Organophosphorus flame retardants (OPFRs) are a group of chemicals widely used in various everyday use products. Tris(2-chloroethyl)phosphate (TCEP) and tris(1-chloro-2-propyl)phosphate (TCPP) are ...one of the commonly used chemicals belonging to this group. Due to the need of limitation of the use of polybrominated diphenyl ethers (PBDEs) as retardants, the share of the compounds tested in our experiments in chemicals production systematically increases. There is limited information about the influence of halogenated OPFRs on living cells, especially on the immune system cells. That is why the aim of this study was to assess the impact of TCEP and TCPP on viability and morphological alterations of human peripheral blood mononuclear cells (PBMCs). The cells were incubated with selected flame retardants in the concentrations ranging from 0.001 to 1 mM for 24 h. It was found that TCEP at 1 mM and TCPP at 0.5 mM decreased viability of PBMCs, while only TCPP induced morphological alterations in the incubated cells. The results of our experiments suggest that TCPP is more cytotoxic than TCEP, which can be explained by the presence of methyl groups in the molecule of this compound. Similar to other studies, our data also suggest that OPFRs are suitable replacements for PBDEs.
Introduction
Delirium is a frequent and serious complication of cardiac surgery. However, the knowledge regarding pathogenesis of postoperative delirium is limited.
Objectives
To investigate whether ...increased levels of monocyte chemoattractant protein-1 (MCP-1) and hyper-sensitive C-Reactive Protein (hsCRP) are associated with postoperative delirium in cardiac surgery patients.
Methods
Patients were examined and screened for major depressive disorder (MDD) and cognitive impairment one day preoperatively, using the Mini International Neuropsychiatric Interview and The Mini-Mental State Examination Test. Blood samples were collected pre- and postoperatively for hsCRP and chemokine levels. Following surgical interventions, the Confusion Assessment Method for the Intensive Care Unit and the Memorial Delirium Assessment Scale with the cut-off score 10 were used to diagnose delirium.
Results
Postoperative delirium screening was found positive in 34% (61 of 177) of patients. Both, pre- and postoperative hsCRP, and preoperative MCP-1 levels were associated with postoperative delirium in univariate comparisons; p=0.001; p=0.0004; p < 0.001, respectively. However, according to a multivariate stepwise logistic regression analysis only MCP-1 concentration raised before surgery was independently associated with postoperative delirium, and related to advancing age of participants (Spearman’s Rank Correlation 0.192; p=0.0103). According to ROC analysis, the most optimal cut-off for MCP-1 concentration in predicting the development of delirium was 371.81 ng/ml with sensitivity of 77.0% and specificity of 58.6%.
Conclusions
The present study suggests that raised preoperative MCP-1 concentration is independently associated with delirium after cardiac surgery. Preoperative monitoring of pro-inflammatory markers combined with regular surveillance may be helpful in the prediction and early detection of postoperative delirium in this patient group.
Introduction
Coronary-artery bypass graft (CABG) surgery is known to improve cardiac function and decrease mortality, albeit, this method of treatment is associated with a high risk of postoperative ...delirium. The pathophysiology of delirium after cardiac surgery is largely unknown.
Objectives
To investigate whether oxidative stress reflected by decreased preoperative and postoperative plasma antioxidant capacity (AC) is independently associated with delirium after cardiac surgery. Furthermore, to assess whether the association between AC and the level of soluble receptor for advanced glycation end-products (sRAGE) exists.
Methods
The patients were examined 1 day preoperatively with the Mini International Neuropsychiatric Interview and MMSE test to screen for depression, anxiety disorders, and for cognitive impairment, respectively. Blood samples for AC and sRAGE levels were collected both preopertively and postoperatively. The CAM ICU and MDAS were used within the first 5 days postoperatively to screen for a diagnosis of delirium.
Results
Postoperative delirium developed in 34% (61 of 177) of participants. Multivariate stepwise logistic regression analysis revealed that patients with low baseline AC are at significantly increased risk of developing delirium. Moreover, preoperative AC levels were inversly correlated with postoperative sRAGE concentrations (Spearman’s Rank Correlation -0.198; p<0.05). The most optimal cutoff values of the preoperative and postoperative AC that predict the development of delirium were 1.720 mM and 1.893 mM, respectively.
