Risk of Ocular Exposure to Biologically Effective UV Radiation in Different Geographical Directions

To quantify ocular exposure to solar ultraviolet radiation (UVR) and to assess the risk of eye damage in different geographical directions due to UVR exposure, we used a spectrometer and a manikin to measure horizontal ambient and ocular exposure UVR in different geographical directions at four different locations at the Northern Hemisphere. Describing the relationship of exposure to risk of eye damage requires the availability of UV hazard weighting function. So, we used the UV hazard weighting function (ICNIRP) proposed by International Commission on Non‐Ionizing Radiation Protection to determine the biologically effective UV irradiance (UVBE_eye) and then cumulative effective radiant exposure (H_eye) to shown the risk of eye. We found that in different geographical directions, distributions of ocular exposure to UVR were markedly different from those of horizontal ambient UVR. When the midday maximum SEA > 50°, eye received more UVR from the east and west directions during the morning and evening hours, respectively. However, when the midday maximum SEA < 50°, eye received more UVR from the south direction at noon. The results of this research indicate that the higher risk of eye caused by UVR varies according to the midday maximum SEA corresponding to different geographical direction.     

Solar Ultraviolet Radiation Measurements in One of the Most Populous Cities of the World: Aspects Related to Skin Cancer Cases and Vitamin D Availability

A number of studies published in the scientific literature have shown the relationship between sun exposure and nonmelanoma skin cancer (NMSC) and vitamin D synthesis. However, the paucity of medical data, particularly in developing countries, hampers a global assessment of the impact of sun exposure on NMSC and vitamin D. To improve knowledge on this subject, this paper presents UV index (UVI) measurements performed in São Paulo City (SPC) in the period 2005–2008. It was found that 65% of the UVI measured 2 h around local noon during the summer show very high (8 < UVI < 10) and extreme (UVI > 11) levels according to the World Health Organization (WHO) classification. During the winter, 40% of the measurements around noontime show high or very high levels. In spite of worrisome recent statistics from SPC, showing that NMSCs make up about 28% of over a million of new cases of cancer in 2008, sun protection is not considered a real problem in these urban areas. UV measurements also show that every month of the year UV levels are high enough to ensure vitamin D production in human skin from incidental sun exposure.     

An LC-MS/MS Method for Analysis of Vitamin D Metabolites and C3 Epimers in Mice Serum: Oral Supplementation Compared to UV Irradiation

Introduction: The most common forms of vitamin D in human and mouse serum are vitamin D3 and vitamin D2 and their metabolites. The aim of this study is to determine whether diet and sunlight directly affect the circulating concentrations of vitamin D metabolites in a mouse model. We investigated the serum concentrations of eight vitamin D metabolites—vitamin D (vitamin D3 + vitamin D2), 25OHD (25OHD3 + 25OHD2), 1α25(OH)₂D (1α25(OH)₂D2, and 1α25(OH)₂D3)—including their epimer, 3-epi-25OHD (3-epi-25OHD3 and 3-epi-25OHD2), and a bile acid precursor 7alpha-hydroxy-4-cholesten-3-one (7αC4), which is known to cause interference in liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Method: The LC-MS/MS method was validated according to FDA-US guidelines. The validated method was used for the analysis of mouse serum samples. Forty blood samples from mice were collected and divided into three groups. The first group, the DDD mice, were fed a vitamin D-deficient diet (25 IU VD3/kg of diet) and kept in the dark; the second group, the SDD mice, were maintained on a standard-vitamin D diet (1000 IU VD3) and kept in the dark; and the third group, SDL, were fed a standard-vitamin D diet (1000 IU VD3) but kept on a normal light/dark cycle. LC-MS/MS was used for the efficient separation and quantitation of all the analytes. Results: The validated method showed good linearity and specificity. The intraday and interday precision were both <16%, and the accuracy across the assay range was within 100 ± 15%. The recoveries ranged between 75 and 95%. The stability results showed that vitamin D metabolites are not very stable when exposed to continuous freeze–thaw cycles; the variations in concentrations of vitamin D metabolites ranged between 15 and 60%. The overlapping peaks of vitamin D, its epimers, and its isobar (7αC4) were resolved using chromatographic separation. There were significant differences in the concentrations of all metabolites of vitamin D between the DDD and SDL mice. Between the groups SDD (control) and SDL, a significant difference in the concentrations of 3-epi-25OHD was noted, where C3 epimer was about 30% higher in SDL group while no significant differences were noted in the concentrations of vitamin D, 25OHD, 1α25(OH)₂D, and 7αC4 between SDD and SDL group. Conclusions: A validated method, combined with a simple extraction technique, for the sensitive LC-MS/MS determination of vitamin D metabolites is described here. The method can eliminate the interferences in LC-MS/MS analysis caused by the overlapping epimer and isobar due to them having the same molecular weights as 25OHD. The validated method was applied to mouse serum samples. It was concluded that a standard-vitamin D diet causes an increase in the proportion of all the vitamin D metabolites and C3 epimers and isobar, while UV light has no pronounced effect on the concentrations of the majority of the vitamin D metabolites except 3-epi-25OHD. Further studies are required to confirm this observation in humans and to investigate the biochemical pathways related to vitamin D’s metabolites and their epimers.     

