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Hydrostannylation of allenoate 1 with halogenotin hydride (Bu2SnClH) was developed to give allylic stannane (I), which then could react with aldehyde 2.

We report a 4-t-butylbenzyl derivatization for the analysis of carboxylic acids by GC–MS (EI). Carboxylic acids were analyzed as a 4-t-butylbenzyl ester after the derivatization with 4-t-butylbenzyl bromide. On the mass spectra of 4-t-butylbenzyl ester, [M-15]+ ions were observed with high intensity. These ions were tertiary benzyl cations generated by the elimination of a methyl radical from molecular ions. After optimization of the 4-t-butylbenzyl derivatization conditions using microwave reactor, we established a method for the determination of the carboxylic acids in water samples. The method showed good sensitivity and good reproducibility, and was successfully applied to the analysis of rain water samples.

In this study, in situ catalytically generated allylic indium from 1,3 dienes and InCl2H was developed for use in the allylation of ketones. This protocol resulted in the unprecedented establishment of a successive combining of quaternary C–C bonds, which could then be applied to many types of ketones. Other branched 1,3 dienes and vinyl cyclopropanes, could also be coupled with ketones in a reaction where CuH would not be applicable.

Background Actinomyces oris is an early colonizer and has two types of fimbriae on its cell surface, type 1 fimbriae (FimP and FimQ) and type 2 fimbriae (FimA and FimB), which contribute to the attachment and coaggregation with other bacteria and the formation of biofilm on the tooth surface, respectively. Short-chain fatty acids (SCFAs) are metabolic products of oral bacteria including A. oris and regulate pH in dental plaques. To clarify the relationship between SCFAs and fimbrillins, effects of SCFAs on the initial attachment and colonization (INAC) assay using A. oris wild type and fimbriae mutants was investigated. INAC assays using A. oris MG1 strain cells were performed with SCFAs (acetic, butyric, propionic, valeric and lactic acids) or a mixture of them on human saliva-coated 6-well plates incubated in TSB with 0.25% sucrose for 1 h. The INAC was assessed by staining live and dead cells that were visualized with a confocal microscope. Results Among the SCFAs, acetic, butyric and propionic acids and a mixture of acetic, butyric and propionic acids induced the type 1 and type 2 fimbriae-dependent and independent INAC by live A. oris, but these cells did not interact with streptococci. The main effects might be dependent on the levels of the non-ionized acid forms of the SCFAs in acidic stress conditions. GroEL was also found to be a contributor to the FimA-independent INAC by live A. oris cells stimulated with non-ionized acid. Conclusion SCFAs affect the INAC-associated activities of the A. oris fimbrillins and non-fimbrillins during ionized and non-ionized acid formations in the form of co-culturing with other bacteria in the dental plaque but not impact the interaction of A. oris with streptococci.

We previously reported a constant ratio of the benzothiazole pheomelanin marker thiazole-2,4,5-tricarboxylic acid (TTCA) to the eumelanin marker pyrrole-2,3,5-tricarboxylic acid (PTCA) in eumelanic, black human hair. A constant level (20%-25%) of benzothiazole-type pheomelanin was recently demonstrated in human skin with varying concentrations of melanin. Therefore, in this study, we aimed to investigate the origin of pheomelanin markers in black to brown human hair by developing a method to remove protein components from hair by heating with 6 M HCl at 110°C for 16 hr. For comparison, synthetic melanins were prepared by oxidizing mixtures of varying ratios of dopa and cysteine with tyrosinase. Hair melanins and synthetic melanins were subjected to acid hydrolysis followed by alkaline H2 O2 oxidation. The results show that the hydrolysis leads to decarboxylation of the 5,6-di-hydroxyindole-2-carboxylic acid moiety in eumelanin and the benzothiazole moiety in pheomelanin and that eumelanic human hair contains 11%-17% benzothiazole-type pheomelanin.

