Luminescence properties and Judd-Ofelt analysis of Tb3+ doped Sr2YTaO6 double perovskite phosphors for white LED applications

A series of Tb3+-doped Sr2YTaO6 double perovskite phosphors (SYT:Tb3+) were synthesized using a conventional solid-state reaction method. A strong green emission was observed in the SYT:Tb3+ phosphors, and the optimal doping concentration of Tb3+ was confirmed to be 5 mol%. The electric dipole-dipole interaction was ascribed to be the main mechanism for the luminescence concentration quenching. Analysis of the concentration-dependent fluorescence decay confirmed that the self-generated quenching model holds for the dynamic process of Tb3+ decays in SYT. Furthermore, the internal quantum efficiencies, non-radiative transition rates, and energy transfer rates of the 5D4 level for the SYT:Tb3+ samples were estimated, respectively. The luminescence thermal stability of the sample was also evaluated based on the Arrhenius model. The chromaticity shift of the SYT:5 mol% Tb3+ phosphor was examined to be 0.013 when the sample temperature was increased from 303 to 483 K, thus indicating excellent chromaticity shifting resistance under high temperature conditions. Moreover, the Judd-Ofelt parameters were calculated from the emission spectra of SYT:Tb3+ to be Ω2 = 0.29 × 10-20, Ω4 = 0.45 × 10-20, and Ω6 = 0.72 × 10-20 cm2, respectively. The fluorescence branching ratios and radiative transition rates for the 5D4 level were calculated based on the obtained Judd-Ofelt parameters. Finally, a white light-emitting diode (LED) prototype was assembled using a 310 nm LED chip combined with a prepared green SYT:Tb3+ phosphor and two other commercial blue and red phosphors. The obtained warm white light exhibits good chromaticity coordinates (0.32, 0.32) and a high color rendering index of 96.1. Based on the above results, it can be known that the prepared SYT:Tb3+ phosphors have a potential application as green emitting phosphors in white LEDs.

Multicolor-emitting Er3+ and Er3+/Yb3+ doped Zn2GeO4 phosphors combining static and dynamic identifications for advanced anti-counterfeiting application

Anti-counterfeiting labels based on luminescence materials are a newly emerging technique for protecting legal goods and intellectual property. In the anti-counterfeiting field to prevent forgery and cloning, luminescence materials with properties different from the commercialized and traditional ones are in urgent need. In this work, multicolor-emitting Er3+ single-doped and Er3+/Yb3+ co-doped Zn2GeO4 phosphors combining static and dynamic identifications were developed in order to achieve advanced anti-counterfeiting application. The variation of trap content with increasing the doping content of rare earth ions was analyzed through X - ray photoelectron spectroscopy, thermoluminescence analysis. It was found that there are two types of traps with different depth in Zn2GeO4 phosphors. The depths of the traps were experimentally confirmed to be 0.68 and 0.79 eV, respectively. The transient photocurrent response measurement confirmed the existence of charge carriers, and the mechanism for long persistent luminescence was deduced. The multicolor upconversion mechanisms under 980 and 1550 nm excitation were also discovered. Based on the multicolor steady and transient emission features, an anti-counterfeiting pattern was designed using the phosphors. Static and dynamic identification was demonstrated and presented in detail. Finally, it is indicated that the studied phosphors are excellent candidates for potential applications in luminescence anti-counterfeiting labels.

