Tissue engineering and regenerative medicine is an exciting research area that aims at regenerative alternatives to harvested tissues for transplantation. Biomaterials play a pivotal role as ...scaffolds to provide three-dimensional templates and synthetic extracellular matrix environments for tissue regeneration. It is often beneficial for the scaffolds to mimic certain advantageous characteristics of the natural extracellular matrix, or developmental or wound healing programs. This article reviews current biomimetic materials approaches in tissue engineering. These include synthesis to achieve certain compositions or properties similar to those of the extracellular matrix, novel processing technologies to achieve structural features mimicking the extracellular matrix on various levels, approaches to emulate cell–extracellular matrix interactions, and biologic delivery strategies to recapitulate a signaling cascade or developmental/wound healing program. The article also provides examples of enhanced cellular/tissue functions and regenerative outcomes, demonstrating the excitement and significance of the biomimetic materials for tissue engineering and regeneration.
Concern over dwindling water supplies for urban areas as well as environmental degradation from existing urban water systems has motivated research into more resilient and sustainable water supply ...strategies. Greywater reuse has been suggested as a way to diversify local water supply portfolios while at the same time lessening the burden on existing environments and infrastructure. Constructed wetlands have been proposed as an economically and energetically efficient unit process to treat greywater for reuse purposes, though their ability to consistently meet applicable water quality standards, microbiological in particular, is questionable. We therefore review the existing case study literature to summarize the treatment performance of greywater wetlands in the context of chemical, physical and microbiological water quality standards. Based on a cross-section of different types of wetlands, including surface flow, subsurface flow, vertical and recirculating vertical flow, across a range of operating conditions, we show that although microbiological standards cannot reliably be met, given either sufficient retention time or active recirculation, chemical and physical standards can. We then review existing case study literature for typical water supply disinfection unit processes including chlorination, ozonation and ultraviolet radiation treating either raw or treated greywater specifically. An evaluation of effluent water quality from published wetland case studies and the expected performance from disinfection processes shows that under appropriate conditions these two unit processes together can likely produce effluent of sufficient quality to meet all nonpotable reuse standards. Specifically, we suggest that recycling vertical flow wetlands combined with ultraviolet radiation disinfection and chlorine residual is the best combination to reliably meet the standards.
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•Constructed wetlands are a low energy treatment process with potential to adequately treat greywater for nonpotable reuse•Greywater contaminant removals are complex and reductions vary depending on the contaminant and operating conditions•With right disinfection measures, constructed wetlands may be a safe, low energy option for decentralized, nonpotable reuse
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder caused by the loss of motor neurons from the brain and spinal cord. The ALS community has made remarkable strides over three ...decades by identifying novel familial mutations, generating animal models, elucidating molecular mechanisms, and ultimately developing promising new therapeutic approaches. Some of these approaches reduce the expression of mutant genes and are in human clinical trials, highlighting the need to carefully consider the normal functions of these genes and potential contribution of gene loss-of-function to ALS. Here, we highlight known loss-of-function mechanisms underlying ALS, potential consequences of lowering levels of gene products, and the need to consider both gain and loss of function to develop safe and effective therapeutic strategies.
In this review, Kim et al. discuss evidence for loss-of-function mutations and mechanisms in amyotrophic lateral sclerosis (ALS) and propose the need to consider both gain and loss of function for designing effective and safe therapeutic strategies.
Self‐healing supramolecular hydrogels have emerged as a novel class of biomaterials that combine hydrogels with supramolecular chemistry to develop highly functional biomaterials with advantages ...including native tissue mimicry, biocompatibility, and injectability. These properties are endowed by the reversibly cross‐linked polymer network of the hydrogel. These hydrogels have great potential for realizing yet to be clinically translated tissue engineering therapies. This review presents methods of self‐healing supramolecular hydrogel formation and their uses in tissue engineering as well as future perspectives.
Self‐healing supramolecular hydrogels are a novel class of biomaterials that offer unique advantages in tissue engineering. This review describes important methods of supramolecular hydrogel formation as well as recent advances and emerging applications of these hydrogels in regenerative medicine.
