A critical role for dermal mast cells in cis-urocanic acid-induced systemic suppression of contact hypersensitivity responses in mice

Many studies have implicated cis-urocanic acid (cis-UCA) in UVB-induced immunomodulation. The strongest evidence came from studies in mice whereby a cis-UCA antibody blocked UVB-induced suppression of delayed-type hypersensitivity responses. Furthermore, in several studies, the cis-UCA antibody at least partially reversed UVB suppression of contact hypersensitivity responses. Previous reports suggested that cis-UCA was immunomodulatory through its effects on keratinocytes, Langerhans cells, fibroblasts, T lymphocytes, natural killer cells and monocytes/macrophages. As dermal mast cells were recently demonstrated to be critical to UVB-induced systemic suppression of certain delayed-type and contact hypersensitivity responses, we investigated whether they were involved in the processes by which cis-UCA was immunomodulatory. Not only was there a correlation between dermal mast cell prevalence and the degree of susceptibility of different strains of mice to the immunomodulatory effects of cis-UCA, there was also a functional link. Mast cell-depleted Wf/Wf mice were rendered susceptible to immunomodulation by cis-UCA injected subcutaneously only after their dorsal skin had been reconstituted with bone marrow-derived mast cell precursors. These studies suggest that mast cells are critical to the processes by which cis-UCA suppresses systemic contact hypersensitivity responses to the hapten, trinitrochlorobenzene, in mice.     

The effect of suntan parlor exposure on delayed and contact hypersensitivity

Cutaneous and systemic immune function are believed to play an important role in cutaneous carcinogenesis. We therefore sought to determine whether the suntan parlor radiation sources commonly used in the United States cause measurable qualitative suppression of immune function and quantitative alterations in circulating T cell subpopulations. Subjects (n = 22) were recruited and randomly assigned to receive suntan parlor exposures (10 full-body UV exposures over a 2 week period, shielding only the right flexural arm) or no exposure. Baseline circulating T lymphocyte subpopulations (T helper lymphocyte, CD4; T suppressor/cytotoxic lymphocyte, CD8) were measured. Two weeks later (upon completion of UV exposures for those in this group), circulating T cell subpopulations were measured and dinitrochlorobenzene (DNCB) sensitization (in the UV group, on the UV-exposed buttock) was performed. Subsequent DNCB elicitation was performed in a bilateral fashion (in the UV group, on the right UV-shielded and the left UV-exposed upper arm). We found that subjects in the UV group demonstrated localized suppression of contact hypersensitivity sensitization and elicitation and also an increase in circulating CD8 cells when compared to the control group (P < or = 0.05). We conclude that suntan parlor exposures, as typically received in this country, suppress contact hypersensitivity and increase the circulating T suppressor/cytotoxic cell number quantity.     

The dynamic nature of contact angles as measured by atomic force microscopy

Atomic force microscopy appears to be a useful tool for determining the contact angle for small particles. It is shown in this paper that the contact angle of a spherical polyethylene particle changes with the speed of the AFM piezoelectric translator. Such dynamic behavior of the contact angle and other uncertainties such as the position of the three-phase contact on the particle surface during bubble-particle interaction make it difficult to decide whether or not the AFM single-particle contact angle can be used to describe the hydrophobic state of the particle surface.     

The effect of chronic ultraviolet radiation on the human immune system

A single or a limited number of UVR exposures is recognized to suppress cell-mediated immunity in human subjects. The complex pathway leading from the absorption of photons by chromophores in the skin to the generation of T regulatory cells has been, at least partially, elucidated. However, the effect of repeated UV exposures on immune responses and associated mediators is not well studied, particularly to assess whether they lead, first, to the development of photoprotection so that these immune changes are reduced or no longer occur, and, secondly, to the development of photoprotection against the normal downregulation of immunity induced by a high UV dose. For almost all the parameters evaluated in this review--epidermal DNA damage/erythema, urocanic acid, Langerhans and dendritic cells, natural killer cells, macrophages, mast cells, contact and delayed hypersensitivity responses--none, aside from epidermal DNA damage/erythema and macrophage phagocytic activity, show convincing evidence of photoadaptation or, where appropriate, photoprotection. It is concluded that repeatedly irradiating individuals with UVR is likely to continue to result in downregulation of immunity.     

