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Sample records for nanoparticles induces transient

  1. Internalization of mesoporous silica nanoparticles induces transient but not sufficient osteogenic signals in human mesenchymal stem cells

    SciTech Connect

    Huang, D.-M. Chung, T.-H.; Hung, Y.; Lu, F.; Wu, S.-H.; Mou, C.-Y.; Yao, M.; Chen, Y.-C.

    2008-09-01

    The biocompatibility of nanoparticles is the prerequisite for their applications in biomedicine but can be misleading due to the absence of criteria for evaluating the safety and toxicity of those nanomaterials. Recent studies indicate that mesoporous silica nanoparticles (MSNs) can easily internalize into human mesenchymal stem cells (hMSCs) without apparent deleterious effects on cellular growth or differentiation, and hence are emerging as an ideal stem cell labeling agent. The objective of this study was to thoroughly investigate the effect of MSNs on osteogenesis induction and to examine their biocompatibility in hMSCs. Uptake of MSNs into hMSCs did not affect the cell viability, proliferation and regular osteogenic differentiation of the cells. However, the internalization of MSNs indeed induced actin polymerization and activated the small GTP-bound protein RhoA. The MSN-induced cellular protein responses as believed to cause osteogenesis of hMSCs did not result in promotion of regular osteogenic differentiation as analyzed by cytochemical stain and protein activity assay of alkaline phosphatase (ALP). When the effect of MSNs on ALP gene expression was further examined by reverse transcriptase polymerase chain reaction, MSN-treated hMSCs were shown to have significantly higher mRNA expression than control cells after 1-hour osteogenic induction. The induction of ALP gene expression by MSNs, however, was absent in cells after 1-day incubation with osteogenic differentiation. Together our results show that the internalization of MSNs had a significant effect on the transient protein response and osteogenic signal in hMSCs, thereby suggesting that the effects of nanoparticles on diverse aspects of cellular activities should be carefully evaluated even though the nanoparticles are generally considered as biocompatible at present.

  2. Monitoring of transient cavitation induced by ultrasound and intense pulsed light in presence of gold nanoparticles.

    PubMed

    Sazgarnia, Ameneh; Shanei, Ahmad; Shanei, Mohammad Mahdi

    2014-01-01

    One of the most important challenges in medical treatment is invention of a minimally invasive approach in order to induce lethal damages to cancer cells. Application of high intensity focused ultrasound can be beneficial to achieve this goal via the cavitation process. Existence of the particles and vapor in a liquid decreases the ultrasonic intensity threshold required for cavitation onset. In this study, synergism of intense pulsed light (IPL) and gold nanoparticles (GNPs) has been investigated as a means of providing nucleation sites for acoustic cavitation. Several approaches have been reported with the aim of cavitation monitoring. We conducted the experiments on the basis of sonochemiluminescence (SCL) and chemical dosimetric methods. The acoustic cavitation activity was investigated by determining the integrated SCL signal acquired over polyacrylamide gel phantoms containing luminol in the presence and absence of GNPs in the wavelength range of 400-500 nm using a spectrometer equipped with cooled charged coupled devices (CCD) during irradiation by different intensities of 1 MHz ultrasound and IPL pulses. In order to confirm these results, the terephthalic acid chemical dosimeter was utilized as well. The SCL signal recorded in the gel phantoms containing GNPs at different intensities of ultrasound in the presence of intense pulsed light was higher than the gel phantoms without GNPs. These results have been confirmed by the obtained data from the chemical dosimetry method. Acoustic cavitation in the presence of GNPs and intense pulsed light has been suggested as a new approach designed for decreasing threshold intensity of acoustic cavitation and improving targeted therapeutic effects.

  3. Myocardial Delivery of Lipidoid Nanoparticle Carrying modRNA Induces Rapid and Transient Expression

    PubMed Central

    Turnbull, Irene C; Eltoukhy, Ahmed A; Fish, Kenneth M; Nonnenmacher, Mathieu; Ishikawa, Kiyotake; Chen, Jiqiu; Hajjar, Roger J; Anderson, Daniel G; Costa, Kevin D

    2016-01-01

    Nanoparticle-based delivery of nucleotides offers an alternative to viral vectors for gene therapy. We report highly efficient in vivo delivery of modified mRNA (modRNA) to rat and pig myocardium using formulated lipidoid nanoparticles (FLNP). Direct myocardial injection of FLNP containing 1–10 μg eGFPmodRNA in the rat (n = 3 per group) showed dose-dependent enhanced green fluorescent protein (eGFP) mRNA levels in heart tissue 20 hours after injection, over 60-fold higher than for naked modRNA. Off-target expression, including lung, liver, and spleen, was <10% of that in heart. Expression kinetics after injecting 5 μg FLNP/eGFPmodRNA showed robust expression at 6 hours that reduced by half at 48 hours and was barely detectable at 2 weeks. Intracoronary administration of 10 μg FLNP/eGFPmodRNA also proved successful, although cardiac expression of eGFP mRNA at 20 hours was lower than direct injection, and off-target expression was correspondingly higher. Findings were confirmed in a pilot study in pigs using direct myocardial injection as well as percutaneous intracoronary delivery, in healthy and myocardial infarction models, achieving expression throughout the ventricular wall. Fluorescence microscopy revealed GFP-positive cardiomyocytes in treated hearts. This nanoparticle-enabled approach for highly efficient, rapid and short-term mRNA expression in the heart offers new opportunities to optimize gene therapies for enhancing cardiac function and regeneration. PMID:26471463

  4. Current transients in single nanoparticle collision events.

    PubMed

    Xiao, Xiaoyin; Fan, Fu-Ren F; Zhou, Jiping; Bard, Allen J

    2008-12-10

    Electrochemical hydrazine oxidation and proton reduction occur at a significantly higher rate at Pt than at Au or C electrodes. Thus, the collision and adhesion of a Pt particle on a less active Au or C electrode leads to a large current amplification by electrocatalysis at single nanoparticles (NPs). At low particle concentrations, the collision of Pt NPs was characterized by current transients composed of individual current profiles that rapidly attained a steady state, signaling single NP collisions. The characteristic steady-state current was used to estimate the particle size. The fluctuation in collision frequency with time indicates that the collision of NPs at the detector electrodes occurs in a statistically random manner, with the average frequency a function of particle concentration and diffusion coefficient. A longer term current decay in single current transients, as opposed to the expected steady-state behavior, was more pronounced for proton reduction than for hydrazine oxidation, revealing microscopic details of the nature of the particle interaction with the detector electrode and the kinetics of electrocatalysis at single NPs. The study of single NP collisions allows one to screen particle size distributions and estimate NP concentrations and diffusion coefficients.

  5. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media

    NASA Astrophysics Data System (ADS)

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M.; Luna, Mónica; Briones, Fernando

    2012-04-01

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles’ performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications.

  6. Transient birefringence effects in electromagnetically induced transparency

    SciTech Connect

    Parshkov, O M

    2015-11-30

    We report the results of numerical modelling of transient birefringence that arises as a result of electromagnetically induced transparency on degenerate quantum transitions between the states with J = 0, 1 and 2 in the presence of the Doppler broadening of spectral lines. It is shown that in the case of a linearly polarised control field, the effect of transient birefringence leads to a decay of the input circularly polarised probe pulse into separate linearly polarised pulses inside a medium. In the case of a circularly polarised control field, the effect of transient birefringence manifests itself in a decay of the input linearly polarised probe pulse into separate circularly polarised pulses. It is shown that the distance that a probe pulse has to pass in a medium before decaying into subpulses is considerably greater in the first case than in the second. The influence of the input probe pulse power and duration on the process of spatial separation into individual pulses inside a medium is studied. A qualitative analysis of the obtained results is presented. (nonlinear optical phenomena)

  7. Stress induces transient auditory hypersensitivity in rats.

    PubMed

    Mazurek, Birgit; Haupt, Heidemarie; Joachim, Ricarda; Klapp, Burghard F; Stöver, Timo; Szczepek, Agnieszka J

    2010-01-01

    Exposure to harsh environment induces stress reactions that increase probability of survival. Stress influences the endocrine, nervous and immune systems and affects the functioning of a variety of organs. Numerous researchers demonstrated that a 24-h exposure to an acoustic rodent repellent provokes stress reaction in exposed animals. In addition to the activated hypothalamic-pituitary-adrenal (HPA) axis, exposed animals had pathological reactions in the reproductive organs, bronchia and skin. Here, we examined the effect of above stress model on the auditory system of Wistar rats. We found that 24-h stress decreases the thresholds and increases the amplitudes of auditory brainstem responses and distortion product otoacoustic emissions. Resultant auditory hypersensitivity was transient and most pronounced between 3 and 6h post-stress, returning to control levels one week later. The concentration of corticosterone and tumor necrosis factor alpha was systemically elevated in stressed animals between 3 and 6h post-stress, confirming the activation of the HPA axis. In addition, expression of the HPA-axis-associated genes: glucocorticoid receptor (GR) and hypoxia-inducible factor 1 alpha (Hif1a) was modulated in the auditory tissues. In detail, in the inferior colliculus, we found an up-regulation of GR mRNA 3h post-stress and continuous up-regulation of Hif1a up to 24h post-stress. In the spiral ganglion, we found no differences in gene expression between stressed and control animals. In the organ of Corti, expression of GR mRNA remained stable, whereas that of Hif1a was significantly down-regulated one week after stress. In addition, the expression of an outer hair cell marker prestin was significantly up-regulated 6h post-stress. We conclude that 24-h stress induces transient hypersensitivity of the auditory system and modulates gene expression in a tissue-specific manner. Stress-induced auditory hypersensitivity could have evolutionary consequence by giving animals

  8. Laser-induced transient grating setup with continuously tunable period

    SciTech Connect

    Vega-Flick, A.; Eliason, J. K.; Maznev, A. A.; Nelson, K. A.; Khanolkar, A.; Abi Ghanem, M.; Boechler, N.; Alvarado-Gil, J. J.

    2015-12-15

    We present a modification of the laser-induced transient grating setup enabling continuous tuning of the transient grating period. The fine control of the period is accomplished by varying the angle of the diffraction grating used to split excitation and probe beams. The setup has been tested by measuring dispersion of bulk and surface acoustic waves in both transmission and reflection geometries. The presented modification is fully compatible with optical heterodyne detection and can be easily implemented in any transient grating setup.

  9. Charge Carrier Dynamics of Quantum Confined Semiconductor Nanoparticles Analyzed via Transient Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thibert, Arthur Joseph, III

    Semiconductor nanoparticles are tiny crystalline structures (typically range from 1 - 100 nm) whose shape in many cases can be dictated through tailored chemical synthesis with atomic scale precision. The small size of these nanoparticles often results in quantum confinement (spatial confinement of wave functions), which imparts the ability to manipulate band-gap energies thus allowing them to be optimally engineered for different applications (i.e., photovoltaics, photocatalysis, imaging). However, charge carriers excited within these nanoparticles are often involved in many different processes: trapping, trap migration, Auger recombination, non-radiative relaxation, radiative relaxation, oxidation / reduction, or multiple exciton generation. Broadband ultrafast transient absorption laser spectroscopy is used to spectrally resolve the fate of excited charge carriers in both wavelength and time, providing insight as to what synthetic developments or operating conditions will be necessary to optimize their efficiency for certain applications. This thesis outlines the effort of resolving the dynamics of excited charge carriers for several Cd and Si based nanoparticle systems using this experimental technique. The thesis is organized into five chapters and two appendices as indicated below. Chapter 1 provides a brief introduction to the photophysics of semiconductor nanoparticles. It begins by defining what nanoparticles, semiconductors, charge carriers, and quantum confinement are. From there it details how the study of charge carrier dynamics within nanoparticles can lead to increased efficiency in applications such as photocatalysis. Finally, the experimental methodology associated with ultrafast transient absorption spectroscopy is introduced and its power in mapping charge carrier dynamics is established. Chapter 2 (JPCC, 19647, 2011) introduces the first of the studied samples: water-solubilized 2D CdSe nanoribbons (NRs), which were synthesized in the Osterloh

  10. Contrast-induced transient cortical blindness.

    PubMed

    Shah, Parth R; Yohendran, Jayshan; Parker, Geoffrey D; McCluskey, Peter J

    2013-05-01

    We present a case of transient cortical blindness secondary to contrast medium toxicity. A 58-year-old man had successful endovascular coiling of a right posterior inferior cerebellar artery aneurysm but became confused and unable to see after the procedure. His visual acuity was no light perception bilaterally. Clinically, there was no new intra-ocular pathology. An urgent non-contrast computed tomography scan of the brain showed cortical hyperdensity in both parieto-occipital cortices, consistent with contrast medium leakage through the blood-brain barrier from the coiling procedure. The man remained completely blind for 72 hours, after which his visual acuity improved gradually back to his baseline level.

  11. [Study on transient absorption spectrum of tungsten nanoparticle with HepG2 tumor cell].

    PubMed

    Cao, Lin; Shu, Xiao-Ning; Liang, Dong; Wang, Cong

    2014-07-01

    Significance of this study lies in tungsten nano materials can be used as a preliminary innovative medicines applied basic research. This paper investigated the inhibition of tungsten nanoparticles which effected on human hepatoma HepG2 cells by MTT. The authors use transient absorption spectroscopy (TAS) technology absorption and emission spectra characterization of charge transfer between nanoparticles and tumor cell. The authors discussed the role of the tungsten nanoparticles in the tumor early detection of the disease and its anti-tumor properties. In the HepG2 experiments system, 100-150 microg x mL(-1) is the best drug concentration of anti-tumor activity which recact violently within 6 hours and basically completed in 24 hours. The results showed that transient absorption spectroscopy can be used as tumor detection methods and characterization of charge transfer between nano-biosensors and tumor cells. Tungsten nanoparticles have potential applications as anticancer drugs.

  12. Transient absorption studies of vibrational relaxation and photophysics of Prussian blue and ruthenium purple nanoparticles

    NASA Astrophysics Data System (ADS)

    Weidinger, D.; Brown, D. J.; Owrutsky, J. C.

    2011-03-01

    Transient infrared and visible absorption studies have been used to characterize vibrational and electronic dynamics of Prussian blue (PB) and ruthenium purple (RP) nanoparticles produced and characterized in AOT reverse micelles. Studies include excitation and probing with both infrared (near 2000 cm-1) and visible (800 nm) pulses. From IR pump-IR probe measurements of the CN stretching bands, vibrational population lifetimes are determined to be 32 ± 4 ps for PB and 44 ± 14 ps for RP. These times are longer than those for ferrocyanide (4 ps) and ruthenocyanide (4 ps) in normal water and are closer to the times for these species in heavy water (25-30 ps) and for ferrocyanide in formamide (43 ps). The PB and RP lifetimes are also longer than those (<15 ps) previously measured for CN stretching bands following intervalence excitation and back-electron transfer (BET) for dinuclear mixed-valence compounds containing Fe, Ru, and Os in heavy water and formamide [A. V. Tivansky, C. F. Wang, and G. C. Walker, J. Phys. Chem. A 107, 9051 (2003)]. In 800 nm pump-IR probe experiments on RP and PB, transient IR spectra and decay curves are similar to those with IR excitation; a ground state bleach and a red shifted (by ˜40 cm-1) excited state decay are observed. These results for the visible pumping are consistent with rapid (<1 ps) BET resulting in population in the ground electronic state with vibrational excitation in the CN mode. In addition, transient absorption studies were performed for PB and RP probing with visible light using both visible and IR excitation. The early time response for the 800 nm pump-800 nm probe of PB exhibits an instrument-limited, subpicosecond bleach followed by an absorption, which is consistent with the previously reported results [D. C. Arnett, P. Vohringer, and N. F. Scherer, J. Am. Chem. Soc. 117, 12262 (1995)]. The absorption exhibits a biexponential decay with decay times of 9 and 185 ps, which could have been attributed to the CN band

  13. Transient nuclear Prospero induces neural progenitor quiescence

    PubMed Central

    Lai, Sen-Lin; Doe, Chris Q

    2014-01-01

    Stem cells can self-renew, differentiate, or enter quiescence. Understanding how stem cells switch between these states is highly relevant for stem cell-based therapeutics. Drosophila neural progenitors (neuroblasts) have been an excellent model for studying self-renewal and differentiation, but quiescence remains poorly understood. In this study, we show that when neuroblasts enter quiescence, the differentiation factor Prospero is transiently detected in the neuroblast nucleus, followed by the establishment of a unique molecular profile lacking most progenitor and differentiation markers. The pulse of low level nuclear Prospero precedes entry into neuroblast quiescence even when the timing of quiescence is advanced or delayed by changing temporal identity factors. Furthermore, loss of Prospero prevents entry into quiescence, whereas a pulse of low level nuclear Prospero can drive proliferating larval neuroblasts into quiescence. We propose that Prospero levels distinguish three progenitor fates: absent for self-renewal, low for quiescence, and high for differentiation. DOI: http://dx.doi.org/10.7554/eLife.03363.001 PMID:25354199

  14. Unusual transient absorption dynamics of silver nanoparticles in solutions of carboxylated amine complexons

    NASA Astrophysics Data System (ADS)

    Shevchenko, G. P.; Zhuravkov, V. A.; Tretyak, E. V.; Tikhomirov, S. A.; Buganov, O. V.; Ponyavina, A. N.; Pham, Hong Minh; Do, Hoang Tung; Duong Pham, Van; Nguyen, Dai Hung

    2016-09-01

    We present the results of research on fast relaxation dynamics in the electronic excitation of silver nanoparticles synthesized in the presence of carboxylated amine complexons (NTA, Na2EDTA, DTPA) without any reductant or polymeric stabilizer. Unusual transient absorption dynamics in these objects after femtosecond laser irradiation was found, manifesting as the appearance of an additional long-lived bleaching band. The effect may be assigned to the inhomogeneous and porous shell of silver nanoparticles synthesized by such a procedure, as the consequence of a partial fragmentation of this shell due to heating under femtosecond laser excitation of plasmonic nanoparticles and subsequent electron-phonon energy relaxation.

  15. Nanoparticle-induced pulmonary toxicity.

    PubMed

    Li, Jasmine Jia'en; Muralikrishnan, Sindu; Ng, Cheng-Teng; Yung, Lin-Yue Lanry; Bay, Boon-Huat

    2010-09-01

    In recent decades, advances in nanotechnology engineering have given rise to the rapid development of many novel applications in the biomedical field. However, studies into the health and safety of these nanomaterials are still lacking. The main concerns are the adverse effects to health caused by acute or chronic exposure to nanoparticles (NPs), especially in the workplace environment. The lung is one of the main routes of entry for NPs into the body and, hence, a likely site for accumulation of NPs. Once NPs enter the interstitial air spaces and are quickly taken up by alveolar cells, they are likely to induce toxic effects. In this review, we highlight the different aspects of lung toxicity resulting from NP exposure, such as generation of oxidative stress, DNA damage and inflammation leading to fibrosis and pneumoconiosis, and the underlying mechanisms causing pulmonary toxicity.

  16. Acute transient hemiparesis induced by lightning strike.

    PubMed

    Rahmani, Seyed Hesam; Faridaalaee, Gholamreza; Jahangard, Samira

    2015-07-01

    According to data from the National Oceanic and Atmospheric Administration,in the years from 1959 to 1994, lightning was responsible for more than 3000 deaths and nearly 10,000 casualties. The most important characteristic features of lightning injuries are multisystem involvement and widely variable severity. Lightning strikes are primarily a neurologic injury that affects all 3 components of the nervous system: central, autonomic,and peripheral. Neurologic complications of lightning strikes vary from transient benign symptoms to permanent disability. Many patients experience a temporary paralysis called keraunoparalysis. Here we reported a 22-year-old mountaineer man with complaining of left sided hemiparesis after being hit by a lightning strike in the mountain 3 hours ago. There was no loss of consciousness at hitting time. On arrival the patient was alert, awake and hemodynamically stable. In neurologic examination cranial nerves were intact, left sided upper and lower extremity muscle force was I/V with a combination of complete sensory loss, and right-sided muscle force and sensory examination were normal. There is not any evidence of significant vascular impairment in the affected extremities. Brain MRI and CT scan and cervical MRI were normal. During 2 days of admission, with intravenous hydration, heparin 5000 unit SC q12hr and physical therapy of the affected limbs, motor and sensory function improved and was normal except mild paresthesia. He was discharged 1 day later for outpatient follow up while vitamin B1 100mg orally was prescribed.Paresthesia improved after 3 days without further sequels.

  17. Microscopic heat pulses induce contraction of cardiomyocytes without calcium transients

    SciTech Connect

    Oyama, Kotaro; Mizuno, Akari; Shintani, Seine A.; Itoh, Hideki; Serizawa, Takahiro; Fukuda, Norio; Suzuki, Madoka

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Infra-red laser beam generates microscopic heat pulses. Black-Right-Pointing-Pointer Heat pulses induce contraction of cardiomyocytes. Black-Right-Pointing-Pointer Ca{sup 2+} transients during the contraction were not detected. Black-Right-Pointing-Pointer Skinned cardiomyocytes in free Ca{sup 2+} solution also contracted. Black-Right-Pointing-Pointer Heat pulses regulated the contractions without Ca{sup 2+} dynamics. -- Abstract: It was recently demonstrated that laser irradiation can control the beating of cardiomyocytes and hearts, however, the precise mechanism remains to be clarified. Among the effects induced by laser irradiation on biological tissues, temperature change is one possible effect which can alter physiological functions. Therefore, we investigated the mechanism by which heat pulses, produced by infra-red laser light under an optical microscope, induce contractions of cardiomyocytes. Here we show that microscopic heat pulses induce contraction of rat adult cardiomyocytes. The temperature increase, {Delta}T, required for inducing contraction of cardiomyocytes was dependent upon the ambient temperature; that is, {Delta}T at physiological temperature was lower than that at room temperature. Ca{sup 2+} transients, which are usually coupled to contraction, were not detected. We confirmed that the contractions of skinned cardiomyocytes were induced by the heat pulses even in free Ca{sup 2+} solution. This heat pulse-induced Ca{sup 2+}-decoupled contraction technique has the potential to stimulate heart and skeletal muscles in a manner different from the conventional electrical stimulations.

  18. Molecular-level mechanisms of nanoparticle detachment in laser-induced plasma shock waves

    SciTech Connect

    Zhou Dong; Cetinkaya, Cetin

    2006-04-24

    Detachment and detachment mechanisms of nanoparticles from flat surfaces subjected to shock waves are investigated by employing molecular gas dynamic simulations using the direct simulation Monte Carlo method and experimental transient pressure data. Two mechanisms for nanoparticle detachment based on rolling moment resistance of the adhesion bond and the elastic restitution effect are introduced. As a result of present simulations, it is computationally demonstrated that the pulsed laser-induced shock waves can generate sufficient rolling moments to detach sub-100-nm particles and initiate removal. The transient moment exerted on a 60 nm polystyrene latex particle on a silicon substrate is presented and discussed.

  19. An Unexpected Transient Breakdown of the Blood Brain Barrier Triggers Passage of Large Intravenously Administered Nanoparticles

    NASA Astrophysics Data System (ADS)

    Smith, Nicole M.; Gachulincova, Ivana; Ho, Diwei; Bailey, Charlotte; Bartlett, Carole A.; Norret, Marck; Murphy, John; Buckley, Alysia; Rigby, Paul J.; House, Michael J.; St. Pierre, Timothy; Fitzgerald, Melinda; Iyer, K. Swaminathan; Dunlop, Sarah A.

    2016-03-01

    The highly restrictive blood-brain barrier (BBB) plays a critically important role in maintaining brain homeostasis and is pivotal for proper neuronal function. The BBB is currently considered the main limiting factor restricting the passage of large (up to 200 nm) intravenously administered nanoparticles to the brain. Breakdown of the barrier occurs as a consequence of cerebrovascular diseases and traumatic brain injury. In this article, we report that remote injuries in the CNS are also associated with BBB dysfunction. In particular, we show that a focal partial transection of the optic nerve triggers a previously unknown transient opening of the mammalian BBB that occurs in the visual centres. Importantly, we demonstrate that this transient BBB breakdown results in a dramatic change in the biodistribution of intravenously administered large polymeric nanoparticles which were previously deemed as BBB-impermeable.

  20. Radio Transients from Accretion-induced Collapse of White Dwarfs

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.

    2016-10-01

    We investigate observational properties of accretion-induced collapse (AIC) of white dwarfs (WDs) in radio frequencies. If AIC is triggered by accretion from a companion star, a dense circumstellar medium can be formed around the progenitor system. Then, the ejecta from AIC collide with the dense circumstellar medium, creating a strong shock. The strong shock can produce synchrotron emission that can be observed in radio frequencies. Even if AIC occurs as a result of WD mergers, we argue that AIC may cause fast radio bursts (FRBs) if a certain condition is satisfied. If AIC forms neutron stars (NSs) that are so massive that rotation is required to support themselves (i.e., supramassive NSs), the supramassive NSs may immediately lose their rotational energy by the r-mode instability and collapse to black holes. If the collapsing supramassive NSs are strongly magnetized, they may emit FRBs, as previously proposed. The AIC radio transients from single-degenerate systems may be detected in future radio transient surveys like the Very Large Array Sky Survey or the Square Kilometer Array transient survey. Because AIC has been proposed as a source of gravitational waves (GWs), GWs from AIC may be accompanied by radio-bright transients that can be used to confirm the AIC origin of observed GWs.

  1. Magnetic induced heating of nanoparticle solutions

    SciTech Connect

    Murph, S. Hunyadi; Brown, M.; Coopersmith, K.; Fulmer, S.; Sessions, H.; Ali, M.

    2016-12-02

    Magnetic induced heating of nanoparticles (NP) provides a useful advantage for many energy transfer applications. This study aims to gain an understanding of the key parameters responsible for maximizing the energy transfer leading to nanoparticle heating through the use of simulations and experimental results. It was found that magnetic field strength, NP concentration, NP composition, and coil size can be controlled to generate accurate temperature profiles in NP aqueous solutions.

  2. Transient light-induced intracellular oxidation revealed by redox biosensor

    SciTech Connect

    Kolossov, Vladimir L.; Beaudoin, Jessica N.; Hanafin, William P.; DiLiberto, Stephen J.; Kenis, Paul J.A.; Rex Gaskins, H.

    2013-10-04

    Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition.

  3. HEMP-induced transients in electric power substations

    SciTech Connect

    Wiggins, C.M.; Thomas, D.E.; Salas, T.M. )

    1992-02-01

    A nuclear detonation in or above the earth's atmosphere produces an intense electromagnetic pulse (EMP). A large portion of the EMP electromagnetic energy is within the RF spectrum. A detonation at high altitudes above 40 km produces an EMP called high-altitude EMP (HEMP). HEMP is a steep-front short duration transient with a rise time on the order of a few nanoseconds which decays to near zero in less than a microsecond. A single high-altitude burst can subject much of the continental United States to intense HEMP electric fields on the order of tens of kilovolts per meter. The intense transient HEMP will induce fast transients in high-voltage transmission lines and bus structures, instrumentation cables, and control wires in power transmission and distribution (T D) substations. A system of traveling wave coupling models for a 500 kV substation, including models for the high voltage primary bus, components (circuit breakers, disconnect switches, power transformers, and current and voltage instrument transformers), low voltage control wiring circuits, and a number of conducted and radiated interference coupling modes, had been developed earlier by EPRI. These EPRI served as the baseline for the present HEMP coupling investigations. The HEMP effects on protective relays were assessed for a nominal HEMP environment using several new field coupling models merged with the switching transient data. It is found that a representative solid state relay is unlikely to be damaged or to misoperate by the nominal HEMP threat with a peak field strength of 50 kV/m. However, it is possible for both DC control wires to flash over to ground simultaneously, causing fuses to blow and placing the relay in an inoperative state.

  4. HEMP-induced transients in electric power substations. Final report

    SciTech Connect

    Wiggins, C.M.; Thomas, D.E.; Salas, T.M.

    1992-02-01

    A nuclear detonation in or above the earth`s atmosphere produces an intense electromagnetic pulse (EMP). A large portion of the EMP electromagnetic energy is within the RF spectrum. A detonation at high altitudes above 40 km produces an EMP called high-altitude EMP (HEMP). HEMP is a steep-front short duration transient with a rise time on the order of a few nanoseconds which decays to near zero in less than a microsecond. A single high-altitude burst can subject much of the continental United States to intense HEMP electric fields on the order of tens of kilovolts per meter. The intense transient HEMP will induce fast transients in high-voltage transmission lines and bus structures, instrumentation cables, and control wires in power transmission and distribution (T & D) substations. A system of traveling wave coupling models for a 500 kV substation, including models for the high voltage primary bus, components (circuit breakers, disconnect switches, power transformers, and current and voltage instrument transformers), low voltage control wiring circuits, and a number of conducted and radiated interference coupling modes, had been developed earlier by EPRI. These EPRI served as the baseline for the present HEMP coupling investigations. The HEMP effects on protective relays were assessed for a nominal HEMP environment using several new field coupling models merged with the switching transient data. It is found that a representative solid state relay is unlikely to be damaged or to misoperate by the nominal HEMP threat with a peak field strength of 50 kV/m. However, it is possible for both DC control wires to flash over to ground simultaneously, causing fuses to blow and placing the relay in an inoperative state.

  5. Temperature-induced transient noise of pyroelectric thermal detector

    NASA Astrophysics Data System (ADS)

    Lee, Muno; Bae, Seong-Ho

    2000-11-01

    An analysis of temperature-induced transient noise for a thermal detector prepared with Pb(Zr,Ti)O3-Pb(Sb0.5Nb0.5)O3 (PZT-PSN) pyroelectric ceramics as the sensing element is conducted by measuring its oven noise as a function of the junction field-effect transistor (JFET) characteristics, gate resistance, low-temperature heat treatment, chemical composition and the grain size of the pyroelectric ceramic. Pyroelectric wafers are prepared by the mixed oxide technique, and thermal sensors are fabricated with a PZT-PSN ceramic wafer, JFET, chip-type gate resistor, alumina PCB (printed circuit board) and a TO- 5 package with antireflective (AR)-coated Si window. Thermal detector noise depends on the chemical composition of the pyroelectric sensing element. The temperature-induced transient JFET noise varies with its characteristics and gate resistance and is reduced by connecting a pyroelectric sensing element with high capacitance. The pyroelectric ceramic sensing element generates burst noise in the region from 7 to -10 degree(s)C during cooling, which is remarkably reduced by reducing the grain size of the pyroelectric ceramic and/or by cyclic heat treatment at a low temperature. Thus, burst noise as a strong relationship with the elastic energies within the ceramic sensing element and the bonding material between the sensing wafer and the PCB, originating in the different thermal expansion between pyroelectric sensing wafer and alumina PCB.

  6. Radiation-induced transient darkening of optically transparent polymers

    SciTech Connect

    Downey, S.W.; Builta, L.A.; Carlson, R.L.; Czuchlewski, S.J.; Moir, D.C.

    1986-11-15

    Results are presented for the radiation-induced transient darkening of thin organic polymer films normally used as Cerenkov light emissions sources. The radiation source is a 27-MeV, 10-..mu..C, 200-ns electron beam generated by the PHERMEX accelerator. The typical dose for a single pulse is 5 Mrad. At this dose, the broadband time-resolved percent transmission above 520 nm was measured for four common polymers: polyimide (Kapton-H), polyethylene terephthalate (Mylar), cellulose acetate, and high-density polyethylene. Kapton was found to darken the most and polyethylene darkened the least. The recovery time to normal transmission for Kapton was found to be greater than 10--20 ..mu..s. The radiation-induced attenuation coefficient is shown to depend on electronic band energy separation. The results show that Kapton is not the material of choice for a Cerenkov light source.

  7. Visualizing interfacial charge transfer in dye sensitized nanoparticles using x-ray transient absorption spectroscopy.

    SciTech Connect

    Zhang, X. Y.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X.

    2011-01-01

    A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru-N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

  8. Influence of laser parameters on nanoparticle-induced membrane permeabilization

    NASA Astrophysics Data System (ADS)

    Yao, Cuiping; Qu, Xiaochao; Zhang, Zhenxi; Hüttmann, Gereon; Rahmanzadeh, Ramtin

    2009-09-01

    Light-absorbing nanoparticles that are heated by short laser pulses can transiently increase membrane permeability. We evaluate the membrane permeability by flow cytometry assaying of propidium iodide and fluorescein isothiocyanate dextran (FITC-D) using different laser sources. The dependence of the transfection efficiency on laser parameters such as pulse duration, irradiant exposure, and irradiation mode is investigated. For nano- and also picosecond irradiation, we show a parameter range where a reliable membrane permeabilization is achieved for 10-kDa FITC-D. Fluorescent labeled antibodies are able to penetrate living cells that are permeabilized using these parameters. More than 50% of the cells are stained positive for a 150-kDa IgG antibody. These results suggest that the laser-induced permeabilization approach constitutes a promising tool for targeted delivery of larger exogenous molecules into living cells.

  9. FDTD modeling of induced polarization phenomena in transient electromagnetics

    NASA Astrophysics Data System (ADS)

    Commer, Michael; Petrov, Petr V.; Newman, Gregory A.

    2017-01-01

    The finite-difference time-domain scheme is augmented in order to treat the modeling of transient electromagnetic signals containing induced polarization effects from three-dimensional distributions of polarizable media. Compared to the non-dispersive problem, the discrete dispersive Maxwell system contains costly convolution operators. Key components to our solution for highly digitized model meshes are Debye decomposition and composite memory variables. We revert to the popular Cole-Cole model of dispersion to describe the frequency-dependent behaviour of electrical conductivity. Its inversely Laplace-transformed Debye decomposition results in a series of time convolutions between electric field and exponential decay functions, with the latter reflecting each Debye constituents' individual relaxation time. These function types in the discrete-time convolution allow for their substitution by memory variables, annihilating the otherwise prohibitive computing demands. Numerical examples demonstrate the efficiency and practicality of our algorithm.

  10. Workshop on Transient Induced Insulator Flashover in Vacuum

    NASA Astrophysics Data System (ADS)

    A workshop to discuss the state-of-the-art in transient induced insulator flashover in vacuum was convened at the Pleasanton Hilton at the Club Hotel on August 24-25, 1988. The workshop was attended by 39 participants. Flashover of vacuum-insulator surfaces is the limiting factor in virtually all well designed high voltage, pulsed systems where such interfaces are needed. They are critical to many LLNL present and future applications. The workshop participants attempted via presentations and lively discussions to summarize the state-of-the-art in the field and to outline the critical research topics which could lead to advances in understanding and applications. Several new results were presented at the workshop and an intense discussion session resulted in the formulation of a set of research recommendations and priorities.

  11. Laser-induced stress transients: applications for molecular delivery

    NASA Astrophysics Data System (ADS)

    Flotte, Thomas J.; Lee, Shun; Zhang, Hong; McAuliffe, Daniel J.; Douki, Tina; Doukas, Apostolos G.

    1995-05-01

    Lasers can be used to enhance the delivery of a number of molecules. Other investigators have demonstrated local release of molecules from liposomes following laser irradiation, microbeam disruption of the cell membrane to increase cell transport, microbeam ablation of the zona pellucida surrounding the ovum to increase the chances of fertilization, and increased transcutaneous transport following ablation of the stratum corneum. Our experiments have shown that laser-induced stress transients can be utilized as a vector for intracellular delivery of molecules that may or may not normally cross the cell membrane. These two conditions have been tested with Photofrin and DNA. This technology may have applications in cell and molecular biology, cancer therapy, gene therapy, and others.

  12. Workshop on transient induced insulator flashover in vacuum

    SciTech Connect

    Not Available

    1988-01-01

    A workshop to discuss the state-of-the-art in transient induced insulator flashover in vacuum was convened at the Pleasanton Hilton at the Club Hotel on August 24-25, 1988. The workshop was attended by 39 participants. Flashover of vacuum-insulator surfaces is the limiting factor in virtually all well designed high voltage, pulsed systems where such interfaces are needed. They are critical to many LLNL present and future applications. The workshop participants attempted via presentations and lively discussions to summarize the state-of-the-art in the field and to outline the critical research topics which could lead to advances in understanding and applications. Several new results were presented at the workshop and an intense discussion session resulted in the formulation of a set of research recommendations and priorities.

  13. Pacemaker-Induced Transient Asynchrony Suppresses Heart Failure Progression

    PubMed Central

    Kirk, Jonathan A.; Chakir, Khalid; Lee, Kyoung Hwan; Karst, Edward; Holewinski, Ronald J.; Pironti, Gianluigi; Tunin, Richard S.; Pozios, Iraklis; Abraham, Theodore P.; de Tombe, Pieter; Rockman, Howard A.; Van Eyk, Jennifer E.; Craig, Roger; Farazi, Taraneh G.; Kass, David A.

    2016-01-01

    Uncoordinated contraction from electromechanical delay worsens heart failure pathophysiology and prognosis, but restoring coordination with bi-ventricular pacing, known as cardiac resynchronization therapy (CRT) improves both. Not every patient, however, qualifies for CRT. Here we show that heart failure with synchronous contraction is improved by inducing dyssynchrony for 6 hours daily by right-ventricular pacing using an intracardiac pacing device, in a process we call pacemaker-induced transient asynchrony (PITA). In dogs with heart failure induced by 6 weeks of atrial tachypacing, PITA (starting on week 3) suppressed progressive cardiac dilation as well as chamber and myocyte dysfunction. PITA enhanced β-adrenergic responsiveness in vivo and normalized it in myocytes. Myofilament calcium response declined in dogs with synchronous heart failure, which was accompanied by sarcomere disarray and generation of myofibers with severely reduced function, and these changes were absent in PITA-treated hearts. The benefits of PITA were not replicated when the same number of RV-paced beats was randomly distributed throughout the day, indicating that continuity of dyssynchrony exposure is necessary to trigger the beneficial biological response upon resynchronization. These results suggest PITA could bring the benefits of CRT to the many heart failure patients with synchronous contraction that are not CRT candidates. PMID:26702095

  14. Transient loading of CD34+ hematopoietic progenitor cells with polystyrene nanoparticles

    PubMed Central

    Deville, Sarah; Hadiwikarta, Wahyu Wijaya; Smisdom, Nick; Wathiong, Bart; Ameloot, Marcel; Nelissen, Inge; Hooyberghs, Jef

    2017-01-01

    CD34+ hematopoietic progenitor cells (HPCs) offer great opportunities to develop new treatments for numerous malignant and non-malignant diseases. Nanoparticle (NP)-based strategies can further enhance this potential, and therefore a thorough understanding of the loading behavior of HPCs towards NPs is essential for a successful application. The present study focusses on the interaction kinetics of 40 nm sized carboxylated polystyrene (PS) NPs with HPCs. Interestingly, a transient association of the NPs with HPCs is observed, reaching a maximum within 1 hour and declining afterwards. This behavior is not seen in dendritic cells (CD34-DCs) differentiated from HPCs, which display a monotonic increase in NP load. We demonstrate that this transient interaction requires an energy-dependent cellular process, suggesting active loading and release of NPs by HPCs. This novel observation offers a unique approach to transiently equip HPCs. A simple theoretical approach modeling the kinetics of NP loading and release is presented, contributing to a framework of describing this phenomenon. PMID:28138242

  15. Ultrafast transient absorption studies of hematite nanoparticles: the effect of particle shape on exciton dynamics.

    PubMed

    Fitzmorris, Bob C; Patete, Jonathan M; Smith, Jacqueline; Mascorro, Xiomara; Adams, Staci; Wong, Stanislaus S; Zhang, Jin Z

    2013-10-01

    Much progress has been made in using hematite (α-Fe2 O3 ) as a potentially practical and sustainable material for applications such as solar-energy conversion and photoelectrochemical (PEC) water splitting; however, recent studies have shown that the performance can be limited by a very short charge-carrier diffusion length or exciton lifetime. In this study, we performed ultrafast studies on hematite nanoparticles of different shapes to determine the possible influence of particle shape on the exciton dynamics. Nanorice, multifaceted spheroidal nanoparticles, faceted nanocubes, and faceted nanorhombohedra were synthesized and characterized by using SEM and XRD techniques. Their exciton dynamics were investigated by using femtosecond transient absorption (TA) spectroscopy. Although the TA spectral features differ for the four samples studied, their decay profiles are similar, which can be fitted with time constants of 1-3 ps, approximately 25 ps, and a slow nanosecond component extending beyond the experimental time window that was measured (2 ns). The results indicate that the overall exciton lifetime is weakly dependent on the shape of the hematite nanoparticles, even though the overall optical absorption and scattering are influenced by the particle shape. This study suggests that other strategies need to be developed to increase the exciton lifetime or to lengthen the exciton diffusion length in hematite nanostructures.

  16. Transient arrest of psychogenic tremor induced by contralateral ballistic movements.

    PubMed

    Kumru, Hatice; Valls-Solé, Josep; Valldeoriola, Francesc; Marti, Maria José; Sanegre, Maria Teresa; Tolosa, Eduardo

    2004-11-11

    One of the clinical characteristics of psychogenic tremors (PT) is the disruption or transient cessation of tremor with distractive manoeuvres, including those involving the performance of voluntary movements with the contralateral hand. Seven patients with PT, 11 patients with Parkinson's disease (PD), 10 patients with essential tremor (ET) and 10 normal volunteers mimicking tremor (NV) were requested to perform a fast unilateral wrist movement to close a switch, at the perception of a visual cue, either at rest or during maintenance of a posture. We measured the time-locked changes in frequency and amplitude occurring in tremor oscillations of the contralateral hand. The reaction time task induced a significant reduction in amplitude or cessation of contralateral tremor oscillations in PT and NV, but not in PD and ET. The effect occurred with a delay with respect to the onset of the contralateral movement without significant differences in PT versus NV (p > 0.05). The physiological mechanisms accounting for the effect seen on tremor of NV and PT may involve the interhemispheric inhibition that accompanies the execution of a unilateral motor task. Tremor circuits in patients with PD and ET may be impervious to these inhibitory commands. The documentation and quantitation of the effects of a ballistic movement on contralateral rhythmic activity are of clinical relevance for the identification of patients with PT.

  17. Effects of electrode geometry on transient plasma induced ignition

    NASA Astrophysics Data System (ADS)

    Shukla, B.; Gururajan, V.; Eisazadeh-Far, K.; Windom, B.; Singleton, D.; Gundersen, M. A.; Egolfopoulos, F. N.

    2013-05-01

    Achieving effective ignition of reacting mixtures using nanosecond pulsed discharge non-equilibrium transient plasma (TP), requires that the effects of several experimental parameters be quantified and understood. Among them are the electrode geometry, the discharge location especially in non-premixed systems, and the relative ignition performance by spark and TP under the same experimental conditions. In the present investigation, such issues were addressed experimentally using a cylindrical constant volume combustion chamber and a counterflow flame configuration coupled with optical shadowgraph that enables observation of how and where the ignition process starts. Results were obtained under atmospheric pressure and showed that the electrode geometry has a notable influence on ignition, with the needle-to-semicircle exhibiting the best ignition performance. Furthermore, it was determined that under non-premixed conditions discharging TP in the reactants mixing layer was most effective in achieving ignition. It was also determined that in the cases considered, the TP induced ignition initiates from the needle head where the electric field and electron densities are the highest. In the case of a spark, however, ignition was found to initiate always from the hot region between the two electrodes. Comparison of spark and TP discharges in only air (i.e. without fuel) and ignition phenomena induced by them also suggest that in the case of TP ignition is at least partly non-thermal and instead driven by the production of active species. Finally, it was determined that single pulsed TP discharges are sufficient to ignite both premixed and non-premixed flames of a variety of fuels ranging from hydrogen to heavy fuels including F-76 diesel and IFO380 bunker fuel even at room temperature.

  18. Analysis and Simulations of Space Radiation Induced Single Event Transients

    NASA Astrophysics Data System (ADS)

    Perez, Reinaldo

    2016-05-01

    Spacecraft electronics are affected by the space radiation environment. Among the different types of radiation effects that can affect spacecraft electronics is the single event transients. The space environment is responsible for many of the single event transients which can upset the performance of the spacecraft avionics hardware. In this paper we first explore the origins of single event transients, then explore the modeling of a single event transient in digital and analog circuit. The paper also addresses the concept of crosstalk that could develop among digital circuits in the present of a SET event. The paper ends with a brief discussion of SET hardening. The goal of the paper is to provide methodologies for assessing single event transients and their effects so that spacecraft avionics engineers can develop either hardware or software countermeasures in their designs.

  19. Laser-Induced Transfer of Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Arseniy I.; Koch, Jürgen; Chichkov, Boris N.

    2010-10-01

    A novel approach for the fabrication of metallic micro- and nanostructures based on femtosecond laser-induced transfer of metallic nanodroplets is developed. The size of the transferred droplets depends on the volume of laser-molten metal and can be varied by changing the laser beam focus on the sample surface and the metal film thickness. Controllable fabrication of high quality spherical gold micro- and nanoparticles with sizes between 170 nm and 1500 nm is realized. Fabrication of miscellaneous structures consisting of gold particles as elementary building blocks is demonstrated.

  20. Transient studies of G-induced capillary dryout and rewet

    NASA Technical Reports Server (NTRS)

    Reagan, M. K.; Bowman, W. J.

    1995-01-01

    A transient, one-dimensional numerical code is developed to model the liquid motion in an axial groove with square cross section. Axial variation in liquid level, shear stress and heat transfer between the groove wall and the liquid, evaporation and transient body forces are accounted for in the model. Dryout and rewet of the groove are allowed; the front location is determined numerically using conservation of mass and linear extrapolation. Several numerical test results are presented and discussed.

  1. Copper Nanoparticle Induced Cytotoxicity to Nitrifying Bacteria ...

    EPA Pesticide Factsheets

    With the inclusion of engineered nanomaterials in industrial processes and consumer products, wastewater treatments plants (WWTPs) will serve as a major sink for these emerging contaminants. Previous research has demonstrated that nanomaterials are potentially toxic to microbial communities utilized in biological wastewater treatment (BWT). Copper-based nanoparticles (CuNPs) are of particular interest based on their increasing use in wood treatment, paints, household products, coatings, and byproducts of semiconductor manufacturing. A critical step in BWT is nutrient removal via denitrification. This study examined the potential toxicity of bare and polyvinylpyrrolidone (PVP) coated CuO, and Cu2O nanoparticles, as well as Cu ions to microbial communities responsible for nitrogen removal in BWT. Inhibition was inferred from changes to the specific oxygen uptake rate (sOUR) in the absence and presence of Cu ions and CuNPs. X-ray absorption fine structure spectroscopy, with Linear Combination Fitting (LCF), was utilized to track changes to Cu speciation throughout exposure. Results indicate that the dissolution of Cu ions from CuNPs drive microbial inhibition. The presence of a PVP coating on CuNPs has little effect on inhibition. LCF fitting of the biomass combined with metal partitioning analysis supports the current hypothesis that Cu-induced cytotoxicity is primarily caused by reactive oxygen species formed from ionic Cu in solution via catalytic reaction inter

  2. Transient corneal opacification induced by cold in Raynaud's disease.

    PubMed

    McWhae, J A; Andrews, D M

    1991-05-01

    A 48-year-old man presented with longstanding complaints of transient blurring of vision on exposure to cold temperatures. A review of family history was noteworthy in that two of the patient's four sons and the patient's brother had similar complaints. All affected individuals had Raynaud's disease. Results of ophthalmic evaluation showed transient corneal opacities. Slit-lamp video photography under cold stress demonstrated conjunctival vascular changes consistent with Raynaud's phenomenon. An extensive work-up for systemic disease was otherwise negative. To the best of the authors' knowledge, anterior segment changes have not been described previously in idiopathic Raynaud's disease.

  3. Marek's disease virus induced transient paralysis--a closer look

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marek’s Disease (MD) is a lymphoproliferative disease of domestic chickens caused by a highly cell-associated alpha herpesvirus, Marek’s disease virus (MDV). Clinical signs of MD include depression, crippling, weight loss, and transient paralysis (TP). TP is a disease of the central nervous system...

  4. ELM-induced transient tungsten melting in the JET divertor

    NASA Astrophysics Data System (ADS)

    Coenen, J. W.; Arnoux, G.; Bazylev, B.; Matthews, G. F.; Autricque, A.; Balboa, I.; Clever, M.; Dejarnac, R.; Coffey, I.; Corre, Y.; Devaux, S.; Frassinetti, L.; Gauthier, E.; Horacek, J.; Jachmich, S.; Komm, M.; Knaup, M.; Krieger, K.; Marsen, S.; Meigs, A.; Mertens, Ph.; Pitts, R. A.; Puetterich, T.; Rack, M.; Stamp, M.; Sergienko, G.; Tamain, P.; Thompson, V.; Contributors, JET-EFDA

    2015-02-01

    The original goals of the JET ITER-like wall included the study of the impact of an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek et al 2013 Nucl. Fusion 53 083023). ITER has recently decided to install a full-tungsten (W) divertor from the start of operations. One of the key inputs required in support of this decision was the study of the possibility of W melting and melt splashing during transients. Damage of this type can lead to modifications of surface topology which could lead to higher disruption frequency or compromise subsequent plasma operation. Although every effort will be made to avoid leading edges, ITER plasma stored energies are sufficient that transients can drive shallow melting on the top surfaces of components. JET is able to produce ELMs large enough to allow access to transient melting in a regime of relevance to ITER. Transient W melt experiments were performed in JET using a dedicated divertor module and a sequence of IP = 3.0 MA/BT = 2.9 T H-mode pulses with an input power of PIN = 23 MW, a stored energy of ˜6 MJ and regular type I ELMs at ΔWELM = 0.3 MJ and fELM ˜ 30 Hz. By moving the outer strike point onto a dedicated leading edge in the W divertor the base temperature was raised within ˜1 s to a level allowing transient, ELM-driven melting during the subsequent 0.5 s. Such ELMs (δW ˜ 300 kJ per ELM) are comparable to mitigated ELMs expected in ITER (Pitts et al 2011 J. Nucl. Mater. 415 (Suppl.) S957-64). Although significant material losses in terms of ejections into the plasma were not observed, there is indirect evidence that some small droplets (˜80 µm) were released. Almost 1 mm (˜6 mm3) of W was moved by ˜150 ELMs within 7 subsequent discharges. The impact on the main plasma parameters was minor and no disruptions occurred. The W-melt gradually moved along the leading edge towards the high-field side, driven by j × B forces. The evaporation rate determined

  5. Analyte-induced spectral filtering in femtosecond transient absorption spectroscopy

    DOE PAGES

    Abraham, Baxter; Nieto-Pescador, Jesus; Gundlach, Lars

    2017-03-06

    Here, we discuss the influence of spectral filtering by samples in femtosecond transient absorption measurements. Commercial instruments for transient absorption spectroscopy (TA) have become increasingly available to scientists in recent years and TA is becoming an established technique to measure the dynamics of photoexcited systems. Furthermore, we show that absorption of the excitation pulse by the sample can severely alter the spectrum and consequently the temporal pulse shape. This “spectral self-filtering” effect can lead to systematic errors and misinterpretation of data, most notably in concentration dependent measurements. Finally, the combination of narrow absorption peaks in the sample with ultrafast broadbandmore » excitation pulses is especially prone to this effect.« less

  6. Coherence-population-trapping transients induced by an ac magnetic field

    NASA Astrophysics Data System (ADS)

    Margalit, L.; Rosenbluh, M.; Wilson-Gordon, A. D.

    2012-06-01

    Coherent-population-trapping transients induced by an ac magnetic field are investigated theoretically for a realistic three-level Λ system in the D1 line of 87Rb. The contributions to the transient probe absorption from the various subsystems that compose the realistic atomic system are examined and the absorption of each Λ subsystem is compared to that of a simple Λ system. The population redistribution due to optical pumping is shown to be the dominant cause of the difference between the contributions of the various subsystems to the oscillatory character of the probe absorption. We also discuss the series of transients that reappear every half-cycle time of a modulated magnetic field when the system is in two-photon resonance, and we study the transient behavior as a function of the probe detuning. The effect of a buffer gas on the amplitude and shape of the transients is considered.

  7. Fluid shear stress induces calcium transients in osteoblasts through depolarization of osteoblastic membrane.

    PubMed

    Sun, Junqing; Liu, Xifang; Tong, Jie; Sun, Lijun; Xu, Hao; Shi, Liang; Zhang, Jianbao

    2014-12-18

    Intracellular calcium transient ([Ca(2+)]i transient) induced by fluid shear stress (FSS) plays an important role in osteoblastic mechanotransduction. Changes of membrane potential usually affect [Ca(2+)]i level. Here, we sought to determine whether there was a relationship between membrane potential and FSS-induced [Ca(2+)]i transient in osteoblasts. Fluorescent dyes DiBAC4(3) and fura-2AM were respectively used to detect membrane potential and [Ca(2+)]i. Our results showed that FSS firstly induced depolarization of membrane potential and then a transient rising of [Ca(2+)]i in osteoblasts. There was a same threshold for FSS to induce depolarization of membrane potential and [Ca(2+)]i transients. Replacing extracellular Na(+) with tetraethylammonium or blocking stretch-activated channels (SACs) with gadolinium both effectively inhibited FSS-induced membrane depolarization and [Ca(2+)]i transients. However, voltage-activated K(+) channel inhibitor, 4-Aminopyridine, did not affect these responses. Removing extracellular Ca(2+) or blocking of L-type voltage-sensitive Ca(2+) channels (L-VSCCs) with nifedipine inhibited FSS-induced [Ca(2+)]i transients in osteoblasts too. Quantifying membrane potential with patch clamp showed that the resting potential of osteoblasts was -43.3mV and the depolarization induced by FSS was about 44mV. Voltage clamp indicated that this depolarization was enough to activated L-VSCCs in osteoblasts. These results suggested a time line of Ca(2+) mobilization wherein FSS activated SACs to promote Na(+) entry to depolarize membrane that, in turn, activated L-VSCCs and Ca(2+) influx though L-VSCCs switched on [Ca(2+)]i response in osteoblasts.

  8. Quenching of chlorophyll fluorescence induced by silver nanoparticles.

    PubMed

    Queiroz, A M; Mezacasa, A V; Graciano, D E; Falco, W F; M'Peko, J-C; Guimarães, F E G; Lawson, T; Colbeck, I; Oliveira, S L; Caires, A R L

    2016-11-05

    The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100nm of diameter). UV-Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles.

  9. Quenching of chlorophyll fluorescence induced by silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Queiroz, A. M.; Mezacasa, A. V.; Graciano, D. E.; Falco, W. F.; M'Peko, J.-C.; Guimarães, F. E. G.; Lawson, T.; Colbeck, I.; Oliveira, S. L.; Caires, A. R. L.

    2016-11-01

    The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100 nm of diameter). UV-Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678 nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles.

  10. Transient Cavitation Induced by High Amplitude Diagnostic Ultrasound.

    NASA Astrophysics Data System (ADS)

    Ayme, Eveline J.

    1988-07-01

    Study of the response of gaseous microbubbles to medical ultrasound is essential to apprehend the potentially dangerous effects of transient cavitation on living tissues. However, the prediction of such response is complicated by the finite -amplitude distortion associated with high amplitude acoustic fields. Through a combination of theoretical developments, computer simulations, and experiments, this dissertation investigates the consequences of the interaction between finite-amplitude distortion and transient cavitation, in the context of a diagnostic ultrasonic field. The theoretical approach is to synthesize the asymmetry between compression and rarefaction half-cycles which characterizes a typical nonlinearly distorted pulse obtained at the focus of a diagnostic transducer immersed in water. The synthetic pulse is used to drive a theoretical model for nonlinear bubble dynamics. Comparison with sinusoidal pulses "equivalent" to the distorted pulse as measured by a selection of descriptive parameters shows that: (i) the peak-positive pressure (P_{+} ) in the distorted pulse is a very poor predictor of transient cavitation, (ii) the peak-negative pressure (P_{-}) is a better indicator but underestimates the actual bubble response, (iii) the best predictor is the pressure amplitude of the fundamental (P_{F}) in a Fourier series representation of the distorted pulse. These predictions are tested experimentally on Drosophila larvae. The larvae are exposed to pulsed, symmetric, sinusoidal fields and to pulsed, asymmetric, distorted fields. The killing ratio of the larvae is plotted as a function of the same selection of descriptive parameters, namely P_{+}, P_{ -}, and P_{F}. The resulting curves are compared with the killing ratio plotted against the peak pressure in the sinusoidal, undistorted pulse (P_{A}). If the distorted pulse is described in terms of P_ {-} or P_{+} , the killing ratios are significantly different; if the distorted pulse is described in terms

  11. Transient cardio-respiratory responses to visually induced tilt illusions

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Ramsdell, C. D.; Mullen, T. J.; Oman, C. M.; Harm, D. L.; Paloski, W. H.

    2000-01-01

    Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

  12. Coupling of transient near infrared photonic with magnetic nanoparticle for potential dissipation-free biomedical application in brain

    PubMed Central

    Sagar, Vidya; Atluri, V. S. R.; Tomitaka, A.; Shah, P.; Nagasetti, A.; Pilakka-Kanthikeel, S.; El-Hage, N.; McGoron, A.; Takemura, Y.; Nair, M.

    2016-01-01

    Combined treatment strategies based on magnetic nanoparticles (MNPs) with near infrared ray (NIR) biophotonic possess tremendous potential for non-invasive therapeutic approach. Nonetheless, investigations in this direction have been limited to peripheral body region and little is known about the potential biomedical application of this approach for brain. Here we report that transient NIR exposure is dissipation-free and has no adverse effect on the viability and plasticity of major brain cells in the presence or absence superparamagnetic nanoparticles. The 808 nm NIR laser module with thermocouple was employed for functional studies upon NIR exposure to brain cells. Magnetic nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic laser scattering (DLS), and vibrating sample magnetometer (VSM). Brain cells viability and plasticity were analyzed using electric cell-substrate impedance sensing system, cytotoxicity evaluation, and confocal microscopy. When efficacious non-invasive photobiomodulation and neuro-therapeutical targeting and monitoring to brain remain a formidable task, the discovery of this dissipation-free, transient NIR photonic approach for brain cells possesses remarkable potential to add new dimension. PMID:27465276

  13. Coupling of transient near infrared photonic with magnetic nanoparticle for potential dissipation-free biomedical application in brain

    NASA Astrophysics Data System (ADS)

    Sagar, Vidya; Atluri, V. S. R.; Tomitaka, A.; Shah, P.; Nagasetti, A.; Pilakka-Kanthikeel, S.; El-Hage, N.; McGoron, A.; Takemura, Y.; Nair, M.

    2016-07-01

    Combined treatment strategies based on magnetic nanoparticles (MNPs) with near infrared ray (NIR) biophotonic possess tremendous potential for non-invasive therapeutic approach. Nonetheless, investigations in this direction have been limited to peripheral body region and little is known about the potential biomedical application of this approach for brain. Here we report that transient NIR exposure is dissipation-free and has no adverse effect on the viability and plasticity of major brain cells in the presence or absence superparamagnetic nanoparticles. The 808 nm NIR laser module with thermocouple was employed for functional studies upon NIR exposure to brain cells. Magnetic nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic laser scattering (DLS), and vibrating sample magnetometer (VSM). Brain cells viability and plasticity were analyzed using electric cell-substrate impedance sensing system, cytotoxicity evaluation, and confocal microscopy. When efficacious non-invasive photobiomodulation and neuro-therapeutical targeting and monitoring to brain remain a formidable task, the discovery of this dissipation-free, transient NIR photonic approach for brain cells possesses remarkable potential to add new dimension.

  14. Solvent-induced configuration mixing and triplet excited-state inversion: insights from transient absorption and transient dc photoconductivity measurements.

    PubMed

    She, Chunxing; Rachford, Aaron A; Wang, Xianghuai; Goeb, Sébastien; El-Ballouli, Ala'a O; Castellano, Felix N; Hupp, Joseph T

    2009-10-14

    Solvent-induced excited-state configuration mixing in a Pt(II) diimine chromophore with phenylene ethynylene containing acetylide ligands, [Pt((t)Bu2bpy)(PE3)2] (1), was characterized by nanosecond transient absorption spectroscopy and transient dc photoconductivity (TDCP). The mixing is a result of closely spaced triplet charge transfer (3CT) and intraligand-localized (3IL) triplet energy levels that are finely tuned with solvent polarity as ascertained by their parent model chromophores [Pt((t)Bu2bpy)(PE1)2] (2) and [Pt(P2)(PE3)2] (3), respectively. The absorption difference spectrum of the mixed triplet state is dramatically different from those of the 3CT and 3IL state model chromophores. The 3CT, 3IL and configuration-mixed triplet states led to distinct TDCP signals. The TDCP response is of negative polarity for 3CT excited states but of positive polarity for 3IL excited states. TDCP transients for 1 in mixed solvents are a combination of signals from the 3IL and 3CT states, with the signal magnitude depending on the polarity of solvent composition. The fraction of 3CT state character in the configurationally mixed excited state was quantified by TDCP to be approximately 0.24 in pure benzene, while it decreased to approximately 0.05 in 20 : 80 (v : v) benzene-CH2Cl2. The charge transfer fraction appears to increase slightly to approximately 0.11 in the lower polarity 20 : 80 n-hexane-CH2Cl2 medium. TDCP is shown to be a useful tool for the identification of the lowest excited state in electrically neutral metal-organic chromophores.

  15. Transient photoacoustic effects induced in liquids by pulsed erbium lasers

    NASA Astrophysics Data System (ADS)

    Frenz, Martin; Pratisto, Hans; Ith, Michael; Asshauer, Thomas; Rink, Klaus; Delacretaz, Guy P.; Romano, Valerio; Salathe, Rene-Paul; Weber, Heinz P.

    1994-08-01

    The intense interest in the investigation of erbium laser radiation in medicine is due to the fact that radiation at 3 micrometers is very strongly absorbed by water, which is present in all biological tissue. As a consequence of this high absorption the interaction of pulsed radiation is characterized by an explosive process with a low ablation threshold and a thin coagulation zone along the laser incisions. Erbium lasers, therefore, have a wide field of potential medical applications which become even more attractive with the availability of reliable delivery systems. An interesting situation arises in orthopaedics and angioplasty, where a precise cutting instrument is needed in a liquid environment. For this reason, we experimentally investigated the interaction mechanism of fiber transmitted, pulsed, free-running and Q- switched Erbium:YSGG ((lambda) equals 2.79 micrometers ) and Erbium:YAG ((lambda) equals 2.94 micrometers ) laser radiation with liquid water. The dynamics of the bubble formation and the propagation of shockwaves in water was studied and visualized by flash photography. Acoustic transients of a few hundreds of bars accompanying the ablation process were measured with a needle hydrophone. A clear correlation between the spikes of the laser pulse and those of the pressure signal was observed. Additionally, strong pressure transients were measured after the end of the laser pulse, which could be associated with the collapse of the vapor bubble and further collapses after multiple rebounds. The influence of pulse energy, fiber size and pulse duration on the formation and the amplitude of the pressure waves is demonstrated.

  16. New transient absorption observed in the spectrum of colloidal CdSe nanoparticles pumped with high-power femtosecond pulses

    SciTech Connect

    Burda, C.; Link, S.; Green, T.C.; El-Sayed, M.A.

    1999-12-09

    The power dependence of the transient absorption spectrum of CdSe nanoparticle colloids with size distribution of 4.0 {+-} 0.4 nm diameter is studied with femtosecond pump-probe techniques. At the lowest pump laser power, the absorption bleaching (negative spectrum) characteristic of the exciton spectrum is observed with maxima at 560 and 480 nm. As the pump laser power increases, two new transient absorptions at 510 and 590 nm with unresolved fast rise (<100 fs) and long decay times ({much{underscore}gt}150 ps) are observed. The energy of each of the positive absorption is red shifted from that of the bleach bands by {approximately}120 MeV. The origin of this shift is discussed in terms of the effect of the internal electric field of the many electron-hole pairs formed within the quantum dot at the high pump intensity, absorption from a metastable excited state or the formation of biexcitons.

  17. Alloying of metal nanoparticles by ion-beam induced sputtering

    NASA Astrophysics Data System (ADS)

    Magudapathy, P.; Srivastava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Saravanan, K.; Das, A.; Panigrahi, B. K.

    2017-01-01

    Ion-beam sputtering technique has been utilized for controlled synthesis of metal alloy nanoparticles of compositions that can be tuned. Analysis of various experimental results reveals the formation of Ag-Cu alloy nanoparticles on a silica substrate. Surface-plasmon optical resonance positions and observed shifts of Ag Bragg angles in X-ray diffraction pattern particularly confirm formation of alloy nanoparticles on glass samples. Sputtering induced nano-alloying mechanism has been discussed and compared with thermal mixing of Ag and Cu thin films on glass substrates. Compositions and sizes of alloy nanoparticles formed during ion-beam induced sputtering are found to exceed far from the values of thermal mixing.

  18. Aggregation in charged nanoparticles solutions induced by different interactions

    NASA Astrophysics Data System (ADS)

    Abbas, S.; Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

    2016-05-01

    Small-angle neutron scattering (SANS) has been used to study the aggregation of anionic silica nanoparticles as induced through different interactions. The nanoparticle aggregation is induced by addition of salt (NaCl), cationic protein (lysozyme) and non-ionic surfactant (C12E10) employing different kind of interactions. The results show that the interaction in presence of salt can be explained using DLVO theory whereas non-DLVO forces play important role for interaction of nanoparticles with protein and surfactant. The presence of salt screens the repulsion between charged nanoparticles giving rise to a net attraction in the DLVO potential. On the other hand, strong electrostatic attraction between nanoparticle and oppositely charged protein leads to protein-mediated nanoparticle aggregation. In case of non-ionic surfactant, the relatively long-range attractive depletion interaction is found to be responsible for the particle aggregation. Interestingly, the completely different interactions lead to similar kind of aggregate morphology. The nanoparticle aggregates formed are found to have mass fractal nature having a fractal dimension (~2.5) consistent with diffusion limited type of fractal morphology in all three cases.

  19. Ion transport through dimethyl sulfoxide (DMSO) induced transient water pores in cell membranes.

    PubMed

    He, Fei; Liu, Weirong; Zheng, Shengchao; Zhou, Li; Ye, Benlan; Qi, Zhi

    2012-01-01

    It is well known that dimethyl sulphoxide (DMSO) increases membrane permeability, which makes it widely used as a vehicle to facilitate drug delivery across biological membranes. However, the mechanism of how DMSO increases membrane permeability has not been well understood. Recently, molecular dynamics simulations have demonstrated that DMSO can induce water pores in biological membranes, but no direct experimental evidence is so far available to prove the simulation result. Using FluxOR Tl⁺ influx assay and intracellular Ca²⁺ imaging technique, we studied the effect of DMSO on Tl⁺ and Ca²⁺ permeation across cell membranes. Upon application of DMSO on CHO-K1 cell line, Tl⁺ influx was transiently increased in a dose-dependent manner. The increase in Tl⁺ permeability induced by DMSO was not changed in the presence of blockers for K⁺ channel and Na⁺-K⁺ ATPase, suggesting that Tl⁺ permeates through transient water pores induced by DMSO to enter into the cell. In addition, Ca²⁺ permeability was significantly increased upon application of DMSO, indicating that the transient water pores induced by DMSO were non-selective pores. Furthermore, similar results could be obtained from RAW264.7 macrophage cell line. Therefore, this study provided experimental evidence to support the prediction that DMSO can induce transient water pores in cell membranes, which in turn facilitates the transport of active substances across membranes.

  20. Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects

    PubMed Central

    Nunes, Allancer DC; Ramalho, Laylla S; Souza, Álvaro PS; Mendes, Elizabeth P; Colugnati, Diego B; Zufelato, Nícholas; Sousa, Marcelo H; Bakuzis, Andris F; Castro, Carlos H

    2014-01-01

    Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (−dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications. PMID:25031535

  1. Implantation induced extended defects and transient enhanced diffusion in silicon

    SciTech Connect

    Chen, J.; Liu, J.; Listebarger, J.; Krishnamoorthy, W.; Zhang, L.; Jones, K.S.

    1995-08-01

    Transient enhanced diffusion (TED) of dopant in silicon caused by point defects during annealing of implanted. Si has become one of the essential concerns in miniaturization of silicon device technology. In order to control and minimize the TED effect, a fundamental understanding of the evolution of the point defects upon annealing and the interaction between point defects and extended defects and their effects on dopant diffusion is necessary. Our studies were carried out by two parts; (1) For understanding the evolution of <311> and <110> defects, B{sup +} and Si{sup +} implantation at energies (from 5 keV to 40 keV) and doses in the range from 5 x 10{sup 12} to 1 x 10{sup 14}/cm{sup 2} were used. The annealing kinetics were investigated using a N{sub 2} ambient with temperatures for time ranging from 500{degrees}C to 1100{degrees}C for time ranging from 3 min to 3 hours. A matrix of implant energy vs. dose on formation threshold of <311> and <110> defect, interstitials napped and dissolved condition were obtained. (2) For Understanding the interaction between Type II dislocation loop and point defect a B doped buried marker layer was used. The oxidation of silicon surface used as a interstitials injection source and a buried type II loop layer as a point defect detector used to quantify the flux of interstitials injected. Combining the flux measured by loops and dopant diffusion the D{sub I} C{sub I} was determined. The diffusion limited kinetics was concluded. The TED from <311> and EOR (End of Range) <110> defect was studied using 8keV B{sup +} implanted Si to a dose of the le14 and 190keV Ge{sub +} implanted to a dose of le15. Subsequent anneals are done for 5 min and 30 min, respectively, These defects affect dopant diffusion by trapping and releasing point defects.

  2. Nanoparticle-induced unusual melting and solidification behaviours of metals.

    PubMed

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-18

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage.

  3. Nanoparticle-induced unusual melting and solidification behaviours of metals

    NASA Astrophysics Data System (ADS)

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage.

  4. The significance of nanoparticles in particle-induced pulmonary fibrosis

    PubMed Central

    Byrne, James D; Baugh, John A

    2008-01-01

    Exposure to airborne nanoparticles contributes to many chronic pulmonary diseases. Nanoparticles, classified as anthropogenic and natural particles, and fibers of diameters less than 100 nm, have unrestricted access to most areas of the lung due to their size. Size relates to the deposition efficiency of the particle, with particles in the nano-range having the highest efficiencies. The deposition of nanoparticles in the lung can lead to chronic inflammation, epithelial injury, and further to pulmonary fibrosis. Cases of particle-induced pulmonary fibrosis, namely pneumoconiosis, are mostly occupationally influenced, and continue to be documented around the world. The tremendous growth of nanotechnology, however, has spurred fears of increased rates of pulmonary diseases, especially fibrosis. The severity of toxicological consequences warrants further examination of the effects of nanoparticles in humans, possible treatments and increased regulatory measures. PMID:18523535

  5. A single transient episode of hyperammonemia induces long-lasting alterations in protein kinase A.

    PubMed

    Montoliu, Carmina; Piedrafita, Blanca; Serra, Miguel A; del Olmo, Juan A; Rodrigo, José M; Felipo, Vicente

    2007-01-01

    Hepatic encephalopathy in patients with liver disease is associated with poor prognosis. This could be due to the induction by the transient episode of hepatic encephalopathy of long-lasting alterations making patients more susceptible. We show that a single transient episode of hyperammonemia induces long-lasting alterations in signal transduction. The content of the regulatory subunit of the protein kinase dependent on cAMP (PKA-RI) is increased in erythrocytes from cirrhotic patients. This increase is reproduced in rats with portacaval anastomosis and in rats with hyperammonemia without liver failure, suggesting that hyperammonemia is responsible for increased PKA-RI in patients. We analyzed whether there is a correlation between ammonia levels and PKA-RI content in patients. All cirrhotic patients had increased content of PKA-RI. Some of them showed normal ammonia levels but had suffered previous hyperammonemia episodes. This suggested that a single transient episode of hyperammonemia could induce the long-lasting increase in PKA-RI. To assess this, we injected normal rats with ammonia and blood was taken at different times. Ammonia returned to basal levels at 2 h. However, PKA-RI was significantly increased in blood cells from rats injected with ammonia 3 wk after injection. In conclusion, it is shown that a single transient episode of hyperammonemia induces long-lasting alterations in signal transduction both in blood and brain. These alterations may contribute to the poor prognosis of patients suffering hepatic encephalopathy.

  6. Distinguishing cells by their first-order transient motion response under an optically induced dielectrophoretic force field

    NASA Astrophysics Data System (ADS)

    Zhao, Yuliang; Liang, Wenfeng; Zhang, Guanglie; Mai, John D.; Liu, Lianqing; Lee, Gwo-Bin; Li, Wen J.

    2013-10-01

    This letter reports our characterization of the transient motion of cells under an optically induced dielectrophoresis (ODEP) force field. Different types of human cells repeatably undergo a first-order transient motion response when subjected to a specific ODEP force field. A kernel function is derived to describe this transient motion. This function can be generally matched to experimental data for Raji cells and red blood cells by measuring two parameters: the initial velocity and the transient time-constant. They are uniquely different for Raji cells and RBCs. Support vector machine is used to distinguish between them based on their transient response characteristics.

  7. Transient Cardiomyopathy and Quadriplegia Induced by Ephedrine Decongestant.

    PubMed

    Snipelisky, David F; Kurklinsky, Andrew K; Chirila, Razvan

    2015-12-01

    Ephedrine decongestant products are widely used. Common side effects include palpitations, nervousness, and headache. More severe adverse reactions include cardiomyopathy and vasospasm. We report the case of an otherwise healthy 37-year-old woman who presented with acute-onset quadriplegia and heart failure. She had a normal chest radiograph on admission, but developed marked pulmonary edema and bilateral effusions the next day. Echocardiography revealed a left ventricular ejection fraction of 0.18 and no obvious intrinsic pathologic condition such as foramen narrowing on spinal imaging. Laboratory screening was positive for methamphetamines in the urine, and the patient admitted to having used, over the past several weeks, multiple ephedrine-containing products for allergy-symptom relief. She was ultimately diagnosed with an acute catecholamine-induced cardiomyopathy and spinal artery vasospasm consequential to excessive use of decongestants. Her symptoms resolved completely with supportive care and appropriate heart-failure management. An echocardiogram 2 weeks after admission showed improvement of the left ventricular ejection fraction to 0.33. Ten months after the event, the patient was entirely asymptomatic and showed further improvement of her ejection fraction to 0.45. To our knowledge, ours is the first report of spinal artery vasospasm resulting in quadriplegia in a human being after ephedrine ingestion.

  8. X-ray detection of transient magnetic moments induced by a spin current in Cu

    SciTech Connect

    Kukreja, R.; Bonetti, S.; Chen, Z.; Backes, D.; Acremann, Y.; Katine, J.; Kent, A. D.; Durr, H. A.; Ohldag, H.; Stohr, J.

    2015-08-24

    We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10–5μB on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott’s two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10–3μB per atom. As a result, this reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.

