Effects of grazing strategy on limiting nitrate leaching in grazed grass‐clover pastures on coarse sandy soil

Urinations of ruminants on grazed pastures increase the risk of nitrate leaching. The study investigated the effect of reducing the length of the grazing season on nitrate leaching from a coarse sandy, irrigated soil during 2006–2007 and 2007–2008. In both years, precipitation was above the long‐term mean. The experiment was initiated in a 4‐yr‐old grass‐clover sward in south Denmark. Three treatments were as follows grazing only (G), spring cut followed by grazing (CG) and both spring and autumn cuts with summer grazing (CGC). Nitrate leaching was calculated by extracting water isolates from 80 cm depth using ceramic suction cups. Because of considerable variation in measured nitrate concentrations, the 32 installed suction cups per treatment were insufficient to reveal differences between treatments. However, weighted nitrate leaching estimations for G, CG and CGC showed estimated mean nitrate N concentrations of 23, 19 and 13 mg/L for an estimated proportion area occupied by urine patches of 0.33, 0.26 and 0.16, respectively. Thus, N concentrations in G and CG exceeded the EU limit of 11.3 mg N/L. Under the prevailing conditions, the time of urination did not appear important. The estimated background leaching calculated from suction cups presumably not situated under urine patches resulted in mean nitrate N concentrations of 2.6 mg/L.     

Effect of disposition on the relative delayed neurotoxicity potency among leptophos analogs

The oxons of leptophos, its desbromo analog, and its ethoxy analog all inhibit hen brain neurotoxic esterase (NTE) to a similar degree in vitro, but have large differences in minimum effective oral doses for organophosphorus-induced delayed neurotoxicity. The potencies of leptophos and ethoxyleptophos are increased 10-fold when administered to hens intravenously (iv), but the potency of desbromoleptophos is nearly the same whether administered iv or po. Leptophos distributes nearly five times more rapidly from the central compartment than does desbromoleptophos, and its attenuated oral potency may be due to slower net absorption and/or dilution by compartments other than nervous tissue. Intravenously administered phenylphosphonothionates are excreted rapidly into the gastrointestinal tract and a large proportion of the dose is eliminated in the first 48 hr. Indirect evidence indicates that ethoxyleptophos is more rapidly degraded and ethoxyleptophos-inhibited NTE recovers more rapidly than does NTE inhibited by leptophos or desbromomleptophos. It is proposed that differential aging of ethoxyleptophos chiral isomers as well as pharmacokinetic factors may contribute to the apparently anomalous behavior of these three analogs.     

Differences between Brahman and Holstein cows in heat-shock induced alterations of protein synthesis and secretion by oviducts and uterine endometrium

Our objectives were to test differences in protein synthesis and secretion by cultured oviducts and endometrium from Brahman and Holstein cows and the response of those tissues to in vitro heat shock. Explants of oviductal tissue obtained at estrus from Holstein (n = 5) and Brahman (n = 6) cows were cultured at a homeothermic (39 degrees C) or heat shock (43 degrees C) temperature. At 6 h, cultures were pulse-chase labeled (2 h, L[4,5-3H]leucine; 2 h, L-leucine). Endometrial explants were cultured similarly except that pulse labeling was performed for the first 0 to 15, 0 to 30, 30 to 60 and 60 to 90 min following onset of heat shock. A temperature of 43 degrees C increased secretion of nondialyzable 3H-labeled macromolecules by both oviducts of Brahmans but depressed secretion by the oviduct ipsilateral to the side of ovulation of Holsteins. For both breeds, 43 degrees C decreased incorporation of [3H]leucine into trichloroacetic acid (TCA)-precipitable radioactivity in oviducts from the ipsilateral side. Secretion of 3H-labeled macromolecules by pulse-labeled endometrial explants increased at 43 degrees C. Heat shock caused an immediate increase in TCA-precipitable radioactivity in tissue during pulse labeling for Holstein tissues. Incorporation was decreased at 43 degrees C in tissue from Brahmans in the first 30 min and increased thereafter. Incorporation of [3H]thymidine by endometrial explants from Brahmans was increased at 43 degrees C, whereas it was suppressed at 43 degrees C in explants from Holstein cows. Heat shock proteins of 72,000 and 90,000 molecular weight were present in endometrial tissues. A major secretory product of endometrium had a molecular weight of 57,500 for Brahmans and a lower molecular weight (55,600) for Holsteins.     

