J. Pistillo - Academia.edu (original) (raw)

Papers by J. Pistillo

Biochemical and biophysical research communications, Jan 29, 1990

Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation ... more Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation of viral DNA replication, regulation of viral transcription and cell transformation. Bacterial expression vectors, pER23-1 and pER23-2, that are based on the regulatable rac promoter were used to produce T antigen either as a free protein or as a fusion protein. We have observed efficient transcription of the cloned T antigen gene in most of the recombinants. However, expression of the T antigen protein was inefficient and most of the expressed protein was truncated. This may be due to differences in codon usage in E. coli or to rapid protein degradation.

Lupus, 2002

Thrombocytopenia is a common phenomenon in patients suffering from systemic lupus erythematosus (... more Thrombocytopenia is a common phenomenon in patients suffering from systemic lupus erythematosus (SLE). The cause of thrombocytopenia in SLE, however, is poorly understood. In this study, 100 patients with SLE were evaluated for serum thrombopoietin levels, anti-thrombopoietin antibodies and routine laboratory parameters such as peripheral blood counts, parameters of blood chemistry and immunologic parameters of SLE. The median platelet count of SLE patients was 230 g/l and 19 were thrombocytopenic (range 8-148 g/l). Thrombopoietin levels in SLE patients were found to be significantly higher than in healthy controls (n = 96; median, 117 pg/ml vs 64 pg/ml, P < 0.01). When excluding thrombocytopenic SLE patients, thrombopoietin levels in SLE were still above controls (111 pg/ml, P < 0.01). The thrombopoietin levels were correlated to erythrocyte sedimentation rate and ECLAM score of disease activity, and inversely correlated to complement factor C4, but not to the platelet count. Anti-thrombopoietin antibody reactivity was found in 23% of SLE patients. Interestingly, these patients had lower platelet counts than SLE patients without anti-thrombopoietin antibodies (median 174 g/l and 253 g/l, respectively, P < 0.01), but thrombopoietin levels were not significantly different. Taken together, thrombopoietin levels are significantly higher in the sera of SLE patients than in healthy controls and anti-thrombopoietin antibodies are frequently found.

Experimental Hematology, 2001

We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of... more We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of the associated anemia of chronic disorders (ACD), to evaluate the similarity of this ACD model to human ACD, and to evaluate the potential efficacy of novel erythropoiesis stimulating protein (darbepoetin alfa) as an ACD therapy. Methods. Lewis rats were immunized with peptidoglycan-polysaccharide polymers (PG-APS), the chronic inflammation and associated ACD were characterized, and the effects of darbepoetin alfa treatment on complete blood counts (CBC), red blood cell (RBC) indices, and iron metabolism were analyzed weekly.

Experimental Hematology, 2001

Objective. Therapeutic use of recombinant human cytokines in humans can result in the generation ... more Objective. Therapeutic use of recombinant human cytokines in humans can result in the generation of drug-specific antibodies. To predetermine the maximum potential effects of a granulocyte colony-stimulating factor (G-CSF) neutralizing auto-immunoglobulin G (auto-IgG) response during recombinant human G-CSF therapy, we developed a mouse model of mouse G-CSF (mG-CSF) neutralizing auto-IgG response. Materials and Methods. Mice were immunized and boosted with mG-CSF chemically conjugated to either keyhole limpet hemocyanin or ovalbumin on an alternating schedule. Sera were analyzed for mG-CSF-specific titers and full blood counts were performed on a Technicon H-1E. On day 252, tissues were collected for histology. IgG was protein A affinity purified from pooled mG-CSF autoimmune sera. Results. Mice immunized with mG-CSF conjugates produced mG-CSF-specific auto-IgG responses that lasted for the length of the study. Significant neutropenia ( p max Ͻ 0.004) was concurrent with the rise in mG-CSF-specific IgG titers. However, neutrophil counts remained at ‫ف‬ 20% of preimmunization levels through day 252. Endogenous mG-CSF neutralizing auto-IgG had no significant effect on hemoglobin, erythrocyte, lymphocyte, eosinophil, basophil, and platelet counts, and had minor, transient, or no effects on monocyte counts. Bone marrow colony assays from mG-CSF autoimmune mice demonstrated no significant effect of G-CSF neutralization on the numbers or proliferative capacity of preneutrophil lineage progenitors. Purified IgG from mG-CSF autoimmune mice neutralized mG-CSF in vitro. Conclusion. High-titer G-CSF neutralizing auto-IgG in adult mice partially inhibited steadystate granulopoiesis and had little or no effect on steady-state levels of other hematopoietic cells.

