Physicochemical characterisation of biosynthetic bacterial cellulose as a potential wound dressing material

The aim of this study was to characterise the physicochemical and biocompatibility properties of biosynthetic bacterial cellulose (BC) as a potential wound dressing material. The moisture content, water vapour transmission rate (WVTR), thermal stability, cyto- and haemo-compatibility of BC were investigated. Results indicated that the physicochemical properties of biosynthetic BC allow an optimum WVTR to be maintained for improved localised wound moisture levels, good thermal stability and excellent water imbibing capabilities. In vitro cytotoxicity and haemocompatibility confirmed the biocompatibility of BC and hence suitability of this material for further exploration into its’ application as a wound dressing material

The Effect of the Source and the Concentration of polymers on the Release of Chlorhexidine from Mucoadhesive Buccal Tablets

In the current work, two groups of chlorhexidine mucoadhesive buccal tablets were prepared, using either rod or irregularly-shaped spherical particles of hydroxypropyl methylcellulose and different ratios of poloxamer 407 (P407). The tablets were designed to release the drug over two hours. Their physicochemical properties and drug release profiles were investigated. The impact on dry granulation, the ex-vivo mucoadhesion, the swelling index, the morphology of swollen tablets and the drug release kinetic were investigated. Drug-polymers chemical interaction was studied using Fourier Transforms Infrared Spectroscopy (FTIR) and differential scanning calorimetry (DSC). Due to different particle shapes, the preparation of dry granules required a 40 KN force for rod-shaped particles compared to 10 KN for the irregularly-shaped spherical particles. All formulations showed at least two-hours residence time using ex-vivo mucoadhesion. Statistically, there was no significant difference in the swelling index, drug release nor its kinetic for both groups. However, the microscopical morphology of the swollen tablet and the size of the pores were affected by particle shape. Increasing the ratio of P407 to 62.5% resulted in a pronounced increase in drug release from around 60% to >90% after two hours. Following the FTIR and DSC analyses, no chemical interaction was noted apart from the steric hindrance effect of P407, which was observed even with the physical mixtures

The Grizzly, November 9, 2023

Vandalism in First Year Dorms • Upcoming Student Engagement Events • Prohibition Era at Bay • UCDC: Motion, Timbre & Rhythm • Word Search • The Most Anticipated Event of Hallows\u27 Eve • 5 Seniors, 1 Team: Leadership On and Off the Court • Iron Sharpens Ironhttps://digitalcommons.ursinus.edu/grizzlynews/2021/thumbnail.jp

A miniaturized bioreactor system for the evaluation of cell interaction with designed substrates in perfusion culture

In tissue engineering, the chemical and topographical cues within three-dimensional (3D) scaffolds are normally tested using static cell cultures but applied directly to tissue cultures in perfusion bioreactors. As human cells are very sensitive to the changes of culture environment, it is essential to evaluate the performance of any chemical, and topographical cues in a perfused environment before they are applied to tissue engineering. Thus the aim of this research was to bridge the gap between static and perfusion cultures by addressing the effect of perfusion on cell cultures within 3D scaffolds. For this we developed a scale down bioreactor system, which allows to evaluate the effectiveness of various chemical and topographical cues incorporated into our previously developed tubular ε-polycaprolactone scaffold under perfused conditions. Investigation of two exemplary cell types (fibroblasts and cortical astrocytes) using the miniaturized bioreactor indicated that: (1) quick and firm cell adhesion in 3D scaffold was critical for cell survival in perfusion culture compared with static culture, thus cell seeding procedures for static cultures might not be applicable. Therefore it was necessary to re-evaluate cell attachment on different surfaces under perfused conditions before a 3D scaffold was applied for tissue cultures, (2) continuous medium perfusion adversely influenced cell spread and survival, which could be balanced by intermittent perfusion, (3) micro-grooves still maintained its influences on cell alignment under perfused conditions, while medium perfusion demonstrated additional influence on fibroblast alignment but not on astrocyte alignment on grooved substrates. This research demonstrated that the mini-bioreactor system is crucial for the development of functional scaffolds with suitable chemical and topographical cues by bridging the gap between static culture and perfusion culture

Valkai András (1540–1586) Báthory-genealógiája. Báthory István király mint az Árpádok leszármazottja

