Other articles by Scott Cooper on PubMed

• Enhancement of Intracellular Signaling Associated with Hematopoietic Progenitor Cell Survival in Response to SDF-1/CXCL12 in Synergy with Other Cytokines Blood. Jun, 2002  |   Pubmed ID: 12036856 Stromal cell-derived factor 1 (SDF-1/CXCL12) is a multifunctional cytokine. We previously reported that myelopoiesis was enhanced in SDF-1 alpha transgenic mice, probably due in part to SDF-1 alpha enhancement of myeloid progenitor cell (MPC) survival. To understand signaling pathways involved in this activity, we studied the effects on factor-dependent cell line MO7e cells incubated with SDF-1 alpha alone or in combination with other cytokines. SDF-1 alpha induced transient activation of extracellular stress-regulated kinase (ERK1/2), ribosomal S6 kinase (p90RSK) and Akt, molecules implicated in cell survival. Moreover, ERK1/2, p90RSK, and Akt were synergistically activated by SDF-1 alpha in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), Steel factor (SLF), or thrombopoietin (TPO). Similar effects were seen after pretreatment of MO7e cells with SDF-1 alpha followed by stimulation with the other cytokines, suggesting a priming effect of SDF-1 alpha. Nuclear factor-kappa B (NF-kappa B) did not appear to be involved in SDF-1 alpha actions, alone or in combination with other cytokines. These intracellular effects were consistent with enhanced myeloid progenitor cell survival by SDF-1 alpha after delayed addition of growth factors. SDF-1 alpha alone supported survival of highly purified human cord blood CD34(+++) cells, less purified human cord blood, and MO7e cells; this effect was synergistically enhanced when SDF-1 alpha was combined with low amounts of other survival-promoting cytokines (GM-CSF, SLF, TPO, and FL). SDF-1 may contribute to maintenance of MPCs in bone marrow by enhancing cell survival alone and in combination with other cytokines.
• Th1 Cells Regulate Hematopoietic Progenitor Cell Homeostasis by Production of Oncostatin M Immunity. Jun, 2002  |   Pubmed ID: 12121663 Regulation of hematopoietic progenitor cell homeostasis is crucial for maintenance of innate immunity and the ability of the body to respond to injury and infection. In this report, we demonstrate that progenitor cell numbers and cycling status in vivo are dramatically increased in mice deficient in Stat6 and decreased in mice deficient in Stat4, targeted mutations which also alter T helper cell polarization. Experiments using mice that have T cell restricted transgenic expression of Stat4 or Stat6 or have been in vivo depleted of T cell subsets demonstrate that CD4(+) T cells regulate progenitor cell activity. Injection of the Th1 cytokine Oncostatin M but not other cytokines into Stat4-deficient mice recovers progenitor cell activity to wild-type levels. Thus, T helper cells actively regulate hematopoietic progenitor cell homeostasis.
• The Chemokine CCL21 Protects Normal Marrow Progenitors from Ara-C Cytotoxicity Cancer Chemotherapy and Pharmacology. Aug, 2002  |   Pubmed ID: 12172984 Chemokines are a family of small proteins that regulate leukocyte infiltration into inflamed tissue and play key roles in the pathogenesis of many diseases. Some chemokines can also reversibly inhibit the proliferation of hematopoietic progenitors. We have previously found that the chemokine CCL21 (Exodus-2/SLC/6Ckine/TCA4) is a potent inhibitor of the proliferation of normal hematopoietic progenitors. In this study we sought to determine whether this inhibition of proliferation could be therapeutically exploited by protecting normal marrow progenitors from the cytotoxicity of the S phase-active chemotherapeutic agent Ara-C.
• Peripheral Blood Stem Cell Mobilization. A Role for CXC Chemokines Critical Reviews in Oncology/hematology. Sep, 2002  |   Pubmed ID: 12270782 Chemokines induce rapid hematopoietic stem and progenitor cell mobilization and synergize with hematopoietic cytokines in mobilizing stem and progenitor cells. These proteins alone and in combination offer new paradigms for autologous and allogeneic peripheral blood stem cell transplantation (PBSCT). The mechanisms responsible for hematopoietic stem cell (HSC) mobilization either with growth factors or chemokines are largely unknown, but a better understanding of these mechanisms will permit the development of novel, more rapid and efficacious regimens. Studies presented herein indicate that the CXCR2 chemokine receptor that interacts with selective chemokine ligands, particularly GRObeta/CXCL2 and GRObeta-T, may be the dominant receptor mediating hematopoietic cell mobilization, and that polymorphonuclear neutrophils may be the primary CXCR2 expressing target cell for stem and progenitor cell mobilization.
• Inhibition of a Thrombin Anion-binding Exosite-2 Mutant by the Glycosaminoglycan-dependent Serpins Protein C Inhibitor and Heparin Cofactor II Thrombosis Research. Jul, 2002  |   Pubmed ID: 12413592 Antithrombin (ATIII), heparin cofactor II (HCII) and protein C inhibitor (PCI; also named plasminogen activator inhibitor-3) are serine protease inhibitors (serpins) whose thrombin inhibition activity is accelerated in the presence of glycosaminoglycans. We compared the inhibition properties of PCI and HCII to ATIII using R93A/R97A/R101A thrombin, an anion-binding exosite-2 (exosite-2) mutant that has greatly reduced heparin-binding properties. Heparin-enhanced PCI inhibition of R93A/R97A/R101A thrombin was only approximately 2-fold compared to 40-fold enhancement with wild-type recombinant thrombin. Thrombomodulin (TM) (with or without the chondroitin sulfate moiety) accelerated PCI inhibition of both wild-type and R93A/R97A/R101A thrombins. HCII achieved the same maximum activity in the presence of heparin with both wild-type and R93A/R97A/R101A thrombins; however, the optimum heparin concentration was 20 times greater than the reaction with wild-type thrombin, indicative of a decrease in heparin affinity. Dermatan sulfate (DSO4)-catalyzed HCII thrombin inhibition was unchanged in R93A/R97A/R101A thrombin compared to wild-type recombinant thrombin. These results suggest that PCI is similar to ATIII and depends upon ternary complex formation with heparin and these specific thrombin exosite-2 residues to accelerate thrombin inhibition. In contrast, HCII does not require Arg(93), Arg(97) and Arg(101) of thrombin exosite-2 and further supports the hypothesis that HCII uses an allosteric process following glycosaminoglycan binding to inhibit thrombin.
• Down-regulation of the Myeloid Homeobox Protein Hex is Essential for Normal T-cell Development Immunology. Dec, 2002  |   Pubmed ID: 12460189 The haematopoietic homeobox gene Hex (also called Prh) is expressed in myeloid cells and B cells but not T cells. To investigate whether Hex levels might play a role in myeloid versus T-cell development, two types of transgenic mouse lines were constructed, each with ectopic expression of Hex in T cells (CD11a/Hex and Lck/Hex). Both these types of transgenic mouse had the same defects in T-cell maturation, indicating that proper T-cell development may be dependent not just on the up-regulation of lymphoid-specific transcriptional regulators but also on the co-ordinated down-regulation of myeloid-specific transcriptional regulators such as Hex. In addition, Hex over-expression significantly increased myeloid progenitor cycling, which may explain its role in retrovirally induced murine leukaemia.
• Transgenic Expression of Stromal Cell-derived Factor-1/CXC Chemokine Ligand 12 Enhances Myeloid Progenitor Cell Survival/antiapoptosis in Vitro in Response to Growth Factor Withdrawal and Enhances Myelopoiesis in Vivo Journal of Immunology (Baltimore, Md. : 1950). Jan, 2003  |   Pubmed ID: 12496427 Hemopoiesis is regulated in part by survival/apoptosis of hemopoietic stem/progenitor cells. Exogenously added stromal cell-derived factor-1 ((SDF-1)/CXC chemokine ligand (CXCL)12) enhances survival/antiapoptosis of myeloid progenitor cells in vitro. To further evaluate SDF-1/CXCL12 effects on progenitor cell survival, transgenic mice endogenously expressing SDF-1/CXCL12 under a Rous sarcoma virus promoter were produced. Myeloid progenitors (CFU-granulocyte-macrophage, burst-forming unit-erythroid, CFU-granulocyte-erythrocyte-megakaryocyte-monocyte) from transgenic mice were studied for in vitro survival in the context of delayed addition of growth factors. SDF-1-expressing transgenic myeloid progenitors were enhanced in survival and antiapoptosis compared with their wild-type littermate counterparts. Survival-enhancing effects were due to release of low levels of SDF-1/CXCL12 and mediated through CXCR4 and G(alpha)i proteins as determined by ELISA, an antagonist to CXCR4, Abs to CXCR4 and SDF-1, and pertussis toxin. Transgenic effects of low SDF-1/CXCR4 may be due to synergy of SDF-1/CXCL12 with other cytokines; low SDF-1/CXCL12 synergizes with low concentrations of other cytokines to enhance survival of normal mouse myeloid progenitors. Consistent with in vitro results, progenitors from SDF-1/CXCL12 transgenic mice displayed enhanced marrow and splenic myelopoiesis: greatly increased progenitor cell cycling and significant increases in progenitor cell numbers. These results substantiate survival effects of SDF-1/CXCL12, now extended to progenitors engineered to endogenously produce low levels of this cytokine, and demonstrate activity in vivo for SDF-1/CXCL12 in addition to cell trafficking.
• High-efficiency Recovery of Functional Hematopoietic Progenitor and Stem Cells from Human Cord Blood Cryopreserved for 15 Years Proceedings of the National Academy of Sciences of the United States of America. Jan, 2003  |   Pubmed ID: 12518050 Transplanted cord blood (CB) hematopoietic stem cells (HSC) and progenitor cells (HPC) can treat malignant and nonmalignant disorders. Because long-term cryopreservation is critical for CB banking and transplantation, we assessed the efficiency of recovery of viable HSCHPC from individual CBs stored frozen for 15 yr. Average recoveries (+/- 1 SD) of defrosted nucleated cells, colony-forming unit-granulocyte, -macrophage (CFU-GM), burst-forming unit-erythroid (BFU-E), and colony-forming unit-granulocyte, -erythrocyte, -monocyte, and -megakaryocyte (CFU-GEMM) were, respectively, 83 +/- 12, 95 +/- 16, 84 +/- 25, and 85 +/- 25 using the same culture conditions as for prefreeze samples. Proliferative capacities of CFU-GM, BFU-E, and CFU-GEMM were intact as colonies generated respectively contained up to 22,500, 182,500, and 292,500 cells. Self-renewal of CFU-GEMM was also retained as replating efficiency of single CFU-GEMM colonies into 2 degrees dishes was >96% and yielded 2 degrees colonies of CFU-GM, BFU-E, and CFU-GEMM. Moreover, CD34(+)CD38(-) cells isolated by FACS after thawing yielded >250-fold ex vivo expansion of HPC. To assess HSC capability, defrosts from single collections were bead-separated into CD34(+) cells and infused into sublethally irradiated nonobese diabetic (NOD)severe combined immunodeficient (SCID) mice. CD45(+) human cell engraftment with multilineage phenotypes was detected in mice after 11-13 wk; engrafting levels were comparable to that reported with fresh CB. Thus, immature human CB cells with high proliferative, replating, ex vivo expansion and mouse NODSCID engrafting ability can be stored frozen for >15 yr, can be efficiently retrieved, and most likely remain effective for clinical transplantation.
• Identification of a Functional Link for the P53 Tumor Suppressor Protein in Dexamethasone-induced Growth Suppression The Journal of Biological Chemistry. Mar, 2003  |   Pubmed ID: 12519780 Serine/threonine phosphatase 5 (PP5) can act as a suppresser of p53-dependent growth suppression and has been reported to associate with several proteins, including the glucocorticoid receptor/heat-shock protein-90 complex. Still, the physiological/pathological roles of PP5 are unclear. To characterize the relationship of PP5, glucocorticoid receptor activation and p53, here we describe the development of chimeric antisense oligonucleotides that potently inhibit human p53 expression. This allowed us to regulate the expression of either p53 (e.g. with ISIS 110332) or PP5 (e.g. with ISIS 15534) in genetically identical cells. Studies with ISIS 110332 revealed that the suppression of p53 expression is associated with a decrease in the basal expression of the cyclin-dependent kinase inhibitor protein, p21(WAF1/Cip1), and a concomitant increase in the rate of cell proliferation. Suppression of p53 also blocks dexamethasone-induced p21(WAF1/Cip1) expression and G(1)-growth arrest. Furthermore, treatment with ISIS 110332, but not the mismatched controls, ablates the suppression of growth produced by prior treatment with dexamethasone. Additional studies revealed that dexamethasone-dependent p21(WAF1/Cip1) expression occurs without an apparent change in p53 protein levels or the phosphorylation status of p53 at Ser-6, -37, or -392. However, dexamethasone treatment is associated with an increase in p53 phosphorylation at Ser-15. Suppression of PP5 expression with ISIS 15534 also results in the hyperphosphorylation of p53 at Ser-15. Together, these findings indicate that the basal expression of p53 plays a functional role in a glucocorticoid receptor-mediated response regulating the expression of p21(Waf1/Cip1) via a mechanism that is suppressed by PP5 and associated with the phosphorylation of p53 at Ser-15.
