Retrievable, replaceable, macroencapsulated pancreatic islet xenografts. Long-term engraftment without immunosuppression.

Prevention of rejection and prolongation of graft survival are critical to achieving successful islet cell transplantation. Various techniques have been utilized to prolong graft survival. Recently, protection of pancreatic islets from host immune mechanisms by isolating the islets in artificial membranes has emerged as an attractive alternative to the use of immunosuppression. In this Rapid Communication, we describe a novel method for macroencapsulation of rat islets in hydrophilic macrobeads made with various combinations of agarose, collagen, and Gelfoam. Encapsulated xenotypic islets were placed intraperitoneally in mice in which diabetes was induced by streptozotocin. The encapsulated xenografts maintained normoglycemia > 170 days. Recipients mice had normal glucose tolerance tests, which indicates that the islets in the macrobeads were functioning as they would in an intact pancreas. Macrobeads retrieved up to 103 days after transplantation showed no evidence of tissue reaction or local inflammation. These retrieved macrobeads could also be retransplanted and replaced. Our studies indicate that the agarose-collagen/Gelfoam macrobeads we have developed serve both to protect islet xenografts from rejection and to provide a microenvironment in which the islets maintain and support their normal function in vivo. Because they may be retrieved after implantation and replaced, these macrobeads may be suitable for human clinical islet cell xenotransplantation.

Analysis of DNA aneuploidy and c-myc oncoprotein content of canine plasma cell tumors using flow cytometry.

To derive a method for determining malignant potential of plasma cell tumors, a retrospective analysis of the DNA ploidy and relative p62c-myc oncoprotein content using bivariate flow cytometry was performed on 23 formalin-fixed, paraffin-embedded tissues from 23 dogs. The samples included one tissue each from 17 males and six females 2 to 16 years of age (mean = 7.5 years). Twelve breeds were represented, including three Cocker Spaniels, three Golden Retrievers, and five of mixed breed. Ten of the samples were histologically classified as malignant-plasma cell tumors, and ten specimens were classified as benign. Three samples of plasmacytic inflammation, from two Cocker Spaniels and one Shih Tsu, were included as controls. The ploidy and relative c-myc content data obtained were compared with the histologic grade. A significant difference in ploidy was found between benign and malignant tumors (P < or = 0.05). Five of nine malignant plasma cell tumors were aneuploid; the remainder were diploid (4/9) or tetraploid (1/9). Only one of the benign plasmacytomas was aneuploid (1/10), whereas six were diploid (6/10), and three were tetraploid (3/10). All of the controls were diploid (3/32). When relative amounts of p62c-myc from malignant and benign tumors were compared by flow cytometry, a greater significant difference was established (P < or = 0.01) than bu using aneuploidy alone. Relative values of p62c-myc content ranged from 219 to 553 units in 8/10 malignant plasma cell tumors and from 86 to 392 units in 3/10 benign plasmacytomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphomas in dogs. A morphologic, immunologic, and clinical study.

One hundred seventy-six canine lymphomas were classified morphologically using four of the major human lymphoma classification schemes (Rappaport, Lukes-Collins, Kiel, and the Working Formulation). All 176 dogs received the same chemotherapeutic protocol. Sixty-two of these lymphomas had their immunophenotypes established by examination of cell surface markers by automated cytofluorography. Several different morphologic types of canine lymphoma were identified and these were comparable to morphologic categories in human classification schemes. Follicular and low grade lymphomas were rare. The two most common morphologic types were diffuse large cell (centroblastic) and immunoblastic. The Kiel classification appeared to be the most useful human scheme for classifying the canine lymphomas. Cytofluorographic analysis was generally straightforward, and 60 of the 62 lymphomas were placed into one of three immunophenotypic categories: 27 pan-T(LQ1)+SIg+, 21 pan-T(LQ1)-SIg+, and 12 pan-T(LQ1)+SIg-. Two of the lymphomas could not be characterized immunologically because a pre-existing or reactive non-neoplastic population of lymphocytes made interpretation of single cell suspension analysis difficult. The authors identified correlations between morphology and survival and disease-free remission; dogs with high-grade tumors generally survived the longest and had the longest remissions. No correlations were identified between high concentrations of serum lactate dehydrogenase, age, sex, or stage of disease, and morphology, immunophenotype, remission, or survival times. A significant correlation between clinical illness and survival time was documented. The median age of the dogs was nine years, no significant effect of sex on prevalence was observed, and some breeds were significantly overrepresented. Significant morphologic-immunophenotypic correlations included shorter remission and survival times for T-cell tumors than B-cell tumors, and a highly significant correlation between the pan-T(LQ1)+SIg-"T cell" phenotype and hypercalcemia.

