The effect of different workplace nanoparticles on the immune systems of employees

Currently, nanoparticles are widely present in the environment and are being used in various industrial technologies. Nanoparticles affect immune functions, causing different immune responses. The aim of the current study was to evaluate several cytokines, interleukin (IL)-1b, IL-6, IL-8, tumour necrosis factor-a (TNF-α), interferon-γ, adhesive molecule sICAM-1, macrophage inhibitory protein 1a (MIP1a) and secretory immunoglobulin A, in nasal lavage fluid and in the peripheral blood of healthy subjects exposed to workplace nanoparticles. Thirty-six employees from three different environments were examined: 12 from a metalworking company, 12 from a woodworking company and 12 office workers. The nanoparticles in the different workplaces were detected in the air in the immediate vicinity of the employees. The particle number concentration and surface area values were significantly higher in the workplaces of the metal- and woodworking industries, but concentrations of mass were lower (the measurements were performed by an electrical low-pressure impactor ELPI+). Energy dispersive X-ray spectroscopy (EDS, an attachment to a high-resolution SEM) was used to provide elemental analysis or chemical characterization of the dust particles in a low-vacuum field-free mode operating at a potential of 15 kV spot 3.0. The technique used provided quantitative and spatial analyses of the distribution of elements through mapping (two to three parallel measurements) and point analysis (four to five parallel measurements). Samples from the metal industry contained more ultramicroscopic and nanometric particles, e.g. toxic metals such as Zn, Mn and Cr, and fewer microscopic dust particles. The nasal lavage and peripheral blood were taken at the beginning and the end of the working week, when immune indices were measured. Our data showed a statistically significant increased level of the pro-inflammatory cytokine TNF-α in serum in both exposed groups compared with office workers as well as a higher level of TNF-α in workers from the woodworking company compared with the metalworking employees. We found an elevated level of IL-6 in the exposed groups as well as an elevated level of IL-8 in the nasal lavage in woodworking employees after work.     

The crystal and molecular structure of sodium 4‐(2,4,6‐triisopropylbenzoyl)benzoate in terms of the photochemical behaviour of the anion

Contrary to the known 4‐(2,4,6‐triisopropylbenzoyl)benzoate salts, di‐μ‐aqua‐bis[tetraaquasodium(I)] bis[4‐(2,4,6‐triisopropylbenzoyl)benzoate] dihydrate, [Na₂(H₂O)₁₀](C₂₃H₂₇O₃)₂·2H₂O, (1), does not undergo a photochemical Norrish–Yang reaction in the crystalline state. In order to explain this photochemical inactivity, the intermolecular interactions were analyzed by means of the Hirshfeld surface and intramolecular geometrical parameters describing the possibility of a Norrish–Yang reaction were calculated. The reasons for the behaviour of the title salt are similar crystalline environments for both the o‐isopropyl groups in the anion, resulting in similar geometrical parameters and orientations, and that these interaction distances differ significantly from those found in salts where the photochemical reaction occurs.     

Crystal Structures of N-(4-butyryl-3-hydroxyphenyl)acetamide Monohydrate and 4-(4-Chlorophenyl)-2-methyl-4-oxobutanoic Acid: Possibilities of Yang Photocyclization

Abstract  

N-(4-butyryl-3-hydroxyphenyl)acetamide monohydrate, (I), and 4-(4-chlorophenyl)-2-methyl-4-oxobutanoic acid, (II), are photochemically inert, which is a result of their conformation. The geometrical parameters describing the molecular conformation and possibilities of the Yang photocyclization in crystals have been calculated and discussed. Compound (I) forms double ribbons along the a axis, stabilized by hydrogen bonds and π⋯π interactions. Compound (II) forms dimers. (I): triclinic, space group \textP[`1] {\text{P}}\bar{1} , a = 6.9291(12) ?, b = 7.5736(16) ?, c = 13.0528(18) ?, α = 79.643(17)°, β = 85.818(15)°, γ = 63.97(2)°, Z = 2. (II): monoclinic, space group P2₁/c, a = 11.904(2) ?, b = 9.6508(12) ?, c = 10.666(2) ?, β = 110.64(2)°, Z = 4.     

Rapid RP-LC Method with Fluorescence Detection for Analysis of Fexofenadine in Human Plasma

A rapid and sensitive reversed-phase high-performance liquid chromatographic method for analysis of fexofenadine in human plasma has been developed and optimized. The analytes were extracted from biological samples by solid-phase extraction on hydrophilic–lipophilic balance cartridges. LC separation was performed on a C₁₈ analytical column (125 mm × 4 mm i.d., 5-μm particles) with 42:58 (v/v) acetonitrile–water adjusted to pH 2.7 with 85% orthophosphoric acid as mobile phase. Fluorescence detection was performed with excitation at 230 nm and emission at 290 nm. The total time for chromatographic separation was 7 min. The method was validated in accordance with EU guidelines by analysis of plasma samples fortified with fexofenadine at concentrations between 0.05 and 800 ng mL^?1. Calibration plots were linear in this range. Mean recovery was typically 94.03% and the detection limit was 0.05 ng mL^?1. The time required for quantitative analysis is shorter than that required by other methods.     

