The diagnosis of listeria encephalitis in ruminants using cultural and immunohistologic methods. II. Immunohistologic studies in formalin-fixed paraffin sections]

The unlabelled peroxidase-antiperoxidase (PAP)-technique was compared with the avidin-biotin-peroxidase-complex (ABC)-technique in the identification of Listeria antigen in formalin-fixed paraffin sections of 58 ruminant brains, 44 of which showed histopathological lesions typical for listeric encephalitis. Rabbit hyperimmune serum, obtained by immunization with a Listeria monocytogenes strain of serotype 1/2 a, served as primary serum in the immunohistochemical investigations. The antiserum was tested for specificity using formalin-fixed smears of various bacterial species. Listeria antigen was demonstrated in 40 of the 44 brains with histopathological CNS alterations, as seen in listeriosis, using the ABC method, whereas their identification with the PAP method only succeeded in 34 of the brains. Despite the higher dilution of the primary antibody, the ABC method distinguished itself further, in comparison with the PAP method, through more intense immunohistochemical staining of Listeria antigen. Listeria spp, could be isolated from 46 of 52 brains, which were also examined bacteriologically. They could be isolated from 14 brains, which showed no histopathological lesions indicative of listeriosis. In contrast to this, Listeria antigen was only detected immunohistologically in brains with typical histological listeric CNS alterations. In three cases the presumptive histological diagnosis could not be confirmed immunohistologically.     

Glucosinolates in mixed-packaged mini broccoli and mini cauliflower under modified atmosphere

Contents of total and individual glucosinolates of mini broccoli cv. Milady and mini cauliflower cv. Clarke were assessed to determine the effect of modified atmosphere packaging on postharvest glucosinolate dynamics of mixed mini Brassica vegetables. Therefore, mixed-packaged mini broccoli and mini cauliflower stored in food trays sealed with two different microperforated biaxial-oriented polypropylene films for up to 7 days at 8 degrees C were analyzed. The results indicate that modified atmosphere at 8% O2 + 14% CO2 was a suitable gaseous combination to maintain aliphatic and indole glucosinolates in mini broccoli for 7 days after an initial decrease at 4 days. In contrast, modified atmosphere at 1% O2 + 21% CO2 resulted in the best retention of indole glucosinolates of mini cauliflower for 7 days and also of aliphatic glucosinolates after an initial decrease at 4 days. Thus, to maintain glucosinolates and external appearance and to prevent off-odor, mini broccoli and mini cauliflower should be packed separately in suitable altered gas composition.     

The IgA system: a comparison of structure and function in different species

The predominant immunoglobulin isotype on most mucosal surfaces is secretory immunoglobulin A (SIgA), a polypeptide complex comprising two IgA monomers, the connecting J chain, and the secretory component. The molecular stability and strong anti-inflammatory properties make SIgA particularly well suited to provide protective immunity to the vulnerable mucosal surfaces by preventing invasion of inhaled and ingested pathogens. In contrast to SIgA, IgA in serum functions as an inflammatory antibody through interaction with FcalphaR on immune effector cells. Although IgA appears to share common features and protective functions in different species, significant variations exist within the IgA systems of different species. This review will give an overview of the basic concepts underlying mucosal IgA defence which will focus on the variations present among species in structure, antibody repertoire development, pIgR-mediated transport, colostral IgA content, hepatobiliary transport, and function with particular emphasis on the IgA system of the pig and dog. These interspecies variations emphasise the importance of elucidating and analysing the IgA system within the immune system of the species of interest rather than inferring roles from conclusions made in human and mouse studies.     

Sulfate burial constraints on the Phanerozoic sulfur cycle

The sulfur cycle influences the respiration of sedimentary organic matter, the oxidation state of the atmosphere and oceans, and the composition of seawater. However, the factors governing the major sulfur fluxes between seawater and sedimentary reservoirs remain incompletely understood. Using macrostratigraphic data, we quantified sulfate evaporite burial fluxes through Phanerozoic time. Approximately half of the modern riverine sulfate flux comes from weathering of recently deposited evaporites. Rates of sulfate burial are unsteady and linked to changes in the area of marine environments suitable for evaporite formation and preservation. By contrast, rates of pyrite burial and weathering are higher, less variable, and largely balanced, highlighting a greater role of the sulfur cycle in regulating atmospheric oxygen.     

