12 results on '"S. Luik"'
Search Results
2. Human whole blood assay for rapid and routine testing of non-steroidal anti-inflammatory drugs (NSAIDs) on cyclo-oxygenase-2 activity
- Author
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Stefan Laufer, S. Luik, F. Dehner, C. Greim, and Samir S. Ayoub
- Subjects
Glycerol ,Lipopolysaccharides ,Allergy ,Routine testing ,Immunology ,Stimulation ,Pharmacology ,Inhibitory Concentration 50 ,Humans ,Medicine ,Pharmacology (medical) ,Cyclo oxygenase 2 ,Whole blood ,Cyclooxygenase 2 Inhibitors ,Ethanol ,business.industry ,Anti-Inflammatory Agents, Non-Steroidal ,Prostaglandin production ,Reproducibility of Results ,medicine.disease ,Solubility ,Non steroidal anti inflammatory ,Cyclooxygenase 2 ,Biological Assay ,lipids (amino acids, peptides, and proteins) ,Pharmaceutical Vehicles ,Cyclo-oxygenase ,business ,Hydrophobic and Hydrophilic Interactions - Abstract
Aim of this study was to present a simple, fast and reliable method to examine the capacity of NSAIDs to inhibiting COX-2 activity that uses rapid (stimulation takes only 5 h compared to other existing protocols) and routine testing. The assay includes elimination of COX-1-activity using ASS (a selective COX-1 inhibitor) and the thromboxane synthetase inhibitor (TXBSI), COX-2 induction via LPS and measurement of PGE(2). Using TXBSI reduces the amount of LPS and results in higher prostaglandin production. Cremophor EL-EtOH was used as vehicle instead of DMSO because within a defined concentration range, Cremophor EL-EtOH allows even very hydrophobic drugs to be solubilized and applied in vitro without cell damage. Cremophor EL-EtOH at 0.2% was optimal as at this relatively low concentration excellent drug dissolution was obtained whereas many hydrophobic substances precipitate in 0.2% DMSO. Our results demonstrate that the IC(50) values for the tested NSAIDs are in the range of published data.
- Published
- 2008
- Full Text
- View/download PDF
3. Participation of leukotriene C(4) in the regulation of suicidal erythrocyte death
- Author
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M, Foller, H, Mahmud, S, Gu, K, Wang, E, Floride, Y, Kucherenko, S, Luik, S, Laufer, and F, Lang
- Subjects
Receptors, Leukotriene ,Caspase 8 ,Erythrocytes ,Microscopy, Confocal ,Cell Death ,Caspase 3 ,Blotting, Western ,Erythrocyte Membrane ,Cell Culture Techniques ,Phosphatidylserines ,Leukotriene C4 ,Thiazoles ,Glucose ,Humans ,Hydroxyurea ,Calcium ,Cells, Cultured ,Cell Size - Abstract
Eryptosis, the suicidal death of erythrocytes, is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Eryptosis is triggered by increase in cytosolic Ca(2+) concentration upon energy depletion. The present study explored the involvement of leukotrienes. Western blotting was employed to detect the cysteinyl-leukotriene receptor cysLT1, competitive immune assay to determine leukotriene release from erythrocytes, Fluo3 fluorescence to estimate cytosolic Ca(2+) concentration, forward scatter to analyse cell volume and annexin V-binding to disclose phosphatidylserine exposure. As a result, erythrocytes expressed the leukotriene receptor CysLT1. Glucose depletion (24 hours) significantly increased the formation of the cysteinyl-leukotrienes C(4)/D(4)/E(4). Leukotriene C(4) (10 nM) increased Ca(2+) entry, decreased forward scatter, activated caspases 3 and 8, and stimulated annexin V-binding. Glucose depletion similarly increased annexin V-binding, an effect significantly blunted in the presence of the leukotriene receptor antagonist cinalukast (1 microM) or the 5-lipoxygenase inhibitor BW B70C (1 microM). In conclusion, upon energy depletion erythrocytes form leukotrienes, which in turn activate cation channels, leading to Ca(2+) entry, cell shrinkage and cell membrane scrambling. Cysteinyl-leukotrienes thus participate in the signaling of eryptosis during energy depletion.
