Articles de revues : « Microscopie cellulaire »

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Laporte, Marine H., Éloïse Bertiaux, Virginie Hamel et Paul Guichard. « L’organisation native de la cellule révélée grâce à la cryo-microscopie à expansion ». médecine/sciences 39, n^o 4 (avril 2023) : 351–58. http://dx.doi.org/10.1051/medsci/2023052.

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La plupart des techniques d’imagerie cellulaire, telles que la microscopie photonique ou la microscopie électronique, nécessitent que l’échantillon biologique soit préalablement fixé par des agents chimiques, une étape qui est connue pour endommager l’organisation sub-cellulaire. Pour pallier à ce problème, la cryo-fixation, inventée il y a plus de 40 ans, consiste à vitrifier les échantillons biologiques afin de préserver leur état natif. Cette méthode n’avait cependant été que très peu utilisée en microscopie photonique. Dans cette revue, nous présentons en détail la microscopie d’expansion, une technique de super-résolution développée récemment et qui, couplée à la cryo-fixation, permet de visualiser l’architecture cellulaire au plus près de son état natif.

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Méry, Annabelle, et Michel Pucéat. « Visualisation de la différenciation cellulaire cardiaque par microscopie confocale ». Journal de la Société de Biologie 198, n^o 2 (2004) : 145–51. http://dx.doi.org/10.1051/jbio/2004198020145.

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Arizono, Misa, et U. Valentin Nägerl. « Plus vive, plus nette : la microscopie STED du cerveau ». Photoniques, n^o 114 (2022) : 36–39. http://dx.doi.org/10.1051/photon/202111436.

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La microscopie à super-résolution (SRM) désigne une nouvelle catégorie de techniques de microscopie optique qui permettent de surmonter la barrière de diffraction classique,- barrière qui a rendu difficile l’observation des structures et des activités qui constituent la base de la vie cellulaire biologique. La microscopie STED, qui est l'une des techniques SRM, a attiré l'attention des neurobiologistes, car elle permet de révéler la nanostructure des cellules cérébrales non seulement dans une boîte de Pétri, mais aussi à l'intérieur du tissu cérébral réel, voire dans le cerveau intact in vivo.

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Jouchet, Pierre, Abigail Illand, Guillaume Dupuis, Emmanuel Fort et Sandrine Lévêque-Fort. « Dépasser la limite de diffraction en microscopie de fluorescence ». Photoniques, n^o 108 (mai 2021) : 44–48. http://dx.doi.org/10.1051/photon/202110845.

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La microscopie de fluorescence est un outil de référence dans l’étude des systèmes biologiques, alliant la spécificité offerte par la fluorescence et la possibilité d’un suivi non invasif en milieu vivant. Cependant comme l’ensemble des techniques de microscopie, elle est soumise au phénomène de diffraction introduit par l’objectif, qui limite la résolution de l’instrument. Ce texte présente les différentes méthodes permettant de dépasser cette contrainte en associant développement instrumental en optique et contrôle de la photophysique des fluorophores afin de révéler l’organisation cellulaire à l’échelle nanométrique.

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Sentenac, Anne. « Améliorer la résolution de la microscopie optique de fluorescence ». Photoniques, n^o 114 (2022) : 45–50. http://dx.doi.org/10.1051/photon/202111445.

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La microscopie de fluorescence est un outil majeur, en particulier pour étudier le fonctionnement du vivant au niveau cellulaire, mais sa résolution est limitée à quelques centaines de nanomètres. Ces vingt dernières années, différentes techniques ont été proposées pour descendre la résolution sous la barre des 100 nm. Cet article essaie de présenter leurs principes de manière unifiée.

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Giocondi, Marie-Cécile, Pierre Emmanuel Milhiet, Eric Lesniewska et Christian Le Grimellec. « Microscopie à force atomique : de l’imagerie cellulaire à la manipulation moléculaire ». médecine/sciences 19, n^o 1 (janvier 2003) : 92–99. http://dx.doi.org/10.1051/medsci/200319192.

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Illand, Abigail, Pierre Jouchet, Emmanuel Fort et Sandrine Lévêque-Fort. « Localisation nanométrique de molécules uniques par modulation du signal de fluorescence ». Photoniques, n^o 114 (2022) : 30–35. http://dx.doi.org/10.1051/photon/202111430.

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La microscopie de localisation de molécules individuelles permet de dépasser la limite de diffraction, révélant ainsi l’organisation cellulaire à l’échelle nanométrique. Cette méthode reposant sur l’analyse spatiale du signal émis par les molécules, reste souvent limitée à l’observation d’objets biologiques à de faibles profondeurs, ou très peu aberrants. Nous montrons ici que l’introduction d’un paramètre temporel dans le processus de localisation via l’introduction d’une excitation modulée permet d’adresser ces limitations.

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Lévy, Daniel, Aurélie Di Cicco, Aurélie Bertin et Manuela Dezi. « La cryo-microscopie électronique révèle une nouvelle vision de la cellule et de ses composants ». médecine/sciences 37, n^o 4 (avril 2021) : 379–85. http://dx.doi.org/10.1051/medsci/2021034.

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La cryo-microscopie électronique (cryo-EM) est une technique d’imagerie du vivant qui prend désormais une place prépondérante en biologie structurale, avec des retombées en biologie cellulaire et du développement, en bioinformatique, en biomédecine ou en physique de la cellule. Elle permet de déterminer des structures de protéines purifiées in vitro ou au sein des cellules. Cette revue décrit les principales avancées récentes de la cryo-EM, illustrées par des exemples d’élucidation de structures de protéines d’intérêt en biomédecine, et les pistes de développements futurs.

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Perrot, J. L., B. Labeille et F. Cambazard. « Visualisation de la nécrose cellulaire d’un carcinome basocellulaire traité par photothérapie dynamique en microscopie confocale ». Annales de Dermatologie et de Vénéréologie 138, n^o 12 (décembre 2011) : A211. http://dx.doi.org/10.1016/j.annder.2011.10.211.

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Perrot, J. L., A. Biron, E. Couty, L. Tognetti, C. Couzan, R. Rossi, P. Rubegni et E. Cinotti. « Premiers cas de corrélation parfaite à l’échelle cellulaire entre image de microscopie confocale in vivo et dermatoscopie ». Annales de Dermatologie et de Vénéréologie 145, n^o 12 (décembre 2018) : S186. http://dx.doi.org/10.1016/j.annder.2018.09.261.

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Nawrotek, Agata, et Jacqueline Cherfils. « Une moisson de nouvelles structures de mTORC1 ». médecine/sciences 37, n^o 4 (avril 2021) : 372–78. http://dx.doi.org/10.1051/medsci/2021033.

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mTORC1 est un acteur central de la croissance cellulaire, un processus étroitement régulé par la disponibilité de nutriments et qui contrôle diverses étapes du métabolisme dans la cellule normale et au cours de maladies, comme les cancers. mTORC1 est un complexe multiprotéique de grande taille constitué de nombreuses sous-unités, parmi lesquelles deux types de GTPases, Rag et RheB, contrôlent directement sa localisation membranaire et son activité kinase. Dans cette revue, nous faisons le point sur une moisson de structures récentes, déterminées pour la plupart par cryo-microscopie électronique, qui sont en passe de reconstituer le puzzle de l’architecture de mTORC1. Nous discutons ce que ces structures révèlent sur le rôle des GTPases, et ce que leur connaissance ouvre comme perspectives pour comprendre comment mTORC1 fonctionne à la membrane du lysosome.