Millimeter-wave wireless communications in a high-level information society have been expanding in terms of high-density data transfer and radar for pre-crash safety systems. α-wollastonite (CaSiO 3 ) based and SrSiO 3 based solid solutions (s.s.) in the CaSiO 3 -SrSiO 3 eutectic binary system are expected as millimeter-wave dielectrics because of low dielectric constant as described in a previous paper. In this paper, crystal structures of SrSiO 3 and Ca 0.2 Sr 0.8 SiO 3 compounds are analyzed by Rietveld method using X-ray powder diffraction (XRPD) patterns obtained at the PF-KEK, Tsukuba, Japan. Covalencies of Si O bonds are calculated through the bond strength obtained by the bond length, which at x = 0.8 were higher than that of at x = 1 as (Ca 1- x Sr x )SiO 3 . The lowest dielectric constant ( e r ) and highest Qf value at x = 0.8 with e r = 6.62, Qf = 66,700 GHz and τ f = –40 ppm/°C were explained by the covalencies.

Summary The oral bacterium Streptococcus mutans is the principal agent in the development of dental caries. Biofilm formation by S. mutans requires bacterial attachment, aggregation, and glucan formation on the tooth surface under sucrose supplementation conditions. Our previous microarray analysis of clinical strains identified 74 genes in S. mutans that were related to biofilm morphology; however, the roles of almost all of these genes in biofilm formation are poorly understood. We investigated the effects of 21 genes randomly selected from our previous study regarding S. mutans biofilm formation, regulation by the complement pathway, and responses to competence-stimulating peptide. Eight competence-stimulating peptide-dependent genes were identified, and their roles in biofilm formation and aggregation were examined by mutational analyses of the S. mutansUA159 strain. Of these eight genes, the inactivation of the putative hemolysin III family SMU.940 gene of S. mutansUA159 promoted rapid dextran-dependent aggregation and biofilm formation in tryptic soy broth without dextrose (TSB) with 0.25% glucose and slightly reduced biofilm formation in TSB with 0.25% sucrose. The SMU.940 mutant showed higher expression of GbpC and gbpC gene than wild-type. GbpC is known to be involved in the dextran-dependent aggregation of S. mutans. An SMU.940-gbpC double mutant strain was constructed in the SMU.940 mutant background. The gbpC mutation completely abolished the dextran-dependent aggregation of the SMU.940 mutant. In addition, the aggregation of the mutant was abrogated by dextranase. These findings suggest that SMU.940 controls GbpC expression, and contributes to the regulation of dextran-dependent aggregation and biofilm formation.

Vascularization of reconstructed tissues is one of the remaining hurdles to be considered to improve both the functionality and viability of skin grafts and the relevance of in vitro applications. Our study, therefore, sought to develop a perfusable vascularized full-thickness skin equivalent that comprises a more complex blood vasculature compared to existing models. We combined molding, auto-assembly and microfluidics techniques in order to create a vascularized skin equivalent representing (a) a differentiated epidermis with a physiological organization and correctly expressing K14, K10, Involucrin, TGM1 and Filaggrin, (b) three perfusable vascular channels with angiogenic sprouts stained with VE-Caderin and Collagen IV, (c) an adjacent microvascular network created via vasculogenesis and connected to the sprouting macrovessels. Histological analysis and immunostaining of CD31, Collagen IV, Perlecan and Laminin proved the integrity of vascular constructs. In order to validate the vascularized skin potential of topical and systemic applications, caffeine and minoxidil, two compounds with different chemical properties, were topically applied to measure skin permeability and benzo[a]pyrene pollutant was systemically applied to evaluate systemic delivery. Our results demonstrated that perfusion of skin reconstructs and the presence of a complex vascular plexus resulted in a more predictive and reliable model to assess respectively topical and systemic applications. This model is therefore aimed at furthering drug discovery and improving clinical translation in dermatology.

