A scaffold containing zinc oxide for Schwann cell-mediated axon growth

Objective.Schwann cells (SCs) transplanted in damaged nervous tissue promote axon growth, which may support the recovery of function lost after injury. However, SC transplant-mediated axon growth is often limited and lacks direction.Approach.We have developed a zinc oxide (ZnO) containing fibrous scaffold consisting of aligned fibers of polycaprolactone (PCL) with embedded ZnO nanoparticles as a biodegradable, bifunctional scaffold for promoting and guiding axon growth. This scaffold has bifunctional properties wherein zinc is released providing bioactivity and ZnO has well-known piezoelectric properties where piezoelectric materials generate electrical activity in response to minute deformations. In this study, SC growth, SC-mediated axon extension, and the presence of myelin basic protein (MBP), as an indicator of myelination, were evaluated on the scaffolds containing varying concentrations of ZnOin vitro. SCs and dorsal root ganglion (DRG) neurons were cultured, either alone or in co-culture, on the scaffolds.Main results.Findings demonstrated that scaffolds with 1 wt.% ZnO promoted the greatest SC growth and SC-mediated axon extension. The presence of brain-derived neurotrophic factor (BDNF) was also determined. BDNF increased in co-cultures for all scaffolds as compared to SCs or DRGs cultured alone on all scaffolds. For co-cultures, cells on scaffolds with low levels of ZnO (0.5 wt.% ZnO) had the highest amount of BDNF as compared to cells on higher ZnO-containing scaffolds (1 and 2 wt.%). MBP immunostaining was only detected in co-cultures on PCL control scaffolds (without ZnO).Significance.The results of this study demonstrate the potential of the ZnO-containing scaffolds for SC-mediated axon growth and its potential for use in nervous tissue repair.

POS1148 RISK FACTORS FOR POLYARTICULAR GOUT FLARES—ANALYSIS OF A LONGITUDINAL ONLINE GOUT FOLLOW-UP STUDY

Background:

There are known and established risk factors for gout flares; however, no study has examined the factors specifically associated with a polyarticular gout flare.

Objectives:

Evaluate risk factors of a polyarticular gout flare in a longitudinal study of individuals with gout.

Methods:

We used data from the Boston Online Gout Study, a longitudinal internet-based case-crossover study, where gout patients with at least one flare within the past year were enrolled across the US. Participants (N=903) were followed prospectively for 1 year via the internet to collect information on gout flares and related data including number and specific joints involved, medical comorbidities, diet, exercise and medications.

A polyarticular gout flare was defined as having 3 or more joints involved during a patient-reported flare period. Individuals with at least one flare (to determine flare pattern) during follow-up were included in the analysis. Univariable associations were first assessed to determine factors were associated with polyarticular joint flares. was used to adjust for confounders. When assessing the association of each risk factor with prevalent polyarticular joint involvement, we used multivariable logistic regression, adjusting specific confounders guided by causal diagram.

Results:

There were 724 participants with at least one flare with a mean and median age of 55 years. The cohort was 78% male and 89% White with a mean gout disease duration of 8.1 years (median 5). 197 (27%) had a polyarticular gout flare. In univariable analysis (Table 1), female sex, osteoarthritis, obesity, heart failure, hypertension, chronic kidney disease and gout related medication use were each associated with higher odds of polyarticular gout flare, whereas higher education, alcohol use at study enrollment and aspirin use were associated with lower odds. In multivariable analysis, obesity, osteoarthritis and heart failure remained associated with a higher odds of polyarticular gout flare, whereas education remained inversely associated.

Conclusion:

In this prospective cohort of gout patients, obesity, heart failure and osteoarthritis were independently associated with higher odds for polyarticular gout flares. Female sex was also positively associated, whereas higher education was protective. The positive association with gout-related medications likely reflects residual confounding by indication. If confirmed, these findings would help identify those at risk for polyarticular flares to help improve clinical care.

Table 1.

Associations with Polyarticular Gout Flare (≥ 3 joints)

