ORCID Profile
0000-0002-4300-0364
Current Organisation
University of Tasmania
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Publisher: Springer Science and Business Media LLC
Date: 29-05-2012
Abstract: The primary olfactory pathway is a potential route through which microorganisms from the periphery could potentially access the central nervous system. Our previous studies demonstrated that if the olfactory epithelium was damaged, bacteria administered into the nasal cavity induced nitric oxide production in olfactory ensheathing cells. This study investigates the cytokine profile of olfactory tissues as a consequence of bacterial challenge and establishes whether or not the bacteria are able to reach the olfactory bulb in the central nervous system. The olfactory epithelium of C57BL/6 mice was damaged by unilateral Triton X-100 nasal washing, and Staphylococcus aureus was administered ipsilaterally 4 days later. Olfactory mucosa and bulb were harvested 6 h, 24 h and 5 days after inoculation and their cytokine profile compared to control tissues. The fate of S. aureus and the response of bulbar microglia were examined using fluorescence microscopy and transmission electron microscopy. In the olfactory mucosa, administered S. aureus was present in supporting cells of the olfactory epithelium, and macrophages and olfactory nerve bundles in the lamina propria. Fluorescein isothiocyanate-conjugated S. aureus was observed within the olfactory mucosa and bulb 6 h after inoculation, but remained restricted to the peripheral layers up to 5 days later. At the 24-h time point, the level of interleukin-6 (IL-6) and tumour necrosis factor-α in the compromised olfactory tissues challenged with bacteria (12,466 ± 956 pg/ml and 552 ± 193 pg/ml, respectively) was significantly higher than that in compromised olfactory tissues alone (6,092 ± 1,403 pg/ml and 80 ± 2 pg/ml, respectively). Immunohistochemistry confirmed that IL-6 was present in several cell types including olfactory ensheathing cells and mitral cells of the olfactory bulb. Concurrently, there was a 4.4-, 4.5- and 2.8-fold increase in the density of iNOS-expressing cells in the olfactory mucosa, olfactory nerve and glomerular layers combined, and granule layer of the olfactory bulb, respectively. Bacteria are able to penetrate the immunological defence of the compromised olfactory mucosa and infiltrate the olfactory bulb within 6 h even though a proinflammatory profile is mounted. Activated microglia may have a role in restricting bacteria to the outer layers of the olfactory bulb.
Publisher: Wiley
Date: 14-08-2006
Publisher: Bioscientifica
Date: 05-2000
Abstract: The zona pellucida glycoconjugate content of several marsupial species was investigated using differential lectin histochemistry. Ovaries from fat-tailed dunnarts, a southern brown bandicoot, grey short-tailed opossums, brushtail possums, ringtail possums, koalas and eastern grey kangaroos were fixed, embedded in paraffin wax, sectioned and stained with ten fluorescein isothiocyanate-conjugated lectins. Sections were also incubated with either neuraminidase or saponified, respectively, before incubation with the lectins to identify saccharide residues masked by sialic acids or O-acetyl groups on sialic acids. The zonae pellucidae surrounding the oocytes of the marsupials demonstrated interspecific variation in glycoconjugate content, with mannose-containing glycoconjugates exhibiting the greatest variation. Some of the zona pellucida glycoconjugates of all species, except those of the opossums, were masked by sialic acid with an increase in fluorescence with lectins from Arachis hypogea (PNA), and Glycine max (SBA), after desialylation. The disaccharide beta-galactose(1-4)N-acetyl-D-glucosamine appeared to be conformationally masked by O-acetyl groups of sialic acids in the zonae pellucidae of all species, with an increase in fluorescence with the lectin from Erythrina cristagalli (ECA), after saponification. Similar intensity and localization of beta-(1-4)-N-acetyl-D-glucosamine, as shown by staining of the lectin from Triticum vulgaris (WGA), to the inner and outer regions of the zona pellucida, were found to those reported in eutherian species. WGA fluorescence became uniform throughout the zonae pellucidae after saponification, indicating differential O-acetylation of sialic acids on the internal compartment of the zonae pellucidae.
Publisher: Springer Science and Business Media LLC
Date: 07-07-2008
DOI: 10.1007/S00018-008-8184-1
Abstract: Olfactory ensheathing cells (OECs) have been shown previously to express Toll-like receptors and to respond to bacteria by translocating nuclear factor-kappaB from the cytoplasm to the nucleus. In this study, we show that OECs extended significantly more pseudopodia when they were exposed to Escherichia coli than in the absence of bacteria (p=0.019). Co-immunoprecipitation showed that E. coli binding to OECs was mediated by Toll-like receptor 4. Lyso-Tracker, a fluorescent probe that accumulates selectively in lysosomes, and staining for type 1 lysosome-associated membrane proteins demonstrated that endocytosed FITC-conjugated E. coli were translocated to lysosomes. They appeared to be subsequently broken down, as shown by transmission electron microscopy. No obvious adherence to the membrane and less phagocytosis was observed when OECs were incubated with inert fluorescent microspheres. The ability of OECs to endocytose bacteria supports the notion that OECs play an innate immune function by protecting olfactory tissues from bacterial infection.
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/AM06016
Abstract: This is a pilot study to investigate the effects of incubating cumulus oophorus-encased ovarian oocytes of the common brushtail possum (Trichosurus vulpecuila) with cauda epididymal sperm to determine if sperm could penetrate the cumulus oophous and thereby remove the need to mechanically denude in vitro matured ovarian oocyctes, and if sperm-zona binding would occur under these conditions. No fertilisation or sperm-zona pellucida binding took place. Some spermatozoa within the cumulus oophorus layer were phagocytosed.
Publisher: Oxford University Press (OUP)
Date: 28-05-2010
Abstract: Accumulating evidence indicates that damage to the adult mammalian brain evokes an array of adaptive cellular responses and may retain a capacity for structural plasticity. We have investigated the cellular and architectural alterations following focal experimental brain injury, as well as the specific capacity for structural remodeling of neuronal processes in a subset of cortical interneurons. Focal acute injury was induced by transient insertion of a needle into the neocortex of anesthetized adult male Hooded-Wistar rats and thy1 green fluorescent protein (GFP) mice. Immunohistochemical, electron microscopy, and bromodeoxyuridine cell proliferation studies demonstrated an active and evolving response of the brain to injury, indicating astrocytic but not neuronal proliferation. Immunolabeling for the neuron-specific markers phosphorylated neurofilaments, α-internexin and calretinin at 7 days post injury (DPI) indicated phosphorylated neurofilaments and α-internexin but not calretinin immunopositive axonal sprouts within the injury site. However, quantitative studies indicated a significant realignment of horizontally projecting dendrites of calretinin-labeled interneurons at 14 DPI. This remodeling was specific to calretinin immunopositive interneurons and did not occur in a subpopulation of pyramidal neurons expressing GFP in the injured mouse cortex. These data show that subclasses of cortical interneurons are capable of adaptive structural remodeling.
No related grants have been discovered for Jamie Chapman.