Benzylidene acetals of 1,2- and 1,3-glycols are easily cleft by diisobutylaluminum hydride in a toluene solution at 0 °C–room temperature to give the corresponding monobenzyl ethers of the glycols. In general the reaction proceeds excellently in regioselective manner depending on the stereochemical environment.

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Background Two types of atopic dermatitis (AD) have been proposed, with different pathophysiological mechanisms underlying this seemingly heterogeneous disorder. The extrinsic type shows high IgE levels presumably as a consequence of skin barrier damage and feasible allergen permeation, whereas the intrinsic type exhibits normal IgE levels and is not mediated by allergen-specific IgE. Objectives To investigate the relationship between pruritus perception threshold and skin barrier function of patients with AD in a comparison between the extrinsic and intrinsic types. Methods Enrolled in this study were 32 patients with extrinsic AD, 17 with intrinsic AD and 24 healthy individuals. The barrier function of the stratum corneum was assessed by skin surface hydration and transepidermal water loss (TEWL), and pruritus perception was evaluated by the electric current perception threshold (CPT) of sensory nerves upon neuroselective transcutaneous electric stimulation. Results Skin surface hydration was significantly lower and TEWL was significantly higher in extrinsic AD than intrinsic AD or normal controls. Although there was no statistically significant difference in CPT among extrinsic AD, intrinsic AD and normal controls, CPT was significantly correlated with skin surface hydration and inversely with TEWL in intrinsic AD and normal controls, but not extrinsic AD. Finally, CPT was correlated with the visual analogue scale of itch in the nonlesional skin of patients with extrinsic but not intrinsic AD. Conclusions Patients with extrinsic AD have an impaired barrier, which increases the pre-existing pruritus but rather decreases sensitivity to external stimuli. In contrast, patients with intrinsic AD retain a normal barrier function and sensory reactivity to external pruritic stimuli.

Chromatographic and spectrometric discrimination of fentanyl and its 24 analogues are discussed. Twenty-three of 25 samples were discriminated from each other by gas chromatography (GC), and the combination of GC and mass spectrometry enabled discrimination of all 25 samples. Condensed-phase infrared spectrometry was also useful for the differentiation of structurally similar compounds, but vapor-phase infrared spectra were not useful for discrimination of fentanyls.

Samarium(III)-(R)- or (S)-propylenediaminetetraacetate complex resolved the enantiomer signals of alpha-amino acids on high-field (1)H and (13)C NMR with remarkably less line broadening than was previously reported for the Eu(III) complex of the same ligand. A widely observed regularity between the absolute configuration of enantiomers and the relative shift of their NMR signals is useful for the assignment of absolute configuration.

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