A polygon-based spatial (PBS) model for simulating landscape change

A spatial model of long term habitat succession at a degrading Louisiana wetland was constructed based upon simulating exchanges across irregularly shaped polygons. Polygons represented the natural morphology which is indicative of the natural landscape. The PBS model was partially successful in simulating spatial habitat changes over a 28-year period when more than 1000 ha of wetland loss occurred (r²=.56). General landscape trends did, however, emerge from the model development. Areas of high annual water level fluctuations, and high primary productivity were less likely to change from wetlands to open water and were most likely to recover if altered. We discuss the potential for predictive improvement and for integration with polygon-based geographic information systems, and conclude that a PBS model demonstrates the need for spatially explicit landscape management.     

The influence of post-exposure temperature on the toxicity of insecticides to Ostrinia nubilalis (Lepidoptera: Crambidae)

The influence of post-treatment temperature on the toxicities of two pyrethroids (lambda-cyhalothrin and bifenthrin), a carbamate (methomyl) and a spinosyn (spinosad) to Ostrinia nubilalis (Hubner) larvae was evaluated in laboratory assays. From 24 to 35 degrees C, the toxicities of the pyrethroids decreased 9.5- and 13.6-fold while spinosad toxicity decreased 3.8-fold. The toxicity of methomyl did not change significantly. The results demonstrate that the most effective insecticide against a pest may vary with environmental conditions. In situations where comparable products from multiple insecticide classes are available, temperature should be included as a factor in the decision-making process.     

A peptide vaccine administered transcutaneously together with cholera toxin elicits potent neutralising anti-FMDV antibody responses

In this study a synthetic peptide representing residues 141-159 from the GH loop of VP1 protein of foot-and-mouth disease virus was tested for its capacity to elicit virus neutralising antibodies in mice after transcutaneous immunisation. Topical application of the peptide conjugated to bovine serum albumin together with cholera toxin as an adjuvant elicited anti-peptide antibody responses with strong virus neutralising activity. The combination of cholera toxin with an immunostimulatory CpG motif resulted in the induction of IgG1 and IgG2a anti-peptide antibodies with significantly enhanced virus neutralising activity. To shed more light on the mechanisms of cholera toxin adjuvanticity we demonstrated its binding to keratinocytes via GM(1)-gangliosides. This was followed by an increase of the intracellular cAMP and the rapid diffusion of cholera toxin throughout the epidermis. These findings demonstrate that peptide-based vaccines when combined with the appropriate adjuvant(s) can elicit potent virus neutralising antibody responses after transcutaneous immunisation. However, experiments in target species will be required to confirm the potential of this simple vaccination procedure in livestock.     

Solid-state light sources getting smart

More than a century after the introduction of incandescent lighting and half a century after the introduction of fluorescent lighting, solid-state light sources are revolutionizing an increasing number of applications. Whereas the efficiency of conventional incandescent and fluorescent lights is limited by fundamental factors that cannot be overcome, the efficiency of solid-state sources is limited only by human creativity and imagination. The high efficiency of solid-state sources already provides energy savings and environmental benefits in a number of applications. However, solid-state sources also offer controllability of their spectral power distribution, spatial distribution, color temperature, temporal modulation, and polarization properties. Such "smart" light sources can adjust to specific environments and requirements, a property that could result in tremendous benefits in lighting, automobiles, transportation, communication, imaging, agriculture, and medicine.     

Efficacy of tulathromycin injectable solution for the treatment of naturally occurring Swine respiratory disease

Tulathromycin, a novel triamilide antimicrobial, was evaluated for treatment of swine respiratory disease (SRD) in field efficacy studies involving 720 pigs in six North American swine herds. In each study, feeder pigs with clinical SRD were randomly assigned in equal numbers to a group treated with tulathromycin given as a single injection at 2.5 mg/kg of body weight or to a saline-treated control group. Four of the studies included a third group treated with ceftiofur sodium for 3 consecutive days at 3 mg/kg of body weight. Pigs were treated on day 0 and evaluated for treatment response on day 7. In each study, 10 or more nontreated pigs and saline-treated pigs that did not respond to treatment underwent necropsies to obtain lung samples that were evaluated for SRD pathogens. The overall cure rate was 46.4% for saline-treated pigs, 71.1% for tulathromycin-treated pigs, and 63.1% for ceftiofur-treated pigs. The cure rate for tulathromycin-treated pigs was significantly higher than for saline-treated pigs (P = .0116). Mortality from SRD occurred in 24 control pigs, seven tulathromycin-treated pigs, and one ceftiofur-treated pig. The mortality rate was significantly lower for both the tulathromycin- and ceftiofur-treated pigs compared with those treated with saline (P = .0148 and P = .0195, respectively). Actinobacillus pleuropneumoniae, Pasteurella multocida, Haemophilus parasuis, and Mycoplasma hyopneumoniae, bacteria commonly associated with SRD, were isolated from SRD-affected pigs. Under field conditions, tulathromycin injectable solution given as a single IM dose of 2.5 mg/kg of body weight was safe and effective in the treatment of SRD.     

