20 research outputs found
Tyrosine kinases inhibition by Imatinib slows progression in chronic anti-thy1 glomerulosclerosis of the rat
The effects of gold nanoparticles functionalized with Ă-amyloid specific peptides on an in vitro model of blood-brain barrier
© 2017 Elsevier Inc. We studied the effect of gold nanoparticle (AuNP) size, surface charge, concentration and morphology on the integrity of the bloodâbrain barrier (BBB) in a well-established in vitro model set-up. We focused on the effect of peptide functionalized hollow gold nanospheres and gold nanorods, which selectively bind to amyloidogenic ÎČ-amyloid structures. These AuNP conjugates have already been successfully tested as photothermal absorbers for potential application in Alzheimer's disease (AD) therapy in an in vitro set-up, but may exhibit a low passage through the BBB due to their overall negative charge. Our results show that: (i) small (1.4 nm) AuNPs strongly affects the BBB integrity, (ii) negative surface charge impedes BBB passage, and (iii) this charge effect caused by the peptide is compensated by covalent coupling to a polyethylene glycol ligand stabilizing the particles in diluted manner
Activation of PPARÎł reverses a defect of surfactant synthesis in mice lacking two types of fatty acid binding protein
Lung surfactant is a lipid-protein-film covering the inner alveolar surface. We have previously shown that double knock-out (d-ko) mice lacking both the epidermal-type (E-) and the heart-type (H-) fatty acid binding protein (FABP) exhibit a defect of surfactant synthesis in alveolar type II cells that can be corrected by feeding pioglitazone, a drug that activates peroxisome proliferator-activated receptor gamma (PPARÎł). Here, we demonstrate first that healthy surfactant at collapse pressure produces protrusions composed of bilayers but not folds, second that the d-ko effect profoundly perturbs lipid/hydrophobic protein composition, pressure-area isotherm, and structural organisation of the surfactant at nanoscale, parameters that are critical for the normal breathing cycle. In support of these data in vivo measurements of lung function reveal that maximum compliance in d-ko vs. wild-type mice is significantly reduced. Further, we show that the biophysical phenotype can be corrected substantially with pioglitazone. Finally, we show that d-ko alveolar cells up-regulate liver-type (L-) FABP, a member of the FABP family that we have previously shown to interact with PPARÎł. Taken together, these data suggest that PPARÎł agonists could be a tool to repair surfactant damage caused by dysfunctional alveolar lipid metabolism, and provide in vivo support for L-FABP aided signaling
3D Molecular ToF-SIMS Imaging of Artificial Lipid Membranes Using a Discriminant Analysis-Based Algorithm
Artificial
lipid membranes play a growing role in technical applications
such as biosensors in pharmacological research and as model systems
in the investigation of biological lipid films. In the standard procedure
for displaying the distribution of membrane components, fluorescence
microscopy, the fluorophores used can influence the distribution of
the components and usually not all substances can be displayed at
the same time. The discriminant analysis-based algorithm used in combination
with scanning time-of-flight secondary ion mass spectrometry (ToF-SIMS)
enables marker-free, quantitative, simultaneous recording of all membrane
components. These data are used for reconstruction of distribution
patterns. In the model system used for this survey, a tear fluid lipid
layer, the distribution patterns of all lipids correlate well in calculated
ToF-SIMS images and epi-fluorescence microscopic images. All epi-fluorescence
microscopically viewable structures are visible when using both positive
and negative secondary ions and can be reproduced with high lateral
resolution in the submicrometer range despite the very low signal
intensity and a very low signal-to-noise ratio. In addition, three-dimensional
images can be obtained with a subnanometer depth resolution. Furthermore,
structures and the distribution of substances that cannot be made
visible by epi-fluorescence microscopy can be displayed. This enables
new insights that cannot be gained by epi-fluorescence microscopy
alone
3D Molecular ToF-SIMS Imaging of Artificial Lipid Membranes Using a Discriminant Analysis-Based Algorithm
Artificial
lipid membranes play a growing role in technical applications
such as biosensors in pharmacological research and as model systems
in the investigation of biological lipid films. In the standard procedure
for displaying the distribution of membrane components, fluorescence
microscopy, the fluorophores used can influence the distribution of
the components and usually not all substances can be displayed at
