Characterization Of Human Skin Through Photoacoustic Spectroscopy

The photoacoustic technique is based on the absorption of modulated light by a sample and subsequent heat generation. This generates thermal waves that propagate in the surrounding media According to the Rosencwaig-Gersho Model, such waves produce the pressure oscillation detected as the photoacoustic signal. This technique allows the spectroscopic characterization of multilayer systems: as the thermal diffusion length varies with the modulation frequency of the absorbed light, the depth profile of a sample can be studied by the analysis of the photoacoustic signal at different modulation frequencies. In this work, photoacoustic spectroscopy was used to characterize different human skin samples. Measurements were performed at 70Hz and 17Hz, using a 1000W Xe arc lamp as the light source, for wavelengths between 240nm and 700nm. Skin samples were about 0,5cm diameter. It was possible to obtain the photoacoustic absorption spectra of the stratum corneum and of a deeper layer of epidermis; when the lower modulation frequency is utilized, photoacoustic spectroscopy characterizes the absorption of the whole epidermis, because in this case the thermal diffusion length is thicker than that of the stratum corneum. Photoacoustic spectroscopy was also employed to monitor the drying kinetics of the skin. This was done by analyzing the time evolution of the photoacoustic spectra of skin samples. Pre-treatment of the samples included different periods in a drying chamber. Measurements show that the photoacoustic spectra changes according to the humidity of the skin. Future work includes detailed monitoring of skin hydration.5325136142Morganti, P., Ruocco, E., Wolf, R., Ruocco, V., Percutaneous absorption and delivery systems (2001) Clinics in Dermatology, 19, pp. 489-501Junqueira, L.C., Carneiro, J., (1995) Histologia Básica, 8a Ed., pp. 301-303Bernengo, J.C., Gasquez, C., Falson-Rieg, F., Photoacoustics as a tool for cutaneous permeation studies (1998) High Temperatures-High Pressures, 30, pp. 619-624Gutiérrez-Juárez, G., Vargas-Luna, M., Córdova, T., Varela, J.B., Bernal-Alvarado, J.J., Sosa, M., In vivo measurement of the human skin absorption of toppically applied substances by photoacoustic technique (2002) Physiological Measurement, 23, pp. 1-12Puccetti, G., Lahjomri, F., Leblanc, R.M., Pulsed photoacoustic spectroscopy applied to the diffusion of sunscreen chromophores in human skin: The weakly absorbent regime (1997) Journal of Photochemistry and Photobiology B: Biology, 39, pp. 110-120Vinha, C.A., Haas, U., Qualitative and semiquantitative analysis of dried fruits and seasoning products of paprika using photoacoustic spectroscopy (1997) Journal of Agricultural and Food Chemistry, 45 (4), p. 127

Sunscreen Effects In Skin Analyzed By Photoacoustic Spectroscopy

In the photoacoustic technique, the signal is proportional to the heat produced in a sample as a consequence of modulated light absorption. This technique allows the spectroscopic characterization of multilayer systems: as the thermal diffusion length varies with the light modulation frequency, one can obtain the depth profile of the sample by analyzing the frequency-dependence of the signal. As the photoacoustic signal depends on thermal and optical properties of the sample, structural changes in the system under analysis account for signal variations in time. In this work, photoacoustic spectroscopy was used to characterize samples of sunscreen and the system formed by sunscreen plus skin. Measurements used a 1000W Xe arc lamp as light source, for wavelengths between 240nm and 400nm. This range corresponds to most of the UV radiation that reaches Earth. Skin samples were disks of about 0,5cm diameter. The absorption spectrum of sunscreen was obtained. Finally, photoacoustics was employed to monitor the absorption kinetics of the sunscreen applied to skin samples. This was done by applying sunscreen in a skin sample and recording the photoacoustic spectra in regular time intervals, up to 90 minutes after application. According to measurements, light absorption by the sunscreen plus skin system stabilizes between 25 and 45 minutes after sunscreen application. Results show that this technique can be utilized to monitor drug delivery and farmacokinetics in skin samples.5325143149Barja, P.R., (1996) Estudo da Indução Fotossintética Através da Técnica Fotoacústica: Efeitos de Saturação e Fotoinibição, , (master thesis), IFGW, UNICAMPRosencwaig, A., (1980) Photoacoustics and Photoacoustic Spectroscopy, pp. 219-231. , New York, John Wiley & SonsPucceti, G., Leblanc, R.M., A comparative study on chromophore diffusion inside porous filters by pulsed photoacoustic spectroscopy (1996) Journal of Membrane Science, 119, pp. 213-228Gutiérrez-Juárez, G., Vargas-Luna, M., Córdova, T., In vivo measurement of the human skin absorption of topically applied substances by photoacoustic technique (2002) Physiological Measurement, 23, pp. 1-12Bernengo, J.C., Photoacoustics as a tool for cutaneous permeation studies (1998) High Temperatures-high Pressures, 30, pp. 619-624Azevedo, J.S., UVA/UVB sunscreen determination by second-order derivative ultraviolet spectrophotometry (1999) II Farmaco, 54, pp. 573-578Rettberg, P., Horneck, G., Biologically weighted measurement of UV radiation in space on Earth with the biofilm technique (2000) Advanced Space Research, 26, pp. 2005-2014Van Der Leun, J.C., UV radiation from sunlight: Summary, conclusions and recommendations (1996) Journal of Photochemistry and Photobiology B: Biology, 35, pp. 237-2441Wolf, R., Sunscreens (2001) Clinics in Dermatology, 19, pp. 452-45

