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  1. Article ; Online: A novel assay based on pre-equilibrium titration curves for the determination of enzyme inhibitor binding kinetics.

    Noppen, Bernard / Vanbelle, Anouk / Stitt, Alan W / Vanhove, Marc

    European biophysics journal : EBJ

    2021  Volume 50, Issue 7, Page(s) 1037–1043

    Abstract: Selection of pharmacological agents based on potency measurements performed at equilibrium fail to incorporate the kinetic aspects of the drug-target interaction. Here we describe a method for screening or characterization of enzyme inhibitors that ... ...

    Abstract Selection of pharmacological agents based on potency measurements performed at equilibrium fail to incorporate the kinetic aspects of the drug-target interaction. Here we describe a method for screening or characterization of enzyme inhibitors that allows the concomitant determination of the equilibrium inhibition constant in unison with rates of complex formation and dissociation. The assay is distinct from conventional enzymatic assays and is based on the analysis of inhibition curves recorded prior to full equilibration of the system. The methodology is illustrated using bicyclic peptide inhibitors of the serine protease plasma kallikrein.
    MeSH term(s) Enzyme Inhibitors/pharmacology ; Kinetics ; Protein Binding ; Serine Endopeptidases
    Chemical Substances Enzyme Inhibitors ; Serine Endopeptidases (EC 3.4.21.-)
    Language English
    Publishing date 2021-06-22
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 283671-3
    ISSN 1432-1017 ; 0175-7571
    ISSN (online) 1432-1017
    ISSN 0175-7571
    DOI 10.1007/s00249-021-01554-0
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Systemic exposure following intravitreal administration of therapeutic agents: an integrated pharmacokinetic approach. 2. THR-687.

    Vanhove, Marc / Wagner, Jean-Marc / Noppen, Bernard / Jonckx, Bart / Vermassen, Elke / Stitt, Alan W

    Journal of pharmacokinetics and pharmacodynamics

    2021  Volume 48, Issue 6, Page(s) 837–849

    Abstract: Intravitreal (IVT) injection remains the preferred administration route of pharmacological agents intended for the treatment of back of the eye diseases such as diabetic macular edema (DME) and neovascular age-related macular degeneration (nvAMD). The ... ...

    Abstract Intravitreal (IVT) injection remains the preferred administration route of pharmacological agents intended for the treatment of back of the eye diseases such as diabetic macular edema (DME) and neovascular age-related macular degeneration (nvAMD). The procedure enables drugs to be delivered locally at high concentrations whilst limiting whole body exposure and associated risk of systemic adverse events. Nevertheless, intravitreally-delivered drugs do enter the general circulation and achieving an accurate understanding of systemic exposure is pivotal for the evaluation and development of drugs administered in the eye. We report here the full pharmacokinetic properties of THR-687, a pan RGD integrin antagonist currently in clinical development for the treatment of DME, in both rabbit and minipig. Pharmacokinetic characterization included description of vitreal elimination, of systemic pharmacokinetics, and of systemic exposure following IVT administration. For the latter, we present a novel pharmacokinetic model that assumes clear partition between the vitreous humor compartment itself where the drug is administered and the central systemic compartment. We also propose an analytical solution to the system of differential equations that represent the pharmacokinetic model, thereby allowing data analysis with standard nonlinear regression analysis. The model accurately describes circulating levels of THR-687 following IVT administration in relevant animal models, and we suggest that this approach is relevant to a range of drugs and analysis of subsequent systemic exposure.
    MeSH term(s) Animals ; Diabetic Retinopathy/drug therapy ; Intravitreal Injections ; Macular Edema/drug therapy ; Rabbits ; Swine ; Swine, Miniature ; Vitreous Body
    Language English
    Publishing date 2021-07-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2041601-5
    ISSN 1573-8744 ; 1567-567X
    ISSN (online) 1573-8744
    ISSN 1567-567X
    DOI 10.1007/s10928-021-09774-9
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Systemic exposure following intravitreal administration of therapeutic agents: an integrated pharmacokinetic approach. 1. THR-149.

    Vanhove, Marc / Noppen, Bernard / Wagner, Jean-Marc / Van Bergen, Tine / Barbeaux, Philippe / Stitt, Alan W

    Journal of pharmacokinetics and pharmacodynamics

    2021  Volume 48, Issue 6, Page(s) 825–836

    Abstract: Intravitreal (IVT) injection of pharmacological agents is an established and widely used procedure for the treatment of many posterior segment of the eye diseases. IVT injections permit drugs to reach high concentrations in the retina whilst limiting ... ...

