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C G Couto

Publications and source records attributed to C G Couto.

At least 19 recordsLinked to original sources
PubMed2005

Morphologic characterization of specific granules in Greyhound eosinophils.

BACKGROUND: "Vacuolated" eosinophils (ie, eosinophils with empty, nonstaining granules) have been described previously in normal Greyhounds. However, to our knowledge, detailed studies of granules in vacuolated and normal eosinophils in this breed have not been performed. OBJECTIVE: The objective of this prospective study was to characterize some of the morphologic, ultrastructural, and cytochemical staining features of specific (primary) granules in both normal and vacuolated eosinophils in Greyhound blood. METHODS: Morphologic features of eosinophils in Wright's- and Diff-Quik-stained peripheral blood smears from 49 Greyhounds were compared with 200 blood smears from non-Greyhound dogs. Transmission electron microscopy was done on blood from 3 Greyhounds with vacuolated eosinophils and 3 with normal eosinophil granules. Blood smears from 4 of these dogs also were stained cytochemically with alkaline phosphatase (AP), chloracetate esterase (CAE), and alpha naphthyl butyrate esterase (ANBE). The morphologic features and tinctorial properties of vacuolated and normal eosinophils were compared. RESULTS: Twenty-six Greyhounds (53%) had vacuolated eosinophils and 23 (47%) had normal granulated eosinophils in smears stained with Wright's stain. Only 1% of eosinophils were vacuolated in non-Greyhound dogs. Twenty of the 23 (85%) Greyhounds with normal granulated eosinophils on Wright's-stained smears had vacuolated eosinophils in smears stained with Diff-Quik. Ultrastructurally, no morphologic differences were observed between granules of vacuolated and normal eosinophils. Both vacuolated and normal eosinophils in Greyhounds were positive for AP and negative for CAE and ANBE, as expected for normal dogs. CONCLUSION: Vacuolated eosinophils in Greyhounds likely reflect, at least in part, differential staining properties of the specific granules with different hematologic stains. Ultrastuctural and cytochemical features of eosinophil granules were similar in normal and vacuolated eosinophils from Greyhounds.

Animals↗
PubMed2001

Effect of storage conditions on hemostatic parameters of canine plasma obtained for transfusion.

OBJECTIVE: To evaluate the effects of various storage conditions on one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), and fibrinogen concentration of canine plasma collected for transfusion. SAMPLE POPULATION: Plasma from 9 dogs. PROCEDURE: Whole blood was collected from dogs by means of jugular venipuncture and centrifuged at 7,300 X g for 20 minutes at 0 C. A plasma extractor was then used to generate plasma. Aliquots of plasma were collected in segments of plastic tubing and in microcentrifuge tubes, and plasma collection bags, tubing segments, and microcentrifuge tubes were immediately frozen at -30 C. Additional tubing segments and microcentrifuge tubes were stored at 2 C. After 1 week of storage, all samples were thawed, and OSPT, APTT, and fibrinogen concentration were measured. Collection bags and microcentrifuge tubes were refrozen at -30 C, and values were measured again 30 days after blood collection. RESULTS: Values for OSPT, APTT, and fibrinogen concentration did not vary significantly with storage time, temperature, or container. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that storage for up to 30 days and at 2 C versus -30 C did not have any significant effect on hemostatic parameters of canine plasma obtained for transfusion.

Animals↗
PubMed2000

The histologic classification of 602 cases of feline lymphoproliferative disease using the National Cancer Institute working formulation.

