Knee Angles and Axes Crosstalk Correction In Gait, Cycling, and Elliptical Training Exercises

When conducting motion analysis using 3-dimensional motion capture technology, errors in marker placement on the knee results in a widely observed phenomenon known as “crosstalk” [1-18] in calculated knee joint angles (i.e., flexion-extension (FE), adduction-abduction (AA), internal-external rotation (IE)). Principal Component Analysis (PCA) has recently been proposed as a post hoc method to reduce crosstalk errors and operates by minimizing the correlation between the knee angles [1, 2]. However, recent studies that have used PCA have neither considered exercises, such as cycling (C) and elliptical training (E), other than gait (G) nor estimated the corrected knee axes following PCA correction. The hypothesis of this study is that PCA can correct for crosstalk in G, C, and E exercises but that subject-specific PCA corrected axes differ for these exercises. Motion analysis of the selected exercises were conducted on 8 normal weight (body mass index (BMI) = 21.70 +/- 3.20) and 7 overweight participants (BMI = 27.45 +/- 2.45). An enhanced Helen Hayes marker set with 27 markers was used to track kinematics. Knee joint FE, AA, and IE angles were obtained with Cortex (Motion Analysis, Santa Rosa, CA) software and corrected using PCA to obtain corrected angles for each exercise. Exercise-specific corrected knee joint axes were determined by finding axes that reproduced the shank and ankle body vectors taken from Cortex when used with the PCA corrected angles. Then, PCA corrected gait axes were used as a common set of axes for all exercises to find corresponding knee angles. Paired t-tests assessed if FE-AA angle correlations changed with PCA. Multivariate Paired Hotelling’s T-Square tests assessed if the PCA corrected knee joint axes were similar between exercises. ANOVA was used to assess if Cortex angles, PCA corrected angles, and knee angles using PCA corrected gait axes were different. Reduced FE-AA angle correlations existed for G (p\u3c0.001 for Cortex and p=0.85 for PCA corrected), C (p=0.01 for Cortex and p=0.77 for PCA corrected), and E (p\u3c0.001 for Cortex and p=0.77 for PCA corrected). Differences in the PCA corrected knee axes were found between G and C (p\u3c0.0014). Then, differences were found between Cortex, PCA corrected, and C and E knee angles using the PCA corrected G axes (p\u3c0.0056). The results of this study suggest that if PCA is used to reduce crosstalk errors in motions other than G then it is recommended to adopt the use of a PCA corrected axes set determined from G to produce the PCA corrected angles

Principal component analysis of gait and cycling experiments: Crosstalk error reduction and corrected knee axes

Crosstalk is a leading source of error in motion analysis [1-2]. Due to incorrect flexion axis direction that develops from marker placement error, crosstalk results in a strong, anatomically incorrect correlation between flexion-extension (FE) and adduction-abduction (AA) motions [1-2]. Thus, crosstalk limits the ability of biomechanical models to reflect the “true” motion of the knee. Principal Component Analysis (PCA) has been proposed as a post-hoc correction for crosstalk in prior gait studies [1-2]; however, previous studies have not proposed a method to determine PCA corrected knee axes. Further, it is not clear how PCA should be implemented in motion analysis studies that involve several exercises, on the same subjects, involving a relatively high range of flexion angles. The long-term goal of this study is to determine accurate knee kinematics in a variety of exercises performed by the same subjects. This study tests two hypotheses: (1) PCA corrects for crosstalk between FE and AA angles in gait and cycling and (2) PCA corrected knee axes are similar for gait and cycling. The aims are to (1) determine PCA corrected knee angles in gait and cycling for the same subjects and their corresponding FE-AA correlations, (2) develop and implement an algorithm for determining PCA corrected knee FE and AA axes, and (3) compare the PCA corrected FE and AA axes for the same subjects to determine if they are similar in gait and cycling

PolySat Helmholtz Cage

The MagCal5 Helmholtz cage project is an interdisciplinary approach to provide the PolySat/CubeSat research lab with a magnetic testing environment for the calibration of magnetic components and verification of various control laws. The Cal Poly CubeSat organization is the home of the CubeSat Specification, and acts as a testing and integration facility for CubeSats built by universities across the world. The PolySat organization is a CubeSat developer that works with numerous industry partners to design, manufacture, and operate CubeSats to further scientific advancement. The addition of a magnetic test stand to the lab will allow CubeSat to extend to the range of testing it can provide to other universities and will allow PolySat to perform more extensive attitude determination and control system testing on their CubeSats before they are put into orbit

Knee biomechanics during cycling are similar for normal weight and obese subjects

