The Effect of Exposed Facets of Ceria to the Nickel Species in Nickel-Ceria Catalysts and Their Performance in a NO + CO Reaction

CeO2 rods with {110} facets and cubes with {100} facets were utilized as catalyst supports to probe the effect of crystallographic facets on the nickel species and the structure-dependent catalytic performance. Various analysis methods (ex and in situ XRD, TEM, Raman, XPS, TPR, TPD) were used to investigate the structural forms of the catalysts, and these results indicated that the deposition of nickel species resulted in the formation of two main active types of the catalyst components: NiO strongly or weakly interacted with the surface and Ni-Ce-O solid solution. Notably, the states and distribution ratio of nickel species were related to the shape of CeO2. It was found that CeO2 rods had more active sites to coordinate with nickel species to form a strong interaction with NiO on the surface and a more stable construction when compared to cubes. Furthermore, the nickel-ceria catalysts with rod shape were more active towards NO oxidation with complete conversion below 191 °C, but for cube shape, complete conversion occurred above 229 °C (e.g., for nickel loading of ∼5%, the complete conversion temperature was 154 °C for the rod shape and 229 °C for the cube shape). On the basis of the analysis of the catalysts structure, the superior catalytic activity was due to a combination of surface structures of NiO (mainly strongly interacting with the surface) and nickel ions Ni(2+) in the Ni-Ce-O bulk phase.

Characterization of mutations in streptomycin-resistant Mycobacterium tuberculosis isolates in Sichuan, China and the association between Beijing-lineage and dual-mutation in gidB

Mutations in rpsL, rrs, and gidB are well linked to streptomycin (STR) resistance, some of which are suggested to be potentially associated with Mycobacterium tuberculosis genotypic lineages in certain geographic regions. In this study, we aimed to investigate the mutation characteristics of streptomycin resistance and the relationship between the polymorphism of drug-resistant genes and the lineage of M. tuberculosis isolates in Sichuan, China. A total of 227 M. tuberculosis clinical isolates, including 180 STR-resistant and 47 pan-susceptible isolates, were analyzed for presence of mutations in the rpsL, rrs and gidB loci. Mutation K43R in rpsL was strongly associated with high-level streptomycin resistance (P < 0.01), while mutations in rrs and gidB potentially contributed to low-level resistance (P < 0.05). No general association was exhibited between STR resistance and Beijing genotype, however, in STR-resistant strains, Beijing genotype was significantly correlated with high-level STR resistance, as well as the rpsL mutation K43R (P < 0.01), indicating that Beijing genotype has an evolutionary advantage under streptomycin pressure. Notably, in all isolates of Beijing genotype, a dual mutation E92D (a276c) and A205A (a615g) in gidB was detected, suggesting a highly significant association between this dual mutation and Beijing genotype.

[EFFECT OF INHIBITOR OF DIFFERENTIATION 1 GENE TRANSFECTION ON BONE MORPHOGENETIC PROTEIN 2 PROMOTING CHONDROGENIC GENE EXPRESSIONS OF RABBIT INTERVERTEBRAL CARTILAGE ENDPLATE CELLS]

OBJECTIVE

To study the effect of inhibitor of differentiation 1 (Id1) gene transfection on bone morphogenetic protein 2 (BMP-2) promoting the expressions of collagen type II (COL II) and aggrecan (ACAN) in intervertebral cartilage endplate cells (EPCs).

METHODS

EPCs were harvested from the New Zealand white rabbits, the 2nd generation EPCs were used for experiment. The transfection efficiency of green fluorescent protein blank lentivirus, high expression of Id1 lentivirus, RNA interference (RNAi) Id1 lentivirus transfection in the EPCs were observed by the fluorescence microscopy, real-time fluorescence quantitative PCR, and Western blot. Blank vector, single BMP-2 gene, BMP-2 and Id1 genes were transfected into EPCs, respectively. The cell morphology and the expressions of COL II and ACAN in each group were observed.

RESULTS

Lentiviral transfection had no significant effect on the cell morphology. The EPCs were effectively transfected by the high expression Id1 lentivirus and RNAi Id1 lentivirus; the expression of Id1 mRNA was also significantly interfered. The expressions of COL II and ACAN mRNA and synthesis of COL II and ACAN protein were significantly higher in BMP-2 lentivirus and high expression Id1 lentivirus groups than control group (P < 0.05). The expression of COL II and ACAN protein were down regulated in the cartilage endplate cells when the expression of Id1 gene was decreased (P < 0.05).

