Into the wild: uncertain frontiers and sustainable human-nature interactions.

Humans seldom consider themselves as animals, and that humans are animals is a truth frequently turned into an insulting metaphor indicating "uncivilized" behavior in many cultures. Interestingly, the "civilizing" aspects of Western Culture in the Global North are historically derived from traditions of democracy based on living in cities from which the wild has been banished. This is embedded in the English language since civilizing and civilization come from the Latin for city, civitas, the place where citizens hold voting rights. Beyond the gates of civilization is the wild. How the wild and nature have been constructed and demarcated is an enormously complex and enduring challenge in western philosophy as it relates to knowledge-making, existence, truth, and reality. Indeed, whilst people generally believe they know what nature means, they rarely realize that little in nature is wild. Furthermore, the concept of uncertainty, central to the pandemic, is compounded by climate instability and a potentially disastrous future. This is breaking down what is known, requiring porous and flexible conceptual frontiers and a transdisciplinary approach. This article traces the linguistic separation of humans from their animal origins and wilder environments for political and increasingly greedy economic purposes. It explores the acknowledged complexity of healthy human-nature interactions, juxtaposing information mainly from the humanities and social sciences. Demonstrating how unhealthy the current paradigm has proven to be for humans and the natural world, it brings together conflicting information to disrupt traditional certainties using an innovative bricolage methodology. It weaves and combines different ways of knowing as it considers forms of knowledge-making, rewilding, foraging, the place of magical thinking, and vital force. It concludes that a new paradigm is needed to enable a way of working toward any vision of healthy human-nature interaction.

A Rare Case of Candida parapsilosis Lumbar Discitis With Osteomyelitis.

Fungal osteomyelitis is rare and usually seen in immunocompromised patients. We report a case of Candida parapsilosis osteomyelitis in an immunocompetent patient with no prior surgical history. He went for spinal laminectomy with debridement and drainage. Intraoperative culture grew C. parapsilosis, and the patient was treated with fluconazole.

Effects of physical or fenceline boar exposure and exogenous gonadotropins on puberty induction and subsequent fertility in gilts.

The present study was part of a larger experiment that evaluated litter of origin effects on gilt production. The objectives of this study were to determine the effect of physical or fenceline boar exposure and exogenous gonadotropins on puberty induction and subsequent fertility in a commercial farm environment. The experiment was performed in three replicates. Prepubertal gilts were assigned by pen (13/pen) to receive 15 min of daily Fenceline (FBE, n = 153) or Physical (PBE, n = 154) Boar Exposure (BE) for 3 weeks starting at 184 d of age in a purpose-designed Boar Exposure Area (BEAR). At the start of week 3, prepubertal gilts were randomly assigned to receive PG600 or none (Control). From weeks 4 to 6, estrus was checked using only FBE. During weeks 1 to 3, measures of reproductive status were obtained weekly or until expression of estrus. Upon detection of first estrus, gilts were relocated into stalls and inseminated at second estrus. PBE reduced age (P = 0.001) and days to puberty (P = 0.002), increased the proportion of gilts in estrus (P = 0.04) in week 1 (38.3 vs. 27.5%), and tended (P = 0.08) to improve estrus in week 2 (37.6 vs. 26.1%) compared to FBE, respectively. In week 3, more prepubertal gilts receiving PBE-PG600 exhibited estrus (P = 0.04; 81.8%) compared to PBE-Control (40.3%), FBE-PG600 (56.4%), and FBE-Control (47.8%). Overall, expression of estrus through week 6 tended (P = 0.08) to be greater for PBE than FBE (91.5 vs. 85.0%). PBE increased (P ≤ 0.05) or tended to increase (P > 0.05 and ≤0.10) service and farrowing rates in parities 1 through 4, but within parity, there were no effects (P > 0.10) on pig production or wean to service interval. Analyses also indicated that weeks from start of boar exposure to puberty, litter of origin traits, and follicle measures at puberty were related to the subsequent fertility. The results of this study confirm the advantages of using increased intensity of boar exposure, combined with PG600 treatment, for effective induction of pubertal estrus in a commercial setting.

