Saturday Creek

https://issuu.com/burwellm/docs/cirque_14_-_fullYe

Leaving Egypt

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Rising

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Care Package for Eva

Originally published in Cirque https://issuu.com/burwellm/docs/cirque_14_-_fullYe

Samantha's Births

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Analysis of Veterinary Drug Residues in Imported and Domestic Crawfish Using Liquid Chromatography—Mass Spectrometry

Aquaculture production has greatly increased over the past few decades, and will continue to grow as the world fisheries become overfished and demand for seafood increases. With increased production comes more intense cultivation methods and heavy use of formulated feeds that may contain veterinary drug residues. Currently no antibiotics are allowed in the U.S. for crawfish aquaculture; yet, detectable levels of various antibiotics have been found in imported seafood samples.The FDA is responsible for testing aquaculture products entering the United States, but only has the capabilities to test a minimal amount of those imports. Additionally, for crawfish there is only one published FDA method to test for chloramphenicol, and they have yet to publish a method to test for multiple veterinary drug residues. Therefore, the objective of this study was to develop a method that could test various antibiotics in commercially available frozen crawfish, and use that method to test imported and domestic crawfish. Crawfish were obtained from the Aquaculture Research Station at Louisiana State University, and were used as blank crawfish to validate a method to test for chloramphenicol, florfenicol, enrofloxacin, ciprofloxacin, and sarafloxacin using liquid chromatography—mass spectrometry. In short, the tissue was extracted with dilute acetic acid and acetonitrile with added sodium chloride. After centrifugation, the extract was evaporated to dryness with nitrogen and reconstituted in mobile phase. The extract was passed through a syringe and 0.2μm PVDF membrane filter into an auto-sampler vial. A Waters Acquity TQD LC/MS/MS operated in the positive and negative ion mode; ciprofloxacin, enrofloxacin, and sarafloxacin in positive ion mode, and florfenicol and chloramphenicol in negative ion mode. Results indicated acceptable method performance characteristics for selectivity, linearity, accuracy (recovery), precision (RSD), and MDL and LOQ. Though ciprofloxacin did show some of the lowest recoveries, and chloramphenicol did have quite high RSD values. Retail samples tested negative for most of the veterinary drug residues with the exception of chloramphenicol in one Louisiana brand at an average concentration of 0.91 ng/g, and in a Chinese brand at an average concentration of 0.52 ng/g

Treatment strategies for sheep scab:an economic model of farmer behaviour

Ovine psoroptic mange (sheep scab) is a debilitating and damaging condition caused by a hypersensitivity reaction to the faecal material of the parasitic mite Psoroptes ovis. Farmers incur costs from the use of prophylactic acaricides and, if their sheep become infected, they incur the costs of therapeutic treatment plus the economic loss from reduced stock growth, lower reproductive rate, wool loss and hide damage. The unwillingness of farmers to use routine prophylactic treatment has been cited as a primary cause of the growing incidence of sheep scab in the United Kingdom (UK) since the disease was deregulated in 1992. However, if farmers behave rationally from an economic perspective, the optimum strategy that they should adopt will depend on the risk of infection and the relative costs of prophylactic versus therapeutic treatment, plus potential losses. This calculation is also complicated by the fact that the risk of infection is increased if neighbours have scab and reduced if neighbours treat prophylactically. Hence, for any farmer, the risk of infection and optimum approach to treatment is also contingent on the behaviour of neighbours, particularly when common grazing is used. Here, the relative economic costs of different prophylactic treatment strategies are calculated for upland and lowland farmers and a game theory model is used to evaluate the relative costs for a farmer and his/her neighbour under different risk scenarios. The analysis shows that prophylaxis with organophosphate (OP) dipping is a cost effective strategy, but only for upland farmers where the risk of infection is high. In all other circumstances prophylaxis is not cost effective relative to reliance on reactive (therapeutic) treatment. Hence, farmers adopting a reactive treatment policy only, are behaving in an economically rational manner. Prophylaxis and cooperation only become economically rational if the risk of scab infection is considerably higher than the current national average, or the cost of treatment is lower. Should policy makers wish to reduce the national prevalence of scab, economic incentives such as subsidising the cost of acaricides or rigorously applied financial penalties, would be required to make prophylactic treatment economically appealing to individual farmers. However, such options incur their own infrastructure and implementation costs for central government

Detecting CO2-sensitive hemichannels in neurons in acute brain slices

This protocol provides two independent methods to functionally detect the neuronal expression of CO2-sensitive hemichannels. These hemichannels (consisting of connexins 26 or 30) are directly gated by CO2, independent of pH changes and until recently were thought to be only expressed by glia. This protocol outlines a method to change the concentration of CO2 without changing pH, using isohydric solutions and then utilizing this to detect opening and closing of functional hemichannels using whole-cell patch clamp recording and dye loading