Current Issue : January - March Volume : 2014 Issue Number : 1 Articles : 5 Articles
Background: Knowing the orientation of the head is important in many fields,\r\nincluding medicine. Many methods and measuring systems exist, but usually they\r\nuse different markers or sensors attached to the subjectâ��s head for head orientation\r\ndetermination. In certain applications these attachments may represent a burden or\r\na distraction to the subject under study which may have an unfavourable impact on\r\nthe measurement. We propose a non-contact optical method for head-to-trunk\r\norientation measurement that does not require any attachments to the subject\r\nunder study.\r\nMethods: An innovative handheld 3D apparatus has been developed for non-invasive\r\nand fast 3D shape measurements. It is based on the triangulation principle in\r\ncombination with fringe projection. The shape of the subjectâ��s upper trunk and head is\r\nreconstructed from a single image using the Fourier transform profilometry method.\r\nTwo shape measurements are required to determine the head-to-trunk orientation\r\nangles: one in the reference (neutral) position and the other one in the position of\r\ninterest. The algorithm for the head-to-trunk orientation angle extraction is based on\r\nthe separate alignment of the shape of the subjectâ��s upper trunk and head against the\r\ncorresponding shape in the reference pose. Single factor analysis of variance (ANOVA)\r\nwas used for statistical characterisation of the method precision.\r\nResults: The method and the 3D apparatus were verified in-vitro using a mannequin\r\nand a reference orientation tracker. The uncertainty of the calculated orientation was\r\n2�°. During the in-vivo test with a human subject diagnosed with cervical dystonia\r\n(aged 60), the repeatability of the measurements was 3�°. In-vitro and in-vivo comparison\r\nwas done on the basis of an experiment with the mannequin and a healthy male\r\n(aged 29). These results show that only the difference between flexion/extension\r\nmeasured angles was statistically significant. The differences between means were less\r\nthan 1�° for all ranges.\r\nConclusions: The new non-contact method enables the compensation of the\r\nmovement of the measuring instrument or the subjectâ��s body as a whole, is non-invasive,\r\nrequires little additional equipment and causes little stress for the subject and operator.\r\nWe find that it is appropriate for measurements of the head orientation with respect to\r\nthe trunk for the characterization of the cervical dystonia....
Background: Pneumatic tourniquets are medical devices that occlude blood flow to\r\ndistal part of extremities and are commonly used in upper limb surgeries to provide\r\na dry, clean and bloodless field. To decrease pressure-related injuries and potential\r\nrisk of complications subjected to the high inflation pressure of pneumatic\r\ntourniquet, minimal inflation pressures are recommended.\r\nMethods: A new occlusion pressure mathematical model for the upper limb was\r\nestablished based on the correlation analysis between several possible influencing\r\nparameters and the minimal pneumatic tourniquet pressure at which the peripheral\r\npulse disappeared was recorded using a digital plethysmograph. A prototype of an\r\nadaptive pneumatic tourniquet which automatically varies the pressure in the\r\ntourniquet cuff according to the above prediction model was developed for the\r\nupper limb which used the lowest possible inflation pressure to achieve occlusion.\r\nThe prototype comprises a blood pressure monitoring module, an inflatable\r\ntourniquet cuff, and a pressure relief mechanism to maintain an optimal cuff inflation\r\npressure. Simulation experiments were conducted to verify the function and stability\r\nof the designed adaptive pneumatic tourniquet and clinical experiments using\r\nvolunteers were undertaken to evaluate the performance of the prototype design in\r\nachieving adequate haemostasis in the upper limb.\r\nResults: Results demonstrated that the mean arterial occlusion pressure was\r\n152.3 Ã?± 16.7 mmHg, obviously below the 250 to 300 mmHg previously recommended\r\n(J Bone Joint Surg Br 68:625-628, 1986 and Arthroscopy 11:307ââ?¬â??311, 1995).\r\nConclusions: In conclusion, this adaptive method and apparatus which can provide\r\nminimal inflation pressure may be a clinically practical alternative for upper limb surgery\r\nperformed with pneumatic tourniquets....
