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LEUKEMIA INHIBITORY FACTOR (CHOLINERGIC DIFFERENTIATION FACTOR)[HOMO SAPIENS].
LATEST LITERATURE
1: BMC musculoskeletal disorders, 2010 Sep 6, 11(1)
The European multicenter trial on the safety and efficacy of guided oblique lumbar interbody fusion (GO-LIF).
[Abstract]ABSTRACT: BACKGROUND: Because of the implant-related problems with pedicle screw-based spinal instrumentations, other types of fixation have been tried in spinal arthrodesis. One such technique is the direct trans-pedicular, trans-discal screw fixation, pioneered by Grob for spondylolisthesis. The newly developed GO-LIF procedure expands the scope of the Grob technique in several important ways and adds security by means of robotic-assisted navigation. This is the first clinical trial on the GO-LIF procedure and it will assess safety and efficacy. Methods / Design: Multicentric prospective study with n=40 patients to undergo single level instrumented spinal arthrodesis of the lumbar or the lumbosacral spine, based on a diagnosis of: painful disc degeneration, painful erosive osteochondrosis, segmental instability, recurrent disc herniation, spinal canal stenosis or foraminal stenosis. The primary target criteria with regards to safety are: The number, severity and cause of intra- and perioperative complications. The number of significant penetrations of the cortical layer of the vertebral body by the implant as recognized on postoperative CT. The primary target parameters with regards to feasibility are: Performance of the procedure according to the preoperative plan. The planned follow-up is 12 months and the following scores will be evaluated as secondary target parameters with regards to clinical improvement: VAS back pain, VAS leg pain, Oswestry Disability Index, short form - 12 health questionnaire and the Swiss spinal stenosis questionnaire for patients with spinal claudication. The secondary parameters with regards to construct stability are visible fusion or lack thereof and signs of implant loosening, implant migration or pseudarthrosis on plain and functional radiographs. DISCUSSION: This trial will for the first time assess the safety and efficacy of guided oblique lumbar interbody fusion. There is no control group, but the results, the outcome and the rate of any complications will be analyzed on the background of the literature on instrumented spinal fusion. Despite its limitations, we expect that this study will serve as the key step in deciding whether a direct comparative trial with another fusion technique is warranted. Trial Registration: Clinical Trials NCT00810433.
2: The Journal of chemical physics, 2010 Jul 14, 133(2)
Ab initio energy landscape of LiF clusters.
[Abstract]A global search for possible LiF cluster structures is performed up to (LiF)(8). The method is based on simulated annealing, where all the energies are evaluated on the ab initio level. In addition, the threshold algorithm is employed to determine the energy barriers for the transitions among these structures, for the cluster (LiF)(4), again on the ab initio level, and the corresponding tree graph is obtained.
3: The journal of physical chemistry. B, 2010 Apr 27, 58(8)
In Situ Experimental Evidence for a Nonmonotonous Structural Evolution with Composition in the Molten LiF-ZrF(4) System.
[Abstract]We propose in this paper an original approach to study the structure of the molten LiF-ZrF(4) system up to 50 mol % ZrF(4), combining high-temperature nuclear magnetic resonance (NMR) and extended X-ray absorption fine structure (EXAFS) experiments with molecular dynamics (MD) calculations. (91)Zr high-temperature NMR experiments give an average coordination of 7 for the zirconium ion on all domains of composition. MD simulations, in agreement with EXAFS experiments at the K-edge of Zr, provide evidence for the coexistence of three different Zr-based complexes, [ZrF(6)](2-), [ZrF(7)](3-), and [ZrF(8)](4-), in the melt; the evolution of the concentration of these species upon addition of ZrF(4) is quantified. Smooth variations are observed, apart from a given composition at 35 mol % ZrF(4), for which an anomalous point is observed. Concerning the anion coordination, we observe a predominance of free fluorides at low concentrations in ZrF(4), and an increase of the number of bridging fluoride ions between complexes with addition of ZrF(4).
4: Lasers in medical science, 2010 Apr 15, 68(6)
Characterization of dental caries by LIF spectroscopy with 404-nm excitation.
[Abstract]The potential of laser-induced fluorescence (LIF) spectroscopy for the characterization of different stages of dental caries using 404-nm diode laser excitation was investigated. In vitro spectra from 16 sound, 10 noncavitated carious and 10 cavitated carious molar teeth were recorded on a miniature fibre-optic spectrometer. The areas under the receiver operating characteristics (ROC-AUC) were calculated and one-way analysis of variance (ANOVA) was performed. The LIF spectra of the carious teeth showed two peaks at 635 and 680 nm in addition to a broad band seen at 500 nm in sound teeth. The fluorescence intensity ratios, F500/F635 and F500/F680, in carious teeth were always lower than those in sound teeth. The ROC-AUC for discriminating between carious and sound teeth was 0.94, and for discriminating between noncavitated and cavitated carious teeth was 0.87. Statistically significant differences (p<0.001) were seen between sound, noncavitated carious and cavitated carious teeth. The results showed that LIF spectroscopy has the potential to be useful for characterizing different stages of caries in a clinical setting.