Summary Objective Knee osteoarthritis (KOA) is a common disease that is characterized by the degeneration of joint cartilage in the knee. Genetic factors have been implicated in KOA. Recently, ...several genetic studies have suggested that susceptibility to KOA is affected by the number of aspartic acid (D) residues in the amino-terminal of the asporin protein, but evidence remains conflicting. Therefore, the objective of the present meta-analysis was to investigate whether or not the D-repeat polymorphism is associated with susceptibility to KOA. Methods A systematic search of all relevant studies published through Dec 2012 was conducted using the MEDLINE, EMBASE, OVID, and ScienceDirect. Allelic counts were evaluated for the D14 and D13 alleles respectively. The included studies were only assessed in the analysis of the following allele model: D14 allele vs others alleles combined, D13 allele vs others alleles combined, and D14 allele vs D13 allele. Results Seven studies (eight comparisons) with 5515 total participants (2334 KOA patients and 3181 controls), which involved four Caucasian and four Asian populations, were eligible for inclusion. Meta-analysis was conducted for genotype D14 vs others combined, D13 vs others combined, and D14 vs D13. In the stratification based on ethnicity, studies were divided into Caucasian and Asian populations. We did not detect positive association between KOA and the D14 allele in Asian populations (OR = 1.527, 95% CI: 0.879–2.653) and in Caucasian populations (OR = 1.053, 95% CI: 0.905–1.225). There was also no positive association between susceptibility to KOA and D13 allele in Asian populations (OR = 0.950, 95% CI: 0.732–1.233) and in Caucasian populations (OR = 0.866, 95% CI: 0.723–1.037). Conclusion The present results suggest that the D-repeat of asporin gene (ASPN) may not be a major susceptibility locus in the Caucasian and Asian populations with KOA. Because of the limitations of the present meta-analysis, accurate conclusions could not be drawn based on the current evidence, and further studies with large sample size are required.
Abstract The development of three-dimensional (3D) biomimetic scaffolds which provide an optimal environment for cells adhesion, proliferation and differentiation, and guide new tissue formation has ...been one of the major goals in tissue engineering. In this work, a processing technique has been developed to create 3D nanofibrous gelatin (NF-gelatin) scaffolds, which mimic both the physical architecture and the chemical composition of natural collagen. Gelatin matrices with nanofibrous architecture were first created by using a thermally induced phase separation (TIPS) technique. Macroporous NF-gelatin scaffolds were fabricated by combining the TIPS technique with a porogen-leaching process. The processing parameters were systematically investigated in relation to the fiber diameter, fiber length, surface area, porosity, pore size, interpore connectivity, pore wall architecture, and mechanical properties of the NF-gelatin scaffolds. The resulting NF-gelatin scaffolds possess high surface areas (>32 m2 /g), high porosities (>96%), well-connected macropores, and nanofibrous pore wall structures. The technique advantageously controls macropore shape and size by paraffin spheres, interpore connectivity by assembly conditions (time and temperature of heat treatment), pore wall morphology by phase separation and post-treatment parameters, and mechanical properties by polymer concentration and crosslinking density. Compared to commercial gelatin foam (Gelfoam® ), the NF-gelatin scaffold showed much better dimensional stability in a tissue culture environment. The NF-gelatin scaffolds, therefore, are excellent scaffolds for tissue engineering.
Abstract
In antiferromagnets, the efficient transport of spin-waves has until now only been observed in the insulating antiferromagnet hematite, where circularly (or a superposition of pairs of ...linearly) polarized spin-waves diffuse over long distances. Here, we report long-distance spin-transport in the antiferromagnetic orthoferrite YFeO
3
, where a different transport mechanism is enabled by the combined presence of the Dzyaloshinskii-Moriya interaction and externally applied fields. The magnon decay length is shown to exceed hundreds of nanometers, in line with resonance measurements that highlight the low magnetic damping. We observe a strong anisotropy in the magnon decay lengths that we can attribute to the role of the magnon group velocity in the transport of spin-waves in antiferromagnets. This unique mode of transport identified in YFeO
3
opens up the possibility of a large and technologically relevant class of materials, i.e., canted antiferromagnets, for long-distance spin transport.
Abstract Bone tissue engineering is a highly interdisciplinary field that seeks to tackle the most challenging bone-related clinical issues. The major components of bone tissue engineering are the ...scaffold, cells, and growth factors. This review will focus on the scaffold and recent advancements in developing scaffolds that can mimic the natural extracellular matrix of bone. Specifically, these novel scaffolds mirror the nanofibrous collagen network that comprises the majority of the non-mineral portion of bone matrix. Using two main fabrication techniques, electrospinning and thermally-induced phase separation, and incorporating bone-like minerals, such as hydroxyapatite, composite nanofibrous scaffolds can improve cell adhesion, stem cell differentiation, and tissue formation. This review will cover the two main processing techniques and how they are being applied to fabricate scaffolds for bone tissue engineering. It will then cover how these scaffolds can enhance the osteogenic capabilities of a variety of cell types and survey the ability of the constructs to support the growth of clinically relevant bone tissue.
