Human stromal stem cells isolated from limbal biopsies prevented corneal scarring in a murine model of corneal wounding. All Eyes on Limbal Stem Cells Our corneas—transparent, collagen-based structures that allow us to see—are easily damaged by trauma and infection, resulting in scarring and, in many cases, blindness. Although corneal transplant is the clinical norm, adverse immune responses and a shortage of cornea donors are serious limitations. Basu and colleagues devised a personalized cell-based, nonsurgical approach to prevent corneal scarring. They obtained mesenchymal stem cells from the human limbus (the region between the cornea and the sclera) and confirmed that they could be differentiated into keratocytes (corneal cells) in vitro. The human limbal biopsy–derived stromal cells, or LBSCs, were then placed in a fibrin gel and applied to the surface of debridement wounds in mice. The LBSCs were able to regenerate damaged stromal tissue in the animals, resembling native corneal tissue. Because these cells can be obtained directly from the patient and because fibrin-based products are already used in people, this approach could translate soon to treat stromal scarring, a major cause of corneal blindness. Conventional allograft therapy for corneal scarring is widespread and successful, but donor tissue is not universally available, and some grafts fail owing to rejection and complications such as endothelial failure. We investigated direct treatment of corneal scarring using autologous stem cells, a therapy that, if successful, could reduce the need for corneal grafts. Mesenchymal cells were expanded from small superficial, clinically replicable limbal biopsies of human cadaveric corneo-scleral rims. Limbal biopsy–derived stromal cells (LBSCs) expanded rapidly in media containing human serum, were highly clonogenic, and could generate spheres expressing stem cell genes (ABCG2, Nestin, NGFR, Oct4, PAX6, and Sox2). Human LBSCs differentiated into keratocytes expressing characteristic marker genes (ALDH3A1, AQP1, KERA, and PTGDS) and organized a thick lamellar stroma-like tissue containing aligned collagen and keratan sulfate proteoglycans when cultured on aligned nanofiber substrata. When engrafted into mouse corneal wounds, LBSCs prevented formation of light-scattering scar tissue containing fibrotic matrix components. The presence of LBSCs induced regeneration of ablated stroma with tissue exhibiting lamellar structure and collagen organization indistinguishable from that of native tissue. Because the limbus can be easily biopsied from either eye of an affected individual and LBSCs capable of corneal stromal remodeling can be expanded under xeno-free autologous conditions, these cells present a potential for autologous stem cell–based treatment of corneal stromal blindness.

Limbal Biopsy Derived Stromal Stem Cells Prevent Corneal Scarring

A review of dose calculation approaches with cone beam CT in photon and proton therapy.

The detection of emotions is fundamental in many areas related to health and well-being. This paper presents the identification of the level of arousal in older people by monitoring their electrodermal activity (EDA) through a commercial device. The objective was to recognize arousal changes to create future therapies that help them to improve their mood, contributing to reduce possible situations of depression and anxiety. To this end, some elderly people in the region of Murcia were exposed to listening to various musical genres (flamenco, Spanish folklore, Cuban genre and rock/jazz) that they heard in their youth. Using methods based on the process of deconvolution of the EDA signal, two different studies were carried out. The first, of a purely statistical nature, was based on the search for statistically significant differences for a series of temporal, morphological, statistical and frequency features of the processed signals. It was found that Flamenco and Spanish Folklore presented the highest number of statistically significant parameters. In the second study, a wide range of classifiers was used to analyze the possible correlations between the detection of the EDA-based arousal level compared to the participants’ responses to the level of arousal subjectively felt. In this case, it was obtained that the best classifiers are support vector machines, with 87% accuracy for flamenco and 83.1% for Spanish Folklore, followed by K-nearest neighbors with 81.4% and 81.5% for Flamenco and Spanish Folklore again. These results reinforce the notion of familiarity with a musical genre on emotional induction.

https://www.mdpi.com/1424-8220/20/17/4788/pdf

Arousal Detection in Elderly People from Electrodermal Activity Using Musical Stimuli.

Photoplethysmogram (PPG) is increasingly used to provide monitoring of the cardiovascular system under ambulatory conditions. Wearable devices like smartwatches use PPG to allow long term unobtrusive monitoring of heart rate in free living conditions. PPG based heart rate measurement is unfortunately highly susceptible to motion artifacts, particularly when measured from the wrist. Traditional machine learning and deep learning approaches rely on tri-axial accelerometer data along with PPG to perform heart rate estimation. The conventional learning based approaches have not addressed the need for device-specific modeling due to differences in hardware design among PPG devices. In this paper, we propose a novel end to end deep learning model to perform heart rate estimation using 8 second length input PPG signal. We evaluate the proposed model on the IEEE SPC 2015 dataset, achieving a mean absolute error of 3.36+-4.1BPM for HR estimation on 12 subjects without requiring patient specific training. We also studied the feasibility of applying transfer learning along with sparse retraining from a comprehensive in house PPG dataset for heart rate estimation across PPG devices with different hardware design.

