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Human Skin Fibroblasts (human + skin_fibroblast)
Selected AbstractsMitochondrial Responses of Normal and Injured Human Skin Fibroblasts Following Low Level Laser Irradiation,An In Vitro StudyPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Innocent L. Zungu Laser irradiation has proved to be very efficient in speeding and improving the quality of healing in pathological conditions of diverse etiologies. However, the mechanisms by which the beneficial effects are attained are not clear. Mitochondria are the primary phototargets during irradiation. The study aimed to establish if laser irradiation had an effect on hypoxic and acidotic cells. The study also aimed to use existing information regarding the possible mechanism of action (established in wounded cells) and apply these principles to acidic and hypoxic irradiated cells to determine whether laser has a stimulatory or inhibitory effect. Cell cultures were modified to simulate conditions of hypoxia (hypoxic gas mixture 95% N2 and 5% O2) and acidosis (pH 6.7) whereas the central scratch model was used to simulate a wound. Cells were irradiated with a helium,neon (632.8 nm, 3 mW cm,2) laser using 5 or 16 J cm,2 on days 1 and 4. Mitochondrial responses were measured 1 or 24 h after laser irradiation by assessing changes in mitochondrial membrane potential (MMP), cyclic AMP, intracellular Ca2+ and adenosine triphosphate (ATP) cell viability. Hypoxia and acidosis significantly reduced MMP when compared with normal nonirradiated control cells. Wounded, hypoxic and acidotic cells irradiated with 5 J cm,2 showed an increase in mitochondrial responses when compared with nonirradiated cells while 16 J cm,2 showed a significant decrease. The study confirmed that laser irradiation with 5 J cm,2 stimulated an increase in intracellular Ca2+ which resulted in an increase in MMP, ATP and cAMP, which ultimately results in photobiomodulation to restore homeostasis of injured cells. [source] Zeolite Encapsulation Decreases TiO2 -photosensitized ROS Generation in Cultured Human Skin Fibroblasts,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2006Biao Shen ABSTRACT Sunscreens protect skin against sunburn. However, studies have demonstrated that UV-irradiated sunscreen components such as titanium dioxide (TiO2) promote the photogeneration of reactive oxygen species (ROS). Because encapsulation of TiO2 within zeolites alters its photocatalytic activity, supra-molecular composites based on NaY zeolite hosts containing TiO2 guests were prepared, and the effects on ROS formation in cells under UVA-irradiation evaluated. DCFH-DA (2,,7,-dichlorofluorescein diacetate) was used as a profluorescent probe to monitor intracellular ROS. The detection of in-tracellular 2,,7,-dichlorofluorescein (DCF) fluorescence by confocal microscopy revealed that DCFH-DA was taken up, hydrolyzed and oxidized by yeast cells and cultured human skin fibroblasts within 20 and 6 min, respectively. Higher DCF fluorescence was observed in fibroblasts following UVA irra-diation in the absence but not in the presence of the radical nitroxide, TEMPOL (4-hydroxy-2,2,6,6-tetramethylpipery-dine-1-oxyl), which exhibits superoxide dismutase-mimetic and catalase-mimetic activity. UVA-induced fluorescence increased by -50% in the presence of 32-nm anatase TiO2 particles and decreased by essentially an equal amount in the presence of TiO2 encapsulated within NaY zeolites (TiO2@NaY). Addition of the uncomplexed NaY host also decreased (by ,30%) the amount of UVA-induced fluorescence but, un-expectedly, the combination of the free guest and host (TiO2@NaY) caused a doubling of the fluorescence. Protection of cells against TiO2 -induced intracellular ROS by encapsulation suggests that supramolecular species may be beneficial in photoprotection of the skin. In contrast, the potentiation of TiO2 -induced ROS by uncomplexed NaY points to a critical role for formulation when free TiO2 is used as a sun screen ingredient. [source] Hesperetin Glucuronide, a Photoprotective Agent Arising from Flavonoid Metabolism in Human Skin Fibroblasts ,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2003Anna R. Proteggente ABSTRACT There is considerable interest in the biological properties of flavonoids in terms of their antioxidant and cytoprotective actions. The interaction of the flavanone hesperetin with human skin fibroblasts (FEK4) has revealed the potential for metabolism to hesperetin glucuronide and its subsequent extrusion. As a consequence of this observation, the effectiveness of hesperetin glucuronides, in comparison with that of the aglycone form, in protecting against UV-A radiation has been investigated. The results indicate that hesperetin glucuronides, but not hesperetin, protect against UV-A-induced necrotic cell death. [source] Human skin fibroblasts: From mesodermal to hepatocyte-like differentiation,HEPATOLOGY, Issue 5 2007Philippe A. Lysy The phenotypic homology of fibroblasts and mesenchymal stem cells (MSCs) has been recently described. Our study investigated the in vitro potential of human skin fibroblasts to differentiate into mesodermal (osteocyte and adipocyte) and endodermal (hepatocyte) cell lineages by comparison with human bone marrow (hBM) MSCs. The endodermal potential of fibroblasts was then explored in vivo in a mouse model of liver injury. Fibroblasts were able to acquire osteocyte and adipocyte phenotypes as assessed by cytochemistry and gene expression analyses. After exposure to a specific differentiation cocktail, these cells presented hepatocyte-like morphology and acquired liver-specific markers on protein and gene expression levels. Furthermore, these fibroblast-derived hepatocyte-like cells (FDHLCs) displayed the ability to store glycogen and synthesize small amounts of urea. By gene expression analysis, we observed that fibroblasts remained in a mesenchymal-epithelial transition state after hepatocyte differentiation. Moreover, FDHLCs lost their hepatocyte-like phenotype after dedifferentiation. In vivo, human fibroblasts infused directly into the liver of hepatectomized severe combined immunodeficient (SCID) mice engrafted in situ and expressed hepatocyte markers (albumin, alpha-fetoprotein, and cytokeratin 18) together with the mesodermal marker fibronectin. Despite lower liver-specific marker expression, the in vitro and in vivo differentiation profile of fibroblasts was comparable to that of mesenchymal-derived hepatocyte-like cells (MDHLCs). In conclusion, our work demonstrates that human skin fibroblasts are able to display mesodermal and endodermal differentiation capacities and provides arguments that these cells share MSCs features both on the phenotypic and functional levels. (HEPATOLOGY 2007;46:1574,1585.) [source] Varying ratios of wavelengths in dual wavelength LED photomodulation alters gene expression profiles in human skin fibroblastsLASERS IN SURGERY AND MEDICINE, Issue 6 2010D.H. McDaniel MD Abstract Background and Objective LED photomodulation has been shown to profoundly influence cellular behavior. A variety of parameters with LED photomodulation can alter cellular response in vitro. The effects of one visible and one infrared wavelength were evaluated to determine the optimal ratio to produce a net increase in dermal collagen by altering the ratio of total energy output of each wavelength. The ratio between the two wavelengths (590 and 870,nm) was shifted in 25% increments. Study Design/Materials and Methods Human skin fibroblasts in culture were exposed to a 590/870,nm LED array with total combined energy density fixed at 4.0,mW/cm.. The ratio of 590/870,nm tested parameters were: 100/0%, 75/25%, 50/50%, 25/75%, and 0/100%. These ratios were delivered using pulsed duty cycle of exposure (250,milliseconds "on" time/100,milliseconds "off" time/100,pulses) for a total energy fluence of 0.1,J/cm.. Gene expression was examined using commercially available extra cellular matrix and adhesion molecule RT PCR Arrays (SA Biosciences, Fredrick, MD) at 24,hours post-exposure. Results Different expression profiles were noticed for each of the ratios studied. Overall, there was an average (in an 80 gene array) of 6% expression difference in up or downregulation between the arrays. The greatest increase in collagen