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1.
Lung Cancer ; 184: 107356, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37660479

RESUMO

OBJECTIVES: CEACAM5 is a cell-surface glycoprotein expressed on epithelial cells of some solid tumors. Tusamitamab ravtansine (SAR408701), a humanized antibody-drug conjugate targeting CEACAM5, is in clinical development for nonsquamous non-small cell lung cancer (NSQ-NSCLC) with CEACAM5 high expression (HE), defined as membranous CEACAM5 immunohistochemistry staining at ≥ 2+ intensity in ≥ 50% of tumor cells. MATERIALS AND METHODS: We investigated correlations between CEACAM5 expression by immunohistochemistry, CEACAM5 protein expression by ELISA, and CEACAM5 RNA expression by RNA-seq in NSQ-NSCLC patient-derived xenograft (PDX) models, and tumor responses to tusamitamab ravtansine in these models. We assessed prevalence of CEACAM5 HE, clinicopathologic characteristics and molecular markers in patients with NSQ-NSCLC in clinical cohorts. RESULTS: In a lung PDX set of 10 NSQ-NSCLC specimens, correlations between CEACAM5 by IHC, ELISA and RNA-seq ranged from 0.72 to 0.88. In a larger lung PDX set, higher H-scores were present in NSQ- (n = 93) vs SQ-NSCLC (n = 128) models, and in 12 of these NSQ-NSCLC models, more tumor responses to tusamitamab ravtansine occurred in CEACAM5 HE (5/8; 62.5%) versus moderate or negative expression (1/4; 25%), including 3 with KRAS mutations among the 6 responders. In clinical NSQ-NSCLC samples, CEACAM5 HE prevalence was (52/214; 24.3%) in primary tumors and (6/17; 35.3%) in metastases. In NSQ-NSCLC primary tumors, CEACAM5 HE prevalence was significantly higher in KRAS-altered versus wild-type (35.0% vs 19.5%; P = 0.028) and in programmed cell death ligand 1 (PD-L1) negative (tumor cells 0%)/low (1-49%) versus high (≥50%) (33.3%, 26.1%, 5.0%; P = 0.031), but not significantly different in EGFR-mutated versus wild-type (20.0% vs 25.7%, P = 0.626). CONCLUSIONS: In NSQ-NSCLC tumors, CEACAM5 HE prevalence was 24.3% overall and was higher with KRAS altered and with PD-L1 negative/low tumors but similar regardless of EGFR mutation status. These findings support targeting CEACAM5 and the clinical development of tusamitamab ravtansine for patients with NSQ-NSCLC with CEACAM5 HE.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Animais , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Antígeno B7-H1 , Antígeno Carcinoembrionário/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Modelos Animais de Doenças , Receptores ErbB
2.
BMC Cancer ; 22(1): 639, 2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35689194

RESUMO

Malignant pleural mesothelioma, a tumor arising from the membrane covering the lungs and the inner side of the ribs, is a cancer in which genetic alterations of genes encoding proteins that act on or are part of the Hippo-YAP1 signaling pathway are frequent. Dysfunctional Hippo signaling may result in aberrant activation of the transcriptional coactivator protein YAP1, which binds to and activates transcription factors of the TEAD family. Recent studies have associated elevated YAP1 protein activity with a poor prognosis of malignant mesothelioma and its resistance to current therapies, but its role in tumor maintenance is unclear. In this study, we investigate the dependence of malignant mesothelioma on YAP1 signaling to maintain fully established tumors in vivo. We show that downregulation of YAP1 in a dysfunctional Hippo genetic background results in the inhibition of YAP1/TEAD-dependent gene expression, the induction of apoptosis, and the inhibition of tumor cell growth in vitro. The conditional downregulation of YAP1 in established tumor xenografts leads to the inhibition of YAP1-dependent gene transcription and eventually tumor regression. This effect is only seen in the YAP1-activated MSTO-211H mesothelioma xenograft model, but not in the Hippo-independent HCT116 colon cancer xenograft model. Our data demonstrate that, in the context of a Hippo pathway mutated background, YAP1 activity alone is enough to maintain the growth of established tumors in vivo, thus validating the concept of inhibiting the activated YAP1-TEAD complex for the treatment of malignant pleural mesothelioma patients.


