Ming-Yih Lee

The sit-to-stand movement in stroke patients and its correlation with falling

OBJECTIVE To use kinetic assessment of the sit-to-stand movement as a means of sorting out those stroke patients at risk for falling. DESIGN A retrospective study, using a force platform to assess sit-to-stand performance and to determine its correlation with falls in stroke patients. SETTING Hospital-based rehabilitation units. METHODS Thirty-three stroke patients (18 fallers, 15 nonfallers) and 25 age-matched healthy subjects were included in this study. Subjects sat in an adjustable chair with their feet on two force plates and performed the standing up/sitting down movement at a self-paced, comfortable speed. RESULTS The rate of rise in force (dF/dT) was significantly lower in stroke fallers than in stroke nonfallers and healthy subjects (23.78+/-17.38, 55.23+/-31.24, and 85.96+/-42.4 percent body weight per second, respectively [p < .005]). The center of pressure sway in mediolateral direction during rising/ sitting down was much greater in stroke fallers than in stroke nonfallers or healthy subjects (p < .05). Body weight distribution was asymmetric on the feet of stroke patients, with much more body weight on their sound side. CONCLUSIONS The significantly lower rate of rise in force and greater postural sway while rising/sitting down may be useful in identifying stroke patients who are at risk for falling.

Using extracorporeal life support to resuscitate adult postcardiotomy cardiogenic shock: Treatment strategies and predictors of short-term and midterm survival

BACKGROUND Postcardiotomy extracorporeal life support (ECLS) is a resource-demanding therapy with varied results among institutions. An organized protocol was necessary to improve the effectiveness of this therapy. METHODS AND RESULTS A total of 110 patients received ECLS due to refractory postcardiotomy cardiogenic shock between January 2003 and June 2009, and were eligible for inclusion in this retrospective study. Preoperative, perioperative, and postoperative variables were collected, including the European system for cardiac operative risk evaluation (EuroSCORE) and markers of ECLS-related organ injuries. All variables were analyzed for possible associations with mortality in hospital, and after hospital discharge. The mean age, additive EuroSCORE, and left ventricular ejection fraction (LVEF) for all patients was 60 (+/-14) years, 9 (+/-6), and 43% (+/-20%) respectively. Sixty-seven patients were weaned from ECLS and 46 survived to hospital discharge. The mean duration of ECLS support was 143 h (+/-112 h). Multivariate analysis revealed that an age of >60 years, a necessity for postoperative continuous arteriovenous hemofiltration, a maximal serum total bilirubin >6 mg/dL, and a need for ECLS support for >110 h were independent predictors of in-hospital mortality. In addition, persistent heart failure with LVEF <30% was an independent predictor of mortality after hospital discharge. A risk-predicting score for in-hospital mortality associated with postcardiotomy ECLS was developed for clinical application. CONCLUSION Based on the abovementioned findings, a comprehensive protocol for postcardiotomy ECLS was designed. The primary objective was to achieve adequate hemodynamics within the first 24h of initiating ECLS. Other objectives of the protocol included a consistent approach to safe anticoagulation while on ECLS, a process to make decisions within 7 days of initiating ECLS, and patient follow-up after hospital discharge.

Effect of intermittent cigarette smoke inhalation on tibial lengthening : Experimental study on rabbits

We investigated the effect of intermittent cigarette smoke inhalation on the bone healing of tibial lengthening in rabbits. Thirty-eight male rabbits were divided into two groups of 19 animals each. The first group went through intermittent cigarette smoke inhalation, and the second group did not go through intermittent cigarette smoke inhalation. Each animals right tibia was lengthened 5 mm using an uniplanar lengthening device. Five animals of each group were killed at 4, 6, and 8 weeks postoperatively for biomechanical testing, and one animal of each group was killed at 2, 4, 6, and 8 weeks postoperatively for histologic study. Using the contralateral nonoperated tibia as an internal control, we found that torsional strength of the lengthened tibia of the smoke inhalation group was decreased significantly compared with the non-smoke inhalation group. The mean percent of maximal torque at 4, 6, and 8 weeks were 22.0, 66.3, and 78.6%, respectively, in the smoke inhalation group, whereas the mean percent of maximal torque were 48.0, 84.1, and 90.8% %, respectively, in non-smoke inhalation group (one-tailed t test, p < 0.01, p < 0.01, and p < 0.05 at 4, 6, and 8 weeks, respectively). Our histologic observations revealed that the granulation tissue resorption, bone formation, and remodeling were delayed in smoke inhalation group. The results of this study suggest that intermittent inhalation of cigarette smoke delays, but does not prevent, the bone healing in tibial lengthening.

