Raman Spectroscopy Provides a Powerful Diagnostic Tool for Accurate Determination of Albumin Glycation

We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.National Center for Research Resources (U.S.) (Grant No. P41-RR02594)Massachusetts Institute of Technology. Laser Biomedical Research Cente

More than magnetic isolation: Dynabeads as strong Raman reporters towards simultaneous capture and identification of targets

Dynabeads are superparamagnetic particles used for immunomagnetic purification of cells and biomolecules. Post-capture, however, target identification relies on tedious culturing, fluorescence staining and/or target amplification. Raman spectroscopy presents a rapid detection alternative, but current implementations target cells themselves with weak Raman signals. We present antibody-coated Dynabeads as strong Raman reporter labels whose effect can be considered a Raman parallel of immunofluorescent probes. Recent developments in techniques for separating target-bound Dynabeads from unbound Dynabeads makes such an implementation feasible. We deploy Dynabeads anti-Salmonella to bind and identify Salmonella enterica, a major foodborne pathogen. Dynabeads present signature peaks at 1000 and 1600 1/cm from aliphatic and aromatic C-C stretching of polystyrene, and 1350 1/cm and 1600 1/cm from amide, alpha-helix and beta-sheet of antibody coatings of the Fe2O3 core, confirmed with electron dispersive X-ray (EDX) imaging. Their Raman signature can be measured in dry and liquid samples even at single shot ~30 x 30-micrometer area imaging using 0.5 s, 7 mW laser acquisition with single and clustered beads providing a 44- and 68-fold larger Raman intensity compared to signature from cells. Higher polystyrene and antibody content in clusters yields to the larger signal intensity and conjugation to bacteria strengthens clustering as a bacterium can bind to more than one bead as observed via transmission electron microscopy (TEM). Our findings shed light on the intrinsic Raman reporter nature of Dynabeads, demonstrating their dual function for target isolation and detection without additional sample preparation, staining, or unique plasmonic substrate engineering, advancing their applications in heterogeneous samples like food, water, and blood.Comment: 35 pages, 19 figures, submitted to the Journal of Raman Spectroscop

Label-free characterization of ultra violet-radiation-induced changes in skin fibroblasts with Raman spectroscopy and quantitative phase microscopy

Minimizing morbidities and mortalities associated with skin cancers requires sustained research with the goal of obtaining fresh insights into disease onset and progression under specific stimuli, particularly the influence of ultraviolet rays. In the present study, label-free profiling of skin fibroblasts exposed to time-bound ultra-violet radiation has been performed using quantitative phase imaging and Raman spectroscopy. Statistically significant differences in quantifiable biophysical parameters, such as matter density and cell dry mass, were observed with phase imaging. Accurate estimation of changes in the biochemical constituents, notably nucleic acids and proteins, was demonstrated through a combination of Raman spectroscopy and multivariate analysis of spectral patterns. Overall, the findings of this study demonstrate the promise of these non-perturbative optical modalities in accurately identifying cellular phenotypes and responses to external stimuli by combining molecular and biophysical information.National Institutes of Health (U.S.) (Grant P41-EB015871-30)National Institutes of Health (U.S.) (Grant U01-NS090438-03)National Institutes of Health (U.S.) (Grant R21-NS091982-01)National Institutes of Health (U.S.) (Grant R01-HL121386-03

A Compact Wideband Crossover Coupler with Lumped Elements

A compact wideband crossover coupler with fully lumped elements is presented. To achieve a wideband operation, a three-section branch-line structure is employed for the crossover coupler. The size is significantly minimized by replacing transmission lines with lumped elements. The measurement shows that the insertion loss, isolation, and return loss are 1.7 dB, 24 dB, and 14.5 dB, respectively, at 2 GHz. The fractional bandwidth of 20-dB isolation and 3-dB insertion loss is 27%. The size of the crossover coupler is 11 mm × 9 mm, which corresponds to 0.07λ × 0.06λ at 2 GHz. This is significantly smaller than a conventional three-section branch-line crossover coupler by 95%

Reflection phase microscopy using spatio-temporal coherence of light

Many disease states are associated with cellular biomechanical changes as markers. Label-free phase microscopes are used to quantify thermally driven interface fluctuations, which allow the deduction of important cellular rheological properties. Here, the spatio-temporal coherence of light was used to implement a high-speed reflection phase microscope with superior depth selectivity and higher phase sensitivity. Nanometric scale motion of cytoplasmic structures can be visualized with fine details and three-dimensional resolution. Specifically, the spontaneous fluctuation occurring on the nuclear membrane of a living cell was observed at video rate. By converting the reflection phase into displacement, the sensitivity in quantifying nuclear membrane fluctuation was found to be about one nanometer. A reflection phase microscope can potentially elucidate biomechanical mechanisms of pathological and physiological processes.Korea Health Industry Development Institute. Korea Health Technology R&D Project (H114C3477)National Research Foundation of Korea (1R01HL121386-01A1)National Research Foundation of Korea (4R44EB012415)National Research Foundation of Korea (5R01NS051320)National Research Foundation of Korea (9P41EB015871-26A1)National Science Foundation (U.S.) (CBET-0939511)Hamamatsu CorporationSingapore-MIT Alliance. BioSystems and Micromechanics (BioSyM) Inter-Disciplinary Research GroupKorea University (Future Research Grant

