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Find video protocols related to scientific articles indexed in Pubmed.
Silicon particles as trojan horses for potential cancer therapy.
J Nanobiotechnology
PUBLISHED: 07-24-2014
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BackgroundPorous silicon particles (PSiPs) have been used extensively as drug delivery systems, loaded with chemical species for disease treatment. It is well known from silicon producers that silicon is characterized by a low reduction potential, which in the case of PSiPs promotes explosive oxidation reactions with energy yields exceeding that of trinitrotoluene (TNT). The functionalization of the silica layer with sugars prevents its solubilization, while further functionalization with an appropriate antibody enables increased bioaccumulation inside selected cells.ResultsWe present here an immunotherapy approach for potential cancer treatment. Our platform comprises the use of engineered silicon particles conjugated with a selective antibody. The conceptual advantage of our system is that after reaction, the particles are degraded into soluble and excretable biocomponents.ConclusionsIn our study, we demonstrate in particular, specific targeting and destruction of cancer cells in vitro. The fact that the LD50 value of PSiPs-HER-2 for tumor cells was 15-fold lower than the LD50 value for control cells demonstrates very high in vitro specificity. This is the first important step on a long road towards the design and development of novel chemotherapeutic agents against cancer in general, and breast cancer in particular.
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Interaction of stable colloidal nanoparticles with cellular membranes.
Biotechnol. Adv.
PUBLISHED: 08-05-2013
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Due to their ultra-small size, inorganic nanoparticles (NPs) have distinct properties compared to the bulk form. The unique characteristics of NPs are broadly exploited in biomedical sciences in order to develop various methods of targeted drug delivery, novel biosensors and new therapeutic pathways. However, relatively little is known in the negotiation of NPs with complex biological environments. Cell membranes (CMs) in eukaryotes have dynamic structures, which is a key property for cellular responses to NPs. In this review, we discuss the current knowledge of various interactions between advanced types of NPs and CMs.
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[Physical exploration and morbidity of pelvic members in the diabetic patient type 2].
Rev Med Inst Mex Seguro Soc
PUBLISHED: 07-26-2013
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to determine the prevalence of the physical exploration and morbidity on pelvic members in the type 2 diabetic patient.
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Plasmonic Nanoprobes for Real-Time Optical Monitoring of Nitric Oxide inside Living Cells.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 07-22-2013
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An optical sensor was developed for the quantitative determination of intracellular nitric oxide. The sensor consists of plasmonic nanoprobes that have a coating of mesoporous silica and an inner gold island film functionalized with a chemoreceptor for NO.
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Multiple internalization pathways of polyelectrolyte multilayer capsules into mammalian cells.
ACS Nano
PUBLISHED: 07-16-2013
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Polyelectrolyte multilayer (PEM) capsules are carrier vehicles with great potential for biomedical applications. With the future aim of designing biocompatible, effective therapeutic delivery systems (e.g., for cancer), the pathway of internalization (uptake and fate) of PEM capsules was investigated. In particular the following experiments were performed: (i) the study of capsule co-localization with established endocytic markers, (ii) switching-off endocytotic pathways with pharmaceutical/chemical inhibitors, and (iii) characterization and quantification of capsule uptake with confocal and electron microscopy. As result, capsules co-localized with lipid rafts and with phagolysosomes, but not with other endocytic vesicles. Chemical interference of endocytosis with chemical blockers indicated that PEM capsules enter the investigated cell lines through a mechanism slightly sensitive to electrostatic interactions, independent of clathrin and caveolae, and strongly dependent on cholesterol-rich domains and organelle acidification. Microscopic characterization of cells during capsule uptake showed the formation of phagocytic cups (vesicles) to engulf the capsules, an increased number of mitochondria, and a final localization in the perinuclear cytoplasma. Combining all these indicators we conclude that PEM capsule internalization in general occurs as a combination of different sequential mechanisms. Initially, an adsorptive mechanism due to strong electrostatic interactions governs the stabilization of the capsules at the cell surface. Membrane ruffling and filopodia extensions are responsible for capsule engulfing through the formation of a phagocytic cup. Co-localization with lipid raft domains activates the cell to initiate a lipid-raft-mediated macropinocytosis. Internalization vesicles are very acidic and co-localize only with phagolysosome markers, excluding caveolin-mediated pathways and indicating that upon phagocytosis the capsules are sorted to heterophagolysosomes.
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CuTe nanocrystals: shape and size control, plasmonic properties, and use as SERS probes and photothermal agents.