Case information and histologic slides for 688 admissions of feline tissues from 12 veterinary institutions were assembled and reviewed to determine tissues obtained by biopsy or necropsy, age and sex of cat, tumor topography, feline leukemia viral antigen status, histologic frequency of mitoses, diagnosis, presence of necrosis, and presence and degree of sclerosis. Histologic sections were examined to place the lesions in one of the diagnostic categories of the National Cancer Institute working formulation (NCI WF) for lymphomas or lymphoid leukemia. Correlations between the various factors determined were tested using contingency tables and chi-square analysis to provide a statistical comparison between the levels of observations determined by case examination with the numbers expected from chance alone. Significant correlations (P < or = 0.05) were found between diagnosis and tumor topography, the frequency of mitoses, necrosis, sclerosis, and age, between mitoses and necrosis, topography, age, and feline leukemia viral infection status, between topography and necrosis and age, and between leukemia viral status and age. Significant correlations between diagnosis and tumor topography included a greater than expected number of cases of acute and chronic lymphoid leukemia and multicentric distribution of tumor. Small cell lymphomas were more frequent than expected in enteric and cutaneous areas and less frequent than expected in mediastinal, renal, and multicentric areas. In contrast, the high-grade small noncleaved type of lymphomas was found significantly more frequently than expected in the mediastinum and less frequently than expected in enteric tissues. In comparing diagnosis and frequency of mitoses, the lymphomas classified as low grade by the NCI WF were significantly more frequent than expected in the lower categories (0-2/100x) of mitoses, and those classified as high-grade lymphomas were more frequent than expected in the higher categories (4-8/1OOx) of mitoses. In comparing diagnosis and sclerosis, diffuse sclerosis was more frequent than expected for the intermediate grade lymphomas of mixed cell type and for the high-grade lymphomas of the immunoblastic polymorphous type. In comparing diagnosis and locally extensive necrosis, this feature was more frequently observed than expected for cases of intermediate grade lymphoma of the small-cleaved cell category and for the high-grade lymphoma of the immunoblastic cell type. In comparing mitoses and necrosis, the lower grade lymphomas were, in general, characterized by a lower frequency of mitoses and a lower incidence of necrosis then would be expected from chance alone. In contrast, the higher grade lymphomas were characterized by more frequent mitoses and a higher incidence of necrosis. In tests comparing mitoses and tumor topography, lymphomas of the alimentary tract were more frequently observed than expected in the category with the lowest level of mitoses (0-1/100x), whereas lymphomas of the mediastinum and kidney were more frequently observed than expected in the categories with a higher level (4-20/ 100x) of mitoses.

Animals↗
PubMed2000

Acute lymphoblastic leukemia in a juvenile southern black rhinoceros (Diceros bicornis minor).

A 21-mo-old female southern black rhinoceros (Diceros bicornis minor) developed acute upper respiratory dyspnea in association with lymphadenopathy and marked immature lymphocytosis. A diagnosis of acute lymphoblastic leukemia was reached on the basis of the morphologic and cytochemical characteristics of peripheral lymphoblasts. Antineoplastic chemotherapy included administration of cytarabine, cyclophosphamide, vincristine, and doxorubicin, with clinical remission achieved 19 days after initiation of treatment. The rhinoceros died, however, of congestive heart failure, presumably secondary to doxorubicin cardiotoxicity and a particular sensitivity of rhinoceros myocardial tissue to free hydroxyl radicals. The pharmacologic effects of any therapeutic agent need to be carefully considered before use in the black rhinoceros, especially within the context of the unique physiology of this species.

Animals↗
PubMed1998

Mutation of the p53 tumor suppressor gene in spontaneously occurring osteosarcomas of the dog.

Inactivation of the p53 tumor suppressor gene has been implicated in the pathogenesis of numerous human cancers, including osteosarcomas. Appendicular osteosarcomas of the dog appear to be a good model for their human equivalent with regard to biologic behavior, epidemiology and histopathology. We individually screened exons 5-8 of the p53 gene for mutations in 15 canine appendicular osteosarcomas using 'Cold' SSCP to compare the role of this gene in human and canine osteosarcoma tumorigenesis. Seven of the tumors (47%) exhibited point mutations, with one tumor possessing two mutations within different exons. Of these, seven were missense mutations and the eighth was a 'silent' mutation potentially affecting the exon 6-7 splicing region. Five of the missense mutations were located in highly conserved regions IV and V, while another corresponded with the highly conserved codon 220 mutational hotspot located outside the conserved domains. The locations and types of mutations were nearly identical to those reported in human cancer. These findings provide strong evidence of the involvement of p53 mutations in the development of canine appendicular osteosarcomas. Canine osteosarcomas appear to be a promising model for their human equivalent on a clinical, pathologic, and molecular level.

Animals↗
PubMed1997

Overexpression of p53 tumor suppressor protein in spontaneously arising neoplasms of dogs.

