Enzyme Immunoassays for the Determination of Ovine LH and FSH

The development of competitive enzyme immunoassays for ovine plasma LH (oLH) and FSH (oFSH) is described. Standards and plasma samples were preincubated with diluted antiserum to oLH or oFSH and the reacted solution (100 μl per well) was transferred to plates previously coated with oLH or oFSH, respectively. The second antibody used was anti‐rabbit IgG horseradish peroxidase. The measuring range was 0.39–50 ng/ml for each hormone and the 50% relative binding sensitivity was 9 ng/ml for oLH. The respective value for oFSH was 3.5 or 34 ng/ml with different hormone and antibody preparations used for the assay. The enzyme immunoassays were used to determine oLH and oFSH levels in plasma from ewes of two breeds during the oestrous cycle. The assays detected the first FSH surge coincident with the LH surge, the second FSH surge about 24 h later and the periodic fluctuations of FSH concentrations during the luteal phase of the oestrous cycle. These enzyme immunoassays are an efficient and economic alternative to the established radioimmunoassays (RIA) for oLH and oFSH.     

Organochlorine insecticide problems in livestock

1. Antidotal therapy for acute OC intoxications is symptomatic and supportive. Use sedatives to control convulsions and AC to adsorb any pesticide remaining in the gut, and wash topical exposures. 2. Published kinetics should be applied to field situations with caution. In general, residues decline relatively quickly immediately following the last exposure; thereafter, the rate slows considerably. The elimination-rate constant and, hence, the half-life of any given OC is dependent on many variables that usually are not known under field conditions. This fact may result in serious errors if literature values are relied on too heavily in predicting the outcome of "natural" contamination. As a rule of thumb, elimination data derived from animals experimentally fed to plateau concentrations may be regarded as fairly conservative for such purposes, if the contaminated animals are maintained in a normal fashion. Probably the least risky method of predicting return to marketability is using frequent samples, taken at regular intervals (for example, 1 to 2 weeks) during the first month after last exposure, to adjust literature values. 3. Residues from larger dosages and shorter exposures tend to be smaller in proportion to dose and are eliminated more quickly than those resulting from longer exposures and smaller doses. 4. Activated charcoal is of universal benefit only if given immediately after exposure. 5. Pharmaceutical modifiers of xenobiotic metabolism such as phenobarbital are of very limited value. The particular type and amount of residual OC and the potential economic benefit of therapy should be considered thoroughly before undertaking such therapy. In most cases, the expense won't be justified. 6. Mineral oil increases the fecal excretion of some OC. Fecal excretion, however, is so small in relation to total body burdens that even a several-fold increase may not be useful economically except when residue concentrations are low to start with. 7. Nutritional strategies have the advantage of being very cheap. Practitioners should remember, however, that tissue concentrations actually may increase as body fat decreases. The costs of maintaining animals for an extra 6 to 10 months should be considered before undertaking such an effort.(ABSTRACT TRUNCATED AT 400 WORDS)     

Histochemical demonstration of copper and copper-associated protein in the canine liver

Three different histochemical methods for copper detection were compared. Atomic absorption analysis was used to substantiate the tissue stains. There was good correlation between rhodanine staining and rubeanic acid-stained tissue sections. The orcein reaction for copper-associated protein did not consistently correlate with the methods demonstrating copper. Prolonged staining (72 hours) with rubeanic acid more consistently and clearly detected increased copper in canine livers than did staining with rhodanine. Seventy-two hour staining with rubeanic acid is the method of choice for histochemical detection of copper in canine liver.     