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Fakhfakh, Emna, Christian Le Goff, Emmanuel Albina, S. Zekri, C. Seghaier, C. Odisseev, M. H. Jaafoura et Salah Hammami. « Isolement et étude moléculaire de souches des virus de la clavelée et de l’ecthyma contagieux en Tunisie ». Revue d’élevage et de médecine vétérinaire des pays tropicaux 58, n^o 1-2 (1 janvier 2005) : 7. http://dx.doi.org/10.19182/remvt.9943.

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L’élevage des petits ruminants est touché par plusieurs pathologies infectieuses cutanées. Ainsi, la clavelée et l’ecthyma contagieux représentent deux maladies virales importantes à étudier de part leur allure enzootique et la perte économique qu’elles entraînent. L’objectif de ce travail a été l’isolement en Tunisie de souches virales responsables de ces deux pathologies cutanées et leur caractérisation par l’application et la comparaison de méthodes de diagnostic. La microscopie électronique a été utilisée pour une étude morphologique externe et interne des différentes souches isolées sur culture cellulaire. L’identification par PCR a concerné le gène de la thymidine kinase (TK), le gène de l’analogue du récepteur des chimiokines (CXCR-2) et le gène de la protéine P42K présente chez les Parapoxvirus. L’identification moléculaire très sensible et très spécifique des souches de Capripoxvirus a été complétée par une analyse phylogénétique.

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Dufour, Pascal, Suzie Dufour, Annie Castonguay, Nathalie McCarthy et Yves De Koninck. « Microscopie à deux photons pour l’imagerie cellulaire fonctionnelle : avantages et enjeux ou Un photon c’est bien… mais deux c’est mieux ! » médecine/sciences 22, n^o 10 (octobre 2006) : 837–44. http://dx.doi.org/10.1051/medsci/20062210837.

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Chen, Xiaodong, Bin Zheng et Hong Liu. « Optical and Digital Microscopic Imaging Techniques and Applications in Pathology ». Analytical Cellular Pathology 34, n^o 1-2 (2011) : 5–18. http://dx.doi.org/10.1155/2011/150563.

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The conventional optical microscope has been the primary tool in assisting pathological examinations. The modern digital pathology combines the power of microscopy, electronic detection, and computerized analysis. It enables cellular-, molecular-, and genetic-imaging at high efficiency and accuracy to facilitate clinical screening and diagnosis. This paper first reviews the fundamental concepts of microscopic imaging and introduces the technical features and associated clinical applications of optical microscopes, electron microscopes, scanning tunnel microscopes, and fluorescence microscopes. The interface of microscopy with digital image acquisition methods is discussed. The recent developments and future perspectives of contemporary microscopic imaging techniques such as three-dimensional and in vivo imaging are analyzed for their clinical potentials.

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Mwamengele, G. L. M., et S. Larsen. « L’ultrastructure de lamicrovasculature cérébrale de chèvres infectées expérimentalement avec Cowdria ruminantium ». Revue d’élevage et de médecine vétérinaire des pays tropicaux 46, n^o 1-2 (1 janvier 1993) : 245. http://dx.doi.org/10.19182/remvt.9372.

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Afin d’étudier les lésions de la microvasculature cérébrale dans la cowdriose, 14 chèvres tanzaniennes ont été infectées par inoculation intraveineuse avec le stock Ball-3 de Cowdria ruminantium. Elles ont été suivies sur le plan clinique pendant la période d’incubation et la réaction fébrile, et sacrifiées lorsque les températures ont commencé à baisser. Cinq chèvres saines ont été utilisées pour déterminer la meilleure procédure pour la fixation du cerveau par perfusion et pour servir de témoins. La perfusion a été effectuée par l’artère carotide sous anesthésie générale au pentobarbitone, utilisant du glutaraldehyde de pH 7,4 à 3 p.100, à 500 mOsm. Des prélèvements de tissu cérébral ont été pris pour microscopie classique et électronique. Des signes variables de désordres du système nerveux central et un hydropéricarde peu important se sont développés chez toutes les chèvres infectées. Deux changements neuropathologiques différents ont été observés : des colonies de Cowdria dans des cellules endothéliales vasculaires, sans autres changements, et des petites infiltrations périvasculaires de cellules mononucléaires. Aucun signe de vasculite ou d’une perméabilité vasculaire anormale n’a été observé. Plusieurs phagocytes périvasculaires renfermaient des inclusions cytoplasmiques inhabituelles, se présentant comme des agrégations de particules irrégulièrement arrondies, associées à une membrane, de 0,25 à 0,4 µm de diamètre, ayant dans quelques cas une structure interne évocatrice de mitochondries partiellement dégradées. Néanmoins, ces agrégations ne semblaient pas enfermées de façon convaincante à l’intérieur de membranes, comme il est à à prévoir en cas d’autophagocytose. Une autre interprétation hypothétique est qu’elles représentent des stades abortifs de C. ruminantium qui tentent de se développer en dehors des vaisseaux et qu’une réponse immunitaire cellulaire, développée pendant et après la période d’incubation, limite ce deuxième cycle dans l’hôte et provoque des infiltrations périvasculaires mononucléaires.

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De Meyts, Pierre. « Le récepteur de l’insuline a 50 ans – Revue des progrès accomplis ». Biologie Aujourd’hui 216, n^o 1-2 (2022) : 7–28. http://dx.doi.org/10.1051/jbio/2022007.

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L’isolement de l’insuline du pancréas et sa purification à un degré suffisant pour permettre son administration à des patients atteints de diabète de type 1 furent accomplis il y a 100 ans à l’Université de Toronto par Banting, Best, Collip et McLeod et représentent sans conteste une des plus grandes révolutions thérapeutiques en médecine, reconnue par l’attribution du Prix Nobel de Physiologie ou Médecine en 1923 à Banting et McLeod. Les retombées cliniques furent rapides ainsi que l’internationalisation de sa production commerciale. Les retombées en matière de recherche fondamentale furent beaucoup plus lentes, en particulier en ce qui concerne les mécanismes moléculaires d’action de l’insuline sur ses cellules cibles. Presque un demi-siècle s’écoula avant la détermination de la structure tri-dimensionnelle de l’insuline en 1969 et la caractérisation de son récepteur cellulaire en 1970–1971. Le fait que le récepteur de l’insuline soit une enzyme appelée tyrosine kinase ne fut démontré que dans les années 1982–1985, et la structure cristallographique du domaine kinase intracellulaire fut déterminée dix ans plus tard. La structure cristallographique du premier substrat intracellulaire de la kinase (IRS-1) en 1991 ouvrira la voie à l’élucidation des voies de signalisation intracellulaires. Il faudra 15 ans de plus avant l’obtention de la structure cristallographique du domaine extracellulaire du récepteur (en l’absence d’insuline) en 2006. Depuis, la détermination de la structure du complexe insuline-récepteur dans les états inactif et activé a fait d’énormes progrès, en particulier grâce aux améliorations récentes dans les pouvoirs de résolution de la cryo-microscopie électronique. Je passerai ici en revue les étapes du développement du concept de récepteur hormonal, et de nos connaissances sur la structure et le mécanisme moléculaire d’activation du récepteur de l’insuline.

