Morphological and molecular characterization of actinic lentigos reveals alterations of the dermal extracellular matrix.

BACKGROUND: Actinic lentigos (AL) are benign hyperpigmented skin lesions associated with photoageing. Despite their high prevalence, biological mechanisms driving their formation remain unclear. OBJECTIVES: To provide new insights about the physiopathology of AL through a comprehensive description of their histological and molecular features. METHODS: Quantitative analysis of dermoscopic images was used to select AL containing elongated patterns, predicted to display a highly deformed dermal-epidermal junction (DEJ), on the back of the hands of 15 Caucasian women. Biopsies from lesional and adjacent nonlesional (NL) areas were processed for histological analysis or gene expression profiling. RESULTS: Histological staining confirmed a drastic deformation of the DEJ in AL, with deep epidermal invaginations into the dermis. Although the melanin content was significantly higher in AL compared with NL epidermis, the distribution of melanocytes along the DEJ was unchanged. Transcriptomic analysis revealed a signature of 529 genes differently expressed in AL vs. NL skin. Alteration of epidermal homeostasis was confirmed by the dysregulation of keratinocyte proliferation and differentiation markers. Surprisingly, canonical genes involved in melanogenesis were not significantly modulated in AL. A striking finding was the overexpression of a large group of genes involved in dermal extracellular matrix organization and remodelling. Dermal alterations were confirmed by immunolabellings on AL and NL sections. CONCLUSIONS: Drastic disorganization of the cutaneous structure in AL is accompanied by a specific molecular signature revealing alterations in both epidermal and dermal compartments. In particular, our results suggest that local modifications of the dermal extracellular matrix might contribute to hyperpigmentation in AL.

High-throughput monitoring of major cell functions by means of lensfree video microscopy.

Quantification of basic cell functions is a preliminary step to understand complex cellular mechanisms, for e.g., to test compatibility of biomaterials, to assess the effectiveness of drugs and siRNAs, and to control cell behavior. However, commonly used quantification methods are label-dependent, and end-point assays. As an alternative, using our lensfree video microscopy platform to perform high-throughput real-time monitoring of cell culture, we introduce specifically devised metrics that are capable of non-invasive quantification of cell functions such as cell-substrate adhesion, cell spreading, cell division, cell division orientation and cell death. Unlike existing methods, our platform and associated metrics embrace entire population of thousands of cells whilst monitoring the fate of every single cell within the population. This results in a high content description of cell functions that typically contains 25,000 - 900,000 measurements per experiment depending on cell density and period of observation. As proof of concept, we monitored cell-substrate adhesion and spreading kinetics of human Mesenchymal Stem Cells (hMSCs) and primary human fibroblasts, we determined the cell division orientation of hMSCs, and we observed the effect of transfection of siCellDeath (siRNA known to induce cell death) on hMSCs and human Osteo Sarcoma (U2OS) Cells.

Confocal bi-protocol: a new strategy for isotropic 3D live cell imaging.

The conventional approach for microscopic 3D cellular imaging is based on axial through-stack image series which has some significant limitations such as anisotropic resolution and axial aberration. To overcome these drawbacks, we have recently introduced an alternative approach based on micro-rotation image series. Unfortunately, this new technique suffers from a huge burden of computation that makes its use quite difficult for current applications. To address these problems we propose a new imaging strategy called bi-protocol, which consists of coupling micro-rotation acquisition and conventional z-stack acquisition. We experimentally prove bi-protocol 3D reconstruction produces similar quality to that of pure micro-rotation, but offers the advantage of reduced computation burden because it uses the z-stack volume to accelerate the registration of the micro-rotation images.

Isotropic high-resolution three-dimensional confocal micro-rotation imaging for non-adherent living cells.

Recently, micro-rotation confocal microscopy has enabled the acquisition of a sequence of micro-rotated images of nonadherent living cells obtained during a partially controlled rotation movement of the cell through the focal plane. Although we are now able to estimate the three-dimensional position of every optical section with respect to the cell frame, the reconstruction of the cell from the positioned micro-rotated images remains a last task that this paper addresses. This is not strictly an interpolation problem since a micro-rotated image is a convoluted two-dimensional map of a three-dimensional reality. It is rather a 'reconstruction from projection' problem where the term projection is associated to the PSF of the deconvolution process. Micro-rotation microscopy has a specific difficulty. It does not yield a complete coverage of the volume. In this paper, experiments illustrate the ability of the classical EM algorithm to deconvolve efficiently cell volume despite of the incomplete coverage. This cell reconstruction method is compared to a kernel-based method of interpolation, which does not take account explicitly the point-spread-function (PSF). It is also compared to the standard volume obtained from a conventional z-stack. Our results suggest that deconvolution of micro-rotation image series opens some exciting new avenues for further analysis, ultimately laying the way towards establishing an enhanced resolution 3D light microscopy.

Contextual performance prediction for low-level image analysis algorithms.

This paper explores a generic approach to predict the output accuracy of an algorithm without running it, by a careful examination of the local context. Such a performance prediction will allow one to qualify the appropriateness of an algorithm to treat images with given properties (contrast, resolution, noise, richness in details, contours or textures, etc.) resulting either from experimental acquisition conditions or from a specific type of scene. We have to answer the following question: a context c being given at any site, what will be the performance? In our experiments, c is described by three contextual variables: Gabor components, entropy and signal noise ratio. As initially proposed in the related work, the prediction function is determined from training using a logistic regression model. This technique is illustrated on aerial infrared images for two types of algorithm: edge detection and displacement estimation.

[Comparison between hypo- and hyperglucidic diets on protein sparing in major visceral surgery (author's transl)]. / Comparaison de deux régimes hypo- et hyperglucidiques sur l'épargne azotée post-opératoire en chirurgie viscérale majeure. Répercussions sur l'aminogramme plasmatique et urinaire.

The authors compare the protein sparing effect of two diets, exclusively intravenous, including the same protein intake, but a different caloric intake, 21 calories/gm nitrogen for diet "A" (20 cases); 138 calories/gm nitrogen for diet "B" (20 cases). This has been observed during the six post-operative days of major visceral surgery: oesophagectomy, total gastrectomy, colic or rectocolic exeresis, sequestrectomy for acute pancreatitis, lots having been drawn for the diets. Daily nitrogen balances have been made and plasmatic and urinary levels of amino-acids have been measured before surgery and on the third and fifth post-operative days. Statistical exploitation is done by variance analysis (linear model of three factors) with a 99% confidence ratio: 1) Patient factor has no influence whatsoever on cumulative nitrogen balance. 2) Time factor arises only on the fourth post-operative day and only in the hypocaloric diet, leading to catabolism. 3) Metabolic condition is determinant. On no cancerous disease, superiority of hypercaloric diet is well demonstrated. On cancerous disease, nitrogen loss is only significantly different on 4th and 5th post-operative day: hypercaloric diet gives a better nitrogen balance.