d(CGGTGGT) forms an octameric parallel G-quadruplex via stacking of unusual G(:C):G(:C):G(:C):G(:C) octads

Among non-canonical DNA secondary structures, G-quadruplexes are currently widely studied because of their probable involvement in many pivotal biological roles, and for their potential use in nanotechnology. The overall quadruplex scaffold can exhibit several morphologies through intramolecular or intermolecular organization of G-rich oligodeoxyribonucleic acid strands. In particular, several G-rich strands can form higher order assemblies by multimerization between several G-quadruplex units. Here, we report on the identification of a novel dimerization pathway. Our Nuclear magnetic resonance, circular dichroism, UV, gel electrophoresis and mass spectrometry studies on the DNA sequence dCGGTGGT demonstrate that this sequence forms an octamer when annealed in presence of K(+) or NH(4)(+) ions, through the 5'-5' stacking of two tetramolecular G-quadruplex subunits via unusual G(:C):G(:C):G(:C):G(:C) octads.     

Oxygen free radical scavenger properties of dehydroepiandrosterone

The microsomes from dehydroepiandrosterone (DHEA)-supplemented animals are good hydroxyl radical scavengers, as demonstrated through electron spin resonance and deoxyribose degradation. The ability of DHEA-supplemented microsomes to react with superoxide radical was also demonstrated through the inhibition of nitro-blue tetrazolium reduction determined by superoxide radicals produced in a hypoxanthine–xanthine oxidase system. DHEA-enriched microsomes, obtained from acutely DHEA-treated rats, become resistant to iron-dependent lipid peroxidation triggered by H₂O₂/FeSO₄ and ascorbate/FeSO₄. The direct addition of DHEA to microsomes from untreated rats failed to prevent iron-dependent lipid peroxidation, even if the microsomes were preincubated with DHEA for up to 15 min, indicating that in vivo transformation is required before antioxidant action can be exerted. © 1998 John Wiley & Sons, Ltd.     

Skin microbiota of first cousins affected by psoriasis and atopic dermatitis

Background

Psoriasis and atopic dermatitis (AD) are chronic inflammatory skin diseases, which negatively influence the quality of life. In the last years, several evidences highlighted the pivotal role of skin bacteria in worsening the symptomatology of AD and psoriasis. In the present study we evaluated the skin microbiota composition in accurately selected subjects affected by (AD) and psoriasis.

Methods

Three first cousins were chosen for the study according to strict selection of criteria. One subject was affected by moderate AD, one had psoriasis and the last one was included as healthy control. Two lesional skin samples and two non-lesional skin samples (for AD and psoriatic subjects) from an area of 2 cm² behind the left ear were withdrawn by mean of a curette. For the healthy control, two skin samples from an area of 2 cm² behind the left ear were withdrawn by mean of a curette. DNA was extracted and sequencing was completed on the Ion Torrent PGM platform. Culturing of Staphylococcus aureus from skin samples was also performed.

Results

The psoriatic subject showed a decrease in Firmicutes abundance and an increase in Proteobacteria abundance. Moreover, an increase in Streptococcaceae, Rhodobacteraceae, Campylobacteraceae and Moraxellaceae has been observed in psoriatic subject, if compared with AD individual and control. Finally, AD individual showed a larger abundance of S. aureus than psoriatic and healthy subjects. Moreover, the microbiota composition of non-lesional skin samples belonging to AD and psoriatic individuals was very similar to the bacterial composition of skin sample belonging to the healthy control.

Conclusion

Significant differences between the skin microbiota of psoriatic individual and healthy and AD subjects were observed.

     

Bilateral tDCS on Primary Motor Cortex: Effects on Fast Arm Reaching Tasks

BackgroundThe effects produced by transcranial direct current stimulation (tDCS) applied to the motor system have been widely studied in the past, chiefly focused on primary motor cortex (M1) excitability. However, the effects on functional tasks are less well documented.ObjectiveThis study aims to evaluate the effect of tDCS-M1 on goal-oriented actions (i.e., arm-reaching movements; ARM), in a reaction-time protocol.Methods13 healthy subjects executed dominant ARM as fast as possible to one of two targets in front of them while surface EMG was recorded. Participants performed three different sessions. In each session they first executed ARM (Pre), then received tDCS, and finally executed Post, similar to Pre. Subjects received three different types of tDCS, one per session: In one session the anode was on right-M1 (AR), and the cathode on the left-M1 (CL), thus termed AR-CL; AL-CR reversed the montage; and Sham session was applied likewise. Real stimulation was 1mA-10min while subjects at rest. Three different variables and their coefficients of variation (CV) were analyzed: Premotor times (PMT), reaction-times (RT) and movement-times (MT).Resultstriceps-PMT were significantly increased at Post-Sham, suggesting fatigue. Results obtained with real tDCS were not different depending on the montage used, in both cases PMT were significantly reduced in all recorded muscles. RT and MT did not change for real or sham stimulation. RT-CV and PMT-CV were reduced after all stimulation protocols.ConclusiontDCS reduces premotor time and fatigability during the execution of fast motor tasks. Possible underlying mechanisms are discussed.     

Transferrin receptor 2 is emerging as a major player in the control of iron metabolism

Our knowledge of mammalian iron metabolism has advanced dramatically over recent years. Iron is an essential element for virtually all living organisms. Its intestinal absorption and accurate cellular regulation is strictly required to ensure the coordinated synthesis of the numerous iron-containing proteins involved in key metabolic processes, while avoiding the uptake of excess iron that can lead to organ damage. A range of different proteins exist to ensure this fine control within the various tissues of the body. Among these proteins, transferrin receptor (TFR2) seems to play a key role in the regulation of iron homeostasis. Disabling mutations in TFR2 are responsible for type 3 hereditary hemochromatosis (Type 3 HH). This review describes the biological properties of this membrane receptor, with a particular emphasis paid to the structure, function and cellular localization. Although much information has been garnered on TFR2, further efforts are needed to elucidate its function in the context of the iron regulatory network.     

Synthesis and characterization of tetra-end linked oligonucleotides capable of forming monomolecular G-quadruplexes

The chemical synthesis of two new G-rich Tetra-End-Linked-oligodeoxyribonucleotides (TEL-ODNs) as well as (1)H-NMR and CD spectra of the corresponding monomolecular quadruplexes (IVa and IVb) has been reported. The new TEL-ODNs, characterized by the presence of short branches in the linker moiety, could be very useful for the achievement of monomolecular quadruplexes with predetermined strand orientation.     

Optical tweezers as a probe for oligodeoxyribonucleotide structuration

The aim of this work is to investigate if the optical tweezers (OT) are suitable as a diagnostic tool for monitoring the oligodeoxyribonucleotide (ODN) structural behavior in solution. Preliminary experiments, performed on the quadruplex formed by the ODN sequence TGGGGT, showed that the OT can be used as a probe for ODN structuration by monitoring the medium viscosity changes associated with ODN folding-unfolding processes.