Textural, viscoelastic and mucoadhesive properties of pharmaceutical gels composed of cellulose polymers

This study examined the mechanical/textural, viscoeiastic and mucoadhesive properties of a range of aqueous gels composed of either hydroxyethylcellulose (HEC) or sodium carboxymethylcellulose (Na CMC). The mechanical/textural properties of each formulation were determined using texture profile analysis. The viscoelastic properties of each formulation were examined over a defined frequency range (0.01-1.0 Hz) using oscillatory rheometry in conjunction with stainless steel parallel plate geometry. The mucoadhesive properties of the gels were evaluated by measuring the tensile force required to overcome the gel/mucin adhesive interaction. Both gel hardness and compressibility, properties that affect the ease of product removal from a container and spreadability, increased as a function of increasing polymer concentrations. This is attributed to the effects of HEC and Na CMC on gel viscosity. Gel adhesiveness, a property related to bioadhesion, also increased as a function of polymer concentration and is attributed to the reported adhesive nature of these polymers. Increasing frequency of oscillation increased the storage and loss moduli yet decreased bath the dynamic viscosity of each gel type and also the loss tangent of HEC (but not Na CMC) gels. Therefore, following exposure to the range of oscillatory stresses that may be expected in vivo, HEC gels will be more susceptible than Na CMC gels to alterations in these rheological properties. Consequently, it would be expected that the clinical performance of HEC gels will be modified to a greater extent than Na CMC gels. In general, HEC gels exhibited a greater elastic nature than Na CMC gels over the frequency range employed for oscillation The storage and loss moduli and dynamic viscosity of both gel types increased, yet the loss tangent of both gel types decreased as a function of increasing polymer concentration. Gel mucoadhesive strength was dependent on both the time of contact of the formulation with mucin and also on polymer concentration. In conclusion, this study has characterised a number of gels containing either HEC or Na CMC in terms of their mechanical/textural, viscoelastic and mucoadhesive properties. Due to its relevance to the clinical performance, it is suggested that the information derived from these methods may be usefully combined to provide a more rational basis for the selection of polymers and their formulation as topical drug delivery systems. (C) 1997 Elsevier Science B.V.

Modification of biomaterial surface characteristics by body fluids in vitro

In practice, polyvinyl chloride endotracheal tubes and polyurethane urinary catheters are located in areas where they are exposed to the conditioning fluids saliva and urine, respectively. Samples of both biomaterials were incubated in these conditioning fluids and, following treatment, dynamic contact angle measurement and surface roughness assessment by atomic force microscopy were used to analyse surface characteristics. Over a 24 h period of contact with the conditioning fluids, the surface of both materials became significantly more hydrophilic (p

Interfacial Properties of LiTFSI and LiPF6-Based Electrolytes in Binary and Ternary Mixtures of Alkylcarbonates on Graphite Electrodes and Celgard Separator

For a better understanding of the adsorption behavior of alkylcarbonate-based electrolytes on graphite electrodes and Celgard separator for Li-ion batteries applications, the interface parameters are determined by contact angle and surface tension measurements. The correlation between these parameters and chemical compositions made of alkyl carbonate with a varying nature of lithium salts (LiPF6 and LiTFSI) and volume fractions of binary and ternary mixtures containing propylene carbonate (PC), ethylene carbonate (EC), and dimethyl carbonate (DMC) is investigated. From the obtained contact angle and surface tension (?L) values for each liquid, the dispersive and polar components of the surface tension (?Ld and ?Lp) of the electrolyte and interfacial free energy between the solid and liquid (?SL) were then calculated using the Young’s equation. The variation of contact angle (?) and the surface tension, as well as the work of adhesion (WA) of binary PC/DMC mixtures on PP, PE, and PET model surfaces were also measured and commented as function of volume fraction of PC in DMC. Finally, the Zisman’s critical surface tension (?C) for studied surfaces was then obtained showing positives slopes of cos ? versus ?L. This behavior is explained by a relative higher adsorption of alkylcarbonates to the hydrogenated supports or graphite. These results are decisive to understand the performance of electrolyte/electrode material/separator interfaces in lithium-ion battery devices.

