Debra A. Kamstock

Nested Metamaterials for Wireless Strain Sensing

We designed, fabricated, and characterized metamaterial-based RF-microelectromechanical system (RF-MEMS) strain sensors that incorporate multiple split ring resonators (SRRs) in a compact nested architecture to measure strain telemetrically. We also showed biocompatibility of these strain sensors in an animal model. With these devices, our bioimplantable wireless metamaterial sensors are intended, to enable clinicians, to quantitatively evaluate the progression of long-bone fracture healing by monitoring the strain on the implantable fracture fixation hardware in real time. In operation, the transmission spectrum of the metamaterial sensor attached to the implantable fixture is changed when an external load is applied to the fixture, and from this change, the strain is recorded remotely. By employing telemetric characterizations, we reduced the operating frequency and enhanced the sensitivity of our novel nested SRR architecture compared to the conventional SRR structure. The nested SRR structure exhibited a higher sensitivity of 1.09 kHz/kgf operating at lower frequency compared to the classical SRR that demonstrated a sensitivity of 0.72 kHz/kgf. Using soft tissue medium, we achieved the best sensitivity level of 4.00 kHz/kgf with our nested SRR sensor. Ultimately, the laboratory characterization and in vivo biocompatibility studies support further development and characterization of a fracture healing system based on implantable nested SRR.

Evaluation of a xenogeneic VEGF vaccine in dogs with soft tissue sarcoma

Active immunization against pro-angiogenic growth factors or their receptors is an emerging strategy for controlling tumor growth and angiogenesis. Previous studies in rodent tumor models have indicated that immunization against xenogeneic growth factors is more likely to induce effective anti-tumor responses than immunization against the autologous growth factor. However, the effectiveness or safety of the xenogeneic vaccination approach has not been previously assessed in a clinically relevant outbred, spontaneous tumor model. Therefore, we investigated the safety and anti-tumor and anti-angiogenic effects of a xenogeneic vascular endothelial cell growth factor (VEGF) vaccine in pet dogs with spontaneous cancer. Nine dogs with soft tissue sarcoma were immunized with a recombinant human VEGF vaccine over a 16-week period. The effects of immunization on antibodies to human and canine VEGF, circulating VEGF concentrations, tumor microvessel density (MVD), and tumor growth were assessed. The xenogeneic VEGF vaccine was well-tolerated by all dogs and resulted in induction of humoral responses against both human and canine VEGF in animals that remained in the study long enough to receive multiple immunizations. Three of five multiply immunized dogs also experienced sustained decreases in circulating plasma VEGF concentrations and two dogs had a significant decrease in tumor MVD. The overall tumor response rate was 30% for all treated dogs in the study. We conclude therefore that a xenogeneic VEGF vaccine may be a safe and effective alternative means of controlling tumor growth and angiogenesis.

Expression profiling in canine osteosarcoma: identification of biomarkers and pathways associated with outcome

BackgroundOsteosarcoma (OSA) spontaneously arises in the appendicular skeleton of large breed dogs and shares many physiological and molecular biological characteristics with human OSA. The standard treatment for OSA in both species is amputation or limb-sparing surgery, followed by chemotherapy. Unfortunately, OSA is an aggressive cancer with a high metastatic rate. Characterization of OSA with regard to its metastatic potential and chemotherapeutic resistance will improve both prognostic capabilities and treatment modalities.MethodsWe analyzed archived primary OSA tissue from dogs treated with limb amputation followed by doxorubicin or platinum-based drug chemotherapy. Samples were selected from two groups: dogs with disease free intervals (DFI) of less than 100 days (n = 8) and greater than 300 days (n = 7). Gene expression was assessed with Affymetrix Canine 2.0 microarrays and analyzed with a two-tailed t-test. A subset of genes was confirmed using qRT-PCR and used in classification analysis to predict prognosis. Systems-based gene ontology analysis was conducted on genes selected using a standard J5 metric. The genes identified using this approach were converted to their human homologues and assigned to functional pathways using the GeneGo MetaCore platform.ResultsPotential biomarkers were identified using gene expression microarray analysis and 11 differentially expressed (p < 0.05) genes were validated with qRT-PCR (n = 10/group). Statistical classification models using the qRT-PCR profiles predicted patient outcomes with 100% accuracy in the training set and up to 90% accuracy upon stratified cross validation. Pathway analysis revealed alterations in pathways associated with oxidative phosphorylation, hedgehog and parathyroid hormone signaling, cAMP/Protein Kinase A (PKA) signaling, immune responses, cytoskeletal remodeling and focal adhesion.ConclusionsThis profiling study has identified potential new biomarkers to predict patient outcome in OSA and new pathways that may be targeted for therapeutic intervention.

