Urinary concentrations of bisphenols and parabens and their association with attention, hyperactivity and impulsivity at adolescence

Background: Neurobehavioural disorder diagnoses have been increasing over the last decades, leading to heightened interest in the aetiological factors involved. Endocrine disrupting chemicals, such as parabens and bisphenols, have been suggested as one of those factors. It is unknown whether exposure during adolescence may affect neurobehavioural development. Objective: To determine whether urinary concentrations of parabens and bisphenols are associated with attention and concentration in adolescents, in general and sex-specific. Methods: We invited 188 adolescents (13–15 years old) for the follow-up birth cohort-study. Concentrations of five parabens and three bisphenols (BPA; BPF; BPS) were measured in morning urine after overnight fasting, using a validated LC-MS/MS method. Attention and concentration were assessed at the clinic with subtests of the Test of Everyday Attention in Children and the Dutch Attention Deficit Hyperactivity Disorder questionnaire (AVL), the latter being filled in by parents. Linear regression analyses were performed, adjusting for urine creatinine concentrations and potential confounding factors.Results: 101 (54%) adolescents participated (46 girls; 55 boys). Urinary paraben concentrations were higher in girls than in boys. Methylparaben was positively associated with attention in girls (p ≤ .05; B= −2.836; 95%CI= −5.175;−.497), ethylparaben negatively with hyperactivity (p ≤ .05; B= −1.864; 95%CI= −3.587;−.141). Butylparaben was associated with more optimal scores on parent reported attention. Propylparaben was negatively associated with scores on sustained auditory attention in girls (p ≤ .10; B=.444; 95%CI= −.009;.896). Bisphenol concentrations were not associated with scores on attention and concentration after adjusting for confounders.Conclusion: In 13–15-year-old Dutch adolescents, urinary concentrations of methylparaben and ethylparaben were associated with better attention and less hyperactivity, whereas a trend toward significance was found between higher urinary propylparaben concentrations and poorer attention. Bisphenol concentrations were not associated with attention and concentration after adjusting for confounders.</p

The initial step of DNA hairpin folding: a kinetic analysis using fluorescence correlation spectroscopy

Conformational fluctuations of single-stranded DNA (ssDNA) oligonucleotides were studied in aqueous solution by monitoring contact-induced fluorescence quenching of the oxazine fluorophore MR121 by intrinsic guanosine residues (dG). We applied fluorescence correlation spectroscopy as well as steady-state and time-resolved fluorescence spectroscopy to analyze kinetics of DNA hairpin folding. We first characterized the reporter system by investigating bimolecular quenching interactions between MR121 and guanosine monophosphate in aqueous solution estimating rate constants, efficiency and stability for formation of quenched complexes. We then studied the kinetics of complex formation between MR121 and dG residues site-specifically incorporated in DNA hairpins. To uncover the initial steps of DNA hairpin folding we investigated complex formation in ssDNA carrying one or two complementary base pairs (dC–dG pairs) that could hybridize to form a short stem. Our data show that incorporation of a single dC–dG pair leads to non-exponential decays for opening and closing kinetics and reduces rate constants by one to two orders of magnitude. We found positive activation enthalpies independent of the number of dC–dG pairs. These results imply that the rate limiting step of DNA hairpin folding is not determined by loop dynamics, or by mismatches in the stem, but rather by interactions between stem and loop nucleotides

Co-production of hydrogen and ethanol from glucose in Escherichia coli by activation of pentose-phosphate pathway through deletion of phosphoglucose isomerase (pgi) and overexpression of glucose-6-phosphate dehydrogenase (zwf) and 6-phosphogluconate dehydrogenase (gnd)

