Biomedical subjects

S J Withrow

Publications and source records attributed to S J Withrow.

At least 19 recordsLinked to original sources

PubMed2001

Spontaneous regression of osteosarcoma in four dogs.

Spontaneous regression of primary malignant bone tumors is rare but has been reported in the human literature. To the authors' knowledge, spontaneous regression of primary bone tumors in dogs or cats has not been reported. Osteosarcoma (OSA) is the most common primary bone tumor in humans, and it has been reported that the incidence of OSA is 40 to 50 times greater in dogs than humans. In this report, high-grade OSA was diagnosed in biopsy specimens obtained from 4 dogs that subsequently underwent spontaneous regression without tumor-specific treatment. Osteosarcoma in dogs has characteristics similar to that of OSA in humans.

Animals↗

PubMed2001

Clinical outcome of dogs with grade-II mast cell tumors treated with surgery alone: 55 cases (1996-1999).

OBJECTIVE: To determine outcome for dogs with grade-II mast cell tumors treated with surgery alone. DESIGN: Retrospective study. ANIMALS: 55 dogs. PROCEDURES: Medical records were examined, and signalment; location and size of tumor; staging status; dates of local recurrence, metastasis, death, or last follow-up examination; status of surgical margins; previous surgery; postoperative complications; and cause of death were recorded. Follow-up information was obtained via reexamination or telephone conversations with owners or referring veterinarians. Univariate analysis was performed to identify prognostic factors. RESULTS: 60 tumors in 55 dogs were included. Median follow-up time was 540 days. Three (5%) mast cell tumors recurred locally; median time to local recurrence was 62 days. Six (11%) dogs developed another mast cell tumor at a different cutaneous location; median time to a different location was 240 days. Three (5%) dogs developed metastases; median time to metastasis was 158 days. Fourteen dogs died; 3 deaths were related to mast cell tumor, and 7 were unrelated. The relationship with mast cell tumor was not known for 4. Median survival times were 151, 841, and 827 days, respectively, for these 3 groups. Forty-six (84%) dogs were free of mast cell tumors during the study period. A reliable prognostic factor could not be identified. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that additional local treatment may not be required after complete excision of grade-II mast cell tumors and that most dogs do not require systemic treatment.

Animals↗

PubMed2001

Treatment with a combination of doxorubicin, surgery, and radiation versus surgery and radiation alone for cats with vaccine-associated sarcomas: 25 cases (1995-2000).

OBJECTIVE: To compare use of doxorubicin, surgery, and radiation versus surgery and radiation alone for treatment of cats with vaccine-associated sarcoma. DESIGN: Retrospective study. ANIMALS: 25 cats with vaccine-associated sarcomas. PROCEDURE: Time to first recurrence and survival time were compared between the 2 treatment groups. The number of surgeries (1 or > 1) were compared with respect to time to first recurrence and survival time. RESULTS: Median time to first recurrence was 661 days for the group that received doxorubicin, surgery, and radiation. Median time to first recurrence has not yet been attained for the group treated with surgery and radiation alone. Median survival time was 674 days for the group treated with doxorubicin, surgery, and radiation and 842 days for the group treated with surgery and radiation alone. For time to first recurrence and survival time, significant differences were not detected between cats that had 1 surgery and those that had > 1 surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Significant differences between the 2 treatment groups were not detected. The efficacy of doxorubicin in the treatment of vaccine-associated sarcomas is uncertain.

Animals↗

PubMed2001

Effect of gas-plasma sterilization on the osteoinductive capacity of demineralized bone matrix.

The current study evaluated the effect of low-temperature hydrogen peroxide gas plasma sterilization on the osteoinductive capability of human demineralized bone matrix using a rat model. Twelve athymic rats received three separate implants consisting of steam-sterilized demineralized bone matrix (negative control), sterile-harvest demineralized bone matrix (positive control), and gas-plasma-sterilized demineralized bone matrix. A demineralized bone matrix pellet from each sterilization group was placed individually into one of three separate soft tissue pockets created in the epaxial musculature of each rat. All 12 rats were euthanized 9 weeks after implantation. Each implantation site was removed along with 0.5-cm normal tissue around the implant. Histologic examination was done on each implant site to determine the presence or absence of new bone, cartilage, or bone marrow elements. All 12 sterile harvest demineralized bone matrix sites histologically contained new bone elements, whereas none of the negative control or gas plasma sterilized demineralized bone matrix sites contained any of these same elements. The results of this study indicate that demineralized bone matrix sterilized with low-temperature, gas-plasma sterilization loses its osteoinductive capacity in a manner similar to that of steam-sterilized demineralized bone matrix, making low-temperature, gas- plasma sterilization unsuitable as a method of secondary sterilization of demineralized bone matrix.

Animals↗

PubMed2000

Use of orally administered carfentanil prior to isoflurane-induced anesthesia in a Kodiak brown bear.