  9. Wasp venom blocks central cholinergic synapses to induce transient paralysis in cockroach prey.

    PubMed

    Haspel, G; Libersat, F

    2003-03-01

    The parasitoid wasp Ampulex compressa induces a set of unique behavioral effects upon stinging its prey, the cockroach. It stings into the first thoracic segment inducing 2 to 3 min of transient flaccid paralysis of the front legs. This facilitates a second sting in the cockroach's head that induces 30 min of excessive grooming followed by a 2 to 5-week long lethargic state. In the present study, we examine the immediate effect of the first sting, which is a transient paralysis of the front legs. Using radiolabeled wasps, we demonstrate that the wasp injects its venom directly into the cockroach's first thoracic ganglion. The artificial injection of milked venom into a thoracic ganglion abolishes spontaneous and evoked responses of the motoneurons associated with leg movements. To investigate the physiological mechanism of action of the venom, we injected venom into the last abdominal ganglion of the cockroach, which houses a well-characterized cholinergic synapse. Injected venom abolishes both sensory-evoked and agonist-evoked postsynaptic potentials recorded in the postsynaptic neuron for 2 to 3 min without affecting action potential propagation. Thus, the venom blocking effect has a postsynaptic component that follows the same time course as the transient paralysis induced by the thoracic sting. Finally, injection of a nicotinic antagonist in the front thoracic ganglion induces paralysis of the front legs. We conclude that the transient paralytic effect of the thoracic sting can be mainly accounted for by the presence of a venom active component that induces a postsynaptic block of central cholinergic synaptic transmission.

  10. Relative logic cell placement for mitigation of charge sharing-induced transients

    NASA Astrophysics Data System (ADS)

    Kiddie, Bradley T.; Robinson, William H.

    2016-10-01

    Design of modern integrated circuits increasingly requires consideration of radiation effects, especially in space and other high-risk environments. With fabrication technologies scaling down both feature sizes and critical charge, a radiation strike in sub-100 nm technologies may affect multiple, physically adjacent nodes. With increasing clock speeds, transient errors in the processing datapath also increase in risk. Modeling single-event multiple-transients (SEMT) for pre-fabrication reliability characterization has become a more common design step, and this work adds to the state-of-the-art by providing a fast and physically-informed characterization flow that captures the effects of single-event multiple-node charge collection through experimentally observed transport mechanisms. Beyond characterization, the study of SEMT vulnerabilities reveals the electronic design automation (EDA) step of standard logic cell placement as a design space for hardening against SEMT-induced errors. This work: (1) analyzes the vulnerability of benchmark circuits against SEMT errors, (2) evaluates the impact of logic on transient propagation, (3) explores EDA placement techniques, and (4) builds an automated design flow for relative placement of cells to mask transient errors, while maintaining compatibility with other radiation hardening techniques. Zero cost to area and marginal impact on timing enable this new cell placement algorithm that masks 30% of SEMT-induced errors.

  11. Resveratrol-loaded Nanoparticles Induce Antioxidant Activity against Oxidative Stress

    PubMed Central

    Kim, Jae-Hwan; Park, Eun-Young; Ha, Ho-Kyung; Jo, Chan-Mi; Lee, Won-Jae; Lee, Sung Sill; Kim, Jin Wook

    2016-01-01

    Resveratrol acts as a free radical scavenger and a potent antioxidant in the inhibition of numerous reactive oxygen species (ROS). The function of resveratrol and resveratrol-loaded nanoparticles in protecting human lung cancer cells (A549) against hydrogen peroxide was investigated in this study. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay was performed to evaluate the antioxidant properties. Resveratrol had substantially high antioxidant capacity (trolox equivalent antioxidant capacity value) compared to trolox and vitamin E since the concentration of resveratrol was more than 50 μM. Nanoparticles prepared from β-lactoglobulin (β-lg) were successfully developed. The β-lg nanoparticle showed 60 to 146 nm diameter in size with negatively charged surface. Non-cytotoxicity was observed in Caco-2 cells treated with β-lg nanoparticles. Fluorescein isothiocynate-conjugated β-lg nanoparticles were identified into the cell membrane of Caco-2 cells, indicating that nanoparticles can be used as a delivery system. Hydrogen peroxide caused accumulation of ROS in a dose- and time-dependent manner. Resveratrol-loaded nanoparticles restored H2O2-induced ROS levels by induction of cellular uptake of resveratrol in A549 cells. Furthermore, resveratrol activated nuclear factor erythroid 2-related factor 2-Kelch ECH associating protein 1 (Nrf2-Keap1) signaling in A549 cells, thereby accumulation of Nrf2 abundance, as demonstrated by western blotting approach. Overall, these results may have implications for improvement of oxidative stress in treatment with nanoparticles as a biodegradable and non-toxic delivery carrier of bioactive compounds. PMID:26732454

  12. Assessment of fission-gas-induced transient swelling in metallic fuel

    SciTech Connect

    Sevy, R H; Cahalan, J E

    1985-03-01

    A model for fission-gas-induced transient swelling in metallic fuel is described. An observation that the strength of metallic fuel becomes very small at a temperature several hundred degrees below the solidus forms the basis for an assumption that, above this temperature, the fuel proceeds through a series of stress-free equilibrium states for a large range of heating rates. Gas bubble coalescence and growth and any effects from ingested sodium are ignored such that the model may tend to underestimate swelling in some circumstances. The fuel swelling model is used to predict the reactivity effect of fission-gas-induced axial expansion of metallic fuel during transient overpower excursions. Comparisons to oxide fuel behavior are made. Sensitivity of results to metallic fuel modeling assumptions are assessed in a parametric study.

  13. Laser-induced incandescence from laser-heated silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Menser, Jan; Daun, Kyle; Dreier, Thomas; Schulz, Christof

    2016-11-01

    This work describes the application of temporally and spectrally resolved laser-induced incandescence to silicon nanoparticles synthesized in a microwave plasma reactor. Optical properties for bulk silicon presented in the literature were extended for nanostructured particles analyzed in this paper. Uncertainties of parameters in the evaporation submodel, as well as measurement noise, are incorporated into the inference process by Bayesian statistics. The inferred nanoparticle sizes agree with results from transmission electron microscopy, and the determined accommodation coefficient matches the values of the preceding study.

  14. Heavy Ion Microbeam- and Broadbeam-Induced Transients in SiGe HBTs

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Reed, Robert A.; McMorrow, Dale; Vizkelethy, Gyorgy; Ferlet-Cavrois, Veronique; Baggio, Jacques; Duhamel, Olivier; Moen, Kurt A.; Phillips, Stanley D.; Diestelhorst, Ryan M.; Cressler, John D.; Sutton, Akil K.; Raman, Ashok; Turowski, Marek; Dodd, Paul E.; Alles, Michael L.; Schrimpf, Ronald D.; Marshall, Paul W.; LaBel, Kenneth A.

    2009-01-01

    SiGe HBT heavy ion-induced current transients are measured using Sandia National Laboratories microbeam and high- and low-energy broadbeam sources at the Grand Accelerateur National d'Ions Lourds and the University of Jyvaskyla. The data were captured using a custom broadband IC package and real-time digital phosphor oscilloscopes with at least 16 GHz of analog bandwidth. These data provide detailed insight into the effects of ion strike location, range, and LET.

  15. Transient competition between photocatalysis and carrier recombination in TiO2 nanotube film loaded with Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Shao, Zhu-Feng; Yang, Yan-Qiang; Liu, Shu-Tian; Wang, Qiang

    2014-09-01

    Highly ordered TiO2 nanotube array (TNA) films are fabricated by using an anodic oxidation method. Au nanoparticles (NPs) films are decorated onto the top of TNA films with the aid of ion-sputtering and thermal annealing. An enhanced photocatalytic activity under ultraviolet C (UVC, 266 nm) light irradiation is obtained compared with that of the pristine TNA, which is shown by the steady-state photoluminescence (PL) spectra. Furthermore, a distinct blue shift in the nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra is observed. Such a phenomenon could be well explained by considering the competition between the surface photocatalytic process and the recombination of the photo-generated carriers. The enhanced UV photocatalytic activities of the Au—TNA composite are evaluated through photo-degradation of methyl orange (MO) in an aqueous solution with ultraviolet—visible absorption spectrometry. Our current work may provide a simple strategy to synthesize defect-related composite photocatalytic devices.

  16. [Role of Transient Receptor Potential Channels in Paclitaxel- and Oxaliplatin-induced Peripheral Neuropathy].

    PubMed

    Taguchi, Kyoji

    2016-01-01

    Peripheral neuropathy is a common adverse effect of paclitaxel and oxaliplatin treatment. The major dose-limiting side effect of these drugs is peripheral sensory neuropathy. The symptoms of paclitaxel-induced neuropathy are mostly sensory and peripheral in nature, consisting of mechanical allodynia/hyperalgesia, tingling, and numbness. Oxaliplatin-induced neurotoxicity manifests as rapid-onset neuropathic symptoms that are exacerbated by cold exposure and as chronic neuropathy that develops after several treatment cycles. Although many basic and clinical researchers have studied anticancer drug-induced peripheral neuropathy, the mechanism is not well understood. In this review, we focus on (1) analysis of transient receptor potential vanilloid 1 (TRPV1) channel expression in the rat dorsal root ganglion (DRG) after paclitaxel treatment and (2) analysis of transient receptor potential ankyrin 1 (TRPA1) channel in the DRG after oxaliplatin treatment. This review describes that (1) paclitaxel-induced neuropathic pain may be the result of up-regulation of TRPV1 in small- and medium-diameter DRG neurons. In addition, paclitaxel treatment increases the release of substance P, but not calcitonin gene-related peptide, in the superficial layers of the spinal dorsal horn. (2) TRPA1 expression via activation of p38 mitogen-activated protein kinase in small-diameter DRG neurons, at least in part, contributes to the development of oxaliplatin-induced acute cold hyperalgesia. We suggest that TRPV1 or TRPA1 antagonists may be potential therapeutic lead compounds for treating anticancer drug-induced peripheral neuropathy.

  17. Laser-induced plasma generation and evolution in a transient spray.

    PubMed

    Kawahara, Nobuyuki; Tsuboi, Kazuya; Tomita, Eiji

    2014-01-13

    The behaviors of laser-induced plasma and fuel spray were investigated by visualizing images with an ultra-high-speed camera. Time-series images of laser-induced plasma in a transient spray were visualized using a high-speed color camera. The effects of a shockwave generated from the laser-induced plasma on the evaporated spray behavior were investigated. The interaction between a single droplet and the laser-induced plasma was investigated using a single droplet levitated by an ultrasonic levitator. Two main conclusions were drawn from these experiments: (1) the fuel droplets in the spray were dispersed by the shockwave generated from the laser-induced plasma; and (2) the plasma position may have shifted due to breakdown of the droplet surface and the lens effect of droplets.

  18. Significance of Persistent Inflammation in Respiratory Disorders Induced by Nanoparticles

    PubMed Central

    Morimoto, Yasuo; Izumi, Hiroto; Kuroda, Etsushi

    2014-01-01

    Pulmonary inflammation, especially persistent inflammation, has been found to play a key role in respiratory disorders induced by nanoparticles in animal models. In inhalation studies and instillation studies of nanomaterials, persistent inflammation is composed of neutrophils and alveolar macrophages, and its pathogenesis is related to chemokines such as the cytokine-induced neutrophil chemoattractant (CINC) family and macrophage inflammatory protein-1α and oxidant stress-related genes such as heme oxygenase-1 (HO-1). DNA damages occur chemically or physically by nanomaterials. Chemical and physical damage are associated with point mutation by free radicals and double strand brake, respectively. The failure of DNA repair and accumulation of mutations might occur when inflammation is prolonged, and finally normal cells could become malignant. These free radicals can not only damage cells but also induce signaling molecules containing immunoreaction. Nanoparticles and asbestos also induce the production of free radicals. In allergic responses, nanoparticles act as Th2 adjuvants to activate Th2 immune responses such as activation of eosinophil and induction of IgE. Taken together, the presence of persistent inflammation may contribute to the pathogenesis of a variety of diseases induced by nanomaterials. PMID:25097864

  19. Glibenclamide decreases ATP-induced intracellular calcium transient elevation via inhibiting reactive oxygen species and mitochondrial activity in macrophages.

    PubMed

    Li, Duo-ling; Ma, Zhi-yong; Fu, Zhi-jie; Ling, Ming-ying; Yan, Chuan-zhu; Zhang, Yun

    2014-01-01

    Increasing evidence has revealed that glibenclamide has a wide range of anti-inflammatory effects. However, it is unclear whether glibenclamide can affect the resting and adenosine triphosphate (ATP)-induced intracellular calcium ([Ca(2+)]i) handling in Raw 264.7 macrophages. In the present study, [Ca(2+)]i transient, reactive oxygen species (ROS) and mitochondrial activity were measured by the high-speed TILLvisION digital imaging system using the indicators of Fura 2-am, DCFDA and rhodamine-123, respectively. We found that glibenclamide, pinacidil and other unselective K(+) channel blockers had no effect on the resting [Ca(2+)]i of Raw 264.7 cells. Extracellular ATP (100 µM) induced [Ca(2+)]i transient elevation independent of extracellular Ca(2+). The transient elevation was inhibited by an ROS scavenger (tiron) and mitochondria inhibitor (rotenone). Glibenclamide and 5-hydroxydecanoate (5-HD) also decreased ATP-induced [Ca(2+)]i transient elevation, but pinacidil and other unselective K(+) channel blockers had no effect. Glibenclamide also decreased the peak of [Ca(2+)]i transient induced by extracellular thapsigargin (Tg, 1 µM). Furthermore, glibenclamide decreased intracellular ROS and mitochondrial activity. When pretreated with tiron and rotenone, glibenclamide could not decrease ATP, and Tg induced maximal [Ca(2+)]i transient further. We conclude that glibenclamide may inhibit ATP-induced [Ca(2+)]i transient elevation by blocking mitochondria KATP channels, resulting in decreased ROS generation and mitochondrial activity in Raw 264.7 macrophages.

  20. Superior neuroprotective effects of cerebrolysin in nanoparticle-induced exacerbation of hyperthermia-induced brain pathology.

    PubMed

    Sharma, Aruna; Muresanu, Dafin Fior; Mössler, Herbert; Sharma, Hari Shanker

    2012-02-01

    In recent years, the incidence of heat stroke and associated brain pathology are increasing Worldwide. More than half of the world's population are living in areas associated with high environmental heat especially during the summer seasons. Thus, new research is needed using novel drug targets to achieve neuroprotection in heat-induced brain pathology. Previous research from our laboratory showed that the pathophysiology of brain injuries following heat stroke are exacerbated by chronic intoxication of engineered nanoparticles of small sizes (50-60 nm) following identical heat exposure in rats. Interestingly, in nanoparticle-intoxicated animals the known neuroprotective agents in standard doses failed to induce effective neuroprotection. This suggests that the dose-response of the drugs either requires modification or new therapeutic agents are needed to provide better neuroprotection in nanoparticle-intoxicated animals after heat stroke. This review is focused on the use of cerebrolysin, a mixture of several neurotrophic factors and active peptide fragments, in relation to other neuroprotective agents normally used to treat ischemic stroke in clinics in nanoparticle-induced exacerbation of brain damage in heat stroke. It appears that cerebrolysin exerts the most superior neuroprotective effects in heat stress as compared to other neuroprotective agents on brain pathology in normal rats. Interestingly, to induce effective neuroprotection in nanoparticle-induced exacerbation of brain pathology a double dose of cerebrolysin is needed. On the other hand, double doses of the other drugs were quite ineffective in reducing brain damage. These observations suggest that the drug type and doses are important factors in attenuating nanoparticle-induced exacerbation of brain pathology in heat stroke. The functional significance and possible mechanisms of drug-induced neuroprotection in nanoparticle-treated, heat-stressed rats are discussed.

  1. Induced phase transitions of nanoparticle-stabilized emulsions

    NASA Astrophysics Data System (ADS)

    Frijters, Stefan; Günther, Florian; Harting, Jens

    2013-11-01

    Nanoparticles can stabilize fluid-fluid interfaces over long timescales and are nowadays commonly used, e.g. in emulsions. However, their fundamental properties are as of yet poorly understood. Nanoparticle-stabilized emulsions can exhibit different phases, such as Pickering emulsions or bijels, which can be characterized by their different topologies and rheology. We investigate the effect of various initial conditions on random mixtures of two fluids and nanoparticles - in particular, the final state these systems will reach. For this, we use the well-established 3D lattice Boltzmann method, extended to allow for the added nanoparticles. After the evolution of the emulsions has stopped, we induce transitions from one state to another by gradually changing the wettability of the nanoparticles over time. This changes the preferential local curvature of the interfaces, which strongly affects the global state. We observe strong hysteresis effects because of the energy barrier presented by the necessary massive reordering of the particles. Being able to change emulsion states in situ has potential application possibilities in filtering technology, or creating particle scaffolds.

  2. Molecular dynamics simulations of evaporation-induced nanoparticle assembly

    NASA Astrophysics Data System (ADS)

    Cheng, Shengfeng; Grest, Gary S.

    2013-02-01

    While evaporating solvent is a widely used technique to assemble nano-sized objects into desired superstructures, there has been limited work on how the assembled structures are affected by the physical aspects of the process. We present large scale molecular dynamics simulations of the evaporation-induced assembly of nanoparticles suspended in a liquid that evaporates in a controlled fashion. The quality of the nanoparticle crystal formed just below the liquid/vapor interface is found to be better at relatively slower evaporation rates, as less defects and grain boundaries appear. This trend is understood as the result of the competition between the accumulation and diffusion times of nanoparticles at the liquid/vapor interface. When the former is smaller, nanoparticles are deposited so fast at the interface that they do not have sufficient time to arrange through diffusion, which leads to the prevalence of defects and grain boundaries. Our results have important implications in understanding assembly of nanoparticles and colloids in non-equilibrium liquid environments.

  3. Nanoparticles alloying in liquids: Laser-ablation-generated Ag or Pd nanoparticles and laser irradiation-induced AgPd nanoparticle alloying.

    PubMed

    Semaltianos, N G; Chassagnon, R; Moutarlier, V; Blondeau-Patissier, V; Assoul, M; Monteil, G

    2017-04-18

    Laser irradiation of a mixture of single-element micro/nanomaterials may lead to their alloying and fabrication of multi-element structures. In addition to the laser induced alloying of particulates in the form of micro/nanopowders in ambient atmosphere (which forms the basis of the field of additive manufacturing technology), another interesting problem is the laser-induced alloying of a mixture of single-element nanoparticles in liquids since this process may lead to the direct fabrication of alloyed-nanoparticle colloidal solutions. In this work, bare-surface ligand-free Ag and Pd nanoparticles in solution were prepared by laser ablation of the corresponding bulk target materials, separately in water. The two solutions were mixed and the mixed solution was laser irradiated for different time durations in order to investigate the laser-induced nanoparticles alloying in liquid. Nanoparticles alloying and the formation of AgPd alloyed nanoparticles takes place with a decrease of the intensity of the surface-plasmon resonance peak of the Ag nanoparticles (at ∼405 nm) with the irradiation time while the low wavelength interband absorption peaks of either Ag or Pd nanoparticles remain unaffected by the irradiation for a time duration even as long as 30 min. The nanoalloys have lattice constants with values between those of the pure metals, which indicates that they consist of Ag and Pd in an approximately 1:1 ratio similar to the atomic composition of the starting mixed-nanoparticle solution. Formation of nanoparticle networks consisting of bimetallic alloyed nanoparticles and nanoparticles that remain as single elements (even after the end of the irradiation), joining together, are also formed. The binding energies of the 3d core electrons of both Ag and Pd nanoparticles shift to lower energies with the irradiation time, which is also a typical characteristic of AgPd alloyed nanoparticles. The mechanisms of nanoparticles alloying and network formation are also

  4. Nanoparticles alloying in liquids: Laser-ablation-generated Ag or Pd nanoparticles and laser irradiation-induced AgPd nanoparticle alloying

    NASA Astrophysics Data System (ADS)

    Semaltianos, N. G.; Chassagnon, R.; Moutarlier, V.; Blondeau-Patissier, V.; Assoul, M.; Monteil, G.

    2017-04-01

    Laser irradiation of a mixture of single-element micro/nanomaterials may lead to their alloying and fabrication of multi-element structures. In addition to the laser induced alloying of particulates in the form of micro/nanopowders in ambient atmosphere (which forms the basis of the field of additive manufacturing technology), another interesting problem is the laser-induced alloying of a mixture of single-element nanoparticles in liquids since this process may lead to the direct fabrication of alloyed-nanoparticle colloidal solutions. In this work, bare-surface ligand-free Ag and Pd nanoparticles in solution were prepared by laser ablation of the corresponding bulk target materials, separately in water. The two solutions were mixed and the mixed solution was laser irradiated for different time durations in order to investigate the laser-induced nanoparticles alloying in liquid. Nanoparticles alloying and the formation of AgPd alloyed nanoparticles takes place with a decrease of the intensity of the surface-plasmon resonance peak of the Ag nanoparticles (at ∼405 nm) with the irradiation time while the low wavelength interband absorption peaks of either Ag or Pd nanoparticles remain unaffected by the irradiation for a time duration even as long as 30 min. The nanoalloys have lattice constants with values between those of the pure metals, which indicates that they consist of Ag and Pd in an approximately 1:1 ratio similar to the atomic composition of the starting mixed-nanoparticle solution. Formation of nanoparticle networks consisting of bimetallic alloyed nanoparticles and nanoparticles that remain as single elements (even after the end of the irradiation), joining together, are also formed. The binding energies of the 3d core electrons of both Ag and Pd nanoparticles shift to lower energies with the irradiation time, which is also a typical characteristic of AgPd alloyed nanoparticles. The mechanisms of nanoparticles alloying and network formation are also

  5. Surface spin polarization induced ferromagnetic Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Shih, Po-Hsun; Li, Wen-Hsien; Wu, Sheng Yun

    2016-05-01

    We report on the observation of ferromagnetic spin polarized moments in 4.5 nm Ag nanoparticles. Both ferromagnetic and diamagnetic responses to an applied magnetic field were detected. The spin polarized moments shown under non-linear thermoinduced magnetization appeared on the surface atoms, rather than on all the atoms in particles. The saturation magnetization departed substantially from the Bloch T3/2-law, showing the existence of magnetic anisotropy. The Heisenberg ferromagnetic spin wave model for Ha-aligned moments was then employed to identify the magnetic anisotropic energy gap of ~0.12 meV. Our results may be understood by assuming the surface magnetism model, in which the surface atoms give rise to polarized moments while the core atoms produce diamagnetic responses.

  6. A laser induced fluorescence technique for quantifying transient liquid fuel films utilising total internal reflection

    NASA Astrophysics Data System (ADS)

    Alonso, Mario; Kay, Peter J.; Bowen, Phil J.; Gilchrist, Robert; Sapsford, Steve

    2010-01-01

    This paper describes the development of a laser induced fluorescence (LIF) technique to quantify the thickness and spatial distribution of transient liquid fuel films formed as a result of spray-wall interaction. The LIF technique relies on the principle that upon excitation by laser radiation the intensity of the fluorescent signal from a tracer like 3-pentanone is proportional to the film thickness. A binary solution of 10% (v/v) of 3-pentanone in iso-octane is used as a test fuel with a Nd:YAG laser as the excitation light source (utilising the fourth harmonic at wavelength 266 nm) and an intensified CCD camera is used to record the results as fluorescent images. The propagation of the excitation laser beam through the optical piston is carefully controlled by total internal reflection so that only the fuel film is excited and not the airborne droplets above the film, which had been previously shown to induce significant error. Other known sources of error are also carefully minimised. Calibrated temporally resolved benchmark results of a transient spray from a gasoline direct injector impinging on a flat quartz crown under atmospheric conditions are presented, with observations and discussion of the transient development of the fuel film. The calibrated measurements are consistent with previous studies of this event and demonstrate the applicability of the technique particularly for appraisal of CFD predictions. The potential utilisation of the technique under typical elevated ambient conditions is commented upon.

  7. Simulation of intracellular [Formula: see text] transients in osteoblasts induced by fluid shear stress and its application.

    PubMed

    Sun, Junqing; Xie, Wenjun; Shi, Liang; Yu, Liyin; Zhang, Jianbao

    2017-04-01

    Intracellular [Formula: see text] transient induced by fluid shear stress (FSS) plays an important role in mechanical regulation of osteoblasts, but the cellular mechanism remains incompletely understood. Here, we constructed a mathematical model combined with experiments to elucidate it. Our simulated and experimental results showed that it was the delay of membrane potential repolarization to produce the refractory period of FSS-induced intracellular calcium transients in osteoblasts. Moreover, the results also demonstrated that the amplitude of FSS-induced intracellular calcium transient is crucial to the proliferation, while its duration is critical to the differentiation, of osteoblasts. Overall, the present study provides a way to understand the cellular mechanism of intracellular calcium transients in osteoblast induced by FSS and explains some of related physiological events.

  8. Cuprous oxide nanoparticles selectively induce apoptosis of tumor cells

    PubMed Central

    Wang, Ye; Zi, Xiao-Yuan; Su, Juan; Zhang, Hong-Xia; Zhang, Xin-Rong; Zhu, Hai-Ying; Li, Jian-Xiu; Yin, Meng; Yang, Feng; Hu, Yi-Ping

    2012-01-01

    In the rapid development of nanoscience and nanotechnology, many researchers have discovered that metal oxide nanoparticles have very useful pharmacological effects. Cuprous oxide nanoparticles (CONPs) can selectively induce apoptosis and suppress the proliferation of tumor cells, showing great potential as a clinical cancer therapy. Treatment with CONPs caused a G1/G0 cell cycle arrest in tumor cells. Furthermore, CONPs enclosed in vesicles entered, or were taken up by mitochondria, which damaged their membranes, thereby inducing apoptosis. CONPs can also produce reactive oxygen species (ROS) and initiate lipid peroxidation of the liposomal membrane, thereby regulating many signaling pathways and influencing the vital movements of cells. Our results demonstrate that CONPs have selective cytotoxicity towards tumor cells, and indicate that CONPs might be a potential nanomedicine for cancer therapy. PMID:22679374

  9. Light induced cytosolic drug delivery from liposomes with gold nanoparticles.

    PubMed

    Lajunen, Tatu; Viitala, Lauri; Kontturi, Leena-Stiina; Laaksonen, Timo; Liang, Huamin; Vuorimaa-Laukkanen, Elina; Viitala, Tapani; Le Guével, Xavier; Yliperttula, Marjo; Murtomäki, Lasse; Urtti, Arto

    2015-04-10

    Externally triggered drug release at defined targets allows site- and time-controlled drug treatment regimens. We have developed liposomal drug carriers with encapsulated gold nanoparticles for triggered drug release. Light energy is converted to heat in the gold nanoparticles and released to the lipid bilayers. Localized temperature increase renders liposomal bilayers to be leaky and triggers drug release. The aim of this study was to develop a drug releasing system capable of releasing its cargo to cell cytosol upon triggering with visible and near infrared light signals. The liposomes were formulated using either heat-sensitive or heat- and pH-sensitive lipid compositions with star or rod shaped gold nanoparticles. Encapsulated fluorescent probe, calcein, was released from the liposomes after exposure to the light. In addition, the pH-sensitive formulations showed a faster drug release in acidic conditions than in neutral conditions. The liposomes were internalized into human retinal pigment epithelial cells (ARPE-19) and human umbilical vein endothelial cells (HUVECs) and did not show any cellular toxicity. The light induced cytosolic delivery of calcein from the gold nanoparticle containing liposomes was shown, whereas no cytosolic release was seen without light induction or without gold nanoparticles in the liposomes. The light activated liposome formulations showed a controlled content release to the cellular cytosol at a specific location and time. Triggering with visual and near infrared light allows good tissue penetration and safety, and the pH-sensitive liposomes may enable selective drug release in the intracellular acidic compartments (endosomes, lysosomes). Thus, light activated liposomes with gold nanoparticles are an attractive option for time- and site-specific drug delivery into the target cells.

  10. Cerium oxide nanoparticle treatment ameliorates peritonitis-induced diaphragm dysfunction.

    PubMed

    Asano, Shinichi; Arvapalli, Ravikumar; Manne, Nandini D P K; Maheshwari, Mani; Ma, Bing; Rice, Kevin M; Selvaraj, Vellaisamy; Blough, Eric R

    2015-01-01

    The severe inflammation observed during sepsis is thought to cause diaphragm dysfunction, which is associated with poor patient prognosis. Cerium oxide (CeO2) nanoparticles have been posited to exhibit anti-inflammatory and antioxidative activities suggesting that these particles may be of potential use for the treatment of inflammatory disorders. To investigate this possibility, Sprague Dawley rats were randomly assigned to the following groups: sham control, CeO2 nanoparticle treatment only (0.5 mg/kg iv), sepsis, and sepsis+CeO2 nanoparticles. Sepsis was induced by the introduction of cecal material (600 mg/kg) directly into the peritoneal cavity. Nanoparticle treatment decreased sepsis-associated impairments in diaphragmatic contractile (P(o)) function (sham: 25.6±1.6 N/cm(2) vs CeO2: 23.4±0.8 N/cm(2) vs Sep: 15.9±1.0 N/cm(2) vs Sep+CeO2: 20.0±1.0 N/cm(2), P<0.05). These improvements in diaphragm contractile function were accompanied by a normalization of protein translation signaling (Akt, FOXO-1, and 4EBP1), diminished proteolysis (caspase 8 and ubiquitin levels), and decreased inflammatory signaling (Stat3 and iNOS). Histological analysis suggested that nanoparticle treatment was associated with diminished sarcolemma damage and diminished inflammatory cell infiltration. These data indicate CeO2 nanoparticles may improve diaphragmatic function in the septic laboratory rat.

  11. Transient photoconductivity in CdSe nanoparticles and nanocrystalline TiO2 as measured by time-resolved terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Schmuttenmaer, Charles A.; Turner, Gordon M.; Beard, Matthew C.

    2003-12-01

    The transient photoconductivity of dye-sensitized nanocrystalline colloidal TiO2 has been measured time-resolved THz spectroscopy (TRTS), a non-contact electrical probe with sub-picosecond temporal resolution. The photoconductivity deviates strongly from Drude behavior and is explained by disorder-induced carrier localization and/or backscattering of the photogenerated carriers. In addition, the carriers are found to thermally equilibrate with the lattice in roughly 300 femtoseconds. The size-dependent photoconductivity of CdSe nanoparticles ranging from 2.54 nm up to >25 nm has also been measured using TRTS. The measured change in the frequency-dependent optical density and change in phase of the transmitted THz pulse fall into three distinct groupings as a function of size and can be classified for diameters smaller than the Bohr exciton radius, diameters greater than the Bohr exciton radius but smaller than the bulk mean free path, and diameters greater than the bulk mean free path. The underlying cause of the grouping is a size-dependent mobility (or carrier scattering rate).

  12. Current-pulse-induced enhancement of transient photodetective effect in tilted manganite film.

    PubMed

    Ni, H; Zhao, K; Xi, J F; Feng, X; Xiang, W F; Zhao, S Q; Kong, Y-C; Wong, H K

    2012-12-17

    A current-pulse-induced enhancement effect of transient photovoltage has been discovered in tilted manganite La(2/3)Ca(1/3)MnO(3) film at room temperature. Here, by applying a pulsed current stimulus before pulse laser irradiation, we observed a significant enhancement of more than 50% in photovoltaic sensitivity. The current-pulse-induced photovoltaic enhancement can be tuned not only by the stimulating current value but also by the stimulating time. Such enhancement is time-sensitive and reproducible. This electrically induced effect, observed at room temperature, has both the benefit of a discovery in materials properties and the promise of applications for thin film manganites in photodetectors.

  13. Nanoparticle-induced unusual melting and solidification behaviours of metals

    PubMed Central

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage. PMID:28098147

  14. Chronic nicotine exposure exacerbates transient focal cerebral ischemia-induced brain injury.

    PubMed

    Li, Chun; Sun, Hong; Arrick, Denise M; Mayhan, William G

    2016-02-01

    Tobacco smoking is a risk factor contributing to the development and progression of ischemic stroke. Among many chemicals in tobacco, nicotine may be a key contributor. We hypothesized that nicotine alters the balance between oxidant and antioxidant networks leading to an increase in brain injury following transient focal cerebral ischemia. Male Sprague-Dawley were treated with nicotine (2 or 4 mg·kg(-1)·day(-1)) for 4 wk via an implanted subcutaneous osmotic minipump and subjected to a 2-h middle cerebral artery occlusion (MCAO). Infarct size and neurological deficits were evaluated at 24 h of reperfusion. Superoxide levels were determined by lucigenin-enhanced chemiluminescence. Expression of oxidant and antioxidant proteins was measured using Western blot analysis. We found that chronic nicotine exposure significantly increased infarct size and worsened neurological deficits. In addition, nicotine significantly elevated superoxide levels of cerebral cortex under basal conditions. Transient focal cerebral ischemia produced an increase in superoxide levels of cerebral cortex in control group, but no further increase was found in the nicotine group. Furthermore, chronic nicotine exposure did not alter protein expression of NADPH oxidase but significantly decreased MnSOD and uncoupling protein-2 (UCP-2) in the cerebral cortex and cerebral arteries. Our findings suggest that nicotine-induced exacerbation in brain damage following transient focal cerebral ischemia may be related to a preexisting oxidative stress via decreasing of MnSOD and UCP-2.

  15. 1D Cole-Cole inversion of TEM transients influenced by induced polarization

    NASA Astrophysics Data System (ADS)

    Seidel, Marc; Tezkan, Bülent

    2017-03-01

    Effects of induced polarization (IP) can have an impact on time-domain electromagnetic measurements (TEM) and may lead to sign reversals in the recorded transients. To study these IP effects on TEM data, a new 1D inversion algorithm was developed for both, the central-loop and the separate-loop TEM configurations using the Cole-Cole relaxation model. 1D forward calculations for a homogeneous half-space were conducted with the aim of analyzing the impacts of the Cole-Cole parameters on TEM transients with respect to possible sign reversals. The forward modelings showed that the variation of different parameters have comparable effects on the TEM transients. This leads to an increasing number of equivalent models as a result of inversion calculations. Subsequently, 1D inversions of synthetic data were performed to study the potentials and limitations of the algorithm regarding the resolution of the Cole-Cole parameters. In order to achieve optimal inversion results, it was essential to error-weight the data points in the direct vicinity of sign reversals. The obtained findings were eventually adopted on the inversion of real field data which contained considerable IP signatures such as sign reversals. One field data set was recorded at the Nakyn kimberlite field in Western Yakutiya, Russia, in the central-loop configuration. Another field data set originates from a waste site in Cologne, Germany, and was measured utilizing the separate-loop configuration.

  16. The performance of cable braids and terminations to lightning induced transients

    NASA Technical Reports Server (NTRS)

    Crofts, David

    1991-01-01

    The latest specification detailing the test waveforms for indirect lightning transients as applied to aircraft wiring systems specify very high voltages and currents. Although considerable data exists for measuring cable screen leakage using such methods as surface transfer impedance and bulk cable injection, there is little data on the likely core transient level that is likely to be induced from these threats. In particular, the new Waveform 5 at very high current levels (10 kA) is reputed to cause severe cable damage. A range of representative cables were made with various screen termination techniques and screening levels. These were tested first to determine their relative screening performance and then they were subjected to lightning transient testing to all the specified waveforms. Core voltages were measured for each test. Tests were also performed on bundles with fewer wires to determine the failure criteria with Waveform 5 and these tests also include flat conductor cables. The test showed that correctly terminated cable bundles performed well in all the tests and would provide a high level of protection to the electronic systems. The use of overbraides, provided the individual screens are well terminated, appears to be unnecessary.

  17. Nearwork-induced transient myopia (NITM) and permanent myopia--is there a link?

    PubMed

    Ciuffreda, Kenneth J; Vasudevan, Balamurali

    2008-03-01

    Myopia is a worldwide public health problem. However, its understanding is incomplete, and many of its preventative and therapeutic aspects remain controversial. Nearwork is a primary, environmentally based factor in the aetiology of permanent myopia (PM), with nearwork-induced transient myopia (NITM) being a possible contributory component. A relationship between PM and NITM has been suggested, but that connection has remained somewhat indirect and elusive. However, based on recent converging evidence from clinical, laboratory and modelling studies, a five-fold argument will be advanced for a possible link between PM and NITM.

  18. Magnetic field influence on the transient photoresistivity of defect-induced magnetic ZnO films

    NASA Astrophysics Data System (ADS)

    Zapata, C.; Khalid, M.; Simonelli, G.; Villafuerte, M.; Heluani, S. P.; Esquinazi, P.

    2011-09-01

    Magnetic field dependent photoresistivity was measured at 280 K in ZnO ferromagnetic films grown on r-plane Al2O3 under a N2 atmosphere. A correlation between the negative magneto photoresistivity and the existence of defect-induced magnetic order was found. The effect of magnetic field on the transient photoresistivity is to slow down the recombination process enhancing the photocarriers density. The experimental results demonstrate the possibility of tuning photocarriers life time using magnetic field in diluted magnetic semiconductors.

  19. Transient photocurrent and photovoltage studies on charge transport in dye sensitized solar cells made from the composites of TiO2 nanofibers and nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxu; Karanjit, Sudeep; Zhang, Lifeng; Fong, Hao; Qiao, Qiquan; Zhu, Zhengtao

    2011-02-01

    Herein, we report the transient photocurrent and photovoltage studies on the charge transport in dye sensitized solar cells (DSSCs) made from the composites of electrospun titanium oxide (TiO2) nanofibers, and conventional TiO2 nanoparticles. The results on charge transport parameters (including the charge recombination lifetime, the electron transport lifetime, and the diffusion length) indicated that the addition of TiO2 nanofibers into composite photoanodes led to substantial improvement on the efficiency of charge collection, suggesting that the composites of nanoparticles and one-dimensional nanostructures are promising materials for the development of DSSCs with high efficiency.

  20. High-density lipoproteins induce a rapid and transient release of Ca2+ in cultured fibroblasts.

    PubMed

    Pörn, M I; Akerman, K E; Slotte, J P

    1991-10-01

    Several different cell types showed increased rates of proliferation and cholesterol mobilization in response to treatment with high-density lipoprotein (HDL). This would suggest that one main function of HDL is the activation of signal pathways in cells. In the current study we have used the fluorescent indicator fura-2 to monitor the level of cytosolic Ca2+ ([Ca2+]i) in human skin fibroblasts. Exposure of subconfluent as well as confluent fibroblasts to HDL3 (20-60 micrograms/ml) resulted in a rapid and transient increase in [Ca2+]i. Sequential additions of HDL3 resulted in diminished rises in [Ca2+]i. The transient rise in [Ca2+]i was observed with HDL prepared from plasma either by conventional ultracentrifugation or by precipitation with dextran sulphate. Chelation of the extracellular Ca2+ with EGTA prior to the addition of HDL3 did not prevent the HDL3-induced rise in [Ca2+]i, suggesting that the mobilized Ca2+ was derived mainly from intracellular stores. Covalent modification of the apoproteins of HDL3 with dimethyl suberimidate or tetranitromethane did not inhibit the HDL3-induced rise in [Ca2+]i. This indicates that the binding of HDL3 to cell surface receptors may not be necessary for the mobilization of intracellular Ca2+. Moreover, the Ca(2+)-releasing effect of HDL3 was not inhibited by the presence of albumin (1%, w/v) in the extracellular medium, suggesting that non-esterified fatty acids were not the cause of the increased [Ca2+]i. The exposure of fibroblasts to lysophosphatidic acid, a potent mitogen and Ca(2+)-releasing agent, before addition of HDL3 completely inhibited the HDL3-induced rise in [Ca2+]i. Furthermore, phorbol 12-myristate 13-acetate blocked the HDL3-induced rise in [Ca2+]i. The results of this study imply that exposure of cells to HDL generates an intracellular signal which is induced by a component of the lipid fraction.

  1. Transient Expression of Candidatus Liberibacter Asiaticus Effector Induces Cell Death in Nicotiana benthamiana

    PubMed Central

    Pitino, Marco; Armstrong, Cheryl M.; Cano, Liliana M.; Duan, Yongping

    2016-01-01

    Candidatus Liberibacter asiaticus “Las” is a phloem-limited bacterial plant pathogen, and the most prevalent species of Liberibacter associated with citrus huanglongbing (HLB), a devastating disease of citrus worldwide. Although, the complete sequence of the Las genome provides the basis for studying functional genomics of Las and molecular mechanisms of Las-plant interactions, the functional characterization of Las effectors remains a slow process since remains to be cultured. Like other plant pathogens, Las may deliver effector proteins into host cells and modulate a variety of host cellular functions for their infection progression. In this study, we identified 16 putative Las effectors via bioinformatics, and transiently expressed them in Nicotiana benthamiana. Diverse subcellular localization with different shapes and aggregation patterns of the effector candidates were revealed by UV- microscopy after transient expression in leaf tissue. Intriguingly, one of the 16 candidates, Las5315mp (mature protein), was localized in the chloroplast and induced cell death at 3 days post inoculation (dpi) in N. benthamiana. Moreover, Las5315mp induced strong callose deposition in plant cells. This study provides new insights into the localizations and potential roles of these Las effectors in planta. PMID:27458468

  2. Orthogonal light-induced self-assembly of nanoparticles using differently substituted azobenzenes.

    PubMed

    Manna, Debasish; Udayabhaskararao, Thumu; Zhao, Hui; Klajn, Rafal

    2015-10-12

    Precise control of the self-assembly of selected components within complex mixtures is a challenging goal whose realization is important for fabricating novel nanomaterials. Herein we show that by decorating the surfaces of metallic nanoparticles with differently substituted azobenzenes, it is possible to modulate the wavelength of light at which the self-assembly of these nanoparticles is induced. Exposing a mixture of two types of nanoparticles, each functionalized with a different azobenzene, to UV or blue light induces the selective self-assembly of only one type of nanoparticles. Irradiation with the other wavelength triggers the disassembly of the aggregates, and the simultaneous self-assembly of nanoparticles of the other type. By placing both types of azobenzenes on the same nanoparticles, we created unique materials ("frustrated" nanoparticles) whose self-assembly is induced irrespective of the wavelength of the incident light.

  3. Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires.

    PubMed

    Li, Binsong; Wen, Xiaodong; Li, Ruipeng; Wang, Zhongwu; Clem, Paul G; Fan, Hongyou

    2014-06-24

    One-dimensional silver materials display unique optical and electrical properties with promise as functional blocks for a new generation of nanoelectronics. To date, synthetic approaches and property engineering of silver nanowires have primarily focused on chemical methods. Here we report a simple physical method of metal nanowire synthesis, based on stress-induced phase transformation and sintering of spherical Ag nanoparticle superlattices. Two phase transformations of nanoparticles under stress have been observed at distinct length scales. First, the lattice dimensions of silver nanoparticle superlattices may be reversibly manipulated between 0-8 GPa compressive stresses to enable systematic and reversible changes in mesoscale optical coupling between silver nanoparticles. Second, stresses greater than 8 GPa induced an atomic lattice phase transformation, which induced sintering of silver nanoparticles into micron-length scale nanowires. The nanowire synthesis mechanism displays a dependence on both nanoparticle crystal surface orientation and presence of particular grain boundaries to enable nanoparticle consolidation into nanowires.

  4. Transient Depletion of Kupffer Cells Leads to Enhanced Transgene Expression in Rat Liver Following Retrograde Intrabiliary Infusion of Plasmid DNA and DNA Nanoparticles

    PubMed Central

    Dai, Hui; Jiang, Xuan; Leong, Kam W.

    2011-01-01

    Abstract In this report, we have demonstrated that by temporarily removing Kupffer cells (KCs), the transgene expression levels mediated by retrograde intrabiliary infusion (RII) of plasmid DNA, polyethylenimine-DNA, and chitosan nanoparticles were enhanced by 1,927-, 131-, and 23,450-fold, respectively, in comparison with the respective groups without KC removal. KC removal also led to significantly prolonged transgene expression in the liver that received all three carriers. This increased transgene expression was correlated with significantly reduced serum tumor necrosis factor-α level as an indicator for KC activation. These results suggest that KC activation is a significant contributing factor to the lowered transgene expression by polycation-DNA nanoparticles delivered by RII. More importantly, the combination of RII and transient removal of KCs may be adopted as an effective approach to achieving high and persistent transgene expression in the liver mediated by nonviral nanoparticles. PMID:21091274

  5. Silver nanoparticles induce oocyte maturation in zebrafish (Danio rerio).

    PubMed

    Chen, Shi Xi; Yang, Xiao Zhen; Deng, Ying; Huang, Jing; Li, Yan; Sun, Qian; Yu, Chang-Ping; Zhu, Yong; Hong, Wan Shu

    2017-03-01

    Public concern regarding silver nanoparticles (AgNPs) in the environment has been increasing since they can cause adverse effects in some aquatic species. However, few data are actually available on the effects of AgNPs on the germ cells. In the present study, we used the zebrafish ovarian follicle as a model to assess the potentially adverse effects of AgNPs on oocyte maturation (germinal vesicle breakdown, GVBD) in vitro. Similar to the maturation inducing hormone (17α, 20β-dihydroxy-4-pregnen-3-one), AgNPs induced GVBD, and reduced the total cyclic adenosine monophosphate (cAMP) concentration in zebrafish ovarian follicles. The results from transmission electron microscope observation and Hoechst 33342 staining clearly indicated that AgNPs induced apoptosis in ovarian follicle cells surrounding the oocyte. Similar to AgNPs, AgNO3 also induced GVBD, decreased cAMP concentration and induced apoptosis of ovarian follicle cells. However, the results from gene expression analysis showed that transcript levels of oxidative stress related genes were more sensitive to AgNPs than AgNO3. Further more, H2O2 has an ability to induce zebrafish oocytes maturation by induction of apoptosis in ovarian follicle cells. Taken together, the results from our study indicated that oxidative stress appeared to be one of important mechanisms in AgNP induced apoptosis in ovarian follicle cells, which further triggered the GVBD.

  6. Micro-Raman Spectroscopy of Silver Nanoparticle Induced Stress on Optically-Trapped Stem Cells

    PubMed Central

    Bankapur, Aseefhali; Krishnamurthy, R. Sagar; Zachariah, Elsa; Santhosh, Chidangil; Chougule, Basavaraj; Praveen, Bhavishna; Valiathan, Manna; Mathur, Deepak

    2012-01-01

    We report here results of a single-cell Raman spectroscopy study of stress effects induced by silver nanoparticles in human mesenchymal stem cells (hMSCs). A high-sensitivity, high-resolution Raman Tweezers set-up has been used to monitor nanoparticle-induced biochemical changes in optically-trapped single cells. Our micro-Raman spectroscopic study reveals that hMSCs treated with silver nanoparticles undergo oxidative stress at doping levels in excess of 2 µg/ml, with results of a statistical analysis of Raman spectra suggesting that the induced stress becomes more dominant at nanoparticle concentration levels above 3 µg/ml. PMID:22514708

  7. Numerical Simulation of Roughness-Induced Transient Growth in a Laminar Boundary Layer

    NASA Technical Reports Server (NTRS)

    Fischer, Paul; Choudhari, Meelan

    2004-01-01

    Numerical simulations are used to examine the roughness-induced transient growth in a laminar boundary-layer flow. Based on the spectral element method, these simulations model the stationary disturbance field associated with a nonsmooth roughness geometry, such as the spanwise periodic array of circular disks used by White and co-workers during a series of wind tunnel experiments at Case Western Reserve University. Besides capturing the major trends from the recent measurements by White and Ergin, the simulations provide additional information concerning the relative accuracy of the experimental findings derived from two separate wall-finding procedures. The paper also explores the dependence of transient growth on geometric characteristics of the roughness distribution, including the height and planform shape of the roughness element and the ratio of roughness due to spacing between an adjacent pair of elements. Results are used for a preliminary assessment of the differences between recently reported theoretical results of Tumin and Reshotko and the measurements by White and Ergin.

  8. HEMP-induced transients in transmission and distribution (T and D) lines

    SciTech Connect

    Engheta, N.; Lee, K.S.H.; Yang, F.C.; Aguero, R.

    1985-09-01

    The corona effects on the early-time induced transients on the transmission and distribution (T and D) lines are calculated based on two different corona models. Three different sources of excitation of the lines are considered, which include a HEMP plane wave, a localized voltage source, and a current injected at a point on the wire. The induced current and charge are calculated and compared with some available experimental data and with the results of Baum's model. The results illustrate that the corona generally reduces the peak value of the induced current as much as 30% of the value and decreases the rate of rise by about 40%. The HEMP-induced stresses across dielectric insulators in some typical electric power systems are also calculated. The insulators that are considered are line supports in T and D line poles, and transformer bushings in distribution and power transformers. Different elevation and azimuthal angles of HEMP incidence with two different values of ground conductivity are considered. The HEMP-induced ''potential difference'' across the line support and air gap in the transmission lines and the HEMP-induced open-circuit voltage across transformer bushings are calculated. The ''potential difference'' across the line support and across the air gap can be as high as 7 MV. The rise time of the ''potential difference'' is about 110 ns, and the fall time is about 2 to 3 ..mu..s. The open-circuit voltage across transformer bushings can be as large as few tens of MVs and the rise time is in the order of 100 ns and the fall time 800 ns.

  9. Increases of Catalase and Glutathione Peroxidase Expressions by Lacosamide Pretreatment Contributes to Neuroprotection Against Experimentally Induced Transient Cerebral Ischemia.

    PubMed

    Choi, Hyun Young; Park, Joon Ha; Chen, Bai Hui; Shin, Bich Na; Lee, Yun Lyul; Kim, In Hye; Cho, Jeong-Hwi; Lee, Tae-Kyeong; Lee, Jae-Chul; Won, Moo-Ho; Ahn, Ji Hyeon; Tae, Hyun-Jin; Yan, Bing Chun; Hwang, In Koo; Cho, Jun Hwi; Kim, Young-Myeong; Kim, Sung Koo

    2016-09-01

    Lacosamide is a new antiepileptic drug which is widely used to treat partial-onset seizures. In this study, we examined the neuroprotective effect of lacosamide against transient ischemic damage and expressions of antioxidant enzymes such as Zn-superoxide dismutase (SOD1), Mn-superoxide dismutase (SOD2), catalase (CAT) and glutathione peroxidase (GPX) in the hippocampal cornu ammonis 1 (CA1) region following 5 min of transient global cerebral ischemia in gerbils. We found that pre-treatment with 25 mg/kg lacosamide protected CA1 pyramidal neurons from transient global cerebral ischemic insult using hematoxylin-eosin staining and neuronal nuclear antigen immunohistochemistry. Transient ischemia dramatically changed expressions of SOD1, SOD2 and GPX, not CAT, in the CA1 pyramidal neurons. Lacosamide pre-treatment increased expressions of CAT and GPX, not SOD1 and 2, in the CA1 pyramidal neurons compared with controls, and their expressions induced by lacosamide pre-treatment were maintained after transient cerebral ischemia. In brief, pre-treatment with lacosamide protected hippocampal CA1 pyramidal neurons from ischemic damage induced by transient global cerebral ischemia, and the lacosamide-mediated neuroprotection may be closely related to increases of CAT and GPX expressions by lacosamide pre-treatment.

  10. Photo-induced current transient spectroscopy of single crystal Tl6I4Se

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Peters, J. A.; Sebastian, M.; Kanatzidis, M. G.; Im, J.; Freeman, A. J.; Wessels, B. W.

    2014-11-01

    The compound Tl6I4Se is a promising wide band gap semiconductor for hard radiation detection at room temperature. To further improve its detection efficiency, native defects have been investigated using photo-induced current transient spectroscopy (PICTS). We observe two shallow acceptor levels with mean activation energies of 76, 175 meV, and two shallow donor defects 62, and 96 meV, respectively. No deeper donor levels are observed. The levels are attributed to native point defects. Defect capture cross sections in the range 10-21 to 10-18 cm2 were measured. The small capture cross sections are attributed to the effective screening of the defects due to a large static dielectric constant.

  11. Transient Induced Molecular Electronic Spectroscopy (TIMES) for study of protein-ligand interactions

    PubMed Central

    Zhang, Tiantian; Ku, Ti-Hsuan; Han, Yuanyuan; Subramanian, Ramkumar; Niaz, Iftikhar Ahmad; Luo, Hua; Chang, Derrick; Huang, Jian-Jang; Lo, Yu-Hwa

    2016-01-01

    We present a method, Transient Induced Molecular Electronic Spectroscopy (TIMES), to detect protein-ligand interactions without any protein engineering or chemical modification. We developed a physics model for the TIMES signal and mathematically formulated the problem to attain physical insight of protein-ligand interactions without any disturbances by molecular probes, fluorescent labels, or immobilization of molecules. To demonstrate the functionality of this method, we have used the TIMES signals to find the dissociation constants for the affinity of reactions, the shear-stress dependent adsorption time of molecules on surface, and other interesting features of protein-ligand interaction in native conditions. As a unique tool, TIMES offers a simple and effective method to investigate fundamental protein chemistry and drug discoveries. PMID:27759045

  12. Remote chlorophyll fluorescence measurements with the laser-induced fluorescence transient approach.

    PubMed

    Pieruschka, Roland; Klimov, Denis; Berry, Joseph A; Osmond, C Barry; Rascher, Uwe; Kolber, Zbigniew S

    2012-01-01

    The interaction of plants with their environment is very dynamic. Studying the underlying processes is important for understanding and modeling plant response to changing environmental conditions. Photosynthesis varies largely between different plants and at different locations within a canopy of a single plant. Thus, continuous and spatially distributed monitoring is necessary to assess the dynamic response of photosynthesis to the environment. Limited scale of observation with portable instrumentation makes it difficult to examine large numbers of plants under different environmental conditions. We report here on the application of a recently developed technique, laser-induced fluorescence transient (LIFT), for continuous remote measurement of photosynthetic efficiency of selected leaves at a distance of up to 50 m. The ability to make continuous, automatic, and remote measurements of photosynthetic efficiency of leaves with the LIFT provides a new approach for studying the interaction of plants with the environment and may become an important tool in phenotyping photosynthetic properties in field applications.

  13. Functionalized nanoparticles for AMF-induced gene and drug delivery

    NASA Astrophysics Data System (ADS)

    Biswas, Souvik

    The properties and broad applications of nano-magnetic colloids have generated much interest in recent years. Specially, Fe3O4 nanoparticles have attracted a great deal of attention since their magnetic properties can be used for hyperthermia treatment or drug targeting. For example, enhanced levels of intracellular gene delivery can be achieved using Fe3O4 nano-vectors in the presence of an external magnetic field, a process known as 'magnetofection'. The low cytotoxicity, tunable particle size, ease of surface functionalization, and ability to generate thermal energy using an external alternating magnetic field (AMF) are properties have propelled Fe3O4 research to the forefront of nanoparticle research. The strategy of nanoparticle-mediated, AMF-induced heat generation has been used to effect intracellular hyperthermia. One application of this 'magnetic hyperthermia' is heat activated local delivery of a therapeutic effector (e.g.; drug or polynucleotide). This thesis describes the development of a magnetic nano-vector for AMF-induced, heat-activated pDNA and small molecule delivery. The use of heat-inducible vectors, such as heat shock protein ( hsp) genes, is a promising mode of gene therapy that would restrict gene expression to a local region by focusing a heat stimulus only at a target region. We thus aimed to design an Fe3O4 nanoparticle-mediated gene transfer vehicle for AMF-induced localized gene expression. We opted to use 'click' oximation techniques to assemble the magnetic gene transfer vector. Chapter 2 describes the synthesis, characterization, and transfection studies of the oxime ether lipid-based nano-magnetic vectors MLP and dMLP. The synthesis and characterization of a novel series of quaternary ammonium aminooxy reagents (2.1--2.4) is described. These cationic aminooxy compounds were loaded onto nanoparticles for ligation with carbonyl groups and also to impart a net positive charge on the nanoparticle surface. Our studies indicated that the

  14. A pilot study on transient ischemic stroke induced with endothelin-1 in the rhesus monkeys

    PubMed Central

    Dai, PeiMin; Huang, Hui; Zhang, Lin; He, Jing; Zhao, XuDong; Yang, FuHan; Zhao, Ning; Yang, JianZhen; Ge, LongJiao; Lin, Yu; Yu, HuaLin; Wang, JianHong

    2017-01-01

    Endothelin-1 (ET-1), a vasoconstrictor, has recently been used to induce focal ischemia in rodents and marmoset monkeys. The rhesus monkey, however, has numerous advantages to the rodent and marmoset that make it a superior and irreplaceable animal model for studying stroke in the brain. In the present study, after mapping the preferred hand representation in two healthy male monkeys with intracortical micro-stimulation, ET-1 was microinjected into the contralateral motor cortex (M1) to its preferred hand. The monkeys had been trained in three manual dexterity tasks before the microinjection and were tested for these tasks following the ET-1 injection. Brain Magnetic Resonance Imaging scans were performed 1, 7, 14 and 28 days post ischemia. It was found that ET-1 impaired the manual dexterity of the monkeys in the vertical slot and rotating Brinkman board tasks 3–8 days after the injection. Brain imaging found that severe edema was present 7 days after the focal ischemia. This data suggest that ET-1 can induce transient ischemic stroke in rhesus monkey and that ET-1 induced focal ischemia in non-human primates is a potential model to study the mechanism of stroke and brain repair after stroke. PMID:28358140

  15. A pilot study on transient ischemic stroke induced with endothelin-1 in the rhesus monkeys.

    PubMed

    Dai, PeiMin; Huang, Hui; Zhang, Lin; He, Jing; Zhao, XuDong; Yang, FuHan; Zhao, Ning; Yang, JianZhen; Ge, LongJiao; Lin, Yu; Yu, HuaLin; Wang, JianHong

    2017-03-30

    Endothelin-1 (ET-1), a vasoconstrictor, has recently been used to induce focal ischemia in rodents and marmoset monkeys. The rhesus monkey, however, has numerous advantages to the rodent and marmoset that make it a superior and irreplaceable animal model for studying stroke in the brain. In the present study, after mapping the preferred hand representation in two healthy male monkeys with intracortical micro-stimulation, ET-1 was microinjected into the contralateral motor cortex (M1) to its preferred hand. The monkeys had been trained in three manual dexterity tasks before the microinjection and were tested for these tasks following the ET-1 injection. Brain Magnetic Resonance Imaging scans were performed 1, 7, 14 and 28 days post ischemia. It was found that ET-1 impaired the manual dexterity of the monkeys in the vertical slot and rotating Brinkman board tasks 3-8 days after the injection. Brain imaging found that severe edema was present 7 days after the focal ischemia. This data suggest that ET-1 can induce transient ischemic stroke in rhesus monkey and that ET-1 induced focal ischemia in non-human primates is a potential model to study the mechanism of stroke and brain repair after stroke.

  16. GATA1s induces hyperproliferation of eosinophil precursors in Down syndrome transient leukemia

    PubMed Central

    Maroz, Aliaksandra; Stachorski, Lena; Emmrich, Stephan; Reinhardt, Katarina; Xu, Jian; Shao, Zhen; Käbler, Sebastian; Dertmann, Tobias; Hitzler, Johann; Roberts, Irene; Vyas, Paresh; Juban, Gaetan; Hennig, Christian; Hansen, Gesine; Li, Zhe; Orkin, Stuart; Reinhardt, Dirk; Klusmann, Jan-Henning

    2014-01-01

    Transient leukemia (TL) is evident in 5–10% of all neonates with Down syndrome (DS) and associated with N-terminal truncating GATA1-mutations (GATA1s). Here we report that TL cell clones generate abundant eosinophils in a substantial fraction of patients. Sorted eosinophils from patients with TL and eosinophilia carried the same GATA1s-mutation as sorted TL-blasts, consistent with their clonal origin. TL-blasts exhibited a genetic program characteristic of eosinophils and differentiated along the eosinophil lineage in vitro. Similarly, ectopic expression of Gata1s, but not Gata1, in wild-type CD34+-hematopoietic stem and progenitor cells induced hyperproliferation of eosinophil promyelocytes in vitro. While GATA1s retained the function of GATA1 to induce eosinophil genes by occupying their promoter regions, GATA1s was impaired in its ability to repress oncogenic MYC and the pro-proliferative E2F transcription network. ChIP-seq indicated reduced GATA1s occupancy at the MYC promoter. Knockdown of MYC, or the obligate E2F-cooperation partner DP1, rescued the GATA1s-induced hyperproliferative phenotype. In agreement, terminal eosinophil maturation was blocked in Gata1Δe2 knockin mice, exclusively expressing Gata1s, leading to accumulation of eosinophil precursors in blood and bone marrow. These data suggest a direct relationship between the N-terminal truncating mutations of GATA1 and clonal eosinophilia in DS patients. PMID:24336126

  17. Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

    PubMed Central

    Wang, Liying

    2013-01-01

    The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NP-cell interaction, and immune cell activation are responsible for ROS-mediated damage. NP-induced oxidative stress responses are torch bearers for further pathophysiological effects including genotoxicity, inflammation, and fibrosis as demonstrated by activation of associated cell signaling pathways. Since oxidative stress is a key determinant of NP-induced injury, it is necessary to characterize the ROS response resulting from NP. Through physicochemical characterization and understanding of the multiple signaling cascades activated by NP-induced ROS, a systemic toxicity screen with oxidative stress as a predictive model for NP-induced injury can be developed. PMID:24027766

  18. Ultrasensitive detection of target analyte-induced aggregation of gold nanoparticles using laser-induced nanoparticle Rayleigh scattering.

    PubMed

    Lin, Jia-Hui; Tseng, Wei-Lung

    2015-01-01

    Detection of salt- and analyte-induced aggregation of gold nanoparticles (AuNPs) mostly relies on costly and bulky analytical instruments. To response this drawback, a portable, miniaturized, sensitive, and cost-effective detection technique is urgently required for rapid field detection and monitoring of target analyte via the use of AuNP-based sensor. This study combined a miniaturized spectrometer with a 532-nm laser to develop a laser-induced Rayleigh scattering technique, allowing the sensitive and selective detection of Rayleigh scattering from the aggregated AuNPs. Three AuNP-based sensing systems, including salt-, thiol- and metal ion-induced aggregation of the AuNPs, were performed to examine the sensitivity of laser-induced Rayleigh scattering technique. Salt-, thiol-, and metal ion-promoted NP aggregation were exemplified by the use of aptamer-adsorbed, fluorosurfactant-stabilized, and gallic acid-capped AuNPs for probing K(+), S-adenosylhomocysteine hydrolase-induced hydrolysis of S-adenosylhomocysteine, and Pb(2+), in sequence. Compared to the reported methods for monitoring the aggregated AuNPs, the proposed system provided distinct advantages of sensitivity. Laser-induced Rayleigh scattering technique was improved to be convenient, cheap, and portable by replacing a diode laser and a miniaturized spectrometer with a laser pointer and a smart-phone. Using this smart-phone-based detection platform, we can determine whether or not the Pb(2+) concentration exceed the maximum allowable level of Pb(2+) in drinking water.

  19. Curcumin Attenuates Hepatotoxicity Induced by Zinc Oxide Nanoparticles in Rats

    PubMed Central

    Khorsandi, Layasadat; Mansouri, Esrafil; Orazizadeh, Mahmoud; Jozi, Zahra

    2016-01-01

    Background: Zinc oxide nanoparticles (NZnO) are increasingly used in modern life. Most metal nanoparticles have adverse effects on the liver. Aims: To explore the protective action of curcumin (Cur) against hepatotoxicity induced by NZnO in rats. Study Design: Animal experimentation. Methods: Control group animals received normal saline, while the Cur group animals were treated with 200 mg/kg of Cur orally for 21 days. NZnO-intoxicated rats received 50 mg/kg of NZnO for 14 days by gavage method. In the NZnO+Cur group, rats were pretreated with Cur for 7 days before NZnO administration. Plasma activities of Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were measured as biomarkers of hepatotoxicity. Hepatic levels of malondialdehyde (MDA) and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured for detection of oxidative stress in liver tissue. Histological changes and apoptosis in liver tissue were studied by using Hematoxylin-eosin staining and the transferase dUTP nick end labeling (TUNEL) method. Results: NZnO induced a significant increase in plasma AST (2.8-fold), ALT (2.7-fold) and ALP (1.97-fold) activity in comparison to the control group (p<0.01). NZnO increased MDA content and reduced SOD and GPx activities. NZnO caused liver damage including centrilobular necrosis and microvesicular steatosis. The percentage of apoptosis in hepatocytes was increased in NZnO-treated rats (p<0.01). Pre-treatment of Cur significantly reduced lipid peroxidation (39%), increased SOD (156%) and GPx (26%) activities, and attenuated ALT (47%), AST (41%) and ALP (30%) activities. Pre-treatment with Cur also decreased the histology changes and apoptotic index of hepatocytes (p<0.05). Conclusion: These findings indicate that Cur effectively protects against NZnO-induced hepatotoxicity in rats. However, future studies are required to propose Cur as a potential protective agent against hepatotoxicity

  20. Transiently enhanced LPS-induced fever following hyperthermic stress in rabbits

    NASA Astrophysics Data System (ADS)

    Shibata, Masaaki; Uno, Tadashi; Riedel, Walter; Nishimaki, Michiyo; Watanabe, Kaori

    2005-11-01

    Hyperthermia has been shown to induce an enhanced febrile response to the bacterial-derived endotoxin lipopolysaccharide (LPS). The aim of the present study was to test the hypothesis that the enhanced LPS-induced fever seen in heat stressed (HS) animals is caused by leakage of intestinal bacterial LPS into the circulation. Male rabbits were rendered transiently hyperthermic (a maximum rectal temperature of 43°C) and divided into three groups. They were then allowed to recover in a room at 24°C for 1, 2 or 3 days post-HS. One day after injection with LPS, the post-HS rabbits exhibited significantly higher fevers than the controls, though this was not seen in rabbits at either 2 or 3 days post-HS. The plasma levels of endogenous LPS were significantly increased during the HS as compared to those seen in normothermic rabbits prior to HS. LPS fevers were not induced in these animals. One day post-HS, rabbits that had been pretreated with oral antibiotics exhibited significantly attenuated LPS levels. When challenged with human recombinant interleukin-1β instead of LPS, the 1-day post-HS rabbits did not respond with enhanced fevers. The plasma levels of TNFα increased similarly during LPS-induced fevers in both the control and 1-day post-HS rabbits, while the plasma levels of corticosterone and the osmolality of the 1-day post-HS rabbits showed no significant differences to those seen prior to the HS. These results suggest that the enhanced fever in the 1-day post-HS rabbits is LPS specific, and may be caused by increased leakage of intestinal endotoxin into blood circulation.

  1. Therapeutic effect of apatinib-loaded nanoparticles on diabetes-induced retinal vascular leakage

    PubMed Central

    Jeong, Ji Hoon; Nguyen, Hong Khanh; Lee, Jung Eun; Suh, Wonhee

    2016-01-01

    Apatinib, a novel and selective inhibitor of vascular endothelial growth factor (VEGF) receptor 2, has been demonstrated recently to exhibit anticancer efficacy by inhibiting the VEGF signaling pathway. Given the importance of VEGF in retinal vascular leakage, the present study was designed to investigate whether apatinib-loaded polymeric nanoparticles inhibit VEGF-mediated retinal vascular hyperpermeability and block diabetes-induced retinal vascular leakage. For the delivery of water-insoluble apatinib, the drug was encapsulated in nanoparticles composed of human serum albumin (HSA)-conjugated polyethylene glycol (PEG). In vitro paracellular permeability and transendothelial electric resistance assays showed that apatinib-loaded HSA-PEG (Apa-HSA-PEG) nanoparticles significantly inhibited VEGF-induced endothelial hyperpermeability in human retinal microvascular endothelial cells. In addition, they substantially reduced the VEGF-induced junctional loss and internalization of vascular endothelial-cadherin, a major component of endothelial junction complexes. In vivo intravitreal injection of Apa-HSA-PEG nanoparticles in mice blocked VEGF-induced retinal vascular leakage. These in vitro and in vivo data indicated that Apa-HSA-PEG nanoparticles efficiently blocked VEGF-induced breakdown of the blood–retinal barrier. In vivo experiments with streptozotocin-induced diabetic mice showed that an intravitreal injection of Apa-HSA-PEG nanoparticles substantially inhibited diabetes-induced retinal vascular leakage. These results demonstrated, for the first time, that apatinib-loaded nanoparticles may be a promising therapeutic agent for the prevention and treatment of diabetes-induced retinal vascular disorders. PMID:27462154

  2. Nanoparticle permeation induces water penetration, ion transport, and lipid flip-flop.

    PubMed

    Song, Bo; Yuan, Huajun; Pham, Sydney V; Jameson, Cynthia J; Murad, Sohail

    2012-12-11

    Nanoparticles are generally considered excellent candidates for targeted drug delivery. However, ion leakage and cytotoxicity induced by nanoparticle permeation is a potential problem in such drug delivery schemes because of the toxic effect of many ions. In this study, we have carried out a series of coarse-grained molecular dynamics simulations to investigate the water penetration, ion transport, and lipid molecule flip-flop in a protein-free phospholipid bilayer membrane during nanoparticle permeation. The effect of ion concentration gradient, pressure differential across the membrane, nanoparticle size, and permeation velocity have been examined in this work. Some conclusions from our studies include (1) The number of water molecules in the interior of the membrane during the nanoparticle permeation increases with the nanoparticle size and the pressure differential across the membrane but is unaffected by the nanoparticle permeation velocity or the ion concentration gradient. (2) Ion transport is sensitive to the size of nanoparticle as well as the ion concentration gradient between two sides of the membrane; no anion/cation selectivity is observed for small nanoparticle permeation, while anions are preferentially translocated through the membrane when the size of nanoparticle is large enough. (3) Incidences of lipid molecule flip-flop increases with the size of nanoparticle and ion concentration gradient and decreases with the pressure differential and the nanoparticle permeation velocity.

  3. The morphology of silver nanoparticles prepared by enzyme-induced reduction.

    PubMed

    Schneidewind, Henrik; Schüler, Thomas; Strelau, Katharina K; Weber, Karina; Cialla, Dana; Diegel, Marco; Mattheis, Roland; Berger, Andreas; Möller, Robert; Popp, Jürgen

    2012-01-01

    Silver nanoparticles were synthesized by an enzyme-induced growth process on solid substrates. In order to customize the enzymatically grown nanoparticles (EGNP) for analytical applications in biomolecular research, a detailed study was carried out concerning the time evolution of the formation of the silver nanoparticles, their morphology, and their chemical composition. Therefore, silver-nanoparticle films of different densities were investigated by using scanning as well as transmission electron microscopy to examine their structure. Cross sections of silver nanoparticles, prepared for analysis by transmission electron microscopy were additionally studied by energy-dispersive X-ray spectroscopy in order to probe their chemical composition. The surface coverage of substrates with silver nanoparticles and the maximum particle height were determined by Rutherford backscattering spectroscopy. Variations in the silver-nanoparticle films depending on the conditions during synthesis were observed. After an initial growth state the silver nanoparticles exhibit the so-called desert-rose or nanoflower-like structure. This complex nanoparticle structure is in clear contrast to the auto-catalytically grown spherical particles, which maintain their overall geometrical appearance while increasing their diameter. It is shown, that the desert-rose-like silver nanoparticles consist of single-crystalline plates of pure silver. The surface-enhanced Raman spectroscopic (SERS) activity of the EGNP structures is promising due to the exceptionally rough surface structure of the silver nanoparticles. SERS measurements of the vitamin riboflavin incubated on the silver nanoparticles are shown as an exemplary application for quantitative analysis.

  4. Upregulation of Transient Receptor Potential Canonical Channels Contributes to Endotoxin-Induced Pulmonary Arterial Stenosis

    PubMed Central

    Chen, Gui-Lan; Jiang, Hongni; Zou, Fangdong

    2016-01-01

    Background Septic shock is a pathologic condition caused by endotoxin-producing bacteria, and often associated with severe pulmonary hypertension. Inflammation is a major systemic response to endotoxin; however, it is unknown whether endotoxin has a direct impact on pulmonary arteries that contributes to pathogenesis of pulmonary hypertension. Material/Methods Rat pulmonary arteries and primary pulmonary arterial smooth muscle cells (PASMCs) were cultured in vitro and treated with lipopolysaccharide (LPS) and blockers of transient receptor potential canonical (TRPC) channels. Neointimal growth and arterial stenosis were observed on cryosections of cultured pulmonary arteries. Proliferation of PASMCs was examined by a WST-1 (water-soluble tetrazolium salt) assay. Expression of TRPC genes in pulmonary arteries and PASMCs were detected and quantified by real-time polymerase chain reaction and Western blotting. Results LPS significantly induced neointimal growth and stenosis of pulmonary arteries and promoted proliferation of PASMCs. TRPC channel blockers 2-aminoethoxydiphenyl borate and SKF-96365 inhibited LPS-induced remodeling of pulmonary arteries and PASMC proliferation. Expression of TRPC1/3/4/6 was detected in pulmonary arteries and PASMCs. LPS treatment dramatically increased the expression of TRPC3 and TRPC4 at both messenger RNA and protein levels. Conclusions LPS stimulates stenosis of pulmonary arteries through enhancement of TRPC-mediated Ca2+ entry into PASMCs, which is caused by upregulation of TRPC3 and TRPC4 channels. PMID:27471122

  5. Transient ALT activation protects human primary cells from chromosome instability induced by low chronic oxidative stress

    PubMed Central

    Coluzzi, Elisa; Buonsante, Rossella; Leone, Stefano; Asmar, Anthony J.; Miller, Kelley L.; Cimini, Daniela; Sgura, Antonella

    2017-01-01

    Cells are often subjected to the effect of reactive oxygen species (ROS) as a result of both intracellular metabolism and exposure to exogenous factors. ROS-dependent oxidative stress can induce 8-oxodG within the GGG triplet found in the G-rich human telomeric sequence (TTAGGG), making telomeres highly susceptible to ROS-induced oxidative damage. Telomeres are nucleoprotein complexes that protect the ends of linear chromosomes and their dysfunction is believed to affect a wide range of cellular and/or organismal processes. Acute oxidative stress was shown to affect telomere integrity, but how prolonged low level oxidative stress, which may be more physiologically relevant, affects telomeres is still poorly investigated. Here, we explored this issue by chronically exposing human primary fibroblasts to a low dose of hydrogen peroxide. We observed fluctuating changes in telomere length and fluctuations in the rates of chromosome instability phenotypes, such that when telomeres shortened, chromosome instability increased and when telomeres lengthened, chromosome instability decreased. We found that telomere length fluctuation is associated with transient activation of an alternative lengthening of telomere (ALT) pathway, but found no evidence of cell death, impaired proliferation, or cell cycle arrest, suggesting that ALT activation may prevent oxidative damage from reaching levels that threaten cell survival. PMID:28240303

  6. Erdosteine ameliorates lung injury induced by transient aortic occlusion in rats.

    PubMed

    Kurtoglu, Tunay; Sacar, Mustafa; Inan, Bilal Kaan; Duver, M Harun; Guler, Adem; Ucak, Alper; Us, Melih Hulusi; Yilmaz, Ahmet Turan

    2007-01-01

    The aim of this experimental study was to evaluate the protective effect of erdosteine on lung injury induced by ischaemia-reperfusion (IR) of the lower extremities of rats. Wistar albino rats (n = 21) were divided into three groups. In the IR group (n = 7), the aorta was cross-clamped for two hours, followed by one hour of reperfusion. In the erdosteine group (n = 7), animals were pretreated with erdosteine 100 mg/kg daily via gastric lavage, starting three days before aortic occlusion. In the control group (n 5 7), the lungs were removed and blood samples were taken immediately after sternotomy. No treatment was given in the control and IR groups. After both lungs were removed, biochemical parameters were measured and broncho-alveolar lavage (BAL ) assessment was made. MDA levels and MPO activities in the lung tissue were significantly reduced in the erdosteine group compared to the IR group. BAL assessment revealed decreased neutrophil counts in the erdosteine-treated group. Pretreatment of animals with erdosteine significantly attenuated transient aortic occlusion-induced remote lung injury, characterised by leukocyte accumulation and lipid peroxidation. The results suggest that erdosteine may be beneficial in amelioration of lung injury caused by IR.

