PubMed Health⌕ Search

Biomedical subjects

R B Epstein

Publications and source records attributed to R B Epstein.

At least 19 recordsLinked to original sources
PubMed1992

Thrombocytopoiesis in normal and sublethally irradiated dogs: response to human interleukin-6.

The response of megakaryocytes and platelets to the administration of recombinant human interleukin-6 (IL-6) was investigated in normal and sublethally irradiated dogs. IL-6 was administered for 2 weeks at doses of 10 to 160 micrograms/kg/d to normal animals to assess dose-response and toxicity. Subsequently, 40, 80, or 160 micrograms/kg/d for 2 weeks was administered to animals treated with 200 cG total body irradiation. Analysis of normal dogs showed a significant increment in the platelet count detectable approximately 11 days after initiation of IL-6 at all administered doses. Large platelets greater than 6.3 microns in diameter were observed 1 day after beginning IL-6, progressively increasing to as many as 19.1% of the total circulating platelets by day 10. The ploidy distribution of the marrow megakaryocytes did not differ from the normal at doses of less than or equal to 80 micrograms/kg/d, but at 160 micrograms/kg/d, a shift toward higher ploidy cells was noted. No change in total white count was noted; however, a decrease in hematocrit was seen at all doses. In the irradiated animals, the platelet count recovered earlier in the IL-6-treated dogs than in the controls, but no consistent change in the ploidy distribution was observed irrespective of dose. Large platelets were also noted in the treated animals, comprising up to 6.9% of the total platelet count. Fibrinogen levels were elevated to greater than 4 times normal. A significant decrease in hematocrit was seen in all animals, while no consistent change was noted in the white count. Elevations in serum cholesterol, triglycerides, and alkaline phosphatase, together with a decline in serum albumin were observed in all the treated animals (both normal and irradiated), but clinical symptoms were observed only in the dogs receiving greater than or equal to 80 micrograms/kg/d. The data show that IL-6 alone is capable of enhancing platelet recovery in dogs with bone marrow suppression.

Animals↗
PubMed1992

A canine model for hepatic venoocclusive disease.

Hepatic venoocclusive disease is a frequent lethal complication of bone marrow transplantation. It has also been associated with hepatic irradiation and administration of chemotherapeutic agents without BMT. The pathogenesis and therapy of VOD are unclear. The present studies were directed at developing a canine model for VOD. Three groups of dogs were studied. Group one consisted of 8 dogs in which monocrotaline (MC) was administered at 125 mg/kg orally on an intermittent schedule. In 7 of the 8 dogs 6 to 9 doses of drug were administered between 42 and 110 days. Group 2 consisted of 6 dogs receiving busulfan 2 mg/kg/day for 17-25 days, when platelet counts decreased to less than 5 x 10(4)/mm3 or clinical bleeding occurred. Group 3 consisted of 2 dogs receiving 24 Gy and 4 dogs receiving 36 Gy of whole-liver irradiation. Seven of 8 dogs in group 1 developed significant liver function abnormalities and evidence of portal hypertension. Histologic findings of VOD were present at autopsy. Group 2 dogs failed to develop clinical or laboratory liver abnormalities, but 3 of 6 animals had minimal histologic evidence of VOD. Three of 6 dogs in group 3 receiving 36 Gy developed hepatic dysfunction and had findings of fibrosis at autopsy. It was concluded that MC administration produced consistent clinical and histologic features of VOD in dogs. Changes occurring after busulfan or total-liver irradiation administration were less reproducible. Dogs are a suitable large-animal model for studies of VOD.

Animals↗
PubMed1979

The collection, preservation and function of peripheral blood hematopoietic cells in dogs.

Semicontinuous flow centrifugation (SFC) was employed in canines to obtain adequate numbers of cells for autologous marrow repopulation following supralethal cyclophosphamide administration (100 mg per kg). Four cycles using a 225 ml bowl and 30 ml per minute flow rate were carried out for procurement. Collections averaged 8.4 +/- 0.4 x 10(9) (n = 30) leukocytes. Mononuclear cells (MNC) comprised 75 +/- 2% of the population and granulocyte colony-forming units (CFU-C) totaled 1.9 +/- 0.09 x 10(5) colonies per collection. Eighty-six percent of mononuclear cells were "T" cells in the 30 to 90 second fraction compared to 49% at 150 to 120 seconds. CFU-C fractionation revealed a peak at 30-210 seconds and a second peak at 120-210 seconds. Following programed freezing and rapid thawing 77.7 +/- 11.4% of CFU-C were recovered. Using a dose of 1 x10(9) MNC per kg for reinfusion, marrow repopulation and clinical recovery occurred in four out of four dogs. It was concluded that 1) SFC was effective for obtaining adequate numbers of peripheral blood stem cells for autologous marrow repopulation. 2) A rapid thawing and direct transfusion technique appears satisfactory for administration. 3) Some separation of "T", "B" and CFU-C peripheral blood components is possible by centrifugation.

