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PubMed2001

Echinococcus granulosus: regulation of leukocyte growth by living protoscoleces from horses, sheep, and cattle.

To determine whether living hydatid tissue can, like hydatid fluid, regulate leukocyte growth, T-cell, B-cell, and macrophage lines were cocultured with protoscoleces of Echinococcus granulosus and their growth was compared with that of control cultures by thymidine uptake estimates and chemiluminescent assays of cell number. Protoscoleces supported mitosis of IL-1-deprived D10 T cells, but did not increase D10 count. The action of protoscoleces was affected by the species and organ of their origin and the length of time in culture. Unusually marked mitotic reaction, unaffected by parasite age and origin, was recorded in the B-cell line, BSM, also without commensurate count increase, indicating that induced mitosis resulted in cell loss. It is concluded that protoscoleces can induce mitosis in B and T cells of particular lineages and that this is a potential means of producing the pathological proliferation and depletion of B- and T-cell areas which characterize local reaction to hydatids.

Animals↗
PubMed1977

Detection of the Echinococcus granulosus diagnostic arc 5 in sera from patients with surgically-confirmed E. multilocularis infection.

The Echinococcus granulosus diagnostic arc 5 was revealed by sera from an Alaskan and a Swiss patient with surgically confirmed E. multilocularis infections. The possibility of each patient harboring a concurrent infection with both parasites may be disregarded on the basis of radiologic, scintillographic and surgical data. This conclusion is compatible with ecologic and epidemiologic considerations. These observations suggest that the immunoelectrophoresis test based on arc 5 positivity is not E. granulosus-specific as originally described.

Adult↗
PubMed1976

The development of brood capsules and protoscolices in secondary hydatid cysts of Echinococcus granulosus. A histological study.

Using the Mongolian jird (Meriones unguiculatus) as a laboratory host for the cystic stage of the British horse strain of Echinococcus granulosus, the mode of development of brood capsules and protoscolices was studied histologically. The successive stages in development in secondary hydatid cysts are described and shown to correspond closely with previous observations on primary hydatid cysts. The usefulness of this experimental model for future ultrastructural studies is emphasized.

Animals↗
PubMed1978

Serial passages of larval Echinococcus granulosus from equine origin in mice. I. Infection with protoscolices.

Starting with protoscolices from Echinococcus granulosus cysts of equine origin it was possible to isolate and maintain several "strains" of the parasite in mice through successive transfers of protoscolices. The most advanced strain is now in its 7th generation. Several criteria to evaluate the results are presented and discussed. It is concluded that serial echinococcosis of E. granulosus through passages with protoscolices is a practical method to maintain different strains for fundamental and applied comparative studies.

Animals↗
PubMed1988

Evidence of in vitro germinal layer development in Echinococcus granulosus cysts.

In vitro protoscolices of Echinococcus granulosus grew in a vesicular direction. After 9 days the laminated layer was observed; it reached thicknesses up to 140 micron. By day 125 of culture, the cysts had reached sizes of up to 4.875 micron and a high percentage of cysts had been obtained (10.4%). The ultrastructure of these cysts was studied and the existence of a germinal layer was demonstrated.

Animals↗
PubMed1985

Treatment of cystic echinococcosis (Echinococcus granulosus) with mebendazole: assessment of bound and free drug levels in cyst fluid and of parasite vitality in operative specimens.

Chemotherapy of the larval stage of Echinococcus granulosus in man with high oral doses of mebendazole has only been partly successful. In order to improve effective pharmacotherapy of this disease with mebendazole, the optimal time for blood sampling has been assessed and the mebendazole concentrations acting on the parasite have been compared with their viability. The optimal time for blood sampling was analysed in 14 patients during longterm treatment with mebendazole. The plasma level 4 h after the morning dose exhibited the best correlation with the average 24-h concentration, suggesting that the plasma level should be monitored 4 h after the morning dose. In 22 patients undergoing surgery for hydatid disease, the mebendazole concentration in cyst fluid was significantly correlated with its plasma level 4 h after the morning dose. In 13 of them the free drug concentration was determined by equilibrium dialysis and it was almost identical with the free mebendazole concentration in plasma. Results of viability tests in 12 cases revealed viable cysts in 6 cases and possibly viable cysts in 6 other cases. Even patients treated for more than 12 months still had viable cysts.

Adult↗
PubMed1981

Effect of praziquantel on adult Echinococcus granulosus in vitro: scanning electron microscopy.

