Absolute photoionization cross section measurements of the Kr I-isoelectronic sequence

Photoionization spectra have been recorded in the 4s, 4p and 3d resonance regions for the Kr Iisoelectronic sequence using both the dual laser produced plasma technique (at DCU) to produce photoabsorption spectra, and the merged ion beam and synchrotron radiation technique (at ASTRID) to measure absolute photoionization cross sections. Profile parameters are compared for the 4s − np resonances of Rb+ and Sr2+. Many new 4p " ns, md transitions are identified with the aid of Hartree-Fock calculations, and consistent quantum defects are observed for the various ns and md Rydberg series. Absolute single and double photoionization cross sections recorded in the 3d region for Rb+ and Sr2+ ions show preferential decay via double photoionization. This is only the second report where both the DLP technique and the merged beam technique have been used simultaneously to record photoionization spectra, and the advantages of both techniques (i.e. better resolution in the case of DLP and values for absolute photoionization cross sections in the case of the merged beam technique) are highlighted

Season and vitamin D status are independently associated with glucose homeostasis in pregnancy

Background: Vitamin D status and season are intrinsically linked, and both have been proposed to be associated with glucose homeostasis in pregnancy, with conflicting results. We aimed to determine if exposure to winter and low maternal 25 hydroxyvitamin D (25OHD) in early pregnancy were associated with maternal glucose metabolism.Methods: This is a secondary data analysis of 334 pregnant women enrolled in the ROLO study, Dublin. Serum 25OHD, fasting glucose, insulin and insulin resistance (HOMA-IR) were measured in early (12 weeks' gestation) and late pregnancy (28 weeks' gestation). Season of first antenatal visit was categorised as extended winter (November–April) or extended summer (May–October). Multiple linear regression models, adjusted for confounders, were used for analysis.Results: Those who attended their first antenatal visit in extended winter had lower 25OHD compared to extended summer (32.9 nmol/L vs. 44.1 nmol/L, P < 0.001). Compared to those who attended their first antenatal visit during extended summer, extended winter was associated with increased HOMA-IR in early-pregnancy (46.7%) and late pregnancy (53.7%), independent of 25OHD <30 nmol/L and confounders. Early pregnancy 25OHD <30 nmol/L and extended winter were independently associated with significantly higher fasting glucose in late pregnancy (B = 0.15 and 0.13, respectively).Conclusions: Women who attended their first antenatal visit during the months of extended winter were more likely to have raised insulin resistance in early pregnancy, which had a lasting association to 28 weeks, and was independent of 25OHD. Our novel findings imply that seasonal variation in insulin resistance may not be fully explained by differences in vitamin D status. This could reflect circannual rhythm or seasonal lifestyle behaviours, and requires further exploration.Trial registration: ISRCTN registry, ISRCTN54392969, date of registration: 22/04/2009, retrospectively registered

Cloning and heterologous expression of bovine pyroglutamyl peptidase type-1 in Escherichia coli : purification , biochemical and kinetic characterisation

We describe the cloning, expression and purification of the bovine XM866409 form of pyroglutamyl-aminopeptidase I. The amino acid sequence, deduced from the nucleotide sequence, revealed that it consists of 209 amino acid residues and showed to have 98% homology with the human AJ278828 form of the enzyme. Three amino acid residues at positions 81, 205 and 208 were found to vary among the two sequences. The bovine enzyme was expressed in XL10-gold Esherichia coli cells. Immobilizied Ni-ion affinity chromatography was used to purify the expressed protein resulting in a yield of 3.3mg of PAP1 per litre culture. The purified enzyme had a specific activity of 1700 units/ml. SDS-PAGE produced a single band for bovine PAP1 with a molecular weight of ~23-24 kDa which is in good agreement with previously reported data on PAP1. Kinetic constants Km and Kcat were 59μΜ and 3.5s-1, respectively. It possessed an optimum pH between 9-9.5, a temperature of 37°C and showed an absolute requirement for a thiol-reducing agent (10mM DTT). EDTA didn’t prove to have an effect on enzyme activity. Competitive inhibition was seen with pyroglutamyl peptides pGlu-His-Pro-NH2 (TRH; Ki= 44.1 uM), pGlu-Ala- OH (Ki=141 uM) and pGlu-Val-OH (Ki=652.17)

Microarray analysis of genes associated with cell surface NIS protein levels in breast cancer

