Los aneurismas cerebrales son ensanchamiento o abombamiento anormal de un segmento localizada de un vaso sanguíneo intracraneal. Estas lesiones generalmente ocurren en las ramificaciones de la nave matriz, como resultado de un debilitamiento progresivo de la pared arterial. Los aneurismas cerebrales son más comunes detectados después de que el aneurisma se rompe causando una hemorragia subaracnoidea. Esta forma de hemorragia intracraneal conlleva un riesgo del 45% de la mortalidad durante el primer mes después de la ruptura y los sobrevivientes con frecuencia experimentan graves lesiones neurológicas permanentes 1. Recientemente, debido a la mayor utilización de las técnicas de imagen avanzadas, como la resonancia magnética y tomografía computarizada, los aneurismas cerebrales son frecuentemente identificados antes de la ruptura y las opciones para el tratamiento de los aneurismas cerebrales incluyen recorte quirúrgico y embolización con espirales. En este informe de video, se describe el recorte de microcirugía de un aneurisma de la arteria cerebral media utilizando una sonda de ultrasonidos para la evaluación perivascular de flujo de los vasos sanguíneos. El objetivo de recorte de cirugía de un aneurisma cerebral es eliminar definitivamente el aneurisma de la circulación, preservando el flujo sanguíneo a través de los padres y las arterias distales. Por lo general, el microscopio quirúrgico se utiliza para proporcionar una mejor visualización del aneurisma y permitir la disección exitosa del aneurisma y la colocación de un clip de titanio en su base. La colocación de clip de incorrecta puede provocar un aneurisma residual o la oclusión parcial o total de las arterias distales, que puede causar un infarto cerebral. Varios estudios con angiografía intraoperatoria durante la cirugía de aneurisma han demostrado la insuficiencia de la inspección visual directa en la predicción del mantenimiento de un flujo sanguíneo adecuado en los padres y las arterias distales 2,3. A pesar de su utilidad, la angiografía intraoperatoria se corre el riesgo de lesión arterial o un derrame cerebral y su amplia disponibilidad es limitada 4. En este reporte se describe el uso de una sonda de flujo ultrasónico para proporcionar evaluación cuantitativa intraoperatoria del flujo de sangre después del recorte quirúrgico de un aneurisma. La sonda de flujo Transonic utiliza la tecnología de tiempo de tránsito para medir el flujo sanguíneo. La sonda utiliza dos sensores para transmitir alternativamente y recibir la señal ultrasónica en ambas direcciones aguas arriba y aguas abajo con respecto al flujo de la sangre 5. El medidor de flujo se mide el tiempo de tránsito de una onda de ultrasonido en recorrer la distancia fija entre los transductores. La diferencia entre los tiempos de integración ascendente y descendente de tránsito es una medida del flujo sanguíneo. Las mediciones cuantitativas del flujo se realizan en los padres y los vasos distales antes del recorte de aneurisma y volvió a evaluar después de que el clip ha sido aplicada para garantizar la preservación del flujo sanguíneo 6-8. Si el flujo sanguíneo se reduce, el clip se puede reajustarse según sea necesario. Como se ve en este video, la obliteración quirúrgica de un aneurisma de arteria cerebral media y se realiza una evaluación cuantitativa del flujo sanguíneo con la sonda de ultrasonidos permite la confirmación del flujo preservado a través de las arterias distales que irrigan el cerebro, lo que permite evitar la complicación neurológica de la colocación impropia clip quirúrgico .

