Non-viral delivery and optimized optogenetic stimulation of retinal ganglion cells led to behavioral restoration of vision

Stimulation of retinal neurons using optogenetics via use of chanelrhodopsin-2 (ChR2) has opened up a new direction for restoration of vision for treatment of retinitis pigmentosa (RP). Here, we report non-viral in-vivo electroporation of degenerated retina of adult RP-mice with ChR2-plasmids and subsequent in-vivo imaging of retina to confirm expression. Further, we demonstrate that in addition to efficient non-viral delivery of ChR2 to a specific retinal layer, threshold level of stimulation light needs to be delivered onto the retina for achieving successful behavioral outcome. Measurement of intensity of light reaching the retina of RP-mouse models along with geometrical optics simulation of light propagation in the eye is reported in order to determine the stimulating source position for optimal light delivery to the retina. The light-guided navigation of mice with ChR2 expressing retinal ganglion cells was found to be significantly improved over a long distance in correlation with stimulation intensity

Optically-driven red blood cell rotor in linearly polarized laser tweezers

We have constructed a dual trap optical tweezers set-up around an inverted microscope where both the traps can be independently controlled and manipulated in all the three dimensions. Here we report our observations on rotation of red blood cells (RBCs) in a linearly polarized optical trap. Red blood cells deform and become twisted in hypertonic phosphate buffer saline and when trapped, experience an unbalanced radiation pressure force. The torque generated from the unbalanced force causes the trapped RBC to rotate. Addition of Ca++ ions in the solution, keeping the osmolarity same, makes the cell membranes stiffer and the cells deform less. Thus the speed of rotation of the red blood cells can be controlled, as less deformation and in turn less asymmetry in shape produces less torque under the radiation pressure resulting in slower rotation at the same laser power

Evaluation of stress based on multiple distinct modalities using machine learning techniques

Nowadays, one of the most time-consuming and complex study subjects is predicting working professionals' stress levels. It is thus crucial to estimate active professionals' stress levels to aid their professional development. Several machine learning (ML) and deep learning (DL) methods have been created in earlier articles for this goal. But they also have drawbacks, such as increased design complexity, a high rate of misclassification, a high incidence of mistakes, and reduced efficiency. Considering these issues, the objective of this study is to make a prognosis about the stress levels experienced by working professionals by using a cutting-edge deep learning model known as the convolutional neural networks (CNN). In this paper, we offer a model that combines CNN-based classification with dataset preprocessing, feature extraction, and optimum feature selection using principal component analysis (PCA). When the raw data is preprocessed, duplicate characteristics are eliminated, and missing values are filled

Comparative analysis of deep learning models for various nonalcoholic fatty liver disease datasets

Fatty liver disease is caused by increased liver buildup or weight above 5-10%. This disorder is widespread in people with diabetes, overweight persons, and metabolic syndrome patients. Clinical decision support systems can improve liver failure diagnosis and prediction to reduce this situation. Many liver failure models have drawbacks, and liver failure prediction is still a problem. This work uses four large open-access critical care patient datasets to create and verify liver failure risk prediction models. This study aims to construct a clinically applicable diagnostic and predictive model that evaluates the probability or risk of liver failure in intensive care unit (ICU) patients using extreme gradient boosting (XGBoost), artificial neural networks (ANN), multi-layer perceptron (MLP), Modular Neural Network (MNN), and generalized feed forward (GFF). We evaluated performance metrics using these models: accuracy, sensitivity, specificity, and predictive accuracy

Directing growth cones of optic axons growing with laser scissors and laser tweezers

We have combined a laser scissors and a laser tweezers to study, (1) the response of nerve fiber growth cones to laserinduced damage on single axons, and (2) localized microfluidic flow generated by laser-driven spinning birefringent particles. In the laser scissors study, sub-axotomy damage elicits a growth cone response whether damage is on the same or an adjacent axon. In laser tweezers study, the axon growth cones turn in response to the optically driven microfluidic flow. In summary, both the laser scissors and the laser tweezers studies elicit growth cone turning responses

Comparative analysis of different laser systems to study cellular responses to DNA damage in mammalian cells

Proper recognition and repair of DNA damage is critical for the cell to protect its genomic integrity. Laser microirradiation ranging in wavelength from ultraviolet A (UVA) to near-infrared (NIR) can be used to induce damage in a defined region in the cell nucleus, representing an innovative technology to effectively analyze the in vivo DNA double-strand break (DSB) damage recognition process in mammalian cells. However, the damage-inducing characteristics of the different laser systems have not been fully investigated. Here we compare the nanosecond nitrogen 337 nm UVA laser with and without bromodeoxyuridine (BrdU), the nanosecond and picosecond 532 nm green second-harmonic Nd:YAG, and the femtosecond NIR 800 nm Ti:sapphire laser with regard to the type(s) of damage and corresponding cellular responses. Crosslinking damage (without significant nucleotide excision repair factor recruitment) and single-strand breaks (with corresponding repair factor recruitment) were common among all three wavelengths. Interestingly, UVA without BrdU uniquely produced base damage and aberrant DSB responses. Furthermore, the total energy required for the threshold H2AX phosphorylation induction was found to vary between the individual laser systems. The results indicate the involvement of different damage mechanisms dictated by wavelength and pulse duration. The advantages and disadvantages of each system are discussed

Broad-Band Activatable White-Opsin

The authors would like to thank C. Cote and K. Dhakal (UTA) for help during initiation of the project. SM would like to thank K. Deisseroth (Stanford University) for ChR2 and C1V1 plasmids, and J. Lin (UCSD) for the ReaChR construct.Currently, the use of optogenetic sensitization of retinal cells combined with activation/inhibition has the potential to be an alternative to retinal implants that would require electrodes inside every single neuron for high visual resolution. However, clinical translation of optogenetic activation for restoration of vision suffers from the drawback that the narrow spectral sensitivity of an opsin requires active stimulation by a blue laser or a light emitting diode with much higher intensities than ambient light. In order to allow an ambient light-based stimulation paradigm, we report the development of a ‘white-opsin’ that has broad spectral excitability in the visible spectrum. The cells sensitized with white-opsin showed excitability at an order of magnitude higher with white light compared to using only narrow-band light components. Further, cells sensitized with white-opsin produced a photocurrent that was five times higher than Channelrhodopsin-2 under similar photo-excitation conditions. The use of fast white-opsin may allow opsin-sensitized neurons in a degenerated retina to exhibit a higher sensitivity to ambient white light. This property, therefore, significantly lowers the activation threshold in contrast to conventional approaches that use intense narrow-band opsins and light to activate cellular stimulation.Yeshttp://www.plosone.org/static/editorial#pee