A Review of the Use of Microparticles for Cartilage Tissue Engineering.

Tissue and organ failure has induced immense economic and healthcare concerns across the world. Tissue engineering is an interdisciplinary biomedical approach which aims to address the issues intrinsic to organ donation by providing an alternative strategy to tissue and organ transplantation. This review is specifically focused on cartilage tissue. Cartilage defects cannot readily regenerate, and thus research into tissue engineering approaches is relevant as a potential treatment option. Cells, scaffolds, and growth factors are three components that can be utilized to regenerate new tissue, and in particular recent advances in microparticle technology have excellent potential to revolutionize cartilage tissue regeneration. First, microspheres can be used for drug delivery by injecting them into the cartilage tissue or joint space to reduce pain and stimulate regeneration. They can also be used as controlled release systems within tissue engineering constructs. Additionally, microcarriers can act as a surface for stem cells or chondrocytes to adhere to and expand, generating large amounts of cells, which are necessary for clinically relevant cell therapies. Finally, a newer application of microparticles is to form them together into granular hydrogels to act as scaffolds for tissue engineering or to use in bioprinting. Tissue engineering has the potential to revolutionize the space of cartilage regeneration, but additional research is needed to allow for clinical translation. Microparticles are a key enabling technology in this regard.

Advanced Methods for the Characterization of Supramolecular Hydrogels.

With the increased research on supramolecular hydrogels, many spectroscopic, diffraction, microscopic, and rheological techniques have been employed to better understand and characterize the material properties of these hydrogels. Specifically, spectroscopic methods are used to characterize the structure of supramolecular hydrogels on the atomic and molecular scales. Diffraction techniques rely on measurements of crystallinity and help in analyzing the structure of supramolecular hydrogels, whereas microscopy allows researchers to inspect these hydrogels at high resolution and acquire a deeper understanding of the morphology and structure of the materials. Furthermore, mechanical characterization is also important for the application of supramolecular hydrogels in different fields. This can be achieved through atomic force microscopy measurements where a probe interacts with the surface of the material. Additionally, rheological characterization can investigate the stiffness as well as the shear-thinning and self-healing properties of the hydrogels. Further, mechanical and surface characterization can be performed by micro-rheology, dynamic light scattering, and tribology methods, among others. In this review, we highlight state-of-the-art techniques for these different characterization methods, focusing on examples where they have been applied to supramolecular hydrogels, and we also provide future directions for research on the various strategies used to analyze this promising type of material.

High-Resolution Bioprinting of Recombinant Human Collagen Type III.

The development of commercial collagen inks for extrusion-based bioprinting has increased the amount of research on pure collagen bioprinting, i.e., collagen inks not mixed with gelatin, alginate, or other more common biomaterial inks. New printing techniques have also improved the resolution achievable with pure collagen bioprinting. However, the resultant collagen constructs still appear too weak to replicate dense collagenous tissues, such as the cornea. This work aims to demonstrate the first reported case of bioprinted recombinant collagen films with suitable optical and mechanical properties for corneal tissue engineering. The printing technology used, aerosol jet® printing (AJP), is a high-resolution printing method normally used to deposit conductive inks for electronic printing. In this work, AJP was employed to deposit recombinant human collagen type III (RHCIII) in overlapping continuous lines of 60 µm to form thin layers. Layers were repeated up to 764 times to result in a construct that was considered a few hundred microns thick when swollen. Samples were subsequently neutralised and crosslinked using EDC:NHS crosslinking. Nanoindentation and absorbance measurements were conducted, and the results show that the AJP-deposited RHCIII samples possess suitable mechanical and optical properties for corneal tissue engineering: an average effective elastic modulus of 506 ± 173 kPa and transparency ≥87% at all visible wavelengths. Circular dichroism showed that there was some loss of helicity of the collagen due to aerosolisation. SDS-PAGE and pepsin digestion were used to show that while some collagen is degraded due to aerosolisation, it remains an inaccessible substrate for pepsin cleavage.

3D bioprinting of molecularly engineered PEG-based hydrogels utilizing gelatin fragments.

