44 research outputs found

    Coherent states for exactly solvable potentials

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    A general algebraic procedure for constructing coherent states of a wide class of exactly solvable potentials e.g., Morse and P{\"o}schl-Teller, is given. The method, {\it a priori}, is potential independent and connects with earlier developed ones, including the oscillator based approaches for coherent states and their generalizations. This approach can be straightforwardly extended to construct more general coherent states for the quantum mechanical potential problems, like the nonlinear coherent states for the oscillators. The time evolution properties of some of these coherent states, show revival and fractional revival, as manifested in the autocorrelation functions, as well as, in the quantum carpet structures.Comment: 11 pages, 4 eps figures, uses graphicx packag

    Essential versus accessory aspects of cell death: recommendations of the NCCD 2015

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    Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as ‘accidental cell death’ (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. ‘Regulated cell death’ (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death

    Zebrafish as a Model System to Study the Physiological Function of Telomeric Protein TPP1

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    Telomeres are specialized chromatin structures at the end of chromosomes. Telomere dysfunction can lead to chromosomal abnormalities, DNA damage responses, and even cancer. In mammalian cells, a six-protein complex (telosome/shelterin) is assembled on the telomeres through the interactions between various domain structures of the six telomere proteins (POT1, TPP1, TIN2, TRF1, TRF2 and RAP1), and functions in telomere maintenance and protection. Within the telosome, TPP1 interacts directly with POT1 and TIN2 and help to mediate telosome assembly. Mechanisms of telomere regulation have been extensively studied in a variety of model organisms. For example, the physiological roles of telomere-targeted proteins have been assessed in mice through homozygous inactivation. In these cases, early embryonic lethality has prevented further studies of these proteins in embryogenesis and development. As a model system, zebrafish offers unique advantages such as genetic similarities with human, rapid developmental cycles, and ease of manipulation of its embryos. In this report, we detailed the identification of zebrafish homologues of TPP1, POT1, and TIN2, and showed that the domain structures and interactions of these telosome components appeared intact in zebrafish. Importantly, knocking down TPP1 led to multiple abnormalities in zebrafish embryogenesis, including neural death, heart malformation, and caudal defect. And these embryos displayed extensive apoptosis. These results underline the importance of TPP1 in zebrafish embryogenesis, and highlight the feasibility and advantages of investigating the signaling pathways and physiological function of telomere proteins in zebrafish

    Response patterns of hairy cell leukemia to B-cell mitogens and growth factors

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    The effect of mitogens and/or recombinant B-cell growth factors (M/GFs) on the in vitro growth of hairy cells was examined. Tumor cells were isolated from the spleens of four patients with hairy cell leukemia (HCL) by Ficoll-Hypaque sedimentation and E-rosetting. Enrichment for tumor cells was confirmed with intracytoplasmic immunoglobulin (Ig) staining, tartrate resistant acid phosphatase (TRAP) staining, and staining using monoclonal antibodies (MoAbs) directed at B, T, myeloid, and monocytoid antigens (Ags) in indirect immunofluorescence assays. Tumor cells were B1(CD20)+ B2(CD21)- B4(CD19)+ IL-2R(CD25)+ PCA-1 +/- TRAP+. HCLs neither synthesized DNA nor secreted Ig in response to culture with granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-3, IL-4, IL-5, or IL-6. However, a proliferative response (stimulation index greater than or equal to 3.0) without Ig secretion was triggered in HCLs by mitogens or combinations of GFs. Specifically, DNA synthesis was induced at 3 days in three of four HCL samples cultured with Staphylococcus aureus Cowan A (SAC) or the combination of phorbol ester (TPA) and the calcium ionophore A 23187 (Ca2+); DNA synthesis was triggered later (day 7) by tumor necrosis factor (TNF) or by IL-4 and IL-5. In contrast, the fourth patient, a nonresponder to SAC or TPA/Ca2+, demonstrated increased DNA synthesis at day 3 when cocultured with IL-4 and IL-5. Both autoradiography and staining with antibromodeoxyuridine (BrdU) MoAb conjugated to fluorescein confirmed DNA synthesis by only a minority (5% to 23%) of tumor cells within each patient. Dual staining confirmed that responsive cells were both BrdU+ and TRAP+. DNA synthesis induced by TPA/Ca2+ was blocked specifically by anti-IL-6 Ab; in contrast, the HCL proliferative response to SAC, TNF, or IL-4 and IL- 5 was not inhibited by anti-IL-6 Ab. alpha-Interferon inhibited the response to TPA/Ca2+, TNF, or IL-4 and IL-5 without any effect on response to SAC. Finally, peroxidase-antiperoxidase staining demonstrated that HCLs are induced by TPA/Ca2+, but not by SAC, to produce intracytoplasmic IL-6. These data demonstrate IL-4, IL-5, and IL-6 mediated DNA synthesis by HCLs in vitro and suggest a possible in vivo role for these growth factors in the pathophysiology of HCL.</jats:p

