Artificial Constructs Research Articles

UV radiation promotes melanoma dissemination mediated by the sequential reaction axis of cathepsins\u2013TGF-\u03b21\u2013FAP-\u03b1

Background:Ultraviolet radiation (UVR) is the major risk factor for development of malignant melanoma. Fibroblast activation protein (FAP)-α is a serine protease expressed on the surface of activated fibroblasts, promoting tumour invasion through extracellular matrix (ECM) degradation. The signalling mechanism behind the upregulation of FAP-α is not yet completely revealed.Methods:Expression of FAP-α was analysed after UVR exposure in in vitro co-culture systems, gene expression arrays and artificial skin constructs. Cell migration and invasion was studied in relation to cathepsin activity and secretion of transforming growth factor (TGF)-β1.Results:Fibroblast activation protein-α expression was induced by UVR in melanocytes of human skin. The FAP-α expression was regulated by UVR-induced release of TGF-β1 and cathepsin inhibitors prevented such secretion. In melanoma cell culture models and in a xenograft tumour model of zebrafish embryos, FAP-α mediated ECM degradation and facilitated tumour cell dissemination.Conclusions:Our results provide evidence for a sequential reaction axis from UVR via cathepsins, TGF-β1 and FAP-α expression, promoting cancer cell dissemination and melanoma metastatic spread.

CRISPR/Cas9 Genome Editing Reveals That the Intron Is Not Essential for var2csa Gene Activation or Silencing in Plasmodium falciparum.

ABSTRACTPlasmodium falciparum relies on monoallelic expression of 1 of 60 var virulence genes for antigenic variation and host immune evasion. Each var gene contains a conserved intron which has been implicated in previous studies in both activation and repression of transcription via several epigenetic mechanisms, including interaction with the var promoter, production of long noncoding RNAs (lncRNAs), and localization to repressive perinuclear sites. However, functional studies have relied primarily on artificial expression constructs. Using the recently developed P. falciparum clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system, we directly deleted the var2csa P. falciparum 3D7_1200600 (Pf3D7_1200600) endogenous intron, resulting in an intronless var gene in a natural, marker-free chromosomal context. Deletion of the var2csa intron resulted in an upregulation of transcription of the var2csa gene in ring-stage parasites and subsequent expression of the PfEMP1 protein in late-stage parasites. Intron deletion did not affect the normal temporal regulation and subsequent transcriptional silencing of the var gene in trophozoites but did result in increased rates of var gene switching in some mutant clones. Transcriptional repression of the intronless var2csa gene could be achieved via long-term culture or panning with the CD36 receptor, after which reactivation was possible with chondroitin sulfate A (CSA) panning. These data suggest that the var2csa intron is not required for silencing or activation in ring-stage parasites but point to a subtle role in regulation of switching within the var gene family.

Differentiation and sarcomere formation in skeletal myocytes directly prepared from human induced pluripotent stem cells using a sphere-based culture

Human induced-pluripotent stem cells (iPSCs) are a promising resource for propagation of myogenic progenitors. Our group recently reported a unique protocol for the derivation of myogenic progenitors directly (without genetic modification) from human pluripotent cells using free-floating spherical culture. Here we expand our previous efforts and attempt to determine how differentiation duration, culture surface coatings, and nutrient supplements in the medium influence progenitor differentiation and formation of skeletal myotubes containing sarcomeric structures. A long differentiation period (over 6 weeks) promoted the differentiation of iPSC-derived myogenic progenitors and subsequent myotube formation. These iPSC-derived myotubes contained representative sarcomeric structures, consisting of organized myosin and actin filaments, and could spontaneously contract. We also found that a bioengineering approach using three-dimensional (3D) artificial muscle constructs could facilitate the formation of elongated myotubes. Lastly, we determined how culture surface coating matrices and different supplements would influence terminal differentiation. While both Matrigel and laminin coatings showed comparable effects on muscle differentiation, B27 serum-free supplement in the differentiation medium significantly enhanced myogenesis compared to horse serum. Our findings support the possibility to create an in vitro model of contractile sarcomeric myofibrils for disease modeling and drug screening to study neuromuscular diseases.