5: Electrophoresis, 2010 Mar 22, 35(1)
Improved sample preparation method for glycan analysis of glycoproteins by CE-LIF and CE-MS.
[Abstract]CE is a high-resolution separation technique broadly used in the biotechnology industry for carbohydrate analysis. The standard sample preparation protocol for CE analysis of glycans released from glycoproteins generally requires derivatization times of overnight at 37 degrees C, using >/=100 fold excess of fluorophore reagent, 8-aminopyrene-1,3,6-trisulfonic-acid, if the sample is unknown, or it is a regulated biotherapeutic product, possibly containing terminal sialic acid(s). In this paper, we report on significant improvements for the standard CE sample preparation method of glycan analysis. By replacing the conventionally used acetic acid catalyst with citric acid, as low as 1:10 glycan to fluorophore molar ratio (versus the typical 1:>/=100 ratio) maintained the >95% derivatization yield at 55 degrees C with only 50 min reaction time. Terminal sialic acid loss was negligible at 55 degrees C during the derivatization process, and indicating that the kinetics of labeling at 55 degrees C was faster than the loss of sialic acid from the glycan. The reduced relative level of 8-aminopyrene-1,3,6-trisulfonic-acid simplified the removal of excess reagent, important in both CE-LIF (electrokinetic injection bias) and CE-MS (ion suppression). Coupling CE- ESI-MS confirmed that the individual peaks separated by CE corresponded to single glycans and increased the confidence of structural assignment based on glucose unit values.
6: Stem cells and development, 2010 Sep, 19(9)
Toll-Like Receptor 2 Mediates Proliferation, Survival, NF-kappaB Translocation, and Cytokine mRNA Expression in LIF-Maintained Mouse Embryonic Stem Cells.
[Abstract]Toll-like receptor (TLR) activation is important in immune responses and in differentiation of hematopoietic stem cells. We detected mRNA expression of TLRs 1, 2, 3, 5, and 6, but not TLRs 4, 7, 8, and 9 in murine (m)ESC line E14, and noted high cell surface protein expression of TLR2, but not TLR4, for mESC lines R1, CGR8, and E14. ESC lines were cultured in the presence of leukemia inhibitory factor (LIF). Pam(3)Cys enhanced proliferation and survival of the 3 ESC lines. In contrast, lipopolysaccharide (LPS) decreased proliferation and survival. Pam(3)Cys and LPS effects on proliferation and survival were blocked by antibody to TLR2, suggesting that effects of both Pam(3)Cys and LPS on these mESC lines were likely mediated through TLR2. E14 ESC line expressed MyD88. Pam(3)Cys stimulation of E14 ESCs was associated with induced NF-kappaB translocation, enhanced phosphorylation of IKK-alpha/beta, and enhanced mRNA, but not protein, expression of tumor necrosis factor-alpha, interferon-gamma, and IL-6. TLR2 activation by Pam(3)Cys or inhibition by LPS was not associated with changes in morphology or expression of alkaline phosphatase, Oct4, SSEA1, KLF4, or Sox2, markers of undifferentiated mESCs. Our studies identify TLR2 as present and functional in E14, R1, and CGR8 mESC lines.
7: Electrophoresis, 2010 Jan 18, 31(2)
A new evaluation technique for the detection of impurities in purified proteins via CE with native UV-LIF.
[Abstract]An analytical methodology for quality control analyses of IgG and their impurities is presented using a new UV-LIF (266 nm) detector inside the cassette of a CE instrument and its performance was evaluated. The observed sensitivity was very close to that obtained by silver staining of slab gels (LOD of 25 ng/mL), while the sensitivity of the analysis is 80 times better than with CE/UV absorption (214 nm). Examples of the analysis of pharmaceutical and other commercial IgGs are provided and the kinetics of the reduction of IgG by beta-mercaptoethanol is reported, demonstrating the ease of performing the analysis.
8: Journal of colloid and interface science, 2009 Sep 20, 30(20)
Structures of D(2) layers on LiF(001).