THE ORGANIZATION OF THE NERVOUS-SYSTEM IN PLATHELMINTHES - THE NEUROPEPTIDE F-IMMUNOREACTIVE PATTERN IN CATENULIDA, MACROSTOMIDA, PROSERIATA

The organization of the nervous system of Archilopsis unipunctata Promonotus schultzei and Paramonotus hamatus (Monocelididae, Proseriata) and Stenostomum leucops (Catenulida) and Microstomum lineare (Macrostomida) was studied by immunocytochemistry, using antibodies to the authentic flatworm neuropeptide F (NPF) (Moniezia expansa). The organization of the nervous system of the Monocelididae was compared to that of the nervous system of Bothriomolus balticus (Otoplanidae), a previously studied species of another family of the Proseriata. The results show that the main nerve cords (MCs), independent of lateral or ventral position in the Monocelididae and the Otoplanidae, correspond to each other. The study also confirms the status of the lateral cords as main cords (MCs) in S. leucops and M. lineare. Common for MCs in the members of the investigated taxa are the following features: MCs consist of many fibres, originate from the brain and are adjoined to 5-HT-positive neurons. In Monocelididae and Otoplanidae, the MCs additionally have the same type of contact to the pharyngeal nervous system. Also common for both proseriate families is the organization of the two lateral nerve cords, with weaker connections to the brain, and the pair of dorsal cords running above the brain. The organization of the minor cords differs. The Monocelididae have a pair of thin ventral cords forming a mirror image of the dorsal pair. Furthermore, an unpaired ventral medial cord connecting medial commissural cells was observed in P. schultzei. Marginal nerve cords, observed in Otoplanidae, are absent in Monocelididae. All minor nerve cords are closely connected to the peripheral nerve plexus. The postulated trends of condensation of plexal fibres to cords and/or the flexibility of the peripheral nerve plexus are discussed. In addition, the immunoreactivity (IR) pattern of NPF was compared to the IR patterns of the neuropeptide RFamide and the indoleamine, 5-HT (serotonin). Significant differences between the distribution of IR to NPF and to 5-HT occur. 5-HT-IR dominates in the submuscular and subepidermal plexuses. In the stomatogastric plexus of M. lineare, only peptidergic IR is observed in the intestinal nerve net. The distribution of NPF-IR in fibres and cells of the intestinal wall in M. lineare indicates a regulatory function for this peptide in the gut, while a relationship with ciliary and muscular locomotion is suggested for the 5-HT-IR occurring in the subepidermal and submuscular nerve plexuses. In M. lineare, the study revealed an NPF- and RFamide-positive cell pair, marking the finished development of new zooids. This finding indicates that constancy of these cells is maintained in this asexually reproducing and regenerating species.

Surface localisation of photosensitisers on intraocular lens biomaterials for prevention of infectious endophthalmitis and retinal protection

Cataract surgery is one of the most commonly-practiced surgical procedures in Western medicine, and, while complications are rare, the most serious is infectious postoperative endophthalmitis. Bacteria may adhere to the implanted intraocular lens (IOL) and subsequent biofilm formation can lead to a chronic, difficult to treat infection. To date, no method to reduce the incidence of infectious endophthalmitis through bacterial elimination, while retaining optical transparency, has been reported. In this study we report a method to optimise the localisation of a cationic porphyrin at the surface of suitable acrylate copolymers, which is the first point of contact with potential pathogens. The porphyrin catalytically generates short-lived singlet oxygen, in the presence of visible light, which kills adherent bacteria indiscriminately. By restricting the photosensitiser to the surface of the biomaterial, reduction in optical transparency is minimised without affecting efficacy of singlet oxygen production. Hydrogel IOL biomaterials incorporating either methacrylic acid (MAA) or methyl methacrylate (MMA) co-monomers allow tuning of the hydrophobic and anionic properties to optimise the localisation of porphyrin. Physiochemical and antimicrobial properties of the materials have been characterised, giving candidate materials with self-generating, persistent anti-infective character against Gram-positive and Gram-negative organisms. Importantly, incorporation of porphyrin can also serve to protect the retina by filtering damaging shortwave visible light, due to the Soret absorption (?max) 430 nm). © 2012 Elsevier Ltd. All rights reserved.

Langerhans cells protect from allergic contact dermatitis in mice by tolerizing CD8+ T cells and activating Foxp3+ regulatory T cells

Allergic contact dermatitis is the most frequent occupational disease in industrialized countries. It is caused by CD8(+) T cell-mediated contact hypersensitivity (CHS) reactions triggered at the site of contact by a variety of chemicals, also known as weak haptens, present in fragrances, dyes, metals, preservatives, and drugs. Despite the myriad of potentially allergenic substances that can penetrate the skin, sensitization is relatively rare and immune tolerance to the substance is often induced by as yet poorly understood mechanisms. Here we show, using the innocuous chemical 2,4-dinitrothiocyanobenzene (DNTB), that cutaneous immune tolerance in mice critically depends on epidermal Langerhans cells (LCs), which capture DNTB and migrate to lymph nodes for direct presentation to CD8(+) T cells. Depletion and adoptive transfer experiments revealed that LCs conferred protection from development of CHS by a mechanism involving both anergy and deletion of allergen-specific CD8(+) T cells and activation of a population of T cells identified as ICOS(+)CD4(+)Foxp3(+) Tregs. Our findings highlight the critical role of LCs in tolerance induction in mice to the prototype innocuous hapten DNTB and suggest that strategies targeting LCs might be valuable for prevention of cutaneous allergy.

