Chlorogenic Acid UVA–UVB Photostability

Chlorogenic acid is a natural potent antioxidant. It can be used in cosmetics formulations, but for this purpose its photochemical stability should be determined to ensure that the compound will not be degraded after UV radiation exposure. To evaluate this possibility, the concentration of a chlorogenic acid solution was determined by HPLC before and after UVA and UVB irradiation. The results indicate that chlorogenic acid is not degraded under UVA or UVB irradiation.     

Sufficient Vitamin D from Casual Sun Exposure?

Next to the adverse effects of solar UV exposure, the beneficial effects mediated by vitamin D₃ have come into the limelight. The question then is “how much sun exposure do we actually need?” Estimates have been made, but the data are not quite adequate. The groups of Drs. Rhodes and Webb bridged the gap between experiments and everyday life by a study in which 109 volunteers were exposed in mid‐winter to simulated solar UV radiation in summertime clothing at dosages of 1.3 SED three times a week. Thus, 90% reached sufficiently high vitamin D statuses (>50 nmol L⁻¹). In this issue, these researchers transpose these experimental exposures in a cabinet to summertime noon exposures of people walking around for about half an hour in open terrain on a clear day in Manchester, UK. This result is an improvement over earlier estimates and shows that casual mid‐day summer sun exposure should indeed suffice.     

Effect of Low Energy Electron Exposure on Ion Scattering Spectroscopy

The effect of low energy electron (LEE) exposure on ISS, including on the sputter peak and scatter peak as well as on ion neutralization, has been investigated for different samples. Some new results are discussed.     

Biogenic Isoprene Emission Mechanism from ^13CO2 Exposure Experiments

Biogenic isoprene emissions have been believed to be from only photosynthesis processes in plant. However nocturnal isoprene emission from pine is detected. And by feeding ^13CO2 to plants, it is found that both photosynthesis pathway and light independent processes contribute to isoprene emissions.     

Exposure to airborne formaldehyde: Sampling and analytical methods—A review

Air monitoring is the quantitative-qualitative assessment of the extent of pollutants. It is performed to ensure compliance with legislation and to evaluate control measures and mitigation solutions. There are numerous approaches to measure airborne formaldehyde (FA), ranging from passive sampling techniques to remote sensing devices. Research of sampling procedures and analytical methods was performed in a scientific database and on the web to offer a scenario of the devices and techniques that can be used to assess FA exposure. Moreover, in the design of FA assessment, some crucial aspects were considered, such as standard atmosphere generation for devices calibration. This review summarizes the tools and basics used in FA air monitoring, useful to organize a functional monitoring strategy for assessment of FA concentration levels. An insight into the sampling and analysis of FA is provided. Recent advances in solid sorbent technology allow analysts to use these devices coupled to chromatographic instruments. A comparison of the strengths and weaknesses of analytical methods (gas-/liquid-chromatography coupled with mass spectrometry or UV detection, chromogenic, colorimetric, electrochemical determination) and sampling devices (impregnated papers, solid sorbents, liquid sorbents, bubblers, impingers, micro-impingers, denuder samplers, sealed bags, canisters) methods are illustrated. This survey found that a monitoring strategy should be planned considering the most appropriate methodology in terms of costs and practicability. Therefore, it is necessary to know the aspects that can make the chosen strategy suitable and valid for the exposure scenario under investigation.     

Significance of Hydrogen�CDeuterium Exchange at Polyolefin Surfaces on Exposure to Ammonia Low-Pressure Plasma

Since more than 40 years ammonia plasma exposure of polyolefins is used for introduction of primary amino groups. The selectivity of this reaction and the yield in primary amino groups was found to be low. Here, a prominent side-reactions of this process was investigated, the hydrogenation by NH₃ plasma. For identification of hydrogenation ammonia (NH₃) and deuterated ammonia (ND₃) were exposed to polyethylene (h-PE) and fully deuterated polyethylene (d-PE) as well as hexatriacontane (h-HTC) and fully deuterated hexatriacontane (d-HTC) as low-molecular weight model for PE. H?CD exchange was assumed and detected by Time-of-Flight Secondary Ion Mass Spectrometry (ToF?CSIMS), X-ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflectance (ATR-FTIR) and ¹H and ²H Nuclear magnetic Resonance. Results show a significant H?CD exchange within the sampling depth of ATR (2.5 ??m). However, N- and NH₂ introduction was limited to the topmost surface as shown by SIMS and XPS (a few nanometers).     

