The Experts below are selected from a list of 1104 Experts worldwide ranked by ideXlab platform
Ahmed A Omran - One of the best experts on this subject based on the ideXlab platform.
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equilibrium thermodynamics of the partitioning of non steroidal anti inflammatory drugs into human Erythrocyte Ghost membranes
The Journal of Chemical Thermodynamics, 2013Co-Authors: Ahmed A OmranAbstract:Abstract In this work,second derivative spectrophotometry was applied for determining the partition coefficients ( K p s) of four non-steroidal anti-inflammatory drugs (NSAIDs; flufenamic, meclofenamic, mefenamic and niflumic acids) into human Erythrocyte Ghost (HEG) membranes over a temperature range from (283.2 to 313.2) K. The proposed method allowed the evaluation and direct analyses of thermodynamic parameters; enthalpy (Δ H W → M ), Gibbs energy (Δ G W → M ) and entropy (Δ S W → M ) changes of the partitioning of NSAIDs into HEG membranes. The partitioning of NSAIDs between polar aqueous phase and non-polar lipid bilayer HEG membrane phase was exothermic with negative (Δ H W → M ) which compensated for the changes in (Δ S W → M ). The negative values of (Δ G W → M ) revealed that the partitioning of NSAIDs into HEG, owing to their transfer from polar aqueous phase and non-polar HEG phase is spontaneous. The enthalpy–entropy correlation analysis resulted in a good linearity that suggests an identical partitioning enthalpy–entropy driven compensation mechanism for the studied NSAIDs.
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an in vitro spectrometric method for determining the partition coefficients of non steroidal anti inflammatory drugs into human Erythrocyte Ghost membranes
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013Co-Authors: Ahmed A OmranAbstract:Abstract Usefulness of second derivative spectrophotometry for determining the partition coefficients ( K p s ) of four non-steroidal anti-inflammatory drugs (NSAIDs) between human Erythrocyte Ghost (HEG) membranes and buffer at simulated physiological conditions (pH = 7.4, 37 °C) has been adequately emphasized. In the absorption spectra for each of the investigated NSAIDs, λ max was red-shifted in presence of HEG membranes, indicating that NSAIDs have the nature of metachromasy between lipid bilayer and water. Further quantitative spectral data for calculating K p s could not be obtained from the absorption spectra because of the presence of background signal impacts of HEG lipid bilayers. Second derivative spectra were calculated from absorption spectra and fortunately showed three isosbestic derivative points for each NSAID, indicating without doubt that the background signals were entirely eliminated. From the relation between the derivative intensity change (Δ D ) induced by addition of HEG membranes, K p s were calculated and obtained with RSD of below 6%. Fractions of partitioned NSAIDs are in well-harmony with that derived from the experimental values. Moreover, validity of the proposed method was confirmed. Conclusively, the second derivative spectrometry has proven to be a facile, reliable and more expeditious method to obtain in vitro K p s of drugs to HEG without previous separation.
Benedikt M Kessler - One of the best experts on this subject based on the ideXlab platform.
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a robust mass spectrometry method for rapid profiling of Erythrocyte Ghost membrane proteomes
Clinical Proteomics, 2018Co-Authors: Haddy K S Fye, Paul Mrosso, Lesley J Bruce, Marielaetitia Thezenas, Simon J Davis, Roman Fischer, Gration Rwegasira, Julie Makani, Benedikt M KesslerAbstract:Red blood cell (RBC) physiology is directly linked to many human disorders associated with low tissue oxygen levels or anemia including chronic obstructive pulmonary disease, congenital heart disease, sleep apnea and sickle cell anemia. Parasites such as Plasmodium spp. and phylum Apicomplexa directly target RBCs, and surface molecules within the RBC membrane are critical for pathogen interactions. Proteomics of RBC membrane ‘Ghost’ fractions has therefore been of considerable interest, but protocols described to date are either suboptimal or too extensive to be applicable to a larger set of clinical cohorts. Here, we describe an optimised Erythrocyte isolation protocol from blood, tested for various storage conditions and explored using different fractionation conditions for isolating Ghost RBC membranes. Liquid chromatography mass spectrometry (LC–MS) analysis on a Q-Exactive Orbitrap instrument was used to profile proteins isolated from the comparative conditions. Data analysis was run on the MASCOT and MaxQuant platforms to assess their scope and diversity. The results obtained demonstrate a robust method for membrane enrichment enabling consistent MS based characterisation of > 900 RBC membrane proteins in single LC–MS/MS analyses. Non-detergent based membrane solubilisation methods using the tissue and supernatant fractions of isolated Ghost membranes are shown to offer effective haemoglobin removal as well as diverse recovery including Erythrocyte membrane proteins of high and low abundance. The methods described in this manuscript propose a medium to high throughput framework for membrane proteome profiling by LC–MS of potential applicability to larger clinical cohorts in a variety of disease contexts.