J. Am. Chem. Soc.
PUBLISHED: 05-06-2013
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We report a procedure to prepare highly monodisperse copper telluride nanocubes, nanoplates, and nanorods. The procedure is based on the reaction of a copper salt with trioctylphosphine telluride in the presence of lithium bis(trimethylsilyl)amide and oleylamine. CuTe nanocrystals display a strong near-infrared optical absorption associated with localized surface plasmon resonances. We exploit this plasmon resonance for the design of surface-enhanced Raman scattering sensors for unconventional optical probes. Furthermore, we also report here our preliminary analysis of the use of CuTe nanocrystals as cytotoxic and photothermal agents.
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Polymer-coated nanoparticles interacting with proteins and cells: focusing on the sign of the net charge.
ACS Nano
PUBLISHED: 04-08-2013
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To study charge-dependent interactions of nanoparticles (NPs) with biological media and NP uptake by cells, colloidal gold nanoparticles were modified with amphiphilic polymers to obtain NPs with identical physical properties except for the sign of the charge (negative/positive). This strategy enabled us to solely assess the influence of charge on the interactions of the NPs with proteins and cells, without interference by other effects such as different size and colloidal stability. Our study shows that the number of adsorbed human serum albumin molecules per NP was not influenced by their surface charge. Positively charged NPs were incorporated by cells to a larger extent than negatively charged ones, both in serum-free and serum-containing media. Consequently, with and without protein corona (i.e., in serum-free medium) present, NP internalization depends on the sign of charge. The uptake rate of NPs by cells was higher for positively than for negatively charged NPs. Furthermore, cytotoxicity assays revealed a higher cytotoxicity for positively charged NPs, associated with their enhanced uptake.
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[Postoperative intra-abdominal foreign body resemblance to neoplasm. Report of a case and review of the bibliography].
Cir Cir
PUBLISHED: 03-26-2013
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Gossypibomas or textilomas are materials remain in the abdomen after surgery. It is very difficult to assess its impact due to medico-legal implications, hence the interest in the publication of this type of pathology.
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Job stress across gender: the importance of emotional and intellectual demands and social support in women.
Int J Environ Res Public Health
PUBLISHED: 01-05-2013
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This study aims to analyse whether any differences exist between the genders with respect to the effect of perceived Job Demands, Control and Support (JDCS model) on how individuals reach high levels of job stress. To do this, the perceived risk of suffering an illness or having an accident in the workplace is used as an outcome measure. The study is based on the First Survey on Working Conditions in Andalusia, which has a sample of 5,496 men and 2,779 women. We carry out a multi-sample analysis with structural equation models, controlling for age and sector. The results show that the generation of job stress has a different pattern in men and women. In the case of men, the results show that only one dimension of the job demands stressor is significant (quantitative demands), whose effect on job stress is weakened slightly by the direct effects of control and support. With women, in contrast, emotional and intellectual aspects (qualitative demands) are also statistically significant. Moreover, social support has a greater weakening effect on the levels of job stress in women than in men. These results suggest that applying the JDCS model in function of the gender will contribute to a greater understanding of how to reduce the levels of job stress in men and women, helping the design of more effective policies in this area.
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Specific detection of naturally occurring hepatitis C virus mutants with resistance to telaprevir and boceprevir (protease inhibitors) among treatment-naïve infected individuals.
J. Clin. Microbiol.
PUBLISHED: 11-23-2011
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The use of telaprevir and boceprevir, both protease inhibitors (PI), as part of the specifically targeted antiviral therapy for hepatitis C (STAT-C) has significantly improved sustained virologic response (SVR) rates. However, different clinical studies have also identified several mutations associated with viral resistance to both PIs. In the absence of selective pressure, drug-resistant hepatitis C virus (HCV) mutants are generally present at low frequency, making mutation detection challenging. Here, we describe a mismatch amplification mutation assay (MAMA) PCR method for the specific detection of naturally occurring drug-resistant HCV mutants. MAMA PCR successfully identified the corresponding HCV variants, while conventional methods such as direct sequencing, endpoint limiting dilution (EPLD), and bacterial cloning were not sensitive enough to detect circulating drug-resistant mutants in clinical specimens. Ultradeep pyrosequencing was used to confirm the presence of the corresponding HCV mutants. In treatment-naïve patients, the frequency of all resistant variants was below 1%. Deep amplicon sequencing allowed a detailed analysis of the structure of the viral population among these patients, showing that the evolution of the NS3 is limited to a rather small sequence space. Monitoring of HCV drug resistance before and during treatment is likely to provide important information for management of patients undergoing anti-HCV therapy.