Risk FactorUnivariable OR (95% CI)Age- and Sex-Adjusted OR (95% CI)Multivariable OR* (95% CI)Age ≥ 55 years (vs < 55)0.82 (0.59,1.14)0.77 (0.56,1.08)0.70 (0.49,1.01)Female Sex1.51 (1.04,2.22)1.55 (1.03,2.32)1.21 (0.78,1.88)White Race (vs Non-White)0.89 (0.54,1.48)0.93 (0.56,1.54)0.75 (0.44,1.28)Education (vs High School or Less)Some college0.63 (0.37,1.07)0.53 (0.37,1.07)0.68 (0.39,1.17)College0.45 (0.25,0.78)0.46 (0.26,0.81)0.49 (0.27,0.88)Post-graduate0.42 (0.25,0.72)0.44 (0.26,0.76)0.48 (0.28,0.84)Body Mass Index (kg/m2) at Enrollment (vs < 25)25-29.91.69 (0.85,3.33)1.77 (0.89,3.51)1.82 (0.90,3.65)≥ 302.38 (1.24,4.58)2.30 (1.19,4.43)2.19 (1.12,4.28)Alcohol Use at Enrollment (vs. Non-Use)0.60 (0.40,0.89)0.60 (0.40,0.91)**Gout Duration ≥ 5 years (vs < 5)0.85 (0.61,1.18)0.93 (0.66,1.31)0.95 (0.66,1.35)Presence of Comorbidities at Enrollment (vs Absence)Osteoarthritis2.35 (1.45,3.81)2.37 (1.43,3.95)2.39 (1.42,4.04)Heart Failure2.06 (1.11,3.81)2.21 (1.17,4.17)2.03 (1.06,3.91)Hypertension1.61 (1.08,2.40)1.69 (1.10,2.60)**Chronic Kidney Disease1.97 (1.03,3.78)2.11 (1.09,4.11)**Medication Use at Enrollment (vs No Use)Allopurinol1.58 (1.13,2.22)1.59 (1.13,2.23)**Diuretics1.53 (1.06,2.21)1.59 (1.06,2.38)**Oral Steroids2.21 (1.16,4.18)2.26 (1.19,4.31)**Aspirin0.68 (0.47,0.98)0.72 (0.49,1.07)**

*Mutually adjusted for the variables in this column

**Not included in model

Acknowledgements:

NIH P50AR060772.

Disclosure of Interests:

Jonathan Dau: None declared, Natalie McCormick: None declared, Sarah Stratton: None declared, Chio Yokose: None declared, Clara Chen: None declared, Tuhina Neogi Shareholder of: Lilly, EMD Merck Serono, Novartis, Regeneron, Pfizer/Lilly, David Hunter Shareholder of: Pfizer, Lilly, Merck Serono, Kenneth Saag Consultant of: Arthrosi, Horizon Therapeutics plc, Atom Bioscience, LG Pharma, Takeda, Mallinkrodt, SOBI, Grant/research support from: Horizon Therapeutics plc, Shanton, SOBI, Yuqing Zhang: None declared, Hyon Choi Consultant of: Ironwood, Selecta, Horizon, Takeda, Kowa, Vaxart, Grant/research support from: Ironwood, Horizon.

The Effect of Physical Cues of Biomaterial Scaffolds on Stem Cell Behavior

Stem cells have been sought as a promising cell source in the tissue engineering field due to their proliferative capacity as well as differentiation potential. Biomaterials have been utilized to facilitate the delivery of stem cells in order to improve their engraftment and long-term viability upon implantation. Biomaterials also have been developed as scaffolds to promote stem cell induced tissue regeneration. This review focuses on the latter where the biomaterial scaffold is designed to provide physical cues to stem cells in order to promote their behavior for tissue formation. Recent work that explores the effect of scaffold physical properties, topography, mechanical properties and electrical properties, is discussed. Although still being elucidated, the biological mechanisms, including cell shape, focal adhesion distribution, and nuclear shape, are presented. This review also discusses emerging areas and challenges in clinical translation.

Polymeric ionically conductive composite matrices and electrical stimulation strategies for nerve regeneration: In vitro characterization

Stem cell strategies and the use of electrical stimulation (ES) represent promising new frontiers for peripheral nerve regeneration. Composite matrices were fabricated by coating electrospun polycaprolactone/cellulose acetate micro-nanofibers with chitosan and ionically conductive (IC) polymers including, sulfonated polyaniline, and lignin sulfonate. These composite matrices were characterized for surface morphology, coating uniformity, ionic conductivity, and mechanical strength to explore as scaffold materials for nerve regeneration in conjunction with ES. Composite matrices measured conductivity in the range of 0.0049-0.0068 mS/m due to the uniform coating of sulfonated polymers on the micro-nanofibers. Thin films (2D) and composite fiber matrices (3D) of IC polymers seeded with human mesenchymal stem cells (hMSCs) were electrically stimulated at 0.5 V, 20 Hz for 1 h daily for 14 days to study the changes in cell viability, morphology, and expression of the neuronal-like phenotype. In vitro ES lead to changes in hMSCs' fibroblast morphology into elongated neurite-like structures with cell bodies for ES-treated and positive control growth factor-treated groups. Immunofluorescent staining revealed the presence of neuronal markers including β3-tubulin, microtubule-associated protein 2, and nestin in response to ES. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1792-1805, 2019.

