Este trabajo fue apoyado en parte por el Fondo Ishaya Horowitz.

IL-8 del ensayo: <ol><li> La mezcla de reacción fueron las siguientes cuatro componentes en 100 l de volumen final de tampón de ensayo en sus respectivas concentraciones. 10 l de bolas magnéticas con anticuerpos de captura en 100 bolas / l final de las concentraciones, 2 l de biotina IL-8 de anticuerpos en una concentración final nano-gram/μl, 1 l de proteínas fluorescentes de 20 estreptavidina concentración final nano-gram/μl, y 1 l de IL-8 blanco a 0,48 pico-gram/μl. Los componentes se añaden uno por uno para el tampón de ensayo y luego se agita durante 30 minutos. </li><li> Una reacción de control se prepara de la misma manera sin la IL-8 blanco. </li><li> Las reacciones son más tarde puesto sin ningún tipo de separación o etapa de lavado en las cubetas e inspeccionados con el sistema de MMB. </li></ol> MMB sistema: <ol><li> Coloque la cubeta en su posición entre los dos polos electromagnéticos. </li><li> Operar la corriente de modulación y esperar 30 segundos para permitir la agregación y la condensación de las cuentas </li><li> Medir la señal del amplificador lock-in con un osciloscopio. </li></ol> Los resultados representativos: La inspección visual de las cuentas agregadas presenta una clara diferencia entre la reacción con el objetivo y la reacción, sin el objetivo. En todas las reacciones con el objetivo, el exceso acumulado un agregado único y denso que se movía dentro y fuera del haz de láser de una manera unirse. Sin embargo, en toda la reacción sin que el objetivo, las cuentas fueron menos agregados y su movimiento se unen menos (ver Figura 1). <img src="/files/ftp_upload/1935/1935fig1.jpg" alt="Figura 1" /> Figura 1: la inspección visual de inmunoensayo sándwich &quot;(a) sin el objetivo de IL-8 (b) Con el objetivo de IL-8. El reloj de modulación polo (amarillo) y la señal de salida PMT (magenta), mientras que la detección de pico 0,48 gramos de IL-8 blanco se presenta en la Figura 1 (a). La modulación de frecuencia para cada polo está a 2 Hz. Sin embargo, como era de esperar teóricamente, cuando las perlas pasar el rayo láser, el PMT detecta la luz fluorescente y hay un pico en la tensión de salida PMT. Por lo tanto, la frecuencia de demodulación es de 4 Hz. Cuando la señal de la tensión premenstrual y el reloj se duplicó de modulación (4 Hz) se introducen en la cerradura en el amplificador, el detector de fases detecta la sincronización y los resultados con alto voltaje (ver Figura 2). <img src="/files/ftp_upload/1935/1935fig2.jpg" alt="Figura 2" /> Figura 2: (a) el reloj de modulación (amarillo) y la señal de PMT (magenta) cuando la detección de pico 0,48 gramos de IL-8 blanco. (B) El bloqueo del resultado de la tensión del amplificador en dos análisis diferentes. El bloqueo del amplificador no detectó ninguna señal de que la muestra de control se puso a prueba. Este hecho, junto con la diferencia visual en la agregación sugiere que el sistema MMB puede identificar claramente la presencia de IL-8 blanco.

<ol>
	<li>Danielli, A., Arie, A., Porat, N., Ehrlich, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+fluorescent-labeled+probes+at+sub-picomolar+concentrations+by+magnetic+modulation.">Detection of fluorescent-labeled probes at sub-picomolar concentrations by magnetic modulation.</a> Optics Express. 16, 19253-19259 (2008).</li><li>Danielli, A., Porat, N., Arie, A., Ehrlich, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+homogenous+detection+of+the+Ibaraki+virus+NS3+cDNA+at+pico-molar+concentrations+by+magnetic+modulation.">Rapid homogenous detection of the Ibaraki virus NS3 cDNA at pico-molar concentrations by magnetic modulation.</a> Biosensors and Bioelectronics. 25, 858-863 (2009).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Bio-Rad "Human angiogenesis assay panel". , .</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Instruction+Manual.">Instruction Manual.</a> Bio-Plex Precision Pro Cytokine Assay. , .</li></ol>

