Role of personal decontamination in preventing the spread of equine influenza

BACKGROUND

During the 2007 equine influenza (EI) outbreak, infected horses were quarantined at Morgan Park Recreational Grounds (MPRG) near Warwick, Queensland. Some individuals caring for horses were reported to have made return journeys between MPRG and home properties containing other horses during the time there was active infection at MPRG.

OBJECTIVE

A retrospective cohort study to assess the biosecurity and hygiene measures undertaken and their outcomes.

METHODS

All individuals recorded as being responsible for caring for one or more horses at MPRG, and who were also recorded on entry and exit logs at the gate to MPRG during the period of interest, and kept horses at their home property were contacted for a telephone questionnaire.

RESULTS

Of the 31 individuals identified, valid responses were obtained from 27 (87% response rate). Respondents had 2-25 horses at their home property, and 1-10 return trips were reported; 11 respondents reported contact with horses at home and provided information on biosecurity practices.

CONCLUSION

Although horses at some home properties became infected with EI, it appears unlikely that this was the result of spread from MPRG via horse handlers. Simple preventive measures based on personal decontamination and other biosecurity measures are considered likely to have prevented spread of infection from MPRG to other properties.

Imaging cortical lesions in multiple sclerosis with ultra-high-field magnetic resonance imaging

OBJECTIVE

To determine the sensitivity of T2*-weighted gradient-echo (T2*GRE) and inversion recovery turbo-field-echo (TFE) sequences for cortical multiple sclerosis lesions at 7 T.

DESIGN, SETTING, AND PARTICIPANTS

Autopsied brain tissue from individuals with multiple sclerosis was scanned with 3-dimensional T2*GRE and 3-dimensional inversion recovery white matter-attenuated TFE sequences at 7 T. Cortical lesions visible with either sequence were scored for each anatomical lesion type. Imaged brain tissue was then processed for immunohistochemical analysis, and cortical lesions were identified by labeling with antibody against myelin basic protein and CD68 for microglia. Magnetic resonance images were matched with corresponding histological sections and scored retrospectively to determine the sensitivity for each cortical lesion type. Main Outcome Measure Cortical lesion detection by 3-dimensional T2*GRE and white matter-attenuated TFE sequences.

RESULTS

The 3-dimensional T2*GRE and white matter-attenuated TFE sequences retrospectively detected 93% and 82% of all cortical lesions, respectively (with varying sensitivities for different lesion types). Lesion visibility was primarily determined by size as all undetected lesions were smaller than 1.1 mm at their smallest diameter. The T2*GRE images showed hypointense rings in some cortical lesions that corresponded with increased density of activated microglia.

CONCLUSIONS

Three-dimensional T2*GRE and white matter-attenuated TFE sequences at a 7-T field strength detect most cortical lesions in postmortem multiple sclerosis tissue. This study indicates the potential of T2*GRE and white matter-attenuated TFE sequences in ultra-high-field magnetic resonance imaging for cortical lesion detection in patients with multiple sclerosis.

Assessing the Impact of Suicide Exclusion Periods on Life Insurance

Background: We study the impact of suicide-exclusion periods, common in life insurance policies in Australia, on suicide and accidental death rates for life-insured individuals. If a life-insured individual dies by suicide during the period of suicide exclusion, commonly 13 months, the sum insured is not paid. Aims: We examine whether a suicide-exclusion period affects the timing of suicides. We also analyze whether accidental deaths are more prevalent during the suicide-exclusion period as life-insured individuals disguise their death by suicide. We assess the relationship between the insured sum and suicidal death rates. Methods: Crude and age-standardized rates of suicide, accidental death, and overall death, split by duration since the insured first bought their insurance policy, were computed. Results: There were significantly fewer suicides and no significant spike in the number of accidental deaths in the exclusion period for Australian life insurance data. More suicides, however, were detected for the first 2 years after the exclusion period. Higher insured sums are associated with higher rates of suicide. Conclusions: Adverse selection in Australian life insurance is exacerbated by including a suicide-exclusion period. Extension of the suicide-exclusion period to 3 years may prevent some “insurance-induced” suicides – a rationale for this conclusion is given.

