Jung Chan Lee

A rapid antimicrobial susceptibility test based on single-cell morphological analysis

An antimicrobial susceptibility test rapidly identifies bacterial response to drugs based on imaged morphology of single cells. Microbes Get in Shape for Antibiotic Testing Conventional tests that measure bacteria susceptibility to antibiotics rely on a change in occupied area. Thus, a positive change in area indicates that the bacteria is growing and is resistant to the drug, right? Not always: Bacteria can also take on different shapes, such as filaments, or swell; these changes increase the area, but the bug is still susceptible to the antibiotic. Choi et al. therefore devised an imaging-based antibiotic susceptibility test (AST) that factors in changes in morphology, to rapidly determine whether single bacteria, confined to microwells, respond to various drugs. The authors looked at four standard strains, including antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), as well as clinical samples, in response to dozens of different antibiotics used in the clinic. The single-cell morphology AST performed as well as the gold standard, culture-based broth microdilution test, with read-out in only 4 hours. Such a rapid and accurate screen could improve time-to-answer in the clinic by avoiding conventional culture methods, thus allowing for faster decision making in administering proper antibiotics to patients. A rapid antibiotic susceptibility test (AST) is desperately needed in clinical settings for fast and appropriate antibiotic administration. Traditional ASTs, which rely on cell culture, are not suitable for urgent cases of bacterial infection and antibiotic resistance owing to their relatively long test times. We describe a novel AST called single-cell morphological analysis (SCMA) that can determine antimicrobial susceptibility by automatically analyzing and categorizing morphological changes in single bacterial cells under various antimicrobial conditions. The SCMA was tested with four Clinical and Laboratory Standards Institute standard bacterial strains and 189 clinical samples, including extended-spectrum β-lactamase–positive Escherichia coli and Klebsiella pneumoniae, imipenem-resistant Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococci from hospitals. The results were compared with the gold standard broth microdilution test. The SCMA results were obtained in less than 4 hours, with 91.5% categorical agreement and 6.51% minor, 2.56% major, and 1.49% very major discrepancies. Thus, SCMA provides rapid and accurate antimicrobial susceptibility data that satisfy the recommended performance of the U.S. Food and Drug Administration.

Development of a force-reflecting robotic platform for cardiac catheter navigation.

Electrophysiological catheters are used for both diagnostics and clinical intervention. To facilitate more accurate and precise catheter navigation, robotic cardiac catheter navigation systems have been developed and commercialized. The authors have developed a novel force-reflecting robotic catheter navigation system. The system is a network-based master-slave configuration having a 3-degree of freedom robotic manipulator for operation with a conventional cardiac ablation catheter. The master manipulator implements a haptic user interface device with force feedback using a force or torque signal either measured with a sensor or estimated from the motor current signal in the slave manipulator. The slave manipulator is a robotic motion control platform on which the cardiac ablation catheter is mounted. The catheter motions-forward and backward movements, rolling, and catheter tip bending-are controlled by electromechanical actuators located in the slave manipulator. The control software runs on a real-time operating system-based workstation and implements the master/slave motion synchronization control of the robot system. The master/slave motion synchronization response was assessed with step, sinusoidal, and arbitrarily varying motion commands, and showed satisfactory performance with insignificant steady-state motion error. The current system successfully implemented the motion control function and will undergo safety and performance evaluation by means of animal experiments. Further studies on the force feedback control algorithm and on an active motion catheter with an embedded actuation mechanism are underway.

The incretin effect in Korean subjects with normal glucose tolerance or type 2 diabetes

The incretin effect is known to be decreased in type 2 diabetes. However, there are limited data on the incretin effect in non‐Caucasian subjects. Because Asian patients with type 2 diabetes are characterized by decreased insulin secretion, this study set out to examine the incretin effect in Korean subjects with normal glucose tolerance (NGT) or type 2 diabetes.

In vivo evaluation of the pulsatile ECLS sysem

Abstract Extracorporeal life support (ECLS) systems have been increasingly applied to groups of patients with cardiorespiratory failure, including pediatric and adult patients with respiratory failure. Current pulsatile ECLS systems use a single pulsatile blood pump that generates a high inlet pressure in the membrane oxygenator. To minimize this high inlet pressure, we have developed a new and improved ECLS system, twin pulse life support (T-PLS). To analyze the advantages of T-PLS, we have compared T-PLS with a single pulsatile ECLS system. An acute heart failure model was constructed by using a pulmonary artery banding technique. Fourteen pigs (22–31 kg) were used, with cardiac outputs of 2.0 l/min and a V/Q ratio set at 1. Cannulae of 28 Fr and 18 Fr were used in the right atrium and aorta, respectively. A polypropylene hollow-fiber membrane oxygenator and four polymer valves 30 mm in diameter were used in the T-PLS system. In the single pulsatile ECLS system, Medtronic Hall monostrut valves were used. To evaluate blood cell trauma in both pulsatile ECLS systems, plasma free hemoglobin (fHb) was measured while the systems were in use. The results show that fHb levels in T-PLS are lower than fHb levels in the single pulsatile ECLS system. There is a possibility that T-PLS could be used as an ECLS system for emergency situations.