• Cell Surface Peptidase CD26/DPPIV Mediates G-CSF Mobilization of Mouse Progenitor Cells Blood. Jun, 2003  |   Pubmed ID: 12576320 CXC ligand 12 (CXCL12; also known as stromal cell-derived factor 1alpha/SDF-1alpha) chemoattracts hematopoietic stem and progenitor cells (HSCs/HPCs) and is thought to play a crucial role in the mobilization of HSCs/HPCs from the bone marrow. CD26 (dipeptidylpeptidase IV [DPPIV]) is a membrane-bound extracellular peptidase that cleaves dipeptides from the N-terminus of polypeptide chains. CD26 has the ability to cleave CXCL12 at its position-2 proline. We found by flow cytometry that CD26 is expressed on a subpopulation of normal Sca-1+c-kit+lin- hematopoietic cells isolated from mouse bone marrow, as well as Sca-1+c-kit-lin- cells, and that these cells possess CD26 peptidase activity. To test the functional role of CD26 in CXCL12-mediated normal HSC/HPC migration, chemotaxis assays were performed. The CD26 truncated CXCL12(3-68) showed an inability to induce the migration of sorted Sca-1+c-kit+lin- or Sca-1+c-kit-lin- mouse marrow cells compared with the normal CXCL12. In addition, CXCL12(3-68) acts as an antagonist, resulting in the reduction of migratory response to normal CXCL12. Treatment of Sca-1+c-kit+lin- mouse marrow cells, and myeloid progenitors within this population, or Sca-1+c-kit-lin- cells with a specific CD26 inhibitor, enhanced the migratory response of these cells to CXCL12. Finally, to test for potential in vivo relevance of these in vitro observations, mice were treated with CD26 inhibitors during granulocyte colony-stimulating factor (G-CSF)-induced mobilization. This treatment resulted in a reduction in the number of progenitor cells in the periphery as compared with the G-CSF regimen alone. This suggests that a mechanism of action of G-CSF mobilization involves CD26.
• Profiling of Differentially Expressed Apoptosis-related Genes by CDNA Arrays in Human Cord Blood CD34+ Cells Treated with Etoposide Experimental Hematology. Mar, 2003  |   Pubmed ID: 12644023 Understanding the molecular events that contribute to survival of and drug-induced apoptosis in hematopoietic stem and progenitor cells (HSC/P) can have impact on more rational approaches to blood cancer therapeutic design, as well as on strategies to minimize toxic side effects of chemotherapeutic drugs. Here we sought to systematically evaluate the basic molecular components and main pathways that govern and mediate cellular response initiated within human CD34(+) cells to etoposide-induced apoptosis.
• Stromal Cell-derived Factor-1/CXCL12 Directly Enhances Survival/antiapoptosis of Myeloid Progenitor Cells Through CXCR4 and G(alpha)i Proteins and Enhances Engraftment of Competitive, Repopulating Stem Cells Journal of Leukocyte Biology. May, 2003  |   Pubmed ID: 12714578 Stromal cell-derived factor-1 (SDF-1/CXCL12) enhances survival of myeloid progenitor cells. The two main questions addressed by us were whether these effects on the progenitors were direct-acting and if SDF-1/CXCL12 enhanced engrafting capability of competitive, repopulating mouse stem cells subjected to short-term ex vivo culture with other growth factors. SDF-1/CXCL12 had survival-enhancing/antiapoptosis effects on human bone marrow (BM) and cord blood (CB) and mouse BM colony-forming units (CFU)-granulocyte macrophage, burst-forming units-erythroid, and CFU-granulocyte-erythroid-macrophage-megakaryocyte with similar dose responses. The survival effects were direct-acting, as assessed on colony formation by single isolated human BM and CB CD34(+++) cells. Effects were mediated through CXCR4 and G(alpha)i proteins. Moreover, SDF-1/CXCL12 greatly enhanced the engrafting capability of mouse long-term, marrow-competitive, repopulating stem cells cultured ex vivo with interleukin-6 and steel factor for 48 h. These results extend information on the survival effects mediated through the SDF-1/CXCL12-CXCR4 axis and may be of relevance for ex vivo expansion and gene-transduction procedures.
• Basic Residues in the 37-loop of Activated Protein C Modulate Inhibition by Protein C Inhibitor but Not by Alpha(1)-antitrypsin Biochimica Et Biophysica Acta. Jun, 2003  |   Pubmed ID: 12818196 The role of lysines 37-39 (chymotrypsin numbering) in the 37-loop of the serine protease activated protein C (APC) was studied by expressing acidic and neutral recombinant APC (rAPC) mutants. Activity of the APC mutants was assessed using human plasma and plasma-purified and recombinant derivatives of protein C inhibitor (PCI; also known as plasminogen activator inhibitor-3) and alpha(1)-antitrypsin, with and without heparin. The catalytic properties of the mutants to small peptidyl substrates were essentially the same as wild-type rAPC (wt-rAPC), yet their plasma anticoagulant activities were diminished. Analysis of the rAPC-protease inhibitor complexes formed after addition of wt-rAPC and mutants to plasma revealed no change in the inhibition pattern by alpha(1)-antitrypsin but a reduction in mutant complex formation by PCI in the presence of heparin. Using purified serpins, we found that inhibition rates of the mutants were the same as wt-rAPC with alpha(1)-antitrypsin; however, PCI (plasma-derived and recombinant forms) inhibition rates of the acidic mutants were slightly faster than that of wt-rAPC without heparin. By contrast, PCI-heparin inhibition rates of the mutants were not substantially accelerated compared to wt-rAPC. The mutants had reduced heparin-binding properties compared to wt-rAPC. Molecular modeling of the PCI-APC complex with heparin suggests that heparin may function not only to bridge PCI to APC, but also to alleviate putative non-optimal intermolecular interactions. Our results suggest that the basic residues of the 37-loop of APC are involved in macromolecular substrate interactions and in heparin binding, and they influence inhibition by PCI (with or without heparin) but not by alpha(1)-antitrypsin, two important blood plasma serpins.
• Fanconi Anemia Type C and P53 Cooperate in Apoptosis and Tumorigenesis Blood. Dec, 2003  |   Pubmed ID: 12855557 Fanconi anemia (FA) is a recessive genomic instability syndrome characterized by developmental defects, progressive bone marrow failure, and cancer. FA is genetically heterogeneous, however; the proteins encoded by different FA loci interact functionally with each other and with the BRCA1, BRCA2, and ATM gene products. Although patients with FA are highly predisposed to the development of myeloid leukemia and solid tumors, the alterations in biochemical pathways responsible for the progression of tumorigenesis in these patients remain unknown. FA cells are hypersensitive to a range of genotoxic and cellular stresses that activate signaling pathways mediating apoptosis. Here we show that ionizing radiation (IR) induces modestly elevated levels of p53 in cells from FA type C (Fancc) mutant mice and that inactivation of Trp53 rescues tumor necrosis factor alpha-induced apoptosis in myeloid cells from Fancc-/- mice. Further, whereas Fancc-/- mice failed to form hematopoietic or solid malignancies, mice mutant at both Fancc and Trp53 developed tumors more rapidly than mice mutant at Trp53 alone. This shortened latency was associated with the appearance of tumor types that are found in patients with FA but not in mice mutant at Trp53 only. Collectively, these data demonstrate that p53 and Fancc interact functionally to regulate apoptosis and tumorigenesis in Fancc-deficient cells.
• Selective Enhancement of Multipotential Hematopoietic Progenitors in Vitro and in Vivo by IL-20 Blood. Nov, 2003  |   Pubmed ID: 12855566 In a search for novel growth factors, we discovered that human interleukin-20 (IL-20) enhanced colony formation by CD34+ multipotential progenitors. IL-20 had no effect on erythroid, granulocyte-macrophage, or megakaryocyte progenitors. IL-20 transgenic mice increased the numbers and cell cycling of multipotential but not other progenitors. IL-20 administration to normal mice significantly increased only multipotential progenitor cells, demonstrating that IL-20 significantly influences hematopoiesis, with specificity toward multipotential progenitors. This is the first cytokine with such specificity identified.
• Mobilization of Hematopoietic Progenitor Cells in Healthy Volunteers by AMD3100, a CXCR4 Antagonist Blood. Oct, 2003  |   Pubmed ID: 12855591 Stromal cell-derived factor 1 (SDF1/CXCL12) and its cognate receptor, CXCR4, play key regulatory roles in CD34+ cell trafficking. We investigated whether AMD3100, a selective CXCR4 antagonist, could mobilize hematopoietic progenitor cells from marrow to peripheral blood in healthy human volunteers. Initially, 10 persons each received a single dose of AMD3100 (80 microsubcutaneously), which induced rapid, generalized leukocytosis associated with an increase in peripheral blood CD34+ cells, representing pluripotent hematopoietic progenitors by in vitro colony-forming unit assays, from 3.8 +/- 0.5/microL to 20.7 +/- 3.5/microL at 6 hours. Subsequent dose-response studies showed a maximum increase in circulating CD34+ cells from 2.6 +/- 0.3/microL to 40.4 +/- 3.4/microL at 9 hours after 240 micro/kg AMD3100. Serial administration of AMD3100 (80 microg/kg/d for 3 days) resulted in consistent, reversible increases in peripheral blood CD34+ cells. AMD3100 was well tolerated and caused only mild, transient toxicity. These findings suggest potential clinical application of AMD3100 for CD34+ cell mobilization and collection for hematopoietic stem cell transplantation.
• Folate-liposome-mediated Antisense Oligodeoxynucleotide Targeting to Cancer Cells: Evaluation in Vitro and in Vivo Bioconjugate Chemistry. Jul-Aug, 2003  |   Pubmed ID: 12862426 The objective of this study was to investigate the use of folate-targeted liposomes for the delivery of encapsulated oligonucleotides to folate receptor (FR)-positive tumor cells in vitro and in vivo. This project involved the synthesis and biological evaluation of many folate-PEG-lipid conjugates, where the chemical form of the folate moiety (pteroate) and the length of the PEG linker chain were varied widely. Folate-targeted oligonucleotide-containing liposomes were prepared using conventional methods, and the extent of cell uptake was evaluated using, among others, the FR positive KB cell line. Oligonucleotide-loaded folate-targeted liposomes were found to rapidly associate with the KB cells, and saturation was typically reached within the first hour of incubation at 37 degrees C. Nearly 100,000 liposomes per cell were bound or internalized at saturation. Importantly, cell association was blocked by a large excess folic acid, thus reflecting the FR-specific nature of the cell interaction. Full targeting potential was achieved with PEG linkers as low as 1000 in molecular weight, and pteroates bearing glycine or gamma-aminobutyryl residues juxtaposed to the pteroic acid moiety were also effective for targeting, provided that a terminal cysteine moiety was present at the distal end of the PEG chain for added hydrophilicity. When tested in vivo, folate-targeted liposomes were found to deliver approximately 1.8-fold more oligonucleotide to the livers of nude mice (relative to the nontargeted PEG-containing formulations); however, no improvement in KB tumor uptake was observed. We conclude from these results that folate liposomes can effectively deliver oligonucleotides into folate receptor-bearing cells in vitro, but additional barriers exist in vivo that prevent or decrease effective tumor uptake and retention.
• Thrombomodulin Enhances the Reactivity of Thrombin with Protein C Inhibitor by Providing Both a Binding Site for the Serpin and Allosterically Modulating the Activity of Thrombin The Journal of Biological Chemistry. Sep, 2003  |   Pubmed ID: 12878585 Thrombomodulin (TM), or its epidermal growth factor-like domains 456 (TM456), enhances the catalytic efficiency of thrombin toward both protein C and protein C inhibitor (PCI) by 2-3 orders of magnitude. Structural and mutagenesis data have indicated that the interaction of basic residues of the heparin-binding exosite of protein C with the acidic residues of TM4 is partially responsible for the efficient activation of the substrate by the thrombin-TM456 complex. Similar to protein C, PCI has a basic exosite (H-helix) that constitutes the heparin-binding site of the serpin. To determine whether TM accelerates the reactivity of thrombin with PCI by providing a binding site for the H-helix of the serpin, an antithrombin (AT) mutant was constructed in which the H-helix of the serpin was replaced with the same region of PCI (AT-PCIH-helix). Unlike PCI, the H-helix of AT is negatively charged. It was discovered that TM456 slightly (
• Distinct Requirements for Stat4 and Stat6 in Hematopoietic Progenitor Cell Responses to Growth Factors and Chemokines Journal of Hematotherapy & Stem Cell Research. Aug, 2003  |   Pubmed ID: 12965077 Hematopoietic progenitor cell (HPC) homeostasis is critical in maintaining innate immunity and healing processes. Recently, we demonstrated that Th1 cells regulate HPC homeostasis, partly based on altered homeostasis in Stat4- and Stat6-deficient mice. To explore changes in HPC responsiveness in altered T helper cell environments, we directly examined growth factor-stimulated colony formation and chemokine-induced myelosuppression of HPC in Stat4- and Stat6-deficient bone marrow cells. Stat6-deficient cells have increased responses to the synergy between granulocyte-macrophage colony-stimulating factor (GM-CSF) and steel factor (SLF), compared to wild-type and Stat4-deficient cells. Increased responses are eliminated by in vivo depletion of CD4 cells. Whereas Stat6-deficient bone marrow cells respond to chemokine-mediated myelosuppression, Stat4-deficient bone marrow cells are refractory to the suppressive effects of chemokines. Thus, T helper cell development affects HPC homeostasis through several mechanisms, including the sensitivity to growth factor stimulation and chemokine suppression of HPC colony formation. Since Stat4 and Stat6 regulate opposing programs of T helper differentiation, there are distinct requirements for Stat4 and Stat6 in regulation of growth factor and chemokine responses of HPC.
