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Malformations/anomalies in the development of cestodes
Aliaskerova, Madina ; Schreiber, Manfred (advisor) ; Chanová, Marta (referee)
Anomalies in tapeworms can appear spontaneously under natural conditions, at both morphological and developmental level. In adult tapeworms, malformations at morphological level are manifested on the scolex and strobila. Their detailed description can be found in Taenia saginata, Taenia pisiformis, Taenia solium, Dibothriocephalus nihonkaiense, Dibothriocephalus latus, Hymenolepis nana and Hymenolepis microstoma. In the larval stages of Taenia crassiceps, the malformations occur predominantly on the skolex. Morphological malformations may be manifested by multiplication of suckers or change in the appearance and number of hooks, change in the structure of the genitalia, occurrence of lateral segments, fenestration of the strobila or occurrence of multiple planes of symmetry. However, these malformations can also be caused by targeted radiation exposure, temperature stress or anthelmintics. Developmental anomalies are also manifested by spontaneous appearance of tapeworms in different parts of the body in different host species. There is a link between anomalous infections and the immune status of the host. Possible causes of anomalies include damage to neoblasts, lack of a proper immune response by the host, anthelmintics, host diet, or environmental influences.
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Influence of tissue helminths on the development of cancers in model organisms
Schreiber, Manfred ; Horák, Petr (advisor) ; Kolářová, Libuše (referee)
Mesocestoides corti and Taenia crassiceps are tapeworms, larvae of which are characterized by their ability to reproduce asexually. In this work, the effect of infection by M. corti and T. crassiceps in BALB/c, C57BL/6J and ICR mice on the growth and metastasis of B16F10 melanoma tumors was investigated. Although an increase in metastatic activities was observed after intravenous administration of melanoma cells to M. corti-infected mice, both tapeworms showed a strong suppressive effect on the size and number of tumors and metastases formed when the cells were administered intraperitoneally. This, in some cases, led to a complete elimination of tumor cells. In vitro cultivation of B16F10 cells in the presence of larval excretory-secretory products led to a decrease in their viability but an increase in their migration ability. Flow cytometry proved that M. corti infection has an effect on the increased number and proportion of macrophage populations in the peritoneum of ICR mice. Our work confirmed the anti-tumor effect of T. crassiceps infection in mice and introduced M. corti as a new helminth species capable of influencing cancer. Key words: helminths, cestodes, cancers, Mesocestoides corti, Taenia crassiceps
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Helminths as causative agents of vertebrate cancers
Schreiber, Manfred ; Horák, Petr (advisor) ; Kolářová, Iva (referee)
Opisthorchis viverrini, Clonorchis sinensis, and Schistosoma haematobium have been classified as the group 1 of carcinogens by the International Agency for Research on Cancer. Infections with opisthorchid flukes may lead to the development of cholangiocarcinoma of the liver, and those with schistosomes to the squamous carcinoma of the bladder. The link between helminth infections and carcinomas has been confirmed, and the exact mechanisms of carcinoma induction are at present intensively studied. There are some other representatives of helminths that are probably associated with cancers, but their direct effect on the process of carcinogenesis has not been confirmed yet. The formation of tumors can also occur via malignant transformation of totipotent parasite cells that become invasive and metastasize to different parts of the host body. However, some types of helminths may exhibit an opposite effect and show an anti-tumor activity. This review primarily focuses on the helminths associated with the development of cancer and the currently described mechanisms of carcinogenesis caused by such infections.
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