In vitro markers to differentiate an avirulent from a virulent strain of aujeszky's disease virus

The susceptibility of the virulent NIA-2 and avirulent Bartha strains of Aujeszky's disease virus to various physical and chemical methods of inactivation was investigated. Both strains were highly sensitive to UV radiation and to various combinations of trypsin concentration and temperature. The Bartha strain was the more thermostable and pH-sensitive.     

Ulceration in the proximal portion of the urethra as a cause of hematuria in horses: four cases (1978-1985)

Sudden onset of hematuria was associated with mucosal ulceration of the proximal portion of the urethra in 1 stallion and 3 geldings. Hematuria was observed characteristically and consistently at the end of urination. Mucosal ulceration was identified endoscopically in the proximal portion of the urethra at the level of the ischial arch. Biopsy of an ulcerated area of the proximal urethra in one gelding revealed transitional cell carcinoma. Treatment regimens varied from systemic antimicrobial and/or vasoactive therapy to diversion of urinary flow via a temporary perineal urethrostomy. Hematuria resolved in 14 to 24 days (average, 20 days) after treatment was begun, except in one gelding that died of undetermined causes during an initial examination. In the 3 remaining horses, hematuria had not recurred for up to 9 years (average, 1 year).     

Development of a computerized systems model for health management decision support in growing hogs

A study was designed to provide decision support for health management in growing hogs. A dynamic, stochastic systems model for a confinement, continuous production hog growing enterprise (including nursery, grower and finisher phases) was developed to simulate the economic effects of disease, available floor space and feed additives using farm- specific data. Modeling techniques included: discrete and distributed (continuous) delays; triangular probability density functions; autocorrelation; table look-up functions; an alpha-beta tracker; non-linear, constrained optimization. The model was designed to be initialized with the system's current status, using an accompanying production/financial database to achieve individual-farm specificity. Initialization of rate variables required ‘reverse optimization’ of historical system performance. Model predictions are based on an adjustment approach, where changes in current performance are dictated by changes in disease rates, available floor space and feed additive use. These effects vary randomly, but are autocorrelated between production phases, between similar diseases and over time.     

Fenvalerate residues in milk following topical treatments to dairy cows

Two mature Holstein cows were treated with 0.1g of fenvalerate each, in six consecutive topical treatments at intervals of 3 or 4 days. Neither of the diastereoisomers of fenvalerate was detected in the milk 6h after the application. After 3 days, the mean fenvalerate residue was 0.46μg litre⁻¹; by day 4, this residue had declined below the detection limit of 0.1μg litre⁻¹ for each of the diastereoisomers. Two Holstein cows were also treated with 0.5g of fenvalerate per cow in three consecutive topical treatments at intervals of 14 days. Residues in whole milk were at a maximum 6h after treatment and declined to less than 0.2μg litre⁻¹ over 21 days. Only 0.03 to 0.06% of the applied fenvalerate appeared in the milk as the intact insecticide.     

A method for assessing the relative importance of seabird breeding colonies

Evaluating the importance of seabird breeding colonies in a national or international context is an essential part of conservation planning. A method for assesiing seabird sites, and for selecting a series of key colonies, is described, following Ratcliffe's (1977) guidelines. The present study uses seabirds in the Republic of Ireland and data recently collected for a breeding seabird inventory. The method is suitable for use on seabird populations elsewhere. The inventory listed over 400 sites, of which 133 were identified by this study to be of national importance to conservation. Among these were 11 internationally important colonies. Thirty-one of the colonies were selected as key sites of special importance.     

Confirmation of reduced toxicity of deoxynivalenol in extrusion-processed corn grits by the MTT bioassay

The objective of this study was to determine the loss of toxicity of deoxynivalenol in extruded cereal-based products by the tetrazolium salt (MTT) bioassay using a sensitive Chinese hamster ovary (CHO-K1) cell line and to compare the results to chemical (high-performance liquid chromatography, HPLC) and biochemical (enzyme-linked immunosorbant assay, ELISA) methods of analysis. A split-split plot design was used for the extrusion process experiments at temperatures of 150, 175, and 200 degrees C and screw speeds of 70 and 140 rpm. The initial mean deoxynivalenol concentration in the corn grits artificially contaminated with Fusarium graminearum was found to be 23.5 mug/g as measured by HPLC. The percent reductions of deoxynivalenol in the contaminated corn grits upon extrusion processing ranged from 22 to 35%, from 21 to 34%, and from 21 to 37% as measured by HPLC, ELISA, and MTT bioassay, respectively. The MTT bioassay results were more closely correlated with HPLC (r = 0.90) results than with ELISA results (r = 0.78). The MTT bioassay, using a sensitive mammalian cell line, was demonstrated to be a useful method for quantification of deoxynivalenol as well as a potential toxicity screening method for contaminated extruded cereal-based products.     

Efficient and sensitive method for quantitative analysis of alkaloids in hardinggrass (Phalaris aquatica L.)

An efficient high-performance thin-layer chromatography (HPTLC) method for the analysis of alkaloids in hardinggrass (Phalaris aquatica L.) was developed. The method employed HPTLC glass plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of ethyl acetate/chloroform/7 N NH4OH in methanol (8:2:1, v/v/v). Using unidimensional double-development, bands were well separated for 10 alkaloid standards as well as alkaloids observed in hardinggrass plant extracts. Identities of compounds observed using HPTLC were validated by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Software was used to quantify individual alkaloids in plant samples based on HPTLC retention factors and intensities relative to standards of known concentration. Correlation coefficients of 0.99 were obtained between estimated and actual concentrations for four standards (methyltyramine, hordenine, gramine, and 5-methoxydimethyltryptamine), with linearity in the range of 120-3840 ng/spot. The HPTLC method is repeatable and specific for beta-carboline, tryptamine, gramine, and tyramine type alkaloids in mixed standard and plant extracts. Initial results indicate substantial variation in alkaloid composition among and within hardinggrass populations.