Exposed Body Surface Area—A Determinate for UV Radiant Energy in Human UV Exposure Studies

Solar ultraviolet (UV) exposure of people and related health risk is mainly examined by estimating the received UV radiant exposure. However, for several effects such as DNA damage, vitamin D photosynthesis or the probability of developing skin cancer, UV radiant energy is important and with that the size of exposed skin area. There is also a complex interaction between body shape and behavior like sun exposure habits, so that careful analysis is necessary when estimating health effects from UV exposure. In this paper, knowledge on body shape and methods of calculating the total body surface area (BSA) are summarized. BSA depends mainly on the height and weight of a person as well as on gender, ethnicity and body shape. BSA and body shape differ significantly between different populations and both change during life. This paper proposes formulas for BSA that consider height, weight, gender, ethnicity and body shape. As the exposed BSA depends on clothing, finally an approach is presented which aims to calculate the size of body parts released by real garments. In summary, this paper will enable future researchers to quantify the exposed BSA by best matching their study population and consequently investigate risks caused by solar UV exposure.     

Differential Activation of Signaling Pathways by UVA and UVB Radiation in Normal Human Epidermal Keratinocytes(†)

Ultraviolet (UV) radiation from the solar spectrum is a major etiological factor for many cutaneous pathologies including cancer. By understanding changes in cell signaling pathways induced by UVA and UVB, novel strategies for prevention and treatment of UV‐related pathologies could be developed. However, much of the information in the literature from various laboratories cannot cross talk because of difficulties associated with the use of ill‐defined light sources and physiologically irrelevant light dosimetry. Herein, we have assessed the effect of exposure of normal human epidermal keratinocytes (NHEK) to UVA (2 and 4 J cm^?2) or UVB (20 and 40 mJ cm^?2) radiation. Employing western blot analysis, we found that exposure of NHEK to UVB, but not UVA, phosphorylates JNK1/2 at Th¹⁸³/Tyr¹⁸⁵, STAT3 at Ser⁷²⁷, AKT at Ser⁴⁷³ and increases c‐Fos expression, whereas exposure to UVA, but not UVB, phosphorylates AKT at Thr³⁰⁸. UVB as well as UVA exposure leads to increased phosphorylation of (1) ERK1/2 at Th²⁰²/Tyr²⁰⁴; (2) p38 at Th¹⁸⁰/Tyr²⁰⁴; (3) STAT3 at Tyr⁷⁰⁵; (4) mTOR at Thr²⁴⁴⁸; and (v) p70S6k at Thr⁴²¹/Ser⁴²⁴; enhanced expression of PI3K (p85) and c‐jun; and nuclear translocation of NFκB proteins. These findings could be considered as a beginning for understanding the differential effects of UVA and UVB in the human skin and may have implications both with respect to risk assessment from exposure to solar UV radiation, and to target interventions against signaling events mediated by UVA and UVB.     

Sex as a Risk Factor for Solar Ultraviolet Radiation Exposure?–Dosimetry in Danish Outdoor Workers

Solar ultraviolet radiation (UVR) exposure is a known risk factor for the development of skin cancer. Heterogeneity in solar UVR exposure may explain the diversity in skin cancer incidence between men and women. This, however, has not previously been investigated in Danish outdoor workers using UVR dosimetry. The aim of this study was to evaluate sex differences in solar UVR dosimetry in Danish outdoor workers on working and leisure days. A cross-sectional design was used to collect dosimetry data during the Danish summer season (May to September). Analysis was based on an electronic questionnaire and dosimetry data from 450 outdoor workers (88 women, 362 men). Dosimetry data were reported as standard erythema dose (SED). The daily median SED (Interquartile range) on working days was 1.6 (2.5) in men and 1.5 (2.1) in women while on leisure days it was 0.5 (1.4) in men and 0.6 (1.3) in women. Analysis by multiple linear regression did not show any association between daily median SED and sex on either working or leisure days. In conclusion, solar UVR exposure in Danish outdoor workers did not vary according to sex.     

Hairless and NFκB Form a Positive Feedback Loop After UVB and TNFα Stimulation(†)

Hairless (HR) is a nuclear protein with corepressor activity whose exact function in the skin remains to be determined. Mutations in both human and mouse Hairless lead to hair loss accompanied by the appearance of papules, a disorder called atrichia with papular lesions. Furthermore, mice with mutations in HR are known to have a higher susceptibility to ultraviolet radiation-induced tumorigenesis, suggesting that HR plays a crucial role in the epidermal UVB response. Using normal human keratinocytes (NHKs) and keratinocytes containing a mutation in HR, we found that HR is an early UVB response gene that negatively regulates NFκB mRNA expression. HR mutant keratinocytes have a dysregulated UVB response that includes increased proliferation and the aberrant activation of NFκB effector genes. Additionally, we show that another UVB response gene, TNFα, negatively regulates HR mRNA expression. TNFα-induced negative regulation of HR occurs through a direct interaction of the p65 subunit with a single NFκB-binding domain located in the HR promoter region. Therefore, we show for the first time that HR and NFκB participate in a positive feedback loop that can be initiated either by UVB or TNFα.     