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NIR-light triggered delivery of macromolecules into the cytosol.
J Control Release
PUBLISHED: 11-16-2011
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Light-responsive microcapsules constructed by layer-by-layer self-assembly are used as microcarriers to deliver different macromolecules inside cells. The microcapsules carry the macromolecules as cargo in their cavity, while their walls are modified with agglomerated gold nanoparticles. Microcapsules are incorporated by living cells and are then located in lysosomal compartments. Controlled release of the encapsulated material from the interior of the capsule to the cytosol is possible upon NIR-light irradiation. This is based on local heating of the gold nanoparticles upon NIR light and disruption of the capsule wall, what results on release of encapsulated materials. We illustrate several key advances in controlled release induced by light. First, we demonstrate that capsules can be opened individually, which allows for sequentially releasing cargo from different capsules within one single cell. Second, by using a pH-indicator as cargo the claim of release from the acidic lysosomal compartments to the neutral cytosol is experimentally evident which until now has been only speculated. Third, green fluorescent protein (GFP) is released to the cytosol while retaining its functionality. This demonstrates that proteins can be released without destruction by the local heating. Fourth, GFP is also administered in biodegradable capsules, which leads to a different release mechanism compared to externally triggering for light-responsive microcapsules.
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Light triggered detection of aminophenyl phosphate with a quantum dot based enzyme electrode.
J Nanobiotechnology
PUBLISHED: 08-18-2011
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An electrochemical sensor for p-aminophenyl phosphate (pAPP) is reported. It is based on the electrochemical conversion of 4-aminophenol (4AP) at a quantum dot (QD) modified electrode under illumination. Without illumination no electron transfer and thus no oxidation of 4AP can occur. pAPP as substrate is converted by the enzyme alkaline phosphatase (ALP) to generate 4AP as a product. The QDs are coupled via 1,4-benzenedithiol (BDT) linkage to the surface of a gold electrode and thus allow potential-controlled photocurrent generation. The photocurrent is modified by the enzyme reaction providing access to the substrate detection. In order to develop a photobioelectrochemical sensor the enzyme is immobilized on top of the photo-switchable layer of the QDs. Immobilization of ALP is required for the potential possibility of spatially resolved measurements. Geometries with immobilized ALP are compared versus having the ALP in solution. Data indicate that functional immobilization with layer-by-layer assembly is possible. Enzymatic activity of ALP and thus the photocurrent can be described by Michaelis- Menten kinetics. pAPP is detected as proof of principle investigation within the range of 25 ?M-1 mM.
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Molecular epidemiology of autochthonous dengue virus strains circulating in Mexico.
J. Clin. Microbiol.
PUBLISHED: 07-20-2011
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Dengue virus (DENV) is the most important arthropod-borne viral infection in humans. Here, the genetic relatedness among autochthonous DENV Mexican isolates was assessed. Phylogenetic and median-joining network analyses showed that viral strains recovered from different geographic locations are genetically related and relatively homogeneous, exhibiting limited nucleotide diversity.
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Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?
Virol. J.
PUBLISHED: 06-20-2011
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Varicella (chickenpox) exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV) infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV) radiation is the major environmental factor driving the molecular evolution of VZV.
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Polymer-coated nanoparticles: a universal tool for biolabelling experiments.
Small
PUBLISHED: 03-30-2011
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Water solubilization of nanoparticles is a fundamental prerequisite for many biological applications. To date, no single method has emerged as ideal, and several different approaches have been successfully utilized. These phase-transfer strategies are reviewed, indicating key advantages and disadvantages, and a discussion of conjugation strategies is presented. Coating of hydrophobic nanoparticles with amphiphilic polymers provides a generic pathway for the phase transfer of semiconductor, magnetic, metallic, and upconverting nanoparticles from nonpolar to polar environments. Amphiphilic polymers that include maleimide groups can be readily functionalized with chemical groups for specific applications. In the second, experimental part, some of the new chemical features of such polymer-capped nanoparticles are demonstrated. In particular, nanoparticles to which a pH sensitive fluorophore has been attached are described, and their use for intracellular pH-sensing demonstrated. It is shown that the properties of analyte-sensitive fluorophores can be tuned by using interactions with the underlying nanoparticles.
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How colloidal nanoparticles could facilitate multiplexed measurements of different analytes with analyte-sensitive organic fluorophores.
