Development and Characterization of Photocrosslinkable Hyaluronic Acid Hydrogels for Cartilage Regeneration

Damage to cartilage from general wear, disease, or injury can lead to joint pain and tissue degeneration. With its limited ability for self-repair, cartilage has become a target for tissue engineering (TE). As current treatments have yet to provide long-term functional cartilage repair, this dissertation introduces the development and use of photopolymerizable hyaluronic acid (HA) based hydrogels for TE to optimize cellular interactions and neocartilage formation. By altering hydrogel design parameters (e.g., molecular weight and macromer concentration), a wide range of hydrogel properties were obtained. These hydrogels all preserved the rounded morphology of chondrocytes, but cell viability and neocartilage formation were dependent on hydrogel design, where increased crosslinking resulted in cell death and increased macromer molecular weight yielded inhomogeneities in cell and ECM distribution within the hydrogel. These variables also influenced the formed neocartilage properties. The ability of HA hydrogels to promote neocartilage formation was also dependent on cell source and culture. The expansion of chondrocytes in 2D in vitro affected neocartilage formation in HA hydrogels after the second passage, as construct properties further decreased with continued passage. Chondrocytes from different tissue sources also behaved variably in the hydrogels; auricular chondrocytes excelled in static culture and subcutaneous culture over articular chondrocytes, while articular chondrocytes were stimulated in a mechanically loaded environment. As the use of chondrocytes for cartilage TE is limited clinically, we turned to mesenchymal stem cells (MSCs). In vitro culture of MSC-laden HA hydrogels demonstrated that these HA hydrogels not only supported, but enhanced chondrogenesis when compared to relatively inert hydrogels, potentially due to receptor interactions with HA. However, in these hydrogels, ECM was localized to pericellular regions. To accelerate the diffusion and distribution of ECM proteins, hydrolytically degradable HA macromers were synthesized to create a dynamic environment. When degradation complemented ECM deposition, ECM distribution and ultimately the functional maturation of the construct were improved. While this dissertation focused on material development to improve cartilage regeneration, growth factor delivery optimization and successful implementation of these hydrogels in cartilage defect models remain, towards our goal of a successful long-term repair solution to cartilage damage

Tuning hydrogel properties for applications in tissue engineering

Biomaterial design is an important component towards tissue engineering applications. There are many parameters that may be adjusted including physical properties (i.e., degradation and mechanics) and chemical properties (e.g., adhesion and cellular interactions). These design components may dictate the success or failure of a tissue engineering approach. Our group is particularly interested in the use of swollen hydrogels as cell carriers. One material that is used to fabricate hydrogels is hyaluronic acid (HA), which is found in many tissues in the body. Here, we show the control over hydrogel degradation, both in the bulk and locally to cells to control both the distribution of extracellular matrix by cells and whether or not a cell spreads in the hydrogels. These signals are important in the final structure and mechanical properties of engineered tissues, and potentially the differentiation of encapsulated stem cells

Regular consumption of HolisFiit, a polyphenol-rich extract-based food supplement, improves mind and body well-being of overweight and slightly obese volunteers: a randomized, double-blind, parallel trial.

Modern lifestyles face growing demands for natural solutions to help improve general well-being. Accordingly, mind-body activities such as yoga have considerably grown. However, beneficial effects require regular workout. Besides, literature suggests that polyphenols may demonstrate positive effects on both mental and physical health. Overweight and obese volunteers, for which well-being might be perceived degraded, were included in a 16-week double-blind, randomized and parallel trial with a daily supplementation of HolisFiit®, a polyphenol-rich food supplement. Body composition was assessed by dual-energy X-ray absorptiometry (DXA) technology; well-being was evaluated with both, Athens Insomnia Scale (AIS) and components from Short Form-36 questionnaire (SF-36). Body composition significantly rebalanced by 7.7% (p = .019) of the lean-to-fat mass ratio. Also, sleep quality significantly improved by 43% (p = .00015) as well as both physical and mental components from SF-36, respectively by 10% (p = .004) and 7% (p = .021). These data altogether, suggest that regular consumption of HolisFiit®, might significantly improve mind and body well-being.Actividad Física y Deport

Identity brand avoidance: How is it manifested in social media?