3D Mimicry of Native-Tissue-Fiber Architecture Guides Tendon-Derived Cells and Adipose Stem Cells into Artificial Tendon Constructs.

Tendon and ligament (T/L) function is intrinsically related with their unique hierarchically and anisotropically organized extracellular matrix. Their natural healing capacity is, however, limited. Here, continuous and aligned electrospun nanofiber threads (CANT) based on synthetic/natural polymer blends mechanically reinforced with cellulose nanocrystals are produced to replicate the nanoscale collagen fibrils grouped into microscale collagen fibers that compose the native T/L. CANT are then incrementally assembled into 3D hierarchical scaffolds, resulting in woven constructions, which simultaneously mimic T/L nano-to-macro architecture, nanotopography, and nonlinear biomechanical behavior. Biological performance is assessed using human-tendon-derived cells (hTDCs) and human adipose stem cells (hASCs). Scaffolds nanotopography and microstructure induce a high cytoskeleton elongation and anisotropic organization typical of tendon tissues. Moreover, the expression of tendon-related markers (Collagen types I and III, Tenascin-C, and Scleraxis) by both cell types, and the similarities observed on their expression patterns over time suggest that the developed scaffolds not only prevent the phenotypic drift of hTDCs, but also trigger tenogenic differentiation of hASCs. Overall, these results demonstrate a feasible approach for the scalable production of 3D hierarchical scaffolds that exhibit key structural and biomechanical properties, which can be advantageously explored in acellular and cellular T/L TE strategies.

Gender, media, and myth-making: constructing China’s leftover women

ABSTRACTIn the last 10 years, the term ‘leftover women’ (剩女)—educated, unmarried women over the age of 27—has emerged as a visible stereotype in popular consciousness in China. Despite the surplus of men that is a result of China’s One Child Policy, women are blamed for marriage market challenges through sexist narratives and terminology. While some scholarship treats ‘leftover women’ as an accepted demographic phenomenon with clear causes and impacts, it can also be viewed as an artificial construct created through socially generated gender stereotypes and furthered through media messaging. This article examines and compares sociological research on Chinese marriage patterns, presentations of ‘leftover women’ in contemporary Chinese media, and independent interview findings to understand the role of media in the construction of gender discourse and the perpetuation of gender stereotypes. These rigid concepts of gender roles and ideal womanhood have far-flung consequences, both for women who internalize these misperceptions and for the social hierarchies supported by antiquated gender constructs.

The PPAR-gamma-binding sequence Pal3 is necessary for basal but dispensable for high-fat diet regulated human renin expression in the kidney.

We reported earlier that PPAR-gamma regulates renin transcription through a human-specific atypical binding sequence termed hRen-Pal3. Here we developed a mouse model to investigate the functional relevance of the hRen-Pal3 sequence in vivo since it might be responsible for the increased renin production in obesity and thus for the development of accompanying arterial hypertension. We used bacterial artificial chromosome construct and co-placement strategy to generate two transgenic mouse lines expressing the human renin gene from identical genomic locus without affecting the intrinsic mouse renin expression. One line carried a wild-type hRen-Pal3 in the transgene (Pal3wt strain) and the other a mutated non-functional Pal3 (Pal3mut strain). Human renin expression was correctly targeted to the renin-producing juxtaglomerular (JG) cells of kidney in both lines. However, Pal3mut mice had lower basal human renin expression. Since human renin does not recognize mouse angiotensinogen as substrate, the blood pressure was not different between the strains. Stimulation of renin production with the angiotensin-converting enzyme inhibitor enalapril equipotentially stimulated the human renin expression in Pal3wt and Pal3mut mice. High-fat diet for 10weeks which is known to activate PPAR-gamma failed to increase human renin mRNA in kidneys of either strain. These findings showed that the human renin PPAR-gamma-binding sequence hRen-Pal3 is essential for basal renin expression but dispensable for the cell-specific and high-fat diet regulated renin expression in the kidney.

