Antigen presenting cells in mucosal sites of veterinary species

The ability of antigen presenting cells, in particular dendritic cells, to integrate a variety of environmental signals, together with their ability to respond appropriately by initiating either tolerance or defensive immune responses make them cells of particular relevance and importance in the mucosal environment. They have been demonstrated in a variety of mucosal tissues in veterinary species and have been characterized to varying degrees, showing that fundamental immunological principles apply throughout all species, but also highlighting some species differences. A major advantage of carrying out immunological research in veterinary species is their size: it is possible to cannulate lymphatic ducts and obtain information about cell migration between different tissues. It is also possible to obtain pure populations of relatively rare cell types such as the plasmacytoid dendritic cells or mucosal dendritic cells ex vivo for the study of immune responses to diseases in their natural host and for other thorough functional studies. Two major myeloid antigen presenting cell (APC) (dendritic cells, DC) cell populations have been described in gut draining lymph and other mucosal sites in ruminants and pigs, characterised by the presence or absence of surface molecules, their enzyme profiles, their ability to phagocytose and their different potential as APC. There is evidence that one of these subsets has migrated from the diffuse mucosal tissue, where it is found as a phagocytic as well as stimulatory APC population, which in turn may be derived from blood macrophages. In addition, the presence and role in viral infection of the IFN-alpha producing plasmacytoid DC in mucosal tissue is discussed, based on studies in pigs.     

A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite

Background

Anaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA) in humans and tick-borne fever (TBF) in ruminants. The bacterium invades and replicates in phagocytes, especially in polymorphonuclear granulocytes.

Methods

In the present study, skin biopsies and ticks (Ixodes ricinus) were collected from tick feeding lesions on 38 grazing lambs between two and three weeks after access to pastures. The histopathological changes associated with tick bites and A. phagocytophilum infection, were described. In addition the skin biopsies were examined by immunohistochemistry. Furthermore, samples from blood, skin biopsies and ticks were examined by serology, PCR amplification of msp2 (p44), genotyping of rrs (16S rRNA) variants, and compared with the results obtained from histological and immunohistochemical investigations.

Results

Tick bites were associated with chronic and hyperplastic inflammatory skin lesions in this study. A. phagocytophilum present in skin lesions were mainly associated with neutrophils and macrophages. Bacteria were occasionally observed in the Tunica media and Tunica adventitia of small vessels, but were rarely found in association with endothelial cells. PCR and genotyping of organisms present in blood, ticks and skin biopsies suggested a haematogenous and a local spread of organisms at the tick attachment sites.

Conclusions

The present study describes different aspects of A. phagocytophilum infection at the site of tick bite, and indicates that A. phagocytophilum rarely associates with endothelium during the early pathogenesis of infection.     

Sweet blue lupin (Lupinus angustifolius L.) seed as a substitute for concentrate mix supplement in the diets of yearling washera rams fed on natural pasture hay as basal diet in Ethiopia

In the mixed crop-livestock farming system of Ethiopia where crop residues are the major feed resources and concentrate supplement feeds are not common, home-grown legume protein sources can help to minimise the feed problem. A 69-day feeding experiment on sheep was conducted to evaluate the potential of sweet blue lupin (Lupinus angustifolius L.) cultivar Sanabor seed as a substitute for commercial concentrate supplement. Thirty yearling male intact Washera sheep with initial body weight of 21 ± 1.38 kg (mean ± SD) were used. The design was a randomised complete block design with six replications. The five experimental supplement feeds were 453 g concentrate (T1), 342 g concentrate + 74 g lupin seed (T2), 228 g concentrate + 147 g lupin seed (T3), 116 g concentrate + 219 g lupin seed (T4) and 290 g lupin seed (T5) in dry matter basis to supplement around 100 g crude protein per day per animal. There were significant differences (P < 0.05) in total dry matter, crude protein, ash and organic matter intakes among treatments. The average daily body weight gain for T1, T2, T3, T4 and T5 was 91, 79, 79, 87 and 74 g/day, respectively, and this difference was not significant (P > 0.05). It was concluded that blue lupin seed has a potential to substitute the commercial concentrate supplement feed in Ethiopia.     

Adrenal function in cats with hyperthyroidism

Adrenal function may be altered in animals with hyperthyroidism. The aim of the study was to assess adrenal function of hyperthyroid cats (n = 17) compared to healthy cats (n = 18) and cats with chronic diseases (n = 18). Adrenal function was evaluated by adrenocorticotropic hormone (ACTH) stimulation test and the urinary cortisol to creatinine ratio (UCCR) was determined. Length and width of both adrenal glands were measured via ultrasound. Hyperthyroid cats had significantly higher cortisol levels before and after stimulation with ACTH than the other groups. However, the UCCR was not elevated in hyperthyroid cats. The size of the adrenal glands of hyperthyroid cats was not significantly different from the size of those of healthy cats. The results indicate that cats with hyperthyroidism have a higher cortisol secretory capacity in a hospital setting. The normal size of the adrenal glands suggests that cortisol levels may not be increased permanently.     

Neospora caninum and Waddlia chondrophila strain 2032/99 in a septic stillborn calf

Characteristics of an intracellularly growing micro-organism isolated from an aborted bovine foetus are described. The organism replicated within cytoplasmic vacuoles, was resistant to penicillin and exhibited structural characteristics compatible with Waddlia chondrophila. An ELISA specific for Chlamydia spp., immunofluorescence tests using antibodies directed against Chlamydia spp. or Simkania negevensis, and PCR using Chlamydia-specific primers showed that the agent was distinct from Chlamydiae or S. negevensis. Determination of 16S and partial 23S ribosomal RNA gene sequences in combination with the PCR results and the morphological, antigenic and developmental characteristics provided evidence that the isolate 2032/99 can be classified as W. chondrophila or a closely related organism.     