Efficient conversion of α-mercapto ketones 1 with activated alkenes 2 into S-heterocycles was developed with Sn(Oct)2-2MeOH acting as a catalyst. Two types of products, dihydrothiophene 3 and thiolane 4, were obtained. The selectivity of the products was dependent on the reaction temperature and on the rearrangement of the S-heterocycles from 3 to 4 under heating conditions. The dihydrothiophenes 3 were transformed into useful thiolactones 6-8 and thiophene 9.

In this study

Organic dyes are an attractive alternative to the use of transition-metal complexes in photoredox catalysis. Herein, we report an inexpensive organic dye (eosin Y)-catalyzed radical coupling of α-bromocarbonyl compounds with allyltrifluoroborates under visible light irradiation. This reaction was accelerated by either Bu4NF or CsF. Based on mechanistic studies, the cation exchange between potassium allyltrifluoroborate and Bu4NF proceeded to generate KF. The generated KF or CsF acts as a Lewis acid to promote a single electron transfer (SET) from eosin Y to α-halocarbonyls. The protocol was applied to bromoesters, bromoketones, and bromoamides to give the coupling products in high yields.

The catalytic synthesis of γ-butyrolactams was established via [3 + 2]-cycloaddition of cyclopropanes with isocyanates. An organotin iodide ate complex, MgBr(+)[Bu2SnBrI2](-), was employed as an effective catalyst. Simple cyclopropanes that lack aryl or vinyl substituents were useful precursors. Even acyl cyclopropanes were applicable. The hybrid characteristics of a tin complex, acidic MgBr(+) with nucleophilic tin iodide, was responsible for the catalytic reaction.

In this study, the Bu2SnIH-catalyzed direct coupling of 1,3-dienes with aldehydes was developed. This reaction could be suitable for coupling without the use of transition-metal catalysts. Many types of aldehydes were applied to this reaction. The addition of MeOH promoted the catalytic cycle.

To identify potential regulators of normal human melanocyte behaviour, we have developed an in vitro human melanocyte migration assay, using the optically accessible, real-time cell motility assay device TAXIScan. Coating of the glass surface with an extracellular matrix that served as scaffolding molecule was essential to demonstrate efficient melanocyte migration. Among several chemokines tested, stromal cell-derived factor (SDF)-1α/CXCL12 was the most effective driver of human normal skin melanocytes. Incubation of melanocytes with α-melanocyte-stimulating hormone (MSH) before the assay specifically enhanced CXCR4 expression and consequently chemotaxis towards SDF-1α/CXCL12. These results suggest that α-MSH acts on melanocytes to produce melanin as well as stimulates the cells to migrate to the site where they work through CXCR4 up-regulation, which is a new dynamic mode of action of α-MSH on melanocyte physiology.

Benzoxaboroles are a class of five-membered hemiboronic acids that recently attracted significant attention as a new pharmacophore on account of their unique structural and physicochemical properties and their ability to interact selectively with biomolecules. Their structural behavior in water and its effect on their physiological properties remain unclear, especially the question of dynamic hydrolytic equilibrium of the oxaborole ring. Herein, we used NMR spectroscopy, in mixed aqueous-organic solvent, to confirm the strong preference for the closed form of benzoxaborole and its six- and seven-membered homologues over the open boronic acid form. Only with the eight-membered homologue does the cyclic form become unfavorable. Using dynamic VT-NMR studies with designed probe compound 20, we demonstrate that the oxaborole ring undergoes rapid hydrolytic ring closing–opening at ambient temperature at a rate of >100 Hz via a mechanism featuring rate-limiting proton-transfer steps. This knowledge can help prov...