Resuscitation of non-postcardiotomy cardiogenic shock or cardiac arrest with extracorporeal life support: The role of bridging to intervention

BACKGROUND To investigate the predictors of adverse outcomes of extracorporeal life support (ECLS) in rescuing adult non-postcardiotomy cardiogenic shock or cardiac arrest (non-PC CS/CA). MATERIALS AND METHODS This retrospective study included 60 adult patients receiving ECLS for non-PC CS/CA in a single institution between June 2003 and June 2010. The exclusion criteria were (1) pre-ECLS cardiac surgeries in the same admission and (2) age<18 years. Pre-ECLS and ECLS characteristics were compared in patients surviving to hospital discharge and those who did not. Mortalities after hospital discharge were also investigated. RESULTS Of the 38 patients weaned from ECLS, 32 survived to discharge. Acute myocardial infarction (AMI) and myocarditis were the most common aetiologies in this study. Forty patients experienced pre-ECLS conventional cardiopulmonary resuscitation (C-CPR) and 29 required an ECLS-assisted CPR (E-CPR). Thirteen patients who received E-CPR had profound anoxic encephalopathy later. In-hospital mortality was similar in AMI patients who underwent emergent coronary artery bypass grafting (CABG) after a failed percutaneous coronary intervention (PCI, 43%, 5/11) and those who underwent PCI only (58%, 7/12). Aetiologies other than myocarditis (odds ratio (OR) 11.0, 95% confidence interval (CI) 1.5-78.5), requirement for E-CPR (OR 5.6, 95% CI 1.5-22.0) and profound anoxic encephalopathy (OR 8.9, 95% CI 2.0-40.5) were predictors of in-hospital mortality. No risk factors of mortality after hospital discharge were identified. CONCLUSION ECLS was effective in bridging adults with non-PC CS/CA to definite treatments. Their prognosis depended on the cause of collapse and the severity of the post-cardiac arrest syndrome.

Biomechanical analysis of location of lag screw of a dynamic hip screw in treatment of unstable intertrochanteric fracture.

OBJECTIVE The aim of this study was to assess the most adequate location of a lag screw of a dynamic hip screw in the treatment of an unstable intertrochanteric fracture. METHODS Six pairs of proximal femora obtained from fresh adult cadavers were inflicted with iatrogenic unstable intertrochanteric fractures. Fractures of both sides were stabilized with two different favored locations of a lag screw and tested by a Material Testing System machine with increased loads to evaluate the relative migration of the femoral head. RESULTS There was significant difference (p < 0.05) with less migration of the femoral head by inferior insertion of a lag screw in the frontal plane and central insertion in the coronal plane. CONCLUSIONS Based on theoretical and experimental considerations, the most adequate location of a lag screw of a dynamic hip screw should be inferior in the frontal plane and central in the coronal plane.

Custom implant design for patients with cranial defects

Three-dimensional image reconstruction and rapid prototyping models improve defect evaluation, treatment planning, implant design, and surgeon accuracy. It is found that both 3-D imaging and physical models are helpful for the evaluation of cranial defects, treatment planning, and custom implant design. While 3-D imaging can be used on a routine basis, the physical skull models could be a useful additional tool, especially when the cranial defects are rare, unusual, or difficult. In this case, the introduction of a rapid prototyping stereolithographic medical model for manufacturing a large cranioplasty implant is considered to be an improvement over other traditional techniques. Because of the accuracy of the physical model, the surgeon has a good understanding of the cranial defect and precise fitting implants can be fabricated in order to re-establish skull contours for the patient. In addition, the excellent fitting and fixation techniques of cranioplasty have reduced operating time significantly.

Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction.

Osteogenesis of adipose-derived stem cells on polycaprolactone-β-tricalcium phosphate scaffold fabricated via selective laser sintering and surface coating with collagen type I.

