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At least 433 records · Page 24Linked to original sources
PubMed1977

Studies on the embryogenesis of the tapeworm Shipleya inermis Fuhrmann, 1908 using transmission and scanning electron microscopy.

Scanning electron micrographs (SEM) are shown of the scolex, microtrichs, and the submucosal capsule formed by the worm. The course of development of the outer capsule and the outer envelope from the early preoncosphere to the mature oncosphere is followed by SEM and (in part) transmission electron microscopy. Three phases of development of the outer envelope (OE) were noted: (1) early preoncosphere with OE with a relative smooth outer surface, (2) the development of surface lamellae and (3) the formation of a dendritic area distal to the lamellae; all of the organelles appear to be secretory. Stereoscopic pairs of cryofractured developmental stages are used to aid understanding of the OE. Transmission electron micrographs are used to corroborate the SEM micrographs.

Cestoda↗
PubMed1975

A comparative study of the two alternative larval forms of Hymenolepis nana, the dwarf tapeworm, with special reference to the process of excystment.

Studies of the cysticercoids of Hymenolepis nana from insects and from mouse villi revealed important differences in cyst structure and function. The insect form resists low pH unless treated with bile salts which render the cyst permeable and reduce infectivity to mice. Bile salts are not essential for scolex activation. Activation is inhibited by pH 2.5 and under and by 1% succinic acid up to pH 4.0. The importance of scolex immobility and energy conservation in relation to cyst impermeability is discussed. The villus cysticercoid has no special insulating layer. It is vulnerable to low pH and cannot infect mice orally. Bile salts are without effect and excystment occurs unaided by external agents. The structural differences between the two forms revealed by the electron microscope may be attributed to changes in the relative rates of development of the various tissues.

Animals↗
PubMed1988

Immunocytochemical demonstration of 5-hydroxytryptamine (serotonin) and vertebrate neuropeptides in the nervous system of excysted cysticercoid larvae of the rat tapeworm, Hymenolepis diminuta (Cestoda, Cyclophyllidea).

The localisation and distribution of 5-hydroxytryptamine (5-HT, or serotonin) and a number of vertebrate neuropeptides in the nervous system of excysted (0-24 h) cysticercoid larvae of Hymenolepis diminuta were determined by an indirect immunofluorescence technique in whole-mount preparations. In the central nervous system, cell bodies and nerve fibres immunoreactive to 5-HT are present in the main commissure, lateral and rostellar ganglia, and the longitudinal nerve cords and their connectives. In the peripheral nervous system, immunoreactive nerve fibres occur in a poorly developed nerve plexus within each sucker. Among the vertebrate peptides tested, antisera to pancreatic polypeptide (PP), polypeptide YY (PYY), peptide histidine isoleucine (PHI) and gastrin-releasing peptide (GRP) gave positive results. Immunoreactivity to PP and PYY paralleled that of 5-HT, with greater numbers of cell bodies present in the different locations within the scolex nervous system, and the sucker plexus being more prominent. The number of PP-reactive cells in the lateral ganglia and main lateral, longitudinal nerve cords increased over the 24-h period in culture. Results with antisera of different specificities to PP and PYY suggest that the immunoreactivity may be due to a peptide with closer structural affinity to PYY than to PP. Immunoreactivity to PHI is restricted to the main lateral nerve cords in the body of 0-h worms, extending into the median nerve cords by 12 h and 24 h. Immunoreactivity to GRP became evident after 12 h in culture and was confined to the longitudinal nerve cords, in particular the median nerve cords. The results are discussed in relation to the proposed transmitter and regulatory roles of 5-hydroxytryptamine and the neuropeptides.

Animals↗
PubMed1981

Effect of mebendazole against Echinococcus granulosus and Taenia hydatigena cysts in naturally infected sheep and relevance to larval tapeworm infections in man.