CONCLUSION

Up-regulation of Id1 gene expression can enhance the effects of BMP-2 on the synthesis of COL II and ACAN in EPCs.

ESC-Derived Basal Forebrain Cholinergic Neurons Ameliorate the Cognitive Symptoms Associated with Alzheimer's Disease in Mouse Models

Degeneration of basal forebrain cholinergic neurons (BFCNs) is associated with cognitive impairments of Alzheimer’s disease (AD), implying that BFCNs hold potentials in exploring stem cell-based replacement therapy for AD. However, studies on derivation of BFCNs from embryonic stem cells (ESCs) are limited, and the application of ESC-derived BFCNs remains to be determined. Here, we report on differentiation approaches for directing both mouse and human ESCs into mature BFCNs. These ESC-derived BFCNs exhibit features similar to those of their in vivo counterparts and acquire appropriate functional properties. After transplantation into the basal forebrain of AD model mice, ESC-derived BFCN progenitors predominantly differentiate into mature cholinergic neurons that functionally integrate into the endogenous basal forebrain cholinergic projection system. The AD mice grafted with mouse or human BFCNs exhibit improvements in learning and memory performances. Our findings suggest a promising perspective of ESC-derived BFCNs in the development of stem cell-based therapies for treatment of AD.

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Mouse and human ESCs differentiate into basal forebrain cholinergic neurons (BFCNs)

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ESC-derived BFCNs exhibit functional properties in vitro and transplanted in vivo

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ESC-derived BFCNs functionally integrate into the basal forebrain of AD mice

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The AD model mice grafted with BFCNs exhibit improvements in cognitive abilities

Fra-1 is upregulated in gastric cancer tissues and affects the PI3K/Akt and p53 signaling pathway in gastric cancer

Gastric cancer is an aggressive disease that continues to have a daunting impact on global health. Fra-1 (FOSL1) plays important roles in oncogenesis in various malignancies. We investigated the expression of Fra-1 in gastric cancer (GC) tissues by qPCR, immunohistochemistry (IHC) and western blot technologies. The results showed that Fra-1 was overexpressed in gastric cancer tissues compared with the adjacent non‑cancerous tissues. To explore the possible mechanism of Fra-1 in GC, we elucidated the effect of Fra-1 in the apoptosis and cell cycle of gastric cancer cells, AGS, and found that a considerable decrease in apoptotic cells and increase of S phase rate were observed for AGS cells with Fra-1 overexpession. We identified and confirmed that Fra-1 affected the expression level of CTTN and EZR in vitro through LC-MS/MS analyses and western blot technology. Furthermore, we found that Fra-1 was correlated with dysregulation PI3K/Akt and p53 signaling pathway in gastric cancer tissues in vitro. Moreover, we found that Fra-1 overexpression affected the expression of PI3K, Akt, MDM2 and p53 in vivo. In summary, our results suggest that Fra-1 is upregulated in gastric cancer tissues and plays its function by affecting the PI3K/Akt and p53 signaling pathway in gastric cancer.

CD90 is upregulated in gastric cancer tissues and inhibits gastric cancer cell apoptosis by modulating the expression level of SPARC protein

Cluster of differentiation 90 (CD90) (Thy-1) plays important roles in the oncogenesis in various types of malignancies. In the present study, we investigated the expression of CD90 in gastric cancer (GC) tissues by q-PCR, immunohistochemistry (IHC), and western blot technologies. The results showed that CD90 was overexpressed in gastric cancer tissues compared with the level in the adjacent non‑cancerous tissues. To explore the possible mechanism of CD90 in GC, we elucidated the effect of CD90 on the apoptosis of AGS gastric cancer cells, and found that a considerable decrease in apoptotic cells was observed for AGS cells with CD90 overexpression. Meanwhile, the rate of apoptotic cells was increased in the AGS cells with CD90 interference (siCD90) compared with that in the AGS cells. Cell apoptosis is closely related to a reduction in mitochondrial membrane potential (ΔΨm) and an increase in intracellular reactive oxygen species (ROS) and calcium ion (Ca2+) concentrations. Our results showed that overexpression of CD90 in the AGS gastric cancer cells led to an increase in ΔΨm and a decrease in intracellular ROS and Ca2+ concentrations. At the same time, siCD90 reduced ΔΨm and the increase in intracellular ROS and Ca2+ concentrations. Furthermore, we identified and confirmed that CD90 functions by modulating the expression level of secreted protein, acidic, cysteine‑rich (osteonectin) (SPARC) in vitro through LC‑MS/MS analyses and western blot technology. In summary, our results suggest that CD90 is upregulated in gastric cancer and inhibits gastric cancer cell apoptosis by modulating the expression level of SPARC protein.