Three-dimensional (3D) bioprinting is an additive manufacturing process in which the combination of biomaterials and living cells, referred to as a bioink, is deposited layer-by-layer to form biologically active 3D tissue constructs. Recent advancements in the field show that the success of this technology requires the development of novel biomaterials or the improvement of existing bioinks. Polyethylene glycol (PEG) is one of the well-known synthetic biomaterials and has been commonly used as a photocrosslinkable bioink for bioprinting; however, other types of cell-friendly crosslinking mechanisms to form PEG hydrogels need to be explored for bioprinting and tissue engineering. In this work, we proposed micro-capillary based bioprinting of a novel molecularly engineered PEG-based bioink that transiently incorporates low molecular weight gelatin (LMWG) fragments. The rheological properties and release profile of the LMWG fragments were characterized, and their presence during hydrogel formation had no effect on the swelling ratio or sol fraction when compared to PEG hydrogels formed without the LMWG fragments. For bioprinting, PEG was first functionalized with cell-adhesive RGD ligands and was then crosslinked using protease-sensitive peptides via a Michael-type addition reaction inside the micro-capillary. The printability was assessed by the analysis of extrudability, shape fidelity, and printing accuracy of the hydrogel filaments after the optimization of the gelation conditions of the PEG-based bioink. The LMWG fragments supplemented into the bioink allowed the extrusion of smooth and uniform cylindrical strands of the hydrogel and improved shape fidelity and printing accuracy. Encapsulated cells in both bioprinted and non-bioprinted PEG-based hydrogels showed high viability and continued to proliferate over time in culture with a well-defined cell morphology depending on the presence of the cell adhesive peptide RGD. The presented micro-capillary based bioprinting process for a novel PEG-based bioink can be promising to construct complex 3D structures with micro-scale range and spatiotemporal variations without using any cytotoxic photoinitiator, UV light, or polymer support.

Chlorite oxidized oxyamylose differentially influences the microstructure of fibrin and self assembling peptide hydrogels as well as dental pulp stem cell behavior.

Tailored hydrogels mimicking the native extracellular environment could help overcome the high variability in outcomes within regenerative endodontics. This study aimed to evaluate the effect of the chemokine-binding and antimicrobial polymer, chlorite-oxidized oxyamylose (COAM), on the microstructural properties of fibrin and self-assembling peptide (SAP) hydrogels. A further goal was to assess the influence of the microstructural differences between the hydrogels on the in vitro behavior of human dental pulp stem cells (hDPSCs). Structural and mechanical characterization of the hydrogels with and without COAM was performed by atomic force microscopy and scanning electron microscopy to characterize their microstructure (roughness and fiber length, diameter, straightness, and alignment) and by nanoindentation to measure their stiffness (elastic modulus). Then, hDPSCs were encapsulated in hydrogels with and without COAM. Cell viability and circularity were determined using confocal microscopy, and proliferation was determined using DNA quantification. Inclusion of COAM did not alter the microstructure of the fibrin hydrogels at the fiber level while affecting the SAP hydrogel microstructure (homogeneity), leading to fiber aggregation. The stiffness of the SAP hydrogels was sevenfold higher than the fibrin hydrogels. The viability and attachment of hDPSCs were significantly higher in fibrin hydrogels than in SAP hydrogels. The DNA content was significantly affected by the hydrogel type and the presence of COAM. The microstructural stability after COAM inclusion and the favorable hDPSCs' response observed in fibrin hydrogels suggest this system as a promising carrier for COAM and application in endodontic regeneration.

Medical Malpractice in Nerve Injury of the Upper Extremity.

