The hydrophobic region of the Leishmania peroxin 14 : requirements for association with a glycosome mimetic membrane

This work was funded by operating grants from the Canadian Institutes of Health Research (CIHR) and a Natural Sciences Engineering Research Council of Canada (NSERC) Discovery grant [Fonds de recherche du Québec — Nature et technologies (FRQNT) Regroupement Stratégique grant to the Centre for Host-Parasite Interactions (A.J.)]. N.C. was supported by a doctoral research scholarship from FRQNT. E.B. was supported by a Banting postdoctoral fellowship from CIHR. This work was also supported in part by Wellcome Trust grants [086658 and 093228] to T.K.S. C.S. recognizes the financial support from the Natural Sciences and Engineering Research Council of Canada and a Canada Foundation for Innovation grant [16299].Protein import into the Leishmania glycosome requires docking of the cargo-loaded peroxin 5 (PEX5) receptor to the peroxin 14 (PEX14) bound to the glycosome surface. To examine the LdPEX14-membrane interaction, we purified L. donovani promastigote glycosomes and determined the phospholipid and fatty acid composition. These membranes contained predominately phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol (PG) modified primarily with C18 and C22 unsaturated fatty acid. Using large unilamellar vesicles (LUVs) with a lipid composition mimicking the glycosomal membrane in combination with sucrose density centrifugation and fluorescence-activated cell sorting technique, we established that the LdPEX14 membrane-binding activity was dependent on a predicted transmembrane helix found within residues 149-179. Monolayer experiments showed that the incorporation of PG and phospholipids with unsaturated fatty acids, which increase membrane fluidity and favor a liquid expanded phase, facilitated the penetration of LdPEX14 into biological membranes. Moreover, we demonstrated that the binding of LdPEX5 receptor or LdPEX5-PTS1 receptor-cargo complex was contingent on the presence of LdPEX14 at the surface of LUVs.PostprintPeer reviewe

Synthèse et optimisation de dendrimères et de nanoparticules d'or en vue d'applications biomédicales

Plusieurs substrats issus de la chimie organique, inorganique et organométallique ont été synthétisés et fonctionnalisés avec différents groupes chimiques, notamment des polyethylene glycol qui leur permet d’améliorer leur solubilité dans l’eau et de les rendre biocompatible pour une éventuelle application dans le milieu biomédical. Ces substrats sont des dendrimères synthétisés sur plusieurs générations, des polymères obtenus soit par polymérisation d’un dendron soit par dendronisation d’un polymère, ou encore des nanoparticules d’or qui peuvent être stabilisées par des ligands thiolates ou bien par des dendrimères de manière intra- ou inter-dendritique. Ces nano-objets ont été designés dans l’objectif d’encapsuler, de stabiliser ou d’améliorer différentes molécules biologiques telles que des vitamines (vitamine C, B3 et B6), des neurotransmetteurs (acétylcholine et dopamine) ou des agents anti-cancéreux (daunorubicine).Several substrates resulting from the organic, inorganic and organometallic chemistry were synthesized and functionalized with various chemical groups, including polyethylene glycol which enables them to improve their water solubility and to make them biocompatible for a possible application in the biomedical field. These substrates are dendrimers synthesized for several generations, polymers obtained either by polymerization of a dendron or by dendronization of a polymer, or gold nanoparticules which can be stabilized by thiolate ligands or by dendrimers in an intra- or inter-dendritic way. These nano-objects were designed with the aim of encapsulating, stabilizing or improving various biological molecules such as vitamins (vitamin C, B3 and B6), neurotransmitters (acetylcholine and dopamine) or anti-cancerous agents (daunorubicine)

Synthèse et optimisation de dendrimères et de nanoparticules d'or en vue d'applications biomédicales

