Radiocapitellar and Ulnotrochlear Pressures Increase in a Radial Head Fracture Model: A Cadaveric Biomechanical Analysis.

BACKGROUND: Changes in intra-articular pressure have not been previously described in relation to the management of radial head fractures. We hypothesized that pressure within the radiocapitellar and ulnotrochlear joints would increase with progressive radial head resection, mimicking a displaced radial head fracture, in a cadaveric model. METHODS: Ten cadaveric specimens were tested. Intra-articular pressure sensors were used to measure pressure within the radiocapitellar and ulnotrochlear joints with the forearm in full supination. The elbow was loaded to 100 N in extension, 45° of flexion, and 90° of flexion under the following conditions: (1) intact radial head, (2) 20% radial head resection, (3) 40% radial head resection, and (4) 100% radial head resection. RESULTS: The distribution of pressure between the radiocapitellar and ulnotrochlear joints did not change with sequential, partial resection of the radial head (radiocapitellar joint, between 48.92% and 53.79%; ulnotrochlear joint, between 46.21% and 51.08%). After 20% resection, radiocapitellar peak contact pressure (PCP) increased by 22% (from 1,410 to 1,721.5 kPa) and ulnotrochlear PCP increased by 36% (from 1,319 to 1,797.5 kPa). After 40% resection, radiocapitellar PCP increased by 123% (from 1,410 to 3,145 kPa; p = 0.0003) and ulnotrochlear PCP increased by 105% (from 1,319 to 2,702 kPa; p = 0.007). Ulnotrochlear PCP increased by a total of 159% after complete radial head resection (from 1,319 to 3,415.5 kPa; p = 0.003). CONCLUSIONS: Pressures in the radiocapitellar and ulnotrochlear joints were equally distributed with an intact radial head and after partial resection. Radiocapitellar and ulnotrochlear pressures increased with increasing radial head resection, significantly exceeding 100% of normal after radial head resection of 40% of the anterolateral diameter. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

A Systematic Analysis of Additive Manufacturing Techniques in the Bioengineering of In Vitro Cardiovascular Models.

Additive Manufacturing is noted for ease of product customization and short production run cost-effectiveness. As our global population approaches 8 billion, additive manufacturing has a future in maintaining and improving average human life expectancy for the same reasons that it has advantaged general manufacturing. In recent years, additive manufacturing has been applied to tissue engineering, regenerative medicine, and drug delivery. Additive Manufacturing combined with tissue engineering and biocompatibility studies offers future opportunities for various complex cardiovascular implants and surgeries. This paper is a comprehensive overview of current technological advancements in additive manufacturing with potential for cardiovascular application. The current limitations and prospects of the technology for cardiovascular applications are explored and evaluated.

Millifluidic-assisted ionic gelation technique for encapsulation of probiotics in double-layered polysaccharide structure.

A unique double-layered vehicle was fabricated for the first time based on a millifluidic/direct gelation to encapsulate probiotics. Free probiotic bacteria are usually very sensitive to severe gastrointestinal conditions and maintaining their survival when passing through the digestive tract is essential. The effects of alginate concentration (20-30 g/L), flow rates of alginate (0.8-1.2 mL/min), and W/O emulsion (0.5-0.7 mL/min) on encapsulation efficiency (EE), size, and sphericity of core-shell millicapsules were optimized for encapsulation of Bifidobacterium animalis subsp. lactis and Lactobacillus plantarum. The optimized calcium-alginate millicapsule was spherical (0.97 ± 0.01 SF), with an average diameter of 4.49 ± 0.19 mm, and encapsulation efficiency of 98.17 ± 0.5 %. Two strains were encapsulated separately in W/O emulsion as a core of the millicapsule. After coating with chitosan, the encapsulation yield of the bacteria, survival rates under simulated gastrointestinal (GI) conditions, and viability during storage were determined. Survival efficiency of B. animalis subsp. lactis and L. plantarum after millifluidic encapsulation were found to be 92.33 and 90.81 %, respectively. Cell viability of encapsulated probiotics after passing through the GI system was improved (7.5 log CFU mL-1 for both strains). Although the viability of the encapsulated probiotics stored at -18 °C for five months significantly decreased (p<0.05), the number of live cells was approximately in accordance with the standard definition of long-term probiotic survival (6 log CFU/g). This work provides a pathway for the construction of an innovative delivery system with high efficiency and protective effects for probiotics.

