Search Results - (Author, Cooperation:L. Chappell)

2013-05-31

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Culicidae/*parasitology ; Erythrocytes/parasitology ; Host-Parasite Interactions/*immunology ; Insect Vectors/*parasitology ; Malaria/immunology/parasitology/transmission ; Malaria Vaccines/immunology ; Mice ; Mice, Inbred C57BL ; Plasmodium chabaudi/growth & development/*immunology/isolation & ; purification/*pathogenicity ; Serial Passage ; Virulence/immunology

1365-2826

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Infections of the gastrointestinal nematode, Nippostrongylus brasiliensis, in the laboratory rat result in a characteristic biphasic anorexia which is followed by hyperphagia once the worm burden has been cleared. Despite the importance of parasite-induced anorexia, relatively little is known of the underlying mechanisms. We have investigated the involvement of the central appetite drive in this anorexia by studying the gene expression of two neuropeptides with opposing actions on energy balance, NPY and CRF. Gene expression was assessed by in situ hybridization at 2, 8 and 16 days post-infection (p.i.) in infected rats, in uninfected controls, and in a group with food intake restricted to match that taken voluntarily by the parasitized animals. The sampling intervals corresponded to each of the two phases of maximum anorexia and the period of compensatory hyperphagia. Surprisingly, we found that increases in NPY gene expression in the hypothalamic arcuate nucleus (ARC) accompany anorexia in rats infected with N. brasiliensis; there was a significant relationship between degree of anorexia and induction of NPY mRNA after 8 days of infection. Furthermore, ARC NPY mRNA levels in parasitized animals were similar to those in pair-fed individuals with food intake restricted to match the infected rats. The number of larvae used to establish the infection affected both the degree of anorexia and the level of NPY mRNA at 8 days p.i. in a dose-dependent manner. NPY gene expression remained elevated in infected rats during at least the initial stages of compensatory hyperphagia. This suggests that animals detect a state of energy deficit during the early stages of the infection, yet do not feed, but become hyperphagic coincident with worm loss. The failure of anorectic parasitized animals to feed in response to activation of the NPYergic system makes this a novel system in which to study the regulation of hypothalamic NPY by physiological challenge. There were no significant differences in CRF gene expression between the groups at any of the sampling intervals.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The immune response of rainbow trout to cercariae and diplostomules of Diplostomum spathaceum was investigated. Following immunization, serum was tested for the presence of antibody, using an enzyme-linked immunosorbent assay (ELISA) and immunofluorescence. Circulating antibody was detected to both cercariae and diplostomules by 6–7 weeks postimmunization and the sera were tested for their cross-reactivity with the other larval stage, using an ELISA.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The immune response of rainbow trout to infection with the cercariae of the digenean parasite Diplostomum spathaceum was investigated. Rainbow trout infected with cercariae at weekly intervals, or injected with a suspension of dead cercariae, did not produce a specific humoral response against D. spathaceum cercariae, as tested using immunoperoxidase, agglutination and cytotoxicity assays. However, a significant difference occurred in the rate of infection of rainbow trout given weekly exposure to cercariae of D. spathaceum in winter and summer. Rainbow trout injected with a suspension of dead cercariae acquired significantly fewer metacercariae than controls when exposed to a challenge infection. This suggested a specific immune response by the host and is the first example of a reduction in the infection rate of rainbow trout immunized against a digenean parasite, when exposed to a challenge infection.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The killing ability of rainbrow trout macrophages for the infective larval stages of Diploslomum spathaceum, cercariae and diplostomules, was investigated. Isolated macrophages kill significant numbers of diplostomules at effector: target ratios of 150: 1 or greater. In vitro killing was not increased using antiserum-coated larvae or in vivo-activated macrophages individually, but when they were combined increased killed occurred. Diplostomules were capable of eliciting respiratory burst activity from macrophages in vitro, suggesting that reactive oxygen species may have a role to play in the killing mechanism. The importance of macrophage activation in the protection afforded by immunization against this parasite is discussed.

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Abstract. The degree of protection in immunized rainbow trout against the infective larval stages of Diplostomum spathaceum was investigated. Immunized rainbow trout demonstrated a 70–80% reduction in the number of metacercariae establishing in their eye-lenses following challenge with live cercariae compared with unimmunized fish. Both normal trout serum and anti–diplostomule serum weTC cytotoxic to diplostomules in vitro. However, there was no correlation between the degree of protection and the level of serum antibody within individual fish. Reduced establishment of migrating diplostomules, indicative of in vivo killing, occurred in fish possessing activated macrophages and challenged with cercariae opsonized with specific antibody. An antibody–dependent cell–mediated cytotoxic (ADCC) mechanism is proposed, conferring protection in immunized fish. This is supported by the finding that cercarial and diplostomule antigens are capable of activating macrophages in immunized rainbow trout. The role of macrophage activation and specific antibody in conferring protection in immunized fish is discussed.

Electronic Resource

0169-4758

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

0031-7977

Linguistics and Literary Studies

Classical Studies

0031-7977

Linguistics and Literary Studies

Classical Studies

1432-1327

Key words RNA cleavage ; Lanthanide(III) macrocyclic complexes ; Oligonucleotide-metal complex conjugate

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Abstract  Eu(III) complexes of two neutral bifunctional tetraaaza macrocyclic ligands {1-[1-carboxamido-3-(4-nitrophenyl)propyl]-4,7,10-tris(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane and 2-(4-nitrobenzyl)-1,4,7,10-tetrakis(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane} are prepared. Eu(III) complexes of the isothiocyanate derivatives of these macrocycles are treated with oligonucleotides containing 2′-O-propylamine linkers to form conjugates. Hydrolytic cleavage of an oligoribonucleotide is promoted by Eu(III) macrocyclic oligonucleotide conjugates containing complementary (antisense) sequences. Cleavage is not observed in the presence of Eu(III) conjugates containing scrambled sequences nor by free complex. Despite the fact that one of the free macrocyclic complexes is more reactive than the other, the extent of cleavage observed is similar for conjugates containing either Eu(III) macrocyclic complex.

Electronic Resource

1573-6865

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary Wheat germ agglutinin—gold and chitinase—gold complexes were used to demonstrate the presence of chitin on the surfaces of eggs of the animal parasitic nematodeOnchocerca gibsoni. The gold complexes were enhanced by silver intensification and examined by light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Distinctive labelling of the egg surfaces was obtained with both probes in all three microscope modes. The results indicate that the small colloidal gold markers (3–10 nm) commonly used for high resolution TEM studies may be silver enhanced and also used for sensitive LM and SEM studies.

Electronic Resource