A Parvovirus B19 synthetic genome: sequence features and functional competence

Central to genetic studies for Parvovirus B19 (B19V) is the availability of genomic clones that may possess functional competence and ability to generate infectious virus. In our study, we established a new model genetic system for Parvovirus B19. A synthetic approach was followed, by design of a reference genome sequence, by generation of a corresponding artificial construct and its molecular cloning in a complete and functional form, and by setup of an efficient strategy to generate infectious virus, via transfection in UT7/EpoS1 cells and amplification in erythroid progenitor cells. The synthetic genome was able to generate virus with biological properties paralleling those of native virus, its infectious activity being dependent on the preservation of self-complementarity and sequence heterogeneity within the terminal regions. A virus of defined genome sequence, obtained from controlled cell culture conditions, can constitute a reference tool for investigation of the structural and functional characteristics of the virus.

Quality Improvement in Neurology: Dementia Management Quality Measurement Set Update.

Dementia is a neurologic condition manifested by a substantial decline in multiple cognitive abilities that collectively render a person unable to function at expected levels and progressively impede independent ability to perform everyday activities. For decades, public health officials have warned of the coming tsunami of Alzheimer disease (AD), and dementia has even been characterized as the dominant scourge of modern times, replacing cancer.1 Recently, hopeful signs have appeared, including reports from some longitudinal research studies that incidence of dementia is declining,2 and from the federal government that research funding for AD and other dementias will approach $1 billion USD in 2017.3 The authors thank all the Dementia Management Update Quality Measurement Set Work Group members for their dedication, time, energy, contributions and work that supported the development of this manuscript: Amy E. Sanders, MD, MS, FAAN (American Academy of Neurology); Robert Roca, MD (American Psychiatric Association); Piero Antuono, MD (American Academy of Neurology); Kelly Sullivan, PhD (American Academy of Neurology); Karl Goodkin, MD, PhD, DFAPA (American Psychiatric Association); Donovan Maust, MD, MS (American Psychiatric Association); Michael Lubin, MD, MACP (American College of Physicians); Sam Fazio, PhD (Alzheimer's Association); Ann Knutson (Alzheimer's Association); Robert O'Keefe, MA (Alzheimer's Association); Eric Tangalos, MD, FACP, AGSF, CMD (AMDA–The Society for Post-Acute and Long-Term Care Medicine); Glenn Smith, PhD (American Academy of Clinical Neuropsychology and American Psychological Association); Brian Unwin, MD, FAAFP (American Academy of Family Physicians); Joseph Shega, MD (American Academy of Hospice and Palliative Medicine); Dale Strasser, MD (American Academy of Physical Medicine and Rehabilitation); Michele Grigaitis, DNP, FNP-BC, CNRN (American Association of Neuroscience Nurses); Jerry Johnson, MD (American Geriatric Society); Mary Kathleen Owens, RN MSN, C-NE, RAC-CT (American Health Care Association and Gerontological Advanced Practice Nurses Association); Catherine Piersol, PhD, OTR, FAOTA (American Occupational Therapy Association); Lise McCarthy, PT, DPT, GCS (American Physical Therapy Association); Kathleen Welsh-Bohmer, PhD, ABPP (American Psychological Association); David Webster, MD, MBA (Humana); James Galvin, MD, MPH, FANA (Lewy Body Dementia Association); Daniel Marson, PhD, JD (National Academy of Neuropsychology); Richard Fortinsky, PhD (The Gerontological Society of America); Marsden McGuire, MD (Veteran's Affairs); John Absher, MD (American Academy of Neurology Facilitator); James Nininger, MD (American Psychiatric Association Facilitator); Amy Bennett, JD (American Academy of Neurology Staff); Gina Gjorvad (American Academy of Neurology Staff); Erin Hagen (American Academy of Neurology Staff); Becky Schierman, MPH (American Academy of Neurology Staff); Samantha Shugarman, MS (American Psychiatric Association Staff); and Kristin Kroeger (American Psychiatric Association Staff). The authors also thank Jean O'Keefe for participation and the individuals and organizations who offered public comments.

Genome-Wide Abolishment of Mobile Genetic Elements Using Genome Shuffling and CRISPR/Cas-Assisted MAGE Allows the Efficient Stabilization of a Bacterial Chassis.

