Seung Yeol Lee

Plasmonic Nanostructures for Nano-Scale Bio-Sensing

The optical properties of various nanostructures have been widely adopted for biological detection, from DNA sequencing to nano-scale single molecule biological function measurements. In particular, by employing localized surface plasmon resonance (LSPR), we can expect distinguished sensing performance with high sensitivity and resolution. This indicates that nano-scale detections can be realized by using the shift of resonance wavelength of LSPR in response to the refractive index change. In this paper, we overview various plasmonic nanostructures as potential sensing components. The qualitative descriptions of plasmonic nanostructures are supported by the physical phenomena such as plasmonic hybridization and Fano resonance. We present guidelines for designing specific nanostructures with regard to wavelength range and target sensing materials.

Optical Sensing Method for Screening Disease in Melon Seeds by Using Optical Coherence Tomography

We report a noble optical sensing method to diagnose seed abnormalities using optical coherence tomography (OCT). Melon seeds infected with Cucumber green mottle mosaic virus (CGMMV) were scanned by OCT. The cross-sectional sensed area of the abnormal seeds showed an additional subsurface layer under the surface which is not found in normal seeds. The presence of CGMMV in the sample was examined by a blind test (n = 140) and compared by the reverse transcription-polymerase chain reaction. The abnormal layers (n = 40) were quantitatively investigated using A-scan sensing analysis and statistical method. By utilizing 3D OCT image reconstruction, we confirmed the distinctive layers on the whole seeds. These results show that OCT with the proposed data processing method can systemically pick up morphological modification induced by viral infection in seeds, and, furthermore, OCT can play an important role in automatic screening of viral infections in seeds.

The effect of age on cervical sagittal alignment: normative data on 100 asymptomatic subjects.

Study Design. Retrospective study. Objective. To determine age-related changes in cervical sagittal alignment using whole-spine standing radiographs in asymptomatic adults. Summary of Background Data. Modern surgical techniques have emphasized the importance of maintaining proper sagittal alignment. But there is a paucity of literature investigating age-related changes in cervical sagittal alignment. Methods. One hundred healthy unoperated adults who were free of spinal problems obtained whole-spine standing radiographs. They consisted of 2 groups divided by age: those in their 20s and those older than 60 years. Each group had an equal ratio of males and females. Distances from C2 as well as C7 plumb lines to the following points were measured: thoracic and lumbar apex as well as the posterior superior corner of the S1 vertebral body. In addition, Cobb angles for C0–C2, C2–C7, thoracic kyphotic angle, lumbar lordotic angle, and T1 sagittal slope angles were measured. Results. The distance between the C2 and C7 plumb lines did not vary with age. The thoracic apex shifted caudally from T6 in the younger group to T7 in the older group. The most common lumbar apex was L4 for both groups. The distance from C2, as well as C7 plumb lines to the posterior superior corner of the S1 vertebral body, as well as the thoracic apex increased significantly in the older group. On the contrary, the distance from the 2 plumb lines to the lumbar apex decreased in the older group. Also, C2–C7 angle increased and T1 sagittal slope angle decreased in the older group compared with the younger group. However, no difference was found for the other Cobb angles between the 2 groups. Conclusion. The distances between the plumb lines from C2 and C7 were maintained but C2–C7 sagittal angle increased with aging. Level of Evidence: 4

A Statistical Model-Based Residual Echo Suppression

In this letter, we propose a novel residual echo suppression (RES) algorithm based on a statistical model constructed in the acoustic echo cancellation framework. In the proposed approach, all the possible near-end and far-end signal conditions are classified into four distinct hypotheses, and the power spectral density estimation is carried out according to the result of hypothesis testing. The distribution of each signal component is characterized by a parametric model, and the conventional likelihood ratio test is performed to make an optimal decision. The experimental results show that the proposed algorithm yields improved performance compared to that of the previous RES technique.

