Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2–Containing Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form

Pixelated: A Second Childhood

Senior Project submitted to The Division of Languages and Literature of Bard College

Device for non-disruptive taking of melt samples from a compounding process and direct injection molding

A concept for taking a sample from a polymer melt stream plus the direct processing of this melt to specimen is presented. Therefore, a melt sampling and direct injection molding (MSIM) device was developed. Process parameters were studied and the set-up was implemented successfully. Using the MSIM device, different thermoplastics were processed and provided specimen characterized. The mechanical material properties from samples of the MSIM process show a good consistency compared with data from conventional processes. The MSIM device can be used in production processes for quality control, e.g. color or mechanical properties, as well as in the field of research and development to reduce development cycles

Superabsorbent polymer additives for repeated barrier restoration of damaged powder coatings under wet-dry cycles: A proof-of-concept

Superabsorbent polymers (SAPs) are well known for their ability to absorb and hold high water amounts accompanied by a high volume expansion. In this work we show the benefits of this underlying property of SAPs to induce underwater crack closure with subsequent barrier restoration in damaged protective coatings. For the proof of concept, three layer epoxy-polyester (EP) powder coating systems were developed and applied on carbon steel. In these systems the middle EP layer (also called functional layer) contained crosslinked acrylamide/acrylic acid copolymer SAPs in different amounts ranging from 0 to 40 wt%. The capability of the SAPs to close damages and extend barrier and corrosion protection was evaluated by electrochemical impedance spectroscopy (EIS), NaCl aqueous solution immersion test and optical microscopy. It was found that coatings loaded with a 20 wt% SAP led to the best overall corrosion protection for the studied systems. In order to proof the potential use of this extrinsic healing concept for multiple healing events wet-dry cycles on scratched systems were performed and the corrosion performance was followed by EIS. Although not yet optimal, the results show the potential of the concept for multiple healing events under wet-dry conditions.Novel Aerospace Material

Genetic, Cellular, and Molecular Heterogeneity in Adrenals With Aldosterone-Producing Adenoma

International audienceAldosterone-producing adenoma (APA) cause primary aldosteronism—the most frequent form of secondary hypertension. Somatic mutations in genes coding for ion channels and ATPases are found in APA and in aldosterone-producing cell clusters. We investigated the genetic, cellular, and molecular heterogeneity of different aldosterone-producing structures in adrenals with APA, to get insight into the mechanisms driving their development and to investigate their clinical and biochemical correlates. Genetic analysis of APA, aldosterone-producing cell clusters, and secondary nodules was performed in adrenal tissues from 49 patients by next-generation sequencing following CYP11B2 immunohistochemistry. Results were correlated with clinical and biochemical characteristics of patients, steroid profiles, and histological features of the tumor and adjacent adrenal cortex. Somatic mutations were identified in 93.75% of APAs. Adenoma carrying KCNJ5 mutations had more clear cells and cells expressing CYP11B1, and fewer cells expressing CYP11B2 or activated β-catenin, compared with other mutational groups. 18-hydroxycortisol and 18-oxocortisol were higher in patients carrying KCNJ5 mutations and correlated with histological features of adenoma; however, mutational status could not be predicted using steroid profiling. Heterogeneous CYP11B2 expression in KCNJ5 -mutated adenoma was not associated with genetic heterogeneity. Different mutations were identified in secondary nodules expressing aldosterone synthase and in independent aldosterone-producing cell clusters from adrenals with adenoma; known KCNJ5 mutations were identified in 5 aldosterone-producing cell clusters. Genetic heterogeneity in different aldosterone-producing structures in the same adrenal suggests complex mechanisms underlying APA development

Framework for scenario development in LCA

This article is based on the work of the SETAC-Europe LCA Working Group ‘Scenario Development in LCA’, which has started its work in April 1998. The goal of the Working Group is to focus on the use of scenarios in Life Cycle Assessment (LCA). This article presents the results of the first phase of the Working Group. The previous definitions of scenarios include three common basic elements: the definition of alternative future circumstances, the path from the present to the future, and the inclusion of uncertainty in the concept. We define a scenario in LCA as ”a description of a possible future situation relevant for specific LCA applications, based on specific assumptions about the future, and (when relevant) also including the presentation of the development from the present to the future.” On the basis of the scenario definition we distinguish between two basic approaches for scenari

Negative regulation of CD8 expression via Cd8 enhancer–mediated recruitment of the zinc finger protein MAZR

Coreceptor expression is tightly regulated during thymocyte development. Deletion of specific Cd8 enhancers leads to variegated expression of CD8αβ heterodimers in double-positive (DP) thymocytes. Here we show CD8 variegation was correlated with an epigenetic “off” state, linking Cd8 enhancer function with chromatin remodeling of the adjacent genes Cd8a and Cd8b1 (Cd8). We show the zinc finger protein MAZR, encoded by the Zfp278 gene, bound the Cd8 enhancer and interacted with the corepressor N-CoR complex in double-negative thymocytes. MAZR was down-regulated in DP and single-positive CD8(+) thymocytes. Enforced expression of MAZR led to impaired Cd8 activation and variegated CD8 expression. Our results demonstrate epigenetic control of the Cd8 gene loci and identify MAZR as an important regulator of Cd8 gene expression