Single glucose biofuel cells implanted in rats power electronic devices.

We describe the first implanted glucose biofuel cell (GBFC) that is capable of generating sufficient power from a mammal's body fluids to act as the sole power source for electronic devices. This GBFC is based on carbon nanotube/enzyme electrodes, which utilize glucose oxidase for glucose oxidation and laccase for dioxygen reduction. The GBFC, implanted in the abdominal cavity of a rat, produces an average open-circuit voltage of 0.57 V. This implanted GBFC delivered a power output of 38.7 µW, which corresponded to a power density of 193.5 µW cm(-2) and a volumetric power of 161 µW mL(-1). We demonstrate that one single implanted enzymatic GBFC can power a light-emitting diode (LED), or a digital thermometer. In addition, no signs of rejection or inflammation were observed after 110 days implantation in the rat.

Impact of AQP3 inducer treatment on cultured human keratinocytes, ex vivo human skin and volunteers.

One of the main functions of the skin is to protect the organism against environmental threats, such as thermal stress. Aquaporin-3 (AQP3) facilitates water and glycerol transport across cell membranes and therefore regulates osmotic balance in different situations of stress. This mechanism seems to be particularly important for the resistance of different organisms to cold stress. Consequently, we were interested in investigating the effect of cold and osmotic stress on AQP3 expression in normal human keratinocytes. We developed a new active ingredient to stimulate aquaporins in skin and demonstrated the partial restoration of AQP3 expression in keratinocytes transfected with AQP3 siRNA. Moreover, we examined the effect of cold stress on cell morphology and the impact of a pre-treatment with the active ingredient. Our results indicated that induction of AQP3 helped maintain a correct organization of the actin cytoskeleton, preserving cell morphology and preventing cells from rounding. Immunofluorescent staining revealed cytoplasmic localization of AQP3 and its translocation to the cell membrane following osmotic stress. Histological ex vivo studies of skin under different conditions, such as cold environment and tape-stripping, indicated that increase in AQP3 expression appears to be involved in skin protection and showed that the pattern of AQP3 expression was more enhanced in the active ingredient-treated samples. In vivo confocal microscopy by Vivascope showed a generally healthier appearance of the skin in the treated areas. These results attest to the potential value of the active ingredient in optimizing environmental stress resistance and protecting the skin from stratum corneum damage.

Maintenance of the ubiquitin-proteasome system activity correlates with visible skin benefits.

Researches on longevity and anti-ageing molecules have clearly evidenced the potential to increase lifespan of the cells. These recent scientific data raise interests and questions on the capacity of the cells to live longer and maintain their fundamental mechanisms of protection, reparation or degradation of abnormal proteins to maintain their capital of healthy and functional cellular activity. In this concern, this study was focused on the ubiquitin-proteasome system as an essential cellular tool to maintain the pool of functionally active proteins allowing renewal of proteins and degradation of damaged proteins. As the proteasome keeps the 'cells health capital', it should be particularly interesting to associate the maintenance of the proteasome activity with increasing longevity. Indeed, although oxidative stress damage increases with ageing leading to collagen and cellular membrane alterations, it also leads to a reduction in the proteasome activity which is critical for the cells. The aim of this study was to better understand the cellular role of the proteasome and to provide new data showing the skin beneficial effects in activating the overall system of ubiquitination and proteasomal degradation. For this purpose, in vitro, ex vivo and in vivo experiments were performed to evaluate the effects of maintaining the ubiquitin-proteasome activity in basal and stress conditions on young versus aged cells. Experiments have included evaluation of a newly developed dimerized tripeptide targeting specifically the ubiquitin-proteasome pathway. Our results have demonstrated that maintenance of this essential mechanism that participates in abnormal protein elimination and protein renewal allows maintaining cellular integrity that correlates with visible skin benefits.

Image analysis to quantify histological and immunofluorescent staining of ex vivo skin and skin cell cultures.

Image processing steps and analysis techniques were developed for the quantification of photomicrographs obtained from light and fluorescence microscopy. The substrates examined were either skin cell cultures, such as normal human keratinocytes (NHK) or fibroblasts, or ex vivo skin sections. Examples of the analyses are provided for the comparison of skincare active ingredient treated samples vs. placebo to demonstrate the utility of the methods to quantify and provide numerical data for a procedure that is typically qualitative in nature and based on observations by a histologist. Quantifiable experiments that are discussed include: Fontana Masson staining for melanin expression; Nile red staining to detect cellular lipid droplets; nuclei staining with diamidino-phenylindole (DAPI); and immunofluorescent staining of protein expression with a primary antibody directed against the protein (antigen) and a secondary antibody tagged with a fluorescent dye (Alexa Fluor 488) against the primary antibody.

Noise of surface bio-potential electrodes based on NASICON ceramic and Ag-AgCl.

The electrochemical noise from dry NASICON-based surface electrodes and pregelled Ag-AgCl electrodes is evaluated in saline solutions and on the skin. The electrochemical noise from the electrode/electrolyte interface is found to be negligible (less than 1 microV peak to peak). On the skin, the noise level is highly dependent on the patient. At high frequencies, the skin/electrode interface noise is equal to 'thermal noise' and can be related to the real part of the skin/electrode impedance. At low frequencies (F < 100 Hz), excess noise is observed that varies as f-2. It is tentatively ascribed to a non-stationary process or noise of electrochemical origin due to the ionic nature of the skin. The contribution of residual EMG signal of low amplitude (5 microV peak to peak) is suggested for electrodes with large surface area.

Non-polarisable dry electrode based on NASICON ceramic.

A NASICON-type ceramic (high sodium ion conductor) is proposed to record bioelectric signals. The electrode does not need gel before its application. The principle of the measurements is based on a sodium ion exchange between the skin and the material. Electrical measurements performed in saline solutions show that the electrode is slightly polarisable. The skin-electrode impedance was investigated. The impedance decreases as a function of the time of application. The resistive component is the major source of the impedance change. This can be explained by the perspiration process which occurs immediately with time after the application of the NASICON-based electrode on the skin. The skin condition is also an important parameter. NaCl saline solution or abrasion causes the resistance to decrease markedly.