Intravenous administration of lenperone and glycopyrrolate followed by continuous infusion of sufentanil in dogs: cardiovascular effects

Cardiopulmonary effects of IV administration of lenperone (0.44 mg/kg) and glycopyrrolate (0.11 mg/kg) were determined in 6 healthy adult (2 to 5 years) Pointers during controlled ventilation with oxygen. Sufentanil was then administered as a loading dose (5 micrograms/kg, IV) and continually infused (0.1 microgram/kg/min) for 120 minutes. Lenperone-glycopyrrolate did not significantly affect heart rate, but induced a significant decrease in systemic vascular resistance, rate-pressure product, and mean arterial pressure, and significantly increased cardiac index. Administration of sufentanil did not significantly affect mean arterial pressure. Heart rate and rate-pressure product were significantly decreased during sufentanil infusion. Systemic vascular resistance gradually increased during the 2-hour sufentanil infusion and was not significantly different from base-line values at end of study. Cardiac index was not significantly different from baseline values during sufentanil infusion, except at 90 and 120 minutes, when it was significantly less. As administered in the present study, lenperone, glycopyrrolate, and sufentanil are safe and efficacious in adult dogs.     

Dietary fiber for dogs: I. Effects of graded levels of dietary beet pulp on nutrient intake, digestibility, metabolizable energy and digesta mean retention time

The optimal level of beet pulp (BP) inclusion in a meat-based dog diet and the effects of graded levels of dietary BP on fecal excretion responses and mean retention time of marked fiber in the gastrointestinal tract of the dog were evaluated using 30 female English Pointers assigned to isonitrogenous diets containing 0, 2.5, 5.0, 7.5, 10.0 or 12.5% BP (DM basis). Beet pulp replaced portions of dietary cornstarch. Digestibilities of DM and OM decreased by an average of 6% when comparing diets containing BP to the control diet, and quadratic and cubic responses were noted in digestibilities of fiber constituents (lower values at the 7.5 and 10.0% levels, higher values at the 2.5, 5.0 and 12.5% levels). Digestible energy (DE) and ME intakes (kcal/d) were not affected by treatment, but when expressed as a percentage of GE, values decreased (4.8% for DE; 6.2% for ME) linearly with increasing BP levels. Wet weight of feces increased (from 117 to 374 g/d) linearly as percentage of dietary BP increased. Frequency of defecation was higher (P less than .05) for dogs fed the diet containing 12.5% BP than for dogs fed the other diets (5.2 vs mean value of 2.8/24 h). Mean retention time of marked fiber decreased linearly (high value of 23.4 h for the 2.5% BP treatment, low value of 13.0 h for the 10.0% BP treatment) with increased level of BP. Beet pulp levels up to 7.5% of diet DM appear acceptable as a dietary fiber source in a meat-based canine diet.     

Pleomorphic sarcoma with giant cells infiltrating the infraorbital canal in an aged Thoroughbred mare

A 27-year-old Thoroughbred mare presented for computed tomography (CT) of the head following a 3-month history of facial swelling at the infraorbital foramen, unilateral self-mutilation and head-shaking. Standing CT imaging showed soft tissue attenuation surrounding the infraorbital canal, with extensive bony lysis of the canal and maxillary bone at the infraorbital foramen. The mare was subjected to euthanasia, and post-mortem examination revealed a proliferative tan soft tissue mass overlying the infraorbital nerve. A histopathological diagnosis of pleomorphic sarcoma with giant cells was made. Immunohistochemical analysis failed to fully elucidate the mesenchymal cell of origin of the sarcoma. Pleomorphic sarcoma with giant cells involving the infraorbital canal of the horse has not been previously described. This case highlights chronic subtle behavioural changes attributable to this neoplasm prior to the development of clinical signs and the utility of advanced imaging in the diagnosis.     

Gene transposition as a cause of hybrid sterility in Drosophila

We describe reproductive isolation caused by a gene transposition. In certain Drosophila melanogaster-D. simulans hybrids, hybrid male sterility is caused by the lack of a single-copy gene essential for male fertility, JYAlpha. This gene is located on the fourth chromosome of D. melanogaster but on the third chromosome of D. simulans. Genomic and molecular analyses show that JYAlpha transposed to the third chromosome during the evolutionary history of the D. simulans lineage. Because of this transposition, a fraction of hybrids completely lack JYAlpha and are sterile, representing reproductive isolation without sequence evolution.     

The Role of Phosphorus Availability in the Response of Soil Nitrogen Cycling,Understory Vegetation and Arbuscular Mycorrhizal Inoculum Potential to Elevated Nitrogen Inputs

The impacts of increased nitrogen (N) inputs into temperate ecosystems via atmospheric nitrogen deposition on nitrogen cycling and nitrogen retention have been described in a variety of ecosystem types. The role of secondary nutrients such as phosphorus (P) in ecosystem responses to increased N inputs is less well-understood. N and P availability are likely to interact to influence ecosystem productivity and N cycling rates, and this interaction would be expected to vary as N inputs increase. Furthermore, N and P inputs may affect plant-mycorrhizal associations and the ability of arbuscular mycorrhizae (AM) to colonize roots. We added nitrogen (97 kg ha^-1 yr^-1) and phosphorus (30 kg ha^-1 yr^-1) to an oak-maple forest in southwestern Virginia (U.S.A.) from 1994 through 1996. Inorganic nitrogen concentrations, net nitrogen mineralization, net nitrification rates and arbuscular mycorrhizal inoculum potential (MIP) were assessed during the growing season in 1996. Responses of the understory vegetation and soil N cycling to N addition suggested that the ecosystem was strongly N-limited. Nitrogen cycling rates were not affected by P inputs, though P addition increased P availability and decreased MIP. It was hypothesized that P availability may have more significant influences on N cycling and the plant-mycorrhizal association in ecosystems showing stronger symptoms of nitrogen saturation. Results suggest that the use of P fertilization would be effective in alleviating P-deficiency in vegetation receiving elevated atmospheric N deposition, but perhaps at the cost of benefits that associations with arbuscular mycorrhizae provide.     

Energetic radiation produced during rocket-triggered lightning

Using a NaI(Tl) scintillation detector designed to operate in electrically noisy environments, we observed intense bursts of energetic radiation (> 10 kiloelectron volts) during the dart leader phase of rocket-triggered lightning, just before and possibly at the very start of 31 out of the 37 return strokes measured. The bursts had typical durations of less than 100 microseconds and deposited many tens of megaelectron volts into the detector. These results provide strong evidence that the production of runaway electrons is an important process during lightning.