I and decrease in collagenase (MMP-1) was observed with 75/25% ratio of 590/870,nm. The addition of increasing proportions of IR wavelengths causes alteration in gene expression profile. The ratios of the wavelengths caused variation in magnitude of expression. Conclusions Cell metabolism and gene expression can be altered by simultaneous exposure to multiple wavelengths of low energy light. Varying the ratios of specific wavelength intensity in both visible and near infrared light therapy can strongly influence resulting fibroblast gene expression patterns. Lasers Surg. Med. 42:540,545, 2010. © 2010 Wiley,Liss, Inc. [source] Water soluble fraction of solar-simulated light-exposed crude oil generates phosphorylation of histone H2AX in human skin cells under UVA exposureENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2007Yuko Ibuki Abstract Crude oil contains compounds, which have toxic and cancer-causing properties to humans. The oil spilled in environments is usually exposed to sunlight; however, the toxicity of sunlight-exposed oil is poorly understood. In this study, we found that the water soluble fraction (WSF) of crude oil irradiated with solar-simulated light (SSL) generated phosphorylation of histone H2AX (,-H2AX) in human skin cells under UVA irradiation, which was due to the formation of DNA double strand breaks (DSBs). Crude oil was exposed to SSL for ,7 days. The WSF obtained from unexposed crude oil showed no toxicity, whereas the WSF obtained from crude oil pre-exposed to SSL induced acute cell death on exposure to UVA irradiation (induction of phototoxicity), which was more remarkable in human skin fibroblasts than human skin keratinocytes. ,-H2AX was detected in both cell lines immediately after treatment with the WSF plus UVA. Interestingly, ,-H2AX was detectable even at low SSL- and UVA-doses, which induced no cytotoxicity. The WSF of crude oil irradiated with SSL, generated DSBs under UVA irradiation, which were detected by biased sinusoidal field gel electrophoresis. This was confirmed using xrs-5 cells isolated from CHO-K1 cells, which are deficient in a repair enzyme for DSBs; the WSF plus UVA induced a more dramatic decrease in survival in xrs-5 cells than CHO-K1 cells. These findings demonstrate that exposure of crude oil to sunlight makes the WSF phototoxic, generating DSBs accompanying the appearance of ,-H2AX in human skin cells. Environ. Mol. Mutagen., 2007. © 2007 Wiley-Liss, Inc. [source] Sterol-induced upregulation of phosphatidylcholine synthesis in cultured fibroblasts is affected by the double-bond position in the sterol tetracyclic ring structureFEBS JOURNAL, Issue 21 2000Petra Leppimäki We have examined how a specific enrichment of cultured fibroblasts with various sterols (cholesterol, lathosterol, 7-dehydrocholesterol, allocholesterol and dihydrocholesterol) regulate synthesis de novo of phosphatidylcholine, cholesterol and cholesteryl (or steryl) esters in human skin fibroblasts. When human skin fibroblasts were incubated for 1 h with 130 µm cholesterol/CyD complexes, the mass of cellular free cholesterol increased by 100 nmol·mg,1 protein (from 90 nmol·mg,1 to 190 nmol·mg,1 protein). A similar exposure of cells to different sterol/CyD complexes increased the cell sterol content between 38 and 181 nmol sterol per mg cell protein. In cholesterol-enriched cells, the rate of phosphatidylcholine synthesis was doubled compared to control cells, irrespective of the type of precursor used ([3H]choline, [3H]palmitic acid, or [14C]glycerol). Enrichment of fibroblasts with 7-dehydrocholesterol, allocholesterol, or dihydrocholesterol also upregulated phosphatidylcholine synthesis, whereas cells enriched with lathosterol failed to upregulate their phosphatidylcholine synthesis. The activity of membrane-bound CTP:phosphocholine cytidylyltransferase, the rate-limiting enzyme, was increased by 47 ± 4% in cholesterol-enriched cells whereas its activity was unchanged in lathosterol-enriched cells. Sterol enrichment with all tested sterols (including lathosterol) down-regulated acetate-incorporation into cholesterol, and upregulated sterol esterification in the sterol-enriched