  7. RADIO TRANSIENTS FROM THE ACCRETION-INDUCED COLLAPSE OF WHITE DWARFS

    SciTech Connect

    Piro, Anthony L.; Kulkarni, S. R.

    2013-01-10

    It has long been expected that in some scenarios when a white dwarf (WD) grows to the Chandrasekhar limit, it can undergo an accretion-induced collapse (AIC) to form a rapidly rotating neutron star. Nevertheless, the detection of such events has so far evaded discovery, likely because the optical, supernova-like emission is expected to be dim and short-lived. Here we propose a novel signature of AIC: a transient radio source lasting for a few months. Rapid rotation along with flux freezing and dynamo action can grow the WD's magnetic field to magnetar strengths during collapse. The spin-down of this newly born magnetar generates a pulsar wind nebula (PWN) within the {approx}10{sup -3}-10{sup -1} M{sub Sun} of ejecta surrounding it. Our calculations show that synchrotron emission from the PWN may be detectable in the radio, even if the magnetar has a rather modest magnetic field of {approx}2 Multiplication-Sign 10{sup 14} G and an initial spin period of {approx}10 ms. An all-sky survey with a detection limit of 1 mJy at 1.4 GHz would see {approx}4(f/10{sup -2}) above threshold at any given time, where f is the ratio of the AIC rate to Type Ia supernova rate. A similar scenario may result from binary neutron stars if some mergers produce massive neutron stars rather than black holes. We conclude with a discussion of the detectability of these types of transient radio sources in an era of facilities with high mapping speeds.

  8. Transcranial magnetic stimulation-induced global propagation of transient phase resetting associated with directional information flow.

    PubMed

    Kawasaki, Masahiro; Uno, Yutaka; Mori, Jumpei; Kobata, Kenji; Kitajo, Keiichi

    2014-01-01

    Electroencephalogram (EEG) phase synchronization analyses can reveal large-scale communication between distant brain areas. However, it is not possible to identify the directional information flow between distant areas using conventional phase synchronization analyses. In the present study, we applied transcranial magnetic stimulation (TMS) to the occipital area in subjects who were resting with their eyes closed, and analyzed the spatial propagation of transient TMS-induced phase resetting by using the transfer entropy (TE), to quantify the causal and directional flow of information. The time-frequency EEG analysis indicated that the theta (5 Hz) phase locking factor (PLF) reached its highest value at the distant area (the motor area in this study), with a time lag that followed the peak of the transient PLF enhancements of the TMS-targeted area at the TMS onset. Phase-preservation index (PPI) analyses demonstrated significant phase resetting at the TMS-targeted area and distant area. Moreover, the TE from the TMS-targeted area to the distant area increased clearly during the delay that followed TMS onset. Interestingly, the time lags were almost coincident between the PLF and TE results (152 vs. 165 ms), which provides strong evidence that the emergence of the delayed PLF reflects the causal information flow. Such tendencies were observed only in the higher-intensity TMS condition, and not in the lower-intensity or sham TMS conditions. Thus, TMS may manipulate large-scale causal relationships between brain areas in an intensity-dependent manner. We demonstrated that single-pulse TMS modulated global phase dynamics and directional information flow among synchronized brain networks. Therefore, our results suggest that single-pulse TMS can manipulate both incoming and outgoing information in the TMS-targeted area associated with functional changes.

  9. Gravity-induced swirl of nanoparticles in microfluidics

    PubMed Central

    Zhao, Chao; Oztekin, Alparslan

    2013-01-01

    Parallel flows of two fluids in microfluidic devices are used for miniaturized chemistry, physics, biology and bioengineering studies, and the streams are often considered to remain parallel. However, as the two fluids do not always have the same density, interface reorientation induced by density stratification is unavoidable. In this paper, flow characteristics of an aqueous polystyrene nanofluid and a sucrose-densified aqueous solution flowing parallel in microchannels are examined. Nanoparticles 100 nm in diameter are used in the study. The motion of the nanoparticles is simulated using the Lagrangian description and directly observed by a confocal microscope. Matched results are obtained from computational and empirical analysis. Although solution density homogenizes rapidly resulting from a fast diffusion of sucrose in water, the nanofluid is observed to rotate for an extended period. Angular displacement of the nanofluid depends on the ratio of gravitational force to viscous force, Re/Fr2, where Re is the Reynolds number and Fr is the Froude number. In the developing region at the steady state, the angular displacement is related to y/Dh, the ratio between distance from the inlet and the hydraulic diameter of the microfluidic channel. The development of nanofluid flow feature also depends on h/w, the ratio of microfluidic channel’s height to width. The quantitative description of the angular displacement of nanofluid will aid rational designs of microfluidic devices utilizing multistream, multiphase flows. PMID:24563612

  10. Gravity-induced swirl of nanoparticles in microfluidics.

    PubMed

    Zhao, Chao; Oztekin, Alparslan; Cheng, Xuanhong

    2013-04-01

    Parallel flows of two fluids in microfluidic devices are used for miniaturized chemistry, physics, biology and bioengineering studies, and the streams are often considered to remain parallel. However, as the two fluids do not always have the same density, interface reorientation induced by density stratification is unavoidable. In this paper, flow characteristics of an aqueous polystyrene nanofluid and a sucrose-densified aqueous solution flowing parallel in microchannels are examined. Nanoparticles 100 nm in diameter are used in the study. The motion of the nanoparticles is simulated using the Lagrangian description and directly observed by a confocal microscope. Matched results are obtained from computational and empirical analysis. Although solution density homogenizes rapidly resulting from a fast diffusion of sucrose in water, the nanofluid is observed to rotate for an extended period. Angular displacement of the nanofluid depends on the ratio of gravitational force to viscous force, Re/Fr(2), where Re is the Reynolds number and Fr is the Froude number. In the developing region at the steady state, the angular displacement is related to y/Dh, the ratio between distance from the inlet and the hydraulic diameter of the microfluidic channel. The development of nanofluid flow feature also depends on h/w, the ratio of microfluidic channel's height to width. The quantitative description of the angular displacement of nanofluid will aid rational designs of microfluidic devices utilizing multistream, multiphase flows.

  11. Real-time 1-D/2-D transient elastography on a standard ultrasound scanner using mechanically induced vibration.

    PubMed

    Azar, Reza Zahiri; Dickie, Kris; Pelissier, Laurent

    2012-10-01

    Transient elastography has been well established in the literature as a means of assessing the elasticity of soft tissue. In this technique, tissue elasticity is estimated from the study of the propagation of the transient shear waves induced by an external or internal source of vibration. Previous studies have focused mainly on custom single-element transducers and ultrafast scanners which are not available in a typical clinical setup. In this work, we report the design and implementation of a transient elastography system on a standard ultrasound scanner that enables quantitative assessment of tissue elasticity in real-time. Two new custom imaging modes are introduced that enable the system to image the axial component of the transient shear wave, in response to an externally induced vibration, in both 1-D and 2-D. Elasticity reconstruction algorithms that estimate the tissue elasticity from these transient waves are also presented. Simulation results are provided to show the advantages and limitations of the proposed system. The performance of the system is also validated experimentally using a commercial elasticity phantom.

  12. Principles of femtosecond X-ray/optical cross-correlation with X-ray induced transient optical reflectivity in solids

    SciTech Connect

    Eckert, S. E-mail: martin.beye@helmholtz-berlin.de; Beye, M. E-mail: martin.beye@helmholtz-berlin.de; Pietzsch, A.; Quevedo, W.; Hantschmann, M.; Ochmann, M.; Huse, N.; Ross, M.; Khalil, M.; Minitti, M. P.; Turner, J. J.; Moeller, S. P.; Schlotter, W. F.; Dakovski, G. L.; Föhlisch, A.

    2015-02-09

    The discovery of ultrafast X-ray induced optical reflectivity changes enabled the development of X-ray/optical cross correlation techniques at X-ray free electron lasers worldwide. We have now linked through experiment and theory the fundamental excitation and relaxation steps with the transient optical properties in finite solid samples. Therefore, we gain a thorough interpretation and an optimized detection scheme of X-ray induced changes to the refractive index and the X-ray/optical cross correlation response.

  13. Water-soluble core/shell nanoparticles for proton therapy through particle-induced radiation

    NASA Astrophysics Data System (ADS)

    Park, Jeong Chan; Jung, Myung-Hwan; Kim, Maeng Jun; Kim, Kye-Ryung

    2015-02-01

    Metallic nanoparticles have been used in biomedical applications such as magnetic resonance imaging (MRI), therapy, and drug delivery systems. Metallic nanoparticles as therapeutic tools have been demonstrated using radio-frequency magnetic fields or near-infrared light. Recently, therapeutic applications of metallic nanomaterials combined with proton beams have been reported. Particle-induced radiation from metallic nanoparticles, which can enhance the therapeutic effects of proton therapy, was released when the nanoparticles were bombarded by a high-energy proton beam. Core/shell nanoparticles, especially Au-coated magnetic nanoparticles, have drawn attention in biological applications due to their attractive characteristics. However, studies on the phase transfer of organic-ligand-based core/shell nanoparticles into water are limited. Herein, we demonstrated that hydrophobic core/shell structured nanomaterials could be successfully dispersed in water through chloroform/surfactant mixtures. The effects of the core/shell nanomaterials and the proton irradiation on Escherichia coli (E. coli) were also explored.

  14. Visualizing interfacial charge transfer in Ru-dye sensitized TiO{sub 2} nanoparticles using x-ray transient absorption spectroscopy.

    SciTech Connect

    Zhang, X.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X.

    2011-03-01

    A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru?N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

  15. Tolerogenic nanoparticles to induce immunologic tolerance: Prevention and reversal of FVIII inhibitor formation.

    PubMed

    Zhang, Ai-Hong; Rossi, Robert J; Yoon, Jeongheon; Wang, Hong; Scott, David W

    2016-03-01

    The immune response of hemophilia A patients to administered FVIII is a major complication that obviates this very therapy. We have recently described the use of synthetic, biodegradable nanoparticles carrying rapamycin and FVIII peptide antigens, to induce antigen-specific tolerance. Herein we test the tolerogenicity of nanoparticles that contains full length FVIII protein in hemophilia A mice, focusing on anti-FVIII humoral immune response. As expected, recipients of tolerogenic nanoparticles remained unresponsive to FVIII despite multiple challenges for up to 6 months. Furthermore, therapeutic treatments in FVIII-immunized mice with pre-existing anti-FVIII antibodies resulted in diminished antibody titers, albeit efficacy required longer therapy with the tolerogenic nanoparticles. Interestingly, durable FVIII-specific tolerance was also achieved in animals co-administered with FVIII admixed with nanoparticles encapsulating rapamycin alone. These results suggest that nanoparticles carrying rapamycin and FVIII can be employed to induce specific tolerance to prevent and even reverse inhibitor formation.

  16. Silver nanoparticles induce endoplasmatic reticulum stress response in zebrafish

    SciTech Connect

    Christen, Verena; Capelle, Martinus; Fent, Karl

    2013-10-15

    Silver nanoparticles (AgNPs) find increasing applications, and therefore humans and the environment are increasingly exposed to them. However, potential toxicological implications are not sufficiently known. Here we investigate effects of AgNPs (average size 120 nm) on zebrafish in vitro and in vivo, and compare them to human hepatoma cells (Huh7). AgNPs are incorporated in zebrafish liver cells (ZFL) and Huh7, and in zebrafish embryos. In ZFL cells AgNPs lead to induction of reactive oxygen species (ROS), endoplasmatic reticulum (ER) stress response, and TNF-α. Transcriptional alterations also occur in pro-apoptotic genes p53 and Bax. The transcriptional profile differed in ZFL and Huh7 cells. In ZFL cells, the ER stress marker BiP is induced, concomitant with the ER stress marker ATF-6 and spliced XBP-1 after 6 h and 24 h exposure to 0.5 g/L and 0.05 g/L AgNPs, respectively. This indicates the induction of different pathways of the ER stress response. Moreover, AgNPs induce TNF-α. In zebrafish embryos exposed to 0.01, 0.1, 1 and 5 mg/L AgNPs hatching was affected and morphological defects occurred at high concentrations. ER stress related gene transcripts BiP and Synv are significantly up-regulated after 24 h at 0.1 and 5 mg/L AgNPs. Furthermore, transcriptional alterations occurred in the pro-apoptotic genes Noxa and p21. The ER stress response was strong in ZFL cells and occurred in zebrafish embryos as well. Our data demonstrate for the first time that AgNPs lead to induction of ER stress in zebrafish. The induction of ER stress can have several consequences including the activation of apoptotic and inflammatory pathways. - Highlights: • Effects of silver nanoparticles (120 nm AgNPs) are investigated in zebrafish. • AgNPs induce all ER stress reponses in vitro in zebrafish liver cells. • AgNPs induce weak ER stress in zebrafish embryos. • AgNPs induce oxidative stress and transcripts of pro-apoptosis genes.

  17. Visible-light photoresponse of gold nanoparticles supported on TiO2 : a combined photocatalytic, photoelectrochemical, and transient spectroscopy study.

    PubMed

    Baldovi, Herme G; Albarracin, Ferran; Atienzar, Pedro; Ferrer, Belen; Alvaro, Mercedes; Garcia, Hermenegildo

    2015-02-02

    In the context of gaining understanding on the origin of the visible-light photoresponse of TiO2 containing gold nanoparticles, the photocurrent spectra and photocatalytic H2 evolution of titania (P25) and Au-P25 were compared. Whereas no photocurrent was detected upon visible-light irradiation for either of the two photocatalysts, Au-P25 exhibited photocatalytic H2 evolution for wavelengths between 400 and 575 nm. This contradictory behavior under visible-light irradiation of Au-P25 was rationalized by transient absorption spectroscopy. It was suggested that photocatalytic H2 generation results from methanol quenching of the charge-separation state in each semiconductor nanoparticle, but the lack of photocurrent is due to the short lifetime of the charge separation, which makes interparticle charge migration for micrometric distances unlikely.

  18. Surfactant-induced postsynthetic modulation of Pd nanoparticle crystallinity.

    SciTech Connect

    Liu, Y.; Wang, C.; Wei, Y.; Zhu, L.; Li, D.; Jiang, J. S.; Markovic, N. M.; Stamenkovic, V. R.; Sun, S.

    2011-02-01

    Modulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity decreases significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylamine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanocrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials.

  19. Light-induced structural phase behaviour of metal nanoparticle materials

    NASA Astrophysics Data System (ADS)

    Plech, A.; Kotaidis, V.; Wulff, M.; Dahmen, C.; von Plessen, G.

    2005-01-01

    We have investigated the structural dynamics of gold nanoparticles induced by femtosecond light excitation. Structure evolution in both embedded particles (glass matrix or liquid water suspension) and quasi-free particles adsorbed on a solid surface is analyzed. By use of stroboscopic laser pump- x-ray probe techniques the structural relaxations have been resolved on the 100 ps time scale at the European Synchrotron Radiation Facility. Several methods including powder scattering, liquid scattering and small angle scattering serve to resolve microscopic and mesoscopic length scales of the composite system. The thermal response includes the heating, lattice melting, explosive solvent evaporation and solvent cooling subsequent to the laser flash excitation. Nonthermal effects are observed with femtosecond excitation. They are attributed to ablation from the particle and particle explosion at strong nonequilibrium conditions. The observations can form a complete picture of the energy dissipation and phase transitions involved in nanoscale composites.

  20. Cerium dioxide nanoparticles do not modulate the lipopolysaccharide-induced inflammatory response in human monocytes

    PubMed Central

    Hussain, Salik; Al-Nsour, Faris; Rice, Annette B; Marshburn, Jamie; Ji, Zhaoxia; Zink, Jeffery I; Yingling, Brenda; Walker, Nigel J; Garantziotis, Stavros

    2012-01-01

    Background Cerium dioxide (CeO2) nanoparticles have potential therapeutic applications and are widely used for industrial purposes. However, the effects of these nanoparticles on primary human cells are largely unknown. The ability of nanoparticles to exacerbate pre-existing inflammatory disorders is not well documented for engineered nanoparticles, and is certainly lacking for CeO2 nanoparticles. We investigated the inflammation-modulating effects of CeO2 nanoparticles at noncytotoxic concentrations in human peripheral blood monocytes. Methods CD14+ cells were isolated from peripheral blood samples of human volunteers. Cells were exposed to either 0.5 or 1 μg/mL of CeO2 nanoparticles over a period of 24 or 48 hours with or without lipopolysaccharide (10 ng/mL) prestimulation. Modulation of the inflammatory response was studied by measuring secreted tumor necrosis factor-alpha, interleukin-1beta, macrophage chemotactic protein-1, interferon-gamma, and interferon gamma-induced protein 10. Results CeO2 nanoparticle suspensions were thoroughly characterized using dynamic light scattering analysis (194 nm hydrodynamic diameter), zeta potential analysis (−14 mV), and transmission electron microscopy (irregular-shaped particles). Transmission electron microscopy of CD14+ cells exposed to CeO2 nanoparticles revealed that these nanoparticles were efficiently internalized by monocytes and were found either in vesicles or free in the cytoplasm. However, no significant differences in secreted cytokine profiles were observed between CeO2 nanoparticle-treated cells and control cells at noncytotoxic doses. No significant effects of CeO2 nanoparticle exposure subsequent to lipopolysaccharide priming was observed on cytokine secretion. Moreover, no significant difference in lipopolysaccharide-induced cytokine production was observed after exposure to CeO2 nanoparticles followed by lipopolysaccharide exposure. Conclusion CeO2 nanoparticles at noncytotoxic concentrations neither

  1. Sequential steps underlying neuronal plasticity induced by a transient exposure to gabazine.

    PubMed

    Pegoraro, Silvia; Broccard, Frédéric D; Ruaro, Maria Elisabetta; Bianchini, Daniele; Avossa, Daniela; Pastore, Giada; Bisson, Giacomo; Altafini, Claudio; Torre, Vincent

    2010-03-01

    Periods of intense electrical activity can initiate neuronal plasticity leading to long lasting changes of network properties. By combining multielectrode extracellular recordings with DNA microarrays, we have investigated in rat hippocampal cultures the temporal sequence of events of neuronal plasticity triggered by a transient exposure to the GABA(A) receptor antagonist gabazine (GabT). GabT induced a synchronous bursting pattern of activity. The analysis of electrical activity identified three main phases during neuronal plasticity induced by GabT: (i) immediately after termination of GabT, an early synchronization (E-Sync) of the spontaneous electrical activity appears that progressively decay after 3-6 h. E-Sync is abolished by inhibitors of the ERK1/2 pathway but not by inhibitors of gene transcription; (ii) the evoked response (induced by a single pulse of extracellular electrical stimulation) was maximally potentiated 3-10 h after GabT (M-LTP); and (iii) at 24 h the spontaneous electrical activity became more synchronous (L-Sync). The genome-wide analysis identified three clusters of genes: (i) an early rise of transcription factors (Cluster 1), primarily composed by members of the EGR and Nr4a families, maximally up-regulated 1.5 h after GabT; (ii) a successive up-regulation of some hundred genes, many of which known to be involved in LTP (Cluster 2), 3 h after GabT likely underlying M-LTP. Moreover, in Cluster 2 several genes coding for K(+) channels are down-regulated at 24 h. (iii) Genes in Cluster 3 are up-regulated at 24 h and are involved in cellular homeostasis. This approach allows relating different steps of neuronal plasticity to specific transcriptional profiles.

  2. Rare earth nanoparticles prevent retinal degeneration induced by intracellular peroxides:

    NASA Astrophysics Data System (ADS)

    Chen, Junping; Patil, Swanand; Seal, Sudipta; McGinnis, James F.

    2006-11-01

    Photoreceptor cells are incessantly bombarded with photons of light, which, along with the cells' high rate of oxygen metabolism, continuously exposes them to elevated levels of toxic reactive oxygen intermediates (ROIs). Vacancy-engineered mixed-valence-state cerium oxide nanoparticles (nanoceria particles) scavenge ROIs. Our data show that nanoceria particles prevent increases in the intracellular concentrations of ROIs in primary cell cultures of rat retina and, in vivo, prevent loss of vision due to light-induced degeneration of photoreceptor cells. These data indicate that the nanoceria particles may be effective in inhibiting the progression of ROI-induced cell death, which is thought to be involved in macular degeneration, retinitis pigmentosa and other blinding diseases, as well as the ROI-induced death of other cell types in diabetes, Alzheimer's disease, atherosclerosis, stroke and so on. The use of nanoceria particles as a direct therapy for multiple diseases represents a novel strategy and suggests that they may represent a unique platform technology.

  3. Dynamic Response in Transient Stress-Field Behavior Induced by Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Jenkins, Andrew

    magnitude. These types of shifts are of great concern because they can impact subsequent fracture development causing non-uniform fracture propagation and the potential overlapping of fracture paths as they extend from the wellbore at the point of injection. The dynamics of stress variation that occur with respect to hydraulic fracturing is a somewhat new area of study. In order to accomplish the goals of this thesis and continue future research in this area a new transient model has been developed in order to asses these dynamic systems and determine their influence on fracture behavior. This applies the use of a fully coupled finite element method in 2-D using linear elastic fracture mechanics which is then expanded using displacement discontinuity to a cohesive zone model in 3-D. A static boundary element model was also used to determine stress fields surrounding static, predetermined fracture geometries. These models have been verified against analytical solutions for simple cases and are now being applied to more detailed case studies and analysis. These models have been briefly discussed throughout this thesis in order to give insight on their current capabilities and application as well as their future potential within this area of research. The majority of this work introduces transient stress field prediction to cases of single and multiple hydraulic fractures. The static assessment of these stresses is determined for verification of results to those found in publication which leads into these transient stress field variations. A new method has been developed and applied to the stress state prediction for the first time in a transient fracture model which is partly based upon a critical distance theory. These dynamic interactions can provide useful insight to pertinent issues within the petroleum and natural gas industry such as those to hydraulic fracturing fluid loss and induced seismic events, as well as to applications of efficiency and optimization of the

  4. Transient Plasma Induced Production of OH and its Effects on Ignition in Atmospheric CH4-AIR Quiescent Mixtures (Postprint)

    DTIC Science & Technology

    2008-01-01

    Sinibaldi, C. Brophy, J. Hoke, F. Schauer, J. Corrigan , J. Yu, E. Barbour, and R. Hanson, “Transient Plasma Ignition for Delay Reduction in Pulse Detonation...contains color. PAO Case Number: WPAFB 07-0549, 29 Nov 2007. 14. ABSTRACT Transient plasma from a 60 kV, 70 ns pulse induced OH production in air...quiescent mixtures inside a cylindrical chamber. The chamber is filled with ambient air or a CH4/dry-air mixture, and a 60 kV electrical pulse 70 ns

  5. Digital system upset. The effects of simulated lightning-induced transients on a general-purpose microprocessor

    NASA Technical Reports Server (NTRS)

    Belcastro, C. M.

    1983-01-01

    Flight critical computer based control systems designed for advanced aircraft must exhibit ultrareliable performance in lightning charged environments. Digital system upset can occur as a result of lightning induced electrical transients, and a methodology was developed to test specific digital systems for upset susceptibility. Initial upset data indicates that there are several distinct upset modes and that the occurrence of upset is related to the relative synchronization of the transient input with the processing sate of the digital system. A large upset test data base will aid in the formulation and verification of analytical upset reliability modeling techniques which are being developed.

  6. Cerium Oxide Nanoparticles Induce Oxidative Stress and Genotoxicity in Human Skin Melanoma Cells.

    PubMed

    Ali, Daoud; Alarifi, Saud; Alkahtani, Saad; AlKahtane, Abdullah A; Almalik, Abdulaziz

    2015-04-01

    Extensive applications of cerium oxide (CeO2) nanoparticles require a better understanding of their possible effects on human health. However, data demonstrating the effect of CeO2 nanoparticles on the human skin melanoma cell remain scanty. In the current study, we determined the mechanism through which CeO2 nanoparticles (APS <25 nm) induce toxicity in human skin melanoma cells (A375). The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and neutral red uptake assays showed concentration and time-dependent cytotoxicity of CeO2 nanoparticles in A375 cells. CeO2 nanoparticles significantly induced the generation reactive oxygen species (ROS) and malondialdehyde, superoxide dismutase, and decreased glutathione levels in A375 cells. It was also observed that the CeO2 nanoparticles induced chromosomal condensation and caspase-3 activity. CeO2 nanoparticles exposed cells revealed the formation of DNA double-strand breakage as measured by percent tail DNA and olive tail moment through comet assay. The decline of cell viability, production of ROS, and DNA damage in A375 cells specifies that CeO2 nanoparticles have less capable to induce cyto and genotoxicity.

  7. Leukocyte transepithelial migration in lung induced by DMSA functionalized magnetic nanoparticles.

    PubMed

    Azevedo, Ricardo Bentes; Valois, Caroline Rodrigues Alves; Chaves, Sacha Braun; Silva, Jaqueline Rodrigues; Garcia, Monica Pereira

    2011-01-01

    Magnetic nanoparticles surface-covered with meso-2,3-dimercaptosuccinic acid (MNPs-DMSA) constitute a promising approach for tissue- and cell-targeted delivery of therapeutic drugs in the lung. However, they can also induce a transient transendothelial migration of leukocytes in the organ as a side effect after endovenous administration of MNPs-DMSA. We demonstrated that monocytes/macrophages constitute the main subpopulation of leukocytes involved in this process. Our recent research found that MNPs-DMSA up-regulated the mRNA expression of E-, L- and P-selectin and macrophage-1 antigen, and increased concentration of tumor necrosis factor-α in lung, in a time dependent manner. The critical relevance of the β2 integrin-dependent pathway in leukocyte transmigration elicited by MNPs-DMSA was demonstrated by use of knockout mice. Our work characterizes mechanisms of the pro-inflammatory effects of MNPs-DMSA in the lung, and identifies β2 integrin-targeted interventions as promising strategies to reduce pulmonary side effects of MNPs-DMSA during biomedical applications. In addition, MNPs-DMSA could be used as modulators of lung immune response.

  8. Kindling induces transient fast inhibition in the dentate gyrus--CA3 projection.

    PubMed

    Gutiérrez, R; Heinemann, U

    2001-04-01

    The granule cells of the dentate gyrus (DG) send a strong glutamatergic projection, the mossy fibre tract, toward the hippocampal CA3 field, where it excites pyramidal cells and neighbouring inhibitory interneurons. Despite their excitatory nature, granule cells contain small amounts of GAD (glutamate decarboxylase), the main synthetic enzyme for the inhibitory transmitter GABA. Chronic temporal lobe epilepsy results in transient upregulation of GAD and GABA in granule cells, giving rise to the speculation that following overexcitation, mossy fibres exert an inhibitory effect by release of GABA. We therefore stimulated the DG and recorded synaptic potentials from CA3 pyramidal cells in brain slices from kindled and control rats. In both preparations, DG stimulation caused excitatory postsynaptic potential (EPSP)/inhibitory postsynaptic potential (IPSP) sequences. These potentials could be completely blocked by glutamate receptor antagonists in control rats, while in the kindled rats, a bicuculline-sensitive fast IPSP remained, with an onset latency similar to that of the control EPSP. Interestingly, this IPSP disappeared 1 month after the last seizure. When synaptic responses were evoked by high-frequency stimulation, EPSPs in normal rats readily summate to evoke action potentials. In slices from kindled rats, a summation of IPSPs overrides that of the EPSPs and reduces the probability of evoking action potentials. Our data show for the first time that kindling induces functionally relevant activity-dependent expression of fast inhibition onto pyramidal cells, coming from the DG, that can limit CA3 excitation in a frequency-dependent manner.

  9. Line-edge roughness induced single event transient variation in SOI FinFETs

    NASA Astrophysics Data System (ADS)

    Weikang, Wu; Xia, An; Xiaobo, Jiang; Yehua, Chen; Jingjing, Liu; Xing, Zhang; Ru, Huang

    2015-11-01

    The impact of process induced variation on the response of SOI FinFET to heavy ion irradiation is studied through 3-D TCAD simulation for the first time. When FinFET biased at OFF state configuration (Vgs = 0, Vds = Vdd) is struck by a heavy ion, the drain collects ionizing charges under the electric field and a current pulse (single event transient, SET) is consequently formed. The results reveal that with the presence of line-edge roughness (LER), which is one of the major variation sources in nano-scale FinFETs, the device-to-device variation in terms of SET is observed. In this study, three types of LER are considered: type A has symmetric fin edges, type B has irrelevant fin edges and type C has parallel fin edges. The results show that type A devices have the largest SET variation while type C devices have the smallest variation. Further, the impact of the two main LER parameters, correlation length and root mean square amplitude, on SET variation is discussed as well. The results indicate that variation may be a concern in radiation effects with the down scaling of feature size.

  10. Rapamycin transiently induces mitochondrial remodeling to reprogram energy metabolism in old hearts

    PubMed Central

    Chiao, Ying Ann; Kolwicz, Stephen C.; Basisty, Nathan; Gagnidze, Arni; Zhang, Julia; Gu, Haiwei; Djukovic, Danijel; Beyer, Richard P.; Raftery, Daniel; MacCoss, Michael; Tian, Rong; Rabinovitch, Peter S.

    2016-01-01

    Rapamycin, an inhibitor of mTOR signaling, has been shown to reverse diastolic dysfunction in old mice in 10 weeks, highlighting its therapeutic potential for a poorly treatable condition. However, the mechanisms and temporal regulation of its cardiac benefits remain unclear. We show that improved diastolic function in old mice begins at 2-4 weeks, progressing over the course of 10-week treatment. While TORC1-mediated S6 phosphorylation and TORC2 mediated AKT and PKCα phosphorylation are inhibited throughout the course of treatment, rapamycin inhibits ULK phosphorylation and induces autophagy during just the first week of treatment, returning to baseline at two weeks and after. Concordantly, markers of mitochondrial biogenesis increase over the first two weeks of treatment and return to control levels thereafter. This transient induction of autophagy and mitochondrial biogenesis suggests that damaged mitochondria are replaced by newly synthesized ones to rejuvenate mitochondrial homeostasis. This remodeling is shown to rapidly reverse the age-related reduction in fatty acid oxidation to restore a more youthful substrate utilization and energetic profile in old isolated perfused hearts, and modulates the myocardial metabolome in vivo. This study demonstrates the differential and dynamic mechanisms following rapamycin treatment and highlights the importance of understanding the temporal regulation of rapamycin effects. PMID:26872208

  11. Thermal transport in suspended silicon membranes measured by laser-induced transient gratings

    NASA Astrophysics Data System (ADS)

    Vega-Flick, A.; Duncan, R. A.; Eliason, J. K.; Cuffe, J.; Johnson, J. A.; Peraud, J.-P. M.; Zeng, L.; Lu, Z.; Maznev, A. A.; Wang, E. N.; Alvarado-Gil, J. J.; Sledzinska, M.; Sotomayor Torres, C. M.; Chen, G.; Nelson, K. A.

    2016-12-01

    Studying thermal transport at the nanoscale poses formidable experimental challenges due both to the physics of the measurement process and to the issues of accuracy and reproducibility. The laser-induced transient thermal grating (TTG) technique permits non-contact measurements on nanostructured samples without a need for metal heaters or any other extraneous structures, offering the advantage of inherently high absolute accuracy. We present a review of recent studies of thermal transport in nanoscale silicon membranes using the TTG technique. An overview of the methodology, including an analysis of measurements errors, is followed by a discussion of new findings obtained from measurements on both "solid" and nanopatterned membranes. The most important results have been a direct observation of non-diffusive phonon-mediated transport at room temperature and measurements of thickness-dependent thermal conductivity of suspended membranes across a wide thickness range, showing good agreement with first-principles-based theory assuming diffuse scattering at the boundaries. Measurements on a membrane with a periodic pattern of nanosized holes (135nm) indicated fully diffusive transport and yielded thermal diffusivity values in agreement with Monte Carlo simulations. Based on the results obtained to-date, we conclude that room-temperature thermal transport in membrane-based silicon nanostructures is now reasonably well understood.

  12. Transient land breeze: Eclipse induced wind flow modifications—Observations over plant canopy

    NASA Astrophysics Data System (ADS)

    Murthy, B. S.; Latha, R.; Sreeja, P.; Dharmaraj, T.

    2012-11-01

    An experiment is conducted over Cassava plant canopy at a coastal station at CTCRI, Thiruvananthapuram (8°29'N, 76°59E) to study the response of meteorological parameters and land-sea breeze circulations to the annular solar eclipse on January 15, 2010. Observations reveal decrease of solar radiation to a minimum of 96 W m-2 during the peak eclipse period. Air temperature drops by 4 °C and relative humidity increases by 20%. Sensible heat flux reduces to zero. Transient land breeze occurs for a few minutes with a time lag of about 1 h possibly due to outflow from the umbra region or temperature gradient over land with the eclipse progressing in the eastward direction. Sea breeze is delayed by about 3 h on the next day of eclipse. Spectral energy density of wind (u, v, w) and temperature attains a minimum value during totality and increases later, attributable to reduction in turbulence due to eclipse-induced stability.

  13. Cerebrovascular adaptations to cocaine-induced transient ischemic attacks in the rodent brain

    PubMed Central

    You, Jiang; Volkow, Nora D.; Park, Kicheon; Zhang, Qiujia; Clare, Kevin; Du, Congwu

    2017-01-01

    Occurrence of transient ischemic attacks (TIA) and cerebral strokes is a recognized risk associated with cocaine abuse. Here, we use a rodent model along with optical imaging to study cocaine-induced TIA and the associated dynamic changes in cerebral blood flow velocity (CBFv) and cerebrovasculature. We show that chronic cocaine exposure in mice resulted in marked cortical hypoperfusion, in significant arterial and venous vasoconstriction, and in a sensitized vascular response to an acute cocaine injection. Starting after 10 days of exposure, an acute cocaine challenge to these mice resulted in a TIA, which presented as hemiparalysis and was associated with an abrupt exacerbation of CBFv. The severity of the TIA correlated with the decreases in cortical CBFv such that the greater the decreases in flow, the longer the TIA duration. The severity of TIA peaked around 17–22 days of cocaine exposure and decreased thereafter in parallel to a reorganization of CBFv from superficial to deep cortical layers, along with an increase in vessel density into these layers. Here, we document for the first time to our knowledge evidence of a TIA in an animal model of chronic cocaine exposure that was associated with profound decreases in CBFv, and we revealed that while the severity of the TIA initially increased with repeated exposures, it subsequently improved in parallel to an increase in the vessel density. This suggests that strategies to accelerate cerebrovascular recovery might be therapeutically beneficial in cocaine abusers. PMID:28289715

  14. Repetitive Transient Depolarizations of the Inner Mitochondrial Membrane Induced by Proton Pumping

    PubMed Central

    Hattori, Tomohiro; Watanabe, Koichi; Uechi, Yukiko; Yoshioka, Hisashi; Ohta, Yoshihiro

    2005-01-01

    Single mitochondria show the spontaneous fluctuations of ΔΨm. In this study, to examine the mechanism of the fluctuations, we observed ΔΨm in single isolated heart mitochondria using time-resolved fluorescence microscopy. Addition of malate, succinate, or ascorbate plus TMPD to mitochondria induced polarization of the inner membrane followed by repeated cycles of rapid depolarizations and immediate repolarizations. ADP significantly decreased the frequency of the rapid depolarizations, but the ADP effect was counteracted by oligomycin. On the other hand, the rapid depolarizations did not occur when mitochondria were polarized by the efflux of K+ from the matrix. The rapid depolarizations became frequent with the increase in the substrate concentration or pH of the buffer. These results suggest that the rapid depolarizations depend on the net translocation of protons from the matrix. The frequency of the rapid depolarizations was not affected by ROS scavengers, Ca2+, CsA, or BA. In addition, the obvious increase in the permeability of the inner membrane to calcein (MW 623) that was entrapped in the matrix was not observed upon the transient depolarization. The mechanisms of the spontaneous oscillations of ΔΨm are discussed in relation to the matrix pH and the permeability transitions. PMID:15653749

  15. IP3-dependent, post-tetanic calcium transients induced by electrostimulation of adult skeletal muscle fibers

    PubMed Central

    Casas, Mariana; Figueroa, Reinaldo; Jorquera, Gonzalo; Escobar, Matías; Molgó, Jordi

    2010-01-01

    Tetanic electrical stimulation induces two separate calcium signals in rat skeletal myotubes, a fast one, dependent on Cav 1.1 or dihydropyridine receptors (DHPRs) and ryanodine receptors and related to contraction, and a slow signal, dependent on DHPR and inositol trisphosphate receptors (IP3Rs) and related to transcriptional events. We searched for slow calcium signals in adult muscle fibers using isolated adult flexor digitorum brevis fibers from 5–7-wk-old mice, loaded with fluo-3. When stimulated with trains of 0.3-ms pulses at various frequencies, cells responded with a fast calcium signal associated with muscle contraction, followed by a slower signal similar to one previously described in cultured myotubes. Nifedipine inhibited the slow signal more effectively than the fast one, suggesting a role for DHPR in its onset. The IP3R inhibitors Xestospongin B or C (5 µM) also inhibited it. The amplitude of post-tetanic calcium transients depends on both tetanus frequency and duration, having a maximum at 10–20 Hz. At this stimulation frequency, an increase of the slow isoform of troponin I mRNA was detected, while the fast isoform of this gene was inhibited. All three IP3R isoforms were present in adult muscle. IP3R-1 was differentially expressed in different types of muscle fibers, being higher in a subset of fast-type fibers. Interestingly, isolated fibers from the slow soleus muscle did not reveal the slow calcium signal induced by electrical stimulus. These results support the idea that IP3R-dependent slow calcium signals may be characteristic of distinct types of muscle fibers and may participate in the activation of specific transcriptional programs of slow and fast phenotype. PMID:20837675

  16. Parathyroid Hormone (1-34) Transiently Protects Against Radiation-Induced Bone Fragility.

    PubMed

    Oest, Megan E; Mann, Kenneth A; Zimmerman, Nicholas D; Damron, Timothy A

    2016-06-01

    Radiation therapy for soft tissue sarcoma or tumor metastases is frequently associated with damage to the underlying bone. Using a mouse model of limited field hindlimb irradiation, we assessed the ability of parathyroid hormone (1-34) fragment (PTH) delivery to prevent radiation-associated bone damage, including loss of mechanical strength, trabecular architecture, cortical bone volume, and mineral density. Female BALB/cJ mice received four consecutive doses of 5 Gy to a single hindlimb, accompanied by daily injections of either PTH or saline (vehicle) for 8 weeks, and were followed for 26 weeks. Treatment with PTH maintained the mechanical strength of irradiated femurs in axial compression for the first eight weeks of the study, and the apparent strength of irradiated femurs in PTH-treated mice was greater than that of naïve bones during this time. PTH similarly protected against radiation-accelerated resorption of trabecular bone and transient decrease in mid-diaphyseal cortical bone volume, although this benefit was maintained only for the duration of PTH delivery. Overall, PTH conferred protection against radiation-induced fragility and morphologic changes by increasing the quantity of bone, but only during the period of administration. Following cessation of PTH delivery, bone strength and trabecular volume fraction rapidly decreased. These data suggest that PTH does not negate the longer-term potential for osteoclastic bone resorption, and therefore, finite-duration treatment with PTH alone may not be sufficient to prevent late onset radiotherapy-induced bone fragility.

  17. Transient Receptor Potential Melastatin 7 Cation Channel Kinase: New Player in Angiotensin II-Induced Hypertension.

    PubMed

    Antunes, Tayze T; Callera, Glaucia E; He, Ying; Yogi, Alvaro; Ryazanov, Alexey G; Ryazanova, Lillia V; Zhai, Alexander; Stewart, Duncan J; Shrier, Alvin; Touyz, Rhian M

    2016-04-01

    Transient receptor potential melastatin 7 (TRPM7) is a bifunctional protein comprising a magnesium (Mg(2+))/cation channel and a kinase domain. We previously demonstrated that vasoactive agents regulate vascular TRPM7. Whether TRPM7 plays a role in the pathophysiology of hypertension and associated cardiovascular dysfunction is unknown. We studied TRPM7 kinase-deficient mice (TRPM7Δkinase; heterozygous for TRPM7 kinase) and wild-type (WT) mice infused with angiotensin II (Ang II; 400 ng/kg per minute, 4 weeks). TRPM7 kinase expression was lower in heart and aorta from TRPM7Δkinase versus WT mice, effects that were further reduced by Ang II infusion. Plasma Mg(2+) was lower in TRPM7Δkinase versus WT mice in basal and stimulated conditions. Ang II increased blood pressure in both strains with exaggerated responses in TRPM7Δkinase versus WT groups (P<0.05). Acetylcholine-induced vasorelaxation was reduced in Ang II-infused TRPM7Δkinase mice, an effect associated with Akt and endothelial nitric oxide synthase downregulation. Vascular cell adhesion molecule-1 expression was increased in Ang II-infused TRPM7 kinase-deficient mice. TRPM7 kinase targets, calpain, and annexin-1, were activated by Ang II in WT but not in TRPM7Δkinase mice. Echocardiographic and histopathologic analysis demonstrated cardiac hypertrophy and left ventricular dysfunction in Ang II-treated groups. In TRPM7 kinase-deficient mice, Ang II-induced cardiac functional and structural effects were amplified compared with WT counterparts. Our data demonstrate that in TRPM7Δkinase mice, Ang II-induced hypertension is exaggerated, cardiac remodeling and left ventricular dysfunction are amplified, and endothelial function is impaired. These processes are associated with hypomagnesemia, blunted TRPM7 kinase expression/signaling, endothelial nitric oxide synthase downregulation, and proinflammatory vascular responses. Our findings identify TRPM7 kinase as a novel player in Ang II-induced hypertension

  18. Radiation-Induced Transient Effects in Near Infrared Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Pickel, J.; Marshall, P.; Waczynski, A.; McMurray, R.; Gee, G.; Polidan, E.; Johnson, S.; McKeivey, M.; Ennico, K.; Johnson, R.

    2004-01-01

    This viewgraph presentation describes a test simulate the transient effects of cosmic ray impacts on near infrared focal plane arrays. The objectives of the test are to: 1) Characterize proton single events as function of energy and angle of incidence; 2) Measure charge spread (crosstalk) to adjacent pixels; 3) Assess transient recovery time.

  19. Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles.

    PubMed

    Alabastri, Alessandro; Yang, Xiao; Manjavacas, Alejandro; Everitt, Henry O; Nordlander, Peter

    2016-04-26

    The intense local field induced near metallic nanostructures provides strong enhancements for surface-enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we consider that plasmonic nanoparticles can also induce remarkably large electromagnetic field gradients near their surfaces. Sizeable field gradients can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. Specifically, we investigate how the local field gradients near metallic nanostructures depend on geometry, polarization, and wavelength. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. This quantity, based on integrated fields rather than field gradients, is particularly well-suited for optimization using numerical grid-based full wave electromagnetic simulations. The LAM vector has a more compact structure than the gradient matrix and can be straightforwardly associated with the angular momentum of the electromagnetic field incident on the plasmonic structures.

  20. Mechanisms of silver_nanoparticles induced hypopigmentation in embryonic zebrafish.

    PubMed

    Xu, Lian; Xu, Qin-Han; Zhou, Xin-Ying; Yin, Li-Yan; Guan, Peng-Peng; Zhang, Ting; Liu, Jing-Xia

    2017-03-01

    Silver_nanoparticles (AgNPs) have been reported to inhibit specification of erythroid cells and to induce spinal cord deformities and cardiac arrhythmia in vertebrates, but have not been implicated in development of neural crest (NC) and pigment cells in an in vivo model yet. In current study, down-regulated expressions of NC genes pax7 and foxd3, melanophore genes mitfa and dct, and xanthophore gene gch2 in AgNPs-exposed embryos were revealed by microarray, qRT-PCR and whole-mount in situ hybridization (WISH). Then, the down-regulated expressions of melanophore genes mitfa and dct but not xanthophore gene gch2 in AgNPs-exposed embryos were found to be recovered by melanogenesis agonists palmitic acid and dibutyryl cyclic AMP (dbcAMP). Finally, Ag(+) chelating and AgNPs coating compound l-cysteine was found to neutralize AgNPs-induced hypopigmentation in AgNPs-exposed embryos, and to recover the down-regulated expressions of both dct and gch2 to nearly normal level in embryos, suggesting that AgNPs-releasing Ag(+) might mediate their biological effects on zebrafish pigmentation mostly. This study was firstly to unveil that AgNPs might specifically act up-stream of mitfa and pax7 genes to suppress specification and differentiation of melanophore and xanthophore lineages respectively by their releasing Ag(+) during vertebrate embryogenesis.

  1. Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

    EPA Science Inventory

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe res...

  2. Silver nanoparticles-induced cytotoxicity requires ERK activation in human bladder carcinoma cells.

    PubMed

    Castiglioni, Sara; Cazzaniga, Alessandra; Perrotta, Cristiana; Maier, Jeanette A M

    2015-09-17

    Silver nanoparticles are toxic both in vitro and in vivo. We have investigated the possibility to exploit the cytotoxic potential of silver nanoparticles in T24 bladder carcinoma cells using both bare and PolyVinylPyrrolidone-coated silver nanoparticles. We show that the two types of silver nanoparticles promote morphological changes and cytoskeletal disorganization, are cytotoxic and induce cell death. These effects are due to the increased production of reactive oxygen species which are responsible, at least in part, for the sustained activation of ERK1/2. Indeed, both cytotoxicity and ERK1/2 activation are prevented by exposing the cells to the anti-oxidant N-acetylcysteine. Also blocking the ERK1/2 pathway with the MEK inhibitor PD98059 protects the cells from nanoparticles' cytotoxicity. Our findings suggest that ERK activation plays a role in silver nanoparticle-mediated cytotoxicity in T24 cells.

  3. Micelle depletion-induced vs. micelle-mediated aggregation in nanoparticles

    SciTech Connect

    Ray, D. Aswal, V. K.

    2015-06-24

    The phase behavior anionic silica nanoparticle (Ludox LS30) with non-ionic surfactants decaethylene glycol monododecylether (C12E10) and cationic dodecyltrimethyl ammonium bromide (DTAB) in aqueous electrolyte solution has been studied by small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations of nanoparticle (1 wt%), surfactants (1 wt%) and electrolyte (0.1 M NaCl). Each of these nanoparticle–surfactant systems has been examined for different contrast conditions where individual components (nanoparticle or surfactant) are made visible. It is observed that the nanoparticle-micelle system in both the cases lead to the aggregation of nanoparticles. The aggregation is found to be micelle depletion-induced for C12E10 whereas micelle-mediated aggregation for DTAB. Interestingly, it is also found that phase behavior of mixed surfactant (C12E10 + DTAB) system is similar to that of C12E10 (unlike DTAB) micelles with nanoparticles.

  4. Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy

    NASA Astrophysics Data System (ADS)

    Tamarov, Konstantin P.; Osminkina, Liubov A.; Zinovyev, Sergey V.; Maximova, Ksenia A.; Kargina, Julia V.; Gongalsky, Maxim B.; Ryabchikov, Yury; Al-Kattan, Ahmed; Sviridov, Andrey P.; Sentis, Marc; Ivanov, Andrey V.; Nikiforov, Vladimir N.; Kabashin, Andrei V.; Timoshenko, Victor Yu

    2014-11-01

    Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1-5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

  5. Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy.

    PubMed

    Tamarov, Konstantin P; Osminkina, Liubov A; Zinovyev, Sergey V; Maximova, Ksenia A; Kargina, Julia V; Gongalsky, Maxim B; Ryabchikov, Yury; Al-Kattan, Ahmed; Sviridov, Andrey P; Sentis, Marc; Ivanov, Andrey V; Nikiforov, Vladimir N; Kabashin, Andrei V; Timoshenko, Victor Yu

    2014-11-13

    Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50 °C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1-5 W/cm(2)). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

  6. Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy

    PubMed Central

    Tamarov, Konstantin P.; Osminkina, Liubov A.; Zinovyev, Sergey V.; Maximova, Ksenia A.; Kargina, Julia V.; Gongalsky, Maxim B.; Ryabchikov, Yury; Al-Kattan, Ahmed; Sviridov, Andrey P.; Sentis, Marc; Ivanov, Andrey V.; Nikiforov, Vladimir N.; Kabashin, Andrei V.; Timoshenko, Victor Yu

    2014-01-01

    Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1–5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy. PMID:25391603

  7. Voltage-clamp studies of transient inward current and mechanical oscillations induced by ouabain in ferret papillary muscle.

    PubMed

    Karagueuzian, H S; Katzung, B G

    1982-06-01

    1. We studied the effects of a toxic concentration of ouabain on transmembrane electrical activity and on mechanical behaviour of right ventricular papillary muscles from ferrets in a single sucrose-gap using current clamp and voltage clamp.2. Ouabain (1.4-1.8 muM) induced oscillatory after-potentials and after-concentrations in current-clamp experiments. Voltage clamp showed that the oscillatory after-potential was caused by a transient inward current, similar to that in Purkinje fibres.3. The transient current had a sigmoidal dependence on the preceding (activating) voltage step V1, with a treshold around -13 mV and a plateau between +10 and 20 mV. There was a decline in current amplitude for more positive clamps. When activated by a fixed V1 voltage step, and measured at different repolarization levels V2, the transient current manifested an inverse dependence on V2 between -50 and -10 mV. No outward transient current could be detected. Total replacement of Na in the bathing medium by Tris or by sucrose abolished the transient current.4. Ouabain caused an increase of phasic (twitch) tension responses to voltage steps at all potentials without shifting the curve relating these variables on the voltage axis. The drug evoked an even greater increase in the tonic tension responses.5. After prolonged exposure, oscillatory mechanical responses were frequently recorded during positive voltage steps. Unlike the after-contraction, these mechanical fluctuations were not consistently damped and were not accompanied by detectable synchronous current fluctuations. Catecholamines and dibutyryl cyclic AMP markedly reduced the amplitude of the tonic contraction and the mechanical oscillations but increased their frequency. Caffeine had no effect on the tonic contraction amplitude but abolished the fluctuations.6. These results support the proposal that Ca is transiently released from the overloaded sarcoplasmic reticulum in ouabain-intoxicated muscle and may evoke oscillatory

  8. Heavy Ion Microbeam- and Broadbeam-Induced Current Transients in SiGe HBTs

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Reed, R. A.; McMorrow, D.; Vizkelethy, G.; Ferlet-Cavrois, V.; Baggio, J.; Duhamel, O.; Moen, K. A.; Phillips, S. D.; Diestelhorst, R. M.; Cressler, J. D.; Sutton, A. K.; Raman, A.; Turowski, M.; Dodd, P. E.; Alles, M. L.; Schrimpf, R. D.; Marshall, P. W.; Labeal, K. A.

    2009-01-01

    IBM 5AM SiGe HBT is device-under-test. High-speed measurement setup. Low-impedance current transient measurements. SNL, JYFL, GANIL. Microbeam to broadbeam position inference. Improvement to state-of-the-art. Microbeam (SNL) transients reveal position dependent heavy ion response, Unique response for different device regions Unique response for different bias schemes. Similarities to TPA pulsed-laser data. Broadbeam transients (JYFL and GANIL) provide realistic heavy ion response. Feedback using microbeam data. Overcome issues of LET and ion range with microbeam. **Angled Ar-40 data in full paper. Data sets yield first-order results, suitable for TCAD calibration feedback.

  9. A factor from Trypanosoma cruzi induces repetitive cytosolic free Ca2+ transients in isolated primary canine cardiac myocytes.

    PubMed Central

    Barr, S C; Han, W; Andrews, N W; Lopez, J W; Ball, B A; Pannabecker, T L; Gilmour, R F

    1996-01-01

    An unusual 120-kDa alkaline peptidase contained in a trypomastigote soluble fraction (TSF) of Trypanosoma cruzi is associated with the induction of repetitive Ca2+ transients and subsequent invasion by the parasite of a number of mammalian cell lines, including tissue culture L6E2 myoblasts (B. A. Burleigh and N. W. Andrews, J. Biol. Chem. 270:5172-5180, 1995; S. N. J. Moreno, J. Silva, A. E. Vercesi, and R. Docampo, J. Exp. Med. 180:1535-1540, 1994; A. Rodríguez, M. G. Rioult, A. Ora, and N. W. Andrews, J. Cell Biol. 129:1263-1273, 1995; I. Tardieux, M. H. Nathanson, and N. W. Andrews, J. Exp. Med. 179:1017-1022, 1994). Using single cell spectrofluorometry and whole-cell patch clamping, we show that TSF produces rapid repetitive cytosolic Ca2+ transients (each associated with cell contraction) in primary cardiac myocytes isolated from dogs. The response of myocytes to TSF was dose dependent in that increasing numbers of cells responded to increasing concentrations of TSF. The TSF-induced Ca2+ transients could be obliterated when TSF was heated or treated with trypsin or the protease inhibitor leupeptin. Aprotinin, pepstatin A, and E-64 did not affect TSF activity. The TSF-induced Ca2+ transients and trypomastigote cell invasion could not be inhibited by alpha (prazosin)- or beta (propanolol)-adrenergic blockers or L-type Ca2+ channel blockers (verapamil, nisoldipine, or cadmium) or by removal of extracellular Ca2+. However, inhibition of pertussis toxin-sensitive G proteins and Ca2+ release from the sarcoplasmic reticulum (with thapsigargin or ryanodine) prevented the TSF-induced Ca2+ transients and cell invasion by trypomastigotes. These data suggested that cardiac myocyte pertussis toxin-sensitive G proteins are associated with the regulation of TSF-induced Ca2+ transients and myocyte invasion by trypomastigotes but are independent of Ca2+ entry into the cytosol via L-type Ca2+ channels. The Ca2+ transients are dependent on release of Ca2+ from sarcoplasmic

  10. Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients

    NASA Technical Reports Server (NTRS)

    Belcastro, C. M.

    1984-01-01

    Advanced composite aircraft designs include fault-tolerant computer-based digital control systems with thigh reliability requirements for adverse as well as optimum operating environments. Since aircraft penetrate intense electromagnetic fields during thunderstorms, onboard computer systems maya be subjected to field-induced transient voltages and currents resulting in functional error modes which are collectively referred to as digital system upset. A methodology was developed for assessing the upset susceptibility of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general-purpose microprocessor were studied via tests which involved the random input of analog transients which model lightning-induced signals onto interface lines of an 8080-based microcomputer from which upset error data were recorded. The application of Markov modeling to upset susceptibility estimation is discussed and a stochastic model development.

  11. Gold nanoparticles quench fluorescence by phase induced radiative rate suppression.

    PubMed

    Dulkeith, E; Ringler, M; Klar, T A; Feldmann, J; Muñoz Javier, A; Parak, W J

    2005-04-01

    The fluorescence quantum yield of Cy5 molecules attached to gold nanoparticles via ssDNA spacers is measured for Cy5-nanoparticle distances between 2 and 16 nm. Different numbers of ssDNA per nanoparticle allow to fine-tune the distance. The change of the radiative and nonradiative molecular decay rates with distance is determined using time-resolved photoluminescence spectroscopy. Remarkably, the distance dependent quantum efficiency is almost exclusively governed by the radiative rate.

  12. Synergistic Effect of Bolus Exposure to Zinc Oxide Nanoparticles on Bleomycin-Induced Secretion of Pro-Fibrotic Cytokines without Lasting Fibrotic Changes in Murine Lungs

    PubMed Central

    Wu, Wenting; Ichihara, Gaku; Hashimoto, Naozumi; Hasegawa, Yoshinori; Hayashi, Yasuhiko; Tada-Oikawa, Saeko; Suzuki, Yuka; Chang, Jie; Kato, Masashi; D’Alessandro-Gabazza, Corina N.; Gabazza, Esteban C.; Ichihara, Sahoko

    2014-01-01

    Zinc oxide (ZnO) nanoparticles are widely used in various products, and the safety evaluation of this manufactured material is important. The present study investigated the inflammatory and fibrotic effects of pulmonary exposure to ZnO nanoparticles in a mouse model of pulmonary fibrosis. Pulmonary fibrosis was induced by constant subcutaneous infusion of bleomycin (BLM). Female C57BL/6Jcl mice were divided into BLM-treated and non-treated groups. In each treatment group, 0, 10, 20 or 30 µg of ZnO nanoparticles were delivered into the lungs through pharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and the lungs were sampled at Day 10 or 14 after administration. Pulmonary exposure by a single bolus of ZnO nanoparticles resulted in severe, but transient inflammatory infiltration and thickening of the alveolar septa in the lungs, along with the increase of total and differential cell counts in BLAF. The BALF level of interleukin (IL)-1β and transforming growth factor (TGF)-β was increased at Day 10 and 14, respectively. At Day 10, the synergistic effect of BLM and ZnO exposure was detected on IL-1β and monocyte chemotactic protein (MCP)-1 in BALF. The present study demonstrated the synergistic effect of pulmonary exposure to ZnO nanoparticles and subcutaneous infusion of BLM on the secretion of pro-fibrotic cytokines in the lungs. PMID:25561223

  13. Hepcidin-Induced Iron Deficiency Is Related to Transient Anemia and Hypoferremia in Kawasaki Disease Patients

    PubMed Central

    Huang, Ying-Hsien; Kuo, Ho-Chang; Huang, Fu-Chen; Yu, Hong-Ren; Hsieh, Kai-Sheng; Yang, Ya-Ling; Sheen, Jiunn-Ming; Li, Sung-Chou; Kuo, Hsing-Chun

    2016-01-01

    Kawasaki disease (KD) is a type of systemic vasculitis that primarily affects children under the age of five years old. For sufferers of KD, intravenous immunoglobulin (IVIG) has been found to successfully diminish the occurrence of coronary artery lesions. Anemia is commonly found in KD patients, and we have shown that in appropriately elevated hepcidin levels are related to decreased hemoglobin levels in these patients. In this study, we investigated the time period of anemia and iron metabolism during different stages of KD. A total of 100 patients with KD and 20 control subjects were enrolled in this study for red blood cell and hemoglobin analysis. Furthermore, plasma, urine hepcidin, and plasma IL-6 levels were evaluated using enzyme-linked immunosorbent assay in 20 KD patients and controls. Changes in hemoglobin, plasma iron levels, and total iron binding capacity (TIBC) were also measured in patients with KD. Hemoglobin, iron levels, and TIBC were lower (p < 0.001, p = 0.009, and p < 0.001, respectively) while plasma IL-6 and hepcidin levels (both p < 0.001) were higher in patients with KD than in the controls prior to IVIG administration. Moreover, plasma hepcidin levels were positively and significantly correlated with urine hepcidin levels (p < 0.001) prior to IVIG administration. After IVIG treatment, plasma hepcidin and hemoglobin levels significantly decreased (both p < 0.001). Of particular note was a subsequent gradual increase in hemoglobin levels during the three weeks after IVIG treatment; nevertheless, the hemoglobin levels stayed lower in KD patients than in the controls (p = 0.045). These findings provide a longitudinal study of hemoglobin changes and among the first evidence that hepcidin induces transient anemia and hypoferremia during KD’s acute inflammatory phase. PMID:27187366

  14. Epimural Indicator Phylotypes of Transiently-Induced Subacute Ruminal Acidosis in Dairy Cattle

    PubMed Central

    Wetzels, Stefanie U.; Mann, Evelyne; Metzler-Zebeli, Barbara U.; Pourazad, Poulad; Qumar, Muhammad; Klevenhusen, Fenja; Pinior, Beate; Wagner, Martin; Zebeli, Qendrim; Schmitz-Esser, Stephan

    2016-01-01

    The impact of a long-term subacute rumen acidosis (SARA) on the bovine epimural bacterial microbiome (BEBM) and its consequences for rumen health is poorly understood. This study aimed to investigate shifts in the BEBM during a long-term transient SARA model consisting of two concentrate-diet-induced SARA challenges separated by a 1-week challenge break. Eight cows were fed forage and varying concentrate amounts throughout the experiment. In total, 32 rumen papilla biopsies were taken for DNA isolation (4 sampling time points per cow: at the baseline before concentrate was fed, after the first SARA challenge, after the challenge break, and after the second SARA challenge). Ruminal pH was continuously monitored. The microbiome was determined using Illumina MiSeq sequencing of the 16S rRNA gene (V345 region). In total 1,215,618 sequences were obtained and clustered into 6833 operational taxonomic units (OTUs). Campylobacter and Kingella were the most abundant OTUs (16.5 and 7.1%). According to ruminal pH dynamics, the second challenge was more severe than the first challenge. Species diversity estimates and evenness increased during the challenge break compared to all other sampling time points (P < 0.05). During both SARA challenges, Kingella- and Azoarcus-OTUs decreased (0.5 and 0.4 fold-change) and a dominant Ruminobacter-OTU increased during the challenge break (18.9 fold-change; P < 0.05). qPCR confirmed SARA-related shifts. During the challenge break noticeably more OTUs increased compared to other sampling time points. Our results show that the BEBM re-establishes the baseline conditions slower after a SARA challenge than ruminal pH. Key phylotypes that were reduced during both challenges may help to establish a bacterial fingerprint to facilitate understanding effects of SARA conditions on the BEBM and their consequences for the ruminant host. PMID:26973642

  15. Hepcidin-Induced Iron Deficiency Is Related to Transient Anemia and Hypoferremia in Kawasaki Disease Patients.

    PubMed

    Huang, Ying-Hsien; Kuo, Ho-Chang; Huang, Fu-Chen; Yu, Hong-Ren; Hsieh, Kai-Sheng; Yang, Ya-Ling; Sheen, Jiunn-Ming; Li, Sung-Chou; Kuo, Hsing-Chun

    2016-05-12

    Kawasaki disease (KD) is a type of systemic vasculitis that primarily affects children under the age of five years old. For sufferers of KD, intravenous immunoglobulin (IVIG) has been found to successfully diminish the occurrence of coronary artery lesions. Anemia is commonly found in KD patients, and we have shown that in appropriately elevated hepcidin levels are related to decreased hemoglobin levels in these patients. In this study, we investigated the time period of anemia and iron metabolism during different stages of KD. A total of 100 patients with KD and 20 control subjects were enrolled in this study for red blood cell and hemoglobin analysis. Furthermore, plasma, urine hepcidin, and plasma IL-6 levels were evaluated using enzyme-linked immunosorbent assay in 20 KD patients and controls. Changes in hemoglobin, plasma iron levels, and total iron binding capacity (TIBC) were also measured in patients with KD. Hemoglobin, iron levels, and TIBC were lower (p < 0.001, p = 0.009, and p < 0.001, respectively) while plasma IL-6 and hepcidin levels (both p < 0.001) were higher in patients with KD than in the controls prior to IVIG administration. Moreover, plasma hepcidin levels were positively and significantly correlated with urine hepcidin levels (p < 0.001) prior to IVIG administration. After IVIG treatment, plasma hepcidin and hemoglobin levels significantly decreased (both p < 0.001). Of particular note was a subsequent gradual increase in hemoglobin levels during the three weeks after IVIG treatment; nevertheless, the hemoglobin levels stayed lower in KD patients than in the controls (p = 0.045). These findings provide a longitudinal study of hemoglobin changes and among the first evidence that hepcidin induces transient anemia and hypoferremia during KD's acute inflammatory phase.

  16. Optical forces on metallic nanoparticles induced by a photonic nanojet.

    PubMed

    Cui, Xudong; Erni, Daniel; Hafner, Christian

    2008-09-01

    We investigate the optical forces acting on a metallic nanoparticle when the nanoparticle is introduced within a photonic nanojet (PNJ). Optical forces at resonance and off-resonance conditions of the microcylinder or nanoparticle are investigated. Under proper polarization conditions, the whispering gallery mode can be excited in the microcylinder, even at off resonance provided that scattering from the nanoparticle is strong enough. The optical forces are enhanced at resonance either of the single microcylinder or of the nanoparticle with respect to the forces under off-resonant illuminations. We found that the optical forces acting on the nanoparticle depend strongly on the dielectric permittivity of the nanoparticle, as well as on the intensity and the beam width of the PNJ. Hence, metallic sub-wavelength nanoparticle can be efficiently trapped by PNJs. Furthermore, the PNJ's attractive force can be simply changed to a repulsive force by varying the polarization of the incident beam. The changed sign of the force is related to the particle's polarizability and the excitation of localized surface plasmons in the nanoparticle.

  17. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    SciTech Connect

    Zevenhoven, Koos C. J. Ilmoniemi, Risto J.; Dong, Hui; Clarke, John

    2015-01-19

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents.

  18. Hyperperfusion counteracted by transient rapid vasoconstriction followed by long-lasting oligemia induced by cortical spreading depression in anesthetized mice

    PubMed Central

    Unekawa, Miyuki; Tomita, Yutaka; Toriumi, Haruki; Osada, Takashi; Masamoto, Kazuto; Kawaguchi, Hiroshi; Itoh, Yoshiaki; Kanno, Iwao; Suzuki, Norihiro

    2015-01-01

    Cortical spreading depression (CSD) involves mass depolarization of neurons and glial cells accompanied with changes in regional cerebral blood flow (rCBF) and energy metabolism. To further understand the mechanisms of CBF response, we examined the temporal diametric changes in pial arteries, pial veins, and cortical capillaries. In urethane-anesthetized mice, the diameters of these vessels were measured while simultaneously recording rCBF with a laser Doppler flowmeter. We observed a considerable increase in rCBF during depolarization in CSD induced by application of KCl, accompanied by a transient dip of rCBF with marked vasoconstriction of pial arteries, which resembled the response to pin-prick-induced CSD. Arterial constriction diminished or disappeared during the second and third passages of CSD, whereas the rCBF increase was maintained without a transient dip. Long-lasting oligemia with a decrease in the reciprocal of mean transit time of injected dye and mild constriction of pial arteries was observed after several passages of the CSD wave. These results indicate that CSD-induced rCBF changes consist of initial hyperemia with a transient dip and followed by a long-lasting oligemia, partially corresponding to the diametric changes of pial arteries, and further suggest that vessels other than pial arteries, such as intracortical vessels, are involved. PMID:25586145

  19. Gold nanoparticle plasmonics enhanced ultrafast laser-induced optoporation and stimulation of targeted cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Meunier, Michel; Bergeron, Éric; Lavoie-Cardinal, Flavie; Boutopoulos, Christos; Salesse, Charleen; Winnik, Françoise M.; De Koninck, Paul

    2016-03-01

    Gold nanoparticles (AuNPs) have found numerous applications in nanomedicine in view of their robustness, ease of functionalization and low toxicity. Upon irradiation of AuNPs by a pulsed ultrafast laser, various highly localized phenomena can be obtained including a temperature rise, pressure wave, charge injection and production of nanobubbles close to the cellular membrane [1]. These phenomena can be used to manipulate, optoperforate, transfect and stimulate targeted cells [2-5]. Irradiating at 800 nm in the optically biological transparent window, we demonstrated local optoporation and transfection of cells as well as local stimulation of neurons. Two recent examples will be given: (i) Laser-induced selective optoporation of cells: The technique can be used on various types of cells and a proof of principle will be given on human cancer cells in a co-culture using functionalized AuNPs [6]. (ii) Laser-induced stimulation of neurons and monitoring of the localized Ca2+ signaling: This all optical method uses a standard confocal microscope to trigger a transient increase in free Ca2+ in neurons covered by functionalized AuNPs as well as to measure these local variations optically with the Ca2+ sensor GCaMP6s [7]. The proposed techniques provide a new complement to light-dependent methods in neuroscience. REFERENCES (by our group): (1) Boulais, J. Photochem. Photobiol. C Photochem. Rev. 17, 26 (2013); (2) Baumgart, Biomaterials 33, 2345 (2012); (3) Boulais, NanoLett. 12, 4763 (2012); (4) Boutopoulos, J. Biophotonics (2015); (5) Boutopoulos, Nanoscale 7, 11758 (2015); (6) Bergeron, Biomaterials, submitted (2015); (7) Lavoie-Cardinal, Nature Commun. submitted (2015).

  20. Formation of silicon nanoparticles by a pressure induced nucleation mechanism

    NASA Astrophysics Data System (ADS)

    Kang, Myung-Koo; Kim, Si Joon; Kim, Hyun Jae

    2013-03-01

    Formation of silicon nanoparticles (SiNPs) was achieved using excimer laser crystallization of an amorphous Si (a-Si) thin film using a SiO2 capping layer (C/L) with improved thin-film transistor (TFT) performance due to the enlarged grain size of polycrystalline Si (poly-Si). After laser irradiation of an a-Si thin film covered with C/L, fluctuation in the surface morphology of the C/L was observed above the critical laser energy density (Ecr) with the formation of SiNPs. The grain size of the poly-Si layer after crystallization increased abruptly at the same time. A non-uniform pressure distribution beneath the SiO2 C/L was proposed for the initiation of nucleation, which is named pressure induced nucleation (PIN) mechanism. Following nucleation, the release of latent heat made it difficult for the remnant liquid Si to solidify and the volume increased due to the density difference between the liquid and solid Si. Consequently, the pressure on the liquid Si caused SiNPs to sprout through the SiO2 C/L as grains grew from the low temperature to high temperature point. This study offers not only a simple method to fabricate SiNPs with controllable size/density but also larger grain size with lower laser energy density, which leads to higher TFT performance.

  1. Redox Nanoparticle Therapeutics for Acetaminophen-Induced Hepatotoxicity in Mice

    PubMed Central

    Boonruamkaew, Phetcharat; Chonpathompikunlert, Pennapa; Nagasaki, Yukio

    2016-01-01

    The purpose of this study was to evaluate the hepatoprotective effect of an antioxidative nanoparticle (RNPN) recently developed against APAP-induced hepatotoxicity in mice. The effects of oral administration of RNPN to APAP-treated mice were assessed for various biochemical liver function parameters: alanine transaminase (ALT) activity, aspartate transaminase (AST) activity, alkaline phosphatase (ALP) activity, prothrombin time, and serum albumin (ALB) level. The treatment effects were assessed in terms of free radical parameters: malondialdehyde (MDA) accumulation, glutathione peroxidase (GPx) activity, % inhibition of superoxide anion (O2−∙), and histopathological examination. The N-acetylcysteine (NAC)-treated group exhibited an enhanced prothrombin time relative to the control group, while RNPN did not prolong prothrombin time. The RNPN-treated animals exhibited lower levels of ALT, AST, and ALP, while increased ALB levels were measured in these animals compared to those in the other groups. The RNPN-treated animals furthermore exhibited improved MDA levels, GPx activity, and % inhibition of O2−∙, which relate to oxidative damage. Histological staining of liver tissues from RNPN-treated animals did not reveal any microscopic changes relative to the other groups. The findings of this study suggest that RNPN possesses effective hepatoprotective properties and does not exhibit the notable adverse effects associated with NAC treatment. PMID:27073589

  2. Fullerenol nanoparticles prevents doxorubicin-induced acute hepatotoxicity in rats.

    PubMed

    Jacevic, Vesna; Djordjevic, Aleksandar; Srdjenovic, Branislava; Milic-Tores, Vukosava; Segrt, Zoran; Dragojevic-Simic, Viktorija; Kuca, Kamil

    2017-03-16

    Doxorubicin (DOX), commonly used antineoplastic agent, affects bone marrow, intestinal tract and heart, but it also has some hepatotoxic effects. Main mechanism of its toxicity is the production of free reactive oxygen species. Polyhidroxilated C60 fullerene derivatives, fullerenol nanoparticles (FNP), act as free radical scavengers in in vitro systems. The aim of the study was to investigate potential FNP protective role against DOX-induced hepatotoxicity in rats. Experiments were performed on adult male Wistar rats. Animals were divided into five groups: (1) 0.9% NaCl (control), (2) 100mg/kg ip FNP, (3) 10mg/kg DOX iv, (4) 50mg/kg ip FNP 30min before 10mg/kg iv DOX, (5) 100mg/kg ip FNP 30min before 10mg/kg iv DOX. A general health condition, body and liver weight, TBARS level and antioxidative enzyme activity, as well as pathohistological examination of the liver tissue were conducted on days 2 and 14 of the study. FNP, applied alone, did not alter any examinated parameters. However, when used as a pretreatment it significantly increased survival rate, body and liver weight, and decreased TBARS level, antioxidative enzyme activity and hepatic damage score in DOX-treated rats. FNP administered at a dose of 100mg/kg significantly attenuated effects of doxorubicin administered in a single high dose in rats, concerning general condition, body and liver weight, lipid peroxidation level and antioxidative enzyme activity as well as structural alterations of the hepatic tissue.

