Identification of CD14 transcript in blood polymorphonuclear neutrophil leukocytes and functional variation in Holsteins

Polymorphonuclear neutrophil (PMN) leukocytes are primary phagocytic cells of the bovine mammary gland and a first line of defense against invading pathogens during bovine mastitis infection. Cluster of differentiation 14 (CD14) is mainly expressed in macrophages and neutrophils and acts as a co-receptor that binds bacterial lipopolysaccharide (LPS) and recruits PMNs to CD14-LPS complexes in mammary epithelial cells. In this study, we identified a novel splice variant in PMNs, named CD14-SV, characterized by a deleted region from c.143-579 nt compared to the CD14 reference mRNA sequence. Moreover, a single nucleotide polymorphism (c.523 A>G) in exon 2 of CD14 was identified and found to modify the secondary structure and hydrophilicity of the CD14 protein. Association analysis also showed that the milk somatic cell score, an indicator of mastitis, of cows with the GG genotype was lower than that of cows with the AA and AG genotypes. Our findings suggest that the expression of CD14 in bovine blood PMNs is regulated by alternative splicing, and that CD14-SV is a candidate functional marker that may influence mastitis-resistance in dairy cows.

Effects and mechanism of Tripterygium wilfordii on chronic glomerulo nephritis

The objective of this study was to investigate the clinical effects of Tripterygium wilfordii on chronic glomerulo nephritis (CGN) and its mechanisms. Eighty-two cases of CGN treated in our hospital were randomly divided into observation and control groups. The control group was treated with conventional western medicine, and the observation group was treated with conventional western medicine and orally-administered T. wilfordii pills for three courses of treatment, each consisting of 4 weeks. Changes in serum reatinine, blood urea nitrogen, blood total cholesterol, blood albumin, and 24-h urine protein were observed. The levels of peripheral tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were determined with enzyme-linked immunosorbent assay. The curative effects of both groups were evaluated respectively. Both groups had significantly improved serum creatinine, blood urea nitrogen, blood total cholesterol, blood albumin, and 24-h urine protein (P < 0.05), and the observation group exhibited a more significant improvement (P < 0.05). TNF-α and IL-6 levels in both groups obviously decreased (P < 0.05), and the observation group exhibited remarkable changes (P < 0.05). After treatment, the total efficiency of the observation group was 90.24%, which was significantly higher than the 73.17% of the control group (P < 0.05). In conclusion, T. wilfordii can significantly improve kidney function and clinical symptoms in CGN patients, and the mechanism is possibly related to its inhibition of the secretion of TNF-α and IL-6.

Stevens-Johnson syndrome and toxic epidermal necrolysis in patients with malignancies

BACKGROUND

Malignancy is known to be associated with an increased mortality rate in patients with Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). However, risk factors contributing to the poor prognosis of patients with SJS/TEN with malignancies remain undefined.

OBJECTIVES

To explore the potential involvement of malignancy and its related factors contributing to the poor outcome of SJS/TEN, in a retrospective study.

METHODS

In total 517 patients with SJS/TEN were enrolled. Forty-seven who sustained various types of malignancies were analysed for numerous malignancy-related factors, including cancer types, clinical stages and chemotherapies given or not before the onset of SJS/TEN.

RESULTS

We found that the mortality rate of patients with SJS/TEN with malignancies was higher than that of patients without malignancies (32%, 15/47 vs. 8·5%, 40/470, respectively) (P < 0·001). The use of phenytoin was significantly higher in the malignancy group. The presence of hepatocellular carcinoma (80%, four of five; P < 0·001; odds ratio 43) and colorectal cancer (67%, two of three; P = 0·022; odds ratio 21·5) significantly increased the death rate of patients with SJS/TEN, whereas lung cancer and urothelial carcinoma did not. Patients who had received ongoing or recent chemotherapy showed higher mortality than those without chemotherapy (P = 0·022; odds ratio 4·95). Furthermore, among the 47 patients with SJS/TEN with malignancies, lower serum albumin, haemoglobin and platelet count were detected in the deceased patients than in the surviving patients before the onset of SJS/TEN.

