Changes in Tactile Spatial Discrimination and Cutaneous Coding Properties by Skin Hydration in the Elderly

SummaryNeurosensory tactile functions were investigated in human subjects by two different and complementary experimental approaches. First, a conventional psychophysical method (two-point gap discrimination) was used to determine the tactile discrimination threshold by analyzing the subjects' ability to detect a gap of variable width between two contact points when a series of stimuli was applied to the skin. Using this method we confirmed the marked degradation of tactile spatial acuity with age and showed that skin discriminative function was partially restored after hydration of the skin with a moisturizer. The second approach consisted of a microneurographic recording of tactile afferent fibers in response to two types of mechanical stimuli applied reproducibly to the corresponding receptive fields. With this method, we found that the afferent messages were depressed following hydration of the skin surface. Thus, partial restoration of tactile spatial acuity after hydration appears to be due to both a softening of the stratum corneum permitting better localization of the stimulus and a weaker transfer of the stimulus toward the sensory receptors

Assessment of Aging of the Human Skin by In Vivo Ultrasonic Imaging

The ultrasonic imaging technique that we have developed provides cross-sectional images of human skin in vivo with a resolution of about 80 μm axially (i.e., deep into the skin) and 250 μm lateral (parallel to the surface). In order to study aging skin, we obtained ultrasonic images from the mid-fore-arm (volar and dorsal sides) of 142 women. Ultrasonically, on the images, the dermis appears composed of two bands: a dark superficial one where the ultrasonic waves are propagated in a relatively homogeneous or non-echogenic medium, and a deeper one, which is lighter in color, suggesting a heterogeneous medium. Our results show that skin is thicker on the dorsal than on the volar forearm. In contrast to previously published results, skin thickness remains constant until the seventh decade of life, diminishing thereafter. The relative thicknesses of the two bands show marked variations with age: a progressive thickening of the dark band, from zero in infants to approximately 75% of total skin thickness in aged subjects, while the light band shows the inverse trend. Comparing the amplitude of the bands on the volar and dorsal forearm, the relative thickness of the dark band is larger on the dorsal (exposed) side and increases with age. These findings and the analysis of variously stained biopsies taken in some of our patients lead us to assign this dark band to a zone in the upper dermis where the collagen network is delicate, dense, and well organized. This is supported by some data in the literature. The thickness of this subepidermal non-echogenic band appears to be a far more sensitive marker of skin aging at the dermal level than is the measurement of skin thickness

Front Microbiol

Since 2021, 3 variants of concern (VOC) have spread to France, causing successive epidemic waves. To describe the features of Alpha, Delta and Omicron VOC circulation in the Nouvelle-Aquitaine region, France, between February 2021 and February 2022. Data from the three university hospitals (UH) of Nouvelle-Aquitaine were used to describe regional SARS-CoV-2 circulation (RT-PCR positive rates and identified VOC) as well as its consequences (total number of hospitalizations and admissions in intensive care unit). They were analyzed according to the predominant variant and compared with national data. A total of 611,106 SARS-CoV-2 RT-PCR tests were performed in the 3 Nouvelle-Aquitaine UH during the study period. The 37,750 positive samples were analyzed by variant-specific RT-PCR or whole-genome sequencing. In 2021, Alpha VOC was detected from week 5 until week 35. Delta became the most prevalent variant (77.3%) in week 26, reaching 100% in week 35. It was replaced by Omicron, which was initially detected week 48, represented 77% of positive samples in week 52 and was still predominant in February 2022. The RT-PCR positive rates were 4.3, 4.2, and 21.9% during the Alpha, Delta and Omicron waves, respectively. The ratio between intensive care unit admissions and total hospitalizations was lower during the Omicron wave than during the two previous waves due to the Alpha and Delta variants. This study highlighted the need for strong regional cooperation to achieve effective SARS-CoV-2 epidemiological surveillance, in close association with the public health authorities

Longitudinal study of skin aging: from microrelief to wrinkles.

International audienceAIM: To study the changes in skin microrelief and periocular wrinkles during the aging process. METHODS: Replicas of the crow's feet area of volunteers were recorded in 1987 and 2008 and observed comparatively. Characteristic features were quantified by image analysis. RESULTS: Observation shows that some microrelief features disappear and even merge with wrinkles that become more marked. Some primary lines also tend to merge to form thin new wrinkles. Quantitative data support these observations: the size of small and medium objects of skin relief decreases with age while large objects are becoming larger. CONCLUSION: Over 21 years, in the group studied, the total area of the detected objects remains quite constant. Only the distribution between small and large detected objects (microrelief features and wrinkles, respectively) is modified

Influence of Stratum Corneum on the entire skin mechanical properties, as predicted by a computational skin model.