Near infrared emissions from both high efficient quantum cutting (173%) and nearly-pure-color upconversion in NaY(WO4)2:Er3+/Yb3+ with thermal management capability for silicon-based solar cells

Raising photoelectric conversion efficiency and enhancing heat management are two critical concerns for silicon-based solar cells. In this work, efficient Yb3+ infrared emissions from both quantum cutting and upconversion were demonstrated by adjusting Er3+ and Yb3+ concentrations, and thermo-manage-applicable temperature sensing based on the luminescence intensity ratio of two super-low thermal quenching levels was discovered in an Er3+/Yb3+ co-doped tungstate system. The quantum cutting mechanism was clearly decrypted as a two-step energy transfer process from Er3+ to Yb3+. The two-step energy transfer efficiencies, the radiative and nonradiative transition rates of all interested 4 f levels of Er3+ in NaY(WO4)2 were confirmed in the framework of Föster-Dexter theory, Judd-Ofelt theory, and energy gap law, and based on these obtained efficiencies and rates the quantum cutting efficiency was furthermore determined to be as high as 173% in NaY(WO4)2: 5 mol% Er3+/50 mol% Yb3+ sample. Strong and nearly pure infrared upconversion emission of Yb3+ under 1550 nm excitation was achieved in Er3+/Yb3+ co-doped NaY(WO4)2 by adjusting Yb3+ doping concentrations. The Yb3+ induced infrared upconversion emission enhancement was attributed to the efficient energy transfer 4I11/2 (Er3+) + 2F7/2 (Yb3+) → 4I15/2 (Er3+) + 2F5/2 (Yb3+) and large nonradiative relaxation rate of 4I9/2. Analysis on the temperature sensing indicated that the NaY(WO4)2:Er3+/Yb3+ serves well the solar cells as thermos-managing material. Moreover, it was confirmed that the fluorescence thermal quenching of 2H11/2/4S3/2 was caused by the nonradiative relaxation of 4S3/2. All the obtained results suggest that NaY(WO4)2:Er3+/Yb3+ is an excellent material for silicon-based solar cells to improve photoelectric conversion efficiency and thermal management.

POS0788 CIRCULATING EXOSOMES PROMOTE LUPUS NEPHRITIS IN MRL-LPR MICE

Background:

Systemic Lupus Erythematosus (SLE) is a prototypic autoimmune disease that characterized by the loss of self-tolerance and the production of autoantibodies (autoAbs) [1, 2]. Lupus nephritis (LN), the severe organ-threatening manifestations of SLE, could cause massive damage to patients[3, 4]. Currently, some exosomal microRNAs (miRNAs) are considered as potential biomarkers in SLE. However, the role of exosomal miRNAs in Lupus Nephritis (LN) remains unclear.

Objectives:

The purpose of this study was to investigate molecular mechanism of plasma exosomal miRNAs in the development of Lupus Nephritis.

Methods:

Circulating exosomes were isolated from plasma of patients with LN, SLE without LN (NLN). Plasma exosomes were authenticated by Western Blot, Nanosight Tracking Analysis (NTA) and transmission electron microscopy (TEM). Fluorescence microscopy of co-cultured plasma exosomes and podocytes demonstrated that exosomes were uptaken into podocytes. Moreover, cell apoptosis and the inflammation factors was assessed using Western Blot. We analyzed the expression profiles of miRNAs in LN and NLN exosomes and the expression profiles of mRNAs of podocytes stimulated with LN and NLN exosomes with the help of next generation sequencing (NGS).

Results:

We demonstrate that exosomes derived from LN plasma could be taken by neighboring podocytes and promote the apoptosis of podocytes and the expression of inflammation factors. In addition, the sequencing found that miRNAs were differentially expressed in LN and NLN exosomes and mRNAs were differentially expressed in podocytes stimulated with LN and NLN exosomes.

Conclusion:

LN plasma exosomes have a potency to stimulate the apoptosis of podocytes and the expression of inflammation factors. Moreover, differentially expressed miRNAs in exosomes play a potential role in the development of LN.

References:

[1]T. Colasanti, A. Maselli, F. Conti, M. Sanchez, C. Alessandri, C. Barbati, D. Vacirca, A. Tinari, F. Chiarotti, A. Giovannetti, F. Franconi, G. Valesini, W. Malorni, M. Pierdominici, E. Ortona, Autoantibodies to estrogen receptor α interfere with T lymphocyte homeostasis and are associated with disease activity in systemic lupus erythematosus, Arthritis and rheumatism, 64 (2012) 778-787.