En resumen, hemos demostrado que el sistema de MMB se puede utilizar para detectar la presencia de IL-8 blanco a bajas concentraciones (0,5 pico gramos es el límite de detección de los ensayos de precisión Bio-Plex citoquinas Pro [3,4]). La capacidad del sistema no se limita a la IL-8 y se puede utilizar para detectar otras proteínas. Las ventajas del sistema de MMB son la capacidad de detectar el objetivo rápidamente y sin ningún tipo de separación o paso de lavado. Por lo tanto, facilita el proceso de detecció...

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<td>Bio-Plex Pro Human Cytokine IL-8 set</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>171-B5008M</td>
<td>&nbsp;</td>
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<td>Recombinant human IL-8 target</td>
<td>&nbsp;</td>
<td>Thermo Scientific</td>
<td>R202625</td>
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<tr>
<td>Biotinylated monoclonal mouse anti human IL-8 antibody G265-8</td>
<td>&nbsp;</td>
<td>BD Biosciences</td>
<td>554718</td>
<td>&nbsp;</td>
<tr>
<td>Streptavidin coupled fluorescent protein</td>
<td>&nbsp;</td>
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rapid homogeneous detection of biological assays using magnetic modulation biosensing system

Una modulación magnética sistema de biosensores (MMB) [1,2] con rapidez y de manera homogénea detectado dianas biológicas a bajas concentraciones, sin ningún tipo de lavado o etapa de separación. Cuando la IL-8 fue objetivo, un «sandwich&#39; ensayo basado adjunta bolas magnéticas con IL-8 anticuerpo de captura a la estreptavidina acoplados a la proteína fluorescente a través de la IL-8 blanco y un IL-8 con biotina de anticuerpos. El perlas magnéticas se maniobran en el movimiento oscilatorio de la aplicación de un gradiente de campo magnético a través alternando dos polos electromagnéticos. Las proteínas fluorescentes, que se adjuntan a las perlas magnéticas se condensan en el área de detección y sus movimientos dentro y fuera de un rayo láser ortogonales produce una señal periódica fluorescente que se demodulada con detección síncrona. El sistema de modulación biosensores magnéticos se utilizó anteriormente para detectar las secuencias de codificación de la proteína no estructural del virus Ibaraki 3 (NS3) del ADN complementario (ADNc) [2]. Las técnicas que se muestran en este trabajo para la manipulación externa y la condensación de las partículas se pueden utilizar para otras aplicaciones, por ejemplo, entrega de medicamentos magnéticamente acoplados<em&gt; En-vivo</em&gt; O mejorar el contraste de<em&gt; En-vivo</em&gt; Aplicaciones de imagen.

Watch this Scientific Journal Video about Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System at JoVE.com

Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System

Magnética modulación del sistema de biosensores se utiliza a la rápida, sensible y simplemente detectar ensayos biológicos, como las moléculas de ADN y las proteínas.

Detección rápida homogénea de Ensayos Biológicos Usando el Sistema de modulación magnética biosensores

A magnetic modulation biosensing system (MMB) [1,2] rapidly and homogeneously detected biological targets at low concentrations without any washing or ...

rapid-homogeneous-detection-biological-assays-using-magnetic

Research

JoVE Journal

Biology

9.5K vistas.  Tel Aviv University. Magnética modulación del sistema de biosensores se utiliza a la rápida, sensible y simplemente detectar ensayos biológicos, como las moléculas de ADN y las proteínas.