Cranial mediastinal carcinomas in nine dogs

Nine dogs were diagnosed with cranial mediastinal carcinomas. Based on histological and immunohistochemical analysis, four dogs were diagnosed with ectopic follicular cell thyroid carcinomas, one dog with ectopic medullary cell thyroid carcinoma, two dogs with neuroendocrine carcinomas and two dogs with anaplastic carcinomas. Clinical signs and physical examination findings were associated with a space-occupying mass, although one dog was diagnosed with functional hyperthyroidism. Surgical resection was attempted in eight dogs. The cranial mediastinal mass was invasive either into the heart or into the cranial vena cava in three dogs. Resection was complete in six dogs and unresectable in two dogs. All dogs survived surgery, but four dogs developed pulmonary thromboembolism and two dogs died of respiratory complications postoperatively. Adjunctive therapies included pre-operative radiation therapy (n=1) and postoperative chemotherapy (n=3). Three dogs had metastasis at the time of diagnosis, but none developed metastasis following surgery. The overall median survival time was 243 days. Local invasion, pleural effusion and metastasis did not have a negative impact on survival time in this small case series.

Pamidronate functionalized nanoconjugates for targeted therapy of focal skeletal malignant osteolysis.

Significance Malignant osteolysis associated with inoperable primary bone tumors and multifocal skeletal metastases remains a challenging clinical problem in cancer patients. The outgrowth of residual cancer cells within the bone microenvironment despite aggressive multimodality therapies necessitates the discovery and validation of novel strategies for treating osteotropic solid tumors. We report on pamidronate functionalized polylactide nanoparticles for the targeted treatment of focal malignant osteolysis by delivering doxorubicin specifically to the bone tumor microenvironment. Improved efficacy was demonstrated in a preclinical orthotopic mouse model of osteosarcoma. Most importantly, through the inclusion of dogs with naturally developing osteosarcoma, biocompatibility, biodistribution, and anticancer activities at clinically relevant dosages were demonstrated in a large mammalian modeling system. Malignant osteolysis associated with inoperable primary bone tumors and multifocal skeletal metastases remains a challenging clinical problem in cancer patients. Nanomedicine that is able to target and deliver therapeutic agents to diseased bone sites could potentially provide an effective treatment option for different types of skeletal cancers. Here, we report the development of polylactide nanoparticles (NPs) loaded with doxorubicin (Doxo) and coated with bone-seeking pamidronate (Pam) for the targeted treatment of malignant skeletal tumors. In vivo biodistribution of radiolabeled targeted Pam-NPs demonstrated enhanced bone tumor accumulation and prolonged retention compared with nontargeted NPs. In a murine model of focal malignant osteolysis, Pam-functionalized, Doxo-loaded NPs (Pam-Doxo-NPs) significantly attenuated localized osteosarcoma (OS) progression compared with nontargeted Doxo-NPs. Importantly, we report on the first evaluation to our knowlege of Pam-Doxo-NPs in dogs with OS, which possess tumors of anatomic size and physiology comparable to those in humans. The repeat dosing of Pam-Doxo-NPs in dogs with naturally occurring OS indicated the therapeutic was well tolerated without hematologic, nonhematologic, and cardiac toxicities. By nuclear scintigraphy, the biodistribution of Pam-Doxo-NPs demonstrated malignant bone-targeting capability and exerted measurable anticancer activities as confirmed with percent tumor necrosis histopathology assessment.