- Published
- 2008
4. RSV Prefusion F Protein-Based Maternal Vaccine - Preterm Birth and Other Outcomes.
- Author
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Dieussaert I, Hyung Kim J, Luik S, Seidl C, Pu W, Stegmann JU, Swamy GK, Webster P, and Dormitzer PR
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- Female, Humans, Infant, Infant, Newborn, Pregnancy, Respiratory Tract Diseases prevention & control, Respiratory Tract Diseases virology, Vaccine Efficacy, Treatment Outcome, Adolescent, Young Adult, Adult, Middle Aged, Risk, Premature Birth chemically induced, Premature Birth etiology, Respiratory Syncytial Virus Infections prevention & control, Respiratory Syncytial Virus Vaccines administration & dosage, Respiratory Syncytial Virus Vaccines adverse effects, Respiratory Syncytial Virus Vaccines therapeutic use, Respiratory Syncytial Virus, Human
- Abstract
Background: Vaccination against respiratory syncytial virus (RSV) during pregnancy may protect infants from RSV disease. Efficacy and safety data on a candidate RSV prefusion F protein-based maternal vaccine (RSVPreF3-Mat) are needed., Methods: We conducted a phase 3 trial involving pregnant women 18 to 49 years of age to assess the efficacy and safety of RSVPreF3-Mat. The women were randomly assigned in a 2:1 ratio to receive RSVPreF3-Mat or placebo between 24 weeks 0 days and 34 weeks 0 days of gestation. The primary outcomes were any or severe medically assessed RSV-associated lower respiratory tract disease in infants from birth to 6 months of age and safety in infants from birth to 12 months of age. After the observation of a higher risk of preterm birth in the vaccine group than in the placebo group, enrollment and vaccination were stopped early, and exploratory analyses of the safety signal of preterm birth were performed., Results: The analyses included 5328 pregnant women and 5233 infants; the target enrollment of approximately 10,000 pregnant women and their infants was not reached because enrollment was stopped early. A total of 3426 infants in the vaccine group and 1711 infants in the placebo group were followed from birth to 6 months of age; 16 and 24 infants, respectively, had any medically assessed RSV-associated lower respiratory tract disease (vaccine efficacy, 65.5%; 95% credible interval, 37.5 to 82.0), and 8 and 14, respectively, had severe medically assessed RSV-associated lower respiratory tract disease (vaccine efficacy, 69.0%; 95% credible interval, 33.0 to 87.6). Preterm birth occurred in 6.8% of the infants (237 of 3494) in the vaccine group and in 4.9% of those (86 of 1739) in the placebo group (relative risk, 1.37; 95% confidence interval [CI], 1.08 to 1.74; P = 0.01); neonatal death occurred in 0.4% (13 of 3494) and 0.2% (3 of 1739), respectively (relative risk, 2.16; 95% CI, 0.62 to 7.56; P = 0.23), an imbalance probably attributable to the greater percentage of preterm births in the vaccine group. No other safety signal was observed., Conclusions: The results of this trial, in which enrollment was stopped early because of safety concerns, suggest that the risks of any and severe medically assessed RSV-associated lower respiratory tract disease among infants were lower with the candidate maternal RSV vaccine than with placebo but that the risk of preterm birth was higher with the candidate vaccine. (Funded by GlaxoSmithKline Biologicals; ClinicalTrials.gov number, NCT04605159.)., (Copyright © 2024 Massachusetts Medical Society.)
- Published
- 2024
- Full Text
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5. Tailoring the hydrophobicity of graphene for its use as nanopores for DNA translocation.
- Author
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Schneider GF, Xu Q, Hage S, Luik S, Spoor JN, Malladi S, Zandbergen H, and Dekker C
- Subjects
- Bacteriophage M13 chemistry, Electric Conductivity, Hydrophobic and Hydrophilic Interactions, Nanopores ultrastructure, Porosity, Reproducibility of Results, Sensitivity and Specificity, Biosensing Techniques, DNA, Single-Stranded analysis, DNA, Viral analysis, Ethylene Glycols chemistry, Graphite chemistry, Pyrenes chemistry
- Abstract
Graphene nanopores are potential successors to biological and silicon-based nanopores. For sensing applications, it is however crucial to understand and block the strong nonspecific hydrophobic interactions between DNA and graphene. Here we demonstrate a novel scheme to prevent DNA-graphene interactions, based on a tailored self-assembled monolayer. For bare graphene, we encounter a paradox: whereas contaminated graphene nanopores facilitated DNA translocation well, clean crystalline graphene pores very quickly exhibit clogging of the pore. We attribute this to strong interactions between DNA nucleotides and graphene, yielding sticking and irreversible pore closure. We develop a general strategy to noncovalently tailor the hydrophobic surface of graphene by designing a dedicated self-assembled monolayer of pyrene ethylene glycol, which renders the surface hydrophilic. We demonstrate that this prevents DNA to adsorb on graphene and show that single-stranded DNA can now be detected in graphene nanopores with excellent nanopore durability and reproducibility.
