Search results for " concentration"
showing 10 items of 1684 documents
Resistance to diverse apoptotic triggers in multidrug resistant HL60 cells and its possible relationship to the expression of P-glycoprotein, Fas and…
2002
We studied the human HL60 leukemia cell line and its multidrug resistant (MDR) variant HL60R. In contrast to the HL60, HL60R showed an inability to undergo apoptosis from doxorubicin (Dox) or other different stimuli, including cisplatin, Fas ligation and serum withdrawal. HL60R cells lost surface Fas expression, but we found no evidence that Fas/FasL mediates the apoptotic effects of Dox in HL60. P-glycoprotein (P-gp) did not seem to play a major role as a specific inhibitor of apoptosis. In fact, the P-gp inhibitor verapamil reversed only partially the resistance to Dox-induced apoptosis of the MDR cells. In addition, it did not modify the rate of apoptosis induced from the other stimuli i…
Role of the tumor microenvironment in the activity and expression of the p-glycoprotein in human colon carcinoma cells.
2006
The metabolic microenvironment of solid tumors is characterized by an oxygen deficiency and increased anaerobic glycolysis leading to extracellular acidosis and ATP depletion, which in turn may affect other energy-dependent cellular pathways. Since many tumors overexpress active drug transporters (e.g. the p-glycoprotein) leading to a multidrug-resistant phenotype, this study analyzes the impact of the different aspects of the extracellular microenvironment (hypoxia and acidosis) on the activity and expression of the p-glycoprotein (pGP) in the human colon carcinoma cell line LS513. For up to 24 h cells were exposed to hypoxia (pO2<0.5 mmHg), an acidic extracellular environment (pH 6.6), or…
Genome-wide association analyses identify 18 new loci associated with serum urate concentrations
2013
Elevated serum urate concentrations can cause gout, a prevalent and painful inflammatory arthritis. By combining data from >140,000 individuals of European ancestry within the Global Urate Genetics Consortium (GUGC), we identified and replicated 28 genome-wide significant loci in association with serum urate concentrations (18 new regions in or near TRIM46, INHBB, SFMBT1, TMEM171, VEGFA, BAZ1B, PRKAG2, STC1, HNF4G, A1CF, ATXN2, UBE2Q2, IGF1R, NFAT5, MAF, HLF, ACVR1B-ACVRL1 and B3GNT4). Associations for many of the loci were of similar magnitude in individuals of non-European ancestry. We further characterized these loci for associations with gout, transcript expression and the fractional…
Pharmacogenomics of Cameroonian traditional herbal medicine for cancer therapy
2011
Abstract Ethnopharmacological relevance A socio-economic burden associated with cancers is reported in Africa. Ethnopharmacological usages such as immune and skin disorders, inflammatory, and others chould be considered when selecting plants used to treat cancer, since these reflect disease states bearing relevance to cancer or a cancer symptoms. Materials and methods Documented compounds of Cameroonian medicinal plants were used as keywords in the National Cancer Institute (NCI) database to establish a library of cytotoxic compounds. Cellular and pharmacogenomic profiling was then performed for the 10 most cytotoxic natural products. By COMPARE and hierarchical cluster analyses, candidate …
Identification of Potential Distinguishing Markers for the Use of Cannabis-Based Medicines or Street Cannabis in Serum Samples
2021
Increasing prescription numbers of cannabis-based medicines raise the question of whether uptake of these medicines can be distinguished from recreational cannabis use. In this pilot study, serum cannabinoid profiles after use of cannabis-based medicines were investigated, in order to identify potential distinguishing markers. Serum samples after use of Sativex®, Dronabinol or medical cannabis were collected and analyzed for 18 different cannabinoids, using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Analytes included delta-9-tetrahydrocannabinol, 11-hydroxy-tetrahydrocannabinol, 11-nor-9-carboxy-tetrahydrocannabinol, cannabidiol, cannabinol, cannabigerol, …
Thermodynamic analysis of binding between drugs and glycosaminoglycans by isothermal titration calorimetry and fluorescence spectroscopy
2007
The thermodynamics of the interaction of positively charged drug molecules with negatively charged glycosaminoglycans (GAGs) is investigated by isothermal titration calorimetry (ITC) and fluorescence spectroscopy. The drugs considered are propranolol hydrochloride, tacrine, and aminacrine, and the polymers used as model GAGs are dextran sulfate, chondroitin sulfate, and hyaluronic acid. The ITC results show that the interaction between drugs and GAGs is via direct binding and that GAGs bind to drugs at one set of sites. Large negative values of heat capacity change (DeltaC(p)) are observed upon binding of GAGs to drugs. Such negative DeltaC(p) is not expected for purely electrostatic intera…
Origin and significance of the production of carbon dioxide during the ozonization of 13C-labeled D-glucose at different pH values.