Video: Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System

ELIME (Enzyme Linked Immuno Magnetic Electrochemical) Method for Mycotoxin Detection

Immunoassays are a valid alternative to the more expensive and time consuming quantitative HPLC or GC1, 2 methods for the screening detection of hazardous mycotoxins in food commodities. In this protocol we show how to fabricate and interrogate an electrochemical competitive Enzyme linked immunomagnetic assay based on the use of magnetic beads as solid support for the immunochemical chain3 and screen printed electrodes as sensing platform.
Our method aims to determine the total amount of HT-2 and T-2 toxins, mycotoxins belonging to the trichothecenes family and of great concern for human health4. The use of an antibody clone with a cross reactivity of 100% towards HT-2 and T-2 allows to simultaneously detect both toxins with similar sensitivity5.
The first step of our assay is the coating step where we immobilize HT2-KLH conjugate toxin on the surface of magnetic beads. After a blocking step, necessary to avoid non-specific absorptions, the addition of a monoclonal antibody allows the competition between immobilized HT-2 and free HT-2 or T-2 present in the sample or dissolved in a standard solution.
At the end of the competition step, the amount of monoclonal antibody linked to the immobilized HT-2 will be inversely proportional to the amount of toxin in the sample solution.
A secondary antibody labeled with alkaline phosphatase (AP) is used to reveal the binding between the specific antibody and the immobilized HT-2. The final measurement step is performed by dropping an aliquot of magnetic bead suspension, corresponding to a specific sample/standard solution, on the surface of a screen-printed working electrode; magnetic beads are immobilized and concentrated by means of a magnet placed precisely under the screen-printed electrode. After two minutes of incubation between magnetic beads and a substrate for AP, the enzymatic product is detected by Differential Pulse Voltammetry (DPV) using a portable instrument (PalmSens) also able to initiate automatically eight measurements within an interval of few seconds.

ELIME Enzyme Linked Immuno Magnetic Electrochemical Method for Mycotoxin Detection

A protocol to detect trichothecenes (mycotoxins of concern for human health) using a newly developed screening method based on a competitive immunochemical method and a final electrochemical detection is demonstrated.

ELIME (Enzyme Linked Inmuno magnética químicos) Método para la detección de micotoxinas

Immunoassays are a valid alternative to the more expensive and time consuming quantitative HPLC or GC1, 2 methods for the screening detection of hazardous ...

Investigación

Biología

Analysis of Schwann-astrocyte Interactions Using In Vitro Assays

Schwann cells are one of the commonly used cells in repair strategies following spinal cord injuries. Schwann cells are capable of supporting axonal regeneration and sprouting by secreting growth factors 1,2 and providing growth promoting adhesion molecules 3 and extracellular matrix molecules 4. In addition they myelinate the demyelinated axons at the site of injury 5.
However following transplantation, Schwann cells do not migrate from the site of implant and do not intermingle with the host astrocytes 6,7. This results in formation of a sharp boundary between the Schwann cells and astrocytes, creating an obstacle for growing axons trying to exit the graft back into the host tissue proximally and distally. Astrocytes in contact with Schwann cells also undergo hypertrophy and up-regulate the inhibitory molecules 8-13.
In vitro assays have been used to model Schwann cell-astrocyte interactions and have been important in understanding the mechanism underlying the cellular behaviour.
These in vitro assays include boundary assay, where a co-culture is made using two different cells with each cell type occupying different territories with only a small gap separating the two cell fronts. As the cells divide and migrate, the two cellular fronts get closer to each other and finally collide. This allows the behaviour of the two cellular populations to be analyzed at the boundary. Another variation of the same technique is to mix the two cellular populations in culture and over time the two cell types segregate with Schwann cells clumped together as islands in between astrocytes together creating multiple Schwann-astrocyte boundaries.
The second assay used in studying the interaction of two cell types is the migration assay where cellular movement can be tracked on the surface of the other cell type monolayer 14,15. This assay is commonly known as inverted coverslip assay. Schwann cells are cultured on small glass fragments and they are inverted face down onto the surface of astrocyte monolayers and migration is assessed from the edge of coverslip.
Both assays have been instrumental in studying the underlying mechanisms involved in the cellular exclusion and boundary formation. Some of the molecules identified using these techniques include N-Cadherins 15, Chondroitin Sulphate proteoglycans(CSPGs) 16,17, FGF/Heparin 18, Eph/Ephrins19.
This article intends to describe boundary assay and migration assay in stepwise fashion and elucidate the possible technical problems that might occur.