The ability of three treatment schedules of mebendazole to kill well-established hydatid cysts was studied. Pregnant sheep, naturally infected with Echinococcus granulosus and/or Taenia hydatigena, were treated daily with mebendazole at a dose rate of 50 mg/kg body weight for either five days, one month, or three months. At autopsy, seven months after the commencement of treatment, no evidence was found that the 5-day treatment schedule had any damaging effect on E. granulosus cysts. The effects of the one month treatment were equivocal. There was evidence of a damaging effect from the 3-month treatment schedule and protoscoleces were not infective to dogs. No T. hydatigena cysts survived the 1- and 3-month treatments, but organisms from the 5-day treatment were infective to dogs. These results for E. granulosus in sheep suggest that long-term treatment with mebendazole may be required in hydatid disease in man. The results obtained for T. hydatigena in sheep are discussed in relation to the treatment of cysticercosis from T. solium in man. Mebendazole showed no untoward effect on the sheep or their lambs.

Animals↗
PubMed1989

Coproantigens in gut tapeworm infections: Hymenolepis diminuta in rats.

A capture enzyme-linked immunosorbent assay (ELISA) for the detection of Hymenolepis diminuta coproantigen in detergent-solubilised faecal supernatants was developed. The assay was sensitive to 400 ng H. diminuta protein/ml faecal supernatant and to 30 ng/ml in PBS 0.3% Tween. Faecal antigen levels started to rise on day 7 post infection and peaked on day 20. Following drug treatment of infected rats with 10 mg/kg praziquantel, there was an initial steep rise in faecal antigen levels, followed by a decline to background levels for uninfected animals by day 7 post treatment. When assayed against faecal supernatants prepared from H. microstoma, H. citelli, Diphyllobothrium ditrenum, Necator americanus, Strongyloides ratti and Nematospiroides dubius infections as well as uninfected animals, all results from these groups were 2 SD below those for animals infected with H. diminuta. The application of such a test to important intestinal cestodiases in man is discussed.

Animals↗
PubMed1989

Development of immunoreactivity to the invertebrate neuropeptide small cardiac peptide B in the tapeworm Diphyllobothrium dendriticum.

Neurons immunoreactive to small cardiac peptide B (SCPb) occur in the scolex and neck region of adult Diphyllobothrium dendriticum. The localisation of the SCPb-IR neurons in the peripheral nervous system is very pronounced; they are closely associated to the bothridial musculature in the scolex. SCPb-IR neurons were not observed in plerocercoid larvae but appeared after cultivation in vitro at 37 degrees C for 30 h. Functional and developmental aspects of the SCPb-IR neurons are discussed.

Animals↗
PubMed1976

[Oribatids (Oribatei, Acari) as intermediate hosts of Ctenotaenia marmotae (Frölich, 1802), a tapeworm parasitic in marmots (author's transl)].

Out of 30 species of Oribatids (from 23 genera), which were provided with eggs of Ctenotaenia marmotae in the laboratory, 24 proved to be potential intermediate hosts. The course of development of the parasite in the intermediate host could be followed up as far as to the cysticercoid (Figs. 2-8). It largely corresponds to the development of other Anoplocephalidae. After 113 days p.i. (test temperature 18-20 degrees C) the cysticercoid stage was reached. In the Pölla valley (Carinthia), at sea level of 2,200 m, the droppings of marmots scattered on the grass andmingled with proglottids of C. marmotae were marked. 9 months later 24 grass samples were taken and examined as to infected Oribatids. Out of a total of 12,100 specimens 49 turned out to be infected with cysticercoids; these specimens, however, belong to the species of Trichoribates incisellus (Kramer) and Trichoribates trimaculatus (C.L. Koch). They were taken from 16 samples with a total of 8,400 Oribatids. This is the first evidence under natural conditions of Oribatids acting as intermediate hosts to C. marmotae. It is presumed that 2 seasonal invasion peaks occur in the final host Marmota marmota (L.).

Animals↗
PubMed2006

A behavioral study of the beetle Tenebrio molitor infected with cysticercoids of the rat tapeworm Hymenolepis diminuta.