<ol>
	<li>Johnston, S. C., Selvin, S., Gress, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+burden,+trends,+and+demographics+of+mortality+from+subarachnoid+hemorrhage.">The burden, trends, and demographics of mortality from subarachnoid hemorrhage.</a> Neurology. 50, 1413-1418 (1998).</li><li>Alexander, T. D., Macdonald, R. L., Weir, B., Kowalczuk, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+angiography+in+cerebral+aneurysm+surgery:+a+prospective+study+of+100+craniotomies.">Intraoperative angiography in cerebral aneurysm surgery: a prospective study of 100 craniotomies.</a> Neurosurgery. 39, 10-17 (1996).</li><li>Tang, G., Cawley, C. M., Dion, J. E., Barrow, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+angiography+during+aneurysm+surgery:+a+prospective+evaluation+of+efficacy.">Intraoperative angiography during aneurysm surgery: a prospective evaluation of efficacy.</a> Journal of neurosurgery. 96, 993-999 (2002).</li><li>Katz, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+routine+intraoperative+angiography+in+the+surgical+treatment+of+cerebral+aneurysms+justified?+A+consecutive+series+of+147+aneurysms.">Is routine intraoperative angiography in the surgical treatment of cerebral aneurysms justified? A consecutive series of 147 aneurysms.</a> Neurosurgery. 58, 719-727 (2006).</li><li>Charbel, F. T., Hoffman, W. E., Misra, M., Ostergren, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonic+perivascular+flow+probe:+technique+and+application+in+neurosurgery.">Ultrasonic perivascular flow probe: technique and application in neurosurgery.</a> Neurological research. 20, 439-442 (1998).</li><li>Fagundes-Pereyra, W. J., Hoffman, W. E., Misra, M., Charbel, F. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clip+readjustment+in+aneurysm+surgery+after+flow+evaluation+using+the+ultrasonic+perivascular+probe:+case+report.+Arquivos+de+neuro-psiquiatria+63.">Clip readjustment in aneurysm surgery after flow evaluation using the ultrasonic perivascular probe: case report. Arquivos de neuro-psiquiatria 63.</a> , 339-344 (2005).</li><li>Amin-Hanjani, S., Meglio, G., Gatto, R., Bauer, A., Charbel, F. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+utility+of+intraoperative+blood+flow+measurement+during+aneurysm+surgery+using+an+ultrasonic+perivascular+flow+probe.">The utility of intraoperative blood flow measurement during aneurysm surgery using an ultrasonic perivascular flow probe.</a> Neurosurgery. 62, 1346-1353 (2008).</li><li>Amin-Hanjani, S., Charbel, F. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow-assisted+surgical+technique+in+cerebrovascular+surgery.">Flow-assisted surgical technique in cerebrovascular surgery.</a> Surgical neurology. 68, S4-11 (2007).</li></ol>

microsurgical clip obliteration of middle cerebral aneurysm using intraoperative flow assessment

Los aneurismas cerebrales son ensanchamiento o abombamiento anormal de un segmento localizada de un vaso sanguíneo intracraneal. Clipaje quirúrgico es un tratamiento importante para los aneurismas de que los intentos de excluir que la sangre fluya en el segmento de aneurisma de la embarcación mientras que preserva el flujo sanguíneo de manera normal. La colocación de clip de incorrecta puede provocar un aneurisma residual con la posibilidad de ruptura del aneurisma posterior o la oclusión parcial o total de las arterias distales que resulta en infarto cerebral. A continuación se describe el uso de una sonda de flujo ultrasónico para realizar una evaluación cuantitativa del flujo arterial antes y después de la colocación de microcirugía clip en la base de un aneurisma de la arteria cerebral media. Esta información ayuda a garantizar la reconstrucción aneurisma adecuada con la preservación del flujo normal de sangre distal.

Watch this Scientific Journal Video about Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment at JoVE.com

Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment

Descripción de la destrucción quirúrgica de un aneurisma cerebral utilizando una sonda de flujo por ultrasonido para evaluar el flujo arterial antes y después de la colocación de un aneurisma clip.

La obliteración de microcirugía Clip de Aneurisma Cerebral Media uso de la evaluación intraoperatoria de flujo

Cerebral aneurysms are abnormal widening or ballooning of a localized segment of an intracranial blood vessel.  Surgical clipping is an important ...

microsurgical-clip-obliteration-middle-cerebral-aneurysm-using

Research

JoVE Journal

Biology

13.6K vistas.  Havard Medical School, Massachusetts General Hospital. Descripción de la destrucción quirúrgica de un aneurisma cerebral utilizando una sonda de flujo por ultrasonido para evaluar el flujo arterial antes y después de la colocación de un aneurisma clip.

Video: Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment

Psychophysiological Stress Assessment Using Biofeedback 

In the last half century, research in biofeedback has shown the extent to which the human mind can influence the functioning of the autonomic nervous system, previously thought to be outside of conscious control. By letting people observe signals from their own bodies, biofeedback enables them to develop greater awareness of their physiological and psychological reactions, such as stress, and to learn to modify these reactions. Biofeedback practitioners can facilitate this process by assessing people s reactions to mildly stressful events and formulating a biofeedback-based treatment plan. During stress assessment the practitioner first records a baseline for physiological readings, and then presents the client with several mild stressors, such as a cognitive, physical and emotional stressor. Variety of stressors is presented in order to determine a person's stimulus-response specificity, or differences in each person's reaction to qualitatively different stimuli. This video will demonstrate the process of psychophysiological stress assessment using biofeedback and present general guidelines for treatment planning.