Analysis of Schwann-astrocyte Interactions Using In Vitro Assays

This article intends to describe in stepwise fashion the commonly used in vitro assays used in studying Schwann cell-asrtocyte interactions.

El análisis de Schwann-astrocito interacciones utilizando In Vitro Ensayos

Schwann cells are one of the commonly used cells in repair strategies following spinal cord injuries. Schwann cells are capable of supporting axonal ...

Rapid PCR Thermocycling using Microscale Thermal Convection

Many molecular biology assays depend in some way on the polymerase chain reaction (PCR) to amplify an initially dilute target DNA sample to a detectable concentration level. But the design of conventional PCR thermocycling hardware, predominantly based on massive metal heating blocks whose temperature is regulated by thermoelectric heaters, severely limits the achievable reaction speed1. Considerable electrical power is also required to repeatedly heat and cool the reagent mixture, limiting the ability to deploy these instruments in a portable format.
Thermal convection has emerged as a promising alternative thermocycling approach that has the potential to overcome these limitations2-9. Convective flows are an everyday occurrence in a diverse array of settings ranging from the Earth's atmosphere, oceans, and interior, to decorative and colorful lava lamps. Fluid motion is initiated in the same way in each case: a buoyancy driven instability arises when a confined volume of fluid is subjected to a spatial temperature gradient. These same phenomena offer an attractive way to perform PCR thermocycling. By applying a static temperature gradient across an appropriately designed reactor geometry, a continuous circulatory flow can be established that will repeatedly transport PCR reagents through temperature zones associated with the denaturing, annealing, and extension stages of the reaction (Figure 1). Thermocycling can therefore be actuated in a pseudo-isothermal manner by simply holding two opposing surfaces at fixed temperatures, completely eliminating the need to repeatedly heat and cool the instrument.
One of the main challenges facing design of convective thermocyclers is the need to precisely control the spatial velocity and temperature distributions within the reactor to ensure that the reagents sequentially occupy the correct temperature zones for a sufficient period of time10,11. Here we describe results of our efforts to probe the full 3-D velocity and temperature distributions in microscale convective thermocyclers12. Unexpectedly, we have discovered a subset of complex flow trajectories that are highly favorable for PCR due to a synergistic combination of (1) continuous exchange among flow paths that provides an enhanced opportunity for reagents to sample the full range of optimal temperature profiles, and (2) increased time spent within the extension temperature zone the rate limiting step of PCR. Extremely rapid DNA amplification times (under 10 min) are achievable in reactors designed to generate these flows.

We describe a novel method to perform DNA replication via the polymerase chain reaction (PCR). Thermal convection is harnessed to continuously shuttle reagents between denaturing, annealing, and extension conditions by maintaining opposing surfaces of the reactor at constant temperature. This inherently simple design promises to make rapid PCR more accessible.

PCR rápido ciclo térmico con convección térmica microescala

Many molecular biology assays depend in some way on the polymerase chain reaction (PCR) to amplify an initially dilute target DNA sample to a detectable ...