- Published
- 2013
- Full Text
- View/download PDF
6. A direct ELISA assay for quantitative determination of the inhibitory potency of small molecules inhibitors for JNK3.
- Author
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Goettert M, Luik S, Graeser R, and Laufer SA
- Subjects
- Activating Transcription Factor 2 metabolism, Adenosine Triphosphate metabolism, Algorithms, Antibodies, Monoclonal, Antibodies, Phospho-Specific, Enzyme Inhibitors pharmacology, Hydrogen-Ion Concentration, Osmolar Concentration, Phosphorylation drug effects, Time Factors, Drug Discovery methods, Enzyme Inhibitors analysis, Enzyme Multiplied Immunoassay Technique, Mitogen-Activated Protein Kinase 10 antagonists & inhibitors
- Abstract
The c-jun N-terminal kinase 3 (JNK3) is a promising drug target for the treatment of neurological disorders. Here we report a direct ELISA including the optimization of a nonradioactive immunosorbent JNK3 activity assay to determine inhibitory potency of small-molecule inhibitors. Based on our previous JNK3 assay and our recently optimized p38α mitogen activated protein kinase (MAPK) protocol for monitoring the phosphorylation of activating-transcription factor 2 (ATF-2), we present a rapid and straightforward alternative to conventional radioactive and indirect ELISA kinase assays. To validate the assay with the optimized assay conditions we used reference compounds and achieved well comparable IC(50) results to published data. The use of a linked monoclonal antibody increased the specificity and the sensitivity of the assay, reducing the required antibody concentration by approximately 100-fold. The novel protocol is an accurate, easy-to-handle and robust screening assay for JNK3 and the assay performance was reduced from 7.5 to 3h., (Copyright © 2011 Elsevier B.V. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
7. One-pot synthesis of 4,6-diaryl-2-oxo(imino)-1,2-dihydropyridine-3-carbonitrile; a New Scaffold for p38alpha MAP kinase inhibition.
- Author
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Serry AM, Luik S, Laufer S, and Abadi AH
- Subjects
- Dihydropyridines chemistry, Molecular Structure, Nitriles chemistry, Small Molecule Libraries, Stereoisomerism, Structure-Activity Relationship, Combinatorial Chemistry Techniques, Dihydropyridines chemical synthesis, Dihydropyridines pharmacology, Nitriles chemical synthesis, Nitriles pharmacology, p38 Mitogen-Activated Protein Kinases antagonists & inhibitors
- Abstract
Two series of new compounds with the general formula 4,6-diaryl-2-oxo-1,2-dihydropyridine-3-carbonitriles and their isosteric 2-imino derivatives were synthesized by the multicomponent reaction of the appropriate acetophenone, aromatic aldehyde, ammonium acetate, and malononitrile or ethyl cyanoacetate. The products were obtained with excellent yields. The prepared compounds were evaluated for their in vitro ability to inhibit p38 alpha-MAP kinase. Several compounds showed p38 MAP kinase inhibitory properties with IC(50) as low as 0.07 microM. This is the first time to report compounds with such scaffold as p38 alpha-MAP kinase inhibitors. This asserts the potentiality of multicomponent reactions in drug discovery.
