Subcutaneous Application of a Gelatin/Hyaluronic Acid Hydrogel Induces the Production of Skin Extracellular Matrix.

The development of injectable hydrogels with natural biopolymers such as gelatin (Ge) and hyaluronic acid (Ha) is widely performed due to their biocompatibility and biodegradability. The combination of both polymers crosslinked with N-Ethyl-N'-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) can be used as an innovative dermal filler that stimulates fibroblast activity and increases skin elasticity and tightness. Thus, crosslinked Ge/Ha hydrogels with different concentrations of EDC were administered subcutaneously to test their efficacy in young and old rats. At higher EDC concentrations, the viscosity decreases while the particle size of the hydrogels increases. At all concentrations of EDC, amino and carboxyl groups are present. The histological analysis shows an acute inflammatory response, which disappears seven days after application. At one and three months post-treatment, no remains of the hydrogels are found, and the number of fibroblasts increases in all groups in comparison with the control. In addition, the elastic modulus of the skin increases after three months of treatment. Because EDC-crosslinked Ge/Ha hydrogels are biocompatible and induce increased skin tension, fibroblast proliferation, and de novo extracellular matrix production, we propose their use as a treatment to attenuate wrinkles and expression lines.

Photomechanical Polymer Nanocomposites for Drug Delivery Devices.

We demonstrate a novel structure based on smart carbon nanocomposites intended for fabricating laser-triggered drug delivery devices (DDDs). The performance of the devices relies on nanocomposites' photothermal effects that are based on polydimethylsiloxane (PDMS) with carbon nanoparticles (CNPs). Upon evaluating the main features of the nanocomposites through physicochemical and photomechanical characterizations, we identified the main photomechanical features to be considered for selecting a nanocomposite for the DDDs. The capabilities of the PDMS/CNPs prototypes for drug delivery were tested using rhodamine-B (Rh-B) as a marker solution, allowing for visualizing and quantifying the release of the marker contained within the device. Our results showed that the DDDs readily expel the Rh-B from the reservoir upon laser irradiation and the amount of released Rh-B depends on the exposure time. Additionally, we identified two main Rh-B release mechanisms, the first one is based on the device elastic deformation and the second one is based on bubble generation and its expansion into the device. Both mechanisms were further elucidated through numerical simulations and compared with the experimental results. These promising results demonstrate that an inexpensive nanocomposite such as PDMS/CNPs can serve as a foundation for novel DDDs with spatial and temporal release control through laser irradiation.

Long-Term Follow-Up After Fat Graft Myringoplasty: Do Size and Location Matter?

OBJECTIVE: To assess clinical and functional outcomes of a fat graft myringoplasty under local in an office setting. STUDY DESIGN: Prospective case series. SETTING: Tertiary care facility. PATIENTS: Patients with a tympanic membrane (TM) perforation presenting between December 2005 and June 2019. Inclusion criteria included perforation size >25% of the surface of the pars tensa of the TM, entire perforation margins visualized through a transcanal view, and lack of spontaneous closure at the 6-month follow-up. The exclusion criteria were the presence of cholesteatoma, wet appearance of the mucosa in the tympanic cavity, ear discharge in the 3 months before surgery, or signs of ossicular inconsistency. INTERVENTION: In-office fat graft myringoplasty technique under local anesthesia. MAIN OUTCOME MEASURES: Complete perforation closure rate and audiometric outcomes. RESULTS: A total of 121 patients underwent the procedure, of whom 21 had bilateral sequential procedures (total 142 ears). Average age was 51.1 ± 18.4 years (range, 3-78 years). The size of perforation was <25% of TM in 39 (27.5%) ears, 25% to 50% of TM in 49 (34.55%) ears, 50% to 75% of TM in 34 (23.91%) ears, and 75% to 100% of TM in 20 (14.10%) ears. Complete perforation closure was evident in 130 (91.55%) of the 142 ears. Preoperative mean air conduction threshold was 59.3 dB (17-95 dB) and significantly improved into 35.6 dB (10-85 dB; P < .0004) after surgery. Preoperative air-bone gap was 30.2 dB (5-70 dB) and also significantly improved into 10.2 dB (5-65 dB; P < .0001) after surgery. CONCLUSION: In office fat graft myringoplasty, in adult and pediatric patients with variable perforation sizes, is a well-tolerated procedure with very satisfactory clinical results.

First record of the gray-legged tinamou, Crypturellus duidae, and other poor-soil specialist birds from peatlands in the Putumayo River basin, Loreto, Peru

Crypturellus duidae (Tinamidae) is a poor-soil specialist with isolated populations in Amazonia, and is considered restricted to white-sand forest habitats. We report the first record of C. duidae in a peatland forest in northern Peru, in the Putumayo River basin. Our record extends the known distribution of C. duidae between two disjoint areas of occurrence in Peru and Colombia, and shows its presence in peatland forest, another forest type on nutrient-poor soils. Additionally, we report the presence of other poor-soil specialist bird species that were previously registered in peatlands. Together with the new record of C. duidae, these bird records provide evidence of the diversity of poor-soil specialists in peatland forests. (AU)

Influence of the PLGA/gelatin ratio on the physical, chemical and biological properties of electrospun scaffolds for wound dressings.