[2]H.A. Al-Shobaili, A.A. Al Robaee, A.A. Alzolibani, Z. Rasheed, Antibodies against 4-hydroxy-2-nonenal modified epitopes recognized chromatin and its oxidized forms: role of chromatin, oxidized forms of chromatin and 4-hydroxy-2-nonenal modified epitopes in the etiopathogenesis of SLE, Disease markers, 33 (2012) 19-34.

[3]A. Kaul, C. Gordon, M.K. Crow, Z. Touma, M.B. Urowitz, R. van Vollenhoven, G. Ruiz-Irastorza, G. Hughes, Systemic lupus erythematosus, Nat Rev Dis Primers, 2 (2016) 16039.

[4]M.G. Tektonidou, A. Dasgupta, M.M. Ward, Risk of End-Stage Renal Disease in Patients With Lupus Nephritis, 1971-2015: A Systematic Review and Bayesian Meta-Analysis, Arthritis & rheumatology (Hoboken, N.J.), 68 (2016) 1432-1441.

Disclosure of Interests:

None declared

Pharmacogenetics of a PARP inhibitor ABT-888 metabolic pathway

e14556

Background: Poly(ADP-ribose) polymerase (PARP) is essential for single-stranded DNA break repair and repair of DNA damage can lead to radio- and chemo-resistance. Thus, inhibition of PARP activity can sensitize cells to cytotoxic therapies. ABT-888 is a potent, orally bioavailable PARP inhibitor. Preclinical studies suggest that ABT-888 potentiates multiple cytotoxic agents and its efficacy is correlated with plasma/tumor drug concentrations. The objective of this study was to determine the pharmacogenetic effect of genetic variants in the ABT-888 metabolic pathway, with the aim to better understand molecular basis of the variation in ABT-888 pharmacokinetics (PK) and therapeutic outcome. Methods: The major enzymes responsible for ABT-888 metabolism were identified by in vitro metabolism studies with specific recombinant human cytochrome P450 (CYP) enzymes. The functional significance of genetic variants of the identified enzymes was assessed by examining ABT-888 metabolic kinetics by candidate variant enzymes and microsomes. The association of the functional significant genetic variants with the PK and clinical outcome is being evaluated in the context of an ongoing phase I trial in which ABT-888 is administered in combination with irinotecan in patients with advanced solid tumors. Results: ABT-888 was metabolized predominantly by human CYP2D6, to a less extent by CYP1A1, and to a negligible extent by CYP1A2, 2C9, 2C19, 3A4, and 3A5. CYP2D6*10 exhibited markedly reduced catalytic capability in ABT-888 overall metabolism and the metabolite (A-925088) formation, with in vitro maximum clearance being 31% and 5.3%, respectively, of that estimated from the wild-type CYP2D6. In human liver microsomes carrying homozygous CYP2D6*4, the rates of parent drug disappearance and metabolite formation were significantly lower than those observed in the microsomes carrying wild-type CYP2D6, P < 0.05. Conclusions: CYP2D6 is the predominant enzyme responsible for the hepatic metabolism of ABT-888. Common allelic variants CYP2D6*10 and *4 are associated with significantly reduced metabolic activity towards ABT-888. CYP2D6 polymorphisms may influence the PK and therapeutic outcome of ABT-888. Its clinical relevance remains to be determined.

No significant financial relationships to disclose.

Physiological responses during hypoglycaemia induced by regular human insulin or a novel human analogue, insulin glargine

AIM

Glargine, a product of recombinant technology, has different structural and physicochemical properties compared with native human insulin. We determined whether such differences are associated with alterations in the responses to hypoglycaemia induced by glargine.