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Martone, Maryann E. « Bridging the Resolution Gap : Correlated 3D Light and Electron Microscopic Analysis of Large Biological Structures ». Microscopy and Microanalysis 5, S2 (août 1999) : 526–27. http://dx.doi.org/10.1017/s1431927600015956.

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One class of biological structures that has always presented special difficulties to scientists interested in quantitative analysis is comprised of extended structures that possess fine structural features. Examples of these structures include neuronal spiny dendrites and organelles such as the Golgi apparatus and endoplasmic reticulum. Such structures may extend 10's or even 100's of microns, a size range best visualized with the light microscope, yet possess fine structural detail on the order of nanometers that require the electron microscope to resolve. Quantitative information, such as surface area, volume and the micro-distribution of cellular constituents, is often required for the development of accurate structural models of cells and organelle systems and for assessing and characterizing changes due to experimental manipulation. Performing estimates of such quantities from light microscopic data can result in gross inaccuracies because the contribution to total morphometries of delicate features such as membrane undulations and excrescences can be quite significant. For example, in a recent study by Shoop et al, electron microscopic analysis of cultured chick ciliary ganglion neurons showed that spiny projections from the plasmalemma that were not well resolved in the light microscope effectively doubled the surface area of these neurons.While the resolution provided by the electron microscope has yet to be matched or replaced by light microscopic methods, one drawback of electron microscopic analysis has always been the relatively small sample size and limited 3D information that can be obtained from samples prepared for conventional transmission electron microscopy. Reconstruction from serial electron micrographs has provided one way to circumvent this latter problem, but remains one of the most technically demanding skills in electron microscopy. Another approach to 3D electron microscopic imaging is high voltage electron microscopy (HVEM). The greater accelerating voltages of HVEM's allows for the use of much thicker specimens than conventional transmission electron microscopes.

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Terryn, C., J. Michel, L. Kilian, P. Bonhomme et G. Balossier. « Cryométhodes en microscopie électronique à balayage en transmission (MEBT) appliquées a l'analyse cellulaire à l'échelle submicrométrique : mesure locale en eau par imagerie en champ sombre quantitative afin de déterminer des concentrations élémentaires dans l'état physiologique ». ITBM-RBM 22, n^o 6 (décembre 2001) : 362–70. http://dx.doi.org/10.1016/s1297-9562(01)90011-7.

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Al-Rimawi, H., F. Al-Bagdadi et N. Hailat. « Ultrastructural characterization of acute lymphoblastic leukaemia in children in Irbid, Jordan ». Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994) : 240–41. http://dx.doi.org/10.1017/s0424820100168931.

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A formal scheme for the characterization of acute leukaemia on light microscopic morphological adaptation (FAB) has been proposed by a group of French, American and British haematologists. Acute leukaemia has been reported with unclassifiable morphology and undifferentiated cytochemistry by FAB. The application of the light microscope for cellular diagnosis is not very reliable, due to the fact that the key predominant cell being sought for the diagnosis is poorly differentiated. However, we do agree that cellular differentiation by light microscopy, which is solely based on morphological criteria as a diagnosis evidence is often lacks accuracy. This statement is clear indication of the light microscopic limitation, to identify the morphological changes in comparison with the electron microscope. We suggest electron microscopic conformation might be necessary for light microscopic diagnosis. Five patients 5-12 years old were clinically suspected as leukaemia, were presented to Princess Basmah Teaching Hospital paediatric section for diagnosis. FAB classification which is based on morphological and biochemical criteria was used for diagnosis through bone marrow aspiration.

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Martone, Maryann E., Andrea Thor, Stephen J. Young et Mark H. Ellisman. « Correlated 3D Light and Electron Microscopy of Large, Complex Structures : Analysis of Transverse Tubules in Heart Failure ». Microscopy and Microanalysis 4, S2 (juillet 1998) : 440–41. http://dx.doi.org/10.1017/s1431927600022327.

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Light microscopic imaging has experienced a renaissance in the past decade or so, as new techniques for high resolution 3D light microscopy have become readily available. Light microscopic (LM) analysis of cellular details is desirable in many cases because of the flexibility of staining protocols, the ease of specimen preparation and the relatively large sample size that can be obtained compared to electron microscopic (EM) analysis. Despite these advantages, many light microscopic investigations require additional analysis at the electron microscopic level to resolve fine structural features.High voltage electron microscopy allows the use of relatively thick sections compared to conventional EM and provides the basis for excellent new methods to bridge the gap between microanatomical details revealed by LM and EM methods. When combined with electron tomography, investigators can derive accurate 3D data from these thicker specimens. Through the use of correlated light and electron microscopy, 3D reconstructions of large cellular or subcellular structures can be obtained with the confocal microscope,

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Okumura, Dai, Nobutada Ohno et Hirohisa Noguchi. « GSW0454 Microscopic buckling and macroscopic instability of periodic cellular solids ». Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2003.2 (2003) : _GSW0454–1—_GSW0454–6. http://dx.doi.org/10.1299/jsmeatem.2003.2._gsw0454-1.

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Eminizer, Margaret, Melinda Nagy, Elizabeth L. Engle, Sigfredo Soto-Diaz, Andrew Jorquera, Jeffrey S. Roskes, Benjamin F. Green, Richard Wilton, Janis M. Taube et Alexander S. Szalay. « Comparing and Correcting Spectral Sensitivities between Multispectral Microscopes : A Prerequisite to Clinical Implementation ». Cancers 15, n^o 12 (8 juin 2023) : 3109. http://dx.doi.org/10.3390/cancers15123109.

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Multispectral, multiplex immunofluorescence (mIF) microscopy has been used to great effect in research to identify cellular co-expression profiles and spatial relationships within tissue, providing a myriad of diagnostic advantages. As these technologies mature, it is essential that image data from mIF microscopes is reproducible and standardizable across devices. We sought to characterize and correct differences in illumination intensity and spectral sensitivity between three multispectral microscopes. We scanned eight melanoma tissue samples twice on each microscope and calculated their average tissue region flux intensities. We found a baseline average standard deviation of 29.9% across all microscopes, scans, and samples, which was reduced to 13.9% after applying sample-specific corrections accounting for differences in the tissue shown on each slide. We used a basic calibration model to correct sample- and microscope-specific effects on overall brightness and relative brightness as a function of the image layer. We tested the generalizability of the calibration procedure and found that applying corrections to independent validation subsets of the samples reduced the variation to 2.9 ± 0.03%. Variations in the unmixed marker expressions were reduced from 15.8% to 4.4% by correcting the raw images to a single reference microscope. Our findings show that mIF microscopes can be standardized for use in clinical pathology laboratories using a relatively simple correction model.

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Ekstrom, James. « Digital Imaging in K-12 Biology ». Microscopy Today 10, n^o 6 (novembre 2002) : 32–35. http://dx.doi.org/10.1017/s1551929500058508.

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K-12 instruction in biology has traditionally taken a very descriptive approach. This is in marked contrast to quantitative as well as qualitative way of looking at things in physics and chemistry. This qualitative/descriptive approach even extends into the iaboratory portion of the biological course. One way to introduce a more quantitative approach is in the microscopy portion of the biology curriculum. Because cellular structure is primarily a microscopic province It makes sense to introduce students to the different microscopic tools such as TEM and SEM, as well as the light microscope that are used to investigate cell structure.