• CD26 is Essential for Normal G-CSF-induced Progenitor Cell Mobilization As Determined by CD26-/- Mice Experimental Hematology. Nov, 2003  |   Pubmed ID: 14585379 In spite of the wide usage of mobilized peripheral blood hematopoietic stem and progenitor cells (HSC/HPC) for transplantation, the mechanism of granulocyte colony-stimulating factor (G-CSF)-induced HSC/HPC mobilization has yet to be fully determined. Our previous studies suggested that that G-CSF-induced mobilization may involve the extracellular peptidase CD26 (DPPIV/dipeptidylpeptidase IV). We set out to establish whether CD26 was an essential component of normal G-CSF-induced mobilization of HSC/HPC.
• Constitutive over Expression of Serine/threonine Protein Phosphatase 5 (PP5) Augments Estrogen-dependent Tumor Growth in Mice Cancer Letters. Nov, 2004  |   Pubmed ID: 15374638 Serine/threonine protein phosphatase 5 (PP5) appears to play an underappreciated role in the regulation of cellular proliferation. In estrogen-responsive cells, PP5 expression is stimulated by 17 beta-estradiol, and in a variety of p53 wild-type tumor cells the suppression of PP5 expression with ISIS 15534 inhibits growth. To further explore the relationship between PP5 and the development of human cancer, here we tested the effect of elevated PP5 expression on tumor growth using a mouse xenograph model and a stable MCF-7 cell line in which the expression of wild-type PP5 was placed under the control of tetracycline-off regulated transactivator and operator plasmids. In the xenograph model a modest two fold increase in PP5 protein levels significantly enhanced the growth rate of estrogen-dependent tumors, suggesting PP5 plays a positive role in tumor development.
• Comparative Proteomic Analysis of Human CD34+ Stem/progenitor Cells and Mature CD15+ Myeloid Cells Stem Cells (Dayton, Ohio). 2004  |   Pubmed ID: 15536191 Human CD34(+) cells, highly enriched for hematopoietic stem and progenitors, and CD15(+) cells, more terminally differentiated myeloid cells in blood, represent distinct maturation/differentiation stages. A proteomic approach was used to identify proteins differentially present in these two populations from human cord blood. Cytosolic proteins were extracted and subjected to two-dimensional gel electrophoresis followed by mass spectrometry. On average, 460 protein spots on each gel were detected; 112 and 15 proteins, respectively, were found to be differentially expressed or post-translationally modified in CD34(+) and CD15(+) cells. This suggests that CD34(+) cells have a relatively larger proteome than mature CD15(+) myeloid cells and production of many stem/progenitor cell-associated proteins ceases or is dramatically down-regulated as the CD34(+) cells undergo differentiation. Of approximately 140 protein spots, 47 different proteins were positively identified by mass spectrometry and database search; these proteins belong to several functional categories, including cell signaling, transcription factors, cytoskeletal proteins, metabolism, protein folding, and vesicle trafficking. Multiple heat shock proteins and chaperones, as well as proteins important for intracellular trafficking, were predominantly present in CD34(+) cells. Most of the identified proteins in CD34(+) cells are expressed in germ cell tumors, as well as in embryonal carcinoma and neuroblastoma. Approximately eight novel proteins, whose functions are unknown, were identified. This study presents, for the first time, global cellular protein expression patterns in human CD34(+) and CD15(+) cells, which should help to better understand intracellular processes involved in myeloid differentiation and add insight into the functional capabilities of these distinct cell types.
• Leukocytosis and Mobilization of CD34+ Hematopoietic Progenitor Cells by AMD3100, a CXCR4 Antagonist Supportive Cancer Therapy. Apr, 2004  |   Pubmed ID: 18628138 Stromal cell-derived factor-1 (SDF-1/CXCL12) plays a key regulatory role in the trafficking of hematopoietic cells. AMD3100 is a specific antagonist of the binding of SDF-1 to its receptor, CXCR4. This phase I study assessed the hematological effects, pharmacokinetics, and safety of administration of AMD3100 to 32 healthy volunteers, including its ability to mobilize CD34+ hematopoietic progenitor cells. A generalized leukocytosis occurred after a single subcutaneous injection of AMD3100 (80 microg/kg) resulting in a maximum white blood cell count of 19.49 +/- 1.27 x 103/microL (mean +/- SEM) at 6 hours. No changes were observed in erythrocyte or platelet counts. Circulating CD34+ cells increased 5-fold after administration of AMD3100 at 80 mug/kg and 15.5-fold in response to AMD3100 at 240 mug/kg, both at 9 hours after injection. Myeloid progenitor cells-colony forming unit granulocytemacrophage (CFU-GM); CFU-granulocyte, eosinophil, monocyte, megakaryocyte (CFU-GEMM); and burst forming units-erythroid showed similar increases in mobilization to the blood with increasing doses of AMD3100. The mobilized cells were in a slow or noncycling state as determined by in vitro high specific activity of 3H-thymidine. Pharmacokinetic studies showed a near linear increase in peak drug levels with increasing doses and nearly complete elimination of the drug by 24 hours. AMD3100 was well tolerated with only mild and transient toxicities (injection site erythema, headache, paresthesia, nausea, and abdominal distension) observed. These observations suggest that AMD3100 may be a clinically useful agent for hematopoietic progenitor cell mobilization.
• Characterization of Recombinant Human Protein C Inhibitor Expressed in Escherichia Coli Biochimica Et Biophysica Acta. Apr, 2005  |   Pubmed ID: 15752693 The serine protease inhibitor (serpin) protein C inhibitor (PCI; also named plasminogen activator inhibitor-3) regulates serine proteases in hemostasis, fibrinolysis, and reproduction. The biochemical activity of PCI is not fully defined partly due to the lack of a convenient expression system for active rPCI. Using pET-15b plasmid, Ni(2+)-chelate and heparin-Sepharose affinity chromatography steps, we describe here the expression, purification and characterization of wild-type recombinant (wt-rPCI) and two inactive mutants, R354A (P1 residue) and T341R (P14 residue), expressed in Escherichia coli. Wild-type rPCI, but not the two mutants, formed a stable bimolecular complex with thrombin, activated protein C and urokinase. In the absence of heparin, wt-rPCI-thrombin, -activated protein C, and -urokinase inhibition rates were 56.7, 3.4, and 2.3 x 10(4) M(-1) min(-1), respectively, and the inhibition rates were accelerated 25-, 71-, and 265-fold in the presence of 10 mug/mL heparin for each respective inhibition reaction. The stoichiometry of inhibition (SI) for wt-rPCI-thrombin was 2.0, which is comparable to plasma-derived PCI. The present report describes for the first time the expression and characterization of recombinant PCI in a bacterial expression system and demonstrates the feasibility of using this system to obtain adequate amounts of biologically active rPCI for future structure-function studies.
• Temporal Excitation Properties of Paresthesias Evoked by Thalamic Microstimulation Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology. May, 2005  |   Pubmed ID: 15826866 The neuronal elements mediating the effects of deep brain stimulation (DBS) are unknown. The objective was to determine the strength-duration properties of the neuronal elements that mediate paresthesias evoked by thalamic microstimulation.
• Rapid Mobilization of Murine and Human Hematopoietic Stem and Progenitor Cells with AMD3100, a CXCR4 Antagonist The Journal of Experimental Medicine. Apr, 2005  |   Pubmed ID: 15837815 Improving approaches for hematopoietic stem cell (HSC) and hematopoietic progenitor cell (HPC) mobilization is clinically important because increased numbers of these cells are needed for enhanced transplantation. Chemokine stromal cell derived factor-1 (also known as CXCL12) is believed to be involved in retention of HSCs and HPCs in bone marrow. AMD3100, a selective antagonist of CXCL12 that binds to its receptor, CXCR4, was evaluated in murine and human systems for mobilizing capacity, alone and in combination with granulocyte colony-stimulating factor (G-CSF). AMD3100 induced rapid mobilization of mouse and human HPCs and synergistically augmented G-CSF-induced mobilization of HPCs. AMD3100 also mobilized murine long-term repopulating (LTR) cells that engrafted primary and secondary lethally-irradiated mice, and human CD34(+) cells that can repopulate nonobese diabetic-severe combined immunodeficiency (SCID) mice. AMD3100 synergized with G-CSF to mobilize murine LTR cells and human SCID repopulating cells (SRCs). Human CD34(+) cells isolated after treatment with G-CSF plus AMD3100 expressed a phenotype that was characteristic of highly engrafting mouse HSCs. Synergy of AMD3100 and G-CSF in mobilization was due to enhanced numbers and perhaps other characteristics of the mobilized cells. These results support the hypothesis that the CXCL12-CXCR4 axis is involved in marrow retention of HSCs and HPCs, and demonstrate the clinical potential of AMD3100 for HSC mobilization.
• Dermal Delivery of Topically Applied Oligonucleotides Via Follicular Transport in Mouse Skin The Journal of Investigative Dermatology. May, 2005  |   Pubmed ID: 15854038 Antisense oligodeoxynucleotides formulated in cream preparations are being examined in the clinic as topical therapy for psoriasis. To produce their intended anti-inflammatory effects, these large anionic molecules must penetrate the stratum corneum and reach the living epidermis and dermis. A topically applied phosphorothioate antisense oligonucleotide targeted to intercellular adhesion molecule-1 recently was shown to modulate cytokine-inducible target gene expression in engrafted human skin. In this study, we examined the route of entry into mouse skin of fluorochrome-tagged or naked second-generation 2'-O-methoxyethyl-modified oligonucleotides that react specifically with an antibody, using topical cream-based formulations. In hairless mouse skin, immunohistochemical analysis and fluorescence microscopy were unable to detect the presence of oligonucleotide in the epidermis or dermis following topical application although immunostaining was associated with the stratum corneum and fluorescein isothiocyanate-labeled oligonucleotide was observed in hair follicles. Kinetic analysis of oligonucleotide topically applied to hair-clipped BALB/c mouse skin showed early follicular localization, diffusion of oligonucleotide from the mid-follicle, and subsequent dermal accumulation. Saline formulation resulted in oligonucleotide remaining within the hair follicle. These results suggest that oligonucleotide penetration in skin involves a follicular route and further, that topical oligonucleotide therapy may be particularly well suited for altering physiology within the hair follicle and related structures.
• Protein C Inhibitor (plasminogen Activator Inhibitor-3) Expression in the CWR22 Prostate Cancer Xenograft Experimental and Molecular Pathology. Aug, 2005  |   Pubmed ID: 15878512 The serine protease inhibitor (serpin) protein C inhibitor (PCI) has been found in the prostate and possibly is a marker to distinguish normal prostate, benign prostatic hyperplasia, and prostate cancer. In this study, we assessed PCI expression in normal, hyperplastic, and malignant prostatic tissues, prostate cancer cell lines, and the CWR22 prostate cancer xenograft model that allowed us to study PCI expression and its regulation in response to androgens. By Northern blot, immunohistochemistry, and in situ hybridization, we found that PCI was expressed in both benign and malignant prostate tissues. Protein C inhibitor was expressed in both androgen-independent (PC-3) and androgen-dependent (LNCaP) prostate cancer cell lines. Furthermore, PCI was detected in all CWR22 tumor samples (androgen dependent, 6 days post-castration, 12 days post-castration followed by 72 h of testosterone treatment, and recurrent CWR22 tumor), although expression of the mature forms of both prostate-specific antigen (PSA) and its homolog, kallikrein 2 (hK2), was clearly androgen-dependent. These results suggest that PCI expression is not regulated by androgens and that PCI is unlikely to be a tumor suppressor gene, but also that PCI may be involved in regulating key serine proteases involved in metastatic prostate disease.
• Identification of a Massive Reserve of Hematopoietic Progenitors in Mice Stem Cells and Development. Apr, 2005  |   Pubmed ID: 15910237 Previous studies have demonstrated that mice null (-/-) for either CD34 or c-mpl are viable and have greatly decreased numbers of multipotential (CFU-Mix), erythroid (BFU-E), and granulocytemacrophage (CFU-GM) progenitor cells in the bone marrow (BM), spleen (Spl) and peripheral blood (PB), without noticeable decreases in the nucleated cellularity of these organs. To evaluate the significance of these two proteins further, mice null for both CD34 and c-mpl were assessed for hematopoietic progenitor cells (HPC) and nucleated cellularity and compared with these cells in CD34-/- and c-mpl-/- mice. The following progenitors were assessed: CFU-GM, BFU-E, CFU-Mix with an erythroid component, CFU-Mix with erythroid and megakaryocyte components, nonerythroid CFU with a megakaryocyte (Meg) component and pure CFU-Meg. Results demonstrated significant decreases in progenitors in the BM of dual CD34/c-mpl-/- mice compared to decreases from CD34-/- or c-mpl-/- mice; progenitor numbers in CD34/c-mpl-/- mice were decreased by 83-99.3% compared to that in wild-type littermate control mice. Decreases in progenitors in spleens of c-mpl-/- mice (89-96%) were more drastic than those of CD34-/- mice (50-78%) whereas those of dual CD34/c-mpl-/- mice were equal to or lower than that of c-mpl-/- mice (93-98%). Decreases in PB progenitors were seen in the c-mpl-/- and dual CD34/c-mpl-/- mice (75-90%). Whereas progenitor cells in BM, Spl and PB were drastically reduced in dual CD34/c-mpl-/- mice compared to controls, absolute numbers of nucleated cells in these organs were essentially not reduced. These studies demonstrate that CD34 and c-mpl have non-redundant effects on maintenance of steady-state hematopoiesis and highlight how few progenitor cells are required in steady-state conditions to populate and maintain the BM, Spl, and PB with nucleated cells.
