| Summary: | 碩士 === 國立陽明大學 === 生醫光電工程研究所 === 98 === A report by the United States Renal Data System in 2009 indicates that the incidence of End Stage Renal Disease in Taiwan is among the highest in the world. For patients suffering from serious renal disease, hemodialysis is the most common method of dialysis therapy worldwide. In hemodialysis, blood purification of uremic patients is achieved by urine detoxification through artificial kidney.
We applied jumping optical tweezers to trap and stretch individual human erythrocytes (or red blood cells, RBCs) to measure the RBC deformability and to study the correlation between the RBC deformability and the “seriousness” of renal disease as well as its correlation with the effect of hemodialysis treatment.
In our jumping optical tweezers system, a laser beam, diffracted by an acousto-optic modulator (AOM), was coupled into a high NA objective lens via appropriate optics to serve as the trapping beam. The focal spot was scanned discretely (or jumped) between two points by controlling the voltage of the radio-frequency (RF) driving the AOM. At a scanning frequency ~1kHz, the jumping focal spots served as a pair of parallel laser tweezers. With appropriate laser power and jumping distance, individual erythrocytes were trapped in the focal plane and stretched along the scanning direction and their deformability was measured. Besides, with a theoretical model, which allows us to calculate the stretching optical force as a function the jumping distance, in conjunction with the experimental data on the corresponding stretched length of the RBC’s major axis, the effective elastic constant of each individual RBC was determined.
By comparing the deformability and the effective elastic constant of individual RBC samples from both healthy people and also from patients with uremia, we found that compared with healthy people, the deformability of RBCs of patient with uremia is slightly lower, and the effective elastic constant is slightly higher. Comparing the RBC deformability for patients with uremia before and after hemodialysis treatment, we found that the deformability increased, and the elastic constant decreased after hemodialysis treatment. Approximately 90% of the sever uremia patients also suffer from anemia, and clinically, the severity of anemia is judged by hematocrit %. Our results also indicate that the more severe the anemia patients (based on hematocrit %) the larger the decrement in RBC effective elastic constant after hemodialysis treatment.
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