Incidence of Deep Vein Thrombosis after Major Lower Limb Orthopedic Surgery: Analysis of a Nationwide Claim Registry

Purpose We aimed to evaluate the nationwide incidence and risk factors for symptomatic deep vein thrombosis (DVT) after major lower limb orthopedic surgeries. Materials and Methods The Korean Health Insurance Review and Assessment Service database was used to retrospectively identify International Classification of Disease-10 codes for DVT and operation codes representing hip arthroplasty, knee arthroplasty, and hip fracture surgeries. The age- and gender-adjusted annual incidence of DVT, rates of major lower limb orthopedic surgeries, and the postoperative incidence of DVT according to the surgical procedure were assessed. Results The age- and gender-adjusted annual incidence of DVT was 70.67 per 100000 persons/year. Compared to patients aged <49 years, the relative risk of DVT was five times higher in patients aged 50-69 and 10 times higher in patients aged >70 years (p<0.001). Females showed a greater relative risk for DVT than males (1.08; p<0.001). The incidence of postoperative DVT, according to the type of surgery, was significantly greater for knee replacement arthroplasty than for other forms of surgery (p<0.002). The relative risk of postoperative DVT was higher in females in knee replacement arthroplasty (1.47) and hip fracture surgery (2.25) groups, although relatively lower in those who underwent hip replacement arthroplasty (0.97). Conclusion Among major lower limb surgeries, advanced age, female gender, and undergoing a knee replacement arthroplasty were found to be risk factors for developing postoperative DVT. These findings further emphasize the need for orthopedic surgeons to consider the development of DVT after surgery in high-risk patients.

Risk factors associated with amputation-free survival in patient with diabetic foot ulcers.

Purpose To determine the 1-year survival rate, 1-year amputation-free survival rate and the risk factors of amputation for patients with diabetic foot ulcers. Materials and Methods One hundred seventy-three patients with diabetic foot ulcers were included in our study. Mean patient age was 67.5 (range, 29 to 87, SD ±11.4) years. 74% of the patients were male. Time from study entry to amputation and time to death were evaluated separately as censored event times by Kaplan-Meier curves and log-rank tests. A multivariate Cox proportional hazards regression analysis was carried out for determining the risk factors of amputation. Results The survival rate and amputation-free survival rate were 96.5% (n=167), 65.9% (n=114), respectively, over one year study period. Severity of ulcer was the strongest significant risk factor of amputation [hazard ratio (HR): 7.99; confidence interval (CI): 3.12 to 20.47]. Peripheral artery disease was also independent risk factor of amputation (HR: 2.64; CI: 1.52 to 4.59). Conclusion In assessing the prognosis of diabetic foot ulcers, clinicians should consider the severity of ulcer and presence of peripheral artery disease. Our study provides important insights into clinical practice and supplementary information for both physicians and patients.

Types and arrangement of thyroid shields to reduce exposure of surgeons to ionizing radiation during intraoperative use of C-arm fluoroscopy.

Study Design. Measurement of radiation dose from C-arm fluoroscopy during a simulated intraoperative use in spine surgery. Objective. To assess how the radiation dose is affected by changes in the types of thyroid shields used and by the arrangements or ways in which they are worn during the intraoperative use of C-arm fluoroscopy. Summary of Background Data. Although the danger to the thyroid from exposure to radiation is well known, there are no guidelines for the proper use of thyroid shields. Methods. Two photoluminescence dosimeters were used to measure the dose of scattered radiation arriving at the location of the thyroid in a whole-body phantom in the position of the surgeon. On an operating table beside this setup was an anthropomorphic chest phantom representing a patient for which treatment with C-arm fluoroscopy was simulated. Radiation doses were measured using 3 different arrangements of the thyroid shield: worn tightly, worn loosely, and worn loosely with a bismuth masking reagent. The same tests were performed using 2 kinds of thyroid shield: lead and lead-equivalent. Results. For the lead-shield group, radiation doses were measured in 3 arrangements; worn tightly, worn loosely, and worn loosely with a bismuth masking reagent, for which the results were 1.91 ± 0.13, 2.35 ± 0.22, and 1.86 ± 0.13 &mgr;Sv/min, respectively. Wearing the shield tight against the throat and wearing it loose with a bismuth masking reagent led to lower radiation exposure levels than by simply wearing the shield loosely (P ⩽ 0.001). For the lead-equivalent shield group, doses were measured for the same 3 arrangements, for which the results were 1.79 ± 0.12, 1.82 ± 0.11, and 1.74 ± 0.12 &mgr;Sv/min. Lower scattered radiation doses were delivered to the thyroid in the lead-equivalent thyroid shield group compared with the lead thyroid shield group (P ⩽ 0.001). The unshielded thyroid group received a radiation dose of 16.32 ± 0.48 &mgr;Sv/min. Conclusion. The use of some form of thyroid shield is essential during the use of C-arm fluoroscopy. It was found that the best way to reduce scattered radiation exposure to the thyroid was wearing the thyroid shield tightly or wearing it loosely in combination with a bismuth masking reagent. Level of Evidence: 2