Dysmyelinated axons in shiverer mice are highly vulnerable to alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor-mediated toxicity

Glutamate excitotoxicity plays a role in white matter injury in many neurological diseases. Oligodendrocytes in particular are highly vulnerable to excitotoxicity, mediated through activation of AMPA/kainate receptors. Myelin may also be injured independently via NMDA (N-methyl-D-aspartic acid) receptors located on peripheral oligodendroglial processes. Central axons are susceptible to glutamate receptor activation in vivo, but it is unclear whether this is mediated directly by activation of receptors expressed on axons, or indirectly through glutamate toxicity of myelin or neighboring glial cells. We examined axonal vulnerability in mice deficient in myelin basic protein (shiverer), also expressing yellow fluorescent protein (YFP) in a subset of axons. YFP fluorescence, EM, and mouse behavior were assessed 24 h after microstereotactical injections of S-AMPA or NMDA into lumbar dorsal columns. S-AMPA injection led to impaired rotarod performance and widespread axonal degeneration and was more pronounced in shiverer mice than controls. In contrast, NMDA injection did not cause axonal injury or behavioral changes in either group. These results indicate that spinal cord axons in vivo are vulnerable to toxicity mediated by AMPA but not NMDA receptors. The presence of compact myelin is not required for excitotoxic axon damage, and its absence may increase vulnerability. Further understanding of AMPA receptor-mediated axonal toxicity may provide new targets for neuroprotective therapy in WM diseases.

Glutamate uptake by oligodendrocytes: Implications for excitotoxicity in multiple sclerosis

BACKGROUND

Excitotoxic damage is a common pathologic event in a number of neurologic diseases occurring after accumulation of excess extracellular glutamate in the CNS and subsequent overstimulation of glutamate receptors. In gray matter, astrocytes take up synaptically released glutamate and are thus key cells in maintaining glutamate homeostasis. In white matter, oligodendrocytes have been shown to express glutamate transporters, but their role in extracellular glutamate removal is unclear.

OBJECTIVE

To investigate whether cultured human fetal oligodendrocytes functionally express the main glutamate transporters EAAT-1 and EAAT-2.

METHODS

Cultures of fetal human oligodendrocytes were examined by immunocytochemistry and [3H]glutamate uptake, and the findings were correlated with glutamate transporter expression in normal and multiple sclerosis (MS) CNS tissue.

RESULTS

Both EAAT-1 and EAAT-2 were expressed by human oligodendrocytes in vitro. Incubation of oligodendrocytes with the proinflammatory cytokine tumor necrosis factor-alpha (TNFalpha) reduced EAAT-1 expression and inhibited glutamate uptake by >75%. Furthermore, in normal human white matter, oligodendrocytes were found to be the predominant cells to express EAAT-1 and EAAT-2, both at the mRNA and at the protein level. A small number of astrocytes in white matter expressed these receptors, more so EAAT-1 than EAAT-2. In MS white matter, oligodendrocytes lost expression of EAAT-1 and EAAT-2 receptors in the lesion vicinity.

CONCLUSIONS

Oligodendrocytes appear to be predominant cells for glutamate clearance in human white matter. Glutamate receptor expression and glutamate removal were defective in MS white matter, possibly mediated by TNFalpha, changes that might underlie high extracellular glutamate and an increased risk for glutamate excitotoxicity.