CONCLUSIONS

Our results suggest that several factors related to malignancies, such as specific cancer types, chemotherapy and malnutrition, may contribute to poor prognosis in patients with malignancies developing SJS/TEN.

Cleavage of Dicer protein by I7 protease during vaccinia virus infection

Dicer is the key component in the miRNA pathway. Degradation of Dicer protein is facilitated during vaccinia virus (VV) infection. A C-terminal cleaved product of Dicer protein was detected in the presence of MG132 during VV infection. Thus, it is possible that Dicer protein is cleaved by a viral protease followed by proteasome degradation of the cleaved product. There is a potential I7 protease cleavage site in the C-terminus of Dicer protein. Indeed, reduction of Dicer protein was detected when Dicer was co-expressed with I7 protease but not with an I7 protease mutant protein lack of the protease activity. Mutation of the potential I7 cleavage site in the C-terminus of Dicer protein resisted its degradation during VV infection. Furthermore, Dicer protein was reduced dramatically by recombinant VV vI7Li after the induction of I7 protease. If VV could facilitate the degradation of Dicer protein, the process of miRNA should be affected by VV infection. Indeed, accumulation of precursor miR122 was detected after VV infection or I7 protease expression. Reduction of miR122 would result in the suppression of HCV sub-genomic RNA replication, and, in turn, the amount of viral proteins. As expected, significant reduction of HCVNS5A protein was detected after VV infection and I7 protease expression. Therefore, our results suggest that VV could cleave Dicer protein through I7 protease to facilitate Dicer degradation, and in turn, suppress the processing of miRNAs. Effect of Dicer protein on VV replication was also studied. Exogenous expression of Dicer protein suppresses VV replication slightly while knockdown of Dicer protein does not affect VV replication significantly.

Phase I study of nanoliposomal irinotecan (PEP02) in advanced solid tumor patients

Purpose

To define the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and pharmacokinetics (PK) of PEP02, a novel liposome-encapsulated irinotecan, in patients with advanced refractory solid tumors.

Methods

Patients were enrolled in cohorts of one to three to receive escalating dose of PEP02 in a phase I trial. PEP02, from 60 to 180 mg/m², was given as a 90-min intravenous infusion, every 3 weeks.

Results

A total of 11 patients were enrolled into three dose levels: 60 (one patient), 120 (six patients) and 180 mg/m² (four patients). DLT was observed in three patients, one at 120 mg/m² (grade 3 catheter-related infection) and two at 180 mg/m² (grade 4 neutropenia lasting for >3 days in one, grade 4 hematological toxicities and grade 4 diarrhea in the other). MTD was determined as 120 mg/m². Comparing with those after free-form irinotecan in the literature, the dose-normalized PK of SN-38 (the active metabolite) after PEP02 was characterized by lower C_max, prolonged terminal half-life and higher AUC but with significant inter-individual variation. One patient who died of treatment-related toxicity had significantly higher C_max and AUC levels of SN-38 than those of the other three patients at 180 mg/m². Post hoc pharmacogenetic study showed that the patient had a combined heterozygosity genotype of UGT1A1*6/*28. Two patients had objective tumor response.

Conclusions

PEP02 apparently modified the PK parameters of irinotecan and SN-38 by liposome encapsulation. The MTD of PEP02 monotherapy at 3-week interval is 120 mg/m², which will be the recommended dose for future studies.

An addressable quantum dot qubit with fault-tolerant control-fidelity

Exciting progress towards spin-based quantum computing has recently been made with qubits realized using nitrogen-vacancy centres in diamond and phosphorus atoms in silicon. For example, long coherence times were made possible by the presence of spin-free isotopes of carbon and silicon. However, despite promising single-atom nanotechnologies, there remain substantial challenges in coupling such qubits and addressing them individually. Conversely, lithographically defined quantum dots have an exchange coupling that can be precisely engineered, but strong coupling to noise has severely limited their dephasing times and control fidelities. Here, we combine the best aspects of both spin qubit schemes and demonstrate a gate-addressable quantum dot qubit in isotopically engineered silicon with a control fidelity of 99.6%, obtained via Clifford-based randomized benchmarking and consistent with that required for fault-tolerant quantum computing. This qubit has dephasing time T2* = 120 μs and coherence time T2 = 28 ms, both orders of magnitude larger than in other types of semiconductor qubit. By gate-voltage-tuning the electron g*-factor we can Stark shift the electron spin resonance frequency by more than 3,000 times the 2.4 kHz electron spin resonance linewidth, providing a direct route to large-scale arrays of addressable high-fidelity qubits that are compatible with existing manufacturing technologies.