• Stromal Cell-derived Factor-1/CXCL12 Selectively Counteracts Inhibitory Effects of Myelosuppressive Chemokines on Hematopoietic Progenitor Cell Proliferation in Vitro Stem Cells and Development. Apr, 2005  |   Pubmed ID: 15910246 A variety of cytokines and chemokines exert potent myelosuppressive effects that play a role in the maintenance of hematopoiesis, which, if unchecked, may result in pathological impairment of blood cell production. Processes that modulate these myelosuppressive effects are not well defined. Here we demonstrate that stromal cell-derived factor-1 (SDF-1/CXCL12), known for its ability to attract and to promote survival of hematopoietic progenitor cells (HPCs) and stem cells, blocks the effects of a broad range of myelosuppressive chemokines on proliferation of HPCs in vitro. The regulatory effects of SDF/CXCL12 on colony formation by mouse bone marrow granulocyte-macrophage (CFUGM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells were assessed. These cells were stimulated to proliferate by combinations of growth factors, such that responses of immature HPCs could be assessed. SDF-1/CXCL12 potently blocked myelosuppressive responses induced by CCL2/MCP-1, CCL3/MIP-1alpha, CCL19/CKbeta-11, CCL25/TECK, CXCL4/PF4, CXCL8/IL-8, CXCL10/IP-10, and XCL1/Lymphotactin. However, SDF/CDL12 did not influence myelosuppression induced by tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, transforming growth factor (TGF)-beta or the iron-binding proteins H-ferritin or lactoferrin (LF). LF, previously shown to suppress release of growth factors, is shown here to also suppress proliferation of immature subsets of HPCs. HPCs from marrows of mice expressing an SDF-1/CXCL12 transgene were insensitive to inhibition by SDF/CXCL12-sensitive myelosuppressive chemokines, but not to SDF/CCL12-insensitive cytokines (TNF-alpha, IFN-gamma, TGF-beta, H-Ferritin, or LF). Thus, SDF-1/CXCL12 differentially and selectively regulates suppression of HPC proliferation by chemokines. These effects may counter myelosuppressive effects of certain chemokines in vivo, where proliferation of HPCs must be sustained.
• Exploring Protein Function and Evolution Using Free Online Bioinformatics Tools Biochemistry and Molecular Biology Education : a Bimonthly Publication of the International Union of Biochemistry and Molecular Biology. Sep, 2005  |   Pubmed ID: 21638591
• The Use of MERLOT in Biochemistry and Molecular Biology Education Biochemistry and Molecular Biology Education : a Bimonthly Publication of the International Union of Biochemistry and Molecular Biology. Sep, 2005  |   Pubmed ID: 21638592 The referatory, Multimedia Educational Resources for Learning and Online Teaching (MERLOT), contains links to 1300 electronic teaching resources in biology and chemistry. Approximately 20% have been peer reviewed, and most have user comments or assignments attached. In addition to being a source of educational resources, the MERLOT project seeks to strengthen the educational community by providing peer review and recognition of quality electronic learning objects.
• Parkinson Disease: Pattern of Functional MR Imaging Activation During Deep Brain Stimulation of Subthalamic Nucleus--initial Experience Radiology. Apr, 2006  |   Pubmed ID: 16567487 To prospectively determine the pattern of functional magnetic resonance (MR) imaging activation at 3 T produced by deep brain stimulation (DBS) of subthalamic nucleus (STN) for treatment of Parkinson disease and to determine the safety of DBS electrode stimulation during functional MR imaging at 3 T.
• Retraction. Macrophage Inflammatory Protein-1alpha and Interferon-inducible Protein 10 Inhibit Synergistically Induced Growth Factor Stimulation of MAP Kinase Activity and Suppress Phosphorylation of Eukaryotic Initiation Factor 4E and 4E Binding Protein 1 Blood. Jun, 2006  |   Pubmed ID: 16754774
• The IL-17 Cytokine Family Members Are Inhibitors of Human Hematopoietic Progenitor Proliferation Blood. Jul, 2006  |   Pubmed ID: 16822904
• Synergistic Inhibition in Vivo of Bone Marrow Myeloid Progenitors by Myelosuppressive Chemokines and Chemokine-accelerated Recovery of Progenitors After Treatment of Mice with Ara-C Experimental Hematology. Aug, 2006  |   Pubmed ID: 16863913 Selected chemokines suppress proliferation of hematopoietic progenitor cells (HPCs) in vitro; some of these have demonstrated inhibition of myelopoiesis in vivo. Because myelosuppressive chemokines synergize in vitro with other myelosuppressive chemokines, we sought to determine whether additional chemokines active in vitro were myelosuppressive in vivo and whether combinations of myelosuppressive chemokines synergized in vivo to dampen myelopoiesis. We also evaluated three chemokines in vivo for myeloprotection against Ara-C-induced decreases in HPCs.
• Class II Transactivator-mediated Regulation of Major Histocompatibility Complex Class II Antigen Expression is Important for Hematopoietic Progenitor Cell Suppression by Chemokines and Iron-binding Proteins Experimental Hematology. Aug, 2006  |   Pubmed ID: 16863914 Iron-binding proteins H-ferritin (HF) and lactoferrin (LF), as well as chemokines, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma suppress hematopoietic progenitor cell (HPC) proliferation. Major histocompatibility complex (MHC) class II antigens have been associated with suppressive effects of HF and LF. Because the transcription factor class II transactivator (CIITA) regulates expression of MHC class II antigens, we evaluated influences of CIITA and MHC class II antigens on suppression of colony formation by murine bone marrow HPC in response to HF, LF, CC, and CXC chemokines, TNF-alpha, and IFN-gamma. We also evaluated hematopoiesis in mice deficient in both CIITA and MHC class II antigens (CIITA -/-), in mice deficient in MHC class II antigens but not in CIITA (MHC class II -/-), and in mice deficient in CIITA but not in MHC class II antigens (CIITA-IE).
• Clinical Response to Varying the Stimulus Parameters in Deep Brain Stimulation for Essential Tremor Movement Disorders : Official Journal of the Movement Disorder Society. Nov, 2006  |   Pubmed ID: 16972236 Deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus for essential tremor is sometimes limited by side effects. The mechanisms by which DBS alleviates tremor or causes side effects are unclear; thus, it is difficult to select stimulus parameters that maximize the width of the therapeutic window. The goal of this study was to quantify the impact on side effect intensity (SE), tremor amplitude, and the therapeutic window of varying stimulus parameters. Tremor amplitude and SE were recorded at 40 to 90 combinations of pulse width, frequency, and voltage across 14 thalami. Posterior variable inclusion probabilities indicated that frequency and voltage were the most important predictors of both SE and tremor amplitude. The amount of tremor suppression achieved at frequencies of 90 to 100 Hz was not different from that at 160 to 170 Hz. However, the width of the therapeutic window decreased significantly and power consumption increased as frequency was increased above 90 to 100 Hz. Improved understanding of the relationships between stimulus parameters and clinical responses may lead to improved techniques of stimulus parameter adjustment.
• Cord Blood Stem and Progenitor Cells Methods in Enzymology. 2006  |   Pubmed ID: 17141066 Cord blood has served as a source of hematopoietic stem and progenitor cells for successful repopulation of the blood cell system in patients with malignant and nonmalignant disorders. It was information on these rare immature cells in cord blood that led to the first use of cord blood for transplantation. Further information on these cells and how they can be manipulated both in vitro and in vivo will likely enhance the utility and broadness of applicability of cord blood for treatment of human disease. This chapter reviews information on the clinical and biological properties of hematopoietic stem and progenitor cells, as well as the biology of endothelial progenitor cells, and serves as a source for the methods used to detect and quantitate these important functional cells. Specifically, methods are presented for enumerating human cord blood myeloid progenitor cells, including granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM or CFU-Mix) progenitors, and their replating potential; hematopoietic stem cells, as assessed in vitro for long-term culture-initiating cells (LTC-ICs), cobblestone area-forming cells (CAFCs), and myeloid-lymphoid-initiating cells (ML-ICs), and as assessed in vivo for nonobese diabetic (NOD)/severe combined immunodeficient (SCID) mouse repopulating cells (SRCs); and high and low proliferative potential endothelial progenitor cells (EPCs).
• Predicting the Effects of Deep Brain Stimulation with Diffusion Tensor Based Electric Field Models Medical Image Computing and Computer-assisted Intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention. 2006  |   Pubmed ID: 17354801 Deep brain stimulation (DBS) is an established therapy for the treatment of movement disorders, and has shown promising results for the treatment of a wide range of other neurological disorders. However, little is known about the mechanism of action of DBS or the volume of brain tissue affected by stimulation. We have developed methods that use anatomical and diffusion tensor MRI (DTI) data to predict the volume of tissue activated (VTA) during DBS. We co-register the imaging data with detailed finite element models of the brain and stimulating electrode to enable anatomically and electrically accurate predictions of the spread of stimulation. One critical component of the model is the DTI tensor field that is used to represent the 3-dimensionally anisotropic and inhomogeneous tissue conductivity. With this system we are able to fuse structural and functional information to study a relevant clinical problem: DBS of the subthalamic nucleus for the treatment of Parkinsons disease (PD). Our results show that inclusion of the tensor field in our model caused significant differences in the size and shape of the VTA when compared to a homogeneous, isotropic tissue volume. The magnitude of these differences was proportional to the stimulation voltage. Our model predictions are validated by comparing spread of predicted activation to observed effects of oculomotor nerve stimulation in a PD patient. In turn, the 3D tissue electrical properties of the brain play an important role in regulating the spread of neural activation generated by DBS.
• Subthalamic Nucleus Deep Brain Stimulation: Accurate Axonal Threshold Prediction with Diffusion Tensor Based Electric Field Models Conference Proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference. 2006  |   Pubmed ID: 17946452 Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become the therapy of choice for medically intractable Parkinson's Disease. However, the physiological mechanisms responsible for the therapeutic effects of DBS remain unknown, and quantitative understanding of the interaction between the electric field generated by DBS and the underlying neural tissue is lacking. Recently our group has developed various computational techniques to study the neural response to DBS. The goal of this study was to incrementally incorporate increasing levels of complexity into our computer models of STN DBS and address activation of the corticospinal tract (CST). Our model system was customized to an STN DBS patient and CST thresholds were calculated with electric field models that ranged from an electrostatic, homogeneous, isotropic model to one that explicitly incorporated the capacitance of the electrode-tissue interface, tissue encapsulation of the electrode, and diffusion-tensor based 3D tissue anisotropy and inhomogeneity. The model predictions were compared to clinical CST thresholds defined from electromyographic recordings from eight muscle groups in the arm and leg of the STN DBS patient. Coupled evaluation of the model and clinical data showed that accurate prediction of axonal thresholds required our most detailed model. In addition, the simplifications and assumptions typically utilized in neurostimulation models substantially overestimate neural activation.
• Mad2 is Required for Optimal Hematopoiesis: Mad2 Associates with C-Kit in MO7e Cells Blood. Mar, 2007  |   Pubmed ID: 17038523 Mitotic arrest deficiency 2 (Mad2) is a component of mitotic spindle checkpoint proteins and is essential for accurate chromosome segregation. We investigated a role for Mad2 in hematopoiesis using Mad2-haploinsufficient (Mad2+/-) mice. Mad2+/- bone marrow (BM) and spleen manifested decreased absolute numbers and cycling status of immature, but not mature, hematopoietic progenitor cells. Mad2+/- BM granulocyte-macrophage colony-forming units (CFU-GMs) did not manifest synergistic proliferation in response to stem cell factor (SCF) plus GM-CSF. The percentage of annexin V+ cells was higher in Mad2+/- than Mad2+/+c-Kit+lin- BM after culture with SCF and GM-CSF. However, no significant difference in phosphorylation of extracellular signal-related kinase (Erk1/2) at Thr202/Tyr204 and Akt at Ser473 between Mad2+/- and Mad2+/+BM c-Kit+lin- cells was observed. Immunoprecipitation assays performed in human MO7e cells demonstrated physical association of c-Kit with Mad2. Moreover, stimulation with SCF plus GM-CSF led to dissociation of Mad2 from c-Kit. Confocal microscopy demonstrated that Mad2 colocalized with c-Kit in the cytoplasm of MO7e cells. These results suggest that Mad2 is involved in synergistic growth of immature hematopoietic progenitor cells in response to SCF plus GM-CSF, effects that may be mediated via physical association of Mad2 with c-Kit.
• Patient-specific Analysis of the Volume of Tissue Activated During Deep Brain Stimulation NeuroImage. Jan, 2007  |   Pubmed ID: 17113789 Despite the clinical success of deep brain stimulation (DBS) for the treatment of movement disorders, many questions remain about its effects on the nervous system. This study presents a methodology to predict the volume of tissue activated (VTA) by DBS on a patient-specific basis. Our goals were to identify the intersection between the VTA and surrounding anatomical structures and to compare activation of these structures with clinical outcomes. The model system consisted of three fundamental components: (1) a 3D anatomical model of the subcortical nuclei and DBS electrode position in the brain, each derived from magnetic resonance imaging (MRI); (2) a finite element model of the DBS electrode and electric field transmitted to the brain, with tissue conductivity properties derived from diffusion tensor MRI; (3) VTA prediction derived from the response of myelinated axons to the applied electric field, which is a function of the stimulation parameters (contact, impedance, voltage, pulse width, frequency). We used this model system to analyze the effects of subthalamic nucleus (STN) DBS in a patient with Parkinson's disease. Quantitative measurements of bradykinesia, rigidity, and corticospinal tract (CST) motor thresholds were evaluated over a range of stimulation parameter settings. Our model predictions showed good agreement with CST thresholds. Additionally, stimulation through electrode contacts that improved bradykinesia and rigidity generated VTAs that overlapped the zona incerta/fields of Forel (ZI/H2). Application of DBS technology to various neurological disorders has preceded scientific characterization of the volume of tissue directly affected by the stimulation. Synergistic integration of clinical analysis, neuroimaging, neuroanatomy, and neurostimulation modeling provides an opportunity to address wide ranging questions on the factors linked with the therapeutic benefits and side effects of DBS.
