Bark necrosis of Acer pseudoplatanus L. in northern Britain

Severe bark necrosis in large Acer pseudoplatanus was studied at a site in northern England. Bark death occurred late in the growing season or in the dormant season on two occasions and was preceded by a notably dry summer in both cases. Of several fungi isolated from cankers and areas of recent bark necrosis, Nectria coccinea and Diplodina acerina were demonstrated to be capable of causing limited necrotic extension of physical wounds in healthy A. pseudoplatanus. A third sp., Phomopsis pustulata, though the most frequently isolated fungus, showed no such ability. It is proposed that summer drought in association with a variety of weakly pathogenic fungi can induce local bark necrosis in A. pseudoplatanus.     

Assessment of an enzyme-linked immunosorbent assay using a Taenia hydatigena fraction antigen in the diagnosis of cysticercosis in cattle.

Enzyme linked immunosorbent assay (ELISA) using a fraction of larval Taenia hydatigena cyst fluid antigen was carried out on 469 bovine sera collected at slaughter from feedlot cattle for the presence of anticysticercosis antibodies. Cysticerci, in low numbers, were found in the heart, tongue and/or masseter muscles of 84 of the 469 cattle at postmortem inspection. Only nine sera gave positive ELISA reactions and in only one of these nine animals were cysticerci found. Within the limitations of this study, the high rate of false negative and false positive reactions suggests that the ELISA with the antigen used is not a satisfactory procedure to diagnose cysticercosis in cattle, at least in animals with light infections.     

Breed effects and heterosis in advanced generations of composite populations for growth traits in both sexes of beef cattle

Heterosis effects for birth weight, ADG from birth to weaning, 200-d weight, ADG from weaning to 368 d, 368-d weight, 368-d height, 368-d condition score, and 368-d muscling score (males only) were evaluated separately for each sex in F1, F2, and combined F3 and F4 generations in three composite beef cattle populations. Breed effects were evaluated for the nine parental breeds (i.e., Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C]) that contributed to the three composite populations (MARC I = 1/4 C, 1/4 B, 1/4 L, 1/8 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, 1/4 A). Breed effects were significant for all traits evaluated. The large differences among breeds for growth and size traits in combined additive direct and additive maternal genetic effects (Gi + Gm) provide an opportunity to use genetic differences among breeds to achieve and maintain optimum additive genetic (breed) composition for growth and size traits to match cattle genetic resources to a wide range of production and marketing situations. Combined individual and maternal heterosis was significant in the F1, F2, and combined F3 and F4 generations for each composite population and for the mean of the three composite populations in both sexes for most of the traits evaluated. In both sexes, heterosis retained in combined F3 and F4 generations was greater (P less than .05) than expected based on retained heterozygosity for birth weight, ADG from weaning to 368 d, and for 368-d weight and did not differ (P greater than .05) from expectation for other traits. These results support the hypothesis that heterosis in cattle for traits related to growth and size is due to dominance effects of genes.     

Growth of Rhododendron,Rudbeckia and Thujia and the Leaching of Nitrates as Affected by the pH of Potting Media Amended with Biosolids Compost

A conventional potting media containing peat moss, softwood bark and sand was amended to contain 0,25,50,75 and 100 (percent vol^?1) municipal compost made from yard waste and biosolids. Each medium was adjusted with limestone and sulfur to an approximate pH of 5.0, 6.0 or 7.0. Rhododendron Panticum L. ‘Anah Kruschke’ (Rhododendron), Thujia occidentalis L. (Arborvitae) and Rudbeckia hirta L. ‘Goldilocks’ (Black-eyed Susan) were grown in each medium and pH level for 18 months. Leachate from pots was tested for NO₃-N and NH₃-N+NH₄-N to determine how media pH and the amount of compost effected the potential for potting media to be a source of nitrate in surface and ground water.