METHODS

Nineteen adults (six healthy and 13 with type 1 diabetes) underwent a 5-h hyperinsulinaemic (2 mU/kg/min(-1)) stepped hypoglycaemic clamps (hourly targets of 4.7, 4.2, 3.6, 3.1 and 2.5 mmol/l, respectively) on two occasions using intravenous infusion of regular human insulin or glargine, in random sequence. Hypoglycaemic symptoms, counter-regulatory hormones and glucose disposal rates were assessed at intervals throughout the clamps. A 1-week 'wash out' period was observed between studies.

RESULTS

The peak total symptoms scores (mean +/- s.e.m.) at nadir blood glucose (2.5 mmol/1) were 18.83 +/- 2.68 (healthy) and 17.46 +/- 3.62 (diabetic) during regular insulin, and 18.50 +/- 3.20 (healthy) and 19.08 +/- 3.83 (diabetic) during glargine infusion. The peak epinephrine levels during hypoglycaemia were 767.8 +/- 140.4 pg/ml (regular insulin) and 608.8 +/- 129.9 pg/ml (glargine) among healthy subjects, and 332.5 +/- 54.8 pg/ml (regular insulin) and 321.8 +/- 67.4 pg/ml (glargine) in diabetic patients. Diabetic patients had blunted glucagon responses during hypoglycaemia with either insulin. Both insulins also elicited similar rates of glucose disposal.

CONCLUSIONS

We conclude that insulin glargine and regular human insulin elicit comparable symptomatic and counter-regulatory hormonal responses during hypoglycaemia in healthy or diabetic subjects, and induce similar rates of glucose disposal. Since glargine is designed for subcutaneous (s.c.) use, it is possible (though unlikely) that our findings obtained using an intravenous protocol could differ from responses to hypoglycaemia induced by the s.c. route.

Peroxisome proliferator-activated receptors: a family of lipid-activated transcription factors

Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear transcription factors that belong to the steroid receptor superfamily. This family of PPARs includes PPARalpha, PPARdelta, PPARgamma1, and PPARgamma2. These PPARs are related to the T3 and vitamin D(3) receptors and bind to a hexameric direct repeat as a heterodimeric complex with retinoid receptor Xalpha. PPARs regulate the expression of a wide array of genes that encode proteins involved in lipid metabolism, energy balance, eicosanoid signaling, cell differentiation, and tumorigenesis. A unique feature of these steroid-like receptors is that the physiologic ligands for PPARs appear to be fatty acids from the n-6 and n-3 families of fatty acids and their respective eicosanoid products. This review describes the characteristics, regulation, and gene targets for PPARs and relates their effects on gene expression to physiologic outcomes that affect lipid and glucose metabolism, thermogenesis, atherosclerosis, and cell differentiation.

Cytosolic and nuclear distribution of PPARgamma2 in differentiating 3T3-L1 preadipocytes

In light of the pivotal role that PPARgamma2 plays in the expression of fat specific genes (e.g., A-FABP), we have examined the hypothesis that a rise in PPARgamma2 protein is required for the expression of A-FABP, and that the acceleration of fat cell differentiation by the thiazolidinedione agent, pioglitazone (PIOG), reflects an increase in the abundance of PPARgamma2 mRNA and protein. Western analyses surprisingly revealed that undifferentiated 3T3-L1 fibroblasts contained significant levels of PPARgamma2 protein; that the amount of total cellular PPARgamma2 only increased 2-fold during differentiation; and that the levels of PPARgamma2 protein and mRNA were not increased by PIOG even though fat cell differentiation was accelerated by PIOG as revealed by a 20-fold increase in A-FABP expression. Cell fractionation studies revealed that PPARgamma2 was evenly distributed between the cytosolic and nuclear compartments in both undifferentiated and differentiating 3T3-L1 cells. Immunocytochemical studies with a PPARgamma2-specific antibody indicated that PPARgamma2 was diffusely distributed throughout the cytosol of undifferentiated 3T3-L1 cells, but as the differentiation progressed, the PPARgamma2 became focused around the developing lipid droplets. In contrast to PPARgamma2, undifferentiated 3T3-L1 cells contained no measurable quantities of RXRalpha, but once fat cell differentiation was initiated by treatment with IBMX and dexamethasone, the cellular content of RXRalpha increased several fold. The rise in RXRalpha content paralleled the induction of A-FABP, but the expression of RXRalpha was not enhanced by PIOG. Although the amount of PPARgamma2 and RXRalpha was unaffected by PIOG, gel shift assays revealed that PIOG stimulated PPARgamma2/RXRalpha binding to the adipose response element of A-FABP by 5-fold in less than 12 h. Apparently, RXRalpha rather than PPARgamma2 is the pivotal trans-factor essential for the initiation of terminal fat cell differentiation. However, the high cytsolic content of PPARgamma2 and its association with the lipid droplet of differentiating 3T3-L1 cells suggests PPARgamma2 may possess a cytosolic function in the developing fat cell.

