Chuan-Min Yen

Larvicidal activities of ginger (Zingiber officinale) against Angiostrongylus cantonensis.

In this study, we investigated the anthelmintic activity of [6]-gingerol, [10]-shogaol, [10]-gingerol, [6]-shogaol and hexahydrocurcumin, a constituent isolate from the roots of ginger (Zingiber officinale), for the parasite Angiostrongylus cantonensis. This study found that the above constituents killed A. cantonensis larvae or reduced their spontaneous movements in a time- and dose-dependent manner. The larvicidal effect or ability to halt spontaneous parasite movement of [10]-shogaol, [6]-gingerol, [10]-gingerol, [6]-shogaol and hexahydrocurcumin at various concentrations was reached from 24 to 72 h, respectively. Further investigation to determine minimal effective doses of [10]-gingerol and hexahydrocurcumin revealed [10]-gingerol to have a greater maximum larvicidal effect and loss of spontaneous movements than hexahydrocurcumin, mebendazole and albendazole. These constituents of ginger showed effects against DPPH and peroxyl radical under larvicidal effect. Together, these findings suggest that these constituents of ginger might be used as larvicidal agents against A. cantonensis.

Sequence analysis in partial genes of five isolates of Angiostrongylus cantonensis from Taiwan and biological comparison in infectivity and pathogenicity between two strains.

Angiostrongylus cantonensis is the most common infectious agent causing eosinophilic meningitis and is present in Taiwan, Thailand and the Pacific islands. Clinical symptoms vary within different endemic regions, and their severity is probably dependent on the number of ingested parasites and the diversity among strains. The experimentally definitive host is the rat, and non-permissive hosts are certain mammals such as humans and mice. In this study, the partial gene sequences of two A. cantonensis strains isolated from five different regions in Taiwan were selected and molecularly analyzed. The internal transcribed spacer gene and cytochrome-c oxidase subunit I gene sequences of the Hualien (H) strain of A. cantonensis differed from those of the Pingtung (P) strain and the other three strains by 19% and 11%, respectively. We analyzed the infectivity, fecundity, and development of the H and P strain in rats and host pathogenicity in mice inoculated with both strains. The number of the emerged first-stage larvae, adult recovery, and average length of adults in Sprague-Dawley rats significantly differed between rats inoculated with the H and P strain. Young adult recovery, average length of young adults, eosinophil counts in the cerebrospinal fluid (CSF), glutathione peroxidase concentration, levels of reactive oxygen species as well as malondialdehyde concentration in the CSF, and the survival of mice significantly differed between BALB/c mice inoculated with the H and P strain. The H strain of A. cantonensis had lower infectivity, delayed fecundity, and poor development in rats, and caused milder pathology and lower mortality in mice than the P strain. These data clearly indicate that the H strain of A. cantonensis is a pathogenically distinct strain with lower infectivity to its definitive host, and causing mild pathogenic symptoms to its non-permissive host.

Antibodies of different immunoglobulin isotypes in serum and bile of patients with clonorchiasis

Specimens of serum and bile from patients were assayed by an enzyme-linked immunosorbent assay to reveal antibodies specific to antigens from adult Clonorchis sinensis. Antibodies of the IgG isotype showed the greatest elevation during infection (Students t-test, P < 0.001), whereas serum IgA and IgE and secretory IgA in bile were moderately elevated (P < 0.05). Major differences in the distribution of antibodies among the IgG subclasses were observed between patients who were and those who were not infected. IgG4 antibody levels were elevated in the serum and bile of infected patients, and there were significant correlations between the levels of IgG and IgG4 antibodies and the intensity of infection.

Kinetic change of oxidative stress in cerebrospinal fluid of mice infected with Angiostrongylus cantonensis

Abstract The cerebrospinal fluid (CSF) of C57BL/6 mice infected with Angiostrongylus cantonensis was examined for kinetic changes in oxidative stress parameters, including reactive oxygen species (ROS), superoxide dismutase (SOD), catalase, malondialdehyde (MDA), 8-isoprostane, and 8-hydroxy-2′-deoxyguanosine (8-OHdG). The ROS increased gradually in the early stage of infection. During days 12–30 post-infection, the infected mice revealed ROS levels significantly higher than that in uninfected controls (P < 0.001). The ROS levels peaked at day 24 and then returned to that observed in uninfected controls at day 45 post-infection. The kinetics of MDA, 8-isoprostane, and 8-OHdG concentration changes observed in the CSF of the infected mice corresponded with kinetic changes in ROS levels. Thus, the excess ROS caused lipid peroxidation and DNA damage to cells in the central nervous system (CNS) of mice infected with A. cantonensis despite the increased antioxidant SOD and catalase enzyme activities during post-infection days 12–30. The oxidative stress in the CNS of C57BL/6 mice was apparently increased by diseases associated with A. cantonensis infection.

The infectivity and antigenicity of Toxocara canis eggs can be retained after long-term preservation

Abstract Suspensions of fertilized eggs of Toxocara canis were mixed with 2% neutral formalin and preserved at 4°C. When, after storage for 0, 12, 18, 21 and 24 months, samples of the eggs were incubated at 30°C for 12 days, 96.8%, 92.6%, 74.1%, 51.0% and 19.3% of the eggs in the samples were found to embryonate. The embryonated eggs produced from the fertilized eggs preserved (in 2% neutral formalin at 4°C) for 0, 12, 18 and 21 months were then tested for their infectivity to BALB/c mice, each mouse being given 800 embryonated eggs. The numbers of larvae recovered from the mice and the sites from which they were recovered, 2 or 14 days post-infection, appeared unaffected by the length of storage of the eggs. The infected mice all had similar eosinophil counts in their peripheral blood and similar serum titres of Toxocara-specific IgM and IgG antibodies, and cultures of their spleen cells produced similar amounts of interleukin-4, interleukin-5 and interferon-γ when stimulated with concanavalin A. The results of SDS-PAGE indicated that egg preservation for at least 21 months had no effect on the excretory-secretory antigens in samples of medium from cultures of infective larvae released from the eggs. In summary, at least 50% of the fertilized eggs preserved in 2% neutral formalin at 4°C for 21 months could fully embryonate and then had the same infectivity and antigenicity as embryonated fresh eggs.

Effects of age and splenectomy on heavy infection of Angiostrongylus cantonensis in rats.

This study was designed to determine the effects of age and the role of spleen in rats with heavy Angiostrongylus cantonensis infection. Young rats (8 weeks) infected with 100 larvae were found to have significantly higher worm recovery rate (75.0±6.6%) than the adult (6 months) (55.7±1.5%) and the aging ones (13 months) (57.6±4.0%). Moreover, the recovery rate in adult rats with 400 larvae (33.6±10.67%) was significantly lower than those with 100 larvae (55.7±1.53%) or 200 larvae (53.3±5.4%). The splenectomized young rats with 100 larvae had a significantly higher recovery rate (84.3±2.5%) than the intact (75.0±6.6%) or sham splenectomized ones (74.4±3.8%). Although titers of antibody against A. cantonensis increased with time, those against young adults were significantly higher before week 4 whereas those against adult worms become significantly higher since week 4. Titers in the splenectomized rats were also found to be significantly lower than those in the intact ones. These finding indicate that young rats are more susceptible to A. cantonensis. Crowding effect may occur in rats with heavy infections. The effects of splenectomy on the host are independent of the intensity of infection.