Tuning viscoelasticity and stiffness in bioprinted hydrogels for enhanced 3D cell culture: A multi-scale mechanical analysis.

Bioprinted hydrogels are extensively studied to provide an artificial matrix for 3D cell culture. The success of bioprinting hydrogels relies on fine-tuning their rheology and composition to achieve shear-thinning behavior. However, a challenge arises from the limited viscoelastic and stiffness range accessible from a single hydrogel formulation.

Crystal and molecular structure of V-amylose complexed with ibuprofen.

Rectangular V-amylose single crystals were prepared by adding racemic ibuprofen to hot dilute aqueous solutions of native and enzymatically-synthesized amylose. The lamellar thickness increased with increasing degree of polymerization of amylose and reached a plateau at about 7 nm, consistent with a chain-folding mechanism. The CP/MAS NMR spectrum as well as base-plane electron and powder X-ray diffraction patterns recorded from hydrated specimens were similar to those of V-amylose complexed with propan-2-ol.

Interfacial rheological properties of self-assembling biopolymer microcapsules.

Tuning the mechanical properties of microcapsules through a cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step.

Structural Variations in Hybrid All-Nanoparticle Gibbsite Nanoplatelet/Cellulose Nanocrystal Multilayered Films.

Cellulose nanocrystals (CNCs) are promising biosourced building blocks for the production of high performance materials. In the last ten years, CNCs have been used in conjunction with polymers for the design of multilayered thin films via the layer-by-layer assembly technique. Herein, polymer chains have been replaced with positively charged inorganic gibbsite nanoplatelets (GN) to form hybrid "nanoparticle-only" composite films.

[Proposals to adapt the protection of children to the realities of today].

The report titled "40 propositions pour adapter la protection de l'enfance et l'adoption aux réalités d'aujourd'hui" ("Forty proposals to adapt protection of children to the realities of today") was presented in February 2014 by the "Protection de l'enfance et adoption" working group to the Minister for Family Affairs within the framework of the preparation of the French family law. The medical field is an important link in the chain of child protection. Of the 40 proposals, particular attention was paid to the identification of children at risk and to improving the protection of newborns (shaken baby syndrome, unexpected infant death) and to adoption issues.

Preparation and enzymatic hydrolysis of nanoparticles made from single xyloglucan polysaccharide chain.

In this work, polysaccharide nanoparticles based on tamarind seeds xyloglucan are prepared, analyzed in term of characteristic sizes and morphology, and degraded by the action of a glycoside-hydrolase. Obtained in an aqueous NaNO2 solution (0.1M), these unaggregated nanoparticles have a characteristic diameter of ca.

Probing multivalent host-guest interactions between modified polymer layers by direct force measurement.

The adhesion behavior between modified polysaccharide layers capable of forming host-guest complexes has been determined by direct force measurements with the atomic force microscope (AFM). Polysaccharides bearing either host or guest moieties were obtained by derivatization of chitosan with pendant β-cyclodextrin (CD) and adamantane (AD) moieties, respectively. These modified polysaccharides were covalently immobilized either to flat surfaces or to AFM-probes.

Designing hyaluronic acid-based layer-by-layer capsules as a carrier for intracellular drug delivery.

Polyelectrolyte microcapsules were prepared by the layer-by-layer assembly of hyaluronic acid (HA) and a polycationic polymer, poly(allylamine) (PAH) or poly(lysine) (PLL). The influence of the polycationic partner on the morphology, stability, permeability properties, and enzymatic degradation of microcapsules was thoroughly analyzed. It was found that these properties could be tuned by shell cross-linking.

Structural basis of the affinity for oligomannosides and analogs displayed by BC2L-A, a Burkholderia cenocepacia soluble lectin.

The opportunistic pathogen Burkholderia cenocepacia contains three soluble carbohydrate-binding proteins, related to the fucose-binding lectin PA-IIL from Pseudomonas aeruginosa. All contain a PA-IIL-like domain and two of them have an additional N-terminal domain that displays no sequence similarities with known proteins. Printed arrays screening performed on the shortest one, B.

Non-electrostatic building of biomimetic cellulose-xyloglucan multilayers.

Layer-by-layer assembly was used to build thin films, consisting of multiple layers alternating cellulose nanocrystals and xyloglucan, benefiting from the strong non-electrostatic cellulose-xyloglucan interaction. Data from atomic force microscopy and neutron reflectivity showed that these well-defined films exhibited a thickness increasing linearly with the number of layers, without increase in surface roughness. These "green" nanocomposite films, reminiscent of plant cell wall, are composed of a regular stack of single layers of cellulose nanocrystals separated by very thin xyloglucan spacers.

Structural details of cellulose nanocrystals/polyelectrolytes multilayers probed by neutron reflectivity and AFM.

Neutron reflectivity measurements and AFM observations were used as complementary techniques to investigate multilayered films consisting of alternating sheets of rigid cellulose nanocrystals and flexible poly(allylamine hydrochloride) (PAH) prepared by the layer-by-layer assembly technique. Both techniques showed that smooth films with a high load of cellulose could be obtained. After deposition, the cellulose component occurred as a double layer with different densities: 50% and 25% for the lower and upper layer, respectively.

The shape and size distribution of crystalline nanoparticles prepared by acid hydrolysis of native cellulose.

