tissue constructs

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Monitored Steady State Excitation and Recovery (MSSER) radiation force imaging of engineered tissue constructs

Monitored Steady State Excitation and Recovery (MSSER) radiation force imaging of engineered tissue constructs

These current methods use a tensile test which results in the destruction of tissue construct being tested. The use of a tensile test is a loss of resources and time. 26 Current testing methods are discussed more in Chapter 3. MSSER would allow testing of mechanical properties to occur while the tissue constructs are still alive growing in culture media. MSSER also shows potential for being more accurate than the current method. Finite Element Analysis (FEA) is used to try and predict elastic modulus differences within the tissue constructs. This analysis assumes the tissue construct has linear elastic properties. 26 MSSER, designed for testing of viscoelastic materials, allows for a point by point analysis of the tissue constructs. For example, with this technology, it would be possible to detect focal areas of calcium deposition or hardening along these constructs. Although FEA is also capable of predicting local strains using a globally obtained elastic modulus value and geometric parameters of the construct, MSSER is capable of performing localized measurements along the tissue constructs. This also includes measurements at multiple depths within the tissue construct.
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Evaluating the Use of Engineered Nervous Tissue Constructs in the Repair of Peripheral Nerve Lesions and Amputations

Evaluating the Use of Engineered Nervous Tissue Constructs in the Repair of Peripheral Nerve Lesions and Amputations

While tremendous advancements have been made, there is no approach to date that directly integrates with the nervous system while leveraging the processing abilities of the brain and spinal cord. In contrast to all other strategies for neural interface development, we propose to exploit a novel method of engineering nervous tissue constructs as a means of interfacing a multi-electrode array (MEA) with regenerating peripheral nerves. The use of living neural tissue, which may be coupled to the MEA to form a stable interface prior to transplantation, provides an enticing target for host axon ingrowth and synaptic integration (Figure 5.4). By directly accessing the transected nerve, we eliminate the need for interpreting computationally complex neural signals in the CNS. Instead, upon integration, simple operant conditioning should allow the implantee to control the prosthesis with ease [Dhillon GS et al, 2004]. Thus, our approach builds upon current interface architecture capabilities and holds enormous promise to provide both motor control and sensory feedback for normal function.
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Effect of Adenosine Agonists on the Proliferation and Differentiation of Chick Embryo Fibroblasts in Three Dimensional Reconstituted Tissue Constructs

Effect of Adenosine Agonists on the Proliferation and Differentiation of Chick Embryo Fibroblasts in Three Dimensional Reconstituted Tissue Constructs

Adenosine agonists have been shown to have a pre- ventive effect on the differentiation of fibroblasts, they are believed to have an inhibitory action on the produc- tion of -SMA or stress fibers in fibroblasts. In our ex- periments western blot analysis did not reveal any per cell reduction of -SMA in CEF cells. Previous studies have shown that fibroblasts rapidly differentiate into myofibroblasts (as indicated by increased α-SMA ex- pression) when cultured on rigid substrates and/or in culture media containing serum and when plated at low density [‎27]. It has been found that untreated cardiac fibroblasts (CFs) spontaneously undergo this differen- tiation under normal culture conditions as shown by enhanced α-SMA expression in CF between passage 2 and passage 5. Thus adult rat CFs convert to myofibrob- lasts during early passage when plated on plastic tissue culture dishes in serum containing media emphasizing the importance of culture conditions in studies of the effects of exogenous agents on myofibroblast formation. For this reason, all differentiation studies should be conducted under serum- free conditions using low pas- sage‎ CFs‎ (passage‎ ≤‎ 2)‎ that‎ were‎ plated‎ at‎ relatively high‎ density‎ (‎ ≈‎ 200‎ cells/mm2). In our experiments differentiation still occurred in the presence of NECA, adenosine or control. Thus different treatment groups did not show a significant difference regarding fibrob- last differentiation. The present results may be influ-
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The interplay between tissue growth and scaffold degradation in engineered tissue constructs