Use of Stacked Layers of Electrospun L-Lactide/Glycolide Co-Polymer Fibers for Rapid Construction of Skin Sheets.

This paper describes a novel method for the rapid construction of skin, using multiple layers of aligned electrospun fibers as starting scaffolds. Scaffolds were spun from biodegradable L-lactide/glycolide (molar ratio 10:90) with predominantly parallel arrays of fibers attached peripherally to thin 304 stainless steel layer frames. Each layer frame was held between two thicker support frames. Human skin cells were seeded onto multiple (three-nine) scaffolds. Dermal fibroblasts were seeded on both sides of each scaffold except for one on which keratinocytes were seeded on one side only. Following 48 h of culture, the scaffolds and layer frames were unmounted from their support frames, stacked, with keratinocytes uppermost, and securely held in place by upper and lower support frames to instantly form a multilayered "dermis" and a nascent epidermis. The stack was cultured for a further 5 days during which time the cells proliferated and then adhered to form, in association with the spun fibers, a mechanically coherent tissue. Fibroblasts preferentially elongated in the dominant fiber direction and a two-dimensional weave of alternating fiber and cell alignments could be constructed by selected placement of the layer frames during stacking. Histology of the 7-day tissue stacks showed the organized layers of fibroblasts and keratinocytes immuno-positive for keratin. Electron microscopy showed attachment of fibroblasts to the lactide/glycolide fibers and small-diameter collagen fibers in the extracellular space. This novel approach could be used to engineer a range of tissues for grafting where rapid construction of tissues with aligned or woven layers would be beneficial.

Electrospray-assisted encapsulation of caffeine in alginate microhydrogels.

One of the major challenges with microencapsulation and delivery of low molecular weight bioactive compounds is their diffusional loss during storage and process conditions as well as under gastric conditions. In an attempt to slow down the release rate of core material, electrospray fabricated calcium alginate microhydrogels were coated with low molecular weight and high molecular weight chitosans. Caffeine as a hydrophilic model compound was used due to its several advantages on human behavior especially increasing consciousness. Mathematical modeling of the caffeine release by fitting the data with Korsmeyer-Peppas model showed that Fick's diffusion law could be the prevalent mechanism of the release. Electrostatic interaction between alginate and chitosan (particularly in the presence of 1% low molecular weight chitosan) provided an effective barrier against caffeine release and significantly reduced swelling of particles compared to control samples. The results of this study demonstrated that calcium alginate microhydrogels coated by chitosan could be used for encapsulation of low molecular compounds. However, more complementary research must be done in this field. In addition, electrospray, by producing monodisperse particles, would be as an alternative method for fabrication of microparticles based on natural polymers.

Principles of electrospraying: A new approach in protection of bioactive compounds in foods.

Electrospraying is a potential answer to the demands of nanoparticle fabrication such as scalability, reproducibility, and effective encapsulation in food nanotechnology. Electrospraying (and the related process of electrospinning) both show promise as a novel delivery vehicle for supplementary food compounds since the process can be carried out from an aqueous solution, at room temperature and without coagulation chemistry to produce matrices or particulates in the micro- and nano-range. The presentation of core materials at the nanoscale improves target ability to specific areas of the digestive tract and gives improved control of release rate. Adoption of these electrohydrodynamic atomization technologies will allow the industry to develop a wide range of novel high added value functional foods. To optimize production conditions and maximize throughput, a clear understanding of the mechanism of electrospraying is essential. This article presents a comprehensive review of the principles of electrospraying to produce nanoparticles suitable for food technology application, particularly for use in encapsulation and as nanocarriers.

Controlling the morphology and material characteristics of electrospray generated calcium alginate microhydrogels.

Electrospraying nano- and micro-particle fabrication is a one-step, non-invasive process, which has application in encapsulating of thermosensitive functional, bioactive materials and cells and making microhydrogels. This study investigates the effect of various electrospraying process parameters on the characteristics of calcium alginate microhydrogel particles. The alginate solution concentration, CaCl2 coagulation bath concentration, voltage, nozzle diameter, distance between nozzle and collecting bath (D), alginate delivery pressure (∼H) were examined. The best droplet formation rate, in non-disperse dripping mode, was obtained at 8 kV using a 500 µm inner diameter nozzle tip, D = 8 cm, H = 20 cm. Morphology, swelling behaviour and texture analysis of the particles which were followed by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) confirmed that 1.5-2% (w/v) CaCl2 was the desirable concentration for hydrogels formation. Particle size range between 267 and 1500 µm could be obtained by the drip feed mode compared with 2.3-6 µm by the pressure-assisted electrospray through a coaxial head.

