Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: Gregory C. Troy x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To quantitatively evaluate expression of vascular endothelial growth factor (VEGF) in intracranial tumors in dogs and determine whether relationships exist between circulating and intratumoral VEGF concentrations and tumor type and grade.

Animals—27 dogs with primary intracranial neoplasms and 4 unaffected control dogs.

Procedures—Plasma and brain tumor samples were obtained from each dog, and plasma and intratumoral concentrations of VEGF were measured by use of an ELISA.

Results—Dogs with meningiomas (n = 11) were significantly older than dogs with oligodendrogliomas (7) or astrocytomas (9). Measurable VEGF was detected in all tumors, and a significant negative correlation between age and intratumoral VEGF concentration was detected. Age-adjusted comparisons identified significant differences in intratumoral VEGF concentrations among all tumor types; the highest VEGF concentrations were associated with astrocytomas. Within each tumor type, increasing tumor grade was significantly associated with increasing VEGF expression. Plasma VEGF concentrations were detectable in 9 of 27 dogs; the proportion of dogs with astrocytomas and a detectable circulating VEGF concentration (7/9 dogs) was significantly higher than the proportion of dogs with meningiomas (1/11 dogs) or oligodendrogliomas (1/7 dogs) with a detectable circulating VEGF concentration.

Conclusions and Clinical Relevance—Overexpression of VEGF appears common in canine astrocytomas, oligodendrogliomas, and meningiomas. In the neoplasms examined, intratumoral VEGF concentrations correlated well with tumor malignancy. The VEGF expression patterns paralleled those of analogous human tumors, providing evidence that dogs are a suitable species in which to study angiogenesis and intracranial neoplasia for human application.

Full access
in American Journal of Veterinary Research

Objective

To determine the correlation of seroimmunologic test results between reference and nonreference laboratories.

Design

Retrospective data analysis.

Procedure

Serum samples obtained from naturally infected dogs and cats were distributed to reference and nonreference laboratories for seroimmunologic testing. Correlation of test results was evaluated by use of nonparametric analysis.

Results

Correlation coefficients were high between laboratory groups for samples tested for feline immunodeficiency virus antibodies, FeLV antigen, and toxoplasmosis antibodies in cats. Results for feline immunodeficiency virus antibody tests from reference laboratories were more likely to be positive than results from nonreference laboratories. Test results for feline infectious peritonitis antibodies, antinuclear antibodies, and Borrelia antibodies in cats were not significant. Coefficient correlations were significant for results of heartworm antigen, Brucella antibodies, Toxoplasma antibodies, antinuclear antibodies, and rheumatoid factor in dogs. Results for Borrelia antibodies were not correlated between laboratory groups.

Clinical Implications

Results were highly correlated between reference and nonreference laboratories for 8 of 14 seroimmunologic tests. Seroimmunologic tests for use in cats were less correlated as a group than those for use in dogs. Poor correlation of results between laboratories was attributed to variations in control agents, antigens, reagents, technical expertise, and cutoff values and end-point titers used for diagnosis. (J Am Vet Med Assoc 1996,209:914-917)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of oral prednisone administration with or without ultralow-dose acetylsalicylic acid on coagulation parameters in healthy dogs and to assess intraindividual variation in thromboelastography results.

Animals—14 healthy research dogs and 10 healthy client-owned dogs.

Procedures—In a randomized controlled trial, research dogs underwent thromboelastography twice (3 days apart), and intraindividual variation in test results was calculated. Dogs were given prednisone (2 mg/kg/d, PO) plus acetylsalicylic acid (0.5 mg/kg/d, PO) or prednisone (2 mg/kg/d, PO) plus a placebo for 14 days, after which thromboelastography and other tests were repeated. Differences from preadministration (baseline) test results between and within groups were compared. In a separate trial, client-owned dogs also underwent thromboelastography twice 2 days apart to assess intraindividual variation in untreated dogs.

Results—Intraindividual variation in thromboelastography results for research dogs was ≤ 10% for maximum amplitude (MA) and α angle. In the research dogs, MA and fibrinogen values significantly increased from baseline, whereas percentage lysis 30 minutes after attainment of the MA as well as antithrombin activity significantly decreased within each group. In the dogs that received prednisone plus a placebo, percentage lysis 60 minutes after attainment of the MA was significantly lower than at baseline. For all parameters for research dogs, there was no difference between groups for change from baseline. Intraindividual variation in findings for client-owned dogs was similar to the variation for research dogs.

Conclusions and Clinical Relevance—Prednisone administration resulted in hypercoagulability in healthy dogs as indicated by an increase in MA and plasma fibrinogen concentration and a decrease in antithrombin activity. Concurrent ultralow-dose acetylsalicylic acid use had no effect on measured thromboelastography values. The high intraindividual variation in some thromboelastography parameters may preclude routine use of this technique in clinical practice.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether the prostaglandin E1 analogue, misoprostol, could preserve renal function in dogs receiving nephrotoxic doses of gentamicin.

Animals

12 (6/group) healthy sexually intact male dogs.

