examined for adult worms. the prevalence of opisthorchis viverrini in this group was 11.6%. intestinal flukes, haplorchis taichui and haplorchis yokogawai, were predominantly found in 63.11% and 10.44% respectively. other intestinal flukes (c ...19989740284
brief survey of common intestinal parasites in the tokyo metropolitan area.since 1955, when sanitary conditions were poor, the incidence of intestinal parasitism has steadily decreased. similarly, the number of requests for fecal examinations by physicians has also decreased. however, in our hospital, the incidence of parasites detected in fecal material has been increasing since 1994, regardless of the decreasing number of stool exams performed. possible reasons for this situation can be summarized as follows: first, an effective drug for treating trichuris trichiura ...19989796183
specific gravity of opisthorchis viverrini eggs.the specific gravity of the eggs of the liver fluke opisthorchisviverrini was determined using a sucrose gradient centrifugation and found to range from 1.2713 to 1.3043. the peak egg count was located at the sucrose fraction with a specific gravity of 1.2814. an attempt to float eggs in saturated sodium nitrate solution, sp.gr. 1.4, failed. examination of human stool specimens for oviverrini eggs by simple flotation in saturated sodium nitrate solution and the formol-ether sedimentation techniq ...19989858635
treatment of opisthorchis viverrini and intestinal fluke infections with praziquantel.the study was carried out from september to november 1997 in phrae province of northern thailand. a total of 95 adult patients with opisthorchis-like ova in their stools were randomly treated with two different manufactured praziquantels. group 1, consisting of 49 patients, received a single dose of 40 mg per kg praziquantel manufactured by the thai government pharmaceutical organization. group 2 (46 patients) received biltricide at the same dosage. haplorchis taichui, h. yokogawai, echinostome ...19989886106
opisthorchis viverrini metacercaria in thai freshwater fish.examination for metacercaria in freshwater fish, the common intermediate hosts of opisthorchis viverrini was carried out during 1992-1996. the 4-year survey of fish from markets in 14 provinces revealed that metacercariae of o. viverrini were found in fish from udon thani, sa kaeo and prachin buri provinces; fish from aranyaprathet district had the highest positive rates (25-28%). fish from 12 provinces were found to be positive with heterophyid metacercariae, namely: haplorchis pumilio, h. taic ...19989886121
epidemiology of opisthorchiasis and national control program in thailand.opisthorchiasis is a disease caused by opisthorchis trematode commonly known as liver fluke. in thailand opisthorchis viverrini is the only parasite of opisthorchiasis, the first case of opisthorchiasis was reported in 1911 by leiper from the autopsy of corpse in chiang mai. later on sadun in 1953, harinasuta and vajjarasthira in 1961, and wykoff in 1965 had demonstrated a complete life cycle of o. viverrini. history of opisthorchiasis control has dated back to 1950 as a small scale helminthiosi ...19989886122
modulation of dihydroxy-di-n-propylnitrosamine-induced liver lesion development in opisthorchis-infected syrian hamsters by praziquantel treatment in association with butylated hydroxyanisole or dehydroepiandrosterone administration.the effects of praziquantel coupled with dehydroepiandrosterone (dhea) or butylated hydroxyanisole (bha) administration 16 weeks subsequent to dihydroxy-di-n-propylnitrosamine (dhpn) treatment and infection with opisthorchis viverrini (ov) on lesion development in the liver of syrian hamsters were investigated. animals were given 80 ov metacercariae and then two i.p. injections of dhpn (500 mg/kg body weight) 4 and 5 weeks thereafter. at week 16, groups received praziquantel (250 mg/kg, i.g.) an ...19989914779
application of hazard analysis critical control point (haccp) as a possible control measure for opisthorchis viverrini infection in cultured carp (puntius gonionotus).opisthorchiasis due to opisthorchis viverrini and transmitted through infected freshwater cyprinoid fish (carps) affects more than 8 million people in thailand, people's democratic republic of lao, and vietnam. the hazard analysis critical control point (haccp)-concept has been recommended by fao and who to be included in programs to control foodborne trematode infections (fbt). haccp is a multifactorial approach to control food hazards through surveillance of diseases, foods, and operations and ...19979656352
metacercariae isolated from cyprinoid fishes in khon kaen district by digestion technic.several kinds of fresh-water fishes collected from natural water resources in khon kaen district were digested with 0.25% pepsin a to obtain the infective stage or metacercariae of fish-borne trematodes. most of them harbored at least 3 species of trematodes. two families of medical trematodes, i.e., family heterophyidae and family opisthorchiidae, were isolated. the heterophyid flukes consisted of haplorchis taichui, h. pumilio and centrocestus formosanus. opisthorchis viverrini was the only pa ...19979656383