OBJECTIVE: To determine prevalence of p53 tumor suppressor protein overexpression in spontaneously arising tumors of dogs, using the CM-1 polyclonal antibody and immunohistochemical methods. DESIGN AND SAMPLE POPULATION: Retrospective analysis was performed on archived, paraffin-embedded tumor tissue from dogs. A total of 226 tumors were evaluated, including tumors of epithelial, mesenchymal, and round cell origins. PROCEDURES: Overexpression of p53 was detected by indirect immunohistochemical methods, using the CM-1 rabbit anti-human p53 polyclonal primary antibody. Protein overexpression was determined by use of a grading system based on percentage of stained tumor nuclei. RESULTS: Nuclear overexpression of p53 was detected in most squamous cell carcinomas, nasal adenocarcinomas, and perianal gland adenocarcinomas. Hemangiopericytomas, transitional cell carcinomas, mammary adenocarcinomas, apocrine gland adenocarcinomas, intestinal adenocarcinomas, mast cell tumors, and cutaneous histiocytomas had low numbers of nuclei overexpressing p53. Remaining tumor types had intermediate p53 nuclear overexpression. Cytoplasmic staining was observed in some carcinomas, particularly intestinal adenocarcinomas. CONCLUSIONS: Overexpression of p53 is common in spontaneously arising neoplasms of dogs. CLINICAL RELEVANCE: Prospective determination of p53 status in some tumor types may be as clinically useful in determining prognosis and predicting survival times for dogs with cancer as it is for human beings with cancer.

Animals↗
PubMed1996

p53 tumor suppressor protein overexpression in osteogenic tumors of dogs.

Alterations in the p53 tumor suppressor gene have been implicated in the genesis and/or progression of the majority of human cancers, including osteosarcoma. Stabilization of the protein by mutation or interaction with other proteins prolongs its half-life, rendering it detectable by immunohistochemistry. Osteosarcoma is the most common primary canine bone tumor and is characterized by frequent early metastases. Multilobular tumors of bone involve primarily flat bones of the head and are low-grade malignancies with lower metastatic potential. The objectives of this study were to determine the prevalence of p53 protein overexpression in 106 osteogenic tumors of dogs using an indirect immunohistochemical method and to compare p53 overexpression between tumors with different clinical behavior. A polyclonal p53 antibody (CM-1) served as the primary antibody. Tumors were scored based upon an estimate of the percentage of tumor cells stained. Significant differences in the prevalence of overexpression were observed between osteosarcomas (72%) and multilobular tumors of bone (20%, P = 0.0020). Osteosarcomas of the appendicular skeleton had a significantly higher prevalence of p53 overexpression (84%) than did osteosarcomas of the axial skeleton (56%, P = 0.0060). Our results show that p53 tumor suppressor protein is overexpressed in the majority of canine osteosarcomas. The higher prevalence of overexpression in osteosarcomas versus multilobular tumors of bone and in osteosarcomas of the appendicular skeleton versus those of the axial skeleton suggests that alterations in p53 expression correlate with highly aggressive tumor behavior.

Animals↗
PubMed1996

Lymphangiosarcoma in a young dog.

Lymphangiosarcoma was diagnosed from biopsy material obtained from an 8-week-old puppy with a progressively enlarging subcutaneous inguinal swelling. Histologically, the tumor was composed of endothelial cells immediately adjacent to large collagen bundles. Tumor cells formed irregular vascular channels which extended along the connective tissue investments of small vessels and nerves of the subcutis and deep dermis. Similar neoplastic tissue extensively infiltrated an inguinal lymph node. Neoplastic cells were immunohistochemically stained for factor 8-related antigen and were weakly positive when compared with several hemangiomas and hemangiosarcomas. Transmission electron microscopy revealed numerous micropinocytotic vesicles and a continuous basal lamina. The puppy was euthanatized at 8 months of age due to severe septic polyarthritis. Lymphangiosarcoma was documented at the site of the original tumor as well as in the axillary lymph node at necropsy.

Animals↗
PubMed1995

Systemic Mycobacterium smegmatis infection in a dog.

