Yeon Soo Lee

Excessive Humeral External Rotation Results in Increased Shoulder Laxity

Background The quantitative relationship between increased anterior shoulder laxity and increased humeral external rotation observed in throwers remains unclear. Hypothesis An elongated anterior capsule, especially the anterior band of the inferior glenohumeral ligament, produced by excessive humeral external rotation will result in increased anterior shoulder laxity and increased humeral external rotation. Study Design Controlled laboratory study. Methods Seven cadaveric shoulders were tested to measure the humeral rotational range of motion, glenohumeral translations, and length of the anterior band of the inferior glenohumeral ligament. Data were collected for the intact shoulders and after nondestructive stretching of 10%, 20%, and 30% beyond maximum humeral external rotation. Results Nondestructive excessive external rotational stretching resulted in a significant increase in superior (30%, 3.3 mm) and inferior (30%, 2.3 mm) length of the anterior band of the inferior glenohumeral ligament, external rotation (30%, 35°), and anterior (30%, 2.4 mm), inferior (30%, 2.2 mm), and anterior-posterior (30%, 5.1 mm) translations. There were significant positive linear correlations between the length of the anterior band of the inferior glenohumeral ligament, external rotation, and anterior translation. Conclusions Excessive humeral external rotation results in an elongation of the anterior band of the inferior glenohumeral ligament and an increase in anterior and inferior glenohumeral translations and humeral external rotation. Clinical Relevance Repetitive excessive humeral external rotation observed in throwers may be one of the biomechanical causes for increased shoulder laxity and increased humeral external rotation.

Path of glenohumeral articulation throughout the rotational range of motion in a thrower's shoulder model.

Background Overhead-throwing athletes have increased external and diminished internal glenohumeral rotation that may alter glenohumeral kinematics. Purpose To quantify the kinematic changes present in a cadaveric model of a throwers shoulder. Study Design Controlled laboratory study. Methods In 8 fresh-frozen cadaveric shoulders, the rotator cuff and overlying muscles were removed, and the glenohumeral capsule, coracoacromial ligament, and coracohumeral ligament were left intact. The scapula was fixed, and the humerus was placed in 90° of shoulder abduction in a 6 degrees of freedom testing device. A compressive force of 44 N was applied. A throwers shoulder model was created, and sequential conditions were examined: intact, after anterior stretching, and after the addition of posterior-inferior capsular plication. Kinematic measurements were obtained through a complete range of glenohumeral rotation. Results Glenohumeral external rotation increased 16%, from 149° to 173° (P <. 001), after stretching in external rotation and remained increased by 11% to 166° (P <. 001) after posterior-inferior capsular plication. With the addition of the posterior-inferior capsular plication, internal rotation averaged 7°, which was not significantly different from the intact state (11°, P =. 55) or the stretched state (16°, P =. 07). The total glenohumeral rotation after stretching followed by posterior-inferior capsular plication did not differ significantly from intact state (P =. 25). At maximum external rotation, the humeral head apex was shifted posteriorly in the stretched (P =. 003) and plicated (P <. 001) states compared with the intact state. The humeral head apex was posteriorly displaced at 135° and 150° of external rotation compared with the intact condition (P =. 039 and. 049, respectively). In maximum internal rotation, anterior stretching had no significant effect on the humeral head apex position. However, after posterior-inferior capsular plication, the humeral head apex was significantly shifted inferiorly (P =. 005) and anteriorly (P =. 03) in maximum internal rotation compared with the intact state. Conclusion Significant changes in glenohumeral motion occur in this model during the simulated late-cocking and follow through phases of throwing. In this model, posterior capsular tightness alters the humeral head position most profoundly during the deceleration and follow-through phases of throwing.

Mito-GSAAC: mitochondria prediction using genetic ensemble classifier and split amino acid composition

Mitochondria are all-important organelles of eukaryotic cells since they are involved in processes associated with cellular mortality and human diseases. Therefore, trustworthy techniques are highly required for the identification of new mitochondrial proteins. We propose Mito-GSAAC system for prediction of mitochondrial proteins. The aim of this work is to investigate an effective feature extraction strategy and to develop an ensemble approach that can better exploit the advantages of this feature extraction strategy for mitochondria classification. We investigate four kinds of protein representations for prediction of mitochondrial proteins: amino acid composition, dipeptide composition, pseudo amino acid composition, and split amino acid composition (SAAC). Individual classifiers such as support vector machine (SVM), k-nearest neighbor, multilayer perceptron, random forest, AdaBoost, and bagging are first trained. An ensemble classifier is then built using genetic programming (GP) for evolving a complex but effective decision space from the individual decision spaces of the trained classifiers. The highest prediction performance for Jackknife test is 92.62% using GP-based ensemble classifier on SAAC features, which is the highest accuracy, reported so far on the Mitochondria dataset being used. While on the Malaria Parasite Mitochondria dataset, the highest accuracy is obtained by SVM using SAAC and it is further enhanced to 93.21% using GP-based ensemble. It is observed that SAAC has better discrimination power for mitochondria prediction over the rest of the feature extraction strategies. Thus, the improved prediction performance is largely due to the better capability of SAAC for discriminating between mitochondria and non-mitochondria proteins at the N and C terminus and the effective combination capability of GP. Mito-GSAAC can be accessed at http://111.68.99.218/Mito-GSAAC. It is expected that the novel approach and the accompanied predictor will have a major impact to Molecular Cell Biology, Proteomics, Bioinformatics, System Biology, and Drug Development.

