Protein-modified biomaterials can be used to modulate cellular function in three dimensions. However, as the dynamic heterogeneous control over complex cell physiology continues to be sought, ...strategies that permit a reversible and user-defined tethering of fragile proteins to materials remain in great need. Here we introduce a modular and robust semisynthetic approach to reversibly pattern cell-laden hydrogels with site-specifically modified proteins. Exploiting a versatile sortase-mediated transpeptidation, we generate a diverse library of homogeneous, singly functionalized proteins with bioorthogonal reactive handles for biomaterial modification. We demonstrate the photoreversible immobilization of fluorescent proteins, enzymes and growth factors to gels with excellent spatiotemporal resolution while retaining native protein bioactivity. Localized epidermal growth factor presentation enables dynamic regulation over proliferation, intracellular mitogen-activated protein kinase signalling and subcellularly resolved receptor endocytosis. Our method broadly permits the modification and patterning of a wide range of proteins, which provides newfound avenues to probe and direct advanced cellular fates in four dimensions.
In light of the existing preliminary evidence of a link between Covid-19 and poor air quality, which is largely based upon correlations, we estimate the relationship between long term air pollution ...exposure and Covid-19 in 355 municipalities in the Netherlands. Using detailed data we find compelling evidence of a positive relationship between air pollution, and particularly
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concentrations, and Covid-19 cases, hospital admissions and deaths. This relationship persists even after controlling for a wide range of explanatory variables. Our results indicate that, other things being equal, a municipality with 1 μg/m
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concentrations will have 9.4 more Covid-19 cases, 3.0 more hospital admissions, and 2.3 more deaths. This relationship between Covid-19 and air pollution withstands a number of sensitivity and robustness exercises including instrumenting pollution to mitigate potential endogeneity in the measurement of pollution and modelling spatial spillovers using spatial econometric techniques.
Light is a uniquely powerful tool for controlling molecular events in biology. No other external input (e.g., heat, ultrasound, magnetic field) can be so tightly focused or so highly regulated as a ...clinical laser. Drug delivery vehicles that can be photonically activated have been developed across many platforms, from the simplest “caging” of therapeutics in a prodrug form, to more complex micelles and circulating liposomes that improve drug uptake and efficacy, to large-scale hydrogel platforms that can be used to protect and deliver macromolecular agents including full-length proteins. In this Review, we discuss recent innovations in photosensitive drug delivery and highlight future opportunities to engineer and exploit such light-responsive technologies in the clinical setting.
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Although biochemically patterned hydrogels are capable of recapitulating many critical aspects of the heterogeneous cellular niche, exercising spatial and temporal control of the presentation and ...removal of biomolecular signalling cues in such systems has proved difficult. Here, we demonstrate a synthetic strategy that exploits two bioorthogonal photochemistries to achieve reversible immobilization of bioactive full-length proteins with good spatial and temporal control within synthetic, cell-laden biomimetic scaffolds. A photodeprotection-oxime-ligation sequence permits user-defined quantities of proteins to be anchored within distinct subvolumes of a three-dimensional matrix, and an ortho-nitrobenzyl ester photoscission reaction facilitates subsequent protein removal. By using this approach to pattern the presentation of the extracellular matrix protein vitronectin, we accomplished reversible differentiation of human mesenchymal stem cells to osteoblasts in a spatially defined manner. Our protein-patterning approach should provide further avenues to probe and direct changes in cell physiology in response to dynamic biochemical signalling.
This paper examines the extent to which the EKC inverted U relationship can be explained by trade and specifically the migration or displacement of ‘dirty’ industries from the developed regions to ...the developing regions (the pollution haven hypothesis (PHH)). Using detailed data on North–South trade flows for pollution intensive products the evidence for the PHH is assessed. Emissions of 10 air and water pollutants are then estimated, controlling for trade openness, structural change and ‘dirty’ North–South trade flows. Evidence of pollution haven effects is found, although such effects do not appear to be widespread and appear to be relatively small compared to the roles played other explanatory variables.
Despite clear evidence that manifest variable path analysis requires highly reliable measures, path analyses with fallible measures are commonplace even in premier journals. Using fallible measures ...in path analysis can cause several serious problems: (a) As measurement error pervades a given data set, many path coefficients may be either over- or underestimated. (b) Extensive measurement error diminishes power and can prevent invalid models from being rejected. (c) Even a little measurement error can cause valid models to appear invalid. (d) Differential measurement error in various parts of a model can change the substantive conclusions that derive from path analysis. (e) All of these problems become increasingly serious and intractable as models become more complex. Methods to prevent and correct these problems are reviewed. The conclusion is that researchers should use more reliable measures (or correct for measurement error in the measures they do use), obtain multiple measures for use in latent variable modeling, and test simpler models containing fewer variables.
