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71.
Mellor DJ Stafford KJ Todd SE Lowe TE Gregory NG Bruce RA Ward RN 《Australian veterinary journal》2002,80(4):228-233
AIM: To compare the changes in plasma concentrations of noradrenaline, adrenaline and cortisol in lambs after ring castration plus tailing and in calves after dehorning with or without prior local anaesthesia. METHODS: Male lambs were castrated and tailed with rings and calves were dehorned by amputation using a scoop with or without prior local anaesthesia. Blood samples were taken before and after treatment and plasma concentrations of noradrenaline, adrenaline and cortisol were determined. RESULTS: Castration plus tailing of lambs resulted in a rapid increase in noradrenaline concentrations, a lack of an adrenaline response and a marked increase in cortisol concentration. There were similar changes in catecholamine concentrations in calves that were dehorned both with and without local anaesthetic, with adrenaline being elevated within 5 min of treatment and noradrenaline exhibiting a more protracted response. Dehorning caused a marked cortisol increase which was reduced to control concentrations by local anaesthesia for as long as the associated nerve blockade lasted. CONCLUSIONS: The very short-lived adrenaline responses in calves were attributed to dehorning-induced nociceptor input leading to sympathetic stimulation of the adrenal medulla. The longer lasting noradrenaline responses in lambs and calves were thought be due to 'wash-out' of noradrenaline from damaged tissue associated with rings and amputation wounds, respectively. 相似文献
72.
Christine Kreuder Jonna A K Mazet Gregory D Bossart Tim E Carpenter Marcel Holyoak Marc S Elie Scott D Wright 《Journal of zoo and wildlife medicine》2002,33(1):8-15
Outbreaks of morbidity and mortality in double-crested cormorants (Phalacrocorax auritus) along Florida's Gulf Coast have occurred sporadically for at least 30 yr. During these outbreaks, the Clinic for the Rehabilitation of Wildlife, located on Sanibel Island in Florida, has admitted a substantial number of cormorants with consistent presentation of primarily neurologic clinical signs. In order to investigate the association of these outbreaks in cormorants with exposure to brevetoxin, we compared the timing of admittance of cormorants with outbreak-specific clinical signs to blooms of the brevetoxin-producing marine algae, Karenia brevis (formerly Gymnodinium breve), around Sanibel Island from 1995 through 1999. The clinic admitted 360 out of 613 cormorants with the common clinical sign of severe cerebellar ataxia in six outbreaks occurring during this period. The ataxia was characterized by a broad-based stance, truncal incoordination, hypermetric gait, and intention tremors of the head. The histopathologic findings in 10 cormorants euthanized in 1997 were mild and nonspecific. An immunohistochemical staining technique for the detection of brevetoxin in cormorants documented the uptake of brevetoxin in tissues from four cormorants admitted during an outbreak in 1997, but a modified technique used on samples from 11 cormorants admitted during a K. brevis bloom in 2000 produced indeterminate results. Admittance of cormorants with outbreak-specific clinical signs was positively correlated (P < 0.05) with concurrent concentrations of K. brevis in local water. The cross-correlation coefficient was also significant when increased K. brevis levels preceded cormorant admittances by 2, 4, 6, and 8 wk. This delay in time between K. brevis blooms and cormorant admittance and our clinical finding of neurologic abnormalities in cormorants without overt histopathologic features suggest an association between K. brevis blooms and local cormorant morbidity. 相似文献
73.
Allison D Tuttle Mark Papich Gregory A Lewbart Shane Christian Conny Gunkel Craig A Harms 《Journal of zoo and wildlife medicine》2006,37(4):567-570
The nonsteroidal antiinflammatory drug ketoprofen (KTP) is a commonly used antiinflammatory and analgesic agent in reptile medicine, but no studies documenting its pharmacokinetics in this species have been published. Ketoprofen was administered as a racemic mixture to green iguanas (Iguana iguana) intravenously (i.v.) and intramuscularly (i.m.) at 2 mg/kg. Pharmacokinetic analyses were performed and indicated that ketoprofen in iguanas administered by the intravenous route has a classical two-compartmental distribution pattern, a slow clearance (67 ml/ kg/hr) and a long terminal half-life (31 hr) compared to ketoprofen studies reported in mammals. When delivered by the intramuscular route, bioavailability was 78%. These data indicate the daily dosing that is generally recommended for reptile patients, as an extrapolation from mammalian data, may be more frequent than necessary. 相似文献
74.
75.