Experimental autoimmune encephalomyelitis (EAE) in CCR2(-/-) mice: susceptibility in multiple strains

Chemokines are low molecular weight cytokines which act as chemoattractants for infiltrating cells bearing appropriate receptors (CCR) to sites of inflammation. It has been proposed that CCR2 on monocytes is responsible for their recruitment into the central nervous system (CNS) in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis, and two previous reports have described resistance of CCR2(-/-) mice to EAE. The present study examined three different mouse strains with CCR2 deletions for susceptibility to EAE. Animals were studied up to 4 months post-sensitization and were examined by neuropathology, RNase protection assay, in situ hybridization, and in vitro assays. All three strains were found to be susceptible to EAE: C57BL/6 x J129 and Balb c strains, 100%; and C57BL/6, 67%. Unusual in CNS lesions of CCR2(-/-) mice was an overabundance of neutrophils versus monocytes in wild-type animals. An attempt of the immune system to develop compensatory mechanisms for the lack of CCR2 was evidenced by a corresponding increase in mRNA for other chemokines and CCR. Inasmuch as neutrophils replaced monocytes and led to demyelination, our findings support the concept that promiscuity of chemokines and CCR was able to surmount the deletion of CCR2, still resulting in full expression of this autoimmune disease.

Composted recycled organic matter suppresses soil-borne diseases of field crops

• Suppression of soil-borne diseases of horticultural crops by composts has been attributed to the activities of antagonistic microorganisms. The potential for abiotic disease suppression in field-grown crops was explored using glasshouse-based bio-assays for five pathogens of agricultural crops and eight formulations of recycled organic matter compost. • The effects of compost formulation and postmaturation processing were investigated by comparing disease severity on recycled organic matter composts with a commercial seedling compost. Comparisons were made within native and autoclaved series of composts. Autoclaving perturbed compost chemistry without the addition of other materials. • The severity of autoclaving-induced changes to compost chemistry were related to formulation and processing issues. Extractable carbon content, nitrate-N content and pH all contributed to the suppressive capacity of recycled organic matter composts. There may also be a biotic component to the suppression observed. • For each pathogen the influential chemical characteristics of suppressive composts were the same as those identified for soils in other studies. There is potential for the suppressive capacity of recycled organic matter composts to be improved.

Multiple sclerosis: altered glutamate homeostasis in lesions correlates with oligodendrocyte and axonal damage

Glutamate excitotoxicity, recently demonstrated in an animal model of multiple sclerosis (MS), is evoked by altered glutamate homeostasis. In the present study, we investigated the major regulating factors in glutamate excitotoxicity by immunohistochemistry in MS and control white matter with markers for glutamate production (glutaminase), glutamate transport (GLAST, GLT-1 and EAAT-1), glutamate metabolism (glutamate dehydrogenase [GDH] and glutamine synthetase [GS]), axonal damage (SMI 32) and CNS cell types. Active MS lesions showed high-level glutaminase expression in macrophages and microglia in close proximity to dystrophic axons. Correlation between glutaminase expression and axonal damage was confirmed experimentally in animals. White matter from other inflammatory neurologic diseases displayed glutaminase reactivity, whereas normals and noninflammatory conditions showed none. All three glutamate transporters were expressed robustly, mainly on oligodendrocytes, in normal, control and MS white matter, except for GLT-1, which showed low-level expression around active MS lesions. GS and GDH were present in oligodendrocytes in normal and non-MS white matter but were absent from both active and chronic silent MS lesions, suggesting lasting metabolic impediments. Thus, imbalanced glutamate homeostasis contributes to axonal and oligodendroglial pathology in MS. Manipulation of this imbalance may have therapeutic import.

Glutamate excitotoxicity--a mechanism for axonal damage and oligodendrocyte death in Multiple Sclerosis?

