scholarly journals Binding of hypoglycaemic sulphonylureas to an artificial phospholipid bilayer

Diabetologia ◽  
1984 ◽  
Vol 26 (1) ◽  
Author(s):  
M. Deleers ◽  
W.J. Malaisse
Keyword(s):  
Phospholipid Bilayer ◽  
Hypoglycaemic Sulphonylureas

Factors Affecting the lnteraction of Tissue Factor/Factor Vll with Factor X in a Heterogeneous Tubular Reactor

1991 ◽  
Vol 65 (02) ◽  
pp. 139-143 ◽  
Author(s):  
Cynthia H Gemmell ◽  
Vincet T Turitto ◽  
Yale Nemerson
Keyword(s):  
Steady State ◽  
Tissue Factor ◽  
Factor Viia ◽  
Transmembrane Protein ◽  
Strong Association ◽  
Tubular Reactor ◽  
Factor Xa ◽  
Phospholipid Bilayer ◽  
Factor Vii ◽  
Factor X

SummaryA novel reactor recently described for studying phospholipiddependent blood coagulation reactions under flow conditions similar to those occurring in the vasculature has been further charactenzed. The reactor is a capitlary whose inner wall is coated with a stable phospholipid bilayer (or two bilayers) containing tissue factor, a transmembrane protein that is required for the enzymatic activation of factor X by factor VIIa. Perfusion of the capillary at wall shear rates ranging from 25 s−1 to 1,200 s−1 with purified bovine factors X and VIIa led to steady state factor Xa levels at the outlet. Assay were performed using a chromogenic substrate, SpectrozymeTMFXa, or by using a radiometric technique. In the absence of Ca2+ or factor VIIa there was no product formation. No difference was noted in the levels of factor Xa achieved when non-activated factor VII was perfused. Once steady state was achieved further factor Xa production continued in the absence of factor VIIa implying a very strong association of factor VIIa with the tissue factor in the phospholipid membrane. In agreement with static vesicle-type studies the reactor was sensitive to wall tissue factor concentration, temperature and the presence of phosphatidylserine in the bilayer.

scholarly journals Evaluation of the correlation between porphyrin accumulation in cancer cells and functional positions for application as a drug carrier

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Koshi Nishida ◽  
Toshifumi Tojo ◽  
Takeshi Kondo ◽  
Makoto Yuasa
Keyword(s):  
Cancer Cells ◽  
Drug Carrier ◽  
Bilayer Membrane ◽  
Phospholipid Bilayer ◽  
Membrane Permeation ◽  
Porphyrin Derivatives ◽  
Phospholipid Bilayer Membrane ◽  
Meso Position ◽  
Tumor Accumulation ◽  
Binding Position

AbstractPorphyrin derivatives accumulate selectively in cancer cells and are can be used as carriers of drugs. Until now, the substituents that bind to porphyrins (mainly at the meso-position) have been actively investigated, but the effect of the functional porphyrin positions (β-, meso-position) on tumor accumulation has not been investigated. Therefore, we investigated the correlation between the functional position of substituents and the accumulation of porphyrins in cancer cells using cancer cells. We found that the meso-derivative showed higher accumulation in cancer cells than the β-derivative, and porphyrins with less bulky substituent actively accumulate in cancer cells. When evaluating the intracellular distribution of porphyrin, we found that porphyrin was internalized by endocytosis and direct membrane permeation. As factors involved in these two permeation mechanisms, we evaluated the affinity between porphyrin-protein (endocytosis) and the permeability to the phospholipid bilayer membrane (direct membrane permeation). We found that the binding position of porphyrin affects the factors involved in the transmembrane permeation mechanisms and impacts the accumulation in cancer cells.

scholarly journals Recent Advancements in Polymer/Liposome Assembly for Drug Delivery: From Surface Modifications to Hybrid Vesicles

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1027
Author(s):  
Vincenzo De Leo ◽  
Francesco Milano ◽  
Angela Agostiano ◽  
Lucia Catucci
Keyword(s):  
Drug Delivery ◽  
First Generation ◽  
Phospholipid Bilayer ◽  
Bioactive Molecules ◽  
Systemic Delivery ◽  
Molecular Weights ◽  
Liposome Preparation ◽  
Wide Range ◽  
Liposome Surface

Liposomes are consolidated and attractive biomimetic nanocarriers widely used in the field of drug delivery. The structural versatility of liposomes has been exploited for the development of various carriers for the topical or systemic delivery of drugs and bioactive molecules, with the possibility of increasing their bioavailability and stability, and modulating and directing their release, while limiting the side effects at the same time. Nevertheless, first-generation vesicles suffer from some limitations including physical instability, short in vivo circulation lifetime, reduced payload, uncontrolled release properties, and low targeting abilities. Therefore, liposome preparation technology soon took advantage of the possibility of improving vesicle performance using both natural and synthetic polymers. Polymers can easily be synthesized in a controlled manner over a wide range of molecular weights and in a low dispersity range. Their properties are widely tunable and therefore allow the low chemical versatility typical of lipids to be overcome. Moreover, depending on their structure, polymers can be used to create a simple covering on the liposome surface or to intercalate in the phospholipid bilayer to give rise to real hybrid structures. This review illustrates the main strategies implemented in the field of polymer/liposome assembly for drug delivery, with a look at the most recent publications without neglecting basic concepts for a simple and complete understanding by the reader.

