The double [3+2] photocycloaddition reaction

One of a synthetic organic chemists‟ greatest challenges is to create step-efficient routes toward compounds with high molecular complexity. Therefore, reactions such as the meta photocycloaddition of an olefin to a benzene derivative, which provide more than one bond in a single step are of significant importance. It this remarkable reaction three new σ bonds, three new rings and up to six new stereocenters are formed simultaneously. Additional complexity can be added by tethering the two reacting partners together and this form of the reaction has found many uses in natural product synthesis. In this work a remarkable double [3+2] photocycloaddition reaction is reported that results in the formation of a complex cis, cis, cis, trans-[5, 5, 5, 5] fenestrane derivative from a simple flat aromatic acetal with two branching alkenes. During this dramatic transformation four carboncarbon bonds, five new rings and seven new stereocenters are created in a single one-pot process using only UV light. The reaction occurs in a sequential manner from the linear meta photocycloadduct, via a secondary [3+2] addition of the alkene across the cyclopropane of the adduct. In addition, an angular meta photocycloadduct also produced in the initial addition step, undergoes an alternative fragmentation-translocation photoreaction to afford a silphinene-like angular tricyclic compound. In this work the investigation of this newly discovered process is discussed via the synthesis and subsequent irradiation of a series of photosubstrates containing different functional groups in the arene-alkene tether. In addition, attempts toward the synthesis of alternative structures using the same double [3+2] photocycloaddition are reported

Synthesis, characterization, and photocatalytic activity of pure and N-, B-, or Ag- Doped TiO2

This article reports the synthesis and characterization of pure and N-, B-, and Ag-doped TiO2 and the ability of these oxides to photodegrade methylene blue (MB) under sunlight or UV-ABC radiation. The compounds were synthesized using the sol-gel method and characterized by scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Photocatalytic efficiency was significantly increased by N-doping, resulting in 98% MB decomposition under UV-ABC irradiation for 180 min. Ag- and B-doped TiO2 lowered MB degradation rates to 52 and 73%, respectively, compared with pure TiO2. The same behavior was observed with exposure to UV-Vis, with 88, 65, 60, and 42% MB removal with N-doped, pure, B-doped, and Ag-doped TiO2, respectively. Under visible light alone, N-doped TiO2 exhibited higher photocatalytic efficiency than commercial P25-type TiO2. Photocatalysis with N-doped TiO2 proved to be a promising alternative for MB degradation, given the potential of employing solar energy, thus minimizing operating costs

Photoswitchable diacylglycerols enable optical control of protein kinase C.

Increased levels of the second messenger lipid diacylglycerol (DAG) induce downstream signaling events including the translocation of C1-domain-containing proteins toward the plasma membrane. Here, we introduce three light-sensitive DAGs, termed PhoDAGs, which feature a photoswitchable acyl chain. The PhoDAGs are inactive in the dark and promote the translocation of proteins that feature C1 domains toward the plasma membrane upon a flash of UV-A light. This effect is quickly reversed after the termination of photostimulation or by irradiation with blue light, permitting the generation of oscillation patterns. Both protein kinase C and Munc13 can thus be put under optical control. PhoDAGs control vesicle release in excitable cells, such as mouse pancreatic islets and hippocampal neurons, and modulate synaptic transmission in Caenorhabditis elegans. As such, the PhoDAGs afford an unprecedented degree of spatiotemporal control and are broadly applicable tools to study DAG signaling

The importance of maternal insulin resistance throughout pregnancy on neonatal adiposity

Background: Although previous studies evaluated the association of maternal health parameters with neonatal adiposity, little is known regarding the complexity of the relationships among different maternal health parameters throughout pregnancy and its impact on neonatal adiposity. Objectives: To evaluate the direct and indirect associations between maternal insulin resistance during pregnancy, in women with obesity, and neonatal adiposity. In addition, associations between maternal fasting glucose, triglycerides (TG), non-esterified fatty acids (NEFA), and neonatal adiposity were also assessed. Methods: This is a longitudinal, secondary analysis of the DALI study, an international project conducted in nine European countries with pregnant women with obesity. Maternal insulin resistance (HOMA-IR), fasting glucose, TG, and NEFA were measured three times during pregnancy (<20, 24-28, and 35-37 weeks of gestation). Offspring neonatal adiposity was estimated by the sum of four skinfolds. Structural equation modelling was conducted to evaluate the direct and indirect relationships among the variables of interest. Results: Data on 657 mother-infant pairs (50.7% boys) were analysed. Neonatal boys exhibited lower mean sum of skinfolds compared to girls (20.3 mm, 95% CI 19.7, 21.0 vs 21.5 mm, 95% CI 20.8, 22.2). In boys, maternal HOMA-IR at <20 weeks was directly associated with neonatal adiposity (β = 0.35 mm, 95% CI 0.01, 0.70). In girls, maternal HOMA-IR at 24-28 weeks was only indirectly associated with neonatal adiposity, which implies that this association was mediated via maternal HOMA-IR, glucose, triglycerides, and NEFA during pregnancy (β = 0.26 mm, 95% CI 0.08, 0.44). Conclusions: The timing of the role of maternal insulin resistance on neonatal adiposity depends on fetal sex. Although the association was time-dependent, maternal insulin resistance was associated with neonatal adiposity in both sexes