seasonal variation of opisthorchis viverrini infection in cyprinoid fish in north-east thailand: implications for parasite control and food safety.reported is the seasonal pattern of opisthorchis viverrini metacercariae in cyprinoid fish in north-east thailand. samples of fish were collected in 1991-92 at monthly intervals from two areas-khon kaen province, where the opisthorchiasis transmission rate was high, and mahasarakham province, where the rate was low. metacercarial loads in both study areas had similar seasonal patterns. high burdens occurred in the late rainy season and winter (july to january) with low burdens during the summer ...19979185364
evaluation of bithynia funiculata snail antigens by elisa-serodiagnosis of human opisthorchiasis.four batches of crude somatic antigens from: (1) opisthorchis viverrini adult worms, (2) bithynia funiculata-whole body, (3) b. funiculata-head-foot, and (4) b. funiculata-visceral mass were assayed against sera from 81 opisthorchiasis patients, 30 parasite-free healthy individuals, and 50 individuals infected with other helminthic infections, and their antibody levels determined. by igg-elisa, the antigenic reactive proteins were found in both the head-foot and the visceral mass of b. funiculat ...19979561614
opisthorchis viverrini infection in thailand: studies on the morbidity of the infection and resolution following praziquantel treatment.a community study on opisthorchiasis was conducted in prachinburi province in eastern thailand during 1990-1992. the morbidity from opisthorchiasis in the community and reversibility of biliary pathology following treatment with praziquantel at a single dose of 40 mg/kg were assessed by longitudinal investigations of clinical, laboratory, and ultrasonographic changes. a total of 913 voluntary subjects infected with opisthorchis viverrini were randomly selected for longitudinal study, and 579 sub ...19979129534
parasites elicited cross-reacting antibodies to opisthorchis viverrini.two batches of crude antigens extracted from adult opisthorchis viverrini worms were compared. one was derived from adult worms harvested from the livers of laboratory infected hamsters and another was obtained from worms sedimented from the faeces of opisthorchiasis patients following treatment with praziquantel. sds-page and coomassie brilliant blue staining revealed that the two preparations had similar protein components of which the predominant ones were the 17-18 kda doublet. the antigens ...19979346276
prevalence of intestinal parasitic infection among children in two villages in lao pdr.the prevalence of intestinal parasitic infection among 128 children under 15 years old in two villages in khammouane province, southeastern lao pdr, was investigated. overall prevalence of helminth infection was 77.3%; the prevalence was 64.8% in children under 6 years, 88.5% in those aged 6-10 years and 81.8% in the age group above 11 years. the prevalent helminths found in the subjects were ascaris lumbricoides (48.4%), trichuris trichiura (43.8%), hookworm (37.5%) and opisthorchis viverrini ( ...19969185270
thiocyanate-independent nitrosation in humans with carcinogenic parasite infection.infection with the liver fluke, opisthorchis viverrini, is a causative agent of cholangiocarcinoma. one possible contributing factor in this carcinogenesis is the chronic, local generation of nitric oxide by inflammatory cells expressing inducible nitric oxide synthase and the production of n-nitroso compounds via the reaction between amines and nitrosating agents derived from nitric oxide. our previous studies provided evidence that nitric oxide synthesis is elevated during human liver fluke in ...19968640916
late complications of infection with opisthorchis viverrini. 19968775739
intestinal parasites among the southeast asian laborers in taiwan during 1993-1994.a large number of foreign laborers are now working in taiwan, the majority coming from southeast asia where parasitic infections are common. since 1992, monitoring the intestinal parasitic infections of these foreigners has been carried out, particularly to prevent the introduction of some of the parasites into taiwan. this paper reports results obtained during the year 1993-1994.19968803301
cross-sectional patterns of hepatobiliary abnormalities and possible precursor conditions of cholangiocarcinoma associated with opisthorchis viverrini infection in humans.the liver fluke, opisthorchis viverrini, is both highly prevalent and closely associated with cholangio-carcinoma in northeast thailand. this study measured associations between intensity of liver fluke infection and nonmalignant hepatobiliary disease diagnosed by ultrasonography among 1, 807 largely asymptomatic adult residents drawn from endemic communities. abnormalities significantly associated with intensity of infection included gallbladder enlargerment in all dimensions, presence of sludg ...19968842118