Thy-1 (CD90)-Induced Metastatic Cancer Cell Migration and Invasion Are β3 Integrin-Dependent and Involve a Ca²⁺/P2X7 Receptor Signaling Axis.

Cancer cell adhesion to the vascular endothelium is an important step in tumor metastasis. Thy-1 (CD90), a cell adhesion molecule expressed in activated endothelial cells, has been implicated in melanoma metastasis by binding to integrins present in cancer cells. However, the signaling pathway(s) triggered by this Thy-1-Integrin interaction in cancer cells remains to be defined. Our previously reported data indicate that Ca <sup>2+</sup> -dependent hemichannel opening, as well as the P2X7 receptor, are key players in Thy-1-α <sub>V</sub> β <sub>3</sub> Integrin-induced migration of reactive astrocytes. Thus, we investigated whether this signaling pathway is activated in MDA-MB-231 breast cancer cells and in B16F10 melanoma cells when stimulated with Thy-1. In both cancer cell types, Thy-1 induced a rapid increase in intracellular Ca <sup>2+</sup> , ATP release, as well as cell migration and invasion. Connexin and Pannexin inhibitors decreased cell migration, implicating a requirement for hemichannel opening in Thy-1-induced cell migration. In addition, cell migration and invasion were precluded when the P2X7 receptor was pharmacologically blocked. Moreover, the ability of breast cancer and melanoma cells to transmigrate through an activated endothelial monolayer was significantly decreased when the β <sub>3</sub> Integrin was silenced in these cancer cells. Importantly, melanoma cells with silenced β <sub>3</sub> Integrin were unable to metastasize to the lung in a preclinical mouse model. Thus, our results suggest that the Ca <sup>2+</sup> /hemichannel/ATP/P2X7 receptor-signaling axis triggered by the Thy-1-α <sub>V</sub> β <sub>3</sub> Integrin interaction is important for cancer cell migration, invasion and transvasation. These findings open up the possibility of therapeutically targeting the Thy-1-Integrin signaling pathway to prevent metastasis

Protein kinase B (AKT) upregulation and Thy-1-α_vβ₃ integrin-induced phosphorylation of Connexin43 by activated AKT in astrogliosis.

In response to brain injury or inflammation, astrocytes undergo hypertrophy, proliferate, and migrate to the damaged zone. These changes, collectively known as "astrogliosis", initially protect the brain; however, astrogliosis can also cause neuronal dysfunction. Additionally, these astrocytes undergo intracellular changes involving alterations in the expression and localization of many proteins, including α <sub>v</sub> β <sub>3</sub> integrin. Our previous reports indicate that Thy-1, a neuronal glycoprotein, binds to this integrin inducing Connexin43 (Cx43) hemichannel (HC) opening, ATP release, and astrocyte migration. Despite such insight, important links and molecular events leading to astrogliosis remain to be defined. Using bioinformatics approaches, we analyzed different Gene Expression Omnibus datasets to identify changes occurring in reactive astrocytes as compared to astrocytes from the normal mouse brain. In silico analysis was validated by both qRT-PCR and immunoblotting using reactive astrocyte cultures from the normal rat brain treated with TNF and from the brain of a hSOD1 <sup>G93A</sup> transgenic mouse model. We evaluated the phosphorylation of Cx43 serine residue 373 (S373) by AKT and ATP release as a functional assay for HC opening. In vivo experiments were also performed with an AKT inhibitor (AKTi). The bioinformatics analysis revealed that genes of the PI3K/AKT signaling pathway were among the most significantly altered in reactive astrocytes. mRNA and protein levels of PI3K, AKT, as well as Cx43, were elevated in reactive astrocytes from normal rats and from hSOD1 <sup>G93A</sup> transgenic mice, as compared to controls. In vitro, reactive astrocytes stimulated with Thy-1 responded by activating AKT, which phosphorylated S373Cx43. Increased pS373Cx43 augmented the release of ATP to the extracellular medium and AKTi inhibited these Thy-1-induced responses. Furthermore, in an in vivo model of inflammation (brain damage), AKTi decreased the levels of astrocyte reactivity markers and S373Cx43 phosphorylation. Here, we identify changes in the PI3K/AKT molecular signaling network and show how they participate in astrogliosis by regulating the HC protein Cx43. Moreover, because HC opening and ATP release are important in astrocyte reactivity, the phosphorylation of Cx43 by AKT and the associated increase in ATP release identify a potential therapeutic window of opportunity to limit the adverse effects of astrogliosis