The interplay between tissue growth and scaffold degradation in engineered tissue constructs

structs were investigated: (i) cell-cell and cell-scaffold interactions and, (ii) mechanotransduction mechanisms. The formulation was simplified via the long-wavelength limit (in which the biore- actor’s aspect ratio is assumed to be small) and by considering constant, spatially-homogeneous scaffold porosity. Numerical simulation of the model equations (validated by analytic solutions obtained in the limit of asymptotically-small cell volume fraction), revealed that inclusion of cell- cell and cell-scaffold interactions leads to significant differences in the extent to which the cell population colonises the scaffold, depending upon the relative importance of cell aggregation and repulsion. It was further shown that the composition of the resulting construct was strongly influ- enced by whether cell proliferation and ECM deposition were regulated by mechanical stimulation related to the cell population density, pressure or shear stress. Employing two-dimensional finite element simulations, Osborne et al. (2010) demonstrated that, when considering total tissue yield, the long-wavelength limit of O’Dea et al. (2010) provides an excellent approximation to the full two-dimensional model, even for relatively large values of bioreactor aspect ratio. However, this work further demonstrated that mechanotransduction-mediated tissue growth can lead to significant two-dimensional spatial variation of tissue density, a feature which is not captured by the long- wavelength limit. The authors concluded that, while spatial effects in two- or three-dimensions cannot be ignored in comprehensive models of tissue growth, its relative simplicity makes the long- wavelength model a natural framework with which to estimate parameters relevant to specific biore- actor systems, for subsequent use in more complex two- or three-dimensional models.
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A flow perfusion bioreactor with controlled mechanical stimulation: Application in cartilage tissue engineering and beyond

A flow perfusion bioreactor with controlled mechanical stimulation: Application in cartilage tissue engineering and beyond

expansion time by 80% [52]. Even low distribution is obtained within each iber [53] and extra-capillary low is supplied by shell ports. A cell-suspension medium is passed through either the extra- or intra-capillary space to provide nutrients with cells seeded inside [54,55], or outside of the ibers [52,56]. HFBs have been successfully used [57-61], and in most experiments, 330 μm, 0.2 μm pore, and 150 μm wall thickness polypropylene hollow ibers are arranged along the axis of high-purity glass tubing, and were held in place with silicon rubber [54–58]. Potter and colleagues obtained a cartilaginous construct with one millimeter thickness after four weeks in an HFB [57]. They are used for MSC expansion [62-65], and Li and colleagues [66,67], found 50-fold expansion within 7 days maintaining self-renewal and multi-lineage differentiation capacity. Nold and colleagues [68], harvested 2-58 million hBMSCs from 8-30 ml of primary, unprocessed bone marrow aspirate maintaining surface antigen expression, differentiation capacity, and immunosuppressive function. A shortcoming is the gradient in both nutrients and products as a consequence of axial pressure gradients leading to heterogeneous distribution of cells and ECM components [69]. Kim and colleagues [61] found signi icantly higher PG content in the region near culture medium in low (45%) as compared to the out low region (24.7%). Another concern is the dif iculty in scaling-up to produce engineered tissue constructs thick enough for in vivo implantation.
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Harnessing developmental processes for vascular engineering and regeneration

Harnessing developmental processes for vascular engineering and regeneration

The vascular network is highly organized and has a distinctive architecture in vivo that is important for its function. Recently, Chen and colleagues generated engineered vessels using a microtissue molding approach to create highly aligned ‘ cords ’ of ECs, which then facilitated the proper formation of new capillaries along the patterned cords (Baranski et al., 2013). The authors used collagen and fibrin hydrogels containing vascular cells, including HUVECs and mouse mesenchymal cells (C3H10T1/2), to create the engineered vasculature. Upon transplantation, the vessels integrated with host blood vessels as early as 3 days and progressively matured for 28 days, demonstrating that implanting cords with a prescribed geometry provides a template for defined neovascular formation in vivo . Such well-defined vascular architecture may help to guide tissue formation in other tissue engineering settings. Indeed, the authors used primary hepatocyte constructs containing either random or organized EC networks and implanted these into mice to assess whether organized vascular architecture can modulate tissue viability. They found that organized engineered vessels enhanced hepatic cell viability and function when compared with randomly distributed vessels, thus demonstrating the significance of multicellular architecture in tissue integration and function. The possibility of creating pre-vascularized tissue constructs is an exciting application of vascular engineering and regeneration. Biomimetic models to simulate angiogenic sprouting morphogenesis in vivo have also been developed using a tissue-molding technique (Morgan et al., 2013; Nguyen et al., 2013). The development of highly organized in vitro vascular constructs also presents a powerful screening platform for studying the effects of different angiogenic factors.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

As technology advances, better methods for fabricating tissues emerge, such as the novel tissue constructs being developed at the Medical University of South Carolina (MUSC) which have the potential to be used as a replacement vessel [3]. In a collaborative effort with MUSC, commercially available macroporous, gelatin microcarriers were seeded with human umbilical vein endothelial cells (HUVECs) and human aortic smooth muscle cells (HASMCs) and dispensed in molds made from agarose. HUVECs and HASMCs are both anchorage dependent cell types, indicating that they must attach to a surface to grow, with the gelatin microcarrier beads acting as a scaffold to seed the cells. The agarose molds are used because agarose is bio-inert and will not allow HUVECs or HASMCs to attach. These conditions allow for the HUVECs and HASMCs to attach only to each other. The result is creation of extracellular matrix and cell-to-cell bridging that results in a tissue construct that can withstand mechanical loading. In fact, recent histological studies provided by our collaborators show the presence of collagen and elastin in the tissue construct [3].
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Novel in vitro respiratory models to study lung development, physiology, pathology and toxicology