Cutaneous plasmacytomas in dogs: a morphologic and immunohistochemical study.

Forty-nine cutaneous plasmacytomas in 46 dogs were studied. Tumors occurred at solitary sites in middle-aged to old dogs (mean age, 9.7 years) and most commonly involved the skin of the digits, lips, and ears. Initial diagnosis was made on the basis of light microscopic morphologic findings. Tumors were graded according to the extent of cellular differentiation and immunoreactivity to a panel of immunohistochemical markers (cytokeratins, canine IgG F[ab]2, neurofilament, neuron-specific enolase, S-100 protein, and vimentin). Immunoreactivity was limited to antibodies directed at canine IgG F(ab)2 and vimentin. Vimentin immunoreactivity was usually greater than that of canine IgG F(ab)2, but there was no correlation between immunoreactivity and histologic grade of the tumors. Thirty-six of 39 dogs (92.3%) followed (mean follow-up, 13 months) were cured by surgical excision. The results of this study indicate that canine cutaneous plasmacytomas are benign neoplasms that should be included in the differential diagnosis of cutaneous round cell tumors in dogs.

Methimazole treatment of 262 cats with hyperthyroidism.

The efficacy and safety of the antithyroid drug methimazole were evaluated over a 3-year period in 262 cats with hyperthyroidism. In 181 of the cats, methimazole was administered for 7 to 130 days (mean, 27.7 days) as a preoperative preparation for thyroidectomy. The remaining 81 cats were given methimazole for 30 to 1,000 days (mean, 228 days) as sole treatment for the hyperthyroid state. After 2 to 3 weeks of methimazole therapy (10 to 15 mg/d), the mean serum thyroxine (T4) concentration decreased significantly (P less than 0.001) from a pretreatment value of 12.1 micrograms/dl to 2.1 micrograms/dl. The final maintenance dose needed to maintain euthyroidism in the 81 cats that were given methimazole as sole treatment for hyperthyroidism ranged from 2.5 to 20 mg/d (mean, 11.9 mg/d). Clinical side effects developed in 48 (18.3%) cats (usually within the first month of therapy), which included anorexia, vomiting, lethargy, self-induced excoriation of the face and neck, bleeding diathesis, and icterus caused by hepatopathy. Mild hematologic abnormalities developed in 43 (16.4%) cats (usually within the first 2 months of treatment), which included eosinophilia, lymphocytosis, and slight leukopenia. In ten (3.8%) cats, more serious hematologic reactions developed including agranulocytosis and thrombocytopenia (associated with bleeding). These hematologic abnormalities resolved within 1 week after cessation of methimazole treatment. Immunologic abnormalities associated with methimazole treatment included the development of antinuclear antibodies in 52 of 238 (21.8%) cats tested and red cell autoantibodies (as evidenced by positive direct antiglobulin tests) in three of 160 (1.9%) cats tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-dependent induction of anti-native DNA antibodies in cats by propylthiouracil.

Cats receiving propylthiouracil (PTU) develop antinuclear antibodies (ANA) and an immune-mediated disease syndrome characterized by anorexia, lymphadenopathy, weight loss, and Coombs-positive hemolytic anemia. Investigation of the ANA specificity indicated that the predominant ANA activity consistent of anti-native DNA (nDNA) antibodies. The formation of anti-nDNA antibodies and immune-mediated disease syndrome appeared to be dose-dependent, even in cats in which a response had been induced on 4 prior occasions. These results supply further evidence that PTU-induced autoimmunity is not the result of a simple drug allergy. Rather, it appears that PTU induces a lupus-like syndrome, including the hallmark sign of systemic lupus erythematosus, anti-nDNA antibodies.

Hypoadrenocorticism in a family of Standard poodles.

Thirty-one ancestors of a Standard Poodle with hypoadrenocorticism were located. Hypoadrenocorticism had been confirmed in 8 of 32 dogs (25%) by use of ACTH response testing or necropsy. In 2 additional dogs, hypoadrenocorticism was diagnosed on the basis of characteristic clinical signs and serum electrolyte abnormalities consistent with adrenocortical insufficiency. Although an obvious pattern of inheritance was not evident, the high prevalence of hypoadrenocorticism suggested that heredity may have been a factor in the development of idiopathic adrenal insufficiency in dogs of this family.