Assuntos
Mesotelioma Maligno , Mesotelioma , Linhagem Celular Tumoral , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Humanos , Mesotelioma/patologia , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Proteínas de Sinalização YAP
4.
Clin Cancer Res ; 26(24): 6589-6599, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33046521

RESUMO

PURPOSE: Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) is a glycoprotein that has limited expression in normal adult tissues, but is overexpressed in carcinomas of the gastrointestinal tract, the genitourinary and respiratory systems, and breast cancer. As such, CEACAM5 is an attractive target for antibody-based therapies designed to selectively deliver cytotoxic drugs to certain epithelial tumors. Here, we describe preclinical data for a novel antibody-drug conjugate (ADC), SAR408701, which consists of an anti-CEACAM5 antibody (SAR408377) coupled to a maytansinoid agent DM4 via a cleavable linker. EXPERIMENTAL DESIGN: The specificity and binding affinity of SAR408701 to human and cynomolgus monkey CEACAM5 were tested in vitro. The cytotoxic activity of SAR408701 was assessed in CEACAM5-expressing tumor cell lines and using patient-derived xenograft mouse models of CEACAM5-positive tumors. Pharmacokinetic-pharmacodynamic and pharmacokinetic-efficacy relationships were established. SAR408701 toxicity was evaluated in cynomolgus monkey. RESULTS: SAR408701 bound selectively to human and cynomolgus monkey CEACAM5 with similar apparent Kd values (0.017 nmol/L and 0.024 nmol/L, respectively). Both in vitro and in vivo evaluations showed that SAR408701 has cytotoxic activity, leading to in vivo efficacy in single and repeated dosing. Single doses of SAR408701 induced significant increases in the tumor expression of phosphorylated histone H3, confirming the tubulin-targeting mechanism of action. The overall toxicity profile of SAR408701 in cynomolgus monkey was similar to that observed after intravenous administration of DM4 alone. CONCLUSIONS: On the basis of these preclinical data, the ADC SAR408701 is a promising candidate for development as a potential treatment for patients with CEACAM5-positive tumors.


Assuntos
Anticorpos Monoclonais/química , Anticorpos/farmacologia , Antineoplásicos/farmacologia , Imunoconjugados/farmacologia , Maitansina/química , Neoplasias Epiteliais e Glandulares/tratamento farmacológico , Animais , Anticorpos/química , Anticorpos/uso terapêutico , Anticorpos Monoclonais/imunologia , Antineoplásicos/química , Apoptose , Antígeno Carcinoembrionário/imunologia , Proliferação de Células , Feminino , Proteínas Ligadas por GPI/antagonistas & inibidores , Proteínas Ligadas por GPI/imunologia , Humanos , Macaca fascicularis , Camundongos , Camundongos SCID , Neoplasias Epiteliais e Glandulares/imunologia , Neoplasias Epiteliais e Glandulares/patologia , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
5.
Philos Trans A Math Phys Eng Sci ; 378(2175): 20190398, 2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32564725

RESUMO

The fragmentation of small, brittle, flexible, inextensible fibres is investigated in a fully developed, homogeneous, isotropic turbulent flow. Such small fibres spend most of their time fully stretched and their dynamics follows that of stiff rods. They can then break through tensile failure, i.e. when the tension is higher than a given threshold. Fibres bend when experiencing a strong compression. During these rare and intermittent buckling events, they can break under flexural failure, i.e. when the curvature exceeds a threshold. Fine-scale massive simulations of both the fluid flow and the fibre dynamics are performed to provide statistics on these two fragmentation processes. This gives ingredients for the development of accurate macroscopic models, namely the fragmentation rate and daughter-size distributions, which can be used to predict the time evolution of the fibre size distribution. Evidence is provided for the generic nature of turbulent fragmentation and of the resulting population dynamics. It is indeed shown that the statistics of break-up is fully determined by the probability distribution of Lagrangian fluid velocity gradients. This approach singles out that the only relevant dimensionless parameter is a local flexibility which balances flow stretching to the fibre elastic forces. This article is part of the theme issue 'Fluid dynamics, soft matter and complex systems: recent results and new methods'.