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Mao, Hong, Robin Diekmann, Hai Po H. Liang, Victoria C. Cogger, David G. Le Couteur, Glen P. Lockwood, Nicholas J. Hunt et al. « Cost-efficient nanoscopy reveals nanoscale architecture of liver cells and platelets ». Nanophotonics 8, n^o 7 (9 juillet 2019) : 1299–313. http://dx.doi.org/10.1515/nanoph-2019-0066.

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AbstractSingle-molecule localization microscopy (SMLM) provides a powerful toolkit to specifically resolve intracellular structures on the nanometer scale, even approaching resolution classically reserved for electron microscopy (EM). Although instruments for SMLM are technically simple to implement, researchers tend to stick to commercial microscopes for SMLM implementations. Here we report the construction and use of a “custom-built” multi-color channel SMLM system to study liver sinusoidal endothelial cells (LSECs) and platelets, which costs significantly less than a commercial system. This microscope allows the introduction of highly affordable and low-maintenance SMLM hardware and methods to laboratories that, for example, lack access to core facilities housing high-end commercial microscopes for SMLM and EM. Using our custom-built microscope and freely available software from image acquisition to analysis, we image LSECs and platelets with lateral resolution down to about 50 nm. Furthermore, we use this microscope to examine the effect of drugs and toxins on cellular morphology.

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Lab, Max J., Anamika Bhargava, Peter T. Wright et Julia Gorelik. « The scanning ion conductance microscope for cellular physiology ». American Journal of Physiology-Heart and Circulatory Physiology 304, n^o 1 (1 janvier 2013) : H1—H11. http://dx.doi.org/10.1152/ajpheart.00499.2012.

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The quest for nonoptical imaging methods that can surmount light diffraction limits resulted in the development of scanning probe microscopes. However, most of the existing methods are not quite suitable for studying biological samples. The scanning ion conductance microscope (SICM) bridges the gap between the resolution capabilities of atomic force microscope and scanning electron microscope and functional capabilities of conventional light microscope. A nanopipette mounted on a three-axis piezo-actuator, scans a sample of interest and ion current is measured between the pipette tip and the sample. The feedback control system always keeps a certain distance between the sample and the pipette so the pipette never touches the sample. At the same time pipette movement is recorded and this generates a three-dimensional topographical image of the sample surface. SICM represents an alternative to conventional high-resolution microscopy, especially in imaging topography of live biological samples. In addition, the nanopipette probe provides a host of added modalities, for example using the same pipette and feedback control for efficient approach and seal with the cell membrane for ion channel recording. SICM can be combined in one instrument with optical and fluorescent methods and allows drawing structure-function correlations. It can also be used for precise mechanical force measurements as well as vehicle to apply pressure with precision. This can be done on living cells and tissues for prolonged periods of time without them loosing viability. The SICM is a multifunctional instrument, and it is maturing rapidly and will open even more possibilities in the near future.

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Brama, Elisabeth, Christopher J. Peddie, Gary Wilkes, Yan Gu, Lucy M. Collinson et Martin L. Jones. « ultraLM and miniLM : Locator tools for smart tracking of fluorescent cells in correlative light and electron microscopy ». Wellcome Open Research 1 (13 décembre 2016) : 26. http://dx.doi.org/10.12688/wellcomeopenres.10299.1.

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In-resin fluorescence (IRF) protocols preserve fluorescent proteins in resin-embedded cells and tissues for correlative light and electron microscopy, aiding interpretation of macromolecular function within the complex cellular landscape. Dual-contrast IRF samples can be imaged in separate fluorescence and electron microscopes, or in dual-modality integrated microscopes for high resolution correlation of fluorophore to organelle. IRF samples also offer a unique opportunity to automate correlative imaging workflows. Here we present two new locator tools for finding and following fluorescent cells in IRF blocks, enabling future automation of correlative imaging. The ultraLM is a fluorescence microscope that integrates with an ultramicrotome, which enables ‘smart collection’ of ultrathin sections containing fluorescent cells or tissues for subsequent transmission electron microscopy or array tomography. The miniLM is a fluorescence microscope that integrates with serial block face scanning electron microscopes, which enables ‘smart tracking’ of fluorescent structures during automated serial electron image acquisition from large cell and tissue volumes.

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Wicks, Laura C., Gemma S. Cairns, Jacob Melnyk, Scott Bryce, Rory R. Duncan et Paul A. Dalgarno. « EnLightenment : High resolution smartphone microscopy as an educational and public engagement platform ». Wellcome Open Research 2 (6 novembre 2017) : 107. http://dx.doi.org/10.12688/wellcomeopenres.12841.1.

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We developed a simple, cost-effective smartphone microscopy platform for use in educational and public engagement programs. We demonstrated its effectiveness, and potential for citizen science through a national imaging initiative, EnLightenment. The cost effectiveness of the instrument allowed for the program to deliver over 500 microscopes to more than 100 secondary schools throughout Scotland, targeting 1000’s of 12-14 year olds. Through careful, quantified, selection of a high power, low-cost objective lens, our smartphone microscope has an imaging resolution of microns, with a working distance of 3 mm. It is therefore capable of imaging single cells and sub-cellular features, and retains usability for young children. The microscopes were designed in kit form and provided an interdisciplinary educational tool. By providing full lesson plans and support material, we developed a framework to explore optical design, microscope performance, engineering challenges on construction and real-world applications in life sciences, biological imaging, marine biology, art, and technology. A national online imaging competition framed EnLightenment; with over 500 high quality images submitted of diverse content, spanning multiple disciplines. With examples of cellular and sub-cellular features clearly identifiable in some submissions, we show how young public can use these instruments for research-level imaging applications, and the potential of the instrument for citizen science programs.

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Wicks, Laura C., Gemma S. Cairns, Jacob Melnyk, Scott Bryce, Rory R. Duncan et Paul A. Dalgarno. « EnLightenment : High resolution smartphone microscopy as an educational and public engagement platform ». Wellcome Open Research 2 (3 mai 2018) : 107. http://dx.doi.org/10.12688/wellcomeopenres.12841.2.

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We developed a simple, cost-effective smartphone microscopy platform for use in educational and public engagement programs. We demonstrated its effectiveness, and potential for citizen science through a national imaging initiative, EnLightenment. The cost effectiveness of the instrument allowed for the program to deliver over 500 microscopes to more than 100 secondary schools throughout Scotland, targeting 1000’s of 12-14 year olds. Through careful, quantified, selection of a high power, low-cost objective lens, our smartphone microscope has an imaging resolution of microns, with a working distance of 3 mm. It is therefore capable of imaging single cells and sub-cellular features, and retains usability for young children. The microscopes were designed in kit form and provided an interdisciplinary educational tool. By providing full lesson plans and support material, we developed a framework to explore optical design, microscope performance, engineering challenges on construction and real-world applications in life sciences, biological imaging, marine biology, art, and technology. A national online imaging competition framed EnLightenment; with over 500 high quality images submitted of diverse content, spanning multiple disciplines. With examples of cellular and sub-cellular features clearly identifiable in some submissions, we show how young public can use these instruments for research-level imaging applications, and the potential of the instrument for citizen science programs.

