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131.
132.
OBJECTIVE: To compare the responses of equine digital arteries (EDAs) and equine digital veins (EDVs) to endothelin-1 (ET-1) and determine the role of the endothelium and type of receptors involved in the modulation and mediation of those responses, respectively. SAMPLE POPULATION: 5 to 9 palmar digital vessels/experiment from 28 healthy horses. PROCEDURE: Rings of dissected vessels were mounted under tension between force transducer wires in organ baths containing Krebs-Henseleit solution at 30 degrees C. Responses of EDAs and EDVs (with intact [+e] or denuded [-e] endothelium) to cumulative concentrations of ET-1 (10(-10) to 3 X 10(-7) M) were compared. For (+e)EDAs and (+e)EDVs precontracted with a thromboxane-mimetic (U44069; 10(-8) M) and (-e)EDAs and (-e)EDVs, responses to an ETB receptor agonist (S6c; 10(-10) to 3 X 10(-7) M) were evaluated. Responses to ET-1 (10(-7) M) in (-e)EDAs and (-e)EDVs were evaluated after incubation with an ETA receptor antagonist (BQ-123; 3 X 10(-7) M), an ETB receptor antagonist (BQ-788; 3 X 10(-7) M), or vehicle solution. RESULTS: Endothelin-1 induced a concentration-dependent contraction of endothelium-intact and -denuded EDAs and EDVs; EDVs were more sensitive. Neither vessel type relaxed in response to S6c, although 2 of the (-e)EDAs contracted mildly. Whereas BQ-123 inhibited the (-e)EDA and (-e)EDV responses to ET-1, BQ-788 had no effect. CONCLUSIONS AND CLINICAL RELEVANCE: Endothelin-1 induced digital vasoconstriction (marked constriction in veins). This action was unaffected by endothelium and mediated predominantly by ETA receptors. These findings suggest ET-1 can induce selective digital venoconstriction. 相似文献
133.
Three non-steroidal anti-inflammatory drugs (NSAIDs), flunixin, ketoprofen and carprofen, were used in conjunction with ceftiofur, in the treatment of naturally occurring bovine respiratory disease. Sixty-six mixed-breed beef cattle weighing on average 197 kg met the inclusion criteria of pyrexia of at least 40 degrees C, an illness score indicating at least moderate illness and at least moderate dyspnoea. They were allocated randomly to four treatment groups. All the groups received ceftiofur for three days at a dose rate of 1.1 mg/kg by intramuscular injection, and three groups received, in addition, a single dose of either flunixin (2.2 mg/kg by intravenous injection) or ketoprofen (3 mg/kg by intravenous injection) or carprofen (1.4 mg/kg by subcutaneous injection). During the first 24 hours of the study, the pyrexia of the three groups treated with a NSAID was reduced significantly more than the pyrexia of the group treated with ceftiofur alone, and two and four hours after treatment the reduction in pyrexia was significantly greater in the groups treated with flunixin and ketoprofen than in the group treated with carprofen. There were no statistically significant differences between the four groups with respect to depression, illness scores, dyspnoea or coughing. There was less lung consolidation in the three groups treated with a NSAID than in the animals treated with ceftiofur alone, but the difference was significant only in the group treated with flunixin. 相似文献
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135.
The relationships between sexual and aggressive behaviors and levels of plasma testosterone and luteinizing hormone (LH) were examined in Hereford bulls at 18 and 24 mo of age. Concentrations of hormones in bulls during periods of sexual rest (13 blood samples collected from each animal during a 24-h period) were compared with individual differences in sexual and aggressive behaviors when exposed to restrained females, either individually or in groups. Nearly all correlation coefficients were low and nonsignificant. It was concluded that individual differences in sexual performance and aggressive behavior cannot be predicted based on circulating levels of testosterone and LH in bulls during periods of sexual rest. 相似文献
136.
