| 1. |
- Bauer, Brigitte, 1978, et al.
(författare)
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Modification and expulsion of keratins by human epidermal keratinocytes upon hapten exposure in vitro.
- 2011
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Ingår i: Chemical research in toxicology. - : American Chemical Society (ACS). - 1520-5010 .- 0893-228X. ; 24:5, s. 737-43
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Tidskriftsartikel (refereegranskat)abstract
- Allergic contact dermatitis is the most prevalent form of human immunotoxicity. It is caused by reactive low molecular weight chemicals, that is, haptens, coming in contact with the skin where hapten-peptide complexes are formed, activating the immune system. By using sensitizing fluorescent thiol-reactive haptens, that is, bromobimanes, we show how keratinocytes respond to hapten exposure in vitro and reveal, for the first time in a living system, an exact site of haptenation. Rapid internalization and reaction of haptens with keratin filaments were visualized. Subsequently, keratinocytes respond in vitro to hapten exposure by release of membrane blebs, which contain haptenated keratins 5 and 14. Particularly, cysteine 54 of K5 was found to be a specific target. A mechanism is proposed where neoepitopes, otherwise hidden from the immune system, are released after hapten exposure via keratinocyte blebbing. The observed expulsion of modified keratins by keratinocytes in vitro might play a role during hapten sensitization in vivo and should be subject to further investigations.
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| 2. |
- Bender, Johanna, 1975, et al.
(författare)
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Lipid cubic phases in topical drug delivery: Visualization of skin distribution using two-photon microscopy
- 2008
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Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 129:3, s. 163-169
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of sulphorhodamine B (SRB), a fluorescent hydrophilic model drug, was investigated in human skin after passive diffusion using four different topical delivery systems. The delivery vehicles applied were two bicontinuous lipid cubic systems, a commercial ointment and water. The lipid cubic systems consisted of either monoolein (MO) or phytantriol (PT) and water. The formulations were applied on full-thickness human skin during 24 h. Thereafter the samples were investigated using two-photon microscopy (TPM). The TPM system consisted of an inverted microscope with a 40× water-immersion objective, laser scan-box, and a pulsed femtosecond titanium:sapphire laser operating at 780 nm. The fluorescence was detected using a 560 nm long-pass filter. Sequential optical sectioning was performed, resulting in images obtained at different tissue depths. TPM revealed that SRB mainly penetrates the skin via the intercellular lipid matrix. Samples exposed to the cubic phases showed a higher accumulation of SRB in micro-fissures, from which a fluorescent network of threadlike structures spread laterally in the tissue. These structures were also detected in some of the ointment samples, but not as frequent. The penetration of SRB into the stratum granulosum was deduced from the fluorescence of SRB present inside polygonal keratinocytes with cell nuclei. Higher SRB fluorescence was obtained in the outermost layer of the epidermis using the bicontinuous cubic phases, compared to when using the reference formulations. Thus, our results suggest that the dominating delivery route using the cubic phases is via micro-fissures caused by microscopic clustering of the keratinocytes in the skin. From these micro--fissures hydrophilic compounds, here modeled by SRB, can diffuse into the surrounding intercellular lipid matrix acting like a source for sustained release.
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| 3. |
- Ericson, Marica B, 1974, et al.
(författare)
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Two-photon laser-scanning fluorescence microscopy applied for studies of human skin
- 2008
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-0648 .- 1864-063X. ; 1:4, s. 320-330
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon laser scanning fluorescence microscopy (TPM) has been shown to be advantageous for imaging optically turbid media such as human skin. The ability of performing three-dimensional imaging without presectioning of the samples makes the technique not only suitable for noninvasive diagnostics but also for studies of topical delivery of xenobiotics. Here, TPM is used as a method to visualize both autofluorescent and exogenous fluorophores in skin. Samples exposed to sulforhodamine B have been scanned from two directions to investigate attenuation effects. It is shown that optical effects play a major role. Thus, TPM is excellent for visualizing the localization and distribution of fluorophores in human skin, although quantification might be difficult. Furthermore, an image-analysis algorithm has been implemented to facilitate interpretation of TPM images of autofluorescent features of nonmelanoma skin cancer obtained ex vivo. The algorithm was designed to detect cell nuclei and currently has a sensitivity and specificity of 82% and 78% to single cell nuclei. However, in order to detect multinucleated cells, the algorithm needs further development. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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| 4. |
- Frykholm, Erik, 1985-, et al.