Conclusions
Decreased plasma AC levels are associated with delirium after cardiac surgery and inversly correlated with post-surgery sRAGE concentration. This may be an important pathophysiological consideration in the increased risk of postoperative delirium seen in cardiac surgery patients.
We used the density functional theory to evaluate the suitability of nitrenium ions and trivalent boron ligands as analogues of N-heterocyclic carbenes in ruthenium-based metathesis catalysts. We ...demonstrate that these analogues induce only minor structural changes in Hoveyda-Grubbs-like precatalysts, but have major impact on precatalyst initiation. Nitrenium ion-modified precatalysts are characterized by a weak Ru-N bond resulting in a relatively strong Ru-O bond and large free energy barriers for initiation, making them good candidates for efficient latent Ru-based catalysts. On the other hand the trivalent boron ligand, bearing a formal -1 charge, binds strongly to the ruthenium ion, weakening the Ru-O bond and facilitating its dissociation, to promote fast reaction initiation. We show that the calculated bond dissociation energy of the Ru-C/N/B bond may serve as an accurate indicator of the Ru-O bond strength and the rate of metathesis initiation.
Pyridoxaboroles - fused heterocyclic systems composed of pyridine and five-membered oxaborole rings - have been obtained for the first time from simple halopyridines. Thus, ...6-butyl-2-(3'-bromo-4'-pyridyl)-(N-B)-1,3,6,2-dioxazaborocan obtained from 3-bromopyridine was converted into a lithio derivative by Br/Li exchange using nBuLi/THF at -85 °C. This intermediate was trapped with benzaldehydes to give the corresponding pyridoxaboroles after hydrolysis. The use of chlorodiphenylsilane as an electrophile gave rise to a related pyridosiloxaborole. The fluorinated pyridoxaborole was obtained by deprotonation of α-(2-methoxyphenyl)-2-fluoro-4-iodopyridylmethanol with NaH and consecutive iodine-lithium exchange/boronation followed by hydrolysis. Single-crystal X-ray analysis of pyridino4,3-c-1,3-dihydro-1-hydroxy-3-mesityl2,1oxaborole revealed the formation of a unique 1D coordination polymer based on N-B dative bonds between monomeric molecules. In contrast, the crystal structure of 2-fluoropyridino4,3-c-1,3-dihydro-1-hydroxy-3-(2'-methoxyphenyl)2,1oxaborole features an infinite H-bonded chain as the main structural motif. The presented considerations are quantified in terms of various computational methods (single molecule and dimer energy calculations, electron density topology, NBO analyses) providing a comprehensive picture of the structural properties of pyridoxaboroles.
The paper deals with the cholesterol–cyclosporine A (Chol–CsA) monolayers at the air/water interface investigated using the Langmuir trough coupled with the Brewster’s angle microscopy. The ...compressed films were transferred onto the PEEK polymer support by means of the Langmuir–Blodgett technique. To improve molecules adhesion and organization the PEEK surface was treated with air plasma before thin films deposition. The obtained surfaces were characterized by means of atomic force microscope (AFM). Then, the wettability of the supported monolayers was determined by the contact angle measurements. Finally, the surface free energy and its components were evaluated from the theoretical approach proposed by van Oss et al. The obtained results reveal correlation between properties of the Langmuir monolayers at the air/water interface and those of the Langmuir–Blodgett films on PEEK. This was found to be helpful for understanding the wettability of organized molecular films on the polymer support as far as biocompatibility improve is concerned. The preparation of films with defined polarity and various compositions is an important step in the development of polymer surfaces with increased biofunctionality. It is believed that the results presented in this paper can be exploited in the in vivo studies.
Single-molecule FRET measures bends and kinks in DNA Woźniak, Anna K; Schröder, Gunnar F; Grubmüller, Helmut ...