<p>Abstract</p> <p>Background</p> <p>Na⁺/I^-symporter (NIS)-mediated iodide uptake allows radioiodine therapy for thyroid cancer. NIS is also expressed in breast tumors, raising potential for radionuclide therapy of breast cancer. However, NIS expression in most breast cancers is low and may not be sufficient for radionuclide therapy. We aimed to identify biomarkers associated with NIS expression such that mechanisms underlying NIS modulation in human breast tumors may be elucidated.</p> <p>Methods</p> <p>Published oligonucleotide microarray data within the National Center for Biotechnology Information Gene Expression Omnibus database were analyzed to identify gene expression tightly correlated with NIS mRNA level among human breast tumors. NIS immunostaining was performed in a tissue microarray composed of 28 human breast tumors which had corresponding oligonucleotide microarray data available for each tumor such that gene expression associated <it>w</it>ith cell surface NIS protein level could be identified.</p> <p>Results and Discussion</p> <p>NIS mRNA levels do not vary among breast tumors or when compared to normal breast tissues when detected by Affymetrix oligonucleotide microarray platforms. Cell surface NIS protein levels are much more variable than their corresponding NIS mRNA levels. Despite a limited number of breast tumors examined, our analysis identified cysteinyl-tRNA synthetase as a biomarker that is highly associated with cell surface NIS protein levels in the ER-positive breast cancer subtype.</p> <p>Conclusions</p> <p>Further investigation on genes associated with cell surface NIS protein levels within each breast cancer molecular subtype may lead to novel targets for selectively increasing NIS expression/function in a subset of breast cancers patients.</p

Carotenoids Play a Positive Role in the Degradation of Heterocycles by Sphingobium yanoikuyae

BACKGROUND: Microbial oxidative degradation is a potential way of removing pollutants such as heterocycles from the environment. During this process, reactive oxygen species or other oxidants are inevitably produced, and may cause damage to DNA, proteins, and membranes, thereby decreasing the degradation rate. Carotenoids can serve as membrane-integrated antioxidants, protecting cells from oxidative stress. FINDINGS: Several genes involved in the carotenoid biosynthetic pathway were cloned and characterized from a carbazole-degrading bacterium Sphingobium yanoikuyae XLDN2-5. In addition, a yellow-pigmented carotenoid synthesized by strain XLDN2-5 was identified as zeaxanthin that was synthesized from β-carotene through β-cryptoxanthin. The amounts of zeaxanthin and hydrogen peroxide produced were significantly and simultaneously enhanced during the biodegradation of heterocycles (carbazole < carbazole + benzothiophene < carbazole + dibenzothiophene). These higher production levels were consistent with the transcriptional increase of the gene encoding phytoene desaturase, one of the key enzymes for carotenoid biosynthesis. CONCLUSIONS/SIGNIFICANCE: Sphingobium yanoikuyae XLDN2-5 can enhance the synthesis of zeaxanthin, one of the carotenoids, which may modulate membrane fluidity and defense against intracellular oxidative stress. To our knowledge, this is the first report on the positive role of carotenoids in the biodegradation of heterocycles, while elucidating the carotenoid biosynthetic pathway in the Sphingobium genus

Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level

An examination of whether associations exist between maternal and neonatal 25OHD and infant size and adiposity at birth, 6–9 months and 2–2.5 years of age – a longitudinal observational study from the ROLO study

Background: Vitamin D status in pregnancy and offspring bone health effects are well established, yet limited knowledge exists on the effect of maternal vitamin D status on offspring size/adiposity. This study examines the association of early (13 weeks), late (28 weeks) pregnancy and neonatal (umbilical) 25-hydroxyvitamin D (25OHD) on offspring size/adiposity.Methods: This analysis included mother-infant pairs from the ROLO study at birth (n = 292), 6–9 months (n = 160) and 2–2.5 years (n = 287) postpartum.Results: Using Institute of Medicine 2011 Report criteria, 30% of women in early pregnancy and 38% in late pregnancy were at risk of vitamin D deficiency (25OHD < 30 nmol/L). Birthweight was negatively associated with early-pregnancy 25OHD (p = 0.004) and neonatal 25OHD (p < 0.001). Birth length was not associated with 25OHD. Neonatal measures of overall adiposity were negatively associated with neonatal 25OHD (p = 0.001, and p = <0.001 respectively). At 2–2.5 years there was a negative association between weight-for-age z-score and early-pregnancy 25OHD (p < 0.041).Conclusions: Maternal and neonatal 25OHD were negatively associated with offspring size/adiposity at birth and offspring weight-for-age at 2–2.5 years. Results may not reflect a general population replete in vitamin D, due to high prevalence of macrosomia and high risk of deficiency in this cohort. Improvement of pregnancy vitamin D status remains a public health concern.Trial registration: Current Controlled Trials ISRCTN54392969. 22/04/2009 retrospectively registered