A captive 590-kg (1,298-lb) 22-year-old castrated male Kodiak brown bear was evaluated because of a soft tissue mass in the right carpal and antebrachial regions. General anesthesia was deemed necessary on 3 occasions for various procedures including radiographic evaluation and biopsy, excision, and radiation treatment. The bear was given carfentanil orally to induce sedation, followed by i.m. administration of tiletamine-zolazepam (on 1 occasion) and atropine. Anesthesia was maintained by administration of isoflurane in oxygen. After each procedure, effects of carfentanil were reversed by administration of naltrexone. Although there was some variability, blood pressure, nasal temperature, heart rate, respiratory rate, oxygen saturation, PO2, and PCO2 remained within a clinically acceptable ranges.

Acid-Base Equilibrium↗

PubMed2000

Identification of matrix metalloproteinases in canine neoplastic tissue.

OBJECTIVE: To identify matrix metalloproteinases (MMP) 2 and 9 in canine tumor tissue and to compare the amount of activity to that in unaffected stromal tissue. ANIMALS: 30 dogs with spontaneously developing, high-grade osteosarcoma. PROCEDURE: Tumor and nearby stromal tissue (muscle) were obtained at the time of surgery. Specimens were homogenized, and supernatants were assayed, using gelatin zymography. Human derived standards were run concurrently. Densitometry was done to obtain a semiquantitative arbitrary unit value for each specimen. The amount of activity in tumor tissue was compared with the amount in stromal tissue. RESULTS: Gelatinolytic bands were observed from the analysis of all tumor tissues and in most stromal tissues. These bands migrated in the same molecular weight area as the human MMP 2 and 9 standards. Gelatinolytic activity could be quenched by the addition of 50 mM EDTA and 1 microg of synthetic tissue inhibitor of metalloproteinase (TIMP) 2 per 100 ml. There was significantly more gelatinolytic activity in tumor tissue than in stromal tissue. CONCLUSIONS AND CLINICAL RELEVANCE: MMP 2 and 9 are detectable in canine neoplastic tissue. Matrix metalloproteinases activity in tumor tissue is higher than in unaffected stromal tissue, indicating that canine MMP may be involved in the pathogenesis of tumor growth and metastasis.

Animals↗

PubMed1999

Effects of a controlled-release cisplatin delivery system used after resection of mammary carcinoma in mice.

OBJECTIVE: To evaluate efficacy of a controlled-release cisplatin delivery system, used after marginal resection of mammary carcinoma (ie, resection of grossly evident tumor) in mice, to prevent tumor regrowth and metastasis. ANIMALS: 42 female C3H-HeJ mice. PROCEDURE: Mice were inoculated with mammary carcinoma cells. Between 2 and 6 days later, tumors were marginally resected and mice were assigned to 1 of 3 groups: no treatment (control; n = 14), cisplatin administered intraperitoneally (i.p. cisplatin; 14), and cisplatin delivered by use of an open-cell polylactic acid system placed within the tumor bed (slow-release cisplatin; 14). Tumor regrowth was measured daily. Mice were euthanatized 14 days after surgery, and complete necropsies were performed. RESULTS: Tumor regrowth was not detected in the slow-release cisplatin group; however, tumor regrowth was detected in 7 of 14 mice in the i.p. cisplatin group and 14 of 14 mice in the control group. Median (+/-SD) number of days to tumor regrowth was 13.5+/-0.64 and 7.79+/-0.87 in the i.p. cisplatin and control groups, respectively. Mice in the i.p. cisplatin group had significantly delayed tumor regrowth, compared with control mice. Metastases to lungs were detected in 8 of 14 control mice but were not detected in mice in either cisplatin treatment group. CONCLUSIONS AND CLINICAL RELEVANCE: The open-cell polylactic acid with cisplatin delivery system was successful in delaying local tumor regrowth and metastasis in mice with marginally resected mammary carcinoma. Use of a controlled-release cisplatin delivery system may be an effective adjunct treatment following excision of mammary carcinoma in humans and other animals.

Animals↗

PubMed1998

Prognostic importance of alkaline phosphatase activity in serum from dogs with appendicular osteosarcoma: 75 cases (1990-1996).

OBJECTIVE: To determine whether alkaline phosphatase activity in dogs with appendicular osteosarcoma can be used as a prognostic indicator. DESIGN: Retrospective study. ANIMALS: 75 dogs with appendicular osteosarcoma. PROCEDURE: Serum total alkaline phosphatase (TALP) and bone-specific alkaline phosphatase (BALP) activities were determined from archival serum samples obtained at various times during treatment of appendicular osteosarcoma and follow-up evaluations. Associations among activities of TALP and BALP and survival and disease-free intervals, percentage of bone length involved with tumor, histologic subtype, and method of surgical treatment were evaluated. RESULTS: High activities of TALP and BALP before surgery were significantly associated with shorter survival and disease-free intervals in dogs undergoing surgery (amputation or limb-sparing procedure) and adjuvant chemotherapy. Activity of BALP significantly decreased in 29 dogs for which postoperative samples were available. Failure of BALP activity to decrease after surgery was correlated with shorter survival and disease-free intervals. CLINICAL IMPLICATIONS: Activities of TALP and BALP in serum are important prognostic factors for appendicular osteosarcoma in dogs. Prognostic factors may help clinicians initiate more aggressive treatment for dogs that are at higher risk of death or relapse.