Plusieurs substrats issus de la chimie organique, inorganique et organométallique ont été synthétisés et fonctionnalisés avec différents groupes chimiques, notamment des polyethylene glycol qui leur permet d’améliorer leur solubilité dans l’eau et de les rendre biocompatible pour une éventuelle application dans le milieu biomédical. Ces substrats sont des dendrimères synthétisés sur plusieurs générations, des polymères obtenus soit par polymérisation d’un dendron soit par dendronisation d’un polymère, ou encore des nanoparticules d’or qui peuvent être stabilisées par des ligands thiolates ou bien par des dendrimères de manière intra- ou inter-dendritique. Ces nano-objets ont été designés dans l’objectif d’encapsuler, de stabiliser ou d’améliorer différentes molécules biologiques telles que des vitamines (vitamine C, B3 et B6), des neurotransmetteurs (acétylcholine et dopamine) ou des agents anti-cancéreux (daunorubicine).Several substrates resulting from the organic, inorganic and organometallic chemistry were synthesized and functionalized with various chemical groups, including polyethylene glycol which enables them to improve their water solubility and to make them biocompatible for a possible application in the biomedical field. These substrates are dendrimers synthesized for several generations, polymers obtained either by polymerization of a dendron or by dendronization of a polymer, or gold nanoparticules which can be stabilized by thiolate ligands or by dendrimers in an intra- or inter-dendritic way. These nano-objects were designed with the aim of encapsulating, stabilizing or improving various biological molecules such as vitamins (vitamin C, B3 and B6), neurotransmitters (acetylcholine and dopamine) or anti-cancerous agents (daunorubicine)

A 3D-printable hydrogel formulation for the local delivery of therapeutic nanoparticles to cervical cancer

Cervical cancer is the fourth most common malignancy among women. Compared to other types of cancer, therapeutic agents can be administrated locally at the mucosal vaginal membrane. Thermosensitive gels have been developed over the years for contraception, or for the treatment of bacterial, fungal, and sexually transmitted infections. These formulations often carry therapeutic nanoparticles and are now being considered in the arsenal of tools for oncology. They can also be 3D-printed for a better geometrical adjustment to the anatomy of the patient, thus enhancing the local delivery treatment. In this study, a localized delivery system composed of a Pluronic F127-alginate hydrogel with efficient nanoparticle (NP) release properties was prepared for intravaginal application procedures. The kinetics of hydrogel degradation and its NP releasing properties were demonstrated with ultra-small gold nanoparticles (~80% of encapsulated AuNPs released in 48 h). The mucoadhesive properties of the hydrogel formulation were assayed by the periodic acid/Schiff’s reagent staining, which revealed that 19% of mucins were adsorbed on the gel’s surface. The hydrogel formulation was tested for cytocompatibility in three cell lines (HeLa, CRL 2616, and BT-474; no sign of cytotoxicity revealed). The release of AuNPs from the hydrogel and their accumulation in vaginal membranes were quantitatively measured in vitro/ex vivo with positron emission tomography (PET), a highly sensitive imaging modality allowing real-time imaging of nanoparticle diffusion (lag time to start of permeation 3.3 h, 47% of AuNPs accumulated in the mucosa after 42 h). Finally, the potential of the AuNPs-containing Pluronic F127-alginate hydrogel for 3D-printing was demonstrated, and the geometrical precision of the 3D-printed systems was measured by magnetic resonance imaging (MRI, <0.5 mm precision; deviation from the design values <2.5%). In summary, this study demonstrates the potential of Pluronic F127-alginate formulations for the topical administration of NP-releasing gels applied to vaginal wall therapy. This technology could open new possibilities for photothermal and radiosensitizing oncology applications

Miniaturized FDDA and CMOS Based Potentiostat for Bio-Applications

A novel fully differential difference CMOS potentiostat suitable for neurotransmitter sensing is presented. The described architecture relies on a fully differential difference amplifier (FDDA) circuit to detect a wide range of reduction-oxidation currents, while exhibiting low-power consumption and low-noise operation. This is made possible thanks to the fully differential feature of the FDDA, which allows to increase the source voltage swing without the need for additional dedicated circuitry. The FDDA also reduces the number of amplifiers and passive elements in the potentiostat design, which lowers the overall power consumption and noise. The proposed potentiostat was fabricated in 0.18 µm CMOS, with 1.8 V supply voltage. The device achieved 5 µA sensitivity and 0.99 linearity. The input-referred noise was 6.9 µV rms and the flicker noise was negligible. The total power consumption was under 55 µW. The complete system was assembled on a 20 mm × 20 mm platform that includes the potentiostat chip, the electrode terminals and an instrumentation amplifier for redox current buffering, once converted to a voltage by a series resistor. the chip dimensions were 1 mm × 0.5 mm and the other PCB components were off-chip resistors, capacitors and amplifiers for data acquisition. The system was successfully tested with ferricyanide, a stable electroactive compound, and validated with dopamine, a popular neurotransmitter

