850 resultados para stimuli-responsive
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This paper describes the design and erection of a climate-responsive Building Integrated Photovoltaic (BIPV) structure in Bangalore, (12.58 N, 77.38 E) in the state of Karnataka, India. Building Integrated Photovoltaics integrate solar panels as part of a building structure (roofs and walls) with an aim to achieve self-sufficiency in the operation and occupant-comfort energy requirements. A joint collaboration between the Centre for Sustainable Technologies, Indian Institute of Science (IISc) and Bharat Heavy Electricals Limited (BHEL) is setting up a 70,000 US$ facility for research in BIPV structures. The structure utilizes low energy building materials like Stabilized Mud Blocks (SMB) integrated with a PV roof. Numerous challenges were overcome in the design of the BIPV roof including mechanisms for natural thermal comfort in response to Bangalore's climatic conditions. The paper presents the challenges overcome in the design and construction of a low energy, climate-responsive BIPV structure.
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Objective: Glucocorticoid therapy is used worldwide to treat various inflammatory and immune conditions, including inflammatory bowel disease (IBD). In IBD, 80% of the patients obtain a positive response to the therapy; however the development of glucocorticoid-related side-effects is common. Our aim was therefore to study the possibility of optimizing glucocorticoid therapy in children and adolescents with IBD by measuring circulating glucocorticoid bioactivity (GBA) and serum glucocorticoid-responsive biomarkers in patients receiving steroid treatment for active disease. Methods: A total of sixty-nine paediatric IBD patients from the Paediatric Outpatient Clinics of the University Hospitals of Helsinki and Tampere participated in the studies. Control patients included 101 non-IBD patients and 41 disease controls in remission. In patients with active disease, blood samples were withdrawn before the glucocorticoid therapy was started, at 2-4 weeks after the initiation of the steroid and at 1-month intervals thereafter. Clinical response to glucocorticoid treatment and the development of steroid adverse events was carefully registered. GBA was analyzed with a COS-1 cell bioassay. The measured glucocorticoid therapy-responsive biomarkers included adipocyte-derived adiponectin and leptin, bone turnover-related collagen markers amino-terminal type I procollagen propeptide (PINP) and carboxyterminal telopeptide of type I collagen (ICTP) as well as insulin-like growth factor 1 (IGF-1) and sex hormone-binding globulin (SHBG), and inflammatory marker high-sensitivity C-reactive protein (hs-CRP). Results: The most promising marker for glucocorticoid sensitivity was serum adiponectin that associated with steroid therapy–related adverse events. Serum leptin indicated a similar trend. In contrast, circulating GBA rose in all subjects receiving glucocorticoid treatment but did not associate with the clinical response to steroids or with glucocorticoid therapy-related side-effects. Of notice, young patients (<10 years) showed similar GBA levels than older patients, despite receiving higher weight-adjusted doses of glucocorticoid. Markers of bone formation were lower in children with active IBD than in the control patients, probably reflecting the suppressive effect of the active inflammation. The onset of the glucocorticoid therapy further suppressed bone turnover. Inflammatory marker hs-CRP decreased readily after the initiation of the steroid, however the decrease did not associate with the clinical response to glucocorticoids. Conclusions: This is the first study to show that adipocyte-derived adiponectin associates with steroid therapy-induced side-effects. Further studies are needed, but it is possible that the adiponectin measurement could aid the recognition of glucocorticoid-sensitive patients in the future. GBA and the other markers reflecting glucocorticoid activity in different tissues changed during the treatment, however their change did not correlate with the therapeutic response to steroids or with the development of glucocorticoid-related side effects and therefore cannot guide the therapy in these patients. Studies such as as the present one that combine clinical data with newly developed biomolecular technology are needed to step-by-step build a general picture of the glucocorticoid actions in different tissues.