Psychophysiological Stress Assessment Using Biofeedback

In this video we will describe one method of assessing person's psychophysiological reaction to stress using biofeedback. We will also present general guidelines for treatment planning.

Evaluación psicofisiológica de estrés uso de Biofeedback

In the last half century, research in biofeedback has shown the extent to which the human mind can influence the functioning of the autonomic nervous ...

Investigación

Biología

Platelet Adhesion and Aggregation Under Flow using Microfluidic Flow Cells

Platelet aggregation occurs in response to vascular injury where the extracellular matrix below the endothelium has been exposed. The platelet adhesion cascade takes place in the presence of shear flow, a factor not accounted for in conventional (static) well-plate assays. This article reports on a platelet-aggregation assay utilizing a microfluidic well-plate format to emulate physiological shear flow conditions. Extracellular proteins, collagen I or von Willebrand factor are deposited within the microfluidic channel using active perfusion with a pneumatic pump. The matrix proteins are then washed with buffer and blocked to prepare the microfluidic channel for platelet interactions. Whole blood labeled with fluorescent dye is perfused through the channel at various flow rates in order to achieve platelet activation and aggregation. Inhibitors of platelet aggregation can be added prior to the flow cell experiment to generate IC50 dose response data.

The platelet adhesion cascade takes place in the presence of shear flow, a factor not accounted for in conventional (static) well-plate assays. This article reports on a platelet-aggregation assay utilizing a microfluidic well-plate format to emulate physiological shear flow conditions.

Adhesión y agregación plaquetaria bajo flujo con células de microfluidos de flujo

Platelet aggregation occurs in response to vascular injury where the extracellular matrix below the endothelium has been exposed. The platelet adhesion ...

Surgical Induction of Endolymphatic Hydrops by Obliteration of the Endolymphatic Duct

Surgical induction of endolymphatic hydrops (ELH) in the guinea pig by obliteration and obstruction of the endolymphatic duct is a well-accepted animal model of the condition and an important correlate for human Meniere's disease. In 1965, Robert Kimura and Harold Schuknecht first described an intradural approach for obstruction of the endolymphatic duct (Kimura 1965). Although effective, this technique, which requires penetration of the brain's protective covering, incurred an undesirable level of morbidity and mortality in the animal subjects. Consequently, Andrews and Bohmer developed an extradural approach, which predictably produces fewer of the complications associated with central nervous system (CNS) penetration.(Andrews and Bohmer 1989) 
The extradural approach described here first requires a midline incision in the region of the occiput to expose the underlying muscular layer. We operate only on the right side. After appropriate retraction of the overlying tissue, a horizontal incision is made into the musculature of the right occiput to expose the right temporo-occipital suture line. The bone immediately inferio-lateral the suture line (Fig 1) is then drilled with an otologic drill until the sigmoid sinus becomes visible. Medial retraction of the sigmoid sinus reveals the operculum of the endolymphatic duct, which houses the endolymphatic sac. Drilling medial to the operculum into the area of the endolymphatic sac reveals the endolymphatic duct, which is then packed with bone wax to produce obstruction and ultimately ELH. 
In the following weeks, the animal will demonstrate the progressive, fluctuating hearing loss and histologic evidence of ELH.

This video shows how to surgically obstruct the guinea pig's endolymphatic duct to produce endolymphatic hydrops.

Inducción quirúrgica de edema endolinfático por la obliteración del conducto endolinfático

Surgical induction of endolymphatic hydrops (ELH) in the guinea pig by obliteration and obstruction of the endolymphatic duct is a well-accepted animal ...

PAR-CliP - A Method to Identify Transcriptome-wide the Binding Sites of RNA Binding Proteins