    Abstract Intravitreal (IVT) injection of pharmacological agents is an established and widely used procedure for the treatment of many posterior segment of the eye diseases. IVT injections permit drugs to reach high concentrations in the retina whilst limiting systemic exposure. Beyond the risk of secondary complications such as intraocular infection, the potential of systemic adverse events cannot be neglected. Therefore, a detailed understanding of the rules governing systemic exposure following IVT drug administration remains a prerequisite for the evaluation and development of new pharmacological agents intended for eye delivery. We present here a novel mathematical model to describe and predict circulating drug levels following IVT in the rabbit eye, a species which is widely used for drug delivery, pharmacokinetic, and pharmacodynamic studies. The mathematical expression was derived from a pharmacokinetic model that assumes the existence of a compartment between the vitreous humor compartment itself and the systemic compartment. We show that the model accurately describes circulating levels of THR-149, a plasma kallikrein inhibitor in development for the treatment of diabetic macular edema. We hypothesize that the model based on the rabbit eye has broader relevance to the human eye and can be used to analyze systemic exposure of a variety of drugs delivered in the eye.
    MeSH term(s) Animals ; Diabetic Retinopathy/drug therapy ; Macular Edema/drug therapy ; Macular Edema/metabolism ; Pharmaceutical Preparations/metabolism ; Rabbits ; Retina/metabolism ; Vitreous Body/metabolism
    Chemical Substances Pharmaceutical Preparations
    Language English
    Publishing date 2021-07-23
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2041601-5
    ISSN 1573-8744 ; 1567-567X
    ISSN (online) 1573-8744
    ISSN 1567-567X
    DOI 10.1007/s10928-021-09773-w
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Intravitreally Injected Fluid Dispersion: Importance of Injection Technique.

    Willekens, Koen / Reyns, Geert / Diricx, Marjan / Vanhove, Marc / Noppen, Bernard / Coudyzer, Walter / Ni, Yicheng / Feyen, Jean H M / Stalmans, Peter

    Investigative ophthalmology & visual science

    2017  Volume 58, Issue 3, Page(s) 1434–1441

    Abstract: Purpose: The purpose of this study was to evaluate the dispersion of intravitreally injected solutions and investigate the influence of varying injection techniques.: Methods: This was a prospective study using enucleated porcine eyes and ultra-high- ... ...

    Abstract Purpose: The purpose of this study was to evaluate the dispersion of intravitreally injected solutions and investigate the influence of varying injection techniques.
    Methods: This was a prospective study using enucleated porcine eyes and ultra-high-resolution computed tomography (UHRCT) scanning to visualize iomeprol intravitreal dispersion. Sixty eyes were divided over 12 different groups according to the injection procedure: fast (2 seconds) or slow (10 seconds) injection speed and needle tip location (6- and 12-mm needle shaft insertion or premacular tip placement verified by indirect ophthalmoscopy). For each of these combinations, eyes were either injected with the combination of V20I (which is an analogue of ocriplasmin) and iomeprol or iomeprol alone. Distance to the macula and volume measurements were performed at 1, 2, 3, and 5 hours after injection.
    Results: The measured contrast bolus volume increases slowly over time to an average of 0.70 (P = 0.03), 1.04 (P = 0.006), and 0.79 (P = 0.0001) cm3 5 hours after the injection for the 6-mm needle shaft insertion, 12-mm needle shaft insertion, and premacular needle tip placement, respectively. The distance to the macular marker was significantly lower for premacular needle tip placement injections compared with 6- and 12-mm needle shaft insertion depths.
    Conclusions: Ultra-high-resolution computed tomography with three-dimensional reconstruction offers the possibility to study the dispersion of intravitreally injected solutions in a noninvasive manner. Intravitreal premacular solution delivery is possible with an indirect ophthalmoscope-guided injection technique and significantly reduces the time to reach the posterior pole in respect to 6- and 12-mm needle insertion depths. The speed of injection does not influence dispersion significantly.
    MeSH term(s) Animals ; Contrast Media/administration & dosage ; Drug Combinations ; Electroretinography ; Equipment Design ; Fibrinolysin/administration & dosage ; Fibrinolysin/pharmacokinetics ; Follow-Up Studies ; Imaging, Three-Dimensional ; Intravitreal Injections/instrumentation ; Iopamidol/administration & dosage ; Iopamidol/analogs & derivatives ; Iopamidol/pharmacokinetics ; Models, Animal ; Ophthalmoscopy ; Peptide Fragments/administration & dosage ; Peptide Fragments/pharmacokinetics ; Pilot Projects ; Prospective Studies ; Swine ; Tomography, X-Ray Computed ; Vitreous Body/diagnostic imaging ; Vitreous Body/metabolism
    Chemical Substances Contrast Media ; Drug Combinations ; Peptide Fragments ; iomeprol (17E17JBP8L) ; microplasmin (7V6HE3DM5A) ; Fibrinolysin (EC 3.4.21.7) ; Iopamidol (JR13W81H44)
    Language English
    Publishing date 2017-03-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 391794-0
    ISSN 1552-5783 ; 0146-0404
    ISSN (online) 1552-5783
    ISSN 0146-0404
    DOI 10.1167/iovs.16-20543
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Dysregulation of the kallikrein-kinin system in bronchoalveolar lavage fluid of patients with severe COVID-19.