equivocal evidence of complete carcinogenicity after repeated infection of syrian hamsters with opisthorchis viverrini.the effects of repeated infection with opisthorchis viverrini on liver lesion development in male and female syrian hamsters were investigated over a 1-yr period. ten monthly intragastric applications of 50, 25, 13, or 0 parasite metacercariae resulted in pronounced proliferative and inflammatory lesions involving the first- and second-order ducts in response to the presence of adult worms. despite the development of small numbers of putative preneoplastic areas of cholangiofibrosis and morpholo ...19968864191
cholangiocarcinoma in patients with opisthorchiasis.cholangiocarcinoma is very common in areas endemic for the liver fluke opisthorchis viverrini. survival after surgical treatment of cholangiocarcinoma associated with opisthorchiasis was studied prospectively in 30 patients, all of whom resided in an endemic area. the median age was 52 (range 32-69) years and twenty-five patients were men. seven patients had their tumours removed, four with concomitant liver resection. twenty-two patients underwent palliative biliary bypass procedures to a segme ...19968869303
induction of cytochrome p450 2a6 expression in humans by the carcinogenic parasite infection, opisthorchiasis viverrini.the purpose of this study was to examine in vivo the activity of cytochrome p450 (cyp) 2a6, an enzyme capable of activating carcinogens, including n-nitrosodimethylamine, in humans with the carcinogenic liver fluke infection, opisthorchiasis viverrini, before and after treatment with the antiparasitic agent, praziquantel. coumarin hydroxylase activity of cyp 2a6 was assessed by administering a probe drug, coumarin, and measuring its metabolite, 7-hydroxycoumarin, in urines collected between 0-2 ...19968896890
opisthorchis viverrini: effect of praziquantel on the adult tegument.ultrastructural changes of the tegument of adult liver flukes, opisthorchis viverrini, after in vitro incubation in minimal essential medium containing 0, 0.1, 1.0 and 10.0 micrograms/ml of anthelminthic praziquantel for 5, 15, 30, 45 and 60 minutes were investigated by scanning (sem) and transmission (tem) electron microscopy. sem observations showed that the surface damage was composed of blebbing due to the swelling of microvilli, followed later by the disruption of these structures to form l ...19969279994
opisthorchis viverrini: the effects of colchicine and cytochalasin b on the adult tegument.the roles of the tegumental cytoskeleton were tested by treating adult flukes with colchicine and cytochalasin b. following a short incubation period (10-20 minutes), colchicine disrupted microtubules in the tegumental cells' processes which, in turn, affected the transport of dense granules from the cells' soma to the tegument; as a result some of these granules were fused together to form membrane-bound vacuoles. in addition, at many spots microtrabeculae were also depolymerized, which resulte ...19969279995
serum antibody responses in opisthorchiasis.we evaluated an enzyme-linked immunosorbent assay using crude parasite homogenates as a diagnostic test for opisthorchis viverrini infection in humans. serum antibody (ab) responses to o. viverrini adult worm homogenate (awh) and metacercaria homogenate (mh) were studied in 83 infected residents of an opisthorchiasis-endemic area in thailand. elevated levels of ab persisted for over 1 year following curative treatment with praziquantel, and cross-reactivity to o. viverrini awh and mh antigens wa ...19958550296
morphology and ultrastructure of the digestive gland of bithynia siamensis goniomphalus (prosobranchia: bithyniidae) and alterations induced by infection with the liver fluke opisthorchis viverrini (trematoda: digenea).the morphology and ultrastructure of the digestive gland of bithynia siamensis goniomphalus and its alteration by infection with opisthorchis viverrini were investigated by light and electron microscopy. the digestive gland of b. s. goniomphalus was composed of three different cell types: digestive cells, excretory cells, and narrow cells. in infected animals the number of excretory cells increased dramatically. cellular injury in digestive cells as well as in excretory cells following the infec ...19958570585
evaluation of a monoclonal antibody-based enzyme linked immunosorbent assay for the diagnosis of opisthorchis viverrini infection in an endemic area.a monoclonal antibody-based enzyme-linked immunosorbent assay (mab-elisa) was evaluated for its potential in the diagnosis of opisthorchiasis in an area endemic for opisthorchis viverrini infection. the method, based on the detection of the 89-kd o. viverrini metabolic antigen in the feces (coproantigen), was previously estimated to be sensitive enough to detect antigen excreted by a single mature fluke. in the present study, fecal specimens from 207 apparently healthy villagers in northeastern ...19957611558