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Kam, Zvi. « Microscopic imaging of cells ». Quarterly Reviews of Biophysics 20, n^o 3-4 (novembre 1987) : 201–59. http://dx.doi.org/10.1017/s0033583500004182.

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The microworld was revealed to investigators through a glass bead or a hanging water droplet long before optics was understood. The cellular structure of plants was well resolved by such simple magnifying glasses, van Leeuwenhoek, the Dutch merchant and amateur microscopist, was the first to report to the English Royal Society his observations of bacteria with his single-lens microscope in 1665.

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Yushin, Vladimir, et August Coomans. « Ultrastructure of sperm development in the free-living marine nematodes of the family Chromadoridae (Chromadorida : Chromadorina) ». Nematology 2, n^o 3 (2000) : 285–96. http://dx.doi.org/10.1163/156854100509150.

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AbstractSpermatogenesis in two species of free-living marine nematodes from the family Chromadoridae (Panduripharynx pacifica and Euchromadora robusta) was studied electron-microscopically. The spermatogonia of both species are undifferentiated polygonal cells with a large nucleus surrounded by a small amount of cytoplasm. In P. pacifica the cytoplasm of spermatocytes contains many Golgi bodies, cisternae of RER, ribosomes, mitochondria and dense spherical bodies. Filamentous material is accumulated in spermatids, which contain only mitochondria and a fragmented (or lobed) nucleus devoid of the nuclear envelope. The immature sperm resembles the late spermatid: its central filamentous area is surrounded by chromatine particles and occasional mitochondria. The immature sperm plasma membrane forms deep infoldings. Mature spermatozoa from the uterus consist of a small main cell body (MCB) bearing a prominent pseudopod filled with cytoskeleton filaments. The MCB contains a nucleus and mitochondria. Spermatogenesis in E. robusta (studied only in testes) resembles that described for P. pacifica, but spermatocytes of E. robusta show much lower metabolic activity and, as a result, a smaller mass of filamentous material is stored in the spermatids and immature sperm. The spermatozoa of P. pacifica and the immature sperm of E. robusta have the main ultrastructural features characteristic for nematodes (amoeboid nature, absence of axoneme, acrosome and nuclear envelope). No aberrant organelles special for many nematode sperm (membranous organelles, paracrystalline fibrous bodies and their complexes) were found during sperm development of the chromadorids studied. In this respect their spermatogenesis differs significantly from that in secernents and monhysterids.La spermatogenèse a été étudiée en microscopie électronique à transmission chez deux espèces de nématodes libres marins (Panduripharynx pacifica et Euchromadora robusta) de la famille des Chromadoridae. Les spermatogonies, chez les deux espèces, sont des cellules indifférenciées avec un grand noyau entouré d'une petite quantité de cytoplasme. Chez P. pacifica, le cytoplasme des spermatocytes contient de nombreux corps de Golgi, des cisternae du RER, des ribosomes, des mitochondries et des corps sphériques denses. Le matériel filamenteux est accumulé dans les spermatides qui contiennent seulement des mitochondries et un noyau fragmenté (ou lobé) dépourvu d'enveloppe nucléaire. Le sperme immature resemble aux dernières spermatides: son aire centrale filamenteuse est entourée par des particules de chromatine et quelques mitochondries. La membrane plasmatique du sperme immature forme des invaginations profondes. Les spermatozoïdes matures, dans l'utérus, sont constitués par un petit corps cellulaire principal (MCB) portant un pseudopode proéminent rempli de filaments de cytosquelette. Le MCB contient un noyau et des mitochondries. La spermatogenèse chez E. robusta (étudiées seulement au niveau des testicules) ressemble à celle décrite chez P. pacifica, mais les spermatocytes d' E. robusta sont le siège d'une activité métabolique plus faible et, par conséquent, une masse plus faible de matériel filamenteux est stockée dans les spermatides et dans le sperme immature. Les spermatozoïdes de P. pacifica et le sperme immature d' E. robusta ont les mêmes caractéristiques ultrastructurales pour des nématodes (nature amiboïde, absence d'axonème, d'acrosome et d'enveloppe nucléaire) mais aucune des organelles aberrantes particuliéres à de nombreux spermes de nématodes (organelles membraneuses, corps fibreux paracrystallins et leurs complexes) n'ont été identifiées pendant le développement du sperme chez les Chromadorides étudiés. Par cet aspect, leur spermatogenèse diffère significativement de celle des Secernentes et des Monhysterides.

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Uheda, Eiji, et Shunji Kitoh. « Electron microscopic observations of the envelopes of isolated algal packets of Azolla ». Canadian Journal of Botany 69, n^o 7 (1 juillet 1991) : 1418–19. http://dx.doi.org/10.1139/b91-183.

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The envelopes of isolated algal packets from cyanobiont-containing and cyanobiont-free Azolla were examined with the electron microscope. Both types of envelope were 10–20 nm thick and composed of three layers. The three-layer structure was also observed when algal packets were treated with cellulase, pectinase, lipase, protease, sodium hydroxide, nitric acid, or sodium dodecylsulfate. Thus, the envelopes do not appear to be membrane-like in nature and the presence and ultrastructure of the envelopes are not affected by cyanobiont filaments. Key words: algal packet, cyanobiont-free Azolla, Azolla, electron microscopic studies, envelope.

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Galeano, July A., Patrick Sandoz, Artur Zarzycki, Laurent Robert et Juan M. Jaramillo. « Microfabrication of position reference patterns onto glass microscope slides for high-accurate analysis of dynamic cellular events ». TecnoLógicas 20, n^o 39 (2 mai 2017) : 115–26. http://dx.doi.org/10.22430/22565337.695.

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Glass microscopes slides are widely used as in situ base-substrates carrying diverse micro-fabricated systems or elements. For such purposes, the micro-fabrication process consists in transferring a pre-defined design onto the substrate made of a glass microscope slide. This is known as patterning, which is a technique that can also be used in transferring specific designs that allows region of interest (ROI) recovery under the microscope. In those cases, two main challenges appear: 1) Disturbances in light transmission should remain minimum to keep the high quality of observation of the object of interest under the microscope. 2) The pattern-size should then be small enough but, however, larger than the diffraction limit to be observable satisfactorily for positioning purposes. In this article, we present the procedures involved in the microfabrication of Pseudo-Periodic Patterns (PPP) encrypting the absolute position of an extended area. Those patterns are embedded in Pétri dishes in order to allow the highaccurate retrieval of absolute position and orientation. The presented microfabrication is based in a technique known as lift-off, which after parameter adjustment, allows the obtaining of PPP fulfilling the two previously mentioned requirements. The results report on PPP realized on glass microscope slides and composed by 2µm side dots made of aluminum with a thickness of 30nm.

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Nikishin, V. P., et E. M. Skorobrechova. « Intranuclear inclusions in macrophages of lizards Lacerta agilis, experimentally infected by acanthocephalan Corynosoma strumosum ». Russian Journal of Parasitology 12, n^o 1 (27 février 2018) : 52–58. http://dx.doi.org/10.31016/1998-8435-2018-12-1-52-58.