Background: The replacement of hard tissues demands biocompatible and sometimes\r\nbioactive materials with properties similar to those of bone. Nano-composites made of\r\nbiocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have\r\nattracted attention as permanent bone substitutes due to their excellent mechanical\r\nproperties and biocompatibility.\r\nMethod: The HDPE/HA nano-composite is prepared using melt blending at different HA\r\nloading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy,\r\nand 70 kGy were used to irradiate the samples at room temperature in vacuum. The\r\neffects of accelerated ageing after gamma irradiation on morphological, mechanical and\r\nthermal properties of HDPE/HA nano-composites were measured.\r\nResults: In Vitro test results showed that the HDPE and all HDPE/HA nano-composites\r\ndo not exhibit any cytotoxicity to WISH cell line. The results also indicated that the\r\ntensile properties of HDPE/HA nano-composite increased with increasing the HA\r\ncontent except fracture strain decreased. The dynamic mechanical analysis (DMA)\r\nresults showed that the storage and loss moduli increased with increasing the HA ratio\r\nand the testing frequency. Finally, it is remarked that all properties of HDPE/HA is\r\ndependent on the irradiation dose and accelerated aging.\r\nConclusion: Based on the experimental results, it is found that the addition of 10%,\r\n20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At\r\nthe same time, the G� increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when\r\n30% HA was added to the polymer matrix. Also, significant improvements in these\r\nproperties have been observed due to irradiation. Finally, the overall properties of HDPE\r\nand its nano-composite properties significantly decreased due to aging and should be\r\ntaken into consideration in the design of bone substitutes. It is attributed that the\r\ndeveloped HDPE/HA nano-composites could be a good alternative material for bone\r\ntissue regeneration due to their acceptable properties....
Background: Cervical auscultation (CA) is an affordable, non-invasive technique used\r\nto observe sounds occurring during swallowing. CA involves swallowing\r\ncharacterization via stethoscopes or microphones, while accelerometers can detect\r\nother vibratory signals. While the effects of fluid viscosity on swallowing accelerometry\r\nsignals is well understood, there are still open questions about these effects on\r\nswallowing sounds. Therefore, this study investigated the influence of fluids with\r\nincreasing thickness on swallowing sound characteristics.\r\nMethod: We collected swallowing sounds and swallowing accelerometry signals from\r\n56 healthy participants. Each participant completed five water swallows, five swallows\r\nof nectar-thick apple juice, and five swallows of honey-thick apple juice. These\r\nswallows were completed in neutral head and chin-tuck head positions. After\r\npre-processing of collected signals, a number of features in time, frequency and\r\ntime-frequency domains were extracted.\r\nResults: Our numerical analysis demonstrated that significant influence of viscosity\r\nwas found in most of the features. In general, features extracted from swallows in the\r\nneutral head position were affected more than swallows from the chin-tuck position.\r\nFurthermore, most of the differences were found between water and fluids with higher\r\nviscosity. Almost no significant differences were found between swallows involving\r\nnectar-thick and honey-thick apple juices. Our results also showed that thicker fluids\r\nhad higher acoustic regularity and predictability as demonstrated by the\r\ninformation-theoretic features, and a lower frequency content as demonstrated by\r\nfeatures in the frequency domain.\r\nConclusions: According to these results, we can conclude that viscosity of fluids\r\nshould be considered in future investigations involving swallowing sounds....
Background: Poly (ethylene glycol) (PEG) has attracted broad interest for tissue\r\nengineering applications. The aim of this study was to synthesize 4-arm -PEG-20kDa\r\nwith the terminal group of diacrylate (4-arm-PEG-DA) and evaluate its dual\r\nfunctionality for decellularized porcine aortic valve (DAV) based on its mechanical\r\nand biological properties.\r\nMethods: 4-arm-PEG-DA was synthesized by graft copolymerization of linear PEG\r\n20,000 monomers, and characterized by IR1H NMR and 13C NMR; PEGylation of DAV\r\nwas achieved by the Michael addition reaction between propylene acyl and thiol, its\r\neffect was tested by uniaxial planar tensile testing, hematoxylin and eosin (HE) and\r\nscanning electron microscopy (SEM). Gly-Arg-Gly-Asp-Ser-Pro-Cys (GRGDSPC)\r\npeptides and vascular endothelial growth factor-165 (VEGF165) were conjugated onto\r\nDAV by branched PEG-DA (GRGDSPC-PEG-DAV-PEG-VEGF165).\r\nResults: Mechanical testing confirmed that PEG-cross-linking significantly enhanced\r\nthe tensile strength of DAV. Immunofluoresce confirmed the GRGDSPC peptides\r\nand VEGF165 were conjugated effectively onto DAV; the quantification of\r\nconjunction was completed roughly using spectrophotometry and ELISA. The\r\nhuman umbilical vein endothelial cells (HUVECs) grew and spread well on the\r\nGRGDSPC-PEG-DAV-PEG-VEGF165.\r\nConclusions: Therefore, PEGylation of DAV not only can improve the tensile strength\r\nof DAV, and can also mediate the conjugation of bioactive molecule (VEGF165 and\r\nGRGDSPC peptides) on DAV, which might be suitable for further development of\r\ntissue engineered heart valve....
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