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Biomedical subjects

C G Couto

Publications and source records attributed to C G Couto.

At least 55 records · Page 3Linked to original sources

Flow cytometric analysis of lectin-binding to canine blood lymphocytes.

The cell surface glycoconjugates of blood lymphocytes from 19 dogs with and without neoplastic disease were quantitated using flow cytofluorometric analysis of the binding characteristics of 3 lectins, namely, wheat germ agglutinin, concanavalin-A, and Lens culinaris agglutinin. The specificity of lectin binding was determined using competitive monosaccharide inhibitors. The results show enhanced binding of concanavalin-A to blood lymphocytes from dogs with lymphosarcoma relative to healthy dogs, or those with a variety of neoplastic and nonneoplastic diseases.

Animals↗

Comparison of two indwelling central venous access catheters in dogs undergoing fractionated radiotherapy.

Twenty dogs with neoplasms requiring multiple radiation treatments received either percutaneous vascular access catheters (PVACs; Cook, Bloomington, IN) or subcutaneous vascular access ports (SVAPs; Vascular-Access-Ports, Norfolk Medical Products, Inc., Skokie, IL); 10 dogs were entered in each group. All catheters were implanted and removed aseptically and the catheter tips were cultured during implant removal. Complications with PVACs included mild incisional swelling and redness and accidental severance or rupture of the catheter. Complications with SVAPs included incisional or port swelling, bruising or redness, hematoma formation, and pain. Ports in 4 of these dogs could not be used for 1 to 3 days after surgery because of swelling and pain. Surgical wound complications, when pooled for comparison, occurred significantly more frequently with the SVAPs (P = .023). Wound complications associated with both catheters were self-limiting and resolved within 7 days. Bacterial cultures were positive in two PVACs and four SVAP tips, however, none of these dogs had clinical signs of infection or sepsis. Although both types of indwelling catheters were functional in a clinical setting, PVACs were preferred to SVAPs for dogs undergoing radiation therapy because of decreased time for implantation and fewer overall complications.

Animals↗

Systemic mastocytosis in 16 dogs.

The clinical and pathologic features of systemic mastocytosis in 16 dogs are reported. There was no apparent breed or sex predilection, and the median age at presentation was 9.5 years. In 14 of 16 cases there was a primary cutaneous mast cell tumor (MCT). When cutaneous tumor location was compared with previous reports, there was no association between location and systemic dissemination. The most common presenting signs associated with the cutaneous tumor were regional dissemination, edema, ulceration, and abscessation. They were present in 12 dogs (69%). Signs of systemic illness, including anorexia, vomiting, and diarrhea, were seen in eight dogs (50%). Other than the cutaneous tumors, the most consistent physical and radiographic abnormalities included lymphadenopathy, splenomegaly, and hepatomegaly. Eosinophilia and basophilia were seen in two and five dogs, respectively. Six dogs had increased numbers of mast cells in peripheral blood or buffy coat smears. Five of the nine dogs evaluated had increased numbers of mast cells in bone marrow aspirates. Bone marrow aspiration was superior to both peripheral blood and buffy coat smears in predicting mastocytosis. Coagulation abnormalities were seen in three of five dogs tested. Using a conventional histomorphologic grading system, 10 of 13 (77%) tumors were classified as Grade III or undifferentiated and were overrepresented when compared with previous reports of cutaneous MCTs. Eighty-eight percent of the dogs either died or were euthanatized because of their tumors. Organs commonly involved at necropsy included lymph nodes, spleen, liver, and bone marrow; four dogs had gastroduodenal ulcers.

Animals↗

Fine-needle aspiration of the spleen as an aid in the diagnosis of splenomegaly.

Results from transabdominal fine-needle aspiration of the spleen in 28 dogs and 5 cats are reported. Splenomegaly was present in 79% of these patients, and splenic masses were present in 15%. Extramedullary hematopoiesis, the most common cytologic diagnosis, was found in 24% of the patients and was associated with a variety of diseases including immune hemolytic anemia, hemangiosarcoma, and bone marrow hypoplasia. Hematopoietic neoplasms including lymphosarcoma, plasmacytoma, myelogenous leukemia, and systemic mastocytosis were diagnosed in 24% of the patients. Other diagnoses included malignant neoplasia of undetermined cell type and lymphoreticular hyperplasia. Splenic aspirates were considered normal in 18% of the animals. Two (6%) of the aspirates contained liver tissue rather than spleen. Histologic evaluation of splenic tissue was performed in 42.5% of the patients. All cytologic diagnoses correlated well with their final histologic diagnoses. Complications from the aspiration procedure were not observed, even in thrombocytopenic patients.

Animals↗

Gastrointestinal lymphoma in 20 dogs. A retrospective study.

