Solid-state sensors based on Eu3+-containing supramolecular polymers with luminescence colour switching capability.

Polymers that exhibit changes of their luminescence colour in response to external stimuli are attractive candidates for sensing systems. We herein report the preparation of europium-based metallosupramolecular polymers, which can be processed into films and coatings that display readily detectable luminescence colour changes in response to various types of analytes.

Light-responsive azo-containing organogels.

While azo compounds are widely employed as radical initiators, they have rarely been used as stimuli-responsive motifs in macromolecular constructs. In this study, an azo-based cross-linker was prepared and reacted with poly(vinyl alcohol) to afford a series of stimuli-responsive organogels. Irradiation of these materials with UV light causes de-cross-linking and triggers a solid-to-liquid phase transition. Model adhesives with de-bonding-on-demand capability based on this design were explored.

Reprogramming of Pancreatic Acinar Cells to Functional Beta Cells by In Vivo Transduction of a Polycistronic Construct Containing Pdx1, Ngn3, MafA in Mice.

To generate new beta cells after birth is a key focus of regenerative medicine, which could greatly aid the major health burden of diabetes. Beta-cell regeneration has been described using four different approaches: (1) the development of beta cells from putative precursor cells of the adult pancreas, which is termed neogenesis, (2) replication of existing beta cells, (3) differentiation from embryonic or induced pluripotent stem cells, and (4) reprogramming of non-beta cells to beta cells. Studies from the authors' laboratory have shown that beta-cell reprogramming can be achieved by transduction of adult pancreatic tissues with viral constructs containing the three developmentally important transcription factors Pdx1, Ngn3, and MafA. This protocol outlines the generation of a polycistronic construct containing the three transcription factors, the expansion and purification of the polycistronic virus, and in vivo transduction for acinar to beta-cell reprogramming in adult mice. The ultimate goal is to generate beta-like cells that resemble as closely as possible endogenous beta cells in phenotype and function for potential translational applications. © 2017 by John Wiley & Sons, Inc.

A critical review of the current knowledge regarding the biological impact of nanocellulose.

Several forms of nanocellulose, notably cellulose nanocrystals and nanofibrillated cellulose, exhibit attractive property matrices and are potentially useful for a large number of industrial applications. These include the paper and cardboard industry, use as reinforcing filler in polymer composites, basis for low-density foams, additive in adhesives and paints, as well as a wide variety of food, hygiene, cosmetic, and medical products. Although the commercial exploitation of nanocellulose has already commenced, little is known as to the potential biological impact of nanocellulose, particularly in its raw form. This review provides a comprehensive and critical review of the current state of knowledge of nanocellulose in this format. Overall, the data seems to suggest that when investigated under realistic doses and exposure scenarios, nanocellulose has a limited associated toxic potential, albeit certain forms of nanocellulose can be associated with more hazardous biological behavior due to their specific physical characteristics.

Palliative balloon dilation of pulmonic stenosis in a dog with tetralogy of Fallot.

A 6-month-old Beagle with tetralogy of Fallot underwent balloon valvuloplasty of the pulmonary valve. Balloon valvuloplasty was successful and resulted in palliation of clinical signs and an improved quality of life for approximately 9 months. After 9 months, the dog became symptomatic and a modified Blalock-Taussig shunt procedure was successfully performed. Based on this report, balloon valvuloplasty in dogs with tetralogy of Fallot appears to be a feasible technique that may result in improvement of clinical signs. In addition, it may allow for the delay of the more invasive surgical palliation and provide time for weight gain and development of the pulmonary vascular bed for greater ease of surgical shunt creation.

Mechanically adaptive intracortical implants improve the proximity of neuronal cell bodies.