Upregulated long non-coding RNA AFAP1-AS1 expression is associated with progression and poor prognosis of nasopharyngeal carcinoma

Altered expression of long noncoding RNAs (lncRNAs) associated with human carcinogenesis. We performed a cDNA microarray analysis of lncRNA expression in 12 cases of nasopharyngeal carcinoma (NPC) and 4 non-tumor nasopharyngeal epitheliums. One lncRNA, actin filament associated protein 1 antisense RNA1 (AFAP1-AS1), was identified and selected for further study. AFAP1-AS1 expression was upregulated in NPC and associated with NPC metastasis and poor prognosis. In vitro experiments demonstrated that AFAP1-AS1 knockdown significantly inhibited the NPC cell migration and invasive capability. AFAP1-AS1 knockdown also increased AFAP1 protein expression. Proteomic and bioinformatics analyses suggested that AFAP1-AS1 affected the expression of several small GTPase family members and molecules in the actin cytokeratin signaling pathway. AFAP1-AS1 promoted cancer cell metastasis via regulation of actin filament integrity. AFAP1-AS1 might be a potential novel marker that can predict cancer patient prognosis and as a potential therapeutic target for NPC.

Improving Estimation of Distribution Algorithm on Multimodal Problems by Detecting Promising Areas

In this paper, a novel multiple sub-models maintenance technique, named maintaining and processing sub-models (MAPS), is proposed. MAPS aims to enhance the ability of estimation of distribution algorithms (EDAs) on multimodal problems. The advantages of MAPS over the existing multiple sub-models based EDAs stem from the explicit detection of the promising areas, which can save many function evaluations for exploration and thus accelerate the optimization speed. MAPS can be combined with any EDA that adopts a single Gaussian model. The performance of MAPS has been assessed through empirical studies where MAPS is integrated with three different types of EDAs. The experimental results show that MAPS can lead to much faster convergence speed and obtain more stable solutions than the compared algorithms on 12 benchmark problems.

Transcription factors COUP-TFI and COUP-TFII are required for the production of granule cells in the mouse olfactory bulb

Neural stem cells (NSCs) persist in the adult mammalian subventricular zone (SVZ) of the lateral ventricle. Primary NSCs generate rapidly dividing intermediate progenitor cells, which in turn generate neuroblasts that migrate along the rostral migratory stream (RMS) to the olfactory bulb (OB). Here, we have examined the role of the COUP-TFI and COUP-TFII orphan nuclear receptor transcription factors in mouse OB interneuron development. We observed that COUP-TFI is expressed in a gradient of low rostral to high caudal within the postnatal SVZ neural stem/progenitor cells. COUP-TFI is also expressed in a large number of migrating neuroblasts in the SVZ and RMS, and in mature interneurons in the OB. By contrast, very few COUP-TFII-expressing (+) cells exist in the SVZ-RMS-OB pathway. Conditional inactivation of COUP-TFI resulted in downregulation of tyrosine hydroxylase expression in the OB periglomerular cells and upregulation of COUP-TFII expression in the SVZ, RMS and OB deep granule cell layer. In COUP-TFI/COUP-TFII double conditional mutant SVZ, cell proliferation was increased through the upregulation of the proneural gene Ascl1. Furthermore, COUP-TFI/II-deficient neuroblasts had impaired migration, resulting in ectopic accumulation of calretinin (CR)+ and NeuN+ cells, and an increase in apoptotic cell death in the SVZ. Finally, we found that most Pax6+ and a subset of CR+ granular cells were lost in the OB. Taken together, these results suggest that COUP-TFI/II coordinately regulate the proliferation, migration and survival of a subpopulation of Pax6+ and CR+ granule cells in the OB.