UVA, UVB and UVC induce differential response signaling pathways converged on the eIF2α phosphorylation

It is clear that solar UV irradiation is a crucial environmental factor resulting in skin diseases partially through activation of cell signaling toward altered gene expression and reprogrammed protein translation. Such a key translational control mechanism is executed by the eukaryotic initiation factor 2α subunit (eIF2α) and the downstream events provoked by phosphorylation of eIF2α at Ser(51) are clearly understood, but the upstream signaling mechanisms on the eIF2α-Ser(51) phosphorylation responses to different types of UV irradiations, namely UVA, UVB and UVC, are still not well elucidated. Herein, our evidence reveals that UVA, UVB and UVC all induce a dose- and time-dependent phosphorylation of eIF2α-Ser(51) through distinct signaling mechanisms. UVA-induced eIF2α phosphorylation occurs through MAPKs, including ERKs, JNKs and p38 kinase, and phosphatidylinositol (PI)-3 kinase. By contrast, UVB-induced eIF2α phosphorylation is through JNKs and p38 kinase, but not ERKs or PI-3 kinase, whereas UVC-stimulated response to eIF2α phosphorylation is via JNKs alone. Furthermore, we have revealed that ATM is involved in induction of the intracellular responses to UVA and UVB, rather than UVC. These findings demonstrate that wavelength-specific UV irradiations activate differential response signaling pathways converged on the eIF2α phosphorylation. Importantly, we also show evidence that a direct eIF2α kinase PKR is activated though phosphorylation by either RSK1 or MSK1, two downstream kinases of MAPKs/PI-3 kinase-mediated signaling pathways.     

胶内差异双向电泳-电喷雾串联质谱筛选UVB损伤皮肤细胞潜在的蛋白质靶标

联用胶内差异双向电泳(2D-DIGE)和高效液相色谱-电喷雾串联质谱(HPLC-nESI MS/MS)鉴定人角质形成细胞HaCaT应答中波紫外线(UVB)损伤的差异表达蛋白,筛选UVB影响皮肤细胞正常生理功能潜在的靶标蛋白.结果表明:UVB辐射明显影响HaCaT细胞的蛋白质表达谱,DeCyder软件在每块DIGE凝胶上...     

Ultraviolet Radiation Exposure and its Impacts on Cutaneous Phosphorylation Signaling in Carcinogenesis: Focusing on Protein Tyrosine Phosphatases†

Sunlight exposure is a significant risk factor for UV-induced deteriorating transformations of epidermal homeostasis leading to skin carcinogenesis. The ability of UVB radiation to cause melanoma, as well as basal and squamous cell carcinomas, makes UVB the most harmful among the three known UV ranges. UVB-induced DNA mutations and dysregulation of signaling pathways contribute to skin cancer formation. Among various signaling pathways modulated by UVB, tyrosine phosphorylation signaling which is mediated by the action of protein tyrosine kinases (PTKs) on specific tyrosine residues is highly implicated in photocarcinogenesis. Following UVB irradiation, PTKs get activated and their downstream signaling pathways contribute to photocarcinogenesis by promoting the survival of damaged keratinocytes and increasing cell proliferation. While UVB activates oncogenic signaling pathways, it can also activate tumor suppressive signaling pathways as initial protective mechanisms to maintain epidermal homeostasis. Tyrosine dephosphorylation is one of the protective mechanisms and is mediated by the action of protein tyrosine phosphatases (PTPs). PTP can counteract UVB-mediated PTK activation and downregulate oncogenic signaling pathways. However, PTPs have not been studied extensively in photocarcinogenesis with previous studies regarding their inactivation induced by UVB. This current review will summarize the recent progress in the protective function of PTPs in epidermal photocarcinogenesis.     

LC Determination of the Skin Exposure to Oxamyl on Greenhouse Workers and Comparison Between DAD and MS–MS Detection

An LC–DAD method was developed to determine residues of oxamyl on greenhouse workers’ skin. The wipe test was used to obtain samples from hands, forearms, neck and gloves of workers taking cactus cuttings 48 h after pesticide treatment. It was validated in a concentration range 50–5,000 ng mL^?1. The results on six workers and ten office employees indicated significant differences particularly in the hand samples. To avoid the overestimation owing to an interfering substance we proceeded to confirm these findings with LC–MS–MS, which found the pesticide only on the surface of the workers’ gloves, proving that there was indeed some UV interference.     