MC1R,Eumelanin and Pheomelanin: Their Role in Determining the Susceptibility to Skin Cancer

Skin pigmentation is due to the accumulation of two types of melanin granules in the keratinocytes. Besides being the most potent blocker of ultraviolet radiation, the role of melanin in photoprotection is complex. This is because one type of melanin called eumelanin is UV absorbent, whereas the other, pheomelanin, is photounstable and may even promote carcinogenesis. Skin hyperpigmentation may be caused by stress or exposure to sunlight, which stimulates the release of α‐melanocyte stimulating hormone (α‐MSH) from damaged keratinocytes. Melanocortin 1 receptor (MC1R) is a key signaling molecule on melanocytes that responds to α‐MSH by inducing expression of enzymes responsible for eumelanin synthesis. Persons with red hair have mutations in the MC1R causing its inactivation; this leads to a paucity of eumelanin production and makes red‐heads more susceptible to skin cancer. Apart from its effects on melanin production, the α‐MSH/MC1R signaling is also a potent anti‐inflammatory pathway and has been shown to promote antimelanoma immunity. This review will focus on the role of MC1R in terms of its regulation of melanogenesis and influence on the immune system with respect to skin cancer susceptibility.     

From UV to NIR: A Full-Spectrum Metal-Free Photocatalyst for Efficient Polymer Synthesis in Aqueous Conditions

Photo-mediation offers unparalleled spatiotemporal control over controlled radical polymerizations (CRP). Photo-induced electron/energy transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization is particularly versatile owing to its oxygen tolerance and wide range of compatible photocatalysts. In recent years, broadband- and near-infrared (NIR)-mediated polymerizations have been of particular interest owing to their potential for solar-driven chemistry and biomedical applications. In this work, we present the first example of a novel photocatalyst for both full broadband- and NIR-mediated CRP in aqueous conditions. Well-defined polymers were synthesized in water under blue, green, red, and NIR light irradiation. Exploiting the oxygen tolerant and aqueous nature of our system, we also report PET-RAFT polymerization at the microliter scale in a mammalian cell culture medium.     

A Simplified Method for the Determination of Labeled Alkane Hydrocarbons in Mammalian Tissue and Blood After Exposure to Radiolabeled Cigarette Smoke

Abstract

A simplified procedure for the determination of ¹⁴C- labeled alkanes in mammalian tissue and blood is proposed. A portion of the ethanolic-KOH digest of the sample is counted in a standard toluene scintillator solution; consequently no secondary scintillator solvent or special tissue solubilizer is required. A wide variety of sample types and sizes, including whole organs, can be handled without homogenization or drying. Accuracy and precision are good. Sensitivity is generally inversely related to sample size.     

New Method for Determining H-Bond Energy: Fluorescence from Neutral Red in Water Compared to Fluorescence from Neutral Red in Benzene

A new method is presented for determining the H-bond energy between a fluorescent solute and water. In the current example the hydrogen-bond energy between neutral red (NR) and water was measured. The H-bond energy was obtained from the temperature dependence of the ratio of the 625 nm fluorescence intensity from NR in water, which increases with increasing temperature, to that of the 530 nm intensity from NR in benzene, which decreases with increasing temperature. The H-bond energy so determined is (10050 ± 60) J-mol⁻¹, which compares favorably with an H-bond E_HB value for pure water of 10170 J-mol⁻¹. Intermolecular hydrogen-bonding between water and NR increases the nonradiative deactivation process of the excited molecule due to fast energy dissipation through the vibrations associated with the hydrogen bonds. Some of the hydrogen bonds are broken with an increase in temperature, resulting in an increase in the number of free NR molecules, thus increasing the fluorescence quantum yield.     

Development and Validation of an HPLC–UV Method for the Determination of Insulin in Rat Plasma: Application to Pharmacokinetic Study

A simple, sensitive high performance liquid chromatographic method with UV detection was developed and validated for determination of insulin in rat plasma, using methyl paraben as an internal standard. Insulin was extracted from plasma by a liquid–liquid extraction with a mixture of dichloromethane and n-hexane (1:1, v/v) followed by an acidic back extraction. Chromatographic separation was achieved isocratically with a Phenomenex® C₁₈ analytical column (150 × 4.6 mm ID, 5 μm) at ambient room temperature. The calibration curves were linear within a concentration range of 0.7–8.4 μg mL^?1 (r ² = 0.9994). The inter-day and intra-day accuracy and precision were ≤3.33 and ≤5.55%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.35 and 0.7 μg mL^?1. The average recovery was 87.86% for insulin and 83.52% for methyl paraben. Insulin containing plasma samples were stable at ?20 °C for 7 days. Validated HPLC method was successfully applied to a pharmacokinetic study of insulin in streptozotocin induced diabetic rats.     