Error in Acetabular Socket Alignment due to the Thick Anterior Pelvic Soft Tissues

The aim of this study was to assess how much the digitizing error attributable to the thick soft tissues in the anterior pelvic area can affect the targeted acetabular socket alignment. The acetabular socket orientation angle was measured by using a synthetic pelvic model and an OrthoPilot total hip arthroplasty (Aesculap AG & Co KG, Tuttlingen, Germany) navigation system. The anterior pelvic plane was defined using 3 bony landmarks: the ipsilateral and contralateral anterior superior iliac spines (ASIS) and the center of the 2 pubic tubercles. The digitization error of 1 cm at the ipsilateral ASIS, contralateral ASIS, and the center of the two pubic tubercles resulted in 1.8 degrees , 4.4 degrees , and -6.8 degrees in anteversion, and 1.4 degrees , 0.2 degrees , and -0.2 degrees in abduction, respectively. The current navigation system based on the anterior pelvic plane may produce considerable error in guiding the acetabular socket anteversion for patients with thick soft tissue in the anterior pelvic area.

Intelligent churn prediction in telecom: employing mRMR feature selection and RotBoost based ensemble classification

Churn prediction in telecom has recently gained substantial interest of stakeholders because of associated revenue losses.Predicting telecom churners, is a challenging problem due to the enormous nature of the telecom datasets. In this regard, we propose an intelligent churn prediction system for telecom by employing efficient feature extraction technique and ensemble method. We have used Random Forest, Rotation Forest, RotBoost and DECORATE ensembles in combination with minimum redundancy and maximum relevance (mRMR), Fisher’s ratio and F-score methods to model the telecom churn prediction problem. We have observed that mRMR method returns most explanatory features compared to Fisher’s ratio and F-score, which significantly reduces the computations and help ensembles in attaining improved performance. In comparison to Random Forest, Rotation Forest and DECORATE, RotBoost in combination with mRMR features attains better prediction performance on the standard telecom datasets. The better performance of RotBoost ensemble is largely attributed to the rotation of feature space, which enables the base classifier to learn different aspects of the churners and non-churners. Moreover, the Adaboosting process in RotBoost also contributes in achieving higher prediction accuracy by handling hard instances. The performance evaluation is conducted on standard telecom datasets using AUC, sensitivity and specificity based measures. Simulation results reveal that the proposed approach based on RotBoost in combination with mRMR features (CP-MRB) is effective in handling high dimensionality of the telecom datasets. CP-MRB offers higher accuracy in predicting churners and thus is quite prospective in modeling the challenging problems of customer churn prediction in telecom.

Dynamic Mechanical Characteristics of Expanded Polypropylene Foams

Expanded polypropylene (EPP) foams have been widely used as protective materials in automotive bumpers, safety helmets, etc., but their dynamic behavior is not well defined. In the current study, quasi-static compression tests and dynamic tests using a split Hopkinson pressure bar were performed to investigate the effect of material density on the absorption of impact energy and the stress–strain curve. Three kinds of EPP specimen with densities of 20, 30, and 60 kg/m were tested. With the increase in the strain rate from 0.17 to 1857 s , the stiffness of the 20 kg/m specimen remarkably increased, whereas that of the 60 kg/m specimen did not. It is also shown that when the strain rate increased from 0.17 to 1857 s , the energy absorption became 3.7 times in 20 kg/m specimens whereas 2 times in 60 kg/m specimens. A higher density of EPP foam resulted in a greater absorption of energy. *Author to whom correspondence should be addressed. E-mail: hsyoon@chonnam.ac.kr Figures 1, 2, 6, 8 and 10 appear in color online: http://cel.sagepub.com JOURNAL OF CELLULAR PLASTICS Volume 46 — January 2010 43 0021-955X/10/01 0043–13

Antitumor effect of adriamycin-encapsulated nanoparticles of poly(DL-lactide-co-glycolide)-grafted dextran

10.00/0 DOI: 10.1177/0021955X09346363 The Author(s), 2010. Reprints and permissions: http://www.sagepub.co.uk/journalsPermissions.nav The energy that is absorbed during dynamic loading is much higher than that during static loading. These results are important in the development of a protective structure with polymer foams in views of the service energy and the level of service stress.Expanded polypropylene (EPP) foams have been widely used as protective materials in automotive bumpers, safety helmets, etc., but their dynamic behavior is not well defined. In the current study, quasi-static compression tests and dynamic tests using a split Hopkinson pressure bar were performed to investigate the effect of material density on the absorption of impact energy and the stress—strain curve. Three kinds of EPP specimen with densities of 20, 30, and 60 kg/m3 were tested. With the increase in the strain rate from 0.17 to 1857 s-1, the stiffness of the 20 kg/m3 specimen remarkably increased, whereas that of the 60 kg/m3 specimen did not. It is also shown that when the strain rate increased from 0.17 to 1857 s-1, the energy absorption became 3.7 times in 20 kg/m3 specimens whereas 2 times in 60 kg/m 3 specimens. A higher density of EPP foam resulted in a greater absorption of energy. The energy that is absorbed during dynamic loading is much higher than that during static loading. These results ar...