Media pH affected plant growth more than the percent compost. Compared to media with a pH of 7.0, statistically significant increases in the growth of Rhododendron occurred in media with a pH of 5.0 or 6.0. This pH effect was similar but less pronounced for Thujia. Growth of Rudbeckia was not effected by media pH or percent compost. Media with 0 and 25 percent compost leached the least nitrogen regardless of pH. Media with 75 and 100 percent compost at pH 5.0 and 6.0 leached the most nitrogen. The increase in nitrogen leaching in the more acidic media was associated with higher concentrations NH₃-N+NH₄-N. Nitrogen in leachate was greatest during the four weeks immediately after the pots were placed in the field and four weeks after fertilizer was applied in June of the second year of the experiment.     

Variation in modulus of elasticity (E) along Acer platanoides L. (Aceraceae) branches

Arborists and managers of amenity trees could benefit from an improved understanding of how tree canopies withstand loading events such as wind, snow or ice. Knowledge of how material properties change along tree branches is important in understanding how a branch tips can bend in the wind yet resist displacement at the base which could lead to branch failure. Limited knowledge of modulus of elasticity (E or stiffness) in branch wood is available in the literature and is typically measured at only one location on a branch. This study investigated variation of E and density-specific E (E/ρ) at five locations along the axis of 20 branches from seven trees. E and E/ρ were found to be 70% lower at the branch tips than in the proximal locations. The variation in E was negatively correlated with the percentage of tissue area composed of vessels and positively correlated with mean fiber cell wall size, suggesting a balance between the two principle functions of hydraulics and mechanics. Reaction wood was observed in the form of gelatinous layers in fibers along the branch tops, but did not result in a difference in E between the top and bottoms at each branch location. It is proposed that differences in material properties are probably related to wood development type, as juvenile wood is considered to have lower stiffness than mature wood.     

Evaluation of the effects of dietary n-3 fatty acid supplementation on the pharmacokinetics of doxorubicin in dogs with lymphoma

OBJECTIVE: To determine the effect of dietary n-3 fatty acids on the pharmacokinetics of doxorubicin in dogs with lymphoma. ANIMALS: 23 dogs with lymphoma in stages IIIa, IVa, and Va. PROCEDURE: Dogs receiving doxorubicin chemotherapy were randomly allocated to receive food with a high (test group) or low (control group) content of n-3 fatty acids. Serum doxorubicin and doxorubicinol concentrations were measured via high-performance liquid chromatography before and 6 to 9 weeks after initiation of the diets. Lymph node concentrations of doxorubicin were assessed 6 hours after the initial treatment. Dogs' body composition was assessed by means of dual-energy x-ray absorptiometry scans. RESULTS: No significant differences in doxorubicin pharmacokinetics were detected between treatment groups. Significant differences existed between the first and second sampling times among all dogs for area under the curve, maximum serum concentration, and clearance. Differences in body composition did not affect measured pharmacokinetic variables. The terminal elimination half-life was longer in dogs in which a long-term remission was achieved than in dogs that did not have remission. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary supplementation of n-3 fatty acids is common in veterinary patients with neoplasia, but supplementation did not affect doxorubicin pharmacokinetics in this population of dogs. Explanations for the beneficial effects of n-3 fatty acids other than alterations in the pharmacokinetics of chemotherapy drugs should be investigated. Dogs may metabolize drugs differently prior to remission of lymphoma than when in remission. The pharmacokinetics of doxorubicin at the time of the first administration may predict response to treatment.     