Biochemical and Biophysical Research Communications, 1990

Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation ... more Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation of viral DNA replication, regulation of viral transcription and cell transformation. Bacterial expression vectors, pER23-1 and pER23-2, that are based on the regulatable rac promoter were used to produce T antigen either as a free protein or as a fusion protein. We have observed efficient transcription of the cloned T antigen gene in most of the recombinants. However, expression of the T antigen protein was inefficient and most of the expressed protein was truncated. This may be due to differences in codon usage in E. coli or to rapid protein degradation.

Archives of Virology, 1991

Simian virus 40 (SV40) large T antigen binds to host cell DNA polymerase a and the T-antigen-DNA ... more Simian virus 40 (SV40) large T antigen binds to host cell DNA polymerase a and the T-antigen-DNA polymerase (~ complex is implicated in the initiation of viral DNA replication. We have examined various SV40 Tantigen mutants to test the correspondence between viral DNA replication and T-antigen-DNA polymerase a complex formation. The various SV40 T-antigen mutants were used to either infect or transfect African green monkey kidney cell line CV-1, and at different time intervals we measured the production of T-antigen and host cell DNA polymerase a by radioimmunoassay, complex formation by a sandwich radioimmunoassay and the amount of viral DNA synthesis by dot-blot hybridization analysis. There was a good correlation between complex formation and viral DNA synthesis in lytic mutants of SV40. Poor complex formation and correspondingly lower DNA synthesis were observed in the non-viable mutants of SV40, even though significant amounts of T-antigen and DNA polymerase c~ were present. Our results substantiate the earlier findings of T-antigen-DNA polymerase a complex formation and establish the need for formation of this complex in promoting viral DNA synthesis.

International Immunology, 2000

Optimal T cell activation requires the interactions of co-stimulatory molecules, such as those in... more Optimal T cell activation requires the interactions of co-stimulatory molecules, such as those in the CD28 and B7 protein families. Recently, we described the co-stimulatory properties of the murine ligand to ICOS, which we designated as B7RP-1. Here, we report the co-stimulation of human T cells through the human B7RP-1 and ICOS interaction. This ligand-receptor pair interacts with a K D~3 3 nM and an off-rate with a t 1/2 Ͼ 10 min.

Biochemical and biophysical research communications, Jan 29, 1990

Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation ... more Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation of viral DNA replication, regulation of viral transcription and cell transformation. Bacterial expression vectors, pER23-1 and pER23-2, that are based on the regulatable rac promoter were used to produce T antigen either as a free protein or as a fusion protein. We have observed efficient transcription of the cloned T antigen gene in most of the recombinants. However, expression of the T antigen protein was inefficient and most of the expressed protein was truncated. This may be due to differences in codon usage in E. coli or to rapid protein degradation.

Lupus, 2002

Thrombocytopenia is a common phenomenon in patients suffering from systemic lupus erythematosus (... more Thrombocytopenia is a common phenomenon in patients suffering from systemic lupus erythematosus (SLE). The cause of thrombocytopenia in SLE, however, is poorly understood. In this study, 100 patients with SLE were evaluated for serum thrombopoietin levels, anti-thrombopoietin antibodies and routine laboratory parameters such as peripheral blood counts, parameters of blood chemistry and immunologic parameters of SLE. The median platelet count of SLE patients was 230 g/l and 19 were thrombocytopenic (range 8-148 g/l). Thrombopoietin levels in SLE patients were found to be significantly higher than in healthy controls (n = 96; median, 117 pg/ml vs 64 pg/ml, P < 0.01). When excluding thrombocytopenic SLE patients, thrombopoietin levels in SLE were still above controls (111 pg/ml, P < 0.01). The thrombopoietin levels were correlated to erythrocyte sedimentation rate and ECLAM score of disease activity, and inversely correlated to complement factor C4, but not to the platelet count. Anti-thrombopoietin antibody reactivity was found in 23% of SLE patients. Interestingly, these patients had lower platelet counts than SLE patients without anti-thrombopoietin antibodies (median 174 g/l and 253 g/l, respectively, P < 0.01), but thrombopoietin levels were not significantly different. Taken together, thrombopoietin levels are significantly higher in the sera of SLE patients than in healthy controls and anti-thrombopoietin antibodies are frequently found.

