Comparison of two methods for noninvasive determination of carotenoids in human and animal skin: Raman spectroscopy versus reflection spectroscopy

Based on compelling in vivo and in vitro studies on human skin, carotenoids are thought to be of great interest as powerful antioxidants acting to prevent free‐radical‐induced damages, including premature skin ageing and the development of skin diseases such as cancer. Among the available techniques that are suitable for noninvasive determination of carotenoids in human skin, are resonance Raman spectroscopy (RRS) and reflection spectroscopy (RS). For RS, a LED‐based miniaturized spectroscopic system (MSS) was developed for noninvasive measurement of carotenoids in human skin. The optimization and subsequent calibration of the MSS was performed with the use of RRS. A strong correlation between the carotenoid concentration determined by the RS and for the RRS system was achieved for human skin in vivo (R = 0.88) and for bovine udder skin in vitro (R = 0.81). (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Complex action of tyramine,tryptamine and histamine on native and recombinant ASICs

Proton-gated channels of the ASIC family are widely distributed in the mammalian brain, and, according to the recent data, participate in synaptic transmission. However, ASIC-mediated currents are small, and special efforts are required to detect them. This prompts the search for endogenous ASIC ligands, which can activate or potentiate these channels. A recent finding of the potentiating action of histamine on recombinant homomeric ASIC1a has directed attention to amine-containing compounds. In the present study, we have analyzed the action of histamine, tyramine, and tryptamine on native and recombinant ASICs. None of the compounds caused potentiation of native ASICs in hippocampal interneurons. Furthermore, when applied simultaneously with channel activation, they produced voltage-dependent inhibition. Experiments on recombinant ASIC1a and ASIC2a allowed for an interpretation of these findings. Histamine and tyramine were found to be inactive on the ASIC2a, while tryptamine demonstrated weak inhibition. However, they induce both voltage-dependent inhibition of open channels and voltage-independent potentiation of closed/desensitized channels on the ASIC1a. We suggest that the presence of an ASIC2a subunit in heteromeric native ASICs prevents potentiation but not inhibition. As a result, the inhibitory action of histamine, which is masked by a strong potentiating effect on the ASIC1a homomers, becomes pronounced in experiments with native ASICs.     

On the reliability of quantitation of biological effect in drug–interceptor–DNA systems

Relative insensitivity of theoretical estimation of biological effect in drug–interceptor–DNA systems is found with respect to variation of parameters of quasiphysiological conditions. The “inertness” of the biological response, in part, justifies the use of parameters of intermolecular interaction, derived from independent physicochemical experiments, in estimation of relative biological effect in the theory of interceptor/protector action.