Temporal detection of equine herpesvirus infections of a cohort of mares and their foals

The objectives of this study were to estimate the prevalence of equine herpesviruses (EHV) 1-5 in the nasal secretions (NS) of a cohort of 12 mares and their foals from birth to 6 months of age, estimate the prevalence of EHV-1-5 infection of peripheral blood mononuclear cells (PBMC) of selected foals, and investigate phylogenetic relationships amongst the various strains of EHV-2 and 5. Virus-specific PCR assays were used to detect EHV-1-5 in NS and PBMC. A homologous portion of the glycoprotein B (gB) gene of the various strains of EHV-2 and 5 was sequenced and compared. EHV-2, 4, and 5 were all detected in NS from the horses, but only EHV-4 was associated with respiratory disease (P=0.005). EHV-2 and 5 infections were both common, but foals shed EHV-2 in their NS earlier in life than EHV-5 (P=0.01). Latent EHV-2 and 5 infections were detected in the PBMC of 75 and 88%, respectively, of the foals at approximately 6 months of age. The strains of EHV-2 shed in the NS of individual horses were more genetically heterogeneous than the strains of EHV-5 (95.5-99.3% versus 98.8-99.3% nucleotide identity, respectively). One-month-old foals typically shed strains of EHV-2 that were identical to those infecting their dams whereas older foals often shed virus strains that were different from those of their dams. Although herpesvirus infections were ubiquitous in this cohort of horses, there were distinct clinical consequences and clear epidemiological differences between infections with the different viruses.     

Biological and molecular characterization of a canine hemangiosarcoma-derived cell line

Canine hemangiosarcoma (HSA) is a devastating disease. Investigation of novel therapies has been limited by the limited availability of canine HSA-derived cell lines. We report the development of a canine HSA-derived cell line, DEN-HSA, which recapitulates features of angiogenic endothelium. DEN-HSA cells were derived from a spontaneous HSA arising in the kidney of a dog. DEN-HSA displayed surface molecules distinctive of endothelial histogenesis, including factor VIII-related antigen, ICAM-1 and alpha(v)beta3 integrin. In vitro, DEN-HSA formed microvascular tube-like structures on Matrigel, and proliferated in response to a variety of angiogenic growth factors. The cells expressed mRNA and protein specific for bFGF and its receptors, and VEGF and its receptors, among others. DEN-HSA conditioned medium evoked a marked angiogenic response in a murine corneal pocket assay, indicating potent proangiogenic activity of substances secreted by this cell line. This research confirms the DEN-HSA cell line as endothelial in origin, suggests the presence of angiogenic growth factor autocrine loops, and offers the potential to utilize DEN-HSA cells for the study of novel therapies that modulate endothelial proliferation.     

Investigation of a novel, heritable bleeding diathesis of Thoroughbred horses and development of a screening assay

BACKGROUND: Bleeding in racing horses associated with exercise appears to be multifactorial, and clinical investigation into severe cases rarely occurs. Previously, we reported a severe bleeding diathesis in a Thoroughbred mare. Herein, we describe the cellular physiology of this defect, provide a diagnostic tool for identifying it, and demonstrate that the dysfunction is heritable. HYPOTHESIS: The subject has a heritable defect in platelet secretion that reduces thrombin generation in the absence of additional plasma factors and delays the onset of thrombin production even in the presence of these factors. ANIMALS: The study included 3 clinically normal Thoroughbred horses: the subject and her offspring. METHODS: Washed platelets were examined for their ability to (1) translocate phosphatidylserine to the outer leaflet of the platelet membrane as determined by annexin-V binding, (2) generate thrombin as assessed by the activity of the prothrombinase enzyme complex, and (3) bind fibrinogen and form aggregates as determined by flow cytometry. RESULTS: Subject and offspring platelets created procoagulant surfaces by translocating phosphatidylserine. The subject's platelets demonstrated reduced prothrombinase activity, resulting in decreased production of thrombin relative to control platelets. Subject and offspring platelets bound less fibrinogen than control platelets when stimulated with thrombin. CONCLUSIONS AND CLINICAL IMPORTANCE: The subject mare has a transmissible defect that involves reduced generation of thrombin by activated platelets, resulting in decreased aggregation and ineffective clotting. A flow cytometric assay of fibrinogen binding to washed platelets discriminates individuals with this platelet dysfunction and may be useful for discerning subclinical congenital or acquired platelet dysfunctions.