Experimental Hematology, 2001

We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of... more We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of the associated anemia of chronic disorders (ACD), to evaluate the similarity of this ACD model to human ACD, and to evaluate the potential efficacy of novel erythropoiesis stimulating protein (darbepoetin alfa) as an ACD therapy. Methods. Lewis rats were immunized with peptidoglycan-polysaccharide polymers (PG-APS), the chronic inflammation and associated ACD were characterized, and the effects of darbepoetin alfa treatment on complete blood counts (CBC), red blood cell (RBC) indices, and iron metabolism were analyzed weekly.

Experimental Hematology, 2001

Objective. Therapeutic use of recombinant human cytokines in humans can result in the generation ... more Objective. Therapeutic use of recombinant human cytokines in humans can result in the generation of drug-specific antibodies. To predetermine the maximum potential effects of a granulocyte colony-stimulating factor (G-CSF) neutralizing auto-immunoglobulin G (auto-IgG) response during recombinant human G-CSF therapy, we developed a mouse model of mouse G-CSF (mG-CSF) neutralizing auto-IgG response. Materials and Methods. Mice were immunized and boosted with mG-CSF chemically conjugated to either keyhole limpet hemocyanin or ovalbumin on an alternating schedule. Sera were analyzed for mG-CSF-specific titers and full blood counts were performed on a Technicon H-1E. On day 252, tissues were collected for histology. IgG was protein A affinity purified from pooled mG-CSF autoimmune sera. Results. Mice immunized with mG-CSF conjugates produced mG-CSF-specific auto-IgG responses that lasted for the length of the study. Significant neutropenia ( p max Ͻ 0.004) was concurrent with the rise in mG-CSF-specific IgG titers. However, neutrophil counts remained at ‫ف‬ 20% of preimmunization levels through day 252. Endogenous mG-CSF neutralizing auto-IgG had no significant effect on hemoglobin, erythrocyte, lymphocyte, eosinophil, basophil, and platelet counts, and had minor, transient, or no effects on monocyte counts. Bone marrow colony assays from mG-CSF autoimmune mice demonstrated no significant effect of G-CSF neutralization on the numbers or proliferative capacity of preneutrophil lineage progenitors. Purified IgG from mG-CSF autoimmune mice neutralized mG-CSF in vitro. Conclusion. High-titer G-CSF neutralizing auto-IgG in adult mice partially inhibited steadystate granulopoiesis and had little or no effect on steady-state levels of other hematopoietic cells.

Biochemical and Biophysical Research Communications, 1990

Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation ... more Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation of viral DNA replication, regulation of viral transcription and cell transformation. Bacterial expression vectors, pER23-1 and pER23-2, that are based on the regulatable rac promoter were used to produce T antigen either as a free protein or as a fusion protein. We have observed efficient transcription of the cloned T antigen gene in most of the recombinants. However, expression of the T antigen protein was inefficient and most of the expressed protein was truncated. This may be due to differences in codon usage in E. coli or to rapid protein degradation.

Archives of Virology, 1991

Simian virus 40 (SV40) large T antigen binds to host cell DNA polymerase a and the T-antigen-DNA ... more Simian virus 40 (SV40) large T antigen binds to host cell DNA polymerase a and the T-antigen-DNA polymerase (~ complex is implicated in the initiation of viral DNA replication. We have examined various SV40 Tantigen mutants to test the correspondence between viral DNA replication and T-antigen-DNA polymerase a complex formation. The various SV40 T-antigen mutants were used to either infect or transfect African green monkey kidney cell line CV-1, and at different time intervals we measured the production of T-antigen and host cell DNA polymerase a by radioimmunoassay, complex formation by a sandwich radioimmunoassay and the amount of viral DNA synthesis by dot-blot hybridization analysis. There was a good correlation between complex formation and viral DNA synthesis in lytic mutants of SV40. Poor complex formation and correspondingly lower DNA synthesis were observed in the non-viable mutants of SV40, even though significant amounts of T-antigen and DNA polymerase c~ were present. Our results substantiate the earlier findings of T-antigen-DNA polymerase a complex formation and establish the need for formation of this complex in promoting viral DNA synthesis.

International Immunology, 2000

Optimal T cell activation requires the interactions of co-stimulatory molecules, such as those in... more Optimal T cell activation requires the interactions of co-stimulatory molecules, such as those in the CD28 and B7 protein families. Recently, we described the co-stimulatory properties of the murine ligand to ICOS, which we designated as B7RP-1. Here, we report the co-stimulation of human T cells through the human B7RP-1 and ICOS interaction. This ligand-receptor pair interacts with a K D~3 3 nM and an off-rate with a t 1/2 Ͼ 10 min.