Novel in vitro respiratory models to study lung development, physiology, pathology and toxicology

Studies by Cortiella and colleagues in 2006 used engineered lung tissue constructs as a developmental model to examine progenitor cell diff erentiation, res- ponse to growth factors and lung tissue formation. In vitro diff erentiation of a heterogeneous mixture of ovine somatic lung progenitor cells into pulmonary epithelium was performed on polyglycolic acid or pluronic F-127 scaff olds, producing cells expressing Clara cell protein 10, cytokeratin and surfactant protein C by immunostaining, which was validated by western blot for Clara cell protein 10 and surfactant protein C [16]. Scanning electron microscopy of the engi neered tissue constructs demonstrated organization of the cells into pulmonary structures morphologically similar to alveoli. Mondrinos and colleagues used a similar engineered tissue model to examine the diff eren tial eff ects of fi broblast growth factor-2, fi broblast growth factor-7 and fi broblast growth factor-10 on distal lung morphogenesis in collagen gel. Results showed that fi broblast growth factor-2/fi broblast growth factor-7/fi broblast growth factor-10 induced robust budding of the epithelial cell structures, resulting in formation of a uniform endothelial network parallel to the epithelium [17].
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Modeling language constructs with compatibility intervals

Modeling language constructs with compatibility intervals

On the other hand, it seems to be easier to model intensifier “very” for the linguistic interpretation using compatibility intervals. If we would like to do something similar to Zadeh’s concentration (Zadeh, 1972), we could, for example, use a very simple model: for constructs whose compatibility interval starts at the left end of the scale, we could leave the left boundary of the left subinterval unchanged, multiplying all the other boundaries with a certain factor. For constructs whose compatibility interval ends at the right end of the scale, we could do the opposite: leave the right boundary of the right subinterval unchanged, multiplying all the other boundaries with the inverse of the same factor.
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EFFECT OF INTEGRATION OF GREEN CONSTRUCTS AND TRADITIONAL CONSTRUCTS OF BRAND ON GREEN PURCHASE INTENTION OF CUSTOMERS

EFFECT OF INTEGRATION OF GREEN CONSTRUCTS AND TRADITIONAL CONSTRUCTS OF BRAND ON GREEN PURCHASE INTENTION OF CUSTOMERS

little studies in fi eld of green marketing. Bekk et al. (2015) point out that there are only four models proposed on the green brand equity concept. Moreover, the literature on brand equity includes a broader set of meanings and attributes in favor of the customer relationship (Yoo et al., 2000). Four constructs have been investigated by Chen (2010) to analyze the effect of three drivers, namely green brand image, green satisfaction, and green trust, on green brand equity. The positive relationship between these three constructs on green brand equity has been confi rmed. Kang et al. (2012) have suggested fi ve constructs for green brand equity, that is, green satisfaction, green affect, green trust, green brand loyalty, and green brand equity. They have analyzed the effect of these constructs on green brand equity. The results indicate that there exists a positive relationship between green brand loyalty and green brand equity. They also propose that green impact characterized by a positive emotional commitment could set grounds for green loyalty and green brand equity. Perceived green quality, green brand awareness, and green perceived risk have also been analyzed by Chen & Chang (2013) to explore relationships among them. The results indicate a positive and signifi cant relationship between, on the one hand, perceived green quality and green brand awareness and, on the other hand, green brand equity. Furthermore, perceived green quality can negatively affect perceived green risk, which in its own turn can negatively infl uence green brand awareness and green brand equity. Ng et al. (2014) have analyzed the effect of perceived brand quality and brand credibility on consumers’ perception of green brand value, green brand image, and green brand equity. These authors have concluded that perceived brand quality and the overall credibility of a brand have a positive impact on the creation of green image, green perceived value, and equity.
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The factor structure of six salutogenic constructs