[Abstract]Classical Monte Carlo (MC) simulations of D(2) molecules physisorbed on LiF(001) surfaces are reported and show a series of interesting commensurate structure forms, viz., p(2x2) -->p(8x2) -->p(4x2), with coverages Theta=0.5, 0.625, and 0.75, respectively, and are stable up to 8K. These structures are consistent with recent helium atom scattering (HAS) results (the p(4x2) is not observed) in terms of coverage and stability, but disagree in terms of symmetry. The p(2x2) structure contains two D(2) molecules per unit cell, with each molecule lying parallel to the plane of the surface directly above every other cationic site. For the p(4x2) structure, there are two kinds of adsorption sites: a parallel site, as in the case of p(2x2), and a tilted site, where the D(2) molecules sit between cationic and anionic sites with the molecular axis directed toward the anionic site, with a tilt angle of theta approximately 63 degrees . Perturbation theory calculations show that the adsorbed D(2) molecules are azimuthally delocalized and hence the structures are indeed c-type. Our calculations also indicate that o-D(2) and helicoptering p-D(2) species prefer cationic sites, compared to cartwheeling p-D(2) species.
9: Theriogenology, 2009 Dec 23, 113(52)
Effect of the association of IGF-I, IGF-II, bFGF, TGF-beta1, GM-CSF, and LIF on the development of bovine embryos produced in vitro.
[Abstract]This study examined the influence of the following growth factors and cytokines on early embryonic development: insulin-like growth factors I and II (IGF-I, IGF-II), basic fibroblast growth factor (bFGF), transforming growth factor (TGF-beta), granulocyte-macrophage colony-stimulating factor (GM-CSF), and leukemia inhibitory factor (LIF). Synthetic oviduct fluid (SOF) was used as the culture medium. We studied the development of bovine embryos produced in vitro and cultured until Day 9 after fertilization. TGF-beta1, bFGF, GM-CSF, and LIF used on their own significantly improved the yield of hatched blastocysts. IGF-I, bFGF, TGF-beta1, GM-CSF, and LIF significantly accelerated embryonic development, especially the change from the expanded blastocyst to hatched blastocyst stages. Use of a combination of these growth factors and cytokines (GF-CYK) in SOF medium produced higher percentages of blastocysts and hatched blastocysts than did use of SOF alone (45% and 22% vs. 24% and 12%; P<0.05) on Day 8 after in vitro fertilization and similar results to use of SOF+10% fetal calf serum (38% and 16%, at the same stages, respectively). The averages of total cells, inner cell mass cells, and trophectoderm cells of exclusively in vitro Day-8 blastocysts for pooled GF-CYK treatments were higher than those for SOF and similar to those for fetal calf serum. The presence of these growth factors and cytokines in the embryo culture medium therefore has a combined stimulatory action on embryonic development; in particular through an increase in hatching rate and in the number of cells of both the inner cell mass and trophoblast. These results are the first to demonstrate that use of a combination of recombinant growth factors and cytokine, as IGF-I, IGF-II, bFGF, TGF-beta1, LIF, and GM-CSF, produces similar results to 10% fetal calf serum for the development of in vitro-produced bovine embryos. This entirely synthetic method of embryo culture has undeniable advantages for the biosecurity of embryo transfer.
10: Cell stem cell, 2009 Dec 4, 5(6)
Oct4 and LIF/Stat3 additively induce Kr¨¹ppel factors to sustain embryonic stem cell self-renewal.
[Abstract]Embryonic stem cell (ESC) pluripotency is dependent on an intrinsic gene regulatory network centered on Oct4. Propagation of the pluripotent state is stimulated by the cytokine leukemia inhibitory factor (LIF) acting through the transcriptional regulator Stat3. Here, we show that this extrinsic stimulus converges with the intrinsic circuitry in Kr¨¹ppel-factor activation. Oct4 primarily induces Klf2 while LIF/Stat3 selectively enhances Klf4 expression. Overexpression of either factor reduces LIF dependence, but with quantitative and qualitative differences. Unlike Klf4, Klf2 increases ESC clonogenicity, maintains undifferentiated ESCs in the genetic absence of Stat3, and confers resistance to BMP-induced differentiation. ESCs expanded with Klf2 remain capable of contributing to adult chimeras. Postimplantation-embryo-derived EpiSCs lack both Klf2 and Klf4 and expression of either can reinstate naive pluripotency. These findings indicate that Oct4 and Stat3 intersect in directing expression of Klf transcriptional regulators with overlapping properties that additively reinforce ground-state ESC pluripotency, identity, and self-renewal.
11: Radiation protection dosimetry, 2009 Nov 24, 30(16)
EXPERIMENTAL INVESTIGATION OF THE 100 keV X-RAY DOSE RESPONSE OF THE HIGH-TEMPERATURE THERMOLUMINESCENCE IN LIF:MG,TI (TLD-100): THEORETICAL INTERPRETATION USING THE UNIFIED INTERACTION MODEL.