The hydrophobic region of the <i>Leishmania peroxin</i> 14:requirements for association with a glycosome mimetic membrane

Protein import into the Leishmania glycosome requires docking of the cargo-loaded peroxin 5 (PEX5) receptor to the peroxin 14 (PEX14) bound to the glycosome surface. To examine the LdPEX14-membrane interaction, we purified L. donovani promastigote glycosomes and determined the phospholipid and fatty acid composition. These membranes contained predominately phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol (PG) modified primarily with C18 and C22 unsaturated fatty acid. Using large unilamellar vesicles (LUVs) with a lipid composition mimicking the glycosomal membrane in combination with sucrose density centrifugation and fluorescence-activated cell sorting technique, we established that the LdPEX14 membrane-binding activity was dependent on a predicted transmembrane helix found within residues 149-179. Monolayer experiments showed that the incorporation of PG and phospholipids with unsaturated fatty acids, which increase membrane fluidity and favor a liquid expanded phase, facilitated the penetration of LdPEX14 into biological membranes. Moreover, we demonstrated that the binding of LdPEX5 receptor or LdPEX5-PTS1 receptor-cargo complex was contingent on the presence of LdPEX14 at the surface of LUVs.</p

The Human Tissue-Engineered Cornea (hTEC): Recent Progress

Each day, about 2000 U.S. workers have a job-related eye injury requiring medical treatment. Corneal diseases are the fifth cause of blindness worldwide. Most of these diseases can be cured using one form or another of corneal transplantation, which is the most successful transplantation in humans. In 2012, it was estimated that 12.7 million people were waiting for a corneal transplantation worldwide. Unfortunately, only 1 in 70 patients received a corneal graft that same year. In order to provide alternatives to the shortage of graftable corneas, considerable progress has been achieved in the development of living corneal substitutes produced by tissue engineering and designed to mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Most of these substitutes use synthetic biomaterials combined with immortalized cells, which makes them dissimilar from the native cornea. However, studies have emerged that describe the production of tridimensional (3D) tissue-engineered corneas using untransformed human corneal epithelial cells grown on a totally natural stroma synthesized by living corneal fibroblasts, that also show appropriate histology and expression of both extracellular matrix (ECM) components and integrins. This review highlights contributions from laboratories working on the production of human tissue-engineered corneas (hTECs) as future substitutes for grafting purposes. It overviews alternative models to the grafting of cadaveric corneas where cell organization is provided by the substrate, and then focuses on their 3D counterparts that are closer to the native human corneal architecture because of their tissue development and cell arrangement properties. These completely biological hTECs are therefore very promising as models that may help understand many aspects of the molecular and cellular mechanistic response of the cornea toward different types of diseases or wounds, as well as assist in the development of novel drugs that might be promising for therapeutic purposes

The Human Tissue-Engineered Cornea (hTEC): Recent Progress

Each day, about 2000 U.S. workers have a job-related eye injury requiring medical treatment. Corneal diseases are the fifth cause of blindness worldwide. Most of these diseases can be cured using one form or another of corneal transplantation, which is the most successful transplantation in humans. In 2012, it was estimated that 12.7 million people were waiting for a corneal transplantation worldwide. Unfortunately, only 1 in 70 patients received a corneal graft that same year. In order to provide alternatives to the shortage of graftable corneas, considerable progress has been achieved in the development of living corneal substitutes produced by tissue engineering and designed to mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Most of these substitutes use synthetic biomaterials combined with immortalized cells, which makes them dissimilar from the native cornea. However, studies have emerged that describe the production of tridimensional (3D) tissue-engineered corneas using untransformed human corneal epithelial cells grown on a totally natural stroma synthesized by living corneal fibroblasts, that also show appropriate histology and expression of both extracellular matrix (ECM) components and integrins. This review highlights contributions from laboratories working on the production of human tissue-engineered corneas (hTECs) as future substitutes for grafting purposes. It overviews alternative models to the grafting of cadaveric corneas where cell organization is provided by the substrate, and then focuses on their 3D counterparts that are closer to the native human corneal architecture because of their tissue development and cell arrangement properties. These completely biological hTECs are therefore very promising as models that may help understand many aspects of the molecular and cellular mechanistic response of the cornea toward different types of diseases or wounds, as well as assist in the development of novel drugs that might be promising for therapeutic purposes