Purpose Heat adaptation (HA) is critical to performance and health in a hot environment. Transition from short-term heat acclimatisation (STHA) to long-term heat acclimatisation (LTHA) is characterised by decreased autonomic disturbance and increased protection from thermal injury. A standard heat tolerance test (HTT) is recommended for validating exercise performance status, but any role in distinguishing STHA from LTHA is unreported. The aims of this study were to (1) define performance status by serial HTT during structured natural HA, (2) evaluate surrogate markers of autonomic activation, including heart rate variability (HRV), in relation to HA status. Methods Participants (n = 13) were assessed by HTT (60-min block-stepping, 50% VO2peak) during STHA (Day 2, 6 and 9) and LTHA (Day 23). Core temperature (Tc) and heart rate (HR) were measured every 5 min. Sampling for HRV indices (RMSSD, LF:HF) and sympathoadrenal blood measures (cortisol, nephrines) was undertaken before and after (POST) each HTT. Results Significant (P < 0.05) interactions existed for Tc, logLF:HF, cortisol and nephrines (two-way ANOVA; HTT by Day). Relative to LTHA, POST results differed significantly for Tc (Day 2, 6 and 9), HR (Day 2), logRMSSD (Day 2 and Day 6), logLF:HF (Day 2 and Day 6), cortisol (Day 2) and nephrines (Day 2 and Day 9). POST differences in HRV (Day 6 vs. 23) were + 9.9% (logRMSSD) and − 18.6% (logLF:HF). Conclusions Early reductions in HR and cortisol characterised STHA, whereas LTHA showed diminished excitability by Tc, HRV and nephrine measures. Measurement of HRV may have potential to aid real-time assessment of readiness for activity in the heat

Nutritional status and the gonadotrophic response to a polar expedition.

Polar expeditions have been associated with changes in the hypothalamic-pituitary-testicular axis consistent with central hypogonadism (i.e., decreased testosterone, luteinising hormone (LH), and follicle stimulating hormone (FSH)). These changes are typically associated with body mass loss. Our aim was to evaluate whether maintenance of body mass during a polar expedition could mitigate against the development of central hypogonadism. Male participants (n = 22) from a 42-day expedition (British Services Antarctic Expedition 2012) volunteered to take part in the study. Body mass, body composition, and strength data were recorded pre- and postexpedition in addition to assessment of serum testosterone, LH, FSH, thyroid hormones, insulin-like growth factor 1 (IGF-1), and trace elements. Energy provision and energy expenditure were assessed at mid- and end-expedition. Daily energy provision was 6335 ± 149 kcal·day(-1). Estimated energy expenditure midexpedition was 5783 ± 1690 kcal·day(-1). Body mass and percentage body fat did not change between pre- and postexpedition. Total testosterone (nmol·L(-1)) (14.0 ± 4.9 vs. 17.3 ± 4.0, p = 0.006), calculated free testosterone (pmol·L(-1)) (288 ± 82 vs. 350 ± 70, p = 0.003), and sex hormone binding globulin (nmol·L(-1)) (33 ± 12 vs. 36 ± 11, p = 0.023) concentrations increased. LH and FSH remained unchanged. Thyroid stimulating hormone (TSH; IU·L(-1)) (2.1 ± 0.8 vs. 4.1 ± 2.1, p < 0.001) and free triiodothyronine (FT3; IU·L(-1)) (5.4 ± 0.4 vs. 6.1 ± 0.8, p < 0.001) increased while free thyroxine, IGF-1, and trace elements remained unchanged. Hand-grip strength was reduced postexpedition but static lift strength was maintained. Maintenance of body mass and nutritional status appeared to negate the central hypogonadism previously reported from polar expeditions. The elevated TSH and free FT3 were consistent with a previously reported "polar T3 syndrome"

Essential oils and metal ions as alternative antimicrobial agents: a focus on tea tree oil and silver.