[Abstract]The dose response of LiF:Mg,Ti (TLD-100) chips was measured from 1 to 50 000 Gy using 100 keV X rays at the European Synchroton Radiation Facility. Glow curves were deconvoluted into component glow peaks using a computerised glow curve deconvolution (CGCD) code based on first-order kinetics. The normalised dose response, f(D), of glow peaks 4 and 5 and 5b (the major components of composite peak 5), as well as peaks 7 and 8 (two of the major components of the high-temperature thermoluminescence (HTTL) at high levels of dose) was separately determined and theoretically interpreted using the unified interaction model (UNIM). The UNIM is a nine-parameter model encompassing both the irradiation/absorption stage and the thermally induced relaxation/recombination stage with an admixture of both localised and delocalised recombination mechanisms. The effects of radiation damage are included in the present modelling via the exponential removal of luminescent centres (LCs) at high dose levels. The main features of the experimentally measured dose response are: (i) increase in f(D)(max) with glow peak temperature, (ii) increase in D(max) (the dose level at which f(D)(max) occurs) with increasing glow peak temperature, and (iii) decreased effects of radiation damage with increasing glow peak temperature. The UNIM interpretation of this behaviour requires both strongly decreasing values of ks (the relative contribution of localised recombination) as a function of glow peak temperature and, as well, significantly different values of the dose-filling constants of the trapping centre (TC) and LC for peaks 7 and 8 than those used for peaks 4 and 5. This suggests that different TC/LC configurations are responsible for HTTL. The relative intensity of peak 5a (a low-temperature satellite of peak 5 arising from localised recombination) was found to significantly increase at higher dose levels due to preferential electron and hole population of the trapping/recombination complex giving rise to composite glow peak 5. It is also demonstrated that possible changes in the trapping cross section of the LC and the competitive centres due to increasing sample/glow peak temperature do not significantly influence these observations/conclusions.
12: Journal of visualized experiments : JoVE, 2009, 30(33)
The use of SC1 (Pluripotin) to Support mESC Self-renewal in the Absence of LIF.
[Abstract]Mouse embryonic stem (ES) cells are conventionally cultured with Leukemia Inhibitory Factor (LIF) to maintain self-renewal.(1) However, LIF is expensive and activation of the LIF/JAK/STAT3 pathway is not absolutely required to maintain the self-renewal state.(2) The SC1 small molecule may be an economical alternative to LIF. SC1 functions through dual inhibition of Ras-GAP and ERK1.(3) Illustration of its mechanism of action makes it a useful tool to study the fundamental molecular mechanism of self-renewal. Here we demonstrate the procedure for culturing mouse ES cells in the presence of SC1 and show that they are able to maintain self-renewal in the absence of LIF. Cells cultured with SC1 showed similar morphology compared to cells maintained with LIF. Both exhibited typical mouse ES morphology after five passages. Expression of typical pluripotency markers (Oct4, Sox2, Nanog, and SSEA1) was observed after five passages in the presence of SC1. Furthermore, SC1 caused no overt toxicity on mouse ES cells.
13: Cellular signalling, 2009 Nov 13, 30(33)
PPARgamma regulates LIF-induced growth and self-renewal of mouse ES cells through Tyk2-Stat3 pathway.
[Abstract]Embryonic stem (ES) cells are genetically normal, pluripotent cells, capable of self-renewal and multi-lineage differentiation. Leukemia inhibitory factor (LIF) is a growth factor that can maintain the pluripotency of mouse ES cells in culture. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor transcription factors that regulate growth and differentiation of many cell types. We have shown earlier that 15-Deoxy-(12,14)-Prostaglandin J2 (15d-PGJ2), a natural ligand for PPARgamma, inhibits LIF-induced proliferation of mouse ES cells in culture. In this study we demonstrate that the PPARgamma antagonist Bisphenol A diglycidyl ether (BADGE) and 2-Chloro-5-nitro-N-(4-pyridyl)benzamide (T0070907) reverse the inhibition of ES cell proliferation by PPARgamma agonists. Stable transfection of ES cells with a dominant negative PPARgamma1 mutant also reduced the inhibition of proliferation by PPARgamma agonists. While 15d-PGJ2 and ciglitazone induced growth-arrest in ES cells by blocking LIF signaling, PPARgamma antagonists and dominant negative PPARgamma1 mutant reversed proliferation by restoring LIF-induced Tyk2-Stat3 signaling. These results suggest that PPARgamma regulates LIF-induced growth and self-renewal of mouse ES cells through Tyk2-Stat3 pathway.
14: Reproduction (Cambridge, England), 2009 Jul 27, 76(8)
Determining the LIF-sensitive period for implantation using a LIFR antagonist.
[Abstract]Uteri of
15: PloS one, 2009, 4(7)
LIF-free embryonic stem cell culture in simulated microgravity.