Synthesis of the epoxyquinol dimer RKB-3564 D: utilization of an alkoxysilanol to promote [4 + 4] dimerization

The synthesis of the epoxyquinol dimer RKB-3564 D (3) is reported, employing an alkoxysilanol protecting group to redirect the inherently favored [4 + 2] dimerization of 2H-pyran monomers to a [4 + 4] manifold. Preliminary mechanistic studies indicate that the [4 + 4] dimerization may occur through a stepwise, ionic process.     

Vitamin D: a concise synthesis of the C19 hydroxylated enyne A-ring, an interesting precursor for the preparation of C19 substituted vitamin D analogues

A new C₁₉ hydroxylated enyne 15, as potential A-ring building block of vitamin D analogues, was synthesized in enantiomerically pure form in nine steps from (−)-(S)-limonene. This short synthesis involved ozonolyzis of 1,2-limonene oxide followed by a Criegee rearrangement, epoxide trans diaxial ring opening by lithium acetylide, elimination, epoxidation and syn β-elimination of the resulting homopropargylic oxirane.     

Copper Tetrahydrosalen Complex Encapsulated in Zeolite Y： an Effective Heterogeneous Catalyst for the Oxidation of Cycloalkanes

In the last decade, encapsulation of transition metal complexes in zeolites and related materials has been paid much attention, because this type of materials could serve as functional mimic enzymes, possessing both homogeneous-catalysis and heterogeneous…     

Determining valine side-chain rotamer conformations in proteins from methyl 13C chemical shifts: application to the 360 kDa half-proteasome

A method is presented for determining Val side-chain χ(1) rotamer distributions in proteins based exclusively on measured (13)C(γ1) and (13)C(γ2) chemical shifts. The approach selects an ensemble of 20 χ(1) values, calculates average methyl (13)C(γ1,γ2) chemical shifts via theoretical quantum chemical calculations and maximizes the agreement with the experimentally measured shifts using a genetic algorithm. The methodology is validated with an application involving six proteins for which (13)C(γ) chemical shifts and three-bond methyl-backbone scalar couplings are available. The utility of the methodology is demonstrated with an application to the 360 kDa 'half-proteasome' where the χ(1) rotameric distributions of Val residues are calculated on the basis of chemical shifts. For the most part the χ(1) profiles so obtained compare very well with those generated from the high-resolution (2.3 ?) X-ray structure of the proteasome. Both NMR and X-ray distributions are cross-validated by comparing calculated (1)H-(13)C methyl residual dipolar couplings with measured values, and the level of agreement is at least as good for the NMR derived χ(1) values. Notably, as the resolution of the X-ray data improves (rotamer distributions from 3.4 and 2.3 ? X-ray structures are compared with the NMR data), the agreement with the NMR gets significantly better. This emphasizes the importance of NMR approaches for the study of high molecular weight complexes that can be recalcitrant to high resolution X-ray analysis.     

Freeing the Polarons to Facilitate Charge Transport in BiVO4 from Oxygen Vacancies with an Oxidative 2D Precursor

The BiVO₄ photoelectrochemical (PEC) electrode in tandem with a photovoltaic (PV) cell has shown great potential to become a compact and cost‐efficient device for solar hydrogen generation. However, the PEC part is still facing problems such as the poor charge transport efficiency owing to the drag of oxygen vacancy bound polarons. In the present work, to effectively suppress oxygen vacancy formation, a new route has been developed to synthesize BiVO₄ photoanodes by using a highly oxidative two‐dimensional (2D) precursor, bismuth oxyiodate (BiOIO₃), as an internal oxidant. With the reduced defects, namely the oxygen vacancies, the bound polarons were released, enabling a fast charge transport inside BiVO₄ and doubling the performance in tandem devices based on the oxygen vacancy eliminated BiVO₄. This work is a new avenue for elaborately designing the precursor and breaking the limitation of charge transport for highly efficient PEC‐PV solar fuel devices.     

Benzoic Acid: an Efficient and Rapid Catalyst for the Synthesis of α-Hydroxyl(indolyl)ethanones from Indoles

An efficient method for regioselective Friedel-Crafts alkylations of indole using arylglyoxals in the presence of benzoic acid has been discovered. The reactions proceeded smoothly at room temperature under metalfree conditions and generated the corresponding products in good to excellent yields. This methodology has a broad substrate scope and opens up an interesting and attractive avenue for the synthesis of α-hydroxyl(indolyl)-ethanones.     