A novel 3T3-L1 preadipocyte variant that expresses PPARgamma2 and RXRalpha but does not undergo differentiation

This report describes a novel adipocyte-like cell line termed 3T3-L1/RB1 that was derived from preadipocyte cell line, 3T3-L1. The 3T3-L1/RB1 cells continued to divide after reaching confluence, formed foci, and constitutively expressed a low level of adipose fatty acid binding protein (A-FABP) mRNA. However, 3T3L-1/RB cells did not undergo terminal differentiation as indicated by the failure of insulin and thiazolidendiones to induce the expression of A-FABP, lipoprotein lipase, and fatty acid synthase. We hypothesized that the 3T3-L1/RB1 variant did not respond to differentiation stimuli because it did not express either peroxisomal proliferator activated receptor gamma2 (PPARgamma2) or its heterodimer partner, retinoid X receptor alpha (RXRalpha). Surprisingly, Western blots revealed that 3T3-L1/ RB1 cells contained both PPARgamma2 and RXRalpha proteins at levels equal to or greater than that of the parent cell line. However, gel retardation assays using the adipose response element from A-FABP and nuclear protein extracts from 3T3-L1/RB1 cells treated with insulin or pioglitazone revealed that nuclear protein extracts from 3T3-L1/RB1 cells had very little ability to bind the PPARgamma2 recognition sequence of the A-FABP gene. These data suggest that the 3T3-L1/RB1 variant contains a mutation that may prevent ligand activation of PPARgamma2, and the subsequent conversion of 3T3-L1/RB1 cells to mature fat cells.

[Study of ozonization effects on mineral water components]

The disinfection effects of ozonization and its influences on chemical components of mineral water were investigated. The results showed that ozone at the level of 0.5 mg/L and with the exposure time of 5 minutes effectively destroyed bacteria in mineral water. High level ozone showed no strong influences on some beneficial components, such as strontium and metasilicate and on some main components, such as bicarbonate, hardness and alkalinity, but slightly elevated pH value. Ozonization reduced the contents of total dissolved solids and oxygen demand, and decomposed some reductive contaminants such as ammonia, cyanide and phenols. Ozonization will convert part of the bromide into hypobromite and bromate.

Penetration of levofloxacin into lung tissue after oral administration to subjects undergoing lung biopsy or lobectomy

STUDY OBJECTIVE

To evaluate the pulmonary tissue distribution of levofloxacin, the new once-daily fluoroquinolone, after a single 500-mg oral dose.

DESIGN

Open-label study.

SETTING

One pulmonary clinic and two university-affiliated teaching hospitals.

PATIENTS

Eighteen adults undergoing lung biopsy or lobectomy.

INTERVENTIONS

Levofloxacin plasma and lung tissue concentrations were determined by high-performance liquid chromatography with fluorescence detection. Lung tissue levofloxacin concentrations were corrected for blood contamination by measuring hemoglobin.