Production and pathogenicity of hepatitis C virus core gene products

Hepatitis C virus (HCV) is a major cause of chronic liver diseases, including steatosis, cirrhosis and hepatocellular carcinoma, and its infection is also associated with insulin resistance and type 2 diabetes mellitus. HCV, belonging to the Flaviviridae family, is a small enveloped virus whose positive-stranded RNA genome encoding a polyprotein. The HCV core protein is cleaved first at residue 191 by the host signal peptidase and further cleaved by the host signal peptide peptidase at about residue 177 to generate the mature core protein (a.a. 1-177) and the cleaved peptide (a.a. 178-191). Core protein could induce insulin resistance, steatosis and even hepatocellular carcinoma through various mechanisms. The peptide (a.a. 178-191) may play a role in the immune response. The polymorphism of this peptide is associated with the cellular lipid drop accumulation, contributing to steatosis development. In addition to the conventional open reading frame (ORF), in the +1 frame, an ORF overlaps with the core protein-coding sequence and encodes the alternative reading frame proteins (ARFP or core+1). ARFP/core+1/F protein could enhance hepatocyte growth and may regulate iron metabolism. In this review, we briefly summarized the current knowledge regarding the production of different core gene products and their roles in viral pathogenesis.

Identification of a locus characteristic of male individuals of buffalo grass [Buchloe dactyloides (Nutt.) Engelm.] by using an RAPD marker

Buffalo grass [Buchloe dactyloides (Nutt.) Engelm.] plants can be either male, female, or hermaphrodite (monoecious). As there is no morphological difference in the early vegetative growth of these three classes of plants, it is worthwhile to use molecular biological methods to attempt to identify the sex of a plant at this early growth period. In this study, we identified 23 plants that had a stable sex for over at least 3 years. Of these, 9 were male plants, 10 were female plants, and 4 were hermaphrodites. Screening of 300 RAPD primers identified a primer, namely S211 (5'-ttccccgcga-3'), which is capable of identifying male plants. The specific fragment was cloned, sequenced, and submitted to the GenBank database (accession No. JN982469). When used to identify the sex of 188 plants during their first growing season, the S211 primer correctly identified 85.8% of all male plants. Our results showed that the S211 primer can identify the male, and in doing so, it facilitates buffalo grass breeding work.

Surveillance of avian influenza A(H7N9) virus infection in humans and detection of the first imported human case in Taiwan, 3 April to 10 May 2013

On 3 April 2013, suspected and confirmed cases of influenza A(H7N9) virus infection became notifiable in the primary care sector in Taiwan, and detection of the virus became part of the surveillance of severe community-acquired pneumonia. On 24 April, the first imported case, reported through both surveillance systems, was confirmed in a man returning from China by sequencing from endotracheal aspirates after two negative throat swabs. Three of 139 contacts were ill and tested influenza A(H7N9)-negative.

Surveillance of avian influenza A(H7N9) virus infection in humans and detection of the first imported human case in Taiwan, 3 April to 10 May 2013

On 3 April 2013, suspected and confirmed cases of influenza A(H7N9) virus infection became notifiable in the primary care sector in Taiwan, and detection of the virus became part of the surveillance of severe community-acquired pneumonia. On 24 April, the first imported case, reported through both surveillance systems, was confirmed in a man returning from China by sequencing from endotracheal aspirates after two negative throat swabs. Three of 139 contacts were ill and tested influenza A(H7N9)-negative.