scholarly journals Development of discoidal phospholipid bilayer nanoparticles with styrene maleic acid copolymer for diagnosis and therapy of intractable cancers

2021 ◽  
Vol 96-97 ◽  
pp. S83
Author(s):  
Masayuki Munekane ◽  
Wakana Yamaguchi ◽  
Kohei Sano ◽  
Toshihide Yamasaki ◽  
Masafumi Tanaka ◽  
...  
Keyword(s):  
Maleic Acid ◽  
Phospholipid Bilayer ◽  
Diagnosis And Therapy ◽  
Acid Copolymer ◽  
Maleic Acid Copolymer

scholarly journals The impact of orally administered gadolinium orthovanadate GdVO4:Eu3+ nanoparticles on the state of phospholipid bilayer of erythrocytes

2020 ◽  
Vol 45 (4) ◽  
pp. 389-395
Author(s):  
Anton Tkachenko ◽  
Anatolii Onishchenko ◽  
Vladimir Klochkov ◽  
Nataliya Kavok ◽  
Oksana Nakonechna ◽  
...  
Keyword(s):  
Fluorescent Probes ◽  
Lipid Membranes ◽  
Chemical Properties ◽  
Proton Donor ◽  
The State ◽  
Phospholipid Bilayer ◽  
Erythrocyte Membranes ◽  
Control Group ◽  
Donor Ability ◽  
The Impact

AbstractObjectivesTo assess the state of phospholipid bilayer of red blood cells (RBCs) in rats orally exposed to gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) during two weeks using fluorescent probes − ortho-hydroxy derivatives of 2,5-diaryl-1,3-oxazole.MethodsSteady-state fluorescence spectroscopy: a study by the environment-sensitive fluorescent probes − 2-(2′-OH-phenyl)-5-phenyl-1,3-oxazole (probe O1O) and 2-(2′-OH-phenyl)-phenanthro[9,10]-1,3-oxazole (probe PH7).ResultsNo significant changes are detected in the spectra of the fluorescent probes bound to the RBCs from the rats orally exposed to nanoparticles in comparison with the corresponding spectra of the probes bound to the cells from the control group of animals. This indicates that, in case of the rats orally exposed to nanoparticles, no noticeable changes in physico-chemical properties (i.e., in the polarity and the proton-donor ability) are observed in the lipid membranes of RBCs in the region, where the probes locate.ConclusionsNo changes in the physical and chemical properties of the erythrocyte membranes are detected in the region from glycerol backbones of phospholipids to the center of the phospholipid bilayer in the rats orally exposed to VNPs during 2 weeks.

P1935Pharmacokinetic and pharmacodynamic assessment of a lipid-based aspirin formulation: results of a prospective, randomised, crossover study

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
D J Angiolillo ◽  
D L Bhatt ◽  
F Lanza ◽  
B Cryer ◽  
J Dong ◽  
...  
Keyword(s):  
Crossover Study ◽  
Safety Profile ◽  
Immediate Release ◽  
Mucosal Injury ◽  
Thromboxane B2 ◽  
Phospholipid Bilayer ◽  
Liquid Formulation ◽  
Parameter Ratio ◽  
Serum Thromboxane ◽  
Parameter Values

Abstract Objectives Aspirin, or acetylsalicylic acid (ASA), can lead to gastrointestinal mucosal injury through disruption of its protective phospholipid bilayer, underscoring the need for ASA formulations with a more favorable safety profile while maintaining an effective pharmacologic profile. A liquid formulation using a novel pharmaceutical lipid aspirin complex (PL-ASA) has been designed to prevent the disruption of the protective mucosal bilayer. We sought to determine the pharmacokinetic (PK)/pharmacodynamic (PD) characteristics of PL-ASA compared with traditional, immediate release aspirin (IR-ASA). Methods In this active-control crossover study, 16 healthy volunteers were randomized to receive a single dose of either IR-ASA 325 mg or PL-ASA 325 mg in a sequential fashion with a 2-week washout period between treatment assignments. The primary objectives of the study were to assess PK (i.e., plasma salicylic acid levels) and PD (i.e., serum thromboxane B2 levels) bioequivalence over a 24–hour period after drug administration, of PL-ASA and IR-ASA using established criteria. Results The PK parameter values were similar for PL-ASA and IR-ASA, with median AUC 0-t and Cmax values nominally higher for PL-ASA. Log-transformed PK parameters meeting FDA-criteria for bioequivalence (80% to 125%) are provided in the Table. Serum thromboxane B2 levels were similar for PL-ASA and IR-ASA, with Cmin values below 3.1 ng/mL (cut-off associated with decreased cardiovascular events) for both drugs. Both drugs also showed >99% inhibition of serum thromboxane B2 levels (≥95% inhibition represents the cut-off to define aspirin responders). Several secondary PK/PD parameters showed similarities between the two drugs (data not shown). Overall, these findings support functional and clinical equivalence between PL-ASA and IR-ASA. PK Results Parameter Ratio (PL-ASA/IR-ASA) 90% Confidence Interval AUC0-t 96.51 89.24, 104.37 Cmax 103.73 92.06, 116.89 Conclusions PL-ASA's novel liquid formulation has similar PK and PD performance compared with IR-ASA. The improved endoscopic safety profile of PL-ASA coupled with its pharmacologic efficacy equivalent to IR-ASA may result in an improved benefit-risk performance, warranting evaluation in future trials. Acknowledgement/Funding PLx Pharma, Inc.