ACS Nano
PUBLISHED: 01-26-2011
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Multiplexed measurements of several analytes in parallel using analyte-sensitive organic fluorophores can be hampered by spectral overlap of the different fluorophores. The authors discuss how nanoparticles can help to overcome this problem. First, different organic fluorophores can be separated spatially by confining them to separate containers, each bearing a nanoparticle-based barcode. Second, by coupling different fluorophores to nanoparticles with different fluorescence lifetimes that serve as donors for excitation transfer, the effective fluorescence lifetime of the organic fluorophores as acceptors can be tuned by fluorescence resonance energy transfer (FRET). Thus, the fluorophores can be distinguished by their effective lifetimes. This is an example of how the modification of classical functional materials has already yielded improved and even new functionalities by the integration of nanoparticles with hybrid materials. We outline future opportunities in this area.
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Polymeric multilayer capsules delivering biotherapeutics.
Adv. Drug Deliv. Rev.
PUBLISHED: 01-13-2011
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Polymeric multilayer capsules have emerged as a novel drug delivery platform. These capsules are fabricated through layer-by-layer sequential deposition of polymers onto a sacrificial core template followed by the decomposition of this core yielding hollow capsules. The resulting nanometer thin membrane is permselective, allowing diffusion of water and ions but excluding larger molecules. Moreover, the sequential fabrication procedure allows a precise fine-tuning of the capsules physicochemical and biological properties. These properties have put polymeric multilayer capsules under major attention in the field of drug delivery. In this review we focus on polymeric multilayer capsule mediated delivery of biotechnological macromolecular drugs such as peptides, proteins and nucleic acids.
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[Advances and challenges for the prevention and control of AIDS in Mexico].
Gac Med Mex
PUBLISHED: 12-22-2010
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This document aims to give an epidemiological overview of HIV and AIDS in Mexico, to highlight some aspects of both the governmental and nongovernmental response, and to emphasize important challenges in the fight against the epidemic. The HIV and AIDS epidemic in Mexico is confined to specific groups such as men who have sex with men and intravenous drug users. It has low prevalence among general population, a percentage we aim to maintain. Universal access to retroviral treatment in Mexico is an achievement that is sustainable only if a constant reduction of new cases is accomplished. This can only be obtained by preventive measures that are based on evidence. It is necessary to strengthen nongovernmental associations that are working on prevention. In 2009, the number of nongovernmental associations that received official financing was relatively low. It is necessary to improve the epidemic vigilance and evaluation systems. This would allow better follow-up of the activities that confront the epidemic, and to obtain better feedback for the procedures.
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Correlating physico-chemical with toxicological properties of nanoparticles: the present and the future.
ACS Nano
PUBLISHED: 10-27-2010
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Nanotoxicology is still a new discipline. In this Perspective, both its origins and its future trends are discussed. In particular, we note several issues we consider important for publications in this field.
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Gene silencing mediated by magnetic lipospheres tagged with small interfering RNA.
Nano Lett.
PUBLISHED: 09-15-2010
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Lipospheres made from soy bean oil and a combination of the cationic lipid Metafectene and the helper lipid dioleoylphosphatidyl-ethanolamine were functionalized with magnetic nanoparticles (NPs) and small interfering RNA (siRNA). The resulting magnetic lipospheres loaded with siRNA are proven here as efficient nonviral vectors for gene silencing. Embedding magnetic NPs in the shell of lipospheres allows for magnetic force-assisted transfection (magnetofection) as well as magnetic targeting in both static and fluidic conditions mimicking the bloodstream.
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The effect of PEG-coated gold nanoparticles on the anti-proliferative potential of Specific Nutrient Synergy.
Nanotoxicology
PUBLISHED: 08-28-2010
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The role of PEG-coated gold nanoparticles (Au NPs) on the anti-proliferative effect of Specific Nutrient Synergy (SNS) on HTLV-1 infected (C91-PL and HuT-102) and non-infected (CEM and Jurkat) malignant T-lymphocytes cells, was investigated. When PEG-coated Au NPs (of different molecular weights) were added alone, there was no effect on either viability or proliferation of the leukemic cell lines studied. Treatment of cells with SNS and PEG (5 or 10 kDa) coated Au NP reduced significantly the proliferation in all cell lines tested; this reached more than 50% reduction as compared to the control for cells treated for 96 h. Data showed that the best anti-proliferative effect was obtained using SNS and Au NP coated with PEG of molecular weights of 5 and 10 kDa with almost no effect of PEG of lower molecular weights (0.75 and 2 kDa) or higher ones (20 kDa). This was true as well for HTLV-1 infected as for non-infected malignant T-lymphocytes. Electron microscopy results showed uptake of the gold particles to Jurkat cells. All described effects are specific to leukemia cell lines, and no effects were observed with freshly activated human mononuclear lymphocytes as control.