6.
Antiviral Res ; 159: 84-94, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30268914

RESUMO

Human cytomegalovirus (HCMV) is a major human pathogen with seropositivity rates in the adult population ranging between 40% and 95%. HCMV infection is associated with severe pathology, such as life-threatening courses of infection in immunocompromised individuals and neonates. Current standard therapy with valganciclovir has the disadvantage of adverse side effects and viral drug resistance. A novel anti-HCMV drug, letermovir, has been approved recently, so that improved therapy options are available. Nevertheless, even more so far unexploited classes of compounds and molecular modes of action will be required for a next generation of antiherpesviral treatment strategies. In this study, we focused on the analysis of the antiviral potency of a novel class of compounds, i.e. pyrrolopyridine analogs, and identified both hit compounds and their target protein candidates. In essence, we provide novel evidence as follows: (i) screening hit SC88941 is highly active in inhibiting HCMV replication in primary human fibroblasts with an EC50 value of 0.20 ±â€¯0.01 µM in the absence of cytotoxicity, (ii) inhibition occurs at the early-late stage of viral protein production and shows reinforcing effects upon LMV cotreatment, (iii) among the viruses analyzed, antiviral activity was most pronounced against ß-herpesviruses (HCMV, HHV-6A) and intermediate against adenovirus (HAdV-2), (iv) induction of SC88941 resistance was not detectable, thus differed from the induction of ganciclovir resistance, (v) a linker-coupled model compound was used for mass spectrometry-based target identification, thus yielding several drug-binding target proteins and (vi) a first confocal imaging approach used for addressing intracellular effects of SC88941 indicated qualitative and quantitative alteration of viral protein expression and localization. Thus, our findings suggest a multifaceted pattern of compound-target binding in connection with an unusual mode of action, opening up further opportunities of antiviral drug development.


Assuntos
Antivirais/farmacologia , Citomegalovirus/efeitos dos fármacos , Pirimidinas/farmacologia , Pirróis/farmacologia , Proteínas Virais/metabolismo , Adenoviridae/efeitos dos fármacos , Antivirais/síntese química , Descoberta de Drogas , Farmacorresistência Viral , Fibroblastos/virologia , Herpesviridae/efeitos dos fármacos , Humanos , Espectrometria de Massas , Orthomyxoviridae/efeitos dos fármacos , Pirimidinas/síntese química , Pirróis/síntese química , Replicação Viral/efeitos dos fármacos
7.
Phys Rev Lett ; 121(15): 154501, 2018 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-30362808

RESUMO

Small flexible fibers in a turbulent flow are found to be as straight as stiff rods most of the time. This is due to the cooperative action of flexural rigidity and fluid stretching. However, fibers might bend and buckle when they tumble and experience a strong enough local compression. Such events are similar to an activation process, where the role of temperature is played by the inverse of Young's modulus. Numerical simulations show that buckling occurs very intermittently in time. This results from unexpected long-range Lagrangian correlations of the turbulent shear.

8.
Phys Rev E ; 98(2-1): 023107, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30253530

RESUMO

This paper investigates the effect of inertia on the dynamics of elongated chains to go beyond the overdamped case that is often used to study such systems. For that purpose, numerical simulations are performed considering the motion of freely jointed bead-rod chains in an extensional flow in the presence of thermal noise. The coil-stretch transition and the tumbling instability are characterized as a function of three parameters: the Péclet number, the Stokes number, and the chain length. Numerical results show that the coil-stretch transition remains when inertia is present and that it depends nonlinearly on the Stokes and Péclet numbers. Theoretical and numerical analyses also highlight the role of intermediate stable configurations in the dynamics of elongated chains: chains can indeed remain trapped for a certain time in these configurations, especially while undergoing a tumbling event.

