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In JoVE (1)
Other Publications (3)
Articles by Farshad C. Azimi in JoVE
JoVE General
A Convenient and General Expression Platform for the Production of Secreted Proteins from Human Cells
Department of Laboratory Medicine and Pathobiology, University of Toronto
In the post-human genomics era, the availability of recombinant proteins in native conformations is crucial to structural, functional and therapeutic research and development. Here, we describe a test- and large-scale protein expression system in human embryonic kidney 293T cells that can be used to produce a variety of recombinant proteins.
Other articles by Farshad C. Azimi on PubMed
Repression of IRF-4 Target Genes in Human T Cell Leukemia Virus-1 Infection
The human T cell leukemia/lymphotropic virus-1 (HTLV-I) is the etiologic agent of adult T cell leukemia (ATL), an aggressive and fatal leukemia of CD4+ T lymphocytes. Interferon regulatory factor-4 (IRF-4) was shown previously to be constitutively expressed in T cells infected with HTLV-1. In this study, we investigated the role of IRF-4 gene regulation in the context of HTLV-1 infection using gene array technology and IRF-4 expressing T cells. Many potential IRF-4 regulated genes were identified, the vast majority of which were repressed by IRF-4 expression. Cyclin B1, a G2-M checkpoint protein identified as an IRF-4 repressed gene in the array, was further characterized in the context of HTLV-1 infection. All HTLV-1 infected cell lines and ATL patient lymphocytes demonstrated a dramatic decrease in cyclin B1 levels; subsequent analysis of the cyclin B1 promoter identified two sites important in IRF-4 binding and repression of cyclin B1 expression. Furthermore, IRF-4-mediated repression of cyclin B1 led to a significant decrease in CDC2 kinase activity in HTLV-1 infected T cells. IRF-4 expression in HTLV-1 infected T cells also downregulated other genes implicated in the mitotic checkpoint as well as genes involved in actin cytoskeletal rearrangement, DNA repair, apoptosis, metastasis and immune recognition. Several of the identified genes are dysregulated in ATL and may provide important mechanistic information concerning pathways critical to the emergence of ATL.
Population Structure of Invasive and Colonizing Strains of Streptococcus Agalactiae from Neonates of Six U.S. Academic Centers from 1995 to 1999
The purpose of this study was to describe the population structure of group B streptococci (GBS) isolated from infected and colonized neonates during a prospective active-surveillance study of early-onset disease in six centers in the United States from July 1995 to June 1999 and to examine its relationship to bovine strains of GBS. The phylogenetic lineage of each GBS isolate was determined by multilocus sequence typing, and isolates were clustered into clonal complexes (CCs) using the eBURST software program. A total of 899 neonatal GBS isolates were studied, of which 129 were associated with invasive disease. Serotype Ia, Ib, and V isolates were highly clonal, with 92% to 96% of serotype Ia, Ib, and V isolates being confined to single clonal clusters. In contrast, serotype II and III isolates were each comprised of two major clones, with 39% of serotype II and 41% of serotype III isolates in CC 17 and 41% of serotype II and 54% of serotype III isolates in CC 19. Further analysis demonstrates that the CC 17 serotype II and III GBS are closely related to a previously described "ancestral" lineage of bovine GBS. While 120 (93%) of invasive GBS were confined to the same lineages that colonized neonates, 9 (7%) of the invasive GBS isolates were from rare lineages that comprised only 2.7% of colonizing lineages. These results are consistent with those for other geographic regions that demonstrate the highly clonal nature of GBS infecting and colonizing human neonates.
Hepatocytes of Donor Origin in Recipient Liver After Hematopoietic SCT in Beta-thalassemia Major Patients
BM and circulating cells contain stem cells with the potential to differentiate into mature cells of various organs. We determined whether stem cells transformed into hepatocytes. Biopsy specimens from liver were obtained from 11 patients who had undergone transplantation of hematopoietic stem cells from peripheral blood (eight patients) or BM (three patients). Four female patients had received transplants from a male donor and seven male patients had received transplants from a female donor. All patients had beta-thalassemia major and fibrosis in biopsy specimens from the liver before hematopoietic SCT. Hematopoietic stem cell engraftment was verified by STR analysis. The biopsies were studied for the presence of donor-derived hepatocytes using FISH of interphase nuclei and immunohistochemical staining for CD45 (leukocyte common Ag), and a hepatocyte-specific Ag. All 11 recipients of sex-mismatched transplants showed evidence of complete hematopoietic donor chimerism. XY-positive hepatocytes accounted for 4-6.7% of cells in histological sections of the biopsy specimens of female patients and XX-positive hepatocytes accounted for 3-7% of cells in histological sections of the biopsy specimens of male patients. These cells were detected in liver tissue as early as 1 year and as late as 8.5 years after hematopoietic SCT. BM and circulating stem cells can differentiate into mature hepatocytes in beta-thalassemia major patients who had undergone hematopoietic SCT.