the same time. The discriminant analysis-based algorithm used in combination
with scanning time-of-flight secondary ion mass spectrometry (ToF-SIMS)
enables marker-free, quantitative, simultaneous recording of all membrane
components. These data are used for reconstruction of distribution
patterns. In the model system used for this survey, a tear fluid lipid
layer, the distribution patterns of all lipids correlate well in calculated
ToF-SIMS images and epi-fluorescence microscopic images. All epi-fluorescence
microscopically viewable structures are visible when using both positive
and negative secondary ions and can be reproduced with high lateral
resolution in the submicrometer range despite the very low signal
intensity and a very low signal-to-noise ratio. In addition, three-dimensional
images can be obtained with a subnanometer depth resolution. Furthermore,
structures and the distribution of substances that cannot be made
visible by epi-fluorescence microscopy can be displayed. This enables
new insights that cannot be gained by epi-fluorescence microscopy
alone
In vitro models of the bloodâbrain barrier: An overview of commonly used brain endothelial cell culture models and guidelines for their use
The endothelial cells lining the brain capillaries separate the blood from the brain parenchyma. The endothelial monolayer of the brain capillaries serves both as a crucial interface for exchange of nutrients, gases, and metabolites between blood and brain, and as a barrier for neurotoxic components of plasma and xenobiotics. This âblood-brain barrierâ function is a major hindrance for drug uptake into the brain parenchyma. Cell culture models, based on either primary cells or immortalized brain endothelial cell lines, have been developed, in order to facilitate in vitro studies of drug transport to the brain and studies of endothelial cell biology and pathophysiology. In this review, we aim to give an overview of established in vitro bloodâbrain barrier models with a focus on their validation regarding a set of well-established bloodâbrain barrier characteristics. As an ideal cell culture model of the bloodâbrain barrier is yet to be developed, we also aim to give an overview of the advantages and drawbacks of the different models described
Blood-brain barrier in vitro models and their application in toxicology
International audienc
Fluorescent Modular Boron Systems Based on NNN- and ONO-Tridentate Ligands:Self-Assembly and Cell Imaging
<p>We have synthesized a series of new fluorescent boron systems 1a-c and 2a-d based on nitrogen (NNN) or nitrogen and oxygen (ONO)-containing tridentate ligands. These novel dyes are characterized by high thermal and chemical stability. They show large Stokes shifts (mostly above 3200 cm(-1)) and quantum yields in solution and in the solid state up to 40%. The easy, modular synthesis facilitates the convenient variation of the axial substituent on the central boron atom, allowing the functionalization of this dye for biochemical use. Introducing a long alkyl chain with a phenyl spacer at this axial position enables the self-assembly of the boron compound 2d to form a fluorescent vesicle, which is able to encapsulate small molecules such as sulforhodamine. Additionally, boron compound 2d was found to serve as a dye for cell imaging since it has the capability of binding to the nuclear membranes of HeLa cells. With phospholipids such as DOPC, giant unilamelar vesicles (GUV) are formed. These results demonstrate the wide applicability of this new boron system in supramolecular and medicinal chemistry.</p>
Fluorescent Modular Boron Systems Based on NNN- and ONO-Tridentate Ligands: Self-Assembly and Cell Imaging
We
have synthesized a series of new fluorescent boron systems <b>1a</b>â<b>c</b> and <b>2a</b>â<b>d</b> based
on nitrogen (NNN) or nitrogen and oxygen (ONO)-containing
tridentate ligands. These novel dyes are characterized by high thermal
and chemical stability. They show large Stokes shifts (mostly above
3200 cm<sup>â1</sup>) and quantum yields in solution and in
the solid state up to 40%. The easy, modular synthesis facilitates
the convenient variation of the axial substituent on the central boron
atom, allowing the functionalization of this dye for biochemical use.
Introducing a long alkyl chain with a phenyl spacer at this axial
position enables the self-assembly of the boron compound <b>2d</b> to form a fluorescent vesicle, which is able to encapsulate small
molecules such as sulforhodamine. Additionally, boron compound <b>2d</b> was found to serve as a dye for cell imaging since it has
the capability of binding to the nuclear membranes of HeLa cells.
With phospholipids such as DOPC, giant unilamelar vesicles (GUV) are
formed. These results demonstrate the wide applicability of this new
boron system in supramolecular and medicinal chemistry