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  • Author or Editor: Kim M. Newkirk x
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Abstract

Objective—To determine whether epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) are expressed in periocular squamous cell carcinomas (SCCs) of horses.

Sample—Biopsy specimens of SCCs from 46 horses.

Procedures—Pathology records were searched retrospectively for biopsy specimens of periocular SCCs obtained from horses. Slides of the specimens were reviewed histologically to confirm the SCC diagnosis and stained for EGFR and HER2 by immunohistochemical methods. For both EGFR and HER2, the immunohistochemical staining intensity and percentage of stain-positive cells on the slides were determined.

Results—43 of 46 (93%) SCCs were immunoreactive for EGFR. The median score for EGFR staining intensity was 4 (range, 2 to 12), and the median number of mitotic figures was 8 mitotic figures/10 hpfs (range, 0 to 34 mitotic figures/10 hpfs). Mitotic index was not correlated with the percentage of EGFR stain–positive cells or staining intensity. Of the 43 EGFR-immunoreactive SCCs, 38 had stain present primarily in the cytoplasm and 5 had stain equally distributed between the cytoplasm and cell membranes. Thirty-five of 46 (76%) SCCs were immunoreactive for HER2. Mitotic index was not correlated with the percentage of HER2 stain–positive cells or staining intensity. Of the 35 HER2-immunoreactive SCCs, the stain was present primarily in the cytoplasm and 7 had stain equally distributed between the cytoplasm and cell membranes.

Conclusions and Clinical Relevance—Results indicated that most periocular SCCs of horses expressed EGFR and HER2, which suggested that equine periocular SCCs might respond to treatment with EGFR inhibitors.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To assess insulin, glucagon, and somatostatin expression within pancreatic islets of horses with and without insulin resistance.

ANIMALS 10 insulin-resistant horses and 13 insulin-sensitive horses.

PROCEDURES For each horse, food was withheld for at least 10 hours before a blood sample was collected for determination of serum insulin concentration. Horses with a serum insulin concentration < 20 μU/mL were assigned to the insulin-sensitive group, whereas horses with a serum insulin concentration > 20 μU/mL underwent a frequently sampled IV glucose tolerance test to determine sensitivity to insulin by minimal model analysis. Horses with a sensitivity to insulin < 1.0 × 10−4 L•min−1•mU−1 were assigned to the insulin-resistant group. All horses were euthanized with a barbiturate overdose, and pancreatic specimens were harvested and immunohistochemically stained for determination of insulin, glucagon, and somatostatin expression in pancreatic islets. Islet hormone expression was compared between insulin-resistant and insulin-sensitive horses.

RESULTS Cells expressing insulin, glucagon, and somatostatin made up approximately 62%, 12%, and 7%, respectively, of pancreatic islet cells in insulin-resistant horses and 64%, 18%, and 9%, respectively, of pancreatic islet cells in insulin-sensitive horses. Expression of insulin and somatostatin did not differ between insulin-resistant and insulin-sensitive horses, but the median percentage of glucagon-expressing cells in the islets of insulin-resistant horses was significantly less than that in insulin-sensitive horses.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that, in insulin-resistant horses, insulin secretion was not increased but glucagon production might be downregulated as a compensatory response to hyperinsulinemia.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate agents used for delivery of small interfering RNAs (siRNAs) into feline corneal cells, toxicity of the delivery agents, and functionality of anti-feline herpesvirus 1 (FHV-1)–specific siRNA combinations.

Sample—Feline primary corneal cells and 19 six-month-old colony-bred cats.

Procedures—siRNA delivery into corneal cells via various delivery agents was evaluated via flow cytometric detection of labeled siRNAs. Cellular toxicity was evaluated with a proliferation assay. Functionality was tested via quantitative reverse transcriptase PCR assay, plaque assay, and flow cytometry. In vivo safety was evaluated with an ocular scoring method following topical application of delivery agents containing siRNAs into eyes. Corneal biopsy specimens were used to assess safety and uptake of siRNAs into corneal cells.

