Response of equine airway smooth muscle to acetylcholine and electrical stimulation in vitro

Smooth muscle strips from the midcervical portion of the trachea and bronchial smooth muscle strips from third-generation airways of horses were placed in tissue baths, and isometric contractile force was measured. Active force was measured in response to electrical stimulation and exogenous acetylcholine. Square-wave electrical stimuli were applied at various voltages (10, 12, 15, 18, 20, 25 V), frequencies (3, 5, 10, 15, 20, 25, 30 Hz), and pulse durations (0.2, 0.5, 1.0, 1.5, 2.0 ms). Isometric contractile force increased as voltage, frequency, and pulse duration increased. Maximal contractile response to electrical stimulation was obtained at 18 V, 25 Hz, and 0.5 ms. Atropine (10(-6)M) or tetrodotoxin (3 x 10(-6)M) blocked the contraction, indicating that the contractile response was attributable to the release of neurotransmitter from cholinergic nerves. Cumulative concentration-response curves to acetylcholine (10(-9)M through 10(-4)M) were determined. Isometric contractile force increased as acetylcholine concentration increased. There was a significant (P less than 0.05) difference in the 50% effective dose for acetylcholine in tracheal smooth muscle and bronchial smooth muscle. The mean (+/- SD) contractile response to maximal electrical stimulus was 89% (+/- 7.4%) of that in response to 10(-4)M acetylcholine in tracheal smooth muscle and was 68% (+/- 10.4%) of the response to 10(-4)M acetylcholine in bronchial smooth muscle.     

Multifocal necrotising steatites associated with pancreatic carcinoma in three dogs

Multiple subcutaneous swellings and discharging sinuses were a result of steatitis in three dogs. The steatitis in each case was thought to be associated with a pancreatic carcinoma. The association with pancreatic neoplasia had been suspected in life in only one dog but was confirmed at necropsy in each case. Circulating levels of pancreatic enzymes were increased in the one dog in which they were measured.     

Transient infections of goats with a novel spotted fever group rickettsia from Zimbabwe

A novel spotted fever group rickettsia has recently been isolated from Amblyomma hebraeum ticks in Zimbabwe. In a survey of 172 goat sera collected throughout Zimbabwe the highest prevalence of antibodies reactive with this rickettsia was in the south of the country, the area where A hebraeum is most commonly found. Nine goats were infected using male and female A hebraeum taken from a tick line shown to be infected with the novel rickettsia. By week 3 after infection, seroconversion occurred in all nine goats but no clinical signs of disease could be detected. A leucocytosis due to a mature neutrophilia one to two weeks after infection was the only abnormality. Rickettsaemia was detected only on day 3 after exposure to infected ticks. Immunosuppression failed to induce recrudescence of the rickettsaemia.     

Surgical repair of femoral neck fractures in two dogs and a calf

The surgical techniques employed in the repair of femoral neck fractures in two dogs and a Charolais calf are described. All the fractures were extracapsular; one of the dogs also had a fractured femoral diaphysis. For both dogs, exposure of the femoral neck was made from a dorsal approach after removal of the greater trochanter, while for the calf, a gluteal transection technique was used. All the fractures were successfully fixed using cortical screws, and in the case of the femoral diaphysis, a vitallium plate was used. All the animals were walking with minimal lameness eight weeks after surgery.     

Nanodisks protect amphotericin B from ultraviolet light and oxidation‐induced damage

BACKGROUND: Macrolide polyene antibiotics possess potent broad‐spectrum antifungal properties. Use of these agents in the field or in controlled environments is impeded by their poor water solubility and susceptibility to oxidation‐ and/or light‐induced degradation. While typically used for human disease therapy, there is potential to expand the utility of polyene macrolide antibiotics, such as amphotericin B, for control of fungal disease infestation in agricultural settings. Thus, the susceptibility of this antibiotic to exposure‐induced activity loss was evaluated. RESULTS: Incubation of the prototype polyene amphotericin B (AMB) with phospholipid vesicles and apolipoprotein A‐I results in the formation of nanoscale complexes, termed nanodisks (NDs), capable of solubilizing significant quantities of AMB. To evaluate whether AMB incorporation into NDs conferred protection against light‐ or oxidation‐induced damage, yeast growth inhibition assays were conducted. Compared with AMB solubilized in detergent micelles, AMB incorporated into NDs was protected from damage caused by exposure to UV light as well as by KMnO₄‐induced oxidation. Furthermore, AMB‐NDs inhibited growth of the turfgrass fungus Marasmius oreades Fr. CONCLUSION: Results suggest that this water‐soluble formulation of a natural, biodegradable, antifungal agent represents a potential cost‐effective, non‐toxic and environmentally friendly substitute for chemical agents currently employed to control a range of fungal infestations. Copyright © 2009 Society of Chemical Industry     

Design and Performance of a Simulated Feedstock for Composting Experiments

This paper reviews the composition and performance of simulated feedstock mixtures previously employed in composting research, and presents a new simulated feedstock. The new feedstock was prepared using readily available dry ingredients — ostrich feed pellets, office paper, finished compost and woodchips — representing the substrate, amendment, seed, and bulking agent components of a composting mixture respectively. The design criteria chosen were a) a substrate plus amendment C:N ratio of 30:1, b) an energy ratio of > 800 cal/g-H₂O, c) a water ratio of < 8 g-H₂O/g-BVS, d) a wet bulk density of < 600 kg/m³ and e) a moisture content of 60% (w/w). Resultant final proportions of the substrate:amendment:seed:bulking-agent:added-water mix were 0.071:0.098:0.009:0.267:0.555 (w/w). When composted in a controlled temperature difference (CTD), forced-aeration reactor operated with condensate return, the mixture was shown to self-heat rapidly and remain at realistic temperatures for extended periods. Thermophilic temperatures were reached within 22-33 h of start-up, following lag periods of 13-22 h, and maintained for up to 34 d. Final compost characteristics were consistent with a normal composting process. It is suggested that future variations in the simulated feedstock composition could be made, and proposed that use of this type of feedstock would facilitate future experimental work associated with composting kinetics and temperature profile modeling.