9.
Antiviral Res ; 143: 113-121, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28400201

RESUMO

Infection with human cytomegalovirus (HCMV) is a serious medical problem, particularly in immunocompromised individuals and neonates. The success of (val)ganciclovir therapy is hampered by low drug compatibility and induction of viral resistance. A novel strategy of antiviral treatment is based on the exploitation of cell-directed signaling, e. g. pathways with a known relevance for carcinogenesis and tumor drug development. Here we describe a principle for putative antiviral drugs based on targeting dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs). DYRKs constitute an evolutionarily conserved family of protein kinases with key roles in the control of cell proliferation and differentiation. Members of the DYRK family are capable of phosphorylating a number of substrate proteins, including regulators of the cell cycle, e.g. DYRK1B can induce cell cycle arrest, a critical step for the regulation of HCMV replication. Here we provide first evidence for a critical role of DYRKs during viral replication and the high antiviral potential of DYRK inhibitors (SC84227, SC97202 and SC97208, Harmine and AZ-191). Using established replication assays for laboratory and clinically relevant strains of HCMV, concentration-dependent profiles of inhibition were obtained. Mean inhibitory concentrations (EC50) of 0.98 ± 0.08 µM/SC84227, 0.60 ± 0.02 µM/SC97202, 6.26 ± 1.64 µM/SC97208, 0.71 ± 0.019 µM/Harmine and 0.63 ± 0.23 µM/AZ-191 were determined with HCMV strain AD169-GFP for the infection of primary human fibroblasts. A first analysis of the mode of antiviral action suggested a block of viral replication at the early-late stage of HCMV gene expression. Moreover, rhesus macaque cytomegalovirus (RhCMV), varicella-zoster virus (VZV) and herpes simplex virus (HSV-1) showed a similarly high sensitivity to these compounds. Thus, we conclude that DYRK signaling represents a promising target pathway for the development of novel anti-herpesviral strategies.


Assuntos
Antivirais/antagonistas & inibidores , Herpesviridae/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/efeitos dos fármacos , Proteínas Tirosina Quinases/efeitos dos fármacos , Animais , Ciclo Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Citomegalovirus/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Descoberta de Drogas , Fibroblastos/virologia , Ganciclovir/antagonistas & inibidores , Técnicas de Silenciamento de Genes , Harmina/antagonistas & inibidores , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 3/efeitos dos fármacos , Humanos , Macaca mulatta/virologia , Testes de Sensibilidade Microbiana , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Sensibilidade e Especificidade , Transdução de Sinais/efeitos dos fármacos , Células Vero , Replicação Viral/efeitos dos fármacos , Quinases Dyrk
10.
Cell ; 165(2): 317-30, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-27058664

RESUMO

BRAF(V600E) mutant colon cancers (CCs) have a characteristic gene expression signature that is also found in some tumors lacking this mutation. Collectively, they are referred to as "BRAF-like" tumors and represent some 20% of CCs. We used a shRNA-based genetic screen focused on genes upregulated in BRAF(V600E) CCs to identify vulnerabilities of this tumor subtype that might be exploited therapeutically. Here, we identify RANBP2 (also known as NUP358) as essential for survival of BRAF-like, but not for non-BRAF-like, CC cells. Suppression of RANBP2 results in mitotic defects only in BRAF-like CC cells, leading to cell death. Mechanistically, RANBP2 silencing reduces microtubule outgrowth from the kinetochores, thereby inducing spindle perturbations, providing an explanation for the observed mitotic defects. We find that BRAF-like CCs display far greater sensitivity to the microtubule poison vinorelbine both in vitro and in vivo, suggesting that vinorelbine is a potential tailored treatment for BRAF-like CCs.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Vimblastina/análogos & derivados , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Células Cultivadas , Neoplasias do Colo/classificação , Neoplasias do Colo/tratamento farmacológico , Xenoenxertos , Humanos , Camundongos , Camundongos Nus , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Chaperonas Moleculares/genética , Transplante de Neoplasias , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Proteínas Proto-Oncogênicas B-raf/genética , Vimblastina/administração & dosagem , Vimblastina/farmacologia , Vinorelbina
11.
Mol Cancer Ther ; 13(6): 1636-44, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24688047

