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1.
Phys Chem Chem Phys ; 18(25): 16812-21, 2016 Jun 22.
Article in English | MEDLINE | ID: mdl-27279359

ABSTRACT

Sugar-responsive microgels were prepared by the covalent grafting of a poly(N-isopropylacrylamide) (pNIPAM) matrix with phenylboronic acid (PBA) as a saccharide sensing unit and a [Ru(bpy)3](2+) derivative (2,2'-bipyridine) as a luminescent reporter. Time-resolved emission studies reveal that the ruthenium complex has an unusually long lifetime (1.6 µs) and high quantum yield (∼0.17) in the PBA-microgel environment. In the presence of sugars, the microgels swell due to the formation of a sugar-boronate ester, leading to a more hydrophilic polymer chain. The swelling is accompanied by a decrease of the lifetime and the photoluminescence quantum yield, which cannot be explained solely by the swelling of the hydrogel. The emission properties of the ruthenium complex in PBA-functionalized microgels are compared to those in pNIPAM microgels lacking PBA moieties in various swelling states. The presence of PBA in the vicinity of [Ru(bpy)3](2+) is shown to have a predominant impact on its luminescence properties, mainly through a decrease of the polarity. Sugar-induced triggering of the boronate state thus leads to strong variations of the polarity and the luminescence characteristics.

2.
Arterioscler Thromb Vasc Biol ; 33(3): 605-11, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23288162

ABSTRACT

OBJECTIVE: Flow- (shear stress-)mediated outward remodeling of resistance arteries is involved in collateral growth during postischemic revascularization. As this remodeling is especially important during pregnancy, we hypothesized that estrogens may be involved. A surgical model eliciting a local increase in blood flow in 1 mesenteric resistance artery was used in 3-month-old ovariectomized female rats either treated with 17-ß-estradiol (E2) or left untreated. METHODS AND RESULTS: After 14 days, arterial diameter was greater in high-flow arteries than in normal-flow vessels. An ovariectomy suppressed high-flow remodeling, while E2 restored it. High-flow remodeling was absent in mice lacking the estrogen receptor α but not estrogen receptor ß. The kinetics of inflammatory marker expression, macrophage infiltration, oxidative stress, and metaloproteinases expression were not altered by the absence of E2 after 2 and 4 days, that is, during remodeling. Nevertheless, E2 was required for the increase in endothelial nitric oxide synthase expression and activation at day 4 when diameter expansion occurs. Finally, the impact of E2 on the endothelium appeared crucial for high-flow remodeling, as this E2 action was abrogated in mice lacking endothelial NOS, as well as in Tie2-Cre(+) ERα(f/f) mice. CONCLUSIONS: We demonstrate the essential role of E2 and endothelial estrogen receptor α in flow-mediated remodeling of resistance arteries in vivo.


Subject(s)
Endothelial Cells/metabolism , Estradiol/administration & dosage , Estrogen Receptor alpha/agonists , Estrogen Replacement Therapy , Mesenteric Arteries/drug effects , Vascular Resistance/drug effects , Animals , Blood Pressure/drug effects , Caveolin 1/metabolism , Endothelial Cells/drug effects , Estrogen Receptor alpha/deficiency , Estrogen Receptor alpha/genetics , Estrogen Receptor beta/deficiency , Estrogen Receptor beta/genetics , Female , Mesenteric Arteries/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Nitric Oxide/metabolism , Nitric Oxide Synthase Type III/deficiency , Nitric Oxide Synthase Type III/genetics , Ovariectomy , Phosphorylation , Rats , Rats, Wistar , Regional Blood Flow/drug effects , Splanchnic Circulation/drug effects , Time Factors , Vasodilation/drug effects
3.
Perfusion ; 26(2): 91-8, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21173036