High-throughput Screening and Biosensing with Fluorescent C. elegans Strains

High-throughput screening (HTS) is a powerful approach for identifying chemical modulators of biological processes. However, many compounds identified in screens using cell culture models are often found to be toxic or pharmacologically inactive in vivo1-2. Screening in whole animal models can help avoid these pitfalls and streamline the path to drug development.
C. elegans is a multicellular model organism well suited for HTS. It is small (&lt;1 mm) and can be economically cultured and dispensed in liquids. C. elegans is also one of the most experimentally tractable animal models permitting rapid and detailed identification of drug mode-of-action3.
We describe a protocol for culturing and dispensing fluorescent strains of C. elegans for high-throughput screening of chemical libraries or detection of environmental contaminants that alter the expression of a specific gene. Large numbers of developmentally synchronized worms are grown in liquid culture, harvested, washed, and suspended at a defined density. Worms are then added to black, flat-bottomed 384-well plates using a peristaltic liquid dispenser. Small molecules from a chemical library or test samples (e.g., water, food, or soil) can be added to wells with worms. In vivo, real-time fluorescence intensity is measured with a fluorescence microplate reader. This method can be adapted to any inducible gene in C. elegans for which a suitable reporter is available. Many inducible stress and developmental transcriptional pathways are well defined in C. elegans and GFP transgenic reporter strains already exist for many of them4. When combined with the appropriate transgenic reporters, our method can be used to screen for pathway modulators or to develop robust biosensor assays for environmental contaminants. 
We demonstrate our C. elegans culture and dispensing protocol with an HTS assay we developed to monitor the C. elegans cap &#x2018;n&#x2019; collar transcription factor SKN-1. SKN-1 and its mammalian homologue Nrf2 activate cytoprotective genes during oxidative and xenobiotic stress5-10. Nrf2 protects mammals from numerous age-related disorders such as cancer, neurodegeneration, and chronic inflammation and has become a major chemotherapeutic target11-13.Our assay is based on a GFP transgenic reporter for the SKN-1 target gene gst-414, which encodes a glutathione-s transferase6. The gst-4 reporter is also a biosensor for xenobiotic and oxidative chemicals that activate SKN-1 and can be used to detect low levels of contaminants such as acrylamide and methyl-mercury15-16.

High-throughput Screening and Biosensing with Fluorescent C. elegans Strains

A procedure for liquid-based culturing and dispensing of C. elegans strains expressing fluorescent reporter proteins is described that does not require expensive sorting equipment. This approach can be applied to numerous inducible C. elegans genes for drug discovery or biosensing of contaminants.

Selección de alto rendimiento y biosensores fluorescentes con C. elegans Las cepas

High-throughput screening (HTS) is a powerful approach for identifying chemical modulators of biological processes.  However, many compounds identified in ...

Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation (BiFC) System

We have developed a BiFC technique to test the interaction between two proteins in vivo. This is accomplished by splitting a yellow fluorescent protein (YFP) into two non-overlapping fragments. Each fragment is cloned in-frame to a gene of interest. These constructs can then be co-transformed into Nicotiana benthamiana via Agrobacterium mediated transformation, allowing the transit expression of fusion proteins. The reconstitution of YFP signal only occurs when the inquest proteins interact 1-7. To test and validate the protein-protein interactions, BiFC can be used together with yeast two hybrid (Y2H) assay. This may detect indirect interactions which can be overlooked in the Y2H. Gateway technology is a universal platform that enables researchers to shuttle the gene of interest (GOI) into as many expression and functional analysis systems as possible8,9. Both the orientation and reading frame can be maintained without using restriction enzymes or ligation to make expression-ready clones. As a result, one can eliminate all the re-sequencing steps to ensure consistent results throughout the experiments. We have created a series of Gateway compatible BiFC and Y2H vectors which provide researchers with easy-to-use tools to perform both BiFC and Y2H assays10. Here, we demonstrate the ease of using our BiFC system to test protein-protein interactions in N. benthamiana plants.

Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation BiFC System

We have developed a technique to test protein-protein interactions in plant. A yellow fluorescent protein (YFP) is split into two non-overlapping fragments. Each fragment is cloned in-frame to a gene of interest via Gateway system, enabling expression of fusion proteins. Reconstitution of YFP signal only occurs when the inquest proteins interact.

Detección de interacciones de proteínas en la planta mediante un Gateway Compatible Complementación fluorescencia bimoleculares (BiFC) del sistema

We have developed a BiFC technique to test the interaction between two proteins in vivo. This is accomplished by splitting a yellow fluorescent protein ...