Animals↗
PubMed1979

Processing of peripheral blood stem cells for transplantation.

Canines were studied to determine the efficacy of peripheral blood collection by semicontinuous centrifugation to procure sufficient numbers of hematopoietic cells for marrow reconstitution. CFU-C assays on fresh and cryopreserved peripheral blood cells were compared to bone marrow aspirates. Attempts were made to partially separate hematopoietic cells from immunocompetent cells during buffy coat collection and by incubation with activated cyclophosphamide. Yields from 4 runs of semicontinuous centrifugation averaged 1.7 x 10(5) CFU-C compared to 1.9 x 10(5) CFU-C for standard marrow aspiration. Ratios of approximately 5/1 marrow to peripheral blood mononuclear cells (MNC) were found. Autologous transplantation with 1.6 x 10(4) CFU-C per kg resulted in evidence of marrow reconstitution within two weeks following otherwise lethal chemotherapy. Recovery of CFU-C following cryo-preservation was 82% for marrow and 78% for peripheral blood. Selective depression of MLC activity occurred when peripheral blood MNC were incubated for 30 minutes with activated cyclophosphamide. MLC was inhibited by greater than 90% while 70% of CFU-Cs were retained. It was concluded that peripheral blood may be a practical alternative to marrow for transplantation studies.

Animals↗
PubMed1979

Isolation and characterization of canine venereal tumor-associated inhibitory and blocking factors.

Spontaneous regression of the canine venereal tumor is associated with the production of a serum factor which inhibits in vitro tumor colony-forming units in agar. Logarithmic or persistent tumor growth, on the other hand, is characterized by a serum factor which protects cells against in vitro inhibition (blocking factor). These factors have been characterized by immunochemical methods. Whole regressor and blocking sera were fractionated by Sephadex G-200 filtration and immunoabsorption with rabbit antiserum specific for canine immunoglobulin G2a. Fractions were characterized by immunoelectrophoresis, radial immunodiffusion, and disc gel electrophoresis. In vitro inhibitory and blocking activity of the whole serum was accounted for by the purified immunoglobulin G2a. Blocking activity was also found in protein eluted from logarithmically growing tumors. Preparative polyacrylamide electrophoresis revealed five major fractions with blocking activity only in the immunoglobulin G fraction. Tumor eluates and immunoglobulin G isolated from serially removed tumors demonstrated with the clinical course of the tumor. Using ultrafiltration and sodium dodecyl sulfate electrophoresis of tumor-associated immunoglobulin G at low pH, it was not possible to identify an antigen complexed to the blocking antibody.

Animals↗
PubMed1978

Cytogenetic evidence for recurrence of acute myelogenous leukemia after allogeneic bone marrow transplantation in donor hematopoietic cells.

A 22-yr-old man with acute myelocytic leukemia received a bone marrow transplant from a genotypically HLA-identical female sibling after cyclophosphamide preparation. He remained in complete remission for 18 mo, when he developed a chloroma in the perineum. The chloroma was treated with local radiotherapy. The chloroma recurred 8 mo later and was treated with radiotherapy followed by combination chemotherapy. At 34 mo after transplant, marrow relapse and chloroma were documented. The first chloroma contained host cells by fluorescent Y-chromatin body analyses of interphase nuclei. All metaphase cells and karyotypes from peripheral blood and marrow samples showed no evidence of host cells from 3 wk after transplant through the time of marrow relapse. Data from autosomal and sex chromosome studies indicate that the marrow relapse occurred in cells of donor origin. A new consistent chromosome abnormality [45, X, -X, t(8;21) (q22; q22)] was observed in a majority of donor cells. The patient received a second bone marrow transplant from the same donor after preparation with busulfan and cyclophosphamide and attained a complete remission with full hematologic engraftment.

Adult↗
PubMed1978

Efficacy of granulocyte transfusions in the control of systemic candidiasis in the leukopenic host.

An experimental canine model was designed to evaluate the effect of granulocyte transfusions on systemic infection with Candida albicans in the granulocytopenic host. Each of a pair of dogs was rendered granulocytopenic with a single intravenous (i.v.) dose of cyclophosphamide (50 mg/kg body weight) and challenged with 10(6) Candida albicans organisms administered i.v. when granulocyte counts were less than or equal to 500/mm3. Granulocytes procured by leukofiltration were infused into six experimental dogs 1, 24, 48, and 72 hr after challenge with Candida. An average of 13 +/- 1.3 X 10(9) granulocytes were administered per infusion, producing an average 1-hr increment of 588 +/- 146 granulocytes/mm3 over the pretransfusion granulocyte count. Experimental and control dogs were killed 96 hr after challenge and organs examined grossly and by quantitative culture techniques to measure the extent of infection. All animals receiving granulocyte transfusions had significantly less tissue infection than nontransfused controls (p less than 0.05). It was concluded that granulocyte transfusions are effective in reducing the severity of infection by Candida albicans during periods of leukopenia.