    Response patterns of hairy cell leukemia to B-cell mitogens and growth factors

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    Abstract The effect of mitogens and/or recombinant B-cell growth factors (M/GFs) on the in vitro growth of hairy cells was examined. Tumor cells were isolated from the spleens of four patients with hairy cell leukemia (HCL) by Ficoll-Hypaque sedimentation and E-rosetting. Enrichment for tumor cells was confirmed with intracytoplasmic immunoglobulin (Ig) staining, tartrate resistant acid phosphatase (TRAP) staining, and staining using monoclonal antibodies (MoAbs) directed at B, T, myeloid, and monocytoid antigens (Ags) in indirect immunofluorescence assays. Tumor cells were B1(CD20)+ B2(CD21)- B4(CD19)+ IL-2R(CD25)+ PCA-1 +/- TRAP+. HCLs neither synthesized DNA nor secreted Ig in response to culture with granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-3, IL-4, IL-5, or IL-6. However, a proliferative response (stimulation index greater than or equal to 3.0) without Ig secretion was triggered in HCLs by mitogens or combinations of GFs. Specifically, DNA synthesis was induced at 3 days in three of four HCL samples cultured with Staphylococcus aureus Cowan A (SAC) or the combination of phorbol ester (TPA) and the calcium ionophore A 23187 (Ca2+); DNA synthesis was triggered later (day 7) by tumor necrosis factor (TNF) or by IL-4 and IL-5. In contrast, the fourth patient, a nonresponder to SAC or TPA/Ca2+, demonstrated increased DNA synthesis at day 3 when cocultured with IL-4 and IL-5. Both autoradiography and staining with antibromodeoxyuridine (BrdU) MoAb conjugated to fluorescein confirmed DNA synthesis by only a minority (5% to 23%) of tumor cells within each patient. Dual staining confirmed that responsive cells were both BrdU+ and TRAP+. DNA synthesis induced by TPA/Ca2+ was blocked specifically by anti-IL-6 Ab; in contrast, the HCL proliferative response to SAC, TNF, or IL-4 and IL- 5 was not inhibited by anti-IL-6 Ab. alpha-Interferon inhibited the response to TPA/Ca2+, TNF, or IL-4 and IL-5 without any effect on response to SAC. Finally, peroxidase-antiperoxidase staining demonstrated that HCLs are induced by TPA/Ca2+, but not by SAC, to produce intracytoplasmic IL-6. These data demonstrate IL-4, IL-5, and IL-6 mediated DNA synthesis by HCLs in vitro and suggest a possible in vivo role for these growth factors in the pathophysiology of HCL.</jats:p

    Response patterns of purified myeloma cells to hematopoietic growth factors

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    Abstract Tumor cells were isolated from the bone marrow of seven patients with multiple myeloma and from the peripheral blood of three patients with plasma cell leukemia using Ficoll-Hypaque (FH) density sedimentation followed by immune rosette depletion of T, myeloid, monocytoid, and natural killer (NK) cells. Enrichment to greater than or equal to 93% plasma cells was confirmed with Wright's-Giemsa staining, with intracytoplasmic immunoglobulin staining, and with staining using monoclonal antibodies (MoAbs) directed at B, T, myeloid, monocytoid, and myeloma antigens in indirect immunofluorescence assays. Myeloma cells neither proliferated nor secreted Ig in response to G/M-CSF, G- CSF, M-CSF, interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), or interleukin-4 (IL-4). Significant proliferation (SI greater than or equal to 3.0) was induced by interleukin-6 (IL-6) in six of ten patients (SI of 31 and 43 in two cases); and to interleukin-3 (IL-3) and interleukin-5 (IL-5), independently, in two patients each. Peak proliferation to IL-5 or IL-6 and to IL-3 occurred in cells pulsed with 3[H] thymidine at 24 and 48 hours, respectively; and proliferation to combinations of factors did not exceed that noted to IL-6 alone; Ig secretion was not documented under any culture conditions. Three myeloma-derived cell lines similarly studied demonstrated variable responses. The heterogeneity in the in vitro responses of myeloma cells and derived cell lines to exogenous growth factors enhances our understanding of abnormal plasma cell growth and may yield insight into the pathophysiology of plasma cell dyscrasias.</jats:p

    Adhesion of human myeloma-derived cell lines to bone marrow stromal cells stimulates interleukin-6 secretion