Brief Report: Human Mesenchymal Stem-Like Cells Facilitate Floating Tumorigenic Cell Growth via Glutamine-Ammonium Cycle

How mesenchymal stem cells (MSCs) promote tumor growth remains incompletely understood. Here, we show that mesenchymal stem-like cells (MSLCs) are commonly present in malignant pleural effusion or ascites of cancer patients, where they directly interact with tumor cells. Chemokines and chemokine receptors, especially the CCL2/CCR2 pathway, are involved in this interaction. As a result, MSLCs exert tumor-promoting effects by enhancing the proliferation and colony formation of tumor-repopulating cells. The underlying molecular basis involves MSLC release of glutamine to tumorigenic cells. Inhibition of glutamine uptake impedes MSC-mediated tumor-promoting effects. More intriguingly, MSLCs take up tumor cell-released ammonium that, in turn, favors MSLC growth. Thus, glutamine and ammonium form a vicious cycle between MSLCs and tumorigenic cells. These findings suggest a potential clinical application by targeting MSLCs in patients with malignant pleural effusions or ascites.

Ectodermal progenitors derived from epiblast stem cells by inhibition of Nodal signaling

The ectoderm has the capability to generate epidermis and neuroectoderm and plays imperative roles during the early embryonic development. Our recent study uncovered a region with ectodermal progenitor potential in mouse embryo at embryonic day 7.0 and revealed that Nodal inhibition is essential for its formation. Here, we demonstrate that through brief inhibition of Nodal signaling in vitro, mouse embryonic stem cell (ESC)-derived epiblast stem cells (ESD-EpiSCs) could be committed to transient ectodermal progenitor populations, which possess the ability to give rise to neural or epidermal ectoderm in the absence or presence of BMP4, respectively. Mechanistic studies reveal that BMP4 recruits distinct transcriptional targets in ESD-EpiSCs and ectoderm-like cells. Furthermore, FGF-Erk signaling may also be alleviated during the generation of ectoderm-like cells. Thus, our data suggest that instructive interactions among several extracellular signals participate in the commitment of ectoderm from ESD-EpiSCs, which shed new light on the understanding of the formation of ectoderm during the gastrulation in early mouse embryo development.

Lipid mediator lipoxin A4 inhibits tumor growth by targeting IL-10-producing regulatory B (Breg) cells

Lipoxin A4 (LXA4), an arachidonic acid-derived anti-inflammatory lipid mediator, shows anti-tumor potential by regulating tumor immune microenvironments. However, the underlying molecular and cellular basis of this function remains unclear. IL-10-producing B (Breg) cells display tumor-promoting effects by negatively regulating anti-tumor immunity. Here we show that LXA4 inhibits tumor growth by suppressing the generation of Breg cells in tumor-bearing mice. The administration of LXA4 inhibited the induction of Breg cells. Breg cell deficiency, in turn, resulted in LXA4 losing its anti-tumor properties. Intriguingly, regulatory T (Treg) cells also had a role in this process. Targeting Breg cells by LXA4 decreased the number of Treg cells in draining lymph nodes and tumor tissues as well as enhanced cytotoxic T cell activities. In addition, we further demonstrated that LXA4 inhibited Breg cells through its dephosphorylating STAT3 and ERK. These findings unveil a new anti-tumor mechanism underlying LXA4 targeting Breg cells with potential clinical applications.

The effects of substance p on tendinopathy are dose-dependent: an in vitro and in vivo model study

OBJECTIVES

Substance P (SP) is known to be involved in neuropathic pain, chronic inflammation, and tendinopathy. The present study evaluated the effects of different doses of SP on tendon-derived stem cells (TDSCs) in vitro and tendons in vivo.

METHODS

For the in vitro study, TDSCs cultured in growth medium with different concentrations of SP (negative control, 0.1 nM, and 1.0 nM). The effects of SP on TDSCs were examined with respect to their ability to proliferate and differentiate. For the in vivo study, we injected different doses of SP (saline control, 0.5 nmol, and 5.0 nmol) into rat patella tendons to investigate the effects of SP on tendons.

RESULTS

Low and high doses SP significantly enhanced the proliferation ability of TDSCs. Low-dose of SP induced the expression of tenocyte-related genes; however, high-dose of SP induced the expression of non-tenocyte genes, which was evident by the high expression of PPARγ and collagen type II. In the in vivo study, only high-doses of SP (5.0 nmol) induced the tendinosis-like changes in the patella tendon injection model. Low doses of SP (0.5 nmol) enhanced the tenogenesis compared with saline injection and the high-dose SP group.