[Abstract]BACKGROUND: Leukemia inhibitory factor (LIF) is an indispensable factor for maintaining mouse embryonic stem (ES) cell pluripotency. A feeder layer and serum are also needed to maintain an undifferentiated state, however, such animal derived materials need to be eliminated for clinical applications. Therefore, a more reliable ES cell culture technique is required. METHODOLOGY/PRINCIPAL FINDINGS: We cultured mouse ES cells in simulated microgravity using a 3D-clinostat. We used feeder-free and serum-free media without LIF. CONCLUSIONS/SIGNIFICANCE: Here we show that simulated microgravity allows novel LIF-free and animal derived material-free culture methods for mouse ES cells.
16: Electrophoresis, 2009 Jul, 30(13)
Separation of free amino acids and catecholamines in human plasma and rabbit vitreous samples using a new fluorogenic reagent 3-(4-bromobenzoyl)-2-quinolinecarboxaldehyde with CE-LIF detection.
[Abstract]A sensitive and efficient analysis of amino acids and catecholamines is currently presented with 3-(4-bromobenzoyl)-2-quinolinecarboxaldehyde as a fluorogenic derivatization reagent using CE separation with LIF detection. For good derivatization conditions, the reagent concentrations, pH value, temperature, and reaction time were explored, which were followed by the derivatization reaction in stable yield. The optimal running buffer was composed of mixtures involving 120 mM, pH 9.1 boric acid, 38.5 mM SDS, and 19% ACN v/v. The LOD (S/N=3) was found as low as 0.65 nM. The proposed method was validated by the two-order-magnitude linearity and correlation coefficient ranging from 0.9957 to 0.9998. The accuracy and specificity of this assay were also assured from the spiking of real samples with a standard known concentration. In order to demonstrate its wide range of applications, the method has been applied to the analysis of both human plasma and rabbit vitreous samples.
17: Nature, 2009 Jul 2, 460(7251)
A parallel circuit of LIF signalling pathways maintains pluripotency of mouse ES cells.
[Abstract]The cytokine leukaemia inhibitory factor (LIF) integrates signals into mouse embryonic stem (ES) cells to maintain pluripotency. Although the Jak-Stat3 pathway is essential and sufficient to mediate LIF signals, it is still unclear how these signals are linked to the core circuitry of pluripotency-associated transcription factors, consisting of Oct3/4 (also called Pou5f1), Sox2 and Nanog. Here we show that two LIF signalling pathways are each connected to the core circuitry via different transcription factors. In mouse ES cells, Klf4 is mainly activated by the Jak-Stat3 pathway and preferentially activates Sox2, whereas Tbx3 is preferentially regulated by the phosphatidylinositol-3-OH kinase-Akt and mitogen-activated protein kinase pathways and predominantly stimulates Nanog. In the absence of LIF, artificial expression of Klf4 or Tbx3 is sufficient to maintain pluripotency while maintaining the expression of Oct3/4. Notably, overexpression of Nanog supports LIF-independent self-renewal of mouse ES cells in the absence of Klf4 and Tbx3 activity. Therefore, Klf4 and Tbx3 are involved in mediating LIF signalling to the core circuitry but are not directly associated with the maintenance of pluripotency, because ES cells keep pluripotency without their expression in the particular context.
18: Electrophoresis, 2009 Jul, 30(13)
Assay of bradykinin metabolites in human body fluids by CE-LIF coupled with transient ITP preconcentration.
[Abstract]A CE with LIF detection was developed for the separation and determination of three bradykinin (BK) metabolites: BK2-9, BK1-7 and BK1-5. BK fragments were derivatized with 5-(4, 6-dichloro-s-triazin-2-ylamino) fluorescein before CE-LIF analysis. Eighty millimolar of Tris-H3PO4 (pH 9.0) was selected as the derivatization media. Three BK fragments were baseline separated within 10 min by using 0.2 M TAPS-Tris buffer (pH 8.5) as the running buffer. Meanwhile we have also developed a simple, quick, and sensitive on-column transient ITP preconcentration for CE-LIF detection of three BK fragments. Ten millimolar of Tris-HCl (pH 9.0) was chosen as the leading electrolyte and 0.2 M TAPS-Tris (pH 8.5) containing 10 mM 1-butyl-3-methylimidazolium tetrafluoroborate as the terminating electrolyte and also served as the running buffer during CZE separation. By using this transient ITP coupled with CE-LIF, concentration detection limits (S/N=3) for BK2-9, BK1-7 and BK1-5 were 0.3, 0.1 and 0.1 pmol/L, respectively. This method has been applied to the assay of human saliva and plasma samples with satisfactory results.
19: Stem cells (Dayton, Ohio), 2009 Sep, 27(9)
Abrogation of E-cadherin-mediated cell-cell contact in mouse embryonic stem cells results in reversible LIF-independent self-renewal.