RESUMO

The recombinant fusion protein aflibercept (ziv-aflibercept in the United States) binds VEGF-A, VEGF-B, and placental growth factor (PlGF). The monoclonal antibody bevacizumab binds VEGF-A. Recent studies hypothesized that dual targeting of VEGF/PlGF is more beneficial than targeting either ligand. We compared activity of aflibercept versus bevacizumab in 48 patient-derived xenograft (PDX) colorectal cancer models. Nude mice engrafted subcutaneously with PDX colorectal cancer tumors received biweekly aflibercept, bevacizumab, or vehicle injections. Differential activity between aflibercept and bevacizumab, determined by mouse (m), human (h), VEGF-A, and PlGF levels in untreated tumors, was measured. Aflibercept induced complete tumor stasis in 31 of 48 models and bevacizumab in 2 of 48. Based on statistical analysis, aflibercept was more active than bevacizumab in 39 of 48 models; in 9 of 39 of these models, bevacizumab was considered inactive. In 9 of 48 remaining models, aflibercept and bevacizumab had similar activity. Tumor levels of hVEGF-A (range 776-56,039 pg/mg total protein) were ∼16- to 1,777-fold greater than mVEGF-A (range 8-159 pg/mg total protein). Tumor levels of mPlGF (range 104-1,837 pg/mg total protein) were higher than hPlGF (range 0-543 pg/mg total protein) in 47 of 48 models. Tumor cells were the major source of VEGF; PlGF was primarily produced by tumor stroma. Because tumor levels of hVEGF-A were far greater than mVEGF-A, bevacizumab's inability to bind mVEGF-A is unlikely to explain higher and more consistent aflibercept activity. Neutralizing PlGF and VEGFR-1 activation may be a factor and should be investigated in future studies. In these colorectal cancer PDX models, aflibercept demonstrated greater antitumor activity than bevacizumab.


Assuntos
Anticorpos Monoclonais Humanizados/administração & dosagem , Neoplasias Colorretais/tratamento farmacológico , Sinergismo Farmacológico , Receptores de Fatores de Crescimento do Endotélio Vascular/administração & dosagem , Proteínas Recombinantes de Fusão/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Bevacizumab , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Terapia de Alvo Molecular , Fator de Crescimento Placentário , Proteínas da Gravidez/antagonistas & inibidores , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Langmuir ; 29(45): 13694-707, 2013 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-24111685

RESUMO

This paper presents a stochastic approach for the simulation of particle agglomeration, which is addressed as a two-step process: first, particles are transported by the flow toward each other (collision step) and, second, short-ranged particle-particle interactions lead either to the formation of an agglomerate or prevent it (adhesion step). Particle collisions are treated in the framework of Lagrangian approaches where the motions of a large number of particles are explicitly tracked. The key idea to detect collisions is to account for the whole continuous relative trajectory of particle pairs within each time step and not only the initial and final relative distances between two possible colliding partners at the beginning and at the end of the time steps. The present paper is thus the continuation of a previous work (Mohaupt M., Minier, J.-P., Tanière, A. A new approach for the detection of particle interactions for large-inertia and colloidal particles in a turbulent flow, Int. J. Multiphase Flow, 2011, 37, 746-755) and is devoted to an extension of the approach to the treatment of particle agglomeration. For that purpose, the attachment step is modeled using the DLVO theory (Derjaguin and Landau, Verwey and Overbeek) which describes particle-particle interactions as the sum of van der Waals and electrostatic forces. The attachment step is coupled with the collision step using a common energy balance approach, where particles are assumed to agglomerate only if their relative kinetic energy is high enough to overcome the maximum repulsive interaction energy between particles. Numerical results obtained with this model are shown to compare well with available experimental data on agglomeration. These promising results assert the applicability of the present modeling approach over a whole range of particle sizes (even nanoscopic) and solution conditions (both attractive and repulsive cases).

