A lipidomic platform establishment for structural identification of skin ceramides with non-hydroxyacyl chains

The stratum corneum (SC) is the outermost layer of skin that functions as a barrier and protects against environmental influences and transepidermal water loss. Its unique morphology consists of keratin-enriched corneocytes embedded in a distinctive mixture of lipids containing mainly ceramides, free fatty acids, and cholesterol. Ceramides are sphingolipids consisting of sphingoid bases, which are linked to fatty acids by an amide bond. Typical sphingoid bases in the skin are composed of dihydrosphingosine (dS), sphingosine (S), phytosphingosine (P), and 6-hydroxysphingosine (H), and the fatty acid acyl chains are composed of non-hydroxy fatty acid (N), α-hydroxy fatty acid (A), ω-hydroxy fatty acid (O), and esterified ω-hydroxy fatty acid (E). The 16 ceramide classes include several combinations of sphingoid bases and fatty acid acyl chains. Among them, N-type ceramides are the most abundant in the SC. Mass spectrometry (MS)/MS analysis of N-type ceramides using chip-based direct infusion nanoelectrospray-ion trap mass spectrometry generated the characteristic fragmentation pattern of both acyl and sphingoid units, which could be applied to structural identification of ceramides. Based on the MS/MS fragmentation patterns of N-type ceramides, comprehensive fragmentation schemes were proposed. In addition, mass fragmentation patterns, which are specific to the sphingoid backbone of N-type ceramides, were found in higher m/z regions of tandem mass spectra. These characteristic and general fragmentation patterns were used to identify N-type ceramides in human SC. Based on established MS/MS fragmentation patterns of N-type ceramides, 52 ceramides (including different classes of NS, NdS, NP, and NH) were identified in human SC. The MS/MS fragmentation patterns of N-type ceramides were characterized by interpreting their product ion scan mass spectra. This information may be used to identify N-type ceramides in the SC of human, rat, and mouse skin.     

Interactions between spiropyrans and room-temperature ionic liquids: photochromism and solvatochromism

A series of imidazolium-based room-temperature ionic liquids (RTILs) containing anions from organic carboxylic acids were prepared. A set of dye probes, including Reichardt's dye (30), 4-nitrioaniline, and N, N-diethyl-4-nitroaniline, were used to determine the ET(30) scales and the Kamlet-Taft parameters (pi*, alpha, and beta) of the RTILs. On the basis of the polarity properties, these RTILs were categorized into three groups: group A with beta >0.9, alpha <0.9; group B with beta <0.9, alpha <0.9; and group C with beta <0.9, alpha >0.9. Interactions of these RTILs with four photochromic spiropyran derivatives (SP-I, SP-II, SP-III, and SP-IV) were investigated. It was found that the spiropyrans could present photochromism (positive or negative) or not, depending mainly on the polarity properties of the RTILs and also on the structure itself. A new spectroscopic method based on the molecular transition energy of the spiropyran probes (ESP) was proposed to determine the polarity of those protic or fluorine-containing RTILs, which were failed with the Reichardt's dye (30) probe.     

Fluorescence energy transfer-labeled primers for high-performance forensic DNA profiling

A fluorescence energy transfer (ET) dye-labeled STR typing system (ET 16-plex) is developed for the markers used in the commercial STR typing kit PowerPlex 16, and its performance assessed using a 96-lane microfabricated capillary array electrophoresis (muCAE) system. The ET 16-plex amplicons displayed 1.6-9-fold higher fluorescence intensities compared to those produced using the single-dye (SD)-labeled multiplex kits. The ET multiplex delivered full STR profiles from 62.5 pg of DNA; half the input required for the SD kits while maintaining a similar heterozygote allele balance. This increased sensitivity should improve typing of poor-quality DNA samples by making minor or imbalanced alleles more readily detectable at the low copy number (LCN) threshold. The ET 16-plex also generated complete profiles with only 28 PCR cycles; this capability should improve LCN typing by reducing the amplification time and drop-in allele incidence. To confirm the practical advantages of ET-labeled primers, six previously problematic casework samples were tested and only the ET 16-plex kit was able to capture additional allele data. The successful development and demonstration of ET primers for higher sensitivity STR typing offers a simple solution to improving current commercial multiplex typing capability. The superior spectral properties and universal compatibility with any primer sequence provided by ET cassettes will make future multiplex construction more facile and straightforward. The pairing of ET cassette technology with the muCAE system illustrates not only an enhanced STR typing platform, but a significant step toward a higher-efficiency forensic laboratory enabled by better chemistry and microfluidics.     

A multi-residue method for the determination of 203 pesticides in rice paddies using gas chromatography/mass spectrometry

This work reports a rapid, specific and sensitive multi-residue method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM) using one quantification ion and two identification ions for the routine analysis of 203 pesticides in rice paddies. Analyses of fortified rice paddy samples were performed at different levels (0.05, 0.20 and 0.50 mg kg⁻¹). Mean recoveries from five replicates ranged from 75% to 115%, with coefficients of variation lower than 17%. The limit of quantification was in the range of 0.002-0.05 mg kg⁻¹ for the pesticides. 1040 rice paddy samples were analyzed for method application.     

