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At least 1,369 records · Page 76Linked to original sources
PubMed1987

Hymenolepis citelli, H. diminuta and H. microstoma: immunoglobulin-containing cells in the lamina propria of the mouse gut during primary and secondary infections.

The indirect immunofluorescent technique was used to determine the occurrence of IgA, IgM and IgG1 immunoglobulin-containing cells in local intestinal mucosal immune responses to Hymenolepis citelli, H. diminuta and H. microstoma infections in mice. In the intestinal lamina propria of H. citelli and H. diminuta infected mice there was no increase in the mean numbers of immunoglobulin-containing cells when compared with uninfected control mice, but there was in H. microstoma infected mice. The numbers of IgG1- positive cells in both infected and uninfected mice were very small relative to IgA and IgM immunocytes. The distribution of immunocytes in the lamina propria of infected and uninfected mice was essentially similar and the localization of isotypes in duodenal sections showed no immunoglobulins in the villous epithelial cells. There was also no marked difference between primary and secondary infections indicating that immunoglobulin-containing cells play no major role in functional immunity against hymenolepid infections in the mouse. The presence of IgA and IgM was also demonstrated on the tegument of the tapeworms, although the distribution was patchy and more abundant on H. microstoma than on H. diminuta or H. citelli. The time of appearance of both isotypes was latest on H. citelli.

Animals↗
PubMed1993

Development of Proteocephalus torulosus in the intermediate host under experimental conditions.

The development of the tapeworm Proteocephalus torulosus (Batsch, 1786) (Cestoda: Proteocephalidae), a parasite of cyprinid fish, was studied in the intermediate host under experimental conditions. The eggs of P. torulosus were typified by a relatively small outer envelope (hyaline membrane) and a thick middle layer surrounding the oncosphere. Incubation of P. torulosus eggs at different temperatures revealed the ability of some oncospheres to survive and remain infective to the intermediate host for up to 5 weeks at 5-7 degrees C, 12 days at 10-12 degrees C, and 8 days at 20-22 degrees C. Of 8 copepod species used in these experiments, complete development of larvae was observed only in Cyclops strenuus. Growth was completed in 9-12 days at 20-22 degrees C and four weeks at 9-10 degrees C. During development the cercomer was not observed. The infectivity of larvae from C. strenuus for the definitive hosts, cyprinid fish, was very low and only one chub of 26 fish used for feeding experiments (21 chub, Leuciscus cephalus, 3 bleak, Alburnoides bipunctatus, 1 rudd, Scardinius erythrophthalmus--all the family Cyprinidae, and 1 loach, Noemacheilus barbatulus--the family Cobitidae) became infected.

Animals↗
PubMed1992

A hidden break in the 28.0S rRNA from Diphyllobothrium dendriticum.

Nondenatured and denatured total RNA from the tapeworm Diphyllobothrium dendriticum (Cestoda) was analysed by agarose gel electrophoresis. It was found that the large subunit ribosomal RNA (lrRNA) is 28.0S and the small subunit ribosomal RNA (srRNA) is 19.5S. Following denaturation the 28.0S rRNA was disrupted into a 19.5S subfragment and a 20.7S subfragment due to the presence of a centrally located hidden break. By hybridization of Northern blot membranes with oligonucleotide probes specific for the 5'- and 3'-ends of the lrRNA respectively, we have shown that the 19.5S subfragment is from the 5'-end (the alpha-subfragment) and the 20.7S subfragment from the 3'-end (the beta-subfragment) of the 28.0S rRNA of D. dendriticum.

Animals↗
PubMed1998

Ecology of proteocephalus torulosus in the blue bream (Abramis ballerus) fromthe oder river on the borders of germany and poland

During studies on the ecology of fish helminths, the tapeworm Proteocephalus torulosus (Batsch, 1786) was frequently found in the intestine of the blue bream (Abramis ballerus) from the Oder River (Germany/Poland). In total, 633 fish, ranging between two and 16 years old, were sampled at monthly intervals over a two year period during 1993-1995. Statistically significant differences in the seasonal occurrence of the parasite in its fish host were observed. In 1993, the prevalence remained at a high level, ranging between 61. 9 and 100%. During the summer of 1994, this value decreased to 5.5% and remained low for the rest of the year. The pattern of mean intensity of infection was similar to that of the prevalence. In 1993, the mean intensity varied between 8.4 and 31.8 worms per infected fish, with a continual loss of worms being observed in the summer of 1994. Changes in the amount of suspended particulate matter in water have been identified as the main cause of these observed differences in the course of infection of blue bream.