Complementary characterization data in support of uniaxially aligned electrospun nanocomposites based on a model PVOH-epoxy system.

This paper presents complementary data corresponding to characterization tests done for our research article entitled "Uniaxially aligned electrospun fibers for advanced nanocomposites based on a model PVOH-epoxy system" (Karimi et al., 2016) [1]. Poly(vinyl alcohol) and epoxy resin were selected as a model system and the effect of electrospun fiber loading on polymer properties was examined in conjunction with two manufacturing methods. A novel electrospinning technology for production of uniaxially aligned nanofiber arrays was used. A conventional wet lay-up fabrication method is compared against a novel, hybrid electrospinning-electrospraying approach. The structure and thermomechanical properties of resulting composite materials were examined using scanning electron microscopy, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and tensile testing. For discussion of obtained results please refer to the research paper (Karimi et al., 2016) [1].

Characterization of the nitric oxide-reactive transcriptional activator NorR.

The prokaryotic transcriptional regulator NorR is unusual in that it utilizes a mononuclear ferrous iron center rather than a heme moiety as a means of sensing nitric oxide (NO). Binding of NO to the nonheme iron center in the amino-terminal GAF domain of NorR results in formation of a mononitrosyl iron complex and relieves intramolecular repression within NorR, allowing this regulatory protein, a member of the sigma(54)-dependent family of enhancer-binding proteins, to activate expression of genes required for NO detoxification. This chapter describes detailed protocols for measuring transcriptional activation by Escherichia coli NorR in vivo and in vitro. It also details spectroscopic methods for analysis of the interaction of NO with the nonheme iron center and determination of the NO-binding affinity constant.

Hand motion segmentation against skin colour background in breast awareness applications.

Skin colour modelling and classification play significant roles in face and hand detection, recognition and tracking. A hand is an essential tool used in breast self-examination, which needs to be detected and analysed during the process of breast palpation. However, the background of a woman's moving hand is her breast that has the same or similar colour as the hand. Additionally, colour images recorded by a web camera are strongly affected by the lighting or brightness conditions. Hence, it is a challenging task to segment and track the hand against the breast without utilising any artificial markers, such as coloured nail polish. In this paper, a two-dimensional Gaussian skin colour model is employed in a particular way to identify a breast but not a hand. First, an input image is transformed to YCbCr colour space, which is less sensitive to the lighting conditions and more tolerant of skin tone. The breast, thus detected by the Gaussian skin model, is used as the baseline or framework for the hand motion. Secondly, motion cues are used to segment the hand motion against the detected baseline. Desired segmentation results have been achieved and the robustness of this algorithm is demonstrated in this paper.

In utero gene transfer of human factor IX to fetal mice can induce postnatal tolerance of the exogenous clotting factor.

The fundamental hypotheses behind fetal gene therapy are that it may be possible (1) to achieve immune tolerance of transgene product and, perhaps, vector; (2) to target cells and tissues that are inaccessible in adult life; (3) to transduce a high percentage of rapidly proliferating cells, and in particular stem cells, with relatively low absolute virus doses leading to clonal transgene amplification by integrating vectors; and (4) to prevent early disease manifestation of genetic diseases. This study provides evidence vindicating the first hypothesis; namely, that intravascular prenatal administration of an adenoviral vector carrying the human factor IX (hFIX) transgene can induce immune tolerance of the transgenic protein. Following repeated hFIX protein injection into adult mice, after prenatal vector injection, we found persistence of blood hFIX and absence of hFIX antibodies in 5 of 9 mice. Furthermore, there was substantial hFIX expression after each of 2 reinjections of vector without detection of hFIX antibodies. In contrast, all adult mice that had not been treated prenatally showed a rapid loss of the injected hFIX and the development of high hFIX antibody levels, both clear manifestations of a strong immune reaction.