ABSTRACT

The role of complement activation on the cerebral vasculature after cardiopulmonary bypass (CPB) is unclear. The goal of the study was to assess whether heparin-coated CPB reduces complement activation, and influences cerebral blood flow velocities (CBFV). Twenty-four patients undergoing coronary surgery were randomly allocated to non-coated (NC-group) or heparin-coated (HC-group) CPB. Complement activation was assessed by measuring sC5b-9. Transcranial Doppler (TCD) was performed on middle cerebral arteries before and after CPB. Systolic (SV), diastolic (DV) and mean (MV) CBFV were measured. Significant increase of sC5b-9 (p=0.003) was observed in the NC-group and CBFV increased after CPB (SV by 27%, p=0.05; DV by 40%, p=0.06; MV by 33%, p=0.04) whereas no changes were detected in the HC-group. TCD values were higher in the NC-group than in the HC-group (SV, p=0.04; DV, p=0.03; MV, p=0.03) although cardiac index, systemic vascular resistance, haematocrit and pCO(2) were similar. Postoperative SV, DV and MV were significantly correlated with sC5b-9 (r=0.583, p=0.009; r=0.581, p=0.009; r=0.598, p=0.007, respectively). Increased CBFV after CPB are correlated to the level of complement activation and may be controlled by heparin-coated circuits.


Subject(s)
Brain/blood supply , Brain/physiopathology , Cardiopulmonary Bypass/methods , Complement Activation/drug effects , Heparin/pharmacology , Aged , Blood Flow Velocity/drug effects , Brain/immunology , Humans , Middle Aged , Ultrasonography, Doppler, Transcranial
4.
Ann Fr Anesth Reanim ; 28(4): 291-6, 2009 Apr.
Article in French | MEDLINE | ID: mdl-19299103

ABSTRACT

OBJECTIVES: Insertion of Swan-Ganz catheter for a few days may be necessary in cardiac surgery. This study was aimed at determining the incidence and the evolution of thrombotic images within the internal jugular vein as well as assessing their association with the presence of a prolonged fever at postoperative day 7 in the lack of any documented infection. MATERIAL AND METHODS: All the patients undergoing cardiac surgery had a two-dimensional ultrasonography of internal jugular veins preoperatively, at discharge (day 7) and at postoperative day 90 if thrombotic images were seen at day 7. RESULTS: Sleeve-like and compact thrombotic images have been observed in site of venipuncture in 52 patients (70.3%). None had any residual thrombotic image 90 days after the operation. No clinical thromboembolic migration has been observed. There was no statistical association between the presence of a thrombotic image at the ultrasonography and the duration of catheterization. Moreover, there was no association between the anticoagulation before, during and after the surgery and the presence of a thrombotic image. We found a non-significant association between fever at day 7 and the presence of a thrombotic image within the internal jugular vein. CONCLUSION: Thrombotic images in the internal jugular vein after catheterization are frequent and disappear at day 90. The limited sample size of this study does not provide strong evidence of the role of jugular thrombi in the prolongation of fever after cardiac surgery.


Subject(s)
Cardiac Surgical Procedures , Catheterization, Swan-Ganz/adverse effects , Jugular Veins/diagnostic imaging , Venous Thrombosis/etiology , Aged , Aged, 80 and over , Anticoagulants/administration & dosage , Anticoagulants/therapeutic use , Cardiac Catheterization/instrumentation , Disease Progression , Extracorporeal Circulation , Female , Fever/etiology , Humans , Incidence , Infections/complications , Jugular Veins/injuries , Male , Middle Aged , Monitoring, Intraoperative/instrumentation , Postoperative Complications , Postoperative Period , Remission, Spontaneous , Retrospective Studies , Ultrasonography , Venous Thrombosis/diagnostic imaging , Venous Thrombosis/epidemiology
5.
Arterioscler Thromb Vasc Biol ; 28(12): 2216-24, 2008 Dec.
Article in English | MEDLINE | ID: mdl-18818417

ABSTRACT

OBJECTIVE: Notch3, a member of the evolutionary conserved Notch receptor family, is primarily expressed in vascular smooth muscle cells. Genetic studies in human and mice revealed a critical role for Notch3 in the structural integrity of distal resistance arteries by regulating arterial differentiation and postnatal maturation. METHODS AND RESULTS: We investigated the role of Notch3 in vascular tone in small resistance vessels (tail and cerebral arteries) and large (carotid) arteries isolated from Notch3-deficient mice using arteriography. Passive diameter and compliance were unaltered in mutant arteries. Similarly, contractions to phenylephrine, KCl, angiotensin II, and thromboxane A2 as well as dilation to acetylcholine or sodium nitroprusside were unaffected. However, Notch3 deficiency induced a dramatic reduction in pressure-induced myogenic tone associated with a higher flow (shear stress)-mediated dilation in tail and cerebral resistance arteries only. Furthermore, RhoA activity and myosin light chain phosphorylation, measured in pressurized tail arteries, were significantly reduced in Notch3KO mice. Additionally, myogenic tone inhibition by the Rho kinase inhibitor Y27632 was attenuated in mutant tail arteries. CONCLUSIONS: Notch3 plays an important role in the control of vascular mechano-transduction, by modulating the RhoA/Rho kinase pathway, with opposite effects on myogenic tone and flow-mediated dilation in the resistance circulation.