Investigating Effects of Proteasome Inhibitor on Multiple Myeloma Cells Using Confocal Raman Microscopy

Due to its label-free and non-destructive nature, applications of Raman spectroscopic imaging in monitoring therapeutic responses at the cellular level are growing. We have recently developed a high-speed confocal Raman microscopy system to image living biological specimens with high spatial resolution and sensitivity. In the present study, we have applied this system to monitor the effects of Bortezomib, a proteasome inhibitor drug, on multiple myeloma cells. Cluster imaging followed by spectral profiling suggest major differences in the nuclear and cytoplasmic contents of cells due to drug treatment that can be monitored with Raman spectroscopy. Spectra were also acquired from group of cells and feasibility of discrimination among treated and untreated cells using principal component analysis (PCA) was accessed. Findings support the feasibility of Raman technologies as an alternate, novel method for monitoring live cell dynamics with minimal external perturbation

Newly developed post-operative atrial fibrillation is associated with an increased risk of late recurrence of atrial fibrillation in patients who underwent open heart surgery: Long-term follow up

Background: Herein is sought to determine whether the occurrence of post-operative atrial fibrillation (POAF) increases the risk of late recurrence of atrial fibrillation (AF) in patients undergoing open heart surgery (OHS). Methods: This study included 938 patients (56.7 ± 13.1 years old, 550 males) with no history of AF who underwent OHS. All patients were monitored continuously for development of POAF after surgery until the time of hospital discharge and received clinical follow up with serial evaluation of rhythm status. Results: Among the total population, POAF occurred in 207 (22.1%) patients and late AF in 88 (9.4%) patients during the mean follow up period of 78.1 ± 39.1 months. Development of late AF oc¬curred more frequently in patients with POAF than in those without [29.0% (60/207) vs. 3.8% (28/731), p < 0.01]. Higher septal E/e’ ratio (HR 1.04, 95% CI 1.00–1.08, p = 0.04) was an independent predic¬tor of late occurrence of AF and an episode of POAF (HR 27.12, 95% CI 8.46–86.96, p < 0.01) was the most powerful predictor. Conclusions: POAF is significantly associated with an increased risk of late AF recurrence during long-term follow up. Careful concern regarding late recurrence of AF with serial evaluation of rhythm status is required in patients with POAF

Correlation of the Korean Version of Falls Efficacy Scale-International With Quantitative Balance and Gait Parameters Through Exercise Program in Elderly Men

Objective To determine correlation of the Korean version of Falls Efficacy Scale-International (KFES-I) with other gait and balance parameters through exercise program in older men. Methods Between July 2015 and April 2018, 50 men of 103 participants in an exercise program for preventing falls who aged over 60 years, completed the evaluation before and after the program, had fear of falling (FOF), and could walk independently as an outpatient were enrolled retrospectively. The program comprised lower extremities and core muscle strengthening exercises following stretching exercises twice a week for 8 weeks. FOF using the KFES-I, Berg Balance Scale (BBS), Modified Barthel Index (MBI), stair up and gait categories in MBI (MBI-gait), and Timed Up and Go test (TUG) were evaluated. Quantitative gait and balance parameters were measured by gait analysis, posturography, and isokinetic dynamometer. They were compared before and after the program. Moreover, correlations of KFES-I with other parameters were examined. Results Fifty participants were enrolled. After the program, significant improvements were noted in right stride length (p=0.013) in gait analysis, MBI (p=0.012), BBS (p<0.000), TUG test (p<0.000), and KFES-I (p<0.000) scores. KFES-I was significantly correlated with MBI (r=-0.35, p=0.013), and MBI-gait (r=-0.341, p=0.015). Conclusion Risk of falls could be significantly improved through exercise. KFES-I had significant correlations with MBI-gait parameters. Participants showed increases in gait and balancing ability on quantitative measurements through exercises. Therefore, regular stretching, strengthening, and balancing exercises may help prevent falls in older people

Serial Assessment of Myocardial Properties Using Cyclic Variation of Integrated Backscatter in an Adriamycin-Induced Cardiomyopathy Rat Model

Although adriamycin (Doxorubicin) is one of the most effective and useful antineoplastic agents for the treatment of a variety of malignancies, its repeated administration can induce irreversible myocardial damage and resultant heart failure. Currently, no marker to detect early cardiac damage is available. The purpose of this study was to investigate whether an assessment of the acoustic properties of the myocardium could enable the earlier detection of myocardial damage after adriamycin chemotherapy. Forty Wistar rats were treated with adriamycin (2 mg/kg, i.v.) once a week for 2, 4, 6 or 8 weeks consecutively. Left ventricular ejection fraction (LVEF) was calculated using M-mode echocardiography data. The magnitude of cardiac cycle dependent variation of integrated backscatter (CVIB) of the myocardium was measured in the mid segment of the septum and in the posterior wall of the left ventricle, using a real time two dimensional integrated backscatter imaging system. LVEF was significantly lower in the adriamycin-treated 8-week group than in the controls (75 ± 9 vs 57 ± 8%, p < 0.05). Myocyte damage was only seen in the 8-week adriamycin-treated group. However, no significant changes of CVIB were observed between baseline or during follow-up in the ADR or control group. In conclusion, serial assessment of the acoustic properties of the myocardium may not be an optimal tool for the early detection of myocardial damage after doxorubicin chemotherapy in a rat model