13.
Bioorg Med Chem Lett ; 23(3): 715-9, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23265898

RESUMO

Protein arginin deaminase 4 (PAD4) is a calcium dependent enzyme which catalyses the conversion of peptidyl-arginine into peptidyl-citrulline and is implicated in several diseases such as rheumatoid arthritis (RA) and cancer. Herein we report the discovery of novel small-molecule, non peptidic PAD4 inhibitors incorporating primary/secondary guanidine moieties.


Assuntos
Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Hidrolases/antagonistas & inibidores , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/química , Guanina/química , Humanos , Concentração Inibidora 50 , Modelos Moleculares , Estrutura Molecular , Proteína-Arginina Desiminase do Tipo 4 , Desiminases de Arginina em Proteínas
14.
Adv Colloid Interface Sci ; 185-186: 34-76, 2012 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-23141134

RESUMO

Particulate fouling generally arises from the continuous deposition of colloidal particles on initially clean surfaces, a process which can even lead to a complete blockage of the fluid cross-section. In the present paper, the initial stages of the fouling process (which include single-particle deposition and reentrainment) are first addressed and current modelling state-of-the-art for particle-turbulence and particle-wall interactions is presented. Then, attention is specifically focused on the later stages (which include multilayer formation, clogging and blockage). A detailed review of experimental works brings out the essential mechanisms occurring during these later stages: as for the initial stages, it is found that clogging results from the competition between particle-fluid, particle-surface and particle-particle interactions. Numerical models that have been proposed to reproduce the later stages of fouling are then assessed and a new Lagrangian stochastic approach to clogging in industrial cases is detailed. These models further confirm that, depending on hydrodynamical conditions (the flow velocity), fluid characteristics (such as the ionic strength) as well as particle and substrate properties (such as zeta potentials), particle deposition can lead to the formation of either a single monolayer or multilayers. The present paper outlines also future numerical developments and experimental works that are needed to complete our understanding of the later stages of the fouling process.

15.
Langmuir ; 28(1): 438-52, 2012 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-22107171

RESUMO

In this paper, the reentrainment of nanosized and microsized particles from rough walls under various electrostatic conditions and various hydrodynamic conditions (either in air or aqueous media) is numerically investigated. This issue arises in the general context of particulate fouling in industrial applications, which involves (among other phenomena) particle deposition and particle reentrainment. The deposition phenomenon has been studied previously and, in the present work, we focus our attention on resuspension. Once particles are deposited on a surface, the balance between hydrodynamic forces (which tend to move particles away from the surface) and adhesion forces (which maintain particles on the surface) can lead to particle removal. Adhesion forces are generally described using van der Waals attractive forces, but the limit of these models is that any dependence of adhesion forces on electrostatic forces (due to variations in pH or ionic strength) cannot be reproduced numerically. For this purpose, we develop a model of adhesion forces that is based on the DLVO (Derjaguin and Landau, Verwey and Overbeek) theory and which includes also the effect of surface roughness through the use of hemispherical asperities on the surface. We first highlight the effect of the curvature radius on adhesion forces. Then some numerical predictions of adhesion forces or adhesion energies are compared to experimental data. Finally, the overall effects of surface roughness and electrostatic forces are demonstrated with some applications of the complete reentrainment model in some simple test cases.