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Research on reading has been successful in revealing how attention guides eye movements when people read single sentences or text paragraphs in simplified and strictly controlled experimental conditions. However, less is known about reading processes in more naturalistic and applied settings, such as reading Web pages. This thesis investigates online reading processes by recording participants eye movements. The thesis consists of four experimental studies that examine how location of stimuli presented outside the currently fixated region (Study I and III), text format (Study II), animation and abrupt onset of online advertisements (Study III), and phase of an online information search task (Study IV) affect written language processing. Furthermore, the studies investigate how the goal of the reading task affects attention allocation during reading by comparing reading for comprehension with free browsing, and by varying the difficulty of an information search task. The results show that text format affects the reading process, that is, vertical text (word/line) is read at a slower rate than a standard horizontal text, and the mean fixation durations are longer for vertical text than for horizontal text. Furthermore, animated online ads and abrupt ad onsets capture online readers attention and direct their gaze toward the ads, and distract the reading process. Compared to a reading-for-comprehension task, online ads are attended to more in a free browsing task. Moreover, in both tasks abrupt ad onsets result in rather immediate fixations toward the ads. This effect is enhanced when the ad is presented in the proximity of the text being read. In addition, the reading processes vary when Web users proceed in online information search tasks, for example when they are searching for a specific keyword, looking for an answer to a question, or trying to find a subjectively most interesting topic. A scanning type of behavior is typical at the beginning of the tasks, after which participants tend to switch to a more careful reading state before finishing the tasks in the states referred to as decision states. Furthermore, the results also provided evidence that left-to-right readers extract more parafoveal information to the right of the fixated word than to the left, suggesting that learning biases attentional orienting towards the reading direction.
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GH3 proteins control auxin homeostasis by inactivating excess auxin as conjugates of amino acids and sugars and thereby controlling cellular bioactive auxin. Since auxin regulates many aspects of plant growth and development, regulated expression of these genes offers a mechanism to control various developmental processes. OsMGH3/OsGH3-8 is expressed abundantly in rice florets and is regulated by two related and redundant transcription factors, OsMADS1 and OsMADS6, but its contribution to flower development is not known. We functionally characterize OsMGH3 by overexpression and knock-down analysis and show a partial overlap in these phenotypes with that of mutants in OsMADS1 and OsMADS6. The overexpression of OsMGH3 during the vegetative phase affects the overall plant architecture, whereas its inflorescence-specific overexpression creates short panicles with reduced branching, resembling in part the effects of OsMADS1 overexpression. In contrast, the down-regulation of endogenous OsMGH3 caused phenotypes consistent with auxin overproduction or activated signaling, such as ectopic rooting from aerial nodes. Florets in OsMGH3 knock-down plants were affected in carpel development and pollen viability, both of which reduced fertility. Some of these floret phenotypes are similar to osmads6 mutants. Taken together, we provide evidence for the functional significance of auxin homeostasis and its transcriptional regulation during rice panicle branching and floret organ development.
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A novel and simple route for near-infrared (NIR)-light controlled release of drugs has been demonstrated using graphene oxide (GO) composite microcapsules based on the unique optical properties of GO. Upon NIR-laser irradiation, the microcapsules were ruptured in a point-wise fashion due to local heating which in turn triggers the light-controlled release of the encapsulated anticancer drug doxorubicin (Dox) from these capsules.
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A novel polyelectrolyte nanocapsule system composed of biopolymers, chitosan and heparin has been fabricated by the layer-by-layer technique on silica nanoparticles followed by dissolution of the silica core. The nanocapsules were of the size range 200 +/- 20 nm and loaded with the positively charged anticancer drug doxorubicin with an efficiency of 89%. The loading of the drug into the capsule happens by virtue of the pH-responsive property of the capsule wall, which is determined by the pKa of the polyelectrolytes. As the pH is varied, about 64% of the drug is released in acidic pH while 77% is released in neutral pH. The biocompatibility, efficiency of drug loading, and enhanced bioavailability of the capsule system was confirmed by MTT assay and in vivo biodistribution studies.
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Background: Genetic variants of NOD2 are linked to inflammatory bowel disease (IBD) etiology. Results: DSS model of colitis in wild-type and inducible nitric-oxide synthase (iNOS) null mice revealed that NOD2-iNOS/NO-responsive microRNA-146a targets NUMB gene facilitating Sonic hedgehog (SHH) signaling. Conclusion: miR-146a-mediated NOD2-SHH signaling regulates gut inflammation. Significance: Identification of novel regulators of IBD provides new insights into pathophysiology and development of new therapy concepts. Inflammatory bowel disease (IBD) is a debilitating chronic inflammatory disorder of the intestine. The interactions between enteric bacteria and genetic susceptibilities are major contributors of IBD etiology. Although genetic variants with loss or gain of NOD2 functions have been linked to IBD susceptibility, the mechanisms coordinating NOD2 downstream signaling, especially in macrophages, during IBD pathogenesis are not precisely identified. Here, studies utilizing the murine dextran sodium sulfate model of colitis revealed the crucial roles for inducible nitric-oxide synthase (iNOS) in regulating pathophysiology of IBDs. Importantly, stimulation of NOD2 failed to activate Sonic hedgehog (SHH) signaling in iNOS null macrophages, implicating NO mediated cross-talk between NOD2 and SHH signaling. NOD2 signaling up-regulated the expression of a NO-responsive microRNA, miR-146a, that targeted NUMB gene and alleviated the suppression of SHH signaling. In vivo and ex vivo studies confirmed the important roles for miR-146a in amplifying inflammatory responses. Collectively, we have identified new roles for miR-146a that established novel cross-talk between NOD2-SHH signaling during gut inflammation. Potential implications of these observations in therapeutics could increase the possibility of defining and developing better regimes to treat IBD pathophysiology.