2001
Abstract [1- 13 C], [2- 13 C] and [6- 13 C] d -glucose were, respectively, ozonized in a semi-batch reactor in acidic and basic conditions. The composition of the gas phase was evaluated by on-line mass spectrometry measurements. The quantitative and isotopic analyses of the carbon dioxide formed during ozonization are presented and discussed. The data, correlated with previous literature results, clearly show that at pH 2.5 the production of carbon dioxide from C-6 and C-1 carbon atoms is nearly equivalent. Conversely, at higher pH values, CO 2 is released with a greater selectivity from the reducing end. The importance of the decarboxylation reaction in the formation of by-products with f…
Reconstitution of bacteriorhodopsin and ATP synthase from Micrococcus luteus into liposomes of the purified main tetraether lipid from Thermoplasma a…
1995
The archaebacterium Thermoplasma acidophilum is cultivated at 59 degrees C in a medium containing sulfuric acid of pH 2. The purified bipolar membrane spanning main phospholipid (MPL) of this organism can be used to produce stable liposomes of 100-500 nm in diameter either using a French pressure cell detergent dialysis or sonication. Despite a potassium diffusion potential of 186 mV very low ionic permeability of sonicated MPL liposomes was measured using the potassium binding fluorescent indicator benzofuran isophthalate PBF1, which measures net K+ uptake. The latter also remained very low, in the presence of the K(+) ionophore valinomycin and palmitic acid. Addition of valinomycin and th…
The proteome and transcriptome analysis ofBacillus subtilis in response to salicylic acid
2007
Phenolic acids that are present in plant-soil ecosystems can be considered as toxins which induce specific stress responses in microorganisms. In this paper, we have analyzed the global response of the soil bacterium Bacillus subtilis to salicylic acid using proteomics and transcriptomics. The results demonstrate that salicylic acid caused predominantly the induction of the SigmaB-dependent general stress response in B. subtilis which is not related to the acidic conditions. Treatment of B. subtilis with growth-inhibitory concentrations of 4 mM salicylic acid caused protein damage in B. subtilis as reflected by the induction of the CtsR and Spx regulons. Both phenolic acid decarboxylases (p…
Knockout of thep-Coumarate Decarboxylase Gene fromLactobacillus plantarumReveals the Existence of Two Other Inducible Enzymatic Activities Involved i…
2000
ABSTRACTLactobacillus plantarumNC8 contains apdcgene coding forp-coumaric acid decarboxylase activity (PDC). A food grade mutant, designated LPD1, in which the chromosomalpdcgene was replaced with the deletedpdcgene copy, was obtained by a two-step homologous recombination process using an unstable replicative vector. The LPD1 mutant strain remained able to weakly metabolizep-coumaric and ferulic acids into vinyl derivatives or into substituted phenyl propionic acids. We have shown thatL. plantarumhas a second acid phenol decarboxylase enzyme, better induced with ferulic acid than withp-coumaric acid, which also displays inducible acid phenol reductase activity that is mostly active when gl…