Both core and F proteins of hepatitis C virus could enhance cell proliferation in transgenic mice

The role of the protein encoded by the alternative open reading frame (ARF/F/core+1) of the Hepatitis C virus (HCV) genome in viral pathogenesis remains unknown. The different forms of ARF/F/core+1 protein were labile in cultured cells, a myc-tag fused at the N-terminus of the F protein made it more stable. To determine the role of core and F proteins in HCV pathogenesis, transgenic mice with either protein expression under the control of Albumin promoter were generated. Expression of core protein and F protein with myc tag (myc-F) could be detected by Western blotting analysis in the livers of these mice. The ratio of liver to body weight is increased for both core and myc-F transgenic mice compared to that of wild type mice. Indeed, the proliferating cell nuclear antigen protein, a proliferation marker, was up-regulated in the transgenic mice with core or myc-F protein. Further analyses by microarray and Western blotting suggested that β-catenin signaling pathway was activated by either core or myc-F protein in the transgenic mice. These transgenic mice were further treated with either Diethynitrosamine (a tumor initiator) or Phenobarbital (a tumor promoter). Phenobarbital but not Diethynitrosamine treatment could increase the liver/body weight ratio of these mice. However, no tumor formation was observed in these mice. In conclusion, HCV core and myc-F proteins could induce hepatocyte proliferation in the transgenic mice possibly through β-catenin signaling pathway.

Hepatitis B virus X gene differentially modulates cell cycle progression and apoptotic protein expression in hepatocyte versus hepatoma cell lines

The hepatitis B virus (HBV) X gene, which encodes the hepatitis B virus x protein (HBx), is essential for viral infection and genome replication, virus-associated liver disease, and development of hepatocellular carcinoma. However, the exact role(s) of HBx remain controversial. In this study, we focus on studying the role of HBx in the regulation of cell cycle and apoptosis in normal liver and hepatoma cell lines. We established the Huh7-X and Chang-X cell lines that constitutively express HBx. There were differences between the two cell lines in terms of cell cycle regulation and expression of p27 and transforming growth factor-β. Expression of HBx proteins dramatically increases expression of Bcl-2 and reduces levels of cleaved PARP protein in Chang-X cells, and it inhibits apoptosis under unfavourable conditions, such as serum starvation, in both cell lines. Our findings provide clues about the intracellular roles of HBx and demonstrate that expression of this protein is important for multiple cellular processes, that is, cell cycle progression and apoptosis, in hepatoma cells and normal liver cell lines.

Randomised clinical trial: a comparative study of 10-day sequential therapy with 7-day standard triple therapy for Helicobacter pylori infection in naïve patients

BACKGROUND

The eradication rates following standard triple therapy for Helicobacter pylori infection are declining worldwide. Recent studies have shown that sequential therapy for H. pylori infection yields high cure rates.

AIM

To compare the efficacy and tolerability of a sequential regimen as first-line treatment of H. pylori infection with a standard triple regimen.

METHODS

A total of 348 naïve H. pylori-infected patients from six hospitals in Korea were assigned randomly to standard triple or sequential therapy groups. Standard triple therapy consisted of 20 mg of rabeprazole, 1 g of amoxicillin and 500 mg of clarithromycin, twice daily for 7 days. Sequential therapy consisted of a 5-day dual therapy (20 mg of rabeprazole and 1 g of amoxicillin, twice daily) followed by a 5-day triple therapy (20 mg of rabeprazole, 500 mg of clarithromycin, and 500 mg of metronidazole, twice daily).

RESULTS

The intention-to-treat (ITT) and per-protocol (PP) eradication rates were 62.2% (95% CI 54.8-69.6%) and 76.0% (95% CI 68.5-83.5%) in the standard triple group, and 77.8% (95% CI 71.4-84.2%) and 87.9% (95% CI 82.3-93.5%) in the sequential group, respectively. The eradication rate was significantly higher in the sequential group compared with the standard triple group in both the ITT and PP populations (P = 0.002 and P = 0.013 respectively), whereas the incidence of adverse events was similar.

CONCLUSIONS

Ten-day sequential therapy is more effective and equally tolerated for eradication of H. pylori infection compared with standard triple therapy. Sequential therapy may have a role as first-line treatment for H. pylori infection.