Constraining the electric charges of some astronomical bodies in Reissner-Nordstrom spacetimes and generic r^-2-type power-law potentials from orbital motions

We put model-independent, dynamical constraints on the net electric charge Q of some astronomical and astrophysical objects by assuming that their exterior spacetimes are described by the Reissner-Nordstroem metric, which induces an additional potential U_RN \propto Q^2 r^-2. Our results extend to other hypothetical power-law interactions inducing extra-potentials U_pert = r^-2 as well (abridged).Comment: LaTex2e, 16 pages, 3 figures, no tables, 128 references. Version matching the one at press in General Relativity and Gravitation (GRG). arXiv admin note: substantial text overlap with arXiv:1112.351

Aggregation of integrins and RhoA activation are required for Thy-1-induced morphological changes in astrocytes.

Thy-1, a cell adhesion molecule abundantly expressed in mammalian neurons, binds to a beta(3)-containing integrin on astrocytes and thereby stimulates the assembly of focal adhesions and stress fibers. Such events lead to morphological changes in astrocytes that resemble those occurring upon injury in the brain. Extracellular matrix proteins, typical integrin ligands, bind to integrins and promote receptor clustering as well as signal transduction events that involve small G proteins and cytoskeletal changes. Here we investigated the possibility that the cell surface protein Thy-1, when interacting with a beta(3)-containing integrin on astrocytes, could trigger signaling events similar to those generated by extracellular matrix proteins. DI-TNC(1) astrocytes were stimulated with Thy-1-Fc immobilized on beads, and increased RhoA activity was confirmed using an affinity precipitation assay. The effect of various inhibitors on the cellular response was also studied. The presence of Y-27632, an inhibitor of Rho kinase (p160ROCK), a key downstream effector of RhoA, significantly reduced focal adhesion and stress fiber formation induced by Thy-1. Similar effects were obtained when astrocytes were treated with C3 transferase, an inhibitor of RhoA. Alternatively, astrocytes were transfected with an expression vector encoding fusion proteins of enhanced green fluorescent protein with either the Rho-binding domain of Rhotekin, which blocks RhoA function, or the dominant-negative N19RhoA mutant. In both cases, Thy-1-induced focal adhesion formation was inhibited. Furthermore, we observed that RhoA activity after stimulation with soluble Thy-1-Fc molecule was augmented upon further cross-linking using protein A-Sepharose beads. The same was shown by cross-linking beta(3)-containing integrin with anti-beta(3) antibodies. Together, these results indicate that Thy-1-mediated astrocyte stimulation depended on beta(3) integrin clustering and the resulting increase in RhoA activity

Sunscreen effects in skin analyzed by photoacoustic spectroscopy

In this work, photoacoustic spectroscopy (PAS) was employed to characterize samples of commercially available sunscreen (SPF15) and the system formed by sunscreen plus skin (topically applied sunscreen). Measurements were performed at 70Hz, in the wavelength range that corresponds to most of the ultraviolet (UV) radiation that reaches Earth. The absorption spectrum of sunscreen was obtained in vitro and in situ., showing that the sunscreen analyzed presents an effective absorption of the UV radiation After that, the PAS technique was used to monitor the absorption kinetics of sunscreen applied to human skin (abdomen) samples, characterizing alterations in the human skin after application of sunscreen. This was done by applying the sunscreen in a skin sample and recording the absorption spectra in regular time intervals, up to 90 minutes after application. Measurements show that light absorption by the system sunscreen plus skin stabilizes between 25 and 45 minutes after sunscreen application. This agrees with the instructions given by the producers about the need of applying the sunscreen at least 30 minutes before sun exposition. The requirement to periodically reapply the sunscreen is confirmed by the progressive decrease in the level of UV absorption as a function of time