Procedure

All dogs were given high doses of gentamicin (10 mg/kg of body weight, IV, q 8 h, for 8 consecutive days). Six dogs (treatment group) received misoprostol (3 μg/kg, PO, q 8 h for the duration of the study) and 6 dogs (control group) received vehicle (1 capsule, PO, q 8 h). Renal function was assessed before treatment (day 0) and on days 3, 6, 9, and 11 after initiation of treatment by measurement of serum biochemical variables, urine specific gravity, and exogenous creatinine clearance. Serum electrolyte and protein concentrations and presence of proteinuria, glycosuria, and cylindruria were also determined. At the end of the study, renal histopathologic changes were evaluated.

Results

Dogs receiving misoprostol had significant reduction in exogenous creatinine clearance with time, compared with dogs receiving vehicle (P = 0.0264). Dogs receiving misoprostol tended to develop more severe azotemia, hyperphosphatemia, and renal histopathologic changes; however, results were not significantly different between groups.

Conclusion

Misoprostol (3 μg/kg, PO, q 8 h) did not preserve renal function and may have exacerbated gentamicin-induced nephrotoxicosis in this group of dogs.

Clinical Relevance

Supplementation of vasodilatory prostanoids may exacerbate renal dysfunction in dogs receiving high doses of gentamicin. (Am J Vet Res 1998;59:1048–1054)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate immunomodulatory properties of all-trans retinoic acid and a fully oxidized β-carotene dietary product in calves with Mannheimia haemolytica–induced pneumonia.

Animals—Twenty-five 6- to 10-week-old male Holstein calves for experimental inoculations and three 8- to 30-week-old Angus heifers for blood donations.

Procedures—In vitro, neutrophils and monocyte-derived macrophages isolated from blood of healthy Angus heifers were treated with all-trans retinoic acid (1μM) or fully oxidized β-carotene (8.3 μg/mL) for various times and assessed for markers of cellular death, antimicrobial function, and production of proinflammatory leukotriene B4. Following 28 days of dietary supplementation with fully oxidized β-carotene, Holstein calves were experimentally inoculated with M haemolytica. Bronchoalveolar lavage fluid was collected at 3 and 24 hours after challenge inoculation and analyzed for markers of apoptosis.

Results—In vitro, all-trans retinoic acid and fully oxidized β-carotene induced cell-selective, caspase-3–dependent apoptosis in neutrophils, which subsequently enhanced efferocytosis in macrophages. Conversely, neither treatment altered phorbol 12-myristate 13-acetate–induced oxidative burst, phagocytosis of nonopsonized zymosan (complement or antibody independent), or M haemolytica–induced leukotriene B4 production in bovine neutrophils. In vivo, fully oxidized β-carotene enhanced leukocyte apoptosis in bronchoalveolar lavage fluid as well as subsequent efferocytosis by macrophages without altering numbers of circulating leukocytes.

Conclusions and Clinical Relevance—Neutrophil apoptosis and subsequent efferocytosis by macrophages are key mechanisms in the resolution of inflammation. Findings for the present study indicated that all-trans retinoic acid and fully oxidized β-carotene could be novel nutraceutical strategies that may confer anti-inflammatory benefits for cattle with respiratory tract disease.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To investigate the anti-inflammatory and immunomodulatory properties of tulathromycin in vitro and in experimental models of Actinobacillus pleuropneumoniae–induced pleuropneumonia and zymosan-induced pulmonary inflammation in pigs.

ANIMALS Blood samples from six 8- to 30-week-old healthy male pigs for the in vitro experiment and sixty-five 3-week-old specific pathogen–free pigs.

PROCEDURES Neutrophils and monocyte-derived macrophages were isolated from blood samples. Isolated cells were exposed to tulathromycin (0.02 to 2.0 mg/mL) for various durations and assessed for markers of apoptosis and efferocytosis. For in vivo experiments, pigs were inoculated intratracheally with A pleuropneumoniae, zymosan, or PBS solution (control group) with or without tulathromycin pretreatment (2.5 mg/kg, IM). Bronchoalveolar lavage fluid was collected 3 and 24 hours after inoculation and analyzed for proinflammatory mediators, leukocyte apoptosis, and efferocytosis.

RESULTS In vitro, tulathromycin induced time- and concentration-dependent apoptosis in neutrophils, which enhanced their subsequent clearance by macrophages. In the lungs of both A pleuropneumoniae– and zymosan-challenged pigs, tulathromycin promoted leukocyte apoptosis and efferocytosis and inhibited proinflammatory leukotriene B4 production, with a concurrent reduction in leukocyte necrosis relative to that of control pigs. Tulathromycin also attenuated the degree of lung damage and lesion progression in A pleuropneumoniae–inoculated pigs.

CONCLUSIONS AND CLINICAL RELEVANCE Tulathromycin had immunomodulatory effects in leukocytes in vitro and anti-inflammatory effects in pigs in experimental models of A pleuropneumoniae infection and nonmicrobial-induced pulmonary inflammation. These data suggested that in addition to its antimicrobial properties, tulathromycin may dampen severe proinflammatory responses and drive resolution of inflammation in pigs with microbial pulmonary infections.

Full access
in American Journal of Veterinary Research