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De novo design of supercharged, unfolded protein polymers, and their assembly into supramolecular aggregates.
Macromol Rapid Commun
PUBLISHED: 08-06-2010
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Here we report for the first time the design and expression of highly charged, unfolded protein polymers based on elastin-like peptides (ELPs). Positively and negatively charged variants were achieved by introducing lysine and glutamic acid residues, respectively, within the repetitive pentapeptide units. Subsequently it was demonstrated that the monodisperse protein polyelectrolytes with precisely defined amino acid compositions, sequences, and stereochemistries can be transferred into superstructures exploiting their electrostatic interactions. Hollow capsules were assembled from oppositely charged protein chains by using the layer-by-layer technique. The structures of the capsules were analyzed by various microscopy techniques revealing the fabrication of multilayer containers. Due to their low toxicity in comparison to other polyelectrolytes, supercharged ELPs are appealing candidates for the construction of electrostatically induced scaffolds in biomedicine.
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[The AIDS epidemics in Mexico up to 2008].
Gac Med Mex
PUBLISHED: 04-29-2010
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The HIV/AIDS epidemics in Mexico has remained stable in terms of its slow growth during the last decade. Since the beginning of this century, efforts have been made to improve the epidemiological registration system. An important number of probability studies involving multiple geographic locations in Mexico and larger numbers of high-risk vulnerable populations have also been carried out, while continuing surveillance of volunteers for HIV testing. The analysis of recently obtained information and its comparison with that of the past century have unveiled the traces left by the new epidemics in its wake. The joint analysis of available information indicates that there are changes in transmission patterns of HIV/ AIDS that have modified the prevalence figures of previous decades. While transmission of blood-borne HIV infections have ceased, the number of HIV-seropositive drug users has increased, particularly in the northern of Mexico. In the population of men having sex with men (MSM) a decline in HIV prevalence has been noticed, excepting in the male sex working (MSW) group in whom a significant increase has been observed. The population with heterosexual practice clearly shows a steady growth of AIDS in women, particularly in young women from rural areas and in native women.
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Sphingosine 1-phosphate mediates chemotaxis of human primary fibroblasts via the S1P-receptor subtypes S1P? and S1P? and Smad-signalling.
Cytoskeleton (Hoboken)
PUBLISHED: 03-24-2010
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The sphingolipid sphingosine 1-phosphate (S1P) induces chemotaxis of primary fibroblasts. Thus, S1P exhibited a chemotactic effect in a concentration-dependent manner from 10?? to 10?? M; higher concentrations resulted in a loss of migration, and lower amounts were ineffective to evoke movement toward a concentration gradient of S1P. In congruence with the migratory response, S1P caused an extension of lamellipodia at the cell periphery of human fibroblasts and a rearrangement of the cytoskeleton. These effects were visible by phalloidin staining of actin filaments as well as focal adhesion turnover. As the molecular mechanism of S1P-mediated migration of fibroblasts has not been well characterized, we investigated whether S1P-receptors are involved in the chemotactic response. Indeed, inhibition of G(i) signalling markedly reduced motility towards S1P, suggesting an involvement of S1P-receptor subtypes. Moreover, downregulation of S1P? and S1P? indicated that these S1P-receptor subtypes are responsible for the chemotactic action of the bioactive sphingolipid. After having identified a crosstalk between Smad-proteins and S1P-signalling, we investigated whether Smad-activation is involved in the chemotactic response induced by S1P. Indeed S1P caused a Smad-activation via the S1P receptor subtypes S1P? and S1P?. Moreover, downregulation of Smad3 diminished the ability of S1P to mediate a chemotactic response in fibroblasts, indicating a crosstalk between TGF-?- and S1P-signalling.
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LbL multilayer capsules: recent progress and future outlook for their use in life sciences.
Nanoscale
PUBLISHED: 02-10-2010
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In this review we provide an overview of the recent progress in designing composite polymer capsules based on the Layer-by-Layer (LbL) technology demonstrated so far in material science, focusing on their potential applications in medicine, drug delivery and catalysis. The benefits and limits of current systems are discussed and the perspectives on emerging strategies for designing novel classes of therapeutic vehicles are highlighted.