The ideal bacterial chassis provides a simplified, stable and predictable host environment for synthetic biological circuits. Mutability and evolution can, however, compromise stability, leading to deterioration of artificial genetic constructs. By eliminating certain sources of instability, these undesired genetic changes can be mitigated. Specifically, deletion of prophages and insertion sequences, nonessential constituents of bacterial genomes, has been shown to be beneficial in cellular and genetic stabilization. Here, we sought to establish a rapid methodology to improve the stability of microbial hosts. The novel workflow involves genome shuffling between a mobile genetic element-free strain and the target cell, and subsequent rounds of CRISPR/Cas-assisted MAGE on multiplex targets. The power and speed of the procedure was demonstrated on E.coli BL21(DE3), a host routinely used for plasmid-based heterologous protein expression. All 9 prophages and 50 insertion elements were efficiently deleted or inactivated. Together with additional targeted manipulations (e.g., inactivation of error-prone DNA-polymerases), the changes resulted in an improved bacterial host with a hybrid (harboring segments of K-12 DNA), 9%-downsized and clean genome. The combined capacity of phage-mediated generalized transduction and CRISPR/Cas-selected MAGE offers a way for rapid, large scale editing of bacterial genomes.

Minimally Invasive Anterior Cervical Discectomy Without Fusion to Treat Cervical Disc Herniations in Patients with Previous Cervical Fusions.

Adjacent level cervical disc disease and secondarily progressive disc space degeneration that develops years after previously successful anterior cervical fusion at one or more levels is a common, but potentially complex problem to manage. The patient is faced with the option of further open surgery which involves adding another level of disc removal with fusion, posterior decompression, and stabilization, or possibly replacing the degenerated disc with an artificial disc construct. These three cases demonstrate that some patients, especially after minor trauma, may have small herniated discs as the cause for their new symptoms rather than progressive segmental degeneration. Each patient became symptomatic after minor trauma three to six years after the original fusion and had no or minimal radiologic changes of narrowing of the disc or spur formation commonly seen in adjacent level disease, but rather had magnetic resonance imaging (MRI) findings typical of small herniated discs. After failing multiple months of conservative treatment they were offered surgery as an option. Subsequently, all three were successfully treated with minimal anterior discectomy without fusion. There are no reports in the literature of using minimal anterior cervical discectomy without fusion in previous fused patients. This report reviews the background of adjacent level cervical disease, the various biomechanical explanations for developing a new disc herniation rather than progressive segmental degeneration, and how anterior cervical discectomy without fusion can be an option in these patients.

Kilobase Pair Chromatin Fiber Contacts Promoted by Living-System-Like DNA Linker Length Distributions and Nucleosome Depletion.

Nucleosome placement, or DNA linker length patterns, are believed to yield specific spatial features in chromatin fibers, but details are unknown. Here we examine by mesoscale modeling how kilobase (kb) range contacts and fiber looping depend on linker lengths ranging from 18 to 45 bp, with values modeled after living systems, including nucleosome free regions (NFRs) and gene encoding segments. We also compare artificial constructs with alternating versus randomly distributed linker lengths in the range of 18-72 bp. We show that nonuniform distributions with NFRs enhance flexibility and encourage kb-range contacts. NFRs between neighboring gene segments diminish short-range contacts between flanking nucleosomes, while enhancing kb-range contacts via hierarchical looping. We also demonstrate that variances in linker lengths enhance such contacts. In particular, moderate sized variations in fiber linker lengths (∼27 bp) encourage long-range contacts in randomly distributed linker length fibers. Our work underscores the importance of linker length patterns, alongside bound proteins, in biological regulation. Contacts formed by kb-range chromatin folding are crucial to gene activity. Because we find that special linker length distributions in living systems promote kb contacts, our work suggests ways to manipulate these patterns for regulation of gene activity.

Laurence Monnais and Harold J. Cook, eds. Global Movements, Local Concerns: Medicine and Health in Southeast Asia. Singapore: NUS Press, 2012, xxxi+290p.