Manikin-Integrated Digital Measuring System for Assessment of Infant Cardiopulmonary Resuscitation Techniques

The process of cardiopulmonary resuscitation (CPR) involves various components that must be followed to deliver high quality of CPR. While the components commonly apply to CPR for all ages from infant to adult, there are several different suggestions for infant CPR such as two-thumb CPR and two-finger CPR. However, the comprehensive evaluation based on all these components has been difficult in the absence of proper evaluation tool. Here, we developed a new manikin-integrated, digital measuring system that objectively estimates overall performance of infant CPR by evaluating individual CPR components one by one including different hand placements. The system collects and analyzes data to present estimations in digital scores according to a new evaluation index constructed based on the previously verified one. The feasibility of the system was validated through simulations with beginners and experts in first aid, resulting in statistically significant differences between the two groups with the indication of specific weaknesses for each group which may provide a basis for creating customized CPR training strategy in compliance with the personal level. We believe that the system would become a valuable assessment tool not only for infant CPR but also for the CPR technique, in general, by reflecting every component in the evaluation.

Clinical Features of Polyarteritis Nodosa in Korea

Polyarteritis nodosa (PAN) is a systemic vasculitis characterized by multi-organ involvement with protean manifestations. We evaluated the clinical features of PAN in Korea. Twenty-seven patients were diagnosed as PAN at Seoul National University Hospital between January 1990 and July 2003. The male-to-female ratio was 1.7:1 and mean age at onset (±SD) was 47.4±20 yr. Their presenting features at diagnosis were similar to those reported previously, i.e., myalgia, muscle weakness or leg tenderness (70%), fever (52%), weight loss >4 kg (44%), skin rash (44%), peripheral edema (33%), abdominal pain (33%), and arthralgia/arthritis (30%). However, the prevalence of testicular pain or tenderness was higher (24%) than reported previously and only three (11.5%) had HBsAg positivity without liver enzyme elevation. Nine patients (33%) had a five-factor score (FFS) of 2. Fourteen patients (52%) responded to treatment, 2 patients relapsed and 4 died within 1 yr of diagnosis. During a median follow-up of 55.5 months, three of the four PAN-related deaths had an initial FFS of 2. The clinical features of PAN were not significantly different from those reported previously. However, testicular pain or tenderness was more frequent and patients with a high FFS tended to have a poorer prognosis.

Spatiotemporal characteristics of swallowing in Parkinson's disease.

The aim of this study was to quantitatively investigate spatiotemporal movement abnormalities during the pharyngeal phase of swallowing in individuals with Parkinsons disease (PD) and to investigate relationships between disease and dysphagia severities.

Shear-wave elastographic features of breast cancers: comparison with mechanical elasticity and histopathologic characteristics.

ObjectiveThe objective of this study was to compare the quantitative and qualitative shear-wave elastographic (SWE) features of breast cancers with mechanical elasticity and histopathologic characteristics. Materials and MethodsThis prospective study was conducted with institutional review board approval, and written informed consent was obtained. Shear-wave elastography was performed for 30 invasive breast cancers in 30 women before surgery. The mechanical elasticity of a fresh breast tissue section, correlated with the ultrasound image, was measured using an indentation system. Quantitative (maximum, mean, minimum, and standard deviation of elasticity in kilopascals) and qualitative (color heterogeneity and presence of signal void areas in the mass) SWE features were compared with mechanical elasticity and histopathologic characteristics using the Pearson correlation coefficient and the Wilcoxon signed rank test. ResultsMaximum SWE values showed a moderate correlation with maximum mechanical elasticity (r = 0.530, P = 0.003). There were no significant differences between SWE values and mechanical elasticity in histologic grade I or II cancers (P = 0.268). However, SWE values were significantly higher than mechanical elasticity in histologic grade III cancers (P < 0.001), which have low amounts of fibrosis, high tumor cellularity, and intratumoral necrosis. In addition, color heterogeneity was correlated with intratumoral heterogeneity of mechanical elasticity (r = 0.469, P = 0.009). Signal void areas in the masses were present in 43% of breast cancers (13 of 30) and were correlated with dense collagen depositions (n = 11) or intratumoral necrosis (n = 2). ConclusionsQuantitative and qualitative SWE features reflect both the mechanical elasticity and histopathologic characteristics of breast cancers.

The Accuracy of the Swallowing Kinematic Analysis at Various Movement Velocities of the Hyoid and Epiglottis

Objective To evaluate the accuracy of the swallowing kinematic analysis. Methods To evaluate the accuracy at various velocities of movement, we developed an instrumental model of linear and rotational movement, representing the physiologic movement of the hyoid and epiglottis, respectively. A still image of 8 objects was also used for measuring the length of the objects as a basic screening, and 18 movie files of the instrumental model, taken from videofluoroscopy with different velocities. The images and movie files were digitized and analyzed by an experienced examiner, who was blinded to the study. Results The Pearson correlation coefficients between the measured and instrumental reference values were over 0.99 (p<0.001) for all of the analyses. Bland-Altman plots showed narrow ranges of the 95% confidence interval of agreement between the measured and reference values as follows: 0.14 to 0.94 mm for distances in a still image, -0.14 to 1.09 mm/s for linear velocities, and -1.02 to 3.81 degree/s for angular velocities. Conclusion Our findings demonstrate that the distance and velocity measurements obtained by swallowing kinematic analysis are highly valid in a wide range of movement velocity.

Lapabot: a compact telesurgical robot system for minimally invasive surgery: part I. System description.

Abstract The applications of robotic minimally invasive surgery (MIS) have widened, providing new advantages such as augmented dexterity and telesurgery. However, current commercial robotic laparoscopic surgical systems still have aspects to be improved such as heavy and bulky systems not suitable for agile operations, large rotational radii of robot manipulator arms, limited remote control capacity, and absence of force feedback. We have developed a robotic laparoscopic surgical system that features compact slave manipulators. The system can simultaneously operate one laparoscope arm and up to four instrument arms. The slave robot is controlled remotely through an Ethernet network and is ready for telesurgery. The developed surgical robot has sufficient workspace to perform general MIS and has been shown to provide acceptable motion tracking control performance.