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Biomedical subjects

B F Feldman

Publications and source records attributed to B F Feldman.

At least 19 recordsLinked to original sources
PubMed1992

An evaluation of the effect of reagent modification on routine laboratory coagulation tests.

The purpose of this study was to evaluate the effect of modifying commercial reagents for the laboratory evaluation of several haemostatic parameters in normal, non-pregnant mares. The routine coagulation screening assays, namely, the activated partial thromboplastin time (APTT) and the one-stage prothrombin time (PT), and the specific coagulation assays for the determination of the biological activity of Factors VII, VIII:C and IX, are discussed.

Animals↗
PubMed1992

Evaluation of the haemostatic profile in the pre- and post parturient mare, with particular focus on the perinatal period.

Various haemostatic analytes were systematically evaluated for four months pre-partum and five months post partum in 14 healthy mares. The plasma fibrinogen concentration and both Factor VIII:C and von Willebrand factor activity showed gradual increases from mid-gestation and reached maximal, or near maximal activity at parturition. These increases were paralleled by an increase in plasma fibronectin concentration, the appearance of fibrinogen degradation products, and a modest rise in antithrombin III concentration. In contrast, the activity of Factor VII and Factor IX, and the one-stage prothrombin (PT) time and the activated partial thromboplastin (APTT) time remained relatively constant throughout the pre- and post parturient period.

Animals↗
PubMed1992

Hemostatic defects associated with two infusion rates of dextran 70 in dogs.

We investigated changes in hemostatic function after infusion of 6% dextran 70 (high molecular weight dextran) at 2 rates. Six healthy dogs underwent 3 regimens: 20 ml of dextran/kg of body weight administered in 1 hour (trial A), 20 ml of dextran/kg administered in 30 minutes (trial B), and 0.9% sodium chloride solution as a control administered over 1 hour to achieve hemodilution equivalent to that for 20 ml of dextran/kg (trial C). Before and at 2, 4, 8, and 24 hours after the start of trials A and B, we measured PCV, total solids (TS) concentration, amount of von Willebrand factor antigen (vWf:Ag), factor VIII coagulant activity (VIII:C), prothrombin time, activated partial thromboplastin time (APTT), platelet retention in a glass bead column, and buccal mucosa bleeding time (BMBT). Values were not obtained at 8 and 24 hours for trial C. Saline-induced changes in hemostasis were significant (P less than 0.05) from baseline throughout the sample collection period. Significant differences (P less than 0.05) between trial A and control were observed for vWf:Ag, VIII:C, BMBT, APTT, TS, and PCV values at 2 hours, and for VIII:C at 4 hours. Significant differences (P less than 0.05) between trial B and control were observed for APTT, TS, and PCV values at 2 hours, and for vWf:Ag, VIII:C, BMBT, APTT, TS, and PCV values at 4 hours. During trials A and B, mean values of analytes infrequently deviated from reference intervals, and clinical signs of bleeding were not observed in any dog.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Evaluation of hemostatic defects secondary to vascular tumors in dogs: 11 cases (1983-1988).

Two populations of dogs with cutaneous hemangiomas and hemangiosarcomas were evaluated retrospectively. One population consisted of 96 dogs seen at the Veterinary Medical Teaching Hospital at the University of California, Davis. The second population consisted of 116 dogs that had skin biopsy specimens submitted to a private veterinary diagnostic laboratory for histologic diagnosis. Nine dogs from the teaching hospital and 2 dogs, from which samples had been submitted to the veterinary diagnostic laboratory, developed hemostatic defects in association with the tumors. Hemostatic defects included hemorrhage directly from the tumor, thrombocytopenia, hypofibrinogenemia, and findings associated with disseminated intravascular coagulation. Because bleeding during surgery can develop in animals with hemostatic defects, dogs with one or more tumors suspected of being vascular in origin should have platelet numbers and hemostatic analytes evaluated prior to surgery, especially if petechiae or ecchymoses are evident.

Anemia↗
PubMed1991

Cytologic, microbiologic, and biochemical analysis of bronchoalveolar lavage fluid obtained from 24 healthy cats.

