Search results for "Benzene"
showing 10 items of 1701 documents
Triazolopyridines 20. Hydrogenation reactions
1999
Abstract Hydrogenation reactions of some [1,2,3]triazolo[1,5-a]pyridines and their benzo derivatives, [1,2,3]-triazolo[1,5-a]quinoline and [1,2,3]triazolo[5,1-a]isoquinoline are studied. In general, the pyridine ring is more easily hydrogenated than the triazole or benzene rings.
Hexasubstituted Benzenes with Ultrastrong Dipole Moments
2015
Hexasubstituted benzenes have been synthesized with the highest known dipole moments, as determined by dielectric spectroscopy and DFT methods. Based on the preparation of 4,5-diamino-3,6-dibromophthalonitrile, combined with a novel method to synthesize dihydrobenzimidazoles, these benzene derivatives have dipole moments in excess of 10 debye. Such dipole moments are desirable in ferroelectrics, nonlinear optics, and in organic photovoltaics. Structure determination was achieved through single-crystal X-ray crystallography, and the optical properties were determined by UV/Vis absorption and fluorescence spectroscopy.
Signals involved in the early TH1/TH2 polarization of an immune response depending on the type of antigen.
1999
Abstract Background: The early production of distinct cytokines by epidermal cells (ECs) in response to antigen exposure may govern the development of T H1 -like immune responses, such as contact sensitivity, or T H2 -like immune responses, such as IgE-dependent allergies of the immediate type, depending on the type of antigen. Objective: The aim of this study was to compare the signals induced by protein allergens with those induced by haptens in ECs and subsequently in local draining lymph node cells (LNCs) or splenocytes. Methods: BALB/c mice were primed in vivo with the protein allergens ovalbumin or birch pollen or the haptens 2,4-dinitrofluorobenzene or trinitrochlorbenzene, respectiv…
Multiple activation pathways of benzene leading to products with varying genotoxic characteristics.
1989
Abstract Benzene and 13 potential metabolites were investigated for genotoxicity in Salmonella typhimurium and V79 Chinese hamster cells. In the presence of NADPH-fortified hepatic postmitochondrial fraction (S9 mix), benzene reverted his- S. typhimurium strains. The effect was strongest in strain TA1535. Among the potential metabolites, only the trans-1,2-dihydrodiol, in the presence of S9 mix, and the diol epoxides, in the presence and absence of S9 mix, proved mutagenic in this strain. The anti-diol epoxide was more potent than the syn-diastereomer. Both enantiomers of the anti-diastereomer showed similar activities. S9 mix did not appreciably affect the mutagenicity of the anti-diol epo…
Predominant pathogenic role of tumor necrosis factor in experimental colitis in mice
1997
Antibodies to tumor necrosis factor (TNF)-alpha have been recently proposed as effective treatment for patients with Crohn's disease. Here, we analyze the functional role of TNF-alpha in a mouse model of chronic intestinal inflammation induced by the hapten reagent 2,4,6,-trinitrobenzene sulfonic acid (TNBS) that mimics some characteristics of Crohn's disease in humans. Macrophage-enriched lamina propria (LP) mononuclear cells from mice with TNBS-induced colitis produced 10-30-fold higher levels of TNF-alpha mRNA and protein than cells from control mice. When mice with chronic colitis were treated by intraperitoneal injection of antibodies to TNF-alpha, an improvement of both the clinical a…
Transcript profiling identifies novel key players mediating the growth inhibitory effect of NS-398 on human pancreatic cancer cells
2010
Pancreatic cancer is one of the most aggressive human malignancies with an increasing incidence worldwide. Despite an increase in the number of systemic treatments available for pancreatic cancer, the impact of therapy on the clinical course of the disease has been modest, underscoring an urgent need for new therapeutic options. Although selective cyclooxygenase-2 inhibitors have been demonstrated to have cancer-preventive effects, the mechanism of their effects is not clearly known. Moreover, there have been no unbiased studies to identify novel molecular targets of NS-398 regarding pancreatic cancer. Here we undertook a gene expression profiling study to identify novel molecular targets m…
Identification of lipophilic pollutants discharged from a Finnish pulp and paper mill.
1998
Lipophilic organic compounds originating from kraft pulping and papermaking were identified by straight gas chromatography/mass spectrometry (GC/MS) analyses. Samples analyzed included a primary clarifier effluent (PE) and a secondary clarifier effluent (SE) from the activated sludge treatment plant of a Finnish ECF-bleached (Elementally Chlorine Free) kraft pulp and paper mill. Liquid-liquid extraction composition of PE was compared with solid phase extraction (SPE) and dialysis of a semipermeable membrane device (SPMD) exposed to PE. Dichloromethane extracts of particulate material isolated from PE, sludges from both the primary and secondary clarifier, a sediment collected in the vicinit…
Exposure to benzene and childhood leukaemia: a pilot case-control study
2013
Objectives Main purpose To evaluate the feasibility of a measurement-based assessment of benzene exposure in case-control studies of paediatric cancer; Additional aims To identify the sources of exposure variability; to assess the performance of two benzene biomarkers; to verify the occurrence of participation bias; to check whether exposures to benzene and to 50 Hz magnetic fields were correlated, and might exert reciprocal confounding effects. Design Pilot case-control study of childhood leukaemia and exposure to benzene assessed by repeated seasonal weekly measurements in breathing zone air samples and outside the children9s dwellings, with concurrent determinations of cotinine, t-t-muco…
SPME of 52 pesticides and polychlorinated biphenyls: Extraction efficiencies of the SPME coatings poly(dimethylsiloxane), polyacrylate, poly(dimethyl…
2001
Fiber/water partition coefficients (Kfw) of 52 pesticides, including triazines, organophosphorus pesticides, organochlorine pesticides, and polychlorinated biphenyls (PCBs) were experimentally calculated for the five polymeric coatings poly(dimethylsiloxane) (PDMS), polyacrylate (PA), poly(dimethylsiloxane)-Divinylbenzene (PDMS-DVB), Carboxen-poly(dimethylsiloxane) (CAR-PDMS), and Carbowax-divinylbenzene (CW-DVB) commercially available for solid-phase microextraction coupled to gas chromatography. The equilibrium-time profiles for the five coatings were previously studied in order to establish the time needed for equilibrium. To calculate Kfw the amount of analyte extracted at equilibrium w…
Molecular Ribbons Containing Pyridine Rings
1996
The first synthesis of the ribbon-like compounds 6–10 is described. The new building block diethyl 2,6-bis(bromomethyl)pyridine-3,5-dicarboxylate 1 was prepared and characterized. Single-crystal X-ray structure analyses indicate that these ribbon-like molecules arrange in a folded conformation, with the pyridine and benzene units being folded in a face-to-face manner, and the tosyl units of 8–10 pointing outwards. The “intramolecular self-assembly” (folding) of these molecular ribbons is primarily attributable to the energetically more favourable syn conformation of both the [3.3]metacyclophanes and the pyridinophanes.