[Abstract]We have previously demonstrated that differentiation of embryonic stem (ES) cells is associated with downregulation of cell surface E-cadherin. In this study, we assessed the function of E-cadherin in mouse ES cell pluripotency and differentiation. We show that inhibition of E-cadherin-mediated cell-cell contact in ES cells using gene knockout (Ecad(-/-)), RNA interference (EcadRNAi), or a transhomodimerization-inhibiting peptide (CHAVC) results in cellular proliferation and maintenance of an undifferentiated phenotype in fetal bovine serum-supplemented medium in the absence of leukemia inhibitory factor (LIF). Re-expression of E-cadherin in Ecad(-/-), EcadRNAi, and CHAVC-treated ES cells restores cellular dependence to LIF supplementation. Although reversal of the LIF-independent phenotype in Ecad(-/-) ES cells is dependent on the beta-catenin binding domain of E-cadherin, we show that beta-catenin null (betacat(-/-)) ES cells also remain undifferentiated in the absence of LIF. This suggests that LIF-independent self-renewal of Ecad(-/-) ES cells is unlikely to be via beta-catenin signaling. Exposure of Ecad(-/-), EcadRNAi, and CHAVC-treated ES cells to the activin receptor-like kinase inhibitor SB431542 led to differentiation of the cells, which could be prevented by re-expression of E-cadherin. To confirm the role of transforming growth factor beta family signaling in the self-renewal of Ecad(-/-) ES cells, we show that these cells maintain an undifferentiated phenotype when cultured in serum-free medium supplemented with Activin A and Nodal, with fibroblast growth factor 2 required for cellular proliferation. We conclude that transhomodimerization of E-cadherin protein is required for LIF-dependent ES cell self-renewal and that multiple self-renewal signaling networks subsist in ES cells, with activity dependent upon the cellular context.
20: European cytokine network, 2009 Jun 1, 20(2)
The LIF cytokine: towards adulthood.
[Abstract]The aim of this article is to recapitulate the key features of leukaemia inhibitory factor cytokine (LIF), to review its numerous physiological effects and to comment on the most recent data. We will also present results of transcriptome analyses, which have highlighted different categories of LIF targets, identified in murine embryonic stem (ES) cells and early derivatives. We hope to stimulate new research fields on this puzzling cytokine, which, forty years after its discovery, has still not disclosed all its secrets.
21: PloS one, 2009, 4(6)
N-Myc regulates expression of pluripotency genes in neuroblastoma including lif, klf2, klf4, and lin28b.
[Abstract]myc genes are best known for causing tumors when overexpressed, but recent studies suggest endogenous myc regulates pluripotency and self-renewal of stem cells. For example, N-myc is associated with a number of tumors including neuroblastoma, but also plays a central role in the function of normal neural stem and precursor cells (NSC). Both c- and N-myc also enhance the production of induced pluripotent stem cells (iPSC) and are linked to neural tumor stem cells. The mechanisms by which myc regulates normal and neoplastic stem-related functions remain largely open questions. Here from a global, unbiased search for N-Myc bound genes using ChIP-chip assays in neuroblastoma, we found lif as a putative N-Myc bound gene with a number of strong N-Myc binding peaks in the promoter region enriched for E-boxes. Amongst putative N-Myc target genes in expression microarray studies in neuroblastoma we also found lif and three additional important embryonic stem cell (ESC)-related factors that are linked to production of iPSC: klf2, klf4, and lin28b. To examine the regulation of these genes by N-Myc, we measured their expression using neuroblastoma cells that contain a Tet-regulatable N-myc transgene (TET21N) as well as NSC with a nestin-cre driven N-myc knockout. N-myc levels closely correlated with the expression of all of these genes in neuroblastoma and all but lif in NSC. Direct ChIP assays also indicate that N-Myc directly binds the lif promoter. N-Myc regulates trimethylation of lysine 4 of histone H3 in the promoter of lif and possibly in the promoters of several other stem-related genes. Together these findings indicate that N-Myc regulates overlapping stem-related gene expression programs in neuroblastoma and NSC, supporting a novel model by which amplification of the N-myc gene may drive formation of neuroblastoma. They also suggest mechanisms by which Myc proteins more generally contribute to maintenance of pluripotency and self-renewal of ESC as well as to iPSC formation.
22: Molecular reproduction and development, 2009 Aug, 76(8)
Regulating effect of LIF on the expression of FuT7: Probe into the mechanism of sLe(x) in implantation.