The hypothesis is that the mechanical mismatch between brain tissue and microelectrodes influences the inflammatory response. Our unique, mechanically adaptive polymer nanocomposite enabled this study within the cerebral cortex of rats. The initial tensile storage modulus of 5 GPa decreases to 12 MPa within 15 min under physiological conditions. The response to the nanocomposite was compared to surface-matched, stiffer implants of traditional wires (411 GPa) coated with the identical polymer substrate and implanted on the contralateral side. Both implants were tethered. Fluorescent immunohistochemistry labeling examined neurons, intermediate filaments, macrophages, microglia and proteoglycans. We demonstrate, for the first time, a system that decouples the mechanical and surface chemistry components of the neural response. The neuronal nuclei density within 100 µm of the device at four weeks post-implantation was greater for the compliant nanocomposite compared to the stiff wire. At eight weeks post-implantation, the neuronal nuclei density around the nanocomposite was maintained, but the density around the wire recovered to match that of the nanocomposite. The glial scar response to the compliant nanocomposite was less vigorous than it was to the stiffer wire. The results suggest that mechanically associated factors such as proteoglycans and intermediate filaments are important modulators of the response of the compliant nanocomposite.

In vivo deployment of mechanically adaptive nanocomposites for intracortical microelectrodes.

We recently introduced a series of stimuli-responsive, mechanically adaptive polymer nanocomposites. Here, we report the first application of these bio-inspired materials as substrates for intracortical microelectrodes. Our hypothesis is that the ideal electrode should be initially stiff to facilitate minimal trauma during insertion into the cortex, yet become mechanically compliant to match the stiffness of the brain tissue and minimize forces exerted on the tissue, attenuating inflammation. Microprobes created from mechanically reinforced nanocomposites demonstrated a significant advantage compared to model microprobes composed of neat polymer only. The nanocomposite microprobes exhibit a higher storage modulus (E' = ~5 GPa) than the neat polymer microprobes (E' = ~2 GPa) and can sustain higher loads (~12 mN), facilitating penetration through the pia mater and insertion into the cerebral cortex of a rat. In contrast, the neat polymer microprobes mechanically failed under lower loads (~7 mN) before they were capable of insertion into cortical tissue. Further, we demonstrated the material's ability to morph while in the rat cortex to more closely match the mechanical properties of the cortical tissue. Nanocomposite microprobes that were implanted into the rat cortex for up to eight weeks demonstrated increased cell density at the microelectrode-tissue interface and a lack of tissue necrosis or excessive gliosis. This body of work introduces our nanocomposite-based microprobes as adaptive substrates for intracortical microelectrodes and potentially for other biomedical applications.

Natural biopolymers: novel templates for the synthesis of nanostructures.

Biological systems such as proteins, viruses, and DNA have been most often reported to be used as templates for the synthesis of functional nanomaterials, but the properties of widely available biopolymers, such as cellulose, have been much less exploited for this purpose. Here, we report for the first time that cellulose nanocrystals (CNC) have the capacity to assist in the synthesis of metallic nanoparticle chains. A cationic surfactant, cetyltrimethylammonium bromide (CTAB), was critical to nanoparticle stabilization and CNC surface modification. Silver, gold, copper, and platinum nanoparticles were synthesized on CNCs, and the nanoparticle density and particle size were controlled by varying the concentration of CTAB, the pH of the salt solution, and the reduction time.

Absorption and fluorescence of single molecules.

Simultaneous detection of single molecules by absorption and fluorescence is demonstrated using confocal microscopy at cryogenic temperature. Dynamical processes such as blinking and spectral jumping of single emitters are observed in both detection channels. The relative magnitude of fluorescence and absorption varies between molecules. In particular, we observe molecules that do not emit detectable Stokes-shifted fluorescence but show a strong absorption signal. The fact that coherent resonant scattering underlies the absorption process is demonstrated by a correlation between small linewidth and large absorption amplitude.

Clinical and immune responses correlate in glatiramer acetate therapy of multiple sclerosis.

Glatiramer acetate (GA) treatment for relapsing remitting multiple sclerosis (RRMS) leads to decreased GA-specific proliferative responses and a Th2 cytokine shift. To study a possible correlation between immunological and clinical responses to GA therapy, we prospectively followed RRMS patients clinically, by magnetic resonance imaging and by primary immunological assays. Fluctuation of GA-specific proliferative responses was significantly lower in treatment responders than in untreated patients, and GA-specific proliferative responses were increased during relapses. These associations suggest a possible causal relationship between immunological and clinical responses to GA therapy. Primary proliferation assays may thus be a useful marker for treatment response.