Subject(s)
Arteries/physiology , Cerebral Arteries/physiology , Receptors, Notch/physiology , Vascular Resistance/physiology , Acetylcholine/pharmacology , Amides/pharmacology , Animals , Arteries/drug effects , Arteries/pathology , Arteries/physiopathology , Cerebral Arteries/drug effects , Cerebral Arteries/pathology , Cerebral Arteries/physiopathology , Enzyme Inhibitors/pharmacology , Male , Mice , Mice, Knockout , Phenylephrine/pharmacology , Pyridines/pharmacology , Receptor, Notch3 , Receptors, Notch/deficiency , Receptors, Notch/genetics , Tail/blood supply , Vascular Resistance/drug effects , Vascular Resistance/genetics , Vasoconstriction/drug effects , Vasoconstriction/genetics , Vasoconstriction/physiology , Vasodilation/drug effects , Vasodilation/genetics , Vasodilation/physiology , rho GTP-Binding Proteins/metabolism , rho-Associated Kinases/antagonists & inhibitors , rhoA GTP-Binding Protein
6.
Ann Fr Anesth Reanim ; 25(5): 510-20, 2006 May.
Article in French | MEDLINE | ID: mdl-16488106

ABSTRACT

The systemic inflammatory response in cardiac surgery is closely related to the haemostasis disturbances. It is responsible of a significant morbidity and mortality that was previously suspected to be caused by cardiopulmonary bypass alone. However, it is time now to clearly identify the factors that are material-dependent from that material-independent. From this point of view, off-pump surgery allowed for better comprehension of the multiple sources of the inflammatory response. Numerous pathways are activated, involving complement, platelets, neutrophiles and monocytes. The tissue pathway of the coagulation system, through tissue factor, is of major importance and has to be surgically considered in order to reduce the whole body inflammatory response postoperatively. The quality of the extracorporeal perfusion through its consequences on organ perfusion, particularly in the splanchnic area, also participates to this pathophysiological process. Beyond the progress of technology provided by the industry, particularly the minimally extracorporeal circulation derived from off-pump surgery evolution, the surgical approach is of major importance in the control of the systemic inflammatory response and must not be ignored yet.


Subject(s)
Blood Coagulation Disorders/etiology , Cardiac Surgical Procedures , Cardiopulmonary Bypass/adverse effects , Intraoperative Complications/etiology , Postoperative Complications/etiology , Systemic Inflammatory Response Syndrome/etiology , Anesthetics/adverse effects , Anticoagulants/adverse effects , Anticoagulants/therapeutic use , Biocompatible Materials/adverse effects , Blood Coagulation Disorders/prevention & control , Cardiopulmonary Bypass/instrumentation , Cardiopulmonary Bypass/methods , Complement Activation , Coronary Artery Bypass, Off-Pump/adverse effects , Cytokines/physiology , Endotoxins/adverse effects , Equipment Contamination , Equipment Design , Genetic Predisposition to Disease , Heparin/adverse effects , Heparin/therapeutic use , Humans , Inflammation/etiology , Intraoperative Complications/prevention & control , Myocardial Reperfusion Injury/etiology , Postoperative Complications/prevention & control , Protamines/adverse effects , Protamines/therapeutic use , Splanchnic Circulation , Systemic Inflammatory Response Syndrome/prevention & control
7.
Article in English | MEDLINE | ID: mdl-29449756

ABSTRACT

We have recently developed a wide-field photon-counting detector (the H33D detector) having high-temporal and high-spatial resolutions and capable of recording up to 500,000 photons per sec. Its temporal performance has been previously characterized using solutions of fluorescent materials with different lifetimes, and its spatial resolution using sub-diffraction objects (beads and quantum dots). Here we show its application to fluorescence lifetime imaging of live cells and compare its performance to a scanning confocal TCSPC approach. With the expected improvements in photocathode sensitivity and increase in detector throughput, this technology appears as a promising alternative to the current lifetime imaging solutions.

