Search results for "membrane permeability"
showing 10 items of 134 documents
Biochemical approach on the conservation of drug molecules during hair fiber formation
1997
A biochemical concept for the endogenous incorporation of drug molecules into growing hair is presented. It is based on the principles of transport across biomembranes, on the principles of biotransformation and drug melanin affinity. The approach gives explanations for current observations in hair analysis, which up to date have not been understood sufficiently. Phenomena such as the ratio of parent drug to metabolite in hair, the dependence of incorporation on the physico-chemical properties of the drug, the independence of drug incorporation on active melanogenesis (incorporation into non-pigmented hair) as well as the dependence of drug content on hair pigmentation are elucidated.
Biopartitioning micellar separation methods: modelling drug absorption
2003
The search for new pharmacologically active compounds in drug discovery programmes often neglects biopharmaceutical properties as drug absorption. As a result, poor biopharmaceutical characteristics constitute a major reason for the low success rate for candidates in clinical development. Since the cost of drug development is many times larger than the cost of drug discovery, predictive methodologies aiding the selection of bioavailable drug candidates are of profound significance. This paper has been focussed on recent developments and applications of chromatographic systems, particularly those systems based on amphiphilic structures, in the frame of alternative approaches for estimating t…
Development of a Multiparametric Cell-based Protocol to Screen and Classify the Hepatotoxicity Potential of Drugs
2012
Hepatotoxicity is a major reason for drug nonapprovals and withdrawals. The multiparametric analysis of xenobiotic toxicity at the single cells level using flow cytometry and cellular imaging-based approaches, such as high-content screening (HCS) technology, could play a key role in the detection of toxicity and the classification of compounds based on patterns of cellular injury. This study aimed to develop and validate a practical, reproducible, in vitro multiparametric cell-based protocol to assess those drugs that are potentially hepatotoxic to humans and to suggest their mechanisms of action. The assay was applied to HepG2 human cell line cultured in 96-well plates and exposed to 78 di…
Sequential biological and photocatalysis based treatments for shipboard slop purification: A pilot plant investigation
2019
This study investigated the treatment of a shipboard slop containing commercial gasoline in a pilot plant scale consisting of a membrane biological reactor (MBR) and photocatalytic reactor (PCR) acting in series. The MBR contributed for approximately 70% to the overall slop purification. More precisely, the biological process was able to remove approximately 40%, on average, of the organic pollution in the slop. Nevertheless, the membrane was capable to retain a large amount of organic molecules within the system, amounting for a further 30% of the influent total organic content removal. However, this affected the membrane fouling, thus resulting in the increase of the pore blocking mechani…
Presystemic metabolism and intestinal absorption of antipsoriatic fumaric acid esters.
2003
Psoriasis is a chronic inflammatory skin disease. Its treatment is based on the inhibition of proliferation of epidermal cells and interference in the inflammatory process. A new systemic antipsoriasis drug, which consists of dimethylfumarate and ethylhydrogenfumarate in the form of their calcium, magnesium and zinc salts has been introduced in Europe with successful results. In the present study, a homologous series of mono- and diesters of fumaric acid has been studied with respect to the sites and kinetics of presystemic ester degradation using pancreas extract, intestinal perfusate, intestinal homogenate and liver S9 fraction. In addition, intestinal permeability has been determined usi…
Utilization of glycerol during consecutive cycles of Lactobacillus reuteri fermentation under pressure: The impact on cell growth and fermentation pr…
2018
Abstract Exposure of bacterial cells to sub-lethal high pressure (HP) during growth and fermentation may promote development of new adaptive features, with potential biotechnological interest. The present work evaluated the effect of consecutive fermentation cycles under HP on Lactobacillus reuteri growth and glycerol/glucose co-fermentation. At all conditions tested (0.1, 10 and 25 MPa), 1,3-propanediol production from glycerol was enhanced over the cycles. The highest titers, yields and productivities were achieved at 10 MPa. In addition, the HP-cycles promoted shifts in by-product formation (ethanol, acetate and lactate), with different profiles according to the pressure. Ratios between …
The inhibition of glycerol permeation through aquaglyceroporin-3 induced by mercury(II)
2016
Mercurial compounds are known to inhibit water permeation through aquaporins (AQPs). Although in the last years some hypotheses were proposed, the exact mechanism of inhibition is still an open question and even less is known about the inhibition of the glycerol permeation through aquaglyceroporins. Molecular dynamics (MD) simulations of human aquaporin-3 (AQP3) have been performed up to 200 ns in the presence of Hg2+ ions. For the first time, we have observed the unbiased passage of a glycerol molecule from the extracellular to cytosolic side. Moreover, the presence of Hg2+ ions covalently bound to Cys40 leads to a collapse of the aromatic/arginine selectivity filter (ar/R SF), blocking th…
Activation of a caspase-3-independent mode of cell death associated with lysosomal destabilization in cultured human retinal pigment epithelial cells…
2008
International audience; Purpose: To characterize the possible cytotoxic effects of oxysterols (7-hydroxycholesterol (7-OH), 25-hydroxycholesterol (25-OH)) in human retinal pigment epithelial cells (ARPE-19) and to detail the relationships between some of these effects. Methods: ARPE-19 cells were treated with 7-OH and 25-OH. Cell viability was measured with the MTT assay. Membrane permeability, mitochondrial potential, and lysosomal integrity were measured by flow cytometry with propidium iodide, DiOC6(3), and acridine orange, respectively. Cell death was characterized by staining with Hoechst 33342, transmission electron microscopy, and analysis of the DNA fragmentation pattern. Caspase ac…
Management of Listeria monocytogenes on Surfaces via Relative Air Humidity: Key Role of Cell Envelope
2021
International audience; Although relative air humidity (RH) strongly influences microbial survival, its use for fighting surface pathogens in the food industry has been inadequately considered. We asked whether RH control could destroy Listeria monocytogenes EGDe by envelope damage. The impact of dehydration in phosphate-buffered saline (PBS) at 75%, 68%, 43% and 11% RH on the bacterial envelope was investigated using flow cytometry and atomic force microscopy. Changes after rehydration in the protein secondary structure and peptidoglycan were investigated by infrared spectroscopy. Complementary cultivability measurements were performed by running dehydration–rehydration with combinations o…
Preventive and post-infection control ofBotrytis cinereain tomato plants by hexanoic acid
2008
The antifungal activity of hexanoic acid on the phytopathogen Botrytis cinerea was studied. This chemical inhibited both spore germination and mycelial growth in vitro in a concentration- and pH-dependent manner, and stopped spore germination at a very early stage, preventing germ-tube development. The minimum fungicidal concentration (MFC) for in vitro spore germination was 16 m m . Hexanoic acid also inhibited in vitro mycelial growth of germinated spores at an MFC of 12 m m . Studies performed to characterize the mechanisms underlying the antimicrobial effect of hexanoic acid showed that it alters fungal membrane permeability. In addition, hexanoic acid treatment increased the levels of …