Alexithymia, emotion processing and social anxiety in adults with ADHD

<p>Abstract</p> <p>Objective</p> <p>Given sparse research on the issue, this study sought to shed light upon the interactions of alexithymia, emotion processing, and social anxiety in adults with attention-deficit hyperactivity disorder (ADHD).</p> <p>Subjects and methods</p> <p>73 German adults with ADHD according to DSM-IV diagnostic criteria participated. We used the Toronto Alexithymia Scale (TAS-20) to assess alexithymia, the Social Phobia Scale (SPS) and the Social Interaction Anxiety Scale (SIAS) to assess different features of social anxiety, and we applied the German 'Experience of Emotions Scale' (SEE) to measure emotion processing.</p> <p>Results</p> <p>40% of the sample were found to meet the DSM-IV criteria of social anxiety disorder, and about 22% were highly alexithymic according to a TAS-20 total score ≥ 61; however, the mean TAS-20 total score of 50.94 ± 9.3 was not much higher than in community samples. Alexithymic traits emerged to be closely linked to emotion processing problems, particularly 'difficulty accepting own emotions', and to social anxiety features.</p> <p>Discussion/conclusion</p> <p>Our findings suggest interactions of alexithymia, emotion processing dysfunction, and social anxiety in adults with ADHD, which may entail the therapeutic implication to thoroughly instruct these patients to identify, accept, communicate, and regulate their emotions to aid reducing interaction anxiety.</p

Poor glycated haemoglobin control and adverse pregnancy outcomes in type 1 and type 2 diabetes mellitus: Systematic review of observational studies

BACKGROUND: Glycaemic control in women with diabetes is critical to satisfactory pregnancy outcome. A systematic review of two randomised trials concluded that there was no clear evidence of benefit from very tight versus tight glycaemic control for pregnant women with diabetes. METHODS: A systematic review of observational studies addressing miscarriage, congenital malformations and perinatal mortality among pregnant women with type 1 and type 2 diabetes was carried out. Literature searches were performed in MEDLINE, EMBASE, CINAHL and Cochrane Library. Observational studies with data on glycated haemoglobin (HbA(1c)) levels categorised into poor and optimal control (as defined by the study investigators) were selected. Relative risks and odds ratios were calculated for HbA(1c )and pregnancy outcomes. Adjusted relative risk estimates per 1-percent decrease in HbA(1c )were calculated for studies which contained information on mean and standard deviations of HbA(1c). RESULTS: The review identified thirteen studies which compared poor versus optimal glycaemic control in relation to maternal, fetal and neonatal outcomes. Twelve of these studies reported the outcome of congenital malformations and showed an increased risk with poor glycaemic control, pooled odds ratio 3.44 (95%CI, 2.30 to 5.15). For four of the twelve studies, it was also possible to calculate a relative risk reduction of congenital malformation for each 1-percent decrease in HbA(1c), these varied from 0.39 to 0.59. The risk of miscarriage was reported in four studies and was associated with poor glycaemic control, pooled odds ratio 3.23 (95%CI, 1.64 to 6.36). Increased perinatal mortality was also associated with poor glycaemic control, pooled odds ratio 3.03 (95%CI, 1.87 to 4.92) from four studies. CONCLUSION: This analysis quantifies the increase in adverse pregnancy outcomes in women with diabetes who have poor glycaemic control. Relating percentage risk reduction in HbA(1c )to relative risk of adverse pregnancy events may be useful in motivating women to achieve optimal control prior to conception

The importance of maternal insulin resistance throughout pregnancy on neonatal adiposity

Background: Although previous studies evaluated the association of maternal health parameters with neonatal adiposity, little is known regarding the complexity of the relationships among different maternal health parameters throughout pregnancy and its impact on neonatal adiposity. Objectives: To evaluate the direct and indirect associations between maternal insulin resistance during pregnancy, in women with obesity, and neonatal adiposity. In addition, associations between maternal fasting glucose, triglycerides (TG), non-esterified fatty acids (NEFA), and neonatal adiposity were also assessed. Methods: This is a longitudinal, secondary analysis of the DALI study, an international project conducted in nine European countries with pregnant women with obesity. Maternal insulin resistance (HOMA-IR), fasting glucose, TG, and NEFA were measured three times during pregnancy (<20, 24-28, and 35-37 weeks of gestation). Offspring neonatal adiposity was estimated by the sum of four skinfolds. Structural equation modelling was conducted to evaluate the direct and indirect relationships among the variables of interest. Results: Data on 657 mother-infant pairs (50.7% boys) were analysed. Neonatal boys exhibited lower m

Technical and Comparative Aspects of Brain Glycogen Metabolism.

It has been known for over 50 years that brain has significant glycogen stores, but the physiological function of this energy reserve remains uncertain. This uncertainty stems in part from several technical challenges inherent in the study of brain glycogen metabolism, and may also stem from some conceptual limitations. Factors presenting technical challenges include low glycogen content in brain, non-homogenous labeling of glycogen by radiotracers, rapid glycogenolysis during postmortem tissue handling, and effects of the stress response on brain glycogen turnover. Here, we briefly review aspects of glycogen structure and metabolism that bear on these technical challenges, and discuss ways these can be overcome. We also highlight physiological aspects of glycogen metabolism that limit the conditions under which glycogen metabolism can be useful or advantageous over glucose metabolism. Comparisons with glycogen metabolism in skeletal muscle provide an additional perspective on potential functions of glycogen in brain