Mesoporous TiO2 nanostructures: A route to minimize Pt loading on titania photocatalysts for hydrogen production

Mesostructured TiO2 nanocrystals have been prepared using Pluronic F127 as the structure-directing agent. Platinum nanoparticles at different contents (0.1-1.0 wt%) have been photochemically deposited onto the mesoporous TiO2. TEM investigation of 0.2 wt% Pt/TiO2 calcined at 450 °C reveals that the TiO2 particles are quite uniform in size and shape with the particle sizes of TiO2 and Pt being 10 and 3 nm, respectively. The photocatalytic activities of the Pt loaded TiO2 have been assessed and compared with those of nonporous commercial Pt/TiO2-P25 by determining the rates and the photonic efficiencies of molecular hydrogen production from aqueous methanol solutions. The results show that the amount of hydrogen evolved on Pt/TiO2-450 at low Pt loading (0.2 wt%) is three times higher than that evolved on Pt/TiO2-P25 and twelve times higher than that evolved on Pt/TiO 2-350. Despite the BET surface area of the TiO2-450 photocatalyst being 3.5 times higher than that of TiO2-P25, a 60% smaller amount of the Pt co-catalyst is required to obtain the optimum photocatalytic hydrogen production activity. The reduced Pt loading on the mesoporous TiO2 will be important both from a commercial and an ecological point of view. © 2011 the Owner Societies

Blumea balsamifera (L.) DC. elicit anti-kinase, anti-phosphatase and cytotoxic activities against acute promyelocytic leukemia cells (HL-60)

Blumea balsamfera (L.) DC. (B. balsamfera) extract has been shown to exhibit many biological activities. However, the anti-kinase, anti-phosphatase and cytotoxic activities of B. balsamfera are not well understood. Therefore, this study aimed to investigate the anti-kinase and antiphosphatase activities using MKK1, MSG5 and PP1 screening systems. Cytotoxic activity was evaluated using acute promyelocytic leukemia cell lines (HL-60). Methanol extracts of B. balsamfera were partitioned into hexane (HE), chloroform (CE), chloroform-methanol (CME), butanol (BE) and aqueous fractions (AQE). Only the CE fraction demonstrated toxic activity against PP1 screening system. Other fractions did not show activity in PP1 screening. CE fractions were further fractionated using silica gel chromatography and a further 11 fractions were obtained. Fraction 2 (CE.F2) showed activity against PP1 and was further fractionated and tested. CE.F2.F6.F3 fraction tested positive against PP1. Inhibition of PP1 by the F2.F6.F3 fraction was further confirmed using an enzymatic reaction and the Vmax and Km constants were 124.999 µmol/ml.min and 204.624 µM, respectively. A Lineweaver-Burk plot outcome of F2.F6.F3 revealed decreasing of Km and Vmax values which supported the inhibition of PP1 activities. Cytotoxic activities against HL-60 were observed for the CE, CE.F1, CE.F2 and CE.F7 fractions. We have demonstrated that B. balsamfera and its specific fractions exhibited anti-kinase and anti-phosphatase activities. These substances have the potential to be used as treatment agent for acute promyelocytic leukemia

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

MOLECULAR CLONING AND EXPRESSION OF AN OVINE CDNA ENCODING BOTH STEROID 11?-HYDROXYLASE AND ALDOSTERONE SYNTHASE ACTIVITES

Ph.DDOCTOR OF PHILOSOPH

Testosterone-induced adult neurosphere growth is mediated by sexually-dimorphic aromatase expression

We derived adult neural stem/progenitor cells (NSPCs) from the sub-ventricular zone of male and female mice to examine direct responses to principal sex hormones. In the presence of epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF2) NSPCs of both sexes expressed nestin and sox2, and could be maintained as neurospheres without addition of any sex hormones. The reverse was not observed; neither testosterone (T), 17β-estradiol (E(2)) nor progesterone (P(4)) was able to support neurosphere growth in the absence of EGF and FGF2. Ten nanomolar T, E(2) or P(4) induced nestin(+) cell proliferation within 20 min and enhanced neurosphere growth over 7 days irrespective of sex, which was abolished by Erk inhibition with 20 μM U0126. Maintaining neurospheres with each sex hormone did not affect subsequent neuronal differentiation. However, 10 nM T, E(2) or P(4) added during differentiation increased βIII tubulin(+) neuron production with E(2) being more potent compared to T and P(4) in both sexes. Androgen receptor (AR) inhibition with 20 μM flutamide but not aromatase inhibition with 10 μM letrozole reduced basal and T-induced neurosphere growth in females, while only concurrent inhibition of AR and aromatase produced the same effect in males. This sex-specific effect was supported by higher aromatase expression in male neurospheres compared to females measured by Western blot and green fluorescent protein (GFP) reporter. Ten micromolar menadione induced oxidative stress, impaired neurosphere growth and up-regulated aromatase expression in both sexes. However, under oxidative stress letrozole significantly exacerbated impaired neurosphere growth in males only. While both E(2) and T could prevent oxidative stress-induced growth reduction in both sexes, the effects of T were dependent on innate aromatase activity. We show for the first time that intrinsic androgen and estrogen signaling may impact the capacity of NSPCs to produce neural progenitors under pathological conditions of oxidative stress