  3. Engineered nanoparticles induce cell apoptosis: potential for cancer therapy

    PubMed Central

    Ma, Dan-Dan; Yang, Wan-Xi

    2016-01-01

    Engineered nanoparticles (ENPs) have been widely applied in industry, commodities, biology and medicine recently. The potential for many related threats to human health has been highlighted. ENPs with their sizes no larger than 100 nm are able to enter the human body and accumulate in organs such as brain, liver, lung, testes, etc, and cause toxic effects. Many references have studied ENP effects on the cells of different organs with related cell apoptosis noted. Understanding such pathways towards ENP induced apoptosis may aid in the design of effective cancer targeting ENP drugs. Such ENPs can either have a direct effect towards cancer cell apoptosis or can be used as drug delivery agents. Characteristics of ENPs, such as sizes, shape, forms, charges and surface modifications are all seen to play a role in determining their toxicity in target cells. Specific modifications of such characteristics can be applied to reduce ENP bioactivity and thus alleviate unwanted cytotoxicity, without affecting the intended function. This provides an opportunity to design ENPs with minimum toxicity to non-targeted cells. PMID:27056889

  4. Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles

    PubMed Central

    Romero-Urbina, Dulce G; Lara, Humberto H; Velázquez-Salazar, J Jesús; Arellano-Jiménez, M Josefina; Larios, Eduardo; Srinivasan, Anand; Lopez-Ribot, Jose L

    2015-01-01

    Summary Silver nanoparticles offer a possible means of fighting antibacterial resistance. Most of their antibacterial properties are attributed to their silver ions. In the present work, we study the actions of positively charged silver nanoparticles against both methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. We use aberration-corrected transmission electron microscopy to examine the bactericidal effects of silver nanoparticles and the ultrastructural changes in bacteria that are induced by silver nanoparticles. The study revealed that our 1 nm average size silver nanoparticles induced thinning and permeabilization of the cell wall, destabilization of the peptidoglycan layer, and subsequent leakage of intracellular content, causing bacterial cell lysis. We hypothesize that positively charged silver nanoparticles bind to the negatively charged polyanionic backbones of teichoic acids and the related cell wall glycopolymers of bacteria as a first target, consequently stressing the structure and permeability of the cell wall. This hypothesis provides a major mechanism to explain the antibacterial effects of silver nanoparticles on Staphylococcus aureus. Future research should focus on defining the related molecular mechanisms and their importance to the antimicrobial activity of silver nanoparticles. PMID:26734530

  5. Mitophagy induced by nanoparticle-peptide conjugates enabling an alternative intracellular trafficking route.

    PubMed

    Zhang, Zhaolei; Zhou, Lei; Zhou, Yanqing; Liu, Jinyin; Xing, Xiaoyun; Zhong, Jun; Xu, Guoqiang; Kang, Zhenhui; Liu, Jian

    2015-10-01

    The intracellular behaviors of nanoparticles are fundamentally important for the evaluation of their biosafety and the designs of nano carrier-assisted drug delivery with high therapeutic efficacy. It is still in a great need to discover how functionalized nanoparticles are transported inside the cells, for instance, in a complicated fashion of translocation between different types of cell organelles. Here we report a new understanding of the interactions between nanoparticles and cells by the development of polyoxometalates nanoparticle-peptide conjugates and investigation of their intracellular trafficking behaviors. The as-prepared nanoparticles are featured with a unique combination of fluorescence and high contrast for synchrotron X-ray-based imaging. Functional surface modification with peptides facilitates effective delivery of the nanoparticles onto the target organelle (mitochondria) and subsequent intracellular trafficking in a dynamic mode. Interestingly, our experimental results have revealed that autophagy of mitochondria (mitophagy) can be induced by NP-peptide as a cellular response for recycling the damaged organelles, through molecular mediation associated with the change of mitochondrial membrane potential. The biological effects induced by NP-peptide reciprocally affect the distribution patterns and fates of nanoparticles in the cell metabolism by providing an alternative route of intracellular trafficking. The new understanding of the mutual activities between nanoparticles and cells will enrich our approaches in the development of nanobiotechnology and nano-medicine for disease treatments.

  6. Multipolar optically induced electric and magnetic resonances in the ellipsoidal nanoparticles

    NASA Astrophysics Data System (ADS)

    Reena; Devi, Inder; Kalra, Yogita; Sinha, R. K.

    2016-09-01

    In this paper, electric and magnetic resonances induced in the ellipsoidal dielectric nanoparticles in the optical range have been analyzed. Circular displacement currents excited inside the elliptical nano-particles by the incident light result in magnetic dipolar resonance in the dielectric nanoparticles. Kerker's type scattering is observed due to the mutual interference of electric and magnetic resonances. The effect on the resonance conditions with the variation in the relative permittivity from Er= 5 to Er= 20 of the ellipsoidal nanoparticle has been observed. It has been analyzed that peaks of electric and magnetic resonances come closer by decreasing the electric permittivity of the nanoparticle, which leads to the increase in the directionality in the forward direction, as verified using Generalized Kerker's condition. Further, far field scattering patterns have been obtained using the finite element method. Here, the electric and magnetic resonances have been optically induced up to quadrupolar modes. There is enhancement of the directionality in the forward direction when electric and magnetic resonances are in phase. Further, the effect of size of the linear array of ellipsoidal nanoparticles on the directionality has been analyzed. It has been observed that there is increase in the directivity by increasing the chain of the nanoparticles. Thus, the ellipsoidal nanoparticles can lead to the design of low loss and highly directional optical nanoantennas.

  7. Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles.

    PubMed

    Romero-Urbina, Dulce G; Lara, Humberto H; Velázquez-Salazar, J Jesús; Arellano-Jiménez, M Josefina; Larios, Eduardo; Srinivasan, Anand; Lopez-Ribot, Jose L; Yacamán, Miguel José

    2015-01-01

    Silver nanoparticles offer a possible means of fighting antibacterial resistance. Most of their antibacterial properties are attributed to their silver ions. In the present work, we study the actions of positively charged silver nanoparticles against both methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. We use aberration-corrected transmission electron microscopy to examine the bactericidal effects of silver nanoparticles and the ultrastructural changes in bacteria that are induced by silver nanoparticles. The study revealed that our 1 nm average size silver nanoparticles induced thinning and permeabilization of the cell wall, destabilization of the peptidoglycan layer, and subsequent leakage of intracellular content, causing bacterial cell lysis. We hypothesize that positively charged silver nanoparticles bind to the negatively charged polyanionic backbones of teichoic acids and the related cell wall glycopolymers of bacteria as a first target, consequently stressing the structure and permeability of the cell wall. This hypothesis provides a major mechanism to explain the antibacterial effects of silver nanoparticles on Staphylococcus aureus. Future research should focus on defining the related molecular mechanisms and their importance to the antimicrobial activity of silver nanoparticles.

  8. Oxidative stress mediated apoptosis induced by nickel ferrite nanoparticles in cultured A549 cells.

    PubMed

    Ahamed, Maqusood; Akhtar, Mohd Javed; Siddiqui, Maqsood A; Ahmad, Javed; Musarrat, Javed; Al-Khedhairy, Abdulaziz A; AlSalhi, Mohamad S; Alrokayan, Salman A

    2011-05-10

    Due to the interesting magnetic and electrical properties with good chemical and thermal stabilities, nickel ferrite nanoparticles are being utilized in many applications including magnetic resonance imaging, drug delivery and hyperthermia. Recent studies have shown that nickel ferrite nanoparticles produce cytotoxicity in mammalian cells. However, there is very limited information concerning the toxicity of nickel ferrite nanoparticles at the cellular and molecular level. The aim of this study was to investigate the cytotoxicity, oxidative stress and apoptosis induction by well-characterized nickel ferrite nanoparticles (size 26 nm) in human lung epithelial (A549) cells. Nickel ferrite nanoparticles induced dose-dependent cytotoxicity in A549 cells demonstrated by MTT, NRU and LDH assays. Nickel ferrite nanoparticles were also found to induce oxidative stress evidenced by generation of reactive oxygen species (ROS) and depletion of antioxidant glutathione (GSH). Further, co-treatment with the antioxidant L-ascorbic acid mitigated the ROS generation and GSH depletion due to nickel ferrite nanoparticles suggesting the potential mechanism of oxidative stress. Quantitative real-time PCR analysis demonstrated that following the exposure of A549 cells to nickel ferrite nanoparticles, the level of mRNA expressions of cell cycle checkpoint protein p53 and apoptotic proteins (bax, caspase-3 and caspase-9) were significantly up-regulated, whereas the expression of anti-apoptotic proteins (survivin and bcl-2) were down-regulated. Moreover, activities of caspase-3 and caspase-9 enzymes were also significantly higher in nickel ferrite nanoparticles exposed cells. To the best of our knowledge this is the first report showing that nickel ferrite nanoparticles induced apoptosis in A549 cells through ROS generation and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways.

  9. Measurement of pump-induced transient lensing in a cryogenically-cooled high average power Ti:sapphire amplifier.

    PubMed

    Planchon, Thomas A; Amir, Wafa; Childress, Colby; Squier, Jeff A; Durfee, Charles G

    2008-11-10

    The transient thermal lensing in a liquid-nitrogren cooled kilohertz multipass amplifier is quantitatively measured with spatially-resolved Fourier transform spectral interferometry. A pump-probe arrangement allows the observation of a polarization-dependent non-thermal component following the fluorescence timescale: additional cooling would not suppress this residual lensing. We also observe a time-dependent thermal component that has a timescale sufficiently fast to indicate that there is cooling between shots even at a repetition rate of 1 kHz. The value of pump-induced lensing would be underestimated when performing time-averaged measurements of pump-induced phase shifts.

  10. Coalescence-induced crystallisation wave in Pd nanoparticles

    PubMed Central

    Grammatikopoulos, Panagiotis; Cassidy, Cathal; Singh, Vidyadhar; Sowwan, Mukhles

    2014-01-01

    Palladium nanoparticles offer an attractive alternative to bulk palladium for catalysis, hydrogen storage and gas sensing applications. Their performance depends strongly on surface structure; therefore, nanoparticle coalescence can play an important role, as it determines the resultant structure of the active sites where reactions (e.g. catalysis) actually take place, i.e. facets, edges, vertices or protrusions. With this in mind, we performed classical molecular dynamics (MD) simulations and magnetron-sputtering inert gas condensation depositions of palladium nanoparticles, supported by high-resolution transmission electron microscopy (HRTEM), to study the mechanisms that govern their coalescence. Surface energy minimisation drove the interactions initially, leading to the formation of an interface/neck, as expected. Intriguingly, at a later stage, atomic rearrangements triggered a crystallisation wave propagating through the amorphous nanoparticles, leading to mono- or polycrystalline fcc structures. In the case of crystalline nanoparticles, almost-epitaxial alignment occurred and the formation of twins and surface protrusions were observed. PMID:25047807

  11. Tumor Presence Induces Global Immune Changes and Enhances Nanoparticle Clearance.

    PubMed

    Kai, Marc P; Brighton, Hailey E; Fromen, Catherine A; Shen, Tammy W; Luft, J Christopher; Luft, Yancey E; Keeler, Amanda W; Robbins, Gregory R; Ting, Jenny P Y; Zamboni, William C; Bear, James E; DeSimone, Joseph M

    2016-01-26

    Long-circulating nanoparticles are essential for increasing tumor accumulation to provide therapeutic efficacy. While it is known that tumor presence can alter the immune system, very few studies have explored this impact on nanoparticle circulation. In this report, we demonstrate how the presence of a tumor can change the local and global immune system, which dramatically increases particle clearance. We found that tumor presence significantly increased clearance of PRINT hydrogel nanoparticles from the circulation, resulting in increased accumulation in the liver and spleen, due to an increase in M2-like macrophages. Our findings highlight the need to better understand interactions between immune status and nanoparticle clearance, and suggest that further consideration of immune function is required for success in preclinical and clinical nanoparticle studies.

  12. Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

    SciTech Connect

    Bocharova, Vera; Sharp, Danna; Jones, Aaron; Cheng, Shiwang; Griffin, Philip J.; Agapov, Alexander L.; Voylov, Dmitry; Wang, Yangyang; Kisliuk, Alexander; Melman, Artem; Sokolov, Alexei P.

    2015-03-09

    Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radii in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.

  13. Variation in photon-induced interface defects due to transient behavior of pulse modulated inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Miyoshi, Y.; Fukasawa, M.; Nagahata, K.; Tatsumi, T.; Liu, Z.; Zhang, Y.; Ando, A.; Takeda, K.; Ishikawa, K.; Sekine, M.; Hori, M.

    2016-09-01

    It is important to reduce photon-induced interface defects generated in the plasma process for electronic device performance. In this study, we investigated the effect of transient behavior of a pulse-modulated ICP on these defects. The C-V analysis revealed the pulse frequency (0.5 - 20 KHz) dependence of the interface state density (Dit) in the SiN/Si interface whose variation was proportional to the UV fluence from discharge. By increasing the frequency, the Dit increased, was a maximum at 10 kHz, and then decreased. The Dit was lower than that in the CW at the lower frequencies, but was higher at the higher frequencies (>10 KHz). The transient behavior of the pulse plasma is presumed to be the cause of this property. The time resolved OES revealed that the optical emission overshoot appeared after ignition due to the variation in the electron temperature and number density in the early ON phase. The number of overshoots increased with increasing frequency. Therefore, the UV fluence and the Dit were increased. At the higher frequencies, the variation in the electron temperature and number density were suppressed due to the stepwise ionization via long-lived metastable species. Therefore the overshoot amplitude decreased. As a result, the UV fluence and the Dit were decreased. The results revealed that control of the transient behavior of pulse-modulated plasma is important to reduce photon-induced defects in the plasma process.

  14. Mechanism of gold nanoparticles-induced trypsin inhibition: a multi-technique approach.

    PubMed

    Zhang, Hongmei; Cao, Jian; Wu, Shengde; Wang, Yanqing

    2014-08-01

    The binding interactions of gold nanoparticles with trypsin were investigated using multi-spectra methods and molecular modeling. The experiment data showed that trypsin modified the surface of gold nanoparticles. The fluorescence intensity of trypsin was quenched by gold nanoparticles that strongly associated with protein and induced the inhibition of enzyme activity. The electrostatic and hydrophobic interactions were the primary contributors to the binding forces between trypsin and gold nanoparticles. The covalent interactions might be also involved in the binding process. The modeling calculated results indicated that the binding site was near to the primary substrate-binding pocket and the active site of the enzyme substrate. This work elucidated the interaction mechanism of trypsin with gold nanoparticles from the theoretical and experimental angle.

  15. Spectrum of laser light scattered by nanoparticles in an ablation-induced cavitation bubble

    NASA Astrophysics Data System (ADS)

    Takeuchi, Masato; Sasaki, Koichi

    2016-04-01

    The spectrum of the laser light scattered by nanoparticles in a cavitation bubble, which was induced by laser ablation of a titanium target in water, was measured using a triple-grating spectrograph. The scattered laser light observed at 100 \\upmu s after laser ablation had no wavelength-shifted component, suggesting that nanoparticles at this delay time were metallic. The wavelength-shifted component was observed in the spectrum at a delay time of 200 \\upmu s, suggesting the formation of oxidized nanoparticles. However, we observed no peaks in the spectrum of the scattered laser light in the present in situ laser-light scattering experiment. On the other hand, we observed clear peaks in the Raman spectrum of synthesized nanoparticles. The experimental results suggest slow crystallization of nanoparticles in liquid in liquid-phase laser ablation.

  16. A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

    PubMed Central

    2013-01-01

    This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose. PMID:24225302

  17. Magnetically Induced Continuous CO2 Hydrogenation Using Composite Iron Carbide Nanoparticles of Exceptionally High Heating Power.

    PubMed

    Bordet, Alexis; Lacroix, Lise-Marie; Fazzini, Pier-Francesco; Carrey, Julian; Soulantica, Katerina; Chaudret, Bruno

    2016-12-19

    The use of magnetic nanoparticles to convert electromagnetic energy into heat is known to be a key strategy for numerous biomedical applications but is also an approach of growing interest in the field of catalysis. The heating efficiency of magnetic nanoparticles is limited by the poor magnetic properties of most of them. Here we show that the new generation of iron carbide nanoparticles of controlled size and with over 80 % crystalline Fe2.2 C leads to exceptional heating properties, which are much better than the heating properties of currently available nanoparticles. Associated to catalytic metals (Ni, Ru), iron carbide nanoparticles submitted to magnetic excitation very efficiently catalyze CO2 hydrogenation in a dedicated continuous-flow reactor. Hence, we demonstrate that the concept of magnetically induced heterogeneous catalysis can be successfully applied to methanation of CO2 and represents an approach of strategic interest in the context of intermittent energy storage and CO2 recovery.

  18. A case of drug-induced hypersensitivity syndrome showing transient immunosuppression before viral reactivation during treatment for pemphigus foliaceus.

    PubMed

    Takahashi, H; Tanaka, M; Tanikawa, A; Toyohara, A; Ogo, Y; Morimoto, A; Harato, R; Kobayashi, M; Amagai, M

    2006-01-01

    Drug-induced hypersensitivity syndrome (DIHS) is one of the most severe drug adverse reactions, with characteristic biphasic symptoms. Reactivation of human herpesvirus-6 (HHV-6) is frequently observed, although the cause of DIHS is still unknown. A patient developed DIHS during treatment with diaminodiphenylsulphone for pemphigus foliaceus. The number of lymphocytes in his peripheral blood, and titres of serum total IgG and IgM and anti-desmoglein1 antibody transiently decreased just before reactivation of HHV-6, cytomegalovirus and Epstein-Barr virus. This observation suggests that transient suppression of both cellular and humoral immunity may trigger viral reactivation, which leads to the development of the second phase of DIHS.

  19. Flow non-normality-induced transient growth in superposed Newtonian and non-Newtonian fluid layers.

    PubMed

    Camporeale, C; Gatti, F; Ridolfi, L

    2009-09-01

    In recent years non-normality and transient growths have attracted much interest in fluid mechanics. Here, we investigate these topics with reference to the problem of interfacial instability in superposed Newtonian and non-Newtonian fluid layers. Under the hypothesis of the lubrication theory, we demonstrate the existence of significant transient growths in the parameter space region where the dynamical system is asymptotically stable, and show how they depend on the main physical parameters. In particular, the key role of the density ratio is highlighted.

  20. Transient growth approach to estimation of roughness-induced nosetip transition

    NASA Astrophysics Data System (ADS)

    Reshotko, Eli; Tumin, Anatoli

    2001-11-01

    Boundary layer transition on sphere-cone nosetips in hypersonic flow is often observed to occur on the sphere, ahead of the sonic point, in a region that is highly stable to T-S disturbances. This transition is generally attributed to surface roughness even in cases where the surface is nominally smooth. A model is here developed based on transient growth theory for this transition. The model includes effects of surface curvature on the transient growth factors. The model is compared with the transition data-base and correlations of Batt & Legner and others.

  1. Different cell responses induced by exposure to maghemite nanoparticles

    NASA Astrophysics Data System (ADS)

    Luengo, Yurena; Nardecchia, Stefania; Morales, María Puerto; Serrano, M. Concepción

    2013-11-01

    Recent advances in nanotechnology have permitted the development of a wide repertoire of inorganic magnetic nanoparticles (NPs) with extensive promise for biomedical applications. Despite this remarkable potential, many questions still arise concerning the biocompatible nature of NPs when in contact with biological systems. Herein, we have investigated how controlled changes in the physicochemical properties of iron oxide NPs at their surface (i.e., surface charge and hydrodynamic size) affect, first, their interaction with cell media components and, subsequently, cell responses to NP exposure. For that purpose, we have prepared iron oxide NPs with three different coatings (i.e., dimercaptosuccinic acid - DMSA, (3-aminopropyl)triethoxysilane - APS and dextran) and explored the response of two different cell types, murine L929 fibroblasts and human Saos-2 osteoblasts, to their exposure. Interestingly, different cell responses were found depending on the NP concentration, surface charge and cell type. In this sense, neutral NPs, as those coated with dextran, induced negligible cell damage, as their cellular internalization was significantly reduced. In contrast, surface-charged NPs (i.e., those coated with DMSA and APS) caused significant cellular changes in viability, morphology and cell cycle under certain culture conditions, as a result of a more active cellular internalization. These results also revealed a particular cellular ability to detect and remember the original physicochemical properties of the NPs, despite the formation of a protein corona when incubated in culture media. Overall, conclusions from these studies are of crucial interest for future biomedical applications of iron oxide NPs.Recent advances in nanotechnology have permitted the development of a wide repertoire of inorganic magnetic nanoparticles (NPs) with extensive promise for biomedical applications. Despite this remarkable potential, many questions still arise concerning the biocompatible

  2. Joule heating induced transient temperature field and its effects on electroosmosis in a microcapillary packed with microspheres.

    PubMed

    Kang, Y; Yang, C; Huang, X

    2005-08-02

    The Joule heating induced transient temperature field and its effect on the electroosmotic flow in a capillary packed with microspheres is analyzed numerically using the control-volume-based finite difference method. The model incorporates the coupled momentum equation for the electroosmotic velocity, the energy equations for the Joule heating induced temperature distributions in both the packed column and the capillary wall, and the mass and electric current continuity equations. The temperature-dependent physical properties of the electrolyte solution are taken into consideration. The characteristics of the Joule heating induced transient development of temperature and electroosmotic flow fields are studied. Specifically, the simulation shows that the presence of Joule heating causes a noticeable axial temperature gradient in the thermal entrance region and elevates a significant temperature increment inside the microcapillary. The temperature changes in turn greatly affect the electroosmotic velocity by means of the temperature-dependent fluid viscosity, dielectric constant, and local electric field strength. Furthermore, the model predicts an induced pressure gradient to counterbalance the axial variation of the electroosmotic velocity so as to maintain the fluid mass continuity. In addition, under specific conditions, the present model is validated by comparing with the existing analytical model and experimental data from the literature.

  3. Inhibition of Kupffer Cell Autophagy Abrogates Nanoparticle-Induced Liver Injury.

    PubMed

    Zhu, Shasha; Zhang, Jiqian; Zhang, Li; Ma, Wentao; Man, Na; Liu, Yiming; Zhou, Wei; Lin, Jun; Wei, Pengfei; Jin, Peipei; Zhang, Yunjiao; Hu, Yi; Gu, Erwei; Lu, Xianfu; Yang, Zhilai; Liu, Xuesheng; Bai, Li; Wen, Longping

    2017-02-24

    The possible adverse effects of engineered nanomaterials on human health raise increasing concern as our research on nanosafety intensifies. Upon entry into a human body, whether intended for a theranostic purpose or through unintended exposure, nanomaterials tend to accumulate in the liver, leading to hepatic damage. A variety of nanoparticles, including rare earth upconversion nanoparticles (UCNs), have been reported to elicit hepatotoxicity, in most cases through inducing immune response or activating reactive oxygen species. Many of these nanoparticles also induce autophagy, and autophagy inhibition has been shown to decrease UCN-induced liver damage. Herein, using UCNs as a model engineered nanomaterial, this study uncovers a critical role for Kupffer cells in nanomaterial-induced liver toxicity, as depletion of Kupffer cells significantly exacerbates UCN-induced liver injury. Furthermore, UCN-induced prodeath autophagy in Kupffer cells, and inhibition of autophagy with 3-MA, a well-established chemical inhibitor of autophagy, enhances Kupffer cell survival and further abrogates UCN-induced liver toxicity. The results reveal the critical importance of Kupffer cell autophagy for nanoparticle-induced liver damage, and inhibition of autophagy may constitute a novel strategy for abrogating nanomaterial-elicited liver toxicity.

  4. Anti-Adhesive Behaviors between Solid Hydrate and Liquid Aqueous Phase Induced by Hydrophobic Silica Nanoparticles.

    PubMed

    Min, Juwon; Baek, Seungjun; Somasundaran, P; Lee, Jae W

    2016-09-20

    This study introduces an "anti-adhesive force" at the interface of solid hydrate and liquid solution phases. The force was induced by the presence of hydrophobic silica nanoparticles or one of the common anti-agglomerants (AAs), sorbitan monolaurate (Span 20), at the interface. The anti-adhesive force, which is defined as the maximum pushing force that does not induce the formation of a capillary bridge between the cyclopentane (CP) hydrate particle and the aqueous solution, was measured using a microbalance. Both hydrophobic silica nanoparticles and Span 20 can inhibit adhesion between the CP hydrate probe and the aqueous phase because silica nanoparticles have an aggregative property at the interface, and Span 20 enables the hydrate surface to be wetted with oil. Adding water-soluble sodium dodecyl sulfate (SDS) to the nanoparticle system cannot affect the aggregative property or the distribution of silica nanoparticles at the interface and, thus, cannot change the anti-adhesive effect. However, the combined system of Span 20 and SDS dramatically reduces the interfacial tension: emulsion drops were formed at the interface without any energy input and were adsorbed on the CP hydrate surface, which can cause the growth of hydrate particles. Silica nanoparticles have a good anti-adhesive performance with a relatively smaller dosage and are less influenced by the presence of molecular surfactants; consequently, these nanoparticles may have a good potential for hydrate inhibition as AAs.

  5. Silver nanoparticles induce apoptotic cell death in Candida albicans through the increase of hydroxyl radicals.

    PubMed

    Hwang, In-sok; Lee, Juneyoung; Hwang, Ji Hong; Kim, Keuk-Jun; Lee, Dong Gun

    2012-04-01

    Silver nanoparticles have been shown to be detrimental to fungal cells although the mechanism(s) of action have not been clearly established. In this study, we used Candida albicans cells to show that silver nanoparticles exert their antifungal effect through apoptosis. Many studies have shown that the accumulation of reactive oxygen species induces and regulates the induction of apoptosis. Furthermore, hydroxyl radicals are considered an important component of cell death. Therefore, we assumed that hydroxyl radicals were related to apoptosis and the effect of thiourea as a hydroxyl radical scavenger was investigated. We measured the production of reactive oxygen species and investigated whether silver nanoparticles induced the accumulation of hydroxyl radicals. A reduction in the mitochondrial membrane potential shown by flow cytometry analysis and the release of cytochrome c from mitochondria were also verified. In addition, the apoptotic effects of silver nanoparticles were detected by fluorescence microscopy using other confirmed diagnostic markers of yeast apoptosis including phosphatidylserine externalization, DNA and nuclear fragmentation, and the activation of metacaspases. Cells exposed to silver nanoparticles showed increased reactive oxygen species and hydroxyl radical production. All other phenomena of mitochondrial dysfunction and apoptotic features also appeared. The results indicate that silver nanoparticles possess antifungal effects with apoptotic features and we suggest that the hydroxyl radicals generated by silver nanoparticles have a significant role in mitochondrial dysfunctional apoptosis.

  6. High-resolution, parallel patterning of nanoparticles via an ion-induced focusing mask.

    PubMed

    You, Sukbeom; Han, Kyuhee; Kim, Hyoungchul; Lee, Heechul; Woo, Chang Gyu; Jeong, Changui; Nam, Woongsik; Choi, Mansoo

    2010-10-04

    An ion-induced focusing mask under the simultaneous injection of ions and charged aerosols generates invisible electrostatic lenses around each opening, through which charged nanoparticles are convergently guided without depositing on the mask surface. The sizes of the created features become significantly smaller than those of the mask openings due to the focusing capability. It is not only demonstrated that material-independent nanoparticles including proteins can be patterned as an ordered array on any surface regardless of the conductive, nonconductive, or flexible nature of the substrate, but also that the array density can be increased. Highly sensitive gas sensors based on these focused nanoparticle patterns are fabricated via the concept.

  7. Electric-Field-Induced Alignment of Block Copolymer/Nanoparticle Blends

    SciTech Connect

    Liedel, Clemens; Schindler, Kerstin; Pavan, Mariela J.; Lewin, Christian; Pester, Christian W; Ruppel, Markus A; Urban, Volker S; Shenhar, Roy; Boker, Alexander

    2013-01-01

    External electric fi elds readily align birefringent block-copolymer mesophases. In this study the effect of gold nanoparticles on the electric-fi eld-induced alignment of a lamellae-forming polystyrene- block -poly(2-vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric-fi eldassisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such fi lms under benign experimental conditions.

  8. Spectral Induced Polarization Measurements of Nanoparticles in Laboratory Column Experiments

    EPA Science Inventory

    Nano sized materials are prevalent in consumer goods, manufacturing, industrial processes, and remediation technologies. The intentional and accidental introduction of nanoparticles (NP) into the subsurface pose a potential risk to the environment and public health. This resea...

  9. Aqueous medium induced optical transitions in cerium oxide nanoparticles

    SciTech Connect

    Inerbaev, Talgat M.; Karakoti, Ajay S.; Kuchibhatla, S. V. N. T.; Kumar, Amit; Masunov, Artem E.; Seal, Sudipta

    2015-03-07

    Experimental and theoretical investigations were performed to investigate the effect of water on optical properties of nanoceria as a function of Ce3+ concentration. Theoretical studies based on density functional plane-wave calculations reveal that the indirect optical transitions in bare ceria nanoparticles are red-shifted with an increase in the concentration of Ce3+. However, ceria nanoparticles model with adsorbed water molecules show a blue shift in the indirect optical spectra under identical conditions. Direct optical transitions are almost independent of Ce3+ concentration but show a pronounced blue shift in the aqueous environment relative to the bare nanoparticles. The theoretical study is consistent with our experimental observation in difference of shift behaviour in bare and aqueous suspended ceria nanoparticles. This change from red- to blue-shift in indirect optical transitions is associated with the polarization effect of water molecules on f-electron states.

  10. Ionic liquid-induced synthesis of selenium nanoparticles

    SciTech Connect

    Langi, Bhushan; Shah, Chetan; Singh, Krishankant; Chaskar, Atul; Kumar, Manmohan; Bajaj, Parma N.

    2010-06-15

    A simple wet chemical method has been used to synthesize selenium nanoparticles by the reaction of ionic liquid with sodium selenosulphate, a selenium precursor, in the presence of polyvinyl alcohol stabilizer, in aqueous medium. The method is capable of producing spherical selenium nanoparticles in the size range of 76-150 nm under ambient conditions. This is a first report on the production of nano-selenium assisted by an ionic liquid. The synthesized nanoparticles can be separated easily from the aqueous sol by a high-speed centrifuge machine, and can be re-dispersed in an aqueous medium. The synthesized selenium nanoparticles have been characterized by X-ray diffraction, energy dispersive X-ray analysis, differential scanning calorimetry and transmission electron microscopy techniques.

  11. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-03-28

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity.

  12. TiO2 nanoparticle-induced ROS correlates with modulated immune cell function

    NASA Astrophysics Data System (ADS)

    Maurer-Jones, Melissa A.; Christenson, Jenna R.; Haynes, Christy L.

    2012-12-01

    Design of non-toxic nanoparticles will be greatly facilitated by understanding the nanoparticle-cell interaction mechanism on a cell function level. Mast cells are important cells for the immune system's first line of defense, and we can utilize their exocytotic behavior as a model cellular function as it is a conserved process across cell types and species. Perturbations in exocytosis can also have implications for whole organism health. One proposed mode of toxicity is nanoparticle-induced reactive oxygen species (ROS), particularly for titanium dioxide (TiO2) nanoparticles. Herein, we have correlated changes in ROS with the perturbation of the critical cell function of exocytosis, using UV light to induce greater levels of ROS in TiO2 exposed cells. The primary culture mouse peritoneal mast cells (MPMCs) were exposed to varying concentrations of TiO2 nanoparticles for 24 h. ROS content was determined using 2,7-dihydrodichlorofluorescein diacetate (DCFDA). Cellular viability was determined with the MTT and Trypan blue assays, and exocytosis was measured by the analytical electrochemistry technique of carbon-fiber microelectrode amperometry. MPMCs exposed to TiO2 nanoparticles experienced a dose-dependent increase in total ROS content. While there was minimal impact of ROS on cellular viability, there is a correlation between ROS amount and exocytosis perturbation. As nanoparticle-induced ROS increases, there is a significant decrease (45 %) in the number of serotonin molecules being released during exocytosis, increase (26 %) in the amount of time for each exocytotic granule to release, and decrease (28 %) in the efficiency of granule trafficking and docking. This is the first evidence that nanoparticle-induced ROS correlates with chemical messenger molecule secretion, possibly making a critical connection between functional impairment and mechanisms contributing to that impairment.

  13. Celastrol nanoparticles inhibit corneal neovascularization induced by suturing in rats

    PubMed Central

    Li, Zhanrong; Yao, Lin; Li, Jingguo; Zhang, Wenxin; Wu, Xianghua; Liu, Yi; Lin, Miaoli; Su, Wenru; Li, Yongping; Liang, Dan

    2012-01-01

    Purpose Celastrol, a traditional Chinese medicine, is widely used in anti-inflammation and anti-angiogenesis research. However, the poor water solubility of celastrol restricts its further application. This paper aims to study the effect of celastrol nanoparticles (CNPs) on corneal neovascularization (CNV) and determine the possible mechanism. Methods To improve the hydrophilicity of celastrol, celastrol-loaded poly(ethylene glycol)-block-poly(ɛ-caprolactone) nanopolymeric micelles were developed. The characterization of CNPs was measured by dynamic light scattering and transmission electron microscopy analysis. Celastrol loading content and release were assessed by ultraviolet-visible analysis and high performance liquid chromatography, respectively. In vitro, human umbilical vein endothelial cell proliferation and capillary-like tube formation were assayed. In vivo, suture-induced CNV was chosen to evaluate the effect of CNPs on CNV in rats. Immunohistochemistry for CD68 assessed the macrophage infiltration of the cornea on day 6 after surgery. Real-time quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay were used to evaluate the messenger ribonucleic acid and protein levels, respectively, of vascular endothelial growth factor, matrix metalloproteinase 9, and monocyte chemoattractant protein 1 in the cornea. Results The mean diameter of CNPs with spherical shape was 48 nm. The celastrol loading content was 7.36%. The release behavior of CNPs in buffered solution (pH 7.4) showed a typical two-phase release profile. CNPs inhibited the proliferation of human umbilical vein endothelial cells in a dose-independent manner and suppressed the capillary structure formation. After treatment with CNPs, the length and area of CNV reduced from 1.16 ± 0.18 mm to 0.49 ± 0.12 mm and from 7.71 ± 0.94 mm2 to 2.29 ± 0.61 mm2, respectively. Macrophage infiltration decreased significantly in the CNP-treated corneas. CNPs reduced

  14. Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples.

    PubMed

    Suslova, A; El-Atwani, O; Sagapuram, D; Harilal, S S; Hassanein, A

    2014-11-04

    Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER. One of the serious issues for PFCs is the high heat load during transient events such as ELMs and disruption in the reactor. Recrystallization and grain size growth in PFC materials caused by transients are undesirable changes in the material, since the isotropic microstructure developed after recrystallization exhibits a higher ductile-to-brittle transition temperature which increases with the grain size, a lower thermal shock fatigue resistance, a lower mechanical strength, and an increased surface roughening. The current work was focused on careful determination of the threshold parameters for surface recrystallization, grain growth rate, and thermal shock fatigue resistance under ELM-like transient heat events. Transient heat loads were simulated using long pulse laser beams for two different grades of ultrafine-grained tungsten. It was observed that cold rolled tungsten demonstrated better power handling capabilities and higher thermal stress fatigue resistance compared to severely deformed tungsten. Higher recrystallization threshold, slower grain growth, and lower degree of surface roughening were observed in the cold rolled tungsten.

  15. Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples

    PubMed Central

    Suslova, A.; El-Atwani, O.; Sagapuram, D.; Harilal, S. S.; Hassanein, A.

    2014-01-01

    Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER. One of the serious issues for PFCs is the high heat load during transient events such as ELMs and disruption in the reactor. Recrystallization and grain size growth in PFC materials caused by transients are undesirable changes in the material, since the isotropic microstructure developed after recrystallization exhibits a higher ductile-to-brittle transition temperature which increases with the grain size, a lower thermal shock fatigue resistance, a lower mechanical strength, and an increased surface roughening. The current work was focused on careful determination of the threshold parameters for surface recrystallization, grain growth rate, and thermal shock fatigue resistance under ELM-like transient heat events. Transient heat loads were simulated using long pulse laser beams for two different grades of ultrafine-grained tungsten. It was observed that cold rolled tungsten demonstrated better power handling capabilities and higher thermal stress fatigue resistance compared to severely deformed tungsten. Higher recrystallization threshold, slower grain growth, and lower degree of surface roughening were observed in the cold rolled tungsten. PMID:25366885

  16. Acute transient myopic shift induced by red wine: a case report.

    PubMed

    Liu, Ziyuan; Wang, Wei

    2015-01-01

    This case report described a patient presenting with unilateral transient myopic shift after consuming a lot of red wine. Ultrasound biomicroscopy detected annular shallow ciliary body detachment with supraciliary effusion, as well as a narrow chamber angle. The myopic shift was spontaneously resolved about one week after the onset without any treatment.

  17. Silica nanoparticles induce cardiotoxicity interfering with energetic status and Ca(2+) handling in adult rat cardiomyocytes.

    PubMed

    Guerrero-Beltrán, Carlos Enrique; Bernal-Ramírez, Judith; Lozano, Omar; Oropeza-Almazán, Yuriana; Castillo, Elena Cristina; Garza, Jesús Roberto; García, Noemí; Vela, Jorge; García-García, Alejandra; Ortega, Eduardo; Torre-Amione, Guillermo; Ornelas-Soto, Nancy; García-Rivas, Gerardo

    2017-04-01

    Recent evidence has shown that nanoparticles that have been used to improve or create new functional properties for common products may pose potential risks to human health. Silicon dioxide (SiO2) has emerged as a promising therapy vector for the heart. However, its potential toxicity and mechanisms of damage remain poorly understood. This study provides the first exploration of SiO2-induced toxicity in cultured cardiomyocytes exposed to 7- or 670-nm SiO2 particles. We evaluated the mechanism of cell death in isolated adult cardiomyocytes exposed to 24-h incubation. The SiO2 cell membrane association and internalization were analyzed. SiO2 showed a dose-dependent cytotoxic effect with a half-maximal inhibitory concentration for the 7 nm (99.5 ± 12.4 µg/ml) and 670 nm (>1,500 µg/ml) particles, which indicates size-dependent toxicity. We evaluated cardiomyocyte shortening and intracellular Ca(2+) handling, which showed impaired contractility and intracellular Ca(2+) transient amplitude during β-adrenergic stimulation in SiO2 treatment. The time to 50% Ca(2+) decay increased 39%, and the Ca(2+) spark frequency and amplitude decreased by 35 and 21%, respectively, which suggest a reduction in sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) activity. Moreover, SiO2 treatment depolarized the mitochondrial membrane potential and decreased ATP production by 55%. Notable glutathione depletion and H2O2 generation were also observed. These data indicate that SiO2 increases oxidative stress, which leads to mitochondrial dysfunction and low energy status; these underlie reduced SERCA activity, shortened Ca(2+) release, and reduced cell shortening. This mechanism of SiO2 cardiotoxicity potentially plays an important role in the pathophysiology mechanism of heart failure, arrhythmias, and sudden death.NEW & NOTEWORTHY Silica particles are used as novel nanotechnology-based vehicles for diagnostics and therapeutics for the heart. However, their potential hazardous effects remain

  18. Preparation of gold nanoparticle dimers via streptavidin-induced interlinking

    NASA Astrophysics Data System (ADS)

    Zon, Vera B.; Sachsenhauser, Matthias; Rant, Ulrich

    2013-10-01

    There is great interest in establishing efficient means of organizing nanoparticles into complex structures, especially in fields like nano-optical devices. One of the demonstrated routes uses biomolecular scaffolds, like the streptavidin-biotin system, to deterministically separate and structure particle complexes. However, controlled formation of streptavidin-linked nanoparticle dimers or trimers is challenging, and large aggregates are often formed under conditions that are difficult to regulate. Here, we studied the aggregates and interlinking kinetics of biotin-functionalized 20 nm gold nanoparticles in the presence of the interlinking protein, streptavidin. We found two different protein-linker concentration regions where small stable particle aggregates are formed: when the protein and nanoparticle concentrations are similar and when the protein to nanoparticle concentration ratio exceeds intermediate concentrations (10:1-100:1) that promote precipitation of large aggregates. We attribute this behavior to the limited availability of free-linker molecules and the limited availability of free ligand (biotin) on the particle surface for low and high protein concentrations, respectively. Furthermore, we show that the product can be additionally enriched up to 25 % through either centrifugation in sucrose or size-exclusion chromatography. These results provide additional understanding into the assembly of ligand-functionalized nanoparticles with water-soluble linkers and provide a facile way to produce well-defined small aggregates for potential use in, for instance, surface-enhanced spectroscopy.

  19. Chloride-inducible transient apoplastic alkalinizations induce stomata closure by controlling abscisic acid distribution between leaf apoplast and guard cells in salt-stressed Vicia faba.

    PubMed

    Geilfus, Christoph-Martin; Mithöfer, Axel; Ludwig-Müller, Jutta; Zörb, Christian; Muehling, Karl H

    2015-11-01

    Chloride stress causes the leaf apoplast transiently to alkalize, an event that is presumed to contribute to the ability of plants to adapt to saline conditions. However, the initiation of coordinated processes downstream of the alkalinization is unknown. We hypothesize that chloride-inducible pH dynamics are a key chemical feature modulating the compartmental distribution of abscisic acid (ABA) and, as a consequence, affecting stomata aperture. Apoplastic pH and stomata aperture dynamics in intact Vicia faba leaves were monitored by microscopy-based ratio imaging and porometric measurements of stomatal conductance. ABA concentrations in leaf apoplast and guard cells were compared with pH dynamics by gas-chromatography-mass-spectrometry (GC-MS) and liquid-chromatography-tandem-mass spectrometry (LC-MS/MS). Results demonstrate that, upon chloride addition to roots, an alkalizing factor that initiates the pH dynamic propagates from root to leaf in a way similar to xylem-distributed water. In leaves, it induces a systemic transient apoplastic alkalinization that causes apoplastic ABA concentration to increase, followed by an elevation of endogenous guard cell ABA. We conclude that the transient alkalinization, which is a remote effect of chloride stress, modulates the compartmental distribution of ABA between the leaf apoplast and the guard cells and, in this way, is instrumental in inducing stomata closure during the beginning of salinity.

  20. Laser-induced incandescence diagnostic for in situ monitoring of nanoparticle synthesis in an atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Mitrani, James; Patel, Shane; Shneider, Mikhail; Stratton, Brent; Raitses, Yevgeny

    2014-10-01

    A DC arc discharge with a consumed graphite electrode is commonly used for synthesis of carbon nanoaparticles in a low temperature (0.1-1 eV), atmospheric pressure plasma. The formation of nanoparticles in this plasma is poorly understood; it is not clear where nanoparticles nucleate and grow in the arc discharge. Therefore, a laser-induced incandescence (LII) diagnostic for in situ monitoring of the nanoparticles' spatial distribution in the plasma is currently being constructed. The LII diagnostic involves heating the particles with a short-pulsed laser, and measuring the induced spatiotemporal incandescence profiles on longer timescales. By appropriately modeling the induced spatiotemporal incandescence profiles, one can measure particle diameters and volume fraction. LII diagnostics have been extensively used to study soot particles in flames. However, they have never been applied in a strongly coupled plasma background. Even though the spatial dimensions for soot and nanoparticles are similar, great care is needed in developing an LII diagnostic for monitoring nanoparticles in a plasma background. Therefore, we will calibrate our LII diagnostic by measuring spatiotemporal incandescence profiles of known, research grade soot and nanoparticles. This work was supported by DOE Contract DE-AC02-09CH11466.

  1. Measuring charge transport from transient photovoltage rise times. A new tool to investigate electron transport in nanoparticle films.

    PubMed

    O'Regan, Brian C; Bakker, Klaas; Kroeze, Jessica; Smit, Herman; Sommeling, Paul; Durrant, James R

    2006-08-31

    Charge transport rate at open-circuit potential (V(oc)) is proposed as a new characterization method for dye-sensitized (DS) and other nanostructured solar cells. At V(oc), charge density is flat and measurable, which simplifies quantitative comparison of transport and charge density. Transport measured at V(oc) also allows meaningful comparison of charge transport rates between different treatments, temperatures, and types of cells. However, in typical DS cells, charge transport rates at V(oc) often cannot be measured by photocurrent transients or modulation techniques due to RC limitations and/or recombination losses. To circumvent this limitation, we show that charge transport at V(oc) can be determined directly from the transient photovoltage rise time using a simple, zero-free-parameter model. This method is not sensitive to RC limitation or recombination losses. In trap limited devices, such as DS cells, the comparison of transport rates between different devices or conditions is only valid when the Fermi level in the limiting conductor is at the same distance from the band edge. We show how to perform such comparisons, correcting for conduction band shifts using the density of states (DOS) distribution determined from the same photovoltage transients. Last we show that the relationship between measured transport rate and measured charge density is consistent with the trap limited transport model.

  2. Cerium and yttrium oxide nanoparticles against lead-induced oxidative stress and apoptosis in rat hippocampus.

    PubMed

    Hosseini, Asieh; Sharifi, Ali Mohammad; Abdollahi, Mohammad; Najafi, Rezvan; Baeeri, Maryam; Rayegan, Samira; Cheshmehnour, Jamshid; Hassani, Shokoufeh; Bayrami, Zahra; Safa, Majid

    2015-03-01

    Due to numerous industrial applications, lead has caused widespread pollution in the environment; it seems that the central nervous system (CNS) is the main target for lead in the human body. Oxidative stress and programmed cell death in the CNS have been assumed as two mechanisms related to neurotoxicity of lead. Cerium oxide (CeO2) and yttrium oxide (Y2O3) nanoparticles have recently shown antioxidant effects, particularly when used together, through scavenging the amount of reactive oxygen species (ROS) required for cell apoptosis. We looked into the neuroprotective effects of the combinations of these nanoparticles against acute lead-induced neurotoxicity in rat hippocampus. We used five groups in this study: control, lead, CeO2 nanoparticles + lead, Y2O3 nanoparticles + lead, and CeO2 and Y2O3 nanoparticles + lead. Nanoparticles of CeO2 (1000 mg/kg) and Y2O3 (230 mg/kg) were administered intraperitoneally during 2 days prior to intraperitoneal injection of the lead (25 mg/kg for 3 days). At the end of the treatments, oxidative stress markers, antioxidant enzymes activity, and apoptosis indexes were investigated. The results demonstrated that pretreatments with CeO2 and/or Y2O3 nanoparticles recovered lead-caused oxidative stress markers (ROS, lipid peroxidation, and total thiol molecules) and apoptosis indexes (Bax/Bcl-2 and caspase-3 protein expression). Besides, these nanoparticles reduced the activities of lead-induced superoxide dismutase and catalase as well as the ADP/ATP ratio. Interestingly, the best recovery resulted from the compound of these nanoparticles. Based on these outcomes, it appears that this combination may potentially be beneficial for protection against lead-caused acute toxicity in the brain through improving the oxidative stress-mediated programmed cell death pathway.

  3. Factors affecting T cell responses induced by fully synthetic glyco-gold-nanoparticles

    NASA Astrophysics Data System (ADS)

    Fallarini, Silvia; Paoletti, Tiziana; Battaglini, Carolina Orsi; Ronchi, Paolo; Lay, Luigi; Bonomi, Renato; Jha, Satadru; Mancin, Fabrizio; Scrimin, Paolo; Lombardi, Grazia

    2012-12-01

    We have synthesized and characterized nearly monodisperse and highly pure gold nanoparticles (2 and 5 nm) coated with non-immunoactive mono- and disaccharides, modelled after the capsular polysaccharide of serogroup A of the Neisseria meningitidis bacterium. We have used them to test their ability to induce immune cell responses as a consequence of their multivalency. The results indicate that they are indeed immunoactive and that immunoactivity is strongly dependent on size, and larger, 5 nm nanoparticles perform far better than smaller, 2 nm ones. Immune response (activation of macrophages) initiates with the whole nanoparticle recognition by the surface of antigen-presenting cells, independent of the saccharide oligomerization (or charge) on the nanoparticle surface. The induction of T cell proliferation and the increase of IL-2 levels, a consequence of the expression of MHC II involved in antigen presentation, require the presence of a disaccharide on the nanoparticle, not just a monosaccharide. A possible explanation is that, at this stage, the saccharides are detached from the gold surface. These results may provide leads for designing new saccharide-based, nanoparticle-conjugate vaccines.We have synthesized and characterized nearly monodisperse and highly pure gold nanoparticles (2 and 5 nm) coated with non-immunoactive mono- and disaccharides, modelled after the capsular polysaccharide of serogroup A of the Neisseria meningitidis bacterium. We have used them to test their ability to induce immune cell responses as a consequence of their multivalency. The results indicate that they are indeed immunoactive and that immunoactivity is strongly dependent on size, and larger, 5 nm nanoparticles perform far better than smaller, 2 nm ones. Immune response (activation of macrophages) initiates with the whole nanoparticle recognition by the surface of antigen-presenting cells, independent of the saccharide oligomerization (or charge) on the nanoparticle surface. The

  4. Cytosolic calcium transients are a determinant of contraction-induced HSP72 transcription in single skeletal muscle fibers.

    PubMed

    Stary, Creed M; Hogan, Michael C

    2016-05-15

    The intrinsic activating factors that induce transcription of heat shock protein 72 (HSP72) in skeletal muscle following exercise remain unclear. We hypothesized that the cytosolic Ca(2+) transient that occurs with depolarization is a determinant. We utilized intact, single skeletal muscle fibers from Xenopus laevis to test the role of the cytosolic Ca(2+) transient and several other exercise-related factors (fatigue, hypoxia, AMP kinase, and cross-bridge cycling) on the activation of HSP72 transcription. HSP72 and HSP60 mRNA levels were assessed with real-time quantitative PCR; cytosolic Ca(2+) concentration ([Ca(2+)]cyt) was assessed with fura-2. Both fatiguing and nonfatiguing contractions resulted in a significant increase in HSP72 mRNA. As expected, peak [Ca(2+)]cyt remained tightly coupled with peak developed tension in contracting fibers. Pretreatment with N-benzyl-p-toluene sulfonamide (BTS) resulted in depressed peak developed tension with stimulation, while peak [Ca(2+)]cyt remained largely unchanged from control values. Despite excitation-contraction uncoupling, BTS-treated fibers displayed a significant increase in HSP72 mRNA. Treatment of fibers with hypoxia (Po2: <3 mmHg) or AMP kinase activation had no effect on HSP72 mRNA levels. These results suggest that the intermittent cytosolic Ca(2+) transient that occurs with skeletal muscle depolarization provides a sufficient activating stimulus for HSP72 transcription. Metabolic or mechanical factors associated with fatigue development and cross-bridge cycling likely play a more limited role.

  5. Hypoxia-induced sensitisation of TRPA1 in painful dysesthesia evoked by transient hindlimb ischemia/reperfusion in mice.

    PubMed

    So, Kanako; Tei, Yuna; Zhao, Meng; Miyake, Takahito; Hiyama, Haruka; Shirakawa, Hisashi; Imai, Satoshi; Mori, Yasuo; Nakagawa, Takayuki; Matsubara, Kazuo; Kaneko, Shuji

    2016-03-17

    Dysesthesia is an unpleasant abnormal sensation, which is often accompanied by peripheral neuropathy or vascular impairment. Here, we examined the roles of transient receptor potential ankyrin 1 (TRPA1) in dysesthesia-like behaviours elicited by transient hindlimb ischemia (15-60 min) by tightly compressing the hindlimb, and reperfusion by releasing the ligature. The paw-withdrawal responses to tactile stimulation were reduced during ischemia and lasted for a while after reperfusion. Hindlimb ischemia/reperfusion elicited spontaneous licking of the ischemic hindpaw that peaked within 10 min. The licking was inhibited by reactive oxygen species (ROS) scavengers, a TRPA1 antagonist, or TRPA1 deficiency, but not by TRPV1 deficiency. In human TRPA1-expressing cells as well as cultured mouse dorsal root ganglion neurons, the H2O2-evoked TRPA1 response was significantly increased by pretreatment with hypoxia (80 mmHg) for 30 min. This hypoxia-induced TRPA1 sensitisation to H2O2 was inhibited by overexpressing a catalytically-inactive mutant of prolyl hydroxylase (PHD) 2 or in a TRPA1 proline mutant resistant to PHDs. Consistent with these results, a PHD inhibitor increased H2O2-evoked nocifensive behaviours through TRPA1 activation. Our results suggest that transient hindlimb ischemia/reperfusion-evoked spontaneous licking, i.e. painful dysesthesia, is caused by ROS-evoked activation of TRPA1 sensitised by hypoxia through inhibiting PHD-mediated hydroxylation of a proline residue in TRPA1.

  6. Plasmon-Induced Water Splitting Using Metallic-Nanoparticle-Loaded Photocatalysts and Photoelectrodes.

    PubMed

    Ueno, Kosei; Oshikiri, Tomoya; Misawa, Hiroaki

    2016-01-18

    Visible- and near-infrared-light-driven water splitting, which splits water molecules to generate hydrogen and oxygen gases, is a significant subject in artificial photosynthesis with the goal of achieving a low-carbon society. In recent years, considerable attention has been paid to studies on the development of a plasmon-induced water-splitting system responding to visible light. In this review, we categorized water-splitting systems as gold-nanoparticle-loaded semiconductor photocatalytic particles system and metallic-nanoparticles-loaded semiconductor photoelectrode systems, and introduce the latest studies according to these categories. Especially, we describe the studies that optimize a material or a structural design of metallic-nanoparticle-loaded semiconductor photoelectrodes and consider a whole water-splitting system, including a cathode design. Furthermore, we discuss important points when studying plasmon-induced water splitting, and we describe a methodology that enhances plasmon-induced water-splitting efficiency.

  7. Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

    DOE PAGES

    Bocharova, Vera; Sharp, Danna; Jones, Aaron; ...

    2015-03-09

    Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radiimore » in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.« less

  8. Oseltamivir (Tamiflu)-induced bilateral acute angle closure glaucoma and transient myopia

    PubMed Central

    Lee, Ji Woong; Lee, Ji Eun; Choi, Hee Young; Lee, Jong Soo

    2014-01-01

    A 27-year-old woman developed bilateral acute angle closure glaucoma (AACG) and transient myopia after taking oseltamivir for four days. On the fourth day, she received systemic and topical intraocular pressure (IOP)-lowering agents, and IOP decreased in both eyes. However, her visual acuity was unchanged. A myopic shift of -5.25 D OD and -5.0 D OS was estimated to have occurred in the acute phase. A-scan ultrasonography and Pentacam showed markedly shallow anterior chambers and increased lens thickness. Ultrasound biomicroscopy revealed an annular ciliochoroidal effusion with forward displacement of the lens-iris diaphragm. Ciliochoroidal effusion and transient myopia were resolved after discontinuation of oseltamivir. PMID:23571265

  9. Shock induced chemistry in liquids studied with ultrafast dynamic ellipsometry and visible transient absorption spectroscopy.

    PubMed

    Dang, N C; Bolme, C A; Moore, D S; McGrane, S D

    2012-10-25

    The response to ultrafast laser shock loading of nine liquids was monitored in an effort to reveal evidence of chemical changes occurring during the first 350 ps following the shock front. In an effort to compare molecular structures possessing a variety of common bonding patterns, data were acquired for the liquids: cyclohexane, cyclohexene, 1,3-cyclohexadiene, benzene, water, acetonitrile, acrylonitrile, tert-butylacetylene, and phenylacetylene. Transient absorption spectra were measured in the spectral region from 440 to 780 nm over shock stress states from 7 to 20 GPa. Ultrafast dynamic ellipsometry was used to measure the shock and particle velocity as well as the shocked refractive index. Significant transient absorption attributed to chemical reaction was observed for shocked phenylacetylene and acrylonitrile. Evidence of volume decreasing chemical reactions was also observed in the ultrafast dynamic ellipsometry data for phenylacetylene and acrylonitrile. The liquid 1,3-cyclohexadiene exhibited volume decreasing reaction in the ultrafast dynamic ellipsometry data but did not exhibit an increase in the transient absorption spectra. There was no evidence of chemical reaction in cyclohexane, cyclohexene, benzene, water, acetonitrile, or tert-butylacetylene in the first 350 ps, despite the application of shock stress that was in many cases well above the reaction threshold observed at microsecond time scales.

  10. Si nanoparticles as sensitizers for radio frequency-induced cancer hyperthermia

    NASA Astrophysics Data System (ADS)

    Kabashin, A. V.; Tamarov, K. P.; Ryabchikov, Yu. V.; Osminkina, L. A.; Zinovyev, S. V.; Kargina, J. V.; Gongalsky, M. B.; Al-Kattan, A.; Yakunin, V. G.; Sentis, M. L.; Ivanov, A. V.; Nikiforov, V. N.; Kanavin, A. P.; Zavestovskaya, I. N.; Timoshenko, V. Y.

    2016-03-01

    We review our recently obtained data on the employment of Si nanoparticles as sensitizers of radiofrequency (RF) - induced hyperthermia for mild cancer therapy tasks. Such an approach makes possible the heating of aqueous suspensions of Si nanoparticles by tens of degrees Celsius under relatively low intensities (1-5 W/cm2) of 27 MHz RF radiation. The heating effect is demonstrated for nanoparticles synthesized by laser ablation in water and mechanical grinding of porous silicon, while laser-ablated nanoparticles demonstrate a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations. The observed RF heating effect can be explained in the frame of a model considering the polarization of Si NPs and electrolyte in the external oscillating electromagnetic field and the corresponding release of heat by electric currents around the nanoparticles. Our tests evidence relative safety of Si nanostructures and their efficient dissolution in physiological solutions, suggesting potential clearance of nanoparticles from a living organism without any side effects. Profiting from Si nanoparticle-based heating, we finally demonstrate an efficient treatment of Lewis Lung carcinoma in vivo. The obtained data promise a breakthrough in the development of mild, non-invasive methods for cancer therapy.

  11. Noggin inhibits hypoxia-induced proliferation by targeting store-operated calcium entry and transient receptor potential cation channels.

    PubMed

    Yang, Kai; Lu, Wenju; Jia, Jing; Zhang, Jie; Zhao, Mingming; Wang, Sabrina; Jiang, Haiyang; Xu, Lei; Wang, Jian

    2015-06-01

    Abnormally elevated bone morphogenetic protein 4 (BMP4) expression and mediated signaling play a critical role in the pathogenesis of chronic hypoxia-induced pulmonary hypertension (CHPH). In this study, we investigated the expression level and functional significance of four reported naturally occurring BMP4 antagonists, noggin, follistatin, gremlin1, and matrix gla protein (MGP), in the lung and distal pulmonary arterial smooth muscle cell (PASMC). A 21-day chronic hypoxic (10% O2) exposure rat model was utilized, which has been previously shown to successfully establish experimental CHPH. Among the four antagonists, noggin, but not the other three, was selectively downregulated by hypoxic exposure in both the lung tissue and PASMC, in correlation with markedly elevated BMP4 expression, suggesting that the loss of noggin might account for the hypoxia-triggered BMP4 signaling transduction. Then, by using treatment of extrogenous recombinant noggin protein, we further found that noggin significantly normalized 1) BMP4-induced phosphorylation of cellular p38 and ERK1/2; 2) BMP4-induced phosphorylation of cellular JAK2 and STAT3; 3) hypoxia-induced PASMC proliferation; 4) hypoxia-induced store-operated calcium entry (SOCE), and 5) hypoxia-increased expression of transient receptor potential cation channels (TRPC1 and TRPC6) in PASMC. In combination, these data strongly indicated that the hypoxia-suppressed noggin accounts, at least partially, for hypoxia-induced excessive PASMC proliferation, while restoration of noggin may be an effective way to inhibit cell proliferation by suppressing SOCE and TRPC expression.

  12. Fucan-coated silver nanoparticles synthesized by a green method induce human renal adenocarcinoma cell death.

    PubMed

    Rocha Amorim, Monica Oliveira; Lopes Gomes, Dayanne; Dantas, Larisse Araujo; Silva Viana, Rony Lucas; Chiquetti, Samanta Cristina; Almeida-Lima, Jailma; Silva Costa, Leandro; Oliveira Rocha, Hugo Alexandre

    2016-12-01

    Polysaccharides containing sulfated L-fucose are often called fucans. The seaweed Spatoglossum schröederi synthesizes three fucans, among which fucan A is the most abundant. This polymer is not cytotoxic against various normal cell lines and is non-toxic to rats when administered at high doses. In addition, it exhibits low toxicity against tumor cells. With the aim of increasing the toxicity of fucan A, silver nanoparticles containing this polysaccharide were synthesized using a green chemistry method. The mean size of these nanoparticles was 210nm. They exhibited a spherical shape and negative surface charge and were stable for 14 months. When incubated with cells, these nanoparticles did not show any toxic effects against various normal cell lines; however, they decreased the viability of various tumor cells, especially renal adenocarcinoma cells 786-0. Flow cytometry analyses showed that the nanoparticles induced cell death responses of 786-0 cells through necrosis. Assays performed with several renal cell lines (HEK, VERO, MDCK) showed that these nanoparticles only induce death of 786-0 cells. The data obtained herein leads to the conclusion that fucan A nanoparticles are promising agents against renal adenocarcinoma.

  13. Defect-induced loading of Pt nanoparticles on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, Sung Jin; Park, Yong Jin; Ra, Eun Ju; Kim, Ki Kang; An, Kay Hyeok; Lee, Young Hee; Choi, Jae Young; Park, Chan Ho; Doo, Seok Kwang; Park, Min Ho; Yang, Cheol Woong

    2007-01-01

    Carbon nanotubes-supported Pt nanoparticles were loaded using a microwave oven on the defective carbon nanotubes generated by an additional oxidant during acid treatment. The authors' Raman spectra and x-ray diffraction analysis demonstrated that defects created during oxidation and microwave treatment acted as nucleation seeds for Pt adsorption. The generated Pt nanoparticles had the size distributions of 2-3nm and were uniformly distributed on the defects of carbon nanotubes. The authors' density functional calculations showed that the adsorption of Pt atom on the vacancy of nanotube was significantly stronger by s-p hybridization with carbon atoms near the defect site.

  14. Ultrasound-induced inertial cavitation from gas-stabilizing nanoparticles.

    PubMed

    Kwan, J J; Graham, S; Myers, R; Carlisle, R; Stride, E; Coussios, C C

    2015-08-01

    The understanding of cavitation from nanoparticles has been hindered by the inability to control nanobubble size. We present a method to manufacture nanoparticles with a tunable single hemispherical depression (nanocups) of mean diameter 90, 260, or 650 nm entrapping a nanobubble. A modified Rayleigh-Plesset crevice model predicts the inertial cavitation threshold as a function of cavity size and frequency, and is verified experimentally. The ability to tune cavitation nanonuclei and predict their behavior will be useful for applications ranging from cancer therapy to ultrasonic cleaning.

  15. Time-resolved laser-induced incandescence characterization of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Sipkens, T. A.; Singh, N. R.; Daun, K. J.

    2017-01-01

    This paper presents a comparative analysis of time-resolved laser-induced incandescence measurements of iron, silver, and molybdenum aerosols. Both the variation of peak temperature with fluence and the temperature decay curves strongly depend on the melting point and latent heat of vaporization of the nanoparticles. Recovered nanoparticle sizes are consistent with ex situ analysis, while thermal accommodation coefficients follow expected trends with gas molecular mass and structure. Nevertheless, there remain several unanswered questions and unexplained behaviors: the radiative properties of laser-energized iron nanoparticles do not match those of bulk molten iron; the absorption cross sections of molten iron and silver at the excitation laser wavelength exceed theoretical predictions; and there is an unexplained feature in the temperature decay of laser-energized molybdenum nanoparticles immediately following the laser pulse.

  16. High ordered biomineralization induced by carbon nanoparticles in the sea urchin Paracentrotus lividus.

    PubMed

    Manno, Daniela; Carata, Elisabetta; Tenuzzo, Bernadetta A; Panzarini, Elisa; Buccolieri, Alessandro; Filippo, Emanuela; Rossi, Marco; Serra, Antonio; Dini, Luciana

    2012-12-14

    A surprising and unexpected biomineralization process was observed during toxicological assessment of carbon nanoparticles on Paracentrotus lividus (sea urchin) pluteus larvae. The larvae activate a process of defense against external material, by incorporating the nanoparticles into microstructures of aragonite similarly to pearl oysters. Aiming at a better understanding of this phenomenon, the larvae were exposed to increasing concentrations of carbon nanoparticles and the biomineralization products were analyzed by electron microscopy, x-ray diffraction and Raman spectroscopy. In order to evaluate the possible influence of Sp-CyP-1 expression on this biomineralization process by larvae, analyses of gene expression (Sp-CyP-1) and calcein labeling were performed. Overall, we report experimental evidence about the capability of carbon nanoparticles to induce an increment of Sp-CyP-1 expression with the consequent activation of a biomineralization process leading to the production of a new pearl-like biomaterial never previously observed in sea urchins.

  17. High ordered biomineralization induced by carbon nanoparticles in the sea urchin Paracentrotus lividus

    NASA Astrophysics Data System (ADS)

    Manno, Daniela; Carata, Elisabetta; Tenuzzo, Bernadetta A.; Panzarini, Elisa; Buccolieri, Alessandro; Filippo, Emanuela; Rossi, Marco; Serra, Antonio; Dini, Luciana

    2012-12-01

    A surprising and unexpected biomineralization process was observed during toxicological assessment of carbon nanoparticles on Paracentrotus lividus (sea urchin) pluteus larvae. The larvae activate a process of defense against external material, by incorporating the nanoparticles into microstructures of aragonite similarly to pearl oysters. Aiming at a better understanding of this phenomenon, the larvae were exposed to increasing concentrations of carbon nanoparticles and the biomineralization products were analyzed by electron microscopy, x-ray diffraction and Raman spectroscopy. In order to evaluate the possible influence of Sp-CyP-1 expression on this biomineralization process by larvae, analyses of gene expression (Sp-CyP-1) and calcein labeling were performed. Overall, we report experimental evidence about the capability of carbon nanoparticles to induce an increment of Sp-CyP-1 expression with the consequent activation of a biomineralization process leading to the production of a new pearl-like biomaterial never previously observed in sea urchins.

  18. Alpha-alumina nanoparticles induce efficient autophagy-dependent cross-presentation and potent antitumour response

    NASA Astrophysics Data System (ADS)

    Li, Haiyan; Li, Yuhuan; Jiao, Jun; Hu, Hong-Ming

    2011-10-01

    Therapeutic cancer vaccination is an attractive strategy because it induces T cells of the immune system to recognize and kill tumour cells in cancer patients. However, it remains difficult to generate large numbers of T cells that can recognize the antigens on cancer cells using conventional vaccine carrier systems. Here we show that α-Al2O3 nanoparticles can act as an antigen carrier to reduce the amount of antigen required to activate T cells in vitro and in vivo. We found that α-Al2O3 nanoparticles delivered antigens to autophagosomes in dendritic cells, which then presented the antigens to T cells through autophagy. Immunization of mice with α-Al2O3 nanoparticles that are conjugated to either a model tumour antigen or autophagosomes derived from tumour cells resulted in tumour regression. These results suggest that α-Al2O3 nanoparticles may be a promising adjuvant in the development of therapeutic cancer vaccines.

  19. Dexmedetomidine Protects against Transient Global Cerebral Ischemia/Reperfusion Induced Oxidative Stress and Inflammation in Diabetic Rats

    PubMed Central

    Xing, Xichun; Wang, Qi; Li, Wenzhi

    2016-01-01

    Background Transient global cerebral ischemia/reperfusion (I/R) is a major perioperative complication, and diabetes increases the response of oxidative stress and inflammation induced by I/R. The objective of this study was to determine the protective effect of dexmedetomidine against transient global cerebral ischemia/reperfusion induced oxidative stress and inflammation in diabetic rats. Methods Sixty-four rats were assigned into four experimental groups: normoglycemia, normoglycemia + dexmedetomidine, hyperglycemia, and hyperglycemia + dexmedetomidine and all subsequent neurological examinations were evaluated by a blinded observer. Damage to the brain was histologically assessed using the TUNEL staining method while western blotting was used to investigate changes in the expression levels of apoptosis-related proteins as well as the microglia marker, ionized calcium-binding adapter molecule 1 (Iba1). Water content in the brain was also analyzed. In addition, hippocampal concentrations of malondialdehyde (MDA) and Nox2 (a member of the Nox family of NADPH oxidases), and the activity of superoxide dismutase and catalase were analyzed. Finally, changes in serum concentrations of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were detected. Results Results showed that diabetes increased brain water content, the number of apoptotic neurons, early neurological deficit scores, oxidative stress (MDA and Nox2) and inflammation (pro-inflammatory cytokines including TNF-α and IL-6) levels following transient global I/R injury, but that these symptoms were attenuated following administration of dexmedetomidine. Conclusions These findings suggest that dexmedetomidine can significantly alleviate damage resulting from I/R, and this mechanism may be related to a reduction in both oxidative stress and inflammation which is normally associated with I/R. PMID:26982373

  20. Estimating the timing and location of shallow rainfall-induced landslides using a model for transient, unsaturated infiltration

    USGS Publications Warehouse

    Baum, Rex L.; Godt, Jonathan W.; Savage, William Z.

    2010-01-01

    Shallow rainfall-induced landslides commonly occur under conditions of transient infiltration into initially unsaturated soils. In an effort to predict the timing and location of such landslides, we developed a model of the infiltration process using a two-layer system that consists of an unsaturated zone above a saturated zone and implemented this model in a geographic information system (GIS) framework. The model links analytical solutions for transient, unsaturated, vertical infiltration above the water table to pressure-diffusion solutions for pressure changes below the water table. The solutions are coupled through a transient water table that rises as water accumulates at the base of the unsaturated zone. This scheme, though limited to simplified soil-water characteristics and moist initial conditions, greatly improves computational efficiency over numerical models in spatially distributed modeling applications. Pore pressures computed by these coupled models are subsequently used in one-dimensional slope-stability computations to estimate the timing and locations of slope failures. Applied over a digital landscape near Seattle, Washington, for an hourly rainfall history known to trigger shallow landslides, the model computes a factor of safety for each grid cell at any time during a rainstorm. The unsaturated layer attenuates and delays the rainfall-induced pore-pressure response of the model at depth, consistent with observations at an instrumented hillside near Edmonds, Washington. This attenuation results in realistic estimates of timing for the onset of slope instability (7 h earlier than observed landslides, on average). By considering the spatial distribution of physical properties, the model predicts the primary source areas of landslides.

  1. Aging of TiO2 Nanoparticles Transiently Increases Their Toxicity to the Pelagic Microcrustacean Daphnia magna

    PubMed Central

    Seitz, Frank; Lüderwald, Simon; Rosenfeldt, Ricki R.; Schulz, Ralf; Bundschuh, Mirco

    2015-01-01

    During their aquatic life cycle, nanoparticles are subject to environmentally driven surface modifications (e.g. agglomeration or coating) associated with aging. Although the ecotoxicological potential of nanoparticles might be affected by these processes, only limited information about the potential impact of aging is available. In this context, the present study investigated acute (96 h) and chronic (21 d) implications of systematically aged titanium dioxide nanoparticles (nTiO2; ~90 nm) on the standard test species Daphnia magna by following the respective test guidelines. The nTiO2 were aged for 0, 1, 3 and 6 d in media with varying ionic strengths (Milli-Q water: approx. 0.00 mmol/L and ASTM: 9.25 mmol/L) in the presence or absence of natural organic matter (NOM). Irrespective of the other parameters, aging in Milli-Q did not change the acute toxicity relative to an unaged control. In contrast, 6 d aged nTiO2 in ASTM without NOM caused a fourfold decreased acute toxicity. Relative to the 0 d aged particles, nTiO2 aged for 1 and 3 d in ASTM with NOM, which is the most environmentally-relevant setup used here, significantly increased acute toxicity (by approximately 30%), while a toxicity reduction (60%) was observed for 6 d aged nTiO2. Comparable patterns were observed during the chronic experiments. A likely explanation for this phenomenon is that the aging of nTiO2 increases the particle size at the start of the experiment or the time of the water exchange from <100 nm to approximately 500 nm, which is the optimal size range to be taken up by filter feeding D. magna. If subjected to further agglomeration, larger nTiO2 particles, however, cannot be retained by the daphnids’ filter apparatus ultimately reducing their ecotoxicological potential. This non-linear pattern of increasing and decreasing nTiO2 related toxicity over the aging duration, highlights the knowledge gap regarding the underlying mechanisms and processes. This understanding seems, however

  2. DNA-PK is Involved in Repairing a Transient Surge of DNA BreaksInduced by Deceleration of DNA Replication.

    SciTech Connect

    Shimura, Tsutomu; Martin, Melvenia M.; Torres, Michael J.; Gu,Cory; Pluth, Janice M.; DiBernardi, Maria A.; McDonald, Jeffrey S.; Aladjem, Mirit I.

    2006-09-25

    ells that suffer substantial inhibition of DNA replication halt their cell cycle via a checkpoint response mediated by the PI3 kinases ATM and ATR. It is unclear how cells cope with milder replication insults, which are under the threshold for ATM and ATR activation. A third PI3 kinase, DNA-dependent protein kinase (DNA-PK), is also activated following replication inhibition, but the role DNA-PK might play in response to perturbed replication is unclear, since this kinase does not activate the signaling cascades involved in the S-phase checkpoint. Here we report that mild, transient drug-induced perturbation of DNA replication rapidly induced DNA breaks that promptly disappeared in cells that contained a functional DNA-PK whereas such breaks persisted in cells that were deficient in DNA-PK activity. After the initial transient burst of DNA breaks, cells with a functional DNA-PK did not halt replication and continued to synthesize DNA at a slow pace in the presence of replication inhibitors. In contrast, DNA-PK deficient cells subject to low levels of replication inhibition halted cell cycle progression via an ATR-mediated S-phase checkpoint. The ATM kinase was dispensable for the induction of the initial DNA breaks. These observations suggest that DNA-PK is involved in setting a high threshold for the ATR-Chkl-mediated S-phase checkpoint by promptly repairing DNA breaks that appear immediately following inhibition of DNA replication.

  3. Ultrafast light induced unusually broad transient absorption in the sub-bandgap region of GeSe2 thin film

    PubMed Central

    Barik, A. R.; Bapna, Mukund; Drabold, D. A.; Adarsh, K. V.

    2014-01-01

    In this paper, we show for the first time that ultrafast light illumination can induce an unusually broad transient optical absorption (TA), spanning of ≈ 200 nm in the sub-bandgap region of chalcogenide GeSe2 thin films, which we interpret as being a manifestation of creation and annihilation of light induced defects. Further, TA in ultrashort time scales show a maximum at longer wavelength, however blue shifts as time evolves, which provides the first direct evidence of the multiple decay mechanisms of these defects. Detailed global analysis of the kinetic data clearly demonstrates that two and three decay constants are required to quantitatively model the experimental data at ps and ns respectively. PMID:24418896

  4. Ultrafast light induced unusually broad transient absorption in the sub-bandgap region of GeSe2 thin film

    NASA Astrophysics Data System (ADS)

    Barik, A. R.; Bapna, Mukund; Drabold, D. A.; Adarsh, K. V.

    2014-01-01

    In this paper, we show for the first time that ultrafast light illumination can induce an unusually broad transient optical absorption (TA), spanning of ~ 200 nm in the sub-bandgap region of chalcogenide GeSe2 thin films, which we interpret as being a manifestation of creation and annihilation of light induced defects. Further, TA in ultrashort time scales show a maximum at longer wavelength, however blue shifts as time evolves, which provides the first direct evidence of the multiple decay mechanisms of these defects. Detailed global analysis of the kinetic data clearly demonstrates that two and three decay constants are required to quantitatively model the experimental data at ps and ns respectively.