Organic dyes are an attractive alternative to the use of transition-metal complexes in photoredox catalysis. Herein, we report an inexpensive organic dye (eosin Y)-catalyzed radical coupling of α-bromocarbonyl compounds with allyltrifluoroborates under visible light irradiation. This reaction was accelerated by either Bu4NF or CsF. Based on mechanistic studies, the cation exchange between potassium allyltrifluoroborate and Bu4NF proceeded to generate KF. The generated KF or CsF acts as a Lewis acid to promote a single electron transfer (SET) from eosin Y to α-halocarbonyls. The protocol was applied to bromoesters, bromoketones, and bromoamides to give the coupling products in high yields.

A tin-catalyzed reaction of α-hydroxy ketones with 1,1-dicyanoalkenes produced 2-amino-4,5-dihydrofuran-3-nitriles. In the catalytic reaction, tin enolates were generated from α-hydroxy ketones as active catalytic species. The highly basic ability of the Sn-O bonds played an important role in the reactions. This tin-catalyzed reaction was highly atom-economical and required no other metal reagents.

A coupling between various alkynylstannanes with α-iodo esters was catalyzed by GaBr3 under UV irradiation conditions, for which a catalytic amount of GaBr3 was essential, and a radical coupling wi...

Melasma is a commonly acquired hyperpigmentary disorder of the face, but its pathogenesis is poorly understood and its treatment remains challenging. We conducted a comparative histological study on lesional and perilesional normal skin to clarify the histological nature of melasma. Significantly, higher amounts of melanin and of melanogenesis-associated proteins were observed in the epidermis of lesional skin, and the mRNA level of tyrosinase-related protein 1 was higher in lesional skin, indicating regulation at the mRNA level. However, melanocyte numbers were comparable between lesional and perilesional skin. A transcriptomic study was undertaken to identify genes involved in the pathology of melasma. A total of 279 genes were found to be differentially expressed in lesional and perilesional skin. As was expected, the mRNA levels of a number of known melanogenesis-associated genes, such as tyrosinase, were found to be elevated in lesional skin. Bioinformatics analysis revealed that the most lipid metabolism-associated genes were downregulated in lesional skin, and this finding was supported by an impaired barrier function in melasma. Interestingly, a subset of Wnt signaling modulators, including Wnt inhibitory factor 1, secreted frizzled-related protein 2, and Wnt5a, were also found to be upregulated in lesional skin. Immunohistochemistry confirmed the higher expression of these factors in melasma lesions.

The radical coupling of α- or β-iodo phosphorus compounds such as iodo phosphonate, iodo phosphane oxide, and iodo phosphonothioate with butenylindium species, prepared by transmetalation between a (cyclopropylmethyl)stannane and InBr3, afforded the corresponding cyclopropylmethylated products. The radical reaction was initiated by the radical species generated from butenylindium assisted by a small amount of oxygen. Butenylindium works not only as a cyclopropylmethylating reagent, but also as a radical initiator. For successful coupling, a tin/indium transmetalation was used, where it was important for the tin halide by-product to be inert to the reaction system. In addition, the transmetalation of a (cyclopropylmethyl)stannane and InBr3 provided the dibutenylindium bromide as a single product, which smoothly coupled with the unstable phosphonyl radical species from the iodo phosphorus compound. A photochemical method (UV irradiation) was also applied and accelerated the coupling reaction. The cyclopropylmethylated phosphonate produced was a good intermediate in the Horner–Wadsworth–Emmons reaction and gave functionalized olefins bearing the cyclopropane moiety.

In the synthesis of five-membered heterocycles by the annulation of epoxides with heterocumulenes such as carbon dioxide and isocyanates, we developed the indium-tin catalytic system and synthesized various cyclic adducts including novel types products under mild reaction conditions.