Background: Medical malpractice accounts for more than $55 billion of annual health care costs. Updated malpractice risk to surgeons and physicians related to upper extremity peripheral nerve injury has not been published. Methods: A comprehensive database analysis of upper extremity nerve injury claims between 1995 and 2014 in the United States was conducted using the Medical Professional Liability Association Data Sharing Project, representing 24 major insurance companies. Results: Nerve injury in the upper extremity accounted for 614 (0.3%) malpractice claims (total of 188 323). Common presenting diagnoses included carpal tunnel syndrome (41%), upper extremity fractures (19%), and traumatic nerve injuries to the shoulder or upper limb (8%). Improper performance (49% of total claims) and claims without evidence of medical error (19%) were the most common malpractice suits. Orthopedic surgeons were the most frequently targeted specialists (42%). In all, 65% of nerve injury claims originated from operative procedures in a hospital, 59% of claims were dismissed or withdrawn prior to trial, and 30% resulted in settlements. Thirty-three percent of claims resulted in an indemnity payment to an injured party, with an average payout of $203 592 per successful suit. Only 8% of claims resulted in a completed trial and verdict, and verdicts were overwhelmingly in favor of the defendant (83%). Conclusions: Most malpractice claims from peripheral nerve injuries in the United States arise from the management of common diagnoses, occur in the operating room, and allege improper performance. Strategies to reduce malpractice risk should emphasize the management of common conditions and patient-physician communication.

Associations among individual gilt birth weight, litter birth weight phenotype, and the efficiency of replacement gilt production.

Selection for larger litter size has increased the number of low individual birth weight (BWi) pigs and produced sows with a repeatable low average litter birth weight phenotype (BWP). Using an average of 3.6 litters records per sow, BWP was established in 644 nucleus-multiplication sows producing replacement gilts in a large commercial operation and classified as low (L-BWP, <1.18 kg, n = 85), medium (M-BWP, ≥1.18 to ≤1.35 kg, n = 250), or high (H-BWP, >1.35 kg, n = 309) on the basis of a BWi of 1.18 kg below which there was a high risk of early mortality and the average BWi (1.35 kg) for the population. In subsequent litters, potential replacement gilts born to these sows (n = 7,341) received a unique identification tag that allowed the impact of BWi, BWP, and their interactions on the efficiency of replacement gilt production to be evaluated. Negative effects of BWi on mortality until day 4 after birth were confirmed (P < 0.05) and cumulative losses to weaning, to day 70 of age, and to final pre-selection at 165 d of age were affected (P ≤ 0.05) by the interaction between BWP and BWi. Among the 2,035 gilts for which records for selection efficiency and production to fourth parity were available, a lower BWi decreased the probability of gilts reaching pubertal estrus (P < 0.05) after 21 and 28 d of boar stimulation starting at 180 d of age, with no effect of BWP. Overall, neither BWi, BWP, nor their interaction affected age at puberty. After breeding, only the main effect of BWP affected productivity and retention in the sow herd. In parities 1 and 2, percent stillborn was higher in litters born to gilts from H-BWP compared with L-BWP dams (P < 0.05), and in parity 2, total born and born alive were lower in sows derived from H-BWP compared with other BWPs. There were no differences in retention based on BWP classes until parity 2, after which retention tended (P ≤ 0.09) to be lower in sows derived from H-BWP compared with L-BWP dams. These results provide evidence that sow BWP is an important factor in the overall efficiency of replacement gilt management. This study also confirms that effective gilt selection and pre-breeding management protocols support excellent sow lifetime productivity and mitigate the risk of a high BWP in the litter of origin affecting retention in the breeding herd.

Towards Mimicking the Fetal Liver Niche: The Influence of Elasticity and Oxygen Tension on Hematopoietic Stem/Progenitor Cells Cultured in 3D Fibrin Hydrogels.