Chronic wounds are a global health problem, and their treatments are difficult and long lasting. The development of medical devices through tissue engineering has been conducted to heal this type of wound. In this study, it was demonstrated that the combination of natural and synthetic polymers, such as poly (D-L lactide-co-glycolide) (PLGA) and gelatin (Ge), were useful for constructing scaffolds for wound healing. The aim of this study was to evaluate the influence of different PLGA/gelatin ratios (9:1, 7:3 and 5:5 (v/v)) on the physical, chemical and biological properties of electrospun scaffolds for wound dressings. These PLGA/Ge scaffolds had randomly oriented fibers with smooth surfaces and exhibited distances between fibers of less than 10 µm. The 7:3 and 5:5 PLGA/Ge scaffolds showed higher swelling, hydrophilicity and degradation rates than pure PLGA and 9:1 (v/v) PLGA/Ge scaffolds. Young's moduli of the scaffolds were 72 ± 10, 48 ± 6, 58 ± 6 and 6 ± 1 MPa for the pure PLGA scaffold and the 9:1, 7:3 and 5:5 (v/v) PLGA/Ge scaffolds, respectively. Mesenchymal stem cells (MSCs) seeded on all the PLGA/Ge scaffolds were viable, and the cells were attached to the fibers at the different analyzed timepoints. The most significant proliferation rate was observed for cells on the 7:3 PLGA/Ge scaffolds. Biocompatibility analysis showed that all the scaffolds produced inflammation at the first week postimplantation; however, the 7:3 and 5:5 (v/v) PLGA/Ge scaffolds were degraded completely, and there was no inflammatory reaction observed at the fourth week after implantation. In contrast, the 9:1 PLGA/Ge scaffolds persisted in the tissue for more than four weeks; however, at the eighth week, no traces of the scaffolds were found. In conclusion, the scaffolds with the 7:3 PLGA/Ge ratio showed suitable physical, chemical and biological properties for applications in chronic wound treatments.

Random laser imaging of bovine pericardium under the uniaxial tensile test.

We demonstrate random laser (RL) emission from within bovine pericardium (BP) tissue. The interest in BP relies on its wide use as a valve replacement and as a biological patch. By imaging the emitting tissue, we show that RL emission is mostly generated inside the collagen fibers. Multimode RL operation is thus achieved within the volume of each fiber. Image analysis reveals that the intensity of the RL emission from individual fibers is dependent on the relative orientation to the stress axis. Our results suggest that RL intensity may be used as an indicator of stress concentration in individual fibers.

Use of three-dimensional digital image correlation to evaluate mechanical response of prosthetic systems.

BACKGROUND AND AIM: The need of comfortable and safe prosthetic systems is an important challenge for both prosthetists and engineers. The aim of this technical note is to demonstrate the use of three-dimensional digital image correlation to evaluate mechanical response of two prosthetic systems under real patient dynamic loads. TECHNIQUE: This note describes the use of three-dimensional digital image correlation method to obtain full-field strain and displacement measurements on the surface of two lower limb prostheses for Chopart amputation. It outlines key points of the measurement protocol and illustrates the analysis of critical regions using data obtained on specific points of interest. DISCUSSION: The results show that the use of three-dimensional digital image correlation can be a tool for the prosthetist to optimize the prosthesis considering features related to the material and design, in order to bear with real patient-specific load conditions. Clinical relevance Three-dimensional digital image correlation can support decision-making on new designs and materials for prosthetics based on quantitative data. Better understanding of mechanical response could also assist prescription for appropriate prosthetic systems.

Photothermal Effects and Applications of Polydimethylsiloxane Membranes with Carbon Nanoparticles.

The advent of nanotechnology has triggered novel developments and applications for polymer-based membranes with embedded or coated nanoparticles. As an example, interaction of laser radiation with metallic and carbon nanoparticles has shown to provide optically triggered responses in otherwise transparent media. Incorporation of these materials inside polymers has led to generation of plasmonic and photothermal effects through the enhanced optical absorption of these polymer composites. In this work, we focus on the photothermal effects produced in polydimethylsiloxane (PDMS) membranes with embedded carbon nanoparticles via light absorption. Relevant physical parameters of these composites, such as nanoparticle concentration, density, geometry and dimensions, are used to analyze the photothermal features of the membranes. In particular, we analyze the heat generation and conduction in the membranes, showing that different effects can be achieved and controlled depending on the physical and thermal properties of the composite material. Several novel applications of these light responsive membranes are also demonstrated, including low-power laser-assisted micro-patterning and optomechanical deformation. Furthermore, we show that these polymer-nanoparticle composites can also be used as coatings in photonic and microfluidic applications, thereby offering an attractive platform for developing light-activated photonic and optofluidic devices.

Mechanical assessment of bovine pericardium using Müeller matrix imaging, enhanced backscattering and digital image correlation analysis.