Results—Use of 3 delivery agents resulted in > 95% transfection of primary corneal cells. Use of a peptide for ocular delivery yielded approximately 82% transfection of cells in vitro. In cultured corneal cells, use of the siRNA combinations resulted in approximately 76% to 89% reduction in FHV-1–specific mRNA, 63% to 67% reduction of FHV-1–specific proteins in treated cells, and 97% to 98% reduction in FHV-1 replication. The agents were nonirritating in eyes, caused no substantial clinical ocular signs, and were nontoxic. Histologically, corneal epithelium and stroma were normal in treated cats. However, none of the agents were effective in delivering siRNAs into the corneal cells in vivo.

Conclusions and Clinical Relevance—The tested anti–FHV-1–specific siRNAs could potentially be used as a treatment for FHV-1 if a successful means of in vivo delivery can be achieved.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate first-intention healing of CO2 laser, 4.0-MHz radiowave radiosurgery (RWRS), and scalpel incisions in ball pythons (Python regius).

Animals—6 healthy adult ball pythons.

Procedures—A skin biopsy sample was collected, and 2-cm skin incisions (4/modality) were made in each snake under anesthesia and closed with surgical staples on day 0. Incision sites were grossly evaluated and scored daily. One skin biopsy sample per incision type per snake was obtained on days 2, 7, 14, and 30. Necrotic and fibroplastic tissue was measured in histologic sections; samples were assessed and scored for total inflammation, histologic response (based on the measurement of necrotic and fibroplastic tissues and total inflammation score), and other variables. Frequency distributions of gross and histologic variables associated with wound healing were calculated.

Results—Gross wound scores were significantly greater (indicating greater separation of wound edges) for laser incisions than for RWRS and scalpel incisions at all evaluated time points. Necrosis was significantly greater in laser and RWRS incisions than in scalpel incision sites on days 2 and 14 and days 2 and 7, respectively; fibroplasia was significantly greater in laser than in scalpel incision sites on day 30. Histologic response scores were significantly lower for scalpel than for other incision modalities on days 2, 14, and 30.

Conclusions and Clinical Relevance—In snakes, skin incisions made with a scalpel generally had less necrotic tissue than did CO2 laser and RWRS incisions. Comparison of the 3 modalities on the basis of histologic response scores indicated that use of a scalpel was preferable, followed by RWRS and then laser.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine degrees of production of cyclooxygenase (COX)-1 and -2 and other mediators of inflammation in noninflamed and inflamed skin and muscle tissues in ball pythons (Python regius).

ANIMALS 6 healthy adult male ball pythons.

PROCEDURES Biopsy specimens of noninflamed skin and muscle tissue were collected from anesthetized snakes on day 0. A 2-cm skin and muscle incision was then made 5 cm distal to the biopsy sites with a CO2 laser to induce inflammation. On day 7, biopsy specimens of skin and muscle tissues were collected from the incision sites. Inflamed and noninflamed tissue specimens were evaluated for production of COX-1, COX-2, phosphorylated protein kinase B (AKT), total AKT, nuclear factor κ-light-chain-enhancer of activated B cells, phosphorylated extracellular receptor kinases (ERKs) 1 and 2, and total ERK proteins by western blot analysis. Histologic evaluation was performed on H&E-stained tissue sections.

RESULTS All biopsy specimens of inflamed skin and muscle tissues had higher histologic inflammation scores than did specimens of noninflamed tissue. Inflamed skin specimens had significantly greater production of COX-1 and phosphorylated ERK than did noninflamed skin specimens. Inflamed muscle specimens had significantly greater production of phosphorylated ERK and phosphorylated AKT, significantly lower production of COX-1, and no difference in production of COX-2, compared with production in noninflamed muscle specimens.

CONCLUSIONS AND CLINICAL RELEVANCE Production of COX-1, but not COX-2, was significantly greater in inflamed versus noninflamed skin specimens from ball pythons. Additional research into the reptilian COX signaling pathway is warranted.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To perform a qualitative analysis of the distribution of µ- and κ-opioid receptor mRNA in the forebrain and midbrain of budgerigars (Melopsittacus undulatus).

SAMPLE

8 brains of male budgerigars.