International audienceBACKGROUND/PURPOSE: Skin mechanical properties are globally well described. The aim of this paper is to evaluate, by means of a numerical model, the influence of Stratum Corneum (SC) on skin folding resulting from an in-plane compression. METHODS: A computational skin model was developed where skin is divided into three layers (SC, epidermis and upper dermis, and deep dermis) of different thicknesses and elastic moduli. Skin surface deformation, consecutive to the application of a given surface compression, was computed by minimizing the mechanical energy of the multi-layered tissue. Influence of SC thickness and elastic modulus on skin buckling is presented. RESULTS: Varying both SC thickness and elastic modulus has a marked influence on both wavelength and amplitude of the skin's surface folds. These two parameters display a logarithmic variation versus SC elastic modulus. CONCLUSION: Although representing about one hundredth of the total skin thickness, SC has a marked influence on the skin mechanical properties

EEMCO guidance for the measurement of skin microcirculation.

peer reviewedThe blood supply to the skin is provided by a network of arterioles, capillaries and venules organized into a superficial and a deep plexus. The assessment of skin microcirculation is of valuable interest in cosmetology in the quantification of the sun protection factor, skin irritation and efficacy of antiredness treatments. Skin microcirculation can be measured by means of different techniques, based mainly on the quantification of optical and thermal properties of the skin which are modified by the amount of blood perfusion. Relevant and reproducible data can be obtained only through the understanding of the biophysical background of the technique(s) utilized. Standardization of measuring conditions and procedures is particularly required for blood flow assessment. In this paper, the advantages and disadvantages of the main techniques in use are discussed, and optimization of measurements for laser Doppler techniques is described

Les formulations cosmétiques à base de plomb

International audienc

Cadastres et voie Domitienne. Structures et articulations morpho-historiques

Chouquer Gérard, Clavel-Lévêque Monique, Dodinet Marianne, Favory François, Fiches Jean-Luc. Cadastres et voie Domitienne. Structures et articulations morpho-historiques. In: Dialogues d'histoire ancienne, vol. 9, 1983. pp. 87-111

Conservation des signatures isotopiques du collagène d'os et de dents du pleistocene supérieur (Saint-Césaire, France) : implications pour les reconstitutions des régimes alimentaires des néandertaliens

Preservation of isotopic signals in upper pleistocene bone and tooth collagen (Saint-Césaire, France) : Implications for dietary reconstructions of neanderthals. Abstract. — Analysis of the carbon and nitrogen isotopic composition of bone and tooth collagen is a reliable way to investigate the dietary adaptations of past human populations. The Upper Pleistocene site of Saint-Césaire (40,000-30,000 years BP, Charente-Maritime, France) provides a good context for the isotopic study of a Neanderthal skeleton. Faunal samples associated with the human fossil exhibit different states of preservation in different stratigraphie positions. Diagenetic processes did not significantly alter the isotopic composition of collagen of the best-preserved samples. Before attempting isotopic analysis of the Neanderthal remains from Saint-Césaire, organic matter preservation will have to be estimated first, and it may be necessary to modify the extraction protocol in order to sample a minimal amount of materials.Résumé. — L'analyse isotopique du carbone et de l'azote du collagène des tissus minéralisés est une méthode d'investigation éprouvée des comportements alimentaires des populations humaines du passé. Le site pleistocene de Saint-Césaire (40000-30000 ans BP, Charente-Maritime, France) offre un cadre propice à l'étude isotopique d'un squelette de Néandertalien. Les échantillons osseux et dentaires de la faune associée aux restes humains de ce site présentent une préservation différentielle de la matière organique selon la position stratigraphique des fossiles. Les processus de diagenèse n'ont pas significativement modifié les signatures isotopiques des collagènes extraits des échantillons les mieux conservés. L'application de l'analyse isotopique aux ossements néandertaliens de Saint-Césaire devra être précédée d'une évaluation de leur état de conservation, et nécessitera peut-être des modifications du protocole d'extraction du collagène de façon à prélever une quantité minimale de matériel.Drucker Dorothée, Bocherens Hervé, Mariotti André, Lévêque François, Vandermeersch Bernard, Guadelli Jean-Luc. Conservation des signatures isotopiques du collagène d'os et de dents du pleistocene supérieur (Saint-Césaire, France) : implications pour les reconstitutions des régimes alimentaires des néandertaliens. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, Nouvelle Série. Tome 11 fascicule 3-4, 1999. pp. 289-305