Glutamate excitotoxicity mediated by the AMPA/kainate-type of glutamate receptors is known not only to damage neurons but also the myelin-producing cell of the central nervous system (CNS), the oligodendrocyte. In Multiple Sclerosis (MS), myelin, oligodendrocytes and axons are lost or damaged as a result of an inflammatory attack on the CNS. Activated immune cells produce glutamate in large quantities by deamidating glutamine via glutaminase. Thus, we hypothesized that during inflammation in MS, glutamate excitotoxicity may contribute to the lesion. This was addressed by treating mice sensitized to develop acute experimental autoimmune encephalomyelitis (EAE) with an AMPA/kainate antagonist, NBQX. Treatment resulted in substantial amelioration of disease, increased oligodendrocyte survival and reduced axonal damage, as indicated by the levels of dephosphorylated neurofilament-H. Despite the clinical differences, NBQX-treatment had no effect on lesion size and did not reduce the degree of CNS inflammation. In addition, NBQX did not alter the proliferative activity of antigen-primed T cells in vitro, further indicating a lack of effect at the level of the immune system. In separate studies, infiltrating immune cells present in perivascular cuffs, commonly the site of entry for invading immune cells, were found to express glutaminase in abundance, supporting the production of glutamate in inflammatory lesions. Thus, glutamate excitotoxicity appears to be an important mechanism in autoimmune demyelination and its prevention with AMPA/kainate antagonists may prove to be an effective therapy for MS.

Insulin-like growth factor-1 fails to enhance central nervous system myelin repair during autoimmune demyelination

Previous studies have shown that insulin-like growth factor-1 (IGF-1) has beneficial effects, both clinically and histopathologically, on experimental autoimmune encephalomyelitis (EAE), although results vary depending on species and treatment regimen. The present study investigated whether IGF-1, delivered at different time points during the acute and chronic phases of adoptively transferred EAE in SJL mice, had the ability to affect or enhance myelin regeneration. Central nervous system tissue sampled at different stages of treatment was subjected to detailed neuropathological, immunocytochemical and molecular analysis. The results revealed some transient clinical amelioration and low level remyelination after IGF-1 administration during the acute phase of EAE. However, central nervous system tissue from acute phase treated animals sampled at chronic time points and from animals given IGF-1 during the chronic phase revealed no enhancing effect on remyelination in comparison to vehicle-treated controls. Examination of oligodendrocyte progenitor populations also revealed no differences between IGF-1- and vehicle-treated groups. At the cytokine level, the immunomodulatory molecules TGF-beta2 and TGF-beta3 displayed significant decreases that may have contributed to the transient nature of the effect of IGF-1 on EAE. Together with evidence from previous studies, it appears doubtful that IGF-1 is a good candidate for treatment in multiple sclerosis, for which EAE serves as a major model.

Novel Propionibacterium infection in cattle

OBJECTIVE

To describe four cases of infection in cattle, from geographically different places, with a presumptive new species of Propionibacterium, which causes granulomatous lesions in the head, thorax, abdomen, pelvic area and skin.

PROCEDURE

Gross lesions, ranging from 0.5 to 15 cm and detected during routine carcase inspection at the abattoir, were submitted to the laboratory for routine testing in the National Granuloma Submission Program. The bacterium isolated was identified using morphological characteristics, biochemical reactions, cell wall components, products of fermentation and 16S rRNA gene sequencing.

RESULTS

Gross lesions submitted for examination consisted of a fibrous outer capsule enclosing thick yellow pus-like material. A Gram-Glynn stain of the histological sections revealed colonies of Gram-positive, filamentous, branching bacteria. Bacteriological culture, cell wall analysis, biochemical reactions and 16S rRNA sequencing identified the organism as a Propionibacterium sp closely related to P cyclohexanicum and the P freudenreichii cluster.

CONCLUSION

This is the first report of a Propionibacterium sp closely related to P cyclohexanicum and the P freudenreichii cluster associated with extensive granulomatous lesions in cattle in Queensland. Sequencing data are suggestive of a previously undescribed species of the Propionibacterium genus.