Existing research on brand symbolic consumption mainly focuses on brand approach; the phenomenon being explained by the theory of self congruity, i.e. consumers would approach brands whose image is congruent to their actual or ideal self. On the other hand, identity brand avoidance, has been object of less attention. The scarce research dedicated to this field essentially revolves around the causes of identity brand avoidance, i.e. when consumers have a positive image of themselves and a negative image of a brand, they would avoid the brand. This paper sheds the light on manifestation of identity brand avoidance on social media, namely how consumers express the discrepancy they hold with a brand in an environment where they can easily express themselves, gather with their peers, educate each other, and even act against a brand. Three main themes of identity brand avoidance emerge from the study: identity brand avoidance for identity acquisition purposes, identity brand avoidance to maintain an identity and identity brand avoidance to protect an identity

Movement Guidelines for Young Children: Engaging Stakeholders to Design Dissemination Strategies in the Hong Kong Early Childhood Education Context

Background Early childhood is a critical period during which patterns of movement behaviors are formed. The World Health Organization had endorsed guidelines for physical activity, sedentary behavior and sleep over a 24-h time period, which had been adopted by the Center for Health Protection of Hong Kong. This paper reports on stakeholder engagements that were conducted to inform the design of strategies to disseminate the guidelines in early childhood education (ECE) settings. Methods Using a mixed-methods study design, we sought to (a) assess the stakeholders\u27 levels of awareness and knowledge of the Hong Kong movement guidelines for young children and (b) identify the factors that influence the uptake of the said guidelines. We conducted an online survey of early childhood education teachers (N =314), twelve focus groups involving teachers (N = 18) and parents (N = 18), and individual interviews of key informants (N = 7) and domestic workers who provide care for preschool-aged children (N = 7). Descriptive statistics were used for the quantitative data, and thematic analysis was performed on the qualitative data using an inductive and semantic approach following a realist framework. Findings Our findings show that teachers were aware of the movement guidelines for young children, but their knowledge of the specific guidelines was deficient; parents and domestic workers had limited awareness and knowledge of the guidelines. Uptake of the movement guidelines is enabled by parent engagement, activities in the ECE centers, home-school cooperation, and community activities for children. The challenges include the time poverty of parents, local curriculum requirements, limited physical spaces, social values, and pandemic-related restrictions. Conclusion We recommend that dissemination strategies in the ECE context should deliver knowledge content and support stakeholders in mitigating the challenges associated with time, space, and social conditions

Evaluation of a School-Based Dissemination of the Movement Guidelines for Young Children in Hong Kong: Study Protocol

Background Healthy movement behaviors in early childhood are believed to track to adulthood, potentially imparting protective benefits against non-communicable diseases. Highlighting the collaborative and complementary roles of parents and educators in promoting health of young children, this study aims to enable parents and teachers to successfully promote healthy movement behaviors in young children. Guidelines for physical activity, sedentary screen time, and sleep of children aged 2 to 6 years will be systematically disseminated to parents and teachers of children enrolled in early childhood education centers (ECECs) in Hong Kong. An evaluation will be conducted to assess the implementation process and the outcomes of the dissemination of said guidelines. Methods The evaluation will include formative and summative components to examine the implementation (i.e., process evaluation) and the outcomes (i.e., outcome evaluation). Participants include teachers, parents, and children from ECECs in Hong Kong. The process evaluation will be guided by the RE-AIM framework (i.e., reach, efficacy, adaptation, implementation, maintenance). Data gathering and analysis will take a mixed-methods triangulation design - convergence model. The outcome evaluation consists of a non-randomized observational study, using quantitative data from questionnaires and accelerometers. The primary outcome to be measured is the extent to which children meet the guidelines for physical activity, sedentary screen time, and sleep; the secondary outcome is teachers’ and parents’ knowledge and awareness of the guidelines. Discussion Young children who engage in healthy movement behaviors are likely to become adults who will have the disposition to engage in behaviors that have protective effects against non-communicable diseases. The findings of this evaluation are expected to contribute to improving the strategies of systems and government agencies that aspire to promote healthy movement behaviors of young children

The Effect of Race, Sex, and Insurance Status on Time-to-Listing Decisions for Liver Transplantation

