Evaluation of platelet function screening tests to detect platelet procoagulant deficiency in dogs with Scott syndrome

Background: Clinical diagnosis of platelet dysfunction is complex and technically challenging. The wide repertoire of platelet responses requires a test panel to assess different parameters of platelet reactivity. While “global” hemostasis analyzers and whole blood assays have potential for testing platelet function, their ability to evaluate platelet procoagulant activity is ill‐defined. Objectives: The aim of this study was to determine whether platelet procoagulant deficiency, the pathophysiologic defect of Scott syndrome, could be detected in point‐of‐care and whole blood assays. Methods: Study subjects were 4 Scott syndrome‐affected German Shepherds and 8 control dogs. We evaluated 2 point‐of‐care instruments: the platelet function analyzer (PFA‐100) and thromboelastograph (TEG). TEG analysis was performed on recalcified citrated whole blood with and without tissue‐factor activation. A whole blood flow cytometric assay was configured to detect thrombin‐induced platelet P‐selectin expression and platelet‐derived microparticle release. Cytometric samples were analyzed after 1 hour and 1 day of storage. Results: We found no significant differences between Scott and control dogs in PFA‐100 COL/ADP closure times or in any TEG parameter in tissue‐factor–activated samples. In nonactivated samples, mean clotting time (K) and time to maximal rate of thrombus generation were significantly prolonged in Scott dogs; however, values overlapped with those of control dogs. Cytometric analysis of samples from Scott dogs showed significantly diminished platelet‐derived microparticle release. Samples from all dogs reanalyzed after 1 day of storage had nonspecific increases in basal P‐selectin expression and vesiculation. Conclusion: A whole blood cytometric assay to detect stimulated platelet microparticle release can be used to screen for Scott syndrome. However, platelet activation artifacts preclude overnight storage for next‐day analysis.     

Arabidopsis H+-PPase AVP1 regulates auxin-mediated organ development

The transport of auxin controls developmental events in plants. Here, we report that in addition to maintaining vacuolar pH, the H+-pyrophosphatase, AVP1, controls auxin transport and consequently auxin-dependent development. AVP1 overexpression results in increased cell division at the onset of organ formation, hyperplasia, and increased auxin transport. In contrast, avp1-1 null mutants have severely disrupted root and shoot development and reduced auxin transport. Changes in the expression of AVP1 affect the distribution and abundance of the P-adenosine triphosphatase and Pinformed 1 auxin efflux facilitator, two proteins implicated in auxin distribution. Thus, AVP1 facilitates the auxin fluxes that regulate organogenesis.     

Effects of serine palmitoyltransferase inhibition by myriocin in ad libitum-fed and nutrient-restricted ewes

The fungal isolate myriocin inhibits serine palmitoyltransferase and de novo ceramide synthesis in rodents; however, the effects of myriocin on ceramide concentrations and metabolism have not been previously investigated in ruminants. In our study, 12 non-lactating crossbred ewes received an intravenous bolus of myriocin (0, 0.1, 0.3, or 1.0 mg/kg/body weight [BW]; CON, LOW, MOD, or HIGH) every 48 h for 17 d. Ewes consumed a high-energy diet from day 1 to 14 and were nutrient-restricted (straw only) from day 15 to 17. Blood was collected preprandial and at 1, 6, and 12 h relative to bolus and nutrient restriction. Tissues were collected following euthanasia on day 17. Plasma was analyzed for free fatty acids (FFAs), glucose, and insulin. Plasma and tissue ceramides were quantified using mass spectrometry. HIGH selectively decreased metabolizable energy intake, BW, and plasma insulin, and increased plasma FFA (Dose, P < 0.05). Myriocin linearly decreased plasma very-long-chain (VLC) ceramide and dihydroceramide (DHCer) by day 13 (Linear, P < 0.05). During nutrient restriction, fold-change in FFA was lower with increasing dose (P < 0.05). Nutrient restriction increased plasma C16:0-Cer, an effect suppressed by MOD and HIGH (Dose × Time, P < 0.05). Myriocin linearly decreased most ceramide and DHCer species in the liver and omental and mesenteric adipose, VLC ceramide and DHCer in the pancreas, and C18:0-Cer in skeletal muscle and subcutaneous adipose tissue (Linear, P ≤ 0.05). We conclude that the intravenous delivery of 0.3 mg of myriocin/kg of BW/48 h decreases circulating and tissue ceramide without modifying energy intake in ruminants.     

