Assessment of Gastric Ulceration and Gastrin Response in Horses with History of Crib-Biting

It was hypothesized that horses exhibiting crib-biting (CB) have a greater degree of gastric mucosal damage and higher serum gastrin response to concentrate feeding than non-crib-biting (NCB) horses. Eighteen mature horses, 9 CB and 9 NCB, were used to determine prevalence and severity of gastric mucosal damage and effect of concentrate feeding on circulating gastrin. Horses were maintained on pasture with free access to hay and fed a pelleted concentrate diet twice daily. Number of crib-bites and duration of cribbing bouts were recorded in a 24-hour period. Endoscopic examinations (EE) of the squamous mucosa were performed and gastric fluid sampled after 24 to 28 hour feed removal. Following EE, horses were returned to pasture for 72 hours. Blood was collected following 12-hour feed removal (0 minutes), and at 60 and 120 minutes after consuming 1 kg of concentrate. Mean number of crib bites in 24 hours was 1,558 ± 303 with CB peaking prior to and during the afternoon feeding (3:30 PM, P < .05). There were no differences in the number or severity of ulcers, prevalence of hyperkeratosis, or baseline gastric pH between CB and NCB. Serum gastrin concentration at 60 and 120 minutes was greater (P < .05) and tended to be greater (P < .06), respectively, in CB than in NCB horses following feeding of concentrate. Crib-biting behavior in horses maintained on pasture was not associated with gastric mucosal damage; however, consumption of concentrate feed resulted in greater serum gastrin concentration in CB horses.     

Colloidal Centrifugation of Stallion Semen Results in a Reduced Rate of Sperm DNA Fragmentation

Stallion spermatozoa recovered and examined immediately after colloidal centrifugation resulted in a higher straight‐line velocity (VSL) than sperm processed using direct conventional centrifugation (p = 0.000), but there was no differences in the progressive motility or sperm DNA fragmentation (SDF) as determined by the sperm chromatin dispersion assay. However, when centrifuged spermatozoa were incubated at 37°C for 24 h to determine the rate of SDF (r‐SDF), a lower r‐SDF (p = 0.0011) was observed in those sperm recovered after colloidal separation (0.5 ± 0.1%/h) compared to direct (1.2 ± 0.4%/h) or no centrifugation (r‐SDF = 1.2 ± 0.3%/h). These results confirm that colloidal separation of stallion spermatozoa results in prolonged sperm DNA longevity, but these differences were only apparent following a period of incubation and dynamic assessment. Consequently, we strongly recommend the use of the dynamic form of the SDF assay for evaluating centrifugation and/or other ex vivo procedures, as a single basal assessment of SDF may inadvertently result in a false‐positive evaluation of DNA quality.     

Recombinant canine IL-13 receptor alpha2-Fc fusion protein inhibits canine allergen-specific-IgE production in vitro by peripheral blood mononuclear cells from allergic dogs

Human IL-13, like IL-4, is involved in the regulation of B-cell development, IgE synthesis and allergic responses. However, because IL-13 does not affect either murine Ig class switching or IgE production in vitro, the use of murine models to study the role of IL-13 in IgE-mediated diseases has been limited. In this communication, we report that recombinant protein of canine IL-13 (rcaIL-13) stimulates production of allergen-specific-IgE in vitro by peripheral blood mononuclear cells (PBMC) from flea allergen-sensitized dogs, and that this stimulation activity is specifically inhibited by recombinant protein of canine IL-13Ralpha2 and Fc fragment of canine IgG heavy chain (rcaIL-13Ralpha2-Fc). The data suggest that the regulatory effects of IL-13 on IgE production in canine PBMC are similar to those reported in humans. Thus, canine IL-13 may be a central mediator of allergic diseases in dogs, and allergic dogs may be excellent models for research on IgE-mediated diseases in humans.     

Hydrolysis of 1, 3-dichloropropene in dilute aqueous solution

Hydrolysis of [¹⁴C]-radiolabeled 1, 3-dichloropropene (1, 3-D) was studied at pH 5, 7 and 9 at 10, 20 and 30°C in sterile buffered water. The rate of hydrolysis was independent of pH at each temperature, with measured half-lives of 3-1 (±0.l), 11.3 (±0.5) and 51 (±2.3) days at 30, 20 and 10°C, respectively. The activation energy for the hydrolysis reaction was determined to be 23.9 kcal mol^?1 deg^?1. One hydrolysis product was formed during the course of the study and was identified by co-chrornatography with analytical standards, using h.p.l.c., to be 3-chloroallyl alcohol. The alcohol appeared to be stable to further hydrolytic conversion and was formed in the same cis: trans ratio as in the initial 1, 3-D starting material, indicating essentially identical rates of hydrolysis for the cis and trans isomers of 1, 3-D.     

Efficacy of selamectin against experimentally induced and naturally acquired infections of Toxocara cati and Ancylostoma tubaeforme in cats