The reactions of cyclotriphosphazene with 2-(2-hydroxyethylamino)ethanol. Spectroscopic studies of the derived products

Abstract

The reactions of cyclotriphosphazene (1) with 2-(2-hydroxyethylamino)-ethanol (2) were investigated. 2-(2-hydroxyethylamino)-ethanol (2) is a tri-functional reagent consisting of both aliphatic hydroxyl and the secondary amino groups and its nucleophilic substitution reactions with cylotriphosphazene can lead to different product types; open chain, spiro, ansa, bridged and their mixtures. The reactions with one, two and three equimolar ratios of 2-(2-hydroxyethylamino)-ethanol, in the presence of NaH at 0–10?°C and at room temperature gave the following cyclotriphosphazene derivatives: one mono-spiro, N₃P₃Cl₄[O–(CH₂)₂–NH–(CH₂)₂–O] (3, 1:1, r.t.); its isomer mono-ansa (5, 1:1, r.t.); one dispiro, N₃P₃Cl₂[O–(CH₂)₂–NH–(CH₂)₂–O]₂ (4, 1:1, r.t.); its isomer spiro-ansa (6, 1:2, r.t.); and one single-bridged compound with spiro substituted units, N₃P₃Cl₃[O–(CH₂)₂–NH–(CH₂)₂–O]₃N₃P₃Cl₃ (7, 1:3, at 0–10?°C); as well as single-, N₃P₃Cl₅[O–(CH₂)₂–NH–(CH₂)₂–O]N₃P₃Cl₅ (8, 1:2, r.t.), double-, N₃P₃Cl₄[O–(CH₂)₂–NH–(CH₂)₂–O]₂N₃P₃Cl₄ (9, 1:2, r.t.), and tri-bridged, N₃P₃Cl₃[O–(CH₂)₂–NH–(CH₂)₂–O]₃N₃P₃Cl₃ (10, 1:3, at 0–10?°C) derivatives. Triple-bridged derivative is the major product in this system. The structures of the novel-derived compounds were characterized by TLC-MS, FT-IR, elemental analysis, ¹H, and ³¹P NMR spectral.     

4-1BB (CD137) signals depend upon CD28 signals in alloimmune responses

Our previous study has demonstrated that there is a significant delay of Balb/c cardiac allograft rejection in the C57BL/6 4-1BB-deficient knockout recipient. In this study, we examined the effect of combined blockade of the 4-1BB and CD28 costimulatory pathways on cardiac allograft rejection in the C57BL/6-->Balb/c model. A long-term cardiac allograft survival was induced in CD28/4-1BB- deficient mice (>100 days survival in 3 of 4 mice), which was comparable with CD28-deficient mice (>100 days survival in 2 of 5 mice; P<0.2026). There was no long-term cardiac allograft survival in either wild-type (WT) or 4-1BB-deficient mice, even though 4-1BB-deficient recipients showed a significant delay of cardiac allograft rejection than WT mice. An in vitro mixed leukocyte reaction (MLR) assay showed that 4-1BB-deficient and WT mouse T cells had a similar responsiveness to allostimulation, whereas CD28- and CD28/4-1BB-deficient mouse T cells had a defective responsiveness to allostimulation. Furthermore, 4-1BB-deficient mice showed a similar CTL but an elevated Ab response against alloantigens as compared to WT mice, and the alloimmune responses of 4-1BB-deficient mice were abrogated in the CD28-deficient background. Overall, these results indicate that the CD28 costimulatory pathway plays a major role in the alloimmune response and that 4-1BB signals are dependent upon CD28 signals.     

An olefin disconnection strategy for the practical synthesis of (+)-brefeldin A: olefin cross metathesis and intramolecular Horner-Wadsworth-Emmons olefination

The practical and convergent total synthesis of (+)-brefeldin A has been achieved by an olefin disconnection strategy. Key features of the total synthesis include the efficient formation of C2 and C10 olefins, employing an olefin cross metathesis (CM) reaction and an intramolecular HWE olefination, respectively.     

Bio-functionalization of cotton,silk, and leather using different in-situ silver nanoparticle synthesis modules,and their antibacterial properties

Research on Chemical Intermediates - We present a novel and in-situ strategy to synthesize silver nanoparticles (AgNPs) onto cotton, leather, and silk fabrics by three different methods: a green...     

New building block for polyhydroxylated piperidine: total synthesis of 1,6-dideoxynojirimycin

(3R,4S)-3-Hydroxy-4-N-allyl-N-Boc-amino-1-pentene 10, an important precursor for the synthesis of polyhydroxylated piperidines, has been achieved as a single diastereomer without racemization via vinyl Grignard addition to N-Boc-N-allyl aminoaldehyde 9, which was derived from an enantiopure natural amino acid. Having forged a tetrahydropyridine ring scaffold 13 from 10 in 85% yield via RCM using Grubbs II catalyst, we were able to effect its stereodivergent dihydroxylation, via a common epoxide intermediate to yield a range of interesting hydroxylated piperidines, including ent-1,6-dideoxynojirimycin (ent-1,6-dDNJ) 1 (28% overall yield) and 5-amino-1,5,6-trideoxyaltrose 2 (29% over all yield) in excellent dr. To the best of our knowledge, our synthesis of ent-1,6-dDNJ 1 is the most expeditious to date.     

The stability of semi-interpenetrating polymer networks based on sulfonated polyimide and poly(ethylene glycol) diacrylate for fuel cell applications

A series of the semi-interpenetrating polymer network (semi-IPN) membranes based on sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and characterized comparing with pure sulfonated polyimide membrane and commercially available membrane, Nafion^® 117. The proton conductivity increased with the increase of poly(ethylene glycol) diacrylate contents in spite of the decrease in ion exchange capacity which is a key factor to improve the proton conductivity. The water stability of semi-IPN membranes containing poly(ethylene glycol) diacrylate is higher than the pure sulfonated polyimide membrane. Morphological structure showed that amorphous nature of the films also increased with the poly(ethylene glycol) diacrylate contents, which could make a crosslink, so that the crystallinity of polyimide could disappear. Semi-IPN membranes based on sulfonated polyimide and poly(ethylene glycol) diacrylate, which show good conductivity comparable to Nafion^® 117 in the range of 20-50% content of poly(ethylene glycol) diacrylate, could be promising proton conducting membranes in fuel cell application.