Lethal Effects of Pulsed High-Voltage Discharge on Marine Plankton and Escherichia coli

Ballast seawater is considered globally as a major vector for invasions of non-indigenous organisms. Several technologies have been tested for their ability to remove organisms from ballast water. In the present study, we constructed a novel pulsed high-voltage discharge (PHVD) system that could operate in either high current mode with several hundred amperes or shockwave generating mode with relatively lower current in seawater. In laboratory-scale experiments, the PHVD system with shockwave-generating mode was found to be more effective in killing zooplankton (1.9- to 4.0-fold) and phytoplankton (3.3-fold) than high current mode at discharge with 300–500 pulses at 7.1 kV. Further experiments were carried out at different voltages and pulse-numbers to examine effects of the shockwave-generating PHVD system on viabilities of one zooplankton larva, two phytoplankton species, and an indicator bacterium suspended in seawater in a static chamber. For zooplankton, live cells were not detected at discharge with 400 pulses at 13 kV. For phytoplankton, the initial live cells of a dinoflagellate was decreased by 77?±?0.5%, and the initial chl a concentration of a diatom was decreased by 76?±?6% at discharge with 700 pulses at 13 kV. For an indicator bacterium Escherichia coli, live cells were not detected at discharges with 200 or 700 pulses at 13 kV. Measurements of ATP content of organisms showed congruent results with those obtained by the above methods, suggesting it may be a rapid method for evaluating treatment efficiency. Though further scale-up studies are necessary, these results suggest that the PHVD system have a high potential for applying to ballast seawater treatment.     

Microbial dynamics and natural remediation patterns of Fusarium‐infested watermelon soil under 3‐yr of continuous fallow condition

Long‐term monoculture of watermelon results in inhibited growth and decreased crop yields, possibly because of imbalance in microbial ecology caused by accumulation of the pathogen in soil. This results in serious problems in the economics of watermelon production. We investigated the build‐up of Fusarium in soil under watermelon cultivation and changes over 3 yr of fallow in a microcosm. We focused on changes in the microbial community of Fusarium‐infected soil, including the diversity of the microfloral species composition, and species abundance. Long‐term monoculture of watermelon leads to changes in microbial diversity and community structure. The microbes most readily cultured from infested soil were suppressed by watermelon wilt pathogen Fusarium oxysporum f. sp. niveum (FON). Of 52 isolated and identified culturable microbes, 83.3% of bacteria, 85.7% of actinomycetes, 31.6% of fungi and 20.0% of Fusarium sp. were inhibited by FON on bioassay plates. Prior to fallowing, infested soil was a transformed ‘fungus‐type’ soil. After 3 yr of fallow, the infested soil had remediated naturally, and soil microbial diversity recovered considerably. Abundance of dominant bacterial populations was increased by 118–177%, actinomycetes, fungi and FON were decreased by 23–32, 33–37 and 50%, respectively. The ratio of bacteria: actnomycetes: fungus: Fusarium sp. in infested soil changed from 24 000:100:4:1 prior to fallow to 57 000:100:3.5:1 after fallowing, nearer to the 560 000:400:8:1 ratio of healthy soil not used for watermelon cultivation. This suggests the ‘fungus‐type’ soil was converting to ‘bacteria‐type’ soil and that disrupted microbial communities in infested soil were restored during fallow.     

Excessive application of nitrogen and phosphorus fertilizers induces soil acidification and phosphorus enrichment during vegetable production in Yangtze River Delta,China

Intensive vegetable cultivation has developed very rapidly in China, and investigation of current soil nutrient problems in vegetable fields and their potential environmental risk is important for local soil nutrient management strategies. Three hundred and sixty‐six soil samples were collected from greenhouse vegetable fields, open vegetable fields and rice/wheat rotation fields in southern Jiangsu Province, the most intensive vegetable‐producing areas in Yangtze River Delta, China, for the analysis of their soil fertility status. Soil acidification and P enrichment were the main problems identified in this area of vegetable production, with about 20 and 17% of the open and greenhouse vegetable field soils, respectively, being extremely acid with soil pH values below 5.0. In contrast, no soils under rice/wheat rotation fields were as acidic. Percentages of sites with Olsen‐P concentrations < 90 mg/kg were 61, 85 and 0% for soils growing greenhouse vegetable, field vegetable and rice/wheat, respectively. The nitrogen (N) surplus for vegetable fields exceeded 170 kg/ha/crop, and the phosphorus (P) surplus exceeded 40 kg/ha/crop. Thus, current vegetable production leads to potential environmental risks of N and P pollution of nearby aquatic bodies. Insufficient supplementation with potassium fertilizers was found in some vegetable fields. Several ameliorative measures are proposed.     