Imagining intergroup contact reduces implicit prejudice

Recent research has demonstrated that imagining intergroup contact can be sufficient to reduce explicit prejudice directed towards out-groups. In this research, we examined the impact of contact-related mental imagery on implicit prejudice as measured by the implicit association test. We found that, relative to a control condition, young participants who imagined talking to an elderly stranger subsequently showed more positive implicit attitudes towards elderly people in general. In a second study, we demonstrated that, relative to a control condition, non-Muslim participants who imagined talking to a Muslim stranger subsequently showed more positive implicit attitudes towards Muslims in general. We discuss the implications of these findings for furthering the application of indirect contact strategies aimed at improving intergroup relations.

Can Imagined Interactions Produce Positive Perceptions? Reducing Prejudice Through Simulated Social Contact

The contact hypothesis states that, under the right conditions, contact between members of different groups leads to more positive intergroup relations. The authors track recent trends in contact theory to the emergence of extended, or indirect, forms of contact. These advances lead to an intriguing proposition: that simply imagining intergroup interactions can produce more positive perceptions of outgroups. The authors discuss empirical research supporting the imagined contact proposition and find it to be an approach that is at once deceptively simple and remarkably effective. Encouraging people to mentally simulate a positive intergroup encounter leads to improved outgroup attitudes and reduced stereotyping. It curtails intergroup anxiety and extends the attribution of perceivers' positive traits to others. The authors describe the advantages and disadvantages of imagined contact compared to conventional strategies, outline an agenda for future research, and discuss applications for policymakers and educators in their efforts to encourage more positive intergroup relations.

Recurrence of Urothelial Carcinoma of the Bladder: A Role for Insulin-Like Growth Factor-II Loss of Imprinting and Cytoplasmic E-Cadherin Immunolocalization

Purpose:This study documents the frequency of insulin-like growth factor-II (IGF-II) loss of imprinting (LOI) in a series of 87 bladder tissues. E-cadherin (CDH1) immunolocalization was also investigated due to the known redistribution of this adherence protein to the cytoplasm following exogenous exposure to IGF-II.
Experimental Design: Informative IGF-II cases were identified following DNA-PCR amplification and subsequent sequencing of the transcribable ApaI RFLP in exon 9 of IGF-II. Similar approaches using primer-specific cDNA templates identified the imprinting status of IGF-II in these informative cases. CDH1cellular localization was assessed on a tissue microarray platform of 114 urothelial carcinoma of the bladder (UCB) cases (70 pTanoninvasive and 44 pT1laminapropria invasive) using the commercially available Novocastra antibody.
Results: IGF-IILOI was evident in 7 of17 (41%) UCB tumors and 4 of11 (36%) tumor-associated normal urothelial samples.Two of four pT1grade 3 tumors, the subject of much debate concerning their suitability for radical cystectomy, showed LOI at the IGF-II locus. In those tumors showing IGF-II LOI, 4 of 7 (57%) displayed concomitant CDH1cytoplasmic staining. In contrast, only 3 of 10 (30%) IGF-IImaintenance ofimprinting tumorshad concomitant CDH1cytoplasmiclocalization. UCB cell lines displaying cytoplasmic CDH1immunolocalization expressed significantly higher levels of IGF-II (CAL29, HT1376, and RT112) compared with RT4, a cell line displaying crisp membranous CDH1staining. Finally, cytoplasmic CDH1staining was an independent predictor of a shorter time to recurrence independent of tumor grade and stage.
Conclusions: We suggest that CDH1 cytoplasmic immunolocalization as a result of increased IGF-II levels identifies those nonmuscle invasive presentations most likely to recur and therefore might benefit from more radical nonconserving bladder surgery

Contact and context: sharing education and building relationships in a divided society

One approach to tackling problems of division in society has been to promote collaboration and engagement between schools separated on ethno-religious lines. Based on some variant of contact theory, the received wisdom is that inter-group encounters can contribute to prejudice reduction and promote more harmonious relationships. Evidence to support this analysis is convincing; however, relatively little is known about the environmental factors that impede or enhance the potential for contact in different contexts. The importance of understanding such factors is underscored in divided jurisdictions, where separate education has been linked to the perpetuation of division and hostility. This paper adopts a qualitative approach to exploring the impact of two inter-school initiatives in Northern Ireland. The projects are located in contrasting socio-political and demographic environments, and research findings point to very different contact outcomes for participants in each. Seemingly relevant factors include the degree of congruence between school and community norms and values, the opportunity to develop relationships outside the school context, the relationships developed between the schools and local communities and the historical, political and social referents used by individuals to navigate the contact experience. The paper concludes with some reflections on factors that may help foster social harmony and on potential policy implications of the findings.