fibroblasts. Using 31P-NMR to measure the lamellar-to-hexagonal (L,,HII) phase transition in multilamellar lipid dispersions, lathosterol-containing membranes underwent their transition at significantly higher temperatures compared to membranes containing any of the other sterols. In a system with 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphoethanolamine and either cholesterol or lathosterol (70 : 30 mol/mol), differential scanning calorimetry also revealed that the L,,HII -transition occurred at a higher temperature with lathosterol compared to either cholesterol, allocholesterol, or dihydrocholesterol. These findings together suggest that there may exist a correlation between the propensity of a sterol to stabilize the L,,HII -transition and its capacity to upregulate the activity of CTP:phosphocholine cytidylyltransferase in cells. [source] Human skin fibroblasts: From mesodermal to hepatocyte-like differentiation,HEPATOLOGY, Issue 5 2007Philippe A. Lysy The phenotypic homology of fibroblasts and mesenchymal stem cells (MSCs) has been recently described. Our study investigated the in vitro potential of human skin fibroblasts to differentiate into mesodermal (osteocyte and adipocyte) and endodermal (hepatocyte) cell lineages by comparison with human bone marrow (hBM) MSCs. The endodermal potential of fibroblasts was then explored in vivo in a mouse model of liver injury. Fibroblasts were able to acquire osteocyte and adipocyte phenotypes as assessed by cytochemistry and gene expression analyses. After exposure to a specific differentiation cocktail, these cells presented hepatocyte-like morphology and acquired liver-specific markers on protein and gene expression levels. Furthermore, these fibroblast-derived hepatocyte-like cells (FDHLCs) displayed the ability to store glycogen and synthesize small amounts of urea. By gene expression analysis, we observed that fibroblasts remained in a mesenchymal-epithelial transition state after hepatocyte differentiation. Moreover, FDHLCs lost their hepatocyte-like phenotype after dedifferentiation. In vivo, human fibroblasts infused directly into the liver of hepatectomized severe combined immunodeficient (SCID) mice engrafted in situ and expressed hepatocyte markers (albumin, alpha-fetoprotein, and cytokeratin 18) together with the mesodermal marker fibronectin. Despite lower liver-specific marker expression, the in vitro and in vivo differentiation profile of fibroblasts was comparable to that of mesenchymal-derived hepatocyte-like cells (MDHLCs). In conclusion, our work demonstrates that human skin fibroblasts are able to display mesodermal and endodermal differentiation capacities and provides arguments that these cells share MSCs features both on the phenotypic and functional levels. (HEPATOLOGY 2007;46:1574,1585.) [source] Sodium valproate inhibits glucose transport and exacerbates Glut1-deficiency in vitroJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2005Hei Yi Wong Abstract Anticonvulsant sodium valproate interferes with brain glucose metabolism. The mechanism underlying such metabolic disturbance is unclear. We tested the hypothesis that sodium valproate interferes with cellular glucose transport with a focus on Glut1 since glucose transport across the blood-brain barrier relies on this transporter. Cell types enriched with Glut1 expression including human erythrocytes, human skin fibroblasts, and rat astrocytes were used to study the effects of sodium valproate on glucose transport. Sodium valproate significantly inhibited Glut1 activity in normal and Glut1-deficient erythrocytes by 20%,30%, causing a corresponding reduction of Vmax of glucose transport. Similarly, in primary astrocytes as well as in normal and Glut1-deficient fibroblasts, sodium valproate inhibited glucose transport by 20%,40% (P,<,0.05), accompanied by an up to 60% downregulation of GLUT1 mRNA expression (P,<,0.05). In conclusion, sodium valproate inhibits glucose transport and exacerbates Glut1 deficiency in vitro. Our findings imply the importance of prudent use of sodium valproate for patients with compromised Glut1 function. J. Cell. Biochem. © 2005 