31 research outputs found
Electro-optically tunable microring resonators in lithium niobate
Optical microresonators have recently attracted a growing attention in the
photonics community. Their applications range from quantum electro-dynamics to
sensors and filtering devices for optical telecommunication systems, where they
are likely to become an essential building block. The integration of nonlinear
and electro-optical properties in the resonators represents a very stimulating
challenge, as it would incorporate new and more advanced functionality. Lithium
niobate is an excellent candidate material, being an established choice for
electro-optic and nonlinear optical applications. Here we report on the first
realization of optical microring resonators in submicrometric thin films of
lithium niobate. The high index contrast films are produced by an improved
crystal ion slicing and bonding technique using benzocyclobutene. The rings
have radius R=100 um and their transmission spectrum has been tuned using the
electro-optic effect. These results open new perspectives for the use of
lithium niobate in chip-scale integrated optical devices and nonlinear optical
microcavities.Comment: 15 pages, 8 figure
Massage-like stroking boosts the immune system in mice
Recent clinical evidence suggests that the therapeutic effect of massage involves the immune system and that this can be exploited as an adjunct therapy together with standard drug-based approaches. In this study, we investigated the mechanisms behind these effects exploring the immunomodulatory function of stroking as a surrogate of massage-like therapy in mice. C57/BL6 mice were stroked daily for 8 days either with a soft brush or directly with a gloved hand and then analysed for differences in their immune repertoire compared to control non-stroked mice. Our results show that hand-but not brush-stroked mice demonstrated a significant increase in thymic and splenic T cell number (p lt 0.05; p lt 0.01). These effects were not associated with significant changes in CD4/CD8 lineage commitment or activation profile. The boosting effects on T cell repertoire of massage-like therapy were associated with a decreased noradrenergic innervation of lymphoid organs and counteracted the immunosuppressive effect of hydrocortisone in vivo. Together our results in mice support the hypothesis that massage-like therapies might be of therapeutic value in the treatment of immunodeficiencies and related disorders and suggest a reduction of the inhibitory noradrenergic tone in lymphoid organs as one of the possible explanations for their immunomodulatory function
A new class of glycomimetic drugs to prevent free fatty acid-induced endothelial dysfunction
Background: Carbohydrates play a major role in cell signaling in many biological processes. We have developed a set of glycomimetic drugs that mimic the structure of carbohydrates and represent a novel source of therapeutics for endothelial dysfunction, a key initiating factor in cardiovascular complications. Purpose: Our objective was to determine the protective effects of small molecule glycomimetics against free fatty acidinduced endothelial dysfunction, focusing on nitric oxide (NO) and oxidative stress pathways. Methods: Four glycomimetics were synthesized by the stepwise transformation of 2,5dihydroxybenzoic acid to a range of 2,5substituted benzoic acid derivatives, incorporating the key sulfate groups to mimic the interactions of heparan sulfate. Endothelial function was assessed using acetylcholineinduced, endotheliumdependent relaxation in mouse thoracic aortic rings using wire myography. Human umbilical vein endothelial cell (HUVEC) behavior was evaluated in the presence or absence of the free fatty acid, palmitate, with or without glycomimetics (1µM). DAF2 and H2DCFDA assays were used to determine nitric oxide (NO) and reactive oxygen species (ROS) production, respectively. Lipid peroxidation colorimetric and antioxidant enzyme activity assays were also carried out. RTPCR and western blotting were utilized to measure Akt, eNOS, Nrf2, NQO1 and HO1 expression. Results: Ex vivo endotheliumdependent relaxation was significantly improved by the glycomimetics under palmitateinduced oxidative stress. In vitro studies showed that the glycomimetics protected HUVECs against the palmitateinduced oxidative stress and enhanced NO production. We demonstrate that the protective effects of preincubation with glycomimetics occurred via upregulation of Akt/eNOS signaling, activation of the Nrf2/ARE pathway, and suppression of ROSinduced lipid peroxidation. Conclusion: We have developed a novel set of small molecule glycomimetics that protect against free fatty acidinduced endothelial dysfunction and thus, represent a new category of therapeutic drugs to target endothelial damage, the first line of defense against cardiovascular disease