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1.
Roland Hellinger Jeannie Horak Wolfgang Lindner 《Analytical and bioanalytical chemistry》2013,405(25):8105-8120
The fluorescent tag 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC; AccQ Fluor reagent kit from Waters) is a commercial N-terminal label for proteinogenic amino acids (AAs), designed for reversed-phase separation and quantification of the AA racemates. The applicability of AQC-tagged AAs and AA-type zwitterionic compounds was tested for enantiomer separation on the tert-butyl carbamate modified quinine and quinidine based chiral stationary phases, QN-AX and QD-AX employing polar-organic elution conditions. The investigated test analytes included the enantiomers of the positional isomers of isoleucine (Ile), threonine, homoserine, and 4-hydroxyproline. Furthermore, β-AAs, cyclic, and heterocyclic AAs including trans-2-amino-cyclohexane carboxylic acid and trans-2-aminocyclohexyl sulfonic acid, phenylalanine derivatives substituted with halides with increasing electronegativity and 3,4-dihydroxyphenylalanine, cysteine-related derivatives including homocysteic acid, methionine sulfone, cysteine-S-acetic acid, and cysteine-S-acetamide as well as a small range of aminophosphonic acids were enantioseparated. A mechanistic interaction study of AQC-AAs in comparison with fluoresceine isothiocyanate-labeled AAs was performed. The chiral and chemoselective recognition processes involved in enantiomer separation and retention was systematically discussed. Special emphasis was set on the influential factors exhibited by the chemistry, branching position, and spatial properties of the investigated zwitterionic analytes. The general interest to separate and distinguish between different types of branched-chained AAs and metabolic side products thereof lies in the toxicity of some of these compounds, which makes for instance allo–Ile an attractive candidate in disease-related biomarker research. Figure
Separation of the four AQC-tagged isomers of 4-hydroxyproline (trans-D, cis-D, trans-L and cis-L) on the chiral stationary phase QD-AX 相似文献
2.
Dayong Lee Ryan Vandrey Garry Milman Mateus Bergamaschi Damodara R. Mendu Jeannie A. Murray Allan J. Barnes Marilyn A. Huestis 《Analytical and bioanalytical chemistry》2013,405(23):7269-7279
Oral fluid (OF) is a valuable biological alternative for clinical and forensic drug testing. Evaluating OF to plasma (OF/P) cannabinoid ratios provides important pharmacokinetic data on the disposition of drug and factors influencing partition between matrices. Eleven chronic cannabis smokers resided on a closed research unit for 51 days. There were four 5-day sessions of 0, 30, 60, and 120 mg oral ?9-tetrahydrocannabinol (THC)/day followed by a five-puff smoked cannabis challenge on Day 5. Each session was separated by 9 days ad libitum cannabis smoking. OF and plasma specimens were analyzed for THC and metabolites. During ad libitum smoking, OF/P THC ratios were high (median, 6.1; range, 0.2–348.5) within 1 h after last smoking, decreasing to 0.1–20.7 (median, 2.1) by 13.0–17.1 h. OF/P THC ratios also decreased during 5-days oral THC dosing, and after the smoked cannabis challenge, median OF/P THC ratios decreased from 1.4 to 5.5 (0.04–245.6) at 0.25 h to 0.12 to 0.17 (0.04–5.1) at 10.5 h post-smoking. In other studies, longer exposure to more potent cannabis smoke and oromucosal cannabis spray was associated with increased OF/P THC peak ratios. Median OF/P 11-nor-9-carboxy-THC (THCCOOH) ratios were 0.3–2.5 (range, 0.1–14.7) ng/μg, much more consistent in various dosing conditions over time. OF/P THC, but not THCCOOH, ratios were significantly influenced by oral cavity contamination after smoking or oromucosal spray of cannabinoid products, followed by time-dependent decreases. Establishing relationships between OF and plasma cannabinoid concentrations is essential for making inferences of impairment or other clinical outcomes from OF concentrations. 相似文献
3.
Mark B. Hazuka Jeannie J. Kinzie Kathleen A. Davis David A. DeBoise 《Magnetic resonance imaging》1989,7(6):669-676
Thirteen patients with abnormal brain MR scans attributable to treatment-induced injury were retrospectively reviewed. All patients were treated with radiation therapy and 62% received chemotherapy. Five patients were graded as having severe white matter (WM) changes, four had moderate WM changes, and four had mild WM changes. CT was generally equivalent to MR in evaluation of severe and moderate WM abnormalities, whereas MR was superior to CT in detection of mild WM abnormalities. In general, the severity of changes depicted by MR/CT correlated with the extent of neurologic dysfunction. The most severe changes were seen in those patients treated with combination irradiation and chemotherapy. 相似文献
4.