The effect of praziquantel in vitro at concentrations of 5, 50 and 500 ppm for 1 h resulted in the progressive breakdown of the tegument and in morphologic distortion of adult Echinococcus granulosus when compared to controls. Scanning electron microscopy of all specimens treated in the various concentrations of praziquantel showed loss of most, if not all of the rostellar hooks and changes in the structure of the suckers. Many of the tapeworms immediately detached from the host's gut upon being placed in the drug, and all treated cestodes exhibited contraction or swelling, particularly in the penultimate proglottid. Intense contraction was apparent in the worms exposed to the higher drug concentrations. Characteristic conical microtriches on the terminal proglottid, as observed in the control specimens, became fused and matted when exposed to 5 ppm of praziquantel. At a drug concentration of 50 ppm, the tegumental surface developed grooves or furrows between clumps of fused microtriches, while 500 ppm caused production of holes within the denuded tegument of the parasite. Ovoid bodies, presumed to be eggs, were observed on the outer surfaces and just below the tegument of tapeworms treated with concentrations of 50 ppm. These structures also appeared to adhere to the outer surfaces of specimens exposed to 500 ppm. In view of the foregoing, special care should be taken in handling and disposing of feces from infected or suspect dogs after praziquantel treatment, since the breakdown in the tegumental surface of E. granulosus presumably results in the release of potentially infective eggs.

Animals↗
PubMed1981

Cytotoxicity of Echinococcus granulosus cyst fluid in vitro.

In a cytotoxicity assay, using rat spleen cells as target cells, Echinococcus granulosus cyst fluid from cattle exerted a marked degree of cytotoxicity in vitro. When trypan blue exclusion or [3H]thymidine incorporation by concanavalin A stimulated spleen cells was used as a measure of cell viability, dialyzed cyst fluid showed maximum cell destruction up to a 1:8 dilution. The effect was dose and time dependent, cells being affected by 24 h after exposure to cyst fluid. The components responsible for cytotoxicity of cyst fluid were heat stable and could be recovered using gel chromatography on Sephadex G 50 and G 15 as a single low molecular weight fraction. It is assumed that the toxic products released by the living parasite can readily penetrate through the cyst wall into the surrounding host tissue. The interference of such substances with immunocompetent cells might account for the long-term survival of the parasite in the intermediate host.

Animals↗
PubMed1981

On the nature of the proglottids of cestodes: a light and electron microscopic study on Taenia, Hymenolepis, and Echinococcus.

The organisation of five species of cyclophyllidean cestodes (Hymenolepis nana, H. diminuta, H. microstoma, Taenia (Hydatigera) taeniaeformis, Echinococcus multilocularis) has been studied using light and electron microscopy (SEM, TEM). It was found that there is no indication of any internal structure separating the proglottids, which are recognisable superficially. Thus in cestodes there is no metameric segmentation as in annelids. The implications of these findings on the terminology of tapeworm morphology are critically discussed.

Animals↗
PubMed1985

Cryopreservation of Echinococcus multilocularis metacestodes and subsequent proliferation in rodents (Meriones).

Four isolates of larval Echinococcus multilocularis originating from Switzerland (CH/1, CH/6 and CH/22) and Alaska (A/1) were used to prepare crude homogenate or small tissue fragments (STF) in Eagle's Minimal Essential Medium with Earle's salts (EMEM/A), or 0.2 g tissue blocks (TB) which were suspended in the same medium. After addition of dimethylsulfoxide or glycerol in final concentrations of 5% and 10% (v/v), respectively, aliquots of 1.0 ml, containing either 0.1 ml crude homogenate or STF, or one block of 0.2 g, were kept in cryotubes for 30 min at +2-4 degrees C (precooling phase), cooled subsequently to lower temperatures following a two-step or three-step schedule and finally plunged into liquid nitrogen (-196 degrees C). After storage for one week the samples were rapidly thawed at +37 degrees C for approximately 3 min, washed in fresh EMEM/A (37 degrees C) and transferred into the peritoneal cavity of Meriones for viability testing. As judged by histological examinations and metacestode weights of each 24 Meriones infected with cryopreserved homogenate, STF or TB, respectively, 46%, 87% or 100% contained viable, proliferating parasites. The best proliferation rate occurred when 10% glycerol was used as cryoprotectant and after precooling a three-step freezing schedule was employed (30 min at -28 degrees C, 30 min at -80 degrees C, transfer to liquid nitrogen). Cooling rates were determined as 0.7, 1.0 and 1.7 degrees C min-1 for the precooling phase, step 1 and step 2, respectively, and estimated as 65 degrees C min-1 for step 3. These results demonstrate that metacestodes of E. multilocularis can be successfully maintained by cryopreservation without losing their proliferative capacity in the intermediate host.

Animals↗
PubMed1983

Proliferation and metastases formation of larval Echinococcus multilocularis. II. Ultrastructural investigations.

The larval stage (metacestode) of Echinococcus multilocularis was studied by means of electron microscopy (SEM, TEM) before and after subcutaneous transplantation to jirds (Meriones unguiculatus) and in their lymph nodes and lungs with parasite metastases. It was found that the metacestode consists of a network of solid, cellular protrusions (buds) of the germinal layer which transform to tube-like and cystic structures devoid or with a laminated layer. Proliferation of the metacestode apparently occurs by protruding filamentous solid cell columns (buds) from the germinal layer. Their tips have diameters of only one cell: they are covered with a smooth syncytial tegument without microtriches and are filled with undifferentiated cells which contain a nucleus with a large nucleolus. The tegument is constantly enlarged by fusion with the underlying undifferentiated cells that divide repeatedly. At some distance from the tip a cavity develops inside the protrusion, thus finally giving rise to a tube-like structure which may transform to a cystic expansion. Simultaneously, the surface of the protrusion changes by the formation of microtriches and the occurrence of an amorphous laminated layer. The latter is concentrically covered by connective tissue cells and large amounts of collagen. Within cyst-brood capsules, finally protoscoleces are formed from accumulations of undifferentiated cells beneath the tegument. The study has unequivocally proven the cestode nature of the cellular protrusions, and it is assumed that detachment of cells from these structures and their subsequent distribution via the circulation may play a role in the formation of metastases. The origin of the laminated layer is discussed.