  5. Enhancement of electron-positron pair creation due to transient excitation of field-induced bound states

    NASA Astrophysics Data System (ADS)

    Jiang, M.; Lv, Q. Z.; Sheng, Z. M.; Grobe, R.; Su, Q.

    2013-04-01

    We study the creation of electron-positron pairs induced by two spatially separated electric fields that vary periodically in time. The results are based on large-scale computer simulations of the time-dependent Dirac equation in reduced spatial dimensions. When the separation of the fields is very large, the pair creation is caused by multiphoton transitions and mainly determined by the frequency of the fields. However, for small spatial separations a coherence effect can be observed that can enhance or reduce the particle yield compared to the case of two infinitely separated fields. If the travel time for a created electron or positron between both field locations becomes comparable to the period of the oscillating fields, we observe peaks in the energy spectrum which can be explained in terms of field-induced transient bound states.

  6. Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

    NASA Astrophysics Data System (ADS)

    Lopez-Arce, Paula; Zornoza-Indart, Ainara

    2015-09-01

    Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast-sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

  7. Virus inhibition induced by polyvalent nanoparticles of different sizes

    NASA Astrophysics Data System (ADS)

    Vonnemann, Jonathan; Sieben, Christian; Wolff, Christopher; Ludwig, Kai; Böttcher, Christoph; Herrmann, Andreas; Haag, Rainer

    2014-01-01

    The development of antiviral agents is one of the major challenges in medical science. So far, small monovalent molecular drugs that inhibit the late steps in the viral replication cycle, i.e., virus budding, have not worked well which emphasizes the need for alternative approaches. Polyvalently presented viral receptors, however, show potential as good inhibitors of virus-cell binding, which is the first step in the viral infection cycle. By gradually increasing the size of ligand functionalized gold nanoparticles, up to virus-like dimensions, we are now able to quantify the polyvalent enhancement of virus-cell binding inhibition and to identify varying mechanisms of virus inhibition with different efficacies: by employing a new binding assay we found that surface area-normalized polysulfated gold nanoparticles of diameters equal to and larger than the virus diameter (>50 nm) more efficiently inhibit the binding of vesicular stomatitis virus (VSV) to cells than smaller particles. On a per particle basis, larger sized gold nanoparticles were surprisingly shown to inhibit the viral infection up to two orders of magnitude more efficiently than smaller particles, which suggests different mechanisms of virus inhibition. Based on complementary electron microscopic data, we noticed that larger gold nanoparticles act as efficient cross-linkers between virions, whereas smaller gold nanoparticles decorate the surface of individual virus particles. Our systematic study accentuates the need for the design of biodegradable, virus-sized inhibitors capitalizing on polyvalent binding.The development of antiviral agents is one of the major challenges in medical science. So far, small monovalent molecular drugs that inhibit the late steps in the viral replication cycle, i.e., virus budding, have not worked well which emphasizes the need for alternative approaches. Polyvalently presented viral receptors, however, show potential as good inhibitors of virus-cell binding, which is the

  8. Terahertz emission from two-plasmon-decay induced transient currents in laser-solid interactions

    SciTech Connect

    Liao, G.-Q.; Li, C.; Li, Y.-T. E-mail: zmsheng@sjtu.edu.cn; Wang, W.-M.; Mondal, S.; Hafez, H. A.; Fareed, M. A.; Ozaki, T.; Sheng, Z.-M. E-mail: zmsheng@sjtu.edu.cn; Zhang, J.

    2016-01-15

    We have studied the generation of terahertz (THz) radiation via the interaction of intense femtosecond laser pulses with solid targets at a small incidence angle. It is found that preplasma with a moderate density gradient can enhance the emission. We also observe saturation of the THz output with the driving laser energy. We find that THz emission is closely related to the 3/2 harmonics of the driving laser. Particle-in-cell simulations indicate that under the present experimental conditions, the THz emission could be attributed to the transient currents at the plasma-vacuum interface, mainly formed by the two-plasmon-decay instability.

  9. Transient thyrotoxicosis from thyroiditis induced by sibutramine overdose: a case report.

    PubMed

    Kim, S K; Lee, S M; Yoo, S S; Hahm, J R; Jung, J H; Kim, H S; Kim, S; Chung, S I; Jung, T S

    2013-08-01

    Sibutramine is an antiobesity drug that inhibits the reuptake of serotonin and noradrenalin in the hypothalamus. A 37-year-old Korean man presented to the emergency room for the oral intake of 280 mg of sibutramine. The patient was in thyrotoxic state. The (99m)Technetium-pertechnetate thyroid scan showed irregular uptake of radioisotope and thyroid-stimulating hormone receptor antibody and thyroperoxidase antibody were negative. Thyroid function normalized after that. The patient had transient thyrotoxicosis with thyroiditis. We report a case of thyrotoxicosis accompanied by thyroiditis resulting from the intentional overdose of sibutramine.

  10. Breast cancer therapy by laser-induced Coulomb explosion of gold nanoparticles

    PubMed Central

    Ashiq, Muhammad Gul Bahar; Tahir, Bashir Ahmad; Ibrahim, Noorddin; Nadeem, Muhammad

    2013-01-01

    Objective Laser-induced Coulomb explosion of gold nanoparticles for breast cancer has been studied by nanophotolysis technique. This study aimed to investigate whether laser-induced bubble formation due to Coulomb explosion can provide an effective approach for selective damage of breast cancer with gold nanoparticles. Method Numerical method involves laser-induced Coulomb explosion of gold nanoparticles. Different parameters related to nanophotolysis such as laser fluence, tumor depth, cluster radius, laser pulse duration, and bubble formation is studied numerically. Numerical simulation was performed using Mat lab. Results The gold nanoparticles of 10, 20, 30, 40, and 50 nm in radius could penetrate into tumor 1.14, 1.155, 1.189, 1.20 and 1.22 cm in depth respectively. The maximum penetration depth in tumor could be obtained with nanoparticles of 50 nm radius. Short laser pulse of 40 ns with nanoparticles of 10 nm radius could penetrate into tumor 1.14 cm in depth. Bubbles with a radius of 9 µm could effectively kill breast cancer cells without damaging healthy ones. The bubble radius increased from 4 to 9 µm with an increase in pulse duration in the range of 10 to 30 ns. Conclusions Gold nanoparticles with increasing radius and bubble formation for selective damage of breast cancer cells are successfully probed. The present calculated results are compared with other experimental findings, and good correlation is found between the present work and previous experimental values. It was demonstrated that bubble formation in tumor may further increase the efficacy of breast cancer treatment. PMID:24385705

  11. Endotoxin Induces Fibrosis in Vascular Endothelial Cells through a Mechanism Dependent on Transient Receptor Protein Melastatin 7 Activity

    PubMed Central

    Echeverría, Cesar; Montorfano, Ignacio; Hermosilla, Tamara; Armisén, Ricardo; Velásquez, Luis A.; Cabello-Verrugio, Claudio; Varela, Diego; Simon, Felipe

    2014-01-01

    The pathogenesis of systemic inflammatory diseases, including endotoxemia-derived sepsis syndrome, is characterized by endothelial dysfunction. It has been demonstrated that the endotoxin lipopolysaccharide (LPS) induces the conversion of endothelial cells (ECs) into activated fibroblasts through endothelial­to­mesenchymal transition mechanism. Fibrogenesis is highly dependent on intracellular Ca2+ concentration increases through the participation of calcium channels. However, the specific molecular identity of the calcium channel that mediates the Ca2+ influx during endotoxin-induced endothelial fibrosis is still unknown. Transient receptor potential melastatin 7 (TRPM7) is a calcium channel that is expressed in many cell types, including ECs. TRPM7 is involved in a number of crucial processes such as the conversion of fibroblasts into activated fibroblasts, or myofibroblasts, being responsible for the development of several characteristics of them. However, the role of the TRPM7 ion channel in endotoxin-induced endothelial fibrosis is unknown. Thus, our aim was to study whether the TRPM7 calcium channel participates in endotoxin-induced endothelial fibrosis. Using primary cultures of ECs, we demonstrated that TRPM7 is a crucial protein involved in endotoxin-induced endothelial fibrosis. Suppression of TRPM7 expression protected ECs from the fibrogenic process stimulated by endotoxin. Downregulation of TRPM7 prevented the endotoxin-induced endothelial markers decrease and fibrotic genes increase in ECs. In addition, TRPM7 downregulation abolished the endotoxin-induced increase in ECM proteins in ECs. Furthermore, we showed that intracellular Ca2+ levels were greatly increased upon LPS challenge in a mechanism dependent on TRPM7 expression. These results demonstrate that TRPM7 is a key protein involved in the mechanism underlying endotoxin-induced endothelial fibrosis. PMID:24710004

  12. Endotoxin induces fibrosis in vascular endothelial cells through a mechanism dependent on transient receptor protein melastatin 7 activity.

    PubMed

    Echeverría, Cesar; Montorfano, Ignacio; Hermosilla, Tamara; Armisén, Ricardo; Velásquez, Luis A; Cabello-Verrugio, Claudio; Varela, Diego; Simon, Felipe

    2014-01-01

    The pathogenesis of systemic inflammatory diseases, including endotoxemia-derived sepsis syndrome, is characterized by endothelial dysfunction. It has been demonstrated that the endotoxin lipopolysaccharide (LPS) induces the conversion of endothelial cells (ECs) into activated fibroblasts through endothelial-to-mesenchymal transition mechanism. Fibrogenesis is highly dependent on intracellular Ca2+ concentration increases through the participation of calcium channels. However, the specific molecular identity of the calcium channel that mediates the Ca2+ influx during endotoxin-induced endothelial fibrosis is still unknown. Transient receptor potential melastatin 7 (TRPM7) is a calcium channel that is expressed in many cell types, including ECs. TRPM7 is involved in a number of crucial processes such as the conversion of fibroblasts into activated fibroblasts, or myofibroblasts, being responsible for the development of several characteristics of them. However, the role of the TRPM7 ion channel in endotoxin-induced endothelial fibrosis is unknown. Thus, our aim was to study whether the TRPM7 calcium channel participates in endotoxin-induced endothelial fibrosis. Using primary cultures of ECs, we demonstrated that TRPM7 is a crucial protein involved in endotoxin-induced endothelial fibrosis. Suppression of TRPM7 expression protected ECs from the fibrogenic process stimulated by endotoxin. Downregulation of TRPM7 prevented the endotoxin-induced endothelial markers decrease and fibrotic genes increase in ECs. In addition, TRPM7 downregulation abolished the endotoxin-induced increase in ECM proteins in ECs. Furthermore, we showed that intracellular Ca2+ levels were greatly increased upon LPS challenge in a mechanism dependent on TRPM7 expression. These results demonstrate that TRPM7 is a key protein involved in the mechanism underlying endotoxin-induced endothelial fibrosis.

  13. Ca(2+) and Calpain Mediate Capsaicin-induced Ablation of Axonal Terminals Expressing Transient Receptor Potential Vanilloid 1.

    PubMed

    Wang, Sheng; Wang, Sen; Asgar, Jamila; Joseph, John; Ro, Jin Y; Wei, Feng; Campbell, James N; Chung, Man-Kyo

    2017-03-30

    Capsaicin is an ingredient in spicy peppers that produces burning pain by activating transient receptor potential vanilloid 1 (TRPV1), a Ca2+-permeable ion channel in nociceptors. Capsaicin also has been used as an analgesic, and its topical administration is approved for the treatment of certain pain conditions. The mechanisms underlying capsaicin-induced analgesia likely involve reversible ablation of nociceptor terminals. However, the mechanisms underlying these effects are not well understood. To visualize TRPV1-lineage axons, a genetically engineered mouse model was used in which a fluorophore is expressed under TRPV1 promoter. Using a combination of these TRPV1-lineage reporter mice and primary afferent cultures, we monitored capsaicin-induced effects on afferent terminals in real time. We found that Ca2+ influx through TRPV1 is necessary for capsaicin-induced ablation of nociceptive terminals. Although capsaicin-induced mitochondrial Ca2+ uptake was TRPV1-dependent, dissipation of the mitochondrial membrane potential, inhibition of the mitochondrial transition permeability pore and scavengers of reactive oxygen species did not attenuate capsaicin-induced ablation. In contrast, MDL28170, an inhibitor of the Ca2+-dependent protease calpain diminished ablation. Furthermore, overexpression of calpastatin, an endogenous inhibitor of calpain, or knockdown of calpain2 also decreased the ablation. Quantitative assessment of TRPV1-lineage afferents in the epidermis of the hind paws of the reporter mice showed that EGTA and MDL28170 diminished capsaicin-induced ablation. Moreover, MDL28170 prevented capsaicin-induced thermal hypoalgesia. These results suggest that TRPV1/Ca2+/calpain-dependent signaling plays a dominant role in capsaicin-induced ablation of nociceptive terminals and further our understanding of the molecular mechanisms underlying effects of capsaicin on nociceptors.

  14. Plasmonic electromagnetically induced transparency in metallic nanoparticle-quantum dot hybrid systems

    NASA Astrophysics Data System (ADS)

    Hatef, Ali; Sadeghi, Seyed M.; Singh, Mahi R.

    2012-02-01

    We study the variation of the energy absorption rate in a hybrid semiconductor quantum dot-metallic nanoparticle system doped in a photonic crystal. The quantum dot is taken as a three-level V-configuration system and is driven by two applied fields (probe and control). We consider that one of the excitonic resonance frequencies is near to the plasmonic resonance frequency of the metallic nanoparticle, and is driven by the probe field. The other excitonic resonance frequency is far from both the plasmonic resonance frequency and the photonic bandgap edge, and is driven by the control field. In the absence of the photonic crystal we found that the system supports three excitonic-induced transparencies in the energy absorption spectrum of the metallic nanoparticle. We show that the photonic crystal allows us to manipulate the frequencies of such excitonic-induced transparencies and the amplitude of the energy absorption rate.

  15. Transient turbid water mass reduces temperature-induced coral bleaching and mortality in Barbados.

    PubMed

    Oxenford, Hazel A; Vallès, Henri

    2016-01-01

    Global warming is seen as one of the greatest threats to the world's coral reefs and, with the continued rise in sea surface temperature predicted into the future, there is a great need for further understanding of how to prevent and address the damaging impacts. This is particularly so for countries whose economies depend heavily on healthy reefs, such as those of the eastern Caribbean. Here, we compare the severity of bleaching and mortality for five dominant coral species at six representative reef sites in Barbados during the two most significant warm-water events ever recorded in the eastern Caribbean, i.e., 2005 and 2010, and describe prevailing island-scale sea water conditions during both events. In so doing, we demonstrate that coral bleaching and subsequent mortality were considerably lower in 2010 than in 2005 for all species, irrespective of site, even though the anomalously warm water temperature profiles were very similar between years. We also show that during the 2010 event, Barbados was engulfed by a transient dark green turbid water mass of riverine origin coming from South America. We suggest that reduced exposure to high solar radiation associated with this transient water mass was the primary contributing factor to the lower bleaching and mortality observed in all corals. We conclude that monitoring these episodic mesoscale oceanographic features might improve risk assessments of southeastern Caribbean reefs to warm-water events in the future.

  16. Photo-induced dynamics in heterocyclic aromatic molecules probed by femtosecond XUV transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Lackner, Florian; Chatterley, Adam S.; Pemmaraju, Chaitanya D.; Neumark, Daniel M.; Leone, Stephen R.; Gessner, Oliver

    2016-05-01

    We report on the ring-opening and dissociation dynamics of strong-field ionized selenophene (C4 H4 Se), studied by transient XUV absorption spectroscopy at the Se 3d edge. The table-top experiments are facilitated by high-order harmonic generation coupled with a gas phase transient XUV absorption setup that is optimized for the study of organic compounds. Employing element-specific core-to-valence transitions, the ultrafast molecular dynamics are monitored from the perspective of the well-localized Se atoms. Spectral features are assigned based on first principles TDDFT calculations for a large manifold of electronic states. We observe signatures of rapidly (~ 35 fs) decaying highly excited molecular cations, the formation of ring-opened products on a 100 fs time scale and, most notably, the elimination of bare Se+ ions in a very rapid multi-step process. A delayed onset of the Se+ ions provides direct evidence that both selenium-carbon bonds are broken within only ~ 130 fs and that a sequential mechanism, presumably an initial ring-opening followed by a subsequent breaking of the second bond, is required to eliminate the atomic fragments.

  17. Transient turbid water mass reduces temperature-induced coral bleaching and mortality in Barbados

    PubMed Central

    Vallès, Henri

    2016-01-01

    Global warming is seen as one of the greatest threats to the world’s coral reefs and, with the continued rise in sea surface temperature predicted into the future, there is a great need for further understanding of how to prevent and address the damaging impacts. This is particularly so for countries whose economies depend heavily on healthy reefs, such as those of the eastern Caribbean. Here, we compare the severity of bleaching and mortality for five dominant coral species at six representative reef sites in Barbados during the two most significant warm-water events ever recorded in the eastern Caribbean, i.e., 2005 and 2010, and describe prevailing island-scale sea water conditions during both events. In so doing, we demonstrate that coral bleaching and subsequent mortality were considerably lower in 2010 than in 2005 for all species, irrespective of site, even though the anomalously warm water temperature profiles were very similar between years. We also show that during the 2010 event, Barbados was engulfed by a transient dark green turbid water mass of riverine origin coming from South America. We suggest that reduced exposure to high solar radiation associated with this transient water mass was the primary contributing factor to the lower bleaching and mortality observed in all corals. We conclude that monitoring these episodic mesoscale oceanographic features might improve risk assessments of southeastern Caribbean reefs to warm-water events in the future. PMID:27326377

  18. Laser induced inverse Landau damping in metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Garcia, Martin E.; Castro, Alberto; Alonso, J. A.; Rubio, Angel

    2002-03-01

    We perform real space time-dependent density functional calculations to study the response of small metallic nanoparticles to femtosecond laser pulses. In particular, we analyze the role of screening effects for different laser pulse intensities and frequencies. Calculations are performed on sodium clusters using both the Jellium model and pseudopitentials Based on our results we predict that, if a pulse of sufficiently high intensity ( > 10^14 W/cm^2) excites a single-particle state of the nanoparticle, the response of the system involves both the single-particle- and the surface-plasmon states. We argue that this creation of plasmons from the decay of single-particle excitations, which can be viewed as the inverse of the well known Landau-damping effect, is related to the time-evolution of the screening of charge fluctuations.

  19. Nanoparticle Enhanced Laser Induced Breakdown Spectroscopy for Improving the Detection of Molecular Bands

    NASA Astrophysics Data System (ADS)

    Koral, Can; De Giacomo, Alessandro; Mao, Xianglei; Zorba, Vassilia; Russo, Richard E.

    2016-11-01

    Enhancement of molecular band emission in laser-induced plasmas is important for improving sensitivity and limits of detection in molecular sensing and molecular isotope analysis. In this work we introduce the use of Nanoparticle Enhanced Laser Induced Breakdown (NELIBS) for the enhancement of molecular band emission in laser-induced plasmas, and study the underlying mechanisms responsible for the observed enhancement. The use of Ag nanoparticles leads to an order of magnitude enhancement for AlO (B2Σ+ → Χ+ Σ+) system emission from an Al-based alloy. We demonstrate that the mechanism responsible for the enhancement of molecular bands differs from that of atomic emission, and can be traced down to the increased number of atomic species in NELIBS which lead to AlO molecular formation. These findings showcase the potential of NELIBS as a simple and viable technology for enhancing molecular band emission in laser-induced plasmas.

  20. Thermal induced structural transformation of bimetallic AuPd nanoparticles

    NASA Astrophysics Data System (ADS)

    Bruma, A.; Li, Z. Y.

    2014-06-01

    High Angle Annular Dark Field Scanning Transmission Electron Microscope (HAADF-STEM) has been employed for the study of thermal effects of structural transformation of AuPd nanoparticles produced by physical vapour deposition. Depending on the duration of annealing at a temperature of 500 K, atomic resolved imaging analysis reveals the formation of various structure morphologies from the ordered L12 superlattice to the core-shell structure. The effects of Pd-oxides are also discussed.

  1. Hypoxia-induced sensitisation of TRPA1 in painful dysesthesia evoked by transient hindlimb ischemia/reperfusion in mice

    PubMed Central

    So, Kanako; Tei, Yuna; Zhao, Meng; Miyake, Takahito; Hiyama, Haruka; Shirakawa, Hisashi; Imai, Satoshi; Mori, Yasuo; Nakagawa, Takayuki; Matsubara, Kazuo; Kaneko, Shuji

    2016-01-01

    Dysesthesia is an unpleasant abnormal sensation, which is often accompanied by peripheral neuropathy or vascular impairment. Here, we examined the roles of transient receptor potential ankyrin 1 (TRPA1) in dysesthesia-like behaviours elicited by transient hindlimb ischemia (15–60 min) by tightly compressing the hindlimb, and reperfusion by releasing the ligature. The paw-withdrawal responses to tactile stimulation were reduced during ischemia and lasted for a while after reperfusion. Hindlimb ischemia/reperfusion elicited spontaneous licking of the ischemic hindpaw that peaked within 10 min. The licking was inhibited by reactive oxygen species (ROS) scavengers, a TRPA1 antagonist, or TRPA1 deficiency, but not by TRPV1 deficiency. In human TRPA1-expressing cells as well as cultured mouse dorsal root ganglion neurons, the H2O2-evoked TRPA1 response was significantly increased by pretreatment with hypoxia (80 mmHg) for 30 min. This hypoxia-induced TRPA1 sensitisation to H2O2 was inhibited by overexpressing a catalytically-inactive mutant of prolyl hydroxylase (PHD) 2 or in a TRPA1 proline mutant resistant to PHDs. Consistent with these results, a PHD inhibitor increased H2O2-evoked nocifensive behaviours through TRPA1 activation. Our results suggest that transient hindlimb ischemia/reperfusion-evoked spontaneous licking, i.e. painful dysesthesia, is caused by ROS-evoked activation of TRPA1 sensitised by hypoxia through inhibiting PHD-mediated hydroxylation of a proline residue in TRPA1. PMID:26983498

  2. Titanium dioxide nanoparticles induce an adaptive inflammatory response and invasion and proliferation of lung epithelial cells in chorioallantoic membrane

    SciTech Connect

    Medina-Reyes, Estefany I.; Déciga-Alcaraz, Alejandro; Freyre-Fonseca, Verónica; Delgado-Buenrostro, Norma L.; Flores-Flores, José O.; Sánchez-Pérez, Yesennia; García-Cuéllar, Claudia M.; and others

    2015-01-15

    Titanium dioxide nanoparticles (TiO{sub 2} NPs) studies have been performed using relatively high NPs concentration under acute exposure and limited studies have compared shape effects. We hypothesized that midterm exposure to low TiO{sub 2} NPs concentration in lung epithelial cells induces carcinogenic characteristics modulated partially by NPs shape. To test our hypothesis we synthesized NPs shaped as belts (TiO{sub 2}-B) using TiO{sub 2} spheres (TiO{sub 2}-SP) purchased from Sigma Aldrich Co. Then, lung epithelial A549 cells were low-exposed (10 µg/cm{sup 2}) to both shapes during 7 days and internalization, cytokine release and invasive potential were determined. Results showed greater TiO{sub 2}-B effect on agglomerates size, cell size and granularity than TiO{sub 2}-SP. Agglomerates size in cell culture medium was 310 nm and 454 nm for TiO{sub 2}-SP and TiO{sub 2}-B, respectively; TiO{sub 2}-SP and TiO{sub 2}-B induced 23% and 70% cell size decrease, respectively, whilst TiO{sub 2}-SP and TiO{sub 2}-B induced 7 and 14-fold of granularity increase. NO{sub x} production was down-regulated (31%) by TiO{sub 2}-SP and up-regulated (70%) by TiO{sub 2}-B. Both NPs induced a transient cytokine release (IL-2, IL-6, IL-8, IL-4, IFN-γ, and TNF-α) after 4 days, but cytokines returned to basal levels in TiO{sub 2}-SP exposed cells while TiO{sub 2}-B induced a down-regulation after 7 days. Midterm exposure to both shapes of NPs induced capability to degrade cellular extracellular matrix components from chorioallantoic membrane and Ki-67 marker showed that TiO{sub 2}-B had higher proliferative potential than TiO{sub 2}-SP. We conclude that midterm exposure to low NPs concentration of NPs has an impact in the acquisition of new characteristics of exposed cells and NPs shape influences cellular outcome. - Graphical abstract: (A) Lung epithelial cells were low exposed (below 10 µg/cm{sup 2}) to titanium dioxide nanoparticles (TiO{sub 2}-NPs) shaped as spheres (TiO{sub 2

  3. Ginger-derived nanoparticles protect against alcohol-induced liver damage

    PubMed Central

    Zhuang, Xiaoying; Deng, Zhong-Bin; Mu, Jingyao; Zhang, Lifeng; Yan, Jun; Miller, Donald; Feng, Wenke; McClain, Craig J.; Zhang, Huang-Ge

    2015-01-01

    Daily exposure of humans to nanoparticles from edible plants is inevitable, but significant advances are required to determine whether edible plant nanoparticles are beneficial to our health. Additionally, strategies are needed to elucidate the molecular mechanisms underlying any beneficial effects. Here, as a proof of concept, we used a mouse model to show that orally given nanoparticles isolated from ginger extracts using a sucrose gradient centrifugation procedure resulted in protecting mice against alcohol-induced liver damage. The ginger-derived nanoparticle (GDN)–mediated activation of nuclear factor erythroid 2-related factor 2 (Nrf2) led to the expression of a group of liver detoxifying/antioxidant genes and inhibited the production of reactive oxygen species, which partially contributes to the liver protection. Using lipid knock-out and knock-in strategies, we further identified that shogaol in the GDN plays a role in the induction of Nrf2 in a TLR4/TRIF-dependent manner. Given the critical role of Nrf2 in modulating numerous cellular processes, including hepatocyte homeostasis, drug metabolism, antioxidant defenses, and cell-cycle progression of liver, this finding not only opens up a new avenue for investigating GDN as a means to protect against the development of liver-related diseases such as alcohol-induced liver damage but sheds light on studying the cellular and molecular mechanisms underlying interspecies communication in the liver via edible plant–derived nanoparticles. PMID:26610593

  4. Thiol-Ene Induced Diphosphonic Acid Functionalization of Superparamagnetic Iron Oxide Nanoparticles

    SciTech Connect

    Rutledge, Ryan D.; Warner, Cynthia L.; Pittman, Jonathan W.; Addleman, Raymond S.; Engelhard, Mark H.; Chouyyok, Wilaiwan; Warner, Marvin G.

    2010-07-20

    Multi-functional organic molecules represent an interesting challenge for nanoparticle functionalization due to the potential for undesirable interactions between the substrate material and the variable functionalities, making it difficult to control the final orientation of the ligand. In the present study, UV-induced thiol-ene click chemistry has been utilized as a means of directed functionalization of bifunctional ligands on an iron oxide nanoparticle surface. Allyl diphosphonic acid ligand was covalently deposited on the surface of thiol-presenting iron oxide nanoparticles via the formation of a UV-induced thioether. This method of thiol-ene click chemistry offers a set of reaction conditions capable of controlling the ligand deposition and circumventing the natural affinity exhibited by the phosphonic acid moiety for the iron oxide surface. These claims are supported via a multimodal characterization platform which includes thermogravimetric analysis, x-ray photoelectron spectroscopy, and metal contact analysis and are consistent with a properly oriented, highly active ligand on the nanoparticle surface. These experiments suggest thiol-ene click chemistry as both a practical and generally applicable strategy for the directed deposition of multi-functional ligands on metal oxide nanoparticle surfaces.

  5. Transient unidirectional energy flow and diode-like phenomenon induced by non-Markovian environments

    PubMed Central

    Jing, Jun; Segal, Dvira; Li, Baowen; Wu, Lian-Ao

    2015-01-01

    Relying on an exact time evolution scheme, we identify a novel transient energy transfer phenomenon in an exactly-solvable quantum microscopic model consisting of a three-level system coupled to two non-Markovian zero-temperature bosonic baths through two separable quantum channels. The dynamics of this model can be solved exactly using the quantum-state-diffusion equation formalism, demonstrating finite intervals of unidirectional energy flow across the system, typically, from the non-Markovian environment towards the more Markovian bath. Furthermore, when introducing a spatial asymmetry into the system, an analogue of the rectification effect is realized. In the long time limit, the dynamics arrives at a stationary state and the effects recede. Understanding temporal characteristics of directional energy flow will aid in designing microscopic energy transfer devices. PMID:26478230

  6. Light induces a rapid and transient increase in inositol-trisphosphate in toad rod outer segments

    SciTech Connect

    Brown, J.E.; Blazynski, C.; Cohen, A.I.

    1987-08-14

    The sub-second time course of changes in the content of (/sup 3/H)inositol-1,4,5-trisphosphate was determined in rod outer segments from very rapidly frozen Bufo retinas that had been incubated with (/sup 3/H)inositol. Rod outer segments were cut off frozen specimens with a cryostat microtome and the water soluble extracts were analyzed. The content of (/sup 3/H)inositol-1,4,5-trisphosphate rose after approximately 250 msec of bright illumination, but returned to the unstimulated level after 1 sec, whether the stimulus remained on or not. That is, there was rapid but transient change in the content of (/sup 3/H)inositol-1,4,5-trisphosphate after the onset of stimulation.

  7. Sustained and transient modulation of performance induced by emotional picture viewing

    PubMed Central

    Pereira, Mirtes Garcia; Volchan, Eliane; de Souza, Gabriela Guerra Leal; de Oliveira, Leticia; Campagnoli, Rafaela; Pinheiro, Walter Machado; Pessoa, Luiz

    2008-01-01

    We investigated how viewing task-irrelevant emotional pictures affects the performance of a subsequent non-emotional visual detection task. Subjects performed target-detection trials following the offset of individual unpleasant, pleasant and neutral pictures. Sustained interference occurred when subjects viewed blocked unpleasant pictures (mutilated bodies). Such slowing down of reaction time appeared to “build up” with time, consistent with the instatement of a defensive emotional state. With a randomized picture presentation, only a transient interference effect was observed, consistent with increased attentional demands during the processing of unpleasant pictures. During blocked presentation of affiliative pleasant pictures, reaction times were faster, suggesting the activation of appetitive motivational systems. Ultimately, both attentional and motivational systems are intricately tied in the brain and, together, determine behavior. PMID:17144753

  8. CSR induced microbunching gain estimation including transient effects in transport and recirculation arcs

    SciTech Connect

    Tsai, Cheng; Douglas, David R.; Li, Rui

    2015-09-01

    The coherent synchrotron radiation (CSR) of a high brightness electron beam traversing a series of dipoles, such as transport or recirculation arcs, may result in the microbunching instability (μBI). To accurately quantify the direct consequence of this effect, we further extend our previously developed semi-analytical Vlasov solver to include more relevant coherent radiation models than the steady-state free-space CSR impedance, such as the entrance and exit transient effects derived from upstream beam entering to and exiting from individual dipoles. The resultant microbunching gain functions and spectra for our example lattices are presented and compared with particle tracking simulation. Some underlying physics with inclusion of these effects are also discussed.

  9. Mapping Transient Hyperventilation Induced Alterations with Estimates of the Multi-Scale Dynamics of BOLD Signal

    PubMed Central

    Kiviniemi, Vesa; Remes, Jukka; Starck, Tuomo; Nikkinen, Juha; Haapea, Marianne; Silven, Olli; Tervonen, Osmo

    2009-01-01

    Temporal blood oxygen level dependent (BOLD) contrast signals in functional MRI during rest may be characterized by power spectral distribution (PSD) trends of the form 1/fα. Trends with 1/f characteristics comprise fractal properties with repeating oscillation patterns in multiple time scales. Estimates of the fractal properties enable the quantification of phenomena that may otherwise be difficult to measure, such as transient, non-linear changes. In this study it was hypothesized that the fractal metrics of 1/f BOLD signal trends can map changes related to dynamic, multi-scale alterations in cerebral blood flow (CBF) after a transient hyperventilation challenge. Twenty-three normal adults were imaged in a resting-state before and after hyperventilation. Different variables (1/f trend constant α, fractal dimension Df, and, Hurst exponent H) characterizing the trends were measured from BOLD signals. The results show that fractal metrics of the BOLD signal follow the fractional Gaussian noise model, even during the dynamic CBF change that follows hyperventilation. The most dominant effect on the fractal metrics was detected in grey matter, in line with previous hyperventilation vaso-reactivity studies. The α was able to differentiate also blood vessels from grey matter changes. Df was most sensitive to grey matter. H correlated with default mode network areas before hyperventilation but this pattern vanished after hyperventilation due to a global increase in H. In the future, resting-state fMRI combined with fractal metrics of the BOLD signal may be used for analyzing multi-scale alterations of cerebral blood flow. PMID:19636388

  10. Optical coherence tomography for visualizing transient strains and measuring large deformations in laser-induced tissue reshaping

    NASA Astrophysics Data System (ADS)

    Zaitsev, Vladimir Y.; Matveyev, Alexander L.; Matveev, Lev A.; Gelikonov, Grigory V.; Omelchenko, Alexander I.; Shabanov, Dmitry V.; Baum, Olga I.; Svistushkin, Valery M.; Sobol, Emil N.

    2016-11-01

    In the context of the development of emerging laser-assisted thermo-mechanical technologies for non-destructive reshaping of avascular collagenous tissues (cartilages and cornea), we report the first application of phase-sensitive optical coherence tomography (OCT) for visualizing transient strains involving supra-wavelength inter-frame displacements of scatterers. Usually phase-sensitive OCT assumes the visualization of sub-pixel and even sub-wavelength displacements of scatterers and fairly small strains (say, <10-3), which conventionally implies the necessity of averaging for enhancing the effective signal-to-noise ratio and, correspondingly, the application of small-amplitude actuators producing periodic deformations. The original approach used here allows for direct estimation of elevated strains ~10-2 (close to onset of intense speckle blinking) obviating the necessity of averaging and phase unwrapping for supra-wavelength inter-frame displacements. We demonstrate the possibility of mapping aperiodic thermally-induced transient strains with resultant large deformations on order of tens per cent. Such strains are typical in laser tissue reshaping, but are far beyond the range of conventionally discussed OCT-based strain mapping.

  11. Thapsigargin induces rapid, transient growth inhibition and c-fos expression followed by sustained growth stimulation in mouse keratinocyte cultures.

    PubMed

    Harmon, C S; Ducote, J; Xiong, Y

    1996-08-01

    Although the sesquiterpene lactone thapsigargin has been shown to possess hyperplastic and tumor-promoting activities when applied topically to mouse skin in vivo, the cellular mechanism(s) which underlie these effects are unclear. We show here that thapsigargin treatment of Primary mouse epidermal keratinocytes increased intracellular free Ca2+ concentration (Cai) in a concentration-dependent manner. Thapsigargin induced a rapid, transient elevation in keratinocyte Cai, in part due to the release of Ca2+ from intracellular stores. This response was followed by a sustained elevation in Ca2+, resulting entirely from calcium influx. Thapsigargin elicited a biphasic effect on keratinocyte DNA synthesis: a rapid inhibitory effect (50-60% inhibition at 4-8 h), followed by a very marked and sustained elevation. Prolonged treatment of keratinocytes with thapsigargin at relatively high concentrations resulted in cytotoxicity (inhibition of neutral red uptake). The rapid antiproliferative effect of thapsigargin was not associated with cytotoxicity, as determined by either neutral red uptake or by trypan blue exclusion, and was not blocked by pretreatment with Ro 31-7349, a selective inhibitor of protein kinase C. The rapid antiproliferative effect of thapsigargin was associated with rapid, transient activation of keratinocyte c-fos expression and rapid inhibition of total protein synthesis. Taken together, these findings raise the possibility that the hyperplastic and tumor-promoting activities of thapsigargin on epidermis in vivo result from direct keratinocyte growth stimulation as a consequence of a prolonged elevation in levels of Cai.

  12. Ginkgo biloba Prevents Transient Global Ischemia-Induced Delayed Hippocampal Neuronal Death Through Antioxidant and Anti-inflammatory Mechanism

    PubMed Central

    Tulsulkar, Jatin; Shah, Zahoor A.

    2012-01-01

    We have previously reported neuroprotective properties of Ginkgo biloba/EGb 761® (EGb 761) in transient and permanent mouse models of brain ischemia. In a quest to extend our studies on EGB 761 and its constituents further, we used a model of transient global ischemia induced delayed hippocampal neuronal death and inflammation. Mice pretreated with different test drugs for 7 days were subjected to eight-minute bilateral common carotid artery occlusion (tBCCAO) at day 8. After 7 days of reperfusion, mice brains were dissected out for TUNEL assay and immunohistochemistry. In-situ detection of fragmented DNA (TUNEL staining) showed that out of all test drugs, only EGb 761 (13.6% ± 3.2) pretreatment protected neurons in the hippocampus against global ischemia (vs. vehicle, 85.1% ± 9.9; p < 0.05). Immunofluorescence-based studies demonstrated that pretreatment with EGb 761 upregulated the expression levels of heme oxygenase 1 (HO1), nuclear factor erythroid 2-related factor 2 (Nrf2), and vascular endothelial growth factor (VEGF) as compared to the vehicle group. In addition, increased number of activated astrocytes and microglia in the vehicle group was observed to be significantly lower in the EGb 761 pretreated group. Together, these results suggest that EGb 761 is a multifunctional neuroprotective agent, and the protection is in part associated with activation of the HO1/Nrf2 pathway, upregulation of VEGF and downregulation of inflammatory mediators such as astrocytes and microglia. PMID:23228346

  13. A single, mild, transient scrotal heat stress causes hypoxia and oxidative stress in mouse testes, which induces germ cell death.

    PubMed

    Paul, Catriona; Teng, Serena; Saunders, Philippa T K

    2009-05-01

    Spermatogenesis is a temperature-dependent process, and increases in scrotal temperature can disrupt its progression. We previously showed that heat stress causes DNA damage in germ cells, an increase in germ cell death (as seen on TUNEL staining), and subfertility. The present study evaluated the stress response in mouse testes following a single mild transient scrotal heat exposure (40 degrees C or 42 degrees C for 30 min). We investigated markers of three types of stress response, namely, hypoxia, oxidative stress, and apoptosis. Heat stress caused an increase in expression of hypoxia-inducible factor 1 alpha (Hif1a) mRNA expression and translocation of HIF1A protein to the germ cell nucleus, consistent with hypoxic stress. Increased expression of heme oxygenase 1 (Hmox1) and the antioxidant enzymes glutathione peroxidase 1 (GPX1) and glutathione S-transferase alpha (GSTA) was consistent with a robust oxidative stress response. Germ cell death was associated with an increase in expression of the effector caspase cleaved caspase 3 and a decrease in expression of the protein inhibitor of caspase-activated DNase (ICAD). Reduced expression of ICAD contributes to increased activity of caspase-activated DNase and is consistent with the increased rates of DNA fragmentation that have been detected previously using TUNEL staining. These studies confirmed that transient mild testicular hyperthermia results in temperature-dependent germ cell death and demonstrated that elevated temperature results in a complex stress response, including induction of genes associated with oxidative stress and hypoxia.

  14. Transient development of Zeeman electromagnetically induced transparency during propagation of Raman-Ramsey pulses through Rb buffer gas cell

    NASA Astrophysics Data System (ADS)

    Nikolić, S. N.; Radonjić, M.; Lučić, N. M.; Krmpot, A. J.; Jelenković, B. M.

    2015-02-01

    We investigate, experimentally and theoretically, time development of Zeeman electromagnetically induced transparency (EIT) during propagation of two time separated polarization laser pulses, preparatory and probe, through Rb vapour. The pulses were produced by modifying laser intensity and degree of elliptical polarization. The frequency of the single laser beam is locked to the hyperfine {{F}g}=2\\to {{F}e}=1 transition of the D1 line in 87Rb. Transients in the intensity of {{σ }-} component of the transmitted light are measured or calculated at different values of the external magnetic field, during both preparatory and probe pulse. Zeeman EIT resonances at particular time instants of the pulse propagation are reconstructed by appropriate sampling of the transients. We observe how laser intensity, Ramsey sequence and the Rb cell temperature affect the time dependence of EIT line shapes, amplitudes and linewidths. We show that at early times of the probe pulse propagation, several Ramsey fringes are present in EIT resonances, while at later moments a single narrow peak prevails. Time development of EIT amplitudes are determined by the transmitted intensity of the {{σ }-} component during the pulse propagation.

  15. Precisely Molded Nanoparticle Displaying DENV-E Proteins Induces Robust Serotype-Specific Neutralizing Antibody Responses

    PubMed Central

    Hoekstra, Gabriel; Yi, Xianwen; Stone, Michelle; Horvath, Katie; Miley, Michael J.; DeSimone, Joseph; Luft, Chris J.; de Silva, Aravinda M.

    2016-01-01

    Dengue virus (DENV) is the causative agent of dengue fever and dengue hemorrhagic fever. The virus is endemic in over 120 countries, causing over 350 million infections per year. Dengue vaccine development is challenging because of the need to induce simultaneous protection against four antigenically distinct DENV serotypes and evidence that, under some conditions, vaccination can enhance disease due to specific immunity to the virus. While several live-attenuated tetravalent dengue virus vaccines display partial efficacy, it has been challenging to induce balanced protective immunity to all 4 serotypes. Instead of using whole-virus formulations, we are exploring the potentials for a particulate subunit vaccine, based on DENV E-protein displayed on nanoparticles that have been precisely molded using Particle Replication in Non-wetting Template (PRINT) technology. Here we describe immunization studies with a DENV2-nanoparticle vaccine candidate. The ectodomain of DENV2-E protein was expressed as a secreted recombinant protein (sRecE), purified and adsorbed to poly (lactic-co-glycolic acid) (PLGA) nanoparticles of different sizes and shape. We show that PRINT nanoparticle adsorbed sRecE without any adjuvant induces higher IgG titers and a more potent DENV2-specific neutralizing antibody response compared to the soluble sRecE protein alone. Antigen trafficking indicate that PRINT nanoparticle display of sRecE prolongs the bio-availability of the antigen in the draining lymph nodes by creating an antigen depot. Our results demonstrate that PRINT nanoparticles are a promising platform for delivering subunit vaccines against flaviviruses such as dengue and Zika. PMID:27764114

  16. Noggin inhibits hypoxia-induced proliferation by targeting store-operated calcium entry and transient receptor potential cation channels

    PubMed Central

    Yang, Kai; Lu, Wenju; Jia, Jing; Zhang, Jie; Zhao, Mingming; Wang, Sabrina; Jiang, Haiyang; Xu, Lei

    2015-01-01

    Abnormally elevated bone morphogenetic protein 4 (BMP4) expression and mediated signaling play a critical role in the pathogenesis of chronic hypoxia-induced pulmonary hypertension (CHPH). In this study, we investigated the expression level and functional significance of four reported naturally occurring BMP4 antagonists, noggin, follistatin, gremlin1, and matrix gla protein (MGP), in the lung and distal pulmonary arterial smooth muscle cell (PASMC). A 21-day chronic hypoxic (10% O2) exposure rat model was utilized, which has been previously shown to successfully establish experimental CHPH. Among the four antagonists, noggin, but not the other three, was selectively downregulated by hypoxic exposure in both the lung tissue and PASMC, in correlation with markedly elevated BMP4 expression, suggesting that the loss of noggin might account for the hypoxia-triggered BMP4 signaling transduction. Then, by using treatment of extrogenous recombinant noggin protein, we further found that noggin significantly normalized 1) BMP4-induced phosphorylation of cellular p38 and ERK1/2; 2) BMP4-induced phosphorylation of cellular JAK2 and STAT3; 3) hypoxia-induced PASMC proliferation; 4) hypoxia-induced store-operated calcium entry (SOCE), and 5) hypoxia-increased expression of transient receptor potential cation channels (TRPC1 and TRPC6) in PASMC. In combination, these data strongly indicated that the hypoxia-suppressed noggin accounts, at least partially, for hypoxia-induced excessive PASMC proliferation, while restoration of noggin may be an effective way to inhibit cell proliferation by suppressing SOCE and TRPC expression. PMID:25740156

  17. Toluene diisocyanate exposure induces airway inflammation of bronchial epithelial cells via the activation of transient receptor potential melastatin 8

    PubMed Central

    Kim, Joo-Hee; Jang, Young-Sook; Jang, Seung-Hun; Jung, Ki-Suck; Kim, Seung-Hyun; Ye, Young-Min; Park, Hae-Sim

    2017-01-01

    Toluene diisocyanate (TDI) is the most important cause of occupational asthma (OA), and various pathogenic mechanisms have been suggested. Of these mechanisms, neurogenic inflammation is an important inducer of airway inflammation. Transient receptor potential melastatin 8 (TRPM8) is a well-established cold-sensing cation channel that is expressed in both neuronal cells and bronchial epithelial cells. A recent genome-wide association study of TDI-exposed workers found a significant association between the phenotype of TDI-induced OA and the single-nucleotide polymorphism rs10803666, which has been mapped to the TRPM8 gene. We hypothesized that TRPM8 located in airway epithelial cells may be involved in the pathogenic mechanisms of TDI-induced OA and investigated its role. Bronchial epithelial cells were treated with TDI in a dose- and time-dependent manner. The expression levels of TRPM8 mRNA and protein were determined by quantitative real-time polymerase chain reaction and western blotting. TDI-induced morphological changes in the cells were evaluated by immunocytochemistry. Alterations in the transcripts of inflammatory cytokines were examined in accordance with TRPM8 activation by TDI. TRPM8 expression at both the mRNA and protein levels was enhanced by TDI in airway epithelial cells. TRPM8 activation by TDI led to significant increases in the mRNA of interleukin (IL)-4, IL-13, IL-25 and IL-33. The increased expression of the cytokine genes by TDI was partly attenuated after treatment with a TRPM8 antagonist. TDI exposure induces increased expression of TRPM8 mRNA in airway epithelial cells coupled with enhanced expression of inflammatory cytokines, suggesting a novel role of TRPM8 in the pathogenesis of TDI-induced OA. PMID:28255167

  18. The transient receptor potential ankyrin-1 mediates mechanical hyperalgesia induced by the activation of B1 receptor in mice.

    PubMed

    Meotti, Flavia Carla; Figueiredo, Cláudia Pinto; Manjavachi, Marianne; Calixto, João B

    2017-02-01

    The kinin receptor B1 and the transient receptor potential ankyrin 1 (TRPA1) work as initiators and gatekeepers of nociception and inflammation. This study reports that the nociceptive transmission induced by activation of B1 receptor is dependent on TRPA1 ion channel. The mechanical hyperalgesia was induced by intrathecal (i.t.) injection of B1 agonist des-Arginine(9)-bradykinin (DABK) or TRPA1 agonist cinnamaldehyde and was evaluated by the withdrawal response after von Frey Hair application in the hind paw. After behavioral experiments, lumbar spinal cord and dorsal root ganglia (DRG) were harvested to assess protein expression and mRNA by immunohistochemistry and real time-PCR, respectively. The pharmacological antagonism (HC030031) or the down-regulation of TRPA1 greatly inhibited the mechanical hyperalgesia induced by DABK. Intrathecal injection of DABK up regulated the ionized calcium binding adaptor molecule (Iba-1) in lumbar spinal cord (L5-L6); TRPA1 protein and mRNA in lumbar spinal cord; and B1 receptor mRNA in both lumbar spinal cord and DRG. The knockdown of TRPA1 prevented microglia activation induced by DABK. Furthermore, the mechanical hyperalgesia induced by either DABK or by cinnamaldehyde was significantly reduced by inhibition of cyclooxygenase (COX), protein kinase C (PKC) or phospholipase C (PLC). In summary, this study revealed that TRPA1 positively modulates the mechanical hyperalgesia induced by B1 receptor activation in the spinal cord and that the classical GPCR downstream molecules PLC, diacylglycerol (DAG), 3,4,5-inositide phosphate (IP3) and PKC are involved in the nociceptive transmission triggered by these two receptors.

  19. Fluorescence ratiometric properties induced by nanoparticle plasmonics and nanoscale dye dynamics.

    PubMed

    Hakonen, Aron

    2013-01-01

    Nanoscale transport of merocyanine 540 within/near the plasmon field of gold nanoparticles was recognized as an effective inducer of single-excitation dual-emission ratiometric properties. With a high concentration of the signal transducer (ammonium), a 700% increase in fluorescence was observed at the new red-shifted emission maximum, compared to a nanoparticle free sensor membrane. A previously nonrecognized isosbestic point is demonstrated at 581.4 ± 0.1 nm. The mechanism can be utilized for enhanced and simplified ratiometric optical chemical sensors and potentially for thin film engineering to make solar cells more effective and stable by a broader and more regulated absorption.

  20. Effect of fullerenol surface chemistry on nanoparticle binding-induced protein misfolding

    NASA Astrophysics Data System (ADS)

    Radic, Slaven; Nedumpully-Govindan, Praveen; Chen, Ran; Salonen, Emppu; Brown, Jared M.; Ke, Pu Chun; Ding, Feng

    2014-06-01

    Fullerene and its derivatives with different surface chemistry have great potential in biomedical applications. Accordingly, it is important to delineate the impact of these carbon-based nanoparticles on protein structure, dynamics, and subsequently function. Here, we focused on the effect of hydroxylation -- a common strategy for solubilizing and functionalizing fullerene -- on protein-nanoparticle interactions using a model protein, ubiquitin. We applied a set of complementary computational modeling methods, including docking and molecular dynamics simulations with both explicit and implicit solvent, to illustrate the impact of hydroxylated fullerenes on the structure and dynamics of ubiquitin. We found that all derivatives bound to the model protein. Specifically, the more hydrophilic nanoparticles with a higher number of hydroxyl groups bound to the surface of the protein via hydrogen bonds, which stabilized the protein without inducing large conformational changes in the protein structure. In contrast, fullerene derivatives with a smaller number of hydroxyl groups buried their hydrophobic surface inside the protein, thereby causing protein denaturation. Overall, our results revealed a distinct role of surface chemistry on nanoparticle-protein binding and binding-induced protein misfolding.Fullerene and its derivatives with different surface chemistry have great potential in biomedical applications. Accordingly, it is important to delineate the impact of these carbon-based nanoparticles on protein structure, dynamics, and subsequently function. Here, we focused on the effect of hydroxylation -- a common strategy for solubilizing and functionalizing fullerene -- on protein-nanoparticle interactions using a model protein, ubiquitin. We applied a set of complementary computational modeling methods, including docking and molecular dynamics simulations with both explicit and implicit solvent, to illustrate the impact of hydroxylated fullerenes on the structure and

  1. Transient bond scission of polytetrafluoroethylene under laser-induced shock compression studied by nanosecond time-resolved Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazutaka; Wakabayashi, Kunihiko; Konodo, Ken-Ichi

    2001-06-01

    Nanosecond time-resolved Raman spectroscopy has been performed to study polymer films, polytetrafluoroethylene (PTFE), under laser driven shock compression at laser power density of 4.0 GW/cm^2. The overtone-mode line of PTFE showed red shift (18 cm-1) at delay time of 9.3 ns due to the shock compression and corresponding pressure was estimated to be approximately 2.7 GPa by analyzing static and shock compression data. The estimated pressure was in good agreement with that estimated by ablation pressure in glass-confined geometry. A new vibrational line at 1900 cm-1 appeared only under shock compression and was assigned to the C=C streching in transient species such as a monomer (C_2F_4) produced by the shock-induced bond scission. Intensity of the new line increased with increasing delay time along propagation of the shock compression with a shock velocity of 2.5 km/s.

  2. Fano resonance-induced negative optical scattering force on plasmonic nanoparticles.

    PubMed

    Chen, Huajin; Liu, Shiyang; Zi, Jian; Lin, Zhifang

    2015-02-24

    We demonstrate theoretically that Fano resonance can induce a negative optical scattering force acting on plasmonic nanoparticles in the visible light spectrum when an appropriate manipulating laser beam is adopted. Under the illumination of a zeroth-order Bessel beam, the plasmonic nanoparticle at its Fano resonance exhibits a much stronger forward scattering than backward scattering and consequently leads to a net longitudinal backward optical scattering force, termed Fano resonance-induced negative optical scattering force. The extinction spectra obtained based on the Mie theory show that the Fano resonance arises from the interference of simultaneously excited multipoles, which can be either a broad electric dipole mode and a narrow electric quadrupole mode, or a quadrupole and an octupole mode mediated by the broad electric dipole. Such Fano resonance-induced negative optical scattering force is demonstrated to occur for core-shell, homogeneous, and hollow metallic particles and can therefore be expected to be universal for many other nanostructures exhibiting Fano resonance, adding considerably to the flexibility of optical micromanipulation on the plasmonic nanoparticles. More interestingly, the flexible tunability of the Fano resonance by particle morphology opens up the possibility of tailoring the optical scattering force accordingly, offering an additional degree of freedom to optical selection and sorting of plasmonic nanoparticles.

  3. TPGS-Stabilized Curcumin Nanoparticles Exhibit Superior Effect on Carrageenan-Induced Inflammation in Wistar Rat

    PubMed Central

    Rachmawati, Heni; Safitri, Dewi; Pradana, Aditya Trias; Adnyana, I Ketut

    2016-01-01

    Curcumin, a hydrophobic polyphenol compound derived from the rhizome of the Curcuma genus, has a wide spectrum of biological and pharmacological applications. Previously, curcumin nanoparticles with different stabilizers had been produced successfully in order to enhance solubility and per oral absorption. In the present study, we tested the anti-inflammatory effect of d-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS)-stabilized curcumin nanoparticles in vivo. Lambda-carrageenan (λ-carrageenan) was used to induce inflammation in rats; it was given by an intraplantar route and intrapelurally through surgery in the pleurisy test. In the λ-carrageenan-induced edema model, TPGS-stabilized curcumin nanoparticles were given orally one hour before induction and at 0.5, 4.5, and 8.5 h after induction with two different doses (1.8 and 0.9 mg/kg body weight (BW)). Sodium diclofenac with a dose of 4.5 mg/kg BW was used as a standard drug. A physical mixture of curcumin-TPGS was also used as a comparison with a higher dose of 60 mg/kg BW. The anti-inflammatory effect was assessed on the edema in the carrageenan-induced paw edema model and by the volume of exudate as well as the number of leukocytes reduced in the pleurisy test. TPGS-stabilized curcumin nanoparticles with lower doses showed better anti-inflammatory effects, indicating the greater absorption capability through the gastrointestinal tract. PMID:27537907

  4. Nanoparticle induced conformational change in DNA and chirality of silver nanoclusters.

    PubMed

    Roy, Sarita; Basak, Soumen; Dasgupta, Anjan Kr

    2010-02-01

    Nano-clusters formed on macromolecular templates carry the symmetry information of the template. Templates with broken symmetry thus lead to formation of asymmetric clusters. In response, such clusters induce a compensatory stress on the embedded template. Silver nanoparticles grown on a covalently closed negatively supercoiled plasmid DNA (pUC19) exhibit chiral behavior and as a reciprocal response, one observes alteration in DNA conformation. The inference was drawn using gel mobility-shift studies in which a silver nanoparticle (but not ions) induces a mobility shift implying a drift from supercoiled to relaxed state of the plasmid. Supporting evidences for such structural alterations were obtained from circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR). Silver ion and silver nanoparticles induce differential FT-IR signals reflected in the fingerprint regions 1720, 1666, 1611, 1529 cm(-1) that respectively corresponds to binding in GT, ATGC, C, and AC (A, T, G, and C representing the four nucleotides). Existence of CD signal in the silver plasmon region (350-550 nm) suggests formation of a chiral clustering of nanoparticles. The reciprocal effect on the covalently closed circular (CCC) pUC19 DNA, namely the transition to a relaxed state, can be regarded as a mimicry of the topological enzyme acting on such CCC DNA.

  5. Stress response induced by carbon nanoparticles in Paracentrotus lividus

    PubMed Central

    Carata, Elisabetta; Anna Tenuzzo, Bernardetta; Arnò, Federica; Buccolieri, Alessandro; Serra, Antonio; Manno, Daniela; Dini, Luciana

    2012-01-01

    Members of the 14-3-3 protein family are involved in many important cellular events, including stress response, survival and apoptosis. Genes of the 14-3-3 family are conserved from plants to humans, and some members are responsive to UV radiation. Despite the high rate of pollution generated by nano-pollutants, up to now their toxic effect on development is totally obscure. Embryos treated with carbon nanoparticles, RNA preparation, retro-transcription and quantitative real-time PCR. In response to carbon nano-particles exposure, the embryos collected 24 h later showed a 3,07-fold at 5x1012 p and a 1,58-fold at 2.5x1013 p and a 1,92-fold at 2.5x1014 p increase in Pl14-3-3ε transcript levels compared with controls. The Pl14-3-3ε mRNA delocalization parallels the failure in archenteron elongation observed morphologically, as well as the lack of specific endoderm markers. Here, we report the isolation of the complete cDNA encoding the 14-3-3 epsilon isoform from Paracentrotus lividus sea urchin embryos, referred to as Pl14-3-3ε. Pl14-3-3ε mRNA levels were measured by RT-PCR during development and found to increase from the mesenchyme blastula to the prism stage. Our results confirm the involvement of 14-3-3ε in the stress response elicited by carbon nano-particles. PMID:24551756

  6. Stress response induced by carbon nanoparticles in Paracentrotus lividus.

    PubMed

    Carata, Elisabetta; Anna Tenuzzo, Bernardetta; Arnò, Federica; Buccolieri, Alessandro; Serra, Antonio; Manno, Daniela; Dini, Luciana

    2012-01-01

    Members of the 14-3-3 protein family are involved in many important cellular events, including stress response, survival and apoptosis. Genes of the 14-3-3 family are conserved from plants to humans, and some members are responsive to UV radiation. Despite the high rate of pollution generated by nano-pollutants, up to now their toxic effect on development is totally obscure. Embryos treated with carbon nanoparticles, RNA preparation, retro-transcription and quantitative real-time PCR. In response to carbon nano-particles exposure, the embryos collected 24 h later showed a 3,07-fold at 5x10(12) p and a 1,58-fold at 2.5x10(13) p and a 1,92-fold at 2.5x10(14) p increase in Pl14-3-3ε transcript levels compared with controls. The Pl14-3-3ε mRNA delocalization parallels the failure in archenteron elongation observed morphologically, as well as the lack of specific endoderm markers. Here, we report the isolation of the complete cDNA encoding the 14-3-3 epsilon isoform from Paracentrotus lividus sea urchin embryos, referred to as Pl14-3-3ε. Pl14-3-3ε mRNA levels were measured by RT-PCR during development and found to increase from the mesenchyme blastula to the prism stage. Our results confirm the involvement of 14-3-3ε in the stress response elicited by carbon nano-particles.

  7. Metal nanoparticle fluids with magnetically induced electrical switching properties

    NASA Astrophysics Data System (ADS)

    Kim, Younghoon; Cho, Jinhan

    2013-05-01

    We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media.We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00653k

  8. Immobilization Stress With α2-Adrenergic Stimulation Induces Regional and Transient Reduction of Cardiac Contraction Through Gi Coupling in Rats.

    PubMed

    Kuroda, Ryohei; Shintani-Ishida, Kaori; Unuma, Kana; Yoshida, Ken-ichi

    2015-01-01

    Stress cardiomyopathy is characterized by transient apical hypokinesia related to catecholamine overflow. Recently, excessive epinephrine administration was shown to recapitulate stress cardiomyopathy through β2-adrenoceptor (AR)-inhibitory G protein (Gi) coupling in rats. We aimed to study whether α2-AR and Gi affect cardiac contraction in rats in which emotional stress was evoked using immobilization (IMO). Echocardiography results showed that when male rats were exposed to IMO for 30 minutes and then injected with the α2-AR agonist xylazine (Xy), ejection fraction and the movement of the anterior wall (AW) were suppressed, maximally at 5 minutes post-injection, whereas posterior wall (PW) movement was preserved. At the same time points, the phosphorylation of Ser282 in myosin-binding protein-C (MyBP-C-Ser282) was higher in the PW than in the AW. Pretreatment with the Gi inhibitor pertussis toxin (PTX) reversed the low contractility and MyBP-C-Ser282 phosphorylation in the AW, but induced lethal heart failure in 3 out of 11 rats. Moreover, at 5 minutes after Xy injection following 30 minutes of IMO, serum epinephrine levels were increased. Thus, in rats exposed to psychological stress, α2-AR stimulation triggered transient hypo-contractility and MyBP-C-Ser282 hypo-phosphorylation in the AW, in association with an epinephrine surge. PTX treatment reversed the AW hypo-contractility and MyBP-C hypo-phosphorylation, but induced acute heart failure. These findings suggest α2AR/Gi-dependent signaling attenuates MyBP-C phosphorylation and contractility in the AW through an epinephrine surge in rats subjected to IMO and α2-AR stimulation. This model can recapitulate stress cardiomyopathy and thereby deepen our understanding of regional cardiac hypo-contractility and prosurvival mechanisms.

  9. Bcl-xL-inhibitory BH3 mimetics can induce a transient thrombocytopathy that undermines the hemostatic function of platelets.

    PubMed

    Schoenwaelder, Simone M; Jarman, Kate E; Gardiner, Elizabeth E; Hua, My; Qiao, Jianlin; White, Michael J; Josefsson, Emma C; Alwis, Imala; Ono, Akiko; Willcox, Abbey; Andrews, Robert K; Mason, Kylie D; Salem, Hatem H; Huang, David C S; Kile, Benjamin T; Roberts, Andrew W; Jackson, Shaun P

    2011-08-11

    BH3 mimetics are a new class of proapo-ptotic anticancer agents that have shown considerable promise in preclinical animal models and early-stage human trials. These agents act by inhibiting the pro-survival function of one or more Bcl-2-related proteins. Agents that inhibit Bcl-x(L) induce rapid platelet death that leads to thrombocytopenia; however, their impact on the function of residual circulating platelets remains unclear. In this study, we demonstrate that the BH3 mimetics, ABT-737 or ABT-263, induce a time- and dose-dependent decrease in platelet adhesive function that correlates with ectodomain shedding of the major platelet adhesion receptors, glycoprotein Ibα and glycoprotein VI, and functional down-regulation of integrin α(IIb)β(3). Analysis of platelets from mice treated with higher doses of BH3 mimetics revealed the presence of a subpopulation of circulating platelets undergoing cell death that have impaired activation responses to soluble agonists. Functional analysis of platelets by intravital microscopy revealed a time-dependent defect in platelet aggregation at sites of vascular injury that correlated with an increase in tail bleeding time. Overall, these studies demonstrate that Bcl-x(L)-inhibitory BH3 mimetics not only induce thrombocytopenia but also a transient thrombocytopathy that can undermine the hemostatic function of platelets.

  10. Transient antibody targeting of CD45RC induces transplant tolerance and potent antigen-specific regulatory T cells

    PubMed Central

    Picarda, Elodie; Bézie, Séverine; Boucault, Laetitia; Autrusseau, Elodie; Kilens, Stéphanie; Martinet, Bernard; Daguin, Véronique; Donnart, Audrey; Charpentier, Eric; Anegon, Ignacio

    2017-01-01

    Rat and human CD4+ and CD8+ Tregs expressing low levels of CD45RC have strong immunoregulatory properties. We describe here that human CD45 isoforms are nonredundant and identify distinct subsets of cells. We show that CD45RC is not expressed by CD4+ and CD8+ Foxp3+ Tregs, while CD45RA/RB/RO are. Transient administration of a monoclonal antibody (mAb) targeting CD45RC in a rat cardiac allotransplantation model induced transplant tolerance associated with inhibition of allogeneic humoral responses but maintained primary and memory responses against cognate antigens. Anti-CD45RC mAb induced rapid death of CD45RChigh T cells through intrinsic cell signaling but preserved and potentiated CD4+ and CD8+ CD45RClow/– Tregs, which are able to adoptively transfer donor-specific tolerance to grafted recipients. Anti-CD45RC treatment results in distinct transcriptional signature of CD4+ and CD8+ CD45RClow/– Tregs. Finally, we demonstrate that anti-human CD45RC treatment inhibited graft-versus-host disease (GVHD) in immune-humanized NSG mice. Thus, short-term anti-CD45RC is a potent therapeutic candidate to induce transplantation tolerance in human. PMID:28194440

  11. Forsythoside A exerts antipyretic effect on yeast-induced pyrexia mice via inhibiting transient receptor potential vanilloid 1 function

    PubMed Central

    Liu, Cuiling; Su, Hongchang; Wan, Hongye; Qin, Qingxia; Wu, Xuan; Kong, Xiangying; Lin, Na

    2017-01-01

    Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel gated by noxious heat, playing major roles in thermoregulation. Forsythoside A (FT-A) is the most abundant phenylethanoid glycosides in Fructus Forsythiae, which has been prescribed as a medicinal herb for treating fever in China for a long history. However, how FT-A affects pyrexia and what is the underlying molecular mechanism remain largely unknown. Here we found that FT-A exerted apparent antipyretic effect through decreasing the levels of prostaglandin E2 (PGE2) and interleukin 8 (IL-8) in a dose-dependent fashion on the yeast induced pyrexia mice. Interestingly, FT-A significantly downregulated TRPV1 expression in the hypothalamus and dorsal root ganglion (DRG) of the yeast induced pyrexia mice. Moreover, FT-A inhibited IL-8 and PGE2 secretions, and calcium influx in the HEK 293T-TRPV1 cells after stimulated with capsaicin, the specific TRPV1 agonist. Further investigation of the molecular mechanisms revealed that FT-A treatment rapidly inhibited phosphorylation of extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38 in both yeast induced pyrexia mice and HEK 293T-TRPV1 cells. These results suggest that FT-A may serve as a potential antipyretic agent and the therapeutic action of Fructus Forsythiae on pyretic related disease is, in part, due to the FT-A activities. PMID:28123347

  12. Nafamostat mesilate attenuates transient focal ischemia/reperfusion-induced brain injury via the inhibition of endoplasmic reticulum stress.

    PubMed

    Kwon, Sun Kwan; Ahn, Moonsang; Song, Hee-Jung; Kang, Shin Kwang; Jung, Saet-Byel; Harsha, Nagar; Jee, Sungju; Moon, Jae Young; Suh, Kwang-Sun; Lee, Sang Do; Jeon, Byeong Hwa; Kim, Dong Woon; Kim, Cuk-Seong

    2015-11-19

    Nafamostat mesilate (NM), a serine protease inhibitor, has a broad range of clinical applications that include use as an anticoagulant during hemodialysis in cerebral hemorrhage patients, as a hemoperfusion anticoagulant for patients with intravascular coagulation, hemorrhagic lesions, and hemorrhagic tendencies, and for the improvement of acute pancreatitis. However, the effects of NM on acute cerebral ischemia have yet to be investigated. Thus, the present study utilized a rat model in which transient middle cerebral artery occlusion (MCAO) was used to induce ischemic injury to investigate the effects of NM on infarct volume and histological and biological changes. NM (1mg/kg) was intravenously administered prior to and after the MCAO procedure. Compared to control rats, the administration of NM significantly decreased infarct size and the extent of brain edema after the induction of focal ischemia via MCAO. Additionally, NM treatment attenuated MCAO-induced neuronal degeneration and activation of microglia and astrocytes. NM treatment also inhibited the MCAO-induced expression levels of glucose-regulated protein 78 (GRP78), CATT/EBP homologous protein (CHOP), and p-eukaryotic initiation factor 2α (eIF2α), which are endoplasmic reticulum (ER) stress markers, in the cerebral cortex. The present findings demonstrate that NM exerts neuroprotective effects in the brain following focal ischemia via, at least in part, the inhibition of ER stress.

  13. Chemotherapy induces transient sex chromosomal and autosomal aneuploidy in human sperm.

    PubMed

    Robbins, W A; Meistrich, M L; Moore, D; Hagemeister, F B; Weier, H U; Cassel, M J; Wilson, G; Eskenazi, B; Wyrobek, A J

    1997-05-01

    Each year more than 20,000 children and young persons of reproductive age are exposed to known mutagens in the form of chemo- and/or radiotherapy for cancer in the States. As more of these treatments are effective there is growing concern that genetic defects are introduced in the germ cells of these young patients. It is well documented for male rodents that treatment with chemo- and radio-therapeutic agents before mating can cause genetic damage in the germ line, and the magnitude of heritable effects depends on the spermatogenic cell stage treated. Similar germinal effects are suspected to occur in humans but remain unproven. Hodgkin's disease (HD) is an example of a malignancy which is typically diagnosed during a patient's reproductive years. In our study we observed eight male HD patients who were treated with NOVP (Novanthrone, Oncovin, Vinblastine, Prednisone) chemotherapy. We evaluated sperm aneuploidy using multi-colour fluorescence in situ hybridization (FISH), and found approximately 5-fold increases in sperm with disomies, diploidies and complex genotypes involving chromosome X, Y and 8. Increases in sex chromosome aneuploidies arose from segregation errors at meiosis I as well as meiosis II. The aneuploidy effects were transient, however, declining to pretreatment levels within approximately 100 days after the end of the therapy. When compared with normal men, some HD patients showed higher proportions of certain sperm aneuploidy types even before their first therapy.

  14. Changes in the Adriatic oceanographic properties induced by the Eastern Mediterranean Transient

    NASA Astrophysics Data System (ADS)

    Vilibić, I.; Matijević, S.; Šepić, J.

    2012-01-01

    Long-term time series of physical and chemical parameters collected between 1960 and 2010 along the Palagruža Sill transect, middle Adriatic Sea, have been investigated in terms of average water properties and their variability. Nutrients, especially orthophosphates, reached rather higher levels of concentration below the euphotic zone between 1991 and 1998, the highest in the investigated period. Simultaneously, the N:P ratio, which is normally larger than 25:1, decreased to values less than 16:1 in the euphotic zone, indicating a switch from typical phosphorus-limited to nitrogen-limited preconditioning of the primary production. Higher-than-usual nutrient levels, coupled with lower-than-usual temperature, salinity and dissolved oxygen, have been attributed to the intermediate inflow of the nutrient richer Western Mediterranean waters to the Adriatic, entering the Adriatic during the anticyclonic phase of the Bimodal Adriatic-Ionian Oscillation (BiOS). The BiOS and the Northern Ionian anticyclone have been uniquely strengthened by the Eastern Mediterranean Transient occurring in the early 1990s. The observed changes have a potential to impact the primary production and presumably the whole trophic chain in the Adriatic and were likely responsible for the observed fluctuation in abundances of various species and fish stock, indicating a high relevance of the observed physical processes.

  15. Meteor-induced transient sporadic E as inferred from rapid-run ionosonde observations at midlatitudes

    NASA Astrophysics Data System (ADS)

    Maruyama, Takashi; Kato, Hisao; Nakamura, Maho

    2008-09-01

    Observations were made with a rapid-run ionosonde during a 1-month period from the end of July to the end of August 2002 that included the Perseid meteor shower. Ionograms were obtained at 1-minute intervals. All the echo traces below a virtual height of 200 km were hand-scaled for detecting weak and broken traces as well as well-determined sporadic E. Among the scaled E-region traces, a distinct meteor echo persisting for 40 min was observed. This long-duration meteor event was similar to that observed during the Leonid meteor shower in 2001. However the apparent height of the echo traces in the current event first decreased and then increased after equaling the height of a persistent sporadic E layer, while the apparent height of the long-duration meteor echo trace observed in Leonids 2001 remained nearly constant. The descending rate of the meteor echo was approximately 22 m/s, which was considerably greater than that of the tidal ion layer trapped in a downward-moving wind shear node. We ascribe the long-duration meteor echo to a transient and horizontally drifting sporadic E patch generated from meteor trail plasma.

  16. Glucose restriction induces transient G2 cell cycle arrest extending cellular chronological lifespan

    PubMed Central

    Masuda, Fumie; Ishii, Mahiro; Mori, Ayaka; Uehara, Lisa; Yanagida, Mitsuhiro; Takeda, Kojiro; Saitoh, Shigeaki

    2016-01-01

    While glucose is the fundamental source of energy in most eukaryotes, it is not always abundantly available in natural environments, including within the human body. Eukaryotic cells are therefore thought to possess adaptive mechanisms to survive glucose-limited conditions, which remain unclear. Here, we report a novel mechanism regulating cell cycle progression in response to abrupt changes in extracellular glucose concentration. Upon reduction of glucose in the medium, wild-type fission yeast cells undergo transient arrest specifically at G2 phase. This cell cycle arrest is dependent on the Wee1 tyrosine kinase inhibiting the key cell cycle regulator, CDK1/Cdc2. Mutant cells lacking Wee1 are not arrested at G2 upon glucose limitation and lose viability faster than the wild-type cells under glucose-depleted quiescent conditions, suggesting that this cell cycle arrest is required for extension of chronological lifespan. Our findings indicate the presence of a novel cell cycle checkpoint monitoring glucose availability, which may be a good molecular target for cancer therapy. PMID:26804466

  17. Hepatoprotective effect of engineered silver nanoparticles coated bioactive compounds against diethylnitrosamine induced hepatocarcinogenesis in experimental mice.

    PubMed

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-02-01

    Nanoparticle based drug delivery can rapidly improves the therapeutic potential of anti-cancer agents. The present study focused to evaluate the hepatoprotective activity of silver nanoparticles (AgNPs) synthesized using aqueous extracts of Andrographis paniculata leaves (ApAgNPs) and Semecarpus anacardium nuts (SaAgNPs) against diethylnitrosamine (DEN) induced liver cancer in mice model. The physico-chemical properties of synthesized AgNPs were characterized by Fourier transform infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX) spectrum, Zeta potential and Dynamic Light Scattering (DLS) analysis. The surface plasmon resonance (SPR) absorption spectrum revealed a strong peak at 420nm for both SaAgNPs and ApAgNPs. FTIR results exhibited the presence of possible functional groups in the synthesized AgNPs. TEM analysis determined the hexagonal, and spherical shape of the synthesized silver nanoparticles. The XRD and SAED pattern confirmed the crystalline nature and crystalline size of the AgNPs. EDX result clearly showed strong silver signals in the range between 2 and 4keV. Zeta potential measurements indicated a sharp peak at -3.93 and -13.8mV for ApAgNPs and SaAgNPs, respectively. DLS measurement expressed the particle size distribution was 70 and 60nm for ApAgNPs and SaAgNPs, respectively. DEN (20mg/kg b.wt.) was subjected to induce liver cancer in mice for 8weeks and treated with biosynthesized silver nanoparticles. Interestingly, ApAgNPs and SaAgNPs treated DEN induced animal groups show a decreased level of aspartate amino transferase (AST), alanine amino transferase (ALT), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) activity and elevated level of catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) activity over untreated DEN control

  18. Single-electron induced surface plasmons on a topological nanoparticle

    PubMed Central

    Siroki, G.; Lee, D.K.K.; Haynes, P. D.; Giannini, V.

