Search results for "Organic Chemicals"
showing 10 items of 728 documents
Factors influencing structural heat-induced structural relaxation of dissolved organic matter
2018
Abstract Physical and chemical structure affect properties of dissolved organic matter (DOM). Recent observations revealed that heating and cooling cycles at higher temperature amplitude lead to a change in DOM physical conformation assumingly followed by a slow structural relaxation. In this study, changes at lower temperature amplitudes and their relation to DOM composition were investigated using simultaneous measurements of density and ultrasonic velocity in order to evaluate the adiabatic compressibility, which is sensitive indicator of DOM structural microelasticity. Six fulvic acids (FAs) having various origins were analyzed at concentrations of 0.12, 0.6 and 1.2 g L−1 and at differe…
All-trans retinoic acid for treatment of chronic hepatitis C
2008
Background/Aims: In vitro studies in the subgenomic hepatitis C virus (HCV) replicon system have identified all-trans retinoic acid (ATRA) as a potential therapeutic against hepatitis C. Thus, the antiviral potential of this drug should be assessed in vivo. Methods: Twenty highly treatment experienced serotype 1 patients with non-response to conventional or pegylated interferon-α (Peg-/IFN-α) and ribavirin were randomly assigned to 12 weeks of monotherapy with ATRA (group A) or a combination of ATRA and PegIFN-α2a (group B). HCV RNA was assessed by bDNA assay and if negative by highly sensitive polymerase chain reaction. Results: During treatment, five of 10 patients in group A had a drop o…
Inhibitory effect of resveratrol on the proliferation of human and rat hepatic derived cell lines.
2000
Resveratrol is a polyphenolic compound especially produced by grapevine and consequently found in wine. Based on epidemiological studies resveratrol may act as a cancer chemopreventive compound. The ability of resveratrol to inhibit cell proliferation was studied in rat hepatoma Fao cell line and human hepatoblastoma HepG2 cell line. The results show that resveratrol strongly inhibits cell proliferation at the micromolar range in a time- and dose-dependent manner. Concentrations higher than 50 microM become toxic. Fao cells are more sensitive than HepG2 cells. Interestingly, the presence of ethanol lowers the threshold of resveratrol effect. Resveratrol appears to prevent or to delay the en…
Suspected-screening assessment of the occurrence of organic compounds in sewage sludge
2021
The profiling of emerging organic pollutants present in sludge and generated during wastewater treatment is much more limited than in water. This is mainly due to the difficulty of sludge analysis because of its high content of organic matter and interfering compounds. In this study, a generic extraction method using a mixture of buffered water (pH 4.1) and solid phase extraction (SPE) clean-up was applied to samples of sludge obtained in different treatment plants. This extraction was followed by determination of the contaminants by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS), using suspected screening to detect the most relevant o…
Application of accelerated solvent extraction followed by gel performance chromatography and high-performance liquid chromatography for the determina…
2005
Accelerated solvent extraction (ASE) has been evaluated as a fast alternative to methanolic saponification for the extraction of 12 polycyclic aromatic hydrocarbons (PAHs) from mussel tissue. Several solvent systems and different operating conditions were investigated. The mixture dichloromethane-acetone (1:1, v/v) gave the best recoveries at 125 degrees C and 1500 psi, in a total time of 10 min. No yield difference was found between freeze-drying (Fd) or drying the wet mussel with diatomaceous earth (Ded) prior to extraction. The ASE method was validated using the standard reference material SRM 2977, a freeze-dried mussel tissue with naturally present organic contaminants. The performance…
Induction of alkaloid diversity in hybrid plant cell cultures
1999
The treatment of Rauwolfia serpentina x Rhazya stricta somatic hybrid cell suspension culture with 100 μM of methyl jasmonate led to a general increase in indole alkaloid content and to qualitative changes in the alkaloid pattern. The content of Six alkaloids were investigated with respect to their content in both the cell biomass and nutrition medium. Intracellular 17-O-acetyl-norajmaline content on the 5th day after treatment had increased about 40-fold compared with the control culture. The respective concentrations of the other alkaloids increased by a factor of two to five. In total 26 indole alkaloids were identified in extracts of the methyl jasmonate-treated culture by TLC, UV, MS a…
The oxygen-responsive transcriptional regulator FNR ofEscherichia coli : the search for signals and reactions
1997
The FNR (fumarate and nitrate reductase regulation) protein of Escherichia coli is an oxygen-responsive transcriptional regulator required for the switch from aerobic to anaerobic metabolism. In the absence of oxygen, FNR changes from the inactive to the active state. The sensory and the regulatory functions reside in separate domains of FNR. The sensory domain contains a Fe-S cluster, which is of the [4Fe-4S]2+ type under anaerobic conditions. It is suggested that oxygen is supplied to the cytoplasmic FNR by diffusion and inactivates FNR by direct interaction. Reactivation under anoxic conditions requires cellular reductants. In vitro, the Fe-S cluster is converted to a [3Fe-4S]+ or a [2Fe…
What is new for an old molecule? : Systematic review and recommendations on the use of resveratrol
2011
BackgroundResveratrol is a natural compound suggested to have beneficial health effects. However, people are consuming resveratrol for this reason without having the adequate scientific evidence for its effects in humans. Therefore, scientific valid recommendations concerning the human intake of resveratrol based on available published scientific data are necessary. Such recommendations were formulated after the Resveratrol 2010 conference, held in September 2010 in Helsingør, Denmark.MethodologyLiterature search in databases as PUBMED and ISI Web of Science in combination with manual search was used to answer the following five questions: (1)Can resveratrol be recommended in the prevention…
Development of an lbuprofen-Releasing Biodegradable PLA/PGA Electrospun Scaffold for Tissue Regeneration
2009
Our aim was to develop a biodegradable fibrous dressing to act as a tissue guide for in situ wound repair while releasing Ibuprofen to reduce inflammation in wounds and reduce pain for patients on dressing changes. Dissolving the acid form of Ibuprofen (from 1% to 10% by weight) in the same solvent as 75% polylactide, 25% polyglycolide (PLGA) polymers gave uniformly loaded electrospun fibers which gave rapid release of drug within the first 8 h and then slower release over several days. Scaffolds with 10% Ibuprofen degraded within 6 days. The Ibuprofen released from these scaffolds significantly reduced the response of fibroblasts to major pro-inflammatory stimulators. Fibroblast attachment…
The Neuronal Nitric Oxide Synthase Is Upregulated in Mouse Skin Repair and in Response to Epidermal Growth Factor in Human HaCaT Keratinocytes
2004
Expression of nNOS mRNA was found in normal human and mouse skin tissue. Upon wounding, we observed a rapid downregulation of nNOS mRNA and protein in wounds of mice; however, when repair continued, nNOS mRNA was strongly upregulated and nNOS protein expression peaked at late stages of healing. Immunohistochemistry revealed wound keratinocytes as the cellular source of nNOS. In line with the in vivo situation, we found a basal expression of nNOS in the human keratinocyte cell line HaCaT. A marked stimulation of nNOS expression in the cells was achieved with epidermal growth factor receptor (EGFR) ligands such as epidermal growth factor (EGF), heparin-binding EGF, transforming growth factor-…