Alkaline Phosphatase↗

PubMed1998

The evolution of veterinary surgical oncology.

Tremendous change and progress have occurred in the field of oncology over the last several decades. Progression in diagnostic techniques, patient support, adjuvant therapies and surgeon training has allowed the field of surgical oncology to make continued improvements in the human cancer field. Although a relatively young field, veterinary surgical oncology has followed in the progressive footsteps of our human counterparts. This article describes the evolution of this rapidly expanding field of veterinary medicine.

Animals↗

PubMed1998

Preoperative patient planning and margin evaluation.

Preoperative assessment of the cancer patient can be broken down into: (1) What is it? (2) Where is it? and (3) What is the status of the patient? Evaluation of local disease begins with obtaining and interpreting cytologic or histologic (biopsy) samples. Tumor staging involves the assessment of tumor invasion into local tissues, draining lymph nodes, and distant sites, especially the pulmonary parenchyma. Staging is performed with the aid of imaging techniques and special procedures such as lymph node and bone marrow aspiration. Because many veterinary cancer patients are geriatric, examination of physiologic patient status through laboratory and other diagnostic avenues is vital to the appropriate selection and success of therapy. After these questions are answered, appropriate treatment options and an ultimate treatment plan can be formulated. This article describes logical and practical approaches for diagnosis, staging, patient assessment, and treatment planning of the animal presented with tumor disease. With appropriate preoperative assessment, we can offer our patients and clients the best care possible.

Animals↗

PubMed1998

Surgery for skeletal sarcomas.

Skeletal neoplasms in pet animals are uncommon, but can represent a diagnostic and treatment challenge for the veterinary clinician. Osteosarcoma represents the most common histology of primary bone tumor and although the prognosis after treatment is still gaurded, major strides have been made in the treatment of this disease. Treatment success, however, requires a multidisciplinary approach. Additional histologic types cannot be ignored from the diagnosis of cases presenting as bone neoplasms, and many of these can have excellent long-term prognoses if treated appropriately. This article discusses the presentation, diagnosis, and treatment of skeletal neoplasms in general with a specific emphasis on osteosarcoma.

Animals↗

PubMed1998

Principles of treatment for soft tissue sarcoma.

Soft tissue sarcomas (STS) are mesenchymal tumors arising from connective tissue elements and are grouped together based on a common biologic behavior. The most common histologic types include malignant peripheral nerve sheath tumors (schwannoma and neurofibrosarcoma) "hemangiopericytoma," fibrosarcoma, and malignant fibrous histiocytoma. These tumors are relatively slow growing yet locally invasive with a high rate of recurrence following conservative management. Appropriate preoperative planning and aggressive surgical resection often result in long-term remission or cure. Identification and evaluation of resection margins are paramount in appropriate case management. The addition of radiotherapy after surgical resection can aid in remission for incompletely resected masses. Systemic chemotherapy for STS should be considered for high-grade tumors with a moderate metastatic potential. Potential prognostic factors include grade, resection margins, size, location, histologic type, and previous treatment, with grade and margins being the most important. Tumor types classified as STS that differ slightly in their presentation or treatment, including synovial cell sarcoma, rhabdomyosarcoma, liposarcoma, and vaccine-associated STS in cats, are discussed. Soft tissue sarcomas can be a frustrating disease to treat, but adherence to solid surgical oncology principles can greatly increase the odds of good disease control.

Animals↗

PubMed1998

Preparation and in vitro characterization of gentamycin-impregnated biodegradable beads suitable for treatment of osteomyelitis.

A new method for preparing poly(L-lactide) (PLA) biodegradable beads impregnated with an ionic aminoglycoside, gentamycin, is described. The process employs hydrophobic ion pairing to solubilize gentamycin in a solvent compatible with PLA, followed by precipitation with a compressed antisolvent (supercritical carbon dioxide). The resulting precipitate is a homogeneous dispersion of the ion-paired drug in PLA microspheres. The microspheres are approximately 1 microm in diameter and can be compressed into beads (3-6 mm in diameter) strung on surgical sutures for implantation. The bead strings exhibit no significant change in release kinetics upon sterilization with a hydrogen peroxide plasma (Ster-Rad). The kinetics of gentamycin release from the PLA beads are consistent with a matrix-controlled diffusion mechanism. While nonbiodegradable poly(methyl methacrylate) (PMMA) beads initially release gentamycin in a similar manner, the drug release from PMMA ceases after 8 or 9 weeks, while the PLA beads continue to release drug for over 4 months. Moreover, only 10% of the gentamycin is released from the PMMA beads, while PLA beads release more than 60% of their load, if serum is present in the release medium. The PLA system displays improved release kinetics relative to PMMA, is biodegradable, is unaltered by gas sterilization, can be used for a range of antibiotics, and can be manipulated without disintegration. These are all desirable properties for an implantable drug delivery system for the prevention or treatment of osteomyelitis.

Absorption↗

PubMed1998