RNA transcripts are subjected to post-transcriptional gene regulation by interacting with hundreds of RNA-binding proteins (RBPs) and microRNA-containing ribonucleoprotein complexes (miRNPs) that are often expressed in a cell-type dependently. To understand how the interplay of these RNA-binding factors affects the regulation of individual transcripts, high resolution maps of in vivo protein-RNA interactions are necessary1.
A combination of genetic, biochemical and computational approaches are typically applied to identify RNA-RBP or RNA-RNP interactions. Microarray profiling of RNAs associated with immunopurified RBPs (RIP-Chip)2 defines targets at a transcriptome level, but its application is limited to the characterization of kinetically stable interactions and only in rare cases3,4 allows to identify the RBP recognition element (RRE) within the long target RNA. More direct RBP target site information is obtained by combining in vivo UV crosslinking5,6 with immunoprecipitation7-9 followed by the isolation of crosslinked RNA segments and cDNA sequencing (CLIP)10. CLIP was used to identify targets of a number of RBPs11-17. However, CLIP is limited by the low efficiency of UV 254 nm RNA-protein crosslinking, and the location of the crosslink is not readily identifiable within the sequenced crosslinked fragments, making it difficult to separate UV-crosslinked target RNA segments from background non-crosslinked RNA fragments also present in the sample.
We developed a powerful cell-based crosslinking approach to determine at high resolution and transcriptome-wide the binding sites of cellular RBPs and miRNPs that we term PAR-CliP (Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation) (see Fig. 1A for an outline of the method). The method relies on the incorporation of photoreactive ribonucleoside analogs, such as 4-thiouridine (4-SU) and 6-thioguanosine (6-SG) into nascent RNA transcripts by living cells. Irradiation of the cells by UV light of 365 nm induces efficient crosslinking of photoreactive nucleoside-labeled cellular RNAs to interacting RBPs. Immunoprecipitation of the RBP of interest is followed by isolation of the crosslinked and coimmunoprecipitated RNA. The isolated RNA is converted into a cDNA library and deep sequenced using Solexa technology. One characteristic feature of cDNA libraries prepared by PAR-CliP is that the precise position of crosslinking can be identified by mutations residing in the sequenced cDNA. When using 4-SU, crosslinked sequences thymidine to cytidine transition, whereas using 6-SG results in guanosine to adenosine mutations. The presence of the mutations in crosslinked sequences makes it possible to separate them from the background of sequences derived from abundant cellular RNAs.
Application of the method to a number of diverse RNA binding proteins was reported in Hafner et al.18

RNA transcripts are subject to extensive posttranscriptional regulation that is mediated by a multitude of trans-acting RNA-binding proteins (RBPs). Here we present a generalizable method to identify precisely and on a transcriptome-wide scale the RNA binding sites of RBPs.

PAR-Clip - un método para identificar transcriptoma en todo los sitios de unión de las proteínas de unión a ARN

RNA transcripts are subjected to post-transcriptional gene regulation by interacting with hundreds of RNA-binding proteins (RBPs) and microRNA-containing ...

Flow Cytometry Purification of Mouse Meiotic Cells

The heterogeneous nature of cell types in the testis and the absence of meiotic cell culture models have been significant hurdles to the study of the unique differentiation programs that are manifest during meiosis. Two principal methods have been developed to purify, to varying degrees, various meiotic fractions from both adult and immature animals: elutriation or Staput (sedimentation) using BSA and/or percoll gradients. Both of these methods rely on cell size and density to separate meiotic cells1-5. Overall, except for few cell populations6, these protocols fail to yield sufficient purity of the numerous meiotic cell populations that are necessary for detailed molecular analyses. Moreover, with such methods usually one type of meiotic cells can be purified at a given time, which adds an extra level of complexity regarding the reproducibility and homogeneity when comparing meiotic cell samples.
Here, we describe a refined method that allows one to easily visualize, identify, and purify meiotic cells, from germ cells to round spermatids, using FACS combined with Hoechst 33342 staining7,8. This method provides an overall snapshot of the entire meiotic process and allows one to highly purify viable cells from most stage of meiosis. These purified cells can then be analyzed in detail for molecular changes that accompany progression through meiosis, for example changes in gene expression9,10and the dynamics of nucleosome occupancy at hotspots of meiotic recombination11.

An efficient method to obtain highly purified viable meiotic fractions from mouse testis is described, which combines a refined cell dissociation protocol with fluorescent activated cell sorting (FACS). This method takes advantage of differences in the DNA content and nuclear density of discrete meiotic fractions.

Citometría de flujo de purificación de las células de ratón meiótica

The heterogeneous nature of cell types in the testis and the absence of meiotic cell culture models have been significant hurdles to the study of the ...