Fair allocation of organs to candidates listed for transplantation is fundamental to organ-donation policies. Processes leading to listing decisions are neither regulated nor understood. We explored whether patient characteristics affected timeliness of listing using population-based data on 144,507 adults hospitalized with liver-related disease in Pennsylvania. We linked hospitalizations to other secondary data and found 3,071 listed for transplants, 1,537 received transplants, and 57,020 died. Among candidates, 61% (n = 1,879) and 85.5% (n = 2,626) were listed within 1 and 3 years of diagnosis; 26.7% (n = 1,130) and 95% (n = 1,468) of recipients were transplanted within 1 and 3 years of listing. Using competing-risks models, we found few overall differences by sex, but both black patients and those insured by Medicare and Medicaid (combined) waited longer before being listed. Patients with combined Medicare and Medicaid insurance, as well as those with Medicaid alone, were also more likely to die without ever being listed. Once listed, the time to transplant was slightly longer for women, but it did not differ by race/ethnicity or insurance. The early time period from diagnosis to listing for liver transplantation reveals unwanted variation related to demographics that jeopardizes overall fairness of organ allocation and needs to be further explored

Isolation and identification of indigenous biosurfactants producing bacteria from motor oil / Ang Chung Huap, Cindy Tan Soo Yun and Millaa-Armilla Asli

A biosurfactant is a type of complex bio-based material that is produced by microorganisms which have the ability to lower the surface and interfacial tensions of liquids. Being amphiphilic molecules, the polar moiety (hydrophilic) consists of carbohydrate, amino acid or phosphate group. Meanwhile, the hydrophobic (nonpolar) parts are usually long carbon chains and fatty acids. They accumulate between fluid phases, can form micelles and thereby enhance the solubility of poorly soluble compounds in water. Various microbial surfactants have been successfully produced using different types of water soluble and insoluble carbon sources including crude petroleum and motor lubrication oils. This study aims to screen and identify indigenous bacterial strains isolated from motor oil contaminated soil samples which are capable of synthesizing microbial surfactants. Motor oils consist of aliphatic and aromatic hydrocarbons such as naphthalene, benz(a)anthracene, benzo(a)pyrene, and fluoranthene. Furthermore, used motor oils also contain heavy metals such as zinc, magnesium, barium, lead, aluminium, chromium, copper, iron, nikel, silicon, and tin. All these elements can cause severe environmental pollutions when used motor oils leaks onto earth surface. The biosurfactants producing bacteria will be identified using standard morphological method and DNA sequencing method. DNA sequencing of bacterial 16S rRNA region amplified by universal primers will provide an accurate identification result within shorter time. In addition, biosurfactants produced by the indigenous bacteria will also be tested for additional potential usages such as surface tension reduction and antimicrobial properties. The biosurfactants are favoured than chemical surfactants owing to their low toxicity, biodegradability, mild production conditions that use cheap waste substrates and are versatile at extreme salinity, temperature and pH. Major applications of biosurfactants include enhanced oil recovery, degradation of hydrocarbons and removal of pesticides as well as in the healthcare and food processing industries

Supplementation with a Polyphenol-Rich Extract, TensLess® , Attenuates Delayed Onset Muscle Soreness and Improves Muscle Recovery from Damages After Eccentric Exercise.

High-intensity exercises are known to provoke delayed onset muscle soreness (DOMS). Delayed onset muscle soreness typically occurs within the first 24 h, peaks between 24 and 72 h, and can last as long as 5-7 days post-exercise. Delayed onset muscle soreness is a multifactorial process involving both mechanical and biochemical components, associated with clinical features that may limit range of motion, and athletes seek for effective recovery strategies to optimize future training sessions. TensLess® is a food supplement developed to help manage post-exercise recovery. The supplement has been investigated on 13 recreationally active athletes of both sex, during a randomized, double-blind, and crossover clinical investigation, including a 3-week washout period. The clinical investigation was based on the study of TensLess® effects for DOMS management and on the reduction of associated muscle damages following an eccentric exercise protocol. Supplementation with TensLess® induced significant decrease in DOMS perception (-33%; p = 0.008) as of the first 24 h; this was significantly correlated with a lowered release of muscle damage-associated biomarkers, namely myoglobin, creatinine, and creatine kinase, for the whole length of the recovery period. Taken together, these positive results clearly indicate that post-exercise supplementation with TensLess® may preserve myocytes and reduce soreness following eccentric exercise-induced damages, and, accordingly, significantly shorten muscle recovery.Actividad Física y Deport