Growth and Development Symposium: Impacts of inflammation on cattle growth and carcass merit

Inflammation caused by bovine respiratory disease (BRD) continues to be one of the greatest challenges facing beef cattle producers and feedlot managers. Inflammation decreases DMI, ADG, and G:F in feedlot calves, decreasing growth rate and increasing days on feed, which results in economic losses during the feeding period. During the past decade, marketing of feedlot animals has changed from selling cattle on a live basis to a grid-based marketing system. When cattle are marketed on a live basis, the economic effects of BRD stop at increased health cost and decreased feedlot performance, carcass weight, and death loss. However, when cattle are marketed in a grid-based system, inflammation has the potential to also affect carcass cutability and quality. The effects of inflammation on feedlot cattle in regards to performance are well understood; however, specific effects on cattle growth and ultimately carcass merit are not as well described. Recent studies in feedlot cattle have indicated that the incidence of BRD decreases both HCW and marbling; however, mechanisms are not understood. Research in other species has demonstrated that during the acute phase response, pro-inflammatory cytokines promote skeletal muscle catabolism to supply AA and energy substrates for immune tissues. Further, during this early immune response, the liver changes its metabolic priorities to the production of acute phase proteins for use in host defense. Together these dramatic shifts in systemic metabolism may explain the detrimental effects on performance and carcass traits commonly associated with BRD in feedlot calves. Moreover, recent studies relative to human health have revealed complex multilevel interactions between the metabolic and immune systems, and highlighted inflammation as being a significant contributor to major metabolic diseases. The objective of this paper is to review data to help explain the economical and physiological effects of inflammation on cattle growth and carcass merit.     

A trans-disciplinary study on the health risks of cryptosporidiosis from dairy systems in Dagoretti,Nairobi, Kenya: study background and farming system characteristics

This paper characterises the dairy farming system in Dagoretti, Nairobi. Characterisation was part of a broader ecohealth project to estimate the prevalence and risk of cryptosporidiosis and develop risk mitigation strategies. In the project a trans-disciplinary team addressed epidemiological, socioeconomic, environmental and policy aspects of cryptosporidiosis, an emerging zoonosis. This paper also provides background and describes sampling methods for the wider project. Three hundred dairy households were probabilistically sampled from a sampling frame of all dairy households in five of the six locations of Dagoretti, one of the eight districts of Nairobi Province. Randomly selected households identified 100 non-dairy-keeping households who also took part in the study. A household questionnaire was developed, pre-tested and administered in the dry and wet seasons of 2006. An additional study on livelihood and economic benefits of dairying took place with 100 dairy farmers randomly selected from the 300 farms (as well as 40 non-dairy neighbours as a control group), and a risk-targeted survey of environmental contamination with Cryptosporidium was conducted with 20 farmers randomly selected from the 29 farmers in the wider survey who were considered at high risk because of farming system. We found that around 1 in 80 urban households kept dairy cattle with an average of three cattle per household. Cross-breeds of exotic and local cattle predominate. Heads of dairy-keeping households were significantly less educated than the heads of non-dairy neighbours, had lived in Dagoretti for significantly longer and had significantly larger households. There was a high turnover of 10 % of the cattle population in the 3-month period of the study. Cattle were zero grazed, but productivity parameters were sub-optimal as were hygiene and husbandry practices. In conclusion, dairy keeping is a minor activity in urban Nairobi but important to households involved and their community. Ecohealth approaches are well suited to tackling the complex problem of assessing and managing emerging zoonoses in urban settings.     

Participatory probabilistic assessment of the risk to human health associated with cryptosporidiosis from urban dairying in Dagoretti,Nairobi, Kenya

We carried out a participatory risk assessment to estimate the risk (negative consequences and their likelihood) from zoonotic Cryptosporidium originating in dairy farms in urban Dagoretti, Nairobi to dairy farm households and their neighbours. We selected 20 households at high risk for Cryptosporidium from a larger sample of 300 dairy households in Dagoretti based on risk factors present. We then conducted a participatory mapping of the flow of the hazard from its origin (cattle) to human potential victims. This showed three main exposure pathways (food and water borne, occupational and recreational). This was used to develop a fault tree model which we parameterised using information from the study and literature. A stochastic simulation was used to estimate the probability of exposure to zoonotic cryptosporidiosis originating from urban dairying. Around 6 % of environmental samples were positive for Cryptosporidium. Probability of exposure to Cryptosporidium from dairy cattle ranged from 0.0055 for people with clinical acquired immunodeficiency syndrome in non-dairy households to 0.0102 for children under 5 years from dairy households. Most of the estimated health burden was born by children. Although dairy cattle are the source of Cryptosporidium, the model suggests consumption of vegetables is a greater source of risk than consumption of milk. In conclusion, by combining participatory methods with quantitative microbial risk assessment, we were able to rapidly, and with appropriate ‘imprecision’, investigate health risk to communities from Cryptosporidium and identify the most vulnerable groups and the most risky practices.     