Osteoarthritis (OA) is a degenerative disease of cartilage and bone tissue, and is linked to more than 70% of total hip and knee replacements [1]. In 1994 the direct and indirect costs of OA in the United States were $155 billion [2] and in 2006 OA resulted in approximately$10.5 billion in hospital charges [3]. Obesity is a risk factor for OA [1, 3, 4], likely due to increased knee loading [5, 6] and varus malalignment [7] in gait. Seated cycling has been recommended as a weight-loss exercise with lower knee loads than walking or jogging [8]. However, lack of biomechanical studies for obese subjects in exercises, other than gait, impedes selection of exercises that may best prevent knee OA development in the obese population. This study tests the hypothesis that cycling knee kinematics and kinetics are not different for normal weight (NW) and obese (OB) subjects. The long-term goal of our research group is to calculate knee joint loading and kinematics during select exercises to aid in selection of weight-loss exercises that minimize risk of OA development. The objectives of this study are to (1) conduct cycling experiments with a motion capture system to calculate internal knee kinematics and kinetics and (2) compare knee kinematics and kinetics for normal weight and obese subjects during cycling

ANTENATAL DETECTION OF CHROMOSOMAL ABNORMALITIES COMBINING QF-PCR AND CYTOGENETIC ANALYSIS

Aim: To compare the diagnostic values and limitations of quantitative fluorescent polymerase chain reaction (QF-PCR) and conventional cytogenetic analysis in prenatal diagnosis of chromosomal abnormalities. Methods: A prospective study included simultaneous QF-PCR and cytogenetic analysis of 133 prenatal samples routinely obtained by amniocentesis or chorionic villus sampling (CVS). Additionally, QF-PCR analysis was performed on 14 tissue samples collected after termination of pregnancy (TOP) for which karyotyping could not be performed due to culture failure. Results: Among 133 analyzed prenatal samples, chromosomal abnormalities were diagnosed in 12 cases (9%), including 10 cases of numerical chromosomal aberrations and two cases with unbalanced structural rearrangements. Nine out of 12 chromosomal abnormalities were also detected with QF-PCR. However, all cases of major aneuploidies were successfully disclosed with QF-PCR, resulting in 100% detection rate for chromosomes 21, 18, 13, X and Y. Using a set of markers specific for chromosomes 21, 18 and 13, QF-PCR analysis of tissues collected after TOP revealed chromosomopathy in 21.4% of cases (two cases of trisomy 18 and one triploidy). A comparison of STR markers confirmed monozygosity in two monochorionic/diamniotic twin pregnancies. Conclusion: QF-PCR has been shown as a rapid and reliable method for prenatal diagnosis of the most common chromosomal aneuploidies, and as an adequate alternative to conventional karyotyping in cases where cytogenetic analysis is not possible due to failure of culturing process. However, conventional cytogenetics still presents a gold standard for the detection of structural aberrations and rare aneuploidies

Decision support for organ offers in liver transplantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111780/1/lt24113.pd

Silver(I) complexes containing antifungal azoles: significant improvement of the anti-Candida potential of the azole drug after its coordination to the silver(I) ion

Inspired by the emergence of resistance to currently available antifungal therapy and by the great potential of metal complexes for the treatment of various diseases, we synthesized three new silver(I) complexes containing clinically used antifungal azoles as ligands, [Ag(ecz)2]SbF6 (1, ecz is econazole), {[Ag(vcz)2]SbF6}n (2, vcz is voriconazole), and [Ag(ctz)2]SbF6 (3, ctz is clotrimazole), and investigated their antimicrobial properties. The synthesized complexes were characterized by mass spectrometry, IR, UV-vis and 1H NMR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction analysis. In the mononuclear complexes 1 and 3 with ecz and ctz, respectively, the silver(I) ion has the expected linear geometry, in which the azoles are monodentately coordinated to this metal center through the N3 imidazole nitrogen atom. In contrast, the vcz-containing complex 2 has a polymeric structure in the solid state in which the silver(I) ions are coordinated by four nitrogen atoms in a distorted tetrahedral geometry. DFT calculations were done to predict the most favorable structures of the studied complexes in DMSO solution. All the studied silver(I) complexes have shown excellent antifungal and good to moderate antibacterial activities with minimal inhibitory concentration (MIC) values in the ranges of 0.01–27.1 and 2.61–47.9 μM on the selected panel of fungi and bacteria, respectively. Importantly, the complexes 1–3 have exhibited a significantly improved antifungal activity compared to the free azoles, with the most pronounced effect observed in the case of complex 2 compared to the parent vcz against Candida glabrata with an increase of activity by five orders of magnitude. Moreover, the silver(I)-azole complexes 2 and 3 significantly inhibited the formation of C. albicans hyphae and biofilms at the subinhibitory concentration of 50% MIC. To investigate the impact of the complex 3 more thoroughly on Candida pathogenesis, its effect on the adherence of C. albicans to A549 cells (human adenocarcinoma alveolar basal epithelial cells), as an initial step of the invasion of host cells, was studied

