Optical excitation and detection of neuronal activity

Optogenetics has emerged as an exciting tool for manipulating neural activity, which in turn, can modulate behavior in live organisms. However, detecting the response to the optical stimulation requires electrophysiology with physical contact or fluorescent imaging at target locations, which is often limited by photobleaching and phototoxicity. In this paper, we show that phase imaging can report the intracellular transport induced by optogenetic stimulation. We developed a multimodal instrument that can both stimulate cells with high spatial resolution and detect optical pathlength changes with nanometer scale sensitivity. We found that optical pathlength fluctuations following stimulation are consistent with active organelle transport. Furthermore, the results indicate a broadening in the transport velocity distribution, which is significantly higher in stimulated cells compared to optogenetically inactive cells. It is likely that this label-free, contactless measurement of optogenetic response will provide an enabling approach to neuroscience.Comment: 20 pages, 5 figure

Anti-staphylococcal activity and mode of action of thioridazine photoproducts

Antibiotic resistance became an increasing risk for population health threatening our ability to fight infectious diseases. The objective of this study was to evaluate the activity of laser irradiated thioridazine (TZ) against clinically-relevant bacteria in view to fight antibiotic resistance. TZ in ultrapure water solutions was irradiated (1–240 min) with 266 nm pulsed laser radiation. Irradiated solutions were characterized by UV–Vis and FTIR absorption spectroscopy, thin layer chromatography, laser-induced fluorescence, and dynamic surface tension measurements. Molecular docking studies were made to evaluate the molecular mechanisms of photoproducts action against Staphylococcus aureus and MRSA. More general, solutions were evaluated for their antimicrobial and efflux inhibitory activity against a panel of bacteria of clinical relevance. We observed an enhanced antimicrobial activity of TZ photoproducts against Gram-positive bacteria. This was higher than ciprofloxacin effects for methicillin- and ciprofloxacin-resistant Staphylococcus aureus. Molecular docking showed the Penicillin-binding proteins PBP3 and PBP2a inhibition by sulforidazine as a possible mechanism of action against Staphylococcus aureus and MRSA strains, respectively. Irradiated TZ reveals possible advantages in the treatment of infectious diseases produced by antibiotic-resistant Gram-positive bacteria. TZ repurposing and its photoproducts, obtained by laser irradiation, show accelerated and low-costs of development if compared to chemical synthesis.publishersversionpublishe

TiO2 nanoparticles influence on rhodamine 6G droplet emission

This work aims to investigate the effect of TiO 2 nanoparticles addition on the fluorescence emission of solutions of Rhodamine 6G excited in micro-volumetric droplets. In this paper are presented the similarities and the differences of the emission spectra by modifying parameters such as TiO 2 concentration, solutions pH and laser fluence. The pumping laser source used was the second harmonic beam emitted by a pulsed ns Nd:YAG laser at 532 nm. Lasing emission is observed and it is favorised by the solution acidity and laser beam intensity. © 2018, Editura Academiei Romane. All rights reserved

TiO2 nanoparticles influence on rhodamine 6G droplet emission

This work aims to investigate the effect of TiO 2 nanoparticles addition on the fluorescence emission of solutions of Rhodamine 6G excited in micro-volumetric droplets. In this paper are presented the similarities and the differences of the emission spectra by modifying parameters such as TiO 2 concentration, solutions pH and laser fluence. The pumping laser source used was the second harmonic beam emitted by a pulsed ns Nd:YAG laser at 532 nm. Lasing emission is observed and it is favorised by the solution acidity and laser beam intensity. © 2018, Editura Academiei Romane. All rights reserved

Biological Evaluation of Products Formed from the Irradiation of Chlorpromazine with a 266 nm Laser Beam

Models that can predict consumer choices are essential technical support fordecision makers in many contexts. The focus of this thesis is to address predictionproblems in discrete choice models and to develop methods to increase the predictivepower of these models with application to car type choice. In this thesis we challengethe common practice of prediction that is using statistical inference to estimateand select the ‘best’ model and project the results to a future situation. We showthat while the inference approaches are powerful explanatory tools in validating theexisting theories, their restrictive theory-driven assumptions make them not tailormadefor predictions. We further explore how modeling considerations for inferenceand prediction are different.Different papers of this thesis present various aspects of the prediction problemand suggest approaches and solutions to each of them.In paper 1, the problem of aggregation over alternatives, and its effects on bothestimation and prediction, is discussed. The focus of paper 2 is the model selectionfor the purpose of improving the predictive power of discrete choice models. Inpaper 3, the problem of consistency when using disaggregate logit models for anaggregate prediction question is discussed, and a model combination is proposedas tool. In paper 4, an updated version of the Swedish car fleet model is appliedto assess a Bonus-Malus policy package. Finally, in the last paper, we present thereal world applications of the Swedish car fleet model where the sensitivity of logitmodels to the specification of choice set affects prediction accuracy.QC 20160115</p

Exposure of Chlorpromazine to 266 nm Laser Beam Generates New Species with Antibacterial Properties: Contributions to Development of a New Process for Drug Discovery