Hematopoietic stem/progenitor cells (HSPCs) are responsible for the generation of blood cells throughout life. It is believed that, in addition to soluble cytokines and niche cells, biophysical cues like elasticity and oxygen tension are responsible for the orchestration of stem cell fate. Although several studies have examined the effects of bone marrow (BM) niche elasticity on HSPC behavior, no study has yet investigated the effects of the elasticity of other niche sites like the fetal liver (FL), where HSPCs expand more extensively. In this study, we evaluated the effect of matrix stiffness values similar to those of the FL on BM-derived HSPC expansion. We first characterized the elastic modulus of murine FL tissue at embryonic day E14.5. Fibrin hydrogels with similar stiffness values as the FL (soft hydrogels) were compared with stiffer fibrin hydrogels (hard hydrogels) and with suspension culture. We evaluated the expansion of total nucleated cells (TNCs), Lin-/cKit+ cells, HSPCs (Lin-/Sca+/cKit+ (LSK) cells), and hematopoietic stem cells (HSCs: LSK- Signaling Lymphocyte Activated Molecule (LSK-SLAM) cells) when cultured in 5% O2 (hypoxia) or in normoxia. After 10 days, there was a significant expansion of TNCs and LSK cells in all culture conditions at both levels of oxygen tension. LSK cells expanded more in suspension culture than in both fibrin hydrogels, whereas TNCs expanded more in suspension culture and in soft hydrogels than in hard hydrogels, particularly in normoxia. The number of LSK-SLAM cells was maintained in suspension culture and in the soft hydrogels but not in the hard hydrogels. Our results indicate that both suspension culture and fibrin hydrogels allow for the expansion of HSPCs and more differentiated progeny whereas stiff environments may compromise LSK-SLAM cell expansion. This suggests that further research using softer hydrogels with stiffness values closer to the FL niche is warranted.

Supercharge End-to-Side Anterior Interosseous-to-Ulnar Motor Nerve Transfer Restores Intrinsic Function in Cubital Tunnel Syndrome.

BACKGROUND: The supercharge end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer offers a viable option to enhance recovery of intrinsic function following ulnar nerve injury. However, in the setting of chronic ulnar nerve compression where the timing of onset of axonal loss is unclear, there is a deficit in the literature on outcomes after supercharge end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer. METHODS: A retrospective study of patients who underwent supercharge end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer for severe cubital tunnel syndrome over a 5-year period was performed. The primary outcomes were improvement in first dorsal interosseous Medical Research Council grade at final follow-up and time to reinnervation. Change in key pinch strength; grip strength; and Disabilities of the Arm, Shoulder and Hand questionnaire scores were also evaluated using paired t tests and Wilcoxon signed rank tests. RESULTS: Forty-two patients with severe cubital tunnel syndrome were included in this study. Other than age, there were no significant clinical or diagnostic variables that were predictive of failure. There was no threshold of compound muscle action potential amplitude below which supercharge end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer was unsuccessful. CONCLUSIONS: This study provides the first cohort of outcomes following supercharge end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer in chronic ulnar compression neuropathy alone and underscores the importance of appropriate patient selection. Prospective cohort studies and randomized controlled trials with standardized outcome measures are required. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Engineered Three-Dimensional Microenvironments with Starch Nanocrystals as Cell-Instructive Materials.

Naturally, cells reside in three-dimensional (3D) microenvironments composed of biopolymers that guide cellular behavior via topographical features as well as through mechanical and biochemical cues. However, most studies describing the influence of topography on cells' behavior are performed on rigid and synthetic two-dimensional substrates. To design systems that more closely resemble native microenvironments, herein we develop 3D nanocomposite hydrogels consisting of starch nanocrystals (SNCs) embedded in a gelatin matrix. The incorporation of different concentrations of SNCs (0.05, 0.2, and 0.5 wt %) results in an increase of compressive modulus when compared to hydrogels without SNCs, without affecting the swelling ratio, thus providing a tunable system. Confirming the cytocompatibility of the novel composites, the viability of encapsulated L929 fibroblasts is >90% in all hydrogels. The cellular metabolic activity and DNA content are similar for all formulations and increase over time, indicating that the fibroblasts proliferate within the hydrogels. After 4 d of culture, Live/Dead staining and F-actin/nuclei staining show that the encapsulated fibroblasts develop an elongated morphology in the hydrogels. On the other hand, encapsulated chondrogenic progenitor ATDC5 cells also maintain a viability around 90% but display a round morphology, especially in the hydrogels with SNCs, indicating a potential application of the materials for cartilage tissue engineering. We believe that topographical and mechanical cues within 3D microenvironments can be a powerful tool to instruct cells' behavior and that the developed gelatin/SNC nanocomposite warrants further study.

Gilt Management for Fertility and Longevity.

