Browsing by Author "Troy, Gregory C."
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- Characterization of Canine Leishmaniasis in the United States: Pathogenesis, Immunological Responses, and Transmission of an American Isolate of Leishmania infantumRosypal, Alexa C. (Virginia Tech, 2005-04-06)Leishmania infantum, an etiologic agent of zoonotic visceral leishmaniasis, has recently emerged in the foxhound population in the United States and parts of Canada. Leishmania infections are usually spread to mammals by infected sand flies, however epidemiological data do not support a role for sand fly transmission in North America. The purpose of this work was to isolate and characterize L. infantum from a naturally infected foxhound from Virginia (LIVT-1 isolate). A mouse model of North American leishmaniasis was developed using immunocompetent and genetically immunodeficient mouse strains infected with LIVT-1 promastigotes by different inoculation routes. The intravenous route of infection was superior to the subcutaneous route for inducing consistent experimental infections and mice lacking interferon gamma, inducible nitric oxide synthase, or B-cells were resistant to clinical disease. Experimental infections in dogs were performed to examine the infectivity, immune responses, and pathogenicity of LIVT-1. Experimentally infected dogs developed parasitologically proven infections and a range of clinical manifestations that were similar to those observed in naturally occurring disease. Diagnostic tests including culture and cytologic evaluation of bone marrow and lymph node aspirates, polymerase chain reaction, and serology by indirect fluorescent antibody test, and recombinant K39 (rK39) immunoassay were evaluated. Kappa statistics revealed that PCR had the highest level of agreement with culture and cytology results although the rK39 dipstick assay consistently identified more experimentally infected dogs. Flow cytometry revealed no significant differences (p>0.05) in CD4+ or CD8+ expression on peripheral blood lymphocytes. Alternate transmission mechanisms in experimentally inoculated mice and dogs were investigated. PCR revealed a low level of vertical and direct transmission of LIVT-1 in inoculated BALB/c mice. Leishmania DNA was detectable by PCR in tissues from puppies from a LIVT-1 infected beagle. Although the strain of L. infantum infecting foxhounds in North America appears to predominantly use a non-vector transmission mode, the disease it produces is similar to canine leishmaniasis in other parts of the world. Non-sand fly transmission may be responsible for maintaining infections in the foxhound population. Results from this work will lead to improvement in diagnosis, clinical management, and control of canine leishmaniasis in North America.
- Comparison of two saline loading protocols for preventing nephrotoxicosis associated with high-dose cisplatinFallin, Edward Alton (Virginia Tech, 1994-09-30)Cisplatin is an antineoplastic drug used to treat malignant tumors in human beings and dogs. Nephrotoxicosis was initially considered dose limiting. The use of saline loading and hypertonic saline administration protocols allowed dose escalation, reduced nephrotoxicosis, and increased remission rates in the treatment previously poorly responsive malignant tumors in human beings. A pilot study was performed to determine efficacy of 4-hour saline loading in providing renal protection for dogs receiving high-dose cisplatin (150 mg/m² IV). Two beagles were saline loaded (25 ml/kg/hr of 0.9% NaCI, IV) for 4 hours and infused with cisplatin (150 mg/m²). We demonstrated that high-dose cisplatin (150 mg/m² IV) can be administered to dogs without biochemical evidence of acute nephrotoxicosis; however gastrointestinal toxicoses (fibrinonecrotic enteritis) and severe myelosuppression (leukopenia) were incompatible with patient survival and therefore, dose limiting. In another study we compared efficacy of hypertonic saline with normal saline in preventing nephrotoxicosis associated with administration of high-dose cisplatin (90 mg/m² IV) to dogs. In this study we demonstrated that a single IV dose of cisplatin (90mg/m²) can be administered to dogs in normal saline (0.9%) or hypertonic saline (7%) in combination with 4 hour saline loading (25 ml/kg/hr) without evidence of reduced renal function as measured by exogenous creatinine clearance. Platelet numbers were significantly increased in dogs that received cisplatin in hypertonic saline. Nephrotoxicosis was not dose limiting in either study. Future studies should attempt to determine the efficacy and toxicoses of multiple doses of cisplatin (90 mg/M² administered in hypertonic saline to tumor bearing dogs.