Presumptive primary central nervous system T cell lymphoma in a deer (Capreolus capreolus)

This report describes the morphological and immunohistochemical findings in an approximately 7-year old wild European roe deer (Capreolus capreolus) with an infiltrative primary central nervous system T cell lymphoma. The roebuck had lost its timidity and was shot by a hunter. It was submitted for necropsy to exclude rabies. Gross examination revealed besides a verminous pneumonia no abnormal findings. Histologically, there was a highly cellular, not well demarcated, unencapsulated, and infiltrative neoplasm within basal parts of the brain. Tumour cells were round, up to 15μm in diameter and loosely arranged in sheets with a multifocally predominant perivascular infiltration. Immunohistochemically, tumour cells were positive for CD3 antigen. Whilst secondary lymphomas of the central nervous system emerge by metastatic seeding of tumour cells, primary lymphomas originate within the neuroparenchyma. This is the first report of a primary central nervous system lymphoma in an European roe deer.     

Latent class analysis of the diagnostic characteristics of PCR and conventional bacteriological culture in diagnosing intramammary infections caused by Staphylococcus aureus in dairy cows at dry off

Background

Staphylococcus aureus is one of the most common causes of intramammary infections in dairy cows at dry off. Reliable identification is important for disease management on herd level and for antimicrobial treatment of infected animals. Our objective was to evaluate the test characteristics of PathoProof ™ Mastitis PCR Assay and bacteriological culture (BC) in diagnosing bovine intramammary infections caused by S. aureus at dry off at different PCR cycle threshold (Ct)-value cut-offs.

Methods

Sterile quarter samples and non-sterile composite samples from 140 animals in seven herds were collected in connection with the dairy herd improvement (DHI) milk recording. All quarter samples were analyzed using BC whereas all composite samples were analyzed with PathoProof ™ Mastitis PCR Assay. Latent class analysis was used to estimate test properties for PCR and BC in the absence of a perfect reference test. The population was divided into two geographically divided subpopulations and the Hui-Walter 2-test 2-populations model applied to estimate Se, Sp for the two tests, and prevalence for the two subpopulations.

Results

The Se for PCR increased with increasing Ct-value cut-off, accompanied by a small decrease in Sp. For BC the Se decreased and Sp increased with increasing Ct-value cut-off. Most optimal test estimates for the real-time PCR assay were at a Ct-value cut-off of 37; 0.93 [95% posterior probability interval (PPI) 0.60-0.99] for Se and 0.95 [95% PPI 0.95-0.99] for Sp. At the same Ct-value cut-off, Se and Sp for BC were 0.83 [95% PPI 0.66-0.99] and 0.97 [95% PPI 0.91-0.99] respectively. Depending on the chosen PCR Ct-value cut-off, the prevalence in the subpopulations varied; the prevalence increased with increasing PCR Ct-value cut-offs.

Conclusion

Neither BC nor real-time PCR is a perfect test in detecting IMI in dairy cows at dry off. The changes in sensitivity and prevalence at different Ct-value cut-offs for both PCR and BC may indicate a change in the underlying disease definition. At low PCR Ct-value cut-offs the underlying disease definition may be a truly/heavily infected cow, whereas at higher PCR Ct-value cut-offs the disease definition may be a S. aureus positive cow.     

East Coast fever immunisation field trial in crossbred dairy cattle in Hanang and Handeni districts in northern Tanzania

East Coast fever (ECF) causes considerable mortality and production losses in the Tanzania smallholder dairy sector and limits the introduction of improved dairy breeds in areas where the disease is present. The infection and treatment method (ITM) was adopted by smallholder dairy farms for ECF immunisation in Hanang and Handeni districts of Tanzania. This study recorded incidence rates for ECF and other tick-borne diseases (TBDs) for ECF-immunised and non-immunised cattle between 1997 and 2000. Approximately 80% of smallholder households from both sites (n?=?167) participated in this longitudinal study, with immunisations carried out at the request of the livestock owners. Efficacy of ITM for preventing ECF cases in these crossbred dairy cattle was estimated at 97.6%, while that for preventing ECF deaths was 97.9%. One percent of the cattle developed clinical ECF as a result of immunisation. Since ECF immunisation permits a reduction in acaricide use, an increase in other TBDs is a potential concern. Sixty-three percent of farmers continued to use the same acaricide after immunisation, with 80% of these reducing the frequency of applications. Overall, 78% of farmers increased the acaricide application interval after immunisation beyond that recommended by the manufacturer, resulting in annual savings in the region of USD 4.77 per animal. No statistical difference was observed between the immunised and non-immunised animals in the incidence of non-ECF TBDs. However, immunised animals that succumbed to these diseases showed fewer case fatalities. ITM would therefore appear to be a suitable method for ECF control in Tanzania's smallholder dairy sector.