The host-parasite relationship, Tenebrio molitor-Hymenolepis diminuta, was analyzed. The learning behavior of infected and uninfected (control) beetles in a T-maze was compared. The infected beetles moved much slower in the T-maze than the controls. The infected beetles reached the same level of learning as the controls. However, they needed more trials than the controls. The effect of the infection was already distinct after the first week and even higher after the second week. This indicates that the initial phase of infection caused stress in the beetles. Longer infection did not worsen their ability to learn. Thus, the parasites clearly changed the behavior of their intermediate host and probably made them more susceptible to their final host, the rat.

Animals↗
PubMed2005

Growth, nutritional composition, and hematology of Arctic charr (Salvelinus alpinus) exposed to toxaphene and tapeworm (Diphyllobothrium dendriticum) larvae.

Toxaphene, an organochlorine pesticide, is the major contaminant of Arctic charr (Salvelinus alpinus) in the Canadian Arctic. The objective of this study was to investigate the combined effects of toxaphene exposure and infection by the larval stage of the cestode Diphyllobothrium dendriticum on fish growth, nutritional composition, and hematology. Hatchery-reared Arctic charr were subjected to one of four treatments: (1) oral administration of corn oil (control); (2) single oral dose of 10 microg/g wet wt toxaphene dissolved in corn oil; (3) exposure to 15 larval D. dendriticum; and (4) exposure to toxaphene and D. dendriticum in combination. The experiment was run for 104 days. Mean final toxaphene concentrations in charr muscle were 0.121, 0.336, 0.131 and 0.458 microg/g wet wt in each treatment group, respectively. Exposure to toxaphene and D. dendriticum decreased fish growth and condition as well muscle lipid and protein content. However, toxaphene did not increase the susceptibility of Arctic charr to parasite infection. Overall, 25 of 40 fish (62.5%) exposed to larval D. dendriticum became infected. Parasitized charr had decreased hematocrits and increased lymphocyte:erythrocyte ratios. Although total blood cell counts were decreased in all treatments compared with controls, differential leucocyte counts were unaffected. Our results suggest that toxaphene does not moderate Arctic charr resistance to D. dendriticum and there is no contaminant-parasite interaction at environmental levels.

Animals↗
PubMed2002

Ultrastructure of smooth muscle, gap junctions and glycogen distribution in Taenia solium tapeworms from experimentally infected hamsters.

Taenia solium adults were grown in hamsters infected by feeding them with cysticerci from pig carcasses. Viable strobilae were collected from the hamster duodenum 20-60 days post-infection, fixed and processed for transmission electron microscopy (TEM). Fourteen strobilae were cut into pieces and embedded in individual blocks. Sections, stained with toluidine blue, were then photographed by light microscopy. Over 1,200 TEM images were obtained from selected blocks. Maturing proglottids exhibited a dense myofilament lattice of connecting fibers, each contained in sarcoplamsic extensions of myocytons and emitting cytoplasmic processes loosely attached to other cells, structures characterized as myocyton-myofilament-pseudopod units, which are interpreted as structures involved in the transport of cells and membrane-bound-glycogen from the germinative tissues to mature proglottids. Densely packed membrane-bound glycogen particles were found between the tegumentary cytons of the neck tissue, and as single-stranded particles between the tegumentary cytons of mature proglottids. These were wrapped around cell bodies in the parenchyma of maturing proglottids and as thin cytoplasmic strands between the testicular lobules of mature proglottids. A large number of cell-to-cell adhesions were identified as gap junctions connected to glycogen strands. We suggest that these are involved in the transport of glucose to differentiating tissues.

Animals↗
PubMed2003

NO nerves and their targets in a tapeworm: An immunocytochemical study of cGMP in Hymenolepis diminuta.

We studied the pattern of cGMP immunostaining (IS) after stimulation with a nitric oxide donor in the presence of an inhibitor of phosphodiesterase in adult Hymenolepis diminuta. cGMP-IS was detected in the peripheral nervous system, especially in nerve fibres close to the body muscle fibres. cGMP-IS also occurred in terminals beneath the basal lamina of the tegument and between the muscle fibres of the suckers. The pattern of cGMP-IS was compared to that of 5-HT-IS and GYIRFamide-IS. TRITC-conjugated phalloidin was used to stain the musculature.

Animals↗
PubMed2004

The phylogeny of diphyllobothriid tapeworms (Cestoda: Pseudophyllidea) based on ITS-2 rDNA sequences.

