Biomedical subjects

R Lucius

Publications and source records attributed to R Lucius.

76 records · Page 5Linked to original sources

PubMed1980

Cerebral larvae in the second intermediate host of Dicrocoelium dendriticum (Rudolphi, 1819) and Dicrocoelium hospes Looss, 1907 (Trematodes, Dicrocoeliidae).

Cerebral larvae of Dicorcoelium dendriticum and D. hospes and the brains of infected ants were studied. Morphologic differences of the freed larvae could not be found, but there were evident differences in number and localization of the cerebral stages. Ants infected with D. dendriticum usually showed one "Hirnwurm" while in the majority of the ants infected with D. hospes two larvae were found. The typical localization of the "Hirnwurm" of D. dendriticum was in the ventral part of the subesophageal ganglion; almost every larva of D. hospes was found in the dorsal part of an antennal lobe. The cyst walls of the larvae were visible only in some specimens. Their thickness seemed to depend on the localization of the larva. Differences in number and localization of the larvae, and hypotheticalmechanisms how they could influence the behavior of their hosts are discussed.

Animals↗

PubMed1978

[A contribution to the biology of Dicrocoelium hospes Looss, 1907 (Trematoda, Dicrocoeliidae)].

In this study, carried out in the Ivory Coast, Dicrocoelium hospes Looss, 1907 was shown for the first time to be a parasite of cattle and it was also detected in sheep by the presence of ova in the faeces. Up to 50% of the sheep in some flocks were found to shed eggs. The adults, sporocysts, "slime balls" and cercariae of D. hospes are described and compared to the respective stages of D. dendriticum. This comparison shows that essential morphological structures are very similar, especially the sensory papillae, which as so called chaetotaxis can serve to distinguish closely related species. The cercariae develop in terrestrial snails of the genus Limicolaria of which several species may play a role (L. flammea, L. felina, L. kambeul). The main habitat of D. hospes seems to be limited to savannah environment; only once could D. hospes be found in the borderzone between savannah and the rain forest. Infected Limicolaria-snails shed the cercariae in amorphous "slime balls" of liquid-jelly-like consistency and yellowish colour. Under the influence of sunlight these liquify; the cercariae, however, can survive for up to 26 h. According to our present knowledge the sunlight seems to be a factor which triggers the shedding of slime balls. This begins shortly after sunrise at a temperature of 22 degrees C and a relative humidity of 100%. Infected snails can shed cercariae on seven consecutive days. This kind of slime ball production might provide a clue to the 2nd intermediate host; efforts to identify this host have, however, so far been fruitless, despite the fact that almost 4000 arthropods, mainly ants, have been investigated.

Animals↗

PubMedDate not supplied

Immunodiagnostic studies on Onchocerca volvulus and Mansonella perstans infections using a recombinant 33 kDa O. volvulus protein (Ov33).

A total detergent-soluble extract of adult female Onchocerca volvulus (OvAg) and a recombinant O. volvulus protein (Ov33) linked to glutathione-S-transferase (GST) were compared with regard to their serodiagnostic suitability for differentiating between O. volvulus and Mansonella perstans infections in a region endemic for both filarial worms in western Uganda. Using OvAg in an enzyme-linked immunosorbent assay (ELISA), 98.8% sensitivity was obtained examining 84 O. volvulus microfilariae (mf) carriers living in the hyperendemic area. However, 5 of 18 (28%) sera from M. perstans mf carriers without O. volvulus mf, from another area hypoendemic for O. volvulus, cross-reacted with OvAg. Using the recombinant antigen Ov33-GST in an ELISA and Western blot assay, sensitivity for O. volvulus remained high (97.2% and 98.8% respectively) while none of 90 sera from M. perstans mf carriers reacted positively. Both antigens were used to examine a batch of sera from 260 persons living in the onchocerciasis hyperendemic area who did not have mf in their skin snips (9.5% of 2728 persons examined); 116 of these sera (44.6%) were positive in the OvAg ELISA, compared to 85 (32.7%) and 69 (26.5%) which were positive in Ov33-GST ELISA and Ov33-GST Western blot, respectively. Reaction with GST alone was minimal. The recombinant antigen Ov33 efficiently differentiates between O. volvulus and M. perstans infections, and is sensitive when used to detect patent and prepatent or low-level O. volvulus infections.

Animals↗

PubMedDate not supplied

Toxoplasma infection and cell free extract of the parasites are able to reverse multidrug resistance of mouse lymphoma and human gastric cancer cells in vitro.

A large number of compounds are known to reduce the ATP-dependent efflux pump activity of multidrug resistant (mdr) tumor cells. Here we report that an infection of cancer cells with T. gondii reduced the multidrug resistance of the tumour cells against cytostatic drugs. Two mouse lymphoma cell lines (Mdr L 5718 and Par 5718) were infected with Toxoplasma gondii in vitro and the reduction of efflux pump activity of the cells was measured. The drug accumulation (Rhodamin-123) was increased in the infected mdr cell lines compared with non- infected mdr-cells, and no effect was shown after infection of the parental cell line. The same effect was also achieved by incubation of Mdr-tumor cells with cell lysate of Toxoplasma gondii. Mdr-1-gene expression was reduced in the infected cell lines 48 hours after infection. Co-cultivation of Toxoplasma gondii with mdr cell lines separated by a microfilter from tumor cells was performed, but this cocultivation did not change the mdr efflux activity. The effect of Toxoplasma gondii infection on the efflux pump activity and mdr-1 gene expression was also examined in the human gastric cancer cells. A sensitization of resistant gastric cancer cells was also achieved by parasite infection. This phenomenon is an evidence that a reduction of resistance in tumor cells can be achieved by a natural parasite infection. It is as yet unclear whether an active infection or another substance of T. gondii is responsible for this phenomenon.

ATP Binding Cassette Transporter, Subfamily B, Mem↗