Randomised clinical trial: a comparative study of 10-day sequential therapy with 7-day standard triple therapy for Helicobacter pylori infection in naïve patients

BACKGROUND

The eradication rates following standard triple therapy for Helicobacter pylori infection are declining worldwide. Recent studies have shown that sequential therapy for H. pylori infection yields high cure rates.

AIM

To compare the efficacy and tolerability of a sequential regimen as first-line treatment of H. pylori infection with a standard triple regimen.

METHODS

A total of 348 naïve H. pylori-infected patients from six hospitals in Korea were assigned randomly to standard triple or sequential therapy groups. Standard triple therapy consisted of 20 mg of rabeprazole, 1 g of amoxicillin and 500 mg of clarithromycin, twice daily for 7 days. Sequential therapy consisted of a 5-day dual therapy (20 mg of rabeprazole and 1 g of amoxicillin, twice daily) followed by a 5-day triple therapy (20 mg of rabeprazole, 500 mg of clarithromycin, and 500 mg of metronidazole, twice daily).

RESULTS

The intention-to-treat (ITT) and per-protocol (PP) eradication rates were 62.2% (95% CI 54.8-69.6%) and 76.0% (95% CI 68.5-83.5%) in the standard triple group, and 77.8% (95% CI 71.4-84.2%) and 87.9% (95% CI 82.3-93.5%) in the sequential group, respectively. The eradication rate was significantly higher in the sequential group compared with the standard triple group in both the ITT and PP populations (P = 0.002 and P = 0.013 respectively), whereas the incidence of adverse events was similar.

CONCLUSIONS

Ten-day sequential therapy is more effective and equally tolerated for eradication of H. pylori infection compared with standard triple therapy. Sequential therapy may have a role as first-line treatment for H. pylori infection.

Gastrodia Elata Bl Attenuates Cocaine-Induced Conditioned Place Preference and Convulsion, but not Behavioral Sensitization in Mice: Importance of GABA(A) Receptors

It has been suggested that GABAergic neurotransmission can modulate cocaine dependence and seizure activity. Since Gastrodia elata Bl (GE), an oriental herb agent, has been shown to enhance GABAergic transmission, we examined whether GE affects cocaine-induced seizures, conditioned place preference (CPP), and behavioral sensitization in mice. Treatment with GE (500 or 1000 mg/kg, p.o.) significantly delayed seizure onset time and significantly shortened seizure duration induced by cocaine (90 mg/kg, i.p.). In addition, cocaine (15 mg/kg, i.p.)-induced CPP was significantly attenuated by GE in a dose-dependent manner. However, GE did not significantly alter behavioral sensitization induced by cocaine (15 mg/kg, i.p.). In order to understand whether GABAergic receptors are implicated in GE-mediated pharmacological action in response to cocaine, GABA_A receptor antagonist bicuculline and GABA_B receptor antagonist SCH 50911 were employed in the present study. GE-mediated attenuations on the cocaine-induced seizures and CPP were significantly reversed by bicuculline (0.25 or 0.5 mg/kg, i.p.), but not by SCH 50911 (1.5 or 3.0 mg/kg, i.p.). Therefore, our results suggest that GE attenuates cocaine-induced seizures and CPP via, at least in part, GABA_A receptor activation.

Liquiritigenin decreases selective molecular and behavioral effects of cocaine in rodents

Cocaine, as an indirect dopamine agonist, induces selective behavioral and physiological events such as hyperlocomotion and dopamine release. These changes are considered as consequences of cocaine-induced molecular adaptation such as CREB and c-Fos. Recently, methanolic extracts from licorice was reported to decrease cocaine-induced dopamine release and c-Fos expression in the nucleus accumbens. In the present study, we investigated the effects of liquiritigenin (LQ), a main compound of licorice, on acute cocaine-induced behavioral and molecular changes in rats. LQ attenuated acute cocaine-induced hyperlocomotion in dose-dependent manner. In addition, LQ inhibited CREB phosphorylation and c-Fos expression in the striatum and the nucleus accumbens induced by acute cocaine. Results provide strong evidence that LQ effectively attenuates the acute behavioral effects of cocaine exposure and prevents the induction of selective neuroadaptive changes in dopaminergic signaling pathways. Further investigation of LQ from licorice extract might provide a novel therapeutic strategy for the treatment of cocaine addiction.

