EFFECTS OF SEAT POSITION ON THE JOINT MOMENTS OF THE LOWER EXTREMITIES DURING CYCLING IN THE ELDERLY

The purpose of this study was to quantify the joint moments of the lower extremities with different seat positions during cycling in elderly. Fifteen older adults performed cycling on a self-developed bicycle ergometer at three horizontal and three vertical seat positions. The pedals were instrumented with six-component load cells to measure pedal reaction forces; and a motion capture system was used to measure body segment kinematic data. Both data sets were used to calculate joint moments during a crank cycle. The results showed that seat positions affected joint moments significantly, especially the horizontal positions. A more posterior seat position led to a more balanced loading at the hip and knee, with less peak muscle loadings. The results will be helpful for cycle design and fitting for the elderly

Biomechanical Strategies for Obstacle Crossing in Patients with Anterior Cruciate Ligament Deficiency

The current study aimed to investigate the biomechanical control strategies in patients with anterior cruciate ligament deficiency (ACLD) when crossing obstacles of different heights. Eighteen patients with unilateral ACLD and sixteen age-matched healthy controls were recruited. They crossed obstacles of heights of 10%, 20% and 30% of their leg lengths at a self-selected pace while the kinematic and kinetic data were measured and analyzed using inverse dynamics analysis. Patients with ACLD were found to avoid using the quadriceps on both affected and unaffected sides during stance phase. Training programs on both quadriceps are needed for more efficient rehabilitation of the patients with unilateral ACLD

Influence of Step Length and Cadence on the Sharing of the Total Support Moments Between the Lower Limbs During Level Walking

The current study aimed to investigate the effects of walking speed on the inter-limb sharing of whole body support in terms of total support moments (Ms) during walking. A multiple linear regression model was conducted to explore the relationship between gait speed in terms of step length and cadence, and the difference of the first and second peaks of the Ms (DMs) during walking. The DMs were found to increase with either increased step length or cadence. Walking with greater speed relied more on the leading limb to provide support for the forward progression of the body. In addition, variations of gait speed parameters affected the load-sharing pattern between the lower limbs during weight transfer of walking. Gait speed parameters have to be taken as covariates when analysing the coordination of the kinetics between lower limbs

Comparison and prediction of pullout strength of conical and cylindrical pedicle screws within synthetic bone

<p>Abstract</p> <p>Background</p> <p>This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength using synthetic and cadaveric bone as specimens. In the literature, the Chapman's formula has been widely proposed to predict the pullout strength of screws with constant outer and inner diameters (cylindrical screws).</p> <p>Methods</p> <p>This study formulated the pullout strength of the conical and cylindrical screws as the functions of material, screw, and surgery factors. The predicted pullout strength of each screw was compared to the experimentally measured data. Synthetic bones were used to standardize the material properties of the specimen and provide observation of the loosening mechanism of the bone/screw construct.</p> <p>Results</p> <p>The predicted data from the new formulae were better correlated with the mean pullout strength of both the cylindrical and conical screws within an average error of 5.0% and <it>R</it>²= 0.93. On the other hand, the average error and <it>R</it>²value of the literature formula were as high as -32.3% and -0.26, respectively.</p> <p>Conclusion</p> <p>The pullout strength of the pedicle screws was the functions of bone strength, screw design, and pilot hole. The close correlation between the measured and predicted pullout strength validated the value of the new formulae, so as avoid repeating experimental tests.</p

Conserved charged amino acid residues in the extracellular region of sodium/iodide symporter are critical for iodide transport activity