The efficacy of selamectin against experimentally induced and naturally acquired infections of adult ascarids (Toxocara cati) and adult hookworms (Ancylostoma tubaeforme) was evaluated in five controlled studies in cats. Two studies evaluated the efficacy of selamectin against both ascarid (natural or induced) and hookworm (induced) infections; two studies evaluated the efficacy of selamectin against single natural infections of T. cati or A. tubaeforme; and the fifth study evaluated the efficacy of selamectin against induced infections of A. tubaeforme. Cats received selamectin topically in unit doses designed to deliver a minimum of 6mgkg(-1). Treatments were applied to the skin on each animal's back at the base of the neck in front of the scapulae. For experimentally induced infections, cats were inoculated orally with approximately 500 embryonated eggs of T. cati 56 days prior to treatment and/or approximately 150-250 larvae (L(3)) of A. tubaeforme 30 or 42 days prior to treatment. For both induced and naturally acquired infections, cats were allocated randomly to treatments (6-12 cats per treatment) on the basis of fecal egg counts to receive either selamectin or a vehicle containing the inert formulation ingredients. In all studies, adult worm counts were performed at necropsy 14 days after the last treatment administration. Against T. cati, a single application of selamectin provided a 100% reduction in the geometric mean number of adult worms for both experimentally induced and naturally acquired infections. Against A. tubaeforme, a single administration of selamectin provided a 99.4% reduction in the geometric mean number of adult worms in cats with natural infections, and an 84.7-99.7% reduction in adult worms in cats with induced infections.Two doses of selamectin administered at monthly intervals provided a 91.9% reduction in the geometric mean number of adult A. tubaeforme worms in cats with experimentally induced infections. The geometric mean numbers of adult worms (T. cati and A. tubaeforme) from selamectin-treated cats were significantly (P< or =0.0018) lower than for vehicle-treated cats in all studies. Thus, a single topical unit dosage providing a minimum dosage of 6mgkg(-1) selamectin was highly effective in the treatment of naturally acquired and experimentally induced infections of T. cati and A. tubaeforme in cats.     

Effect of Cryopreservation on the Sperm DNA Fragmentation Dynamics of the Bottlenose Dolphin (Tursiops truncatus)

Sperm DNA fragmentation is one of the major causes of infertility; the sperm chromatin dispersion test (SCDt) evaluates this parameter and offers the advantage of species‐specific validated protocol and ease of use under field conditions. The main purpose of this study was to evaluate sperm DNA fragmentation dynamics in both fresh and post‐thaw bottlenose dolphin sperm using the SCDt following different cryopreservation protocols to gain new information about the post‐thaw differential sperm DNA longevity in this species. Fresh and cryopreserved semen samples from five bottlenose dolphins were examined for sperm DNA fragmentation dynamics using the SCDt (Halomax^®). Sperm DNA fragmentation was assessed immediately at collection and following cryopreservation (T0) and then after 0.5, 1, 4, 8, 24, 48 and 72 h incubation at 37°C. Serially collected ejaculates from four dolphins were frozen using different cryopreservation protocols in a TES‐TRIS‐fructose buffer (TTF), an egg‐yolk‐free vegetable lipid LP1 buffer (LP1) and human sperm preservation medium (HSPM). Fresh ejaculated spermatozoa initially showed low levels of DNA fragmentation for up to 48 h. Lower Sperm DNA fragmentation (SDF) was found in the second fresh ejaculate compared to the first when more than one sample was collected on the same day (p < 0.05); this difference was not apparent in any other seminal characteristic. While there was no difference observed in SDF between fresh and frozen–thawed sperm using the different cryopreservation protocols immediately after thawing (T0), frozen–thawed spermatozoa incubated at 37°C showed an increase in the rate of SDF after 24 h. Sperm frozen in the LP1^? buffer had higher levels (p < 0.05) of DNA fragmentation after 24‐ and 48‐h incubation than those frozen in TTF or HSPM. No correlation was found between any seminal characteristic and DNA fragmentation in either fresh and/or frozen–thawed samples.     

Photo interpretive study of recovery of damaged lands near the metal smelters of Sudbury,Canada

Aerial photographs from 1970 and 1989 were used to assess the recovery of approximately 100000 ha of smelter-damaged lands near Sudbury, Canada. Recent improvements in air quality enabled conifers to recolonize about 22% of the semi-barrens, an area that consisted of a near monoculture of coppiced and stunted white birch (Betula papyrifera). The more heavily damaged barren areas, surrounding the three smelter sites, exhibited very little natural recovery during the study period. A municipal land reclamation program was responsible for most of the observed revegetation within the barren area. Between 1978 and 1988 approximately 2000 ha of barrens were reclaimed through soil treatment, grassing and tree planting. An estimated 7400 ha of the most heavily damaged land is still in need of immediate remedial treatment. Increased rates of natural recovery are expected in the future as SO₂ emissions are reduced. Continued municipal and expanded industrial reclamation programs in the 1990s will also greatly reduce the extent of bare land.     

Structure Activity Relationship of Brevenal Hydrazide Derivatives

Brevenal is a ladder frame polyether produced by the dinoflagellate Karenia brevis. This organism is also responsible for the production of the neurotoxic compounds known as brevetoxins. Ingestion or inhalation of the brevetoxins leads to adverse effects such as gastrointestinal maladies and bronchoconstriction. Brevenal shows antagonistic behavior to the brevetoxins and shows beneficial attributes when administered alone. For example, in an asthmatic sheep model, brevenal has been shown to increase tracheal mucosal velocity, an attribute which has led to its development as a potential treatment for Cystic Fibrosis. The mechanism of action of brevenal is poorly understood and the exact binding site has not been elucidated. In an attempt to further understand the mechanism of action of brevenal and potentially develop a second generation drug candidate, a series of brevenal derivatives were prepared through modification of the aldehyde moiety. These derivatives include aliphatic, aromatic and heteroaromatic hydrazide derivatives. The brevenal derivatives were tested using in vitro synaptosome binding assays to determine the ability of the compounds to displace brevetoxin and brevenal from their native receptors. A sheep inhalation model was used to determine if instillation of the brevenal derivatives resulted in bronchoconstriction. Only small modifications were tolerated, with larger moieties leading to loss of affinity for the brevenal receptor and bronchoconstriction in the sheep model.