    Martens, Caroline P / Van Mol, Pierre / Wauters, Joost / Wauters, Els / Gangnus, Tanja / Noppen, Bernard / Callewaert, Hanne / Feyen, Jean H M / Liesenborghs, Laurens / Heylen, Elisabeth / Jansen, Sander / Pereira, Leydi Carolina Velásquez / Kraisin, Sirima / Guler, Ipek / Engelen, Matthias M / Ockerman, Anna / Van Herck, Anke / Vos, Robin / Vandenbriele, Christophe /
    Meersseman, Philippe / Hermans, Greet / Wilmer, Alexander / Martinod, Kimberly / Burckhardt, Bjoern B / Vanhove, Marc / Jacquemin, Marc / Verhamme, Peter / Neyts, Johan / Vanassche, Thomas

    EBioMedicine

    2022  Volume 83, Page(s) 104195

    Abstract: Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to the angiotensin-converting enzyme 2 (ACE2) receptor, a critical component of the kallikrein-kinin system. Its dysregulation may lead to increased vascular permeability and ...

    Abstract Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to the angiotensin-converting enzyme 2 (ACE2) receptor, a critical component of the kallikrein-kinin system. Its dysregulation may lead to increased vascular permeability and release of inflammatory chemokines. Interactions between the kallikrein-kinin and the coagulation system might further contribute to thromboembolic complications in COVID-19.
    Methods: In this observational study, we measured plasma and tissue kallikrein hydrolytic activity, levels of kinin peptides, and myeloperoxidase (MPO)-DNA complexes as a biomarker for neutrophil extracellular traps (NETs), in bronchoalveolar lavage (BAL) fluid from patients with and without COVID-19.
    Findings: In BAL fluid from patients with severe COVID-19 (n = 21, of which 19 were mechanically ventilated), we observed higher tissue kallikrein activity (18·2 pM [1·2-1535·0], median [range], n = 9 vs 3·8 [0·0-22·0], n = 11; p = 0·030), higher levels of the kinin peptide bradykinin-(1-5) (89·6 [0·0-2425·0], n = 21 vs 0·0 [0·0-374·0], n = 19, p = 0·001), and higher levels of MPO-DNA complexes (699·0 ng/mL [66·0-142621·0], n = 21 vs 70·5 [9·9-960·0], n = 19, p < 0·001) compared to patients without COVID-19.
    Interpretation: Our observations support the hypothesis that dysregulation of the kallikrein-kinin system might occur in mechanically ventilated patients with severe pulmonary disease, which might help to explain the clinical presentation of patients with severe COVID-19 developing pulmonary oedema and thromboembolic complications. Therefore, targeting the kallikrein-kinin system should be further explored as a potential treatment option for patients with severe COVID-19.
    Funding: Research Foundation-Flanders (G0G4720N, 1843418N), KU Leuven COVID research fund.
    MeSH term(s) Angiotensin-Converting Enzyme 2 ; Bradykinin ; Bronchoalveolar Lavage Fluid ; COVID-19 ; Humans ; Kallikrein-Kinin System ; Kallikreins/metabolism ; Peroxidase/metabolism ; SARS-CoV-2 ; Tissue Kallikreins/metabolism
    Chemical Substances Peroxidase (EC 1.11.1.7) ; Angiotensin-Converting Enzyme 2 (EC 3.4.17.23) ; Kallikreins (EC 3.4.21.-) ; Tissue Kallikreins (EC 3.4.21.35) ; Bradykinin (S8TIM42R2W)
    Language English
    Publishing date 2022-08-05
    Publishing country Netherlands
    Document type Journal Article ; Observational Study
    ZDB-ID 2851331-9
    ISSN 2352-3964
    ISSN (online) 2352-3964
    DOI 10.1016/j.ebiom.2022.104195
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  6. Article ; Online: Mechanism of inactivation of ocriplasmin in porcine vitreous.