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A robust mass spectrometry method for rapid profiling of Erythrocyte Ghost membrane proteomes
'Springer Science and Business Media LLC', 2018Co-Authors: Haddy K S Fye, Paul Mrosso, Marielaetitia Thezenas, Roman Fischer, Gration Rwegasira, Julie Makani, Lesley Bruce, Simon Davis, Benedikt M KesslerAbstract:Abstract Background Red blood cell (RBC) physiology is directly linked to many human disorders associated with low tissue oxygen levels or anemia including chronic obstructive pulmonary disease, congenital heart disease, sleep apnea and sickle cell anemia. Parasites such as Plasmodium spp. and phylum Apicomplexa directly target RBCs, and surface molecules within the RBC membrane are critical for pathogen interactions. Proteomics of RBC membrane ‘Ghost’ fractions has therefore been of considerable interest, but protocols described to date are either suboptimal or too extensive to be applicable to a larger set of clinical cohorts. Methods Here, we describe an optimised Erythrocyte isolation protocol from blood, tested for various storage conditions and explored using different fractionation conditions for isolating Ghost RBC membranes. Liquid chromatography mass spectrometry (LC–MS) analysis on a Q-Exactive Orbitrap instrument was used to profile proteins isolated from the comparative conditions. Data analysis was run on the MASCOT and MaxQuant platforms to assess their scope and diversity. Results The results obtained demonstrate a robust method for membrane enrichment enabling consistent MS based characterisation of > 900 RBC membrane proteins in single LC–MS/MS analyses. Non-detergent based membrane solubilisation methods using the tissue and supernatant fractions of isolated Ghost membranes are shown to offer effective haemoglobin removal as well as diverse recovery including Erythrocyte membrane proteins of high and low abundance. Conclusions The methods described in this manuscript propose a medium to high throughput framework for membrane proteome profiling by LC–MS of potential applicability to larger clinical cohorts in a variety of disease contexts
Ignacy Gryczynski - One of the best experts on this subject based on the ideXlab platform.
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observation of Erythrocyte dynamics in the retinal capillaries and choriocapillaris using icg loaded Erythrocyte Ghost cells
Investigative Ophthalmology & Visual Science, 2008Co-Authors: Robert W Flower, Enrico Peiretti, Mauro Magnani, Luigia Rossi, Sonja Serafini, Zygmunt Gryczynski, Ignacy GryczynskiAbstract:Purpose To find evidence of retinal vasomotion and to examine the relationship between Erythrocyte dynamics and previously observed high-frequency pulsatile blood flow through the choriocapillaris. Methods An osmotic shock technique was used to encapsulate indocyanine green (ICG) dye in Erythrocyte Ghost cells at a concentration that produced maximum cell fluorescence. By obviating the plasma staining that results from aqueous ICG's high affinity for plasma proteins, high contrast was maintained between reinjected ICG-loaded Erythrocytes and their plasma background. High-speed, high-magnification ICG angiograms showing individual cell movement were recorded from the intact eyes of four monkeys and three rabbits for periods up to 30 seconds. Results In monkey retinal perifoveal capillaries, numerous Erythrocytes were seen to pause for as long as 20 seconds and then resume transit. Similar pausing behavior was observed in the subfoveal choriocapillaris. Individual Erythrocytes also were seen to pause in the rabbits' choriocapillaries below the medullary rays, where visualization of the cells was uninhibited by overlying retinal vasculature or dense pigment. Conclusions Reinjected ICG-loaded Erythrocytes permit routine visualization of retinal capillary and choriocapillaris hemodynamics of the intact eye. It is speculated that Erythrocyte-pausing in both microcirculations facilitates metabolic exchange across capillary walls. In retinal capillaries, pausing is presumed to result from vasomotion-which has been postulated as necessary for the inhibition of retinal edema-and in choriocapillaries, to result from the shifting distributions of local perfusion pressures within the network of capillary vessel segments that comprise each lobular area of the choriocapillaris vascular plexus.