Donation after Cardiac Death Liver Transplantation: Predictors of Outcome

We aimed to identify recipient, donor and transplant risk factors associated with graft failure and patient mortality following donation after cardiac death (DCD) liver transplantation. These estimates were derived from Scientific Registry of Transplant Recipients data from all US liver-only DCD recipients between September 1, 2001 and April 30, 2009 (n = 1567) and Cox regression techniques. Three years post-DCD liver transplant, 64.9% of recipients were alive with functioning grafts, 13.6% required retransplant and 21.6% died. Significant recipient factors predictive of graft failure included: age ≥ 55 years, male sex, African–American race, HCV positivity, metabolic liver disorder, transplant MELD ≥ 35, hospitalization at transplant and the need for life support at transplant (all, p ≤ 0.05). Donor characteristics included age ≥ 50 years and weight >100 kg (all, p ≤ 0.005). Each hour increase in cold ischemia time (CIT) was associated with 6% higher graft failure rate (HR 1.06, p 100 kg and CIT also increased patient mortality (all, p ≤ 0.035). These findings are useful for transplant surgeons creating DCD liver acceptance protocols.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79115/1/j.1600-6143.2010.03293.x.pd

Clinical Outcomes and Quality of Life in Recipients of Livers Donated after Cardiac Death

Donation after cardiac death (DCD) has expanded in the last decade in the US; however, DCD liver utilization has flattened in recent years due to poor outcomes. We examined clinical and quality of life (QOL) outcomes of DCD recipients by conducting a retrospective and cross-sectional review of patients from 2003 to 2010. We compared clinical outcomes of DCD recipients (n=60) to those of donation after brain death (DBD) liver recipients (n=669) during the same time period. DCD recipients had significantly lower rates of 5-year graft survival (P<0.001) and a trend toward lower rates of 5-year patient survival (P=0.064) when compared to the DBD cohort. In order to examine QOL outcomes in our cohorts, we administered the Short Form Liver Disease Quality of Life questionnaire to 30 DCD and 60 DBD recipients. The DCD recipients reported lower generic and liver-specific QOL. We further stratified the DCD cohort by the presence of ischemic cholangiopathy (IC). Patients with IC reported lower QOL when compared to DBD recipients and those DCD recipients without IC (P<0.05). While the results are consistent with clinical experience, this is the first report of QOL in DCD recipients using standardized measures. These data can be used to guide future comparative effectiveness studies

Set of Small Molecule Polyurethane (PU) Model Substrates: Ecotoxicity Evaluation and Identification of PU Degrading Biocatalysts

Polyurethanes (PUs) are an exceedingly heterogeneous group of plastic polymers, widely used in a variety of industries from construction to medical implants. In the past decades, we have witnessed the accumulation of PU waste and its detrimental environmental impacts. PUs have been identified as one of the most toxic polymers leaching hazardous compounds derived both from the polymer itself and the additives used in production. Further environmental impact assessment, identification and characterization of substances derived from PU materials and establishing efficient degradation strategies are crucial. Thus, a selection of eight synthetic model compounds which represent partial PU hydrolysis products were synthesized and characterized both in terms of toxicity and suitability to be used as substrates for the identification of novel biocatalysts for PU biodegradation. Overall, the compounds exhibited low in vitro cytotoxicity against a healthy human fibroblast cell line and virtually no toxic effect on the nematode Caenorhabditis elegans up to 500 µg mL−1, and two of the substrates showed moderate aquatic ecotoxicity with EC50 values 53 µg mL−1 and 45 µg mL−1, respectively, on Aliivibrio fischeri. The compounds were successfully applied to study the mechanism of ester and urethane bond cleaving preference of known plastic-degrading enzymes and were used to single out a novel PU-degrading biocatalyst, Amycolatopsis mediterranei ISP5501, among 220 microbial strains. A. mediterranei ISP5501 can also degrade commercially available polyether and polyester PU materials, reducing the average molecular number of the polymer up to 13.5%. This study uncovered a biocatalyst capable of degrading different types of PUs and identified potential enzymes responsible as a key step in developing biotechnological process for PU waste treatment options