Sensitivity of boreal forest carbon balance to soil thaw

We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 +/- 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 +/- 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 +/- 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool ( approximately 150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.     

Congenital dyserythropoietic anaemia and dyskeratosis in Australian Poll Hereford calves

Congenital dyserythropoietic anaemia (CDA) is a heterogeneous group of rare genetic disorders that in humans is characterised by ineffective haematopoiesis with morphological abnormalities in erythroid precursor cells and secondary iron overload. In the 1990s, a syndrome of CDA with dyskeratosis and progressive alopecia was reported in Poll Hereford calves in Canada and the USA. We report the clinical and pathological findings in two Poll Hereford calves with this syndrome from separate properties in South Australia. The animals had a variably severe anaemia, associated with abnormal nucleated red blood cells in peripheral blood, and large numbers of rubricytes and metarubricytes with a characteristic nuclear ultrastructure in the bone marrow. Both calves were born with a wiry hair coat and a progressively ‘dirty‐faced’ appearance associated with hyperkeratosis and dyskeratosis (apoptosis).     

Effect of adenosine infusion on isoflurane MAC in dogs.

Adenosine is a potent analgesic in people and reduces the MAC of halothane in dogs. The purpose of this study was to determine whether adenosine reduces the MAC of isoflurane in dogs. Seven beagles (four males and three females) were anesthetized and randomly assigned to receive adenosine (0.3 mg kg^–1 minute^–1; 6 mL kg^–1 hour^–1, IV) or saline (0.9%, 6 mL kg^–1 hour^–1IV). After an interval of ≥7 days, each dog was reanesthetized and treated with the alternate infusion. Anesthesia was induced and maintained with isoflurane in oxygen. Dogs were intubated and instrumented for measurement of mean systemic arterial blood pressure and airway concentration of isoflurane and end‐tidal partial pressure of carbon dioxide. The MAC for isoflurane was determined using the tail‐clamp technique. Baseline MAC values were 1.25 (1.15, 1.35)% [median (minimum, maximum)] and 1.25 (1.05, 1.45)% before the saline and adenosine treatments, respectively. After 2 hours of infusion with saline or adenosine, MAC values were not different (p = 0.156) and were 1.25 (0.95, 1.35)% and 1.05 (1.00, 1.25)%, respectively. Two hours following the end of each infusion, the MAC values for saline and adenosine treatment groups differed significantly (p = 0.015), but by no more than the normal variation inherent in this study, and were 1.15 (1.15, 1.35)% and 1.05 (1.05, 1.25)%, respectively. Mean arterial blood pressure was 93 (74, 123) mm Hg for saline treated dogs and 67 (52, 72) mm Hg (p = 0.008) during adenosine infusion. End‐tidal carbon dioxide was not different between the two treatment groups. We conclude that adenosine administered at 0.3 mg kg^–1 minute^–1had no effect on isoflurane MAC in dogs, but decreased mean arterial blood pressure.     

The Current State of Solar Modeling

Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.     

Prevalence of the causes of fleece derangement among sheep flocks in New South Wales

SUMMARY An investigation of sheep flocks with unknown histories of fleece derangement, selected at random from the main sheep raising areas of New South Wales, showed that Psorergates ovis was present in 53 of the 177 flocks surveyed and In 162 of the 3495 sheep examined. Of the single causes of fleece derangement, the most prevalent was grass seed contamination (15.7%) followed by Infestation with sheep body lice, Bovicola ovis, (14.7%) and Infestation with Itch mite (7.8%). The prevalence of fleece derangement was significantly higher on sheep In which lice were the only ectoparasites found than on those In which Itch mites were the only ectoparasites present. The greatest prevalence of P ovis was In flocks In the Young, Yass, Mudgee and Tenterfield districts. In most affected flocks, more than one potential cause of fleece derangement was present. Itch mite Infestation was more prevalent in flocks that received no treatment for ectoparasites than in those that had been treated in the year preceding the survey. Our results did not support a commonly held belief among farmers that arsenical compounds control Infestations of Itch mites more effectively than other types of pesticides. There was no significant difference in prevalence of fleece derangement between flocks treated with different pesticide groups and those that received no treatment, but mean fleece derangement score was significantly lower in sheep treated with organophosphates than in untreated sheep. Infestations of lice were significantly more prevalent in sheep from flocks treated with synthetic pyrethroids than from those treated with organophosphates or those that received no treatment.     

Comparison of two insulin protocols for diabetic dogs undergoing cataract surgery

Objective To evaluate the effectiveness of two insulin doses to maintain an acceptable range of blood glucose concentrations (70–200 mg dL^?1) in the peri‐operative period in diabetic dogs. Animals Twenty‐four diabetic dogs with a median weight of 20.6 kg and a median age of 8 years old. Methods The dogs were randomly assigned to receive either 25 or 100% of their normal insulin dose subcutaneously on the morning of surgery. The anesthetic and feeding protocols were standardized. On the day before surgery, venous blood was collected for measurement of β‐hydroxybutyrate, cholesterol, glucose, glycosylated hemoglobin, hematocrit, total plasma protein and urea nitrogen. On the day of surgery, blood glucose concentrations were measured prior to anesthesia, prior to the start of surgery, 1 and 2 hours after beginning of surgery, 1 hour after extubation, at 16 : 00 hours and at 20 : 00 hours. β‐hydroxybutyrate concentrations were measured at 20 : 00 hours that day. At 08 : 00 hours the following day, β‐hydroxybutyrate and glucose concentrations were measured. The significance of differences between groups was tested with Wilcoxon's two‐tailed rank‐sum test, Chi‐square test and Fisher's exact test. Results There were no differences in insulin treatments, clinical signs, concurrent diseases and most clinicopathological parameters between the two groups of dogs at entry to the study. The 25% dose group had blood glucose values of 296 (102–601) mg dL^?1 at 16 : 00 hours and 429 (97–595) mg dL^?1 at 20 : 00 hours on the day of surgery. The 100% insulin dose group had lower corresponding values of 130 (55–375) mg dL^?1 (p = 0.04) and 185 (51–440) mg dL^?1 (p = 0.004). No other differences (p < 0.05) were detected between the two groups. Conclusions The administration of a full dose of insulin is only marginally advantageous for reducing glucose to normal (70–120 mg dL^?1) after anesthesia but neither dose consistently induced glycemic values in an acceptable range (70–200 mg dL^?1) or normoketonemia. Clinical relevance Blood glucose should be measured immediately before anesthesia and periodically throughout the peri‐operative period in all diabetic dogs because presurgical subcutaneous administration of 25 or 100% of the normal insulin dose resulted in unpredictable blood glucose concentrations.