Wiley-Liss, Inc. [source] Stress-induced responses of human skin fibroblasts in vitro reflect human longevityAGING CELL, Issue 5 2009Pim Dekker Summary Unlike various model organisms, cellular responses to stress have not been related to human longevity. We investigated cellular responses to stress in skin fibroblasts that were isolated from young and very old subjects, and from offspring of nonagenarian siblings and their partners, representatives of the general population. Fibroblasts were exposed to rotenone and hyperglycemia and assessed for senescence-associated ,-galactosidase (SA-,-gal) activity by flow cytometry. Apoptosis/cell death was measured with the Annexin-V/PI assay and cell-cycle analysis (Sub-G1 content) and growth potential was determined by the colony formation assay. Compared with fibroblasts from young subjects, baseline SA-,-gal activity was higher in fibroblasts from old subjects (P = 0.004) as were stress-induced increases (rotenone: P < 0.001, hyperglycemia: P = 0.027). For measures of apoptosis/cell death, fibroblasts from old subjects showed higher baseline levels (Annexin V+/PI+ cells: P = 0.040, Sub-G1: P = 0.014) and lower stress-induced increases (Sub-G1: P = 0.018) than fibroblasts from young subjects. Numbers and total size of colonies under nonstressed conditions were higher for fibroblasts from young subjects (P = 0.017 and 0.006, respectively). Baseline levels of SA-,-gal activity and apoptosis/cell death were not different between fibroblasts from offspring and partner. Stress-induced increases were lower for SA-,-gal activity (rotenone: P = 0.064, hyperglycemia: P < 0.001) and higher for apoptosis/cell death (Annexin V+/PI, cells: P = 0.041, Annexin V+/PI+ cells: P = 0.008). Numbers and total size of colonies under nonstressed conditions were higher for fibroblasts from offspring (P = 0.001 and 0.024, respectively) whereas rotenone-induced decreases were lower (P = 0.008 and 0.004, respectively). These data provide strong support for the hypothesis that in vitro cellular responses to stress reflect the propensity for human longevity. [source] Varying ratios of wavelengths in dual wavelength LED photomodulation alters gene expression profiles in human skin fibroblastsLASERS IN SURGERY AND MEDICINE, Issue 6 2010D.H. McDaniel MD Abstract Background and Objective LED photomodulation has been shown to profoundly influence cellular behavior. A variety of parameters with LED photomodulation can alter cellular response in vitro. The effects of one visible and one infrared wavelength were evaluated to determine the optimal ratio to produce a net increase in dermal collagen by altering the ratio of total energy output of each wavelength. The ratio between the two wavelengths (590 and 870,nm) was shifted in 25% increments. Study Design/Materials and Methods Human skin fibroblasts in culture were exposed to a 590/870,nm LED array with total combined energy density fixed at 4.0,mW/cm.. The ratio of 590/870,nm tested parameters were: 100/0%, 75/25%, 50/50%, 25/75%, and 0/100%. These ratios were delivered using pulsed duty cycle of exposure (250,milliseconds "on" time/100,milliseconds "off" time/100,pulses) for a total energy fluence of 0.1,J/cm.. Gene expression was examined using commercially available extra cellular matrix and adhesion molecule RT PCR Arrays (SA Biosciences, Fredrick, MD) at 24,hours post-exposure. Results Different expression profiles were noticed for each of the ratios studied. Overall, there was an average (in an 80 gene array) of 6% expression difference in up or downregulation between the arrays. The greatest increase in collagen I and decrease in collagenase (MMP-1) was observed with 75/25% ratio of 590/870,nm. The addition of increasing proportions of IR wavelengths causes alteration in gene expression profile. The ratios of the wavelengths caused variation in magnitude of expression. Conclusions Cell metabolism and gene expression can be altered by simultaneous exposure to multiple wavelengths of low energy light. Varying the ratios of specific wavelength intensity in both visible and near infrared light therapy can strongly influence resulting fibroblast gene