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  • Author or Editor: Elizabeth A. Carr x
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in Journal of the American Veterinary Medical Association


Objective—To assess the influence of tumor cell proliferation and sex-hormone receptors on the efficacy of megavoltage irradiation for dogs with incompletely resected meningiomas.

Design—Longitudinal clinical trial.

Animals—20 dogs with incompletely resected intracranial meningiomas.

Procedure—Dogs were treated with 48 Gy of radiation administered 3 times per week on an alternateday schedule of 4 Gy/fraction for 4 weeks, using bilateral parallel-opposed fields.

Results—Tumor proliferative fraction measured by immunohistochemical detection of proliferating cell nuclear antigen (PFPCNA index) ranged from 10 to 42% (median, 24%). Progesterone receptor immunoreactivity was detected in 70% of tumors. Estrogen receptor immunoreactivity was not detected. An inverse correlation was found between detection of progesterone receptors and the PFPCNA index. The overall 2-year progression-free survival (PFS) rate was 68%. The only prognostic factor that significantly affected PFS rate was the PFPCNA index. The 2-year PFS was 42% for tumors with a high PFPCNA index (value ≥ 24%) and 91% for tumors with a low PFPCNA index (value < 24%). Tumors with a high PFPCNA index were 9.1 times as likely to recur as were tumors with a low PFPCNA index.

Conclusions and Clinical Relevance—This study confirms the value of irradiation for dogs with incompletely resected meningiomas. Prognostic value of the PFPCNA index suggests that duration of treatment and interval from surgery to start of irradiation may affect outcome. Loss of progesterone receptors in some tumors may be responsible for an increase in PFPCNA index and may indirectly affect prognosis after radiation therapy. (J Am Vet Med Assoc 2000;216: 701–707)

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in Journal of the American Veterinary Medical Association


Objective—To determine the incidence of bovine papillomavirus (BPV) type 1 or 2 in sarcoids and other samples of cutaneous tissues collected from horses in the western United States.

Animals—55 horses with sarcoids and 12 horses without sarcoids.

Procedure—Tissue samples (tumor and normal skin from horses with sarcoids and normal skin, papillomas, and nonsarcoid cutaneous neoplasms from horses without sarcoids) were collected. Tissue samples were analyzed for BPV-1 or -2 DNA, using a polymerase chain reaction (PCR) and restriction fragment length polymorphism. The PCR products from 7 sarcoid- affected horses were sequenced to evaluate percentage homology with expected sequences for BPV-1 or -2.

Results—Most (94/96, 98%) sarcoids contained BPV DNA. Sixty-two percent of the tumors examined had restriction enzyme patterns consistent with BPV-2. Thirty-one of 49 (63%) samples of normal skin obtained from horses with sarcoids contained BPV DNA. All samples subsequently sequenced had 100% homology with the expected sequences for the specific viral type. All tissues from healthy horses, nonsarcoid neoplasms, and papillomas were negative for BPV DNA.

Conclusions and Clinical Relevance—Bovine papillomaviral DNA was detected in essentially all sarcoids examined. There appears to be regional variation in the prevalence of viral types in these tumors. The fact that we detected viral DNA in normal skin samples from horses with sarcoids suggests the possibility of a latent viral phase. Viral latency may be 1 explanation for the high rate of recurrence following surgical excision of sarcoids. (Am J Vet Res 2001;62:741–744)

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in American Journal of Veterinary Research


Objective—To determine expression of a transforming gene (E5) of bovine papillomavirus in sarcoids, other tumors, and normal skin samples collected from horses with and without sarcoids.

Sample Population—23 sarcoids and 6 samples of normal skin obtained from 16 horses with sarcoids, 2 samples of normal skin and 2 papillomas obtained from horses without sarcoids, and 1 papilloma obtained from a cow.

Procedure—Protein was extracted from tissue samples collected from horses and incubated with agarose beads covalently coupled to Staphylococcus aureus protein A and an anti-E5 polyclonal antibody. Following incubation, proteins were eluted from the beads and electrophoresed on a 14% polyacrylamide gel and transferred to a polyvinylidene difluoride membrane. The E5 protein was detected by use of western blot analysis, using a chemiluminescence detection system.

Results—All 23 sarcoids had positive results for expression of E5 protein. Quantity of viral protein appeared to vary among sarcoids. All other tissues examined had negative results for E5 protein. Highest expression for E5 protein was observed in biologically aggressive fibroblastic variants of sarcoids, compared with expression in quiescent tumors.

Conclusions and Clinical Relevance—This study documented that activation and expression of the E5 gene is evident in sarcoids obtained from horses. These data support the conclusion that infection with bovine papillomavirus is important in the initiation or progression of sarcoids in horses. Treatment strategies designed to increase immune recognition of virally infected cells are warranted. (Am J Vet Res 2001;62:1212–1217)

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in American Journal of Veterinary Research