8.
Science ; 307(5709): 538-44, 2005 Jan 28.
Article in English | MEDLINE | ID: mdl-15681376

ABSTRACT

Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near-infrared emission during surgery. The new generations of qdots have far-reaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.


Subject(s)
Cell Physiological Phenomena , Diagnostic Imaging , Diagnostic Techniques and Procedures , Quantum Dots , Animals , Fluorescence , Humans , Molecular Probes
9.
Article in English | MEDLINE | ID: mdl-29176922

ABSTRACT

We have developed a new functionalization approach for semiconductor nanocrystals based on a single-step exchange of surface ligands with custom-designed peptides. This peptide-coating technique yield small, monodisperse and very stable water-soluble NCs that remain bright and photostable. We have used this approach on several types of core and core-shell NCs in the visible and near-infrared spectrum range and used fluorescence correlation spectroscopy for rapid assessment of the colloidal and photophysical properties of the resulting particles. This peptide coating strategy has several advantages: it yields probes that are immediately biocompatible; it is amenable to improvements of the different properties (solubilization, functionalization, etc) via rational design, parallel synthesis, or molecular evolution; it permits the combination of several functions on individual NCs. These functionalized NCs have been used for diverse biomedical applications. Two are discussed here: single-particle tracking of membrane receptor in live cells and combined fluorescence and PET imaging of targeted delivery in live animals.

10.
Discov Med ; 5(26): 213-8, 2005 Apr.
Article in English | MEDLINE | ID: mdl-20704913

ABSTRACT

Extract: The past few decades have witnessed technical advances that have introduced cell biologists and physicians to a new, dynamic, subcellular world where genes and gene products can be visualized to interact in space and time and in health and disease. The accelerating field of molecular imaging has been critically dependent on indicator probes which show when and where genetically or biochemically defined molecules, signals or processes appear, interact and disappear, with high spatial and temporal resolution in living cells and whole organisms. For example, the use of radionuclide tracers combined with 3-dimensional (3-D) imaging systems such as Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) are now helping clinicians to characterize the molecular status of tumors deep within patients. Other types of imaging probes rely on the bioluminescence and fluorescence of genetically encoded proteins (originally found in fireflies and jellyfish, respectively) or entirely synthetic fluorochromes, or a combination of both. New powerful biological fluorescence microscopes provide the ability to study single molecules within single cells. Multiphoton confocal microscopy has been developed to allow for the capturing of high-resolution, 3-D images of living tissues that have been tagged with highly specific fluorophores.

11.
Opt Lett ; 26(11): 825-7, 2001 Jun 01.
Article in English | MEDLINE | ID: mdl-18040463

ABSTRACT

The long (but not too long) fluorescence lifetime of CdSe semiconductor quantum dots was exploited to enhance fluorescence biological imaging contrast and sensitivity by time-gated detection. Significant and selective reduction of the autofluorescence contribution to the overall image was achieved, and enhancement of the signal-to-background ratio by more than an order of magnitude was demonstrated.

12.
Proc Natl Acad Sci U S A ; 97(17): 9461-6, 2000 Aug 15.
Article in English | MEDLINE | ID: mdl-10931959

ABSTRACT

An optical ruler based on ultrahigh-resolution colocalization of single fluorescent probes is described in this paper. It relies on the use of two unique families of fluorophores, namely energy-transfer fluorescent beads (TransFluoSpheres) and semiconductor nanocrystal quantum dots, that can be excited by a single laser wavelength but emit at different wavelengths. A multicolor sample-scanning confocal microscope was constructed that allows one to image each fluorescent light emitter, free of chromatic aberrations, by scanning the sample with nanometer scale steps with a piezo-scanner. The resulting spots are accurately localized by fitting them to the known shape of the excitation point-spread function of the microscope. We present results of two-dimensional colocalization of TransFluoSpheres (40 nm in diameter) and of nanocrystals (3-10 nm in diameter) and demonstrate distance-measurement accuracy of better than 10 nm using conventional far-field optics. This ruler bridges the gap between fluorescence resonance energy transfer, near- and far-field imaging, spanning a range of a few nanometers to tens of micrometers.


Subject(s)
Fluorescent Dyes/metabolism , Molecular Probe Techniques/instrumentation , Color , Energy Transfer , Fluorescence , Microscopy, Confocal/instrumentation , Microscopy, Confocal/methods , Sensitivity and Specificity
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