The Control of Reactive Oxygen Species Influences Porcine Oocyte In Vitro Maturation

The aim of this study was to examine the effect of varying intracellular reactive oxygen species (ROS) levels during oocyte in vitro maturation with enzymatic ROS production systems (xanthine + xanthine oxidase or xanthine + xanthine oxidase + catalase), scavenger systems (catalase or superoxide dismutase + catalase) or cysteine on porcine oocyte maturation. Oocyte ROS levels showed an increase when H₂O₂ or O₂?^‐ production systems were added to the culture medium (p < 0.05). On the other hand, the presence of ROS scavengers in the maturation medium did not modify oocyte ROS levels compared with the control after 48 h of maturation, but the addition of cysteine induced a decrease in oocyte ROS levels (p < 0.05). The ROS production systems used in this work did not modified the percentage of oocyte nuclear maturation, but increased the decondensation of sperm head (p < 0.05) and decreased the pronuclear formation (p < 0.05). In turn, the addition of O₂?^‐ and H₂O₂ scavenging systems during in vitro maturation did not modify the percentage of oocytes reaching metaphase II nor the oocytes with decondensed sperm head or pronuclei after fertilization. However, both parameters increased in the presence of cysteine (p < 0.05). The exogenous generation of O₂?^‐ and H₂O₂ during oocyte in vitro maturation would not affect nuclear maturation or later sperm penetration, but most of the spermatozoa cannot progress to form the pronuclei after fusion with the oocyte. The decrease in endogenous ROS levels by the addition of cysteine would improve pronuclear formation after sperm penetration.     

Phosphofructokinase and Malate Dehydrogenase Participate in the In Vitro Maturation of Porcine Oocytes

Oocyte maturation depends on the metabolic activity of cumulus–oocyte complex (COC) that performs nutritive and regulatory functions during this process. In this work, the enzymes [phosphofructokinase (PFK) and malate dehydrogenase (MDH)] were tested to elucidate the metabolic profile of porcine COCs during the in vitro maturation (IVM). Enzymatic activity was expressed in U/COC and U/mg protein (specific activity) as mean ± SEM. In vitro maturation was performed with 2‐oxoglutarate (5, 10 and 20 mm ) or hydroxymalonate (30, 60 and 100 mm ) inhibitors of PFK and MDH, respectively. The PFK and MDH activities (U) remained constant during maturation. For PFK, the U were (2.48 ± 0.23) 10^?5 and (2.54 ± 0.32) 10^?5, and for MDH, the U were (4.72 ± 0.42) 10^?5 and (4.38 ± 0.25) 10^?5 for immature and in vitro matured COCs, respectively. The specific activities were significantly lower after IVM, for PFK (4.29 ± 0.48) 10^?3 and (0.94 ± 0.12) 10^?3, and for MDH (9.08 ± 0.93) 10^?3 and (1.89 ± 0.10) 10^?3 for immature and in vitro matured COCs, respectively. In vitro maturation percentages and enzymatic activity diminished with 20 mm 2‐oxoglutarate or 60 mm hydroxymalonate (p < 0.05). Viability was not affected by any concentration of the inhibitors evaluated. The U remained unchanged during IVM; however, the increase in the total protein content per COC provoked a decrease in the specific activity of both enzymes. Phosphofructokinase and MDH necessary for oocyte IVM would be already present in the immature oocyte. The presence of inhibitors of these enzymes impairs the meiotic maturation. Therefore, the participation of these enzymes in the energy metabolism of the porcine oocyte during IVM is confirmed in this study.     

The resistance of meat chickens vaccinated by aerosol with a live V4 Newcastle disease virus vaccine in the field to challenge with a velogenic Newcastle disease virus

Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days-of-age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination-inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non-HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia.     

The experimental production of big liver and spleen disease in broiler breeder hens

SUMMARY Big liver and spleen disease (BLS) was reproduced experimentally by intravenous (IV) and oral (PO) administration of BLS inocula to susceptible broiler breeder hens 34 to 36 weeks of age. Serological and pathological signs of BLS similar to those seen in the natural disease occurred in inoculated and in-contact birds. Splenomegaly was the earliest and often the only necropsy finding, with hepatomegaly and kidney enlargement occurring in some birds later in the course of the disease. After IV administration, serum antigen was detected between 2 and 4 weeks, and antibody between 3 and 5 weeks. After PO administration, antigen was detected between 2 and 4 weeks, and antibody between 3 and 6 weeks. Antibody persisted in all birds to the end of the experiment (6 weeks), and horizontal transmission probably occurred since in-contact birds developed BLS. Liver probably contained the highest concentration of BLS agent because it had the highest infectivity.