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    Previous studies show that human myeloma-derived cell lines specifically adhere to fibronectin (FN) through very late antigen-4 (VLA-4; alpha 4 beta 1 integrin complex) and RGD-peptide mechanisms, which may contribute to the localization of tumor cells in bone marrow (BM). In these studies, we characterized the adhesion of myeloma- derived cell lines to both normal and myeloma BM stromal cells (BMSCs) and the effect of adhesion on DNA synthesis. Because interleukin-6 (IL- 6) plays an important role in the pathogenesis of multiple myeloma, we also examined the effects of tumor cell adhesion on IL-6 secretion by BMSCs. In 51chromium binding assays, the U266, ARH-77, and IM-9 cell lines showed 52% +/- 12%, 55% +/- 6%, and 47% +/- 7% specific adherence, respectively, to normal BMSCs and 74% +/- 4%, 60% +/- 3%, and 61% +/- 6% specific adherence, respectively, to myeloma BMSCs. In contrast, only 12% to 13% specific binding of HS-Sultan cells to BMSCs was noted. The binding of myeloma cells to BMSCs was partially blocked with anti-beta 1 monoclonal antibody (MoAb), anti-beta 2 integrin MoAb, and excess RGD peptide, suggesting multiple mechanisms for the adhesion of myeloma cell lines to BMSCs. Binding of cell lines to FN or myeloma BMSCs did not affect cell line proliferation; however, adhesion of myeloma cell lines to normal BMSCs decreased DNA synthesis, ie, stimulation indices are 0.1 +/- 0.04, 0.2 +/- 0.1, 0.2 +/- 0.07, and 0.1 +/- 0.06 for the adherent non-IL-6-dependent U266, ARH-77, HS- Sultan, and IM-9 cells, respectively (n = 5, P &lt; .01). In contrast, adherence of IL-6-dependent B9 cells increased their proliferation (stimulation index, 3.2 +/- 0.7). Significant (twofold to eightfold) increases in IL-6 secretion were evident in cell line-adherent (&gt; or = 12 hours) normal and myeloma BMSC cultures. Paraformaldehyde fixation of BMSCs before adhesion completely abrogated IL-6 secretion, suggesting that IL-6 secretion was triggered in BMSCs rather than in cell lines. Partial blocking of cell line adhesion to BMSCs, using anti- beta 1 integrin and anti-beta 2 integrin MoAbs and RGD peptide, also partially blocked the triggering of IL-6 secretion by BMSCs. When cell lines were placed in Transwell inserts and then cultured with either normal or myeloma BMSCs, permitting juxtaposition without cell to cell contact between myeloma cell lines and BMSCs, no increase in IL-6 secretion was observed.(ABSTRACT TRUNCATED AT 400 WORDS)</jats:p

    Characterization of adhesion molecules on human myeloma cell lines

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    Abstract In multiple myeloma, malignant plasma cells are localized in marrow and rarely circulate in peripheral blood. To investigate the role of adhesion proteins in this process, we determined the expression and function of adhesion molecules on cell lines derived from patients with myeloma. The U266, ARH-77, IM-9, and HS-Sultan cell lines strongly expressed beta 1 and alpha 4 integrins (89% to 98% positive), confirming that VLA-4 is the principal integrin on these cell lines. The U266 and IM-9 cell lines also expressed alpha 3 integrin on 15% to 20% cells. In contrast, all lines lacked cell surface alpha 2, alpha 5, and alpha 6 integrin expression (&lt; 5% positive). These cell lines adhered to fibronectin (20% to 40% specific binding), without significant binding to either collagen or laminin. Adhesion of these cell lines to fibronectin was partially blocked with either anti-beta 1 integrin monoclonal antibody (MoAb) (75% inhibition), anti-alpha 4 integrin MoAb (75% inhibition), or RGD peptide (50% inhibition), but was unaffected by anti-alpha v beta 3 or anti-alpha IIb beta 3 MoAbs. Moreover, the combination of anti-beta 1 plus RGD peptide or anti-alpha 4 plus RGD peptide inhibited binding to fibronectin by 80% and 95%, respectively. Finally, pretreatment and coculture of the IM-9 cell line with interleukin-6 (IL-6) resulted in a 52% decrease in specific binding to fibronectin (30% +/- 6% to 15% +/- 6%; P = .001), associated with a decrease in the number of cells expressing VLA-4 and a decrease in intensity of VLA-4 expression. These data suggest that myeloma cells adhere to fibronectin through VLA-4 as well as through RGD-dependent mechanisms, and that this binding can be downregulated by IL-6. Future studies of binding of both myeloma cell lines and freshly isolated tumor cells to extracellular matrix proteins and to marrow stroma may enhance our understanding of localization and trafficking of cells within the bone marrow microenvironment.</jats:p
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