Twenty-four healthy cats underwent bronchoscopy and bronchoalveolar lavage to determine the normal cytologic environment of the lower respiratory tract of cats. Initial screening to ensure the health of the study population included complete histories, physical examinations, thoracic radiography, CBC, serologic tests for feline leukemia virus, feline immunodeficiency virus, and occult heartworm, and sugar and Baermann fecal flotation. In 18 cats, protected catheter brush samples of airway secretions from the lavaged lung segment were taken for culture of aerobic and anaerobic bacteria and mycoplasma. Bronchial lavage fluid (5 sequential 10-ml aliquots of normal saline solution) was pooled and filtered with cotton gauze. The unspun sample was used for determination of a total nucleated cell count. Lavage fluid was cytocentrifuged and 500 cells/slide were scored for determination of the cellular differential. Activity of lactate dehydrogenase and concentrations of total protein and IgG within the supernatant were measured, and assays were performed to detect the presence of IgA and IgM. Complete histologic evaluation of the lavaged lung of each of 6 random-source cats was performed after differential cell counting revealed 18% eosinophils within bronchoalveolar lavage fluid recovered from this group. Alveolar macrophages were the predominant cells encountered; however, a quarter of all cells recovered were eosinophils. A significant relationship was not found between the abundance of eosinophils in the lavage fluid, and either isolation of aerobic bacteria, high total nucleated cell counts, total protein concentrations, or activity of lactate dehydrogenase. Histologic evaluation of the lungs of 5 of 6 random-source cats revealed normal lungs in 2 cats, and minimal abnormal change in 3 others. Evaluation of the lungs from 1 random source cat revealed acute, mild eosinophilic bronchiolitis. We conclude that large numbers of eosinophils may be retrieved from the bronchoalveolar lavage fluid of healthy cats.

Animals↗
PubMed1989

Thrombocytosis associated with a myeloproliferative disorder in a dog.

A dog with a myeloproliferative disorder and thrombocytosis had clinical signs that were consistent with a diagnosis of essential thrombocythemia. The dog was treated with aspirin, radioactive phosphorus, and melphalan. Eighteen months after referral, the disorder progressed to chronic granulocytic leukemia, and treatment was switched to hydroxyurea. Fourteen months later, the dog was euthanatized because of uncontrollable atrial fibrillation.

Animals↗
PubMed1988

Quantitative platelet disorders.

Thrombocytopenia may be caused by abnormal platelet production, accelerated removal owing to immunologic or nonimmunologic reasons, or sequestration of platelets in the spleen. Bleeding associated with thrombocytopenia usually presents as petechial or ecchymotic hemorrhages or epistaxis. Immunologic and nonimmunologic cases of thrombocytopenia may be diagnosed with routine hematology, bone marrow cytology, and platelet specific tests. Thrombocythemia may also be associated with platelet functional abnormalities, contrasting the normal platelet function noted in reactive thrombocytosis.

Animals↗
PubMed1988

Thrombocytopenia and drugs.

Thrombocytopenia is a relatively common side effect of drug therapy. The pathogenetic mechanisms of drug-induced thrombocytopenia are varied and sometimes poorly understood. Immunologic and other cytotoxic effects may result in decreased production and/or increased destruction of platelets. The pathogenesis of drug-induced thrombocytopenia is reviewed. Diagnosis and treatment are also discussed.

Animals↗
PubMed1988

Effect of equine ehrlichial colitis on the hemostatic system in ponies.

Hemostatic function was determined in 10 ponies at various times after inoculation with Ehrlichia risticii to determine whether equine ehrlichial colitis (EEC) caused changes in the hemostatic system and to determine the prognostic value of hemostatic function tests during EEC. Mean platelet count; plasma fibrinogen, fibronectin, factor VIII: coagulant, alpha 2-antiplasmin, and plasminogen values; and serum concentrations of fibrin/fibrinogen degradation products changed significantly (P less than 0.05) from base line (day 0, before inoculation) during 18 days after inoculation with E risticii. Four ponies that died or were euthanatized because of severe clinical signs of EEC had significantly (P less than 0.05) greater mean plasma fibrinogen concentrations plasma factor VIII:coagulant values, and activated partial thromboplastin times immediately before death than did the 6 surviving ponies. Factor V concentrations were significantly (P less than 0.05) lower on postinoculation days 10 and 20 in nonsurvivors. Seemingly, changes in hemostasis took place during EEC. Ponies that did not survive EEC had greater laboratory evidence of coagulopathy.

Animals↗
PubMed1988

A turbidimetric method for fibronectin assay in the dog.

An immunoturbidimetric method, using spectrophotometry, for the assay of canine plasma fibronectin concentration was compared with the immunoelectrophoretic method. The spectrophotometric method (S) correlated positively (r = 0.7) and significantly (P less than 0.01) with the immunoelectrophoretic method (I). The regression equation was S = 0.37I + 53. Ninety-five percent confidence levels for the regression line were calculated to allow detection, by spectrophotometry, of plasma fibronectin concentrations outside the normal range.