- Published
- 2010
- Full Text
- View/download PDF
8. Different methods for testing potential cyclooxygenase-1 and cyclooxygenase-2 inhibitors.
- Author
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Laufer S and Luik S
- Subjects
- Anti-Inflammatory Agents, Non-Steroidal pharmacology, Arachidonate 5-Lipoxygenase metabolism, Blood drug effects, Blood Platelets drug effects, Blood Platelets enzymology, Cyclooxygenase 1 metabolism, Cyclooxygenase 2 metabolism, Cyclooxygenase Inhibitors pharmacology, Dinoprostone blood, Dinoprostone metabolism, Drug Evaluation, Preclinical economics, Enzyme Assays economics, Enzyme-Linked Immunosorbent Assay methods, Granulocytes drug effects, Granulocytes enzymology, Humans, Leukotriene B4 metabolism, Lipopolysaccharides pharmacology, Anti-Inflammatory Agents, Non-Steroidal blood, Cyclooxygenase 1 blood, Cyclooxygenase 2 blood, Cyclooxygenase Inhibitors blood, Drug Evaluation, Preclinical methods, Enzyme Assays methods
- Abstract
The need for the development of selective agents, which only inhibit the mainly "harmful" cyclooxygenase-2 (COX-2) while leaving physiological COX-1 mostly unaffected, still remains, especially after the recent issues related to cardiovascular toxicity caused by some COX-2 selective agents. Thus there is still a demand for sensitive and rapid methods to assay for COX-2 selective agents. Among several in vitro testing systems the whole blood assay (WBA) is a well-known method to examine non-steroidal anti-inflammatory drugs (NSAIDs) in view of their potency to inhibit COX activity. This assay has some major advantages over enzyme-based or isolated cell assays. Emergence of artifacts due to cell separation steps is kept to a minimum and substances, even in disproportional high concentrations, can be examined outside the body in a physiological environment resembling most closely the in vivo conditions in living humans, i.e., 37 degrees C, homeostasis, presence of all blood compounds and cell-cell interactions remain intact. While COX-1 human whole blood assays are performed within less than 2 h, for established COX-2 assays one still has to allow for an overnight incubation step before gaining the desired plasma. The aim of the assay described in this chapter is to characterize an optimized human whole blood assay (hWBA). We present a simple, fast and reliable method to examine the capacity of NSAIDs at inhibiting COX-2 activity that can be applied for rapid and routine screening purposes.
- Published
- 2010
- Full Text
- View/download PDF
9. Participation of leukotriene C(4) in the regulation of suicidal erythrocyte death.
- Author
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Foller M, Mahmud H, Gu S, Wang K, Floride E, Kucherenko Y, Luik S, Laufer S, and Lang F
- Subjects
- Blotting, Western, Calcium metabolism, Caspase 3 metabolism, Caspase 8 metabolism, Cell Culture Techniques, Cell Death drug effects, Cell Size drug effects, Cells, Cultured, Erythrocyte Membrane drug effects, Erythrocyte Membrane metabolism, Erythrocytes metabolism, Glucose deficiency, Humans, Hydroxyurea analogs & derivatives, Hydroxyurea pharmacology, Leukotriene C4 antagonists & inhibitors, Leukotriene C4 pharmacology, Microscopy, Confocal, Phosphatidylserines pharmacology, Thiazoles pharmacology, Erythrocytes cytology, Erythrocytes drug effects, Leukotriene C4 physiology, Receptors, Leukotriene biosynthesis
- Abstract
Eryptosis, the suicidal death of erythrocytes, is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Eryptosis is triggered by increase in cytosolic Ca(2+) concentration upon energy depletion. The present study explored the involvement of leukotrienes. Western blotting was employed to detect the cysteinyl-leukotriene receptor cysLT1, competitive immune assay to determine leukotriene release from erythrocytes, Fluo3 fluorescence to estimate cytosolic Ca(2+) concentration, forward scatter to analyse cell volume and annexin V-binding to disclose phosphatidylserine exposure. As a result, erythrocytes expressed the leukotriene receptor CysLT1. Glucose depletion (24 hours) significantly increased the formation of the cysteinyl-leukotrienes C(4)/D(4)/E(4). Leukotriene C(4) (10 nM) increased Ca(2+) entry, decreased forward scatter, activated caspases 3 and 8, and stimulated annexin V-binding. Glucose depletion similarly increased annexin V-binding, an effect significantly blunted in the presence of the leukotriene receptor antagonist cinalukast (1 microM) or the 5-lipoxygenase inhibitor BW B70C (1 microM). In conclusion, upon energy depletion erythrocytes form leukotrienes, which in turn activate cation channels, leading to Ca(2+) entry, cell shrinkage and cell membrane scrambling. Cysteinyl-leukotrienes thus participate in the signaling of eryptosis during energy depletion.
