The thermodynamic properties of 39 polybrominated diphenyl ethers (PBDEs) in the ideal gas phase have been calculated using Gaussian 03 on the B3LYP/6-31G(d)//B3LYP/6-31G(d) level. Their ...thermodynamic and other physicochemical properties show a strong dependence on the bromine substitution pattern. The PBDE congeners' enthalpies of formation increase with an increasing number of bromines. The thermodynamic properties of congeners with the same number of bromines also show dependence on the bromine substitution pattern, especially for ortho-substituted congeners. PBDE congeners with one phenyl ring fully brominated, such as 2,3,4,5,6-PeBDE, 2,3,4,4‘,5,6-HxBDE, 2,2‘,3,4,4‘,5,6-HpBDE, and 2,3,3‘,4,4‘,5,6-HpBDE, were found to be the least stable among the analogues. The effects of bromine substitution pattern have been quantitatively studied by group additivity method (GAM) based on the output of the theoretical calculations. The results of the GAM were consistent with theoretical calculations, proving that theoretical calculations are reliable. Furthermore, the GAM model can be used to predict the thermodynamic properties for all of the 209 PBDE congeners.
A molecular and isotopic study of sediment cores from a sinkhole lake, Mud Lake, Florida, USA, was performed in order to relate documented changes in the regional terrestrial vegetation and water ...table over the last ∼5500 years to molecular and isotopic proxies for biological sources of organic matter to the lake sediments. Temporal shifts in the source of organic matter to the sediment, as determined by the stable carbon-isotope composition of bulk organic matter and biomarkers, correspond with previously defined regional scale transitions in forest ecosystems (
Quercus to
Pinus at ∼5500
14C yr BP and
Taxodium expansion at 2500
14C yr BP) and coincident increases in the Floridan water table. The
δ
13C values for total sedimentary organic carbon showed a shift from terrestrial and aquatic macrophyte sources (−27.8‰, in sediments dated at ∼5400
14C yr BP) within the basal peat, to a cyanobacterial-dominated sapropel (−18.1‰) at the surface. A comparison of the δ
13C values of bulk sediment and biomarkers representative of cyanobacterial and algal input (e.g. 7- and 8-methylheptadecane and the
n-alkane C
17) indicates that the present shallow lake was fully developed by ∼2400
14C yr BP. Differences among the
δ
13C values of specific biomarkers derived from vascular plants (C
29 and C
31
n-alkanes and CuO lignin oxidation products) and from cyanobacteria and algae are nearly equivalent in magnitude to the shift recorded in
δ
13C of TOC, indicating their effective use as source proxies in this system.
Electrocardiogram (ECG) monitoring is a critical tool in patient care, but its utility is often balanced with frustration from clinicians who are constantly distracted by false alarms. This has ...motivated the need to readdress the major factors that contribute to ECG noise with the goal of reducing false alarms. In this study, we describe a previously unreported phenomenon in which ECG noise can result from an unintended interaction between two systems: 1) the dc lead-off circuitry that is used to detect whether electrodes fall off the patient; and 2) the right-leg drive (RLD) system that is responsible for reducing ac common-mode noise that couples into the body. Using a circuit model to study this interaction, we found that in the presence of a dc lead-off system, even moderate increases in the right-leg skin-electrode resistance can cause the RLD amplifier to saturate. Such saturation can produce ECG noise because the RLD amplifier will no longer be capable of attenuating ac common-mode noise on the body. RLD saturation is particularly a problem for modern ECG monitors that use low-voltage supply levels. For example, for a 12-lead ECG and a 2 V power supply, saturation will occur when the right-leg electrode resistance reaches only 2 MΩ. We discuss several design solutions that can be used in low-voltage monitors to avoid RLD saturation.
Thanks to Vandana Dev, a preschool teacher and an adjunct instructor at Mission College, Santa Clara, and at San Jose City College, for her analysis; other groups who worked on this case include ...participants in a Directors Leadership Academy training sponsored by Smart Start of Mecklenburg County, North Carolina; participants in a training of trainers session at the Oregon AEYC Conference; and students in the ED 200 class on professionalism, at Portland Community College, in Oregon. Core values The following three core values are particularly applicable to this situation: ∂ Base our work on knowledge of how children develop and learn ∂ Appreciate and support the bond between the child and family ∂ Respect diversity in children, families, and colleagues Ideals and principles Respondents identified a number of items in the Code-specifically in the sections addressing our responsibilities to children and families-that could guide their thinking. ...the situation described by Rosa Romero involved a Hispanic family whose first language was Spanish. The staff collectively believe that in addition to building children's imaginations, dramatic play enhances their social and communication skills and is an integral part of the learning process that gives children opportunities to develop abstract thinking, literacy, math, and social studies skills.
Nutritional factors are known to influence arsenic metabolism in adults, and poor nutritional status--as reflected in part by a lack of various B vitamins and antioxidants--is thought to confer ...greater susceptibility to arsenic toxicity. Now researchers working in Bangladesh have reported that deficits in the B vitamin folate and the amino acid cysteine may adversely influence arsenic metabolism in children EHP 117:825-831; Hall et al.. The research team also found that, compared with adults, children may metabolize arsenic more efficiently and excrete it more readily, regardless of folate status.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background and aim: Widespread applicability of tissue-based mRNA expression screening for Barrett esophagus (BE) is likely to require (1) accurate methods for assaying archival formalin-fixed, ...paraffin-embedded (FFPE) histopathology specimens taken at endoscopy, and (2) validation studies of promising biomarkers in different patient cohorts.
Results: 30 genes were significantly differentially expressed by histopathology tissue type. The direction and magnitude of the differences were very similar to those found in previous studies using fresh frozen tissues. Novel upregulated genes were TSPAN8 (also known as CO-029), TSPAN24 (CD151), EGR1 and TCIRG1. Novel downregulated genes were DPYD, TSPAN29 (CD9) and Ets1. Strong associations between histopathology type and gene expression were observed with the overexpressed genes: cyclo-oxygenase-2 (COX-2), for which histopathology type explained 77.7% of the variation in expression, TSPAN1 (73.5%), TSPAN8 (62.9%), SPARC (62.1%), MMP7 (50.8%); and the under-expressed genes ADH7 (53.7%), APC (58.2%), RAR-gamma (51.3%).
Methods: mRNA was isolated from 54 FFPE small endoscopic biopsies from patients with Barrett intestinal metaplasia (BE), esophageal adenocarcinoma (EAC), or control patients with a normal squamous-lined esophagus. Multiplexed tandem PCR (MT-PCR) was used to quantitate 50 selected candidate genes for BE and control genes in duplicate. Principal component analysis (PCA) was conducted to explore the presence of global differences in gene expression profiles. One-way analysis of variance (ANOVA) of the transformed data was used to identify genes that were differentially expressed between different histological subtypes. Differentially expressed genes with a fold change of ≥2 (upregulated) or ≤-2 (downregulated) are reported with the p value for each comparison (EAC vs. normal, EAC vs. BE and BE vs. normal). The Benjamini-Hochberg method was used to control the false discovery rate at 0.01 for all comparisons.
Conclusions: Alterations in expression of select genes are strongly associated with BE or EAC or both. This study's findings for many highly differentially expressed genes are very similar to those previously reported, suggesting that these genes should be tested further in longitudinal studies for their potential role as biomarkers of progression to more advanced Barrett disease.
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