Bioprinting is an emerging field in regenerative medicine. Producing cell-laden, three-dimensional structures to mimic bodily tissues has an important role not only in tissue engineering, but also in ...drug delivery and cancer studies. Bioprinting can provide patient-specific spatial geometry, controlled microstructures and the positioning of different cell types for the fabrication of tissue engineering scaffolds. In this brief review, the different fabrication techniques: laser-based, extrusion-based and inkjet-based bioprinting, are defined, elaborated and compared. Advantages and challenges of each technique are addressed as well as the current research status of each technique towards various tissue types. Nozzle-based techniques, like inkjet and extrusion printing, and laser-based techniques, like stereolithography and laser-assisted bioprinting, are all capable of producing successful bioprinted scaffolds. These four techniques were found to have diverse effects on cell viability, resolution and print fidelity. Additionally, the choice of materials and their concentrations were also found to impact the printing characteristics. Each technique has demonstrated individual advantages and disadvantages with more recent research conduct involving multiple techniques to combine the advantages of each technique.
Purpose
Hamstring strain injury is a frequent and serious injury in competitive and recreational sports. While Nordic hamstring (NH) eccentric strength training is an effective hamstring ...injury-prevention method, the protective mechanism of this exercise is not understood. Strength training increases muscle strength, but also alters muscle architecture and stiffness; all three factors may be associated with reducing muscle injuries. The purpose of this study was to examine the effects of NH eccentric strength training on hamstring muscle architecture, stiffness, and strength.
Methods
Twenty healthy participants were randomly assigned to an eccentric training group or control group. Control participants performed static stretching, while experimental participants performed static stretching and NH training for 6 weeks. Pre- and post-intervention measurements included: hamstring muscle architecture and stiffness using ultrasound imaging and elastography, and maximal hamstring strength measured on a dynamometer.
Results
The experimental group, but not the control group, increased volume (131.5 vs. 145.2 cm
3
,
p
< 0.001) and physiological cross-sectional area (16.1 vs. 18.1 cm
2
,
p
= 0.032). There were no significant changes to muscle fascicle length, stiffness, or eccentric hamstring strength.
Conclusions
The NH intervention was an effective training method for muscle hypertrophy, but, contrary to common literature findings for other modes of eccentric training, did not increase fascicle length. The data suggest that the mechanism behind NH eccentric strength training mitigating hamstring injury risk could be increasing volume rather than increasing muscle length. Future research is, therefore, warranted to determine if muscle hypertrophy induced by NH training lowers future hamstring strain injury risk.
Applications of Metals for Bone Regeneration Glenske, Kristina; Donkiewicz, Phil; Köwitsch, Alexander ...
International journal of molecular sciences,
03/2018, Letnik:
19, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The regeneration of bone tissue is the main purpose of most therapies in dental medicine. For bone regeneration, calcium phosphate (CaP)-based substitute materials based on natural (allo- and ...xenografts) and synthetic origins (alloplastic materials) are applied for guiding the regeneration processes. The optimal bone substitute has to act as a substrate for bone ingrowth into a defect, as well as resorb in the time frame needed for complete regeneration up to the condition of
. In this context, the modes of action of CaP-based substitute materials have been frequently investigated, where it has been shown that such materials strongly influence regenerative processes such as osteoblast growth or differentiation and also osteoclastic resorption due to different physicochemical properties of the materials. However, the material characteristics needed for the required ratio between new bone tissue formation and material degradation has not been found, until now. The addition of different substances such as collagen or growth factors and also of different cell types has already been tested but did not allow for sufficient or prompt application. Moreover, metals or metal ions are used differently as a basis or as supplement for different materials in the field of bone regeneration. Moreover, it has already been shown that different metal ions are integral components of bone tissue, playing functional roles in the physiological cellular environment as well as in the course of bone healing. The present review focuses on frequently used metals as integral parts of materials designed for bone regeneration, with the aim to provide an overview of currently existing knowledge about the effects of metals in the field of bone regeneration.
Three-dimensional (3D) printing has become an important tool in the field of tissue engineering and its further development will lead to completely new clinical possibilities. The ability to create ...tissue scaffolds with controllable characteristics, such as internal architecture, porosity, and interconnectivity make it highly desirable in comparison to conventional techniques, which lack a defined structure and repeatability between scaffolds. Furthermore, 3D printing allows for the production of scaffolds with patient-specific dimensions using computer-aided design. The availability of commercially available 3D printed permanent implants is on the rise; however, there are yet to be any commercially available biodegradable/bioresorbable devices. This review will compare the main 3D printing techniques of: stereolithography; selective laser sintering; powder bed inkjet printing and extrusion printing; for the fabrication of biodegradable/bioresorbable bone tissue scaffolds; and, discuss their potential for dental applications, specifically augmentation of the alveolar ridge.
Bioprinting of tissue engineering scaffolds Rider, Patrick; Kačarević, Željka Perić; Alkildani, Said ...
