Angiotensin Converting Enzyme in Bovine Ovarian Follicular Fluid and its Relationship with Oestradiol and Progesterone

The purpose of the present study was to identify angiotensin converting enzyme (ACE) in bovine ovarian follicular fluid and to relate the ACE activity to the phase of the oestrous cycle, pregnancy, and the follicular fluid concentrations of oestradiol and progesterone. The ACE activity was similar to that found in bovine serum and was completely inhibited by the specific ACE inhibitor captopril. The 50% inhibitory concentration (IC₅₀) was 1.4 × 10^?8 mol/l (range 0.8 × 10^?8 to 5.0 × 10^?8 mol/l; n=6), which is similar to that found in bovine and human serum. The ACE activity did not differ in the pre‐ovulatory and luteal phase, pregnancy or cystic follicles. It correlated with the follicular fluid concentration of progesterone in cycling cows (ρ=0.476; p < 0.005; n=36), but did not correlate with the diameter of the follicles, the follicular fluid concentration of oestradiol or the ratio between the oestradiol and progesterone concentrations. The demonstration of ACE in bovine ovarian follicular fluid provides further evidence for the presence of a local renin–angiotensin system in the bovine ovary.     

Sarcocystis neurona-specific immunoglobulin G in the serum and cerebrospinal fluid of horses administered S neurona vaccine

A vaccine against Sarcocystis neurona, which induces equine protozoal myeloencephalitis (EPM), has received conditional licensure in the United States. A major concern is whether the immunoglobulin G (IgG) response elicited by the vaccine will compromise the use of Western blotting (WB) as a diagnostic tool in vaccinated horses with neurologic disease. Our goals were to determine if vaccination (1) causes seroconversion: (2) causes at least a transient increase in S neurona-specific IgG in the cerebrospinal fluid (CSF); and (3) induces an IgG response that can be differentiated from that induced by natural exposure. Horses included in the study (n = 29) were older than 6 months with no evidence of neurologic disease. The presence or absence of anti-S neurona antibodies in the serum of each horse was determined by WB analysis. Seropositive horses had CSF collected and submitted for cytology, CSF index, and WB analysis. The vaccine was administered to all the horses and boostered 3-4 weeks later. On day 14 after the 2nd administration, serum and CSF were collected and analyzed. Eighty-nine percent (8 of 9) of the initial seronegative horses seroconverted after vaccination, of which 57% (4 of 7) had anti-S neurona IgG in their CSE Eighty percent (16 of 20) of the seropositive horses had an increase in serum S neurona IgG after vaccination. Of the 6 of 20 horses that were initially seropositive/CSF negative, 2 were borderline positive for anti-S neurona IgG in the CSF, 2 tested positive, and 2 were excluded because the CSF sample had been contaminated by blood. There were no WB banding patterns that distinguished samples from horses that seroconverted due to vaccination versus natural exposure. Caution must be used in interpreting WB analysis from neurologic horses that have been recently vaccinated for EPM.     

Technical note: using calcium carbonate as an osmolar control treatment for acid-base studies in horses

The efficacy of using calcium carbonate as an osmolar control treatment for acid-base studies in horses receiving alkalizing compounds was evaluated. Six mares were nasogastrically intubated with isomolar quantities of sodium or calcium as sodium bicarbonate or calcium carbonate or with water during three treatment periods. Doses of the carbonic acid salts were 500 mg/kg sodium bicarbonate mixed with 4 L of distilled water (positive control) and 595 mg/kg calcium carbonate mixed with 2 L of distilled water to yield isoosmolar treatments. Four liters of distilled water served as the negative control. Jugular venous blood samples were drawn before intubation and at hourly intervals for 6 h after intubation. The serum electrolytes Na+ and K+, blood pH, and HCO3- were determined. The sodium bicarbonate treatment increased blood pH and HCO3- (P < 0.01) above both the water and CaCO3 treatments. No differences (P > 0.05) were found between the water and CaCO3 treatments. These data indicate that calcium carbonate may serve as a suitable osmolar control treatment for studying the effects of treatments that affect acid-base status of horses.     

A landscape perspective on sustainability of agricultural systems

Agricultural sustainability considers the effects of farm activities on social, economic, and environmental conditions at local and regional scales. Adoption of more sustainable agricultural practices entails defining sustainability, developing easily measured indicators of sustainability, moving toward integrated agricultural systems, and offering incentives or imposing regulations to affect farmer behavior. Landscape ecology is an informative discipline in considering sustainability because it provides theory and methods for dealing with spatial heterogeneity, scaling, integration, and complexity. To move toward more sustainable agriculture, we propose adopting a systems perspective, recognizing spatial heterogeneity, integrating landscape-design principles and addressing the influences of context, such as the particular products and their distribution, policy background, stakeholder values, location, temporal influences, spatial scale, and baseline conditions. Topics that need further attention at local and regional scales include (1) protocols for quantifying material and energy flows; (2) standard specifications for management practices and corresponding effects; (3) incentives and disincentives for enhancing economic, environmental, and social conditions (including financial, regulatory and other behavioral motivations); (4) integrated landscape planning and management; (5) monitoring and assessment; (6) effects of societal demand; and (7) integrative policies for promoting agricultural sustainability.     

Particle track enhancement in cellulose nitrate by application of an electric field

The number and length of etchable tracks, created by alpha particles in a cellulose nitrate sheet, are significantly enhanced by the application of an electric field across the cellulose nitrate.     

Potentiation of 5-Fluorouracil Inhibition of Flexner-Jobling Carcinoma by Glucose

A significant potentiation of the antitumor action of 5-fluorouracil in rats bearing the Flexner-Jobling carcinoma is produced by the intraperitoneal administration of large doses of glucose.