The records of 20 dogs with histopathologically diagnosed gastrointestinal (GI) lymphoma (LSA) evaluated between 1970 and 1984 were reviewed. Fifteen dogs were considered to have primary GI LSA, while five dogs had GI involvement in association with the multicentric form. Most clinical and laboratory findings were nonspecific, but positive-contrast upper GI radiography was suggestive of GI LSA in all of the dogs evaluated. Nine dogs had extensive lymphocytic-plasmacytic inflammatory infiltrates around the neoplastic foci, resulting in difficulty in obtaining a diagnosis of GI LSA when samples were obtained by endoscopy.

Animals↗

Tumor-associated erythrocytosis in a dog with nasal fibrosarcoma.

Erythrocytosis (hematocrit, 79%) was diagnosed in an 8-year-old, neutered female, mixed-breed dog with an intranasal fibrosarcoma. Both serum and tumor erythropoietin (Ep) activities were elevated, as determined by the polycythemic exhypoxic mouse model, and the Ep activity was neutralized in that model by rabbit anti-Ep antibodies. Tumor resection normalized the hematocrit.

Animals↗

Essential thrombocythemia in a cat.

The diagnosis of essential thrombocythemia in a cat was made by fulfilling the five applicable criteria set forth by the Polycythemia Vera Study Group for use in humans. The criteria were 1) a platelet count persistently above 600,000/microL, 2) a normal initial hematocrit that did not rise in response to iron therapy, 3) normal serum iron concentration, 4) absence of collagen fibrosis of the bone marrow, and 5) no cause for reactive thrombocytosis. In addition, normal thrombopoietin concentrations and splenic hypofunction were demonstrated. Melphalan was not effective in decreasing the platelet count and the cat died of sepsis.

Animals↗

Hemostatic abnormalities in dogs with hemangiosarcoma.

The hemostasis profiles of 24 dogs with histologically confirmed hemangiosarcoma were prospectively evaluated. Microangiopathic hemolysis was defined as the presence of schistocytes; disseminated intravascular coagulation was defined as 1) thrombocytopenia, 2) fibrin(ogen) degradation products greater than 10 micrograms/mL, 3) prolongation of one or more coagulation times (activated partial thromboplastin time or one-stage prothrombin time) by greater than 25% of the control, 4) fragmented red blood cells (greater than or equal to 1+ based on a semiquantitative grading scale), and 5) fibrinogen less than or equal to 80 mg/dL. Three of the five criteria listed above had to be met for disseminated intravascular coagulation to be diagnosed. Fifty percent of the dogs were considered to have disseminated intravascular coagulation at presentation. Thrombocytopenia was present in 75% of the dogs and was the most common abnormality. The mean platelet count was 137,800/microL. Twenty-five percent of the dogs died as a result of the hemostatic abnormalities. Only 12% of the dogs had microangiopathic hemolysis without other evidence of disseminated intravascular coagulation. Hemostatic abnormalities are present in many dogs with hemangiosarcoma at the initial clinical presentation and represent an important clinical finding.

Animals↗

Efficacy and toxicity of VAC chemotherapy (vincristine, doxorubicin, and cyclophosphamide) in dogs with hemangiosarcoma.

Fifteen dogs with hemangiosarcoma were treated with a combination of vincristine, doxorubicin, and cyclophosphamide after incisional or excisional biopsy. The median survival for all fifteen dogs was 172 days (mean survival = 316 days). The median survival for those dogs with splenic hemangiosarcoma was 145 days (mean survival = 271 days) as compared with previously published median survival times in dogs with splenic hemangiosarcoma treated with surgery alone of 19 to 65 days. Toxicities included neutropenia (11/15), severe gastroenteritis (4/15), cardiotoxicity (3/15), and sepsis (2/15). The authors conclude that vincristine, doxorubicin, and cyclophosphamide chemotherapy may be an efficacious treatment modality in dogs with hemangiosarcoma and is associated with acceptable toxicity.

Animals↗

Treatment of tumor-bearing dogs with actinomycin D.

Fifty dogs with advanced malignancies were treated with actinomycin D at doses ranging from 0.5 to 1.1 mg/m2 every 3 weeks. The greatest number of responses was noted in dogs with lymphoma, including dogs that had received prior chemotherapy. Other responding tumor types included anal sac adenocarcinoma, perianal adenocarcinoma, squamous cell carcinoma, thyroid carcinoma, and transitional cell carcinoma. The median time to maximum response for dogs with lymphoma was 7 days, with a median duration of 42 days. Gastrointestinal toxicity was the most frequently observed side effect. A dose of 0.6 to 0.7 mg/m2 appears to be appropriate for treating various malignancies in dogs.

Animals↗

Unexpected neurotoxicity in dogs receiving a cyclophosphamide, dactinomycin, and 5-fluorouracil chemotherapy protocol.