Hydrogel biomaterials derived from natural biopolymers (e.g., fibrin, collagen, decellularized extracellular matrix) are regularly utilized in three-dimensional (3D) cell culture and tissue ...engineering. In contrast to those based on synthetic polymers, natural materials permit enhanced cytocompatibility, matrix remodeling, and biological integration. Despite these advantages, natural protein-based gels have lagged behind synthetic alternatives in their tunability; methods to selectively modulate the biochemical properties of these networks in a user-defined and heterogeneous fashion that can drive encapsulated cell function have not yet been established. Here, we report a generalizable strategy utilizing a photomediated oxime ligation to covalently decorate naturally derived hydrogels with bioactive proteins including growth factors. This bioorthogonal photofunctionalization is readily amenable to mask-based and laser-scanning lithographic patterning, enabling full four-dimensional (4D) control over protein immobilization within virtually any natural protein-based biomaterial. Such versatility affords exciting opportunities to probe and direct advanced cell fates inaccessible using purely synthetic approaches in response to anisotropic environmental signaling.
Platelet rich plasma (PRP) was tested as a potential therapy for androgenetic alopecia (AGA) through two different clinical protocols in which one population (18 participants) received half-head ...treatment with autologous non-activated PRP (A-PRP) produced by CPunT Preparation System (Biomed Device, Modena, Italy) and the other half-head with placebo, and a second separated population in which all participants (n = 6, 3 participants per group) received treatment with calcium-activated PRP (AA-PRP) produced from one of two different PRP collection devices (Regen Blood Cell Therapy or Arthrex Angel System). For the A-PRP study, three treatments were administered over 30-day intervals. Trichoscan analysis of patients, three months post-treatment, showed a clinical improvement in the number of hairs in the target area (36 ± 3 hairs) and in total hair density (65± 5 hair cm2), whereas negligible improvements in hair count (1.1± 1.4 hairs) and density (1.9 ± 10.2 hair cm2) were seen in the region of the scalp that received placebo. Microscopic evaluation conducted two weeks after treatment showed also an increase in epidermal thickness, Ki67+ keratinocytes, and in the number of follicles. The AA-PRP treatment groups received a singular set of injections, and six months after the treatments were administered, notable differences in clinical outcomes were obtained from the two PRP collection devices (+90 ± 6 hair cm2 versus -73 ± 30 hair cm2 hair densities, Regen versus Arthrex). Growth factor concentrations in AA-PRP prepared from the two collection devices did not differ significantly upon calcium activation.
There has been enormous growth in faculty-led short-term study abroad programs because they offer flexibility and expand opportunities for students and faculty members who wish to study and work ...abroad but do not have the resources or time to spend a semester or year away. These experiential programs offer unique opportunities for university faculty to teach their disciplines abroad while engaging students in direct, authentic cultural encounters for transformative change.This volume provides a detailed framework and guidance on how to plan and implement a faculty-led study abroad program. Seasoned faculty leaders and administrators describe an overall program development process, comprehensively identify the elements for designing the curriculum, and offer advice and solutions to unique challenges inherent in various types of programs. The contributors cover the logistics for managing program details at home and abroad provide advice on writing a university proposal, creating a budget, the marketing and recruitment of students, handling abroad logistics, and preparing students for the abroad experience all illustrated by examples drawn from their experiences. Most importantly, readers will come to understand the difference between experiences that are more touristic than scholarly and gain guidance on designing or redesigning their own programs to ensure academically sound, culturally-relevant curricula that complements the international field site.The opening section sets the scene by describing the overall process of designing and delivering faculty-led abroad programs, from conception to implementation. The core of the book is grounded in evidence-based research for designing international curricula and syllabi, and includes five case studies illustrating short term programs focused on interdisciplinary subject matter, field study, global service learning, internship immersion, and language and cultural study. This practical guide concludes with faculty activities critical to a programs success: marketing and recruiting students; preparing teaching events for before, during, and after the abroad experience; and formulating a plan to leave a small footprint abroad. This book constitutes a handbook for college and university professors who plan to or already conduct short-term study abroad programs as well as administrators and staff of global and international programs.
Click chemistry provides extremely selective and orthogonal reactions that proceed with high efficiency and under a variety of mild conditions, the most common example being the copper(I)-catalysed ...reaction of azides with alkynes. While the versatility of click reactions has been broadly exploited, a major limitation is the intrinsic toxicity of the synthetic schemes and the inability to translate these approaches into biological applications. This manuscript introduces a robust synthetic strategy where macromolecular precursors react through a copper-free click chemistry, allowing for the direct encapsulation of cells within click hydrogels for the first time. Subsequently, an orthogonal thiol-ene photocoupling chemistry is introduced that enables patterning of biological functionalities within the gel in real time and with micrometre-scale resolution. This material system enables us to tailor independently the biophysical and biochemical properties of the cell culture microenvironments in situ. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gels with ideal structures that can be photopatterned, and all in the presence of cells.
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