Journal Article↗
PubMed1998

Parasites in paradise: patterns of helminth distribution in hawaiian stream fishes

Of the 13 species of helminths that parasitize stream fishes in Hawai'i, seven species are considered to be native to the archipelago and the remaining six species to be introduced by man. Sources of colonization for native species are piscivorous birds for three species, and marine fishes for four species. Non-native helminths have been brought to Hawai'i in association with the importation of parasitized exotic species of poeciliids introduced into streams for mosquito control and as aquarium releases. Many of these introduced parasites have broad host specificity and now infect the five species of native gobioid stream fishes. Exotic parasites, including a roundworm Camallanus cotti, a tapeworm Bothriocephalus acheilognathi and a leech Myzobdella lugubris, are more widely distributed among Hawaiian streams than are native species.

Journal Article↗
PubMed1986

Immunological aspects in the rejection process of Hymenolepis muris-sylvaticae from CFLP and NMRI mice.

When mice were treated with 1.25 mg cortisone acetate thrice weekly, recovery of Hymenolepis muris-sylvaticae was significantly higher than in untreated controls, both in oral infections with six cysticercoids and surgical transplantations of one 7-day or 8-day-old worm. Cortisone treatment also resulted in the worms being located more anteriorly in the small intestine. Evidence of an immunological response against the tapeworm in the intestine is given by: an accelerated rejection of a secondary oral cysticercoid infection and a significant difference of the dry weights of the worms recovered on day 10 in CFLP mice; an accelerated rejection of a secondary surgical infection on days 4 and 6 in CFLP mice and on days 3 and 4 in NMRI mice; an accelerated rejection of a secondary surgical infection given 3 and 6 months after the primary immunizing infection in SWISS-albino mice.

Animals↗
PubMed1984

Scanning electron microscope studies of the mucosa of rats infected with Hymenolepis diminuta (Cestoda).

The intestinal morphology of rats given one, 10 or 100 cysticercoids of hymenolepis diminuta was examined by scanning electron microscopy. The presence of this tapeworm causes extensive villous atrophy and fusion. The most extreme changes in mucosal architecture were observed adjacent to the mature proglottides of the worm and in these areas the villi were reduced either to flattened plate-like structures or to low irregularly shaped undulations. The presence of one large H. diminuta resulted in more severe pathological damage than caused by several smaller worms. Colonization of the upper region of the ileum by long filamentous bacteria was also observed in rats infected with H. diminuta.

Animals↗
PubMed1996

Hydatid cyst of the pterygopalatine-infratemporal fossa.

Hydatid disease is caused by the parasitic tapeworm. Echinococcus. This parasite in larval stage can thrive in many parts of the body, most commonly in the liver and the lung. Hydatid disease in the head and neck region is rare. An unusual location for hydatid disease in the pterygopalatine fossa-infratemporal fossa is presented. The patient did not have evidence of any other cyst on a ten-year follow-up.

Adult↗
PubMed2006

A rare case of nasal cysticercosis mimicking a nasal dermoid.

Cysticercosis, caused by infestation with the pork tapeworm Taenia solium, is known to commonly involve the brain, muscles and subcutaneous tissue. Diagnosing cysticercosis can be difficult as its clinical presentation is usually non-specific. When involving subcutaneous tissue, it can present as firm, non-tender, solitary or multiple nodules. We report a case of subcutaneous cysticercosis at the nasion mimicking a nasal dermoid.

Child↗
PubMed2000

Mode of action of cyclosporin A against Hymenolepis microstoma (Cestoda): relationship between cyclophilin binding and drug-induced damage.

