Voltage-dependent ion channels have been found in the plasma membrane of the yeast Saccharomyces cerevisiae. Ion channel activities were recorded from spheroplasts or patches of plasma membrane with the patch-clamp technique. The most prominent activities came from a set of potassium channels with the properties of activation by positive but not negative voltages, high selectivity for potassium over sodium ion, unit conductance of 20 picosiemens, inhibition by tetraethylammonium or barium ions, and bursting kinetics. 相似文献
This study’s aim is to inventory antibiotics used in cattle in North-East Benin and assess risk practices that could be the cause of both food chain contamination by antibiotic residues and selection of antibiotic-resistant bacteria in animals and humans. A survey was conducted among 98 cattle breeders in the districts of Banikoara, Kandi, Bembereke, and Kalale in North Benin. Semi-structured interviews were conducted, covering breeder status, breeding system, and antibiotic use. Multiple correspondence analysis and hierarchical classification analysis were conducted to establish a breeder typology. Breeders mainly belonged to the Fulani ethnic group (71.4?±?8.9%) and almost all of them received “no formal education” (96.9?±?3.4%). Cattle herds were mainly composed of a single breed, the Borgou (76.4?±?8.1%) or the Fulani Zebu (16.0?±?7.0%). Some herds were mixed. Antibiotics groups used in cattle breeding were tetracyclines, beta-lactams, sulfonamides, aminoglycosides, and macrolides, used by respectively 100%, 69.4?±?9.1%, 56.1?±?9.8%, 44.9?±?9.8%, and 34.7?±?9.4% of breeders. These drugs were purchased in local markets (59.0?±?15.4%) and veterinary pharmacy (41.0?±?15.4%). They were mainly used against respiratory diseases, lameness, mastitis, omphalitis and neonatal enteritis, and skin diseases. Only 49.0?±?9.9% of breeders seek veterinary services to treat animals and 92.9?±?5.1% of them did not respect antibiotic withdrawal times. These practices suggest that both contamination of bovine meat with antibiotic residues and selection of resistant bacteria are to be expected, resulting in adverse health effects on consumers.
Fertility of primiparous lactating does in the early postpartum (pp) period is very low mainly due to pronounced deficient energy intake, influencing oocyte and embryo developmental competence. The hypothesis used in this work was that high‐lignin fibre diet supplied during the rearing period could increase feed intake and, consequently, improve the reproductive physiology and metabolic status of primiparous does in the early pp period. Diets with high‐lignin [HL: 15.8% dry matter (DM)] or standard‐lignin content (SL: 4.9% DM) were supplied until parturition time. No diet effects in serum oestradiol, progesterone concentrations and follicle categories were found in the histological study. Metaphase II rate of in vitro‐matured oocytes was significantly higher in the SL vs the HL group (p<0.001). Cytoplasmically degenerated oocytes (in terms of abnormal distribution of cortical granules) and follicular atresia rate were significantly lower in the SL group than in the HL group (p<0.05 and p<0.005 respectively). In addition, HL‐fed does showed lower number of viable embryos and higher rate of retarded in vivo‐recovered embryos compared with the SL group (p<0.05). Neither in vitro embryo development of viable embryos nor conception rate was significantly different between groups. Feed intake increased during the first pregnancy in the HL group (p<0.05), but not during early lactation. Serum protein, non‐esterified fatty acid and leptin concentrations, as well as estimated body composition were similar in does fed with both diets. In conclusion, the enhancement of reproductive management by using highly lignified products in rearing diets does not seem to report physiological reproductive benefits affecting oocyte maturation rate and embryo viability in primiparous lactating does. 相似文献
This study investigated the effect of inhaled fluticasone on lower airway inflammation and bronchial responsiveness (BR) to inhaled carbachol in cats with very mild, chronic bronchitis (n = 5) that were compared with healthy cats serving as controls (n = 6). Chest radiographs, BR tests performed non-invasively by barometric whole body plethysmography (BWBP) and bronchoalveolar lavage (BAL) were performed before and after treatment. BR was quantified by calculating the concentration of carbachol inducing bronchoconstriction (C-Penh300%), defined as a 300% increase of baseline Penh, an index of bronchoconstriction obtained by BWBP. BAL fluid was analyzed cytologically and the oxidant marker 8-iso-PGF2alpha was determined. At test 1, healthy cats and cats with bronchitis were untreated, whereas for test 2 inhalant fluticasone (250 microg once daily) was administrated for 2 consecutive weeks to cats with bronchitis. Control cats remained untreated. Inhaled fluticasone induced a significant increase in C-Penh300% and a significant decrease of BAL fluid total cells, macrophages, neutrophils and 8-iso-PGF2alpha in cats with bronchitis, whilst untreated control cats did not show significant changes over time. This study shows that a 2-week fluticasone treatment significantly reduced lower airway inflammation in very mild bronchitis. BR could be successfully monitored in cats using BWPB and decreased significantly in response to inhaled fluticasone. 8-Iso-PGF2alpha in BAL fluid was responsive to treatment and appeared as a sensitive biomarker of lower airway inflammation in cats. 相似文献