    2016-01-01

    It is rarely the case that a single electron affects the behaviour of several hundred thousands of atoms. Here we demonstrate a phenomenon where this happens. The key role is played by topological insulators—materials that have surface states protected by time-reversal symmetry. Such states are delocalized over the surface and are immune to its imperfections in contrast to ordinary insulators. For topological insulators, the effects of these surface states will be more strongly pronounced in the case of nanoparticles. Here we show that under the influence of light a single electron in a topologically protected surface state creates a surface charge density similar to a plasmon in a metallic nanoparticle. Such an electron can act as a screening layer, which suppresses absorption inside the particle. In addition, it can couple phonons and light, giving rise to a previously unreported topological particle polariton mode. These effects may be useful in the areas of plasmonics, cavity electrodynamics and quantum information. PMID:27491515

  19. Mitochondrial dysfunction in titanium dioxide nanoparticle-induced neurotoxicity.

    PubMed

    Nalika, Nandini; Parvez, Suhel

    2015-01-01

    Nanotechnology has emerged as a field of scientific innovation which has opened up a plethora of concerns for the potential impact on human and environment. Various toxicological studies have confirmed that nanoparticles (NPs) can be potentially hazardous because of their unique small size and physico-chemical properties. With the wide applications of titanium dioxide nanoparticles (TNPs) in day-to-day life in form of cosmetics, paints, sterilization and so on, there is growing concern regarding the deleterious effects of TNPs on central nervous system. Mitochondria is an important origin for generation of energy as well as free radicals and these free radicals can lead to mitochondrial damage and finally lead to apoptosis. The objective of our study was to elucidate the potential neurotoxic effect of TNPs in anatase form. Oxidative stress was determined by measuring lipid peroxidation and protein carbonyl content which was found to be significantly increased. Reduced glutathione content and major glutathione metabolizing enzymes were also modulated signifying the role of glutathione redox cycle in the pathophysiology of TNPs. Mitochondrial complexes were also modulated from the exposure to TNPs. The present study indicates that nanosize TNPs may pose a health risk to mitochondrial brain with the generation of reactive oxygen species, and thus NPs should be carefully used.

  20. Three-dimensional Cu microfabrication using femtosecond laser-induced reduction of CuO nanoparticles

    NASA Astrophysics Data System (ADS)

    Arakane, Shun; Mizoshiri, Mizue; Sakurai, Junpei; Hata, Seiichi

    2017-01-01

    Three-dimensional Cu microstructures were formed using a combined process of dispensing coating and femtosecond laser-induced reduction of CuO nanoparticles. Layer-by-layer lamination of two-dimensional Cu micropatterns was performed by alternately coating with a CuO nanoparticle solution and using direct laser writing, followed by the removal of nonirradiated CuO nanoparticles. The resistance of the 3D microstructures decreased as the number of layers increased, indicating that each layer was electrically connected to the others. We also demonstrated the fabrication of a microbridge heater composed of electrode pads and a microbridge, and found that its heating characteristics are suitable for use in microsensors, such as thermal-type flow sensors.

  1. Conformational Changes in High-Density Lipoprotein Nanoparticles Induced by High Payloads of Paramagnetic Lipids

    PubMed Central

    2016-01-01

    High-density lipoprotein (HDL) nanoparticles doped with gadolinium lipids can be used as magnetic resonance imaging diagnostic agents for atherosclerosis. In this study, HDL nanoparticles with different molar fractions of gadolinium lipids (0 < xGd-lipids < 0.33) were prepared, and the MR relaxivity values (r1 and r2) for all compositions were measured. Both r1 and r2 parameters reached a maximal value at a molar fraction of approximately xGd-lipids = 0.2. Higher payloads of gadolinium did not significantly increase relaxivity values but induced changes in the structure of HDL, increasing the size of the particles from dH = 8.2 ± 1.6 to 51.7 ± 7.3 nm. High payloads of gadolinium lipids trigger conformational changes in HDL, with potential effects on the in vivo behavior of the nanoparticles. PMID:27713933

  2. Ultrasmall nanoparticles induce ferroptosis in nutrient-deprived cancer cells and suppress tumour growth

    PubMed Central

    Kim, Sung Eun; Zhang, Li; Ma, Kai; Riegman, Michelle; Chen, Feng; Ingold, Irina; Conrad, Marcus; Turker, Melik Ziya; Gao, Minghui; Jiang, Xuejun; Monette, Sebastien; Pauliah, Mohan; Gonen, Mithat; Zanzonico, Pat; Quinn, Thomas; Wiesner, Ulrich; Bradbury, Michelle S.; Overholtzer, Michael

    2016-01-01

    The design of cancer-targeting particles with precisely-tuned physiocochemical properties may enhance delivery of therapeutics and access to pharmacological targets. However, molecular level understanding of the interactions driving the fate of nanomedicine in biological systems remains elusive. Here, we show that ultrasmall (< 10 nm in diameter) poly(ethylene glycol) (PEG)-coated silica nanoparticles, functionalized with melanoma-targeting peptides, can induce a form of programmed cell death known as ferroptosis in starved cancer cells and cancer-bearing mice. Tumor xenografts in mice intravenously injected with nanoparticles using a high-dose multiple injection scheme exhibit reduced growth or regression, in a manner that is reversed by the pharmacological inhibitor of ferroptosis, liproxstatin-1. These data demonstrate that ferroptosis can be targeted by ultrasmall silica nanoparticles and may have therapeutic potential. PMID:27668796

  3. Ultrasmall nanoparticles induce ferroptosis in nutrient-deprived cancer cells and suppress tumour growth.

    PubMed

    Kim, Sung Eun; Zhang, Li; Ma, Kai; Riegman, Michelle; Chen, Feng; Ingold, Irina; Conrad, Marcus; Turker, Melik Ziya; Gao, Minghui; Jiang, Xuejun; Monette, Sebastien; Pauliah, Mohan; Gonen, Mithat; Zanzonico, Pat; Quinn, Thomas; Wiesner, Ulrich; Bradbury, Michelle S; Overholtzer, Michael

    2016-11-01

    The design of cancer-targeting particles with precisely tuned physicochemical properties may enhance the delivery of therapeutics and access to pharmacological targets. However, a molecular-level understanding of the interactions driving the fate of nanomedicine in biological systems remains elusive. Here, we show that ultrasmall (<10 nm in diameter) poly(ethylene glycol)-coated silica nanoparticles, functionalized with melanoma-targeting peptides, can induce a form of programmed cell death known as ferroptosis in starved cancer cells and cancer-bearing mice. Tumour xenografts in mice intravenously injected with nanoparticles using a high-dose multiple injection scheme exhibit reduced growth or regression, in a manner that is reversed by the pharmacological inhibitor of ferroptosis, liproxstatin-1. These data demonstrate that ferroptosis can be targeted by ultrasmall silica nanoparticles and may have therapeutic potential.

  4. Ultrasmall nanoparticles induce ferroptosis in nutrient-deprived cancer cells and suppress tumour growth

    NASA Astrophysics Data System (ADS)

    Kim, Sung Eun; Zhang, Li; Ma, Kai; Riegman, Michelle; Chen, Feng; Ingold, Irina; Conrad, Marcus; Turker, Melik Ziya; Gao, Minghui; Jiang, Xuejun; Monette, Sebastien; Pauliah, Mohan; Gonen, Mithat; Zanzonico, Pat; Quinn, Thomas; Wiesner, Ulrich; Bradbury, Michelle S.; Overholtzer, Michael

    2016-11-01

    The design of cancer-targeting particles with precisely tuned physicochemical properties may enhance the delivery of therapeutics and access to pharmacological targets. However, a molecular-level understanding of the interactions driving the fate of nanomedicine in biological systems remains elusive. Here, we show that ultrasmall (<10 nm in diameter) poly(ethylene glycol)-coated silica nanoparticles, functionalized with melanoma-targeting peptides, can induce a form of programmed cell death known as ferroptosis in starved cancer cells and cancer-bearing mice. Tumour xenografts in mice intravenously injected with nanoparticles using a high-dose multiple injection scheme exhibit reduced growth or regression, in a manner that is reversed by the pharmacological inhibitor of ferroptosis, liproxstatin-1. These data demonstrate that ferroptosis can be targeted by ultrasmall silica nanoparticles and may have therapeutic potential.

  5. Titanium dioxide nanoparticles increase plasma glucose via reactive oxygen species-induced insulin resistance in mice.

    PubMed

    Hu, Hailong; Guo, Qian; Wang, Changlin; Ma, Xiao; He, Hongjuan; Oh, Yuri; Feng, Yujie; Wu, Qiong; Gu, Ning

    2015-10-01

    There have been few reports about the possible toxic effects of titanium dioxide (TiO2 ) nanoparticles on the endocrine system. We explored the endocrine effects of oral administration to mice of anatase TiO2 nanoparticles (0, 64 and 320 mg kg(-1) body weight per day to control, low-dose and high-dose groups, respectively, 7 days per week for 14 weeks). TiO2 nanoparticles were characterized by scanning and transmission electron microscopy (TEM) and dynamic light scattering (DLS), and their physiological distribution was investigated by inductively coupled plasma. Biochemical analyzes included plasma glucose, insulin, heart blood triglycerides (TG), free fatty acid (FFA), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6 and reactive oxygen species (ROS)-related markers (total SOD, GSH and MDA). Phosphorylation of IRS1, Akt, JNK1, and p38 MAPK were analyzed by western blotting. Increased titanium levels were found in the liver, spleen, small intestine, kidney and pancreas. Biochemical analyzes showed that plasma glucose significantly increased whereas there was no difference in plasma insulin secretion. Increased ROS levels were found in serum and the liver, as evidenced by reduced total SOD activity and GSH level and increased MDA content. Western blotting showed that oral administration of TiO2 nanoparticles induced insulin resistance (IR) in mouse liver, shown by increased phosphorylation of IRS1 (Ser307) and reduced phosphorylation of Akt (Ser473). The pathway by which TiO2 nanoparticles increase ROS-induced IR were included in the inflammatory response and phosphokinase, as shown by increased serum levels of TNF-α and IL-6 and increased phosphorylation of JNK1 and p38 MAPK in liver. These results show that oral administration of TiO2 nanoparticles increases ROS, resulting in IR and increasing plasma glucose in mice.

  6. Feedback-induced bistability of an optically levitated nanoparticle: A Fokker-Planck treatment

    NASA Astrophysics Data System (ADS)

    Ge, Wenchao; Rodenburg, Brandon; Bhattacharya, M.

    2016-08-01

    Optically levitated nanoparticles have recently emerged as versatile platforms for investigating macroscopic quantum mechanics and enabling ultrasensitive metrology. In this paper we theoretically consider two damping regimes of an optically levitated nanoparticle cooled by cavityless parametric feedback. Our treatment is based on a generalized Fokker-Planck equation derived from the quantum master equation presented recently and shown to agree very well with experiment [B. Rodenburg, L. P. Neukirch, A. N. Vamivakas, and M. Bhattacharya, Quantum model of cooling and force sensing with an optically trapped nanoparticle, Optica 3, 318 (2016), 10.1364/OPTICA.3.000318]. For low damping, we find that the resulting Wigner function yields the single-peaked oscillator position distribution and recovers the appropriate energy distribution derived earlier using a classical theory and verified experimentally [J. Gieseler, R. Quidant, C. Dellago, and L. Novotny, Dynamic relaxation of a levitated nanoparticle from a non-equilibrium steady state, Nat. Nano. 9, 358 (2014), 10.1038/nnano.2014.40]. For high damping, in contrast, we predict a double-peaked position distribution, which we trace to an underlying bistability induced by feedback. Unlike in cavity-based optomechanics, stochastic processes play a major role in determining the bistable behavior. To support our conclusions, we present analytical expressions as well as numerical simulations using the truncated Wigner function approach. Our work opens up the prospect of developing bistability-based devices, characterization of phase-space dynamics, and investigation of the quantum-classical transition using levitated nanoparticles.

  7. Laser-induced periodic alignment of Ag nanoparticles in soda-lime glass.

    PubMed

    Goutaland, François; Colombier, Jean-Philippe; Sow, Mohamed Cherif; Ollier, Nadège; Vocanson, Francis

    2013-12-30

    One-, two- or three-dimensional arrays of closely spaced silver nanoparticles may lead to new optical properties, due to short or long range coupling between their resonant surface plasmons, so that the spatially controlled growth of silver nanoparticles provides an efficient way to tune their optical properties. Towards this way, we present here the periodic pattern of a glass surface with silver nanoparticles by continuous ultraviolet laser exposure. The formation of the 160 nm period pattern is well described by an interference-based model which agrees with the experimental conclusions, mainly obtained by various forms of microscopy. Statistical approach based on the autocorrelation function gives quantitative description about the quality of the order in the periodic structure and about the nanoparticles averaged diameter (80 nm). We also present the optical extinction spectrum of the Laser Induced Periodic Surface Structure (LIPSS)-containing area of the glass, which unusually shows several bands in the visible range. The period of 160 nm of the periodic structure is short enough to allow coupling between nanoparticles, which makes it a possible candidate for plasmon-based optical applications.

  8. Eupafolin nanoparticle improves acute renal injury induced by LPS through inhibiting ROS and inflammation.

    PubMed

    Zhang, Hao; Chen, Ming-Kun; Li, Ke; Hu, Cheng; Lu, Min-Hua; Situ, Jie

    2017-01-01

    Acute renal injury is a common severe clinical syndrome, occurring in many clinical situations. It is necessary to explore effective drugs to treat it. Eupafolin is a flavonoid compound, derived from Phyla nodiflora, which has been previously reported to possess a variety of pharmacological activities, including anti-inflammatory and antioxidant effects. However, it is known little about how it works in acute renal injury. Also, eupafolin is characterized by skin penetration and poor water solubility, limiting its clinical applications. Thus, we synthesized an eupafolin nanoparticle delivery system. We found that eupafolin nanoparticle could address the physicochemical defects of raw eupafolin and increase water solubility without any toxicity to normal renal cells via reducing particle size. Eupafolin nanoparticle attenuated LPS-induced acute renal injury in mice through inhibiting oxidative stress and inflammation accompanied with up-regulated SOD activity and down-regulated pro-inflammatory cytokines. Additionally, inactivation of NF-κB and MAPKs of p38, ERK1/2 and JNK signaling pathways was a main molecular mechanism by which eupafolin nanoparticle improved renal injury. Together, eupafolin nanoparticle exhibits effective anti-oxidant and anti-inflammatory activities, which could be used as a potential drug to ameliorate acute renal injury clinically.

  9. Gamma irradiation induced in situ synthesis of lead sulfide nanoparticles in poly(vinyl alcohol) hydrogel

    NASA Astrophysics Data System (ADS)

    Kuljanin-Jakovljević, Jadranka Ž.; Radosavljević, Aleksandra N.; Spasojević, Jelena P.; Carević, Milica V.; Mitrić, Miodrag N.; Kačarević-Popović, Zorica M.

    2017-01-01

    In this study, the nanocomposites based on semiconductor lead sulfide (PbS) nanoparticles and poly(vinyl alcohol) (PVA) were investigated. The gamma irradiation induced in situ incorporation of PbS nanoparticles in crosslinked polymer network i.e. PVA hydrogel was performed. PVA hydrogel was previously obtained also under the influence of gamma irradiation. UV-Vis absorption and X-ray diffraction measurements were employed to investigate optical and structural properties of PbS nanoparticles, respectively, and obtained results indicates the presence of nanoparticles with approximately 6 nm in diameter and face centered cubic rock-salt crystal structure. The porous morphology was confirmed by scanning electron microscopy. Swelling data revealed that investigated hydrogels (PVA and PbS-PVA nanocomposite) shows non-Fickian diffusion, indicating that both diffusion and polymer relaxation processes controlled the fluid transport. The values of diffusion coefficients have an order of magnitude 10-9 cm2/s (typical values for water diffusion in polymers) and the best fit with the experimental results showed the Etters approximation. Comparing the thermal properties of PbS-PVA xerogel nanocomposite with PVA xerogel it was observed that incorporation of PbS nanoparticles in crosslinked PVA matrix just slightly enhanced the thermal stability of nanocomposite.

  10. Laser-induced in situ synthesis of Pd and Pt nanoparticles on polymer films

    NASA Astrophysics Data System (ADS)

    Mehrabanian, Mehran; Morselli, Davide; Caputo, Gianvito; Scarpellini, Alice; Palazon, Francisco; Athanassiou, Athanassia; Fragouli, Despina

    2016-12-01

    We present the localized in situ formation of Pd and Pt nanoparticles embedded in chitosan solid films. This is achieved by the photo-induced reduction of metallic precursors, previously incorporated in chitosan films, through controlled UV pulsed laser irradiation. Interestingly, at high number of laser pulses, Pd and Pt follow different formation pathways, contrary to their common photoreduction mechanism occurring at low irradiation pulses. Specifically, in the case of the Pd, a photofragmentation process takes place fracturing the previously formed nanoparticles into smaller ones; whereas in the case of Pt, the prolonged irradiation promotes the nanoparticles agglomeration. The combination of both precursors in a binary solid system results in the combined formation of both Pd and Pt nanoparticles in the polymer film upon laser irradiation. The herein reported approach is an efficient and precise tool to generate size- and density-controlled Pd and Pt nanoparticles in desired areas of polymeric films, rendering this method a potential candidate for the fabrication of flexible polymeric devices for gas-sensing or electro-catalysis applications.

  11. Transient Mild Hyperthermia Induces E-selectin Mediated Localization of Mesoporous Silicon Vectors in Solid Tumors

    PubMed Central

    Kirui, Dickson K.; Mai, Juahua; Palange, Anna-Lisa; Qin, Guoting; van de Ven, Anne L.; Liu, Xuewu; Shen, Haifa; Ferrari, Mauro

    2014-01-01

    Background Hyperthermia treatment has been explored as a strategy to overcome biological barriers that hinder effective drug delivery in solid tumors. Most studies have used mild hyperthermia treatment (MHT) to target the delivery of thermo-sensitive liposomes carriers. Others have studied its application to permeabilize tumor vessels and improve tumor interstitial transport. However, the role of MHT in altering tumor vessel interfacial and adhesion properties and its relationship to improved delivery has not been established. In the present study, we evaluated effects of MHT treatment on tumor vessel flow dynamics and expression of adhesion molecules and assessed enhancement in particle localization using mesoporous silicon vectors (MSVs). We also determined the optimal time window at which maximal accumulation occur. Results In this study, using intravital microscopy analyses, we showed that temporal mild hyperthermia (∼1 W/cm2) amplified delivery and accumulation of MSVs in orthotopic breast cancer tumors. The number of discoidal MSVs (1000×400 nm) adhering to tumor vasculature increased 6-fold for SUM159 tumors and 3-fold for MCF-7 breast cancer tumors. By flow chamber experiments and Western blotting, we established that a temporal increase in E-selectin expression correlated with enhanced particle accumulation. Furthermore, MHT treatment was shown to increase tumor perfusion in a time-dependent fashion. Conclusions Our findings reveal that well-timed mild hyperthermia treatment can transiently elevate tumor transport and alter vascular adhesion properties and thereby provides a means to enhance tumor localization of non-thermally sensitive particles such as MSVs. Such enhancement in accumulation could be leveraged to increase therapeutic efficacy and reduce drug dosing in cancer therapy. PMID:24558362

  12. Iron oxide nanoparticles induce Pseudomonas aeruginosa growth, induce biofilm formation, and inhibit antimicrobial peptide function†

    PubMed Central

    Borcherding, Jennifer; Baltrusaitis, Jonas; Chen, Haihan; Stebounova, Larissa; Wu, Chia-Ming; Rubasinghege, Gayan; Mudunkotuwa, Imali A.; Caraballo, Juan Carlos; Zabner, Joseph

    2014-01-01

    Given the increased use of iron-containing nanoparticles in a number of applications, it is important to understand any effects that iron-containing nanoparticles can have on the environment and human health. Since iron concentrations are extremely low in body fluids, there is potential that iron-containing nanoparticles may influence the ability of bacteria to scavenge iron for growth, affect virulence and inhibit antimicrobial peptide (AMP) function. In this study, Pseudomonas aeruginosa (PA01) and AMPs were exposed to iron oxide nanoparticles, hematite (α-Fe2O3), of different sizes ranging from 2 to 540 nm (2 ± 1, 43 ± 6, 85 ± 25 and 540 ± 90 nm) in diameter. Here we show that the greatest effect on bacterial growth, biofilm formation, and AMP function impairment is found when exposed to the smallest particles. These results are attributed in large part to enhanced dissolution observed for the smallest particles and an increase in the amount of bioavailable iron. Furthermore, AMP function can be additionally impaired by adsorption onto nanoparticle surfaces. In particular, lysozyme readily adsorbs onto the nanoparticle surface which can lead to loss of peptide activity. Thus, this current study shows that co-exposure of nanoparticles and known pathogens can impact host innate immunity. Therefore, it is important that future studies be designed to further understand these types of impacts. PMID:25221673

  13. Drug-loaded nanoparticles induce gene expression in human pluripotent stem cell derivatives

    NASA Astrophysics Data System (ADS)

    Gajbhiye, Virendra; Escalante, Leah; Chen, Guojun; Laperle, Alex; Zheng, Qifeng; Steyer, Benjamin; Gong, Shaoqin; Saha, Krishanu

    2013-12-01

    Tissue engineering and advanced manufacturing of human stem cells requires a suite of tools to control gene expression spatiotemporally in culture. Inducible gene expression systems offer cell-extrinsic control, typically through addition of small molecules, but small molecule inducers typically contain few functional groups for further chemical modification. Doxycycline (DXC), a potent small molecule inducer of tetracycline (Tet) transgene systems, was conjugated to a hyperbranched dendritic polymer (Boltorn H40) and subsequently reacted with polyethylene glycol (PEG). The resulting PEG-H40-DXC nanoparticle exhibited pH-sensitive drug release behavior and successfully controlled gene expression in stem-cell-derived fibroblasts with a Tet-On system. While free DXC inhibited fibroblast proliferation and matrix metalloproteinase (MMP) activity, PEG-H40-DXC nanoparticles maintained higher fibroblast proliferation levels and MMP activity. The results demonstrate that the PEG-H40-DXC nanoparticle system provides an effective tool to controlling gene expression in human stem cell derivatives.Tissue engineering and advanced manufacturing of human stem cells requires a suite of tools to control gene expression spatiotemporally in culture. Inducible gene expression systems offer cell-extrinsic control, typically through addition of small molecules, but small molecule inducers typically contain few functional groups for further chemical modification. Doxycycline (DXC), a potent small molecule inducer of tetracycline (Tet) transgene systems, was conjugated to a hyperbranched dendritic polymer (Boltorn H40) and subsequently reacted with polyethylene glycol (PEG). The resulting PEG-H40-DXC nanoparticle exhibited pH-sensitive drug release behavior and successfully controlled gene expression in stem-cell-derived fibroblasts with a Tet-On system. While free DXC inhibited fibroblast proliferation and matrix metalloproteinase (MMP) activity, PEG-H40-DXC nanoparticles maintained

  14. Graphene wrinkling induced by monodisperse nanoparticles: facile control and quantification

    PubMed Central

    Vejpravova, Jana; Pacakova, Barbara; Endres, Jan; Mantlikova, Alice; Verhagen, Tim; Vales, Vaclav; Frank, Otakar; Kalbac, Martin

    2015-01-01

    Controlled wrinkling of single-layer graphene (1-LG) at nanometer scale was achieved by introducing monodisperse nanoparticles (NPs), with size comparable to the strain coherence length, underneath the 1-LG. Typical fingerprint of the delaminated fraction is identified as substantial contribution to the principal Raman modes of the 1-LG (G and G’). Correlation analysis of the Raman shift of the G and G’ modes clearly resolved the 1-LG in contact and delaminated from the substrate, respectively. Intensity of Raman features of the delaminated 1-LG increases linearly with the amount of the wrinkles, as determined by advanced processing of atomic force microscopy data. Our study thus offers universal approach for both fine tuning and facile quantification of the graphene topography up to ~60% of wrinkling. PMID:26530787

  15. Carbon Black and Titanium Dioxide Nanoparticles Induce Distinct Molecular Mechanisms of Toxicity

    PubMed Central

    Boland, Sonja; Hussain, Salik; Baeza-Squiban, Armelle

    2014-01-01

    Increasing evidence link nanomaterials with adverse biological outcomes and due to the variety of applications and potential human exposures to nanoparticles it is thus important to evaluate their toxicity for the risk assessment of workers and consumers. It is crucial to understand the underlying mechanisms of their toxicity as observation of similar effects after different nanomaterial exposures does not reflect similar intracellular processing and organelle interactions. A thorough understanding of mechanisms is not only needed for accurate prediction of potential toxicological impacts but also for the development of safer nanoapplications by modulating the physico-chemical characteristics. Furthermore biomedical applications may also take advantage of an in depth knowledge about the mode of action of nanotoxicity to design new nanoparticle-derived drugs. In the present manuscript we discuss the similarities and differences in molecular pathways of toxicity after carbon black and TiO2 nanoparticle exposures and identify the main toxicity mechanisms induced by these two nanoparticles which may also be indicative for the mode of action of other insoluble nanomaterials. We address the translocation, cell death induction, genotoxicity and inflammation induced by titanium dioxide and carbon black nanoparticles which depend on their internalisation, ROS production capacities and/or protein interactions. We summarise their distinct cellular mechanisms of toxicity and the crucial steps which may be targeted to avoid adverse effects or to induce them for nanomedical purposes. Several physico-chemical characteristics could influence these general toxicity pathways depicted here and the identification of common toxicity pathways could support the grouping of nanomaterials in terms of toxicity. PMID:25266826

  16. New findings of silica nanoparticles induced ER autophagy in human colon cancer cell

    PubMed Central

    Wei, Fujing; Wang, Yimin; Luo, Zewei; Li, Yu; Duan, Yixiang

    2017-01-01

    Nanoparticle-induced autophagy has been extensively studied, however, real time information about the endoplasmic reticulum involved autophagic process (ER autophagy) induced by nanomaterials remains unknown. In this work, silica nanoparticles (SNPs) were synthesized with characteristics of low toxicity, good biocompatibility and excellent water dispersibility to treat cells. Results show that either low concentration (10 μg/mL) or high concentration (200 μg/mL) of SNPs could increase the quantity of processing from microtubule-associated protein 1-light chain 3-I (LC3-I) to the other variant of LC3 (LC3-II). Interestingly, the level of autophagy induced by the SNPs is associated with the treated time but not the concentrations of SNPs. Importantly, for the first time, SNP accumulation in ER was discovered through co-localization analysis, which incurs ER autophagy. These new findings about SNPs-induced ER autophagy could open an effective way for securely designing silica-based nanoparticles and enable us to know more about ER autophagy. PMID:28195184

  17. Exposure to ZnO nanoparticles induces oxidative stress and cytotoxicity in human colon carcinoma cells

    SciTech Connect

    De Berardis, Barbara; Civitelli, Gabriele; Condello, Maria; Lista, Pasquale; Pozzi, Roberta; Arancia, Giuseppe; Meschini, Stefania

    2010-08-01

    Engineered nanoparticles offer great promise in many industrial and biomedical applications, however little information is available about gastrointestinal toxicity. The purpose of this study was to assess the cytotoxicity, oxidative stress, apoptosis and proinflammatory mediator release induced by ZnO nanoparticles on human colon carcinoma LoVo cells. The biological activity of these particles was related to their physico-chemical characteristics. The physico-chemical characteristics were evaluated by analytical electron microscopy. The cytotoxicity was determined by growth curves and water-soluble tetrazolium assay. The reactive oxygen species production, cellular glutathione content, changes of mitochondrial membrane potential and apoptosis cell death were quantified by flow cytometry. The inflammatory cytokines were evaluated by enzyme-linked immunoadsorbent assay. Treatment with ZnO (5 {mu}g/cm{sup 2} corresponding to 11.5 {mu}g/ml) for 24 h induced on LoVo cells a significant decrease of cell viability, H{sub 2}O{sub 2}/OH{center_dot} increase, O2{sup -{center_dot}} and GSH decrease, depolarization of inner mitochondrial membranes, apoptosis and IL-8 release. Higher doses induced about 98% of cytotoxicity already after 24 h of treatment. The experimental data show that oxidative stress may be a key route in inducing the cytotoxicity of ZnO nanoparticles in colon carcinoma cells. Moreover, the study of the relationship between toxicological effects and physico-chemical characteristics of particles suggests that surface area does not play a primary role in the cytotoxicity.

  18. Magnet-induced temporary superhydrophobic coatings from one-pot synthesized hydrophobic magnetic nanoparticles.

    PubMed

    Fang, Jian; Wang, Hongxia; Xue, Yuhua; Wang, Xungai; Lin, Tong

    2010-05-01

    In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe(3)O(4) magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe(2+)/Fe(3+) under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172 degrees , and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is the formation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas.

  19. Electron beam induced synthesis of uranium dioxide nanoparticles: Effect of solvent composition

    NASA Astrophysics Data System (ADS)

    Rath, M. C.; Keny, S. J.; Naik, D. B.

    2016-09-01

    The effect of various compositions of solvents was investigated on the electron beam induced synthesis of uranium dioxide, UO2 nanoparticles. The synthesis was carried out at different pHs from 2 to 7 in the aqueous solutions containing 10 mM uranyl nitrate and 10% 2-propanol. The formation of UO2 nanoparticles was found to occur only in the pH range from 2.5 to 3.7. Experiments were also carried out in the aqueous solutions containing various other alcohols (10% v/v) such as methanol, ethanol, 1-propanol, 1-butanol or tert-butanol as well as in solutions containing 10 mM sodium formate at pH 3.4. The formation of UO2 nanoparticles in the aqueous solutions was found to occur only in the presence of ethanol, 1-propanol, 2-propanol or 1-butanol. It is therefore confirmed that the electron beam induced synthesis of UO2 nanoparticles strongly depends on the solvent compositions as well as the pH of the medium.

  20. Childhood trauma are not associated with the intensity of transient cocaine induced psychotic symptoms.

    PubMed

    Karsinti, Emily; Jarroir, Marine; Zerdazi, El-Hadi; Bloch, Vanessa; Dupuy, Gaël; Belforte, Beatriz; Coeuru, Philippe; Plat, Arnaud; Deschenau, Alice; Cottencin, Olivier; Gay, Aurelia; Lack, Philippe; Pelissier-Alicot, Anne-Laure; Bellivier, Frank; Lépine, Jean-Pierre; Brousse, George; Vorspan, Florence

    2015-08-30

    A personal history of childhood trauma has been associated with the severity of psychotic symptoms in several disorders. We evaluated retrospectively cocaine-induced psychotic symptoms with the SAPS-CIP and childhood trauma with the CTQ in a clinical sample of 144 cocaine users. The SAPS-CIP score was not statistically associated with the presence or number or intensity of trauma, but was associated with rapid routes of administration (intravenous and smoked) and with frequent cocaine use.

  1. Transient elastic deformation detection on the metal surface induced by nanosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Tong, Yanqun; Huang, Jianyu; Wu, Xiaoyi; Shi, Lin

    2016-10-01

    It is difficult to detect the elastic deformation on the metal surface induced by nanosecond laser pulse. Optical fiber sensor system is suitable for detecting the elastic deformation, which has many advantages such as the high sensitivity, fast speed (GHz), non-contact, non-loss and point-measurement. We set up the measuring system to analyze the deformation mechanism firstly. Then, the elastic deformation on the metal surface was investigated. The relation between the shock-wave and elastic deformation was analyzed. The result of the present work implicated that as the nanosecond laser pulse radiated to the metal surface, elastic deformation had a delay time which was around 320ns. And the deformation presented the damped oscillation law. The data of laser-induced plasma shock wave were fitted and the fitting degree was 97.696%.The variation law of laser-induced plasma shock-wave was obtained. These results helped to make the laser removal applied to the manufacturing technique better.

  2. Modelling for Transient Optically Induced Metal - Transitions in Narrow-Gap Semiconductors and Semimetals.

    NASA Astrophysics Data System (ADS)

    Vidal, Jordina

    1994-01-01

    The theoretical work presented in this thesis is based on models developed to interpret a series of optical experiments with short-pulse lasers, which allow a time -domain study of phenomena on a sub-picosecond timescale. By means of a pump-probe technique, we observe large amplitude oscillations in the time domain reflectivity response of a series of narrow-gap semiconductors and semimetals. The oscillations have the frequency of the fully-symmetric optical phonon mode of the system, and are maximally displaced from their midpoint value at zero time delay between pump and probe. These features indicate that a coherent phonon vibration is generated in these materials via an electronic excitation at different points of the Brillouin zone, which displaces instantaneously the equilibrium positions of the atoms. It is precisely this generation of coherent phonons that makes the time-domain technique distinct from conventional frequency domain techniques, such as Raman and neutron scattering. Using a range of theoretical techniques, from nearly free electron models to state-of-the art ab initio calculations, I have made quantitative microscopic evaluations of the coherent phonon phenomenon. The studies focus on two unique aspects of having such coherent atomic vibrations in a narrow gap material, with special emphasis on the group V semimetals Sb and Bi. First of all, I have performed dynamical band structure calculations, as a function of the coherent atomic motion, in order to inspect the possibility of a transient metal-insulator transition at a terahertz frequency. Secondly, I have calculated the evolution of the displaced atoms in quasi-equilibrium with the laser -excited carriers, as the electron-ion coupled system returns to its ground state equilibrium. These calculations are fundamental, insofar they provide a quantitative microscopic description of the coherent phonon phenomenon. Moreover, the predicted magnitude of the atomic displacements, and the resulting

  3. Repeated exposure of adult rats to transient oxidative stress induces various long-lasting alterations in cognitive and behavioral functions.

    PubMed

    Iguchi, Yoshio; Kosugi, Sakurako; Nishikawa, Hiromi; Lin, Ziqiao; Minabe, Yoshio; Toda, Shigenobu

    2014-01-01

    Exposure of neonates to oxidative stress may increase the risk of psychiatric disorders such as schizophrenia in adulthood. However, the effects of moderate oxidative stress on the adult brain are not completely understood. To address this issue, we systemically administrated 2-cyclohexen-1-one (CHX) to adult rats to transiently reduce glutathione levels. Repeated administration of CHX did not affect the acquisition or motivation of an appetitive instrumental behavior (lever pressing) rewarded by a food outcome under a progressive ratio schedule. In addition, response discrimination and reversal learning were not affected. However, acute CHX administration blunted the sensitivity of the instrumental performance to outcome devaluation, and this effect was prolonged in rats with a history of repeated CHX exposure, representing pro-depression-like phenotypes. On the other hand, repeated CHX administration reduced immobility in forced swimming tests and blunted acute cocaine-induced behaviors, implicating antidepressant-like effects. Multivariate analyses segregated a characteristic group of behavioral variables influenced by repeated CHX administration. Taken together, these findings suggest that repeated administration of CHX to adult rats did not cause a specific mental disorder, but it induced long-term alterations in behavioral and cognitive functions, possibly related to specific neural correlates.

  4. Dendritic cell-based immunotherapy induces transient clinical response in advanced rat fibrosarcoma - comparison with preventive anti-tumour vaccination.

    PubMed

    Kucera, A; Pýcha, K; Pajer, P; Spísek, R; Skába, R

    2009-01-01

    In this study we present the models of preventive and therapeutic vaccination of sarcoma-bearing rats with dendritic cells that present tumour antigens from killed tumour cells. We present the characteristics of dendritic cell-based vaccine and its capacity to induce anti-tumour immune response both in vitro and in vivo. We show that preventive vaccination efficiently prevents tumour growth. On the other hand, vaccination of rats with established tumours did not lead to eradication of the tumours. Despite the induction of a vigorous immune response after administration of dendritic cell-based vaccine and transient decrease in tumour progression, tumours eventually resumed their growth and animals vaccinated with dendritic cells succumbed to cancer. In both settings, preventive and therapeutic, dendritic cell-based vaccination induced a vigorous tumour-specific T-cell response. These results argue for the timing of cancer immunotherapy to the stages of low tumour load. Immunotherapy initiated at the stage of minimal residual disease, after reduction of tumour load by other modalities, will have much better chance to offer a clinical benefit to cancer patients than the immunotherapy at the stage of metastatic disease.

  5. Protein–Ligand Interaction Detection with a Novel Method of Transient Induced Molecular Electronic Spectroscopy (TIMES): Experimental and Theoretical Studies

    PubMed Central

    2016-01-01

    Protein–ligand interaction detection without disturbances (e.g., surface immobilization, fluorescent labeling, and crystallization) presents a key question in protein chemistry and drug discovery. The emergent technology of transient induced molecular electronic spectroscopy (TIMES), which incorporates a unique design of microfluidic platform and integrated sensing electrodes, is designed to operate in a label-free and immobilization-free manner to provide crucial information for protein–ligand interactions in relevant physiological conditions. Through experiments and theoretical simulations, we demonstrate that the TIMES technique actually detects protein–ligand binding through signals generated by surface electric polarization. The accuracy and sensitivity of experiments were demonstrated by precise measurements of dissociation constant of lysozyme and N-acetyl-d-glucosamine (NAG) ligand and its trimer, NAG3. Computational fluid dynamics (CFD) computation is performed to demonstrate that the surface’s electric polarization signal originates from the induced image charges during the transition state of surface mass transport, which is governed by the overall effects of protein concentration, hydraulic forces, and surface fouling due to protein adsorption. Hybrid atomistic molecular dynamics (MD) simulations and free energy computation show that ligand binding affects lysozyme structure and stability, producing different adsorption orientation and surface polarization to give the characteristic TIMES signals. Although the current work is focused on protein–ligand interactions, the TIMES method is a general technique that can be applied to study signals from reactions between many kinds of molecules. PMID:27924312

  6. A case of esomeprazole-induced transient diabetes and hepatitis: the role of liver inflammation in the pathogenesis of insulin resistance.

    PubMed

    Zaccardi, Francesco; Pitocco, Dario; Martini, Francesca; Caputo, Salvatore; Miele, Luca; Grieco, Antonio; Ghirlanda, Giovanni

    2014-02-01

    We describe a case report of a patient who developed transient type 2 diabetes after a drug-induced (esomeprazole) sub-acute hepatitis. This case evidences the pathophysiological relevance, also in humans, of liver inflammation in the pathogenesis of type 2 diabetes.

  7. Weaning induces both transient and long-lasting modifications of absorptive, secretory, and barrier properties of piglet intestine.

    PubMed

    Boudry, Gaëlle; Péron, Vincent; Le Huërou-Luron, Isabelle; Lallès, Jean Paul; Sève, Bernard

    2004-09-01

    This study investigated intestinal physiology of piglets at weaning. Piglets (n = 60) weaned at 21 d were food deprived for 2 d and then tube-fed using 2 different diets (a conventional diet vs. a wheat-enriched diet). They were slaughtered at d 0, 2, 5, 8, or 15 postweaning. Jejunum, ileum, and colon were mounted in Ussing chambers. In addition, segments of the proximal jejunum of 4 growing pigs were studied 35 d after weaning. Secretory function was assessed by basal short-circuit current (Isc) and secretagogue-stimulated Isc. Glucose absorption was measured by the increase in Isc after the addition of glucose. Epithelial barrier function was measured by transmucosal resistance (R) and horseradish peroxidase (HRP) fluxes across the epithelium. There were no significant differences between the pigs fed the 2 diets for any of the parameters studied. As already reported, a transient villous atrophy was observed. At the same time, we observed an increased basal Isc in jejunum and colon, increased glucose absorption and a dramatic drop of R in jejunum. These parameters had returned to preweaning values by d 5. Weaning was also followed by long-lasting modifications. In jejunum, responses to the secretagogues and glucose absorption were decreased at wk 2 after weaning and were not different between d 15 and 35. Ileal transmucosal resistance increased on d 5 and was stable thereafter. HRP flux in jejunum declined on d 2 and stayed at this low level throughout the experiment. We conclude that weaning induces transient dramatic changes in intestinal physiology but is also a period of maturation of the intestine.

  8. Comparative research on “high currents” induced by single event latch-up and transient-induced latch-up

    NASA Astrophysics Data System (ADS)

    Chen, Rui; Han, Jian-Wei; Zheng, Han-Sheng; Yu, Yong-Tao; Shangguang, Shi-Peng; Feng, Guo-Qiang; Ma, Ying-Qi

    2015-04-01

    By using the pulsed laser single event effect facility and electro-static discharge (ESD) test system, the characteristics of the “high current”, relation with external stimulus and relevance to impacted modes of single event latch-up (SEL) and transient-induced latch-up (TLU) are studied, respectively, for a 12-bit complementary metal-oxide semiconductor (CMOS) analog-to-digital converter. Furthermore, the sameness and difference in physical mechanism between “high current” induced by SEL and that by TLU are disclosed in this paper. The results show that the minority carrier diffusion in the PNPN structure of the CMOS device which initiates the active parasitic NPN and PNP transistors is the common reason for the “high current” induced by SEL and for that by TLU. However, for SEL, the minority carrier diffusion is induced by the ionizing radiation, and an underdamped sinusoidal voltage on the supply node (the ground node) is the cause of the minority carrier diffusion for TLU. Project supported by the National Natural Science Foundation of China (Grant No. 41304148).

  9. Roles of PTEN-induced putative kinase 1 and dynamin-related protein 1 in transient global ischemia-induced hippocampal neuronal injury

    SciTech Connect

    Chen, Shang-Der; Lin, Tsu-Kung; Yang, Ding-I.; Lee, Su-Ying; Shaw, Fu-Zen; Liou, Chia-Wei; Chuang, Yao-Chung

    2015-05-01

    Recent studies showed that increased mitochondrial fission is an early event of cell death during cerebral ischemia and dynamin-related protein 1 (Drp1) plays an important role in mitochondrial fission, which may be regulated by PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine/threonine-protein kinase thought to protect cells from stress-induced mitochondrial dysfunction and regulate mitochondrial fission. However, the roles of PINK1 and Drp1 in hippocampal injury caused by transient global ischemia (TGI) remain unknown. We therefore tested the hypothesis that TGI may induce PINK1 causing downregulation of Drp1 phosphorylation to enhance hippocampal neuronal survival, thus functioning as an endogenous neuroprotective mechanism. We found progressively increased PINK1 expression in the hippocampal CA1 subfield1-48 h following TGI, reaching the maximal level at 4 h. Despite lack of changes in the expression level of total Drp1 and phosphor-Drp1 at Ser637, TGI induced a time-dependent increase of Drp1 phosphorlation at Ser616 that peaked after 24 h. Notably, PINK1-siRNA increased p-Drp1(Ser616) protein level in hippocampal CA1 subfield 24 h after TGI. The PINK1 siRNA also aggravated the TGI-induced oxidative DNA damage with an increased 8-hydroxy-deoxyguanosine (8-OHdG) content in hippocampal CA1 subfield. Furthermore, PINK1 siRNA also augmented TGI-induced apoptosis as evidenced by the increased numbers of TUNEL-positive staining and enhanced DNA fragmentation. These findings indicated that PINK1 is an endogenous protective mediator vital for neuronal survival under ischemic insult through regulating Drp1 phosphorylation at Ser616. - Highlights: • Transient global ischemia increases expression of PINK1 and p-Drp1 at Ser616 in hippocampal CA1 subfield. • PINK1-siRNA decreases PINK1 expression but increases p-Drp1 at Ser616 in hippocampal CA1 subfield. • PINK1-siRNA augments oxidative stress and neuronal damage in hippocampal CA1 subfield.

  10. Transient coherence oscillation induced by a detuned Raman field in a rubidium {lambda} system

    SciTech Connect

    Park, Sung Jong; Cho, Hyuck; Kwon, Taeg Yong; Lee, Ho Seong

    2004-02-01

    The temporal evolution of coherent population trapping (CPT) was observed in rubidium atomic vapor when sudden changes were made to the detuning of a weak Raman field. The subsequent creation and destruction of CPT are caused by the temporal oscillations of optically induced Raman coherence, with their period depending on the Raman detuning. The oscillating signal was observed over a time of order of tens of milliseconds, and the dependence of the relaxation time on the cell temperature and laser power were investigated. The main features of the experimental observations were well explained by the time-dependent density-matrix equations.

  11. Robust Measurement of Thin-Film Photovoltaic Modules Exhibiting Light-Induced Transients: Preprint

    SciTech Connect

    Deceglie, Michael, G.; Silverman, Timothy J.; Marion, Bill; Kurtz, Sarah R.

    2015-09-09

    Light-induced changes to the current-voltage characteristic of thin-film photovoltaic modules (i.e. light-soaking effects) frustrate the repeatable measurement of their operating power. We describe best practices for mitigating, or stabilizing, light-soaking effects for both CdTe and CIGS modules to enable robust, repeatable, and relevant power measurements. We motivate the practices by detailing how modules react to changes in different stabilization methods. We also describe and demonstrate a method for validating alternative stabilization procedures, such as those relying on forward bias in the dark. Reliable measurements of module power are critical for qualification testing, reliability testing, and power rating.

  12. Robust measurement of thin-film photovoltaic modules exhibiting light-induced transients

    NASA Astrophysics Data System (ADS)

    Deceglie, Michael G.; Silverman, Timothy J.; Marion, Bill; Kurtz, Sarah R.

    2015-09-01

    Light-induced changes to the current-voltage characteristic of thin-film photovoltaic modules (i.e. light-soaking effects) frustrate the repeatable measurement of their operating power. We describe best practices for mitigating, or stabilizing, light-soaking effects for both CdTe and CIGS modules to enable robust, repeatable, and relevant power measurements. We motivate the practices by detailing how modules react to changes in different stabilization methods. We also describe and demonstrate a method for validating alternative stabilization procedures, such as those relying on forward bias in the dark. Reliable measurements of module power are critical for qualification testing, reliability testing, and power rating.

  13. Emulsification-Induced Homohelicity in Racemic Helical Polymer for Preparing Optically Active Helical Polymer Nanoparticles.

    PubMed

    Zhao, Biao; Deng, Jinrui; Deng, Jianping

    2016-04-01

    Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic helical polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic helical polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic helical polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally helical polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally helical polymer-derived optically active nanoparticles based on racemic helical polymers.

  14. Self-healable and reversible liposome leakage by citrate-capped gold nanoparticles: probing the initial adsorption/desorption induced lipid phase transition

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Liu, Juewen

    2015-09-01

    We herein report that the adsorption/desorption of citrate-capped gold nanoparticles (AuNPs) transiently causes leakage in fluid phase DOPC liposomes, while the liposomes do not leak with AuNPs capped with mercaptopropionic acid (MPA). Leakage also fails to occur for gel phase DPPC liposomes. Citrate-capped (but not MPA-capped) AuNPs raise the phase transition temperature of DPPC. We conclude that citrate-capped AuNPs interact with the PC liposomes very strongly, inducing a local fluid-to-gel lipid phase transition for DOPC. Leakage takes place during this transition, and the membrane integrity is resumed after the transition. Citrate-capped AuNPs allow stronger van der Waals forces than MPA-capped AuNPs with PC liposomes, since the latter are separated from the liposome surface by the ~0.3 nm MPA layer.We herein report that the adsorption/desorption of citrate-capped gold nanoparticles (AuNPs) transiently causes leakage in fluid phase DOPC liposomes, while the liposomes do not leak with AuNPs capped with mercaptopropionic acid (MPA). Leakage also fails to occur for gel phase DPPC liposomes. Citrate-capped (but not MPA-capped) AuNPs raise the phase transition temperature of DPPC. We conclude that citrate-capped AuNPs interact with the PC liposomes very strongly, inducing a local fluid-to-gel lipid phase transition for DOPC. Leakage takes place during this transition, and the membrane integrity is resumed after the transition. Citrate-capped AuNPs allow stronger van der Waals forces than MPA-capped AuNPs with PC liposomes, since the latter are separated from the liposome surface by the ~0.3 nm MPA layer. Electronic supplementary information (ESI) available: Methods, TEM, UV-vis and DLS data. See DOI: 10.1039/c5nr04805b

  15. A non-linear induced polarization effect on transient electromagnetic soundings

    NASA Astrophysics Data System (ADS)

    Hallbauer-Zadorozhnaya, Valeriya Yu.; Santarato, Giovanni; Abu Zeid, Nasser; Bignardi, Samuel

    2016-10-01

    In a TEM survey conducted for characterizing the subsurface for geothermal purposes, a strong induced polarization effect was recorded in all collected data. Surprisingly, anomalous decay curves were obtained in part of the sites, whose shape depended on the repetition frequency of the exciting square waveform, i.e. on current pulse length. The Cole-Cole model, besides being not directly related to physical parameters of rocks, was found inappropriate to model the observed distortion, due to induced polarization, because this model is linear, i.e. it cannot fit any dependence on current pulse. This phenomenon was investigated and explained as due to the presence of membrane polarization linked to constrictivity of (fresh) water-saturated pores. An algorithm for mathematical modeling of TEM data was then developed to fit this behavior. The case history is then discussed: 1D inversion, which accommodates non-linear effects, produced models that agree quite satisfactorily with resistivity and chargeability models obtained by an electrical resistivity tomography carried out for comparison.

  16. In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection

    PubMed Central

    Barreda, F.-A.; Nicolas, C.; Sirven, J.-B.; Ouf, F.-X.; Lacour, J.-L.; Robert, E.; Benkoula, S.; Yon, J.; Miron, C.; Sublemontier, O.

    2015-01-01

    The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed. PMID:26498694

  17. In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection.

    PubMed

    Barreda, F-A; Nicolas, C; Sirven, J-B; Ouf, F-X; Lacour, J-L; Robert, E; Benkoula, S; Yon, J; Miron, C; Sublemontier, O

    2015-10-26

    The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed.

  18. Cytotoxicity and oxidative stress induced by different metallic nanoparticles on human kidney cells

    PubMed Central

    2011-01-01

    Background Some manufactured nanoparticles are metal-based and have a wide variety of applications in electronic, engineering and medicine. Until now, many studies have described the potential toxicity of NPs on pulmonary target, while little attention has been paid to kidney which is considered to be a secondary target organ. The objective of this study, on human renal culture cells, was to assess the toxicity profile of metallic nanoparticles (TiO2, ZnO and CdS) usable in industrial production. Comparative studies were conducted, to identify whether particle properties impact cytotoxicity by altering the intracellular oxidative status. Results Nanoparticles were first characterized by size, surface charge, dispersion and solubility. Cytotoxicity of NPs was then evaluated in IP15 (glomerular mesangial) and HK-2 (epithelial proximal) cell lines. ZnO and CdS NPs significantly increased the cell mortality, in a dose-dependent manner. Cytotoxic effects were correlated with the physicochemical properties of NPs tested and the cell type used. Analysis of reactive oxygen species and intracellular levels of reduced and oxidized glutathione revealed that particles induced stress according to their composition, size and solubility. Protein involved in oxidative stress such as NF-κb was activated with ZnO and CdS nanoparticles. Such effects were not observed with TiO2 nanoparticles. Conclusion On glomerular and tubular human renal cells, ZnO and CdS nanoparticles exerted cytotoxic effects that were correlated with metal composition, particle scale and metal solubility. ROS production and oxidative stress induction clearly indicated their nephrotoxic potential. PMID:21371295

  19. Transient Hepatic Overexpression of Insulin-Like Growth Factor 2 Induces Free Cholesterol and Lipid Droplet Formation

    PubMed Central

    Kessler, Sonja M.; Laggai, Stephan; Van Wonterghem, Elien; Gemperlein, Katja; Müller, Rolf; Haybaeck, Johannes; Vandenbroucke, Roosmarijn E.; Ogris, Manfred; Libert, Claude; Kiemer, Alexandra K.

    2016-01-01

    Although insulin-like growth factor 2 (IGF2) has been reported to be overexpressed in steatosis and steatohepatitis, a causal role of IGF2 in steatosis development remains elusive. Aim of our study was to decipher the role of IGF2 in steatosis development. Hydrodynamic gene delivery of an Igf2 plasmid used for transient Igf2 overexpression employing codon-optimized plasmid DNA resulted in a strong induction of hepatic Igf2 expression. The exogenously delivered Igf2 had no influence on endogenous Igf2 expression. The downstream kinase AKT was activated in Igf2 animals. Decreased ALT levels mirrored the cytoprotective effect of IGF2. Serum cholesterol was increased and sulfo-phospho-vanillin colorimetric assay confirmed lipid accumulation in Igf2-livers while no signs of inflammation were observed. Interestingly, hepatic cholesterol and phospholipids, determined by thin layer chromatography, and free cholesterol by filipin staining, were specifically increased. Lipid droplet (LD) size was not changed, but their number was significantly elevated. Furthermore, free cholesterol, which can be stored in LDs and has been reported to be critical for steatosis progression, was elevated in Igf2 overexpressing mice. Accordingly, Hmgcr/HmgCoAR was upregulated. To have a closer look at de novo lipid synthesis we investigated expression of the lipogenic transcription factor SREBF1 and its target genes. SREBF1 was induced and also SREBF1 target genes were slightly upregulated. Interestingly, the expression of Cpt1a, which is responsible for mitochondrial fatty acid oxidation, was induced. Hepatic IGF2 expression induces a fatty liver, characterized by increased cholesterol and phospholipids leading to accumulation of LDs. We therefore suggest a causal role for IGF2 in hepatic lipid accumulation. PMID:27199763

  20. Silver nanoparticle-induced degranulation observed with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

    2010-07-01

    Monitoring a degranulation process in a live mast cell is a quite important issue in immunology and pharmacology. Because the size of a granule is normally much smaller than the resolution limit of an optical microscope system, there is no direct real-time live cell imaging technique for observing degranulation processes except for fluorescence imaging techniques. In this research, we propose optical quantitative phase microscopy (QPM) as a new observation tool to study degranulation processes in a live mast cell without any fluorescence labeling. We measure the cell volumes and the cross sectional profiles (x-z plane) of an RBL-2H3 cell and a HeLa cell, before and after they are exposed to calcium ionophore A23187 and silver nanoparticles (AgNPs). We verify that the volume and the cross sectional line profile of the RBL-2H3 cell were changed significantly when it was exposed to A23187. When 50 μg/mL of AgNP is used instead of A23187, the measurements of cell volume and cross sectional profiles indicate that RBL-2H3 cells also follow degranulation processes. Degranulation processes for these cells are verified by monitoring the increase of intracellular calcium ([Ca2+]i) and histamine with fluorescent methods.

  1. Standing on a declining surface reduces transient prolonged standing induced low back pain development.

    PubMed

    Gallagher, Kaitlin M; Callaghan, Jack P

    2016-09-01

    While alternating standing position on a sloped surface has proven successful at reducing low back pain during standing, the purpose of this study was to evaluate standing solely on a declining surface to isolate the influence of the postural change. Seventeen participants performed two 75-min prolonged standing occupational simulations- level ground and declining surface. Fifty-three percent of participants (9/17) were categorized as pain developers during the level ground standing condition. For these same pain developers, their average maximum pain scores were 58% lower during sloped standing. All participants showed greater hip flexion, trunk-to-thigh angle flexion, and posterior translation of the trunk center of gravity when standing on the sloped surface. These postural changes could cause the muscles crossing the hip posteriorly to increase passive stiffness and assist with stabilizing the pelvis. This study stresses the importance of hip kinematics, not just lumbar spine posture, in reducing prolonged standing induced low back pain.

  2. Transient oxygen clathrate-like hydrate and water networks induced by magnetic fields.

    PubMed

    Ozeki, Sumio; Otsuka, Ichiro

    2006-10-19

    Recently, careful experiments of oxygen-dissolved pure water treated by high magnetic fields showed indirectly the existence of magnetic field-affecting water (MFA water), which brought about a decrease in the contact angle of water on metals, an increase in the electrolytic potential of water, inhibition of metal corrosion, and changes in the crystal structure of calcium carbonate due to magnetic treatment. Here we report the infrared and Raman spectroscopic evidence indicating quasi-stable structures in the MFA water; oxygen clathrate-like hydrate and developed water networks, which were induced by magnetic interactions while a vacuum-distilled water, followed by oxygen exposure, crossed a steady magnetic field. The mechanism of MFA water formation and survival under thermal fluctuation is a challenging problem for the science community.

  3. High-Speed Fluorescence Imaging and Intensity Profiling of Femtosecond-Induced Calcium Transients

    PubMed Central

    Cranfield, Charles G.; Gu, Min

    2006-01-01

    We have demonstrated a combined imaging system, where the physiology of biological specimens can be imaged and profiled at 10–20 frames per second whilst undergoing femtosecond laser irradiation. Individual GH3 cells labeled with the calcium fluorophore Fluo-3 were stimulated using a counter-propagating focused femtosecond beam with respect to the imaging system. As a result of the stimulation, calcium waves can be generated in COS cells, and laser-induced calcium oscillations are initiated in the GH3 cells. Single-photon fluorescence images and intensity profiles of the targeted specimens are sampled in real-time using a modified PerkinElmer UltraView LCI microscope. PMID:23165061

  4. A case of probable esomeprazole-induced transient liver injury in a pregnant woman with hyperemesis

    PubMed Central

    Thomas, Binny; Mohamed, Mahmoud; Al Hail, Moza; Awwad, Fatma Alzahra Y; Wahba, Ramy M; Hassan, Sabir B; Omar, Khalid; El Kassem, Wessam; Abdul Rouf, Palivalappila

    2016-01-01

    We report a case of 22-year-old primigravida presented to Women’s Hospital – Hamad Medical Corporation emergency with severe epigastric pain, nausea, and vomiting. On admission, she was dehydrated with remarkably worsening symptoms. Laboratory findings revealed significantly elevated liver enzymes with unknown etiology. Her past medical history showed an admission for nausea and vomiting 3 weeks previously and she was discharged on antiemetics, and esomeprazole for the first time. Due to the predominantly elevated liver enzymes, the clinical pharmacist discussed the possibility of esomeprazole-induced adverse effects and suggested to suspend esomeprazole based on the evidence from literature review. The liver enzymes showed a substantial improvement within days after the discontinuation of the drug; however, a rechallenge was not done since it could have adversely affected the mother or the fetus. Using the Naranjo Adverse Drug Reaction Probability scales, the adverse reaction due to esomeprazole was classified as “probably”. PMID:28008288

  5. Tumor-induced lymph node alterations detected by MRI lymphography using gadolinium nanoparticles.

    PubMed

    Partridge, S C; Kurland, B F; Liu, C-L; Ho, R J Y; Ruddell, A

    2015-10-26

    Contrast-enhanced MRI lymphography shows potential to identify alterations in lymph drainage through lymph nodes (LNs) in cancer and other diseases. MRI studies have typically used low molecular weight gadolinium contrast agents, however larger gadolinium-loaded nanoparticles possess characteristics that could improve the specificity and sensitivity of lymphography. The performance of three gadolinium contrast agents with different sizes and properties was compared by 3T MRI after subcutaneous injection. Mice bearing B16-F10 melanoma footpad tumors were imaged to assess tumor-induced alterations in lymph drainage through tumor-draining popliteal and inguinal LNs versus contralateral uninvolved drainage. Gadolinium lipid nanoparticles were able to identify tumor-induced alterations in contrast agent drainage into the popliteal LN, while lower molecular weight or albumin-binding gadolinium agents were less effective. All of the contrast agents distributed in foci around the cortex and medulla of tumor-draining popliteal LNs, while they were restricted to the cortex of non-draining LNs. Surprisingly, second-tier tumor-draining inguinal LNs exhibited reduced uptake, indicating that tumors can also divert LN drainage. These characteristics of tumor-induced lymph drainage could be useful for diagnosis of LN pathology in cancer and other diseases. The preferential uptake of nanoparticle contrasts into tumor-draining LNs could also allow selective targeting of therapies to tumor-draining LNs.

  6. Dexamethasone loaded nanoparticles exert protective effects against Cisplatin-induced hearing loss by systemic administration.

    PubMed

    Sun, Changling; Wang, Xueling; Chen, Dongye; Lin, Xin; Yu, Dehong; Wu, Hao

    2016-04-21

    Ototoxicity is one of the most important adverse effects of cisplatin chemotherapy. As a common treatment of acute sensorineural hearing loss, systemic administration of steroids was demonstrated ineffective against cisplatin-induced hearing loss (CIHL) in published studies. The current study aimed to evaluate the potential protective effect of dexamethasone (DEX) encapsulated in polyethyleneglycol-coated polylactic acid (PEG-PLA) nanoparticles (DEX-NPs) against cisplatin-induced hearing loss following systemic administration. DEX was fabricated into PEG-PLA nanoparticles using emulsion and evaporation technique as previously reported. DEX or DEX-NPs was administered intraperitoneally to guinea pigs 1h before cisplatin administration. Auditory brainstem response (ABR) threshold shifts were measured at four frequencies (4, 8, 16, and 24kHz) 1 day before and three days after cisplatin injection. Cochlear morphology was examined to evaluate inner ear injury induced by cisplatin exposure. A single dose of DEX-NPs 1h before cisplatin treatment resulted in a significant preservation of the functional and structural properties of the cochlea, which was equivalent to the effect of multidose (3 days) DEX injection. In contrast, no significant protective effect was observed by single dose injection of DEX. The results of histological examination of the cochleae were consistent with the functional measurements. In conclusion, a single dose DEX-NPs significantly attenuated cisplatin ototoxicity in guinea pigs after systemic administration at both histological and functional levels indicating the potential therapeutic benefits of these nanoparticles for enhancing the delivery of DEX in acute sensorineural hearing loss.

  7. Transient ectopic overexpression of agouti-signalling protein 1 (asip1) induces pigment anomalies in flatfish.

    PubMed

    Guillot, Raúl; Ceinos, Rosa Maria; Cal, Rosa; Rotllant, Josep; Cerdá-Reverter, José Miguel

    2012-01-01

    While flatfish in the wild exhibit a pronounced countershading of the dorso-ventral pigment pattern, malpigmentation is commonly observed in reared animals. In fish, the dorso-ventral pigment polarity is achieved because a melanization inhibition factor (MIF) inhibits melanoblast differentiation and encourages iridophore proliferation in the ventrum. A previous work of our group suggested that asip1 is the uncharacterized MIF concerned. In order to further support this hypothesis, we have characterized asip1 mRNAs in both turbot and sole and used deduced peptide alignments to analyze the evolutionary history of the agouti-family of peptides. The putative asip precursors have the characteristics of a secreted protein, displaying a putative hydrophobic signal. Processing of the potential signal peptide produces mature proteins that include an N-terminal region, a basic central domain with a high proportion of lysine residues as well as a proline-rich region that immediately precedes the C-terminal poly-cysteine domain. The expression of asip1 mRNA in the ventral area was significantly higher than in the dorsal region. Similarly, the expression of asip1 within the unpigmented patches in the dorsal skin of pseudoalbino fish was higher than in the pigmented dorsal regions but similar to those levels observed in the ventral skin. In addition, the injection/electroporation of asip1 capped mRNA in both species induced long term dorsal skin paling, suggesting the inhibition of the melanogenic pathways. The data suggest that fish asip1 is involved in the dorsal-ventral pigment patterning in adult fish, where it induces the regulatory asymmetry involved in precursor differentiation into mature chromatophore. Adult dorsal pseudoalbinism seems to be the consequence of the expression of normal developmental pathways in an inaccurate position that results in unbalanced asip1 production levels. This, in turn, generates a ventral-like differentiation environment in dorsal regions.

  8. Pumped storage system model and experimental investigations on S-induced issues during transients

    NASA Astrophysics Data System (ADS)

    Zeng, Wei; Yang, Jiandong; Hu, Jinhong

    2017-06-01

    Because of the important role of pumped storage stations in the peak regulation and frequency control of a power grid, pump turbines must rapidly switch between different operating modes, such as fast startup and load rejection. However, pump turbines go through the unstable S region in these transition processes, threatening the security and stability of the pumped storage station. This issue has mainly been investigated through numerical simulations, while field experiments generally involve high risks and are difficult to perform. Therefore, in this work, the model test method was employed to study S-induced security and stability issues for a pumped storage station in transition processes. First, a pumped storage system model was set up, including the piping system, model units, electrical control systems and measurement system. In this model, two pump turbines with different S-shaped characteristics were installed to determine the influence of S-shaped characteristics on transition processes. The model platform can be applied to simulate any hydraulic transition process that occurs in real power stations, such as load rejection, startup, and grid connection. On the experimental platform, the S-shaped characteristic curves were measured to be the basis of other experiments. Runaway experiments were performed to verify the impact of the S-shaped characteristics on the pump turbine runaway stability. Full load rejection tests were performed to validate the effect of the S-shaped characteristics on the water-hammer pressure. The condition of one pump turbine rejecting its load after another defined as one-after-another (OAA) load rejection was performed to validate the possibility of S-induced extreme draft tube pressure. Load rejection experiments with different guide vane closing schemes were performed to determine a suitable scheme to adapt the S-shaped characteristics. Through these experiments, the threats existing in the station were verified, the

  9. Iron oxide nanoparticles modulate lipopolysaccharide-induced inflammatory responses in primary human monocytes

    PubMed Central

    Grosse, Susann; Stenvik, Jørgen; Nilsen, Asbjørn M

    2016-01-01

    Co-stimulation of the immune system to more than one agent concomitantly is very common in real life, and considering the increasing use of engineered nanoparticles and nanomaterials, it is highly relevant to assess the ability of these materials to modulate key innate immune responses, which has not yet been studied in detail. We investigated the immunomodulatory effects of 10 nm and 30 nm iron oxide nanoparticles (IONPs) on primary human monocytes in the presence and absence of Toll-like receptor 4 agonist lipopolysaccharide (LPS). Prior to the cell studies, we characterized the physicochemical properties of the nanoparticles in cell culture medium and ensured that the nanoparticles were free from biological contamination. Cellular uptake of the IONPs in monocytes was assessed using transmission electron microscopy. Using enzyme-linked immunosorbent assay, we found that the IONPs per se did not induce the production of proinflammatory cytokines tumor necrosis factor-α, interleukin-6, and interleukin-1β. However, the IONPs had the ability to suppress LPS-induced nuclear factor kappa B activation and production of proinflammatory cytokines in primary human monocytes in an LPS and a particle dose-dependent manner. Using confocal microscopy and fluorescently labeled LPS, we showed that the effects correlated with impaired LPS internalization by monocytes in the presence of IONPs, which could be partly explained by LPS adsorption onto the nanoparticle surface. Additionally, the results from particle pretreatment experiments indicate that other cellular mechanisms might also play a role in the observed effects, which warrants further studies to elucidate the additional mechanisms underlying the capacity of IONPs to alter the reactivity of monocytes to LPS and to mount an appropriate cellular response. PMID:27695322

  10. Tumor cell apoptosis induced by nanoparticle conjugate in combination with radiation therapy.

    PubMed

    Wang, Li; Yang, Wensha; Read, Paul; Larner, James; Sheng, Ke

    2010-11-26

    Semiconductor nanoparticles conjugated to photosensitizers have been shown to increase tumor cell death with ionizing radiation but the mechanism, particularly the role of photodynamic therapy in the process, was unknown. We used a molecular probe to measure production of (1)O(2) to quantify the component of photodynamic cell-killing in an in vitro system. The intracellular distribution of the nanoparticle conjugate (NC) was determined by the co-localization of nanoparticles and the lysotracker. Induction of apoptosis was measured by the TUNEL assay and western blot analysis of the cleaved caspase-3. As a result, dose-dependent (1)O(2) production was observed with 48 nm NC after irradiating with 6 MV x-rays. A high geometrical coincidence between the fluorescence emission of the nanoparticle and lysotracker was observed using confocal microscopy. Finally, apoptosis, as indicated by the TUNEL stain and cleavage of the caspase-3, was observed in cells treated by both the NC and 6 Gy of radiation but not in cells treated with radiation alone. In conclusion, the cell death induced by the NC in combination with radiation is consistent with a supra-additive effect to radiation-or NC-alone-killing and is mediated by an NC-induced photodynamic therapy mechanism, which is distinctly different from that for radiation-killing alone. By providing a second distinct cell-killing mechanism, this nanoparticle conjugate has great promise as a targeted physical radiosensitizer aimed at overcoming radioresistant tumor clonogens or/and reducing normal tissue toxicity by using a lower ionizing radiation dose.

  11. Panthenol-stabilized cerium dioxide nanoparticles for cosmeceutic formulations against ROS-induced and UV-induced damage.

    PubMed

    Zholobak, N M; Shcherbakov, A B; Bogorad-Kobelska, A S; Ivanova, O S; Baranchikov, A Ye; Spivak, N Ya; Ivanov, V K

    2014-01-05

    A method of panthenol-stabilized cerium dioxide nanoparticles synthesis was developed and their effect on the survival rate of human epidermoid cancer cells HEp-2 and diploid epithelial swine testicular cell line (ST-cells) under oxidative stress conditions induced by hydrogen peroxide introduction and UV irradiation was studied. The results obtained indicate that the use of panthenol as a stabilizer supposedly provides a substantial increase in the efficiency of protection. The degree of protection is determined by panthenol-to-ceria molar ratio. The combination of panthenol and nano-ceria protects biological objects under study from reactive oxygen species (ROS) and UV-irradiation more effectively than individual panthenol or ceria. The protective action of panthenol-stabilized cerium dioxide nanoparticles depends strongly on their composition and the means of their application.

  12. Different Contribution of Redox-Sensitive Transient Receptor Potential Channels to Acetaminophen-Induced Death of Human Hepatoma Cell Line

    PubMed Central

    Badr, Heba; Kozai, Daisuke; Sakaguchi, Reiko; Numata, Tomohiro; Mori, Yasuo

    2016-01-01

    Acetaminophen (APAP) is a safe analgesic antipyretic drug at prescribed doses. Its overdose, however, can cause life-threatening liver damage. Though, involvement of oxidative stress is widely acknowledged in APAP-induced hepatocellular death, the mechanism of this increased oxidative stress and the associated alterations in Ca2+ homeostasis are still unclear. Among members of transient receptor potential (TRP) channels activated in response to oxidative stress, we here identify that redox-sensitive TRPV1, TRPC1, TRPM2, and TRPM7 channels underlie Ca2+ entry and downstream cellular damages induced by APAP in human hepatoma (HepG2) cells. Our data indicate that APAP treatment of HepG2 cells resulted in increased reactive oxygen species (ROS) production, glutathione (GSH) depletion, and Ca2+ entry leading to increased apoptotic cell death. These responses were significantly suppressed by pretreatment with the ROS scavengers N-acetyl-L-cysteine (NAC) and 4,5-dihydroxy-1,3-benzene disulfonic acid disodium salt monohydrate (Tiron), and also by preincubation of cells with the glutathione inducer Dimethylfumarate (DMF). TRP subtype-targeted pharmacological blockers and siRNAs strategy revealed that suppression of either TRPV1, TRPC1, TRPM2, or TRPM7 reduced APAP-induced ROS formation, Ca2+ influx, and cell death; the effects of suppression of TRPV1 or TRPC1, known to be activated by oxidative cysteine modifications, were stronger than those of TRPM2 or TRPM7. Interestingly, TRPV1 and TRPC1 were labeled by the cysteine-selective modification reagent, 5,5′-dithiobis (2-nitrobenzoic acid)-2biotin (DTNB-2Bio), and this was attenuated by pretreatment with APAP, suggesting that APAP and/or its oxidized metabolites act directly on the modification target cysteine residues of TRPV1 and TRPC1 proteins. In human liver tissue, TRPV1, TRPC1, TRPM2, and TRPM7 channels transcripts were localized mainly to hepatocytes and Kupffer cells. Our findings strongly suggest that APAP-induced

  13. Evolution of ion-induced nanoparticle arrays on GaAs surfaces

    NASA Astrophysics Data System (ADS)

    Kang, M.; Beskin, I.; Al-Heji, A. A.; Shende, O.; Huang, S.; Jeon, S.; Goldman, R. S.

    2014-05-01

    We have examined the evolution of irradiation-induced Ga nanoparticle (NP) arrays on GaAs surfaces. Focused-ion-beam irradiation of pre-patterned GaAs surfaces induces monotonic increases in the NP volume and aspect ratio up to a saturation ion dose, independent of NP location within the array. Beyond the saturation ion dose, the NP volume continues to increase monotonically while the NP aspect ratio decreases monotonically. In addition, the NP volumes (aspect ratios) are highest (lowest) for the corner NPs. We discuss the relative influences of bulk and surface diffusion on the evolution of Ga NP arrays.

  14. Defect induced ferromagnetism in undoped ZnO nanoparticles

    SciTech Connect

    Rainey, K.; Chess, J.; Eixenberger, J.; Tenne, D. A.; Hanna, C. B.; Punnoose, A.

    2014-05-07

    Undoped ZnO nanoparticles (NPs) with size ∼12 nm were produced using forced hydrolysis methods using diethylene glycol (DEG) [called ZnO-I] or denatured ethanol [called ZnO-II] as the reaction solvent; both using Zn acetate dehydrate as precursor. Both samples showed weak ferromagnetic behavior at 300 K with saturation magnetization M{sub s} = 0.077 ± 0.002 memu/g and 0.088 ± 0.013 memu/g for ZnO-I and ZnO-II samples, respectively. Fourier transform infrared (FTIR) spectra showed that ZnO-I nanocrystals had DEG fragments linked to their surface. Photoluminescence (PL) data showed a broad emission near 500 nm for ZnO-II which is absent in the ZnO-I samples, presumably due to the blocking of surface traps by the capping molecules. Intentional oxygen vacancies created in the ZnO-I NPs by annealing at 450 °C in flowing Ar gas gradually increased M{sub s} up to 90 min and x-ray photoelectron spectra (XPS) suggested that oxygen vacancies may have a key role in the observed changes in M{sub s}. Finally, PL spectra of ZnO showed the appearance of a blue/violet emission, attributed to Zn interstitials, whose intensity changes with annealing time, similar to the trend seen for M{sub s}. The observed variation in the magnetization of ZnO NP with increasing Ar annealing time seems to depend on the changes in the number of Zn interstitials and oxygen vacancies.

  15. Ionizing radiation-induced mutant frequencies increase transiently in male germ cells of older mice.

    PubMed

    Xu, Guogang; McMahan, C Alex; Hildreth, Kim; Garcia, Rebecca A; Herbert, Damon C; Walter, Christi A

    2012-05-15

    Spontaneous mutant frequency in the male germline increases with age, thereby increasing the risk of siring offspring with genetic disorders. In the present study we investigated the effect of age on ionizing radiation-induced male germline mutagenesis. lacI transgenic mice were treated with ionizing radiation at 4-, 15- and 26-month-old, and mutant frequencies were determined for pachytene spermatocytes and round spermatids at 15 days or 49 days after ionizing radiation treatment. Cells collected 15 days after treatment were derivatives of irradiated differentiating spermatogenic cells while cells collected 49 days later were derivatives of spermatogonial stem cells. The results showed that (1) spontaneous mutant frequency increased in spermatogenic cells recovered from nonirradiated old mice (26-months-old), particularly in the round spermatids; (2) mutant frequencies were significantly increased in round spermatids obtained from middle-aged mice (15-months-old) and old age mice (26-months-old) at 15 and 49 days after irradiation compared to the sham-treated old mice; and (3) pachytene spermatocytes obtained from 15- or 26-month-old mice displayed a significantly increased mutant frequency at 15 days post irradiation. This study indicates that age modulates the mutagenic response to ionizing radiation in the male germline.