    Aerts, Frans / Noppen, Bernard / Fonteyn, Laetitia / Derua, Rita / Waelkens, Etienne / de Smet, Marc D / Vanhove, Marc

    Biophysical chemistry

    2012  Volume 165-166, Page(s) 30–38

    Abstract: Ocriplasmin, a 249-amino acid recombinant C-terminal fragment of human plasmin, has the potential to degrade, within the eye, the protein scaffold that links the vitreous to the retina. This may be beneficial to the treatment of a number of important ... ...

    Abstract Ocriplasmin, a 249-amino acid recombinant C-terminal fragment of human plasmin, has the potential to degrade, within the eye, the protein scaffold that links the vitreous to the retina. This may be beneficial to the treatment of a number of important ophthalmic indications, such as symptomatic vitreomacular adhesion. We demonstrate here that ocriplasmin used at therapeutically-relevant concentrations is inactivated in porcine vitreous through autolytic degradation. Autolytic cleavage occurs at a limited number of sites, primarily K156-E157, K166-V167 and R177-V178, which, as predicted, contain a positively-charged arginine or lysine residue at the P1 position. Our data also suggest that autolytic degradation requires at least local or partial unfolding of the protein.
    MeSH term(s) Amino Acid Sequence ; Animals ; Buffers ; Disulfides/chemistry ; Fibrinolysin/chemistry ; Fibrinolysin/metabolism ; Hydrogen-Ion Concentration ; Kinetics ; Molecular Sequence Data ; Peptide Fragments/chemistry ; Peptide Fragments/metabolism ; Protein Stability ; Protein Unfolding ; Proteolysis ; Swine ; Vitreous Body/metabolism
    Chemical Substances Buffers ; Disulfides ; Peptide Fragments ; microplasmin (7V6HE3DM5A) ; Fibrinolysin (EC 3.4.21.7)
    Language English
    Publishing date 2012-05
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 185052-0
    ISSN 1873-4200 ; 0301-4622
    ISSN (online) 1873-4200
    ISSN 0301-4622
    DOI 10.1016/j.bpc.2012.03.002
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Characterization of a stabilized form of microplasmin for the induction of posterior vitreous detachment.

    Gad Elkareem, Ashraf M / Willekens, Ben / Vanhove, Marc / Noppen, Bernard / Stassen, Jean Marie / de Smet, Marc D

    Current eye research

    2010  Volume 35, Issue 10, Page(s) 909–915

    Abstract: Purpose: To investigate the stability and safety of a diluted acidified form of microplasmin and its ability to induce a posterior vitreous detachment (PVD) following intravitreal injection in post-mortem porcine eyes.: Methods: Microplasmin diluted ... ...

