An evaluation of residual contamination by Clostridium botulinum in a trout farm following an outbreak of botulism in the fish stock

Abstract Following an outbreak of botulism in the fish stock of a British trout farm in 1980, a survey of the residual contamination of the farm was carried out. Commencing in November 1980, the farm was examined monthly for one year after the disease had been eliminated. A nearby unaffected farm was examined as a control. Examination of pond muds showed that the affected farm remained contaminated throughout the year, counts of Clostridium botulinum type E ranging from 1-800/g compared with counts at the control farm of 0.1-0.7/g. Both C. botulinum types B and E were found in the control farm, either singly or together in individual samples of pond mud. Fish taken from the affected farm in May and August of 1981 showed a 77.1 % (s.e. ±7.7) contamination by type E. Examination of the environs of the affected farm yielded C. botulinum in 36 of 60 samples of mud and soil using enrichment culture techniques. Clostridium botulinum type E predominated in muds, occurring in 26 of 28 samples taken from the waters supplying and by-passing the farm. In contrast, of the 32 soil samples tested from around the farm, eight yielded type B whereas only three contained type E.     

Real time monitoring of propofol blood concentration in ponies anaesthetized with propofol and ketamine

This study examined the pharmacokinetics of propofol by infusion in ponies using an analyser for the rapid measurement of propofol concentrations. The analyser (Pelorus 1000; Sphere Medical Ltd., Cambridge, UK) has a measurement cycle of approximately five minutes. Ten Welsh‐cross ponies (weighing 135–300 kg) undergoing minor procedures were studied after premedication with acepromazine 0.03 mg/kg and detomidine 0.015 mg/kg. Anaesthesia was induced with ketamine 2 mg/kg and diazepam 0.03 mg/kg, and maintained with an infusion of propofol at an initial rate of 0.16 mg/kg/min for the first thirty minutes, after a bolus of 0.3 mg/kg; and ketamine by infusion (20–40 μg/kg/min). Blood samples (<2 mL) were collected prior to, during and after the infusion, and on assuming standing position. Anaesthesia was uneventful; with the duration of infusion 31–89 min. Blood propofol concentrations during the infusion ranged between 1.52 and 7.65 μg/mL; pseudo‐steady state concentrations 3.64–6.78 μg/mL, and concentrations on assuming standing position 0.75–1.40 μg/mL. Propofol clearance and volume of distribution were 31.4 (SD 6.1) mL/min/kg and 220.7 (132.0) mL/kg, respectively. The propofol analyser allows titration of propofol to a given concentration; and may be useful for anaesthesia in animals where kinetics are unknown; in disease states; and where intercurrent therapies affect propofol disposition.     

A pilot study: sodium urate synovitis as an acute model of inflammatory response using objective and subjective criteria to evaluate arthritic pain in cats

Sodium urate (SU) synovitis was evaluated as a model for feline arthritic pain using a placebo‐ and positive‐controlled (meloxicam) randomized blinded controlled single crossover design. Monosodium urate crystals [20 mg (1 mL) rod‐shaped] were injected into alternate stifles of trained anesthetized cats (n = 3) with a 28 day washout. During the first trial phase, two cats received meloxicam (0.1 mg/kg, PO), a nonsteroidal anti‐inflammatory drug (NSAID), for three days before and on the day of SU injection; the third cat received placebo. Treatments and stifles were switched for the second trial. Total force, contact pressure and area of the fore and hind limbs were measured using a pressure mat one day and 0.5 h before, and 2, 4, 6, 8, 10, 24, and 30 h post‐SU injection. Skin temperature, joint circumference, analgesia, lameness, and visual analogue scale (VAS) pain scores, were measured at the same times. Comparisons were made for each time and for areas under the curve (AUC) using original and change from baseline; P < 0.05 was significant. Significant differences in force mat data and subjective data were found for the hind limb data (total force and total contact pressure at 6, 10, and 30 h; analgesia and VAS for pain at 4 h; lameness at 10, 24, and 30 h) and for AUC₀→_24h and AUC₀→_30h (total force, total contact pressure, and mean lameness score) and for differences from BL AUC₀→_10h (total contact area) and AUC₀→_24h (total contact area and mean lameness score) and AUC₀→_30h (total force, total contact area, and mean lameness). No cats required rescue analgesia. Injection of 1 mL of monosodium urate into the stifle of a cat causes moderate transitory pain and was suitable for assessing analgesic efficacy of an NSAID with a pressure mat and subjective criteria.     