Melasma is a frequent pigmentary disorder caused by abnormal melanin deposits in the skin. In vivo reflectance confocal microscopy (RCM) is a repetitive imaging tool that provides real-time images of the skin at nearly histological resolution. As melanin is the strongest endogenous contrast in human skin, pigmentary disorders are the most suitable candidates for RCM examination but RCM features of melasma have never been reported. This study investigates the pilot use of RCM in melasma to provide a set of well-described morphological criteria with histological correlations. RCM images were acquired from melasma skin and compared to adjacent control skin in 26 patients. Skin biopsies were obtained from eight patients. In the epidermis, RCM showed in all patients a significant increase in hyperrefractile cobblestoning cells. These cells corresponded to hyperpigmented basal keratinocytes in histology. In six patients, dendritic cells corresponding to activated melanocytes were also found in the epidermis. In the dermis, RCM identified in nine patients plump bright cells corresponding to melanophages. Interestingly, for a given patient, the topographic distribution of melanophages in melasma lesions was very heterogeneous. RCM also showed a significant increase in solar elastosis and blood vessels in the dermis. RCM is a non-invasive technique that detects pigmentary changes in melasma at a cellular level resolution. Therefore, RCM provides an innovative way to classify melasma by pigment changes.

We conducted the welding experiment using three kinds of test piece, actual size, diaphragm and butt joint. Then, we examined the influence on strength, cooling time and carbon equivalent of weld metal by welding conditions on the different test pieces. We calculated an estimate of cooling time and chemical components. Consequently, we concluded that the strength of weld metal can be estimated by heat input, interpass temperature, carbon equivarent of welding wire and shape of test piece.

A tin-catalyzed reaction of α-hydroxy ketones with 1,1-dicyanoalkenes produced 2-amino-4,5-dihydrofuran-3-nitriles. In the catalytic reaction, tin enolates were generated from α-hydroxy ketones as active catalytic species. The highly basic ability of the Sn-O bonds played an important role in the reactions. This tin-catalyzed reaction was highly atom-economical and required no other metal reagents.

The synthesis of γ-butyrolactams via [3 + 2]-cycloaddition of cyclopropanes with isocyanates is described.

A coupling between various alkynylstannanes with α-iodo esters was catalyzed by GaBr3 under UV irradiation conditions, for which a catalytic amount of GaBr3 was essential, and a radical coupling wi...

In this study, we have demonstrated the presence of melanin-concentrating hormone (MCH) and melanin-concentrating hormone receptor (MCHR1) transcripts in human skin. Sequence analysis confirmed that the transcripts of both genes were identical to those previously found in human brain. In culture, endothelial cells showed pro-MCH expression whereas no signal was found in keratinocytes, melanocytes, and fibroblasts. MCHR1 expression was restricted to melanocytes and melanoma cells. Stimulation of cultured human melanocytes with MCH reduced the alpha-MSH-induced increase in cAMP production. Furthermore, the melanogenic actions of alpha-MSH were inhibited by MCH. We propose that the MCH/MCHR1 signalling system is present in human skin and may have a role with the melanocortins in regulating the melanocyte.

Various propargyl ethers are synthesized using in situ generated Zn(OMe)Cl or Zn(OEt)Cl, resp., as catalyst.

The cloning and characterization of the human melanocortin-1 receptor (MC1R) and the demonstration that normal human melanocytes respond to the melanocortins, α-melanocyte stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH), with increased proliferation and eumelanogenesis had put an end to a long-standing controversy about the role of melanocortins in regulating human cutaneous pigmentation. We have shown that α-MSH and ACTH bind the human MC1R with equal affinity, and are equipotent in their mitogenic and melanogenic effects on human melanocytes. We also showed that the activation of the MC1R is important for the melanogenic response of human melanocytes to ultraviolet radiation (UVR). The MC1R is also the principal mediator of the inhibitory effects of agouti signaling protein (ASP) on melanogenesis. Expression of the MC1R is subject to regulation by its own ligands α-MSH and ACTH, as well as by UVR and endothelin-1. Recent studies that we conducted on the expression of MC1R variants by human melanocytes and the implications of these variants on the function of the MC1R revealed the following. Human melanocytes homozygous for Arg160Trp mutation in the MC1R demonstrated a significantly reduced response to α-MSH. Also, this culture responded poorly to ASP and exhibited an exaggerated cytotoxic response to UVR. Another culture, which was homozygous for Val92Met mutation in the MC1R, demonstrated a normal response to α-MSH. Heterozygous mutations that are frequently expressed in various melanocyte cultures did not disrupt MC1R function. These results begin to elucidate the significance of MC1R variants in the function of the receptor. Our data emphasize the significance of a normally functioning MC1R in the response of melanocytes to melanocortins, ASP, and UVR.