- Detection of Feline Leukemia Virus in Feline Bone Marrow Using Polymerase Chain ReactionStimson, Erin Leigh (Virginia Tech, 2000-03-31)Latent feline leukemia virus (FeLV) infections, in which proviral DNA is integrated into host DNA, but not actively transcribed, are suspected to be associated with many diseases. Bone marrow is the suspected site of the majority of latent infections. The purpose of this study was to determine if polymerase chain reaction (PCR) could detect FeLV proviral DNA in bone marrow and provide a method of detecting latent infections. Blood and bone marrow samples from fifty cats and bone marrow from one fetus were collected; sixteen had FeLV-associated diseases. Serum ELISA, blood and bone marrow immunofluorescent antibody test (IFA), and blood and bone marrow PCR were performed on each cat, and IFA and PCR on bone marrow of the fetus. Forty-one cats were FeLV negative. Five cats and one fetus were persistently infected with FeLV. Four cats were discordant; two ELISA positive with other tests negative, one bone marrow IFA negative with other tests positive, and one bone marrow IFA positive with other tests negative. No cats were positive on bone marrow PCR only. These results indicate that PCR can detect FeLV in bone marrow, but no cats in this study harbored FeLV only in the bone marrow. Not all cats with FeLV-associated diseases are persistently or latently infected with FeLV.
- Effect of Levothyroxine Administration on Hemostatic Analytes in Doberman Pinschers with von Willebrand's DiseaseHeseltine-Heal, Johanna Colleen (Virginia Tech, 2004-04-23)This study tested the hypothesis that levothyroxine supplementation increases plasma von Willebrand factor (vWf) concentration and enhances vWf function. The effects of levothyroxine administration were evaluated in 8 euthyroid Doberman Pinschers with plasma vWf concentration <30%. Levothyroxine (0.04mg/kg PO q12hours) and placebo were administered for 30 days in a 2-period, 2-treatment, double-blinded, crossover design with a 30-day washout period between treatments. Buccal mucosal bleeding time (BMBT), vWf antigen concentration (vWf:Ag), vWf collagen binding activity (vWf:CBA), Factor VIII coagulant activity (FVIII:C), serum total thyroxine (T4), free thyroxine (fT4), 3,5,3â -triiodothyronine (T3), and thyroid stimulating hormone were measured on days 0, 2, and 30 of each treatment period. The dogs had markedly low plasma vWf:Ag concentrations (mean 8.9%; reference range 70-180%) and vWf:CBA (mean 11.1%; reference range >70%). All dogs had FVIII:C activity within reference range. The response to placebo versus active levothyroxine treatment revealed no significant differences between groups at any time for BMBT, vWf:Ag, vWf:CBA, and FVIII:C. Serum total thyroxine, fT4, and T3 were significantly higher in the levothyroxine-treated group compared to the placebo group at days 2 and 30. Thyroid stimulating hormone was significantly lower in the levothyroxine-treated group compared to the placebo group at days 2 and 30. Levothyroxine (0.04mg/kg) caused laboratory evidence of hyperthyroidism but did not affect plasma FVIII:C and vWf:Ag concentration or the vWf-dependent functional parameters of collagen binding and BMBT. The results of this study do not reveal a direct action of levothyroxine supplementation on plasma vWf concentration or activity in euthyroid Doberman Pinschers.
