Mechanisms of action of vitamin B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) in pain: a narrative review.

Pain is a complex sensory and emotional experience with nociceptive, nociplastic, and neuropathic components. An involvement of neurotropic B vitamins (B1 - thiamine, B6 - pyridoxine, and B12 - cyanocobalamin) as modulators of inflammation and pain has been long discussed. New evidence suggests their therapeutic potential in different pain conditions. In this review, we discuss the main role of neurotropic B vitamins on different nociceptive pathways in the nervous system and to describe their analgesic action mechanisms. The performed literature review showed that, through different mechanisms, these vitamins regulate several inflammatory and neural mediators in nociceptive and neuropathic pain. Some of these processes include aiming the activation of the descending pain modulatory system and in specific intracellular pathways, anti-inflammatory, antioxidative and nerve regenerative effects. Moreover, recent data shows the antinociceptive, antiallodynic, and anti-hyperalgesic effects of the combination of these vitamins, as well as their synergistic effects with known analgesics. Understanding how vitamins B1, B6, and B12 affect several nociceptive mechanisms can therefore be of significance in the treatment of various pain conditions.

Different growth regimes in InP nanowire growth mediated by Ag nanoparticles.

We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.

Characterization of electroforming-free titanium dioxide memristors.

Metal-insulator-metal (MIM) structures based on titanium dioxide have demonstrated reversible and non-volatile resistance-switching behavior and have been identified with the concept of the memristor. Microphysical studies suggest that the development of sub-oxide phases in the material drives the resistance changes. The creation of these phases, however, has a number of negative effects such as requiring an elevated voltage, increasing the device-to-device variability, damaging the electrodes due to oxygen evolution, and ultimately limiting the device lifetime. In this work we show that the deliberate inclusion of a sub-oxide layer in the MIM structure maintains the favorable switching properties of the device, while eliminating many of the negative effects. Electrical and microphysical characterization of the resulting structures was performed, utilizing X-ray and electron spectroscopy and microscopy. In contrast to structures which are not engineered with a sub-oxide layer, we observed dramatically reduced microphysical changes after electrical operation.

The impact of the RGD peptide on osteoblast adhesion and spreading on zinc-substituted hydroxyapatite surface.

The incorporation of zinc into the hydroxyapatite structure (ZnHA) has been proposed to stimulate osteoblast proliferation and differentiation. Another approach to improve cell adhesion and hydroxyapatite (HA) performance is coating HA with adhesive proteins or peptides such as RGD (arginine-glycine-aspartic acid). The present study investigated the adhesion of murine osteoblastic cells to non-sintered zinc-substituted HA disks before and after the adsorption of RGD. The incorporation of zinc into the HA structure simultaneously changed the topography of disk's surface on the nanoscale and the disk's surface chemistry. Fluorescence microscopy analyses using RGD conjugated to a fluorescein derivative demonstrated that ZnHA adsorbed higher amounts of RGD than non-substituted HA. Zinc incorporation into HA promoted cell adhesion and spreading, but no differences in the cell density, adhesion and spreading were detected when RGD was adsorbed onto ZnHA. The pre-treatment of disks with fetal bovine serum (FBS) greatly increased the cell density and cell surface area for all RGD-free groups, overcoming the positive contribution of zinc to cell adhesion. The presence of RGD on the ZnHA surface impaired the effects of FBS pre-treatment possibly due to competition between FBS proteins and RGD for surface binding sites.

Effects of periodontal non-surgical therapy plus azithromycin on glycemic control in patients with diabetes: a randomized clinical trial.

BACKGROUND AND OBJECTIVE: Periodontitis may alter the systemic condition in patients with diabetes and hence interfere with glycemic control. The objective of this study was to determine the quantifiable changes in glycated hemoglobin (HbA1C) after periodontal non-surgical therapy plus azithromycin in a mixed population of patients with poorly controlled diabetes. MATERIALS AND METHODS: One hundred and five patients were randomized to receive non-surgical therapy plus azythromycin (AZ-Sca =33), non-surgical therapy plus placebo (PB-Sca = 37) and supragingival prophylaxis plus azithromycin (AZ-Pro = 35). Glycated hemoglobin, glycemia and periodontal parameters were measured at baseline, 3, 6 and 9 mo after treatment. RESULTS: Periodontal parameters were improved in the AZ-Sca and PB-Sca groups as compared to the AZ-Pro group. A greater reduction in probing depth was observed in the AZ-Sca as compared to the PB-Sca group. Improvement in clinical attachment level was similar between AZ-Sca and PB-Sca groups. A reduction from 8.0% to 7.2% (∆0.8%; p < 0.05) in HbA1C was observed in the AZ-Sca at 9 mo as compared to the PB-Sca group in which the reduction was from 7.9% to 7.6% (∆0.3%). There was no decrease in HbA1C in the AZ-Pro group over time. Mean glycemia values decreased from 195 mg/dL to 159.2 mg/dL (∆35.8 mg/dL; p < 0.05) in the AZ-Sca group whereas a decrease from 194 mg/dL to 174.8 mg/dL (∆19.2 mg/dL) in the PB-Sca group at 9 mo was observed. There were no differences between the AZ-Sca and PB-Sca groups for glycemic parameters. No improvement in glycemic values in the AZ-Pro group was observed. CONCLUSIONS: A modest improvement in glycemic control was detected with a trend towards the use of non-surgical therapy plus AZ as compared to the placebo.

Experimental evidence and structural modeling of nonstoichiometric (010) surfaces coexisting in hydroxyapatite nano-crystals.

High-resolution transmission electron microscopy (HRTEM) and ab initio quantum-mechanical calculations of electronic structure were combined to investigate the structure of the hydroxyapatite (HA) (010) surface, which plays an important role in HA interactions with biological media. HA was synthesized by in vitro precipitation at 37°C. HRTEM images revealed thin elongated rod nanoparticles with preferential growth along the [001] direction and terminations parallel to the (010) plane. The focal series reconstruction (FSR) technique was applied to develop an atomic-scale structural model of the high-resolution images. The HRTEM simulations identified the coexistence of two structurally distinct terminations for (010) surfaces: a rather flat Ca(II)-terminated surface and a zig-zag structure with open OH channels. Density functional theory (DFT) was applied in a periodic slab plane-wave pseudopotential approach to refine details of atomic coordination and bond lengths of Ca(I) and Ca(II) sites in hydrated HA (010) surfaces, starting from the HRTEM model.