Proceedings of the National Academy of Sciences - PNAS,
11/2008, Letnik:
105, Številka:
47
Journal Article
Recenzirano
Odprti dostop
We present advances in the use of single-molecule FRET measurements with flexibly linked dyes to derive full 3D structures of DNA constructs based on absolute distances. The resolution obtained by ...this single-molecule approach harbours the potential to study in detail also protein- or damage-induced DNA bending. If one is to generate a geometric structural model, distances between fixed positions are needed. These are usually not experimentally accessible because of unknown fluorophore-linker mobility effects that lead to a distribution of FRET efficiencies and distances. To solve this problem, we performed studies on DNA double-helices by systematically varying donor acceptor distances from 2 to 10 nm. Analysis of dye-dye quenching and fluorescence anisotropy measurements reveal slow positional and fast orientational fluorophore dynamics, that results in an isotropic average of the FRET efficiency. We use a nonlinear conversion function based on MD simulations that allows us to include this effect in the calculation of absolute FRET distances. To obtain unique structures, we performed a quantitative statistical analysis for the conformational search in full space based on triangulation, which uses the known helical nucleic acid features. Our higher accuracy allowed the detection of sequence-dependent DNA bending by 16°. For DNA with bulged adenosines, we also quantified the kink angles introduced by the insertion of 1, 3 and 5 bases to be 32° ± 6°, 56° ± 4° and 73 ± 2°, respectively. Moreover, the rotation angles and shifts of the helices were calculated to describe the relative orientation of the two arms in detail.
The synthesis and characterization of two novel 6-ethynyl-7-halogen substituted benzosiloxaboroles (Hal = F, Cl) is reported. The crystal structures of these compounds show a unique type of ...supramolecular assembly dictated by distinctive C(π) B interactions resulting in the formation of columnar networks involving alternating ethynyl groups and boron atoms. The QTAIM, NBO and NCI analyses were performed in order to obtain a deeper quantitative insight into the nature of these interactions including energy and charge density distribution. The fluoro derivative
1c
was used as a starting material in Cu-catalyzed 1,3-dipolar cycloaddition reactions with substituted benzenesulfonyl azides giving rise to benzosiloxaboroles with pendant 1-(arylsulfonyl)-1,2,3-triazole-4-yl functionalities or analogous ionic species,
i.e.
, 1,2,3-triazolium arylsulfonates. Screening of antimicrobial activity of obtained derivatives against a wide selection of Gram-positive and Gram-negative bacteria as well as fungi strains was performed and the obtained results were compared with the data obtained previously for related benzosiloxaborole derivatives.
Ethynyl-substituted benzosiloxaboroles feature distinctive C(π) B interactions in the crystalline state and are useful in Cu(
i
)-catalyzed 1,3-dipolar cycloaddition reactions.
We present measurements of the pseudorapidity distribution of primary charged particles produced in Au+Au collisions at three energies, sqrts(NN)=19.6, 130, and 200 GeV, for a range of collision ...centrali-ties. The distribution narrows for more central collisions and excess particles are produced at high pseudorapidity in peripheral collisions. For a given centrality, however, the distributions are found to scale with energy according to the "limiting fragmentation" hypothesis. The universal fragmentation region described by this scaling grows in pseudorapidity with increasing collision energy, extending well away from the beam rapidity and covering more than half of the pseudorapidity range over which particles are produced. This approach to a universal limiting curve appears to be a dominant feature of the pseudorapidity distribution and therefore of the total particle production in these collisions.
The authors present cases of natural death due to arterial or cardiac hemorrhage evaluated using both conventional autopsy examination and post-mortem imaging, including post-mortem computed ...tomography angiography (PMCTA). Visualization based on CT scan acquisition are presented combined with the results of macroscopic and microscopic examination. Based on cases presented it can be seen that in selected cases PMCTA might be a sufficient method of examination while combined with conventional external examination and toxicological investigation; however, in investigations of alleged medical malpractice cases, histopathological examination of specimens seems to be necessary. There are no doubts that post-mortem imaging differs from clinical examination. As we consider the history and the output of clinical imaging methods, there are plenty of challenges awaiting in the field of post-mortem imaging.
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