Haddy K S Fye - One of the best experts on this subject based on the ideXlab platform.
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a robust mass spectrometry method for rapid profiling of Erythrocyte Ghost membrane proteomes
Clinical Proteomics, 2018Co-Authors: Haddy K S Fye, Paul Mrosso, Lesley J Bruce, Marielaetitia Thezenas, Simon J Davis, Roman Fischer, Gration Rwegasira, Julie Makani, Benedikt M KesslerAbstract:Red blood cell (RBC) physiology is directly linked to many human disorders associated with low tissue oxygen levels or anemia including chronic obstructive pulmonary disease, congenital heart disease, sleep apnea and sickle cell anemia. Parasites such as Plasmodium spp. and phylum Apicomplexa directly target RBCs, and surface molecules within the RBC membrane are critical for pathogen interactions. Proteomics of RBC membrane ‘Ghost’ fractions has therefore been of considerable interest, but protocols described to date are either suboptimal or too extensive to be applicable to a larger set of clinical cohorts. Here, we describe an optimised Erythrocyte isolation protocol from blood, tested for various storage conditions and explored using different fractionation conditions for isolating Ghost RBC membranes. Liquid chromatography mass spectrometry (LC–MS) analysis on a Q-Exactive Orbitrap instrument was used to profile proteins isolated from the comparative conditions. Data analysis was run on the MASCOT and MaxQuant platforms to assess their scope and diversity. The results obtained demonstrate a robust method for membrane enrichment enabling consistent MS based characterisation of > 900 RBC membrane proteins in single LC–MS/MS analyses. Non-detergent based membrane solubilisation methods using the tissue and supernatant fractions of isolated Ghost membranes are shown to offer effective haemoglobin removal as well as diverse recovery including Erythrocyte membrane proteins of high and low abundance. The methods described in this manuscript propose a medium to high throughput framework for membrane proteome profiling by LC–MS of potential applicability to larger clinical cohorts in a variety of disease contexts.
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A robust mass spectrometry method for rapid profiling of Erythrocyte Ghost membrane proteomes
'Springer Science and Business Media LLC', 2018Co-Authors: Haddy K S Fye, Paul Mrosso, Marielaetitia Thezenas, Roman Fischer, Gration Rwegasira, Julie Makani, Lesley Bruce, Simon Davis, Benedikt M KesslerAbstract:Abstract Background Red blood cell (RBC) physiology is directly linked to many human disorders associated with low tissue oxygen levels or anemia including chronic obstructive pulmonary disease, congenital heart disease, sleep apnea and sickle cell anemia. Parasites such as Plasmodium spp. and phylum Apicomplexa directly target RBCs, and surface molecules within the RBC membrane are critical for pathogen interactions. Proteomics of RBC membrane ‘Ghost’ fractions has therefore been of considerable interest, but protocols described to date are either suboptimal or too extensive to be applicable to a larger set of clinical cohorts. Methods Here, we describe an optimised Erythrocyte isolation protocol from blood, tested for various storage conditions and explored using different fractionation conditions for isolating Ghost RBC membranes. Liquid chromatography mass spectrometry (LC–MS) analysis on a Q-Exactive Orbitrap instrument was used to profile proteins isolated from the comparative conditions. Data analysis was run on the MASCOT and MaxQuant platforms to assess their scope and diversity. Results The results obtained demonstrate a robust method for membrane enrichment enabling consistent MS based characterisation of > 900 RBC membrane proteins in single LC–MS/MS analyses. Non-detergent based membrane solubilisation methods using the tissue and supernatant fractions of isolated Ghost membranes are shown to offer effective haemoglobin removal as well as diverse recovery including Erythrocyte membrane proteins of high and low abundance. Conclusions The methods described in this manuscript propose a medium to high throughput framework for membrane proteome profiling by LC–MS of potential applicability to larger clinical cohorts in a variety of disease contexts
Brian L Silver - One of the best experts on this subject based on the ideXlab platform.
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a simple spectroscopic method for studying Erythrocyte Ghost resealing
Biochimica et Biophysica Acta, 1991Co-Authors: Edith Kahana, Sara Streichman, Brian L SilverAbstract:A novel spectroscopic method is described for following the kinetics of resealing of hemolysed Erythrocyte Ghosts. The procedure is based on the broadening of the EPR spectrum of nitroxyl radicals by paramagnetic ions. The method is used to study the effect of Ca2+, Mg2+ and dimethonium ion on the kinetics of resealing.