• Enhanced Green Fluorescent Protein is a Nearly Ideal Long-term Expression Tracer for Hematopoietic Stem Cells, Whereas DsRed-express Fluorescent Protein is Not Stem Cells (Dayton, Ohio). Mar, 2007  |   Pubmed ID: 17138958 Validated gene transfer and expression tracers are essential for elucidating functions of mammalian genes. Here, we have determined the suitability and unintended side effects of enhanced green fluorescent protein (EGFP) and DsRed-Express fluorescent protein as expression tracers in long-term hematopoietic stem cells (HSCs). Retrovirally transduced mouse bone marrow cells expressing either EGFP or DsRed-Express in single or mixed dual-color cell populations were clearly discerned by flow cytometry and fluorescence microscopy. The results from in vivo competitive repopulation assays demonstrated that EGFP-expressing HSCs were maintained nearly throughout the lifespan of the transplanted mice and retained long-term multilineage repopulating potential. All mice assessed at 15 months post-transplantation were EGFP positive, and, on average, 24% total peripheral white blood cells expressed EGFP. Most EGFP-expressing recipient mice lived at least 22 months. In contrast, Discosoma sp. red fluorescent protein (DsRed)-expressing donor cells dramatically declined in transplant-recipient mice over time, particularly in the competitive setting, in which mixed EGFP- and DsRed-expressing cells were cotransplanted. Moreover, under in vitro culture condition favoring preservation of HSCs, purified EGFP-expressing cells grew robustly, whereas DsRed-expressing cells did not. Therefore, EGFP has no detectable deteriorative effects on HSCs, and is nearly an ideal long-term expression tracer for hematopoietic cells; however, DsRed-Express fluorescent protein is not suitable for these cells.
• AMD3100 and CD26 Modulate Mobilization, Engraftment, and Survival of Hematopoietic Stem and Progenitor Cells Mediated by the SDF-1/CXCL12-CXCR4 Axis Annals of the New York Academy of Sciences. Jun, 2007  |   Pubmed ID: 17360804 The chemokine stromal cell-derived factor-1 (SDF-1/CXCL12) and its receptor, CXCR4, are involved in a number of facets of the regulation of hematopoiesis at the level of hematopoietic stem (HSCs) and progenitor (HPCs) cells. Modulation of this ligand-receptor interaction may be of clinical utility. We now report that: (1) the CC chemokine, macrophage inflammatory protein-1alpha (MIP-1alpha/CCL3) synergizes with AMD3100 (an antagonist of the binding of SDF-1/CXCL12 to CXCR4) to rapidly mobilize HPCs to the blood of mice; moreover, the combination of granulocyte colony-stimulating factor (G-CSF) with AMD3100 and MIP-1alpha/CCL3, given in a specific sequence, mobilizes the greatest number of HPCs compared to any combination of two of these mobilizing agents; (2) pretreatment of recipient mice with Diprotin A, an inhibitor of CD26/Dipeptidylpeptidase IV (DPPIV), enhances the competitive HSCs repopulating capacity of untreated donor cells; (3) the survival-enhancing effects of SDF-1/CXCL12 on HPCs subjected in vitro to delayed addition of growth factors (GFs) are mediated in part through the cell cycle-related proteins p21(cip1/waf1) (as assessed using p21(cip1/waf1) -/- and +/+ mice) and Mad2 (using Mad2 +/- and +/+ mice); and (4) deletion of CD26/DPPIV on mouse bone marrow cells increases the survival-enhancing effects of SDF-1/CXCL12 on HPCs. These results demonstrate the means to increase the mobilization of HPCs, the engrafting capability of HSCs, and responsiveness of HPCs to the survival-enhancing activity of SDF-1/CXCL12, effects that may be of practical value.
• Regulation of Myeloid Progenitor Cell Proliferation/survival by IL-31 Receptor and IL-31 Experimental Hematology. Apr, 2007  |   Pubmed ID: 17379091 Interleukin (IL)-31 is a recently discovered helical cytokine. Its receptor consists of a ligand-specific IL-31 receptor (IL-31R) subunit and a receptor chain that is shared with Oncostatin M (OSM), called OSM-Rbeta. Because OSM-Rbeta-deficient animals have reduced hematopoietic progenitor cells (HPC) and OSM has effects on and is involved in homeostasis of HPC, we studied whether IL-31 and IL-31R play a role in hematopoiesis.
• A Role for Natural Killer T Cells and CD1d Molecules in Counteracting Suppression of Hematopoiesis in Mice Induced by Infection with Murine Cytomegalovirus Experimental Hematology. Apr, 2007  |   Pubmed ID: 17379092 Infection of immunocompromised patients with cytomegalovirus (CMV), such as that occurring in patients undergoing hematopoietic stem cell transplantation, is a serious clinical problem. CMV infection has been reported to suppress hematopoiesis. In immunocompetent hosts CMV is controlled initially by the innate immune system, with CD1d molecules and natural killer T (NKT) cells playing a role in the antiviral immune response in several model systems. We hypothesized that CD1d and NKT cells are involved in protection of the hematopoietic modulating effects of CMV, and that adoptive transfer of NKT cells would protect against these infection-induced effects.
• A Naturally Occurring Splice Variant of CXCL12/stromal Cell-derived Factor 1 is a Potent Human Immunodeficiency Virus Type 1 Inhibitor with Weak Chemotaxis and Cell Survival Activities Journal of Virology. Aug, 2007  |   Pubmed ID: 17507482 CXCL12/stromal cell-derived factor 1 is a member of the CXC family of chemokines that plays an important role in hematopoiesis and signals through CXCR4 and CXCR7. Two splice variants of human CXCL12 (CXCL12alpha and CXCL12beta) induce chemotaxis of CXCR4(+) cells and inhibit X4 infection. Recent studies described four other novel splice variants of human CXCL12; however, their antiviral activities were not investigated. We constructed and expressed all of the CXCL12 splice variants in Escherichia coli. Recombinant proteins were purified through a His affinity column, and their biological properties were analyzed. All six CXCL12 variants induced chemotaxis of CXCR4(+) and CXCR7(+) cell lines. Enhancement of survival and replating capacity of human hematopoietic progenitor cells were observed with CXCL12alpha, CXCL12beta, and CXCL12epsilon but not with the other variants. CXCL12gamma showed the greatest antiviral activity in X4 inhibition assays and the weakest chemotaxis activity through CXCR4. The order of potency in X4 inhibition assays was as follows: CXCL12gamma > CXCL12beta > CXCL12alpha > CXCL12theta > CXCL12epsilon > CXCL12delta. The order of anti-human immunodeficiency virus (HIV) activity was associated with the number of BBXB motifs present in each variant; the most potent inhibitor was CXCL12gamma, with five BBXB domains. The results suggest that the different C termini of CXCL12 variants may contain important molecular determinants for the observed differences in antiviral effects and other biological functions. These studies implicate CXCL12gamma as a potent HIV-1 entry inhibitor with significantly reduced chemotaxis activity and small or absent effects on progenitor cell survival or replating capacity, providing important insight into the structure-function relationships of CXCL12.
• Aberrant Regulation of Hematopoiesis by T Cells in BAZF-deficient Mice Molecular and Cellular Biology. Aug, 2007  |   Pubmed ID: 17526724 The BAZF (BCL-6b) protein is highly similar to the BCL-6 transcriptional repressor. While BCL-6 has been characterized extensively, relatively little is known about the normal function of BAZF. In order to understand the physiological role of BAZF, we created BAZF-deficient mice. Unlike BCL-6-deficient mice, BAZF-deficient mice are healthy and normal in size. However, BAZF-deficient mice have a hematopoietic progenitor phenotype that is almost identical to that of BCL-6-deficient mice. Compared to wild-type mice, both BAZF-deficient and BCL-6-deficient mice have greatly reduced numbers of cycling hematopoietic progenitor cells (HPC) in the BM and greatly increased numbers of cycling HPC in the spleen. In contrast to HPC from wild-type mice, HPC from BAZF-deficient and BCL-6-deficient mice are resistant to chemokine-induced myelosuppression and do not show a synergistic growth response to granulocyte-macrophage colony-stimulating factor plus stem cell factor. Depletion of CD8 T cells in BAZF-deficient mice reverses several of the hematopoietic defects in these mice. Since both BAZF- and BCL-6-deficient mice have defects in CD8 T-cell differentiation, we hypothesize that both BCL-6 and BAZF regulate HPC homeostasis by an indirect pathway involving CD8 T cells.
• Incidence, Risk Factors, and Prevention of Post-ERCP Pancreatitis Gastroenterology Clinics of North America. Jun, 2007  |   Pubmed ID: 17533078 Pancreatitis is the most common complication of endoscopic retrograde cholangiopancreatography (ERCP). Because of the potential risks and consequences of post-ERCP pancreatitis, considerable efforts have been made to define patient- and procedure-related factors that may be associated with an increased risk of this complication, along with determining interventions that can be done to reduce post-ERCP pancreatitis.
• TGF-beta Combined with M-CSF and IL-4 Induces Generation of Immune Inhibitory Cord Blood Dendritic Cells Capable of Enhancing Cytokine-induced Ex Vivo Expansion of Myeloid Progenitors Blood. Oct, 2007  |   Pubmed ID: 17585053 Tolerogenic dendritic cells (DCs) may be valuable in transplantation for silencing immune reaction. Macrophage colony-stimulating factor (M-CSF)/IL-4 induces differentiation of cord blood (CB) monocytes into DCs (M-DCs) with tolerogenic phenotype/function. We assessed whether factors produced by tolerogenic DCs could modulate hematopoiesis. TGF-beta1 added to CB M-DC cultures induced bona fide DC morphology (TGF-M-DCs), similar to that of DCs generated with TGF-beta and granulocyte-macrophage colony-stimulating factor (GM-CSF)/IL-4 (TGF-GM-DCs). Of conditioned media (CM) produced from TGF-M-DCs, TGF-GM-DCs, M-DCs, and GM-DCs, TGF-M-DC CM was the only one that enhanced SCF, Flt3 ligand, and TPO expansion of myeloid progenitor cells ex vivo. This effect was blocked by neutralizing anti-M-CSF Ab, but protein analysis of CM suggested that M-CSF alone was not manifesting enhanced expansion of myeloid progenitors. LPS-stimulated TGF-M-DCs induced T-cell tolerance/anergy as effectively as M-DCs. TGF-M-DCs secreted significantly lower concentrations of progenitor cell inhibitory cytokines and were less potent in activating T cells than TGF-GM-DCs. Functional differences between TGF-M-DCs and TGF-GM-DCs included enhanced responses to LPS-induced ERK, JNK, and P38 activation in TGF-M-DCs and their immune suppressive-skewed cytokine release profiles. TGF-M-DCs appear unique among culture-generated DCs in their capability for silencing immunity while promoting expansion of myeloid progenitors, events that may be of therapeutic value.
• Amplitude- and Frequency-dependent Changes in Neuronal Regularity Parallel Changes in Tremor With Thalamic Deep Brain Stimulation IEEE Transactions on Neural Systems and Rehabilitation Engineering : a Publication of the IEEE Engineering in Medicine and Biology Society. Jun, 2007  |   Pubmed ID: 17601188 The mechanisms by which deep brain stimulation (DBS) alleviates tremor remain unclear, but successful treatment can be achieved with properly selected frequency and amplitude. The clinical tremor response to thalamic DBS for essential tremor is dependent on the stimulation frequency and amplitude, and for high frequencies (> or = 90 Hz), increasing amplitude suppressed tremor, whereas for low frequencies (< 60 Hz), increasing amplitude aggravated tremor. We studied the effects of stimulation frequency and amplitude on the output of a population of intrinsically active model neurons to test the hypothesis that regularization of neuronal firing patterns is responsible for the clinical effectiveness of DBS. The firing patterns of model thalamocortical neurons were dependent on stimulation frequency and amplitude in a manner similar to the clinical tremor response. Above a critical frequency, increasing amplitude reduced the coefficient of variation (CV) of the neuronal firing pattern, whereas for low frequencies, increasing the amplitude increased the CV of neuronal activity. The correlation between the changes in tremor and the changes in the CV of neuronal firing supports the hypothesis that regularization of neuronal firing pattern during DBS is one of the mechanisms underlying the suppression of tremor.
• Pulse-to-pulse Changes in the Frequency of Deep Brain Stimulation Affect Tremor and Modeled Neuronal Activity Journal of Neurophysiology. Sep, 2007  |   Pubmed ID: 17634335 The effectiveness of deep brain stimulation (DBS) in relieving the symptoms of movement disorders is dependent on the average frequency of stimulation. However, no one has yet examined whether the effectiveness of DBS in relieving tremor is dependent on the pulse-to-pulse (instantaneous) frequency of DBS. We examined the effects of paired-pulse thalamic DBS on tremor in subjects with essential tremor and on the firing of model neurons in a biophysically based computational model of DBS. DBS with an average rate of 130 Hz was more effective at reducing tremor when pulses were evenly spaced than when there were large differences between intrapair and interpair pulse intervals. Similar correlations were observed in the firing patterns of model neurons: increasing the difference between the intrapair and interpair intervals rendered model neurons more likely to fire synchronous bursts, more likely to fire irregularly, and less likely to entrain to the stimulus. The tremor responses provide evidence that the pulse-to-pulse frequency of DBS, not just its average rate, plays an important role in DBS function. Modeling results also suggest that effective DBS overrides oscillatory pathological activity and replaces it with more regularized neuronal firing patterns.