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Nanopharmacy: Inorganic nanoscale devices as vectors and active compounds.
Pharmacol. Res.
PUBLISHED: 01-14-2010
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In this review we would like to aim at pharmaceuticals engineered on the nanoscale, i.e. pharmaceuticals where the nanomaterial plays the pivotal therapeutic role or adds additional functionality to the previous compound. Those cases would be considered as nanopharmaceuticals. The development of inorganic systems is opening the pharmaceutical nanotechnology novel horizons for diagnosis, imaging and therapy mainly because of their nanometer-size and their high surface area to volume ratios which allow for specific functions that are not possible in the micrometer-size particles. This review will focus on pharmaceutical forms that are based on inorganic nanoparticles where the nanosize of the inorganic component provides unique characteristics to the pharmaceutical form. Several examples of these systems that are either in pre-clinical investigation and under examination by the Food and Drug Administration (FDA) or that have been already approved by the FDA and are in clinical practice today like Gastromark, NanoTherm, Colloidal Gold for Lateral Flow tests, HfO-NPs, BioVant will be described and reviewed.
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One example on how colloidal nano- and microparticles could contribute to medicine.
Nanomedicine (Lond)
PUBLISHED: 12-05-2009
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Nanomedicine, nowadays, is a popular keyword in the media, although everyone seems to associate it with different visions, hopes and even fears. This article gives a perspective from two sides. From the point of view of a materials scientist, it will be pointed out what new materials will be possible, how they will be designed and which properties they could offer for diagnosis and treatment. From the point of view of a medical doctor, it will be pointed out which properties are actually desired and what materials are hoped for practical applications. The two different points of view indicate that, although sophisticated materials with advanced novel properties will be available in the future, they do not automatically match the requirements and demands of clinicians. The discussion is centerd around one example, multifunctional polyelectrolyte capsules, which might act as a nanosubmarine for in vivo sensing and delivery, which is used to highlight promising interfaces between both disciplines.
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Intracellular processing of proteins mediated by biodegradable polyelectrolyte capsules.
Nano Lett.
PUBLISHED: 10-29-2009
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Multilayer polyelectrolyte capsules made by layer-by-layer assembly of oppositely charged biodegradable polyelectrolytes were filled with a model of a nonactive prodrug, a self-quenched fluorescence-labeled protein. After capsule uptake by living cells, the walls of the capsules were actively degraded and digested by intracellular proteases. Upon capsule wall degradation, intracellular proteases could reach the protein cargo in the cavity of the capsules. Enzymatic fragmentation of the self-quenched fluorescence-labeled protein by proteases led to individual fluorescence-labeled peptides and thus revoked self-quenching of the dye. In this way nonactive (nonfluorescent) molecules were converted into active (fluorescent) molecules. The data demonstrates that biodegradable capsules are able to convert nonactive molecules (prodrugs) to active molecules (drugs) specifically only inside cells where appropriate enzymes are at hand. In this way only cargo inside the capsules reaching cells is activated, but not the cargo in capsules which remain extracellular. The peptide fragments undergo further processing inside the cells, leading ultimately to exocytosis.
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Evaluation of quantum dots applied as switchable layer in a light-controlled electrochemical sensor.
Anal Bioanal Chem
PUBLISHED: 10-09-2009
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Gold electrodes with switchable conductance are created by coating the gold surface with different colloidal quantum dots. For the quantum dot immobilization, a dithiol compound was used. By polarizing the electrode and applying a light pointer, local photocurrents were generated. The performance of this setup was characterized for a variety of different nanoparticle materials regarding drift and signal-to-noise ratio. We varied the following parameters: quantum dot materials and immobilization protocol. The results indicate that the performance of the sensor strongly depends on how the quantum dots are bound to the gold electrode. The best results were obtained by inclusion of an additional polyelectrolyte film, which had been fabricated using layer-by-layer assembly.
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Rapid hepatitis C virus divergence among chronically infected individuals.
J. Clin. Microbiol.
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Here, we analyze the viral divergence among hepatitis C virus (HCV) chronic cases infected with genotype 1. The intrahost viral evolution was assessed by deep sequencing using the 454 Genome Sequencer platform. The results showed a rapid nucleotide sequence divergence. This notorious short-term viral evolution is of the utmost importance for the study of HCV transmission, because direct links between related samples were virtually lost. Thus, rapid divergence of HCV significantly affects genetic relatedness studies and outbreak investigations.
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Protein-mediated synthesis, pH-induced reversible agglomeration, toxicity and cellular interaction of silver nanoparticles.
