The aim of this study is to investigate the structural organization and oligomerization properties of the sensory kinase protein DevS using low-angle light scattering (LALS) and gel filtration chromatography (HPLC). In addition, the structural characteristics of FixL and BSA were investigated and compared with DevS to better elucidate LALS technique. DevS is a direct and specific O2 sensing protein in Mycobacterium tuberculosis and acts as an activator of the transcription factor protein DevR. This latter triggers the latency state of tuberculosis under hypoxic conditions. DevS has been briefly evaluated under different conditions of concentration, ionic strength and temperature. LALS and gel filtration (HPLC) analysis were performed right after DevS purification process. The results of LALS for BSA proved to be highly reliable with a Rh value of c.a. 3.7 nm. Considering BSA a globular protein, the molecular weight estimative, using LALS was near 67 KDa, which is reasonably within the value reported in the literature. Preliminary LALS results showed a hydrodynamic radius (Rh) varying from 4.2-15.0 nm for DevS protein, and an average of 6.7 nm. These data supported, along with gel filtration, a dimer (~130 KDa) and tetramer (255 KDa) as the main DevS species. Additionally, it was found higher oligomeric species by gel filtration suggesting either an equilibrium of oligomers or an aggregation process that deserves further studies.
An optical system that conjugates the patient’s pupil to the plane of a Hartmann-Shack (HS) wavefront sensor has been
simulated using optical design software. And an optical bench prototype is mounted using mechanical eye device, beam
splitter, illumination system, lenses, mirrors, mirrored prism, movable mirror, wavefront sensor and camera CCD. The
mechanical eye device is used to simulate aberrations of the eye. From this device the rays are emitted and travelled by
the beam splitter to the optical system. Some rays fall on the camera CCD and others pass in the optical system and
finally reach the sensor. The eye models based on typical in vivo eye aberrations is constructed using the optical design
software Zemax. The computer-aided outcomes of each HS images for each case are acquired, and these images are
processed using customized techniques. The simulated and real images for low order aberrations are compared using
centroid coordinates to assure that the optical system is constructed precisely in order to match the simulated system.
Afterwards a simulated version of retinal images is constructed to show how these typical eyes would perceive an
optotype positioned 20 ft away. Certain personalized corrections are allowed by eye doctors based on different Zernike
polynomial values and the optical images are rendered to the new parameters. Optical images of how that eye would see
with or without corrections of certain aberrations are generated in order to allow which aberrations can be corrected and
in which degree. The patient can then “personalize” the correction to their own satisfaction. This new approach to
wavefront sensing is a promising change in paradigm towards the betterment of the patient-physician relationship.
We used three dimensional cell cultures (3D) based on the magnetic levitation method (MLM) to evaluate cytotoxicity of
photodynamic therapy (PDT). First, we decorated Hep G2 and MDA-MB-321 cells with NanoShuttle by introducing it in
the media and incubated overnight. Next day, we transferred the cells to a 6-well plate and placed a magnetic driver on
the top of the plate to start levitation. We monitored the formation of the 3D cell culture by optical microscopy and after
four days, we added the photosensitizer Photogem (PG) in the culture media in concentrations of 50, 25, 12.5,
6.25μg/ml. We incubated them for 24 hours, after that we washed the cultures with PBS and added fresh media. Samples
were then illuminated for 600s using a 630nm LED-based device, generating light intensities of 30 mW/cm2 in a total light fluence of 18 J/cm2. Following the illumination, we added fresh media, and 30 hours later, the 3D structures were broken using a pipettor and the cells seeded in 96 well plates, 105 cells per well, with a magnetic drive placed on the bottom of the plate to create cell culture dots. After 24 hours, we used a MTT assay to evaluate PDT cytotoxicity. The PDT effect, evaluated by the half maximal effective concentration (EC50), in MDA-MB-231 cells (EC50 =3.14 μg/ml) is more aggressive compared to the effect of PDT in Hep G2 cells (EC50 = 7.48 μg/ml). It suggests that the cell culture structure and its interaction facilitated the PG uptake and consequently elevated the Photodynamic effect for MDA-MB-231.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.