We examine the decision to plant trees and level of tree planting for two sites, public microdam areas and household agricultural
land, and two species groups in Tigray, Ethiopia. Both sites are not perfect substitutes, as they vary with respect to distance
from the household and tenure security. The role of permanent pooled water irrigation microdams to tree planting is important
but unknown, because water borne diseases, which may influence household income and productivity, are thought to be enhanced
by the dams. We find both disease and microdams to be important predictors to tree planting. Disease seems more important
in determining whether households plant at all, and less important in the level of planting for those that do plant. For example,
disease increases the probability of planting both eucalyptus and other species groups on household-own land, but households
suffering from malaria plant higher-cost eucalyptus trees with lower probability at both sites, while planting of other lower-cost
species increases at dam sites where other villagers can monitor the trees. We also establish a connection between planting
and agricultural residues, finding a strong substitution effect on own-land. Microdam access and age are also important. Households
living nearer to dam sites will plant both species groups there with higher probabilities, but the decision to plant on agricultural
own-land is not affected. For older dams with more developed irrigation, households are more likely to grow crops rather than
plant trees on their own land, but they plant more trees at the dam sites.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
76.
Relationships of dead wood patterns with biophysical characteristics and ownership according to scale in Coastal Oregon,USA 总被引:1,自引:0,他引:1
Dead wood patterns and dynamics vary with biophysical factors, disturbance history, ownership, and management practices; the
relative importance of these factors is poorly understood, especially at landscape to regional scales. This study examined
current dead wood amounts in the Coastal Province of Oregon, USA, at multiple spatial scales. Objectives were to: (1) describe
current regional amounts of several characteristics of dead wood; (2) compare dead wood amounts across ownerships; (3) determine
the relative importance, according to spatial scale, of biophysical and ownership characteristics, to regional dead wood abundance.
Dead wood plot data were evaluated with respect to explanatory variables at four spatial scales of resolution: plots, subwatersheds,
watersheds and subbasins. The relationships of dead wood characteristics with biophysical attributes and ownership were diverse
and scale-specific. Region-wide dead wood abundance and types varied among ownerships, with public lands typically having
higher amounts of dead wood and more large dead wood than private lands. Regression analysis of total dead wood volume indicated
that ownership was important at the subbasin scale. Growing season moisture stress was important at plot, subwatershed, and
watershed scales. Topography was important at the two coarser scales. Multivariate analysis of dead wood gradients showed
that ownership was important at all scales, topography at the subbasin scale, historical vegetation at watershed and subbasin
scales, and current vegetation at plot and subwatershed scales. Management for dead wood and related biodiversity at watershed
to landscape scales should consider the distinct dynamics of snags and logs, the importance of historical effects, and the
relevance of ownership patterns. 相似文献
77.
Gregory P. Lewis Jennifer D. Mitchell C. Brannon Andersen Dennis C. Haney Min-Ken Liao Kenneth A. Sargent 《Water, air, and soil pollution》2007,182(1-4):303-323
Naturally high total dissolved solids and upstream agricultural runoff often mask the influence of urban land cover on stream chemistry and biology. We examined the influence of headwater urbanization on the water chemistry, microbiology, and fish communities of the Big Brushy Creek watershed, a 96 km2 drainage basin in the piedmont of South Carolina, USA. Concentrations of most major anions and cations (especially nitrate, sulfate, chloride, sodium, potassium, and calcium) were highest in the urban headwaters and decreased downstream. Generally, the highest concentrations of suspended coliform bacteria occurred in the urban headwaters. In contrast, stream habitat quality and the abundance, species richness, and species diversity of fishes did not differ significantly between urban and rural sites. Discharge of wastewater treatment plant effluent at one rural location caused an increase in concentrations of many solutes and possibly the abundance of benthic algae. We hypothesize that atmospheric dry deposition and domestic animal wastes are important sources of stream solutes and of coliform bacteria, respectively, in the urban headwaters. The lack of significant differences in fish abundance and diversity between urban and rural sites may indicate that urban development in the Big Brushy Creek watershed has not yet degraded habitat conditions greatly for stream fishes. Alternatively, agriculture or other land uses may have degraded stream habitat quality throughout the watershed prior to urbanization. 相似文献
78.
Coleman JN Lotya M O'Neill A Bergin SD King PJ Khan U Young K Gaucher A De S Smith RJ Shvets IV Arora SK Stanton G Kim HY Lee K Kim GT Duesberg GS Hallam T Boland JJ Wang JJ Donegan JF Grunlan JC Moriarty G Shmeliov A Nicholls RJ Perkins JM Grieveson EM Theuwissen K McComb DW Nellist PD Nicolosi V 《Science (New York, N.Y.)》2011,331(6017):568-571
If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS(2) and MoS(2) effectively reinforce polymers, whereas WS(2)/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties. 相似文献
79.
Zuber MT Smith DE Phillips RJ Solomon SC Neumann GA Hauck SA Peale SJ Barnouin OS Head JW Johnson CL Lemoine FG Mazarico E Sun X Torrence MH Freed AM Klimczak C Margot JL Oberst J Perry ME McNutt RL Balcerski JA Michel N Talpe MJ Yang D 《Science (New York, N.Y.)》2012,336(6078):217-220
Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history. 相似文献
80.