A series of Zn(II)-Schiff bases I, II and III complexes were synthesized by reaction of o-phenylenediamine with 3-methylsalicylaldehyde, 4-methylsalicylaldehyde and 5-methylsalicylaldehyde. These complexes were characterized using FT-IR, UV-Vis, Diffuse reflectance UV-Vis, elemental analysis and conductivity. Complex III was characterized by XRD single crystal, which crystallizes in the triclinic system, space group P-1, with lattice parameters a?=?9.5444(2) Å, b?=?11.9407(2) Å, c?=?21.1732(3) Å, V?=?2390.24(7) Å3, D c ?=?1.408 Mg m?3, Z?=?4, F(000)?=?1050, GOF?=?0.981, R1?=?0.0502, wR2?=?0.1205. Luminescence property of these complexes was investigated in DMF solution and in the solid state. Computational study of the electronic properties of complex III showed good agreement with the experimental data. 相似文献
5.
Hofer S Ronacher A Horak J Graalfs H Lindner W 《Journal of chromatography. A》2011,1218(49):8925-8936
The aim of this study was to investigate functional increments of ion exchange type ligands, which may improve the performance of mixed-modal ligands for antibody capture out of feed solutions with pH above 6.0 and containing sodium chloride concentrations of 150 mM and higher. For this purpose several functional groups such as sulfonyl, sulfanyl, amide, methoxy, short alkyl and aromatic moieties were tested in combination with a strong sulfonic acid and/or a weak carboxylic acid group. Therefore a series of ligands were synthesized and subsequently coupled onto epoxide activated Fractogel® EMD. In the first instance, all materials were tested by static binding capacity measurements (SBC) under test conditions, comprising a wide variety of different sodium chloride concentrations and differing pH values ranging from 4.5 to 7.5. From these preliminary experiment it was found that especially the aromatic groups improved the binding of human immunoglobulin G (h-IgG) under isotonic conditions, while other increments, e.g. thiophilic or amide groups, were not able to increase the capacity significantly. Taking the SBC results into account, the most promising materials were investigated under dynamic binding conditions (DBC) with a reduced selection of test conditions (pH 5.5, 6.5 and 7.4 at 75 and 150 mM NaCl). N-benzoyl-homocysteine (material J) and 3,5-dimethoxybenzoyl-homocysteine (material K) showed 100% DBCs of 37 mg/mL and 32 mg/mL in the presence of 75 mM NaCl and pH 6.5. Material L carrying mercaptobenzoic acid as a ligand and tested with the same solution provided a 100% DBC of 68 mg/mL. The influence of Pluronic F68 in a mock feed solution as well as in cell culture supernatant was investigated with the best performing bio-affinity type adsorbent, material L. For the real sample feed subsequent SDS-PAGE was conducted for the collected fractions. 相似文献
6.
Soo PL Sidorov SN Mui J Bronstein LM Vali H Eisenberg A Maysinger D 《Langmuir : the ACS journal of surfaces and colloids》2007,23(9):4830-4836
There is increasing interest in the usefulness of block copolymer micelles as drug delivery vehicles. However, their subcellular distribution has not been explored extensively, mostly because of the lack of adequately labeled block copolymers. In a previous study, we showed that fluorescently labeled block copolymer micelles entered living cells and co-localized with cytoplasmic organelles selectively labeled with fluorescent dyes. The details of the observed co-localizations were, however, limited by the resolution of the fluorescence approach, which is ca. 500 nm. Using transmission electron microscopy (TEM), we established time- and concentration-dependent subcellular distributions of gold-labeled micelles within human embryonic kidney (HEK 293) cells and human lung carcinoma (A549) cells. Gold particles were incorporated into poly(4-vinylpyridine)-block-poly(ethylene oxide) (P4VP21-b-PEO45) micelles. Data from dynamic light scattering (DLS) and TEM analyses revealed that the sizes of the gold particles ranged from 4 to 8 nm. The cells survived up to 24 h in the presence of low gold-labeled micelle concentrations (0.73 microg/mL), but cell death occurred at higher concentrations (i.e., kidney cells are more susceptible than lung cells). Over 24 h periods of equivalent exposure, lung cells internalized significantly more gold-incorporated micelles than kidney cells. Although micelles were added to the cell culture media as dispersed colloidal particles, the presence of serum in these media caused aggregation. These aggregates occurred mainly close to the cell plasma membrane at early times (5-10 min); however, at later times (24 h) aggregated particles were seen inside endosomes and lysozomes. Thus, gold-incorporated (labeled) micelles can serve as a valuable extension of the fluorescence approach to visualizing the localization of micelles in subcellular compartments, improving the resolution by at least 20-fold. 相似文献
7.