expression patterns. Lasers Surg. Med. 42:540,545, 2010. © 2010 Wiley,Liss, Inc. [source] Zeolite Encapsulation Decreases TiO2 -photosensitized ROS Generation in Cultured Human Skin Fibroblasts,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2006Biao Shen ABSTRACT Sunscreens protect skin against sunburn. However, studies have demonstrated that UV-irradiated sunscreen components such as titanium dioxide (TiO2) promote the photogeneration of reactive oxygen species (ROS). Because encapsulation of TiO2 within zeolites alters its photocatalytic activity, supra-molecular composites based on NaY zeolite hosts containing TiO2 guests were prepared, and the effects on ROS formation in cells under UVA-irradiation evaluated. DCFH-DA (2,,7,-dichlorofluorescein diacetate) was used as a profluorescent probe to monitor intracellular ROS. The detection of in-tracellular 2,,7,-dichlorofluorescein (DCF) fluorescence by confocal microscopy revealed that DCFH-DA was taken up, hydrolyzed and oxidized by yeast cells and cultured human skin fibroblasts within 20 and 6 min, respectively. Higher DCF fluorescence was observed in fibroblasts following UVA irra-diation in the absence but not in the presence of the radical nitroxide, TEMPOL (4-hydroxy-2,2,6,6-tetramethylpipery-dine-1-oxyl), which exhibits superoxide dismutase-mimetic and catalase-mimetic activity. UVA-induced fluorescence increased by -50% in the presence of 32-nm anatase TiO2 particles and decreased by essentially an equal amount in the presence of TiO2 encapsulated within NaY zeolites (TiO2@NaY). Addition of the uncomplexed NaY host also decreased (by ,30%) the amount of UVA-induced fluorescence but, un-expectedly, the combination of the free guest and host (TiO2@NaY) caused a doubling of the fluorescence. Protection of cells against TiO2 -induced intracellular ROS by encapsulation suggests that supramolecular species may be beneficial in photoprotection of the skin. In contrast, the potentiation of TiO2 -induced ROS by uncomplexed NaY points to a critical role for formulation when free TiO2 is used as a sun screen ingredient. [source] Hesperetin Glucuronide, a Photoprotective Agent Arising from Flavonoid Metabolism in Human Skin Fibroblasts ,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2003Anna R. Proteggente ABSTRACT There is considerable interest in the biological properties of flavonoids in terms of their antioxidant and cytoprotective actions. The interaction of the flavanone hesperetin with human skin fibroblasts (FEK4) has revealed the potential for metabolism to hesperetin glucuronide and its subsequent extrusion. As a consequence of this observation, the effectiveness of hesperetin glucuronides, in comparison with that of the aglycone form, in protecting against UV-A radiation has been investigated. The results indicate that hesperetin glucuronides, but not hesperetin, protect against UV-A-induced necrotic cell death. [source] Regulation of 1-,, 25-Dihydroxyvitamin D3 on Interleukin-6 and Interleukin-8 Induced by Sulfur Mustard (HD) on Human Skin Cells,BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2003Carmen M. Arroyo Stimulation of human skin fibroblasts with sulfur mustard (10,4 M for 24 hr at 37°) resulted in approximately a 5 times increase in the secretion of interleukin-6 and over a 10 times increase for interleukin-8, which was inhibited by 1-,, 25 (OH)2D3, at ,10,9 M. 1-,, 25 (OH)2D3 also suppressed interleukin-8 secretion by 5 times and interleukin-6 by 4 times on sulfur mustard-stimulated human epidermal keratinocytes at concentrations , 10,9 M. The effect of 1-,, 25 (OH)2D3 was dose-dependent for the suppression of interleukin-6 and interleukin-8 induced by sulfur mustard on human skin fibroblasts/human epidermal keratinocytes, apparent at nanomolar concentrations. Our results indicate that the suppression of these inflammatory mediators by 1-,, 25 (OH)2D3 is dependent on the source of the primary cultures, cell densities, and kinetics of pretreatments. In contrast to the inhibition of cytokine/chemokine production, cell proliferation was enhanced by almost 1.7 times on treated human epidermal keratinocytes with 1-,, 25 (OH)2D3 (1×10,9 M) after sulfur mustard-stimulation (10,4 M for 24 hr at 37°C). The observed enhancement diversified based on cell density, and kinetics of pretreatment with a maximal synergism (s) observed at 1×10,9 M. Photomicrographs show typical signs of cellular degeneration caused by sulfur mustard such as chromatin condensation. The observed cellular degeneration was lessened when human epidermal keratinocytes were treated with 1-,, 25 (OH)2D3 (2×10,9 M). 