Short-term effects of proximal femoral derotation osteotomy on kinematics in ambulatory patients with spastic diplegia.

The aim of this retrospective study was to determine the short-term effects of proximal femoral derotation osteotomy (FDO) on gait in 53 ambulatory patients with spastic diplegia controlling all confounding procedures. All patients showed a jump gait pattern and had undergone bilateral rectus femoris transfer, distal hamstring lengthening, and tendo-Achilles lengthening as a single-event multilevel surgery. Of these, additional bilateral proximal FDOs were included in 25 patients, defined as the FDO group; the other 28 patients were defined as the no-FDO group. Kinematic variables, such as pelvic tilt, minimal hip flexion in stance, hip rotation, and foot progression angle, were compared between the two groups at postoperative 1 year. Hip extension, hip rotation, and hip adduction improved significantly after surgery in the FDO group (P<0.001, P=0.004, P=0.028), but not in the no-FDO group. Foot progression angle improved in both groups, but the degree of improvement was significantly greater in the FDO group (P=0.004). In conclusion, FDO improved hip rotation, hip adduction, and hip extension as well as foot progression angle in the ambulatory patients with spastic diplegia showing a jump gait.

What Are the Risk Factors Associated with Urinary Retention after Orthopaedic Surgery

This study investigates the overall rate of urinary retention in a large cohort of unselected orthopaedic patients who had either general or regional anesthesia and defines the risk factors for postoperative urinary retention in that cohort of patients. A total of 15,681 patients who underwent major orthopaedic surgery with general or spinal/epidural anesthesia were included. Postoperative urinary retention was defined as any patient who required a postoperative consultation to the urologic department regarding voiding difficulty. Age at surgery, sex, type of surgery, medical history including hypertension and diabetes mellitus, and type of anesthesia were analyzed as potential predictor variables. There were 365 postoperative patients who required urology consults for urinary retention (2.3%). Older age at surgery (OR, 1.035; P < 0.0001), male sex (OR, 1.522; P = 0.0004), type of surgery (OR, 1.506; P = 0.0009), history of hypertension (OR, 1.288; P = 0.0436), and history of diabetes mellitus (OR, 2.038; P < 0.0001) were risk factors for urinary retention after orthopaedic surgery. Advanced age, male sex, joint replacement surgery, history of hypertension, and diabetes mellitus significantly increased the risk of urinary retention. In patients with these risk factors, careful postoperative urological management should be performed.

Comparison of Manual Balance and Balance Board Tests in Healthy Adults

Objective To investigate the correlations of scores on the Timed Up and Go (TUG) test and the Single Leg Stance (SLS) test with stability scores on the Biodex Balance System (BBS) in healthy adults. Method The postural balance of 73 participants was measured on the TUG and SLS tests and with the Overall Stability Index (OSI) on the BBS. The participants were divided into groups by age and by times on the TUG and SLS. The correlations between TUG or SLS and OSI scores were analyzed by groups. Results TUG scores were significantly correlated with OSI scores in age under 65 years, TUG over 10 seconds and SLS over 30 seconds groups (level 12). TUG scores were also correlated with OSI in total (level 10) and TUG under 10 seconds groups (level 2). However, there were no significant relationships between SLS and OSI scores. Conclusion OSI scores on the BBS are significantly correlated with TUG scores, especially at the easy levels. According to the findings of present study, relatively easy BBS levels are considered to assess the postural balance in healthy adults.