16.
Langmuir ; 27(8): 4603-12, 2011 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-21405065

RESUMO

In this paper, we investigate the deposition of nanosized and microsized particles on rough surfaces under electrostatic repulsive conditions in an aqueous suspension. This issue arises in the general context of modeling particle deposition which, in the present work, is addressed as a two-step process: first particles are transported by the motions of the flow toward surfaces and, second, in the immediate vicinity of the walls, the forces between the incoming particles and the walls are determined using the classical DLVO theory. The interest of this approach is to take into account both hydrodynamical and physicochemical effects within a single model. Satisfactory results have been obtained in attractive conditions but some discrepancies have been revealed in the case of repulsive conditions, in line with other studies which have noted differences between predictions based on the DLVO theory and experimental measurements for similar repulsive conditions. Consequently, the aim of the present work is to focus on this particular range and, more specifically, to assess the influence of surface roughness on the DLVO potential energy. For this purpose, we introduce a new simplified model of surface roughness where spherical protruding asperities are placed randomly on a smooth plate. On the basis of this geometrical description, approximate DLVO expressions are used and numerical calculations are performed. We first highlight the existence of a critical asperity size which brings about the highest reduction of the DLVO interaction energy. Then, the influence of the surface covered by the asperities is investigated as well as retardation effects which can play a role in the reduction of the interaction energy. Finally, by considering the random distribution of the energy barrier of the DLVO potential due to the random geometrical configurations, the overall effect of surface roughness is demonstrated with one application of the complete deposition model in an industrial test case. These new numerical results show that nonzero deposition rates are now obtained even in repulsive conditions, which confirms that surface roughness is a relevant aspect to introduce in general approaches to deposition.

17.
J Org Chem ; 74(5): 1932-8, 2009 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-19175330

RESUMO

A straightforward approach to novel (5-nitropyridin-2-yl)alkyl and (5-nitropyridin-3-yl)alkyl carbamate building blocks is presented in this study. Their construction is achieved by condensation of N-carbamate alpha- and beta-amino carbonyl derivatives with 1-methyl-3,5-dinitro-2-pyridone 1 under microwave irradiation. Judiciously chosen modifications in the nature of the parent carbonyl starting material has influenced the regiochemical outcome of the reaction and allowed an efficient access to novel nitrogen-containing scaffolds. Compounds sharing morphological similarities have been gathered in three libraries differing from each other in a single structural parameter.


Assuntos
Carbamatos/síntese química , Micro-Ondas , Piridinas/química , Carbamatos/química , Ciclização , Estrutura Molecular , Estereoisomerismo
18.
Crit Care ; 9(6): R631-5, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16280064

RESUMO

INTRODUCTION: Central venous catheterization is commonly used in critically ill patients and may cause different complications, including infection. Although there are many studies about CVC-related infection, very few have analyzed it in detail. The objective of this study was to analyze the incidence of catheter-related local infection (CRLI) and catheter-related bloodstream infection (CRBSI) with central venous catheters (CVCs) according to different access sites. METHODS: This is a prospective and observational study, conducted in a 24-bed medical surgical intensive care unit of a 650-bed university hospital. All consecutive patients admitted to the ICU during 3 years (1 May 2000 and 30 April 2003) were included. RESULTS: The study included 2,018 patients. The number of CVCs and days of catheterization duration were: global, 2,595 and 18,999; subclavian, 917 and 8,239; jugular, 1,390 and 8,361; femoral, 288 and 2,399. CRLI incidence density was statistically higher for femoral than for jugular (15.83 versus 7.65, p < 0.001) and subclavian (15.83 versus 1.57, p < 0.001) accesses, and higher for jugular than for subclavian access (7.65 versus 1.57, p < 0.001). CRBSI incidence density was statistically higher for femoral than for jugular (8.34 versus 2.99, p = 0.002) and subclavian (8.34 versus 0.97, p < 0.001) accesses, and higher for jugular than for subclavian access (2.99 versus 0.97, p = 0.005). CONCLUSION: Our results suggest that the order for punction, to minimize the CVC-related infection risk, should be subclavian (first order), jugular (second order) and femoral vein (third order).