High revision rate of hydroxyapatite-coated ABG-I prosthesis

In this study, we prepared adriamycin (ADR)-encapsulated core-shell type nanoparticles of a poly(DL-lactide-co-glycolide) (PLGA) grafted-dextran (DexLG) copolymer and evaluated its antitumor activity in vitro and in vivo. The particle size of ADR-encapsulated DexLG nanoparticles was around 50-200 nm and the morphology was spherical shapes at transmission electron microscopy (TEM) observation. Since reconstitution of lyophilized nanoparticles is essential to practical use in vivo, ADR-encapsulated DexLG nanoparticles were lyophilized and reconstituted them into deionized water. Although reconstitution process caused increase of particle size, drug release behavior of nanoparticles was not significantly changed before and after reconstitution process. The ADR-encapsulated DexLG nanoparticles were less cytotoxic than free ADR plus empty nanoparticles at in vitro, while empty DexLG nanoparticles did not significantly affect cell viability. Even if free ADR plus empty nanoparticles are most effective to inhibit tumor growth at tumor-induced animal model using CT-26 cells, ADR-encapsulated DexLG nanoparticles showed increased survivability of mice. These results indicated that ADR-encapsulated DexLG nanoparticles are promising vehicles for antitumor drug delivery.

All-trans retinoic acid-incorporated nanoparticles of deoxycholic acid-conjugated dextran for treatment of CT26 colorectal carcinoma cells.

BackgroundThe aim of this study was to investigate the causes of the high revision rate of the hydroxyapatite-coated Anatomique Benoist Girard (ABG-I) prosthesis.MethodsWe performed 204 total hip arthroplasties (THAs) at our hospital between March 1992 and December 1996. Of the 204 THA patients, 129 were followed up; the mean duration of follow-up was 12.2 years (range 10.0–14.5 years). There were 113 male patients and 16 female patients, with an average age of 53 years (30–83 years) at the time of surgery. The reasons for THA were avascular necrosis in 119 hips, acetabular dysplasia in 8 hips, and traumatic arthritis in 2 hips.ResultsThe Harris hip score was 47.3 preoperatively and 86.4 at the last follow-up. The linear polyethylene wear was an average of 0.29 mm/year. Acetabular osteolysis was seen in 113 cases (88%). Altogether, 61 (47.2%) acetabular cups were revised for aseptic loosening in 38 hips, polyethylene wear and osteolysis in 20 hips, recurrent dislocation in 2 hips, and deep infection in 1 hip. Femoral osteolysis was observed in 100 cases (77.5%). The femoral stem was revised in 4 hips (3.1%).ConclusionWe observed that the fatal detriment to ABG-I acetabular cup survival in long-term follow-up was periacetabular osteolysis followed by aseptic loosening.

The Optimum Tension for Bridging Sutures in Transosseous-Equivalent Rotator Cuff Repair A Cadaveric Biomechanical Study

Purpose All-trans retinoic acid (RA)-incorporated nanoparticles were prepared using deoxycholic acid-conjugated dextran (DexDA). Anticancer activity of RA-incorporated DexDA nanoparticles were tested in vitro and in vivo. Methods RA-incorporated nanoparticles were prepared by dialysis. Antiproliferative and anti-invasive potential of RA-incorporated nanoparticles were studied using CT26 colorectal carcinoma cells. Results RA-incorporated nanoparticles have small particle sizes of around 70–300 nm and spherical shapes. The higher drug-feeding ratio and higher substitution degree of deoxycholic acid in the conjugates resulted in higher drug contents, lower loading efficiency, and larger particle size. RA release rate became slower at higher drug contents and higher substitution degree of deoxycholic acid in the DexDA conjugates. The antiproliferation activity, anti-invasive activity, and matrix metalloproteinase 2 expression of RA-incorporated nanoparticles against CT26 cells in vitro was similar to RA. However, RA-incorporated nanoparticles had superior antimetastatic activity in an animal pulmonary metastatic model of CT26 cells compared to RA itself. Conclusion RA-incorporated nanoparticles showed similar anticancer activity in vitro and superior antimetastatic activity in vivo in a pulmonary metastatic model of CT26 cells. We suggest that RA-incorporated nanoparticles are promising vehicles for efficient delivery of RA.