Animals↗
PubMed1979

Humoral response to sheep red blood cells in C57L/J mice during early and chronic stages of infection with Echinococcus multilocularis cysts.

C57L/J male mice infected with Echinococcus multilocularis cysts were challenged intraperitoneally at 4, 8, and 12 weeks postinfection (p.i.) with 3 x 10(9) sheep erythrocytes. The direct plaque forming cells, 2-mercaptoethanol (2-ME) sensitive (4-day sera) and 2-ME-resistant (8-day sera) haemagglutinin responses were significantly elevated at eight and 12 weeks p.i. as compared to controls or the fourweeks postinfected mice. Possible mechanisms of immunopotentiation in the chronically infected mice is discussed in relation to the larval cyst mass, splenomegaly, and B cell hyperplasia in the lymphoid tissues during the course of infection.

Animals↗
PubMed1983

Observations on Echinococcus multilocularis in the definitive host.

Six dogs were found to be susceptible to experimental infections with a European isolate of Echinococcus multilocularis from southern Germany. Two cats were only poorly susceptible. Adult worms were not evenly distributed throughout the small intestine and the majority of parasites were found in the posterior region. The mode of attachment of E. multilocularis in the dog was similar to that for E. granulosus with the adult worm extending its rostellum deep within a crypt of Lieberkühn. In cats only few worms were found to have penetrated deeply between the villi. E. multilocularis was found to possess a modified group of rostellar tegumental cells, morphologically and functionally identical to those described in E. granulosus and previously referred to as the "rostellar gland". By studying development in vivo and in vitro, the time required for the production of shelled eggs was demonstrated to be only 28 days. Concurrent experimental infections in dogs with E. multilocularis and E. granulosus revealed that both species will develop together in the same host. Their development was not retarded in any way by the presence of the other and both species were able to coexist in the same area of the intestine.

Animals↗
PubMed1983

Serological differentiation between Echinococcus granulosus and E. multilocularis infections in man.

An enzyme-linked immunosorbent assay (ELISA) was adapted for the serological differential diagnosis of cystic or alveolar echinococcosis in man caused by Echinococcus granulosus or E. multilocularis respectively. By affinity chromatography using rabbit anti hydatid fluid IgG coupled covalently to CNBr-Sepharose 4B a protein fraction (Em 1) containing shared antigens of both parasites could be isolated from an extract of E. multilocularis metacestode tissue. From the same source another antigen fraction (Em 2) with a high degree of specificity for E. multilocularis was prepared by immunosorption. Antigen Em 1 was equally sensitive for the detection of antibodies against E. granulosus and E. multilocularis, whereas antigen fraction Em 2 appeared to be more specific for E. multilocularis. A correct serological differential diagnosis was achieved in 95% of 57 confirmed cases of human cystic or alveolar echinococcosis by the simultaneous use of both antigen fractions in the ELISA and by comparison of their reactivities.

Animals↗
PubMed1978

Serial passages of larval Echinococcus granulosus from equine origin in mice. III. Infections with sterile daughter cysts.

Daughter cysts 0.2-3.0 mm in diameter from secondary Echinococcus granulosus cysts, collected from mice one year after experimental infection, were transferred to fresh mice. The metacestodes developed into larger cysts showing fertility and daughter cyst formation at autopsy 9-14 months post infection. The average total growth of all cysts per mouse expressed in log weight (mg) amounted to 0.25 +/- 0.03 per month. Thus, for the maintenance of the parasite in mice, daughter cysts can be used as successfully as protoscolices and small 'latent' cysts.

Animals↗
PubMed1982

Echinococcus granulosus: the influence of mebendazole therapy on the ultrastructural morphology of the germinal layer of hydatid cysts in humans and mice.

Upon ultrastructural examination it was found that prolonged mebendazole therapy of patients with hydatid disease often resulted in complete necrosis of the germinal layer of Echinococcus granulosus cysts. The affected cysts showed only remnants of degenerated germinal layer tissue including heterogeneous vesicular membranes, electron-dense amorphous structures, myeloid bodies, lipid globules, crystal-like precipitates and remnants derived from muscular tissue. Examination of the hydatid cysts of treated mice revealed the same time-related deteriorative effect of the anthelmintic as described previously for other cestode species. The advanced stage of degeneration of the germinal layer tissue observed in the murine cysts after treatment resembled the morphologic features present in the necrotic human cysts and gave additional information about the degeneration phenomenon.

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↗