<p>Abstract</p> <p>Background</p> <p>Sodium/iodide symporter (NIS) mediates the active transport and accumulation of iodide from the blood into the thyroid gland. His-226 located in the extracellular region of NIS has been demonstrated to be critical for iodide transport in our previous study. The conserved charged amino acid residues in the extracellular region of NIS were therefore characterized in this study.</p> <p>Methods</p> <p>Fourteen charged residues (Arg-9, Glu-79, Arg-82, Lys-86, Asp-163, His-226, Arg-228, Asp-233, Asp-237, Arg-239, Arg-241, Asp-311, Asp-322, and Asp-331) were replaced by alanine. Iodide uptake abilities of mutants were evaluated by steady-state and kinetic analysis. The three-dimensional comparative protein structure of NIS was further modeled using sodium/glucose transporter as the reference protein.</p> <p>Results</p> <p>All the NIS mutants were expressed normally in the cells and targeted correctly to the plasma membrane. However, these mutants, except R9A, displayed severe defects on the iodide uptake. Further kinetic analysis revealed that mutations at conserved positively charged amino acid residues in the extracellular region of NIS led to decrease NIS-mediated iodide uptake activity by reducing the maximal rate of iodide transport, while mutations at conserved negatively charged residues led to decrease iodide transport by increasing dissociation between NIS mutants and iodide.</p> <p>Conclusions</p> <p>This is the first report characterizing thoroughly the functional significance of conserved charged amino acid residues in the extracellular region of NIS. Our data suggested that conserved charged amino acid residues, except Arg-9, in the extracellular region of NIS were critical for iodide transport.</p

Production of Active Nonglycosylated Recombinant B-Chain of Type-2 Ribosome-Inactivating Protein from Viscum articulatum and Its Biological Effects on Peripheral Blood Mononuclear Cells

Type-2 ribosome-inactivating proteins, composed of a toxic A-chain and lectin-like B-chain, display various biological functions, including cytotoxicity and immunomodulation. We here cloned the lectin-like B-chain encoding fragment of a newly identified type-2 RIP gene, articulatin gene, from Viscum articulatum, into a bacterial expression vector to obtain nonglycosylated recombinant protein expressed in inclusion bodies. After purification and protein refolding, soluble refolded recombinant articulatin B-chain (rATB) showed lectin activity specific toward galactoside moiety and was stably maintained while stored in low ionic strength solution. Despite lacking glycosylation, rATB actively bound leukocytes with preferential binding to monocytes and in vitro stimulated PBMCs to release cytokines without obvious cytotoxicity. These results implicated such a B-chain fragment as a potential immunomodulator

Efficient Prodrug Activator Gene Therapy by Retroviral Replicating Vectors Prolongs Survival in an Immune-Competent Intracerebral Glioma Model.

Prodrug activator gene therapy mediated by murine leukemia virus (MLV)-based retroviral replicating vectors (RRV) was previously shown to be highly effective in killing glioma cells both in culture and in vivo. To avoid receptor interference and enable dual vector co-infection with MLV-RRV, we have developed another RRV based on gibbon ape leukemia virus (GALV) that also shows robust replicative spread in a wide variety of tumor cells. We evaluated the potential of GALV-based RRV as a cancer therapeutic agent by incorporating yeast cytosine deaminase (CD) and E. coli nitroreductase (NTR) prodrug activator genes into the vector. The expression of CD and NTR genes from GALV-RRV achieved highly efficient delivery of these prodrug activator genes to RG-2 glioma cells, resulting in enhanced cytotoxicity after administering their respective prodrugs 5-fluorocytosine and CB1954 in vitro. In an immune-competent intracerebral RG-2 glioma model, GALV-mediated CD and NTR gene therapy both significantly suppressed tumor growth with CB1954 administration after a single injection of vector supernatant. However, NTR showed greater potency than CD, with control animals receiving GALV-NTR vector alone (i.e., without CB1954 prodrug) showing extensive tumor growth with a median survival time of 17.5 days, while animals receiving GALV-NTR and CB1954 showed significantly prolonged survival with a median survival time of 30 days. In conclusion, GALV-RRV enabled high-efficiency gene transfer and persistent expression of NTR, resulting in efficient cell killing, suppression of tumor growth, and prolonged survival upon CB1954 administration. This validates the use of therapeutic strategies employing this prodrug activator gene to arm GALV-RRV, and opens the door to the possibility of future combination gene therapy with CD-armed MLV-RRV, as the latter vector is currently being evaluated in clinical trials