Colloids Surf B Biointerfaces
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Casein, a milk protein, is used to produce biotolerable and highly stable silver nanoparticles with a fair control over their size without using any additional reducing agent. These silver nanoparticles undergo reversible agglomeration to form protein-silver nanoparticle composite agglomerates as pH approaches to the isoelectric point of casein protein (pI=4.6). These agglomerates can then easily be re-dispersed in alkaline aqueous media with no obvious change in their optical properties. The nanoparticles can withstand high salt concentration (~0.5M), and can also be freeze-dried, stored as dry powder and then dispersed in aqueous media whenever required. More interestingly, by controlling the concentration of casein protein and pH, it was also possible to control the self-assembly of silver nanoparticles to produce fairly uniform spherical agglomerates. The nanoparticles and their agglomerates were thoroughly characterized using UV-visible and FTIR spectroscopy, TEM, SEM and DLS, etc. Cytotoxicity of the hybrid materials was examined using a Resazurin based cytotoxicity assay. After determining the LD(50) using NIH/3T3 fibroblast cells, the cellular interaction of these hybrid nanoparticles was studied to examine the behavior of casein-coated nanoparticles for their potential bio-applications.
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Methods for understanding the interaction between nanoparticles and cells.
Methods Mol. Biol.
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A critical view of the current toxicological methods used in nanotechnology and their related techniques. Hereby, toxicological effects derived from the intracellular accumulation and uptake will be examined. Then advantages/disadvantages of these methods will be discussed. Additional analytical techniques necessary to implement the results will be reviewed.
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The challenge to relate the physicochemical properties of colloidal nanoparticles to their cytotoxicity.
Acc. Chem. Res.
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Nanomaterials offer opportunities to construct novel compounds for many different fields. Applications include devices for energy, including solar cells, batteries, and fuel cells, and for health, including contrast agents and mediators for photodynamic therapy and hyperthermia. Despite these promising applications, any new class of materials also bears a potential risk for human health and the environment. The advantages and innovations of these materials must be thoroughly compared against risks to evaluate each new nanomaterial. Although nanomaterials are often used intentionally, they can also be released unintentionally either inside the human body, through wearing of a prosthesis or the inhalation of fumes, or into the environment, through mechanical wear or chemical powder waste. This possibility adds to the importance of understanding potential risks from these materials. Because of fundamental differences in nanomaterials, sound risk assessment currently requires that researchers perform toxicology studies on each new nanomaterial. However, if toxicity could be correlated to the basic physicochemical properties of nanomaterials, those relationships could allow researchers to predict potential risks and design nanomaterials with minimum toxicity. In this Account we describe the physicochemical properties of nanoparticles (NPs) and how they can be determined and discuss their general importance for cytotoxicity. For simplicity, we focus primarily on in vitro toxicology that examines the interaction of living cells with engineered colloidal NPs with an inorganic core. Serious risk assessment of NPs will require additional in vivo studies. Basic physicochemical properties of nanoparticulate materials include colloidal stability, purity, inertness, size, shape, charge, and their ability to adsorb environmental compounds such as proteins. Unfortunately, the correlation of these properties with toxicity is not straightforward. First, for NPs released either unintentionally or intentionally, it can be difficult to pinpoint these properties in the materials. Therefore, researchers typically use NP models with better defined properties, which dont include the full complexity of most industrially relevant materials. In addition, many of these properties are strongly mutually connected. Therefore, it can be difficult to vary individual properties in NP models while keeping the others constant.
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Quantification of the internalization patterns of superparamagnetic iron oxide nanoparticles with opposite charge.
J Nanobiotechnology
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Time-resolved quantitative colocalization analysis is a method based on confocal fluorescence microscopy allowing for a sophisticated characterization of nanomaterials with respect to their intracellular trafficking. This technique was applied to relate the internalization patterns of nanoparticles i.e. superparamagnetic iron oxide nanoparticles with distinct physicochemical characteristics with their uptake mechanism, rate and intracellular fate.The physicochemical characterization of the nanoparticles showed particles of approximately the same size and shape as well as similar magnetic properties, only differing in charge due to different surface coatings. Incubation of the cells with both nanoparticles resulted in strong differences in the internalization rate and in the intracellular localization depending on the charge. Quantitative and qualitative analysis of nanoparticles-organelle colocalization experiments revealed that positively charged particles were found to enter the cells faster using different endocytotic pathways than their negative counterparts. Nevertheless, both nanoparticles species were finally enriched inside lysosomal structures and their efficiency in agarose phantom relaxometry experiments was very similar.This quantitative analysis demonstrates that charge is a key factor influencing the nanoparticle-cell interactions, specially their intracellular accumulation. Despite differences in their physicochemical properties and intracellular distribution, the efficiencies of both nanoparticles as MRI agents were not significantly different.