Substantial evidence supports successful management of gilts as an absolutely necessary component of breeding herd management and the pivotal starting point for the future fertility and longevity of the breeding herd. Therefore, gilt management practices from birth have the potential to influence the future reproductive performance of the sow herd. A good gilt management program will address several key components such as birth traits that determine the efficiency of replacement gilt production; effective selection of the most fertile gilts for entry to the breeding herd; effective management programs that provide a consistent supply of service eligible gilts; and appropriate management of weight, physiological maturity, and a positive metabolic state at breeding. Good gilt management can largely resolve the existing gap between excellent genetic potential and the more modest sow lifetime productivity typically achieved in the industry. Investment in good gilt development programs from birth represents a foundational opportunity for improving the efficiency of the pork production industry.

Robust scalable synthesis of a bis-urea derivative forming thixotropic and cytocompatible supramolecular hydrogels.

Synthetic hydrogels address a need for affordable, industrially scalable scaffolds for tissue engineering. Herein, a novel low molecular weight gelator is reported that forms self-healing supramolecular hydrogels. Its robust synthesis can be performed in a solvent-free manner using ball milling. Strikingly, encapsulated cells spread and proliferate without specific cell adhesion ligands in the nanofibrous material.

Cytocompatible carbon nanotube reinforced polyethylene glycol composite hydrogels for tissue engineering.

Hydrogels are attractive materials for stimulating 3D cell growth and tissue regeneration, and they provide mechanical support and physical cues to guide cell behavior. Herein, we developed a robust methodology to increase the stiffness of polyethylene glycol (PEG) hydrogels by successfully incorporating carbon nanotubes (CNTs) within the polymer matrix. Interestingly, hydrogels containing pristine CNTs showed a higher stiffness (1915 ±â€¯102 Pa) than both hydrogels without CNTs (1197 ±â€¯125 Pa) and hydrogels incorporating PEG-grafted CNTs (867 ±â€¯103 Pa) (p < 0.005). The swelling ratio was lower for hydrogels with pristine CNTs (45.4 ±â€¯3.5) and hydrogels without CNTs (46.7 ±â€¯5.1) compared to the hydrogels with PEG-grafted CNTs (62.8 ±â€¯2.6). To confirm that the CNT-reinforced hydrogels were cytocompatible, the viability, proliferation, and morphology of encapsulated L929 fibroblasts was investigated. All hydrogel formulations supported cell proliferation, and the addition of pristine CNTs increased initial cell viability (83.3 ±â€¯10.7%) compared to both pure PEG hydrogels (51.9 ±â€¯8.3%) and hydrogels with PEG-CNTs (63.1 ±â€¯10.9%) (p < 0.005). Altogether, these results demonstrate that incorporation of CNTs could effectively reinforce PEG hydrogels and that the resulting cytocompatible nanocomposites are promising scaffolds for tissue engineering.

Gelatin microspheres releasing transforming growth factor drive in vitro chondrogenesis of human periosteum derived cells in micromass culture.

For cartilage tissue engineering, several in vitro culture methodologies have displayed potential for the chondrogenic differentiation of mesenchymal stem cells (MSCs). Micromasses, cell aggregates or pellets, and cell sheets are all structures with high cell density that provides for abundant cell-cell interactions, which have been demonstrated to be important for chondrogenesis. Recently, these culture systems have been improved via the incorporation of growth factor releasing components such as degradable microspheres within the structures, further enhancing chondrogenesis. Herein, we incorporated different amounts of gelatin microspheres releasing transforming growth factor ß1 (TGF-ß1) into micromasses composed of human periosteum derived cells (hPDCs), an MSC-like cell population. The aim of this research was to investigate chondrogenic stimulation by TGF-ß1 delivery from these degradable microspheres in comparison to exogenous supplementation with TGF-ß1 in the culture medium. Microscopy showed that the gelatin microspheres could be successfully incorporated within hPDC micromasses without interfering with the formation of the structure, while biochemical analysis and histology demonstrated increasing DNA content at week 2 and accumulation of glycosaminoglycan and collagen at weeks 2 and 4. Importantly, similar chondrogenesis was achieved when TGF-ß1 was delivered from the microspheres compared to controls with TGF-ß1 in the medium. Increasing the amount of growth factor within the micromasses by increasing the amount of microspheres added did not further improve chondrogenesis of the hPDCs. These findings demonstrate the potential of using cytokine releasing, gelatin microspheres to enhance the chondrogenic capabilities of hPDC micromasses as an alternative to supplementation of the culture medium with growth factors. STATEMENT OF SIGNIFICANCE: Gelatin microspheres are utilized for growth factor delivery to enhance chondrogenesis of mesenchymal stem cells (MSCs) in high cell density culture systems. Herein, we employ a new combination of these microspheres with micromasses of human periosteum-derived cells, which possess ease of isolation, excellent expansion potential, and MSC-like differentiation capabilities. The resulting localized delivery of transforming growth factor ß1 increases glycosaminoglycan and collagen production within the micromasses without exogenous stimulation in the medium. This unique combination is able to drive chondrogenesis up to similar levels as seen in micromasses that do receive exogenous stimulation. The addition of growth factor releasing microspheres to high cell density micromasses has the potential to reduce costs associated with this strategy for cartilage tissue engineering.