morphology and ultrastructure of the redia and pre-emergent cercaria of opisthorchis viverrini (trematoda: digenea) in the intermediate host bithynia siamensis goniomphalus (prosobranchia: bithyniidae)].the intramolluscan stages of the human liver fluke opisthorchis viverrini were investigated by light, scanning, and transmission electron microscopy. the morphology of the tegument, and the excretory system of the redia and pre-emergent cercaria as well as glandular cells, tail structure, and the eye spots of the cercarial stage are described. possible environmental adaptations are discussed. the redia is characterized by a tegument which is folded concentrically and covered with densely arrange ...19957550441
opisthorchis viverrini: the tegumental cytoskeleton.the tegumental cytoskeleton of opisthorchis viverrini was observed using both conventional transmission electron microscopy and triton x-100 extraction. the cytoskeletal elements of the newly excysted juveniles, first-week and adult stages are composed of 2 components: firstly, the network of knobbed fibres designated as microtrabeculae which form the principal scaffold of the cytoplasm; and secondly, the microtubules. the microtrabeculae are more densely packed in the newly excysted juveniles a ...19957558564
serum antibody response to opisthorchis viverrini antigen as a marker for opisthorchiasis-associated cholangiocarcinoma.the liver flukes opisthorchis viverrini and clonorchis sinensis chronically infect over 30 million people in south-eastern asia, resulting in significant morbidity and a predisposition to cholangiocarcinoma (cca). liver fluke-associated cca carries a poor prognosis, partly because it is often detected at a late and advanced stage. the development of improved diagnostic methods, particularly for early cca, may improve chances of survival and cure. accordingly, we explored the use of immunological ...19947570848
increased nitrosamine and nitrate biosynthesis mediated by nitric oxide synthase induced in hamsters infected with liver fluke (opisthorchis viverrini).we previously reported that increased endogenous nitrosation in human subjects infected with the liver fluke opisthorchis viverrini in north-east thailand could be a risk factor for the development of cholangiocarcinoma. in the present study we examined our hypothesis that this increased endogenous nitrosation is mediated by nitric oxide (no) synthase induced by o. viverrini infestation. syrian golden hamsters experimentally infected with o. viverrini liver fluke excreted in the urine significan ...19947508824
liver fluke infection and cholangiocarcinoma: model of endogenous nitric oxide and extragastric nitrosation in human carcinogenesis.cancers arising during bacterial, viral and parasitic infection provide useful models to investigate the link between inflammation and carcinogenesis. because the inflammatory agent is known, relationships between immune responses, the production of dna-damaging agents, such as nitric oxide, oxygen radicles and n-nitroso compounds, and cancer risk can be explored. this paper first describes the close relationship between infection with the liver fluke, opisthorchis viverrini, and cholangiocarcin ...19947510035
possible protective immunity in human opisthorchiasis.chronic infections with the liver flukes opisthorchis viverrini and clonorchis sinensis affect over 30 million people in southeastern asia. with ongoing exposure, reinfection readily occurs following curative treatment and cumulative infections result in significant morbidity and a predisposition to cholangiocarcinoma. though protective immunity has never been described in human opisthorchiasis, heterogeneity in worm burden occurs and a small number of exposed residents of endemic areas remain a ...19947526321
[cholangiolar carcinoma].cholangiocarcinoma affects both sexes equally, is more prevalent in individuals age 50 to 70. associations with many other diseases are known, in particular with primary sclerosing cholangitis, ulcerative colitis and parasitic infestation (clonorchis sinensis, opisthorchis viverrini). about 95% are histopathologically classified as adenocarcinoma. the localisation of the tumor determines clinical course and prognosis. if the tumor is located above the hepatic duct bifurcation, only one side of t ...19947531268
infection with liver flukes (opisthorchis viverrini, opisthorchis felineus and clonorchis sinensis). 19947715069
changes in serum antibodies to opisthorchis viverrini in humans and hamsters following treatment of opisthorchiasis. 19947872997
association of liver fluke (opisthorchis viverrini) infestation with increased expression of cytochrome p450 and carcinogen metabolism in male hamster liver.synergy between exposure to chemical carcinogens (nitrosamines) and infestation with the liver fluke opisthorchis viverrini has been demonstrated in a hamster model of hepatocarcinogenesis (flavell et al., carcinogenesis 4:927-930, 1983; thamavit et al., carcinogenesis 8:1351-1353, 1987). to elucidate the mechanisms of this interaction we tested the hypothesis that liver parasitism might influence the expression and activity of carcinogen metabolizing enzymes. we found that one, and perhaps more ...19947916996