- The Effect of Nephrotomy on Renal Function and Morphology in Normal CatsKing, Michael David (Virginia Tech, 2006-05-02)Objective: To assess effects of bisection nephrotomy on renal function, size, and morphology in cats over a period of 12 weeks. Study Design: Controlled, randomized, blinded experiment. Sample Population: Ten adult female cats. Methods: Glomerular filtration rate (GFR), as determined by quantitative renal scintigraphy using 99mTc-DTPA, urinalysis, urine culture, and sonographic measurement of renal size were performed pre-operatively. A left or right nephrotomy (five randomly assigned cats in each group) was performed. Total and individual kidney GFRs were determined in each cat 2, 28 and 84 days post-operatively. Both kidneys were measured sonographically 28 and 86 days postoperatively and an ultrasound-guided biopsy of each kidney was obtained 86 days postoperatively. Results: No significant differences in mean GFR and kidney size of the operated versus un-operated kidneys were observed at any time period. Individual GFR and renal size of all except one of the cats remained within normal limits. Two additional cats had evidence of transient ureteral obstruction in the immediate post-operative period. No significant histologic abnormalities were observed in any biopsy. Conclusions: Bisection nephrotomy in normal cats did not adversely affect renal function or morphology over the three month post-operative period. Clinical Relevance: Bisection nephrotomy can be safely performed in normal feline kidneys without causing a significant deleterious effect on renal function. Studies in animals with pre-existing renal insufficiency are needed to insure no adverse effects would occur in clinical cases where this surgical procedure is warranted.
- Effects of a prostaglandin E₁ analogue, misoprostol, on gentamicin-induced nephrotoxicosis in dogsDavies, Charlotte (Virginia Tech, 1996-08-30)Autoregulation of renal blood flow is partly mediated by antagonistic vasodilating and vasoconstricting effects of products of the arachidonic acid cascade. Vasodilatory prostaglandins have been evaluated in experimental models of acute renal failure and clinical human medicine, with variable results. This study assessed potential protective effects of an oral prostaglandin E₁ analogue, misoprostol, in gentamicin-induced nephrotoxicosis in dogs. Twelve dogs were initially assessed to be clinically healthy and to have normal renal function. Each received gentamicin (10 mg/kg intravenously, every 8 hours) for 8 days. Six dogs received oral placebo and 6 received misoprostol (3 µg/kg by mouth, every 8 hours) for the duration of study. Serum biochemical profiles, urinalyses, and exogenous creatinine clearances were monitored every 2 to 3 days. Three dogs receiving misoprostol were withdrawn early because of severity of clinical signs. Changes in serum urea nitrogen, creatinine, potassium, chloride, total protein, and urine protein-to-creatinine ratio appeared more severe in dogs receiving misoprostol, but were not significantly different between groups over time. Exogenous creatinine clearances were significantly decreased in dogs receiving misoprostol. Histopathological changes included patchy necrosis of renal proximal and were not significantly different between groups. Administration of misoprostol appeared to adversely affect glomerular filtration rates in this model of acute nephrotoxicosis in dogs. In previous studies, supplementing vasodilatory prostaglandins in experimental acute renal failure had beneficial effects or there were no changes in renal function. Additional study is needed to assess effects of manipulating vasoactive products of the arachidonic acid cascade in renal failure.
- Effects of Blood Contamination on Cerebrospinal Fluid Cell Counts, Protein, and D-dimer ConcentrationsRossmeisl, John H. Jr. (Virginia Tech, 2003-01-20)Cerebrospinal fluid analysis (CSF) is commonly performed in clinical neurology, and is a sensitive, but non-specific indicator of central nervous system (CNS) pathology. Blood contaminated CSF samples have the potential to adversely affect results of cytologic, serologic, microbiologic, and molecular biologic diagnostics. A clear consensus of the effects of blood contamination on CSF analysis could not be drawn following a review of the existing veterinary literature. Based on data from earlier reports, it was hypothesized that iatrogenic blood contamination of CSF would result in significant increases in both the CSF total protein (TP) concentration and nucleated cell count (WBC). As hypothesized, in vitro CSF blood contamination resulted in statistically significant (p < 0.01) linear increases in both the CSF TP and WBC with increasing RBC concentration in CSF from sixteen normal dogs. Although