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91.
92.
S. Loerakker D. L. Bader F. P.T. Baaijens C. W.J. Oomens 《Computer methods in biomechanics and biomedical engineering》2013,16(3):338-345
Deep tissue injury (DTI) is a severe form of pressure ulcer where tissue damage starts in deep tissues underneath intact skin. Tissue deformation may play an important role in the aetiology, which can be investigated using an experimental–numerical approach. Recently, an animal-specific finite element model has been developed to simulate experiments in which muscle tissue was compressed with an indenter. In this study, the material behaviour and boundary conditions were adapted to improve the agreement between model and experiment and to investigate the influence of these adaptations on the predicted strain distribution. The use of a highly nonlinear material law and including friction between the indenter and the muscle both improved the quality of the model and considerably influenced the estimated strain distribution. With the improved model, the required sample size to detect significant differences between loading conditions can be diminished, which is clearly relevant in experiments involving animals. 相似文献
93.
S. Loerakker L.R. Solis D.L. Bader F.P.T. Baaijens V.K. Mushahwar C.W.J. Oomens 《Computer methods in biomechanics and biomedical engineering》2013,16(5):520-529
Mechanical loading of soft tissues covering bony prominences can cause skeletal muscle damage, ultimately resulting in a severe pressure ulcer termed deep tissue injury (DTI). Deformation plays an important role in the aetiology of DTI. Therefore, it is essential to minimise internal muscle deformations in subjects at risk of DTI. As an example, spinal cord-injured (SCI) individuals exhibit structural changes leading to a decrease in muscle thickness and stiffness, which subsequently increase the tissue deformations. In the present study, an animal-specific finite element model, where the geometry and boundary conditions were derived from magnetic resonance images, was developed. It was used to investigate the internal deformations in the muscle, fat and skin layers of the porcine buttocks during loading. The model indicated the presence of large deformations in both the muscle and the fat layers, with maximum shear strains up to 0.65 in muscle tissue and 0.63 in fat. Furthermore, a sensitivity analysis showed that the tissue deformations depend considerably on the relative stiffness values of the different tissues. For example, a change in muscle stiffness had a large effect on the muscle deformations. A 50% decrease in stiffness caused an increase in maximum shear strain from 0.65 to 0.99, whereas a 50% increase in stiffness resulted in a decrease in maximum shear strain from 0.65 to 0.49. These results indicate the importance of restoring tissue properties after SCI, with the use of, for example, electrical stimulation, to prevent the development of DTI. 相似文献
94.
Joshua E. Johnson 《Computer methods in biomechanics and biomedical engineering》2013,16(16):1856-1861
Measurement of static alignment of articulating joints is of clinical benefit and can be determined using image-based registration. We propose a method that could potentially improve the outcome of image-based registration by using initial manual registration. Magnetic resonance images of two wrist specimens were acquired in the relaxed position and during simulated grasp. Transformations were determined from voxel-based image registration between the two volumes. The volumes were manually aligned to match as closely as possible before auto-registration, from which standard transformations were obtained. Then, translation/rotation perturbations were applied to the manual registration to obtain altered initial positions, from which altered auto-registration transformations were obtained. Models of the radiolunate joint were also constructed from the images to simulate joint contact mechanics. We compared the sensitivity of transformations (translations and rotations) and contact mechanics to altering the initial registration condition from the defined standard. We observed that with increasing perturbation, transformation errors appeared to increase and values for contact force and contact area appeared to decrease. Based on these preliminary findings, it appears that the final registration outcome is sensitive to the initial registration. 相似文献
95.
96.
《Free radical research》2013,47(4):374-382
AbstractMitochondrial reactive oxygen species (ROS) is a key element in the regulation of several physiological functions and in the development or progression of multiple pathological events. A key task in the study of mitochondrial ROS is to establish reliable methods for measuring the ROS level in mitochondria with high selectivity, sensitivity, and spatiotemporal resolution. Over the last decade, imaging tools with fluorescent indicators from either small-molecule dyes or genetically encoded probes that can be targeted to mitochondria have been developed, which provide a powerful method to visualize and even quantify mitochondrial ROS level not only in live cells, but also in live animals. These innovative tools that have bestowed exciting new insights in mitochondrial ROS biology have been further promoted with the invention of new techniques in indicator design and fluorescent detection. However, these probes present some limitations in terms of specificity, sensitivity, and kinetics; failure to recognize these limitations often results in inappropriate interpretations of data. This review evaluates the recent advances in mitochondrial ROS imaging approaches with emphasis on their proper application and limitations, and highlights the future perspectives in the development of novel fluorescent probes for visualizing all species of ROS. 相似文献
97.
Luis A. Pérez Romasanta María José García Velloso Antonio López Medina 《Reports of Practical Oncology and Radiotherapy》2013,18(6):376-382
Functional imaging and its application to radiotherapy (RT) is a rapidly expanding field with new modalities and techniques constantly developing and evolving. As technologies improve, it will be important to pay attention to their implementation. This review describes the main achievements in the field of head and neck cancer (HNC) with particular remarks on the unsolved problems. 相似文献
98.