Global Movements, Local Concerns: Medicine and Health in Laurence Monnais and Harold J. Cook, eds. Singapore: NUS Press, 2012, xxxi+290p.This edited volume contributes to the growing scholarly literature dealing with the history of The editors collaborated with 12 scholars of to come up with an 11-chapter compilation dealing with six countries, Indonesia, Malaysia, the Philippines, Singapore, Thailand, and Vietnam. This is difficult task to perform, as most scholarship tends to focus on one South- east Asian country or comparison between countries with similar histories, given that charac- teristic of Asian countries is their diversity.The volume begins by deconstructing the prevalent notion that the term Southeast Asia was constructed by North American scholars and its allies during the Second World War as way to group the countries into a community of nation-states. Asia, to quote Benedict Anderson, is an artificial construct and the region is remote, heterogeneous, and . . . imperially segmented (Anderson 1998, 5). Another strategy has been to group these countries according to the influences of the region's powerful neighbors, China and India. However, this proved to be insufficient with the migration of Arab, Chinese, and Indians to various countries fostering an image of plural societies. It was only with the introduction of the Braudelian view of long duree- researching one topic over an extended period of time and analyzing material culture in the context of global history-that framework for studying as whole became possible.1)The editors of the volume make clear that the chapters deal with issues of health rather than disease in the countries involved. The chapters avoid dealing with medicine, and focus on the development of medicine. Hence, instead of colonial masters imposing their policies upon the locals, the chapters examine the negotiations between colonial masters and locals and the appropriation of medical practices and policies within local context.This is welcome compilation for Asian scholars and those who study the history of medicine due to its ambition in attempting to tell the history of using micro- level narratives and social histories. However, one of the main issues that arise out of any compi- lation on the history of is the difficulty in grappling with the diversity that exists in region. This difficulty makes itself felt in the compilation and can be seen in the confusing order of the chapters from what initially seems to be chronological (chapters 1 to 8) to an abrupt transi- tion to the modern period with chapter 9, and then back to chronological order with chapters 10 and 11.Thomas B. Colvin's study deals with the expedition of Francisco Xavier Balmis, doctor to the Spanish court who proposed to bring the smallpox vaccine to all of Spain's colonies. The Balmis expedition brought the vaccine using the human chain method, which meant transporting number of healthy young boys who had not been exposed to smallpox and transferring the vaccine from one boy to another until they arrived at the final destination. The Spanish monarchy approved the expedition in order to increase the population of the colonies that had been afflicted by smallpox and stimulate economic activity in the colonies. Despite encountering problems not only with the locals, but with the Spanish as well, the expedition was successful and would have further influence within the surrounding countries.C. Michele Thompson narrates how the Nguyen Dynasty addressed the problem of smallpox and how officials transported the vaccine to Vietnam from France. The smallpox vaccination project was long-term policy; however, the methods in transporting the vaccine introduced by the French proved to be unsuccessful, since it was brought via glass vials, which failed to preserve the live virus on its journey through the summer heat of the South China Sea. …

FUS affects circular RNA expression in murine embryonic stem cell-derived motor neurons

The RNA-binding protein FUS participates in several RNA biosynthetic processes and has been linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Here we report that FUS controls back-splicing reactions leading to circular RNA (circRNA) production. We identified circRNAs expressed in in vitro-derived mouse motor neurons (MNs) and determined that the production of a considerable number of these circRNAs is regulated by FUS. Using RNAi and overexpression of wild-type and ALS-associated FUS mutants, we directly correlate the modulation of circRNA biogenesis with alteration of FUS nuclear levels and with putative toxic gain of function activities. We also demonstrate that FUS regulates circRNA biogenesis by binding the introns flanking the back-splicing junctions and that this control can be reproduced with artificial constructs. Most circRNAs are conserved in humans and specific ones are deregulated in human-induced pluripotent stem cell-derived MNs carrying the FUSP525L mutation associated with ALS.

Rescue of recombinant Newcastle disease virus: a short history of how it all started.