Monoclonal antibodies directed at human T lymphocyte activation antigens cross react with concanavalin A-stimulated canine and baboon peripheral blood lymphocytes.

A panel of 10 monoclonal antibodies directed at activation antigens on human T lymphocytes were tested for cross reactivity with canine and baboon resting and ConA stimulated peripheral blood lymphocytes. Monoclonal antibodies anti-OKT19, anti-OKT-21, and anti-OKT22 labeled a high percentage of both resting and stimulated canine and baboon cells. Anti-OKT24 labeled activated but not resting baboon lymphocytes and did not label canine lymphocytes. Anti-HLA-DR labeled a small percentage of resting baboon lymphocytes (presumably B cells) and a high percentage of activated baboon and resting and activated canine lymphocytes. Anti-OKT14, anti-OKT20, and anti-OKT23 did not label canine or baboon lymphocytes. Anti-OKT9 did not label baboon lymphocytes, but labeled a low percentage of lymphocytes in one dog. Anti-TAC labeled activated but not resting canine and baboon cells.

Investigation of cross-reactivity between commercially available antibodies directed against human, mouse, and rat lymphocyte surface antigens and surface markers on canine cells.

Using automated flow cytometry, 23 commercially available antibodies (all but one of them monoclonal) raised against surface antigens of specific populations of human, rat, and mouse lymphocytes were tested for cross-reactivity to peripheral blood lymphocytes from five clinically healthy adult dogs. Of all the antibodies tested, only the polyclonal anti-asialo GM1 directed against mouse NK cells, and the monoclonal antibodies anti-HLA-DR directed against the human class II antigen and anti-B1, a human pan B cell marker, consistently labeled subpopulations of canine lymphocytes.

Use of plasmapheresis and chemotherapy for treatment of monoclonal gammopathy associated with Ehrlichia canis infection in a dog.

Monoclonal gammopathy associated with Ehrlichia canis infection was diagnosed in a German Shepherd Dog. The dog was treated by use of chemotherapy and tetracycline and by plasmapheresis. The dog tolerated plasmapheresis and long-term drug therapy well, and clinical signs resolved over a 90-day period. The monoclonal gammopathy resolved after treatment, but specific antibody to E canis indicated suppression followed by a rebound to the initial high titer.

IgA deficiency in shar-pei dogs.

Two shar-pei puppies examined because of signs of sinopulmonary disease, one of which also had skin disease, had deficient IgA concentrations. Deficient serum IgA concentrations also were confirmed in 30 of 39 (76.9%) clinically normal adult dogs in two colonies of shar-peis. Both courses of disease--sinopulmonary signs and chronic skin disease and a benign clinical course--have been reported in human patients with IgA deficiency. Thus, the shar-pei might be an appropriate model for studying the immunopathology of IgA deficiency in man.

Paranasal meningioma in the dog: a clinicopathologic study of ten cases.

Paranasal meningiomas were diagnosed in ten dogs based on gross and light microscopic examinations of tissue specimens, and, in one case, electron microscopic examination. Seven of ten dogs were female (average age was 13 years). Most dogs (7/10) had seizures on examination. Two dogs with meningioma located in the nasal cavity had nasal discharge, and one had epistaxis. Tumors originated in the nasoparanasal region (eight) and frontal region of the cranial cavity (two). The histologic types of meningioma included psammomatous (two), transitional (three), meningotheliomatous (two), fibroblastic (two), and angioblastic (one). Tumors were malignant and extended to the brain in eight cases. These tumors differed from intracranial meningiomas mainly in their more anaplastic nature and aggressive behavior.

Intracranial meningioma: a comparative pathologic study of 28 dogs.

Intracranial meningiomas were identified in 28 dogs based on histologic examination of tissue. The average age of the dogs was 11 years, and 83% (20/24) were 10 years old or older. German shepherd and mixed breed were most common (31% each, 8/26). Grossly, meningiomas were oval, dome-shaped and flattened masses adherent to the dura and compressing the brain. Forty-eight percent (15/26) of the tumors affected the dorsal surface of the brain, and two thirds of these were located in the anterior half. Histologically, tumor types were transitional (13), meningotheliomatous (11), angioblastic (three), and fibroblastic (one). There was direct invasion of the brain in 27% (6/22) although we observed neurologic signs and pathologic changes in 88% (23/26) and 90% (18/20) of the dogs, respectively. Intracranial meningioma can be compared and contrasted with this tumor in man and cats.