CONCLUSIONS

SP enhances the proliferation of TDSCs in vitro and the effects of SP on tendinopathy are dose-dependent in vivo.

The novel anti-neuroblastoma agent PF403, inhibits proliferation and invasion in vitro and in brain xenografts

Neuroblastoma is the most common cancer in infants and the fourth most common cancer in children. Our previous study showed that PF403 had a potent antitumor ability. In the present study, we evaluated the anti-neuroblastoma property of PF403 and investigated the underlying mechanisms. MTT assay, colony formation assay and flow cytometry assay were used to assess cytotoxicity of PF403 on SH-SY5Y cells. Transwell assay was chosen to estimate the anti-invasion ability of PF403 on neuroblastoma cells. The protein expression was detected by western blot analysis. The SH-SY5Y brain xenograft model was used to assess in vivo antitumor activity of PF403. PF403-mediated SH-SY5Y cell death was found to be dose- and time-dependent, and PF403 was able to limit invasion and metastasis of neuroblastoma cells. MRI and pathology analysis proved that the pro-drug of PF403, CAT3, inhibited SH-SY5Y cells in vivo. PF403 decreased expression of phosphorylated FAK, MMP-2 and MMP-9 proteins, and downregulated the activity of PI3K/AKT and Raf/ERK pathways, followed by regulation of the proteins expression of Bcl-2 family, activated caspase-3, -9 and PARP and initiation of apoptosis of neuroblastoma cells. PF403 exerted cytotoxicity against SH-SY5Y neuroblastoma cell both in vitro and in vivo, and inhibited its invasion ability, suggesting PF403 has potential as a new anticancer drug for the treatment of neuroblastoma.

Novel Role for γ-Catenin in the Regulation of Cancer Cell Migration via the Induction of Hepatocyte Growth Factor Activator Inhibitor Type 1 (HAI-1)

γ-catenin (Plakoglobin), a well-described structural protein functioning at the adherens junctions and desmosomes, was shown to be either lost or weakly expressed in non-small cell lung cancer (NSCLC) cells and tumor tissues. However, the tumor suppressive affects of γ-catenin were not fully understood. In this study, we have identified a novel role for the affects of γ-catenin on non-small cell lung cancer (NSCLC) cell migration. Expression of γ-catenin in NSCLC cells resulted in reduced cell migration as determined by both scratch assays and trans-well cell migration assays. Moreover, the affects of γ-catenin on cell migration were observed to be p53-dependent. Mechanistically, the anti-migratory effects seen via γ-catenin were driven by the expression of hepatocyte growth factor activator inhibitor Type I (HAI-1 or SPINT-1), an upstream inhibitor of the c-MET signaling pathway. Furthermore, the re-expression of γ-catenin sensitized NSCLC cells to c-MET inhibitor-mediated growth inhibition. Taken together, we identify γ-catenin as a novel regulator of HAI-1, which is a critical regulator of HGF/c-MET signaling. Therefore, targeting γ-catenin-mediated HAI-1 expression might be a useful strategy to sensitize NSCLC to c-MET inhibitors.

Conformational sampling and structure prediction of multiple interacting loops in soluble and β-barrel membrane proteins using multi-loop distance-guided chain-growth Monte Carlo method

MOTIVATION

Loops in proteins are often involved in biochemical functions. Their irregularity and flexibility make experimental structure determination and computational modeling challenging. Most current loop modeling methods focus on modeling single loops. In protein structure prediction, multiple loops often need to be modeled simultaneously. As interactions among loops in spatial proximity can be rather complex, sampling the conformations of multiple interacting loops is a challenging task.

RESULTS

In this study, we report a new method called multi-loop Distance-guided Sequential chain-Growth Monte Carlo (M-DiSGro) for prediction of the conformations of multiple interacting loops in proteins. Our method achieves an average RMSD of 1.93 Å for lowest energy conformations of 36 pairs of interacting protein loops with the total length ranging from 12 to 24 residues. We further constructed a data set containing proteins with 2, 3 and 4 interacting loops. For the most challenging target proteins with four loops, the average RMSD of the lowest energy conformations is 2.35 Å. Our method is also tested for predicting multiple loops in β-barrel membrane proteins. For outer-membrane protein G, the lowest energy conformation has a RMSD of 2.62 Å for the three extracellular interacting loops with a total length of 34 residues (12, 12 and 10 residues in each loop).