Glutamate excitotoxicity in a model of multiple sclerosis

Glutamate excitotoxicity mediated by the AMPA/kainate type of glutamate receptors damages not only neurons but also the myelin-producing cell of the central nervous system, the oligodendrocyte. In multiple sclerosis, myelin, oligodendrocytes and some axons are lost as a result of an inflammatory attack on the central nervous system. Because glutamate is released in large quantities by activated immune cells, we expected that during inflammation in MS, glutamate excitotoxicity might contribute to the lesion. We addressed this by using the AMPA/kainate antagonist NBQX to treat mice sensitized for experimental autoimmune encephalomyelitis, a demyelinating model that mimics many of the clinical and pathologic features of multiple sclerosis. Treatment resulted in substantial amelioration of disease, increased oligodendrocyte survival and reduced dephosphorylation of neurofilament H, an indicator of axonal damage. Despite the clinical differences, treatment with NBQX had no effect on lesion size and did not reduce the degree of central nervous system inflammation. In addition, NBQX did not alter the proliferative activity of antigen-primed T cells in vitro, further indicating a lack of effect on the immune system. Thus, glutamate excitotoxicity seems to be an important mechanism in autoimmune demyelination, and its prevention with AMPA/kainate antagonists may prove to be an effective therapy for multiple sclerosis.

Neuregulin and erbB receptor expression in normal and diseased human white matter

Human white matter from non-neurologic cases, multiple sclerosis (MS) and other neurologic diseases (OND, inflammatory and non-inflammatory), was subjected to immunocytochemistry and Western blotting for expression of the neuregulin, glial growth factor-2 (GGF2), and its receptors, erbB2, erbB3 and erbB4. GGF2 has previously been shown to have mitogenic effects upon oligodendrocytes in vitro and an enhancing effect upon remyelination in animals with autoimmune demyelination. In all types of human white matter examined, expression of the ligand GGF2 and its three receptors was consistently found on oligodendrocytes, with higher levels being seen in cases of MS. Expression was also seen, albeit at lower levels, on astrocytes and microglial cells, the latter most commonly in MS and OND. In human lymph node tissue, some lymphocytes were positive for erbB2, erbB3 and erbB4. Western blots confirmed the presence of all three receptors in normal, MS and OND white matter. GGF2 and erbB receptor expression did not correlate with areas of remyelination and reactivity occurred throughout the tissue, with some increase in intensity at the edge of MS lesions. Examination of precursor oligodendrocyte immunoreactivity (with anti-PDGF-Ralpha and NG2), revealed widespread expression throughout both normal and diseased white matter. The presence of GGF2 and its receptors on oligodendrocytes and lymphocytes render this cell type a candidate for functional signaling via this pathway, perhaps in relationship to myelinating activity.

Histochemical and ultrastructural characterization of vacuoles and spherosomes as components of the lytic system in hyphae of the fungus Botrytis cinerea

An integrated approach to acid phosphatase (EC 3.1.3.2) histochemistry by the azo-dye and lead-capture ('Gomori') methods in phosphate-starved hyphae of the fungus Botrytis cinerea revealed strikingly different patterns of localization of activity staining. Reaction product formed with the azo-dye method was found in numerous small organelles (<0.5 microm diameter), which also accumulated the lipophilic dye Nile Red and mislocalized the formazan indicating mitochondrial succinate dehydrogenase activity. Such small organelles were stained only weakly and sporadically with the lead-capture method; instead, lead phosphate deposits were produced mainly in large vacuoles (up to 2.5 microm diam.), similar to those accumulating the vital dye Neutral Red. Additionally, acid phosphatase activity was detected in apical secretory vesicles with the lead-capture method but not with the azo-dye method. Ultrastructural studies by transmission electron microscopy confirmed the presence of large vacuoles which showed evidence of autophagic activity, and of small moderately osmiophilic organelles. The latter are considered to be spherosomes rather than lysosomes because of their weak reaction with the lead-capture method and their high lipid content. It is suggested that their apparently strong reaction with the azo-dye method is caused partly by false localization due to the lipophilic nature of the reaction product.