In Vitro Screening of Molecularly Engineered Polyethylene Glycol Hydrogels for Cartilage Tissue Engineering using Periosteum-Derived and ATDC5 Cells.

The rapidly growing field of tissue engineering and regenerative medicine has brought about an increase in demand for biomaterials that mimic closely the form and function of biological tissues. Therefore, understanding the cellular response to the changes in material composition moves research one step closer to a successful tissue-engineered product. With this in mind, polyethylene glycol (PEG) hydrogels comprised of different concentrations of polymer (2.5%, 4%, 6.5%, or 8% (w/v)); different protease sensitive, peptide cross-linkers (VPMSMRGG or GPQGIWGQ); and the incorporation or lack of a peptide cell adhesion ligand (RGD) were screened for their ability to support in vitro chondrogenesis. Human periosteum-derived cells (hPDCs), a mesenchymal stem cell (MSC)-like primary cell source, and ATDC5 cells, a murine carcinoma-derived chondrogenic cell line, were encapsulated within the various hydrogels to assess the effects of the different formulations on cellular viability, proliferation, and chondrogenic differentiation while receiving exogenous growth factor stimulation via the medium. Through the results of this screening process, the 6.5% (w/v) PEG constructs, cross-linked with the GPQGIWGQ peptide and containing the RGD cell binding molecule, demonstrated an environment that consistently supported cellular viability and proliferation as well as chondrogenic differentiation.

Prevalence of Needlestick Injuries, Attitude Changes, and Prevention Practices Over 12 Years in an Urban Academic Hospital Surgery Department.

OBJECTIVE: Needlestick injury prevalence, protection practices, and attitudes were assessed. Current medical students were compared with 2003 data to assess any changes that occurred with engineered safety feature implementation. BACKGROUND: Risk of occupational exposure to bloodborne pathogens is elevated in the operating room particularly with surgeons in training and nurses. METHODS: A cross-sectional survey was distributed to medical students (n = 358) and Department of Surgery staff (n = 247). RESULTS: The survey response rate was 24.8%. Needlestick injuries were reported by 38.7% of respondents (11% high risk), and the most common cause was "careless/accidental." Needlestick injury prevalence increased from medical students to residents and fellows (100%). Thirty-three percent of injured personnel had at least one unreported injury, and the most common reason was "inconvenient/too time consuming." Needlestick injury prevalence and double-glove use in medical students did not differ from 2003, and 25% of fellows reported always wearing double gloves. The true seroconversion rate for bloodborne pathogens was underestimated or unknown. The concern for contracting a bloodborne pathogen significantly decreased (65%) compared to 2003, and there were significantly less medical students with hepatitis B vaccinations (78.3%). Level of concern for contracting a bloodborne pathogen was predictive of needlestick injury. CONCLUSIONS: Needlestick injury and occupational exposure to bloodborne pathogens are significant hazards for surgeons and nurses. Attitudes regarding risk are changing, and the true seroconversion risk is underestimated. Educational efforts focused on needlestick injury prevalence, seroconversion rates, and double-glove perforation rates may be effective in implementing protective strategies.