Endris RG Hair JA Katz TL Zobre E Pennington RG Meyer JA 《Veterinary therapeutics : research in applied veterinary medicine》2002,3(4):435-440
Twenty-five dogs were evenly and randomly allocated by weight to five treatment groups: untreated control, 2 ml 65% permethrin (dogs weighing 15 to 29 kg, "average dogs"), and 2, 3, or 4 ml 65% permethrin (dogs weighing > or = 30 kg, "big dogs"). Each dog was infested with 125 unfed, adult cat fleas, Ctenocephalides felis, and 50 unfed, adult brown dog ticks, Rhipicephalus sanguineus, on Days -3 (ticks only), -2 (fleas only), 3, 7, 14, 17, 21, 24, and 28. Fleas and ticks were counted 1 and 3 or 4 days after each infestation. The duration of efficacy (defined as >90%) against C. felis was 28 to 31 days. The efficacy against fleas 31 days after application of 2, 3, or 4 ml on big dogs ranged from 79.1% (2 ml) to 100% (4 ml). Big dogs that received either 3 or 4 ml of 65% permethrin had significantly (P < or = .05) fewer fleas at several evaluations between 15 and 31 days after treatment. The duration of efficacy against R. sanguineus was 15 (2 ml for big dogs) to 28 (2 ml for average dogs) days. The efficacy against R. sanguineus 28 days after treatment ranged from 79.1% (2 ml on big dogs) to 94.1% (2 ml on average dogs). Significantly (P < or = .05) fewer ticks were present at several evaluations after treatment on big dogs that received 3 or 4 ml than were present on big dogs treated with 2 ml. No significant differences were detected between the 3- and 4-ml groups from Days 10 to 31; however, the geometric mean number of ticks in the group treated with 4 ml was numerically lower than that for dogs treated with 3 ml on several occasions. These data indicate that a dose volume of 3 or 4 ml of 65% permethrin is needed to obtain an adequate level and duration of efficacy against both C. felis and R. sanguineus on dogs weighing 30 kg or more. 相似文献
137.
John W. Liebeschuetz Ruth B. Katz Albert D. Duriatti Mary L. Arnold 《Pest management science》1997,50(3):258-274
A previous investigation established that compounds containing a guanidinium or amidinium grouping are effective inhibitors of sterol Δ8–Δ7 isomerase and/or Δ14 reductase activity in plant pathogenic fungi. A binding model for known fungicidal inhibitors of this enzyme has now been used to rationally design further guanidinium or amidinium inhibitors. Three novel classes of chemistry were investigated. The results of biochemical testing against ergosterol biosynthesis in Ustilago maydis (DC) Corda and of in-vivo testing for fungicidal activity against Erysiphe graminis DC f. sp. hordei Marchal (powdery mildew of barley), do much to support the binding model, and compounds with significant fungicidal activity have been found. © 1997 SCI. 相似文献
138.
Axons from eyes transplanted to the tail in Xenopus larvae enter the caudal spinal cord and follow two adjacent tracts rostrally to the level of the cerebellum. When eyes are transplanted to the ear area, optic axons enter the hindbrain and follow the same tracts rostrally and caudally. These sensory pathways normally contain the embryonic sensory system of the Rohon-Beard axons and the descending and ascending tracts of nerve V. We propose that the transplanted optic axons have followed a continuous substrate sensory pathway normally shared by a number of different sensory tracts. 相似文献
139.
Control of myocardial contraction: the sensitivity of cardiac actomyosin to calcium ion 总被引:4,自引:0,他引:4
The control by calcium ion of the adenosine triphosphatase activity of cardiac actomyosin is similar to that of white skeletal actomyosin. This finding indicates that the slower contraction and relaxation of heart muscle do not reflect different levels to which free calcium ion concentration around the myofibrils must be adjusted during contraction and relaxation and suggests a mechanism whereby myocardial contractility may be regulated. 相似文献
140.
The influence of compost and zeolite co‐addition on the nutrients status and plant growth in intensively cultivated Mediterranean soils
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The main objective of the study was to test the benefits of compost and zeolite co‐addition on the fertility of organic‐rich Mediterranean soils. Previous pot study in greenhouse found that zeolites mixed with compost significantly improved potassium availability as well as exchangeable potassium capacity in the soils. To further test this finding, a field experiment was conducted using potato – Solanum tuberosum L., desiree cultivar in peat soils of the Hula Valley, Israel. Adhering to the protocol of the greenhouse experiments, the treatments included 5% compost addition with no zeolites, 2% zeolite addition without compost, co‐addition of 5% compost mixed with 2% zeolites and control. We found that compost addition increased significantly the potatoes yield and the number of large tubers; however, the zeolite addition had no impact on yield. Co‐addition of compost and zeolites did not improve total crop yield or number of large tubers compared with compost addition only. The results are consistent with nutrients availability (N, P, K) across the treatments. In a commercialized field using the experiment conditions, the 2% zeolite addition would amount to 18 ton of zeolites per hectare. Hence, we conclude that soil amendment with the tested zeolite might be beneficial to improve soil retention for cationic nutrients (e.g. K+) under high leaching systems such as plant culture in pots, but in the field with high loads of compost, its effect is minor. 相似文献