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Autophagy is one of the major immune mechanisms engaged to clear intracellular infectious agents. However, several pathogens have evolved strategies to evade autophagy. Here, we demonstrated that Mycobacteria, Shigella, and Listeria but not Klebsiella, Staphylococcus, and Escherichia inhibit IFNG-induced autophagy in macrophages by evoking selective and robust activation of WNT and SHH pathways via MTOR. Utilization of gain- or loss-of-function analyses as well as mir155-null macrophages emphasized the role of MTOR-responsive epigenetic modifications in the induction of Mir155 and Mir31. Importantly, cellular levels of PP2A, a phosphatase, were regulated by Mir155 and Mir31 to fine-tune autophagy. Diminished expression of PP2A led to inhibition of GSK3B, thus facilitating the prolonged activation of WNT and SHH signaling pathways. Sustained WNT and SHH signaling effectuated the expression of anti-inflammatory lipoxygenases, which in tandem inhibited IFNG-induced JAK-STAT signaling and contributed to evasion of autophagy. Altogether, these results established a role for new host factors and inhibitory mechanisms employed by the pathogens to limit autophagy, which could be targeted for therapeutic interventions.
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Saccharomyces boulardii was encapsulated by layer-by-layer technique (LbL) using oppositely charged polyelectrolytes, chitosan and dextran sulfate to protect from degradation during its gastrointestinal transit. The protective effect of the coating was evaluated by checking viability after subjecting the coated cells to lyophilisation and simulated gastrointestinal conditions. During lyophilization, coated S. boulardii was found to have an enhanced viability of 7.74 +/- 2.00 log CFU/100 mg (5.62 x 10(6) +/- 2.12 CFU/100 mg) and 5.53 +/- 1.85 log CFU/100 mg (3.46 x 10(5) 1.73 CFU/100 mg) for uncoated cells. On sequential treatment with simulated gastric and intestinal juice, the coated cells had a viability of 4.59 +/- 1.52 log CFU/100 mg (3.8 x 104 +/- 1.52 CFU/100 mg) while only 1.90 +/- 0.80 log CFU/100 mg (0.79 x 102 +/- 0.81 CFU/100 mg) of uncoated cells survived. Confocal studies displayed the selective permeability of the coated cells which plays a significant role in maintaining the integrity and viability of the yeast cells. This clearly indicates that LbL is an efficient protective encapsulation technique and it could be potentially used for improving therapeutic applications of yeast. (C) 2014 Elsevier Ltd. All rights reserved.
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In the context of the role of multiple physical factors in dictating stem cell fate, the present paper demonstrates the effectiveness of the intermittently delivered external electric field stimulation towards switching the stem cell fate to specific lineage, when cultured in the absence of biochemical growth factors. In particular, our findings present the ability of human mesenchymal stem cells (hMSCs) to respond to the electric stimuli by adopting extended neural-like morphology on conducting polymeric substrates. Polyaniline (PANI) is selected as the model system to demonstrate this effect, as the electrical conductivity of the polymeric substrates can be systematically tailored over a broad range (10(-9) to 10 S/cm) from highly insulating to conducting by doping with varying concentrations (10(-5) to 1 M) of HCl. On the basis of the culture protocol involving the systematic delivery of intermittent electric field (dc) stimulation, the parametric window of substrate conductivity and electric field strength was established to promote significant morphological extensions, with minimal cellular damage. A time dependent morphological change in hMSCs with significant filopodial elongation was observed after 7 days of electrically stimulated culture. Concomitant with morphological changes, a commensurate increase in the expression of neural lineage commitment markers such as nestin and PI tubulin was recorded from hMSCs grown on highly conducting substrates, as revealed from the mRNA expression analysis using Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) as well as by immune-fluorescence imaging. Therefore, the present work establishes the key role of intermittent and systematic delivery of electric stimuli as guidance cues in promoting neural-like differentiation of hMSCs, when grown on electroconductive substrates. (C) 2014 Elsevier Ltd. All rights reserved.