Effect of topical application of diclofenac liposomal suspension on experimentally induced subcutaneous inflammation in horses

OBJECTIVE: To determine whether 1% diclofenac liposomal suspension (DLS) ointment would be absorbed transdermally and attenuate experimentally induced subcutaneous inflammation in horses. ANIMALS: 7 healthy adult horses. PROCEDURE: Inflammation was produced by injecting 1% sterile carrageenan into subcutaneously implanted tissue cages 8 hours before (time -8) and at the time of application of test ointment. A crossover design was used. Horses received 1 of 2 treatments (topically administered control or DLS ointments) during 48 hours of carrageenan-induced subcutaneous inflammation. A single application of test ointment (7.2 g) was applied over each tissue cage (time 0). Samples of transudate and blood were collected at -8, 0, 6, 12, 18, 24, 30, 36, and 48 hours. Plasma and transudate diclofenac concentrations were determined by use of high-performance liquid chromatography. Transudate concentrations of prostaglandin E2 (PGE2) were determined with a competitive enzyme immunoassay. RESULTS: DLS was absorbed transdermally. The highest concentration (mean +/- SEM, 76.2 +/- 29 ng/mL) was detectable in tissue-cage fluid within 18 hours after application. Minimal concentrations of diclofenac were detectable in plasma. Application of DLS significantly decreased transudate concentrations of PGE2 at 6 and 30 hours. Decreases in PGE2 concentration were observed in the DLS group at all collection times. CONCLUSIONS AND CLINICAL RELEVANCE: A single topical application of DLS resulted in concentrations of diclofenac in transudate within 6 hours and significantly attenuated carrageenan-induced local production of PGE2. Results of this study suggest that DLS is readily absorbed transdermally and may be efficacious for reducing subcutaneous inflammation in horses.     

Urine volume estimations in dogs recovering from intervertebral disc prolapse surgery

Ultrasonographic estimations of residual bladder urine volume (expressed as a percentage of the estimated bladder volume before micturition--the "percentage residual urine") and calculations of the amount of urine voided were performed in 15 dogs before and up to 25 days after surgery for thoracolumbar disc prolapse. The percentage residual urine was influenced by the grade of disc prolapse (F = 9.223; p < 0.01). Over the first four days after surgery, there was a significant change in percentage residual urine (F = 3.995; p < 0.05) and an increase in the calculated amount of urine voided (F = 12.305; p < 0.01). It is suggested that ultrasonographic estimation of percentage residual urine may be valuable in monitoring the progress of dogs undergoing treatment for thoracolumbar disc disease.     

Seasonal availability of gastrointestinal nematode larvae to cattle on pasture in the central highlands of Kenya

The type and level of infective strongylid nematode larvae on pasture were monitored fortnightly from July 1995 to June 1996 in the central highlands of Kenya. The number of larvae on pasture was moderate, reaching > 1,200 kg(-1) dry matter of grass during the period of, and soon after, the rains, and remained low in the dry seasons. The number of larvae on pasture was directly related to the rain-fall pattern which was found to be the most important factor for the development of eggs and free-living stages. Haemonchus was the predominant genus, followed in decreasing order by Trichostrongylus, Cooperia, Oesophagostomum and Bunostomum. The mean total adult worm burdens of tracer calves released at monthly intervals were related to the levels of herbage larvae and there was a positive correlation between faecal worm egg counts and worm burdens (r = 0.58) during the study period. These results indicate that a reduction in the contamination of pasture with nematode eggs before the rains could result in pastures carrying fewer larvae and thus form the basis of effective worm control programmes for cattle.