Timber harvesting alters soil carbon mineralization and microbial community structure in coniferous forests

Timber harvesting influences both above and belowground ecosystem nutrient dynamics. Impact of timber harvesting on soil organic matter (SOM) mineralization and microbial community structure was evaluated in two coniferous forest species, ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta). Management of ponderosa pine forests, particularly even-aged stand practices, increased the loss of CO₂-C and hence reduced SOM storage potential. Changes in soil microbial community structure were more pronounced in ponderosa pine uneven-aged and heavy harvest stands and in lodgepole pine even-aged stand as compared to their respective unmanaged stands. Harvesting of trees had a negative impact on SOM mineralization and soil microbial community structure in both coniferous forests, potentially reducing coniferous forest C storage potential.     

Influence of enhanced malate dehydrogenase expression by alfalfa on diversity of rhizobacteria and soil nutrient availability

Transgenic alfalfa over-expressing a nodule-enhanced malate dehydrogenase (neMDH) cDNA and untransformed alfalfa plants were grown at the same field site and rhizosphere soils collected after 53 weeks of plant growth. These alfalfa lines differ in the amount and composition of root organic acids produced and exuded into the rhizosphere. Nucleotide sequencing of PCR-based 16S ribosomal DNA (rDNA) clone libraries and Biolog™ GN microtiter plates were employed to assess the activity of naturally occurring rhizobacteria in the two alfalfa rhizospheres. Selected macro- and micro-elements in the two alfalfa rhizosphere soils were also measured. Analysis of 240 16S rDNA clone sequences indicated the existence of about 11 bacterial phyla and their major subdivisions in the two alfalfa rhizosphere samples. There were qualitative changes in the abundance of bacterial phylogenetic groups between rhizosphere soils of transgenic and untransformed alfalfa. Carbon substrate utilization profiles suggested that rhizosphere samples from transgenic alfalfa had significantly greater microbial functional diversity compared with rhizosphere samples from untransformed alfalfa. The concentrations of nitric acid extractable P, K, Mn, Zn and Cu increased significantly in the transgenic alfalfa rhizosphere compared with the untransformed alfalfa rhizosphere. These observations indicate that organic acids produced by plant roots significantly influence rhizosphere microbial diversity and availability of macro- and micro-nutrients and demonstrate the utility of such trangenic plants as tools for studying the potential impact of plant root exudates on soil microbial ecosystems.     

The effects of extubation with an inflated versus deflated endotracheal tube cuff on endotracheal fluid volume in the dog

Objective The purpose of this study was to investigate the effect of extubation with the endotracheal tube (ETT) cuff inflated versus deflated on endotracheal fluid volume in normal canine cadavers. Study Design Prospective randomized blinded controlled cadaver study. Animals Sixteen adult Beagle cadavers weighing 10.7 ± 1.7 kg (mean ± SD) and <2 years of age. Methods Cadavers were orotracheally intubated in lateral recumbency, and the ETT cuffs were inflated to a closing pressure of 20 cm H₂O before barium was introduced orad to the cuff. The dogs were randomly assigned to an ETT cuff extubation condition of deflated or unchanged from the original closing pressure. After extubation, lateral thoracic radiographs of the cadavers were obtained and scored by three independent blinded reviewers. Each reviewer ordered all 16 lateral radiographs from most to least intratracheal contrast and also estimated residual intratracheal contrast volume. Results Dogs extubated with a deflated ETT cuff had a median rank of 13 and dogs extubated with an inflated ETT cuff had a median rank of 4.5 (p < 0.0001). Dogs extubated with a deflated ETT cuff had an estimated intratracheal volume of fluid of 1.8 mL ± 0.7 mL (mean ± SD) and dogs extubated with an inflated ETT cuff had an estimated volume of 0.9 mL ± 0.5 mL (p < 0.0001). Fleiss Kappa for agreement among evaluators was 0.875. Conclusions and clinical relevance Extubation with the cuff inflated removed more liquid contents from the trachea than extubation with the cuff deflated and may assist in the prevention of pulmonary aspiration when fluid is present in the proximal trachea. The technique did not remove all fluid so the potential for pulmonary damage remains.     

Relations among synovial membrane histopathologic findings, synovial fluid cytologic findings, and bacterial culture results in horses with suspected infectious arthritis: 64 cases (1979-1987)

A retrospective evaluation of 64 cases of suspected infectious arthritis in horses was undertaken to determine the relations among histopathologic findings in synovial membrane specimens, cytologic findings in synovial fluid samples, and bacterial culture results. Positive cultures were obtained from 55% of the joints, and 18 different bacterial organisms were cultured. Culturing of synovial fluid yielded bacterial growth more often than did culturing of synovial membrane. Histologic evaluation (H&E and Gram stain) of synovial membrane specimens provided little information to help distinguish infected from culture-negative joints. We do not advocate the routine use of closed synovial biopsy in suspected cases of equine septic arthritis.     