- Published
- 2009
10. Novel lead structures for p38 MAP kinase via FieldScreen virtual screening.
- Author
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Cheeseright TJ, Holm M, Lehmann F, Luik S, Göttert M, Melville JL, and Laufer S
- Subjects
- Ligands, Models, Molecular, Molecular Conformation, Protein Kinase Inhibitors chemical synthesis, Protein Kinase Inhibitors chemistry, Protein Kinase Inhibitors metabolism, Structure-Activity Relationship, Thiadiazoles chemical synthesis, Thiadiazoles chemistry, Thiadiazoles metabolism, Thiadiazoles pharmacology, p38 Mitogen-Activated Protein Kinases chemistry, Drug Evaluation, Preclinical methods, Protein Kinase Inhibitors pharmacology, p38 Mitogen-Activated Protein Kinases antagonists & inhibitors
- Abstract
p38 MAP kinase has received considerable interest in the pharmaceutical industry and remains a valid and interesting target for the treatment of inflammation. To discover novel p38 inhibitors, we applied the ligand-based virtual screening technique, FieldScreen, to 1.2 million commercially available compounds. Fifty-eight diverse compounds were selected for biological analysis, using molecular field similarity to known inhibitors, while explicitly removing any structure that shared a scaffold with previously reported p38 inhibitors. Of these, 11 (19%) showed >or=20% inhibition of p38 at 10 microM. We chose to prepare analogues of two distinct chemical series resulting in a potential lead compound with pIC(50) of 6.4. Modeling of SAR using FieldAlign, a ligand alignment protocol, was used to rationalize the SAR of the series of thiadiazole based inhibitors.
- Published
- 2009
- Full Text
- View/download PDF
11. Biological studies on Brazilian plants used in wound healing.
- Author
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Schmidt C, Fronza M, Goettert M, Geller F, Luik S, Flores EM, Bittencourt CF, Zanetti GD, Heinzmann BM, Laufer S, and Merfort I
- Subjects
- Animals, Anti-Bacterial Agents pharmacology, Brazil, Caspase 3 metabolism, Cell Line, Cytotoxins pharmacology, Fibroblasts drug effects, Humans, Medicine, Traditional, Mice, Microbial Sensitivity Tests, NF-kappa B genetics, NF-kappa B metabolism, Pancreatic Elastase metabolism, Plant Extracts therapeutic use, Tumor Necrosis Factor-alpha metabolism, Wound Healing physiology, p38 Mitogen-Activated Protein Kinases metabolism, Magnoliopsida, Phytotherapy, Plant Extracts pharmacology, Plants, Medicinal, Wound Healing drug effects
- Abstract
Aim of the Study: n-Hexanic and ethanolic extracts from twelve plants (Brugmansia suaveolens Brecht. et Presl., Eupatorium laevigatum Lam., Galinsoga parviflora Cav., Iresine herbstii Hook., Kalanchöe tubiflora Hamet-Ahti, Petiveria alliacea L., Pluchea sagittalis (Lam.) Cabrera, Piper regnellii DC., Schinus molle L., Sedum dendroideum Moç et Sessé ex DC., Waltheria douradinha St. Hill., Xanthium cavanillesii Schouw.) used in traditional South Brazilian medicine as wound healing agents were investigated in various biological assays, targeting different aspects in this complex process., Materials and Methods: The extracts were investigated on NF-kappaB DNA binding, p38alpha MAPK, TNF-alpha release, direct elastase inhibition and its release as well as on caspase-3. Fibroblasts migration to and proliferation into the wounded monolayers were evaluated in the scratch assay, the agar diffusion test for antibacterial and the MTT assay for cytotoxic effects., Results: The hydrophilic extracts from Galinsoga parviflora, Petiveria alliacea, Schinus molle, Waltheria douradinha and Xanthium cavanillesii as well as the lipophilic extract of Waltheria douradinha turned out to be the most active ones., Conclusions: These results increase our knowledge on the wound healing effects of the investigated medicinal plants. Further studies are necessary to find out the effective secondary metabolites responsible for the observed effects.
- Published
- 2009
- Full Text
- View/download PDF
12. Development and optimization of a non-radioactive JNK3 assay.
- Author
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Peifer C, Luik S, Thuma S, Herweh Y, and Laufer S
- Subjects
- Adenosine Triphosphate, Drug Evaluation, Preclinical methods, Inhibitory Concentration 50, Reference Standards, Enzyme Inhibitors pharmacology, Immunosorbent Techniques, Mitogen-Activated Protein Kinase 10 antagonists & inhibitors
- Abstract
In light of emerging interest in the relevance of c-Jun NH2-terminal protein kinase 3 (JNK3) as a promising drug target, we describe here an advanced non-radioactive immunosorbent JNK3 activity assay that is applicable for routine screening of small molecule ATP-competitive enzyme inhibitors. We modified and established a JNK3/ATF-2 protocol based on our previously described p38 MAPK method [1] for a substrate-bound non-radioactive procedure that represents a convenient alternative to conventional radioactive protein kinase assays. The objective of the present study was to validate these conditions by using the reference compounds SP600125 and SB203580 to achieve comparable IC(50) results to published data. Furthermore, an IC(50) for staurosporine was determined. The protocol we describe here represents an accessible and robust screening assay for JNK3 inhibitors.
- Published
- 2006
- Full Text
- View/download PDF
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