IL-10 does not play a role in cutaneous Photofrin photodynamic therapy-induced suppression of the contact hypersensitivity response.

Photodynamic therapy (PDT) treatment of both malignant and benign skin diseases has proven to be effective, and its use is increasing worldwide. However, preclinical studies using murine models have shown that PDT of the skin inhibits cell-mediated immune reactions, as measured by the suppression of the contact hypersensitivity (CHS) reaction. We have previously demonstrated that PDT enhances IL-10 expression in treated skin, and that the kinetics of induction of IL-10 is similar to the kinetics of suppression of systemic CHS reactions by cutaneous PDT. In the following report we have expanded upon these studies to demonstrate that cutaneous PDT, using Photofrin, induces elevated levels of systemic IL-10 that persist for at least 28 days following treatment. The increase in systemic IL-10 correlates to a prolonged suppression of CHS of at least 28 days following cutaneous PDT. IL-10 has been implicated as the causative agent in the suppression of cell-mediated immune reactions by UVB and transdermal PDT. However, in the studies reported here we demonstrate that the suppression of CHS by cutaneous PDT occurs via an IL-10 independent mechanism, as administration of anti-IL-10 antibodies had no effect on the ability of PDT to induce CHS suppression. These results were further confirmed using IL-10 knockout (KO) mice. Cutaneous PDT of IL-10 KO mice resulted in CHS suppression that was not significantly different from suppression induced in wild-type mice. Thus, it appears as though IL-10 does not play a role in CHS suppression by cutaneous PDT. Suppression of cell-mediated immune reactions by UVB and transdermal PDT is reversible by IL-12, which is critical for the development of these reactions. We show that administration of exogenous IL-12 is also able to reverse CHS suppression induced by cutaneous PDT, suggesting that whereas suppression of cell-mediated immune reactions by UVB, transdermal PDT and cutaneous PDT occurs via different mechanisms, a common regulatory point exists.     

The effect of environment on cystine disruption by ultraviolet light

When cystine is irradiated at pH 1 by 254-nm u.v. the following yields are observed: 4 cystines → 5.2 cysteines + 2.8NH₃. Thus, SH production accounts for only 0.65 of the cystine destruction; further C-S breakage to give alanine or serine is not efficient. The yields for cystine and glutathione destruction are essentially the same at pH 1. However the presence of the glutamic and glycine residues stabilize the cystine in glutathione so that NH₃ is not lost until the peptide bonds are hydrolyzed. Increasing the pH from 1 to 8.6 increases the yield of cystine destruction in glutathione by 50 per cent. The yield of cystine destruction is greater in both compounds when O₂ is present during irradiation (e. g. the cysteic acid yield in glutathione is increased by 50 times). The overall production of SH varies by a factor of 2 in the four proteins-insulin, RNase, trypsin and lysozyme. The present data further support the earlier observation that radiation damage is quite non-random in RNase: at least two and perhaps three of the four constituent cystines must be disrupted before activity is lost: i.e. the most radiosensitive cystines are not critical for enzymic activity. Similarly, in both trypsin and lysozyme the integrity of the most radiosensitive cystines also does not appear to be critical for the retention of enzymic potential. In insulin, however, all three cystines appear to be crucial for activity and to have approximately equal radiosensitivities. These differences in sensitivity of cystines in different proteins must depend specifically upon energy transfer and/or chemical interactions between the chromophoric groups. If yields are calculated on the basis of those quanta absorbed only in the cystines, values about 5 to 8 times greater than those in the model compounds cystine and oxixized glutathione are obtained. The yields of cystine destruction are much higher in those protiens which contain trypotophan.     