(författare)
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Applicability of a supramaximal high-intensity interval training program for older adults previously not engaged in regular exercise : analyses of secondary outcomes from the Umeå HIT Study
- 2024
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Ingår i: Psychology of Sport And Exercise. - : Elsevier. - 1469-0292 .- 1878-5476. ; 73
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Tidskriftsartikel (refereegranskat)abstract
- This analysis of secondary outcomes investigated the applicability of supramaximal high-intensity interval training (HIT) with individually prescribed external intensity performed on stationary bicycles. Sixty-eight participants with a median (min; max) age of 69 (66; 79), at the time not engaged in regular exercise were randomized to 25 twice-weekly sessions of supramaximal HIT (20-min session with 10 × 6-s intervals) or moderate-intensity training (MIT, 40-min session with 3 × 8-min intervals). The primary aim was outcomes on applicability regarding; adherence to prescribed external interval intensity, participant reported positive and negative events, ratings of perceived exertion (RPE 6–20), and affective state (Feeling Scale, FS -5–5). A secondary aim was to investigate change in exercise-related self-efficacy (Exercise Self-Efficacy Scale) and motivation (Behavioural Regulations in Exercise Questionnaire-2). Total adherence to the prescribed external interval intensity was [median (min; max)] 89 % (56; 100 %) in supramaximal HIT, and 100 % (95; 100 %) in MIT. The supramaximal HIT group reported 60 % of the positive (112 of 186) and 36 % of the negative (52 of 146) events. At the end of the training period, the median (min; max) session RPE was 15 (12; 17) for supramaximal HIT and 14 (9; 15) for MIT. As for FS, the median last within-session rating was 3 (−1; 5) for supramaximal HIT and 3 (1; 5) for MIT. Exercise-related motivation increased (mean difference in Relative Autonomy Index score = 1.54, 95 % CI [0.69; 2.40]), while self-efficacy did not change (mean difference = 0.55, 95 % CI [-0.75; 1.82]), regardless of group. This study provide support for supramaximal HIT in supervised group settings for older adults.
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| 5. |
- Guldbrand, Stina, 1970, et al.
(författare)
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Measuring the diffusion of fluorophores in human skin by two-photon fluorescence correlation spectroscopy combined with measurements of point spread function
- 2011
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Ingår i: MULTIPHOTON MICROSCOPY scigloo.IN THE BIOMEDICAL SCIENCES XI Book Series: Proceedings of SPIE. ; 7903, s. 7903291-7903296
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon excitation fluorescence correlation spectroscopy (TPFCS) has been used in combination with measurements of the point spread function (PSF), for quantitative analysis of fluorophores in excised human skin. Measurements have been performed at depths between 0 and 40 μm. The PSF, measured as full width at half maximum, was found not to depend on the depth. Measurements revealed difference in diffusion coefficient depending on extra- or intracellular location of fluorophore. The number of molecules was accumulating close to the surface and then decreased by the depth. The results from our study show that TPFCS can be used for quantitative analyses of fluorescent compounds in human skin.
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| 6. |
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| 7. |
- Guldbrand, Stina, 1970, et al.
(författare)
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Two-photon fluorescence correlation microscopy combined with measurements of point spread function; investigations made in human skin
- 2010
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Ingår i: Optics Express. - 1094-4087. ; 18:15, s. 15289-15302
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon excitation fluorescence correlation spectroscopy (TPFCS) has been applied in connection to measurements of the point spread function (PSF) for quantitative analysis of sulphorhodamine B (SRB) in excised human skin. The PSF was measured using subresolution fluorescent beads embedded in the skin specimen. The PSF, measured as full width at half maximum (FWHM) was found to be 0.41 ± 0.05 μm in the lateral direction, and 1.2 ± 0.4 μm in the axial direction. The molecular diffusion of SRB inside the skin ranged between 0.5 and 15.0 × 10 −8 cm2/s. The diffusion coefficient is not dependent on depths down to 40 μm. The fluorophores were found to accumulate on the upper layers of the skin. This work is the first TPFCS study in human skin. The results show that TPFCS can be used for quantitative analyses of fluorescent compounds in human skin.