An inexpensive combination chemotherapy protocol containing cyclophosphamide, dactinomycin, and 5-fluorouracil was evaluated in dogs with carcinomas. Fifteen dogs were entered in this study, and there were 1 complete response and 2 partial responses among 12 evaluable dogs. However, 6 of 15 dogs (40%) developed neurotoxicity. The neurotoxicity of this protocol was compared with a previous 5-fluorouracil-containing protocol and found to be significantly higher. Due to the unacceptably high rate of neurotoxicity, this protocol cannot be recommended for use in dogs with cancer.

Animals↗

Cutaneous hemangiosarcoma in 25 dogs: a retrospective study.

Hemangiosarcomas confined to the skin and underlying muscle were surgically excised in 25 dogs. Tumors were staged based on their histological location (ie, dermal, hypodermal, and deep). Dermal (stage I) hemangiosarcomas were small, most commonly ventral-abdominal or prepucial in location, and were associated with prolonged survival times (median survival, 780 days). Tumors with hypodermal (stage II) and underlying muscular involvement (stage III) were grouped together because of their larger size, bruise-like appearance, lack of anatomic predilection, biological behavior, and shorter survival times (median survival of 172 and 307 days for dogs with stages II and III, respectively). We conclude that dermal hemangiosarcomas may be effectively treated with surgery alone, whereas hemangiosarcomas located within the hypodermal tissues bear a poor prognosis and warrant wide surgical excision with adjuvant chemotherapy.

Animals↗

Hemostatic disorders in cats: a retrospective study and review of the literature.

Hemostasis profiles from 101 cats presented for medical or surgical evaluation to The Ohio State University Veterinary Teaching Hospital from 1986 through 1991 were reviewed retrospectively; 69% were abnormal. Commonly identified abnormalities included a mixed hemostatic defect compatible with disseminated intravascular coagulation, thrombocytopenia, isolated prolongation of the activated partial thromboplastin time (APTT), and prolongation of both the APTT and one-stage prothrombin time. The most common disorders associated with abnormal hemostasis profiles in this study were liver disease, neoplasia, and feline infectious peritonitis.

Animals↗

Myeloid and megakaryocytic hypoplasia in related standardbreds.

Myeloid and megakaryocytic bone marrow hypoplasia in association with moderate to profound neutropenia was observed in 8 young Standardbred horses sired by the same stallion; 7 horses were intermittently thrombocytopenic. Evaluation of serial neutrophil counts in 2 horses suggested that a cyclic variation in neutrophil numbers was present, that lymphocyte numbers increased when neutrophil counts decreased, and that platelet counts decreased when neutrophil counts decreased. Preliminary bone marrow cultures indicated that myeloid progenitor cells were present and that these cells were able to respond to exogenous growth factors by differentiating. A bone marrow microenvironment or growth factor defect is suspected. Seven of 8 horses died or were euthanized. One horse with moderate neutropenia and a normal platelet count has been racing for 3 years. Necropsies in 4 horses did not reveal a cause for the myeloid hypoplasia. A familial basis for the disease is suspected.

Anemia, Aplastic↗

Vincristine impairs platelet aggregation in dogs with lymphoma.

Platelet aggregation before and after administration of 0.5 mg/m2 of vincristine (VCR) was evaluated in 7 dogs with spontaneously occuring lymphoma. Aggregation on platelet-rich plasma separated from blood collected in 3.8% sodium citrate was performed using adenosine diphosphate (ADP), arachidonic acid (AA), and collagen (COL) as agonists. The slope for aggregation in response to ADP was significantly lower after administration of VCR (P = .032). Maximal aggregation after administration of VCR was significantly lower in response to ADP, COL, and AA (P = .03, P = .04, and P = .03, respectively).

Adenosine Diphosphate↗

Clinical evaluation of methoximorpholino-doxorubicin (FCE 23762) in dogs with spontaneous malignancies.

We conducted a clinical evaluation of FCE 23762, a methoxymorpholino analog of doxorubicin, in 48 dogs with metastatic, nonresectable, or chemotherapy-resistant spontaneous malignancies at an initial dosage of 50-60 microg/kg IV every 3 weeks. Clinical evidence of toxicity was minimal; 6 dogs developed grades I, II, and III hematologic toxicities after the 1st treatment, and 1 dog developed grade II gastrointestinal toxicity. One dog became pancytopenic 4 months after discontinuation of FCE 23762. No other adverse effects were noted. Partial or complete remissions were observed in 32% of the dogs. Responses were observed both in previously untreated dogs and in those that had received prior chemotherapy, including doxorubicin. FCE 23762 is a promising new antineoplastic agent that can be used safely in dogs with cancer; doses higher than those used in this study may be used eventually in practice.

Animals↗