Polymeric 3D Printed Structures for Soft-Tissue Engineering

3D printing, or rapid prototyping, is a fabrication technique that is used for various engineering applications with advantages such as mass production and fine tuning of spatial-dimensional properties. Recently, this fabrication method has been adopted for tissue engineering applications due to its ability to finely tune porosity and create precise, uniform, and repeatable structures. This review aims to introduce 3D printing applications in soft tissue engineering and regenerative medicine including state-of-the-art scaffolds and key future challenges. Furthermore, 3D printing of individual cells, an evolution of traditional 3D printing technology which represents a cutting-edge technique for the creation of cell seeded scaffolds in vitro, is discussed. Key advances demonstrate the advantages of 3D printing, while also highlighting potential shortcomings to improve upon. It is clear that as 3D printing technology continues to develop, it will serve as a truly revolutionary means for fabrication of structures and materials for regenerative applications.

Bioactive polymeric scaffolds for tissue engineering

A variety of engineered scaffolds have been created for tissue engineering using polymers, ceramics and their composites. Biomimicry has been adopted for majority of the three-dimensional (3D) scaffold design both in terms of physicochemical properties, as well as bioactivity for superior tissue regeneration. Scaffolds fabricated via salt leaching, particle sintering, hydrogels and lithography have been successful in promoting cell growth in vitro and tissue regeneration in vivo. Scaffold systems derived from decellularization of whole organs or tissues has been popular due to their assured biocompatibility and bioactivity. Traditional scaffold fabrication techniques often failed to create intricate structures with greater resolution, not reproducible and involved multiple steps. The 3D printing technology overcome several limitations of the traditional techniques and made it easier to adopt several thermoplastics and hydrogels to create micro-nanostructured scaffolds and devices for tissue engineering and drug delivery. This review highlights scaffold fabrication methodologies with a focus on optimizing scaffold performance through the matrix pores, bioactivity and degradation rate to enable tissue regeneration. Review highlights few examples of bioactive scaffold mediated nerve, muscle, tendon/ligament and bone regeneration. Regardless of the efforts required for optimization, a shift in 3D scaffold uses from the laboratory into everyday life is expected in the near future as some of the methods discussed in this review become more streamlined.

Association between prescription co-payment amount and compliance with adjuvant hormonal therapy in women with early-stage breast cancer

PURPOSE

Noncompliance with adjuvant hormonal therapy among women with breast cancer is common. Little is known about the impact of financial factors, such as co-payments, on noncompliance.

PATIENTS AND METHODS

We conducted a retrospective cohort study by using the pharmacy and medical claims database at Medco Health Solutions. Women older than age 50 years who were taking aromatase inhibitors (AIs) for resected breast cancer with two or more mail-order prescriptions, from January 1, 2007, to December 31, 2008, were identified. Patients who were eligible for Medicare were analyzed separately. Nonpersistence was defined as a prescription supply gap of more than 45 days without subsequent refill. Nonadherence was defined as a medication possession ratio less than 80% of eligible days.

RESULTS

Of 8110 women younger than age 65 years, 1721 (21.1%) were nonpersistent and 863 (10.6%) were nonadherent. Among 14,050 women age 65 years or older, 3476 (24.7%) were nonpersistent and 1248 (8.9%) were nonadherent. In a multivariate analysis, nonpersistence (ever/never) in both age groups was associated with older age, having a non-oncologist write the prescription, and having a higher number of other prescriptions. Compared with a co-payment of less than $30, a co-payment of $30 to $89.99 for a 90-day prescription was associated with less persistence in women age 65 years or older (odds ratio [OR], 0.69; 95% CI, 0.62 to 0.75) but not among women younger than age 65, although a co-payment of more than $90 was associated with less persistence both in women younger than age 65 (OR, 0.82; 95% CI, 0.72 to 0.94) and those age 65 years or older (OR, 0.72; 95% CI, 0.65 to 0.80). Similar results were seen with nonadherence.

CONCLUSION

We found that higher prescription co-payments were associated with both nonpersistence and nonadherence to AIs. This relationship was stronger in older women. Because noncompliance is associated with worse outcomes, future policy efforts should be directed toward interventions that would help patients with financial difficulties obtain life-saving medications.

Indications of proton-dominated cosmic-ray composition above 1.6 EeV

We report studies of ultrahigh-energy cosmic-ray composition via analysis of depth of air shower maximum (X(max)), for air shower events collected by the High-Resolution Fly's Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d<X(max)>/d[log(E)] of 47.9+/-6.0(stat)+/-3.2(syst) g/cm2/decade for energies between 1.6 and 63 EeV, and are consistent with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which the galactic-to-extragalactic transition is the cause of the energy spectrum ankle at 4x10(18) eV.