A re-evaluation of hydroxylammonium acetate as a carbonyl reagent — the effect of dielectric constant change on titration end-points

The determination of carbonyl groups with hydroxylammonium acetate in acetic acid has been re-examined. The reaction of hydroxylammonium acetate with acetic acid has been found to yield non-basic products, first acethydroxamic acid and eventually diacetylhydroxylamine, which do not interfere with the analyses. Calculations based on kinetics show that loss of the reagent is negligible in most cases, and in the extreme, involves only 0.9% of the amount originally present. Analyses in acetic acid media throughout are compared with those in which the titrations were conducted in benzene-acetic acid or carbon tetrachloride-acetic acid mixtures whose compositions were chosen to yield the most favorable titrations. The slopes of the titration curves were uniformly improved in the systems containing inert solvents, as predicted by consideration of the effect of dielectric constant change. Analytical precision was slightly improved except for aromatic aldehydes. Neither inert solvent system seemed superior to the other. The undesirable effect of small amounts of water is discussed.     

Prevention of UV radiation-induced premature skin aging in hairless mice by the novel compound Melanocin A

Repetitive exposure of the skin to UV radiation induces various harmful changes, such as thickening, wrinkle formation, inflammation and carcinogenesis. A variety of natural compounds and synthetic compounds have been studied to determine whether they can prevent UV-induced harmful effects. In this study, we investigated the effect of a novel compound, Melanocin A, which was isolated from Eupenicillium shearii F80695, on UV-induced premature skin aging. First, we studied the effect of Melanocin A on UV-induced matrix metalloproteinase (MMP)-9 expression in an immortalized human keratinocyte cell line, HaCaT, in vitro. Acute UV irradiation induced MMP-9 expression at both the mRNA and protein levels and Melanocin A suppressed this expression in a dose-dependent manner. We then investigated the effect of Melanocin A on UV-induced skin changes in hairless mice in vivo. Chronic exposure of hairless mouse dorsal skin to UV increased skin thickness and induced wrinkle formation and the gelatinase activities of MMP-2 and MMP-9. Moreover, Melanocin A significantly suppressed UV-induced morphologic skin changes and MMP-2 and MMP-9 expression. Taken together, these results show that Melanocin A can prevent the harmful effects of UV that lead to skin aging. Therefore, we suggest that Melanocin A should be viewed as a potential therapeutic agent for preventing and/or treating premature skin aging.     

The effect of calcining conditions on the rehydration of dead burnt magnesium oxide using magnesium acetate as a hydrating agent

Summary Magnesium oxide was produced through calcination of magnesite ore. A rehydration percentage of MgO to Mg(OH)₂ of higher than 60% is obtained using calcination temperatures of 1000°C and below. At these temperatures medium reactive MgO was formed. The extend to which dead burnt MgO (obtained after calcination at 1200°C and higher) may be rehydrated is dependent on the calcination time, but even after 1 h and using magnesium acetate as a hydrating agent only 40% of the initial product has rehydrated to Mg(OH)₂. After 4 and more hours of calcinations at 1200°C, a maximum of approximately 14% of the initial MgO is rehydrated back to Mg(OH)₂. Thermogravimetric analysis was performed on the various compounds to determine the amounts of Mg(OH)₂ that formed.     

The effect of irradiation by ultraviolet light on ureido‐pyrimidinone based biomaterials

Supramolecular polymers based on ureido‐pyrimidinone (UPy) represent a promising class of biocompatible materials for medical applications. Here, the chemical modification effect of UV irradiation, used to sterilize these materials, is studied. Besides anticipated crosslinking effects, UV irradiation causes telechelic UPy‐polymers to become fluorescent. UPy‐model compounds confirm a relation between UV‐induced changes and the UPy‐moiety. UV‐induced fluorescence and IR‐spectral changes are (partially) reversible by heat and/or solvent treatment. The results indicate the presence of at least two distinct UV‐induced molecular species. UPy‐model compounds with specific tautomeric forms directly relate fluorescence to UPy‐enol tautomers. Photo‐enolization is hypothesized to occur via an excited‐state intermolecular double proton transfer. Changes in UPy‐tautomeric equilibrium and crosslinking are factors that influence the dynamics of UPy‐based materials. Identification and understanding of such factors will aid in the successful application of these materials, for example as biomaterial in tissue engineering applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 81–90     

The effect of heating on background and radiation-induced EPR signals in tooth enamel

