Effects of muscarinic receptor antagonists on acetylcholine-induced contractions of jejunal smooth muscle in horses

This study investigated the effects of a muscarinic type 1 (M(1)), 2 (M(2)), and 3 (M(3)) antagonists (4-DAMP, pirenzepine, and methoctramine, respectively) on acetylcholine (Ach)-induced contractions of longitudinal jejunal muscle strips of horses. Strips were irrigated with Krebs-Henseleit solution gassed with 95% O(2) and 5% CO(2), and the developed tension in response to Ach was recorded before and after incubation with increasing concentrations of 4-DAMP (10(-8)-10(-6) M), pirenzepine (10(-6)-10(-4) M), and methoctramine (10(-5)-10(-3) M). When competitive antagonism was characterized, the affinity constant (pA(2)) was calculated by Schild plots. A parallel rightward shift in the concentration-response curves was observed after 4-DAMP and pirenzepine. Methoctramine presented a dual effect on the concentration-response curves: lower concentrations induced a parallel rightward shift without altering the maximum intensity of contraction (E(max)), while the highest concentration increased slope of the concentration-response curve and increased E(max). The pA(2) for 4-DAMP and pirenzepine was 9.18 and 7.13, respectively. Acetylcholine-induced contractions of longitudinal jejunal smooth muscle are mediated mainly via M(3) receptors. The complex role of M(2) receptors in jejunal smooth muscle contractions was evident because methoctramine potentiated the contractile response to higher doses of Ach.     

Bubblegrams reveal the inner body of bacteriophage φKZ

Dense packing of macromolecules in cellular compartments and higher-order assemblies makes it difficult to pick out even quite large components in electron micrographs, despite nominally high resolution. Immunogold labeling and histochemical procedures offer ways to map certain components but are limited in their applicability. Here, we present a differential mapping procedure, based on the physical principle of protein's greater sensitivity to radiation damage compared with that of nucleic acid.     

Responses of trembling aspen and hazelnut to vapor pressure deficit in a boreal deciduous forest

The branch bag method was used to monitor photosynthesis and transpiration of trembling aspen (Populus tremuloides Michx.) and hazelnut (Corylus cornuta Marsh.) over a 42-day midsummer period in 1996, as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). During the same period, daytime measurements of stomatal conductance (g(s)) and leaf water potential (Psi(leaf)) were made on these species, and sap flow was monitored in aspen stems by the heat pulse method. Weather conditions during the study period were similar to the long-term average. Despite moist soils, both species showed an inverse relationship between daytime g(s) and vapor pressure deficit (D) when D was > 0.5 kPa. Daytime Psi(leaf) was below -2 MPa in aspen and near -1.5 MPa in hazelnut, except on rainy days. These results are consistent with the hypothesis that stomatal responses are constrained by hydraulic resistance from root to leaf, and by the need to maintain Psi(leaf) above a minimum threshold value. Reductions in g(s) on sunny afternoons with elevated ambient D (maximum 2.3 kPa) were associated with a significant decrease in photosynthetic rates. However, day-to-day variation in mean carbon assimilation rate was small in both species, and appeared to be governed more by solar radiation than D. These results may be generally applicable to healthy aspen stands under normal midsummer conditions in the southern boreal forest. However, strong reductions in carbon uptake may be expected at the more extreme values of D (> 4 kPa) that occur during periods of regional drought, even if soil water is not locally limiting.     

Lantana poisoning of cattle and sheep in New Zealand

The investigation of a field case of Lantana camara poisoning in cattle is reported. Toxicity was confirmed by the experimental dosing of two sheep with dried leaf powder at 6 and 12 mg/kg body weight. Marked cholestatic hepatophy and renal tubular disease resulted. This is the first reported case of toxicity due to grazing a Lantana camara variety grown in New Zealand.     

Nutrition professionals' perception of the 'healthiness' of individual foods

OBJECTIVES: This paper describes the development of an online questionnaire for testing nutrition professionals' perceptions of the 'healthiness' of individual foods and the results of administering that questionnaire. The questionnaire was designed to produce a standard ranking of foods that can be used as a tool for testing nutrient profile models. DESIGN: The questionnaire asked respondents to categorise 40 foods (from a master list of 120) in one of six positions, ranging from less to more healthy. The 120 foods were selected to be representative of the British diet. The questionnaire was sent via email to nutrition professionals from the British Dietetic Association and the (British) Nutrition Society. RESULTS: Eight hundred and fifty responses were received. These responses were used to rank the 120 foods by the average score which they received from the nutrition professionals. A regression analysis was also carried out to examine the relationship between the scores awarded by the nutrition professionals and various features of the foods: their nutritional content, their average serving size, their frequency of consumption, whether they were drinks or foods, etc. Nearly 50% of the variance in the average scores was explained by the nutritional content of the foods. When other variables were included in the analysis the percentage of variance that was explained increased to 64%. CONCLUSIONS: The average scores of the foods produce a standard ranking, which can be used as a tool for validating and comparing nutrient profile models. The regression analysis provides some information about how nutrition professionals rank the 'healthiness' of individual foods.     

The behaviour of male lambs transported by sea from New Zealand to Saudi Arabia

The behaviour of two pens of mixed British breed male sheep transported by ship from New Zealand to Saudi Arabia was studied. One of the groups was carried above decks (n = 128) and one below decks (n = 116). Observations were conducted four to five times daily throughout the 24-day voyage. Over the whole voyage the most common activities were standing, lying and feeding. Overall, the animals adapted reasonably well to the shipboard environment, with most gaining weight. The mortality rate in the study pens averaged 2.5%, which was similar to that of the total shipment and average for this type of voyage. The behavioural measures appeared to provide sensitive indices of changes in the welfare of the sheep. An increase in lying activity, panting and drinking and a decrease in feeding during the latter part of the voyage were indicative of increasing heat stress. Plunging at the feed and water troughs led to loss of footing and increased the likelihood of smothering. This activity occurred after periods without feed or without water. Plunging also occurred when sheep moved towards the ventilators. Other factors associated with reduced well-being were the high stocking density which, combined with a wet faecal pad, limited movement towards feed or water and increased the likelihood of smothering.     

Determining sediment properties around a marine cage farm using acoustic ground discrimination: RoxAnnTM

Sediment traps collected significant quantities of waste solids beneath marine fish cages at a fish farm site in Greece. Diver observation and the absence of dissolved hydrogen sulphide in the water overlying sediments revealed low benthic impacts despite the very low current speeds measured. An acoustic bottom discrimination system, ground-truthed by conventional remote photography, further confirmed the apparently low benthic impact at this site. These results may be explained partly by the large number of fish present around the cages feeding on farm wastes.