opisthorchis viverrini: ultrastructure of the tegument of the first-week juveniles and adult flukes.the tegument of one-week-old and adult flukes of opisthorchis viverrini were studied by transmission electron microscopy. the tegument of both stages is composed of a syncytium formed by processes of the tegumental cells lying underneath the outer-circular and the inner-longitudinal muscle layers. the tegument is bounded by trilaminate outer and inner membranes; the former is coated with a thin glycocalyx, while the latter has short basal infoldings. there are 4 forms of tegumental granules, nam ...19947928062
multi-infection with helminths in adults from northeast thailand as determined by post-treatment fecal examination of adult worms.six hundred and eighty-one residents from 16 provinces in northeast thailand who had previously been found positive for opisthorchis viverrini and taenia spp. eggs were given 40 mg praziquantel (bayer, germany), per kg body weight. the total stool output for one to three days was collected and examined for adult worms. the prevalence of o. viverrini in this group was 92.4%. the intestinal flukes echinostoma malayanum, e. ilocanum and e. revolutum were found to be high in males, with 8.3%, 8.1% a ...19947939164
association of antibodies to opisthorchis viverrini with hepatobiliary disease in northeastern thailand.the association between opisthorchis viverrini infection and hepatobiliary disease was studied in northeastern thailand. positive rates of o. viverrini infection and antibody titers to o. viverrini adult worm extracts, which were determined by enzyme-linked immunosorbent assay (elisa), were compared among four groups: thai patients with cholangiocarcinomas (chca), those with calculus cholecystitis (cclt), endemic area victims of traffic accidents, and japanese individuals used as negative contro ...19947943568
cross-sectional study of opisthorchis viverrini infection and cholangiocarcinoma in communities within a high-risk area in northeast thailand.we describe an innovative strategy to quantify risk of cancer associated with varying levels of exposure to chronic parasitic infection through the identification of asymptomatic cases of cholangiocarcinoma within a population-based survey of opisthorchis viverrini infection. stool samples from 12,311 adults over age 24 years from 85 villages in northeast thailand were examined for intensity of liver fluke infection. people from varying egg count categories were selected for ultrasound examinati ...19947960220
parasite-associated morbidity: liver fluke infection and bile duct cancer in northeast thailand.infection with the liver fluke, opisthorchis viverrini, remains a major public health problem in northeast thailand, where approximately one-third of the population is infected. the northeast region is largely populated by laos-descendent thais who enjoy eating raw fish, which harbour the infective stage of the fluke. the parasite has maintained its presence in the population despite the widespread use of praziquantel and dissemination of health education material throughout the region by vigoro ...19947982745
opisthorchis viverrini infection in thailand: symptoms and signs of infection--a population-based study.a population-based study of the clinical, laboratory and ultrasonographic findings in patients suffering from mild or moderate opisthorchiasis in prachinburi province, thailand was conducted in 1990-1992. the effectiveness of treatment with praziquantel at 40 mg/kg body weight was evaluated. after treatment, a long-lasting, marked improvement in the well-being of the study group was observed. symptoms common in opisthorchiasis infection decreased in intensity and the clinical response showed tot ...19947992340
[prevalence of intestinal parasites among thais in israel].stool samples from 93 thais working in israel were examined for the presence of parasites. the overall prevalence of infection by 1 or more species was 74%. opisthorchis viverrini and hookworm were the most prevalent parasites (51.6% and 44.1%, respectively). they were also the parasites most frequently found in mixed infections; about a quarter of the workers were infected with both. other helminths found in only a few cases were: fasciolopsis buski (3 cases), taenia sp. (3), paragonimus sp. (1 ...19948034263
opisthorchiasis control in northeast thailand: proposal for a new approach.opisthorchiasis, i.e. infection with the liver fluke opisthorchis viverrini is an important health problem in thailand and adjacent laos, and its control is therefore of high priority. pilot projects have shown that after praziquantel treatment high re-infection rates occurred within a short period of time. to reduce re-infections it is proposed to couple the time of treatment to the seasonal transmission dynamics and thus treat the population in march when risk of infection for the snail and fi ...19948087151
strong promoting effect of opisthorchis viverrini infection on dimethylnitrosamine-initiated hamster liver.continuous administration of dimethylnitrosamine (dmn) to syrian hamsters infected with the liver fluke, opisthorchis viverrini (ov) results in a 100% incidence of cholangiocellular carcinomas. in a two-stage experiment, however, dosing with liver flukes caused only a few lesions to develop (flavel, d.j. and lucus, s.b. (1983) carcinogenesis, 4, 927]. to clarify this anomaly, syrian hamsters were initiated with 20 mg/kg dmn injected i.p. 19 days prior to 80 ov metacercaria infection. at 45 weeks ...19948180954