Background: Biologically, hydrogen (H-2) can be produced through dark fermentation and photofermentation. Dark fermentation is fast in rate and simple in reactor design, but H-2 production yield is unsatisfactorily low as < 4 mol H-2/ mol glucose. To address this challenge, simultaneous production of H-2 and ethanol has been suggested. Co-production of ethanol andH(2) requires enhanced formation of NAD(P) H during catabolism of glucose, which can be accomplished by diversion of glycolytic flux from the Embden-Meyerh-of-Parnas (EMP) pathway to the pentose-phosphate (PP) pathway in Escherichia coli. However, the disruption of pgi (phosphoglucose isomerase) for complete diversion of carbon flux to the PP pathway made E. coli unable to grow on glucose under anaerobic condition. Results: Here, we demonstrate that, when glucose-6-phosphate dehydrogenase (Zwf) and 6-phosphogluconate dehydrogenase (Gnd), two major enzymes of the PP pathway, are homologously overexpressed, E. coli.pgi can recover its anaerobic growth capability on glucose. Further, with additional deletions of Delta hycA,Delta hyaAB,Delta hybBC,Delta ldhA, and Delta frdAB, the recombinant.pgi mutant could produce 1.69 mol H-2 and 1.50 mol ethanol from 1 mol glucose. However, acetate was produced at 0.18 mol mol(-1) glucose, indicating that some carbon is metabolized through the Entner-Doudoroff (ED) pathway. To further improve the flux via the PP pathway, heterologous zwf and gnd from Leuconostoc mesenteroides and Gluconobacter oxydans, respectively, which are less inhibited by NADPH, were overexpressed. The new recombinant produced more ethanol at 1.62 mol mol(-1) glucose along with 1.74 mol H-2 mol(-1) glucose, which are close to the theoretically maximal yields, 1.67 mol mol(-1) each for ethanol andH(2). However, the attempt to delete the ED pathway in the.pgi mutant to operate the PP pathway as the sole glycolytic route, was unsuccessful. Conclusions: By deletion of pgi and overexpression of heterologous zwf and gnd in E. coli Delta hycA Delta hyaAB Delta hybBC Delta ldhA Delta frdAB, two important biofuels, ethanol andH(2), could be successfully co-produced at high yields close to their theoretical maximums. The strains developed in this study should be applicable for the production of other biofuels and biochemicals, which requires supply of excessive reducing power under anaerobic conditions

SAT-Based Combinational and Sequential Dependency Computation

We present an algorithm for computing both functional dependency and unateness of combinational and sequential Boolean func- tions represented as logic networks. The algorithm uses SAT-based tech- niques from Combinational Equivalence Checking (CEC) and Automatic Test Pattern Generation (ATPG) to compute the dependency matrix of multi-output Boolean functions. Additionally, the classical dependency definitions are extended to sequential functions and a fast approximation is presented to efficiently yield a sequential dependency matrix. Exten- sive experiments show the applicability of the methods and the improved robustness compared to existing approaches

Dissecting Oct3/4-Regulated Gene Networks in Embryonic Stem Cells by Expression Profiling

POU transcription factor Pou5f1 (Oct3/4) is required to maintain ES cells in an undifferentiated state. Here we show that global expression profiling of Oct3/4-manipulated ES cells delineates the downstream target genes of Oct3/4. Combined with data from genome-wide chromatin-immunoprecipitation (ChIP) assays, this analysis identifies not only primary downstream targets of Oct3/4, but also secondary or tertiary targets. Furthermore, the analysis also reveals that downstream target genes are regulated either positively or negatively by Oct3/4. Identification of a group of genes that show both activation and repression depending on Oct3/4 expression levels provides a possible mechanism for the requirement of appropriate Oct3/4 expression to maintain undifferentiated ES cells. As a proof-of-principle study, one of the downstream genes, Tcl1, has been analyzed in detail. We show that Oct3/4 binds to the promoter region of Tcl1 and activates its transcription. We also show that Tcl1 is involved in the regulation of proliferation, but not differentiation, in ES cells. These findings suggest that the global expression profiling of gene-manipulated ES cells can help to delineate the structure and dynamics of gene regulatory networks