Rapid Protocol for Preparation of Electrocompetent Escherichia coli and Vibrio cholerae

Electroporation has become a widely used method for rapidly and efficiently introducing foreign DNA into a wide range of cells. Electrotransformation has become the method of choice for introducing DNA into prokaryotes that are not naturally competent. Electroporation is a rapid, efficient, and streamlined transformation method that, in addition to purified DNA and competent bacteria, requires commercially available gene pulse controller and cuvettes. In contrast to the pulsing step, preparation of electrocompetent cells is time consuming and labor intensive involving repeated rounds of centrifugation and washes in decreasing volumes of sterile, cold water, or non-ionic buffers of large volumes of cultures grown to mid-logarithmic phase of growth. Time and effort can be saved by purchasing electrocompetent cells from commercial sources, but the selection is limited to commonly employed E. coli laboratory strains. We are hereby disseminating a rapid and efficient method for preparing electrocompetent E. coli, which has been in use by bacteriology laboratories for some time, can be adapted to V. cholerae and other prokaryotes. While we cannot ascertain whom to credit for developing the original technique, we are hereby making it available to the scientific community.

Rapid Protocol for Preparation of Electrocompetent Escherichia coli and Vibrio cholerae

Electroporation is a commonly employed method for introducing DNA into bacteria in a process known as transformation. Traditional protocols for the preparation of electrocompetent cells are time consuming and labor intensive. This article describes an alternate, rapid, and efficient method for the preparation of electrocompetent cells presently employed by some laboratories.

Protocolo rápido para la preparación de electrocompetentes<em&gt; Escherichia coli</em&gt; Y<em&gt; Vibrio cholerae</em

Electroporation has become a widely used method for rapidly and efficiently introducing foreign DNA into a wide range of cells. Electrotransformation has ...

Rapid and Efficient Zebrafish Genotyping Using PCR with High-resolution Melt Analysis

Zebrafish is a powerful vertebrate model system for studying development, modeling disease, and performing drug screening. Recently a variety of genetic tools have been introduced, including multiple strategies for inducing mutations and generating transgenic lines. However, large-scale screening is limited by traditional genotyping methods, which are time-consuming and labor-intensive. Here we describe a technique to analyze zebrafish genotypes by PCR combined with high-resolution melting analysis (HRMA).&#160;This approach is rapid, sensitive, and inexpensive, with lower risk of contamination artifacts.&#160;Genotyping by PCR with HRMA can be used for embryos or adult fish, including in high-throughput screening protocols.

PCR combined with high-resolution melt analysis (HRMA) is demonstrated as a rapid and efficient method to genotype zebrafish.

Rápido y Eficiente de pez cebra Genotipado Utilizando PCR con análisis del derretimiento de alta resolución

Zebrafish is a powerful vertebrate model system for studying development, modeling disease, and performing drug screening. Recently a variety of genetic ...

Simple Bulk Readout of Digital Nucleic Acid Quantification Assays

Digital assays are powerful methods that enable detection of rare cells and counting of individual nucleic acid molecules. However, digital assays are still not routinely applied, due to the cost and specific equipment associated with commercially available methods. Here we present a simplified method for readout of digital droplet assays using a conventional real-time PCR instrument to measure bulk fluorescence of droplet-based digital assays.
We characterize the performance of the bulk readout assay using synthetic droplet mixtures and a droplet digital multiple displacement amplification (MDA) assay. Quantitative MDA particularly benefits from a digital reaction format, but our new method&#160;applies to any digital assay. For established digital assay protocols such as digital PCR, this method serves to speed up and simplify assay readout.
Our bulk readout methodology brings the advantages of partitioned assays without the need for specialized readout instrumentation. The principal limitations of the bulk readout methodology are reduced dynamic range compared with droplet-counting platforms and the need for a standard sample, although the requirements for this standard are less demanding than for a conventional real-time experiment. Quantitative whole genome amplification (WGA) is used to test for contaminants in WGA reactions and is the most sensitive way to detect the presence of DNA fragments with unknown sequences, giving the method great promise in diverse application areas including pharmaceutical quality control and astrobiology.

We describe an endpoint digital assay for quantifying nucleic acids with a simplified (analog) readout. We measure bulk fluorescence of droplet-based digital assays using a standard qPCR machine rather than specialized instrumentation and confirm our results by microscopy.

Lectura granel simple de Digital ácidos nucleicos Cuantificación ensayos

Digital assays are powerful methods that enable detection of rare cells and counting of individual nucleic acid molecules. However, digital assays are ...