Spin filling of valley-orbit states in a silicon quantum dot

We report the demonstration of a low-disorder silicon metal-oxide-semiconductor (Si MOS) quantum dot containing a tunable number of electrons from zero to N = 27. The observed evolution of addition energies with parallel magnetic field reveals the spin filling of electrons into valley-orbit states. We find a splitting of 0.10 meV between the ground and first excited states, consistent with theory and placing a lower bound on the valley splitting. Our results provide optimism for the realisation in the near future of spin qubits based on silicon quantum dots.

Population dose from medical diagnostic exposure in Taiwan

Medical exposure showed a continuous increasing trend. This trend was due to the growth of diagnostic procedures such as computed tomography (CT) and interventional fluoroscopy (IVF). In the present work, results of a recent study on medical exposure in Taiwan are reported. This study analysed data from the National Health Insurance Research Database. Surveyed data on the dose indices, including the entrance surface dose in radiography, dose area product in fluoroscopy, CT dose index in CT and mean glandular dose in mammography, were applied. Using programmes and databases, dose indices were converted to the effective dose. For the year 2008, individual effective doses in Taiwan were estimated as 0.16, 0.37, 0.12 and 0.12 mSv for conventional radiography and fluoroscopy, CT, IVF and nuclear medicine, respectively. The total collective effective dose and the effective dose per individual for medical exposure were 17 788 person-Sv and 0.77 mSv, respectively.

Enterovirus type 71 2A protease functions as a transcriptional activator in yeast

Enterovirus type 71 (EV71) 2A protease exhibited strong transcriptional activity in yeast cells. The transcriptional activity of 2A protease was independent of its protease activity. EV71 2A protease retained its transcriptional activity after truncation of 40 amino acids at the N-terminus but lost this activity after truncation of 60 amino acids at the N-terminus or deletion of 20 amino acids at the C-terminus. Thus, the acidic domain at the C-terminus of this protein is essential for its transcriptional activity. Indeed, deletion of amino acids from 146 to 149 (EAME) in this acidic domain lost the transcriptional activity of EV71 2A protein though still retained its protease activity. EV71 2A protease was detected both in the cytoplasm and nucleus using confocal microscopy analysis. Coxsackie virus B3 2A protease also exhibited transcriptional activity in yeast cells. As expected, an acidic domain in the C-terminus of Coxsackie virus B3 2A protease was also identified. Truncation of this acidic domain resulted in the loss of transcriptional activity. Interestingly, this acidic region of poliovirus 2A protease is critical for viral RNA replication. The transcriptional activity of the EV71 or Coxsackie virus B3 2A protease should play a role in viral replication and/or pathogenesis.

Mutations Affecting Hyphal Colonization and Pyoverdine Production in Pseudomonads Antagonistic toward Phytophthora parasitica

In previous studies, Pseudomonas putida 06909 and Pseudomonas fluorescens 09906 suppressed populations of Phytophthora parasitica in the citrus rhizosphere, suggesting that these bacteria may be useful in biological control of citrus root rot. In this study we investigated the mechanisms of antagonism between the bacteria and the fungus. Both bacteria colonized Phytophthora hyphae and inhibited the fungus on agar media. A hyphal column assay was developed to measure the colonization of bacteria on fungal hyphae and to enrich for colonization-deficient mutants. In this way we identified Tn5 mutants of each pseudomonad that were not able to colonize the hyphae and inhibit fungal growth in vitro. Colonization-deficient mutants were nonmotile and lacked flagella. Survival of nonmotile mutants in a citrus soil was similar to survival of a random Tn5 mutant over a 52-day period. Additional screening of random Tn5 mutants of both pseudomonads for loss of fungal inhibition in vitro yielded two distinct types of mutants. Mutants of the first type were deficient in production of pyoverdines and in inhibition of the fungus in vitro, although they still colonized fungal hyphae. Mutants of the second type lacked flagella and were not able to colonize the hyphae or inhibit fungal growth. No role was found for antibiotic production by the two bacteria in the inhibition of the fungus. Our results suggest that both hyphal colonization and pyoverdine production are important in the inhibition of Phytophthora parasitica by P. fluorescens and P. putida in vitro.