Depression of Calcium Transients After Exposure to High K~+ Solution in Li~+-loaded Frog Twitch Muscle Fibres and Its Reversal by Exogenous Myo-inositol

Using Arsenazo Ⅲ as a myoplasmic calcium indicator, we have studied the calcium transients evoked by voltage-clamp depolarizing pulses in frog twitch muscle fibres which had been temporarily depolarized by 80 mmol/LK~+ in the absence or presence of myoplasmic Li~+. After the high K~+ exposure, for either a short (15 rain) or long(1 h) time, the post-K~+ calcium transients could gradually be restored to the level of the pre-K~+ ones, if the fibres were not loaded with Li~+.In contrast, the post-K~+ calcium transients of Li~+-loaded fibres could not fully recover,and were depressed in a Li~+ concentration-dependent manner.The mean amplitude of the post-K~+ responses recorded more than 3.5 h after 15 min high K~+ exposure was reduced to 56% of pre-K~+ control in the fibres which had been loaded with Li~+ in 20 mmol/L Li~+ Ringer's solution.This depression could be prevented or partially reversed by exogenous myo-inositol.More depression could be induced by 1 h high K~+ exposure, but the presence of exogen     

Phototransformations of selected pharmaceuticals under low-energy UVA–vis and powerful UVB–UVA irradiations in aqueous solutions—the role of natural dissolved organic chromophoric material

The kinetics of simulated low-energy daylight (UVA–vis) and powerful combined ultraviolet B and A (UVB–UVA) induced direct and indirect phototransformations of four pharmaceuticals, i.e., ibuprofen, metoprolol, carbamazepine, and warfarin, which were investigated in dilute solutions of pure laboratory and natural humic waters. The results strengthen the essential function of natural chromophores in dissolved organic material (CDOM) as principal photosensitizer toward indirect phototransformations of pharmaceuticals in natural conditions under available low-energy UVA–vis and slight UVB radiations. The results confirmed that organic micropollutants are able to undergo a direct photolysis if their absorbance spectra overlap the spectral range of the available radiation but only if the radiation is strong enough, e.g., ibuprofen is able to undergo only indirect photolysis via different pathways in all realistic conditions. The action of nitrate anions as photosensitizers in the applied conditions proved to be of little importance. High-performance size-exclusion chromatographic experiments verified that the rate constants obtained under the low-energy UVA–vis and powerful UVB–UVA irradiations for the decreased amounts of the two largest molecular size fractions of CDOM were quite close to the rate constants detected for the increased amounts of the next five molecular size fractions with smaller molecular sizes. The decreased contents of the two largest molecular size fractions correlated quite well with the decreased contents of the studied pharmaceuticals under the low-energy UVA–vis irradiation process but somewhat less under the powerful UVB–UVA irradiation. The photochemically induced decomposition of the CDOM aggregates appears to increase the amounts of smaller molecular size fractions and simultaneously produce via CDOM-stimulated radical reactions indirect structural transformations of pharmaceuticals. Apparent quantum yields were estimated for the transformation–degradation of the two largest molecular-size CDOM aggregates under low-energy UVA–vis and powerful UVB–UVA irradiations. Figure Structural difference between CDOM and pharmaceuticals studies     

Is δ‐Aminolevulinic Acid Dehydratase Rate Limiting in Heme Biosynthesis Following Exposure of Cells to δ‐Aminolevulinic Acid?¶

Understanding the regulation and control of heme/porphyrin biosynthesis is critical for the optimization of the delta-aminolevulinic-acid (ALA)-mediated photodynamic therapy of cancer, in which endogenously produced protoporphyrin IX (PPIX) is the photosensitizer. The human breast cancer cell line MCF-7, the rat mammary adenocarcinoma cell line R3230AC, the mouse mammary tumor cell line EMT-6 and the human mesothelioma cell line H-MESO-1 were used to study ALA-induced PPIX levels and their relationship to delta-aminolevulinic acid dehydratase (ALA-D) activity in vitro. Incubation of these cell lines with 0.5 mM ALA for 3 h resulted in a significant increase in PPIX accumulation, compared with control cells, but there was no significant change in ALA-D activity. Exposure of cells incubated with ALA to 30 mJ/cm2 of fluorescent light, a dose that would cause a 50% reduction in cell proliferation, did not significantly alter the activity of ALA-D. Increasing the activity of porphobilinogen deaminase (PBGD), the enzyme immediately subsequent to ALA-D, by four- to seven-fold via transfection of cells with PBGD complementary DNA did not alter the activity of ALA-D. However, incubation of cells with various concentrations of succinyl acetone, a potent inhibitor of ALA-D, caused a concomitant decline in both PPIX accumulation and ALA-D activity. These data imply that when cells are exposed to exogenous ALA, ALA-D is an important early-control step in heme/porphyrin biosynthesis and that regulation of PPIX synthesis by this dehydratase may impact the effectiveness of ALA-mediated photosensitization.