Direct knock-on of desolvated ions governs strict ion selectivity in K+ channels

The seeming contradiction that K+ channels conduct K+ ions at maximal throughput rates while not permeating slightly smaller Na+ ions has perplexed scientists for decades. Although numerous models have addressed selective permeation in K+ channels, the combination of conduction efficiency and ion selectivity has not yet been linked through a unified functional model. Here, we investigate the mechanism of ion selectivity through atomistic simulations totalling more than 400 μs in length, which include over 7,000 permeation events. Together with free-energy calculations, our simulations show that both rapid permeation of K+ and ion selectivity are ultimately based on a single principle: the direct knock-on of completely desolvated ions in the channels' selectivity filter. Herein, the strong interactions between multiple 'naked' ions in the four filter binding sites give rise to a natural exclusion of any competing ions. Our results are in excellent agreement with experimental selectivity data, measured ion interaction energies and recent two-dimensional infrared spectra of filter ion configurations

Observations on comatose survivors of cardiopulmonary resuscitation with generalized myoclonus

BACKGROUND: There is only limited data on improvements of critical medical care is resulting in a better outcome of comatose survivors of cardiopulmonary resuscitation (CPR) with generalized myoclonus. There is also a paucity of data on the temporal dynamics of electroenephalographic (EEG) abnormalities in these patients. METHODS: Serial EEG examinations were done in 50 comatose survivors of CPR with generalized myoclonus seen over an 8 years period. RESULTS: Generalized myoclonus occurred within 24 hours after CPR. It was associated with burst-suppression EEG (n = 42), continuous generalized epileptiform discharges (n = 5), alpha-coma-EEG (n = 52), and low amplitude (10 μV <) recording (n = 1). Except in 3 patients, these EEG-patterns were followed by another of these always nonreactive patterns within one day, mainly alpha-coma-EEG (n = 10) and continuous generalized epileptiform discharges (n = 9). Serial recordings disclosed a variety of EEG-sequences composed of these EEG-patterns, finally leading to isoelectric or flat recordings. Forty-five patients died within 2 weeks, 5 patients survived and remained in a permanent vegetative state. CONCLUSION: Generalized myoclonus in comatose survivors of CPR still implies a poor outcome despite advances in critical care medicine. Anticonvulsive drugs are usually ineffective. All postanoxic EEG-patterns are transient and followed by a variety of EEG sequences composed of different EEG patterns, each of which is recognized as an unfavourable sign. Different EEG-patterns in anoxic encephalopathy may reflect different forms of neocortical dysfunction, which occur at different stages of a dynamic process finally leading to severe neuronal loss

β-Catenin Signaling Increases during Melanoma Progression and Promotes Tumor Cell Survival and Chemoresistance

Beta-catenin plays an important role in embryogenesis and carcinogenesis by controlling either cadherin-mediated cell adhesion or transcriptional activation of target gene expression. In many types of cancers nuclear translocation of beta-catenin has been observed. Our data indicate that during melanoma progression an increased dependency on the transcriptional function of beta-catenin takes place. Blockade of beta-catenin in metastatic melanoma cell lines efficiently induces apoptosis, inhibits proliferation, migration and invasion in monolayer and 3-dimensional skin reconstructs and decreases chemoresistance. In addition, subcutaneous melanoma growth in SCID mice was almost completely inhibited by an inducible beta-catenin knockdown. In contrast, the survival of benign melanocytes and primary melanoma cell lines was less affected by beta-catenin depletion. However, enhanced expression of beta-catenin in primary melanoma cell lines increased invasive capacity in vitro and tumor growth in the SCID mouse model. These data suggest that beta-catenin is an essential survival factor for metastatic melanoma cells, whereas it is dispensable for the survival of benign melanocytes and primary, non-invasive melanoma cells. Furthermore, beta-catenin increases tumorigenicity of primary melanoma cell lines. The differential requirements for beta-catenin signaling in aggressive melanoma versus benign melanocytic cells make beta-catenin a possible new target in melanoma therapy