A 3-year-old female Basset Hound was examined because of fever and lameness of 2 months' duration. Physical examination revealed a small cranial abdominal mass, which had an ultrasonographic appearance of a large abdominal lymph node. Cytologic examination of an ultrasound-guided fine-needle aspirate of the mass revealed a few macrophages that contained numerous linear unstained structures consistent with mycobacteria. Intracellular acid-fast bacilli were identified in an aspirate that was stained with modified Ziehl-Neelsen. Exploratory laparotomy revealed wide-spread abdominal lymphadenopathy. Histologic examination of hepatic and lymph node biopsy specimens revealed chronic granulomatous hepatitis and lymphadenitis. Acid-fast organisms isolated after bacteriologic culturing of a mesenteric lymph node specimen were identified as Mycobacterium smegmatis. Because the prognosis was poor, the dog was euthanatized.

Animals↗
PubMed1995

Systemic and colonic venous hemostatic alterations in horses during low-flow ischemia and reperfusion of the large colon.

Twenty-four horses were randomly allocated to 3 groups. All horses underwent a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls, group-2 horses underwent 6 hours of colonic ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline blood samples were collected, then low-flow colonic ischemia was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. All horses were monitored for 6 hours. Citrated systemic venous (SV) blood samples were collected from the main pulmonary artery, and colonic venous (CV) samples were collected from the colonic vein draining the ventral colon. Samples were collected at 0, and 2, 3, 3.25, 4, and 6 hours for determination of one-stage prothrombin time, activated partial thromboplastin time, antithrombin III activity, and fibrinogen concentration. Data were analyzed statistically, using two-way ANOVA for repeated measures, and post-hoc comparisons were made by use of Student Newman Keul's test. Statistical significance was set at P < 0.05. There were significant decreases in all hemostatic variables by 2 hours in SV and CV samples from horses of all 3 groups, but there were no differences among the 3 groups for any of these variables. These hemostatic alterations could have been secondary to a hypercoagulable state or to fluid therapy-induced hemodilution. Colonic ischemia-reperfusion was not the cause of these alterations because these alterations also were observed in the sham-operated control horses. Significant temporal alterations existed even after accounting for the hemodilution.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Evaluation of oncofetal protein-related mRNA transport activity as a potential early cancer marker in dogs with malignant neoplasms.

A 55-kd protein with mRNA transport activity found in fetal rat liver cells and plasma from mice, rats, and human beings with malignant neoplasms has been designated oncofetal protein 55 (OFP55). Monoclonal antibody produced to rat OFP55 cross-reacts with human OFP55. Using this monoclonal antibody in a bioassay measuring mRNA transport stimulated by OFP55, we tested the plasma from 19 dogs with a variety of malignant neoplasms, including carcinomas, sarcomas, lymphomas, and melanomas, and compared the results with plasma from 20 clinically normal dogs without evidence of neoplasia. The mean mRNA transport activity from the group of dogs with malignant neoplasms was 0.43 +/- 0.28%/mg of protein. Mean transport activity from the group of control dogs was 0.04 +/- 0.02%/mg of protein. These means were significantly different (P < 0.0001). The degree of overlap between these 2 groups in their OFP55-related mRNA transport activity was minimal, and measurement of this protein appears to have potential for the early detection of malignant neoplasms in dogs.

Animals↗
PubMed1992

Acute sterile hemorrhagic cystitis after a single intravenous administration of cyclophosphamide in three dogs.

Three dogs receiving cyclophosphamide IV as part of a combination chemotherapeutic regimen developed macrohematuria, stranguria, and pollakiuria within 24 hours of administration of the first dose of this drug. An 11-year-old spayed mixed-breed dog with an oral squamous cell carcinoma was administered 250 mg of cyclophosphamide/m2 of body surface, whereas a 4-year-old castrated male Gordon Setter was treated with 100 mg of cyclophosphamide/m2 and a 6-year-old male German Shepherd Dog with a cutaneous hemangiosarcoma was administered 140 mg of cyclophosphamide/m2. Aerobic bacterial culture, antimicrobial susceptibility testing, and urinalysis were performed on urine obtained by cystocentesis from all 3 dogs after hematuria was observed. Sterile hemorrhagic cystitis was diagnosed on the basis of large numbers of RBC in the urine, lack of pathogens on bacterial culturing of urine, and clinical signs. Although cyclophosphamide-induced cystitis in dogs has been reported in the literature numerous times, acute episodes developing within 24 hours of administration of the first dose have not been reported in this species with the use of therapeutic doses. Therefore, appropriate precautionary steps should be taken, even when the drug is being administered intermittently.