• SDF-1/CXCL12 Enhances in Vitro Replating Capacity of Murine and Human Multipotential and Macrophage Progenitor Cells Stem Cells and Development. Aug, 2007  |   Pubmed ID: 17784832 Hematopoietic progenitor cells (HPCs) manifest a limited self-renewal capacity, as determined by a surrogate assay involving replating capacity of single colonies in vitro with generation of secondary colonies. Stromal cell-derived factor-1 (SDF-1/CXCL12), has been implicated in regulation of hematopoiesis through its modulation of hematopoietic stem cell (HSC) and HPC migration, homing, mobilization, and survival. We used bone marrow cells from SDF-1/CXCL12 transgenic and littermate control mice, and culture of normal mouse bone marrow and human cord blood cells plated in the presence or absence of recombinant SDF-1/CXCL12 to evaluate a role for SDF-1/CXCL12 in the replating capability in vitro of multipotential [colony-forming units (CFU)-GEMM] and macrophage (CFU-M) progenitor cells. Competitive repopulating capacity of mouse HSCs was assessed in lethally irradiated mice. Transgenic or exogenous SDF-1/CXCL12 significantly enhanced numbers of secondary colonies formed from primary CFU-GEMM or CFU-M colonies. In the limited setting of our in vivo studies, the SDF-1/CXCL12 transgene did not influence HSC competitive repopulation. However, the results suggest that SDF-1/CXCL12 enhances in vitro replating/self-renewal of HPCs, which may contribute to myelopoiesis in vivo. This information may be of value to ex vivo expansion of HPCs/HSCs.
• Mutation of the H-helix in Antithrombin Decreases Heparin Stimulation of Protease Inhibition Biochimica Et Biophysica Acta. Nov, 2007  |   Pubmed ID: 17905675 Blood clotting proceeds through the sequential proteolytic activation of a series of serine proteases, culminating in thrombin cleaving fibrinogen into fibrin. The serine protease inhibitors (serpins) antithrombin (AT) and protein C inhibitor (PCI) both inhibit thrombin in a heparin-accelerated reaction. Heparin binds to the positively charged D-helix of AT and H-helix of PCI. The H-helix of AT is negatively charged, and it was mutated to contain neutral or positively charged residues to see if they contributed to heparin stimulation or protease specificity in AT. To assess the impact of the H-helix mutations on heparin stimulation in the absence of the known heparin-binding site, negative charges were also introduced in the D-helix of AT. AT with both positively charged H- and D-helices showed decreases in heparin stimulation of thrombin and factor Xa inhibition by 10- and 5-fold respectively, a decrease in affinity for heparin sepharose, and a shift in the heparin template curve. In the absence of a positively charged D-helix, changing the H-helix from neutral to positively charged increased heparin stimulation of thrombin inhibition 21-fold, increased heparin affinity and restored a normal maximal heparin concentration for inhibition.
• A Method to Estimate the Spatial Extent of Activation in Thalamic Deep Brain Stimulation Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology. Sep, 2008  |   Pubmed ID: 18632304 The goal of this study was to develop, evaluate, and apply a method to quantify the unknown spatial extent of activation in deep brain stimulation (DBS) of the ventral intermedius nucleus (Vim) of the thalamus.
• A Model Predicting Optimal Parameters for Deep Brain Stimulation in Essential Tremor Journal of Clinical Neurophysiology : Official Publication of the American Electroencephalographic Society. Oct, 2008  |   Pubmed ID: 18791473 In nine patients with essential tremor (14 thalami), the authors varied frequency, voltage, and pulsewidth of thalamic deep brain stimulation, and quantified postural tremor. Low frequency stimulation aggravated tremor; the effect increased with increasing voltage. High frequency stimulation had a U-shaped relation to voltage, with minimum tremor at an optimal voltage characteristic of the individual thalamus and increases in voltage beyond the optimum reduced tremor suppression.Based on the hypothesis that tremor response to deep brain stimulation resulted from two competing processes, the authors successfully modeled the relationship of tremor to voltage and frequency of stimulation using a mathematical model. The optimum voltage predicted by the model agreed with the empirically measured value. Moreover, the model made accurate predictions at high stimulation frequency based on measurements made at low stimulation frequency.Our results indicate there is an optimal voltage for tremor suppression by thalamic deep brain stimulation in most patients with essential tremor. The optimum varies across patients, and this is related to electrode position. A mathematical model based on "competing processes" successfully predicts optimum voltage in individual patients. This supports a competing processes model of deep brain stimulation effects.
• Automated 3-dimensional Brain Atlas Fitting to Microelectrode Recordings from Deep Brain Stimulation Surgeries Stereotactic and Functional Neurosurgery. 2009  |   Pubmed ID: 19556832 Deep brain stimulation (DBS) surgeries commonly rely on brain atlases and microelectrode recordings (MER) to help identify the target location for electrode implantation. We present an automated method for optimally fitting a 3-dimensional brain atlas to intraoperative MER and predicting a target DBS electrode location in stereotactic coordinates for the patient.
• Targeted Disruption of Zfp36l2, Encoding a CCCH Tandem Zinc Finger RNA-binding Protein, Results in Defective Hematopoiesis Blood. Sep, 2009  |   Pubmed ID: 19633199 Members of the tristetraprolin family of tandem CCCH finger proteins can bind to AU-rich elements in the 3'-untranslated region of mRNAs, leading to their deadenylation and subsequent degradation. Partial deficiency of 1 of the 4 mouse tristetraprolin family members, Zfp36l2, resulted in complete female infertility because of early embryo death. We have now generated mice completely deficient in the ZFP36L2 protein. Homozygous Zfp36l2 knockout (KO) mice died within approximately 2 weeks of birth, apparently from intestinal or other hemorrhage. Analysis of peripheral blood from KO mice showed a decrease in red and white cells, hemoglobin, hematocrit, and platelets. Yolk sacs from embryonic day 11.5 (E11.5) Zfp36l2 KO mice and fetal livers from E14.5 KO mice gave rise to markedly reduced numbers of definitive multilineage and lineage-committed hematopoietic progenitors. Competitive reconstitution experiments demonstrated that Zfp36l2 KO fetal liver hematopoietic stem cells were unable to adequately reconstitute the hematopoietic system of lethally irradiated recipients. These data establish Zfp36l2 as a critical modulator of definitive hematopoiesis and suggest a novel regulatory pathway involving control of mRNA stability in the life cycle of hematopoietic stem and progenitor cells.
• Relationship Building Blocks The Journal of School Health. Oct, 2009  |   Pubmed ID: 19751312
• EUS-guided Rendezvous for the Treatment of Pancreaticopleural Fistula in a Patient with Chronic Pancreatitis and Pancreas Pseudodivisum Gastrointestinal Endoscopy. Mar, 2010  |   Pubmed ID: 19892329
• Does Displaying the Class Results Affect Student Discussion During Peer Instruction? CBE Life Sciences Education. 2010  |   Pubmed ID: 20516358 The use of personal response systems, or clickers, is increasingly common in college classrooms. Although clickers can increase student engagement and discussion, their benefits also can be overstated. A common practice is to ask the class a question, display the responses, allow the students to discuss the question, and then collect the responses a second time. In an introductory biology course, we asked whether showing students the class responses to a question biased their second response. Some sections of the course displayed a bar graph of the student responses and others served as a control group in which discussion occurred without seeing the most common answer chosen by the class. If students saw the bar graph, they were 30% more likely to switch from a less common to the most common response. This trend was more pronounced in true/false questions (38%) than multiple-choice questions (28%). These results suggest that observing the most common response can bias a student's second vote on a question and may be misinterpreted as an increase in performance due to student discussion alone.
• Patient-specific Models of Deep Brain Stimulation: Influence of Field Model Complexity on Neural Activation Predictions Brain Stimulation. Apr, 2010  |   Pubmed ID: 20607090 Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become the surgical therapy of choice for medically intractable Parkinson's disease. However, quantitative understanding of the interaction between the electric field generated by DBS and the underlying neural tissue is limited. Recently, computational models of varying levels of complexity have been used to study the neural response to DBS. The goal of this study was to evaluate the quantitative impact of incrementally incorporating increasing levels of complexity into computer models of STN DBS. Our analysis focused on the direct activation of experimentally measureable fiber pathways within the internal capsule (IC). Our model system was customized to an STN DBS patient and stimulation thresholds for activation of IC axons were calculated with electric field models that ranged from an electrostatic, homogenous, isotropic model to one that explicitly incorporated the voltage-drop and capacitance of the electrode-electrolyte interface, tissue encapsulation of the electrode, and diffusion-tensor based 3D tissue anisotropy and inhomogeneity. The model predictions were compared to experimental IC activation defined from electromyographic (EMG) recordings from eight different muscle groups in the contralateral arm and leg of the STN DBS patient. Coupled evaluation of the model and experimental data showed that the most realistic predictions of axonal thresholds were achieved with the most detailed model. Furthermore, the more simplistic neurostimulation models substantially overestimated the spatial extent of neural activation.
• Engineered Antifouling Microtopographies: the Role of Reynolds Number in a Model That Predicts Attachment of Zoospores of Ulva and Cells of Cobetia Marina Biofouling. Aug, 2010  |   Pubmed ID: 20706891 A correlation between the attachment density of cells from two phylogenetic groups (prokaryotic Bacteria and eukaryotic Plantae), with surface roughness is reported for the first time. The results represent a paradigm shift in the understanding of cell attachment, which is a critical step in the biofouling process. The model predicts that the attachment densities of zoospores of the green alga, Ulva, and cells of the marine bacterium, Cobetia marina, scale inversely with surface roughness. The size and motility of the bacterial cells and algal spores were incorporated into the attachment model by multiplying the engineered roughness index (ERI(II)), which is a representation of surface energy, by the Reynolds number (Re) of the cells. The results showed a negative linear correlation of normalized, transformed attachment density for both organisms with ERI(II) x Re (R(2) = 0.77). These studies demonstrate for the first time that organisms respond in a uniform manner to a model, which incorporates surface energy and the Reynolds number of the organism.
• Adipose Stem Cell Treatment in Mice Attenuates Lung and Systemic Injury Induced by Cigarette Smoking American Journal of Respiratory and Critical Care Medicine. Jan, 2011  |   Pubmed ID: 20709815 Adipose-derived stem cells express multiple growth factors that inhibit endothelial cell apoptosis, and demonstrate substantial pulmonary trapping after intravascular delivery.
• SIRT1 Deficiency Compromises Mouse Embryonic Stem Cell Hematopoietic Differentiation, and Embryonic and Adult Hematopoiesis in the Mouse Blood. Jan, 2011  |   Pubmed ID: 20966168 SIRT1 is a founding member of a sirtuin family of 7 proteins and histone deacetylases. It is involved in cellular resistance to stress, metabolism, differentiation, aging, and tumor suppression. SIRT1(-/-) mice demonstrate embryonic and postnatal development defects. We examined hematopoietic and endothelial cell differentiation of SIRT1(-/-) mouse embryonic stem cells (ESCs) in vitro, and hematopoietic progenitors in SIRT1(+/+)(+/-), and (-/-) mice. SIRT1(-/-) ESCs formed fewer mature blast cell colonies. Replated SIRT1(-/-) blast colony-forming cells demonstrated defective hematopoietic potential. Endothelial cell production was unaltered, but there were defects in formation of a primitive vascular network from SIRT1(-/-)-derived embryoid bodies. Development of primitive and definitive progenitors derived from SIRT1(-/-) ESCs were also delayed and/or defective. Differentiation delay/defects were associated with delayed capacity to switch off Oct4, Nanog and Fgf5 expression, decreased β-H1 globin, β-major globin, and Scl gene expression, and reduced activation of Erk1/2. Ectopic expression of SIRT1 rescued SIRT1(-/-) ESC differentiation deficiencies. SIRT1(-/-) yolk sacs manifested fewer primitive erythroid precursors. SIRT1(-/-) and SIRT1(+/-) adult marrow had decreased numbers and cycling of hematopoietic progenitors, effects more apparent at 5%, than at 20%, oxygen tension, and these progenitors survived less well in vitro under conditions of delayed growth factor addition. This suggests a role for SIRT1 in ESC differentiation and mouse hematopoiesis.
• Probabilistic Analysis of Activation Volumes Generated During Deep Brain Stimulation NeuroImage. Feb, 2011  |   Pubmed ID: 20974269 Deep brain stimulation (DBS) is an established therapy for the treatment of Parkinson's disease (PD) and shows great promise for the treatment of several other disorders. However, while the clinical analysis of DBS has received great attention, a relative paucity of quantitative techniques exists to define the optimal surgical target and most effective stimulation protocol for a given disorder. In this study we describe a methodology that represents an evolutionary addition to the concept of a probabilistic brain atlas, which we call a probabilistic stimulation atlas (PSA). We outline steps to combine quantitative clinical outcome measures with advanced computational models of DBS to identify regions where stimulation-induced activation could provide the best therapeutic improvement on a per-symptom basis. While this methodology is relevant to any form of DBS, we present example results from subthalamic nucleus (STN) DBS for PD. We constructed patient-specific computer models of the volume of tissue activated (VTA) for 163 different stimulation parameter settings which were tested in six patients. We then assigned clinical outcome scores to each VTA and compiled all of the VTAs into a PSA to identify stimulation-induced activation targets that maximized therapeutic response with minimal side effects. The results suggest that selection of both electrode placement and clinical stimulation parameter settings could be tailored to the patient's primary symptoms using patient-specific models and PSAs.