The presented study is a continuation of our work performed during participation in the Third International Intercomparison on EPR Tooth Dosimetry. During the process of samples preparation, all 22 enamel samples were accidentally exposed for about 30 min to 150 degrees C temperature. This considerably affected shape of their EPR spectra mainly due to substantial increase in the background signal, which approximately doubled its contribution to the spectra. These effects were studied closer under controlled conditions of the delivered dose and heating temperature using another enamel samples. The observed changes in the spectra shape partially faded within a few days after heating. The heating resulted also in a noticeable generation of a spectral component similar to the dosimetric signal induced in enamel by radiation. The temperature-induced dosimetric component in EPR spectra of the heated samples remained constant for 32 days. Deviations in calculated contributions of the dosimetric signal into total EPR spectra of irradiated sample varied from -12 to +15% of its initial contribution in the non-heated enamel, depending on type of the background spectrum applied in numerical processing of the spectra.     

Studies on fluorescein-V The absorbance of fluorescein in the ultraviolet, as a function of pH

The ultraviolet absorption spectum of an aqueous solution of highly-purified yellow fluorescein at ionic strength 0.10 has been measured at various pH values in the range from 0.15 to 8.70. The maxima at 227, 249 and 295 nm change little with pH, but the maximum found at 437 nm in acid medium changes greatly in absorbance and position on addition of alkali, resolving first into two maxima, at 455 and 475 nm, and finally becoming a single large maximum (at pH 8) at 490 nm. A unique feature of the absorption at 437 nm is that all four prototropic forms of fluorescein, H(3)Fl(+), H(2)Fl, HFl(-) and Fl(2-), absorb at this wavelength. The total absorbance at this wavelength first falls rapidly as the pH rises from 0.15, reaching a minimum at pH 3.63, then increases to a maximum at pH 5.3, and finally falls to steady value at pH > 8.0. The absorbance as a function of pH is defined by seven constants: three dissociation constants (K(H(3)Fl) = 6.61 x 10(-3), K(H(2)Fl) = 3.98 x 10(-5), K(HFl) = 4.36 x 10(-10)) and four molar absorptivities ((H(3)Fl) = 4.94 x 10(-4), (H(2)Fl) = 1.20(5) x 10(4), (HFl) = 2.16 x 10(4) and (Fl) = 7.61 x 10(3) 1.mole(-1).cm(-1)). Solutions of yellow fluorescein in water undergo rapid deterioration on exposure to daylight or fluorescent lighting but are stable in the dark.     

The effect of ultraviolet light on RNA metabolism in bromouracil deoxyriboside-grown HeLa cells

Abstract— The presence of 5-bromouracil deoxyriboside (BrUdR) in the DNA of HeLa cells has profound effects on RNA metabolism after u.v. irradiation. In normally grown cells 200 ergs/mm² depresses RNA synthesis by about 30 per cent while in BrUdR-grown cells the same exposure to u.v. depresses RNA synthesis by 95 per cent. When BrUdR-grown cells are u.v. -irradiated after being labeled with ³H-uridine, the normal autoradiographic pattern, where label shifts from nucleus to cytoplasm, fails to occur. Also, in lieu of the increase in RNA specific activity that is observed in unirradiated cells for a few hours after 20-min pulse-labeling, there occurs a constant decrease in specific activity after the irradiation.     

Electrically induced anisotropy in a colloidal dispersion of nanospheres as measured by electric birefringence

Electrically induced birefringence experiments were performed on dispersions consisting of sulfate latex nanospheres of two different sizes and charges dispersed in an electrolyte solution, at various ionic strengths. The induced birefringence was found to have an important contribution increasing as a quadratic power law of the volume fraction of the spheres. This shows that interparticle interactions play a role in the observed birefringence. The data were analyzed, using a theory from Hafkenscheid and Vlieger [Physica 75 (1974) 57], in terms of the changes of the interparticle separations in the directions parallel and perpendicular to the applied electric field.     

