Hemoxygenase-2 is an oxygen sensor for a calcium-sensitive potassium channel

Modulation of calcium-sensitive potassium (BK) channels by oxygen is important in several mammalian tissues, and in the carotid body it is crucial to respiratory control. However, the identity of the oxygen sensor remains unknown. We demonstrate that hemoxygenase-2 (HO-2) is part of the BK channel complex and enhances channel activity in normoxia. Knockdown of HO-2 expression reduced channel activity, and carbon monoxide, a product of HO-2 activity, rescued this loss of function. Inhibition of BK channels by hypoxia was dependent on HO-2 expression and was augmented by HO-2 stimulation. Furthermore, carotid body cells demonstrated HO-2-dependent hypoxic BK channel inhibition, which indicates that HO-2 is an oxygen sensor that controls channel activity during oxygen deprivation.     

Efficacy of avermectin B1 given orally against equine intestinal strongyles and Onchocera microfilaria

Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less than 0.01) decrease in mean strongyle egg counts 14, 28, 42 and 56 d after treatment. Avermectin B1 therapy resulted in significant (P less than 0.01) decreases in mean strongyle egg counts 14, 28 and 42 d after treatment. All horses given ivermectin or avermectin B1 had zero strongyle egg counts 14 and 28 d after treatment. Fenbendazole failed to significantly decrease strongyle egg counts. Both ivermectin and avermectin B1 resulted in zero microfilaria counts in all horses 14 d after treatment. On day 70 the percentage decrease in microfilaria counts were 100% and 99.6% respectively. Fenbendazole failed to significantly decrease microfilaria counts. The oral administration of this formulation of avermectin B1 appeared to be highly efficacious against intestinal strongyles and Onchocera microfilaria. The duration of anti-strongyle activity was, however, significantly (P less than 0.01) shorter than that of ivermectin paste.     

Surgical resection of a dysgerminoma in a mare

A mare was referred for further evaluation of a mass found in the left caudal abdomen during a routine postpartum reproductive palpation. The mare was clinically normal with no history of health problems. Ultrasonographic examination of the mass confirmed its presence, but the origin of the mass could not be accurately determined. Routine haematology and serum biochemistry results were within normal limits. The mare was initially treated conservatively with antibiotics, but the mass continued to increase in size, so it was surgically excised. The mass involved the left ovary. The mare showed transient abdominal pain after surgery, but developed no other complications and was in foal 7 months later. On histology, the mass was diagnosed as a dysgerminoma, a rare ovarian tumour of germ cell origin.     

Reproductive performance in South Australian dairy herds

SUMMARY Herd breeding records (161) were examined from a random 10% sample of dairy farms (96) in South Australia with more than 40 cows and suitable breeding records for 1988 and/or 1989. Of these farms, 53 (55.2%) had a year-round calving pattern, 42 (43.8%) claimed to be seasonal and one was changing from a year-round to a seasonal pattern. Only 14.6% of farmers observed oestrous behaviour outside milking times and 18.8% used tailpaint. Overall, the average proportion of unobserved heats was estimated to be 32%. Artificial insemination (AI) was carried out on 85.4% of farms (16.7% used AI alone and 68.7% also used bulls) of which 32.9% used commercial technicians and 67.1% were do-it-yourself operators. Overall, the average 30-day submission rate was 59.9% and the average 49-day non-return to service rate was 58.9%. Investigation into the probable causes of suboptimal reproductive performance gave a tentative diagnosis of inefficient oestrous detection, deferral of service, inadequate nutrition, poor AI technique, insufficient bulls, and venereal/other diseases in 69.1, 32.1, 27.2, 28.4, 13.6 and 7.4% of records, respectively.     

Agricultural Impacts on Lake and Stream Water Quality in Grand Lake St. Marys, Western Ohio

Agricultural activities release variable products into air, soil and water ecosystems. The study was conducted to evaluate the impact of agriculture and concentrated livestock operations on stream and lake water quality in Grand Lake St. Marys watershed of north-western Ohio. Temporal water samples from the lake and the 6 feeding streams were collected bimonthly from January 2005 to May 2007, processed and measured for temperature, turbidity, pH, electrical conductivity (E _C), ammonium $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ , nitrate $\left( {{\text{NO}}_{\text{3}}^ - } \right)$ , dissolved phosphorus (P), ultra-violet (UV) light absorption, and dissolved oxygen (DO), employing standard methods of analysis. The measured data were normalized and integrated into a simple index (WQ_Index) to evaluate overall water quality. Results showed that over 90% of the area in the watershed was under cropland with associated livestock operations. With a land area equal to 195 km² represented by the six major tributaries, the average animal density was over 240 units km^?2. As a result, land disposal of manure from confined feedings operations and direct deposit by grazing animals contributed to non-point sources of water pollution. While $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ and P concentration, turbidity, and UV absorption peaked during the summer, the $\left( {{\text{NO}}_{\text{3}}^ - } \right)$ and DO concentration in both stream and lake water was lowest in the summer. Water sampled from the Coldwater, Beaver and Prairie creeks had higher turbidity, $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ , and P than other creeks. However, DO concentration and UV absorption of water did not change significantly by the influence of streams. The WQ_Index peaked in both streams and lake water with greater water quality degradation in Beaver and Coldwater creek than other creeks. A significant relationship of WQ_Index with UV absorption and P accounted 84 to 90% of the variations in stream and lake water quality degradation. However, a strong linear relationship (r ²?=?0.81; p<0.01) between UV absorption and P concentration suggested a major contribution of P to the degradation of stream and lake water quality through algal blooming and associated eutrophication.