Parameters known to influence mercury (Hg) release from soils include substrate and air Hg concentration, light, atmospheric oxidants, temperature, and soil moisture. However, for low Hg-containing soils, the influence of these parameters has been shown to vary across space and time. Here, we expand upon previous work by investigating whether soil–water evaporative loss, which integrates the influence of multiple parameters, could be applied for predicting Hg flux from soil with low Hg concentrations when bare and planted. To investigate our hypothesis, Hg flux was measured from three soil types (<100 ng Hg g?1). When these soils were saturated, flux was suppressed. Soil moisture evaporative stage was used to partition the parameters most important for controlling Hg flux as the soils dried. Classification and regression tree (CART) analyses showed that soil moisture was the most important parameter predicting Hg flux. Results also showed an important predictor for Hg flux was whether actual evaporation (Ea) was equal to potential evaporation (Ep) or Ea < Ep. Depending on evaporative stage, the parameters with the next highest correlation to Hg flux were light, temperature, and soil moisture evaporation rate. The presence of vegetation also influenced flux with lower Hg flux when the plants were transpiring. Results indicate for those developing models that estimate Hg flux from low Hg-containing soils, soil moisture and evaporative stage are useful tools for predicting flux.
The effects of atmospheric ammonia (NH3) on the nasal and tracheal mucosa of pigs were investigated by morphometric and functional methods. Pigs were exposed to four concentrations of NH3 [5 (control), 25, 50 and 100 ppm] for 6 days in a specially designed air-pollutant exposure chamber. Samples were taken from the turbinates and the trachea, and the respiratory mucosa was examined by light and scanning electron microscopy. Dose-response curves to carbachol and isoproterenol were constructed using isolated strips of tracheal smooth muscle, with or without epithelium. In pigs exposed to ammonia, considerable mucosal injuries were observed in the turbinates but not in the trachea. The number of neutrophils in the epithelial layer and in the lamina propria, and epithelial hyperplasia were closely and significantly correlated with the concentrations of ammonia (r=0.894, p<0.001; r=0.727, p<0.001; and r=0.818, p<0.001, respectively). Except for the lamina propria, all these changes were significant (p<0.05) at ammonia concentrations as low as 25 ppm. The percentage of the surface of the turbinate mucosa that was ciliated tended to decrease with increasing ammonia concentration (r=0.439, p<0.082). Ammonia induced smooth-muscle hyperresponsiveness to carbachol with a close linear correlation between individual values of the carbachol-induced maximal effect and the NH3 concentrations (r=0.526, p<0.003). While mechanical destruction of the epithelium induced an increase in Emax in the control group, no difference was observed between the intact and denuded strips from animals exposed to ammonia. The response to isoproterenol was not influenced by ammonia. It was concluded that quantitative histological analysis of the inflammatory infiltration and epithelial hyperplasia in the turbinates is a useful tool for quantifying the effects of atmospheric pollutants in pigs; a 6-day exposure to ammonia induces nasal irritation and functional disturbances of the tracheal smooth-muscle contractions at concentrations as low as 25 ppm.Abbreviations
Emax
maximal effect
- IM
intramuscularly
- IV
intravenously
- NAL
nasal lavage
- pD2
negative logarithm of the molar concentration of agonist which induces an increase in tension equivalent to 50% of the maximal effect Emax expressed as grams force per mg of dry weight
-
r
correlation coefficient 相似文献
SUMMARY Merino sheep, which were hand jetted with ivermectin jetting fluid, and untreated sheep were challenged with larval implants of Lucilia cuprina, Lucilia sericata, Calliphora noclva and Chrysomya ruflfacles at intervals of about 2 weeks from 6 to 16 weeks after treatment. Both Lucilia species produced strike rates of about 90% in untreated sheep; the respective rates were lower for Chr rufifacies (55%) and C nociva (60%). Strike rates for the treated group were about 17, 11, and 9% for L cuprina, L sericata, and Chr rufifacies, respectively. Only 1 implant site in the treated group was struck by C nociva. Treated sheep had significantly (P < 0.01) longer time to first strike than did untreated ones for each species of fly. L sericata, Chr rufifacies, and C nociva larvae implanted on treated animals had significantly (P < 0.05) longer time to first strike than did L cuprina larvae. 相似文献