Serum concentrations of keratan sulfate,osteocalcin, and pyridinoline crosslinks after oral administration of glucosamine to standardbred horses during race training

OBJECTIVE: To determine the effects of orally administered glucosamine on concentrations of markers of bone and cartilage metabolism in Standardbred horses during race training. ANIMALS: Twenty 16- to 20-month-old Standardbreds beginning race training. PROCEDURE: Horses were randomly assigned to 2 groups. One group received glucosamine hydrochloride (4 g, PO, q 12 h), and the second (control) group received glucose (4 g, PO, q 12 h). Serum samples were obtained prior to onset of the study (baseline) and at regular intervals for 48 weeks for determination of concentrations of keratan sulfate (KS), osteocalcin (OC), and pyridinoline crosslinks (PYD). RESULTS: Osteocalcin concentrations changed significantly with time; mean serum concentrations were significantly higher than baseline values for samples obtained at 24 to 48 weeks after onset of the study. Although a significant effect of time was observed for mean concentration of KS, concentrations did not differ significantly from baseline values at any time during the study when groups were analyzed separately. However, pooled analysis revealed significant increases of mean serum KS concentration at weeks 24 and 30. Significant changes in serum PYD concentrations were not detected. Oral administration of glucosamine did not significantly affect serum concentrations of any of the markers. CONCLUSIONS AND CLINICAL RELEVANCE: Increased serum OC in clinically normal Standardbreds during race training may reflect bone formation that accompanies adaptive remodeling of the appendicular skeleton. For these experimental conditions, glucosamine did not appear to exert a detectable influence on serum concentrations of these 3 markers of connective tissue metabolism.     

Collective management on communal grazing lands: Its impact on vegetation attributes and soil erosion in the upper Blue Nile basin,northwestern Ethiopia

Collective action, on communal grazing land, has evolved in the highlands of northwestern Ethiopia to mitigate the problems of feed shortage and land degradation due to overgrazing. The exercise is liked by farmers for improving the availability of natural pasture during the long dry season when other feed sources get depleted. However, large portions of the communal grazing lands are still managed under free grazing throughout the year. This study was undertaken in Maynet village in the upper Blue Nile basin, northwestern Ethiopia, to assess the impacts of three different types of grazing land management (GLM) and two slope gradients (<10%; 15–25%) on aboveground herbaceous biomass yield, ground cover, species richness, runoff, soil loss and soil bulk density of grazing lands. The GLMs include (a) freely open communal GLM, (b) restricted communal GLM – collective management of communal grazing land locally named as ‘yebere sar’ and (c) private holding GLM. Stocking density was more than carrying capacity of grazing lands across all GLMs. However, the extent of overstocking problem was exceptionally severe in freely open communal GLM. The interaction between GLM and slope was significant (P<0.05) for runoff, soil loss and runoff coefficient. The average runoff coefficient was close to 50% in freely open communal GLM on steeper slopes (15–25%). Freely open communal GLM on steeper slopes resulted in consistently highest cumulative runoff and soil loss amounting to 491 mm and 32 t/ha per year, respectively. Polynomial regression analysis showed that quadratic relationship (r²=0.87) existed between soil loss and runoff. But, soil loss was close to nil when runoff did not exceed 2 mm per rainfall event. As expected, restricted communal GLM appeared to reduce surface runoff by more than 40% and curb the rate of soil erosion by more than 50% compared to freely open communal GLM. Its vegetation cover persisted above 70% throughout the year, meeting the threshold level recommended to keep surface runoff and soil loss to minimum. Reducing the problem of overstocking and pasture resting in August–November are important components to improve ground cover and aboveground herbaceous biomass yield, which in turn reduce land degradation on grazing lands.     

Prevalence of subclinical mastitis and isolated udder pathogens in dairy cows in Southern Vietnam

Dairy production is not traditional in Vietnam. The farmers have little practical knowledge and udder health control is generally lacking. In order to give the farmers appropriate advice, knowledge about the distribution of udder pathogens is crucial. The aim of the study was to investigate the prevalence of sub-clinical mastitis and to identify udder pathogens isolated from smallholder dairy herds in Southern Vietnam. Twenty farms with a herd somatic cell count (SCC) ranging from low (≤400?×?10³?cells/mL) to high (>400?×?10³?cells/mL) were randomly selected. Milk samples were collected from 458 quarters of 115 clinically healthy cows. SCC was analyzed on farm by a portable cell counter. Bacteriological samples were taken using Mastistrip^© cassettes and sent to Sweden for examination. For all herds the mean herd SCC was 632?×?10³/mL milk. The prevalence of subclinical mastitis at quarter SCC basis was 63.2 % and at cow basis 88.6 %. Only 40 % of all cows were bacteriologically negative in all quarters. Streptococcus agalactiae was the most commonly found bacteria species, isolated from 96 of the 458 quarter samples, in 13 of the 20 farms. The results indicate pronounced subclinical mastitis problems among the dairy cows in this region mainly due to infections with S. agalactiae. The high prevalence of this highly contagious pathogen is probably attributable to the generally poor milking hygiene and low awareness of proper measures to prevent occurrence and spread of udder infections. A strict, targeted action program for the herds in this area is required in order to lower the prevalence of subclinical mastitis.