    Abstract Purpose: To investigate the stability and safety of a diluted acidified form of microplasmin and its ability to induce a posterior vitreous detachment (PVD) following intravitreal injection in post-mortem porcine eyes.
    Methods: Microplasmin diluted in normal saline (NS) and balanced salt solution (BSS+) was assayed for residual activity by hydrolysis of the chromogenic substrate Glu-Phe-Lys-pNA. Residual activity on vitreous was determined by injecting aliquots of microplasmin reconstituted in balanced salt solution (BSS+) or normal saline (NS) kept at room temperature (RT) for up to 1 hr, then injected in aliquots of porcine vitreous and incubated for 2 hr at 37°C. The breakdown products were submitted to SDS Page electrophoresis and compared to determine the level of enzymatic activity. Pig eyes were incubated with graded concentrations of microplasmin 0.625, 1.25, or 2.50 mg/mL reconstituted in BBS+ or NS. Morphologic alterations and the ability to induce a PVD was assessed by light and electron microscopy.
    Results: Microplasmin's enzymatic activity in an in vitro assay in BSS+ was 70% of its baseline value after 30 min, and about 50% after 60 min at RT. The corresponding effect on degradation of vitreous gel was 60 and 40% baseline at 30 and 60 min. There was no loss of activity in the microplasmin diluted in normal saline over this time period. Dilution of acidified microplasmin in normal saline did not lead to structural changes within the retina. A dose dependent PVD was observed in eyes treated with microplasmin diluted in NS.
    Conclusions: Acidified (stabilized) microplasmin has the same intraocular activity profile as microplasmin at a neutral pH. Better retention of activity at room temperature makes it a better candidate for use in clinical practice.
    MeSH term(s) Acids ; Animals ; Dose-Response Relationship, Drug ; Drug Administration Schedule ; Electrophoresis, Polyacrylamide Gel ; Fibrinolysin/administration & dosage ; Fibrinolysin/chemistry ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Injections, Intraocular ; Microscopy, Electron ; Osmolar Concentration ; Peptide Fragments/administration & dosage ; Peptide Fragments/chemistry ; Sodium Chloride ; Solutions ; Swine ; Temperature ; Time Factors ; Vitreous Body/drug effects ; Vitreous Body/pathology ; Vitreous Detachment/chemically induced ; Vitreous Detachment/pathology
    Chemical Substances Acids ; Peptide Fragments ; Solutions ; Sodium Chloride (451W47IQ8X) ; microplasmin (7V6HE3DM5A) ; Fibrinolysin (EC 3.4.21.7)
    Language English
    Publishing date 2010-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 82079-9
    ISSN 1460-2202 ; 0271-3683
    ISSN (online) 1460-2202
    ISSN 0271-3683
    DOI 10.3109/02713683.2010.494819
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Inhibition of human immunodeficiency virus type 1 transcription by N-aminoimidazole derivatives.

    Stevens, Miguel / Balzarini, Jan / Lagoja, Irene M / Noppen, Bernard / François, Katrien / Van Aerschot, Arthur / Herdewijn, Piet / De Clercq, Erik / Pannecouque, Christophe

    Virology

    2007  Volume 365, Issue 1, Page(s) 220–237

    Abstract: This study describes the mechanism of antiviral action of the N-aminoimidazole derivatives which exclusively inhibit retroviruses such as HIV-1, HIV-2, SIV and MSV. These antiretroviral compounds, with lead prototype NR-818, were found to inhibit HIV-1 ... ...

    Abstract This study describes the mechanism of antiviral action of the N-aminoimidazole derivatives which exclusively inhibit retroviruses such as HIV-1, HIV-2, SIV and MSV. These antiretroviral compounds, with lead prototype NR-818, were found to inhibit HIV-1 replication at the transcriptional level. Analysis of each individual step of viral transcription, including transcriptional activation mediated by NF-kappaB, the chromatin remodeling process at the viral promoter and viral mRNA transcription mediated by RNAPII, showed that NR-818 was able to prolong the binding of NF-kappaB to its consensus sequence. The compound also increased the acetylation of histones H3 and H4 within the nucleosome nuc-1 at the transcription initiation site and inhibited the recruitment of viral Tat and the phosphorylation of the RNA polymerase II C-terminal domain (RNAPII CTD) at the viral promoter upon stimulation of latently HIV-1-infected cell lines. As a result, viral mRNA expression and subsequent viral p24 production in stimulated latently HIV-1-infected cell lines was suppressed by NR-818. These data suggest that the N-aminoimidazole derivatives effectively inhibit the reactivation of HIV-1 and may contribute to the control of the latent HIV-1 reservoir.
    MeSH term(s) Cell Line ; Enzyme Inhibitors/pharmacology ; Gene Products, tat/metabolism ; HIV-1/drug effects ; HIV-1/genetics ; HIV-1/metabolism ; Humans ; Imidazoles/chemistry ; Imidazoles/pharmacology ; Promoter Regions, Genetic ; Transcription, Genetic/drug effects ; Transcriptional Activation ; Virus Latency ; tat Gene Products, Human Immunodeficiency Virus
    Chemical Substances Enzyme Inhibitors ; Gene Products, tat ; Imidazoles ; tat Gene Products, Human Immunodeficiency Virus
    Language English
    Publishing date 2007-08-15
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 200425-2
    ISSN 1096-0341 ; 0042-6822
    ISSN (online) 1096-0341
    ISSN 0042-6822
    DOI 10.1016/j.virol.2007.03.036
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