increases in TP and WBC are statistically significant, their clinical impact is negligible. Results of this study demonstrate that in normal dogs, the mean CSF TP concentration collected from the cerebellomedullary cistern, is lower than previously reported. D-dimers are plasminolytic cleavage products formed by the cross-linkage of fibrin by Factor XIIIa. In humans, D-dimer analysis can be used to differentiate iatrogenic from pathologic CNS hemorrhage. An additional objective of this study was to determine if canine D-dimers could be assayed using commercially available latex agglutination (LA) and enzymatic immunoassay (EIA) kits in normal and diseased subjects. It was hypothesized that qualitative and quantitative determinations of blood and CSF D-dimer activities could be aid in the diagnosis of dogs with altered CNS and/or systemic coagulation. D-dimers were able to be assayed in all subjects studied. D-dimer concentrations in CSF samples, when analyzed using a qualitative LA assay system, from healthy dogs with iatrogenically blood contaminated CSF were consistently negative. Quantitation of CSF D-dimer concentrations in normal dogs using an EIA assay resulted in lower values (mean 16.2 + 4.3 ng/ml; range, 0 to 54 ng/ml) than detected in the peripheral blood of dogs and humans (normal cutoff value < 250 ng/ml). These findings suggest that D-dimer formation does not occur in canine CSF freshly contaminated with blood. Significantly (p < 0.001) higher mean blood D-dimer concentrations were present in dogs with systemic coagulation disorders (1,093.4 + 172.3 ng/ml; range, 0 to > 2,000 ng/ml) when compared to normal dogs (54.6 + 19.8 ng/ml; range, 0 to 190 ng/ml), when assayed with the EIA. When used as an adjunct in the diagnosis of systemic coagulation abnormalities, the EIA assay had an overall sensitivity of 92%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value (NPV) of 94%. When applied to the same dogs, the LA D-dimer was less sensitive and specific (sensitivity of 73%, specificity of 100%, PPV of 100%, and NPV of 80%) than the EIA. Evidence of intrathecal fibrinolysis in the absence of systemic abnormalities was also demonstrated using CSF LA and EIA D-dimer assays in some dogs with a variety of infectious (Rocky mountain spotted fever), non-infectious inflammatory (granulomatous meningoencephalitis, steroid-responsive meningitis), traumatic (intervertebral disc disease, spinal fracture), and neoplastic (meningioma) diseases. When all dogs with CNS diseases were examined together, the mean EIA D-dimer concentration was significantly (p = 0.03) higher (511.6 + 279.8 ng/ml) than normal dogs (mean 16.2 + 4.3 ng/ml). Future studies will be required before the definitive role of D-dimer analysis can be defined in veterinary medicine.
- The effects of indwelling transurethral catheterization and tube cystostomy on urethral anastomoses in dogsCooley, Anjilla Joye (Virginia Tech, 1996-05-05)This study compared the effects of urinary diversion by tube cystostomy catheterization, urethral catheterization and tube cystostomy and urethral catheterization on healing urethral anastomoses in the canine urethra. Fifteen intact, mature males were divided into three groups of five dogs. Urodynamic studies were performed under halothane anesthesia preoperatively and at ten weeks postoperatively. Urethral anastomosis was performed in all dogs over a urethral catheter with 4-0 polyglyconate. Group U dogs (n=5) received transurethral catheters. Group C dogs (n=5) received tube cystostomy catheters, and Group B dogs (n=5 ) had both a transurethral catheter and a cystostomy tube placed. All dogs had catheters maintained with a closed urine collection system for seven days. Dogs were observed for ten weeks following surgery, and urinalysis and urine cultures were performed on weeks 1, 4, and 8. Preoperative evaluations were repeated ten weeks postoperatively just prior to termination of the study. Radiographic and histopathologic evaluation of the urethral specimen was performed. No significant differences among the groups were noted after the second postoperative week when comparing observation scores for urination and posturing. Measurements made on in-vivo and in-vitro urethrographic studies revealed less luminal reduction at the anastomotic site in Group C when compared to Groups B and U. Results of this study indicated that urinary diversion by tube cystostomy will minimize the percent luminal diameter reduction (PLDR) when compared to transurethral catheterization alone and tube cystostomy combined with transurethral catheterization. The author recommends tube cystostomy be considered for urinary diversion following primary closure of urethral defects due to the ease of maintenance and increased patient tolerance of the technique.