Phylogenetic analysis of sequences of the ITS-2 rRNA genes of 20 samples of pseudophyllidean cestodes of the family Diphyllobothriidae (Ligula, Digramma, Diphyllobothrium, and Schistocephalus) from different hosts and geographical regions revealed that: (1) the inclusion of ligulids (previously family Ligulidae) to the Diphyllobothriidae is correct; (2) Schistocephalus appears as the most basal taxon of the Diphyllobothriidae, well separated from Ligula and Digramma, thus supporting the validity of Schistocephalinae Dubinina, 1962; (3) Digramma belonged with samples of Ligula, thus suggesting its invalidity as a genus; and (4) isolates of Ligula, presumably belonging to Ligula intestinalis, are paraphyletic, indicating that this species may represent a complex of separate taxa. Our results indicate the necessity for a taxonomic revision of the family Diphyllobothriidae.

Animals↗
PubMed2005

Taeniid tapeworm responses to in vitro glucose.

Experimental taeniid strobilae from Taenia solium and T. crassiceps (WFU strain) were incubated for 0-72 h in 0, 5 or 20 mM glucose solutions and further exposed for 15 min to the gap junction fluorochrome Lucifer Yellow. Frozen sections were obtained from each worm and observed under an epifluorescent microscope. Worm sections from strobilae incubated with glucose, revealed intense fluorescence in the base of the tegumentary surface, suggesting that this tissue behaves as a gap junction complex. Fluorescence intensity differences between control worms not exposed to glucose and worms incubated with glucose, were highly significant. The results demonstrate that under in vitro conditions, glucose is taken up along the whole strobilar tegument in both taeniid species, suggesting, that although taeniids attached to the duodenum probably take up most of their nutrients directly from the mucosal wall, the capacity for absorbing glucose along the tegumentary surface is always active and may increase the survival capacity of these intestinal worms by promoting glucose absorption at other points in the intestinal lumen.

Absorption↗
PubMed1998

Ultrastructure of the spermatozoon of the bank vole tapeworm, Paranoplocephala omphalodes (Cestoda, Cyclophyllidea, Anoplocephalidae).

The mature Paranoplocephala omphalodes spermatozoon is filiform, tapered at both ends and lacks mitochondria. Its anterior extremity exhibits an apical cone of electron-dense material measuring about 900 nm in length and 200 nm in width, and two crested-like bodies. The cortical microtubules follow a 25-35 degrees helicoidal path along their whole length, except at the posterior extremity where they become parallel to the spermatozoon axis. They are arranged in a single or two fields which may cover each other partially. The axoneme, of the 9 + "1" pattern of the Trepaxonemata, lacks a peri-axonemal sheath and does not reach the extremity of the spermatozoon. The nucleus is a compact and irregular cord coiled in a spiral around the axoneme. Moreover, we report for the first time a nucleus in the spermatozoon of a Cyclophyllidea species which reaches beyond the axonemal posterior extremity. The cytoplasm, depending on the level where the section is cut, is slightly electron dense or electron lucent and contains numerous small electron-dense granules in regions III-V. In the posterior spermatozoon extremity, granular material is replaced by a terminal and compact electron-dense material.

Animals↗
PubMed1999

A chromosome study of the tapeworm Bathybothrium rectangulum (Bloch, 1782) (Cestoda: Pseudophyllidea).

The diploid number 2n = 18 was revealed in Bathybothrium rectangulum, a specific parasite of barbels (Barbus spp.). All chromosome pairs were biarmed (pairs 1, 4, 7, 8, and 9 were metacentric; pairs 2, 3, and 6 were meta-submetacentric; and pair 5 was submetacentric) and small (from 1.49 to 2.95 microm). The C-banding method revealed pericentromeric heterochromatin in pairs 1, 3, 5, and 7; distinct C-bands in pairs 2, 4, 8, and 9; and a slight band in short arms of pairs 1 and 6. The karyotype of B. rectangulum is discussed with respect to the irresolute taxonomic position of B. rectangulum within the Pseudophyllidea.

Animals↗