Complexation of unsaturated carbon-carbon bonds in pi-conjugated polymers with transition metals.

The present paper explores the possibility of preparing pi-conjugated organometallic polymer hybrid systems based on a poly(p-phenylene ethynylene) (PPE) derivative, in which the ethynylene moieties of the polymer are coordinated to platinum(II) centers. The use of the "bifunctional" [Pt-(mu-Cl)Cl(PhCH=CH(2))](2) (2) allows, under appropriate conditions, the formation of three-dimensionally cross-linked, conjugated PPE-platinum(II) networks. The synthesis of [Pt-(mu-Cl)Cl(PhC(triple bond)CPh)](2), as a model compound, and a series of model reactions of 2 with diphenylacetylene (3) have enabled an NMR study which has revealed a number of equilibria, and suggests a mixed Pt-styrene-acetylene complex as a key structure. As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift upon complexation with 2.

Influence of supplemental alfalfa quality on the intake, use, and subsequent performance of beef cattle consuming low-quality roughages.

Three experiments were conducted to evaluate influences of supplemental alfalfa quality on intake and use of low-quality meadow grass roughages (MG) by beef cattle. In Exp. 1, 15 steers (250 kg) were assigned to three treatments: 1) MG (5.2% CP), no supplement; 2) MG plus high-quality alfalfa (18.8% CP); and 3) MG plus low-quality alfalfa (15.2% CP). High- and low-quality alfalfa supplements were fed at .45 and .55% BW, respectively. Total DMI was greater (P < .01) for alfalfa-supplemented steers than for MG. Likewise, intake of digestible DM, DM digestibility (DMD), and ruminal ammonia level were greater (P < .01) for supplemented steers. In Exp. 2, 96 pregnant Hereford x Simmental cows (537 kg; body condition [BC] score 4.86) were assigned to the same treatments as in Exp. 1. For d 0 to 42, cows grazed on 19.1 ha of stockpiled MG (4,539 kg/ha; 6.8% CP), whereas, on d 43 to 84, cows received MG hay (5.2% CP). Supplemented cows gained more BW (P < .01), BC score (P < .01), and had heavier calf birth weight (P < .01) than nonsupplemented cows. However, there were no treatment effects (P > .10) on cow cyclicity, pregnancy rate, or calving interval. In Exp. 3, 90 pregnant Angus x Hereford cows (475 kg; BC score 4.59) were assigned to three treatments: 16.1%, 17.8% or 20.0% CP alfalfa supplement, with levels of .63, .55, and .50% of BW, respectively. Weight gain and BC score for the 84-d study displayed a quadratic response (P < .10), yet represented only 7 kg BW and .2 units of BC score. In conclusion, alfalfa hay supplementation was effective in increasing DMI and digestibility. However, alfalfa hay quality did not dramatically affect BW, BC score, and(or) calf birth weight, when fed on an isonitrogenous basis.

Incorporation of photoluminescent polarizers into liquid crystal displays

Liquid crystal displays, the dominant flat panel display technology, are limited in brightness and energy efficiency because of the use of absorbing polarizers and color filters. Liquid crystal-based photoluminescent display devices have been fabricated that use thin, polarized photoluminescent layers that have highly anisotropic absorption or emission. These layers both polarize light and generate bright color. This approach can simplify device design and substantially increase device brightness, contrast, efficiency, and (in specific configurations) viewing angle.

Pseudomembranous colitis associated with antibiotic therapy - an emerging entity.

Two cases of pseudomembranous colitis are presented. The first patient had been treated with novobiocin-tetracycline and penicillin, and two weeks later developed severe fulminating diarrhea with ascites and bilateral pleural effusions which did not respond to intravenous ACTH. Subsequently she underwent subtotal colectomy and made a rapid and complete recovery. The second patient developed severe diarrhea two weeks after a 10-day course of clindamycin. She was treated with intravenous ACTH, oral Lactobacillus and a fecal enema and made a complete recovery.These cases reconfirm the importance of antibiotics as etiologic agents in this disease. They also stress the classic sigmoidoscopic and histologic findings that should facilitate prompt and rapid diagnosis.