- Effects of Levothyroxine Adminstration and Withdrawal on the Hypothalamic-Pituitary-Thyroid Axis in Euthyroid DogsZiglioli, Vincent (Virginia Tech, 2016-05-17)Background: Because of the vague clinical signs and limitations of thyroid function tests, misdiagnosis of hypothyroidism in dogs is common and leads to inappropriate treatment with levothyroxine. Chronic supplementation can suppress the hypothalamic-pituitary-thyroid axis (HPTA) and make it difficult to assess thyroid function following withdrawal of levothyroxine. Objectives: To determine if the HPTA is suppressed following levothyroxine administration in euthyroid dogs and the time required for resolution of any suppression. Animals: Twenty-eight healthy euthyroid dogs Methods: A prospective randomized study administering levothyroxine to euthyroid dogs with levothyroxine, for either 8 weeks (group 1) or 16 weeks (group 2). Serum concentrations of total thyroxine (T4), free thyroxine (fT4) by equilibrium dialysis, thyrotropin (TSH), and 3,5,3'-triiodothyronine (T3) were measured every 4 weeks during supplementation and for 16 weeks after levothyroxine was discontinued. Results: Mean serum T4 and fT4 were significantly higher and TSH was lower in all dogs during levothyroxine administration compared to baseline. Mean serum concentrations of T4 and fT4 in both groups and TSH in group 1, beginning 1 week after levothyroxine was discontinued, were significantly different compared to values during levothyroxine administration but not compared to baseline values. Conclusions and Clinical Importance: Suppression of the HPTA occurred during levothyroxine supplementation and mean serum T4, fT4 and TSH concentrations were not significantly different compared to baseline 1 week after discontinuation in both groups. Assessing thyroid function tests 1 week after cessation of levothyroxine will likely provide an accurate assessment of thyroid function in euthyroid dogs.
- The Effects of Prednisone and Prednisone Plus Ultralow-dose Aspirin on Coagulation Parameters in Healthy DogsO'Kell, Allison Louise (Virginia Tech, 2012-01-27)Objectives: To determine the effects of prednisone and prednisone plus ultralow-dose aspirin on coagulation in healthy dogs, and to determine intra-individual variation in thromboelastography (TEG). Animals: 14 healthy experimental dogs and 10 healthy client-owned dogs Procedures: Prospective, randomized, blinded study. TEG was performed twice three days apart on each experimental dog prior to treatment and intra-individual variation was calculated. Dogs were given prednisone (2 mg/kg/day) plus aspirin (0.5 mg/kg/day) or prednisone (2 mg/kg/day) plus placebo for 14 days, after which TEG and other baseline tests were repeated. Changes from baseline between and within each group were compared using t-tests or Wilcoxon 2 sample tests. Client owned dogs had TEG performed twice three days apart to determine intra-individual variation. Results: Intra-individual variation in TEG parameters were <10% for MA (maximum amplitude) and angle. For experimental dogs, MA and fibrinogen significantly increased from baseline whereas Ly30 (percent lysis 30 minutes after MA) and antithrombin activity significantly decreased within each group. For the prednisone plus placebo group, Ly60 (percent lysis 60 minutes after MA) significantly decreased from baseline. For all parameters, there was no difference between groups for change from baseline. Conclusions and Clinical Relevance: Prednisone caused hypercoagulability in healthy dogs evidenced by increased MA and fibrinogen and decreased antithrombin activity. Concurrent use of ultra-low dose aspirin had no effect on measured TEG parameters. Intra-individual variation in some TEG parameters is high and may preclude routine clinical utility.