[Abstract]The emission of negative cluster ions produced by the impact of approximately 60 MeV (252)Cf fission fragments on a (7)LiF polycrystalline target is analyzed. The negative ion mass spectrum is dominated by the ((7)LiF)(n)F(-) series, n = 1 to approximately 30. The desorption yield distribution of the ((7)LiF)(n)F(-) members has a maximum at n = 2 and then decreases as the sum of two exponentials whose decay parameters are k(Fast) = 0.9 and k(Slow) = 0.08. These k values are the same as those observed for the positive series and close to others obtained for condensed gas targets. Relative cluster ion stabilities, deduced from the experimental ion abundances for the (LiF)(n)F(-) series, are proposed to be correlated with theoretical structures according to their internal energy by using the deviation plot (D-plot) methodology. A pool of candidate cluster structures was generated using a genetic algorithm and further analyzed and optimized using density functional theory (DFT) with the hybrid functional B3LYP (DFT/B3LYP) and Moller-Plesset perturbation theory (MP2). For the small clusters (n = 1 to 2), the most stable structures are found to be linear, whereas the larger clusters (n = 4 to 6) present cubic or polyhedral structures. Fragmentation energies, ionization potentials, and relative stabilities are reported for the most abundant families of the (LiF)(n)F(-) and (LiF)(n)(-) series.
23: Journal of computational chemistry, 2009 Dec, 30(16)
All-electron LCAO calculations of the LiF crystal phonon spectrum: Influence of the basis set, the exchange-correlation functional, and the supercell size.
[Abstract]For the first time the convergence of the phonon frequencies and dispersion curves in terms of the supercell size is studied in ab initio frozen phonon calculations on LiF crystal. Helmann-Feynman forces over atomic displacements are found in all-electron calculations with the localized atomic functions (LCAO) basis using CRYSTAL06 program. The Parlinski-Li-Kawazoe method and FROPHO program are used to calculate the dynamical matrix and phonon frequencies of the supercells. For fcc lattice, it is demonstrated that use of the full supercell space group (including the supercell inner translations) enables to reduce essentially the number of the displacements under consideration. For Hartree-Fock (HF), PBE and hybrid PBE0, B3LYP, and B3PW exchange-correlation functionals the atomic basis set optimization is performed. The supercells up to 216 atoms (3 x 3 x 3 conventional unit cells) are considered. The phonon frequencies using the supercells of different size and shape are compared. For the commensurate with supercell k-points the best agreement of the theoretical results with the experimental data is found for B3PW exchange-correlation functional calculations with the optimized basis set. The phonon frequencies at the most non-commensurate k-points converged for the supercell consisting of 4 x 4 x 4 primitive cells and ensures the accuracy 1-2% in the thermodynamic properties calculated (the Helmholtz free energy, entropy, and heat capacity at the room temperature).
24: Experimental cell research, 2009 Jul 15, 315(12)
Basic FGF and Activin/Nodal but not LIF signaling sustain undifferentiated status of rabbit embryonic stem cells.
[Abstract]Recently, we proposed that rabbit embryonic stem (ES) cells can be stable mammalian ES cells and can be a small animal model for human ES cell research. However, the signaling pathways controlling rabbit ES cell pluripotency remain largely unknown. Here we report that bFGF can maintain the undifferentiated status of rabbit ES cells and found that Activin/Nodal signaling through Smad2/3 activation is necessary to maintain the pluripotent status of rabbit ES cells. We further show that in spite of STAT3 in rabbit ES cells, LIF is dispensable for maintenance of undifferentiated status in rabbit ES cells. Although phosphorylation of Janus Kinase signal transducer and activator (JAK/STAT) disappeared after JAK-inhibitor treatment, OCT4 is constantly produced. When rabbit ES cells were cultured for more than 40 passages in the absence of LIF, expression of stem cell markers and teratoma formation were observed. Additionally, treatment with Rho-associated kinase (ROCK) inhibitor, Y27632, to rabbit ES cells significantly enhanced cell growth. These findings suggest that molecular mechanisms underlying rabbit ES cell self-renewal and pluripotency are similar to primate ES cells. Rabbit ES cells may provide a translational research model for the study of human diseases in vitro and applications to transplantation therapy.
25: BMC ophthalmology, 2009 Feb 23, 9(1)
CD133+ adult human retinal cells remain undifferentiated in Leukemia Inhibitory Factor (LIF).
[Abstract]ABSTRACT: BACKGROUND: CD133 is a cell surface marker of haematopoietic stem and progenitor cells. Leukaemia inhibitory factor (LIF), sustains proliferation and not differentiation of embryonic stem cells. We used CD133 to purify adult human retinal cells and aimed to determine what effect LIF had on these cultures and whether they still had the ability to generate neurospheres. METHODS: Retinal cell suspensions were derived from adult human post-mortem tissue with ethical approval. With magnetic automated cell sorting (MACS) CD133+ retinal cells were enriched from post mortem adult human retina. CD133+ retinal cell phenotype was analysed by flow cytometry and cultured cells were observed for proliferative capacity, neuropshere generation and differentiation with or without LIF supplementation. RESULTS: We demonstrated purification (to 95%) of CD133+ cells from adult human postmortem retina. Proliferating cells were identified through BrdU incorporation and expression of the proliferation markers Ki67 and Cyclin D1. CD133+ retinal cells differentiated whilst forming neurospheres containing appropriate lineage markers including glia, neurons and photoreceptors. LIF maintained CD133+ retinal cells in a proliferative and relatively undifferentiated state (Ki67, Cyclin D1 expression) without significant neurosphere generation. Differentiation whilst forming neurospheres was re-established on LIF withdrawal. CONCLUSIONS: These data support the evidence that CD133 expression characterises a population of cells within the resident adult human retina with progenitor cell properties and that their turnover and differentiation is influenced by LIF. This may explain differences in retinal responses observed following disease or injury.
