Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 91-106).

No description available.

Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaves 79-91).

No description available.

No description available.

Effects of infections with sylvatic species Trichinella, T. nativa or T. pseudospiralis, on the diel locomotory activity and locomotory activity pattern of an indigenous rodent host, the deer mouse (Peromyscus maniculatus), were assessed in a familiar environment and during the process of familiarization in a novel environment. Infection with muscle-encapsulating T. nativa severely reduced overall locomotory activity and changed locomotory activity patterns in a dose dependent fashion. In contrast, T. pseudospiralis infection had no such effects on diel locomotory activity. Infection with these nonencapsulating nematodes also changed locomotory activity patterns, but effects were independent of inoculation dose. Trichinella pseudospiralis infection almost completely reversed the locomotory exploration patterns of mice. Both T. nativa- and T. pseudospiralis-infected mice spent more time in shelter than did sham-inoculated conspecifics. Biological characterization of these infections in deer mice revealed striking departures from the conventional course of infection as typified by synanthropic trichinellosis in laboratory mice, and provided further insight into the relationship between the major phases of infection and the observed behavioral changes. Altered behaviors of infected deer mice are discussed in terms of their consequences on host fitness and survival, as well as parasite transmission. The study establishes links between behavioral observations derived from synanthropic and laboratory rodent-T. spiralis host-parasite associations and their sylvatic counterparts. It provides the behavioral underpinnings for future assessments of the role of wild rodents in the transmission of sylvatic trichinelloses.

No description available.

No description available.

Polymorphonuclear leukocytes infiltrate tissues in response to an inflammatory stimulus such as endotoxin or parasite products. Previous studies have shown an extensive cellular infilteration about the parasitized skeletal muscle of mouse infected with the nematode, Trichinella spiralis. Infection of the host with Trichinella pseudospiralis, on the other hand, is associated with a dramatic suppression of inflammatory cellular response. Prostaglandin Bi is a product of arachidonic acid metabolism and is synthesized by variety of cell types. Prostaglandins of the E series have been generally known to suppress inflammatory responses. In the present study, I have investigated the possible relation between plasma prostaglandin Bi levels and host cellular response in infected mice. Concentrations of prostaglandin Bi in mice plasma were measured at 5, 11, and 21 days after infection with larvae of either nematode species by enzyme immunoassay. There were noticeable elevations in the concentrations of prostaglanding Bi in samples of mice infected with Trichinella pseudospiralis compared to controls. Conversely, decreased levels of prostaglandin Bi were observed in samples from the mice infected with Trichinella spiralis. These results suggest that the differences observed in the host inflammatory response to infection with Trichinella spiralis versus Trichinella pseudospiralis might be associated with recognized properties of prostaglandin Bi· In this connection, I have suggested three possible mechanisms by which the differences of inflammatory response in relation to PGEi production may be explained.

The Genus Trichinella is currently thought to consist of 8 seperate species. Several methods have been used to help differentiate these. In this study the ability of three of these species, T. spiralis, T. pseudospiralis, and T. sp. 3 to idependantly infect MRL++ mice was compared at 5, 7, 11, 18 and 20 days post infection ( dpi) with the hope of discovering new distinguishing characteristics. Of interest was the development of inflammation through the accumulation of neutrophils associated with larvae of Trichinella in mouse skeletal muscle. This was evaluated with routine histological stains, endogenous peroxidase staining and immunohistochemical staining specific for neutrophil myeloperoxidase. The inflammatory response in skeletal muscle varied considerably among these three species with neutrophil accumulation being very heavy in the later stages of T. spiralis infection , mild in T. sp. 3 and virtually nonexistant in T. pseudospiralis infections. Also, the appearance of neutrophils was closely correlated with the development of a nurse cell or cyst in the larvae that develop these structures. In T. pseudospiralis where cyst formation is absent, there consistently was a lesser degree of inflammation. These results suggest a possible role of neutrophils involved in inflammation or the process of inflammation itself in the production of nurse cell formation as well as confirming previously described antiinflammatory capabilities of T. sp. 3 and T. pseudospiralis.