scholarly journals Modulation of phospholipase A2 activity by the tumour promoters phorbol esters and teleocidin

1990 ◽  
Vol 268 (1) ◽  
pp. 169-173 ◽  
Author(s):  
K Y Nam ◽  
A Morino ◽  
S Kimura ◽  
H Fujiki ◽  
Y Imanishi
Keyword(s):  
Phospholipase A2 ◽  
Membrane Structure ◽  
Phorbol Esters ◽  
Hydrolytic Activity ◽  
Phospholipid Bilayer ◽  
Structural Defects ◽  
Moderate Degree ◽  
Pla2 Activity ◽  
Tumour Promoters ◽  
High Concentrations

The effects of tumour promoters, namely phorbol esters and teleocidin, on the activity of porcine pancreatic phospholipase A2 (PLA2) was investigated by using a system of small unilamellar vesicles composed of dipalmitoyl-phosphatidylcholine (DPPC). DPPC vesicles encapsulating Quin 2 (Quin 2/DPPC vesicles) were suspended in a medium containing Ca2+. The addition of PLA2 to Quin 2/DPPC vesicles increased the fluorescence intensity of Quin 2. This increase was due to chelation of Quin 2 with Ca2+, which resulted from an increase in the permeability of the phospholipid bilayer caused by the hydrolytic activity of PLA2. The tumour promoters phorbol 12-myristate 13-acetate (PMA) and teleocidin, at low concentrations, enhanced PLA2 activity at temperatures below the phase-transition temperature of the membrane, but, in contrast, high concentrations of the tumour promoters suppressed PLA2 activity. Phorbol 12-myristate (PM) also had a similar effect on PLA2 activity. PMA and PM disturbed the membrane structure markedly, which was indicated by the enhanced leakage of carboxyfluorescein (CF) from DPPC vesicles encapsulating CF. On the other hand, phorbol 12,13-didecanoate and 4 alpha-phorbol 12,13-didecanoate, which did not disturb the membrane structure to the same extent, had an insignificant effect on PLA2 activity. It is therefore concluded that PLA2 catalyses the hydrolysis of phospholipids in bilayer vesicles which contain a moderate degree of structural defects. However, the effects of tumour promoters on PLA2 activity was not related to their potencies as inflammatory and tumour-promoting agents.

Antimicrobial mode of action of secretions from the metapleural gland ofMytmecia gulosa(Australian bull ant)

1995 ◽  
Vol 41 (2) ◽  
pp. 136-144 ◽  
Author(s):  
J. A. Mackintosh ◽  
J. E. Trimble ◽  
A. J. Beattie ◽  
D. A. Veal ◽  
M. K. Jones ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antimicrobial Agents ◽  
Structural Integrity ◽  
Phospholipid Bilayer ◽  
Active Components ◽  
Cytoplasmic Matrix ◽  
Metapleural Glands ◽  
Total Leakage ◽  
Membrane Bound ◽  
And Function

Secretions from exocrine metapleural glands of Myrmecia gulosa (Australian bull ant) exhibit broad-spectrum antimicrobial activity. Treatment of the yeast Candida albicans with metapleural secretion resulted in the rapid and total leakage of K+ions from cells within 10 min. Ultrastructural analysis of the bacteria Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa, and cells and protoplasts of Candida albicans demonstrated gross damage of the cell membrane and aggregation of the cytoplasmic matrix of treated cells. Degradation of membrane-bound organelles was also observed in Candida albicans. The antimicrobially active components of metapleural secretions were nonpolar and interacted with the phospholipid bilayer, causing damage to the structural integrity of liposomes and the release of carboxyfluorescein. The data suggest that the antimicrobial agents in metapleural secretion act primarily by disrupting the structure and function of the phospholipid bilayer of the cytoplasmic membrane.Key words: ant metapleural secretion, antimicrobial, Candida albicans, cytoplasmic membrane.

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