Impact of rewilding,species introductions and climate change on the structure and function of the Yukon boreal forest ecosystem

Community and ecosystem changes are happening in the pristine boreal forest ecosystem of the Yukon for 2 reasons. First, climate change is affecting the abiotic environment (temperature, rainfall and growing season) and driving changes in plant productivity and predator–prey interactions. Second, simultaneously change is occurring because of mammal species reintroductions and rewilding. The key ecological question is the impact these faunal changes will have on trophic dynamics. Primary productivity in the boreal forest is increasing because of climatic warming, but plant species composition is unlikely to change significantly during the next 50–100 years. The 9–10‐year population cycle of snowshoe hares will persist but could be reduced in amplitude if winter weather increases predator hunting efficiency. Small rodents have increased in abundance because of increased vegetation growth. Arctic ground squirrels have disappeared from the forest because of increased predator hunting efficiency associated with shrub growth. Reintroductions have occurred for 2 reasons: human reintroductions of large ungulates and natural recolonization of mammals and birds extending their geographic ranges. The deliberate rewilding of wood bison (Bison bison) and elk (Cervus canadensis) has changed the trophic structure of this boreal ecosystem very little. The natural range expansion of mountain lions (Puma concolor), mule deer (Odocoileus hemionus) and American marten (Martes americana) should have few ecosystem effects. Understanding potential changes will require long‐term monitoring studies and experiments on a scale we rarely deem possible. Ecosystems affected by climate change, species reintroductions and human alteration of habitats cannot remain stable and changes will be critically dependent on food web interactions.     

甘蓝型油菜(Brassica napus)无花瓣突变体“ Ap-Tengbe ”花瓣性状的遗传规律

本项研究旨在探明甘蓝型油菜突变体Ａｐ－Ｔｅｎｇｂｅ无花瓣性状的遗传规律,‘Ａｐ－Ｔｅｎｇｂｅ’和德国栽培品种‘Ｆａｌｃｏｎ’之间通过正反交产生两个方向的Ｆ１,ＢＣ１－１（Ｆ１和‘Ａｐ－Ｔｅｎｇｅｂｅ’之间）,ＢＣ１－２（Ｆ１和‘Ｆａｌｃｏｎ’之间）以及Ｆ２各遗传群体,根据田间各遗传群体ＰＤｇｒ（花瓣度）的观察和统计,作者提出‘Ａｐ－Ｔｅｎｇｅ’突变体无花瓣性状的遗传由细胞质和两对核隐性基因共同控制     

A proposed framework for accelerating technology trajectories in agriculture: a case study in China

Precision agriculture (PA) technologies have great potential for promoting sustainable intensification of food production, ensuring targeted delivery of agricultural inputs, and hence food security and environmental protection. The benefits of PA technologies are applicable across a broad range of agronomic, environmental and rural socio-economic contexts globally. However, farmer and land-manager adoption in low to middle income countries has typically been slower than that observed in more affluent countries. China is currently engaged in the process of agricultural modernisation to ensure food security for its 1.4 billion population and has developed a portfolio of policies designed to improve food security, while simultaneously promoting environmental protection. Particular attention has been paid to the reduction of agricultural inputs such as fertilisers and pesticides. The widespread adoption of PA technologies across the Chinese agricultural landscape is central to the success of these policies. However, socio-economic and cultural barriers, farm scale, (in particular the prevalence of smaller family farms) and demographic changes in the rural population, (for example, the movement of younger people to the cities) represent barriers to PA adoption across China. A framework for ensuring an acceptable and accelerated PA technology trajectory is proposed which combines systematic understanding of farmer and end-user priorities and preferences for technology design throughout the technology development process, and subsequent end-user requirements for implementation (including demonstration of economic and agronomic benefits, and knowledge transfer). Future research will validate the framework against qualitative and quantitative socio-economic, cultural and agronomic indicators of successful, or otherwise, PA implementation. The results will provide the evidence upon which to develop further policies regarding how to secure sustainable food production and how best to implement PA in China, as well as practical recommendations for optimising end-user uptake.     