The factor structure of six salutogenic constructs

The salutogenic paradigm and its constructs developed from various personality theories emphasising personality growth, wellness and optimal psychological functioning (Antonovsky, 1987; Strümpfer, 1995). From 2000 onwards, many new positive psychology constructs were added to this body of knowledge (Carr, 2004; Frederickson, 2001; Snyder & Lopez, 2002). Positive psychology is defined as the scientific study of ordinary, positive, subjective human strengths, virtues, experiences and functioning (Seligman & Csikszentmihalyi, 2000; Sheldon & King, 2001). In this context, substantial South African research has been reported that focussed on salutogenesis (Strümpfer, 1990), fortigenesis (the origin of strengths – Fouché, 1999; Strümpfer, 1995) and psychofortology (Coetzee & Cilliers, 2001). Positive psychology includes many behavioural constructs such as self-actualisation, sense of coherence, hardiness, potency, self- efficacy, learned resourcefulness, internal locus of control (Strümpfer, 1990), coping (Somerfield & McCrae, 2000), well- being (Lyubomirsky, 2001), creativity and flow (Nakamura & Csikszentmihalyi, 2001; Simonton, 2000), resilience (Masten, 2001), emotional intelligence (Lopez & Snyder, 2003), engagement (Rothmann, 2002), authentic (Seligman, 2003) happiness (Diener, 2000), humour (Fredrickson, 2001), positive affect (Folkman & Moskowitz, 2000), courage, gratitude (Lopez & Snyder, 2003), faith and optimism (Peterson, 2000; Schneider, 2001). In the last six years many of these constructs have been measured and applied in South African organisations, specifically in employee counselling, and individual and
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Year: 2014 Volume: 2 Number: 3

Year: 2014 Volume: 2 Number: 3

The purpose of this study was to illustrate the nature of knowledge exhibited by pre-service mathematics teachers as they approached problems that call for translations. As prospective teachers completed the problems, they (a) moved back and forth between process and object perspectives, (b) infrequently demonstrated constructs of process and object perspectives, and (c) solely demonstrated constructs of object perspectives. A second analysis of data, which aimed to determine the ways in which prospective teachers demonstrated or failed to demonstrate translations, highlighted three conceptions – flexible, disconnected and constrained. With respect to flexible conceptions, prospective teachers demonstrated facets of constructs of process and object perspectives. Fundamentally individuals with flexible conceptions illustrated translations between algebraic and graphical representations. With respect to disconnected conceptions, prospective teachers demonstrated constructs of process and object perspectives, but failed to interpret information regarding both perspectives and or representations. For instance, Katie exhibited this when she failed to coordinate process perspective constructs of the algebraic representations within her solution method to determine appropriate coordinates for ‘C’ and ‘D’. This breakdown in her solution method led her to suggest “you can’t find [C and D] very easily because you don’t know how far over they are going or how far up. I mean for C you can find the ‘x’ – just knowing that it is on the intercept. It will be 0. But you wouldn’t know what the ‘y’ is”. With respect to constrained conceptions, prospective teachers demonstrated constructs of object perspective, but failed to incorporate constructs of process perspective and facets of the algebraic representations. For instance, Marie demonstrated this as she failed to coordinate process perspective constructs of the algebraic representation within her solution methods to determine an appropriate ‘y’ coordinate for point E. This led her to employ approximation methods as she suggested the following: “Since E is (5, y 1 ) we know by looking at the graph that
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Development of a human cardiac organoid injury model reveals innate regenerative potential

Development of a human cardiac organoid injury model reveals innate regenerative potential

A major limitation to studying human cardiac regeneration is the lack of models and tissue samples to study the repair responses of the human heart following injury. To date, a human model of acute cardiac injury has not been achieved. Instead, most research into regeneration following cardiac injury has relied on the use of animal models. hCOs have been proposed as a physiologically relevant model of the human heart (Caspi et al., 2007; Schaaf et al., 2011; Tiburcy et al., 2011), which has a variety of applications from drug screening to studying human cardiac biology. However, hCOs have yet to be applied to meet the demand for an in vitro system to study cardiac regenerative phenomena. To address this problem and provide insight into the endogenous repair processes of the immature human heart, we developed and characterized a human in vitro model of acute cryoinjury. Importantly, our hCO constructs were found to be physiologically representative of the native immature human heart. This finding is consistent with the characterization of other hCO constructs, which were also found to be most comparable with the fetal human heart (Veerman et al., 2015). Remarkably, hCOs were able to completely recover cardiac function following cryoinjury, displaying many of the hallmarks of regenerative neonatal heart tissue.
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The human 230 kD bullous pemphigoid antigen gene (BPAG1)  Exon intron organization and identification of regulatory tissue specific elements in the promoter region

The human 230 kD bullous pemphigoid antigen gene (BPAG1) Exon intron organization and identification of regulatory tissue specific elements in the promoter region

containing a putative tissue specific element, KRE2, which also conferred tissue specificity to the expression of the truncated promoter downstream from this element, however, a mutated derivative of KRE2 was not functional. Detailed knowledge of the structure and regulation of the BPAG1 gene will aid in further elucidation of diseases affecting the cutaneous basement membrane zone.