Feline intestinal sclerosing mast cell tumour: 50 cases (1997-2008).

This case series presents a unique and unreported variant of feline intestinal mast cell tumour recognized at the CSU Veterinary Diagnostic Laboratory. Fifty cases of feline intestinal mast cell tumours described as having a significant stromal component were reviewed. Neoplastic cells formed a trabecular pattern admixed with moderate to abundant dense stromal collagen (sclerosis). Neoplastic cells had poorly discernible intracytoplasmic granules which demonstrated metachromasia with special histochemical stains consistent with mast cell granules. Additionally, a subset of cases stained for mast cell-specific tryptase and c-kit demonstrated positive immunoreactivity. Eosinophilic infiltrates were moderate to marked in almost all cases. Lymph node and hepatic metastases were present in 66% of the cases. Treatment and clinical outcome was available in 25/50 cases. Twenty-three of these patients died or were euthanized within 2 months of initial diagnosis. This is the first case series to characterize a sclerosing variant of intestinal mast cell tumour in the cat which appears to have a high propensity for metastasis and a guarded prognosis.

Reconstruction of Chest Wall Defects After Rib Tumor Resection: A Comparison of Autogenous, Prosthetic, and Composite Techniques in 44 Dogs

OBJECTIVE To compare short- and long-term outcome and complications of chest wall reconstruction in dogs using autogenous, prosthetic, and composite autogenous-prosthetic techniques. STUDY DESIGN Historical cohort. ANIMALS Dogs (n=44) with spontaneous tumors arising from or involving the chest wall. METHODS Medical records were reviewed for dogs with rib and/or sternal tumors treated by chest wall resection and reconstruction. Signalment, preoperative clinical features, intraoperative findings and complications, reconstruction technique (autogenous muscle flap, prosthetic mesh, or composite autogenous-prosthetic technique), and short- (< or =14 days) and long-term (>14 days) postoperative complications were determined from the medical records and telephone contact with owners and referring veterinarians. Associations between chest wall reconstruction technique and postoperative complications were tested with Cox proportional hazards. RESULTS Chest wall defects were reconstructed with autogenous muscle flaps (29 dogs), prosthetic mesh (3), and a composite technique of prosthetic mesh and either autogenous muscle or omental pedicle flap (12). Early postoperative complications were recorded in 8 dogs (18.2%) and included seroma (5) and pleural effusion and peripheral edema (3). One dog had a late complication (2.3%) with a mesh-related infection 767 days postoperatively. Overall, complications occurred in 10.3% of autogenous, 25.0% of composite, and 66.7% of prosthetic reconstructions. Chest wall reconstruction with Marlex mesh alone was associated with a significantly increased risk of postoperative complications compared with autogenous reconstruction (P=.027). Reconstruction of sternal defects (3), 2 of which were performed with Marlex mesh alone, was associated with a significantly increased risk of complications compared with lateral chest wall reconstructions (P=.037). CONCLUSIONS Large chest wall defects can be reconstructed with autogenous and composite techniques, but prosthetic mesh should be covered with well-vascularized autogenous muscle or omentum to decrease the risk of postoperative complications. Sternal defects should be reconstructed with rigid techniques. CLINICAL RELEVANCE Chest wall reconstruction with autogenous muscle flaps or a combination of autogenous techniques with prosthetic mesh is associated with a low rate of infection and other complications.