The shape and size distribution of crystalline nanoparticles resulting from the sulfuric acid hydrolysis of cellulose from cotton, Avicel, and tunicate were investigated using transmission electron microscopy (TEM) and atomic force microscopy (AFM) as well as small- and wide-angle X-ray scattering (SAXS and WAXS). Images of negatively stained and cryo-TEM specimens showed that the majority of cellulose particles were flat objects constituted by elementary crystallites whose lateral adhesion was resistant against hydrolysis and sonication treatments. Moreover, tunicin whiskers were described as twisted ribbons with an estimated pitch of 2.

[Macular hole surgery with and without infracyanine-green-guided removal of the internal limiting membrane].

Purpose: To investigate the possibility of an adverse effect of infracyanine-guided internal limiting membrane (ILM) removal on functional results of macular hole surgery.

Patients And Methods: A retrospective study of two consecutive groups of patients operated for macular hole between January 1998 and December 2001. In group 1 (21 patients), no attempt was made to remove the internal limiting membrane.

Isolated conjunctival ulcerations as the first sign of Behçet's disease.

Purpose: To report an unusual incident of isolated conjunctival ulcerations which preceded all other signs of Behçet's disease.

Methods: Description of a 34-year-old woman of West Indian origin with an unremarkable medical history presenting with bilateral bulbar conjunctival ulcerations.

Results: The authors noted the presence of a diffuse bilateral conjunctival hyperemia which was more pronounced at the temporal bulbar conjunctiva of the right eye and the nasal conjunctiva of the left eye, each having one ulceration.

Isolated conjunctival ulcerations as the first sign of Behets disease.

Purpose: To report an unusual incident of isolated conjunctival ulcerations which preceded all other signs of Behets disease.

Methods: Description of a 34-year-old woman of West Indian origin with an unremarkable medical history presenting with bilateral bulbar conjunctival ulcerations.

Results: The authors noted the presence of a diffuse bilateral conjunctival hyperemia which was more pronounced at the temporal bulbar conjunctiva of the right eye and the nasal conjunctiva of the left eye, each having one ulceration.

Refractory multicentric reticulohistiocytosis treated by infliximab: two cases.

We report the effect of infliximab, a monoclonal anti-TNFalpha antibody, in two patients with refractory cutaneous and articular multicentric reticulohistiocytosis (MRH). One 37-year-old woman and one 53-year-old woman with polyarthritis, facial rash and nodular lesions on the hands related to MRH were refractory to multiple agents: cariolysine, corticosteroids, hydroxychloroquine and cytotoxic agents. Infliximab at 3 mg/kg which was then increased to 5 mg/kg in combination with methotrexate or azathioprine was effective on cutaneous manifestations of the disease but not on polyarthritis.

[Advantages of confocal microscopy in the analysis of epiretinal membranes and internal limiting membranes after macular surgery].

Purpose: To study specimens obtained from epiretinal membrane (ERM) and macular hole surgery with confocal microscopy and to evaluate its advantages in understanding their pathophysiology.

Material And Methods: This retrospective study included 50 patients undergoing surgery for epiretinal membrane (40 patients) or idiopathic macular hole (10 patients). Infracyanine green was used in 45 cases.

Effect of shear stress on adhering polyelectrolyte capsules.

A parallel plate flow chamber was implemented to study the deformation and adhesion of individual spherical hollow polyelectrolyte multilayered shells adhering to a coated surface. The device provides a well-defined laminar flow allowing the determination of the shear stress to which the capsules are being exposed up to 15 N/m(2). The results of the investigations indicate a strong dependence of the adhesion and mechanical resistance on the capsule size and wall thickness.

Tuning of microcapsule adhesion by varying the capsule-wall thickness.

The adhesion area and topology of spherical hollow polyelectrolyte shells adhering to flat glass or polyelectrolyte-covered glass surfaces are studied. Strong adhesion is found for anionic poly(sodium 4-styrenesulfonate)-terminated shells on cationic poly(ethylene imine)-covered glass, while no adhesion of those shells on uncoated glass is found. The adhering shells are deformed and obtain a truncated sphere topology with a circular adhesion disk.

Elastic properties of polyelectrolyte capsules studied by atomic-force microscopy and RICM.

Mechanical properties of polyelectrolyte multilayer capsules were studied using a new method combining atomic-force microscopy and reflection interference contrast microscopy. By measuring the force vs. deformation for poly(styrene sulfonate)/poly(allylamine) capsules the existence of different deformation regimes depending on the applied deformation was shown.

[Peripheral facial paralysis in a patient infected with HTLV-1 virus. 2 case reports].

Introduction: Facial nerve palsy is a frequent situation of varying etiology and the former concept of frozen facial nerves is progressively being abandoned. The HTLV-1 virus, endemic to some tropical areas, is one of the most recent causes discovered.

Observations: We present two HTLV-1 seropositive patients of Caribbean origin who developed facial palsy and several complications related to this retrovirus.

[Systemic lupus erythematosus in Martinique: an epidemiologic study].

Purpose: To review epidemiological and clinical aspects of systemic lupus erythematosus (SLE) in Martinique, French West Indies.

Methods: Cases of SLE were identified by attending physicians. Patients who presented with at least four of the criteria defined by the American College of Rheumatology were included.

[Acute disseminated encephalomyelitis preceding cutaneous lupus].

Study Design: A case of acute disseminated encephalomyelitis (ADEM) preceding the features of cutaneous lupus is reported.

Objectives: To suggest that ADEM and cutaneous lupus are pathophysiologically related.

Summary Of The Background Data: Neurological complications of systemic lupus erythematosus are common.