Prognostic factors for multiple myeloma in the dog.

Multiple myeloma was diagnosed in 60 dogs. Diagnosis was confirmed in each case by observation of greater than 5% plasma cells on examination of a bone marrow aspirate and detection of monoclonal gammopathy of immunoglobulin (Ig) A or IgG. Treatment with melphalan, cyclophosphamide, and prednisone was associated with long-term survival (median, 540 days). Response to therapy was significantly related to prognosis (P less than 0.01), whereas hypercalcemia and Ig light chain proteinuria (Bence Jones) were associated with shorter median survival times.

A clinicopathologic and ultrastructural study of undifferentiated malignant tumors of the oral cavity in dogs.

Undifferentiated malignant tumors of the oral cavity were diagnosed in six dogs under 2 years of age. The dogs were examined because of pain and swelling of the upper molar or premolar areas. In all six dogs, the tumors were initially misdiagnosed as infections or carnasal abscesses. The differential diagnosis included malignant lymphoma, osteosarcoma, mesenchymal chondrosarcoma, embryonal rhabdomyosarcoma, and malignant melanoma. Electron microscopy of three neoplasms showed that there were no specific features characteristic of carcinoma or sarcoma. Immunoperoxidase studies for cytokeratins, epithelial membrane antigen, actin, myosin, desmin, and vimentin were also negative. We conclude that these tumors be designated undifferentiated malignant tumors of the oral cavity until histogenesis is established.

Plasmapheresis in five dogs with systemic immune-mediated disease.

Five dogs with signs referable to systemic immune-mediated disease, four with systemic lupus erythematosus, and one with probable lupus myopathy were treated with plasmapheresis in combination with low-dose immunosuppressive drug therapy. Previous treatment with conventional dosages of prednisone was not satisfactory and was associated with adverse side effects. Two dogs had short-term responses to combined therapy, and 3 dogs had sustained responses. Clinical remission was associated with normalization of serum complement levels and decreases in antinuclear antibody titers. Toxicosis potentially related to plasma component depletion was observed in 2 dogs. Acute clinical illness and disease states refractory to conventional immunosuppressive therapy should be considered indications for plasmapheresis.

Propylthiouracil-induced immune-mediated disease in the cat.

An immune-mediated disease was produced in 9 of 17 (53%) normal healthy cats by daily p.o. administration of 150 mg of 6-propylthiouracil (PTU). This disease syndrome is characterized by lethargy, weight loss, lymphadenopathy, hemolytic anemia, a positive direct antiglobulin test (DAT) and antinuclear antibodies (ANA). The duration of drug administration before the development of a positive DAT and/or ANA ranged from 3 to 8 weeks (Mean +/- S.E.M. = 4.5 +/- 0.6), whereas the duration before the onset of clinical signs ranged from 4 to 8 weeks (6.1 +/- 0.6 weeks). On cessation of PTU administration, clinical signs resolved in all cats within 2 weeks, and the DAT and test for ANA were negative within 1 to 4 weeks (1.9 +/- 0.4 weeks). During nine PTU-rechallenge periods in four cats, both the mean time to develop a positive DAT and ANA (2.5 +/- 0.8 weeks) and the mean time to develop overt clinical signs (2.6 +/- 0.7 weeks) were shorter than similar mean times in the initial PTU treatment period (P less than .01). During nine episodes of PTU-induced disease in seven cats, PTU administration was discontinued and replaced with 150 mg of 6-propyluracil (PU), a nonsulfur analog of PTU. Resolution of both clinical and serologic signs of disease occurred in seven of the nine disease episodes within 1 to 3 weeks (2.1 +/- 0.4 weeks). In the two cats whose disease did not resolve on PU, one was sacrificed after 1 week of PU administration, without clinical or serologic resolution, because of the severity of the PTU-induced disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasmapheresis as adjuvant therapy for autoimmune hemolytic anemia in two dogs.

Severe, acute, autoimmune hemolytic anemia in 2 dogs was treated, using prednisone, cyclophosphamide, plasmapheresis, and blood transfusion. In 1 case, splenectomy was performed successfully after plasmapheresis and blood transfusion. Antibody removal by means of plasmapheresis effected short-term stabilization to severe hemolysis in both dogs, but was suspected to have contributed to the death of 1 dog.