INTRODUCTION: Phenothiazines when exposed to white light or to UV radiation undergo a variety of reactions that result in degradation of parental compound and formation of new species. This process is slow and may be sped up with exposure to high energy light such as that produced by a laser. METHODS: Varying concentrations of Chlorpromazine Hydrochloride (CPZ) (2-20 mg/mL in distilled water) were exposed to 266 nm laser beam (time intervals: 1-24 hrs). At distinct intervals the irradiation products were evaluated by spectrophotometry between 200-1500 nm, Thin Layer Chromatography, High Pressure Liquid Chromatography (HPLC)-Diode Array Detection, HPLC tandem mass spectrometry, and for activity against the CPZ sensitive test organism Staphylococcus aureus ATCC 25923. RESULTS: CPZ exposure to 266 nm laser beam of given energy levels yielded species, whose number increased with duration of exposure. Although the major species produced were Promazine (PZ), hydroxypromazine or PZ sulfoxide, and CPZ sulfoxide, over 200 compounds were generated with exposure of 20 mg/mL of CPZ for 24 hrs. Evaluation of the irradiation products indicated that the bioactivity against the test organism increased despite the total disappearance of CPZ, that is due, most probably, to one or more new species that remain yet unidentified. CONCLUSIONS: Exposure of CPZ to a high energy (6.5 mJ) 266 nm laser beam yields rapidly a large number of new and stable species. For biological grade phenothiazines (in other words knowing the impurities in the samples: solvent and solute) this process may be reproducible because one can control within reasonably low experimental errors: the concentration of the parent compound, the laser beam wavelength and average energy, as well as the duration of the exposure time. Because the process is "clean" and rapid, it may offer advantages over the pyrogenically based methods for the production of derivatives

Studies on laser induced emission of microdroplets containing Rhodamine 6G solutions in water doped with TiO2 nanoparticles

Studies on the emission spectra of microdroplets containing Rh6G solutions in water doped with TiO2 nanoparticles are reported. The excitation is made by the second harmonic of a pulsed Nd:YAG laser at 532 nm, pulse duration at half maximum 6 ns and energy varied between 6 and 10 mJ. The laser induced emission spectra are analyzed function of TiO2 concentration and pumping laser energy. Comparison between fluorescence dispersed spectra emitted by pendant droplets containing TiO2 nanoparticles with respect to Rh6G water solutions droplets pumped in the same conditions is made. The surface tension measurements of the samples show that with variation of dye and nanoparticles concentrations, surface phenomena take place and influence the behavior of the droplet fluorescence. (C) 2016 Elsevier B.V. All rights reserved

Photosensitized cleavage of some olefins as potential linkers to be used in drug delivery

International audienc

Novel Mg-0.5Ca-xMn Biodegradable Alloys Intended for Orthopedic Application: An In Vitro and In Vivo Study

Mg-based biodegradable materials, used for medical applications, have been extensively studied in the past decades. The in vitro cytocompatibility study showed that the proliferation and viability (as assessed by quantitative MTT-assay&mdash;3-(4,5-dimethyltiazol-2-yl)-2,5-diphenyl tetrazolium bromide) were not negatively affected with time by the addition of Mn as an alloying element. In this sense, it should be put forward that the studied alloys don&rsquo;t have a cytotoxic effect according to the standard ISO 10993-5, i.e., the level of the cells&rsquo; viability (cultured with the studied experimental alloys) attained both after 1 day and 5 days was over 82% (i.e., 82, 43&ndash;89, 65%). Furthermore, the fibroblastic cells showed variable morphology (evidenced by fluorescence microscopy) related to the alloy sample&rsquo;s proximity (i.e., related to the variation on the Ca, Mg, and Mn ionic concentration as a result of alloy degradation). It should be mentioned that the cells presented a polygonal morphology with large cytoplasmic processes in the vicinity of the alloy&rsquo;s samples, and a bipolar morphology in the remote region of the wells. Moreover, the in vitro results seem to indicate that only 0.5% Mn is sufficient to improve the chemical stability, and thus the cytocompatibility; from this point of view, it could provide some flexibility in choosing the right alloy for a specific medical application, depending on the specific parameters of each alloy, such as its mechanical properties and corrosion resistance. In order to assess the in vivo compatibility of each concentration of alloy, the pieces were implanted in four rats, in two distinct body regions, i.e., the lumbar and thigh. The body&rsquo;s reaction was followed over time, 60 days, both by general clinical examinations considering macroscopic changes, and by laboratory examinations, which revealed macroscopic and microscopic changes using X-rays, CT(Computed Tomography), histology exams and SEM (Scanning Electron Microscopy). In both anatomical regions, for each of the tested alloys, deformations were observed, i.e., a local reaction of different intensities, starting the day after surgery. The release of hydrogen gas that forms during Mg alloy degradation occurred immediately after implantation in all five of the groups examined, which did not affect the normal functionality of the tissues surrounding the implants. Imaging examinations (radiological and CT) revealed the presence of the alloy and the volume of hydrogen gas in the lumbar and femoral region in varying amounts. The biodegradable alloys in the Mg-Ca-Mn system have great potential to be used in orthopedic applications