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| 8. |
- Guldbrand, Stina, 1970, et al.
(författare)
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Two-photon fluorescence correlation spectroscopy as a tool for measuring molecular diffusion within human skin
- 2013
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Ingår i: European Journal of Pharmaceutics and Biopharmaceutics. - : Elsevier BV. - 0939-6411. ; 84:2, s. 430-436
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for tools enabling quantitative imaging of biological tissue for pharmaceutical applications. In this study, two-photon fluorescence microscopy (TPM) has been combined with fluorescence correlation spectroscopy (FCS), demonstrating proof-of-principle providing quantitative data of fluorophore concentration and diffusion in human skin. Measurements were performed on excised skin exposed to either rhodamine B (RB) or rhodamine B isothiocyanate (RBITC), chosen based on their similarity in fluorescence yield and molecular weight, but difference in chemical reactivity. The measurements were performed at tissue depths in the range 0 and 20 pm, and the diffusion coefficients at skin depths 5 and 10 mu m were found to be significantly different (P < 0.05). Overall median values for the diffusion coefficients were found to be 4.0 x 10(-13) m(2)/s and 2.0 x 10(-13) m(2)/s for RB and RBITC, respectively. These values correspond to the diffusion of a hard sphere with a volume eight times larger for RBITC compared to RB. This indicates that the RBITC have bound to biomolecules in the skin, and the measured signal is obtained from the RBITC-biomolecule complexes, demonstrating the potential of the TPM-FCS method to track molecular interactions in an intricate biological matrix such as human skin.
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| 9. |
- Karlsson, Isabella, et al.
(författare)
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The Fate of a Hapten - From the Skin to Modification of Macrophage Migration Inhibitory Factor (MIF) in Lymph Nodes
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Skin (contact) allergy, the most prevalent form of immunotoxicity in humans, is caused by low molecular weight chemicals (haptens) that penetrate stratum corneum and modify endogenous proteins. The fate of haptens after cutaneous absorption, especially what protein(s) they react with, is largely unknown. In this study the fluorescent hapten tetramethylrhodamine isothiocyanate (TRITC) was used to identify hapten-protein conjugates in the local lymph nodes after topical application, as they play a key role in activation of the adaptive immune system. TRITC interacted with dendritic cells but also with T and B cells in the lymph nodes as shown by flow cytometry. Identification of the most abundant TRITC-modified protein in lymph nodes by tandem mass spectrometry revealed TRITC-modification of the N-terminal proline of macrophage migration inhibitory factor (MIF) - an evolutionary well-conserved protein involved in cell-mediated immunity and inflammation. This is the first time a hapten-modified protein has been identified in lymph nodes after topical administration of the hapten. Most haptens are electrophiles and can therefore modify the N-terminal proline of MIF, which has an unusually reactive amino group under physiological conditions; thus, modification of MIF by haptens may have an immunomodulating role in contact allergy as well as in other immunotoxicity reactions.
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| 10. |
- Kirejev, Vladimir, 1984, et al.
(författare)
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Multiphoton microscopy – a powerful tool in skin research and topical drug delivery science
- 2012
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Ingår i: Journal of Drug Delivery Science and Technology. - 1773-2247. ; 22:3, s. 250-259
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Tidskriftsartikel (refereegranskat)abstract
- Multiphoton microscopy (MPM) has become a powerful complementary tool in biomedical research, enabling non-invasive three-dimensional imaging of tissue with high resolution. The major advantage is that investigations and visualization can be performed without mechanical destruction of the sample through tissue sectioning. This review will give a brief introduction to the technology, accompanied by examples of how the technique can be implemented within the field of skin research. Specifically, MPM has already made it possible to visualize cellular morphology and the cutaneous distribution of topically applied compounds applied to intact skin. MPM provides information that can be used to assess the bioavailability of drugs and to visualize drug penetration pathways into skin. MPM has also been implemented as a tool for obtaining non-invasive tissue biopsy based on skin autofluorescence in connection to diagnostics of skin cancer. We will also briefly present some recent results where MPM has been used to track cyclodextrin based drugs applied topically. Finally, we will discuss some future challenges of the technology, including label-free imaging, multimodal techniques, and quantitative imaging.
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