Basis for avid homologous DNA strand exchange by human Rad51 and RPA

Human Rad51 (hRad51), a member of a conserved family of general recombinases, is shown here to have an avid capability to make DNA joints between homologous DNA molecules and promote highly efficient DNA strand exchange of the paired molecules over at least 5.4 kilobase pairs. Furthermore, maximal efficiency of homologous DNA pairing and strand exchange is strongly dependent on the heterotrimeric single-stranded DNA binding factor hRPA and requires conditions that lessen interactions of the homologous duplex with the hRad51-single-stranded DNA nucleoprotein filament. The homologous DNA pairing and strand exchange system described should be valuable for dissecting the action mechanism of hRad51 and for deciphering its functional interactions with other recombination factors.

Superhelicity-driven homologous DNA pairing by yeast recombination factors Rad51 and Rad54

Yeast Rad51 recombinase has only minimal ability to form D loop. Addition of Rad54 renders D loop formation by Rad51 efficient, even when topologically relaxed DNA is used as substrate. Treatment of the nucleoprotein complex of Rad54 and relaxed DNA with topoisomerases reveals dynamic DNA remodeling to generate unconstrained negative and positive supercoils. DNA remodeling requires ATP hydrolysis by Rad54 and is stimulated by Rad51-DNA nucleoprotein complex. A marked sensitivity of DNA undergoing remodeling to P1 nuclease indicates that the negative supercoils produced lead to transient DNA strand separation. Thus, a specific interaction of Rad54 with the Rad51-ssDNA complex enhances the ability of the former to remodel DNA and allows the latter to harvest the negative supercoils generated for DNA joint formation.

The primary care of elder mistreatment

Images

Catalysis of homologous DNA pairing by yeast Rad51 and Rad54 proteins

The Saccharomyces cerevisiae RAD51 and RAD54 genes are both required for the occurrence of homologous recombination and for the repair of double-stranded DNA breaks. Previous studies have indicated that Rad51 protein, together with the single-stranded DNA-binding factor replication protein A (RPA), can promote the formation of heteroduplex DNA, which is a key intermediate in homologous recombination. Here we report the purification of the Rad54 protein to near homogeneity and the biochemical testing of its molecular function. We find that Rad54 protein possesses a double-stranded DNA-dependent ATPase activity, and that it interacts with the Rad51 protein. Addition of Rad54 protein to reactions containing Rad51 strongly stimulates the rate of pairing between homologous single-stranded and double-stranded DNA molecules. We conclude that Rad54 acts to overcome kinetic impediments that would limit homologous DNA pairing between recombining chromosomes in vivo.

Effects of adding links to "the chain of survival" for prehospital cardiac arrest: a contrast in outcomes in 1975 and 1995 at a single institution

STUDY OBJECTIVE

The concept of a "chain of survival" to improve outcome from prehospital cardiac arrest has been defined and promulgated over the last two decades. The purpose of this study was to compare outcomes of prehospital cardiac arrest in 1975 and 1995 at a single institution.

METHODS

This longitudinal, before-after study compares published data collected at our municipal, tertiary care in 1974-1975 with data collected prospectively in 1995. The 1975 study group served as control subjects (n = 120). We enrolled an equal number of consecutive patients who met inclusion criteria in the 1995 cohort (consecutive patients who experienced prehospital arrest and who received prehospital Advanced Cardiac Life Support (ACLS) measures during the two study periods). Patients younger than 18 years or with posttraumatic arrest were excluded. Between 1975 and 1995 the following "links" in the "chain of survival" were added to the prehospital care system: (1) 911 access and dispatch, (2) paramedic endotracheal intubation, (3) EMT automated defibrillation, (4) standing out-of-hospital orders before hospital radiotelemetry contact, and (5) introduction of American Heart Association ACLS algorithms.

RESULTS

The following significant differences (chi 2) were observed between the study periods: prevalence of ventricular fibrillation or tachycardia (42% in 1975 versus 28% in 1995, P = .021), prevalence of asystole or pulseless electrical activity as the first documented rhythm (58% versus 72%, P = .021), survival to hospital discharge (22% versus 9%, P = .007), and percent of survivors of ventricular fibrillation or tachycardia (30% versus 0%, P = .004). Eighty-six percent of the 1995 cohort had advanced chronic disease and 29% experienced cardiopulmonary arrest in a nursing home.

CONCLUSION

Survival decreased dramatically during the 20-year study period. This may be because of the high incidence of chronic disease, the greater frequency of asystole and pulseless electrical activity, and the inclusion of patients with "end-of-life" arrests in which ACLS protocol was initiated in the 1995 cohort. The patient population in which ACLS is initiated is the weakest link in the "chain of survival."