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We report the fabrication of dual enzyme responsive hollow nanocapsules which can be targeted to deliver anticancer agents specifically inside cancer cells. The enzyme responsive elements, integrated in the nanocapsule walls, undergo degradation in the presence of either trypsin or hyaluronidase leading to the release of encapsulated drug molecules. These nanocapsules, which were crosslinked and functionalised with folic acid, showed minimal drug leakage when kept in pH 7.4 PBS buffer, but released the drug molecules at a rapid rate in the presence of either one of the triggering enzymes. Studies on cellular interactions of these nanocapsules revealed that doxorubicin loaded nanocapsules were taken up by cervical cancer cells via folic acid receptor medicated endocytosis. Interestingly the nanocapsules were able to disintegrate inside the cancer cells and release doxorubicin which then migrated into the nucleus to induce cell death. This study indicates that these nanocapsules fabricated from biopolymers can serve as an excellent platform for targeted intracellular drug delivery to cancer cells.
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Several covalent strategies towards surface charge-reversal in nanochannels have been reported with the purpose of manipulating ion transport. However, covalent routes lack dynamism, modularity and post-synthetic flexibility, and hence restrict their applicability in different environments. Here, we introduce a facile non-covalent approach towards charge-reversal in nanochannels (< 10 nm) using strong charge-transfer interactions between dicationic viologen (acceptor) and trianionic pyranine (donor). The polarity of ion transport was switched from anion selective to ambipolar to cation selective by controlling the extent of viologen bound to the pyranine. We could also regulate the ion transport with respect to pH by selecting a donor with pH-responsive functional groups. The modularity of this approach further allows facile integration of various functional groups capable of responding to stimuli such as light and temperature to modulate the transport of ions as well as molecules.
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Copper(II) and copper(I) complexes of a newly designed and crystallographically characterized Schiff base (HL) derived from rhodamine hydrazide and cinnamaldehyde were isolated in pure form formulated as Cu(L)(NO3)] (L-Cu) (1) and Cu(HL)(CH3CN)(H2O)]ClO4 (HL-Cu) (2), and characterized by physicochemical and spectroscopic tools. Interestingly, complex 1 but not 2 offers red fluorescence in solution state, and eventually HL behaves as a Cu(II) ions selective FRET based fluorosensor in HEPES buffer (1 mM, acetonitrile-water: 1/5, v/v) at 25 degrees C at biological pH with almost no interference of other competitive ions. The dependency of the FRET process on the +2 oxidation state of copper has been nicely supported by exhaustive experimental studies comprising electronic, fluorimetric, NMR titration, and theoretical calculations. The sensing ability of HL has been evaluated by the LOD value towards Cu(II) ions (83.7 nM) and short responsive time (5-10 s). Even the discrimination of copper(I) and copper(II) has also been done using only UV-Vis spectroscopic study. The efficacy of this bio-friendly probe has been determined by employing HL to detect the intercellular distribution of Cu(II) ions in HeLa cells by developing image under fluorescence microscope.
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A novel, micro-shock wave responsive spermidine and dextran sulfate microparticle was developed. Almost 90% of the drug release was observed when the particles were exposed to micro-shock waves 5 times. Micro-shock waves served two purposes; of releasing the antibiotic from the system and perhaps disrupting the S. aureus biofilm in the skin infection model. A combination of shock waves with ciprofloxacin loaded microparticles could completely cure the S. aureus infection lesion in a diabetic mouse model. As a proof of concept insulin release was triggered using micro-shock waves in diabetic mice to reduce the blood glucose level. Insulin release could be triggered for at least 3 days by exposing subcutaneously injected insulin loaded particles.
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Ammonia plays an important role in our daily lives and hence its quantitative and qualitative sensing has become necessary. Bulk structure of carbon nanotubes (CNTs) has been employed to detect the gas concentration of 10 ppm. Hydrophobic CNTs were turned to hydrophilic via the application of a ramp electric field that allowed confinement of a controlled amount of water inside CNT microstructure. These samples were then also used to detect different gases. A comparative study has been performed for sensing three reducing gases, namely, ammonia, sulphur-di-oxide, and hydrogen sulphide to elaborate the selectivity of the sensor. A considerable structural bending in the bulk CNT was observed on evaporation of the confined water, which can be accounted to the zipping of individual nanotubes. However, the rate of the stress induced on these bulk microstructures increased on the exposure of ammonia due to the change in the surface tension of the confined solvent. A prototype of an alarm system has been developed to illustrate sensing concept, wherein the generated stress in the bulk CNT induces a reversible loss in electrical contact that changes the equivalent resistance of the electrical circuit upon exposure to the gas. (C) 2015 AIP Publishing LLC.