A study of vitamin A as a probe in critical micelle concentration determinations of surfactants

The effects of the heteroatom donor on the complexation of various metal ions by macrocyclic polyethers were qualitatively examined by application of the ligand exchange technique in a quadruple ion trap mass spectrometer. The metal ions, including K⁺, Cs⁺, Al⁺, Mg⁺, Cu⁺ and Ni⁺, were generated by laser desorption and allowed to react with 12-crown-4 and its nitrogen and sulfur analogs, cyclen and 1,4,7,10-tetrathiacyclododecane. The orders of gas-phase basicities were established as a comparison. The relative K⁺ and Cs⁺ binding affinities of 12-crown-4 are greatest, whereas cyclen has the highest binding affinity for all the other metal ions and also the highest gas-phase basicity.     

Oleuropein prevents the progression of steatohepatitis to hepatic fibrosis induced by a high-fat diet in mice

Nonalcoholic steatohepatitis (NASH) is characterized by hepatocyte injury and inflammatory cell infiltration, which has been linked to peripheral insulin resistance and increased levels of triglycerides in the liver. The purposes of this study were to establish a mouse model of NASH by feeding mice a 60% high-fat diet (HFD) and to demonstrate the anti-fibrotic effects of oleuropein, which has been shown to have anti-oxidant and anti-inflammatory properties, in this HFD-induced mouse model of NASH. C57BL/6 mice were divided into three groups: a regular diet group (Chow), a HFD group and an oleuropein-supplemented HFD group (OSD), which was fed a 0.05% OSD for 6 months. The effects of oleuropein in this model were evaluated using biochemical, histological and molecular markers. The expression levels of alpha-smooth muscle actin (α-SMA)and collagen type I in the HFD and OSD groups were evaluated using real-time PCR and western blotting. The body weight, biochemical marker levels, nonalcoholic fatty liver disease activity score, homeostasis model of assessment-insulin resistance (HOMA-IR) and leptin levels observed in the HFD group at 9 and 12 months were higher than those observed in the Chow group. The HOMA-IR and leptin levels in the OSD group were decreased compared with the HFD group. In addition, α-SMA and collagen type I expression were decreased by oleuropein treatment. We established a NASH model induced by HFD and demonstrated that this model exhibits the histopathological features of NASH progressing to fibrosis. Our results suggest that oleuropein may be pharmacologically useful in preventing the progression of steatohepatitis and fibrosis and may be a promising agent for the treatment of NASH in humans.     

The effect of vitamin E on micellization of sodium pentadecylsulfonate in ethanol solutions

The effect of vitamin E on micellization of anionic surfactant sodium pentadecylsulfonate in ethanol solutions was studied. The thermodynamic parameters of micellization and the free energy of transfer of vitamin E from ethanol to surfactant-ethanol solution were determined. It was established that, with an increase of temperature and vitamin E concentration, micellization of sodium pentadecylsulfonate in ethanol solutions was inhibited.     

Rapid analysis of 14 ultraviolet absorbents in plastic food contact materials by supercritical fluid chromatography on Sub-2-micron particles

Abstract

A rapid and reliable method based on supercritical fluid chromatography (SFC) technology was established for the analysis of 14 ultraviolet (UV) absorbents in plastic food contact materials. The separation was optimized by employing different chromatographic conditions including stationary phases, organic modifiers, column temperatures and back pressures to achieve appropriate selectivity and resolution. The 14 UV absorbents were analyzed within 4.5?min on the sub-2-micron particles column (ACQUTY UPC² HSS C18?SB) via gradient elution with methanol as the organic modifier. The calibrations were carried out in the concentration range of 0.1–50.0?mg/L (except for UV-329 and UV-320 were 0.2–50.0?mg/L, UV-360 was 0.3–50.0?mg/L), and excellent linearity was observed with correlation coefficients (R²) greater than 0.99. The limits of quantification (LOQ) were in the range of 0.10–0.30?µg/g. The recoveries for accuracy were ranged from 90.4 to 114.1%, and the relative standard deviation (RSD) for repeatability was between 0.67 and 7.23%, respectively. The established method was successfully applied for the analysis of UV absorbents in five plastic food contact materials samples. The SFC method developed in this study can provide an alternative route for routine analysis of UV absorbents in the future.