Cyclosporin A (CsA) is a widely investigated experimental anti-parasitic drug whose mode of action remains unresolved. The immunosuppressive action of CsA depends on the drug binding to the intracellular receptor cyclophilin (CyP). This study investigates whether complexing of CsA with parasite CyP is equally essential for its anthelmintic action. The correlation between initial cyclosporin-induced damage in vitro and drug binding to parasite CyP has been examined. CsA and the analogues B-5-49, CsH and CsA-acetate all induced similar damage to the tapeworm Hymenolepis microstoma in vitro in incubations between 2 h and 4 days. The initial foci of drug damage were the parasite surface and mitochondria in the syncytium. In a competitive binding assay only B-5-49 displaced [H3]-CsA from either crude parasite cytosolic CyP or affinity-purified CyP while CsH and CsA-acetate had no effect. These data suggest strongly that cyclosporins act on the surfaces of helminth parasites but that drug action does not involve complex formation with CyP. An alternative drug-binding site must therefore be identified which may lead to the rational design of novel anthelminitic drugs.

Animals↗
PubMed1975

Some influences of population density on Hymenolepis diminuta in rats.

When measured 56 days postinfection the length, wet weight and dry weight of Hymenolepis diminuta were all found to decrease with increasing number of cysticercoids given up to 20. The mean position of the worms in 10, 12 and 20 worm infections is significantly posterior to that of 1, 2 and 5 worm infections and the worms are attached over a wider area of the intestine. Egg production by the worms was followed up to day 56 postinfection; the number of eggs produced per worm and even per rat decreased with increasing population density. Thus the best way to get most eggs and to maintain the parasite in the laboratory is to have rats infected with only one tapeworm. Rats given 1-20 cysticercoids showed a mean recovery of 100-65%, while rats given 40-200 cysticercoids showed a mean recovery ranging from 13 to 2%. In addition to 'normal' worms, defined as worms greater than 10 mm, small, most probably destrobilated, worms were found. In the 50 and 100 cysticercoid infections, worm recoveries were, respectively, 8% 'normal', 16% small, and 2% 'normal', 5% small. From the significantly lower recovery from heavy infections it is concluded that a deleterious factor is operating during the 8 weeks after the infection.

Animals↗
PubMed1983

Parthenogenesis and asexual multiplication among parasitic platyhelminths.

Among flatworms with parasitic and commensal modes of existence, parthenogenesis and asexual multiplication appear to be largely confined to the Digenea and Cestoda, the only parasitic platyhelminths that routinely utilize indirect life-cycles. Parthenogenesis is apparently restricted to a minority of adult digeneans and cestodes inhabiting their final hosts, and a survey is made of the particular modes of parthenogenesis (i.e. apomictic, automictic and generative) which are employed by such adults. Asexual (amictic) multiplication, in the form of fissioning, is demonstrated by young adults of the cyclophyllidean cestode, Mesocestoides corti, but is otherwise not exhibited by adult cestodes or digeneans, other than in the perplexing phenomenon of proglottid formation in polyzoic tapeworms. Secondary multiplication is of ubiquitous occurrence in digenean life-cycles in the form of the proliferation which takes place within sporocysts and rediae (germinal sacs) located in the first intermediate host. The controversy concerning the nature of this multiplication is reconsidered in the context of recent findings which have centred on cellular aspects. On the basis of present evidence germinal sac multiplication should be regarded as an asexual rather than a parthenogenetic process. The cestode asexual multiplication which occurs in intermediate hosts is a function of the metacestode stage of development. Metacestode proliferation is only known from about 20 species and 6 families of polyzoic cestodes with approximately half the described instances occurring in the family Taeniidae. The organization of these proliferative metacestodes, findings concerning their totipotent stem cells and the ontogeny of buds and new scolices are all reviewed. Finally, the capacity for population expansion of multiplicative larval digeneans and metacestodes are compared, while the ecological roles and the genetical consequences of both parthenogenesis and amictic multiplication in the two taxa are also examined.

Animals↗
PubMed1976

Transplantation of Hymenolepis diminuta into naive, immune and irradiated mice.

Almost 100% of 7- to 10-day-old Hymenolepis diminuta became established when surgically transplanted from donor mice into the duodenum of naive recipient mice. Transplanted tapeworms survived 8-12 days, by which time they had survived much longer in total than they would have done in the donor. Mice previously immunized by a primary infection rejected transplants within 4 days. Sub-lethal irradiation (550 rad) delayed rejection by immune mice but such mice still rejected worms much more quickly than did naive mice. Surgery was shown to delay by 2-3 days the rejection of worms by naive mice, and the importance of circumventing surgery by administering the worms per os is emphasized. Prospects for reconstituting irradiated immune mice are considered vis-à-vis work with nematodes, and the differences which, on present knowledge, appear to exist between nematode and cestode rejection are briefly discussed.