Reverse genetics of viruses has come a long way, and many recombinant viruses have been generated since the first successful "rescues" were reported in the late 1970s. Recombinant Newcastle disease virus (rNDV), a non-segmented negative-sense RNA virus (NSNSV), was first rescued in 1999 using a reverse genetics approach similar to that reported for other recombinant viruses of the order Mononegavirales a few years before. The route from an original NDV isolate to the generation of its recombinant counterpart requires many steps that have to be sequentially and carefully completed. Background knowledge of each of these steps is essential because it allows one to make the best choices for fulfilling the specific requirements of the final recombinant virus. We have previously reviewed the latest strategies in cloning the NDV full-length cDNA into transcription vectors and the use of different RNA polymerase systems for the generation of viral RNA from plasmid DNA. In this article, we review a number of discoveries on the mechanism of transcription and replication of NDV, including a brief history behind the discovery of its RNP complex. This includes the generation of artificial and functional RNP constructs, in combination with the smart use of available knowledge and technologies that ultimately resulted in rescue of the first rNDV.

Anti-proliferative and anti-migratory effects of hyperforin in 2D and 3D artificial constructs of human dermal fibroblasts – A new option for hypertrophic scar treatment?

Hyperforin (HYP), one of the main bioactive compounds in extracts of Hypericum perforatum, is a potential drug candidate for the treatment of skin diseases. Since extracts have proven to support wound healing, in the present study effects of HYP on human dermal fibroblasts (HDF) were evaluated in 2D and 3D in vitro dermal constructs. Viability and cytotoxicity assays as well as a live-dead cell staining were performed to test at which concentration HYP reduces viability and/or shows cytotoxicity. Furthermore a differentiation between cytotoxic, anti-proliferative and anti-migratory effects was done. For the latter purpose a 2D migration assay was performed. HDF-induced contraction of a 3D artificial dermal (AD) construct was determined at given HYP concentration. Induction of apoptosis was examined by determination of caspase 3/7 activities. HYP reduced viability of HDF down to 70% at concentrations of 5–10µM. This decrease was not due to cytotoxicity but to a reduction in proliferation as shown from both the proliferation assay and the cytotoxicity assay as well as from live-dead cell staining. The 2D migration assay showed that HYP reduced migration activity of HDF cells at a concentration of 10µM. At this concentration HYP also reduced the HDF-induced contraction of collagen gels as 3D AD constructs. Apoptotic effects of HYP were excluded performing a caspase 3/7 activity detecting assay. The results show for the first time that HYP may be rather a potential candidate for treatment of hypertrophic scars than promoting effects which are understood as important in wound healing.

Artificial microRNAs and synthetic trans-acting small interfering RNAs interfere with viroid infection.

SummaryArtificial microRNAs (amiRNAs) and synthetic trans‐acting small interfering RNAs (syn‐tasiRNAs) are two classes of artificial small RNAs (sRNAs) engineered to silence endogenous transcripts as well as viral RNAs in plants. Here, we explore the possibility of using amiRNAs and syn‐tasiRNAs to specifically interfere with infections by viroids, small (250–400‐nucleotide) non‐coding circular RNAs with compact secondary structure infecting a wide range of plant species. The combined use of recent high‐throughput methods for artificial sRNA construct generation and the Potato spindle tuber viroid (PSTVd)–Nicotiana benthamiana pathosystem allowed for the simple and time‐effective screening of multiple artificial sRNAs targeting sites distributed along PSTVd RNAs of (+) or (–) polarity. The majority of amiRNAs were highly active in agroinfiltrated leaves when co‐expressed with an infectious PSTVd transcript, as were syn‐tasiRNAs derived from a construct including the five most effective amiRNA sequences. A comparative analysis showed that the effects of the most effective amiRNA and of the syn‐tasiRNAs were similar in agroinfiltrated leaves, as well as in upper non‐agroinfiltrated leaves in which PSTVd accumulation was significantly delayed. These results suggest that amiRNAs and syn‐tasiRNAs can be used effectively to control viroid infections in plants.