Characterization of human skin through photoacoustic spectroscopy

The photoacoustic (PA) technique is based on the absorption of modulated or pulsed light by a sample with subsequent heat generation, generating thermal waves that propagate in the surrounding media. Such waves produce the pressure oscillation detected as the PA signal. In this work, PA spectroscopy was used to characterize different human skin samples with respect to their response to ultraviolet radiation (UVA and UVB, 240nm < $\lambda$ < 400nm). Measurements were performed at 70Hz and 17Hz, using a 1000W Xe arc lamp as the light source. Skin samples were about 0,5cm diameter. It was possible to obtain the absorption spectra of the stratum corneum and of a deeper layer of epidermis; when the lower modulation frequency is utilized, PA spectroscopy characterizes the absorption of the whole epidermis, because in this case the thermal diffusion length is thicker than that of the stratum corneum. PA spectroscopy was also employed to monitor the drying kinetics of the skin. Pre-treatment of the samples included different periods in a drying chamber. Measurements show that the PA spectra changes according to the humidity of the skin. Future work includes detailed monitoring of skin hydration

Percentage of ubiquitinated spermatozoa does not correlate with fertilizing capacity of thawed bovine semen

Contents: In the spermatozoa of some species, the ubiquitin-proteasome system detects altered proteins and tags them for elimination by the proteasome. In some species' ejaculates, a high proportion of ubiquitinated spermatozoa (i.e. those having ubiquitin bound to the altered or damaged membrane proteins) has been related to infertility. The aim of this study was to assess whether the percentage of ubiquitinated spermatozoa relates to fertility of dairy bulls and whether ubiquitination increases during protein remodelling that occurs during in vitro spermatic capacitation. Thirty-two frozen semen straws from four high-fertility (ReproMax�) and four normal-fertility (Normal) Holstein-Friesian sires were evaluated. Ubiquitinated and capacitated spermatozoa were quantified by sperm ubiquitin tag immunoassay and chlortetracycline stain, respectively. Fertilizing capacity of sires was assessed by in vitro fertilization. No differences were found between Normal and ReproMax� sires with regard to the observed percentage of ubiquitinated spermatozoa (42.97���3.69% and 49.68���9.27%, respectively; p�&gt;�0.05). Additionally, no differences were found in the percentage of ubiquitinated spermatozoa as a consequence of spermatic capacitation in either Normal (42.97���3.69% before capacitation vs 44.67���7.5% after; p�&gt;�0.05) or ReproMax� sires (49.68���9.27% before vs 45.05���7.51% after; p�&gt;�0.05). The percentage of ubiquitinated spermatozoa in a thawed sperm samples did not correlate with its in vitro fertilizing capacity; thus, this assay does not prove useful to detect in vivo fertility differences between sires. Additionally, protein degradation occurring during remodelling of the spermatozoon plasma membrane during the capacitation process does not seem to involve the ubiquitin-proteasome system. � 2013 Blackwell Verlag GmbH

Characterization Of Reconstructed Human Skin Using Photoacoustic Spectroscopy

Recent progress in skin culture techniques has led to the development of systems in which the reconstructed human skin obtained exhibits morphologic characteristics similar to those observed in vivo. Reconstructed human skin may be the best substrate for pharmacological tests of topically applied drugs; besides, it can be employed in the treatment of burns wounds and chronic skin ulcers. However, this newly developed material must be validated by comparison with human skin, in order to show that reconstructed skin presents characteristics similar to those of human skin. This was accomplished in the present work, through photoacoustic spectroscopy (PAS) measurements. Results show similarity between reconstructed skin and ex-vivo human skin, validating possible therapeutic and cosmetic treatments to be developed using the reconstructed human skin analyzed in this work. © EDP Sciences/ Societé Italiana di Fisica/Springer-Verlag 2008.1531471474Puzzi, M.B., Rehder, J., Souto, L.R.M., Issa, C.M., (2004) Sao Paulo Med. J., 122, p. 22Souto, L.R.M., (2006) Sao Paulo Med. J., 124, p. 71Cario-André, M., (2002) J. Photoch. Photobiol. B, 68, p. 79Rompe, P.C.B., (2005) J. Phys. IV (France), 125, p. 785Oliveira, S., Barja, P.R., (2006) Proceedings of the Environmental and Health World Congress - EHWC 2006, pp. 341-345. , in (COPEC, Santos)Rosencwaig, A., Gersho, A., (1976) J. Appl. Phys., 47, p. 64Kitchen, S., Bazin, S., (1998) Eletroterapia De Clayton, , 10th edn. (São Paulo, Manole)Nicoletti, M.A., (2002) Cosmetics & Toiletries, 14, p. 46Zhang, X., (2000) Photochem. Photobiol., 71, p. 524Bendit, E.G., Ross, D., (1961) Appl. Spectrosc., 15, p. 10