• Hematopoietic Stem/progenitor Cells, Generation of Induced Pluripotent Stem Cells, and Isolation of Endothelial Progenitors from 21- to 23.5-year Cryopreserved Cord Blood Blood. May, 2011  |   Pubmed ID: 21393480 Cryopreservation of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) is crucial for cord blood (CB) banking and transplantation. We evaluated recovery of functional HPC cryopreserved as mononuclear or unseparated cells for up to 23.5 years compared with prefreeze values of the same CB units. Highly efficient recovery (80%-100%) was apparent for granulocyte-macrophage and multipotential hematopoietic progenitors, although some collections had reproducible low recovery. Proliferative potential, response to multiple cytokines, and replating of HPC colonies was extensive. CD34(+) cells isolated from CB cryopreserved for up to 21 years had long-term (≥ 6 month) engrafting capability in primary and secondary immunodeficient mice reflecting recovery of long-term repopulating, self-renewing HSCs. We recovered functionally responsive CD4(+) and CD8(+) T lymphocytes, generated induced pluripotent stem (iPS) cells with differentiation representing all 3 germ cell lineages in vitro and in vivo, and detected high proliferative endothelial colony forming cells, results of relevance to CB biology and banking.
• TIP110/p110nrb/SART3/p110 Regulation of Hematopoiesis Through CMYC Blood. May, 2011  |   Pubmed ID: 21447833 Intracellular factors are involved in and essential for hematopoiesis. HIV-1 Tat-interacting protein of 110 kDa (TIP110; p110(nrb)/SART3/p110) is an RNA-binding nuclear protein implicated in the regulation of HIV-1 gene and host gene transcription, pre-mRNA splicing, and cancer immunology. In the present study, we demonstrate a role for TIP110 in the regulation of hematopoiesis. TIP110 was expressed in human CD34(+) cells and decreased with differentiation of CD34(+) cells. TIP110 mRNA was also expressed in phenotyped mouse marrow hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). Using TIP110 transgenic (TIP110(TG)) and haploinsufficient (TIP110(+/-)) mice, we found that increased TIP110 expression enhanced HPC numbers, survival, and cell cycling, whereas decreased TIP110 expression had the opposite effects. Moreover, TIP110(+/-) bone marrow HPCs responded more effectively, and TIP110(TG) HPCs less effectively, than those of wild-type control mice to recovery from the cell-cycle-active drug 5-fluorouracil (5-FU). Unexplained sex differences were noted in HSC competitive repopulating ability, but not HPC numbers, in TIP110(TG) mice. Intracellularly, TIP110 regulated CMYC and GATA2 expression at the transcriptional level, and TIP110 and CMYC reciprocally regulated the expression of each other. These results demonstrate a role for TIP110 in the regulation of hematopoiesis, effects that are likely linked to TIP110 regulation of CMYC.
• STAT3-dependent IL-21 Production from T Helper Cells Regulates Hematopoietic Progenitor Cell Homeostasis Blood. Jun, 2011  |   Pubmed ID: 21505191 The contribution of specific cell types to the production of cytokines that regulate hematopoiesis is still not well defined. We have previously identified T cell-dependent regulation of hematopoietic progenitor cell (HPC) numbers and cycling. In this report, we demonstrated that HPC activity is decreased in mice with STAT3-deficient T cells, a phenotype that is not because of decreased expression of IL-17 or RORγt. STAT3 expression in T cells was required for IL-21 production by multiple T helper subsets, and neutralization of IL-21 resulted in decreased HPC activity identical to that in mice with STAT3-deficient T cells. Importantly, injection of IL-21 rescued HPC activity in mice with STAT3-deficient T cells. Thus, STAT3-dependent IL-21 production in T cells is required for HPC homeostasis.
• Endoscopic Ultrasound-guided Fine-needle Aspiration of Metastases to the Pancreas: A Study of 25 Cases CytoJournal. 2011  |   Pubmed ID: 21713016 Metastases to the pancreas are an uncommon cause of pancreatic masses seen on endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA). The purpose of this study is to retrospectively review the cytomorphology, clinical findings, and results of ancillary studies in a large series of these unusual cases.
• Return of Bradykinesia After Subthalamic Stimulation Ceases: Relationship to Electrode Location Experimental Neurology. Oct, 2011  |   Pubmed ID: 21736878 In 20 subjects we quantified the rate at which subthalamic nucleus deep brain stimulation effects on Parkinson's bradykinesia "washed-out" after stimulation ceased. We found that wash-out was a two-step process, consisting of an initial fast decrease in stimulation's therapeutic effect, followed by a further, slow decline. Moreover, the relative contribution of the fast and slow components differed between patients. Finally, we found that lateral stimulation caused more of the fast-decaying component, while medial stimulation caused more of the slow-decaying component. This implies the existence of at least two separate mechanisms by which subthalamic nucleus deep brain stimulation improves bradykinesia, associated with activation of spatially separate zones in the vicinity of the subthalamic nucleus.
• Engineered Antifouling Microtopographies: Kinetic Analysis of the Attachment of Zoospores of the Green Alga Ulva to Silicone Elastomers Biofouling. Sep, 2011  |   Pubmed ID: 21882899 Microtopography has been demonstrated as an effective deterrent to biofouling. The majority of published studies are fixed-time assays that raise questions regarding the kinetics of the attachment process. This study investigated the time-dependent attachment density of zoospores of Ulva, in a laboratory assay, on a micropatterned and smooth silicone elastomer. The attachment density of zoospores was reduced on average 70-80% by the microtopography relative to smooth surfaces over a 4 h exposure. Mapping the zoospore locations on the topography revealed that they settled preferentially in specific, recessed areas of the pattern. The kinetic data fit, with high correlation (r(2) > 0.9), models commonly used to describe the adhesion of bacteria to surfaces. The grouping of spores on the microtopography indicated that the pattern inhibited the ability of attached spores to recruit neighbors. This study demonstrates that the antifouling mechanism of topographies may involve disruption of the cooperative effects exhibited by fouling organisms such as Ulva.
• Cyclin Dependent Kinase Inhibitors Differentially Modulate Synergistic Cytokine Responsiveness of Hematopoietic Progenitor Cells Stem Cells and Development. Jul, 2012  |   Pubmed ID: 21936707 Cyclin dependent kinase inhibitors (CDKIs) influence proliferation of hematopoietic progenitor cells (HPCs), but little is known of how they influence proliferative responsiveness of HPCs to colony stimulating factors (CSFs), alone and in combination with other hematopoietically active factors, such as the potent co-stimulating cytokine stem cell factor (SCF), or inhibition by myelosuppressive chemokines. Using mice with deletions in p18(INK4c), p21(CIP1/WAF1), or p27(KIP1) genes, and in mice with double gene deletions for either p18/p21 or p18/p27, we determined effects of absence of these CDKIs and their interactions on functional HPC numbers in vivo, and HPC proliferative responsiveness in vitro. There is a decrease in bone marrow HPC proliferation in p18(-/-) mice commensurate with decreased numbers of HPC, suggesting a positive role for p18 on HPC in vivo, similar to that for p21. These positive effects of p18 dominate negative effects of p27 gene deletion. Moreover, the CDKIs differentially regulate responsiveness of granulocyte macrophage (GM) progenitors to synergistic cell proliferation in response to GM-CSF plus SCF, which is considered important for normal hematopoiesis. Responsiveness of HPCs to inhibition by myelosuppressive chemokines is directly related to the capacity of HPCs to respond to synergistic stimulation, and their cell cycle status. P18(INK4c) gene deletion rescued the loss of chemokine suppression of synergistic proliferation due to deletion of p21(CIP1/WAF1). These findings underscore the complex interplay of cell cycle regulators in HPC, and demonstrate that loss of one can sometimes be compensated by loss of another CDKI in both, a pro- or anti-proliferative context.
• DEK Regulates Hematopoietic Stem Engraftment and Progenitor Cell Proliferation Stem Cells and Development. Jun, 2012  |   Pubmed ID: 21943234 DEK is a biochemically distinct protein that is generally found in the nucleus, where it is vital to global heterochromatin integrity. However, DEK is also secreted by cells (eg, macrophages) and influences other adjacent cells (eg, acts as a chemoattractant for certain mature blood cells). We hypothesized that DEK may modulate functions of hematopoietic stem (HSCs) and progenitor (HPCs) cells. C57Bl/6 mice were used to demonstrate that absolute numbers and cycling status of HPCs (colony forming unit-granulocyte macrophage [CFU-GM], burst forming unit-erythroid [BFU-E], and colony forming unit-granulocyte erythroid macrophage megakaryocyte [CFU-GEMM]) in bone marrow (BM) and spleen were significantly enhanced in DEK -/- as compared with wild-type (WT) control mice. Moreover, purified recombinant DEK protein inhibited colony formation in vitro by CFU-GM, BFU-E, and CFU-GEMM from WT BM cells and human cord blood (CB) cells in a dose-dependent fashion, demonstrating that DEK plays a negative role in HPC proliferation in vitro and in vivo. Suppression was direct acting as determined by inhibition of proliferation of single isolated CD34(+) CB cells in vitro. In contrast, DEK -/- BM cells significantly demonstrated reduced long term competitive and secondary mouse repopulating HSC capacity compared with WT BM cells, demonstrating that DEK positively regulates engrafting capability of self-renewing HSCs. This demonstrates that DEK has potent effects on HSCs, HPCs, and hematopoiesis, information of biological and potential clinical interest.
• Angiopoietin-like-2 and -3 Act Through Their Coiled-coil Domains to Enhance Survival and Replating Capacity of Human Cord Blood Hematopoietic Progenitors Blood Cells, Molecules & Diseases. Jan, 2012  |   Pubmed ID: 21983347 Several angiopoietin-like (ANGPTL) molecules have been implicated in enhancement of ex-vivo expansion of murine and human (hu) hematopoietic stem cells, but there are no reports on hematopoietic progenitor cells (HPCs). We assessed purified recombinant endotoxin-free hu ANGPTL-2 Coiled-Coil (CC), -3, -3CC, -3 fibrinogen-like domain (FLD), -4, -4CC, -5CC, -6 and -7 for effects on proliferation and survival of HPCs from hu cord blood (CB). None of the ANGPTL molecules stimulated CB HPC proliferation, or enhanced or inhibited colony formation of CB HPC stimulated by various growth factors. However, ANGPTL-2CC, -3, and -3CC significantly enhanced survival of HPC (CFU-GM, BFU-E, CFU-GEMM) subjected to delayed addition of growth factors. Survival enhancing effects of ANGPTL-3 were neutralized by purified anti-ANGPTL-3, but not by anti-ANGPTL-4, -6, or -7. ANGPTL-2CC, -3, and -3CC, but not -4, -6, or -7 also enhanced replating capacity of single CB CFU-GEMM colonies, an estimate of the self-renewal capabilities of HPCs, by greater than 2 fold. Effects of at least ANGPTL-3CC may in part be mediated through phosphorylation of ERK. The ANGPTL molecules did not influence ex-vivo expansion of hu CB CD34(+) cells, alone, or in combination with SCF, TPO, Flt3-ligand, with or without IL-3. Thus, among ANGPTL family members, ANGPTL-2 and -3 had enhancing activities on human HPC survival and replating activity, effects requiring the CC domain of the ANGPTL molecules. This information is of relevance to hu HPC regulation.
• The Hibernating 13-lined Ground Squirrel As a Model Organism for Potential Cold Storage of Platelets American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. May, 2012  |   Pubmed ID: 22492817 Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.
• CD1d Expression on and Regulation of Murine Hematopoietic Stem and Progenitor Cells Blood. Jun, 2012  |   Pubmed ID: 22535665 In the present study, surface CD1d, which is involved in immune cell interactions, was assessed for effects on hematopoiesis. Mouse BM hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) express CD1d. The numbers and cycling status of HPCs in the BM and spleen of different strains of cd1d(-/-) mice were enhanced significantly, suggesting that CD1d is a negative regulator of HPCs. In support of this, CD1d was required for the SCF and Flt3 ligand synergistic enhancement of CSF induction of HPC colony formation and for HPC response to myelosuppressive chemokines. Colony formation by immature subsets of HPCs was greatly enhanced when normal, but not cd1d(-/-), BM cells were pretreated with CD1d Abs in vitro. These effects required the full CD1d cytoplasmic tail. In contrast, long-term, but not short-term, repopulating HSC engraftment was impaired significantly, an effect that was minimally influenced by the presence of a truncated CD1d cytoplasmic tail. Pretreatment of normal BM cells with CD1d Abs greatly enhanced their engraftment of HSCs. The results of the present study implicate CD1d in a previously unrecognized regulatory role of normal and stressed hematopoiesis.
• Immunomodulatory Effect of the Topical Ophthalmic Janus Kinase Inhibitor Tofacitinib (CP-690,550) in Patients with Dry Eye Disease Ophthalmology. Jul, 2012  |   Pubmed ID: 22607938 To evaluate the immunomodulatory effect of topical ophthalmic tofacitinib (CP-690,550) after an 8-week treatment period in patients with dry eye disease (DED).