PROCEDURES

Custom-made RNA hybridization probes (RNAscope; Advanced Cell Diagnostics Inc) were used for fluorescent in situ hybridization (FISH) assays performed on selected fresh frozen prepared sections of brain tissue to identify µ- and κ-opioid receptor mRNA.

RESULTS

There was κ-opioid receptor mRNA present in the nucleus dorsomedialis posterior thalami, lateral striatum, mesopallium, tractus corticohabenularis et corticoseptalis, griseum et fibrosum, stratum griseum centrale, medial striatum, and area parahippocampalis. There was µ-opioid receptor mRNA present in the stratum griseum centrale, stratum opticum, dorsomedialis posterior thalami, area parahippocampalis, medial striatum, and nidopallium intermedium.

CLINICAL RELEVANCE

Consistent with previous studies in pigeons and domestic chicks, κ-opioid receptors were more abundant than µ-opioid receptors in the samples of the present study. The results of this study may also help explain the hyperexcitability or lack of response that can occur with administration of pure µ-opioid receptor agonists, but not κ-opioid receptor agonists. This study was not quantitative, so further research should endeavor to compare the various regions of the brain using FISH technology.

Open access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate effects of laser treatment on incisional wound healing in ball pythons (Python regius).

ANIMALS 6 healthy adult ball pythons.

PROCEDURES Snakes were sedated, a skin biopsy specimen was collected for histologic examination, and eight 2-cm skin incisions were made in each snake; each incision was closed with staples (day 0). Gross evaluation of all incision sites was performed daily for 30 days, and a wound score was assigned. Four incisions of each snake were treated (5 J/cm2 and a wavelength of 980 nm on a continuous wave sequence) by use of a class 4 laser once daily for 7 consecutive days; the other 4 incisions were not treated. Two excisional skin biopsy specimens (1 control and 1 treatment) were collected from each snake on days 2, 7, 14, and 30 and evaluated microscopically. Scores were assigned for total inflammation, degree of fibrosis, and collagen maturity. Generalized linear models were used to investigate the effect of treatment on each variable.

RESULTS Wound scores for laser-treated incisions were significantly better than scores for control incisions on day 2 but not at other time points. There were no significant differences in necrosis, fibroplasia, inflammation, granuloma formation, or bacterial contamination between control and treatment groups. Collagen maturity was significantly better for the laser-treated incisions on day 14.

CONCLUSIONS AND CLINICAL RELEVANCE Laser treatment resulted in a significant increase in collagen maturity at day 14 but did not otherwise significantly improve healing of skin incisions.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize the L1 gene of papillomaviruses detected in epithelial lesions of cats and to determine the relationship between those L1 gene nucleotide sequences and known L1 gene sequences of human and feline papillomaviruses.

Sample Population—10 tissue samples of epithelial lesions from 8 cats.

Procedures—DNA was extracted from tissue samples. Primers were designed to amplify the L1 gene of papillomaviruses. Amplicons of DNA were sequenced; nucleotide sequences were compared with known L1 gene nucleotide sequences of papillomaviruses and used for phylogenetic analysis.

Results—Tissue samples were obtained from lesions (diagnosed as dysplasia [n = 1], squamous cell carcinoma in situ [3], or squamous cell carcinoma [6]) of the skin (9) and oral mucosa [1]. Two amplicons had 99% homology with the L1 gene nucleotide sequence of human papillomavirus type 38b subtype FA125. Another amplicon had 84% homology with the L1 gene nucleotide sequence of human papillomavirus type 80 and was considered to be a new type of papillomavirus. Phylogenetic tree analysis revealed that these 3 papillomaviruses were grouped into 2 clades that were not similar to the clades of Felis domesticus papillomavirus type 1 or F domesticus papillomavirus type 2 (FdPV2). The remaining 7 amplicons had 98% to 100% homology with the L1 gene nucleotide sequence of FdPV2. Phylogenetic tree analysis revealed that those 7 papillomaviruses were grouped nto a single clade with FdPV2.

Conclusions and Clinical Relevance—Results support the likelihood of transmission of papillomaviruses between humans and cats.

Full access
in American Journal of Veterinary Research