A trans-disciplinary study on the health risks of cryptosporidiosis from dairy systems in Dagoretti, Nairobi, Kenya: study background and farming system characteristics

This paper characterises the dairy farming system in Dagoretti, Nairobi. Characterisation was part of a broader ecohealth project to estimate the prevalence and risk of cryptosporidiosis and develop risk mitigation strategies. In the project a trans-disciplinary team addressed epidemiological, socioeconomic, environmental and policy aspects of cryptosporidiosis, an emerging zoonosis. This paper also provides background and describes sampling methods for the wider project. Three hundred dairy households were probabilistically sampled from a sampling frame of all dairy households in five of the six locations of Dagoretti, one of the eight districts of Nairobi Province. Randomly selected households identified 100 non-dairy-keeping households who also took part in the study. A household questionnaire was developed, pre-tested and administered in the dry and wet seasons of 2006. An additional study on livelihood and economic benefits of dairying took place with 100 dairy farmers randomly selected from the 300 farms (as well as 40 non-dairy neighbours as a control group), and a risk-targeted survey of environmental contamination with Cryptosporidium was conducted with 20 farmers randomly selected from the 29 farmers in the wider survey who were considered at high risk because of farming system. We found that around 1 in 80 urban households kept dairy cattle with an average of three cattle per household. Cross-breeds of exotic and local cattle predominate. Heads of dairy-keeping households were significantly less educated than the heads of non-dairy neighbours, had lived in Dagoretti for significantly longer and had significantly larger households. There was a high turnover of 10?% of the cattle population in the 3-month period of the study. Cattle were zero grazed, but productivity parameters were sub-optimal as were hygiene and husbandry practices. In conclusion, dairy keeping is a minor activity in urban Nairobi but important to households involved and their community. Ecohealth approaches are well suited to tackling the complex problem of assessing and managing emerging zoonoses in urban settings.     

The effect of current grain feeding practices on hindgut starch fermentation and acidosis in the Australian racing Thoroughbred

A survey of 72 thoroughbred trainers in several regions of NSW was conducted to better define current grain feeding practices, and the risks involved with grain feeding in the Australian thoroughbred racing industry. Results from the survey indicate that horses in the industry are currently being fed an average of 7.3 +/- 0.23 kg of grain concentrate per day, with oats, commercial pre-mixed diets and corn most commonly used. The feeding of extruded, micronised and steam flaked grains was uncommon. The results of grain and faecal sample analyses conducted during the survey indicate that incomplete starch digestion in the equine small intestine and subsequent hindgut starch fermentation and low hindgut pH are common. These observations quantify the adverse impact of current grain feeding practices on faecal measures of gut health and demonstrate that when selecting grains for use in the thoroughbred racehorse, greater emphasis should be placed on the starch digestibility characteristics of grains.     

Electrolyte abnormalities induced by hypertonic phosphate enemas in two cats

Severe electrolyte disturbances developed after the administration of hypertonic phosphate enemas in 2 chronically obstipated cats. Hyperphosphatemia, hypernatremia, and hypocalcemia were detected in both cats. Physical findings included weakness, anxiety, tachycardia, hypothermia, and dehydration. Intravenous fluid and electrolyte therapy led to prompt, dramatic improvement in both cats. Although well tolerated by most healthy animals, hypertonic phosphate enemas should be avoided in small animals, especially those that are dehydrated, severely obstipated, or suffering from renal or colonic disease.     

TREATMENT OF OVINE ANNUAL RYEGRASS TOXICITY WITH CHLORDIAZEPOXIDE

The results of pen trials indicate that sheep affected by annual ryegrass toxicity can be treated successfully with chlordiazepoxide. In the first experiment, 87% of chlordiazepoxide-treated animals survived a lethal dose of toxic ryegrass. In the second experiment, 90% of chlordiazepoxide treated animals survived compared with a 10% recovery of control animals.