Effects of dobutamine on cardiac index and arterial blood pressure in isoflurane-anaesthetized horses under clinical conditions

Volatile agent-induced hypotension may contribute to anaesthetic-related morbidity and mortality in horses. Dobutamine is commonly used to support arterial blood pressure (ABP) but little is known about its cardiovascular effects under clinical conditions. The aim of this clinical study was to elucidate the relationship between cardiovascular function and dobutamine infusion in isoflurane-anaesthetized horses. Forty-four horses anaesthetized for a variety of surgical procedures were studied. Premedication with acepromazine, methadone and detomidine was followed by induction of anaesthesia with ketamine and midazolam. Anaesthesia was maintained with isoflurane vaporized in oxygen. Routine anaesthetic monitoring was applied and cardiac output was measured by lithium dilution. Dobutamine was infused to maintain mean ABP above 70 mmHg. The relationship between dobutamine infusion rate, heart rate (HR), ABP and cardiac index was investigated immediately prior to ( T ₀) and 15 min ( T ₁) after dobutamine infusion started, followed at 30 min intervals ( T ₂, etc.). Arterial blood pressure increased significantly after dobutamine infusion started, HR and cardiac index increased significantly only with dobutamine infusion in combination with surgical stimulus. Although isoflurane decreases blood pressure mainly by vasodilation, dobutamine is an effective treatment for hypotension under clinical conditions in isoflurane-anaesthetized horses. The effect of dobutamine is not directly proportional to dose and surgical stimulus probably contributes to the cardiovascular improvement.     

Bacterial culture of septic synovial structures of horses: Does a positive bacterial culture influence prognosis?

Reasons for performing study: The influence of synovial fluid culture on short‐ and long‐term prognosis of cases with septic synovitis requires study. Hypotheses: Horses with a positive bacterial culture from septic synovial fluid are less likely to survive or return to successful athletic function than those with a negative bacterial culture from septic synovial fluid. Methods: Records of mature horses presented to 2 equine referral hospitals for investigation of suspected septic synovitis were examined. Horses (n = 206) were included in the study if synovial fluid was submitted for full laboratory examination, including bacterial culture. A diagnosis of septic synovitis was based on a nucleated cell count >30 × 10⁹ cells/l or >90% neutrophils and other clinical, cytological and bacteriological parameters. Long‐term follow‐up was obtained by telephone questionnaire. Univariate analysis, using the Fisher's exact test, was used for all outcomes. Results: Fourteen (20.9%) of 67 horses with a positive bacterial culture from synovial fluid were subjected to euthanasia because of persistent synovial sepsis compared to 2 (1.44%) of 139 with negative bacterial cultures (P<0.001). Overall survival and successful long‐term return to function in horses with a positive bacterial culture was 50% (24/48 horses) compared to 70.5% (74/105) in culture negative horses (P = 0.01). In horses that survived to be discharged, successful long‐term return to function was not significantly different between culture positive and culture negative groups. Growth of Staphylococcus aureus from synovial fluid did not affect short‐term survival to discharge from the hospital compared to other positive bacterial culture; however, successful long‐term return to function was only 30.4% (4/13) in horses from which S. aureus was cultured compared to 73.9% (17/23) of horses in which other bacteria were cultured (P = 0.015). Conclusions and potential clinical relevance: Horses with a positive bacterial culture from a septic synovitis have a poorer prognosis for survival to discharge from hospital and overall long‐term return to function than horses that yielded no bacterial growth. When S. aureus was cultured, the long‐term prognosis was poorer.