Role of oxytocin and/or PGF2 alpha on breeding efficiency in buffaloes

A study was conducted on 40 buffalo-cows, assigned randomly, immediately after calving into three groups: group I (n = 10) injected with saline and taken as control; group II (n = 15) received 25 mg PGF2 alpha/animal (Lutalyse); group III (n = 15) received 25 mg PGF2 alpha + 25 i.u. oxytocin/animal (Syntocinon), single i.m. dose. Oxytocin and/or PGF2 alpha significantly (P less than 0.01) shortened the interval from calving to first service (38.33 and 31.53 days for groups II and III respectively, versus 91.60 days for controls). The treatment reduced the service period (38.29 and 35.87 days for groups II and III respectively, versus 45.40 days for controls). Concomitantly a significant (P less than 0.01) decrease in the open-days post partum was achieved (76.62 and 67.40 days for groups II and III respectively, versus 137.00 days for controls). In addition, the treated buffaloes needed significantly (P less than 0.01) fewer services per conception (1.67 and 1.20 S/C for groups II and III respectively) than the untreated ones (2.70 S/C), besides a substantial improvement (P less than 0.01) in their conception rate either at 60 or 85 days post partum. Significantly improved (P less than 0.05) results were obtained in the oxytocin and PGF2 alpha treated animals, than in those receiving PGF2 alpha alone for all the previous parameters, except for the service period. Buffaloes therefore seemed to respond better to such treatment than dairy cows.     

Evaluation of Surgical Scrub Methods for Large Animal Surgeons

Objective— The objective of this study was to determine the effectiveness of a 5–minute surgical scrub using either a one-brush or a two-brush technique in clean and dirty surgical procedures, and to compare the efficacy of povidone iodine with chlorhexidine as surgical scrub solutions. Study Design— Prospective clinical trial. Methods— Nine veterinarians scrubbed their hands on eight separate occasions using either povidone iodine or chlorhexidine gluconate. A 5-minute scrub and either a one-brush or two-brush technique used in both clean and dirty operations were evaluated by taking glove juice samples before scrubbing, immediately after scrubbing, and 30, 60, 90, and 120 minutes after scrubbing. Glove juice samples were cultured and the colonies were counted. Percent reductions of bacterial forming units were calculated for all eight scrub procedures. Results— All scrub procedures provided an adequate percent reduction in colony forming units (CFU) during the 2–hour sampling period. The number of CFU immediately after scrubbing were significantly lower than prescrub. At 120 minutes, there were significantly fewer CFUs than presecrub, but there were more than immediately after scrubbing. No significant difference in reduction in CFUs were detected between one-brush and two-brush techniques. Both chlorhexidine and povidone iodine scrub solutions adequately reduced bacterial colony counts for 120 minutes after scrubbing regardless of the amount of contamination before skin preparation. Conclusions— Bacterial counts after a hand scrub procedure using a one-brush technique were not significantly different than after a procedure that used a two-brush technique. Povidone iodine and chlorhexidine are equally effectively in decreasing bacterial numbers on the skin, given a variety of contamination levels present before the scrub procedure. Clinical Relevance— Surgeons may use either chlorhexidine or povidone iodine for antiseptic preparation of their hands before surgery. A two-brush technique is not necessary.     

The Canadian Cooperative Wildlife Health Centre and surveillance of wild animal diseases in Canada.

The Canadian Cooperative Wildlife Health Centre (CCWHC) was established in 1992 as an organization among Canada's 4 veterinary colleges, with a mandate to apply veterinary medicine to wildlife management and conservation in Canada. A major function of the CCWHC is nation-wide surveillance of wild animal diseases. Disease surveillance is conceived as consisting of 4 different activities: detection, diagnosis, information management, and use of information. In the CCWHC surveillance program, detection of disease is carried out by a wide range of professional and avocational field personnel, and much effort is expended to stimulate and support this activity. Diagnosis is done by personnel of provincial and federal veterinary laboratories and the CCWHC. Information management is achieved through a national database of wildlife disease incidents developed and maintained by the CCWHC. Use of information is enabled through established channels for distribution of information derived from the surveillance program to persons responsible for wildlife programs and policies, and to the public. There has been a high demand for the services of the CCWHC since its establishment. The CCWHC responds to approximately 2000 requests for information annually, distributes its newsletter to over 1700 recipients, examines approximately 1200 wild animal submissions each year, and has accumulated records of over 5000 disease incidents in its database. Technical information from the CCWHC has benefited federal, provincial/territorial, and nongovernment wildlife agencies; endangered species recovery programs; federal and provincial veterinary services; and federal and provincial public health programs.     

Propionate loading test for liver function in spontaneously ketotic dairy cows

Propionate utilisation by the liver in spontaneously ketotic dairy cows was investigated by determining blood glucose levels after an intravenous sodium propionate load (2.5 mmol kg-1). In addition, blood ketone body concentrations were measured after propionate loading. Cows were divided into three groups (control, mildly ketotic and severely ketotic) by their blood acetoacetate concentrations. Plasma glucose concentrations increased significantly after sodium propionate injection in all three groups (P less than 0.05). The maximum glucose concentration occurred earlier in the control group than in the ketotic groups. Changes in glucose concentrations following propionate loading of control and ketotic cows differed significantly at 20 minutes and beyond. Differences in the change in glucose concentration between mildly ketotic and severely ketotic cows were not significant. Acetoacetate concentration was significantly decreased at five minutes and beyond after the injection in ketotic cows, whereas beta-hydroxybutyrate concentration decreased more slowly. A decrease in beta-hydroxybutyrate concentration was significant at 40 minutes and beyond in the severely ketotic group and at 10 minutes and beyond in the mildly ketotic group after loading.