Comparative investigation on structure and luminescence properties of fluoride phosphors codoped with Er3+/Yb3+

This paper reports on comparative investigation of structure and luminescence properties of tetragonal LiYF(4) and BaYF(5), and hexagonal NaYF(4) phosphors codoped with Er(3+)/Yb(3+) by a facile hydrothermal synthesis. The products were characterized by X-ray diffractometer, scanning electron microscope, and photoluminescence spectroscopy. Intense visible emissions centered at around 525, 550 and 650 nm, originated from the transitions of (2)H(11/2) --> (4)I(15/2), (4)S(3/2) --> (4)I(15/2), and (4)F(9/2) --> (4)I(15/2) of Er(3+), respectively, have been observed in all the samples upon excitation with a 980 nm laser diode, and the involved mechanisms have been explained. Based on the green up-conversion emission performance, the Yb(3+) concentrations of Er(3+)/Yb(3+)-codoped LiYF(4), BaYF(5), and NaYF(4) phosphors have been optimized to be 10, 20, and 20 mol*%, respectively. The quadratic dependence of fluorescence on excitation laser power has confirmed that two-photon contribute to up-conversion of the green-red emissions.

Melatonin inhibits arsenite-induced peripheral neurotoxicity

In this study, the effect of melatonin on sodium arsenite (arsenite)-induced peripheral neurotoxicity was investigated using dorsal root ganglion (DRG) explants. After 24-hr incubation, arsenite (30 microm) consistently elevated the expression of heat shock protein 70 and haeme oxygenase-1, two well-known stress proteins, in the treated DRG explants. Co-incubation with melatonin (4 and 20 mm) concentration-dependently attenuated arsenite-induced elevation in stress proteins. Furthermore, melatonin inhibited arsenite-induced phosphorylation of p38 and DNA fragmentation. Inhibition by melatonin of arsenite-induced apoptosis was mediated via inactivating both endoplasmic reticulum (ER) and mitochondrial pathways. In the ER pathway, melatonin suppressed arsenite-induced elevation in activating transcription factor-6 and CCAAT/enhancer-binding protein homologous protein in the nuclear fraction of the treated DRG explants. Moreover, melatonin attenuated arsenite-induced activation of caspase 12, an ER-specific enzyme. In the mitochondrial pathway, arsenite-induced increases in Bcl-2 levels and cytosolic cytochrome c were reduced by melatonin. At the same time, melatonin inhibited arsenite-induced activation of caspase 3 in the treated DRG explants. Compared with glutathione and N-acetyl cysteine, melatonin was more potent than either in inhibiting arsenite-induced elevation in stress proteins. Taken together, our study demonstrates that melatonin is protective against arsenite-induced neurotoxicity in DRG explants. In addition, melatonin prevented arsenite-induced apoptosis via suppression of ER and mitochondrial activation. Our data suggest that melatonin is potentially a therapy for arsenite-induced peripheral neuropathy.

Electron emissions in InAs quantum dots containing a nitrogen incorporation induced defect state: the influence of thermal annealing

With the incorporation of nitrogen (N) into InAs quantum dots (QDs), the carrier distribution near the QD displays electron emissions from a localized N-induced defect state at 0.34 eV and a weak emission at 0.15 eV from the QD. This defect state causes drastic carrier depletion in the neighboring GaAs bottom layer near the QD, which can effectively suppress tunneling emission for the QD excited states. As a result, electrons escape from the QD ground state through thermal emission to near the GaAs conduction band, rather than through thermal emission to the QD first excited state and a subsequent tunneling to the GaAs conduction band, as observed in InAs QDs without N incorporation. Thermal annealing can weaken the defect emission and enhance the QD emission, suggesting a removal of the defect state and a recovery of carriers in the QD. Increasing annealing temperature can significantly decrease the emission time and energy of the QD emission, which is explained by a weakening of tunneling suppression due to the removal of the defect state.