Correlation of Nodal Mast Cells with Clinical Outcome in Dogs with Mast Cell Tumour and a Proposed Classification System for the Evaluation of Node Metastasis

Lymph node metastasis in dogs with mast cell tumour has been reported as a negative prognostic indicator; however, no standardized histological criteria exist to define metastatic disease. The primary aim of this study was to determine whether different histological patterns of node-associated mast cells correlate with clinical outcome in dogs with mast cell tumour. A secondary goal was to propose a criteria-defined classification system for histological evaluation of lymph node metastasis. The Colorado State University Diagnostic Medicine Center database was searched for cases of canine mast cell tumours with reported lymph node metastasis or evidence of node-associated mast cells. Additional cases were obtained from a clinical trial involving sentinel lymph node mapping and node extirpation in dogs with mast cell neoplasia. Forty-one cases were identified for inclusion in the study. Demographic data, treatment and clinical outcome were collected for each case. Lymph nodes were classified according to a novel classification system (HN0-HN3) based on the number of, distribution of, and architectural disruption by, nodal mast cells. The findings of this study indicate that characterization of nodal mast cells as proposed by this novel classification system correlates with, and is prognostic for, clinical outcome in dogs with mast cell tumours.

Oncologic Outcome after Curative-Intent Treatment in 39 Dogs with Primary Chest Wall Tumors (1992–2005)

OBJECTIVE To describe the clinical features and determine oncologic outcome and prognostic factors for dogs with primary tumors of the osseous chest wall. STUDY DESIGN Historical cohort. ANIMALS Dogs (n=39) with spontaneous tumors involving the chest wall. METHODS Medical records were reviewed for dogs with rib and/or sternal tumors treated by chest wall resection and reconstruction. Signalment, preoperative clinical features, reconstruction technique, and oncologic outcome (local tumor recurrence, metastasis, and survival time) were determined from medical records and by telephone contact with owners and referring veterinarians. Oncologic outcome and prognostic factors were determined using Kaplan-Meier survival analysis and Cox proportional hazards. Logistic regression was used to determine if increased serum alkaline phosphatase (ALP) concentration was associated with tumor type. RESULTS Of the 39 dogs with tumors arising from the chest wall, 25 had osteosarcoma, 12 had chondrosarcoma, and 2 dogs had hemangiosarcoma. Median survival time (MST) for dogs with rib osteosarcoma was 290 days. Increased activity of total ALP significantly decreased survival in dogs with osteosarcoma (210 days versus 675 days, P=.0035). MST for dogs with rib chondrosarcoma was not reached (mean 1301 days) and survival was significantly greater than all other types of rib tumors (P=.0321). CONCLUSION Rib tumors should be resected with wide margins to decrease the risk of incomplete excision, because local tumor recurrence has a significant impact on the survival time. The prognosis for dogs with rib chondrosarcoma is very good, but guarded for other types of tumors. CLINICAL RELEVANCE Osteosarcoma and chondrosarcoma are the most common primary tumors of the chest wall. Prognosis for dogs with primary rib chondrosarcoma is very good with surgery alone, but surgery and adjunctive chemotherapy is recommended for dogs with primary rib osteosarcoma and the prognosis remains guarded.

Type I interferons inhibit the generation of tumor-associated macrophages

Tumor-associated macrophages (TAM) are very abundant in tumors and are thought to play a major role in promoting tumor growth. The generation of TAM is positively regulated by several cytokines, including colony stimulating factor-1 (CSF-1) and monocyte chemoattractant protein-1 (CCL2). However, endogenous factors that suppress the generation of TAM within tumors have not been previously identified. An earlier study showed that endogenously produced type I interferons (IFN) suppressed tumor growth via their effects on hematopoietic cells rather than through direct effects on tumor cells. Therefore, we used mouse tumor models to investigate the effects of endogenously produced type I IFNs on the generation of TAM. We found using immunohistochemistry and flow cytometry that TAM density was significantly increased in tumors of mice lacking the type I IFN receptor (IFN-α/βR−/− mice) compared to wild type mice. Moreover, the increase in TAM density was associated with a significant increase in tumor growth rate and angiogenesis. The phenotype of TAM was similar in IFN-α/βR−/− mice and wild type mice and tumors in both mice produced similar amounts of CSF-1 and CCL2. However, in vitro assays indicated that low concentrations of type I IFNs significantly inhibited the generation of bone marrow macrophages in response to CSF-1. These findings indicate that endogenously produced type I IFNs suppress the generation of TAM, which may in turn account for inhibition of tumor growth and angiogenesis.