AVAILABILITY AND IMPLEMENTATION

The software is freely available at: tanto.bioe.uic.edu/m-DiSGro.

CONTACT

jinfeng@stat.fsu.edu or jliang@uic.edu

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

[MicroRNAs and nonresolving inflammation-related cancer]

The link between nonresolving inflammation and cancer is well documented. On the one hand, epidemiologic evidence supports that approximately 25% of all human cancer worldwide is caused by nonresolving inflammation. On the other hand, inflammatory cells are found in the microenvironment of most, if not all, tumors. In the tumor micro-environment, inflammatory cells and molecules influence almost every aspect of cancer. MicroRNAs (miRNAs) participate in the initiation and progression of nonresolving inflammation-related cancer by regulating the key genes and related signaling pathways. Further investigation into the molecular mechanisms by which miRNAs carry out their functions will be of great value in the prevention, early diagnosis, and treatment of tumors.

Intrinsic regulations in neural fate commitment

Neural fate commitment is an early embryonic event that a group of cells in ectoderm, which do not ingress through primitive streak, acquire a neural fate but not epidermal or mesodermal lineages. Several extracellular signaling pathways initiated by the secreted proteins bone morphogenetic proteins (BMPs), fibroblast growth factors (FGFs), wingless/int class proteins (WNTs) and Nodal play essential roles in the specification of the neural plate. Accumulating evidence from the studies on mouse and pluripotent embryonic stem cells reveals that except for the extracellular signals, the intracellular molecules, including both transcriptional and epigenetic factors, participate in the modulation of neural fate commitment as well. In the review, we mainly focus on recent findings that the initiation of the nervous system is elaborately regulated by the intrinsic programs, which are mediated by transcriptional factors such as Sox2, Zfp521, Sip1 and Pou3f1, as well as epigenetic modifications, including histone methylation/demethylation, histone acetylation/deacetylation, and DNA methylation/demethylation. The discovery of the intrinsic regulatory machineries provides better understanding of the mechanisms by which the neural fate commitment is ensured by the cooperation between extracellular factors and intracellular molecules.

Upregulation of cytosolic phosphoenolpyruvate carboxykinase is a critical metabolic event in melanoma cells that repopulate tumors

Although metabolic defects have been investigated extensively in differentiated tumor cells, much less attention has been directed to the metabolic properties of stem-like cells that repopulate tumors [tumor-repopulating cells (TRC)]. Here, we show that melanoma TRCs cultured in three-dimensional soft fibrin gels reprogram glucose metabolism by hijacking the cytosolic enzyme phosphoenolpyruvate carboxykinase (PCK1), a key player in gluconeogenesis. Surprisingly, upregulated PCK1 in TRCs did not mediate gluconeogenesis but promoted glucose side-branch metabolism, including in the serine and glycerol-3-phosphate pathways. Moreover, this retrograde glucose carbon flow strengthened rather than antagonized glycolysis and glucose consumption. Silencing PCK1 or inhibiting its enzymatic activity slowed the growth of TRCs in vitro and impeded tumorigenesis in vivo. Overall, our work unveiled metabolic features of TRCs in melanoma that have implications for targeting a unique aspect of this disease.

Further studies on the role of dopants in LiF:Mg,Cu,Si thermoluminescent material

The 3-D thermoluminescence spectra and glow curves of LiF:Mg,Cu,Si, LiF:Mg,Cu, LiF:Mg,Si and LiF:Cu,Si with low concentrations of Mg and Cu were measured and were compared with those with high concentrations to investigate further the role of dopants in LiF:Mg,Cu,Si material. The shape of glow curves of the four samples is similar; however, LiF:Cu,Si sample had no Mg dopant. It is concluded that the TL emission to be from self-trapped excitons in LiF, and this emission could be enhanced and altered by Mg, Cu and Si dopants in LiF:Mg,Cu,Si; all three dopants are necessary to obtain the bright TL emission and may be involved in the luminescence process; Mg seems to be the most essential dopant and Cu is involved in the trapping although the role of Mg dominates; both Cu and Si play a role in the main emission process and Cu also plays a role in reducing the emission around 610 nm.