26: Electrophoresis, 2009 Feb 19, 9(1)
Rapid determination of superoxide free radical in hepatocellular carcinoma cells by MCE with LIF.
[Abstract]A method for determination of superoxide free radical (O(2) (-*)) based on MCE with LIF was developed. Fluorescent reagent 2-chloro-1, 3-dibenzothiazolinecyclohexene, which was synthesized in our laboratory, was employed as the labeling reagent, the highest derivatization efficiency was obtained in 20 mM HEPES buffer (pH 7.4) for 10 min at 37 degrees C. Optimal determination of O(2) (-*) was achieved on a glass microchip, using 50 mM HEPES buffer (pH 7.4). Under the optimized conditions, linearity of response was obtained in the range of 4.0x10(-7)-1.0x10(-5) M, the detection limit (S/N=3) was 0.15 muM, the RSDs of migration time and peak area were 2.6 and 3.8%, respectively. Interference experiment was investigated and the result indicates that 1000-fold molar excess of hydrogen peroxide does not interfere with the determination of O(2) (-*) in complex system. Finally, the method has been successfully applied to determine O(2) (-*) in hepatocellular carcinoma cells as well as phorbol 12-myristate 13-acetate stimulated RAW264.7 macrophages. The average recoveries were 97.3 and 98.6%, respectively.
27: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine, 2009 Jan 18, 9(1)
Further studies on higher temperature TL glow peaks of (7)LiF:Mg,Ti.
[Abstract]Thermoluminescence (TL) characteristics of the higher temperature peaks of LiF:Mg,Ti, which exhibit a unique property of high relative response to high LET radiation, were studied in view of some recent findings and discussions. By making separate readouts of dosimetric peaks (mainly peak 5) and higher temperature peaks (mainly peak 7), the precision in TL measurements, reusability and, fading were found comparable for the TL readouts in the two regions. However, the intensity of higher temperature peaks was found to be susceptible to the annealing treatments. In the standard annealing treatment of LiF:Mg,Ti, namely, 400 degrees C for 1h followed by 100 degrees C for 2h, the intensity of the higher temperature glow peaks was significantly affected when the second step of lower temperature annealing treatment at 100 degrees C for 2h was not used. The dose response function f(D) of higher temperature peaks to gamma rays in the range from 30 to 150mGy was found to be within about 10% (-4 and +9%) but above 200mGy it increased sharply. The intricacies of dosimetry of mixed fields of low and high LET radiation are discussed.
28: The journal of physical chemistry. A, 2009 Feb 10, 9(1)
A Theoretical and Experimental Study of Positive and Neutral LiF Clusters Produced by Fast Ion Impact on a Polycrystalline LiF Target.
[Abstract]The positive and neutral clusters produced by the impact of approximately 60 MeV (252)Cf fission fragments on a LiF polycrystalline target are analyzed. The positive ion spectrum is dominated by the (LiF)(n)Li(+) series, n = 0-7, exhibiting a total yield 2 orders of magnitude higher than that of the (LiF)(n)(+) series. The yield for the dominant (LiF)(n)Li(+) series decreases roughly as exp(-kn), where k approximately 0.9 for n = 0-3 and k approximately 0.6 for the heavier clusters (n = 4-9), while the yield of the (LiF)(n)(+) series also decreases exponentially as n increases with k approximately 0.6. Theoretical calculations were performed for the (LiF)(n)Li(0), (LiF)(n)Li(+), and (LiF)(n)(0) series for n up to 9. For the smaller clusters the structures first obtained with a genetic algorithm generator were further optimized at the DFT/B3LYP/6-311+G(3df), DFT/B3LYP/LACV3P*, and MP2/LACV3P* levels of theory. An energy criterion is used for a proper taxonomic description of the optimized cluster isomers. Cluster properties such as fragmentation energy and stability are discussed for the proposed configurations. The results show that for all three series the most stable isomers present a linear structure for small cluster size (n = 1-3), while cubic cells or polyhedral structures are preferred for larger cluster sizes (n = 4-9). Fragmentation energy results suggest that a desorbed excited (LiF)(n)Li(+) ion preferentially dissociates via a cascade of (LiF)(n)(0) units, in agreement with the slope modification in the exponential decay of the (LiF)(n)Li(+) ion abundances for n >/= 3.