Biomaterials with injectability, conductivity and antibacterial effect simultaneously have been rarely reported. Herein, we developed a new series of in situ forming antibacterial conductive ...degradable hydrogels using quaternized chitosan (QCS) grafted polyaniline with oxidized dextran as crosslinker. The chemical structures, morphologies, electrochemical property, conductivity, swelling ratio, rheological property, in vitro biodegradation and gelation time of hydrogels were characterized. Injectability was verified by in vivo subcutaneous injection on a Sprague Dawley rat. The antibacterial activity of the hydrogels was firstly evaluated employing antibacterial assay using Escherichia coli and Staphylococcus aureus in vitro. The hydrogels containing polyaniline showed enhanced antibacterial activity compared to QCS hydrogel, especially for hydrogels with 3 wt% polyaniline showing 95 kill% and 90kill% for E. coli and S. aureus, respectively. Compared with QCS hydrogel, the hydrogels with 3 wt% polyaniline still showed enhanced antibacterial activity for E. coli in vivo. The adipose-derived mesenchymal stem cells (ADMSCs) were used to evaluate the cytotoxicity of the hydrogels and hydrogels with polyaniline showed better cytocompatibility than QCS hydrogel. The electroactive hydrogels could significantly enhance the proliferation of C2C12 myoblasts compared to QCS hydrogel. This work opens the way to fabricate in situ forming antibacterial and electroactive degradable hydrogels as a new class of bioactive scaffolds for tissue regeneration applications.
Summary
Benzodiazepines (BZDs) are some of the most commonly prescribed drugs in the world. It has been shown that BZD use could be associated with increased fracture risk. However, studies on the ...use of BZDs and fracture risk have yielded inconsistent results. Results from the present meta-analysis show that BZD use is associated with a moderate and clinically significant increase in the risk of fractures.
Introduction
The relationship between the use of BZDs and fracture risk has been neither well identified nor summarized. This meta-analysis reports on the use of BZDs, especially short-acting BZDs, and their correlation with a moderate and clinically significant increase in fracture risk. This analysis will provide evidence for clinicians to consider fracture risk when prescribing BZDs among the elderly population. This study was conducted to determine whether people who take BZDs are at an increased fracture risk.
Methods
A systematic search of studies published through January 2013 was conducted using MEDLINE, EMBASE, OVID, and ScienceDirect. Case–control and cohort studies that assessed the relationship between BZD use and the risk of fractures were identified. Literature searches, study selections, methodological assessments, and data mining were independently conducted by two reviewers. Disagreements were resolved by consensus. STATA 12.0 software was used for the meta-analysis. Random effects models were used for pooled analysis due to heterogeneity among the studies.
Results
There were 25 studies, including 19 case–control studies and 6 cohort studies, that met the inclusion criteria. Overall, the results of the meta-analysis indicated that BZD use was associated with a significantly increased fracture risk (relative risk (RR) = 1.25; 95 % confidence intervals (CI), 1.17–1.34;
p
< 0.001). Increased fracture risk associated with BZD use was observed in participants aged ≥65 years old (RR = 1.26; 95 % CI, 1.15–1.38;
p
< 0.001). When only hip fractures were included as the outcome measure, the RR increased to 1.35. However, subgroup meta-analyses showed that there was no significant association between BZD use and fracture risk in Eastern countries (RR = 1.27; 95 % CI, 0.76–2.14;
p
= 0.362) as well as between long-acting BZD use and risk of fractures (RR = 1.21; 95 % CI, 0.95–1.54;
p
= 0.12). After accounting for publication bias, we observed that the overall association between BZD use and fracture risk to be slightly weaker (RR = 1.21; 95 % CI, 1.13–1.30) but still significant.
Conclusion
The results of this meta-analysis demonstrate that the use of BZD, especially short-acting BZD, is associated with a moderate and clinically significant increase in fracture risk. However, large prospective studies that minimize selection bias are necessary to determine a more accurate fracture risk associated with BZD use.
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