Mimicking Natural Photosynthsis: Ultrafast Charge Transfer in PpcA Ru(bpy)3 Complexes

Converting light energy into its electrochemical equivalent requires precise control and fine tuning of relevant kinetic and thermodynamic parameters, including primary charge separation. To this end, we developed a series of 22 cysteine mutants of PpcA, a 3-heme cytochrome from Geobacter sulfurreducens as a model system to study short distance photo-induced electron transfer. These proteins were successfully expressed in E.coli and isolated for covalent labeling with Ru(bpy)2(bpy-Br). Protein purity and successful posttranslational modifications were confirmed with HPLC-MS. Time-resolved nanosecond and ultrafast transient absorbance characterization was performed at Argonne National Laboratory (ANL) and identified 6 constructs with apparent photo-induced charge transfer time constants of 20 ps or faster, including 2 constructs with 1-2 ps time constants. The latter is a significant result as up to this point only natural photosynthetic systems demonstrated such a fast initial charge separation, while all artificial covalent constructs exhibited charge transfer rates 3 or more orders of magnitude slower. To understand molecular principles responsible for such a dramatic acceleration of electron transfer rates, we conducted small- and wide angle X-ray scattering data collection at the Advanced Photon Source at ANL. Further, we are currently attempting to obtain X-ray crystallographic and NMR structures of the ultrafast constructs. Finally, we performed triplicate 250-300 ns all-atom molecular dynamics simulations of all 6 ultrafast constructs. Based on the obtained results we conclude that that photo-induced ultrafast charge transfer requires van der Waals contact between heme vinyl groups and photosensitizers while contacts with propionates or short covalent donor-acceptor distances play a much less significant role.

Bioprinting and Biofabrication with Peptide and Protein Biomaterials.

The ability to fabricate artificial tissue constructs through the controlled organisation of cells, structures and signals within a biomimetic scaffold offers significant promise to the field of regenerative medicine, drug delivery and tissue engineering. Advances in additive manufacturing technologies have facilitated the printing of spatially defined cell-laden artificial tissue constructs capable of providing biomimetic spatiotemporal presentation of biological and physical cues to cells in a designed multicomponent structure. Despite significant progress in the field of bioprinting, a key challenge remains in developing and utilizing materials that can adequately recapitulate the complexities of the native extracellular matrix on a nanostructured, chemical level during the printing process. This gives rise to the need for suitable materials - particularly in establishing effective control over cell fate, tissue vascularization and innervation. Recently, significant interested has been invested into developing candidate materials using protein and peptide-derived biomaterials. The ability of these materials to form highly printable hydrogels which are reminiscent of the native ECM has seen significant use in a variety of regenative applications, including both organ bioprinting and non-organ bioprinting. Here, we discuss the emerging technologies for peptide-based bioprinting applications, highlighting bioink development and detailing bioprinter processors. Furthermore, this work presents application specific, peptide-based bioprinting approaches, and provides insight into current limitations and future perspectives of peptide-based bioprinting techniques.

Polyhydroxyalkanoates as biomaterials.

Polyhydroxyalkanoates (PHAs) are biopolymers synthesized by bacteria under unbalanced growth conditions. These biopolymers are considered as potential biomaterials for future applications because they are biocompatible, biodegradable, and easy to produce and functionalize with strong mechanical strength. Currently, PHAs are being extensively innovated for biomedical applications due to their prerequisite properties. The wide range of biomedical applications includes drug delivery systems, implants, tissue engineering, scaffolds, artificial organ constructs, etc. In this article we review the utility of PHAs in various forms (bulk/nano) for biomedical applications so as to bring about the future vision for PHAs as biomaterials for the advancement of research and technology.

The inverse hockey stick effect: an empirical investigation of the fiscal calendar’s impact on firm inventories

We empirically investigate how manufacturers’ inventory decisions relate to the fiscal calendar. Although optimal firm inventories should depend on demand and supply, we find that the artificial accounting construct of the fiscal year frequently drives inventory dynamics. In an effort to manage earnings and cash flows (CFs) towards the fiscal year-end (FYE), firms significantly reduce their inventories in the fourth fiscal quarter only to increase their inventories in the next fiscal year. Using a sample of 4877 US manufacturing firms for the period 1990–2010, we find that inventories are 3.9–6.0% lower on average in the fourth fiscal quarter. In the analysis, we control for inventory theory-related factors that have been identified in prior literature. Because this pattern is the inverse of that observed for sales, we refer to this phenomenon as the inverse hockey stick effect. The effect holds for all three individual inventory types: raw materials, work in progress and finished goods. We find that inventory reductions in the fourth fiscal quarter are particularly substantial if firms have an incentive to beat CF targets. In contrast to our expectations, we do not find evidence that financial distress links to inventory reductions at the FYE.