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Antimicrobial hydantoin-containing polyesters.
Macromol Biosci
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A new N-hydantoin-containing biocompatible and enzymatically degradable polyester with antibacterial properties is presented. Different polyesters of dimethyl succinate, 1,4-butanediol, and 3-[N,N-di(?-hydroxyethyl)aminoethyl]-5,5-dimethylhydantoin in varying molar ratios are prepared via two-step melt polycondensation. The antibacterially active N-halamine form is obtained by subsequent chlorination of the polyesters with sodium hypochlorite. Chemical structures, thermal properties, and spherulitic morphologies of the copolymers are studied adopting FT-IR, NMR, TGA, DSC, WAXD, and POM. The polyesters exhibit antibacterial activity against Escherichia coli. The adopted synthetic approach can be transferred to other polyesters in a straightforward manner.
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Magnetic nanobeads decorated with silver nanoparticles as cytotoxic agents and photothermal probes.
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A versatile method for decorating magnetic nanobeads (being composite materials from polymers and superparamagnetic nanoparticles) with silver nanoparticles of 3-6 nm size is presented. Control over the silver nanoparticle coverage at the nanobead surface is achieved by changing the reaction parameters. Moreover, the silver-decorated magnetic nanobeads (Ag-MNBs) are studied with respect to their in vitro cytotoxicity on two distinct tumour cell lineages under different parameters, i.e., dose, incubation time, magnetic field applied during the culturing, silver ion leakage, and colloidal stability. It is found that enhanced magnetically mediated cellular uptake and silver ion leakage from the Ag-MNBs surface are the main factors which affect the toxicity of the Ag-MNBs and allow the half-maximal inhibitory dose of silver to be reduced to only 32 ?g mL(-1) . Furthermore, a synergic cytotoxicity induced by photo-activation of silver nanoparticles was also found.
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Subcellular carrier-based optical ion-selective nanosensors.
Front Pharmacol
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In this review, two carrier systems based on nanotechnology for real-time sensing of biologically relevant analytes (ions or other biological molecules) inside cells in a non-invasive way are discussed. One system is based on inorganic nanoparticles with an organic coating, whereas the second system is based on organic microcapsules. The sensor molecules presented within this work use an optical read-out. Due to the different physicochemical properties, both sensors show distinctive geometries that directly affect their internalization patterns. The nanoparticles carry the sensor molecule attached to their surfaces whereas the microcapsules encapsulate the sensor within their cavities. Their different size (nano and micro) enable each sensors to locate in different cellular regions. For example, the nanoparticles are mostly found in endolysosomal compartments but the microcapsules are rather found in phagolysosomal vesicles. Thus, allowing creating a tool of sensors that sense differently. Both sensor systems enable to measure ratiometrically however, only the microcapsules have the unique ability of multiplexing. At the end, an outlook on how more sophisticated sensors can be created by confining the nano-scaled sensors within the microcapsules will be given.
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pH-sensitive capsules as intracellular optical reporters for monitoring lysosomal pH changes upon stimulation.
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The concept of a long-term sensor for ion changes in the lysosome is presented. The sensor is made by layer-by-layer assembly of oppositely charged polyelectrolytes around ion-sensitive fluorophores, in this case for protons. The sensor is spontaneously incorporated by cells and resides over days in the lysosome. Intracellular changes of the concentration of protons upon cellular stimulation with pH-active agents are monitored by read-out of the sensor fluorescence at real time. With help of this sensor concept it is demonstrated that the different agents used (Monensin, Chloroquine, Bafilomycin A1, Amiloride) possessed different kinetics and mechanisms of action in affecting the intracellular pH values.
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Identification of hepatitis C virus transmission using a next-generation sequencing approach.
J. Clin. Microbiol.
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Here, we describe a transmission event of hepatitis C virus (HCV) among injection drug users. Next-generation sequencing (NGS) was used to assess the intrahost viral genetic variation. Deep amplicon sequencing of HCV hypervariable region 1 allowed for a detailed analysis of the structure of the viral population. Establishment of the genetic relatedness between cases was accomplished by phylogenetic analysis. NGS is a powerful tool with applications in molecular epidemiology studies and outbreak investigations.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.