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The purpose of the research: to study the cell response of non-natural paratenic host and encapsulation process of acanthocephalan Corynosoma strumosum in experiment for further comparison with encapsulation mechanism of this acanthocephalan in natural paratenic host. Materials and methods. Experiments were carried out on 24 lizards Lacerta agilis and one L. viridis. 17 encapsulated acanthocephalans were received from 13 of them. Acanthocephalans with capsules were prepared for electron microscopic analysis according to standard methods and examined in light (semithin sections) and under electron (in ultrathin sections) microscopes. Semithin sections were stained with methylene blue or a mixture of methylene blue and crystal violet. Ultrathin sections were stained with lead citrate. All capsules received in the experiment were investigated with the use of the light microscope; 1,5 and 10 day capsules were examined under electron microscope. Results and discussion. All acanthocephalans studied in this paper including those discovered one and half day after the start of experiment were enclosed in the thick cellular capsule with prevailing mononuclear and multinuclear macrophages. Single electron-dense inclusions of regular rounded shape surrounded by hallo of moderately dense material were found in approximately half of both types of nuclei. Nature of inclusions remained unknown. In the interpretation of results, it is necessary to take into account: 1) the presence of these inclusions in macrophage nuclei only; 2) their strictly ordinary positioning in the nucleus; 3) strictly spherical shape; 4) very high electronic density of their material, that exceeds the density of the nucleolus and chromatin; 5) presence of halo; 6) absence of visible pathological signs in nuclei and cell’s cytoplasm where these inclusions had been found. Their appearance is supposed to be connected with the overactivity of lizard macrophages caused by invasion of a parasitic worm.

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Suleman, Adam, Nigel Champion et Yuna Lee. « An Unusual Mimicker of Tumor Lysis Syndrome with Hepatic and Renal Failure ». Canadian Journal of General Internal Medicine 16, n^o 4 (20 décembre 2021) : 53–58. http://dx.doi.org/10.22374/cjgim.v16i4.518.

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A 52-year-old male presented to the emergency department with a 3-day history of malaise, nausea, and pruritic rash. He had a history of treated hepatitis C, primary immune thrombocytopenic purpura (ITP), a monoclonal gammopathy of undetermined significance (MGUS), and a remote history of intravenous heroin use. He had normal vital signs and was jaundiced with a diffuse petechial rash. His laboratory investigations revealed severe transaminitis in the thousands in a hepatocellular pattern and a platelet count of 41 × 109/L; acute kidney injury with a creatinine of 588 umol/L and potassium of 5.5 mmol/L; a uric acid of 1115 umol/L and phosphate of 2.36 mmol/L; and white blood cell casts on urine microscopy. His serum toxicology was unremarkable and urine drug screen was positive for opiates and fentanyl.He was initially managed with intravenous fluids and rasburicase given concern for severe hyperuricemia and potential tumor lysis syndrome. He had a normal computed tomographic scan of his chest and abdomen, as well as portal venous doppler. A thorough workup for hepatopathy was unrevealing, and the patient ultimately endorsed methamphetamine use 5 days prior to presentation. The presentation was ultimately felt to be consistent with methamphetamine toxicity resulting in hepatic injury, rhabdomyolysis, and potential acute interstitial nephritis, despite a negative urine drug screen result on presentation. The patient was man-aged with N-acetylcysteine for drug-induced hepatic injury shortly after admission, and his hepatic and renal function ultimately recovered after 6 weeks. RésuméUn homme de 52 ans s’est présenté à l’urgence après avoir éprouvé pendant trois jours les symptômes suivants : malaise, nausées et éruption prurigineuse. Il avait des antécédents de traitement contre l’hépatite C, de purpura thrombopénique immunologique primaire, de gammopathie monoclonale de signification indéterminée et des antécédents lointains de consommation d’héroïne par voie intraveineuse. Ses signes vitaux étaient normaux et il présentait une jaunisse accompagnée d’une éruption pétéchiale diffuse. Ses analyses de laboratoire ont révélé les éléments suivants : une transaminite grave (taux de transaminases hors de proportion) suivant un motif hépato-cellulaire et une numération plaquettaire de 41 × 109/L; une insuffisance rénale aiguë, le taux de créatinine étant de 588 µmol/L et celui de potassium étant de 5,5 mmol/L; un taux d’acide urique de 1115 µmol/L et de phosphate de 2,36 mmol/L; présence de cylindres leucocytaires à la microscopie urinaire. L’analyse toxicologique sérique était sans particularité et le dépistage de drogues dans l’urine s’est révélé positif pour les opiacés et le fentanyl. Il a d’abord été traité par l’administration intraveineuse de liquides et de rasburicase étant donné la crainte d’une hyperuricémie grave et du risque de syndrome de lyse tumorale. La tomodensitométrie du thorax et de l’abdomen était normale, de même que l’examen Doppler de la veine porte. Un examen approfondi de l’hépatopathie n’a rien révélé de concluant, et le patient a fini par avouer qu’il avait consommé de la métham-phétamine cinq jours avant l’apparition des symptômes. On a finalement estimé que le tableau clinique correspondait à une intoxication à la méthamphétamine, provoquant une atteinte hépatique, une rhabdomyolyse et une néphrite interstitielle aiguë possible, malgré un résultat négatif du test de dépistage de drogues dans l’urine lors de son arrivée. Peu après son admission, le patient a été traité par de la N-acétylcystéine pour soigner l’atteinte hépatique induite par la drogue, et ses fonctions hépatiques et rénales se sont finalement rétablies après six semaines.

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Tukiainen, Pekka, et Mark Hughes. « The cellular level mode I fracture behaviour of spruce and birch in the RT crack propagation system ». Holzforschung 70, n^o 2 (1 février 2016) : 157–65. http://dx.doi.org/10.1515/hf-2014-0297.

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Abstract The effect of the microscopic structure and the moisture content (MC) of wood on its fracture behaviour has been investigated. Green and air-dried spruce (Picea abies [L.] Karst.) and birch (Betula pendula Roth.) wood were subjected to pure mode I loading in the radial- tangential (RT) crack propagation system. Tests were carried out in situ in an environmental scanning electron microscope to observe crack propagation at the cellular level. Crack-tip displacement fields were computed by digital image correlation, and crack propagation was observed from the images captured during testing. Both the MC and the microscopic structure were found to affect the fracture process. In the air-dried birch and spruce, only microcracking caused large displacements ahead of the crack-tip. In spruce, the microcracking zone was larger than in birch. In green birch and spruce, microcracking was less evident than in the air-dried specimens, and in some cases, there were notable deformations in a few cells ahead of the crack-tip before crack extension. Microcracking is considered to be the main toughening mechanism in spruce and birch in the RT crack propagation system.

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Banavar, Spoorthi Ravi, Prashanthi Chippagiri, Rohit Pandurangappa, Saileela Annavajjula et Premalatha Bidadi Rajashekaraiah. « Image Montaging for Creating a Virtual Pathology Slide : An Innovative and Economical Tool to Obtain a Whole Slide Image ». Analytical Cellular Pathology 2016 (2016) : 1–7. http://dx.doi.org/10.1155/2016/9084909.