A proposed modulatory role of the endocannabinoid system on adipose tissue metabolism and appetite in periparturient dairy cows

To sustain the nutrient demands of rapid fetal growth, parturition, and milk synthesis, periparturient dairy cows mobilize adipose tissue fatty acid stores through lipolysis. This process induces an inflammatory response within AT that is resolved as lactation progresses; however, excessive and protracted lipolysis compounds the risk for metabolic and inflammatory diseases. The suppression of lipolytic action and inflammation, along with amplification of adipogenesis and lipogenesis, serve as prospective therapeutic targets for improving the health of periparturient dairy cows. Generally, the activation of cannabinoid receptors by endocannabinoids enhances adipogenesis and lipogenesis, suppresses lipolysis, and increases appetite in mammals. These biological effects of activating the endocannabinoid system open the possibility of harnessing the endocannabinoid system through nutritional intervention in dairy herds as a potential tool to improve dairy cows' health, although much is still to be revealed in this context. This review summarizes the current knowledge surrounding the components of the endocannabinoid system, elaborates on the metabolic effects of its activation, and explores the potential to modulate its activity in periparturient dairy cows.     

Primary teat neoplasia in two yearling heifers

Two yearling heifers developed rapidly growing soft tissue masses attached to the base of the right hind teat. In each heifer, the solitary mass was raised, firm, and attached to the overlying skin. En bloc removal was accomplished in each by positioning the heifer in dorsal recumbency and by using local infiltration analgesia. Histologic examination revealed one of the masses to be fibroma and the other, fibrosarcoma. Neither tumor has recurred, and normal function of the teat was retained.     

Economic decisions in veterinary practice: a method for field use

A technique is presented that allows economic decision analysis, sensitivity analysis, and threshold analysis to be done rapidly in field situations. The method allows the practitioner to choose between 2 interventions with different costs and different probabilities of success. A graphic approach is presented, which speeds and simplifies the analysis.     

Arteriovenous differences for glutamine in the equine gastrointestinal tract.

Glutamine has been shown to be an important metabolic substrate of enterocytes in many animals, including cats, dogs, hamsters, human beings, monkeys, rabbits, rats, and sheep. To determine whether glutamine is important in the metabolism of cells of the equine gastrointestinal tract, we examined transintestinal differences in glutamine concentrations in the arterial and venous circulation, and measured activity of the major glutamine catabolizing enzyme, glutaminase. Arteriovenous differences provide an index of the amount of a given substrate removed by the tissue across which the measurements are made, and commonly are expressed as a percentage of substrate removed, or percent extraction. Arteriovenous differences for glutamine were determined in 7 anesthetized adult horses (weight, 450 to 500 kg) before and after an i.v. glutamine infusion. The mean baseline arterial glutamine concentration (+/- SEM) was 572 +/- 24 microM; this concentration quadrupled (to 2,167 +/- 135 microM, P less than 0.01) 1 minute after i.v. bolus infusion of a 17.5-g glutamine load. Baseline extraction by the portal-drained viscera was 7.5 +/- 1.5%; this value increased to 18 +/- 2% at 1 minute (P less than 0.01) and had returned to baseline values 60 minutes later. Arteriovenous differences were greatest across the jejunum (11.8 +/- 1.8% in the baseline period vs 33.1 +/- 3.1% at 1 minute, P less than 0.001), with smaller differences across the colon, suggesting that the jejunum was the more avid utilizer of glutamine. Glutaminase activity was 4.38 +/- 0.16 and 4.00 +/- 0.60 mumol/mg of protein/h under standard conditions in jejunal and ileal mucosa, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adverse reactions following administration of an ionic iodinated contrast media in anesthetized dogs

This retrospective study was conducted to identify hemodynamic alterations associated with the administration of an ionic iodinated contrast media in dogs. Case records of 49 dogs that were anesthetized for computed tomography scanning were reviewed. Values for heart rate (HR) and direct arterial pressure were obtained. Overall, 37% of dogs had a ≥20% change in either HR or systolic arterial pressure from baseline values. Four dogs (8%) became tachycardic and two dogs (4%) became bradycardic. Eight dogs (16%) became hypertensive and two dogs (4%) became hypotensive. A significant proportion of dogs experienced changes in HR and blood pressure following IV administration of an ionic iodinated contrast media under general anesthesia.