Mechanical characterization of tissue is an important but complex task. We demonstrate the simultaneous use of Mueller matrix imaging (MMI), enhanced backscattering (EBS) and digital image correlation (DIC) in a bovine pericardium (BP) tensile test. The interest in BP relies on its wide use as valve replacement and biological patch. We show that the mean free path (MFP), obtained through EBS measurements, can be used as an indicator of the anisotropy of the fiber ensemble. Our results further show a good correlation between retardance images and displacement vector fields, which are intrinsically related with the fiber interaction within the tissue.

Preliminary study of an in vitro development of new tissue applying mechanical stimulation with a bioreactor as an alternative for ligament reconstruction.

Complete rupture of the anterior cruciate ligament (ACL) is a common problem in orthopedics. At present, there are many techniques to reconstruct ligaments, which include the use of autografts, allografts, and, in some cases, artificial ligaments. The latter have not provided good results in the short, medium, and long term. The purpose of present study was to engineer functional biological tissue that could potentially be used to replace the knee ligaments by applying tissue engineering techniques and mechanical stimulation with a bioreactor, promoting cellular differentiation and matrix synthesis. In this preliminary study, the new tissue was characterized with mechanical tests and biological tests (viability and immunochemistry), comparing their behavior with that of the native tissue. Mechanical and biological tests proved that mechanical stimulation administered with a bioreactor maintains the ligament fibroblast phenotype and promotes synthesis of the extracellular matrix.

Appraisal of a Leishmania major strain stably expressing mCherry fluorescent protein for both in vitro and in vivo studies of potential drugs and vaccine against cutaneous leishmaniasis.

BACKGROUND: Leishmania major cutaneous leishmaniasis is an infectious zoonotic disease. It is produced by a digenetic parasite, which resides in the phagolysosomal compartment of different mammalian macrophage populations. There is an urgent need to develop new therapies (drugs) against this neglected disease that hits developing countries. The main goal of this work is to establish an easier and cheaper tool of choice for real-time monitoring of the establishment and progression of this pathology either in BALB/c mice or in vitro assays. To validate this new technique we vaccinated mice with an attenuated Δhsp70-II strain of Leishmania to assess protection against this disease. METHODOLOGY: We engineered a transgenic L. major strain expressing the mCherry red-fluorescent protein for real-time monitoring of the parasitic load. This is achieved via measurement of fluorescence emission, allowing a weekly record of the footpads over eight weeks after the inoculation of BALB/c mice. RESULTS: In vitro results show a linear correlation between the number of parasites and fluorescence emission over a range of four logs. The minimum number of parasites (amastigote isolated from lesion) detected by their fluorescent phenotype was 10,000. The effect of antileishmanial drugs against mCherry+L. major infecting peritoneal macrophages were evaluated by direct assay of fluorescence emission, with IC(50) values of 0.12, 0.56 and 9.20 µM for amphotericin B, miltefosine and paromomycin, respectively. An experimental vaccination trial based on the protection conferred by an attenuated Δhsp70-II mutant of Leishmania was used to validate the suitability of this technique in vivo. CONCLUSIONS: A Leishmania major strain expressing mCherry red-fluorescent protein enables the monitoring of parasitic load via measurement of fluorescence emission. This approach allows a simpler, faster, non-invasive and cost-effective technique to assess the clinical progression of the infection after drug or vaccine therapy.

Modificaciones estructurales inducidas por la Diábetes en cristalinos cultivados in vitro / Structurals modifications induced by diabetes in vitro cultivate crystalline

La diábetes es una enfermedad sistémica en la cual existe una alteración en el metabolismo de los carbohidratos. A nivel oftalmológico una de las estructúras que se afectan es el cristalino. En los diabéticos, el humor acuoso presenta niveles de glucosa aumentados, y en el cristalino niveles superiores a 200 mgs/ml, saturan la enzima hexokinasa, convirtiéndose la glucosa en sorbitol, que se acumula entre las fibras cristalinianas y el epitelio, apareciendo la catarata, que en su evolución se hace intumescente. Aún no se conoce con exactitud el mecanismo por el cual se produce la catarata subcapsular posterior. También en el humor acuosos existen factores de crecimiento, dentro de los cuales está el IGFI que favorece crecimiento y diferenciación celular, pudiendo éste ser un factor que favorezca la aparición de catarata subcapsular posterior. El propósito de este trabajo es determinar las modificaciones celulares que ocurren en cristalinos cultivados en medio 199, glucosa (300 mgr/ml) e IGFI, para evaluar el papel que pudiera desempeñar el IGFC en la aparición de catarata diabética y sus implicaciones en el desarrollo de la catarata subcapsular posterior. Se utilizaron conejos albinos New Zealand, los cuales se anestesiaron y enuclearon para la posterior extracción del cristalino. Un grupo fue tratado con IGFI a concentraciones que oscilaron entre 0.5 -2-0 ng/ml, y cultivados en medio 199 + glucosa. Los cristalinos control se cultivaron en medio 199 + glucosa y medio 199 + suero. Los resultados indican que el IGFI indujo mitosis, hiperplasia y migración de las células epiteliales hacia la cápsula posterior, por lo que consideramos que éste pudiera ser un factor que puede favorecer por una vía no metabólica la aparición de catarata subcapsular posterior