Polycyclic aromatic hydrocarbons and their oxygenated derivatives in the urban atmosphere of Athens.

Ambient samples of coarse and fine organic particulate matter collected from two urban sites in the city of Athens over one warm and one cold period have been solvent-extracted and quantitatively characterized by gas chromatography-mass spectrometry for their content of polycyclic aromatic hydrocarbons (PAHs) and oxidized PAHs (oxyPAHs). Variable concentrations were observed for the two distinct monthly periods representing a cold, dry period and a summer period, relating to strong local primary emissions and to lower emissions with more stable meteorological conditions, respectively. Additionally, gaseous concentrations of selected PAHs were calculated, revealing that the relative proportions between gaseous and particle phase of individual compounds may differ significantly between summer and late winter, reflecting changes in PAH emission sources and climate conditions. In fact almost all of SigmaPAHs were attributed to combustion sources (82-92%), while more than half are considered as comprising of probable human carcinogens (47-62%). Traffic was confirmed as the major contributor of PAHs when appropriate diagnostic ratios and traffic marker compounds were used. This approach also led to the estimation of diesel versus petrol contribution to the atmospheric PAH burden, using the methylphenanthrene to phenanthrene ratio. The fourteen oxygenated polycyclic compounds that were quantified had greater concentrations in the colder period. Among these compounds 9,10-phenanthrenequinone, 1-pyrenecarboxaldehyde and 9H-fluoren-9-one had the highest concentrations.

Origins of n-alkanes, carbonyl compounds and molecular biomarkers in atmospheric fine and coarse particles of Athens, Greece.

The abundance and origin of aliphatic hydrocarbons, carbonyl compounds and molecular biomarkers found in the aliphatic fraction of PM(10-2.5) and PM(2.5) in the centre of Athens Greece are discussed in an attempt to reveal seasonal air pollution characteristics of the conurbation. Each extract was fractionated into individual compound classes and was analyzed using gas chromatography coupled to mass spectrometry. Normal alkanes, ranging from C(14) to C(35), were abundant in PM(10-2.5) and PM(2.5) samples during both sampling campaigns. The daily concentration of total n-alkanes was up to 438 ng m(-3) for PM(10-2.5) and up to 511 ng m(-3) for PM(2.5). Additionally, gaseous concentrations of n-alkanes were calculated, revealing that the relative proportions between gaseous and particle phases of individual compounds may differ significantly between summer and late winter. Normal alkanals and alkan-2-ones were only detected in the fine fraction of particulate matter and their concentrations were much lower than the n-alkane concentrations. Several geochemical parameters were used to qualitatively reconcile the sources of organic aerosol. The carbon preference index (CPI) of the coarse particles in August had the highest value, while in March the leaf wax contribution decreased significantly and the CPI value was very close to unity for both sites. Maximum concentrations of carbonyl compounds were reported in the range of C(15)-C(20), demonstrating that they were formed from anthropogenic activity or from atmospheric oxidative processes. 6, 10, 14-trimethylpentadecan-2-one, a marker of biogenic input, was also detected in our samples. Molecular biomarker compounds confirmed that ca. 60% of the aliphatic fraction on the sampled atmospheric particles originated from petroleum and not from any contemporary biogenic sources. Pristane and phytane were detected in the fine fraction with their presence indicating sources of fossil fuel in the range of C(16)-C(20). At all sites the 17alpha(Eta),21beta(Eta) hopane series was the most abundant hopane group.

Glycogen phosphorylase inhibitors: a free energy perturbation analysis of glucopyranose spirohydantoin analogues.

GP catalyzes the phosphorylation of glycogen to Glc-1-P. Because of its fundamental role in the metabolism of glycogen, GP has been the target for a systematic structure-assisted design of inhibitory compounds, which could be of value in the therapeutic treatment of type 2 diabetes mellitus. The most potent catalytic-site inhibitor of GP identified to date is spirohydantoin of glucopyranose (hydan). In this work, we employ MD free energy simulations to calculate the relative binding affinities for GP of hydan and two spirohydantoin analogues, methyl-hydan and n-hydan, in which a hydrogen atom is replaced by a methyl- or amino group, respectively. The results are compared with the experimental relative affinities of these ligands, estimated by kinetic measurements of the ligand inhibition constants. The calculated binding affinity for methyl-hydan (relative to hydan) is 3.75 +/- 1.4 kcal/mol, in excellent agreement with the experimental value (3.6 +/- 0.2 kcal/mol). For n-hydan, the calculated value is 1.0 +/- 1.1 kcal/mol, somewhat smaller than the experimental result (2.3 +/- 0.1 kcal/mol). A free energy decomposition analysis shows that hydan makes optimum interactions with protein residues and specific water molecules in the catalytic site. In the other two ligands, structural perturbations of the active site by the additional methyl- or amino group reduce the corresponding binding affinities. The computed binding free energies are sensitive to the preference of a specific water molecule for two well-defined positions in the catalytic site. The behavior of this water is analyzed in detail, and the free energy profile for the translocation of the water between the two positions is evaluated. The results provide insights into the role of water molecules in modulating ligand binding affinities. A comparison of the interactions between a set of ligands and their surrounding groups in X-ray structures is often used in the interpretation of binding free energy differences and in guiding the design of new ligands. For the systems in this work, such an approach fails to estimate the order of relative binding strengths, in contrast to the rigorous free energy treatment.