- Effects of Prednisone or Prednisone with Ultralow-Dose Aspirin on the Gastroduodenal Mucosa of Healthy DogsGraham, Allison Heather (Virginia Tech, 2009-03-20)This study tested the hypothesis that administration of immunosuppressive doses of prednisone in conjunction with ultralow-dose aspirin (0.5 mg/kg/day) would result in gastroduodenal lesion scores similar to those found in dogs administered only immunosuppressive doses of prednisone, but that the gastroduodenal scores from both of these treatment groups would be significantly higher than placebo when administered to healthy dogs for 27 days. Eighteen healthy adult purpose-bred dogs were divided randomly into three groups. Group I received placebo capsules and placebo suspension, Group II received prednisone capsules (mean 2.3 mg/kg, range 2.0-2.4) and placebo suspension, and Group III received prednisone capsules (mean 2.3 mg/kg, range 2.3-2.5) and aspirin suspension (0.5 mg/kg) by mouth once daily for 27 days. Gastroduodenoscopy was performed on days -7 (baseline), 5, 14, and 27 of treatment. Four regions of the stomach (angularis incisura, body, pylorus, and cardia) and the proximal descending duodenum were systematically scored on a scale of 1 (normal) to 11 (perforating ulcer) by an experienced observer who was blinded to the treatment groups and clinical signs of each subject. Dogs were observed every 8 hours for vomiting, diarrhea, and inappetence. Feces were scored on a scale of 1-5 with diarrhea defined as a fecal score <4. Lesion scores for each group, at each location, and total scores, at each time period were evaluated for the effects of time and treatment using a Kruskal-Wallis test. Total dog days of vomiting and dog days of diarrhea in each group were compared using a Wilcoxon rank sums test. Significance was determined at p<0.05. There were no significant differences in median total gastric lesion scores between any of the groups at any time during the study. There was no location effect on regional gastroduodenal lesion scores and there was no significant change in gastroduodenal lesion scores over time in any of the groups during treatment. Significantly more dog-days of diarrhea occurred within the prednisone and aspirin group during the experimental period (Period 2) in comparison to Period 1. However, no significant differences were found between any of the groups for dog-days of vomiting, diarrhea or inappetence at any time in the study.
- Feline Leukemia Virus Detection in Corneal Tissues of Cats by Polymerase Chain Reaction and ImmunohistochemistryHerring, Ian Phillip (Virginia Tech, 1998-04-27)Corneal transplantation carries a high rate of success in the domestic cat and is an indicated treatment for specific corneal diseases in this species. The potential for iatrogenic transmission of viral diseases is a well-recognized problem in human corneal transplantation programs and screening donors for certain diseases is routine. Feline leukemia virus (FeLV) is a common agent of disease in domestic cats and available blood tests are highly effective in identification of infected individuals. This study investigates the presence of FeLV within corneal tissues of FeLV infected cats. Seventeen cats were identified to be positive for serum p27 antigen by enzyme-linked immunosorbent assay (ELISA). Twelve of these individuals were found to be positive on peripheral blood by immunofluorescent antibody (IFA) testing. Seventeen ELISA negative cats were identified to serve as negative controls. Full thickness corneal specimens were collected from all subjects and analyzed for the presence of FeLV proviral DNA and gp70 antigen by polymerase chain reaction (PCR) and immunohistochemical (IHC) testing, respectively. Eleven (64.7%) positive corneal PCR results were obtained from 17 ELISA positive cats. Of 12 cats which were both ELISA and IFA positive on peripheral blood, 10 (83.3%) had positive corneal PCR results. All corneal tissues from ELISA negative subjects were PCR negative. IHC staining of corneal sections revealed the presence of FeLV gp70 in corneal tissues of nine (52.9%) ELISA positive cats. Of the 12 cats which were both ELISA and IFA positive on peripheral blood, 8 (66.7%) had positive corneal IHC results. Positive IHC staining was localized to the corneal epithelium. Corneal tissues of all ELISA negative cats and all IFA negative cats were negative on IHC testing. This study reveals FeLV to be present within the corneal epithelium of some FeLV infected cats. Screening potential corneal donors for this virus is warranted. This work was funded by grants from the American College of Veterinary Ophthalmologists, the Virginia Veterinary Medical Association Pet Memorial Fund, and the DSACS Quick Response Fund.