The increasing occurrence of hospital-acquired infections and the emerging problems posed by antibiotic-resistant microbial strains have both contributed to the escalating cost of treatment. The presence of infection at the wound site can potentially stall the healing process at the inflammatory stage, leading to the development of a chronic wound. Traditional wound treatment regimes can no longer cope with the complications posed by antibiotic-resistant strains; hence, there is a need to explore the use of alternative antimicrobial agents. Pre-antibiotic compounds, including heavy metal ions and essential oils, have been re-investigated for their potential use as effective antimicrobial agents. Essential oils have potent antimicrobial, antifungal, antiviral, anti-inflammatory, antioxidant and other beneficial therapeutic properties. Similarly, heavy metal ions have also been used as disinfecting agents because of their broad spectrum activities. Both of these alternative antimicrobials interact with many different intracellular components, thereby resulting in the disruption of vital cell functions and eventually cell death. This review will discuss the application of essential oils and heavy metal ions, particularly tea tree oil and silver ions, as alternative antimicrobial agents for the treatment of chronic, infected wounds

Characterisation and In Vitro Antimicrobial Activity of Biosynthetic Silver-loaded Bacterial Cellulose Hydrogels

Wounds that remain in the inflammatory phase for a prolonged period of time are likely to be colonised and infected by a range of commensal and pathogenic microorganisms. Treatment associated with these types of wounds mainly focuses on controlling infection and providing an optimum environment capable of facilitating re-epithelialisation, thus promoting wound healing. Hydrogels have attracted vast interest as moist wound-responsive dressing materials. In the current study, biosynthetic bacterial cellulose hydrogels synthesised by Gluconacetobacter xylinus and subsequently loaded with silver were characterised and investigated for their antimicrobial activity against two representative wound infecting pathogens, namely S. aureus and P. aeruginosa. Silver nitrate and silver zeolite provided the source of silver and loading parameters were optimised based on experimental findings. The results indicate that both AgNO3 and AgZ loaded biosynthetic hydrogels possess antimicrobial activity (p < .05) against both S. aureus and P. aeruginosa and may therefore be suitable for wound management applications

The Prismatic Topography of Pinctada maxima Shell Retains Stem Cell Multipotency and Plasticity In Vitro

Abstract The shell of the bivalve mollusc Pinctada maxima is composed of the calcium carbonate polymorphs calcite and aragonite (nacre). Mother‐of‐pearl, or nacre, induces vertebrate cells to undergo osteogenesis and has good osteointegrative qualities in vivo. The calcite counterpart, however, is less researched in terms of the response of vertebrate cells. This study shows that isolation of calcite surface topography from the inherent chemistry allows viable long‐term culture of bone marrow derived mesenchymal stem cells (MSCs). Self‐renewal is evident from the increased gene expression of the self‐renewal markers CD63, CD166, and CD271 indicating that cells cultured on the calcite topography maintain their stem cell phenotype. MSCs also retain their multipotency and can undergo successful differentiation into osteoblasts and adipocytes. When directed to adipogenesis, MSCs cultured on prism replicas are more amenable to differentiation than MSCs cultured on tissue culture polystyrene indicating a higher degree of plasticity in MSCs growing on calcite P. maxima prismatic topography. The study highlights the potential of the calcite topography of P. maxima as a biomimetic design for supporting expansion of MSC populations in vitro, which is of fundamental importance if it meets the demands for autologous MSCs for therapeutic use

Accelerated neuritogenesis and maturation of primary spinal motor neurons in response to nanofibers

Neuritogenesis, neuronal polarity formation, and maturation of axons and dendrites are strongly influenced by both biochemical and topographical extracellular components. The aim of this study was to elucidate the effects of polylactic acid electrospun fiber topography on primary motor neuron development, because regeneration of motor axons is extremely limited in the central nervous system and could potentially benefit from the implementation of a synthetic scaffold to encourage regrowth. In this analysis, we found that both aligned and randomly oriented submicron fibers significantly accelerated the processes of neuritogenesis and polarity formation of individual cultured motor neurons compared to flat polymer films and glass controls, likely due to restricted lamellipodia formation observed on fibers. In contrast, dendritic maturation and soma spreading were inhibited on fiber substrates after 2 days in vitro . This study is the first to examine the effects of electrospun fiber topography on motor neuron neuritogenesis and polarity formation. Aligned nanofibers were shown to affect the directionality and timing of motor neuron development, providing further evidence for the effective use of electrospun scaffolds in neural regeneration applications. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 589–603, 2010Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77438/1/20792_ftp.pd