The effect of selenium deficiency on the feed consumption and growth of goats

The feed consumption of goats was only reduced after considerable Se depletion. The conversion of Se-depleted animals to an Se-rich ration increased feed consumption within one day. An intrauterine Se deficiency (less than 38 micrograms Se/kg DM of the ration) did not induce intrauterine growth depression in kids. Se depletion led to a highly significant postnatal growth depression which increased with advancing Se depletion both during the lactation period and after weaning.     

Western blot analyses and LD50 determinations of Toxoplasma gondii isolates

Western blot analysis of tachyzoite detergent extracts revealed striking similarities and only minor differences in the antigenic profiles of four isolates, including one new isolate of Toxoplasma gondii. At least nine common protein bands with molecular weights ranging from 14,000-108,000 were recognized by all antitoxoplasma antisera. Differences existed primarily between molecular weights 28,000 and 33,000. The LD50 determinations showed that strains of laboratory mice were affected differently by the various Toxoplasma isolates used in this study. Results indicate a need for further investigations into whether there are true strain differences of Toxoplasma gondii or simply different isolates of the same strain of this single species in the genus Toxoplasma.     

Behavior of palatine tissue during abnormal palatogenesis in the mouse (Mus musculus)

The development of the palatine process in die presence of phenylbutazone and indomethacin was carried out in preparations collected at 13.5 days of gestation, followed by tissue culture in the mouse. It was demonstrated that both agents interfere with the normal development of the palate. The mechanisms which are apparently responsible for this abnormality are discussed.     

Limitations of in situ hybridization for the detection of bluetongue virus in blood mononuclear cells

In situ nucleic acid hybridization was tested for the ability to detect bluetongue virus (BTV) nucleic acids in blood mononuclear cells. A standard protocol was devised and applied to the demonstration of BTV genetic sequences in cultured bovine mononuclear cells that had been infected in vitro. In situ hybridization using biotinylated single-stranded RNA probes, in the presence of 50% formamide at 50 C, demonstrated an intense, positive signal in 0.001-0.01% of the BTV-infected cultured mononuclear cells. The protocol was applied to isolated mononuclear cells from an experimentally infected heifer. No infected cells were observed by this method, although the blood specimens were obtained during peak viremia.     

Survey of herbicide residues in soil and wells in three citrus orchards in Valencia, Spain

Soil samples taken in summer 1989 and winter 1990 at different depths from three citrus orchards of the Valencia region (Spain) with a long history of residual herbicide treatments were analysed with bioassays and chromatographic procedures. The herbicides involved were atrazine, bromacil, diuron, simazine, terbuthylazine, terbumetone, terbutryn and trifluralin. Water samples from wells in the orchards were also analysed. The concentrations of the herbicides were very low, often below the limit of determination, and were always highest in the upper layers of soil. After a very unusual period of heavy rain, small quantities of some chemicals were found in the well water. The conclusion was that in these orchards the herbicides applied at currently used rates are unlikely to accumulate in any layers of the soil.     

Cytochrome P-450 Inducers and Inhibitors Interfering with Ecdysone 20-Monooxygenases and Their Activities during Postembryonic Development of Neobellieria bullata Parker

The cytochrome P-450-dependent microsomal and mitochondrial ecdysone 20-monooxygenase systems convert ecdysone into 20-hydroxyecdysone. The microsomal fraction of fat bodies of zero h wandering stage fleshfly larvae (Neobellieria bullata; Diptera: Sarcophagidae) has a high ecdysone 20- monooxygenase activity. The effects of cytochrome P-450 inhibitors were investigated in vitro on microsomal ecdysone 20-monooxygenase. Metyrapone, fenarimol and certain imidazole derivatives (KK-42, KK-110, KK-135 and PIM) are strong inhibitors. The IC₅₀ value of KK-110, which is the strongest inhibitor, is 2 × 10^?7 M. A triazolyl and two cyclopropylamine derivatives have low activity. The activities of different NADPH-cytochrome c (P-450) reductase inhibitors were also assessed; diquat dibromide is a moderate inhibitor of microsomal ecdysone 20-monooxygenase, while paraquat dichloride has no activity. In-vivo experiments with cytochrome P-450 inducers and inhibitors gave the following results: (a) fenarimol, FI-121, precocene-2 caused “permanent” first-instar larvae; (b) barbital, phenobarbital and their sodium salts caused significant delay in larval development; (c) PIM, PTM, metyrapone, KK-42, KK-135, J-2710, RH 5849 and colchicine caused moulting disturbances; (d) J-2710, PIM, PTM, KK-42, KK-135, RH 5849 and colchicine caused lethal spiracle and mandible malformation; (e) KK-110, fenarimol, barbital and phenobarbital caused precocious pupariation.     

In vitro efficacy of N-duopropenide, a recently developed disinfectant containing quaternary ammonium compounds, against selected gram-positive and gram-negative organisms

OBJECTIVE: To study the efficacy of N-duopropenide against various gram-positive and gram-negative organisms. SAMPLE POPULATION: One field strain each of Pasteurella multocida subsp multocida, Staphylococcus aureus, Listeria monocytogenes, and L ivanovii, and 2 field strains of Escherichia coli. PROCEDURE: Strains were tested with and without serum as organic matter, using quantitative suspension and carrier tests. Six concentrations of active ingredient (0.005, 0.01, 0.05, 0.11, 0.27, and 0.55%) and 6 contact times (15 and 30 seconds and 1, 3, 5, and 10 minutes) were studied for each. RESULTS: Globally, N-duopropenide was more effective in suspension tests than in carrier tests, and when organisms were suspended in saline solution rather than serum. Under the most disadvantageous conditions (carrier test with serum), a concentration of 0.55% N-duopropenide acting for only 15 seconds was effective in inactivating P multocida subsp multocida and was even more effective against the 2 Listeria species tested. For E coli strains, the same concentration also was effective, but after 10 minutes of contact. On the other hand, N-duopropenide was unable to inactivate the S aureus strain in the carrier test with serum, a concentration of 0.55% for 10 minutes was necessary to inactivate it without organic matter; however, N-duopropenide was highly effective against this organism in the suspension test, even with serum. CONCLUSION: N-duopropenide was highly effective in vitro against 5 of the most commonly encountered organisms in clinical veterinary medicine and, consequently, might be a good choice in control measures against common pathogenic organisms in modern production systems.     

Modelling the spread of a viral infection in equine populations managed in Thoroughbred racehorse training yards

A Monte Carlo model that simulates the management life cycle of a horse population in training on a Thoroughbred flat racing yard (i.e. stable) was developed for computer implementation. Each horse was characterised by several state variables. Discrete events at the horse level were triggered stochastically to reflect uncertainty about some input assumptions and heterogeneity of the horse population in a particular yard. This mathematical model was subsequently used to mimic the spread of equine influenza (EI) within a typical yard following the introduction of one or several infectious horses. Different scenarios were simulated to demonstrate the value of strategies for preventing outbreaks of EI. Under typical UK management conditions and vaccination protocols, the model showed that EI would propagate and that the timing of vaccination in connection with the racing season and the arrival of new horses was a critical factor. The predicted outcomes (based on published characteristics of one EI vaccine) suggested that vaccination in mid-December with boosters in June and September was a viable and successful strategy in preventing the spread of EI in a training establishment.