Preliminary investigation of mixed adsorbents for the removal of copper and methylene blue from aqueous solutions

With most recent studies being focused on the development of
advanced chemical adsorbents, this paper investigates the possibility of
using two natural low-cost materials for selective adsorption. Multiadsorbent
systems containing tea waste and dolomite have been tested for
their effectiveness in the removal of copper and methylene blue from
aqueous solutions. The effects of contact time, solution pH and
adsorption isotherms on the sorption behaviour were investigated. The
Langmuir and Freundlich isotherms adequately described the adsorption of
copper ions and methylene blue by both materials in different systems.
The highest adsorption capacities for Cu and MB were calculated as 237.7
at pH 4.5 and 150.44 mg.g‒1 at pH 7 for DO and TW+DO respectively. Tea
waste (TW) and dolomite (DO) were characterized by Fourier transform
infrared spectroscopy, scanning electron microscopy and Energy dispersive
X-ray analysis. The removal of Cu and MB by dolomite was mainly via
surface complexation while physisorption was responsible for most of the
Cu and MB adsorption onto tea waste. Identifying the fundamental mechanisms and behaviour is key to the development of practical multi-adsorbent packed columns.

‘Plugging the Gap’: Shared Education and the promotion of community relations through schools in Northern Ireland

Although there is no consensus amongst educationalists as to the role schools play as drivers of hostilities in divided societies, there is broad agreement that they can facilitate more positive intergroup relations. In Northern Ireland the promotion of school based inter-group contact has been offered as a means through which this can happen. Until 2007, the approach was twofold, reflected on the one hand in short-term contact opportunities for pupils in predominantly Catholic and Protestant schools, and on the other, in support for integrated schools which educate Catholics and Protestants together. In 2007 the Shared Education Programme was introduced to ‘bridge the gap’ between short-term opportunities for contact, and ‘full immersion’ integrated schools. Informed by contact theory, shared education offers curriculum based interaction between pupils attending all school types, aimed at promoting the type of contact likely to reduce negative social attitudes and ultimately contribute to social harmony. In this paper, we examine the impact of shared education thus far. Our analysis suggests that whilst shared education is generally effective in promoting positive assessments of other group members, there is a danger that programme impact may be inhibited by the foregrounding of educational over reconciliation priorities. Appreciating that the downplaying reconciliation objectives may have been necessary when the programme was established in order to maximize recruitment to it, we argue that if the full potential of shared education is to be realized, moving forward, it is important for schools to engage with issues of group differences.

Does social deprivation influence inter-group contact outcomes for pupils in Northern Ireland?

The education system in Northern Ireland is characterized by division, with
around 95% of the pupil population attending predominantly co-religionist
schools. In a society that is transitioning from a thirty year conflict that has been
framed by hostilities between the main Catholic and Protestant communities, reconciliation
interventions in education have sought to promote the value of intergroup
contact between pupils attending separate schools. Some qualitative research
suggests that such initiatives are more likely to have positive outcomes for
pupils from more middle class backgrounds than those from more disadvantaged
communitiesand areas that experienced high levels of conflict related incidents and deaths during the pre-ceasefire years. Drawing on contact theory and empirical evidence from a large scale quantitative study, we seek to examine this theory. Using free school meals as a proxy for social class, our findings are consistent in finding that there is a differential impact of contact for those from less affluent backgrounds, and we conclude by arguing that this should be reflected in policy responses.

The Imagined Contact Hypothesis

Imagined intergroup contact (Crisp & Turner, 2009) is a new indirect contact strategy for promoting tolerance and more positive intergroup relations. Research has shown that mentally simulating a positive interaction with an outgroup member can elicit more favorable explicit and implicit outgroup attitudes, less stereotyping, and enhance intentions to engage in future contact. This review documents the range of benefits that accrue from imagined contact, the processes through which it operates, and the conditions that limit or enhance its effectiveness. Studies have shown when, how, and why imagining contact reduces prejudice against a range of different target groups, and how it can be integrated with existing contact-based approaches to provide maximally effective strategies for improving intergroup relations. The approach is not without its critics, and this review addresses the controversies and debates stimulated by imagined contact theory and research. The review concludes with a discussion of the value that imagery techniques can bring to implementations of contact theory, and how the approach offers a new, flexible, and effective tool for practitioners and policy makers in their efforts to promote, encourage, and enhance more harmonious intergroup relations.