Jose-Luis Sagripanti Avram Levy Jeannie Robertson Adam Merritt Timothy J. J. Inglis 《Photochemistry and photobiology》2009,85(4):978-986
The goal of this study was to determine the sensitivity of virulent Burkholderia pseudomallei to natural sunlight. We describe solar dosimetry calibrated to integrate radiation between 295 and 305 nm and an exposure system that minimizes thermal effects on bacterial cells. Burkholderia pseudomallei cells were either exposed to sunlight in UV transparent dishes or maintained in the dark covered by opaque foil. The cells maintained in the dark remained at constant levels for the duration of all experiments. The exposed cells nearby were killed with a kinetic studied through 5 Log10 inactivation. We found that cells in stationary phase of growth were nearly two-fold more resistant to sunlight than cells in lag or exponential growth. A virulent strain of B. pseudomallei that produced mucoid colonies showed sensitivity to sunlight similar to both a virulent strain that produced nonmucoid colonies and a strain of B. thailandensis . The inactivation of B. pseudomallei by sunlight in different types of water of environmental relevance or inside amoebae was investigated. The sensitivity of virulent B. pseudomallei was calculated and its comparison with previous studies employing monochromatic germicidal light (254 nm) is discussed . This may be the first report in the open literature of the inactivation of a virulent biological threat agent by natural sunlight. These data should assist in estimating the risk for contracting melioidosis and in predicting the time period during which B. pseudomallei remains infectious after an accidental or intentional release in the environment. 相似文献
8.
9.
K.M. AHMIDAJ.R.F. ARRUDA 《Journal of sound and vibration》2002,255(4):663-684
This paper discusses the well-known, but often misunderstood, concept of complex modes of dynamic structures. It shows how complex modes can be interpreted in terms of wave propagation phenomena caused by either localized damping or propagation to the surrounding media. Numerical simulation results are presented for different kinds of structures exhibiting modal and wave propagation characteristics: straight beams, an L-shaped beam, and a three-dimensional frame structure. The input/output transfer relations of these structures are obtained using a spectral formulation known as the spectral element method (SEM). With this method, it is straightforward to use infinite elements, usually known as throw-off elements, to represent the propagation to infinity, which is a possible cause of modal complexity. With the SEM model, the exact dynamic behavior of structures can be investigated. The mode complexity of these structures is investigated. It is shown that mode complexity characterizes a behavior that is half-way between purely modal and purely propagative. A coefficient for quantifying mode complexity is introduced. The mode complexity coefficient consists of the correlation coefficient between the real and imaginary parts of the eigenvector, or of the operational deflection shape (ODS). It is shown that, far from discontinuities, this coefficient is zero in the case of pure wave propagation in which case the plot of the ODS in the complex plane is a perfect circle. In the other extreme situation, a finite structure without damping (or with proportional damping), where the mode shape (or the ODS) is a straight line on the complex plane, has a unitary complexity coefficient. For simple beam structures, it is shown that the mode complexity factor can also be calculated by curve-fitting the mode to an ellipse and computing the ratio of its radii. 相似文献
10.
Jeannie Tsimis Kibitel Vivian Yee Daniel B. Yarosh 《Photochemistry and photobiology》1991,54(5):753-760
The phage T4 denV gene, coding for the pyrimidine-dimer specific T4 endonuclease V, was transfected into human repair-proficient fibroblasts, repair-deficient xeroderma pigmentosum fibroblasts, and into wild type CHO hamster cells. Transfectants maintained denV DNA and expressed denV mRNA. Purified T4 endonuclease V encapsulated in liposomes was also used to treat repair-proficient and -deficient human cells. The denV transfected clones and liposome-treated cells showed increased unscheduled DNA synthesis and enhanced removal of pyrimidine dimers compared to controls. Both denV gene transfection and endonuclease V liposome treatment enhanced post-UV survival in xeroderma pigmentosum cells but had no effect on survival in repair-proficient human or hamster cells. The results demonstrate that an exogenous DNA repair enzyme can correct the DNA repair defect in xeroderma pigmentosum cells and enhance DNA repair in normal cells. 相似文献