A Low-fidelity Simulator for the Development of Vascular Ligation Skills.

Training simulators can facilitate the acquisition and development of basic surgical skills, and they constitute a safe and humane method that does not harm animals in the process. The objective of this work was to create and evaluate a low-cost simulator to help undergraduate students of veterinary medicine acquire and practise vascular ligation skills. A training model was made by using easily accessible and inexpensive materials. Fifteen students, without prior surgical experience, each performed the orchiectomy technique on the simulator seven times. The emphasis was on performing vascular ligatures in both testicles of the simulator (n = 14), in two different scenarios: firstly, with the contents of the blood vessels not under pressure; and secondly, with the syringe plunger depressed by 1 ml to pressurise the blood vessels. The outcomes of the procedure in the simulator were based on three qualitative criteria: Correct (no 'bleeding'), Sufficient (light 'bleeding') and Incorrect (heavy 'bleeding'). After the seventh attempt, all participants were able to perform vascular ligatures with at least a score of Sufficient in both scenarios. By the 10th ligature attempt, they were all able to perform the procedure with a score of Correct (p < 0.05). There was a trend toward a decrease in the time taken to carry out the procedure as learning progress was made during training, with this being significant from the 12th attempt (p < 0.05). The use of this low-cost simulator represents a useful didactic tool, which supports the acquisition and practise of manual skills by using methods that do not involve the use of animals. In addition, this training simulator could be useful in distance learning, in view of the ready accessibility of the materials required for its construction.

Kinetic Properties of Microbial Exoenzymes Vary With Soil Depth but Have Similar Temperature Sensitivities Through the Soil Profile.

Current knowledge of the mechanisms driving soil organic matter (SOM) turnover and responses to warming is mainly limited to surface soils, although over 50% of global soil carbon is contained in subsoils. Deep soils have different physicochemical properties, nutrient inputs, and microbiomes, which may harbor distinct functional traits and lead to different SOM dynamics and temperature responses. We hypothesized that kinetic and thermal properties of soil exoenzymes, which mediate SOM depolymerization, vary with soil depth, reflecting microbial adaptation to distinct substrate and temperature regimes. We determined the Michaelis-Menten (MM) kinetics of three ubiquitous enzymes involved in carbon (C), nitrogen (N) and phosphorus (P) acquisition at six soil depths down to 90 cm at a temperate forest, and their temperature sensitivity based on Arrhenius/Q 10 and Macromolecular Rate Theory (MMRT) models over six temperatures between 4-50°C. Maximal enzyme velocity (V max) decreased strongly with depth for all enzymes, both on a dry soil mass and a microbial biomass C basis, whereas their affinities increased, indicating adaptation to lower substrate availability. Surprisingly, microbial biomass-specific catalytic efficiencies also decreased with depth, except for the P-acquiring enzyme, indicating distinct nutrient demands at depth relative to microbial abundance. These results suggested that deep soil microbiomes encode enzymes with intrinsically lower turnover and/or produce less enzymes per cell, reflecting distinct life strategies. The relative kinetics between different enzymes also varied with depth, suggesting an increase in relative P demand with depth, or that phosphatases may be involved in C acquisition. V max and catalytic efficiency increased consistently with temperature for all enzymes, leading to overall higher SOM-decomposition potential, but enzyme temperature sensitivity was similar at all depths and between enzymes, based on both Arrhenius/Q 10 and MMRT models. In a few cases, however, temperature affected differently the kinetic properties of distinct enzymes at discrete depths, suggesting that it may alter the relative depolymerization of different compounds. We show that soil exoenzyme kinetics may reflect intrinsic traits of microbiomes adapted to distinct soil depths, although their temperature sensitivity is remarkably uniform. These results improve our understanding of critical mechanisms underlying SOM dynamics and responses to changing temperatures through the soil profile.

Commercially available garden products as important sources of antibiotic resistance genes-a survey.

The dissemination of antibiotic resistance genes (ARGs) in the environment contributes to the global rise in antibiotic resistant infections. Therefore, it is of importance to further research the exposure pathways of these emerging contaminants to humans. This study explores commercially available garden products containing animal manure as a source of ARGs in a survey of 34 garden products, 3 recently landscaped soils, and 5 native soils. DNA was extracted from these soils and quantified for 5 ARGs, intI1, and 16S rRNA. This study found that both absolute and relative gene abundances in garden products ranged from approximately two to greater than four orders of magnitude higher than those observed in native soils. Garden products with Organic Materials Review Institute (OMRI) certification did not have significantly different ARG abundances. Results here indicate that garden products are important sources of ARGs to gardens, lawns, and parks.