We analyze the erythrocyte aggregation by the biospeckle laser phenomenon and calculate characteristic parameters to develop non-invasive hemorheological techniques. Biospeckle is more complex than other light-based techniques, such as light transmission, providing information about the dynamics of the scatterers, their size, and morphology. Dextran 500 kDa combined with plasma and phosphate-buffered saline was used to induce controlled in vitro erythrocyte aggregation. Red blood cell aggregation was studied using an objective speckle setup in a microchip sample chamber. The speckle grain sizes were determined, and parameters to characterize the morphology of the erythrocyte aggregates were proposed. The inertia moment and the correlation coefficient were determined to assess the cells aggregation dynamics.
Hair cells of the auditory and vestibular systems are capable of detecting sounds that induce sub-nanometer vibrations. These specialized cells convert mechanical deflections due to sound waves into electrical signals that are relayed to the brain through afferent neurons. This transduction involves mechanically gated ion channels that open following the deflection of mechanoreceptive hair bundles that reside on top of these cells. Moreover, internal energy-consuming processes in the hair bundle can amplify deflections and even generate innate oscillations in the absence of input. The transduction process ultimately leads to emission of the neurotransmitter glutamate, which in turn evokes spike trains in the innervating afferents. We performed measurements on in vitro preparations of the sacculus from the American bullfrog (Rana catesbeiana). Mechanical force was imposed on the hair bundle with a stimulus probe controlled with a piezo actuator and electrical signals were sent through the nerve with a bipolar suction electrode. Under these conditions, we observed variations in the intensity of light emitted by the Ca2+ indicator Fluo-8. Spatial and temporal recordings of Ca2+ hotspots were performed on the area near the hair cell synapse, in order to elucidate the temporal dynamics of neuronal activity. Further development of this optical technique would enable the study of voltage spikes in the afferent nerve fibers, so as to correlate them to the hair bundle mechanical movement.
In this work, we studied the nature of the molecular bonds involved in the red blood cell aggregation process by the coherent anti-Stokes Raman spectroscopy technique. Images were acquired with a commercial Leica TCS SP8 CARS confocal microscope (Leica Microsystems GmbH, Wetzlar, Germany) temporally and spatially overlapping the pulses of two sources in the focal plane of the microscope. A pump wavelength of 810 nm to 817 nm was used for the CARS mode simultaneously with the Stokes beam at 1064 nm to excite the vibratory resonance of the symmetric hydrocarbon bonds in the lipids and that of the bonds in amino acids of the proteins. The Raman shift was also observed at the 1200 cm−1 range to study possible variations in the sialic acid on the cell membrane produced by concentrations of dextran 500 in the suspension medium. Curves of lifetime emission distribution were obtained for untreated erythrocytes and treated erythrocytes with dextran 500, particularly at a pump wavelength of 904 nm.
The study of erythrocyte (RBC) aggregation is of great interest because of its implications on human health, alterations in erythrocyte aggregation can lead to microcirculatory problems. An optical-chip based system was developed using laser transmission techniques in order to evaluate and characterize RBC aggregation. Studies are carried out with in vitro altered RBC by non-enzymatic glycosylation. Several samples were analyzed, and by computational data processing, characteristic parameters were found, describing RBC aggregation kinetics in order to improve the early detection in clinical environments of these anomalies, generally present in vascular diseases such as hypertension and diabetes.
The study of red blood cell (RBC) aggregation is of great interest because of its implications for human health. Altered RBC aggregation can lead to microcirculatory problems as in vascular pathologies, such as hypertension and diabetes, due to a decrease in the erythrocyte surface electric charge and an increase in the ligands present in plasma. The process of erythrocyte aggregation was studied in stasis situation (free shear stresses), using an optical chip based on the laser transmission technique. Kinetic curves of erythrocyte aggregation under different conditions were obtained, allowing evaluation and characterization of this process. Two main characteristics of blood that influence erythrocyte aggregation were analyzed: the erythrocyte surface anionic charge (EAC) after digestion with the enzyme trypsin and plasmatic protein concentration in suspension medium using plasma dissolutions in physiological saline with human albumin. A theoretical approach was evaluated to obtain aggregation and disaggregation ratios by syllectograms data fitting. Sensible parameters (Amp100, t1\2) regarding a reduced erythrocyte EAC were determined, and other parameters (AI, M-Index) resulted that are representative of a variation in the plasmatic protein content of the suspension medium. These results are very useful for further applications in biomedicine.
Traditional techniques to evaluate the aggregation of red blood cells by optical methods require large sample volume and provide parameters that vary significantly from one method to another. A simplified variant of a chip system previously developed by Shin et al. (2009)1 based on light transmission for measuring erythrocyte aggregation is presented. Through a detailed analysis of intensity versus time curves, relevant information about erythrocyte aggregation and its variables is obtained. Parameters that provide more accuracy for the diagnosis of patients in order to have an immediate application in Clinical Medicine are proposed.
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