Characterization of aromatase expression in the adult male and female mouse brain. I. Coexistence with oestrogen receptors a and ?, and androgen receptors

Aromatase catalyses the last step of oestrogen synthesis. There is growing evidence that local oestrogens influence many brain regions to modulate brain development and behaviour. We examined, by immunohistochemistry, the expression of aromatase in the adult male and female mouse brain, using mice in which enhanced green fluorescent protein (EGFP) is transcribed following the physiological activation of the Cyp19A1 gene. EGFP-immunoreactive processes were distributed in many brain regions, including the bed nucleus of the stria terminalis, olfactory tubercle, medial amygdaloid nucleus and medial preoptic area, with the densest distributions of EGFP-positive cell bodies in the bed nucleus and medial amygdala. Differences between male and female mice were apparent, with the density of EGFP-positive cell bodies and fibres being lower in some brain regions of female mice, including the bed nucleus and medial amygdala. EGFP-positive cell bodies in the bed nucleus, lateral septum, medial amygdala and hypothalamus co-expressed oestrogen receptor (ER) α and β, or the androgen receptor (AR), although single-labelled EGFP-positive cells were also identified. Additionally, single-labelled ERα−, ERβ- or AR-positive cell bodies often appeared to be surrounded by EGFP-immunoreactive nerve fibres/terminals. The widespread distribution of EGFP-positive cell bodies and fibres suggests that aromatase signalling is common in the mouse brain, and that locally synthesised brain oestrogens could mediate biological effects by activating pre- and post-synaptic oestrogen α and β receptors, and androgen receptors. The higher number of EGFP-positive cells in male mice may indicate that the autocrine and paracrine effects of oestrogens are more prominent in males than females

Increasing cDNA yields from single-cell quantities of mRNA in standard laboratory reverse transcriptase reactions using acoustic microstreaming

Correlating gene expression with cell behavior is ideally done at the single-cell level. However, this is not easily achieved because the small amount of labile mRNA present in a single cell (1-5% of 1-50pg total RNA, or 0.01-2.5pg mRNA, per cell) mostly degrades before it can be reverse transcribed into a stable cDNA copy. For example, using standard laboratory reagents and hardware, only a small number of genes can be qualitatively assessed per cell. One way to increase the efficiency of standard laboratory reverse transcriptase (RT) reactions (i.e. standard reagents in microliter volumes) comprising single-cell amounts of mRNA would be to more rapidly mix the reagents so the mRNA can be converted to cDNA before it degrades. However this is not trivial because at microliter scales liquid flow is laminar, i.e. currently available methods of mixing (i.e. shaking, vortexing and trituration) fail to produce sufficient chaotic motion to effectively mix reagents. To solve this problem, micro-scale mixing techniques have to be used. A number of microfluidic-based mixing technologies have been developed which successfully increase RT reaction yields. However, microfluidics technologies require specialized hardware that is relatively expensive and not yet widely available. A cheaper, more convenient solution is desirable. The main objective of this study is to demonstrate how application of a novel 'micromixing' technique to standard laboratory RT reactions comprising single-cell quantities of mRNA significantly increases their cDNA yields. We find cDNA yields increase by approximately 10-100-fold, which enables: (1) greater numbers of genes to be analyzed per cell; (2) more quantitative analysis of gene expression; and (3) better detection of low-abundance genes in single cells. The micromixing is based on acoustic microstreaming, a phenomenon where sound waves propagating around a small obstacle create a mean flow near the obstacle. We have developed an acoustic microstreaming-based device ('micromixer') with a key simplification; acoustic microstreaming can be achieved at audio frequencies by ensuring the system has a liquid-air interface with a small radius of curvature. The meniscus of a microliter volume of solution in a tube provides an appropriately small radius of curvature. The use of audio frequencies means that the hardware can be inexpensive and versatile, and nucleic acids and other biochemical reagents are not damaged like they can be with standard laboratory sonicators