Animals↗
PubMed1977

Intralesional Bacillus Calmette-Guérin immunotherapy of canine venereal tumors.

Canine transmissible venereal tumors were studied for response to intralesional Bacillus Calmette-Guérin (BCG) therapy. Six pairs of littermates, identical for the major histocompatibility complex, were evaluated. One member of each pair received intralesional BCG to one of two growing tumors. Lesions of control animals received 0.9% NaCl solution. Both injected and noninjected lesions of BCG-treated animals underwent regression within 63 days, as compared to an extended period of tumor growth (beyond 100 days) for controls (p less than 0.05). Serial in vitro assays during therapy included; (a) mixed lymphocyte-tumor culture, (b) phytohemagglutinin stimulation, and (c) assessment of lymphocyte surface markers. Lymphocytes from BCG-treated dogs were significantly more responsive to tumor cells in mixed lymphocyte-tumor culture assay than were those from controls (p less than 0.05). Maximal responses occurred during tumor regression. T- and B-lymphocyte levels as assayed by rosette formation and surface marker immunoglobulins were not influenced by BCG therapy. It was concluded that intralesional BCG therapy of canine venereal tumors was highly effective in causing regression of injected and noninjected lesions. This tumor model system may be useful for the evaluation of the effectiveness of new immunotherapeutic approaches on established neoplasms in large, randomly bred animals.

Animals↗
PubMed1977

Demonstration of hemopoietic stem cells in the peripheral blood of baboons by cross circulation.

Baboons were given 1200 R total body irradiation from two opposing 60Co sources. Three animals were given supportive therapy only and died, as expected, within 8 days of irradiation with profound marrow hypoplasia. Five baboons were cross-circulated with unirradiated partners and died within 14 days with evidence suggestive of graft-versus-host disease. Their marrows were repopulated with hemopoietic precursor cells, and three of the five had rises in peripheral white blood cell counts to more than 1500/cu mm before death. These results are compatible with the presence of hemopoietic stem cells in the peripheral blood of a nonhuman primate, the baboon.

ABO Blood-Group System↗
PubMed1976

Effect of bone marrow suppression on granulocyte opsonin levels.

Levels of serum opsonin for neutrophilic granulocytes were measured in dogs made neutropenic by cyclophosphamide administration. Heat-labile opsonin became elevated within 24 hr following cyclophosphamide (P less than 0.005) and remained elevated over the 4-5 day period of observation (P less than 0.005). In contrast, heat stable opsonin was not significantly effected. Bone marrow suppression by X-ray and busulfan also caused serum opsonin levels to increase. Changes in the levels of IgG, C3, and total hemolytic complement during the course of bone marrow suppression did not correlate with the granulocyte opsonin levels. These findings suggest that serum granulocyte opsonin levels respond to bone marrow suppression and may provide an improved environment for the function of transfused granulocytes.

Agranulocytosis↗
PubMed1976

Combined pre-immunization and granulocyte transfusion therapy for treatment of pseudomonas septicemia in neutropenic dogs.

An experimental model was designed to evaluate a combined protocol of active immunization and granulocyte transfusions for treatment of Pseudomonas aeruginosa sepsis in the neutropenic host. One member of a pair of dogs was immunized with P. aeruginosa vaccine. Both dogs were then rendered transiently neutropenic with a single intravenous dose of cyclophosphamide (40 mg. per kilogram) and challenged with an intravenous inoculum of P. aeruginosa. Twenty-four and 48 hours after pseudomonas challenge each animal received granulocyte transfusions. Effectiveness of therapy was evaluated by observation of survival time, febrile response, and quantitative blood cultures. Results showed a significant increase in the survival period (P is less than 0.05), a lower febrile response (P is less than 0.025), negative blood cultures, and a greater recovery rate in the immune group. Immune dogs that died had negative blood cultures or less than or equal to 10 pseudomonas per milliliter of blood despite the presence of P. aeruginosa in tissues. In contrast, control dogs had septic deaths within 67 hours of pseudomonas challenge, marked febrile responses with 24 hours of infection, and positive blood cultures with 4,000 to 25,800 pseudomonas per milliliter of blood. These data show that combined therapy with immunization and granulocyte transfusions is effective in reducing the severity of P. aeruginosa infection and in preventing bacteremia during periods of leukopenia.

Agranulocytosis↗