• Mouse Hematopoietic Cell-targeted STAT3 Deletion: Stem/progenitor Cell Defects, Mitochondrial Dysfunction, ROS Overproduction, and a Rapid Aging-like Phenotype Blood. Sep, 2012  |   Pubmed ID: 22665934 Nuclear transcription factor Stat3 is important for proper regulation of hematopoietic stem cell (HSC) and hematopoietic progenitor cell (HPC) proliferation, survival, and cytokine signaling responses. A new, noncanonical role for Stat3 in mitochondrial function has been discovered recently. However, there is little information on the role(s) of mitochondrial Stat3 in HSC/HPC function, especially potential effects of Stat3/mitochondrial dysregulation in human diseases. We investigated hematopoietic cell-targeted deletion of the STAT3 gene in HSCs/HPCs with a focus on mitochondrial function. We found that STAT3(-/-) mice, which have a very shortened lifespan, dysfunctional/dysregulated mitochondrial function and excessive reactive oxygen species production in HSCs/HPCs that coincides with pronounced defects in function. These animals have a blood phenotype with similarities to premature aging and to human diseases of myelodysplastic syndrome and myeloproliferative neoplasms such as erythroid dysplasia, anemia, excessive myeloproliferation, and lymphomyeloid ratio shifts. We show herein that the lifespan of STAT3(-/-) animals is lengthened by treatment with a reactive oxygen species scavenger, which lessened the severity of the blood phenotype. These data suggest a need for more detailed studies of role(s) of Stat3 in HSC/HPC mitochondrial function in human diseases and raise the idea that mitochondrial Stat3 could be used as a potential therapeutic target.
• Stereoscopic Viewing and Reported Perceived Immersion and Symptoms Optometry and Vision Science : Official Publication of the American Academy of Optometry. Jul, 2012  |   Pubmed ID: 22733100 Stereoscopic 3D displays heighten perceived immersion but elevate viewing symptoms for some viewers. The present study measured prevalence and magnitude of perceived immersion and viewing symptoms in stereoscopic viewing, and related them to viewer's characteristics and viewing position.
• Deep Brain Stimulation for Movement Disorders: Patient Selection and Technical Options Cleveland Clinic Journal of Medicine. Jul, 2012  |   Pubmed ID: 22761265 Deep brain stimulation (DBS) is used as a treatment for movement disorders. Unlike ablative procedures, DBS is reversible and adjustable. It is approved in the United States for treatment of Parkinson disease (PD), dystonia, and tremor. This surgical procedure is considered safe and effective for the management of the motor symptoms of these disorders, although it does not cure the underlying conditions. Potential complications of DBS surgery include intracranial hemorrhage, infections, and complications related to the hardware. There may also be complications related to stimulation or programming, although these are usually associated with dosages of dopaminergic medications and are reversible. DBS is usually performed under conscious sedation with awake evaluation during intraoperative physiologic testing. Typically, the procedure is performed with stereotactic image guidance, using computed tomography or magnetic resonance imaging (MRI) for targeting. Surgery can be accomplished with stereotactic frames or frameless systems. Recently, intraoperative MRI guidance has become available and is an alternative to the traditional surgical procedure, allowing for implantation of the DBS device under general anesthesia.
• Surgical Considerations for Tremor and Dystonia Cleveland Clinic Journal of Medicine. Jul, 2012  |   Pubmed ID: 22761270 Deep brain stimulation (DBS) is among the most effective approaches for the treatment of patients with advanced movement disorders. In patients with essential tremor, stimulation typically targets the ventral intermediate nucleus of the thalamus. Results of several studies have shown that over a follow-up period of 1 to 5 years, the severity of tremor decreases by an average of approximately 50% from baseline. Ongoing research continues to define the optimal stimulation parameters for patients with tremor, including frequency, voltage, and pulse width. In patients with dystonia, DBS typically targets the globus pallidus internus or the subthalamic nucleus. Long-term prospective clinical trials demonstrated reductions in motor severity rating scale scores of approximately 50% to 80% over follow-up periods of 2 to 3 years. Serious adverse events were uncommon, and included lead failures and infections. Appropriate candidates for DBS treatment of dystonia include patients with an unequivocal diagnosis of dystonia and significant disability. Several issues in the use of DBS for movement disorders remain unresolved, including the intensity of appropriate medical management before undergoing DBS, the importance of intraoperative mapping, optimal stimulator programming, and the time course of the beneficial effects of treatment.
• Long-term Effects of Deep Brain Stimulation for Essential Tremor with Subjective and Objective Quantification Via Mailed-in Questionnaires Stereotactic and Functional Neurosurgery. 2012  |   Pubmed ID: 23018417 Deep brain stimulation (DBS) is a standard treatment for patients with disabling essential tremor. The short-term efficacy rate is well established.
• Dipeptidylpeptidase 4 Negatively Regulates Colony-stimulating Factor Activity and Stress Hematopoiesis Nature Medicine. Dec, 2012  |   Pubmed ID: 23160239 Enhancement of hematopoietic recovery after radiation, chemotherapy, or hematopoietic stem cell (HSC) transplantation is clinically relevant. Dipeptidylpeptidase (DPP4) cleaves a wide variety of substrates, including the chemokine stromal cell-derived factor-1 (SDF-1). In the course of experiments showing that inhibition of DPP4 enhances SDF-1-mediated progenitor cell survival, ex vivo cytokine expansion and replating frequency, we unexpectedly found that DPP4 has a more general role in regulating colony-stimulating factor (CSF) activity. DPP4 cleaved within the N-termini of the CSFs granulocyte-macrophage (GM)-CSF, G-CSF, interleukin-3 (IL-3) and erythropoietin and decreased their activity. Dpp4 knockout or DPP4 inhibition enhanced CSF activities both in vitro and in vivo. The reduced activity of DPP4-truncated versus full-length human GM-CSF was mechanistically linked to effects on receptor-binding affinity, induction of GM-CSF receptor oligomerization and signaling capacity. Hematopoiesis in mice after radiation or chemotherapy was enhanced in Dpp4(-/-) mice or mice receiving an orally active DPP4 inhibitor. DPP4 inhibition enhanced engraftment in mice without compromising HSC function, suggesting the potential clinical utility of this approach.
• Complex Impacts of an Invasive Omnivore and Native Consumers on Stream Communities in California and Hawaii Oecologia. Apr, 2013  |   Pubmed ID: 22983299 The effects of invasive species on native communities often depend on the characteristics of the recipient community and on the food habits of the invasive species, becoming complicated when the invader is omnivorous. In field enclosure experiments, we assessed the direct and interactive effects of an invasive omnivorous crayfish (Procambarus clarkii) and either native herbivorous snails (Physella gyrina) or shrimp (Atyoida bisulcata) on stream communities in California and Hawaii, respectively. Based on literature data and the characteristics of each study site, we predicted that crayfish would affect primarily algal-based trophic linkages in an open California stream but detritus-based trophic linkages in a shaded Hawaiian stream, with trophic cascades mediated through crayfish effects on primary consumers being observed in both systems. As predicted, crayfish in California directly reduced periphyton, filamentous algae, sediment, and snail levels, but generated a cascade by decreasing snail densities and increasing periphyton biomass. Contrary to prediction, crayfish did not reduce total invertebrate biomass. As predicted, crayfish in Hawaii reduced leaf litter, filamentous algae, and benthic invertebrate biomass. Contrary to our predictions, however, a trophic cascade was not observed because shrimp did not affect periphyton levels, crayfish did not reduce shrimp abundance, and crayfish had greater negative impacts on filamentous algae than did shrimp. Our findings highlight that the same invasive species can generate different effects on disparate systems, probably as mediated through the availability of different food types, flexibility in the invasive species' food habits, and complex pathways of trophic interaction.
• Association of Deep Brain Stimulation Washout Effects with Parkinson Disease Duration JAMA Neurology. Jan, 2013  |   Pubmed ID: 23070397 Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves symptoms of Parkinson disease (PD), including bradykinesia. When stimulation ceases abruptly, bradykinesia returns gradually. The duration of the gradual, slow washout varies across patients, and although the origin of this variability is unclear, it is hypothesized to be related to 1 or more clinical characteristics of patients.
• Hematopoietic Colony Formation from Human Growth Factor-dependent TF1 Cells and Human Cord Blood Myeloid Progenitor Cells Depends on SHP2 Phosphatase Function Stem Cells and Development. Mar, 2013  |   Pubmed ID: 23082805 The protein tyrosine phosphatase, SHP2, is widely expressed; however, previous studies demonstrated that hematopoietic cell development more stringently requires Shp2 expression compared to other tissues. Furthermore, somatic gain-of-function SHP2 mutants are commonly found in human myeloid leukemias. Given that pharmacologic inhibitors to SHP2 phosphatase activity are currently in development as putative antileukemic agents, we conducted a series of experiments examining the necessity of SHP2 phosphatase activity for human hematopoiesis. Anti-sense oligonucleotides to human SHP2 coding sequences reduced human cord blood- and human cell line, TF1-derived colony formation. Expression of truncated SHP2 bearing its Src homology 2 (SH2) domains, but lacking the phosphatase domain similarly reduced human cord blood- and TF1-derived colony formation. Mechanistically, expression of truncated SHP2 reduced the interaction between endogenous, full-length SHP2 with the adapter protein, Grb2. To verify the role of SHP2 phosphatase function in human hematopoietic cell development, human cord blood CD34+ cells were transduced with a leukemia-associated phosphatase gain-of-function SHP2 mutant or with a phosphatase dead SHP2 mutant, which indicated that increased phosphatase function enhanced, while decreased SHP2 phosphatase function reduced, human cord blood-derived colonies. Collectively, these findings indicate that SHP2 phosphatase function regulates human hematopoietic cell development and imply that the phosphatase component of SHP2 may serve as a pharmacologic target in human leukemias bearing increased SHP2 phosphatase activity.
• Independent and Combined Effects of Acute Physiological Hyperglycaemia and Hyperinsulinaemia on Metabolic Gene Expression in Human Skeletal Muscle Clinical Science (London, England : 1979). Jun, 2013  |   Pubmed ID: 23316693 Physiological hyperglycaemia and hyperinsulinaemia are strong modulators of gene expression, which underpins some of their well-known effects on insulin action and energy metabolism. The aim of the present study was to examine whether acute in vivo exposure of healthy humans to hyperinsulinaemia and hyperglycaemia have independent or additive effects on expression of key metabolic genes in skeletal muscle. On three randomized occasions, seven young subjects underwent a 4 h (i) hyperinsulinaemic (50 m-units·m⁻²·min⁻¹) hyperglycaemic (10 mmol/l) clamp (HIHG), (ii) hyperglycaemic (10 mmol/l) euinsulinaemic (5 m-units·m⁻²·min⁻¹) clamp (LIHG) and (iii) hyperinsulinaemic (50 m-units·m⁻²·min⁻¹) euglycaemic (4.5 mmol/l) clamp (HING). Muscle biopsies were obtained before and after each clamp for the determination of expression of genes involved in energy metabolism, and phosphorylation of key insulin signalling proteins. Hyperinsulinaemia and hyperglycaemia exerted independent effects with similar direction of modulation on PI3KR1 (phosphatidylinositol 3-kinase, regulatory 1), LXRα (liver X receptor α), PDK4 (pyruvate dehydrogenase kinase 4) and FOXO1 (forkhead box O1A) and produced an additive effect on PI3KR1, the gene that encodes the p85α subunit of PI3K in human skeletal muscle. Acute hyperglycaemia itself altered the expression of genes involved in fatty acid transport and oxidation [fatty acid transporter (CD36), LCAD (long-chain acyl-CoA dehydrogenase) and FOXO1], and lipogenesis [LXRα, ChREBP (carbohydrate-responseelement-binding protein), ABCA1 (ATP-binding cassette transporter A1) and G6PD (glucose-6-phosphate dehydrogenase). Surperimposing hyperinsulinaemia on hyperglycaemia modulated a number of genes involved in insulin signalling, glucose metabolism and intracellular lipid accumulation and exerted an additive effect on PI3KR1. These may be early molecular events that precede the development of glucolipotoxicity and insulin resistance normally associated with more prolonged periods of hyperglycaemia and hyperinsulinaemia.
• Successful Deep Brain Stimulation Surgery with Intraoperative Magnetic Resonance Imaging on a Difficult Neuroacanthocytosis Case: Case Report Neurosurgery. Jul, 2013  |   Pubmed ID: 23615095 Chorea acanthocytosis is a progressive hereditary neurodegenerative disorder characterized by hyperkinetic movements, seizures, and acanthocytosis in the absence of any lipid abnormality. Medical treatment is typically limited and disappointing.
• A Role for DEK in Stem/Progenitor Cell Biology Stem Cells (Dayton, Ohio). Jun, 2013  |   Pubmed ID: 23733396 Understanding the factors that regulate hematopoiesis opens up the possibility of modifying these factors and their actions for clinical benefit. DEK, a non-histone nuclear phosphoprotein initially identified as a putative proto-oncogene, has recently been linked to regulation of hematopoiesis. DEK has myelosuppressive activity in vitro on proliferation of human and mouse hematopoietic progenitor cells and enhancing activity on engraftment of long term marrow repopulating mouse stem cells, has been linked in coordinate regulation with the transcription factor C/EBPα, for differentiation of myeloid cells, and apparently targets a long term repopulating hematopoietic stem cell for leukemic transformation. This review covers the uniqueness of DEK, what is known about how it now functions as a nuclear protein and also as a secreted molecule that can act in paracrine fashion, and how it may be regulated in part by Dipeptidylpeptidase 4, an enzyme known to truncate and modify a number of proteins involved in activities on hematopoietic cells. Examples are provided of possible future areas of investigation needed to better understand how DEK may be regulated and function as a regulator of hematopoiesis, information possibly translatable to other normal and diseased immature cell systems.