The current study aimed to fabricate three‐dimensional (3D) polycaprolactone (PCL), polycaprolactone and β‐tricalcium phosphate (PCL–TCP) scaffolds via a selective laser‐sintering technique (SLS). Collagen type I was further coated onto PCL–TCP scaffolds to form PCL–TCP–COL scaffolds. The physical characters of these three scaffolds were analysed. The osteogenic potential of porcine adipose‐derived stem cells (pASCs) was compared among these three scaffolds in order to find an optimal scaffold for bone tissue engineering. The experimental results showed no significant differences in pore size and porosity among the three scaffolds; the porosity was ca. 75–77% and the pore size was ca. 300–500 µm in all three. The compressive modulus was increased from 6.77 ± 0.19 to 13.66 ± 0.19 MPa by adding 30% β‐TCP into a 70% PCL scaffold. No significant increase of mechanical strength was found by surface‐coating with collagen type I. Hydrophilicity and swelling ratios showed statistical elevation (p < 0.05) after collagen type I was coated onto the PCL–TCP scaffolds. The in vitro study demonstrated that pASCs had the best osteogenic differentiation on PCL–TCP–COL group scaffolds, due to the highest ALP activity, osteocalcin mRNA expression and mineralization. A nude mice experiment showed better woven bone and vascular tissue formation in the PCL–TCP–COL group than in the PCL group. In conclusion, the study demonstrated the ability to fabricate 3D, porous PCL–TCP composite scaffolds (PCL:TCP = 70:30 by weight) via an in‐house‐built SLS technique. In addition, the osteogenic ability of pASCs was found to be enhanced by coating COL onto the PCL–TCP scaffolds, both in vitro and in vivo. Copyright

Entropy-based feature extraction and decision tree induction for breast cancer diagnosis with standardized thermograph images

In this study, a computer-assisted entropy-based feature extraction and decision tree induction protocol for breast cancer diagnosis using thermograph images was proposed. First, Beier-Neely field morphing and linear affine transformation were applied in geometric standardization for whole body and partial region respectively. Gray levels of pixel population at the same anatomical position were statistically analyzed for abnormal region classification. Morphological closing and opening operations were used to identify unified abnormal regions. Three types of 25 feature parameters (i.e. 10 geometric, 7 topological and 8 thermal) were extracted for parametric factor analysis. Positive and negative abnormal regions were further reclassified by decision trees to induce the case-based diagnostic rules. Finally, anatomical organ matching was utilized to identify the corresponding organ with the positive abnormal regions. To verify the validity of the proposed case-based diagnostic protocol, 71 and 131 female patients with and without breast cancer were analyzed. Experimental results indicated that 1750 abnormal regions (703 positive and 1047 negative) were detected and 822 branches were broken down into the decision space. Fourteen branches were found to have more than 4 positive abnormal regions. These critical diagnostic paths with less than 10% of positive abnormal regions (61/703=8.6%) can effectively classify more than half of the cancer patients (42/71=59.2%) in the abovementioned 14 branches.

New layer-based imaging and rapid prototyping techniques for computer-aided design and manufacture of custom dental restoration

Fixed partial denture produced by conventional method is greatly relied on the skill and experience of dental technician. Its quality and accuracy depends mostly on the technicians subjective judgment. In addition, the manual process involves many procedures which require a long time to complete. Most important, it does not preserve any quantitative information for future retrieval. In this paper, a new device for scanning denture images and reconstructing 3D digital information of dental model by abrasive computer tomography (ACT) was designed in-house and proposed. The fixed partial denture was then produced by the rapid prototyping (RP) and computer numerical control (CNC) machining methods based on ACT scanned digital information. A force feedback sculptor (freeform system, sensible technologies Inc., USA) accompany with 3D Touch technology was applied to modify the morphology or the design of denture. It enables the dentist to perform digital manipulation of denture profile with real-time and user-friendly human interactive operation without relying on CAD/CAM technician or dental technician. In this article, the comparison of conventional manual operation and digital manufacture using both RP and CNC machining technologies for denture production was presented. In addition, a digital custom denture manufacturing protocol integrating proposed computer abrasive teeth profile scanning, computer-aided denture design, 3D touchable force feedback feature modification and advanced denture manufacturing techniques were suggested. These proposed methods provide a solid evidence that digital design and manufacturing technologies may become a new avenue for custom-made denture design, analysis, and production in 21st century.