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Background. Microscopes are omnipresent throughout the field of biological research. With microscopes one can see in detail what is going on at the cellular level in tissues. Though it is a ubiquitous tool, the limitation is that with high magnification there is a small field of view. It is often advantageous to see an entire sample at high magnification. Over the years technological advancements in optics have helped to provide solutions to this limitation of microscopes by creating the so-called dedicated “slide scanners” which can provide a “whole slide digital image.” These scanners can provide seamless, large-field-of-view, high resolution image of entire tissue section. The only disadvantage of such complete slide imaging system is its outrageous cost, thereby hindering their practical use by most laboratories, especially in developing and low resource countries.Methods. In a quest for their substitute, we tried commonly used image editing software Adobe Photoshop along with a basic image capturing device attached to a trinocular microscope to create a digital pathology slide.Results. The seamless image created using Adobe Photoshop maintained its diagnostic quality.Conclusion. With time and effort photomicrographs obtained from a basic camera-microscope set up can be combined and merged in Adobe Photoshop to create a whole slide digital image of practically usable quality at a negligible cost.

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Cooper, M. S. « Imaging cellular dynamics using scanning laser confocal microscopy ». Proceedings, annual meeting, Electron Microscopy Society of America 50, n^o 1 (août 1992) : 12–13. http://dx.doi.org/10.1017/s0424820100120461.

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In recent years, the ability to image morphological dynamics and physiological changes in living cells and tissues has been greatly advanced by the advent of scanning laser confocal microscopy. Confocal microscopes employ optical systems in which both the condenser and objective lenses are focused onto a single volume element of the specimen. In practice, galvanometer-driven mirrors or acousto-optical deflectors are used to scan a laser beam over the specimen in a raster-like fashion through an epifluorescence microscope. The incident laser beam, as well as the collected fluorescent light, are passed through pinhole or slit apertures in image planes that are conjugate to the plane of the specimen. This method of illumination and detection prevents fluorescent light which is generated above and below the plane-of-focus from impinging on the imaging system's photodetector, thus rejecting much of the fluorescent light which normally blurs the image of a three-dimensional fluorescent specimen.

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Shotton, D. M. « Video-enhanced light microscopy and its applications in cell biology ». Journal of Cell Science 89, n^o 2 (1 février 1988) : 129–50. http://dx.doi.org/10.1242/jcs.89.2.129.

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The combination of novel optical microscopic techniques with advanced video and digital image-processing technology now permits dramatic improvements in the quality of light-microscope images. Such video-enhanced light microscopy has lead to a renaissance in the applications of the light microscope for the study of living cells in two important areas: the intensification of faint fluorescence images, permitting observation of fluorescently labelled cells under conditions of very low illuminating intensity; and the enhancement of extremely low contrast images generated by minute cellular structures, so that these may be clearly seen and their normal intracellular movements recorded. Application of both these aspects of video-enhanced light microscopy have recently led to major discoveries concerning the functioning of the living cell. In this review I discuss the equipment, procedures and image-processing principles employed in these applications, and describe and illustrate some of the spectacular results that have recently been obtained.

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Martin, Sonya, Antonio Virgilio Failla, Udo Spöri, Christoph Cremer et Ana Pombo. « Measuring the Size of Biological Nanostructures with Spatially Modulated Illumination Microscopy ». Molecular Biology of the Cell 15, n^o 5 (mai 2004) : 2449–55. http://dx.doi.org/10.1091/mbc.e04-01-0045.

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Spatially modulated illumination fluorescence microscopy can in theory measure the sizes of objects with a diameter ranging between 10 and 200 nm and has allowed accurate size measurement of subresolution fluorescent beads (∼40–100 nm). Biological structures in this size range have so far been measured by electron microscopy. Here, we have labeled sites containing the active, hyperphosphorylated form of RNA polymerase II in the nucleus of HeLa cells by using the antibody H5. The spatially modulated illumination-microscope was compared with confocal laser scanning and electron microscopes and found to be suitable for measuring the size of cellular nanostructures in a biological setting. The hyperphosphorylated form of polymerase II was found in structures with a diameter of ∼70 nm, well below the 200-nm resolution limit of standard fluorescence microscopes.

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Thiel, Cora Sandra, Svantje Tauber, Beatrice Lauber, Jennifer Polzer, Christian Seebacher, Rainer Uhl, Srujana Neelam, Ye Zhang, Howard Levine et Oliver Ullrich. « Rapid Morphological and Cytoskeletal Response to Microgravity in Human Primary Macrophages ». International Journal of Molecular Sciences 20, n^o 10 (15 mai 2019) : 2402. http://dx.doi.org/10.3390/ijms20102402.

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The FLUMIAS (Fluorescence-Microscopic Analyses System for Life-Cell-Imaging in Space) confocal laser spinning disk fluorescence microscope represents a new imaging capability for live cell imaging experiments on suborbital ballistic rocket missions. During the second pioneer mission of this microscope system on the TEXUS-54 suborbital rocket flight, we developed and performed a live imaging experiment with primary human macrophages. We simultaneously imaged four different cellular structures (nucleus, cytoplasm, lysosomes, actin cytoskeleton) by using four different live cell dyes (Nuclear Violet, Calcein, LysoBrite, SiR-actin) and laser wavelengths (405, 488, 561, and 642 nm), and investigated the cellular morphology in microgravity (10−4 to 10−5 g) over a period of about six minutes compared to 1 g controls. For live imaging of the cytoskeleton during spaceflight, we combined confocal laser microscopy with the SiR-actin probe, a fluorogenic silicon-rhodamine (SiR) conjugated jasplakinolide probe that binds to F-actin and displays minimal toxicity. We determined changes in 3D cell volume and surface, nuclear volume and in the actin cytoskeleton, which responded rapidly to the microgravity environment with a significant reduction of SiR-actin fluorescence after 4–19 s microgravity, and adapted subsequently until 126–151 s microgravity. We conclude that microgravity induces geometric cellular changes and rapid response and adaptation of the potential gravity-transducing cytoskeleton in primary human macrophages.

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Gatinois, Vincent, Boris Dmitrenko, Ahmed El Mouatani, Ségolène Debiesse, Pauline Bouret, Jacques Puechberty, Joris Vermeesch, Jean-Pierre Moles et Franck Pellestor. « Détection d’évènements cellulaires rares par microscopie à fluorescence automatisée ». Morphologie 106, n^o 354 (septembre 2022) : S11—S12. http://dx.doi.org/10.1016/j.morpho.2022.06.015.

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de Grooth, B. G., N. F. van Hulst, J. Greve, C. E. H. Berger, M. H. P. Moers et K. O. van der Werf. « Mapping viscoelasticity, (specific) adhesion and near-field fluorescence of cellular structures with scanning probe microscopy ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 720–21. http://dx.doi.org/10.1017/s0424820100139974.

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One of the major features of scanning probe microscopy is the ability to produce high-resolution images in air and in liquid. This makes these microscopes potentially very useful for the study of biological materials. Indeed the number of reports that use these microscopes, especially the atomic force microscope (AFM), has increased exponentially in the past decade. However, in order to become a routine apparatus that is able to image live processes at a scale of a few nanometers, the instrumentation of the AFM has to be improved. First of all, under normal operation, the movement of the tip across the surface of fragile biological structures such as cell membranes, often results in movement or even destruction of the object. Secondly, the lack of specificity of the AFM makes it difficult to identify the observed structures. Other problems include the low imaging speed and problems associated with the tip-sample convolution. Here we will report on attempts to improve the first two points: sample destruction and specificity.It has become clear recently that for operation in air the so-called tapping mode AFM is much more gentle for the sample than the standard operation mode.