Determination of butoxyacetic acid (biomarker of ethylene glycol monobutyl ether exposure) in human urine candidate reference material

Ethylene glycol monobutyl ether (EGBE), an industrial solvent, is absorbed by the body not only by inhalation but also by dermal absorption (liquid or vapour). EGBE is metabolized to butoxyacetic acid (BAA). Pooled freeze-dried urine candidate reference material (RM) was prepared from urine obtained from persons occupationally exposed to EGBE. This material has the advantage of containing butoxyacetic acid in both the free and conjugated (glutamine and glycine) forms, as found in native urine. In all GC method modifications used, acid hydrolysis was used to release BAA from its conjugated form. The amount of butoxyacetic acid in homogeneity and stability testing was measured by GC after derivatisation with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide. Detection was by MS in EI mode, in the authors’ laboratory. For interlaboratory comparison of the reference material GC methods with MS, FID, and ECD were used. Different extraction solvents (dichloromethane–isopropanol 2:1, ethyl acetate, or dichloromethane) and derivatisation reagents (trimethylsilyldiazomethane, N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide) were used. Using ANOVA (at the statistical level α = 0.05) no changes were found in the concentration of butoxyacetic acid during fifteen month isochronous stability testing, or in homogeneity testing. The uncertainty contributions were u _h = 8.8 mg L⁻¹ and u _s = 6.5 mg L⁻¹. The concentration of butoxyacetic acid in freeze-dried urine RM was evaluated from the results of eight laboratory data sets within an interlaboratory comparison by use of the interactive statistical software IPECA. The contribution to total uncertainty derived from interlaboratory comparison was u _i = 12.7 mg L⁻¹. The reference value (c = 273 ± 33 mg L⁻¹) is an unweighted arithmetic average of accepted results. The value is traceable to the pure butoxyacetic acid (98% w/w; Acros Organic #257760010) used as calibrant. The uncertainty given is combined expanded uncertainty derived from the results from interlaboratory comparison, and from homogeneity and stability tests (k = 2). The reference material will be used to verify method performance in the biological monitoring of occupational exposure to EGBE.     

2‐Oxo‐2‐phenyl‐N‐[(R)‐1‐phenylethyl]acetamide and N,N‐dimethyl‐2‐(1‐naphthyl)‐2‐oxoacetamide: possibility of Yang photocyclization in a crystal

The crystal structures of 2‐oxo‐2‐phenyl‐N‐[(R)‐1‐phenylethyl]acetamide, C₁₆H₁₅NO₂, (I), and N,N‐dimethyl‐2‐(1‐naphthyl)‐2‐oxoacetamide, C₁₄H₁₃NO₂, (II), were determined in an attempt to understand the reason for the lack of Yang photocyclization in their respective crystals. In the case of (I), the long distance between the O atom of the carbonyl group and the γ‐H atom, and between the C atom of the carbonyl group and the γ‐C atom, preclude Yang photocyclization. For (II), the deviation of the γ‐H atom from the plane of the carbonyl group and interactions between the naphthalene rings are regarded as possible reasons for the chemical inertia. The two independent molecules of (I) differ in their conformation. N—H...O hydrogen bonds link molecules of (I) into chains extended along the b axis.     

Bestimmung aliphatischer und aromatischer S?urechloride

Zusammenfassung Eine Methode zur Bestimmung aliphatischer und aromatischer Säurechloride wird beschrieben. Hierbei werden die Säurechloride mit acetonhaltiger Natriumjodidlösung quantitativ zu Natriumchlorid und Säurejodid umgesetzt. Das in Aceton unlösliche Natriumchlorid wird abfiltriert, in Wasser gelöst und nach Volhard bestimmt. Die üblichen Zersetzungsprodukte stören die Bestimmung nicht. Die Fehler liegen meist unter 1%.

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Summary A method is recommended for the determination of aliphatic and aromatic acid chlorides. It consists in converting the acid chlorides to the iodides by sodium iodide in acetonic solution, filtering off the sodium chloride formed quantitatively by this reaction and insoluble in acetone, dissolving it in water and titrating by Volhard's method. The determination is not influenced by the usual decomposition products of acid chlorides. Errors are mostly smaller than 1%.

     

Reactions of 9-substituted guanines with bromomalondialdehyde in aqueous solution predominantly yield glyoxal-derived adducts

Reactions of 9-ethylguanine, 2'-deoxyguanosine and guanosine with bromomalondialdehyde in aqueous buffers over a wide pH-range were studied. The main products were isolated and characterized by (1)H and (13)C NMR and mass spectroscopy. The final products formed under acidic and basic conditions were different, but they shared the common feature of being derived from glyoxal. Among the 1 : 1 adducts, 1,N(2)-(trans-1,2-dihydroxyethano)guanine adduct (6) predominated at pH < 6 and N(2)-carboxymethylguanine adduct (10a,b) at pH > 7. In addition to these, an N(2)-(4,5-dihydroxy-1,3-dioxolan-2-yl)methylene adduct (11a,b) and an N(2)-carboxymethyl-1,N(2)-(trans-1,2-dihydroxyethano)guanine adduct (12) were obtained at pH 10. The results of kinetic experiments suggest that bromomalondialdehyde is significantly decomposed to formic acid and glycolaldehyde under the conditions required to obtain guanine adducts. Glycolaldehyde is oxidized to glyoxal, which then modifies the guanine base more readily than bromomalondialdehyde. Besides the glyoxal-derived adducts, 1,N(2)-ethenoguanine (5a-c) and N(2),3-ethenoguanine adducts (4a-c) were formed as minor products, and a transient accumulation of two unstable intermediates, tentatively identified as 1,N(2)-(1,2,2,3-tetrahydroxypropano)(8) and 1,N(2)-(2-formyl-1,2,3-trihydroxypropano)(9) adducts, was observed.     

Muon spin rotation in superconductors

By means of the muon spin rotation technique (⁺SR), the temperature dependence of the magnetic field inside the normal-conducting domains of high-purity tantalum crystals in the intermediate state has been measured in the temperature range 2.36K+SR. Possible applications of these findings to the study of long-range diffusion of positive muons at low temperatures are indicated.