Animals↗
PubMed1992

Effects of mithramycin on calcium metabolism and bone in dogs.

Mithramycin (0.1 mg/kg) was administered intravenously to eight Beagle dogs on days 0 and 7 to determine its effects on calcium and phosphorus metabolism, serum parathyroid hormone concentration, osteoclastic bone resorption, and serum biochemical and hematologic parameters. Ionized calcium concentration was paradoxically increased on day 1 and decreased on day 8 in association with an increased serum parathyroid hormone concentration. Serum phosphorus concentration was decreased on days 1 and 2. Osteoclastic bone resorption in iliac cancellous bone was significantly decreased on day 8. There were mild increases in serum alkaline phosphatase (days 1, 2, 4, 8, 9), aspartate aminotransferase (day 9), and gammaglutamyl transpeptidase (days 7, 9) activities. Platelet numbers were increased on days 7 through 13, and packed red blood cell volumes were mildly decreased. This investigation demonstrates that two doses of mithramycin can be administered safely to dogs and may inhibit bone resorption in diseases associated with increased osteoclastic bone resorption, such as humoral hypercalcemia of malignancy.

Animals↗
PubMed1992

Correlation of DNA ploidy to tumor histologic grade, clinical variables, and survival in dogs with mast cell tumors.

By using flow cytometry, a retrospective analysis of the DNA content of 40 primary canine mast cell tumors and seven lymph nodes that contained metastatic mast cell tumor from 44 dogs of various breed, sex, and age was performed on formalin-fixed, paraffin-embedded samples of the tumors and nodes. These samples were chosen according to the following criteria: samples contained sufficient well-preserved tumor tissue in the paraffin block for processing, sufficient patient history data were available, clean and homogeneous cell suspensions were obtained after processing, and interpretable DNA histograms were produced on analysis. The ploidy data obtained were compared with the histopathologic grade, the anatomical site of occurrence, the clinical stage of the tumors, and the survival of the dogs. Over 70% (29/40) of the mast cell tumors were diploid. Three metastatic mast cell tumors in lymph nodes had the same ploidy status as their corresponding primary tumors. In five dogs, mast cell tumors from multiple sites in each dog displayed similar ploidy status. Of 26 dogs evaluated for survival times, 69% (18/26) had diploid tumors and 31% (8/26) had aneuploid tumors. When numbers of diploid versus aneuploid tumors were compared, no significant difference was found between any two grades, clinical stages, or anatomic sites. A significant difference (P = 0.02) was found, however, between aneuploid and diploid tumors when comparing Stage I and non-Stage I disease. The Kaplan-Meier survival plot indicated a tendency towards an increased survival within the first year in dogs with diploid versus aneuploid tumors (P = 0.06).

Animals↗
PubMed1992

Parathyroid hormone (PTH)-related protein, PTH, and 1,25-dihydroxyvitamin D in dogs with cancer-associated hypercalcemia.

Circulating N-terminal PTH-related protein (PTHrP), N-terminal PTH, and 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations were measured in normal dogs and dogs with cancer-associated hypercalcemia (CAH), parathyroid adenomas, and miscellaneous tumors. PTHrP was undetectable (less than 1.8 pM) in normal dogs and increased in dogs with CAH due to adenocarcinomas derived from apocrine glands of the anal sac (44.9 +/- 27 pM), lymphoma (8.3 +/- 4.4 pM), and miscellaneous carcinomas (13.3 +/- 11.4 pM). The PTHrP concentration decreased in dogs with lymphoma and anal sac adenocarcinomas after successful treatment of CAH. The PTHrP concentration had a significant linear correlation with total serum calcium in dogs with anal sac adenocarcinomas and hypercalcemia, but not in dogs with lymphoma and hypercalcemia. Serum N-terminal PTH concentrations were usually in the normal range (12-34 pg/ml) for all groups of dogs except dogs with parathyroid adenomas (83 +/- 38 pg/ml). The serum PTH concentration increased after successful treatment of CAH. Serum 1,25-(OH)2D concentrations were decreased, normal, or increased in dogs with CAH, and 1,25-(OH)2D levels decreased after treatment of CAH. In summary, circulating concentrations of PTHrP are consistently increased in dogs with CAH, and PTHrP appears to play an important role in the induction of hypercalcemia.

Adenoma↗