  16. Pressure-induced evaporation dynamics of gold nanoparticles on oxide substrate.

    PubMed

    Meng, Gang; Yanagida, Takeshi; Kanai, Masaki; Suzuki, Masaru; Nagashima, Kazuki; Xu, Bo; Zhuge, Fuwei; Klamchuen, Annop; He, Yong; Rahong, Sakon; Kai, Shoichi; Kawai, Tomoji

    2013-01-01

    Here we report thermal evaporation dynamics of Au nanoparticles on single crystal oxide substrates, including MgO, SrTiO(3), and Al(2)O(3). The size reduction rate of Au nanoparticles via thermal treatments is strongly dependent on not only temperature but also pressure. Lowering the pressure of inert Ar gas from 10(5) to 10 Pa increases the size reduction rate over 30 times in the temperature range 800 °C-950 °C. The temperature dependence is solely due to the variation of saturated vapor pressure of Au, whereas the pressure dependence of the surrounding inert gas can be interpreted in terms of a pressure dependence on a gas-phase diffusion of evaporated Au atoms into the surroundings. We present a simplified model to explain an evaporation dynamics, which well describes the pressure dependence on a size reduction rate of Au nanoparticles. By utilizing this useful pressure-induced evaporation dynamics, we succeeded in manipulating a size reduction of Au nanoparticle arrays down to -10 nm diameter range from -300 nm initial size by programming sequentially a surrounding pressure.

  17. Aggregation-induced emissive nanoparticles for fluorescence signaling in a low cost paper-based immunoassay.

    PubMed

    Engels, Jan F; Roose, Jesse; Zhai, Demi Shuang; Yip, Ka Man; Lee, Mei Suet; Tang, Ben Zhong; Renneberg, Reinhard

    2016-07-01

    Low cost paper based immunoassays are receiving interest due to their fast performance and small amounts of biomolecules needed for developing an immunoassay complex. In this work aggregation-induced emissive (AIE) nanoparticles, obtained from a diastereoisomeric mixture of 1,2-di-(4-hydroxyphenyl)-1,2-diphenylethene (TPEDH) in a one-step top-down method, are characterized through Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Zeta potential. By measuring the Zeta potential before and after labeling the nanoparticles with antibodies we demonstrate that the colloidal system is stable in a wide pH-range. The AIE-active nanoparticles are deposited on chitosan and glutaraldehyde modified paper pads overcoming the common aggregation-caused quenching (ACQ) effect. Analyte concentrations from 1000ng and below are applied in a model immunocomplex using Goat anti-Rabbit IgG and Rabbit IgG. In the range of 7.81ng-250ng, linear trends with a high R(2) are observed, which leads to a strong increase of the blue fluorescence from the TPEDH nanoparticles.

  18. Laser wavelength effect on laser-induced photo-thermal sintering of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Paeng, Dongwoo; Yeo, Junyeob; Lee, Daeho; Moon, Seung-Jae; Grigoropoulos, Costas P.

    2015-09-01

    This work is concerned with the laser wavelength effect on the electrical properties and surface morphology of laser-sintered nanoparticle thin films. Silver nanoparticle thin films spin-coated on soda lime glass substrates were irradiated with lasers of three different wavelengths (near ultraviolet 405 nm, green 514.5 nm, near infrared 817 nm) at varied laser intensities and scanning speeds. Scanning electron microscopy images and ex situ resistivity measurements show that the photo-thermal sintering alters significantly the film surface morphology and electrical properties, depending on the processing parameters (laser wavelength, laser intensities and scanning speed). While the optical response of the material is determined largely by the processing laser wavelength, the laser beam intensity and scanning speed regulate the induced temperature field. Examination of the optical properties of as-deposited silver nanoparticle thin film in conjunction with scanning electron microscopy images taken from the laser-sintered lines helps elucidate how the processing laser wavelength modulates the optical response of silver nanoparticle thin film and therefore affects the thermal response.

  19. Novel self-micellizing anticancer lipid nanoparticles induce cell death of colorectal cancer cells.

    PubMed

    Sundaramoorthy, Pasupathi; Baskaran, Rengarajan; Mishra, Siddhartha Kumar; Jeong, Keun-Yeong; Oh, Seung Hyun; Kyu Yoo, Bong; Kim, Hwan Mook

    2015-11-01

    In the present study, we developed a novel drug-like self-micellizing anticancer lipid (SMAL), and investigated its anticancer activity and effects on cell death pathways in human colorectal cancer (CRC) cell lines. Three self-assembled nanoparticles were prepared, namely, SMAL102 (lauramide derivative), SMAL104 (palmitamide derivative), and SMAL108 (stearamide derivative) by a thin-film hydration technique, and were characterized for physicochemical and biological parameters. SMAL102 were nanosized (160.23 ± 8.11 nm) with uniform spherical shape, while SMAL104 and SMAL108 did not form spherical shape but formed large size nanoparticles and irregular in shape. Importantly, SMAL102 showed a cytotoxic effect towards CRC cell lines (HCT116 and HT-29), and less toxicity to a normal colon fibroblast cell line (CCD-18Co). Conversely, SMAL104 and SMAL108 did not have an anti-proliferative effect on CRC cell lines. SMAL102 nanoparticles were actively taken up by CRC cell lines, localized in the cell membrane, and exhibited remarkable cytotoxicity in a concentration-dependent manner. The normal colon cell line showed significantly less cellular uptake and non-cytotoxicity as compared with the CRC cell lines. SMAL102 nanoparticles induced caspase-3, caspase-9, and PARP cleavage in HT-29 cells, indicating the induction of apoptosis; whereas LC3B was activated in HCT116 cells, indicating autophagy-induced cell death. Collectively, these results demonstrate that SMAL102 induced cell death via activation of apoptosis and autophagy in CRC cell lines. The present study could be a pioneer for further preclinical and clinical development of such compounds.

  20. Importance of the HIF pathway in cobalt nanoparticle-induced cytotoxicity and inflammation in human macrophages.

    PubMed

    Nyga, Agata; Hart, Alister; Tetley, Teresa D

    2015-01-01

    Recent, unexpected high failure rates of metal-on-metal hip implants have reintroduced the issue of cobalt toxicity. An adverse reaction to cobalt ions and cobalt-induced lung injury occurs during environmental exposure and is now strictly controlled. Currently adverse reaction occurs to cobalt nanoparticles during wear and tear of metal-on-metal hip implants of which the underlying mechanism is not fully understood. The putative role of the hypoxia-inducible factor (HIF) pathway in the mechanism of cobalt nanoparticle (Co-NPs) toxicity was examined using the U937 cell line, human alveolar macrophages and monocyte-derived macrophages. Co-NPs (5-20 μg/ml)-induced cytotoxicity (viability ranged from 75% to <20% of control, respectively) and reactive oxygen species (ROS), whereas a comparable concentration of cobalt ions (Co(II); up to 350 μM) did not. Co-NPs induced HIF-1α stabilization. Addition of ascorbic acid (100 µM) and glutathione (1 mM) both prevented the increased ROS. However, only treatment with ascorbic acid reduced HIF-1α levels and prevented cell death, indicating that a ROS-independent pathway is involved in Co-NPs-induced cytotoxicity. Replenishing intracellular ascorbate, which is crucial in preventing HIF pathway activation, modified Co-induced HIF target gene expression and the inflammatory response, by decreasing interleukin-1 beta (IL-1β) mRNA and protein expression. Addition of glutathione had no effect on Co-NPs-induced HIF target gene expression or inflammatory response. Thus, Co-NPs induce the HIF pathway by depleting intracellular ascorbate, leading to HIF stabilization and pathway activation. This suggests a strong, ROS-independent role for HIF activation in Co-NPs-induced cytotoxicity and a possible role for HIF in metal-on-metal hip implant pathology.

  1. Transient changes in bacterioplankton communities induced by the submarine volcanic eruption of El Hierro (Canary Islands).

    PubMed

    Ferrera, Isabel; Arístegui, Javier; González, José M; Montero, María F; Fraile-Nuez, Eugenio; Gasol, Josep M

    2015-01-01

    The submarine volcanic eruption occurring near El Hierro (Canary Islands) in October 2011 provided a unique opportunity to determine the effects of such events on the microbial populations of the surrounding waters. The birth of a new underwater volcano produced a large plume of vent material detectable from space that led to abrupt changes in the physical-chemical properties of the water column. We combined flow cytometry and 454-pyrosequencing of 16S rRNA gene amplicons (V1-V3 regions for Bacteria and V3-V5 for Archaea) to monitor the area around the volcano through the eruptive and post-eruptive phases (November 2011 to April 2012). Flow cytometric analyses revealed higher abundance and relative activity (expressed as a percentage of high-nucleic acid content cells) of heterotrophic prokaryotes during the eruptive process as compared to post-eruptive stages. Changes observed in populations detectable by flow cytometry were more evident at depths closer to the volcano (~70-200 m), coinciding also with oxygen depletion. Alpha-diversity analyses revealed that species richness (Chao1 index) decreased during the eruptive phase; however, no dramatic changes in community composition were observed. The most abundant taxa during the eruptive phase were similar to those in the post-eruptive stages and to those typically prevalent in oceanic bacterioplankton communities (i.e. the alphaproteobacterial SAR11 group, the Flavobacteriia class of the Bacteroidetes and certain groups of Gammaproteobacteria). Yet, although at low abundance, we also detected the presence of taxa not typically found in bacterioplankton communities such as the Epsilonproteobacteria and members of the candidate division ZB3, particularly during the eruptive stage. These groups are often associated with deep-sea hydrothermal vents or sulfur-rich springs. Both cytometric and sequence analyses showed that once the eruption ceased, evidences of the volcano-induced changes were no longer observed.

  2. Seismically induced pressure transients at geothermal reservoirs in the eastern Marmara region

    NASA Astrophysics Data System (ADS)

    Woith, Heiko; Wang, Rongjiang; Caka, Deniz; Irmak, T. Serkan; Tunc, Berna; Luehr, Birger-G.; Baris, Serif

    2014-05-01

    The potential role of fluids in processes related to the triggering of earthquakes and volcanic eruptions is frequently emphasized. Here, we focus on the response of hydrogeological systems to earthquakes, specifically on seismically induced pore-pressure variations in geothermal areas located in the eastern Marmara region. At a 500 m deep artesian geothermal well the pressure is continuously being monitored at a sampling rate of 100 Hz. A seismometer is co-located close to the well-head and the data are recorded by the same digitizer. Hydro-seismograms were recorded in relation to local and distant earthquakes. The ML=5.2 Manyas earthquake which occurred on 20 October 2006 at a distance of 77 km led to a dynamic response of the pore pressure of the order of 4 mbar triggered upon the arrival of the S-wave. Four days later, the ML=5.2 Gemlik earthquake at a distance of 20 km led to a dynamic pore pressure response of the order of 15 mbar triggered upon the arrival of the P-wave. In both cases the peak amplitude of the ground velocity was about 2 mm/s. Weak oscillations of the pore pressure were observed during the passage of surface waves generated by remote earthquakes at distances of up to 9,000 km. Additionally to the dynamic response, a small persistent pressure increase of 1 and 2 mbar had been recorded after both local earthquakes. According to preliminary results, the observed pressure increase is opposite to the static pressure decrease predicted by Okada's model. At the present stage we conclude that the response of the Armutlu geothermal system to earthquakes is likely caused by a dynamic interaction of passing seismic waves (P-, S-, and surface waves) with the fluid reservoir in case a threshold of the ground shaking is exceeded.

  3. Transient Changes in Bacterioplankton Communities Induced by the Submarine Volcanic Eruption of El Hierro (Canary Islands)

    PubMed Central

    Ferrera, Isabel; Arístegui, Javier; González, José M.; Montero, María F.; Fraile-Nuez, Eugenio; Gasol, Josep M.

    2015-01-01

    The submarine volcanic eruption occurring near El Hierro (Canary Islands) in October 2011 provided a unique opportunity to determine the effects of such events on the microbial populations of the surrounding waters. The birth of a new underwater volcano produced a large plume of vent material detectable from space that led to abrupt changes in the physical-chemical properties of the water column. We combined flow cytometry and 454-pyrosequencing of 16S rRNA gene amplicons (V1–V3 regions for Bacteria and V3–V5 for Archaea) to monitor the area around the volcano through the eruptive and post-eruptive phases (November 2011 to April 2012). Flow cytometric analyses revealed higher abundance and relative activity (expressed as a percentage of high-nucleic acid content cells) of heterotrophic prokaryotes during the eruptive process as compared to post-eruptive stages. Changes observed in populations detectable by flow cytometry were more evident at depths closer to the volcano (~70–200 m), coinciding also with oxygen depletion. Alpha-diversity analyses revealed that species richness (Chao1 index) decreased during the eruptive phase; however, no dramatic changes in community composition were observed. The most abundant taxa during the eruptive phase were similar to those in the post-eruptive stages and to those typically prevalent in oceanic bacterioplankton communities (i.e. the alphaproteobacterial SAR11 group, the Flavobacteriia class of the Bacteroidetes and certain groups of Gammaproteobacteria). Yet, although at low abundance, we also detected the presence of taxa not typically found in bacterioplankton communities such as the Epsilonproteobacteria and members of the candidate division ZB3, particularly during the eruptive stage. These groups are often associated with deep-sea hydrothermal vents or sulfur-rich springs. Both cytometric and sequence analyses showed that once the eruption ceased, evidences of the volcano-induced changes were no longer observed

  4. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  5. Imaging transient melting of a nanocrystal using an X-ray laser

    SciTech Connect

    Clark, Jesse N.; Beitra, Loren; Xiong, Gang; Fritz, David M.; Lemke, Henrik T.; Zhu, Diling; Chollet, Matthieu; Williams, Garth J.; Messerschmidt, Marc M.; Abbey, Brian; Harder, Ross J.; Korsunsky, Alexander M.; Wark, Justin S.; Reis, David A.; Robinson, Ian K.

    2015-06-01

    There is a fundamental interest in studying photoinduced dynam- ics in nanoparticles and nanostructures as it provides insight into their mechanical and thermal properties out of equilibrium and during phase transitions. Nanoparticles can display significantly different properties from the bulk, which is due to the interplay between their size, morphology, crystallinity, defect concentra- tion, and surface properties. Particularly interesting scenarios arise when nanoparticles undergo phase transitions, such as melting induced by an optical laser. Current theoretical evidence suggests that nanoparticles can undergo reversible nonhomogenous melt- ing with the formation of a core-shell structure consisting of a liquid outer layer. To date, studies from ensembles of nanoparticles have tentatively suggested that such mechanisms are present. Here we demonstrate imaging transient melting and softening of the acoustic phonon modes of an individual gold nanocrystal, using an X-ray free electron laser. The results demonstrate that the transient melting is reversible and nonhomogenous, consistent with a core-shell model of melting. The results have implications for understanding transient processes in nanoparticles and determining their elastic properties as they undergo phase transitio

  6. Prior TLR5 induction in human T cells results in a transient potentiation of subsequent TCR-induced cytokine production.

    PubMed

    Tremblay, Mikaela M; Bilal, Mahmood Y; Houtman, Jon C D

    2014-02-01

    Activation of TLRs by components required for pathogen viability results in increased inflammation and an enhanced immune response to infection. Unlike their effects on other immune cells, TLR activation in the absence of T cell antigen receptor (TCR) induction has little effect on T cell activity. Instead, the simultaneous induction of TLR and TCR results in increased cytokine release compared to TCR treatment alone. Thus, the current model states that TLRs alter T cell function only if activated at the same time as the TCR. In this study, we tested the novel hypothesis that prior TLR induction can also alter TCR-mediated functions. We found that human T cells responded to ligands for TLR2 and TLR5. However, only prior TLR5 induction potentiated subsequent TCR-mediated cytokine production in human T cells. This response required at least 24h of TLR5 induction and lasted for approximately 24-36h after removal of a TLR5 ligand. Interestingly, prior TLR5 induction enhanced TCR-mediated activation of Akt without increasing Lck, LAT or ERK kinase phosphorylation. Together, our studies show that TLR5 induction leads to a transient increase in the sensitivity of T cells to TCR stimulation by selectively enhancing TCR-mediated Akt function, highlighting that timeframe when TLR5 can potentiate TCR-induced downstream functions are significantly longer that previously appreciated.

  7. Ligation and quaternary structure induced changes in the heme pocket of hemoglobin: a transient resonance Raman study.

    PubMed

    Friedman, J M; Stepnoski, R A; Stavola, M; Ondrias, M R; Cone, R L

    1982-04-27

    The extent to which ligation and quaternary structure modify the heme-heme pocket configuration is determined by generating and analyzing transient resonance Raman spectra from various photolyzed and partially photolyzed hemoglobins (Hb). From small frequently shifts in Raman band I (approximately 1355 cm-1) it is determined that ligation induces a configurational change about the heme. The extent to which ligation modifies the heme pocket is influenced by the quaternary structure. With respect to the structural parameter responsible for variations in the pi orbital electron density of the porphyrin, the degree of alteration of the heme pocket configuration relative to deoxy-Hb(T) follows the sequence: liganded Hb(R) greater than liganded Hb(R) + IHP greater than liganded Hb(T) [alpha chain greater than beta chain] greater than deoxy-Hb(R). This progression of configurations also forms a sequence with respect to the "retentiveness" of the heme pocket as reflected in the ligand dynamics associated with geminate recombination. The results indicate that the heme-heme pocket of the R-state Hb's, relative to those of the T-state species, favors ligand retention in a dynamic, as well as thermodynamic, sense. The analysis of these and other related data implicates a ligation and quaternary structure modulated electronic and/or electrostatic interaction between the pi system of the porphyrin and the surrounding heme pocket as the basis for this variation in ligand dynamics as well as for the energetics of cooperativity.

  8. Transient luminescence induced by electrical refilling of charge carrier traps of dislocation network at hydrophilically bonded Si wafers interface

    SciTech Connect

    Bondarenko, Anton; Vyvenko, Oleg

    2014-02-21

    Dislocation network (DN) at hydrophilically bonded Si wafers interface is placed in space charge region (SCR) of a Schottky diode at a depth of about 150 nm from Schottky electrode for simultaneous investigation of its electrical and luminescent properties. Our recently proposed pulsed traps refilling enhanced luminescence (Pulsed-TREL) technique based on the effect of transient luminescence induced by refilling of charge carrier traps with electrical pulses is further developed and used as a tool to establish DN energy levels responsible for D1 band of dislocation-related luminescence in Si (DRL). In present work we do theoretical analysis and simulation of traps refilling kinetics dependence on refilling pulse magnitude (Vp) in two levels model: shallow and deep. The influence of initial charge state of deep level on shallow level occupation-Vp dependence is discussed. Characteristic features predicted by simulations are used for Pulsed-TREL experimental results interpretation. We conclude that only shallow (∼0.1 eV from conduction and valence band) energetic levels in the band gap participate in D1 DRL.

  9. Characterization of β-cell plasticity mechanisms induced in mice by a transient source of exogenous insulin.

    PubMed

    Nollevaux, M-C; Rahier, J; Marchandise, J; Thurion, P; Godecharles, S; Van den Steen, G; Jamart, J; Sempoux, C; Jacquemin, P; Guiot, Y

    2013-04-01

    β-Cell plasticity governs the adjustment of β-cell mass and function to ensure normoglycemia. The study of how β-cell mass is controlled and the identification of alternative sources of β-cells are active fields of research. β-Cell plasticity has been implicated in numerous physiological and pathological conditions. We developed a mice model in which we induced major β-cell mass atrophy by implanting insulin pellets (IPI) for 7 or 10 days. The implants were then removed (IPR) to observe the timing and characteristics of β-cell regeneration in parallel to changes in glycemia. Following IPR, the endocrine mass was reduced by 60% at day 7 and by 75% at day 10, and transient hyperglycemia was observed, which resolved within 1 wk. Five days after IPR, enhanced β-cell proliferation and an increased frequency of small islets were observed in 7-day IPI mice. β-Cell mass was fully restored after an additional 2 days. For the 10-day IPI group, β-cell and endocrine mass were no longer significantly different from those of the control group at 2 wk post-IPR. Furthermore, real-time quantitative PCR analysis of endocrine structures isolated by laser capture microdissection indicated sequentially enhanced expression of the pancreatic transcription factors β(2)/NeuroD and Pdx-1 post-IPR. Thus, our data suggest this mouse model of β-cell plasticity not only relies on replication but also involves enhanced cell differentiation plasticity.

  10. Acetaldehyde targets superoxide dismutase 2 in liver cancer cells inducing transient enzyme impairment and a rapid transcriptional recovery.

    PubMed

    Clavijo-Cornejo, Denise; Gutiérrez-Carrera, Mario; Palestino-Domínguez, Mayrel; Dominguez-Perez, Mayra; Nuño, Natalia; Souza, Veronica; Miranda, Roxana U; Kershenobich, David; Gutiérrez-Ruiz, Ma Concepción; Bucio, Leticia; Gómez-Quiroz, Luis E

    2014-07-01

    Alcohol is undoubtedly, the main toxic agent that people consume by recreation and the abuse is associated with liver damage, mainly by the overproduction of reactive oxygen species and the toxic effects of its first metabolite acetaldehyde. It is known that acetaldehyde targets mitochondria inducing redox imbalance and oxidative stress. Mitochondrial superoxide dismutase transforms superoxide radical into hydrogen peroxide, which in addition, is transformed in water by other enzymes. In the present study we demonstrate that acetaldehyde transiently impairs SOD2 activity in HepG2 cells, the decrease in the enzyme activity was associated to a reduction in the protein content, which was rapidly recovered, to basal values, by synthesis de novo in a mechanism mediated by NF-κB and PKC. The SOD2 impairment was not associated with adduct formation. The recovery on SOD2 activity in HepG2 cells can represent survival advantage for cancer cells, the results shown that SOD2 could be considered a therapeutic target in liver cancer.

  11. Tungsten Carbide-Cobalt Nanoparticles Induce Reactive Oxygen Species, AKT, ERK, AP-1, NF-κB, VEGF, and Angiogenesis.

    PubMed

    Liu, Ling-Zhi; Ding, Min; Zheng, Jenny Z; Zhu, Yingxue; Fenderson, Bruce A; Li, Bingyun; Yu, Jing J; Jiang, Bing-Hua

    2015-07-01

    Powder mixtures of tungsten carbide and metallic cobalt (WC-Co) are widely used in various products. Nanoparticles are engineered structures with at least one dimension of 100 nm or smaller. WC-Co is known to be associated with lung injury and diseases. Angiogenesis is a key process during vasculature, carcinogenesis, recovery of injury, and inflammatory diseases. However, the cellular effects of WC-Co nanoparticles on angiogenesis remain to be elucidated. In this study, we investigated angiogenic response and relative mechanisms after exposure to WC-Co nanoparticles. Our results showed that WC-Co nanoparticles at 5 μg/cm(2) induced ROS production which activated AKT and ERK1/2 signaling pathways in lung epithelial cells by reactive oxygen species (ROS) staining and immunoblotting; WC-Co treatment also increased transcriptional activation of AP-1, NF-κB, and VEGF by reporter assay. Further studies demonstrated that ROS are upstream molecules of AKT and ERK signaling pathways; the activation of AP-1, NF-κB, and VEGF was through ROS generation, AKT and ERK1/2 activation. In addition, WC-Co nanoparticles affected the cells to induce angiogenesis by chicken chorioallantoic membrane (CAM) assay. These results illustrate that exposure to WC-Co nanoparticles induces angiogenic response by activating ROS, AKT, and ERK1/2 signaling pathways and the downstream molecules and elucidate the potential molecular mechanisms during this process. This information may be useful for preventing potential damage from nanoparticle exposure in the future.

  12. Marek's disease virus-induced transient paralysis is associated with cytokine gene expression in the nervous system.

    PubMed

    Abdul-Careem, M F; Hunter, B D; Sarson, A J; Mayameei, A; Zhou, H; Sharif, S

    2006-01-01

    Marek's disease (MD)-associated transient paralysis (TP) was experimentally induced in chickens by intraperitoneal inoculation of RB1B strain of Marek's disease virus (MDV). Between 7 and 11 days post-infection (d.p.i.), neck and limb paralysis was observed in 18% of infected chickens, which was associated with various degrees of edema, vacuolation, perivascular cuffing of mononuclear cells, and glial cell infiltration mainly in the cerebrum, cerebellum, and brain stem. The chickens that were infected but did not progress to develop TP until 12 d.p.i. also had similar lesions suggestive of encephalitis in the cerebrum, cerebellum, and brain stem. Chickens infected with MDV had more interleukin (IL)-6, IL-12, and interferon (IFN)-gamma in their brain tissues compared to uninfected chickens. Moreover, IL-18 was significantly increased in brain tissues of birds showing clinical signs of TP compared to uninfected birds. Importantly, the expression of IL-6, IL-18, and IFN- gamma in brain tissues of MDV-infected chickens with signs of TP was significantly increased compared to that in asymptomatic MDV-infected birds. MDV genome load in the brain of chickens showing clinical signs of TP was higher than that in asymptomatic MDV-infected chickens but was not statistically significant. The lesions in the cervical, thoracic, and lumbar spinal cord segments in MDVinfected chickens were characterized mainly by perivascular cuffing of mononuclear cells irrespective of the group. The expression of mRNA for IL-18 and IFN-gamma genes was not significantly different in spinal cord tissues of chickens with TP compared to clinically normal, MDV-infected and noninfected chickens. These results suggest possible underlying immunologic mechanisms for MDV-induced TP.

  13. Deep level transient spectroscopy study of particle irradiation induced defects in n-6H-SiC

    NASA Astrophysics Data System (ADS)

    Chen, X. D.; Gong, M.; Fung, S.; Beling, C. D.; Ling, C. C.

    2004-03-01

    Neutron and electron irradiation induced deep level defects in n-type 6H-SiC have been investigated using deep level transient spectroscopy (DLTS) combined with annealing experiments. Deep levels ED1, E1/E2, Ei, and Z1/Z2 were observed in n-type 6H-SiC material irradiated with neutron. Thermal annealing studies of these deep levels revealed that ED1 and Ei annealed at a temperature below 350^oC, Z1/Z2 levels annealed out at 900^oC, while the intensity of the E1/E2 peaks increased with annealing temperature, reached a maximum at about 500-750^oC, and finally annealed out at 1400^oC. Upon further annealing at 1600^oC, four deep levels labeled NE1 at EC-0.44eV, NE2 EC-0.53eV, NE3 EC-0.64eV, and NE4 EC-0.68eV are produced. Ionization energies of these levels are similar to E1/E2 and Z1/Z2 respectively, but their capture cross sections are different. Samples were irradiated with electrons with different energies ranging from 0.2MeV to 1.7MeV. No deep level was detected in samples irradiated with 0.2MeV electron and deep levels ED1, E1/E2, and Ei were induced with electron energy larger than 0.3MeV.

  14. Interface interaction induced ultra-dense nanoparticles assemblies.

    PubMed

    Song, Yujun; Wang, Yan; Li, Bin Bin; Fernandes, Carlos; Ruda, Harry E

    2013-08-07

    We demonstrate a simple and clean physical methodology for fabricating such nanoparticle assemblies (dense arrays and/or dendrites) related to the interfacial interaction between the constructed materials and the anodized aluminum oxide (AAO) porous templates. The interfacial interaction can be regulated by the surface tension of the constructed materials and the AAO membrane, and the AAO-template structure, such as pore size, membrane thickness and surface morphologies. Depending on the interfacial interaction between the constructed materials and the AAO templates, NP arrays with mean particle diameters from 3.8 ± 1.0 nm to 12.5 ± 2.9 nm, mean inter-edge spacings from 3.5 ± 1.4 nm to 7.9 ± 3.4 nm and areal densities from 5.6 × 10(11) NPs per cm(2) to 1.5 × 10(12) NPs per cm(2) are fabricated over large areas (currently ~2 cm × 3 cm). The fabrication process includes firstly thermal evaporation of metal layers no more than 10 nm thick on the pre-coated Si wafer by AAO templates with a thickness of less than 150 nm and mean pore sizes no more than 12 nm, and then removal of the AAO templates. The NP arrays can be stable for hours at a temperature slightly below the melting point of the constructed materials (e.g., ~800 °C for Au NPs for 4 hours) with little change in size and inter-particle separation. Using one of them (e.g., 11.8 nm Au NPs) as growth-oriented catalysts, ultra-thin (12.1 ± 2.3 nm) dense nanowires can be conveniently obtained. Furthermore, dendrite superstructures can be generated easily from eutectic alloy NPs with diameters of ~10 nm pre-formed by thermal evaporation of metal layers more than 20 nm thick on surface-patterned thick AAO templates (e.g., 500 nm). The resulting dendrites, dense arrays and other superstructures (i.e., nanorods and nanowires) formed using NP arrays as catalysts, should have broad applications in catalysis, information technology, photovoltaics and biomedical engineering.

  15. Transient expression of specific Cotesia plutellae bracoviral segments induces prolonged larval development of the diamondback moth, Plutella xylostella.

    PubMed

    Kwon, Bowon; Song, Seongbaeck; Choi, Jae Young; Je, Yeon Ho; Kim, Yonggyun

    2010-06-01

    A polydnavirus, Cotesia plutellae bracovirus (CpBV), possesses a segmented and dispersed genome that is located on chromosome(s) of its symbiotic endoparasitic wasp, C. plutellae. When the host wasp parasitizes larvae of the diamondback moth, Plutella xylostella, at least 27 viral genome segments are delivered to the parasitized host along with the wasp egg. The parasitized P. xylostella exhibits significant immunosuppression and a prolonged larval development. Parasitized larvae take about 2 days longer than nonparasitized larvae to develop until the wandering stage of the final larval instar, and die after egress of the full grown wasp larvae. Developmental analysis using juvenile hormone and ecdysteroid analogs suggests that altering endocrine signals could induce the retardation of larval developmental rate in P. xylostella. In this study we used a transient expression technique to micro-inject individual CpBV genome segments, and tested their ability to induce delayed larval development of P. xylostella. We demonstrated that a CpBV segment was able to express its own encoded genes when it was injected into nonparasitized larvae, in which the expression patterns of the segment genes were similar to those in the larvae parasitized by C. plutellae. Twenty three CpBV genome segments were individually cloned and injected into the second instar larvae of P. xylostella and their effects assessed by measuring the time taken for host development to the cocooning stage. Three CpBV genome segments markedly interfered with the host larval development. When the putative genes of these segments were analyzed, it was found that they did not share any common genes. Among these segments able to delay host development, segment S27 was predicted to encode seven protein tyrosine phosphatases (CpBV-PTPs), some of which were mutated by insertional inactivation with transposons, while other encoded gene expressions were unaffected. The mutant segments were unable to induce prolonged

  16. Cell-cycle-dependent Ca(2+) transients in human induced pluripotent stem cells revealed by a simultaneous imaging of cell nuclei and intracellular Ca(2+) level.

    PubMed

    Shimba, Kenta; Iida, Shoko; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2016-09-12

    Cell cycle phase and [Ca(2+)]i are key determinants of self-renewal and differentiation in pluripotent stem cells. However, little is known about their relationship in human pluripotent stem cells owing to the lack of an effective method. Here, we applied an imaging-based approach for evaluating the relationship between the cell cycle and Ca(2+) transients in human induced pluripotent stem (iPS) cells. Ca imaging and DNA staining was simultaneously performed at the same site. Then, individual cells were recognized and the cell cycle phase was estimated from the image of nuclei. We found that 18 ± 4% of human iPS cells exhibited spontaneous Ca(2+) transients and their inter-transient interval was 119 ± 19 s. Ca wave events were observed in 64% of the sample and the [Ca(2+)]i elevation propagated among 47 ± 30 cells with a duration of 57 ± 22 s. With the imaging-based approach, we demonstrated that the ratio of cells exhibiting Ca(2+) transients significantly decreased during cell cycle progression, suggesting that the relationship previously described in mouse cells holds true in the human context as well. These results suggest that our method is suitable for evaluating Ca(2+) transients, the cell cycle phase, and their relationship with densely cultured cells.

  17. Entropic attraction: Polymer compaction and expansion induced by nano-particles in confinement.

    PubMed

    Liao, Guo-Jun; Chien, Fan-Tso; Luzhbin, Dmytro; Chen, Yeng-Long

    2015-05-07

    We investigated nanoparticle (NP)-induced coil-to-globule transition of a semi-flexible polymer in a confined suspension of ideal NP using Langevin dynamics. DNA molecules are often found to be highly compact, bound with oppositely charged proteins in a crowded environment within cells and viruses. Recent studies found that high concentration of electrostatically neutral NP also condenses DNA due to entropically induced depletion attraction between DNA segments. Langevin dynamics simulations with a semi-flexible chain under strong confinement were performed to investigate the competition between NP-induced monomer-monomer and monomer-wall attraction under different confinement heights and NP volume fractions. We found that whether NP induce polymer segments to adsorb to the walls and swell or to attract one another and compact strongly depends on the relative strength of the monomer-wall and the NP-wall interactions.

  18. Interface interaction induced ultra-dense nanoparticles assemblies

    NASA Astrophysics Data System (ADS)

    Song, Yujun; Wang, Yan; Li, Bin Bin; Fernandes, Carlos; Ruda, Harry E.

    2013-07-01

    We demonstrate a simple and clean physical methodology for fabricating such nanoparticle assemblies (dense arrays and/or dendrites) related to the interfacial interaction between the constructed materials and the anodized aluminum oxide (AAO) porous templates. The interfacial interaction can be regulated by the surface tension of the constructed materials and the AAO membrane, and the AAO-template structure, such as pore size, membrane thickness and surface morphologies. Depending on the interfacial interaction between the constructed materials and the AAO templates, NP arrays with mean particle diameters from 3.8 +/- 1.0 nm to 12.5 +/- 2.9 nm, mean inter-edge spacings from 3.5 +/- 1.4 nm to 7.9 +/- 3.4 nm and areal densities from 5.6 × 1011 NPs per cm2 to 1.5 × 1012 NPs per cm2 are fabricated over large areas (currently ~2 cm × 3 cm). The fabrication process includes firstly thermal evaporation of metal layers no more than 10 nm thick on the pre-coated Si wafer by AAO templates with a thickness of less than 150 nm and mean pore sizes no more than 12 nm, and then removal of the AAO templates. The NP arrays can be stable for hours at a temperature slightly below the melting point of the constructed materials (e.g., ~800 °C for Au NPs for 4 hours) with little change in size and inter-particle separation. Using one of them (e.g., 11.8 nm Au NPs) as growth-oriented catalysts, ultra-thin (12.1 +/- 2.3 nm) dense nanowires can be conveniently obtained. Furthermore, dendrite superstructures can be generated easily from eutectic alloy NPs with diameters of ~10 nm pre-formed by thermal evaporation of metal layers more than 20 nm thick on surface-patterned thick AAO templates (e.g., 500 nm). The resulting dendrites, dense arrays and other superstructures (i.e., nanorods and nanowires) formed using NP arrays as catalysts, should have broad applications in catalysis, information technology, photovoltaics and biomedical engineering.We demonstrate a simple and clean physical

  19. Single-pulse transformation of Ag thin film into nanoparticles via laser-induced dewetting

    NASA Astrophysics Data System (ADS)

    Oh, Yoonseok; Lee, Myeongkyu

    2017-03-01

    In this study, we show that Ag thin films deposited on glass can be transformed into nanoparticles by laser-induced dewetting using a nanosecond-pulsed Nd:YAG laser. The film could be completely dewetted by a single pulse and the pulse energy density required for a 10 nm-thick Ag film was 86 mJ/cm2 at λ = 1064 nm. This made it possible to dewet a film area of ∼10 cm2 by a single pulse with energy of 850 mJ. The produced particles exhibited a monomodal size distribution and the mean particle size increased as the initial film thickness increased. Repeated exposure to pulses induced no noticeable change in the particle size distribution. The initial film thickness was the only factor that determined the mean particle size. The absorption spectra of dewetted films were well consistent with the surface plasma resonance behaviors of metal nanoparticles. This process provides a facile and scalable method of forming metal nanoparticle arrays for plasmonic and other applications.

  20. Inhibitory effect of copper nanoparticles on rosin modified surfactant induced aggregation of lysozyme.

    PubMed

    Ishtikhar, Mohd; Usmani, Salman Sadullah; Gull, Nuzhat; Badr, Gamal; Mahmoud, Mohamed H; Khan, Rizwan Hasan

    2015-01-01

    Protein aggregation is associated with many serious diseases including Parkinson's and Alzheimer's. Protein aggregation is a primary problem related with the health of industrial workers who work with the surfactants, metal ions, and cosolvents. We have synthesized rosin-based surfactants, i.e., quaternary amines of rosin diethylaminoethyl esters (QRMAE), which is an ester of rosin acid with polyethylene glycol monomethyl ether. Here, we report the thermal aggregation of lysozyme induced by QRMAE at 65 °C and pH 7.4 for a given time period in which amorphous aggregates are formed and confirm that copper-nanoparticles have the ability to inhibit QRMAE-induced aggregation compared with zinc and silver-nanoparticles. Aggregation experiments was evaluated using several spectroscopic methods and dye binding assay, such as turbidity, Rayleigh light scattering, 1-anilino-8-naphthalene sulfonate (ANS), Thioflavin T (Th T), congo red (CR) and circular dichroism (CD), that was further supported by scanning electron microscopy (SEM) and SEM with EDX. The therapeutic use of nanoparticles and the fact that rosin possesses excellent film-forming properties, and that its derivatives have pharmaceuticals application such as micro encapsulation, coating and film forming, it's matrix materials are used for sustained and controlled release tablets, renders importance and application to the present study.

  1. Silver Nanoparticles Induce HePG-2 Cells Apoptosis Through ROS-Mediated Signaling Pathways

    NASA Astrophysics Data System (ADS)

    Zhu, Bing; Li, Yinghua; Lin, Zhengfang; Zhao, Mingqi; Xu, Tiantian; Wang, Changbing; Deng, Ning

    2016-04-01

    Recently, silver nanoparticles (AgNPs) have been shown to provide a novel approach to overcome tumors, especially those of hepatocarcinoma. However, the anticancer mechanism of silver nanoparticles is unclear. Thus, the purpose of this study was to estimate the effect of AgNPs on proliferation and activation of ROS-mediated signaling pathway on human hepatocellular carcinoma HePG-2 cells. A simple chemical method for preparing AgNPs with superior anticancer activity has been showed in this study. AgNPs were detected by transmission electronic microscopy (TEM) and energy dispersive X-ray (EDX). The size distribution and zeta potential of silver nanoparticles were detected by Zetasizer Nano. The average size of AgNPs (2 nm) observably increased the cellular uptake by endocytosis. AgNPs markedly inhibited the proliferation of HePG-2 cells through induction of apoptosis with caspase-3 activation and PARP cleavage. AgNPs with dose-dependent manner significantly increased the apoptotic cell population (sub-G1). Furthermore, AgNP-induced apoptosis was found dependent on the overproduction of reactive oxygen species (ROS) and affecting of MAPKs and AKT signaling and DNA damage-mediated p53 phosphorylation to advance HePG-2 cells apoptosis. Therefore, our results show that the mechanism of ROS-mediated signaling pathways may provide useful information in AgNP-induced HePG-2 cell apoptosis.

  2. Lipidoid nanoparticle mediated silencing of Mcl-1 induces apoptosis in mantle cell lymphoma

    PubMed Central

    Knapp, Christopher M; He, Jia; Lister, John

    2016-01-01

    Conventional chemo-immunotherapy fails to cure the majority of mantle cell lymphoma patients and causes substantial toxicity. Resistant mantle cell lymphoma cells commonly overexpress and are dependent on the anti-apoptotic protein, Mcl-1, for survival. In this study, we use potent lipidoid nanoparticles to deliver siRNA to silence Mcl-1 expression. Studies were conducted using two different mantle cell lymphoma cell lines, a normal (JeKo-1) and an aggressive (MAVER-1) line, to assess the ability of lipidoid nanoparticles to be used broadly in the treatment of mantle cell lymphoma. Mcl-1 mRNA silencing and protein knockdown was observed as early as one day after treatment and the lipidoid nanoparticles achieved sustained silencing of Mcl-1 mRNA for at least four days in both JeKo-1 and MAVER-1 cells. Eighty percent silencing was achieved at three days post-transfection in JeKo-1 cells while 50% silencing was achieved in MAVER-1 cells, which are more resistant to transfection. Interestingly, silencing of Mcl-1 induced apoptosis in nearly 30% of both JeKo-1 and MAVER-1 cells three days post-transfection. Additionally, Mcl-1 silencing and the resultant apoptosis in mantle cell lymphoma cells were dose dependent. These data suggest that lipidoid nanoparticles siRNA therapy targeting Mcl-1 has potential as a new treatment modality for mantle cell lymphoma and many other cancers that overexpress Mcl-1. The combination of anti-Mcl-1 lipidoid nanoparticles with other forms of targeted therapy offers hope for reducing or replacing cytotoxic chemotherapy as standard treatment for mantle cell lymphoma. PMID:27022142

  3. Lipidoid nanoparticle mediated silencing of Mcl-1 induces apoptosis in mantle cell lymphoma.

    PubMed

    Knapp, Christopher M; He, Jia; Lister, John; Whitehead, Kathryn A

    2016-05-01

    Conventional chemo-immunotherapy fails to cure the majority of mantle cell lymphoma patients and causes substantial toxicity. Resistant mantle cell lymphoma cells commonly overexpress and are dependent on the anti-apoptotic protein, Mcl-1, for survival. In this study, we use potent lipidoid nanoparticles to deliver siRNA to silence Mcl-1 expression. Studies were conducted using two different mantle cell lymphoma cell lines, a normal (JeKo-1) and an aggressive (MAVER-1) line, to assess the ability of lipidoid nanoparticles to be used broadly in the treatment of mantle cell lymphoma. Mcl-1 mRNA silencing and protein knockdown was observed as early as one day after treatment and the lipidoid nanoparticles achieved sustained silencing of Mcl-1 mRNA for at least four days in both JeKo-1 and MAVER-1 cells. Eighty percent silencing was achieved at three days post-transfection in JeKo-1 cells while 50% silencing was achieved in MAVER-1 cells, which are more resistant to transfection. Interestingly, silencing of Mcl-1 induced apoptosis in nearly 30% of both JeKo-1 and MAVER-1 cells three days post-transfection. Additionally, Mcl-1 silencing and the resultant apoptosis in mantle cell lymphoma cells were dose dependent. These data suggest that lipidoid nanoparticles siRNA therapy targeting Mcl-1 has potential as a new treatment modality for mantle cell lymphoma and many other cancers that overexpress Mcl-1. The combination of anti-Mcl-1 lipidoid nanoparticles with other forms of targeted therapy offers hope for reducing or replacing cytotoxic chemotherapy as standard treatment for mantle cell lymphoma.

  4. Gardenia jasminoides extract-capped gold nanoparticles reverse hydrogen peroxide-induced premature senescence.

    PubMed

    Chae, Seon Yeong; Park, Sun Young; Park, Jin Oh; Lee, Kyu Jin; Park, Geuntae

    2016-11-01

    This study reports a green approach for synthesis of gold nanoparticles using Gardenia jasminoides extract, and specifically, can potentially enhance anti senescence activity. Biological synthesis of gold nanoparticles is ecofriendly and effective for the development of environmentally sustainable nanoparticles compared with existing methods. Here, we developed a simple, fast, efficient, and ecofriendly approach to the synthesis of gold nanoparticles by means of a Gardenia jasminoides extract. These G. jasminoides extract-capped gold nanoparticles (GJ-GNPs) were characterized by UV-vis, high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and Furrier transform infrared spectroscopy (FT-IR). The synthesized GJ-GNPs turned red and showed maximal absorbance at 540nm. Thus, GJ-GNPs were synthesized successfully. We hypothesized that GJ-GNPs would protect ARPE19 cells from hydrogen peroxide-induced premature senescence. SA-β-gal activity was elevated in hydrogen peroxide-treated cells, however, this effect was attenuated by GJ-GNP treatment. Moreover, compared with the normal control, hydrogen peroxide treatment significantly increased lysosome content of the cells and production of reactive oxygen species (ROS). GJ-GNPs effectively attenuated the increase in lysosome content and ROS production in these senescent cells. According to cell cycle analysis, G2/M arrest was promoted by hydrogen peroxide treatment in ARPE19 cells, however, this change was reversed by GJ-GNPs. Western blot analysis showed that treatment with GJ-GNPs increased the expression of p53, p21, SIRT3, HO-1, and NQO1 in senescent cells. Our findings should advance the understanding of premature senescence and may lead to therapeutic use of GJ-GNPs in retina-related regenerative medicine.

  5. 1,25 (OH)2D3 enhances PTH-induced Ca2+ transients in preosteoblasts by activating L-type Ca2+ channels

    NASA Technical Reports Server (NTRS)

    Li, W.; Duncan, R. L.; Karin, N. J.; Farach-Carson, M. C.

    1997-01-01

    We previously demonstrated electrophysiologically that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] shifts the activation threshold of L-type Ca2+ channels in osteoblasts toward the resting potential and prolongs mean open time. Presently, we used single-cell Ca2+ imaging to study the combined effects of 1,25(OH)2D3 and parathyroid hormone (PTH) during generation of Ca2+ transients in fura 2-loaded MC3T3-E1 cells. Pretreatment with 1,25(OH)2D3 concentrations, which alone did not produce Ca2+ transients, consistently enhanced Ca2+ responses to PTH. Enhancement was dose dependent over the range of 1 to 10 nM and was blocked by pretreatment with 5 microM nitrendipine during pretreatment. A 1,25(OH)2D3 analog that activates L-type channels and shifts their activation threshold also enhanced PTH responses. In contrast, an analog devoid of membrane Ca2+ effects did not enhance PTH-induced Ca2+ transients. The PTH-induced Ca2+ transient involved activation of a dihydropyridine-insensitive cation channel that was inhibited by Gd3+. Together, these data suggest that 1,25(OH)2D3 increases osteoblast responsiveness to PTH through rapid modification of L-type Ca2+ channel gating properties, whose activation enhances Ca2+ entry through other channels such as the PTH-responsive, Gd(3+)-sensitive cation channel.

  6. Extravasation of blood-borne immunoglobulin G through blood-brain barrier during adrenaline-induced transient hypertension in the rat.

    PubMed

    Kuang, Fang; Wang, Bai-Ren; Zhang, Ping; Fei, Ling-Ling; Jia, Yi; Duan, Xiao-Li; Wang, Xi; Xu, Zhen; Li, Gai-Li; Jiao, Xi-Ying; Ju, Gong

    2004-06-01

    The effect of transient hypertension on blood-brain barrier (BBB) permeability, particularly on extravasation of immunoglobulin G (IgG), has not been fully understood. In the present experiment, we investigated the time course of endogenous albumin and IgG extravasation through BBB and the localization of extravasated IgG in brain parenchyma during adrenaline(AD)-induced transient hypertension in the rat by using Evans blue fluorescence, immunohistochemistry, and Western blot. The results showed that a bolus injection of AD (10 microg/kg) induced a transient elevation of arterial pressure lasting about 1 min. The endogenous albumin and IgG entered the brain parenchyma via BBB only when hypertension occurred. Electron microscopically, the IgG-like immunoreactivities were predominantly seen in the cytoplasm of endothelia of capillaries, pericytes, extracellular space of parenchyma, and the cytoplasm of glial cells. The results suggest that circulating IgG or antibodies might contact the structures of brain parenchyma through passage of BBB when its permeability is temporally changed by transient hypertension. This phenomenon implies a possible mechanism of pathogenesis for immune-mediated diseases in the brain.

  7. Investigating inhibition of microbes inducing microbiologically-influenced-corrosion by Tectona grandis based Fe-nanoparticle material

    NASA Astrophysics Data System (ADS)

    Okeniyi, Joshua Olusegun; Omotosho, Olugbenga Adeshola; Inyang, Michael Anietie; Okeniyi, Elizabeth Toyin; Nwaokorie, Ikechi Thaddeus; Adidi, Emmanuel Amanogho; Owoeye, Taiwo Felicia; Nwakudu, Kelechukwu Chinedu; Akinlabu, Deborah Kehinde; Gabriel, Olanrewaju Oyewale; Taiwo, Olugbenga Samson; Awotoye, Olufisayo Adebola

    2017-02-01

    In this paper, inhibition of microbes inducing microbiologically-influenced-corrosion (MIC) of metals by Tectona grandis based Fe (iron) Nanoparticle material was investigated. For this, extract was obtained from the leaf of Tectona grandis and this was employed as precursor for synthesizing the Fe-nanoparticle material. From this, the synthesized plant extract based nanoparticle material was characterized using scanning electron microscopy and energy dispersive spectroscopy (SEM+EDS) instrument. The developed Fe bio-nanoparticle material was then employed for sensitivity and/or resistance study application against different strains of microbes that are known to induce microbiologically-influenced-corrosion, in metallic materials, and for this, microbial growth inhibition effect was compared with that from a commercial antibiotic employed as control. Results showed that the Tectona grandis based Fe-nanoparticle exhibited good inhibition effects on the growth of many of the MIC inducing microbes investigated. Sensitivity measures of zone of inhibition against the growth of MIC inducing microbial strains either outperformed or compares well with that obtained from the commercial antibiotic control, in the study. These results indicate positive prospect on the suitability of Fe bio-nanoparticle for corrosion inhibition applications for the protection of metals against microbiological corrosion influencing environment.

  8. Cancer Theranostic Nanoparticles Self-Assembled from Amphiphilic Small Molecules with Equilibrium Shift-Induced Renal Clearance

    PubMed Central

    Ma, Yuan; Mou, Quanbing; Sun, Mo; Yu, Chunyang; Li, Jianqi; Huang, Xiaohua; Zhu, Xinyuan; Yan, Deyue; Shen, Jian

    2016-01-01

    Nano drug delivery systems have emerged as promising candidates for cancer therapy, whereas their uncertainly complete elimination from the body within specific timescales restricts their clinical translation. Compared with hepatic clearance of nanoparticles, renal excretion of small molecules is preferred to minimize the agent-induced toxicity. Herein, we construct in vivo renal-clearable nanoparticles, which are self-assembled from amphiphilic small molecules holding the capabilities of magnetic resonance imaging (MRI) and chemotherapy. The assembled nanoparticles can accumulate in tumor tissues for their nano-characteristics, while the small molecules dismantled from the nanoparticles can be efficiently cleared by kidneys. The renal-clearable nanoparticles exhibit excellent tumor-inhibition performance as well as low side effects and negligible chronic toxicity. These results demonstrate a potential strategy for small molecular nano drug delivery systems with obvious anticancer effect and low-toxic metabolism pathway for clinical applications. PMID:27446502

  9. Plasmon-induced optical switching of electrical conductivity in porous anodic aluminum oxide films encapsulated with silver nanoparticle arrays.

    PubMed

    Huang, Chen-Han; Lin, Hsing-Ying; Lau, Ben-Chao; Liu, Chih-Yi; Chui, Hsiang-Chen; Tzeng, Yonhua

    2010-12-20

    We report on plasmon induced optical switching of electrical conductivity in two-dimensional (2D) arrays of silver (Ag) nanoparticles encapsulated inside nanochannels of porous anodic aluminum oxide (AAO) films. The reversible switching of photoconductivity greatly enhanced by an array of closely spaced Ag nanoparticles which are isolated from each other and from the ambient by thin aluminum oxide barrier layers are attributed to the improved electron transport due to the localized surface plasmon resonance and coupling among Ag nanoparticles. The photoconductivity is proportional to the power, and strongly dependent on the wavelength of light illumination. With Ag nanoparticles being isolated from the ambient environments by a thin layer of aluminum oxide barrier layer of controlled thickness in nanometers to tens of nanometers, deterioration of silver nanoparticles caused by environments is minimized. The electrochemically fabricated nanostructured Ag/AAO is inexpensive and promising for applications to integrated plasmonic circuits and sensors.

  10. Salt-induced aggregation of gold nanoparticles for photoacoustic imaging and photothermal therapy of cancer

    NASA Astrophysics Data System (ADS)

    Sun, Mengmeng; Liu, Fei; Zhu, Yukun; Wang, Wansheng; Hu, Jin; Liu, Jing; Dai, Zhifei; Wang, Kun; Wei, Yen; Bai, Jing; Gao, Weiping

    2016-02-01

    The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT.The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT. Electronic supplementary

  11. Two-stage kinetics of field-induced aggregation of medium-sized magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Ezzaier, H.; Alves Marins, J.; Razvin, I.; Abbas, M.; Ben Haj Amara, A.; Zubarev, A.; Kuzhir, P.

    2017-03-01

    The present paper is focused on the theoretical and experimental study of the kinetics of field-induced aggregation of magnetic nanoparticles of a size range of 20-100 nm. Our results demonstrate that (a) in polydisperse suspensions, the largest particles could play a role of the centers of nucleation for smaller particles during the earliest heterogeneous nucleation stage; (b) an intermediate stage of the aggregate growth (due to diffusion and migration of individual nanoparticles towards the aggregates) is weakly influenced by the magnetic field strength, at least at high supersaturation; (c) the stage of direct coalescence of drop-like aggregates (occurring under magnetic attraction between them) plays a dominant role at the intermediate and late stages of the phase separation, with the time scale decreasing as a square of the aggregate magnetization.

  12. Laser-induced incandescence of titania nanoparticles synthesized in a flame

    NASA Astrophysics Data System (ADS)

    Cignoli, F.; Bellomunno, C.; Maffi, S.; Zizak, G.

    2009-09-01

    Laser induced incandescence experiments were carried out in a flame reactor during titania nanoparticle synthesis. The structure of the reactor employed allowed for a rather smooth particle growth along the flame axis, with limited mixing of different size particles. Particle incandescence was excited by the 4th harmonic of a Nd:YAG laser. The radiation emitted from the particles was recorded in time and checked by spectral analysis. Results were compared with measurements from transmission electron microscopy of samples taken at the same locations probed by incandescence. This was done covering a portion of the flame length within which a particle size growth of a factor of about four was detected . The incandescence decay time was found to increase monotonically with particle size. The attainment of a process control tool in nanoparticle flame synthesis appears to be realistic.

  13. Silver nanoparticle-induced degranulation observed with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

    2010-02-01

    The use of AgNP is becoming more and more widespread in biomedical field. But compared with the promising bactericidal function, other physiological effects of AgNP on cells are relatively scant. In this research, we propose quantitative phase microscopy (QPM) as a new method to study the degranulation, and AgNP-induced RBL-2H3 cell degranulation is studied as well. Firstly, HeLa cells as the cell control and PBS as the solvent control, we measured the cell volume and cross section profile (x-z plane) with QPM. The results showed that the volume and cross section profile changed only the RBL-2H3 cells exposed to calcium ionophore A23187, which demonstrates the validity of QPM in degranulation research. Secondly, 50μg/mL of AgNP was used instead of A23187, and the measurement of cell volume and cross section profile was carried out again. RBL-2H3 cell volume increased immediately after AgNP was added, and cross section profile showed that the cell surface became granulated, but HeLa cell was lack of that effect. Phase images obviously indicated the RBL-2H3 cell deformation. Thirdly, stained with Fluo-3/AM, intracellular calcium Ca2+]i of single RBL-2H3 cell treated with AgNP was observed with fluorescent microscopy; incubated with AgNP for 20min, the supernatant of RBL-2H3 cells was collected and reacted with o-phthalaldehyde (OPA), then the fluorescent intensity of histamine-OPA complex was assayed with spectrofluorometer. The results of Ca2+]i and histamine increase showed that degranulation of AgNP-induced RBL-2H3 cell occurred. So, the cell volume was used as a parameter of degranulation in our study and AgNP-induced RBL-2H3 cells degranulation was confirmed by the cell volume increment, cross section profile change, and [Ca2+]i and histamine in supernatant increase.

  14. Titanium dioxide nanoparticles induce emphysema-like lung injury in mice.

    PubMed

    Chen, Huei-Wen; Su, Sheng-Fang; Chien, Chiang-Ting; Lin, Wei-Hsiang; Yu, Sung-Liang; Chou, Cheng-Chung; Chen, Jeremy J W; Yang, Pan-Chyr

    2006-11-01

    Titanium dioxide nanoparticles (nanoTiO2) have been widely used as a photocatalyst in air and water cleaning. However, these nanoparticles inhalation can induce pulmonary toxicity and its mechanism is not fully understood. In this study we investigated the pulmonary toxicity of nanoTiO2 and its molecular pathogenesis. The adult male ICR mice were exposed to intratracheal single dose of 0.1 or 0.5 mg nanoTiO2 (19-21 nm) and lung tissues were collected at 3rd day, 1st wk, and 2nd wk for morphometric, microarray gene expression, and pathway analyses. NanoTiO2 can induce pulmonary emphysema, macrophages accumulation, extensive disruption of alveolar septa, type II pneumocyte hyperplasia, and epithelial cell apoptosis. NanoTiO2 induced differential expression of hundreds of genes include activation of pathways involved in cell cycle, apoptosis, chemokines, and complement cascades. In particular, nanoTiO2 up-regulates placenta growth factor (PlGF) and other chemokines (CXCL1, CXCL5, and CCL3) expressions that may cause pulmonary emphysema and alveolar epithelial cell apoptosis. Cultured human THP-1 cell-derived macrophages treated with nanoTiO2 in vitro also resulted in up-regulations of PlGF, CXCL1, CXCL5, and CCL3. These results indicated that nanoTiO2 can induce severe pulmonary emphysema, which may be caused by activation of PlGF and related inflammatory pathways.

  15. Nickel oxide nanoparticles induce inflammation and genotoxic effect in lung epithelial cells.

    PubMed

    Capasso, Laura; Camatini, Marina; Gualtieri, Maurizio

    2014-04-07

    Nickel oxide nanoparticles (NiONPs) toxicity has been evaluated in the human pulmonary epithelial cell lines: BEAS-2B and A549. The nanoparticles, used at the doses of 20, 40, 60, 80, 100 μg/ml, induced a significant reduction of cell viability and an increase of apoptotic and necrotic cells at 24h. A significant release of interleukin-6 and -8 was assessed after 24h of treatment, even intracellular ROS increased already at 45 min after exposure. The results obtained evidenced that the cytokines release was dependent on mitogen activated protein kinases (MAPK) cascade through the induction of NF-kB pathway. NiONPs induced cell cycle alteration in both the cell lines even in different phases and these modifications may be induced by the NPs genotoxic effect, suggested by the nuclear translocation of phospho-ATM and phospho-ATR. Our results confirm the cytotoxic and pro-inflammatory potential of NiONPs. Moreover their ability in inducing DNA damage responses has been demonstrated. Such effects were present in A549 cells which internalize the NPs and BEAS-2B cells in which endocytosis has not been observed.

  16. Stability and magnetically induced heating behavior of lipid-coated Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Allam, Ayat A.; Sadat, Md Ehsan; Potter, Sarah J.; Mast, David B.; Mohamed, Dina F.; Habib, Fawzia S.; Pauletti, Giovanni M.

    2013-10-01

    -coated SPIONs on colloidal stability without compromising magnetically induced hyperthermia properties. Since phospholipids are biocompatible, these unique lipid-coated Fe3O4 nanoparticles offer exciting opportunities as thermoresponsive drug delivery carriers for targeted, stimulus-induced therapeutic interventions.

  17. Oxygen vacancy induced by La and Fe into ZnO nanoparticles to modify ferromagnetic ordering

    NASA Astrophysics Data System (ADS)

    Verma, Kuldeep Chand; Kotnala, R. K.

    2016-05-01

    We reported long-range ferromagnetic interactions in La doped Zn0.95Fe0.05O nanoparticles that mediated through lattice defects or vacancies. Zn0.92Fe0.05La0.03O (ZFLaO53) nanoparticles were synthesized by a sol-gel process. X-ray fluorescence spectrum of ZFLaO53 detects the weight percentage of Zn, Fe, La and O. X-ray diffraction shows the hexagonal Wurtzite ZnO phase. The Rietveld refinement has been used to calculate the lattice parameters and the position of Zn, Fe, La and O atoms in the Wurtzite unit cell. The average size of ZFLaO53 nanoparticles is 99 nm. The agglomeration type product due to OH ions with La results into ZnO nanoparticles than nanorods that found in pure ZnO and Zn0.95Fe0.05O sample. The effect of doping concentration to induce Wurtzite ZnO structure and lattice defects has been analyzed by Raman active vibrational modes. Photoluminescence spectra show an abnormal emission in both UV and visible region, and a blue shift at near band edge is formed with doping. The room temperature magnetic measurement result into weak ferromagnetism but pure ZnO is diamagnetic. However, the temperature dependent magnetic measurement using zero-field and field cooling at dc magnetizing field 500 Oe induces long-range ferromagnetic ordering. It results into antiferromagnetic Neel temperature of ZFLaO53 at around 42 K. The magnetic hysteresis is also measured at 200, 100, 50 and 10 K measurement that indicate enhancement in ferromagnetism at low temperature. Overall, the La doping into Zn0.95Fe0.05O results into enhanced antiferromagnetic interaction as well as lattice defects/vacancies. The role of the oxygen vacancy as the dominant defects in doped ZnO must form Bound magnetic polarons has been described.

  18. Direct measurement of transient pulses induced by laser and heavy ion irradiation in deca-nanometer devices.

    SciTech Connect

    Knudson, A. R.; Torres, A.; McMorrow, D.; Ferlet-Cavrois, Veronique; Schwank, James Ralph; Paillet, Philippe; Melinger, J. S.; Tosti, L.; Jahan, C.; Barna, Gabriel; Faynot, O.; Shaneyfelt, Marty Ray; Campbell, A. B.; Gaillardin, M.; Hirose, K.; Vizkelethy, Gyorgy

    2005-07-01

    This paper investigates the transient response of 50-nm gate length fully and partially depleted SOI and bulk devices to pulsed laser and heavy ion microbeam irradiations. The measured transient signals on 50-nm fully depleted devices are very short, and the collected charge is small compared to older 0.25-{micro}m generation SOI and bulk devices. We analyze in detail the influence of the SOI architecture (fully or partially depleted) on the pulse duration and the amount of bipolar amplification. For bulk devices, the doping engineering is shown to have large effects on the duration of the transient signals and on the charge collection efficiency.

  19. Cisplatin-induced self-assembly of graphene oxide sheets into spherical nanoparticles for damaging sub-cellular DNA.

    PubMed

    Nandi, Aditi; Mallick, Abhik; More, Piyush; Sengupta, Poulomi; Ballav, Nirmalya; Basu, Sudipta

    2017-01-24

    This report describes the hitherto unobserved cisplatin induced self-assembly of 2D-graphene oxide sheets into 3D-spherical nano-scale particles. These nanoparticles can encompass dual DNA damaging drugs simultaneously. A combination of confocal microscopy, gel electrophoresis and flow cytometry studies clearly demonstrated that these novel nanoparticles can internalize into cancer cells by endocytosis, localize into lysosomes, and damage DNA, leading to apoptosis. Cell viability assays indicated that these nanoparticles were more cytotoxic towards cancer cells compared to healthy cells.

  20. Epidermal Growth Factor Receptor Transactivation by the Cannabinoid Receptor (CB1) and Transient Receptor Potential Vanilloid 1 (TRPV1) Induces Differential Responses in Corneal Epithelial Cells

    DTIC Science & Technology

    2010-01-01

    inhibitors of proteolytic release of heparin bound EGF ( HB -EGF). CB1- induced Ca2þ transients were reduced during exposure to either the CB1 antagonist...blockage eliminated this response. Furthermore, EGFR transactivation was abolished by inhibitors of proteolytic release of heparin bound EGF ( HB -EGF...IL-8 or IL-6 Chemiluminescent Immunoassay ; R&D Systems, Minneapolis, MN). The cells were washed with basic medium and then exposed to CPZ, or AM251

  1. Salt-induced aggregation of gold nanoparticles for photoacoustic imaging and photothermal therapy of cancer.

    PubMed

    Sun, Mengmeng; Liu, Fei; Zhu, Yukun; Wang, Wansheng; Hu, Jin; Liu, Jing; Dai, Zhifei; Wang, Kun; Wei, Yen; Bai, Jing; Gao, Weiping

    2016-02-28

    The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT.

  2. PPS nanoparticles as versatile delivery system to induce systemic and broad mucosal immunity after intranasal administration.

    PubMed

    Stano, Armando; van der Vlies, André J; Martino, Mikael M; Swartz, Melody A; Hubbell, Jeffrey A; Simeoni, Eleonora

    2011-01-17

    Degradable polymer nanoparticles (NPs, 50 nm) based on polypropylene sulfide (PPS) were conjugated to thiolated antigen and adjuvant proteins by reversible disulfide bonds and evaluated in mucosal vaccination. Ovalbumin was used as a model antigen, and antigen-conjugated NPs were administered intranasally in the mouse. We show penetration of nasal mucosae, transit via M cells, and uptake by antigen-presenting cells in the nasal-associated lymphoid tissue. Ovalbumin-conjugated NPs induced cytotoxic T lymphocytic responses in lung and spleen tissues, as well as humoral response in mucosal airways. Co-conjugation of the TLR5 ligand flagellin further enhanced humoral responses in the airways as well as in the distant vaginal and rectal mucosal compartments and induced cellular immune responses with a Th1 bias, in contrast with free flagellin. The PPS NP platform thus appears interesting as a platform for intranasally-administered mucosal vaccination for inducing broad mucosal immunity.

  3. HIV-1-Induced Small T Cell Syncytia Can Transfer Virus Particles to Target Cells through Transient Contacts

    PubMed Central

    Symeonides, Menelaos; Murooka, Thomas T.; Bellfy, Lauren N.; Roy, Nathan H.; Mempel, Thorsten R.; Thali, Markus

    2015-01-01

    HIV-1 Env mediates fusion of viral and target cell membranes, but it can also mediate fusion of infected (producer) and target cells, thus triggering the formation of multinucleated cells, so-called syncytia. Large, round, immobile syncytia are readily observable in cultures of HIV-1-infected T cells, but these fast growing “fusion sinks” are largely regarded as cell culture artifacts. In contrast, small HIV-1-induced syncytia were seen in the paracortex of peripheral lymph nodes and other secondary lymphoid tissue of HIV-1-positive individuals. Further, recent intravital imaging of lymph nodes in humanized mice early after their infection with HIV-1 demonstrated that a significant fraction of infected cells were highly mobile, small syncytia, suggesting that these entities contribute to virus dissemination. Here, we report that the formation of small, migratory syncytia, for which we provide further quantification in humanized mice, can be recapitulated in vitro if HIV-1-infected T cells are placed into 3D extracellular matrix (ECM) hydrogels rather than being kept in traditional suspension culture systems. Intriguingly, live-cell imaging in hydrogels revealed that these syncytia, similar to individual infected cells, can transiently interact with uninfected cells, leading to rapid virus transfer without cell-cell fusion. Infected cells were also observed to deposit large amounts of viral particles into the extracellular space. Altogether, these observations suggest the need to further evaluate the biological significance of small, T cell-based syncytia and to consider the possibility that these entities do indeed contribute to virus spread and pathogenesis. PMID:26703714

  4. Immersion infection of germ-free zebrafish with Listeria monocytogenes induces transient expression of innate immune response genes

    PubMed Central

    Shan, Ying; Fang, Chun; Cheng, Changyong; Wang, Yong; Peng, Jinrong; Fang, Weihuan

    2015-01-01

    Zebrafish, Denio rerio, can be an alternative to other classic animal models for human infectious diseases to examine the processes of microbial infections and host–pathogen interactions in vivo because of their small body dimension but large clutch size. We established germ-free zebrafish infection models of Listeria monocytogenes through different routes of infection: oral immersion and injection via yolk sac, brain ventricle and blood island. Immersion of zebrafish larva even with 1010 CFU/mL L. monocytogenes EGDe strain in egg water was unable to cause mortality, but GFP-expressing bacteria in the gut lumen can be observed in frozen sections. Several selected maker genes of the innate immune system, including cyp1a, irg1l, il1b, and mmp9, were significantly induced by oral immersion not only with strain EGDe, but also with strain M7 and L. innocua, though to a lesser degree (P < 0.01). Such induction appears to be transient with peak at 48 h post-infection, but returned to basal level at 72 h post-infection. Of the three injection routes, mortality after infection by yolk sac was 80% in early stage of infection. Few eggs can survive and hatch. Injection into zebrafish embryos via brain ventricle or blood island led to progressive lethal infection. L. mocytogenes EGDe showed steady replication in the fish embryos and was far more pathogenic than strain M7, which is consistent with findings in the murine model. We conclude that zebrafish can serve as susceptible and microscopically visible infection models for L. monocytogenes via different routes and can be applied to further studies on the interactions between bacterial virulence factors and host immune responses. PMID:25972853

  5. HIV-1-Induced Small T Cell Syncytia Can Transfer Virus Particles to Target Cells through Transient Contacts.

    PubMed

    Symeonides, Menelaos; Murooka, Thomas T; Bellfy, Lauren N; Roy, Nathan H; Mempel, Thorsten R; Thali, Markus

    2015-12-12

    HIV-1 Env mediates fusion of viral and target cell membranes, but it can also mediate fusion of infected (producer) and target cells, thus triggering the formation of multinucleated cells, so-called syncytia. Large, round, immobile syncytia are readily observable in cultures of HIV-1-infected T cells, but these fast growing "fusion sinks" are largely regarded as cell culture artifacts. In contrast, small HIV-1-induced syncytia were seen in the paracortex of peripheral lymph nodes and other secondary lymphoid tissue of HIV-1-positive individuals. Further, recent intravital imaging of lymph nodes in humanized mice early after their infection with HIV-1 demonstrated that a significant fraction of infected cells were highly mobile, small syncytia, suggesting that these entities contribute to virus dissemination. Here, we report that the formation of small, migratory syncytia, for which we provide further quantification in humanized mice, can be recapitulated in vitro if HIV-1-infected T cells are placed into 3D extracellular matrix (ECM) hydrogels rather than being kept in traditional suspension culture systems. Intriguingly, live-cell imaging in hydrogels revealed that these syncytia, similar to individual infected cells, can transiently interact with uninfected cells, leading to rapid virus transfer without cell-cell fusion. Infected cells were also observed to deposit large amounts of viral particles into the extracellular space. Altogether, these observations suggest the need to further evaluate the biological significance of small, T cell-based syncytia and to consider the possibility that these entities do indeed contribute to virus spread and pathogenesis.

  6. Case Study of Somaclonal Variation in Resistance Genes Mlo and Pme3 in Flaxseed (Linum usitatissimum L.) Induced by Nanoparticles

    PubMed Central

    Kokina, Inese; Jermaļonoka, Marija; Bankovska, Linda; Gerbreders, Vjačeslavs; Ogurcovs, Andrejs; Jahundoviča, Inese

    2017-01-01

    Nanoparticles influence on genome is investigated worldwide. The appearance of somaclonal variation is a cause of great concern for any micropropagation system. Somaclonal variation describes the tissue-culture-induced phenotypic and genotypic variations. This paper shows the results of somaclonal variation in two resistance genes pectin methylesterase and Mlo-like protein in all tissue culture development stages, as donor plant, calluses, and regenerants of Linum usitatissimum induced by gold and silver nanoparticles. In this paper, it was essential to obtain DNA material from all tissue culture development stages from one donor plant to record changes in each nucleotide sequence. Gene region specific primers were developed for resistance genes such as Mlo and Pme3 to define the genetic variability in tissue culture of L. usitatissimum. In recent years, utilization of gold and silver nanoparticles in tissue culture is increased and the mechanisms of changes in genome induced by nanoparticles still remain unclear. Obtained data show the somaclonal variation increase in calluses obtained from one donor plant and grown on medium supplemented by gold nanoparticles (Mlo 14.68 ± 0.98; Pme3 2.07 ± 0.87) or silver nanoparticles (Mlo 12.01 ± 0.43; Pme3 10.04 ± 0.46) and decrease in regenerants. Morphological parameters of calluses showed a number of differences between each investigated culture group. PMID:28326314

  7. Exposure to nickel oxide nanoparticles induces pulmonary inflammation through NLRP3 inflammasome activation in rats

    PubMed Central

    Cao, Zhengwang; Fang, Yiliang; Lu, Yonghui; Qian, Fenghua; Ma, Qinglong; He, Mingdi; Pi, Huifeng; Yu, Zhengping; Zhou, Zhou

    2016-01-01

    With recent advances in the manufacture and application of nickel oxide nanoparticles (NiONPs), concerns about their adverse effects on the respiratory system are increasing. However, the underlying cellular and molecular mechanisms of NiONP-induced pulmonary toxicity remain unclear. In this study, we focused on the impacts of NiONPs on pulmonary inflammation and investigated whether the NLRP3 inflammasome is involved in NiONP-induced pulmonary inflammation and injury. NiONP suspensions were administered by single intratracheal instillation to rats, and inflammatory responses were evaluated at 3 days, 7 days, or 28 days after treatment. NiONP exposure resulted in sustained pulmonary inflammation accompanied by inflammatory cell infiltration, alveolar proteinosis, and cytokine secretion. Expression of Nlrp3 was markedly upregulated by the NiONPs, which was accompanied by overexpression of the active form of caspase-1 (p20) and interleukin (IL)-1β secretion in vivo. NiONP-induced IL-1β secretion was partially prevented by co-treatment with a caspase-1 inhibitor in macrophages. Moreover, siRNA-mediated Nlrp3 knockdown completely attenuated NiONP-induced cytokine release and caspase-1 activity in macrophages in vitro. In addition, NiONP-induced NLRP3 inflammasome activation requires particle uptake and reactive oxygen species production. Collectively, our findings suggest that the NLRP3 inflammasome participates in NiONP-induced pulmonary inflammation and offer new strategies to combat the pulmonary toxicity induced by NiONPs. PMID:27524893

  8. Investigations on heavy ion induced Single-Event Transients (SETs) in highly-scaled FinFETs

    NASA Astrophysics Data System (ADS)

    Gaillardin, M.; Raine, M.; Paillet, P.; Adell, P. C.; Girard, S.; Duhamel, O.; Andrieu, F.; Barraud, S.; Faynot, O.

    2015-12-01

    We investigate Single-Event Transients (SET) in different designs of multiple-gate devices made of FinFETs with various geometries. Heavy ion experimental results are explained by using a thorough charge collection analysis of fast transients measured on dedicated test structures. Multi-level simulations are performed to get new insights into the charge collection mechanisms in multiple-gate devices. Implications for multiple-gate device design hardening are finally discussed.