Animals↗
PubMed1983

Allosteric control of pyrimidine transport in Hymenolepis diminuta: an unusual kinetic isotope effect.

A thymine-uracil transport system is present in the plasma membrane brush-border of the tapeworm, Hymenolepis diminuta. The relation between initial uptake and substrate concentration of either thymine or uracil was sigmoidal when 2-14C-labelled substrates were used. In contrast, absorption kinetics of methyl-14C- and 3H-labelled substrates were hyperbolic. Since there was no metabolism of the labelled substrates during the incubation period, these differences indicate that the sigmoidal kinetics of pyrimidine transport in this organism is an isotopic effect associated with the presence of the 14C label at the 2 position in the pyrimidine ring.

Animals↗
PubMed1987

Population dynamics in echinococcosis and cysticercosis: evaluation of the biological parameters of Taenia hydatigena and T. ovis and comparison with those of Echinococcus granulosus.

An evaluation has been made of the biological and epidemiological parameters that determine the basic reproductive rates of Taenia hydatigena and T. ovis. These host-parasite systems are characterized by (i) no overcrowding in either host; (ii) no parasite-induced mortality of either host; (iii) no density-dependent constraint in the definitive host, but a strong, rapidly mobilized, short-acting immunity in the intermediate host and (iv) egg production which, in the natural environment, is high enough to prevent superinfection. It is considered that tapeworms with these characteristics are more stable to fluctuations in environmental conditions and to control measures such as dog dosing, than species which have a low egg production and infectivity such as Echinococcus granulosus. Reciprocal immunity exists between T. hydatigena and T. ovis in sheep. Exposure to T. hydatigena suppresses infection by T. ovis, but not by E. granulosus. This has important epidemiological consequences where these parasites co-exist.

Animals↗
PubMed1984

Migrational responses of Hymenolepis diminuta to surgical alteration of gastro-intestinal secretions.

The effects of the direction of gut flow, of injections of glucose and saline into different regions of the small intestine and of surgical re-routing or ligature of gastric, biliary and pancreatic secretions into the small intestine have been correlated with changes in the migratory response of the rat tapeworm Hymenolepis diminuta. Reversing the normal anterior to distal flow of luminal contents in the small intestine did not affect worm migration following feeding. Injections of a glucose-saline solution into the duodenum did not initiate a migratory response; similar injections into the mid- and posterior regions of the small intestine resulted in migrational responses similar to those following intragastric glucose feeding. Re-routing gastric secretions to the distal duodenum inhibited anterior migration of the worms beyond the new point of entry of gastric juices. Results following re-routing and ligation of the biliary and pancreatic secretions suggest that there is a potent cue to anteriad migration in the pancreatic secretions. Biliary secretions also appear to contain an additional migratory cue to worm migration. In order of importance the factors stimulating/inhibiting worm migration are pancreatic greater than gastric greater than biliary greater than glucose. The results support the hypothesis that the factors affecting worm distribution in the small intestine are interactive and synergistic, involve other luminal factors, such as 5-hydroxytryptamine and the physico-chemical gradients, and are of a regional nature such that the migratory response of a particular worm is directly related to its position in the small intestine when the cues to relocation are received.

Animals↗
PubMed1980

Membrane transport of aromatic amino acids by Hymenolepis diminuta (Cestoda).

Aromatic amino acids (phenylalanine, tryptophan and tyrosine) are absorbed by Hymenolepis diminuta through a combination of mediated (non-Na+-sensitive) transport and diffusion. All 3 amino acids are accumulated against an apparent concentration difference during a 30-min incubation of tapeworms in 0.1 mM 3H-labelled amino acid. Inhibitor studies demonstrate that phenylalanine, tryptophan and tyrosine are mutually competitive inhibitors of the uptake of each other, and the uptake of these amino acids is inhibited by aliphatic amino acids but not by basic or dicarboxylic amino acids. The D- and L-isomers of aromatic amino acids are equally effective in inhibiting aromatic amino acid uptake. The data indicate that at least 3 amino acid transport loci are involved in aromatic amino acid transport by H. diminuta.

Amino Acids↗