High Content Screening Analysis to Evaluate the Toxicological Effects of Harmful and Potentially Harmful Constituents (HPHC)

Cigarette smoke (CS) is a major risk factor for cardiovascular and lung diseases. Because CS is a complex aerosol containing more than 7,000 chemicals1 it is challenging to assess the contributions of individual constituents to its overall toxicity. Toxicological profiles of individual constituents as well as mixtures can be however established in vitro, by applying high through-put screening tools, which enable the profiling of Harmful and Potentially Harmful Constituents (HPHCs) of tobacco smoke, as defined by the U.S. Food and Drug Administration (FDA).2
For an initial assessment, an impedance-based instrument was used for a real-time, label-free assessment of the compound&#39;s toxicity. The instrument readout relies on cell adhesion, viability and morphology that all together provide an overview of the cell status. A dimensionless parameter, named cell index, is used for quantification. A set of different staining protocols was developed for a fluorescence imaging-based investigation and a HCS platform was used to gain more in-depth information on the kind of cytotoxicity elicited by each HPHC.
Of the 15 constituents tested, only five were selected for HCS-based analysis as they registered a computable LD50 (&#60; 20 mM). These included 1-aminonaphtalene, Arsenic (V), Chromium (VI), Crotonaldehyde and Phenol. Based on their effect in the HCS, 1-aminonaphtalene and Phenol could be identified to induce mitochondrial dysfunction, and, together with Chromium (VI) as genotoxic based on the increased histone H2AX phosphorylation. Crotonaldehyde was identified as an oxidative stress inducer and Arsenic as a stress kinase pathway activator.
This study demonstrates that a combination of impedance-based and HCS technologies provides a robust tool for in vitro assessment of CS constituents.

High Content Screening Analysis to Evaluate the Toxicological Effects of Harmful and Potentially Harmful Constituents HPHC

The objective of the study was to assess the biological impact of 15 cigarette smoke constituents using a combination of an impedance-based real time cell analyzer and a high-content screening (HCS)-based platform for toxicological assessment in vitro. This study provides information on effective doses, toxicity and modes of action of the tested compounds.

Análisis alta Content Screening para evaluar los efectos toxicológicos de nocivo Componentes y potencialmente perjudicial (HPHC)

Cigarette smoke (CS) is a major risk factor for cardiovascular and lung diseases. Because CS is a complex aerosol containing more than 7,000 chemicals1 it ...

Rapid Freezing using Sandwich Freezing Device for Good Ultrastructural Preservation of Biological Specimens in Electron Microscopy

Chemical fixation has been used for observing the ultrastructure of cells and tissues. However, this method does not adequately preserve the ultrastructure of cells; artifacts and extraction of cell contents are usually observed. Rapid freezing is a better alternative for the preservation of cell structure. Sandwich freezing of living yeast or bacteria followed by freeze-substitution has been used for observing the exquisite natural ultrastructure of cells. Recently, sandwich freezing of glutaraldehyde-fixed cultured cells or human tissues has also been used to reveal the ultrastructure of cells and tissues. 
These studies have thus far been carried out with a handmade sandwich freezing device, and applications to studies in other laboratories have been limited. A new sandwich freezing device has recently been fabricated and is now commercially available. The present paper shows how to use the sandwich freezing device for rapid freezing of biological specimens, including bacteria, yeast, cultured cells, isolated cells, animal and human tissues, and viruses. Also shown is the preparation of specimens for ultrathin sectioning after rapid freezing and procedures for freeze-substitution, resin embedding, trimming of blocks, cutting of ultrathin sections, recovering of sections, staining, and covering of grids with support films.

Here we show how to use the sandwich freezing device for rapid freezing of biological specimens, including bacteria, yeast, cultured cells, isolated cells, animal and human tissues, and viruses. We also show how to prepare specimens for ultrathin sectioning after rapid freezing.

Congelación rápida utilizando un dispositivo de congelación sándwich para una buena preservación ultraestructural de especímenes biológicos en microscopía electrónica