identification and potential use of a soluble tumor antigen for the detection of liver-fluke-associated cholangiocarcinoma induced in a hamster model.a liver-fluke-associated cholangiocarcinoma (cca), comparable to that occurring in humans, was induced by exposing opisthorchis viverrini-infected hamsters to dimethylnitrosamine (dmn). tumor masses were removed and histopathologically identified, then one portion was extracted for antigens used in the production of monoclonal antibodies (mabs). the remaining portions were used to establish cca cell lines. the antigens produced and secreted by these cell lines, as well as those originally presen ...19948194877
promotion of cholangiocarcinogenesis in the hamster liver by bile duct ligation after dimethylnitrosamine initiation.administration of hepatocarcinogenic nitrosamines before or after infection with the liver fluke, opisthorchis viverrini (ov), results in marked development of cholangiocellular and hepatocellular precancerous and cancerous lesions in the hamster liver. the promoting effects of ov are believed to be exerted either mechanically, chemically or immunologically. to test the influence of possible mechanical effects, syrian hamsters were initiated with a single i.p. injection of dimethylnitrosamine (d ...19938242874
trematode infections. opisthorchiasis, clonorchiasis, fascioliasis, and paragonimiasis.the parasitic diseases of the liver and lung are caused by trematodes or flukes--opisthorchis viverrini, o. felineus, fasciola hepatica, and paragonimus westermani. humans get infected by eating the second intermediate host of the fluke, for example, fish, crab, or water plant. the disease runs a chronic course. the diagnosis is made by the recover of eggs in stools or sputum, or by serodiagnosis. praziquantel is the drug of choice except in falcioliaisis.19938254167
cholangiocarcinoma: epidemiology, mechanisms of carcinogenesis and prevention.cholangiocarcinoma is a relatively rare cancer; worldwide it accounts for an estimated 15% of liver cancers. in most areas, the etiology is rather obscure, and identified risk factors such as hepatolithiasis, inflammatory bowel disease, and exposure to thorotrast can account for only a small proportion of cases. in certain areas of southeast and eastern asia, however, incidence rates are very high, and here there is a strong association with infection with the liver flukes clonorchis sinensis an ...19938268770
opisthorchis viverrini: changes of the tegumental surface in newly excysted juvenile, first-week and adult flukes.the tegumental surface of the newly excysted juvenile, first-week and adult stages of a human liver fluke, opisthorchis viverrini, was studied by scanning electron microscopy. the surface of the newly excysted juvenile is characterized by circumferentially arranged ridges alternated with troughs which bear rows of spines encircling the body. these spines are characterized by the shapes of their edges: the first type with serrated edge appears on the anterior part, and the second type with single ...19938314365
reversal of biliary tract abnormalities associated with opisthorchis viverrini infection following praziquantel treatment.we recently demonstrated a number of biliary tract abnormalities associated with moderate to heavy opisthorchis viverrini infection among 95 selected village residents in north-east thailand, who were treated with praziquantel immediately after initial examination and re-examined by abdominal ultrasonography 10 months later. dramatic improvement in the gall-bladder status of previously infected individuals was observed, including reduction of gall-bladder length and width and regained contractib ...19938337727
imported opisthorchis viverrini and parasite infections from thai labourers in taiwan.in order to determine the prevalence of intestinal parasites among labourers from thailand in taiwan, the stool samples from 1364 thai labourers were examined by the formalin-ether concentration method and 18.0% were found to be infected with one or more parasites. the infection rates of hookworm, opisthorchis viverrini, strongyloides stercoralis, enterobius vermicularis, ascaris lumbricoides, hymenolepis nana, capillaria philippinensis, schistosoma japonicum, echinostoma sp., entamoeba coli, gi ...19938354853
precancerous lesions of the biliary tree.malignant tumors may arise from any portion of the biliary tree. the term cholangiocarcinoma (cc) applies to both intra- and extrahepatic tumors. more than 95% of these tumors are adenocarcinomas. differentiation between cc and metastatic adenocarcinoma represents a difficult task for the pathologist. the presence of an intratumoral mini-ductal plate, and in situ carcinoma in bile ducts near the tumor and modulation from the bile duct towards parenchymal liver cells represent the major criteria ...19938389160
