UV-mediated DNA strand breaks in corneal epithelial cells assessed using the comet assay procedure

Ultraviolet (UV)-mediated DNA damage in various tissues has been well documented. However, research on the damaging effect of UV irradiation on the DNA of corneal epithelium is scarce, even though this is of interest because the cornea is directly exposed to damaging solar (UV) radiation. In this study, we developed a corneal epithelium Comet assay model to assess the background DNA damage (as strand breaks) in cells retrieved from different layers of the porcine corneal epithelium, and to investigate the effect of UV irradiation on DNA damage in corneal epithelial cells. Results show that the background DNA strand breaks decreased significantly (P < 0.001) toward deeper layers of the epithelium. Exposure to the same intensity (0.216 J/cm2) of UVA, UVB and UVC caused a significant (P < 0.001) increase in DNA strand breaks of deeper-layer cells: mean +/- SD %DNA scores (10 gels per treatment, with 100 irradiated cells scored per gel) were 10.2% +/- 1.4% for UVA, 27.4% +/- 4.6% for UVB, and 14.7% +/- 1.8% for UVC compared with 4.2% +/- 0.5% for controls (ambient room light). This study has shown for the first time that the Comet assay for DNA strand breaks can be used successfully with corneal epithelial cells. This report will support future studies investigating environmental influences on corneal health and the assessment of possible protective strategies, and in applying DNA lesion-specific versions of the Comet assay in this corneal epithelial cell model.     

Preparation and conformation of dioxocalix[4]arene derivatives

CrO(3) oxidation experiments conducted on atropisomeric forms of 2 (2(paco), 2(1,3)(-)(alt), and 2(1,2)(-)(alt)) indicate that under the reaction conditions only methylene groups located between pairs of geminal rings oriented in an anti disposition are oxidized to carbonyls. NMR data suggest that the tetrahydroxydioxocalix[4]arenes 7 and 9 adopt the partial cone and 1,2-alternate conformations, respectively. In the crystal structure of 7.2EtOAc the dioxocalixarene adopts a partial cone conformation, whereas 9 adopts in the crystal a 1,2-alternate conformation. In both conformations, pairs of geminal rings connected to a carbonyl are oriented in an anti fashion. The relative stability of the partial cone and 1,2-alternate conformations of 7 and 9 is underestimated by MM3 calculations. The topomerization barriers of 7 and 9 are 12.8 and 13.6 kcal mol(-)(1), respectively.     

Synthesis and structure of novel heterocyclic aminotelluranes

A series of novel 6-alkoxy-12H, 14H-[1,2,3]benzoxatellurazino[2,3-b]-[1,2,3]benzoxatellurazines 3 was synthesized from tetraalkoxytelluranes and bis(2-hydroxybenzyl)amines. ¹H, ¹³C and ¹²⁵Te NMR studies suggest that these aminotelluranes, unlike their orthoamidoester analogs, have a rigid trans-fused conformation. A preferential trans-fused conformation was also deduced from ab initio MO calculations of a model oxatellurazinooxatellurazine 7, using the STO-3G and SBK basis sets, and the Gaussian-92 program, which imply that the trans-fused aminotellurane is more stable than the corresponding cis isomer by 10.3 kcal/mol.     

Efficient Synthesis of (−)‐(R)‐Muscone by Enantioselective Protonation

A new synthesis of (?)‐(R)‐muscone ((R)‐ 1 ) by means of enantioselective protonation of a bicyclic ketone enolate as the key step (see 6 →(S)‐ 4 in Scheme 2) is presented. The C₁₅ macrocyclic system is obtained by ozonolysis (Scheme 7).     

Hauptregelflächen einer Verallgemeinerten Regelfläche mit Zentralregelfläche

We consider generalized ruled surfaces in euclidean n-space ⁿ with k-dimensional generators and central ruled surface of dimension k–m+1 (O < m < k). Every orthogonal trajectoryy of the generators of defines a principal ruled surface _y with generators totally orthogonal to the generators of . In each generator of _y there exists an ellipsoid — called the indicatrix of the distribution parameters — which is defined by the distribution parameters of the tangent spaces to or _y. Formulars will be given for the distribution parameters of and _y .

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Herrn Prof. Dr. H.R. Müller zum 70. Geburtstag     

Effect of dental finishing instruments on the surface roughness of composite resins as elucidated by atomic force microscopy

Roughness increases significantly after finishing procedures. The aim of this study was to assess by the atomic force microscope (AFM) the effect of finishing instruments on the surface roughness of composite resins. A nanofiller composite resin (Filtek Supreme, 3MP) were selected. The finishing procedures were done with a 30-blade carbide bur (C) and a 30-M), and (3) finishing instrument (FM, PM, FC, FD, PC, PD). The mean surface roughness was evaluated by AFM in the contact mode. FM and PM groups were assessed statistically by the Student's T test, and FC, FD, PC, PD groups were submitted to variance analysis (ANOVA), both at 5% significance. The mean surface roughness values, in nanometers, were FM, 23.63 (b); FC, 283.88 (c); FD, 510.55 (d); PM, 12.52 (a); PC, 343.98 (c); PD, 531.64 (d). Microhybrid composite displayed less roughness than nanofiller composite in the absence of finishing procedures. The 30-blade carbide bur produced less roughness compared to the extra fine diamond bur.     

Development and validation of a sensitive assay for the quantification of imatinib using LC/LC‐MS/MS in human whole blood and cell culture

We developed and validated a semi‐automated LC/LC‐MS/MS assay for the quantification of imatinib in human whole blood and leukemia cells. After protein precipitation, samples were injected into the HPLC system and trapped onto the enrichment column (flow 5 mL/min); extracts were back‐flushed onto the analytical column. Ion transitions [M + H]⁺ of imatinib (m/z = 494.3 → 394.3) and its internal standard trazodone (372.5 → 176.3) were monitored. The range of reliable response was 0.03–75 ng/mL. The inter‐day precisions were: 8.4% (0.03 ng/mL), 7.2% (0.1 ng/mL), 6.5% (1 ng/mL), 8.2% (10 ng/mL) and 4.3% (75 ng/mL) with no interference from ion suppression. Autosampler stability was 24 hs and samples were stable over three freeze–thaw cycles. This semi‐automated method is simple with only one manual step, uses a commercially available internal standard, and has proven to be robust in larger studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Assembly of a fluorescent cyclodextrin polyrotaxane and its detection by fluorescence microscopy

A straightforward method for the assembly of fluorescent polyrotaxanes is described here. The consecutive threading of N‐(6^I‐desoxy‐β‐cyclodextrin‐6^I‐yl)‐N′‐(5‐fluoresceinyl)‐thiourea, β‐CD‐F , and α‐CD onto poly(N,N‐dimethyliminium‐hexamethylen‐N′,N′‐dimethyliminium‐decamethylene chloride), I‐6,10 , leads to a fluorescent polyrotaxane. Free β‐CD‐F could be distinguished from threaded β ‐ CD‐F by gel electrophoresis. Since the dissociation of threaded α‐CD rings is sterically hindered, the obtained polyrotaxanes are kinetically stable at 25 °C, and they did not require further stabilization by the attachment of stopper groups at the chain ends. Single polyrotaxane entities could be visualized with both fluorescence microscopy and atomic force microscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6223–6230, 2009     

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