Synergistic action of a cyclic depsipeptide and piperazine on nematodes.

The present study describes the synergistic effects of the cyclic depsipeptide BAY 44-4400 and piperazine in the treatment against the nematodes Trichinella spiralis, Heligmosomoides polygyrus, and Heterakis spumosa. The in vitro anthelmintic activity of a combination of the two compounds (1.7 motility units) against T. spiralis larvae was significantly higher than the sum of the individual drug effects (1.3 motility units). With regard to the rate of expulsion of H. polygyrus worms from the intestine of infected mice, an additive effect was observed; piperazine alone exerted an efficacy of 54.4% and BAY 44-4400 alone, one of 44.4%, whereas the combination of these compounds had an efficacy of 97.5%. With regard to the expulsion of H. spumosa worms, the effect of the combination was more than 5 orders of magnitude greater than the sum of the effects of the single compounds, i.e., there was a considerable potentiation of the actions of BAY 44-4400 and piperazine. Moreover, the combination exerted a significantly higher degree of degenerative effects on the intestine and on the nerve chords of H. spumosa as compared with the single compounds.

An ultrastructural and histochemical study of oogenesis in the trichostrongylid nematode Heligmosomoides polygyrus.

Oogenesis in trichostrongylids has been examined for the first time in a light and electron microscopic investigation of Heligmosomoides polygyrus. The female reproductive tract is a single straight tube containing small oogonia (6 micron in diameter), which are arranged in a rosette pattern around a central rachis at the anterior end of the tract. Developing oocytes separate from the rachis and pass posteriorly in single file down the growth zone. Oocytes increase rapidly in volume due to the accumulation of cytoplasmic inclusion granules. These granules are of 3 types. Type 1 granules are amorphous and probably consist primarily of lipoprotein. Type 2 granules are large lipid inclusions and type 3 granules are electron-dense lipoprotein yolk bodies, which are probably used for energy reserves in the developing embryo. Histochemical studies show a more intense reaction for DNA in the nuclei of oogonia than in the nuclei of oocytes. There is a strong reaction for RNA in the nucleoli and in the cytoplasm of oogonia and oocytes. Ultrastructural studies indicate that this RNA is probably in the form of rRNA in the abundant ribosomes. Mature oocytes are cylindrical (60 X 70 micron), have a distinct nucleus with nuclear pores, and the cytoplasm is filled with inclusion granules and ribosomes but contains only small amounts of glycogen. Prior to fertilization the plasma membrane of oocytes acquires a flocculent coat. These oocytes contain 6 distinct bivalent chromosomes in diakinesis. Thus the major changes that occur in developing germ cells are 2-fold: nuclear changes that prepare the chromosomes for fertilization by initiating reduction division, and cytoplasmic changes that involve the synthesis and storage of inclusion granules.

Antigen stripping from the nematode epicuticle using the cationic detergent cetyltrimethylammonium bromide (CTAB).

The cuticular antigens of adult Nematospiroides dubius were selectively removed using the cationic detergent cetyltrimethylammonium bromide (CTAB). Nonionic, zwitterionic or anionic detergents were ineffective in comparison. The biochemical profile of the antigens removed by detergent was identical to that of surface antigens removed by homogenization, with the added advantage that detergent-stripped antigens lacked many of the background antigens (excretory/secretory--ES and somatic) seen in homogenates. In addition, the detergent was shown to act in a non-invasive manner as electron micrographs failed to reveal any gross damage to the nematode outer cuticle. The observed selective release of significant quantities of relatively clean nematode surface antigen by CTAB in a non-invasive or destructive manner provides the impetus for definitive studies on the relevance of surface antigens (in the absence of ES or somatic antigens) to the overall immunogenicity of this and other parasites.