Optimized Staining and Proliferation Modeling Methods for Cell Division Monitoring using Cell Tracking Dyes

Fluorescent cell tracking dyes, in combination with flow and image cytometry, are powerful tools with which to study the interactions and fates of different cell types in vitro and in vivo.1-5 Although there are literally thousands of publications using such dyes, some of the most commonly encountered cell tracking applications include monitoring of:
<ol>
	<li>stem and progenitor cell quiescence, proliferation and/or differentiation6-8</li>
	<li>antigen-driven membrane transfer9 and/or precursor cell proliferation3,4,10-18 and</li>
	<li>immune regulatory and effector cell function1,18-21.</li>
</ol>
Commercially available cell tracking dyes vary widely in their chemistries and fluorescence properties but the great majority fall into one of two classes based on their mechanism of cell labeling. "Membrane dyes", typified by PKH26, are highly lipophilic dyes that partition stably but non-covalently into cell membranes1,2,11. "Protein dyes", typified by CFSE, are amino-reactive dyes that form stable covalent bonds with cell proteins4,16,18. Each class has its own advantages and limitations. The key to their successful use, particularly in multicolor studies where multiple dyes are used to track different cell types, is therefore to understand the critical issues enabling optimal use of each class2-4,16,18,24.
The protocols included here highlight three common causes of poor or variable results when using cell-tracking dyes. These are:
<ol>
	<li>Failure to achieve bright, uniform, reproducible labeling. This is a necessary starting point for any cell tracking study but requires attention to different variables when using membrane dyes than when using protein dyes or equilibrium binding reagents such as antibodies.</li>
	<li>Suboptimal fluorochrome combinations and/or failure to include critical compensation controls. Tracking dye fluorescence is typically 102 - 103 times brighter than antibody fluorescence. It is therefore essential to verify that the presence of tracking dye does not compromise the ability to detect other probes being used.</li>
	<li>Failure to obtain a good fit with peak modeling software. Such software allows quantitative comparison of proliferative responses across different populations or stimuli based on precursor frequency or other metrics. Obtaining a good fit, however, requires exclusion of dead/dying cells that can distort dye dilution profiles and matching of the assumptions underlying the model with characteristics of the observed dye dilution profile.</li>
</ol>
Examples given here illustrate how these variables can affect results when using membrane and/or protein dyes to monitor cell proliferation.

Successful use of cell tracking dyes to monitor immune cell function and proliferation involves several critical steps. We describe methods for: 1) obtaining bright, uniform, reproducible label-ing with membrane dyes; 2) selecting fluorochromes and data acquisition conditions; and 3) choosing a model to quantify cell proliferation based on dye dilution.

Optimizado manchas y Proliferación métodos de modelización para la vigilancia del uso de tintes División Celular Celulares de seguimiento

Fluorescent cell tracking dyes, in combination with flow and image cytometry, are powerful tools with which to study the interactions and fates of ...

A Protocol for Using Gene Set Enrichment Analysis to Identify the Appropriate Animal Model for Translational Research

Recent studies that compared transcriptomic datasets of human diseases with datasets from mouse models using traditional gene-to-gene comparison techniques resulted in contradictory conclusions regarding the relevance of animal models for translational research. A major reason for the discrepancies between different gene expression analyses is the arbitrary filtering of differentially expressed genes. Furthermore, the comparison of single genes between different species and platforms often is limited by technical variance, leading to misinterpretation of the con/discordance between data from human and animal models. Thus, standardized approaches for systematic data analysis are needed. To overcome subjective gene filtering and ineffective gene-to-gene comparisons, we recently demonstrated that gene set enrichment analysis (GSEA) has the potential to avoid these problems. Therefore, we developed a standardized protocol for the use of GSEA to distinguish between appropriate and inappropriate animal models for translational research. This protocol is not suitable to predict how to design new model systems a-priori, as it requires existing experimental omics data. However, the protocol describes how to interpret existing data in a standardized manner in order to select the most suitable animal model, thus avoiding unnecessary animal experiments and misleading translational studies.

We provide a standardized protocol for the use of gene set enrichment analysis of transcriptomic data to identify an ideal mouse model for translational research. 
This protocol can be used with DNA microarray and RNA sequencing data and can further be extended to other omics data if data are available.

Un protocolo para el uso de gen Set enriquecimiento análisis para identificar el modelo Animal adecuado para la investigación traslacional

Recent studies that compared transcriptomic datasets of human diseases with datasets from mouse models using traditional gene-to-gene comparison ...