ultrastructural hepatic alterations in hamsters and jirds after experimental infection with the liver fluke opisthorchis viverrini.changes in the hepatocytes of male hamsters (mesocricetus auratus) and jirds (meriones unguiculatus) at 220 days after experimental infection with the liver fluke opisthorchis viverrini were studied by light and electron microscopy. the hepatocytes of the control group were characterized by an intracellular compartmentation. a globular nucleus was located centrally. the main features of the perinuclear zone were the cisternae of the rough endoplasmic reticulum (rer) and interjacent mitochondria, ...19938415540
time-dependent modulation of liver lesion development in opisthorchis-infected syrian hamster by an antihelminthic drug, praziquantel.in the north-east of thailand, repeated antihelminthic therapy has been introduced for control of the opisthorchiasis known to be a major risk factor for cholangiocellular carcinomas. what influence this may have on tumorigenesis, however, remains unclear. the effects of administration of praziquantel, an antihelminthic drug, at different time points subsequent to infection with opisthorchis viverrini (ov) on 2,2'-dihydroxy-di-n-propylnitrosamine (dhpn)-initiated lesion development in the liver ...19938463130
field trials in the control of opisthorchis viverrini with an integrated programme in endemic areas of northeast thailand.a control programme of opisthorchiasis was carried out for three years in three villages of northeast thailand in order to compare the effectiveness of two intervention measures. the intervention measures employed were to give praziquantel treatment to all infected people either once (village i) or twice (village ii) per year with the integration of regular health education and sanitation improvement. a control village (village iii) received no intervention during the study. sampling of the popu ...19938488064
studies on lophocercous cercariae from bithynia siamensis goniomphalus (prosobranchia: bithyniidae).cercariae from bithynia siamensis goniomphalus were studied in an area endemic for opisthorchiasis. snails emitted different types of cercariae when shedding was induced by illumination. in addition to two lophocercous cercariae, a monostome cercaria (probably notocotylus sp), two different furcocercariae and a xiphidiocercaria were found. two similar types of lophocercous cercariae were distinguishable and one could be identified as opisthorchis viverrini. to date the cercaria of o. viverrini h ...19937939943
pharmacokinetics of praziquantel in patients with opisthorchiasis.the pharmacokinetics of praziquantel was investigated in 9 thai male patients with asymptomatic opisthorchiasis (stool positive) and 9 patients (6 males, 3 females) with moderately advanced infection (hepatomegaly). the geometric means of the pretreatment opisthorchis viverrini egg count in these patients were 2,950 vs 4,468 eggs per gram of stool. the results indicate the impairment of metabolism of praziquantel in the moderately advanced stage opisthorchiasis. the pharmacokinetics of the drug ...19937939947
opisthorchis viverrini and cholangiocarcinoma in northeast thailand.population-based research is beginning to show clearly the devastating impact that opisthorchis viverrini infection has on the laos-descendent population of northeast thailand who love to eat uncooked meat and fish, one of which being the parasite's intermediate host: cyprinoid fish. here, melissa haswell-elkins, paiboon sithithaworn and david elkins discuss the parasite's life cycle and epidemiology, highlighting the close relationship between this infection and bile duct carcinoma, which is a ...199215463578
specific and cross-reactive monoclonal antibodies to the 89-kda antigen of opisthorchis viverrini. 19921283231
larval stages of medically important flukes (trematoda) from vientiane province, laos. part ii. cercariae.the cercariae of five flukes, which are potential human parasites, opisthorchis viverrini (family opisthorchiidae), haplorchis taichui (heterophyidae), schistosoma spindale (schistosomatidae), fasciolopsis buski, and fasciola gigantica (fasciolidae) were found in freshwater snails from laos. the cercariae of the above species, recorded in laos for the first time, are illustrated and their morphology is briefly described. the snail helicorbis umbilicalis represents a new intermediate host of f. b ...19921290378
study on the surface morphology of the developmental stages of the liver fluke, opisthorchis viverrini (trematoda: opisthorchiidae).the external morphology of some developmental stages of the fluke opisthorchis viverrini (trematoda: opisthorchiidae), parasitizing humans in southeast asia was studied for the first time using electron microscopy. the surface structure of the egg, as well as the rediae, cercaria, metacercaria, and adult found in naturally infected hosts from laos are described herein and their morphological characteristics discussed.19921290379
