Reversibly crosslinked self‐healing PCL‐based networks

Poly(ε‐caprolactone) (PCL)‐based thermoreversible networks with self‐healing properties were prepared through Diels–Alder (DA) and retro‐DA reactions. Bis‐ or Tris‐maleimide compounds and a series of copolymer(caprolactone‐diene) PCL_XF_Y (X: degree of polymerization and Y: furan‐average functionality) with Y between 2.4 and 4.9 were used. The successive sequences of formation and dissociation of polycaprolactone networks via DA and retro‐DA reactions were observed repeatedly by dynamic mechanical analyses (DMA) and their gel‐temperatures determined. The cross‐linking densities, thermal properties, and thermal reversibility of the PCL_XF_Y/multimaleimide polymers have been modulated by the structure and functionalities of the used diene and dienophile moieties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Impact of ethanol content on the scavenging activities of oak wood C‐glycosidic ellagitannins. Application to the evaluation of the nutritional status of spirits

As a consequence of their structure, ellagitannins have a high level of activity in terms of their oxidative properties. In particular, their scavenging activity is often presented as a noteworthy parameter, since polyphenols have a beneficial impact on human health. A large variety of spirits, brandies and whiskeys are aged in barrels or receive a wood extract rich in polyphenols. Although spirits (alcoholic beverages) represent a very dynamic market with significant growth, very few scientific papers have been published on this topic, or have justified specific research in this field. Firstly, the scavenging properties of ellagitannins when measured in a solution are presented. An oak wood extract was fractionated by gel chromatography to obtain different fractions with different polymeric levels. It is particularly clear that the oligomer forms are the most efficient by comparison with low‐weight and high‐weight fractions. A mixture of ellagitannins has a higher scavenging intensity than the pure molecule; this illustrates the synergic effect of polyphenols. The scavenging activity of different commercial spirits depends on the presence and quantities of ellagitannins. As an example, the percentage of scavenged superoxide anion radicals represents 70 and 18%, respectively, for spirits aged in a barrel (12 years) and white spirits. In a second step, details of the influence of ethanol on the antioxidant properties of ellagitannins are provided. In particular, alcohol increases the scavenging activity of ellagitannins from 0 to 25% vol., and higher concentrations present a certain degree of pro‐oxidant activity. The chemical study of ellagitannin scavenging properties in solution is confirmed by means of a specific in vitro investigation on the DNA extracted from cells, and directly on the cells. Copyright © 2013 The Institute of Brewing & Distilling     

Short communication: A comparison of 2 nonsteroidal antiinflammatory drugs following the first stage of a 2-stage fistulation surgery in dry dairy cows

Postoperative pain and its management following fistulation surgery in cattle are poorly understood. The purpose of this study was to compare 2 nonsteroidal antiinflammatory drugs (NSAID) as potential postoperative pain management treatments following the first stage of a 2-stage fistulation surgery. A randomized complete block design trial was conducted in dry Holstein cows (n = 10) following fistulation surgery. Ketoprofen (3 mg/kg of body weight i.m.) was administered on the day of surgery and 24 h later, whereas meloxicam (0.5 mg/kg of body weight s.c.) was administered once only on the day of surgery. Outcomes evaluated at 0, 2, 9, 24, 26, and 33 h postsurgery were heart rate, respiration rate, rectal temperature, and infrared temperature around the surgical site. Outcomes evaluated on the day of surgery and d 1 following surgery and compared with the average for the 4 d before surgery were lying activity (total lying time, total time spent lying on the left side, and percentage of time lying on the left side) and feed intake. A difference was observed in dry matter intake on d 1 but this effect was not different on d 0 compared with presurgical averages. A difference was observed in time spent lying on the left side and a difference was observed in heart rate following the first stage of fistulation surgery compared with presurgical averages. The infrared temperature readings around the surgical site were significantly greater in the hours following surgery compared with presurgical averages. The respiration rate increased over time after 24 h postsurgery compared with presurgical values. Although it was clear that the surgery is painful, the drug effects were more difficult to explain. On d 0 and 1, the meloxicam-treated cows ate 3 kg more but spent 101 min/d less time lying on their left side compared with ketoprofen-treated cows. The first stage of a 2-stage fistulation surgery was considered painful based on changes in heart rate, respiration rate, infrared temperature readings, dry matter intake, and time spent lying on the left side. It is clear that left flank surgery is painful and that NSAID can improve outcomes associated with that pain, but we cannot make recommendations as to which NSAID to choose based on these results.     

Benefits in the Macrophage Response Due to Graphene Oxide Reduction by Thermal Treatment

Graphene and its derivatives are very promising nanomaterials for biomedical applications and are proving to be very useful for the preparation of scaffolds for tissue repair. The response of immune cells to these graphene-based materials (GBM) appears to be critical in promoting regeneration, thus, the study of this response is essential before they are used to prepare any type of scaffold. Another relevant factor is the variability of the GBM surface chemistry, namely the type and quantity of oxygen functional groups, which may have an important effect on cell behavior. The response of RAW-264.7 macrophages to graphene oxide (GO) and two types of reduced GO, rGO15 and rGO30, obtained after vacuum-assisted thermal treatment of 15 and 30 min, respectively, was evaluated by analyzing the uptake of these nanostructures, the intracellular content of reactive oxygen species, and specific markers of the proinflammatory M1 phenotype, such as CD80 expression and secretion of inflammatory cytokines TNF-α and IL-6. Our results demonstrate that GO reduction resulted in a decrease of both oxidative stress and proinflammatory cytokine secretion, significantly improving its biocompatibility and potential for the preparation of 3D scaffolds able of triggering the appropriate immune response for tissue regeneration.     