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Information Quality, Distrust and Perceived Risk as Antecedents of Purchase Intention in the Online Purchase Context

Information Quality, Distrust and Perceived Risk as Antecedents of Purchase Intention in the Online Purchase Context

Therefore, based on the literature and previews studies, it was verified that the relation among information quality, distrust and perceived risk as determinants of purchase intention, as far as is our knowledge, was not empirically tested in any other research model, simultaneously, what is proposed in this study theoretical model and suggests to be tested in a complementary study. Thereby, the constructs approached in this study aim at a better understanding of the antecedents or determinant factors of customers purchase intention. According to the literature (MSI, 2014b), understanding the customer and his consumption experience is a research priority, since there are gaps around customers’ new behavior facing the influence that social media and digital technology exercise over the customer consumption experience. In this vain, this study contributes with the literature about the subject by seeking to understand why customers are willing, or not, to purchase products online, and which the determinant factors for that are.
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Programming constructs for nonprocedural languages

Programming constructs for nonprocedural languages

Abstract: In this paper how a prr:e denotative nonprocedural language based on : the lambda calculus can be provided with purely denotative analogs of the var"ious constr:ucts - such as [r]

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RALA complexed ? TCP nanoparticle delivery to mesenchymal stem cells induces bone formation in tissue engineered constructs in vitro and in vivo

RALA complexed ? TCP nanoparticle delivery to mesenchymal stem cells induces bone formation in tissue engineered constructs in vitro and in vivo

Fig.6: Bone formation in the hydrogels 8 weeks after in vivo implantation. (A) Representative gross morphology (a, c) and µCT images (b, d) of control MSCs (C-MSC) and RALA conjugated TCP treated MSCs (RTCP-MSC) laden alginate hydrogels. (B) Representative images of C-MSC and RTCP-MSC laden alginate hydrogel sections stained with haematoxylin/eosin and alizarin red respectively. (C) Representative gross morphology (e, g) and µCT images (f, g) of C-MSC and RTCP-MSC laden growth factor (GF)-loaded alginate hydrogels. (D) Representative histological images of C-MSC and RTCP-MSC laden GF- loaded alginate hydrogel sections stained with haematoxylins/eosin and alizarin red respectively. (E) Biochemical quantification of collagen content in the hydrogels (n=3). (F) Bone tissue volume quantified from the histological images of the hydrogels (n=5, *P˂ 0.05). (G) Mineral volume quantified using µCT imaging (n=8, *P˂ 0.05). Histology scale bar low magnification 500 µm, high magnification 100 µm.
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Bioprinting of skin constructs for wound healing

Bioprinting of skin constructs for wound healing

In recent years, integration of bioprinting technologies with stem cell research has been an emerging area. Stem cells, such as human bone marrow stem cells, embryonic stem cells (ESCs) and adipose-derived stem cells (ASCs) have been reported to be work as “bioink” directly onto substrates, including the skin regeneration [52–55]. Due to the characteristics of stem cells have multilineage dif- ferentiation potential and self-renewal capacity, subsid- iary structure can be constructed using skin epidermal stem cells such as hair follicles, sweat glands; Stem cells can also be used to regenerate skin tissue to vascular network, the establishment of cells, and cell and tissue biology. Therefore, stem cell has the potential ability to print the real structural and functional integrity of the skin substitute. Stem cell printing has a high cell survival rate, it was reported that the stem cell survival rates before and after 3D bioprinting are 97% and 94%, respectively [56–58], which effectively guarantee the possible usage of this technique for wounds healing.
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Provocations: Raw constructs in mixed media

Provocations: Raw constructs in mixed media

PROVOCATIONS Mixed Media by Raw Constructs in HEINRICH KLINKON A Thesis Report Submitted in Partial Fullfillment of the Requirements for the Degree MASTER OF FINE ARTS MFA Imaging Arts P[r]

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The development of the ‘self directed learning readiness scale in biology’ (SDLRSbio) for pre university biology students

The development of the ‘self directed learning readiness scale in biology’ (SDLRSbio) for pre university biology students

In order to conduct the first round of Delphi technique, a panel consisting of lecturers from medicine, education, teacher training college, and school teachers was formed. The selected panel members had at least 3 years experience in teaching biology related fields. A total of 8 experts were chosen as the panel members. Consent were obtained from the panel prior to conducting the Delphi rounds. Each member of the panel assessed and commented on the scale’s constructs and items independently. Their responses were collected by the researchers for analysis and amendments.
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