relationship between intensity of opisthorchis viverrini infection and hepatobiliary disease detected by ultrasonography.twenty-four locality-, age- and sex-matched groups of village residents with no light, moderate and heavy opisthorchis viverrini infection were examined by ultrasonography. highly significant differences were observed between the groups in the relative size of the left lobe of the liver and the fasting and post-meal size of the gall-bladder. in addition, indistinct gall-bladder wall, the presence of gall-bladder sludge and strongly enhanced portal vein radicle echoes were most frequently observe ...19921311966
opisthorchis viverrini infection in northeast thailand and its relationship to cholangiocarcinoma. 19921327263
histomorphological characteristics of cholangiocellular carcinomas in northeast thailand, where a region infection with the liver fluke, opisthorchis viverrini is endemic.northeast thailand has a very high incidence rate of intrahepatic biliary tumors which is believed to closely related to infestation with the liver fluke, opisthorchis viverrini. this study was conducted to ascertain whether there are any phenotypic differences in such tumors between northeast thailand and japan, a country free of liver flukes. forty one intrahepatic cholangiocarcinomas from patients in northeast thailand were histopathologically compared with 39 lesions collected in japan. the ...19921334615
cholangiocarcinomas in japanese and thai patients: difference in etiology and incidence of point mutation of the c-ki-ras proto-oncogene.point-mutational activation of the c-ki-ras proto-oncogene has been shown to be rare in human hepatocellular carcinoma, the most common primary liver cancer and one usually associated with chronic viral infection. to reveal the association of c-ki-ras activation with cholangiocarcinogenesis under different etiological backgrounds, the incidence of point mutation at codons 12 and 13 of the c-ki-ras proto-oncogene was examined in three groups of human liver cancers with differentiation to biliary ...19921336666
prevalence and intensity of opisthorchis viverrini in rural community near the mekong river on the thai-laos border in northeast thailand.the prevalence and intensity of opisthorchis viverrini in fourteen villages in nakhon-phanom province, northeast, thailand have been investigated. overall prevalence of o. viverrini infection was 66.4 per cent in a total population of 2,412 individuals. the prevalence was 18.5 per cent in children under 5 years, 38.9 per cent in those aged 5-9 years, and ranged from 64.9 per cent to 82.2 per cent in the age group above 10 years. the intensity of o. viverrini infection increased with age. the mea ...19921402447
development of immune-complex glomerulonephritis and amyloidosis in syrian golden hamsters infected with opisthorchis viverrini.renal disease associated with opisthorchis viverrini infection was investigated in syrian golden hamsters. on the fourth week after infection with 100 viable metacercariae; anti-tegumental membrane antibodies were detected in the sera by immunofluorescence antibody technic and by enzyme-linked immunosorbent assay. six weeks after infection tegumental and anti-tegumental membrane immune-complex and amyloid fibrils were found in the glomeruli. amyloid was characterized to be aa protein. acute prol ...19921402485
malacological survey in the sirikit reservoir, the largest earthfilled dam in thailand.ten species of freshwater molluscs were found in a malacological survey in the sirikit reservoir in 1985. among these species, tricula aperta or neotricula aperta, intermediate host of human schistosomes, bithynia (digoniostoma) siamensis goniomphalos and b. (d.) funiculata, the first intermediate host of opisthorchis viverrini were not found. it is revealed that most of the habitats in the sirikit reservoir are not suitable for the survival and colonization of molluscs. thus few species of edib ...19921439988
control of opisthorchis viverrini cercariae using the copepod mesocyclops leuckarti. 19921439992
cloning and characterization of ribosomal rna genes from opisthorchis viverrini.the ribosomal dna (rdna) unit of the liver fluke opisthorchis viverrini has been cloned and characterized. the results demonstrated that the total length of this unit is approximately 13 kb, containing 4.2 kb of large subunit (lsu) rdna, 2.0 kb of small subunit (ssu) rdna, 1.0 kb of transcribed spacer dna and 5.8 kb of non-transcribed + external transcribed spacer dna. examination of the non-transcribed spacer region between different rdna units showed variation in the restriction sites rather t ...19921594296
separation and characterization of adult worm proteins and glycoproteins from the liver fluke opisthorchis viverrini.detailed studies of liver fluke proteins and antigens are necessary to facilitate further investigation of the human immune responses to these parasites. accordingly, opisthorchis viverrini antigens were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) and immunoblotting. we initially encountered excessive background smearing, vertical streaking, and indistinct bands that were similar to problems previously described by investigators studying this and other tremat ...19921635026
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