1-,, 25(OH)2D3 could be an alternative treatment for cutaneous inflammation disorders caused by sulfur mustard because we have demonstrated its ability to suppress inflammatory mediators and enhanced cell proliferation in human skin cells stimulated with sulfur mustard. [source] Power line frequency electromagnetic fields do not increase the rate of protein synthesis in human skin fibroblasts as previously reportedBIOELECTROMAGNETICS, Issue 7 2003Biao Shi Abstract Rodemann et al. [Rodemann et al. (1987): Biochem Biophys Res Commun 145:1,9] reported that human skin fibroblasts increase their rate of protein synthesis by as much as over ninefold in response to long term exposure to 20 Hz, 8.4 mT (84 G) magnetic fields. Here we report studies of protein synthesis using an identical cell type, exposure conditions, and the same means of measuring protein synthetic rates. Our initial goal was to determine if the earlier results could be replicated, but we found an inconsistency in the earlier protocol. It exposed cells to [3H]leucine for 6 h prior to measuring incorporation into protein. We found, however, that 24 h is required for [3H]leucine to reach a steady state distribution across the cells' plasma membranes. In addition, we typically measured 100,200 cpm/thousand cells. This is four- to eightfold higher than the 19,28 cpm/1000 cells previously reported. Using these conditions, we could find no significant difference in protein synthesis rates between control cells and cells exposed for up to three weeks in an identical electromagnetic field. In addition, we investigated the effects of a 60 Hz field since that is the frequency used for electric power distribution in the United States. Again, we could find no significant effect of this field on rates of protein synthesis, even after 21 days of exposure. Bioelectromagnetics 24:465,472, 2003. © 2003 Wiley-Liss, Inc. [source] The effect of narrowband ultraviolet B on the expression of matrix metalloproteinase-1, transforming growth factor-,1 and type I collagen in human skin fibroblastsCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 2 2007C. P. Choi Summary Background., Ultraviolet (UV) irradiation induces chronic skin diseases, such as skin cancer and photoageing, and the mechanisms of this skin damage are associated with the upregulation of matrix metalloproteinases (MMPs) and decreased collagen synthesis. Narrowband ultraviolet B (NB-UVB) radiation is a relatively new treatment modality for vitiligo and psoriasis. However, the mechanism of NB-UVB action on photoageing is not completely understood. Aims., We investigated the effects of NB-UVB on the expression of MMP-1, transforming growth factor (TGF)-,1 and type I collagen in cultured human skin fibroblasts. Methods., Cultured human fibroblasts were irradiated with either NB-UVB (50,800 mJ/cm2) or broadband UVB (BB-UVB; 25 mJ/cm2). The expression of MMP-1, TGF-,1 and type I collagen mRNA was determined by reverse-transcription PCR. Expression of MMP-1 and TGF-,1 protein was determined by ELISA and that of type I collagen by Western blotting. Results., NB-UVB induced the expression of MMP-1 and reduced the expression of TGF-,1 and type I collagen at the mRNA and protein levels in a dose-dependent manner. The expression of type I collagen protein decreased more after irradiation with 25 mJ/cm2 of BB-UVB than 400 mJ/cm2 of NB-UVB. Conclusions., This study indicates that NB-UVB irradiation reduces type I collagen synthesis in human skin fibroblasts by inhibiting TGF-,1 expression and stimulating the release of MMP-1. It also suggested that the photoageing-related effects of NB-UVB are weaker than those of BB-UVB in vitro. [source] | |||||||||||||