Animals↗
PubMed1988

Plasma fibronectin concentration associated with various types of canine neoplasia.

Fibronectin, a large glycoprotein found in soluble form in plasma and in insoluble form in connective tissue matrices, has been implicated in cell-to-cell and cell-to-substratum interactions, inflammation and tissue repair, phagocytosis, hemostasis, and oncogenic cell transformation. Because fibronectin concentration is diminished or lacking on cell surfaces of many transformed cell lines and because decreased concentration of plasma fibronectin is associated with suboptimal mononuclear phagocyte system function and host defense, plasma fibronectin concentration was evaluated in 119 dogs with various forms of neoplasia. Included were 43 dogs with neoplasia of the skin and soft tissue, 18 with gastrointestinal tract neoplasia, 29 with mammary gland neoplasia, and 29 with various other types of neoplasia. Of the dogs studied, 44 (37%) had evidence of metastatic disease. This group had fibronectin concentration that differed significantly (P less than 0.01) from the plasma fibronectin concentration reference interval. Within this group, 9 dogs (20% of this group) had plasma fibronectin values within the reference interval, 33 (75%) had significantly (P less than 0.01) lower values than the reference interval, and 2 (5%) had significantly (P less than 0.01) higher values than the reference interval. These data suggested that fibronectin concentration determination, when results are abnormal, may be of diagnostic and prognostic interest.

Animals↗
PubMed1987

Scanning electron microscope study of platelet release by canine megakaryocytes in vitro.

Megakaryocytes were isolated from bone marrow from healthy dogs, using a combination of density-gradient centrifugation and polysucrose-velocity sedimentation techniques. The 2-step separation technique resulted in a preparation comprising 30% to 35% megakaryocytes of total nucleated cells. Accessibility to large numbers of viable canine megakaryocytes allowed investigation of platelet release by these cells in short-term cultures. Megakaryocytes were observed to form long cytoplasmic processes that gradually developed segmental constrictions and subsequently fragmented into platelet-sized pieces. Some platelet-sized cytoplasmic pieces of megakaryocytes presumably underwent discoid transformation.

Animals↗
PubMed1987

Circulating proplatelets: isolation and quantitation in healthy rats and in rats with induced acute blood loss.

A technique to isolate megakaryocyte proplatelet processes from blood of rats' hearts, using colloidal silica coated with polyvinylpyrrolidone density gradient, was developed. The proplatelet concentration in blood from right ventricles was significantly higher (P less than 0.001) than that in blood from left ventricles in healthy rats, as well as in rats with induced acute blood loss. The proplatelet concentration of blood from the heart, 24 hours after acute blood loss was induced was significantly (P less than 0.001) increased, indicating that platelet production was accelerated. The demonstration of proplatelets entering the pulmonary circulation indicates platelet release via proplatelet formation. Seemingly, proplatelets are fragmented in the lungs at predesignated locations along the proplatelet process.

Acetylcholinesterase↗
PubMed1987

In vitro platelet release by rat megakaryocytes: effect of metabolic inhibitors and cytoskeletal disrupting agents.

Development of an in vitro visual assay facilitated the study of large numbers of megakaryocytes undergoing proplatelet formation in short-term cultures. Approximately 9% of megakaryocytes formed platelets during a 24-hour period. In the presence of an inhibitor of anaerobic glycolysis (NaF), proplatelet formation was inhibited, whereas inhibitors of respiration (NaCN) did not significantly (P greater than 0.05) decrease proplatelet formation. Presence of the microtubule-disrupting agents colchicine and vincristine sulfate in culture medium inhibited proplatelet formation, whereas the microfilament-disrupting agent cytochalasin B had a less pronounced inhibition.

Animals↗
PubMed1987

In vitro platelet release by rat megakaryocytes: effect of heterologous antiplatelet serum.

A visual assay to study megakaryocyte platelet release via proplatelet formation in vitro was established. Samples of megakaryocyte-enriched rat bone marrow were incubated (37 C) in RPMI-1640 medium with 15% autologous serum in specially prepared chambers. In the culture system, approximately 6% of megakaryocytes formed proplatelet processes within 24 hours. Inclusion of a heterologous antiplatelet antibody in the culture system inhibited proplatelet formation, compared with that in controls.

Animals↗