《Expert review of proteomics》2013,10(2):165-178
Proteomics is the study of the protein complement of a genome and employs a number of newly emerging tools. One such tool is chemical proteomics, which is a branch of proteomics devoted to the exploration of protein function using both in vitro and in vivo chemical probes. Chemical proteomics aims to define protein function and mechanism at the level of directly observed protein–ligand interactions, whereas chemical genomics aims to define the biological role of a protein using chemical knockouts and observing phenotypic changes. Chemical proteomics is therefore traditional mechanistic biochemistry performed in a systems-based manner, using either activity- or affinity-based probes that target proteins related by chemical reactivities or by binding site shape/properties, respectively. Systems are groups of proteins related by metabolic pathway, regulatory pathway or binding to the same ligand. Studies can be based on two main types of proteome samples: pooled proteins (1 mixture of N proteins) or isolated proteins in a given system and studied in parallel (N single protein samples). Although the field of chemical proteomics originated with the use of covalent labeling strategies such as isotope-coded affinity tagging, it is expanding to include chemical probes that bind proteins noncovalently, and to include more methods for observing protein–ligand interactions. This review presents an emerging role for nuclear magnetic resonance spectroscopy in chemical proteomics, both in vitro and in vivo. Applications include: functional proteomics using cofactor fingerprinting to assign proteins to gene families; gene family-based structural characterizations of protein–ligand complexes; gene family-focused design of drug leads; and chemical proteomic probes using nuclear magnetic resonance SOLVE and studies of protein–ligand interactions in vivo. 相似文献
99.
Fengzhao Yang Zhancheng Xu Jinjie Wang Feng Zan Chaoqing Dong Jicun Ren 《Luminescence》2013,28(3):392-400
In this study, we report for the first time a one‐pot approach for the synthesis of new CdSeTeS quaternary‐alloyed quantum dots (QDs) in aqueous phase by microwave irradiation. CdCl2 was used as a Cd precursor during synthesis, NaHTe and NaHSe were used as Te and Se precursors and mercaptopropionic acid (MPA) was used as a stabilizer and source of sulfur. A series of quaternary‐alloyed QDs of different sizes were prepared. CdSeTeS QDs exhibited a wide emission range from 549 to 709 nm and high quantum yield (QY) up to 57.7 %. Most importantly, the quaternary‐alloyed QDs possessed significantly long fluorescence lifetimes > 100 ns as well as excellent photostability. Results of high‐resolution transmission electron microscopy (HRTEM), energy dispersive X‐ray spectroscopy (EDX) and powder X‐ray diffraction (XRD) spectroscopy showed that the nanocrystals possessed a quaternary alloy structure with good crystallinity. Fluorescence correlation spectroscopy (FCS) showed that QDs possessed good water solubility and monodispersity in aqueous solution. Furthermore, CdSeTeS QDs were modified with alpha‐thio‐omega‐carboxy poly(ethylene glycol) (HS‐PEG‐COOH) and the modified QDs were linked to anti‐epidermal growth factor receptor (EGFR) antibodies. QDs with the EGFR antibodies as labeling probes were successfully applied to targeted imaging for EGFR on the surface of SiHa cervical cancer cells. We believe that CdSeTeS QDs can become useful probes for in vivo targeted imaging and clinical diagnosis. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
100.
Melissa A. Geller David A. Knorr David A. Hermanson Lee Pribyl Laura Bendzick Valarie Mccullar Jeffrey S. Miller Dan S. Kaufman 《Cytotherapy》2013,15(10):1297-1306
Background aimsThere is an urgent need for novel therapeutic strategies for relapsed ovarian cancer. Dramatic clinical anti-tumor effects have been observed with interleukin (IL)-2 activated natural killer (NK) cells; however, intravenous delivery of NK cells in patients with ovarian cancer has not been successful in ameliorating disease. We investigated in vivo engraftment of intraperitoneally (IP) delivered NK cells in an ovarian cancer xenograft model to determine if delivery mode can affect tumor cell killing and circumvent lack of NK cell expansion.MethodsAn ovarian cancer xenograft mouse model was established to evaluate efficacy of IP-delivered NK cells. Tumor burden was monitored by bioluminescent imaging of luciferase-expressing ovarian cancer cells. NK cell persistence, tumor burden and NK cell trafficking were evaluated. Transplanted NK cells were evaluated by flow cytometry and cytotoxicity assays.ResultsIP delivery of human NK cells plus cytokines led to high levels of circulating NK and was effective in clearing intraperitoneal ovarian cancer burden in xenografted mice. NK cells remained within the peritoneal cavity 54 days after injection and had markers of maturation. Additionally, surviving NK cells were able to kill ovarian cancer cells at a rate similar to pre-infusion levels, supporting that in vivo functionality of human NK cells can be maintained after IP infusion.ConclusionsIP delivery of NK cells leads to stable engraftment and antitumor response in an ovarian cancer xenograft model. These data support further pre-clinical and clinical evaluation of IP delivery of allogeneic NK cells in ovarian cancer. 相似文献