- Peroxidative protection of parenteral admixture by d-α-tocopherol and its effect on oxidative status of obese catsBecvarova, Iveta (Virginia Tech, 2006-03-30)High lipid : low dextrose (HL:LD) parenteral admixture (PA) is high in polyunsaturated fatty acids (PUFA) that are sensitive to peroxidation. This study evaluated the antioxidative effect of vitamin E in both HL:LD PA and in obese cats given HL:LD PA. Natural d-α-tocopherol (Vital E-300) was added to HL:LD PA at seven concentrations (8, 12, 16, 24, 32, 48, or 64 IU/g of lipid). PA were exposed to fluorescent light for 24 hours at room temperature. Hydroperoxides were measured at baseline and 24 hours hang time. Significantly lower hydroperoxide concentrations were found with > 24 IU/g of lipid at baseline (P < 0.01). A higher d-α-tocopherol concentration was required (> 48 IU/g lipid) to lower hydroperoxides at 24 hours (P < 0.0001). HL:LD PA with 40 IU/g lipid/day d-α-tocopherol was delivered intravenously to obese cats (PA Toc⁺) over 48 hours. Control cats (PA Toc⁻) received HL:LD PA without a d-α-tocopherol supplementation. Oxidative status of cats was evaluated at baseline and 24, 48, and 96 hours. Cats in both groups exhibited an increase in MDA concentration (time effect; P < 0.0001). WBC-tGSH and WBC-GPx did not change in either group of cats. RBC-tGSH and RBC-GPx changed over time (time effects; P = 0.0005; P = 0.0016, respectively) with the PA Toc⁺ cats exhibiting a higher RBC-tGSH concentration (treatment x time interaction; P = 0.012). Serum α- and γ-tocopherol concentrations increased in PA Toc⁺ cats (treatment effect; P < 0.0001). These findings suggest that d-α-tocopherol significantly alters oxidative status in vivo.
- Technique for Repeatable Hyperosmotic Blood-Brain Barrier Disruption in the DogCulver, Britt Wayne (Virginia Tech, 1997-06-16)Reversible hyperosmotic blood-brain barrier disruption (BBBD) has been used in pharmaceutical research as well as human medicine to enhance drug delivery across the blood-brain barrier. However a technique for repeatable BBBD in the canine has not been described. This study describes a repeatable technique for BBBD in the dog and evaluates the clinical and morphological effects of BBBD. Using fluoroscopic guidance, an arterial catheter was directed into the internal carotid artery via the femoral artery in ten dogs. BBBD was achieved in 5 dogs using 25% mannitol while 5 control dogs received only saline. Following recovery, dogs were monitored for clinical signs before a second, non-survival procedure was performed 2-3 weeks later. BBBD was estimated using CT densitometry as well as Evan's blue staining on post-mortem exam. Histopathological evaluation of the brain was performed on all dogs. Seven dogs completed the study. Two treatment dogs were lost after the first infusion with deteriorating neurologic function attributed to CNS edema and increased intracranial pressure. One control dog was lost due to vessel wall damage during catheterization. The remaining dogs exhibited only transient neurologic, ocular, and vasculature injury. Successful BBBD was demonstrated in all treatment dogs as evidenced by CT and Evan's blue staining. Histopathological evaluation revealed multifocal areas of infarction in all dogs indicating refinement of the technique is needed. This study shows that repeatable disruption the BBB in the dog is possible and opens the way for further investigations of BBBD using the dog as a model.
- Transplacental transmission of a North American isolate of Leishmania infantum in an experimentally infected beagleRosypal, A. C.; Troy, Gregory C.; Zajac, Anne M.; Frank, G.; Lindsay, David S. (American Society of Parasitology, 2005-08)Leishmania infantum, an etiologic agent of zoonotic visceral leishmaniasis, is widespread among foxhounds in the United States. Although sand flies are widely distributed throughout the United States, epidemiological data do not support a major role for sand flies in the transmission of L. infantum in foxhounds in this country. Congenital transmission of human visceral leishmaniasis is reported in humans and might also occur in dogs. We have previously isolated L. infantum from Virginia foxhounds and used this isolate (LIVT-1) to experimentally infect beagles. Four female beagles, chronically infected with LIVT-I, were bred to a male beagle chronically infected with L. infantum chagasi. One beagle was able to maintain her pregnancy, and 4 puppies were delivered by cesarean section. One puppy was malformed and autolytic at delivery, and tissues were not collected or analyzed. The remaining puppies were killed at the time of cesarean section, and selected tissues were collected for parasite culture and PCR. Promastigotes were not cultured from tissues in any of the puppies. Leishmania sp. DNA was detectable by PCR in liver, bone marrow, and heart from all 3 puppies and in the spleen, lymph node, kidney, and placenta in 2 puppies. Placental tissue from the dam was PCR negative. This is the first report of maternal transmission of a North American isolate of L. infantum from an experimentally infected dog.