Influence of gibberellic acid and stock plant irradiance on carbohydrate content and rooting in cuttings of Scots pine seedlings (Pinus sylvestris L.)

Seedlings of Pinus sylvestris L. were grown at three different irradiances (12, 30, or 60 W m(-2)) under a 17 h photoperiod. After six weeks, cuttings were excised and rooted at 30 W m(-2). Gibberellic acid (GA(3), 5 microl of 2 x 10(-4) or 2 x 10(-3) M) was applied to each cutting immediately after excision. Cuttings from stock plants grown at the low irradiance rooted most quickly, whereas the highest number of roots per cutting was obtained in cuttings from stock plants grown at 30 W m(-2). Gibberellic acid delayed rooting and reduced the number of roots in cuttings from stock plants grown at 12, 30, or 60 W m(-2). The initial carbohydrate content of cuttings increased with stock plant irradiance. For all carbohydrates, except myoinositol and an unknown inositol derivative, the content per cutting increased during the first 28 days of rooting. The GA(3) treatment significantly reduced the starch content of cuttings during the rooting period, but did not significantly change the content of ethanol soluble carbohydrates.     

Phytophthora cambivora in Oregon and its pathogenicity to Chrysolepis chrysophylla

A new canker disease causing mortality of golden chinquapin trees [Chrysolepis chrysophylla (Dougl.) Hjelmqvist], in Oregon was recently observed. Most of the symptomatic or dead trees were located near roads. The cankers on the lower boles of trees are similar to those caused by species of Phytophthora on other trees in western North America. The cankers in the inner bark were reddish‐orange in colour and extended upward from necrotic roots. Phytophthora cambivora (Petri) Buisman was isolated from the cankers; identity was confirmed by morphological comparison with known isolates and internal transcribed spacer sequence analysis. Pathogenicity was confirmed by inoculation of chinquapin seedlings and mature trees. Seven of nine isolates from chinquapin were A2 mating type; 27 of 28 isolates from other hosts in Oregon and Washington were A1 mating type.     

INTER‐ AND INTRAFRACTION MOTION FOR STEREOTACTIC RADIOSURGERY IN DOGS AND CATS USING A MODIFIED BRAINLAB FRAMELESS STEREOTACTIC MASK SYSTEM

Precise and accurate patient positioning is necessary when doing stereotactic radiosurgery (SRS) to ensure adequate dosing to the tumor and sparing of normal tissues. This prospective cross‐sectional study aimed to assess feasibility of a commercially available modified frameless SRS positioning system for use in veterinary radiotherapy patients with brain tumors. Fifty‐one dogs and 12 cats were enrolled. Baseline and verification CT images were acquired. The verification CT images from 32 dogs and five cats had sufficient images for fusion to baseline CT images. A rigid box‐based fusion was performed to determine interfraction motion. Forty‐eight dogs and 11 cats were assessed for intrafraction motion by cine CT. Seventy percent of dogs and 60% of cats had interfraction 3D vector translational shifts >1 mm, with mean values of 1.9 mm in dogs, and 1.8 mm in cats. In dogs muscle wasting was weakly correlated with translational shifts. The maximum angular interfraction motion observed was 6.3° (roll), 3.5° (pitch), and 3.3° (yaw). There was no correlation between angular interfraction motion and weight, brachycephaly, or muscle wasting. Fifty‐seven percent of dogs and 50% of cats had respiration‐related intrafraction motion. Of these, 4.5% of dogs and 10% of cats had intrafraction motion >1 mm. This study demonstrates the modified Brainlab system is feasible for SRS in dogs and cats. The smaller cranial size and difference in anatomy increases setup uncertainty in some animals beyond limits usually accepted in SRS. Image‐guided positioning is recommended to achieve clinically acceptable setup accuracy (<1 mm) for SRS.