In mouse follicular melanocytes, the switch between eumelanin and pheomelanin synthesis is regulated by the extension locus, which encodes the melanocortin-1 receptor (MC1R) and the agouti locus, which encodes a novel paracrine-signaling molecule that inhibits binding of melanocortins to the MC1R. Human melanocytes express the MC1R and respond to melanotropins with increased proliferation and eumelanogenesis, but a potential role for the human homolog of agouti-signaling protein, ASIP, in human pigmentation has not been investigated. Here we report that ASIP blocked the binding of alpha-melanocyte-stimulating hormone (alpha-MSH) to the MC1R and inhibited the effects of alpha-MSH on human melanocytes. Treatment of human melanocytes with 1 nM-10 nM recombinant mouse or human ASIP blocked the stimulatory effects of alpha-MSH on cAMP accumulation, tyrosinase activity, and cell proliferation. In the absence of exogenous alpha-MSH, ASIP inhibited basal levels of tyrosinase activity and cell proliferation and reduced the level of immunoreactive tyrosinase-related protein-1 (TRP-1) without significantly altering the level of immunoreactive tyrosinase. In addition, ASIP blocked the stimulatory effects of forskolin or dibutyryl cAMP, agents that act downstream from the MC1R, on tyrosinase activity and cell proliferation. These results demonstrate that the functional relationship between the agouti and MC1R gene products is similar in mice and humans and suggest a potential physiologic role for ASIP in regulation of human pigmentation.

The first catalytic radical coupling of iodomethylphosphorus compounds was accomplished with allyl-, alkenyl-, and allenylstannanes under UV irradiation in the presence of an indium(III) halide catalyst, for which a transmetalated allylic indium species was confirmed to be an active radical species.

The first catalytic radical coupling of iodomethylphosphorus compounds was accomplished with allyl-, alkenyl-, and allenylstannanes under UV irradiation in the presence of an indium(III) halide catalyst, for which a transmetalated allylic indium species was confirmed to be an active radical species.

The butenylindium species generated by transmetalation between stannane (I) and InBr3 reacts with α- or β-iodo phosphorus compounds (II) or (IV) either by thermal heating or under UV irradiation to give the desired cyclopropylalkylphosphorus products.

Melasma is a frequent pigmentary disorder caused by abnormal melanin deposits in the skin. In vivo reflectance confocal microscopy (RCM) is a repetitive imaging tool that provides real-time images of the skin at nearly histological resolution. As melanin is the strongest endogenous contrast in human skin, pigmentary disorders are the most suitable candidates for RCM examination but RCM features of melasma have never been reported. This study investigates the pilot use of RCM in melasma to provide a set of well-described morphological criteria with histological correlations. RCM images were acquired from melasma skin and compared to adjacent control skin in 26 patients. Skin biopsies were obtained from eight patients. In the epidermis, RCM showed in all patients a significant increase in hyperrefractile cobblestoning cells. These cells corresponded to hyperpigmented basal keratinocytes in histology. In six patients, dendritic cells corresponding to activated melanocytes were also found in the epidermis. In the dermis, RCM identified in nine patients plump bright cells corresponding to melanophages. Interestingly, for a given patient, the topographic distribution of melanophages in melasma lesions was very heterogeneous. RCM also showed a significant increase in solar elastosis and blood vessels in the dermis. RCM is a non-invasive technique that detects pigmentary changes in melasma at a cellular level resolution. Therefore, RCM provides an innovative way to classify melasma by pigment changes.