Synthesis of optically active cyanohydrins from aromatic ketones: evidence of an increased substrate range and inverted stereoselectivity for the hydroxynitrile lyase from Linum usitatissimum

The synthesis of (R)- and (S)-cyanohydrins from a range of aromatic methyl and ethyl ketones, including the first examples from substituted variants of phenylacetone, benzylacetone and propiophenone, is described. Commercially available hydroxynitrile lyase (HNL) enzymes were used to catalyze the asymmetric addition of cyanide to the ketones, including the first successful application of the flax HNL (LuHNL) to the synthesis of any aromatic (S)-cyanohydrin. Both reaction yields and stereoselectivities were shown to be influenced by the carbon chain length between the ketone and phenyl functional groups, and the type of aromatic substitution present on the starting material. Substrates converted with the greatest degree of productivity and selectivity were phenylacetones with large, electron withdrawing meta-substituents, such as 3-Cl, 3-Br and 3-CF₃ phenylacetones, from which cyanohydrins are formed with 93–99% ee and 61–71% yield.     

Aluminium Nitrate/Silica Sulfuric Acid/Bromide Ion: As an Effective and Catalytic Oxidizing Media for the Selective Oxidation of Sulfides to Sulfoxides

Various types of sulfides are chemoselectively oxidized to the corresponding sulfoxides by treatment of Al(NO₃)₃.9H₂O, silica sulfuric acid and a catalytic amount of NaBr in the presence of wet SiO₂ (50% w/w) in CH₂Cl₂ at room temperature. The catalytic oxidation procedure is very simple and the products are easily isolated in good yields.     

Four‐Component Synthesis of Phosphonium Salts: Application Toward an Alternative Approach to Cross‐Coupling for the Synthesis of Bis‐Heteroarenes

A series of stable phosphonium salts have been synthesized via a novel four‐component reaction of an arene nucleophile, 2‐heteroatom substituted aryl aldehyde, and phosphine in presence of an acid. The phosphonium salts thus obtained were utilized for the synthesis of a variety of bis‐heteroarenes, providing an efficient alternative method to the classical cross‐coupling strategies.     

Synthesis of a precursor for an alumina ceramic reinforced by zirconium dioxide from inorganic compounds in the presence of urea

Samples of a precursor for an alumina ceramic reinforced by zirconium dioxide were synthesized. The samples have a uniform structure and are characterized by high ratios of the tetragonal and monoclinic modifications of ZrO₂, tlm, after a thermal treatment (1250°C). The structure of samples in the system Al₂O₃-ZrO₂ is formed under conditions favorable for deposition of products of hydrolysis of Al(III) ions on the surface of ZrO₂ sol particles in decomposition of urea. The coating of ZrO₂ sol particles by products of hydrolysis of Al(III) salts was confirmed by electrophoresis. The size distribution of particles of the in?dividual ZrO₂ sol was determined by small-angle X-ray scattering. The structure of the products formed in thermal treatment of samples of mixed oxides Al₂O₃-ZrO₂ was characterized by X-ray phase analysis and scanning electron microscopy. The porosity and specific surface area of a thermally treated sample was determined by measuring nitrogen absorption isotherms.     

Choline Chloride–Lactic Acid-Based NADES As an Extraction Medium in a Response Surface Methodology-Optimized Method for the Extraction of Phenolic Compounds from Hazelnut Skin

Deep eutectic solvents (DESs) are promising green solvents for the extraction of compounds from food byproducts. Hazelnut (Corylus avellana L.) is one of the most commonly cultivated tree nuts worldwide. The skin represents one of the major byproducts of the hazelnut industry and accounts for 2.5% of the total hazelnut kernel weight. It is a rich source of phenolic compounds like flavan-3-ols, flavonols, dihydrochalcones, and phenolic acids. In this work, fifteen DESs based on choline chloride and betaine, with different compositions, were studied in order to test their phenolic compounds extraction efficiency through the determination of their total concentration via Folin–Ciocalteu assay. A qualitative analysis of extracted phenolic compounds was assessed by HPLC with UV and MS detection. Using the DES with the best extraction efficiency, a new ultrasound-assisted solid liquid extraction (UA-SLE) method was optimized though the response surface methodology (RSM), taking into account some extraction parameters. Efficient recovery of extracted phenolic compounds was achieved using a 35% water solution of choline chloride and lactic acid (molar ratio 1:2) as an extraction solvent, working at 80 °C and with a solid-to-solvent ratio of 1:25 gmL⁻¹. The optimized conditions made it possible to recover 39% more phenolic compounds compared to a classic organic solvent.