  9. Molecular Mechanism of Silver Nanoparticles-Induced Human Osteoblast Cell Death: Protective Effect of Inducible Nitric Oxide Synthase Inhibitor

    PubMed Central

    Zielinska, Ewelina; Tukaj, Cecylia; Radomski, Marek Witold; Inkielewicz-Stepniak, Iwona

    2016-01-01

    Background Silver nanoparticles (AgNPs) show strong antibacterial properties, making them excellent candidates to be used in orthopaedic repair and regeneration. However, there are concerns regarding the cytotoxicity of AgNPs and molecular mechanisms underlying AgNPs-induced bone cells toxicity have not been elucidated. Therefore, the aim of our study was to explore mechanisms of AgNPs-induced osteoblast cell death with particular emphasis on the role of nitric oxide (NO) generated by inducible nitric oxide synthase (iNOS). Methods and Result Silver nanoparticles used in this study were 18.3±2.6 nm in size, uncoated, spherical, regular shape and their zeta potential was -29.1±2.4 mV as measured by transmission electron microscopy (TEM) and zetasizer. The release of silver (Ag) from AgNPs was measured in cell culture medium by atomic absorption spectroscopy (AAS). The exposure of human osteoblast cells (hFOB 1.19) to AgNPs at concentration of 30 or 60 μg/mL for 24 or 48 hours, respectively resulted in cellular uptake of AgNPs and changes in cell ultrastructure. These changes were associated with apoptosis and necrosis as shown by flow cytometry and lactate dehydrogenase (LDH) assay as well as increased levels of pro-apoptotic Bax and decreased levels of anti-apoptotic Bcl-2 mRNA and protein. Importantly, we have found that AgNPs elevated the levels of nitric oxide (NO) with concomitant upregulation of inducible nitric oxide synthase (iNOS) mRNA and protein. A significant positive correlation was observed between the concentration of AgNPs and iNOS at protein and mRNA level (r = 0.837, r = 0.721, respectively; p<0.001). Finally, preincubation of osteoblast cells with N-iminoethyl-l-lysine (L-NIL), a selective iNOS inhibitor, as well as treating cells with iNOS small interfering RNAs (siRNA) significantly attenuated AgNPs-induced apoptosis and necrosis. Moreover, we have found that AgNPs-induced cells death is not related to Ag dissolution is cell culture medium

  10. Pathway of cytotoxicity induced by folic acid modified selenium nanoparticles in MCF-7 cells.

    PubMed

    Pi, Jiang; Jin, Hua; Liu, Ruiying; Song, Bing; Wu, Qing; Liu, Li; Jiang, Jinhuan; Yang, Fen; Cai, Huaihong; Cai, Jiye

    2013-02-01

    Selenium nanoparticles (Se NPs) have been recognized as promising materials for biomedical applications. To prepare Se NPs which contained cancer targeting methods and to clarify the cellular localization and cytotoxicity mechanisms of these Se NPs against cancer cells, folic acid protected/modified selenium nanoparticles (FA-Se NPs) were first prepared by a one-step method. Some morphologic and spectroscopic methods were obtained to prove the successfully formation of FA-Se NPs while free folate competitive inhibition assay, microscope, and several biological methods were used to determine the in vitro uptake, subcellular localization, and cytotoxicity mechanism of FA-Se NPs in MCF-7 cells. The results indicated that the 70-nm FA-Se NPs were internalized by MCF-7 cells through folate receptor-mediated endocytosis and targeted to mitochondria located regions through endocytic vesicles transporting. Then, the FA-Se NPs entered into mitochondria; triggered the mitochondria-dependent apoptosis of MCF-7 cells which involved oxidative stress, Ca(2)+ stress changes, and mitochondrial dysfunction; and finally caused the damage of mitochondria. FA-Se NPs released from broken mitochondria were transported into nucleus and further into nucleolus which then induced MCF-7 cell cycle arrest. In addition, FA-Se NPs could induce cytoskeleton disorganization and induce MCF-7 cell membrane morphology alterations. These results collectively suggested that FA-Se NPs could be served as potential therapeutic agents and organelle-targeted drug carriers in cancer therapy.

  11. Smac therapeutic Peptide nanoparticles inducing apoptosis of cancer cells for combination chemotherapy with Doxorubicin.

    PubMed

    Li, Mingxing; Liu, Peng; Gao, Guanhui; Deng, Jizhe; Pan, Zhengyin; Wu, Xu; Xie, Gaofeng; Yue, Caixia; Cho, Chi Hin; Ma, Yifan; Cai, Lintao

    2015-04-22

    Smac-conjugated nanoparticle (Smac-NP) was designed to induce the apoptosis of cancer cells and as a drug carrier for combination therapy. It contained three parts, a SmacN7 peptide which could induce apoptosis of cancer cells by interacting with XIAPs, the cell penetrating domain rich in arginine, and four hydrophobic tails for self-assembled Smac-NP. We demonstrated that Smac-NPs exerted an antitumor effect in breast cancer cell MDA-MB-231 and nonsmall lung cancer (NSCLC) cell H460, which efficiently inhibited cancer cells proliferation without influencing normal liver cell lines LO2. Smac-NPs also significantly induced apoptosis of MDA-MB-231 and H460 cells through activating pro-caspase-3, down-regulating the expression of antiapoptotic protein Bcl-2 and up-regulating the pro-apoptotic protein Bax. Furthermore, Smac-NPs could be explored as a drug delivery system to load hydrophobic drug such as DOX for combination therapy. The DOX-loaded nanoparticles (DOX-Smac-NPs) exhibited higher cellular uptake efficiency and antitumor effect. Our work provided a new insight into therapeutic peptides integrated with drug simultaneously in one system for cancer combination treatment.

  12. Laser-induced fluorescence reader with a turbidimetric system for sandwich-type immunoassay using nanoparticles.

    PubMed

    Kim, Y H; Lim, H B

    2015-07-09

    A unique laser-induced fluorescence (LIF) reader equipped with a turbidimetric system was developed for a sandwich-type immunoassay using nanoparticles. The system was specifically designed to reduce experimental error caused by particle loss, aggregation and sinking, and to improve analytical performance through ratiometric measurement of the fluorescence with respect to the turbidimetric absorbance. For application to determine the concentration of salinomycin, magnetic nanoparticles (MNPs) and FITC-doped silica nanoparticles (colored balls) immobilized with antibody were synthesized for magnetic extraction and for tagging as a fluorescence probe, respectively. The detection limit of about 39 pg mL(-1) was obtained, which was an improvement of about 2-fold compared to that obtained without employment of the turbidimetric system. Calibration linearity and sensitivity were also improved, with increase from 0.8601 to 0.9905 in the R(2)-coefficient and by 1.92-fold for the curve slope, respectively. The developed LIF reader has the potential to be used for fluorescence measurements using various nanomaterials, such as quantum dots.

  13. UV irradiation induced transformation of TiO2 nanoparticles in water: aggregation and photoreactivity.

    PubMed

    Sun, Jing; Guo, Liang-Hong; Zhang, Hui; Zhao, Lixia

    2014-10-21

    Transformation of nanomaterials in aqueous environment has significant impact on their behavior in engineered application and natural system. In this paper, UV irradiation induced transformation of TiO2 nanoparticles in aqueous solutions was demonstrated, and its effect on the aggregation and photocatalytic reactivity of TiO2 was investigated. UV irradiation of a TiO2 nanoparticle suspension accelerated nanoparticle aggregation that was dependent on the irradiation duration. The aggregation rate increased from <0.001 nm/s before irradiation to 0.027 nm/s after 50 h irradiation, resulting in aggregates with a hydrodynamic diameter of 623 nm. The isoelectric point of the suspension was lowered from 7.0 to 6.4 after irradiation, indicating less positive charges on the surface. ATR-FTIR spectra displayed successive growth of surface hydroxyl groups with UV irradiation which might be responsible for the change of surface charge and aggregation rate. UV irradiation also changed the photocatalytic degradation rate of Rhodamine B by TiO2, which initially increased with irradiation time, then decreased. Based on the photoluminescence decay and photocurrent collection data, the change was attributed to the variation in interparticle charge transfer kinetics. These results highlight the importance of light irradiation on the transformation and reactivity of TiO2 nanomaterials.

  14. Rapid synthesis of tin (IV) oxide nanoparticles by microwave induced thermohydrolysis

    SciTech Connect

    Jouhannaud, J. Rossignol, J.; Stuerga, D.

    2008-06-15

    Tin oxide nanopowders, with an average size of 5 nm, were prepared by microwave flash synthesis. Flash synthesis was performed in aqueous solutions of tin tetrachloride and hydrochloric acid using a microwave autoclave (RAMO system) specially designed by the authors. Energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, nitrogen adsorption isotherm analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), were used to characterize these nanoparticles. Compared with conventional synthesis, nanopowders can be produced in a short period (e.g. 60 s). In addition, high purity and high specific surface area are obtained. These characteristics are fundamental for gas sensing applications. - Graphical abstract: Tin oxide-based gas sensors have been extensively studied in recent years in order to understand and improve their sensing properties to a large variety of gaseous species. As is well known, high specific surface area increase the responses of gas sensors. Microwave-induced thermohydrolysis appears as an efficient way to produce nanoparticles in a very short time, with controlled size (4-5 nm) and high-specific area (160-190 m{sup 2} g{sup -1}). Pictogram represents our original microwave reactor, the RAMO (French acronym of Reacteur Autoclave Micro-Onde), containing the reactants and submitted to the microwave irradiation (multicolour candy represent obtained material), and a typical TEM image of the as-prepared SnO{sub 2} nanoparticles.

  15. Systematic Approach to Electrostatically Induced 2D Crystallization of Nanoparticles at Liquid Interfaces

    SciTech Connect

    Fukuto, M.; Kewalramani, S.; Wang, S.; Lin, Y.; Nguyen, G.; Wang, Q.; Yang, L.

    2011-02-07

    We report an experimental demonstration of a strategy for inducing two-dimensional (2D) crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situ X-ray scattering measurements at the liquid-vapor interface. The assembly was studied as a function of the solution pH, which was used to vary the charge on CPMV, and of the mole fraction of the cationic lipid in the binary lipid monolayer, which set the interface charge density. The 2D crystallization of CPMV occurred in a narrow pH range just above the particle's isoelectric point, where the particle charge was weakly negative, and only when the cationic-lipid fraction in the monolayer exceeded a threshold. The observed 2D crystals exhibited nearly the same packing density as the densest lattice plane within the known 3D crystals of CPMV. The above electrostatic approach of maximizing interfacial adsorption may provide an efficient route to the crystallization of nanoparticles at aqueous interfaces.

  16. Interface-induced disassembly of a self-assembled two-component nanoparticle system.

    PubMed

    Gao, Yan; Duc, Le T; Ali, Affira; Liang, Beverly; Liang, Jenn-Tai; Dhar, Prajnaparamita

    2013-03-19

    We present a study of static and dynamic interfacial properties of self-assembled polyelectrolyte complex nanoparticles (size 110-120 nm) containing entrapped surfactant molecules at a fluid/fluid interface. Surface tension vs time measurements of an aqueous solution of these polyelectrolyte complex nanoparticles (PCNs) show a concentration-dependent biphasic adsorption to the air/water interface while interfacial microrheology data show a concentration-dependent initial increase in the surface viscosity (up to 10(-7) N·m/s), followed by a sharp decrease (10(-9) N·m/s). Direct visualization of the air/water interface shows disappearance of particles from the interface over time. On the basis of these observations, we propose that the PCNs at fluid/fluid interfaces exist in two states: initial accumulation of PCNs at the air/water interface as nanoparticles, followed by interface induced disassembly of the accumulated PCNs into their components. The lack of change in particle size, charge, and viscosity of the bulk aqueous solution of PCNs with time indicates that this disintegration of the self-assembled PCNs is an interfacial phenomenon. Changes in energy encountered by the PCNs at the interface lead to instability of the self-assembled system and dissociation into its components. Such systems can be used for applications requiring directed delivery and triggered release of entrapped surfactants or macromolecules at fluid/fluid interfaces.

  17. Redox-active cerium oxide nanoparticles protect human dermal fibroblasts from PQ-induced damage.

    PubMed

    von Montfort, Claudia; Alili, Lirija; Teuber-Hanselmann, Sarah; Brenneisen, Peter

    2015-01-01

    Recently, it has been published that cerium (Ce) oxide nanoparticles (CNP; nanoceria) are able to downregulate tumor invasion in cancer cell lines. Redox-active CNP exhibit both selective pro-oxidative and antioxidative properties, the first being responsible for impairment of tumor growth and invasion. A non-toxic and even protective effect of CNP in human dermal fibroblasts (HDF) has already been observed. However, the effect on important parameters such as cell death, proliferation and redox state of the cells needs further clarification. Here, we present that nanoceria prevent HDF from reactive oxygen species (ROS)-induced cell death and stimulate proliferation due to the antioxidative property of these particles.

  18. Transport in superlattices of magnetic nanoparticles: coulomb blockade, hysteresis, and switching induced by a magnetic field.

    PubMed

    Tan, Reasmey P; Carrey, Julian; Desvaux, Céline; Grisolia, Jérémie; Renaud, Philippe; Chaudret, Bruno; Respaud, Marc

    2007-10-26

    We report on magnetotransport measurements on millimetric superlattices of Co-Fe nanoparticles surrounded by an organic layer. At low temperature, the transition between the Coulomb blockade and the conductive regime becomes abrupt and hysteretic. The transition between both regimes can be induced by a magnetic field, leading to a novel mechanism of magnetoresistance. Between 1.8 and 10 K, a high-field magnetoresistance attributed to magnetic disorder at the surface of the particles is also observed. Below 1.8 K, this magnetoresistance abruptly collapses and a low-field magnetoresistance is observed.

  19. Spatially optimized gene transfection by laser-induced breakdown of optically trapped nanoparticles

    NASA Astrophysics Data System (ADS)

    Arita, Yoshihiko; Torres-Mapa, Maria Leilani; Lee, Woei Ming; Čižmár, Tomáš; Campbell, Paul; Gunn-Moore, Frank J.; Dholakia, Kishan

    2011-02-01

    We demonstrate laser-induced breakdown of an optically trapped nanoparticle with a nanosecond laser pulse. Controllable cavitation within a microscope sample was achieved, generating shear stress to monolayers of live cells. This efficiently permeabilize their plasma membranes. We show that this technique is an excellent tool for plasmid-DNA transfection of cells with both reduced energy requirements and reduced cell lysis compared to previously reported approaches. Simultaneous multisite targeted nanosurgery of cells is also demonstrated using a spatial light modulator for parallelizing the technique.

  20. Tetraphenylethene-based aggregation-induced emission fluorescent organic nanoparticles: facile preparation and cell imaging application.

    PubMed

    Zhang, Xiqi; Liu, Meiying; Yang, Bin; Zhang, Xiaoyong; Wei, Yen

    2013-12-01

    Tetraphenylethene-based (TPE) aggregation-induced emission fluorescent organic nanoparticles (FONs) were facilely prepared via Schiff base condensation with ɛ-polylysine (Ply) and subsequent reduction to form stable CN covalent bond. Thus obtained TPE-Ply FONs were characterized by a series of techniques including fluorescent spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. Biocompatibility evaluation and cell uptake behavior of TPE-Ply FONs were further investigated to explore their potential biomedical application. We demonstrated that such FONs showed high water dispersibility, intense fluorescence, uniform morphology (100-200nm) and excellent biocompatibility, making them promising for cell imaging application.

  1. Oxidative stress induced by pure and iron-doped amorphous silica nanoparticles in subtoxic conditions.

    PubMed

    Napierska, Dorota; Rabolli, Virginie; Thomassen, Leen C J; Dinsdale, David; Princen, Catherine; Gonzalez, Laetitia; Poels, Katrien L C; Kirsch-Volders, Micheline; Lison, Dominique; Martens, Johan A; Hoet, Peter H

    2012-04-16

    Amorphous silica nanoparticles (SiO₂-NPs) have found broad applications in industry and are currently intensively studied for potential uses in medical and biomedical fields. Several studies have reported cytotoxic and inflammatory responses induced by SiO₂-NPs in different cell types. The present study was designed to examine the association of oxidative stress markers with SiO₂-NP induced cytotoxicity in human endothelial cells. We used pure monodisperse amorphous silica nanoparticles of two sizes (16 and 60 nm; S16 and S60) and a positive control, iron-doped nanosilica (16 nm; SFe), to study the generation of hydroxyl radicals (HO·) in cellular-free conditions and oxidative stress in cellular systems. We investigated whether SiO₂-NPs could influence intracellular reduced glutathione (GSH) and oxidized glutathione (GSSG) levels, increase lipid peroxidation (malondialdehyde (MDA) and 4-hydroxyalkenal (HAE) concentrations), and up-regulate heme oxygenase-1 (HO-1) mRNA expression in the studied cells. None of the particles, except SFe, produced ROS in cell-free systems. We found significant modifications for all parameters in cells treated with SFe nanoparticles. At cytotoxic doses of S16 (40-50 μg/mL), we detected weak alterations of intracellular glutathione (4 h) and a marked induction of HO-1 mRNA (6 h). Cytotoxic doses of S60 elicited similar responses. Preincubation of cells being exposed to SiO₂-NPs with an antioxidant (5 mM N-acetylcysteine, NAC) significantly reduced the cytotoxic activity of S16 and SFe (when exposed up to 25 and 50 μg/mL, respectively) but did not protect cells treated with S60. Preincubation with NAC significantly reduced HO-1 mRNA expression in cells treated with SFe but did not have any effect on HO-1 mRNA level in cell exposed to S16 and S60. Our study demonstrates that the chemical composition of the silica nanoparticles is a dominant factor in inducing oxidative stress.

  2. Single Event Transients Induced by Picosecond Pulsed X-Ray Absorption in III-V Heterojunction Transistors

    SciTech Connect

    Cardoza, David M; LaLumondiere, Stephen D; Tockstein, Michael A; Witczak, Steven C; Sin, Yongkun; Foran, Brendan J; Lotshaw, William T; Moss, Steven C

    2013-01-17

    We perform measurements which show that focused, picosecond pulses of x-rays can be used to generate single event transients (SET) in a GaAs heterostructure field effect transistor (HFET) and a GaN high electron mobility transistor. X-ray pulses with photon energies of 8, 10 and 12 keV from the Advanced Photon Source at Argonne National Laboratory were used to excite transients. SETs are observed when x-ray pulses are incident upon metal layers above sensitive areas on the transistors. We use focused ion beam (FIB) cross-sectioning and scanning transmission electron microscopy energy dispersive x-ray spectroscopy (STEM-EDXS) to determine the compositional structure of the devices. We present a first order analysis of energy deposition in the devices and correlate it to the transient response to make preliminary interpretations of the results. We compare the x-ray transients from the GaAs HFET with transients generated by 750 nm and 870 nm femtosecond laser pulses. We also present results on the total dose susceptibility of the GaN HEMTs.

  3. ZnO nanoparticles induced exopolysaccharide production by B. subtilis strain JCT1 for arid soil applications.

    PubMed

    Raliya, Ramesh; Tarafdar, J C; Mahawar, H; Kumar, Rajesh; Gupta, Priya; Mathur, Tanu; Kaul, R K; Praveen-Kumar; Kalia, A; Gautam, R; Singh, S K; Gehlot, H S

    2014-04-01

    ZnO nanoparticle induced exopolysaccharide (EPS) production from Bacillus subtilis strain JCT1 (NCBI GenBank Accession No. JN194187) is a novel approach for arid soil applications. In the series of investigations, environmentally benign protocol was followed for the synthesis of ZnO nanoparticles using extracellular enzymes obtained from Aspergillus fumigatus TFR8. Putative characterization techniques were employed for confirmation of size, shape, surface structure, crystalline nature and elemental proportion of ZnO nanoparticles. Results established an average size of ZnO nanoparticles to be 2.9 nm at least at one dimension and oblate spherical in structure. The qualitative composition of the nanoparticles exhibited 97.5% Zn element atom percentage. Biosynthesized ZnO nanoparticles enhanced exopolysaccharide production by 596.1% as compared to control and further EPS amelioration led to enhanced soil aggregation (up to 82%), moisture retention (10.7-14.2%) and soil organic carbon. Soil aggregation stability was further confirmed by Fourier transform infra-red spectroscopy. A possible ZnO nanoparticle mediated biological mechanism for enhancing exopolysaccharide production has been discussed.

  4. Iron nanoparticle growth induced by Kr-F excimer laser photolysis of Fe(CO)5

    NASA Astrophysics Data System (ADS)

    Eremin, A. V.; Gurentsov, E. V.; Priemchenko, K. Yu

    2013-06-01

    In this article the process of nanoparticle formation under the condensation of highly supersaturated atomic vapor produced by the photodissociation of metal-bearing compounds was investigated. The iron nanoparticles were synthesized by Kr-F laser pulse photolysis of Fe(CO)5. The measurements of an optical density of condensed phase were performed using a laser light extinction at a wavelength 633 nm. The particle size during their formation process was measured by a two-color time-resolved laser-induced incandescence. The final iron particle sizes and their structure were analyzed by a transmission electron microscopy. It has been shown that the process of iron particle formation in the investigated conditions could be divided onto three stages: the fast nucleation of iron atoms during 1-2 μs, the surface growth of particles up to the sizes of 1-6 nm with increasing volume fraction of condensed phase during 100-250 μs, and the relatively slow particle coagulation up to the final sizes of 5-9 nm. The effective rate constants of iron clusters and particle growth were extracted using laser light extinction measurements. The essential role of the reactions of iron clusters and particles with the parental Fe(CO)5 molecules was established. The kinetic mechanism of iron nanoparticle growth induced by photo-dissociation of Fe(CO)5 at room temperature based on obtained experimental results and known literature data has been suggested. The results obtained could be used for the developments of methods of synthesis of catalysts, magnetic nanopowders, and others nanomaterials at room temperature. Besides that, the presented experimental data could be useful for the validation of kinetic models of gas-phase condensation of supersaturated vapor of solids.

  5. Bacopa monniera Stabilized Silver Nanoparticles Attenuates Oxidative Stress Induced by Aluminum in Albino Mice.

    PubMed

    Mahitha, B; Deva Prasad Raju, B; Mallikarjuna, K; Durga Mahalakshmi, Ch N; Sushmal, N John

    2015-02-01

    In the recent years usage of nanomedicine plays a promising strategy in the improvement of medical treatment. The ecofriendly synthesized silver nanoparticles has introduced a new opportunity to increase the efficacy of drug by reducing its side effects. In the present study, we investigated the antioxidant property of Bacopa monniera stabilized silver nanoparticles against aluminum induced toxicity in albino mice. Forty male albino mice were randomly divided into five groups. First group was treated as control, second group received aluminum acetate (5 mg/kg b . w), third group received Bacopa monniera extract (5 mg/kg b . w), fourth group received BmSNPs (5 mg/kg b . w), fifth group received aluminum acetate plus BmSNPs. Exposure to aluminum acetate significantly increased lipid peroxidation levels with a significant decrease in the antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase activities in the brain, liver and kidney of mice. Degenerative changes were also observed in brain, liver and kidney of aluminum treated mice. No significant changes in the oxidative stress were observed in the Bacopa monniera and BmSNPs alone treated mice. Whereas, co-administration of BmSNPs to Al treated mice showed a significant decrease in lipid peroxidation levels with a significant increase of SOD, CAT and GPx indicating the antioxidant potential of nanoparticles and in counteracting Al induced oxidative stress and histological response in male albino mice. These findings clearly implicate that BmSNPs are able to eradicate the oxidative stress and prevent the tissue damage in aluminum exposed mice.

  6. Influence of Hepes- and CO2/HCO(3-)-buffer on Ca2+ transients induced by TRH and elevated K+ in rat pituitary GH4C1 cells.

    PubMed

    Törnquist, K; Päällysaho, J; Heinonen, E; Kaila, K

    1995-07-01

    The influence of two buffer systems (Hepes and CO2/HCO3-) on intracellular Ca2+ ([Ca2+]i) transients evoked by TRH and by elevated K+ were studied in single, and small clusters of, clonal rat pituitary GH4C1 cells using Fura 2. The steady-state level of [Ca2+]i was virtually identical in Hepes and CO2/HCO3-. In both buffers, addition of TRH induced a transient increase in [Ca2+]i which attained a significantly higher peak in Hepes (357 +/- 43 nM) when compared with values measured in the presence of CO2/HCO3- (184 +/- 21 nM). In Hepes, the basal IP3-level was higher than in CO2/HCO3-. The TRH-evoked increase in IP3 was higher in magnitude in Hepes than in CO2/HCO3-, although the stimulated/basal ratio was not different between the two buffers. The buffer composition had no effect on the specific binding of 3H-TRH to the cells. Furthermore, the amplitude of the increase in [Ca2+]i evoked by 50 mM K+ was identical in both buffers. TRH and K+ had no effect on pHi in either buffer. The present results indicate that HCO3- has an influence on TRH-induced Ca2+ transient, at least in part by modifying the TRH-evoked production of IP3.

  7. Cerium oxide nanoparticles protect primary mouse bone marrow stromal cells from apoptosis induced by oxidative stress

    NASA Astrophysics Data System (ADS)

    Zhang, Qun; Ge, Kun; Duan, Jianlei; Chen, Shizhu; Zhang, Ran; Zhang, Cuimiao; Wang, Shuxiang; Zhang, Jinchao

    2014-11-01

    Cerium oxide nanoparticles (nanoceria) have been widely used in industries and biomedical fields due to its unique properties. Previous biodistribution studies of nanoceria in vivo have shown that they are accumulated in the bone of mice after intravenous administration, about 20 % of the total intake, however, the potential effect and the mechanism of nanoceria on bone metabolism are not well-understood. Our results showed that both 25 and 50 nm nanceria decreased the damage of cell viability induced by H2O2 in a dose-dependent manner. The apoptosis ratio of pre-incubated group with nanoceria was lower than the H2O2 group. The cellular uptake studies indicated that there was a dose-dependent accumulation of both two size nanoparticles in bone marrow stromal cells. Nanoceria could be uptaken by cells due to the synergistic effect of multiple endocytosis mechanisms, and then evenly distributed in the cytoplasm without entering the nucleus. Our results suggest that nanoceria could reduce intracellular ROS level induced by H2O2 in a dose-dependent manner, moreover, maintain the normal function of mitochondria, suggesting nanoceria may have potent applications for preventing or treating osteoporosis.

  8. Analysis of the activation routes induced by different metal oxide nanoparticles on human lung epithelial cells

    PubMed Central

    Simón-Vázquez, Rosana; Lozano-Fernández, Tamara; Dávila-Grana, Angela; González-Fernández, África

    2016-01-01

    Nanoparticles (Nps) can induce toxicity in the lung by accidental or intentional exposure. The main objective of the study reported here was to characterize the effect that four metal oxide Nps (CeO2, TiO2, Al2O3 and ZnO) had at the cellular level on a human lung epithelial cell line. This goal was achieved by studying the capacity of the Nps to activate the main mitogen-activated protein kinases (MAPKs) and the nuclear factor NFκB. Only ZnO Nps were able to activate all of the MAPKs and the release of Zn2+ ions was the main cause of activation. ZnO and Al2O3 Nps activated the NFκB pathway and induced the release of inflammatory cytokines. CeO2 and TiO2 Nps were found to have safer profiles. The graphical abstract was obtained using Servier Medical Art. PMID:28031965

  9. Controllable assembly of silver nanoparticles induced by femtosecond laser direct writing.

    PubMed

    Wang, Huan; Liu, Sen; Zhang, Yong-Lai; Wang, Jian-Nan; Wang, Lei; Xia, Hong; Chen, Qi-Dai; Ding, Hong; Sun, Hong-Bo

    2015-04-01

    We report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ∼190 nm. Taking advantage of the 'direct writing' feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices.

  10. Quantum Mode Selectivity of Plasmon-Induced Water Splitting on Gold Nanoparticles.

    PubMed

    Yan, Lei; Wang, Fangwei; Meng, Sheng

    2016-05-24

    Plasmon induced water splitting is a promising research area with the potential for efficient conversion of solar to chemical energy, yet its atomic mechanism is not well understood. Here, ultrafast electron-nuclear dynamics of water splitting on gold nanoparticles upon exposure to femtosecond laser pulses was directly simulated using real time time-dependent density functional theory (TDDFT). Strong correlation between laser intensity, hot electron transfer, and reaction rates has been identified. The rate of water splitting is dependent not only on respective optical absorption strength, but also on the quantum oscillation mode of plasmonic excitation. Odd modes are more efficient than even modes, owing to faster decaying into hot electrons whose energy matches well the antibonding orbital of water. This finding suggests photocatalytic activity can be manipulated by adjusting the energy level of plasmon-induced hot carriers, through altering the cluster size and laser parameter, to better overlap adsorbate unoccupied level in plasmon-assisted photochemistry.

  11. Sex-Dependent Depression-Like Behavior Induced by Respiratory Administration of Aluminum Oxide Nanoparticles.

    PubMed

    Zhang, Xin; Xu, Yan; Zhou, Lian; Zhang, Chengcheng; Meng, Qingtao; Wu, Shenshen; Wang, Shizhi; Ding, Zhen; Chen, Xiaodong; Li, Xiaobo; Chen, Rui

    2015-12-09

    Ultrafine aluminum oxide, which are abundant in ambient and involved occupational environments, are associated with neurobehavioral alterations. However, few studies have focused on the effect of sex differences following exposure to environmental Al₂O₃ ultrafine particles. In the present study, male and female mice were exposed to Al₂O₃ nanoparticles (NPs) through a respiratory route. Only the female mice showed depression-like behavior. Although no obvious pathological changes were observed in mice brain tissues, the neurotransmitter and voltage-gated ion channel related gene expression, as well as the small molecule metabolites in the cerebral cortex, were differentially modulated between male and female mice. Both mental disorder-involved gene expression levels and metabolomics analysis results strongly suggested that glutamate pathways were implicated in sex differentiation induced by Al₂O₃ NPs. Results demonstrated the potential mechanism of environmental ultrafine particle-induced depression-like behavior and the importance of sex dimorphism in the toxic research of environmental chemicals.

  12. The Influence of Supporting Ions on the Electrochemical Detection of Individual Silver Nanoparticles: Understanding the Shape and Frequency of Current Transients in Nano-impacts.

    PubMed

    Krause, Kay J; Brings, Fabian; Schnitker, Jan; Kätelhön, Enno; Rinklin, Philipp; Mayer, Dirk; Compton, Richard G; Lemay, Serge G; Offenhäusser, Andreas; Wolfrum, Bernhard

    2017-04-03

    We report the influence of electrolyte composition and concentration on the stochastic amperometric detection of individual silver nanoparticles at microelectrode arrays and show that the sensor response at certain electrode potentials is dependent on both the conductivity of the electrolyte and the concentration of chloride ions. We further demonstrate that the chloride concentration in solution heavily influences the characteristic current spike shape of recorded nanoparticle impacts: While typically too short to be resolved in the measured current, the spike widths are significantly broadened at low chloride concentrations below 10 mm and range into the millisecond regime. The analysis of more than 25 000 spikes reveals that this effect can be explained by the diffusive mass transport of chloride ions to the nanoparticle, which limits the oxidation rate of individual silver nanoparticles to silver chloride at the chosen electrode potential.

  13. Very virulent plus strains of MDV induce an acute form of transient paralysis in both susceptible and resistant chicken lines.

    PubMed

    Xu, Ming; Fitzgerald, Scott D; Zhang, Huanmin; Karcher, Darrin M; Heidari, Mohammad

    2012-08-01

    Marek's disease (MD) is a lymphoproliferative disease of domestic chickens caused by a highly cell-associated alpha herpesvirus, Marek's disease virus (MDV). Clinical signs of MD include depression, crippling, weight loss, and transient paralysis (TP). TP is a disease of the central nervous system that affects MD-susceptible chickens 8-11 days post-infection (dpi), normally resulting in recovery 1-3 d after the onset of clinical signs. In this study we inoculated chickens from lines 7(2) (MD-susceptible) and 6(3) (MD-resistant) with a very virulent plus strain of MDV at 2 wk of age, and collected brain samples from birds with and without TP at 5, 11, and 21 dpi for gene expression profiling and histological analysis. Data revealed that chickens inoculated with MDV had higher levels of IL-6, IL-10, IL-18, IFN-α, IFN-β, IFN-γ, MHC I, and CD18 in their brains at 11 dpi compared to the uninfected control birds. In addition, the expression levels of IL-6, IL-10, IFN-α, IFN-β, and IFN-γ were significantly higher in the brains of the birds showing clinical signs of TP than in asymptomatic chickens. Comparative analysis between the two chicken lines showed that the expression levels of IL-6, IL-10, IFN-β, IFN-γ, IL-18, CD18, and MHC I were significantly higher in the brains of the birds from line 6(3) with TP than those of line 7(2) exhibiting neurological disorders. A differential expression pattern was observed for some of the tested genes at different time points post-inoculation. Histological analysis showed lymphocytic meningitis, perivascular cuffing, and neuronal degeneration within the brains of birds from both susceptible and resistant lines exhibiting TP at 11 dpi. Vaccination prevented development of TP and other MD-associated clinical symptoms. These observations are suggestive of an underlying immunological mechanism for viral-induced neurological dysfunction, and the differential responses of the two chicken lines to MDV infection.

  14. DNA strand breaks and crosslinks induced by transient anions in the range 2-20 eV

    NASA Astrophysics Data System (ADS)

    Luo, Xinglan; Zheng, Yi; Sanche, Léon

    2014-04-01

    The energy dependence of the yields of single and double strand breaks (SSB and DSB) and crosslinks induced by electron impact on plasmid DNA films is measured in the 2-20 eV range. The yield functions exhibit two strong maxima, which are interpreted to result from the formation of core-excited resonances (i.e., transient anions) of the bases, and their decay into the autoionization channel, resulting in π → π* electronic transitions of the bases followed by electron transfer to the C-O σ* bond in the phosphate group. Occupancy of the σ* orbital ruptures the C-O bond of the backbone via dissociative electron attachment, producing a SSB. From a comparison of our results with those of other works, including theoretical calculations and electron-energy-loss spectra of the bases, the 4.6 eV peak in the SSB yield function is attributed to the resonance decay into the lowest electronically excited states of the bases; in particular, those resulting from the transitions 13A' (π2 → π3*) and 13A″ (n2 → π3*) of thymine and 13A' (π → π*) of cytosine. The strongest peak at 9.6 eV in the SSB yield function is also associated with electron captured by excited states of the bases, resulting mostly from a multitude of higher-energy π → π* transitions. The DSB yield function exhibits strong maxima at 6.1 and 9.6 eV. The peak at 9.6 eV is probably related to the same resonance manifold as that leading to SSB, but the other at 6.1 eV may be more restricted to decay into the electronic state 13A' (π → π*) of cytosine via autoionization. The yield function of crosslinks is dominated by a broad peak extending over the 3.6-11.6 eV range with a sharper one at 17.6 eV. The different line shape of the latter function, compared to that of SSB and DSB, appears to be due to the formation of reactive radical sites in the initial supercoiled configuration of the plasmid, which react with the circular form (i.e., DNA with a SSB) to produce a crosslink.

  15. Blast Overpressure Waves Induce Transient Anxiety and Regional Changes in Cerebral Glucose Metabolism and Delayed Hyperarousal in Rats.

    PubMed

    Awwad, Hibah O; Gonzalez, Larry P; Tompkins, Paul; Lerner, Megan; Brackett, Daniel J; Awasthi, Vibhudutta; Standifer, Kelly M

    2015-01-01

    Physiological alterations, anxiety, and cognitive disorders are strongly associated with blast-induced traumatic brain injury (blast TBI), and are common symptoms in service personnel exposed to blasts. Since 2006, 25,000-30,000 new TBI cases are diagnosed annually in U.S. Service members; increasing evidence confirms that primary blast exposure causes diffuse axonal injury and is often accompanied by altered behavioral outcomes. Behavioral and acute metabolic effects resulting from blast to the head in the absence of thoracic contributions from the periphery were examined, following a single blast wave directed to the head of male Sprague-Dawley rats protected by a lead shield over the torso. An 80 psi head blast produced cognitive deficits that were detected in working memory. Blast TBI rats displayed increased anxiety as determined by elevated plus maze at day 9 post-blast compared to sham rats; blast TBI rats spent significantly more time than the sham controls in the closed arms (p < 0.05; n = 8-11). Interestingly, anxiety symptoms were absent at days 22 and 48 post-blast. Instead, blast TBI rats displayed increased rearing behavior at day 48 post-blast compared to sham rats. Blast TBI rats also exhibited suppressed acoustic startle responses, but similar pre-pulse inhibition at day 15 post-blast compared to sham rats. Acute physiological alterations in cerebral glucose metabolism were determined by positron emission tomography 1 and 9 days post-blast using (18)F-fluorodeoxyglucose ((18)F-FDG). Global glucose uptake in blast TBI rat brains increased at day 1 post-blast (p < 0.05; n = 4-6) and returned to sham levels by day 9. Our results indicate a transient increase in cerebral metabolism following a blast injury. Markers for reactive astrogliosis and neuronal damage were noted by immunoblotting motor cortex tissue from day 10 post-blast in blast TBI rats compared to sham controls (p < 0.05; n = 5-6).

  16. Impulsion of nanoparticles as a drug carrier for the theoretical investigation of stenosed arteries with induced magnetic effects

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Ijaz, S.

    2016-07-01

    In this paper hemodynamics of stenosis are discussed to predict effect of atherosclerosis by means of mathematical models in the presence of uniform transverse magnetic field. The analysis is carried out using silver and copper nanoparticles as a drug carrier. Exact solution for the fluid temperature, velocity, axial induced magnetic field and current density distribution are obtained under mild stenosis approximation. The results indicate that with an increase in the concentration of nanoparticle hemodynamics effects of stenosis reduces throughout the inclined composite stenosed arteries. The considered analysis also summarizes that the drug silver nanoparticles is more efficient to reduce hemodynamics of stenosis when compare to the drug copper nanoparticle. In future this model could be helpful to predict important properties in some biomedical applications.

  17. Durable, superoleophobic polymer–nanoparticle composite surfaces with re-entrant geometry via solvent-induced phase transformation

    NASA Astrophysics Data System (ADS)

    Brown, Philip S.; Bhushan, Bharat

    2016-02-01

    Superoleophobic plastic surfaces are useful in a wide variety of applications including anti-fouling, self-cleaning, anti-smudge, and low-drag. Existing examples of superoleophobic surfaces typically rely on poorly adhered coatings or delicate surface structures, resulting in poor mechanical durability. Here, we report a facile method for creating re-entrant geometries desirable for superoleophobicity via entrapment of nanoparticles in polycarbonate surfaces. Nanoparticle incorporation occurs during solvent-induced swelling and subsequent crystallization of the polymer surface. The resulting surface was found to comprise of re-entrant structures, a result of the nanoparticle agglomerates acting as nucleation points for polymer crystallization. Examples of such surfaces were further functionalized with fluorosilane to result in a durable, super-repellent surface. This method of impregnating nanoparticles into polymer surfaces could prove useful in improving the anti-bacterial, mechanical, and liquid-repellent properties of plastic devices.

  18. Durable, superoleophobic polymer–nanoparticle composite surfaces with re-entrant geometry via solvent-induced phase transformation

    PubMed Central

    Brown, Philip S.; Bhushan, Bharat

    2016-01-01

    Superoleophobic plastic surfaces are useful in a wide variety of applications including anti-fouling, self-cleaning, anti-smudge, and low-drag. Existing examples of superoleophobic surfaces typically rely on poorly adhered coatings or delicate surface structures, resulting in poor mechanical durability. Here, we report a facile method for creating re-entrant geometries desirable for superoleophobicity via entrapment of nanoparticles in polycarbonate surfaces. Nanoparticle incorporation occurs during solvent-induced swelling and subsequent crystallization of the polymer surface. The resulting surface was found to comprise of re-entrant structures, a result of the nanoparticle agglomerates acting as nucleation points for polymer crystallization. Examples of such surfaces were further functionalized with fluorosilane to result in a durable, super-repellent surface. This method of impregnating nanoparticles into polymer surfaces could prove useful in improving the anti-bacterial, mechanical, and liquid-repellent properties of plastic devices. PMID:26876479

  19. Application of magnetic and core-shell nanoparticles to determine enrofloxacin and its metabolite using laser induced fluorescence microscope.

    PubMed

    Kim, Suji; Ko, Junga; Lim, H B

    2013-04-10

    A unique analytical method using nanoparticles and laser-induced fluorescence microscopy (LIFM) was developed to determine enrofloxacin in this work. For sample pretreatment, two different kinds of particles, i.e., synthesized dye-doped core-shell silica nanoparticles and magnetic micro-particles (MPs), were used for fluorescent tagging and concentrating the enrofloxacin, respectively. The antibody of enrofloxacin was immobilized on the synthesized FITC-doped core-shell nanoparticles, and the enrofloxacin target was extracted by the MPs. At this moment, the average number of antibodies on each core-shell silica nanoparticle was ~0.9, which was determined by the fluorescence ratiometric method. The described method was demonstrated for a meat sample to determine enrofloxacin using LIFM, and the result was compared with enzyme-linked immunosorbent assay (ELISA). The developed technique allowed the simplified analytical procedure, improved the detection limit about 54-fold compared to ELISA.

  20. Effect of glycyrrhizic acid on titanium dioxide nanoparticles-induced hepatotoxicity in rats.

    PubMed

    Orazizadeh, Mahmoud; Fakhredini, Fereshtesadat; Mansouri, Esrafil; Khorsandi, Layasadat

    2014-09-05

    Many recent studies demonstrate that most nanoparticles (NPs) have an adverse or toxic action on liver. The aim of this study was to investigate the hepatoprotective effect of glycyrrhizic acid (GA) against hepatic injury induced by titanium dioxide nanoparticles (NTiO2) in rats. Thirty-two Wistar rats were randomly divided into 4 groups. NTiO2-intoxicated rats received 300 mg/kg of NTiO2 for 14 days by gavage method. Protection group pretreated with GA for 7 days before NTiO2 administration. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were detected as biomarkers in the blood to indicate hepatic injury. Product of lipid peroxidation (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPx) were evaluated for oxidative stress in hepatic injury. Light microscopy for histopathological studies and TUNEL assay was also done. Administration of NTiO2 induced a significant elevation in plasma AST, ALT and ALP. In the liver, NTiO2 increased oxidative stress through the increase in lipid peroxidation and decrease in SOD and GPx enzymes. Histopathological studies showed that treatment with NTiO2 caused liver damage including centrilobular necrosis, which was accompanied by congestion and accumulation of inflammatory cells. Apoptotic index was also significantly increased in this group. Pretreatment of GA significantly decreased ALT, AST and ALP, attenuated the histopathology of hepatic injury, decreased apoptotic index, ameliorated oxidative stress in hepatic tissue, and increased the activities of SOD and GPx. These findings indicate that GA effectively protects against NTiO2-induced hepatotoxicity. GA has a potent protective effect against the NPs induced hepatotoxicity and might be clinically useful.

  1. Anti-inflammatory effect of selenium nanoparticles on the inflammation induced in irradiated rats.

    PubMed

    El-Ghazaly, M A; Fadel, N; Rashed, E; El-Batal, A; Kenawy, S A

    2017-02-01

    Selenium (Se) has been reported to possess anti-inflammatory properties, but its bioavailability and toxicity are considerable limiting factors. The present study aimed to investigate the possible anti-inflammatory and analgesic effects of selenium nanoparticles (Nano-Se) on inflammation induced in irradiated rats. Paw volume and nociceptive threshold were measured in carrageenan-induced paw edema and hyperalgesia model. Leukocytic count, tumor necrosis factor-α (TNF-α), prostaglandin E2 (PGE2), thiobarbituric acid reactive substances (TBAR), and total nitrate/nitrite (NOx) were estimated in the exudate collected from 6 day old air pouch model. Irradiated rats were exposed to 6 Gy gamma (γ)-irradiation. Nano-Se were administered orally in a dose of 2.55 mg/kg once before carrageenan injection in the first model and twice in the second model. The paw volume but not the nociceptive response produced by carrageenan in irradiated rats was higher than that induced in non-irradiated rats. Nano-Se were effective in reducing the paw volume in non-irradiated and irradiated rats but it did not alter the nociceptive threshold. The inflammation induced in irradiated rats increased all the estimated parameters in the exudate whereas; Nano-Se decreased their elevation in non-irradiated and irradiated rats. Nano-Se possess a potential anti-inflammatory activity on inflammation induced in irradiated rats.

  2. Effects of fullerenol nanoparticles on acetamiprid induced cytoxicity and genotoxicity in cultured human lung fibroblasts.

    PubMed

    Çavaş, Tolga; Çinkılıç, Nilüfer; Vatan, Özgür; Yılmaz, Dilek

    2014-09-01

    The aim of this study was to investigate the effects of water soluble fullerene (fullerenol) nanoparticles on the in vitro genotoxicity induced by the insecticide acetamiprid. Healthy human lung cells (IMR-90) were treated with fullerenol C60(OH)n (n: 18-22) alone and in combination with acetamiprid for 24h. The micronucleus test, comet assay and γ-H2AX foci formation assays were used as genotoxicity endpoints. Cytotoxicity was evaluated using the clonogenic assay. The maximum tested concentration of fullerenol (1.600 μg/ml) induced 77% survival where as the lowest concentration (25 μg/ml) was not cytotoxic where as acetamiprid was cytotoxic. Fullerenol did not induce genotoxicity at tested concentrations (50-1600 μg/L). On the other hand, acetamiprid (>50 μM) significantly induced formation of micronuclei, and double and single stranded DNA breaks in IMR-90 cells. For simultaneous exposure studies, two non-cytotoxic concentrations (50 and 200 μg/ml) of fullerenol and three cytotoxic concentrations of acetamiprid (100, 200 and 400 μM) were selected. As a result, we observed that co-exposure with fullerenol significantly reduced the cytotoxicity and genotoxicity of acetamiprid in IMR-90 cells. Our results indicated the protective effect of water soluble fullerene particles on herbicide induced genotoxicity.

  3. Egr1 is rapidly and transiently induced by estrogen and bisphenol A via activation of nuclear estrogen receptor-dependent ERK1/2 pathway in the uterus.

    PubMed

    Kim, Hye-Ryun; Kim, Yeon Sun; Yoon, Jung Ah; Lyu, Sang Woo; Shin, Hyejin; Lim, Hyunjung J; Hong, Seok-Ho; Lee, Dong Ryul; Song, Haengseok

    2014-12-01

    Coordinate actions of ovarian estrogen (E2) and progesterone (P4) via their own receptors are critical for establishing uterine receptivity for embryo implantation in the uterus. E2 regulates expression of an array of genes to mediate its major actions on heterogeneous uterine cell types. Here we have investigated regulatory mechanism(s) of E2 and bisphenol A (BPA), an endocrine disruptor with potent estrogenic activity on expression of early growth response 1 (Egr1), a zinc finger transcription factor that regulates cell growth, differentiation and apoptosis in the uterus. Egr1 was rapidly and transiently induced by E2 and BPA mainly in stromal cells via nuclear estrogen receptor (ER)-ERK1/2 pathway. ICI 182,780, an ER antagonist, effectively inhibited their actions on EGR1 expression following ERK1/2 phosphorylation. Administration of pharmacological inhibitors for ERK1/2, but not AKT significantly blocked EGR1 expression induced by E2 and BPA. P4 effectively dampened action(s) of E2 and BPA on Egr1 expression via nuclear progesterone receptor. Its antagonistic effects were partially interfered with RU486 pretreatment. Interestingly, EGR1 is specifically induced in stromal cells surrounding implanting blastocyst. Collectively, our results show that through nuclear ER-dependent ERK1/2 phosphorylation, not only E2 but also endocrine disruptors with estrogenic activity such as BPA rapidly and transiently induce Egr1 which may be important for embryo implantation and decidualization in mouse uterus.

  4. Improved microbial growth inhibition activity of bio-surfactant induced Ag-TiO2 core shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Nithyadevi, D.; Kumar, P. Suresh; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.; Meena, P.

    2015-02-01

    Surfactant induced silver-titanium dioxide core shell nanoparticles within the size range of 10-50 nm were applied in the antibacterial agent to inhibit the growth of bacterial cells. The single crystalline silver was located in the core part of the composite powder and the titanium dioxide components were uniformly distributed in the shell part. HRTEM and XRD results indicated that silver was completely covered by titanium dioxide and its crystal structure was not affected after being coated by titanium dioxide. The effect of silver-titanium dioxide nanoparticles in the inhibition of bacterial cell growth was studied by means of disk diffusion method. The inhibition zone results reveal that sodium alginate induced silver-titanium dioxide nanoparticles exhibit 100% more antibacterial activity than that with cetyltrimethylbromide or without surfactant. UV-vis spectroscopic analysis showed a large concentration of silver was rapidly released into phosphate buffer solution (PBS) within a period of 1 day, with a much smaller concentration being released after this 1-day period. It was concluded that sodium alginate induced silver-titanium dioxide core shell nanoparticles could enhance long term cell growth inhibition in comparison with cetyltrimethylbromide or without surfactant. The surfactant mediated core shell nanoparticles have comparatively rapid, less expensive and wider applications in modern antibacterial therapy.

  5. Phoxim-induced damages of Bombyx mori larval midgut and titanium dioxide nanoparticles protective role under phoxim-induced toxicity.

    PubMed

    Su, Junju; Li, Bing; Cheng, Shen; Zhu, Zhou; Sang, Xuezi; Gui, Suxin; Xie, Yi; Sun, Qingqing; Cheng, Zhe; Cheng, Jie; Hu, Rengping; Shen, Weide; Xia, Qingyou; Zhao, Ping; Hong, Fashui

    2014-12-01

    Phoxim (O,O-diethyl O-(alpha-cyanobenzylideneamino) phosphorothioate) is a powerful organophosphorus pesticide with high potential for Bombyx mori larvae of silkworm exposure. However, it is possible that during the phoxim metabolism, there is generation of reactive oxygen species (ROS) and phoxim may produce oxidative stress and neurotoxicity in an intoxicated silkworm. Titanium dioxide nanoparticles (TiO2 NPs) pretreatment has been demonstrated to increase antioxidant capacity and acetylcholinesterase (AChE) activity in organisms. This study was, therefore, undertaken to determine phoxim-induced oxidative stress and neurotoxicity to determine whether phoxim intoxication alters the antioxidant system and AChE activity in the B. mori larval midgut, and to determine whether TiO2 NPs pretreatment attenuates phoxim-induced toxicity. The findings suggested that phoxim exposure decreased survival of B. mori larvae, increased malondialdehyde (MDA), carbonyl and 8-OHdG levels, and ROS accumulation in the midgut. Furthermore, phoxim significantly decreased the activities of AChE, superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione-S-transferase (GST), and levels of ascorbic acid (AsA), reduced glutathione (GSH), and thiol in the midgut. TiO2 pretreatment, however, could increase AChE activity, and remove ROS via activating SOD, CAT, APX, GR, and GST, and accelerating AsA-GSH cycle, thus attenuated lipid, protein, and DNA peroxidation and improve B. mori larval survival under phoxim-induced toxicity. Moreover, this experimental system would help nanomaterials to be applied in the sericulture.

  6. Efficiency Of The Photodynamic Therapy Using Gold Nanoparticles (np-Au) And PpIX Induced And Not Induced

    SciTech Connect

    Maldonado-Alvarado, Elizabeth; Ramon-Gallegos, Eva; Arenas-Huertero, Francisco jesus; Reyes-Arellano, Alicia; Sanchez-Espindola, Maria Esther; Jimenez-Perez, Jose Luis; Cruz-Orea, Alfredo

    2008-08-11

    The use of gold nanoparticles (np-Au) to eliminate cancer has proved to be very effective due to the fact that cancerous cells accumulate it 600% more than healthy cells. In addition they have a high capacity of absorption and dispersion of light. Therefore, the effectiveness of photodynamic therapy (PDT) could be improved by the simultaneous use of np-Au and photosensitizes (Ps), emphasizing the high efficiency of the PDT to diagnose and to treat pre-malignant and malignant processes. The aim of this work was to determine the efficiency of PDT using np-Au and protoporphyrin IX (PpIX) induced and not induced by the {delta}-aminolevulinic acid (ALA). It were found the conditions of synthesis of hydrosoluble np-Au, and were characterized by transmission electronic microscopy (TEM) and UV-VIS spectroscopy. It was realized a kinetic by TEM to determine the cellular incorporation time of np-Au, the maximum incorporation of np-Au was of 16 h. PDT was applied using different doses of np-Au and photosensitizers. It was observed that the use of PDT simultaneously with np-Au did not increase the mortality of HeLa cells. In the case of C33, when PpIX not induced is used as photosensitizer simultaneously with np-Au, the mortality increased 20%.

  7. Very virulent plus strains of MDV induce acute form of transient paralysis in both susceptible and resistant chicken lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marek’s Disease (MD) is a lymphoproliferative disease of domestic chickens caused by a highly cell-associated alpha herpesvirus, Marek’s disease virus (MDV). Clinical signs of MD include depression, crippling, weight loss, and transient paralysis (TP). TP is a disease of the central nervous system...

  8. Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers

    PubMed Central

    Rückriem, Kai; Grotheer, Sarah; Vieker, Henning; Penner, Paul; Beyer, André; Gölzhäuser, Armin

    2016-01-01

    Summary Copper(II) oxalate grown on carboxy-terminated self-assembled monolayers (SAM) using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II) acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II) oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS). Helium ion microscopy (HIM) reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS) confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor. PMID:27547602

  9. Cytotoxicity and genotoxicity in liver cells induced by cobalt nanoparticles and ions

    PubMed Central

    Liu, Y. K.; Deng, X. X.

    2016-01-01

    Objectives The cytotoxicity induced by cobalt ions (Co2+) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co2+ and Co-NPs on liver cells, and explain further the potential mechanisms. Methods Co-NPs were characterised for size, shape, elemental analysis, and hydrodynamic diameter, and were assessed by Transmission Electron Microscope, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy and Dynamic Light Scattering. BRL-3A cells were used in this study. Cytotoxicity was evaluated by MTT and lactate dehydrogenase release assay. In order to clarify the potential mechanisms, reactive oxygen species, Bax/Bcl-2 mRNA expression, IL-8 mRNA expression and DNA damage were assessed on BRL-3A cells after Co2+ or Co-NPs treatment. Results Results showed cytotoxic effects of Co2+ and Co-NPs were dependent upon time and dosage, and the cytotoxicity of Co-NPs was greater than that of Co2+. In addition, Co-NPs elicited a significant (p < 0.05) reduction in cell viability with a concomitant increase in lactic dehydrogenase release, reactive oxygen species generation, IL-8 mRNA expression, Bax/Bcl-2 mRNA expression and DNA damage after 24 hours of exposure. Conclusion Co-NPs induced greater cytotoxicity and genotoxicity in BRL-3A cells than Co2+. Cell membrane damage, oxidative stress, immune inflammation and DNA damage may play an important role in the effects of Co-NPs on liver cells. Cite this article: Y. K. Liu, X. X. Deng, H.L. Yang. Cytotoxicity and genotoxicity in liver cells induced by cobalt nanoparticles and ions. Bone Joint Res 2016;5:461–469. DOI: 10.1302/2046-3758.510.BJR-2016-0016.R1. PMID:27754833

  10. Gold nanoparticle-filled biodegradable photopolymer scaffolds induced muscle remodeling: in vitro and in vivo findings.

    PubMed

    Zsedenyi, Adam; Farkas, Balazs; Abdelrasoul, Gaser N; Romano, Ilaria; Gyukity-Sebestyen, Edina; Nagy, Katalin; Harmati, Maria; Dobra, Gabriella; Kormondi, Sandor; Decsi, Gabor; Nemeth, Istvan Balazs; Diaspro, Alberto; Brandi, Fernando; Beke, Szabolcs; Buzas, Krisztina

    2017-03-01

    Therapeutic stem cell transplantation bears the promise of new directions in organ and tissue replacement, but a number of its difficulties and perils are also well known. Our goal was to develop a method of transplantation by which the transplanted cells remain confined to the transplantation site and induce favorable processes. With the help of mask-projection excimer laser stereolithography, 3D hybrid nanoscaffolds were fabricated from biodegradable, photocurable PPF:DEF resin with incorporated gold nanoparticles (Au NPs). The scaffolds were tested in vitro and in vivo in order to find out about their biocompatibility and fitness for our purposes. In vitro, macrophages and mouse autologous adipose stem cells (ASCs) were seeded over the hybrid scaffolds and non-hybrid (with Au NPs) scaffolds for 4days. The hybrid nanocomposite greater stem cell dispension and stem cell adhesion than PPF scaffolds without Au NPs, but such a difference was not seen in the case of macrophages. In vivo, stem cells, scaffoldings and scaffoldings covered in stem cells were transplanted under the back skin of mice. After 14days, blood samples were taken and the affected skin area was excised. Cytokine and chemokine profiling did not indicate elevated immunomediators in the sera of experimental animals. Interestingly, the autologous-stem-cell-seeded hybrid nanocomposite scaffold induced muscle tissue regeneration after experimental wound generation in vivo. We could not observe such stem cell-induced tissue regeneration when no scaffolding was used. We conclude that PPF:DEF resin nanoscaffolds with incorporated gold nanoparticles offer a safe and efficient alternative for the enhancement of local tissue remodeling. The results also support the idea that adipose derived stem cells are an optimal cell type for the purposes of regenerative musculoskeletal tissue engineering.

  11. Cell membrane damage and protein interaction induced by copper containing nanoparticles--importance of the metal release process.

    PubMed

    Karlsson, Hanna L; Cronholm, Pontus; Hedberg, Yolanda; Tornberg, Malin; De Battice, Laura; Svedhem, Sofia; Wallinder, Inger Odnevall

    2013-11-08

    Cu-containing nanoparticles are used in various applications in order to e.g. achieve antimicrobial activities and to increase the conductivity of fluids and polymers. Several studies have reported on toxic effects of such particles but the mechanisms are not completely clear. The aim of this study was to investigate the interactions between cell membranes and well-characterized nanoparticles of CuO, Cu metal, a binary Cu-Zn alloy and micron-sized Cu metal particles. This was conducted via in vitro investigations of the effects of the nanoparticles on (i) cell membrane damage on lung epithelial cells (A549), (ii) membrane rupture of red blood cells (hemolysis), complemented by (iii) nanoparticle interaction studies with a model lipid membrane using quartz crystal microbalance with dissipation monitoring (QCM-D). The results revealed that nanoparticles of the Cu metal and the Cu-Zn alloy were both highly membrane damaging and caused a rapid (within 1h) increase in membrane damage at a particle mass dose of 20 μg/mL, whereas the CuO nanoparticles and the micron-sized Cu metal particles showed no such effect. At similar nanoparticle surface area doses, the nano and micron-sized Cu particles showed more similar effects. The commonly used LDH (lactate dehydrogenase) assay for analysis of membrane damage was found impossible to use due to nanoparticle-assay interactions. None of the particles induced any hemolytic effects on red blood cells when investigated up to high particle concentrations (1mg/mL). However, both Cu and Cu-Zn nanoparticles caused hemoglobin aggregation/precipitation, a process that would conceal a possible hemolytic effect. Studies on interactions between the nanoparticles and a model membrane using QCM-D indicated a small difference between the investigated particles. Results of this study suggest that the observed membrane damage is caused by the metal release process at the cell membrane surface and highlight differences in reactivity between

  12. Silver nanoparticles impede phorbol myristate acetate-induced monocyte-macrophage differentiation and autophagy

    NASA Astrophysics Data System (ADS)

    Xu, Yingying; Wang, Liming; Bai, Ru; Zhang, Tianlu; Chen, Chunying

    2015-09-01

    Monocytes/macrophages are important constituents of the innate immune system. Monocyte-macrophage differentiation is not only crucial for innate immune responses, but is also related to some cardiovascular diseases. Silver nanoparticles (AgNPs) are one of the most widely used nanomaterials because of their broad-spectrum antimicrobial properties. However, the effect of AgNPs on the functions of blood monocytes is scarcely reported. Here, we report the impedance effect of AgNPs on THP-1 monocyte differentiation, and that this effect was mediated by autophagy blockade and lysosomal impairment. Firstly, AgNPs inhibit phorbol 12-myristate 13-acetate (PMA)-induced monocyte differentiation by down-regulating both expression of surface marker CD11b and response to lipopolysaccharide (LPS) stimulation. Secondly, autophagy is activated during PMA-induced THP-1 monocyte differentiation, and the autophagy inhibitor chloroquine (CQ) can inhibit this process. Thirdly, AgNPs block the degradation of the autophagy substrate p62 and induce autophagosome accumulation, which demonstrates the blockade of autophagic flux. Fourthly, lysosomal impairments including alkalization and decrease of lysosomal membrane stability were observed in AgNP-treated THP-1 cells. In conclusion, we demonstrate that the impedance of monocyte-macrophage differentiation by AgNPs is mediated by autophagy blockade and lysosomal dysfunction. Our results suggest that crosstalk exists in different biological effects induced by AgNPs.

  13. Dehydroepiandrosterone Protects Endothelial Cells against Inflammatory Events Induced by Urban Particulate Matter and Titanium Dioxide Nanoparticles

    PubMed Central

    Huerta-García, Elizabeth; Montiél-Dávalos, Angélica; Alfaro-Moreno, Ernesto; Gutiérrez-Iglesias, Gisela; López-Marure, Rebeca

    2013-01-01

    Particulate matter (PM) and nanoparticles (NPs) induce activation and dysfunction of endothelial cells characterized by inhibition of proliferation, increase of adhesion and adhesion molecules expression, increase of ROS production, and death. DHEA has shown anti-inflammatory and antioxidant properties in HUVEC activated with proinflammatory agents. We evaluated if DHEA could protect against some inflammatory events produced by PM10 and TiO2 NPs in HUVEC. Adhesion was evaluated by a coculture with U937 cells, proliferation by crystal violet staining, and oxidative stress through DCFDA and Griess reagent. PM10 and TiO2 NPs induced adhesion and oxidative stress and inhibited proliferation of HUVEC; however, when particles were added in combination with DHEA, the effects previously observed were abolished independently from the tested concentrations and the time of addition of DHEA to the cultures. These results indicate that DHEA exerts significant anti-inflammatory and antioxidative effects on the damage induced by particles in HUVEC, suggesting that DHEA could be useful to counteract the harmful effects and inflammatory diseases induced by PM and NPs. PMID:23484113

  14. Rapamycin ameliorates chitosan nanoparticle-induced developmental defects of preimplantation embryos in mice

    PubMed Central

    Choi, Yun-Jung; Gurunathan, Sangiliyandi; Kim, DaSom; Jang, Hyung Seok; Park, Woo-Jin; Cho, Ssang-Goo; Park, Chankyu; Song, Hyuk; Seo, Han Geuk; Kim, Jin-Hoi

    2016-01-01

    Chitosan nanoparticles (CSNPs) are used as drug or gene delivery vehicles. However, a detailed understanding of the effects of CSNPs on embryonic development remains obscure. Here, we show that CSNPs can be internalized into mouse blastocysts, such as the zona pellucida, the perivitelline space, and the cytoplasm. Consequently, CSNPs-induced endoplasmic reticulum (ER) stress increases both of Bip/Grp78, Chop, Atf4, Perk, and Ire1a mRNAs expression levels, and reactive oxygen species. Moreover, CSNPs show double- and multi-membraned autophagic vesicles, and lead to cell death of blastocoels. Conversely, treatment with rapamycin, which plays an important role as a central regulator of cellular proliferation and stress responses, decreased CSNPs-induced mitochondrial Ca+2 overloading, apoptosis, oxidative stress, ER stress, and autophagy. In vivo studies demonstrated that CSNPs injection has significant toxic effect on primordial and developing follicles. Notably, rapamycin rescued oxidative stress-induced embryonic defects via modulating gene expression of sirtuin and mammalian target of rapamycin. Interestingly, CSNPs treatment alters epigenetic reprogramming in mouse embryos. Overall, these observations suggest that rapamycin treatment could ameliorate CSNPs-induced developmental defects in preimplantation embryos. The data from this study would facilitate to understand the toxicity of these CSNPs, and enable the engineering of safer nanomaterials for therapeutic applications. PMID:27463007

  15. Local delivery of biodegradable pirfenidone nanoparticles ameliorates bleomycin-induced pulmonary fibrosis in mice

    NASA Astrophysics Data System (ADS)

    Trivedi, Ruchit; Redente, Elizabeth F.; Thakur, Ashish; Riches, David W. H.; Kompella, Uday B.

    2012-12-01

    Our purpose was to assess sustained delivery and enhanced efficacy of pirfenidone-loaded nanoparticles after intratracheal instillation. Poly(lactide-co-glycolide) nanoparticles containing pirfenidone (NPs) were prepared and characterized. Biodistribution of NPs and solution was assessed using LC-MS after intratracheal administration in C57Bl/6 mice at 3 and 24 h and 1 week post-administration. Efficacy was tested in C57Bl/6 mice in a bleomycin-induced pulmonary fibrosis model. Mice received 10 μg pirfenidone intratracheally in solution or NPs, once a week, for 3 weeks after bleomycin administration. Drug effects were monitored on day 28. Lung hydroxyproline content, total number of cells, and numbers of macrophages, lymphocytes, and neutrophils in bronchoalveolar lavage (BAL) were assessed. Numbers of macrophages, lymphocytes, and neutrophils were assessed in the lung as well. NPs sustained significantly higher levels of pirfenidone in the lungs and BAL at 24 h and 1 week, compared to the solution group. Pirfenidone solution and NPs significantly reduced hydroxyproline levels by 57 and 81%, respectively, compared to bleomycin alone. At the end of 4 weeks, BAL cellularity was reduced by 25.4% and 56% with solution and NP treatment, respectively. The numbers of lymphocytes and neutrophils in the BAL were also reduced by 58.9 and 82.4% for solution and 74.5% and 89.7% for NPs, respectively. The number of inflammatory macrophages in the lung was reduced by 62.8% and the number of neutrophils was reduced by 59.1% in the NP group and by 37.7% and 44.5%, respectively, in the solution group, compared to bleomycin alone. In conclusion, nanoparticles sustain lung pirfenidone delivery and enhance its anti-fibrotic efficacy.

  16. Surface plasmon resonance-induced visible light photocatalytic reduction of graphene oxide: using Ag nanoparticles as a plasmonic photocatalyst.

    PubMed

    Wu, Tongshun; Liu, Sen; Luo, Yonglan; Lu, Wenbo; Wang, Lei; Sun, Xuping

    2011-05-01

    The present communication reports on the first preparation of reduced graphene oxide (rGO) via surface plasmon resonance (SPR)-induced visible light photocatalytic reduction of GO with the use of Ag nanoparticles (AgNPs) as a plasmonic photocatalyst in the presence of an electron donor (ED).

  17. Optogenetic inhibition of cortical afferents in the nucleus accumbens simultaneously prevents cue-induced transient synaptic potentiation and cocaine-seeking behavior

    PubMed Central

    Stefanik, Michael T.; Kupchik, Yonatan M.; Kalivas, Peter W.

    2017-01-01

    Animal models of relapse reveal that the motivation to seek drug is regulated by enduring morphological and physiological changes in the nucleus accumbens, as well as transient synaptic potentiation in the accumbens core (NAcore) that parallels drug-seeking behavior. The current study sought to examine the link between the behavioral and synaptic consequences of cue-induced cocaine seeking by optically silencing glutamatergic afferents to the NAcore from the prelimbic cortex (PL). Adeno-associated virus coding for the inhibitory opsin archaerhodopsin was microinjected into PL, and optical fibers were targeted to NAcore. Animals were trained to self-administer cocaine followed by extinction training, and then underwent cue-induced reinstatement in the presence or absence of 15 min of optically-induced inhibition of PL fibers in NAcore. Inhibiting the PL-to-NAcore projection blocked reinstated behavior and was paralleled by decreased dendritic spine head diameter and AMPA/NMDA ratio relative to sham-laser control rats. Interestingly, while spine density was elevated after extinction training, no further effects were observed by cued reinstatement or optical inhibition. These findings validate the critical role for PL afferents to the NAcore in simultaneously regulating both reinstated behavior and the associated transient synaptic potentiation. PMID:25663648

  18. Enhanced neuroprotective effects of resveratrol delivered by nanoparticles on hydrogen peroxide-induced oxidative stress in rat cortical cell culture.

    PubMed

    Lu, Xiaowei; Xu, Huae; Sun, Bo; Zhu, Zhenshu; Zheng, Donghui; Li, Xiaolin

    2013-05-06

    Resveratrol (RES) has recently been reported as a potential antioxidant in treatment of ischemia/reperfusion injury through attenuating oxidative stress and apoptosis. However, application of RES is limited for its insolubility and short half-time. Latest evidence raises the possibility of developing nanoparticle-based delivery systems with improved solubility, stability and cytotoxicity of lipophilic drug. Here, we reported first a simple way to produce RES-loaded nanoparticles (RES-NPs) based on poly(N-vinylpyrrolidone)-b-poly(ε-caprolactone) polymer and further evaluated the protective effect of RES-NPs on hydrogen peroxide-induced oxidative stress and apoptosis in rat cortical cell culture. The controlled release pattern of RES-loaded nanoparticles was characterized by in vitro release experiments. Cytotoxicity tests proved cytocompatibility of these nanoparticles with neurons. Shown by coumarin-6 loaded nanoparticles, the uptake of nanoparticles by neurons was considered through endocytosis, which could lead to higher uptake efficiency at lower concentration. Thereby, the hypothesis is raised that RES-NPs could demonstrate enhanced neuroprotection compared to an equivalent dose of free RES at lower concentration, especially. It was further supported by enhanced reduction of LDH release, elimination of ROS and MDA, and attenuation of apoptosis signal (ratio of Bax/Bcl-2, activation of caspase-3). RES-NPs could be a potential treatment needing intensive research for ischemia/reperfusion related disorder including stroke.

  19. Modification of the scattering of silver nanoparticles induced by Fabry-Pérot resonances rising from a finite Si layer

    NASA Astrophysics Data System (ADS)

    Marrocco, V.; Marani, R.; Grande, M.; Morea, G.; Calò, G.; Petruzzelli, V.; D'Orazio, A.

    2011-01-01

    In this paper we theoretically give evidence of the enhancement of scattering phenomena related to single metal nanoparticles having different shapes and located on a silicon layer having finite thickness, thus resembling a thin film solar cell. The study has been carried out in order to deeply understand how the presence of corners (nanobrick) or rounded edges (nanosphere) and the contact surfaces between the metal nanoparticle and the semiconductor affect the scattering when a finite Si layer is considered right below the nanoparticles. Arrays of such silver nanoparticles have also been investigated through a proprietary finite-difference time-domain-based code. The comparison with a typical configuration, where the semiconductor layer is semi-infinite, leads us to note that, in dependence on the shape and size of the nanoparticles, the finite layer, which acts as a Fabry-Pérot resonant cavity, is able to exceptionally twist the forward and backward scattering. In particular the forward scattering in all cases is enhanced, whereas the backward scattering seems to be more sensitive to the interference induced by resonances rising in the finite dielectric layers, since it exhibits opposite effects depending on the nanoparticle shapes.

  20. Possible involvement of NO/NOS signaling in hippocampal amyloid-beta production induced by transient focal cerebral ischemia in aged rats.

    PubMed

    Li, Song; Wang, Wei; Wang, Che; Tang, Yi-Yuan

    2010-02-12

    In the present study, to define the roles of nitric oxide (NO) signaling in amyloid-beta (A beta) production after transient cerebral ischemia, extracellular levels of NO and A beta were monitored by intracerebral microdialysis in the hippocampus of aged rats exposed to transient middle cerebral artery occlusion and reperfusion (MCAO/R). The results indicated that 1-h MCAO significantly upregulated hippocampal NO and A beta levels. In addition, the NO elevation preceded the A beta changes. The Western blotting suggested that acute hypoperfusion could increase the expression of beta-secretase 1 (BACE1) but not BACE2. The enhanced NO concentration in acute stage of MCAO/R was coincident with increased eNOS expression, while in subacute stage was coincident with increased iNOS and nNOS. Our results also indicated that pretreatment of L-NAME, one non-selective NOS inhibitor could decrease the BACE1 expression, reverse both NO and A beta changes and rescue the delayed neuronal death. These preliminary findings indicated that activation of NOS/NO signaling system could trigger A beta production through BACE1 pathway during acute ischemic episode. The present data may be important in understanding, at least in part, the pathological role of NO/NOS system involved in hippocampal A beta production and neuronal damage induced by transient cerebral ischemia.

  1. Electrochemical Impedance Spectroscopy (bio)sensing through hydrogen evolution reaction induced by gold nanoparticles.

    PubMed

    Mayorga-Martinez, Carmen C; Chamorro-Garcia, Alejandro; Merkoçi, Arben

    2015-05-15

    A new gold nanoparticle (AuNP) based detection strategy using Electrochemical Impedance Spectroscopy (EIS) through hydrogen evolution reaction (HER) is proposed. This EIS-HER method is used as an alternative to the conventional EIS based on [Fe(CN)6](3-/4-) or [Ru(NH3)6](3+/2+) indicators. The proposed method is based on the HER induced by AuNPs. EIS measurements for different amounts of AuNP are registered and the charge transfer resistance (Rct) was found to correlate and be useful for their quantification. Moreover the effect of AuNP size on electrical properties of AuNPs for HER using this sensitive technique has been investigated. Different EIS-HER signals generated in the presence of AuNPs of different sizes (2, 5, 10, 15, 20, and 50 nm) are observed, being the corresponding phenomena extendible to other nanoparticles and related catalytic reactions. This EIS-HER sensing technology is applied to a magneto-immunosandwich assay for the detection of a model protein (IgG) achieving improvements of the analytical performance in terms of a wide linear range (2-500 ng mL(-1)) with a good limit of detection (LOD) of 0.31 ng mL(-1) and high sensitivity. Moreover, with this methodology a reduction of one order of magnitude in the LOD for IgG detection, compared with a chroamperometric technique normally used was achieved.

  2. Nanoparticles formulation of Cuscuta chinensis prevents acetaminophen-induced hepatotoxicity in rats.

    PubMed

    Yen, Feng-Lin; Wu, Tzu-Hui; Lin, Liang-Tzung; Cham, Thau-Ming; Lin, Chun-Ching

    2008-05-01

    Cuscuta chinensis is a commonly used traditional Chinese medicine to nourish the liver and kidney. Due to the poor water solubility of its major constituents such as flavonoids and lignans, its absorption upon oral administration could be limited. The purpose of the present study was to use the nanosuspension method to prepare C. chinensis nanoparticles (CN), and to compare the hepatoprotective and antioxidant effects of C. chinensis ethanolic extract (CE) and CN on