Mucosal tolerance of the hookworm Ancylostoma caninum in the gut of naturally infected wild dogs.

Ancylostoma caninum is a very pathogenic hookworm that locates in the small intestine of the dog and other canid species. The mucosal response of wild dogs naturally infected with A. caninum was investigated in this study. In spite of diffuse infiltrations of the mucosa with CD3+ , CD4+ , CD8+ , CD11c+ , CD21+ or MHC class II antigen cells, no focal infiltrations with any of these cell phenotypes were observed around the buccal capsule or the body of the feeding worms. Very few or no apoptotic cells could be detected around the worms fixed into the mucosa but they were detected on the tip of villi and in the superficial layer of cellular debris and proteinaceous exudate that covers the mucosa. Muc5AC, a mucine associated with expulsion of gut worms (Trichuris muris) was expressed extremely weakly or was not expressed at all in the intestine of the wild dogs infected with A. caninum. Our data show that individual specimens of A. caninum can reside for some time in the mucosa of the gut of dogs undetected and most likely unaffected by the effectors of the local immune response.

Inactivation effect of sonication and chlorination on Saccharomyces cerevisiae. Calorimetric analysis.

The inactivation effects of ultrasonic irradiation at 27.5 kHz and chlorination using sodium hypochlorite solution (NaOCl) on the growth of Saccharomyces cerevisiae (yeast cells) were investigated. In order to evaluate the effect of ultrasound on the growth of the yeast cells, calorimetric analysis was carried out in addition to colony counting. The heat evolution produced by the growth of yeast cells detected by calorimetry showed completely different patterns between sonication and chlorination. In case of sonication, the yeast cells were inactivated almost like a bactericidal effect, i.e. a quantitative change in cell number, at the beginning of sonication. It was similar to patterns obtained on simple dilution of yeast cells. In contrast, longer sonication increased the bacteriostatic effect, i.e. qualitative damage of the cell growth activity, together with the bactericidal effect. These results suggest that the cavitation caused by ultrasonic irradiation initially disrupted the cells located near the cavitation bubble which caused immediate cell death and the growth activity of the surviving cells was gradually damaged by further sonication. On the other hand, only a bacteriostatic effect was observed when the yeast cells were inactivated by chlorination.