Synthesis and in Vitro Characterisation of Ifenprodil‐Based Fluorescein Conjugates as GluN1/GluN2B N‐Methyl‐D‐aspartate Receptor Antagonists

GluN2B‐containing NMDA receptors are involved in many important physiological functions and play a pivotal role in mediating pain as well as in several neurodegenerative disorders. We aimed to develop fluorescent probes to target the GluN2B subunit selectively in order to allow better understanding of the relationships between receptor localisation and physiological importance. Ifenprodil, known as the GluNR2B antagonist of reference, was chosen as the template for the elaboration of probes. We had previously reported a fluorescein conjugate that was shown (by confocal microscopy imaging of DS‐red‐labelled cortical neurons) to bind specifically to GluN2B. To elaborate this probe, we explored the influence of both the nature and the attachment point of the spacer between the fluorophore and the parent compound, ifenprodil. We performed chemical modifications of ifenprodil at the benzylic position and on the phenol ring by introducing secondary amine or amide functions and evaluated alkyl chains from two to 20 bonds either including or not including secondary amide functions as spacers. The previously developed probe was found to display the greatest activity in the inhibition of NMDA‐induced Ca²⁺ influx by calcium imaging experiments on HEK293 cells transfected with the cDNA encoding for GluN1‐1A and GluN2B. Further investigations revealed that this probe had a neuroprotective effect equivalent to that of ifenprodil in a standard test for neurotoxicity. Despite effects of lesser amplitude with these probes relative to ifenprodil, we demonstrated that they displaced [³H]ifenprodil in mouse brain slices in a similar manner.     

Functionalization of single- and multi-walled carbon nanotubes with cationic amphiphiles for plasmid DNA complexation and transfection

The possibility of delivering DNA efficiently to cells represents a crucial issue for the treatment of both genetic and acquired diseases. However, even although the efficiency of non-viral transfection systems has improved in the last decade, none have yet proven to be sufficiently effective in vivo. We report herein our results on the functionalization of single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) by two cationic amphiphiles (lipid RPR120535 and pyrenyl polyamine), their use for the complexation of plasmid DNA, and their efficiency in transfecting cells in vitro. The experiments have shown that the efficiency of transfection is higher when using SWNT instead of MWNT, and that transfection efficiency is similar or slightly higher when using nanoplexes (SWNT/lipid RPR120535/DNA) instead of lipoplexes (lipid RPR120535/DNA) and several orders of magnitude higher than that of naked DNA. This study therefore shows both that the transfection is better when using SWNTs and that it is dependent on the nature of the amphiphilic molecules adsorbed on the nanotubes.      

Electron microscopy techniques for the analysis of the polymer electrolyte distribution in proton exchange membrane fuel cells

The polymer electrolyte distribution in PEMFC electrodes plays an important role for the catalyst utilization and various transport processes in the electrode. Moreover, its influence on the transport processes is not only limited to proton transport but it may also affect gas transport, electron conductivity and water management of the cell. However, experimental techniques to study the polymer electrolyte distribution are scarce. In this paper we present various approaches based on scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize the polymer electrolyte distribution. The methods presented include staining of the polymer electrolyte with heavy metal ions, energy dispersive X-ray (EDX) mapping and energy filtered imaging (EFI). Their use for the analysis of the polymer electrolyte distribution and electrode structure will be presented and current limitations of these techniques will be discussed.     

Adipose-Derived Stem Cells in the Treatment of Perianal Fistulas in Crohn’s Disease: Rationale,Clinical Results and Perspectives

Between 20 to 25% of Crohn’s disease (CD) patients suffer from perianal fistulas, a marker of disease severity. Seton drainage combined with anti-TNFα can result in closure of the fistula in 70 to 75% of patients. For the remaining 25% of patients there is room for in situ injection of autologous or allogenic mesenchymal stem cells such as adipose-derived stem/stromal cells (ADSCs). ADSCs exert their effects on tissues and effector cells through paracrine phenomena, including the secretome and extracellular vesicles. They display anti-inflammatory, anti-apoptotic, pro-angiogenic, proliferative, and immunomodulatory properties, and a homing within the damaged tissue. They also have immuno-evasive properties allowing a clinical allogeneic approach. Numerous clinical trials have been conducted that demonstrate a complete cure rate of anoperineal fistulas in CD ranging from 46 to 90% of cases after in situ injection of autologous or allogenic ADSCs. A pivotal phase III-controlled trial using allogenic ADSCs (Alofisel^®) demonstrated that prolonged clinical and radiological remission can be obtained in nearly 60% of cases with a good safety profile. Future studies should be conducted for a better knowledge of the local effect of ADSCs as well as for a standardization in terms of the number of injections and associated procedures.