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Rosenfeld, M. E., C. Karboski, M. F. Prescott, P. Goodwin et R. Ross. « Morphometric analysis of cellular interactions with the endothelium during the development of arterial lesions using Scanning Electron Microscopy and digital image analysis ». Proceedings, annual meeting, Electron Microscopy Society of America 45 (août 1987) : 918–19. http://dx.doi.org/10.1017/s0424820100128870.

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Previous research documenting the chronology of the cellular interactions that occur on or below the surface of the endothelium during the initiation and progression of arterial lesions, primarily consisted of descriptive studies. The recent development of lower cost image analysis hardware and software has facilitated the collection of high resolution quantitative data from microscopic images. In this report we present preliminary quantitative data on the sequence of cellular interactions that occur on the endothelium during the initiation of atherosclerosis or vasculitis utilizing digital analysis of images obtained directly from the scanning electron microscope. Segments of both atherosclerotic and normal arteries were obtained from either diet-induced or endogenously (WHHL) hypercholesterolemic rabbits following 1-4 months duration of hypercholesterolemia and age matched control rabbits. Vasculitis was induced in rats following placement of an endotoxin soaked thread adjacent to the adventitial surface of arteries.

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Weimar, Jörg R. « Coupling microscopic and macroscopic cellular automata ». Parallel Computing 27, n^o 5 (avril 2001) : 601–11. http://dx.doi.org/10.1016/s0167-8191(00)00080-6.

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Izeddin, Ignacio, Xavier Darzacq et Maxime Dahan. « Microscopies cellulaires à l’échelle de la molécule individuelle ». médecine/sciences 27, n^o 5 (mai 2011) : 547–52. http://dx.doi.org/10.1051/medsci/2011275022.

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Piston, David W. « Two-Photon Excitation Microscopy in Cellular Biophysics ». Proceedings, annual meeting, Electron Microscopy Society of America 54 (11 août 1996) : 276–77. http://dx.doi.org/10.1017/s0424820100163848.

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Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10 5 limits the average input power to less than 10 mW, only slightly greater than the power normally used in confocal microscopy.Three properties TPEM give this method a tremendous advantage over conventional optical sectioning microscopies for the study of thick samples: 1) The excitation is limited to the focal volume because of the intensity-squared dependence of the two-photon absorption. This inherent localization provides three-dimensional resolution and eliminates background equivalent to an ideal confocal microscope without requiring a confocal spatial filter, whose absence enhances fluorescence collection efficiency. Confinement of excitation to the focal volume also minimizes photobleaching and photo damage - the ultimate limiting factors in fluorescence microscopy of living cells and tissues. 2) The two-photon technique allows imaging of UV fluorophores with conventional visible light optics in both the scanning and imaging systems, because both the red excitation light (~700 nm) and the blue fluorescence (>400 nm) are within the visible spectrum. 3) Red or infrared light is far less damaging to most living cells and tissues than bluer light because fewer biological molecules absorb at the higher wavelengths. Longer wavelength excitation also reduces scattering of the incident light by the specimen, thus allowing more of the input power to reach the focal plane. This relative transparency of biological specimens to 700 nm light permits deeper sectioning, since both absorbance and scattering are reduced.

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Al-Bagdadi, F., B. Singh et R. B. Arlinghaus. « Ultrastructural morphology of cells transformed with temperature-sensitive mutant of Mo-MuSV ». Proceedings, annual meeting, Electron Microscopy Society of America 47 (6 août 1989) : 1076–77. http://dx.doi.org/10.1017/s042482010015736x.

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It is known that one of the abnormal behavior of cancer cells is changes in morphology. There is very little information in the literature on the morphological aspects of cell lines at the electron microscopic level transformed by viral mos gene (Culp, 1971; Hynes et al., 1978; Brown et al., 1981; Arlinghaus, 1985; Terasaki et al., 1986). NRK-6m2 is a cell line infected with a temperature sensitive mutant (tsll0) of Moloney murine sarcoma virus (Arlinghaus, 1985). The attempt in this study is to examine the ultrastructure of NRK-6m2 cells and relate the morphological changes to gag-mos induced cellular transformation.NRK-6m2 cell cultures were maintained in McCoy's 5a medium supplemented with 15% fetal calf serum. Subconfuluent cells were washed twice in cold phosphate buffered saline and fixed in situ in 1% glutaraldehyde, scraped and centrifuged at 1500 g for 5 min at 4°C, post fixed in osmium tetroxided and processed for electron microscopic study. Silver sections were stained with uranyl acetate and lead citrate and examined on a Joel 1200 EX electron microscope.

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Periasamy, Ammasi, Xue F. Wang, Pawel Wodnick, Gerald W. Gordon, Seongwook Kwon, Pamela A. Diliberto et Brian Herman. « High-Speed Fluorescence Microscopy : Lifetime Imaging in the Biomedical Sciences ». Microscopy and Microanalysis 1, n^o 1 (février 1995) : 13–23. http://dx.doi.org/10.1017/s1431927695110132.

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The ability to observe the behavior of living cells and tissues provides unparalleled access to information regarding the organization and dynamics of complex cellular structures. While great strides have been made over the past 30 to 40 years in the design and application of a variety of novel optical microscopic techniques, until recently, it has not been possible to image biological phenomena that occur over very short time periods (nanosecond to millisecond) or over short distances (10 to 1000 Å). However, the recent combination of (1) very rapidly gated and sensitive image intensifiers and (2) the ability to deliver fluorescence excitation energy to intact living biological specimens in a pulsed or sinusoidally modulated fashion has allowed such measurements to become a reality through the imaging of the lifetimes of fluorescent molecules. This capability has resulted in the ability to observe the dynamic organization and interaction of cellular components on a spatial and temporal scale previously not possible using other microscopic techniques. This paper discusses the implementation of a fluorescence lifetime imaging microscope (FLIM) and provides a review of some of the applications of such an instrument. These include measurements of receptor topography and subunit interactions using fluorescence resonance energy transfer (FRET), fluorescence anisotropy of phospholipids in cell membranes, cytosolic free calcium (Ca2+)i and the detection of human papillomavirus (HPV) infection in clinical cervicovaginal smears.

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Anyanwu, Godson Emeka, Augustine Uchechukwu Agu et Ugochukwu Bond Anyaehie. « Enhancing learning objectives by use of simple virtual microscopic slides in cellular physiology and histology : impact and attitudes ». Advances in Physiology Education 36, n^o 2 (juin 2012) : 158–63. http://dx.doi.org/10.1152/advan.00008.2012.

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The impact and perception of students on the use of a simple, low technology-driven version of a virtual microscope in teaching and assessments in cellular physiology and histology were studied. Its impact on the time and resources of the faculty were also assessed. Simple virtual slides and conventional microscopes were used to conduct the same examinations for the same students. Students performed significantly better in the examination with the virtual slide and also showed a significantly higher preference for virtual slides. The time and cost implications of conducting examinations using the simple virtual slides were reduced by >1,400%. The results reemphasize the need for the design and adoption of simple sustainable technological innovations in developing countries to bridge gaps in purposeful learning environments.

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Zavodszky, Gábor, Britt van Rooij, Victor Azizi, Saad Alowayyed et Alfons Hoekstra. « Hemocell : a high-performance microscopic cellular library ». Procedia Computer Science 108 (2017) : 159–65. http://dx.doi.org/10.1016/j.procs.2017.05.084.

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