Journal of Tissue Engineering,
2018 Jan-Dec, Letnik:
9
Book Review, Journal Article
Recenzirano
Odprti dostop
Bioprinting is the process of creating three-dimensional structures consisting of biomaterials, cells, and biomolecules. The current additive manufacturing techniques, inkjet-, extrusion-, and ...laser-based, create hydrogel structures for cellular encapsulation and support. The requirements for each technique, as well as the technical challenges of printing living cells, are discussed and compared. This review encompasses the current research of bioprinting for tissue engineering and its potential for creating tissue-mimicking structures.
A new, shorter version of cricket was introduced recently (Twenty20; T20). Since its inception, T20 cricket has rapidly become a popular and exciting format of cricket. However, there is little ...understanding of factors such as visual-motor control that influence expert performance.
The purpose of this project is to determine if a series of oculomotor measures can predict batting and bowling performance in professional cricket players.
This study used a cross-sectional design. Each participant took part in a suite of eye-tracking tests to measure oculomotor behavior compared to their performance data.
This study used a sample of 59 male T20 league professional cricket players (30 Bowlers and 29 Batsman).
One-way univariate analyses of variance examined the differences in oculomotor behavior between batsman and bowlers. A series of multiple regression analyses was conducted to evaluate how well the visual variables predict bowling and batting performance variables. Results demonstrate that several oculomotor eye tracking measures were good predictors of run performance and strike rate, including sports total score, sports on-field score, and sports functional score. Likewise, several of the same metrics predicted Runs and Wicket performance for bowlers. Overall, results provided further validation to a growing body of literature supporting the use of eye-tracking technology in performance evaluation.
Abstract Old adults execute single-joint voluntary movements with heightened antagonist muscle coactivation and altered timing between agonist and antagonist muscles. It is less clear if old adults ...adopt similar strategies during the most common form of activity of daily living, gait, and if age and gait velocity interact. We compared antagonist muscle activation amplitude and onset, offset, and activation duration of the vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius lateralis from surface EMG in 17 young (age 19–25) and 17 old adults (age 71–85) while walking at 1.2, 1.5, and 1.8 m/s. All participants were healthy and highly mobile. The activation level of the four muscles when each acted as the antagonist was, on the average, 83% higher in old vs young adults (for each muscle p < 0.05). In two of four muscles this activation increased with gait velocity in young but not in old adults. The inter-burst interval between TA and GL was two-fold (83 ms) longer in young vs old adults and at higher gait velocities it became 14% (24 ms) shorter in young but 51% (31 ms) longer in old adults (interaction, p = 0.015). It is concluded that there is an interaction between age and gait velocity in the amplitude and timing of antagonist muscle coactivation.
Nowadays, the most commonly used fixation systems are non-resorbable, but new resorbable magnesium alloy fixation screws have been introduced recently. Therefore, the aim of this study was to compare ...the magnesium fixation screw and the commonly used non-resorbable titanium screw in an animal model. Four 3-wall defect sites were covered with collagen membranes in the mandible of twenty beagle dogs (two sites on the left and two on the right). Each membrane was fixed with either four magnesium screws or four titanium screws. Post-operative follow-up revealed the expected observations such as transient inflammation and pain. Both groups showed a good healing response, with no differences between groups. Micro-CT analysis showed no significant difference between groups in terms of BV/TV or soft tissue volume. The void volume in the magnesium fixation screw group continued to decrease on average between the different timepoints, but not significantly. Furthermore, a gradual progression of the degradation process of the magnesium screws was observed in the same group. Magnesium screws and titanium screws showed equal performance in tissue regeneration according to GBR principles. An additional advantage of magnesium screws is their resorbable nature, which eliminates the need for a second surgical step to remove the screws.
Background and Objectives: A rigid, resorbable magnesium membrane was recently developed, combining the advantages of resorbable and non-resorbable membranes. Our aim was to describe the application ...of this membrane for guided bone regeneration (GBR). Materials and Methods: This case report described the treatment and 3D evaluation of two cases utilizing a resorbable magnesium barrier membrane. In Case #1, GBR was performed with a bilayer tunnel flap. The magnesium barrier was placed fixed subperiosteally through remote vertical incisions. In Case #2, GBR was performed using a split-thickness flap design. Volumetric and linear hard tissue alterations were assessed by 3D cone-beam computed tomography subtraction analysis, as well as with conventional intraoral radiography. Results: Case #1 showed a volumetric hard tissue gain of 0.12 cm3, whereas Case #2 presented a 0.36 cm3 hard tissue gain. No marginal peri-implant hard tissue loss could be detected at the two-year follow-up. Conclusions: The application of conventional resorbable collagen membranes would be difficult in either of the cases presented. However, the rigid structure of the magnesium membrane allowed for the limitations of conventional resorbable membranes to be overcome.
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