Assuntos
Infecções Bacterianas/epidemiologia , Candidíase/epidemiologia , Cateterismo Venoso Central/efeitos adversos , Cateterismo Venoso Central/estatística & dados numéricos , Infecções Bacterianas/microbiologia , Candidíase/microbiologia , Cateteres de Demora/efeitos adversos , Feminino , Veia Femoral , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Positivas/epidemiologia , Humanos , Incidência , Unidades de Terapia Intensiva/estatística & dados numéricos , Veias Jugulares , Tempo de Internação/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Micoses/epidemiologia , Estudos Prospectivos , Espanha/epidemiologia , Veia Subclávia , Análise de Sobrevida
19.
Chest ; 128(2): 595-601, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16100143

RESUMO

OBJECTIVE: To determine prolonged intubation rates among patients undergoing coronary artery bypass graft (CABG) surgery, and to evaluate the ability of the Intensive Care Unit Risk Stratification Score (ICURSS) model to predict these events. DESIGN: Prospective observational study. SETTING: A 24-bed ICU in a tertiary referral university hospital. PATIENTS: Five hundred sixty-nine patients undergoing CABG surgery. INTERVENTIONS: Variables of the ICURSS model were recorded at ICU admission. Extubation was performed according to a standard protocol. Patients remaining intubated within 8 h after ICU admission were designated as having early extubation failure (EEF). The next evaluations at 16, 24, 48, 72, and 96 h designated patients as having a prolonged intubation period (PIP) and prolonged mechanical ventilation (PMV) for 24, 48, 72, and 96 h. The ability of the ICURSS model to predict extubation failure at different cutoff values was measured using the Hosmer-Lemeshow goodness-of-fit test and the area under the receiver operating characteristic curve. MEASUREMENTS AND RESULTS: Prolonged intubation rates were as follows: EEF, 40.2%; PIP, 17.2%; PMV for 24 h, 10.4%; PMV for 48 h, 7.6%; PMV for 72 h, 6.5%; and PMV for 96 h, 6.0%. At every cutoff, the ICURSS showed poor discrimination to predict the failure to be extubated. Calibration was also poor, although some ability to predict both EEF and PMV at > or = 48 h was shown. CONCLUSIONS: Prolonged intubation rates after undergoing CABG surgery in our setting were comparable with those of other reports from institutions where fast-track cardiac anesthesia is currently in practice. In our cohort, the ICURSS was not useful for the prediction of length of intubation.


Assuntos
Ponte de Artéria Coronária , Unidades de Terapia Intensiva , Intubação Intratraqueal/estatística & dados numéricos , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Medição de Risco , Fatores de Tempo
20.
J Med Chem ; 47(17): 4178-87, 2004 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-15293990

RESUMO

A novel and highly efficient flexible docking approach is presented where the conformations (internal degrees of freedom) and orientations (external degrees of freedom) of the ligands are successively considered. This hybrid method takes advantage of the synergistic effects of structure-based and ligand-based drug design techniques. Preliminary antagonist-derived pharmacophore determination provides the postulated bioactive conformation. Subsequent docking of this pharmacophore to the receptor crystal structure results in a postulated pharmacophore/receptor binding mode. Pharmacophore-oriented docking of antagonists is subsequently achieved by matching ligand interacting groups with pharmacophore points. Molecular dynamics in water refines the proposed complexes. To validate the method, arginine-glycine-aspartic acid (RGD) containing peptides, pseudopeptides, and RGD-like antagonists were docked to the crystal structure of alphavbeta3 holoprotein and apoprotein. The proposed directed docking was found to be more accurate, faster, and less biased with respect to the protein structure (holo and apoprotein) than DOCK, Autodock, and FlexX docking methods. The successful docking of an antagonist recently cocrystallized with the receptor to both apo and holoprotein is particularly appealing. The results summarized in this report illustrated the efficiency of our light CoMFA/rigid body docking hybrid method.


Assuntos
Integrina alfaVbeta3/química , Modelos Biológicos , Modelos Moleculares , Oligopeptídeos/química , Apoproteínas/química , Sítios de Ligação , Cristalografia por Raios X , Integrina alfaVbeta3/antagonistas & inibidores , Ligantes , Conformação Molecular , Estrutura Molecular , Ligação Proteica , Relação Quantitativa Estrutura-Atividade
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