Affecting factors in second language learning.

The present study investigated the influence of sex, handedness, level in second language (L2) and Faculty choice on the performance of phonological, syntactical and semantic tasks in L2. Level in L2 and sex were the most affecting factors. Subjects who achieved higher scores on L2 tasks had strong second language aptitude skills since they were those who had obtained a professional degree in the second language. Females performed better than males in syntax and semantics which is explained by the general female superiority on verbal tasks based on differences in hemispheric specialization for language functions between the sexes. Handedness and Faculty choice on the part of the participants had an impact on our results but only when combined with other factors.

Periodontitis and systemic inflammation: control of the local infection is associated with a reduction in serum inflammatory markers.

Severe periodontitis is associated with elevated inflammatory markers in otherwise healthy populations. However, the nature of this association has not been determined. Our aim was to assess whether the degree of response to periodontal therapy was associated with changes in serological markers of systemic inflammation. Ninety-four systemically healthy subjects with severe generalized periodontitis participated in a prospective six-month blind intervention trial. Periodontal parameters and inflammatory markers [C-reactive Protein (CRP) and Interleukin-6 (IL-6)] were evaluated prior to and 2 and 6 mos after delivery of standard non-surgical periodontal therapy. Six months after treatment, significant reductions in serum IL-6 (p < 0.001, median decrease 0.2 ng/L, 95% CI 0.1-0.4 ng/L) and CRP (p < 0.0001, median decrease 0.5 mg/L, 95% CI 0.4-0.7) were observed. Decreases in inflammatory markers were significant in subjects with above average clinical response to periodontal therapy after correction for possible confounders. Periodontitis may add to the systemic inflammatory burden of affected individuals.

Fetal sensitivity to testosterone, left-handedness and development of bronchial asthma: a new approach.

In contrast to Geschwind, Behan and Galaburda (GBG) theory, there is strong evidence that inheritance through maternal line is responsible for the coexistence of asthma and left-handedness early in childhood. A new model that incorporates GBG's theory and maternal inheritance is proposed. This hypothesis suggests that maternal atopy is the most important factor in the evolution of asthma and that GBG's theory applies mainly in childhood. An inherited enhanced sensitivity of fetus to testosterone may be the underlying mechanism that leads to the development of bronchial asthma.

Cognitive status in Down syndrome individuals with sleep disordered breathing deficits (SDB).

Twelve subjects with Down syndrome underwent polysomnographic studies during night sleep and performed the Mini-Mental state test and the Raven Progressive Matrices (RPM), sets A, B, and B(1). Sleep-disordered breathing (SDB) deficits were observed in Down syndrome individuals and their Mini-Mental and RPM scores were extremely low. Regression analysis of the results revealed that the number of apneas per hour was related with the results of the RPM, set A, which were also related with the orientation of Mini-Mental test, indicating that the more apneas an individual has the more difficulties he has in the kind of visuoperceptual skills, including orientation, associated with normal right hemisphere functioning, which are tested by set A of the RPM.

Hemispheric asymmetries of visual ERPs in left-handed bilinguals.

ERPs (N1, P1, N2, P2) obtained from left and right occipital and temporal lobes were elicited in 30 left-handed highly proficient bilingual males in response to visually presented linguistic stimuli. The absence of statistically significant(P = < or =0.05) differences between left and right occipital and temporal lobes in all the components of the waveforms obtained, indicates a bilateral pattern of lateralization in left-handed males for both their native and foreign language.

Visual field asymmetries for rhyme and semantic tasks in fluent and nonfluent bilinguals.

A tachistoscopic study investigated hemispheric specialization among fluent and nonfluent bilinguals for rhyme and semantic tasks in both their languages. Fluent bilinguals gave faster responses and made fewer errors in their responses to the words presented in the RVF(LH) while the opposite happened for nonfluent, which indicates greater RH participation in the first stages of a second language. Fluent bilinguals performed better not only in the second but also in their native language, suggesting superior language skills on the part of fluent bilinguals. A LVF(RH) superiority was obtained for semantic tasks, indicating RH participation in semantic judgments. Another finding was a high ratio of first-born children among fluent bilinguals, potentially explained in terms of parental attitudes toward first- versus later born children.

Left-handedness and inheritance of bronchial asthma.

A statistically significant difference in mean laterality quotients of 15 asthmatic and 106 nonasthmatic children showed a coexistence of left-handedness and asthma early in life. It is suggested that this phenomenon is not only a fetal event as the Geschwind-Galaburda hypothesis claims but it is mainly based on maternal line inheritance.