Microsurgical Obstruction of Testes Fusion in Spodoptera litura

Instead of using genetic methods like RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated endonuclease Cas9, a physical barrier was microsurgically inserted between the testes of Spodoptera litura to study the impact of this microsurgery on its growth and reproduction. After inserting aluminum foil between the testes, insect molting during metamorphosis proceeded normally. Insect growth and development were not remarkably altered; however, the number of sperm bundles changed if testes fusion was stopped by the microsurgery. These findings imply that blocking testicular fusion can influence male reproduction capability. The method can be further applied to interrupt communication between organs to study the function of specific signaling pathways. Compared to conventional surgery, microsurgery only requires freezing anesthetization, which is preferable to carbon dioxide anesthetization. Microsurgery also minimizes the surgery site area and facilitates wound healing. However, the selection of materials with specific functions needs further investigation. Avoiding tissue injury is crucial when making incisions during the operation.

Microsurgical Obstruction of Testes Fusion in Spodoptera litura

Aluminum foil was microsurgically inserted between the testes of Spodoptera litura to obstruct the fusion of testis. The procedure includes freezing, fixing, disinfection, incision, placing the barrier, suturing, postoperative feeding, and inspection. This approach provides a method to interfere with tissue formation.

Obstrucción microquirúrgica de la fusión de testículos en Spodoptera litura

Instead of using genetic methods like RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated ...

Quantification of Cellular Densities and Antigenic Properties using Magnetic Levitation

The described method was developed based on the principles of magnetic levitation, which separates cells and particles based on their density and magnetic properties. Density is a cell type identifying property, directly related to its metabolic rate, differentiation, and activation status. Magnetic levitation allows a one-step approach to successfully separate, image and characterize circulating blood cells, and to detect anemia, sickle cell disease, and circulating tumor cells based on density and magnetic properties. This approach is also amenable to detecting soluble antigens present in a solution by using sets of low- and high-density beads coated with capture and detection antibodies, respectively. If the antigen is present in solution, it will bridge the two sets&#160;of beads, generating a new bead-bead complex, which will levitate in between the rows of antibody-coated beads. Increased concentration of the target antigen in solution will generate a larger number of bead-bead complexes when compared to lower concentrations of antigen, thus allowing for quantitative measurements of the target antigen. Magnetic levitation is advantageous to other methods due to its decreased sample preparation time and lack of dependance on classical readout methods. The image generated is easily captured and analyzed using a standard microscope or mobile device, such as a smartphone or a tablet.

This paper describes a magnetic levitation-based method that can specifically detect the presence of antigens, either soluble or membrane-bound, by quantifying changes in the levitation height of capture beads with fixed densities.

Cuantificación de las densidades celulares y propiedades antigénicas mediante levitación magnética

The described method was developed based on the principles of magnetic levitation, which separates cells and particles based on their density and magnetic ...

Functional Assessment of Kinesin-7 CENP-E in Spermatocytes Using In Vivo Inhibition, Immunofluorescence and Flow Cytometry

In eukaryotes, meiosis is essential for genome stability and genetic diversity in sexual reproduction. Experimental analyses of spermatocytes in testes are critical for the investigations of spindle assembly and chromosome segregation in male meiotic division. The mouse spermatocyte is an ideal model for mechanistic studies of meiosis, however, the effective methods for the analyses of spermatocytes are lacking. In this article, a practical and efficient method for the in vivo inhibition of kinesin-7 CENP-E in mouse spermatocytes is reported. A detailed procedure for testicular injection of a specific inhibitor GSK923295 through abdominal surgery in 3-week-old mice is presented. Furthermore, described here is a series of protocols for tissue collection and fixation, hematoxylin-eosin staining, immunofluorescence, flow cytometry and transmission electron microscopy. Here we present an in vivo inhibition model via abdominal surgery and testicular injection, that could be a powerful technique to study male meiosis. We also demonstrate that CENP-E inhibition results in chromosome misalignment and metaphase arrest in primary spermatocytes during meiosis I. Our in vivo inhibition method will facilitate mechanistic studies of meiosis, serve as a useful method for genetic modifications of male germ lines, and shed a light on future clinical applications.

Functional Assessment of Kinesin-7 CENP-E in Spermatocytes Using In Vivo Inhibition, Immunofluorescence and Flow Cytometry

This article reports an in vivo inhibition of CENP-E through abdominal surgery and testicular injection of GSK923295, a valuable model for male meiotic division. Using the immunofluorescence, flow cytometry and transmission electron microscopy assays, we show that CENP-E inhibition results in chromosome misalignment and genome instability in mouse spermatocytes.

Evaluación funcional de la quinesina-7 CENP-E en espermatocitos mediante inhibición in vivo , inmunofluorescencia y citometría de flujo

In eukaryotes, meiosis is essential for genome stability and genetic diversity in sexual reproduction. Experimental analyses of spermatocytes in testes ...