PPGnet: Deep Network for Device Independent Heart Rate Estimation from Photoplethysmogram

https://journals.viamedica.pl/rpor/article/download/73933/54023

Registration methods in radiotherapy.

It has become common for people to experience stress, mainly because of its eclectic nature – physical, psychological, emotional, social, etc. Unmonitored stress may prove harmful to one’s health resulting in even chronic diseases. Since stress is very subjective, stress management is not straightforward. Many attempts have been made to detect and quantify stress. However, an accurate assessment can be made from physiological measurements only. In this study, we have demonstrated how electrodermal activity (EDA), which represents the sympathetic response to stress, could be used for accurate classification of stress by developing a machine learning based classification model. 30 participants were subjected to Trier Social Stress Test (TSST), and EDA and accelerometer data were recorded using a wrist-worn device. Datasets containing stress and non-stress periods were segmented and manually tagged for model training, based on recorded stress protocol timeline. A kNN-classifier model was trained on datasets from 15 participants and tested on datasets from the remaining 15 participants, and the results were verified with salivary cortisol levels recorded before and after TSST. The proposed kNN classifier has sensitivity and specificity of 94% and 93% respectively. Motion corruptions due to hand movements were detected using the accelerometer data and were classified as ‘motion affected’. The classifier was able to classify – the baseline regions of all participants as non-stress, 93% of the TSST regions as stress and 63% of the post-stress regions as non-stress.

Electrodermal Activity based Classification of Induced Stress in a Controlled Setting

Purpose To quantify normal corneal transparency by anterior segment optical coherence tomography (AS-OCT) by measuring the average pixel intensity. To analyze the variation in the average pixel intensity in mild and severe grades of corneal opacities. Methods This is an observational, cross-sectional study of 38 eyes from 19 patients with mild or severe grades of corneal opacities greater than 3 mm and a normal contralateral cornea. AS-OCT was performed centered on the opacity with a 3 mm cruciate protocol. A similar image is taken of the contralateral clear cornea in the same quadrant. The average pixel intensity was calculated in a standardized manner using MATLAB software. Result The average pixel intensity of the normal cornea was 99.6 ± 10.9 [standard deviation (SD)]. The average pixel intensity of the mild and severe corneal opacities was 115.5 ± 9.1 and 141.1 ± 10.3, respectively. The differences were statistically significant. Conclusions AS-OCT images can be used to quantify corneal transparency. Average pixel intensity is a measure that varies significantly with varying corneal opacification.

Objective quantification of corneal haziness using anterior segment optical coherence tomography

Workplace Stress can impact the employees especially when their perception of job demands are more than what they can meet. Excessive and long term stress can have detrimental effects on both physiological and mental health. Building resilience is necessary for an individual, which helps combat the mental strain of work stress and exercise control over the work demands. At their core, stress responses are often linked to resolving the threats by increasing an individual's ability to cope. Unobtrusive and continuous monitoring of stress during work can help in understanding how stress levels change throughout a work day. In this study, stress has been evaluated from Electrocardiogram (ECG) derived Heart Rate Variability (HRV) obtained using an unobtrusive chest wearable. A total of 85 employees participated in the study and their measured stress levels were classified into four different levels as no, low, medium and high stress. The stress levels were evaluated every 5 minutes as the employees engaged in tasks like review meeting and accomplishing deadlines. Analysis revealed stress levels of employees reduced when they took breaks during work time. Females generally experienced high stress levels for much longer duration than males, whereas males experienced no, low and medium stress only a little longer than females. Also, variations in stress levels of the employees before, during and after lunch were studied to understand how food affects stress and the decrease in stress levels observed shows the impact of food intake in coping with stress.

HRV based Stress Assessment of Individuals in a Work Environment

https://journals.viamedica.pl/rpor/article/download/73851/53940

Extended localization and adaptive dose calculation using HU corrected cone beam CT: Phantom study

Assessment of image quality parameters in medical applications is crucial to produce high quality images that would significantly improve diagnoses and therapies. Solutions available in the market to assess the image quality provide experimental setups, standard test charts, and illumination setups. Parameters like sharpness, geometric distortion, and dynamic range require separate test charts and therefore can only be measured one at a time. In this paper, a single test chart to measure most of the image quality parameters has been described. A single image of this test chart could provide assessment of all the parameters considered. The size of the test chart could be customized according to the endoscopy application. An experimental setup was also designed in-house. This approach helped in developing a comprehensive and inexpensive assessment technique complying with the International Organization of Standardization (ISO) standards. Currently, the algorithms work with still images and could be extended to assess how the measured parameters would vary on a live video stream.

Amalan S

Papers

Electrodermal Activity based Classification of Induced Stress in a Controlled Setting

Objective quantification of corneal haziness using anterior segment optical coherence tomography

HRV based Stress Assessment of Individuals in a Work Environment

Extended localization and adaptive dose calculation using HU corrected cone beam CT: Phantom study

Image Quality Assessment for Endoscopy Applications