MEASUREMENTS AND MAIN RESULTS

After a single 500-mg oral dose, concentrations of levofloxacin in lung tissue consistently exceeded those in plasma at every time point over the 24-hour sampling period, with tissue:plasma penetration ratios of 2.02 (2-3 hrs), 5.02 (4-6 hrs), 5.13 (11-17 hrs), and 4.13 (22-25 hrs). The mean penetration ratio over the 24-hour sampling period was 3.95 (range 1.06-9.98). Lung tissue concentrations of levofloxacin also exceeded minimum inhibitory concentration values for most community-acquired respiratory tract pathogens over the 24 hours.

CONCLUSION

This study supports clinical evaluation of levofloxacin as once-daily oral therapy for community-acquired lower respiratory tract infections.

Identification and analysis of discrete functional domains in the pro region of pre-pro-transforming growth factor beta 1

A series of site-specific insertion and deletion mutants was prepared in the pro domain of transforming growth factor beta 1 (TGF beta 1) encoded by simian TGF beta 1 cDNA. These mutants were transiently expressed in COS-1 cells and the ability of each to be properly processed, folded correctly, and secreted was determined by immunoblot analysis of cells and culture supernatants. Insertions in regions corresponding to amino acid residues 50, 154, and 170 blocked secretion; culture supernatants from COS-1 cells showed no immunologically reactive proteins, whereas intact cells contained high levels of the mutant polypeptides. Insertions in the middle portion of the pro domain at residues 81, 85, and 144 affected disulfide maturation of the mature TGF beta 1. An insertion at residue 110, on the other hand, appeared to destabilize the mature TGF beta 1 polypeptide, resulting in degraded growth factor. Relatively small (10 amino acids) to large (125 amino acids) deletion mutations in the pro domain of TGF beta 1, when expressed as the full-length pre-pro-TGF beta 1, appeared to block secretion. By contrast, if the pro domain (designated beta 1-latency-associated peptide [beta 1-LAP]) was expressed independently, deletion mutants in the region 40-110 were readily secreted by the COS-1 cells, whereas deletions in residues 110-210 either destabilized the structure of the protein or blocked its intracellular transport. Cross-linking assays employing radioiodinated TGF beta 1 and biological assays indicate that residues 50-85 of beta 1-LAP are required for association with mature TGF beta 1.

Transforming growth factor beta 1: importance of glycosylation and acidic proteases for processing and secretion

The role of glycosylation of the transforming growth factor-beta 1 (TGF-beta 1) precursor was investigated by treating a transfected Chinese hamster ovary (CHO) cell line expressing high levels of recombinant TGF-beta 1 (TGF-beta 3-2000 cells) with a series of glycosylational inhibitors. Tunicamycin, a nucleoside antibiotic which prevents the formation of the dolichol intermediate necessary for oligosaccharide addition of the nascent polypeptide chain, appeared to block secretory exit and led to an increase in the cellular associated, nonglycosylated pro-TGF-beta 1 form. 1-Deoxymannojirimycin and swainsonine, inhibitors of the mannosidases I and II, respectively, blocked complete glycoprotein processing of the TGF-beta 1 precursor as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by sensitivity to glycosidases. However, the abnormal TGF-beta 1 polypeptides containing the altered carbohydrate side chains were secreted readily by the CHO cells. In contrast, inhibitors of the glucosidases at the first step in glycoprotein remodeling, 1-deoxynojirimycin and castanospermine, markedly inhibited secretion of the TGF-beta 1 polypeptides from transfected CHO cells. In all cases, these inhibitors did not appear to affect proteolytic processing of the TGF-beta 1 polypeptides. Furthermore, inhibitor treatment did not affect mannose-6-phosphorylation of the TGF-beta 1 polypeptides. These results suggest that glycosylation and early stage remodeling of oligosaccharide side chains are necessary for secretion of TGF-beta 1. Treatment of the transfected CHO cells with weak bases (NH4Cl and chloroquine), or a monovalent ionophore (monensin), prevented proteolytic processing of the TGF-beta 1 precursor indicating that cleavage occurs by proteases in an acidic cellular compartment.